311 research outputs found

    The manifest association structure of the single-factor model: insights from partial correlations

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    The association structure between manifest variables arising from the single-factor model is investigated using partial correlations. The additional insights to the practitioner provided by partial correlations for detecting a single-factor model are discussed. The parameter space for the partial correlations is presented, as are the patterns of signs in a matrix containing the partial correlations that are not compatible with a single-factor model

    Chiral dynamics of p-wave in K^- p and coupled states

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    We perform an evaluation of the p-wave amplitudes of meson-baryon scattering in the strangeness S=-1 sector starting from the lowest order chiral Lagrangians and introducing explicitly the Sigma^* field with couplings to the meson-baryon states obtained using SU(6) symmetry. The N/D method of unitarization is used, equivalent, in practice, to the use of the Bethe-Salpeter equation with a cut-off. The procedure leaves no freedom for the p-waves once the s-waves are fixed and thus one obtains genuine predictions for the p-wave scattering amplitudes, which are in good agreement with experimental results for differential cross sections, as well as for the width and partial decay widths of the Sigma^*(1385).Comment: LaTeX, 18 pages, 6 figure

    Physics, Topology, Logic and Computation: A Rosetta Stone

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    In physics, Feynman diagrams are used to reason about quantum processes. In the 1980s, it became clear that underlying these diagrams is a powerful analogy between quantum physics and topology: namely, a linear operator behaves very much like a "cobordism". Similar diagrams can be used to reason about logic, where they represent proofs, and computation, where they represent programs. With the rise of interest in quantum cryptography and quantum computation, it became clear that there is extensive network of analogies between physics, topology, logic and computation. In this expository paper, we make some of these analogies precise using the concept of "closed symmetric monoidal category". We assume no prior knowledge of category theory, proof theory or computer science.Comment: 73 pages, 8 encapsulated postscript figure

    The coordinated action of VCP/p97 and GCN2 regulates cancer cell metabolism and proteostasis during nutrient limitation

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    VCP/p97 regulates numerous cellular functions by mediating protein degradation through its segregase activity. Its key role in governing protein homoeostasis has made VCP/p97 an appealing anticancer drug target. Here, we provide evidence that VCP/p97 acts as a regulator of cellular metabolism. We found that VCP/p97 was tied to multiple metabolic processes on the gene expression level in a diverse range of cancer cell lines and in patient-derived multiple myeloma cells. Cellular VCP/p97 dependency to maintain proteostasis was increased under conditions of glucose and glutamine limitation in a range of cancer cell lines from different tissues. Moreover, glutamine depletion led to increased VCP/p97 expression, whereas VCP/p97 inhibition perturbed metabolic processes and intracellular amino acid turnover. GCN2, an amino acid-sensing kinase, attenuated stress signalling and cell death triggered by VCP/p97 inhibition and nutrient shortages and modulated ERK activation, autophagy, and glycolytic metabolite turnover. Together, our data point to an interconnected role of VCP/p97 and GCN2 in maintaining cancer cell metabolic and protein homoeostasis

    Inflation and Brane Gases

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    We investigate a new way of realizing a period of cosmological inflation in the context of brane gas cosmology. It is argued that a gas of co-dimension one branes, out of thermal equilibrium with the rest of the matter, has an equation of state which can - after stabilization of the dilaton - lead to power-law inflation of the bulk. The most promising implementation of this mechanism might be in Type IIB superstring theory, with inflation of the three large spatial dimensions triggered by ``stabilized embedded 2-branes''. Possible applications and problems with this proposal are discussed.Comment: 7 pages, uses REVTeX, version to appear in Phys. Rev.

    Stochastic Production Of Kink-Antikink Pairs In The Presence Of An Oscillating Background

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    We numerically investigate the production of kink-antikink pairs in a (1+1)(1+1) dimensional ϕ4\phi^4 field theory subject to white noise and periodic driving. The twin effects of noise and periodic driving acting in conjunction lead to considerable enhancement in the kink density compared to the thermal equilibrium value, for low dissipation coefficients and for a specific range of frequencies of the oscillating background. The dependence of the kink-density on the temperature of the heat bath, the amplitude of the oscillating background and value of the dissipation coefficient is also investigated. An interesting feature of our result is that kink-antikink production occurs even though the system always remains in the broken symmetry phase.Comment: Revtex, 21 pages including 7 figures; more references adde

    Rescattering and chiral dynamics in B\to \rho\pi decay

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    We examine the role of B^0(\bar B^0) \to \sigma \pi^0 \to \pi^+\pi^- \pi^0 decay in the Dalitz plot analysis of B^0 (\bar B^0) \to \rho\pi \to \pi^+\pi^-\pi^0 decays, employed to extract the CKM parameter \alpha. The \sigma \pi channel is significant because it can break the relationship between the penguin contributions in B\to\rho^0\pi^0, B\to\rho^+\pi^-, and B\to\rho^-\pi^+ decays consequent to an assumption of isospin symmetry. Its presence thus mimics the effect of isospin violation. The \sigma\pi^0 state is of definite CP, however; we demonstrate that the B\to\rho\pi analysis can be generalized to include this channel without difficulty. The \sigma or f_0(400-1200) ``meson'' is a broad I=J=0 enhancement driven by strong \pi\pi rescattering; a suitable scalar form factor is constrained by the chiral dynamics of low-energy hadron-hadron interactions - it is rather different from the relativistic Breit-Wigner form adopted in earlier B\to\sigma\pi and D\to\sigma\pi analyses. We show that the use of this scalar form factor leads to an improved theoretical understanding of the measured ratio Br(\bar B^0 \to \rho^\mp \pi^\pm) / Br(B^-\to \rho^0 \pi^-).Comment: 26 pages, 8 figs, published version. typos fixed, minor change

