237 research outputs found

    A Quark-Antiquark Condensate in Three-Dimensional QCD

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    Three-dimensional lattice QCD is studied by Monte Carlo simulations within the quenched approximation. At zero temperature a quark-antiquark condensate is observed in the limit of vanishing quark masses. The condensate vanishes continuously at the finite-temperature deconfinement phase transition of the theory. A natural interpretation of this phenomenon in the full theory with dynamical quarks is in terms of the spontaneous flavor symmetry breaking U(Nf)U(Nf/2)×U(Nf/2)U(N_f) \to U(N_f/2)\times U(N_f/2). In addition, the spectrum of low-lying Dirac operator eigenvalues is computed and found to be consistent with a flat distribution at zero temperature, in agreement with analytical predictions.Comment: Extensive revision of the original version. 11 pages, 6 figures included as EPS files. The problem with figure encapsulation fixe

    Biological activity of glucosinolate derived compounds isolated from seed meal of Brassica crops and evaluated as plant and food protection agents

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    Glucosinolates are amino acid derived allelochemicals characteristic of plants of the order Capparales. These compounds are present in seeds of agriculturally common Brassica crops in varying quantities depending on the species (ref). The use of the remaining seed cake after oil extraction has traditionally been limited by the concentration of these compounds. However, the extraction of glucosinolates from seed meal is nowadays possible and it further contributes to an increased quality of the seed meal for feed (Sørensen et al., this conference). Glucosinolates are hydrolysed by endogenous enzymes (myrosinases; EC 3.2.1.147) and a number of compounds are produced depending on the parent glucosinolate and the environmental conditions.1 Among these compounds, oxazolidine-2-thiones are known for their antinutritional effects on monogastric animals, whereas isothiocyanates are fungicidal, nematocidal and herbicidal.2,3 The possibility for using glucosinolates as precursors for environmental friendly biocides therefore exists, which could contribute to increase the value of the Brassica seed meal

    Predicting ultimate loads for wind turbine design

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    Produktorienteret miljøindsats i landbrugssektoren - forudsætninger

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    For at styrke den produktorienterede miljøindsats i landbruget nedsatte Miljøstyrelsen primo 2003 et produktkædepanel for landbrugsområdet. Panelets primære mål er at fremme udvikling og afsætning af landbrugsprodukter, der set i et livscyklusperspektiv ("fra jord til jord") er mindre miljøbelastende end tilsvarende traditionelle produkter. Som fundament for panelets arbejde er udarbejdet denne rapport, som beskriver de eksisterende forudsætninger for en produktorienteret indsats i sektoren - i form af en kortlægning af relevante projekter/tiltag. Denne rapport har dannet udgangspunkt for udarbejdelsen af et såkaldt fremsyn på området, som er publiceret særskilt. Fremsynet og information om panelets arbejde i øvrigt kan fås på www.produktpanel-landbrug.dk. En produktorienteret indsats vil altid være et supplement til de eksisterende overordnede reguleringer af samfundets adfærd, forbrug og udledninger. Vi vil stadig i fremtiden opleve berettiget miljøarbejde, der tager udgangspunkt i en konkret produktion eller proces eller i ønsket om at reducere en arealbelastning. Med produktorientering følger en anderledes og mere nuanceret opfattelse af, hvad der er "godt og dårligt" for miljøet, hvilke områder, der skal prioriteres i fødevaresektorens miljøindsats, og hvad miljøarbejdet kan omfatte i alle led i fødevarernes produktkæde. Et produktorienteret miljøarbejde stiller krav til og udfordrer alle aktører i produktkæderne. Der skal ikke alene udveksles og håndteres oplysninger om produktets miljøpåvirkning bagud og fremad i produktkæden, men der skal også ageres på baggrund af de erkendelser, denne udveksling af oplysninger giver anledning til. Helhedsorienteringen skaber også muligheder for at synliggøre og dokumentere valg undervejs i produktkæden. Produktorientering giver dermed en enestående mulighed for aktører/virksomheder for at dokumentere adfærd og valg overfor aftagere (herunder forbrugeren). Også for landbrugs- og gartnerierhvervet er produktorienteringen en udfordring. En kvalificeret diskussion af muligheder og perspektiver i produktorienteringen i landbrugserhvervet er derfor langt fra kun et spørgsmål om værktøjer, opgørelsesmetoder og mulighederne for afsætning af miljødokumenterede varer. Produktorienteringen er i langt højere grad den ramme, hvori f.eks. nedenstående spørgsmål kan diskuteres: Hvilke langsigtede scenarier for landbrugserhvervet er tænkelige? Hvilke strategier kan anlægges for erhvervsudvikling, forskning, kompetenceudvikling etc. for bedst muligt at sigte på de mest attraktive scenarier? Hvordan bringes aktørerne i spil, og hvordan skal ansvar fordeles? De hidtidige erfaringer med produktorientering viser, at en væsentlig forudsætning for succes er åbenhed og kommunikation i produktkæderne

