A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution

We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up to two orders of magnitude more x-ray photons than in previous schemes based on the use of kHz lasers. Consequently, we demonstrate an order of magnitude increase in the signal-to-noise of time-resolved XAS of molecular systems in solution. This makes it possible to investigate highly dilute samples at concentrations approaching physiological conditions for biological systems. The simplicity and compactness of the scheme allows for straightforward implementation at any synchrotron beamline and for a wide range of x-ray probe techniques, such as time-resolved diffraction or x-ray emission studies.     

Active load with cross-coupled bulk for high-gain high-CMRR nanometer CMOS differential stages

Nanometer CMOS technologies are characterized by low intrinsic gain and limited rejection to common-mode disturbances, issues that analog designers must counteract through nonconventional circuit solutions able to operate under sub–1-V supply voltages. In this letter, an approach originally proposed as a common-mode control loop for body-driven amplifiers is exploited by cross-connecting the bulk terminals of the active-load transistors of a source-coupled pair to sensibly improve its small-signal performance. A design example in 65-nm process supplied from 750 mV shows that the presented solution offers both a nominal 20-dB increase in differential gain and 29-dB increase in CMRR, as compared with the standard counterpart.     

Selective attention to affective stimuli and clinical depression among youths: Role of anxiety and specificity of emotion.

Cognitive models of psychopathology posit that the content or focus of information-processing biases (e.g., attentional biases) is disorder specific: Depression is hypothesized to be characterized by attentional biases specifically for depression-relevant stimuli (e.g., sad facial expressions), whereas anxiety should relate particularly to attentional biases to threat-relevant stimuli (e.g., angry faces). However, little research has investigated this specificity hypothesis and none with a sample of youths. The present study examined attentional biases to emotional faces (sad, angry, and happy compared with neutral) in groups of pure depressed, pure anxious, comorbid depressed and anxious, and control youths (ages 9–17 years; N = 161). Consistent with cognitive models, pure depressed and pure anxious youths exhibited attentional biases specifically to sad and angry faces, respectively, whereas comorbid youths exhibited attentional biases to both facial expressions. In addition, control youths exhibited attentional avoidance of sad faces, and comorbid boys avoided happy faces. Overall, findings suggest that cognitive biases and processing of particular emotional information are specific to pure clinical depression and anxiety, and results inform etiological models of potentially specific processes that are associated with internalizing disorders among youths. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potential dosemeter for quantifying biologically effective blue light exposures

This paper reports on the development of a blue light (VIS(BL)) dosemeter. The VIS(BL) dosemeter is based on the combination of polysulfone and phenothiazine as a potential VIS(BL) dosemeter for population studies of exposures related to the blue light hazard. This research found that this combination of photosensitive chromophores reacts to both ultraviolet and visible wavelengths of the solar spectrum. Further to this, the majority of the ultraviolet wavelengths <380 nm can be filtered out with the use of a low-pass filter. It was found that a large change in optical absorbance at 437 nm occurred when the dosemeter was employed to quantify the solar blue light hazard exposures. Preliminary results indicate that this dosemeter saturates relatively slowly and is able to measure exposures equivalent to >1200 kJ m(-2) of blue light hazard weighted solar radiation.     

Editorial

Computing and Visualization in Science -     

One-dimensional models for blood flow in arteries

In this paper a family of one-dimensional nonlinear systems which model the blood pulse propagation in compliant arteries is presented and investigated. They are obtained by averaging the Navier-Stokes equation on each section of an arterial vessel and using simplified models for the vessel compliance. Different differential operators arise depending on the simplifications made on the structural model. Starting from the most basic assumption of pure elastic instantaneous equilibrium, which provides a well-known algebraic relation between intramural pressure and vessel section area, we analyse in turn the effects of terms accounting for inertia, longitudinal pre-stress and viscoelasticity. The problem of how to account for branching and possible discontinuous wall properties is addressed, the latter aspect being relevant in the presence of prosthesis and stents. To this purpose a domain decomposition approach is adopted and the conditions which ensure the stability of the coupling are provided. The numerical method here used in order to carry out several test cases for the assessment of the proposed models is based on a finite element Taylor-Galerkin scheme combined with operator splitting techniques.     

CMOS current‐steering DAC architectures based on the triple‐tail cell

In this paper two novel current‐steering digital‐to‐analog converter (DAC) architectures, exploiting the triple‐tail cell as switching element, are presented. The proposed solutions are theoretically analysed and design equations are carried out. The two architectures show better performance than the classical binary‐weighted solution and it is shown that they can profitably substitute the binary sub‐DAC section in a segmented topology. Theoretical results are compared with behavioural‐level simulations and confirm the effectiveness of the proposed architectures. Copyright © 2007 John Wiley & Sons, Ltd.     

Gender Differences in Diabetic Kidney Disease: Focus on Hormonal,Genetic and Clinical Factors

Diabetic kidney disease (DKD) is one of the most serious complications of both type 1 (T1DM) and type 2 diabetes mellitus (T2DM). Current guidelines recommend a personalized approach in order to reduce the burden of DM and its complications. Recognizing sex and gender- differences in medicine is considered one of the first steps toward personalized medicine, but the gender issue in DM has been scarcely explored so far. Gender differences have been reported in the incidence and the prevalence of DKD, in its phenotypes and clinical manifestations, as well as in several risk factors, with a different impact in the two genders. Hormonal factors, especially estrogen loss, play a significant role in explaining these differences. Additionally, the impact of sex chromosomes as well as the influence of gene–sex interactions with several susceptibility genes for DKD have been investigated. In spite of the increasing evidence that sex and gender should be included in the evaluation of DKD, several open issues remain uncovered, including the potentially different effects of newly recommended drugs, such as SGLT2i and GLP1Ras. This narrative review explored current evidence on sex/gender differences in DKD, taking into account hormonal, genetic and clinical factors.     

Comparison Between Reduced Basis and Stochastic Collocation Methods for Elliptic Problems

The stochastic collocation method (Babu?ka et al. in SIAM J Numer Anal 45(3):1005–1034, 2007; Nobile et al. in SIAM J Numer Anal 46(5):2411–2442, 2008a; SIAM J Numer Anal 46(5):2309–2345, 2008b; Xiu and Hesthaven in SIAM J Sci Comput 27(3):1118–1139, 2005) has recently been applied to stochastic problems that can be transformed into parametric systems. Meanwhile, the reduced basis method (Maday et al. in Comptes Rendus Mathematique 335(3):289–294, 2002; Patera and Rozza in Reduced basis approximation and a posteriori error estimation for parametrized partial differential equations Version 1.0. Copyright MIT, http://augustine.mit.edu, 2007; Rozza et al. in Arch Comput Methods Eng 15(3):229–275, 2008), primarily developed for solving parametric systems, has been recently used to deal with stochastic problems (Boyaval et al. in Comput Methods Appl Mech Eng 198(41–44):3187–3206, 2009; Arch Comput Methods Eng 17:435–454, 2010). In this work, we aim at comparing the performance of the two methods when applied to the solution of linear stochastic elliptic problems. Two important comparison criteria are considered: (1), convergence results of the approximation error; (2), computational costs for both offline construction and online evaluation. Numerical experiments are performed for problems from low dimensions $O(1)$ to moderate dimensions $O(10)$ and to high dimensions $O(100)$ . The main result stemming from our comparison is that the reduced basis method converges better in theory and faster in practice than the stochastic collocation method for smooth problems, and is more suitable for large scale and high dimensional stochastic problems when considering computational costs.