APDs as Single-Photon Detectors for Visible and Near-Infrared Wavelenghts down to Hz Rates

For the SPECTRAP experiment at GSI, Germany, detectors with Single-Photon counting capability in the visible and near-infrared regime are required. For the wavelength region up to 1100 nm we investigate the performance of 2x2 mm^2 avalanche photo diodes (APDs) of type S0223 manufactured by Radiation Monitoring Devices. To minimize thermal noise, the APDs are cooled to approximately -170 deg. C using liquid nitrogen. By operating the diodes close to the breakdown voltage it is possible to achieve relative gains in excess of 2x10^4. Custom-made low noise preamplifiers are used to read out the devices. The measurements presented in this paper have been obtained at a relative gain of 2.2x10^4. At a discriminator threshold of 6 mV the resulting dark count rate is in the region of 230/s. With these settings the studied APDs are able to detect single photons at 628 nm wavelength with a photo detection efficiency of (67+-7)%. Measurements at 1020 nm wavelength have been performed using the attenuated output of a grating spectrograph with a light bulb as photon source. With this setup the photo detection efficiency at 1020 nm has been determined to be (13+-3)%, again at a threshold of 6 mV.Comment: 14 pages, 9 figures, submitted to Journal of Instrumentatio

APDs as Single-Photon Detectors for Visible and Near-Infrared Wavelenghts down to Hz Rates

For the SPECTRAP experiment at GSI, Germany, detectors with Single-Photon counting capability in the visible and near-infrared regime are required. For the wavelength region up to 1100 nm we investigate the performance of 2x2 mm^2 avalanche photo diodes (APDs) of type S0223 manufactured by Radiation Monitoring Devices. To minimize thermal noise, the APDs are cooled to approximately -170 deg. C using liquid nitrogen. By operating the diodes close to the breakdown voltage it is possible to achieve relative gains in excess of 2x10^4. Custom-made low noise preamplifiers are used to read out the devices. The measurements presented in this paper have been obtained at a relative gain of 2.2x10^4. At a discriminator threshold of 6 mV the resulting dark count rate is in the region of 230/s. With these settings the studied APDs are able to detect single photons at 628 nm wavelength with a photo detection efficiency of (67+-7)%. Measurements at 1020 nm wavelength have been performed using the attenuated output of a grating spectrograph with a light bulb as photon source. With this setup the photo detection efficiency at 1020 nm has been determined to be (13+-3)%, again at a threshold of 6 mV.Comment: 14 pages, 9 figures, submitted to Journal of Instrumentatio

APDs as Single-Photon Detectors for Visible and Near-Infrared Wavelenghts down to Hz Rates

For the SPECTRAP experiment at GSI, Germany, detectors with Single-Photon counting capability in the visible and near-infrared regime are required. For the wavelength region up to 1100 nm we investigate the performance of 2x2 mm^2 avalanche photo diodes (APDs) of type S0223 manufactured by Radiation Monitoring Devices. To minimize thermal noise, the APDs are cooled to approximately -170 deg. C using liquid nitrogen. By operating the diodes close to the breakdown voltage it is possible to achieve relative gains in excess of 2x10^4. Custom-made low noise preamplifiers are used to read out the devices. The measurements presented in this paper have been obtained at a relative gain of 2.2x10^4. At a discriminator threshold of 6 mV the resulting dark count rate is in the region of 230/s. With these settings the studied APDs are able to detect single photons at 628 nm wavelength with a photo detection efficiency of (67+-7)%. Measurements at 1020 nm wavelength have been performed using the attenuated output of a grating spectrograph with a light bulb as photon source. With this setup the photo detection efficiency at 1020 nm has been determined to be (13+-3)%, again at a threshold of 6 mV.Comment: 14 pages, 9 figures, submitted to Journal of Instrumentatio

Can preferential credit programs speed up the adoption of low-carbon agricultural systems in Mato Grosso, Brazil? Results from bioeconomic microsimulation

The need to balance agricultural production and environmental protection shifted the focus of Brazilian land-use policy toward sustainable agriculture. In 2010, Brazil established preferential credit lines to finance investments into low-carbon integrated agricultural systems of crop, livestock and forestry. This article presents a simulation-based empirical assessment of integrated system adoption in the state of Mato Grosso, where highly mechanized soybean–cotton and soybean–maize doublecrop systems currently prevail. We employ bioeconomic modeling to explicitly capture the heterogeneity of farm level costs and benefits of adoption. By parameterizing and validating our simulations with both empirical and experimental data, we evaluate the effectiveness of the ABC Integration credit through indicators such as land-use change, adoption rates and budgetary costs of credit provision. Alternative scenarios reveal that specific credit conditions might speed up the diffusion of low-carbon agricultural systems in Mato Grosso

Subtle motor disturbances in PREDICT-PD participants

PREDICT-PD has been funded by Parkinson’'s UK (reference F1201)

Sleep, vigilance, and thermosensitivity

The regulation of sleep and wakefulness is well modeled with two underlying processes: a circadian and a homeostatic one. So far, the parameters and mechanisms of additional sleep-permissive and wake-promoting conditions have been largely overlooked. The present overview focuses on one of these conditions: the effect of skin temperature on the onset and maintenance of sleep, and alertness. Skin temperature is quite well suited to provide the brain with information on sleep-permissive and wake-promoting conditions because it changes with most if not all of them. Skin temperature changes with environmental heat and cold, but also with posture, environmental light, danger, nutritional status, pain, and stress. Its effect on the brain may thus moderate the efficacy by which the clock and homeostat manage to initiate or maintain sleep or wakefulness. The review provides a brief overview of the neuroanatomical pathways and physiological mechanisms by which skin temperature can affect the regulation of sleep and vigilance. In addition, current pitfalls and possibilities of practical applications for sleep enhancement are discussed, including the recent finding of impaired thermal comfort perception in insomniacs

