The Ever-Shifting Internet Population

Presents findings from surveys conducted between March and May 2002. Takes a new look at Internet access and the digital divide. Explores factors of cost, lack of technology skills, and physical access (particularly for persons with disabilities)

Systems of Winter Milk Production based on all Autumn Calving Cows

End of Project ReportA supply of winter milk is needed by certain milk processors for the production of high value dairy products with a short shelf life to balance the high level of commodity based products which are mainly manufactured from seasonal milk produced from spring calving herds. Winter milk is generally produced by suppliers with split calving herds. A proportion of the cows (30-50%) calve in Autumn (September-December) to supply winter milk for which they receive a winter bonus for a contracted supply for the months of October to February. The remainder of the herd calve in Spring (Feb-April) and produce milk mainly off grass for which no bonus is paid. This system evens out the supply of milk throughout the year but complicates management, as it involves running two herds on the farm, with two calving seasons, two breeding seasons and two sets of replacement heifers to be reared. Also there is no break from milking. A system of winter milk production based on calving all of the cows in Autumn would be simpler, as it would involve only one herd, with a break from milking in late Summer and would appeal to many winter milk producers. In this study the feasibility of operating an all Autumn calving herd was examined, in terms of management, calving, winter feeding, reproduction and summer grazing. The herd was located in the Ballyderown farm attached to the Moorepark Research Centre. Alternative winter feeding systems were put in place over a three year period to compare the feed requirements and milk production of each system. A control system based on grass silage as the sole forage was compared with one where grass silage was supplemented with extended grazing of grass in late Autumn and early Spring or with a system based on a mixed forage diet based on grass silage, maize silage, brewers grains or a brewers grains/beet pulp mix. Grass silage and maize silage was produced within each system and the cows on each system were grazed separately within their own farmlets. The overall stocking rate for each system was 2.7 cows/ha using 350 kg N fertiliser/ha in addition to cattle slurry. Cows were dried off in mid-late July and were grazed tightly until calving down. The calving season extended from early September to early December. Most cows calved down outdoors at pasture or in a calving paddock without assistance. Cows were housed from early November to late March and were allocated to their respective diets in batches according to milk yield, lactation number and calving date. The cows given access to winter grass were given a daily allocation of grass (6-8 kg DM/cow) and grazed between morning and evening milking

Factors influencing the efficiency of a marker-assisted introgression programme in Merino sheep

This study investigated a marker-assisted introgression programme in Australian Merino sheep. The goal was to introgress an allele with a large negative effect on fibre diameter into a Merino flock possessing medium average fibre diameter. The influence of two factors was explored: the strategy used to select animals from the purebred and backcross line for backcrossing purposes and the use of selection on background markers to accelerate the return to the purebred line's genome. The results were compared to introgression based on EBVs only. Introgression using EBVs only produced almost the same response in the dollar index as marker-based introgression methods. However, this study did not account for some of the costs associated with implementing the programmes, including the costs of phenotyping and genotyping. Given that the cost of measuring fibre diameter is low, it was concluded that introgression on EBVs only would be the preferred method since the marginal profit of marker-assisted introgression would not be large enough to cover the additional cost of genotyping. In marker-assisted introgression, reciprocal crossing of male and female selection candidates from the backcross and the purebred line was the most advantageous strategy from a practical and profit point of view. Selection for background markers was less profitable in this study than recovering the donor genome by selection on phenotype

Investigation of pellet-clad interaction during load-follow operation in a pressurized water reactor using VERA-CS

This thesis is a comprehensive study on the effect load-follow operation has on fuel failure risk in a PWR. PWR1, a commercial reactor that performed load-follow power maneuvers in cycle 21, was modeled using VERA-CS. The effects of a jump-in approach, starting depletion in cycle 17 as compared to cycle 1, were shown to be negligible after two cycles of depletion. Both low power physics tests and critical boron comparisons show excellent agreement between the VERA-CS predictions and the plant-measured data after cycle 19. In addition to cycle depletion, five load-follow power maneuvers in the first 24 days of cycle 21 were simulated using hourly depletion steps. Predictions showed an overestimation of the axial offset behavior during the load-follow operation but the overall reactivity of the core was in good agreement. The linear heat rate and coolant temperature calculated by VERA-CS were used as boundary conditions for BISON fuel performance calculations. Using the maximum hoop stress as the indicator of fuel failure risk, the different load-follow power maneuvers were compared to the initial start-up ramp. The maximum clad hoop stress occurred during the start-up ramp and was estimated to be 94 MPa, the subsequent maneuvers showed similar magnitudes regardless of the change in power. No correlation was observed between the characteristics of the load-follow power maneuver and the resulting maximum clad hoop stress. Neither the magnitude of the decrease in power, hold period, nor intermediate power steps showed a variation in the maximum clad hoop stress observed after a return to full power this early in the cycle. To reduce the number of fuel performance calculations required to determine the safety of a power maneuver, a screening process was developed based on a weighted change in conditioned power. By selecting the top 1000 fuel rods showing a positive weighted change in linear heat rate, the limiting fuel pin for the maneuver is included, with most of the selected pins showing elevated hoop stresses

