1,988 research outputs found
Pressure Effects in Supercooled Water: Comparison between a 2D Model of Water and Experiments for Surface Water on a Protein
Experiments in bulk water confirm the existence of two local arrangements of
water molecules with different densities, but, because of inevitable freezing
at low temperature , can not ascertain whether the two arrangements separate
in two phases. To avoid the freezing, new experiments measure the dynamics of
water at low on the surface of proteins, finding a crossover from a
non-Arrhenius regime at high to a regime that is approximately Arrhenius at
low . Motivated by these experiments, Kumar et al. [Phys. Rev. Lett. 100,
105701 (2008)] investigated, by Monte Carlo simulations and mean field
calculations, the relation of the dynamic crossover with the coexistence of two
liquid phases in a cell model for water and predict that: (i) the dynamic
crossover is isochronic, i.e. the value of the crossover time is
approximately independent of pressure ; (ii) the Arrhenius activation energy
of the low- regime decreases upon increasing ; (iii) the
temperature at which reaches a fixed macroscopic time
decreases upon increasing ; in particular, this is
true also for the crossover temperature at which . Here, we compare these predictions with recent quasi elastic neutron
scattering (QENS) experiments performed by X.-Q. Chu {\it et al.} on hydrated
proteins at different values of . We find that the experiments are
consistent with these three predictions.Comment: 18 pages, 5 figures, to appear on J. Phys.: Cond. Ma
Mattia Damiani (1705–1776), poet and scientist in eighteenth century Tuscany
Mattia Damiani da Volterra (1705–1776), “renowned Doctor,” was the author
in 1754 of a collection of scientifi c poems, Le Muse Fisiche (The Physical Muses) on
two subjects: Newtonian physics and the plurality of the worlds. Damiani’s interest
in science was precocious, but even at that, it was superimposed on his studies in
jurisprudence completed in Pisa in 1726. In 2003, Damiani’s lost text, De Hygrometris
et eorum defectibus disputatio (Disputation about hygrometers and their defects),
which was printed in 1726 in Pisa, was brought to light. It characterizes him as a
young scientist who refl ected upon the properties and limits of laboratory instruments
and on nascent aspects of climatology. In this Disputation, a delightful amalgamation
of scientifi c and humanistic literature is pursued. A discussion of the properties
and limits of contemporary hygrometers and a comparison of the Cartesian and
Newtonian hypotheses about cloud formations are interspersed with quotations of
verses on natural phenomena, mostly from poems of the classic age—a prelude to
the author’s future involvement in writing scientifi c verses. The poetry of Damiani,
which often shows a musicality comparable to that of the poet Giacomo Leopardi
(1798–1837), deserves to be recognized and saved from oblivion. Especially remarkable
is the implicit “multimedia” project of a union among science, poetry, theater,
and music. The rediscovered Disputation about hygrometers opens a new window on
the personages involved and on the evolution of meteorological concepts in Europe in
the context of the then-new Galilean and Newtonian physics
Energy-resolved Photoconductivity Mapping in a Monolayer-bilayer WSe2 Lateral Heterostructure
Vertical and lateral heterostructures of van der Waals materials provide
tremendous flexibility for band structure engineering. Since electronic bands
are sensitively affected by defects, strain, and interlayer coupling, the edge
and heterojunction of these two-dimensional (2D) systems may exhibit novel
physical properties, which can be fully revealed only by spatially resolved
probes. Here, we report the spatial mapping of photoconductivity in a
monolayer-bilayer WSe2 lateral heterostructure under multiple excitation
lasers. As the photon energy increases, the light-induced conductivity detected
by microwave impedance microscopy first appears along the hetero-interface and
bilayer edge, then along the monolayer edge, inside the bilayer area, and
finally in the interior of the monolayer region. The sequential emergence of
mobile carriers in different sections of the sample is consistent with the
theoretical calculation of local energy gaps. Quantitative analysis of the
microscopy and transport data also reveals the linear dependence of
photoconductivity on the laser intensity and the influence of interlayer
coupling on carrier recombination. Combining theoretical modeling, atomic scale
imaging, mesoscale impedance microscopy, and device-level characterization, our
work suggests an exciting perspective to control the intrinsic band-gap
variation in 2D heterostructures down to the few-nanometer regime.Comment: 18 pages, 5 figures; Nano Lett., Just Accepted Manuscrip
Growth factor concentrations in platelet-rich plasma for androgenetic alopecia: an intra-subject, randomized, blinded, placebo-controlled, pilot study
