Electrostatic Structures in Space Plasmas: Stability of Two-dimensional Magnetic Bernstein-Greene-Kruskal Modes

Electrostatic structures have been observed in many regions of space plasmas, including the solar wind, the magnetosphere, the auroral acceleration region, and in association with shocks, turbulence, and magnetic reconnection. Due to potentially large amplitude of electric fields within these structures, their effects on particle heating, scattering, or acceleration can be important. One possible theoretical description of some of these structures is the concept of Bernstein-Greene-Kruskal (BGK) modes, which are exact nonlinear solutions of the Vlasov-Poisson system of equations in collisionless kinetic theory. BGK modes have been studied extensively for many decades, predominately in one dimension (1D), although there have been observations showing that some of these structures have clear 3D features. While there have been approximate solutions of higher dimensional BGK modes, an exact 3D BGK mode solution in a finite magnetic field has not been found yet. Recently we have constructed exact solutions of 2D BGK modes in a magnetized plasma with finite magnetic field strength in order to gain insights of the ultimate 3D theory [Ng, Bhattacharjee, and Skiff, Phys. Plasmas 13, 055903 (2006)]. Based on the analytic form of these solutions, as well as Particle-in-Cell (PIC) simulations, we will present numerical studies of their stability for different levels of background magnetic field strength.Comment: Submitted to AIP Journal Proceedings for "Tenth Annual International Astrophysics Conference

Light-heavy ion measurements in CR-39 located on the Earth side of LDEF

The azimuthal angle distribution and the charge and energy spectra of selected light-heavy (5 less than or equal to Z less than or equal to 8) stopping particles were measured in a single layer of CR-39 plastic nuclear track detector (PNTD) from the stack of the A0015 experiment located on the Earth-end of the LDEF satellite. The directional incidence of the trapped protons is studied by comparing the azimuthal angle distribution of selected recoils, obtained in the LDEF detectors, to that obtained through calibrations of PNTD's with exposures performed with 200 MeV proton beams from different directions

Some recent observations on small-scale fishery In the vicinity of Madras

Madras zone is one of the important fishing centres on the east coast of India. To understand the fish landings from different gears in Madras, three landing centres, viz., Kasimedu, Triplicane and Nochikuppam were selected. Kasimedu is about 8 km north of Triplicane and Nochikuppam is about 2 km south of Triplicane. The major catch components from the demersal trawls of this area arc silver bellies, threadfin breams, sciaenids, lizardfish, prawns, squids and cuttlefish. These groups are landed in a meagre quantity by the traditional gears, thus maintaining compatability between mechanised and non-mechanised gears in the exploitation of fishery resources off Madras

Towards an Institutional Knowledge Repository (IKR) at IGCAR

The collective acquired information of an organization is called the ‘institutional knowledge’. The centralized Knowledge Repository uses standard taxonomies to consolidate information into one place allowing knowledge to be searched and retrieved with maximum efficiency and accuracy. Many organizations have realized the value of institutional knowledge and already initiated knowledge management systems that collect, store, redistribute, utilize and ultimately leverage the institutional knowledge for the benefit of the organization. All the organizations, in particular the R&D institutions like IGCAR need to build knowledge repository on its specific areas of interest. Once created, the IKR will act as a vehicle for knowledge dissemination, sharing and transfer. This paper gives a comprehensive view on building IKR at IGCAR

User interface design and development: the role of open source systems

Open Source movement has tremendously influenced Information industry, in particular the Digital Library Environment where the Information Systems and services are inevitable. This has helped the Library and Information Centers in developing User Interface to render web based services to the patrons. Wherever the network infrastructure and the target users are in place, the design and development of IR user interface using Open Source system for a specific application is very much possible. This paper highlights the role of Open Source Systems in detail and explains a prototype IR User Interface which was developed in-house at Indira Gandhi Centre for Atomic Research, Kalpakkam

On modular signs

We consider some questions related to the signs of Hecke eigenvalues or Fourier coefficients of classical modular forms. One problem is to determine to what extent those signs, for suitable sets of primes, determine uniquely the modular form, and we give both individual and statistical results. The second problem, which has been considered by a number of authors, is to determine the size, in terms of the conductor and weight, of the first sign-change of Hecke eigenvalues. Here we improve the recent estimate of Iwaniec, Kohnen and Sengupt

On modular signs

We consider some questions related to the signs of Hecke eigenvalues or Fourier coefficients of classical modular forms. One problem is to determine to what extent those signs, for suitable sets of primes, determine uniquely the modular form, and we give both individual and statistical results. The second problem, which has been considered by a number of authors, is to determine the size, in terms of the conductor and weight, of the first sign-change of Hecke eigenvalues. Here we improve significantly the recent estimate of Iwaniec, Kohnen and Sengupta.Comment: 23 pages, 1 figure; new version with new coauthor and strong improvements of two of the two main results

Assessment of the functional outcome of multiple discs prolapses treated with discectomy and surgical stabilization in tertiary care hospital in Salem district

Background:  Low back pain affect up to 80% of people in the modern world at some point in their lives, creating high rates of activity limitation, work absence, impaired quality of life, and the need for medical care. To assess the functional outcome of patients with multiple discs prolapses treated with discectomy and surgical stabilization.Methods: A longitudinal study was conducted in the orthopedics department of Vinayaka missions Kirupananda Variyar medical college, Salem for two years between August 2019 and July 2020. A total of 30 patients presenting with lumbar disc herniation with radiculopathy and neurological deficits were included in the study. The diagnosis was confirmed by doing an X-ray and MRI of the lumbosacral spine. Patients were followed up for 6 months and the nature of the pain was assessed post-operatively using the Japanese orthopedic association system scoring for low back pain. It ranges from 0-15. Score 0 is the worst pain and 15 is normal.Results: The mean Japanese association score for low back pain was 7.2 before the surgical procedure and it was 12 after the procedure and the difference was found to be statistically significant. Among the postoperative complications, 4 patients developed failback syndrome and 1 patient had implant failure.Conclusios: Relief of radicular pain was associated with subjective satisfaction with the surgery among our study population, as evidenced by the decrease in radicular pain and the subjective satisfaction with the operation

Weyl group multiple Dirichlet series constructed from quadratic characters

We construct multiple Dirichlet series in several complex variables whose coefficients involve quadratic residue symbols. The series are shown to have an analytic continuation and satisfy a certain group of functional equations. These are the first examples of an infinite collection of unstable Weyl group multiple Dirichlet series in greater than two variables.Comment: incorporated referee's comment