572 research outputs found
The Origin and Evolution of the Galaxy Mass-Metallicity Relation
We use high-resolution cosmological zoom-in simulations from the Feedback in
Realistic Environment (FIRE) project to study the galaxy mass-metallicity
relations (MZR) from z=0-6. These simulations include explicit models of the
multi-phase ISM, star formation, and stellar feedback. The simulations cover
halo masses Mhalo=10^9-10^13 Msun and stellar mass Mstar=10^4-10^11 Msun at z=0
and have been shown to produce many observed galaxy properties from z=0-6. For
the first time, our simulations agree reasonably well with the observed
mass-metallicity relations at z=0-3 for a broad range of galaxy masses. We
predict the evolution of the MZR from z=0-6 as
log(Zgas/Zsun)=12+log(O/H)-9.0=0.35[log(Mstar/Msun)-10]+0.93 exp(-0.43 z)-1.05
and log(Zstar/Zsun)=[Fe/H]-0.2=0.40[log(Mstar/Msun)-10]+0.67 exp(-0.50 z)-1.04,
for gas-phase and stellar metallicity, respectively. Our simulations suggest
that the evolution of MZR is associated with the evolution of stellar/gas mass
fractions at different redshifts, indicating the existence of a universal
metallicity relation between stellar mass, gas mass, and metallicities. In our
simulations, galaxies above Mstar=10^6 Msun are able to retain a large fraction
of their metals inside the halo, because metal-rich winds fail to escape
completely and are recycled into the galaxy. This resolves a long-standing
discrepancy between "sub-grid" wind models (and semi-analytic models) and
observations, where common sub-grid models cannot simultaneously reproduce the
MZR and the stellar mass functions.Comment: 17 pages, 14 figures, re-submitted to MNRAS after revisions on
referee comment
Novel phylogenetic algorithm to monitor human tropism in Egyptian H5N1-HPAIV reveals evolution toward efficient human-to-human transmission
Years of endemic infections with highly pathogenic avian influenza (HPAI) A subtype H5N1 virus in poultry and high numbers of infections in humans provide ample opportunity in Egypt for H5N1-HPAIV to develop pandemic potential. In an effort to better understand the viral determinants that facilitate human infections of the Egyptian H5N1-HPAIVvirus, we developed a new phylogenetic algorithm based on a new distance measure derived from the informational spectrum method (ISM). This new approach, which describes functional aspects of the evolution of the hemagglutinin subunit 1 (HA1), revealed a growing group G2 of H5N1-HPAIV in Egypt after 2009 that acquired new informational spectrum (IS) properties suggestive of an increased human tropism and pandemic potential. While in 2006 all viruses in Egypt belonged to the G1 group, by 2011 these viruses were virtually replaced by G2 viruses. All of the G2 viruses displayed four characteristic mutations (D43N, S120(D,N), (S,L)129Δ and I151T), three of which were previously reported to increase binding to the human receptor. Already in 2006–2008 G2 viruses were significantly (p<0.02) more often found in humans than expected from their overall prevalence and this further increased in 2009–2011 (p<0.007). Our approach also identified viruses that acquired additional mutations that we predict to further enhance their human tropism. The extensive evolution of Egyptian H5N1-HPAIV towards a preferential human tropism underlines an urgent need to closely monitor these viruses with respect to molecular determinants of virulence
The Effect of Movement Therapy on Negative Symptoms in Schizophrenia - A Multicenter Randomized Controlled Trial
Objective: Negative symptoms of patients with Schizophrenia are resistant to
medical treatment or conventional group therapy. Understanding schizophrenia
as a form of disembodiment of the self, a number of scientists have argued
that the approach of embodiment and associated embodied therapies, such as
Dance and Movement Therapy (DMT) or Body Psychotherapy (BPT), may be more
suitable to explain the psychopathology underlying the mental illness and to
address its symptoms. Hence the present randomized controlled trial
(DRKS00009828, http://apps.who.int/trialsearch/) aimed to examine the
effectiveness of manualized movement therapy (BPT/DMT) on the negative
symptoms of patients with schizophrenia. Method:A total of 68 out-patients
with a diagnosis of a schizophrenia spectrum disorder were randomly allocated
