After that, all selected participants were administered a speaking anxiety questionnaire and a motivation questionnaire as the pre-test of the research. Then, one of the experimental groups received an online-based instruction via Skype: one conversation was instructed to this group online every session. The other experimental group received the treatment via flipped-based instruction. The audio files and the texts of the conversations were sent to this group via the WhatsApp application because they all had easy access to it. On the other hand, the control group did not receive any Internet-delivered treatment yet was trained through a face-to-face method. This process continued until the last session, and after the treatment period, the post-tests of speaking anxiety and motivation were given to all three groups to determine the effectiveness of the treatment. Moreover, two attitude questionnaires were administered to the experimental groups to examine their attitudes toward the MOOC and the flipped models of instructions. The findings of the One-way ANOVA test, Post-hoc Scheffe test, and paired samples t-test showed that there were significant differences between the post-test of the experimental groups and the control group. The results indicated that the experimental groups significantly outflanked the control group after the treatment. Lastly, the outcomes showed that participants in both experimental groups had positive attitudes toward technological-based instructional environments.This study inspected the effect of Massive Open Online Course (MOOC) and flipped instruction on EFL learners’ foreign language speaking anxiety, foreign language learning motivation, and attitude toward English learning. To fulfill this objective, the Oxford Quick Placement Test was given to 160 Iranian EFL learners, of whom 120 upper-intermediate participants were chosen and divided into two experimental groups—MOOC ( Language learning is getting easier than before thanks to the miracle of the century—technology. Nowadays, different kinds of technology tools are seen everywhere, and they are frequently used in English language learning. One branch of technology is Massive Open Online Course (MOOC) that refers to online courses with free and open registrations, a publicly shared curriculum, and open-ended consequences. Using MOOCs as an instructional instrument can provide a rich and varied learning context characterized by learners’ interactions from diverse locations. Its participatory, open, and innovative techniques supply new methods for the learners to learn in virtual learning environments . MOOC isvia a better allocation of teaching time  explained above can be influenced by the online instructional methods of MOOC and flipped. Based on via flipped-based instruction, but the control group was trained via conventional instruction.To perform this investigation, the Oxford Quick Placement Test (OQPT) was administered to 160 Iranian EFL students, and 120 of them were chosen for the target population of the research. The subjects were chosen from three English Language Institutions of Esfahan city, Iran, at the upper-intermediate level. They were all male students because only males were accessible to the researchers. The chosen respondents were randomly divided into two experimental groups and a control group. One of the experimental groups was taught based on the MOOC instruction, and the other experimental group was instructed The first tool applied in the current research was the OQPT which aided the researchers in choosing the homogenous students. This test had 100 items designed by the Oxford University Press and the University of Cambridge Local Examinations Syndicate. The test was validated in 21 countries by more than 7,000 learners, and its reliability reached 0.91 . This tovia utilizing Cronbach Alpha (r = 0.88).The second instrument utilized in this research was the Speaking Anxiety Scale (SAS) that was an 18-item questionnaire extracted from r = 0.85). It should be noted that the SAS and the MTB questionnaires were utilized twice in this research: once as the pre-test and once as the post-test.The third instrument employed in this study was a questionnaire extracted from r = 0.86).The other tool employed in the current investigation was an attitude questionnaire admonished to the MOOC group to examine their ideas about MOOC-based instruction. This tool was made by the researchers and had 20-point Likert-type items. The researchers computed the reliability of this tool by using Cronbach’s alpha (r = 0.83). It is worth mentioning that some English professors confirmed the validity of both attitude questionnaires.The fifth tool employed in the current investigation was a questionnaire given to the flipped participants to examine their opinions toward utilizing flipped classrooms. The questionnaire of via the MOOC program to the participants of this group. In the MOOC-based class, both teachers and students simultaneously worked in a learning context. The researchers set an exact time for an online class, and participating for all participants was an obligation. The students chatted and discussed the materials in an online setting. Everything was done on the online platform. It must be stated that after the instruction, a questionnaire was administered to the MOOC respondents to examine their opinions about MOOC instruction implementation.To perform this research, 120 homogenous participants were chosen and divided into three groups of 40: two experimental (MOOC and flipped) and a control. Then, the questionnaires of MTB and SAS were administered to examine the motivation and speaking anxiety of the respondents before starting the instruction. After that, one experimental group received the treatment by using an online-based instruction-MOOC. In every session, one conversation was instructed via the WhatsApp application, and they were accountable for their own learning. The participants of this group were asked to study the materials before coming to the real class. Three or four days before each face-to-face class, the researcher sent the audio files and the texts of the conversations to students via the WhatsApp application. The learners were asked to read and practice the conversations prior to attending the classes. After attending the class, the researcher extracted some information pertinent to the conversations from students. Moreover, some students were randomly chosen to conduct the conversation in front of the class. A questionnaire was given to examine the flipped participants’ ideas about applying the flipped instruction when all conversations were taught.The flipped group was sent the materials (conversations) The control group participants were traditionally instructed the conversations without using any online instruction. First, the researcher provided the students with some information about the topic of the conversation, and then, he played the audio file two or three times; after listening to the audio file and teaching each conversation, the participants were wanted to practice it with their classmates and carry it out in front of the students. After teaching 10 conversations, the questionnaires of MTB and SAS were readministered to investigate the influences of the instruction on the pupils’ motivation and speaking anxiety.via the pre-tests, the post-tests, and the questionnaires, they were analyzed using the SPSS software, version 22. Firstly, the One-way ANOVA test and Post-hoc Scheffe test were employed to analyze the performances of the three groups before and after the treatment. Secondly, a One-sample t-test was applied for analyzing the data collected via the attitude questionnaires.After gathering the data Nowadays, the growth of technology and the incorporation of new technological attainments are observed in our daily lives . TechnolOne technological-based teaching is flipped instruction which has gotten significantly common in educational contexts, and they more universally utilized by instructors in the past several decades ; it is uThe flipped classroom can be considered as a kind of student-centered learning since students are responsible for learning independently by flipped materials facilitated by instructors and boosting more participation in discussions and research activities in the classrooms . In thisThe other technological-based