691 research outputs found
Biologisk recipientkontroll vid Forsmarks kärnkraftverk
Denna rapport sammanfattar långsiktiga och pågående trender ikustvattenmiljön utanför Forsmarks kärnkraftverk från mitten av 1970-taletfram till och med år 2012. Resultaten baseras på de fältundersökningar somutförs inom kärnkraftverkets kontrollprogram för att följa effekter avkylvattenanvändning på fisk, fågel och bottenfauna.Vid Forsmarks kärnkraftverk pumpas stora mängder brackvatten genomkraftverket för att kyla kondensorerna. Efter användning pumpas detanvända kylvattnet ut i närrecipienten, som får en temperaturhöjning medcirka 7-9°C. Kylvattenhanteringen har en direkt miljöpåverkan genom attdet havsvatten som används innehåller levande organismer som dras med ini systemet, eller filtreras bort vid intaget och dör. Det uppvärmda kylvattensom når närrecipienten har därtill effekter på djurens fysiologi, födotillgångoch beteendemönster, vilket i sin tur kan påverka deras tillväxt ochreproduktion. Dessa förändringar är väl dokumenterade under de år somkontrollprogrammet har pågått, framförallt när det gäller fisk. I rapportenpresenteras trender i utvecklingen över tid hos fisk, bottenfauna och fågel.Data jämförs där det är möjligt med motsvarande trender i referensområdensamt i andra delar av Bottenhavet och Östersjön.En stor del av de förändringar som observerats i Forsmarks skärgårdunder senare år kan sannolikt sammankopplas med kylvattenutflödet, isynnerhet efter år 2004 när det galler som tidigare hindrade fiskar från attvandra in och ut ur Biotestsjön togs bort. Detta syns som en ökad invandringav lekfisk i Biotestsjön och en tillkomst av arter som inte funnits där pålänge. Samtidigt ses förändrade tillväxtmönster hos abborre i Biotestsjönsamt utanför, i Forsmarks skärgård. I viss mån ses även förändradeutbredningsmönster hos sjöfågel som skulle kunna kopplas till förändradfödotillgång. För bottenfauna kan man inte avgöra om det finns mönster, pågrund av avsaknad av data under senare år.Resultaten antyder att en större del av fiskbestånden i Forsmarks skärgårdän tidigare är beroende av att Biotestsjön är en fungerande miljö förreproduktion och tillväxt. Detta är positivt så länge förhållandena iBiotestsjön och övriga områden som påverkas av kylvattenutsläpp ärgynnsamma, men negativt för omgivande skärgård om rekryteringen i dessaområden inte skulle fungera, eller om fiskens hälsa skulle påverkas. Dessaaspekter blir särskilt aktuella i och med den planerade effekthöjningen vidForsmarks kärnkraftverk, som sannolikt skulle kunna accentuera deobserverade effekterna, samt den planerade byggnaden av ett slutförvar, om denna påverkar tillgången på alternativa rekryteringsmiljöer för fisk inärområdet.Dödligheten i silstationen är fortsatt hög, om än med stormellanårsvariation i antal och artsammansättning. Mätningar vid silstationenvisar dock på en ökad dödlighet av ål, som inte kan förklaras av generellauppgångar i beståndet. Ökningen är troligen en effekt av att mer ål äntidigare vistas i Forsmarks skärgård, vilket skulle kunna bero på enanlockning av ål till området för kylvattenutsläpp.En annan förändring som inträffat under senare år är att en nyintroducerad art, musslan Mytilopsis leucopheata, har observerats i områdetsedan 2011. Arten har orsakat problem i kylvattenvägarna i andrakärnkraftverk i Östersjön, och områden med förhöjd vattentemperatur hartidigare identifierats som potentiella plattformar för fortsatt etablering avarten i andra områden
Critical behavior of Ginzburg-Landau model coupled to massless Dirac fermions
We point out interesting effects of additional massless Dirac fermions with
N_F colors upon the critical behavior of the Ginzburg-Landau model. For
increasing N_F, the model is driven into the type II regime of
superconductivity. The critical exponents are given as a function of N_F.Comment: RevTex4, 4 pages, 1 figure; author information and latest update to
this paper at http://www.physik.fu-berlin.de/~kleinert/institution.html;
version 2: new references and comments on chiral symmetry breaking adde
Modelling the hypothetical methane-leakage in a shale-gas project and the impact on groundwater quality
QED_3 theory of underdoped high temperature superconductors II: the quantum critical point
We study the effect of gapless quasiparticles in a d-wave superconductor on
the T=0 end point of the Kosterlitz-Thouless transition line in underdoped
high-temperature superconductors. Starting from a lattice model that has
gapless fermions coupled to 3D XY phase fluctuations of the superconducting
order parameter, we propose a continuum field theory to describe the quantum
phase transition between the d-wave superconductor and the spin-density-wave
insulator. Without fermions the theory reduces to the standard Higgs scalar
electrodynamics (HSE), which is known to have the critical point in the
inverted XY universality class. Extending the renormalization group calculation
for the HSE to include the coupling to fermions, we find that the qualitative
effect of fermions is to increase the portion of the space of coupling
constants where the transition is discontinuous. The critical exponents at the
stable fixed point vary continuously with the number of fermion fields , and
we estimate the correlation length exponent (nu = 0.65) and the vortex field
anomalous dimension(eta_Phi=-0.48) at the quantum critical point for the
physical case N=2. The stable critical point in the theory disappears for the
number of Dirac fermions N > N_c, with N_c ~ 3.4 in our approximation. We
discuss the relationship between the superconducting and the chiral (SDW)
transitions, and point to some interesting parallels between our theory and the
Thirring model.Comment: 13 pages including figures in tex
Duality and scaling in 3-dimensional scalar electrodynamics
Three-dimensional scalar electrodynamics, with a local U(1) gauge symmetry,
is believed to be dual to a scalar theory with a global U(1) symmetry, near the
phase transition point. The conjectured duality leads to definite predictions
for the scaling exponents of the gauge theory transition in the type II region,
and allows thus to be scrutinized empirically. We review these predictions, and
carry out numerical lattice Monte Carlo measurements to test them: a number of
exponents, characterising the two phases as well as the transition point, are
found to agree with expectations, supporting the conjecture. We explain why
some others, like the exponent characterising the photon correlation length,
appear to disagree with expectations, unless very large system sizes and the
extreme vicinity of the transition point are considered. Finally, we remark
that in the type I region the duality implies an interesting quantitative
relationship between a magnetic flux tube and a 2-dimensional non-topological
soliton.Comment: 27 pages. v2: reference and minor clarifications added, to appear in
Nucl.Phys.
