916 research outputs found

    Aminoacyl tRNA synthetase complex interacting multifunctional protein 1 simultaneously binds Glutamyl-Prolyl-tRNA synthetase and scaffold protein aminoacyl tRNA synthetase complex interacting multifunctional protein 3 of the multi-tRNA synthetase complex

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    Higher eukaryotes have developed extensive compartmentalization of amino acid (aa) - tRNA coupling through the formation of a multi-synthetase complex (MSC) that is composed of eight aa-tRNA synthetases (ARS) and three scaffold proteins: aminoacyl tRNA synthetase complex interacting multifunctional proteins (AIMP1, 2 and 3). Lower eukaryotes have a much smaller complex while yeast MSC consists of only two ARS (MetRS and GluRS) and one ARS cofactor 1 protein, Arc1p (Simos et al., 1996), the homolog of the mammalian AIMP1. Arc1p is reported to form a tripartite complex with GluRS and MetRS through association of the N-terminus GST-like domains (GST-L) of the three proteins (Koehler et al., 2013). Mammalian AIMP1 has no GST-L domain corresponding to Arc1p N-terminus. Instead, AIMP3, another scaffold protein of 18 kDa composed entirely of a GST-L domain, interacts with Methionyl-tRNA synthetase (MARS) (Quevillon et al., 1999) and Glutamyl-Prolyl-tRNA Synthetase (EPRS) (Cho et al., 2015). Here we report two new interactions between MSC members: AIMP1 binds to EPRS and AIMP1 binds to AIMP3. Interestingly, the interaction between AIMP1 and AIMP3 complex makes it the functional equivalent of a single Arc1p polypeptide in yeast. This interaction is not mapped to AIMP1 N-terminal coiled-coil domain, but rather requires an intact tertiary structure of the entire protein. Since AIMP1 also interacts with AIMP2, all three proteins appear to compose a core docking structure for the eight ARS in the MSC complex

    Relativistically invariant quantum information

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    We show that quantum information can be encoded into entangled states of multiple indistinguishable particles in such a way that any inertial observer can prepare, manipulate, or measure the encoded state independent of their Lorentz reference frame. Such relativistically invariant quantum information is free of the difficulties associated with encoding into spin or other degrees of freedom in a relativistic context.Comment: 5 pages, published versio

    Reprogramming of lysosomal gene expression by interleukin-4 and Stat6.

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    BACKGROUND: Lysosomes play important roles in multiple aspects of physiology, but the problem of how the transcription of lysosomal genes is coordinated remains incompletely understood. The goal of this study was to illuminate the physiological contexts in which lysosomal genes are coordinately regulated and to identify transcription factors involved in this control. RESULTS: As transcription factors and their target genes are often co-regulated, we performed meta-analyses of array-based expression data to identify regulators whose mRNA profiles are highly correlated with those of a core set of lysosomal genes. Among the ~50 transcription factors that rank highest by this measure, 65% are involved in differentiation or development, and 22% have been implicated in interferon signaling. The most strongly correlated candidate was Stat6, a factor commonly activated by interleukin-4 (IL-4) or IL-13. Publicly available chromatin immunoprecipitation (ChIP) data from alternatively activated mouse macrophages show that lysosomal genes are overrepresented among Stat6-bound targets. Quantification of RNA from wild-type and Stat6-deficient cells indicates that Stat6 promotes the expression of over 100 lysosomal genes, including hydrolases, subunits of the vacuolar H⁺ ATPase and trafficking factors. While IL-4 inhibits and activates different sets of lysosomal genes, Stat6 mediates only the activating effects of IL-4, by promoting increased expression and by neutralizing undefined inhibitory signals induced by IL-4. CONCLUSIONS: The current data establish Stat6 as a broadly acting regulator of lysosomal gene expression in mouse macrophages. Other regulators whose expression correlates with lysosomal genes suggest that lysosome function is frequently re-programmed during differentiation, development and interferon signaling

    Hybrid Quantum and Classical Mechanical Monte Carlo Simulations of the Interaction of Hydrogen Chloride with Solid Water Clusters

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    Monte Carlo simulations using a hybrid quantum and classical mechanical potential were performed for crystal and amorphous-like HCl-water(n) clusters The subsystem composed by HCl and one water molecule was treated within Density Functional Theory, and a classical force field was used for the rest of the system. Simulations performed at 200 K suggest that the energetic feasibility of HCl dissociation strongly depends on its initial placement within the cluster. An important degree of ionization occurs only if HCl is incorporated into the surface. We observe that local melting does not play a crucial role in the ionization process.Comment: 14 Latex pages with 4 postscript figures, to appear in Chem. Phys. Let

    Capability in the digital: institutional media management and its dis/contents

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    This paper explores how social media spaces are occupied, utilized and negotiated by the British Military in relation to the Ministry of Defence’s concerns and conceptualizations of risk. It draws on data from the DUN Project to investigate the content and form of social media about defence through the lens of ‘capability’, a term that captures and describes the meaning behind multiple representations of the military institution. But ‘capability’ is also a term that we hijack and extend here, not only in relation to the dominant presence of ‘capability’ as a representational trope and the extent to which it is revealing of a particular management of social media spaces, but also in relation to what our research reveals for the wider digital media landscape and ‘capable’ digital methods. What emerges from our analysis is the existence of powerful, successful and critically long-standing media and reputation management strategies occurring within the techno-economic online structures where the exercising of ‘control’ over the individual – as opposed to the technology – is highly effective. These findings raise critical questions regarding the extent to which ‘control’ and management of social media – both within and beyond the defence sector – may be determined as much by cultural, social, institutional and political influence and infrastructure as the technological economies. At a key moment in social media analysis, then, when attention is turning to the affordances, criticisms and possibilities of data, our research is a pertinent reminder that we should not forget the active management of content that is being similarly, if not equally, effective