A comparison of 4 predictive models of calving assistance and difficulty in dairy heifers and cows

peer-reviewedThe aim of this study was to build and compare predictive models of calving difficulty in dairy heifers and cows for the purpose of decision support and simulation modeling. Models to predict 3 levels of calving difficulty (unassisted, slight assistance, and considerable or veterinary assistance) were created using 4 machine learning techniques: multinomial regression, decision trees, random forests, and neural networks. The data used were sourced from 2,076 calving records in 10 Irish dairy herds. In total, 19.9 and 5.9% of calving events required slight assistance and considerable or veterinary assistance, respectively. Variables related to parity, genetics, BCS, breed, previous calving, and reproductive events and the calf were included in the analysis. Based on a stepwise regression modeling process, the variables included in the models were the dam's direct and maternal calving difficulty predicted transmitting abilities (PTA), BCS at calving, parity; calving assistance or difficulty at the previous calving; proportion of Holstein breed; sire breed; sire direct calving difficulty PTA; twinning; and 2-way interactions between calving BCS and previous calving difficulty and the direct calving difficulty PTA of dam and sire. The models were built using bootstrapping procedures on 70% of the data set. The held-back 30% of the data was used to evaluate the predictive performance of the models in terms of discrimination and calibration. The decision tree and random forest models omitted the effect of twinning and included only subsets of sire breeds. Only multinomial regression and neural networks explicitly included the modeled interactions. Calving BCS, calving difficulty PTA, and previous calving assistance ranked as highly important variables for all 4 models. The area under the receiver operating characteristic curve (ranging from 0.64 to 0.79) indicates that all of the models had good overall discriminatory power. The neural network and multinomial regression models performed best, correctly classifying 75% of calving cases and showing superior calibration, with an average error in predicted probability of 3.7 and 4.5%, respectively. The neural network and multinomial regression models developed are both suitable for use in decision-support and simulation modeling

Thermal stability of exchange bias systems based on MnN

At the present time there is a requirement to identify new antiferromagnetic alloys or compounds which might be suitable for the production of exchange bias systems. The phenomenon of exchange bias remains crucial for the operation of all read heads in hard disk drives and also has potential for use in magnetic random access memory (MRAM) systems. There is also an increasing interest in the use of antiferromagnets themselves in spintronic devices. Generally for applications the alloy IrMn is used, however given that Iridium is one of the rarest, and therefore most expensive elements on Earth, there is a search for alternative materials. In this paper we report on a study of the compound MnN in terms of its thermal stability. We have produced polycrystalline films of this compound with sub 10 nm grains and examined the thermal stability in layers of thicknesses of up to 30 nm. Using thermal activation studies we have determined a room temperature value of the anisotropy constant of this compound in a tetragonal structure of up to (6.3 ± 0.3) × 10 6 erg/cm 3 . The antiferromagnetic grains can be aligned by thermal annealing at an optimum temperature of 380 K. Above this temperature the magnetic properties deteriorate possibly due to nitrogen desorption

Med news

The Med News was a newsletter published from 1960-1962 by the Student American Medical Association (SAMA) at Boston University School of Medicine

Early intervention for relapse in schizophrenia: results of a 12-month randomized controlled trial of cognitive behavioural therapy

Background. The paper describes a randomized controlled trial of targeting cognitive behavioural therapy (CBT) during prodromal or early signs of relapse in schizophrenia. We hypothesized that CBT would result in reduced admission and relapse, reduced positive and negative symptoms, and improved social functioning. Method. A total of 144 participants with schizophrenia or a related disorder were randomized to receive either treatment as usual (TAU) (N=72) or CBT+TAU (N=72). Participants were prospectively followed up between entry and 12 months. Results. At 12 months, 11 (15.3%) participants in the CBT group were admitted to hospital compared to 19 (26.4%) of the TAU group (hazard ratio=0.53, P=0.10, 95% CI 0.25, 1.10). A total of 13 (18.1%) participants in CBT relapsed compared to 25 (34.7%) in TAU (hazard ratio=0.47,