922 research outputs found

    The Photoionization of a Star-Forming Core in the Trifid Nebula

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    We have carried out a comprehensive multiwavelength study of Bright-Rimmed Globule TC2 in the Trifid Nebula using the IRAM~30m telescope, the VLA centimeter array and the Infrared Space Observatory (ISO). TC2 is one of the very few globules to exhibit signs of active ongoing star formation while being photoevaporated. The study of the kinematics shows that TC2 is currently undergoing an implosion driven by the ionization field. The physical structure of the molecular core, the Photon-Dominated Region and the ionization front are characterized. The properties of the PDR are in good agreement with some recent PDR models. The molecular emission suggests that the star formation process was probably initiated a few 0.1 Myr ago, in the large burst which led to the formation of the nebula. The impact of photoionization on the star formation process appears limited.Peer reviewe

    A new approach to etching low‐carbon microalloyed steels to reveal prior austenite grain boundaries and the dual‐phase microstructure

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    A modification to picric acid solutions has been undertaken to reveal the prior-austenite grain boundaries in microalloyed steels as a result of elemental segregation. It has been found the maximum addition of sodium dodecyl sulphate plus hydrochloric acid to fully reveal both the prior austenite grain boundaries and the final post-processed structures in these steels

    Welfare of rainbow trout at slaughter: integrating behavioural, physiological, proteomic and quality indicators and testing a novel fast-chill stunning method

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    A critical point in the life of a captive fish is the final stages of production, not only in welfare terms but also due to effects on meat quality, carcass appearance and derived economic impacts. The most common method to slaughter fish is by asphyxia either in ice-water or in the open air. In humane slaughter procedures, however, a stunning method needs to be implemented to render the fish immediately unconscious (within one second) until death. The objective of this research was to evaluate and compare the effectiveness and welfare effects of four types of stunning methods in rainbow trout (O. mykiss): cold shock by fast-chilling as a novel method, where the fish were immersed in liquid water at −8 °C, asphyxia (as the currently used method), electrical stunning, and anaesthesia with MS-222. We used a total of 176 trout (mean weight 524 ± 138 g), combining behavioural (individual swimming activity, equilibrium, opercular movement and eye-roll), physiological (heart rate and electrocardiogram amplitude) and circulating (plasma cortisol and osmolality) indicators with brain proteomic signatures. We also analysed the effects on fillet shelf-life and quality in each method (rigor mortis, water content, fillet colour, pH and ATP degradation). Anaesthesia effectively induced unconsciousness, with regular and strong heartbeat and low cortisol. Quality indicators were the best among all the methods assessed. Electric shock was found to be an effective and irreversible method for inducing unconsciousness, with strong heartbeat and large variation in cortisol response and quality indicators similar to anaesthesia. On the contrary, asphyxia presented indicators of poor welfare (e.g., long-lasting consciousness throughout the slaughter process, high cortisol levels), with very low flesh quality parameters. Fast-chilling also resulted in extreme signs of stress (intense mucus release, haemorrhage and no loss of consciousness), low ATP content and the worst proteomic signatures, along with an early onset and resolution of rigor mortis (6 and 48 h, respectively). Our results reinforce the idea that electric stunning is a promising humane method to stun farmed trout. In contrast, the fast-chilling method showed very poor results both in welfare and in quality, indicating that it is not a viable humane alternative to asphyxia. Moreover, the proteome analysis provided valuable insights into the brain mechanisms of rainbow trout at slaughter, offering potential fine-scale biomarkers of welfare.Provincia Autonoma di Trento; Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/acceptedVersio

    Orbital Ordering in Paramagnetic LaMnO3 and KCuF3

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    {\it Ab-initio} studies of the stability of orbital ordering, its coupling to magnetic structure and its possible origins (electron-phonon and/or electron-electron interactions) are reported for two perovskite systems, LaMnO3_3 and KCuF3_3. We present a new Average Spin State (ASS) calculational scheme that allowed us to treat a paramagnetic state. Using this scheme, we succesfully described the experimental magnetic/orbital phase diagram of both LaMnO3_3 and KCuF3_3 in crystal structures when the Jahn-Teller distortions are neglected. Hence, we conclude that the orbital ordering in both compounds is purely electronic in origin.Comment: 10 pages, 5 figure

    Dynamical mean-field theory of spiking neuron ensembles: response to a single spike with independent noises

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    Dynamics of an ensemble of NN-unit FitzHugh-Nagumo (FN) neurons subject to white noises has been studied by using a semi-analytical dynamical mean-field (DMF) theory in which the original 2N2 N-dimensional {\it stochastic} differential equations are replaced by 8-dimensional {\it deterministic} differential equations expressed in terms of moments of local and global variables. Our DMF theory, which assumes weak noises and the Gaussian distribution of state variables, goes beyond weak couplings among constituent neurons. By using the expression for the firing probability due to an applied single spike, we have discussed effects of noises, synaptic couplings and the size of the ensemble on the spike timing precision, which is shown to be improved by increasing the size of the neuron ensemble, even when there are no couplings among neurons. When the coupling is introduced, neurons in ensembles respond to an input spike with a partial synchronization. DMF theory is extended to a large cluster which can be divided into multiple sub-clusters according to their functions. A model calculation has shown that when the noise intensity is moderate, the spike propagation with a fairly precise timing is possible among noisy sub-clusters with feed-forward couplings, as in the synfire chain. Results calculated by our DMF theory are nicely compared to those obtained by direct simulations. A comparison of DMF theory with the conventional moment method is also discussed.Comment: 29 pages, 2 figures; augmented the text and added Appendice

