Accretion onto a noncommutative geometry inspired black hole

The spherically symmetric accretion onto a noncommutative (NC) inspired Schwarzschild black hole is treated for a polytropic fluid. The critical accretion rate $\dot{M}$, sonic speed $a_s$ and other flow parameters are generalised for the NC inspired black hole and compared with the results obtained for the standard Schwarzschild black holes. We also derive explicit expressions for gas compression ratios and temperature profiles below the accretion radius and at the event horizon. This analysis is a generalisation of Michel's solution to the NC geometry. Owing to the NC corrected black hole, the accretion flow parameters have also been modified. It turns out that $\dot{M} \approx {M^2}$ is still achievable but $r_s$ seems to be substantially decreased due to NC effects, that in turn does affect the accretion process.Comment: Published in EPJ

Rotating black hole in Rastall theory

Rotating black hole solutions in theories of modified gravity are important as they offer an arena to test these theories through astrophysical observation. The non-rotating black hole can be hardly tested since the black hole spin is very important in any astrophysical process. We present rotating counterpart of a recently obtained spherically symmetric exact black hole solution surrounded by perfect fluid in the context of Rastall theory, viz, rotating Rastall black hole that generalize the Kerr-Newman black hole solution. In turn, we analyze the specific cases of the Kerr-Newman black holes surrounded by matter like dust and quintessence fields. Interestingly, for a set of parameters and a chosen surrounding field, there exists a critical rotation parameter ($a=a_{E}$), which corresponds to an extremal black hole with degenerate horizons, while for $a<a_{E}$, it describes a non-extremal black hole with Cauchy and event horizons, and no black hole for $a>a_{E}$ with value $a_E$ is also influenced by these parameters. We also discuss the thermodynamical quantities associated with rotating Rastall black hole, and analyze the particle motion with the behavior of effective potential.Comment: 26 pages, 8 figures. Matched with the published versio

A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (ν\nu) and μ\mu-DAR (νˉ\bar{\nu})

Neutrino mass hierarchy, CP-violation, and octant of $\theta_{23}$ are the fundamental unknowns in neutrino oscillations. In order to address all these three unknowns, we study the physics reach of a setup, where we replace the antineutrino run of T2HK with antineutrinos from muon decay at rest ($\mu$-DAR). This approach has the advantages of having higher statistics in both neutrino and antineutrino modes, and lower beam-on backgrounds for antineutrino run with reduced systematics. We find that a hybrid setup consisting of T2HK ($\nu$) and $\mu$-DAR ($\bar\nu$) in conjunction with full exposure from T2K and NO$\nu$A can resolve the issue of mass hierarchy at greater than 3$\sigma$ C.L. irrespective of the choices of hierarchy, $\delta_{\mathrm{CP}}$, and $\theta_{23}$. This hybrid setup can also establish the CP-violation at 5$\sigma$ C.L. for $\sim$ 55% choices of $\delta_{\mathrm{CP}}$, whereas the same for conventional T2HK ($\nu + \bar\nu$) setup along with T2K and NO$\nu$A is around 30%. As far as the octant of $\theta_{23}$ is concerned, this hybrid setup can exclude the wrong octant at 5$\sigma$ C.L. if $\theta_{23}$ is at least $3^{\circ}$ away from maximal mixing for any $\delta_{\mathrm{CP}}$.Comment: 18 pages, 28 pdf figures, 1 table. Minor changes in the text. A new footnote added. Accepted in JHE

Assessing and Mapping Vulnerability and Risk Perceptions to Groundwater Arsenic Contamination : Towards Developing Sustainable Arsenic Mitigation Models

