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1.
Artículo en Inglés | MEDLINE | ID: mdl-36429910

RESUMEN

Many industrial sectors still lack automation resources to optimize their production processes, aiming to make manufacturing leaner and offer better working conditions to operators. Without these improvements, workers can suffer physical and even psychological damage from the ergonomic risks of the activities performed. Thus, the aim of this paper is to present the ergonomic evaluation of packaging tapes workstation before and after the implementation of an automatic packaging machine, called Guzzetti. In the Guzzetti context, the paper shows the implementation of an electrical system based on controlling a mechanical device powered by servomotors and controlled by a PLC is necessary. For ergonomic evaluation, the paper presents the application of three methods: Suzanne Rodger, Strain Index, called Moore and Garg and REBA (Rapid Entire Body Assessment). With the results collection, was possible to obtain improvements in ergonomic risks that changed from the intermediate level to low level in all methods.


Asunto(s)
Ergonomía , Embalaje de Productos , Humanos , Ergonomía/métodos
2.
West Afr J Med ; 38(3): 223-240, 2021 03 22.
Artículo en Inglés | MEDLINE | ID: mdl-33765371

RESUMEN

BACKGROUND: Hypertension is the commonest cardiovascular risk factor globally and is a cause of untold morbidity and mortality. However, its clinical correlates at the community level have not been well elucidated. METHODS: History taking, anthropometric measurements, electrocardiograms and laboratory investigations were done for all the study subjects. Ethical approval was obtained from the institution's ethical body. Analysis was done using SPSS version 20. Two hundred people were recruited for the study. The prevalence of hypertension in the community was 58.5% with 31(15.5%) being newly diagnosed. The Body Mass Index [BMI] (28.2±6vs 25.6±5.3; P=0.003),Waist-Hip ratio (0.9±0.08 vs 0.86±0.06; p= 0.001), total cholesterol (5.675±1.8 vs 4.6±1.7, P=0.000), triglycerides (1.19±0.85 vs 0.91±0.59; p=0.019), LDL cholesterol (3.38±1.6 vs 2.66±1.5; p=0.002), heart rate (82.4±15.8 vs 76.8±11.2; p=0.018) QRS duration (84.8±13.4 vs 80.5±11.2; p=0.040), and QTc (0.423±0.041 vs 0.402±0.035; p=0.001) were higher in those with hypertension. NYHA functional class was worse in hypertensives (p=0.041). Prevalence of left ventricular hypertrophy (LVH) in hypertensives ranged from 2.6 to 48.2%, depending on the criteria used. Systolic blood pressure, pulse pressures, HDL levels and hip circumferences were higher in those with electrocardiographic LVH. Systolic blood pressure (OR:1.045, P=0.006; CI: 1.013-1.079) and a normal BMI (OR: 0.159, p= 0.004; CI: 0.045-0.559) were the independent predictors of LVH in this study. CONCLUSION: The prevalence of hypertension is rising, even in rural populations, with accompanying LVH, higher QTc and florid cardiovascular risk factors. It is therefore imperative to tighten the reins of control of blood pressure and other cardiovascular risk factors before the cardiovascular morbidity and mortality explode in the rural communities.


