Duality relations for the ASEP conditioned on a low current

We consider the asymmetric simple exclusion process (ASEP) on a finite lattice with periodic boundary conditions, conditioned to carry an atypically low current. For an infinite discrete set of currents, parametrized by the driving strength $s_K$, $K \geq 1$, we prove duality relations which arise from the quantum algebra $U_q[\mathfrak{gl}(2)]$ symmetry of the generator of the process with reflecting boundary conditions. Using these duality relations we prove on microscopic level a travelling-wave property of the conditioned process for a family of shock-antishock measures for $N>K$ particles: If the initial measure is a member of this family with $K$ microscopic shocks at positions $(x_1,\dots,x_K)$, then the measure at any time $t>0$ of the process with driving strength $s_K$ is a convex combination of such measures with shocks at positions $(y_1,\dots,y_K)$. which can be expressed in terms of $K$-particle transition probabilities of the conditioned ASEP with driving strength $s_N$.Comment: 26 page

Status and Potential of Single-cell Transcriptomics for Understanding Plant Development and Functional Biology

Funding Information University of Western Australia Acknowledgments The authors would like to extend sincere thanks to Robert Salomon for inspiring to write this manuscript. Resources were provided by The University of Western Australia.Peer reviewedPostprin

Experimental Modelling of Viscoelastic Self-Heating in Healthy and Degenerate Bovine Intervertebral Discs

Objectives Low back pain (LBP) is an increasing drain on developed economies due to direct medical costs and lost working days. The majority of medical costs can be attributed to long-term problems resulting from specific physiological conditions. Acute injury and/or chronic degeneration of the intervertebral disc (IVD) has been linked with long term pain with high levels of nerve in-growth in degenerate IVDs. The fact that disc degeneration is a structural failing and not just a pathogenesis of pain may lead to reduced mobility and quality of life (QOL). Degenerate IVDs have elevated levels of heat shock proteins (HSPs) and HSPs elevated temperatures and/or heat shock within the IVD is a potential mechanism for HSP upregulation. Is it possible that high temperatures are a precursor to degeneration? Could activities of daily living (ADL) result in elevated temperatures in the IVD? This study aims to determine if there is a significant generation of heat within the IVD when subjected to cyclic loading at levels and frequencies relevant to ADL and whether this is effected by degeneration. Materials and Methods Bovine coccygeal discs were removed whole from tail sections and half of the discs were injected with a 2mg/ml collagenase solution and incubated at 37°C for 2 hours to simulate moderate degeneration. Discs were then subjected to sinusoidal loading at 2Hz at force levels equivalent to those in the human spine during locomotion. Mechanical data was analysed with MATLAB software to determine the energy dissipated by the discs for each cycle of loading and an idealised thermal model was generated to predict temperature change within the disc. Results Under axial loading equivalent to that in the lumbar spine during walking degenerate discs showed greater average compression than healthy discs (0.108mm and 0.024mm respectively) and therefore substantially lower average stiffness (714N/mm and 3149N/mm). Average heat generation in degenerate IVDs (2.79mW) was lower than that in healthy discs (4.13mW). An idealised 3D model of heat loss from the disc showed no significant increase in disc temperature in either healthy or degenerate disc condition. Conclusions Heat generated due to dissipated energy from axial loading of intervertebral discs at loading equivalent to that in the lumbar spine when walking is not enough to induce significant temperature increases within the disc. If elevated levels of HSPs within degenerate discs are the result of high temperatures, heat generated within the disc due to activities of daily living such as walking are not the cause

Material Behaviours of Healthy, Degenerate and Hydrogel Injected Bovine Intervertebral Discs

