957 research outputs found
DNA cytosine hydroxymethylation levels are distinct among non-overlapping classes of peripheral blood leukocytes
AbstractBackgroundPeripheral blood leukocytes are the most commonly used surrogates to study epigenome-induced risk and epigenomic response to disease-related stress. We considered the hypothesis that the various classes of peripheral leukocytes differentially regulate the synthesis of 5-methylcytosine (5mCG) and its removal via Ten-Eleven Translocation (TET) dioxygenase catalyzed hydroxymethylation to 5-hydroxymethylcytosine (5hmCG), reflecting their responsiveness to environment. Although it is known that reductions in TET1 and/or TET2 activity lead to the over-proliferation of various leukocyte precursors in bone marrow and in development of chronic myelomonocytic leukemia and myeloproliferative neoplasms, the role of 5mCG hydroxymethylation in peripheral blood is less well studied.ResultsWe developed simplified protocols to rapidly and reiteratively isolate non-overlapping leukocyte populations from a single small sample of fresh or frozen whole blood. Among peripheral leukocyte types we found extreme variation in the levels of transcripts encoding proteins involved in cytosine methylation (DNMT1, 3A, 3B), the turnover of 5mC by demethylation (TET1, 2, 3), and DNA repair (GADD45A, B, G) and in the global and gene-region-specific levels of DNA 5hmCG (CD4+ T cells≫CD14+ monocytes>CD16+ neutrophils>CD19+ B cells>CD56+ NK cells>Siglec8+ eosinophils>CD8+ T cells).ConclusionsOur data taken together suggest a potential hierarchy of responsiveness among classes of leukocytes with CD4+, CD8+ T cells and CD14+ monocytes being the most distinctly poised for a rapid methylome response to physiological stress and disease
Influence of nearly resonant light on the scattering length in low-temperature atomic gases
We develop the idea of manipulating the scattering length in
low-temperature atomic gases by using nearly resonant light. As found, if the
incident light is close to resonance with one of the bound levels of
electronically excited molecule, then virtual radiative transitions of a pair
of interacting atoms to this level can significantly change the value and even
reverse the sign of . The decay of the gas due to photon recoil, resulting
from the scattering of light by single atoms, and due to photoassociation can
be minimized by selecting the frequency detuning and the Rabi frequency. Our
calculations show the feasibility of optical manipulations of trapped Bose
condensates through a light-induced change in the mean field interaction
between atoms, which is illustrated for Li.Comment: 12 pages, 1 Postscript figur
Near Resonant Spatial Images of Confined Bose-Einstein Condensates in the '4D' Magnetic Bottle
We present quantitative measurements of the spatial density profile of
Bose-Einstein condensates of sodium atoms confined in a new '4D' magnetic
bottle. The condensates are imaged in transmission with near resonant laser
light. We demonstrate that the Thomas-Fermi surface of a condensate can be
determined to better than 1%. More generally, we obtain excellent agreement
with mean-field theory. We conclude that precision measurements of atomic
scattering lengths and interactions between phase separated cold atoms in a
harmonic trap can be measured with high precision using this method.Comment: 15 pages, 3 figures. Submitted 10/30/97, accepted for publication in
Phys. Rev. A Rapid Com
Limiting distributions for explosive PAR(1) time series with strongly mixing innovation
This work deals with the limiting distribution of the least squares
estimators of the coefficients a r of an explosive periodic autoregressive of
order 1 (PAR(1)) time series X r = a r X r--1 +u r when the innovation {u k }
is strongly mixing. More precisely {a r } is a periodic sequence of real
numbers with period P \textgreater{} 0 and such that P r=1 |a r |
\textgreater{} 1. The time series {u r } is periodically distributed with the
same period P and satisfies the strong mixing property, so the random variables
u r can be correlated
A crossover randomised controlled trial of oral mandibular advancement devices for obstructive sleep apnoea-hypopnoea (TOMADO)
Rationale Mandibular advancement devices (MADs)
are used to treat obstructive sleep apnoea-hypopnoea
syndrome (OSAHS) but evidence is lacking regarding
their clinical and cost-effectiveness in less severe disease.
Objectives To compare clinical- and cost-effectiveness
of a range of MADs against no treatment in mild to
moderate OSAHS.
Measurements and methods This open-label,
randomised, controlled, crossover trial was undertaken at
a UK sleep centre. Adults with Apnoea-Hypopnoea Index
(AHI) 5–<30/h and Epworth Sleepiness Scale (ESS) score
≥9 underwent 6 weeks of treatment with three nonadjustable
MADs: self-moulded (SleepPro 1; SP1);
semi-bespoke (SleepPro 2; SP2); fully-bespoke MAD
(bMAD); and 4 weeks no treatment. Primary outcome
was AHI scored by a polysomnographer blinded to
treatment. Secondary outcomes included ESS, quality of
life, resource use and cost.
