E × B drift that only effects the electrons. Wave-induced transport and loss have been one of many important issues in plasma physics over the past several decades. Conversely, the presently observed electron inward transport has a beneficial effect on the detachment by reducing the divergence of the expanding plasma beam; this finding will open a new perspective for the role of waves and instabilities in plasmas.Plasma flows in divergent magnetic fields resembling a magnetic nozzle can be found over wide scales ranging from astrophysical objects to terrestrial plasma devices. Plasma detachment from a magnetic nozzle is a frequent occurrence in natural plasmas, e.g., plasma ejection from the Sun and release from the Sun’s magnetic field, forming the solar wind. Plasma detachment has also been a challenging problem relating to space propulsion devices utilizing a magnetic nozzle, especially the detachment of the magnetized electrons having a gyro-radius smaller than the system’s scale is required to maintain zero net current exhausted from the system. Here we experimentally demonstrate that a cross-field transport of the electrons toward the main nozzle axis, which contributes to neutralizing the ions detached from the nozzle, is induced by the spontaneously excited magnetosonic wave having the frequency considerably higher than the ion cyclotron frequency and close to the lower hybrid frequency, driving an  During expansion, the plasmas can gain or lose energy and momentum via various static and dynamic phenomena, e.g., waves, turbulence, and electromagnetic forces. Processes in the MN play a significant role in the development of new-type space propulsion devices consisting of the high density plasma source and the MN, where ions are accelerated mainly into the axial direction by spontaneous steady-state electric fields and a Lorentz force due to the internal electron current and the applied magnetic field directs their momentum towards the axial direction13. Since most of the input electric power in the laboratory experiments is typically coupled to the electrons, their cooling and transport in the MN are essential to an in-depth understanding of energy transport and conversion processes18.Plasma flows in diverging magnetic fields, sometimes called a magnetic nozzle (MN), have been discovered to exist over wide scales ranging from astrophysical phenomena23. The ions are often unmagnetized in the MN, with trajectories dominated by the steady-state electric fields and deviating considerably from the magnetic field lines9, while the electron Larmor radius is much smaller than the plasma scale; hence they are still tied to the magnetic field lines. For the plasma to detach from the MN, both the ions and electrons have to be deviated from the field lines to maintain zero net current exhausted from the system. Otherwise, self-induced electric fields pulling back the ions will develop. One experiment on the plasma in the MN has discussed the anomalous transport of the electrons due to wave generation, where the wave was considered to induce an “outward” radial electron transport, resulting in the plasma loss from the MN and degrading the thruster performance24. Plasma detachment is also an important problem relevant to solar physics, i.e., the characterization of the boundary between the Sun’s magnetized atmosphere and interstellar space, where turbulent signals have recently been measured25. The detached plasmas escape from being governed by the solar magnetic fields to form the solar wind ejected toward surrounding planets including the Earth. In the magnetosphere, a whistler wave and a magnetosonic wave  can heat the electrons to high energies28 and also affect the plasma transport via pitch angle scattering and cross-field transport of charged particles30. Plasma transport and loss due to waves, instabilities, and turbulence have been one of the greatest problems for plasma confinement in thermonuclear fusion reactors31.Eventually, the plasma has to become detached from the magnetic field lines to generate the thrust by the electric propulsion device; otherwise, the charged particles would return to the thruster along the closed magnetic field lines. A few scenarios of the detachment have been proposed, e.g., magnetohydrodynamic and unmagnetization detachmentFor the present experiment, the cross-field “inward” electron transport induced by the spontaneously generated wave in the MN is demonstrated by considering a nonlinear interaction between the density and velocity fluctuations. The measured dispersion relation well fits that of the magnetosonic wave. Since the major component of the electric field for the wave mode is parallel to the wavenumber in the detected frequency range, being much higher than the ion cyclotron frequency and close to the lower hybrid frequency, it behaves as an electrostatic mode and the electric field fluctuation drives the cross-field transport only for the electrons. Simultaneously, the spatial ion velocity mapping shows the ions directed preferentially toward the main axis, compared to the divergent magnetic field lines, which is driven by the electrostatic acceleration due to the steady-state electric field. Therefore, it can be deduced that the wave-driven, cross-field, inward electron transport plays a significant role in maintaining the current balance between the electrons and the ions detached from the magnetic field lines.z axis are shown in Fig. x position. The rf power is presently set at 1.5 kW and turned on for 0.5 s, with the capacitors in the matching circuit tuned in advance to minimize rf power reflection (indeed no measurable power reflection was detected).The experiment is performed using a magnetized radiofrequency (rf) plasma source immersed in a 1-m-diameter and 2-m-long vacuum chamber evacuated by a combination of three turbomolecular pumps to a base pressure of less than y direction  aligned in the z) and horizontal (x) ion Mach numbers37, which corresponds to the averaged ion velocity. By taking the 38. The mean free path for the ion-neutral charge exchange collisions is about 50 cm and effectively acts as a drag force for the accelerated ions, resulting in the Mach number lower than unity in the averaged velocity measurement by the MP. However, the considerable deviation of the averaged ion velocity from the magnetic field lines can be confirmed here since the divergence angles of the ion velocity vectors are smaller than those of the magnetic field lines. Since the typical ion Larmor radius in the MN is larger than the radial scale of the plasma, the ion orbits are affected by the steady-state electric field rather than the magnetic field. The cross-field ion flux deviation from the MN in the r–z (or x–z) plane appears clearly on Fig. The Mach probe (MP) mounted on a rotational stage see Fig. a is usedmentclass2pt{minimmentclass2pt{minimmentclass2pt{minimz–x plane). It can be described using either the temporally varying or the frequency(f)-decomposed forms39:x direction. The direction of the cross-field electron flux can also be identified by the phase of E × B drift, the phase between x direction. 40.Insight into the transport of electrons in the diverging nozzle region can be obtained by determining the cross-field continuous electron flux E × B drift velocity  of the density (entclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaentclass1pt{minimaf) and corresponds to the wavenumber y direction; the PSD is simultaneously calculated from the f) obtained from the data taken at  =  and  are shown by colored scaling in Fig. S, D, P) elements of the dielectric tensor following Stix’s notation41:x, z) =  and the theory is performed using the measured local plasma density of k diagram dispersion relation43. In fact, the dispersion relation assuming cold plasmas has been well described and fitted to observations of the low-frequency waves, e.g., in Ref.44. The white solid lines in Fig. f) measurements. Therefore, the fluctuation at around 40 kHz can be considered to be the magnetosonic wave propagating in the azimuthal direction, where the wave spectra become discrete so as to satisfy both the dispersion relation and the azimuthal continuity of the electric fields.The cross spectrum of the measured x profile of x regions, respectively. The phase data at the frequency range of x direction. Since both x direction as already described, the result in Fig. Figure The cross-field electron flux in Fig. z axis, respectively. Conversely, the wave-induced electron flux x profiles of the fluxes z axis, respectively. Both the ion and electron fluxes show less divergent transport than the magnetic field lines, the former induced by the steady-state electric fields near the source exit and the latter by the cross-field inward transport due to the magnetosonic wave. It can be seen that the electron flux is close to a few tens of percent of the ion flux in the peripheral region, indicating that the wave-driven inward transport process for electrons makes a contribution to the current balance with the ions detached from the magnetic fields.The ion flux mentclass2pt{minimmentclass2pt{minimmentclass2pt{minimr–z plane9. The ions deviating from the field lines seen in Fig. 45, whereby zero net current is maintained along the field lines.As observed previously, the unmagnetized ions accelerated by the steady-state electric fields having both the axial and radial components do not perfectly follow the magnetic field lines; the electrostatic ion acceleration induces both the ion fluxes parallel and perpendicular to the magnetic field lines in the E × B induced instability such as a Simon–Hoh type is stable for this case46. Therefore, the energy source of the wave is neither the pressure gradient nor the potential gradient. Previous studies have shown that the magnetosonic wave in a frequency range of 47, where the likely energy source of the wave is the ion energy across the magnetic field lines. Our measurement on the ion velocity mapping (Fig. r–z plane, where the cross-field ion flux is maximized at the peripheral region. Therefore, it can be deduced that the energy of the ions deviating from the magnetic field lines is the energy source of the magnetosonic wave. The wave-induced inward electron flux attempts to neutralize and mitigate the ions deviated from the field lines, where the deviation of the unmagnetized ions is due to the presence of the steady-state axial and radial electric fields as observed in a number of experiments, e.g., Ref.9. Based on these considerations, it is considered that the magnetosonic wave and electron inward transport could occur in various types of plasma flows in a MN where the unmagnetized ions deviate from the field lines.To discuss the energy source driving the wave, the radial density profiles are plotted by crosses in Fig. mentclass2pt{minimThe ions in the MN are indeed unmagnetized here; the driving force for the ion acceleration and the ion flux deviating from the magnetic field lines is the steady-state electric fields. When a part of the ion energy is consumed to generate the wave, the ion energy would be damped. As the fluctuation much higher than In the plasma expanding in the MN, where the ions are accelerated by the steady-state electric field, are unmagnetized, and deviate from the field lines, fluctuations having a frequency less than the lower hybrid frequency and much larger than the ion cyclotron frequency are detected and identified as the magnetosonic wave propagating primarily in the azimuthal direction. In the detected frequency range, the dispersion branch of the magnetosonic wave is likely an electrostatic wave having the electric field fluctuation parallel to the wavenumber. It is demonstrated that the nonlinear interaction between the density fluctuation and the electric-field-driven velocity fluctuation related to the magnetosonic wave induces an inward cross-field electron transport toward the main axis of the MN. The electron cross-field transport plays a significant role in the current balance with the accelerated ions detached from the magnetic field lines, which could be a common phenomenon in terrestrial plasma devices and naturally occurring plasmas.Error analysis of the cross-field electron transportTo assess the possible error in the wave-driven cross-field electron flux, the signals of the ion saturation current


