355 research outputs found
A spatially-VSL gravity model with 1-PN limit of GRT
A scalar gravity model is developed according the 'geometric conventionalist'
approach introduced by Poincare (Einstein 1921, Poincare 1905, Reichenbach
1957, Gruenbaum1973). In principle this approach allows an alternative
interpretation and formulation of General Relativity Theory (GRT), with
distinct i) physical congruence standard, and ii) gravitation dynamics
according Hamilton-Lagrange mechanics, while iii) retaining empirical
indistinguishability with GRT. In this scalar model the congruence standards
have been expressed as gravitationally modified Lorentz Transformations
(Broekaert 2002). The first type of these transformations relate quantities
observed by gravitationally 'affected' (natural geometry) and 'unaffected'
(coordinate geometry) observers and explicitly reveal a spatially variable
speed of light (VSL). The second type shunts the unaffected perspective and
relates affected observers, recovering i) the invariance of the locally
observed velocity of light, and ii) the local Minkowski metric (Broekaert
2003). In the case of a static gravitation field the model retrieves the
phenomenology implied by the Schwarzschild metric. The case with proper source
kinematics is now described by introduction of a 'sweep velocity' field w: The
model then provides a hamiltonian description for particles and photons in full
accordance with the first Post-Newtonian approximation of GRT (Weinberg 1972,
Will 1993).Comment: v1: 11 pages, GR17 conf. paper, Dublin 2004, v2: WEP issue solved,
section on acceleration transformation added, text improved, more references,
same results, v3: typos removed, footnotes, added and references updated, v4:
appendix added, improved tex
Quantum Experimental Data in Psychology and Economics
We prove a theorem which shows that a collection of experimental data of
probabilistic weights related to decisions with respect to situations and their
disjunction cannot be modeled within a classical probabilistic weight structure
in case the experimental data contain the effect referred to as the
'disjunction effect' in psychology. We identify different experimental
situations in psychology, more specifically in concept theory and in decision
theory, and in economics (namely situations where Savage's Sure-Thing Principle
is violated) where the disjunction effect appears and we point out the common
nature of the effect. We analyze how our theorem constitutes a no-go theorem
for classical probabilistic weight structures for common experimental data when
the disjunction effect is affecting the values of these data. We put forward a
simple geometric criterion that reveals the non classicality of the considered
probabilistic weights and we illustrate our geometrical criterion by means of
experimentally measured membership weights of items with respect to pairs of
concepts and their disjunctions. The violation of the classical probabilistic
weight structure is very analogous to the violation of the well-known Bell
inequalities studied in quantum mechanics. The no-go theorem we prove in the
present article with respect to the collection of experimental data we consider
has a status analogous to the well known no-go theorems for hidden variable
theories in quantum mechanics with respect to experimental data obtained in
quantum laboratories. For this reason our analysis puts forward a strong
argument in favor of the validity of using a quantum formalism for modeling the
considered psychological experimental data as considered in this paper.Comment: 15 pages, 4 figure
Fat induces glucose metabolism in nontransformed liver cells and promotes liver tumorigenesis
Hepatic fat accumulation is associated with diabetes and hepatocellular carcinoma (HCC). Here, we characterize the metabolic response that high-fat availability elicits in livers before disease development. After a short term on a high-fat diet (HFD), otherwise healthy mice showed elevated hepatic glucose uptake and increased glucose contribution to serine and pyruvate carboxylase activity compared with control diet (CD) mice. This glucose phenotype occurred independently from transcriptional or proteomic programming, which identifies increased peroxisomal and lipid metabolism pathways. HFD-fed mice exhibited increased lactate production when challenged with glucose. Consistently, administration of an oral glucose bolus to healthy individuals revealed a correlation between waist circumference and lactate secretion in a human cohort. In vitro, palmitate exposure stimulated production of reactive oxygen species and subsequent glucose uptake and lactate secretion in hepatocytes and liver cancer cells. Furthermore, HFD enhanced the formation of HCC compared with CD in mice exposed to a hepatic carcinogen. Regardless of the dietary background, all murine tumors showed similar alterations in glucose metabolism to those identified in fat exposed nontransformed mouse livers, however, particular lipid species were elevated in HFD tumor and nontumor-bearing HFD liver tissue. These findings suggest that fat can induce glucose-mediated metabolic changes in nontransformed liver cells similar to those found in HCC
Prospects in Analytical Atomic Spectrometry
Tendencies in five main branches of atomic spectrometry (absorption,
emission, mass, fluorescence and ionization spectrometry) are considered. The
first three techniques are the most widespread and universal, with the best
sensitivity attributed to atomic mass spectrometry. In the direct elemental
analysis of solid samples, the leading roles are now conquered by laser-induced
breakdown and laser ablation mass spectrometry, and the related techniques with
transfer of the laser ablation products into inductively-coupled plasma.
Advances in design of diode lasers and optical parametric oscillators promote
developments in fluorescence and ionization spectrometry and also in absorption
techniques where uses of optical cavities for increased effective absorption
pathlength are expected to expand. Prospects for analytical instrumentation are
seen in higher productivity, portability, miniaturization, incorporation of
advanced software, automated sample preparation and transition to the
multifunctional modular architecture. Steady progress and growth in
applications of plasma- and laser-based methods are observed. An interest
towards the absolute (standardless) analysis has revived, particularly in the
emission spectrometry.Comment: Proofread copy with an added full reference list of 279 citations. A
pdf version of the final published review may be requested from Alexander
Bol'shakov <[email protected]
Heterostructures for High Performance Devices
Contains table of contents for Part I, table of contents for Section 1, an introduction, reports on eighteen research projects and a list of publications.Charles S. Draper Laboratories Contract DL-H-418483DARPA/NCIPTJoint Services Electronics Program Contract DAAL03-89-C-0001Joint Services Electronics Program Contract DAAL03-92-C-0001IBM Corporation FellowshipNational Science Foundation FellowshipVitesse SemiconductorGTE LaboratoriesCharles S. Draper LaboratoriesElectronics and Telecommunications Research Institute (ETRI) FellowshipNational Science Foundation/Northeastern UniversityTRW SystemsU.S. Army Research OfficeNational Science FoundationAT&T Bell Laboratories FellowshipNational Science Foundation Grant ECS 90-0774
Heterostructures for Optical Devices
Contains research objectives and reports on eight research projects.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAALO3-89-C-0001)National Science Foundation (Grant EET 87-03404)Charles Stark Draper Laboratory (Contract DL-H-315251)Xerox Corporation FellowshipMIT Fund
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