699 research outputs found

    Experimental investigation of evolving anisotropy in unsaturated soils

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    This paper investigates the ‘initial’ and ‘evolving’ mechanical anisotropy of a compacted unsaturated soil. Awide campaign of triaxial compression and extension tests, involving different stress and suction paths, has been performed on both isotropically and anisotropically compacted samples of unsaturated Speswhite kaolin. The first objective is the definition of the initial yield surface of the compacted soil after suction equalisation and before any plastic loading/wetting path takes place. This is followed by the investigation of the evolution of the yield surface induced by plastic straining along different loading/wetting paths. Experimental results are interpreted by using two alternative stress variables, namely net stresses σij and Bishop’s stress Ïƒïżœ ij ÂŒ σij ĂŸ ÎŽijSrs (where ÎŽij is Kronecker delta, Sr is the degree of saturation and s is suction). Constant suction cross-sections of the yield surface are represented as distorted ellipses not passing through the origin in the q:p plane of deviator stress plotted against mean net stress, and by distorted ellipses passing through the origin in the q:p* plane of deviator stress plotted against mean Bishop’s stress. The inclination of these distorted elliptical yield curves evolves with plastic straining but remains the same at all suction levels for a given level of plastic deformation. The critical state lines in the planes q:p and q:p*, or in the semi-logarithmic v:lnp and v:lnp* planes (v is the specific volume), are generally independent of initial anisotropy or stress history, suggesting that fabric memory tends to be erased at critical state

    Genetic diversity and phylogenetic relationships within Eucalyptus marginata (Myrtaceae)

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    The eucalypt species Eucalyptus marginata which is harvested for high quality timber comprises three subspecies recognized by morphological characters; E. marginata ssp. marginata, ssp. thalassica, and ssp. elegantella. Genetic diversity and phylogenetic relationships between the subspecies were examined using anonymous nuclear RFLP loci, with Eucalyptus staerei included as an outgroup in the phylogenetic analysis. The level of diversity within the nuclear genome was lower than that found in comparative studies with other eucalypts (A = 2. 7, H4 = 0.345). Most of the variation occurred with ill the populations (96. 9%, H4 = 0.334) The two populations sampled for each of ssp. thalassica and ssp. elegantella clustered together in the UPGMA analysis, however there was little differentiation between the three subspecies overall (D = 0.029). Eucalyptus marginata was clearly distinct from its closest relative E. staerei (0 = 0.16). There is little genetic support for the separation of the subspecies

    Adherence to Endocrine Therapy and Racial Outcome Disparities in Breast Cancer

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    The disparity in outcomes of breast cancer for Black compared with White women in the U.S. is well known and persistent over time, with the largest disparities appearing among women with hormone receptor-positive (HR+) cancers. The racial gap in breast cancer survival first emerged in the 1980s, a time of significantmen treatment advances in early-stage breast cancer, including the introduction of adjuvant endocrine therapy. Since that time, the gap has continued to widen despite steady advances in treatment and survival of breast cancer overall. Although advanced stage at presentation and unfavorable biology undoubtedly contribute to racial differences in survival of HR+ breast, treatment disparities are increasingly acknowledged to play a key role as well. The recent recognition of racial differences in endocrine therapy use may be a key explanatory factor in the persistent racial gap in mortality of HR+ disease, and may be a key focus of intervention to improve breast cancer outcomes for Black women. Implications for Practice: Black women with hormone receptor–positive breast cancer experience the greatest racial disparity in survival among all breast cancer subtypes. This survival gap appears consistently across studies and is not entirely explained by differences in presenting stage, tumor biology as assessed by genomic risk scores, or receipt of chemotherapy. Recent research highlights lower adherence to endocrine therapy (ET) for Black women. Health systems and individual providers should focus on improving communication about the importance of ET use, sharing decisions around ET, providing appropriate support for side effects and other ET-related concerns, and equitably delivering survivorship care, including ET adherence assessment

    Factors Associated with Endocrine Therapy Non-Adherence in Breast Cancer Survivors

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    Background: For women with hormone receptor positive breast cancer, long-term endocrine therapy (ET) can greatly reduce the risk of recurrence, yet adherence is low- particularly among traditionally underserved populations. Methods: The Carolina Breast Cancer Study oversampled Black and young women (<50 years of age). Participants answered an ET-specific medication adherence questionnaire assessing reasons for non-adherence. We used principal factor analysis to identify latent factors describing ET non-adherence. We then performed multivariable regression to determine clinical and demographic characteristics associated with each ET non-adherence factor. Results: 1,231 women were included in analysis, 59% reported at least one barrier to ET adherence. We identified three latent factors which we defined as: habit - challenges developing medication-taking behavior; tradeoffs - high perceived side effect burden and medication safety concerns; and resource barriers - challenges related to cost or accessibility. Older age (50+) was associated with less reporting of habit (Adjusted Risk Ratio (aRR) 0.54[95% CI: 0.43-0.69] and resource barriers (aRR 0.66[0.43-0.997]), but was not associated with tradeoff barriers. Medicaid-insured women were more likely than privately-insured to report tradeoff (aRR:1.53 [1.10-2.13]) or resource barriers (aRR:4.43[2.49-6.57]). Black race was associated with increased reporting of all factors (habit: aRR 1.29[1.09-1.53]; tradeoffs: 1.32[1.09-1.60], resources: 1.65[1.18-2.30]). Conclusion: Barriers to ET adherence were described by three distinct factors, and strongly associated with sociodemographic characteristics. Barriers to ET adherence appear inadequately addressed for younger, Black, and publicly-insured breast cancer survivors. These findings underscore the importance of developing multi-faceted, patient-centered interventions that address a diverse range of barriers to ET adherence