Introduction: Many medical students’ initial experience obtaining a history from a pediatric patient happens in their clerkship years. There is a shift in medical education to provide early clinical experiences to train physicians. To increase the exposure to pediatric history in the pre-clinical years, we developed this simulation-based session involving students in their second year of medical school. They are tasked with eliciting a history from a baby provided by a teenager who functions both as a standardized patient (SP) and the parent of the infant. Our goal was to have second-year medical students learn and practice interviewing an adolescent while obtaining history about an infant to assist in the transition to Year three Pediatric clerkship.Approach: Collaborating with the Office of Diversity at our medical school, we recruited students registered in medical academies in public middle and high schools in our county and asked them to be part of this simulation-based activity. A majority of these medical academy students are underrepresented in medicine (URiM). The students functioned as SPs for pre-clerkship medical students while gaining exposure to a career in medicine and the medical school environment. The medical students obtained a history, with faculty providing formative feedback, followed by documentation of the encounter.Outcomes: Medical students felt they gained skills to communicate with caregivers of pediatric patients. They also practiced the skill of eliciting a pediatric history from an infant whose parent is a teenager. The middle and high school students that functioned as SPs gained a better appreciation for the medical education system and felt that the experience was valuable for all parties involved.Discussion: This session exposed pre-clerkship medical students to the nuances of eliciting a pediatric history from pediatric caregivers while also engaging URiM from middle and high school in the medical education process. This session could be used at other institutions to expand diversity in the medical field while also providing pre-clerkship medical students with pediatric experiences. This article was previously presented as an oral presentation at the AAMC Group on Education Affairs (GEA) Virtual Regional Spring Meeting on April 21, 2021. Simulation is an active learning approach, and is used in pre-clerkship medical school curricula to teach clinical skills . In addiPediatrics is a specialized field in medicine, and learners with limited personal experience or exposure to children can find communication, interaction, assessment, and the provision of developmentally appropriate care difficult . The abiThis technical report describes a simulation-based teaching session created for pre-clerkship medical students in the first semester of the second year of medical school to learn how to elicit a pediatric history of a baby where the caregiver is an adolescent SP. These medical students learned how to elicit a complete medical history from an adult during their first year of medical school using adult SP. Eliciting the history from a historian, instead of the patient, is a skill that the pre-clerkship students also must learn. The purpose of our study is to: (1) have second-year medical students obtain a pediatric history, (2) obtain a history from a secondary source, in this case, a parent, and (3) provide exposure to middle and high school students to what happens in medical school.This article was previously presented as an Oral Presentation at the AAMC Group on Education Affairs (GEA) Virtual Regional Spring Meeting on April 21, 2021.This simulation session uses middle and high school students as SPs. Recruitment of middle and high school students was done in collaboration with the Office of Diversity at our medical school. This office implements the Community Engagement & Pathway Program at medical academies in middle and high schools in our county. Medical academies in these middle and high schools are designed to provide their students an opportunity to develop the skills needed to compete for, enter, and graduate from health professions schools once they finish high school. Pathway programs have demonstrated increased engagement of high school students from diverse backgrounds in the healthcare professions ,15. SimiWe created an SP scenario Table  to mimicPrior to organizing this learning activity, we submitted and received approval from our University’s Institutional Review Board. Parental consent and child assent were sought with training as per project protocol. As part of our planning process, the parent(s) of the middle or high school students received a copy of the SP scenario prior to the activity for them to review it and provide consent for their child to participate as an SP. We had two sets of parents who declined to consent due to concerns of sexual history. Once parental consent and child assent were obtained, the SPs received a copy of the scenario and initial training from their school teacher. On the day of the simulation, the students arrived at our institution for additional training. Female students played the role of the SPs in our activity, but the scenario could be converted to having a male parent as the historian. Each SP was asked to carry a baby mannequin wrapped in a blanket to mimic a real-world situation.We planned and completed the activity in two afternoons, with half of the class of second-year medical students attending each session. We reviewed the checklist Table  that wasInputs and processesIn order to complete this activity, we needed the following resources:Physical Space: Simulation center with eight standardized patient exam rooms, eight infant mannequins, lecture hallDocuments: Checklist of benchmarks, SP story, lecture PowerPoint reviewing the pediatric history checklist, “chart” documents for the students to review in advanceStaff and Faculty: Staff to recruit and train SPs, partnerships with community public schools, SPs from local middle and high schools, eight faculty to supervise each SP room, one faculty to present the lecture and debrief the session, staff member to run the activity and movements of students and facultyPre-briefingA 30-minute pre-brief session was organized on the day of the session before the interaction with the SP with an MS PowerPoint  presentation for the second-year medical students to learn the difference in eliciting a pediatric history and to review the questions in the checklist that the student will be using with the SPs in the exam room. During this time, medical students and faculty were made aware that SPs were adolescent minors with parental consent for the interview process but will not perform a physical exam on the mother or the baby in this simulated case. In addition, each medical student was provided with a “chart” document that has written instructions  could be asked to be the SPs.We began this study wanting to prepare a simulation-based activity with the goal of (1) having students obtain a pediatric history, (2) obtaining a history from a secondary source, in this case, a parent, and (3) providing exposure to middle and high school students to what happens in medical school. As demonstrated in our results, students found this session to be helpful to their understanding of pediatric history and felt that the experience was relevant to their medical education. They also felt the format and use of middle and high school students helped meet the learning objectives. The SPs also felt that the session was worthwhile. However, there were some limitations to the session:(1) Parental consent. A larger group of middle and high school students must be available to account for the situation when parents may not consent to the script;(2) As middle and high school students are not professional SPs, it requires a relatively simple story/scenario to which they can relate easily;(3) The physical exam was not performed in this activity to avoid issues with examining minors;(4) Coordination of the schedule of the middle and high school students to fit the schedule of the medical school students, as we only held the activity on two specific afternoons. The dates need to be reserved as early as possible during the planning process;(5) There are many resources necessary, including space and faculty time. Other institutions may have more exam rooms available and can accommodate more students per session and limit the activity to only one afternoon to streamline any scheduling conflict.This technical report submission is significant for two reasons. First, pre-clerkship medical students learned to elicit a pediatric history from a teenage SP who is the caregiver of her infant. Second, it utilized middle and high school students as caregiver SPs. These two concepts are gaps in the literature. More importantly, we achieved our main goal for pre-clerkship medical students to learn the differences when eliciting the medical history in pediatric patients, as compared to adults, before entering their clerkship years. This simulated activity was prepared for pre-clerkship medical students to elicit the medical history in 30 minutes. It can be adapted in a shorter amount of time in the case of more experienced students. The activity was scheduled over two afternoons for educational purposes but also can be a stand-alone formative or summative assessment or included as a station in an Objective Structured Clinical Exam (OSCE) format. The checklist was used consistently by faculty for formative assessment of the medical students. It could also be used to provide a summative assessment to students following the OSCE format.


