8,268 research outputs found
Creating a high-resolution picture of Cygnus with the Cherenkov Telescope Array
The Cygnus region hosts one of the most remarkable star-forming regions in
the Milky Way. Indeed, the total mass in molecular gas of the Cygnus X complex
exceeds 10 times the total mass of all other nearby star-forming regions.
Surveys at all wavelengths, from radio to gamma-rays, reveal that Cygnus
contains such a wealth and variety of sources---supernova remnants (SNRs),
pulsars, pulsar wind nebulae (PWNe), H II regions, Wolf-Rayet binaries, OB
associations, microquasars, dense molecular clouds and superbubbles---as to
practically be a galaxy in microcosm. The gamma-ray observations along reveal a
wealth of intriguing sources at energies between 1 GeV and tens of TeV.
However, a complete understanding of the physical phenomena producing this
gamma-ray emission first requires us to disentangle overlapping sources and
reconcile discordant pictures at different energies. This task is made more
challenging by the limited angular resolution of instruments such as the Fermi
Large Area Telescope, ARGO-YBJ, and HAWC and the limited sensitivity and field
of view of current imaging atmospheric Cherenkov telescopes (IACTs). The
Cherenkov Telescope Array (CTA), with its improved angular resolution, large
field of view, and order of magnitude gain in sensitivity over current IACTs,
has the potential to finally create a coherent and well-resolved picture of the
Cygnus region between a few tens of GeV and a hundred TeV. We describe a
proposed strategy to study the Cygnus region using CTA data, which combines a
survey of the whole region at and with deeper observations of two sub-regions that host rich
groups of known gamma-ray sources.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
On q-Gaussians and Exchangeability
The q-Gaussians are discussed from the point of view of variance mixtures of
normals and exchangeability. For each q< 3, there is a q-Gaussian distribution
that maximizes the Tsallis entropy under suitable constraints. This paper shows
that q-Gaussian random variables can be represented as variance mixtures of
normals. These variance mixtures of normals are the attractors in central limit
theorems for sequences of exchangeable random variables; thereby, providing a
possible model that has been extensively studied in probability theory. The
formulation provided has the additional advantage of yielding process versions
which are naturally q-Brownian motions. Explicit mixing distributions for
q-Gaussians should facilitate applications to areas such as option pricing. The
model might provide insight into the study of superstatistics.Comment: 14 page
Restricted random walk model as a new testing ground for the applicability of q-statistics
We present exact results obtained from Master Equations for the probability
function P(y,T) of sums of the positions x_t of a discrete
random walker restricted to the set of integers between -L and L. We study the
asymptotic properties for large values of L and T. For a set of position
dependent transition probabilities the functional form of P(y,T) is with very
high precision represented by q-Gaussians when T assumes a certain value
. The domain of y values for which the q-Gaussian apply
diverges with L. The fit to a q-Gaussian remains of very high quality even when
the exponent of the transition probability g(x)=|x/L|^a+p with 0<p<<1 is
different from 1, all though weak, but essential, deviation from the q-Gaussian
does occur for . To assess the role of correlations we compare the T
dependence of P(y,T) for the restricted random walker case with the equivalent
dependence for a sum y of uncorrelated variables x each distributed according
to 1/g(x).Comment: 5 pages, 7 figs, EPL (2011), in pres
On MSSM charged Higgs boson production in association with an electroweak W boson at electron positron colliders
We present a calculation of the cross section for the process e+ e- --> W+/-
H-/+ in the minimal supersymmetric standard model (MSSM) and the Two Higgs
Doublet Model (THDM). We study the basic features of the MSSM prediction for
some distinctive parameter scenarios. We find large effects from virtual
squarks for scenarios with large mixing in the stop sector which can lead to a
cross section vastly different from a THDM with identical Higgs sector
parameters. We investigate this interesting behaviour in more detail by
thoroughly scanning the MSSM parameter space for regions of large cross
section. For a charged Higgs boson too heavy to be pair-produced at such a
machine, it turns out that a large MSSM cross section with a good chance of
observation is linked to a squark mass scale below 600 GeV and a considerable
amount of mixing in either the stop and sbottom sector.Comment: 25 pages, 10 figures (two in colour). Substantially improved on the
MSSM parameter restrictions taken into account. Added some reference
Kit receptor tyrosine kinase dysregulations in feline splenic mast cell tumours
This study investigated Ki t receptor dysregulations (cytoplasmic immunohistochemical expression
and/or c-KIT mutations) in cats a\ufb00ected with splenic mast cell tumours. Twenty-two cats were
included. Median survival time was 780 days (range: 1\u20131219). An exclusive splenic involvement was
signi\ufb01cantly (P = 0.042) associated with longer survival (807 versus 120 days). Eighteen tumours
(85.7%) showed Kit cytoplasmic expression (Kit pattern 2, 3). Mutation analysis was successful in 20
cases. Fourteen missense mutations were detected in 13 out of 20 tumours (65%). Eleven (78.6%)
were located in exon 8, and three (21.6%) in exon 9. No mutations were detected in exons 11 and 17.
Seven mutations corresponded to the same internal tandem duplication in exon 8 (c.1245_1256dup).
