8,494 research outputs found
Difference schemes with point symmetries and their numerical tests
Symmetry preserving difference schemes approximating second and third order
ordinary differential equations are presented. They have the same three or
four-dimensional symmetry groups as the original differential equations. The
new difference schemes are tested as numerical methods. The obtained numerical
solutions are shown to be much more accurate than those obtained by standard
methods without an increase in cost. For an example involving a solution with a
singularity in the integration region the symmetry preserving scheme, contrary
to standard ones, provides solutions valid beyond the singular point.Comment: 26 pages 7 figure
Educational Strategies to Promote Adherence to Treatment in Patients with Cardiovascular Disease
Introduction: Educational material is a key strategy for primary health care promotion. Purpose: To design and validate educational material adapted to the population and aimed to increase knowledge about adherence to the treatment of arterial hypertension and diabetes mellitus. Methodology: Methodological study for the design of educational material for people with diabetes mellitus and high blood pressure. For the design, content validity tests were carried out, with the participation of six experts in health education and six patients with chronic diseases. Validation was performed pursuant to the attraction, understanding, engagement, and acceptance criteria. Results: The validation confirmed that all items and criteria were above the minimal expected range. Conclusion: The design and validation of educational material provide elements that improve the education of patients about their pathologies and their adherence to treatment
Phenomenology of neutral heavy leptons
We continue our previous work on the flavour-conserving leptonic decays of
the Z boson with neutral heavy leptons (NHL's) in the loops by considering box,
vertex, and self-energy diagrams for the muon decay. By inclusion of these
loops (they contribute to the input parameter M_W) we can probe the full
parameter space spanned by the so-called flavour-conserving mixing parameters
ee_(mix), \mu\mu_(mix), \tau\tau_(mix) in a superstring-inspired model of
neutrino mass. We compare the results of our analysis with the existing work in
this field and conclude that flavour-conserving decays have certain advantages
over traditionally considered flavour-violating ones.Comment: submitted to Phys. Rev. D, 30 pages, 9 figures (ps), REVTE
Some constraints on neutral heavy leptons from flavor-conserving decays of the Z boson
Small neutrino masses can arise in some grand unified models or superstring
theories. We consider a model with an enhanced fermion sector containing Dirac
neutral heavy leptons. The dependence on the mass and mixing parameters of
these new fermions is investigated for several measurable quantities. We study
the flavor-conserving leptonic decays of the Z boson and universality breaking
in these decays. We also consider the W boson mass dependence on neutral heavy
lepton parameters.Comment: 20 pages, Revtex 3.0, 6 uuencoded and compressed postscript figures
included. Compressed postscript file of paper, including figures, also
available by anonymous ftp at
ftp://ftp.physics.carleton.ca/pub/theory/gour/ocipc9411.ps.Z . Accepted for
publication in Phys. Rev. D
Search for giant planets in M67 I. Overview
Precise stellar radial velocities are used to search for massive (Jupiter
masses or higher) exoplanets around the stars of the open cluster M67. We aim
to obtain a census of massive exoplanets in a cluster of solar metallicity and
age in order to study the dependence of planet formation on stellar mass and to
compare in detail the chemical composition of stars with and without planets.
This first work presents the sample and the observations, discusses the cluster
characteristics and the radial velocity (RV) distribution of the stars, and
individuates the most likely planetary host candidates. We observed a total of
88 main-sequence stars, subgiants, and giants all highly probable members of
M67, using four telescopes and instrument combinations. We investigate whether
exoplanets are present by obtaining radial velocities with precisions as good
as 10 m/s. To date, we have performed 680 single observations (Dec. 2011) and a
preliminary analysis of data, spanning a period of up to eight years. Although
the sample was pre-selected to avoid the inclusion of binaries, we identify 11
previously unknown binary candidates. Eleven stars clearly displayed larger RV
variability and these are candidates to host long-term substellar companions.
