Solving the Uncapacitated Single Allocation p-Hub Median Problem on GPU

A parallel genetic algorithm (GA) implemented on GPU clusters is proposed to solve the Uncapacitated Single Allocation p-Hub Median problem. The GA uses binary and integer encoding and genetic operators adapted to this problem. Our GA is improved by generated initial solution with hubs located at middle nodes. The obtained experimental results are compared with the best known solutions on all benchmarks on instances up to 1000 nodes. Furthermore, we solve our own randomly generated instances up to 6000 nodes. Our approach outperforms most well-known heuristics in terms of solution quality and time execution and it allows hitherto unsolved problems to be solved

Lightning strike simulation in composite structures

Lighting strike is one of the critical threats to the safety of composite aircrafts during flight. This work reports on numerical simulation of lightning strike in composite structures. Different modelling techniques using the commercial software ABAQUS, together with damage models are studied to find the most appropriate one in comparison to experimental results. Once the numerical model is validated, the effect of insertion of carbon nanotubes (CNTs) and metallic mesh in the composite is investigated. It is concluded that inserting CNTs in the top layer of the composite can improve its lightning strike protection noticeably

Angiogenesis-dependent and independent phases of intimal hyperplasia.

BACKGROUND: Neointimal vascular smooth muscle cell (VSMC) proliferation is a primary cause of occlusive vascular disease, including atherosclerosis, restenosis after percutaneous interventions, and bypass graft stenosis. Angiogenesis is implicated in the progression of early atheromatous lesions in animal models, but its role in neointimal VSMC proliferation is undefined. Because percutaneous coronary interventions result in induction of periadventitial angiogenesis, we analyzed the role of this process in neointima formation. METHODS AND RESULTS: Local injury to the arterial wall in 2 different animal models induced periadventitial angiogenesis and neointima formation. Application of angiogenesis stimulators vascular endothelial growth factor (VEGF-A165) or a proline/arginine-rich peptide (PR39) to the adventitia of the injured artery induced a marked increase in neointimal thickening beyond that seen with injury alone in both in vivo models. Inhibition of either VEGF (with soluble VEGF receptor 1 [sFlt1]) or fibroblast growth factor (FGF) (with a dominant=negative form of FGF receptor 1 [FGF-R1DN]), respectively, signaling reduced adventitial thickening induced by VEGF and PR39 to the level seen with mechanical arterial injury alone. However, neither inhibitor was effective in preventing neointimal thickening after mechanical injury when administered in the absence of angiogenic growth factor. CONCLUSIONS: Our findings indicate that adventitial angiogenesis stimulates intimal thickening but does not initiate it

The value of supplementary feeding to pre-weaned and weaned lambs grazing Italian ryegrass

The variation in, and often the disappointingly poor weight gains and the inability of lambs to achieve desirable carcass grades on ryegrass pastures have long been a concern to researchers, extension officers, advisors and farmers. The objectives of this study were to investigate whether concentrate supplementation to lambs on Italian ryegrass (Lolium multiflorum cv Midmar) pastures would improve the performance of lambs, and what the optimum level of supplementation is to lambs on the pasture. The investigation extended over the pre- and post-weaning growth phases of lambs and was conducted during two consecutive seasons at the Cedara Research Station in the KwaZulu-Natal Mistbelt. The pre-weaning stocking rate applied, was 20 South African Mutton Merino ewes with lambs/ha and the following treatments were applied: Control: continuous grazing - no creep feed; forward creep grazing by the lambs in a rotational grazing system where the lambs were allowed to graze paddocks allocated to the ewes, plus the next paddock in their series of grazing paddocks; 100 g creep feed/lamb/day; 250 g creep feed/lamb/day and creep feed ad libitum. The post-weaning stocking rate applied, was 50 lambs/ha and treatments were: Control - no supplement; 250 g of supplement/lamb/day (only the second season); 500 g of supplement/lamb/day and supplement ad libitum. From 42 days of age to weaning, supplementation significantly improved the live weight gain of suckling lambs. Creep feed intake varied between 300 and 350 g/lamb/day. The average daily gain of the weaned lambs improved significantly with supplementation. No significant advantage in terms of growth was gained by supplementing the weaned lambs at levels of higher than 500 g/day. South African Journal of Animal Science Vol.32(1) 2002: 30-3

Finiteness and orbifold Vertex Operator Algebras

In this paper, I investigate the ascending chain condition of right ideals in the case of vertex operator algebras satisfying a finiteness and/or a simplicity condition. Possible applications to the study of finiteness of orbifold VOAs is discussed.Comment: 12 pages, comments are welcom

Lead isotopes in deep-sea coral skeletons: ground-truthing and a first deglacial Southern Ocean record

