Groundwater implications on methane emission from non-sewered sanitation systems in Nepal.

Non-sewered sanitation systems (NSSS) are identified as significant contributors of greenhouse gases (GHGs), primarily due to biological processes occurring within the containment systems. In unsealed or unlined containment systems like pit latrines, the emissions are influenced by moisture. This work quantified the GHG emission from unlined or unsealed containments prevalent in Nepal and compared it with sealed containment-like septic tanks, where the chances of groundwater (GW) inundation are low. The modeled GW data extracted from the secondary sources were validated with available national data. The emissions were quantified using the Intergovernmental Panel for Climate Change (IPCC) model for different ecological and provincial divisions of Nepal. Spatial representation for the results was done using the Geographical Information System (GIS) tool. The total methane (CH4) emission occurring from the various NSSS was determined to be 2618 Gg CO2 e per year which is almost twice the emission from the waste sector in 2011, as reported by the recent national communication submitted to the United Nations Framework Convention on Climate Change (UNFCC). Variation of the CH4 emission was found to be prominent in lowlands (Terai region) with total national emissions of 1329.37 Gg CO2e per year. The lowland has a shallow GW table that can easily inundate the unlined containments like pit latrines thus contributing to more anaerobic conditions which may lead to higher CH4 emissions compared to containments in mid and highlands. This study concludes that the GHG emissions occurring from NSSS are substantial and addressing these emissions can help fulfil the Nationally Determined Contributions (NDCs) in the waste sector.

Cross-cultural adaptation of Nepalese literacy and stigma of suicide scales (LOSS-SF-Nep and SOSS-SF-Nep) among Nepalese medical and nursing students.

INTRODUCTION: Nepal is a country in South-east Asia with high suicide. There is ongoing trend of emerging research on suicide from Nepal but there is lack of validated scale in measuring literacy or stigma. In the view of poor media reporting and large treatment gap, this study was conducted. All previous validation studies were done in non-Hindu populations. METHODS: A cross-sectional study was planned where the short forms of Nepalese literacy of suicide scale (LOSS-SF-Nep) and Stigma of Suicide Scale (SOSS-SF-Nep) were validated using standard procedure at a medical college in southern Nepal. Medical and nursing students of all batches were approached offline after successful pretesting. The psychometric properties of the scales were tested, and the statuses of literacy and stigma were assessed. Patient Health Questionnaire-9 and General Anxiety Disorder Scale-7 were used for revealing depression and generalized anxiety. RESULTS: Three hundred and nineteen Nepalese students participated and most of them were males, belonged to nuclear family, upper-middle socioeconomic status and represented 46 out of 77 districts of Nepal. The mean score of LOSS-SF-Nep was 6.36 ± 1.92 and literacy ranged from 37.9% to 89.7%. The deeper exposure to suicidal patients was associated with better literacy. Factor analysis of SOSS-SF-Nep revealed three subscales: stigmatization, isolation/depression, and normalization/glorification and had acceptable psychometric properties. Gender, occupation of head of the family, region and years of education, using mental health services, and depression were associated with variable literacy or stigma. CONCLUSION: Literacy and stigma scales were validated in Nepali, and SOSS factor structures were revealed with modified descriptors. The literacy and stigma levels in medical students were calculated for the first time in Nepal and Hindu majority population.

Field-based methods for measuring greenhouse gases emissions from on-site sanitation systems: A systematic review of published literature.

