Detecting the Attenuation of Blazar Gamma-ray Emission by Extragalactic Background Light with GLAST

Gamma rays with energy above 10 GeV interact with optical-UV photons resulting in pair production. Therefore, a large sample of high redshift sources of these gamma rays can be used to probe the extragalactic background starlight (EBL) by examining the redshift dependence of the attenuation of the flux above 10 GeV. GLAST, the next generation high-energy gamma-ray telescope, will have the unique capability to detect thousands of gamma-ray blazars to redshifts of at least z=4, with sufficient angular resolution to allow identification of a large fraction of their optical counterparts. By combining established models of the gamma-ray blazar luminosity function, two different calculations of the high energy gamma-ray opacity due to EBL absorption, and the expected GLAST instrument performance to produce simulated fluxes and redshifts for the blazars that GLAST would detect, we demonstrate that these gamma-ray blazars have the potential to be a highly effective probe of the optical-UV EBL.Comment: 15 pages, AASTeX, 3 eps figures, accepted for publication in Ap

Visualizing evolution in real-time method for strain engineering

The adaptive landscape for an industrially relevant phenotype is determined by the effects of the genetic determinants on the fitness of the microbial system. Identifying the underlying adaptive landscape for a particular phenotype of interest will greatly enhance our abilities to engineer more robust microbial strains. Visualizing evolution in real-time (VERT) is a recently developed method based on in vitro adaptive evolution that facilitates the identification of fitter mutants throughout the course of evolution. Combined with high-throughput genomic tools, VERT can greatly enhance the mapping of adaptive landscapes of industrially relevant phenotypes in microbial systems, thereby expanding our knowledge on the parameters that can be used for strain engineering

Detecting the EBL Attenuation of Blazars with GLAST

The Large Area Telescope (LAT) on board GLAST (Gamma-ray Large Area Space Telescope) due for launch in late 2007 will study the gamma-ray sky in the energy range 20 MeV to >300 GeV. GLAST-LAT's improved sensitivity with respect to previous missions will increase the number of known gamma-ray blazars from about 100 to thousands, with redshifts up to z~3-5. Since gamma rays with energy above 10 GeV interact via pair-production with photons from the Extragalactic Background Light (EBL), the systematic attenuation of GLAST-detected blazars as a function of redshift would constitute and effective and unique probe of the optical-UV EBL density and its evolution over cosmic history. Analysis techniques introduced in this dissertation make use of the large number of blazars detected by GLAST to study the collective behavior of their spectra as a function of redshift. These techniques are shown to offer powerful ways to help separate the common level of attenuation due to the EBL from the intrinsic peculiarities of individual blazars. The capability of GLAST to perform these measurements depends in great measure on the acceptance of the instrument to high energy photons (E > 10 GeV), which in previous space-experiments has been drastically reduced due to backsplash self-veto. This dissertation includes a study of the backsplash effect as measured with flight-like detectors during a beam test of the LAT calibration unit. This analysis was used to verify the capabilities of the GLAST simulations tools to reproduce backsplash effects

Relación entre antecedentes heredofamiliares de Diabetes Mellitus con la presencia de manifestaciones clínicas de resistencia a la insulina (acantosis nigricans)

