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1.
Bull Environ Contam Toxicol ; 96(4): 443-8, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26886426

RESUMO

Soil and plant samples were collected from sewage and tubewell irrigated sites from three industrially different cities of Punjab (India) viz. Ludhiana, Jalandhar and Malerkotla. The extent of lead (Pb) pollution was assessed with respect to background concentration of tubewell irrigation. In sewage irrigated surface soil layer (0-15 cm), the extent of Pb accumulation was 4.61, 4.20 and 2.26 times higher than those receiving tubewell irrigation sites in Ludhiana, Jalandhar and Malerkotla, respectively. Multiple regression analysis showed that soil pH, organic carbon, calcium carbonate and clay were significant soil parameters explaining the variation in available soil Pb. The mean Pb content in plants receiving sewage irrigation was 4.56, 5.48 and 2.72 times higher than tubewell irrigation in Ludhiana, Jalandhar and Malerkotla, respectively. The content of Pb in plants receiving sewage irrigation revealed that, assuming a weekly consumption of 500-1000 g of vegetables grown on sewage irrigated soils by an adult of 70 kg body weight, the Pb intake may far exceed the World Health Organization proposed tolerable weekly intake of Pb.


Assuntos
Irrigação Agrícola/métodos , Monitoramento Ambiental/métodos , Chumbo/análise , Esgotos/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Cidades , Índia , Solo/química , Verduras/química , Verduras/crescimento & desenvolvimento , Água/análise
2.
Infect Control Hosp Epidemiol ; 36(2): 160-8, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25632998

RESUMO

OBJECTIVES: No previous studies of methicillin-resistant Staphylococcus aureus (MRSA) epidemiology in adult intensive care units (ICUs) have assessed the utility of rapid, highly discriminatory strain typing in the investigation of transmission events. DESIGN: Observational. SETTING: A 22-bed medical-surgical adult ICU. Patients Those admissions MRSA-positive on initial screening and all admissions <48 hours in duration were excluded, leaving a cohort of 653 patients (median age, 61 years; APACHE-II, 19). METHODS: We conducted this study of MRSA transmission over 1 year (August 1, 2011 to July 31, 2012) using a multiplex PCR-based reverse line blot (mPCR/RLB) assay to genotype isolates from surveillance swabs obtained at admission and twice weekly during ICU stays. MRSA prevalence and incidence rates were calculated and transmission events were identified using strain matching. Colonization pressure was calculated daily by summation of all MRSA cases. RESULTS: Of 1,030 admissions to ICU during the study period, 349 patients were excluded. MRSA acquisition occurred during 31 of 681 (4.6%) remaining admissions; 19 of 31(61%) acquisitions were genotype-confirmed, including 7 (37%) due to the most commonly transmitted strain. Moving averages of MRSA patient numbers on the days prior to a documented event were used in a Poisson regression model. A significant association was found between transmission and colonization pressure when the average absolute colonization pressure on the previous day was ≥3 (χ2=7.41, P=0.01). CONCLUSIONS: mPCR/RLB characterizes MRSA isolates within a clinically useful time frame for identification of single-source clusters within the ICU. High MRSA colonization pressure (≥3 MRSA-positive patients) on a given day is associated with an increased likelihood of a transmission event.


Assuntos
Infecção Hospitalar/epidemiologia , Técnicas de Genotipagem , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/transmissão , Infecção Hospitalar/microbiologia , Humanos , Incidência , Unidades de Terapia Intensiva , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase Multiplex , Prevalência , Infecções Estafilocócicas/microbiologia , Centros de Atenção Terciária
3.
Anaesth Intensive Care ; 41(5): 623-30, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23977914

