Signatures of photon and axion-like particle mixing in the gamma-ray burst jet

Photons couple to Axion-Like Particles (ALPs) or more generally to any pseudo Nambu-Goldstone boson in the presence of an external electromagnetic field. Mixing between photons and ALPs in the strong magnetic field of a Gamma-Ray Burst (GRB) jet during the prompt emission phase can leave observable imprints on the gamma-ray polarization and spectrum. Mixing in the intergalactic medium is not expected to modify these signatures for ALP mass > 10^(-14) eV and/or for < nG magnetic field. We show that the depletion of photons due to conversion to ALPs changes the linear degree of polarization from the values predicted by the synchrotron model of gamma ray emission. We also show that when the magnetic field orientation in the propagation region is perpendicular to the field orientation in the production region, the observed synchrotron spectrum becomes steeper than the theoretical prediction and as detected in a sizable fraction of GRB sample. Detection of the correlated polarization and spectral signatures from these steep-spectrum GRBs by gamma-ray polarimeters can be a very powerful probe to discover ALPs. Measurement of gamma-ray polarization from GRBs in general, with high statistics, can also be useful to search for ALPs.Comment: 17 pages, 3 figures. Accepted for publication in JCAP with minor change

Flavor conversion of cosmic neutrinos from hidden jets

High energy cosmic neutrino fluxes can be produced inside relativistic jets under the envelopes of collapsing stars. In the energy range E ~ (0.3 - 1e5) GeV, flavor conversion of these neutrinos is modified by various matter effects inside the star and the Earth. We present a comprehensive (both analytic and numerical) description of the flavor conversion of these neutrinos which includes: (i) oscillations inside jets, (ii) flavor-to-mass state transitions in an envelope, (iii) loss of coherence on the way to observer, and (iv) oscillations of the mass states inside the Earth. We show that conversion has several new features which are not realized in other objects, in particular interference effects ("L- and H- wiggles") induced by the adiabaticity violation. The neutrino-neutrino scattering inside jet and inelastic neutrino interactions in the envelope may produce some additional features at E > 1e4 GeV. We study dependence of the probabilities and flavor ratios in the matter-affected region on angles theta13 and theta23, on the CP-phase delta, as well as on the initial flavor content and density profile of the star. We show that measurements of the energy dependence of the flavor ratios will, in principle, allow to determine independently the neutrino and astrophysical parameters.Comment: 56 pages, 19 figures. Minor changes. Accepted by JHEP

Neutrino Mixing and Neutrino Telescopes

Measuring flux ratios of ultra-high energy neutrinos is an alternative method to determine the neutrino mixing angles and the CP phase delta. We conduct a systematic analysis of the neutrino mixing probabilities and of various flux ratios measurable at neutrino telescopes. The considered cases are neutrinos from pion, neutron and muon-damped sources. Explicit formulae in case of mu-tau symmetry and its special case tri-bimaximal mixing are obtained, and the leading corrections due to non-zero theta_{13} and non-maximal theta_{23} are given. The first order correction is universal as it appears in basically all ratios. We study in detail its dependence on theta_{13}, theta_{23} and the CP phase, finding that the dependence on theta_{23} is strongest. The flavor compositions for the considered neutrino sources are evaluated in terms of this correction. A measurement of a flux ratio is a clean measurement of the universal correction (and therefore of theta_{13}, theta_{23} and delta) if the zeroth order ratio does not depend on theta_{12}. This favors pion sources over the other cases, which in turn are good candidates to probe theta_{12}. The only situations in which the universal correction does not appear are certain ratios in case of a neutron and muon-damped source, which depend mainly on theta_{12} and receive only quadratic corrections from the other parameters. We further show that there are only two independent neutrino oscillation probabilities, give the allowed ranges of the considered flux ratios and of all probabilities, and show that none of the latter can be zero or one.Comment: 29 pages, 8 figures. Minor changes, to appear in JCA

A review on activated carbon: process, application and prospects

Activated carbon (AC) is used in different states of applications after its discovery as a strong and reliable adsorbent. An overview on AC is presented together with revisiting the sources of AC generation; methods used to generate AC comprising of pyrolysis activation; physical activation; chemical activation and steam pyrolysis. The important factors affecting the AC production, the possible applications of AC and their future prospects are also discussed. AC is applied in water, wastewater and leachate treatments in many countries, especially to polish the color, remove the odor and some heavy metals. It is cheap and available, and can be produced from agricultural waste materials, e.g. rice husk, palm oil shell and coconut shell. The AC’s fine and porous structure and an extremely large particle surface area (>1000 m2/g) results in making it possessed powerful adsorptive properties. Therefore, the adsorption process using AC is found to be a potentially viable method of removing pollutants from aqueous solutions

Hints of an axion-like particle mixing in the GeV gamma-ray blazar data?

