341 research outputs found
Notes on the diet of the Cuban Flat-headed Frog, Eleutherodactylus planirostris (Eleutherodactylidae) from two understudied habitats in Western Cuba
Nitric oxide modulates interleukin-2-induced proliferation in CTLL-2 cells
The role of the L-arginine–nitric oxide metabolic pathway was explored for interleukin-2-induced proliferation in the cytotoxic T lymphocyte clone CTLL-2. Specific inhibition of nitric oxide synthase significantly diminished, in a concentration-dependent manner, 3H-thymidine uptake of CTLL-2 cells in response to different concentrations of interleukin 2. Withdrawal of L-arginine from culture medium resulted as potent as the higher inhibition obtained when blocking nitric oxide synthase with L-arginine analogues. Furthermore, intermedial concentrations of Larginine and exogenous nitric oxide donors were found for achieving optimal IL2-induced proliferation of CTLL-2. These findings prompted us to suggest that intra- and/or inter-cellular nitric oxide signalling may contribute to the modulation of the IL2 mitogenic effect upon cytotoxic T lymphocytes
Poisson-Jacobi reduction of homogeneous tensors
The notion of homogeneous tensors is discussed. We show that there is a
one-to-one correspondence between multivector fields on a manifold ,
homogeneous with respect to a vector field on , and first-order
polydifferential operators on a closed submanifold of codimension 1 such
that is transversal to . This correspondence relates the
Schouten-Nijenhuis bracket of multivector fields on to the Schouten-Jacobi
bracket of first-order polydifferential operators on and generalizes the
Poissonization of Jacobi manifolds. Actually, it can be viewed as a
super-Poissonization. This procedure of passing from a homogeneous multivector
field to a first-order polydifferential operator can be also understood as a
sort of reduction; in the standard case -- a half of a Poisson reduction. A
dual version of the above correspondence yields in particular the
correspondence between -homogeneous symplectic structures on and
contact structures on .Comment: 19 pages, minor corrections, final version to appear in J. Phys. A:
Math. Ge
The HADES RV Programme with HARPS-N at TNG XI. GJ 685 b: a warm super-Earth around an active M dwarf
Small rocky planets seem to be very abundant around low-mass M-type stars.
Their actual planetary population is however not yet precisely understood.
Currently several surveys aim to expand the statistics with intensive detection
campaigns, both photometric and spectroscopic. We analyse 106 spectroscopic
HARPS-N observations of the active M0-type star GJ 685 taken over the past five
years. We combine these data with photometric measurements from different
observatories to accurately model the stellar rotation and disentangle its
signals from genuine Doppler planetary signals in the RV data. We run an MCMC
analysis on the RV and activity indexes time series to model the planetary and
stellar signals present in the data, applying Gaussian Process regression
technique to deal with the stellar activity signals. We identify three periodic
signals in the RV time series, with periods of 9, 24, and 18 d. Combining the
analyses of the photometry of the star with the activity indexes derived from
the HARPS-N spectra, we identify the 18 d and 9 d signals as activity-related,
corresponding to the stellar rotation period and its first harmonic
respectively. The 24 d signals shows no relations with any activity proxy, so
we identify it as a genuine planetary signal. We find the best-fit model
describing the Doppler signal of the newly-found planet, GJ 685\,b,
corresponding to an orbital period d and a
minimum mass M. We also study a
sample of 70 RV-detected M-dwarf planets, and present new statistical evidence
of a difference in mass distribution between the populations of single- and
multi-planet systems, which can shed new light on the formation mechanisms of
low-mass planets around late-type stars.Comment: 18 pages, 13 figures, accepted for publication in A&
Community-Based Population Health Research: A Report from the Field
This Forum, “Community-Based Population Health Research: A Report from the Field” highlights the work of 1889 Jefferson Center for Population Health and Mainline Center for Population Health Research. Leaders from both research centers provide an overview of the history and purpose of the centers and describe accomplishments and current initiatives.