On-site sanitation systems (OSS) are a source of greenhouse gas (GHG) emissions. Although efforts have been made recently to measure and quantify emissions from septic tanks using various field-based methods, the vast majority of published literature reporting GHG emissions from OSS units (e.g., pits and tanks) is based on non-empirical evidence. This systematic review presents an overview and limitations of field-based methods used for the quantification of GHG emissions from OSS. Papers published in English were searched in three databases: Google Scholar, PubMed, and Directory of Articles and Journals. Peer-reviewed papers that reported field-based methods applied to containment units in OSS were included in this study. Only eight out of 2085 papers met the inclusion criteria with septic tanks as the sole technology reported and were thus, considered for the review. Most of the studies have been conducted in middle- and high-income countries. Field-based measurements of GHGs are conducted using a flux chamber (FC) and the most commonly used FC methods are (a) the modified simple static FC, (b) automated static FC, and (c) floating FC. Data reported in published studies do not provide sufficient information on the calibration and validation of the results from the FCs used. The complex FC designs, laborious fieldwork operations, and reliance on expensive, specialist equipment, suggest that such methods may not be suitable in Low and Middle-Income countries (LMICs), where resources and access to laboratory facilities are limited. Also, the complexity of pits and tank typology in LMICs (i.e., unstandardised designs and sizes) may be a challenge to the use of FCs with fixed dimensions and set operational conditions. The variation in the quantification methods and resulting emission rates among the studies indicates that gaps prevail in the use of existing methods. Therefore, there is still a need for a simple field-based, easily adaptable FC method with adequate calibration and validation that can help in reliably quantifying the emissions from different OSS in any LMICs.

Himalayan watersheds in Nepal record high soil erosion rates estimated using the RUSLE model and experimental erosion plots.

The rising unpredictability in the food supply chain in many parts of the world is related to soil loss and poor agricultural output. The Revised Universal Soil Loss Equation (RUSLE), widely used for estimating soil loss, was applied in the western mid-hills in Nepal, with steep slopes and fragile geology. This region is at high risk for rapid soil erosion and mass wasting. To estimate soil loss, this study utilized the RUSLE model with experimental erosion plots in the Aadhikhola and Tinahukhola watersheds, capturing real-time erosion in the field. The annual soil loss for the Aadhikhola watershed is estimated at ∼41.4 tons ha-1 yr-1. In contrast, in the Tinahukhola watershed, soil loss is low (∼24.1 tons ha-1 yr-1). Although annual rainfall showed an increasing trend in both watersheds, the change in soil loss was statistically insignificant. The high erosion rates from the experimental plots in both watersheds support the model outputs. Results from the experimental plots recorded the rate of soil erosion for different land use as: irrigated agricultural land > rainfed agricultural land > forests. The trends highlight the role of human activities in enhancing soil erosion in these mountainous terrains in terms of medium to long-term perspectives. Therefore, sustainable agriculture practices in these terrains must investigate alternate ways to decrease soil erosion to support people's livelihoods.

Lichens as spatially transferable bioindicators for monitoring nitrogen pollution.

Excess nitrogen is a pollutant and global problem that harms ecosystems and can severely affect human health. Pollutant nitrogen is becoming more widespread and intensifying in the tropics. There is thus a requirement to develop nitrogen biomonitoring for spatial mapping and trend analysis of tropical biodiversity and ecosystems. In temperate and boreal zones, multiple bioindicators for nitrogen pollution have been developed, with lichen epiphytes among the most sensitive and widely applied. However, the state of our current knowledge on bioindicators is geographically biased, with extensive research effort focused on bioindicators in the temperate and boreal zones. The development of lichen bioindicators in the tropics is further weakened by incomplete taxonomic and ecological knowledge. In this study we performed a literature review and meta-analysis, attempting to identify characteristics of lichens that offer transferability of bioindication into tropical regions. This transferability must overcome the different species pools between source information - drawing on extensive research effort in the temperate and boreal zone - and tropical ecosystems. Focussing on ammonia concentration as the nitrogen pollutant, we identify a set of morphological traits and taxonomic relationships that cause lichen epiphytes to be more sensitive, or more resistant to this excess nitrogen. We perform an independent test of our bioindicator scheme and offer recommendations for its application and future research in the tropics.

Fish and macroinvertebrate assemblages reveal extensive degradation of the world's rivers.

