No abstract

A travelling wave solution is presented for relativistic upper-hybrid oscillations (RUHOs) in a cold magnetized plasma. An expression for the wave-breaking amplitudes of RUHOs is derived. The wave-breaking amplitudes of RUHOs are found to decrease with the increase of the strength of an ambient magnetic field. These results will be of relevance to the laboratory context of particle acceleration by wake-fields in which magnetic field plays a central role.

The construction of paleo-climatic calendar based on various evidences as well as instrumental records of climatic elements tell that climate has changed to a great extent over time. Scientific evidences establish the fact that the impacts of climate change are having wide immediate as well as long-term indirect effects on public health. Especially the focus is on climate change impacts in terms of increased severity, frequency and spread of vector-borne diseases. Climate changes in terms of increased average temperatures, more intense rainfall, extended summer season and less intense winters can impact the range and incidence of infectious and vector-borne diseases. Odisha, an eastern coastal state of India, is not an exception in experiencing the effects of climate change in spreading of vectorborne diseases. Malaria is one of the most important and widely distributed vector-borne disease observed in Odisha. Transmission of malaria is a dynamic process influenced by the changes in ecological and meteorological conditions. The other vector-borne diseases observed in Odisha since last decade include dengue, Japanese encephalitis and chikungunya. The mid-June period is usually characterized by onset of South West monsoon in Odisha in past. However, the analysis indicates an increase in number of heat wave days in the month of June in recent years, which may be an indicator of gradual shift of monsoon season in Odisha. The results also indicate that vector-borne disease conducive season extends from July till November, nearly half of the year. Further, the dengue and chikungunya are more prevalent in coastal districts, whereas malaria and JE have been experienced in interior districts.

Phase-mixing of large amplitude non-relativistic electron oscillations around an inhomogeneous background of massive ions has been studied in a cold plasma. For our purpose, a space periodic but time independent ion density profile along with a perturbation in the electron density is considered. An exact space-time dependent solution is presented in the parametric form by using Lagrangian coordinates. An inhomogeneity in the ion density causes the characteristic plasma frequency to acquire spatial dependency, leading to phase-mixing and thus breaking of excited oscillations at arbitrary amplitudes. The effects of finite amplitude electron density perturbation on the process of phase-mixing have also been discussed.