560 research outputs found
Evaluating Extended Learning Time on Urban Student Performance
In the United States, children between the ages of five and eighteen spend up to 85 percent of their time out of school. After the school day ends, working parents of school-age children and youth need to secure adequate after-school care. During after school hours, between the hours of 3 p.m. and 7 p.m., 19 percent of violent offenses committed by juveniles occur (U.S. Department of Justice, 2010). On the National Assessment of Educational Progress (2015) the average eighth-grade minority student performs at about the level of the average fourth-grade white student. These data indicate that the best use of time after school involves closing the achievement gap and providing a haven for school-age children and youth (Durlak & Weissberg, 2007). The literature notes mixed opinions concerning the impact of extended learning time in the form of after-school programs. Interested stakeholders believe that, despite the inconsistent findings of the effect of after-school programs on academics and student behavior, after-school programs can narrow the achievement gap through academic and social support, promote physical fitness, and offer refuge for children and youth. Researchers believe that these varied results may stem from the need for improved research designs and a determination of which children benefit the most from participation in after-school programs (Riggs & Greenberg, 2004). This study addressed the need for extended learning time in the form of after-school programs in urban schools. It sought to evaluate the effect of participation in school-based after-school programs on the academic and social behaviors of elementary and middle school students in an urban school district. It used an ex-post facto research design and included after-school participation, Ohio Achievement Assessment data in reading and mathematics, suspensions, school attendance and demographics including race, gender, age, disability, and English proficiency as variables. Participants included students in grades three through eight from two schools in an urban district. The researcher analyzed data to compare participants in an after-school program to non-participants according to the variables mentioned above. The results of this study showed that after-school programs academically and socially benefit urban elementary and middle school students
A complex of seven vaccinia virus proteins conserved in all chordopoxviruses is required for the association of membranes and viroplasm to form immature virions
AbstractEarly events in vaccinia virus (VAC) morphogenesis, particularly the formation of viral membranes and their association with viroplasm, are poorly understood. Recently, we showed that repression of A30 or G7 expression results in the accumulation of normal viral membranes that form empty-looking immature virions (IV), which are separated from large masses of electron-dense viroplasm. In addition, A30 and G7 physically and functionally interact with each other and with the F10 protein kinase. To identify other proteins involved in early morphogenesis, proteins from cells that had been infected with vaccinia virus expressing an epitope-tagged copy of F10 were purified by immunoaffinity chromatography and analyzed by gel electrophoresis. In addition to F10, A30, and G7, viral proteins A15, D2, D3, and J1 were identified by mass spectrometry of tryptic peptides. Further evidence for the complex was obtained by immunopurification of proteins associated with epitope-tagged A15, D2, and D3. The previously unstudied A15, like other proteins in the complex, was expressed late in infection, associated with virus cores, and required for the stability and kinase activity of F10. Biochemical and electron microscopic analyses indicated that mutants in which A15 or D2 expression was regulated by the Escherichia coli lac operator system exhibited phenotypes characterized by the presence of large numbers of empty immature virions, similar to the results obtained with inducible A30 and G7 mutants. Empty immature virions were also seen by electron microscopy of cells infected with temperature-sensitive mutants of D2 or D3, though the numbers of membrane forms were reduced perhaps due to additional effects of high temperature
How and Why do Researchers Reference Data? A Study of Rhetorical Features and Functions of Data References in Academic Articles
Data reuse is a common practice in the social sciences. While published data
play an essential role in the production of social science research, they are
not consistently cited, which makes it difficult to assess their full scholarly
impact and give credit to the original data producers. Furthermore, it can be
challenging to understand researchers' motivations for referencing data. Like
references to academic literature, data references perform various rhetorical
functions, such as paying homage, signaling disagreement, or drawing
comparisons. This paper studies how and why researchers reference social
science data in their academic writing. We develop a typology to model
relationships between the entities that anchor data references, along with
their features (access, actions, locations, styles, types) and functions
(critique, describe, illustrate, interact, legitimize). We illustrate the use
of the typology by coding multidisciplinary research articles (n=30)
referencing social science data archived at the Inter-university Consortium for
Political and Social Research (ICPSR). We show how our typology captures
researchers' interactions with data and purposes for referencing data. Our
typology provides a systematic way to document and analyze researchers'
narratives about data use, extending our ability to give credit to data that
support research.Comment: 35 pages, 2 appendices, 1 tabl
Neutrino Dark Energy and Moduli Stabilization in a BPS Braneworld Scenario
A braneworld model for neutrino Dark Energy (DE) is presented. We consider a
five dimensional two-branes set up with a bulk scalar field motivated by
supergravity. Its low-energy effective theory is derived with a moduli space
approximation (MSA). The position of the two branes are parametrized by two
scalar degrees of freedom (moduli). After detuning the brane tensions a
classical potential for the moduli is generated. This potential is unstable for
dS branes and we suggest to consider as a stabilizing contribution the Casimir
energy of bulk fields. In particular we add a massive spinor (neutrino) field
in the bulk and then evaluate the Casimir contribution of the bulk neutrino
with the help of zeta function regularization techniques. We construct an
