| 1. |
- Abazov, M, et al.
(author)
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Evidence of WW and WZ Production with lepton plus jets Final States in pp Collisions at root s=1.96 TeV
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:16, s. 161801-
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Journal article (peer-reviewed)abstract
- We present first evidence for WW+WZ production in lepton+jets final states at a hadron collider. The data correspond to 1.07 fb(-1) of integrated luminosity collected with the D0 detector at the Fermilab Tevatron in pp collisions at root s=1.96 TeV. The observed cross section for WW+WZ production is 20.2 +/- 4.5 pb, consistent with the standard model and more precise than previous measurements in fully leptonic final states. The probability that background fluctuations alone produce this excess is < 5.4x10(-6), which corresponds to a significance of 4.4 standard deviations.
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| 2. |
- Abazov, M, et al.
(author)
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Search for Long-Lived Charged Massive Particles with the D0 Detector
- 2009
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:16, s. 161802-
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Journal article (peer-reviewed)abstract
- We search for long-lived charged massive particles using 1.1 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron pp Collider. Time-of-flight information is used to search for pair produced long-lived tau sleptons, gauginolike charginos, and Higgsino-like charginos. We find no evidence of a signal and set 95% C.L. cross section upper limits for staus, which vary from 0.31 to 0.04 pb for stau masses between 60 and 300 GeV. We also set lower mass limits of 206 GeV (171 GeV) for pair produced charged gauginos (Higgsinos).
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| 3. |
- Barthelmy, S D, et al.
(author)
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An origin for short gamma-ray bursts unassociated with current star formation
- 2005
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 438, s. 994-996
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Journal article (peer-reviewed)abstract
- Two short (< 2 s) gamma-ray bursts (GRBs) have recently been localized(1-4) and fading afterglow counterparts detected(2-4). The combination of these two results left unclear the nature of the host galaxies of the bursts, because one was a star-forming dwarf, while the other was probably an elliptical galaxy. Here we report the X-ray localization of a short burst (GRB 050724) with unusual gamma-ray and X-ray properties. The X-ray afterglow lies off the centre of an elliptical galaxy at a redshift of z = 0.258 (ref. 5), coincident with the position determined by ground-based optical and radio observations(6-8). The low level of star formation typical for elliptical galaxies makes it unlikely that the burst originated in a supernova explosion. A supernova origin was also ruled out for GRB 050709 ( refs 3, 31), even though that burst took place in a galaxy with current star formation. The isotropic energy for the short bursts is 2 - 3 orders of magnitude lower than that for the long bursts. Our results therefore suggest that an alternative source of bursts - the coalescence of binary systems of neutron stars or a neutron star-black hole pair - are the progenitors of short bursts.
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| 4. |
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| 5. |
- Högberg, Peter, et al.
(author)
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High temporal resolution tracing of photosynthate carbon from the tree canopy to forest soil microorganisms
- 2008
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In: New Phytologist. - : New Phytologist Trust. - 0028-646X .- 1469-8137. ; 177:1, s. 220-228
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Journal article (peer-reviewed)abstract
- • Half of the biological activity in forest soils is supported by recent tree photosynthate, but no study has traced in detail this flux of carbon from the canopy to soil microorganisms in the field.• Using 13CO2, we pulse-labelled over 1.5 h a 50-m2 patch of 4-m-tall boreal Pinus sylvestris forest in a 200-m3 chamber.• Tracer levels peaked after 24 h in soluble carbohydrates in the phloem at a height of 0.3 m, after 2–4 d in soil respiratory efflux, after 4–7 d in ectomycorrhizal roots, and after 2–4 d in soil microbial cytoplasm. Carbon in the active pool in needles, in soluble carbohydrates in phloem and in soil respiratory efflux had half-lives of 22, 17 and 35 h, respectively. Carbon in soil microbial cytoplasm had a half-life of 280 h, while the carbon in ectomycorrhizal root tips turned over much more slowly. Simultaneous labelling of the soil with showed that the ectomycorrhizal roots, which were the strongest sinks for photosynthate, were also the most active sinks for soil nitrogen.• These observations highlight the close temporal coupling between tree canopy photosynthesis and a significant fraction of soil activity in forests.
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| 6. |
- Lee, S. S., et al.
(author)
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Sensitivity of aerosol and cloud effects on radiation to cloud types: comparison between deep convective clouds and warm stratiform clouds over one-day period
- 2009
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In: Atmospheric Chemistry and Physics. - 1680-7324. ; 9:7, s. 2555-2575
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Journal article (peer-reviewed)abstract
- Cloud and aerosol effects on radiation in two contrasting cloud types, a deep mesoscale convective system (MCS) and warm stratocumulus clouds, are simulated and compared. At the top of the atmosphere, 45-81% of shortwave cloud forcing (SCF) is offset by longwave cloud forcing (LCF) in the MCS, whereas warm stratiform clouds show the offset of less than similar to 20%. 28% of increased negative SCF is offset by increased LCF with increasing aerosols in the MCS at the top of the atmosphere. However, the stratiform clouds show the offset of just around 2-5%. Ice clouds as well as liquid clouds play an important role in the larger offset in the MCS. Lower cloud-top height and cloud depth, characterizing cloud types, lead to the smaller offset of SCF by LCF and the offset of increased negative SCF by increased LCF at high aerosol in stratocumulus clouds than in the MCS. Supplementary simulations show that this dependence of modulation of LCF on cloud depth and cloud-top height is also simulated among different types of convective clouds.
