2,809 research outputs found
Planning Instrumentation Monitoring in Dams
This paper outlines the seismic instrumentation being adopted for river valley projects in India, More than 60% of Indian sub-continent lies in an active seismic belt. Of this the middle and lower Himalayas constitute a major area wherein lies a huge untapped hydro-power potential, Being primarily constituted of younger rock formations, frequented by faults, thursts and shear zones and lying in a high seismic risk zone, observations through instruments play a significant role in perspective planning of projects in this area. Setting up of seismological observatories in advance of construction of dam projects, forms a part of investigative planning to assess the seismic status of the area. The observations are continued after construction to monitor any changes in seismicity due to reservoir impounding. Present approach is to also provide instrumentation and continued observation to a possible prediction of earthquake. A typical case of instrumentation for a dam on active fault is also cited
The temperature dependent bandstructure of a ferromagnetic semiconductor film
The electronic quasiparticle spectrum of a ferromagnetic film is investigated
within the framework of the s-f model. Starting from the exact solvable case of
a single electron in an otherwise empty conduction band being exchange coupled
to a ferromagnetically saturated localized spin system we extend the theory to
finite temperatures. Our approach is a moment-conserving decoupling procedure
for suitable defined Green functions. The theory for finite temperatures
evolves continuously from the exact limiting case. The restriction to zero
conduction band occupation may be regarded as a proper model description for
ferromagnetic semiconductors like EuO and EuS. Evaluating the theory for a
simple cubic film cut parallel to the (100) crystal plane, we find some marked
correlation effects which depend on the spin of the test electron, on the
exchange coupling, and on the temperature of the local-moment system.Comment: 11 pages, 9 figure
Universal Scaling in Non-equilibrium Transport Through a Single-Channel Kondo Dot
Scaling laws and universality play an important role in our understanding of
critical phenomena and the Kondo effect. Here we present measurements of
non-equilibrium transport through a single-channel Kondo quantum dot at low
temperature and bias. We find that the low-energy Kondo conductance is
consistent with universality between temperature and bias and characterized by
a quadratic scaling exponent, as expected for the spin-1/2 Kondo effect. The
non-equilibrium Kondo transport measurements are well-described by a universal
scaling function with two scaling parameters.Comment: v2: improved introduction and theory-experiment comparsio
CLINICAL AND BIOCHEMICAL PROFILE OF STEROID-INDUCED DIABETES
ABSTRACTObjective: To study the clinical and biochemical profile of patients who develop steroid-induced diabetes (SID) and its predisposing factors.Methods: Non-diabetic patients aged ≥18 years started on steroids were considered eligible for the study. In every case after detailed examination,fasting plasma glucose (FPG), post-prandial plasma glucose (PPG), glycated hemoglobin, fasting insulin were measured prior to starting steroids andwas repeated in 1 week (day 3/4) after starting steroid according to standard guidelines. FPG and PPG were repeated periodically during follow-upof the patients. The utility of Indian diabetic risk score (IDRS) score in predicting the risk for SID was also assessed.stResult: Steroid-induced diabetes was found to be more in females than in males. IDRS is not useful in predicting the risk factors of SID. 97% of patientshad an elevation of post-prandial sugars with or without fasting hyperglycemia, but only 3% of patients had isolated elevation of fasting blood sugar.84% of patients developed SID during the 1 week of therapy. 33% of the cases SID persisted even after 1 month of stopping steroids and on a minimaldosage of steroids.stConclusion: Unlike type 2 diabetes, there were no significant risk factors such as age, family history of diabetes to develop SID and IDRS may not be asensitive tool for predicting risk factors of SID. Monitoring of post-prandial sugars as compared to fasting sugars is essential for the screening of SID.Cumulative dose of steroid may not be important to precipitate steroid diabetes.Keywords: Glucocorticoids, Diabetes, Post-prandial glucose, Indian Diabetic Risk Score
BRONCHOCONSTRICTION SECONDARY TO USE OF TOPICAL TIMOLOL IN A NON-ASTHMATIC PATIENT
Ophthalmic application of a non-selective beta blocker like timolol maleate is known to produce bronchoconstriction in asthmatic individuals or patients with obstructive lung diseases. Timolol-induced bronchoconstriction in a previously healthy young adult without any pulmonary disease is rare. We report a case of a young adult who developed bronchoconstriction following ocular instillation of timolol maleate ophthalmic solution when he was treated for open-angle glaucoma
Interactive decision support in hepatic surgery
BACKGROUND: Hepatic surgery is characterized by complicated operations with a significant peri- and postoperative risk for the patient. We developed a web-based, high-granular research database for comprehensive documentation of all relevant variables to evaluate new surgical techniques. METHODS: To integrate this research system into the clinical setting, we designed an interactive decision support component. The objective is to provide relevant information for the surgeon and the patient to assess preoperatively the risk of a specific surgical procedure. Based on five established predictors of patient outcomes, the risk assessment tool searches for similar cases in the database and aggregates the information to estimate the risk for an individual patient. RESULTS: The physician can verify the analysis and exclude manually non-matching cases according to his expertise. The analysis is visualized by means of a Kaplan-Meier plot. To evaluate the decision support component we analyzed data on 165 patients diagnosed with hepatocellular carcinoma (period 1996–2000). The similarity search provides a two-peak distribution indicating there are groups of similar patients and singular cases which are quite different to the average. The results of the risk estimation are consistent with the observed survival data, but must be interpreted with caution because of the limited number of matching reference cases. CONCLUSION: Critical issues for the decision support system are clinical integration, a transparent and reliable knowledge base and user feedback
