3,931 research outputs found
Mms22p protects Saccharomyces cerevisiae from DNA damage induced by topoisomerase II
The cleavage reaction of topoisomerase II, which creates double-stranded DNA breaks, plays a central role in both the cure and initiation of cancer. Therefore, it is important to understand the cellular processes that repair topoisomerase II-generated DNA damage. Using a genome-wide approach with Saccharomyces cerevisiae, we found that Δmre11, Δxrs2, Δrad50, Δrad51, Δrad52, Δrad54, Δrad55, Δrad57 and Δmms22 strains were hypersensitive to etoposide, a drug that specifically increases levels of topoisomerase II-mediated DNA breaks. These results confirm that the single-strand invasion pathway of homologous recombination is the major pathway that repairs topoisomerase II-induced DNA damage in yeast and also indicate an important role for Mms22p. Although Δmms22 strains are sensitive to several DNA-damaging agents, little is known about the function of Mms22p. Δmms22 cultures accumulate in G(2)/M, and display an abnormal cell cycle response to topoisomerase II-mediated DNA damage. MMS22 appears to function outside of the single-strand invasion pathway, but levels of etoposide-induced homologous recombination in Δmms22 cells are lower than wild-type. MMS22 is epistatic with RTT101 and RTT107, genes that encode its protein binding partners. Finally, consistent with a role in DNA processes, Mms22p localizes to discrete nuclear foci, even in the absence of etoposide or its binding partners
Development of the 'SNS Older Adults measure' (SNS-OA) to examine social network site use in older adults
Objectives: Social Networking Sites (SNSs) may ameliorate loneliness in later life but no measure of SNS use for this population exists. This study describes the development of the ‘SNS Older Adults measure’ (SNS-OA), to improve understanding of older adults’ SNS use and its relationship to social wellbeing. /
Methods: The SNS-OA underwent initial development, including literature reviews and consultation with target population (n = 9) and experts (n = 9); piloting (n = 74), and evaluation of psychometric properties (n = 263). /
Results: The final measure comprised three ‘motive’ scales (using SNSs to maintain close ties, maintain and strengthen weaker ties and diversion), and two ‘affect’ scales (positive/negative). Whilst many items were weakly endorsed by participants, the measure demonstrated good reliability (Cronbach α = 0.85; ICC = 0.82) and some convergent validity, with some subscales correlating with a personality measure in hypothesised directions. No statistically significant correlations were observed between the measure and social wellbeing. /
Conclusions: Despite the measure’s limitations, this research has enabled a better understanding of SNS use in older adults and has important implications for research in this area. Findings also suggest a complex relationship between social wellbeing and SNS use in later life
Interpreting Tuberculin Skin Tests in a Population With a High Prevalence of HIV, Tuberculosis, and Nonspecific Tuberculin Sensitivity
Understanding the epidemiology and clinical course of tuberculosis is hampered by the absence of a perfect test for latent tuberculosis infection. The tuberculin skin test (TST) is widely used but suffers poor specificity in those receiving the bacille Calmette-Guérin vaccine and poor sensitivity in individuals with human immunodeficiency virus (HIV) infections. TST responses for a target population in Harare, Zimbabwe (HIV prevalence, 21%), recruited in 2005–2006, were interpreted by using a separate calibration population in Harare, for which interferon-gamma release assays (enzyme-linked immunosorbent spot (ELISpot)) results were also known. Statistical fitting of the responses in the calibration population allowed computation of the probability that an individual in the target population with a given TST and HIV result would have tested ELISpot positive. From this, estimates of the prevalence of tuberculosis infection, and optimal TST cutpoints to minimize misdiagnosis, were computed for different assumptions about ELISpot performance. Different assumptions about the sensitivity and specificity of ELISpot gave a 40%–57% prevalence of tuberculosis infection in the target population (including HIV-infected individuals) and optimal TST cutpoints typically in the 10 mm–20 mm range. However, the optimal cutpoint for HIV-infected individuals was consistently 0 mm. This calibration method may provide a valuable tool for interpreting TST results in other populations
Foreign Aid
The goal of this presentation is to demonstrate the research regarding foreign aid. We will present how foreign aid is received in the nations of Russia, Afghanistan, and Haiti to incorporate three different regions of the world. First, we will define foreign aid by reviewing its history in comparison to how it is practiced today. We will also look at why the United States initially decided to provide foreign aid to the referenced countries, but how the original intent actually caused issues and concerns within these countries and provided little to no actual help. In addition, we will expose the problem of dependency the discussed countries have on the United States due to the current process of foreign aid. Lastly, we will present four questions to ask when researching the best methods of cross-cultural aid and a suggested call to action. By reviewing the different aspects of foreign aid, we hope to educate our audience on ways it can either weaken or empower receiving countries
Ultraviolet and Multiwavelength Variability of the Blazar 3C 279: Evidence for Thermal Emission
The gamma-ray blazar 3C 279 was monitored on a nearly daily basis with IUE,
ROSAT and EGRET for three weeks between December 1992 and January 1993. During
this period, the blazar was at a historical minimum at all wavelengths. Here we
present the UV data obtained during the above multiwavelength campaign. A
maximum UV variation of ~50% is detected, while during the same period the
X-ray flux varied by no more than 13%. At the lowest UV flux level the average