R2 was 0.3). By examining the DS events reported in the SED based on meteorological observations including wind speed, visibility, and weather codes, we determined that the SED was not only missing many DS (visibility <1 km), but also included many blowing dust (BLDU) events. 49.9% of 491 reported DS events in SED had visibility >1 km and were incorrectly reported as DS. Underrepresentation of DS and inclusion of BLDU may be partially due to the diverse sources contributing to the SED and a lack of verification of the reports and their consistency. Although the SED is an extremely useful and valuable database of impactful weather, including DS, the issues found in this study warrant caution in use of this dataset for many geohealth applications.Windblown dust impacts human health, air quality, and climate. The National Weather Service Storm Events Database (SED) is a widely used dataset of significant or unusual weather, including dust storms (DS), and resulting deaths, injuries, and material losses in the USA. The SED is frequently used by medical, social, and atmospheric scientists. However, it is uncertain whether this dataset reliably represents spatial and temporal variations and trends of DS. Analyzing the SED from 2000 to 2020 identified 1,167 DS reports; removing reports of the same event from multiple locations left 647 DS in 21 USA states. The number of DS ranged from 12 in 2008 to 53 in 2018, with no strong interannual trends detected  eventsAlthough the Storm Database is representative and useful, it may not be comprehensive or complete and thus should be used carefullyThere is a need for a new database of dust events, that will include all levels of dust events (including blowing dust and DS) Dust paAccording to the World Meteorological Organization (WMO), a DS is defined when the horizontal visibility is reduced by dust in the air to less than 1 km UNEP, . The USA10 concentrations or the ratios between PM10, and PM2.5 concentrations measured by air quality monitoring sites  and the National Oceanic and Atmospheric Administration is the most widely used dataset of information on significant and/or unusual weather phenomena in the USA. This database is used to populate an official publication titled ta NCEI, . Accordita NCEI, .The SED has been widely used by researchers to examine extreme weather's impact on human health and safety. For example, in the atmospheric science literature, it was used to examine mortality rates due to heat and cold  losses. The SED data are gathered in several ways. One way is by using the NWS storm report logs. These reports are usually gathered during the event itself, but sometimes can be added a few days later. SED data come from many sources including agency/official personnel including law enforcement and government officials, emergency management officials, departments of highways, NWS damage surveys or employees, trained spotters, and official meteorological station reports, as well as from the public including broadcast media, newspapers, and social media NCEI, . There a−1), low visibility <1 km, and reports in the weather code  from an ASOS that was in close proximity to the location report in the SED.To examine each of the SED DS events, an in‐depth analysis was performed for the entire database (for each event reported). Examples of selected locations  will be presented. Identification of each DS event was based on meteorological information retrieved from the Meteorological Aerodrome Reports that provide 5‐min to hourly meteorological measurements  collected by the ASOS that were downloaded for each DS event (for each state) that was reported in the SED. Observations and identification of dust events/storms were based on the method used in Kelley and Ardon‐Dryer  which in33.1A total of 1167 DS reports were identified from the SED from 1 January 2000 to 31 December 2020. The greatest number of reports was for Arizona with a total of 480 DS reports while only one DS event was reported for the states of Delaware, Indiana, Missouri, and Wisconsin. In most cases, there was only a single report per day, but there were many with multiple reports of a single event (from multiple sources and locations). As an example, the highest number of reports for one DS event was on 24 February 2001, in Oklahoma which had a total of 29 different reports from various sources and different counties. This creates a potential oversampling issue that becomes problematic if this dataset is used to derive long‐term dust trends related to number of dust storms.To make sure an event was not reported multiple times, DS reports, for each state (combining reports from multiple counties and sources per event), were combined to represent a single event per state (1 day). In some cases, two different DS were reported with several hours gap between them. In these cases, the DS was counted as two separate events. The start and end times of each event per state were recorded and combined per event.R2 was 0.3) but an increase in the overall number of DS reported was observed (slope was 1.0 per year). It is uncertain if this increase was a real increase in the number of dust storms over time or could have been caused by increases in population and weather awareness causing increased reporting  to 53 events (in 2018) Figure . No strot et al.  and summt et al. ), as thet et al.  with onet et al. . Most oft et al. , yet sin3.2A total of 21 states had reports of DS in the SED between 2000 and 2020 Figure . Some st3.3The SED is known to be one of the most commonly used data sources that examine hazard losses  was found between the total number of DS per year and the number of deaths, injuries, or material losses, but a positive slope was observed for all three . It should be noted that less than 7% of the DS events had reports of injuries, while less than 3% had reports of deaths. We also noticed that several DS events had in their episode narrative, which is part of the database, reports of injuries , or death  but no reports (counts) of injuries or death in the database. Some of the episode narratives also reported damages  but no monetary valuation was provided for the material losses for the event.Since the SED provided information on DS events that were associated with deaths, injuries, and material losses (properties and crops), an examination of the reported number of deaths and injuries (direct and indirect), as well as property and crop losses, was performed Table . The hig3.4An examination of the reporting source of the DS events in the SED Figure  shows thSince this is the only known nationwide database for DS events in the USA it was impossible to compare or verify all the DS events. Therefore, we decided to explore each of the 647 DS reported. First, we identified the location of the events in the SED based on the county and the episode narratives which may provide detailed information . Next, we examined all the ASOS in the state with the DS report with a focus on the ASOS that was closest to the location reported. The meteorological conditions from the ASOS were examined to identify each dust event with wind speed and weather code (if available). Next, we examined the visibility values during the time reported, if the horizontal visibility was below 1 km the event would have been defined as a DS, if the visibility was >1 km it would not be defined as a DS but as BLDU.Out of the 647 DS reports in the SED, 156 could not be examined as there was no ASOS near the location reported or the ASOS was not operational at the time of the DS event, leaving 491 reported DS that could be examined. Out of the 491 DS reported in the SED, 187 events (38.1% of the 491) were confirmed as dust storms and had visibility below 1 km, and 59.9% of these 187 DS had visibility <0.4 km. In addition, we noticed that 10 of these DS in the SED were reported in one place (that did not have a reduction of visibility) but the DS was observed and identified in another location in the state during the same time. The remaining 304 DS reports contained 57 events that did not have any documented reduction of visibility (across the state) although strong winds were observed, and 245 (49.9% of the 491 DS reported in the SED) should have been defined as BLDU events, as the visibility was reduced but it was >1 km. We also noticed that one DS event reported in the SED was a dust devil. Almost all the states examined had BLDU events that were inaccurately listed in the SED as dust storms or other reported DS that could not be examined or meet the 1 km threshold to be defined properly as DS. By examining each of the DS, we noticed that one of the DS from New Mexico that had the longest duration reported (1 April to 9 April 2011) seems to have a mistake in its start date included in the SED.To highlight some of these findings several locations were examined to present issues with the accuracy of the SED reports. These locations include several locations in Utah, Denver, and La Junta in Colorado, Lubbock and El Paso in Texas, as well as the Greater Phoenix area in Arizona, see maps in Figure S2 in Supporting Information A similar analysis was performed for Colorado which had 15 DS events in the SED, but only seven of them could be examined with an ASOS near the reporting area. Two events were confirmed as DS and five were occurrences of BLDU with visibility that did not meet the DS criterion. Based on these findings we decided to examine two ASOS units in Colorado from 2000 to 2020  along with an underrepresentation of events that do fit the criteria needed for a DS but are not included in the SED. Peterson and Zobeck , who useWe suggest that these issues could be caused by multiple factors. There is potential confusion in the reporting protocols for DS events as the NWS  states tAn additional factor could be attributed to the wide range of sources used to report DS events Figure . Storm EStorm Data database for quantitative studies of dust storms (or other impactful weather phenomena) and their effects.The SED performs a valuable public service to many user and stakeholder communities in assembling data from across the USA on daily weather events of an impactful nature, and we appreciate the importance and utility of the database, as well as the difficulty in assembling it. We believe that because it is so widely used by professionals in diverse fields, accuracy should be the ultimate goal, therefore there should be greater emphasis on improving the methodological foundation of this database. There is a need for a more formal, efficient, precise and accurate way to collect the storm data, as well as to validate and verify the reports in the SED. Investigators in many different fields need to know that the data in the SED, while representative, may not be comprehensive: the data are useful, but not necessarily accurate, and thus caution is warranted in using There appears to be a lack of consistent definitions and reporting of “dust storm” and of dust weather in general in the USA, as well differing understanding of the meaning of the term “dust storm” by persons outside atmospheric science. What is more, consistent definitions of “dust storm” have not been used by those investigating the climatology of dust weather and the health, safety, and other societal effects of dust across the USA. This potentially limits the inter‐comparability of these and other studies to each other and to analyses of dust occurrence in other nations, and also limits understanding their associations with human health and safety and societal impacts. In addition, since the USA experiences far more events of BLDU (visibility >1 km) than it does dust storms, we note the need for a new database that will include dust events of all types including BLDU and dust storms.4Storm Data for health, safety, and other studies will use it with caution and understand its potential limitations which might affect the findings of their research.This study examines the long‐term variations of reported dust storms from the SED and its reliability and usefulness as well as limitations as a source for documenting the occurrence of dust storms across the USA. While this database provides a large amount of useful information for understanding the frequency, distribution, importance, and impacts of significant weather across the USA, including dust storms, our analysis of events occurring from 2000 to 2020 shows that it is lacking many dust storms that occurred during that period, and also contains many events of BLDU (with visibility >1 km) that should not have been reported as dust storms. There are also multiple entries in the database from various sources for a single DS that could be problematic if the number of entries in the dataset is used to derive long‐term dust trends. Some of the causes for the underrepresentation of DS events or confusion in reporting in the SED could be attributed to the diverse sources contributing to the reports, potential lack of consistency in reporting criteria, and lack of verification of the reports. Although it is one of the most widely used dust databases and impactful weather available for the entire USA, the issues found in this study raised questions on its, accuracy, and reliability as a dataset to study dust climatology and associated health and socioeconomic effects. Therefore, we recommend that those using the SED or The authors declare no conflicts of interest relevant to this study.Supporting Information S1Click here for additional data file.