to either the treatment (n = 44, 20 sessions of BPT/DMT) or the control
condition [n = 24, treatment as usual (TAU)]. Changes in negative symptom
scores on the Scale for the Assessment of Negative Symptoms (SANS) were
analyzed using Analysis of Covariance (ANCOVA) with Simpson-Angus Scale (SAS)
scores as covariates in order to control for side effects of antipsychotic
medication. Results:After 20 sessions of treatment (BPT/DMT or TAU), patients
receiving movement therapy had significantly lower negative symptom scores
(SANS total score, blunted affect, attention). Effect sizes were moderate and
mean symptom reduction in the treatment group was 20.65%. Conclusion:The study
demonstrates that embodied therapies, such as BPT/DMT, are highly effective in
the treatment of patients with schizophrenia. Results strongly suggest that
BPT/DMT should be embedded in the daily clinical routine
Meat substitutes : Resource demands and environmental footprints
FThe modern food system is characterized with high environmental impact, which is in many cases associated with increased rates of animal production and overconsumption. The adoption of alternatives to meat proteins (insects, plants, mycoprotein, microalgae, cultured meat, etc.) might potentially influence the environmental impact and human health in a positive or negative way but could also trigger indirect impacts with higher consumption rates. Current review provides a condensed analysis on potential environmental impacts, resource consumption rates and unintended trade-offs associated with integration of alternative proteins in complex global food system in the form of meat substitutes. We focus on emissions of greenhouse gases, land use, non-renewable energy use and water footprint highlighted for both ingredients used for meat substitutes and ready products. The benefits and limitations of meat substitution are highlighted in relation to a weight and protein content. The analysis of the recent research literature allowed us to define issues, that require the attention of future studies.Peer reviewe
CO Luminosity Functions For FIR and B-band Selected Galaxies and the First Estimate for Omega_{HI+H2}
We derive a non-parametric CO luminosity function using a FIR and an optical
B-band selected sample of the galaxies included in the FCRAO Extragalactic CO
Survey. The FIR selected sample is defined using the IRAS Bright Galaxy Surveys
(BGS; IRAS 60 micron flux density >= 5.24 Jy). Although our CO sample is not
complete, the normalization using the BGS reproduces the IRAS 60 micron
luminosity function in excellent agreement with those found in the literature.
Similarly, a B-band selected sample defined using the Revised Shapley-Ames
(RSA) catalog is used to derive a CO luminosity function for a comparison. A
Schechter function describes the both derived CO luminosity functions
reasonably well. Adopting the standard CO-to-H2 conversion factor, we derive a
molecular gas density of rho_{H2}=(3.1\pm 1.2)*10^7h Mo Mpc^{-3} for the local
volume. Combining with the measurements of the local HI mass density and the
helium contribution, we estimate that the total mass density of cold neutral
gas in the local universe is Omega_{gas} =(4.3 \pm 1.1)*10^{-4} h^{-1}, which
is about 20% of the total stellar mass density Omega_{stars}.Comment: 16 pages, 11 figures uses aastex.cls and emulateapj5.sty. Accepted
for publication in Ap
Prospects of the WSR-88D Radar for Cloud Studies
This is the publisher's version, also available electronically from http://journals.ametsoc.org/doi/abs/10.1175/2010JAMC2303.1.Sounding of nonprecipitating clouds with the 10-cm wavelength Weather Surveillance Radar-1988 Doppler (WSR-88D) is discussed. Readily available enhancements to signal processing and volume coverage patterns of the WSR-88D allow observations of a variety of clouds with reflectivities as low as −25 dBZ (at a range of 10 km). The high sensitivity of the WSR-88D, its wide velocity and unambiguous range intervals, and the absence of attenuation allow accurate measurements of the reflectivity factor, Doppler velocity, and spectrum width fields in clouds to ranges of about 50 km. Fields of polarimetric variables in clouds, observed with a research polarimetric WSR-88D, demonstrate an abundance of information and help to resolve Bragg and particulate scatter. The scanning, Doppler, and polarimetric capabilities