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We have studied dispersion of surface plasmon polaritons (SPPs) in the Kretschmann geometry (prism/Ag/dye-doped polymer) in weak, intermediate, and ultra-strong exciton-plasmon coupling regimes. The dispersion curves obtained in the reflection experiment were in good agreement with the simple model predictions at small concentrations of dye (Rhodamine 590, Rh590) in the polymer (Poly(methyl methacrylate), PMMA). At the same time, highly unusual multi-segment "staircase-like" dispersion curves were observed at extra-large dye concentrations, also in agreement with the simple theoretical model predicting large, small, and negative group velocities featured by different polariton branches. In a separate experiment, we measured angular dependent emission of Rh590 dye and obtained the dispersion curves consisting of two branches, one nearly resembling the SPP dispersion found in reflection and the second one almost horizontal. The results of our study pave the road to unparalleled fundamental science and future applications of weak and strong light-matter interactions.

We explore a possibility to control magnetic dipole emission with plasmonic cavities, placing Eu 3+ emitters inside profile-modulated metal-dielectric-metal structures. Significant variations in the branching ratio of the magnetic and electric dipole transitions are observed as the function of the thickness of the intermediate layer. The experimental results are confirmed with numerical simulations which account for cavity and gap plasmon resonances and predict modifications in the spontaneous emission spectrum as the function of the gap size and a strong directionality of the emission for small thicknesses of the intermediate layer. The implications of having a competition between electric and magnetic dipole relaxation channels in Eu 3+ are discussed.

In the context of limited effectiveness of iron supplementation programs, intermittent iron supplementation is currently under debate as a possible alternative strategy that may enhance the effectiveness of operational programs. This field-based trial assessed the outcome of twice weekly iron supplementation compared to daily in Pakistan. A double-blind, randomized, clinical trial was conducted in Northern Pakistan. Anemic pregnant women (n = 191) were assigned to receive daily (200 mg ferrous sulfate) or twice weekly (2 x 200 mg ferrous sulfate) iron supplementation. Hemoglobin was measured at baseline and at 4-wk intervals for up to 12 wk. Serum ferritin was measured at baseline and 8 or 12 wk. Analysis was by intention to treat. The two groups did not differ in age, parity, sociodemographic characteristics, hemoglobin or serum ferritin concentrations at baseline. Women who received iron daily had a greater rise in hemoglobin compared with women who received iron twice weekly (17.8 +/- 1.8 vs. 3.8 +/- 1.2 g/L, P < 0.001). The serum ferritin concentrations increased by 17.7 +/- 3.9 microgram/L (P < 0.001) in the daily supplemented group and did not change in the twice weekly group. Daily iron supplementation remained superior to twice weekly supplementation after controlling initial hemoglobin Z-scores and duration of treatment. The body mass index (BMI) modified the effect of daily versus twice weekly iron supplementation. For every unit increase in BMI, the difference between the two treatment groups was reduced by 0.0014 (final hemoglobin Z-score; P = 0.027). We recommend continuation of daily iron supplementation as opposed to intermittent iron supplementation in pregnant women in developing countries.

Snake bite remains a common injury in endemic areas of Pakistan. A facility based observational study was undertaken to ascertain the incidence of snake bite, its mortality and the management in public health facilities located in the Thar Desert of Province of Sindh, Pakistan. A total of 771 cases of snake bite were reported to seven randomly selected health facilities during a one-year period. Most (75%) occurred during nighttime in summer, affecting primarily males (70%) who were bitten mostly on the lower extremities (83%). Five hundred and thirteen bites (66%) were identified as poisonous and 4 deaths were reported. Seventy two percent of patients reached the health facility within 24 hours and twenty percent within 6 hours and of being bitten. Snake bite remains an important problem in endemic areas of Pakistan. People do seek assistance at public health facilities, where appropriate treatment including anti snake venom is given.

In order to identify and characterise the organisms responsible for Cutaneous Leishmaniasis, parasites were isolated from active lesions, grown in-vitro cultures and identified by iso-enzyme characterisation. Thirteen isolates from different patients were typed as L. tropica. Seven of these isolates were from Afghan refugees encamped in the suburbs of Islamabad, 3 were from patients in Multan, 1 was from a patient from Azad Jammu and Kashmir and 1 was from Besham (Swat, NWFP). The study confirms the presence of anthroponotic Cutaneous Leishamaniasis caused by L. Tropica in Pakistan.

During December 1993 and in the first three months of 1994, an explosive water-borne epidemic of hepatitis E virus (HEV) occurred in two sectors of Islamabad, Pakistan. In a survey of a population of 36,705 individuals, a total of 3,827 cases of acute icteric hepatitis were recorded with an overall attack rate (AR) of 10.4%. The etiologic role of HEV in the epidemic was proven by demonstrating anti-HEV IgG and HEV IgM in the tested serum samples. The water-borne nature of the epidemic was suggested by a study of the case distribution according to water supply. Prior to the epidemic, there had been an operational breakdown in a water treatment plant that distributed water to the affected areas while transforming its purification system from slow sand to rapid sand filtration. The primary source of water for the plant was derived from a heavily contaminated stream. The highest AR (16.3%) was observed in the areas where the source of drinking water was exclusively from the purification plant, followed by ARs of 12.4% and 5.3% for those receiving 50% and 30% or less of their water supply from the treatment plant, respectively, while the lowest AR (1.8%) was observed in the neighboring areas that did not receive water from this source. The AR was significantly higher in the group 11-30 years of age (15.3%) as compared with children less than 11 years of age (1.4%) and also relative to the group greater than 30 years of age (10.5%). The AR among the 162 recorded pregnant females was 21.6%, which was higher than that found among nonpregnant females of child-bearing age (10.9%). All four reported adult deaths occurred among females in their third trimester of pregnancy with a case fatality rate of 11.4%, while the other four fatal cases were newborn infants of mothers with acute icteric hepatitis. Although the aggregation of cases within households was significantly related to family size, the temporal relationship between cases in households with two or more cases revealed that 83.7% of 1,463 presumed secondary cases occurred within one month of the first case in the same household, which is not suggestive of person-to-person transmission of disease. The termination of providing water from the source was effected, which was followed by an apparent decrease in cases.

Indirect Immunofluorescence Antibody (IFA) Technique was employed, for field detection of malarial parasite. The technique involved application of homologous antigen slides of Plasmodium falciparum and P. vivax prepared in the field conditions. Serological study, simultaneously using P. falciparum and P. vivax antigens, brought out a clearer picture of distribution and role of the parasite species in the epidemiology of the disease in the area studied. The survey supported the contention of persistence of transmission of malaria in Gujranwala District.

Between January '85 and August '87, 22 cases of VL were seen at National Institute of Health, Islamabad. Three (14.6%) came from the previously known endemic region of Gilgit, 15 (68.1%) from different localities in Azad Jammu and Kashmir (AJ&K), and 4 (17.3%) from neighbouring foci in NWFP and Punjab. Mean age of the patients was 4.2 years, (Range, 10 months to 57 years) median 2.5 years and mode 2 years. High levels of Leishmania antibodies were detected by Indirect Immunofluorescent Antibody Technique (IFAT) in all cases. Leishmania were isolated from bone marrow aspirates of 2 patients and isoenzyme characterization performed in one of these, the organism was typed as Leishmania infantum sensu stricto. Sera from 289 children residing in 5 endemic localities in AJ&K was tested for Leishmania specific antibodies by IFAT and low levels of these antibodies were detected in 15.4% of the cases.