1,498 research outputs found
EL NOMOS DE LA REVUELTA: LA HUELGA ESTUDIANTIL DE LA UNIVERSIDAD DE PUERTO RICO (2010)
El objetivo de la presente investigaci\uf3n es auscultar y problematizar sobre la capacidad del movimiento estudiantil, en el contexto de la huelga de estudiantes de 2010 en la Universidad de Puerto Rico, de producir una normatividad aut\uf3noma m\ue1s all\ue1 de la jur\ueddica para garantizar su propio funcionamiento y durabilidad. Se trata de explorar la producci\uf3n normativa aut\uf3noma al margen del Estado como modo alternativo de regulaci\uf3n social, como una experiencia concreta de ese pluralismo jur\ueddico y normativo del que nos habla Jean Carbonnier (1974), entre otros, como objeto de investigaci\uf3n y estudio fundamental de la sociolog\ueda jur\ueddica en estos tiempos. En el caso espec\uedfico objeto de nuestro estudio, \ue9ste corresponde a un periodo \ue1lgido de proliferaci\uf3n de revueltas estudiantiles y juveniles a nivel internacional que se expresaran, adem\ue1s de Puerto Rico en lugares como Chile, California, Nueva York, Quebec, Grecia, Egipto, Espa\uf1a, Estados Unidos, entre otros
The effect of reinfection and mixed Trypanosoma cruzi infections on disease progression in mice
The progression of Chagas disease (CD) varies significantly from host to host and is affected by multiple factors. In particular, mixed strain infections and reinfections have the potential to exacerbate disease progression subsequently affecting clinical management of patients with CD. Consequently, an associated reduction in therapeutic intervention and poor prognosis may occur due to this exacerbated disease state.
This study investigated the effects of mixed strain infections and reinfection with Trypanosoma cruzi in mice, using two isolates from different discrete typing units, TcI (C8 clone 1) and TcIV (10R26). There were no significant differences in mortality rate, body weight or body condition among mice infected with either C8 clone 1, 10R26, or a mixture of both isolates. However, the parasite was found in a significantly greater number of host organs in mice infected with a mixture of isolates, and the histopathological response to infection was significantly greater in mice infected with C8 clone 1 alone, and C8 clone 1 + 10R26 mixed infections than in mice infected with 10R26 alone.
To investigate the effects of reinfection, mice received either a double exposure to C8 clone 1; a double exposure to 10R26; exposure to C8 clone 1 followed by 10R26; or exposure to 10R26 followed by C8 done 1. Compared to single infection groups, mortality was significantly increased, while survival time, body weight and body condition were all significantly decreased across all reinfection groups, with no significant differences among these groups. The mortality rate over all reinfection groups was 63.6%, compared to 0% in single infection groups, however there was no evidence of a greater histopathological response to infection.