teaching is MOOC which is a desirable mode of instruction. As its name shows, MOOC is a method in which instructional content is presented online to those students who have online courses, without limitations on attendance . MOOC isvia specific actions. Based on Massive open online course and flipped instructions can help EFL learners to raise their foreign language learning motivation. EFL learners’ motivational orientation is the psychological condition that shows their needs, desires, and aims to learn a target language expressed In addition to motivation, EFL learners’ foreign language speaking anxiety can be influenced by new teaching methods, such as MOOC and flipped instructions. Anxiety can facilitate and impede the language learning process . To dateHaving less anxiety during learning can assist EFL learners in having positive attitudes toward English language learning. Attitude has lately received much attention from both first and second language scholars. The majority of the studies on the issue concluded that students’ attitudes are a crucial part of learning and must become an integral part of second or foreign language learning pedagogy. There are some reasons why investigating students’ attitudes toward language learning is significant. First, attitudes toward learning are supposed to affect behavior . Second,In this part, some experimental studies on the effects of the MOOC and the flipped instructions on developing language learning are reported. For example, via applying MOOC instruction. To reach this aim, 32 subjects from two countries of Mexico and Colombia were chosen. At the beginning and the end of the treatment, the subjects were required to answer a questionnaire encompassing the General Self-Efficacy Scale, items on specific study skills, and space for non-mandatory comments. The results displayed a noticeable improvement in general self-efficacy after the treatment and the perceived self-efficacy pertinent to five out of six study skills. The outcomes also indicated that MOOCs could represent low-risk, formative opportunities to enhance the respondents’ knowledge and improve self-efficacy.Recently, via flipped-based instruction, but the traditionally trained non-flipped participants. At the end of the treatment, an attitude questionnaire was given to the flipped participants to check their opinions about applying to the flipped classroom. The outcomes proved that the flipped group did better than the non-flipped group on the speaking post-test. In addition, the findings revealed that the participants presented desirable attitudes toward using flipped instruction in English language learning.After reviewing the related literature, it was revealed that most investigations inspected the influences of the MOOC and the flipped instructions on vocabulary, reading skills, and speaking skills. There are few experimental investigations on the MOOC’s effect and flipped instructions on Iranian EFL learners’ speaking anxiety and foreign language learning motivation. Thus, the below questions were formulated to cover this gap.RQ1. Does MOOC instruction bear any significant impact on Iranian EFL learners’ speaking anxiety and foreign language learning motivation?RQ2. Does flipped instruction bear any significant impact on Iranian EFL learners’ speaking anxiety and foreign language learning motivation?RQ3. Do Iranian EFL learners have positive attitudes toward using the MOOC instruction in learning the English language?RQ4. Do Iranian EFL learners have positive attitudes toward using flipped instruction to learn English?In this section, the collected data were analyzed, and the gained results are presented in the following tables:via the anxiety questionnaire administering before and after the treatment were analyzed in this part.The data gathered p < 0.05). Indeed, the three groups had the same level of speaking anxiety before the treatment.Based on The above table indicates that the mean score of the control participants is 45.37, the mean of the flipped participants is 72.27, and the mean score of the MOOC group is 70.95. Based on p < 0.05). Moreover, the outcomes show that there were no significant differences between the scores of both experimental groups in the anxiety post-tests.–The following Table 5p < 0.05); besides, the results indicate that there was not a remarkable difference between the motivation post-tests of both experimental participants.In via the MOOC questionnaire were analyzed to check Iranian EFL learners’ attitudes toward the MOOC instruction.In this section, the data collected As revealed in In this part, we analyzed the data gathered through administering the flipped questionnaire after the treatment to examine the participants’ attitudes toward flipped instruction.As displayed in Regarding the first question of the study, the results showed that the experimental participants who had received MOOC instruction outflanked the control participants who had been deprived of the MOOC instruction. This improvement and betterment can be attributed to the MOOC instruction since it can save time and effort. MOOC instruction was open to students and gave them more opportunities to express themselves.via MOOC, more rooms can be provided for the students to share their ideas and knowledge. Also, MOOC-based instruction can supply comfortable contexts for learners to establish interactions and communications with their classmates and instructors. In addition, in a MOOC-based setting, learners can access the material and feedback even long after the course  can use the MOOC and the flipped instructions to compensate for their absence. The MOOC and the flipped instructions make the students responsible for their own learning. By supplying lectures online, instructors can pave the way for the learners to learn the lessons at their own speed. This research can assist those learners who have embarrassment in participating in face-to-face classes. In addition, the outcomes of this research can persuade the material designers to integrate online instructions into EFL syllabuses.Though we try to conduct this research ideally, drawbacks are unavoidable in any empirical investigation. Including a small sample (120 Iranian upper-intermediate EFL students) was the main limitation of this study; therefore, we should generalize the results to other populations carefully. Further studies can include more participants to get richer findings. Only quantitative instruments were used to collect the data for answering the research questions; upcoming research is proposed to apply both qualitative and quantitative instruments to boost the reliability and validity of the results. The subjects of this study were only males; future studies are recommended to include females, too. Future investigations can expand the treatment time and investigate the effect of the MOOC and the flipped instructions on different skills in different settings.The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/supplementary material.All authors listed have made a substantial, direct, and intellectual contribution to the work, and approved it for publication.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.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


