2,286 research outputs found
Addressing invisibility of Asian-American history and cultural heritage in North American school curricula : a curriculum guide
Presents a curriculum guide for upper elementary students (5th grade) including rationale and background research on need for critically informed multicultural education, an overview of the history of Chinese immigrants in the United States, origin and prevalence of Asian-American stereotypes, and underrepresentation of Asian-Americans in curriculum
The Cluster and Large Scale Environments of Quasars at z < 0.9.
We present an investigation into the environments of quasars with respect to galaxy clus-
ters, and environment evolution with redshift and luminosity. The positions of quasars
with respect to clusters have been studied using cluster and quasar catalogues available,
covering the redshift range 0.2 < z < 1.2. The 2D projected separations and the 3D
separations have been found and the orientation of the quasar with respect to the major
axis of the closest cluster calculated, introducing new information to previous work.
The positions of quasars with respect to clusters of galaxies will give an indication
of the large scale environment of quasars and potentially clues as to which formation
mechanisms are likely to dominate at various redshifts. For example, galaxy mergers
are most likely to occur in galaxy group environments and will create luminous quasars.
Galaxy harassment is more likely to occur on the outskirts of galaxy clusters and create
lower luminosity AGN. Secular processes such as bar instability can also create AGN and
are likely to be the cause of nuclear activity in isolated galaxies. The aim of this work is
to study the large scale environment over a large redshift range and study the evolution
as well as any change in environment with quasar luminosity and redshift. Another aim
of this work is to study the orientation of a quasar with respect to a galaxy cluster. If
galaxy clusters lie orientated along filaments, the position of a quasar with respect to a
cluster will give an indication as to where quasars lie with respect to the filament and
therefore the large scale structure.
There is a deficit of quasars lying close to cluster centres for 0.4 < z < 0.8, indicating
a preference for less dense environments, in agreement with previous work. Studying
the separations as a function of cluster richness, there was a change in quasars lying
closer to poorer clusters for z < 0.2 (Lietzen et al. 2009) to lying closer to richer clusters
for 0.2 < z < 0.4, though more clusters at low redshifts will be needed to confirm
this. There is no obvious relation between the orientation angle between a quasar and
the major axis of the closest galaxy cluster and 2D projected separations. Using faint
(Mr > −23.0 mag) and bright (Mr < −23.0 mag) quasars, there is no difference between
the two magnitude samples for the 2D separations or the cluster richness, in contrast
to Strand et al. (2008) who found brighter quasars lying in denser environments than
dimmer quasars. These is no change with redshift (over 0 < z < 1.2) in the positions of
the quasars with respect to the cluster or the cluster richness as a function of absolute
quasar magnitude. There is also no preferred orientation between the quasar and the
cluster major axis for bright or faint quasars.
Spectra of a selection of 680 star forming galaxies, red galaxies, and AGN were taken by
Luis Campusano and Ilona S¨ochting and 515 redshifts calculated. Though few of these
galaxies turned out to be cluster members as was originally intended, it was possible
to use these galaxies to study the environments of quasars with respect to star-forming
galaxies and galaxy clusters. The objects were classified (33 classed as AGN), and star
formation rates calculated and compared. Three AGN and 10 star forming galaxies lie
at the same redshift (z = 0.29) as three galaxy clusters. The three galaxy clusters have
the same orientation angle and may be part of a filament along with the star forming
galaxies and AGN. Further study will investigate the relation between AGN positions
and filaments of structure.
A sample of quasar spectra taken by Lutz Haberzettl using Hectospec on the MMT were
taken to increase the number of quasars used in this study. However, when studying
the spectra, a number of high redshift quasars showed evidence of ultra-strong UV Feii
emission in their spectra. The redshifts of these quasars were too high to be included
in the main body of the study. However, a significantly large number of ultra-strong
UV Feii emitting quasars have been found in the direction of three LQGs in the redshift
range 1.1 < z < 1.6, including the Clowes-Campusano Large Quasar Group (CCLQG).
Ly� fluorescence can increase the UV Feii emission. However, Ly� emission from other
quasars was found to be negligible compared to emission from the quasar’s central source.
