Medical image data plays a critical role in health care today. Whatever the context of image processing , they are supposed to be treated as highly sensitive. Unfortunately, currently available image-processing tools also enable very sophisticated malicious modification of their content.This paper is focused on the assessment of the effectiveness of selected so-called zero watermarking methods (ones that do not cause any modification of an image sample), in the protection of the integrity, and proving authorship, of these medical image studies. We have studied many zero watermarking methods and selected one representative from each type of known algorithms for comparison.We have conducted a series of simulations over a huge research database of anonymized medical image studies (patient examinations). Emerging networks of health professionals, medical communities, patients, organizations, and other stakeholders are reshaping regional radiology practices these days. The technologies being employed for global medical imaging enable the integration of common radiology concepts and the reconciliation of global radiology. New opportunities also bring new risks to this field.Due to the easy distribution of multimedia data  via the Internet and the wide availability of powerful image-processing tools , it has become difficult for the authorized users (or owners) of image data to protect its originality, prove their ownership, prevent misrepresentation, unauthorized use, misappropriation, and so on.Many new techniques based on watermarking have been introduced in the past few years. Current digital watermarking methods represent a good alternative to enforce many of the aforementioned rights. A critical review of some so-called zero watermark-based techniques, highly relevant for medical imaging, has been proposed in this paper.There are two main fields of interest in digital medical image protection. The first one is the protection of originality, where the goal is to ensure or enforce originality of an image because images with unauthorized modifications cannot be used for diagnostic purposes. The second one is proof of authorship because specialists using medical images for scientific and educational purposes do not intend their work to be copied and reused without the authors’ permission.Watermarking is not meant as a competitor of another DICOM image protection mechanisms like a digital signature but as a complementary one. The digital signature can ensure bit-by-bit conformity of two DICOM images, including image metadata. Watermarking protects the image part only, but on the other hand, it can provide more information than a digital signature. The digital signature provides binary output only—images (or more precisely files) are or are not identical. Zero watermarking can provide some similarity measure as well. In the case of composite images like CT, where the DICOM entity consists of many slices = images, each slice should be protected by watermark separately. This apparent disadvantage has one meaningful benefit: in case someone has modified just a few slices, e.g., slices depicting a tumor, watermarking will identify the modified slices. The price for this ability of watermarking is the necessity of storing as many watermarks as many slices we need to protect.This paper analyzes the abilities of zero watermarking algorithms to serve as proof of authorship of medical images. Zero watermarking, in principle, seemed to be promising to achieve this objective. We have done intensive testing of several zero watermarking algorithms. The results are summarized in this paper.Masaryk University, Czech Republic, develops and runs a system that provides new platforms for very efficient regional cooperation in the field of medical imaging. Currently, the system enables secure communication between hundreds of health care institutions, mostly from the Czech and Slovak Republics.The communication capabilities of the system make it possible to transfer highly sensitive patient image data between different medical devices or applications located in health care institutions, which may be far from one another.Supportive technology allows defined interactions among the external environments involved. The main stakeholders are specialized health care institutions, general and university hospitals, individual radiologists, universities and research centers, ICT services providers, etc. One of the key issues is the expression of authorization boundaries and the enforcement of access rights to distinguish those who may use individual datasets and those that must not.An individual image examination  generated by acquisition modalities, such as computed tomography, magnetic resonance, etc., is composed of a series of individual medical images. They include personally identifiable information  Unauthorized disclosure or unauthorized modification of health-related data affects that particular patient  as well as the health care institutions who, according to regulatory laws, hold accountability for the data processing. The information security requirements can be expressed as the confidentiality, integrity, and availability of clinical data and related processes. The processing must also be in line with relevant legal, ethical, and contractual requirements. Those regulatory laws and policies are becoming very strict in most countries these days.The environment (processing) for which we evaluate the suitability of the watermarking schema can be defined as the processing taking place over a set of image objects originating from routine image examinations and retrieved from operational PACS systems of cooperating health care institutions. The selection of specific series or individual images from the initial imaging examination like CT typically disrupts attributed digital signature. There is a necessity to share highly sensitive data. The set of objects is shared (modified) within the community of legitimate users and controlled by its owner. The trust between the owner and other parties can be grounded on privacy regulations or research/business contracts.The typical examples are cooperating research activities over clinical data, i.e., sharing the data with trusted third parties, where the integrity protection, authorship, and other security issues are of critical importance. Hospitals and medical research centers form a unified computerized environment these days where traditional diagnosis, treatment, and research activities intertwine.Appropriate watermarking schema enables different kinds of information to be treated in different ways. It can encode the knowledge of the owner and the identity of the third (trusted) parties, and then, for instance, reveal the violating the illegal sharing with non-trusted parties. The supportive rules can be set up, then enforced via proposed watermarking schema, and this way prevent unwanted disputes over the source data, the integrity of its essential parts, protection of highly sensitive information attributed to the image, research results, etc.generation of the introductory watermarked image study enabling legitimate participants to process the watermarked image studyparts of the watermarked image study can be provided with additional information (modified) during the cooperating activitiesextraction of the hidden information from the watermarked image by authorized usersevaluation of the quality of the extracted watermarks and, thus, the consistency of the intended processing Typical usage of the proposed watermark schema for the above-defined processing consists of some combination of the following steps:prevention of unauthorized modification of regions of interestthe ability to identify the conducted clinical study or identify patients who participate in the imaging study, integration with image information, avoiding separationthe possibility of hiding required informationthe ability to provide the critical parts of an imaging study in its original quality.The critical features of the proposed watermarking schema relevant to the above-defined usage scenario:A traditional digital watermark hides information about the owner or creator of an image or images somewhere within that image. This hidden information can subsequently be used for many purposes: maintaining the integrity of the image, detecting deliberate or accidental tampering, protecting copyright in the data, etc.Regarding medical imaging, watermarking schemas such as zero watermarking, reversible watermarking, and lossless watermarking  in particular—as well as some of their interconnections—seem to be highly relevant. In most cases, the degradation of medical images is unacceptable due to the high image quality requirements of diagnostic processes. So-called zero watermarking can successfully solve these specific requirements.The main advantage of the zero-watermarking method in medical imaging is that the watermark is not embedded in the image itself so, unlike traditional watermarking techniques, the watermarking process does not apply any modification to the image, thus avoiding any distortion of the image. Hidden features are extracted from the host image and combined with the watermark  and then encrypted, and a key is produced. The secret share must then be kept in a trusted authority for future watermark extraction. So, the extraction of internal representative feature information from the image data is the critical phase in the zero-watermarking approach.The zero-watermarking algorithms being reviewed were evaluated using samples taken from suitable datasets of medical image examinations. We especially focused on the detection of malicious tampering, such as the addition or removal of objects of interest from the critical medical image (which can be in some situations even life-threatening). Some medical image examinations  produce a series of very similar images. The crucial problem considered in this paper is how to solve the authorship issue in the case of very similar but different images  and the case of one image and its modified copy.According to the current state of our research, it is practically impossible to find a suitable solution matching all the requirements and constraints relevant to this particular application area. We will only succeed if we focus on some particular services or applications, their specific features, and crucial security issues. Regarding data from medical image examinations, these issues are the authenticity and integrity protection of linked series of images.Security issues such as accepting forged content as if it were legitimate represent one of the most serious problems in the area of medical image processing. This kind of consideration in particular shapes our research. In general, it is evident that to develop a perfectly fitting watermarking system is not possible. But another question to be resolved is an assessment of particular real scenarios  and their practical achievability .The main goal of this paper was to answer the following questions. First, can an appropriate zero watermarking method be regarded as a suitable prospective one for checking