112 research outputs found
Entropies, volumes, and Einstein metrics
We survey the definitions and some important properties of several asymptotic
invariants of smooth manifolds, and discuss some open questions related to
them. We prove that the (non-)vanishing of the minimal volume is a
differentiable property, which is not invariant under homeomorphisms. We also
formulate an obstruction to the existence of Einstein metrics on four-manifolds
involving the volume entropy. This generalizes both the Gromov--Hitchin--Thorpe
inequality and Sambusetti's obstruction.Comment: This is a substantial revision and expansion of the 2004 preprint,
which I prepared in spring of 2010 and which has since been published. The
version here is essentially the published one, minus the problems introduced
by Springer productio
Entropy production in Gaussian thermostats
We show that an arbitrary Anosov Gaussian thermostat on a surface is
dissipative unless the external field has a global potential
A construction method of Atanassov’s intuitionistic fuzzy sets for image processing
In this work we introduce a new construction method of Atanassov\u27s intuitionistic fuzzy sets (A-IFSs) from fuzzy sets. We use A-IFSs in image processing. We propose a new image magnification algorithm using A-IFSs. This algorithm is characterized by its simplicity and its efficiency
One image reduction algorithm for RGB color images
We investigate the problem of combining or aggregating several color values given in coding scheme RGB. For this reason, we study the problem of averaging values on lattices, and in particular on discrete product lattices. We study the arithemtic mean and the median on product lattices. We apply these aggregation functions in image reduction and we present a new algorithm based on the minimization of penalty functions on discrete product lattices
Anatomical basis of sleep
El sueño es un estado biológico activo, periódico,
en el que se distinguen las etapas NREM y REM, que se
alternan sucesivamente durante la noche. Intervienen
los relojes biolĂłgicos en la modulaciĂłn del sistema, asĂ
como neurotransmisores especĂficos. Se trata de una
red neuronal compleja, en la que intervienen diversas
zonas del sistema nervioso central. Los procesos onĂricos
están controlados además de forma neural.
Se resume la historia de las investigaciones sobre
el tema, desde el siglo XIX hasta nuestra Ă©poca. Hay
que destacar los recientes descubrimientos de Lugaresi
y su equipo, que, al describir el insomnio familiar
grave, dieron importancia al nĂşcleo dorsomedial del
tálamo en la instauración de la fase de sueño profundo.
Al grupo de Reinoso se debe el hallazgo de que el
“director de orquesta” en la instauración del sueño
REM es la zona ventral paramediana del nĂşcleo reticular
pontino ora
Stability of relative equilibria with singular momentum values in simple mechanical systems
A method for testing -stability of relative equilibria in Hamiltonian
systems of the form "kinetic + potential energy" is presented. This method
extends the Reduced Energy-Momentum Method of Simo et al. to the case of
non-free group actions and singular momentum values. A normal form for the
symplectic matrix at a relative equilibrium is also obtained.Comment: Partially rewritten. Some mistakes fixed. Exposition improve
Energy transfer in a fast-slow Hamiltonian system
We consider a finite region of a lattice of weakly interacting geodesic flows
on manifolds of negative curvature and we show that, when rescaling the
interactions and the time appropriately, the energies of the flows evolve
according to a non linear diffusion equation. This is a first step toward the
derivation of macroscopic equations from a Hamiltonian microscopic dynamics in
the case of weakly coupled systems
Linearization of Cohomology-free Vector Fields
We study the cohomological equation for a smooth vector field on a compact
manifold. We show that if the vector field is cohomology free, then it can be
embedded continuously in a linear flow on an Abelian group
Metals detected by ICP/MS in wound tissue of war injuries without fragments in Gaza
<p>Abstract</p> <p>Background</p> <p>The amount and identity of metals incorporated into "weapons without fragments" remain undisclosed to health personnel. This poses a long-term risk of assumption and contributes to additional hazards for victims because of increased difficulties with clinical management. We assessed if there was evidence that metals are embedded in "wounds without fragments" of victims of the Israeli military operations in Gaza in 2006 and 2009.</p> <p>Methods</p> <p>Biopsies of "wounds without fragments" from clinically classified injuries, amputation (A), charred (C), burns (B), multiple piercing wounds by White Phosphorus (WP) (M), were analyzed by ICP/MS for content in 32 metals.</p> <p>Results</p> <p>Toxic and carcinogenic metals were detected in folds over control tissues in wound tissues from all injuries: in A and C wounds (Al, Ti, Cu, Sr, Ba, Co, Hg, V, Cs and Sn), in M wounds (Al, Ti, Cu, Sr, Ba, Co and Hg) and in B wounds (Co, Hg, Cs, and Sn); Pb and U in wounds of all classes; B, As, Mn, Rb, Cd, Cr, Zn in wounds of all classes, but M; Ni was in wounds of class A. Kind and amounts of metals correlate with clinical classification of injuries, exposing a specific metal signature, similar for 2006 and 2009 samples.</p> <p>Conclusions</p> <p>The presence of toxic and carcinogenic metals in wound tissue is indicative of the presence in weapon inducing the injury. Metal contamination of wounds carries unknown long term risks for survivors, and can imply effects on populations from environmental contamination. We discuss remediation strategies, and believe that these data suggest the need for epidemiological and environmental surveys.</p
Teratogenicity of depleted uranium aerosols: A review from an epidemiological perspective
BACKGROUND: Depleted uranium is being used increasingly often as a component of munitions in military conflicts. Military personnel, civilians and the DU munitions producers are being exposed to the DU aerosols that are generated. METHODS: We reviewed toxicological data on both natural and depleted uranium. We included peer reviewed studies and gray literature on birth malformations due to natural and depleted uranium. Our approach was to assess the "weight of evidence" with respect to teratogenicity of depleted uranium. RESULTS: Animal studies firmly support the possibility that DU is a teratogen. While the detailed pathways by which environmental DU can be internalized and reach reproductive cells are not yet fully elucidated, again, the evidence supports plausibility. To date, human epidemiological data include case examples, disease registry records, a case-control study and prospective longitudinal studies. DISCUSSION: The two most significant challenges to establishing a causal pathway between (human) parental DU exposure and the birth of offspring with defects are: i) distinguishing the role of DU from that of exposure to other potential teratogens; ii) documentation on the individual level of extent of parental DU exposure. Studies that use biomarkers, none yet reported, can help address the latter challenge. Thoughtful triangulation of the results of multiple studies (epidemiological and other) of DU teratogenicity contributes to disentangling the roles of various potentially teratogenic parental exposures. This paper is just such an endeavor. CONCLUSION: In aggregate the human epidemiological evidence is consistent with increased risk of birth defects in offspring of persons exposed to DU
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