Objectives: Describe two innovative models for population health research centers List three benefits of partnering with a University when establishing a population health center Characterize challenges associated with the development of community-engaged and health system embedded, population health research centers
Presentation: 49:1
Drainage of the hepatic cyst by laparoscopy - clinical case
Liver cysts are formations of serous content surrounded by normal liver parenchyma, without communication with the bile duct. The cyst wall is generally lined with cuboidal epithelium surrounded by layers of connective tissue. They are rare entities in adult patients, generally, they are asymptomatic in 3%, and between 10-15% of all patients will generate symptoms that lead them to consult. A 38-year-old man with an external abdominal tomography study that reported a giant hepatic cyst. Laboratory blood tests: hemoglobin 7.9 g/dl; leukocytosis 11,000/ul; serum electrolytes, liver transaminases, and bilirubin were normal, alkaline phosphatase, and gamma glutamyl-transpeptidase 94 U/l and 241 U/l, respectively. Non-reactive anti-human immuno-deficiency virus (HIV 1) and two antibodies, venereal disease research laboratory (VDRL), cancer antigen (CA) 19-9 antigen, hepatitis B-C surface antigen, and carcinoembryonic antigen were negative. He underwent surgery by laparoscopic drainage of the liver cyst, through a median infraumbilical incision with the Hasson technique and placement of three 12 mm trocars, hepatomegaly was observed without finding an exit site for purulent material, it was punctured through liver segment V, and 2000 ml of citrine fluid was extracted. The hepatic wound is addressed with a 1-0 caliber chromic catgut thread, placing a Penrose-type drain. At 48 hours postoperatively, it evolves favorably, so it is decided to discharge. Hepatic cysts are fluid-filled cavities lined by a single-layered cuboidal or columnar biliary epithelium in the liver. A majority of hepatic cysts are found incidentally on liver imaging, such as abdominal ultrasonography, computed tomography, or magnetic resonance imaging
HADES RV Programme with HARPS-N at TNG. VII. Rotation and activity of M-Dwarfs from time-series high-resolution spectroscopy of chromospheric indicators
We aim to investigate the presence of signatures of magnetic cycles and
rotation on a sample of 71 early M-dwarfs from the HADES RV programme using
high-resolution time-series spectroscopy of the Ca II H & K and Halpha
chromospheric activity indicators, the radial velocity series, the parameters
of the cross correlation function and the V-band photometry. We used mainly
HARPS-N spectra, acquired over four years, and add HARPS spectra from the
public ESO database and ASAS photometry light-curves as support data, extending
the baseline of the observations of some stars up to 12 years. We provide
log(R'hk) measurements for all the stars in the sample, cycle length
measurements for 13 stars, rotation periods for 33 stars and we are able to
measure the semi-amplitude of the radial velocity signal induced by rotation in
16 stars. We complement our work with previous results and confirm and refine
the previously reported relationships between the mean level of chromospheric
emission, measured by the log(R'hk), with the rotation period, and with the
measured semi-amplitude of the activity induced radial velocity signal for
early M-dwarfs. We searched for a possible relation between the measured
rotation periods and the lengths of the magnetic cycle, finding a weak
correlation between both quantities. Using previous v sin i measurements we
estimated the inclinations of the star's poles to the line of sight for all the
stars in the sample, and estimate the range of masses of the planets GJ 3998 b
and c (2.5 - 4.9 Mearth and 6.3 - 12.5 Mearth), GJ 625 b (2.82 Mearth), GJ 3942
b (7.1 - 10.0 Mearth) and GJ 15A b (3.1 - 3.3 Mearth), assuming their orbits
are coplanar with the stellar rotation.Comment: 19 pages, 16 figures, 10 table
CONTRIBUCIÓN DE LA FÍSICA A UNA MEJOR CONCEPTUALIZACIÓN ENERGÉTICA EN ALUMNOS DE INGENIERÍAS
En el presente trabajo se ponen en evidencia importantes deficiencias con relación al concepto general de energía, que manifiestan libros de amplia utilización por los estudiantes de ingenierías durante el primer curso de Física Introductoria. Además se expone un modelo instruccional no tradicional para este aspecto, que según resultados obtenidos de su aplicación en cursos desarrollados en Cuba y México, posibilita erradicar o reducir considerablemente los efectos negativos que en los alumnos suelen generar las dificultades inicialmente referidas
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