A note on the evaluation of a beta-casein variant in bovine breeds by allele-specific PCR and relevance to β-casomorphin

peer-reviewedThis work was supported by Enterprise Ireland and by a Teagasc Walsh fellowship to A.F. Keating.Two genetic variants of the bovine β-casein gene (A1 and B) encode a histidine residue at codon 67, resulting in potential liberation of a bioactive peptide, β-casomorphin, upon digestion. An allele-specific PCR (AS-PCR) was evaluated to distinguish between the β-casomorphin-releasing variants (A1 and B) and the non-releasing variants. AS-PCR successfully distinguished β-casein variants in 41 of 42 animals as confirmed by sequence analysis. Overall, while the incidence of the homozygous A1 and B animals (i.e., homozygous for the histidine residue; 21.4%) was lower than that for animals without the histidine residue (30.9% respectively), 69% of animals carried at least one allele for the histidine residue at codon 67.Teagasc Walsh Fellowship ProgrammeEnterprise Irelan

Radix-2n serial–serial multipliers

All serial–serial multiplication structures previously reported in the literature have been confined to bit serial–serial multipliers. An architecture for digit serial–serial multipliers is presented. A set of designs are derived from the radix-2n design procedure, which was first reported by the authors for the design of bit level pipelined digit serial–parallel structures. One significant aspect of the new designs is that they can be pipelined to the bit level and give the designer the flexibility to obtain the best trade-off between throughput rate and hardware cost by varying the digit size and the number of pipelining levels. Also, an area-efficient digit serial–serial multiplier is proposed which provides a 50% reduction in hardware without degrading the speed performance. This is achieved by exploiting the fact that some cells are idle for most of the multiplication operation. In the new design, the computations of these cells are remapped to other cells, which make them redundant. The new designs have been implemented on the S40BG256 device from the SPARTAN family to prove functionality and assess performance

Pressure dependence of the superconducting transition temperature in C6_6Yb and C6_6Ca

We have studied the evolution, with hydrostatic pressure, of the recently discovered superconductivity in the graphite intercalation compounds C$_6$Yb and C$_6$Ca. We present pressure-temperature phase diagrams, for both superconductors, established by electrical transport and magnetization measurements. In the range 0-1.2 GPa the superconducting transition temperature increases linearly with pressure in both materials with $dT_c/dP = +0.39 K/GPa$ and $dT_c/dP = +0.50 K/GPa$ for C$_6$Yb and C$_6$Ca respectively. The transition temperature in C$_6$Yb, which has beenmeasured up to 2.3 GPa, reaches a peak at around 1.8 GPa and then starts to drop. We also discuss how this pressure dependence may be explained within a plasmon pairing mechanism.Comment: 4 pages, 3 figure

Clustering-Based Materialized View Selection in Data Warehouses

Materialized view selection is a non-trivial task. Hence, its complexity must be reduced. A judicious choice of views must be cost-driven and influenced by the workload experienced by the system. In this paper, we propose a framework for materialized view selection that exploits a data mining technique (clustering), in order to determine clusters of similar queries. We also propose a view merging algorithm that builds a set of candidate views, as well as a greedy process for selecting a set of views to materialize. This selection is based on cost models that evaluate the cost of accessing data using views and the cost of storing these views. To validate our strategy, we executed a workload of decision-support queries on a test data warehouse, with and without using our strategy. Our experimental results demonstrate its efficiency, even when storage space is limited

Transition and flow-induced scattering of acoustic modes in ducts

The propagation of unsteady disturbances in ducts of slowly-varying geometry, such as those typical of an aero-engine, can be successfully modelled using a multiple scales approach. The multiple-scales approach has a number of distinct advantages over full numerical methods. Previous authors have validated the accuracy and usefulness of the multiple scales approach by comparing with results obtained using the finite element method, using realistic aero-engine configurations. Cut-on cut-off transition of acoustic modes in hard-walled ducts with irrotational mean flow is well understood. However, previous finite-element simulations of this phenomenon appear to indicate the possibility of energy scattering into neighbouring modes at large Helmholtz numbers. In this thesis, an attempt is made to explain such scattering phenomena in slowly varying aero-engine ducts using multiple-scales techniques. In order to model modal scattering a good understanding of cut-on cut-off transition is necessary. Here, the well known single turning point is revisited, and our understanding of cut-on cut-off transition is extended to include an analysis of a double turning point. Then using a similar apparatus, modal scattering in the case where a mode undergoes cut-on cut-off transition is investigated. It is found that, for sufficiently high frequencies, a mechanism exists whereby a propagating incident mode can be scattered into neighbouring modes provided that a mean flow exists within the duct. An asymptotic analysis of this mechanism is presented and, by solving numerically a composite solution, results in a duct of rectangular cross section are obtained. The energy distribution of the incident and neighbouring scattered modes reveals an interaction and exchange of energy with the mean flow. This work now allows greater insight as well as more accurate and fast computations of high frequency mode propagation in slowly-varying hard walled ducts using multiple-scales approaches

