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2.
Int J Tuberc Lung Dis ; 22(11): 1366-1373, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30355418

RESUMO

SETTING: Four ambulatory clinics in Durban, South Africa. OBJECTIVE: To test the relationships of patient characteristics, time to mycobacterial culture positivity, and mortality with urinary lipoarabinomannan (LAM) grade category. DESIGN: Newly diagnosed human immunodeficiency virus (HIV) infected adults were screened for tuberculosis (TB) using sputum culture, tested for urinary LAM, and followed for up to 12 months. We performed multivariable ordinal logistic regression of risk factors for low (1 or 2) or high (3, 4, or 5) LAM grade. We used adjusted Cox regression models to determine the hazard ratios of time to culture positivity and death. RESULTS: Among 683 HIV-infected adults, median CD4 count was 215 cells/mm³ (interquartile range 86-361 cells/mm³), 17% had culture-confirmed TB, and 11% died during follow-up. Smoking, tachycardia (pulse > 100 beats/minute), CD4 count < 100 cells/mm³, and TB culture positivity were each associated with higher LAM grade. In multivariate models, a high urine LAM grade was associated with four-fold increased hazard of culture positivity (P = 0.001) and two-fold increased hazard of mortality (P = 0.02). Among patients treated for TB, these associations were no longer statistically significant. CONCLUSION: In this population, a higher urine LAM grade was associated with shorter time to culture positivity and mortality; however, these associations were not present for those starting anti-tuberculosis treatment.


Assuntos
Infecções por HIV/complicações , Lipopolissacarídeos/urina , Mycobacterium tuberculosis/isolamento & purificação , Tuberculose Pulmonar/diagnóstico , Tuberculose Pulmonar/mortalidade , Adulto , Contagem de Linfócito CD4 , Feminino , Humanos , Modelos Logísticos , Masculino , Análise Multivariada , Pacientes Ambulatoriais , Estudos Prospectivos , Fatores de Risco , Sensibilidade e Especificidade , África do Sul/epidemiologia , Escarro/microbiologia
3.
HIV Med ; 18(7): 513-518, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28070923

RESUMO

OBJECTIVES: Refugees living in Uganda come from HIV-endemic countries, and many remain in refugee settlements for over a decade. Our objective was to evaluate the HIV care cascade in Nakivale Refugee Settlement and to assess correlates of linkage to care. METHODS: We prospectively enrolled individuals accessing clinic-based HIV testing in Nakivale Refugee Settlement from March 2013 to July 2014. Newly HIV-diagnosed clients were followed for 3 months post-diagnosis. Clients underwent a baseline survey. The following outcomes were obtained from HIV clinic registers in Nakivale: clinic attendance ('linkage to HIV care'), CD4 testing, antiretroviral therapy (ART) eligibility, and ART initiation within 90 days of testing. Descriptive data were reported as frequency with 95% confidence interval (CI) or median with interquartile range (IQR). The impact of baseline variables on linkage to care was assessed with logistic regression models. RESULTS: Of 6850 adult clients tested for HIV, 276 (4%; CI: 3-5%) were diagnosed with HIV infection, 148 (54%; CI: 47-60%) of those were linked to HIV care, 54 (20%; CI: 15-25%) had a CD4 test, 22 (8%; CI: 5-12%) were eligible for ART, and 17 (6%; CI: 3-10%) initiated ART. The proportions of refugees and nationals at each step of the cascade were similar. We identified no significant predictors of linkage to care. CONCLUSIONS: Less than a quarter of newly HIV-diagnosed clients completed ART assessment, considerably lower than in other reports from sub-Saharan Africa. Understanding which factors hinder linkage to and engagement in care in the settlement will be important to inform interventions specific for this environment.