Summary methods seek to infer a species tree from a set of gene trees. A desirable property of such methods is that of statistical consistency; that is, the probability of inferring the wrong species tree (the error probability) tends to 0 as the number of input gene trees becomes large. A popular paradigm is to infer a species tree that agrees with the maximum number of quartets from the input set of gene trees; this has been proved to be statistically consistent under several models of gene evolution. In this paper, we study the asymptotic behaviour of the error probability of such methods in this limit, and show that it decays exponentially. For a 4-taxon species tree, we derive a closed form for the asymptotic behaviour in terms of the probability that the gene evolution process produces the correct topology. We also derive bounds for the sample complexity (the number of gene trees required to infer the true species tree with a given probability), which outperform existing bounds. We then extend our results to bounds for the asymptotic behaviour of the error probability for any species tree, and compare these to the true error probability for some model species trees using simulations. A central problem of phylogenetics is the inference of the evolutionary history of a group of species in the form of a species tree, where leaves represent extant species and internal vertices represent speciation events. Likewise, the gene families contained within the genomes of the species have their own evolutionary histories, which can also be represented by trees that can be considered as evolving ‘within’ the species tree. This implies that the gene trees are heavily dependent on the species trees.Historically, species trees have been inferred using so-called ‘concatenation’ methods, where the sequences of individual genes are concatenated together to form a set of ‘species sequences’, which are then used as input to a tree-building method of choice, often maximum-likelihood based  under the multispecies coalescent  are well-established, dating back to Goodman  is statistically consistent. This becomes progressively more difficult as the models increase in complexity, but it has been proven that this is indeed the case for the DL model  as the number of input gene trees, N, becomes large. Rather surprisingly, while there has been considerable interest on whether the error probability goes to 0 or not , no-one (to the best of our knowledge) has studied the asymptotic behaviour of the error probability when it does go to 0. Our results below show that the decay is exponential in nature, which is unsurprising but does not seem to have been theoretically proven before.We approach this problem in a general way by not restricting our consideration to the MSC or any other particular model of gene evolution. Instead, we consider the asymptotic behaviour of the probability of inferring the wrong species tree (the sample complexity (the number of gene trees required to infer the true species tree with a given probability) of ASTRAL. They derived bounds for this quantity under the multispecies coalescent, and recently Hill et al.  for the error probability for any species tree. Using simulations, we compare our bounds with the true error probability for some sample topologies.In this paper, we study the asymptotic behaviour of the error probability as r et al.  in practS has 4 taxa. We suppose that N unrooted gene trees are simulated from the species tree under an unspecified gene evolutionary process that has probability S, and equal probability We first study the case where the species tree We begin by defining a function that we will use repeatedly throughout this paper.f(p) be the functionLet We illustrate the behaviour of this function in Fig. N, and derive a closed form for the exponential constant that only depends on the probability p of producing the correct topology.We now derive the central result of this paper: we show that the asymptotic behaviour of the error probability goes to 0 exponentially with Given a 4-taxon species tree, let N and Let The correct species tree will be inferred if c to maximise the (log-)probability of this event:cN is an integer for this value of c; however, as Using Stirling’s formula N , the claim is proved, as is the result. Hence Note. An initial attempt at deriving this result involved using a normal approximation to the multinomial; rather surprisingly (to us), this failed because the approximation of multinomial tail probabilities became inaccurate faster than the normal approximation became accurate.This theorem leads to an immediate result on the Robinson-Foulds (RF) accuracy of the inferred species tree.S and the tree inferred by ASTRAL behaves asUnder the conditions of Theorem This follows immediately from Theorem N, not just in the limiting case.Theorem Under the conditions of Theorem The proof uses a bounded version of Stirling’s formula and is given in Appendix A.Finally, we note that, depending on the gene evolution process, it is possible that the two incorrect topologies may not be generated with equal probability. This cannot happen for the MSC, but in models which include duplication it may occur for species trees that are not ultrametric, or if duplication rates are allowed to vary between branches. This can, and more easily, also happen in models including lateral gene transfers or introgression. In these cases, Theorem Given a 4-taxon species tree, let the probabilities of producing the three quartet topologies be We sketch a proof in Appendix B, and also state a generalisation of Theorem S with an arbitrary number n of taxa. As before, we start by assuming that for any quartet, the gene evolution process produces the two incorrect topologies with equal probability.We now consider the case of a species tree x of the species tree which divides the extant species into four clades positively correlated if the events of producing each of the three topologies are positively correlated between the two quartets; that is,To derive a lower bound on the asymptotic behaviour of the error probability, we require an assumption on the gene evolution process. Consider an internal branch S, assume the gene evolution process is positively correlated. Let S of producing the correct topology. For any internal species branch S into, and letGiven a species tree i has a majority of gene quartets with the correct topology. ThenTo derive the upper bound, a sufficient (but not necessary) condition to infer the correct species tree is that each of the mentclass2pt{minimx, and consider the species quartets that contain one species from each of the clades x to this wrong topology will result in a species tree that agrees with more of these quartets, and not change the agreement with any other quartets. This improves the quartet score, a contradiction.To derive the lower bound, consider an internal species branch Let N gene quartets, we have x which maximises the resulting bound, this produces the lower bound.Now although gene quartets from different gene families are independent, this is not the case for gene quartets from the same gene family. Since the gene evolution process is positively correlated, the probability of mentclass2pt{minimO(N), we can say that the error probability also has this limiting behaviour as Finally, because both the lower and upper bounds are n, the size of the species tree, whereas the lower bound does.Note in particular that the upper bound does not depend on any species tree. While the derivation of the upper bound is very similar to that in Shekhar et al. , the lowa, b, c, d) in  in  have exax will tend to maximise the lower bound. Since f(p) is a negative and decreasing function, it is maximised for small p. However, we also wish to simultaneously minimise x is a branch near the leaves, so that three of the four clades are small. The smallest possible value for this quantity is either x is the internal branch of a subtree , c)) or x is one of the internal branches of a subtree ,  )). Note that the first case in particular corresponds to the construction used to prove Claim 2.1 in Shekhar et al. , given by the relation f, but we have already used this notation for the asymptotic growth constant function.) Substituting this relation into Theorem The results in the previous sections apply under any model of gene evolution, requiring only the probability mentclass2pt{minimg(l) is the functionUnder the multispecies coalescent, the minimum number of genes required to correctly reconstruct a 4-taxon species tree with ASTRAL with probability at least The first expression follows immediately from setting mentclass2pt{minimc in l:f(p) and expanding as a Maclaurin series in l gives the asymptotic behaviour for g(l). A more detailed derivation is given in Appendix C. To derive the mentclass2pt{miniml below a threshold depending on l.Corresponding bounds for the sample complexity are given in Shekhar et al. . In the N under the MSC from Theorem p. In Fig. l; however theirs works better for small N and l. We can also see that the asymptotic behaviour lies between our bounds, which is expected in the asymptotic limit but appears to hold for all N anyway.We can derive bounds on the error probability for all N numerically . We show the results of this in Fig. N to reach the desired error probability, so the better asymptotic properties of our bounds result in tighter bounds than that of Shekhar et al.  and all other branches of length l.We follow the simulations of Shekhar et al.  and studThe branch that provides the best lower bound in Theorem N independent gene trees under the MSC model for a range of N from 10 to 60000. The gene trees are then input into ASTRAL to infer a species tree, which is then compared with the true species tree. This is done for a range of l from 0.005 to 0.1  of ASTRAL in the large-sample limit (as the number of input gene trees becomes large). In particular, we show that the error probability goes to 0 exponentially with respect to r et al. .N has a natural boundary which it cannot go beyond. On the other hand, the increasing amount of whole-genome data available does allow a greater and greater number of genes (and therefore gene trees) to be used in species tree inference, and so an exploration of the behaviour of these methods in the large-N limit is of practical importance. In particular, our results are good enough to be useful in the question of determining the sample complexity, which is of great practical interest as it allows one to estimate a priori how many gene trees need to be extracted from the genome for use in species tree inference.It is true that in practice each species only has a finite number of genes (where a gene is simply a non-recombining locus in a genome); thus n species, which additionally requires positive correlation) apply equally well to these models, and to future models that may additionally include other processes. We require only the ability to calculate the probability of the gene evolution process generating a correct quartet topology. While this is not always an easy task theoretically under the more complex models, it can often be estimated very accurately via simulations on 4-taxon species trees (vastly more efficient than conducting simulations over many species).Our results are quite general, in the sense that although they are expressed in relation to ASTRAL, they apply for any species tree inference method which solves the maximum quartet support species tree problem. Nor are they limited to the multispecies coalescent model; although this is the dominant model at the moment, this may change with the recent rise of unified models that also include DTL processes, such as DLCoal or MLMSC. Our results . However, it is not trivial to extend this argument to more complicated models such as DLCoal or MLMSC, and it remains an open question whether these models are indeed positively correlated or not.p of producing the correct quartet topology . For our results to hold, it only matters that Finally, we note that the important practical consideration of whether the gene trees are reconstructed with or without error does not affect our theoretical results in Sects. r et al. , this wiFor Sects.


