Fluids in cosmology

We review the role of fluids in cosmology by first introducing them in General Relativity and then by applying them to a FRW Universe's model. We describe how relativistic and non-relativistic components evolve in the background dynamics. We also introduce scalar fields to show that they are able to yield an inflationary dynamics at very early times (inflation) and late times (quintessence). Then, we proceed to study the thermodynamical properties of the fluids and, lastly, its perturbed kinematics. We make emphasis in the constrictions of parameters by recent cosmological probes.Comment: 34 pages, 4 figures, version accepted as invited review to the book "Computational and Experimental Fluid Mechanics with Applications to Physics, Engineering and the Environment". Version 2: typos corrected and references expande

Thrombus aspiration during primary percutaneous coronary intervention is associated with reduced myocardial edema, hemorrhage, microvascular obstruction and left ventricular remodeling

<p>Abstract</p> <p>Background</p> <p>Thrombus aspiration (TA) has been shown to improve microvascular perfusion during primary percutaneous coronary intervention (PCI) for patients with ST-segment elevation myocardial infarction (STEMI). The objective of our study was to assess the relationship between TA and myocardial edema, myocardial hemorrhage, microvascular obstruction (MVO) and left ventricular remodeling in STEMI patients using cardiovascular magnetic resonance (CMR).</p> <p>Methods</p> <p>Sixty patients were enrolled post primary PCI and underwent CMR on a 1.5 T scanner at 48 hours and 6 months. Patients were retrospectively stratified into 2 groups: those that received TA (35 patients) versus that did not receive thrombus aspiration (NTA) (25 patients). Myocardial edema and myocardial hemorrhage were assessed by T2 and T2* quantification respectively. MVO was assessed via a contrast-enhanced T1-weighted inversion recovery gradient-echo sequence.</p> <p>Results</p> <p>At 48 hours, infarct segment T2 (NTA 57.9 ms vs. TA 52.1 ms, p = 0.022) was lower in the TA group. Also, infarct segment T2* was higher in the TA group (NTA 29.3 ms vs. TA 37.8 ms, p = 0.007). MVO incidence was lower in the TA group (NTA 88% vs. TA 54%, p = 0.013).</p> <p>At 6 months, left ventricular end-diastolic volume index (NTA 91.9 ml/m2 vs. TA 68.3 ml/m2, p = 0.013) and left ventricular end systolic volume index (NTA 52.1 ml/m2 vs. TA 32.4 ml/m2, p = 0.008) were lower and infarct segment systolic wall thickening was higher in the TA group (NTA 3.5% vs. TA 74.8%, p = 0.003).</p> <p>Conclusion</p> <p>TA during primary PCI is associated with reduced myocardial edema, myocardial hemorrhage, left ventricular remodeling and incidence of MVO after STEMI.</p

The Nanostructure of Myoendothelial Junctions Contributes to Signal Rectification between Endothelial and Vascular Smooth Muscle Cells

Micro-anatomical structures in tissues have potential physiological effects. In arteries and arterioles smooth muscle cells and endothelial cells are separated by the internal elastic lamina, but the two cell layers often make contact through micro protrusions called myoendothelial junctions. Cross talk between the two cell layers is important in regulating blood pressure and flow. We have used a spatiotemporal mathematical model to investigate how the myoendothelial junctions affect the information flow between the two cell layers. The geometry of the model mimics the structure of the two cell types and the myoendothelial junction. The model is implemented as a 2D axi-symmetrical model and solved using the finite element method. We have simulated diffusion of Ca2+ and IP3 between the two cell types and we show that the micro-anatomical structure of the myoendothelial junction in itself may rectify a signal between the two cell layers. The rectification is caused by the asymmetrical structure of the myoendothelial junction. Because the head of the myoendothelial junction is separated from the cell it is attached to by a narrow neck region, a signal generated in the neighboring cell can easily drive a concentration change in the head of the myoendothelial protrusion. Subsequently the signal can be amplified in the head, and activate the entire cell. In contrast, a signal in the cell from which the myoendothelial junction originates will be attenuated and delayed in the neck region as it travels into the head of the myoendothelial junction and the neighboring cell

Distinctive Gut Microbiota of Honey Bees Assessed Using Deep Sampling from Individual Worker Bees