The 2010 very high energy gamma-ray flare & 10 years of multi-wavelength observations of M 87

Abridged: The giant radio galaxy M 87 with its proximity, famous jet, and very massive black hole provides a unique opportunity to investigate the origin of very high energy (VHE; E>100 GeV) gamma-ray emission generated in relativistic outflows and the surroundings of super-massive black holes. M 87 has been established as a VHE gamma-ray emitter since 2006. The VHE gamma-ray emission displays strong variability on timescales as short as a day. In this paper, results from a joint VHE monitoring campaign on M 87 by the MAGIC and VERITAS instruments in 2010 are reported. During the campaign, a flare at VHE was detected triggering further observations at VHE (H.E.S.S.), X-rays (Chandra), and radio (43 GHz VLBA). The excellent sampling of the VHE gamma-ray light curve enables one to derive a precise temporal characterization of the flare: the single, isolated flare is well described by a two-sided exponential function with significantly different flux rise and decay times. While the overall variability pattern of the 2010 flare appears somewhat different from that of previous VHE flares in 2005 and 2008, they share very similar timescales (~day), peak fluxes (Phi(>0.35 TeV) ~= (1-3) x 10^-11 ph cm^-2 s^-1), and VHE spectra. 43 GHz VLBA radio observations of the inner jet regions indicate no enhanced flux in 2010 in contrast to observations in 2008, where an increase of the radio flux of the innermost core regions coincided with a VHE flare. On the other hand, Chandra X-ray observations taken ~3 days after the peak of the VHE gamma-ray emission reveal an enhanced flux from the core. The long-term (2001-2010) multi-wavelength light curve of M 87, spanning from radio to VHE and including data from HST, LT, VLA and EVN, is used to further investigate the origin of the VHE gamma-ray emission. No unique, common MWL signature of the three VHE flares has been identified.Comment: 19 pages, 5 figures; Corresponding authors: M. Raue, L. Stawarz, D. Mazin, P. Colin, C. M. Hui, M. Beilicke; Fig. 1 lightcurve data available online: http://www.desy.de/~mraue/m87

Pluto's lower atmosphere and pressure evolution from ground-based stellar occultations, 1988-2016

Context. The tenuous nitrogen (N2) atmosphere on Pluto undergoes strong seasonal effects due to high obliquity and orbital eccentricity, and has recently (July 2015) been observed by the New Horizons spacecraft. Aims. The main goals of this study are (i) to construct a well calibrated record of the seasonal evolution of surface pressure on Pluto and (ii) to constrain the structure of the lower atmosphere using a central flash observed in 2015. Methods. Eleven stellar occultations by Pluto observed between 2002 and 2016 are used to retrieve atmospheric profiles (density, pressure, temperature) between altitude levels of ~5 and ~380 km (i.e. pressures from ~ 10 μbar to 10 nbar). Results. (i) Pressure has suffered a monotonic increase from 1988 to 2016, that is compared to a seasonal volatile transport model, from which tight constraints on a combination of albedo and emissivity of N2 ice are derived. (ii) A central flash observed on 2015 June 29 is consistent with New Horizons REX profiles, provided that (a) large diurnal temperature variations (not expected by current models) occur over Sputnik Planitia; and/or (b) hazes with tangential optical depth of ~0.3 are present at 4–7 km altitude levels; and/or (c) the nominal REX density values are overestimated by an implausibly large factor of ~20%; and/or (d) higher terrains block part of the flash in the Charon facing hemisphere

Elevated protein concentrations in newborn blood and the risks of autism spectrum disorder, and of social impairment, at age 10 years among infants born before the 28th week of gestation

Among the 1 of 10 children who are born preterm annually in the United States, 6% are born before the third trimester. Among children who survive birth before the 28th week of gestation, the risks of autism spectrum disorder (ASD) and non-autistic social impairment are severalfold higher than in the general population. We examined the relationship between top quartile inflammation-related protein concentrations among children born extremely preterm and ASD or, separately, a high score on the Social Responsiveness Scale (SRS total score ≥65) among those who did not meet ASD criteria, using information only from the subset of children whose DAS-II verbal or non-verbal IQ was ≥70, who were assessed for ASD, and who had proteins measured in blood collected on ≥2 days (N = 763). ASD (N = 36) assessed at age 10 years is associated with recurrent top quartile concentrations of inflammation-related proteins during the first post-natal month (e.g., SAA odds ratio (OR); 95% confidence interval (CI): 2.5; 1.2–5.3) and IL-6 (OR; 95% CI: 2.6; 1.03–6.4)). Top quartile concentrations of neurotrophic proteins appear to moderate the increased risk of ASD associated with repeated top quartile concentrations of inflammation-related proteins. High (top quartile) concentrations of SAA are associated with elevated risk of ASD (2.8; 1.2–6.7) when Ang-1 concentrations are below the top quartile, but not when Ang-1 concentrations are high (1.3; 0.3–5.8). Similarly, high concentrations of TNF-α are associated with heightened risk of SRS-defined social impairment (N = 130) (2.0; 1.1–3.8) when ANG-1 concentrations are not high, but not when ANG-1 concentrations are elevated (0.5; 0.1–4.2)