663 research outputs found
International school test scores and economic growth
We expand Hanushek and Kimko's (2000) analysis of the relationship between schooling quality, as measured by scores in international tests, and growth. We take account of another fifteen years of growth and approximately twice as many test score results. We treat the data first as a panel, relating growth only to test scores at earlier dates, and then as a cross-section. In both cases we find the effect of schooling quality on growth to be statistically significant but substantially smaller than that reported by Hanushek and Kimko (2000) and Hanushek and Woessmann (2007)
Bloodstream form trypanosoma brucei depend upon multiple metacaspases associated with RAB11-positive endosomes
Trypanosoma brucei possesses five metacaspase genes. Of these, MCA2 and MCA3 are expressed only in the mammalian bloodstream form of the parasite, whereas MCA5 is expressed also in the insect procyclic form. Triple RNAi analysis showed MCA2, MCA3 and MCA5 to be essential in the bloodstream form, with parasites accumulating pre-cytokinesis. Nevertheless, triple null mutants (Δmca2/3Δmca5) could be isolated after sequential gene deletion. Thereafter, Δmca2/3Δmca5 mutants were found to grow well both in vitro in culture and in vivo in mice. We hypothesise that metacaspases are essential for bloodstream form parasites, but they have overlapping functions and their progressive loss can be compensated for by activation of alternative biochemical pathways. Analysis of Δmca2/3Δmca5 revealed no greater or lesser susceptibility to stresses reported to initiate programmed cell death, such as treatment with prostaglandin D2. The metacaspases were found to colocalise with RAB11, a marker for recycling endosomes. However, variant surface glycoprotein (VSG) recycling processes and the degradation of internalised anti-VSG antibody were found to occur similarly in wild type, Δmca2/3Δmca5 and triple RNAi induced parasites. Thus, the data provide no support for the direct involvement of T. brucei metacaspases in programmed cell death and suggest that the proteins have a function associated with RAB11 vesicles that is independent of known recycling processes of RAB11-positive endosomes
Initial Validation of the Teacher-Created Empowering and Disempowering Motivational Climate Questionnaire in Physical Education
Purpose: Guided by Duda’s hierarchical conceptualization of the motivational climate that draws from self-determination and achievement goal theories, this study provides initial evidence of the psychometric properties of the Empowering and Disempowering Motivational Climate Questionnaire in physical education (EDMCQ-PE). Method: Questionnaire based with two samples of Welsh secondary school pupils. Results: Exploratory structural equation modeling provided a better fit of the data to the hypothesized model than confirmatory factor analysis. Moreover, a two-factor composite (i.e., empowering and disempowering) lower-order model provided an acceptable fit and clear parameter estimates. This two-factor model also demonstrated scalar gender measurement invariance. Discussion: The evidence from this study suggests the EDMCQ-PE is a promising scale for the assessment of secondary school pupils’ perceptions of the empowering and disempowering features of the motivational climate created by their physical education teachers. Conclusion: Moving forward, the statistical approach employed in this paper can inform future studies that develop questionnaire methodology in physical education and from an applied perspective; the EDMCQ-PE can be used by researchers and teachers to assess the motivational climate in PE and help inform the pedagogy underpinning teachers’ classes
Measuring the Interaction of Transcription Factor Nrf2 with Its Negative Regulator Keap1 in Single Live Cells by an Improved FRET/FLIM Analysis
Transcription
factor NF-E2 p45-related factor 2 (Nrf2) and its
principal negative regulator, Kelch-like ECH-associated protein 1
(Keap1), comprise a molecular effector and sensor system that robustly
responds to perturbations of the cellular redox homeostasis by orchestrating
a comprehensive cytoprotective program. Under homeostatic conditions,
Nrf2 is a short-lived protein, which is targeted for ubiquitination
and proteasomal degradation. Upon encounter of electrophiles, oxidants,
or pro-inflammatory stimuli, the cysteine sensors in Keap1 are chemically
modified, rendering Keap1 unable to target Nrf2 for degradation, and
consequently leading to accumulation of the transcription factor and
enhanced transcription of cytoprotective genes. A detailed understanding
of the protein–protein interactions between Nrf2 and Keap1
has been achieved by use of various in vitro systems, but few assays
are available to assess these interactions in the context of the living
cell. We previously developed an imaging-based FLIM/FRET methodology
to visualize and measure the interaction between Nrf2 and Keap1 in
single cells. Here, our goal was to improve this methodology in order
to increase throughput and precision, and decrease cell-to-cell variability.
