4,413 research outputs found

    Improved variables for measuring the LambdabLambda_b polarization

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    We discuss a few possible strategies for measuring the polarization of the Λb\Lambda_{\mathrm{b}} baryons produced in e+ee^+e^--annihilation at the Z\mathrm{Z} resonance through their inclusive semileptonic decays. After reviewing the existing methods, a new method is proposed, based on the ratio of the averages of the squared electron and neutrino energy, including both perturbative and nonperturbative corrections. This variable minimizes the statistical error on the Λb\Lambda_{\mathrm{b}} polarization, while keeping the systematic theoretical errors at the level of 1-2%. A number of other polarization-sensitive variables are also discussed, such as averages of ratios of the electron and neutrino energy and the distribution in the difference of the electron and neutrino rapidities.Comment: 23 pages, 4 uuencoded figures, REVTe

    The third moment of quadratic Dirichlet L-functions

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    We study the third moment of quadratic Dirichlet L-functions, obtaining an error term of size O(X3/4+ε)O(X^{3/4 + \varepsilon}).Comment: 27 pages. v2: modified a remark on p.

    Pelvic floor disorders in gynecological malignancies. An overlooked problem?

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    Cervical, endometrial, ovarian, vulvar, and vaginal cancers affect women of a broad age spectrum. Many of these women are still sexually active when their cancer is diagnosed. Treatment options for gynecological malignancies, such as gynecological surgery, radiation, and chemotherapy, are proven risk factors for pelvic floor dysfunction. The prevalence of urinary incontinence, fecal incontinence, and sexual dysfunction before cancer treatment is still unclear. Hypotheses have been raised in the literature that these manifestations could represent early symptoms of pelvic cancers, but most remain overlooked even in cancer surviving patients. The primary focus of therapy is always cancer eradication, but as oncological and surgical treatment options become more successful, the number of cancer survivors increases. The quality of life of patients with gynecological cancers often remains an underrated subject. Pelvic floor disorders are not consistently reported by patients and are frequently overlooked by many clinicians. In this brief review we discuss the importance of pelvic floor dysfunction in patients with gynecological malignant tumors

    Pheochromocytoma – clinical manifestations, diagnosis and current perioperative management

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    Pheochromocytoma is a neuroendocrine tumor characterized by the excessive production of catecholamines (epinephrine, norepinephrine, and dopamine). The diagnosis is suspected due to hypertensive paroxysms, associated with vegetative phenomena, due to the catecholaminergic hypersecretion. Diagnosis involves biochemical tests that reveal elevated levels of catecholamine metabolites (metanephrine and normetanephrine). Functional imaging, such as 123I-metaiodobenzylguanidine scintigraphy (123I-MIBG), has increased specificity in identifying the catecholamine-producing tumor and its metastases. The gold-standard treatment for patients with pheochromocytoma is represented by the surgical removal of the tumor. Before surgical resection, it is important to optimize blood pressure and intravascular volume in order to avoid negative hemodynamic events

    Accurate Hartree-Fock energy of extended systems using large Gaussian basis sets

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    Calculating highly accurate thermochemical properties of condensed matter via wave function-based approaches (such as e.g. Hartree-Fock or hybrid functionals) has recently attracted much interest. We here present two strategies providing accurate Hartree-Fock energies for solid LiH in a large Gaussian basis set and applying periodic boundary conditions. The total energies were obtained using two different approaches, namely a supercell evaluation of Hartree-Fock exchange using a truncated Coulomb operator and an extrapolation toward the full-range Hartree-Fock limit of a Pad\'e fit to a series of short-range screened Hartree-Fock calculations. These two techniques agreed to significant precision. We also present the Hartree-Fock cohesive energy of LiH (converged to within sub-meV) at the experimental equilibrium volume as well as the Hartree-Fock equilibrium lattice constant and bulk modulus.Comment: 7.5 pages, 2 figures, submitted to Phys. Rev. B; v2: typos removed, References adde

