3,936 research outputs found
Measuring cosmological bulk flows via the kinematic Sunyaev-Zeldovich effect in the upcoming cosmic microwave background maps
We propose a new method to measure the possible large-scale bulk flows in the
Universe from the cosmic microwave background (CMB) maps from the upcoming
missions, MAP and Planck. This can be done by studying the statistical
properties of the CMB temperature field at many X-ray cluster positions. At
each cluster position, the CMB temperature fluctuation will be a combination of
the Sunyaev-Zeldovich (SZ) kinematic and thermal components, the cosmological
fluctuations and the instrument noise term. When averaged over many such
clusters the last three will integrate down, whereas the first one will be
dominated by a possible bulk flow component. In particular, we propose to use
all-sky X-ray cluster catalogs that should (or could) be available soon from
X-ray satellites, and then to evaluate the dipole component of the CMB field at
the cluster positions. We show that for the MAP and Planck mission parameters
the dominant contributions to the dipole will be from the terms due to the SZ
kinematic effect produced by the bulk flow (the signal we seek) and the
instrument noise (the noise in our signal). Computing then the expected
signal-to-noise ratio for such measurement, we get that at the 95 % confidence
level the bulk flows on scales >100h^{-1} Mpc can be probed down to the
amplitude of km/sec with the MAP data and down to only 30 km/sec with
the Planck mission.Comment: Astrophysical Journal Letters, in pres
Load fluctuations drive actin network growth
The growth of actin filament networks is a fundamental biological process
that drives a variety of cellular and intracellular motions. During motility,
eukaryotic cells and intracellular pathogens are propelled by actin networks
organized by nucleation-promoting factors, which trigger the formation of
nascent filaments off the side of existing filaments in the network. A Brownian
ratchet (BR) mechanism has been proposed to couple actin polymerization to
cellular movements, whereby thermal motions are rectified by the addition of
actin monomers at the end of growing filaments. Here, by following
actin--propelled microspheres using three--dimensional laser tracking, we find
that beads adhered to the growing network move via an object--fluctuating BR.
Velocity varies with the amplitude of thermal fluctuation and inversely with
viscosity as predicted for a BR. In addition, motion is saltatory with a broad
distribution of step sizes that is correlated in time. These data point to a
model in which thermal fluctuations of the microsphere or entire actin network,
and not individual filaments, govern motility. This conclusion is supported by
Monte Carlo simulations of an adhesion--based BR and suggests an important role
for membrane tension in the control of actin--based cellular protrusions.Comment: To be published in PNA
P02.63. Efficacy of an 8-week online mindfulness stress management program in a corporate call center
Electron spin resonance of nitrogen-vacancy centers in optically trapped nanodiamonds
Using an optical tweezers apparatus, we demonstrate three-dimensional control
of nanodiamonds in solution with simultaneous readout of ground-state
electron-spin resonance (ESR) transitions in an ensemble of diamond
nitrogen-vacancy (NV) color centers. Despite the motion and random orientation
of NV centers suspended in the optical trap, we observe distinct peaks in the
measured ESR spectra qualitatively similar to the same measurement in bulk.
Accounting for the random dynamics, we model the ESR spectra observed in an
externally applied magnetic field to enable d.c. magnetometry in solution. We
estimate the d.c. magnetic field sensitivity based on variations in ESR line
shapes to be ~50 microTesla/Hz^1/2. This technique may provide a pathway for
spin-based magnetic, electric, and thermal sensing in fluidic environments and
biophysical systems inaccessible to existing scanning probe techniques.Comment: 29 pages, 13 figures for manuscript and supporting informatio
Comorbidity between ADHD and symptoms of bipolar disorder in a community sample of children and adolescents
Mixed-state twin observables
Twin observables, i.e. opposite subsystem observables A+ and A- that are
indistinguishable in measurement in a given mixed or pure state W, are
investigated in detail algebraicly and geometrically. It is shown that there is
a far-reaching correspondence between the detectable (in W) spectral entities
of the two operators. Twin observables are state-dependently quantum-logically
equivalent, and direct subsystem measurement of one of them ipso facto gives
rise to the indirect (i.e. distant) measurement of the other. Existence of
nontrivial twins requires singularity of W. Systems in thermodynamic
equilibrium do not admit subsystem twins. These observables may enable one to
simplify the matrix representing W.Comment: 13 page
To stress or not to stress: Physiological responses to tetrodotoxin in resistant gartersnakes vary by sex
The activation of the hypothalamic pituitary adrenal (HPA) axis is one of the most important physiological processes in coping with any deviation in an organism’s homeostasis. This activation and the secretion of glucocorticoids, such as corticosterone, allow organisms to cope with perturbations and return to optimal physiological functioning as quickly as possible. In this study, we examined the HPA axis activation in common gartersnakes (Thamnophis sirtalis) as a response to a natural toxin, tetrodotoxin (TTX). This neurotoxin is found in high levels in the Rough-skinned Newt (Taricha granulosa), which is a prey item for these snakes. To consume this toxic prey, these snakes have evolved variable resistance. We hypothesized that the more resistant individuals would show a lower HPA axis response than less resistant individuals, as measured by corticosterone (CORT) and bactericidal ability, which is a functional downstream measurement of CORT’s activity. We determined “resistance level” for tetrodotoxin from each individual snake by determining the dose which reduced race speed by 50%. Individuals were injected them with an increasing amount of tetrodotoxin (10, 25, and 50 MAMUs) to determine this value. Thirty minutes after every injection, we gathered blood samples from each snake. Our results show that, while there were no significant differences among individual CORT levels in a dose-dependent manner, female snakes did have a larger stress response when compared to both males and juveniles. Different life-histories could explain why females were able to mount a higher HPA axis response. However, TTX had no downstream effects on bactericidal ability, although juveniles had consistently lower values than adults. Our research shows a possible dichotomy between how each sex manages tetrodotoxin and gives way for a more comprehensive analysis of tetrodotoxin in an ecological context
Survival and Functional Outcomes After Hip Fracture Among Nursing Home Residents
Importance
Little is known regarding outcomes after hip fracture among long-term nursing home residents.
