2,939 research outputs found
Study of the Flux and Spectral Variations in the VHE Emission from the Blazar Markarian 501, with the MAGIC Telescope
The blazar Markarian 501 (Mrk 501) was observed above 100 GeV with the MAGIC
Telescope during May, June and July 2005. The high sensitivity of the
instrument made possible the detection of the source with high significance in
each of the observing nights. During this observational campaign, the emitted
gamma-ray flux from Mkn 501 was found to vary by one order of magnitude, and
showed a high correlation with spectral changes. Intra-night flux variability
was also observed, with flux-doubling times of ~2 minutes. The data showed a
clear evidence of a spectral peak (in the nuFnu representation) during the
nights when the gamma-ray activity was highest. The location of this spectral
feature was found to be correlated with the emitted gamma-ray flux. In these
proceedings we discuss some of the results of this unprecedented spectral and
temporal analysis of Mrk 501 observations in the very high energy range.Comment: 4 pages, 3 figures, manuscript submitted on behalf of the MAGIC
collaboration to the First GLAST Symposium (oral presentation
Summary of the COSY-11 Measurements of Hyperon Production
The studies of hyperon production performed at COSY-11 are summarized. The
results of the experiments in the reaction channels pp-->pK+Lambda,
pp-->pK+Sigma0, and pp-->nK+Sigma+ are shown. Excitation functions
fromthreshold up to about 90MeV excess energies have been evaluated with high
precision for the Lambda and Sigma0 production. The Lambdap and Sigma0p final
state interactions were extracted. The Sigma+ production was measured at 13 and
60 MeV excess energies.Comment: 8 pages, 4 figures, Talk given at Symposium on Meson Physics at
COSY-11 and WASA-at-COSY, Cracow, Poland, 17-22 Jun 200
Brain matters…in social sciences
Here we offer a general introduction to cognitive neuroscience and provide examples relevant to psychology, healthcare and bioethics, law and criminology, information studies, of how brain studies have influenced, are influencing or show the potential to influence the social sciences. We argue that social scientists should read, and be enabled to understand, primary sources of evidence in cognitive neuroscience. We encourage cognitive neuroscientists to reflect upon the resonance that their work may have across the social sciences and to facilitate a mutually enriching interdisciplinary dialogue
Pseudo-critical clusterization in nuclear multifragmentation
In this contribution we show that the biggest fragment charge distribution in
central collisions of Xe+Sn leading to multifragmentation is an admixture of
two asymptotic distributions observed for the lowest and highest bombarding
energies. The evolution of the relative weights of the two components with
bombarding energy is shown to be analogous to that observed as a function of
time for the largest cluster produced in irreversible aggregation for a finite
system. We infer that the size distribution of the largest fragment in nuclear
multifragmentation is also characteristic of the time scale of the process,
which is largely determined by the onset of radial expansion in this energy
range.Comment: 4 pages, 3 figures, Contribution to conference proceedings of the
25th International Nuclear Physics Conference (INPC 2013
Leading isospin-breaking corrections to pion, kaon and charmed-meson masses with Twisted-Mass fermions
We present a lattice computation of the isospin-breaking corrections to
pseudoscalar meson masses using the gauge configurations produced by the
European Twisted Mass collaboration with dynamical quarks at
three values of the lattice spacing ( and fm)
with pion masses in the range MeV. The strange and
charm quark masses are tuned at their physical values. We adopt the RM123
method based on the combined expansion of the path integral in powers of the
- and -quark mass difference () and of the
electromagnetic coupling . Within the quenched QED approximation,
which neglects the effects of the sea-quark charges, and after the
extrapolations to the physical pion mass and to the continuum and infinite
volume limits, we provide results for the pion, kaon and (for the first time)
charmed-meson mass splittings, for the prescription-dependent parameters
, \epsilon_\gamma(\overline{MS}, 2~\mbox{GeV}),
\epsilon_{K^0}(\overline{MS}, 2~\mbox{GeV}), related to the violations of the
Dashen's theorem, and for the light quark mass difference (\widehat{m}_d -
\widehat{m}_u)(\overline{MS}, 2~\mbox{GeV}).Comment: 47 pages, 20 figures, 4 tables; comments on QED and QCD splitting
prescriptions added; version to appear in PR
Iso-vector and Iso-scalar Tensor Charges of the Nucleon from Lattice QCD