the integrity of medical image examinations? Second, can an appropriate zero-watermarking method be regarded as a prospective one for checking the authorship of medical image case studies? Specifically, could suitable watermarking methods reveal some referential threshold to identify the required integrity or authorship changes?From a variety of available medical image datasets, we have selected cross-sectional CT (computed tomography) scans of abdomens with diagnosed tumors.CT scanners currently represent one of the busiest acquisition modalities. A typical CT examination, also called an image study, consists of hundreds or even thousands of individual slices (images), which are then organized into a specific series. Each image slice, depending on the type and configuration of the particular CT scanner, represents 1 to 10 mm of the patient’s tissue. Images are mostly displayed and diagnosed individually or used to generate a three-dimensional picture of the patient’s body. CT scans enable the efficient identification of diseases of the various body regions, such as revealing possible tumors. They display far more complex information compared with X-ray examinations.All the medical image data necessary for this research was selected from the long-term archive of anonymized image examinations developed to support of specific research activities. Its content was originally gathered from the Clinical PACS (Picture Archiving and Communication System) of health care institutions from the region.We have implemented four promising zero-watermarking methods. The testing was conducted over three types of datasets representing the likeliest adverse scenarios.The first type represents the manipulation of critical medical content such as adding, removing, or replacing some of the critical parts of the tissue, organ, or tumor. We used a graphical editor to gradual substitute of tumor by copying nearby healthy tissue in the CT image. After removing whole tumor, we started removing firstly small organs and secondly large ones.The second type represents the case of replacement of the key images in the series with nearest and most similar ones belonging to the same patient.The third type is similar to the second one but utilizes appropriate images from the same part of the screening of another patient.The resulting graphs visualize the computed similarity dependences of series of intentionally manipulated images and a series of relevant original ones. The images are arranged into sequences according to a reference PSNR  metric .Considering the selection of a particular acquisition method (CT) and selection of a particular disease (tumor), it is not possible to generalize the results about the appropriateness of investigated zero-watermarking methods into other domains of medical imaging.Necessary context, including related terminology, has been described in detail in . The comUsing these two inputs , we can compute two outputs: a public share and an ownership share. Nevertheless, the ownership share contains enough information to prove that it was computed from the original image and the watermark. The ownership share is used for internal computation only. It should be stored in a secure and trusted place, e.g., dated and signed by a public certification authority.Later on, the ownership share serves for image authorship approval. If we meet an image we suspect to be ours anywhere, we can check it with the following principle illustrated in Fig. The discussed watermarking algorithms differ in exactly how the ownership share is computed from the original image and the watermark. A detailed description of the main zero-watermarking algorithms is in the following subsections.For simulations and testing purposes, we selected four zero-watermarking methods with different security approaches. These methods represent the wide-scale state of the art in the field of zero-watermarking methods in medical imaging.k-level Dual-Tree Complex Wavelet Transform (DT-CWT) [The first method, “Robust image watermarking scheme using visual cryptography in dual-tree complex wavelet domain”, uses as its input the original image, a watermark, and a secret key. . For tra(DT-CWT)  is used.The second method is “A Zero-Watermarking Scheme using Discrete Wavelet Transform” . As an icompleted local binary pattern method [The next method selected is “Discriminative and robust zero-watermarking scheme based on the completed local binary pattern for authentication and copyright identification of medical images” . This men method . As inpuA QR Code Based Zero-Watermarking Scheme for Authentication of Medical Images in Teleradiology Cloud [singular value decomposition [The last method examined is gy Cloud . It usesgy Cloud . Low-freposition  is appliTo demonstrate the outcome of our research, we have selected representative of various watermarking methods with different ways of watermark insertion and representing a different class of zero-watermarking algorithms commonly used in medicine. As will be observable from the results below, all zero-watermarking algorithms except one provide similar results. Due to our long-term cooperation with Masaryk Memorial Cancer Institute, the algorithms examined were used on (anonymized) CT images of patient with tumor recommended by physicians from this institute.During our testing of zero-watermarking methods, we conducted a lot of simulations and comparisons.In the first phase, we focused on observing the behavior of individual zero-watermarking methods in case of modifying the secured image see Fig. .Fig. 3PaThe result of this phase is shown as a graph in Fig. During this progress, we observed the behavior of the particular watermarking methods. In other words, we reduced the resemblance of the secured image and the modified image from which watermark is extracted (the PSNR), and we observed the similarity of the embedded and extracted watermark NCC . From tIn the next phase, we compared characteristics of watermarking methods in the instance of exchanging watermarked images with neighboring CT images of the same patient. The graph in Fig. These methods are therefore inappropriate to protect authorship when exchanging the watermarked image with neighboring images. This is because it is not possible to recognize if the medical image was only modified (and is owned by his author), or if it has been replaced with a different image of the same patient.In the final stage, similarly to the previous phase, where we exchanged a former secured image with neighboring images, we exchanged a formerly secured image with an image of the same body part of a totally different patient. As in the previous phase, similarity of the secured and exchanged images is low , the NCC values of the inserted and extracted watermarks were rather high, despite the low similarity of the secured and changed (attacked) images.It is obvious from Fig. The NCC itself is only an image similarity measure. If the NCC of inserted and extracted pair of watermarks is high, it still does not guaranty that the image the watermark was extracted from is a derivative of the original. It only expresses our belief or plausibility of being so. Currently, NCC above 0.7 is taken as the touchstone whether it is tested image suspected to be a derivative of the protected one. Proper determination of the threshold or possible two (soft and hard) thresholds is subject to further study. The Zero CLBP CliclePartition VC method comparing with others seems to be the much more sensitive in distinguishing modified picture from a completely different one.The presented approach represents a suitable solution for protecting the integrity, and at the same time, enabling controlled sharing in medical imaging. It allows the detection of breaches of personal data protection obligations. For the case of dispute over the ownership of the imaging study, the owner’s identity can be invisibly inserted into the image. It enables one to distinguish individual copies of the imaging study (by embedding specific part of the watermark per legitimate user), and this way identify the potential originator of the illegal copy. Some highly sensitive information may remain hidden from unauthorized participants.The important thing is that some modifications or the addition of trial relevant information are permissible. All the changes can be then (for the assertion of authenticity) verified by the entitled party. The schema can distinguish the level of modification, or whether any took place at all, and this way provides the desired trade-off in the protection of shared medical content. Just binary information provided by digital signature techniques is its main shortcoming when compared with watermarking.Embedded hidden information can indicate the ownership, can contain some object-specific information like patient identity (pseudo-identity), or convey conditions of legal usage  via embedding a unique mark for each legitimate user. The secret key, which is necessary to recover the embedded information, can be shared within the research community or be under the sole control of the data owner.For the introduced usage scenario, an appropriate watermarking schema provides the desired flexibility. The advantage of watermarking over the digital signature in the collaborative environment, where the medical images are subject to legitimate modification , is visible.This article deals with testing zero-watermarking methods to ensure the authorship and integrity of medical image data. This protection is necessary, for example, when sharing images for educational or scientific purposes. Securing medical image data with zero-watermarking methods has many undisputed benefits: it does not modify secured data, and the participation of trusted authority, the use of timestamps, and further processing of secured data are all allowed—they are not encrypted or modified.We conducted three types of tests as simulations of attacks: modifying the secured image itself, replacement of the secured image by neighboring images in CT studies, and replacement of the secured image by images of the same part of the body, but a different patient.We concluded that zero watermarking is suitable for checking the integrity of digital medical images, but it is not usable for securing their authorship. This is because generally, zero watermarking is not able to recognize differences between an image modified by an attack intended to steal its ownership and a completely different image.The zero-watermarking algorithms used for this task generate too many false-positive alarms. Zero watermarking is not able to reliably enough distinguish a modified image belonging to the author from somebody else’s similar image. Especially in the medical field, it is not capable of distinguishing images of the same part of the body originating from two different patients.On the other hand, zero-watermarking algorithms proved a good reflection of the degree of image modification, so they probably could be used as a measure of image similarity. The utilization of zero-watermarking algorithms for this purpose needs further study and testing.


