90 research outputs found
Asymptotic solvers for ordinary differential equations with multiple frequencies
We construct asymptotic expansions for ordinary differential equations with highly oscillatory forcing terms, focusing on the case of multiple, non-commensurate frequencies. We derive an asymptotic expansion in inverse powers of the oscillatory parameter and use its truncation as an exceedingly effective means to discretize the differential equation in question. Numerical examples illustrate the effectiveness of the method
Structure of the mirror nuclei Be and B in a microscopic cluster model
The structure of the mirror nuclei Be and B is studied in a
microscopic and three-cluster model
using a fully antisymmetrized 9-nucleon wave function. The two-nucleon
interaction includes central and spin-orbit components and the Coulomb
potential. The ground state of Be is obtained accurately with the
stochastic variational method, while several particle-unbound states of both
Be and B are investigated with the complex scaling method.The
calculation for Be supports the recent identification for the existence of
two broad states around 6.5 MeV, and predicts the and
states at about 4.5 MeV and 8 MeV, respectively. The
similarity of the calculated spectra of Be and B enables one to
identify unknown spins and parities of the B states. Available data on
electromagnetic moments and elastic electron scatterings are reproduced very
well. The enhancement of the 1 transition of the first excited state in
Be is well accounted for. The calculated density of Be is found to
reproduce the reaction cross section on a Carbon target. The analysis of the
beta decay of Li to Be clearly shows that the wave function of Be
must contain a small component that cannot be described by the simple model. This small component can be well accounted for by extending a
configuration space to include the distortion of the -particle to
and partitions.Comment: 24 page
Patientsâ evaluations of patient safety in English general practices: a cross-sectional study
Background: The frequency and nature of safety problems and harm in general practices has previously relied on information supplied by health professionals, and scarce attention has been paid to experiences of patients.
Aim: To examine patient-reported experiences and outcomes of patient safety in Primary Care in England.
Design and Setting: Cross-sectional study in 45 general practices.
Method: A postal version of the Patient Reported Experiences and Outcomes of Safety in Primary Care (PREOS-PC) questionnaire was sent to a random sample of 6,736 patients. Main outcome measures included âpractice activationâ (what does the practice do to create a safe environment); âpatient activationâ (how pro-active are patients in ensuring safe healthcare delivery); âexperiences of safety eventsâ (safety errors); âoutcomes of safetyâ (harm); and âoverall perception of safetyâ (how safe do patients rate their practice).
Results: 1,244 patients (18.4%) returned completed questionnaires. Scores were high for âpractice activationâ (mean (standard error) = 80.4 out of 100 (2.0)) and low for âpatient activationâ (26.3 out of 100 (2.6)). A substantial proportion of patients (45%) reported having experienced at least one safety problem in the previous 12 months, mostly related to appointments (33%), diagnosis (17%), patient-provider communication (15%), and coordination between providers (14%). 221 patients (23%) reported some degree of harm in the previous 12 months. The overall assessment of the level of safety of their practices was generally high (86.0 out of 100 (16.8)).