To eliminate the possibility of orientation bias, we incorporated
a flexible linker between Keap1 and the FRET acceptor fluorescent
protein tag. To ensure the correct image capture of Nrf2 fused to
the FRET donor fluorescent protein tag, we matched the maturation
time of the fluorescent tag to the half-life of the endogenous Nrf2,
by using sfGFP as the FRET donor. Using a global binning approach
increased the assay throughput, whereas including the measured instrument
response function in the analysis improved precision. The application
of this methodology revealed a strong covariation of the results with
the expression level of the acceptor. Taking the acceptor level into
account circumvented cell-to-cell variability and enhanced sensitivity
of the measurements of the Keap1–Nrf2 interaction in live cells
RPA-Mediated Recruitment of the E3 Ligase RFWD3 Is Vital for Interstrand Crosslink Repair and Human Health
Defects in the repair of DNA inter-strand crosslinks (ICLs) are associated with the genome instability syndrome Fanconi anemia (FA). Here we report that cells with mutations in RFWD3, an E3 ubiquitin ligase that interacts with and ubiquitylates replication protein A (RPA), show profound defects in ICL repair. An amino acid substitution in the WD40 repeats of RFWD3 (I639K) found in a new FA subtype abolishes interaction of RFWD3 with RPA, thereby preventing RFWD3 recruitment to sites of ICL-induced replication fork stalling. Moreover, single point mutations in the RPA32 subunit of RPA that abolish interaction with RWFD3 also inhibit ICL repair, demonstrating that RPA-mediated RFWD3 recruitment to stalled replication forks is important for ICL repair. We also report that unloading of RPA from sites of ICL induction is perturbed in RFWD3-deficient cells. These data reveal important roles for RFWD3 localization in protecting genome stability and preserving human health
Radio source stacking and the infrared / radio correlation at microJy flux densities
We investigate the infrared / radio correlation using the technique of source
stacking, in order to probe the average properties of radio sources that are
too faint to be detected individually. We compare the two methods used in the
literature to stack sources, and demonstrate that the creation of stacked
images leads to a loss of information. We stack infrared sources in the Spitzer
extragalactic First Look Survey (xFLS) field, and the three northern Spitzer
Wide-area Infrared Extragalactic survey (SWIRE) fields, using radio surveys
created at 610 MHz and 1.4 GHz, and find a variation in the absolute strength
of the correlation between the xFLS and SWIRE regions, but no evidence for
significant evolution in the correlation over the 24-um flux density range 150
uJy - 2 mJy. We carry out the first radio source stacking experiment using
70-um-selected galaxies, and find no evidence for significant evolution over
the 70-um flux density range 10 mJy - 100 mJy.Comment: 11 pages, 12 figures. Accepted for publication in MNRA
A 610-MHz survey of the ELAIS-N1 field with the Giant Metrewave Radio Telescope - Observations, data analysis and source catalogue
Observations of the ELAIS-N1 field taken at 610 MHz with the Giant Metrewave
Radio Telescope are presented. Nineteen pointings were observed, covering a
total area of 9 square degrees with a resolution of 6" x 5", PA +45 deg. Four
of the pointings were deep observations with an rms of 40 microJy before
primary beam correction, with the remaining fifteen pointings having an rms of
70 microJy. The techniques used for data reduction and production of a
mosaicked image of the region are described, and the final mosaic is presented,
along with a catalogue of 2500 sources detected above 6 sigma. This work
complements the large amount of optical and infrared data already available on
the region. We calculate 610-MHz source counts down to 270 microJy, and find
further evidence for the turnover in differential number counts below 1 mJy,
previously seen at both 610 MHz and 1.4 GHz.Comment: 12 pages, 18 figures, two tables. Table 1 can be found in full via
http://www.mrao.cam.ac.uk/surveys/ . Accepted for publication in MNRA
Investigations on the cytology and life-cycle of the parasitic dinoflagellate Hematodinium sp associated with mortality of Nephrops norvegicus
Dinoflagellate parasites of the genus Hematodinium are associated with heavy mortality of the Norway lobster (Nephrops norvegicus) off the west coast of Scotland. The Syndinean dinoflagellate has been isolated from N. norvegicus and has been successfully cultured axenically in vitro. Twelve isolates have been serially cultivated in a medium of 10% fetal calf serum in a balanced Nephrops saline with added antibiotics at 8-10°C. In this medium the parasite undergoes developmental changes that are believed to represent stages in the life cycle of the parasite in vivo. This is the first complete life cycle in vitro to be described for a Syndinean dinoflagellate.
Flagellate dinospores arise in vitro from circulating sporogenic parasite forms - sporoblasts removed in the haemolymph from infected lobsters. Sporogenic parasites are recognised by the presence in the cytoplasm of structures not found in the trophont. These are (1) trichocysts and (2) flagellar hairs within swollen endoplasmic reticulum cisternae. Dinospores are of two types - a larger macrospore and a smaller, more active microspore. Individual isolates produce one or the other, not both. Condensation of chromosomes in the nucleus is more pronounced in the microspore than in the macrospore. Both spore types germinate after 18-62 days in the culture medium to produce the main multiplicative stage of the parasite in vitro - the multinucleate filamentous trophont. No fusion of flagellates has been observed and each type of spore can germinate independently of the presence of the other, indicating that the spores are not gametes. The filamentous trophonts correspond to the only form of the type species of the genus, Hematodinium perezi, found circulating in the blood of infected crabs by Chatton and Poisson (1931). (DXN004,487
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