48 research outputs found
Nematic Ordering of Rigid Rods in a Gravitational Field
The isotropic-to-nematic transition in an athermal solution of long rigid
rods subject to a gravitational (or centrifugal) field is theoretically
considered in the Onsager approximation. The new feature emerging in the
presence of gravity is a concentration gradient which coupled with the nematic
ordering. For rodlike molecules this effect becomes noticeable at centrifugal
acceleration g ~ 10^3--10^4 m/s^2, while for biological rodlike objects, such
as tobacco mosaic virus, TMV, the effect is important even for normal
gravitational acceleration conditions. Rods are concentrated near the bottom of
the vessel which sometimes leads to gravity induced nematic ordering. The
concentration range corresponding to phase separation increases with increasing
g. In the region of phase separation the local rod concentration, as well as
the order parameter, follow a step function with height.Comment: Full article http://prola.aps.org/abstract/PRE/v60/i3/p2973_
Long-range potential fluctuations and 1/f noise in hydrogenated amorphous silicon
We present a microscopic theory of the low-frequency voltage noise (known as
"1/f" noise) in micrometer-thick films of hydrogenated amorphous silicon. This
theory traces the noise back to the long-range fluctuations of the Coulomb
potential produced by deep defects, thereby predicting the absolute noise
intensity as a function of the distribution of defect activation energies. The
predictions of this theory are in very good agreement with our own experiments
in terms of both the absolute intensity and the temperature dependence of the
noise spectra.Comment: 8 pages, 3 figures, several new parts and one new figure are added,
but no conceptual revision
F901318 represents a novel class of antifungal drug that inhibits dihydroorotate dehydrogenase
There is an important medical need for new antifungal agents with novel mechanisms of action to treat the increasing number of patients with life-threatening systemic fungal disease and to overcome the growing problem of resistance to current therapies. F901318, the leading representative of a novel class of drug, the orotomides, is an antifungal drug in clinical development that demonstrates excellent potency against a broad range of dimorphic and filamentous fungi. In vitro susceptibility testing of F901318 against more than 100 strains from the four main pathogenic Aspergillus spp. revealed minimal inhibitory concentrations of â€0.06 ”g/mLâgreater potency than the leading antifungal classes. An investigation into the mechanism of action of F901318 found that it acts via inhibition of the pyrimidine biosynthesis enzyme dihydroorotate dehydrogenase (DHODH) in a fungal-specific manner. Homology modeling of Aspergillus fumigatus DHODH has identified a predicted binding mode of the inhibitor and important interacting amino acid residues. In a murine pulmonary model of aspergillosis, F901318 displays in vivo efficacy against a strain of A. fumigatus sensitive to the azole class of antifungals and a strain displaying an azole-resistant phenotype. F901318 is currently in late Phase 1 clinical trials, offering hope that the antifungal armamentarium can be expanded to include a class of agent with a mechanism of action distinct from currently marketed antifungals
Embodied Knowledge: Writing Researchersâ Bodies Into Qualitative Health Research
After more than a decade of postpositivist health care research and an increase in narrative writing practices, social scientific, qualitative health research remains largely disembodied. The erasure of researchersâ bodies from conventional accounts of research obscures the complexities of knowledge production and yields deceptively tidy accounts of research. Qualitative health research could benefit significantly from embodied writing that explores the discursive relationship between the body and the self and the semantic challenges of writing the body by incorporating bodily details and experiences into research accounts. Researchers can represent their bodies by incorporating autoethnographic narratives, drawing on all of their senses, interrogating the connections between their bodily signifiers and research processes, and experimenting with the semantics of self and body. The author illustrates opportunities for embodiment with excerpts from an ethnography of a geriatric oncology team and explores implications of embodied writing for the practice of qualitative health research
ESC Working Group Cellular Biology of the Heart: Position Paper: Improving the pre-clinical assessment of novel cardioprotective therapies