B. longum subsp. infantis, which has evolved to colonize the infant gut, is a safe and ecologically-sound approach to restoring the gut microbiome of infants born by c-section.There is a burgeoning literature highlighting differences in health outcomes between babies born vaginally and by caesarean section (c-section) This has led to the suggestion that infants born by c-section may benefit from vaginal swabbing/seeding. Here, we discuss from an ecological perspective that it is gut-adapted, not vagina-adapted microbes that are likely to take up residence in the gut and have the most beneficial impact on the developing neonate. Further, we caution the practice of ‘vaginal seeding’ may be potentially unsafe and also give parents and health professionals a false sense of action in restoring the infant gut microbiome following c-section. Instead, we argue that restoring  B. infantis.Restoring the gut microbiome of infants delivered by cesarean section with  There is a large body of literature indicating that the long-term health outcomes of babies delivered by caesarian section (c-section) are different than those delivered vaginally. The largest single study of this kind included 1.9 million infants born between 1977 and 2012. The analysis showed significantly increased risks of asthma, juvenile arthritis, inflammatory bowel disease (IBD), immune deficiencies and leukemia in the c-section group compared to babies delivered vaginally over the same time period , the nutrients available (dietary and host derived glycans), and the birthing process itself, the most obvious seeding source of the infant gut microbiome is the gut microbiome of the mother. During a vaginal delivery, the baby's head presses on and flattens the mother's colon so that is very common for the mother's stool to be expelled to some extent. The proximity of the vagina and the anus and the optimal fetal position for birthing  facilitates the likelihood of maternal-infant microbial transfer  as it has several unique gene clusters to capture, transport and internally metabolize all of the approximately 200 different HMO structures . Thus, during this time, the breastfed infant gut microbiome is mainly shaped by the only glycans reaching the infant's colon, namely human milk oligosaccharides (HMO). The importance and role of these HMO is underscored by their abundance in human milk (15% of the energy content) and the inability of these compounds to be metabolized by the infant  in early life, we argue that scientific and medical focus should be placed instead on the rational design and implementation of strategies to reestablish the dominance of bifidobacteria in to the gut microbiome of infants, which shows the most promise in having a positive impact on life-long health outcomes (Duar et al. B. infantis to the infant gut microbiome represents one such approach that simply reestablishes the natural system of protection.In conclusion, and viewed from an ecological and evolutionary perspective, it is gut-adapted, not vagina-adapted, microbes that are likely to take up residence in the infant gut Fig.  and, the


The globus pallidus internus and the subthalamic nucleus are common targets for deep brain stimulation to alleviate symptoms of Parkinson's disease and dystonia. In the rodent models, however, their direct targeting is hindered by the relatively large dimensions of applied electrodes. To reduce the neurological damage, the electrodes are usually implanted cranial to the nuclei, thus exposing the non-targeted brain regions to large electric fields and, in turn, possible undesired stimulation effects. In this numerical study, we analyze the spread of the fields for the conventional electrodes and several modifications. As a result, we present a relatively simple electrode design that allows an efficient focalization of the stimulating field in the inferiorly located nuclei. The exact mechanisms of deep brain stimulation (DBS) for Parkinson's disease and dystonia treatment still remain unclear. To explore these mechanisms, often experimental approaches involving stimulation in rodent models such as 6-hydroxydopamine treated rats and genetically dystonic hamsters are used. However, significantly smaller dimensions of their brain structures, if compared to human brain, constrain the implantation possibilities. In case of the entopeduncular nucleus (EPN), the equivalent of the globus pallidus internus in rodents, or the subthalamic nucleus (STN), even the exact targeting leads to a considerable neurological damage inflicted by the electrode lead. Therefore, the stimulating electrode is often placed cranial to the targeted nucleus. However, the resulting proximity of the electrode to the thalamus and the internal capsule (IC) could cause undesirable effects of the stimulation, which must be avoided, as they would distort the experimental results, whose interpretation thus becomes very difficult. The primary goal of this study is to evaluate the theoretical applicability of several electrode designs for the stimulation of the caudally located nuclei and suggest an optimal solution for a precise focalization of the electric field in the target.For DBS, the electric potential distribution in brain tissue can be approximated by the electro-quasistatic formulation of Maxwell's equations . In case of the current-controlled stimulation, the electric potential distribution can be scaled to match the required current using the linearity of (1). In this study, we simulate a 60 μs 60 μA rectangular pulse delivered by a bipolar electrode implanted 0.4 mm above the center of mass of the targeted nucleus.The Dirichlet boundary conditions for (1) are given by the potentials on the exposed electrode contacts, while the rest of the external surfaces are assumed insulating (∇E| = |∇E|) as described in Åström et al.  are widely used for DBS in rodent models. However, for cranial implantations, where the electrode is not placed in the target, their application may raise the problem that current will bypass the target nucleus to a significant extent. In this particular case, the electric field is shifted upwards which can cause additional direct stimulation effects in the thalamus . This phE| metric, stimulation with SNEX-100 shows the expectedly lowest targeting: the size of the outer contact and its proximity to the core contact create the electric field large enough to expect the neural activation occurring along the whole current path. The same is observed for CEAX-100, but since the contacts are located more closely, the activation in the non-targeted regions is reduced. One possible downside is that due to the sharp tip, this electrode design will create relatively large current flow at this site, which may lead to additional damage due to electrophoresis effects or outright coagulation. The modified design with the spherical rounding shows a distinctly better performance: the remoteness and the large surface of the outer contact diminish the electric field away from the core contact, thus preventing the neural activation in the superior brain regions, in this case the ventral portion of the thalamus (including the zona incerta). However, for these three electrodes, the predicted activation in the target is negligibly small (3 for the spherical rounding and the blunt end, respectively. For the EPN, the corresponding values are 0.371 and 0.602 mm3. At the same time, the blunt end core contact, insulated on the sides, generates even lower fields above the target. A more conservative but still compelling improvement is estimated by |∇·E|. In general, this metric predicts a lower activation: 0.045 and 0.117 mm3 in the STN and 0.218 and 0.318 mm3 in the EPN for the spherical rounding and the blunt end designs, respectively. This leads to the conclusion that while a relative performance of the electrodes can be assessed with the electric field metrics, accurate predictions of the neural activation require application of detailed neuron models. It can be also noted that for all electrodes and both field metrics the targeting of the EPN is more efficient, which is explained by its smaller lateral extent in comparison to the relatively oblate shape of the STN.The analysis reveals a distinct difference in performance among the electrodes see . For |E|ly small , especialy small . For comAs previously mentioned, the DBS electrode not only stimulates neural structures, but also inflicts mechanical damages on brain tissue. For the implantation positions considered in the study, the damage occurs mostly in the cortical and the thalamic areas. Its extent in the ventral portion of the thalamus differs depending on the electrode type, and this factor must be considered by researchers. Among the presented designs, the electrode with the blunt end is expected to inflict the largest damage. This is not necessarily the worst case scenario: in principle, a limited neurological damage may lead to more predictable effects rather than an undesired fragmentary stimulation.in vitro and in vivo studies.In this study, the diameter of platinum/iridium core for the modified electrodes was set to 0.240 mm. Depending on the target dimensions, the parameter can be adjusted, but it is important to keep in mind that additional neural damage can occur if a certain charge density per phase limit is exceeded (McCreery et al., In conclusion, we propose two improved designs optimal for focal stimulation of small rodent brain nuclei—a spherical tip likely inflicting less damage, but also resulting in about 50% less focal stimulation, and a relatively blunt one offering the arguably best focal stimulation at the cost of slightly larger tissue damage. In either case, the manufacturing advantage may be seen in the fact that the reference electrode, i.e., the outer contact, does not need any sophisticated design.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The study design and the simulations, as well as the preparation of the manuscript were conducted by KB. UR supervised the study, reviewed, and edited the manuscript. RK provided an expert opinion on the biological and anatomical aspects and reviewed the manuscript. All authors contributed to the article and approved the submitted version.