The average RV is also independent of the stellar magnitude and evolutionary
status, confirming that the difference in gravitational redshift between giants
and dwarfs is almost cancelled by the atmospheric motions. We use the subsample
of solar-type stars to derive a precise true RV for this cluster. We finally
create a catalog of binaries and use it to clean the color magnitude diagram
(CMD). As conclusion, by pushing the search for planets to the faintest
possible magnitudes, it is possible to observe solar analogues in open
clusters, and we propose 11 candidates to host substellar companions.Comment: 11 pages, 10 figure
Lithium-rich giants in the Galactic thick disk
Context: Lithium is a fragile element, which is easily destroyed in the
stellar interior. The existence of lithium-rich giants still represents a
challenge for stellar evolution models. Aims: We have collected a large
database of high-resolution stellar spectra of 824 candidate thick-disk giants
having 2\,MASS photometry and proper motions measured by the Southern
Proper-Motion Program (SPM). In order to investigate the nature of Li-rich
giants, we searched this database for giants presenting a strong Li\,I
resonance line. Methods: We performed a chemical abundance analysis on the
selected stars with the MOOG code along with proper ATLAS-9 model atmospheres.
The iron content and atmospheric parameters were fixed by using the equivalent
width of a sample of Fe lines. We also derive abundances for C, N, and O and
measure or derive lower limits on the C/C isotopic ratios, which
is a sensible diagnostic of the stars evolutionary status. Results: We detected
five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to
the current definition. One of them (SPM-313132) has A(Li)3.3 and, because
of this, belongs to the group of the rare super Li-rich giants. Its kinematics
makes it a likely thin-disk member and its atmospheric parameters are
compatible with it being a 4\,M star either on the red giant branch
(RGB) or the early asymptotic giant branch. This object is the first super
Li-rich giant detected at this phase. The other four are likely low-mass
thick-disk stars evolved past the RGB luminosity bump, as determined from their
metallicities and atmospheric parameters. The most evolved of them lies close
to the RGB-tip. It has A(Li)2.7 and a low C/C isotopic ratio,
close to the cool bottom processing predictions.Comment: 11 pages, 7 tables, 7 figures. Accepted for publication in A&
The SOPHIE search for northern extrasolar planets. V. Follow-up of ELODIE candidates: Jupiter-analogs around Sun-like stars
We present radial-velocity measurements obtained in a programs underway to
search for extrasolar planets with the spectrograph SOPHIE at the 1.93-m
telescope of the Haute-Provence Observatory. Targets were selected from
catalogs observed with ELODIE, mounted previously at the telescope, in order to
detect long-period planets with an extended database close to 15 years. Two new
Jupiter-analog candidates are reported to orbit the bright stars HD150706 and
HD222155 in 16.1 and 10.9 yr at 6.7 (+4.0,-1.4) and 5.1(+0.6,-0.7) AU and to
have minimum masses of 2.71 (+1.44,-0.66) and 1.90 (+0.67,-0.53) M_Jup,
respectively. Using the measurements from ELODIE and SOPHIE, we refine the
parameters of the long-period planets HD154345b and HD89307b, and publish the
first reliable orbit for HD24040b. This last companion has a minimum mass of
4.01 +/- 0.49 M_Jup orbiting its star in 10.0 yr at 4.92 +/- 0.38 AU. Moreover,
the data provide evidence of a third bound object in the HD24040 system. With a
surrounding dust debris disk, HD150706 is an active G0 dwarf for which we
partially corrected the effect of the stellar spot on the SOPHIE
radial-velocities. HD222155 is an inactive G2V star. On the basis of the
previous findings of Lovis and collaborators and since no significant
correlation between the radial-velocity variations and the activity index are
found in the SOPHIE data, these variations are not expected to be only due to
stellar magnetic cycles. Finally, we discuss the main properties of this new
population of long-period Jupiter-mass planets, which for the moment, consists
of fewer than 20 candidates. These stars are preferential targets either for
direct-imaging or astrometry follow-up to constrain the system parameters and
for higher precision radial-velocity to search for lower mass planets, aiming
to find a Solar System twin.Comment: accepted for publication in Astronomy & Astrophysic
Transcription of toll-like receptors 2, 3, 4 and 9, FoxP3 and Th17 cytokines in a susceptible experimental model of canine Leishmania infantum infection
