1,402 research outputs found
Adoption and impacts of zero tillage as a resource conserving technology in the irrigated plains of South Asia
Zero tillage / Rice / Wheat / Water conservation / India / Pakistan / Haryana / Punjab
Teleparallel Energy-Momentum Distribution of Spatially Homogeneous Rotating Spacetimes
The energy-momentum distribution of spatially homogeneous rotating spacetimes
in the context of teleparallel theory of gravity is investigated. For this
purpose, we use the teleparallel version of Moller prescription. It is found
that the components of energy-momentum density are finite and well-defined but
are different from General Relativity. However, the energy-momentum density
components become the same in both theories under certain assumptions. We also
analyse these quantities for some special solutions of the spatially
homogeneous rotating spacetimes.Comment: 12 pages, accepted for publication in Int. J. Theor. Phy
The Energy of Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics
According to the Einstein, Weinberg, and M{\o}ller energy-momentum complexes,
we evaluate the energy distribution of the singularity-free solution of the
Einstein field equations coupled to a suitable nonlinear electrodynamics
suggested by Ay\'{o}n-Beato and Garc\'{i}a. The results show that the energy
associated with the definitions of Einstein and Weinberg are the same, but
M{\o}ller not. Using the power series expansion, we find out that the first two
terms in the expression are the same as the energy distributions of the
Reissner-Nordstr\"{o}m solution, and the third term could be used to survey the
factualness between numerous solutions of the Einstein field eqautions coupled
to a nonlinear electrodynamics.Comment: 11 page
Matter collineations of Spacetime Homogeneous G\"odel-type Metrics
The spacetime homogeneous G\"odel-type spacetimes which have four classes of
metrics are studied according to their matter collineations. The obtained
results are compared with Killing vectors and Ricci collineations. It is found
that these spacetimes have infinite number of matter collineations in
degenerate case, i.e. det, and do not admit proper matter
collineations in non-degenerate case, i.e. det. The degenerate
case has the new constraints on the parameters and which characterize
the causality features of the G\"odel-type spacetimes.Comment: 12 pages, LaTex, no figures, Class. Quantum.Grav.20 (2003) 216
The Relativistic Generalization of the Gravitational Force for Arbitrary Spacetimes
It has been suggested that re-expressing relativity in terms of forces could
provide fresh insights. The formalism developed for this purpose only applied
to static, or conformally static, space-times. Here we extend it to arbitrary
space-times. It is hoped that this formalism may lead to a workable definition
of mass and energy in relativity.Comment: 16 page
Bergmann-Thomson energy-momentum complex for solutions more general than the Kerr-Schild class
In a very well-known paper, Virbhadra's research group proved that the
Weinberg, Papapetrou, Landau and Lifshitz, and Einstein energy-momentum
complexes ``coincide'' for all metrics of Kerr-Schild class. A few years later,
Virbhadra clarified that this ``coincidence'' in fact holds for metrics more
general than the Kerr-Schild class. In the present paper, this study is
extended for the Bergmann-Thomson complex and it is proved that this complex
also ``coincides'' with those complexes for a more general than the Kerr-Schild
class metric.Comment: RevTex, 12 page
Analysing an Imbalanced Stroke Prediction Dataset Using Machine Learning Techniques
A stroke is a medical condition characterized by the rupture of blood vessels within the brain which can lead to brain damage. Various symptoms may be exhibited when the brain's supply of blood and essential nutrients is disrupted. To forecast the possibility of brain stroke occurring at an early stage using Machine Learning (ML) and Deep Learning (DL) is the main objective of this study. Timely detection of the various warning signs of a stroke can significantly reduce its severity. This paper performed a comprehensive analysis of features to enhance stroke prediction effectiveness. A reliable dataset for stroke prediction is taken from the Kaggle website to gauge the effectiveness of the proposed algorithm. The dataset has a class imbalance problem which means the total number of negative samples is higher than the total number of positive samples. The results are reported based on a balanced dataset created using oversampling techniques. The proposed work used Smote and Adasyn to handle imbalanced problem for better evaluation metrics. Additionally, the hybrid Neural Network and Random Forest (NN-RF) utilizing the balanced dataset by Adasyn oversampling achieves the highest F1-score of 75% compared to the original unbalanced dataset and other benchmarking algorithms. The proposed algorithm with balanced data utilizing hybrid NN-RF achieves an accuracy of 84%. Advanced ML techniques coupled with thorough data analysis enhance stroke prediction. This study underscores the significance of data-driven methodologies, resulting in improved accuracy and comprehension of stroke risk factors. Applying these methodologies to medical fields can enhance patient care and public health outcomes. By integrating our discoveries, we can enhance the efficiency and effectiveness of the public health system
Vacuum phototriodes for the CMS electromagnetic calorimeter endcap
The measurement of scintillation light from the lead tungstate crystals of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) poses a substantial technical challenge, particularly in the endcap regions, where the radiation levels are highest. The photodetectors must be fast, sensitive, radiationhard, and operate with significant internal gain in a magnetic field of 4 Tesla. The measured performance characteristics of the first batches of series production vacuum phototriodes (VPT), developed to satisfy the needs of CMS, will be described
Teleparallel Energy-Momentum Distribution of Static Axially Symmetric Spacetimes
This paper is devoted to discuss the energy-momentum for static axially
symmetric spacetimes in the framework of teleparallel theory of gravity. For
this purpose, we use the teleparallel versions of Einstein, Landau-Lifshitz,
Bergmann and Mller prescriptions. A comparison of the results shows
that the energy density is different but the momentum turns out to be constant
in each prescription. This is exactly similar to the results available in
literature using the framework of General Relativity. It is mentioned here that
Mller energy-momentum distribution is independent of the coupling
constant . Finally, we calculate energy-momentum distribution for the
Curzon metric, a special case of the above mentioned spacetime.Comment: 14 pages, accepted for publication in Mod. Phys. Lett.
The response to high magnetic fields of the vacuum phototriodes for the compact muon solenoid endcap electromagnetic calorimeter
The endcap electromagnetic calorimeter of the Compact Muon Solenoid (CMS) detects particles with the dense fast scintillator lead tungstate (PbWO4). Due to the low light yield of this scintillator photodetectors with internal gain are required. Silicon avalanche photodiodes cannot be used in the endcap region due to the intense neutron flux. Following an extensive R&D programme 26 mm diameter single-stage photomultipliers (vacuum phototriodes) have been chosen as the photodetector in the endcap region. The first 1400 production devices are currently being evaluated following recent tests of a pre-production batch of 500 tubes. Tubes passing our acceptance tests have responses, averaged over the angular acceptance of the endcap calorimeter, corresponding to the range 20 to 55 electrons per MeV deposited in PbWO4. These phototriodes operate, with a typical gain of 10, in magnetic fields up to 4T.PPARC, EC(INTAS-CERN scheme 99-424
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