Vector abundance and species composition of Anopheles mosquitoin Central Region and Central West Highlands, Viet Nam

Malaria is a major cause of morbidity and mortality in Viet Nam. In 2008, World Health Organization reported an estimated value of 243 million cases with a mortality of about 863 thousand in the world. Malaria transmission in the Central Region and Central West Highlands of Viet Nam is known to be holoendemic and perennial. High humidity (80%) and a high mean temperature of 25°C in this area favour the bionomics of the principal malaria vectors. Vector control is a major component of the Global Malaria Control Strategy and still remains the most generally effective measure to prevent malaria transmission. Successful application of vector control measures requires the understanding of the bionomics of Anopheles species responsible for malaria transmission, including correct and precise identification of the target species and its distribution.This study was conducted to provide information on the vector abundance and species composition of Anopheles mosquito at Quang Binh, Binh Đinh, Khanh Hoa, Ninh Thuan, Gia Lai, Dak Lak ofCentral Region and Central West Highlands of Viet Nam. A total of 18 Anopheles species were collected in these provinces, therein, the 2main vectors are An. minimus and An. dirus, and the 3 secondary vectors are An. aconitus, An. jeyporiensis, An. maculatus. An. dirus and An. minimus species are present in most of the studied communes in 6 provinces, An. aconitus, An. jeyporiensis and An. maculatusare present in Binh Dinh, Ninh Thuan and Gia Lai provinces, whileAn. jeyporiensisdoes not seem to be found in the other provinces

Study of the nat^{nat}Sm(γ,xn)143m,g(\gamma ,xn)^{143m,g}Sm Reactions Induced by Bremsstrahlung with End-point Energies Just above GDR Region

We investigate the energy dependence of the isomeric yield ratios for the $^{nat}$Sm$(\gamma ,xn)^{143m,g}$Sm reactions with bremsstrahlung energies of 40-, 45-, and 50-MeV, just above the giant dipole resonance (GDR) region by the off-line $\gamma$-ray spectrometric method. The bremsstrahlung photons were produced from the 100 MeV electron linear accelerator (linac) at the Pohang accelerator laboratory (PAL), Pohang, Korea. In order to improve the accuracy of the experimental results the necessary corrections were made. The present results are compared with similar literature data of the $^{nat}$Sm($\gamma$,xn)$^{143m,g}$Sm reactions measured at various photon energies and of the $^{nat}$Sm(n,2n)$^{143m,g}$Sm reaction induced by 14 MeV neutrons in order to examine the effects of an excitation energy and an input angular momentum

Integrated Cross Sections of the Photo-Neutron Reactions Induced on 197^{197}Au with 60 MeV\text{MeV} Bremsstrahlung

Abstract. Seven photo-neutron reactions 197Au(γ,xn)197-xAu (with x=1-7) produced by the bremsstrahlung end-point energy of 60 MeV were identified. In this work, we focus on the measurement of integrated sections. Experiments were carried out based on the activation method in combination with off-line gamma-ray spectrometric technique. The integrated cross sections of the investigated reactions were determined relative to that of the monitoring reaction 197Au(γ,n)196Au. To validate the experimental results, theoretical predictions were also made using the computer code TALYS 1.9. The current integrated cross-sections of the 197Au(γ,xn)197-xAu reactions with 60 MeV bremsstrahlung end point energy are measured for the first time

Cross Sections for the nat^{nat}Zr(p,xn)89,90(p,xn)^{89,90}Nb Reactions Induced by 27.7 MeV Protons

The cross-sections for the formation of $^{89}$Nb and  $^{90}$Nb radionuclides in proton induced nuclear reactions on zirconium  were measured by using the well known activation method. The natural  zirconium ($^{nat}$Zr) target and copper ($^{nat}$Cu) monitor foils were  irradiated by 27.7 MeV proton beam at the MC50 Cyclotron of the Korea  Institute of Radiological and Medical Science (KIRAMS), Korea. The induced  gamma activities of the reaction products were measured by a coaxial high  purity germanium (HPGe) detector coupled to a PC-based multichannel  analyzer. The obtained cross sections for each nuclide are compared with  those existing in literature and with the theoretical cross sections  calculated by the TALYS - 1.4 code