Rivers suffer from multiple stressors acting simultaneously on their biota, but the consequences are poorly quantified at the global scale. We evaluated the biological condition of rivers globally, including the largest proportion of countries from the Global South published to date. We gathered macroinvertebrate- and fish-based assessments from 72,275 and 37,676 sites, respectively, from 64 study regions across six continents and 45 nations. Because assessments were based on differing methods, different systems were consolidated into a 3-class system: Good, Impaired, or Severely Impaired, following common guidelines. The proportion of sites in each class by study area was calculated and each region was assigned a Köppen-Geiger climate type, Human Footprint score (addressing landscape alterations), Human Development Index (HDI) score (addressing social welfare), % rivers with good ambient water quality, % protected freshwater key biodiversity areas; and % of forest area net change rate. We found that 50% of macroinvertebrate sites and 42% of fish sites were in Good condition, whereas 21% and 29% were Severely Impaired, respectively. The poorest biological conditions occurred in Arid and Equatorial climates and the best conditions occurred in Snow climates. Severely Impaired conditions were associated (Pearson correlation coefficient) with higher HDI scores, poorer physico-chemical water quality, and lower proportions of protected freshwater areas. Good biological conditions were associated with good water quality and increased forested areas. It is essential to implement statutory bioassessment programs in Asian, African, and South American countries, and continue them in Oceania, Europe, and North America. There is a need to invest in assessments based on fish, as there is less information globally and fish were strong indicators of degradation. Our study highlights a need to increase the extent and number of protected river catchments, preserve and restore natural forested areas in the catchments, treat wastewater discharges, and improve river connectivity.

Inactivation of mouse transmembrane prolyl 4-hydroxylase increases blood brain barrier permeability and ischemia-induced cerebral neuroinflammation.

Hypoxia-inducible factor prolyl 4-hydroxylases (HIF-P4Hs) regulate the hypoxic induction of >300 genes required for survival and adaptation under oxygen deprivation. Inhibition of HIF-P4H-2 has been shown to be protective in focal cerebral ischemia rodent models, while that of HIF-P4H-1 has no effects and inactivation of HIF-P4H-3 has adverse effects. A transmembrane prolyl 4-hydroxylase (P4H-TM) is highly expressed in the brain and contributes to the regulation of HIF, but the outcome of its inhibition on stroke is yet unknown. To study this, we subjected WT and P4htm-/- mice to permanent middle cerebral artery occlusion (pMCAO). Lack of P4H-TM had no effect on lesion size following pMCAO, but increased inflammatory microgliosis and neutrophil infiltration was observed in the P4htm-/- cortex. Furthermore, both the permeability of blood brain barrier and ultrastructure of cerebral tight junctions were compromised in P4htm-/- mice. At the molecular level, P4H-TM deficiency led to increased expression of proinflammatory genes and robust activation of protein kinases in the cortex, while expression of tight junction proteins and the neuroprotective growth factors erythropoietin and vascular endothelial growth factor was reduced. Our data provide the first evidence that P4H-TM inactivation has no protective effect on infarct size and increases inflammatory microgliosis and neutrophil infiltration in the cortex at early stage after pMCAO. When considering HIF-P4H inhibitors as potential therapeutics in stroke, the current data support that isoenzyme-selective inhibitors that do not target P4H-TM or HIF-P4H-3 would be preferred.

Infrastructure alone cannot ensure resilience to weather events in drinking water supplies.