spectrum in the 1230-2700 A interval is unusually flat for this object
(~1). The flattening could represent the lowest energy tail of the
inverse Compton component responsible for the X-ray emission, or could be due
to the presence of a thermal component at ~20000 K possibly associated with an
accretion disk. The presence of an accretion disk in this blazar object, likely
observable only in very low states and otherwise hidden by the beamed, variable
synchrotron component, would be consistent with the scenario in which the seed
photons for the inverse Compton mechanism producing the gamma-rays are external
to the relativistic jet. We further discuss the long term correlation of the UV
flux with the X-ray and gamma-ray fluxes obtained at various epochs. All UV
archival data are included in the analysis. Both the X- and gamma-ray fluxes
are generally well correlated with the UV flux, approximately with square root
and quadratic dependences, respectively.Comment: 22 pages, Latex, 7 PostScript figures, to appear in The Astrophysical
Journa
NICMOS images of JVAS/CLASS gravitational lens systems
We present Hubble Space Telescope (HST) infrared images of four gravitational
lens systems from the JVAS/CLASS gravitational lens survey and compare the new
infrared HST pictures with previously published WFPC2 HST optical images and
radio maps. Apart from the wealth of information that we get from the flux
ratios and accurate positions and separations of the components of the lens
systems that we can use as inputs for better constraints on the lens models we
are able to discriminate between reddening and optical/radio microlensing as
the possible cause of differences observed in the flux ratios of the components
across the three wavelength bands. Substantial reddening has been known to be
present in the lens system B1600+434 and has been further confirmed by the
present infrared data. In the two systems B0712+472 and B1030+074 microlensing
has been pinpointed down as the main cause of the flux ratio discrepancy both
in the optical/infrared and in the radio, the radio possibly caused by the
substructure revealed in the lensing galaxies. In B0218+357 however the results
are still not conclusive. If we are actually seeing the two "true" components
of the lens system then the flux ratio differences are attributed to a
combination of microlensing and reddening or alternatively due to some
variability in at least one of the images. Otherwise the second "true"
component of B0218+357 maybe completely absorbed by a molecular cloud and the
anomalous flux density ratios and large difference in separation between the
optical/infrared and radio that we see can be explained by emission from either
a foreground object or from part of the lensing galaxy.Comment: 10 pages, 4 figures (original higher resolution figures can be
obtained at the e-mail above), to appear in MNRAS (accepted
COLA II - Radio and Spectroscopic Diagnostics of Nuclear Activity in Galaxies
We present optical spectroscopic observations of 93 galaxies taken from the
infra-red selected COLA (Compact Objects in Low Power AGN) sample. The sample
spans the range of far-IR luminosities from normal galaxies to LIRGs. Of the
galaxies observed, 78 (84%) exhibit emission lines. Using a theoretically-based
optical emission-line scheme we classify 15% of the emission-line galaxies as
Seyferts, 77% as starbursts, and the rest are either borderline AGN/starburst
or show ambiguous characteristics. We find little evidence for an increase in
the fraction of AGN in the sample as a function of far-IR luminosity but our
sample covers only a small range in infrared luminosity and thus a weak trend
may be masked. As a whole the Seyfert galaxies exhibit a small, but
significant, radio excess on the radio-FIR correlation compared to the galaxies
classified as starbursts. Compact (<0.05'') radio cores are detected in 55% of
the Seyfert galaxies, and these galaxies exhibit a significantly larger radio
excess than the Seyfert galaxies in which cores were not detected. Our results
indicate that there may be two distinct populations of Seyferts,
``radio-excess'' Seyferts, which exhibit extended radio structures and compact
radio cores, and ``radio-quiet'' Seyferts, in which the majority of the radio
emission can be attributed to star-formation in the host galaxy. No significant
difference is seen between the IR and optical spectroscopic properties of
Seyferts with and without radio cores. (Abridged)Comment: 24 pages, 4 figures, 6 tables. Accepted for publication in ApJ,
February 200
Labour supply and skills demands in fashion retailing
If, as Adam Smith once famously suggested, Britain was a nation of shopkeepers then it is now a nation of shopworkers. Retail is now a significant part of the UK economy, accounting for £256 billion in sales and one-third of all consumer spending (Skillsmart, 2007). It is the largest private sector employer in the UK, employing 3m workers, or 1 in 10 of the working population. For future job creation in the UK economy retail is also similarly prominent and the sector is expected to create a further 250,000 jobs to 2014 (Skillsmart, 2007). The centrality of retail to economic success and job creation is apparent in other advanced economies. For example, within the US, retail sales is the occupation with the largest projected job growth in the period 2004-2014 (Gatta et al., 2009) and in Australia retail accounts for 1 in 6 workers (Buchanan et al., 2003). Within the UK these workers are employed in approximately 290,000 businesses, encompassing large and small organizations and also a number of sub-sectors. This variance suggests that retail should not be regarded as homogenous in its labour demands. Hart et al. (2007) note how skill requirements and the types of workers employed may differ across the sector. This chapter further opens up this point, providing an analysis of the labour supply and skills demands for the sub-sectors of clothing, footwear and leather goods, which are described by Skillsmart (2007: 48) as being 'significant categories in UK retailing'
- …