208 research outputs found
The internal Faraday screen of Sagittarius A*
We report on 85-101 GHz light curves of the Galactic Center supermassive black hole, Sagittarius A* (Sgr A*), observed in April 2017 with the Atacama Large Millimeter /submillimeter Array (ALMA). This study of high-cadence full-Stokes data provides new measurements of the fractional linear polarization at a 1-2% level resolved in 4 s time segments, and stringent upper limits on the fractional circular polarization at 0.3%. We compare these findings to ALMA light curves of Sgr A* at 212-230 GHz observed three days later, characterizing a steep depolarization of the source at frequencies below about 150 GHz. We obtain time-dependent rotation measure (RM) values, with the mean RM at 85-101 GHz being a factor of two lower than that at 212-230 GHz. Together with the rapid temporal variability of the RM and its di fferent statistical characteristics in both frequency bands, these results indicate that the Faraday screen in Sgr A* is largely internal, with about half of the Faraday rotation taking place inside the inner 10 gravitational radii, contrary to the common external Faraday screen assumption. We then demonstrate how this observation can be reconciled with theoretical models of radiatively ine fficient accretion flows for a reasonable set of physical parameters. Comparisons with numerical general relativistic magnetohydrodynamic simulations suggest that the innermost part of the accretion flow in Sgr A* is much less variable than these models predict; in particular, the observed magnetic field structure appears to be coherent and persistent
Sink or swim? Modernization of mussel farming methods may negatively impact established seabird communities
Marine aquaculture is the fastest growing sector of global food production and is projected to increase to meet future demand. Expansion and modernization of cultivation methods are needed to reach this target but a cost-benefit evaluation for biodiversity conservation is required to achieve sustainable aquaculture practices. We assess drivers of avian richness and abundance in a long-established seabird community present in a series of longline mussel farms in Italy and in response to a recent modernization process in the farming methodology. Over 2 years (24 surveys) we detected a remarkable diversity (15 species in 5 families) and abundance (n = 5858) of birds, of which 40% (n = 6) are regarded as species of international conservation importance. Our models highlighted that the strongest driver explaining variation in abundance and richness across sites was the type of buoy and the associated cultivation method applied. The older and fast-declining double headrope design, offered greater stability for birds to rest. Conversely, the newer and mechanizable single headrope design dominant method in our study site and projected to replace the older system, was unsuitable for birds. Our findings confirm the function of mussel farms as a sort of marine protected area where low anthropogenic disturbance, higher prey availability and suitable artificial structures promote the establishment of seabird communities with minimal impacts on harvest. However, we suggest that potential modernization of farming methods, important to meet future human demand, needs to be carefully assessed and compensated for, particularly where long-established seabird communities have formed in response to such practices
Particle Swarm and Quantum Particle Swarm Optimization Applied to DS/CDMA Multiuser Detection
Abstract
Serum methylarginines and spirometry-measured lung function in older adults
Rationale: Methylarginines are endogenous nitric oxide synthase inhibitors that have been implicated in animal models of lung disease but have not previously been examined for their association with spirometric measures of lung function in humans.
Objectives: This study measured serum concentrations of asymmetric and symmetric dimethylarginine in a representative sample of older community-dwelling adults and determined their association with spirometric lung function measures.
Methods: Data on clinical, lifestyle, and demographic characteristics, methylated arginines, and L-arginine (measured using LC-MS/MS) were collected from a population-based sample of older Australian adults from the Hunter Community Study.
The five key lung function measures included as outcomes were Forced Expiratory Volume in 1 second, Forced Vital Capacity, Forced Expiratory Volume in 1 second to Forced Vital Capacity ratio, Percent Predicted Forced Expiratory Volume in 1 second, and Percent Predicted Forced Vital Capacity.
Measurements and Main Results: In adjusted analyses there were statistically significant independent associations between a) higher asymmetric dimethylarginine, lower Forced Expiratory Volume in 1 second and lower Forced Vital Capacity; and b) lower L-arginine/asymmetric dimethylarginine ratio, lower Forced Expiratory Volume in 1 second, lower Percent Predicted Forced Expiratory Volume in 1 second and lower Percent Predicted Forced Vital Capacity. By contrast, no significant associations were observed between symmetric dimethylarginine and lung function.
