152 research outputs found
On the origin of comets
Physico-chemical processes leading to the dynamic formation and physical evolution of comets are reviewed in relationship to the various theories that propose solar origins, protoplanetary origins, planetary origins and interstellar origins. Evidence points to the origins of comets by the growth and agglomeration of small particles from gas and dust at very low temperatures at undetermined regions in space
Expanding horizons of anticoagulant therapy: Dabigatran etexilate a novel oral anticoagulant
Thrombo-embolic disease is a major challenging clinical problem associated with significant mortality and morbidity. Anticoagulation with the existing heparin products and vitamin K antagonist (VKA) anticoagulants are still the mainstay of management. However, due to the risk of bleeding and well-documented drawbacks, the quest for a novel oral anticoagulant has led to the clinical development of dabigatran etexilate. Dabigatran etexilate is a direct thrombin (IIa) inhibitor which has recently been approved in India for prevention of venous thromboembolic events (VTE) in patients who have undergone major orthopaedic (total knee or hip replacement) surgery and for prevention of stroke, systemic embolism and reduction of vascular mortality in adult patients with atrial fibrillation. Thus dabigatran etexilate is a promising alternative to the current heparin products and VKAs in patients who require long-term oral anticoagulation
A Minimum-Mass Extrasolar Nebula
By analogy with the minimum-mass solar nebula, we construct a surface-density
profile using the orbits of the 26 precise-Doppler planets found in multiple
planet systems: Sigma = 2200 grams per square centimeter (a/1 AU)^- beta, where
a is the circumstellar radius, and beta = 2.0 plus or minus 0.5. The
minimum-mass solar nebula is consistent with this model, but the uniform-alpha
accretion disk model is not. In a nebula with beta > 2, the center of the disk
is the likely cradle of planet formation.Comment: 15 pages, including 2 figures. To appear in ApJ, 9/04 new version
with prettier page layou
Winds, B-Fields, and Magnetotails of Pulsars
We investigate the emission of rotating magnetized neutron stars due to the
acceleration and radiation of particles in the relativistic wind and in the
magnetotail of the star. We consider that the charged particles are accelerated
by driven collisionless reconnection. Outside of the light cylinder, the star's
rotation acts to wind up the magnetic field to form a predominantly azimuthal,
slowly decreasing with distance, magnetic field of opposite polarity on either
side of the equatorial plane normal to the star's rotation axis. The magnetic
field annihilates across the equatorial plane with the magnetic energy going to
accelerate the charged particles to relativistic energies. For a typical
supersonically moving pulsar, the star's wind extends outward to the standoff
distance with the interstellar medium. At larger distances, the power output of
pulsar's wind of electromagnetic field and relativistic particles
is {\it redirected and collimated into the magnetotail} of the star. In the
magnetotail it is proposed that equipartition is reached between the magnetic
energy and the relativistic particle energy. For such conditions, synchrotron
radiation from the magnetotails may be a significant fraction of
for high velocity pulsars. An equation is derived for the radius of the
magnetotail as a function of distance from the star.
For large distances , of the order of the distance travelled by the
star, we argue that the magnetotail has a `trumpet' shape owing to the slowing
down of the magnetotail flow.Comment: 11 pages, 4 figures, accepted for publication in Ap
Reports of planetary geology program, 1977-1978
A compilation of abstracts of reports which summarizes work conducted by Planetary Geology Principal Investigators and their associates is presented. Full reports of these abstracts were presented to the annual meeting of Planetary Geology Principal Investigators and their associates at the Universtiy of Arizona, Tucson, Arizona, May 31, June 1 and 2, 1978
Cadmium accumulation and interactions with zinc, copper, and manganese, analysed by ICP-MS in a long-term Caco-2 TC7 cell model
The influence of long-term exposure to cadmium (Cd) on essential minerals was investigated using a Caco-2
TC7 cells and a multi-analytical tool: microwave digestion and inductively coupled plasma mass spectrometry.
Intracellular levels, effects on cadmium accumulation, distribution, and reference concentration
ranges of the following elements were determined: Na, Mg, Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo, and Cd.
Results showed that Caco-2 TC7 cells incubated long-term with cadmium concentrations ranging from 0 to
10 lmol Cd/l for 5 weeks exhibited a significant increase in cadmium accumulation. Furthermore, this
accumulation was more marked in cells exposed long-term to cadmium compared with controls, and that
this exposure resulted in a significant accumulation of copper and zinc but not of the other elements
measured. Interactions of Cd with three elements: zinc, copper, and manganese were particularly studied.