CONTEXTE: L'hypertension est le facteur de risque cardiovasculaire le plus courant dans le monde et est une cause de morbidité et de mortalité indicibles. Cependant, ses corrélats cliniques au niveau communautaire n'ont pas été bien élucidés. MÉTHODES: Des antécédents, des mesures anthropométriques, des électrocardiogrammes et des examens de laboratoire ont été effectués pour tous les sujets de l'étude. L'approbation éthique a été obtenue de l'organe déontologique de l'institution. L'analyse a été effectuée à l'aide de la version 20 de SPSS. Deux cents personnes ont été recrutées pour l'étude. La prévalence de l'hypertension dans la communauté était de 58,5%, 31 (15,5%) nouvellement diagnostiqués. L'indice de masse corporelle [IMC] (28,2 ± 6 vs 25,6 ± 5,3; P = 0,003), le rapport taille-hanches (0,9 ± 0,08 vs 0,86 ± 0,06; p = 0,001), le cholestérol total (5,675 ± 1,8 vs 4,6 ± 1,7, P = 0,000), triglycérides (1,19 ± 0,85 vs 0,91 ± 0,59; p = 0,019), cholestérol LDL (3,38 ± 1,6 vs 2,66 ± 1,5; p = 0,002), fréquence cardiaque (82,4 ± 15,8 vs 76,8 ± 11,2; p = 0,018) Durée du QRS (84,8 ± 13,4 vs 80,5 ± 11,2; p = 0,040) et l'intervalle QTc (0,423 ± 0,041 vs 0,402 ± 0,035; p = 0,001) étaient plus élevés chez les personnes souffrant d'hypertension. La classe fonctionnelle NYHA était pire chez les hypertendus (p = 0,041). La prévalence de l'hypertrophie ventriculaire gauche (LVH) chez les hypertendus variait de 2,6 à 48,2%, selon la critères utilisés. La pression artérielle systolique, les pressions de pouls, les taux de HDL et la circonférence de la hanche étaient plus élevés chez les personnes atteintes de LVH électrocardiographique. La pression artérielle systolique (OR: 1,045, P = 0,006; IC: 1,013­1,079) et un IMC normal (OR: 0,159, p = 0,004; IC: 0,045­0,559) étaient les prédicteurs indépendants de l'HGV dans cette étude. CONCLUSION: La prévalence de l'hypertension est en hausse, même dans les populations rurales, accompagnée de LVH, d'un QTc plus élevé et de facteurs de risque cardiovasculaires florissants. Il est donc impératif de resserrer les rênes du contrôle de la pression artérielle et des autres facteurs de risque cardiovasculaire avant que la morbidité et la mortalité cardiovasculaires n'explosent dans les communautés rurales. Mots clés: Hypertension, hypertrophie ventriculaire gauche, indice de masse corporelle, HDL.


Asunto(s)
Hipertensión , Población Rural , Presión Sanguínea , Humanos , Hipertensión/epidemiología , Hipertrofia Ventricular Izquierda/epidemiología , Anamnesis , Nigeria/epidemiología , Prevalencia , Factores de Riesgo
3.
West Afr J Med ; 37(7): 750-756, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33296483

RESUMEN

BACKGROUND: Obstructive sleep apnoea (OSA) is a common medical condition which has long been recognized as a major contributor to morbidity and mortality in developed countries but that remains underdiagnosed, particularly in rural communities. This study aimed to assess the prevalence of adults who have a high risk of obstructive sleep apnoea in a sample of adults living in Ejigbo, a rural community in south western Nigeria. METHODS: This was a community-based cross-sectional descriptive study done to assess the prevalence of high risk of obstructive sleep apnoea in adult residents of the community using the STOP-BANG questionnaire. Data collected include socio-demographic characteristics, anthropometric measurements and blood pressure. A blood sample was also taken for lipid profile. Factors associated with a high risk of obstructive sleep apnoea were identified. RESULTS: The study involved 257 participants out of which 88 (34.2%) had a high risk of OSA. Risk of obstructive sleep apnoea was significantly associated with male sex (p<0.001), age (p<0.001), body mass index (BMI) (p=0.001), neck circumference (p<0.001), cigarette smoking (p=0.039) and low density lipoprotein (p=0.043). CONCLUSION: Obstructive sleep apnoea is relatively common in the study area. This calls for urgent preventive measures to stem the tide and mitigate the associated morbidity and mortality.


