Transport coefficients for inelastic Maxwell mixtures

The Boltzmann equation for inelastic Maxwell models is used to determine the Navier-Stokes transport coefficients of a granular binary mixture in $d$ dimensions. The Chapman-Enskog method is applied to solve the Boltzmann equation for states near the (local) homogeneous cooling state. The mass, heat, and momentum fluxes are obtained to first order in the spatial gradients of the hydrodynamic fields, and the corresponding transport coefficients are identified. There are seven relevant transport coefficients: the mutual diffusion, the pressure diffusion, the thermal diffusion, the shear viscosity, the Dufour coefficient, the pressure energy coefficient, and the thermal conductivity. All these coefficients are {\em exactly} obtained in terms of the coefficients of restitution and the ratios of mass, concentration, and particle sizes. The results are compared with known transport coefficients of inelastic hard spheres obtained analytically in the leading Sonine approximation and by means of Monte Carlo simulations. The comparison shows a reasonably good agreement between both interaction models for not too strong dissipation, especially in the case of the transport coefficients associated with the mass flux.Comment: 9 figures, to be published in J. Stat. Phy

Project in Entrepreneurship Tintaya Spirit

The present project evaluates the potential of the business idea; the possibility of creating an Eco-hotel on Lobitos Beach, located in the northern coast of Peru; more precisely in the province of Talara, near to Piura city; ideal place with sandy beaches to practice water sports, mainly surfing. And where, despite the presence of some hotels, there is none that stands out for a differentiation in their accommodation and services. Also analyzes its relationship with current industry, the needs of the target market, the ability of entrepreneurs to establish and manage the business, as well as the financial needs of the project. The development of the business idea we want to combine the passion for share our best with people, nature, culture and activities related to the sea, with our knowledge and experience in the field of business administration. Our goal goes beyond creating a profitable and lasting business over time, we also want to highlight the Peruvian culture related to the region, generate a positive impact on all the stakeholders, especially on the environment and the inhabitants of the area

Aspectos que inciden en el aprendizaje de las matem?ticas de los estudiantes del grado sexto y once de la Instituci?n Educativa Doima

85 p. Recurso Electr?nicoLa investigaci?n Aspectos que inciden en el aprendizaje de las matem?ticas de los estudiantes del grado sexto y once de la instituci?n educativa Doima: percepci?n; surge de la preocupaci?n por los bajos resultados en las pruebas de desempe?o tanto internas como externas en los estudiantes del grado 6? de esta instituci?n y particularmente del ?ltimo informe del Instituto Colombiano de Educaci?n ICFES para los establecimientos educativos espec?ficamente para el ?rea de matem?ticas. En busca de soluciones a la problem?tica se ha hecho un recorrido con la intenci?n de encontrar una raz?n por la cual los estudiantes no responden a los planes de mejoramiento planteados por los docentes del ?rea y se concluye que es necesario realizar un diagn?stico para encontrar la raz?n que est? causando el bajo desempe?o en los estudiantes. Como se ha logrado percibir una baja motivaci?n generalizada en los estudiantes hacia la clase de matem?ticas; el presente trabajo busca ahondar en tres factores que inciden en el nivel de motivaci?n de los educandos como son los componentes afectivos, cognitivo y conductual para poder identificar en cu?l de ellos se logra encontrar la ra?z del conflicto. Para ello se estructura un cuestionario tomado y adaptado de Palacios, Arias, y Arias, (2014). Y complementada con el cuestionario de Motivaci?n ?rea de matem?tica de D?az, (2013), el cual se aplica no solo al grado sexto sino tambi?n a los estudiantes del grado 11 con el prop?sito de evidenciar como ha venido evolucionando la percepci?n de los estudiantes hacia la asignatura. El cuestionario se divide en los tres componentes y permite indagar por aspectos que logran dar cuenta del desinter?s de muchos de los estudiantes por la disciplina a pesar del reconocimiento de su importancia para su futuro; as? mismo se logra percibir la honestidad de los estudiantes al aceptar su culpabilidad y apat?a hacia ellas. Conocer los resultados de esta encuesta permite identificar y reconocer las percepciones de los estudiantes e identificar en donde se encuentran las mayores amenazas para poder intervenirlas a partir del uso de diversas estrategias acordes con las necesidades, las que ser?n indispensables para mejorar los desempe?os de los estudiantes de tal forma que estos se vean reflejados no solo en los resultados de las pruebas sino en la disposici?n de los estudiantes hacia la disciplina. De hecho, estos resultados permiten reconocer que el docente no puede limitarse al an?lisis de la dimensi?n cognitiva, puesto que debe abordar la problem?tica desde las percepciones de los estudiantes frente a la asignatura, para comprender los procesos y poder transformar las actitudes y prejuicios con los cuales estos se enfrentan a su proceso de aprendizaje de la matem?tica. Palabras claves: estudiantes, aprendizaje, percepci?n, motivaci?n, matem?ticasThe research Affective aspects that affect the learning of the mathematics of the sixth grade students of the Doima Educational Institution: Motivation; Arises from the concern about the low results in the tests of performance both internal and external in the students of the 6? degree. Of this institution and particularly the last report of the Colombian Institute of Education ICFES for educational establishments specifically for the area of mathematics. In search of solutions to the problem has been made a trip with the intention of finding a reason why students do not respond to improvement plans raised by teachers in the area and concludes that it is necessary to make a diagnosis to find the reason which is causing poor performance in students. As it has been perceived a generalized low motivation in the students towards the mathematics class, The present work seeks to delve into three factors that affect the level of motivation of learners such as affective, cognitive and behavioral components in order to identify in which of them the root of the conflict is found. For this purpose, a questionnaire is drawn up and adapted from and complemented by D?az, (2013), which applies not only to the sixth grade but also to the students of grade 11 with the purpose of demonstrating how has been evolving the students' perception of the subject. The questionnaire is divided into three components and allows to investigate aspects that manage to account for the lack of interest of many students in the discipline despite the recognition of their importance for their future; It is also possible to perceive the honesty of the students when accepting their guilt and apathy towards them. Knowing the results of this survey allows identifying and recognizing the perceptions of students and identifying where the greatest threats are to be able to intervene based on the use of different strategies according to the needs, which will be indispensable to improve student performance So that these are reflected not only in the results of the tests but also in the students' disposition towards the discipline. In fact, these results allow to recognize that the teacher cannot be limited to the analysis of the cognitive dimension, since it must approach the problematic from the perceptions of the students in front of the subject, to understand the processes and to be able to transform the attitudes and prejudices with the Which these are facing their process of learning mathematics. Keywords: students, learning, perception, motivation, mathematic

