The fluctuation theorem and Lyapunov weights

The Fluctuation Theorem (FT) is a generalisation of the Second Law of Thermodynamics that applies to small systems observed for short times. For thermostatted systems it gives the probability ratio that entropy will be consumed rather than produced. In this paper we derive the Transient and Steady State Fluctuation Theorems using Lyapunov weights rather than the usual Gibbs weights. At long times the Fluctuation Theorems so derived are identical to those derived using the more standard Gibbs weights.Comment: 26 pages; to appear in Physica

New Velocity Distribution in the Context of the Eddington Theory

Exotic dark matter together with the vacuum energy (associated with the cosmological constant) seem to dominate the Universe. Thus its direct detection is central to particle physics and cosmology. Supersymmetry provides a natural dark matter candidate, the lightest supersymmetric particle (LSP). One essential ingredient in obtaining the direct detection rates is the density and velocity distribution of the LSP. The detection rate is proportional to this density in our vicinity. Furthermore, since this rate is expected to be very low, one should explore the two characteristic signatures of the process, namely the modulation effect, i.e. the dependence of the event rate on the Earth's motion and the correlation of the directional rate with the motion of the sun. Both of these crucially depend on the LSP velocity distribution. In the present paper we study simultaneously density profiles and velocity distributions based on the Eddington theory.Comment: 40 LaTex pages, 19 figures and one table. The previous version was expanded to include new numerical solutions to Poisson's equation. Sheduled to appear in vol. 588, ApJ, May 1, 300

Elemental fingerprinting of Hypericum perforatum (St John's Wort) herb and preparations using ICP-OES and chemometrics

This is a pre-copyedited, author-produced PDF of an article accepted for publication in Journal of Pharmaceutical and Biomedical Analysis following peer review. The version of record [Journal of Pharmaceutical and Biomedical Analysis (June 2016) Vol 125 pp 15-21, first published online March 4, 2016] is available online at doi: http://dx.doi.org/10.1016/j.jpba.2016.02.054 © 2016 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/St. John's wort (SJW) (Hypericum perforatum) is a herbal remedy commonly used to treat mild depression. The elemental profiles of 54 samples (i.e., dry herbs, tablets and capsules) were evaluated by monitoring 25 elements using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The major elemental constituents in the SJW samples were Ca (300-199,000 μg/g), Mg (410-3,530 μg/g), Al (4.4-900 μg/g), Fe (1.154-760 μg/g), Mn (2.4-261 μg/g), Sr (0.88-83.6 μg/g), and Zn (7-64 μg/g). For the sixteen elements that could be reliably quantified, principal component analysis (PCA) was used to investigate underlying patterns in the data. PCA models identified 7 key elements (i.e., Ba, Ca, Cd, Mg, Mo, Ni and Y), which described 85% of the variance in the dataset in the first three principal components. The PCA approach resulted in a general delineation between the three different formulations and provides a basis for monitoring product quality in this manner.Peer reviewe

TLR-mediated activation of Waldenström macroglobulinemia B cells reveals an uncoupling from plasma cell differentiation

Waldenstr¨om macroglobulinemia (WM) is a rare malignancy in which clonal B cells infiltrate the bone marrow and give rise to a smaller compartment of neoplastic plasma cells that secrete monoclonal immunoglobulin M paraprotein. Recent studies into underlying mutations in WM have enabled a much greater insight into the pathogenesis of this lymphoma. However, there is considerably less characterization of the way in which WM B cells differentiate and how they respond to immune stimuli. In this study, we assess WM B-cell differentiation using an established in vitro model system. Using T-cell–dependent conditions, we obtained CD1381 plasma cells from WM samples with a frequency similar to experiments performed with B cells from normal donors. Unexpectedly, a proportion of the WM B cells failed to upregulate CD38, a surface marker that is normally associated with plasmablast transition and maintained as the cells proceed with differentiation. In normal B cells, concomitant Toll-like receptor 7 (TLR7) activation and B-cell receptor cross-linking drives proliferation, followed by differentiation at similar efficiency to CD40-mediated stimulation. In contrast, we found that, upon stimulation with TLR7 agonist R848, WM B cells failed to execute the appropriate changes in transcriptional regulators, identifying an uncoupling of TLR signaling from the plasma cell differentiation program. Provision of CD40L was sufficient to overcome this defect. Thus, the limited clonotypic WM plasma cell differentiation observed in vivo may result from a strict requirement for integrated activation

