778 research outputs found
Are galaxies extending?
It is suggested that the recently observed size evolution of very massive
compact galaxies in the early universe can be explained, if dark matter is in
Bose Einstein condensate.
In this model the size of the dark matter halos and galaxies depends on the
correlation length of dark matter and, hence, on the the expansion of the
universe. This theory predicts that the size of the galaxies increases as the
Hubble radius of the universe even without merging, which agrees well with the
recent observational data.Comment: 5 pages, 2figs, revtex,accepted version for PL
Influence of fluid dynamic conditions on 1,3-propanediol production from glycerol by Shimwellia blattae: Carbon flux and cell response
The fluid dynamic conditions play a key role in the development and scaling up of bioprocesses. In aerobic cultures, oxygen is an essential substrate for microbial growth, production and culture maintenance; an effective gas-liquid transfer must be achieved. Changes in fluid dynamics due to stirrer speed can affect negatively to the culture, causing hydrodynamic stress (increasing shear stress) or oxidative stress (by an increase of available oxygen in the liquid phase)
High frequency volatility co-movements in cryptocurrency markets
Through the application of Diagonal BEKK and Asymmetric Diagonal BEKK methodologies to intra-day data for eight cryptocurrencies, this paper investigates not only conditional volatility dynamics of major cryptocurrencies, but also their volatility co-movements. We first provide evidence that all conditional variances are significantly affected by both previous squared errors and past conditional volatility. It is also shown that both methodologies indicate that cryptocurrency investors pay the most attention to news relating to Neo and the least attention to news relating to Dash, while shocks in OmiseGo persist the least and shocks in Bitcoin persist the most, although all of the considered cryptocurrencies possess high levels of persistence of volatility over time. We also demonstrate that the conditional covariances are significantly affected by both cross-products of past error terms and past conditional covariances, suggesting strong interdependencies between cryptocurrencies. It is also demonstrated that the Asymmetric Diagonal BEKK model is a superior choice of methodology, with our results suggesting significant asymmetric effects of positive and negative shocks in the conditional volatility of the price returns of all of our investigated cryptocurrencies, while the conditional covariances capture asymmetric effects of good and bad news accordingly. Finally, it is shown that time-varying conditional correlations exist, with our selected cryptocurrencies being strongly positively correlated, further highlighting interdependencies within cryptocurrency markets
The Main Belt Comets and ice in the Solar System
We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies
Prevalence and Determinants of Mental Health among COPD Patients in a Population-Based Sample in Spain
(1) Background: To assess the prevalence of mental disorders (depression and anxiety), psychological distress, and psychiatric medications consumption among persons suffering from COPD; to compare this prevalence with non-COPD controls and to identify which variables are associated with worse mental health. (2) Methods: This is an epidemiological case-control study. The data were obtained from the Spanish National Health Survey 2017. Subjects were classified as COPD if they reported suffering from COPD and the diagnosis of this condition had been confirmed by a physician. For each case, we selected a non-COPD control matched by sex, age, and province of residence. Conditional logistic regression was used for multivariable analysis. (3) Results: The prevalence of mental disorders (33.9% vs. 17.1%; p < 0.001), psychological distress (35.4% vs. 18.2%; p < 0.001), and psychiatric medications consumption (34.1% vs. 21.9%; p < 0.001) was higher among COPD cases compared with non-COPD controls. After controlling for possible confounding variables, such as comorbid conditions and lifestyles, using multivariable regression, the probability of reporting mental disorders (OR 1.41; 95% CI 1.10–1.82).), psychological distress (OR 1.48; 95% CI 1.12–1.91), and psychiatric medications consumption (OR 1.38 95% CI 1.11–1.71) remained associated with COPD. Among COPD cases, being a woman, poor self-perceived health, more use of health services, and active smoking increased the probability of suffering from mental disorders, psychological distress, and psychiatric medication use. Stroke and chronic pain were the comorbidities more strongly associated with these mental health variables. (4) Conclusions: COPD patients have worse mental health and higher psychological distress and consume more psychiatric medications than non-COPD matched controls. Variables associated with poorer mental health included being a woman, poor self-perceived health, use of health services, and active smoking
A review of elliptical and disc galaxy structure, and modern scaling laws
A century ago, in 1911 and 1913, Plummer and then Reynolds introduced their
models to describe the radial distribution of stars in `nebulae'. This article
reviews the progress since then, providing both an historical perspective and a
contemporary review of the stellar structure of bulges, discs and elliptical
galaxies. The quantification of galaxy nuclei, such as central mass deficits
and excess nuclear light, plus the structure of dark matter halos and cD galaxy
envelopes, are discussed. Issues pertaining to spiral galaxies including dust,
bulge-to-disc ratios, bulgeless galaxies, bars and the identification of
pseudobulges are also reviewed. An array of modern scaling relations involving
sizes, luminosities, surface brightnesses and stellar concentrations are
presented, many of which are shown to be curved. These 'redshift zero'
relations not only quantify the behavior and nature of galaxies in the Universe
today, but are the modern benchmark for evolutionary studies of galaxies,
whether based on observations, N-body-simulations or semi-analytical modelling.