Asunto(s)
Población Rural , Apnea Obstructiva del Sueño , Adulto , Índice de Masa Corporal , Estudios Transversales , Femenino , Humanos , Masculino , Nigeria/epidemiología , Factores de Riesgo , Apnea Obstructiva del Sueño/epidemiología
4.
Biomolecules ; 10(3)2020 02 27.
Artículo en Inglés | MEDLINE | ID: mdl-32120912

RESUMEN

The successful production of a biosurfactant is dependent on the development of processes using low cost raw materials. In the present work, an economically attractive medium composed of corn steep liquor and waste cooking oil was formulated to maximize the production of bioemulsifier by Mucor circinelloides UCP0001. A central rotational composite design was applied to statistical validation of the production. The emulsifying properties, stability under extreme conditions, its toxicity character, and the characterization of the bioemulsifier were determined. The best condition for biomolecule synthesis occurred in the assay 2 containing 4% of corn steep liquor and 3% waste soybean oil and exhibited 100% emulsification index for canola oil and petroleum, as well as excellent emulsifying activity for canola oil and burned engine oil. The nutritional factors studied showed statistical relevance, since all linear, quadratic effects and their interactions were significant. The bioemulsifier showed 2.69 g/L yield and the chemical character of the molecule structure was identified by FT-IR (Fourier Transform Infrared) spectroscopy. The bioemulsifier showed no toxicity to Artemia salina and Chlorella vulgaris. Stable emulsions were obtained under extreme conditions of temperature, pH, and salinity. These findings contribute to understanding of the relationship between production, physical properties, chemical composition, and stability of bioemulsifier for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.


Asunto(s)
Emulsionantes/metabolismo , Microbiología Industrial , Mucor/metabolismo , Biodegradación Ambiental , Biotransformación
5.
Chemosphere ; 202: 686-693, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29602101

RESUMEN

Composted urban biowaste-derived substances (BBS-GC) are used as carbon sources for the preparation of carbon-coated magnet-sensitive nanoparticles obtained via co-precipitation method and the subsequent thermal treatment at 550 °C under nitrogen atmosphere. A multitechnique approach has been applied to investigate the morphology, magnetic properties, phase composition, thermal stability of the obtained magnet-sensitive materials. In particular, pyrolysis-induced modifications affecting the BBS-GC/carbon shell were highlighted. The adsorption capacity of such bio-derivative magnetic materials for the removal of hydrophobic contaminants such as polycyclic aromatic hydrocarbons was evaluated in order to verify their potential application in wastewater remediation process. The promising results suggest their use as a new generation of magnet-responsive easily-recoverable adsorbents for water purification treatments.


Asunto(s)
Imanes/química , Hidrocarburos Policíclicos Aromáticos/aislamiento & purificación , Eliminación de Residuos/métodos , Administración de Residuos/métodos , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Hidrocarburos Policíclicos Aromáticos/química , Contaminantes Químicos del Agua/química
6.
Ecol Evol ; 8(24): 12559-12575, 2018 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30619565

RESUMEN

The diverse offspring of clonal species differ in their dispersability, influencing genotypic diversity and clonal structure. Here, we determined dispersal patterns and their impact on genetic structure in Opuntia microdasys, a self-incompatible cactus with three dispersal units (one sexual and two clonal). We analyzed dispersal, using experiments at three populations, and assessed multilocus genotypes (ISSR markers) of all individuals in 10 clumps per population with known reproductive origin (sexual or clonal). Genotype of all samples, population structure, and migration between clumps and populations were assessed with GenAlEx and GenoDive, assuming higher genotypic diversity and migration when sexual reproduction is more frequent. We determined the most likely number of genetic clusters with STRUCTURE and geneland. Dispersal differed among populations; primary dispersal occurred at short distances and was farthest on steep slopes, and dispersal distance increased after secondary dispersal. Clumps had 116 different multilocus genotypes in three spatially explicit genetic clusters. We detected genetic structure at small scale, genotypic diversity among clumps varied between populations; diversity decreased while clonal dominance increased, and the most variation occurred among clumps. Genetic structure was moderate, suggesting gene flow by seed dispersal allows slight differentiation among population at large scales. Genetic diversity within clumps was the lowest because dispersal of clonal propagules was limited and caused genotypic dominance at local scale. However, the combined dispersal pattern of sexual and clonal dispersal units is fine-tuned by environmental factors, generating a range of genetic diversity among clusters and populations. This pattern suggests that genetic structure of clonal plants is more dynamic than thought, and dispersal of different types of offspring affects genetic structure at many scales.

