930 research outputs found
The non-universality of the low-mass end of the IMF is robust against the choice of SSP model
We perform a direct comparison of two state-of-the art single stellar
population (SSP) models that have been used to demonstrate the non-universality
of the low-mass end of the Initial Mass Function (IMF) slope. The two public
versions of the SSP models are restricted to either solar abundance patterns or
solar metallicity, too restrictive if one aims to disentangle elemental
enhancements, metallicity changes and IMF variations in massive early-type
galaxies (ETGs) with star formation histories different from the solar
neighborhood. We define response functions (to metallicity and
\alpha-abundance) to extend the parameter space of each set of models. We
compare these extended models with a sample of Sloan Digital Sky Survey (SDSS)
ETGs spectra with varying velocity dispersions. We measure equivalent widths of
optical IMF-sensitive stellar features to examine the effect of the underlying
model assumptions and ingredients, such as stellar libraries or isochrones, on
the inference of the IMF slope down to ~0.1 solar masses. We demonstrate that
the steepening of the low-mass end of the Initial Mass Function (IMF) based on
a non-degenerate set of spectroscopic optical indicators is robust against the
choice of the stellar population model. Although the models agree in a relative
sense (i.e. both imply more bottom-heavy IMFs for more massive systems), we
find non-negligible differences on the absolute values of the IMF slope
inferred at each velocity dispersion by using the two different models. In
particular, we find large inconsistency in the quantitative predictions of IMF
slope variations and abundance patterns when sodium lines are used. We
investigate the possible reasons for these inconsistencies.Comment: 16 pages, 9 figures, 2 tables, accepted for publication on Ap
Adoption des Technologies Agro-Ăcologiques : Perception et PrĂ©fĂ©rence des Agriculteurs de la Zone CotonniĂšre du BĂ©nin
La promotion des pratiques agro-Ă©cologiques est devenue lâune des options favorables pouvant contribuer durablement Ă la gestion des sols et Ă la prĂ©servation des Ă©cosystĂšmes pour la sĂ©curitĂ© alimentaire et nutritionnelle dans le contexte actuel des changements climatiques. Cette Ă©tude vise Ă analyser la perception et la prĂ©fĂ©rence des producteurs sur les pratiques agroĂ©cologiques innovantes promues dans le cadre du « projet dâappui Ă la Transition Agro-Ă©cologique dans les Zones CotonniĂšres du BĂ©nin (TAZCO) ». Pour faciliter lâadoption de telles technologies par les producteurs, il faut agir sur les dĂ©terminants qui leurs sont favorables. La perception Ă©tant un dĂ©terminant de lâadoption et la prĂ©sente Ă©tude a Ă©tĂ© rĂ©alisĂ©e pour proposer par commune, au moins cinq technologies pour lesquelles les producteurs ont une bonne prĂ©fĂ©rence. Cette Ă©tude a Ă©tĂ© conduite dans la zone dâintervention du TAZCO, constituĂ©e de Banikoara, Kandi, Oussa-PĂ©hunco, Parakou et Savalou. En utilisant la mĂ©thode dâĂ©chantillonnage alĂ©atoire avec le paramĂštre de disponibilitĂ© des producteurs impliquĂ©s, 282 producteurs ont Ă©tĂ© enquĂȘtĂ©s lors de la collecte des donnĂ©es parmi les 300 impliquĂ©s dans la phase pilote du projet. Les donnĂ©es ont Ă©tĂ© collectĂ©es Ă lâaide dâun questionnaire structurĂ©, dĂ©veloppĂ© sur smartphones avec lâapplication ââKoBocollectââ. Ces donnĂ©es ont Ă©tĂ© analysĂ©es Ă lâaide de mĂ©thode multicritĂšre dâaide Ă la dĂ©cision et une liste de cinq technologies variant dâune zone Ă lâautre a Ă©tĂ© Ă©tablie. LâĂ©tude a montrĂ© que les technologies de la famille « Gestion IntĂ©grĂ©e de la FertilitĂ© du Sol » et « Gestion IntĂ©grĂ©e Agriculture-Elevage » viennent en tĂȘte dans la majoritĂ© des zones dâintervention du TAZCO.
