SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Riemann L.) "

Sökning: WFRF:(Riemann L.)

  • Resultat 1-25 av 37
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Schael, S., et al. (författare)
  • Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
  • 2013
  • Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
  • Forskningsöversikt (refereegranskat)abstract
    • Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
  •  
2.
  • Schael, S, et al. (författare)
  • Precision electroweak measurements on the Z resonance
  • 2006
  • Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
  • Forskningsöversikt (refereegranskat)abstract
    • We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
  •  
3.
  •  
4.
  •  
5.
  •  
6.
  • Luo, Y. -W, et al. (författare)
  • Database of diazotrophs in global ocean : abundance, biomass and nitrogen fixation rates
  • 2012
  • Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 4:1, s. 47-73
  • Tidskriftsartikel (refereegranskat)abstract
    • Marine N-2 fixing microorganisms, termed di-azotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen ( N-2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes) and N-2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N-2 fixation rate in the global ocean is estimated to be 62 (52-73) Tg Nyr(-1) and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4-3.1) Tg C from cell counts and to 89 (43-150) Tg C from nifH- based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 +/- 9.2 Tg Nyr(-1), 18 +/- 1.8 Tg C and 590 +/- 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about +/- 70 %. It was recently established that the most commonly applied method used to measure N-2 fixation has underestimated the true rates. As a result, one can expect that future rate measurements will shift the mean N-2 fixation rate upward and may result in significantly higher estimates for the global N-2 fixation. The evolving database can nevertheless be used to study spatial and temporal distributions and variations of marine N-2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models, keeping in mind that future rate measurements may rise in the future.
  •  
7.
  •  
8.
  • Yager, P. L., et al. (författare)
  • A carbon budget for the Amundsen Sea Polynya, Antarctica: Estimating net community production and export in a highly productive polar ecosystem
  • 2016
  • Ingår i: Elementa-Science of the Anthropocene. - : University of California Press. - 2325-1026. ; 4
  • Tidskriftsartikel (refereegranskat)abstract
    • Polynyas, or recurring areas of seasonally open water surrounded by sea ice, are foci for energy and material transfer between the atmosphere and the polar ocean. They are also climate sensitive, with both sea ice extent and glacial melt influencing their productivity. The Amundsen Sea Polynya (ASP) is the greenest polynya in the Southern Ocean, with summertime chlorophyll a concentrations exceeding 20 mu g L-1. During the Amundsen Sea Polynya International Research Expedition (ASPIRE) in austral summer 2010-11, we aimed to determine the fate of this high algal productivity. We collected water column profiles for total dissolved inorganic carbon (DIC) and nutrients, particulate and dissolved organic matter, chlorophyll a, mesozoo-plankton, and microbial biomass to make a carbon budget for this ecosystem. We also measured primary and secondary production, community respiration rates, vertical particle flux and fecal pellet production and grazing. With observations arranged along a gradient of increasing integrated dissolved inorganic nitrogen drawdown (Delta DIN; 0.027-0.74 mol N m(-2)), changes in DIC in the upper water column (ranging from 0.2 to 4.7 mol C m(-2)) and gas exchange (0-1.7 mol C m(-2)) were combined to estimate early season net community production (sNCP; 0.2-5.9 mol C m(-2)) and then compared to organic matter inventories to estimate export. From a phytoplankton bloom dominated by Phaeocystis antarctica, a high fraction (up to similar to 60%) of sNCP was exported to sub-euphotic depths. Microbial respiration remineralized much of this export in the mid waters. Comparisons to short-term (2-3 days) drifting traps and a year-long moored sediment trap capturing the downward flux confirmed that a relatively high fraction (3-6%) of the export from similar to 100 m made it through the mid waters to depth. We discuss the climate-sensitive nature of these carbon fluxes, in light of the changing sea ice cover and melting ice sheets in the region.
  •  
9.
