706 research outputs found

    CMB temperature anisotropy at large scales induced by a causal primordial magnetic field

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    We present an analytical derivation of the Sachs Wolfe effect sourced by a primordial magnetic field. In order to consistently specify the initial conditions, we assume that the magnetic field is generated by a causal process, namely a first order phase transition in the early universe. As for the topological defects case, we apply the general relativistic junction conditions to match the perturbation variables before and after the phase transition which generates the magnetic field, in such a way that the total energy momentum tensor is conserved across the transition and Einstein's equations are satisfied. We further solve the evolution equations for the metric and fluid perturbations at large scales analytically including neutrinos, and derive the magnetic Sachs Wolfe effect. We find that the relevant contribution to the magnetic Sachs Wolfe effect comes from the metric perturbations at next-to-leading order in the large scale limit. The leading order term is in fact strongly suppressed due to the presence of free-streaming neutrinos. We derive the neutrino compensation effect dynamically and confirm that the magnetic Sachs Wolfe spectrum from a causal magnetic field behaves as l(l+1)C_l^B \propto l^2 as found in the latest numerical analyses.Comment: 31 pages, 2 figures, minor changes, matches published versio

    Економічні напрями енергетичної безпеки Європейського Союзу

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    Interactions between proteins are orchestrated in a precise and timedependent manner, underlying cellular function. The binding affinity, defined as the strength of these interactions, is translated into physico-chemical terms in the dissociation constant (Kd), the latter being an experimental measure that determines whether an interaction will be formed in solution or not. Predicting binding affinity from structural models has been a matter of active research for more than 40 years because of its fundamental role in drug development. However, all available approaches are incapable of predicting the binding affinity of protein–protein complexes from coordinates alone. Here, we examine both theoretical and experimental limitations that complicate the derivation of structure–affinity relationships. Most work so far has concentrated on binary interactions. Systems of increased complexity are far from being understood. The main physico-chemical measure that relates to binding affinity is the buried surface area, but it does not hold for flexible complexes. For the latter, there must be a significant entropic contribution that will have to be approximated in the future. We foresee that any theoretical modelling of these interactions will have to follow an integrative approach considering the biology, chemistry and physics that underlie protein–protein recognition

    Cost-efficient production of in vitro Rhizophagus irregularis.

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    One of the bottlenecks in mycorrhiza research is that arbuscular mycorrhizal fungi (AMF) have to be cultivated with host plant roots. Some AMF species, such as Rhizophagus irregularis, can be grown in vitro on dual-compartment plates, where fungal material can be harvested from a fungus-only compartment. Plant roots often grow into this fungus compartment, and regular root trimming is required if the fungal material needs to be free of traces of plant material. Trimming also increases unwanted contamination by other microorganisms. We compared 22 different culture types and conditions to a widely used dual-compartment culture system that we refer to as the "standard system." We found two modified culture systems that allowed high spore production and low rates of contamination. We then compared the two modified culture systems with the standard system in more detail. In the two modified culture systems versus the standard system, a comparable number of spores were produced per plate, the necessity for root trimming was reduced, and there was significantly diminished contamination in the fungal compartment. A cost analysis showed that both modified culture systems were more economic than the standard culture system for the production of the same number of non-contaminated spores. The two modified culture systems provide an economic alternative for the production of contaminant-free fungal material which is ideal for studies requiring AMF DNA or RNA for genetics, genomics, and transcriptomic studies or for studies requiring relatively large amounts of fungal material for greenhouse experiments

    Effect of Peculiar Motion in Weak Lensing

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    We study the effect of peculiar motion in weak gravitational lensing. We derive a fully relativistic formula for the cosmic shear and the convergence in a perturbed Friedmann Universe. We find a new contribution related to galaxies peculiar velocity. This contribution does not affect cosmic shear in a measurable way, since it is of second order in the velocity. However, its effect on the convergence (and consequently on the magnification, which is a measurable quantity) is important, especially for redshifts z < 1. As a consequence, peculiar motion modifies also the relation between the shear and the convergence.Comment: 11 pages, 7 figures; v2: discussion on the reduced shear added (5.C), additional references, version accepted in PRD; v3: mistakes corrected in eqs. (26), (31), (33) and (44); results unchange

    34* Tracheal structure abnormalities in Cftr-/- knockout mice

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    Healthcare professionals' sources of knowledge of complementary medicine in an academic center.

