236 research outputs found
Weak-field approximation of effective gravitational theory with local Galilean invariance
We examine the weak-field approximation of locally Galilean invariant
gravitational theories with general covariance in a -dimensional
Galilean framework. The additional degrees of freedom allow us to obtain
Poisson, diffusion, and Schr\"odinger equations for the fluctuation field. An
advantage of this approach over the usual -dimensional General
Relativity is that it allows us to choose an ansatz for the fluctuation field
that can accommodate the field equations of the Lagrangian approach to MOdified
Newtonian Dynamics (MOND) known as AQUAdratic Lagrangian (AQUAL). We
investigate a wave solution for the Schr\"odinger equations.Comment: 15 page
Path-integral quantization of Galilean Fermi fields
The Galilei-covariant fermionic field theories are quantized by using the
path-integral method and five-dimensional Lorentz-like covariant expressions of
non-relativistic field equations. Firstly, we review the five-dimensional
approach to the Galilean Dirac equation, which leads to the Levy-Leblond
equations, and define the Galilean generating functional and Green's functions
for positive- and negative-energy/mass solutions. Then, as an example of
interactions, we consider the quartic self-interacting potential , and we derive expressions for the 2- and 4-point
Green's functions. Our results are compatible with those found in the
literature on non-relativistic many-body systems. The extended manifold allows
for compact expressions of the contributions in space-time. This is
particularly apparent when we represent the results with diagrams in the
extended manifold, since they usually encompass more diagrams in
Galilean space-time.Comment: LATEX file, 27 pages, 8 figures; typos in the journal version are
removed, equation (1) in Introduction is correcte
Non-linear Liouville and Shr\"odinger equations in phase space
Unitary representations of the Galilei group are studied in phase space, in
order to describe classical and quantum systems. Conditions to write in general
form the generator of time translation and Lagrangians in phase space are then
established. In the classical case, Galilean invariance provides conditions for
writing the Liouville operator and Lagrangian for non-linear systems. We
analyze, as an example, a generalized kinetic equation where the collision term
is local and non-linear. The quantum counter-part of such unitary
representations are developed by using the Moyal (or star) product. Then a
non-linear Schr\"odinger equation in phase space is derived and analyzed. In
this case, an association with the Wigner formalism is established, which
provides a physical interpretation for the formalism
Growth inhibitory effects of 3′-nitro-3-phenylamino nor-beta-lapachone against HL-60: A redox-dependent mechanism
AbstractIn this study, the cytotoxicity, genotoxicity and early ROS generation of 2,2-dimethyl-(3H)-3-(N-3′-nitrophenylamino)naphtho[1,2-b]furan-4,5-dione (QPhNO2) were investigated and compared with those of its precursor, nor-beta-lapachone (nor-beta), with the main goal of proposing a mechanism of antitumor action. The results were correlated with those obtained from electrochemical experiments held in protic (acetate buffer pH 4.5) and aprotic (DMF/TBABF4) media in the presence and absence of oxygen and with those from dsDNA biosensors and ssDNA in solution, which provided evidence of a positive interaction with DNA in the case of QPhNO2. QPhNO2 caused DNA fragmentation and mitochondrial depolarization and induced apoptosis/necrosis in HL-60 cells. Pre-treatment with N-acetyl-l-cysteine partially abolished the observed effects related to the QPhNO2 treatment, including those involving apoptosis induction, indicating a partially redox-dependent mechanism. These findings point to the potential use of the combination of pharmacology and electrochemistry in medicinal chemistry
Triterpenos pentacíclicos e esteróides da casca do uchi (Sacoglottis uchi, Humiriaceae)
The ethanol extract from stem bark of Sacoglottis uchi Huber (popularly known as \x93uchi\x94 in the Amazon Region) was submitted to chromatographic fractionation. The dichloromethane fractions provided the pentacyclic triterpene 3-oxo-friedelin (1). The dichloromethane:methanol fractions provided the pentacyclic triterpenes pseudotaraxasterol (2), lupeol (3), a-amyrin (4), betulin (5), and methyl 2ß,3ß-dihydroxy-urs-12-en-28-oate (6) and a mixture of the steroids sitosterol (7) and stigmasterol (8). Their chemical structures were determined by NMR spectroscopy and comparison with spectroscopic data from the literature. All compounds are described for the first time in this species.O extrato etanólico da casca do caule de Sacoglottis uchi Huber (conhecida popularmente como \x93uchi\x94 na Amazônia) foi submetido a fracionamento cromatográfico. As frações eluídas com diclorometano forneceram o triterpeno pentacíclico 3-oxo-friedelina (1). As frações em diclorometano:metanol forneceram os triterpenos pentacíclicos pseudotaraxasterol (2), lupeol (3), a-amirina (4), betulina (5) e 2ß,3ß-di-hidroxi-urs-12-en-28-oato de metila (6), além de uma mistura dos esteróides sitosterol (7) e estigmasterol (8). Suas estruturas químicas foram determinadas por espectroscopia de RMN e comparação com os dados espectroscópicos descritos na literatura. Todas as substâncias isoladas são descritas pela primeira vez nesta espécie
Measurement of Bose-Einstein Correlations in e+e- -> W+W- at root(s)=189GeV
We investigate Bose-Einstein correlations (BEC) in W-pair production at
root(s)=189GeV using the L3 detector at LEP. We observe BEC between particles
from a single W decay in good agreement with those from a light-quark Z decay
sample. We investigate their possible existence between particles coming from
different W's. No evidence for such inter-W BEC is found
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