YesBackground: Platelet rich plasma (PRP), processed from autologous peripheral blood, is used to
treat androgenetic alopecia (AGA). Objective: To determine the efficacy of PRP for hair growth
promotion in AGA patients in a randomized, blinded, placebo controlled, pilot clinical trial
(NCT02074943). Methods: The efficacy of an 8 week, 5 session, PRP treatment course was
determined by measuring hair density and hair caliber changes in 10 AGA affected patients. For
each PRP sample, the concentrations of selected growth factors were determined using a
multiplex assay system. The clinical results were then correlated to the growth factor
concentrations in PRP. Results: At 16 weeks, 8 weeks after the last PRP injection, treated areas
exhibited increased mean hair density (+12.76%) over baseline compared to placebo (+0.99%).
Mean hair caliber decreased in both treated and placebo regions (-16.22% and -19.46%
respectively). Serial analysis of PRP significant variability in concentrations between patients.
Overall, there was a positive correlation between GDNF concentration and hair density (p=
0.004). Trends, though not statistically significant, were also observed for FGF2 and VEGF.
Limitations: Small sample size and lack of comparative cohorts receiving protocol variations
limit confidence in the study data. Conclusions: This small pilot clinical trial suggests PRP
treatment may be beneficial for AGA. However, the variable hair growth responses between
patients indicate there is a significant opportunity to improve PRP therapy protocols for hair
growth promotion. The variability in growth factor concentration in PRP suggests
standardization of growth factors post-processing might improve hair growth responses.RepliCel Life Sciences Inc. (Canada
Systemic inflammatory response syndrome, quick sequential organ function assessment, and organ dysfunction: insights from a prospective database of ED patients with infection
Background A proposed revision of sepsis definitions has abandoned the systemic inflammatory response syndrome (SIRS), defined organ dysfunction as an increase in total Sequential Organ Function Assessment (SOFA) score of\ua0≥ 2, and conceived “qSOFA” (quick SOFA) as a bedside indicator of organ dysfunction. We aimed to (1) determine the prognostic impact of SIRS, (2) compare the diagnostic accuracy of SIRS and qSOFA for organ dysfunction, and (3) compare standard (Sepsis-2) and revised (Sepsis-3) definitions for organ dysfunction in ED patients with infection. Methods Consecutive ED patients admitted with presumed infection were prospectively enrolled over 3 years. Sufficient observational data were collected to calculate SIRS, qSOFA, SOFA, comorbidity, and mortality. Results We enrolled 8,871 patients, with SIRS present in 4,176 (47.1%). SIRS was associated with increased risk of organ dysfunction (relative risk [RR] 3.5) and mortality in patients without organ dysfunction (OR 3.2). SIRS and qSOFA showed similar discrimination for organ dysfunction (area under the receiver operating characteristic curve, 0.72 vs\ua00.73). qSOFA was specific but poorly sensitive for organ dysfunction (96.1%\ua0and 29.7%, respectively). Mortality for patients with organ dysfunction was similar for Sepsis-2 and Sepsis-3 (12.5%\ua0and 11.4%, respectively), although 29%\ua0of patients with Sepsis-3 organ dysfunction did not meet Sepsis-2 criteria. Increasing numbers of Sepsis-2 organ system dysfunctions were associated with greater mortality. Conclusions SIRS was associated with organ dysfunction and mortality, and abandoning the concept appears premature. A qSOFA score\ua0≥ 2 showed high specificity, but poor sensitivity may limit utility as a bedside screening method. Although mortality for organ dysfunction was comparable between Sepsis-2 and Sepsis-3, more prognostic and clinical information is conveyed using Sepsis-2 regarding number and type of organ dysfunctions. The SOFA score may require recalibration
Effective cerebral connectivity during silent speech reading revealed by functional magnetic resonance imaging
Primary and malignant cholangiocytes undergo CD40 mediated Fas dependent Apoptosis, but are insensitive to direct activation with exogenous fas ligand
Introduction
Cholangiocarcinoma is a rare malignancy of the biliary tract, the incidence of which is rising, but the pathogenesis of which remains uncertain. No common genetic defects have been described but it is accepted that chronic inflammation is an important contributing factor. We have shown that primary human cholangiocyte and hepatocyte survival is tightly regulated via co-operative interactions between two tumour necrosis family (TNF) receptor family members; CD40 and Fas (CD95). Functional deficiency of CD154, the ligand for CD40, leads to a failure of clearance of biliary tract infections and a predisposition to cholangiocarcinoma implying a direct link between TNF receptor-mediated apoptosis and the development of cholangiocarcinoma.