E must be under 3%, and the sensor must achieve an f-number of 8.0 concerning the light source. The following main innovations have achieved this: an Ulbricht sphere providing a uniform light distribution (irradiation) of 99.54%; an innovative illuminator with proper positioning of color Light Emitting Diodes (LEDs) and control electronics; and a flexible C# program to analyze the sensor parameters, namely Quantum Efficiency, Overall System Gain, Temporal Dark Noise, Dark Signal Non Uniformity (DSNU1288), Photo Response Non-Uniformity (PRNU1288), Maximum achievable Signal to Noise Ratio (SNRmax), Absolute sensitivity threshold, Saturation Capacity, Dynamic Range, and Dark Current. This new instrument has allowed a camera manufacturer to design, integrate, and inspect numerous devices and camera models .This paper presents the development of a hardware/software system for the characterization of the electronic response of optical (camera) sensors such as matrix and linear color and monochrome Charge Coupled Device (CCD) or Complementary Metal Oxide Semiconductor (CMOS). The electronic response of a sensor is required for inspection purposes. It also allows the design and calibration of the integrating device to achieve the desired performance. The proposed instrument equipment fulfills the most recent European Machine Vision Association (EMVA) 1288 standard ver. 3.1: the spatial non uniformity of the illumination Δ Cameras are essential systems in human-machine interactions because vision provides about 80% of the necessary information for life. This paper deals with evaluating the electronic response of images or, more generally, light or camera sensors. These optical sensors are compact devices capable of analysis using a receptor. An optical transducer converts light or photons into an electrical signal ,2. TheseA stable, accurate, and consistent evaluation of the electronic response of a light sensor is required both for inspection (go/no-go testing) and for the characterization and correction of its response at different phases of the integrating device development process, as summarized in Such devices have a potential market among sensor manufacturers, sensor integrators, and final users of the integrated product. As shown in -As an individual component during the sensor manufacturing for process control or before delivery.-During the manufacturing of the integrated product , after supply by acceptance testing or sampling, at various assembly stages, and final testing.-By the system integrator  for the firmware/software development and the final testing of the integrated system.-By the final user  for setup, maintenance, and periodic calibration.Inspection or quality assessment can be considered as a sub aspect of the sensor characterization. In this activity, the actual response is compared to the given specification set a priori. As shown in During the development of a product integrating a sensor, its electronic response is required to develop the interfaces and the rest of the electronics. The characterization of the electronic response in different conditions is also helpful to achieve the desired sensor behavior ,5,6.The electronic response of a sensor is included as technical datasheets accompanying the product. Sometimes, it requires validation by the customer, e.g., in the case of low cost products, different batches coming from external manufacturing plants, or inconsistent production. Cameras having the exact same specification datasheets may behave completely differently when viewing the same scene. Datasheets can also be biased, showing only the best qualities and characteristics of the product. For example, it is common to indicate the number of bits of the onboard Analog to Digital Converter (ADC), even though in reality, only a subset of the available bits will be used. The technical analysis of the camera can be done by the device manufacturer unbiasedly by standardizing the test process, allowing to compare the camera performance with respect to noise, dark current, sensitivity, gain, linearity, and other parameters.standard 20], measarly, in , an expestandard is offered but no specifications are reported about the equipment. Commercial solutions are also available on the market. For example, in  a servicstandard requirements, a real complete hardware and software system implementation seems not yet available. The main contribution of this paper is a systematic analysis of possible approaches and a validated conceptual solution to fill this research gap.Despite the existing standard, more briefly referred to just as “The standard” in the remainder of this paper, provides a unified method to measure sensors and cameras for their characterization and comparison [The EMVA 1288 standard was promoted by a consortium of camera manufacturers and stems from creating a protocol to uniquely determine the significant functional parameters and thus simplify consumer choice. It provides the standard for measurement and presentation of specifications for machine vision sensors and cameras. In particular, release 3.1 covers monochrome and color digital cameras with linear photo response characteristics [standard text, split into four sections, describes the mathematical model and parameters that characterize cameras and sensors: linearity, sensitivity, and noise for monochrome and color cameras; dark current; sensor array non uniformities; and defective pixel characterization.The eristics . The seneristics . The stastandard presents an overview of the required measuring setup that is not regulated, not to hinder progress and the ingenuity of the implementers. Finally, the camera being tested can be described by the mathematical model on which the standard is based. The general assumptions include:-The sensor is linear, i.e., the digital output signal increases linearly with the number of photons.-E (units W/m2) and exposure time expt (units s), i.e., the radiative energy density expE*t at the sensor plane.The number of photons collected by a pixel depends on the product of irradiance -All noise sources are wide sense stationary and white concerning time and space. In other words, the parameters describing the noise are invariant with respect to time and space.-Only the total quantum efficiency is wavelength dependent. Therefore, the effects caused by light of different wavelengths can be linearly superimposed.-Only the dark current is temperature dependent.The These assumptions represent the properties of an ideal camera or sensor. If the deviation is slight, the description is still valid, and the degree of variation from an ideal behavior can be described. However, if the deviation is too large, the characterization is meaningless since camera parameters deviate from one of these assumptions.standard can be summarized as follows: the photons reaching the sensor are converted into electrons according to a percentage given by the quantum efficiency η. Therefore, a disturbance is added in the form of electrons, not photo generated, but caused by thermal agitation in the sensor. Then the signal is amplified and sent to an ADC that introduces its own quantization quantization noise. Finally, the signal coming out of the ADC represents the digital image on which the probabilistic calculations can be performed.The mathematical model proposed by the The proposed instrument was built around an integrating sphere, also known as an Ulbricht sphere . The renThe measurement system has the following main components and is described in more detail in the following sections.-Sphere : ①–②: di-Photodiode circuit : ⑬ to be-Illuminator with three Red, Green, and Blue (RGB) LEDs controlled via an FT232BL chip converting Universal Serial Bus (USB) to RS232 serial connection from the PC, detailed in . The LED-standard tests : controls the on/off switching of the individual LEDs of the illuminator, receives the grabbed images, processes images, and provides a report with numerical information, including the graphs required by the EMVA 1288 rd tests .As for the construction of the hardware prototype, the sphere element : ①–② hasAs for the electronic circuitry, the measurement system includes the photodiode drive circuit used for photon counting. The 3D CAD model of the chassis and conditioning circuit is shown in The Vishay BPW34 photodiode  is commo2) can be thus calculated. Knowing the wavelength (and therefore the energy) of the individual photons emitted by the illuminator, it is possible to obtain the average value of the number of incident photons on each pixel of the sensor.The current generated by the photodiode D1 in  under ilThe resistors A in The other element of electronic circuitry is the illuminator. The one adopted presents a set of RGB LEDs. The rendered 3D CAD model image is shown in The driving system of the illuminator consists of a PIC that receives commands from a PC via a USB-RS232 converter F in  and manaThe software allows selectively turning on the three LEDs on the board and adjust the light intensity. The illuminator includes bracket C in The main interface of the program that supervises the instrument tests can be seen in The camera characterization requires many samples, allowing accurate evaluation of the camera properties.The inspection mode is used in production with lower testing time.standard  and Photo Response Non Uniformity (PRNU1288) [According to the developed Graphical User Interface (GUI), all the tests can be performed at once or, according