Climate resilient water supplies are those that provide access to drinking water that is sustained through seasons and through extreme events, and where good water quality is also sustained. While surface and groundwater quality are widely understood to vary with rainfall, there is a gap in the evidence on the impact of weather and extremes in rainfall and temperature on drinking water quality, and the role of changes in water system management. A three-country (Bangladesh, Nepal and Tanzania) observational field study tracked 2353 households clustered around 685 water sources across seven different geographies over 14 months. Water quality (E. coli) data was modelled using GEE to account for clustering effects and repeated measures at households. All types of infrastructure were vulnerable to changes in weather, with differences varying between geographies; protected boreholes provided the greatest protection at the point of collection (PoC). Water quality at the point of use (PoU) was vulnerable to changes in weather, through changes in PoC water quality as well as changes in management behaviours, such as safe storage, treatment and cleaning. This is the first study to demonstrate the impact of rainfall and temperature extremes on water quality at the PoC, and the role that weather has on PoU water quality via management behaviours. Climate resilience for water supplies needs to consider the infrastructure as well as the management decisions that are taking place at a community and household level.

Transmembrane Prolyl 4-Hydroxylase is a Novel Regulator of Calcium Signaling in Astrocytes.

Prolyl 4-hydroxylases (P4Hs) have vital roles in regulating collagen synthesis and hypoxia response. A transmembrane P4H (P4H-TM) is a recently identified member of the family. Biallelic loss of function P4H-TM mutations cause a severe autosomal recessive intellectual disability syndrome in humans, but functions of P4H-TM are essentially unknown at cellular level. Our microarray data on P4h-tm-/- mouse cortexes where P4H-TM is abundantly expressed indicated expression changes in genes involved in calcium signaling and expression of several calcium sequestering ATPases was upregulated in P4h-tm-/- primary mouse astrocytes. Cytosolic and intraorganellar calcium imaging of P4h-tm-/- cells revealed that receptor-operated calcium entry (ROCE) and store-operated calcium entry (SOCE) and calcium re-uptake by mitochondria were compromised. HIF1, but not HIF2, was found to be a key mediator of the P4H-TM effect on calcium signaling. Furthermore, total internal reflection fluorescence (TIRF) imaging showed that calcium agonist-induced gliotransmission was attenuated in P4h-tm-/- astrocytes. This phenotype was accompanied by redistribution of mitochondria from distal processes to central parts of the cell body and decreased intracellular ATP content. Our data show that P4H-TM is a novel regulator of calcium dynamics and gliotransmission.

Nutritional and health status of children 15 months after integrated school garden, nutrition, and water, sanitation and hygiene interventions: a cluster-randomised controlled trial in Nepal.

BACKGROUND: It has been suggested that specific interventions delivered through the education sector in low- and middle-income countries might improve children's health and wellbeing. This cluster-randomised controlled trial aimed to evaluate the effects of a school garden programme and complementary nutrition, and water, sanitation and hygiene (WASH) interventions on children's health and nutritional status in two districts of Nepal. METHODS: The trial included 682 children aged 8-17 years from 12 schools. The schools were randomly allocated to one of three interventions: (a) school garden programme (SG; 4 schools, n = 172 children); (b) school garden programme with complementary WASH, health and nutrition interventions (SG+; 4 schools, n = 197 children); and (c) no specific intervention (control; 4 schools, n = 313 children). The same field and laboratory procedures were employed at the baseline (March 2015) and end-line (June 2016) surveys. Questionnaires were administered to evaluate WASH conditions at schools and households. Water quality was assessed using a Delagua kit. Dietary intake was determined using food frequency and 24-h recall questionnaire. Haemoglobin levels were measured using HemoCue digital device and used as a proxy for anaemia. Stool samples were subjected to a suite of copro-microscopic diagnostic methods for detection of intestinal protozoa and helminths. The changes in key indicators between the baseline and end-line surveys were analysed by mixed logistic and linear regression models. RESULTS: Stunting was slightly lowered in SG+ (19.9 to 18.3%; p = 0.92) and in the control (19.7 to 18.9%). Anaemia slightly decreased in SG+ (33.0 to 32.0%; p < 0.01) and markedly increased in the control (22.7 to 41.3%; p < 0.01), a minor decline was found in the control (43.9 to 42.4%). Handwashing with soap before eating strongly increased in SG+ (from 74.1 to 96.9%; p = 0.01, compared to control where only a slight increase was observed from 78.0 to 84.0%). A similar observation was made for handwashing after defecation (increase from 77.2 to 99.0% in SG+ versus 78.0 to 91.9% in control, p = 0.15). CONCLUSIONS: An integrated intervention consisting of school garden, WASH, nutrition and health components (SG+) increased children's fruit and vegetable consumption, decreased intestinal parasitic infections and improved hygiene behaviours. TRIAL REGISTRATION: ISRCTN17968589 (date assigned: 17 July 2015).