Main results 90 patients were randomised and 83
were analysed. All devices reduced AHI compared with
no treatment by 26% (95% CI 11% to 38%, p=0.001)
for SP1, 33% (95% CI 24% to 41%) for SP2 and 36%
(95% CI 24% to 45%, p<0.001) for bMAD. ESS was
1.51 (95% CI 0.73 to 2.29, p<0.001, SP1) to 2.37
(95% CI 1.53 to 3.22, p<0.001, bMAD) lower than no
treatment (p<0.001 for all). Compliance was lower for
SP1, which was the least preferred treatment at trial exit.
All devices were cost-effective compared with no
treatment at a £20 000/quality-adjusted life year (QALY)
threshold. SP2 was the most cost-effective up to
£39 800/QALY.
Conclusions Non-adjustable MADs achieve clinically
important improvements in mild to moderate OSAHS and
are cost-effective
A stationary source of non-classical or entangled atoms
A scheme for generating continuous beams of atoms in non-classical or
entangled quantum states is proposed and analyzed. For this the recently
suggested transfer technique of quantum states from light fields to collective
atomic excitation by Stimulated Raman adiabatic passage [M.Fleischhauer and
M.D. Lukin, Phys.Rev.Lett. 84, 5094 (2000)] is employed and extended to matter
waves
Optical Confinement of a Bose-Einstein Condensate
Bose-Einstein condensates of sodium atoms have been confined in an optical
dipole trap using a single focused infrared laser beam. This eliminates the
restrictions of magnetic traps for further studies of atom lasers and
Bose-Einstein condensates. More than five million condensed atoms were
transferred into the optical trap. Densities of up to of Bose condensed atoms were obtained, allowing for a measurement of
the three-body decay rate constant for sodium condensates as . At lower densities, the observed 1/e
lifetime was more than 10 sec. Simultaneous confinement of Bose-Einstein
condensates in several hyperfine states was demonstrated.Comment: 5 pages, 4 figure
Rotational master equation for cold laser-driven molecules
The equations of motion for the molecular rotation are derived for
vibrationally cold dimers that are polarized by off-resonant laser light. It is
shown that, by eliminating electronic and vibrational degrees of freedom, a
quantum master equation for the reduced rotational density operator can be
obtained. The coherent rotational dynamics is caused by stimulated Raman
transitions, whereas spontaneous Raman transitions lead to decoherence in the
motion of the quantized angular momentum. As an example the molecular dynamics
for the optical Kerr effect is chosen, revealing decoherence and heating of the
molecular rotation.Comment: 11 pages, 5 figures, to appear in Phys. Rev.
Facial expressions depicting compassionate and critical emotions: the development and validation of a new emotional face stimulus set
Attachment with altruistic others requires the ability to appropriately process affiliative and kind facial cues. Yet there is no stimulus set available to investigate such processes. Here, we developed a stimulus set depicting compassionate and critical facial expressions, and validated its effectiveness using well-established visual-probe methodology. In Study 1, 62 participants rated photographs of actors displaying compassionate/kind and critical faces on strength of emotion type. This produced a new stimulus set based on N = 31 actors, whose facial expressions were reliably distinguished as compassionate, critical and neutral. In Study 2, 70 participants completed a visual-probe task measuring attentional orientation to critical and compassionate/kind faces. This revealed that participants lower in self-criticism demonstrated enhanced attention to compassionate/kind faces whereas those higher in self-criticism showed no bias. To sum, the new stimulus set produced interpretable findings using visual-probe methodology and is the first to include higher order, complex positive affect displays
Linear and nonlinear optical properties of the conjugated polymers PPV and MEH-PPV
We have used absorption and electroabsorption spectroscopy to investigate the electronic structure of poly(para-phenylene vinylene) (PPV) and poly (2-methoxy, 5-(2'-(ethyl)hexyloxy)-p-phenylene vinylene) (MEH-PPV). In particular we examine the often used assumption that the electronic structure of PPV and its dialkoxy substituted derivatives are essentially the same. The absorption spectrum of PPV consists of three peaks, while that of MEH-PPV has four peaks. We discuss the controversial origin of the extra peak as well as evidence for Davydov splitting effects in the absorption spectrum of PPV. The analysis of the nonlinear spectra shows further differences between the two materials. First, the binding energy of the 1B(u) exciton for PPV is some 0.1 eV higher than for MEH-PPV. Second, the peak value of Im{chi((3))(-omega;0,0,omega)} for PPV is approximately 40 times higher than that of MEH-PPV. We also found that the sum-over-states modeling of the electroabsorption spectra indicates that the transition dipole moment between the mA(g) and nB(u) states is of opposite sign in the two polymers. [S0163-1829(99)02523-0]
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