Monte Carlo simulation of an radio frequency identification system with moving transponders using the partial element equivalent circuit method
Population Pharmacokinetic Modelling of FE 999049, a Recombinant Human Follicle-Stimulating Hormone, in Healthy Women After Single Ascending Doses
OBJECTIVE: The purpose of this analysis was to develop a population pharmacokinetic model for a novel recombinant human follicle-stimulating hormone (FSH) (FE 999049) expressed from a human cell line of foetal retinal origin (PER.C6(®)) developed for controlled ovarian stimulation prior to assisted reproductive technologies.METHODS: Serum FSH levels were measured following a single subcutaneous FE 999049 injection of 37.5, 75, 150, 225 or 450 IU in 27 pituitary-suppressed healthy female subjects participating in this first-in-human single ascending dose trial. Data was analysed by nonlinear mixed effects population pharmacokinetic modelling in NONMEM 7.2.0.RESULTS: A one-compartment model with first-order absorption and elimination rates was found to best describe the data. A transit model was introduced to describe a delay in the absorption process. The apparent clearance (CL/F) and apparent volume of distribution (V/F) estimates were found to increase with body weight. Body weight was included as an allometrically scaled covariate with a power exponent of 0.75 for CL/F and 1 for V/F.CONCLUSIONS: The single-dose pharmacokinetics of FE 999049 were adequately described by a population pharmacokinetic model. The average drug concentration at steady state is expected to be reduced with increasing body weight
Exploring local knowledge and perceptions on zoonoses among pastoralists in northern and eastern Tanzania
Background: Zoonoses account for the most commonly reported emerging and re-emerging infectious diseases in Sub-Saharan Africa. However, there is limited knowledge on how pastoral communities perceive zoonoses in relation to their livelihoods, culture and their wider ecology. This study was carried out to explore local knowledge and perceptions on zoonoses among pastoralists in Tanzania. Methodology and principal findings: This study involved pastoralists in Ngorongoro district in northern Tanzania and Kibaha and Bagamoyo districts in eastern Tanzania. Qualitative methods of focus group discussions, participatory epidemiology and interviews were used. A total of 223 people were involved in the study. Among the pastoralists, there was no specific term in their local language that describes zoonosis. Pastoralists from northern Tanzania possessed a higher understanding on the existence of a number of zoonoses than their eastern districts' counterparts. Understanding of zoonoses could be categorized into two broad groups: a local syndromic framework, whereby specific symptoms of a particular illness in humans concurred with symptoms in animals, and the biomedical framework, where a case definition is supported by diagnostic tests. Some pastoralists understand the possibility of some infections that could cross over to humans from animals but harm from these are generally tolerated and are not considered as threats. A number of social and cultural practices aimed at maintaining specific cultural functions including social cohesion and rites of passage involve animal products, which present zoonotic risk. Conclusions: These findings show how zoonoses are locally understood, and how epidemiology and biomedicine are shaping pastoralists perceptions to zoonoses. Evidence is needed to understand better the true burden and impact of zoonoses in these communities. More studies are needed that seek to clarify the common understanding of zoonoses that could be used to guide effective and locally relevant interventions. Such studies should consider in their approaches the pastoralists' wider social, cultural and economic set up
The SAMPLE Experiment and Weak Nucleon Structure
One of the key elements to understanding the structure of the nucleon is the
role of its quark-antiquark sea in its ground state properties such as charge,
mass, magnetism and spin. In the last decade, parity-violating electron
scattering has emerged as an important tool in this area, because of its
ability to isolate the contribution of strange quark-antiquark pairs to the
nucleon's charge and magnetism. The SAMPLE experiment at the MIT-Bates
Laboratory, which has been focused on s-sbar contributions to the proton's
magnetic moment, was the first of such experiments and its program has recently
been completed. In this paper we give an overview of some of the experimental
aspects of parity-violating electron scattering, briefly review the theoretical
predictions for strange quark form factors, summarize the SAMPLE measurements,
and place them in context with the program of experiments being carried out at
other electron scattering facilities such as Jefferson Laboratory and the Mainz
Microtron.Comment: 61 pages, review articl
Collagen based magnetic nanocomposites for oil removal applications
A stable magnetic nanocomposite of collagen and superparamagnetic iron oxide nanoparticles (SPIONs) is prepared by a simple process utilizing protein wastes from leather industry. Molecular interaction between helical collagen fibers and spherical SPIONs is proven through calorimetric, microscopic and spectroscopic techniques. This nanocomposite exhibited selective oil absorption and magnetic tracking ability, allowing it to be used in oil removal applications. The environmental sustainability of the oil adsorbed nanobiocomposite is also demonstrated here through its conversion into a bi-functional graphitic nanocarbon material via heat treatment. The approach highlights new avenues for converting bio-wastes into useful nanomaterials in scalable and inexpensive ways
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