A Semiconductor Under Insulator Technology in Indium Phosphide

This Letter introduces a Semiconductor-Under-Insulator (SUI) technology in InP for designing strip waveguides that interface InP photonic crystal membrane structures. Strip waveguides in InP-SUI are supported under an atomic layer deposited insulator layer in contrast to strip waveguides in silicon supported on insulator. We show a substantial improvement in optical transmission when using InP-SUI strip waveguides interfaced with localized photonic crystal membrane structures when compared with extended photonic crystal waveguide membranes. Furthermore, SUI makes available various fiber-coupling techniques used in SOI, such as sub-micron coupling, for planar membrane III-V systems

Giant Optical Non-linearity induced by a Single Two-Level System interacting with a Cavity in the Purcell Regime

A two-level system that is coupled to a high-finesse cavity in the Purcell regime exhibits a giant optical non-linearity due to the saturation of the two-level system at very low intensities, of the order of one photon per lifetime. We perform a detailed analysis of this effect, taking into account the most important practical imperfections. Our conclusion is that an experimental demonstration of the giant non-linearity should be feasible using semiconductor micropillar cavities containing a single quantum dot in resonance with the cavity mode.Comment: 40 pages, 16 figures, accepted in Phys. Rev.

Comparison of Outcomes between Endoscopic and Transcleral Cyclophotocoagulation.

Importance: Traditionally cyclophotocoagulation has been reserved as a treatment of last resort for eyes with advanced stage glaucoma, but increasingly it is offered to eyes with less severe disease. Endoscopic approaches in particular are utilized in increasing numbers of patients despite only a small number of publications on its results. Objective: The purpose of this study was to compare the efficacy and safety of endoscopic and transcleral cyclophotocoagulation (ECP and TCP) procedures in eyes with refractory glaucomas. Design, Setting, and Participants: A chart review was performed on consecutive patients who underwent ECP and TCP at a tertiary ophthalmology care center between January 2000 and December 2010. Cases with fewer than 3 months of follow-up or that had concurrent pressure reducing procedures were excluded. The main outcome measures examined were intraocular pressure (IOP), number of glaucoma medications, best corrected visual acuity (BCVA), additional glaucoma procedure required, and complications. Main Outcomes and Measures: Forty-two eyes (42 patients) that underwent ECP and forty-four eyes (44 patients) that underwent TCP were identified. The TCP group had a statistically higher mean age (71.2 ± 16.7 vs. 58.1 ± 22.9 years, respectively), larger proportion of neovascular glaucoma (40.9% vs. 16.7%), worse initial BCVA (logMAR 2.86 vs. 1.81), and higher preoperative IOP (45.3 vs. 26.6 mmHg) than the ECP group. At 12 months follow-up, the mean IOP difference between groups was not statistically significant, although the change in IOP from baseline to 12 months was greater for the TCP group (p = 0.006). The rates of progression to no light perception (NLP) and phthisis bulbi were significantly higher amongst TCP eyes than ECP eyes (27.2% vs. 4.8%, p = 0.017, and 20.5% vs. 0%, p = 0.003, respectively). Of these eyes that progressed, a majority had neovascular glaucoma (NVG). Corneal decompensation was the most frequent complication following ECP (11.9%). Conclusions and Relevance: In patients with preoperative BCVA of 20/400 or better, overall complication rates (cystoid macular edema, exudative retinal detachment, inflammation, cornea decompensation) were higher after ECP than with TCP. In refractory glaucomas in a real world setting (not a trial), TCP was more frequently used in ischemic eyes. TCP was associated with a higher rate of progression to phthisis bulbi and loss of light perception than ECP. However, ECP was associated with a clinically significant rate of corneal decompensation. These outcomes likely were related to the severity of underlying ocular diseases found in these eyes

Using error correction to determine the noise model

Quantum error correcting codes have been shown to have the ability of making quantum information resilient against noise. Here we show that we can use quantum error correcting codes as diagnostics to characterise noise. The experiment is based on a three-bit quantum error correcting code carried out on a three-qubit nuclear magnetic resonance (NMR) quantum information processor. Utilizing both engineered and natural noise, the degree of correlations present in the noise affecting a two-qubit subsystem was determined. We measured a correlation factor of c=0.5+/-0.2 using the error correction protocol, and c=0.3+/-0.2 using a standard NMR technique based on coherence pathway selection. Although the error correction method demands precise control, the results demonstrate that the required precision is achievable in the liquid-state NMR setting.Comment: 10 pages, 3 figures. Added discussion section, improved figure

