A Distributed and Incremental SVD Algorithm for Agglomerative Data Analysis on Large Networks

In this paper, we show that the SVD of a matrix can be constructed efficiently in a hierarchical approach. Our algorithm is proven to recover the singular values and left singular vectors if the rank of the input matrix $A$ is known. Further, the hierarchical algorithm can be used to recover the $d$ largest singular values and left singular vectors with bounded error. We also show that the proposed method is stable with respect to roundoff errors or corruption of the original matrix entries. Numerical experiments validate the proposed algorithms and parallel cost analysis

Phase coherence and the Nernst effect at magic angles in organic conductors

A giant Nernst signal was recently observed for fields near crystallographic directions in (TMTSF)$_2$PF$_6$. Such large Nernst signals are most naturally associated with the motion of pancake vortices. We propose a model in which phase coherence is destroyed throughout the sample except in planes closely aligned with the applied field $\bf H$. A small tilt above or below the plane changes the direction and density of the penetrating vortices and leads to a Nernst signal that varies with the tilt angle of $\bf H$ as observed. The resistance notches at magic angles are understood in terms of flux-flow dissipation from field-induced vortices.Comment: 4 pages, 4 figure

Empires and Percolation: Stochastic Merging of Adjacent Regions

We introduce a stochastic model in which adjacent planar regions $A, B$ merge stochastically at some rate $\lambda(A,B)$, and observe analogies with the well-studied topics of mean-field coagulation and of bond percolation. Do infinite regions appear in finite time? We give a simple condition on $\lambda$ for this {\em hegemony} property to hold, and another simple condition for it to not hold, but there is a large gap between these conditions, which includes the case $\lambda(A,B) \equiv 1$. For this case, a non-rigorous analytic argument and simulations suggest hegemony.Comment: 13 page

The Effect of Glutamine in Modulating Exertional Heat Stress Response of Intestinal Cells in Trained and Untrained Runners

Glutamine is the preferred substrate of intestinal cells and is required for the protection of intestinal cells integrity, helping to prevent exercise-induced endotoxin leakage from the intestine during stressful conditions. Increased endotoxins in the blood circulation (also known as endotoxaemia) has been shown to trigger systemic inflammation which is implicated in exertional heat stroke. This study examined firstly whether orally administered glutamine helps to reduce intestinal injury following an acute high intensity exercise session in hot conditions and secondly whether there is a different outcome according to fitness levels in runners. A randomized, double-blinded crossover study design was utilized. Twelve runners unacclimatised to heat, divided into trained [T; n=6; maximal oxygen uptake (VO2max) = 61.2 ± 1.0 ml∙kg-1∙min-1] and untrained (UT; n=6; VO2max = 51.0 ± 0.7 ml∙kg-1∙min-1) groups, ingested either a placebo or glutamine dipeptide supplement (L-alanyl-L-glutamine; 0.2 g/kg bodyweight/day) for 5 consecutive days before running at 70%VO2max in a climate chamber (30°C, 40% relative humidity) for 1 hour. Cardiac output, stroke volume, heart rates, sweat loss, percent dehydration, rectal and skin surface temperatures were measured. Venous blood samples at baseline, immediately after completion of run and 1-hour post run were analysed for endotoxins and intestinal fatty acid binding proteins (I-FABP) as markers of intestinal injury. Intestinal permeability was measured at pre and post exercise using dual sugar probes (L-R; lactulose and rhamnose). No significant difference was observed in all responses for training status. L-R ratios remained unchanged with or without glutamine. However, a significant main effect for time and treatment was observed for plasma I-FABP (

A Review of AAQ Variants and Other Context-Specific Measures of Psychological Flexibility

