Nonlinear surface impurity in a semi-infinite 2D square lattice

We examine the formation of localized states on a generalized nonlinear impurity located at, or near the surface of a semi-infinite 2D square lattice. Using the formalism of lattice Green functions, we obtain in closed form the number of bound states as well as their energies and probability profiles, for different nonlinearity parameter values and nonlinearity exponents, at different distances from the surface. We specialize to two cases: impurity close to an "edge" and impurity close to a "corner". We find that, unlike the case of a 1D semi-infinite lattice, in 2D, the presence of the surface helps the formation of a localized state.Comment: 6 pages, 7 figures, submitted to PR

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

Uveal melanoma and macular degeneration : Molecular biology and potential therapeutic applications

Uveal melanoma is the most common primary intraocular malignant tumor in adults with 30% to 50% of patients that ultimately succumb to metastatic disease, mainly to the liver. Although new diagnostic and therapeutic tools have been developed during the most recent years, only the eye conservation rate has been achieved, while the survival rate remains poor. Neovascular age-related macular degeneration (AMD) is a disease where abnormal blood vessels grow in the macula and cause blindness and is the leading cause for legal blindness in many industrialised countries. Angiogenesis and more specifically growth factors are thought to be responsible for the development of both tumors and neovascular AMD. The aim of the study was to identify prognostic markers for uveal melanoma and potential new therapeutic applications for both uveal melanoma and exudative AMD. Paraffin-embedded tumor specimens from 132 patients with primary uveal melanoma were analyzed with immunohistochemistry by using well-established specific antibodies against c-Met and IGF-1R. We found that the expression of both IGF-1R and c-Met was significantly associated with melanoma-specific mortality while IGF-1R showed to be a stronger prognostic marker than other currently used such as tumor cell type and tumor diameter. That could suggest a possible role of these two receptors in the spread of uveal melanoma while IGF-1R could be considered as prognostic tool and a therapeutic target. The elevated mortality rate of uveal melanoma is due to a high incidence of metastases, which occur preferentially in the liver. We showed that intraperitoneal injections of picropodophyllin (PPP), an inhibitor of IGF-1R, efficiently blocks uveal melanoma growth in vitro using different uveal melanoma cell lines and in vivo in uveal melanoma xenografts. Furthermore PPP inhibited several mechanisms involved in metastasis, including tumor cell adhesion to extracellular matrix proteins, activity and expression of matrix metalloproteinase 2, and also significantly reduced the number of the micrometastases to the liver. Oral chemotherapy generally represents a fundamental change and challenge at the same time in contemporary oncology practice. We demonstrated that oral administration of PPP completely blocks the growth of uveal melanoma xenografts and was well tolerated by the mice. PPP also reduced expression of IGF-1 dependent VEGF in uveal melanoma tumors. This effect and the anti-angiogenic response probably contribute to the high anti-tumor efficacy of PPP. PPP was also found to be superior to the other anti-tumor agents such as imatinib mesylate, cisplatin, 5-FU and doxorubicin in killing uveal melanoma cells. We could only detect a limited synergistic effect with some of them in combination with PPP. There is now compelling evidence that targeting angiogenesis in general and VEGF signaling in particular is a meaningful approach for the therapy of both cancer and exudative AMD. We could show that PPP efficiently reduces experimental CNV and inhibits the VEGF secretion from RPE cells. This thesis highlights the possibility of using IGF-1R as a prognostic marker for uveal melanoma as well as that targeting the receptor with inhibitors like PPP could offer a useful option in therapy of uveal melanoma and exudative AMD

Kahook dual-blade goniotomy with and without phacoemulsification in medically uncontrolled glaucoma

Purpose: To evaluate the 2-year efficacy and safety of Kahook dual-blade (KDB) goniotomy in patients with medically uncontrolled glaucoma. Methods: This was a retrospective case-series study of 90 consecutive patients with primary open-angle glaucoma (POAG) or pseudoexfoliation glaucoma (PEXG) that underwent KDB goniotomy alone (KDB-alone group) or KDB goniotomy in combination with phacoemulsification (KDB-phaco group) during 2019–2020. All patients were uncontrolled on three or more medications. Surgical success was defined as an IOP reduction ≥20% and/or a reduction of one or more medications at 24 months. We also report IOP levels and number of medications from baseline to 24 months, as well as the need for further glaucoma interventions. Results: At 24 months, mean IOP had reduced from 24.8±8.3 to 15.0±5.3 mmHg in the KDB-alone group (P&lt;0.001) and from 22.3 ±5.8 to 13.9±3.0 mmHg in the KDB-phaco group (P&lt;0.001). Medications had reduced from 3.5±0.6 to 3.1±0.9 in the KDB-alone group (P=0.047) and from 3.3±0.5 to 2.3±1.1 in the KDB-phaco group (P&lt;0.001). An IOP reduction ≥20% and/or a reduction with one or more medications was achieved by 47% of eyes in the KDB-alone group and by 76% of eyes in the KDB-phaco group. Eyes with PEXG and POAG responded equally well to the success criteria. During the 24-month follow-up, additional glaucoma surgery or transscleral photocoagulation was performed in 28% of eyes in the KDB-alone group and in 12% of eyes in the KDB-phaco group. Conclusion: In patients with medically uncontrolled glaucoma, KDB had a significant IOP-lowering effect after 24 months, but success rates were higher when KDB was performed in combination with cataract surgery compared to stand-alone treatment

