950 research outputs found

    A Terminal Velocity on the Landscape: Particle Production near Extra Species Loci in Higher Dimensions

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    We investigate particle production near extra species loci (ESL) in a higher dimensional field space and derive a speed limit in moduli space at weak coupling. This terminal velocity is set by the characteristic ESL-separation and the coupling of the extra degrees of freedom to the moduli, but it is independent of the moduli's potential if the dimensionality of the field space is considerably larger than the dimensionality of the loci, D >> d. Once the terminal velocity is approached, particles are produced at a plethora of nearby ESLs, preventing a further increase in speed via their backreaction. It is possible to drive inflation at the terminal velocity, providing a generalization of trapped inflation with attractive features: we find that more than sixty e-folds of inflation for sub-Planckian excursions in field space are possible if ESLs are ubiquitous, without fine tuning of initial conditions and less tuned potentials. We construct a simple, observationally viable model with a slightly red scalar power-spectrum and suppressed gravitational waves; we comment on the presence of additional observational signatures originating from IR-cascading and individual massive particles. We also show that moduli-trapping at an ESL is suppressed for D >> d, hindering dynamical selection of high-symmetry vacua on the landscape based on this mechanism.Comment: 46 pages, 6 figures. V3: typos corrected compared to JHEP version, conclusions unchange

    Multiple ATR-Chk1 Pathway Proteins Preferentially Associate with Checkpoint-Inducing DNA Substrates

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    The ATR-Chk1 DNA damage checkpoint pathway is a critical regulator of the cellular response to DNA damage and replication stress in human cells. The variety of environmental, chemotherapeutic, and carcinogenic agents that activate this signal transduction pathway do so primarily through the formation of bulky adducts in DNA and subsequent effects on DNA replication fork progression. Because there are many protein-protein and protein-DNA interactions proposed to be involved in activation and/or maintenance of ATR-Chk1 signaling in vivo, we systematically analyzed the association of a number of ATR-Chk1 pathway proteins with relevant checkpoint-inducing DNA structures in vitro. These DNA substrates included single-stranded DNA, branched DNA, and bulky adduct-containing DNA. We found that many checkpoint proteins show a preference for single-stranded, branched, and bulky adduct-containing DNA in comparison to undamaged, double-stranded DNA. We additionally found that the association of checkpoint proteins with bulky DNA damage relative to undamaged DNA was strongly influenced by the ionic strength of the binding reaction. Interestingly, among the checkpoint proteins analyzed the checkpoint mediator proteins Tipin and Claspin showed the greatest differential affinity for checkpoint-inducing DNA structures. We conclude that the association and accumulation of multiple checkpoint proteins with DNA structures indicative of DNA damage and replication stress likely contribute to optimal ATR-Chk1 DNA damage checkpoint responses

    Physicians' preference values for hepatitis C health states and antiviral therapy: A survey

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    BACKGROUND: Physicians' perspectives regarding hepatitis C shape their approach to patient management. We used utility analysis to evaluate physicians' perceptions of hepatitis C-related health states (HS) and their threshold to recommend treatment. METHODS: A written questionnaire was administered to practicing physicians. They were asked to rate hepatitis C health states on a visual analog scale ranging from 0% (death) to 100% (health without hepatitis C). Physicians then judged quality of life associated with the side effects of antiviral therapy for hepatitis C and indicated the sustained virological response rate that they would require to recommend treatment. RESULTS: One hundred and thirteen physicians from five states were included. Median utility ratings for hepatitis C health states declined significantly with increasing severity of symptoms: HS1-No Symptoms, No Cirrhosis (88%; 12% reduction from good health), HS2-Mild Symptoms, No Cirrhosis (66%), HS3-Moderate Symptoms, No Cirrhosis (49%), HS4-Mild Symptoms, Cirrhosis (40%), HS5-Severe Symptoms, Cirrhosis (18%) [p < 0.001]. The median rating for life with side effects of antiviral therapy was 47%, suggesting a 53% reduction from good health. That was similar to the utility value for HS3-Moderate Symptoms, No Cirrhosis. The median threshold value for recommending treatment was a sustained response rate of 60%. CONCLUSIONS: 1) Physicians' utility ratings for hepatitis C health states were inversely related to the severity of disease manifestations described. 2) Physicians viewed side effects of therapy unfavorably and indicated that on average, they would require a 60% sustained response rate before recommending treatment, which far exceeds the efficacy of current antiviral therapy for hepatitis C in the majority of patients