RESUMO

Cricothyroidotomy is infrequently performed in the intensive care unit but may be a lifesaving procedure. The aim of this study was to determine the number of attempts required by trainees to gain adequate skills for a successful cricothyroidotomy (defined as lung inflation <60 seconds). The effect of training on time to completion of cricothyroidotomy was also studied. After viewing a demonstration video on the procedure, each participant attempted cricothyroidotomy five times consecutively on a manikin with a pre-assembled Melker cricothyroidotomy kit. Time from 'skin' palpation to 'lung' inflation was recorded for 30 participants. Time to completion of cricothyroidotomy decreased over consecutive attempts within each participant (F4df=39.6; P <0.001) and between participant variability in times recorded at each attempt also decreased (P=0.04). Overall improvement in time to completion was seen even between the fourth and fifth attempts (mean difference -6.3 seconds; P <0.001). All participants were successful by the fifth attempt, by which stage all but two had been successful on two consecutive attempts. Age, years of postgraduate practice and level of seniority appeared to be associated with earlier success. Consecutive attempts on a manikin led to an improvement in the time to completion of cricothyroidotomy and rate of a successful outcome (<60 seconds). We recommend that clinicians undergo at least five training attempts on a manikin to gain proficiency in cricothyroidotomy.


Assuntos
Manuseio das Vias Aéreas , Cartilagem Cricoide/cirurgia , Tireoidectomia/educação , Adulto , Emergências , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fatores de Tempo
4.
Anaesth Intensive Care ; 37(6): 961-7, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20014603

RESUMO

We compared three different cricothyroidotomy techniques on a cadaveric porcine airway model to determine the most rapid, successful and safe method in emergency situations. In this observational comparative bench-test, surgical or scalpel cricothyroidotomy (ST), Cook Melker Cricothyrotomy Kit (CM) and Portex Cricothyroidotomy Kit (PCK) were evaluated. After a familiarisation program, four operators performed five procedures using each of the techniques. A dissected pig airway was housed in an airway training manikin. Time to successful completion of the procedure, complications and anatomical variations in the pig larynx were recorded. A patent airway was established in 20 of 20 (100%) attempts with CM technique, 11 of 20 (55%) with ST and six of 20 (30%) with PCK technique. The CM technique was associated with a higher success rate (P <0.001). There was no significant difference (P=0.4) in the median time (interquartile range) taken to achieve a patent airway; CM 50 seconds (40 to 57), ST 47 seconds (41 to 55) and PCK 63 seconds (41 to 150). There was a higher rate of posterior tracheal wall injury with the PCK technique (n=11) and ST technique (n=5). No complications were observed with CM technique. There were no significant anatomical variations in the pig larynxes. We conclude that the CM technique is safe, rapid and has a significantly higher success rate in achieving an artificial airway in this airway model. Overall, all the participants in our study preferred to use this kit in an emergency situation.


Assuntos
Cartilagem Cricoide/cirurgia , Tratamento de Emergência/métodos , Animais , Tratamento de Emergência/efeitos adversos , Tratamento de Emergência/instrumentação , Desenho de Equipamento , Manequins , Modelos Animais , Complicações Pós-Operatórias/etiologia , Suínos , Fatores de Tempo
5.
Postgrad Med J ; 85(1002): 219-22, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19417173

RESUMO

Some patients with type 2 diabetes mellitus (T2DM) are profoundly insulin resistant and require large insulin doses to achieve optimal glycaemic control. However, large volumes of subcutaneous conventional U-100 insulin can cause discomfort at the injection site, resulting in poor concordance with insulin therapy. One therapeutic option is the use of U-500 insulin, thus reducing the insulin volume by 80%. This review will address the practical issues associated with the use of U-500, clinical efficacy and safety aspects of this concentrated insulin, which has an important role in a subgroup of patients with T2DM.