7.
Int J Tuberc Lung Dis ; 17(3): 345-7, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23321341

RESUMEN

We measured quality of life (QOL) among individuals receiving treatment for human immunodeficiency virus (HIV; n = 45), active tuberculosis (TB; n = 44) and both TB and HIV (n = 9) in Rio de Janeiro, Brazil. Active treated TB was associated with lower physical health (absolute decrease of 0.95 standard deviation in summary score), but not mental health, among people being treated for HIV. Visual analogue scale scores were similar across all three populations, and corresponded closely to standard disability weights used in the literature. Among patients receiving treatment, those with HIV, active TB and both conditions together appear to have similar QOL.


Asunto(s)
Fármacos Anti-VIH/uso terapéutico , Antituberculosos/uso terapéutico , Coinfección , Infecciones por VIH/tratamiento farmacológico , Calidad de Vida , Tuberculosis/tratamiento farmacológico , Adulto , Análisis de Varianza , Brasil , Estudios Transversales , Evaluación de la Discapacidad , Femenino , Infecciones por VIH/diagnóstico , Infecciones por VIH/psicología , Encuestas de Atención de la Salud , Estado de Salud , Humanos , Modelos Lineales , Masculino , Salud Mental , Encuestas y Cuestionarios , Resultado del Tratamiento , Tuberculosis/diagnóstico , Tuberculosis/psicología , Salud Urbana
8.
Nature ; 476(7361): 421-4, 2011 Aug 24.
Artículo en Inglés | MEDLINE | ID: mdl-21866154

RESUMEN

Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

9.
Clin Transplant ; 25(1): 77-82, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-20070320

RESUMEN

Multidetector computed tomography (MDCT) angiography is a reliable technique for assessing pre-operative renal anatomy in living kidney donors. The method has largely evolved into protocols that eliminate dedicated venous phase and instead utilize a combined arterial/venous phase to delineate arterial and venous anatomy simultaneously. Despite adoption of this protocol, there has been no study to assess its accuracy. To assess whether or not MDCT angiography compares favorably to intra-operative findings, 102 donors underwent MDCT angiography without a dedicated venous phase with surgical interpretation of renal anatomy. Anatomical variants included multiple arteries (12%), multiple veins (7%), early arterial bifurcation (13%), late venous confluence (5%), circumaortic renal veins (5%), retroaortic vein (1%), and ureteral duplication (2%). The sensitivity and specificity of multiple arterial anomalies were 100% and 97%, respectively. The sensitivity and specificity of multiple venous anomalies were 92% and 98%, respectively. The most common discrepancy was noted exclusively in the interpretation of right venous anatomy as it pertained to the renal vein/vena cava confluence (3%). MDCT angiography using a combined arterial/venous contrast-enhanced phase provides suitable depiction of renal donor anatomy. Careful consideration should be given when planning a right donor nephrectomy whether the radiographic interpretation is suggestive of a late confluence.


Asunto(s)
Angiografía/métodos , Supervivencia de Injerto , Trasplante de Riñón/diagnóstico por imagen , Donadores Vivos , Arteria Renal/diagnóstico por imagen , Venas Renales/diagnóstico por imagen , Tomografía Computarizada por Rayos X , Humanos , Cuidados Preoperatorios , Pronóstico , Arteria Renal/anatomía & histología , Venas Renales/anatomía & histología , Sensibilidad y Especificidad
10.
Science ; 330(6006): 944-6, 2010 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-20947727

RESUMEN

Soft gamma repeaters (SGRs) and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, that is, neutron stars powered by extreme magnetic fields, B ~ 10(14) to 10(15) gauss. We report on a soft gamma repeater with low magnetic field, SGR 0418+5729, recently detected after it emitted bursts similar to those of magnetars. X-ray observations show that its dipolar magnetic field cannot be greater than 7.5 × 10(12) gauss, well in the range of ordinary radio pulsars, implying that a high surface dipolar magnetic field is not necessarily required for magnetar-like activity. The magnetar population may thus include objects with a wider range of B-field strengths, ages, and evolutionary stages than observed so far.