Haiti: coffee and mango production in a changing climate

Coffee and mango contribute significantly to Haiti’s agricultural gross domestic product and export revenues. Generating income valued at US$11 million in 2011, mango has become one of the country’s most important export commodities. In contrast, coffee exports steadily declined from$7 million to $1 million between 2000 and 2010, even though demand for high-quality Haitian coffee has actually increased on the global market. A recent study conducted by the International Center for Tropical Agriculture (CIAT) and Catholic Relief Services (CRS) revealed that future changes in temperature and rainfall patterns will have significant effects on the suitability of coffee and mango for production in Haiti. While mango will continue to be highly viable, coffee will become considerably less suitable for production at lower elevations. Changing climatic conditions could also lower quality and yields in current coffee-producing regions, such as Plaisance and Dondon in the North and Beaumont in the Southwest. To cope with the challenges that coffee and mango growers are likely to face, it will be important to promote the diversification of agricultural systems, introduce improved coffee varieties, offer financial incentives to adopt sustainable land use practices, build capacity among smallholders, and foster the sharing of expertise

To bend or not to bend – are heteroatom interactions within conjugated molecules effective in dictating conformation and planarity?

We consider the roles of heteroatoms (mainly nitrogen, the halogens and the chalcogens) in dictating the conformation of linear conjugated molecules and polymers through non-covalent intramolecular interactions. Whilst hydrogen bonding is a competitive and sometimes more influential interaction, we provide unambiguous evidence that heteroatoms are able to determine the conformation of such materials with reasonable predictability

Point de vue masculin sur la pornographie : des fantasmes à la réalité

Objectifs. — Documenter les effets de l’utilisation de la pornographie sur les scripts, carrière sexuelle, et relations intimes de jeunes hommes. Méthodologie. — Dans un souci de neutralité et pour éviter le plus possible tout a priori, cette recherche utilise la construction empirique de la théorie, afin d’aller au-delà des idées préconçues au sujet de la pornographie. Dans le cadre d’entrevues semi-dirigées, nous donnons la parole à 20 jeunes hommes hétérosexuels de 18 à 25 ans, afin de documenter les effets de l’utilisation de la pornographie surleursscripts etleur carrière sexuels, ainsi que surleursrelations intimes. Résultats. — Pour certains jeunes, elle serait, au début, une forme d’éducation sexuelle. Pour d’autres encore, elle n’acquiert de signification érotique que plus tard. Par la suite, la pornographie constituerait un moyen de visualiser desfantasmes qu’ils avaient déjà imaginés, et elle leur fournirait parfois des manières précises de les réaliser. Discussion. — Pour plusieurs, la masturbation et pornographie se confondent. Information, éducation, satisfaction d’une curiosité ou excitation, la fonction de la pornographie ne se résumerait, aux yeux des jeunes hommes, qu’à un moment d’évasion, ceux-ci n’accordant en définitive que peu de crédibilité à cette forme d’imagerie. Conclusion. — Ilsemble en fait que l’usage de la pornographie s’inscrive dans une relation dynamique et diachronique chez les jeunes. Cette recherche permet de concevoir des interventions adaptées aux problématiques masculines.Objectives. —To document the impact of pornography use upon the sexual scripts of young men as well as upon their sexual careers and intimate relationships. Methodology. —For the sake of remaining neutral, and to avoid as much as possible any a priori, this research uses the grounded theory to go beyond the usual preconception about pornography. Twenty young heterosexuals between 18 and 25 were given the chance to express themselves on these subjects during 20 partially supervised interviews. Results. —For some of them, pornography seems to be a form of initial sexual education. For others, its erotic aspect appears only later. Discussion. —Itseemsthat after a certain time, pornography is used to visualize some old fantasies 2 and,sometimes, to materialize them. For many of them, masturbation and pornography merge. Conclusion. —No matter its function—information, education, satisfaction of a curiosity or arousal—, pornography seems only to amount to some sort of momentary escape, as these young men do not give much credit to this form of fantasy. In fact, it seems that pornography use is part of a dynamic and diachronic relation in young people. This research allows the development of interventions specifically adapted to masculinity issues

Why the two-pulse photon echo is not a good quantum memory protocol

We consider in this paper a two-pulse photon echo sequence as a potential quantum light storage protocol. It is widely believed that a two-pulse scheme should lead to very low efficiency and is then not relevant for this specific application. We show experimentally by using a Tm${}^{3+}$:YAG crystal that such a protocol is on contrary very efficient and even too efficient to be considered as a good quantum storage protocol. Our experimental work allows us to point out on one side the real limitations of this scheme and on the other side its benefits which can be a source of inspiration to conceive more promising procedures with rare-earth ion doped crystals