to the utton in  represenutton in . The Secutton in  calculatutton in . The Secutton in  can be ustandard [The testing method follows Chapter 6 of the EMVA 1288 standard. According to the standard, the tests are carried out with fixed illumination and using the analysis mode, taking 50 sample images. Fifty camera models have been developed using this instrument and its evolution over ten years. Sensors not compliant with the manufacturer’s blemish specifications have been rejected. Cold/hot pixels have been fixed, and unknown issues have been solved using a wide range of tests and analyses derived from the EMVA 1288 standard does not mandate the use of a climate chamber; the control software is designed to keep the LED on for about 150 s before running the tests to reach the thermal equilibrium. The light intensity dependence from the temperature has been experimentally investigated, as shown in The camera operates at a constant temperature of 30 °C  set on the camera. Supposing that the granularity of the exposure time setting is not a submultiple of the unit of measurement, a “sawtooth” trend results for espt. This peculiar trend requires a firmware upgrade.espt control. The identified pattern  sensors.standard ver 3.1; an innovative illuminator with proper positioning of RGB LEDs and control electronics as described; and a flexible C# program to analyze the sensor parameters also presented.Among the main innovations vs the state of the art are the design of an Ulbricht sphere providing a uniform light distribution fulfilling the EMVA 1288 standard ver 3.1 are the Quantum Efficiency, Overall System Gain, Temporal Dark Noise, DSNU1288, PRNU1288, SNRmax, Absolute sensitivity threshold, Saturation Capacity, Dynamic Range, and Dark Current.The paper has shown that using the proposed instrument. It is possible to carry out a complete and reliable characterization of the specific parameters of the sensor used. This allows a more informed choice of sensors based on their actual performance and calibration. The considered parameters indicated by the current The proposed instrument has been applied for ten years to characterize the integration and to inspect over fifty camera models by Alkeria. Validations have been carried out by direct measurement and indirectly by comparing data sheets of different sensors and similar camera models on the market.-A calibration procedure for verifying the effects of hardware and software changes of the camera in real time. This can be achieved using an iterative testing method in the design phase that allows tweaking the hardware by quickly converging towards an optimal solution.-Using a real radiometer instead of the Vishay photodiode would allow the certification of the results produced and greater accuracy in detecting the number of photons incident on the sensor.-Extending the spectral analysis using a series of LEDs at different wavelengths or a broad spectrum illuminator with a bank of filters at set wavelengths, particularly for color sensors.-Addition of a temperature sensor and control to increase the instrument productivity, speed up the LED warming, and prevent the risk of overheating. This would also allow characterizing the dependence of the dark current on the temperature.-Scaling the instrument in size by a modular design accommodates the downsizing of sensors, e.g., by additive manufacturing for design and part replacement flexibility and checking the potential effect of geometric accuracy .Among the potential instrument improvements are:


Terahertz (THz) imaging techniques are attractive for a wide range of applications, such as non-destructive testing, biological sensing, and security imaging. We investigate practical issues in THz imaging systems based on a solid immersion lens (SIL). The system stability in terms of longitudinal misalignment of the SIL is experimentally verified by showing that the diffraction-limited sub-wavelength beam size (0.7 λ) is maintained as long as the SIL is axially located within the depth-of-focus (~13 λ) of the objective lens. The origin of the fringe patterns, which are undesirable but inevitable in THz imaging systems that use continuous waves, is analytically studied, and a method for minimizing the interference patterns is proposed. By combining two THz images obtained at different axial positions of the object and separated by λ/4, the interference patterns are significantly reduced, and the information hidden under the interference patterns is unveiled. The broad applicability of the proposed method is demonstrated by imaging objects with different surface profiles. Our work proves that the resolution of conventional THz imaging systems can easily be enhanced by simply inserting a SIL in front of the object with high tolerance in the longitudinal misalignment and provides a method enabling THz imaging for objects with different surface profiles. Terahertz (THz) imaging has proven its usefulness in various fields, such as non-destructive testing (NDT), biological sensing, and security imaging . One proOne technical issue that plagues THz imaging is its poor spatial resolution compared with infrared and visible imaging due to its long wavelengths (1 THz = 300 μm). Efforts have been made to achieve sub-wavelength images in the THz region. Nanoscale resolved THz near-field microscopy was reported by Huber et al. in 2008 . They acIn addition to the above-mentioned techniques, a sub-wavelength imaging technique based on a solid immersion lens (SIL) is intriguing. The SIL-based imaging technique utilizes an additional high refractive index lens between the objective lens and the object to obtain more confined electromagnetic waves near the original focal plane formed by the objective lens . This teWhen the SIL is inserted between the objective lens and the sample, understanding the system stability in terms of the longitudinal misalignment of the SIL is critical, as the focus shift from SIL misalignment would defocus the sharply converging beam on the SIL-air interface. The defocus can make the beam return to the original size obtained in the imaging system without the SIL . HoweverAlthough soft biological tissues have been successfully imaged with a THz SIL imaging system utilizing a Si wafer on which the imaging objects are placed , air gapThe experimental schematic is shown in A hemispherical Si lens with a radius of 5 mm was used as a SIL to reduce the beam size and improve the image resolution. The planar surface of the hemispherical Si lens is located at the focal plane of the objective lens. Thus, the spherical surface of the lens is concentric to the converging THz wavefront of the original wave without an Si lens . The objFirst, we define the DoF of the THz beam on the image plane without the SIL. To define DoF, beam profiles were obtained at different axial positions, and the focus measures of the images were calculated at each position accordingly. The beam profile images at different axial positions are illustrated in I represents the intensity of the image with the pixel coordinate .The focus measure functions compute the intensity difference between two adjacent pixels and are used for autofocusing and defining the DoF in various imaging systems ,27,28,29λ is the wavelength, n0 is the refractive index of air, and NA is the numerical aperture of the objective lens. The focus measure and normalized maximum intensity values oscillate as a function of axial positions, and this has also been reported in other THz imaging systems that use a quantum cascade laser (QCL) [As shown in er (QCL) . ConsideThe stability of the THz SIL imaging system in the case of the longitudinal and transverse misalignment of optical components has been studied using FDTD simulations . The simα and z = zβ (opposite ends of the DoF) are shown in We characterized the beam properties when the Si lens is inserted at different z positions within the DoF of the objective lens to experimentally verify the stability of the optical system with respect to the longitudinal displacement of the Si lens. First, the detector was positioned to detect the maximum THz intensity for each z-position. Then, the Si lens was aligned to maximize the detected THz intensity, thereby to minimize the transverse displacement. Following this process, THz beam profiles were obtained by changing the axial position of the