Objectives Low back pain (LBP) is an increasing drain on developed economies due to direct medical costs and lost working days. The majority of medical costs can be attributed to long-term problems resulting from specific physiological conditions. Acute injury and/or chronic degeneration of the intervertebral disc (IVD) has been linked with long term pain with high levels of nerve in-growth in degenerate IVDs. The fact that disc degeneration is a structural failing and not just a pathogenesis of pain may lead to reduced mobility and quality of life (QOL). Mesenchymal stem cell (MSC) interventions have been proposed as a treatment for degenerate IVDs but little is known about how the injection of a hydrogel matrix required by such interventions affects the material properties of the intervertebral disc and what effects this might have on disc health. This study aims to determine the difference in material behaviours of healthy, degenerate and hydrogel injected IVDs subjected to cyclic loading simulating activities of daily living (ADL). Materials and Methods Bovine coccygeal discs were dissected whole from tail sections and split in to three equal test groups; healthy, degenerate and hydrogel injected. Degenerate and hydrogel injected groups were injected with a 2 mg/ml collagenase solution and incubated at 37°C for 2 hours to simulate moderate degeneration, the hydrogel injected group then received a hydrogel injection. All discs were then subjected to sinusoidal loading at 2Hz at force levels equivalent to those in the human spine during walking and mechanical data analysed to determine respective material behaviours of each group. Results Under axial loading simulating walking in the lumbar spine compression (absolute and relative strain) and stiffness of discs varied across all three test groups. Conclusions Cyclic loading simulating activities of daily living was found to result in different material behaviours in bovine intervertebral discs that were moderately degenerated and/or injected with hydrogel relative to healthy discs

Ultrasound in evaluation of post-interventional femoral vein obstruction: a case report

Ultrasound is the preferred imaging modality in diagnosis of vascular complications following cardiac catheterization and intervention. In some cases, however, bleeding surrounding the femoral vessels, may severely distort the color Doppler images, making detection of venous complications especially difficult. This report refers to such a case where post-catheterization haematoma was suspected to cause an obstruction of the femoral vein. Spectral Doppler recordings of blood flow in the common femoral vein, up-stream, distal to the hemorrhagic area, confirmed the diagnosis of obstruction by demonstrating changes in the venous flow pattern in the common femoral vein, consistent with venous hypertension. Due to the poor quality of the ultrasound images, the exact cause of the obstruction had to be established by another imaging modality, not affected by haemorrhages. CT showed that the common femoral vein was compressed at the puncture site by surrounding haemorrhages. Thus, when bleeding due to cardiac catheterization is associated with possible venous obstruction and findings by color Doppler are equivocal due to degradation of the color-Doppler image, detection of venous hypertension by spectral Doppler, performed distal to the bleeding area, strongly supports the presence of venous obstruction where the exact cause may be established by CT

Sialic Acid Glycobiology Unveils Trypanosoma cruzi Trypomastigote Membrane Physiology.

Trypanosoma cruzi, the flagellate protozoan agent of Chagas disease or American trypanosomiasis, is unable to synthesize sialic acids de novo. Mucins and trans-sialidase (TS) are substrate and enzyme, respectively, of the glycobiological system that scavenges sialic acid from the host in a crucial interplay for T. cruzi life cycle. The acquisition of the sialyl residue allows the parasite to avoid lysis by serum factors and to interact with the host cell. A major drawback to studying the sialylation kinetics and turnover of the trypomastigote glycoconjugates is the difficulty to identify and follow the recently acquired sialyl residues. To tackle this issue, we followed an unnatural sugar approach as bioorthogonal chemical reporters, where the use of azidosialyl residues allowed identifying the acquired sugar. Advanced microscopy techniques, together with biochemical methods, were used to study the trypomastigote membrane from its glycobiological perspective. Main sialyl acceptors were identified as mucins by biochemical procedures and protein markers. Together with determining their shedding and turnover rates, we also report that several membrane proteins, including TS and its substrates, both glycosylphosphatidylinositol-anchored proteins, are separately distributed on parasite surface and contained in different and highly stable membrane microdomains. Notably, labeling for α(1,3)Galactosyl residues only partially colocalize with sialylated mucins, indicating that two species of glycosylated mucins do exist, which are segregated at the parasite surface. Moreover, sialylated mucins were included in lipid-raft-domains, whereas TS molecules are not. The location of the surface-anchored TS resulted too far off as to be capable to sialylate mucins, a role played by the shed TS instead. Phosphatidylinositol-phospholipase-C activity is actually not present in trypomastigotes. Therefore, shedding of TS occurs via microvesicles instead of as a fully soluble form