To establish the relationship between hereditary family history and the presence of acanthosis nigricans (AN) in order to determine its possible influence on the development of Type 2 Diabetes Mellitus. Material and methods: an analytical, observational, cross-sectional study was carried out. . The study population consisted of 40 patients between 18 and 25 years of age treated in the outpatient clinic of the General Hospital of Minatitlán and General Hospital of Oluta who presented Acanthosis Nigricans. Results: The prevalence of AN was 25%, with a female predominance of 88.8%. The most frequent site where it occurred was the neck with 50%. The prevalence of hereditary family history was 83%. AN is a factor associated with a family history of Diabetes Mellitus. (p<0.05). It was found that there is a relationship between family history of diabetes mellitus and the presence of clinical manifestations of insulin resistance (acanthosis nigricans) in patients at the General Hospital of Minatitlán and the General Hospital of Oluta, Veracruz.Establecer la relación de los antecedentes heredo familiares con la presencia de acantosis nigricans (AN) con el objetivo de determinar su posible influencia en el desarrollo de Diabetes Mellitus Tipo 2. Material y métodos: se llevó a cabo un estudio analítico, observacional, seccional transversal. La población de estudio estuvo constituida por 40 pacientes de 18 a 25 años de edad atendidos en la consulta externa del Hospital General de Minatitlán y Hospital General de Oluta que presentaran Acantosis Nigricans. Resultados: La prevalencia de AN fue de 25%, con una predominancia del género femenino de un 88.8%. El sitio más frecuente donde se presentó fue el cuello con un 50%. La prevalencia de antecedentes heredofamiliares fue de un 83%. La AN es factor asociado a antecedentes heredofamiliares de Diabetes Mellitus. (p<0.05). Se comprobó que existe relación entre antecedentes heredofamiliares de diabetes mellitus con la presencia de manifestaciones clínicas de resistencia a la insulina (acantosis nigricans) en pacientes del Hospital General de Minatitlán y el Hospital General de Oluta, Veracruz

Physiological Responses of Species to Microclimate Help explain Population Dynamics along Succession in a Tropical Dry Forest of Yucatan, Mexico

We investigated relationships between population dynamics and microclimate, physiology, and the degree of mycorrhizal colonization, for three species (Piscidia piscipula L.(Sarg.)) (Fabaceae), Bunchosia swartzianaGriseb. (Malpighiaceae) and Psidium sartorianum (Bergius) Nied. (Myrtaceae)) of a tropical sub deciduous forest in Yucatan, Mexico that were growing in plots of different successional ages. We hypothesized that abundance and persistence were related to increased plasticity in CO2assimilation. We found that Piscidia piscipula had greater abundance in intermediate plots (18 to 21 years), presented higher levels of plasticity in CO2 assimilation (greater variability among individuals, plots, and seasons), presented the highest CO2 assimilation rates, and presented greater drought resistance (higher water potentials and capacitance). Conversely, Psidium sartorianum had greater abundance in older plots (more than 50 years of secondary succession), lower assimilation rates, and low levels of plasticity in CO2 assimilation. Bunchosia had intermediate values. Locally, the degree of mycorrhizal colonization was consistent with abundance across plots. Regionally (but not locally), plasticity in CO2 assimilation was consistent with abundance. We found differences in microclimates among plots and within plots among species. Physiological adjustments appeared to play an important role in the capacity to regenerate and in the successional persistence of these species in this tropical dry forest

Comparación de los perfiles farmacodinámicos de tres moléculas de remifentanilo en cuanto a su respuesta hemodinámica a las maniobras de laringoscopia e intubación traqueal