detector. A schematic of beam focusing with the Si lens is shown in To estimate the beam size  change due to the misalignment of the Si lens, a test object  were obtained. The THz imaging areas are indicated by the red box in In Photographs and THz images of a metal coin and an IC chip embedded in a debit card are shown in To remove the interference pattern, the origin of the interference patterns should be characterized. Although Ning et al. studied three methods  to eliminate fringe patterns , only onE0, the measured intensity I can be expressed as the sum of the reflected signals from the curved surface E1, planar surface E2 of the Si lens, and sample surface E3 as shown in In our imaging system, the Si lens provides two strong reflective surfaces, namely, the curved and planar surfaces of the Si lens, as Si is a high-refractive-index material in the THz region (n ~ 3.4) . About 3ijr (ijt) is the Fresnel reflection (transmission) coefficient at the i/j-medium interface. Medium 0, 1 and 2 indicate air, Si lens, and sample, respectively. The symbol f is the frequency of the incident THz wave, R is the radius of the Si lens, n1 is the refractive index of the Si lens, c is the speed of light, L is the gap between the planar surface of the Si lens and the sample, and MR1 (MR2) is the number of multiple reflections inside the Si lens (the gap between the planar surface of the Si lens and the sample). During the experiment, E1 and E2 did not change, and the sum of the two terms was defined as FIXE. Then, the Equation (3) is given byE3. This assumption is reasonable because only some of the incoming THz waves are reflected (following the Fresnel coefficient) at the Si lens-air and air-object interfaces. Moreover, the object plane is not perfectly parallel to the planar surface of the Si lens, which leads to an additional loss of detected THz waves. As the signal-to-noise ratio of the imaging system is approximately 200:1, we can easily estimate that the detected power of the THz waves experiencing multiple reflections between the planar surface of the SI lens and the object drops to the noise level. It should be noted, however, that the multiple reflections may need to be considered for highly reflective objects.Here, As mentioned previously, it is difficult to align the object plane perfectly parallel to the planar surface of the Si lens. This means that L varies over the image points when the sample is scanned. When the sample has a flat surface, L changes linearly, which results in sinusoidal fringe patterns over the obtained image, as experimentally shown in the previous section. When the sample has a curved surface, the fringe patterns are more complicated and difficult to describe. When the two images obtained at different axial positions separated by λ/4 are combined, the intensity of the combined image is expressed asEquation (7) shows that the oscillating terms resulting in interference patterns in the image are removed. The above-described interference pattern removal method is applied for THz images of two objects. One has a flat surface, and the other has a complex surface profile. First, THz images of the elements of the group number −2 on the USAF target, which have a flat surface, are obtained as shown in The same process was performed on the image of a dummy finger that had sub-wavelength structures and a complex surface profile, as shown in Note that combining the images obtained at different frequencies can also be utilized for interference pattern removal, as implied in Equation (5). Multispectral images can be easily obtained by changing the THz source to a broadband CW source, such as UTC-PD, as the other optical components are dispersionless in the THz region . This isWe investigated practical issues in THz imaging systems based on a solid immersion lens (SIL). The stability of the system in terms of the longitudinal misalignment of the SIL was experimentally verified. The diffraction-limited sub-wavelength beam size was maintained as long as the Si lens was axially located within the DoF (~13 λ) of the objective lens. The results explicitly show that sub-wavelength resolution can be obtained by simply inserting a Si lens in front of the objects in a typical THz imaging system.Then, we provided a method for minimizing undesirable but inevitable interference patterns embedded in THz images using continuous wave sources. The origin of the fringe patterns was analytically studied, and a method for removing the interference patterns was proposed. By combining two images that were obtained at different axial positions of the sample separated by λ/4, the unwanted interference patterns were significantly reduced, and important information hidden under the interference patterns was revealed, regardless of the surface profile of the sample. Our work proves that the resolution of conventional THz imaging systems can be easily enhanced by simply inserting a SIL in front of the samples with high tolerance in the longitudinal misalignment and provides a method enabling THz imaging for objects having different surface profiles.


This study established a two-stage dynamic game strategy to analyze how the planned quota and price of masks were set and why mask manufacturing firms on the national mask team (NMT) in Taiwan evaded the plan. Plan evasion occurred when the NMT decided to produce less than the quota set by the government, even though they were incentivized and able to produce more. Taiwan’s experience shows that through the collection of masks and the Name-Based Mask Rationing System, the people’s right to procure masks can be guaranteed; however, to promote market transaction efficiency, the government should adopt a lower quota for the collection of masks and allow firms to freely sell them in the market after they complete their plans. The self-interest of the government played a key role in inducing plan evasion. At the beginning of 2020, the COVID-19 pandemic had already reached a global scale. The primary route of transmission of COVID-19 is via small respiratory droplets, and presymptomatic and asymptomatic individuals are able to transmit the virus to others. Karaivanov et al. [The unexpected and sudden pandemic led to the stockpiling and panic-buying of masks by people in Taiwan, causing a face mask shortage; thus, the shortage of masks, soaring prices, and equity of allocation were important issues in the early phase of the COVID-19 pandemic . The govSince January 2020, as the epidemic of this severe and particularly infectious pneumonia has become more severe, confirmed cases have also appeared in Taiwan. The Taiwanese government had concerns that once China controlled the export of masks, Taiwan’s self-produced mask supply would be insufficient. After Taiwan’s medical institutions and people purchased a large number of masks to prevent and control infections that occurred through droplets, there was a shortage of masks.Consequently, in order to ensure a stable supply of masks, the Taiwanese government announced a ban on mask exports on 24 January 2020, also announcing that it would invest more than NT$200 million to build 60 mask production lines to expand its production capacity. In addition, it announced the requisition of masks and implemented the Name-Based Mask Rationing System on February 6. When the requisition of masks was announced, the total production capacity of Taiwan’s mask manufacturers was 1.88 million pieces in 11 h of operation and 4 million pieces within 24 h. The 60 mask production lines set up by the Taiwanese government were under the guidance of the private sector, with each production line capacity based on a daily production of 100,000 masks; thus, the daily production capacity could be increased by 6 million to a total of 10 million per day. These firms were collectively called the National Mask Team (NMT) .After that, on 1 June 2020, as the Taiwanese government confirmed the volume of face masks that it needed to requisition, it finalized its plan to open up mask exports and allowed manufacturers to sell any masks produced beyond the number requisitioned by the government to domestic and overseas buyers .However, a number of mask manufacturing firms in the NMT were found to have privately set up mask production lines to produce and sell masks for profit during the controlled requisition period. For example, in late