Though there has been no previous indication that the LQG environment is unique, the
high level of iron emission may indicate a difference in environment. Plans for future
work based on these results are outlined
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Genetic diversity and evolution of hepatitis C virus
Inter- and intra-host Hey variation was investigated. First. a polymerase chain reactionrestriction fragment length polymorphism procedure was used to assign genotypes and subtypes to Hey infecting 567 individuals (comprising haemophilia patients, blood donors, intravenous drug users, attenders of antenatal and genito-urinary medicine clinics and chronic liver disease patients) from England and Wales. The majority of infections were associated with types 3a, 1 a and 1 b, and genotype distributions were generally similar in different sub-populations. Only 1 % of individuals were identified as being infected with more than one subtype. The intra-host variability of Hey in a selection of haemophilia patients, blood donors and intravenous drug users was then studied. For each individual, peR clones derived from the NS5b and 5' non-coding regions of the Hey genome were screened for sequence differences by denaturing gradient gel electrophoresis (DGGE) and nucleotide sequencing. The complexity and diversity of Hey quasi species, though differing between individuals, could not be correlated with the risk group to which the study patients belonged. Furthermore, no mixed genotype or subtype infections were identified. Thus the hypothesis that multiply exposed individuals are infected with a greater variety of HCY variants could not be substantiated. The DGGE procedure was further used to investigate the hypothesis that HCY genetic evolution occurs uniformly in patients during the acute phase of infection. Changes in diversity in the HCY hypervariable region 1 in individuals undergoing seroconversion were observed to differ between patients, thereby negating that hypothesis. Moreover, in a given individual, Hey could be subjected to either positive or negative selective pressure. Thus, factors other than the acute-phase host response determine the course of Hey genetic evolution
Transmission, Development, and Plasticity of Synapses
Chemical synapses are sites of contact and information transfer between a neuron and its partner cell. Each synapse is a specialized junction, where the presynaptic cell assembles machinery for the release of neurotransmitter, and the postsynaptic cell assembles components to receive and integrate this signal. Synapses also exhibit plasticity, during which synaptic function and/or structure are modified in response to activity. With a robust panel of genetic, imaging, and electrophysiology approaches, and strong evolutionary conservation of molecular components, Drosophila has emerged as an essential model system for investigating the mechanisms underlying synaptic assembly, function, and plasticity. We will discuss techniques for studying synapses in Drosophila, with a focus on the larval neuromuscular junction (NMJ), a well-established model glutamatergic synapse. Vesicle fusion, which underlies synaptic release of neurotransmitters, has been well characterized at this synapse. In addition, studies of synaptic assembly and organization of active zones and postsynaptic densities have revealed pathways that coordinate those events across the synaptic cleft. We will also review modes of synaptic growth and plasticity at the fly NMJ, and discuss how pre- and postsynaptic cells communicate to regulate plasticity in response to activity
Functional Characterization and Localization of the \u3ci\u3eAspergillus nidulan\u3c/i\u3e Formin SEPA
Formins are a family of multidomain scaffold proteins involved in actin-dependent morphogenetic events. In Aspergillus nidulans, the formin SEPA participates in two actin-mediated processes, septum formation and polarized growth. In this study, we use a new null mutant to demonstrate that SEPA is required for the formation of actin rings at septation sites. In addition, we find that a functional SEPA::GFP fusion protein localizes simultaneously to septation sites and hyphal tips, and that SEPA colocalizes with actin at each site. Using live imaging, we show that SEPA localization at septation sites and hyphal tips is dynamic. Notably, at septation sites, SEPA forms a ring that constricts as the septum is deposited. Moreover, we demonstrate that actin filaments are required to maintain the proper localization pattern of SEPA, and that the amino-terminal half of SEPA is sufficient for localization at septation sites and hyphal tips. In contrast, only localization at septation sites is affected by loss of the sepH gene product. We propose that specific morphological cues activate common molecular pathways to direct SEPA localization to the appropriate morphogenetic site
Functional Characterization and Localization of the \u3ci\u3eAspergillus nidulan\u3c/i\u3e Formin SEPA