Assuntos
Continuidade da Assistência ao Paciente , Infecções por HIV/diagnóstico , Infecções por HIV/tratamento farmacológico , Pesquisa sobre Serviços de Saúde , Refugiados , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Uganda , Adulto Jovem
4.
HIV Med ; 16(10): 640-4, 2015 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25958770

RESUMO

OBJECTIVES: The World Health Organization (WHO) recommends screening HIV-infected people for cryptococcal antigens to identify cryptococcosis, a major cause of AIDS-related deaths. As the burden of cryptococcosis is unknown in South Africa's KwaZulu-Natal province, we assessed the cryptococcal antigenuria prevalence among newly diagnosed HIV-infected adults there. METHODS: We conducted a cross-sectional study of newly diagnosed HIV-infected adults who received voluntary HIV testing in an out-patient clinic. Participants provided a urine specimen in a sterile container, and we performed testing with a WHO-endorsed rapid cryptococcal antigen lateral flow assay (Immy Inc., Norman, OK, USA) per the manufacturer's specifications. We assessed cryptococcal antigenuria prevalence among participants with CD4 counts < 200 cells/µL, and stratified results by CD4 count categories. RESULTS: Among 432 participants, the mean (± standard deviation) age was 36.1 ± 9.9 years and 172 (40%) were female. The overall estimated prevalence of cryptococcal antigenuria was 9.0% [95% confidence interval (CI) 6.5-12.1%]. CD4 counts were available for 319 participants (74%); the median CD4 count was 75 cells/µL [interquartile range (IQR) 34-129 cells/µL]. Participants with a negative cryptococcal antigenuria screening test had a median CD4 count of 79 cells/µL (IQR 36-129 cells/µL), while participants with a positive cryptococcal test had a median CD4 count of 41 cells/µL (IQR 10-112 cells/µL). The estimated prevalence of cryptococcal antigenuria among participants with CD4 counts < 50 cells/µL was 12.5% (95% CI 7.0-20.1%), which was significantly higher than that among participants with CD4 counts of 50-200 cells/µL (4.8%; 95% CI 2.3-8.7%). CONCLUSIONS: Nearly 1 in 10 newly diagnosed HIV-infected adults with CD4 counts < 200 cells/µL in KwaZulu-Natal had evidence of cryptococcal antigenuria. Point-of-care CD4 count testing and cryptococcal antigen screening may rapidly identify cryptococcosis at the time of HIV diagnosis.


Assuntos
Infecções Oportunistas Relacionadas com a AIDS/epidemiologia , Antígenos de Fungos/urina , Criptococose/epidemiologia , Cryptococcus/isolamento & purificação , Infecções por HIV/complicações , Adulto , Antígenos de Fungos/sangue , Contagem de Linfócito CD4 , Estudos Transversais , Criptococose/diagnóstico , Criptococose/urina , Cryptococcus/imunologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prevalência , Fatores de Risco , África do Sul/epidemiologia
5.
HIV Med ; 15(6): 367-72, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24251725

RESUMO

OBJECTIVES: The aim of the study was to assess HIV prevalence, disease stage and linkage to HIV care following diagnosis at a mobile HIV testing unit, compared with results for clinic-based testing, in a Durban township. METHODS: This was a prospective cohort study. We enrolled adults presenting for HIV testing at a community-based mobile testing unit (mobile testers) and at an HIV clinic (clinic testers) serving the same area. Testers diagnosed with HIV infection, regardless of testing site, were offered immediate CD4 testing and instructed to retrieve results at the clinic. We assessed rates of linkage to care, defined as CD4 result retrieval within 90 days of HIV diagnosis and/or completion of antiretroviral therapy (ART) literacy training, for mobile vs. clinic testers. RESULTS: From July to November 2011, 6957 subjects were HIV tested (4703 mobile and 2254 clinic); 55% were female. Mobile testers had a lower HIV prevalence than clinic testers (10% vs. 36%, respectively), were younger (median 23 vs. 27 years, respectively) and were more likely to live >5 km or >30 min from the clinic (64% vs. 40%, respectively; all P < 0.001). Mobile testers were less likely to undergo CD4 testing (33% vs. 83%, respectively) but more likely to have higher CD4 counts [median (interquartile range) 416 (287-587) cells/µL vs. 285 (136-482) cells/µL, respectively] than clinic testers (both P < 0.001). Of those who tested HIV positive, 10% of mobile testers linked to care, vs. 72% of clinic testers (P < 0.001). CONCLUSIONS: Mobile HIV testing reaches people who are younger, who are more geographically remote, and who have earlier disease compared with clinic-based testing. Fewer mobile testers underwent CD4 testing and linked to HIV care. Enhancing linkage efforts may improve the impact of mobile testing for those with early HIV disease.


