Low-Energy Theorems from Holography

In the context of gauge/gravity duality, we verify two types of gauge theory low-energy theorems, the dilation Ward identities and the decoupling of heavy flavor. First, we provide an analytic proof of non-trivial dilation Ward identities for a theory holographically dual to a background with gluon condensate (the self-dual Liu--Tseytlin background). In this way an important class of low-energy theorems for correlators of different operators with the trace of the energy-momentum tensor is established, which so far has been studied in field theory only. Another low-energy relationship, the so-called decoupling theorem, is numerically shown to hold universally in three holographic models involving both the quark and the gluon condensate. We show this by comparing the ratio of the quark and gluon condensates in three different examples of gravity backgrounds with non-trivial dilaton flow. As a by-product of our study, we also obtain gauge field condensate contributions to meson transport coefficients.Comment: 32 pages, 4 figures, two references added, typos remove

How does Low Back Pain Influence Muscle Activity during a Cyclical Dynamic Lifting Task?

Title How does LBP Influence Muscle Activity during a Cyclical Dynamic Lifting Task? Authors Andy Sanderson, Corrado Cescon, Nicola R. Heneghan, Alison Rushton, Marco Barbero, Pauline Kuithan, Deborah Falla Purpose Chronic non-specific low back pain (cLBP) is a leading cause of disability, limiting activity in 540 million people globally. High-density electromyography (HDEMG) has been used to investigate changes in back muscle activity in people with cLBP. Previous studies have utilised static or mono-planar tasks or focussed on small areas of the erector spinae (ES). This study uses innovative HDEMG and kinematic analysis to investigate the effect of cLBP on muscle activity and movement during a multi-planar lifting task. Methods Sixteen people with cLBP (8 male, age: 26.9±10.8 years) and sixteen age and gender-matched controls (7 male, age: 31.7±14.0 years) completed the study. HDEMG signals from the ES were detected with four 64-channel semi-disposable 13x5 electrode grids (2 grids bilaterally) covering the lumbar and thoraco-lumbar ES. Kinematic surface markers were placed over the back, enabling 3D motion capture. HDEMG and kinematic data were recorded continuously during a dynamic task involving the cyclical lifting of a 5kg box between 6 shelves for 10 cycles (~7 minutes). The shelves were arranged around the participant, at knee and sternal height, with one pair of shelves anterior and two pairs lateral. To the beat of a metronome, the participant moved the box between shelves, returning to a central shelf each time (10 movements). HDEMG amplitude data were normalised to the first cycle for each movement to a shelf, and factorial ANOVA’s used to compare subsequent cycles to the first. Results Kinematic analysis revealed no significant differences between groups in the movement pattern used to complete the lifting task (P>0.05 for all relevant outcomes). Despite similar movements, significant differences in muscle activity, were seen between groups. The cLBP group showed systematically higher amplitude, indicating higher levels of muscle activity, in 6/10 shelf movements (P0.05). Conclusion As the data were normalised and amplitude is a measure of muscle activity, these results indicate that for a majority of movements, the activity in the ES for the LBP group did not show as great a reduction over the task as that of the control group. These data therefore support an altered motor control strategy in participants with cLBP. While no differences were found in the movement strategy, likely due to the standardisation of the task, cLBP participants showed lower reductions in activity, indicating that already fatigued or dysfunctional muscles remained in use throughout the task

Load-sharing policies in parallel simulation of agent-based demographic models

Execution parallelism in agent-Based Simulation (ABS) allows to deal with complex/large-scale models. This raises the need for runtime environments able to fully exploit hardware parallelism, while jointly offering ABS-suited programming abstractions. In this paper, we target last-generation Parallel Discrete Event Simulation (PDES) platforms for multicore systems. We discuss a programming model to support both implicit (in-place access) and explicit (message passing) interactions across concurrent Logical Processes (LPs). We discuss different load-sharing policies combining event rate and implicit/explicit LPs’ interactions. We present a performance study conducted on a synthetic test case, representative of a class of agent-based models.Peer ReviewedPostprint (author's final draft

Noiseonomics: The relationship between ambient noise levels in the sea and global economic trends

In recent years, the topic of noise in the sea and its effects on marine mammals has attracted considerable attention from both the scientific community and the general public. Since marine mammals rely heavily on acoustics as a primary means of communicating, navigating, and foraging in the ocean, any change in their acoustic environment may have an impact on their behavior. Specifically, a growing body of literature suggests that low-frequency, ambient noise levels in the open ocean increased approximately 3.3 dB per decade during the period 1950–2007. Here we show that this increase can be attributed primarily to commercial shipping activity, which in turn, can be linked to global economic growth. As a corollary, we conclude that ambient noise levels can be directly related to global economic conditions. We provide experimental evidence supporting this theory and discuss its implications for predicting future noise levels based on global economic trends

Screening for HIV-Associated Tuberculosis and Rifampicin Resistance before Antiretroviral Therapy Using the Xpert MTB/RIF Assay: A Prospective Study

In a prospective study, Stephen Lawn and colleagues find that pre-ART screening with Xpert MTB/RIF increased tuberculosis case detection by 45% compared to smear microscopy in HIV-positive patients at high risk of TB risk. AE competing interests must also pull through to the proof. “The Academic Editor, Madhukar Pai, declares that he consults for the Bill & Melinda Gates Foundation (BMGF). The BMGF supported FIND which was involved in the development of the Xpert MTB/RIF assay. He also co-chairs the Stop TB Partnership's New Diagnostics Working Group that was involved in the WHO endorsement of the Xpert assay.” Linked: Scott pmed.1001061; Evans pmed.1001064; Dowdy pmed.100106

A transient homotypic interaction model for the influenza A virus NS1 protein effector domain

Influenza A virus NS1 protein is a multifunctional virulence factor consisting of an RNA binding domain (RBD), a short linker, an effector domain (ED), and a C-terminal 'tail'. Although poorly understood, NS1 multimerization may autoregulate its actions. While RBD dimerization seems functionally conserved, two possible apo ED dimers have been proposed (helix-helix and strand-strand). Here, we analyze all available RBD, ED, and full-length NS1 structures, including four novel crystal structures obtained using EDs from divergent human and avian viruses, as well as two forms of a monomeric ED mutant. The data reveal the helix-helix interface as the only strictly conserved ED homodimeric contact. Furthermore, a mutant NS1 unable to form the helix-helix dimer is compromised in its ability to bind dsRNA efficiently, implying that ED multimerization influences RBD activity. Our bioinformatical work also suggests that the helix-helix interface is variable and transient, thereby allowing two ED monomers to twist relative to one another and possibly separate. In this regard, we found a mAb that recognizes NS1 via a residue completely buried within the ED helix-helix interface, and which may help highlight potential different conformational populations of NS1 (putatively termed 'helix-closed' and 'helix-open') in virus-infected cells. 'Helix-closed' conformations appear to enhance dsRNA binding, and 'helix-open' conformations allow otherwise inaccessible interactions with host factors. Our data support a new model of NS1 regulation in which the RBD remains dimeric throughout infection, while the ED switches between several quaternary states in order to expand its functional space. Such a concept may be applicable to other small multifunctional proteins