Effects of time resolution on finances and self-consumption when modeling domestic PV-battery systems

When modeling a renewable energy system, the timestep to use is an important consideration. Timestep, or time resolution, can have an impact on results, influencing the sizing of the system and whether or not to invest at all. In this work, real measured data for an entire year at 15-s resolution from a rooftop PV array and 8 household loads in the UK are used. The PV and load time series are averaged to lower resolution: 1-min, 5-min, 30-min and 1-h, and the results from using them as input to a 25-year simulation of PV-only and PV-battery systems are compared to the 15-s resolution results. Load resolution is confirmed to be more important than PV resolution for improving accuracy of self-sufficiency and cost metrics; the presence of a battery is confirmed to reduce the errors of using low resolution compared to PV-only. However, these findings only apply to the commonly tested Greedy algorithm but not the newly developed Emissions Arbitrage algorithm. A wider range of metrics are calculated here than in previous work, finding consistency in that low resolution overstates the benefits of PV-battery, but variation in percentage difference across the metrics used. Further aspects not studied before include: the diminishing returns in computation speed when time resolution is lowered, and the effect of time resolution on the tipping point when certain configurations become more attractive propositions than others. Time resolution of input data and modeling are issues not only for researchers in academia and industry, but from a consumer protection perspective too

Empirical analyses of the length, weight, and condition of adult Atlantic salmon on return to the Scottish coast between 1963 and 2006

Sea age, size, and condition of adult Atlantic salmon (Salmo salar) are prime determinants of individual, and hence population, productivity. To elucidate potential mechanisms, 151 000 records of salmon returning to six Scottish coastal sites over 44 years were analysedfor length, weight, and condition, by site, sex, sea age, and river age. After correcting for capture effort biases, all sites showed seasonal increases in length and weight for both 1 sea winter (1SW) and 2SW fish. However, whereas condition increased slightly with season for 2SW, it decreased notably for 1SW. Sites showed common decadal trends in length, weight, and condition. Within years, length and weight residuals from trends were coherent across sites, but residuals from condition trends were not. Rates of seasonal condition change also showed decadal trends, dramatically different between sea ages, but common across sites within sea-age groups. Longer salmon were disproportionately heavy in all seasons. 1SW condition was markedly lower in 2006. Detrended correlations withoceanic environmental variables were generally not significant, and always weak. A published correlation between the condition of 1SW salmon caught at a single site and sea surface temperatures in the Northeast Atlantic could not be substantiated for any of the six fisheries over the wider time-scales examined

Electron Spin Injection at a Schottky Contact

We investigate theoretically electrical spin injection at a Schottky contact between a spin-polarized electrode and a non-magnetic semiconductor. Current and electron density spin-polarizations are discussed as functions of barrier energy and semiconductor doping density. The effect of a spin-dependent interface resistance that results from a tunneling region at the contact/semiconductor interface is described. The model can serve as a guide for designing spin-injection experiments with regard to the interface properties and device structure.Comment: 4 pages, 4 figure

Self-Organized Criticality in a Fibre-Bundle type model

The dynamics of a fibre-bundle type model with equal load sharing rule is numerically studied. The system, formed by N elements, is driven by a slow increase of the load upon it which is removed in a novel way through internal transfers to the elements broken during avalanches. When an avalanche ends, failed elements are regenerated with strengths taken from a probability distribution. For a large enough N and certain restrictions on the distribution of individual strengths, the system reaches a self-organized critical state where the spectrum of avalanche sizes is a power law with an exponent $\tau\simeq 1.5$.Comment: 10 pages, 6 figures. To be published in Physica

Sampling techniques for and interpretation of milk urea nitrogen concentration

Representative MUN values can be obtained by testing a milk sample before milking, at AM or PM milking, or with an in-line siphon sampling device. MUN values obtained from homogenous milking strings are as accurate as an average MUN value obtained by sampling each cow in the string. Bulk tank sampling is not advisable because of the variation in MUN caused by stage of lactation. Small herds that feed a single TMR should use the average MUN from cows between 60 and 200 days in milk. Monthly sampling is recommended to build a database. The effect of diet changes on MUN can be assessed within 7 days.; Dairy Day, 1998, Kansas State University, Manhattan, KS, 1998