Single photon emission and detection at the nanoscale utilizing semiconductor nanowires

We report recent progress toward on-chip single photon emission and detection in the near infrared utilizing semiconductor nanowires. Our single photon emitter is based on a single InAsP quantum dot embedded in a p-n junction defined along the growth axis of an InP nanowire. Under forward bias, light is emitted from the single quantum dot by electrical injection of electrons and holes. The optical quality of the quantum dot emission is shown to improve when surrounding the dot material by a small intrinsic section of InP. Finally, we report large multiplication factors in excess of 1000 from a single Si nanowire avalanche photodiode comprised of p-doped, intrinsic, and n-doped sections. The large multiplication factor obtained from a single Si nanowire opens up the possibility to detect a single photon at the nanoscale.Comment: 11 pages, 7 figure

Autorenidentifikation für wissenschaftliche Publikationen. Bericht über den Workshop der DINI-AG Elektronisches Publizieren auf dem 6. Bibliothekskongress

Identifikationssysteme für Autorinnen und Autoren spielen für das wissenschaftliche Publizieren eine zentrale Rolle. Sie erlauben die eindeutige Zuordnung von Publikationen zu ihren Urheberinnen und Urhebern, ermöglichen - auch auf übergreifenden Plattformen - gezielte Rechercheeinstiege und unterstützen die semantische Verknüpfung im Netz. Darüber hinaus können Autorenidentifikationssysteme zur einfachen Pflege von Publikationslisten und für die Forschungsevaluation genutzt werden. Neben zahlreichen proprietären Systemen von Verlagen und Datenbankbetreibern widmet sich im Wissenschaftsbereich die global agierende Initiative ORCID (Open Researcher and Contributer ID) der Vergabe einer eindeutigen ID für Forschende. Im deutschen Bibliothekswesen kommt zur Erschließung mit Personenbezug vor allem der Gemeinsamen Normdatei (GND) entscheidende Bedeutung zu. In den Open-Access-Repositorien deutscher Hochschulen und Forschungseinrichtungen hat sich die Verwendung übergreifender Autorenidentifikationssystemen dagegen bislang kaum durchgesetzt. Im Rahmen des 6. Bibliothekskongresses veranstaltete die AG Elektronisches Publizieren der Deutschen Initiative für Netzwerkinformation (DINI) am 15.03.2016 einen Workshop zu diesem Themenfeld. Die Referentinnen und Referenten haben das Thema Autorenidentifikation und deren Anwendungsszenarien aus unterschiedlichen Blickwinkeln beleuchtet. Der vorliegende Beitrag gibt einen Überblick über die Themen des Workshops

Post-contrast acute kidney injury \u2013 Part 1: Definition, clinical features, incidence, role of contrast medium and risk factors: Recommendations for updated ESUR Contrast Medium Safety Committee guidelines

Purpose: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 2011 guidelines on the prevention of post-contrast acute kidney injury (PC-AKI). The results of the literature review and the recommendations based on it, which were used to prepare the new guidelines, are presented in two papers. Areas covered in part 1: Topics reviewed include the terminology used, the best way to measure eGFR, the definition of PC-AKI, and the risk factors for PC-AKI, including whether the risk with intravenous and intra-arterial contrast medium differs. Key Points: \u2022 PC-AKI is the preferred term for renal function deterioration after contrast medium. \u2022 PC-AKI has many possible causes. \u2022 The risk of AKI caused by intravascular contrast medium has been overstated. \u2022 Important patient risk factors for PC-AKI are CKD and dehydration

Post-contrast acute kidney injury. Part 2: risk stratification, role of hydration and other prophylactic measures, patients taking metformin and chronic dialysis patients: Recommendations for updated ESUR Contrast Medium Safety Committee guidelines

Objectives: The Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR) has updated its 2011 guidelines on the prevention of post-contrast acute kidney injury (PC-AKI). The results of the literature review and the recommendations based on it, which were used to prepare the new guidelines, are presented in two papers. Areas covered in part 2: Topics reviewed include stratification of PC-AKI risk, the need to withdraw nephrotoxic medication, PC-AKI prophylaxis with hydration or drugs, the use of metformin in diabetic patients receiving contrast medium and the need to alter dialysis schedules in patients receiving contrast medium. Key points: \u2022 In CKD, hydration reduces the PC-AKI risk \u2022 Intravenous normal saline and intravenous sodium bicarbonate provide equally effective prophylaxis \u2022 No drugs have been consistently shown to reduce the risk of PC-AKI \u2022 Stop metformin from the time of contrast medium administration if eGFR < 30 ml/min/1.73 m2 \u2022 Dialysis schedules need not change when intravascular contrast medium is given

