592 research outputs found
Challenging lanthanide relaxation theory: erbium and thulium complexes that show NMR relaxation rates faster than dysprosium and terbium analogues
Measurements of the proton NMR paramagnetic relaxation rates for several series of isostructural lanthanide(III) complexes have been performed in aqueous solution over the field range 1.0 to 16.5 Tesla. The field dependence has been modeled using Bloch–Redfield–Wangsness theory, allowing values for the electronic relaxation time, Tle and the magnetic susceptibility, μeff, to be estimated. Anomalous relaxation rate profiles were obtained, notably for erbium and thulium complexes of low symmetry 8-coordinate aza-phosphinate complexes. Such behaviour challenges accepted theory and can be interpreted in terms of changes in Tle values that are a function of the transient ligand field induced by solvent collision and vary considerably between Ln3+ ions, along with magnetic susceptibilities that deviate significantly from free-ion values
Patterns of Rotavirus Vaccine Uptake and Use in Privately-Insured US Infants, 2006-2010
Rotavirus vaccines are highly effective at preventing gastroenteritis in young children and are now universally recommended for infants in the US. We studied patterns of use of rotavirus vaccines among US infants with commercial insurance. We identified a large cohort of infants in the MarketScan Research Databases, 2006-2010. The analysis was restricted to infants residing in states without state-funded rotavirus vaccination programs. We computed summary statistics and used multivariable regression to assess the association between patient-, provider-, and ecologic-level variables of rotavirus vaccine receipt and series completion. Approximately 69% of 594,117 eligible infants received at least one dose of rotavirus vaccine from 2006-2010. Most infants received the rotavirus vaccines at the recommended ages, but more infants completed the series for monovalent rotavirus vaccine than pentavalent rotavirus vaccine or a mix of the vaccines (87% versus 79% versus 73%, P<0.001). In multivariable analyses, the strongest predictors of rotavirus vaccine series initiation and completion were receipt of the diphtheria, tetanus and acellular pertussis vaccine (Initiation: RR = 7.91, 95% CI = 7.69-8.13; Completion: RR = 1.26, 95% CI = 1.23-1.29), visiting a pediatrician versus family physician (Initiation: RR = 1.51, 95% CI = 1.49-1.52; Completion: RR = 1.13, 95% CI = 1.11-1.14), and living in a large metropolitan versus smaller metropolitan, urban, or rural area. We observed rapid diffusion of the rotavirus vaccine in routine practice; however, approximately one-fifth of infants did not receive at least one dose of vaccine as recently as 2010. Interventions to increase rotavirus vaccine coverage should consider targeting family physicians and encouraging completion of the vaccine series
Using claims data to predict dependency in activities of daily living as a proxy for frailty
Estimating drug effectiveness and safety among older adults in population-based studies using administrative health care claims can be hampered by unmeasured confounding as a result of frailty. A claims-based algorithm that identifies patients likely to be dependent, a proxy for frailty, may improve confounding control. Our objective was to develop an algorithm to predict dependency in activities of daily living (ADL) in a sample of Medicare beneficiaries. Methods: Community-dwelling respondents to the 2006 Medicare Current Beneficiary Survey, >65years old, with Medicare Part A, B, home health, and hospice claims were included. ADL dependency was defined as needing help with bathing, eating, walking, dressing, toileting, or transferring. Potential predictors were demographics, International Classification of Diseases, Ninth Revision Clinical Modification diagnosis/procedure and durable medical equipment codes for frailty-associated conditions. Multivariable logistic regression was used to predict ADL dependency. Cox models estimated hazard ratios for death as a function of observed and predicted ADL dependency. Results: Of 6391 respondents, 57% were female, 88% white, and 38% were ≥80. The prevalence of ADL dependency was 9.5%. Strong predictors of ADL dependency were charges for a home hospital bed (OR=5.44, 95%CI=3.28-9.03) and wheelchair (OR=3.91, 95%CI=2.78-5.51). The c-statistic of the final model was 0.845. Model-predicted ADL dependency of 20% or greater was associated with a hazard ratio for death of 3.19 (95%CI: 2.78, 3.68). Conclusions: An algorithm for predicting ADL dependency using health care claims was developed to measure some aspects of frailty. Accounting for variation in frailty among older adults could lead to more valid conclusions about treatment use, safety, and effectiveness
Association Between Gestational Diabetes and Incident Maternal CKD: The Coronary Artery Risk Development in Young Adults (CARDIA) Study
Background Gestational diabetes mellitus (GDM) is associated with increased risk for diabetes mellitus, metabolic syndrome, and cardiovascular disease. We evaluated whether GDM is associated with incident chronic kidney disease (CKD), controlling for prepregnancy risk factors for both conditions. Study Design Prospective cohort. Setting & Participants Of 2,747 women (aged 18-30 years) enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) Study in 1985 to 86, we studied 820 who were nulliparous at enrollment, delivered at least 1 pregnancy longer than 20 weeks’ gestation, and had kidney function measurements during 25 years of follow-up. Predictor GDM was self-reported by women for each pregnancy. Outcomes CKD was defined as the development of estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 or urine albumin-creatinine ratio ≥ 25 mg/g at any one CARDIA examination in years 10, 15, 20, or 25. Measurements HRs for developing CKD were estimated for women who developed GDM versus women without GDM using complementary log-log models, adjusting for prepregnancy age, systolic blood