Leptogenesis in an extended seesaw model with U(1)B−LU(1)_{B-L} symmetry

We have explored an extended seesaw model accommodating a keV sterile neutrino adopting $U(1)_{B-L}$ symmetry. This model provides a natural platform for achieving resonant leptogenesis to account for the observed baryon asymmetry of the Universe. The required lepton asymmetry is sourced by the CP violating decay of the lightest heavy right handed neutrino to Standard Model leptons and Higgs. The presence of the light sterile neutrino in the model brings out an enhancement in the final lepton asymmetry through an additional self-energy contribution. Adopting a proper treatment for all the washout processes this framework strictly favours a strong washout regime thereby protecting the low energy neutrino mass parameters in agreement with the present neutrino and cosmology data. This framework of extended seesaw scheme offers the source of matter-antimatter asymmetry without any severe fine tuning of the Yukawa couplings governing the tiny neutrino mass. We also comment on the half-life period for the neutrino less double beta decay process in the background of having a keV sterile neutrino satisfying all the constraints which guide the explanation for the observed baryon asymmetry of the Universe.Comment: Explanations added in some places, conclusion remains unchange

Emergent Universe with Exotic Matter in Brane World Scenario

In this work, we have examined the emergent scenario in brane world model for phantom and tachyonic matter. For tachyonic matter field we have obtained emergent scenario is possible for closed, open and at model of the universe with some restriction of potential. For normal scalar field the emergent scenario is possible only for closed model and the result is identical with the work of Ellis et al [2], but for phantom field the emergent scenario is possible for closed, open and at model of the universe with some restriction of potential

Higher Dimensional Cosmology with Some Dark Energy Models in Emergent, Logamediate and Intermediate Scenarios of the Universe

We have considered N-dimensional Einstein field equations in which four-dimensional space-time is described by a FRW metric and that of extra dimensions by an Euclidean metric. We have chosen the exponential forms of scale factors a and d numbers of b in such a way that there is no singularity for evolution of the higher dimensional Universe. We have supposed that the Universe is filled with K-essence, Tachyonic, Normal Scalar Field and DBI-essence. Here we have found the nature of potential of different scalar field and graphically analyzed the potentials and the fields for three scenario namely Emergent Scenario, Logamediate Scenario and Intermediate Scenario. Also graphically we have depicted the geometrical parameters named statefinder parameters and slow-roll parameters in the higher dimensional cosmology with the above mentioned scenarios.Comment: 21 pages, 36 figure

Fractional Action Cosmology: Emergent, Logamediate, Intermediate, Power law Scenarios of the Universe and Generalized Second Law of Thermodynamics

In the framework of Fractional Action Cosmology (FAC), we study the generalized second law of thermodynamics for the Friedmann Universe enclosed by a boundary. We use the four well-known cosmic horizons as boundaries namely, apparent horizon, future event horizon, Hubble horizon and particle horizon. We construct the generalized second law (GSL) using and without using the first law of thermodynamics. To check the validity of GSL, we express the law in the form of four different scale factors namely emergent, logamediate, intermediate and power law. For Hubble, apparent and particle horizons, the GSL holds for emergent and logamediate expansions of the universe when we apply with and without using first law. For intermediate scenario, the GSL is valid for Hubble, apparent, particle horizons when we apply with and without first law. Also for intermediate scenario, the GSL is valid for event horizon when we apply first law but it breaks down without using first law. But for power law expansion, the GSL may be valid for some cases and breaks down otherwise.Comment: 24 pages, 32 figures, Accepted in Int. J. Theor. Phy

Isolation of an unusual metabolite 2-allyloxyphenol from a marine actinobacterium, its biological activities and applications

A marine actinobacterium isolated from the Bay of Bengal, India and previously found to be producing an antimicrobial and cytotoxic terpenoid was further investigated for antimicrobial metabolites. The bacterium was preliminarily identified as a new species of the genus Streptomyces (strain MS1/7). The cell-free culture broth was extracted with n-butanol and purified using silica gel column chromatography and high-performance liquid chromatography. Molecular characterization was done using ESI mass, IR and 1H and 13C NMR spectrometry. 2-Allyloxyphenol (MW 150; C9H10O2), a synthetic drug and chemical intermediate, was obtained as a natural product for the first time. Serendipitous natural occurrence provided new insights into the synthetic molecule. 2-Allyloxyphenol was found to be inhibitory to 21 bacteria and three fungi in the minimum range 0.2–1.75 mg mL−1 determined by agar dilution method. 2-Allyoxyphenol possesses strong antioxidant property (IC50 22 μg mL−1, measured by 1, 1-diphenyl-2-picryl hydrazyl scavenging activity). Hydroxyl and allyloxy groups in 2-allyloxyphenol were responsible for antimicrobial and antioxidant activities. 2-Allyloxyphenol has marked resemblance to smoky aroma and is two to three times more active as an antimicrobial than some commercial smoke-flavour compounds. Absence of hemolytic toxicity, potential carcinogenicity, cytotoxicity and reports of toxic reactions in literature suggest possible application of 2-allyloxyphenol as a food preservative and an oral disinfectant. Keywords Sundarbans . 2-Allyloxyphenol . Streptomyces . Antimicrobial . Antioxidant . Smoke flavou

Management of Postoperative Hypoxaemia in Patients Following Upper Abdominal Laparoscopic Surgery. - A Comparative Study

Noninvasive ventilation has been shown to reduce acute postoperative hypoxaemia, with significant reduction in the incidence of re-intubation, complications and a trend towards lower mortality. The aim of the study was to determine the effectiveness of CPAP vs venturi therapy in early achievement of oxygenation goals and in prevention of re-intubation for management of postoperative hypoxaemia following laparoscopic cholecystectomy. Forty adult patients of ASA physical status I& II, scheduled for elective laparoscopic cholecystectomy, those were unable to maintain SpO2 > 95% breathing room air after extubation, were recruited for a prospective, randomized comparative study. Patients with PaO2 / FiO2 between 250 and 300 were included in the study and were randomly allocated to one of the two groups to receive oxygen therapy either using a CPAP of 10 cm of water and a FiO2 of 0.5 (Group A) or using a venturi mask of FiO2 of 0.5 (Group B) . All patients were observed postoperatively upto 18 h and were screened by ABG analyses at 6, 12 and 18 h of treatment. SpO2, ECG, heart rate, respiratory rate, temperature and NIBP were monitored throughout the study period. Patients in Group A showed significant improvement in early achievement of adequate oxygenation than those in Group B, although, due to intolerance to CPAP therapy two patients in Group A needed reintubation to maintain adequate oxygenation. To conclude, oxygenation using continuous positive airway pressure is a safe and effective means in improving gas exchange to treat acute postoperative hypoxaemia in conscious and cooperative patients

COVID-19 test-to-stay program for K-12 schools: Opt-in versus opt-out consent model

Summary: The Centers for Disease Control and Prevention promoted the Test-to-Stay (TTS) program to facilitate in-person instruction in K-12 schools during COVID-19. This program delineates guidelines for schools to regularly test students and staff to minimize risks of infection transmission. TTS enrollment can be implemented via two different consent models: opt-in, in which students do not test regularly by default, and the opposite, opt-out model. We study the impacts of the two enrollment approaches on testing and positivity rates with data from 259 schools in Illinois. Our results indicate that after controlling for other covariates, schools following the opt-out model are associated with 84% higher testing rate and 30% lower positivity rate. If all schools adopted the opt-out model, 20% of the total lost school days could have been saved. The lower positivity rate among the opt-out group is largely explained by the higher testing rate in these schools, a manifestation of status quo bias