September 2020, Deer Masks Technology Co. Ltd. was found to have set up unlicensed mask production equipment to produce masks .Although the planned collection allowed the public to buy masks at a lower price, the difference between the official price and the market price also led to the phenomenon of plan evasion by the NMT. An important issue is whether plan evasion ought to exist and why it occurred. A benevolent government planning to expropriate such supplies can benefit the people, but a self-interested government may create a rent-seeking scenario, especially given the shortage of medical supplies during the COVID-19 pandemic period.In this paper, we provide a game analysis to explore why plan evasion might occur when the NMT decides to produce less than the quota established by the government, even though they are incentivized and able to produce more. The self-interest of the government plays a key role in the plan evasion.The organization of the paper is as follows. The literature review provided in The COVID-19 pandemic caused a global shortage of medical masks, leaving many health personnel exposed without appropriate protection. The World Health Organization (WHO) warned of possible shortages of face masks due to rising demand, panic buying, hoarding, and misuse . The govThe WHO also recommended strategies to optimize the availability of personal protective equipment . KirubarIn responding to the COVID-19 pandemic, countries have faced various choices concerning the shortage of masks. One country might intervene in the mask market with a price-ceiling policy only, while another country might take full control of production and distribution of masks. The governments of the world have shared no specific policy on the production and distribution of masks, and there are no related articles available in the public health database.An example of these disparate approaches is the Korean government’s implementation of three Emergency Stabilization Policies, one after another within a month, to stabilize the mask market . The firIn Taiwan, all masks were expropriated by the government, and a Name-Based Mask Rationing System was employed in which people could buy nine masks every fortnight if they were verified via their National Health Insurance card. Moreover, this mask plan safeguarded the purchase of masks and resulted in decreased anxiety in the public over a mask shortage .In order to ensure a stable supply of masks, the Taiwanese government announced a ban on mask exports and invested more than NT$200 million to build 60 mask production lines to expand the production capacity of masks. Since 1 June 2020, the government has shifted from full requisition to fixed-amount requisition of masks, with a total of 8 million pieces per day, based on the production capacity allocation of each firm during the requisition period. The bans on exports and domestic retail sales of masks were lifted. After supplying the requisition quota, firms were free to sell masks domestically and overseas. Tsai et al.  found thThe mask production line of Taiwan’s NMT and the expropriation of private production capacity were critical means of ensuring a stable supply of masks during the COVID-19 period in Taiwan. At the same time, allowing firms to freely sell masks in the market after they had reached the planned quotas reflects the spirit of the gradual dual-track system, in which the command economy and the market economy coexist; this occurred during the economic reform period in mainland China.However, traditionally, liberal economists believe that market shortages should be solved through price mechanisms. Some scholars believe that regulating the market by planning quotas may be a tool of government policies based on self-reliance. In their research on issues related to the setting of planned quotas, Shleifer and Vishny  suggesteAs a well-known step in the transition from a planned economy to a market economy, a dual-track system is usually adopted. In China’s gradual reform, economic agents include farmers, enterprises, and government authorities. Once the economic units reach the planned quota, they earn the right to sell quantities in excess of the quota and even have some freedom in setting the price. According to Koo and Obst , the duaHowever, under the dual-track system, severe plan evasion problems have arisen in state-owned enterprises of the former Soviet Union, Eastern Europe, and China. Plan evasion occurs when state-owned enterprises, faced with production quotas regulated by the government, decide to produce output levels that are lower than the planned quota despite the fact that excess production capacity exists. Jing  indicateTsang and Cheng , expandiThere are, however, unexplained issues in Tsang and Cheng’s paper . First, In order to discuss plan evasion by the NMT, this study established a two-stage dynamic game strategy to analyze how the planned quota and price are set and why the NMT evaded the plan. In the first stage, planners decide on the purchase price and quantity; in the second stage, firms on the NMT determine the production quantity. The concept of rent seeking by government authorities, as suggested by Sheifer and Vishny , and StaIn the game strategy of mask control production, firms on the NMT are like state-owned enterprises under the planned economy of the past. They must reach the planned quota before they can sell the remaining products to the market. This paper discusses plan evasion by the firms on the National Mask Team (NMT) when the government has perfect and imperfect information. We assume that NMT members are price takers and that the planner is rational (self-interest). The objectives are to (i) explore whether rational NMT members will implement plan evasion when the government has complete knowledge of their cost structure and (ii) examine the evasion issue when the government does not possess complete knowledge of their cost structure (imperfect information). Backward induction is used under the premise of Subgame Perfect Nash equilibrium.As mentioned in the previous section, this paper expands on both rent-seeking behavior by government authorities  and the We use a simple model to explore the market equilibrium that allows the NMT’s excess production to be sold in the market after the planned quota is met. Due to the assumption that mask production of all the firms on the NMT is regulated by the planner, firms on the NMT are like state-owned enterprises, and every firm acts as a price-taker as well. Thus, a single firm’s choices are representative of the firms on the NMT. The two-stage sequential game strategy can therefore be modeled by a representative firm, the NMT, that has the same production behavior, and produces the same output as the entire industry.First, firms on the NMT can sell their excess output (production beyond the quota) at market price, i.e., act as price takers. Second, the planned price er. Zhou  indicateGiven these assumptions, the output decision of NMT members can be considered a two-stage sequential game strategy. Initially, by taking into consideration the excess output, the planner will choose a price and output in order to maximize the objective function. Next, NMT members may choose the output level (sum of the planned output and excess output) that maximizes their own profits. As an alternative, NMT members may opt for planned evasion; that is, the profit-maximizing solution is achieved based on the planned price, and the choice depends on which decision makes more profit. We also assume that the planner has perfect information about the NMT members and thus considers their reaction function (relationship between planned quota and excess output) in the process of profit maximization. This is equivalent to finding the subgame equilibrium under perfect information. A solution can be obtained via backward induction.There are two scenarios in which the two-stage sequential game strategy is set. In scenario I, the NMT is expected to fulfill the planned output level. In contrast, the NMT will partially fulfill the plan (plan evasion) in scenario II. We present the formulation in the following cases.Case 1.Optimum excess output when the NMT has achieved the planned quota.Let The first-order and second-order conditions areFrom Equation (2), we can derive the response function of the NMT:Case 2.The optimum