RESUMO
We present a method for using liquid-crystal variable retarders (LCVR's) with continually varying voltage to measure the Stokes vector of a light beam. The LCVR's are usually employed with fixed retardance values due to the nonlinear voltage-retardance behavior that they show. The nonlinear voltage-retardance relationship is first measured and then a linear fit of the known retardance terms to the detected signal is performed. We use known waveplates (half-wave and quarter-wave) as devices to provide controlled polarization states to the Stokes polarimeter and we use the measured Stokes parameters as functions of the orientation of the axes of the waveplates as an indication of the quality of the polarimeter. Results are compared to a Fourier analysis method that does not take into account the nonlinear voltage-retardance relationship and also to a Fourier analysis method that uses experimental voltage values to give a linear retardance function with time. Also, we present results of simulations for comparison.
RESUMO
Since 1994, when the NIST/NOAA Quality Assurance Program in Chemical Measurements was discussed in Queretaro, CENAM, the National Measurement Institute (NMI) of Mexico, has become involved in the development of reference materials. In the field of biological and environmental reference materials, in particular, the NORAMET collaboration program with NIST and NRC, and the North-American Environmental Cooperation signed among three free-trade treaty organizations, have greatly helped the development of the materials metrology program in the newly established CENAM. This paper describes some particularly significant efforts of CENAM in the development of biological and environmental reference materials, on the basis of inter-comparison studies organized with local and governmental environmental agencies of Mexico. In the field of water pollution CENAM has developed a practical proficiency testing (PT) scheme for field laboratories, as a part of registration by local government in the metropolitan area, according to the Mexican Ecological Regulation. The results from these eight PTs in the last 5 years have demonstrated that this scheme has helped ensure the reliability of analytical capability of more than 50 field laboratories in three states, Mexico, D.F., and the States of Mexico and Queretaro. Similar experience has been obtained for more than 70 service units of stack emission measurements in the three states in 1998 and 1999, as a result of the design of a PT scheme for reference gas mixtures. This PT scheme has been accomplished successfully by 30 analytical laboratories who provide monitoring services and perform research on toxic substances (Hg, methylmercury, PCB, etc.) in Mexico. To support these activities, reference samples have been produced through the NIST SRMs, and efforts have been made to increase CENAM's capability in the preparation of primary reference materials in spectrometric solutions and gas mixtures. Collaboration among NMIs has also successfully overcome the inability of CENAM to prepare biological tissue for mercury assessment and marine sediments for analysis of trace metals. The importance of international collaboration is stressed not only in the NORAMET region but also in the SIM, to provide help for each other and achieve mutual recognition among member countries of the region.
Assuntos
Monitoramento Ambiental/normas , Padrões de Referência , Técnicas de Química Analítica/métodos , Técnicas de Química Analítica/normas , Monitoramento Ambiental/métodos , Poluentes Ambientais/análise , Poluentes Ambientais/normas , Cooperação Internacional , MéxicoRESUMO
INTRODUCTION: An essential step, prior to the introduction into paediatric practice of visual evoked potentials (VEP) caused by stimulation with light emitting diodes (LED) is their description at different stages of maturity of the nervous system. PATIENTS AND METHODS: We obtained VEP to LED in a group of 60 children aged between 1 and 5 years, who were functionally healthy and equally distributed with regard to age and sex. In each case we recorded the responses to monocular stimulation (right and left), binocular stimulation and without stimulation (replicas of each condition). The recordings were made under sedation with secobarbital at a dose of 3 mg/kg body weight. RESULTS: Our results showed a significant reduction in the latency of all components (except P3) and the amplitude of N1 and P1, as a function of the age of the child. The response to LED is reproducible (especially intra individual) with up to three types of morphology observed. Sedation did not affect detection of the response. The only significant effect was a reduction in the amplitude of P1. CONCLUSIONS: We confirmed the changes due to maturity, reflected in a significant reduction of the latency of most components with increasing age. By between 4 and 6 years old the figures obtained were similar to those in adults. The results obtained give us the opportunity chance of publishing this standard data so that better use and interpretation of VEP to LED at an early age may be possible.
Assuntos
Potenciais Evocados Visuais/fisiologia , Testes Neuropsicológicos/normas , Sistema Nervoso Central/crescimento & desenvolvimento , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Estimulação Luminosa , Tempo de ReaçãoRESUMO
We presented two cases of falsely elevated CK-MB due to the presence of a type 2 macro CK, showed by isoenzymes electrophoresis. The association of this CK-MB falsely elevated with some digestive diseases are frequent. Quantification of CK isoenzymes by electrophoresis could be indicated in those cases in which the clinical course or ECG changes do not correlate with the CK-MB values.
Assuntos
Colecistite/sangue , Creatina Quinase/sangue , Idoso , Reações Falso-Positivas , Feminino , Humanos , Isoenzimas , MasculinoRESUMO
Due to persistence of poliomyelitis cases in the Pacific Coast of Mexico and particularly in the state of Sinaloa, a house to house vaccination strategy named "Sinaloa Operation" was carried out in 100% of the territory of this state. Sinaloa was divided in small geographical and statistical unit area (AGEB). Simultaneously, teams of nurse carried out a population census of children under five years old and pregnant women. Nurses vaccinated the children with Sabin trivalent vaccine in undiscriminating form. These activities were made in three phases. In the last phase (February 1991) 301, 441 Sabin vaccine doses were administered. This figure represents an extension of the vaccination coverage to the children of the seasonal migrant workers from other parts of the country. As a result of this programme. Sinaloa has not had any other polio case since two years ago.
