636 research outputs found
Sensitization and desensitization of burn patients as potential candidates for vascularized composite allotransplantation
Sensitization describes the acquired ability of the immune system to react to foreign human leukocyte antigens (HLA) by producing antibodies and developing memory cells. In the field of transplantation, recipient preformed HLA antibodies due to previous sensitization have been identified - beneath ABO incompatibility - as a major factor for acute graft rejection. Several reasons for sensitization have largely been studied, such as previous blood transfusions, pregnancies or former transplants. Recent studies indicate that the use of assist devices (e.g. ECMO) or cadaveric skin allotransplantation providing temporary coverage in burn patients may lead to additional sensitization. As vascularized composite allotransplantation (VCA) has become a rapidly advancing therapeutic option for reconstruction of complex tissue defects in burns, it seems even more important to become familiar with immunological principles and to be cautiously aware of both sources of sensitization and therapeutic concepts in burns avoiding sensitization. This may also include emergency VCAs in burn patients as potential strategy for early definitive reconstruction avoiding procedures triggering HLA antibody formation. We hereby provide an overview on current evidence in the field of pre- and peritrans-plant sensitization, followed by posttransplant strategies of desensitization and their potential impact on future treatments of burn patients. (C) 2015 Elsevier Ltd and ISBI. All rights reserved.Peer reviewe
An investigation of standard thermodynamic quantities as determined via models of nuclear multifragmentation
Both simple and sophisticated models are frequently used in an attempt to
understand how real nuclei breakup when subjected to large excitation energies,
a process known as nuclear multifragmentation. Many of these models assume
equilibriumthermodynamics and produce results often interpreted as evidence of
a phase transition. This work examines one class of models and employs standard
thermodynamical procedure to explore the possible existence and nature of a
phase transition. The role of various terms, e.g. Coulomb and surface energy,
is discussed.Comment: 19 two-column format pages with 24 figure
The liquid to vapor phase transition in excited nuclei
For many years it has been speculated that excited nuclei would undergo a
liquid to vapor phase transition. For even longer, it has been known that
clusterization in a vapor carries direct information on the liquid- vapor
equilibrium according to Fisher's droplet model. Now the thermal component of
the 8 GeV/c pion + 197Au multifragmentation data of the ISiS Collaboration is
shown to follow the scaling predicted by Fisher's model, thus providing the
strongest evidence yet of the liquid to vapor phase transition.Comment: four pages, four figures, first two in color (corrected typo in Ref.
[26], corrected error in Fig. 4
The postulates of gravitational thermodynamics
The general principles and logical structure of a thermodynamic formalism
that incorporates strongly self-gravitating systems are presented. This
framework generalizes and simplifies the formulation of thermodynamics
developed by Callen. The definition of extensive variables, the homogeneity
properties of intensive parameters, and the fundamental problem of
gravitational thermodynamics are discussed in detail. In particular, extensive
parameters include quasilocal quantities and are naturally incorporated into a
set of basic general postulates for thermodynamics. These include additivity of
entropies (Massieu functions) and the generalized second law. Fundamental
equations are no longer homogeneous first-order functions of their extensive
variables. It is shown that the postulates lead to a formal resolution of the
fundamental problem despite non-additivity of extensive parameters and
thermodynamic potentials. Therefore, all the results of (gravitational)
thermodynamics are an outgrowth of these postulates. The origin and nature of
the differences with ordinary thermodynamics are analyzed. Consequences of the
formalism include the (spatially) inhomogeneous character of thermodynamic
equilibrium states, a reformulation of the Euler equation, and the absence of a
Gibbs-Duhem relation.Comment: 28 pages, Revtex, no figures. An important sentence and several minor
corrections included. To appear in Physical Review
Probability Theory Compatible with the New Conception of Modern Thermodynamics. Economics and Crisis of Debts
We show that G\"odel's negative results concerning arithmetic, which date
back to the 1930s, and the ancient "sand pile" paradox (known also as "sorites
paradox") pose the questions of the use of fuzzy sets and of the effect of a
measuring device on the experiment. The consideration of these facts led, in
thermodynamics, to a new one-parameter family of ideal gases. In turn, this
leads to a new approach to probability theory (including the new notion of
independent events). As applied to economics, this gives the correction, based
on Friedman's rule, to Irving Fisher's "Main Law of Economics" and enables us
to consider the theory of debt crisis.Comment: 48p., 14 figs., 82 refs.; more precise mathematical explanations are
added. arXiv admin note: significant text overlap with arXiv:1111.610
Axial length growth and the risk of developing myopia in European children
PURPOSE:
To generate percentile curves of axial length (AL) for European children, which can be used to estimate the risk of myopia in adulthood.
METHODS:
A total of 12 386 participants from the population-based studies Generation R (Dutch children measured at both 6 and 9 years of age; N = 6934), the Avon Longitudinal Study of Parents and Children (ALSPAC) (British children 15 years of age; N = 2495) and the Rotterdam Study III (RS-III) (Dutch adults 57 years of age; N = 2957) contributed to this study. Axial length (AL) and corneal curvature data were available for all participants; objective cycloplegic refractive error was available only for the Dutch participants. We calculated a percentile score for each Dutch child at 6 and 9 years of age.