    Synthesis, structural and magnetic characterization of lead-metaniobate/cobalt-ferrite nanocomposite films deposited by pulsed laser ablation

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    Detailed structural, microstructural and magnetic measurements were performed on (PbNb2O6)(1-x) -(CoFe2O4) (x) nanocomposite thin films deposited by laser ablation on Si(001)\Pt substrates, with different cobalt ferrite concentrations. The tuning of the lead concentration, due to the lead volatility, was found to be particularly important in order to obtain the orthorhombic (ferroelectric) lead niobate phase. The lattice parameter of CoFe2O4 was below the bulk value, indicating the presence of compressive strains on this phase. A magnetic anisotropy was observed, which favored the orientation of the magnetization in the direction perpendicular to the plane of the films, for cobalt ferrite concentrations 40-50 %. The shape, stress and magnetocrystalline anisotropy fields on the composites were calculated and compared. It was found that the perpendicular magnetic anisotropy was induced by the presence of strain on the ferrite phase in the films.- This work has been supported by Fundacao para a Ciencia e Tecnologia (FCT) and FEDER, through the projects POCI/CTM/60181/2004 and PTDC/CTM/099415/2008. J. Barbosa and I. T. Gomes gratefully acknowledge Ph.D. grants from Fundacao para a Ciencia e Tecnologia (SFRH/BD/41913/2007 and SFRH/BD/36348/2007, respectively).info:eu-repo/semantics/publishedVersio

    Plasmodium falciparum Malaria Endemicity in Indonesia in 2010

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    BACKGROUND: Malaria control programs require a detailed understanding of the contemporary spatial distribution of infection risk to efficiently allocate resources. We used model based geostatistics (MBG) techniques to generate a contemporary map of Plasmodium falciparum malaria risk in Indonesia in 2010. METHODS: Plasmodium falciparum Annual Parasite Incidence (PfAPI) data (2006-2008) were used to map limits of P. falciparum transmission. A total of 2,581 community blood surveys of P. falciparum parasite rate (PfPR) were identified (1985-2009). After quality control, 2,516 were included into a national database of age-standardized 2-10 year old PfPR data (PfPR(2-10)) for endemicity mapping. A Bayesian MBG procedure was used to create a predicted surface of PfPR(2-10) endemicity with uncertainty estimates. Population at risk estimates were derived with reference to a 2010 human population count surface. RESULTS: We estimate 132.8 million people in Indonesia, lived at risk of P. falciparum transmission in 2010. Of these, 70.3% inhabited areas of unstable transmission and 29.7% in stable transmission. Among those exposed to stable risk, the vast majority were at low risk (93.39%) with the reminder at intermediate (6.6%) and high risk (0.01%). More people in western Indonesia lived in unstable rather than stable transmission zones. In contrast, fewer people in eastern Indonesia lived in unstable versus stable transmission areas. CONCLUSION: While further feasibility assessments will be required, the immediate prospects for sustained control are good across much of the archipelago and medium term plans to transition to the pre-elimination phase are not unrealistic for P. falciparum. Endemicity in areas of Papua will clearly present the greatest challenge. This P. falciparum endemicity map allows malaria control agencies and their partners to comprehensively assess the region-specific prospects for reaching pre-elimination, monitor and evaluate the effectiveness of future strategies against this 2010 baseline and ultimately improve their evidence-based malaria control strategies

    The development of an intervention programme to reduce whole-body vibration exposure at work induced by a change in behaviour: a study protocol