Assuntos
Diabetes Mellitus Tipo 2/tratamento farmacológico , Hipoglicemiantes/administração & dosagem , Resistência à Insulina/fisiologia , Insulina/administração & dosagem , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/economia , Custos de Medicamentos , Humanos , Hipoglicemiantes/efeitos adversos , Hipoglicemiantes/economia , Insulina/efeitos adversos , Insulina/economia , Obesidade/complicações , Satisfação do Paciente , Resultado do Tratamento , Aumento de Peso
6.
Environ Monit Assess ; 154(1-4): 53-64, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18612834

RESUMO

The disposal of industrial and sewage water is a problem of increasing importance throughout the world. In India, and most of the developing countries untreated sewage and industrial wastes are discharged on land or into the running water streams which is used for irrigating crops. These wastes often contain high amount of trace elements which may accumulate in soils in excessive quantities on long term use and enter the food chain through absorption by the plants. Among the trace metals, Cd has received the greater attention because of its easy absorption and accumulation in plants and animals to levels toxic for their health. The objective of this study conducted in three industrially different cities viz., Ludhiana, Jalandhar and Malerkotla was to monitor the extent of Cd accumulation in soils and plants receiving untreated sewage water. Plant and soil samples were collected from sewage and tubewell irrigated areas. Soil samples were analysed for texture, pH, EC, organic carbon (OC), CaCO(3), bioavailable DTPA-Cd and plant samples were analysed for total Cd. In sewage irrigated soils, the mean values of pH were lower but organic carbon and electrical conductivity were generally higher both in surface and sub-surface layers of all the three cities as compared to tubewell irrigated soils. The mean DTPA- extractable Cd in sewage irrigated soil was 6.3- and 4.36-fold in Ludhiana, 3.38- and 1.71-fold in Jalandhar and 3.35- and 6.67-fold in Malerkotla in 0-15 and 15-30 cm soil depth, respectively, compared with the values in tubewell irrigated soils. The accumulation of DTPA-Cd in sewage irrigated soils was restricted to 30 cm depth after which the values were generally close to values in tubewell irrigated soils. Soil pH, OC, CaCO(3), clay and silt collectively accounted for 37.1%, 65.1% and 53.9% DTPA-extractable bioavailable Cd in soils of Ludhiana, Jalandhar and Malerkotla, respectively. Lower R(2) values in Ludhiana suggest that factors other than the ones mentioned may be affecting Cd availability. At all sites plants receiving sewage irrigation had elevated levels of Cd as compared to the plants receiving tubewell irrigation. The mean Cd content of sewage irrigated plants irrespective of the city was 5.96 microg g(-1) dry matter as compared to 0.98 microg g(-1) dry matter in tubewell irrigated plants. The results suggest that the intake of Cd obtained from consumption of crops grown on sewage irrigated soils would be much higher than the tolerable limits set by WHO and may, therefore, prove potentially toxic leading to various health ailments to humans and animals.


Assuntos
Cádmio/análise , Plantas/metabolismo , Esgotos/análise , Poluentes do Solo/análise , Poluentes Químicos da Água/análise , Cádmio/metabolismo , Cidades , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Índia , Solo/análise
7.
Anaesth Intensive Care ; 35(5): 707-13, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17933156

RESUMO

Atrial fibrillation is a common arrhythmia in an intensive care unit. We performed a prospective observational study over a period of three months, to study the incidence, risk factors and outcome of patients who develop atrial fibrillation in a multidisciplinary intensive care unit. All patients above the age of 50 years were eligible. Exclusion criteria were: cardiac or oesophageal surgery during current hospitalisation, atrial fibrillation at admission, implanted pacemaker and expected intensive care unit stay of less than 24 hours. Sixty-one patients were included in the study. Eighteen patients (29.5%, confidence interval 18-40) developed atrial fibrillation. Incidence of atrial fibrillation was 4.02 episodes per 100 patient days. Patients who developed atrial fibrillation had higher age (71.3 years vs. 63.2 years, P=0.001), severity of illness (APACHE II 25.4 vs. 20.0, P=0.005) and sepsis at admission (9/18 vs. 9/43, P=0.01). They also had higher in-hospital mortality (Risk ratio 2.7, 95% confidence interval 1.3-5.4). Standardised mortality ratio was higher in patients who developed atrial fibrillation (1.08 vs. 0.63). Patients who developed atrial fibrillation required a longer period of mechanical ventilation and inotropic support. Multivariate logistic regression analysis showed age >75 years, APACHE II score >20 and sepsis at admission were independent predictors for development of atrial fibrillation in critically ill patients. Although atrial fibrillation by itself is unlikely to be the cause of higher mortality, it is likely to be a marker for increased mortality and resource utilisation in the intensive care unit.