This study focuses on the arsenic-affected rural communities in Bihar located within the mid-Gangetic Plain in India. A random stratified sampling method is applied to survey 340 households in three villages (Suarmarwa, Rampur Diara, and Bhawani Tola), through a structured questionnaire. A reliable arsenic field testing kit is used to analyze the drinking water sources in the field, followed by a confirmatory test of a subset of water samples through Atomic Absorption Spectrophotometry. The study has two major goals: 1) Develop sustainable arsenic-mitigation models; and 2) Create a “composite vulnerability index,” and present the information as a map for use in targeting of areas for intervention and policy-making. Arsenic levels exceeding the World Health Organization and the Bureau of Indian Standards (max=300μg/L) were observed in all three villages. The hazard quotient and cancer risks for children in all three villages were high and very high, respectively. Arsenic treatment units and piped water supply systems were the most preferred sustainable arsenic-mitigation options in the surveyed villages, followed by deep tube wells, dug-wells, and rainwater harvesting systems. Arsenic awareness, willingness to pay for arsenic-free water, trust in agencies, trust in institution, and social capital were found to be the most significant factors for decision-making to prefer one arsenic-mitigation technology to others. The surveyed respondents perceive health and economic risks more so than social discrimination risks with regard to arsenic-contaminated groundwater, and were more willing to adopt arsenic-mitigation technologies. The strongest predictors of health-risk perception were caste, education, agricultural-landholdings, housing status, and social capital. Predictors of economic-risk perception were caste, education, income, sanitation practices, people’s prioritization of socio-environmental problems, arsenic awareness, social capital, institutional trust, and social trust. Predictors of social discrimination risk were agricultural landholdings, people’s prioritization of social problems, arsenic awareness, institutional trust, and social capital. Katihar in Bihar, with the least adaptive capacity and high vulnerability to arsenic contamination, should be prioritized in arsenic-mitigation policies. With a high level of adaptive capacity in Bhojpur district, the likelihood of success of arsenic-mitigation technology is the highest. A program utilizing expensive arsenicmitigation technologies will not work in the Vaishali, Samastipur, Khagaria, and Purnia districts

DD-dimensional Bardeen-AdS black holes in Einstein-Gauss-Bonnet theory

We present a $D$-dimensional Bardeen like Anti-de Sitter (AdS) black hole solution in Einstein-Gauss-Bonnet (EGB) gravity, \textit{viz}., Bardeen-EGB-AdS black holes. The Bardeen-EGB-AdS black hole has an additional parameter due to charge ($e$), apart from mass ($M$) and Gauss-Bonnet parameter ($\alpha$). Interestingly, for each value of $\alpha$, there exist a critical $e = e_E$ which corresponds to an extremal regular black hole with degenerate horizons, while for $e< e_E$, it describes non-extremal black hole with two horizons. Despite the complicated solution, the thermodynamical quantities, like temperature ($T$), specific heat($C$) and entropy ($S$) associated with the black hole are obtained exactly. It turns out that the heat capacity diverges at critical horizon radius $r_+ = r_C$, where the temperature attains maximum value and the Hawking-Page transition is achievable. Thus, we have an exact $D$-dimensional regular black holes, when evaporates lead to a thermodynamical stable remnant.Comment: 25 pages, 48 figure

To determine the role of targeted four node sampling (FNS) in axillary mapping in operable breast cancer

Aim: to determine the role of targeted four node sampling (FNS) in axillary mapping in operable breast cancer. Methods: The present analytical hospital based study was conducted among histopathologically and cytologically confirmed patients of operable breast cancer admitted to inpatient department of General Surgery, Sri Krishna Medical College and Hospital, Muzaffarpur, India July 2019 to February 2020. A total of 30 patients, node negative operable cases of carcinoma breast after 3 cycles of neoadjuvant chemotherapy, were enrolled. Lymph node mapping was done by injecting 3 - 5 ml of methylene blue dye, just before surgery. Results: The sensitivity, specificity, positive predictive value and negative predictive value of 83.12%, 90.27%, 72.31% and 94.25% respectively for four node sampling of axilla, among operable breast cancer patients having node negative axilla. Conclusions: Targeted four node sampling using methylene blue dye can be considered as an alternative method for sentinel lymph node. Further study should be conducted to establish it as a reliable method for axillary lymph node staging