Scientific Reportshttps://doi.org/10.1038/s41598-021-04359-5, published online 07 January 2022Correction to: The original version of this Article contained errors as the simulation software used for the submission  did not work as anticipated. As a consequence, the optical properties of the first skin layer were taken into account for all seven simulated skin layers. After fixing this bug, all simulations on which the paper is based were re-run. As a result, the Materials and Methods, Results, Discussion and Conclusion sections, tables 1 and 2, figures 2, 4 and 5 were updated.In the Materials and Methods section, under the subheading ‘MC simulation model and optical properties’,“The illumination was implemented as a fiber with core diameter now reads:“The illumination was implemented as a fiber with core diameter Knorm’,In the Materials and Methods section, under the subheading ‘SP-DRI and modulation parameter “Cross-sections through this two-dimensional data set are further filtered by a Savitzky–Golay filter . For an exemplary data set, this can be seen in Fig. now reads:“Cross-sections through this two-dimensional data set are further filtered by a Savitzky–Golay filter . For an exemplary data set, this can be seen in Fig. “As just mentioned, the SP-DRI modulation can be obtained from cross-sections through the two-dimensional data set .”now reads:“As just mentioned, the SP-DRI modulation can be obtained from cross-sections through the two-dimensional data set .”(x2| y2) [px] value was incorrect for “Light source”.In addition, Table 1 contained an error, where the The correct and incorrect value appears below.Incorrect:Correct:The Article also contained errors in Fig. In the Materials and Methods section, under the subheading ‘Random Forest approach and further analysis’, the following sentence was removed:“In case the outcome of the preceding step is not sufficient, the importance of the predictors could furthermore be examined with a neighborhood component analysis for regression. Also this algorithm is typically used to select features as part of data preprocessing. The predictor and response variables were identical to those used in the previous step. This was done in Matlab via fsrnca.”In addition, under the same subheading:“Based on the previous findings, only the most important predictor(s) was/were included in the further RF regression ensemble model. Twenty percent of the data was withheld as test data while the rest of the data was used for training. This procedure was repeated 20 times with the data being randomly assigned to the training and test set, the results were averaged afterwards.For this run, within fitrensemble the automated optimization of the RF hyperparameters was enabled to find hyperparameters that minimize the five-fold cross-validation loss. Thus, the algorithm sought the optimal values for the ensemble aggregation method (Bag or LSBoost), the number of ensemble learning cycles, the learning rate for shrinkage and the number of observations per leaf.”now reads:“Based on the previous findings, only the most important predictor(s) was/were included in the further RF regression ensemble model. To find hyperparameters that minimize the five-fold cross-validation loss, the automated optimization of the RF hyperparameters was enabled within fitrensemble. Thus, the algorithm sought the optimal values for the ensemble aggregation method (Bag or LSBoost), the number of ensemble learning cycles, the learning rate for shrinkage and the number of observations per leaf. The hyperparameters found in this way were later on used during training of the individual RF models .”“This analysis is performed using the test data that was also used in the previous steps. Thus, for each set of test data, six capillary diameters can be estimated based on the six now reads:“This analysis is performed on the basis of twenty percent of the data only (test data) while using the rest of the data for training the RF model. Thus, for each set of test data, six capillary diameters can be estimated based on the six In the Results section, under the subheading ‘“It was found that According to the results on the importance, It was possible to find an analytical expression for this relationship with a very high model fit  Graphical representation of data sets for now reads:“(b) Graphical representation of data sets for In the Results section, under the subheading ‘“It was found that According to the previous results, The quest for an analytical expression had to take place in the three-dimensional space. With a model fit of describes the relationship. Again, the influence of It was also investigated to what extent this analytical function fits the test data described above. This resulted in now reads:“It was found that Also in this case, the quest for an analytical expression had to take place in the three-dimensional space. With a model fit of describes the relationship. Again, the influence of both parameters is assumed to be exponential. A possible interaction term of the both predictors was considered, but again did not lead to an improvement in the model fit.It was also investigated to what extent this analytical function fits the test data described above. This resulted in The Article also contained an error in Fig. y axis) and the simulated ground truth (x axis). Each boxplot shows the 25th and 75th percentiles as well as the median, and the whiskers’ length is 1.5 times the interquartile range. For better visibility, the y axis is clipped at y = 30; predicted values outside this limit are displayed just on the limit. The numbers for the medians and standard deviations can also be found in Table 2.”“Graphical comparison of the predicted capillary diameters (now reads:y axis) and the simulated ground truth (x axis). Each boxplot shows the 25th and 75th percentiles as well as the median, and the whiskers’ length is 1.5 times the interquartile range. For better visibility, the y axis is clipped at y = 24; predicted values outside this limit are displayed just on the limit. The numbers for the medians and standard deviations can also be found in Table “Graphical comparison of the predicted capillary diameters  is reflected back into the skin by the stratum corneum. This relationship is exponential: With increasing values for When predicting the intercept In addition, the positions of the cross-sectional planes serving as the data basis for the The observation that the stratum corneum forms an optical boundary layer that prevents photons from entering or leaving the tissue is a key finding that does not only affect SP-DRI, but is likely to impact many other optical measurement techniques that are applied directly to the surface of the skin.”now reads:“From an optical point of view, these outermost skin layers thus serve as a boundary: On the one hand, photons emitted to the skin are reflected directly at or in these skin layers and thus do not or barely penetrate the skin. On the other hand, light that has been diffusely scattered in deeper skin layers and that is on its way back to the skin surface (i.e. to the detector) is reflected back into the skin mainly by the stratum corneum, but also by the epidermis. This relationship is exponential: With increasing values for When predicting the intercept In addition, the positions of the cross-sectional planes serving as the data basis for the The observation that the stratum corneum together with the epidermis form an optical boundary layer that prevents photons from entering or leaving the tissue is a key finding that does not only affect SP-DRI, but is likely to impact many other optical measurement techniques that are applied directly to the surface of the skin.”“If the influence of the stratum corneum can be eliminated when determining the parameters now reads:“If the influence of the stratum corneum and the epidermis can be eliminated or estimated when determining the parameters In the Conclusion,“A variation in The insight that the stratum corneum forms an optical boundary layer might not only affect SP-DRI, but is likely to impact many other optical measurement techniques that are applied directly to the surface of the skin.”now reads:“A variation in The insight that the stratum corneum and the epidermis form an optical boundary layer might not only affect SP-DRI, but is likely to impact many other optical measurement techniques that are applied directly to the surface of the skin.”The original Article has been corrected.


