On the formation and physical properties of the Intra-Cluster Light in hierarchical galaxy formation models

We study the formation of the Intra-Cluster Light (ICL) using a semi-analytic model of galaxy formation, coupled to merger trees extracted from N-body simulations of groups and clusters. We assume that the ICL forms by (1) stellar stripping of satellite galaxies and (2) relaxation processes that take place during galaxy mergers. The fraction of ICL in groups and clusters predicted by our models ranges between 10 and 40 per cent, with a large halo-to-halo scatter and no halo mass dependence. We note, however, that our predicted ICL fractions depend on the resolution: for a set of simulations with particle mass one order of magnitude larger than that adopted in the high resolution runs used in our study, we find that the predicted ICL fractions are ~30-40 per cent larger than those found in the high resolution runs. On cluster scale, large part of the scatter is due to a range of dynamical histories, while on smaller scale it is driven by individual accretion events and stripping of very massive satellites, $M_{*} \gtrsim 10^{10.5} M_{\odot}$, that we find to be the major contributors to the ICL. The ICL in our models forms very late (below $z\sim 1$), and a fraction varying between 5 and 25 per cent of it has been accreted during the hierarchical growth of haloes. In agreement with recent observational measurements, we find the ICL to be made of stars covering a relatively large range of metallicity, with the bulk of them being sub-solar.Comment: Accepted for Publication in MNRAS, 19 pages, 13 figures, 1 tabl

Type-4 spinors: transmuting from Elko to single-helicity spinors

In this communication we briefly report an unexpected theoretical discovery which emerge from the mapping of Elko mass-dimension-one spinors into single helicity spinors. Such procedure unveils a class of spinor which is classified as type-4 spinor field within Lounesto classification. In this paper we explore the underlying physical and mathematical contents of the type-4 spinor.Comment: 9 pages, 0 figure

On the bilinear covariants associated to mass dimension one spinors

In this paper we approach the issue of Clifford algebra basis deformation, allowing for bilinear covariants associated to Elko spinors which satisfy the Fierz-Pauli-Kofink identities. We present a complete analysis of covariance, taking into account the involved dual structure associated to Elko. Moreover, the possible generalizations to the recently presented new dual structure are performed.Comment: 9 pages, 0 figure

Project-Based Learning Approach in Teaching Information and Communications Technology

The idea of outcomes-based education shifts educators from content-deliverer to project manager, facilitating the investigation of learning approaches and focusing on deeper learning to develop students’ essential skills for their career readiness. This study established the effectiveness of the project-based learning (PBL) approach in teaching topics on Information and Communications Technology (ICT) among selected students of three programs at President Ramon Magsaysay State University (PRMSU), Iba, Zambales during 2nd semester SY 2018-2019. The study employed a descriptive research method to describe and interpret the present condition and relate to the desired objectives. Descriptive and inferential statistics were used in analyzing data gathered. The study findings conclude that student-respondents had a “Fair” level of performance in ICT topics during the pre-test while “Very Good” after using the PBL approach; the PBL approach was effectively based on the result analysis of mean, frequency counts, standard deviation, and t-test computation. The variance test analysis revealed a significant improvement in students’ performance on ICT topics, as reflected in the post-test result. Recommendations are provided

Using Technology to Determine Factorability or Non-factorability of Quadratic Algebraic Trinomials

This paper is aimed for mathematics educators who teach algebra, more specifically, the factoring of quadratic algebraic expressions, and who want to enhance student learning of this topic using technology in conjunction with the Middle Term Splitting Method (Donnell, 2010; MTSM 2016a; MTSM 2016b). We will use technology-based algebra and geometry connections to help determine factorability or nonfactorability of quadratic algebraic trinomials over the integers, over the real numbers, and over the complex numbers, both with clarity, certainty and with understanding by using two equations, one derived from the coefficients of the outer terms and the other from the middle term of the quadratic algebraic trinomial. Overall, the efficiency of determining factorability or non-factorability of quadratic algebraic trinomials, using Cabri Geometry II Plus (or a graphing calculator) together with the MTSM, makes this topic comprehensible in a technology-rich environment

