779 research outputs found
Conversion of Dynamic High Pressures from Air to Water for a Spherical TNT Charge
A numerical method has been applied to convert the dynamic high pressures from air-to-water for a spherical TNT charge. Standard equation of scaling law in air for TNT has been utilised to make the necessary conversions. The investigations have been made by taking into consideration the ambient pressure values for the two media. The calculations have been performed under the scaled distances to get better results. Experimental measurements using indigenous blast pressure gauge have been undertaken by detonating spherical charges of TNT under the same scaled distances in water to check the correctness of results and direct application of this method. A fairly close agreement between the theoretically computed and the experimental values of the dynamic high pressures shows the practical utility of this approach in that it enables an estimate of the experimental shock wave pressures, without conducting underwater experiments
Management of a case of thromboembolism post spine surgery: a case report
Postoperative deep vein thrombosis (DVT) of lower limbs is often asymptomatic. In many patients, fatal pulmonary embolism (PE) is the first clinical manifestation of postoperative venous thromboembolism (VTE). Routine screening for asymptomatic DVT of the lower limbs has a low sensitivity and is quite impractical. For these reasons, routine and systematic prophylaxis in patients at risk, is the strategy of choice to reduce the burden of VTE after surgery. If used appropriately such prophylaxis is cost effective since it reduces the incidence of symptomatic thromboembolic events, which require costly diagnostic procedures and prolonged anticoagulation therapy. Here we report the post-operative course of a spine surgery patient, presenting with DVT in calf veins, which lodged into pulmonary artery and was managed successfully with low molecular weight heparin (LMWH), embolectomy, inferior vena cava (IVC) filter, and dabigatran
Ewingās sarcoma or peripheral primitive neuroectodermal tumor at the base of tongue: a rare location case report
Peripheral primitive neuroectodermal tumor now termed as Ewings sarcoma/PNET, representing a family of tumors with varying degrees of neuronal differentiation and genetic rearrangements. Most common sites are extraosseous involving trunk and lower limb. Base of tongue is a very rare site for Ewingās/PNET, hence in view of rarity of the location as an uncommon presentation, the case has been reported for the better understanding and supporting the literature with the similar finding. A 68 years old female patient presented with the complaint of difficulty in swallowing since 3 months. On examination growth was identified at the left side base of tongue. Biopsy was processed and stained with H&E and other relevant markers. Differentials on the basis microscopic examination were lymphoma, neuroendocrine tumor and primitive neuroectodermal tumor. Various immunohistochemical markers to rule out the given differential were used. The tumor was positive for CD 99 and vimentin. The case was repored as PNET. Peripheral PNET is a challenging topic. Wide range of extraosseous locations have been observed but head and neck being less reported needs to be studied for understanding the behavior of this highly malignant disease in this rare location so that patient can be benefitted by advanced multimodality treatments including surgery, chemotherapy and radiotherapy
Volatility of Linear and Nonlinear Time Series
Previous studies indicate that nonlinear properties of Gaussian time series
with long-range correlations, , can be detected and quantified by studying
the correlations in the magnitude series , i.e., the ``volatility''.