ResumenIntroducciónEn Colombia se comercializan diferentes moléculas de remifentanilo que nunca han sido comparadas en un entorno clínico.ObjetivoEl objetivo de este estudio fue investigar el perfil farmacodinámico de la molécula innovadora de remifentanilo (grupo O: Glaxo SmithKline Manufacturing S.P.A.) y 2 moléculas genéricas (grupo A: Laboratorios Chalver de Colombia S.A. y grupo B: Instituto Biológico Contemporáneo, Argentina) registradas en Colombia.MétodosSe llevó a cabo un experimento clínico doble ciego, aleatorizado, controlado. Se comparó la molécula original de remifentanilo (grupo O, n=29) frente a las 2 moléculas genéricas (grupo A, n=29; grupo B, n=32) durante la inducción anestésica e intubación orotraqueal de pacientes adultos ASAI sin predictores de vía aérea difícil. Se evaluaron las dosis 6, 8 y 10ng/ml (TCI, Target Controlled Infusion) con el modelo de Minto. La inducción se complementó con propofol 5μg/ml (TCI) con modelo de Schneider y rocuronio 0,6mg/kg. El desenlace primario se evaluó como las diferencias en la presión arterial media y en la frecuencia cardiaca preintubación (momento en que se alcanza la concentración objetivo en sitio efecto) y postintubación (máximo valor alcanzado en 5min).ResultadosSe observó similitud en el perfil farmacodinámico de las moléculas de remifentanilo estudiadas. Las diferencias en el cambio de frecuencia cardiaca fue de 1,27 (IC95%: –3,11;5,67) con la molécula A y 1,40 (IC95%: –2,65;5,46) con la molécula B frente a la molécula O (latidos/min). Las diferencias en el cambio de presión arterial media fueron de 1 (IC95%: –4,81;6,81) para la molécula A y de 1,82 (IC95%: –4,08;7,74) para la molécula B frente a la molécula O (mmHg). Hubo un caso de hipotensión arterial en cada grupo.ConclusiónLos resultados sugieren que desde un punto de vista farmacodinámico las moléculas innovadora y genéricas de remifentanilo son similares para la laringoscopia/intubación con dosis TCI de 6, 8 y 10ng/ml.AbstractIntroductionSeveral remifentanil products are commercialized in Colombia while these have never been compared in a clinical setting.ObjectiveThe aim of this study was to investigate the pharmacodynamic profile of the branded molecule of remifentanil (group O: Glaxo SmithKline Manufacturing S.P.A.) and two unbranded molecules (group A: Laboratorios Chalver de Colombia S.A. and group B: Instituto Biológico Contemporaneo, Argentina) registered in Colombia.MethodsWe carried out a double-blind, randomized, controlled trial. The branded molecule of remifentanil (group O, n=29) was compared with the two unbranded molecules (group A, n=29; group B, n=32) during anesthetic induction and tracheal intubation in adult patients ASAI without predictors for difficult airway. The target controlled infusion (TCI) doses evaluated were 6, 8 and 10ng/ml with the Minto model. Induction was complemented with propofol 5mcg/ml (TCI) with the Schneider model and rocuronium 0.6mg/kg. The primary outcome was defined as the difference in mean arterial pressure and heart rate pre-intubation (TCI equilibrium) and post-intubation (maximum measurement within 5minutes).ResultsA similar pharmacodinamic profile was observed between the studied remifentanil molecules. The differences in the change in heart rate were 1.27 (95% CI: –3.11;5.67) with molecule A and 1.40 (95%CI: –2.65;5.46) with molecule B against molecule O (beats/minute). The differences in the change in mean arterial pressure were 1 (95%CI: –4.81;6.81) for molecule A and 1.82 (95%CI: –4.08;7.74) for molecule B against molecule O (mmHg). There was a case of arterial hypotension in each group.ConclusionThe results suggest that from a pharmacodynamic point of view branded and unbranded remifentanil molecules are similar for laryngoscopy/intubation with TCI doses 6, 8 and 10ng/ml

Surface Screening in the Casimir Force

We calculate the corrections to the Casimir force between two metals due to the spatial dispersion of their response functions. We employ model-independent expressions for the force in terms of the optical coefficients. We express the non-local corrections to the Fresnel coefficients employing the surface $d_\perp$ parameter, which accounts for the distribution of the surface screening charge. Within a self-consistent jellium calculation, spatial dispersion increases the Casimir force significatively for small separations. The nonlocal correction has the opposite sign than previously predicted employing hydrodynamic models and assuming abruptly terminated surfaces.Comment: 5 pages, 2 figure

Functional Diversity of Small and Large Trees Along Secondary Succession in a Tropical Dry Forest

Functional Diversity is considered an important driver of community assembly in environmental and successional gradients. To understand tree assembly processes in a semideciduous tropical forest, we analyzed the variation of Functional Richness (FRic), Functional Divergence (FDiv), and Functional Evenness (FEve) of small vs. large trees in relation to fallow age after slash-and-burn agriculture and topographical position (flat sites vs. hills). FRic of small trees was lower than null model predicted values across the successional gradient, and decreased unexpectedly in older successional ages. FRic of large trees was higher than null model predictions early in succession and lower in late-successional stands on hills. Dominant species were more similar (low FDiv) in early and intermediate successional stands for small trees, and on hills for large trees, suggesting that species that are best adapted to harsh conditions share similar traits. We also found evidence of competitive exclusion among similar species (high FEve) for small trees in early successional stands. Overall, our results indicate that community assembly of small trees is strongly affected by the changing biotic and abiotic conditions along the successional and topographical gradient. For large trees, hills may represent the most stressful conditions in this landscape