Evaluation of brassicas for fall forage

Various species and varieties of brassicas were evaluated for their potential to extend the grazing season and provide forage through late-fall and early winter in Colorado. The species and varieties evaluated included: rapes (Bonar, Winfred, and Barnopoli), turnips (Appin, Barkant, and Purple Top), kale (Kestral), turnip x rape hybrid (Pasja), swede (Major Plus), and radish (Groundhog). Each species/variety combination was established on two different planting dates (mid-July and mid-August) with four replicates. In order to assess the potential of the brassicas as a source of forage during the fall and early winter, the varieties were sampled at two different times (mid-October and mid-November) for their yield and nutritional value (crude protein, neutral detergent fiber, and in-vitro dry matter digestibility). The second planting date yielded less biomass compared to the first. Crude protein content of the brassicas was high for most varieties (16 to 28%); whereas the fiber content was lower compared to grasses (20 to 35%); and as a result of this, the digestibility was also high (80 to 94%). Delaying the establishment date can constrain the dry matter yield of brassicas which reduces their potential to supply forage during the fall and early winter. The information obtained from this project has enabled us to pick four brassica varieties (Barnopoli rape, Pasja hybrid, Barkant turnip, and Groundhog radish) with potential to be included in forage systems with cool-season grasses and legumes.UCR::Vicerrectoría de Docencia::Ciencias Agroalimentarias::Facultad de Ciencias Agroalimentarias::Escuela de Zootecni

Plaza Union Comunal

56 p.El presente trabajo de título tuvo como objetivo el diseño, gestión y construcción de una obra, la que por emplazarse en lo público se hace pública. La obra se proyectó a base de una necesidad latente que se descubrió una vez analizado el lugar, naciendo esta, del estudio social, espacial y económico que se hizo en la localidad. Se realizó un análisis de la situación actual y futura de lugar, con el afán de identificar y comprender las variables relevantes que influyen en el lugar físico e identificar las oportunidades existentes en éste. Paralelamente se estudian casos en que se ha logrado crear arquitectura en entornos con características similares. La obra comenzó de a poco a generar un interés por parte de los pobladores, lo que se tradujo en una fuerte intención de estos por formar parte de la obra, tanto en su planeamiento como en su construcción, lo que creo en estos una fuerte necesidad de compromiso

Latitudinal extension of low-latitude scintillations measured with a network of GPS receivers

International audienceA latitudinal-distributed network of GPS receivers has been operating within Colombia, Peru and Chile with sufficient latitudinal span to measure the absolute total electron content (TEC) at both crests of the equatorial anomaly. The network also provides the latitudinal extension of GPS scintillations and TEC depletions. The GPS-based information has been supplemented with density profiles collected with the Jicamarca digisonde and JULIA power maps to investigate the background conditions of the nighttime ionosphere that prevail during the formation and the persistence of plasma depletions. This paper presents case-study events in which the latitudinal extension of GPS scintillations, the maximum latitude of TEC depletion detections, and the altitude extension of radar plumes are correlated with the location and extension of the equatorial anomaly. Then it shows the combined statistics of GPS scintillations, TEC depletions, TEC latitudinal profiles, and bottomside density profiles collected between September 2001 and June 2002. It is demonstrated that multiple sights of TEC depletions from different stations can be used to estimate the drift of the background plasma, the tilt of the plasma plumes, and in some cases even the approximate time and location of the depletion onset. This study corroborates the fact that TEC depletions and radar plumes coincide with intense levels of GPS scintillations. Bottomside radar traces do not seem to be associated with GPS scintillations. It is demonstrated that scintillations/depletions can occur when the TEC latitude profiles are symmetric, asymmetric or highly asymmetric; this is during the absence of one crest. Comparison of the location of the northern crest of the equatorial anomaly and the maximum latitude of scintillations reveals that for 90% of the days, scintillations are confined within the boundaries of the 50% decay limit of the anomaly crests. The crests of the anomaly are the regions where the most intense GPS scintillations and the deepest TEC depletions are encountered. In accord with early results, we observe that GPS scintillations/TEC depletions mainly occur when the altitude of the magnetic equator F-region is above 500km. Nevertheless, in many instances GPS scintillations and TEC depletions are observed to exist when the F-layer is well below 500km or to persist when the F-layer undergoes its typical nighttime descent. Close inspection of the TEC profiles during scintillations/depletions events that occur when the equatorial F-layer peak is below 500km altitude reveals that on these occasions the ratio of the crest-to-equator TEC is above 2, and the crests are displaced 10° or more from the magnetic equator. When the equatorial F-layer is above 500km, neither of the two requirements is needed, as the flux tube seems to be inherently unstable. We discuss these findings in terms of the Rayleigh-Taylor instability (RTI) mechanism for flux-tube integrated quantities. We advance the idea that the seeming control that the reverse fountain effect exerts on inhibiting or suppressing GPS scintillations may be related to the redistribution of the density and plasma transport from the crests of the anomaly toward the equatorial region and then to much lower altitudes, and the simultaneous decrease of the F-region altitude. These two effects originate a decrease in the crest/trough ratio and a reduction of the crests separation, making the whole flux tube more stable to the RTI. The correspondence between crest separation, altitude of the equatorial F-region, the onset of depletions, and the altitude (latitude) extension of plumes (GPS scintillations) can be used to track the fate of the density structures