Affine maps of density matrices

For quantum systems described by finite matrices, linear and affine maps of matrices are shown to provide equivalent descriptions of evolution of density matrices for a subsystem caused by unitary Hamiltonian evolution in a larger system; an affine map can be replaced by a linear map, and a linear map can be replaced by an affine map. There may be significant advantage in using an affine map. The linear map is generally not completely positive, but the linear part of an equivalent affine map can be chosen to be completely positive and related in the simplest possible way to the unitary Hamiltonian evolution in the larger system.Comment: 4 pages, title changed, sentence added, reference update

Nonlinear projective filtering in a data stream

We introduce a modified algorithm to perform nonlinear filtering of a time series by locally linear phase space projections. Unlike previous implementations, the algorithm can be used not only for a posteriori processing but includes the possibility to perform real time filtering in a data stream. The data base that represents the phase space structure generated by the data is updated dynamically. This also allows filtering of non-stationary signals and dynamic parameter adjustment. We discuss exemplary applications, including the real time extraction of the fetal electrocardiogram from abdominal recordings.Comment: 8 page

The human myometrium differentially expresses mTOR signalling components before and during pregnancy: Evidence for regulation by progesterone

Emerging studies implicate the signalling of the mammalian target of rapamycin (mTOR) in a number of reproductive functions. To this date, there are no data regarding the expression of mTOR signalling components in the human myometrium during pregnancy. We hypothesized that mTOR-related genes might be differentially expressed in term or preterm labour as well as in labour or non-labour myometria during pregnancy. Using quantitative RT-PCR we demonstrate for first time that there is a significant downregulation of mTOR, DEPTOR, and Raptor in preterm labouring myometria when compared to non-pregnant tissues taken from the same area (lower segment). We used an immortalized myometrial cell line (ULTR) as an in vitro model to dissect further mTOR signalling. In ULTR cells DEPTOR and Rictor had a cytoplasmic distribution, whereas mTOR and Raptor were detected in the cytoplasm and the nucleus, indicative of mTORC1 shuttling. Treatment with inflammatory cytokines caused only minor changes in gene expression of these components, whereas progesterone caused significant down-regulation. We performed a non-biased gene expression analysis of ULTR cells using Nimblegen human gene expression microarray (n = 3), and selected genes were validated by quantitative RT-PCR in progesterone treated myometrial cells. Progesterone significantly down-regulated key components of the mTOR pathway. We conclude that the human myometrium differentially expresses mTOR signalling components and they can be regulated by progesterone. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.This research was funded by National Institutes of Health Grant ESO12961

Prospective relationships between body weight and physical activity: an observational analysis from the NAVIGATOR study

Objectives: While bidirectional relationships exist between body weight and physical activity, direction of causality remains uncertain and previous studies have been limited by self-reported activity or weight and small sample size. We investigated the prospective relationships between weight and physical activity. Design: Observational analysis of data from the Nateglinide And Valsartan in Impaired Glucose Tolerance Outcomes Research (NAVIGATOR) study, a double-blinded randomised clinical trial of nateglinide and valsartan, respectively. Setting Multinational study of 9306 participants. Participants: Participants with biochemically confirmed impaired glucose tolerance had annual measurements of both weight and step count using research grade pedometers, worn for 7 days consecutively. Along with randomisation to valsartan or placebo plus nateglinide or placebo, participants took part in a lifestyle modification programme. Outcome measures: Longitudinal regression using weight as response value and physical activity as predictor value was conducted, adjusted for baseline covariates. Analysis was then repeated with physical activity as response value and weight as predictor value. Only participants with a response value preceded by at least three annual response values were included. Results: Adequate data were available for 2811 (30%) of NAVIGATOR participants. Previous weight (χ2=16.8; p<0.0001), but not change in weight (χ2=0.1; p=0.71) was inversely associated with subsequent step count, indicating lower subsequent levels of physical activity in heavier individuals. Change in step count (χ2=5.9; p=0.02) but not previous step count (χ2=0.9; p=0.34) was inversely associated with subsequent weight. However, in the context of trajectories already established for weight (χ2 for previous weight measurements 747.3; p<0.0001) and physical activity (χ2 for previous step count 432.6; p<0.0001), these effects were of limited clinical importance. Conclusions: While a prospective bidirectional relationship was observed between weight and physical activity, the magnitude of any effect was very small in the context of natural trajectories already established for these variables

(l1,l2)-RIP and Projected Back-Projection Reconstruction for Phase-Only Measurements

This letter analyzes the performances of a simple reconstruction method, namely the Projected Back-Projection (PBP), for estimating the direction of a sparse signal from its phase-only (or amplitude-less) complex Gaussian random measurements, i.e., an extension of one-bit compressive sensing to the complex field. To study the performances of this algorithm, we show that complex Gaussian random matrices respect, with high probability, a variant of the Restricted Isometry Property (RIP) relating to the l1 -norm of the sparse signal measurements to their l2 -norm. This property allows us to upper-bound the reconstruction error of PBP in the presence of phase noise. Monte Carlo simulations are performed to highlight the performance of our approach in this phase-only acquisition model when compared to error achieved by PBP in classical compressive sensing.Comment: 4 pages, 2 figure