output when the NMT partially fulfills the planned quota.As previously stated, when the NMT practices plan evasion, it pays to choose the optimum output Likewise, from (6), we can derive the response function of the NMT:Case 3.The optimum planned output and price of the planner when the NMT has achieved the planned quota.To ensure that the NMT can fulfill the planned quota, the planned output should comply with the incentive compatibility constraint; that is, By invoking the Kuhn–Tucker condition, the optimum planned price and output areThe profit of the NMT and the target of the planner can be obtained:We can now use Accordingly, we have the following lemma.Lemma 1.The planned output and price are independent of the public interest if the planner anticipates that the NMT meets the plan.In the theoretical framework of this article, the objective function of the central planner includes his or her self-interest and the profit of the NMT. The self-interest component is mainly the rent obtained by the difference between the planned price and the market price; this component may be due to the political capital generated by the power to distribute masks. On the other hand, the central planner must also take into account the profits obtained by the NMT. The main reason is that the profits of the NMT will eventually enter the private economy as wages, interest, or profits.When the planner expects that the NMT will complete the plan as scheduled, the planned price and planned output are independent of the degree of public interest, mainly because the output of the NMT will be determined by the condition of marginal revenue being equal to the marginal cost. In a competitive market, due to the constant marginal revenue, there must be a level of output at which the price  equals marginal cost. At this time, the planned price and output set by the planner just maximize its rent and are independent of the degree of public interest.Case 4.The Optimum Planned Output and Price Set by the Planner When Plan Evasion Occurs.To guarantee the output level when plan evasion occurs and to assure that the plan meets the incentive compatibility condition of the NMT  in Finally, the optimum solution of the endogenous variables, including the planned output and price, correlates positively with Accordingly, we have the following lemma.Lemma 2.The planned output and price increase with the public interest if the planner anticipates that the NMT will implement plan evasion.When the planner expects that the NMT will evade the plan because its masks cannot be sold beyond what is stipulated in the plan, they can only be purchased by the state at the planned price. The planner will set a higher planned output and planned price to increase the profit of the NMT if the planner pays more attention to the welfare of the NMT and vice versa. When the planner ascribes equal weight to its own interests and the profit of the NMT, then its planned quota will be set at the competitive output, and when the planned price is lower than the competitive price, the NMT will inevitably respond with low-level production.The above analysis shows that, with perfect information, the production behavior of the NMT is controlled by the planner. Given that the planner (i) designs the plan, (ii) considers the optimum response function of the NMT, (iii) complies with the incentive compatibility condition, and (iv) makes adjustments via the planned quota and price, the NMT will choose either excess production or plan evasion as the planner has anticipated.Will the NMT opt for excess production or plan evasion? The answer is readily available: when the planner has a stronger incentive to benefit him- or herself  for the analysis. Nature first decides the cost structure of the NMT, which the planner does not know. This imperfect information game theory translates into a game strategy with complete but imperfect information. Afterwards, we can analyze this model with the traditional method of tackling uncertainty. Given that the planner merely knows the probability distribution, he or she can only find the solution in terms of a maximum expected value. That is to say, the planner will consider the excess production of the NMT and fix a planned price and quota in order to maximize the expected value. Moreover, given the order of the plan from the planner, the NMT is expected to choose an optimum output in order to maximize the excess profit of the plan.As indicated in the previous section, the goal of the NMT is to maximize its profit, Case 5.Optimum excess output when the NMT has achieved the planned quota.We start with the case in which the NMT fulfills the plan with the following objective function. Given this, the NMT’s profit maximization problem isThe first-order and second-order conditions for Equation (23) yieldFrom Equation (24), we can derive the response function of the NMT:Case 6.The optimum output when the NMT partially fulfills the planned quota.On the other hand, when the NMT opts for plan evasion, the objective function can be defined asAgain, the first-order and second-order conditions lead toLikewise, from Equation (28), we can derive the response function of the NMT:When a planner designs the plan, he or she will have to take into account the following scenarios:(1) Both firms with high- and low-cost structures fulfill the plan; (2) the firm with the low-cost structure fulfills the plan, while the firm with the high-cost structure evades the plan; (3) both types of firms evade the plan; or (4) the firm with the high-cost structure fulfills the plan, while the firm with the low-cost structure evades the plan.Given a market price, planned quota, and planned price, the firm with a low cost will be comparatively more profitable. As such, scenario (4) is not feasible. In other words, the planner will determine the planned quota according to scenarios (1), (2), and (3). Given the types of cost structure and the corresponding incentive compatibility condition, the NMT’s choice to fulfill the plan or practice plan evasion depends on the manipulation of the central planner.The maximum expected returns from scenarios (1), (2), and (3) for the planner and the NMT are given in Similarly, if a planner hopes that the high-cost firm exercises plan evasion and the low-cost firm fulfills the plan, he or she needs to consider two incentive compatibility conditions. One is for the low-cost firm to have excess production, and the other is for the high-cost firm to opt for plan evasion.Moreover, if the planner hopes that both firms exercise plan evasion, he or she will consider only the constraint on the low-cost firm. If the low-cost firm is reluctant to carry out the plan, the high-cost firm will definitely not fulfill it. In such a situation, the incentive compatibility condition is reduced to the constraint only on the low-cost firm.What intrigues us most here is how the planner designs a plan. When the payoff in scenario (1) is greater than that in scenario (2) or (3), the planner will design a plan in which both types of firms fulfill the target and have excess production. When the payoff in scenario (2) is greater than that in scenario (1) or (3), the planner will design a plan in which the high-cost firm exercises plan evasion and, at the same time, the low-cost firm fulfills the target. Likewise, when the payoff in scenario (3) is greater than that in scenario (1) or (2), the planner will design a plan in which both firms exercise plan evasion.According to The reverse is true for Second, for Likewise, similar conditions hold for Third, in the case of Again, similar conditions hold for As is evident from (31), (32), and (33), the decisions of the planner are affected by the probability of knowing cost structures  both firms with high- and low-cost structures fulfill the plan; or (2) the firm with the low-cost structure fulfills the plan, while the firm with the high-cost structure evades it.On the one hand, when employing a plan that results in both high- and low-cost firms fulfilling it, the planner sets a lower planned quota to stimulate both high-cost and low-cost firms to meet the planned quota and incorporate any excess output. At this time, planners receive a low allocation of masks, but they can meet the needs of the public interest through the excess output of firms. On the other hand, when the planner imposes a