    Auto-extinction of engineered timber

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    Engineered timber products are becoming increasingly popular in the construction industry due to their attractive aesthetic and sustainability credentials. Cross-laminated timber (CLT) is one such engineered timber product, formed of multiple layers of timber planks glued together with adjacent layers perpendicular to each other. Unlike traditional building materials such as steel and concrete, the timber structural elements can ignite and burn when exposed to fire, and thus this risk must be explicitly addressed during design. Current design guidance focusses on the structural response of engineered timber, with the flammability risk typically addressed by encapsulation of any structural timber elements with the intention of preventing their involvement in a fire. Exposed structural timber elements may act as an additional fuel load, and this risk must be adequately quantified to satisfy the intent of the building regulations in that the structure does not continue burning. This can be achieved through timber’s natural capacity to auto-extinguish when the external heat source is removed or sufficiently reduced. To address these issues, a fundamental understanding of auto-extinction and the conditions necessary to achieve it in real fire scenarios is needed. Bench-scale flammability studies were undertaken in the Fire Propagation Apparatus to explore the conditions under which auto-extinction will occur. Critical conditions were determined experimentally as a mass loss rate of 3.48 ± 0.31 g/m2s, or an incident heat flux of ~30 kW/m2. Mass loss rate was identified as the better criterion, as critical heat flux was shown by comparison with literature data to be heavily dependent on apparatus. Subsequently, full-scale compartment fire experiments with exposed timber surfaces were performed to determine if auto-extinction could be achieved in real fire scenarios. It was demonstrated that auto-extinction could be achieved in a compartment fire scenario, but only if significant delamination of the engineered timber product could be prevented. A full-scale compartment fire experiment with an exposed back wall and ceiling achieved auto-extinction after around 21 minutes, at which point no significant delamination of the first lamella had been observed. Experiments with an exposed back and side wall, and experiments with an exposed back wall, side wall, and ceiling underwent sustained burning due to repeated delamination, and an increased quantity of exposed timber respectively. Firepoint theory was used to predict the mass loss rate as a function of external heat flux and heat losses, and was successfully applied to the bench-scale experiments. This approach was then extended to the full-scale compartment fire experiment which achieved auto-extinction. A simplified approach based on experimentally obtained internal temperature fields was able to predict auto-extinction if delamination had not occurred – predicting an extinction time of 20-21 minutes. This demonstrates that the critical mass loss rate of 3.48 ± 0.31 g/m2s determined from bench-scale experiments was valid for application to full-scale compartment fire experiments. This was further explored through a series of reduced-scale compartment fire experiments, demonstrating that auto-extinction can only reliably be achieved if burnout of the compartment fuel load is achieved before significant delamination of the outer lamella takes place. The quantification of the auto-extinction phenomena and their applicability to full-scale compartment fires explored herein thus allows greater understanding of the effects of exposed timber surfaces on compartment fire dynamics

    Development of a Low-Resource Combined Gamma-Ray and Neutron Spectrometer for Planetary Science

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    Planetary neutron and gamma-ray spectroscopy (NGRS) has become a standard technique to measure distinctive geochemical composition and volatile abundance signatures for key elements relevant to planetary structure and evolution. Previous NGRS measurements have led to the discovery of the concentration of many elements including hydrogen on the Moon, Mars, Mercury, and the asteroids Eros, Vesta, and Ceres, but by utilizing separate NGRS. We have developed the Elpasolite Planetary Ice and Composition Spectrometer (EPICS) instrument, an innovative and combined NGRS with low resource requirements. EPICS incorporates elpasolite scintillator read out by silicon photomultipliers (SiPMs) to provide significant reduction in size, weight, and power, while achieving excellent neutron detection sensitivity and gamma-ray energy resolution as good as 2.9% full-width half-maximum at 662 keV. EPICS is ideally suited to resource constrained missions and is applicable to numerous targets such as the Moon, Mars, and small planetary bodies. An overview of the EPICS instrument and its simulated performance on a few notional missions is presented. We have integrated and done performance testing of a prototype of the EPICS instrument, including optimization of an amplification and summing circuit for a 64-element SiPM array that preserves pulse shape discrimination capability, which will be summarized

    Biomechanical analysis of the penalty-corner drag-flick of elite male and female hockey players

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    The aim of this study was to analyse the kinematic sequencing in the penalty-corner drag-flicks of elite male and female field hockey players of international calibre. Thirteen participants (one skilled male drag-flicker and six male and six female elite players) participated in the study. An optoelectronic motion analysis system was used to capture the drag-flicks with six cameras, sampling at 250 Hz. Select ground reaction force parameters were obtained from a force platform which registered the last support of the front foot. Twenty trials were captured from each subject. Both player groups showed significantly (p < 0.05) smaller ball velocity at release, peak angular velocity of the pelvis, and negative and positive peak angular velocities of the stick than the skilled subject. Normalised ground reaction forces of the gender groups were also smaller than that of the skilled drag-flicker. By comparing these players we established that the cues of the skill level are a wide stance, a whipping action (rapid back lift) of the stick followed by an explosive sequential movement of the pelvis, upper trunk and stick
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