43 research outputs found
Geometry-aware stationary subspace analysis
No full textInternational audienceIn many real-world applications data exhibits non-stationarity, i.e., its distribution changes over time. One approach to handling non-stationarity is to remove or minimize it before attempting to analyze the data. In the context of brain computer interface (BCI) data analysis this is sometimes achieved using stationary subspace analysis (SSA). The classic SSA method finds a matrix that projects the data onto a stationary subspace by optimizing a cost function based on a matrix divergence. In this work we present an alternative method for SSA based on a symmetrized version of this matrix divergence. We show that this frames the problem in terms of distances between symmetric positive definite (SPD) matrices, suggesting a geometric interpretation of the problem. Stemming from this geometric viewpoint, we introduce and analyze a method which utilizes the geometry of the SPD matrix manifold and the invariance properties of its metrics. Most notably we show that these invariances alleviate the need to whiten the input matrices, a common step in many SSA methods which often introduces error. We demonstrate the usefulness of our technique in experiments on both synthetic and real-world data
The brain mechanisms underlying walking in complex situations in healthy older adults and persons with Parkinson's disease
No full textIntroduction: The ability to walk safely and independently is a fundamental component of daily living activities. Walking while dual tasking and obstacle negotiation are two tasks that have been used to investigate walking in complex situations. Deficits in cognitive domains and sensory-motor processes associated with aging and neurodegenration impair the ability to successfully assess the environment and react to it. These changes in the ability to walk are modulated via neural circuits. However, the actual neural circuits of the brain involved in the control of locomotion in different challenging situations are still poorly understood. Methods: Two groups of subjects; 20 healthy older adults (mean age 69.7±1.3 yrs, 50% females) and 47 persons with PD (mean age 71.7±1.1 yrs, 32% females) were studied. The protocol included real and imagined walking while negotiating obstacles and dual tasking. Walking conditions were performed while being monitored with fNIRS and imagined walking were assessed in the MR scanner. A repeated measures design (condition x group) was conducted with two levels; within group and between groups. Results: Significant differences in brain activation were observed in the fMRI and fNIRS. Between groups comparison showed that persons with PD had a significantly higher activation in frontal, parietal, occipital, and cerebellum regions during usual walking compared to healthy older adults (p<0.048). Comparison between the walking tasks within each group revealed (1) increased activation during walking while negotiating obstacles in both groups (p<0.023) and (2) increased activation during walking while dual tasking only in healthy older adults (p<0.035). Correlations between brain activation and performance in motor-cognitive tests were found in both groups however, healthy older adults presented inverse correlation and persons with PD positive correlation. Conclusions: These findings indicate that subjects with PD activate larger brain areas than healthy older adults even during usual walking. Perhaps, this increased activation is a compensatory strategy to enhance performance. The increased activation already during usual walking task may limit the ability to increase activation or recruit additional brain areas during the more complex walking tasks and may contribute to the high prevalence of falls and the dual tasking difficulty in persons with PD.Ph.D.Includes bibliographical referencesby Inbal Maida
Determination of elevated eosinophil to lymphocyte ratio, eosinophil to neutrophil ratio, eosinophil to monocyte ratio and its association with severe vitiligo: A retrospective cohort study.