Agro-ecological practices promotion become one of the favorable options that can sustainably contribute to soil management and ecosystem preservation for food and nutrition security under climate change context. This study aims to analyze producersâ perception and preference on agro-ecological practices promoted by TAZCO project (Agro-ecological Transition in Benin Cotton Areas). To facilitate promoted technologies adoption by producers, it is necessary to act on determinants affecting thempositively. Based on the fact that perception is one of the technology adoption determinants, the study was carried out to suggesting each of the municipalities involved in the study at least five technologies which received producersâ favorable preference. The study was conducted in the area covered by TAZCO activities (Banikoara, Kandi, Oussa-PĂ©hunco, Parakou and Savalou). Using the random sampling method with producers involvedâs availability parameter, 282 producers over to the 300 involved in the pilot project were interwied during data collecting. Data were collected using a structured questionnaire developed under ''Kobocollect'' application on smartphones. The multi-criteria decision-support method was used to analyze collected data and a list of five technologies varying from one zone to another was established. The study showed that the technologies named "IntegratedManagement of Soil Fertility" and "Integrated Management Agriculture-Livestock" revealed to be the most important in the majority of TAZCO intervention areas
The SWELLS survey. IV. Precision measurements of the stellar and dark matter distributions in a spiral lens galaxy
We construct a fully self-consistent mass model for the lens galaxy J2141 at
z=0.14, and use it to improve on previous studies by modelling its
gravitational lensing effect, gas rotation curve and stellar kinematics
simultaneously. We adopt a very flexible axisymmetric mass model constituted by
a generalized NFW dark matter halo and a stellar mass distribution obtained by
deprojecting the MGE fit to the high-resolution K'-band LGSAO imaging data of
the galaxy, with the (spatially constant) M/L ratio as a free parameter. We
model the stellar kinematics by solving the anisotropic Jeans equations. We
find that the inner logarithmic slope of the dark halo is weakly constrained
(gamma = 0.82^{+0.65}_{-0.54}), and consistent with an unmodified NFW profile.
We infer the galaxy to have (i) a dark matter fraction within 2.2 disk radii of
0.28^{+0.15}_{-0.10}, independent of the galaxy stellar population, implying a
maximal disk for J2141; (ii) an apparently uncontracted dark matter halo, with
concentration c_{-2} = 7.7_{-2.5}^{+4.2} and virial velocity v_{vir} =
242_{-39}^{+44} km/s, consistent with LCDM predictions; (iii) a slightly oblate
halo (q_h = 0.75^{+0.27}_{-0.16}), consistent with predictions from
baryon-affected models. Comparing the stellar mass inferred from the combined
analysis (log_{10} Mstar/Msun = 11.12_{-0.09}^{+0.05}) with that inferred from
SPS modelling of the galaxies colours, and accounting for a cold gas fraction
of 20+/-10%, we determine a preference for a Chabrier IMF over Salpeter IMF by
a Bayes factor of 5.7 (substantial evidence). We infer a value beta_{z} = 1 -
sigma^2_{z}/sigma^2_{R} = 0.43_{-0.11}^{+0.08} for the orbital anisotropy
parameter in the meridional plane, in agreement with most studies of local disk
galaxies, and ruling out at 99% CL that the dynamics of this system can be
described by a two-integral distribution function. [Abridged]Comment: Accepted for publication in MNRAS. 17 pages, 9 figure
The P2Y12 receptor induces platelet aggregation through weak activation of the αIIbÎČ3 integrin â a phosphoinositide 3-kinase-dependent mechanism
AbstractHigh concentrations of adenosine-5âČ-diphosphate ADP are able to induce partial aggregation without shape change of P2Y1 receptor-deficient mouse platelets through activation of the P2Y12 receptor. In the present work we studied the transduction pathways selectively involved in this phenomenon. Flow cytometric analyses using R-phycoerythrin-conjugated JON/A antibody (JON/A-PE), an antibody which recognizes activated mouse αIIbÎČ3 integrin, revealed a low level activation of αIIbÎČ3 in P2Y1 receptor-deficient platelets in response to 100 ÎŒM ADP or 1 ÎŒM 2MeS-ADP. Adrenaline induced no such activation but strongly potentiated the effect of ADP in a dose-dependent manner. Global phosphorylation of 32P-labeled platelets showed that P2Y12-mediated aggregation was not accompanied by an increase in the phosphorylation of myosin light chain (P20) or pleckstrin (P47) and was not affected by the protein kinase C (PKC) inhibitor staurosporine. On the other hand, two unrelated phosphoinositide 3-kinase inhibitors, wortmannin and LY294002, inhibited this aggregation. Our results indicate that (i) the P2Y12 receptor is able to trigger a P2Y1 receptor-independent inside-out signal leading to αIIbÎČ3 integrin activation and platelet aggregation, (ii) ADP and adrenaline use different signaling pathways which synergize to activate the αIIbÎČ3 integrin, and (iii) the transduction pathway triggered by the P2Y12 receptor is independent of PKC but dependent on phosphoinositide 3-kinase
