1,560 research outputs found

    Study made of large amplitude fuel sloshing

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    Study of resonant oscillations of an ideal fluid in a cylindrical tank is used to obtain a better understanding of fuel sloshing in large liquid booster. More realistic structural design criteria may be formulated when the dynamic response of the liquid in a cylindrical tank can be predicted analytically

    Do not disturb the family: roles of colony size and human disturbance in the genetic structure of lesser kestrel

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    Dispersal and philopatry are fundamental processes influencing the genetic structure and persistence of populations and might be affected by isolation and habitat perturbation. Habitat degradation induced by human activities could have detrimental consequences on genetic structure of populations. Therefore, it is crucial to understand the role of human impacts in promoting or disrupting genetic structure. Here, we conducted a genetic analysis using 12 polymorphic microsatellite markers of 70 lesser kestrels (Falco naumanni) from 10 breeding colonies of two subpopulations in Sicily (southern Italy). Genetic differentiation between the two subpopulations was negligible, and linear distances played no role in the level of genetic relatedness recorded in the two sites. Linear distances between nests also resulted in no effects on the relatedness recorded within and between colonies in the largest subpopulation. Clusters of more versus less related individuals resulted when the two-dimensional positions of colonies (i.e., latitude and longitude) were tested as predictors of genetic proximity instead of linear distances. Specifically, analyses of colony features showed colony size and human disturbance as factors negatively affecting the relatedness among chicks from different nests. Regardless of colony size, less-related individuals were born in colonies located in the core of the agricultural plain, where we quantified a higher level of human disturbance. In contrast, more related individuals were in colonies that existed in the marginal, less disturbed, agricultural area. Given the high philopatry of this species, our results are consistent with disruption of colony fidelity related to intensification of agricultural practices. We discuss the possible implications of long-term effects of genetic variability in small and disturbed colonies on fitness and population viability

    Emotional expression and coping style in female breast cancer.

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    Background: The study of the relationship of emotional status and tumor etiology has been investigated in order to elaborate a multifactorial model able to provide an answer integrating the different disciplines on cancer. The aim of this work is to investigate the knowledge on the alexithymia construct, exploring the presence of such trait in women affected by mammary carcinoma and analyzing the used coping strategies. The study has also examined personal thoughts related to event control (locus of control). Method: The Toronto Alexithymia Scale, Coping Orientation to Problems Experienced, and Locus of Control questionnaires were administered to a group of 86 women aged 31\u201355 years (mean = 43.7; SD 6.57)\u2014experimental group (N = 44): women with breast cancer diagnosed in the last 6 months; control group (N = 42): women without oncologic pathology, referred at the aforementioned institutions to undergo a breast check-up. Results: According to our hypothesis and literature data, a significant presence of alexithymic subjects (36.4% versus 2.4%; v2 = 20.9; P < 0.0001) and a tendency to adopt coping strategies not focused on the problem were reported among women with mammary carcinoma. This causes incapability to act in order to actively contrast pathology-linked stress or to lower the effects. Conclusion: Our results indicate that the tendency to repress one\u2019s emotions is associated to some general schemes of reaction to stress which, when used in a dysfunctional manner (such as the attempt to ignore how threatening an event is), are maladaptive in the end

    Extremely fast Holocene coastal landscape evolution in the Kachchh Upland (NW India): Clues from a multidisciplinary review

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    The coastal landscape of the Kachchh Upland (KU) region (NW-India) changed over the last few thousand years from a shallow marine gulf to a salty desert (1-4 meters asl). In this area, bordered to the south by the Northern Hill Range (NHR), the tectonic-climatic interaction triggered the sea level fall from +2/4 m circa (6000-2000 BP) to zero. An ancient river pattern deposited a tidally regulated delta area during the sea level fall that stopped 2000-3000 years ago due to tectonic activity and a dry climate. Deltaic-alluvial fans (DAF) in front of the NHR suggest that the KU's tectonic activity led to fast landscape evolution. We explored such drastic changes by integrating scientific information from a multidisciplinary literature review, identifying terraces and DAFs, and inferring faults through landform recognition, quantitative morphometry, and field surveys. Our interpretation, summarized in a map, provides new information on active processes along the NHR

    INVESTIGATING THE NUCLEOTIDE DIVERSITY IN THE GLUTATHIONE S-TRANSFERASE GENE FAMILY ACROSS THE TOMATO GENE POOL AND ITS SIGNIFICANCE IN CONTROLLING PLANT RESPONSE TO STRESS