Aims
To determine whether malignant cholangiocytes display defects in CD40 mediated apoptosis. By comparing CD40 and Fas-mediated apoptosis and intracellular signalling in primary human cholangiocytes and three cholangiocyte cell lines.
Results
Primary cholangiocytes and cholangiocyte cell lines were relatively insensitive to direct Fas-mediated killing with exogenous FasL when compared with Jurkat cells, which readily underwent Fas-mediated apoptosis, but were extremely sensitive to CD154 stimulation. The sensitivity of cells to CD40 activation was similar in magnitude in both primary and malignant cells and was STAT-3 and AP-1 dependent in both.
Conclusions
1) Both primary and malignant cholangiocytes are relatively resistant to Fas–mediated killing but show exquisite sensitivity to CD154, suggesting that the CD40 pathway is intact and fully functional in both primary and malignant cholangiocytes 2) The relative insensitivity of cholangiocytes to Fas activation demonstrates the importance of CD40 augmentation of Fas dependent death in these cells. Agonistic therapies which target CD40 and associated intracellular signalling pathways may be effective in promoting apoptosis of malignant cholangiocytes
WWER-1000 Nuclear reactor simulator for education. Part A': Overview of simulator physico-mathematical model components
A review of phylogenetic studies carried out together with morphological ones shows that a major problem with most early studies is that they concentrated on techniques and used material or strains of fungi that in most cases were not carefully reference, and in a worrying number of cases wrongly named. Most classical species, particularly of microfungi, are not represented by adequate type material, or other authoritatively identified cultures or specimens, that can serve as DNA sources for phylogenetic study, or for developing robust identification systems. Natural classifications of fungi therefore suffer from the lack of reference strains in resultant phylogenetic trees. In some cases, epitypification and neotypification can solve this problem and these tools are increasingly used to resolve taxonomic confusion and stabilize the understanding of species, genera, families, or orders of fungi. This manuscript discusses epitypification and neotypification, describes how to epitypify or neotypify species and examines the importance of this process. A set of guidelines for epitypification is presented. Examples where taxa have been epitypified are presented and the benefits and problems of epitypification are discussed. As examples of epitypification, or to provide reference specimens, a new epitype is designated for Paraphaeosphaeria michotii and reference specimens are provided for Astrosphaeriella stellata, A. bakeriana, Phaeosphaeria elongata, Ophiobolus cirsii, and O. erythrosporus. In this way we demonstrate how to epitypify taxa and its importance, and also illustrate the value of proposing reference specimens if epitypification is not advisable. Although we provided guidelines for epitypification, the decision to epitypify or not lies with the author, who should have experience of the fungus concerned. This responsibility is to be taken seriously, as once a later typification is made, it may not be possible to undo that, particularly in the case of epitypes, without using the lengthy and tedious formal conservation and rejection processes
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