Transient Flow Routing in Channel Networks

The formulation of a mathematical model to predict transient flows in hydraulic networks is presented. The network formulation consists of breaking the network into a series of connected reaches; reducing the finite difference equations for each reach into two "reach" equations; forming an exterior matrix consisting of the reach equations, external boundary conditions, and interior compatibility conditions; solving the external matrix for the end values of discharge and water surface elevation for all reaches and back-substituting for all interior values. Examples presented include the James River, USA, estuary model (twenty-four nodes and twenty-six reaches), the Cork Harbour, Ireland, estuary (thirteen-reach, double-looped network), and the Rio Bayamon basin, Puerto Rico. Results are very satisfactory when compared to known data

Some aspects of aerated open-channel flow at shallow depths and low velocities

This study is concerned with the effect of entrained air bubbles on the open-channel hydraulics of water flowing at low velocities. The air bubbles are introduced into the flowing water by injecting diffused compressed air along the channel bottom. The variations of the velocity profile and velocity distribution energy coefficient of aerated and nonaerated flow are discussed. Empirical equations have been determined for the air concentration and increased depth of flow or bulking of the aerated open-channel flow. The investigation revealed a significant increase in the Manning roughness coefficient and the related Darcy friction factor for aerated flow relative to those for nonaerated open-channel flow. Empirical equations are presented which relate the Manning roughness coefficient and Darcy friction factor of aerated flow to the depth, velocity, and Reynolds number of nonaerated open-channel flow. The results of this investigation are valid only within the range of depths and velocities studied and are further restricted to the geometry and pressure range of the particular air diffuser system utilized in the study --Abstract, page ii

Epidemiology of Plasmodium knowlesi malaria in north-east Sabah, Malaysia: family clusters and wide age distribution

BackgroundThe simian parasite Plasmodium knowlesi is a common cause of human malaria in Malaysian Borneo, with a particularly high incidence in Kudat, Sabah. Little is known however about the epidemiology in this substantially deforested region. MethodsMalaria microscopy records at Kudat District Hospital were retrospectively reviewed from January 2009-November 2011. Demographics, and PCR results if available, were recorded for each positive result. Medical records were reviewed for patients suspected of representing family clusters, and families contacted for further information. Rainfall data were obtained from the Malaysian Meteorological Department. Results“Plasmodium malariae” mixed or mono-infection was diagnosed by microscopy in 517/653 (79%) patients. Of these, PCR was performed in 445 (86%) and was positive for P. knowlesi mono-infection in 339 (76%). Patients with knowlesi malaria demonstrated a wide age distribution (median 33, IQR 20–50, range 0.7-89 years) with P. knowlesi predominating in all age groups except those <5 years old, where numbers approximated those of Plasmodium falciparum and Plasmodium vivax. Two contemporaneous family clusters were identified: a father with two children (aged 10–11 years); and three brothers (aged one-11 years), all with PCR-confirmed knowlesi malaria. Cases of P. knowlesi demonstrated significant seasonal variation, and correlated with rainfall in the preceding three to five months. ConclusionsPlasmodium knowlesi is the most common cause of malaria admissions to Kudat District Hospital. The wide age distribution and presence of family clusters suggest that transmission may be occurring close to or inside people’s homes, in contrast to previous reports from densely forested areas of Sarawak. These findings have significant implications for malaria control. Prospective studies of risk factors, vectors and transmission dynamics of P. knowlesi in Sabah, including potential for human-to-human transmission, are needed

