Queen's University Belfast

About: Queen's University Belfast is a education organization based out in Belfast, United Kingdom. It is known for research contribution in the topics: Population & Context (language use). The organization has 25457 authors who have published 55463 publications receiving 1751346 citations. The organization is also known as: Queen's College, Belfast & Queen's College.

Glacial Survival of Boreal Trees in Northern Scandinavia

Abstract: It is commonly believed that trees were absent in Scandinavia during the last glaciation and first recolonized the Scandinavian Peninsula with the retreat of its ice sheet some 9000 years ago. Here, we show the presence of a rare mitochondrial DNA haplotype of spruce that appears unique to Scandinavia and with its highest frequency to the west—an area believed to sustain ice-free refugia during most of the last ice age. We further show the survival of DNA from this haplotype in lake sediments and pollen of Trondelag in central Norway dating back ~10,300 years and chloroplast DNA of pine and spruce in lake sediments adjacent to the ice-free Andoya refugium in northwestern Norway as early as ~22,000 and 17,700 years ago, respectively. Our findings imply that conifer trees survived in ice-free refugia of Scandinavia during the last glaciation, challenging current views on survival and spread of trees as a response to climate changes.

Blood pressure lowering in patients without prior cerebrovascular disease for prevention of cognitive impairment and dementia

Abstract: Background This is an update of a previous review (McGuinness 2006). Hypertension and cognitive impairment are prevalent in older people. Hypertension is a direct risk factor for vascular dementia (VaD) and recent studies have suggested hypertension impacts upon prevalence of Alzheimer's disease (AD). Therefore does treatment of hypertension prevent cognitive decline? Objectives To assess the effects of blood pressure lowering treatments for the prevention of dementia and cognitive decline in patients with hypertension but no history of cerebrovascular disease. Search methods The Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL, LILACS as well as many trials databases and grey literature sources were searched on 13 February 2008 using the terms: hypertens$ OR anti-hypertens$. Selection criteria Randomized, double-blind, placebo controlled trials in which pharmacological or non-pharmacological interventions to lower blood pressure were given for at least six months. Data collection and analysis Two independent reviewers assessed trial quality and extracted data. The following outcomes were assessed: incidence of dementia, cognitive change from baseline, blood pressure level, incidence and severity of side effects and quality of life. Main results Four trials including 15,936 hypertensive subjects were identified. Average age was 75.4 years. Mean blood pressure at entry across the studies was 171/86 mmHg. The combined result of the four trials reporting incidence of dementia indicated no significant difference between treatment and placebo (236/7767 versus 259/7660, Odds Ratio (OR) = 0.89, 95% CI 0.74, 1.07) and there was considerable heterogeneity between the trials. The combined results from the three trials reporting change in Mini Mental State Examination (MMSE) did not indicate a benefit from treatment (Weighted Mean Difference (WMD) = 0.42, 95% CI 0.30, 0.53). Both systolic and diastolic blood pressure levels were reduced significantly in the three trials assessing this outcome (WMD = -10.22, 95% CI -10.78, -9.66 for systolic blood pressure, WMD = -4.28, 95% CI -4.58, -3.98 for diastolic blood pressure). Three trials reported adverse effects requiring discontinuation of treatment and the combined results indicated no significant difference (OR = 1.01, 95% CI 0.92, 1.11). When analysed separately, however, more patients on placebo in Syst Eur 1997 were likely to discontinue treatment due to side effects; the converse was true in SHEP 1991. Quality of life data could not be analysed in the four studies. Analysis of the included studies in this review was problematic as many of the control subjects received antihypertensive treatment because their blood pressures exceeded pre-set values. In most cases the study became a comparison between the study drug against a usual antihypertensive regimen. Authors' conclusions There is no convincing evidence from the trials identified that blood pressure lowering in late-life prevents the development of dementia or cognitive impairment in hypertensive patients with no apparent prior cerebrovascular disease. There were significant problems identified with analysing the data, however, due to the number of patients lost to follow-up and the number of placebo patients who received active treatment. This introduced bias. More robust results may be obtained by conducting a meta-analysis using individual patient data.

The impact and recovery of asteroid 2008 TC 3

Abstract: On 6 October 2008, a small Earth-bound asteroid designated 2008 TC3 was discovered by the Catalina Sky Survey. Some 19 hours — and many astronomical observations — later it entered the atmosphere and disintegrated at 37 km altitude. No macroscopic fragments were expected to have survived but a dedicated search along the approach trajectory in a desert in northern Sudan has recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. The asteroid and meteorite reflectance spectra identify the asteroid as surface matter from a class 'F' asteroid, material so fragile that it was not previously represented in meteorite collections. To have recovered meteorites from a known class of asteroids is a coup on a par with a successful spacecraft sample-return mission — without the rocket science. On 6 October 2008, a small asteroid designated 2008 TC3 hit the Earth in northern Sudan. Jenniskens et al. searched along the approach trajectory and luckily found 47 bits of a meteorite named Almahata Sitta. Analysis reveals it to be a porous achondrite and a polymict ureilite, and so the asteroid was F-class (dark carbon-rich anomalous ureilites). In the absence of a firm link between individual meteorites and their asteroidal parent bodies, asteroids are typically characterized only by their light reflection properties, and grouped accordingly into classes1,2,3. On 6 October 2008, a small asteroid was discovered with a flat reflectance spectrum in the 554–995 nm wavelength range, and designated 2008 TC3 (refs 4–6). It subsequently hit the Earth. Because it exploded at 37 km altitude, no macroscopic fragments were expected to survive. Here we report that a dedicated search along the approach trajectory recovered 47 meteorites, fragments of a single body named Almahata Sitta, with a total mass of 3.95 kg. Analysis of one of these meteorites shows it to be an achondrite, a polymict ureilite, anomalous in its class: ultra-fine-grained and porous, with large carbonaceous grains. The combined asteroid and meteorite reflectance spectra identify the asteroid as F class3, now firmly linked to dark carbon-rich anomalous ureilites, a material so fragile it was not previously represented in meteorite collections.

Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons

Abstract: We present a technique for simultaneous focusing and energy selection of high-current, mega–electron volt proton beams with the use of radial, transient electric fields (10 7 to 10 10 volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.

Invading predatory crustacean Dikerogammarus villosus eliminates both native and exotic species.

Abstract: As the tempo of biological invasions increases, explanations and predictions of their impacts become more crucial. Particularly with regard to biodiversity, we require elucidation of interspeci¢ c behavioural interactions among invaders and natives. In freshwaters in The Netherlands, we show that the invasive Ponto-Caspian crustacean amphipod Dikerogammarus villosus is rapidly eliminating Gammarus duebeni , a native European amphipod, and Gammarus tigrinus , until now a spectacularly successful invader from North America. In the laboratory, survival of single (unguarded) female G.duebeni was signi¢ cantly lower when male D.villosus were free to roam as compared with isolated within microcosms. In addition, survival of paired (guarded) female G. duebeni was signi¢ cantly lower when male D.villosus as compared with male G.duebeni were present. D.villosus killed and consumed both recently moulted and, unusually, intermoult victims. Survival of G.tigrinus was signi¢ cantly lower when D.villosus were free to roam as compared with isolated within microcosms and, again, both moulted and intermoult victims were preyed upon. Male D.villosus were signi¢ cantly more predatory than were females, while female G.tigrinus were signi¢ cantly more often preyed upon than were males. Predation by D.villosus on both species occurred over a range of water conductivities, an environmental feature previously shown to promote amphipod coexistence. This predatory invader is predicted to reduce further the amphipod diversity in a range of freshwater habitats in Europe and North America.