Assuntos
Fibrilação Atrial/epidemiologia , Idoso , Fibrilação Atrial/mortalidade , Austrália/epidemiologia , Gasometria , Métodos Epidemiológicos , Feminino , Humanos , Unidades de Terapia Intensiva , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica , Resultado do Tratamento
8.
J Assoc Physicians India ; 53: 853-6, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16459527

RESUMO

AIM: Suicidal hanging is an uncommon medical emergency with significant neurological morbidity. The aim of the study was to identify factors that have a bearing on the final outcome. MATERIALS AND METHODS: Retrospective analysis of 37 consecutive cases of suicidal hanging admitted to our ICU from July 1996 - December 2002 was performed. Outcome at discharge was defined as good (complete neurological recovery) or poor (death or incomplete neurological recovery). Three clinical variables (at presentation) namely Glasgow Coma Scale (GCS) at presentation, time lapse (in hours) from the incident to arrival at our hospital and the presence of Hypotension (defined as a systolic blood pressure < or = 90 mm Hg) at admission were recorded and tested individually for an association with the outcome. Statistical analysis was done using the Odds ratio (OR +/- 95% Confidence Intervals) and Chi-square test of significance for categorical data. RESULTS: Patients with suicidal hanging constituted < 1% of ICU admissions (mean age 27 years). 34/37 survived giving a survival rate of 92%. Of those who survived, 31 patients (91%) had complete neurological recovery at the time of discharge from hospital. Among those who presented <4 hours of the incident (25 patients), 2 had an adverse outcome as compared to 4/10 patients who presented 4 hours or more after the incident (OR 7.6,95% CI 1.12-52.3). A low GCS (GCS <7) at presentation was also statistically associated with a poor outcome (OR 10.4, 95% CI 1.08-102.1). Hypotension was present in approximately 33% of patients (12/37) at presentation. Of these 12 patients, 3 had an adverse outcome as opposed to 3 patients among the remaining 25 (OR 1.6, 95% CI 0.41 - 14.47, NS). CONCLUSIONS: Suicidal hanging is an unusual medical emergency that is common among young individuals in developing countries. Our study indicates that a delayed presentation to a medical facility and a low GCS at presentation predict a poor outcome.


Assuntos
Lesões do Pescoço/patologia , Suicídio/estatística & dados numéricos , Adulto , Feminino , Escala de Coma de Glasgow , Humanos , Hipotensão/epidemiologia , Índia/epidemiologia , Masculino , Recuperação de Função Fisiológica , Estudos Retrospectivos , Fatores de Tempo
9.
J Assoc Physicians India ; 51: 816-7, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-14651148

RESUMO

Hepatotoxicity following acute poisoning with rodenticides has been infrequently reported in literature. To emphasize the fact that this form of clinical presentation is not unusual we are reporting two cases of rodenticide poisoning masquerading as severe hepatic dysfunction.


Assuntos
Doença Hepática Induzida por Substâncias e Drogas/etiologia , Falência Hepática/induzido quimicamente , Rodenticidas/intoxicação , Adulto , Doença Hepática Induzida por Substâncias e Drogas/diagnóstico , Evolução Fatal , Feminino , Humanos , Fígado/patologia , Falência Hepática/diagnóstico , Intoxicação/diagnóstico
10.
Crit Care Med ; 26(8): 1361-7, 1998 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9710095