Study of Multiple Photoneutron Reactions on 197Au Induced by 2.5 GeV Bremsstrahlung

We identified eight radionuclides $^{196}$Au, $^{195}$Au, $^{194}$Au, $^{193}$Au, $^{192}$Au, $^{191}$Au, $^{190}$Au, $^{189}$Au formed via the multiple photoneutron reactions $^{197}$Au$(\gamma ,kn)^{197 - k}$Au with 2.5 GeV\break bremsstrahlung. The yields of radionuclides that decay by emitting $\gamma$-ray were measured using high purity germanium (HPGe) detector coupled to a PC-based multichannel analyzer. In order to improve the accuracy of the experimental results the necessary corrections were made. The obtained results are compared with reference data and the variations of the $^{197}$Au($\gamma$,kn)$^{197 - k}$Au reaction yields according to incident bremsstrahlung energy and neutron multiplicity are also discussed

Yield Ratios of the Isomeric Pair 179m,g^{179m,g}W Produced in the nat^{nat}W(g,xn)179m,g^{179m,g}W Reactions with 50-65 MeV Bremsstrahlung

In this work we present the yield ratios of the $^{179m,g}$W isomeric pair produced in the photonuclear reactions $^{nat}$W(g,xn)$^{179m,g}$W  with bremsstrahlung end-point energies of 50-, 55-, 60-, and 65-MeV. The measurements were carried out by the induced activity method in combination with direct gamma-ray spectrometry. The measured activities were corrected for overlapping gamma-ray peaks, self-absorption of low energy gamma-rays and true coincidence summing effects. The present results  are measured for the first time with bremsstrahlung end-point energies beyond the giant dipole resonance region. The obtained results are discussed with respect to the incident bremsstrahlung energies and reaction channel effect

The role of rice fields, fish ponds and water canals for transmission of fish-borne zoonotic trematodes in aquaculture ponds in Nam Dinh Province, Vietnam

BACKGROUND: Fish-borne zoonotic trematodes (FZT), such as Clonorchis sinensis, Opistorchis viverini (Opisthorchiidae) and intestinal trematodes of the family Heterophyidae, constitute a public health hazard in Vietnam and infections with these trematodes has been linked to consumption of raw or undercooked fish from aquaculture. The FZT transmission pathways, however, are more complicated than just the presence of intermediate snail hosts in aquaculture ponds as ponds may exchange water with surrounding habitats such as rice fields and irrigation canals and thereby these surrounding habitats may be a source of snails and cercariae and contribute to FZT infection in cultured fish. METHODS: This is a longitudinal descriptive study on selected farms (n = 30) in Nam Dinh Province which is endemic for FZT. At each farm, we sampled one pond, a small irrigation canal used to supply the pond with water, and a nearby rice field. At each of these three sites, we estimated the density of the FZT intermediate snail hosts and determined their trematode infection status. Comparative analysis was performed for the prevalence and density of FZT infections in fish and snails. RESULTS: Species of the Thiaridae, and most notably Melanoides tuberculata, the most important host species for FZT belonging to the Heterophyidae, were particularly abundant in ponds and small canals, i.e. M. tuberculata was found in 27 ponds and 13 small canals. Bithynia fuchsiana, a potential host for both Heterophyidae and Opisthorchiidae, was rarely found in fish ponds but common in rice fields. A total of 12 types of cercariae were found in the snails and pleurolophocercous cercariae, primarily FZT, constituted about 40 % of all cercarial infections. The fish species cultured were mainly carp species and Haplorchis pumilio was the dominating trematode species infecting fish. Clonorchis spp. were not recorded in any of the ponds. FZT transmission to fish was intense during the summer period (May-June to November) but less intense during the winter months (December-January) partly because cercarial emergence ceases due to the low temperature. CONCLUSION: Our findings highlight the complexity of FZT transmission within aquaculture farm settings and suggest that efforts to control these infections must take a holistic approach using interventions against all stages of the transmission cycle