818 research outputs found
Enzymatic hydrolysis of esters from 2-carboxy-6- methoxy-2,3-dihydrobenzofuran acid
In this work we describe the results of the enzymatic hydrolysis of esters from 2-carboxy-6-methoxy-2,3-dihydrobenzofuran acid using Candida antarctica lipase supported on acrylic resin, with enantiomeric excesses ranging between 80 to 99%
Epidemiología de las fracturas de la extremidad proximal del fémur en asturias
Hemos realizado un estudio epidemiológico de las fracturas de fémur proximal
en personas mayores de 50 años, atendidas en nuestro Hospital durante los años 1990-92.
Se valoraron un total de 355 casos. En el período estudiado se observó que las fracturas más
numerosas fueron la cervicales, no encontrando diferencias significativas en los ingresos según
el período estacional. La edad media de presentación fue de 81 años. La tasa de incidencia
fue muy semejante a las otras provincias españolas y menor que la encontrada en los países
del Norte de Europa, Inglaterra y Estados Unidos.We have performed an epidemiologic study on the incidence of proximal femoral
fractures in patients older than 50 years, all reviewed in our Hospital from 1990 to 1992.
We included 355 patients. Femoral neek fractures were the most frequent lesions. No significant
differences in the hospital admissions were found during all the year's seasons. The mean
age of presentation was 81 years. The incidence rate was similar to the rest of Spain, and less
than in North Europe, England and United States
Autofluorescence endoscopic spectro-imaging and 2D-cartography for in situ localisation and diagnosis of cancerous lesions
Early diagnosis is the most efficient way to struggle against cancer. Among all the existing techniques, optical methods
(photodiagnosis from NUV to NIR) show important characteristics required by the physicians : high sensitivity, non-ionising radiations and non-traumatic measurements. They are particularly well suited to the detection of cancers
in hollow organs, that are usually superficial and hardly visible with classical endoscopy. This paper describes a
methodological approach based on the use of tissue autofluorescence, applicable in clinical endoscopy, and leading to
the definition of diagnosis indicators from the spectral parameters. Following a state-of-the-art on autofluorescence
spectroscopic (LIFS) and endoscopic imaging methods, we present the efficiency of fibered LIFS in terms of sensitivity
and specificity for the diagnosis of esophagus cancerous lesions (clinical study over 25 patients). We then present the
technological characteristics of an autofluorescence endoscopic imaging prototype developed in our labs as well as its
calibration. A second part is devoted to endoscopic image registration and mosaicing and to optics aberration
correction in perspective of the automatic construction of a panoramic image (cartography) of the organ’s explored
areas. Finally, exploiting the fluorescence data provided by the imager, the feasibility of the superimposition of spatial
and spectral information is validated with a phantom.Le diagnostic précoce est le moyen le plus efficace de lutte contre le cancer. Parmi toutes les techniques
possibles, les méthodes optiques (photodiagnostic du proche UV au proche IR) présentent des caractéristiques
importantes recherchées par les médecins : grande sensibilité, radiations non ionisantes et mesures
atraumatiques. Elles sont particulièrement bien adaptées à la détection des cancers des organes creux, par
nature superficiels et difficilement décelables en endoscopie classique. Cet article décrit une approche
méthodologique fondée sur l’exploitation de l’autofluorescence tissulaire, applicable en endoscopie clinique, et
conduisant à l’élaboration d’indicateurs diagnostiques issus des paramètres spectraux. Après un état de l’art
sur les méthodes spectroscopiques (LIFS) et d’imagerie endoscopique d’autofluorescence, nous montrons
l’efficacité de la LIFS fibrée en terme de sensibilité et de spécificité pour le diagnostic de lésions cancéreuses
de l’oesophage (étude clinique sur 25 patients). Nous présentons ensuite les caractéristiques technologiques
et le calibrage du prototype d’imageur endoscopique d’autofluorescence développé. Une seconde partie traite
du pré-traitement, du recalage et du mosaïquage des images endoscopiques appliqués à la construction
automatique d’une image panoramique (cartographie) à partir de séquences vidéos des zones explorées de
l’organe. Finalement, en exploitant les informations de fluorescence fournies par l’imageur,
la faisabilité d’une superposition des informations spatiale et spectrale est validée sur fantôme
Intravenous ascorbic acid to prevent and treat cancer-associated sepsis?