Objective
To describe patterns and predictors of mortality and functional decline in activities of daily living (ADLs) among nursing home residents after hip fracture.
Design, Setting, and Participants
Retrospective cohort study of 60 111 Medicare beneficiaries residing in nursing homes who were hospitalized with hip fractures between July 1, 2005, and June 30, 2009.
Main Outcomes and Measures
Data sources included Medicare claims and the Nursing Home Minimum Data Set. Main outcomes included death from any cause at 180 days after fracture and a composite outcome of death or new total dependence in locomotion at the latest available assessment within 180 days. Additional analyses described within-residents changes in function in 7 ADLs before and after fracture.
Results
Of 60 111 patients, 21 766 (36.2%) died by 180 days after fracture; among patients not totally dependent in locomotion at baseline, 53.5% died or developed new total dependence within 180 days. Within individual patients, function declined substantially after fracture across all ADL domains assessed. In adjusted analyses, the greatest decreases in survival after fracture occurred with age older than 90 years (vs ≤75 years: hazard ratio [HR], 2.17; 95% CI, 2.09-2.26 [P \u3c .001]), nonoperative fracture management (vs internal fixation: HR for death, 2.08; 95% CI, 2.01-2.15 [P \u3c .001]), and advanced comorbidity (Charlson score of ≥5 vs 0: HR, 1.66; 95% CI, 1.58-1.73 [P \u3c .001]). The combined risk of death or new total dependence in locomotion within 180 days was greatest among patients with very severe cognitive impairment (vs intact cognition: relative risk [RR], 1.66; 95% CI, 1.56-1.77 [P \u3c .001]), patients receiving nonoperative management (vs internal fixation: RR, 1.48; 95% CI, 1.45-1.51 [P \u3c .001]), and patients older than 90 years (vs ≤75 years: RR, 1.42; 95% CI, 1.37-1.46 [P \u3c .001]).
Conclusions and Relevance
Survival and functional outcomes are poor after hip fracture among nursing home residents, particularly for patients receiving nonoperative management, the oldest old, and patients with multiple comorbidities and advanced cognitive impairment. Care planning should incorporate appropriate prognostic information related to outcomes in this population
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Oligonucleotide compound and method for treating nidovirus infections
A method and oligonucleotide compound for inhibiting replication of a nidovirus in virus-infected animal cells are disclosed. The compound (i) has a nuclease-resistant backbone, (ii) is capable of uptake by the infected cells, (iii) contains between 8-25 nucleotide bases, and (iv) has a sequence capable of disrupting base pairing between the transcriptional regulatory sequences in the 5′ leader region of the positive-strand viral genome and negative-strand 3′ subgenomic region. In practicing the method, infected cells are exposed to the compound in an amount effective to inhibit viral replication
Bromine measurements in ozone depleted air over the Arctic Ocean
In situ measurements of ozone, photochemically active bromine compounds, and other trace gases over the Arctic Ocean in April 2008 are used to examine the chemistry and geographical extent of ozone depletion in the arctic marine boundary layer (MBL). Data were obtained from the NOAA WP-3D aircraft during the Aerosol, Radiation, and Cloud Processes affecting Arctic Climate (ARCPAC) study and the NASA DC-8 aircraft during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) study. Fast (1 s) and sensitive (detection limits at the low pptv level) measurements of BrCl and BrO were obtained from three different chemical ionization mass spectrometer (CIMS) instruments, and soluble bromide was measured with a mist chamber. The CIMS instruments also detected Br2. Subsequent laboratory studies showed that HOBr rapidly converts to Br2 on the Teflon instrument inlets. This detected Br2 is identified as active bromine and represents a lower limit of the sum HOBr + Br2. The measured active bromine is shown to likely be HOBr during daytime flights in the arctic. In the MBL over the Arctic Ocean, soluble bromide and active bromine were consistently elevated and ozone was depleted. Ozone depletion and active bromine enhancement were confined to the MBL that was capped by a temperature inversion at 200–500 m altitude. In ozone-depleted air, BrO rarely exceeded 10 pptv and was always substantially lower than soluble bromide that was as high as 40 pptv. BrCl was rarely enhanced above the 2 pptv detection limit, either in the MBL, over Alaska, or in the arctic free troposphere
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