RESUMO

OBJECTIVES: To determine the cardiorespiratory effects of manual expiratory rib cage compression in mechanically ventilated patients recovering from acute severe asthma; and to extrapolate these findings to emergency asthma management where ventilation cannot be achieved by positive-pressure ventilation. DESIGN: A prospective, clinical study. SETTING: Intensive care unit. PATIENTS: Four intubated, mechanically ventilated (volume-controlled), adult patients recovering from acute severe asthma. INTERVENTIONS: Patients were studied before, during, and after a 2- to 3-min period of manual compressions applied bilaterally over the lower rib cage (ribs 8 to 10) during consecutive tidal expirations. MEASUREMENTS AND MAIN RESULTS: Air flow (pneumotachograph), airway pressure, radial or brachial arterial pressure, and the hand pressure applied to the patient's rib cage were monitored and recorded on magnetic tape. Playback of the recorded data enabled measurement of changes in lung volume (air flow integration). Changes during rib cage compression consisted chiefly of small decreases in lung volume and peak inspiratory airway pressure that were only observed in the least obstructed patient and were fully reversed after the cessation of compressions. Air flow-time and air flow-volume plots demonstrated expiratory air flow limitation during essentially the entire tidal expiration in each patient, except the least obstructed patient. CONCLUSION: The results suggest that manual compression of the rib cage during consecutive tidal expirations would be ineffective in reducing pulmonary hyperinflation during the emergency management of asthma when air flow obstruction is so severe that ventilation cannot be achieved by positive-pressure ventilation.


Assuntos
Asma/fisiopatologia , Asma/terapia , Reanimação Cardiopulmonar/métodos , Pulmão/fisiopatologia , Respiração com Pressão Positiva/métodos , Mecânica Respiratória , Doença Aguda , Adulto , Feminino , Seguimentos , Humanos , Masculino , Estudos Prospectivos , Costelas , Volume de Ventilação Pulmonar/fisiologia
11.
Indian J Pathol Microbiol ; 40(4): 521-5, 1997 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-9444865

RESUMO

ESR (Westergen) correlated significantly with the iron status (as measured by Hb concentration, haematocrit, red cell count, MCH, P/H ratio, serum iron, TIBC and percent saturation of transferrin) in a group of pregnant women (PW) at term. Serum ferritin correlated negatively with the ESR but the correlation was not statistically significant. Serum ferritin levels of < 50 micrograms/L were present in 9 (34.6%) PW with ESR > or = 50 mm 1st hour and 5 (19.2%) PW with ESR < 50 mm 1st hour. The mean ESR in PW was 55.7 (+/- 22.9) and was > or = 50 mm 1st hour in 50% and < 75 mm 1st hour in 82.7%. The difference in the mean ESR in anaemic and nonanaemic PW was highly significant (p < 0.001), 87.5% anaemic PW with serum ferritin > 50 micrograms/L had ESR > or = 50 mm 1st hour, suggesting the possible effect of chronic infection in raising ferritin levels in these PW.


Assuntos
Sedimentação Sanguínea , Hemoglobinas/análise , Ferro/sangue , Gravidez/sangue , Contagem de Eritrócitos , Feminino , Ferritinas/sangue , Hematócrito , Humanos
13.
J Assoc Physicians India ; 41(2): 84-7, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-8335614

RESUMO

Cardiovascular risk factors in NIDDM were studied by comparing 175 subjects with coronary heart disease (CHD) to 173 subjects without CHD; both groups were matched with regard to male to female ratio, age at diagnosis of diabetes and body mass index. The risk factors included were hypertension, poor metabolic control, smoking and lipid abnormalities. Since the mean known duration of diabetes in subjects with CHD was longer compared to those without CHD (12.93 +/- 7.23 and 6.25 +/- 5.66) and sub sample of subjects from both groups with duration of diabetes with 15 years or less were also analysed for comparison. Even after adjustment of duration the clustering of vascular complication in the subjects with CHD was striking. Presence of low HDL cholesterol was significant in both men and women diabetics with CHD (p < 0.01); while hypertension and poor metabolic control showed a strong positive correlation to CHD in women (p < 0.01 & p < 0.05). Multiple logistic analysis carried out separately in men and women showed that both low HDL cholesterol and elevated serum triglycerides showed strong association to CHD in both sexes; while in women in addition hypertension and insulin therapy also had a positive correlation to CHD (p < 0.01). Furthermore the influence of known duration of diabetes was not observed to be a significant contributor to the cardiovascular risk factors, since the above mentioned risk factors remained statistically significant in the subsample of patients with duration of diabetes less than 15 years.