    Association of community engagement with vaccination confidence and uptake: A cross-sectional survey in Sierra Leone, 2019

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    Background The 2014-2016 Ebola epidemic disrupted childhood immunization in Sierra Leone, Liberia, and Guinea. After the epidemic, the Government of Sierra Leone prioritized community engagement to increase vaccination confidence and uptake. To support these efforts, we examined potential drivers of vaccination confidence and uptake in Sierra Leone. Methods We conducted a population-based household survey with primary caregivers of children in a birth cohort of 12 to 23 months in four districts with low vaccination coverage in Sierra Leone in 2019. Modified Poisson regression modeling with robust variance estimation was used to examine if perceived community engagement in planning the immunization program in the community was associated with vaccination confidence and having a fully vaccinated child. Results The sample comprised 621 age-eligible children and their caregivers (91% response rate). Half of the caregivers (52%) reported that it usually takes too long to get to the vaccination site, and 36% perceived that health workers expect money for vaccination services that are supposed to be given at no charge. When mothers were the decision-makers of the children’s vaccination, 80% of the children were fully vaccinated versus 69% when fathers were the decision-makers and 56% when other relatives were the decision-makers. Caregivers with high confidence in vaccination were more likely to have fully vaccinated children compared to caregivers with low confidence (78% versus 53%). For example, caregivers who thought vaccines are ‘very much’ safe were more likely to have fully vaccinated children than those who thought vaccines are ‘somewhat’ safe (76% versus 48%). Overall, 53% of caregivers perceived high level of community engagement, 41% perceived medium level of engagement, and 6% perceived low level of engagement. Perceiving high community engagement was associated with expressing high vaccination confidence (adjusted prevalence ratio (aPR) = 2.60; 95% confidence interval (CI) = 1.67-4.04) and having a fully vaccinated child (aPR = 1.67; 95% CI = 1.18-2.38). Conclusions In these four low coverage districts in Sierra Leone, the perceived level of community engagement was strongly associated with vaccination confidence among caregivers and vaccination uptake among children. We have provided exploratory cross-sectional evidence to inform future longitudinal assessments to further investigate the potential causal effect of community engagement on vaccination confidence and uptake

    Maintenance lenalidomide in newly diagnosed transplant eligible and non-eligible myeloma patients; profiling second primary malignancies in 4358 patients treated in the Myeloma XI Trial

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    Background: Early trials of long-term lenalidomide use reported an increased incidence of second primary malignancy (SPM), including acute myeloid leukaemia and myelodysplastic syndrome. Later, meta-analysis suggested the link to be secondary to lenalidomide in combination with melphalan. Methods: Myeloma XI is a large, phase III randomised trial in-which lenalidomide was used at induction and maintenance, in transplant eligible (TE) and non-eligible (TNE) newly diagnosed patients (NCT01554852). Here we present an analysis of SPM incidence and profile the SPM type to determine the impact of autologous stem cell transplantation (ASCT) and lenalidomide exposure in 4358 patients treated on study. Data collection took place from the start of the trial in May 2010, to May 2019, as per the protocol timeline. The Median follow-up following maintenance randomisation was 54.5 and 46.1 months for TE and TNE patients, respectively. Findings: In the TE pathway, the overall SPM incidence was 7.7% in lenalidomide maintenance patients compared to 3.2% in those being observed (p = 0.006). Although the TNE lenalidomide maintenance patients had the greatest SPM incidence (15.4%), this was not statistically significant when compared to the observed patients (10%, p = 0.10). The SPM incidence was higher in patients who received lenalidomide at induction and maintenance (double exposure), when compared to those treated with lenalidomide at one time point (single exposure). Again, this was most marked in TNE patients where the overall SPM incidence was 16.9% in double exposed patients, compared to 11.7% in single exposed patients, and 11.2% in patients who did not receive lenalidomide (p = 0.04). This is likely an effect of treatment duration, with the median number of cycles being 27 in the TNE double exposed patients, vs 6 in the single exposure patients. Haematological SPMs were uncommon, diagnosed in 50 patients (incidence 1.1%). The majority of cases were diagnosed in TE patients treated with lenalidomide maintenance (n = 25, incidence 2.8%), suggesting a possible link with melphalan. Non-melanoma skin cancer incidence was highest in patients receiving lenalidomide maintenance, particularly in TNE patients, where squamous cell carcinoma and basal cell carcinoma were diagnosed in 5.5% and 2.6% of patients, respectively. The incidence of most solid tumour types was higher in lenalidomide maintenance patients. Mortality due to progressive myeloma was reduced in patients receiving lenalidomide maintenance, noted to be 16.6% compared 22.6% in those observed in TE patients and 32.7% compared to 41.5% in TNE patients. SPM related mortality was low, 1.8% and 6.1% in TE and TNE lenalidomide maintenance patients, respectively, compared to 0.4% and 2.8% in those being observed. Interpretation: This provides reassurance that long-term lenalidomide treatment is safe and associated with improved outcomes in TE and TNE populations, although monitoring for SPM development should be incorporated into clinic review processes. Funding: Primary financial support was from Cancer Research UK [ C1298/A10410]

    The state of the Martian climate

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    60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes
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