116 research outputs found

    Coupling of Nonlocal Potentials to Electromagnetic Fields

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    Nonlocal Hamiltonians are used widely in first-principles quantum calculations; the nonlocality stems from eliminating undesired degrees of freedom, e.g. core electrons. To date, attempts to couple nonlocal systems to external electromagnetic (EM) fields have been heuristic or limited to weak or long wavelength fields. Using Feynman path integrals, we derive an exact, closed-form coupling of arbitrary EM fields to nonlocal systems. Our results justify and clarify the couplings used to date and are essential for systematic computation of linear and especially nonlinear response.Comment: 1 figure, 1 tabl

    Doppler echocardiography assessment of impaired left ventricular filling in patients with right ventricular pressure overload due to primary pulmonary hypertension

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    In patients with primary pulmonary hypertension, competition between the right and left ventricles for the limited pericardial space results in distortion of left ventricular geometry reflected in displacement of the ventricular septum toward the left ventricular cavity. Left ventricular shape is most dramatically deranged at end-systole and early diastole, suggesting the possibility that the distribution of left ventricular diastolic filling might be altered. To investigate this hypothesis, nine patients with primary pulmonary hypertension and nine normal individuals were studied with echocardiographic techniques. Left ventricular isovolumic relaxation time was significantly prolonged in patients with primary pulmonary hypertension by comparison with normal individuals (129 ± 36 versus 53 ± 9 ms, p < 0.005) and the fraction of the transmitral flow velocity integral occurring in the first half of diastole was significantly less than in normal individuals (38 ± 14% versus 70 ± 9%, p < 0.005). Measurement of fractional changes in short-axis left ventricular cavity area similarly demonstrated that in patients with primary pulmonary hypertension fractional early diastolic cavity expansion (32 ± 11%) was significantly less than in normal individuals (78 ± 9%, p < 0.005).In patients with primary pulmonary hypertension, the ventricular septum was abnormally flattened toward the left ventricular cavity at end-systole (normalized septal curvature 0.04 ± 0.19) and remained that way throughout early diastolic filling but returned toward normal at end-diastole (normalized septal curvature 0.68 ± 0.19, p < 0.005). Thus, in patients with primary pulmonary hypertension end-systolic and early diastolic deformation of the left ventricle by septal flattening toward the left ventricular cavity is associated with relative underfilling of the left ventricle in early diastole and redistribution of left ventricular filling into late diastole. The reliance on late diastolic filling and atrial systole to maintain left ventricular preload in primary pulmonary hypertension may have important implications for the use of vasodilators in this disease

    Doppler echocardiographic demonstration of the differential effects of right ventricular pressure and volume overload on left ventricular geometry and filling

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    AbstractTo compare the effects of isolated right ventricular pressure and volume overload on left ventricular diastolic geometry and filling, 11 patients with primary pulmonary hypertension, 11 patients with severe tricuspid regurgitation due to tricuspid valve resection and 11 normal subjects were studied with use of Doppler echocardiography techniques. Right ventricular systolic overload in primary pulmonary hypertension resulted in substantial leftword ventricular septal shift that was most marked at end-systole and early diastole and decreased substantially by end-diastole. Right ventricular diastolic overload after tricuspid valve resection resulted in maximal leftward ventricular septal shift at end-diastole sparing end-systole and early diastole. The early diastolic distortion of left ventricular geometry associated with right ventricular pressure overload resulted in prolongation of isovolumetric relaxation of the left ventricle (129 ± 39 ms) and a reduction in early diastolic finding compared with values in normal subjects.Late diastolic distortion of left ventricular geometry associated with right ventricular volume overload had no influence on the duration of left ventricular isovolumetric relaxatoon (52 ± 32 ms) but caused a reduction in the atrial systolic contribution to late distolic filling of the left ventricle compared with values in normal sujects. In patients with right ventricular pressure overload, 52 ± 16% of left ventricular filling occurred in early diastole compared with 78 ± 11% in patients with right ventricular volume overload (p < 0.001). The differential effects of systolic and diastolic right ventricular overload on the pattern of left ventricular filling appear to bt related to the timing of leftward ventricular septal displacement

    Reduced atrial contribution to left ventricular filling in patients with severe tricuspid regurgitation after tricuspid valvulectomy: A Doppler echocardiographic study