    Review of Speculative "Disaster Scenarios" at RHIC

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    We discuss speculative disaster scenarios inspired by hypothetical new fundamental processes that might occur in high energy relativistic heavy ion collisions. We estimate the parameters relevant to black hole production; we find that they are absurdly small. We show that other accelerator and (especially) cosmic ray environments have already provided far more auspicious opportunities for transition to a new vacuum state, so that existing observations provide stringent bounds. We discuss in most detail the possibility of producing a dangerous strangelet. We argue that four separate requirements are necessary for this to occur: existence of large stable strangelets, metastability of intermediate size strangelets, negative charge for strangelets along the stability line, and production of intermediate size strangelets in the heavy ion environment. We discuss both theoretical and experimental reasons why each of these appears unlikely; in particular, we know of no plausible suggestion for why the third or especially the fourth might be true. Given minimal physical assumptions the continued existence of the Moon, in the form we know it, despite billions of years of cosmic ray exposure, provides powerful empirical evidence against the possibility of dangerous strangelet production.Comment: 28 pages, REVTeX; minor revisions for publication (Reviews of Modern Physics, ca. Oct. 2000); email to [email protected]

    Results of the Search for Strange Quark Matter and Q-balls with the SLIM Experiment

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    The SLIM experiment at the Chacaltaya high altitude laboratory was sensitive to nuclearites and Q-balls, which could be present in the cosmic radiation as possible Dark Matter components. It was sensitive also to strangelets, i.e. small lumps of Strange Quark Matter predicted at such altitudes by various phenomenological models. The analysis of 427 m^2 of Nuclear Track Detectors exposed for 4.22 years showed no candidate event. New upper limits on the flux of downgoing nuclearites and Q-balls at the 90% C.L. were established. The null result also restricts models for strangelets propagation through the Earth atmosphere.Comment: 14 pages, 11 EPS figure

    A population-based study on the prognostic impact of primary tumor sidedness in patients with peritoneal metastases from colon cancer

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    Primary tumor location is an established prognostic factor in patients with (metastatic) colon cancer. Colon tumors can be divided into left-sided and right-sided tumors. The aim of this study was to determine the impact of primary tumor location on treatment and overall survival (OS) in patients with peritoneal metastases (PM) from colon cancer. This study is a retrospective, population-based cohort study. Records of patients diagnosed with colon cancer and synchronous PM, from 1995 through 2016, were retrieved from the Netherlands Cancer Registry (NCR). Data on diagnosis, staging, and treatment were extracted from the medical records by specifically trained NCR personnel. Information on survival status was updated annually using a computerized link with the national civil registry. In total, 7930 patients were included in this study; 4555 (57.4%) had a right-sided and 3375 (42.6%) had a left-sided primary tumor. In multivariable analysis right-sided primary tumor was associated with worse OS (HR: 1.11, 95% CI 1.03-1.19, P = .007). Of all patients diagnosed with PM, 564 (7.1%) underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). Patients with left-sided primary tumors were more often candidates for CRS-HIPEC (6.5% vs. 8.0%, P = .008). OS of patients with right- and left-sided tumors who underwent CRS-HIPEC did not significantly differ. In conclusion, primary right-sided colon cancer was an independent prognostic factor for decreased OS in patients diagnosed with synchronous PM. In patients treated with CRS-HIPEC location of the primary tumor did not influence survival

    Muon reconstruction performance of the ATLAS detector in proton–proton collision data at √s = 13 TeV

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    This article documents the performance of the ATLAS muon identification and reconstruction using the LHC dataset recorded at √s = 13 TeV in 2015. Using a large sample of J/ψ→μμ and Z→μμ decays from 3.2 fb−1 of pp collision data, measurements of the reconstruction efficiency, as well as of the momentum scale and resolution, are presented and compared to Monte Carlo simulations. The reconstruction efficiency is measured to be close to 99% over most of the covered phase space (|η| 2.2, the pT resolution for muons from Z→μμ decays is 2.9 % while the precision of the momentum scale for low-pT muons from J/ψ→μμ decays is about 0.2%

    Measurement of the dependence of transverse energy production at large pseudorapidity on the hard-scattering kinematics of proton-proton collisions at √s=2.76 TeV with ATLAS

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    The relationship between jet production in the central region and the underlying-event activity in a pseudorapidity-separated region is studied in 4.0 pb-1 of s=2.76 TeV pp collision data recorded with the ATLAS detector at the LHC. The underlying event is characterised through measurements of the average value of the sum of the transverse energy at large pseudorapidity downstream of one of the protons, which are reported here as a function of hard-scattering kinematic variables. The hard scattering is characterised by the average transverse momentum and pseudorapidity of the two highest transverse momentum jets in the event. The dijet kinematics are used to estimate, on an event-by-event basis, the scaled longitudinal momenta of the hard-scattered partons in the target and projectile beam-protons moving toward and away from the region measuring transverse energy, respectively. Transverse energy production at large pseudorapidity is observed to decrease with a linear dependence on the longitudinal momentum fraction in the target proton and to depend only weakly on that in the projectile proton. The results are compared to the predictions of various Monte Carlo event generators, which qualitatively reproduce the trends observed in data but generally underpredict the overall level of transverse energy at forward pseudorapidity
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