837 research outputs found
A Link Between the Semi-Major Axis of Extrasolar Gas Giant Planets and Stellar Metallicity
The fact that most extrasolar planets found to date are orbiting metal-rich
stars lends credence to the core accretion mechanism of gas giant planet
formation over its competitor, the disc instability mechanism. However, the
core accretion mechanism is not refined to the point of explaining orbital
parameters such as their unexpected semi-major axes and eccentricities. We
propose a model, which correlates the metallicity of the host star with the
original semi-major axis of its most massive planet, prior to migration,
considering that the core accretion scenario governs giant gas planet
formation. The model predicts that the optimum regions for planetary formation
shift inward as stellar metallicity decreases, providing an explanation for the
observed absence of long period planets in metal-poor stars. We compare our
predictions with the available data on extrasolar planets for stars with masses
similar to the mass of the Sun. A fitting procedure produces an estimate of
what we define as the Zero Age Planetary Orbit (ZAPO) curve as a function of
the metallicity of the star. The model also hints that the lack of planets
circling metal-poor stars may be partly caused by an enhanced destruction
probability during the migration process, since the planets lie initially
closer to the central stars.Comment: Nature of the replacement: According to recent simulations, the
temperature profile, T, is more adequately reproduced by beta = 1 rather than
beta = 2. We have introduced a distance scale factor that solves the very
fast drop of T for low metallicity and introduces naturally the inferior
distance limit of our ZAPO. Under this modification all the fitting process
was altere
A Bulk-Parallel Priority Queue in External Memory with STXXL
We propose the design and an implementation of a bulk-parallel external
memory priority queue to take advantage of both shared-memory parallelism and
high external memory transfer speeds to parallel disks. To achieve higher
performance by decoupling item insertions and extractions, we offer two
parallelization interfaces: one using "bulk" sequences, the other by defining
"limit" items. In the design, we discuss how to parallelize insertions using
multiple heaps, and how to calculate a dynamic prediction sequence to prefetch
blocks and apply parallel multiway merge for extraction. Our experimental
results show that in the selected benchmarks the priority queue reaches 75% of
the full parallel I/O bandwidth of rotational disks and and 65% of SSDs, or the
speed of sorting in external memory when bounded by computation.Comment: extended version of SEA'15 conference pape
Rumen-protected choline supplementation in periparturient dairy goats: effects on liver and mammary gland
The current study investigated the effects of supplementing rumen-protected choline (RPC) on metabolic profile, selected liver constituents and transcript levels of selected enzymes, transcription factors and nuclear receptors involved in mammary lipid metabolism in dairy goats. Eight healthy lactating goats were studied: four received no choline supplementation (CTR group) and four received 4 g RPC chloride/day (RPC group). The treatment was administered individually starting 4 weeks before expected kidding and continuing for 4 weeks after parturition. In the first month of lactation, milk yield and composition were measured weekly. On days 7, 14, 21 and 27 of lactation, blood samples were collected and analysed for glucose, β-hydroxybutyrate, non-esterified fatty acids and cholesterol. On day 28 of lactation, samples of liver and mammary gland tissue were obtained. Liver tissue was analysed for total lipid and DNA content; mammary tissue was analysed for transcripts of lipoprotein lipase (LPL), fatty acid synthase (FAS), sterol regulatory binding proteins 1 and 2, peroxisome proliferator-activated receptor γ and liver X receptor α. Milk yield was very similar in the two groups, but RPC goats had lower (P<0·05) plasma β-hydroxybutyrate. The total lipid content of liver was unaffected (P=0·890), but the total lipid/DNA ratio was lower (both P<0·05) in RPC than CTR animals. Choline had no effect on the expression of the mammary gland transcripts involved in lipid metabolism. The current plasma and liver data indicate that choline has a positive effect on liver lipid metabolism, whereas it appears to have little effect on transcript levels in mammary gland of various proteins involved in lipid metabolism. Nevertheless, the current results were obtained from a limited number of animals, and choline requirement and function in lactating dairy ruminants deserve further investigatio
Multivariate image analysis for the rapid detection of residues from packaging remnants in former foodstuff products (FFPs)–a feasibility study
From a circular economy perspective, feeding livestock with food leftovers or former foodstuff products (FFPs) could be an effective option aimed at exploiting food leftover resources and reducing food losses. FFPs are valuable energy sources, characterised by a beneficial starch/sugar content, and also fats. However, besides these nutritional aspects, safety is a key concern given that FFPs are generally derived from packaged food. Packaging materials, such as plastics and paper, are not accepted as a feed ingredient which means that residues should be rigorously avoided. A sensitive and objective detection method is thus essential for an accurate risk evaluation throughout the former food production chain. To this end, former food samples were collected in processing plants of two different European countries and subjected to multivariate analysis of red, green, and blue (RGB) microscopic images, in order to evaluate the possible application of this non-destructive technique for the rapid detection of residual particles from packaging materials. Multivariate Image Analysis (MIA) was performed on single images at the pixel level, which essentially consisted in an exploratory analysis of the image data by means of Principal Component Analysis, which highlighted the differences between packaging and foodstuff particles, based on their colour. The whole dataset of images was then analysed by means of a multivariate data dimensionality reduction method known as the colourgrams approach, which identified clusters of images sharing similar features and also highlighted outlier images due to the presence of packaging particles. The results obtained in this feasibility study demonstrated that MIA is a promising tool for a rapid automated method for detecting particles of packaging materials in FFPs