  • Yager, P. L., et al. (författare)
  • ASPIRE The Amundsen Sea Polynya International Research Expedition
  • 2012
  • Ingår i: Oceanography. - : The Oceanography Society. - 1042-8275. ; 25:3, s. 40-53
  • Tidskriftsartikel (refereegranskat)abstract
    • In search of an explanation for some of the greenest waters ever seen in coastal Antarctica and their possible link to some of the fastest melting glaciers and declining summer sea ice, the Amundsen Sea Polynya International Research Expedition (ASPIRE) challenged the capabilities of the US Antarctic Program and RVIB Nathaniel B. Palmer during Austral summer 2010-2011. We were well rewarded by both an extraordinary research platform and a truly remarkable oceanic setting. Here we provide further insights into the key questions that motivated our sampling approach during ASPIRE and present some preliminary findings, while highlighting the value of the Palmer for accomplishing complex, multifaceted oceanographic research in such a challenging environment.
  •  
10.
  •  
11.
  • Tahmasian, Masoud, et al. (författare)
  • ENIGMA-Sleep : Challenges, opportunities, and the road map
  • 2021
  • Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 30:6
  • Forskningsöversikt (refereegranskat)abstract
    • Neuroimaging and genetics studies have advanced our understanding of the neurobiology of sleep and its disorders. However, individual studies usually have limitations to identifying consistent and reproducible effects, including modest sample sizes, heterogeneous clinical characteristics and varied methodologies. These issues call for a large-scale multi-centre effort in sleep research, in order to increase the number of samples, and harmonize the methods of data collection, preprocessing and analysis using pre-registered well-established protocols. The Enhancing NeuroImaging Genetics through Meta-Analysis (ENIGMA) consortium provides a powerful collaborative framework for combining datasets across individual sites. Recently, we have launched the ENIGMA-Sleep working group with the collaboration of several institutes from 15 countries to perform large-scale worldwide neuroimaging and genetics studies for better understanding the neurobiology of impaired sleep quality in population-based healthy individuals, the neural consequences of sleep deprivation, pathophysiology of sleep disorders, as well as neural correlates of sleep disturbances across various neuropsychiatric disorders. In this introductory review, we describe the details of our currently available datasets and our ongoing projects in the ENIGMA-Sleep group, and discuss both the potential challenges and opportunities of a collaborative initiative in sleep medicine.
  •  
12.
  •  
13.
  • Sookman, D., et al. (författare)
  • Knowledge and competency standards for specialized cognitive behavior therapy for adult Obsessive-Compulsive Disorder: Phase two series by the International Accreditation Task Force of The Canadian Institute for OCD (CIOCD, www.ciocd.ca)
  • 2021
  • Ingår i: Psychiatry Research. - : Elsevier BV. - 1872-7123 .- 0165-1781. ; 303
  • Tidskriftsartikel (refereegranskat)abstract
    • Obsessive-Compulsive Disorder (OCD) is a leading cause of disability world-wide (World Health Organization, 2008). Treatment of OCD is a specialized field whose aim is recovery from illness for as many patients as possible. The evidence-based psychotherapeutic treatment for OCD is specialized cognitive behavior therapy (CBT, NICE, 2005, Koran and Simpson, 2013). However, these treatments are not accessible to many sufferers around the world. Currently available guidelines for care are deemed to be essential but insufficient because of highly variable clinician knowledge and competencies specific to OCD. The phase two mandate of the 14 nation International OCD Accreditation Task Force (ATF) created by the Canadian Institute for Obsessive Compulsive Disorders is development of knowledge and competency standards for specialized treatments for OCD through the lifespan deemed by experts to be foundational to transformative change in this field. This paper presents knowledge and competency standards for specialized CBT for adult OCD developed to inform, advance, and offer a model for clinical practice and training for OCD. During upcoming ATF phases three and four criteria and processes for training in specialized treatments for OCD through the lifespan for certification (individuals) and accreditation (sites) will be developed based on the ATF standards
  •  
14.