Psychological flexibility refers to a way of interacting with internal experiences and the external environment that advances one toward chosen values whereas psychological inflexibility reflects rigid adherence to ineffective responses such that valued living is compromised. Psychological flexibility is a critical variable of interest in acceptance and commitment therapy, thus, accurate assessment of this construct is pertinent to professionals in the field. Numerous measures of psychological flexibility for specific conditions exist and the psychometric validation of each of these measures varies in breadth and depth. To orient professionals to the scope of available measures as well as their psychometric properties, the current review summarizes the existing literature on context-specific measures of psychological flexibility. Most measures demonstrated satisfactory basic psychometric properties, though their clinical utility (e.g., treatment sensitivity) has largely been underexplored. Generally, context-specific measures performed better than a generic measure of psychological flexibility with respect to incremental validity and treatment sensitivity. Still, further research is needed to validate these measures (e.g., discriminant validity) in order to justify their use across settings and study designs

Anti-fouling double-skinned forward osmosis membrane with zwitterionic brush for oily wastewater treatment

Despite its attractive features for energy saving separation, the performance of forward osmosis (FO) has been restricted by internal concentration polarization and fast fouling propensity that occur in the membrane sublayer. These problems have significantly affected the membrane performance when treating highly contaminated oily wastewater. In this study, a novel double-skinned FO membrane with excellent anti-fouling properties has been developed for emulsified oil-water treatment. The double-skinned FO membrane comprises a fully porous sublayer sandwiched between a highly dense polyamide (PA) layer for salt rejection and a fairly loose dense bottom zwitterionic layer for emulsified oil particle removal. The top dense PA layer was synthesized via interfacial polymerization meanwhile the bottom layer was made up of a zwitterionic polyelectrolyte brush-(poly(3-(N-2-methacryloxyethyl-N,N-dimethyl) ammonatopropanesultone), abbreviated as PMAPS layer. The resultant double-skinned membrane exhibited a high water flux of 13.7 ± 0.3 L/m2.h and reverse salt transport of 1.6 ± 0.2 g/m2.h under FO mode using 2 M NaCl as the draw solution and emulsified oily solution as the feed. The double-skinned membrane outperforms the single-skinned membrane with much lower fouling propensity for emulsified oil-water separation

Online Process-Based Training for Perfectionism: A Randomized Trial

Process-based therapy (PBT) is model of psychotherapy designed to improve people’s ability to use a variety of skills from evidence-based treatments to match environmental needs and personal goals in the moment. This randomized trial tested the effect of an online self-help intervention modeled after PBT principles for participants with perfectionism (N = 77). The intervention comprised two four-session trainings teaching skills from different evidence-based treatments (e.g., cognitive-behavioral therapy, acceptance and commitment therapy) and targeting cognitive and motivational processes: (1) cognitive training and (2) motivational training respectively. Participants completed 17 assessments throughout the intervention and at 3- and 6-month follow-up. Results indicated that the full intervention led to improvement in perfectionism, self-compassion, psychological distress, and cognitive skills targeted by the cognitive intervention (e.g., cognitive defusion; absolute βs = 0.02 to 0.66). In addition, the second four-session training (i.e., training after first four-session training) was associated with improvements in perfectionism, self-compassion, quality of life, and psychological distress (absolute βs = .09 to 2.90), suggesting it had incremental benefit. Whereas the cognitive training appeared to specifically impact cognitive processes, the motivational training increased both cognitive and motivational processes. These findings provide initial support for the feasibility and efficacy of a process-based approach, because they show that participants can benefit from learning skills from different orientations and applying them with reference to their goals. However, specific aspects of the PBT model, including whether interventions can precisely improve targeted skills, still need to be empirically tested in larger and more diverse clinical samples

Memory function approach to the Hall constant in strongly correlated electron systems

The anomalous properties of the Hall constant in the normal state of high-$T_c$ superconductors are investigated within the single-band Hubbard model. We argue that the Mori theory is the appropriate formalism to address the Hall constant, since it aims directly at resistivities rather than conductivities. More specifically, the frequency dependent Hall constant decomposes into its infinite frequency limit and a memory function contribution. As a first step, both terms are calculated perturbatively in $U$ and on an infinite dimensional lattice, where $U$ is the correlation strength. If we allow $U$ to be of the order of twice the bare band width, the memory function contribution causes the Hall constant to change sign as a function of doping and to decrease as a function of temperature.Comment: 35 pages, RevTex, 3 ps figures include