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Superconducting links are an innovative solution for bulk power transmission, distinguished by their compact dimensions, high efficiency and small environmental footprint. As with any new technology field, there is a large amount of design possibilities for such links, each of them having a profound impact on the system configuration. For instance, changing the material can imply a change in the working temperature from 20 to 70 K and has consequences on the maximum link length. This article presents the dichotomic decision possibilities for the optimized design of a high-power superconducting link, focusing on some of the key components of the cable system. The complex design optimization process is exemplified using the European project Best Paths, in which the first 3-gigawatt-class superconducting cable system was designed, optimized, manufactured, and successfully tested. Superconductivity occurs in materials that can transmit electricity without losses below three characteristic thresholds: a critical value of the temperature, a critical intensity of the magnetic field, and a critical current density. Discovered more than 100 years ago, superconductivity has found successful application in both research and industrial contexts, for instance, in particle accelerators and medical imaging devices  ushered Due to their high efficiency, compact size, and reduced environmental footprint, superconducting power cables have generated increased interest in recent years . These pIn the past decade, a growing number of projects related to superconducting cables of various lengths and capacities have been constructed or become operational worldwide . A promi2) [2 wires in kilometric lengths [2 are more complex and more expensive. The benefits and drawbacks of these two key components of the cable system, superconducting material, and cooling system need to be carefully weighed when designing a new cable and optimizing the system performance.Nevertheless, widespread use of such superconducting systems for power transmission has been hindered by the high costs of the ceramic-based superconductors and their complex manufacturing process. A promising alternative explored in recent years is represented by the simple binary compound magnesium diboride (MgB2) , which i lengths . Unlike Road vehicle traction system : three oAirplane engines location : severalThermal cycle cold sink in power plants : a dry cWindmill morphology : the thrThe optimization process in the design of complex systems is not simply a continuous mathematical function, but goes through a dichotomic decision tree that has not yet been reported for the field of superconducting links. In other engineering fields, there is a multitude of examples of dichotomic decisions related to the design of complex systems:This work analyses the design possibilities that usually appear in a new technology field—in this case high-power superconducting links—and that can be limited by optimization within the traditional framework of continuous variable analysis. To avoid limitations and achieve an optimal design, dichotomic decisions are introduced, which can bring about a substantial change in the system configuration. We exemplify this approach through an in-depth description of the dichotomic decision-making process undertaken for the recently finished European project Best Paths , which dThe article is divided into two main sections. Available technologies for high-voltage direct-current (HVDC) transmission up-to-day include overhead lines , insulated cables—underground (UGC), or submarine (SUB)—gas insulated lines , and superconducting cables (SCC), located underground.OHL are the backbone of transmission grids, with more than one century of service experience. Generally, except in dense urban states like Singapore, buried technologies represent less than 10% of the installed length, but most of the new infrastructures. GIL and SCC are still niche projects.OHL are well-established at very high ratings for very long distances with several commissioned and operational ±800 kV links, particularly in China, Brazil, and India. For instance, the Zhundong-Wannan link in China transmits up to 12 GW at ±1100 kV across 3320 km . The lonFirst of all, the technology selection for new infrastructure depends on the macro-environment to cross, especially according to the nature and size of the obstacles to cross. Common options are highlighted in  for high difficulty), depending on whether advantages or disadvantages are described. Furthermore, these various aspects are addressed in detail below, providing a state-of-the-art overview that highlights the complexity of the decision-making process.In addition to the criterion related to obstacles, The visual impact of transmission infrastructures may raise strong local opposition. This mainly concerns OHL, as the towers of the corridor become taller and wider with increasing transmission voltage. Buried technologies are often a condition for much better public acceptance and can significantly reduce the duration for getting the necessary administrative permits .Most of the existing GIL are located outdoors, but the conduits can be buried or installed in tunnels. SCC are generally installed in buried ducts, with only the terminations visible at the end of the link.Insulated solutions are designed to contain the electric fields and are much more compact. However, neither buildings nor trees can be added above the buried cable route.The required strip of land includes not only the footprint of the power link itself, but also a service strip for eventual maintenance and repair. In any case, the expected footprint during the civil engineering must be extended for temporary storage of the excavated material .OHL may be damaged by storms, icing, sticky snow. In areas where these weather conditions are identified and recurrent, it can be preferrable to employ buried technologies. Only the equipment located above the ground in substations would then be affected. Insulation coordination is organised to avoid lightning damages in all power grid sections, as well.SCC systems can be considered like any regular underground technology.The current rating of a resistive transmission link always depends on at least one thermal criterion, because of the Joule losses, which heat the conductor and contribute to its expansion. Moreover, a maximum critical temperature at the outer surface may be required for buried systems, to avoid soil drying and thermal runaway.The bare conductors of OHL are exposed to solar radiation and cooled by natural convection and wind. The dilatation of a span between two towers brings the lowest point closer to the ground. The regulations impose a safe distance for people.The cables insulated with impregnated paper or polymeric materials must not overheat beyond a maximum temperature, above which ageing and breakdown may occur.The intrinsic cryogenic cooling of superconductors makes the SCC independent from the surrounding thermal environment. The current rating is not affected by high ambient temperatures, and no heating is generated to the surrounding soil.The crossing of mountains is technologically easier with OHL, but results in a strong impact on the surroundings. Tracks are built to access the tower locations; helicopters can be used to carry steel angles. Trenching may be complex in soils with rocks or slopes. Tunnels may be an expensive solution.When SUB cannot be buried, rock damping techniques ensure their protection.For SCC, the management of elevation must also be considered due to the pumping of cryogenic fluid.Mid-span tension joints provide electrical and mechanical continuity of the OHL conductor. Insulated cables are connected by joints that reproduce the continuity of each of the concentric components.Factory joints are prepared ashore for SUB, while field joints are manufactured for other technologies. The use of prefabricated or pre-moulded joints has brought a significant growth to UGC systems.The joining of SCC systems is performed by means of a manual process.The repairing of OHL is easier, with visual inspection and direct access to the bare conductors both possible. A preliminary fault location is required for buried technologies, followed by digging to prepare a repair joint. The use of ducts gives the possibility to replace the damaged section by a spare.The repair of SUB links may require several months and several tens of millions of euros .The repair joint of SCC systems is made more complex by the additional reconstitution of the thermal insulation and associated vacuum loss.The possibility to transmit bulk power in the same link may be a drawback in case of a breakdown. The (n-k) rule of parallel circuits per phase is applied to avoid a total power outage. OHL towers often support several circuits and bundles of conductors.A meshed grid can transfer the load of the failing link to other links, a 3 GW limit often being considered by the transmission system operators. This criterion must be taken into account for SCC systems, whose power rating may exceed this limit. Their intrinsic capability may be then restricted by operating considerations.OHL are exposed to climatic conditions and corrosion. Frequent visual inspections and tower painting are scheduled.Very low maintenance is required for UGC and SUB systems, while GIL and SCC have fluids under pressure and associated monitoring and maintenance operations.Electric fields are characteristic of OHL, while magnetic fields are generated by all the technologies under consideration here. It must be noticed that the possible health effects of electromagnetic fields are very different from the static fields generated by HVDC systems ,21. TherA peak of the magnetic field is observed for UGC above the cable route, but in a very narrow corridor, while a measurable value remains at 100 m for OHL. By design, electromagnetic fields are negligible for GIL and SCC.Economic considerations are crucial for the selection of the technology. The investment cost (CAPEX) includes the cost of the components, the commissioning tests, but also the delivery, installation on site, and civil engineering. The operating cost (OPEX) includes the cost of monitoring and maintenance, repair, losses. The selection of the technology needs to strike a good balance between CAPEX and OPEX. An attractive CAPEX may lead to an expensive OPEX, due to excessive maintenance operations or equipment replacements. From a technical point, only SCC systems have no electric losses, the remaining technologies exhibit Joules losses depending on the instantaneous current value, which impacts significantly the OPEX. However, the cooling system of a SCC consumes electric power to maintain the operation at cryogenic temperature. In fact, this is the main operating cost of a SCC system. It is difficult to rate the technologies generically, because each project must be assessed separately, accounting for the specific context. It can be noticed that the most expensive projects are those that end up not being realized due to excessive delays or cancelations. Some niche cases can then provide very valuable solutions; for instance, SCC systems can save investments on transformers and substations, due to their lower rated voltage level.The environmental impact of a transmission system is increasingly considered for the selection of the technology. It can be assessed with a life cycle analysis (LCA) approach. Such studies  show forThese considerations illustrate the complexity involved in the technology selection for a new HVDC power link. In the electricity grid, a combination of the various HVDC technologies is generally used for power transmission along hundreds of kilometers. The different segments using successively one of these technologies are connected in series to build up power links running from remote energy sources to consumption centers in large urban areas.As discussed above, each HVDC solution has benefits but also limitations according to the specific application. The selection of the best technology for each link segment is strongly dependent on the local installation conditions. For example, the OHL technology is well adapted and accepted in sparsely populated areas, but often rejected in western Europe, in particular in suburban areas. By contrast, given its very small footprint and low environmental impact, the SCC technology is very well adapted to enter or cross large cities or protected areas, but of less interest for crossing large empty areas.The OHL, UCC, SUB, and GIL technologies have already been installed and proven their added values in electricity grids. Only high-power SCC have not yet been field tested in the real grid. This was the key motivation for the study of HVDC superconducting cable systems in the Best Paths project.Generally, an HVDC superconducting cable system is operating at high voltage with a range of possible currents exceeding 3 kA. Below this current level, the conventional resistive cable technology is more able to meet the grid’s requirements and can be used instead. As seen in ○Superconductor;○Cryostat (cryogenic envelope), housing the cooling fluid needed to maintain the superconductor temperature;○High-voltage electrical insulation;○Cryogenic terminations and joints;○Adequate cooling devices connected to associated power and fluid supplies for the auxiliary equipment .Essentially, a superconducting cable system consists of the following key components, schematically