Tuning the interactions between electron spins in fullerene-based triad systems

A series of six fullerene-linker-fullerene triads have been prepared by the stepwise addition of the fullerene cages to bridging moieties thus allowing the systematic variation of fullerene cage (C60 or C70) and linker (oxalate or terephthalate) and enabling precise control over the inter-fullerene separation. The fullerene triads exhibit good solubility in common organic solvents, have linear geometries and are diastereomerically pure. Cyclic voltammetric measurements demonstrate the excellent electron accepting capacity of all triads, with up to 6 electrons taken up per molecule in the potential range between -2.3 and 0.2 V (vs. Fc+/Fc). No significant electronic interactions between fullerene cages are observed in the ground state indicating that the individual properties of each C60 or C70 cage are retained within the triads. The electron-electron interactions in the electrochemically generated dianions of these triads, with one electron per fullerene cage were studied by EPR spectroscopy. The nature of electron-electron coupling observed at 77 K can be described as an equilibrium between a doublet and triplet state biradical which depends on the interfullerene spacing. The shorter oxalate-bridged triads exhibit stronger spin-spin coupling with triplet character, while in the longer terephthalate-bridged triads the intramolecular spin-spin coupling is significantly reduced

Artificial light at night alters predation on colour-polymorphic camouflaged prey

Artificial light at night (ALAN) disrupts biological processes across taxa and at all levels of organisation. Despite growing interest in this globally pervasive sensory pollutant, its impact on colour-guided processes remains largely unexplored. This is especially concerning given the rapid transition in recent years away from narrow-spectrum lighting and towards broad-spectrum options such as white LEDs, which are rich in the short wavelengths of light to which many taxa are particularly sensitive. Camouflage is particularly likely to be disrupted by broader spectra of ALAN due to changes in conspicuousness in background matching prey, which may alter prey recognition in visually guided predators. We simulated natural intensities of moonlight with and without ALAN, using both broad-spectrum (‘white’) ALAN and ALAN filtered to remove the characteristic short (blue) wavelength peak of broad-spectrum LEDs to test whether filtering might mitigate their effects. We tested how exposure to these light treatments impacted predator-prey interactions, using the intertidal crab Carcinus maenas and contrasting colour morphs of the colour-polymorphic snail Littorina obtusata as a model system. Exposure to broad-spectrum ALAN reduced overall predation and reversed the pattern of colour-based prey selection observed under control conditions. Snails were 55% less likely to be attacked under broad-spectrum ALAN than in control conditions, with likelihood decreasing over 70% for yellow snails. Yellow snails were over 26% more likely to be attacked than brown ones under control conditions, but brown snails were over 40% more likely to be attacked than yellow ones under broad-spectrum ALAN. Exposure to filtered ALAN removed any significant colour-based difference in prey recognition. Our results demonstrate that spectral composition is a crucial aspect of ALAN as a sensory pollutant, capable of instigating profound changes in predator-prey interactions that could drive changes in population demography and increase morphological homogeneity in species that depend on colour polymorphism for camouflage

Student Perceptions Of Appropriate Classroom Policies Of College Professors

Student perceptions of classroom management practices and policies employed by college educators have not been widely studied.  Faculty have broad discretion to determine classroom management practices and policies, and faculty are generally evaluated at least annually with student evaluations of teaching as a significant component of  the evaluative process.  The focus of this paper is whether students perceive faculty as having the freedom or discretion to adopt specified behaviors or policies unrelated to course content decisions.&nbsp

Atmospheric extinction coefficients in the Ic\mathrm{I_c} band for several major international observatories: Results from the BiSON telescopes, 1984 to 2016

Over 30 years of solar data have been acquired by the Birmingham Solar Oscillations Network (BiSON), an international network of telescopes used to study oscillations of the Sun. Five of the six BiSON telescopes are located at major observatories. The observational sites are, in order of increasing longitude: Mount Wilson (Hale) Observatory (MWO), California, USA; Las Campanas Observatory (LCO), Chile; Observatorio del Teide, Iza\~{n}a, Tenerife, Canary Islands; the South African Astronomical Observatory (SAAO), Sutherland, South Africa; Carnarvon, Western Australia; and the Paul Wild Observatory, Narrabri, New South Wales, Australia. The BiSON data may be used to measure atmospheric extinction coefficients in the $\mathrm{I_c}$ band (approximately 700-900 nm), and presented here are the derived atmospheric extinction coefficients from each site over the years 1984 to 2016.Comment: 15 pages, 10 figures, 4 tables. Accepted by Astronomical Journal: 2017 July 2

The Initial Mass Function of the Stellar Association NGC 602 in the Small Magellanic Cloud with Hubble Space Telescope ACS Observations

We present our photometric study of the stellar association NGC 602 in the wing of the Small Magellanic Cloud (SMC). The data were taken in the filters F555W and F814W using the Advanced Camera for Surveys (ACS) on-board the Hubble Space Telescope (HST). Photometry was performed using the ACS module of the stellar photometry package DOLPHOT. We detected more than 5,500 stars with a magnitude range of 14 \lsim m_{555} \lsim 28 mag. Three prominent stellar concentrations are identified with star counts in the observed field, the association NGC 602 itself, and two clusters, one of them not being currently in any known catalog. The Color-Magnitude Diagrams (CMDs) of both clusters show features typical for young open clusters, while that of the association reveals bright main sequence (MS) and faint pre-main sequence (PMS) stars as the members of the system. We construct the initial mass spectrum (IMS) of the association by applying an age-independent method of counting the PMS stars within evolutionary tracks, while for the bright MS stars we transform their magnitudes to masses with the use of mass-luminosity relations. The IMS of NGC 602 is found to be well represented by a single-power law, corresponding to an Initial Mass Function (IMF) of slope \Gamma\approx -1.2 for 1 \lsim M/M{\solar} \lsim 45. This indicates that the shape of the IMF of a star forming system in the SMC for stars with masses higher than 1 M{\solar} seems to be quite similar to the field IMF in the solar neighborhood.Comment: Accepted for publication in ApJ, 13 pages, 14 figures, emulateapj.cls LaTeX style, full resolution version available on http://www.astro.uni-bonn.de/~dgoulier/Science/NGC602/ms.pd