Surveys of 16S rDNA sequences from the honey bee, Apis mellifera, have revealed the presence of eight distinctive bacterial phylotypes in intestinal tracts of adult worker bees. Because previous studies have been limited to relatively few sequences from samples pooled from multiple hosts, the extent of variation in this microbiota among individuals within and between colonies and locations has been unclear. We surveyed the gut microbiota of 40 individual workers from two sites, Arizona and Maryland USA, sampling four colonies per site. Universal primers were used to amplify regions of 16S ribosomal RNA genes, and amplicons were sequenced using 454 pyrotag methods, enabling analysis of about 330,000 bacterial reads. Over 99% of these sequences belonged to clusters for which the first blastn hits in GenBank were members of the known bee phylotypes. Four phylotypes, one within Gammaproteobacteria (corresponding to “Candidatus Gilliamella apicola”) one within Betaproteobacteria (“Candidatus Snodgrassella alvi”), and two within Lactobacillus, were present in every bee, though their frequencies varied. The same typical bacterial phylotypes were present in all colonies and at both sites. Community profiles differed significantly among colonies and between sites, mostly due to the presence in some Arizona colonies of two species of Enterobacteriaceae not retrieved previously from bees. Analysis of Sanger sequences of rRNA of the Snodgrassella and Gilliamella phylotypes revealed that single bees contain numerous distinct strains of each phylotype. Strains showed some differentiation between localities, especially for the Snodgrassella phylotype

Detection of Wolbachia in the Tick Ixodes ricinus is Due to the Presence of the Hymenoptera Endoparasitoid Ixodiphagus hookeri

The identification of micro-organisms carried by ticks is an important issue for human and animal health. In addition to their role as pathogen vectors, ticks are also the hosts for symbiotic bacteria whose impact on tick biology is poorly known. Among these, the bacterium Wolbachia pipientis has already been reported associated with Ixodes ricinus and other tick species. However, the origins of Wolbachia in ticks and their consequences on tick biology (known to be very diverse in invertebrates, ranging from nutritional symbionts in nematodes to reproductive manipulators in insects) are unknown. Here we report that the endoparasitoid wasp Ixodiphagus hookeri (Hymenoptera, Chalcidoidea, Encyrtidae) – strictly associated with ticks for their development - is infested at almost 100% prevalence by a W. pipientis strain belonging to a Wolbachia supergroup that has already been reported as associated with other hymenopteran parasitoids. In a natural population of I. ricinus that suffers high parasitism rates due to I. hookeri, we used specific PCR primers for both hymenopteran and W. pipientis gene fragments to show that all unfed tick nymphs parasitized by I. hookeri also harbored Wolbachia, while unparasitized ticks were Wolbachia-free. We demonstrated experimentally that unfed nymphs obtained from larvae exposed to I. hookeri while gorging on their vertebrate host also harbor Wolbachia. We hypothesize that previous studies that have reported W. pipientis in ticks are due to the cryptic presence of the endoparasitoid wasp I. hookeri. This association has remained hidden until now because parasitoids within ticks cannot be detected until engorgement of the nymphs brings the wasp eggs out of diapause. Finally, we discuss the consequences of this finding for our understanding of the tick microbiome, and their possible role in horizontal gene transfer among pathogenic and symbiotic bacteria

Fishery-Independent Data Reveal Negative Effect of Human Population Density on Caribbean Predatory Fish Communities

BACKGROUND: Understanding the current status of predatory fish communities, and the effects fishing has on them, is vitally important information for management. However, data are often insufficient at region-wide scales to assess the effects of extraction in coral reef ecosystems of developing nations. METHODOLOGY/PRINCIPAL FINDINGS: Here, I overcome this difficulty by using a publicly accessible, fisheries-independent database to provide a broad scale, comprehensive analysis of human impacts on predatory reef fish communities across the greater Caribbean region. Specifically, this study analyzed presence and diversity of predatory reef fishes over a gradient of human population density. Across the region, as human population density increases, presence of large-bodied fishes declines, and fish communities become dominated by a few smaller-bodied species. CONCLUSIONS/SIGNIFICANCE: Complete disappearance of several large-bodied fishes indicates ecological and local extinctions have occurred in some densely populated areas. These findings fill a fundamentally important gap in our knowledge of the ecosystem effects of artisanal fisheries in developing nations, and provide support for multiple approaches to data collection where they are commonly unavailable

Human subcortical brain asymmetries in 15,847 people worldwide reveal effects of age and sex

The two hemispheres of the human brain differ functionally and structurally. Despite over a century of research, the extent to which brain asymmetry is influenced by sex, handedness, age, and genetic factors is still controversial. Here we present the largest ever analysis of subcortical brain asymmetries, in a harmonized multi-site study using meta-analysis methods. Volumetric asymmetry of seven subcortical structures was assessed in 15,847 MRI scans from 52 datasets worldwide. There were sex differences in the asymmetry of the globus pallidus and putamen. Heritability estimates, derived from 1170 subjects belonging to 71 extended pedigrees, revealed that additive genetic factors influenced the asymmetry of these two structures and that of the hippocampus and thalamus. Handedness had no detectable effect on subcortical asymmetries, even in this unprecedented sample size, but the asymmetry of the putamen varied with age. Genetic drivers of asymmetry in the hippocampus, thalamus and basal ganglia may affect variability in human cognition, including susceptibility to psychiatric disorders