Conclusion: Priority areas for patient safety improvement in general practices in England include appointments, diagnosis, communication, coordination and patient activation
Attachment and Entry of Chlamydia Have Distinct Requirements for Host Protein Disulfide Isomerase
Chlamydia is an obligate intracellular pathogen that causes a wide range of diseases in humans. Attachment and entry are key processes in infectivity and subsequent pathogenesis of Chlamydia, yet the mechanisms governing these interactions are unknown. It was recently shown that a cell line, CHO6, that is resistant to attachment, and thus infectivity, of multiple Chlamydia species has a defect in protein disulfide isomerase (PDI) Nâterminal signal sequence processing. Ectopic expression of PDI in CHO6 cells led to restoration of Chlamydia attachment and infectivity; however, the mechanism leading to this recovery was not ascertained. To advance our understanding of the role of PDI in Chlamydia infection, we used RNA interference to establish that cellular PDI is essential for bacterial attachment to cells, making PDI the only host protein identified as necessary for attachment of multiple species of Chlamydia. Genetic complementation and PDI-specific inhibitors were used to determine that cell surface PDI enzymatic activity is required for bacterial entry into cells, but enzymatic function was not required for bacterial attachment. We further determined that it is a PDI-mediated reduction at the cell surface that triggers bacterial uptake. While PDI is necessary for Chlamydia attachment to cells, the bacteria do not appear to utilize plasma membraneâassociated PDI as a receptor, suggesting that Chlamydia binds a cell surface protein that requires structural association with PDI. Our findings demonstrate that PDI has two essential and independent roles in the process of chlamydial infectivity: it is structurally required for chlamydial attachment, and the thiol-mediated oxido-reductive function of PDI is necessary for entry
Visceral and subcutaneous fat have different origins and evidence supports a mesothelial source
International audience: Fuelled by the obesity epidemic, there is considerable interest in the developmental origins of white adipose tissue (WAT) and the stem and progenitor cells from which it arises. Whereas increased visceral fat mass is associated with metabolic dysfunction, increased subcutaneous WAT is protective. There are six visceral fat depots: perirenal, gonadal, epicardial, retroperitoneal, omental and mesenteric, and it is a subject of much debate whether these have a common developmental origin and whether this differs from that for subcutaneous WAT. Here we show that all six visceral WAT depots receive a significant contribution from cells expressing Wt1 late in gestation. Conversely, no subcutaneous WAT or brown adipose tissue arises from Wt1-expressing cells. Postnatally, a subset of visceral WAT continues to arise from Wt1-expressing cells, consistent with the finding that Wt1 marks a proportion of cell populations enriched in WAT progenitors. We show that all visceral fat depots have a mesothelial layer like the visceral organs with which they are associated, and provide several lines of evidence that Wt1-expressing mesothelium can produce adipocytes. These results reveal a major ontogenetic difference between visceral and subcutaneous WAT, and pinpoint the lateral plate mesoderm as a major source of visceral WAT. They also support the notion that visceral WAT progenitors are heterogeneous, and suggest that mesothelium is a source of adipocytes
Linear domain interactome and biological function of anterior gradient 2
The Anterior Gradient 2 (AGR2) protein has been implicated in a variety
of biological systems linked to cancer and metastasis, tamoxifen-induced drug
resistance, pro-inflammatory diseases like IBD and asthma, and limb regeneration.
The molecular mechanisms by which AGR2 mediates these various
phenotypes in disease progression in both cancer and IBD are poorly understood,
as is the biological function(s) of AGR2 under non-disease conditions.
Here, we use a combination of biochemical techniques, organ culture, cell biology
and mouse genetics to investigate the biological significance of AGR2
both in cell lines and in vivo. We present data based on phage-peptide inter-actomics
screens suggesting a role for AGR2 in mediating the maturation and
trafficking of a class of membrane and secretory proteins, and investigate a putative
interaction between AGR2 and one member of this class of proteins. We
also describe the construction of a universal vector for use in making a variety
of transgenic animals, and then present data showing its use as a promoter
reporter, and attempt to investigate the temporal and spatial expression of
AGR2 in the developing and adult mouse. Further, we present data describing
the localisation pattern of AGR2 in the developing murine kidney using
a combination of organ culture and antibody staining, and suggest a role for
AGR2 in the developing kidney based on this data that is in agreement with
a chaperone function for membrane and secretory proteins. Together, these
data suggest that AGR2 has an intrinsic consensus docking site for a subset
of its client proteins, that AGR2 plays a role in protein maturation in ciliated
cell types, and provides a novel biological model to dissect the role of AGR2
in ER-trafficking
Optical control of a resonant tunneling diode microwave-photonic oscillator
We report on optical injection-locking of a microwave-photonic oscillator based on the integration of a resonant tunneling diode optical waveguide photodetector with a communication laser diode. The oscillator locking was achieved with in-fiber optical powers as low as 0.2 mW, and locking ranges up to 23.8 MHz for in-fiber optical power of few milliwatts and with phase-noise suppression below -110 dBc/Hz at 10-kHz frequency offset from the center frequency. The circuit's dynamics are well described as an optically controlled LieÌnard oscillator
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