Ischemic heart disease (IHD) remains the leading cause of death and disability worldwide. As a result, novel therapies are still needed to protect the heart from the detrimental effects of acute ischemia-reperfusion injury, in order to improve clinical outcomes in IHD patients. In this regard, although a large number of novel cardioprotective therapies discovered in the research laboratory have been investigated in the clinical setting, only a few of these have been demonstrated to improve clinical outcomes. One potential reason for this lack of success may have been the failure to thoroughly assess the cardioprotective efficacy of these novel therapies in suitably designed pre-clinical experimental animal models. Therefore, the aim of this Position Paper by the European Society of Cardiology Working Group Cellular Biology of the Heart is to provide recommendations for improving the pre-clinical assessment of novel cardioprotective therapies discovered in the research laboratory, with the aim of increasing the likelihood of success in translating these new treatments into improved clinical outcomes
Nomenclature and listing of celiac disease relevant gluten T-cell epitopes restricted by HLA-DQ molecules
Celiac disease is caused by an abnormal intestinal T-cell response to gluten proteins of wheat, barley and rye. Over the last few years, a number of gluten T-cell epitopes restricted by celiac disease associated HLA-DQ molecules have been characterized. In this work, we give an overview of these epitopes and suggest a comprehensive, new nomenclature
Reconstruction of major maternal and paternal lineages of the Cape Muslim population
The earliest Cape Muslims were brought to the Cape (Cape Town - South Africa) from Africa and Asia from 1652 to
1834. They were part of an involuntary migration of slaves, political prisoners and convicts, and they contributed to
the ethnic diversity of the present Cape Muslim population of South Africa. The history of the Cape Muslims has been
well documented and researched however no in-depth genetic studies have been undertaken. The aim of the present
study was to determine the respective African, Asian and European contributions to the mtDNA (maternal) and
Y-chromosomal (paternal) gene pool of the Cape Muslim population, by analyzing DNA samples of 100 unrelated
Muslim males born in the Cape Metropolitan area. A panel of six mtDNA and eight Y-chromosome SNP markers
were screened using polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLP). Overall
admixture estimates for the maternal line indicated Asian (0.4168) and African mtDNA (0.4005) as the main contributors.
The admixture estimates for the paternal line, however, showed a predominance of the Asian contribution
(0.7852). The findings are in accordance with historical data on the origins of the early Cape Muslims.Web of Scienc
Multi-messenger Observations of a Binary Neutron Star Merger
On 2017 August 17 a binary neutron star coalescence candidate (later
designated GW170817) with merger time 12:41:04 UTC was observed through
gravitational waves by the Advanced LIGO and Advanced Virgo detectors.
The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray
burst (GRB 170817A) with a time delay of ⌠1.7 {{s}} with respect to
the merger time. From the gravitational-wave signal, the source was
initially localized to a sky region of 31 deg2 at a
luminosity distance of {40}-8+8 Mpc and with
component masses consistent with neutron stars. The component masses
were later measured to be in the range 0.86 to 2.26 {M}ÈŻ
. An extensive observing campaign was launched across the
electromagnetic spectrum leading to the discovery of a bright optical
transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC
4993 (at ⌠40 {{Mpc}}) less than 11 hours after the merger by the
One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The
optical transient was independently detected by multiple teams within an
hour. Subsequent observations targeted the object and its environment.
Early ultraviolet observations revealed a blue transient that faded
within 48 hours. Optical and infrared observations showed a redward
evolution over âŒ10 days. Following early non-detections, X-ray and
radio emission were discovered at the transientâs position ⌠9
and ⌠16 days, respectively, after the merger. Both the X-ray and
radio emission likely arise from a physical process that is distinct
from the one that generates the UV/optical/near-infrared emission. No
ultra-high-energy gamma-rays and no neutrino candidates consistent with
the source were found in follow-up searches. These observations support
the hypothesis that GW170817 was produced by the merger of two neutron
stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and
a kilonova/macronova powered by the radioactive decay of r-process
nuclei synthesized in the ejecta.</p