824 research outputs found
Thermal photons from fluctuating initial conditions
Event-by-event fluctuations of initial QCD-matter density produced in
heavy-ion collisions at RHIC enhance the production of thermal photons
significantly in the region GeV/ compared to a smooth
initial-state averaged profile in the ideal hydrodynamic calculation. This
enhancement is a an early time effect due to the presence of hotspots or
over-dense regions in the fluctuating initial state. The effect of fluctuations
is found to be stronger in peripheral than in central collisions.Comment: 4 pages, 3 figures. Talk given at Quark Matter 2011, 22-28 May 2011,
Annecy, Franc
Systematics of parton-medium interaction from RHIC to LHC
Despite a wealth of experimental data for high-P_T processes in heavy-ion
collisions, discriminating between different models of hard parton-medium
interactions has been difficult. A key reason is that the pQCD parton spectrum
at RHIC is falling so steeply that distinguishing even a moderate shift in
parton energy from complete parton absorption is essentially impossible. In
essence, energy loss models are effectively only probed in the vicinity of zero
energy loss and, as a result, at RHIC energies only the pathlength dependence
of energy loss offers some discriminating power. At LHC however, this is no
longer the case: Due to the much flatter shape of the parton p_T spectra
originating from 2.76 AGeV collisions, the available data probe much deeper
into the model dynamics. A simultaneous fit of the nuclear suppression at both
RHIC and LHC energies thus has great potential for discriminating between
various models that yield equally good descriptions of RHIC data alone.Comment: Talk given at Quark Matter 2011, 22-28 May 2011, Annecy, Franc
Elliptic flow from event-by-event hydrodynamics
We present an event-by-event hydrodynamical framework which takes into
account the initial density fluctuations arising from a Monte Carlo Glauber
model. The elliptic flow is calculated with the event plane method and a
one-to-one comparison with the measured event plane is made. Both the
centrality- and -dependence of the are remarkably well reproduced.
We also find that the participant plane is a quite good approximation for the
event plane.Comment: 4 pages, 3 figures. Talk given at Quark Matter 2011, 22-28 May 2011,
Annecy, Franc
Simple Electromagnetic Motor Model for Torsional Analysis of Variable Speed Drives with an Induction Motor
Torsional vibrations must be considered in the design of all high-power drive-trains including an induction motor. Electromagnetic (EM) field in the air gap of an induction motor generates additional magnetic stiffness and damping between the rotor and stator. The inclusion of these magnetic effects is limited by the availability of simple and portable motor models. The main aim of this paper is to introduce a motor model including the speed and torque variation. The presented model is based on the linearization of the common space-vector models of induction motors. The parameters of this model are identified for the rated operating condition. This motor model can be extended to include variable speed and torque operation. The numerical results demonstrate that this model describes accurately the magnetic effects over the large speed and torque range. In addition, the numerical results demonstrate the significance of magnetic stiffness and damping in variable speed motor-driven compressors with a soft coupling
Molecular characterisation of infectious pancreatic necrosis viruses isolated from farmed fish in Finland
Abstract Infectious pancreatic necrosis virus (IPNV) has been isolated annually since 1987 from salmonids without clinical signs at coastal fish farms in Finland. In the inland area, viral isolations were rare until 2012, when IPNV was
detected at several freshwater fish farms. Between 2013 and 2015, the infection spread and IPNV was continuously isolated from several farms, both inland and on the coast. The aim of this study was to genetically characterise the IPNV isolates collected from Finnish coastal and inland fish farms over the last 15 years, and to detect genetic changes that may have occurred in the virus populations during the study period. The partial VP2 gene sequence from 88 isolates was analysed. In addition, a complete genomic coding sequence was obtained from 11 isolates. Based on the genetic analyses, Finnish IPNV isolates belong to three genogroups: 2, 5 and 6. The genetic properties of the isolates appear to vary between inland farms producing juveniles and food fish farms in the coastal region: the inland farms harboured genogroup 2 isolates, whereas at coastal farms, all three genogroups were detected. Little genetic variation was observed within the Finnish genogroup 2 and 5 isolates, whereas among the genogroup 6 isolates, two subgroups were detected. All isolates studied demonstrated amino acid patterns in the viral VP2 gene previously associated with avirulence. However, increased mortality was detected at some of the farms, indicating that more research is needed to clarify the relationship between the pathogenicity and genetic properties of IPNV isolates from different genogroups
Aivotoiminnan häiriöiden yhteydessä yleisesti koetut psykososiaaliset vaikeudet : PARADISE24-kyselyn tutkimusperusta
Ihmisen kokonaistilanne on tärkeä ottaa hoidossa ja kuntoutuksessa huomioon. Psychosocial Factors Relevant to Brain Disorders in Europa (PARADISE) -hanke toteutettiin kymmenen instituutin yhteistyössä professori Ciezan johdolla 2010–2013. Tavoitteena oli kehittää tutkimukseen perustuva menetelmä, jonka avulla voidaan kartoittaa psykososiaalisia vaikeuksia eri aivotoiminnan häiriöiden hoidossa, kuntoutuksessa ja tutkimisessa. Hankkeessa oli lähtökohtana oletus psykososiaalisten vaikeuksien horisontaalisesta epidemiologiasta. Hankkeessa tutkittiin yhdeksää aivotoiminnan häiriötä: dementiaa, depressiota, epilepsiaa, migreeniä, MS-tautia, Parkinsonin tautia, skitsofreniaa, aivoverenkiertohäiriötä ja päihderiippuvuutta. Kunkin häiriön osalta toteutettiin systemaattinen kirjallisuuskatsaus ja fokusryhmähaastattelu. Esiin nousseet psykososiaaliset vaikeudet luokiteltiin ja linkitettiin kansainväliseen toimintakykyluokitukseen (ICF). Eri häiriöille yhteisten 64 psykososiaalisen vaikeuden yleisyyttä ja intensiteettiä tutkittiin yksilöhaastatteluissa (n = 722). Tulosten pohjalta muodostettiin yleisiä psykososiaalisia vaikeuksia mahdollisimman laajasti kattava PARADISE24-kysely. Oletus eri häiriöiden yhteisistä psykososiaalisista ongelmista osoittautui todeksi. Kyselyyn valikoitui neljätoista kysymystä ICF:n osa-alueelta b Ruumiin/kehon toiminnot ja kymmenen kysymystä osa-alueelta d Suoritukset ja osallistuminen. Psykososiaalisten vaikeuksien intensiteetissä esiintyi kuitenkin häiriöiden välillä eroja siten, että psykiatristen tai päihdehäiriöiden takia haastatellut käyttivät laaja-alaisesti viisiportaista vastausvaihtoehtojen asteikkoa, mutta neurologisten häiriöiden yhteydessä kaksi- tai kolmeportainen asteikko vaikutti riittävältä. PARADISE24-kysely sisältää olennaiset kysymykset, mutta jatkotutkimusta tarvitaan erityisesti kyselyn toimivuudesta seurantakäytössä. Raportissa esitetään PARADISE24-kyselyn valmistamisen tutkimusperusta horisontaalisten tulosten sekä erikseen päihdehäiriöiden näkökulmasta.36,00 euro
Dynamical freeze-out in event-by-event hydrodynamics
In hydrodynamical modeling of the ultrarelativistic heavy-ion collisions the
freeze-out is typically performed at a constant temperature or density. In this
work we apply a dynamical freeze-out criterion, which compares the
hydrodynamical expansion rate with the pion scattering rate. Recently many
calculations have been done using event-by-event hydrodynamics where the
initial density profile fluctuates from event to event. In these event-by-event
calculations the expansion rate fluctuates strongly as well, and thus it is
interesting to check how the dynamical freeze-out changes hadron distributions
with respect to the constant temperature freeze-out. We present hadron spectra
and elliptic flow calculated using (2+1)-dimensional ideal hydrodynamics, and
show the differences between constant temperature and dynamical freeze-out
criteria. We find that the differences caused by different freeze-out criteria
are small in all studied cases.Comment: 8 pages, 11 figures, to be published in the proceedings of the 28th
Winter Workshop on Nuclear Dynamics, Puerto Rico, April 7-14, 201
Clustered Single Cellulosic Fiber Dissolution Kinetics and Mechanisms through Optical Microscopy under Limited Dissolving Conditions
Herein, we describe a new method of assessing the kinetics of dissolution of single fibers by dissolution under limited dissolving conditions. The dissolution is followed by optical microscopy under limited dissolving conditions. Videos of the dissolution were processed in Image) to yield kinetics for dissolution, based on the disappearance of pixels associated with intact fibers. Data processing was performed using the Python language, utilizing available scientific libraries. The methods of processing the data include clustering of the single fiber data, identifying clusters associated with different fiber types, producing average dissolution traces and also extraction of practical parameters, such as, time taken to dissolve 25, SO, 75, 95, and 99.5% of the clustered fibers. In addition to these simple parameters, exponential fitting was also performed yielding rate constants for fiber dissolution. Fits for sample and cluster averages were variable, although demonstrating first-order kinetics for dissolution overall. To illustrate this process, two reference pulps (a bleached softwood kraft pulp and a bleached hardwood pre hydrolysis kraft pulp) and their cellulase-treated versions were analyzed. As expected, differences in the kinetics and dissolution mechanisms between these samples were observed. Our initial interpretations are presented, based on the combined mechanistic observations and single fiber dissolution kinetics for these different samples. While the dissolution mechanisms observed were similar to those published previously, the more direct link of mechanistic information with the kinetics improve our understanding of cell wall structure and pre-treatments, toward improved processability.Peer reviewe
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