illustrated in The superconducting material is directly wound on a central former that can be practically made with copper cable. This copper core helps to protect the cable during a possible short circuit or fault, where a huge current could suddenly overwhelm the system. To ensure the voltage insulation between the pole and ground, a thick dielectric material is required. This insulation could, for instance, be made out of polyethylene layers and be located outside the cable cryostat. In this case, the insulation operates at room temperature in a so-called “warm dielectric” design . An alteThe cable assembly is placed into a cryogenic envelope with low thermal losses, which maintains the adequate cryogenic operating temperature and prevents thermal exchanges with the surrounding environment. In addition to the cable itself, the system includes two terminations to connect to the electricity grid, some junctions associated with thermal shrinkage management to extend the cable length, and from place to place several cooling systems or refreshing units to recover the operating temperature.From the considerations presented in Before proceeding, a brief summary of the Best Paths superconducting project is provided. The project focused on validating HVDC superconducting links operating at the multi-gigawatt level . In a tiBest Paths had an extensive preparatory phase, which encompassed the specification, development and optimization of the main system components. Some of the key considerations elaborated in this preparatory phase follow a dichotomic decision pattern and are incorporated below. Most of the presented tree branches are new and have been explored during the decision-making process. Note that the choices made within Best Paths were partly determined by the scope of the demonstration and the available technologies, as the project aimed for realistic solutions that could be readily implemented.The selection of the superconducting material has an important impact on the cable design and the choice of the remaining system components, as presented below.Today three superconducting materials are available in sufficient quantity with high enough performance to be considered for power cables. Their main characteristics and costs are reported in 2, available in round wires. They benefit from the high-yield and low-cost PIT process [2.The third material is MgB process , and do  process , at even2 was identified as a good candidate, assuming that it is possible to reliably maintain the low operating temperature (<25 K) at an acceptable price. This choice is reflected in the decision tree of As HVDC superconducting links are foreseen to transmit a high current (>10 kA) across hundreds of kilometers, the use of HTS tapes for such long links was not considered as viable at present. This shall be definitely reconsidered when their cost becomes affordable. Combining the HTS tapes with more expensive cooling fluids such as helium or hydrogen is currently not considered realistic for practical applications, and was therefore not included in the decision tree. Due to its low cost, MgB2 cable, the inlet temperature of the fluid should be set at a lower level, typically at around 15 K. The different options for the cryogenic fluids are illustrated in In a cable system, the temperature of the cooling medium along the link increases between two cooling machines, due to the heat inleak through the cryogenic envelope. To ensure a temperature of 25 K on the MgB2) and air were considered but rejected, due to the extremely high number of cooling systems required to be installed along the link, and to the very long cooldown, which is only possible by thermal conduction. For a cable system a circulating fluid is preferred.Solidified low-cost cryogen fluids such as nitrogen (N2), and neon (Ne). Their physical properties are presented in The only practical fluids at this temperature are helium (He), hydrogen . As shown in 2 shifts the temperature of the shield from 76 K to 105 K.The first option requires the management of an additional fluid. This fluid could be a neutral fluid such as liquid NFurthermore, large industrial liquefaction stations with their associated auxiliaries  have been in operation for many decades in harsh environments , which demonstrates their reliability and robustness. The use of LNG as a thermal shield fluid also offers the possibility to transfer both electrical and chemical energy along the same line. Moreover, a number of distribution gas points could be installed along the link, building a new gas network that will increase the profitability of the system. For a safe use, the association of LNG with the gigawatt-level powers of an electrical transmission cable needs to be carefully validated and certified by authorized bodies.2 solidifies. Naturally, the fluid selection depends on the cooling medium of the superconducting cable, which also limits the design possibilities for the electrical insulation, as discussed in The second option involves the use of the return flux of the superconductor coolant and would simplify the management and installation of the system. It offers the possibility to operate at a lower temperature than 65 K, where liquid N2 is obtained by the evaporation of liquid H2 from the superconducting cable. As presented in 2 is once again the best fluid with regard to thermal properties. However, as already mentioned, the risk management of its flammability needs additional thorough investigations.Gaseous HThe use of warm gaseous He extracted directly from the end of the superconducting cable channel is also possible. However, this solution has the drawback that it increases the global He inventory of the cable system by at least a factor of 3. While this may be a realistic option for medium-length links, it could significantly impact the cost of the system and possibly the available global He resources for very long links.2 was selected as the thermal shield fluid for Best Paths project; this second cryogenic fluid will also contribute to the high-voltage insulation of the cable.While the discussed options are promising and must be deepened, liquid NBest Paths aimed to demonstrate the feasibility of an HVDC superconducting cable system able to transmit electric powers higher than 3 GW. The 320 kV operating voltage was chosen to facilitate the insertion of the superconducting cable into existing grids, considering the currently deployed grid technologies such as converters, breakers, etc. Consequently, the cable system had to be tested at nearly 600 kV, in order to meet the recommendations for testing HVDC cables from Cigré .This high voltage (HV) level impacts significantly the design, in particular the cable diameter. The thickness of the HV insulation layer is proportional to the testing voltage, and inversely proportional to the voltage breakdown strength of the material and the diameter of the cable conductor. To meet the Cigré testing protocol of a 320 kV class cable insulated by a material with a voltage breakdown strength of 37 kV/mm , the insAs already mentioned, superconducting cables are designed for electricity transmission at high currents. In order to keep the overall diameter of the cable as small as possible, it is worth reducing the voltage class in future, while increasing the operating current to keep the gigawatt powers .The “warm dielectric” and “cold dielectric” insulation concepts were introduced in In the “cold dielectric” design, the employed material needs to be sheet-structured to avoid cracks in the HV insulation layer, due to differential shrinkage during cooldown . Appropr2, paper can be selected as the insulation layer, while for gaseous He polyimide tapes are recommended due to its poor breakdown voltage. Furthermore, the 10 kA conductor composed of MgB2 wires has an outer diameter of 10 mm. For a material with a dielectric breakdown of 37 kV/mm, the insulation thickness for a 320 kV class system is estimated at about 110 mm, due to local electric field strength. This solution is not realistic. However, decreasing the voltage to a 100 kV class, for example, reduces the insulation thickness down to 8.5 mm, which becomes acceptable. As the Best Paths system is specified to operate at 320 kV, the solution of a cold dielectric located in the inner cryostat was not chosen for the project . Two distinct approaches can be used for this purpose :The “fauA fault-tolerant design was chosen for Best Paths, and the behavior of the cable conductor was investigated for an over-current of 35 kA lasting 100 ms. This level of fault current is a representative value required by transmission system operators for a long HVDC cable link. The diameter of the copper core can be chosen according to the level and the duration of the fault current. To determine the optimal diameter, it is essential to evaluate the maximum temperature reached, so as to avoid any damage by overheating. To this end, a multi-physics model has been developed taking into consideration the thermal and electrical properties of the temperature-dependent materials. For the chosen Best Paths design, the simulations show that the temperature does not exceed 90 K during and after the investigated fault .In general, the value of fault current should be calculated considering the real grid architecture, in particular, the power available and the impedance of all the circuits connected together.Apart from the engineering and practical aspects discussed so far, the requirements for an HVDC superconducting cable should also consider other aspects that impact the technology selection. For long links, the selected cable design should be manufacturable on a large scale over long lengths, with a minimal number of joints. During the installation phases, the cable should be transportable to the different sites along the link, and efficiently laid and buried into the ground. The duration and impact of civil engineering should be kept as limited as possible, in order to improve the obtaining of administrative authorizations. All required rules and regulations should be followed, while also addressing the concerns of the affected local actors. Once in operation, it is crucial that the cable system be robust, reliable, and maintainable.This article presents the application of a dichotomic decision process to achieve an optimized design for an HVDC superconducting link. This complex process is exemplified using the European project Best Paths, in which the first 3-gigawatt-class HVDC superconducting cable system was manufactured and successfully tested.A number of different conceptual and technological options for the practical realization of high-power superconducting links are described in detail, even if they were not feasible within the scope of Best Paths. To begin with, superconducting links are placed into the landscape of available HVDC technologies in a detailed overview. Afterwards, the main part of the article focusses on the dichotomic possibilities related to some of the key components of the cable system, such as the superconductor, cooling fluid, cryogenic envelope, thermal shield, and high-voltage electrical insulation. The associated analysis should provide a good basis for designing a variety of configurations for superconducting links.Superconducting links represent a technically realistic solution for bulk power transmission and could contribute to the necessary decarbonization of our society by reinforcing and increasing the efficiency of electricity grids with very limited environmental impact. Moreover, a whole panoply of concepts and technologies exist that can still enhance their efficiency and carbon emission footprint. Beyond electricity transmission, the use of superconducting cables also opens up the unique and promising possibility of simultaneous transport of two energy carriers, by combining both hydrogen and electricity.


