University of Geneva

About: University of Geneva is a education organization based out in Geneva, Switzerland. It is known for research contribution in the topics: Population & Planet. The organization has 26887 authors who have published 65265 publications receiving 2931373 citations. The organization is also known as: Geneva University & Universite de Geneve.

Genome-wide association study in individuals of South Asian ancestry identifies six new type 2 diabetes susceptibility loci

Abstract: John Chambers and colleagues report a genome-wide association study for type 2 diabetes in individuals of south Asian ancestry. They identify six loci newly associated with type 2 diabetes.

Melanomas require HEDGEHOG-GLI signaling regulated by interactions between GLI1 and the RAS-MEK/AKT pathways.

Abstract: Melanoma is one of the most aggressive cancers, and its incidence is increasing. These tumors derive from the melanocyte lineage and remain incurable after metastasis. Here we report that SONIC HEDGEHOG (SHH)-GLI signaling is active in the matrix of human hair follicles, and that it is required for the normal proliferation of human melanocytes in culture. SHH-GLI signaling also regulates the proliferation and survival of human melanomas: the growth, recurrence, and metastasis of melanoma xenografts in mice are prevented by local or systemic interference of HH-GLI function. Moreover, we show that oncogenic RAS-induced melanomas in transgenic mice express Gli1 and require Hh-Gli signaling in vitro and in vivo. Finally, we provide evidence that endogenous RAS-MEK and AKT signaling regulate the nuclear localization and transcriptional activity of GLI1 in melanoma and other cancer cells. Our data uncover an unsuspected role of HH-GLI signaling in melanocytes and melanomas, demonstrate a role for this pathway in RAS-induced tumors, suggest a general integration of the RAS/AKT and HH-GLI pathways, and open a therapeutic approach for human melanomas.

Quantum cryptography using entangled photons in energy-time bell states

Abstract: We present a setup for quantum cryptography based on photon pairs in energy-time Bell states and show its feasibility in a laboratory experiment. Our scheme combines the advantages of using photon pairs instead of faint laser pulses and the possibility to preserve energy-time entanglement over long distances. Moreover, using four-dimensional energy-time states, no fast random change of bases is required in our setup: Nature itself decides whether to measure in the energy or in the time base, thus rendering eavesdropper attacks based on “photon number splitting” less efficient. PACS numbers: 03.67.Dd, 03.67.Hk Quantum communication is probably one of the most rapidly growing and most exciting fields of physics within the last years [1]. Its most mature application is quantum cryptography [also called quantum key distribution (QKD)], ensuring the distribution of a secret key between two parties. This key can be used afterwards to encrypt and decrypt secret messages using the one time pad [2]. In opposition to the mostly used “public key” systems [2], the security of quantum cryptography is not based on mathematical complexity, but on an inherent property of single quanta. Roughly speaking, since it is not possible to measure an unknown quantum system without modifying it, an eavesdropper manifests herself by introducing errors in the transmitted data. During the past years, several prototypes based on faint laser pulses have been developed, demonstrating that quantum cryptography not only works inside the laboratory, but in the “real world” as well [1,3,4]. Besides, it has been shown that two-photon entanglement can be preserved over large distances [5], especially when being entangled in energy and time [6]. As pointed out by Ekert in 1991 [7], the nonlocal correlations engendered by such states can also be used to establish sequences of correlated bits at distant places. Besides improvements in the domain of QKD, recent experimental progress in generating, manipulating, and measuring the so-called Bell states [8], has lead to fascinating applications like quantum teleportation [9], dense coding [10], and entanglement swapping [11]. In a recent paper, we proposed and tested a novel source for quantum communication generating a new kind of Bell states based on energy-time entanglement [12]. In this paper, we present a first application, exploiting this new source for quantum cryptography. Our scheme follows Ekert’s initial idea concerning the use of photon-pair correlations. However, in opposition, it implements Bell states and can thus be seen in the broader context of quantum communication. Moreover, the fact that energy-time entanglement can be preserved over long distances renders our source particulary interesting for long-distance applications. To understand the principle of our idea, we look at Fig. 1. A short light pulse emitted at time t0 enters an interferometer having a path length difference which is large compared to the duration of the pulse. The pulse is thus split into two pulses of smaller amplitudes, following each other with a fixed phase relation. The light is then focused into a nonlinear crystal where some of the pump photons are down-converted into photon pairs. Working with pump energies low enough to ensure that generation of two photon pairs can be neglected, a created photon pair is described by jc 1 p 2 jsPjsP 1 e if jlPjlP . (1)

Depression comorbid with anxiety: results from the WHO study on psychological disorders in primary health care

Abstract: The World Health Organization collaborative study on "Psychological Problems in General Health Care" investigated the form, frequency, course and outcome of common psychological problems in primary care settings at 15 international sites. The research employed a two-stage case-finding procedure. GHQ-12 was administered to 25916 adults who consulted health-care services. The second-stage assessment (n = 5438) consisted of the Composite international Diagnostic Interview (CIDI), the Social Disability Schedule, and questionnaires. Possible cases or borderline cases of mental disorder, and a sample of known cases, were followed up at three months and one year. Using standard diagnostic algorithms (ICD-10), prevalence rates were calculated for current disorder (one-month) and lifetime experience disorder. Well-defined psychological problems are frequent in all the general health-care settings examined (median 24.0%). Among the most common were depression anxiety, alcohol misuse, somatoform disorders, and neurasthenia. Nine per cent of patients suffered from a "subthreshold condition" that did not meet diagnostic criteria but had clinically significant symptoms and functional impairment. The most common co-occurrence was depression and anxiety. Comorbidity increases the likelihood of recognition of mental disorders in general health care, and the likelihood of receiving treatment.