215 research outputs found
Pion and kaon physics with improved staggered quarks
We compute pseudoscalar meson masses and decay constants using staggered
quarks on lattices with three flavors of sea quarks and lattice spacings
fm and fm. We fit partially quenched results to
``staggered chiral perturbation theory'' formulae, thereby taking into account
the effects of taste-symmetry violations. Chiral logarithms are observed. From
the fits we calculate and , extract Gasser-Leutwyler parameters of
the chiral Lagrangian, and (modulo rather large perturbative errors) find the
light and strange quark masses.Comment: Lattice2003(spectrum); 3 pages, 1 eps figur
Electromagnetic contributions to pseudoscalar masses
We report on the calculation by the MILC Collaboration of the electromagnetic effects on kaon
and pion masses. These masses are computed in QCD with dynamical (asqtad staggered) quarks
plus quenched photons at three lattice spacings varying from 0.12 to 0.06 fm. The masses are fit
to staggered chiral perturbation theory with NLO electromagnetic terms, as well as analytic terms
at higher order. We extrapolate the results to physical light-quark masses and to the continuum
limit. At the current stage of the analysis, most, but not all, of the systematic errors have been
estimated. The main goal is the comparison of kaon electromagnetic splittings to those of the
pion, i.e., an evaluation of the corrections to âDashenâs theorem.â This in turn will allow us to
significantly reduce the systematic errors in our determination of m<sub>u</sub>/m<sub>d</sub>
Leptonic decay constants f_Ds and f_D in three flavor lattice QCD
We determine the leptonic decay constants in three flavor unquenched lattice
QCD. We use O(a^2)-improved staggered light quarks and O(a)-improved charm
quarks in the Fermilab heavy quark formalism. Our preliminary results, based
upon an analysis at a single lattice spacing, are f_Ds = 263(+5-9)(+/-24) MeV
and f_D = 225(+11-13)(+/-21) MeV. In each case, the first reported error is
statistical while the is the combined systematic uncertainty.Comment: Talk presented at Lattice2004(heavy), Fermilab, June 21-26, 2004. 3
pages, 2 figure
Work function changes in the double layered manganite La1.2Sr1.8Mn2O7
We have investigated the behaviour of the work function of La1.2Sr1.8Mn2O7 as
a function of temperature by means of photoemission. We found a decrease of 55
+/- 10 meV in going from 60 K to just above the Curie temperature (125 K) of
the sample. Above T_C the work function appears to be roughly constant. Our
results are exactly opposite to the work function changes calculated from the
double-exchange model by Furukawa, but are consistent with other measurements.
The disagreement with double-exchange can be explained using a general
thermodynamic relation valid for second order transitions and including the
extra processes involved in the manganites besides double-exchange interaction.Comment: 6 pages, 4 figures included in tex
Electromagnetic contributions to pseudoscalar masses
We report on the calculation by the MILC Collaboration of the electromagnetic effects on kaon
and pion masses. These masses are computed in QCD with dynamical (asqtad staggered) quarks
plus quenched photons at three lattice spacings varying from 0.12 to 0.06 fm. The masses are fit
to staggered chiral perturbation theory with NLO electromagnetic terms, as well as analytic terms
at higher order. We extrapolate the results to physical light-quark masses and to the continuum
limit. At the current stage of the analysis, most, but not all, of the systematic errors have been
estimated. The main goal is the comparison of kaon electromagnetic splittings to those of the
pion, i.e., an evaluation of the corrections to âDashenâs theorem.â This in turn will allow us to
significantly reduce the systematic errors in our determination of m<sub>u</sub>/m<sub>d</sub>
Realistic Equations of State for the Primeval Universe
Early universe equations of state including realistic interactions between
constituents are built up. Under certain reasonable assumptions, these
equations are able to generate an inflationary regime prior to the
nucleosynthesis period. The resulting accelerated expansion is intense enough
to solve the flatness and horizon problems. In the cases of curvature parameter
\kappa equal to 0 or +1, the model is able to avoid the initial singularity and
offers a natural explanation for why the universe is in expansion.Comment: 32 pages, 5 figures. Citations added in this version. Accepted EPJ
Prospective longitudinal evaluation of treatment-related toxicity and health-related quality of life during the first year of treatment for pediatric acute lymphoblastic leukemia