These results suggest firstly, that the C8 clone 1 isolate is more virulent than the 10R26 isolate, and secondly, that a more disseminated infection may occur with a mixture of isolates than with single isolates, although there is no evidence that mixed infections have a greater pathological effect. By contrast, reinfections do have major effects on host survivability and thus disease outcome. This confirms previous research demonstrating spontaneous deaths following reinfection, a phenomenon that to our knowledge has only been reported once before
Replica Symmetry Breaking in Attractor Neural Network Models
The phenomenon of replica symmetry breaking is investigated for the retrieval
phases of Hopfield-type network models. The basic calculation is done for the
generalized version of the standard model introduced by Horner [1] and by
Perez-Vicente and Amit [2] which can exhibit low mean levels of neural
activity. For a mean activity the Hopfield model is recovered. In
this case, surprisingly enough, we cannot confirm the well known one step
replica symmetry breaking (1RSB) result for the storage capacity which was
presented by Crisanti, Amit and Gutfreund [3] (\alpha_c^{\hbox{\mf
1RSB}}\simeq 0.144). Rather, we find that 1RSB- and 2RSB-Ans\"atze yield only
slightly increased capacities as compared to the replica symmetric value
(\alpha_c^{\hbox{\mf 1RSB}}\simeq 0.138\,186 and \alpha_c^{\hbox{\mf
2RSB}}\simeq 0.138\,187 compared to \alpha_c^{\hbox{\mf RS}}\simeq
0.137\,905), significantly smaller also than the value \alpha_c^{\hbox{\mf
sim}} = 0.145\pm 0.009 reported from simulation studies. These values still
lie within the recently discovered reentrant phase [4]. We conjecture that in
the infinite Parisi-scheme the reentrant behaviour disappears as is the case in
the SK-spin-glass model (Parisi--Toulouse-hypothesis). The same qualitative
results are obtained in the low activity range.Comment: Latex file, 20 pages, 8 Figures available from the authors upon
request, HD-TVP-94-
Interruption of the Arterial Inferior Alveolar Flow and its Effects on Mandibular Collateral Circulation and Dental Tissues
The interruption of circulation through the inferior alveolar artery was followed by the establishment of a fast retrograde blood flow through the vessel. The mental artery and the mandibular branch of the sublingual artery were the main vessels to contribute to that flow. No histopathologic changes were found in the experimental hemimandibles; however, temporary regressive changes were found in the dental pulps of molars.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67920/2/10.1177_00220345750540040301.pd
Gauge Theories on a 2+2 Anisotropic Lattice
The implementation of gauge theories on a four-dimensional anisotropic
lattice with two distinct lattice spacings is discussed, with special attention
to the case where two axes are finely and two axes are coarsely discretized.
Feynman rules for the Wilson gauge action are derived and the renormalizability
of the theory and the recovery of the continuum limit are analyzed. The
calculation of the gluon propagator and the restoration of Lorentz invariance
in on-shell states is presented to one-loop order in lattice perturbation
theory for on both 2+2 and 3+1 lattices.Comment: 27 pages, uses feynmf. Font compatibility adjuste
Towards a formal description of the collapse approach to the inflationary origin of the seeds of cosmic structure
Inflation plays a central role in our current understanding of the universe.
According to the standard viewpoint, the homogeneous and isotropic mode of the
inflaton field drove an early phase of nearly exponential expansion of the
universe, while the quantum fluctuations (uncertainties) of the other modes
gave rise to the seeds of cosmic structure. However, if we accept that the
accelerated expansion led the universe into an essentially homogeneous and
isotropic space-time, with the state of all the matter fields in their vacuum
(except for the zero mode of the inflaton field), we can not escape the
conclusion that the state of the universe as a whole would remain always
homogeneous and isotropic. It was recently proposed in [A. Perez, H. Sahlmann
and D. Sudarsky, "On the quantum origin of the seeds of cosmic structure,"
Class. Quant. Grav. 23, 2317-2354 (2006)] that a collapse (representing physics
beyond the established paradigm, and presumably associated with a
quantum-gravity effect a la Penrose) of the state function of the inflaton
field might be the missing element, and thus would be responsible for the
emergence of the primordial inhomogeneities. Here we will discuss a formalism
that relies strongly on quantum field theory on curved space-times, and within
which we can implement a detailed description of such a process. The picture
that emerges clarifies many aspects of the problem, and is conceptually quite
transparent. Nonetheless, we will find that the results lead us to argue that
the resulting picture is not fully compatible with a purely geometric
description of space-time.Comment: 53 pages, no figures. Revision to match the published versio
Synapse efficiency diverges due to synaptic pruning following over-growth