Intestinal parasite infections and associated risk factors among schoolchildren in Dolakha and Ramechhap districts, Nepal: a cross-sectional study.

BACKGROUND: Infections with soil-transmitted helminths and pathogenic intestinal protozoa pose a considerable public health burden, particularly in low- and middle-income countries, including Nepal. We assessed the extent of intestinal parasite infections among schoolchildren in two districts of Nepal and determined underlying risk factors. METHODS: A cross-sectional survey was conducted between March and May 2015 in the districts of Dolakha and Ramechhap, Nepal. A total of 708 children, aged 8-16 years from 16 purposively selected schools, were enrolled. Each child provided a single stool sample that was subjected to a suite of copro-microscopic diagnoses for intestinal protozoa and helminths. Drinking water samples from different sources at schools (n = 29), community places (n = 43) and households (n = 562) were analysed for contamination with thermotolerant coliforms (TTC). A questionnaire was administered to determine individual- and household-level risk factors of intestinal parasite infections. Self-reported symptoms were assessed and a clinical examination was undertaken by a physician. Haemoglobin was measured and used as a proxy for anaemia. Mixed logistic regression models were applied to investigate associations. RESULTS: The overall prevalence of intestinal parasite infections was 39.7%. Trichuris trichiura (30.9%), Giardia intestinalis (30.5%) and hookworm (30.2%) were the predominant intestinal parasite infections. Children from households lacking soap for handwashing were at higher odds of intestinal parasite infections than children who had soap [adjusted odds ratio (aOR) 1.81; 95% confidence interval (CI): 1.13-2.89; P = 0.01]. Children from households without freely roaming domestic animals showed lower odds of G. intestinalis compared to children from households with freely roaming animals (aOR 0.52; 95% CI: 0.33-0.83; P = 0.01). One out of three (31.0%) children suffered from fever and 22.4% had watery diarrhoea within a two-week recall period. Anaemia was diagnosed in 23.6% of the children. Water contamination with TTC showed no clear association with intestinal parasite infection. CONCLUSIONS: Intestinal parasites are common among schoolchildren in the two surveyed districts of Nepal. An important risk factor was lack of soap for handwashing. Our findings call for efforts to control intestinal parasite infection and emphasis should be placed on improvements in water, sanitation and hygiene interventions. TRIAL REGISTRATION: ISRCTN17968589 (date assigned: 17 July 2015).

Water Quality, Sanitation, and Hygiene Conditions in Schools and Households in Dolakha and Ramechhap Districts, Nepal: Results from A Cross-Sectional Survey.

This study assessed drinking water quality, sanitation, and hygiene (WASH) conditions among 708 schoolchildren and 562 households in Dolakha and Ramechhap districts of Nepal. Cross-sectional surveys were carried out in March and June 2015. A Delagua water quality testing kit was employed on 634 water samples obtained from 16 purposively selected schools, 40 community water sources, and 562 households to examine water quality. A flame atomic absorption spectrophotometer was used to test lead and arsenic content of the same samples. Additionally, a questionnaire survey was conducted to obtain WASH predictors. A total of 75% of school drinking water source samples and 76.9% point-of-use samples (water bottles) at schools, 39.5% water source samples in the community, and 27.4% point-of-use samples at household levels were contaminated with thermo-tolerant coliforms. The values of water samples for pH (6.8-7.6), free and total residual chlorine (0.1-0.5 mg/L), mean lead concentration (0.01 mg/L), and mean arsenic concentration (0.05 mg/L) were within national drinking water quality standards. The presence of domestic animals roaming inside schoolchildren's homes was significantly associated with drinking water contamination (adjusted odds ratio: 1.64; 95% confidence interval: 1.08-2.50; p = 0.02). Our findings call for an improvement of WASH conditions at the unit of school, households, and communities.