explicit form of the 4D neutrino mass as function of the two moduli. To recover
the correct DE scale for the moduli potential the usual cosmological constant
fine-tuning is necessary, but, once accepted, this model suggests a stronger
connection between DE and neutrino physics.Comment: 26 pages, 1 EPS figur
External scaffold of spherical immature poxvirus particles is made of protein trimers, forming a honeycomb lattice
During morphogenesis, poxviruses undergo a remarkable transition from spherical immature forms to brick-shaped infectious particles lacking helical or icosahedral symmetry. In this study, we show that the transitory honeycomb lattice coating the lipoprotein membrane of immature vaccinia virus particles is formed from trimers of a 62-kD protein encoded by the viral D13L gene. Deep-etch electron microscopy demonstrated that anti-D13 antibodies bound to the external protein coat and that lattice fragments were in affinity-purified D13 preparations. Soluble D13 appeared mostly trimeric by gel electrophoresis and ultracentrifugation, which is consistent with structural requirements for a honeycomb. In the presence or absence of other virion proteins, a mutated D13 with one amino acid substitution formed stacks of membrane-unassociated flat sheets that closely resembled the curved honeycombs of immature virions except for the absence of pentagonal facets. A homologous domain that is present in D13 and capsid proteins of certain other lipid-containing viruses support the idea that the developmental stages of poxviruses reflect their evolution from an icosahedral ancestor
Evidence for a colour dependence in the size distribution of main belt asteroids
We present the results of a project to detect small (~1 km) main-belt
asteroids with the 3.6 meter Canada-France-Hawaii Telescope (CFHT). We observed
in 2 filters (MegaPrime g' and r') in order to compare the results in each
band. Owing to the observational cadence we did not observe the same asteroids
through each filter and thus do not have true colour information. However
strong differences in the size distributions as seen in the two filters point
to a colour-dependence at these sizes, perhaps to be expected in this regime
where asteroid cohesiveness begins to be dominated by physical strength and
composition rather than by gravity. The best fit slopes of the cumulative size
distributions (CSDs) in both filters tend towards lower values for smaller
asteroids, consistent with the results of previous studies. In addition to this
trend, the size distributions seen in the two filters are distinctly different,
with steeper slopes in r' than in g'. Breaking our sample up according to
semimajor axis, the difference between the filters in the inner belt is found
to be somewhat less pronounced than in the middle and outer belt, but the CSD
of those asteroids seen in the r' filter is consistently and significantly
steeper than in g' throughout. The CSD slopes also show variations with
semimajor axis within a given filter, particularly in r'. We conclude that the
size distribution of main belt asteroids is likely to be colour dependent at
kilometer sizes and that this dependence may vary across the belt.Comment: 28 pages, 5 figures, submitted to the Astronomical Journa
Results of a Phase 2b Trial With GB001, a Prostaglandin D2 Receptor 2 Antagonist, in Moderate to Severe Eosinophilic Asthma
Asthma; Asthma worsening; Eosinophilic asthmaAsma; Empitjorament de l'asma; Asma eosinofĂlicaAsma; Empeoramiento del asma; Asma eosinofĂlicaBackground
Prostaglandin D2 receptor 2 (DP2) antagonists inhibit prostaglandin D2-induced effects, including recruitment and activation of cells driving asthma pathogenesis. However, challenges identifying target population and end points persist.
Research Question
What is the effect of the DP2 antagonist GB001 on asthma worsening in patients with moderate to severe eosinophilic asthma?
Study Design and Methods
In this phase IIb, randomized, double-blind, placebo-controlled, dose-ranging, parallel-group, multicenter study, GB001 or placebo was added to standard-of-care treatment in patients with moderate to severe asthma with a blood eosinophil count ≥ 250 cells/μL. Patients aged ≥ 18 years to < 75 years received one of four once-daily treatments (GB001 20 mg, 40 mg, or 60 mg or placebo). The primary end point was the proportion of patients who experienced asthma worsening by 24 weeks. Efficacy analyses were performed for the intention-to-treat population and safety analyses for patients who received at least one dose of study treatment.
Results
A total of 480 patients were treated. The ORs for asthma worsening for GB001 20 mg, 40 mg, and 60 mg vs placebo were 0.674 (95% CI, 0.398-1.142), 0.677 (95% CI, 0.399-1.149), and 0.651 (95% CI, 0.385-1.100), respectively. Analysis according to baseline blood eosinophil levels and/or fractional exhaled nitric oxide did not show greater treatment effects with higher values. Elevated liver aminotransferase levels and adverse events leading to discontinuation were more frequent for GB001 60 mg than with placebo, GB001 20 mg, and GB001 40 mg.
Interpretation
Although GB001 did not significantly reduce the odds of asthma worsening, reductions favoring GB001 were observed. Treatment effects were consistent regardless of high/low type 2 phenotype. The overall safety profile was acceptable, although GB001 60 mg was associated with risk of liver injury.This work was supported by GB001, Inc., a wholly owned subsidiary of Gossamer Bio, Inc
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Testicular degeneration in Bclw-deficient mice
To identify genes required for mammalian spermatogenesis, we screened lines of mutant mice created using a retroviral gene-trap system for male infertility. Homozygous ROSA41 male mice exhibit sterility associated with progressive testicular degeneration. Germ-cell defects are first observed at 19 days post-natal (p19). Spermatogenesis is blocked during late spermiogenesis in young adults. Gradual depletion of all stages of germ cells results in a Sertoli-cell-only phenotype by approximately six months of age. Subsequently, almost all Sertoli cells are lost from the seminiferous tubules and the Leydig cell population is reduced. Molecular analysis indicates that the gene mutated is Bclw, a death-protecting member of the Bcl2 family. The mutant allele of Bclw in ROSA41 does not produce a Bclw polypeptide. Expression of Bclw in the testis appears to be restricted to elongating spermatids and Sertoli cells. Potential roles for Bclw in testicular function are discussed
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