Genericity aspects in gravitational collapse to black holes and naked singularities

We investigate here the genericity and stability aspects for naked singularities and black holes that arise as the final states for a complete gravitational collapse of a spherical massive matter cloud. The form of the matter considered is a general Type I matter field, which includes most of the physically reasonable matter fields such as dust, perfect fluids and such other physically interesting forms of matter widely used in gravitation theory. We first study here in some detail the effects of small pressure perturbations in an otherwise pressure-free collapse scenario, and examine how a collapse evolution that was going to the black hole endstate would be modified and go to a naked singularity, once small pressures are introduced in the initial data. This allows us to understand the distribution of black holes and naked singularities in the initial data space. Collapse is examined in terms of the evolutions allowed by Einstein equations, under suitable physical conditions and as evolving from a regular initial data. We then show that both black holes and naked singularities are generic outcomes of a complete collapse, when genericity is defined in a suitable sense in an appropriate spac

Giant magnetoelectric effect in pure manganite-manganite heterostructures

Obtaining strong magnetoelectric couplings in bulk materials and heterostructures is an ongoing challenge. We demonstrate that manganite heterostructures of the form ${\rm (Insulator)/(LaMnO_3)_n/(CaMnO_3)_n/(Insulator)}$ show strong multiferroicity in magnetic manganites where ferroelectric polarization is realized by charges leaking from ${\rm LaMnO_3}$ to ${\rm CaMnO_3}$ due to repulsion. Here, an effective nearest-neighbor electron-electron (electron-hole) repulsion (attraction) is generated by cooperative electron-phonon interaction. Double exchange, when a particle virtually hops to its unoccupied neighboring site and back, produces magnetic polarons that polarize antiferromagnetic regions. Thus a striking giant magnetoelectric effect ensues when an external electrical field enhances the electron leakage across the interface.Comment: 13 page

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RdRp (RNA-dependent RNA polymerase): A key target providing anti-virals for the management of various viral diseases

With the arrival of the Covid-19 pandemic, anti-viral agents have regained center stage in the arena of medicine. Out of the various drug targets involved in managing RNA-viral infections, the one that dominates almost all RNA viruses is RdRp (RNA-dependent RNA polymerase). RdRp are proteins that are involved in the replication of RNA-based viruses. Inhibition of RdRps has been an integral approach for managing various viral infections such as dengue, influenza, HCV (Hepatitis), BVDV, etc. Inhibition of the coronavirus RdRp is currently rigorously explored for the treatment of Covid-19 related complications. So, keeping in view the importance and current relevance of this drug target, we have discussed the importance of RdRp in developing anti-viral agents against various viral diseases. Different reported inhibitors have also been discussed, and emphasis has been laid on highlighting the inhibitor's pharmacophoric features and SAR profile. (c) 2021 Elsevier B.V. All rights reserved

The Application of Nanotechnology and Nanomaterials in Depression: An Updated Review

Depression is the most common stress-related mental illness. It has an impact on millions of individuals globally. Genetic, biochemical, environmental, and psychological elements can all play a role in its development. Medications, psychotherapy, and lifestyle changes are frequently used to treat depression. Antidepressant medications work by altering the levels of certain chem-icals in the brain. At the same time, psychotherapy aims to help individuals better understand and manage their emotions and thoughts, which otherwise may lead to depression. The current treatment strategy for the illness has several drawbacks, such as adverse effects, ineffectiveness, long-term use, stigma, and cost-related issues of the medication used. These negative effects un-derscore the need for more successful and novel methods of treating depression, such as the investigation of medication delivery techniques based on nanotechnology. Increased medication effectiveness, fewer side effects, long-lasting medication effects, a good understanding of the neural underpinnings of depression, and the potential for the creation of personalized medicines are some of the potential benefits of using nanotechnology in depressive disorder treatment. In several scientific domains, nanotechnology has many benefits. Nanoparticles are the fundamen-tal building blocks of nanotechnology in this regard. Nanoparticles hold great promise for use in medical applications, as recently developed nanotechnology has shown. This review focuses on the most popular nanomaterials that are used to treat depression, in addition to how well these nanomaterials are at managing depression based on their physical, chemical, and biological properties. We have also talked about the difficulties that the various nanomaterials face, which limit their uses and prevent the development of effective clinical therapies