11.
BMC Public Health ; 10: 173, 2010 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-20353567

RESUMEN

BACKGROUND: Delays seeking care worsen the burden of tuberculosis and cost of care for patients, families and the public health system. This study investigates costs of tuberculosis diagnosis incurred by patients, escorts and the public health system in 10 districts of Ethiopia. METHODS: New pulmonary tuberculosis patients > or = 15 years old were interviewed regarding their health care seeking behaviour at the time of diagnosis. Using a structured questionnaire patients were interviewed about the duration of delay at alternative care providers and the public health system prior to diagnosis. Costs incurred by patients, escorts and the public health system were quantified through patient interview and review of medical records. RESULTS: Interviews were held with 537 (58%) smear positive patients and 387 (42%) smear negative pulmonary patients. Of these, 413 (45%) were female; 451 (49%) were rural residents; and the median age was 34 years. The mean (median) days elapsed for consultation at alternative care providers and public health facilities prior to tuberculosis diagnosis was 5 days (0 days) and 3 (3 days) respectively. The total median cost incurred from first consultation to diagnosis was $27 per patient (mean = $59). The median costs per patient incurred by patient, escort and the public health system were $16 (mean = $29), $3 (mean = $23) and $3 (mean = $7) respectively. The total cost per patient diagnosed was higher for women, rural residents; those who received government food for work support, patients with smear negative pulmonary tuberculosis and patients who were not screened for TB in at least one district diagnostic centers. CONCLUSIONS: The costs of tuberculosis diagnosis incurred by patients and escorts represent a significant portion of their monthly income. The costs arising from time lost in seeking care comprised a major portion of the total cost of diagnosis, and may worsen the economic position of patients and their families. Getting treatment from alternative sources and low index of suspicion public health providers were key problems contributing to increased cost of tuberculosis diagnosis. Thus, the institution of effective systems of referral, ensuring screening of suspects across the district public health system and the involvement of alternative care providers in district tuberculosis control can reduce delays and the financial burden to patients and escorts.


Asunto(s)
Costos de la Atención en Salud/estadística & datos numéricos , Accesibilidad a los Servicios de Salud/economía , Tuberculosis Pulmonar/diagnóstico , Tuberculosis Pulmonar/economía , Adolescente , Adulto , Anciano , Etiopía/epidemiología , Femenino , Humanos , Entrevistas como Asunto , Masculino , Registros Médicos , Persona de Mediana Edad , Salud Pública/economía , Características de la Residencia , Factores Socioeconómicos , Esputo/microbiología , Encuestas y Cuestionarios , Factores de Tiempo , Viaje/economía , Tuberculosis Pulmonar/epidemiología
12.
Cir. plást. ibero-latinoam ; 36(1): 19-24, ene.-mar. 2010. tab, ilus
Artículo en Español | IBECS | ID: ibc-85579

