Second fundamental form of the Prym map in the ramified case

In this paper we study the second fundamental form of the Prym map $P_{g,r}: R_{g,r} \rightarrow {\mathcal A}^{\delta}_{g-1+r}$ in the ramified case $r>0$. We give an expression of it in terms of the second fundamental form of the Torelli map of the covering curves. We use this expression to give an upper bound for the dimension of a germ of a totally geodesic submanifold, and hence of a Shimura subvariety of ${\mathcal A}^{\delta}_{g-1+r}$, contained in the Prym locus.Comment: To appear in Galois Covers, Grothendieck-Teichmueller Theory and Dessins d'Enfants - Interactions between Geometry, Topology, Number Theory and Algebra. Springer Proceedings in Mathematics & Statistics. arXiv admin note: text overlap with arXiv:1711.0342

Population-Based Utility of van Herick Grading for Angle-Closure Detection

Primary angle-closure glaucoma accounts for half of glaucoma-related blindness worldwide with a disproportionate burden of disease found in Asian populations. The clinical reference standard for diagnosis of angle closure is gonioscopy, but van Herick (VH) grading of limbal anterior chamber depth (LACD) has been used as a screening tool, with varying sensitivities and specificities on classifying gonioscopically occludable angles reported in Chinese and other East Asian populations. A cutoff of VH grade ≤1 (modified grade ≤15%) has been found to have sensitivities ranging from 19% to 84% and specificities from 86% to 100%, whereas a higher cutoff VH grade ≤2 (modified grade ≤25%) has had sensitivities ranging from 54% to 99% and specificities from 65% to 96%. However, the efficacy of using the VH test as a screening tool in community-based screening programs to identify gonioscopically occludable angle has not been investigated. The purpose of this study was to determine the sensitivity and specificity of modified VH grading of LACD in detecting gonioscopically defined primary angle-closure suspects (PACS) among subjects screened for participation in the Zhongshan Angle Closure Prevention (ZAP) Trial in southern China

Anatomical Changes and Predictors of Angle Widening After Laser Peripheral Iridotomy: The Zhongshan Angle Closure Prevention Trial

PURPOSE: To assess anatomical changes after laser peripheral iridotomy (LPI) and predictors of angle widening based on anterior segment OCT (AS-OCT) and angle opening based on gonioscopy in mainland Chinese primary angle closure suspects (PACS). DESIGN: Prospective observational study. PARTICIPANTS: 454 subjects aged 50 to 70 years with PACS. METHODS: Subjects received clinical examinations including gonioscopy and AS-OCT imaging at baseline and 2 weeks after LPI as part of the Zhongshan Angle Closure Prevention (ZAP) Trial. PACS was defined as inability to visualize pigmented trabecular meshwork in two or more quadrants on static gonioscopy. LPI was performed on one eye per subject in a superior (between 11 to 1 o'clock) or temporal or nasal (at or below 10:30 or 1:30 o'clock) location. Biometric parameters in horizontal and vertical AS-OCT scans were measured and averaged. Multivariable linear and logistic regression modeling were performed to determine predictors of angle widening, defined as change in continuous measurements of mean angle opening distance (AOD750), poor angle widening, defined as the lowest quintile of change in mean AOD750, and poor angle opening, defined as residual PACS after LPI based on gonioscopy. MAIN OUTCOME MEASURES: Anatomical changes and predictors of angle widening and opening after LPI. RESULTS: 454 subjects were included in the analysis. 219 received superior LPIs and 235 received temporal or nasal LPIs. There were significant changes among most biometric parameters (p<0.006) after LPI, including greater AOD750 (p<0.001). 120 eyes (26.4%) had residual PACS after LPI. In multivariable regression analysis, several baseline parameters, including superior LPI location (p=0.004), smaller AOD750 (p<0.001), and greater iris curvature (p<0.001), were predictive of greater angle widening. Temporal or nasal LPI locations (OR=2.60, p<0.0001) and greater baseline AOD750 (OR=2.58, 0.1 mm increment, p<0.001) were most predictive of poor angle widening based on AS-OCT. Smaller mean gonioscopy grade (OR=0.34, 1 grade increment) was most predictive of poor angle opening based on gonioscopy. CONCLUSIONS: Superior LPI location results in significantly greater angle widening based on AS-OCT compared to temporal or nasal locations in a Chinese population with PACS. This supports consideration of superior LPI locations to optimize anatomical changes after LPI

New Massive Gravity Domain Walls

The properties of the asymptotic $AdS_3$ space-times representing flat domain walls (DW's) solutions of the New Massive 3D Gravity with scalar matter are studied. Our analysis is based on $I^{st}$ order BPS-like equations involving an appropriate superpotential. The Brown-York boundary stress-tensor is used for the calculation of DW's tensions as well as of the $CFT_2$'s central charges. The holographic renormalization group flows and the phase transitions in specific deformed $CFT_2$ dual to 3D massive gravity model with quadratic superpotential are discussed.Comment: 12 pages,v2-misprints corrected,comments concerning BPS eqs. for NMG model in d>3 added in Sect.