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    AbstractPatients undergoing valvulectomy for isolated tricuspid valve endocarditis offer the unique opportunity to study the effects of acquired right ventricular volume overload on left ventricular filling in persons free of pulmonary hypertension and preexisting left heart disease. Eleven patients who had undergone total or partial removal of the tricuspid valve were compared with 11 age-matched control subjects; Doppler echocardiographic techniques were used to quantify changes in left ventricular filling and to relate them to changes in left ventricular and left atrial geometry caused by right ventricular and right atrial distension.The late diastolic fractional transmitral flow velocity integral, a measure of the left atrial contribution to left ventricular filling, was significantly decreased in patients undergoing tricuspid valvulectomy compared with control subjects (0.22 ± 0.11 versus 0.32 ± 0.09; p < 0.04). Severe tricuspid regurgitation in these patients resulted in marked right atrial distension, reversal of the normal interatrial septal curvature and compression of the left atrium such that left atrial area was significantly smaller than in control subjects (5.9 ± 2.2 versus 8.6 ± 1.2 cm2/m2; p < 0.005).Acting as a receiving chamber, the left ventricle was maximally compressed by the volume-overloaded right ventricle in late diastole coincident with the timing of atrial systole, resulting in a significant increase in the left ventricular eccentricity index compared with that in control subjects (1.35 ± 0.14 versus 1.03 ± 0.1; p < 0.001). Thus, right ventricular volume overload due to severe tricuspid regurgitation results in left heart geometric alterations that decrease left atrial preload, impair left ventricular receiving chamber characteristics and reduce the atrial contribution to total left ventricular filling

    Hypofractionated stereotactic radiotherapy for intracranial meningioma: A systematic review

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    Background: The availability of image guidance and intensity modulation has led to the increasing use of hypofractionated stereotactic radiotherapy (hSRT) as an alternative to conventionally fractionated radiotherapy or radiosurgery for intracranial meningiomas (ICMs). As the safety and efficacy of this approach is not well characterized, we conducted a systematic review of the literature to assess the clinical outcomes of hSRT in the setting of ICMs. Methods: A systematic review of Medline and EMBASE databases was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies were retrospective or prospective series that examined an ICM population of ≄10 patients, delivered \u3e1 fraction of photon hSRT (≄2.5 Gy per fraction), and had a median follow-up of ≄2 years. Descriptive statistics were generated for included studies. Results: Of 1480 initial studies, 14 met eligibility criteria for inclusion, reporting on 630 patients (age range, 18-90) treated for 638 tumors. Primary radiotherapy was delivered in 37% of patients, 36% had radiation following surgery, and surgical details were unavailable for 27%. In 474 tumors assessed for radiologic response, 78% remained stable, 18% decreased in size, and 4% increased in size. Crude local control was 90%-100% as reported in 10 studies. The median late toxicity rate was 10%. The most common significant late toxicities were decreased visual acuity and new cranial neuropathy. Conclusions: With limited follow-up, the available literature suggests hSRT for ICMs has local control and toxicity profiles comparable to other radiotherapy approaches. Confirmation in larger patient cohorts with a longer duration of follow-up is required

    Patient-reported reasons for declining or discontinuing statin therapy: Insights from the PALM registry

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    Background: Many adults eligible for statin therapy for cardiovascular disease prevention are untreated. Our objective was to investigate patient‐reported reasons for statin underutilization, including noninitiation, refusal, and discontinuation.Methods and Results: This study included the 5693 adults recommended for statin therapy in the PALM (Patient and Provider Assessment of Lipid Management) registry. Patient surveys evaluated statin experience, reasons for declining or discontinuing statins, and beliefs about statins and cardiovascular disease risk. Overall, 1511 of 5693 adults (26.5%) were not on treatment. Of those not on a statin, 894 (59.2%) reported never being offered a statin, 153 (10.1%) declined a statin, and 464 (30.7%) had discontinued therapy. Women (relative risk: 1.22), black adults (relative risk: 1.48), and those without insurance (relative risk: 1.38) were most likely to report never being offered a statin. Fear of side effects and perceived side effects were the most common reasons cited for declining or discontinuing a statin. Compared with statin users, those who declined or discontinued statins were less likely to believe statins are safe (70.4% of current users vs. 36.9% of those who declined and 37.4% of those who discontinued) or effective (86.3%, 67.4%, and 69.1%, respectively). Willingness to take a statin was high; 67.7% of those never offered and 59.7% of patients who discontinued a statin would consider initiating or retrying a statin.Conclusions: More than half of patients eligible for statin therapy but not on treatment reported never being offered one by their doctor. Concern about side effects was the leading reason for statin refusal or discontinuation. Many patients were willing to reconsider statin therapy if offered