The history of ascorbic acid (AA) and cancer has been marked with controversy. Clinical studies evaluating AA in cancer outcome continue to the present day. However, the wealth of data suggesting that AA may be highly beneficial in addressing cancer-associated inflammation, particularly progression to systemic inflammatory response syndrome (SIRS) and multi organ failure (MOF), has been largely overlooked. Patients with advanced cancer are generally deficient in AA. Once these patients develop septic symptoms, a further decrease in ascorbic acid levels occurs. Given the known role of ascorbate in: a) maintaining endothelial and suppression of inflammatory markers; b) protection from sepsis in animal models; and c) direct antineoplastic effects, we propose the use of ascorbate as an adjuvant to existing modalities in the treatment and prevention of cancer-associated sepsis
The 2HWC HAWC Observatory Gamma Ray Catalog
We present the first catalog of TeV gamma-ray sources realized with the
recently completed High Altitude Water Cherenkov Observatory (HAWC). It is the
most sensitive wide field-of-view TeV telescope currently in operation, with a
1-year survey sensitivity of ~5-10% of the flux of the Crab Nebula. With an
instantaneous field of view >1.5 sr and >90% duty cycle, it continuously
surveys and monitors the sky for gamma ray energies between hundreds GeV and
tens of TeV.
HAWC is located in Mexico at a latitude of 19 degree North and was completed
in March 2015. Here, we present the 2HWC catalog, which is the result of the
first source search realized with the complete HAWC detector. Realized with 507
days of data and represents the most sensitive TeV survey to date for such a
large fraction of the sky. A total of 39 sources were detected, with an
expected contamination of 0.5 due to background fluctuation. Out of these
sources, 16 are more than one degree away from any previously reported TeV
source. The source list, including the position measurement, spectrum
measurement, and uncertainties, is reported. Seven of the detected sources may
be associated with pulsar wind nebulae, two with supernova remnants, two with
blazars, and the remaining 23 have no firm identification yet.Comment: Submitted 2017/02/09 to the Astrophysical Journa
Observation of the Crab Nebula with the HAWC Gamma-Ray Observatory
The Crab Nebula is the brightest TeV gamma-ray source in the sky and has been
used for the past 25 years as a reference source in TeV astronomy, for
calibration and verification of new TeV instruments. The High Altitude Water
Cherenkov Observatory (HAWC), completed in early 2015, has been used to observe
the Crab Nebula at high significance across nearly the full spectrum of
energies to which HAWC is sensitive. HAWC is unique for its wide field-of-view,
nearly 2 sr at any instant, and its high-energy reach, up to 100 TeV. HAWC's
sensitivity improves with the gamma-ray energy. Above 1 TeV the
sensitivity is driven by the best background rejection and angular resolution
ever achieved for a wide-field ground array.
We present a time-integrated analysis of the Crab using 507 live days of HAWC
data from 2014 November to 2016 June. The spectrum of the Crab is fit to a
function of the form . The data is well-fit with values of
, , and
log when
is fixed at 7 TeV and the fit applies between 1 and 37 TeV. Study of the
systematic errors in this HAWC measurement is discussed and estimated to be
50\% in the photon flux between 1 and 37 TeV.
