Improved parallelization techniques for the density matrix renormalization group

A distributed-memory parallelization strategy for the density matrix renormalization group is proposed for cases where correlation functions are required. This new strategy has substantial improvements with respect to previous works. A scalability analysis shows an overall serial fraction of 9.4% and an efficiency of around 60% considering up to eight nodes. Sources of possible parallel slowdown are pointed out and solutions to circumvent these issues are brought forward in order to achieve a better performance.Comment: 8 pages, 4 figures; version published in Computer Physics Communication

Thermal and Hadrochemical Equilibration in Nucleus-Nucleus Collisions at the SPS

The currently available set of hadron abundances at the SPS for central S+Au(W,Pb) collisions is compared to predictions from a scenario assuming local thermal and hadrochemical equilibrium. The data are consistent with a freeze-out temperature T = 160-170 MeV. Spectra are consistent with this temperature range and a moderate transverse expansion. The freeze-out points at the AGS and SPS are found to be close to the phase boundary between a hadron gas and an ideal quark-gluon phase.Comment: 14 pages + 3 figures. Paper replaced with version accepted for publication in Phys. Lett.

Our Voices

Our dissenting voices call for the dismantling of all identity-based power hierarchies that silence and oppress marginalized voices. We attempt to understand how the invisible forces of a binary world put women into roles of “lesser”

Applying Mendelian randomization to appraise causality in relationships between smoking, depression and inflammation

Smoking, inflammation and depression commonly co-occur and may be mechanistically linked. However, key questions remain around the direction of association and the influence of residual confounding. We aimed to characterize the association between lifetime smoking and depression, as well as to assess the role that genetically-predicted C-reactive protein (CRP) level, (an archetypal generalized inflammatory marker) and/or IL-6 activity, as a potential explanation for this association. We performed inverse variance weighted Mendelian randomization (MR) analyses using recently published summary-level GWAS data for lifetime smoking index, CRP levels, and depression. A subset of inflammatory-related genetic variants from the lifetime smoking GWAS were also used to assess the potential inflammatory causal pathways between smoking and depression. The analysis indicated reciprocal relationships of lifetime smoking with depression (ORSmk–Dep = 2.01, 95% CI 1.71–2.37, p &lt; 0.001; ORDep–Smk = 1.09, 95% CI 1.06–1.13, p &lt; 0.001), CRP levels and IL-6 activity (ORSmk–CRP = 1.40, 95% CI 1.21–1.55, p &lt; 0.001; ORCRP–Smk = 1.03, 95% CI 1.02–1.05, p &lt; 0.001, ORIL-6/CRP–Smk = 1.06 (1.03–1.09), p &lt; 0.001). These associations were also supported by the majority of the robust MR methods performed. We did not find evidence for a reciprocal relationship between CRP levels (using &gt; 500 genetic instruments for CRP) and depression (ORCRP–Dep = 1.01, 95% CI 0.99–1.04; ORDep–CRP = 1.03, 95% CI 0.99–1.07). We observed little variation in the IVW estimates between smoking and depression when we limited the genetic variants assessed to those related to measures of generalized inflammation, but we found evidence for an attenuation of the smoking-depression association in multivariable mendelian randomization when adjusting for IL-6 activity, suggesting that the IL-6 pathway may be at least in part responsible for the association of smoking and depression. Our study supports potential bidirectional causal associations between lifetime smoking and depression which may be at least in part explained by the IL-6 signalling pathway. The IL-6 pathway may represent a putative therapeutic target for smoking and to mitigate the effects of smoking on depression.</p

Assessing Peracetic Acid Application Methodology and Impacts on Fluidized Sand Biofilter Performance

Nitrifying biofilters oxidize harmful ammonia excreted by fish into less toxic nitrate within recirculating aquaculture systems (RAS). Biofilter performance and resulting RAS water quality largely depend on a robust microbiome that effectively converts nitrogenous wastes; however, occasional use of water disinfectants may also be necessary to reduce or eliminate specific fish pathogens. Disinfectants and sanitizers such as peracetic acid (PAA) work by disrupting microbial activity and could unintentionally alter the microbially-driven nitrification biofiltration process if allowed to circulate within an RAS. Furthermore, the target concentration and application method of PAA may influence the level of biofilter disruption. For this study, 12 replicated experimental-scale fluidized sand biofilters were dosed with PAA to achieve target concentrations ranging from 1.0-–2.5 mg/L, a typical low-dose treatment range to reduce or eliminate opportunistic pathogens. Two application methods were compared, including (i) a single pulse of PAA added every other day for five days, and (ii) smaller doses of PAA added every five minutes over four hours. The PAA decay was monitored and predosing and postdosing water quality parameters were assessed. Regardless of the target concentration or application method, PAA addition within the tested range did not cause significant disruption to the biofilters’ nitrification processes. This research demonstrates that PAA may be a viable water sanitizer for the RAS industry, although further research to refine safe application protocols is necessary.Assessing Peracetic Acid Application Methodology and Impacts on Fluidized Sand Biofilter PerformancepublishedVersio

An evaluation of the site specificity of soil elemental signatures for identifying and interpreting former functional areas

Soil multi-element analysis is now a routine technique employed to help answer questions about space use and function in and around archaeological sites. The pattern of enhancement of certain elements, including P, Pb, Ca, Zn, and Cu, has been shown by numerous studies to correlate closely with the archaeological and historical record. Interpretation of these soil signatures, however, has generally been more problematic. One approach to the problem has been the use of ethnographic or “known” sites to guide interpretation, but how confidently can results from one site be extrapolated to another? This study of abandoned farms tests the site specificity of soil multi-element signatures of past space use through the use of discriminant models. Data analysis suggests that one to one comparisons of similar sites are much less accurate (38% accuracy) than comparisons based on a wider range of sites (59.3% accuracy), even when the latter have contrasting geology. The results highlight the importance of individual anthropogenic practices during occupation and abandonment in the development of diagnostic soil geochemical signatures

Neutrinos from the pulsar wind nebulae

In the recent paper we calculated the $\gamma$-ray spectra from pulsar wind nebulae (PWNe), assuming that a significant amount of the pulsar rotational energy is converted into relativistic nuclei. These nuclei accelerate leptons which are responsible for most of the observed electromagnetic emission from PWNe. Small part of nuclei also interact with the matter of the supernova producing $\gamma$-rays, which can also contribute to the observed spectra of young nebulae. Here we calculate the spectra of neutrinos from the interaction of nuclei inside the nebula and the expected neutrino event rates in the 1 km$^2$ neutrino detector from: the Crab Nebula (PSR 0531+21), the Vela SNR (PSR 0833-45), G 343.1-2.3 (PSR 1706-44), MSH15-52 (PSR 1509-58), 3C58 (PSR J0205+6449), and CTB80 (PSR 1951+32). It is shown that only the Crab Nebula can produce the neutrino event rate above the sensitivity limit of the 1 km$^2$ neutrino detector, provided that nuclei take most of the rotational energy lost by the pulsar. The neutrino event rate expected from the Vela SNR is comparable to that from the Crab Nebula but these neutrinos are less energetic and emitted from a much larger region on the sky. Therefore it may be difficult to subtract the Vela SNR signal from the higher background of the atmospheric neutrinos.Comment: 7 pages, 3 figures, A&A style, accepted to A&