1,347 research outputs found
CHEMICALLY MODIFIED PHOTOSYNTHETIC BACTERIAL REACTION CENTERS: CIRCULAR DICHROISM, RAMAN RESONANCE, LOW TEMPERATURE ABSORPTION, FLUORESCENCE AND ODMR SPECTRA AND POLYPEPTIDE COMPOSITION OF BOROHYDRIDE TREATED REACTION CENTERS FROM Rhodobacter sphaeroides R26
Reaction centers from Rhodobacter sphaeroides have been modified by treatment with sodium borohydride similar to the original procedure [Ditson et al., Biochim. Biophys. Acta 766, 623 (1984)], and investigated spectroscopically and by gel electrophoresis.
(1) Low temperature (1.2 K) absorption, fluorescence, absorption- and fluorescence-detected ODMR, and microwave-induced singlet-triplet absorption difference spectra (MIA) suggest that the treatment produces a spectroscopically homogeneous preparation with one of the âadditionalâ bacteriochlorophylls being removed. The modification does not alter the zero field splitting parameters of the primary donor triplet (TP870).
(2) From the circular dichroism and Raman resonance spectra in the1500â1800 cm-1 region, the removed pigment is assigned to BchlM, e.g. the "extra" Bchl on the "inactive" M-branch.
(3) A strong coupling among all pigment molecules is deduced from the circular dichroism spectra, because pronounced band-shifts and/or intensity changes occur in the spectral components assigned to all pigments. This is supported by distinct differences among the MIA spectra of untreated and modified reaction centers, as well as by Raman resonance.
(4) The modification is accompanied by partial proteolytic cleavage of the M-subunit. The preparation is thus spectroscopically homogeneous, but biochemically heterogenous
Commitment to Breastfeeding in the Context of Phenylketonuria
Objective: To describe the meaning and importance of breastfeeding to mothers of infants with phenylketonuria (PKU).
Design: Qualitative description.
Setting: Mothers from the United States and Canada were recruited from the PKU Listserv and interviewed by telephone.
Participants: Ten breastfeeding mothers with infants who had PKU and were younger than age 36 months.
Methods: Mothersâ thoughts, decisions, and experiences of breastfeeding their infants with PKU were collected through telephone interviews. Interviews were transcribed verbatim, and data were analyzed using thematic descriptive analysis in the context of PKU.
Results: Participants felt that that breastfeeding an infant with PKU was the healthiest choice and was therefore worth the labor. These women believed that this was what a loving mother would choose. As they continued to breastfeed their infants after diagnosis, the views of the participants changed. Initially they saw PKU as a disorder and felt that their infants were ill; later they felt that their infants were healthy in spite of PKU. Normal could mean a breastfeeding infant with PKU.
Conclusion: Findings demonstrate the importance mothers attribute to breastfeeding and their willingness to invest considerable effort to breastfeed. Health care providers working with these mothers should help them strategize for success
Biogenic 2âmethylâ3âbutenâ2âol increases regional ozone and HO x sources
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95042/1/grl23505.pd
Preserving entanglement under decoherence and sandwiching all separable states
Every entangled state can be perturbed, for instance by decoherence, and stay
entangled. For a large class of pure entangled states, we show how large the
perturbation can be. Our class includes all pure bipartite and all maximally
entangled states. For an entangled state, E, the constucted neighborhood of
entangled states is the region outside two parallel hyperplanes, which sandwich
the set of all separable states. The states for which these neighborhoods are
largest are the maximally entangled ones. As the number of particles, or the
dimensions of the Hilbert spaces for two of the particles increases, the
distance between two of the hyperplanes which sandwich the separable states
goes to zero. It is easy to decide if a state Q is in the neighborhood of
entangled states we construct for an entangled state E. One merely has to check
if the trace of EQ is greater than a constant which depends upon E and which we
determine.Comment: Corrected first author's e-mail address. All the rest remains
unchange
Return to drug use and overdose after release from prison: a qualitative study of risk and protective factors
BACKGROUND: Former inmates are at high risk for death from drug overdose, especially in the immediate post-release period. The purpose of the study is to understand the drug use experiences, perceptions of overdose risk, and experiences with overdose among former prisoners. METHODS: This qualitative study included former prison inmates (N = 29) who were recruited within two months after their release. Interviewers conducted in-person, semi-structured interviews which explored participants' experiences and perceptions. Transcripts were analyzed utilizing a team-based method of inductive analysis. RESULTS: The following themes emerged: 1) Relapse to drugs and alcohol occurred in a context of poor social support, medical co-morbidity and inadequate economic resources; 2) former inmates experienced ubiquitous exposure to drugs in their living environments; 3) intentional overdose was considered "a way out" given situational stressors, and accidental overdose was perceived as related to decreased tolerance; and 4) protective factors included structured drug treatment programs, spirituality/religion, community-based resources (including self-help groups), and family. CONCLUSIONS: Former inmates return to environments that strongly trigger relapse to drug use and put them at risk for overdose. Interventions to prevent overdose after release from prison may benefit from including structured treatment with gradual transition to the community, enhanced protective factors, and reductions of environmental triggers to use drugs
