High temperature epsilon-near-zero and epsilon-near-pole metamaterial emitters for thermophotovoltaics

We propose a method for engineering thermally excited far field electromagnetic radiation using epsilon-near-zero metamaterials and introduce a new class of artificial media: epsilon-near-pole metamaterials. We also introduce the concept of high temperature plasmonics as conventional metamaterial building blocks have relatively poor thermal stability. Using our approach, the angular nature, spectral position, and width of the thermal emission and optical absorption can be finely tuned for a variety of applications. In particular, we show that these metamaterial emitters near 1500 K can be used as part of thermophotovoltaic devices to surpass the full concentration Shockley-Queisser limit of 41%. Our work paves the way for high temperature thermal engineering applications of metamaterials.Comment: 15 pages, 8 figure

Statistical shape analysis and principal component analysis of the clavicle

\u22The chief use of the clavicle is to hold the shoulder blade at the proper distance from the breastbone, since motion of the shoulder would be hindered if the two came close together, as seen in four-footed animals that can use their forefeet only for walking, and not in the way that men need their hands.\u22 - Therselben, 1790 Although anthropometric work on the clavicle by Broca dates as far back as 1869 according to Voisin1, the role of the clavicle has been described more than 200 years ago by Therselben. While one study stated that the clavicle is the most frequently fractured bone of the human skeleton2, data collected in Malmo, Sweden between 1952 and 1987 showed that fractures of the clavicle only accounted for 4% of all fractures, but that this represented 35% of all fractures in the shoulder region3. Other studies have shown similar results, estimating that clavicular fractures account for 5 to 10% of all fractures4,5, and 44% of all injuries to the shoulder girdle6. According to Wheeless\u27 Online Textbook of Orthopaedics, fractures to the middle third are the most common in adults and children, accounting for account for 80% while fractures to the lateral third are seen in 15% with the remaining 5% affecting the medial third. Numerous studies have verified this, statingthat 80% of clavicular fractures occur in the middle third, 10 to 18% in the lateral third and 2 to 10% in the medial third 7,8,9,10,11. This can be explained by a number of facts. Firstly, that the narrowest part of the clavicle is at the meeting point of the sternal convexity and the acromial concavity, which is the location of the majority of clavicle fractures2. Second of all, there is a significant decrease in bone density at the transition from middle to lateral thirds of the clavicle, explaining the increased frequency of fractures occurring in the middle and lateral thirds2. It has also been previously shown that the mid-portion of the clavicle is the thinnest and narrowest part of the bone and represents a transitional region of the bone, both in curvature and cross-sectional anatomy, making it a mechanically weak area that is most likely to fracture12. In terms of location, the sternoclavicular and acromioclavicular joints hold the clavicle in its anatomical position with the latter having been described as a \u27keystone\u27 link between the scapula and clavicle13. Its integrity plays an important role in the movement of the shoulder girdle. The construct of the ACJ makes it a very strong joint able to tolerate a significant amount of force before disruption. This explains that in comparison to clavicular fractures, injuries to the ACJ account for approximately only 12% of those to the shoulder girdle seen in clinical practice14. Much higher incidences are seen in contact sports. In rugby, ACJ injuries have been shown to account for 32% of shoulder injuries15 and in American football they are the most common injury to the shoulder16. Even in non-contact sports such as recreational skiing, about 20% of injuries to the shoulder girdle involve the ACJ17. With the majority of injuries to the ACJ seen in young males, the same applies to fractures of the clavicle18. The main aim in treating fractures of the clavicle is to provide comfort and pain relief. Management options for both ACJ injuries as well as fractures of the clavicle vary widely, spanning from conservative treatment to fixation requiring surgical intervention with the latter including a variety of options from minimally invasive techniques19 to the application of a fixation plate. Whenever a fixation implant is to be selected, several factors drive the decision. The fit on bone of any fixation plate has a direct impact on the strength of the construct. However, current clavicular implants overlook the variations in geometry of the bone. In 2007, a paper describing the anatomy of the clavicle stated that gender specific anatomical features should be taken into consideration when performing intramedullary fixation of the clavicle2. While the length, diameters and curvature of the clavicles measured were based on 196 embalmed specimens, cortical bone thickness and the medullary canal diameter were determined using only 10 fresh specimens. In a more recent article, it has been reported that cortical bone thickness and bone shape of the clavicle have large effects on bone responses until failure and on fracture location20. This study emphasized the need for geometrical personalization of clavicle models in order to consider various age, gender and shape discrepancies. However, the radiological aspect of this study was based only on six clavicles with the biomechanical testing based on 18 clavicles from nine subjects with a mean age of 78. From a clinical standpoint, a larger number and much younger population should be studied, considering that fractures to the clavicle are most commonly seen in the twenties although comminuted fractures may be more common in the third and forth decades. The relationship between clavicular length restoration post-fracture and functional outcome remains controversial. Some studies have concluded no observable reduction in shoulder function 21,22,23, while others have stressed the importance of restoration of clavicular length post-fracture 24,25. Previous literature has also stated that up to 30% of patients treated non-operatively develop unsatisfactory outcomes clinically, radiologically, and subjectively because of bony shortening, malunion, poor alignment or deforrnity 24,25,26,27. In another study of outcome after closed treatment of the fractured clavicle, the majority of patients were not satisfied with the cosmetic deformity and 40% complained of impaired function28. Although most fractures of the clavicle have a good prognosis and can be managed conservatively, the role of surgical intervention and its importance must not be forgotten. In the literature, some studies focused on clavicle tests 20,29,30,31, while others focused on geometry 2,12,20,32. However, these studies had very small sample sizes as previously stated. As plate and intramedullary fixation are accepted and widely used methods of treatment, a study analyzing the shape and looking into the necessity for modifying modern implants in order to optimize fixation based on personalized bony geometry has much clinical relevance with regard to the management of clavicular fractures. One recent study set out to characterize variations in clavicular anatomy and determine the clinical applicability of an anatomic precontoured clavicular plate designed for fracture fixation33. However, the authors themselves stated that their main limitation was that it was a two-dimensional analysis of plate fit rather than a three-dimensional analysis. By noting the shortcomings of the abovementioned studies, this thesis focuses on the anatomy of the clavicle and the analysis and application of it to the design of currently available clavicle fixation plates in both a systematic and structured manner