The cometary composition of a protoplanetary disk as revealed by complex cyanides

Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface, seeding its early chemistry. Unlike asteroids, comets preserve a nearly pristine record of the Solar Nebula composition. The presence of cyanides in comets, including 0.01% of methyl cyanide (CH3CN) with respect to water, is of special interest because of the importance of C-N bonds for abiotic amino acid synthesis. Comet-like compositions of simple and complex volatiles are found in protostars, and can be readily explained by a combination of gas-phase chemistry to form e.g. HCN and an active ice-phase chemistry on grain surfaces that advances complexity[3]. Simple volatiles, including water and HCN, have been detected previously in Solar Nebula analogues - protoplanetary disks around young stars - indicating that they survive disk formation or are reformed in situ. It has been hitherto unclear whether the same holds for more complex organic molecules outside of the Solar Nebula, since recent observations show a dramatic change in the chemistry at the boundary between nascent envelopes and young disks due to accretion shocks[8]. Here we report the detection of CH3CN (and HCN and HC3N) in the protoplanetary disk around the young star MWC 480. We find abundance ratios of these N-bearing organics in the gas-phase similar to comets, which suggests an even higher relative abundance of complex cyanides in the disk ice. This implies that complex organics accompany simpler volatiles in protoplanetary disks, and that the rich organic chemistry of the Solar Nebula was not unique.Comment: Definitive version of the manuscript is published in Nature, 520, 7546, 198, 2015. This is the author's versio

Optical Lattices: Theory

This chapter presents an overview of the properties of a Bose-Einstein condensate (BEC) trapped in a periodic potential. This system has attracted a wide interest in the last years, and a few excellent reviews of the field have already appeared in the literature (see, for instance, [1-3] and references therein). For this reason, and because of the huge amount of published results, we do not pretend here to be comprehensive, but we will be content to provide a flavor of the richness of this subject, together with some useful references. On the other hand, there are good reasons for our effort. Probably, the most significant is that BEC in periodic potentials is a truly interdisciplinary problem, with obvious connections with electrons in crystal lattices, polarons and photons in optical fibers. Moreover, the BEC experimentalists have reached such a high level of accuracy to create in the lab, so to speak, paradigmatic Hamiltonians, which were first introduced as idealized theoretical models to study, among others, dynamical instabilities or quantum phase transitions.Comment: Chapter 13 in Part VIII: "Optical Lattices" of "Emergent Nonlinear Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P. G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer Series on Atomic, Optical, and Plasma Physics, 2007) - pages 247-26

Does a SLAP lesion affect shoulder muscle recruitment as measured by EMG activity during a rugby tackle?

Background: The study objective was to assess the influence of a SLAP lesion on onset of EMG activity in shoulder muscles during a front on rugby football tackle within professional rugby players. Methods: Mixed cross-sectional study evaluating between and within group differences in EMG onset times. Testing was carried out within the physiotherapy department of a university sports medicine clinic. The test group consisted of 7 players with clinically diagnosed SLAP lesions, later verified on arthroscopy. The reference group consisted of 15 uninjured and full time professional rugby players from within the same playing squad. Controlled tackles were performed against a tackle dummy. Onset of EMG activity was assessed from surface EMG of Pectorialis Major, Biceps Brachii, Latissimus Dorsi, Serratus Anterior and Infraspinatus muscles relative to time of impact. Analysis of differences in activation timing between muscles and limbs (injured versus non-injured side and non injured side versus matched reference group). Results: Serratus Anterior was activated prior to all other muscles in all (P = 0.001-0.03) subjects. In the SLAP injured shoulder Biceps was activated later than in the non-injured side. Onset times of all muscles of the noninjured shoulder in the injured player were consistently earlier compared with the reference group. Whereas, within the injured shoulder, all muscle activation timings were later than in the reference group. Conclusions: This study shows that in shoulders with a SLAP lesion there is a trend towards delay in activation time of Biceps and other muscles with the exception of an associated earlier onset of activation of Serratus anterior, possibly due to a coping strategy to protect glenohumeral stability and thoraco-scapular stability. This trend was not statistically significant in all cases