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    <p>Abstract</p> <p>Background</p> <p>Whole body vibration (WBV) exposure at work is common and studies found evidence that this exposure might cause low back pain (LBP). A recent review concluded there is a lack of evidence of effective strategies to reduce WBV exposure. Most research in this field is focussed on the technical implications, although changing behaviour towards WBV exposure might be promising as well. Therefore, we developed an intervention programme to reduce WBV exposure in a population of drivers with the emphasis on a change in behaviour of driver and employer. The hypothesis is that an effective reduction in WBV exposure, in time, will lead to a reduction in LBP as WBV exposure is a proxy for an increased risk of LBP.</p> <p>Methods/Design</p> <p>The intervention programme was developed specifically for the drivers of vibrating vehicles and their employers. The intervention programme will be based on the most important determinants of WBV exposure as track conditions, driving speed, quality of the seat, etc. By increasing knowledge and skills towards changing these determinants, the attitude, social influence and self-efficacy (ASE) of both drivers and employers will be affected having an effect on the level of exposure. We used the well-known ASE model to develop an intervention programme aiming at a change or the intention to change behaviour towards WBV exposure. The developed programme consists of: individual health surveillance, an information brochure, an informative presentation and a report of the performed field measurements.</p> <p>Discussion</p> <p>The study protocol described is advantageous as the intervention program actively tries to change behaviour towards WBV exposure. The near future will show if this intervention program is effective by showing a decrease in WBV exposure.</p

    Diagnostic delay for giant cell arteritis – a systematic review and meta-analysis

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    Background Giant cell arteritis (GCA), if untreated, can lead to blindness and stroke. The study’s objectives were to (1) determine a new evidence-based benchmark of the extent of diagnostic delay for GCA and (2) examine the role of GCA-specific characteristics on diagnostic delay. Methods Medical literature databases were searched from inception to November 2015. Articles were included if reporting a time-period of diagnostic delay between onset of GCA symptoms and diagnosis. Two reviewers assessed the quality of the final articles and extracted data from these. Random-effects meta-analysis was used to pool the mean time-period (95% confidence interval (CI)) between GCA symptom onset and diagnosis, and the delay observed for GCA-specific characteristics. Heterogeneity was assessed by I 2 and by 95% prediction interval (PI). Results Of 4128 articles initially identified, 16 provided data for meta-analysis. Mean diagnostic delay was 9.0 weeks (95% CI, 6.5 to 11.4) between symptom onset and GCA diagnosis (I 2 = 96.0%; P < 0.001; 95% PI, 0 to 19.2 weeks). Patients with a cranial presentation of GCA received a diagnosis after 7.7 (95% CI, 2.7 to 12.8) weeks (I 2 = 98.4%; P < 0.001; 95% PI, 0 to 27.6 weeks) and those with non-cranial GCA after 17.6 (95% CI, 9.7 to 25.5) weeks (I 2 = 96.6%; P < 0.001; 95% PI, 0 to 46.1 weeks). Conclusions The mean delay from symptom onset to GCA diagnosis was 9 weeks, or longer when cranial symptoms were absent. Our research provides an evidence-based benchmark for diagnostic delay of GCA and supports the need for improved public awareness and fast-track diagnostic pathways

    Peptide Substrates for Rho-Associated Kinase 2 (Rho-Kinase 2/ROCK2)

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    Peptide substrates sensitive for a certain protein kinase could be important for new-drug development and to understand the mechanism of diseases. Rho-associated kinase (Rho-kinase/ROCK) is a serine/threonine kinase, and plays an important part in cardiovascular disease, migration and invasion of tumor cells, and in neurological disorders. The purpose of this study was to find substrates with high affinity and sensitivity for ROCK2. We synthesized 136 peptide substrates from protein substrates for ROCK2 with different lengths and charged peptides. Incorporation of 32P [counts per minute (CPM)] for each peptide substrate was determined by the radiolabel assay using [γ-32P]ATP. When the top five peptide substrates showing high CPMs (R4, R22, R133, R134, and R135) were phosphorylated by other enzymes (PKA, PKCα, and ERK1), R22, R133, and R135 displayed the highest CPM level for ROCK2 compared with other enzymes, whereas R4 and R134 showed similar CPM levels for ROCK2 and PKCα. We hypothesize that R22, R133, and R135 can be useful peptide substrates for ROCK2
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