930 research outputs found
Q-band electron nuclear double resonance (ENDOR) and X-band EPR of the sulfobetaine 12 heat-treated cytochrome c oxidase complex
Heat treatment of the bovine cytochrome c oxidase complex in the zwitterionic detergent sulfobetaine 12 (SB-12) results in loss of subunit III and the appearance of a type II copper center as characterized by electron paramagnetic resonance (EPR) spectroscopy. Previous authors (Nilsson, T., Copeland, R. A., Smith, P. A., and Chan, S. I. (1988) Biochemistry 27, 8254-8260) have interpreted this type II copper center as a modified version of the CuA site. By using electron nuclear double resonance spectroscopy, it is found that the CuA proton and nitrogen resonances remain present in the SB-12 heat-treated enzyme and that three new nitrogen resonances appear having hyperfine coupling constants consistent with histidine ligation. These hyperfine coupling constants correlate well with those recently found for the CuB histidines from the cytochrome aa3-600 quinol oxidase from Bacillus subtilis (Fann, Y. C., Ahmed, I., Blackburn, N. J., Boswell, J. S., Verkhovskaya, M. L., Hoffman, B. M., and Wikström, M. (1995) Biochemistry 34, 10245-10255). In addition, the total EPR-detectable copper concentration per enzyme molecule approximately doubles upon SB-12 heat treatment. Finally, the observed type II copper EPR spectrum is virtually indistinguishable from the EPR spectrum of CuB of the as-isolated cytochrome bo3 complex from Escherichia coli. These data indicate that the type II copper species that appears results from a breaking of the strong antiferromagnetic coupling of the heme a3-CuB binuclear center
Recommended from our members
Health benefits and control costs of tightening particulate matter emissions standards for coal power plants - The case of Northeast Brazil.
Exposure to ambient particulate matter (PM) caused an estimated 4.2 million deaths worldwide in 2015. However, PM emission standards for power plants vary widely. To explore if the current levels of these standards are sufficiently stringent in a simple cost-benefit framework, we compared the health benefits (avoided monetized health costs) with the control costs of tightening PM emission standards for coal-fired power plants in Northeast (NE) Brazil, where ambient PM concentrations are below World Health Organization (WHO) guidelines. We considered three Brazilian PM10 (PMx refers to PM with a diameter under x micrometers) emission standards and a stricter U.S. EPA standard for recent power plants. Our integrated methodology simulates hourly electricity grid dispatch from utility-scale power plants, disperses the resulting PM2.5, and estimates selected human health impacts from PM2.5 exposure using the latest integrated exposure-response model. Since the emissions inventories required to model secondary PM are not available in our study area, we modeled only primary PM so our benefit estimates are conservative. We found that tightening existing PM10 emission standards yields health benefits that are over 60 times greater than emissions control costs in all the scenarios we considered. The monetary value of avoided hospital admissions alone is at least four times as large as the corresponding control costs. These results provide strong arguments for considering tightening PM emission standards for coal-fired power plants worldwide, including in regions that meet WHO guidelines and in developing countries
Association between 5-Year clinical outcome in patients with nonmedically evacuated mild blast traumatic brain injury and clinical measures collected within 7 days postinjury in combat
Importance: Although previous work has examined clinical outcomes in combat-deployed veterans, questions remain regarding how symptoms evolve or resolve following mild blast traumatic brain injury (TBI) treated in theater and their association with long-term outcomes.
Objective: To characterize 5-year outcome in patients with nonmedically evacuated blast concussion compared with combat-deployed controls and understand what clinical measures collected acutely in theater are associated with 5-year outcome.
Design, Setting, and Participants: A prospective, longitudinal cohort study including 45 service members with mild blast TBI within 7 days of injury (mean 4 days) and 45 combat deployed nonconcussed controls was carried out. Enrollment occurred in Afghanistan at the point of injury with evaluation of 5-year outcome in the United States. The enrollment occurred from March to September 2012 with 5-year follow up completed from April 2017 to May 2018. Data analysis was completed from June to July 2018.
Exposures: Concussive blast TBI. All patients were treated in theater, and none required medical evacuation.
Main Outcomes and Measures: Clinical measures collected in theater included measures for concussion symptoms, posttraumatic stress disorder (PTSD) symptoms, depression symptoms, balance performance, combat exposure intensity, cognitive performance, and demographics. Five-year outcome evaluation included measures for global disability, neurobehavioral impairment, PTSD symptoms, depression symptoms, and 10 domains of cognitive function. Forward selection multivariate regression was used to determine predictors of 5-year outcome for global disability, neurobehavior impairment, PTSD, and cognitive function.
Results: Nonmedically evacuated patients with concussive blast injury (n = 45; 44 men, mean [SD] age, 31 [5] years) fared poorly at 5-year follow-up compared with combat-deployed controls (n = 45; 35 men; mean [SD] age, 34 [7] years) on global disability, neurobehavioral impairment, and psychiatric symptoms, whereas cognitive changes were unremarkable. Acute predictors of 5-year outcome consistently identified TBI diagnosis with contribution from acute concussion and mental health symptoms and select measures of cognitive performance depending on the model for 5-year global disability (area under the curve following bootstrap validation [AUCBV] = 0.79), neurobehavioral impairment (correlation following bootstrap validation [RBV] = 0.60), PTSD severity (RBV = 0.36), or cognitive performance (RBV = 0.34).