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    Complementary medicine (CM) is utilized in a growing number of academic centers despite the debate concerning its value, risks and benefits. Healthcare professionals often feel uncomfortable discussing CM with patients, and little is known about their sources of knowledge in the field of CM. To assess healthcare professionals' sources of knowledge and attitude toward CM in an academic hospital. The cross-sectional web-based survey took place from October to December 2013. A total of 4,925 healthcare professionals working at Lausanne University Hospital, Switzerland, were invited to answer the questionnaire. Factors influencing healthcare professionals' opinion toward CM, knowledge and communication about CM. The questionnaire was answered by 1,247 healthcare professionals. The three key factors influencing professionals' opinion toward CM were personal experience, clinical experience and evidence demonstrating the physiological mechanism of CM. Personal experience was more associated with nurses' and midwives' opinion compared to physicians' (80.8% vs 57.1%, OR = 3.08, [95% CI: 2.35-4.05], P&lt;0.001 and 85.3% vs 57.1%, OR = 3.83, [95% CI: 1.95-7.53], P&lt;0.001, respectively) as well as with professionals trained in CM compared to non-trained professionals (86.0% vs 73.2%, OR = 2.60, [95% CI: 1.92-3.53], P&lt;0.001). Physicians relied more on randomized controlled clinical trials compared to nurses (81.3% vs 62.9%, OR = 0.43, [95% CI: 0.33-0.57], P&lt;0.001). A majority of the respondents (82.5%) agreed that they lacked knowledge about CM and 65.0% noted that it was the patient who initially started the discussion about CM. Different professionals used different strategies to forge opinions regarding CM: physicians relied more on scientific evidence, while nurses and midwives were more influenced by personal experience. Regardless of preferred information source, most respondents did not feel prepared to address patient questions regarding CM. Enhancing interprofessional education opportunities is an important strategy to help providers become empowered to discuss CM with patients. This in turn will help patients making informed decisions in their healthcare

    Dipolar modulation in the size of galaxies: The effect of Doppler magnification

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    Strongly lensed SNe Ia in the era of LSST: observing cadence for lens discoveries and time-delay measurements

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    The upcoming Large Synoptic Survey Telescope (LSST) will detect many strongly lensed Type Ia supernovae (LSNe Ia) for time-delay cosmography. This will provide an independent and direct way for measuring the Hubble constant H0H_0, which is necessary to address the current 4.4σ4.4 \sigma tension in H0H_0 between the local distance ladder and the early Universe measurements. We present a detailed analysis of different observing strategies for the LSST, and quantify their impact on time-delay measurement between multiple images of LSNe Ia. For this, we produced microlensed mock-LSST light curves for which we estimated the time delay between different images. We find that using only LSST data for time-delay cosmography is not ideal. Instead, we advocate using LSST as a discovery machine for LSNe Ia, enabling time delay measurements from follow-up observations from other instruments in order to increase the number of systems by a factor of 2 to 16 depending on the observing strategy. Furthermore, we find that LSST observing strategies, which provide a good sampling frequency (the mean inter-night gap is around two days) and high cumulative season length (ten seasons with a season length of around 170 days per season), are favored. Rolling cadences subdivide the survey and focus on different parts in different years; these observing strategies trade the number of seasons for better sampling frequency. In our investigation, this leads to half the number of systems in comparison to the best observing strategy. Therefore rolling cadences are disfavored because the gain from the increased sampling frequency cannot compensate for the shortened cumulative season length. We anticipate that the sample of lensed SNe Ia from our preferred LSST cadence strategies with rapid follow-up observations would yield an independent percent-level constraint on H0H_0.Comment: 25 pages, 22 figures; accepted for publication in A&
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