Concentration-Dependent Effects of N-3 Long-Chain Fatty Acids on Na,K-ATPase Activity in Human Endothelial Cells
N-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) seem to prevent endothelial dysfunction, a crucial step in atherogenesis, by modulating the levels of vasoactive molecules and by influencing Na,K-ATPase activity of vascular myocytes. The activity of endothelial Na,K-ATPase controls the ionic homeostasis of the neighboring cells, as well as cell function. However, controversy exists with respect to the vascular protective effect of EPA and DHA. We argue that this dispute might be due to the use of different concentrations of EPA and DHA in different studies. Therefore, this study was designed to define an optimal concentration of EPA and DHA to investigate endothelial function. For this purpose, human endothelial cells were exposed for 24 h to different concentrations of DHA or EPA (0\u201320 \u3bcM) to study membrane fluidity, peroxidation potential and Na,K-ATPase activity. EPA and DHA were linearly incorporated and this incorporation was mirrored by the linear increase of unsaturation index, membrane fluidity, and peroxidation potential. Na,K-ATPase activity peaked at 3.75 \u3bcM of EPA and DHA and then gradually decreased. It is noteworthy that DHA effects were always more pronounced than EPA. Concluding, low concentrations of EPA and DHA minimize peroxidation sensitivity and optimize Na,K-ATPase activity
CEREBROSPINAL FLUID DRAINAGE DEVICES: EXPERIMENTAL CARACTERIZATION
Hydrocephalus is a pathophysiology due to the excess of cerebrospinal fluid in the brain ventricles and it can be caused by congenital defects, brain abnormalities, tumors, inflammations, infections, intracranial hemorrhage and others. Hydrocephalus can be followed by significant rise of intraventricular pressure due to the excess of production of cerebrospinalfluid over the absorption, resulting in a weakening of intellectual functions, serious neurological damage (decreased movement, sensation and functions), critical physical disabilities and even death. A procedure for treatment involves the placement of a ventricular catheter into the cerebral ventricles to divert/drain the cerebrospinal fluid flow to a bag outside of the patient body – provisory treatment known as external ventricular drainage (EVD). Another option is the permanent treatment, internal ventricular drainage (IVD), promoting the cerebrospinal fluid drainage to other body cavity, being more commonly the abdominal cavity. In both cases, EVD and IVD, it is necessary to use of some type of neurological valve in order to control the flow of cerebrospinal fluid. In the present work is proposed an experimental procedure to test the hydrodynamic behavior of a complete drainage system, or parts of them, in order to verify its performance when subjected to pressure gradients found in the human body. Results show that the method is well adapted to quantify the pressure drop in neurological systems
The Political Legacy of Entertainment TV
We study the political impact of commercial television in Italy exploiting the staggered introduction of Berlusconi's private TV network, Mediaset, in the early 1980s. We find that individuals with early access to Mediaset all-entertainment content were more likely to vote for Berlusconi's party in 1994, when he first ran for office. The effect persists for five elections and is driven by heavy TV viewers, namely the very young and the elderly. Regarding possible mechanisms, we find that individuals exposed to entertainment TV as children were less cognitively sophisticated and civic-minded as adults, and ultimately more vulnerable to Berlusconi's populist rhetoric.
© 2019 AE
Counteracting the Common Shwachman–Diamond Syndrome-Causing SBDS c.258+2T>C Mutation by RNA Therapeutics and Base/Prime Editing
Shwachman-Diamond syndrome (SDS) represents one of the most common inherited bone marrow failure syndromes and is mainly caused by SBDS gene mutations. Only supportive treatments are available, with hematopoietic cell transplantation required when marrow failure occurs. Among all causative mutations, the SBDS c.258+2T>C variant at the 5 ' splice site (ss) of exon 2 is one of the most frequent. Here, we investigated the molecular mechanisms underlying aberrant SBDS splicing and showed that SBDS exon 2 is dense in splicing regulatory elements and cryptic splice sites, complicating proper 5 ' ss selection. Studies ex vivo and in vitro demonstrated that the mutation alters splicing, but it is also compatible with tiny amounts of correct transcripts, which would explain the survival of SDS patients. Moreover, for the first time for SDS, we explored a panel of correction approaches at the RNA and DNA levels and provided experimental evidence that the mutation effect can be partially counteracted by engineered U1snRNA, trans-splicing, and base/prime editors, ultimately leading to correctly spliced transcripts (from barely detectable to 2.5-5.5%). Among them, we propose DNA editors that, by stably reverting the mutation and potentially conferring positive selection to bone-marrow cells, could lead to the development of an innovative SDS therapy
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