Light Dark Matter in a Blazar-heated Universe

Prompt emissions from TeV blazars pair produce off the extragalactic background light and the highly energetic resulting pair beams then cascade through inverse Compton scattering to give rise to secondary gamma-rays. Such reprocessed cascade emission that can be associated with individual blazar sources has not been detected thus far. The absence of pair halos around these sources, along with the non-observation of isotropic gamma-ray background excess, seems to suggest that collective plasma effects, such as beam-plasma instabilities, can play a crucial role in alleviating this GeV-TeV tension by transferring the energy from the pair beams into the background plasma of the intergalactic medium (IGM). This has profound implications not only for TeV astrophysics, but also the strength of the intergalactic magnetic field and properties of dark matter (DM). A direct consequence of the instability losses and IGM heating is the modification of thermal history at late times, which suppresses structure formation particularly in baryonically underdense regions, potentially holding a clue towards resolving the small-scale crisis in cosmology. In a blazar-heated universe, the observation of dwarf galaxies and Lyman-$\alpha$ measurements present a favoured mass range for DM candidates such as light axion-like particles.Comment: Proceedings for the 38th International Cosmic Ray Conference (ICRC2023

Lab-on-chip projection system for fluorescence based medical analysis

The aim of this research project is to implement a novel concept of using a scanning projection system for exciting fluorescence in lab-on-chip devices. While scanning projectors are state of the art in display applications, this use case imposes a set of specific requirements not fulfilled by commercial devices. One advantage in the lab-on-chip setting is increased flexibility in the design of disposables. To implement the final goal, the theoretical feasibility of the optical system is estimated, followed by simulation of the entire setup in Zemax OpticStudio and finally building up the working prototype of the projection system in the lab as a proof of concept, to compare the experimental findings with the simulation results

Lab-on-chip projection system for fluorescence based medical analysis

The aim of this research project is to implement a novel concept of using a scanning projection system for exciting fluorescence in lab-on-chip devices. While scanning projectors are state of the art in display applications, this use case imposes a set of specific requirements not fulfilled by commercial devices. One advantage in the lab-on-chip setting is increased flexibility in the design of disposables. To implement the final goal, the theoretical feasibility of the optical system is estimated, followed by simulation of the entire setup in Zemax OpticStudio and finally building up the working prototype of the projection system in the lab as a proof of concept, to compare the experimental findings with the simulation results

Evolution of Relativistic Pair Beams: Implications for Laboratory and TeV Astrophysics

Missing cascades from TeV blazar beams indicate that collective plasma effects may play a significant role in their energy loss. It is possible to mimic the evolution of such highly energetic pair beams in laboratory experiments using modern accelerators. The fate of the beam is governed by two different processes, energy loss through the unstable mode and energetic broadening of the pair beam through diffusion in momentum space. We chalk out this evolution using a Fokker-Planck approach in which the drift and the diffusion terms respectively describe these phenomena in a compact form. We present particle-in-cell simulations to trace the complete evolution of the unstable beam-plasma system for a generic narrow Gaussian pair beam for which the growth rate is reactive. We show that the instability leads to an energetic broadening of the pair beam, slowing down the instability growth in the linear phase, in line with the analytical and numerical solutions of the Fokker-Planck equation. Whereas in a laboratory experiment the change in the momentum distribution is an easily measured observable as a feedback of the instability, the consequence of diffusive broadening in an astrophysical scenario can be translated to an increase in the opening angle of the pair beam.Comment: 20 pages, 10 figure

Third EuCAPT Annual Symposium

TeV blazars dominate the extragalactic gamma-ray sky and highly energetic pair beams arising from such blazar jets underproduce gamma rays in the GeV band while inverse-Compton scattering off the cosmic microwave background. Recent Fermi-LAT isotropic gamma-ray background measurements suggest that space plasma instabilities can play a crucial role in alleviating this GeV-TeV tension by transferring energy from the active galactic nucleus into the intergalactic medium. A direct consequence of such instability losses is the modification of thermal history and suppression of power at late times, potentially holding a clue towards resolving the small-scale crisis in cosmology. We show that the observation of dwarf galaxies and Lyman-alpha measurements can narrow down the mass range for light axion-like particles in a blazar-heated universe

Biochemical and clinical variations among severe Plasmodium Vivax malaria cases: A prospective study

Context: Plasmodium vivax is geographically widely distributed with up to 2.5 billion people at risk and an estimated 70-80 million cases every year. India contributes 77% of the total malaria in Southeast Asia. Retrospective analysis of burden of malaria showed that disability adjusted life years due to malaria were 1.86 million years. According to recent study, West Bengal contributes 11% of total malaria cases in country and is one of states where falciparum resistance to chloroquine has been confirmed. Aims: The aim of this study was to evaluate the biochemical and clinical profile of severe and non-severe Plasmodium vivax malaria and the complications and outcome of P. vivax malaria infections as there is very limited information on age and sex specific seasonal prevalence of malaria in different paradigms in the country. Materials and Methods: A hospital based prospective study was conducted in Medical College, Kolkata comprising of 138 patients with fever (≥37.5˚C), peripheral smear and/or rapid diagnostic tests positive for P. vivax. Previously established cases of CKD, hematological abnormalities, chronic liver diseases and neuro-psychiatric disorders were excluded from our study. Demographical, clinical and laboratory parameters including liver function test, renal function test were documented and were presented in tabular and statistical means. Results: Jaundice was present in 22% of patients and vomiting in 32% of the patients. Hepatomegaly was seen in 16 % cases and 33% cases had splenomegaly. ARDS was seen in 16% of severe malaria cases. Acute kidney injury was seen in 8% and cerebral malaria was seen in 12% of severe malaria cases. Multi organ dysfunction was seen in12 %cases. There was 1 death in the study due to multi organ dysfunction. Conclusion: Life threatening complications such as ARDS, AKI, cerebral malaria and MODS can be seen in P. vivax mono infections