  • Alonso-Sáez, Laura, et al. (författare)
  • Role for urea in nitrification by polar marine Archaea
  • 2012
  • Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 109:44, s. 17989-17994
  • Tidskriftsartikel (refereegranskat)abstract
    • Despite the high abundance of Archaea in the global ocean, their metabolism and biogeochemical roles remain largely unresolved. We investigated the population dynamics and metabolic activity of Thaumarchaeota in polar environments, where these microorganisms are particularly abundant and exhibit seasonal growth. Thaumarchaeota were more abundant in deep Arctic and Antarctic waters and grew throughout the winter at surface and deeper Arctic halocline waters. However, in situ single-cell activity measurements revealed a low activity of this group in the uptake of both leucine and bicarbonate (<5% Thaumarchaeota cells active), which is inconsistent with known heterotrophic and autotrophic thaumarchaeal lifestyles. These results suggested the existence of alternative sources of carbon and energy. Our analysis of an environmental metagenome from the Arctic winter revealed that Thaumarchaeota had pathways for ammonia oxidation and, unexpectedly, an abundance of genes involved in urea transport and degradation. Quantitative PCR analysis confirmed that most polar Thaumarchaeota had the potential to oxidize ammonia, and a large fraction of them had urease genes, enabling the use of urea to fuel nitrification. Thaumarchaeota from Arctic deep waters had a higher abundance of urease genes than those near the surface suggesting genetic differences between closely related archaeal populations. In situ measurements of urea uptake and concentration in Arctic waters showed that small-sized prokaryotes incorporated the carbon from urea, and the availability of urea was often higher than that of ammonium. Therefore, the degradation of urea may be a relevant pathway for Thaumarchaeota and other microorganisms exposed to the low-energy conditions of dark polar waters.
  •  
15.
  •  
16.
  • Baglioni, Chiara, et al. (författare)
  • The European Academy for Cognitive Behavioural Therapy for Insomnia : An initiative of the European Insomnia Network to promote implementation and dissemination of treatment
  • 2020
  • Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 29:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Insomnia, the most prevalent sleep disorder worldwide, confers marked risks for both physical and mental health. Furthermore, insomnia is associated with considerable direct and indirect healthcare costs. Recent guidelines in the US and Europe unequivocally conclude that cognitive behavioural therapy for insomnia (CBT-I) should be the first-line treatment for the disorder. Current treatment approaches are in stark contrast to these clear recommendations, not least across Europe, where, if any treatment at all is delivered, hypnotic medication still is the dominant therapeutic modality. To address this situation, a Task Force of the European Sleep Research Society and the European Insomnia Network met in May 2018. The Task Force proposed establishing a European CBT-I Academy that would enable a Europe-wide system of standardized CBT-I training and training centre accreditation. This article summarizes the deliberations of the Task Force concerning definition and ingredients of CBT-I, preconditions for health professionals to teach CBT-I, the way in which CBT-I should be taught, who should be taught CBT-I and to whom CBT-I should be administered. Furthermore, diverse aspects of CBT-I care and delivery were discussed and incorporated into a stepped-care model for insomnia.
  •  
17.
  •  
18.
  • Dinasquet, Julie, et al. (författare)
  • Cascading effects of the ctenophore Mnemiopsis leidyi on the planktonic food web in a nutrient-limited estuarine system
  • 2012
  • Ingår i: Marine Ecology Progress Serie. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 460, s. 49-61
  • Tidskriftsartikel (refereegranskat)abstract
    • Increasing biomasses of gelatinous zooplankton presumably have major implications for the structure and function of marine food webs at large; however, current data on lower trophic levels are scarce, as most studies have focused on the immediate effects on zooplankton and fish larvae only. We examined the short-term impact of larvae and adults of the invasive ctenophore Mnemiopsis leidyi on a summer planktonic food web in the estuarine southern Baltic Sea, with special emphasis on the microbial loop. Grazing by M. leidyi reduced the mesozooplankton biomass, followed by increased dinoflagellate biomass in treatments with M. leidyi. While chlorophyll a increased most in the treatments with M. leidyi, small phytoplankton and ciliates decreased in all treatments. M. leidyi had a slight effect on bacterial abundance, but not on bacterial production, ectoenzymatic activities, or community composition. Undetectable levels of phosphate and a gradual accumulation of dissolved organic carbon during the experiment suggested a malfunctioning microbial loop scenario. The experiment shows that direct and indirect short-term effects of M. leidyi on the estuarine food web are limited to higher trophic levels and indicates that top-down and bottom-up consequences of M. leidyi expansions on the microbial loop will likely depend on local nutrient conditions.
