BACE1 Polymorphisms Do Not Influence Platelet Membrane β-secretase Activity or Genetic Susceptibility for Alzheimer’s Disease in the Northern Irish Population

ß-Site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a biological and positional candidate gene for Alzheimer’s disease (AD). BACE1 is a protease that catalyses APP cleavage at the ß-secretase site. We evaluated all common and putatively functional polymorphisms in the genomic region encompassing BACE1 for an association with AD, and for functional effects on platelet ß-secretase activity. Tag SNPs (n = 10) derived from phase II of the International HapMap Project, and a nonsynonymous variant, were successfully genotyped in 901 Caucasian individuals from Northern Ireland using Sequenom iPLEX and TaqMan technologies. APOE genotyping was performed by PCR-RFLP. Platelet membrane ß-secretase activity was assayed in a subset of individuals (n = 311). Hardy–Weinberg equilibrium was observed for all variants. Evidence for an association with AD was observed with multi-marker haplotype analyses (P = 0.01), and with rs676134 when stratified for APOE genotype (P = 0.02), however adjusting for multiple testing negated the evidence for association of this variant with AD. ?2 analysis of genotype and allele frequencies in cases versus controls for individual SNPs revealed no evidence for association (5% level). No genetic factors were observed that significantly influenced platelet membrane ß-secretase activity. We have selected an appropriate subset of variants suitable for comprehensive genetic investigation of the BACE1 gene. Our results suggest that common BACE1 polymorphisms and putatively functional variants have no significant influence on genetic susceptibility to AD, or platelet ß-secretase activity, in this Caucasian Northern Irish population.

Shared or unshared parental care in overwintering brent geese (Branta bernicla hrota)

We examine brood size effects on the behaviour of wintering parent and juvenile brent geese (Branta bernicla hrota) to test predictions of shared and unshared parental care models. The behaviour of both parents and offspring appear to be influenced by declining food availability over the winter. Parental vigilance increased with brood size and may be explained by vigilance having functions in addition to antipredator behaviour where the benefits are shared among the brood. There was no increase in parental aggression with brood size and this does not fit the prediction of shared care. Nevertheless, large families are able to monopolize better feeding areas compared with smaller families and large families static feed more but walk feed less than do small families, the former apparently being the preferred mode. The presence of additional young, rather than increasing the amount of parental aggression, seems to enhance the family's competitive ability. Because parents with large broods benefit from enhanced access to resources there is likely to be no additional significant cost in the parental care of larger broods (sensu Trivers 1972).

Factors influencing the distribution of native and introduced Gammarus spp. in Irish river systems

Populations of Gammarus duebeni celticus, previously the only amphipod species resident in the rivers of the Lough Neagh catchment, N. Ireland, have been subjected to invasion by G. pulex from the British mainland. Numerous previous studies have investigated the potential behavioural mechanisms, principally differential mutual predation, underlying the replacement of G. d. celticus by G. pulex in Irish waters, and the mutually exclusive distributions of these species in Britain and mainland Europe. However, the relative degree of influence of abiotic versus biotic factors in structuring these amphipod communities remains unresolved. This study used principal component analysis (PCA) to distinguish physico-chemical parameters that have significant roles in determining the current distribution of G. pulex relative to G. d. celticus in L. Neagh rivers. We show that the original domination of rivers by the native G. d, celticus has changed radically, with many sites in several rivers containing either both species or only G. pulex. G. pulex was more abundant than the G. d. celticus in sites with low dissolved oxygen levels. This was reflected in the macroinvertebrate assemblages associated with G. pulex in these sites, which tended to be those tolerant of low biological water quality. The present study thus emphasizes the importance of the habitat template, particularly water quality, for Gammarus spp. interactions. If rivers become increasingly stressed by organic pollution, it is probable the range expansion of G. pulex will continue. Because these two species are not ecological equivalents, the outcomes of G. pulex incursions into G. d. celticus sites may ultimately depend on the prevailing physico-chemical regimes in each site.

Liquid structure of the ionic liquid, 1-methyl-4-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide determined from neutron scattering and molecular dynamics simulations

The liquid structure of 1-methyl-4-cyanopyridinium bis {(trifluoromethyl)sulfonyl}imide, a prototypical ionic liquid containing an electron-withdrawing group on the cation, has been investigated at 368 K. Experimental neutron scattering combined with empirical potential structure refinement analysis of the data and classical molecular dynamics simulations have been used to probe the liquid structure in detail. Both techniques generated highly consistent results that provide valuable validation of the force fields and refinement approaches. A significant degree of apparent charge ordering is found in the liquid structure, although the nonspherical shape of the ions results in interpenetration of cations into the first shell of adjacent cations, with much shorter closest contact distances than the averaged center-of-mass cation-cation and cation-anion separations.