Canine leishmaniosis (CanL) due to Leishmania infantum is a chronic zoonotic systemic disease resulting from complex interactions between protozoa and the canine immune system. Toll-like receptors (TLRs) are essential components of the innate immune system and facilitate the early detection of many infections. However, the role of TLRs in CanL remains unknown and information describing TLR transcription during infection is extremely scarce. The aim of this research project was to investigate the impact of L. infantum infection on canine TLR transcription using a susceptible model. The objectives of this study were to evaluate transcription of TLRs 2, 3, 4 and 9 by means of quantitative reverse transcription polymerase chain reaction (qRT-PCR) in skin, spleen, lymph node and liver in the presence or absence of experimental L. infantum infection in Beagle dogs. These findings were compared with clinical and serological data, parasite densities in infected tissues and transcription of IL-17, IL-22 and FoxP3 in different tissues in non-infected dogs (n = 10), and at six months (n = 24) and 15 months (n = 7) post infection. Results revealed significant down regulation of transcription with disease progression in lymph node samples for TLR3, TLR4, TLR9, IL-17, IL-22 and FoxP3. In spleen samples, significant down regulation of transcription was seen in TLR4 and IL-22 when both infected groups were compared with controls. In liver samples, down regulation of transcription was evident with disease progression for IL-22. In the skin, upregulation was seen only for TLR9 and FoxP3 in the early stages of infection. Subtle changes or down regulation in TLR transcription, Th17 cytokines and FoxP3 are indicative of the silent establishment of infection that Leishmania is renowned for. These observations provide new insights about TLR transcription, Th17 cytokines and Foxp3 in the liver, spleen, lymph node and skin in CanL and highlight possible markers of disease susceptibility in this model
Pseudopodium-enriched atypical kinase 1 mediates angiogenesis by modulating GATA2-dependent VEGFR2 transcription
PEAK1 is a newly described tyrosine kinase and scaffold protein that transmits integrin-mediated extracellular matrix (ECM) signals to facilitate cell movement and growth. While aberrant expression of PEAK1 has been linked to cancer progression, its normal physiological role in vertebrate biology is not known. Here we provide evidence that PEAK1 plays a central role in orchestrating new vessel formation in vertebrates. Deletion of the PEAK1 gene in zebrafish, mice, and human endothelial cells (ECs) induced severe defects in new blood vessel formation due to deficiencies in EC proliferation, survival, and migration. Gene transcriptional and proteomic analyses of PEAK1-deficient ECs revealed a significant loss of vascular endothelial growth factor receptor 2 (VEGFR2) mRNA and protein expression, as well as downstream signaling to its effectors, ERK, Akt, and Src kinase. PEAK1 regulates VEGFR2 expression by binding to and increasing the protein stability of the transcription factor GATA-binding protein 2 (GATA2), which controls VEGFR2 transcription. Importantly, PEAK1-GATA2-dependent VEGFR2 expression is mediated by EC adhesion to the ECM and is required for breast cancer-induced new vessel formation in mice. Also, elevated expression of PEAK1 and VEGFR2 mRNA are highly correlated in many human cancers including breast cancer. Together, our findings reveal a novel PEAK1-GATA2-VEGFR2 signaling axis that integrates cell adhesion and growth factor cues from the extracellular environment necessary for new vessel formation during vertebrate development and cancer.NIHNCIAHANIGMS/NIHRay Thomas Edwards FoundationUniv Calif San Diego, Dept Pathol, La Jolla, CA 92093 USAUniv Calif San Diego, Moores Canc Ctr, La Jolla, CA 92093 USAUniv Calif San Diego, Dept Pharmacol, La Jolla, CA 92093 USAUniv Calif San Diego, Skaggs Sch Pharm & Pharmaceut Sci, La Jolla, CA 92093 USAUniv Calif San Diego, Dept Med, La Jolla, CA 92093 USAUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilUniv Calif San Diego, Sanford Consortium Regenerat Med, La Jolla, CA 92093 USAComenius Univ, Jessenius Fac Med Martin, Dept Mol Med, Biomed Ctr Martin, Martin 03601, SlovakiaUniv Fed Sao Paulo, Dept Biochem, Sao Paulo, SP, BrazilNIH: CA182495NIH: CA184594NIH: CA097022NIH: HL135737NIH: CA050286NCI: CA180374AHA: 16POST27250126NIGMS/NIH: K12GM068524Web of Scienc
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