The current diagnosis of Congenital Heart Disease (CHD) in neonates relies on echocardiography. Its limited availability requires alternative screening procedures to prioritise newborns awaiting ultrasound. The routine screening for CHD is performed using a multidimensional clinical examination including (but not limited to) auscultation and pulse oximetry. While auscultation might be subjective with some heart abnormalities not always audible it increases the ability to detect heart defects. This work aims at developing an objective clinical decision support tool based on machine learning (ML) to facilitate differentiation of sounds with signatures of Patent Ductus Arteriosus (PDA)/CHDs, in clinical settings. The heart sounds are pre-processed and segmented, followed by feature extraction. The features are fed into a boosted decision tree classifier to estimate the probability of PDA or CHDs. Several mechanisms to combine information from different auscultation points, as well as consecutive sound cycles, are presented. The system is evaluated on a large clinical dataset of heart sounds from 265 term and late-preterm newborns recorded within the first six days of life. The developed system reaches an area under the curve (AUC) of 78% at detecting CHD and 77% at detecting PDA. The obtained results for PDA detection compare favourably with the level of accuracy achieved by an experienced neonatologist when assessed on the same cohort. Congenital Heart Defects (CHD) is malformations that occur due to abnormal development of the heart. These malformations can lead to a broad spectrum of clinical presentation, which implies a low or deficient performance of such a vital organ. Those diseases affect approximately 1% of newborns and account for 3% of all death among infants. Therefore, CHD is one of the most frequent causes of infant mortality . AccordiAuscultation is a part of the clinical routine examination in newborns. However, heart sound evaluation directly after birth can be challenging due to physiological shunt sounds through the Ductus Arteriosus. In the heart of the foetus, the role of Ductus Arteriosus is to allow the blood ejected by the right ventricle to bypass the lungs—a so-called right-to-left shunt. During the postnatal transition, the lung function changes starting with the first breath resulting in a shunt direction change during the normal transition to left-to-right. In the first 48 to 72 postnatal hours, Ductus Arteriosus closes in the vast majority of term infants . HoweverAn early objective screening method based on heart sound assessment should differentiate between sounds with and without signatures of PDA and CHDs. This is of great importance, especially within the first three postnatal days, in particular, to reduce unnecessary examinations and optimally use limited echocardiography capacities without missing PDA dependent CHDs. While the auscultation is a low cost and reliable tool to screen for neonatal heart defects, heart sounds interpretation is subjective, dependent on the assessor’s hearing acuity and the acquired level of expertise. Assistance from artificial intelligence (AI) can fill the gap and provide an objective interpretation of heart sound, to complement the traditional auscultation method .Thanks to the growing availability of data and computational power in recent years, AI and Machine Learning (ML) in particular, are becoming increasingly popular to solve many clinical healthcare problems, at times outperforming human decision-making ,16. ML cA digital stethoscope can record heart sounds to lead phonocardiogram (PCG) recordings. Most works on automated PCG classification have been performed in the adult population where the data are easier to be acquired, with a few publicly available datasets . SeveralConsiderably fewer works address automated PCG classification in the paediatric population. An ML can accurately diagnose PCGs compared in the 3-class classification problem  on a cohort of 106 children with an average age of 8 years old has been demonstrated in . The freEven fewer works have addressed the problem of automated interpretation of PCG in newborns. A statistical analysis of various features was performed towards automated detection of PDA murmur in a small cohort of 25 preterm infants . DiffereTaking into account that ultrasound screening has limited availability in both antenatal and postnatal screening procedures and that clinical examination by auscultation lies on subjective interpretation, this study aims to provide an objective decision support by discriminating the sound clips with and without signatures of PDA and CHD by means of ML. The proposed solution aims to improve early diagnosis of PDA or CHD, which will improve the efficiency of prioritisation of candidates for ultrasound assessment and improve the outcomes for treatment. The ML-based solution is designed to address two clinical problems, CHD vs. healthy, and PDA vs. healthy.The solutions are validated on a comprehensive real clinical dataset composed of heart sound recordings from a total of 265 newborns.The importance of various features and auscultation points is assessed for the task.The designed ML-based method to identify the presence of PDA signature in a sound clip is contrasted against the ability of an experienced neonatologist to do the same.The specific contributions of this study are: The deployment of the heart abnormality detection system developed in this study as a cloud-based objective decision support system is shown in The block diagram, with various stages of the classification algorithm, is shown in The dataset used in this study was collected between September 2013 and September 2018 at two hospitals in Ukraine: Kharkiv City Perinatal Center (Centre 1) and Maternity Hospital Nº1 of Kryvyi Rih (Centre 2). Informed parental consent was obtained for every participant before study inclusion. The study was approved by local ethics committees .In total, 265 newborns were included in the study, with the gestational ages ranging between 35 and 42 weeks. All patients had their diagnosis  confirmed by echocardiography. All patients were clinically healthy newborns at the time of the auscultation recording with no vivid signs of the CHD or pulmonary hypertension. In most cases, the diastolic murmurs developed later as the disease progressed and pulmonary hypertension developed, at that point the CHD can be suspected with other routine methods. The samples used in this study have no clinically detected diastolic murmurs, which would be of clinical significance for the early screening. However, 15 patients had systolic murmurs classified as physiological or innocent, according to echocardiography results. Consequently, those patients were categorised into the healthy group. Out of 265 patients in the database, there were nine patients with both PDA and CHD confirmed by the ultrasound, but for simplicity, this study categorises each patient within a single diagnosis group, either CHD, PDA, or healthy. Patients with both CHD and PDA were assigned into the CHD group due to a higher priority of such diagnosis. For each patient, PCG recordings were taken within the first six days of life from the five auscultation points shown in The normal heart sound consists of a cyclic sequence of two beats known as S1 and S2, producing the familiar “lub-dub” rhythmic sound that can be heard using a stethoscope applied to the patient chest. This sequence is driven by the cardiac cycle, which consists of alternating periods of heart contraction (systole) and relaxation (diastole). S1 is produced principally by vibrations created by the closure of the atrioventricular valves  located between the upper (atria) and lower (ventricles) chambers of the heart, at the beginning of ventricular systole. S2 is produced by vibrations created by the closure of the semilunar valves (aortic and pulmonary) in the arteries leading out of the ventricles at the end of the systole and beginning of the ventricular diastole. There is a relation between the PCG signal and the electrocardiogram signal (ECG). R-peak of ECG waveform matches the beginning of S1 sound in PCG and T-wave of ECG matches with the end of S2 sound . An examOther audible sounds that can be found during auscultation are murmurs. Those sounds are produced as a result of the turbulent flow of blood strong enough to produce audible noise. Heart murmurs are often signatures of heart valves’ pathological changes, and they are usually found during auscultation in primary healthcare. However, some murmurs are functional (innocent) in neonates and children, not any CHD. Murmurs can occur during systole or diastole intervals or continuously throughout the entire cardiac cycle.Since five auscultation locations are used in this study  each location emphasises certain heart sound characteristics. The mitral area is the best place to listen to S1 and also the murmur of the mitral insufficiency (regurgitation), or mitral stenosis. The aortic area is suitable to listen to S2, as well as the murmur of aortic stenosis. The pulmonic area is suitable to detect the continuous murmur of PDA, as well as murmurs related to pulmonary stenosis and pulmonary insufficiency (regurgitation). The tricuspid area and the left sternal border are used to detect the murmurs of tricuspid stenosis and insufficiency (regurgitation), as well as the murmur of the ventricular septal defect .In this study, the segmentation process has been performed manually: once the PCG recordings were made, those were manually segmented to heartbeat cycles and likewise each cycle into the four parts shown in Different types of features are extracted from each of the four heart-sound intervals due to the difference in the amplitudes and structure of the PCG waveform in each interval, as reported in . A totalBoosting is a method of building an accurate classifier from the ensemble of “weak” learning algorithms . Gradienh to the residuals, At each stage of gradient boosting, N is the number of training examples, K is the number of iterations, Here, Each function, t; and j, is obtained as follows:The objective function is optimised using the second-order Taylor expansion and is defined as follows:Each decision tree, Here, η and leaves space for other trees to improve the model. XGBoost implements the following regularisation techniques: rows (training examples) and columns (features) subsampling, which introduce randomness to the learning process; and shrinkage (learning rate), which scales new weights by a factor The models were constructed using the following settings: objective = binary: logistic, eval_metric = auc, eta = 0.03 (learning rate). max_depth: the number of branch levels for each decision tree;subsample: a ratio of randomly selected data rows or samples;colsample_bytree: a ratio of