RESUMEN

La ginecomastia es la anomalía mamaria más frecuente en el sexo masculino. La pseudoginecomastia es un cuadro que a menudo se confunde con la ginecomastia y consiste en el aumento de tejido graso en la región pectoral. El equipo de Cirugía Plástica del Hospital Militar de Santiago (Chile), por atender una población de jóvenes que realizan el servicio militar obligatorio, ha tenido una gran experiencia en el manejo de esta enfermedad; es por esto que nos planteamos como objetivo de estudio evaluar el manejo de los pacientes operados por esta patología en el Hospital Militar y la Clínica Santa María de Santiago, e intentar ofrecer pautas para el manejo de esta patología de la Cirugía General a nivel nacional. Realizamos un estudio retrospectivo y descriptivo sobre 106pacientes operados con diagnóstico de ginecomastia o pseudoginecomastia entre Enero de 1987 y Julio de 2005 en las instituciones antes mencionadas. El promedio de edad de los pacientes incluidos en el estudio fue de 24 años (rango: 15 a 50 años): 32% por ginecomastia pura,29,4% por pseudoginecomastia y 38,8% por ambas. Todos fueron grado I y II a de la clasificación de Simon. En el 50% de los casos se realizó adenectomía más lipoaspiración; adenectomía sola en 26,4%y lipoaspiración exclusiva en 23,6%. Casos complicados, 3,8% con hematomas y equimosis. La ginecomastia es una enfermedad frecuente en la adolescenciaque además de provocar alteraciones estéticas, provoca alteraciones psicológicas en el paciente. La liposucción se consagra como una técnica quirúrgica importante para el tratamiento quirúrgico de esta anormalidad (AU)


Gynecomastia is common among men. Pseudogynecomastia, caused by an increased subcutaneous fat in the mammary area, can be confused with gynecomastia. We report our experience with the surgical treatment of both making a review of medical records of106 patients, aged 15 to 50 years, operated at the Plastic Surgery Unit of the Military Hospital and Clínica Santa María in Santiago(Chile).Thirty two percent of patients had a pure gynecomastia, 29, 4%had pseudogynecomastia, and 38,8% had both conditions. All were mild or moderate. A mastectomy plus liposuction was performed in 50% of patients, solely mastectomy in 26,4% and solely liposuction in 26,4%. There were surgical complications in 3,8%such as hematomas or echymoses. As a conclusion: Ginecomastia is a frequent pathology in young men that can produce aesthetic and psychological pathologies. Surgical treatment requires liposuction in most patients to achieve a good result (AU)


Asunto(s)
Humanos , Masculino , Ginecomastia/cirugía , Mamoplastia/métodos , Lipectomía/métodos , Complicaciones Intraoperatorias/epidemiología , Estudios Retrospectivos , Tejido Adiposo/cirugía
13.
Nature ; 461(7268): 1258-60, 2009 Oct 29.
Artículo en Inglés | MEDLINE | ID: mdl-19865166

RESUMEN

Gamma-ray bursts (GRBs) are produced by rare types of massive stellar explosion. Their rapidly fading afterglows are often bright enough at optical wavelengths that they are detectable at cosmological distances. Hitherto, the highest known redshift for a GRB was z = 6.7 (ref. 1), for GRB 080913, and for a galaxy was z = 6.96 (ref. 2). Here we report observations of GRB 090423 and the near-infrared spectroscopic measurement of its redshift, z = 8.1(-0.3)(+0.1). This burst happened when the Universe was only about 4 per cent of its current age. Its properties are similar to those of GRBs observed at low/intermediate redshifts, suggesting that the mechanisms and progenitors that gave rise to this burst about 600,000,000 years after the Big Bang are not markedly different from those producing GRBs about 10,000,000,000 years later.

14.
Talanta ; 80(2): 489-92, 2009 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-19836509

RESUMEN

A method for the determination of oleic acid in sunflower seeds is proposed. One hundred samples of sunflower seeds were analyzed by near-infrared diffuse reflectance spectroscopy (NIRDRS). The direct measures were realized in ground and sifted seeds. The PLS multivariate calibration model was obtained using first derivate absorbance values as response matrix, while the oleic acid concentration matrix was obtained analyzing the seed samples by gas chromatography with a flame ionization detector (GC-FID). The NIRDRS-PLS model was validated externally using unknown samples of sunflower seeds. The accuracy and precision of the method was evaluated using GC as reference method. The following figures of merit (FOM) were obtained: LOD=3.4% (w/w); LOQ=11.3% (w/w); SEN=8x10(-5); SEL=0.15; analytical sensibility (gamma)=1.5 and linear range (LR)=18.1-89.2% (w/w). This method is useful for the fast determination of oleic acid in sunflower seeds and for quality control of raw materials.