Assuntos
Serviços de Saúde Comunitária/organização & administração , Continuidade da Assistência ao Paciente/normas , Infecções por HIV , Unidades Móveis de Saúde , Adulto , Antirretrovirais/uso terapêutico , Contagem de Linfócito CD4 , Serviços de Saúde Comunitária/normas , Feminino , Infecções por HIV/diagnóstico , Infecções por HIV/epidemiologia , Infecções por HIV/terapia , Humanos , Masculino , Educação de Pacientes como Assunto , Prevalência , Estudos Prospectivos , África do Sul/epidemiologia , Adulto Jovem
6.
HIV Med ; 12(1): 46-53, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20553336

RESUMO

BACKGROUND: The yield of screening for acute HIV infection among general medical patients in resource-scarce settings remains unclear. Our objective was to evaluate the strategy of using pooled HIV plasma RNA to diagnose acute HIV infection in patients with negative or discordant rapid HIV antibody tests in Durban, South Africa. METHODS: We prospectively enrolled patients with negative or discordant rapid HIV antibody tests from a routine HIV screening programme in an out-patient department in Durban with an HIV prevalence of 48%. Study participants underwent venipuncture for pooled qualitative HIV RNA, and, if this was positive, quantitative RNA, enzyme immunoassay and Western blot (WB). Patients with negative or indeterminate WB and positive quantitative HIV RNA were considered acutely infected. Those with chronic infection (positive RNA and WB) despite negative or discordant rapid HIV tests were considered to have had false negative rapid antibody tests. RESULTS: Nine hundred and ninety-four participants were enrolled with either negative (n=976) or discordant (n=18) rapid test results. Eleven [1.1%; 95% confidence interval (CI) 0.6-2.0%] had acute HIV infection, and an additional 20 (2.0%; 95% CI 1.3-3.1%) had chronic HIV infection (false negative rapid test). CONCLUSIONS: One per cent of out-patients with negative or discordant rapid HIV tests in Durban, South Africa had acute HIV infection readily detectable through pooled serum HIV RNA screening. Pooled RNA testing also identified an additional 2% of patients with chronic HIV infection. HIV RNA screening has the potential to identify both acute and chronic HIV infections that are otherwise missed by standard HIV testing algorithms.


Assuntos
Sorodiagnóstico da AIDS/métodos , Infecções por HIV/epidemiologia , Soroprevalência de HIV , HIV-1/imunologia , Programas de Rastreamento/métodos , RNA Viral/sangue , Doença Aguda , Adulto , Algoritmos , Assistência Ambulatorial , Western Blotting , Doença Crônica , Reações Falso-Negativas , Feminino , Infecções por HIV/sangue , Infecções por HIV/diagnóstico , Humanos , Técnicas Imunoenzimáticas , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Gravidez , Estudos Prospectivos , Kit de Reagentes para Diagnóstico , África do Sul/epidemiologia
7.
HIV Med ; 9(10): 863-7, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18754802

RESUMO

BACKGROUND: Routine HIV testing is increasingly recommended in resource-limited settings. Our objective was to evaluate factors associated with a new diagnosis of HIV infection in a routine HIV testing programme in South Africa. METHODS: We established a routine HIV testing programme in an out-patient department in Durban, South Africa. All registered adults were offered a rapid HIV test; we surveyed a sample of tested patients. RESULTS: During the 12-week study, 1414 adults accepted HIV testing. Of those, 463 (32.7%) were HIV-infected. Seven hundred and twenty (50.9%) were surveyed. Compared with married women, unmarried men were at the highest risk of HIV [odds ratio (OR) 6.84; 95% confidence interval (CI) 3.45-23.55], followed by unmarried women (OR 5.90; 95% CI 3.25-10.70) and married men (OR 4.00; 95% CI 2.04-7.83). Age 30-39 years (compared with >or=50 years; OR 5.10; 95% CI 2.86-9.09), no prior HIV test (OR 1.45; 95% CI 1.07-2.27) and an imperfect HIV knowledge score (OR 2.32; 95% CI 1.24-4.35) were also associated with HIV infection. CONCLUSION: In a routine HIV testing programme in South Africa, rates of previously undiagnosed HIV were highest among men, young and unmarried patients, and those with poorer HIV knowledge. Better interventions are needed to improve HIV knowledge and decrease HIV risk behaviour.