    Mott Transition of MnO under Pressure: Comparison of Correlated Band Theories

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    The electronic structure, magnetic moment, and volume collapse of MnO under pressure are obtained from four different correlated band theory methods; local density approximation + Hubbard U (LDA+U), pseudopotential self-interaction correction (pseudo-SIC), the hybrid functional (combined local exchange plus Hartree-Fock exchange), and the local spin density SIC (SIC-LSD) method. Each method treats correlation among the five Mn 3d orbitals (per spin), including their hybridization with three O 2p2p orbitals in the valence bands and their changes with pressure. The focus is on comparison of the methods for rocksalt MnO (neglecting the observed transition to the NiAs structure in the 90-100 GPa range). Each method predicts a first-order volume collapse, but with variation in the predicted volume and critical pressure. Accompanying the volume collapse is a moment collapse, which for all methods is from high-spin to low-spin (5/2 to 1/2), not to nonmagnetic as the simplest scenario would have. The specific manner in which the transition occurs varies considerably among the methods: pseudo-SIC and SIC-LSD give insulator-to-metal, while LDA+U gives insulator-to-insulator and the hybrid method gives an insulator-to-semimetal transition. Projected densities of states above and below the transition are presented for each of the methods and used to analyze the character of each transition. In some cases the rhombohedral symmetry of the antiferromagnetically ordered phase clearly influences the character of the transition.Comment: 14 pages, 9 figures. A 7 institute collaboration, Updated versio

    Cardio metabolic risk factors for atrial fibrillation in type 2 diabetes mellitus: Focus on hypertension, metabolic syndrome and obesity

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    Objective. Atrial fibrillation (AF) in type 2 diabetes mellitus (T2DM) has been little explored so far. However, there are several cardio metabolic risk factors for AF in T2DM patients, such as arterial hypertension, obesity or the metabolic syndrome. Our objective was to evaluate cardio metabolic risk factors for AF in T2DM patients. Methods. We studied the medical records of T2DM patients hospitalized in the Internal Medicine department of an emergency referral hospital in Bucharest, Romania. The study was observational, retrospective and carried out between January-June 2018. Results. The study group included 221 T2DM patients (with a mean age of 68.65 ± 10.64, ranging between 37-93 years): 116 women (52.49%; with a mean age of 70.53 ± 10.69, ranging between 37-93 years) and 105 men (47.51%; with a mean age of 66.57 ± 10.23, ranging between 38-91 years). 92 patients had AF (41.63%): 40 women (34.48%) and 52 men (49.52%). 180 patients (81.45%) were hypertensive: 103 women (88.79%) and 77 men (73.33%). 113 patients (51.13%) had metabolic syndrome: 58 women (50.00%) and 55 men (52.38%). 77 patients (34.84%) were obese: 45 women (38.79%) and 32 men (30.48%). AF patients associated obesity in 26 cases (28.26%), hypertension in 73 cases (79.35%) and metabolic syndrome in 56 cases (60.87%). Conclusions. Out of the study group, 92 T2DM patients (41.63%) had AF, men being more likely to suffer from AF than women (p=0.0288). Hypertension affected 180 patients (81.45%) and in greater proportion women vs. men (p=0.0051). The metabolic syndrome and obesity were discovered in 113 patients (51.13%) and 77 patients (34.84%), respectively, with no significant differences in terms of gender. In our research, the highest cardio metabolic risk factors for AF in T2DM were hypertension (OR = 3.6675) and the metabolic syndrome (OR = 3.3388)

    Determination of pyrrolizidine alkaloids in dietary sources using a spectrophotometric method

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    Pyrrolizidine alkaloids (PAs) are a class of toxic compounds found in the composition of more than 6000 plants. People can be exposed to PAs by consuming phytotherapeutic products, food from crops contaminated with seeds of some species with high content of PAs, and/ or contaminated animal products like bee products. For this reason we developed and validated a method for quantitative determination of PAs, from the most frequently contaminated food sources, honey and flour. Colorimetric Ehrlich reagent method was used with standard addition (1mg/kg senecionine). The extraction solvent was methanol 50% acidified with citric acid to pH 2-3, as this solvent can be used for alkaloids and N-oxides. We found that, in extracting the alkaloid only once from the dietary sources, the percent of recovery is low (52.5% for honey, and 45.75% for flour). Using successive extractions, three times with the same solvent, the senecionine retrieval percentage increased to 86.0% for honey and 76.0% for flour. The method was validated using the following parameters: selectivity, linearity (0,25- 20 mg/ mL senecionine), accuracy (average recovery 93.5 - 107.93%) and precision (RSD 3,26-4.55%.). The calculated limit of quantification (0.174 mg/ mL) makes this method applicable for determining Pas occurring at toxic levels for consumers
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