Exposed to 30 lmol/l of the element, manganese showed the highest inhibition and copper the lowest on
cadmium intracellular accumulation but Zn, Cu, and Mn behave differently in terms of their mutual
competition with Cd. Indeed, increasing cadmium in the culture medium resulted in a gradual and significant
increase in the accumulation of zinc. There was a significant decrease in manganese from 5 lmol
Cd/l exposure, and no variation was observed with copper.
Abbreviation: AAS – Atomic absorption spectrometry; CRM– Certified reference material; PBS – Phosphate
buffered saline without calcium and magnesium; DMEM – Dubelcco’s modified Eagle’s medium
Milestones in the Observations of Cosmic Magnetic Fields
Magnetic fields are observed everywhere in the universe. In this review, we
concentrate on the observational aspects of the magnetic fields of Galactic and
extragalactic objects. Readers can follow the milestones in the observations of
cosmic magnetic fields obtained from the most important tracers of magnetic
fields, namely, the star-light polarization, the Zeeman effect, the rotation
measures (RMs, hereafter) of extragalactic radio sources, the pulsar RMs, radio
polarization observations, as well as the newly implemented sub-mm and mm
polarization capabilities.
(Another long paragraph is omitted due to the limited space here)Comment: Invited Review (ChJA&A); 32 pages. Sorry if your significant
contributions in this area were not mentioned. Published pdf & ps files (with
high quality figures) now availble at http://www.chjaa.org/2002_2_4.ht
The East-West method: an exposure-independent method to search for large scale anisotropies of cosmic rays
The measurement of large scale anisotropies in cosmic ray arrival directions
at energies above 10^13 eV is performed through the detection of Extensive Air
Showers produced by cosmic ray interactions in the atmosphere. The observed
anisotropies are small, so accurate measurements require small statistical
uncertainties, i.e. large datasets. These can be obtained by employing ground
detector arrays with large extensions (from 10^4 to 10^9 m^2) and long
operation time (up to 20 years). The control of such arrays is challenging and
spurious variations in the counting rate due to instrumental effects (e.g. data
taking interruptions or changes in the acceptance) and atmospheric effects
(e.g. air temperature and pressure effects on EAS development) are usually
present. These modulations must be corrected very precisely before performing
standard anisotropy analyses, i.e. harmonic analysis of the counting rate
versus local sidereal time. In this paper we discuss an alternative method to
measure large scale anisotropies, the "East-West method", originally proposed
by Nagashima in 1989. It is a differential method, as it is based on the
analysis of the difference of the counting rates in the East and West
directions. Besides explaining the principle, we present here its mathematical
derivation, showing that the method is largely independent of experimental
effects, that is, it does not require corrections for acceptance and/or for
atmospheric effects. We explain the use of the method to derive the amplitude
and phase of the anisotropy and we demonstrate its power under different
conditions of detector operation
Introducing a New Algorithm for Classification of Etiology in Studies on Pediatric Pneumonia: Protocol for the Trial of Respiratory Infections in Children for Enhanced Diagnostics Study
Background: There is a need to better distinguish viral infections from antibiotic-requiring bacterial infections in children presenting with clinical community-acquired pneumonia (CAP) to assist health care workers in decision making and to improve the rational use of antibiotics.Objective: The overall aim of the Trial of Respiratory infections in children for ENhanced Diagnostics (TREND) study is to improve the differential diagnosis of bacterial and viral etiologies in children aged below 5 years with clinical CAP, by evaluating myxovims resistance protein A (MxA) as a biomarker for viral CAP and by evaluating an existing (multianalyte point-of-care antigen detection test system [mariPOC respi] ArcDia International Oy Ltd.) and a potential future point-of-care test for respiratory pathogens.Methods: Children aged 1 to 59 months with clinical CAP as well as healthy, hospital-based, asymptomatic controls will be included at a pediatric emergency hospital in Stockholm, Sweden. Blood (analyzed for MxA and C-reactive protein) and nasopharyngeal samples (analyzed with real-time polymerase chain reaction as the gold standard and antigen-based mariPOC respi test as well as saved for future analyses of a novel recombinase polymerase amplification-based point-of-care test for respiratory pathogens) will be collected. A newly developed algorithm for the classification of CAP etiology will be used as the reference standard.Results: A pilot study was performed from June to August 2017. The enrollment of study subjects started in November 2017. Results are expected by the end of 2019.Conclusions: The findings from the TREND study can be an important step to improve the management of children with clinical CAP
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