244 research outputs found
Quebradores, dobradores e obedientes: Explorando a mediação de edTPA dos formadores de professores
This article reflects a qualitative exploratory inquiry into the lived experiences of faculty members working within a system of urban schools of education as they supported diverse teacher candidates in completing the Educative Teacher Performance Assessment (edTPA) during its first semesters of high-stakes implementation. Drawing upon questionnaire responses and semi-structured interviews, our findings demonstrate the disparity and variation in the level and kind of support offered to teacher candidates. We discuss the ways that the policy, stance, and the ethical, pedagogical, and logistical dilemmas teacher educators faced as they supported candidates intersected to shape the supports provided. Implications focus on utilization of such test scores for evaluating teacher preparation institutions, faculty relations, and the diversification of the teacher workforce. Este artículo refleja una investigación exploratoria cualitativa sobre las experiencias de vida de formadores de docentes trabajando en escuelas urbanas mientras apoyaban a candidatos a maestros para completar el programa de Evaluación del Desempeño Educativo (edTPA) durante los primeros semestres de implementación de esta propuesta de consecuencias severas. Nuestros resultados basados en respuestas al cuestionario y entrevistas semiestructuradas, muestran la disparidad y la variación en el nivel y el tipo de apoyo ofrecido a los futuros docentes. Se analizan las formas en que los posicionamientos políticos, éticos, pedagógicos y dilemas logísticos que enfrentaban los formadores de docentes influenciaban como apoyaban a los futuros docentes. Las conclusiones se centran en la utilización de resultados de este tipo de pruebas para la preparación docentes, la evaluación de las instituciones, las relaciones con los formadores docentes y la diversidad entre los docentes. Este artigo presenta uma pesquisa exploratória qualitativa sobre as experiências de vida dos formadores de professores que trabalham em escolas urbanas, apoiando futuros docentes no processo de completar a avaliação do programa do Rendimento Escolar (edTPA) durante o primeiro semestre de aplicação da presente proposta com consequências severas. Nossos resultados com base nas respostas ao questionário e entrevistas semiestruturadas mostram a disparidade e variação do nível e tipo de suporte oferecido aos futuros professores. as maneiras pelas quais os formadores docentes enfrentavam os dilemas políticos, éticos, educacionais e logísticos influenciava os apoios oferecidos aos futuros professores. Os resultados focam na utilização dos resultados de tais testes para preparação de professores, avaliação das instituições, as relações com formadores de professores e diversidade entre os professores
Simultaneous Border-Collision and Period-Doubling Bifurcations
We unfold the codimension-two simultaneous occurrence of a border-collision
bifurcation and a period-doubling bifurcation for a general piecewise-smooth,
continuous map. We find that, with sufficient non-degeneracy conditions, a
locus of period-doubling bifurcations emanates non-tangentially from a locus of
border-collision bifurcations. The corresponding period-doubled solution
undergoes a border-collision bifurcation along a curve emanating from the
codimension-two point and tangent to the period-doubling locus here. In the
case that the map is one-dimensional local dynamics are completely classified;
in particular, we give conditions that ensure chaos.Comment: 22 pages; 5 figure
Computation of Invariants of Lie Algebras by Means of Moving Frames
A new purely algebraic algorithm is presented for computation of invariants
(generalized Casimir operators) of Lie algebras. It uses the Cartan's method of
moving frames and the knowledge of the group of inner automorphisms of each Lie
algebra. The algorithm is applied, in particular, to computation of invariants
of real low-dimensional Lie algebras. A number of examples are calculated to
illustrate its effectiveness and to make a comparison with the same cases in
the literature. Bases of invariants of the real solvable Lie algebras up to
dimension five, the real six-dimensional nilpotent Lie algebras and the real
six-dimensional solvable Lie algebras with four-dimensional nilradicals are
newly calculated and listed in tables.Comment: 17 pages, extended versio
The X-ray luminous cluster underlying the bright radio-quiet quasar H1821+643
We present a Chandra observation of the only low redshift, z=0.299, galaxy
cluster to contain a highly luminous radio-quiet quasar, H1821+643. By
simulating the quasar PSF, we subtract the quasar contribution from the cluster
core and determine the physical properties of the cluster gas down to 3 arcsec
(15 kpc) from the point source. The temperature of the cluster gas decreases
from 9.0\pm0.5 keV down to 1.3\pm0.2 keV in the centre, with a short central
radiative cooling time of 1.0\pm0.1 Gyr, typical of a strong cool-core cluster.
The X-ray morphology in the central 100 kpc shows extended spurs of emission
from the core, a small radio cavity and a weak shock or cold front forming a
semi-circular edge at 15 arcsec radius. The quasar bolometric luminosity was
estimated to be 2 x 10^{47} erg per sec, requiring a mass accretion rate of 40
Msolar per yr, which corresponds to half the Eddington accretion rate. We
explore possible accretion mechanisms for this object and determine that Bondi
accretion, when boosted by Compton cooling of the accretion material, could
provide a significant source of the fuel for this outburst. We consider
H1821+643 in the context of a unified AGN accretion model and, by comparing
H1821+643 with a sample of galaxy clusters, we show that the quasar has not
significantly affected the large-scale cluster gas properties.Comment: 20 pages, 19 figures, accepted by MNRA
Mitochondrial echoes of first settlement and genetic continuity in El Salvador
Background: From Paleo-Indian times to recent historical episodes, the Mesoamerican isthmus played an important role in the distribution and patterns of variability all around the double American continent. However, the amount of genetic information currently available on Central American continental populations is very scarce. In order to shed light on the role of Mesoamerica in the peopling of the New World, the present study focuses on the analysis of the mtDNA variation in a population sample from El Salvador.