Measuring the Spins of Accreting Black Holes
A typical galaxy is thought to contain tens of millions of stellar-mass black
holes, the collapsed remnants of once massive stars, and a single nuclear
supermassive black hole. Both classes of black holes accrete gas from their
environments. The accreting gas forms a flattened orbiting structure known as
an accretion disk. During the past several years, it has become possible to
obtain measurements of the spins of the two classes of black holes by modeling
the X-ray emission from their accretion disks. Two methods are employed, both
of which depend upon identifying the inner radius of the accretion disk with
the innermost stable circular orbit (ISCO), whose radius depends only on the
mass and spin of the black hole. In the Fe K method, which applies to both
classes of black holes, one models the profile of the
relativistically-broadened iron line with a special focus on the
gravitationally redshifted red wing of the line. In the continuum-fitting
method, which has so far only been applied to stellar-mass black holes, one
models the thermal X-ray continuum spectrum of the accretion disk. We discuss
both methods, with a strong emphasis on the continuum-fitting method and its
application to stellar-mass black holes. Spin results for eight stellar-mass
black holes are summarized. These data are used to argue that the high spins of
at least some of these black holes are natal, and that the presence or absence
of relativistic jets in accreting black holes is not entirely determined by the
spin of the black hole.Comment: To appear in Classical and Quantum Gravity; Special volume for GR19,
eds. D. Marolf and D. Sudarsky; 28 pages, 6 figures; Includes corrections
made to proofs, which are significant only for Section
The Galactic WN stars: Spectral analyses with line-blanketed model atmospheres versus stellar evolution models with and without rotation
CONTEXT: Very massive stars pass through the Wolf-Rayet (WR) stage before
they finally explode. Details of their evolution have not yet been safely
established, and their physics are not well understood. Their spectral analysis
requires adequate model atmospheres, which have been developed step by step
during the past decades and account in their recent version for line blanketing
by the millions of lines from iron and iron-group elements. However, only very
few WN stars have been re-analyzed by means of line-blanketed models yet.
AIMS: The quantitative spectral analysis of a large sample of Galactic WN
stars with the most advanced generation of model atmospheres should provide an
empirical basis for various studies about the origin, evolution, and physics of
the Wolf-Rayet stars and their powerful winds.
METHODS: We analyze a large sample of Galactic WN stars by means of the
Potsdam Wolf-Rayet (PoWR) model atmospheres, which account for iron line
blanketing and clumping. The results are compared with a synthetic population,
generated from the Geneva tracks for massive star evolution. RESULTS: We obtain
a homogeneous set of stellar and atmospheric parameters for the Galactic WN
stars, partly revising earlier results.
CONCLUSIONS: Comparing the results of our spectral analyses of the Galactic
WN stars with the predictions of the Geneva evolutionary calculations, we
conclude that there is rough qualitative agreement. However, the quantitative
discrepancies are still severe, and there is no preference for the tracks that
account for the effects of rotation. It seems that the evolution of massive
stars is still not satisfactorily understood.Comment: 19 pages, 11 figures, A&A, in press, additional Online-material on
http://www.astro.physik.uni-potsdam.de/abstracts/galwn.htm
Idarucizumab for Dabigatran Reversal - Full Cohort Analysis.
BACKGROUND: Idarucizumab, a monoclonal antibody fragment, was developed to reverse the anticoagulant effect of dabigatran.
METHODS: We performed a multicenter, prospective, open-label study to determine whether 5 g of intravenous idarucizumab would be able to reverse the anticoagulant effect of dabigatran in patients who had uncontrolled bleeding (group A) or were about to undergo an urgent procedure (group B). The primary end point was the maximum percentage reversal of the anticoagulant effect of dabigatran within 4 hours after the administration of idarucizumab, on the basis of the diluted thrombin time or ecarin clotting time. Secondary end points included the restoration of hemostasis and safety measures.
RESULTS: A total of 503 patients were enrolled: 301 in group A, and 202 in group B. The median maximum percentage reversal of dabigatran was 100% (95% confidence interval, 100 to 100), on the basis of either the diluted thrombin time or the ecarin clotting time. In group A, 137 patients (45.5%) presented with gastrointestinal bleeding and 98 (32.6%) presented with intracranial hemorrhage; among the patients who could be assessed, the median time to the cessation of bleeding was 2.5 hours. In group B, the median time to the initiation of the intended procedure was 1.6 hours; periprocedural hemostasis was assessed as normal in 93.4% of the patients, mildly abnormal in 5.1%, and moderately abnormal in 1.5%. At 90 days, thrombotic events had occurred in 6.3% of the patients in group A and in 7.4% in group B, and the mortality rate was 18.8% and 18.9%, respectively. There were no serious adverse safety signals.
CONCLUSIONS: In emergency situations, idarucizumab rapidly, durably, and safely reversed the anticoagulant effect of dabigatran. (Funded by Boehringer Ingelheim; RE-VERSE AD ClinicalTrials.gov number, NCT02104947 .)
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