Better tolerance of preservative-free latanoprost compared to preserved glaucoma eye drops: The 12-month real-life FREE study

Background: Lack of efficacy due to bad compliance caused by intolerance issues is the main reason for a change to a better tolerated ocular treatment, such as using preservative-free (PF) eye drops. Aim: To assess the efficacy and local tolerance after 12 months and patient satisfaction regarding local treatment tolerance and handling at inclusion and after 6 months of PF latanoprost compared to preserved glaucoma eye drops. Methods: This was an international, prospective, and observational real-life study. Up to three visits, one at inclusion and two follow-up visits (one after 6 and one after 12 months) were planned. Efficacy, local tolerance, and patient satisfaction were the main evaluation criteria. Results: Data from 721 patients were available for the statistical analysis. Overall, 64.8% (467/721) of patients switched treatment before inclusion: 62.2% in the preserved and 68.9% in the PF latanoprost group. IOP values were similar between PF latanoprost and preserved eye drops and remained stable at all visits. Ocular signs and symptoms improved after switching to PF latanoprost; the prevalence of conjunctival hyperemia was significantly lower (P=0.0015) at both follow-up visits. At follow-up visit 1, 49.5% of the patients who switched to PF latanoprost decreased or stopped the use of artificial tears. Satisfaction regarding tolerance in patients using PF latanoprost improved significantly after the switch from preserved eye drops to PF latanoprost (88.9% and 42.5%, respectively, P<0.0001). Conclusion: This first real-life study showed that PF latanoprost was as efficacious but better tolerated than preserved eye drops over a sustained period of 12 months, while providing a significantly higher patient satisfaction and potentially allowing improvement in the patient’s daily life

A Review on Pathogens and Necessary Diagnostic Work for Bleb-Related Infections (BRIs)

At the present time, as newer techniques and minimally invasive procedures gain popularity among anterior segment surgeons for regulating intraocular pressure, trabeculectomy still has a leading role in glaucoma surgery. Trabeculectomy retains a highly successful and safe profile; however, one of the major complications includes bleb-related infections (BRIs). To date, the most common pathogens remain Gram-positive cocci, but the list of pathogens that have been identified in the literature includes more than 100 microorganisms. Because antibiotic use is more widespread than ever before and our ability to identify pathogens has improved, the pathogen spectrum will broaden in the future and more pathogens causing BRIs will be described as atypical presentations. The scope of this review was to identify all pathogens that have been described to cause bleb-related infections to date, as well as focus on the risk factors, clinical presentation, and various available diagnostic tools used for an appropriate diagnostic workup

European study of the efficacy of a cross-linked gel stent for the treatment of glaucoma

indexation en cours.International audiencePURPOSE: This study investigated the efficacy and safety of a cross-linked collagen stent (XEN 45) with or without cataract surgery in the treatment of glaucoma. SETTING: Real-life setting. DESIGN: Prospective, open-label, multicenter clinical trial. METHODS: Eligible patients with glaucoma inadequately controlled by treatment, or poor compliance or intolerance to topical therapy were included. Patients were divided into those with implant only (solo group; phakic and pseudophakic patients) and implant combined with cataract surgery (combo group). Differences in average intraocular pressure (IOP) and number of medications between baseline and study end (12 months), and the rate of qualified and complete success were evaluated. RESULTS: Overall, there were 115 patients in the solo group (43 phakic and 72 pseudophakic) and 56 in the combo group. Compared with baseline, mean IOP (23.9 +/- 7.6 to 15.5 +/- 3.9) and number of medications (3.0 +/- 1.1 to 0.5 +/- 1.0) decreased significantly at study end (P 20% and >30% reduction in IOP from baseline was achieved by 72.3% and 52.6% of patients, respectively. IOP at one week post-op was a predictor of success, and the needling rate was inversely correlated to early post-op IOP. The number of pre-operative medications and patientage were not significantly associated with failure. CONCLUSIONS: Insertion of the XEN 45 stent alone or combined with phacoemulsification is effective and safe in the treatment of open angle glaucoma, with a substantial reduction in IOP and number of medications. Future randomized, comparative studies on the use of this device are warranted