Background Pediatric acute lymphoblastic leukemia (ALL) therapy is accompanied by treatment-related toxicities (TRTs) and impaired quality of life. In Australia and New Zealand, children with ALL are treated with either Children's Oncology Group (COG) or international Berlin-Frankfurt-Munster (iBFM) Study Group-based therapy. We conducted a prospective registry study to document symptomatic TRTs (venous thrombosis, neurotoxicity, pancreatitis and bone toxicity), compare TRT outcomes to retrospective TRT data, and measure the impact of TRTs on children's general and cancer-related health-related quality of life (HRQoL) and parents' emotional well-being. Methods Parents of children with newly diagnosed ALL were invited to participate in the ASSET (Acute Lymphoblastic Leukaemia Subtypes and Side Effects from Treatment) study and a prospective, longitudinal HRQoL study. TRTs were reported prospectively and families completed questionnaires for general (Healthy Utility Index Mark 3) and cancer specific (Pediatric Quality of Life Inventory (PedsQL)-Cancer Module) health related quality of life as well the Emotion Thermometer to assess emotional well-being. Results Beginning in 2016, 260 pediatric patients with ALL were enrolled on the TRT registry with a median age at diagnosis of 59âmonths (range 1-213âmonths), 144 males (55.4%), majority with Pre-B cell immunophenotype, nâ=â226 (86.9%), 173 patients (66.5%) treated according to COG platform with relatively equal distribution across risk classification sub-groups. From 2018, 79 families participated in the HRQoL study through the first year of treatment. There were 74 TRT recorded, reflecting a 28.5% risk of developing a TRT. Individual TRT incidence was consistent with previous studies, being 7.7% for symptomatic VTE, 11.9% neurotoxicity, 5.4% bone toxicity and 5.0% pancreatitis. Children's HRQoL was significantly lower than population norms throughout the first year of treatment. An improvement in general HRQoL, measured by the HUI3, contrasted with the lack of improvement in cancer-related HRQoL measured by the PedsQL Cancer Module over the first 12âmonths. There were no persisting differences in the HRQoL impact of COG compared to iBFM therapy. Conclusions It is feasible to prospectively monitor TRT incidence and longitudinal HRQoL impacts during ALL therapy. Early phases of ALL therapy, regardless of treatment platform, result in prolonged reductions in cancer-related HRQoL.Clarissa E. Schilstra, Karen McCleary, Joanna E. Fardell, Mark W. Donoghoe, Emma McCormack, Rishi S. Kotecha, Richard De Abreu Lourenco, Shanti Ramachandran, Ruelleyn Cockcroft, Rachel Conyers, Siobhan Cross, Luciano Dalla, Pozza, Peter Downie, Tamas Revesz, Michael Osborn, Frank Alvaro, Claire E. Wakefield, Glenn M. Marshall, Marion K. Mateos, and Toby N. Trahai
Paleobiology of titanosaurs: reproduction, development, histology, pneumaticity, locomotion and neuroanatomy from the South American fossil record
Fil: GarcĂa, Rodolfo A.. Instituto de InvestigaciĂłn en PaleobiologĂa y GeologĂa. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Salgado, Leonardo. Instituto de InvestigaciĂłn en PaleobiologĂa y GeologĂa. General Roca. RĂo Negro; ArgentinaFil: FernĂĄndez, Mariela. Inibioma-Centro Regional Universitario Bariloche. Bariloche. RĂo Negro; ArgentinaFil: Cerda, Ignacio A.. Instituto de InvestigaciĂłn en PaleobiologĂa y GeologĂa. Museo Provincial Carlos Ameghino. Cipolletti; ArgentinaFil: Carabajal, Ariana Paulina. Museo Carmen Funes. Plaza Huincul. NeuquĂ©n; ArgentinaFil: Otero, Alejandro. Museo de La Plata. Universidad Nacional de La Plata; ArgentinaFil: Coria, Rodolfo A.. Instituto de PaleobiologĂa y GeologĂa. Universidad Nacional de RĂo Negro. NeuquĂ©n; ArgentinaFil: Fiorelli, Lucas E.. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica. Anillaco. La Rioja; Argentin
The Physics of Star Cluster Formation and Evolution
© 2020 Springer-Verlag. The final publication is available at Springer via https://doi.org/10.1007/s11214-020-00689-4.Star clusters form in dense, hierarchically collapsing gas clouds. Bulk kinetic energy is transformed to turbulence with stars forming from cores fed by filaments. In the most compact regions, stellar feedback is least effective in removing the gas and stars may form very efficiently. These are also the regions where, in high-mass clusters, ejecta from some kind of high-mass stars are effectively captured during the formation phase of some of the low mass stars and effectively channeled into the latter to form multiple populations. Star formation epochs in star clusters are generally set by gas flows that determine the abundance of gas in the cluster. We argue that there is likely only one star formation epoch after which clusters remain essentially clear of gas by cluster winds. Collisional dynamics is important in this phase leading to core collapse, expansion and eventual dispersion of every cluster. We review recent developments in the field with a focus on theoretical work.Peer reviewe
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