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| 7. |
- Benedict, Catherine, et al.
(author)
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The CBF1-dependent low temperature signalling pathway, regulon and increase in freeze tolerance are conserved in Populus spp
- 2006
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In: Plant, Cell and Environment. - Oxford : Blackwell Scientific Publications Ltd. - 0140-7791 .- 1365-3040. ; 29:7, s. 1259-1272
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Journal article (peer-reviewed)abstract
- The meristematic tissues of temperate woody perennials must acclimate to freezing temperatures to survive the winter and resume growth the following year. To determine whether the C-repeat binding factor (CBF) family of transcription factors contributing to this process in annual herbaceous species also functions in woody perennials, we investigated the changes in phenotype and transcript profile of transgenic Populus constitutively expressing CBF1 from Arabidopsis (AtCBF1). Ectopic expression of AtCBF1 was sufficient to significantly increase the freezing tolerance of non-acclimated leaves and stems relative to wild-type plants. cDNA microarray experiments identified genes up-regulated by ectopic AtCBF1 expression in Populus, demonstrated a strong conservation of the CBF regulon between Populus and Arabidopsis and identified differences between leaf and stem regulons. We studied the induction kinetics and tissue specificity of four CBF paralogues identified from the Populus balsamifera subsp. trichocarpa genome sequence (PtCBFs). All four PtCBFs are cold-inducible in leaves, but only PtCBF1 and PtCBF3 show significant induction in stems. Our results suggest that the central role played by the CBF family of transcriptional activators in cold acclimation of Arabidopsis has been maintained in Populus. However, the differential expression of the PtCBFs and differing clusters of CBF-responsive genes in annual (leaf) and perennial (stem) tissues suggest that the perennial-driven evolution of winter dormancy may have given rise to specific roles for these 'master-switches' in the different annual and perennial tissues of woody species.
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| 8. |
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| 9. |
- Birznieks, Ingvars, et al.
(author)
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Slowly adapting mechanoreceptors in the borders of the human fingernail encode fingertip forces
- 2009
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In: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 29:29, s. 9370-9379
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Journal article (peer-reviewed)abstract
- There are clusters of slowly adapting (SA) mechanoreceptors in the skin folds bordering the nail. These "SA-IInail" afferents, which constitute nearly one fifth of the tactile afferents innervating the fingertip, possess the general discharge characteristics of slowly adapting type II (SA-II) tactile afferents located elsewhere in the glabrous skin of the human hand. Little is known about the signals in the SA-IInail afferents when the fingertips interact with objects. Here we show that SA-IInail afferents reliably respond to fingertip forces comparable to those arising in everyday manipulations. Using a flat stimulus surface, we applied forces to the finger pad while recording impulse activity in 17 SA-IInail afferents. Ramp-and-hold forces (amplitude 4 N, rate 10 N/s) were applied normal to the skin, and at 10, 20, or 30 degrees from the normal in eight radial directions with reference to the primary site of contact (25 force directions in total). All afferents responded to the force stimuli, and the responsiveness of all but one afferents was broadly tuned to a preferred direction of force. The preferred directions among afferents were distributed all around the angular space, suggesting that the population of SA-IInail afferents could encode force direction. We conclude that signals in the population of SA-IInail afferents terminating in the nail walls contain vectorial information about fingertip forces. The particular tactile features of contacted surfaces would less influence force-related signals in SA-IInail afferents than force-related signals present in afferents terminating in the volar skin areas that directly contact objects.
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| 10. |
- Whelan, M. J., et al.
(author)
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The behaviour of linear alkyl benzene sulphonate under direct discharge conditions in Vientiane, Lao PDR
- 2007
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In: Water Research. - 0043-1354 .- 1879-2448. ; 41:20, s. 4730-4740
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Journal article (peer-reviewed)abstract
- Direct discharge of untreated sewage to surface waters is a common practice in many parts of the world. However, relatively little is known about the behaviour of synthetic organic pollutants under these conditions. This paper describes a sampling campaign designed to track changes in water quality in a surface water system in Vientiane (Lao PDR) receiving significant quantities of untreated waste water. The study was based on following in-channel transport using a fluorescent tracer injected as a pulse, with a focus on the anionic surfactant linear alkylbenzene sulphonate (LAS) and ammonia. Water samples were collected at a number of stations with sampling times estimated to coincide with solute time-of-travel. The reduction in LAS concentration with flow-time could be approximated by first-order kinetics with a half life of about 7 h. Free ammonia concentrations decreased more slowly than LAS and remained above the level believed to be toxic for sensitive aquatic species along the entire channel. Changes in the ratios of LAS alkyl chain homologues to total LAS concentrations suggest a preferential removal of longer chain lengths. The role of biodegradation in the removal of LAS was confirmed by the presence of LAS metabolites (sulphophenylcarboxylates, SPCs) which increased systematically (as a fraction of LAS remaining) with flow-time.
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