Asunto(s)
Helianthus/química , Ácido Oléico/análisis , Semillas/química , Espectroscopía Infrarroja Corta/métodos , Algoritmos , Calibración , Cromatografía de Gases , Análisis Multivariante , Ácido Oléico/química , Ácido Oléico/normas , Control de Calidad , Reproducibilidad de los Resultados
15.
Science ; 325(5945): 1222-3, 2009 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-19729650

RESUMEN

White dwarfs typically have masses in a narrow range centered at about 0.6 solar mass (M(o)). Only a few ultramassive white dwarfs (mass > 1.2 M(o)) are known. Those in binary systems are of particular interest, because a small amount of accreted mass could drive them above the Chandrasekhar limit, beyond which they become gravitationally unstable. Using data from the x-ray multimirror mission (XMM)-Newton satellite, we show that the x-ray pulsator RX J0648.0-4418 is a white dwarf with mass > 1.2 M(o), based on dynamical measurements only. This ultramassive white dwarf in a post-common envelope binary with a hot subdwarf can reach the Chandrasekhar limit, and possibly explode as a type Ia supernova, when its helium-rich companion will transfer mass at an increased rate through Roche lobe overflow.

16.
Ophthalmic Epidemiol ; 13(3): 173-81, 2006 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-16854771

RESUMEN

AIM: Trachoma is a public health problem in Ethiopia accounting for 35-50% of cases of blindness. This study aims to determine the prevalence of trachoma in Tigray and to evaluate whether common risk factors are also risk factors in this region. METHOD: A cross sectional community-based survey was conducted. From six districts, a total of 48 villages were selected by a multistage cluster random sampling technique. A total of 3900 people who were selected randomly from 1200 households were assessed for signs of trachoma. Ophthalmic nurses used a simplified clinical grading system to assess stages of trachoma while environmentalists assessed risk factors for trachoma. RESULTS: Of the 3900 people examined, 13% had trachomatous follicles (TF), 27% intense trachomatous inflammation (TI), 17.7% trachomatous scarring (TS), 3.4% trachomatous trichiasis (TT) and 0.3% had corneal opacity (CO). The presence of a kitchen with chimney had a protective effect on TS (Adjusted Odds Ratio [AOR] = 0.82; 95% Confidence Interval [CI]: 0.65-0.96) and TT (AOR = 0.80; 95% CI: 0.53; 0.97). Active trachoma was more prevalent among children (AOR = 0.97; 95% CI: 0.96-0.97), illiterates (AOR = 1.38; 95% CI: 1.13-1.69) and those who infrequently wash their face (AOR = 1.35; 95% CI: 1.18-1.54). CONCLUSIONS: Trachoma is hyperendemic in the Tigray region. Mass chemotherapy, the expansion of primary eye care services, and promotion of a regular face washing habit are recommended. We recommend further investigations on the effect of domestic use of biomass energy on trachoma.


Asunto(s)
Vigilancia de la Población , Tracoma/epidemiología , Adolescente , Adulto , Niño , Estudios Transversales , Etiopía/epidemiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Estudios Retrospectivos , Factores de Riesgo , Población Rural
17.
Nature ; 438(7069): 796-9, 2005 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-16319825

RESUMEN

Aerosols in Titan's atmosphere play an important role in determining its thermal structure. They also serve as sinks for organic vapours and can act as condensation nuclei for the formation of clouds, where the condensation efficiency will depend on the chemical composition of the aerosols. So far, however, no direct information has been available on the chemical composition of these particles. Here we report an in situ chemical analysis of Titan's aerosols by pyrolysis at 600 degrees C. Ammonia (NH3) and hydrogen cyanide (HCN) have been identified as the main pyrolysis products. This clearly shows that the aerosol particles include a solid organic refractory core. NH3 and HCN are gaseous chemical fingerprints of the complex organics that constitute this core, and their presence demonstrates that carbon and nitrogen are in the aerosols.