    A review of size and geometrical factors influencing resonant frequencies in metamaterials

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    Although metamaterials and so-called left-handed media have originated from theoretical considerations, it is only by their practical fabrication and the measurement of their properties that they have gained credibility and can fulfil the potential of their predicted properties. In this review we consider some of the more generally applicable fabrication methods and changes in geometry as they have progressed, exhibiting resonant frequencies ranging from radio waves to the visible optical region

    Antiresonant hollow core fiber with an octave spanning bandwidth for short haul data communications

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    We report an effectively single mode tubular antiresonant hollow core fiber with minimum loss of ~25 dB/km at ~1200 nm, and an extremely wide low loss transmission window (lower than 30 dB/km loss from 1000 nm to 1400 nm and 6 dB bandwidth exceeding 1000 nm). Despite the relatively large mode field diameter of 32 ”m, the fiber can be interfaced to SMF28 to produce fully connectorized samples. Exploiting an excellent modal purity arising from large modal differential loss and low intermodal coupling, we demonstrate penalty-free 10G on-off keying data transmission through 100m of fiber, at wavelengths of 1065, 1565 and 1963nm

    Quasinormal modes for tensor and vector type perturbation of Gauss Bonnet black holes using third order WKB approach

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    We obtain the quasinormal modes for tensor perturbations of Gauss-Bonnet (GB) black holes in d=5,7,8d=5, 7, 8 dimensions and vector perturbations in d=5,6,7d = 5, 6, 7 and 8 dimensions using third order WKB formalism. The tensor perturbation for black holes in d=6d=6 is not considered because of the fact that it is unstable to tensor mode perturbations. In the case of uncharged GB black hole, for both tensor and vector perturbations, the real part of the QN frequency increases as the Gauss-Bonnet coupling (αâ€Č\alpha') increases. The imaginary part first decreases upto a certain value of αâ€Č\alpha' and then increases with αâ€Č\alpha' for both tensor and vector perturbations. For larger values of αâ€Č\alpha', the QN frequencies for vector perturbation differs slightly from the QN frequencies for tensorial one. It has also been shown that as αâ€Č→0\alpha' \to 0, the quasinormal mode frequency for tensor and vector perturbation of the Schwarzschild black hole can be obtained. We have also calculated the quasinormal spectrum of the charged GB black hole for tensor perturbations. Here we have found that the real oscillation frequency increases, while the imaginary part of the frequency falls with the increase of the charge. We also show that the quasinormal frequencies for scalar field perturbations and the tensor gravitational perturbations do not match as was claimed in the literature. The difference in the result increases if we increase the GB coupling.Comment: 17 pages, 11 figures, change in title and abstract, new equations and results added for QN frequencies for vector perturbations, new referencees adde

    Characterization of neutrino signals with radiopulses in dense media through the LPM effect

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    We discuss the possibilities of detecting radio pulses from high energy showers in ice, such as those produced by PeV and EeV neutrino interactions. It is shown that the rich radiation pattern structure in the 100 MHz to few GHz allows the separation of electromagnetic showers induced by photons or electrons above 100 PeV from those induced by hadrons. This opens up the possibility of measuring the energy fraction transmitted to the electron in a charged current electron neutrino interaction with adequate sampling of the angular distribution of the signal. The radio technique has the potential to complement conventional high energy neutrino detectors with flavor information.Comment: 5 pages, 4 ps figures. Submitted to Phys. Rev. Let

    Real-World Utilization of Oral Anticancer Agents and Related Costs in Older Adults with Metastatic Renal Cell Carcinoma in the United States

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    BACKGROUND: Substantial racial and socioeconomic disparities in metastatic RCC (mRCC) have persisted following the introduction of targeted oral anticancer agents (OAAs). The relationship between patient characteristics and OAA access and costs that may underlie persistent disparities in mRCC outcomes have not been examined in a nationally representative patient population. METHODS: Retrospective SEER-Medicare analysis of patients diagnosed with mRCC between 2007-2015 over age 65 with Medicare part D prescription drug coverage. Associations between patient characteristics, OAA receipt, and associated costs were analyzed in the 12 months following mRCC diagnosis and adjusted to 2015 dollars. RESULTS: 2,792 patients met inclusion criteria, of which 32.4%received an OAA. Most patients received sunitinib (57%) or pazopanib (28%) as their first oral therapy. Receipt of OAA did not differ by race/ethnicity or socioeconomic indicators. Patients of advanced age (>80 years), unmarried patients, and patients residing in the Southern US were less likely to receive OAAs. The mean inflation-adjusted 30-day cost to Medicare of a patient's first OAA prescription nearly doubled from 3864in2007to3864 in 2007 to 7482 in 2015, while patient out-of-pocket cost decreased from 2409to2409 to 1477. CONCLUSION: Race, ethnicity, and socioeconomic status were not associated with decreased OAA receipt in patients with mRCC; however, residing in the Southern United States was, as was marital status. Surprisingly, the cost to Medicare of an initial OAA prescription nearly doubled from 2007 to 2015, while patient out-of-pocket costs decreased substantially. Shifts in OAA costs may have significant economic implications in the era of personalized medicine
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