Assuntos
Infecções por HIV/diagnóstico , HIV-1 , Aceitação pelo Paciente de Cuidados de Saúde/estatística & dados numéricos , Adolescente , Adulto , Assistência Ambulatorial , Contagem de Linfócito CD4 , Feminino , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Masculino , Fatores de Risco , África do Sul , Saúde da População Urbana , Adulto Jovem
8.
Opt Lett ; 29(1): 20-2, 2004 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-14719647

RESUMO

An air-core microstructured fiber design that supports a single-polarization, circularly symmetric nondegenerate mode is presented. The fiber design is modeled directly, and the microstructured cladding is analyzed by use of band diagrams to elucidate the mechanism through which polarization nondegeneracy is achieved.

9.
J Law Med ; 9(1): 115-23, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12116660

RESUMO

The abortion law of New Zealand appears to have been interpreted very liberally over recent years by sectors of the medical profession. Indeed the interpretation of the law appears to have been so liberal that it raises questions as to the lawfulness of many of the abortions carried out in New Zealand. The current practice and application of the abortion law is such that it may expose some medical consultants certifying and performing abortions to criminal proceedings and civil claims.


Assuntos
Aborto Criminoso/legislação & jurisprudência , Responsabilidade Legal , Adulto , Direito Penal , Comitês de Ética Clínica/legislação & jurisprudência , Feminino , Humanos , Imperícia/legislação & jurisprudência , Nova Zelândia , Gravidez , Má Conduta Profissional
11.
Opt Express ; 9(7): 319-27, 2001 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-19421303

RESUMO

The first microstructured polymer optical fibre is described. Both experimental and theoretical evidence is presented to establish that the fibre is effectively single moded at optical wavelengths. Polymer-based microstructured optical fibres offer key advantages over both conventional polymer optical fibres and glass microstructured fibres. The low-cost manufacturability and the chemical flexibility of the polymers provide great potential for applications in data communication networks and for the development of a range of new polymer-based fibre-optic components.

12.
Opt Express ; 9(13): 813-20, 2001 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-19424319

RESUMO

Recent developments in polymer microstructured optical fibres allow for the realisation of microstructures in fibres that would be problematic to fabricate using glass-based capillary stacking. We present one class of such structures, where the holes lie on circular rings. A fibre of this type is fabricated and shown to be single moded for relatively long lengths of fibre, whereas shorter lengths are multimoded. An average index model for these fibres is developed. Comparison of its predictions to the calculated properties of the exact structure indicates that the ring structures emulate homogeneous rings of lower refractive index resulting in the ring structured fibres behaving approximately as cylindrically layered fibres.

13.
Australas J Dermatol ; 37(3): 155-6, 1996 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8771873

RESUMO

This report sites two patients with allergic contact dermatitis to topical lignocaine. In separate instances they also developed severe localized reactions following injections of the drug.


Assuntos
Anestésicos Locais/efeitos adversos , Dermatite Alérgica de Contato/etiologia , Lidocaína/efeitos adversos , Administração Cutânea , Anestésicos Locais/administração & dosagem , Toxidermias/etiologia , Feminino , Humanos , Hipersensibilidade Tardia/induzido quimicamente , Injeções Subcutâneas , Lidocaína/administração & dosagem , Pessoa de Meia-Idade
14.
Appl Opt ; 34(31): 7258-62, 1995 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21060593

RESUMO

A field trial of an electrically passive optical-fiber magnetometer incorporated into the transient electromagnetic method of geomagnetic surveying is described. The transducer of the magnetometer consisted of metallic glass wire cocoated with a length of optical fiber. The magnetometer was capable of measuring the decay rate of the surface magnetic field produced by the surveying technique. The sensor's minimum detectable field was 2.5 × 10(-8) G/√Hz at 2 kHz.

