Inclination-dependent spectral and timing properties in transient black hole X-ray binaries

We use a simple one-dimensional parameterisation of timing properties to show that hard and hard-intermediate state transient black hole X-ray binaries with the same power-spectral shape have systematically harder X-ray power-law emission in higher-inclination systems. We also show that the power-spectral shape and amplitude of the broadband noise (with low-frequency quasi-periodic oscillations, QPOs, removed) is independent of inclination, confirming that it is well-correlated with the intrinsic structure of the emitting regions and that the "type C" QPO, which is inclination-dependent, has a different origin to the noise, probably geometric. Our findings suggest that the power-law emission originates in a corona which is flattened in the plane of the disc, and not in a jet-like structure which would lead to softer spectra at higher inclinations. However, there is tentative evidence that the inclination-dependence of spectral shape breaks down deeper into the hard state. This suggests either a change in the coronal geometry and possible evidence for contribution from jet emission, or alternatively an even more optically thin flow in these states.Comment: 6 Pages, 4 Figures, accepted as a Letter by MNRA

Power-Colours: Simple X-ray Binary Variability Comparison

We demonstrate a new method of variability classification using observations of black hole X-ray binaries. Using `power colours' -- ratios of integrated power in different Fourier frequency bands -- we can clearly differentiate different canonical black hole states as the objects evolve during outburst. We analyse (~ 2400) Rossi X-ray Timing Explorer observations of 12 transient low mass black hole X-ray binaries and find that the path taken around the power colour-colour diagram as the sources evolve is highly consistent from object to object. We discuss how the consistency observed in the power colour-colour diagram between different objects allows for easy state classification based on only a few observations, and show how the power-spectral shapes can be simply classified using a single parameter, the power-spectral `hue'. To illustrate the benefits of our simple model-independent approach, we show that the persistent high mass X-ray binary Cyg X-1 shows very similar power-spectral evolution to the transient black hole sources, with the main difference being caused by a combination of a lack of quasi-periodic oscillations and an excess of low-frequency power-law noise in the Cyg X-1 power spectra during the transitional state. We also compare the transient objects to the neutron star atoll source Aquila X-1, demonstrating that it traces a different path in the power colour-colour plot. Thus, power-colours could be an effective method to classify newly discovered X-ray binaries.Comment: 13 pages, 9 figures, accepted by MNRA

Xenogeneic, extracorporeal liver perfusion in primates improves the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio)

In fulminant hepatic failure (FHF), the development of hepatic encephalopathy is associated with grossly abnormal concentrations of plasma amino acids (PAA). Normalization of the ratio of branched-chain amino acids to aromatic amino acids (Fischer's ratio) correlates with clinical improvement. This study evaluated changes in PAA metabolism during 4 h of isolated, normothermic extracorporeal liver perfusion using a newly designed system containing human blood and a rhesus monkey liver. Bile and urea production were within the physiological range. Release of the transaminases AST, ALT and LDH were minimal. The ratio of branched (valine, leucine, isoleucine) to aromatic (tyrosine, phenylalanine) amino acids increased significantly. These results indicate that a xenogeneic extracorporeal liver perfusion system is capable of significantly increasing Fischer's ratio and may play a role in treating and bridging patients in FHF in the future

Ultrasensitive 3He magnetometer for measurements of high magnetic fields

We describe a 3He magnetometer capable to measure high magnetic fields (B > 0.1 Tesla) with a relative accuracy of better than 10^-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2* being of order minutes which is achieved for spherical sample cells in the regime of motional narrowing where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in-situ using a new, non-standard variant of the metastability exchange optical pumping. We show that miniaturization helps to increase T2* further and that the measurement sensitivity is not significantly affected by temporal field fluctuations of order 10^-4.Comment: 27 pages, 7 figure

The psychophysics of absolute threshold and signal duration: A probabilistic approach

The absolute threshold for a tone depends on its duration; longer tones have lower thresholds. This effect has traditionally been explained in terms of ?temporal integration? involving the summation of energy or perceptual information over time. An alternative probabilistic explanation of the process is formulated in terms of simple equations that predict not only the time=duration dependence but also the shape of the psychometric function at absolute threshold. It also predicts a tight relationship between these two functions. Measurements made using listeners with either normal or impaired hearing show that the probabilistic equations adequately fit observed threshold-duration functions and psychometric functions. The mathematical formulation implies that absolute threshold can be construed as a two-valued function: (a) gain and (b) sensory threshold, and both parameters can be estimated from threshold-duration data. Sensorineural hearing impairment is sometimes associated with a smaller threshold=duration effect and sometimes with steeper psychometric functions. The equations explain why these two effects are expected to be linked. The probabilistic approach has the potential to discriminate between hearing deficits involving gain reduction and those resulting from a raised sensory threshold