randomly selected data columns or features;tree_num: the number of decision trees used by the model.Other hyperparameters that control the complexity and regularisation of the model need to be tuned. These parameters are: From the trained model, a list of the most important features can be constructed. Since the large feature set is utilised in this work, one of the targets of the study was to select a smaller number of relevant features and maintain the same performance.The usage of an ML algorithm requires a clearly defined and independent model selection routine . The modmax_depth, subsample, colsample_bytree, tree_num. First, the three hyperparameters, max_depth, subsample, and colsample_bytree, are selected in a 5-times 2-fold CV  using out-of-fold data for assessment. After that, with those three hyperparameters now fixed to their optimal values, 10-fold CV is performed in order to generate an ensemble of 10 models optimised to the best number of boosting rounds (or the number of trees) by maximising the evaluation metric on the validation data set (early stopping).The model is optimised with respect to the following hyperparameters: The chosen metric to assess the performance of this study is the area under the curve (AUC) . This meFor each patient, the physiological information comes for each cycle for each auscultation point. Each patient can be represented as a sequence of feature vectors. The ground truth is available for each patient but not for each feature vector. The information combinations at feature and decision levels are experimented to check the model accuracy for the chosen aggregation methodology.At the feature level, the aim is to condense the information from all cycles into a single feature vector before the model. Two approaches are explored based on how the information given by the auscultation points is used. In the first approach, all cycle information is averaged separately per each auscultation point, condensing the patient’s information into just five feature vectors (one per each auscultation point). These five feature vectors are then concatenated into a single feature vector per patient. This first approach assumes that, if present, the audible signatures manifest in each cycle, but some auscultation points can be more important than others. In the second approach, the feature vectors are averaged across all the cycles and all the auscultation points. This approach considers that all patient’s cycles contain similar information, even across different auscultation points. When considering aggregation over multiple sources of information at the decision level (post-processing), the cycle-level predictions can be processed across each auscultation point first and then aggregated across patient using mean or maxima. All four possible cases are considered to determine if the decision needs to be done based on the common behaviour of features (mean) or on the oddities (max). The baseline performance is obtained by aggregating all predictions from all cycles and all auscultation points with mean with no feature transformation.The experiments mentioned above were performed first for the task of PDA vs. healthy. This means that only the data from patients belonging to healthy and PDA groups was utilised to generate the binary classification mode, excluding CHD data instances. Once the best methodology is defined, it is also replicated for the task of CHD vs. healthy .The feature importance is studied from the final model by quantifying each feature contribution to the classification task. The feature selection experiments are conducted to examine the performance with all features available vs. using just the Top-60, Top-30, Top-15, Top-10, and Top-5 features.Finally, it is desired to know how well the ML model performs in comparison with a trained doctor performing the same task with access to audio-only. The human performance is tested as follows: the doctor was asked to determine whether a patient is healthy or has audible signatures of PDA while listening to the audio data acquired from the five auscultation points. To make this process user-friendly, a graphical user interface (GUI) was designed in Matlab, as shown in To gain a more clinical insight into the model performance, A number of attempts have been made to differentiate normal and abnormal heart sounds in an adult ,34 and pWhen assessing the model’s performance, it is important to report the true generalisation error rather than the best achievable score. For the PDA/CHD detection systems to be useful in practice, their performance must hold on the unseen data. Moreover, the unseen data are expected to come from an unseen patient. When the validation loop is not conducted in a patient-independent manner (Setting 2), the models can be over-optimised, resulting in an overoptimistic assessment of the validation performance. The validation performance drives the selection of the model—which features to use, the hyperparameters of the model, pre-processing and post-processing routines. If it is not representative of the test performance, wrong choices can be made during the model development process. It can be seen from The accuracy of patient-dependent performance assessment (Setting 3) is much higher. This shows the unrealistically good score, which will not be achieved in practice on unseen patients. In practice, the algorithm is expected to perform on unseen patients ,23,24,34Each patient’s physiological data in this study can be represented as a set of multiple information sources. Each recording consists of audio data from five auscultation points. Each auscultation point consists of multiple heart cycles, and each cycle can be further segmented to four different stages . A single recommendation has to be made for a patient who requires an algorithmic approach to aggregate over multiple information sources. Each feature was averaged across multiple cycles  to ensurWhen comparing various ways to combine the available information sources at the level of features, shown in When considering aggregation over multiple sources of information at the decision level through the post-processing, the methods based on the presence of oddities (taking max probability) either across cycles or across the auscultation points or both did not boost the performance. This study intentionally utilises a large set of features from time and frequency domains to assess the level of their relevance for the considered tasks. Many of these features have been previously used for heart sound assessment ,35; otheThe extracted features describe the data within four different segments of a cardiac cycle. It can be seen from Most of the reviewed literature evaluates the detectors of murmurs ,24. In cIt is interesting to observe the performance of PDA detection improves with the age of the patient. PDA can be intermittent during the first days of life  and the Comparing results obtained with different machine learning algorithms on different datasets in different setups is a challenging task. A point of reference for a given dataset and algorithmic solution can be established by comparing with the human accuracy obtained on the same dataset. In , the comObtaining high-quality PCG from a newborn was difficult due to the child’s movements and discomfort. When possible, the recordings were made during the child’s sleep, sometimes through one layer of clothing. Thus, only 12% of the recordings examined by the health care professional were subjectively categorised as Good quality recordings. The rest were categorised as Bad (40%) or OK (48%). Approximately half of the data examined contained noises external to the heart sounds, making the task of discriminating PDA from healthy recordings more challenging for both ML and the healthcare professional on this particular dataset. Interestingly, no consistent dependency was observed between the quality of the recording and performance of either ML models or the human listener. This study utilised a manually segmented dataset. An automatic segmentation algorithm that does not require human intervention is preferable to automatise the segmentation process. There are no existing segmentation algorithms developed for the neonatal population. The algorithms that are created for the adult population  could poThe features considered in this work are relatively simple and computationally inexpensive. The extraction of advanced features from frequency or information theory domains can also be explored. There have been few attempts to use deep learning to combine feature engineering and classification in one end-to-end optimisation for processing of adult PCG . While sThe screening task considered was to determine whether the patient is healthy or recommended for additional inspection (either PDA or CHD). Therefore, determining the exact diagnosis, the type of the CHD, or the quantity of the CHDs and their combinations was not addressed in this study. The procedure of dividing PDA, CHD, and healthy in two separate tasks, PDA/healthy and CHD/healthy, is a simplification as in real life PDA and CHD could co-occur in the same patient. While the study focuses on auscultation alone, a total clinical assessment is a multidimensional process. Clinical examination, including auscultation, and pulse oximetry (PO) are used for screening for CHD. PO estimates the blood oxygen saturation using differences in light absorption characteristics of oxygenated and deoxygenated haemoglobin . If perfIn a subgroup of CHDs, the so-called ductus-dependent heart defects, the PDA needs to remain open. These defects might manifest clinically only during the functional closure of the ductus arteriosus, which may occur after the child is discharged home. The detected arterial duct before discharge can be a reason to refer the newborn for echocardiography . The intThis work presents the development of an objective clinical decision support tool based on machine learning (ML) to facilitate differentiation of sounds with signatures of PDA/CHDs, in clinical settings. The solutions are validated on a comprehensive real clinical dataset composed of heart sound recordings from a total of 265 newborns. To the best of our knowledge, it is the first study where the ability of the designed ML-based method to identify the presence of PDA signature in a sound clip is contrasted against both the ability of an experienced neo-natologist to do the same as well as against the ultrasound gold standard labels. This study has the potential of an earlier and more reliable screening to efficiently use the available resources without putting infants at risk of missed diagnoses and delayed treatment. www.hearttone.org.The future work will focus on assessing the difference between human performance and ML performance on the classification of various murmurs. The importance of pulse oximetry in improved detection of PDA and CHD suggests that integrating PO data in our framework will result in a more comprehensive assessment of the performance of artificial intelligence-augmented decision-making. The deployment of the models in real-life via cloud-based decision support will enable more data to analyse, more participation from medical professionals leading to a more accurate analysis. The developed models for PDA and CHD detection are in the process of being deployed in the cloud-based service