Laparoscopic Nissen fundoplication post-oesophageal stenting: an unusual case.

Laparoscopic Nissen fundoplication post-oesophageal stenting is uncommon and yet to be reported. We report the case of a 57-year-old palliative lady who underwent surgery for symptomatic relief of severe gastrooesophageal reflux post-oesophageal stenting. Surgery was carried out successfully with no complications. On the evening post-surgery she was able to lie supine for the first time in months without symptoms of reflux. In conclusion, surgery is still valuable and may play an important role, even in a palliative setting

An application of principal component analysis to the clavicle and clavicle fixation devices

BACKGROUND: Principal component analysis (PCA) enables the building of statistical shape models of bones and joints. This has been used in conjunction with computer assisted surgery in the past. However, PCA of the clavicle has not been performed. Using PCA, we present a novel method that examines the major modes of size and three-dimensional shape variation in male and female clavicles and suggests a method of grouping the clavicle into size and shape categories. MATERIALS AND METHODS: Twenty-one high-resolution computerized tomography scans of the clavicle were reconstructed and analyzed using a specifically developed statistical software package. After performing statistical shape analysis, PCA was applied to study the factors that account for anatomical variation. RESULTS: The first principal component representing size accounted for 70.5 percent of anatomical variation. The addition of a further three principal components accounted for almost 87 percent. Using statistical shape analysis, clavicles in males have a greater lateral depth and are longer, wider and thicker than in females. However, the sternal angle in females is larger than in males. PCA confirmed these differences between genders but also noted that men exhibit greater variance and classified clavicles into five morphological groups. DISCUSSION AND CONCLUSIONS: This unique approach is the first that standardizes a clavicular orientation. It provides information that is useful to both, the biomedical engineer and clinician. Other applications include implant design with regard to modifying current or designing future clavicle fixation devices. Our findings support the need for further development of clavicle fixation devices and the questioning of whether gender-specific devices are necessary