    Exchange coupling in CaMnO3_3 and LaMnO3_3: configuration interaction and the coupling mechanism

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    The equilibrium structure and exchange constants of CaMnO3_3 and LaMnO3_3 have been investigated using total energy unrestricted Hartree-Fock (UHF) and localised orbital configuration interaction (CI) calculations on the bulk compounds and Mn2_2O1114_{11}^{14-} and Mn2_2O1116_{11}^{16-} clusters. The predicted structure and exchange constants for CaMnO3_3 are in reasonable agreement with estimates based on its N\'eel temperature. A series of calculations on LaMnO3_3 in the cubic perovskite structure shows that a Hamiltonian with independent orbital ordering and exchange terms accounts for the total energies of cubic LaMnO3_3 with various spin and orbital orderings. Computed exchange constants depend on orbital ordering. UHF calculations tend to underestimate exchange constants in LaMnO3_3, but have the correct sign when compared with values obtained by neutron scattering; exchange constants obtained from CI calculations are in good agreement with neutron scattering data provided the Madelung potential of the cluster is appropriate. Cluster CI calculations reveal a strong dependence of exchange constants on Mn d eg_g orbital populations in both compounds. CI wave functions are analysed in order to determine which exchange processes are important in exchange coupling in CaMnO3_3 and LaMnO3_3.Comment: 25 pages and 9 postscript figure

    The Physics of turbulent and dynamically unstable Herbig-Haro jets

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    The overall properties of the Herbig-Haro objects such as centerline velocity, transversal profile of velocity, flow of mass and energy are explained adopting two models for the turbulent jet. The complex shapes of the Herbig-Haro objects, such as the arc in HH34 can be explained introducing the combination of different kinematic effects such as velocity behavior along the main direction of the jet and the velocity of the star in the interstellar medium. The behavior of the intensity or brightness of the line of emission is explored in three different cases : transversal 1D cut, longitudinal 1D cut and 2D map. An analytical explanation for the enhancement in intensity or brightness such as usually modeled by the bow shock is given by a careful analysis of the geometrical properties of the torus.Comment: 17 pages, 10 figures. Accepted for publication in Astrophysics & Spac

    Abrupt weaning type combined to stress during late pregnancy in sheep present economic losses on carcass and low testicular development in lambs

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    This study investigates the combined effect of the progressive or abrupt weaning after the stress during middle and late pregnancy on performance and development of lambs. Twenty-four male lambs were used, born from 18 Santa Ines ewes that were divided into three experimental groups. Pregnant ewes were submitted to the application of Lipolysaccharides E. coli (LPS) during the 70 th day of pregnancy (Ig; n=12) or at the 120 th day (Fg; n=8). Animals were kept as control (Cg; n=14). Lambs born in a 6 day interval were subjected to two types of weaning (Pw: progressive weaning; Aw: abrupt weaning at 45 days of age). Lamb data, including testicular development, yield carcass and economic cost were analyzed. Means were compared by F test and Student's t test (P0.05). The highest yields in gross margin was observed for the Cg group and the lowest for Fg (P0.05). On lambs’ testicular weight, Cg average value was higher than Fg (P0.05). The combined effect of LPS challenge as a simulated disease process during late pregnancy and abrupt weaning change the testicular weight and the yield carcass, resulting in economic losses

    Results of an early access treatment protocol of daratumumab monotherapy in spanish patients with relapsed or refractory multiple myeloma

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    Daratumumab is a human CD38-targeted monoclonal antibody approved as monotherapy for heavily pretreated relapsed and refractory multiple myeloma. We report findings for the Spanish cohort of an open-label treatment protocol that provided early access to daratumumab monotherapy and collected safety and patient-reported outcomes data for patients with relapsed or refractory multiple myeloma. At 15 centers across Spain, intravenous daratumumab (16mg/kg) was administered to 73 patients who had ≥3 prior lines of therapy, including a proteasome inhibitor and an immunomodulatory drug, or who were double refractory to both. The median duration of daratumumab treatment was 3.3 (range: 0.03–13.17) months, with a median number of 12 (range: 1–25) infusions. Grade 3/4 treatment-emergent adverse events were reported in 74% of patients and included lymphopenia (28.8%), thrombocytopenia (27.4%), neutropenia (21.9%), leukopenia (19.2%), and anemia (15.1%). Common (>5%) serious treatmentemergent adverse events included respiratory tract infection (9.6%), general physical health deterioration (6.8%), and back pain (5.5%). Infusion-related reactions occurred in 45% of patients. The median change from baseline in all domains of the EQ-5D-5L and EORTC QLQ-C30 was mostly 0. A total of 18 (24.7%) patients achieved a partial response or better, with 10 (13.7%) patients achieving a very good partial response or better. Median progression-free survival was 3.98 months. The results of this early access treatment protocol are consistent with previously reported trials of daratumumab monotherapy and confirm its safety and antitumoral efficacy in Spanish patients with heavily treated relapsed or refractory multiple myeloma
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