Spitzer Observations of the New Luminous Red Nova M85OT2006-1
M85OT2006-1 is the latest and most brilliant addition to the small group of
known Luminous Red Novae (LRNe). An identifying characteristic of the
previously detected events (M31 RV, V4322 Sgr & V838 Mon) was a spectral
red-ward evolution connected with an emerging infrared component following the
optical decay. Here we report on the discovery of a similar feature in
Keck/NIRC and Spitzer photometry of M85OT2006-1 six months post-eruption. We
find that its 2.1-22 micrometer spectral energy distribution is best described
by a black body with effective temperature T_eff=950+-150 K and bolometric
luminosity L=2.9+-0.5x10^5 L_sun. Assuming spherical geometry, the black body
effective radius, R=2.0+-0.5x10^4 R_sun, and corresponding expansion velocity,
v=870+-260 km/s, are remarkably similar to the properties of M31 RV 70 days
after its eruption. Furthermore, we propose a search strategy for LRNe in the
local Universe making use of the longevity of their infrared excess emission
and discuss the expected number of events in the Spitzer Infrared Nearby
Galaxies Survey.Comment: manuscript after minor revisions, accepted for Ap
The Environment of M85 optical transient 2006-1: constraints on the progenitor age and mass
M85 optical transient 2006-1 (M85 OT 2006-1) is the most luminous member of
the small family of V838 Mon-like objects, whose nature is still a mystery.
This event took place in the Virgo cluster of galaxies and peaked at an
absolute magnitude of I~-13. Here we present Hubble Space Telescope images of
M85 OT 2006-1 and its environment, taken before and after the eruption, along
with a spectrum of the host galaxy at the transient location. We find that the
progenitor of M85 OT 2006-1 was not associated with any star forming region.
The g and z-band absolute magnitudes of the progenitor were fainter than about
-4 and -6 mag, respectively. Therefore, we can set a lower limit of ~50 Myr on
the age of the youngest stars at the location of the progenitor that
corresponds to a mass of <7 solar mass. Previously published line indices
suggest that M85 has a mean stellar age of 1.6+/-0.3 Gyr. If this mean age is
representative of the progenitor of M85 OT 2006-1, then we can further
constrain its mass to be less than 2 solar mass. We compare the energetics and
mass limit derived for the M85 OT 2006-1 progenitor with those expected from a
simple model of violent stellar mergers. Combined with further modeling, these
new clues may ultimately reveal the true nature of these puzzling events.Comment: 4 pages, accepted to Ap
The Microchannel X-ray Telescope on Board the SVOM Satellite
We present the Micro-channel X-ray Telescope (MXT), a new narrow-field (about
1{\deg}) telescope that will be flying on the Sino-French SVOM mission
dedicated to Gamma-Ray Burst science, scheduled for launch in 2021. MXT is
based on square micro pore optics (MPOs), coupled with a low noise CCD. The
optics are based on a "Lobster Eye" design, while the CCD is a focal plane
detector similar to the type developed for the seven eROSITA telescopes. MXT is
a compact and light (<35 kg) telescope with a 1 m focal length, and it will
provide an effective area of about 45 cmsq on axis at 1 keV. The MXT PSF is
expected to be better than 4.2 arc min (FWHM) ensuring a localization accuracy
of the afterglows of the SVOM GRBs to better than 1 arc min (90\% c.l. with no
systematics) provided MXT data are collected within 5 minutes after the
trigger. The MXT sensitivity will be adequate to detect the afterglows for
almost all the SVOM GRBs as well as to perform observations of non-GRB
astrophysical objects. These performances are fully adapted to the SVOM science
goals, and prove that small and light telescopes can be used for future small
X-ray missions.Comment: 6 pages, 6 figures, proceedings of the conference "Swift: 10 years of
Discovery", Rome, December 2-5, 2014. To be published by Po
The s Process: Nuclear Physics, Stellar Models, Observations
Nucleosynthesis in the s process takes place in the He burning layers of low
mass AGB stars and during the He and C burning phases of massive stars. The s
process contributes about half of the element abundances between Cu and Bi in
solar system material. Depending on stellar mass and metallicity the resulting
s-abundance patterns exhibit characteristic features, which provide
comprehensive information for our understanding of the stellar life cycle and
for the chemical evolution of galaxies. The rapidly growing body of detailed
abundance observations, in particular for AGB and post-AGB stars, for objects
in binary systems, and for the very faint metal-poor population represents
exciting challenges and constraints for stellar model calculations. Based on
updated and improved nuclear physics data for the s-process reaction network,
current models are aiming at ab initio solution for the stellar physics related
to convection and mixing processes. Progress in the intimately related areas of
observations, nuclear and atomic physics, and stellar modeling is reviewed and
the corresponding interplay is illustrated by the general abundance patterns of
the elements beyond iron and by the effect of sensitive branching points along
the s-process path. The strong variations of the s-process efficiency with
metallicity bear also interesting consequences for Galactic chemical evolution.Comment: 53 pages, 20 figures, 3 tables; Reviews of Modern Physics, accepte
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