15.
Genitourin Med ; 70(5): 317-20, 1994 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8001942

RESUMO

OBJECTIVE: To determine whether the circumcision status of men affected their likelihood of acquiring sexually transmissible diseases (STDs). DESIGN: A cross-sectional study employing an anonymous questionnaire, clinical examination and type specific serology for herpes simplex virus type 2 (HSV-2). SETTING: A public STD clinic in Sydney, Australia. SUBJECTS: 300 consecutive heterosexual male patients. MAIN OUTCOME MEASURES: Associations between circumcision status and past or present diagnoses of STDs including HSV-2 serology and clinical pattern of genital herpes. RESULTS: 185 (62%) of the men were circumcised and they reported similar ages, education levels and lifetime partner numbers as men who were uncircumcised. There were no significant associations between the presence or absence of the male prepuce and the number diagnosed with genital herpes, genital warts and non-gonococcal urethritis. Men who were uncircumcised were no more likely to be seropositive for HSV-2 and reported symptomatic genital herpes outbreaks of the same frequency and severity as men who were circumcised. Gonorrhoea, syphilis and acute hepatitis B were reported too infrequently to reliably exclude any association with circumcision status. Human immunodeficiency virus infection (rare among heterosexual men in the clinic) was an exclusion criterion. CONCLUSIONS: From the findings of this study, circumcision of men has no significant effect on the incidence of common STDs in this developed nation setting. However, these findings may not necessarily extend to other setting where hygiene is poorer and the spectrum of common STDs is different.


Assuntos
Circuncisão Masculina , Herpes Genital/epidemiologia , Adulto , Estudos Transversais , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , New South Wales/epidemiologia , Recidiva , Fatores de Risco
16.
Med J Aust ; 160(11): 697-700, 1994 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-8202004

RESUMO

OBJECTIVE: To identify risk factors, particularly circumcision status, associated with serological evidence of herpes simplex virus type 2 (HSV-2) infection of heterosexual men. DESIGN: A cross-sectional case-control study employing an anonymous delinked interviewer-administered questionnaire, clinical examination, and a type-specific serological test for HSV-2. PARTICIPANTS AND SETTING: Three hundred consecutive heterosexual male patients at a public sexually transmissible diseases (STD) clinic in Sydney, Australia. MAIN OUTCOME MEASURES: Associations between serological evidence of HSV-2 infection and history of genital herpes or contact with genital herpes, history of other common STDs, and demographic and behavioural factors such as age, education level, number of sexual partners and lack of circumcision. RESULTS: One hundred and ninety-four patients (64.7%) had antibodies to HSV-2 but only 24% of these gave a history of genital herpes. A history of genital herpes or sexual contact with genital herpes, reported total lifetime number of sexual partners, failure to complete high school and a history of non-gonococcal urethritis or genital warts were associated with serological evidence of HSV-2 infection at the univariate level. Neither increasing age nor lack of circumcision was associated with HSV-2 infection. Following multivariate analysis only the lifetime number of partners and failure to finish high school were significantly strong predictors of HSV-2 infection. CONCLUSION: This is the highest prevalence of HSV-2 infection ever detected in an Australian population and one of the highest recorded globally. As younger men were as commonly infected as older men, and an earlier (1985) study involving the same clinic yielded a lower prevalence, it appears that a high level of ongoing HSV-2 transmission is occurring among Sydney heterosexuals. Increased awareness of this fact could enhance safer sex campaigns.