Although recently developed trackers have shown excellent performance even when tracking fast moving and shape changing objects with variable scale and orientation, the trackers for the electro-optical targeting systems (EOTS) still suffer from abrupt scene changes due to frequent and fast camera motions by pan-tilt motor control or dynamic distortions in field environments. Conventional context aware (CA) and deep learning based trackers have been studied to tackle these problems, but they have the drawbacks of not fully overcoming the problems and dealing with their computational burden. In this paper, a global motion aware method is proposed to address the fast camera motion issue. The proposed method consists of two modules: (i) a motion detection module, which is based on the change in image entropy value, and (ii) a background tracking module, used to track a set of features in consecutive images to find correspondences between them and estimate global camera movement. A series of experiments is conducted on thermal infrared images, and the results show that the proposed method can significantly improve the robustness of all trackers with a minimal computational overhead. We show that the proposed method can be easily integrated into any visual tracking framework and can be applied to improve the performance of EOTS applications. Visual tracking is one of the core problems in computer vision. The main task of short term visual tracking is to localize the target in consecutive frames in a video. Recently, visual tracking received much attention from researchers, resulting in significant improvements of the tracking algorithms. These improvements are reflected in the large number of tracking benchmarks ,4,5,6,7.Thermal infrared images have outstanding advantages over the standard RGB based imaging systems, i.e., the lack of light and reflections is not very problematic in TIR, while on the other hand, there is less color information, which can be useful for robust tracking. These properties result in TIR images having great application potential, especially in surveillance and object tracking missions. A typical tracking scenario in TIR is the tracking of an object that is far; therefore, it is small in the image. Another property is that TIR cameras are static most of the time, but when they are used to search and track to observe a target continuously at a long range at high magnification, the scene moves fast and suddenly, which causes significant camera movement and blurred images. The TIR sensor has a relatively small amount of photon energy compared to the RGB sensor; therefore, its integration time to accumulate photon energy and to make clear images is longer than the integration time of the RGB sensor in the readout integrated circuit (ROIC). TIR images are therefore easily blurred in the event of severe camera movements due to the longer integration time compared to general imaging sensors. As a result of that, trackers on TIR images often fail due to the image blur caused by fast camera motion. Most of the existing trackers do not explicitly address fast camera motion, and they use a fixed sized search region. As shown in The main contribution of the paper is a new method for global camera motion estimation that can be incorporated into most of the existing tracking algorithms. Correlation filter trackers achieved state-of-the-art results in the visual tracking tasks in recent years. In the following, we review some popular tracking methods based on correlation filters and describe how the field developed in the last few years. The discriminative correlation filter (DCF) methodology was introduced by Hester and Casasent . It was According to the development of deep learning methods, in order to improve tracking accuracy and robustness under the conditions of dynamic objects or camera motions, Danelljan et al.  proposedThe following authors made advancements in the size of the search region in correlation filters. Danelljan et al.  proposedThe EOTS applications with thermal imaging sensors mounted on aircraft, drones, or battle tanks are used under the conditions of static background images because of the long surveillance distance. However, they must perform observation missions under conditions of the complex movement of targets, as well as fast camera motions. Although their background is simpler than general near-field cameras, many of the conventional trackers fail to track the target robustly because the images are significantly blurred. We are motivated to detect this blurring phenomenon using the entropy value and to find the camera fast motion vector effectively to improve the performance of trackers. In this work, we propose a global camera motion estimation framework consisting of the gradient of the entropy sensor  of the thermal image sensor includes a process of setting the integration time for accumulating photon energy due to the low energy level of TIR detectors. Because of the integration time, image blur occurs when fast motion occurs in the camera. In general, the image blur of a thermal image can be detected by the low values of the entropy . We usedA as a finite set of I, the probability The entropy of information theory was proposed by Claude Elwood Shannon in 1948, which was used as a metric for information chaos . It has improved ,40. To oL, e.g., in the case of an eight bit grayscale image n is the total number of pixels in the image I. The image entropy The t and The current and previous time steps are denoted as mization . Shuigenmization . Considet, and The main influential sensitivities of the motion blur are the integration time and the frame rate. The integration time improves the quality of the thermal image and generates blurring ,43. GES framework estimates the translation of the global camera motion from two consecutive frames  trigger  detects f is defined as:x and y image coordinates. The derivation can be further expanded into the following form: Feature detection: In the first step of the BT process, the features on the two consecutive frames are detected. The cross-correlation method can be used as a conventional approach to detect the feature of two consecutive image frames and tracking the background. However, when the cross-correlation method is used to detect the background motion of the blurred screen, the convolution calculation of the image has to be performed several times over the entire range, which is very slow. The proposed tracker is required to be fast to be applied to the DCF based trackers of the EOTS in real time. Hence, we employed and modified a feature detector with fast speed and accurate feature point detection performance on the blurry images. Dan et al. performed experiments of four feature detection methods, Shi–Tomasi, Harris–Stephens–Plessey, SUSAN, and FAST . As a refined as:SSD feature matching : Global d by repeatedly calculating a point at which a relation between the detected feature points in frame t and frame The KLT method was used to estimate the final camera motion value In this section, we present the experimental results of the proposed method for the estimation of global camera motion. We extend four existing DCF based trackers, described in In the experimental comparison, we modified the four existing trackers, described in the following, with the proposed GESBT method. (i) MOSSE_CA  is a visThe VOT2019 RGB-TIR dataset  was used in all of the experiments consisting of 60 tracking sequences. Since they had several camera motion events, the dataset was used to demonstrate the performance boost of the proposed method. The standard VOT short term reset based methodology  was usedThe accuracy and robustness of the baseline and modified trackers are shown on the ARgraph in The VOT2019 RGB-TIR dataset had per-frame annotations of the visual attributes, and one of them was camera motion. We compared the trackers under this attribute only and show the results on the AR plot in Additionally, the PTB-TIR and RGB-T234 object tracking benchmarks had various thermal infrared sequences ,10. SpecSpeed analysis: The recently published CA method claimed that the speed was two to six times faster than the compared target-adaptive counterpart (AT) method, and it was shown that it could be applied as half speed 50%) compared to its baseline [0% comparIn this section, we compare the performance of the proposed method with conventional trackers when applied to an EOTS product, which was mounted on an aircraft where actual fast and complex camera motion occurred. There were two main reasons for fast camera motions in aircraft EOTS. First, when the flights or vehicles’ dynamic disturbance exceeded the camera stabilization performance, fast camera motion occurred. In fact, in the case of drastic flying of the aircraft or disturbance of vehicles when they were traveling on uneven roads, the limitation of the tracking performance occurred, and it was recorded in the user operating instructions. Second, the fast camera motion occurred when the camera motor was controlled by the joystick command. The operator tended to keep the target approximately in the center of the image; therefore, significant camera motion could happen when the camera position was adjusted. Such events often resulted in a tracking failure.We used the experimental environment as shown in As shown in In this study, we proposed a global motion aware method that can be applied to improve the performance of all visual object tracking algorithms for real-time applications. The method consisted of the camera motion detection module based on the gradient of the entropy sensor and the background detection module based on the feature tracking method. Global camera motion was estimated and used in the target localization step. Compared with the existing CA method, the robustness of the proposed method was increased especially when camera motion occurred. The additional computational complexity was very low. We expect that this method will motivate researchers to study the limitations of the trackers in thermal IR based electro-optical systems that are operated in real field environments. Future work includes incorporation of deep CNN features used for estimation of the global motion and formulating the problem as an end-to-end training task.