458 research outputs found
Vertical Melting of a Stack of Membranes
A stack of tensionless membranes with nonlinear curvature energy and vertical
harmonic interaction is studied. At low temperatures, the system forms a
lamellar phase. At a critical temperature, the stack disorders vertically in a
melting-like transition.Comment: 8 pages, 2 figure
Decrumpling membranes by quantum effects
The phase diagram of an incompressible fluid membrane subject to quantum and
thermal fluctuations is calculated exactly in a large number of dimensions of
configuration space. At zero temperature, a crumpling transition is found at a
critical bending rigidity . For membranes of fixed lateral
size, a crumpling transition occurs at nonzero temperatures in an auxiliary
mean field approximation. As the lateral size L of the membrane becomes large,
the flat regime shrinks with .Comment: 9 pages, 4 figure
Rare human skin infection with Corynebacterium ulcerans: transmission by a domestic cat
Corynebacterium ulcerans is mainly known for its ability to cause animal infections. Some strains of C. ulcerans produce diphtheria toxin, which can cause life-threatening cardiopathies and neuropathies in humans. Human cutaneous C. ulcerans infection is a very rare disease that mimics classical cutaneous diphtheria. We present a very rare case of a C. ulcerans skin infection caused by a non-diphtheria toxin-producing strain of C. ulcerans that resolved after 3weeks of therapy with amoxicillin-clavulanate. A pet cat was the probable source of infection. The presence of C. ulcerans in the mouth of the cat was confirmed by 16S rRNA gene analysis and the API Coryne system. In cases of human infection with potentially toxigenic corynebacteria, it is important to determine the species and examine the isolate for diphtheria toxin production. If toxigenicity is present, diphtheria antitoxin should be administered immediately. Carriers and potential infectious sources of C. ulcerans include not only domestic livestock but also pet animals. For the primary prevention of disease caused by diphtheria toxin-producing corynebacteria, vaccination with diphtheria toxoid is recommende
Chiral Gauge Theory on Lattice with Domain Wall Fermions
We investigate a U(1) lattice chiral gauge theory with domain wall fermions
and compact gauge fixing. In the reduced model limit, our perturbative and
numerical investigations show that there exist no extra mirror chiral modes.
The longitudinal gauge degrees of freedom have no effect on the free domain
wall fermion spectrum consisting of opposite chiral modes at the domain wall
and at the anti-domain wall which have an exponentially damped overlap.Comment: 16 pages revtex, 5 postscript figures, PRD versio
Feasibility of a Pulsed Ponderomotive Phase Plate for Electron Beams
We propose a scheme for constructing a phase plate for use in an ultrafast
Zernike-type phase contrast electron microscope, based on the interaction of
the electron beam with a strongly focused, high-power femtosecond laser pulse
and a pulsed electron beam. Analytical expressions for the phase shift using
the time-averaged ponderomotive potential and a paraxial approximation for the
focused laser beam are presented, as well as more rigorous quasiclassical
simulations based on the quantum phase integral along classical, relativistic
electron trajectories in an accurate, non-paraxial description of the laser
beam. The results are shown to agree well unless the laser beam is focused to a
waist size below a wavelength. For realistic (off-the-shelf) laser parameters
the optimum phase shift of is shown to be achievable. When combined
with RF-cavity based electron chopping and compression techniques to produce
electron pulses, a femtosecond regime pulsed phase contrast microscope can be
constructed. The feasibility and robustness of the scheme are further
investigated using the simulations, leading to motivated choices for design
parameters such as wavelength, focus size and polarization.Comment: 16 pages, 6 figure
Enhancing the utility of antroduodenal manometry in pediatric intestinal pseudo-obstruction
BACKGROUND:
Antroduodenal manometry (ADM) and histopathology are currently employed to aid the diagnosis of pediatric intestinal pseudo-obstruction (PIPO). Limited data are available on the reliability of ADM analysis and its correlation with histopathology. We aimed to develop a protocol for enhanced analysis of ADM contractile patterns, including a scoring system, and explore whether this provided better correlation with histopathology.
METHODS:
Children referred with suspected PIPO between April 2012-December 2019 who underwent both ADM and full-thickness biopsies were included. ADM tracings were analyzed using both standard (conventional ADM) and novel (enhanced ADM) motility parameters. A novel ADM score (GLASS score) was generated based on the enhanced ADM analysis. Conventional and enhanced ADM analyses were then correlated with histopathology.
