1,058 research outputs found
Electroweak Constraints on Warped Geometry in Five Dimensions and Beyond
Here we consider the tree level corrections to electroweak (EW) observables
from standard model (SM) particles propagating in generic warped extra
dimensions. The scale of these corrections is found to be dominated by three
parameters, the Kaluza-Klein (KK) mass scale, the relative coupling of the KK
gauge fields to the Higgs and the relative coupling of the KK gauge fields to
fermion zero modes. It is found that 5D spaces that resolve the hierarchy
problem through warping typically have large gauge-Higgs coupling. It is also
found in where the additional dimensions are warped the relative
gauge-Higgs coupling scales as a function of the warp factor. If the warp
factor of the additional spaces is contracting towards the IR brane, both the
relative gauge-Higgs coupling and resulting EW corrections will be large.
Conversely EW constraints could be reduced by finding a space where the
additional dimension's warp factor is increasing towards the IR brane. We
demonstrate that the Klebanov Strassler solution belongs to the former of these
possibilities.Comment: 18 pages, 3 figures (references added) version to appear in JHE
Detection of viable Mycobacterium ulcerans in clinical samples by a novel combined 16S rRNA reverse transcriptase/IS2404 real-time qPCR assay.
Detection of Viable <em>Mycobacterium ulcerans</em> in Clinical Samples by a Novel Combined 16S rRNA Reverse Transcriptase/IS<em>2404</em> Real-Time qPCR Assa
Radiation-induced root surface caries restored with glass-ionomer cement placed in conventional and ART cavity preparations: Results at two years
The document attached has been archived with permission from the Australian Dental Association (8th Jan 2008). An external link to the publisher’s copy is included.Background: There are no published studies comparing the clinical performances of more-viscous glass-ionomer cement (GIC) restorations when placed using conventional and atraumatic restorative treatment (ART) cavity preparation methods to restore root surface caries. Methods: One dentist used encapsulated Fuji IX GP and Ketac-Molar to restore 72 conventional and 74 ART cavity preparations for 15 patients who had received cervicofacial radiation therapy. Two assessors evaluated the restorations at six, 12, and 24 months for retention, marginal defects and surface wear, and recurrent caries. Results: After two years, the cumulative restoration successes were 65.2 per cent for the conventional and 66.2 per cent for the ART cavity preparations, without statistical or clinical significance (P>0.50). Restoration dislodgement accounted for 82.8 per cent and marginal defects for 17.2 per cent of all failures. There were no instances of unsatisfactory restoration wear or recurrent caries observed. Teeth with three or more restored cervical surfaces accounted for 79.3 per cent of all failures (P<0.0001). Conclusions: For root surface caries restored with GIC, the use of hand instruments only with the ART method was an equally effective alternative to conventional rotary instrumentation for cavity preparation. Larger restorations had higher failures, usually from dislodgement.JY Hu, XC Chen, YQ Li, RJ Smales and KH Yi
Reducing Constraints in a Higher Dimensional Extension of the Randall and Sundrum Model
In order to investigate the phenomenological implications of warped spaces in
more than five dimensions, we consider a dimensional extension to
the Randall and Sundrum model in which the space is warped with respect to a
single direction by the presence of an anisotropic bulk cosmological constant.
The Einstein equations are solved, giving rise to a range of possible spaces in
which the additional spaces are warped. Here we consider models in
which the gauge fields are free to propagate into such spaces. After carrying
out the Kaluza Klein (KK) decomposition of such fields it is found that the KK
mass spectrum changes significantly depending on how the additional
dimensions are warped. We proceed to compute the lower bound on the KK mass
scale from electroweak observables for models with a bulk
gauge symmetry and models with a bulk gauge
symmetry. It is found that in both cases the most favourable bounds are
approximately TeV, corresponding to a mass of the first gauge
boson excitation of about 4-6 TeV. Hence additional warped dimensions offer a
new way of reducing the constraints on the KK scale.Comment: 27 pages, 15 figures, v3: Additional comments in sections 1, 2 and 4.
New appendix added. Five additional figures. References adde
Influenza pandemic and professional duty: family or patients first? A survey of hospital employees
BACKGROUND: Conflicts between professional duties and fear of influenza transmission to family members may arise among health care professionals (HCP). METHODS: We surveyed employees at our university hospital regarding ethical issues arising during the management of an influenza pandemic. RESULTS: Of 644 respondents, 182 (28%) agreed that it would be professionally acceptable for HCP to abandon their workplace during a pandemic in order to protect themselves and their families, 337 (52%) disagreed with this statement and 125 (19%) had no opinion, with a higher rate of disagreement among physicians (65%) and nurses (54%) compared with administrators (32%). Of all respondents, 375 (58%) did not believe that the decision to report to work during a pandemic should be left to the individual HCP and 496 (77%) disagreed with the statement that HCP should be permanently dismissed for not reporting to work during a pandemic. Only 136 (21%) respondents agreed that HCW without children should primarily care for the influenza patients. CONCLUSION: Our results suggest that a modest majority of HCP, but only a minority of hospital administrators, recognises the obligation to treat patients despite the potential risks. Professional ethical guidelines allowing for balancing the needs of society with personal risks are needed to help HCP fulfil their duties in the case of a pandemic influenza
Neutrino Mass and from a Mini-Seesaw
The recently proposed "mini-seesaw mechanism" combines naturally suppressed
Dirac and Majorana masses to achieve light Standard Model neutrinos via a
low-scale seesaw. A key feature of this approach is the presence of multiple
light (order GeV) sterile-neutrinos that mix with the Standard Model. In this
work we study the bounds on these light sterile-neutrinos from processes like
\mu ---> e + \gamma, invisible Z-decays, and neutrinoless double beta-decay. We
show that viable parameter space exists and that, interestingly, key
observables can lie just below current experimental sensitivities. In
particular, a motivated region of parameter space predicts a value of BR(\mu
---> e + \gamma) within the range to be probed by MEG.Comment: 1+26 pages, 7 figures. v2 JHEP version (typo's fixed, minor change to
presentation, results unchanged
Target profiling of an antimetastatic RAPTA agent by chemical proteomics: relevance to the mode of action.