Confirmation of the Crab flux serves to establish the HAWC instrument's
sensitivity for surveys of the sky. The HAWC survey will exceed sensitivity of
current-generation observatories and open a new view of 2/3 of the sky above 10
TeV.Comment: Submitted 2017/01/06 to the Astrophysical Journa
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Xanthohumol lowers body weight and fasting plasma glucose in obese male Zucker fa/fa rats
Obesity contributes to increased risk for several chronic diseases including cardiovascular disease and type 2 diabetes. Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus), was tested for efficacy on biomarkers of metabolic syndrome in 4 week old Zucker fa/fa rats, a rodent model of obesity. Rats received daily oral doses of xanthohumol at 0, 1.86, 5.64, and 16.9 mg/kg BW for 6 weeks. All rats were maintained on a high fat (60% kcal) AIN-93G diet for 3 weeks to induce severe obesity followed by a normal AIN-93G (15% kcal fat) diet for the last 3 weeks of the study. Weekly food intake and body weight were recorded. Plasma cholesterol, glucose, insulin, triglyceride, and monocyte chemoattractant protein -1 (MCP-1) levels were assessed using commercial assay kits. Plasma and liver tissue levels of XN and its metabolites were determined by liquid-chromatography tandem mass spectrometry. Plasma and liver tissue levels of xanthohumol were similar between low and medium dose groups and significantly (p<0.05) elevated in the highest dose group. There was a dose-dependent effect on body weight and plasma glucose levels. The highest dose group (n=6) had significantly lower plasma glucose levels compared to the control group (n=6) in male but not female rats. There was also a significant decrease in body weight for male rats in the highest dose group (16.9 mg / kg BW) compared to rats that received no xanthohumol, which was also not seen for female rats. Plasma cholesterol, insulin, triglycerides, and MCP-1 as well as food intake were not affected by treatment. The findings suggest that xanthohumol has beneficial effects on markers of metabolic syndrome.Keywords: Humulus lupulus, Hops, Obesity, Type 2 diabetes, Xanthohumol, Rats, Metabolic syndromeKeywords: Humulus lupulus, Hops, Obesity, Type 2 diabetes, Xanthohumol, Rats, Metabolic syndrom
All-particle cosmic ray energy spectrum measured by the HAWC experiment from 10 to 500 TeV
We report on the measurement of the all-particle cosmic ray energy spectrum
with the High Altitude Water Cherenkov (HAWC) Observatory in the energy range
10 to 500 TeV. HAWC is a ground based air-shower array deployed on the slopes
of Volcan Sierra Negra in the state of Puebla, Mexico, and is sensitive to
gamma rays and cosmic rays at TeV energies. The data used in this work were
taken from 234 days between June 2016 to February 2017. The primary cosmic-ray
energy is determined with a maximum likelihood approach using the particle
density as a function of distance to the shower core. Introducing quality cuts
to isolate events with shower cores landing on the array, the reconstructed
energy distribution is unfolded iteratively. The measured all-particle spectrum
is consistent with a broken power law with an index of prior to
a break at ) TeV, followed by an index of . The
spectrum also respresents a single measurement that spans the energy range
between direct detection and ground based experiments. As a verification of the
detector response, the energy scale and angular resolution are validated by
observation of the cosmic ray Moon shadow's dependence on energy.Comment: 16 pages, 11 figures, 4 tables, submission to Physical Review
Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC
We present results from daily monitoring of gamma rays in the energy range
to TeV with the first 17 months of data from the High
Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2
steradians and duty cycle of % are unique features compared to other TeV
observatories that allow us to observe every source that transits over HAWC for
up to hours each sidereal day. This regular sampling yields
unprecedented light curves from unbiased measurements that are independent of
seasons or weather conditions. For the Crab Nebula as a reference source we
find no variability in the TeV band. Our main focus is the study of the TeV
blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a
power law index and
an exponential cut-off
TeV. For Mrk 501, we find an index and exponential cut-off TeV. The light curves for both sources show clear
variability and a Bayesian analysis is applied to identify changes between flux
states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab
Nebula flux by a factor of approximately five. For Mrk 501, several transits
show fluxes in excess of three times the Crab Nebula flux. In a comparison to
lower energy gamma-ray and X-ray monitoring data with comparable sampling we
cannot identify clear counterparts for the most significant flaring features
observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical
Journa
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