The Ubiquity of the rms-flux relation in Black Hole X-ray Binaries

We have investigated the short term linear relation between the rms variability and the flux in 1,961 observations of 9 black hole X-ray binaries. The rms-flux relation for the 1-10 Hz range is ubiquitously observed in any observation with good variability signal to noise (> 3 % 1-10 Hz fractional rms). This concurs with results from a previous study of Cygnus X-1 (Gleissner et. al. 2004), and extends detection of the rms-flux relation to a wider range of states. We find a strong dependence of the flux intercept of the rms-flux relation on source state; as the source transitions from the hard state into the hard intermediate state the intercept becomes strongly positive. We find little evidence for flux dependence of the broad-band noise within the PSD shape, excepting a small subset of observations from one object in an anomalous soft-state. We speculate that the ubiquitous linear rms-flux relation in the broad band noise of this sample, representing a range of different states and objects, indicates that its formation mechanism is an essential property of the luminous accretion flow around black holes.Comment: 12 pages, 6 figures, accepted for publication in MNRA

Modelling and simulation of fluid-structure interactions in human snoring

Snoring noise is generated by vibration of the soft tissues of the upper airway, principally those that form the back of the roof of the mouth (the soft palate) and its conical extension (the uvula). In addition to discord with bed partners, snorers are at much greater risk of obstructive sleep apnoea. This sleep-related breathing disorder is characterised by episodic upper airway obstruction with accompanying sleep disruption and consequent excessive daytime sleepiness, as well as an elevated risk of accidents and cardiovascular disease. The instability that leads to flow-induced oscillations characteristic of inspiratory snoring in the human upper airway may be modelled using a cantilevered flexible plate in a mean channel flow. However, the cantilever in existing models strictly only captures the dynamics of the uvula. In a more complete model, these dynamics will be augmented by their interaction with the motions of the soft palate—itself a flexible structure of higher effective stiffness—from which the uvula extends. To investigate how the elasticity of the soft palate affects uvula motion and their combined susceptibility to flow-induced oscillation a modification is made to the standard model. In a one-dimensional cantilevered flexible plate we allow thickness to vary as a function of length, thus effecting local changes in inertia and flexural rigidity.The overall cantilever therefore comprises a section representing the soft palate followed by a section of lower thickness that represents the uvula. The cantilever is attached to a rigid wall (hard palate) separating upper (nasal) and lower (oral) inlets of a rigid-walled channel (pharynx) conveying a viscous flow. This model is formulated using the open-source finite-element software library oomph-lib. A parametric study is performed in which the uvula-to-soft palate length and thickness ratios are varied whilst keeping their combined length constant. Results show that there is a critical uvula-length fraction that determines whether the uvula stabilises or destabilises the system. A relatively ‘short’ uvula swings out of phase with the soft palate and these oscillations are observed to decay; the mode shapes involved are not predicted by a uniform-thickness plate model. By contrast, if the uvula is relatively ‘long’ the flexible plate motion is isolated to the uvular section and the oscillations grow in amplitude, indicating a net energy transfer from fluid to structure. Increasing the thickness, hence inertia and flexural rigidity, of a ‘short’ uvula, e.g., by oedema, makes the fluid-structure system more unstable. In this case if the oedema were aggrevated by the vibratory mechanical insult then it would be self-sustaining and imply a bidirectional relationship between snoring and oedema of the uvula.Anatomical variability is common in the lengths of the soft palate and uvula which may make some people more susceptible than others to uvulopalatal snoring. Palatal surgery for snoring has proved highly variable in its effectiveness. Modelling of palatal motion using this approach may help guide patient selection for and type of soft-palate surgery applied to treat this common and potentially disabling condition

Chemical vapor deposition of highly conjugated, transparent boron carbon nitride thin films

Ternary materials made up only from the lightweight elements boron, carbon, and nitrogen are very attractive due to their tunable properties that can be obtained by changing the relative elemental composition. However, most of the times, the synthesis requires to use up to three different precursor and very high temperatures for the synthesis. Moreover, the low reciprocal solubility of boron nitride and graphene often leads to BN-C composite materials due to phase segregation. Herein, an innovative method is presented to prepare BCN thin films by chemical vapor deposition from a single source precursor, melamine diborate. The deposition occurs homogenously at relatively low temperatures generating very high degree of sp2 conjugation. The as-prepared thin films possess high transparency and refractive index values in the visible range that are of interest for reflective mirrors and lenses. Furthermore, they are wide-bandgap semiconductor with very positive valence band, making these materials very stable against oxidation of interest as protective coating and charge transport layer for solar cells. The simple chemical vapor deposition method that relies on commonly available and low-hazard precursor can open the way for application of BCN thin films in optics, optoelectronics, and beyond

Zwei Jahre pro-Q – Bilanz eines biokonformen Eutergesundheitsprogrammes

The pro-q-project is an udder health programme especially for organic farmers under Swiss conditions. The aim is to minimize the use of s antibiotics and to assure a good udder health state on the farms. At the end of the third project year of 100 project farms 16 participate for more than two years. The udder health situation of these 16 farms improved moderately in the second project year (37% of the cows with a so-matic cell count > 100’000/ml) compared to the year before project start (40% of the cows with a somatic cell count > 100’000/ml). Furthermore, a nearly linear increase of the arithmetic mean of herd lactation number (3.27 year before project start, 3.33 first project year, 3.44 second project year, resp.) could be found. The number of antibiotic treatments per cow and year decreased from 0.37 in the year before project start to 0.24 in the second project year