Assuntos
Doença das Coronárias/epidemiologia , Diabetes Mellitus Tipo 2/epidemiologia , Glicemia/metabolismo , HDL-Colesterol/sangue , Doença das Coronárias/complicações , Diabetes Mellitus Tipo 2/complicações , Angiopatias Diabéticas/epidemiologia , Feminino , Humanos , Hipertensão/epidemiologia , Masculino , Pessoa de Meia-Idade , Análise de Regressão , Fatores de Risco , Fumar/epidemiologia , Fatores de Tempo , Triglicerídeos/sangue
14.
J Intern Med ; 233(1): 81-3, 1993 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-8429293

RESUMO

A case of a 17-year-old Indian male with disseminated tuberculosis is reported. While on chemotherapy, he was detected to have splenic abscesses. The patient remained unresponsive to antituberculous drugs until a splenectomy was performed.


Assuntos
Abscesso/cirurgia , Antituberculosos/uso terapêutico , Esplenectomia , Tuberculose Esplênica/cirurgia , Tuberculose/tratamento farmacológico , Tuberculose/cirurgia , Abscesso/microbiologia , Adolescente , Quimioterapia Combinada , Humanos , Masculino
15.
Indian J Chest Dis Allied Sci ; 34(4): 197-204, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1302753

RESUMO

Patients with obstructive airways disease (asthma and chronic obstructive airways disease) with an acute exacerbation of symptoms were studied. Those requiring hospitalization were chosen to study the pattern of respiratory pathogens isolated on a supervised sputum culture. Certain variables were studied in a case control design to determine an association with culture positivity.


Assuntos
Asma/microbiologia , Infecções Bacterianas/epidemiologia , Espasmo Brônquico/microbiologia , Pneumopatias Obstrutivas/microbiologia , Infecções Respiratórias/epidemiologia , Escarro/microbiologia , Doença Aguda , Adulto , Infecções Bacterianas/diagnóstico , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Infecções Respiratórias/diagnóstico
16.
J Assoc Physicians India ; 40(6): 373-6, 1992 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-1452560

RESUMO

The effect of betamethasone on the outcome in moderate to severe tetanus was studied in a randomised, double blind, placebo controlled study in 22 patients. The mortality rate was reduced by 36.1% with the addition of corticosteroids to the regime of treatment. Betamethasone did not alter the duration of intensive care in those requiring it, but reduced the need for tracheostomy and ventilation. The mean daily dose of diazepam required was not significantly different between the two groups and there was no increase in the incidence of infections in the betamethasone group.


Assuntos
Betametasona/administração & dosagem , Países em Desenvolvimento , Tétano/tratamento farmacológico , Adulto , Método Duplo-Cego , Feminino , Humanos , Índia , Infusões Intravenosas , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Taxa de Sobrevida , Tétano/mortalidade
18.
Appl Opt ; 17(14): 2176-80, 1978 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-20203752

RESUMO

We have investigated the dependence of two-point resolution by an aberration-free Gaussian aperture on the real part of the complex degree of coherence. The Sparrow and the modified Rayleigh criteria have been used for the partially coherent optical systems, and a comparison between them has been made. To reveal important information concerning the characteristics of the image, the irradiance distribution from two mutually partially coherent point sources has also been computed.

20.
Appl Opt ; 16(9): 2460-3, 1977 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-20168951

RESUMO

This paper presents a theoretical study of the effects of partial coherence (via the effect of condenser aperture) on the resolution of two pinholes by a semitransparent and pi-phase annular aperture microscope. The illumination used is nonuniform and nonsymmetric. The response of the resolution has been studied in three discrete planes of illumination. It has been seen that by making the central region of the pi-phase annular aperture completely transparent, best resolution is obtained in the plane of illumination ø = pi/2. The oscillatory behavior of the limiting resolution has also been displayed graphically.

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