Study of 300,486 individuals identifies 148 independent genetic loci influencing general cognitive function

Correction Volume: 10, Article Number: 2068 DOI: 10.1038/s41467-019-10160-w WOS:000466339700001General cognitive function is a prominent and relatively stable human trait that is associated with many important life outcomes. We combine cognitive and genetic data from the CHARGE and COGENT consortia, and UK Biobank (total N = 300,486; age 16-102) and find 148 genome-wide significant independent loci (P <5 x 10(-8)) associated with general cognitive function. Within the novel genetic loci are variants associated with neurodegenerative and neurodevelopmental disorders, physical and psychiatric illnesses, and brain structure. Gene-based analyses find 709 genes associated with general cognitive function. Expression levels across the cortex are associated with general cognitive function. Using polygenic scores, up to 4.3% of variance in general cognitive function is predicted in independent samples. We detect significant genetic overlap between general cognitive function, reaction time, and many health variables including eyesight, hypertension, and longevity. In conclusion we identify novel genetic loci and pathways contributing to the heritability of general cognitive function.Peer reviewe

Exploration of Shared Genetic Architecture Between Subcortical Brain Volumes and Anorexia Nervosa

In MRI scans of patients with anorexia nervosa (AN), reductions in brain volume are often apparent. However, it is unknown whether such brain abnormalities are influenced by genetic determinants that partially overlap with those underlying AN. Here, we used a battery of methods (LD score regression, genetic risk scores, sign test, SNP effect concordance analysis, and Mendelian randomization) to investigate the genetic covariation between subcortical brain volumes and risk for AN based on summary measures retrieved from genome-wide association studies of regional brain volumes (ENIGMA consortium, n = 13,170) and genetic risk for AN (PGC-ED consortium, n = 14,477). Genetic correlations ranged from − 0.10 to 0.23 (all p > 0.05). There were some signs of an inverse concordance between greater thalamus volume and risk for AN (permuted p = 0.009, 95% CI: [0.005, 0.017]). A genetic variant in the vicinity of ZW10, a gene involved in cell division, and neurotransmitter and immune system relevant genes, in particular DRD2, was significantly associated with AN only after conditioning on its association with caudate volume (pFDR = 0.025). Another genetic variant linked to LRRC4C, important in axonal and synaptic development, reached significance after conditioning on hippocampal volume (pFDR = 0.021). In this comprehensive set of analyses and based on the largest available sample sizes to date, there was weak evidence for associations between risk for AN and risk for abnormal subcortical brain volumes at a global level (that is, common variant genetic architecture), but suggestive evidence for effects of single genetic markers. Highly powered multimodal brain- and disorder-related genome-wide studies are needed to further dissect the shared genetic influences on brain structure and risk for AN

Prevalence and progression of diabetic nephropathy in South Asian, white European and African Caribbean people with type 2 diabetes: A systematic review and meta-analysis

AIMS: To conduct a systematic review and meta-analysis of published observational evidence to assess the difference in the prevalence and progression of diabetic nephropathy, and the development of end-stage renal disease (ESRD) in people from three different ethnic groups with type 2 diabetes (T2DM). MATERIALS AND METHODS: Relevant studies were identified in a literature search of MEDLINE, EMBASE and reference lists of relevant studies published up to May 2018. We decided a priori that there were no differences in the prevalence and progression of diabetic nephropathy, and the development of ESRD in the three ethnicities with T2DM. Pooled relative risks of microalbuminuria by ethnicity were estimated by fitting three random effects meta-analyses models. A narrative synthesis of the nephropathy progression in the studies was carried out. The review was registered in PROSPERO (CRD42018107350). RESULTS: Thirty-two studies with data on 153 827 unique participants were eligible for inclusion in the review. The pooled prevalence ratio of microalbuminuria in South Asian compared with white European participants was 1.14 (95% confidence interval [CI] 0.99, 1.32; P = 0.065), while for African Caribbean vs South Asian participants the pooled prevalence ratio was 1.08 (95% CI 0.93, 1.24; P = 0.327). Results for renal decline were inconsistent, with preponderance towards a high rate of disease progression in South Asian compared with white participants. The estimated pooled incidence rate ratio (IRR) for ESRD was significantly higher in African Caribbean vs white European participants: 2.75 (95% CI 2.01, 3.48; P < 0.001). CONCLUSION: The results of this review did not show a significant link between ethnicity (South Asian, white European and African Caribbean) and the prevalence of microalbuminuria; however, the IRR for ESRD in African Caribbean compared with white European participants was significantly higher. Further research is needed to explore the potential non-albuminuric pathways of progression to ESRD