4,996 research outputs found

    Optical Pumping of TeH+: Implications for the Search for Varying mp/me

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    Molecular overtone transitions provide optical frequency transitions sensitive to variation in the proton-to-electron mass ratio (μmp/me\mu\equiv m_p/m_e). However, robust molecular state preparation presents a challenge critical for achieving high precision. Here, we characterize infrared and optical-frequency broadband laser cooling schemes for TeH+^+, a species with multiple electronic transitions amenable to sustained laser control. Using rate equations to simulate laser cooling population dynamics, we estimate the fractional sensitivity to μ\mu attainable using TeH+^+. We find that laser cooling of TeH+^+ can lead to significant improvements on current μ\mu variation limits

    Relativistic quantum dynamics of scalar bosons under a full vector Coulomb interaction

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    The relativistic quantum dynamics of scalar bosons in the background of a full vector coupling (minimal plus nonminimal vector couplings) is explored in the context of the Duffin-Kemmer-Petiau formalism. The Coulomb phase shift is determined for a general mixing of couplings and it is shown that the space component of the nonminimal coupling is a {\it sine qua non} condition for the exact closed-form scattering amplitude. It follows that the Rutherford cross section vanishes in the absence of the time component of the minimal coupling. Bound-state solutions obtained from the poles of the partial scattering amplitude show that the time component of the minimal coupling plays an essential role. The bound-state solutions depend on the nonminimal coupling and the spectrum consists of particles or antiparticles depending on the sign of the time component of the minimal coupling without chance for pair production even in the presence of strong couplings. It is also shown that an accidental degeneracy appears for a particular mixing of couplings.Comment: 8 pages, 1 table. arXiv admin note: text overlap with arXiv:1403.603

    On the Numerical Accuracy of Spreadsheets

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    This paper discusses the numerical precision of five spreadsheets (Calc, Excel, Gnumeric, NeoOffice and Oleo) running on two hardware platforms (i386 and amd64) and on three operating systems (Windows Vista, Ubuntu Intrepid and Mac OS Leopard). The methodology consists of checking the number of correct significant digits returned by each spreadsheet when computing the sample mean, standard deviation, first-order autocorrelation, F statistic in ANOVA tests, linear and nonlinear regression and distribution functions. A discussion about the algorithms for pseudorandom number generation provided by these platforms is also conducted. We conclude that there is no safe choice among the spreadsheets here assessed: they all fail in nonlinear regression and they are not suited for Monte Carlo experiments.

    Effects of endoscopic thoracic sympathectomy for primary hyperhidrosis on cardiac autonomic nervous activity

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    ObjectiveEndoscopic thoracic sympathectomy is performed to treat primary hyperhidrosis. The second and third sympathetic thoracic ganglia excised also innervate the heart. Some studies have shown decreased heart rate but have not been conclusive regarding other cardiac effects of sympathectomy. We studied the cardiac autonomic effects of endoscopic thoracic sympathectomy in a group of patients with primary hyperhidrosis. Heart rate variability is a simple, noninvasive electrocardiographic marker reflecting the activity and balance of the sympathetic and vagal components of the autonomous nervous system.MethodsWe performed a prospective study in 38 patients with primary hyperhidrosis with 24-hour Holter recordings obtained before endoscopic thoracic sympathectomy and 6 months later.ResultsWe found statistically significant differences (P < .05) in both time and frequency domains. Parameters that evaluate global cardiac autonomic activity (total power, SD of normal R-R intervals, SD of average normal R-R intervals) and vagal activity (rhythm corresponding to percentage of normal R-R intervals with cycle greater than 50 ms relative to previous interval, square root of mean squared differences of successive normal R-R intervals, high-frequency power, high-frequency power in normalized units) were statistically significantly increased after sympathectomy. Low-frequency power in normalized units, reflecting sympathetic activity, was statistically significantly decreased after sympathectomy. Low-/high-frequency power ratio also showed a significant decrease, indicating relative decrease in sympathetic activity and increase in vagal activity.ConclusionThese results provide, for the first time to our knowledge, clear evidence of increased vagal and global cardiac autonomic activity and decreased sympathetic activity after endoscopic thoracic sympathectomy

    Sequential Organ Failure Assessment Score for Evaluating Organ Failure and Outcome of Severe Maternal Morbidity in Obstetric Intensive Care