    GWAS of QRS Duration Identifies New Loci Specific to Hispanic/Latino Populations

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    BACKGROUND: The electrocardiographically quantified QRS duration measures ventricular depolarization and conduction. QRS prolongation has been associated with poor heart failure prognosis and cardiovascular mortality, including sudden death. While previous genome-wide association studies (GWAS) have identified 32 QRS SNPs across 26 loci among European, African, and Asian-descent populations, the genetics of QRS among Hispanics/Latinos has not been previously explored. METHODS: We performed a GWAS of QRS duration among Hispanic/Latino ancestry populations (n = 15,124) from four studies using 1000 Genomes imputed genotype data (adjusted for age, sex, global ancestry, clinical and study-specific covariates). Study-specific results were combined using fixed-effects, inverse variance-weighted meta-analysis. RESULTS: We identified six loci associated with QRS (P CONCLUSIONS: Our QRS duration GWAS, the first in Hispanic/Latino populations, identified two new loci, underscoring the utility of extending large scale genomic studies to currently under-examined populations

    The RIP140 Gene Is a Transcriptional Target of E2F1

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    RIP140 is a transcriptional coregulator involved in energy homeostasis and ovulation which is controlled at the transcriptional level by several nuclear receptors. We demonstrate here that RIP140 is a novel target gene of the E2F1 transcription factor. Bioinformatics analysis, gel shift assay, and chromatin immunoprecipitation demonstrate that the RIP140 promoter contains bona fide E2F response elements. In transiently transfected MCF-7 breast cancer cells, the RIP140 promoter is transactivated by overexpression of E2F1/DP1. Interestingly, RIP140 mRNA is finely regulated during cell cycle progression (5-fold increase at the G1/S and G2/M transitions). The positive regulation by E2F1 requires sequences located in the proximal region of the promoter (−73/+167), involves Sp1 transcription factors, and undergoes a negative feedback control by RIP140. Finally, we show that E2F1 participates in the induction of RIP140 expression during adipocyte differentiation. Altogether, this work identifies the RIP140 gene as a new transcriptional target of E2F1 which may explain some of the effect of E2F1 in both cancer and metabolic diseases

    A Framework for Prioritizing the TESS Planetary Candidates Most Amenable to Atmospheric Characterization

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    A key legacy of the recently launched TESS mission will be to provide the astronomical community with many of the best transiting exoplanet targets for atmospheric characterization. However, time is of the essence to take full advantage of this opportunity. JWST, although delayed, will still complete its nominal five year mission on a timeline that motivates rapid identification, confirmation, and mass measurement of the top atmospheric characterization targets from TESS. Beyond JWST, future dedicated missions for atmospheric studies such as ARIEL require the discovery and confirmation of several hundred additional sub-Jovian size planets (R_p < 10 R_Earth) orbiting bright stars, beyond those known today, to ensure a successful statistical census of exoplanet atmospheres. Ground-based ELTs will also contribute to surveying the atmospheres of the transiting planets discovered by TESS. Here we present a set of two straightforward analytic metrics, quantifying the expected signal-to-noise in transmission and thermal emission spectroscopy for a given planet, that will allow the top atmospheric characterization targets to be readily identified among the TESS planet candidates. Targets that meet our proposed threshold values for these metrics would be encouraged for rapid follow-up and confirmation via radial velocity mass measurements. Based on the catalog of simulated TESS detections by Sullivan et al. (2015), we determine appropriate cutoff values of the metrics, such that the TESS mission will ultimately yield a sample of ∌300\sim300 high-quality atmospheric characterization targets across a range of planet size bins, extending down to Earth-size, potentially habitable worlds.Comment: accepted to PAS
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