Methodology/Principal Findings: We have carried out DNA sequencing of the entire control region of the mitochondrial DNA (mtDNA) genome in 90 individuals from El Salvador. We have also compiled more than 3,985 control region profiles from the public domain and the literature in order to carry out inter-population comparisons. The results reveal a predominant Native American component in this region: by far, the most prevalent mtDNA haplogroup in this country (at ~90%) is A2, in contrast with other North, Meso- and South American populations. Haplogroup A2 shows a star-like phylogeny and is very diverse with a substantial proportion of mtDNAs (45%; sequence range 16090–16365) still unobserved in other American populations. Two different Bayesian approaches used to estimate admixture proportions in El Salvador shows that the majority of the mtDNAs observed come from North America. A preliminary founder analysis indicates that the settlement of El Salvador occurred about 13,400±5,200 Y.B.P.. The founder age of A2 in El Salvador is close to the overall age of A2 in America, which suggests that the colonization of this region occurred within a few thousand years of the initial expansion into the Americas.
Conclusions/Significance: As a whole, the results are compatible with the hypothesis that today's A2 variability in El Salvador represents to a large extent the indigenous component of the region. Concordant with this hypothesis is also the observation of a very limited contribution from European and African women (~5%). This implies that the Atlantic slave trade had a very small demographic impact in El Salvador in contrast to its transformation of the gene pool in neighbouring populations from the Caribbean facade
SASOCP position statement on the pharmacist’s role in antibiotic stewardship 2018
Antibiotics are the most commonly prescribed medicines in global healthcare practice today. Their effectiveness is crucial and often life-saving in humanity’s battle against pathogens and infectious diseases. Antibiotic/antimicrobial stewardship strategies and programmes have become vital to the preservation of effective antibiotics and the optimisation of their use. The South African Society of Clinical Pharmacy (SASOCP) has written this guideline to outline the importance, role and purpose of pharmacists in such stewardship programmes, both in the public, as well as the private hospital sectors in South Africa. It also provides an overview of various approaches to antibiotic preservation, behavioural change, stewardship measures, and monitoring strategies
A Subset of Replication Proteins Enhances Origin Recognition and Lytic Replication by the Epstein-Barr Virus ZEBRA Protein
ZEBRA is a site-specific DNA binding protein that functions as a transcriptional activator and as an origin binding protein. Both activities require that ZEBRA recognizes DNA motifs that are scattered along the viral genome. The mechanism by which ZEBRA discriminates between the origin of lytic replication and promoters of EBV early genes is not well understood. We explored the hypothesis that activation of replication requires stronger association between ZEBRA and DNA than does transcription. A ZEBRA mutant, Z(S173A), at a phosphorylation site and three point mutants in the DNA recognition domain of ZEBRA, namely Z(Y180E), Z(R187K) and Z(K188A), were similarly deficient at activating lytic DNA replication and expression of late gene expression but were competent to activate transcription of viral early lytic genes. These mutants all exhibited reduced capacity to interact with DNA as assessed by EMSA, ChIP and an in vivo biotinylated DNA pull-down assay. Over-expression of three virally encoded replication proteins, namely the primase (BSLF1), the single-stranded DNA-binding protein (BALF2) and the DNA polymerase processivity factor (BMRF1), partially rescued the replication defect in these mutants and enhanced ZEBRA's interaction with oriLyt. The findings demonstrate a functional role of replication proteins in stabilizing the association of ZEBRA with viral DNA. Enhanced binding of ZEBRA to oriLyt is crucial for lytic viral DNA replication
Text Mining for Literature Review and Knowledge Discovery in Cancer Risk Assessment and Research
Research in biomedical text mining is starting to produce technology which can make information in biomedical literature more accessible for bio-scientists. One of the current challenges is to integrate and refine this technology to support real-life scientific tasks in biomedicine, and to evaluate its usefulness in the context of such tasks. We describe CRAB – a fully integrated text mining tool designed to support chemical health risk assessment. This task is complex and time-consuming, requiring a thorough review of existing scientific data on a particular chemical. Covering human, animal, cellular and other mechanistic data from various fields of biomedicine, this is highly varied and therefore difficult to harvest from literature databases via manual means. Our tool automates the process by extracting relevant scientific data in published literature and classifying it according to multiple qualitative dimensions. Developed in close collaboration with risk assessors, the tool allows navigating the classified dataset in various ways and sharing the data with other users. We present a direct and user-based evaluation which shows that the technology integrated in the tool is highly accurate, and report a number of case studies which demonstrate how the tool can be used to support scientific discovery in cancer risk assessment and research. Our work demonstrates the usefulness of a text mining pipeline in facilitating complex research tasks in biomedicine. We discuss further development and application of our technology to other types of chemical risk assessment in the future
Neonate Human Remains: A Window of Opportunity to the Molecular Study of Ancient Syphilis
Ancient DNA (aDNA) analysis can be a useful tool in bacterial disease diagnosis in human remains. However, while the recovery of Mycobacterium spp. has been widely successful, several authors report unsuccessful results regarding ancient treponemal DNA, casting doubts on the usefulness of this technique for the diagnosis of ancient syphilis. Here, we present results from an analysis of four newborn specimens recovered from the crypt of “La Ermita de la Soledad” (XVI–XVII centuries), located in the province of Huelva in the southwest of Spain. We extracted and analyzed aDNA in three independent laboratories, following specific procedures generally practiced in the aDNA field, including cloning of the amplified DNA fragments and sequencing of several clones. This is the most ancient case, reported to date, from which detection of DNA from T. pallidum subspecies pallidum has been successful in more than one individual, and we put forward a hypothesis to explain this result, taking into account the course of the disease in neonate individuals
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