2,035 research outputs found
Chiral corrections to the Gell-Mann-Oakes-Renner relation
The next to leading order chiral corrections to the
Gell-Mann-Oakes-Renner (GMOR) relation are obtained using the pseudoscalar
correlator to five-loop order in perturbative QCD, together with new finite
energy sum rules (FESR) incorporating polynomial, Legendre type, integration
kernels. The purpose of these kernels is to suppress hadronic contributions in
the region where they are least known. This reduces considerably the systematic
uncertainties arising from the lack of direct experimental information on the
hadronic resonance spectral function. Three different methods are used to
compute the FESR contour integral in the complex energy (squared) s-plane, i.e.
Fixed Order Perturbation Theory, Contour Improved Perturbation Theory, and a
fixed renormalization scale scheme. We obtain for the corrections to the GMOR
relation, , the value . This result
is substantially more accurate than previous determinations based on QCD sum
rules; it is also more reliable as it is basically free of systematic
uncertainties. It implies a light quark condensate . As a byproduct, the chiral perturbation theory (unphysical) low energy
constant is predicted to be , or .Comment: A comment about the value of the strong coupling has been added at
the end of Section 4. No change in results or conslusion
Corrections to the Gell-Mann-Oakes-Renner relation and chiral couplings and
Next to leading order corrections to the
Gell-Mann-Oakes-Renner relation (GMOR) are obtained using weighted QCD Finite
Energy Sum Rules (FESR) involving the pseudoscalar current correlator. Two
types of integration kernels in the FESR are used to suppress the contribution
of the kaon radial excitations to the hadronic spectral function, one with
local and the other with global constraints. The result for the pseudoscalar
current correlator at zero momentum is , leading to the chiral corrections to GMOR: . The resulting uncertainties are mostly due to variations in the upper
limit of integration in the FESR, within the stability regions, and to a much
lesser extent due to the uncertainties in the strong coupling and the strange
quark mass. Higher order quark mass corrections, vacuum condensates, and the
hadronic resonance sector play a negligible role in this determination. These
results confirm an independent determination from chiral perturbation theory
giving also very large corrections, i.e. roughly an order of magnitude larger
than the corresponding corrections in chiral . Combining
these results with our previous determination of the corrections to GMOR in
chiral , , we are able to determine two low
energy constants of chiral perturbation theory, i.e. , and , both at the
scale of the -meson mass.Comment: Revised version with minor correction
B meson decay constants f(Bc), f(Bs) and f(B) from QCD sum rules
Finite energy QCD sum rules with Legendre polynomial integration kernels are used to determine the heavy meson decay constant f(Bc), and revisit f(B) and f(Bs). Results exhibit excellent stability in a wide range of values of the integration radius in the complex squared energy plane, and of the order of the Legendre polynomial. Results are f(Bc) = 528 +/- 19 MeV, f(B) = 186 +/- 14 MeV, and f(Bs) = 222 +/- 12 MeV
Genetic diversity of Mycobacterium tuberculosis in Peru and exploration of phylogenetic associations with drug resistance.