Pavement Thickness Evaluation by GPR Survey in Idaho

In 1995 and 1996, the Idaho Transportation Department (lTD) conducted a series of ground-penetrating radar (GPR) surveys as a nondestructive testing (NDT) method to evaluate the thickness of asphalt and Portland cement concrete (AC/PCC) pavements in Idaho. GPR surveys employed both air-coupled and combination air and ground coupled systems with their associated equipment and software. A total of 30 miles of AC/PCC pavements were evaluated by GPR surveys. The results obtained were correlated with the site-specific ground-truth data from borings. Knowledge of pavement layer thickness is needed to predict pavement performance, establish load carrying capacities and develop maintenance and rehabilitation priorities. In addition, for new construction, it is important to ensure that the thickness of materials being placed by the contractor is acceptably close to specification. Core sampling and test pits are destructive to the pavement system, expensive, time consuming and intrusive to traffic. The objective of the lTD study was to evaluate, compare and assess the ability of these two GPR systems to accurately measure the thickness of multiple pavement layers, and document the data nondestructively. This paper reviews the findings of these surveys and provides statistically based data for both AC and PCC pavements. The overall study has shown that reasonably accurate, dependable determination of pavement thickness can be achieved by using GPR survey for conditions encountered in Idaho

MRI phenotyping of underlying cerebral small vessel disease in mixed hemorrhage patients

Objective: To investigate underlying cerebral small vessel disease (CSVD) in patients with mixed cerebral hemorrhages patterns and phenotype them according to the contribution of the two most common sporadic CSVD subtypes: cerebral amyloid angiopathy (CAA) vs. hypertensive arteriopathy (HA). Methods: Brain MRIs of patients with intracerebral hemorrhages (ICHs) and/or cerebral microbleeds (CMBs) were assessed for the full spectrum of CSVD markers using validated scales: ICHs, CMBs, cortical superficial siderosis (cSS), white matter hyperintensities, MRI-visible perivascular spaces (PVS). PVS predominance pattern was grouped as centrum-semiovale (CSO)-PVS predominance, basal-ganglia (BG)-PVS predominance, CSO-PVS and BG-PVS equality. Patients with mixed cerebral hemorrhages were classified into mixed CAA-pattern or mixed HA-pattern according to the existence of cSS and/or a CSO-PVS predominance pattern and comparisons were performed. Results: We included 110 patients with CAA (strictly lobar ICHs/CMBs), 33 with HA (strictly deep ICHs/CMBs) and 97 with mixed lobar/deep ICHs/CMBs. Mixed patients were more similar to HA with respect to their MRI-CSVD markers, vascular risk profile and cerebrospinal fluid (CSF) measures. In the mixed patients, 33 (34%) had cSS, a CSO-PVS predominance pattern, or both, and were defined as mixed CAA-pattern cases. The mixed CAA-pattern patients were more alike CAA patients regarding their MRI-CSVD markers, CSF and genetic profile. Conclusion: Our findings suggest that the heterogeneous group of patients with mixed cerebral hemorrhages distribution can be further phenotyped according to the predominant underlying CSVD. cSS presence and a CSO-PVS predominance pattern could serve as strongly suggestive markers of a contribution from CAA among patients with mixed hemorrhages