For example, it is shown that some of the recently discovered compact
elliptical galaxies at 1.5 < z < 2.5 may be the bulges of modern disc galaxies.Comment: Condensed version (due to Contract) of an invited review article to
appear in "Planets, Stars and Stellar
Systems"(www.springer.com/astronomy/book/978-90-481-8818-5). 500+ references
incl. many somewhat forgotten, pioneer papers. Original submission to
Springer: 07-June-201
Chemerin and Adiponectin Contribute Reciprocally to Metabolic Syndrome
Obesity and metabolic syndrome (MetS) are considered chronic inflammatory states. Chemerin, a novel adipokine, may play an important role in linking MetS and inflammation. We investigated the association of chemerin with inflammatory markers and with characteristics of MetS in apparently healthy overweight and obese adults. We studied 92 adults; 59 men and 33 women whose average body mass index (BMI) was 28.15±5.08 kg/m2. Anthropometric parameters, insulin resistance indices, lipid profiles, and inflammatory markers including high sensitivity C-reactive protein (hsCRP), pentraxin 3 (PTX3), adiponectin, and chemerin were measured. Controlling for age, gender, and BMI, serum chemerin level was positively correlated with body fat and serum triglyceride, and negatively correlated with adiponectin and high density lipoprotein cholesterol (HDL- C), and was not correlated with altered hsCRP or PTX3 levels. Among the low, moderate and high chemerin groups, high chemerin individuals are more likely to have lower HDL-C. Conversely, individuals in the low adiponectin group are more likely to have lower HDL-C and show more MetS phenotypic traits than moderate and high adiponectin subjects. To determine the relationships of chemerin and adiponectin to MetS and its components, participants were stratified into four groups based on their chemerin and adiponectin levels (high chemerin/high adiponectin, high chemerin/low adiponectin, low chemerin/high adiponectin, or low chemerin/low adiponectin). Participants who were in the high chemerin/low adiponectin group more likely to have dyslipidemia and MetS (OR: 5.79, 95% CI:1.00–33.70) compared to the other three group. Our findings suggest that chemerin and adiponectin may reciprocally participate in the development of MetS
Population Structure as Revealed by mtDNA and Microsatellites in Northern Fur Seals, Callorhinus ursinus, throughout Their Range
Background: The northern fur seal (Callorhinus ursinus; NFS) is a widely distributed pinniped that has been shown to exhibit a high degree of philopatry to islands, breeding areas on an island, and even to specific segments of breeding areas. This level of philopatry could conceivably lead to highly genetically divergent populations. However, northern fur seals have the potential for dispersal across large distances and have experienced repeated rapid population expansions following glacial retreat and the more recent cessation of intensive harvest pressure. Methodology/Principal Findings: Using microsatellite and mitochondrial loci, we examined population structure in NFS throughout their range. We found only weak population genetic structure among breeding islands including significant FST and W ST values between eastern and western Pacific islands. Conclusions: We conclude that insufficient time since rapid population expansion events (both post glacial and following the cessation of intense harvest pressure) mixed with low levels of contemporary migration have resulted in an absence of genetic structure across the entire northern fur seal range
Dopamine D3 receptor dysfunction prevents anti-nociceptive effects of morphine in the spinal cord
Abstract