Asunto(s)
Medio Ambiente Extraterrestre/química , Compuestos Orgánicos/análisis , Saturno , Aerosoles/química , Amoníaco/análisis , Atmósfera/química , Carbono/análisis , Cromatografía de Gases y Espectrometría de Masas , Gases/análisis , Gases/química , Calor , Cianuro de Hidrógeno/análisis , Nitrógeno/análisis
18.
Nature ; 438(7069): 779-84, 2005 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-16319830

RESUMEN

Saturn's largest moon, Titan, remains an enigma, explored only by remote sensing from Earth, and by the Voyager and Cassini spacecraft. The most puzzling aspects include the origin of the molecular nitrogen and methane in its atmosphere, and the mechanism(s) by which methane is maintained in the face of rapid destruction by photolysis. The Huygens probe, launched from the Cassini spacecraft, has made the first direct observations of the satellite's surface and lower atmosphere. Here we report direct atmospheric measurements from the Gas Chromatograph Mass Spectrometer (GCMS), including altitude profiles of the constituents, isotopic ratios and trace species (including organic compounds). The primary constituents were confirmed to be nitrogen and methane. Noble gases other than argon were not detected. The argon includes primordial 36Ar, and the radiogenic isotope 40Ar, providing an important constraint on the outgassing history of Titan. Trace organic species, including cyanogen and ethane, were found in surface measurements.


Asunto(s)
Atmósfera/química , Medio Ambiente Extraterrestre/química , Cromatografía de Gases y Espectrometría de Masas/instrumentación , Vuelo Espacial , Argón/análisis , Carbono/análisis , Carbono/química , Isótopos/análisis , Metano/análisis , Metano/química , Nitrógeno/análisis , Nitrógeno/química , Vuelo Espacial/instrumentación
19.
J Chromatogr A ; 982(2): 303-12, 2002 Dec 27.
Artículo en Inglés | MEDLINE | ID: mdl-12489887

RESUMEN

As part of the development of the European Space Agency Rosetta space mission to investigate a cometary nucleus, the selection of columns dedicated to the gas chromatographic subsystem of the Cometary Sampling and Composition (COSAC) experiment was achieved. Once the space probe launched, these columns will be exposed to the harsh environmental constraints of space missions: vibrations, radiation (by photons or energetic particles), space vacuum, and large temperature range. In order to test the resistance of the flight columns and their stationary phases, the columns were exposed to these rough conditions reproduced in the laboratory. The comparison of the analytical performances of the columns, evaluated prior and after the environmental tests, demonstrated that all the columns withstand space constraints, and that their analytical properties were preserved. Therefore, all the selected capillary columns, even having porous layer or chiral stationary phases, were qualified for space exploration.


Asunto(s)
Cromatografía de Gases/instrumentación , Meteoroides , Vuelo Espacial
20.
Adv Space Res ; 27(2): 195-9, 2001.
Artículo en Inglés | MEDLINE | ID: mdl-11605632

RESUMEN

If there is, or ever was, life in our solar system beyond the Earth, Mars is the most likely place to search for. Future space missions will have then to take into account the detection of prebiotic molecules or molecules of biological significance such as amino acids. Techniques of analysis used for returned samples have to be very sensitive and avoid any chemical or biological contamination whereas in situ techniques have to be automated, fast and low energy consuming. Several possible methods could be used for in situ amino acid analyses on Mars, but gas chromatography would likely be the most suitable. Returned samples could be analyzed by any method in routine laboratory use such as gas chromatography, already successfully performed for analyses of organic matter including amino acids from martian meteorites. The derivatization step, which volatilizes amino acids to perform both in situ and laboratory analysis by gas chromatography, is discussed here.


Asunto(s)
Aminoácidos/análisis , Exobiología/instrumentación , Marte , Cromatografía de Gases , Medio Ambiente Extraterrestre , Suelo/análisis , Vuelo Espacial/instrumentación
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