Spectroscopic Analysis of Two Carbon Rich Post-AGB Stars

The chemical compositions of the C-rich pAGB stars IRAS 05113+1347 and IRAS 22272+5424 are determined from high-resolution optical spectra using standard LTE model atmosphere-based techniques. The stars are C, N, and $s$-process enriched suggesting efficient operation of the third-dredge up in the AGB star following a first dredge-up that increased the N abundance. Lithium is present with an abundance requiring Li manufacture. With this pair, abundance analyses are now available for 11 C-rich pAGBs. A common history is indicated and, in particular, the $s$-abundances, especially the relative abundances of light to heavy $s$-process elements, follow recent predictions for the third dredge-up in AGB stars.Comment: 41 pages (including 10 figs). 2001, ApJ, Accepte

Chemical Abundances from Inversions of Stellar Spectra: Analysis of Solar-Type Stars with Homogeneous and Static Model Atmospheres

Spectra of late-type stars are usually analyzed with static model atmospheres in local thermodynamic equilibrium (LTE) and a homogeneous plane-parallel or spherically symmetric geometry. The energy balance requires particular attention, as two elements which are particularly difficult to model play an important role: line blanketing and convection. Inversion techniques are able to bypass the difficulties of a detailed description of the energy balance. Assuming that the atmosphere is in hydrostatic equilibrium and LTE, it is possible to constrain its structure from spectroscopic observations. Among the most serious approximations still implicit in the method is a static and homogeneous geometry. In this paper, we take advantage of a realistic three-dimensional radiative hydrodynamical simulation of the solar surface to check the systematic errors incurred by an inversion assuming a plane-parallel horizontally-homogeneous atmosphere. The thermal structure recovered resembles the spatial and time average of the three-dimensional atmosphere. Furthermore, the abundances retrieved are typically within 10% (0.04 dex) of the abundances used to construct the simulation. The application to a fairly complete dataset from the solar spectrum provides further confidence in previous analyses of the solar composition. There is only a narrow range of one-dimensional thermal structures able to fit the absorption lines in the spectrum of the Sun. With our carefully selected dataset, random errors are about a factor of two smaller than systematic errors. A small number of strong metal lines can provide very reliable results. We foresee no major difficulty in applying the technique to other similar stars, and obtaining similar accuracies, using spectra with a resolving power about 50,000 and a signal-to-noise ratio as low as 30.Comment: 65 pages, figures included; uses aastex; to appear in The Astrophysical Journa

Chemical Composition of the Planet-Harboring Star TrES-1

We present a detailed chemical abundance analysis of the parent star of the transiting extrasolar planet TrES-1. Based on high-resolution Keck/HIRES and HET/HRS spectra, we have determined abundances relative to the Sun for 16 elements (Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, and Ba). The resulting average abundance of $$ $= -0.02\pm0.06$ is in good agreement with initial estimates of solar metallicity based on iron. We compare the elemental abundances of TrES-1 with those of the sample of stars with planets, searching for possible chemical abundance anomalies. TrES-1 appears not to be chemically peculiar in any measurable way. We investigate possible signs of selective accretion of refractory elements in TrES-1 and other stars with planets, and find no statistically significant trends of metallicity [$X$/H] with condensation temperature $T_c$. We use published abundances and kinematic information for the sample of planet-hosting stars (including TrES-1) and several statistical indicators to provide an updated classification in terms of their likelihood to belong to either the thin disk or the thick disk of the Milky Way Galaxy. TrES-1 is found to be a very likely member of the thin disk population. By comparing $\alpha$-element abundances of planet hosts and a large control sample of field stars, we also find that metal-rich ([Fe/H]$\gtrsim 0.0$) stars with planets appear to be systematically underabundant in [$\alpha$/Fe] by $\approx 0.1$ dex with respect to comparison field stars. The reason for this signature is unclear, but systematic differences in the analysis procedures adopted by different groups cannot be ruled out.Comment: 52 pages, 15 figures, 5 tables, accepted for publication in the Astronomical Journa

Search for the standard model Higgs boson decaying to a bbˉb\bar{b} pair in events with no charged leptons and large missing transverse energy using the full CDF data set

We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb$^{-1}$. We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a $b$ quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction for several mass hypotheses between 90 and $150 \mathrm{GeV}/c^2$. For a Higgs boson mass of $125 \mathrm{GeV}/c^2$, the observed (expected) limit is 6.7 (3.6) times the standard model prediction.Comment: Accepted by Phys. Rev. Let