Luis Salasar - Academia.edu (original) (raw)

Papers by Luis Salasar

Nuclear Instruments and …, 2004

... L. Perrone, N. Peshman, S. Petrera, P. Petrinca, D. Pham-Ngoc, P. Pham-Trung, T. Pierog, O. P... more ... L. Perrone, N. Peshman, S. Petrera, P. Petrinca, D. Pham-Ngoc, P. Pham-Trung, T. Pierog, O. Pisanti, N. Playez, E. Ponce, TA Porter, L ... A. Tripathi, G. Tristram, M. Trombley, D. Tscherniakhovski, P. Tuckey, V. Tunnicliffe, M. Urban, C. Uribe Estrada, JF Valdés, A. Vargas, C. Vargas ...

Manual therapy, 2009

This study presents data on the intra-and inter-rater reliability of palpation on normal and over... more This study presents data on the intra-and inter-rater reliability of palpation on normal and overweight subjects and shows the influence of palpation discrepancy on angular variability for a collected data set, using computer simulation. Thirty healthy males were recruited. Two physiotherapists identified 12 anatomical landmarks that enabled measurement of eight joint angles. Palpation discrepancy was determined by photographic recordings under ultraviolet light. Angular discrepancies were determined from photos of the subject's orthostatic posture. A computer simulation was developed to predict expected angular variation according to observed palpation discrepancy. The results showed that the inter-rater reliability was lower than the intra-rater reliability for both palpation and angle measurements. Palpation of the greater trochanter (GT), anterior superior iliac spine (ASIS), seventh cervical vertebra (C7) and femoral epicondyle (FE) showed larger discrepancies. The overweight group presented a significant difference in palpation discrepancy for ASIS (P < 0.03). Angular variations were associated with palpation discrepancies for trunk flexion (TF), hip flexion (HF) and pelvic inclination (PI). Therefore, measurements should be performed by a single rater, rather than by different raters, if reliable angular measurements are intended. Specific anatomical landmarks require careful identification. Simulation was useful for providing estimates of variations due to palpation discrepancy.

$Research paper thumbnail of Observation of the Suppression of the Flux of Cosmic Rays above 4× 10^{19} eV$

Physical Review Letters, 2008

The Journal of clinical …, 2009

Autophagy can promote cell survival or cell death, but the molecular basis underlying its dual ro... more Autophagy can promote cell survival or cell death, but the molecular basis underlying its dual role in cancer remains obscure. Here we demonstrate that Δ 9 -tetrahydrocannabinol (THC), the main active component of marijuana, induces human glioma cell death through stimulation of autophagy. Our data indicate that THC induced ceramide accumulation and eukaryotic translation initiation factor 2α (eIF2α) phosphorylation and thereby activated an ER stress response that promoted autophagy via tribbles homolog 3-dependent (TRB3-dependent) inhibition of the Akt/mammalian target of rapamycin complex 1 (mTORC1) axis. We also showed that autophagy is upstream of apoptosis in cannabinoid-induced human and mouse cancer cell death and that activation of this pathway was necessary for the antitumor action of cannabinoids in vivo. These findings describe a mechanism by which THC can promote the autophagic death of human and mouse cancer cells and provide evidence that cannabinoid administration may be an effective therapeutic strategy for targeting human cancers.

$Research paper thumbnail of Measurement of the Depth of Maximum of Extensive Air Showers above 10^{18} eV$

Physical Review Letters, 2010

We describe the measurement of the depth of maximum, X max , of the longitudinal development of a... more We describe the measurement of the depth of maximum, X max , of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10 18 eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are

Science, 2007

2. Equal areas on this plot represent equal exposure on the sky. The declination is on the vertic... more 2. Equal areas on this plot represent equal exposure on the sky. The declination is on the vertical axis. Declinations 0°, -30°, and -60°are marked (from the top) (the observatory zenith is close to dec = -30°). The observatory has more exposure to the AGN indicated by darker stars than those shown in lighter shades of red.