plan that causes the low-cost firms to fulfill it while high-cost firms evade it, the planned quota is relatively high. The low-cost firms still choose to complete the planned quota and sell the excess output to the market; however, the high-cost firms will not complete the planned quota due to the high production cost of the excess output, so they will have low-level production and be unwilling to overproduce.According to the above analysis, to minimize the expected loss and enhance welfare, a planner is more likely to impose a plan in which both firms with high- and low-cost structures fulfill the plan when (i) the probability of the high-cost firm  if the rational planner has self-interest and perfect information, the NMT will not exercise plan evasion, and (ii) in the situation of imperfect information, with a low probability attributed to the high-cost firm  issued a sweeping order requiring the use of face masks on nearly all forms of public transportation, as the country continued to report thousands of daily COVID-19 deaths . Owing tOn the one hand, Taiwan’s experience shows that through the collection of masks and the Name-Based Mask Rationing System, the people’s right to procure masks can be guaranteed, and they have an equal probability of acquisition; however, plan evasion may be caused by plans with inappropriate quotas. Therefore, to promote market transaction efficiency, the government should adopt a lower quota for the collection of masks and allow manufacturers to freely sell them in the market after completing their plans. On the other hand, incorporating a risk-based approach into the collection of masks could be a more effective method to ensure that they are provided to people at a high or moderate risk of infection. Without effective public communication, a universal face mask wearing policy could result in societal panic and subsequently increase the nationwide and worldwide demand for face masks. These increased demands could cause a face mask shortage for healthcare workers and reduce the effectiveness of outbreak control in affected regions, eventually leading to a pandemic .The limitations of this article are as follows: First, only plan evasion by firms on the NMT in a competitive market is discussed, but the actual market structure might be oligopolistic; second, the planner’s degree of concern for the public interest is set to be less than that of self-interest, but in fact, the planner might be more concerned about the public interest than self-interest. These model settings could lead to changes in the conclusions of this research.Further study of the NMT’s plan evasion can be expanded by (i) using screening models to discuss the NMT’s plan evasion under imperfect information; (ii) including pricing power under an imperfect competitive market; and (iii) incorporating the demand uncertainty into this model in order to discuss the NMT’s plan evasion and planner’s optimum quota, among other factors.


The shoulder joint is the most common joint to undergo dislocation, with the anterior subtype being the most common. The most accepted definition of chronic dislocation is a shoulder joint that has remained dislocated for a minimum of three weeks. Due to rare presentation, there is a lack of consensus among surgeons regarding the optimal management option of chronic shoulder dislocation. The goal of this prospective study was to assess the efficacy of open reduction with Latarjet procedure in the management of chronic unreduced shoulder dislocation. A total of seven patients were included in this study. Five patients were males and two were females. The study was conducted in a single tertiary care centre between July 2015 and May 2018. All patients were managed by open reduction with the Latarjet procedure. The capsulolabral structures were repaired in all the cases. The post-operative functional outcome was assessed by shoulder range, Rowe score, and the University of California, Los Angeles (UCLA) score at regular intervals for a period of one year. There was a significant improvement in terms of pain relief and functional status of the patients. The patients were satisfied as they could do their daily routine activities without pain at a one-year follow-up. Early post-operative rehabilitation and physiotherapy are key to improving the functional range. The shoulder joint is the most common joint to undergo dislocation, with the anterior subtype being the most common . Most ofThe prospective study on seven patients was conducted at the department of orthopaedics of a tertiary care hospital with prior approval for the same from the Departmental Review Board and Institutional Ethics Committee before the initiation of the study . The study includes all unilateral cases of chronic anterior dislocation of the shoulder managed by open reduction by the Latarjet procedure. Exclusion criteria were as follows: (i) acute shoulder dislocations of less than three weeks duration; (ii) recurrent anterior dislocation of the shoulder; (iii) chronic anterior dislocation of the shoulder associated with neuropathic arthropathy; (iv) congenital anterior dislocation of the shoulder; (v) patients with medical comorbidities who were surgically unfit; and (vi) bilateral shoulder dislocation.This was a single tertiary care centre, prospective study, which included all cases of chronic anterior dislocation of the shoulder between July 2015 and May 2018. Seven patients with chronic anterior shoulder dislocations  were included in the study  and two females 29%). The mean age of the patients was 47.1 years (range: 17-62 years). The duration of the dislocations ranged from 45 to 124 days (mean = 75.5). The patients were routinely followed up postoperatively at three weeks, six weeks, three months, six months, and 12 months for clinical evaluation and radiographs (Table 9%. The mThe shoulder joint is the most vulnerable and thus the most common joint to undergo dislocation. Shoulder dislocation can occur in any direction, anterior being the most common. Various authors have defined chronic dislocations in different ways. Few authors suggested that any dislocation that has not been reduced in a period of 24 hours should be considered chronic dislocation . Goga deBabalola et al. managed nine cases of chronic anterior shoulder dislocation by open reduction and fixation with Kirschner wires in five patients and non-operative management in four patients . They coIn our study, we managed all patients by open reduction with the Latarjet procedure. The capsulolabral structures were repaired in all cases. Two patients complained of numbness over the lateral aspect of the upper arm, which gradually resolved by the six weeks follow up. The outcome in terms of VAS score, UCLA score, Rowe score, and the functional status of the shoulder joint was significantly better during the 12-month post-operative period. All patients were satisfied with the outcome in terms of pain relief and functional improvement of the shoulder joint.There are a few limitations of our study. First, there was no control group in our study for comparison. Second, considering the rarity of this condition, the sample size was small to comment on the efficacy of the Latarjet procedure in the management of chronic shoulder dislocation. Third, the follow-up period of this study was short, i.e., around 14 months. Fourth, a CT scan needs to be done to quantify bone loss.Open reduction with Latarjet procedure is a highly successful procedure in the management of chronic anterior shoulder dislocation. The procedure decreases pain and improves the functional status of the patient. The associated musculoskeletal injury needs to be addressed properly for improving the outcome. Due to rare presentation, there is a lack of consensus among surgeons regarding the optimal management option of chronic shoulder dislocation. There is a need for a study with higher sample size and long-term follow up. Early post-operative rehabilitation and physiotherapy are key to improving the functional range. In conclusion, although it is under debate regarding the optimal management option of an old unreduced shoulder dislocation, our study advocates that open reduction with Latarjet procedure offers a decrease in pain and satisfies the patient with the improvement in joint movement, which enables them to perform their daily activities.