Ocular Biometric Risk Factors for Progression of Primary Angle Closure Disease: The Zhongshan Angle Closure Prevention Trial

PURPOSE: To assess baseline ocular biometric risk factors for progression from primary angle closure suspect (PACS) to primary angle closure (PAC) or acute angle closure (AAC). DESIGN: Prospective observational study. PARTICIPANTS: 643 mainland Chinese aged 50 to 70 years with untreated PACS. METHODS: Participants received baseline clinical examinations including gonioscopy, anterior segment OCT (AS-OCT) imaging (Visante OCT, Carl Zeiss Meditec, Dublin, CA), and A-scan ultrasound biometry as part of the Zhongshan Angle Closure Prevention (ZAP) Trial. PACS was defined as inability to visualize pigmented trabecular meshwork in two or more quadrants based on static gonioscopy. PAC was defined as development of elevated intraocular pressure (IOP) > 24 mmHg or peripheral anterior synechiae (PAS). Progression was defined as development of PAC or an acute angle closure (AAC) attack. Multivariable logistic regression models were developed to assess biometric risk factors for progression. MAIN OUTCOME MEASURES: Progression from PACS to PAC or AAC over 6 years. RESULTS: 643 untreated eyes (609 non-progressors, 34 progressors) of 643 ZAP participants were included in the primary analysis. In a multivariable model with continuous parameters, narrower horizontal angle opening distance 500 μm from the scleral spur (AOD500; OR=1.10 per 0.01 mm decrease, p=0.03), flatter horizontal iris curvature (IC; OR=1.96 per 0.1 mm decrease, p=0.01), and older age (OR=1.11 per year increase, p=0.01) at baseline were significantly associated with progression (AUC=0.73). Smaller cumulative gonioscopy score was not associated with progression (OR=1.03 per 1 modified Shaffer grade decrease; p=0.85) when replacing horizontal AOD500 in the multivariable model. In a separate multivariable model with categorical parameters, participants in the lowest quartile of horizontal AOD500 (OR=3.10, p=0.002) and IC (OR=2.48, p=0.014) measurements and aged 59 years and older (OR=2.68, p=0.01) at baseline had higher odds of progression (AUC=0.72). CONCLUSIONS: Ocular biometric measurements can help risk stratify patients with early angle closure for more severe disease. AS-OCT measurements of biometric parameters describing the angle and iris are predictive of progression from PACS to PAC or AAC, whereas gonioscopy grades are not

Random walk with barriers: Diffusion restricted by permeable membranes

Restrictions to molecular motion by barriers (membranes) are ubiquitous in biological tissues, porous media and composite materials. A major challenge is to characterize the microstructure of a material or an organism nondestructively using a bulk transport measurement. Here we demonstrate how the long-range structural correlations introduced by permeable membranes give rise to distinct features of transport. We consider Brownian motion restricted by randomly placed and oriented permeable membranes and focus on the disorder-averaged diffusion propagator using a scattering approach. The renormalization group solution reveals a scaling behavior of the diffusion coefficient for large times, with a characteristically slow inverse square root time dependence. The predicted time dependence of the diffusion coefficient agrees well with Monte Carlo simulations in two dimensions. Our results can be used to identify permeable membranes as restrictions to transport in disordered materials and in biological tissues, and to quantify their permeability and surface area.Comment: 8 pages, 3 figures; origin of dispersion clarified, refs adde

Trends in Diabetic Retinopathy, Visual Acuity, and Treatment Outcomes for Patients Living With Diabetes in a Fundus Photograph-Based Diabetic Retinopathy Screening Program in Bangladesh