Conclusions: After adjusting for clinical, demographic, biochemical, and pharmacological confounders, higher serum asymmetric dimethylarginine was independently associated with a reduction in key measures of lung function. Further research is needed to determine if methylarginines predict the decline in lung function
Efecto de la etapa de levante sobre la producción y reproducción en codornices japónicas (Coturnix coturnix japonica) de postura
The aim of this study was to evaluate the productive performance of laying quails (Coturnix coturnix japonica). The study was carried out at the poultry farm of the La Molina National Agrarian University in Lima, Peru. In total, 1296 quail distributed in 96 females and 48 males of three ages (45, 52 and 59 days) with 130, 140 and 150 g of body weight, respectively, at the beginning of the laying were used. A random block design with a 32 factorial arrangement was used, taking as factors age and weight at the beginning of laying and as a block the weeks of laying (8, 11 and 17). The highest egg mass (10.72 ± 0.41 g/day/bird) was obtained when the quails started laying with 150 g of live weight.El objetivo de la investigación fue evaluar el rendimiento productivo de codornices (Coturnix coturnix japonica) de postura. El estudio se realizó en la granja de aves de la Universidad Nacional Agraria La Molina en Lima, Perú. Se utilizaron 1296 codornices distribuidas en 96 hembras y 48 machos de tres edades (45, 52 y 59 días) con 130, 140 y 150 g de peso al inicio de la postura, respectivamente. Se empleó un diseño de bloques aleatorios con arreglo factorial 32 teniendo como factores edad y peso al inicio de postura y como bloque a las semanas de postura (8, 11 y 17). Las mejores conversiones alimenticias fueron de 3.67±0.36 y de 3.68±0.35, sin diferencias estadísticas entre ellas, y se obtuvieron cuando las aves iniciaron su postura con pesos de 130 y 140 g, respectivamente. La mayor masa de huevos (10.72±0.41 g/día/ave) se obtuvo cuando las aves iniciaron su postura con 150 g de peso vivo
Calibration of ALMA as a phased array: ALMA observations during the 2017 VLBI campaign
We present a detailed description of the special procedures for calibration
and quality assurance of Atacama Large Millimeter/submillimeter Array (ALMA)
observations in Very Long Baseline Interferometry (VLBI) mode. These procedures
are required to turn the phased ALMA array into a fully calibrated VLBI
station. As an illustration of these methodologies, we present
full-polarization observations carried out with ALMA as a phased array at 3mm
(Band 3) and 1.3mm (Band 6) as part of Cycle-4. These are the first VLBI
science observations conducted with ALMA and were obtained during a 2017 VLBI
campaign in concert with other telescopes worldwide as part of the Global
mm-VLBI Array (GMVA, April 1-3) and the Event Horizon Telescope (EHT, April
5-11) in ALMA Bands 3 and 6, respectively.Comment: 39 pages, 20 figures, 10 tables, accepted by PAS
Phenotypic and Functional Properties of Helios+ Regulatory T Cells
Helios, an Ikaros family transcription factor, is preferentially expressed at the mRNA and protein level in regulatory T cells. Helios expression previously appeared to be restricted to thymic-derived Treg. Consistent with recent data, we show here that Helios expression is inducible in vitro under certain conditions. To understand phenotypic and functional differences between Helios+ and Helios− Treg, we profiled cell-surface markers of FoxP3+ Treg using unmanipulated splenocytes. We found that CD103 and GITR are expressed at high levels on a subset of Helios+ Treg and that a Helios+ Treg population could be significantly enriched by FACS sorting using these two markers. Quantitative real-time PCR (qPCR) analysis revealed increased TGF-β message in Helios+ Treg, consistent with the possibility that this population possesses enhanced regulatory potential. In tumor-bearing mice, we found that Helios+ Treg were relatively over-represented in the tumor-mass, and BrdU studies showed that, in vivo, Helios+ Treg proliferated more than Helios− Treg. We hypothesized that Helios-enriched Treg might exert increased suppressive effects. Using in vitro suppression assays, we show that Treg function correlates with the absolute number of Helios+ cells in culture. Taken together, these data show that Helios+ Treg represent a functional subset with associated CD103 and GITR expression
The Genomic and Immune Landscapes of Lethal Metastatic Breast Cancer.
The detailed molecular characterization of lethal cancers is a prerequisite to understanding resistance to therapy and escape from cancer immunoediting. We performed extensive multi-platform profiling of multi-regional metastases in autopsies from 10 patients with therapy-resistant breast cancer. The integrated genomic and immune landscapes show that metastases propagate and evolve as communities of clones, reveal their predicted neo-antigen landscapes, and show that they can accumulate HLA loss of heterozygosity (LOH). The data further identify variable tumor microenvironments and reveal, through analyses of T cell receptor repertoires, that adaptive immune responses appear to co-evolve with the metastatic genomes. These findings reveal in fine detail the landscapes of lethal metastatic breast cancer.CRUK
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