A highly efficient synthetic procedure for deuteriating imidazoles and imidazolium salts

Both substituted imidazoles and 1,3-dialkylimidazolium salts can be fully deuteriated on the heterocyclic ring using D2O over heterogeneous Pd catalysts: deuteriated 1-alkyl-3-methylimidazolium chloride and hexafluorophosphate ionic liquids can also be prepared in good yields utilising readily available and relatively low cost sources of deuterium.

Roche tomography of cataclysmic variables - III. Star-spots on AE Aqr

We present a Roche tomography reconstruction of the secondary star in the cataclysmic variable AE Aqr. The tomogram reveals several surface inhomogeneities that are due to the presence of large, cool star-spots. In addition to a number of lower latitude spots, the maps also show the presence of a large, high-latitude spot similar to that seen in Doppler images of rapidly rotating isolated stars, and a relative paucity of spots at a latitude of 40 degrees. In total, we estimate that some 18 per cent of the Northern hemisphere of AE Aqr is spotted.

Software project initiation and planning – an empirical study

This study describes a study of 14 software companies, on how they initiate and pre-plan software projects. The aim was to obtain an indication of the range of planning activities carried out. The study, using a convenience sample, was carried out using structured interviews, with questions about early software project planning activities. The study offers evidence that an iterative and incremental development process presents extra difficulties in the case of fixed-contract projects. The authors also found evidence that feasibility studies were common, but generally informal in nature. Documentation of the planning process, especially for project scoping, was variable. For incremental and iterative development projects, an upfront decision on software architecture was shown to be preferred over allowing the architecture to just ‘emerge’. There is also evidence that risk management is recognised but often performed incompletely. Finally appropriate future research arising from the study is described.

Evaluation of Gas Solubility Prediction in Ionic Liquids using COSMOthermX

As the range of available ionic liquids increases, methods by which important engineering parameters such as gas solubilities can be estimated from simple structural information become ever more desirable. COSMO-based thermodynamic models, such as that used by COSMOthermX, allow the determination of such data for pure and mixed component systems. Herein, we evaluate the predictive capability of COSMOthermX through a comparison with literature data obtained from the IUPAC database which contains data for 15 gases in 27 ionic liquids, To determine any effect inherent to ionic liquids, gas solubility predictions were first performed for selected molecular solvents at constant temperature and pressure. Further estimations of gas solubility at temperatures ranging from (278 to 368) K at 0.1 MPa in water were performed for 14 gases. The Study has demonstrated that COSMOthermX is capable of predicting, qualitatively, gas solubilities in ionic liquids and, hence, reducing the amount of unnecessary experimental measurements prior to specific applications using ionic liquids.

Spectrally efficient cooperative diversity protocol for uplink wireless transmission

A spectrally efficient cooperative protocol for uplink wireless transmission in a centralised communication system is proposed, where each of the N users play the relaying and source roles simultaneously by using superposition (SP) modulation. The probability density function of the mutual information between SP-modulated transmitted and received signals of the cooperative uplink channels is derived. Using the high-signal-to-noise ratio (SNR) approximation of this density function, the outage probability formula of the system as well as its easily computable tight upper and lower bounds are obtained and these formulas are evaluated numerically. Numerical results show that the proposed strategy can achieve around 3 dB performance gain over comparable schemes. Furthermore, the multiplexing and diversity tradeoff formula is derived to illustrate the optimal performance of the proposed protocol, which also confirms that the SP relaying transmission does not cause any loss of data rate. Moreover, performance characterisation in terms of ergodic and outage capacities are studied and numerical results show that the proposed scheme can achieve significantly larger outage capacity than direct transmission, which is similar to other cooperative schemes. The superiority of the proposed strategy is demonstrated by the fact that it can maintain almost the same ergodic capacity as the direct transmission, whereas the ergodic capacity of other cooperative schemes would be much worse.

Cooperative transmission protocol with full diversity and iterative detection

The authors propose a three-node full diversity cooperative protocol, which allows the retransmission of all symbols. By allowing multiple nodes to transmit simultaneously, relaying transmission only consumes limited bandwidth resource. To facilitate the performance analysis of the proposed cooperative protocol, the lower and upper bounds of the outage probability are first developed, and then the high signal-to-noise ratio behaviour is studied. Our analytical results show that the proposed strategy can achieve full diversity. To achieve the performance gain promised by the cooperative diversity, at the relays decode-and-forward strategy is adopted and an iterative soft-interference-cancellation minimum mean-squared error equaliser is developed. The simulation results compare the bit-error-rate performance of the proposed protocol with the non-cooperative scheme and the scheme presented by Azarian et al. ( 2005).