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    The agricultural sector faces a significant challenge in dealing with environmental stresses, which greatly reduce crop productivity. Due to global warming and climate change, abiotic stresses are predicted to become more frequent. In this scenario, to meet a growing global demand for food, breeding crops for enhanced tolerance to harsh environments is promising. The cultivated tomato (Solanum lycopersicum L.) is one of the most important vegetable crops in the world and the genome of its wild relatives Solanum pimpinellifolium, Solanum lycopersicoides and Solanum pennellii have been sequenced and their effective tolerance to extreme environments well documented. However, knowledge about tomato genetic diversity is limited and its phenotypic significance dramatically unpredictable to make its exploitation proficient. Glutathione S-transferase (GST) genes have been identified in numerous plant species and are involved in various physiological, developmental, and stress modulation pathways. The aim of this study was to provide a comprehensive description of the GST nucleotide diversity in the tomato gene pool and contextual mining of functional significance for plant adaptability to challenging stresses. We identified 83 GST genes in Solanum lycopersicum (ITAG 4.1) and their orthologues within the wild relatives. Sequences were analyzed for their exon-intron structures, conserved protein motifs, putative subcellular locations, phylogenetic relationships and duplication events. Interaction networks, promoter and cis-regulatory elements and gene expression profiles were also identified. Phylogenetic analysis enabled grouping GST genes into ten subclasses. Furthermore, protein–protein interaction networks revealed the central role of GST genes controlling the cell redox state. A reference non redundant core collection of 75 tomato genotypes was selected from a larger collection of worldwide accessions genotyped by SSR markers. The core collection was screened for drought tolerance at the fruit set stage on the first flower truss. The leaves were assayed for gas exchange and colorimetric variations and profiled for H2O2, ascorbic acid and antioxidant capacity. The most tolerant and sensitive tomato accessions were selected. Plants were grown in lysimeters where the water supply was managed to apply two levels of soil water potential that is 10-20 kPa in the control treatment and 100-120 kPa for the drought treatment, respectively. To deepen our understanding of the regulatory mechanisms that control photo-assimilation, photo-assimilate allocation and fruit yield and quality under limited levels of available water, leaves, stems and fruit at different ripening stages were collected for RNA-seq analysis. Further bioinformatics analysis will allow us to validate the role of specific GSTs and other key genes in controlling the response of tomato plants to drought and modulating photo-assimilate allocation in sensitive and tolerant genomic backgrounds

    The immunosuppressive cytokine interleukin-4 increases the clonogenic potential of prostate stem-like cells by activation of STAT6 signalling

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    Interleukin-4 plays a critical role in the regulation of immune responses and has been detected at high levels in the tumour microenvironment of cancer patients, where concentrations correlate with the grade of malignancy. In prostate cancer, interleukin-4 has been associated with activation of the androgen receptor, increased proliferation and activation of survival pathways such as Akt and NF-κB. However, its role in therapy resistance has not yet been determined. Here we investigate the influence of interleukin-4 on primary epithelial cells from prostate cancer patients. Our data demonstrate an increase in the clonogenic potential of these cells when cultured in the presence of interleukin-4. In addition, a Phospho-Kinase Array revealed that in contrast to previously published work, signal transducer and activator of transcription6 (STAT6) is the only signalling molecule activated after interleukin-4 treatment. Using the STAT6-specific inhibitor AS1517499 we could confirm the role of STAT6 in increasing colony-forming frequency. However, clonogenic recovery assays revealed that interleukin-4 does not rescue the effects of either irradiation or docetaxel treatment. We therefore propose that although the interleukin-4/STAT6 axis does not appear to be involved in therapy resistance, it does play a crucial role in the colony-forming abilities of the basal cell population in prostate cancer. IL-4 may therefore contribute to disease relapse by providing a niche that is favourable for the clonogenic growth of prostate cancer stem cells

    Observation of a two-dimensional electron gas at the surface of annealed SrTiO3 single crystals by scanning tunneling spectroscopy

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    Scanning tunneling spectroscopy suggests the formation of a two dimensional electron gas (2DEG) on the TiO2 terminated surface of undoped SrTiO3 single crystals annealed at temperature lower than 400 {\deg}C in ultra high vacuum conditions. Low energy electron diffraction indicates that the 2D metallic SrTiO3 surface is not structurally reconstructed, suggesting that non-ordered oxygen vacancies created in the annealing process introduce carriers leading to an electronic reconstruction. The experimental results are interpreted in a frame of competition between oxygen diffusion from the bulk to the surface and oxygen loss from the surface itself.Comment: 9 pages, 3 figures, submitted to Physical Review