RESULTS:
Mean (SD) AL was 22.36 (0.75) mm at 6 years, 23.10 (0.84) mm at 9 years, 23.41 (0.86) mm at 15 years and 23.67 (1.26) at adulthood. Axial length (AL) differences after the age of 15 occurred only in the upper 50%, with the highest difference within the 95th percentile and above. A total of 354 children showed accelerated axial growth and increased by more than 10 percentiles from age 6 to 9 years; 162 of these children (45.8%) were myopic at 9 years of age, compared to 4.8% (85/1781) for the children whose AL did not increase by more than 10 percentiles.
CONCLUSION:
This study provides normative values for AL that can be used to monitor eye growth in European children. These results can help clinicians detect excessive eye growth at an early age, thereby facilitating decision-making with respect to interventions for preventing and/or controlling myopia
Spin-transfer in an open ferromagnetic layer: from negative damping to effective temperature
Spin-transfer is a typical spintronics effect that allows a ferromagnetic
layer to be switched by spin-injection. Most of the experimental results about
spin transfer are described on the basis of the Landau-Lifshitz-Gilbert
equation of the magnetization, in which additional current-dependent damping
factors are added, and can be positive or negative. The origin of the damping
can be investigated further by performing stochastic experiments, like one shot
relaxation experiments under spin-injection in the activation regime of the
magnetization. In this regime, the N\'eel-Brown activation law is observed
which leads to the introduction of a current-dependent effective temperature.
In order to justify the introduction of these counterintuitive parameters
(effective temperature and negative damping), a detailed thermokinetic analysis
of the different sub-systems involved is performed. We propose a thermokinetic
description of the different forms of energy exchanged between the electric and
the ferromagnetic sub-systems at a Normal/Ferromagnetic junction. The
corresponding Fokker Planck equations, including relaxations, are derived. The
damping coefficients are studied in terms of Onsager-Casimir transport
coefficients, with the help of the reciprocity relations. The effective
temperature is deduced in the activation regime.Comment: 65 pages, 10 figure
Notes on the Third Law of Thermodynamics.I
We analyze some aspects of the third law of thermodynamics. We first review
both the entropic version (N) and the unattainability version (U) and the
relation occurring between them. Then, we heuristically interpret (N) as a
continuity boundary condition for thermodynamics at the boundary T=0 of the
thermodynamic domain. On a rigorous mathematical footing, we discuss the third
law both in Carath\'eodory's approach and in Gibbs' one. Carath\'eodory's
approach is fundamental in order to understand the nature of the surface T=0.
In fact, in this approach, under suitable mathematical conditions, T=0 appears
as a leaf of the foliation of the thermodynamic manifold associated with the
non-singular integrable Pfaffian form . Being a leaf, it cannot
intersect any other leaf const. of the foliation. We show that (N) is
equivalent to the requirement that T=0 is a leaf. In Gibbs' approach, the
peculiar nature of T=0 appears to be less evident because the existence of the
entropy is a postulate; nevertheless, it is still possible to conclude that the
lowest value of the entropy has to belong to the boundary of the convex set
where the function is defined.Comment: 29 pages, 2 figures; RevTex fil
Statistical signatures of critical behavior in small systems
The cluster distributions of different systems are examined to search for
signatures of a continuous phase transition. In a system known to possess such
a phase transition, both sensitive and insensitive signatures are present;
while in systems known not to possess such a phase transition, only insensitive
signatures are present. It is shown that nuclear multifragmentation results in
cluster distributions belonging to the former category, suggesting that the
fragments are the result of a continuous phase transition.Comment: 31 pages, two columns with 30 figure
Associations with photoreceptor thickness measures in the UK Biobank.
Spectral-domain OCT (SD-OCT) provides high resolution images enabling identification of individual retinal layers. We included 32,923 participants aged 40-69 years old from UK Biobank. Questionnaires, physical examination, and eye examination including SD-OCT imaging were performed. SD OCT measured photoreceptor layer thickness includes photoreceptor layer thickness: inner nuclear layer-retinal pigment epithelium (INL-RPE) and the specific sublayers of the photoreceptor: inner nuclear layer-external limiting membrane (INL-ELM); external limiting membrane-inner segment outer segment (ELM-ISOS); and inner segment outer segment-retinal pigment epithelium (ISOS-RPE). In multivariate regression models, the total average INL-RPE was observed to be thinner in older aged, females, Black ethnicity, smokers, participants with higher systolic blood pressure, more negative refractive error, lower IOPcc and lower corneal hysteresis. The overall INL-ELM, ELM-ISOS and ISOS-RPE thickness was significantly associated with sex and race. Total average of INL-ELM thickness was additionally associated with age and refractive error, while ELM-ISOS was additionally associated with age, smoking status, SBP and refractive error; and ISOS-RPE was additionally associated with smoking status, IOPcc and corneal hysteresis. Hence, we found novel associations of ethnicity, smoking, systolic blood pressure, refraction, IOPcc and corneal hysteresis with photoreceptor thickness
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