Dopamine (DA) modulates spinal reflexes, including nociceptive reflexes, in part via the D3 receptor subtype. We have previously shown that mice lacking the functional D3 receptor (D3KO) exhibit decreased paw withdrawal latencies from painful thermal stimuli. Altering the DA system in the CNS, including D1 and D3 receptor systems, reduces the ability of opioids to provide analgesia. Here, we tested if the increased pain sensitivity in D3KO might result from a modified μ-opioid receptor (MOR) function at the spinal cord level. As D1 and D3 receptor subtypes have competing cellular effects and can form heterodimers, we tested if the changes in MOR function may be mediated in D3KO through the functionally intact D1 receptor system. We assessed thermal paw withdrawal latencies in D3KO and wild type (WT) mice before and after systemic treatment with morphine, determined MOR and phosphorylated MOR (p-MOR) protein expression levels in lumbar spinal cords, and tested the functional effects of DA and MOR receptor agonists in the isolated spinal cord. In vivo, a single morphine administration (2 mg/kg) increased withdrawal latencies in WT but not D3KO, and these differential effects were mimicked in vitro, where morphine modulated spinal reflex amplitudes (SRAs) in WT but not D3KO. Total MOR protein expression levels were similar between WT and D3KO, but the ratio of pMOR/total MOR was higher in D3KO. Blocking D3 receptors in the isolated WT cord precluded morphine's inhibitory effects observed under control conditions. Lastly, we observed an increase in D1 receptor protein expression in the lumbar spinal cord of D3KO. Our data suggest that the D3 receptor modulates the MOR system in the spinal cord, and that a dysfunction of the D3 receptor can induce a morphine-resistant state. We propose that the D3KO mouse may serve as a model to study the onset of morphine resistance at the spinal cord level, the primary processing site of the nociceptive pathway
Bacterial diversity in typical abandoned multi-contaminated nonferrous metal(loid) tailings during natural attenuation
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordAbandoned nonferrous metal(loid) tailings sites are anthropogenic, and represent unique
and extreme ecological niches for microbial communities. Tailings contain elevated and toxic
content of metal(loid)s that had negative effects on local human health and regional
ecosystems. Microbial communities in these typical tailings undergoing natural attenuation
are often very poorly examined. The diversity and inferred functions of bacterial
communities were examined at seven nonferrous metal(loid) tailings sites in Guangxi (China),
which were abandoned between 3 and 31 years ago. The acidity of the tailings sites rose over
31 years of site inactivity. Desulfurivibrio, which were always coupled with sulfur/sulfide
oxidation to dissimilate the reduction of nitrate/nitrite, were specific in tailings with 3 years
abandonment. However, genus beneficial to plant growth (Rhizobium), and iron/sulfur-
oxidizing bacteria and metal(loid)-related genera (Acidiferrobacter and Acidithiobacillus)
were specific within tailings abandoned for 23 years or more. The increased abundance of
acid-generating iron/sulfur-oxidizing and metal(loid)-related bacteria and specific bacterial
communities during the natural attenuation could provide new insights for understanding
microbial ecosystem functioning in mine tailings. OTUs related to Sulfuriferula, Bacillus,
Sulfurifustis, Gaiella, and Thiobacillus genera were the main contributors differentiating the
bacterial communities between the different tailing sites. Multiple correlation analyses
between bacterial communities and geochemical parameters indicated that pH, TOC, TN, As,
Pb, and Cu were the main drivers influencing the bacterial community structures. PICRUSt
functional exploration revealed that the main functions were related to DNA repair and
recombination, important functions for bacterial adaptation to cope with the multi-
contamination of tailings. Such information provides new insights to guide future
metagenomic studies for the identification of key functions beyond metal-
transformation/resistance. As well, our results offers novel outlooks for the management of
bacterial communities during natural attenuation of multi-contaminated nonferrous metal(loid)
tailings sites.International Key Project from National Natural Science Foundation of ChinaProjects of Natural Science Foundation of ChinaPublic welfare project of Chinese Ministry of Environmental Protectionnternational key project of Ministry of Science and Technology of ChinaS2016G2135Centre National de la Recherche ScientifiqueRoyal Society Newton Mobility GrantNational Natural Science Foundation International Joint collaboration China-Swede
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