IMPORTANCE: Diabetic retinopathy (DR) is the leading cause of low vision among working-age adults. An estimated 6.9 million people in Bangladesh were living with diabetes in 2017, which is projected to increase to more than 10 million people in 2025. Currently, no standardized and/or large-scale DR screening program exists in Bangladesh. OBJECTIVE: To develop a novel fundus photograph–based eye screening model for early detection of DR to prevent vision loss in Bangladeshi individuals with diabetes. DESIGN, SETTING, AND PARTICIPANTS: In this cross-sectional study, 49 264 patients with diabetes underwent opportunistic eye screening at 2 eye hospitals and 1 diabetic hospital in Bangladesh between June 1, 2010, and September 30, 2017. The data set was analyzed from April 8 to December 30, 2018. Technicians were trained to obtain 2-field digital fundus photographs and to grade each according to a standardized DR severity scale. Each patient was counseled and triaged for treatment using defined DR referral criteria. MAIN OUTCOMES AND MEASURES: Primary DR grading outcomes, visual acuity, and treatment outcomes. RESULTS: A total of 49 264 patients (54.3% male; mean [SD] age, 50.8 [12.3] years) underwent DR screening during a 7-year period. The DR prevalence rate across all 3 sites was 33% (95% CI, 33%-33%). Prevalence rates varied by center (Chittagong, 64.6% [95% CI, 64.0%-65.0%]; Dhaka, 39.8% [95% CI, 39.0%-41.0%]; and Feni, 13.0% [95% CI, 13.0%-14.0%]). Across all age groups, male patients were at higher risk of prevalent DR than female patients (odds ratio, 1.99; 95% CI, 1.90-2.07). The prevalence was 3.9% for preproliferative DR, 7.8% for proliferative DR, and 19.2% for maculopathy. Individuals with DR had significantly worse visual acuity than those with no DR (bestcorrected visual acuity, 0.35 vs 0.21 logMAR; P < .001). The rate of moderate visual impairment was 12.2%, and the rate of blindness was 2.5%. Primary treatments included laser photocoagulation (n = 1637), intravitreal injection (n = 1440), and vitrectomy (n = 309). CONCLUSIONS AND RELEVANCE: Screening Bangladeshi individuals known to have diabetes using fundus photography identified large numbers of patients with sight-threatening proliferative DR, maculopathy, and visual impairment or blindness. Expansion of eye screening services in Bangladesh is warranted as part of a national government eye care and diabetes health polic

Accessibility-based reranking in multimedia search engines

Traditional multimedia search engines retrieve results based mostly on the query submitted by the user, or using a log of previous searches to provide personalized results, while not considering the accessibility of the results for users with vision or other types of impairments. In this paper, a novel approach is presented which incorporates the accessibility of images for users with various vision impairments, such as color blindness, cataract and glaucoma, in order to rerank the results of an image search engine. The accessibility of individual images is measured through the use of vision simulation filters. Multi-objective optimization techniques utilizing the image accessibility scores are used to handle users with multiple vision impairments, while the impairment profile of a specific user is used to select one from the Pareto-optimal solutions. The proposed approach has been tested with two image datasets, using both simulated and real impaired users, and the results verify its applicability. Although the proposed method has been used for vision accessibility-based reranking, it can also be extended for other types of personalization context

The Singapore Asymptomatic Narrow Angles Laser Iridotomy Study (ANA-LIS): 5 year results of a Randomized Controlled Trial

PURPOSE: To examine the efficacy of laser peripheral iridotomy (LPI) in subjects diagnosed as primary angle closure suspects (PACS) DESIGN: Prospective, randomized controlled trial PARTICIPANTS: This multi-center, randomized controlled trial (NCT00347178, Clinical trials.gov) enrolled 480 subjects over the age of 50 years from glaucoma clinics in Singapore with bilateral asymptomatic PACS (defined as having ≥2 quadrants of appositional angle closure on gonioscopy). METHODS: Each subject underwent prophylactic LPI in one randomly selected eye, while the fellow eye served as control. Subjects were followed up yearly for 5 years. MAIN OUTCOME MEASURES: The primary outcome measure was development of primary angle closure (PAC, defined as presence of peripheral anterior synechiae, and/or intraocular pressure>21 mmHg or acute angle closure [AAC]) or PACG over 5 years. RESULTS: Of the 480 randomized subjects, the majority were Chinese (92.7%) and female (75.8%) with mean age of 62.8±6.9 years. LPI-treated eyes reached endpoint less frequently after five years (24, 5.0%, incidence rate [IR]=11.65 per 1000 eye-years) compared to control eyes (45, 9.4%, IR=21.84 per 1000 eye-years, p=0.001). The adjusted hazards ratio (HR) for progression to PAC was 0.55 (95%CI: 0.37-0.83, p=0.004) in LPI-treated eyes compared to control eyes. Older subjects (per year, HR=1.06, 95%CI: 1.03-1.10, p<0.001) and eyes with higher baseline IOP (per mm Hg, HR=1.35, 95%CI: 1.22-1.50, p<0.0001) were more likely to reach an endpoint. The number needed to treat in order to prevent an endpoint was 22 (95%CI: 12.8-57.5). CONCLUSIONS: In subjects with bilateral asymptomatic PACS, eyes that underwent prophylactic LPI had significantly fewer endpoints compared to control eyes over 5 years. However, the overall incidence of PAC or PACG was low