Introduction Maxillary canines are the most commonly impacted teeth, second only to third molars. Cleft lip and palate patients have a higher chance of impacted canines due to defects in bone formation and the soft tissue enclosing it. Various authors have used two-dimensional radiographs and developed grading systems to streamline treatment modalities to deal with the impacted canines.Material and MethodsA study was conducted in the Department of Orthodontics and Dentofacial Orthopaedics. Children aged nine to 12 were selected for this evaluation based on both clinical and radiographic examination. Four different parameters were set to evaluate the impacted canine location. which was based on angulation, vertical height, root apex location, and defect area involved.ResultBased on these evaluations, a classification was developed by the present authors, and later the cases were assessed as per the new system that we named Kumar and Daigavane's (KD) Impacted Maxillary Canine Grading System which we developed to give us more clarity for treatment and prognosis for treatment of cleft lip and palate.ConclusionA three-dimensional evaluation is also advised for a better understanding of the impacted canines. Many of the shortcomings of the two-dimensional assessment can be diminished. This new grading system will improve cleft diagnosis and prognosis in patients with cleft lips and/or palates. The development of a tooth is slowed or stopped as a result of impaction. Various terms, including delayed eruption, primary retention, submerged teeth, impacted teeth, and so on, are used to describe impaction in the scientific literature. A canine is considered impacted if its eruption is halted after the root has formed completely, or if the contralateral tooth has erupted for at least six months after the same stage of development . The maxIn the case of congenitally absent lateral incisors, the canine may erupt mesially until it makes contact with the distal aspect of the central incisor root and emerges into the lateral incisor space. Therefore, upper permanent canines rely heavily on the guidance provided by the lateral incisor roots. Finding out which teeth are impacted is the most important part of treating clefts. This is due to the fact that canines are the most susceptible to damage, and their condition can be exacerbated by a wide variety of causes. The following are some of the clinical manifestations of canine impaction: incomplete eruption of the permanent canine or prolonged retention of the deciduous canine; inability to locate canine position through intraoral palpation of the alveolar process; absence of a normal labial canine bulge; presence of a palatal bulge; and delayed eruption, distal tipping, or migration of the canine. Maxillary canines that become impacted can be assisted in erupting and moving to the appropriate position in the dental arch with the help of surgery and orthodontics if they are detected early and treated promptly. In order to facilitate the treatment of affected canines, many authors have devised grading systems based on this two-dimensional radiograph. Orthopantomagram (OPG) had been used as a diagnostic tool for locating the impacted canine location by various authors.A number of authors in this field have been cited in the literature. The affected canine position can be reliably predicted based on the sector classification. Using OPG, the sector drew several reference lines in order to identify the faulty canine component. The absence of a craniofacial anomaly supports the use of this classification scheme. consistent with cleft cases. The first to include angular and linear measurements for the impacted canine in addition to vertical and horizontal ones were Ericson and Kurol et al. -11 caninThis grading system, developed by the authors Kumar and Daigavane, is specifically framed for cleft lip and palate cases where there is a scarcity of the born breach in the continuous alveolar ridge, absence or congenitally missing of anterior teeth that leads to the impaction of canine. The reason for the new grading system is that sector classification for impacted canines is used worldwide for non-cleft patients. The parameter for grading impacted canine is the midline of the central incisor and lateral incisor, the long axis of the tooth. In unilateral cleft lip and palate or bilateral cleft lip and palate cases this is not applicable due to a defect of the cleft area and missing or congenitally missing lateral incisor, so sector classification will provide the wrong prognosis for the impacted canine. The new grading system used bone defect area in grading as well as angulation of the canine and the vertical height in maxillary bone is measured from the occlusion plane. The degree and severity of malocclusion are more severe in cleft than in non-cleft patients. So there was an urgent need for a new grading system for impacted maxillary canine in patients with cleft lip and palate cases.A study was conducted in the Department of Orthodontic and Dentofacial Orthopaedics, Sharad Pawar Dental College, Sawangi, Wardha, in collaboration with the Department of Oral Medicine and Radiology. The ethical committee of the Datta Meghe Institute of Medical Sciences approved the study (Ref no. DMIMS (DU)/IEC/2020-21/260). The CLP patients were selected from the Smile Train outpatient department. The localization of the maxillary canine was based on both clinical as well as radiographic examination:For clinical examination, the following features were taken into consideration during evaluation: (1) absence of a normal labial canine bulge; in other words, either inability to locate canine position through intraoral palpation of the alveolar process or the presence of an asymmetry in the canine bulge noted during alveolar palpation; and (2) the presence of a palatal bulge. For the radiographic examination, a panoramic view was taken for evaluation of canine angulation, height, root apex position, and exposure of canine in the cleft defect.Canine AngulationThe FH  plane was constructed on OPG by drawing a line from orbital to porion on the right side and continuing to the left side, considered as a P1 reference plane, and the inner angle was measured between the long axis of the canine to the FH plane, considered as an A1 angle. The occlusion plane was constructed on OPG by drawing a line from the cusp tip of a maxillary molar on the right side to the maxillary molar on the left side, considered as a P2 reference plane, and the inner angle was measured between the long axis of the canine to the Occlusion plane, considered as an A2 angle  above the canine position; (2) above the 1st premolar; 3) above the 2nd premolar; (4) toward the lateral incisor. This coincided with the angulation of the canine with P1 and P2. The long axis of the canine is shown by a pink line coinciding with the long axis of the canine (point 1), 1st premolar (point 2), and 2nd premolar (point 3) (Figure  above thCanine exposure to the cleft defectThe outer border of the cleft defect area was drawn on OPG and the positions of canines within the cleft defect area were graded accordingly. Grade I is shown in red, Grade II in blue, and Grade III in green Figure .Based on these evaluations, A classification was set and later the cases were assessed as per the new classification system that gave us more clear onset Table .Grading the impacted canine as Grade IOn clinical examination, there will be the presence of a labial or palatal canine bulge at the alveolar process. The radiographic evaluation depicts a 90°±10° angulation of A1 and A2 measured from P1 and P2, suggesting that the canines are erect and stable on the occlusion plane. The vertical height of the impacted canine crown will be at a distance of 5 mm ±2 mm when measured from P2. The location of the root apex of the canine will be along the long axis of the canine. The tooth meets in the cleft defect but is completely impacted into the bone, leaving no exposure in the cleft defect. On observing these findings, it can be stated that the prognosis of this grade will be good for eruption and alignment of canines. As part of the suggested treatment plan, a soft-tissue window will be made and a thin layer of bone covering the crown of the canine will be removed. This will help the canine fit better in the occlusion.Grading the impacted canine as Grade IIOn clinical examination, there will be the presence of a labial canine bulge above the alveolar process and till the depth of the vestibule and in the palatal region, a palatal bulge is seen in the area between the rugae. The radiographic evaluation depicts a 45°±10° angulation of A1 and A2 measured from P1 and P2. Now, this can be near the lateral and away from the lateral incisor. The vertical height of the impacted canine crown will be at a distance of 10 mm ± 2 mm when measured from P2. The location of the root apex of the canine will be near the first premolar. Concerning the cleft defect area, the only crown of the impacted canine will be seen in the bony defect area when fully covered with the soft tissue of the palate. On observing these findings, it can be stated that the prognosis of this grade will be average for eruption and alignment of canine. The suggested treatment plan will be age-specific. Canine eruptions should be monitored with ABG before the age of 10-12 years. After 12 years of age, surgical exposure of the impacted canine and orthodontics adjusts with the alignment of the root in the bone near the cleft to utilise the graft.Grading the impacted canine as Grade IIIOn clinical examination, there will be the presence of a labial bulge above the depth of the vestibule and a palatal bulge beyond the rugae area. The radiographic evaluation depicts a 180°± 10°and above angulation of A1 and A2 measured from P1 and P2. The vertical height of the impacted canine crown will be at a distance of 15 mm ± 2 mm when measured from P2. The location of the apex will be above the 2nd premolar. Concerning the cleft defect area, the crown and 12 roots will be seen in the bony defect when fully covered with the soft tissue of the palate. On observing these findings, it can be stated that the prognosis of this grade will be poor for eruption and alignment of canines. The suggested treatment plan will be age-specific. ABG should be done with monitoring canine eruptions before 10-12 years. After 12 years of age, surgical exposure of impacted canine and orthodontics adjusts with the alignment of the root in the bone near the cleft to utilise the graft.Grading the impacted canine as Grade IVOn clinical examination, there will be an absence of any labial or palatal canine bulge. The radiographic evaluation depicts the distal angulation of A1 and A2 measured from P1 and P2. The vertical height of the impacted canine crown will be at a distance of above 15mm when measured from P2. The location of the apex will be towards the lateral incisors. Concerning the cleft defect area, only the 14th root apex of the impacted canine is in the bone while the rest will be lying in the bony defect area and covered with the soft tissue of the palate. On observing these findings, it can be stated that the prognosis of this grade will be hopeless for eruption and alignment of canines. In order to save time and get the functional occlusion done faster, the most likely treatment plan will be surgical extraction instead of trying to align the teeth.We can gain insight into the prognosis and plan the treatment protocol for these cases by implementing a more recent grading system for the evaluation of the impacted canine in CLP cases. We anticipate a swift approach to treating adult cleft cases with this new grading system. A three-dimensional evaluation is also advised for a better understanding of the impacted canines and their relationship to the surrounding structure. Many of the shortcomings of the two-dimensional assessment can be diminished by the three-dimensional evaluation of CBCT. However, since three-dimensional diagnosis units might not be available at all of the operational centers, this two-dimensional OPG-based evaluation will assist medical professionals in developing a plan for how to treat patients with cleft lips and/or palates.