Although the association between Kit cytoplasmic expression and mutations was signi\ufb01cant,
immunohistochemistry cannot be considered a surrogate marker for mutation analysis. No
correlation was observed between c-Kit mutations and tumour di\ufb00erentiation, mitotic activity or
survival
Coronal-line forest active galactic nuclei I. Physical properties of the emission-line regions
Coronal-line forest (CLiF) active galactic nuclei (AGNs) are characterized by strong high-ionization lines, which contrasts with what is found in most AGNs. Here, we carry out a multiwavelength analysis aimed at understanding the physical processes in the narrow-line region (NLR) of these objects, and at discovering whether they are indeed a special class of AGNs. By comparing coronal emission-line ratios we conclude that there are no differences between CLiF and non-CLiF AGNs. We derive physical conditions of the NLR gas and we find electron densities in the range of 3.6 Ă 102 to 1.7 Ă 104 cmâ3 and temperatures of 3.7 Ă 103 to 6.3 Ă 104 K, suggesting that the ionization mechanism is associated primarily with photoionization by the AGN. We suggest an NLR dominated by matter-bounded clouds to explain the high-ionization line spectrum observed. The mass of the central black hole, derived from the stellar velocity dispersion, shows that most of the objects have values in the interval 107â108 Mâ. Our results imply that CLiF AGNs are not in a separate category of AGNs. In all optical/near-infrared emission-line properties analysed, they represent an extension to the low/high ends of the distribution within the AGN class
Creating a high-resolution picture of Cygnus with the Cherenkov Telescope Array
The Cygnus region hosts one of the most remarkable star-forming regions in
the Milky Way. Indeed, the total mass in molecular gas of the Cygnus X complex
exceeds 10 times the total mass of all other nearby star-forming regions.
Surveys at all wavelengths, from radio to gamma-rays, reveal that Cygnus
contains such a wealth and variety of sources---supernova remnants (SNRs),
pulsars, pulsar wind nebulae (PWNe), H II regions, Wolf-Rayet binaries, OB
associations, microquasars, dense molecular clouds and superbubbles---as to
practically be a galaxy in microcosm. The gamma-ray observations along reveal a
wealth of intriguing sources at energies between 1 GeV and tens of TeV.
However, a complete understanding of the physical phenomena producing this
gamma-ray emission first requires us to disentangle overlapping sources and
reconcile discordant pictures at different energies. This task is made more
challenging by the limited angular resolution of instruments such as the Fermi
Large Area Telescope, ARGO-YBJ, and HAWC and the limited sensitivity and field
of view of current imaging atmospheric Cherenkov telescopes (IACTs). The
Cherenkov Telescope Array (CTA), with its improved angular resolution, large
field of view, and order of magnitude gain in sensitivity over current IACTs,
has the potential to finally create a coherent and well-resolved picture of the
Cygnus region between a few tens of GeV and a hundred TeV. We describe a
proposed strategy to study the Cygnus region using CTA data, which combines a
survey of the whole region at and with deeper observations of two sub-regions that host rich
groups of known gamma-ray sources
High Dose Chemotherapy and Autologous Stem Cell Transplantation in Non-Hodgkin's Lymphoma: an Eight-Year Experience
Autologous stem cell transplantation (ASCT) is commonly used in relapsed or refractory non-Hodgkin's lymphoma (NHL). Several trials report the role of ASCT for high risk patients. We evaluated the results and the prognostic factors influencing the therapeutic effects on the patients who were treated with high dose chemotherapy (HDC) and autologous peripheral stem cell transplantation. We analyzed the data of 40 cases with NHL who underwent ASCT after HDC. Twenty-four patients had high-risk disease, 12 cases sensitive relapse, and two cases resistant relapse or primary refractory each. The median age of patients was 34 years (range, 14-58 years). The median follow-up duration from transplantation was 16 months (range, 0.6-94 months). Estimated overall survival and progression-free survival at 5 years were 40% and 30%, respectively. Poor prognostic factors for survival included older age (â„ 45 years), poor performance status in all patient analysis, and a longer interval between first complete remission and transplantation in high risk patients. In high risk NHL patients, transplantation should be done early after first complete remission to overcome chemo-resistance
High sensitivity measurement of 224Ra and 226Ra in water with an improved hydrous titanium oxide technique at the Sudbury Neutrino Observatory
The existing hydrous titanium oxide (HTiO) technique for the measurement of
224Ra and 226Ra in the water at the Sudbury Neutrino Observatory (SNO) has been
changed to make it faster and less sensitive to trace impurities in the HTiO
eluate. Using HTiO-loaded filters followed by cation exchange adsorption and
HTiO co-precipitation, Ra isotopes from 200-450 tonnes of heavy water can be
extracted and concentrated into a single sample of a few millilitres with a
total chemical efficiency of 50%. Combined with beta-alpha coincidence
counting, this method is capable of measuring 2.0x10^3 uBq/kg of 224Ra and
3.7x10^3 uBq/kg of 226Ra from the 232Th and 238U decay chains, respectively,
for a 275 tonne D2O assay, which are equivalent to 5x10^16 g Th/g and 3x10^16 g
U/g in heavy water.Comment: 8 Pages, 2 figures and 2 table
State Immigrant Rights Highlights 2021: Advancing Community Health and Well-Being
This report highlights the immigrant inclusive laws enacted in 2021, as well as some pending bills and campaigns. During this time, states adopted policies improving access to health care, higher education, and professional licenses for immigrants; protecting the rights of workers and tenants; investing in access to counsel; strengthening driver and consumer privacy; and limiting local entanglement in federal immigration enforcement efforts.As Congress considers options for providing a pathway to permanent status or temporary relief to millions of immigrants in the U.S., states and localities have taken significant action to improve the lives of their community members, regardless of their immigration status. In response to effective local organizing, almost half the states adopted immigrant-inclusive laws and policies in 2021
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