BACKGROUND: There is limited available data on the strain diversity of M tuberculosis in Peru, though there may be interesting lessons to learn from a setting where multidrug resistant TB has emerged as a major problem despite an apparently well-functioning DOTS control programme. METHODS: Spoligotyping was undertaken on 794 strains of M tuberculosis collected between 1999 and 2005 from 553 community-based patients and 241 hospital-based HIV co-infected patients with pulmonary tuberculosis in Lima, Peru. Phylogenetic and epidemiologic analyses permitted identification of clusters and exploration of spoligotype associations with drug resistance. RESULTS: Mean patient age was 31.9 years, 63% were male and 30.4% were known to be HIV+. Rifampicin mono-resistance, isoniazid mono-resistance and multidrug resistance (MDR) were identified in 4.7%, 8.7% and 17.3% of strains respectively. Of 794 strains from 794 patients there were 149 different spoligotypes. Of these there were 27 strains (3.4%) with novel, unique orphan spoligotypes. 498 strains (62.7%) were clustered in the nine most common spoligotypes: 16.4% SIT 50 (clade H3), 12.3% SIT 53 (clade T1), 8.3% SIT 33 (LAM3), 7.4% SIT 42 (LAM9), 5.5% SIT 1 (Beijing), 3.9% SIT 47 (H1), 3.0% SIT 222 (clade unknown), 3.0% SIT1355 (LAM), and 2.8% SIT 92 (X3). Amongst HIV-negative community-based TB patients no associations were seen between drug resistance and specific spoligotypes; in contrast HIV-associated MDRTB, but not isoniazid or rifampicin mono-resistance, was associated with SIT42 and SIT53 strains. CONCLUSION: Two spoligotypes were associated with MDR particularly amongst patients with HIV. The MDR-HIV association was significantly reduced after controlling for SIT42 and SIT53 status; residual confounding may explain the remaining apparent association. These data are suggestive of a prolonged, clonal, hospital-based outbreak of MDR disease amongst HIV patients but do not support a hypothesis of strain-specific propensity for the acquisition of resistance-conferring mutations
Weinberg like sum rules revisited
The generalized Weinberg sum rules containing the difference of isovector
vector and axial-vector spectral functions saturated by both finite and
infinite number of narrow resonances are considered. We summarize the status of
these sum rules and analyze their overall agreement with phenomenological
Lagrangians, low-energy relations, parity doubling, hadron string models, and
experimental data.Comment: 31 pages, noticed misprints are corrected, references are added, and
other minor corrections are mad
Rates of depressive and anxiety symptoms in the perinatal period during the COVID-19 pandemic: Comparisons between countries and with pre-pandemic data
Background: The COVID-19 pandemic was a significant threat to perinatal mental health. This study examined differences in clinically significant depression, anxiety, and co-morbid symptoms among pregnant and postpartum women across several countries and compared prevalence of perinatal depression and anxiety before and during the pandemic in each participating country. Methods: Participants were 3326 pregnant and 3939 postpartum women (up to six months postpartum) living in Brazil, Chile, Cyprus, Greece, Israel, Portugal, Spain, Turkey, and the United Kingdom. An online survey was completed between June 7th and October 31st 2020, and included the Edinburgh Postnatal Depression Scale (EPDS) and the Generalized Anxiety Disorder Screener (GAD-7). The pre-pandemic studies were identified through literature review. Results: Prevalence of clinically significant depression (EPDS≥13), anxiety (GAD-7 ≥ 10), and co-morbid (EPDS≥13 and GAD-7 ≥ 10) symptoms was 26.7 %, 20 % and 15.2 %, in pregnant women, and 32.7 %, 26.6 % and 20.3 %, in postpartum women, respectively. Significant between-country differences were found in all mental health indicators in both perinatal periods. Higher levels of symptoms were observed during (versus before) the pandemic, especially among postpartum women. Limitations: Participants were mostly highly educated and cohabiting with a partner. The online nature of the survey may have limited the participation of women from vulnerable socio-economically backgrounds. Conclusions: Our findings expand previous literature on the negative impact of the COVID-19 pandemic on perinatal mental health, by highlighting that this may be influenced by country of residence. Mental health care policies and interventions should consider the unique needs of perinatal women in different parts of the world. © 2022Funding text 1: Sara Cruz acknowledges the Centro de Investigação em Psicologia para o Desenvolvimento (CIPD) [The Psychology for Positive Development Research Center] ( UID/PSI/04375 ), Lusíada University North, Porto, supported by national funds through the Portuguese Foundation for Science and Technology , I.P., and the Portuguese Ministry of Science, Technology and Higher Education ( UID/PSI/04375/2019 ).; Funding text 2: This paper is part of the COST Action Riseup-PPD CA18138 and was supported by COST under COST Action Riseup-PPD CA18138 . ; Funding text 3: Vera Mateus received financial support from CAPES /PrInt grant no. 88887.583508/2020-00 . ; Funding text 4: Raquel Costa was supported by the FSE and FCT under the Post-Doctoral Grant SFRH/BPD/117597/2016 [RC]. EPIUnit, ITR, and HEI-lab are supported by national funds through the Portuguese Foundation for Science and Technology , I.P., under the projects UIDB/04750/2020 , LA/P/0064/2020 , and UIDB/05380/2020 , respectively. ; Funding text 5: This publication is based upon work from COST Action 18138 - Research Innovation and Sustainable Pan-European Network in Peripartum Depression Disorder (Riseup-PPD), supported by COST (European Cooperation in Science and Technology). www.cost.eu . ; Funding text 6: Ana Osório received financial support from CAPES PROEX grant no. 0426/2021 , process no. 23038.006837/2021-73, CAPES /PrInt grant no. 88887.310343/2018-00 and MackPesquisa Fund . ; Funding text 7: Rena Bina received financial support from the Bar-Ilan Dangoor Centre for Personalized Medicine , grant no. REFU/DANGO/100. ; Funding text 8: This publication is based upon work from COST Action 18138 - Research Innovation and Sustainable Pan-European Network in Peripartum Depression Disorder (Riseup-PPD), supported by COST (European Cooperation in Science and Technology). www.cost.eu.Vera Mateus received financial support from CAPES/PrInt grant no. 88887.583508/2020-00.Ana Osório received financial support from CAPES PROEX grant no. 0426/2021, process no. 23038.006837/2021-73, CAPES/PrInt grant no. 88887.310343/2018-00 and MackPesquisa Fund.Rena Bina received financial support from the Bar-Ilan Dangoor Centre for Personalized Medicine, grant no. REFU/DANGO/100.Raquel Costa was supported by the FSE and FCT under the Post-Doctoral Grant SFRH/BPD/117597/2016 [RC]. EPIUnit, ITR, and HEI-lab are supported by national funds through the Portuguese Foundation for Science and Technology, I.P., under the projects UIDB/04750/2020, LA/P/0064/2020, and UIDB/05380/2020, respectively.This paper is part of the COST Action Riseup-PPD CA18138 and was supported by COST under COST Action Riseup-PPD CA18138. The authors would like to thank all women who participated in the survey. Sara Cruz acknowledges the Centro de Investigação em Psicologia para o Desenvolvimento (CIPD) [The Psychology for Positive Development Research Center] (UID/PSI/04375), Lusíada University North, Porto, supported by national funds through the Portuguese Foundation for Science and Technology, I.P. and the Portuguese Ministry of Science, Technology and Higher Education (UID/PSI/04375/2019)
Bisphenol A exposure in Mexico City and risk of prematurity: a pilot nested case control study
Abstract Background Presence of Bisphenol A (BPA) has been documented worldwide in a variety of human biological samples. There is growing evidence that low level BPA exposure may impact placental tissue development and thyroid function in humans. The aim of this present pilot study was to determine urinary concentrations of BPA during the last trimester of pregnancy among a small subset of women in Mexico City, Mexico and relate these concentrations to risk of delivering prematurely. Methods A nested case-control subset of 60 participants in the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) study in Mexico City, Mexico were selected based on delivering less than or equal to 37 weeks of gestation and greater than 37 weeks of gestation. Third trimester archived spot urine samples were analyzed by online solid phase extraction coupled with high performance liquid chromatography isotope dilution tandem mass spectrometry. Results BPA was detected in 80.0% (N = 48) of the urine samples; total concentrations ranged from < 0.4 μg/L to 6.7 μg/L; uncorrected geometric mean was 1.52 μg/L. The adjusted odds ratio of delivering less than or equal to 37 weeks in relation to specific gravity adjusted third trimester BPA concentration was 1.91 (95%CI 0.93, 3.91, p-value = 0.08). When cases were further restricted to births occurring prior to the 37th week (n = 12), the odds ratio for specific-gravity adjusted BPA was larger and statistically significant (p < 0.05). Conclusions This is the first study to document measurable levels of BPA in the urine of a population of Mexican women. This study also provides preliminary evidence, based on a single spot urine sample collected during the third trimester, that pregnant women who delivered less than or equal to 37 weeks of gestation and prematurely (< 37 weeks) had higher urinary concentrations of BPA compared to women delivering after 37 weeks.http://deepblue.lib.umich.edu/bitstream/2027.42/78251/1/1476-069X-9-62.xmlhttp://deepblue.lib.umich.edu/bitstream/2027.42/78251/2/1476-069X-9-62.pdfPeer Reviewe
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