Large matrix multiplications commonly take place in large-scale machine-learning applications. Often, the sheer size of these matrices prevent carrying out the multiplication at a single server. Therefore, these operations are typically offloaded to a distributed computing platform with a master server and a large amount of workers in the cloud, operating in parallel. For such distributed platforms, it has been recently shown that coding over the input data matrices can reduce the computational delay by introducing a tolerance against straggling workers, i.e., workers for which execution time significantly lags with respect to the average. In addition to exact recovery, we impose a security constraint on both matrices to be multiplied. Specifically, we assume that workers can collude and eavesdrop on the content of these matrices. For this problem, we introduce a new class of polynomial codes with fewer non-zero coefficients than the degree +1. We provide closed-form expressions for the recovery threshold and show that our construction improves the recovery threshold of existing schemes in the literature, in particular for larger matrix dimensions and a moderate to large number of colluding workers. In the absence of any security constraints, we show that our construction is optimal in terms of recovery threshold. Recently, tensor operations have emerged as an important ingredient of many signal processing and machine learning applications . These oA and B, i.e., recovery threshold, to recover the correct matrix product C.In this work, we focus on the canonical problem of distributing the multiplication of two matrices Coded matrix computation was first addressed in the non-secure case by applying separate MDS codes to encode the two matrices . In 5],,5], polyA and B. Very recently, the authors in [In ,18 two dthors in  proposedthors in , a discrthors in  focused thors in , but worthors in .non-zero coefficients in the polynomial [In the following, we propose a new scheme for secure matrix multiplication, which provides explicit evaluation points for the polynomial codes, but unlike the work in , is alsolynomial ,19. In alynomial ). As sucThis paper is organized as follows. In A and B be a pair of matrices over the finite field A and B and that up to T honest but curious helper nodes may collude to deduce information about the contents of A and B. To divide the work among the helper nodes, the matrices A and B are each divided into N denotes the number of servers to be employed   Assume (ii)  Assume Proof. (i)Since (ii)We see that□Remark 2.The remaining two cases lead to a contradiction and can hence never occur. Let T servers colluding if and only if the matrixT evaluation points. This is the same as condition C2 in [Each query is masked with a polynomial of the form on C2 in . BecauseProposition 4.The matrix Proof. Proposition 5.A set of elements of Proof. Fix a generator γ of Corollary 1.Let Considering the scheme as described in the previous section, we see that the responses are the coordinates of a codeword of a Reed–Solomon code. The polynomial that needs to be interpolated has degree at most Theorem 4.The scheme in Proof. S erasures. Since S is smaller than the minimum distance of the code, the full codeword and hence the interpolating polynomial can be recovered.□The responses can be considered as a codeword in an Similarly, we can use additional helper nodes to account for possible Byzantine servers whose responses are incorrect.Theorem 5.The scheme in Proof. B errors. Since The responses can be considered as a codeword in an Combining both theorems give us the following corollary.Corollary 2.The scheme in V, found by deleting the columns of The upper bound on the recovery threshold given by the maximum degree of the product tions in , as a baTheorem 6.Let The number N of non-zero terms in the product Proof. If Consider the following sets.We have K if Clearly, Suppose first that Furthermore,Hence In the case Finally, suppose that Therefore, Example 1.Let We will compute the product whose non-zero matrix coefficients are chosen uniformly at random over Define Note that the total number of non-zero terms in Suppose now that we have heme see . In thiss 50 see , the coeng MAGMA ) that thWe remark that for the case of no collusion, Theorem 6 does not yield an optimal scheme. The proposition below outlines a modified scheme with a lower recovery threshold if secrecy is not a consideration.Proposition 6.Define the polynomials:The following hold:For each The number N of non-zero terms in the product Proof. For each We haveThe distinct monomials arising in the product The recovery threshold of this scheme takes the same value as the recovery threshold of the poly-entangled scheme of Theorem 1 .We provide some comparison plots that highlight parameter regions of interest. In T, our new scheme outperforms the SGPD scheme. This comparison of the recovery threshold for the two schemes is well justified since they use the same division of the matrices and will have identical upload and download costs per server.In q is the field size. The requirements for our scheme outlined in Proposition 5 and Corollary 1 ) ,32.N distinct elements of The encoding complexity of our scheme comes at the cost of evaluating the pair of polynomials N evaluation points, when N unknown coefficients.The decoding complexity is the cost of interpolating the polynomial N points or interpolation of a polynomial of degree at most N). Therefore, we have the following statement.The cost of either polynomial evaluation at Proposition 7.The encoding phase of the scheme presented in  N).The decoding phase of the scheme presented in  N).The total upload cost of the scheme presented in The total download cost of the scheme presented in A and B contain confidential data, which must be kept secure from colluding workers. Similar to some previous work also employing polynomial codes for distributed matrix multiplication, we proposed to deliberately leave gaps in the polynomial coefficients for certain degrees and provided a new code construction which is able to exploit these gaps to lower the recovery threshold. For this construction, we also presented new closed-form expressions for the recovery threshold as a function of the number of colluding workers and the specific number of submatrices that the matrices A and B are partitioned into during encoding. Further, in the absence of any security constraints, we showed that our construction is optimal in terms of recovery threshold. Our proposed scheme improves on the recovery threshold of existing schemes from the literature in particular for large dimensions of A and a larger number of colluding workers, in some cases, even by a large margin.In this work, we addressed the problem of secure distributed matrix multiplication for


Optical camera communication (OCC), enabled by light-emitting diodes (LEDs) and embedded cameras on smartphones, has drawn considerable attention thanks to the pervasive adoption of LED lighting and mobile devices. However, most existing studies do not consider the performance bottleneck of Region of Interest (RoI) extraction during decoding, making it challenging to improve communication capacity further. To this end, we propose a fast grid virtual division scheme based on pixel grayscale values, which extracts RoI quickly without sacrificing computational complexity, thereby reducing the decoding delay and improving the communication capacity of OCC. Essentially, the proposed scheme uses a grid division strategy to divide the received image into blocks and randomly sample several pixels within different blocks to quickly locate the RoI with high grayscale values in the original image. By implementing the lightweight RoI extraction algorithm, we experimentally verify its effectiveness in reducing decoding latency, demonstrating its superior performance in terms of communication capacity. The experimental results clearly show that the decoding delay of the proposed scheme is 70% lower than that provided by the Gaussian blur scheme for the iPhone receiver at a transmission frequency of 5 kHz. As the demand for ubiquitous connectivity and high capacity increases , traditiOptical camera communication systems built on commercial off-the-shelf (COTS) equipment typically employ LED lighting infrastructure as transmitters and low-cost cameras as receivers. However, limited by the inherent conditions of low frame rate ) and the low sampling rate of ordinary cameras, the early works of OCC can only reach a data rate of several bytes per second ,19. To oAiming at addressing the problem of the small communication capacity of OCC, several methods have been proposed in prior works. T.H. Do and H. Lee et al. ,25 systeSince the camera can usually distinguish the color of the light, P. Hu et al.  used RGBThe traditional RoI extraction method first performs a grayscale conversion operation on the entire image received by the camera, followed by Gaussian blur and threshold discrimination to obtain the outline of the RoI. The decoder then extracts a row or column of pixels from within the contour to form a grayscale vector for subsequent demodulation and decoding to enable data communication. However, the realization of the Gaussian blur step needs to be filtered by building the corresponding weight matrix, which makes the entire Gaussian blur process very time consuming . In addiWe set up the background of RoI extraction in this section. First, we briefly introduce the rolling shutter effect of the CMOS camera embedded in the intelligent device. Then, provide a detailed explanation of why the Gaussian blur steps used in the traditional RoI extraction process are time consuming.In rolling shutter mode, the photodiode does not collect all the light simultaneously, but instead scans the pixels sequentially using the CMOS image sensor (IS). Images are generated by row by row (or column by column) scanning and exposing one row (or column) of pixels at a time, with each row (or column) pixel in the sensor array having a different time to start and end the exposure. Thus, the delay in the exposure time allows us to record the relative structure of the target based on time. In this mode, different pixels obtained from the rolling shutter image sensor have different light signal intensities, which means that there are multiple bits of information. Precisely, the receiver can capture multiple switching states of the illumination source in the image. When the LED luminaire is “ON”, a bright