Diabetes …, 2004

Nonalcoholic steatohepatitis (NASH) represents an advanced stage of fatty liver disease developed... more Nonalcoholic steatohepatitis (NASH) represents an advanced stage of fatty liver disease developed in the absence of alcohol abuse. Its increasing prevalence in western countries, the diagnostic difficulties by noninvasive tests, and the possibility of progression to advanced fibrosis and even cirrhosis make NASH a challenge for hepatologists. NASH is frequently associated with type 2 diabetes and the metabolic syndrome, and several genetic and acquired factors are involved in its pathogenesis. Insulin resistance plays a central role in the development of a steatotic liver, which becomes vulnerable to additional injuries. Several cyclic mechanisms leading to selfenhancement of insulin resistance and hepatic accumulation of fat have been recently identified. Excess intracellular fatty acids, oxidant stress, tumor necrosis factor-␣, and mitochondrial dysfunction are causes of hepatocellular injury, thereby leading to disease progression and to the establishment of NASH. Intestinal bacterial overgrowth also plays a role, by increasing production of endogenous ethanol and proinflammatory cytokines. Therapeutic strategies aimed at modulating insulin resistance, normalizing lipoprotein metabolism, and downregulating inflammatory mediators with probiotics have promising potential.

Astroparticle …, 2010

Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotr... more Data collected by the Pierre Auger Observatory through 31 August 2007 showed evidence for anisotropy in the arrival directions of cosmic rays above the Greisen-Zatsepin-Kuz'min energy threshold, 6 × 10 19 eV. The anisotropy was measured by the fraction of arrival directions that are less than 3.1 • from the position of an active galactic nucleus within 75 Mpc (using the Véron-Cetty and Véron 12 th catalog). An updated measurement of this fraction is reported here using the arrival directions of cosmic rays recorded above the same energy threshold through 31 December 2009. The number of arrival directions has increased from 27 to 69, allowing a more precise measurement. The correlating fraction is (38 +7 −6 )%, compared with 21% expected for isotropic cosmic rays. This is down from the early estimate of (69 +11 −13 )%. The enlarged set of arrival directions is examined also in relation to other populations of nearby extragalactic objects: galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in hard X-rays by the Swift Burst Alert Telescope. A celestial region around the position of the radiogalaxy Cen A has the largest excess of arrival directions relative to isotropic expectations. The 2-point autocorrelation function is shown for the enlarged set of arrival directions and compared to the isotropic expectation.

Clinical …, 1998

which reacted to form a color with merocyanine dye (4); creatinine was hydrolyzed to creatine, wh... more which reacted to form a color with merocyanine dye (4); creatinine was hydrolyzed to creatine, which in a reaction cascade, led to production of hydrogen peroxide that was measured by triaryl imidazole leuco-dye (4); slides for phosphorus used the formation of an ammoniumphosphomolybdate complex and its reaction with p-methylaminophenol sulfate (5); and uric acid was determined by the uricase peroxidase method (6). The specific urine calibration was used.

Brazilian Journal of Probability and Statistics, 2010

In this article we propose a generalized negative binomial distribution, which is constructed bas... more In this article we propose a generalized negative binomial distribution, which is constructed based on an extended Poisson process (a generalization of the homogeneous Poisson process). This distribution is intended to model discrete data with presence of zero-inflation and over-dispersion. For a dataset on animal abundance which presents over-dispersion and a high frequency of zeros, a comparison between our extended distribution and other common distributions used for modeling this kind of data is addressed, supporting the fitting of the proposed model.

Physics Letters B, 2010

The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which... more The spectrum can be described by a broken power law E −γ with index γ = 3.3 below the ankle which is measured at log 10 (E ankle /eV) = 18.6. Above the ankle the spectrum is described by a power law with index 2.6 followed by a flux suppression, above about log 10 (E/eV) = 19.5, detected with high statistical significance.

Astroparticle …, 2008

Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival dir... more Data collected by the Pierre Auger Observatory provide evidence for anisotropy in the arrival directions of the cosmic rays with the highest energies, which are correlated with the positions of relatively nearby active galactic nuclei (AGN) . The correlation has maximum significance for cosmic rays with energy greater than ∼ 6 × 10 19 eV and AGN at a distance less than ∼ 75 Mpc. We have confirmed the anisotropy at a confidence level of more than 99% through a test with parameters specified a priori, using an independent data set. The observed correlation is compatible with the hypothesis that cosmic rays with the highest energies originate from extra-galactic sources close enough so that their flux is not significantly attenuated by interaction with the cosmic background radiation (the Greisen-Zatsepin-Kuz'min effect). The angular scale of the correlation observed is a few degrees, which suggests a predominantly light composition unless the magnetic fields are very weak outside the thin disk of our galaxy. Our present data do not identify AGN as the sources of cosmic rays unambiguously, and other candidate sources which are distributed as nearby AGN are not ruled out. We discuss the prospect of unequivocal identification of individual sources of the highest-energy cosmic rays within a few years of continued operation of the Pierre Auger Observatory.