of the WSR-88D allow real-time, three-dimensional mapping of cloud processes, such as transformations of hydrometeors between liquid and ice phases. The presence of ice particles is revealed by high differential reflectivities and the lack of correlation between reflectivity and differential reflectivity in clouds in contrast to that found for rain. Pockets of high differential reflectivities are frequently observed in clouds; maximal values of differential reflectivity exceed 8 dB, far above the level observed in rain. The establishment of the WSR-88D network consisting of 157 polarimetric radars can be used to collect cloud data at any radar site, making the network a potentially powerful tool for climatic studies
Reductive stability evaluation of 6-azopurine photoswitches for the regulation of CKI alpha activity and circadian rhythms
Photopharmacology develops bioactive compounds whose pharmacological potency can be regulated by light. The concept relies on the introduction of molecular photoswitches, such as azobenzenes, into the structure of bioactive compounds, such as known enzyme inhibitors. Until now, the development of photocontrolled protein kinase inhibitors proved to be challenging for photopharmacology. Here, we describe a new class of heterocyclic azobenzenes based on the longdaysin scaffold, which were designed to photo-modulate the activity of casein kinase I alpha (CKI alpha) in the context of photo-regulation of circadian rhythms. Evaluation of a set of photoswitchable longdaysin derivatives allowed for better insight into the relationship between substituents and thermal stability of the cis-isomer. Furthermore, our studies on the chemical stability of the azo group in this type of heterocyclic azobenzenes showed that they undergo a fast reduction to the corresponding hydrazines in the presence of different reducing agents. Finally, we attempted light-dependent modulation of CKI alpha activity together with the accompanying modulation of cellular circadian rhythms in which CKI alpha is directly involved. Detailed structure-activity relationship (SAR) analysis revealed a new potent reduced azopurine with a circadian period lengthening effect more pronounced than that of its parent molecule, longdaysin. Altogether, the results presented here highlight the challenges in the development of light-controlled kinase inhibitors for the photomodulation of circadian rhythms and reveal key stability issues for using the emerging class of heteroaryl azobenzenes in biological applications
A phylogenomic analysis of Marek's disease virus reveals independent paths to virulence in Eurasia and North America
Virulence determines the impact a pathogen has on the fitness of its host, yet
current understanding of the evolutionary origins and causes of virulence of
many pathogens is surprisingly incomplete. Here, we explore the evolution of
Marek's disease virus (MDV), a herpesvirus commonly afflicting chickens and
rarely other avian species. The history of MDV in the 20th century represents
an important case study in the evolution of virulence. The severity of MDV
infection in chickens has been rising steadily since the adoption of intensive
farming techniques and vaccination programs in the 1950s and 1970s,
respectively. It has remained uncertain, however, which of these factors is
causally more responsible for the observed increase in virulence of
circulating viruses. We conducted a phylogenomic study to understand the
evolution of MDV in the context of dramatic changes to poultry farming and
disease control. Our analysis reveals evidence of geographical structuring of
MDV strains, with reconstructions supporting the emergence of virulent viruses
independently in North America and Eurasia. Of note, the emergence of virulent
viruses appears to coincide approximately with the introduction of
comprehensive vaccination on both continents. The time-dated phylogeny also
indicated that MDV has a mean evolutionary rate of ~1.6 × 10−5 substitutions
per site per year. An examination of gene-linked mutations did not identify a
strong association between mutational variation and virulence phenotypes,
indicating that MDV may evolve readily and rapidly under strong selective
pressures and that multiple genotypic pathways may underlie virulence
adaptation in MDV
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