Diffraction in low-energy electron scattering from DNA: bridging gas phase and solid state theory
Using high-quality gas phase electron scattering calculations and multiple
scattering theory, we attempt to gain insights on the radiation damage to DNA
induced by secondary low-energy electrons in the condensed phase, and to bridge
the existing gap with the gas phase theory and experiments. The origin of
different resonant features (arising from single molecules or diffraction) is
discussed and the calculations are compared to existing experiments in thin
films.Comment: 40 pages preprint, 12 figures, submitted to J. Chem. Phy
New Exact Solutions of a Generalized Shallow Water Wave Equation
In this work an extended elliptic function method is proposed and applied to
the generalized shallow water wave equation. We systematically investigate to
classify new exact travelling wave solutions expressible in terms of
quasi-periodic elliptic integral function and doubly-periodic Jacobian elliptic
functions. The derived new solutions include rational, periodic, singular and
solitary wave solutions. An interesting comparison with the canonical procedure
is provided. In some cases the obtained elliptic solution has singularity at
certain region in the whole space. For such solutions we have computed the
effective region where the obtained solution is free from such a singularity.Comment: A discussion about singularity and some references are added. To
appear in Physica Script
Disturbance of approach-avoidance behaviors in non-human primates by stimulation of the limbic territories of basal ganglia and anterior insula
The basal ganglia (BG) are involved in motivation and goalâdirected behavior. Recent studies suggest that limbic territories of BG not only support reward seeking (appetitive approach) but also the encoding of aversive conditioned stimuli (CS) and the production of aversiveârelated behaviors (avoidance or escape). This study aimed to identify inside two BG nuclei, the striatum and pallidum, the territories involved in aversive behaviors and to compare the effects of stimulating these territories to those resulting from stimulation of the anterior Insula (aIns), a region that is wellâknown to be involved in aversive encoding and associated behaviors. Two monkeys performed an approach/avoidance task in which they had to choose a behavior (approach or avoidance) in an appetitive (reward) or aversive (airâpuff) context. During this task, either one (singleâcue) or two (dualâcue) CS provided essential information about which contextâadapted behavior should be selected. Microstimulation was applied during the CS presentation. Stimulation generally reduced approaches in the appetitive contexts and increased escape behaviors (premature responses) and/or passive avoidance (noninitiated action) in aversive context. These effects were more pronounced in ventral parts of all examined structures, with significant differences observed between stimulated structures. Thresholds to induce effects were lowest in the pallidum. Striatal stimulation led to the largest diversity of effects, with a subregion even leading to enhanced active avoidance. Finally, aIns stimulations produced stronger effects in the dualâcue context. These results provide causal evidence that limbic territories of BG, like aIns, play crucial roles in the selection of contextâmotivated behaviors
Detection of NTRK Fusions and TRK Expression and Performance of pan-TRK Immunohistochemistry in Routine Diagnostics:Results from a Nationwide Community-Based Cohort
Gene fusions involving NTRK1, NTRK2, and NTRK3 are rare drivers of cancer that can be targeted with histology-agnostic inhibitors. This study aimed to determine the nationwide landscape of NTRK/TRK testing in the Netherlands and the usage of pan-TRK immunohistochemistry (IHC) as a preselection tool to detect NTRK fusions. All pathology reports in 2017â2020 containing the search term âTRKâ were retrieved from the Dutch Pathology Registry (PALGA). Patient characteristics, tumor histology, NTRK/TRK testing methods, and reported results were extracted. NTRK/TRK testing was reported for 7457 tumors. Absolute testing rates increased from 815 (2017) to 3380 (2020). Tumors were tested with DNA/RNA-based molecular assay(s) (48%), IHC (47%), or in combination (5%). A total of 69 fusions involving NTRK1 (n = 22), NTRK2 (n = 6) and NTRK3 (n = 41) were identified in tumors from adult (n = 51) and pediatric (n = 18) patients. In patients tested with both IHC and a molecular assay (n = 327, of which 29 NTRK fusion-positive), pan-TRK IHC had a sensitivity of 77% (95% confidence interval (CI), 56â91) and a specificity of 84% (95% CI, 78â88%). These results showed that pan-TRK IHC has a low sensitivity in current routine practice and warrants the introduction of quality guidelines regarding the implementation and interpretation of pan-TRK IHC
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