We present results for the iso-vector and flavor diagonal tensor charges
, , , and needed to probe novel tensor
interactions at the TeV scale in neutron and nuclear -decays and the
contribution of the quark electric dipole moment (EDM) to the neutron EDM. The
lattice QCD calculations were done using nine ensembles of gauge configurations
generated by the MILC collaboration using the HISQ action with 2+1+1 dynamical
flavors. These ensembles span three lattice spacings and
fm and three quark masses corresponding to the pion masses and MeV. Using estimates from these ensembles, we
quantify all systematic uncertainties and perform a simultaneous extrapolation
in the lattice spacing, volume and light quark masses for the connected
contributions. The final estimates of the connected nucleon (proton) tensor
charge for the iso-vector combination is in the
scheme at GeV. The additional disconnected quark loop
contributions needed for the flavor-diagonal matrix elements are calculated
using a stochastic estimator employing the truncated solver method with the
all-mode-averaging technique. We find that the size of the disconnected
contribution is smaller than the statistical error in the connected
contribution. This allows us to bound the disconnected contribution and include
it as an additional uncertainty in the flavor-diagonal charges. After a
continuum extrapolation, we find , and . The strangeness tensor charge, that can make a
significant contribution to the neutron EDM due to the large ratio
, is in the continuum limit.Comment: Final published versio
Evaluation of Overall Survival (OS) and Event-Free Survival (EFS) of paediatric sarcoma patients at a single institution
Aims: To evaluate OS and EFS of paediatric sarcoma patients with an interest in comparing metastatic cases with non-metastatic cases, and compiling statistics on treatment methods.
Methods: Information was obtained from patient notes in the Schiehallion ward. These contained information about diagnosis, treatment, prognostic indicators, and outcomes for each patient.
Results: 56 patients, 2001-2008. Osteosarcoma: 11 patients, 7♂, 4♀; age range: 4-16; = 10; OS = 64%, EFS = 55%; Primary site of disease: Femur (47%), Tibia (41%), Humerus (5.5%), Scapula (5.5%), Other (1%); Metastatic Rate = 27% (OS = 0%). Ewing’s sarcoma: 24 patients, 10♂, 14♀; age range: 1-16, = 12; OS = 71%, EFS = 58%; Primary site of disease: Pelvis (29%), Femur (22%), Paraspinal (16%), Chest Wall (10%), Tibia (10%), Other (13%); Metastatic Rate = 21% (OS = 40%; EFS = 40%); Alveolar rhabdomyosarcoma: 10 patients; OS= 80%, EFS = 60%; Metastatic Rate = 20% (OS = 100%; EFS = 100%). Embryonal rhabdomyosarcoma: 11 patients; OS = 73%, EFS = 73%; Metastatic Rate = 0%.
Conclusions: Our results reflect access to an experienced and innovative paediatric sarcoma service with close links to a national Sarcoma MDT. The data falls in line with other studies in terms of age of onset, location of primary tumour, metastatic rate, site of metastases, and prognosis for all cancer types. Limb salvage surgery is greatly favoured over amputation for both osteosarcoma and Ewing’s sarcoma. Females have a more favourable prognosis in osteosarcoma and a slightly poorer prognosis in Ewing’s sarcoma. Yorkhill’s overall survival rates are currently better than the UK-wide statistic for three of the four tumours examined.</p
matrix elements of the chromomagnetic operator on the lattice
We present the results of the first lattice QCD calculation of the matrix elements of the chromomagnetic operator , which appears in the effective Hamiltonian
describing transitions in and beyond the Standard Model. Having
dimension 5, the chromomagnetic operator is characterized by a rich pattern of
mixing with operators of equal and lower dimensionality. The multiplicative
renormalization factor as well as the mixing coefficients with the operators of
equal dimension have been computed at one loop in perturbation theory. The
power divergent coefficients controlling the mixing with operators of lower
dimension have been determined non-perturbatively, by imposing suitable
subtraction conditions. The numerical simulations have been carried out using
the gauge field configurations produced by the European Twisted Mass
Collaboration with dynamical quarks at three values of the
lattice spacing. Our result for the B-parameter of the chromomagnetic operator
at the physical pion and kaon point is , while
in the SU(3) chiral limit we obtain . Our findings are
significantly smaller than the model-dependent estimate ,
currently used in phenomenological analyses, and improve the uncertainty on
this important phenomenological quantity.Comment: 20 pages, 4 figures, 2 table. Refined SU(3) ChPT analysis with no
changes in the final result. Version to appear in PR
- …