RESULTS:
Forty patients were included. Using conventional clinical criteria, 29 of these were diagnosed with PIPO and the other 11 with non-PIPO diagnoses. Twenty-three of the PIPO patients had abnormal histopathology: 6 myopathy, 4 neuropathy, 3 neuro-myopathy, and 10 non-specific changes. No agreement in diagnosis was found between conventional ADM analysis and histopathology (Ï° = 0.068; p = 0.197), whereas the latter significantly correlated with enhanced ADM analysis (Ï° = 0.191; p = 0.003). The enhanced ADM score was significantly higher in PIPO versus non-PIPO (16.0 vs. 8.0; p < 0.001).
CONCLUSIONS:
As opposed to conventional analysis protocols, the newly developed enhanced ADM analysis and associated score is not only able to discriminate between PIPO and non-PIPO patients, but also between distinct histopathological pathologies. Further studies are required to assess the utility of enhanced ADM analysis in larger populations
A polymorphism in the cachexia-associated gene INHBA predicts efficacy of regorafenib in patients with refractory metastatic colorectal cancer
Activin/myostatin signaling has a critical role not only in cachexia but also in tumor angiogenesis. Cachexia is a frequent complication among patients with advanced cancer and heavily pretreated patients. We aimed to evaluate the prognostic significance of cachexia-associated genetic variants in refractory metastatic colorectal cancer (mCRC) patients treated with regorafenib. Associations between twelve single nucleotide polymorphisms in 8 genes (INHBA, MSTN, ALK4, TGFBR1, ALK7, ACVR2B, SMAD2, FOXO3) and clinical outcome were evaluated in mCRC patients of three cohorts: a discovery cohort of 150 patients receiving regorafenib, a validation cohort of 80 patients receiving regorafenib and a control cohort of 128 receiving TAS-102. In the discovery cohort, patients with any G variant in FOXO3 rs12212067 had a significantly lower response rate (P = 0.031) and overall survival (OS) than those with a T/T in univariate analysis (4.5 vs. 7.6 months, hazard ratio [HR] = 1.63, 95% confidence interval [CI] = 1.09â2.46, P = 0.012). Among female patients, those with any G variant in INHBA rs2237432 had a significantly longer OS than those with an A/A in both univariate (7.6 vs. 4.3 months, HR = 0.57, 95%CI = 0.34â0.95, P = 0.021) and multivariable (HR = 0.53, 95%CI = 0.29â0.94, adjusted P = 0.031) analysis. This association was confirmed in female patients of the validation cohort, though without statistical significance (P = 0.059). Conversely, female patients with any G allele in the control group receiving TAS-102 did not show a longer OS. This was the first study evaluating the associations between polymorphisms in cachexia-associated genes and outcomes in refractory mCRC
Chiral Fermions on the Lattice through Gauge Fixing -- Perturbation Theory
We study the gauge-fixing approach to the construction of lattice chiral
gauge theories in one-loop weak-coupling perturbation theory. We show how
infrared properties of the gauge degrees of freedom determine the nature of the
continuous phase transition at which we take the continuum limit. The fermion
self-energy and the vacuum polarization are calculated, and confirm that, in
the abelian case, this approach can be used to put chiral gauge theories on the
lattice in four dimensions. We comment on the generalization to the nonabelian
case.Comment: 31 pages, 5 figures, two refs. adde
The Standard Model from a New Phase Transition on the Lattice
Several years ago it was conjectured in the so-called Roma Approach, that
gauge fixing is an essential ingredient in the lattice formulation of chiral
gauge theories. In this paper we discuss in detail how the gauge-fixing
approach may be realized. As in the usual (gauge invariant) lattice
formulation, the continuum limit corresponds to a gaussian fixed point, that
now controls both the transversal and the longitudinal modes of the gauge
field. A key role is played by a new phase transition separating a conventional
Higgs or Higgs-confinement phase, from a phase with broken rotational
invariance. In the continuum limit we expect to find a scaling region, where
the lattice correlators reproduce the euclidean correlation functions of the
target (chiral) gauge theory, in the corresponding continuum gauge.Comment: 16 pages, revtex, one figure. Clarifications made, mainly in sections
3 and 6 that deal with the fermion action, to appear in Phys Rev
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