Complementary school garden, nutrition, water, sanitation and hygiene interventions to improve children's nutrition and health status in Burkina Faso and Nepal: a study protocol.

BACKGROUND: Malnutrition and intestinal parasitic infections are common among children in Burkina Faso and Nepal. However, specific health-related data in school-aged children in these two countries are scarce. In the frame of a larger multi-stakeholder project entitled "Vegetables go to School: Improving Nutrition through Agricultural Diversification" (VgtS), a study has been designed with the objectives to: (i) describe schoolchildren's health status in Burkina Faso and Nepal; and to (ii) provide an evidence-base for programme decisions on the relevance of complementary school garden, nutrition, water, sanitation and hygiene (WASH) interventions. METHODS/DESIGN: The studies will be conducted in the Centre Ouest and the Plateau Central regions of Burkina Faso and the Dolakha and Ramechhap districts of Nepal. Data will be collected and combined at the level of schools, children and their households. A range of indicators will be used to examine nutritional status, intestinal parasitic infections and WASH conditions in 24 schools among 1144 children aged 8-14 years at baseline and a 1-year follow-up. The studies are designed as cluster randomised trials and the schools will be assigned to two core study arms: (i) the 'complementary school garden, nutrition and WASH intervention' arm; and the (ii) 'control' arm with no interventions. Children will be subjected to parasitological examinations using stool and urine samples and to quality-controlled anthropometric and haemoglobin measurements. Drinking water will be assessed for contamination with coliform bacteria and faecal streptococci. A questionnaire survey on nutritional and health knowledge, attitudes and practices (KAP) will be administered to children and their caregivers, also assessing socioeconomic, food-security and WASH conditions at household level. Focus group and key-informant interviews on children's nutrition and hygiene perceptions and behaviours will be conducted with their caregivers and school personnel. DISCUSSION: The studies will contribute to fill a data gap on school-aged children in Burkina Faso and Nepal. The data collected will also serve to inform the design of school-based interventions and will contribute to deepen the understanding of potential effects of these interventions to improve schoolchildren's health in resource-constrained settings. Key findings will be used to provide guidance for the implementation of health policies at the school level in Burkina Faso and Nepal. TRIAL REGISTRATION: ISRCTN30840 (date assigned: 17 July 2015).

Mercury concentrations in commercial fish species of Lake Phewa, Nepal.

Mercury (Hg) concentrations in four commercial fish species (Tilapia Oreochromis niloticus, Spiny Eel Mastacembelus armatus, African catfish Clarias gariepinus, and Sahar Tor putitora), were investigated in Lake Phewa, Nepal. Mean values of total mercury (THg mg kg(-1), ww) in these fishes were 0.02, 0.07, 0.05, and 0.12 respectively. Methylmercury contributed 82 % of THg. The lowest value was detected in O. niloticus, an exclusive plant feeder. The biomagnification rate of Hg through the fish community was 0.041 per δ(15)N (‰). The present investigation produced an important baseline data of Hg pollution in the fish community in this region.

Knowledge, attitude and practices of pesticide use and acetylcholinesterase depression among farm workers in Nepal.