The clinical development of anticancer metallodrugs is often hindered by the elusive nature of their molecular targets. To identify the molecular targets of an antimetastatic ruthenium organometallic complex based on 1,3,5-triaza-7-phosphaadamantane (RAPTA), we employed a chemical proteomic approach. The approach combines the design of an affinity probe featuring the pharmacophore with mass-spectrometry-based analysis of interacting proteins found in cancer cell lysates. The comparison of data sets obtained for cell lysates from cancer cells before and after treatment with a competitive binder suggests that RAPTA interacts with a number of cancer-related proteins, which may be responsible for the antiangiogenic and antimetastatic activity of RAPTA complexes. Notably, the proteins identified include the cytokines midkine, pleiotrophin and fibroblast growth factor-binding protein 3. We also detected guanine nucleotide-binding protein-like 3 and FAM32A, which is in line with the hypothesis that the antiproliferative activity of RAPTA compounds is due to induction of a G2/M arrest and histone proteins identified earlier as potential targets
Formation of Complex and Unstable Chromosomal Translocations in Yeast
Genome instability, associated with chromosome breakage syndromes and most human
cancers, is still poorly understood. In the yeast Saccharomyces
cerevisiae, numerous genes with roles in the preservation of genome
integrity have been identified. DNA-damage-checkpoint-deficient yeast cells that
lack Sgs1, a RecQ-like DNA helicase related to the human
Bloom's-syndrome-associated helicase BLM, show an increased rate of
genome instability, and we have previously shown that they accumulate recurring
chromosomal translocations between three similar genes, CAN1,
LYP1 and ALP1. Here, the chromosomal
location, copy number and sequence similarity of the translocation targets
ALP1 and LYP1 were altered to gain insight
into the formation of complex translocations. Among 844 clones with chromosomal
rearrangements, 93 with various types of simple and complex translocations
involving CAN1, LYP1 and ALP1
were identified. Breakpoint sequencing and mapping showed that the formation of
complex translocation types is strictly dependent on the location of the
initiating DNA break and revealed that complex translocations arise via a
combination of interchromosomal translocation and template-switching, as well as
from unstable dicentric intermediates. Template-switching occurred between
sequences on the same chromosome, but was inhibited if the genes were
transferred to different chromosomes. Unstable dicentric translocations
continuously gave rise to clones with multiple translocations in various
combinations, reminiscent of intratumor heterogeneity in human cancers. Base
substitutions and evidence of DNA slippage near rearrangement breakpoints
revealed that translocation formation can be accompanied by point mutations, and
their presence in different translocation types within the same clone provides
evidence that some of the different translocation types are derived from each
other rather than being formed de novo. These findings provide
insight into eukaryotic genome instability, especially the formation of
translocations and the sources of intraclonal heterogeneity, both of which are
often associated with human cancers
Racial differences in influenza vaccination among older americans 1996–2000: longitudinal analysis of the Health and Retirement Study (HRS) and the Asset and Health Dynamics Among the Oldest Old (AHEAD) survey
BACKGROUND: Influenza is a common and serious public health problem among the elderly. The influenza vaccine is safe and effective. METHODS: The purpose of the study was to determine whether frequencies of receipt vary by race, age group, gender, and time (progress from 1995/1996 to 2000), and whether any racial differences remain in age groups covered by Medicare. Subjects were selected from the Health and Retirement Study (HRS) (12,652 Americans 50–61 years of age (1992–2000)) and the Asset and Health Dynamics Among the Oldest Old (AHEAD) survey (8,124 community-dwelling seniors aged 70+ years (1993–2000)). Using multivariate logistic regression, adjusting for potential confounders, we estimated the relationship between race, age group, gender, time and the main outcome measure, receipt of influenza vaccination in the last 2 years. RESULTS: There has been a clear increase in the unadjusted rates of receipt of influenza vaccination for all groups from 1995/1996 to 2000. However, the proportions immunized are 10–20% higher among White than among Black elderly, with no obvious narrowing of the racial gap from 1995/1996 to 2000. There is an increase in rates from age 50 to age 65. After age 70, the rate appears to plateau. In multivariate analyses, the racial difference remains after adjusting for a series of socioeconomic, health, and health care related variables. (HRS: OR = 0.63 (0.55–0.72), AHEAD: OR = 0.55 (0.44–0.66)) CONCLUSIONS: There is much work left if the Healthy People 2010 goal of 90% of the elderly immunized against influenza annually is to be achieved. Close coordination between public health programs and clinical prevention efforts in primary care is necessary, but to be truly effective, these services must be culturally appropriate
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