Assuntos
Herpes Genital/epidemiologia , Vigilância da População , Infecções Sexualmente Transmissíveis/epidemiologia , Adolescente , Adulto , Fatores Etários , Idoso , Estudos de Casos e Controles , Circuncisão Masculina/estatística & dados numéricos , Comorbidade , Estudos Transversais , Escolaridade , Herpes Genital/sangue , Herpes Genital/prevenção & controle , Herpes Genital/transmissão , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Ambulatório Hospitalar , Prevalência , Fatores de Risco , Parceiros Sexuais , Infecções Sexualmente Transmissíveis/sangue , Infecções Sexualmente Transmissíveis/prevenção & controle , Infecções Sexualmente Transmissíveis/transmissão
17.
Genitourin Med ; 68(3): 159-61, 1992 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-1607190

RESUMO

OBJECTIVE: To determine the incidence of bullous impetigo in a group of homosexual men at high risk of HIV-1 infection. DESIGN: A longitudinal descriptive study (1984-9). SETTING: A private primary care and STD clinic in Sydney, Australia. SUBJECTS: 88 homosexual men documented to seroconvert to HIV-1, and 37 homosexual controls who had practised unprotected anal intercourse with another man known to be HIV-1 positive but who remained HIV-1 negative. MAIN OUTCOME MEASURE: Incidence of bullous impetigo. RESULTS: The crude annual incidence of bullous impetigo was 0.015 in subjects while they remained HIV-1 negative (10 cases) and 0.045 in early HIV-1 positive subjects (2 cases). Overall, 9% of the HIV-1 seroconverters and 9% of the HIV-1 negative controls were documented as suffering bullous impetigo over a mean of 29.2 and 39.3 months, respectively. CONCLUSIONS: Bullous impetigo in an adult could prove to be a clinical indication that a person is either infected with HIV-1 or is in close (possibly sexual) contact with a person with HIV-1 infection. If true, the recognition of bullous impetigo could provide an opportunity for behavioural intervention to limit the spread of HIV-1.


Assuntos
Infecções por HIV/complicações , Homossexualidade , Impetigo/complicações , Austrália , Nádegas , Infecções por HIV/prevenção & controle , Humanos , Impetigo/epidemiologia , Impetigo/patologia , Incidência , Estudos Longitudinais , Masculino , Fatores de Risco , Pele/patologia
19.
Med J Aust ; 153(8): 455-8, 1990 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-2145499

RESUMO

Tea-tree oil (an essential oil of the Australian native tree Melaleuca alternifolia) has long been regarded as a useful topical antiseptic agent in Australia and has been shown to have a variety of antimicrobial activities; however, only anecdotal evidence exists for its efficacy in the treatment of various skin conditions. We have performed a single-blind, randomised clinical trial on 124 patients to evaluate the efficacy and skin tolerance of 5% tea-tree oil gel in the treatment of mild to moderate acne when compared with 5% benzoyl peroxide lotion. The results of this study showed that both 5% tea-tree oil and 5% benzoyl peroxide had a significant effect in ameliorating the patients' acne by reducing the number of inflamed and non-inflamed lesions (open and closed comedones), although the onset of action in the case of tea-tree oil was slower. Encouragingly, fewer side effects were experienced by patients treated with tea-tree oil.


Assuntos
Acne Vulgar/tratamento farmacológico , Peróxido de Benzoíla/uso terapêutico , Óleos Voláteis/uso terapêutico , Óleos de Plantas/uso terapêutico , Árvores , Acne Vulgar/patologia , Adolescente , Adulto , Peróxido de Benzoíla/administração & dosagem , Peróxido de Benzoíla/efeitos adversos , Criança , Feminino , Géis , Humanos , Masculino , Óleos Voláteis/administração & dosagem , Óleos Voláteis/efeitos adversos , Óleos de Plantas/administração & dosagem , Óleos de Plantas/efeitos adversos , Estudos Prospectivos , Método Simples-Cego , Pele/patologia , Fatores de Tempo
20.
Opt Lett ; 13(10): 844-6, 1988 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-19746054

RESUMO

A suitable cross section incorporating material anisotropy is shown to give circular birefringence in a slowly spun monomode fiber. It is assumed that the fractional variation Deltan/n of the refractive index satisfies the weak guidance condition Deltan/n << 1 and that the period (or pitch) p of the spun fiber is large enough so that the fundamental modes remain effectively bound. Under these assumptions the magnitude of the circular birefringence can be calculated from solutions of the scalar wave equation and in any case lies between the limits (0, 4pi/p). The value is zero in the absence of material anisotropy. The required material anisotropy could be produced by stress implanted in the core.

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