  •  
19.
  •  
20.
  •  
21.
  • Gruen, E., et al. (författare)
  • Ulysses Dust Detection System V3.1
  • 2010
  • Ingår i: NASA Planetary Data System. ; 140
  • Tidskriftsartikel (refereegranskat)abstract
    • This data set contains the data from the Ulysses dust detector system (UDDS) from start of mission through the end of mission, 1990-2007. (As the dust detector was turned off after Nov. 30, 2007, this is the last date for which UDDS data is recorded.) Included are the dust impact data, noise data, laboratory calibration data, and location and orientation of the spacecraft and instrument.
  •  
22.
  • Happel, E. M., et al. (författare)
  • Effects of allochthonous dissolved organic matter input on microbial composition and nitrogen-cycling genes at two contrasting estuarine sites
  • 2019
  • Ingår i: FEMS Microbiology Ecology. - : Oxford University Press. - 0168-6496 .- 1574-6941. ; 95:9
  • Tidskriftsartikel (refereegranskat)abstract
    • Heterotrophic bacteria are important drivers of nitrogen (N) cycling and the processing of dissolved organic matter (DOM). Projected increases in precipitation will potentially cause increased loads of riverine DOM to the Baltic Sea and likely affect the composition and function of bacterioplankton communities. To investigate this, the effects of riverine DOM from two different catchment areas (agricultural and forest) on natural bacterioplankton assemblages from two contrasting sites in the Baltic Sea were examined. Two microcosm experiments were carried out, where the community composition (16S rRNA gene sequencing), the composition of a suite of N-cycling genes (metagenomics) and the abundance and transcription of ammonia monooxygenase (amoA) genes involved in nitrification (quantitative PCR) were investigated. The river water treatments evoked a significant response in bacterial growth, but the effects on overall community composition and the representation of N-cycling genes were limited. Instead, treatment effects were reflected in the prevalence of specific taxonomic families, specific N-related functions and in the transcription of amoA genes. The study suggests that bacterioplankton responses to changes in the DOM pool are constrained to part of the bacterial community, whereas most taxa remain relatively unaffected.
  •  
23.
  •  
24.
  •  
25.
  • Hosia, Aino, et al. (författare)
  • Autumnal bottom-up and top-down impacts of Cyanea capillata: a mesocosm study
  • 2015
  • Ingår i: Journal of Plankton Research. - : Oxford University Press (OUP). - 0142-7873 .- 1464-3774. ; 37:5, s. 1042-1055
  • Tidskriftsartikel (refereegranskat)abstract
    • Jellyfish are effective predators on mesozooplankton and release large amounts of dissolved organic matter. Nevertheless, jellyfish initiated trophic cascades and bottom-up influences impacting lower trophic levels have received limited attention. We conducted a mesocosm experiment to quantify simultaneous top-down and bottom-up effects of a common jellyfish, Cyanea capillata, in a natural plankton community during autumn. Treatments were 0, 2 or 5 jellyfish per 2.5 m3 mesocosm, four replicates each, with initial additions of inorganic nutrients. Primary and bacterial production, species abundance and composition of several trophic levels and nutrient and carbon dynamics were followed during the 8-day experiment. Multivariate statistics and generalized additive mixed modelling were applied to test whether jellyfish carbon concentration (0–1.26 mg jellyC L−1) in the mesocosms affected the variables monitored. Unexpected negligible predatory impact of jellyfish on mesozooplankton was observed, potentially related to jellyfish senescence. Community compositions of bacteria, phytoplankton and mesozooplankton changed with time, but did not differ between treatments. However, nutrient regeneration by jellyfish was evident, and jellyfish had a positive impact on total and specific bacterial production, total primary production and the >10 µm chlorophyll a fraction. Bottom-up influences from abundant jellyfish could thus stimulate productivity in nutrient depleted autumnal surface waters.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-25 av 37

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy