662 research outputs found
Thermal Model Analysis of Particle Ratios at GSI Ni-Ni Experiments Using Exact Strangeness Conservation
The production of hadrons in Ni-Ni at the GSI is considered in a hadronic gas
model with chemical equilibrium. Special attention is given to the abundance of
strange particles which are treated using the exact conservation of
strangeness. It is found that all the data can be described using a temperature
T = 70 pm 10 MeV and a baryon chemical potential mu_B = 720 pm 20 MeV.Comment: Revtex, 7 pages, 3 figures in postscript forma
Dynamics of polymer ejection from capsid
Polymer ejection from a capsid through a nanoscale pore is an important
biological process with relevance to modern biotechnology. Here, we study
generic capsid ejection using Langevin dynamics. We show that even when the
ejection takes place within the drift-dominated region there is a very high
probability for the ejection process not to be completed. Introducing a small
aligning force at the pore entrance enhances ejection dramatically. Such a pore
asymmetry is a candidate for a mechanism by which a viral ejection is
completed. By detailed high-resolution simulations we show that such capsid
ejection is an out-of-equilibrium process that shares many common features with
the much studied driven polymer translocation through a pore in a wall or a
membrane. We find that the escape times scale with polymer length, . We show that for the pore without the asymmetry the previous
predictions corroborated by Monte Carlo simulations do not hold. For the pore
with the asymmetry the scaling exponent varies with the initial monomer density
(monomers per capsid volume) inside the capsid. For very low densities
the polymer is only weakly confined by the capsid, and we
measure , which is close to obtained for polymer
translocation. At intermediate densities the scaling exponents
and for and , respectively. These scalings are in
accord with a crude derivation for the lower limit . For the
asymmetrical pore precise scaling breaks down, when the density exceeds the
value for complete confinement by the capsid, . The
high-resolution data show that the capsid ejection for both pores, analogously
to polymer translocation, can be characterized as a multiplicative stochastic
process that is dominated by small-scale transitions.Comment: 10 pages, 6 figure
Extended shell-model calculation for even N=82 isotones with realistic effective interactions
The shell model within the shell is applied to
calculate nuclear structure properties of the even Z=52 - 62, N=82 isotones.
The results are compared with experimental data and with the results of a
quasiparticle random-phase approximation (QRPA) calculation. The interaction
used in these calculations is a realistic two-body G-matrix interaction derived
from modern meson-exchange potential models for the nucleon-nucleon
interaction. For the shell model all the two-body matrix elements are
renormalized by the -box method whereas for the QRPA the effective
interaction is defined by the G-matrix.Comment: 25 pages, Elsevier latex style. Submitted to Nuclear Physics
Study of odd-mass N=82 isotones with realistic effective interactions
The microscopic quasiparticle-phonon model, MQPM, is used to study the energy
spectra of the odd , N=82 isotones. The results are compared with
experimental data, with the extreme quasiparticle-phonon limit and with the
results of an unrestricted shell model (SM)
calculation. The interaction used in these calculations is a realistic two-body
G-matrix interaction derived from modern meson-exchange potential models for
the nucleon-nucleon interaction. For the shell model all the two-body matrix
elements are renormalized by the -box method whereas for the MQPM the
effective interaction is defined by the G-matrix.Comment: Elsevier latex style espart, 26 pages, submitted to Nuclear Physics
Vertaissuhteiden vaikutukset kouluviihtyvyyteen
TiivistelmÀ. TÀssÀ kandidaatin tutkielmassa tutkin vertaissuhteiden vaikutuksia kouluviihtyvyyteen. Tutkielma on toteutettu kuvailevana kirjallisuuskatsauksena.
Kouluviihtyvyys on olennainen ja erottamaton osa koulua, kuten myös vertaissuhteet. Suomalaiset lapset eivÀt jostain syystÀ viihdy koulussa kovinkaan hyvin. Koska koulun ulkopuoliset hyvinvointiolosuhteet ovat Suomessa korkeat, tÀytyy selitysten löytyÀ koulussa tapahtuvista asioista.
Kouluviihtyvyys on abstrakti ja moniulotteinen kÀsite, mutta yksinkertaisesti sitÀ voidaan kutsua oppilaan kÀsitykseksi hÀnen omasta kouluelÀmÀn laadusta ja koulukokemusten positiivisuudesta. Kouluviihtyvyyteen vaikuttavia tekijöitÀ on paljon, ja ne muodostavat yhdessÀ kokonaisuuden, joka vaikuttaa yksilön kouluviihtyvyyteen.
Vertaiset ovat yleensÀ samanikÀisiÀ lapsia, jotka ovat samalla kehitystasolla. Koulussa vertaisryhmiÀ ja -suhteita syntyy itsestÀÀn. YstÀvyys- ja kaverisuhteet ovat yleisiÀ vertaissuhteita. Vertaissuhteisiin voi kuitenkin liittyÀ myös ongelmia, kuten esimerkiksi kiusaamista. Vertaissuhteet ovat keskeisessÀ asemassa laajemmasta kouluilmapiiristÀ puhuessa, joskin siihen linkittyy myös muita tekijöitÀ.
Kirjallisuuskatsauksen tulokset osoittavat, ettÀ vertaissuhteilla on suora vaikutus kouluviihtyvyyteen. Positiiviset vertaissuhteet nostavat kouluviihtyvyyttÀ, kun taas negatiiviset vaikuttavat siihen laskevasti. YstÀvÀt tekevÀt koulupÀivistÀ mukavampia ja tuovat oppilaille iloa. Positiiviset vertaissuhteet voivat myös toimia suojaavina tekijöinÀ muita kouluviihtyvyyttÀ laskevia tekijöitÀ vastaan
Nuclear Structure Aspects of the Neutrinoless Double Beta Decay
In this article, we analyze some nuclear structure aspects of the
neutrinoless double beta decay nuclear matrix elements (NME), in the framework
of the Interacting Shell Model. We give results for the decays of 48Ca, 76Ge,
82Se, 124Sn, 128Te, 130Te, and 136Xe, using improved effective interactions and
valence spaces. We examine the dependence of the NME's on the effective
interaction and the valence space, and analyze the effects of the short range
correlations and the finite size of the nucleon. Finally we study the influence
of the deformation on the values of the NME's.Comment: To appear in EJP-
The effect of microstructure on mechanical properties of HVOF sprayed WC-CoCr composite coatings
This study aims for deeper understanding of the composition and phase changes occurring during HVOF spraying of the powder to WC-CoCr coatings. Also, the effect of lamellar microstructure on the mechanical properties is studied. Compositional and microstructural features are studied by means of X-ray diffraction, XRF, FE-SEM and TEM (EDX, EELS). Mechanical properties are mainly studied by different instrumented indentation and nanoindentation techniques. The use of two new fracture parameters, complementing the fracture toughness value of the coating, are proposed and examined. Higher load range indentations are used to measure cross-sectional and surface hardness, elastic modulus and fracture toughness of the coatings. Mechanical properties of individual phases are studied by nanoindentation. To our knowledge this is the first time that the mechanical properties of this amorphous/nanocrystalline matrix are studied. ICP (In-situ Coating Property) sensor, developed for quality control and residual stress evaluation, is also used to measure the elastic modulus and coefficient of thermal expansion (CTE) of the coatings. Abrasion wear resistance of the coatings are studied according to standard ASTM G 65D.
Because of the brittle nature of HVOF coatings, the main focus of this study is in the effects of coating microstructure on fracture toughness, and on crack initiation and propagation resistance. It is shown that even when two similar coatings have equal indentation fracture toughness values, the critical crack initiation loads may be very different. This new parameter is expected to be extremely useful in the evaluation of the coating performance under loading conditions
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