In the development of the brain, it is known that synapses are pruned
following over-growth. This pruning following over-growth seems to be a
universal phenomenon that occurs in almost all areas -- visual cortex, motor
area, association area, and so on. It has been shown numerically that the
synapse efficiency is increased by systematic deletion. We discuss the synapse
efficiency to evaluate the effect of pruning following over-growth, and
analytically show that the synapse efficiency diverges as O(log c) at the limit
where connecting rate c is extremely small. Under a fixed synapse number
criterion, the optimal connecting rate, which maximize memory performance,
exists.Comment: 15 pages, 16 figure
Investigation into the epidemiology of African swine fever virus at the wildlife - domestic interface of the Gorongosa National Park, Central Mozambique
An epidemiological study of African swine fever (ASF) was conducted between
March 2006 and September 2007 in a rural area adjacent to the Gorongosa National
park (GNP) located in the Central Mozambique. Domestic pigs and warthogs were
sampled to determine the prevalence of antibodies against ASF virus and the salivary
antigens of Ornithodoros spp. ticks, while ticks collected from pig pens were
tested for the presence of ASFV. In addition, 310 framers were interviewed to gain a
better understanding of the pig value chain and potential practices that could
impact on the spread of the virus. The sero-prevalence to ASFV was 12.6% on
farms and 9.1% in pigs, while it reached 75% in warthogs. Approximately 33% of
pigs and 78% of warthogs showed antibodies against salivary antigens of ticks. The
differences in sero-prevalence between farms close to the GNP, where there is
greater chance for the sylvatic cycle to cause outbreaks, and farms located in the rest
of the district, where pig to pig transmission is more likely to occur, were marginally
significant. Ornithodoros spp. ticks were found in only 2 of 20 pig pens outside
the GNP, and both pens had ticks testing positive for ASFV DNA. Interviews carried
out among farmers indicated that biosecurity measures were mostly absent.
Herd sizes were small with pigs kept in a free-ranging husbandry system (65%).
Only 1.6% of farmers slaughtered on their premises, but 51% acknowledged allowing
visitors into their farms to purchase pigs. ASF outbreaks seemed to have a
severe economic impact with nearly 36% of farmers ceasing pig farming for at least
1 year after a suspected ASF outbreak. This study provides the first evidence of the
existence of a sylvatic cycle in Mozambique and confirms the presence of a permanent
source of virus for the domestic pig value chain.Wellcome Trust (Project number 210183. 183 AHDW03/04).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1865-16822017-08-30hb201
Introduction to Loop Quantum Gravity
This article is based on the opening lecture at the third quantum geometry
and quantum gravity school sponsored by the European Science Foundation and
held at Zakopane, Poland in March 2011. The goal of the lecture was to present
a broad perspective on loop quantum gravity for young researchers. The first
part is addressed to beginning students and the second to young researchers who
are already working in quantum gravity.Comment: 30 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:gr-qc/041005
Magnetic induction responses of Jupiter's ocean moons including effects from adiabatic convection
Prior analyses of oceanic magnetic induction within Jupiter's large icy moons have assumed uniform electrical conductivity. However, the phase and amplitude responses of the induced fields will be influenced by the natural depth‐dependence of the electrical conductivity. Here, we examine the amplitudes and phase delays for magnetic diffusion in modeled oceans of Europa, Ganymede, and Callisto. For spherically symmetric configurations, we consider thermodynamically consistent interior structures that include realistic electrical conductivity along the oceans' adiabatic temperature profiles. Conductances depend strongly on salinity, especially in the large moons. The induction responses of the adiabatic profiles differ from those of oceans with uniform conductivity set to values at the ice–ocean interface, or to the mean values of the adiabatic profile, by more than 10% for some signals. We also consider motionally induced magnetic fields generated by convective fluid motions within the oceans, which might optimistically be used to infer ocean flows or, pessimistically, act to bias the ocean conductivity inversions. Our upper‐bound scaling estimates suggest this effect may be important at Europa and Ganymede, with a negligible contribution at Callisto. Based on end‐member ocean compositions, we quantify the magnetic induction signals that might be used to infer the oxidation state of Europa's ocean and to investigate stable liquids under high‐pressure ices in Ganymede and Callisto. Fully exploring this parameter space for the sake of planned missions requires thermodynamic and electrical conductivity measurements in fluids at low temperature and to high‐salinity and pressure as well as modeling of motional induction responses
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