A lepto-hadronic model for high-energy emission from FR I radiogalaxies

The well know radiogalaxy Cen A has been recently detected as a source of very high energy (VHE) gamma-rays by the HESS experiment just before Fermi/LAT detected it at high energies (HE). The detection, together with that of M87, establishes radiogalaxies as VHE gamma-ray emitters. The aim of this work is to present a lepto-hadronic model for the VHE emission from the relativistic jets in FR I radiogalaxies. We consider that protons and electrons are accelerated in a compact region near the base of the jet, and they cool emitting multi wavelength radiation as they propagate along the jet. The proton and electron distributions are obtained through an inhomogeneous steady-state transport equation taking into account acceleration, radiative and non-radiative cooling processes, as well as particle transport by convection. Considering the effects of photon absorption at different wavelengths, we calculate the radiation emitted by the primary protons and electrons, as well as the contribution of secondaries particles (e+/-, pions and muons). The expected high-energy neutrino signal is also obtained and the possibility of detections with KM3Net and IceCube is discussed. The spectral energy distribution obtained in our model with an appropriate set of parameters for an extended emission zone can account for much of the observed spectrum for both AGNs.Comment: 16 pages, 11 figures, accepted for publication in A&A. New and revised calculations were adde

Measuring the non-thermal pressure in early type galaxy atmospheres: A comparison of X-ray and optical potential profiles in M87 and NGC1399

We compare the gravitational potential profiles of the elliptical galaxies NGC 4486 (M87) and NGC 1399 (the central galaxy in the Fornax cluster) derived from X-ray and optical data. This comparison suggests that the combined contribution of cosmic rays, magnetic fields and micro-turbulence to the pressure is ~10% of the gas thermal pressure in the cores of NGC 1399 and M87, although the uncertainties in our model assumptions (e.g., spherical symmetry) are sufficiently large that the contribution could be consistent with zero. In the absence of any other form of non-thermal pressure support, these upper bounds translate into upper limits on the magnetic field of ~10-20 muG at a distance of 1'-2' from the centers of NGC1399 and M87. We show that these results are consistent with the current paradigm of cool cluster cores, based on the assumption that AGN activity regulates the thermal state of the gas by injecting energy into the intra-cluster medium. The limit of ~10-20% on the energy density in the form of relativistic protons applies not only to the current state of the gas, but essentially to the entire history of the intra-cluster medium, provided that cosmic ray protons evolve adiabatically and that their spatial diffusion is suppressed.Comment: Accepted for MNRAS. 19 pages; 14 figures; expanded version in response to comments from the refere

Consensus statement on measures to promote equitable authorship in the publication of research from international partnerships

Despite the acknowledged injustice and widespread existence of parachute research studies conducted in low- or middle-income countries by researchers from institutions in high-income countries, there is currently no pragmatic guidance for how academic journals should evaluate manuscript submissions and challenge this practice. We assembled a multidisciplinary group of editors and researchers with expertise in international health research to develop this consensus statement. We reviewed relevant existing literature and held three workshops to present research data and holistically discuss the concept of equitable authorship and the role of academic journals in the context of international health research partnerships. We subsequently developed statements to guide prospective authors and journal editors as to how they should address this issue. We recommend that for manuscripts that report research conducted in low- or middle-income countries by collaborations including partners from one or more high-income countries, authors should submit accompanying structured reflexivity statements. We provide specific questions that these statements should address and suggest that journals should transparently publish reflexivity statements with accepted manuscripts. We also provide guidance to journal editors about how they should assess the structured statements when making decisions on whether to accept or reject submitted manuscripts. We urge journals across disciplines to adopt these recommendations to accelerate the changes needed to halt the practice of parachute research

Consensus statement on measures to promote equitable authorship in the publication of research from international partnerships

Summary: Despite the acknowledged injustice and widespread existence of parachute research studies conducted in low‐ or middle‐income countries by researchers from institutions in high‐income countries, there is currently no pragmatic guidance for how academic journals should evaluate manuscript submissions and challenge this practice. We assembled a multidisciplinary group of editors and researchers with expertise in international health research to develop this consensus statement. We reviewed relevant existing literature and held three workshops to present research data and holistically discuss the concept of equitable authorship and the role of academic journals in the context of international health research partnerships. We subsequently developed statements to guide prospective authors and journal editors as to how they should address this issue. We recommend that for manuscripts that report research conducted in low‐ or middle‐income countries by collaborations including partners from one or more high‐income countries, authors should submit accompanying structured reflexivity statements. We provide specific questions that these statements should address and suggest that journals should transparently publish reflexivity statements with accepted manuscripts. We also provide guidance to journal editors about how they should assess the structured statements when making decisions on whether to accept or reject submitted manuscripts. We urge journals across disciplines to adopt these recommendations to accelerate the changes needed to halt the practice of parachute research