1,452 research outputs found
Circulating Biologically Active Adrenomedullin Predicts Organ Failure and Mortality in Sepsis
BACKGROUND: Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. Biologically active adrenomedullin (bio-ADM) is an emerging biomarker for sepsis. We explored whether bio-ADM concentration could predict severity, organ failure, and 30-day mortality in septic patients. METHODS: In 215 septic patients (109 patients with sepsis; 106 patients with septic shock), bio-ADM concentration was measured at diagnosis of sepsis, using sphingotest bio-ADM (Sphingotec GmbH, Hennigsdorf, Germany) and analyzed in terms of sepsis severity, vasopressor use, and 30-day mortality. The number of organ failures, sequential (sepsis-related) organ failure assessment (SOFA) score, and 30-day mortality were compared according to bio-ADM quartiles. RESULTS: Bio-ADM concentration was significantly higher in patients with septic shock, vasopressor use, and non-survivors than in patients with solitary sepsis, no vasopressor use, and survivors, respectively (all P<0.0001). Bio-ADM quartiles were associated with the number of organ failures (P<0.0001), as well as SOFA cardiovascular, renal, coagulation, and liver subscores (all P<0.05). The 30-day mortality rate showed a stepwise increase in each bio-ADM quartile (all P<0.0001). Bio-ADM concentration and SOFA score equally predicted the 30-day mortality (area under the curve: 0.827 vs 0.830). CONCLUSIONS: Bio-ADM could serve as a useful and objective biomarker to predict severity, organ failure, and 30-day mortality in septic patients
EPR, ENDOR, and TRIPLE resonance studies of modified bacteriochlorophyll cation radicals
A series of substituted bacteriochlorophyll molecules, all used in reconstitution experiments of reaction centers of Rhodobacter sphaeroides (Struck et al. Biochim. Biophys. Acta 1991, 1060, 262-270), were characterized by EPR, electron-nuclear double (ENDOR), and electron-nuclear-nuclear triple (TRIPLE) resonance spectroscopy in their monomeric radical cation states. Effects of different substituents at position 3 in the porphyrin macrocycle were considered, especially for two «crosslinks» between plant and bacterial chlorophylls. These are 3-vinylbacteriochlorophyll where the «bacteria» acetyl group at position 3 was substituted by vinyl and 3-acetylchlorophyll where the «plant» vinyl group was substituted by acety
Plasma adrenomedullin is associated with short-term mortality and vasopressor requirement in patients admitted with sepsis
Introduction: The incidence of death among patients admitted for severe sepsis or septic shock is high. Adrenomedullin (ADM) plays a central role in initiating the hyperdynamic response during the early stages of sepsis. Pilot studies indicate an association of plasma ADM with the severity of the disease. In the present study we utilized a novel sandwich immunoassay of bioactive plasma ADM in patients hospitalized with sepsis in order to assess the clinical utility.Methods: We enrolled 101 consecutive patients admitted to the emergency department with suspected sepsis in this study. Sepsis was defined by fulfillment of at least two systemic inflammatory response syndrome (SIRS) criteria plus clinical suspicion of infection. Plasma samples for ADM measurement were obtained on admission and for the next four days. The 28-day mortality rate was recorded.Results: ADM at admission was associated with severity of disease (correlation with Acute Physiology and Chronic Health Evaluation II (APACHE II) score: r = 0.46; P <0.0001). ADM was also associated with 28-day mortality (ADM median (IQR): survivors: 50 (31 to 77) pg/mL; non-survivors: 84 (48 to 232) pg/mL; P <0.001) and was independent from and additive to APACHE II (P = 0.02). Cox regression analysis revealed an additive value of serial measurement of ADM over baseline assessment for prediction of 28-day mortality (P < 0.01). ADM was negatively correlated with mean arterial pressure (r = -0.39; P <0.0001), and it strongly discriminated those patients requiring vasopressor therapy from the others (ADM median (IQR): no vasopressors 48 (32 to 75) pg/mL; with vasopressors 129 (83 to 264) pg/mL, P <0.0001).Conclusions: In patients admitted with sepsis, severe sepsis or septic shock plasma ADM is strongly associated with severity of disease, vasopressor requirement and 28-day mortality
The Peierls substitution in an engineered lattice potential
Artificial gauge fields open new possibilities to realize quantum many-body
systems with ultracold atoms, by engineering Hamiltonians usually associated
with electronic systems. In the presence of a periodic potential, artificial
gauge fields may bring ultracold atoms closer to the quantum Hall regime. Here,
we describe a one-dimensional lattice derived purely from effective
Zeeman-shifts resulting from a combination of Raman coupling and radiofrequency
magnetic fields. In this lattice, the tunneling matrix element is generally
complex. We control both the amplitude and the phase of this tunneling
parameter, experimentally realizing the Peierls substitution for ultracold
neutral atoms.Comment: 6 pages, 5 figure
Spectral diffusion and 14N quadrupole splittings in absorption detected magnetic resonance hole burning spectra of photosynthetic reaction centers
Zero field absorption detected magnetic resonance hole burning measurements were performed on photosynthetic reaction centers of the bacteria Rhodobacter sphaeroides R26 and Rhodopseudomonas viridis. Extrapolation to zero microwave power yielded pseudohomogeneous linewidths of 2.0 MHz for Rhodopseudomonas viridis, 1.0 and 0.9 MHz for the protonated forms of Rhodobacter sphaeroides R26 with and without monomer bacteriochlorophyll exchanged, and 0.25 MHz as an upper limit for fully deuterated reaction centers of Rhodobacter sphaeroides R26. The measured linewidths were interpreted as being due to unresolved hyperfine interaction between the nuclear spins and the triplet electron spin, the line shape being determined by spectral diffusion among the nuclei. The difference in linewidths between Rhodobacter sphaeroides R26 and Rhodopseudomonas viridis is then explained by triplet delocalization on the special pair in the former, and localization on one dimer half on the latter. In the fully deuterated sample, four quadrupole satellites were observed in the hole spectra arising from the eight 14N nitrogens in the special pair. The quadrupole parameters seem to be very similar for all nitrogens and were determined to =1.25±0.1 MHz and =0.9±0.1 MHz. The Journal of Chemical Physics is copyrighted by The American Institute of Physics
Simple Models for Turbulent Self-Regulation in Galaxy Disks
We propose that turbulent heating, wave pressure and gas exchanges between
different regions of disks play a dominant role in determining the preferred,
quasi-equilibrium, self-similar states of gas disks on large-scales. We present
simple families of analytic, thermohydrodynamic models for these global states,
which include terms for turbulent pressure and Reynolds stresses. Star
formation rates, phase balances, and hydrodynamic forces are all tightly
coupled and balanced. The models have stratified radial flows, with the cold
gas slowly flowing inward in the midplane of the disk, and with the warm/hot
phases that surround the midplane flowing outward.