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    Objective. To evaluate the performance of Sequential Organ Failure Assessment (SOFA) score in cases of severe maternal morbidity (SMM). Design. Retrospective study of diagnostic validation. Setting. An obstetric intensive care unit (ICU) in Brazil. Population. 673 women with SMM. Main Outcome Measures. mortality and SOFA score. Methods. Organ failure was evaluated according to maximum score for each one of its six components. The total maximum SOFA score was calculated using the poorest result of each component, reflecting the maximum degree of alteration in systemic organ function. Results. highest total maximum SOFA score was associated with mortality, 12.06 ± 5.47 for women who died and 1.87 ± 2.56 for survivors. There was also a significant correlation between the number of failing organs and maternal mortality, ranging from 0.2% (no failure) to 85.7% (≥3 organs). Analysis of the area under the receiver operating characteristic (ROC) curve (AUC) confirmed the excellent performance of total maximum SOFA score for cases of SMM (AUC = 0.958). Conclusions. Total maximum SOFA score proved to be an effective tool for evaluating severity and estimating prognosis in cases of SMM. Maximum SOFA score may be used to conceptually define and stratify the degree of severity in cases of SMM

    On the Numerical Accuracy of Spreadsheets

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    This paper discusses the numerical precision of five spreadsheets (Calc, Excel, Gnumeric, NeoOffice and Oleo) running on two hardware platforms (i386 and amd64) and on three operating systems (Windows Vista, Ubuntu Intrepid and Mac OS Leopard). The methodology consists of checking the number of correct significant digits returned by each spreadsheet when computing the sample mean, standard deviation, first-order autocorrelation, F statistic in ANOVA tests, linear and nonlinear regression and distribution functions. A discussion about the algorithms for pseudorandom number generation provided by these platforms is also conducted. We conclude that there is no safe choice among the spreadsheets here assessed: they all fail in nonlinear regression and they are not suited for Monte Carlo experiments

    Poredbene hematološke i biokemijske analize divovske amazonske kornjače uzgajane pod lošim i normalnim hranidbenim uvjetima

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    Besides indicating the baseline values of the species, blood parameter assessments of chelonian may also be used as quick tools for diagnosing health status. An investigation was carried out to assess and compare red blood cells parameters, white blood cell (WBC) and total thrombocyte counts and certain blood biochemical parameters for freshwater turtles, Podocnemis expansa Schweigger, 1812 (Pelomedusidae) reared on normal (control group) and poor nutrition (malnourished group). For the malnourished turtles, a signififi cant decrease (P<0.05) in red blood cell counts was found, including hematocrit, plasma glucose, plasma total protein, cholesterol and urea levels, as well as WBC counts, azurophils and heterophils. Malnutrition did not alter the hemostasis, but caused severe normocytic-hypocromic anemia and marked immune depression, which were diagnosed here. This study was the fifi rst to characterize the physiological and immune status of giant turtles from the Amazon under adverse nutritional conditions.Osim za utvrđivanje osnovnih vrijednosti osebujnih za vrstu, pretraživanje krvnih pokazatelja može u kornjača biti rabljeno za brzo određivanje njihova zdravstvenoga stanja. Istraživanje je poduzeto da se odrede i usporede pokazatelji crvenih krvnih stanica, bijelih krvnih stanica, ukupnog broja trombocita i neki biokemijski pokazatelji za slatkovodne kornjače Podocnemis expansa Schweigger, 1812 (Pelomedusidae) uzgajane u normalnim (kontrolna skupina) i lošim hranidbenim uvjetima (pokusna skupina). U kornjača uzgajanih u lošim uvjetima ustanovljen je značajno smanjen (P<0,05) broj crvenih krvnih stanica kao i smanjene vrijednosti hematokrita, razine glukoze u plazmi, razine ukupnih proteina plazme, kolesterola i mokraćevine te broj bijelih krvnih stanica, azurofila i heterofila. Loša hranidba nije utjecala na hemostazu, ali je prouzročila tešku normocitnu hipokromnu anemiju i znatnu imunodepresiju. Ovo je prvo istraživanje u kojem je prikazan fiziološki i imunološki status divovske kornjače iz Amazone, držane u nepovoljnim hranidbenim uvjetima
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