However, the origin for this empirical observation still remains unclear, and
the exact relation between the correlations in and the correlations in
is still unknown. Here we find analytical relations between the scaling
exponent of linear series and its magnitude series . Moreover, we
find that nonlinear time series exhibit stronger (or the same) correlations in
the magnitude time series compared to linear time series with the same
two-point correlations. Based on these results we propose a simple model that
generates multifractal time series by explicitly inserting long range
correlations in the magnitude series; the nonlinear multifractal time series is
generated by multiplying a long-range correlated time series (that represents
the magnitude series) with uncorrelated time series [that represents the sign
series ]. Our results of magnitude series correlations may help to
identify linear and nonlinear processes in experimental records.Comment: 7 pages, 5 figure
Presence of Many Stable Nonhomogeneous States in an Inertial Car-Following Model
A new single lane car following model of traffic flow is presented. The model
is inertial and free of collisions. It demonstrates experimentally observed
features of traffic flow such as the existence of three regimes: free,
fluctuative (synchronized) and congested (jammed) flow; bistability of free and
fluctuative states in a certain range of densities, which causes the hysteresis
in transitions between these states; jumps in the density-flux plane in the
fluctuative regime and gradual spatial transition from synchronized to free
flow. Our model suggests that in the fluctuative regime there exist many stable
states with different wavelengths, and that the velocity fluctuations in the
congested flow regime decay approximately according to a power law in time.Comment: 4 pages, 4 figure
Computational reconstruction of tissue-specific metabolic models: application to human liver metabolism
The first computational approach for the rapid generation of genome-scale tissue-specific models from a generic species model.A genome scale model of human liver metabolism, which is comprehensively tested and validated using cross-validation and the ability to carry out complex hepatic metabolic functions.The model's flux predictions are shown to correlate with flux measurements across a variety of hormonal and dietary conditions, and are successfully used to predict biomarker changes in genetic metabolic disorders, both with higher accuracy than the generic human model
Lack of association between estrogen receptor Ī² dinucleotide repeat polymorphism and autoimmune thyroid diseases in Japanese patients
BACKGROUND: The autoimmune thyroid diseases (AITDs), such as Graves' disease (GD) and Hashimoto's thyroiditis (HT), appear to develop as a result of complex interactions between predisposing genes and environmental triggers. Susceptibility to AITDs is conferred by genes in the human leukocyte antigen (HLA) and genes unlinked to HLA, including the CTLA-4 gene. Recently, estrogen receptor (ER) Ī², located at human chromosome 14q23-24.1, was identifed. We analyzed a dinucleotide (CA)n repeat polymorphism located in the flanking region of ERĪ² gene in patients with AITDs and in normal subjects. High heterozygosity makes this polymorphism a useful marker in the genetic study of disorders affecting female endocrine systems. We also correlated a ERĪ² gene microsatellite polymorphism with bone mineral density (BMD) in the distal radius and biochemical markers of bone turnover in patients with GD in remission. RESULTS: Fourteen different alleles were found in 133 patients with GD, 114 patients with HT, and 179 controls subjects. The various alleles were designated as allele(*)1 through allele(*)14 according to the number of the repeats, from 18 to 30. There was no significant difference in the distributions of ERĪ² alleles between patient groups and controls. Although recent study demonstrated a significant relation between a allele(*)9 in the ERĪ² gene and BMD in postmenopausal Japanese women, there were no statistically significant interaction between this allele and BMD in the distal radius, nor biochemical markers in patients with GD in remission. CONCLUSIONS: The present results do not support an association between the ERĪ² microsatellite marker and AITD in the Japanese population. We also suggest that the ERĪ² microsatellite polymorphism has at most a minor pathogenic importance in predicting the risk of osteoporosis as a complication of GD
Towards a variational principle for motivated vehicle motion
We deal with the problem of deriving the microscopic equations governing the
individual car motion based on the assumptions about the strategy of driver
behavior. We suppose the driver behavior to be a result of a certain compromise
between the will to move at a speed that is comfortable for him under the
surrounding external conditions, comprising the physical state of the road, the
weather conditions, etc., and the necessity to keep a safe headway distance
between the cars in front of him. Such a strategy implies that a driver can
compare the possible ways of his further motion and so choose the best one. To
describe the driver preferences we introduce the priority functional whose
extremals specify the driver choice. For simplicity we consider a single-lane
road. In this case solving the corresponding equations for the extremals we
find the relationship between the current acceleration, velocity and position
of the car. As a special case we get a certain generalization of the optimal
velocity model similar to the "intelligent driver model" proposed by Treiber
and Helbing.Comment: 6 pages, RevTeX
Phase diagram of congested traffic flow: an empirical study
We analyze traffic data from a highway section containing one effective
on-ramp. Based on two criteria, local velocity variation patterns and expansion
(or nonexpansion) of congested regions, three distinct congested traffic states
are identified. These states appear at different levels of the upstream flux
and the on-ramp flux, thereby generating a phase diagram of the congested
traffic flow. Compared to our earliear reports (including cond-mat/9905292)
based on 14 day traffic data, the present paper uses a much larger data set
(107 days) and the analysis is carried in a more systematic way, which leads to
the modification of a part of interpretation in the earlier reports. Observed
traffic states are compared with recent theoretical analyses and both agreeing
and disagreeing features are found.Comment: More extensive and systematic version of earlier reports (including
cond-mat/9905292). A part of interpretation in earlier reports is modified. 6
two-column pages. To appear in Phys. Rev. E (tentatively scheduled for Oct. 1
issue
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