The models suggest a number of results that are in accord with observation,
as well as some novel predictions, including the following. 1) The large-scale
gas density and thermal phase distributions in galaxy disks can be explained as
the result of turbulent heating and spatial couplings. 2) The turbulent
pressures and stresses that drive radial outflows in the warm gas also allow a
reduced circular velocity there. This effect was observed by Swaters, Sancisi
and van der Hulst in NGC 891, a particularly turbulent edge-on disk. The models
predict that the effect should be universal in such disks. 3) They suggest that
a star formation rate like the phenomenological Schmidt Law is the natural
result of global thermohydrodynamical balance, and may not obtain in disks far
from equilibrium. (Abridged)Comment: 37 pages, 1 gif figure, accepted for publication in the Astrophysical
Journa
Tunable gauge potential for neutral and spinless particles in driven lattices
We present a universal method to create a tunable, artificial vector gauge
potential for neutral particles trapped in an optical lattice. The necessary
Peierls phase of the hopping parameters between neighboring lattice sites is
generated by applying a suitable periodic inertial force such that the method
does not rely on any internal structure of the particles. We experimentally
demonstrate the realization of such artificial potentials, which generate
ground state superfluids at arbitrary non-zero quasi-momentum. We furthermore
investigate possible implementations of this scheme to create tuneable magnetic
fluxes, going towards model systems for strong-field physics
A Warp in Progress : H I and Radio Continuum Observations of the Spiral NGC 3145
Date of Acceptance: 16/06/2015We present VLA H I and 6 cm radio continuum observations of the spiral NGC 3145 and H I observations of its two companions, NGC 3143 and PGC 029578. In optical images NGC 3145 has stellar arms that appear to cross, forming "X"-features. Our radio continuum observations rule out shock fronts at 3 of the 4 "X"-features. In the middle-to-outer disk, the H I line-profiles of NGC 3145 are skewed. Relative to the disk, the gas in the skewed wing of the line-profiles has z-motions away from us on the approaching side of the galaxy and z-motions of about the same magnitude (about 40 km/s) towards us on the receding side. These warping motions imply that there has been a perturbation with a sizeable component perpendicular to the disk over large spatial scales. Two features in NGC 3145 have velocities indicating that they are out-of-plane tidal arms. One is an apparent branch of a main spiral arm; the velocity of the branch is 150 km/s greater than the spiral arm where they appear to intersect in projection. The other is an arm that forms 3 of the "X"-features. It differs in velocity by 56 km/s from the disk at the same projected location. Based on its SFR and H I properties, NGC 3143 is the more likely of the two companions to have interacted with NGC 3145 recently. A simple analytic model demonstrates that an encounter between NGC 3143 and NGC 3145 is a plausible explanation for the observed warping motions in NGC 3145.Peer reviewe
Large-scale Star Formation Triggering in the Low-mass Arp 82 System: A Nearby Example of Galaxy Downsizing Based on UV/Optical/Mid-IR Imaging
As part of our Spitzer Spirals, Bridges, and Tails project to help understand
the effects of galaxy interactions on star formation, we analyze GALEX
ultraviolet, SARA optical, and Spitzer infrared images of the interacting
galaxy pair Arp 82 (NGC 2535/6) and compare to a numerical simulation of the
interaction. We investigate the multiwavelength properties of several
individual star forming complexes (clumps). Using optical and UV colors,
EW(Halpha), and population synthesis models we constrain the ages of the clumps
and find that the median clump age is about 12 Myr. The clumps have masses
ranging from a few times 10^6 to 10^9 solar masses. In general, the clumps in
the tidal features have similar ages to those in the spiral region, but are
less massive. The 8 micron and 24 micron luminosities are used to estimate the
far-infrared luminosities and the star formation rates of the clumps. The total
clump star formation rate is 2.0+/-0.8 solar masses per year, while the entire
Arp 82 system is forming stars at a rate of 4.9+/-2.0 solar masses per year. We
find, for the first time, stars in the HI arc to the southeast of the NGC 2535
disk. Population synthesis models indicate that all of the observed populations
have young to intermediate ages. We conclude that although the gas disks and
some old stars may have formed early-on, the progenitors are late-type or low
surface brightness and the evolution of these galaxies was halted until the
recent encounter.Comment: Accepted for publication in the AJ, 22 Figures, 5 Table
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