Conclusions and Relevance: Service members with concussive blast injuries fared poorly at 5-year outcome. The results support a more focused acute screening of mental health following TBI diagnosis as strong indicators of poor long-term outcome. This extends prior work examining outcome in patients with concussive blast injury to the larger nonmedically evacuated population
Coordinate-Space Hartree-Fock-Bogoliubov Solvers for Superfluid Fermi Systems in Large Boxes
The self-consistent Hartree-Fock-Bogoliubov problem in large boxes can be
solved accurately in the coordinate space with the recently developed solvers
HFB-AX (2D) and MADNESS-HFB (3D). This is essential for the description of
superfluid Fermi systems with complicated topologies and significant spatial
extend, such as fissioning nuclei, weakly-bound nuclei, nuclear matter in the
neutron star rust, and ultracold Fermi atoms in elongated traps. The HFB-AX
solver based on B-spline techniques uses a hybrid MPI and OpenMP programming
model for parallel computation for distributed parallel computation, within a
node multi-threaded LAPACK and BLAS libraries are used to further enable
parallel calculations of large eigensystems. The MADNESS-HFB solver uses a
novel multi-resolution analysis based adaptive pseudo-spectral techniques to
enable fully parallel 3D calculations of very large systems. In this work we
present benchmark results for HFB-AX and MADNESS-HFB on ultracold trapped
fermions.Comment: Conference on Computational Physics (CCP 2011) Proceedin
The role of occupied d states in the relaxation of hot electrons in Au
We present first-principles calculations of electron-electron scattering
rates of low-energy electrons in Au. Our full band-structure calculations
indicate that a major contribution from occupied d states participating in the
screening of electron-electron interactions yields lifetimes of electrons in Au
with energies of above the Fermi level that are larger than
those of electrons in a free-electron gas by a factor of . This
prediction is in agreement with a recent experimental study of ultrafast
electron dynamics in Au(111) films (J. Cao {\it et al}, Phys. Rev. B {\bf 58},
10948 (1998)), where electron transport has been shown to play a minor role in
the measured lifetimes of hot electrons in this material.Comment: 4 pages, 2 figures, to appear in Phys. Rev.
Environmental and Farm Management Factors Associated with Tuberculosis on Cattle Farms in Northeastern Michigan
Objective—To identify major environmental and farm management factors associated with the occurrence of tuberculosis (TB) on cattle farms in northeastern Michigan. Design—Case-control study. Sample Population—17 cattle farms with infected cattle and 51 control farms. Procedure—Each case farm (laboratory confirmed diagnosis of Mycobacterium bovis infection) was matched with 2 to 4 control farms (negative whole-herd test results within previous 12 months) on the basis of type of farm (dairy or beef) and location. Cattle farm data were collected from in-person interviews and mailed questionnaires. Wildlife TB data were gathered through state wildlife surveillance. Environmental data were gathered from a satellite image-based geographic information system. Multivariable conditional logistic regression for matched analysis was performed. Results—Major factors associated with increased farm risk of TB were higher TB prevalence among wild deer and cattle farms in the area, herd size, and ponds or creeks in cattle housing areas. Factors associated with reduced farm risk of TB were greater amounts of natural open lands in the surrounding area and reducing deer access to cattle housing areas by housing cattle in barns, barnyards, or feedlots and use of electrified wire or barbed wire for livestock fencing. Conclusions and Clinical Relevance—Results suggest that certain environmental and management factors may be associated with risk of TB on cattle farms
On the kinks and dynamical phase transitions of alpha-helix protein chains
Heuristic insights into a physical picture of Davydov's solitonic model of
the one-dimensional protein chain are presented supporting the idea of a
non-equilibrium competition between the Davydov phase and a complementary,
dynamical- `ferroelectric' phase along the chainComment: small latex file with possible glue problems, just go on !, no
figures, small corrections with respect to the published text, follow-up work
to cond-mat/9304034 [PRE 47 (June 1993) R3818
Nonequilibrium Electron Interactions in Metal Films
Ultrafast relaxation dynamics of an athermal electron distribution is
investigated in silver films using a femtosecond pump-probe technique with 18
fs pulses in off-resonant conditions. The results yield evidence for an
increase with time of the electron-gas energy loss rate to the lattice and of
the free electron damping during the early stages of the electron-gas
thermalization. These effects are attributed to transient alterations of the
electron average scattering processes due to the athermal nature of the
electron gas, in agreement with numerical simulations
Size-Dependent Surface Plasmon Dynamics in Metal Nanoparticles
We study the effect of Coulomb correlations on the ultrafast optical dynamics
of small metal particles. We demonstrate that a surface-induced dynamical
screening of the electron-electron interactions leads to quasiparticle
scattering with collective surface excitations. In noble-metal nanoparticles,
it results in an interband resonant scattering of d-holes with surface
plasmons. We show that this size-dependent many-body effect manifests itself in
the differential absorption dynamics for frequencies close to the surface
plasmon resonance. In particular, our self-consistent calculations reveal a
strong frequency dependence of the relaxation, in agreement with recent
femtosecond pump-probe experiments.Comment: 8 pages + 4 figures, final version accepted to PR
Nonequilibrium Magnetization Dynamics of Nickel
Ultrafast magnetization dynamics of nickel has been studied for different
degrees of electronic excitation, using pump-probe second-harmonic generation
with 150 fs/800 nm laser pulses of various fluences. Information about the
electronic and magnetic response to laser irradiation is obtained from sums and
differences of the SHG intensity for opposite magnetization directions. The
classical M(T)-curve can be reproduced for delay times larger than the electron
thermalization time of about 280 fs, even when electrons and lattice have not
reached thermal equilibrium. Further we show that the transient magnetization
reaches its minimum approx. 50 fs before electron thermalization is completed.Comment: 8 pages, 5 figures, revte
- …