Subacute sclerosing panencephalitis: case based review

Subacute sclerosing panencephalitis (SSPE) is a chronic debilitating condition that occurs in children affected with measles. SSPE is broadly distinguished as typical SSPE, the more rampant form, occurring over a period of years following primary measles infection, while the atypical has a more rapidly progressive course over weeks to months. SSPE can present with cognitive, epileptic, autonomic, pyramidal and ophthalmologic manifestations with scholastic decline being the primary feature. The management of SSPE focuses on improvement of quality of life and prolongation of survival which can be achieved with the use of supportive care modalities and immunomodulators respectively. This is a comprehensive review which discusses several parameters of SSPE such as epidemiology, pathophysiology, clinical presentations, and detailed management protocol for this condition. As part of this review, we also discuss a case of rapidly progressive, fulminant and atypical SSPE in a five-year-old male presenting clinically with myoclonic jerks of lower extremities

Investigation of three-dimensional shock wave/turbulent-boundary-layer interaction initiated by a single fin

Three-dimensional shock wave/turbulent-boundary-layer interaction of a hypersonic flow passing a single fin mounted on a flat plate at a Mach number of five and unit Reynolds number 3.7×10^7 was conducted by a large-eddy simulation approach. The performed large-eddy simulation has demonstrated good agreement with experimental data in terms of mean flowfield structures, surface pressure distribution, and surface flow pattern. Furthermore, the shock wave system, flow separation structure, and turbulence characteristics were all investigated by analyzing the obtained large-eddy simulation dataset. It was found that, for this kind of three-dimensional shock wave/turbulent-boundary-layer interaction problem, the flow characteristics in different regions have been dominated by respective wall turbulence, free shear layer turbulence, and corner vortex motions in different regions. In the reverse flow region, near-wall quasi-streamwise streaky structures were observed just beneath the main separation vortex, indicating that the transition of the pathway of the separation flow to turbulence may occur within a short distance from the reattachment location. The obtained large-eddy simulation results have provided a clear and direct evidence of the primary reverse flow and the secondary separation flow being essentially turbulent

Exploring the influence of cultural orientations on assessment of communication behaviours during patient-practitioner interactions

Background Research has shown that patients’ and practitioners’ cultural orientations affect communication behaviors and interpretations in cross-cultural patient-practitioner interactions. Little is known about the effect of cultural orientations on assessment of communication behaviors in cross-cultural educational settings. The purpose of this study is to explore cultural orientation as a potential source of assessor idiosyncrasy or between-assessor variability in assessment of communication skills. More specifically, we explored if and how (expert) assessors’ valuing of communication behaviours aligned with their cultural orientations (power-distance, masculinity-femininity, uncertainty avoidance, and individualism-collectivism). Methods Twenty-five pharmacist-assessors watched 3 videotaped scenarios (patient-pharmacist interactions) and ranked each on a 5-point global rating scale. Videotaped scenarios demonstrated combinations of well-portrayed and borderline examples of instrumental and affective communication behaviours. We used stimulated recall and verbal protocol analysis to investigate assessors’ interpretations and evaluations of communication behaviours. Uttered assessments of communication behaviours were coded as instrumental (task-oriented) or affective (socioemotional) and either positive or negative. Cultural orientations were measured using the Individual Cultural Values Scale. Correlations between cultural orientations and global scores, and frequencies of positive, negative, and total utterances of instrumental and affective behaviours were determined. Results Correlations were found to be scenario specific. In videos with poor or good performance, no differences were found across cultural orientations. When borderline performance was demonstrated, high power-distance and masculinity were significantly associated with higher global ratings (r = .445, and .537 respectively, p < 0.05) as well as with fewer negative utterances regarding instrumental (task focused) behaviours (r = −.533 and − .529, respectively). Higher masculinity scores were furthermore associated with positive utterances of affective (socioemotional) behaviours (r = .441). Conclusions Our findings thus confirm cultural orientation as a source of assessor idiosyncrasy and meaningful variations in interpretation of communication behaviours. Interestingly, expert assessors generally agreed on scenarios of good or poor performances but borderline performance was influenced by cultural orientation. Contrary to current practices of assessor and assessment instrument standardization, findings support the use of multiple assessors for patient-practitioner interactions and development of qualitative assessment tools to capture these varying, yet valid, interpretations of performanceScopu