pressure, dyslipidemia, body mass index, smoking, education, eGFR, fasting glucose concentration, physical activity level (all measured at the CARDIA examination before the first pregnancy), race, and family history of diabetes. We explored for an interaction between race and GDM. Results During a mean follow-up of 20.8 years, 105 of 820 (12.8%) women developed CKD, predominantly increased urine albumin excretion (98 albuminuria only, 4 decreased eGFR only, and 3 both). There was evidence of a GDM-race interaction on CKD risk (P = 0.06). Among black women, the adjusted HR for CKD was 1.96 (95% CI, 1.04-3.67) in GDM compared with those without GDM. Among white women, the HR was 0.65 (95% CI, 0.23-1.83). Limitations Albuminuria was assessed by single untimed measurements of urine albumin and creatinine. Conclusions GDM is associated with the subsequent development of albuminuria among black women in CARDIA
Demystifying an unidentified EGRET source by VHE gamma-ray observations
In a novel approach in observational high-energy gamma-ray astronomy,
observations carried out by imaging atmospheric Cherenkov telescopes provide
necessary templates to pinpoint the nature of intriguing, yet unidentified
EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking
advantage of high spatial resolution images from H.E.S.S. observations, we were
able to shed new light on the EGRET observed gamma-ray emission in the
Kookaburra complex, whose previous coverage in the literature is somewhat
contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sources
(E>1 GeV), both in positional coincidence with the recently reported pulsar
wind nebulae (PWN) by HESS in the Kookaburra/Rabbit complex. PWN associations
at VHE energies, supported by accumulating evidence from observations in the
radio and X-ray band, are indicative for the PSR/plerionic origin of spatially
coincident, but still unidentified Galactic gamma-ray sources from EGRET. This
not only supports the already suggested connection between variable, but
unidentified low-latitude gamma-ray sources with pulsar wind nebulae
(3EGJ1420-6038 has been suggested as PWN candidate previoulsy), it also
documents the ability of resolving apparently confused EGRET sources by
connecting the GeV emission as measured from a large-aperture space-based
gamma-ray instrument with narrow field-of-view but superior spatial resolution
observations by ground-based atmospheric Cherenkov telescopes, a very promising
identification technique for achieving convincing individual source
identifications in the era of GLAST-LAT.Comment: 4 pages, 5 figures, Accepted for publication in Astrophysics and
Space Science, Proc. of "The Multi-Messenger Approach to High-Energy
Gamma-ray Sources (Third Workshop on the Nature of Unidentified High-Energy
Sources)", Barcelona, July 4-7, 2006, one typo correcte
A new measurement of direct CP violation in two pion decays of the neutral kaon
The NA48 experiment at CERN has performed a new measurement of direct CP
violation, based on data taken in 1997 by simultaneously collecting K_L and K_S
decays into pi0pi0 and pi+pi-. The result for the CP violating parameter
Re(epsilon'/epsilon) is (18.5 +/- 4.5(stat)} +/- 5.8 (syst))x10^{-4}.Comment: 18 pages, 6 figure
Determination of the Deep Inelastic Contribution to the Generalised Gerasimov-Drell-Hearn Integral for the Proton and Neutron
The virtual photon absorption cross section differences [sigma_1/2-sigma_3/2]
for the proton and neutron have been determined from measurements of polarised
cross section asymmetries in deep inelastic scattering of 27.5 GeV
longitudinally polarised positrons from polarised 1H and 3He internal gas
targets. The data were collected in the region above the nucleon resonances in
the kinematic range nu < 23.5 GeV and 0.8 GeV**2 < Q**2 < 12 GeV**2. For the
proton the contribution to the generalised Gerasimov-Drell-Hearn integral was
found to be substantial and must be included for an accurate determination of
the full integral. Furthermore the data are consistent with a QCD
next-to-leading order fit based on previous deep inelastic scattering data.
Therefore higher twist effects do not appear significant.Comment: 6 pages, 3 figures, 1 table, revte
Observation of a Coherence Length Effect in Exclusive Rho^0 Electroproduction
Exclusive incoherent electroproduction of the rho^0(770) meson from 1H, 2H,
3He, and 14N targets has been studied by the HERMES experiment at squared
four-momentum transfer Q**2>0.4 GeV**2 and positron energy loss nu from 9 to 20
GeV. The ratio of the 14N to 1H cross sections per nucleon, known as the
nuclear transparency, was found to decrease with increasing coherence length of
quark-antiquark fluctuations of the virtual photon. The data provide clear
evidence of the interaction of the quark- antiquark fluctuations with the
nuclear medium.Comment: RevTeX, 5 pages, 3 figure
Measurement of the Proton Spin Structure Function g1p with a Pure Hydrogen Target
A measurement of the proton spin structure function g1p(x,Q^2) in
deep-inelastic scattering is presented. The data were taken with the 27.6 GeV
longitudinally polarised positron beam at HERA incident on a longitudinally
polarised pure hydrogen gas target internal to the storage ring. The kinematic
range is 0.021<x<0.85 and 0.8 GeV^2<Q^2<20 GeV^2. The integral
Int_{0.021}^{0.85} g1p(x)dx evaluated at Q0^2 of 2.5 GeV^2 is
0.122+/-0.003(stat.)+/-0.010(syst.).Comment: 7 pages, 3 figures, 1 table, RevTeX late
Measurement of the Neutron Spin Structure Function with a Polarized ^3He Target
Results are reported from the HERMES experiment at HERA on a measurement of
the neutron spin structure function in deep inelastic scattering
using 27.5 GeV longitudinally polarized positrons incident on a polarized
He internal gas target. The data cover the kinematic range
and . The integral evaluated at a fixed of is . Assuming Regge behavior at low , the first
moment is .Comment: 4 pages TEX, text available at
http://www.krl.caltech.edu/preprints/OAP.htm
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