Flood waves from a controlled breached dam

Students supported: 1 Ph.D Student, 2 MS StudentsA conceptual method to alleviate flood damages due to overtopping failures of small earthfill dams is the incorporation of a relatively thin erosion retarding layer within the dam. This paper investigates the reduction in the reservoir release due to the hypothetical erosion retarding layer. In addition, the paper provides a method for the determination of an optimal location of the layer so as to minimize the maximum possible reservoir release due to a gradually breached earth dam. The transient reservoir flow is simulated by a numerical model, based upon the solution of the one-dimensional St. Venant unsteady open-channel flow equations. These equations are solved by the method of characteristics, with appropriate boundary conditions incorporated into the solution procedure. The numerical simulation model is used to determine the reduction in reservoir release due to a single retarding layer and its optimal location for a wide range of pertinent geometric, hydraulic and dynamic parameters. The sensitivity of the results to variations in the above parameters is discussed.Project # A-035-MO Agreement # 14-31-0001-322

Admixture in Humans of Two Divergent Plasmodium knowlesi Populations Associated with Different Macaque Host Species.

Human malaria parasite species were originally acquired from other primate hosts and subsequently became endemic, then spread throughout large parts of the world. A major zoonosis is now occurring with Plasmodium knowlesi from macaques in Southeast Asia, with a recent acceleration in numbers of reported cases particularly in Malaysia. To investigate the parasite population genetics, we developed sensitive and species-specific microsatellite genotyping protocols and applied these to analysis of samples from 10 sites covering a range of >1,600 km within which most cases have occurred. Genotypic analyses of 599 P. knowlesi infections (552 in humans and 47 in wild macaques) at 10 highly polymorphic loci provide radical new insights on the emergence. Parasites from sympatric long-tailed macaques (Macaca fascicularis) and pig-tailed macaques (M. nemestrina) were very highly differentiated (FST = 0.22, and K-means clustering confirmed two host-associated subpopulations). Approximately two thirds of human P. knowlesi infections were of the long-tailed macaque type (Cluster 1), and one third were of the pig-tailed-macaque type (Cluster 2), with relative proportions varying across the different sites. Among the samples from humans, there was significant indication of genetic isolation by geographical distance overall and within Cluster 1 alone. Across the different sites, the level of multi-locus linkage disequilibrium correlated with the degree of local admixture of the two different clusters. The widespread occurrence of both types of P. knowlesi in humans enhances the potential for parasite adaptation in this zoonotic system

Effects of Late Gestation Episodic heat Stress in the Northeastern United States on Holstein Dams and their Calves

Heat stress negatively impacts dry dairy cows in subtropical climates, but impacts in moderate climates are unknown. The objective of this thesis was to determine if dry cows and their calves in Northern NY and VT are impacted by episodic heat stress and varying levels of heat exposure. Another aim of this study was to determine farmers\u27 knowledge of heat stress, heat abatement use, and the need for future research.Chapter 2 describes a study conducted on a Northern NY farm, where dry cows were housed in moderate heat abatement, meaning fans over a bedded pack or free stalls. Surprisingly, cows had higher reticular temperature and rumination time on hot days. Although not reflected in body temperature or rumination data, these cows were heat-stressed as they stood longer on hot days to dissipate heat. Cows who experienced high amounts of heat stress during the dry period (DP) had a shorter gestation length. Cows who experienced low amounts of heat stress during the DP tended to have higher-quality colostrum than those with moderate heat stress. Cows who experienced high amounts of heat stress during the late DP had lower 21-day milk production. Calves were not statistically affected by in-utero episodic heat stress for the measured variables. Chapter 3 describes a study conducted on a Northern VT farm, where dry cows were housed on pasture for their early DP and on a bedded pack with access to an outdoor sandlot for their late DP. Similar to the study conducted in Chapter 2, this study indicated that cows ruminated longer on hot days. Unlike in Chapter 2, cows only had higher reticular temperature on hot days when housed on pasture, not when they had the option of shade access of the barn. Cows who experienced high amounts of heat stress during the late dry period tended to have greater weight loss from dry off to calving. Eight farmers with varying farm sizes and heat abatement use were interviewed regarding their opinions of heat stress and usage of heat abatement, as described in Chapter 4. Overall, all farmers felt their cows were negatively impacted by heat stress, and most had implemented heat abatement strategies on their farms. A prevalent theme of many interviews was farmers’ hesitancy to install sprinklers as a form of heat abatement due to concerns about animal health and water availability. These studies indicate that dry cows are negatively impacted by episodic heat stress in the Northeast, so heat abatement should be provided during the DP. Farmers in the area believe heat stress negatively affects their cattle and have observed positive impacts of providing heat abatement for their animals