Past changes in seawater lead (Pb) isotopes record the temporal evolution of anthropogenic pollution, continental weathering inp uts, and ocean current transport. To advance our ability to reconstruct this signature, we present methodological developments that allow us to make precise and accurate Pb isoto pe measurements on deep-sea coral aragonite, and apply our approach to generate the f irst Pb isotope record for the glacial to deglacial mid-depth Southern Ocean. Our refined methodology includes a two-step anion e xchange chemistry procedure and measurement using a 207 Pb- 204 Pb double spike on a ThermoFinnigan Triton TIMS instrument. By employing a 10 12 Ω resistor (in place of a 10 Ω resistor) to measure the low- abundance 204 Pb ion beam, we improve the internal precision on 206,207,208 Pb/ 204 Pb for a 2 ng load of NIST-SRM-981 Pb from typically ~420 ppm to ~260 ppm (2 s.e.), and the long term external reproducibility from ~960 ppm to ~580 ppm (2 s.d.). Furthermore, for a typical 500 mg coral sample with low Pb concentrations (~6-10 p pb yielding ~3-5 ng Pb for analysis), we obtain a comparable internal precision of ~150-250 ppm for 206,207,208 Pb/ 204 Pb, indicating a good sensitivity for tracing natural Pb sources to the oceans. Successful extraction of a seawater signal from deep-sea coral aragonite furth er relies on careful physical and chemical cleaning steps, which are necessary to remove anthr opogenic Pb contaminants and obtain results that are consistent with ferromanganese cru sts. Applying our approach to a collection of late glaci al and deglacial corals (~12-40 ka BP) from south of Tasmania at ~1.4-1.7 km water dep th, we generated the first intermediate water Pb isotope record from the Southern Ocean. Th at record reveals millennial timescale variability, controlled by binary mixing between tw o Pb sources, but no distinct glacial- interglacial Pb isotope shift. Mixing between natur al endmembers is fully consistent with our data and points to a persistence of the same Pb sou rces through time, although we cannot rule out a minor influence from recent anthropogenic Pb. Whereas neodymium (Nd) isotopes in the Southern Ocean respond to global ocean circulat ion changes between glacial and interglacial periods, Pb isotopes record more local ised mixing within the Antarctic Circumpolar Current, potentially further modulated by climate through changing terrestrial inputs from southern Africa or Australia. Such deco upling between Pb and Nd isotopes in the Southern Ocean highlights their potential to provid e complementary insights into past oceanographic variability

The metabolic syndrome in black hypertensive women waist circumference more strongly related than body Mass index

Objective. To examine the association between measures of obesity and features of the metabolic  syndrome in treated black female hypertensive subjects.Design. Cross-sectional study.Setting. An urban primary health care centre in Mamelodi, Pretoria.Subjects. Women with hypertension and without known diabetes mellitus or secondary causes of  hypertension. In total124 women participated, with a mean age of 56.9 years (standard deviation (SO) 11.0) and mean body mass index (BMI) of 34.1 kg/m' (SO 8.1).Main outcome measures. Blood pressure, glucose, insulin and lipid levels.Results. Waist circumference and waist-hip ratio were more strongly associated with insulin, uric acid,  glucose and triglycerides than was BMI. Statistically significant associations were found between waist circumference and low high-density lipoprotein HOL cholesterol (standardised regression coefficient --0.006, standard error of the mean (SEM) 0.002), log triglycerides (0.007, SEM 0.003), uric acid (0.002, SEM 0.001) and log insulin (0.012, SEM 0.003). BMI was only significantly associated with uric acid  (0.002, SEM 0.002) and log insulin (0.009, SEM 0.004).Conclusion. In a group of black hypertensive women measures of central obesity were more strongly  associated with components of the metabolic syndrome than BMI

Quantum Storage of Photonic Entanglement in a Crystal

Entanglement is the fundamental characteristic of quantum physics. Large experimental efforts are devoted to harness entanglement between various physical systems. In particular, entanglement between light and material systems is interesting due to their prospective roles as "flying" and stationary qubits in future quantum information technologies, such as quantum repeaters and quantum networks. Here we report the first demonstration of entanglement between a photon at telecommunication wavelength and a single collective atomic excitation stored in a crystal. One photon from an energy-time entangled pair is mapped onto a crystal and then released into a well-defined spatial mode after a predetermined storage time. The other photon is at telecommunication wavelength and is sent directly through a 50 m fiber link to an analyzer. Successful transfer of entanglement to the crystal and back is proven by a violation of the Clauser-Horne-Shimony-Holt (CHSH) inequality by almost three standard deviations (S=2.64+/-0.23). These results represent an important step towards quantum communication technologies based on solid-state devices. In particular, our resources pave the way for building efficient multiplexed quantum repeaters for long-distance quantum networks.Comment: 5 pages, 3 figures + supplementary information; fixed typo in ref. [36