stripe is generated in the image, representing the binary data “1”, and when the LED luminaire is “OFF”, a dark stripe is generated in the image, representing the binary data “0”, as shown in As mentioned previously, the rolling shutter mechanism adopts a sequential exposure method, displaying the “ON” and “OFF” status of the illumination source as stripes in the image. Only these stripes carry valid data information sent by the transmitter. Therefore, the extraction of the striped area (RoI) is a core factor affecting the performance of OCC. While one can quickly identify RoIs in images with the naked eye, automatically extracting them via a smartphone is by no means trivial due to the spatial distribution of transmitters. Existing work ,34 typicx and y represent the horizontal ordinate distance from the point to be calculated to the center of the convolution kernel, respectively. As illustrated in According to the Gaussian function, the weight value of each pixel in the image received by the surveillance camera is calculated, and the weight matrix is normalized. For each pixel of the original communication image, the product of its neighborhood pixels and the corresponding elements of the weight matrix are calculated and then summed to obtain the Gaussian blur value of the current center pixel. The weight matrix is then shifted to the right to calculate the Gaussian blur value for each point. Obviously, the contour extraction technique in OpenCV needs to traverse each pixel in the received image, resulting in high computational complexity and time consumption during OCC decoding. However, most indoor lighting currently employs round, square or rectangular LED luminaires. It is relatively simple to extract the contours of these LED luminaires compared with the complex contour extraction in the field of CV. Therefore, we only need to iterate through part of the pixels rather than all of them for quick positioning, which will effectively diminish the decoding delay of the OCC receiver and strengthen the communication capacity of the OCC.In this section, we explain the overall design of the grid virtual division scheme based on the OCC system. We start with a brief overview of the OCC system workflow, and then we discuss its individual components in detail. Finally, we highlight the detailed steps of the grid virtual division scheme in the OCC receiver.As illustrated in The light sources used in daily life include halogen lamps, incandescent light bulbs, fluorescent lamps and LEDs. Only LEDs are perfect light sources for optical camera communication due to their fast rate of ON–OFF switching. Therefore, we generally use white light LED luminaires as the transmitter device of OCC. The workflow diagram of the OCC transmitter is shown in the upper part of ith row and jth column pixel. Finally, the grayscale information obtained after sampling is converted into logical data by setting thresholds to distinguish different grayscale value levels of the transmission signal.As illustrated in the lower part of RoI extraction is the core factor affecting communication performance, but the existing RoI extraction technique is computationally complex and time consuming. Taking these issues into account, we suggested a grid virtual division scheme that improves the efficiency of RoI extraction. Since the light emitted by the transmitter is brighter, the area where the RoI projected by the transmitter in the received image has a higher grayscale value of the pixels than the area where the non-RoI is located. Suppose a pixel with a high grayscale value is retrieved in a certain area, and there are still pixels with a high grayscale value in the positive and negative ten pixels on both sides of the point. In that case, it proves that the area is an RoI area with adjacent symbols. Therefore, the proposed scheme considers using the grayscale values of the pixels in the received image to quickly locate these RoIs. In this section, we employ three shapes of LED luminaire—round, square, and rectangular—as transmitters. The RoI projected by the transmitter carries desired information in a frame, as shown in Step 1—Image Chunking: When the CMOS camera receives a whole image containing optical communication information, the proposed scheme first establishes a virtual grid of the original image, as shown in the virtual grid composed of orange dotted lines in R represents a collection of grayscale values for randomly sampled pixels within different grids, n of row m in the ith block, k represents the number of blocks divided into the original image, Step 2—Pixels Sampling: After the virtual grid is established, the decoder randomly samples the grayscale values of several pixels within the block from the uniform distribution. Since the area after grid division is small, if the RoI is located in that area, it is likely to produce a larger area of coverage within the block. Therefore, we sample the pixels in the left, middle and right areas of the middle row in each block to increase the hit rate of RoI detection in the block. To be specific, we first choose to randomly sample a pixel in the left area. If the pixel meets the requirements, we will directly save the block number and continue to process the next block. If the pixel does not meet the criteria, we will continue to perform the same operation in the following area until all three areas are completed. As mentioned before, the grayscale value in the area where the optical signal is concentrated is higher than that in the surrounding area. To better distinguish which sampled pixels are eligible, we set a grayscale threshold empirically so as to maximize recognition accuracy. For comparison with this threshold, in this step, we first store the sampled grayscale values in the collection, which are represented as follows:n and m to locate this area quickly. To be precise, the pixels sampling step calls the SEARCHPIXEL and SAMPLE functions in Algorithm 1 after the virtual grid has been established in the frame. SEARCHPIXEL function filters the randomly sampled pixels in the SAMPLE function and stores the block number that meets the requirements in the results container. As mentioned before, we sample the pixels in the left, center and right areas of each block’s middle row. As illustrated in Algorithm 1 Grid virtual division algorithmInput: n, m, Output: 1:functionSearchPixel plus “6” (number of columns) in Step 4—Demodulation and Decoding: Once the coordinates are obtained, this step involves converting the grayscale to bits and recovering the transmitted data. To be more specific, the demodulator first samples a single row or column of pixels from the acquired area to form a grayscale sequence for demodulation. In order to identify the start of a transmission session, the demodulator first uses a coarse-grained threshold to distinguish the preamble, which is defined as several consecutive bright symbols in the packet. Subsequently, fine-grained thresholds are fitted using the grayscale information of the identified preambles to further convert the grayscale information between two adjacent preambles into logical data. Finally, the receiver recovers the sent messages and completes the decoding process of a whole frame.n denotes the size of the data and n, so the space complexity is In a nutshell, the above four-step implementation enables the OCC system to locate RoIs with high grayscale values without traversing all pixels. Since it is necessary to traverse the container storing the block numbers of high grayscale values, the time complexity of the algorithm can be calculated as In this section, we first introduce hardware and software implements of the proposed OCC system. We then report the experimental results of the proposed OCC system with the grid virtual division scheme. To verify the effectiveness of the proposed scheme, we conclude by seriously discussing various metrics and providing some insights into further improvements of the performance of OCC.In order to evaluate the performance of the proposed OCC system with the grid virtual division scheme, we build four prototype systems and demonstrate its experimental setup, as shown in Based on the prototype of the experimental system already deployed in Since extraction time is a core indicator used to measure the efficiency of RoI extraction, in this subsection, we first explore the performance of the proposed scheme in terms of processing time under varying transmission frequencies. Specifically, the processing time is the elapsed time from when the receiver captures an image to when the RoI extraction is completed. In addition, we also examine the performance of the traditional scheme and the proposed scheme in terms of BER under varying transmission frequencies. We present the experimental results of each group and analyze them in the following sections.We fix the receiver at a distance of 80 cm away from the No.1 transmitter (round LED with a diameter of In addition, we also report the BER results obtained by iPhone 8 Plus under three different transmission frequencies, as shown in As a practical communication, the various shapes and sizes of LEDs supported by OCC can have an impact on the efficiency of RoI extraction. Therefore, we evaluate the performance of the traditional and the proposed schemes in terms of processing time and BER based on LEDs of different shapes and sizes in this subsection. More specifically, we configure the transmission frequency at 5 kbps and fix the receiver at a distance of 80 cm away from the transmitter to measure the extraction efficiency of both schemes. As shown in Similar to the work in As mentioned earlier, the number of transmitters projected in a frame affects the extraction efficiency of the RoI to a certain extent. Therefore, in this subsection, we explore the performance of the traditional and proposed schemes under variable LED numbers. We still configure the transmission frequency at 5 kbps and fix the receiver 80 cm from the transmitter to measure the processing time and BER of both schemes. Specifically, we increase the number of transmitters of the same shape and size from one to four in turn. The experimental results are presented in As shown in To cope with the issue of the performance bottleneck of RoI extraction during decoding, in this paper, we present an OCC system based on a fast grid virtual division scheme, which is purely built on COTS devices to improve OCC performance further. Essentially, the proposed innovation scheme establishes a virtual grid of size