Homogeneous shear flow of a hard-sphere fluid: Analytic solutions

Recently, a solution for collision-free trajectories in an N particle thermostatted hard-sphere system undergoing homogeneous shear (the so-called "Sllod" equations of motion) led to a kinetic theory of dilute hard-sphere gases under shear. However, a solution for collisions, necessary for a complete theory at higher densities, has been missing. We present an analytic solution to this problem, which provides surprising insights into the mechanical aspects of thermostatting a system in an external field. The equivalence of constant temperature and constant energy ensembles in the thermodynamic limit in equilibrium, the conditions for the nature of heat exchange with the environment (entropy creation and reduction) in the system, and the condition for appearance of the artificial string phase follow from our solution

X-Atlas: An Online Archive of Chandra's Stellar High Energy Transmission Gratings Observations

The high-resolution X-ray spectroscopy made possible by the 1999 deployment of the Chandra X-ray Observatory has revolutionized our understanding of stellar X-ray emission. Many puzzles remain, though, particularly regarding the mechanisms of X-ray emission from OB stars. Although numerous individual stars have been observed in high-resolution, realizing the full scientific potential of these observations will necessitate studying the high-resolution Chandra dataset as a whole. To facilitate the rapid comparison and characterization of stellar spectra, we have compiled a uniformly processed database of all stars observed with the Chandra High Energy Transmission Grating (HETG). This database, known as X-Atlas, is accessible through a web interface with searching, data retrieval, and interactive plotting capabilities. For each target, X-Atlas also features predictions of the low-resolution ACIS spectra convolved from the HETG data for comparison with stellar sources in archival ACIS images. Preliminary analyses of the hardness ratios, quantiles, and spectral fits derived from the predicted ACIS spectra reveal systematic differences between the high-mass and low-mass stars in the atlas and offer evidence for at least two distinct classes of high-mass stars. A high degree of X-ray variability is also seen in both high and low-mass stars, including Capella, long thought to exhibit minimal variability. X-Atlas contains over 130 observations of approximately 25 high-mass stars and 40 low-mass stars and will be updated as additional stellar HETG observations become public. The atlas has recently expanded to non-stellar point sources, and Low Energy Transmission Grating (LETG) observations are currently being added as well

The clearing of discs around late type T Tauri stars: constraints from the infrared two colour plane

We have undertaken SED modeling of discs around low mass T Tauri stars in order to delineate regions of the infrared two colour plane (K - [8] versus K - [24]) that correspond to discs in different evolutionary stages. This provides a ready tool for classifying the nature of star-disc systems based on infrared photometry. In particular we demonstrate the distinct loci followed by discs that undergo `uniform draining' (reduction in surface density by a spatially uniform factor) from those that clear from the inside out. We draw attention to the absence of objects on this `draining locus' in those star forming regions where the 24um sensitivity would permit their detection, as compared with the ~20 objects in these regions with colours suggestive of inner holes. We thus conclude that discs predominantly clear from the inside out. We also apply our classification of the infrared two colour plane to stars of spectral type M3-M5 in the IC 348 cluster and show that some of its members (dubbed `weak excess' sources by Muzerolle et al 2010) that had previously been assumed to be in a state of clearing are instead likely to be optically thick discs in which the dust is well settled towards the mid-plane. Nevertheless, there are many discs in a state of partial clearing in IC 348, with their abundance (relative to the total population of disc bearing stars) being around four times higher than for comparable stars in Taurus. However, the number of partially cleared discs relative to the total number of late type stars is similarly low in both regions (10 and 20 % respectively). We therefore conclude that IC 348 represents a more evolved version of the Taurus population (with more of its discs being highly settled or partially cleared) but that the timescale for clearing is similarly short (a few times 10^5 years) in both cases.Comment: 9 pages, 6 figures, accepted, MNRA