National University of La Plata

About: National University of La Plata is a education organization based out in La Plata, Argentina. It is known for research contribution in the topics: Population & Stars. The organization has 12993 authors who have published 30013 publications receiving 495118 citations. The organization is also known as: UNLP & Universidad Nacional de La Plata.

Search for scalar leptoquarks in pp collisions at √s = 13 TeV with the ATLAS experiment

Abstract: An inclusive search for a new-physics signature of lepton-jet resonances has been performed by the ATLAS experiment. Scalar leptoquarks, pair-produced in pp collisions at √s = 13 TeV at the large hadron collider, have been considered. An integrated luminosity of 3.2 fb−1, corresponding to the full 2015 dataset was used. First (second) generation leptoquarks were sought in events with two electrons (muons) and two or more jets. The observed event yield in each channel is consistent with Standard Model background expectations. The observed (expected) lower limits on the leptoquark mass at 95% confidence level are 1100 and 1050 GeV (1160 and 1040 GeV) for first and second generation leptoquarks, respectively, assuming a branching ratio into a charged lepton and a quark of 100%. Upper limits on the aforementioned branching ratio are also given as a function of leptoquark mass. Compared with the results of earlier ATLAS searches, the sensitivity is increased for leptoquark masses above 860 GeV, and the observed exclusion limits confirm and extend the published results.

Renormalization of the inverse square potential

Abstract: The quantum-mechanical $D$-dimensional inverse square potential is analyzed using field-theoretic renormalization techniques. A solution is presented for both the bound-state and scattering sectors of the theory using cutoff and dimensional regularization. In the renormalized version of the theory, there is a strong-coupling regime where quantum-mechanical breaking of scale symmetry takes place through dimensional transmutation, with the creation of a single bound state and of an energy-dependent $s$-wave scattering matrix element.

Craniometric evidence for Palaeoamerican survival in Baja California

Abstract: A current issue on the settlement of the Americas refers to the lack of morphological affinities between early Holocene human remains (Palaeoamericans) and modern Amerindian groups, as well as the degree of contribution of the former to the gene pool of the latter1,2,3,4,5,6. A different origin for Palaeoamericans and Amerindians is invoked to explain such a phenomenon3. Under this hypothesis, the origin of Palaeoamericans must be traced back to a common ancestor for Palaeoamericans and Australians, which departed from somewhere in southern Asia and arrived in the Australian continent and the Americas around 40,000 and 12,000 years before present, respectively. Most modern Amerindians are believed to be part of a second, morphologically differentiated migration3. Here we present evidence of a modern Amerindian group from the Baja California Peninsula in Mexico, showing clearer affinities with Palaeoamerican remains than with modern Amerindians. Climatic changes during the Middle Holocene probably generated the conditions for isolation from the continent, restricting the gene flow of the original group with northern populations, which resulted in the temporal continuity of the Palaeoamerican morphological pattern to the present.

Environmental toxicology and chemistry in Latin America

Abstract: Fil: Carriquiriborde, Pedro. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Quimica. Centro de Investigaciones del Medio Ambiente; Argentina

Preservation of Microstructure in Peach and Mango during High-pressure-shift Freezing

Abstract: A histological technique was used to evaluate modifications on the microstructure of peach and mango due to classical methods of freezing and those produced by high-pressure-shift freezing (HPSF). With the high-pressure-shift method, samples are cooled under pressure (200 MPa) to -20°C without ice formation, then pres- sure is released to atmospheric pressure (0.1 MPa). The high level of supercooling (approximately 20°C) leads to uniform and rapid ice nucleation throughout the volume of the specimen. This method maintained the original tissue structure to a great extent. Since problems associated with thermal gradients are minimized, high-pressure-shift pansion when the unfrozen inner part of the product undergoes phase transition. When the stress generated in the interior of the product exceeds the resistance of the frozen material at the surface, freeze-cracking takes place. With high-pressure-shift freezing (HPSF), this problem may be avoided since the initial formation of ice is instantaneous and homogenous throughout the volume of the product, thus eliminating internal stresses. High pressures can be applied during freezing of foods in dif- ferent ways: Phase transition can occur either under constant pressure (pressure-assisted freezing to obtain ice I or other types of ice: ice II, ice III, and so on) or due to a pressure change (pressure-shift freezing) as Knorr and others (1998) pointed out. Two types of high-pressure-shift freezing can be distinguished: one in which expansion occurs gradually (always near the equi- librium curve), and the other in which expansion to atmospher- ic pressure occurs suddenly, thus achieving considerable super- cooling at atmospheric pressure. Fuchigami and others (1997a, 1997b) conducted pressure-assisted freezing experiments to ob- tain several ices different from ice I, and high-pressure-shift freezing experiments with gradual expansion (lasting 1 min from 200 MPa to atmospheric pressure) in carrots. They found that the less harmful freezing methods, for vegetable structure, were pressure-assisted freezing inducing formation of ice III, with smaller specific volume than liquid water, and gradual high-pressure shift freezing. However, these authors did not use high-pressure-shift freezing with abrupt expansions. The objective of the present work was to analyze the effect of freezing on the microstructure of 2 whole fruits of large size— peach and mango —by comparing traditional methods and high-pressure-shift freezing with abrupt expansions.