No full textBackgroundHematological markers such as eosinophil-to-lymphocyte (ELR), eosinophil-to-neutrophil (ENR), and eosinophil-to-monocyte (EMR) ratios may be used in the assessment of skin diseases. However, the relationship with vitiligo remains unclear.ObjectivesWe investigated ELR, ENR, and EMR in vitiligo patients and the association with severe vitiligo.MethodsThis study included patients of all ages diagnosed with vitiligo between 2005-2020. ELR, EMR, and ENR were calculated from complete blood counts within 30 days of the first recorded vitiligo diagnosis and 12-18 months before the vitiligo diagnosis. We evaluated the associations between ELR, ENR, and EMR and vitiligo.Results9,826 vitiligo patients (8,398 adults and 1,428 children) and 8,951 age and sex-matched controls were included in this study. We found that ELR, EMR, and ENR were higher in children than in adults. Patients with vitiligo had higher ENR and EMR than their matched controls. Patients with severe vitiligo had higher ELR, ENR, and EMR compared to patients with mild vitiligo. Patients with increased ENR and EMR 12-18 months before the vitiligo diagnosis had a higher chance of having severe vitiligo (ENR: OR = 7.40, pConclusionELR, ENR, and EMR may be used in the assessment and prognosis of vitiligo, especially in severe cases
From First-Year Dreams to Sixth-Year Realities: A Repeat Cross-Sectional Study of Medical Students’ Specialty Preferences
No full textMedical students often begin their studies with preconceived notions about specialties, which may evolve as they gain clinical experience. This study aimed to assess changes in specialty preferences over six years of medical training and to compare two cohorts of first-year students. A repeat cross-sectional design was used, analyzing survey data from the 2019 class during preclinical (first–second year) and clinical (sixth year) stages, and from the 2024 first-year cohort. A total of 367 students participated. Comparing preclinical and clinical students revealed a significant increase in interest in ophthalmology (2.9% vs. 11%, p = 0.012), along with non-significant upward trends in obstetrics and gynecology and family medicine. Declines were observed in psychiatry, oncology, neurosurgery, and surgery. The 2024 cohort included a higher proportion of students with a prior medical background compared with the 2019 cohort (43% vs. 23%, p = 0.002), but no other demographic or specialty preference differences were identified. These findings suggest that specialty preferences among medical students may shift during clinical training, while initial preferences appear relatively consistent across cohorts. Understanding how medical education influences career development may guide curricular strategies to balance specialty distribution and address workforce needs
Revisiting Qusayr Amra: A New Perspective on Female Imagery
No full textThis essay argues that female representations at Qusayr Amra reflect a deliberate adaptation of pre-Islamic artistic traditions, expressing evolving Umayyad ideas of beauty, gender, and hierarchy. By analyzing the interplay between visual imagery and written texts, including the Qur’an, it reevaluates the significance of female figures and the representational choices made in 8th-century Umayyad palaces in Bilad al-Sham. Drawing on scholars such as Garth Fowden and Nadia Ali, and informed by contemporary gender studies, this essay foregrounds how artistic choices regarding female imagery negotiate social ideals of belief, gender, and power. The analysis begins by examining the development of figurative imagery in early Islam and its cultural context. It then offers a close reading of a key fresco challenging assumptions about modesty and figural representation. Through comparative analysis with another Umayyad site, this study highlights the complexities and meanings of female depictions, revealing diverse interpretations across contexts. While Patron Walid II was not the sole author of these choices, his patronage was crucial in enabling a bold engagement with Islamic visual culture. In doing so, this essay offers new insights into the complexities of early Islamic visual culture and its negotiation of social values
Hematological ratios as an indicator of severity in alopecia areata: A retrospective nationwide study
No full text
STROBE statement—checklist of items that should be included in reports of observational studies.
No full textSTROBE statement—checklist of items that should be included in reports of observational studies.</p
Youden indexes for severe vitiligo.
No full textBackgroundHematological markers such as eosinophil-to-lymphocyte (ELR), eosinophil-to-neutrophil (ENR), and eosinophil-to-monocyte (EMR) ratios may be used in the assessment of skin diseases. However, the relationship with vitiligo remains unclear.ObjectivesWe investigated ELR, ENR, and EMR in vitiligo patients and the association with severe vitiligo.MethodsThis study included patients of all ages diagnosed with vitiligo between 2005–2020. ELR, EMR, and ENR were calculated from complete blood counts within 30 days of the first recorded vitiligo diagnosis and 12–18 months before the vitiligo diagnosis. We evaluated the associations between ELR, ENR, and EMR and vitiligo.Results9,826 vitiligo patients (8,398 adults and 1,428 children) and 8,951 age and sex-matched controls were included in this study. We found that ELR, EMR, and ENR were higher in children than in adults. Patients with vitiligo had higher ENR and EMR than their matched controls. Patients with severe vitiligo had higher ELR, ENR, and EMR compared to patients with mild vitiligo. Patients with increased ENR and EMR 12–18 months before the vitiligo diagnosis had a higher chance of having severe vitiligo (ENR: OR = 7.40, pConclusionELR, ENR, and EMR may be used in the assessment and prognosis of vitiligo, especially in severe cases.</div
Laboratory characteristics of patients with vitiligo, stratified by severity group.
No full textLaboratory characteristics of patients with vitiligo, stratified by severity group.</p