Assuntos
Poliomielite/prevenção & controle , Vacina Antipólio de Vírus Inativado/administração & dosagem , Vacinação/métodos , Pré-Escolar , Humanos , Lactente , México , Avaliação de Programas e Projetos de Saúde , População Rural , População UrbanaRESUMO
In our IVF & related techniques program, clomiphene 50 mg was used from days 2 to 6 of the cycle in 20 patients and 20 cycles. (17 IVF patients and 3 GIFT patients) menotropins were also used in 2 different schemes: a) 2 ampules in alternated days (12 cases) and b) one ampule daily (8 cases). The patients with the daily scheme required lesser total dose of menotropins and developed higher estradiol levels, although this had none statistic significance, and they also developed a greater number of follicles. There were 16 laparoscopies for ovum capture and 53 oocytes were retrieved (30.2% mature) 10 oocytes were from the GIFT patients. 16 oocytes were fertilized and 8 cleaved. There was only one pregnancy from and IVF patient with the alternated scheme that ended with a first trimester abortion.
Assuntos
Clomifeno/administração & dosagem , Menotropinas/administração & dosagem , Indução da Ovulação/métodos , Adulto , Estradiol/sangue , Feminino , Fertilização in vitro , Transferência Intrafalopiana de Gameta , Humanos , Oócitos/crescimento & desenvolvimento , Folículo Ovariano/fisiologia , Zigoto/crescimento & desenvolvimentoRESUMO
Se implantaron 12 catéteres en 10 pacientes con sindrome dolorosa por cáncer y en 1 con neuropatia periférica y se administraron solamente opioides extradurales en la mayoria de los casos. La duración del tratamiento varió de 1 a 180 días, y 2 pacientes permanecieron con su catéter funcionando más de 100 días. Sólo un catéter se reimplantó y 3 fueron retirados. Como complicación se observó la formación de 2 fístulas epidural-piel y un absceso a nivel de la salida del catéter de la piel. No se presentó infección extradural. Concluímos que la implantación de catéteres epidurales con la técnica de Grunwald es segura y simples de realizar
Assuntos
Pessoa de Meia-Idade , Humanos , Masculino , Feminino , Analgesia EpiduralRESUMO
Los autores reportamos la extraccion completa de un teratoma benigno intracraneal neonatal intraventricular. La revision de cirugias previas en grupos neonatales, demostro que la cirugia electiva es la excision completa del tumor, aunque no ha sido reportada sobrevida y desarrollo neurologico normal. La patologia y pronostico de esta rara neoplasia son discutidos; la dificultad para predecir el curso benigno o maligno justifica extrema precaucion en la vigilancia del paciente y los reportes dados a la familia sobre su evolucion y futuro. La reintervencion del paciente esta indicada en tumores benignos recurrentes; en los tumores malignos talvez respondan a la terapia combinada de irradiacion y quimioterapia
Assuntos
Humanos , Feminino , Masculino , Cerebelo/patologia , Teratoma , Colômbia , Teratoma/complicações , Teratoma/diagnóstico , Teratoma/epidemiologia , Teratoma/patologia , Teratoma/cirurgiaAssuntos
Dieta , Hormônios/análise , Adolescente , Adulto , Neoplasias da Mama/epidemiologia , Chile , Comparação Transcultural , Estrogênios/análise , Feminino , Humanos , Japão , Menstruação , Papua Nova Guiné , Prolactina/análise , Risco , Estados UnidosRESUMO
Eight patients with typical Prinzmetal's angina and angiography proven coronary artery spasm are reviewed. In all cases the angina pain appeared at rest and was accompanied by a simultaneous ST-segment elevation. The coronary angiography results varied from severe multivessel disease (3 cases) to single vessel disease (3 cases), and normal coronary arteries (2 cases). In all patients a coronary spasm was documented, in five cases induced by ergonovine and in three spontaneously; in all patients but in one, the localization of the spasm was concordant with the ST-segment elevation localization. One case with a severe proximal left anterior descending stenosis was grafted; however the pain was not relieved despite treatment with large amounts of propranolol. This patient died after an episode of severe chest pain. Treatment with nifedipine was given to six patients, with excellent results in four cases, and regular response in two. The main physiopathologic diagnostic and therapeutic aspects of the variant angina syndrome are reviewed.
Assuntos
Angina Pectoris Variante/diagnóstico , Vasoespasmo Coronário/diagnóstico , Idoso , Angina Pectoris Variante/complicações , Angina Pectoris Variante/tratamento farmacológico , Vasoespasmo Coronário/tratamento farmacológico , Vasoespasmo Coronário/cirurgia , Eletrocardiografia , Bloqueio Cardíaco/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Nifedipino/uso terapêutico , Propranolol/uso terapêuticoRESUMO
Presentamos 8 pacientes, todos varones y con edades entre 48 y 65 anos, con un sindrome de dolor precordial tipico de angina variante.En todos ellos pudo demostrarse coronariograficamente un espasmo coronario, siendo en tres espontaneo y en cinco provocado mediante metilergonovina intravenosa. En todos los casos, menos uno, la localizacion del espasmo fue concordante con la de la elevacion del espacio ST durante el dolor. En cinco de los pacientes la nifedipina controlo completamente la crisis a largo plazo, y uno de ellos, que no la tomaba, fallecio en el curso de un episodio de angina severa, a pesar de haber sido intervenido previamente de pontaje aorto-coronario a la descendente anterior con exito. En base a estos hallazgos, revisamos los conocimientos actuales sobre la angina variante, especialmente en sus aspectos fisiopatologico, diagnostico y terapeutico