Assessing erythrocyte acetylcholinesterase (AChE) activity in farm workers across agricultural seasons can be used to monitor risks of pesticide exposure. We surveyed a total of 403 households in Nepal and adopted the Test-mate ChE Cholinesterase Test System to monitor AChE activity across season on the 127 individuals of the sampled households. The study aims to (i) document knowledge and practices of pesticide use among farmers and (ii) present the relationship between farmers' reported acute health symptoms and erythrocyte acetylcholinesterase depression. We found low levels of pesticide use hygiene and high levels of individuals' knowledge on the local environmental impacts of pesticide use. Safety measures taken against potential risks of pesticides exposure were inadequate. Exposure to organophosphates significantly reduced AChE activity across season, but was not sufficient enough to claim clinical symptoms whereas exposure to the pyrethroid insecticides and fungicides were sufficient enough to claim acute symptoms of poisoning.

Use of Monte Carlo simulations for propagation of light in biomedical tissues.

In problems relating to light propagation in biomedical tissues, the tissue is generally modeled as a turbid medium and Monte Carlo (MC) simulation is employed to compute quantities such as diffuse reflectance, fluence, and transmittance. Two prescriptions are available in the literature for MC simulations. The first prescription considers all input quantities, including phase function, as an average over the particle size distribution, and the second prescription considers the phase function of each scatterer individually. The two prescriptions have been compared and contrasted in this paper for a given soft tissue model. It is demonstrated that, in general, the two recipes do not yield identical results. The source of this disagreement has been traced.

Atypical clinical presentation of mucopolysaccharidosis type II (Hunter syndrome): a case report.

INTRODUCTION: We present a very rare case of mucopolysaccharidosis with atypical presentation such as mild mental retardation, an acrocephalic head and no corneal clouding. The purpose of presenting this case is to highlight the distinctive manifestation of mucopolysaccharidosis type II (Hunter syndrome). CASE PRESENTATION: A 10-year-old East Asian boy presented with abdominal distension of five years' duration and complained of shortness of breath on and off for the same period. On examination his head was large and his head circumference was 54.5 cm. His neck was short, he had coarse facial features, a depressed nasal bridge and small stubby fingers with flexion of distal interphalangeal joints, and a low arched palate was observed. There was mild mental retardation. CONCLUSION: Based on clinical findings and radiological features it is possible to diagnose a case of mucopolysaccharidosis.Careful and systemic approach is needed to accurately diagnose the exact type as enzymatic studies are not available in most centers.

Developing a sustainable agro-system for central Nepal using reduced tillage and straw mulching.

In Nepal, soil erosion under maize (Zea mays) agro-ecosystems is most critical during the pre-monsoon season. Very few field experiments have been conducted on reduced tillage and rice straw (Oryza sativa) mulching, although these conservation approaches have been recommended. Thus, a five replicate field experiment was established in 2001 at Kathmandu University (1500 m above sea level) on land with 18% slope to evaluate the efficiency of reduced tillage and mulching on soil and nutrient losses and maize yield. The results showed non-significant differences among conservation approaches on runoff and maize yield. Mulching and reduced tillage significantly lowered annual and pre-monsoon soil and nutrient losses compared to conventional tillage. Soil organic matter (SOM) and nitrogen losses associated with eroded sediment were significantly higher in conventional tillage. However, due to limited availability and high opportunity cost of rice straw, reduced tillage would be a better option for soil and nutrient conservation without sacrificing economic yield in upland maize agro-ecosystems.

Validity of a modified Born approximation for a pulsed plane wave in acoustic scattering problems.

The validity domain of a modified Born approximation (MBA) has been examined for the scattering of a pulsed plane wave (PPW). This new approximation has been compared with exact results and also with the conventional Born approximation (BA). Comparisons have been made for the scattering by a homogeneous sphere. Error charts have been presented for various scatterer sizes and acoustic properties for forward as well as back scattering. The pulse width has also been varied. Our study shows that the modified Born approximation is generally preferable to the conventional Born approximation in the forward direction. In the backward direction both approximations have a similar kind of validity domain. These observations are important in view of the fact that the Born approximation has been widely used in acoustic scattering problems.