Axion-Like Particles (ALPs), if exist in nature, are expected to mix with photons in the presence of an external magnetic field. The energy range of photons which undergo strong mixing with ALPs depends on the ALP mass, on its coupling with photons as well as on the external magnetic field and particle density configurations. Recent observations of blazars by the Fermi Gamma-Ray Space Telescope in the 0.1-300 GeV energy range show a break in their spectra in the 1-10 GeV range. We have modeled this spectral feature for the flat-spectrum radio quasar 3C454.3 during its November 2010 outburst, assuming that a significant fraction of the gamma rays convert to ALPs in the large scale jet of this blazar. Using theoretically motivated models for the magnetic field and particle density con figurations in the kiloparsec scale jet, outside the broad-line region, we find an ALP mass m(a) similar to (1 ¿ 3).10(-7) eV and coupling g(a gamma) similar to (1 ¿ 3).10(-10) GeV-1 after performing an illustrative statistical analysis of spectral data in four different epochs of emission. The precise values of m(a) and g(a gamma) depend weakly on the assumed particle density con figuration and are consistent with the current experimental bounds on these quantities. We apply this method and ALP parameters found from fitting 3C454.3 data to another flat-spectrum radio quasar PKS1222+216 (4C+21.35) data up to 400 GeV, as a consistency check, and found good fit. We find that the ALP-photon mixing effect on the GeV spectra may not be washed out for any reasonable estimate of the magnetic field in the intergalactic media

Changes in inequality of childhood morbidity in Bangladesh 1993-2014: a decomposition analysis

Introduction: Child health remains an important public health concern at the global level, with preventable diseases such as diarrheal disease, acute respiratory infection (ARI) and fever posing a large public health burden in low- and middle-income countries including Bangladesh. Improvements in socio-economic conditions have tended to benefit advantaged groups in societies, which has resulted in widespread inequalities in health outcomes. This study examined how socioeconomic inequality is associated with childhood morbidity in Bangladesh, and identified the factors affecting three illnesses: diarrhea, ARI and fever. Materials and methods: A total of 43,860 sample observations from the Bangladesh Demographic and Health Survey, spanning a 22-year period (1993–2014), were analysed. Concentration curve and concentration index methods were used to evaluate changes in the degree of household wealth-related inequalities and related trends in childhood morbidity. Regression-based decomposition analyses were used to attribute the inequality disparities to individual determinants for the three selected causes of childhood morbidity. Results: The overall magnitude of inequality in relation to childhood morbidity has been declining slowly over the 22-year period. The magnitude of socio-economic inequality as a cause of childhood morbidity varied during the period. Decomposition analyses attributed the inequalities to poor maternal education attainment, inadequate pre-delivery care, adverse chronic undernutrition status and low immunisation coverage. Conclusions: High rates of childhood morbidity were observed, although these have declined over time. Socio-economic inequality is strongly associated with childhood morbidity. Socio-economically disadvantaged communities need to be assisted and interventions should emphasise improvements of, and easier access to, health care services. These will be key to improving the health status of children in Bangladesh and should reduce economic inequality through improved health over time

Social factors and overweight: evidence from nine Asian INDEPTH Network sites

Background: Overweight/obesity increases the risk of morbidity and mortality from a number of chronic conditions, including heart disease, stroke, diabetes and some cancers. This study examined the distribution of body mass index (BMI) in nine Health and Demographic Surveillance System (HDSS) sites in five Asian countries and investigated the association between social factors and overweight. Data and methods: This cross-sectional study was conducted in nine HDSS sites in Bangladesh, India, Indonesia, Thailand and Vietnam. The methodology of the WHO STEPwise approach to Surveillance with core risk factors (Step 1) and physical measurements for weight, height and waist circumference (Step 2) were included. In each site, about 2,000 men and women aged 25Á64 years were selected randomly using the HDSS database. Weight was measured using electronic scales, height was measured by portable stadiometers and waist circumference was measured by measuring tape. Overweight/obesity was assessed by BMI defined as the weight in kilograms divided by the square of the height in metres (kg/

The Gamma Ray Burst section of the White Paper on the Status and Future of Very High Energy Gamma Ray Astronomy: A Brief Preliminary Report

Original paper can be found at: http://proceedings.aip.org/proceedings/ Copyright American Institute of Physics DOI: 10.1063/1.2943545otherPeer reviewe

Agricultural livelihoods in coastal Bangladesh under climate and environmental change - A model framework

We describe a novel integrated modelling system aiming to approximate the impact of environmental change on farmers' livelihoods in Bangladesh.</p

Multimodal freight transportation: sustainability challenges

Due to globalization in trade, the development of multimodal cargo shipments and the related transport needs have created a range of challenges. Interestingly, sustainability of multimodal freight transportation is still subject to minor consideration, on the grounds that economic interests are frequently positioned much higher than social or environmental objectives. This proposed research plan is needed to assess whether and to what extent the multimodal freight system is achieving the results in the sustainability dimensions: economic, social and environmental. Thus, it will carry out a critical appraisal of the multimodal freight transportation sector to provide an up-to-date knowledge on the sustainability challenges and the potential solutions through doctoral research. This paper structured to present a review of existing literature on freight transportation and multimodal freight transport highlighting the sustainability concerns with multimodal freight transport systems. It also highlights the gaps in knowledge with a justification on the need to address these gaps for the system to function optimally. It also covers the methodology that would be applied and the sources of data that would be reviewed to ensure the aim and objectives are clearly addressed. The paper concludes by discussing the significance of the expected findings in the light of sustainability in multimodal freight transport to the academia, policy makers and the freight transportation industry