Formins are a family of multidomain scaffold proteins involved in actin-dependent morphogenetic events. In Aspergillus nidulans, the formin SEPA participates in two actin-mediated processes, septum formation and polarized growth. In this study, we use a new null mutant to demonstrate that SEPA is required for the formation of actin rings at septation sites. In addition, we find that a functional SEPA::GFP fusion protein localizes simultaneously to septation sites and hyphal tips, and that SEPA colocalizes with actin at each site. Using live imaging, we show that SEPA localization at septation sites and hyphal tips is dynamic. Notably, at septation sites, SEPA forms a ring that constricts as the septum is deposited. Moreover, we demonstrate that actin filaments are required to maintain the proper localization pattern of SEPA, and that the amino-terminal half of SEPA is sufficient for localization at septation sites and hyphal tips. In contrast, only localization at septation sites is affected by loss of the sepH gene product. We propose that specific morphological cues activate common molecular pathways to direct SEPA localization to the appropriate morphogenetic site
Cdc42 and Par proteins stabilize dynamic adherens junctions in the Drosophila neuroectoderm through regulation of apical endocytosis
Cell rearrangements require dynamic changes in cell–cell contacts to maintain tissue integrity. We investigated the function of Cdc42 in maintaining adherens junctions (AJs) and apical polarity in the Drosophila melanogaster neuroectodermal epithelium. About one third of cells exit the epithelium through ingression and become neuroblasts. Cdc42-compromised embryos lost AJs in the neuroectoderm during neuroblast ingression. In contrast, when neuroblast formation was suppressed, AJs were maintained despite the loss of Cdc42 function. Loss of Cdc42 function caused an increase in the endocytotic uptake of apical proteins, including apical polarity factors such as Crumbs, which are required for AJ stability. In addition, Cdc42 has a second function in regulating endocytotic trafficking, as it is required for the progression of apical cargo from the early to the late endosome. The Par complex acts as an effector for Cdc42 in controlling the endocytosis of apical proteins. This study reveals functional interactions between apical polarity proteins and endocytosis that are critical for stabilizing dynamic basolateral AJs
Mission description and in-flight operations of ERBE instruments on ERBS and NOAA 9 spacecraft, November 1984 - January 1986
Instruments of the Earth Radiation Budget Experiment (ERBE) are operating on three different Earth orbiting spacecrafts: the Earth Radiation Budget Satellite (ERBS), NOAA-9, and NOAA-10. An overview is presented of the ERBE mission, in-orbit environments, and instrument design and operational features. An overview of science data processing and validation procedures is also presented. In-flight operations are described for the ERBE instruments aboard the ERBS and NOAA-9. Calibration and other operational procedures are described, and operational and instrument housekeeping data are presented and discussed
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Effect of a Fruit and Vegetable Prescription Program on Children's Fruit and Vegetable Consumption.
IntroductionMost children in families with low income do not meet dietary guidance on fruit and vegetable consumption. Fruit and vegetable prescription programs improve access to and affordability of health-supporting foods for adults, but their effect on dietary behavior among children is not known. The objective of this study was to describe the extent to which exposure to a fruit and vegetable prescription program was associated with changes in consumption among participants aged 2 to 18.MethodsWe used data from a modified National Cancer Institute screener to calculate fruit and vegetable intake among 883 children who were overweight or had obesity and participated in a 4- to 6-month fruit and vegetable prescription program at federally qualified health centers during 4 years (2012-2015). Secondary analyses in 2017 included paired t tests to compare change in fruit and vegetable consumption (cups/day) between first and last visits and multivariable linear regressions, including propensity dose-adjusted models, to model this change as a function of sociodemographic and program-specific covariates, such as number of clinical visits and value of prescription redemption.ResultsWe found a dose propensity-adjusted increase of 0.32 cups (95% confidence interval, 0.19-0.45 cups) for each additional visit while holding constant the predicted number of visits and site. An equal portion of the change-score increase was attributed to vegetable consumption and fruit consumption (β = 0.16 for each).ConclusionFruit and vegetable prescription programs in clinical settings may increase fruit and vegetable consumption among children in low-income households. Future research should use a comparison group and consider including qualitative analysis of site-specific barriers and facilitators to success
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