    XIPE: the X-ray imaging polarimetry explorer

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    Abstract X-ray polarimetry, sometimes alone, and sometimes coupled to spectral and temporal variability measurements and to imaging, allows a wealth of physical phenomena in astrophysics to be studied. X-ray polarimetry investigates the acceleration process, for example, including those typical of magnetic reconnection in solar flares, but also emission in the strong magnetic fields of neutron stars and white dwarfs. It detects scattering in asymmetric structures such as accretion disks and columns, and in the so-called molecular torus and ionization cones. In addition, it allows fundamental physics in regimes of gravity and of magnetic field intensity not accessible to experiments on the Earth to be probed. Finally, models that describe fundamental interactions (e.g. quantum gravity and the extension of the Standard Model) can be tested. We describe in this paper the X-ray Imaging Polarimetry Explorer (XIPE), proposed in June 2012 to the first ESA call for a small mission with a launch in 2017. The proposal was, unfortunately, not selected. To be compliant with this schedule, we designed the payload mostly with existing items. The XIPE proposal takes advantage of the completed phase A of POLARIX for an ASI small mission program that was cancelled, but is different in many aspects: the detectors, the presence of a solar flare polarimeter and photometer and the use of a light platform derived by a mass production for a cluster of satellites. XIPE is composed of two out of the three existing JET-X telescopes with two Gas Pixel Detectors (GPD) filled with a He-DME mixture at their focus. Two additional GPDs filled with a 3-bar Ar-DME mixture always face the Sun to detect polarization from solar flares. The Minimum Detectable Polarization of a 1 mCrab source reaches 14 % in the 2-10 keV band in 105 s for pointed observations, and 0.6 % for an X10 class solar flare in the 15-35 keV energy band. The imaging capability is 24 arcsec Half Energy Width (HEW) in a Field of View of 14.7 arcmin × 14.7 arcmin. The spectral resolution is 20 % at 6 keV and the time resolution is 8 mus. The imaging capabilities of the JET-X optics and of the GPD have been demonstrated by a recent calibration campaign at PANTER X-ray test facility of the Max-Planck-Institut für extraterrestrische Physik (MPE, Germany). XIPE takes advantage of a low-earth equatorial orbit with Malindi as down-link station and of a Mission Operation Center (MOC) at INPE (Brazil). The data policy is organized with a Core Program that comprises three months of Science Verification Phase and 25 % of net observing time in the following 2 years. A competitive Guest Observer program covers the remaining 75 % of the net observing time

    The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years

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    In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented by Sloan Digital Sky Survey imaging and spectroscopy. We observed striking differences in the morphological, colour, spectral, and stellar mass properties of the BCGs/MMCGs in the two samples. High-redshift BCGs/MMCGs were, in many cases, star-forming, late-type galaxies, with blue broad-band colours, properties largely absent amongst the low-redshift BCGs/MMCGs. The stellar mass of BCGs was found to increase by an average factor of 2.51 ± 0.71 from z ∼ 0.9 to z ∼ 0.1. Through this and other comparisons, we conclude that a combination of major merging (mainly wet or mixed) and in situ star formation are the main mechanisms which build stellar mass in BCGs/MMCGs. The stellar mass growth of the BCGs/MMCGs also appears to grow in lockstep with both the stellar baryonic and total mass of the cluster. Additionally, BCGs/MMCGs were found to grow in size, on average, a factor of ∼3, while their average Sérsic index increased by ∼0.45 from z ∼ 0.9 to z ∼ 0.1, also supporting a scenario involving major merging, though some adiabatic expansion is required. These observational results are compared to both models and simulations to further explore the implications on processes which shape and evolve BCGs/MMCGs over the past ∼7 Gyr

    Planck intermediate results. XLIX. Parity-violation constraints from polarization data

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    Parity-violating extensions of the standard electromagnetic theory cause in vacuo rotation of the plane of polarization of propagating photons. This effect, also known as cosmic birefringence, has an impact on the cosmic microwave background (CMB) anisotropy angular power spectra, producing non-vanishing T–B and E–B correlations that are otherwise null when parity is a symmetry. Here we present new constraints on an isotropic rotation, parametrized by the angle α, derived from Planck 2015 CMB polarization data. To increase the robustness of our analyses, we employ two complementary approaches, in harmonic space and in map space, the latter based on a peak stacking technique. The two approaches provide estimates for α that are in agreement within statistical uncertainties and are very stable against several consistency tests.Considering the T–B and E–B information jointly, we find from the harmonic analysis and from the stacking approach. These constraints are compatible with no parity violation and are dominated by the systematic uncertainty in the orientation of Planck’s polarization-sensitive bolometers
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