Open-channel Profiles By Newton\u27s Iteration Technique

Computation of surface profiles for steady gradually varied flow can be accomplished by use of Newton\u27s Iteration Technique. The magnitude of error is controlled and the profile depth can be conveniently calculated at selected distances upstream or downstream from a control point. A Fortran IV program is provided for utilizing the technique in a trapezoidal channel. © 1971

Creating an enabling environment for investment in climate services: The case of Uruguay’s National Agricultural Information System

Increasingly challenged by climate variability and change, many of the world’s governments have turned to climate services as a means to improve decision making and mitigate climate-related risk. While there have been some efforts to evaluate the economic impact of climate services, little is known about the contexts in which investments in climate services have taken place. An understanding of the factors that enable climate service investment is important for the development of climate services at local, national and international levels. This paper addresses this gap by investigating the context in which Uruguay’s Ministry of Livestock, Agriculture and Fisheries invested in and developed its National System of Agriculture Information (SNIA), a national-level climate service for the agriculture sector. Using qualitative research methods, the paper uses key documents and 43 interviews to identify six factors that have shaped the decision to invest in the SNIA: (1) Uruguay’s focus on sustainable agricultural intensification; (2) previous work on climate change adaptation; (3) the modernization of the meteorological service; (4) the country’s open data policy; (5) the government’s decision to focus the SNIA on near-term (e.g., seasonal) rather than long-term climate risk; and (6) the participation of key individuals. While the context in which these enablers emerged is unique to Uruguay, it is likely that some factors are generalizable to other countries. Social science research needed to confirm the wider applicability of innovation systems, groundwork, data access and champion is discussed

Molecular detection of human Plasmodium species in Sabah using PlasmoNex™ multiplex PCR and hydrolysis probes real-time PCR

BACKGROUND: Malaria is a vector borne-parasitic disease transmitted through the bite of the infective female Anopheles mosquitoes. Five Plasmodium species have been recognized by World Health Organization (WHO) as the causative agents of human malaria. Generally, microscopic examination is the gold standard for routine malaria diagnosis. However, molecular PCR assays in many cases have shown improvement on the sensitivity and specificity over microscopic or other immunochromatographic assays. METHODS: The present study attempts to screen 207 suspected malaria samples from patients seeking treatment in clinics around Sabah state, Malaysia, using two panels of multiplex PCRs, conventional PCR system (PlasmoNex™) and real-time PCR based on hydrolysis probe technology. Discordance results between two PCR assays were further confirmed by sequencing using 18S ssu rRNA species-specific primers. RESULTS: Of the 207 malaria samples, Plasmodium knowlesi (73.4% vs 72.0%) was the most prevalent species based on two PCR assays, followed by Plasmodium falciparum (15.9% vs 17.9%), and Plasmodium vivax (9.7% vs 7.7%), respectively. Neither Plasmodium malariae nor Plasmodium ovale was detected in this study. Nine discrepant species identification based on both the PCR assays were further confirmed through DNA sequencing. Species-specific real-time PCR only accurately diagnosed 198 of 207 (95.7%) malaria samples up to species level in contrast to PlasmoNex™ assay which had 100% sensitivity and specificity based on sequencing results. CONCLUSIONS: Multiplex PCR accelerate the speed in the diagnosis of malaria. The PlasmoNex™ PCR assay seems to be more accurate than real-time PCR in the speciation of all five human malaria parasites. The present study also showed a significant increase of the potential fatal P. knowlesi infection in Sabah state as revealed by molecular PCR assays