Multi-epoch intra-night optical monitoring of 8 radio-quiet BL Lac candidates

For a new sample of 8 weak-line-quasars (WLQs) we report a sensitive search in 20 intranight monitoring sessions, for blazar-like optical flux variations on hour-like and longer time scale (day/month/year$-$like). The sample consists exclusively of the WLQs that are not radio$-$loud and have either been classified as `radio-weak probable BL Lac candidates' and/or are known to have exhibited at least one episode of large, blazar$-$like optical variability. Whereas only a hint of intra$-$night variability is seen for two of these WLQs, J104833.5$+$620305.0(z = 0.219) and J133219.6$+$622715.9 (z = 3.15), statistically significant inter$-$night variability at a few per cent level is detected for three of the sources, including the radio-intermediate WLQ J133219.6$+$622715.9 (z = 3.15) and the well known bona$-$fide radio$-$quiet WLQs J121221.5$+$534128.0 (z = 3.10) and WLQ J153259.9$-$003944.1 (z = 4.62). In the rest$-$frame, this variability is intra-day and in the far$-$UV band. On the time scale of a decade, we find for three of the WLQs large brightness changes, amounting to 1.655$\pm$0.009, 0.163$\pm$0.010 and 0.144$\pm$0.018 mag, for J104833.5$+$620305.0, J123743.1$+$630144.9 and J232428.4$+$144324.4, respectively. Whereas the latter two are confirmed radio-quiet WLQs, the extragalactic nature of J104833.5$+$620305.0 remains to be well established, thanks to the absence of any feature(s) in its available optical spectra. The present study forms a part of our ongoing campaign of intranight optical monitoring of radio quiet weak-line quasars, in order to improve the understanding of this enigmatic class of Active Galactic Nuclei and to look among them for a possible tiny, elusive population of radio-quiet BL Lacs.Comment: Accepted to MNRAS. 12 pages, 1 figure, 4 Tabl

Enhanced Removal Efficiency of Arsenic and Copper from Aqueous Solution Using Activated Acorus calamus Based Adsorbent

Water security, due to heavy metal pollution in water resources, has become a serious problem in modern urbanized society. Plants with a good source of cellulose, hemicellulose, pectin, lignin, etc., are the most promising adsorbents for the removal of heavy metals from water. In this work, for the first time, a low-cost local plant named Acorus calamus (AC; flag root or sweet flag) and citric acid modified AC root powder (CAMAC) were used as potential adsorbents. The samples were characterized by SEM, FT-IR, XRD, and the sorption properties were investigated by different parameters, such as solution pH, batch kinetic study, batch isotherm, effect of adsorbent dose, effect of initial concentration, and effect of contact time. The results of ACRP on removal efficiency of copper (II) and arsenic (III) in an aqueous solution showed an excellent adsorption behavior (~ 80 % adsorption efficiency). This study opens up an easy and economical method for the decontamination of harsh polluting metal ions from water. This work is licensed under a Creative Commons Attribution 4.0 International License

Optimisation of abrasive wear of rice husk reinforced epoxy composite by using response surface methodology

Wear is the disintegration or sideways uprooting of a material from its "derivative" and unique position on a solid surface performed by the movement of an alternate surface. The requirement for relative movement between two surfaces and mechanical contact between asperities is a paramount refinement between mechanical wear contrasted with different courses of action with comparative results. The wear analysis is possible by expository procedures like Response Surface Methodology. Response Surface Methodology (RSM) is an accumulation of statistical and mathematical techniques helpful for creating, enhancing, and upgrading methodologies. It additionally has important requisitions in the outline, advancement, and definition of new items, and also in the change of existing item plans. The broadest provisions of RSM are in the modern world, especially in circumstances where several input variables conceivably impact some performance measure or quality characteristic of the product or process

Limits on the time variation of the electromagnetic fine-structure constant in the low energy limit from absorption lines in the spectra of distant quasars

Most of the successful physical theories rely on the constancy of few fundamental quantities (such as the speed of light, $c$, the fine-structure constant, \alpha, the proton to electron mass ratio, \mu, etc), and constraining the possible time variations of these fundamental quantities is an important step toward a complete physical theory. Time variation of \alpha can be accurately probed using absorption lines seen in the spectra of distant quasars. Here, we present the results of a detailed many-multiplet analysis performed on a new sample of Mg II systems observed in high quality quasar spectra obtained using the Very Large Telescope. The weighted mean value of the variation in \alpha derived from our analysis over the redshift range 0.4<z<2.3 is \Delta\alpha/\alpha = (-0.06+/-0.06) x 10^{-5}. The median redshift of our sample (z=1.55) corresponds to a look-back time of 9.7 Gyr in the most favored cosmological model today. This gives a 3\sigma limit, -2.5 x 10^{-16} yr^-1 <(\Delta\alpha/\alpha\Delta t) <+1.2x10^{-16} yr^-1, for the time variation of \alpha, that forms the strongest constraint obtained based on high redshift quasar absorption line systems.Comment: uses revtex, 4 pages 3 figures. Accepted for publication in Physical Review Letter

Stability of Coalescence Hidden variable Fractal Interpolation Surfaces

In the present paper, the stability of Coalescence Hidden variable Fractal Interpolation Surfaces(CHFIS) is established. The estimates on error in approximation of the data generating function by CHFIS are found when there is a perturbation in independent, dependent and hidden variables. It is proved that any small perturbation in any of the variables of generalized interpolation data results in only small perturbation of CHFIS. Our results are likely to be useful in investigations of texture of surfaces arising from the simulation of surfaces of rocks, sea surfaces, clouds and similar natural objects wherein the generating function depends on more than one variable

Probing the variation of the fine-structure constant using QSO absorption lines

Search for the time variation of the fundamental constants is motivated by various unification theories. Here we present constraints on the variation of the fine-structure constant &#945;&#x2261;2/ &#x0127;c) obtained using UVES/VLT samples of QSO absorption systems. We find &lt; &#916;&#945;/&#945; &gt;w = (-0.06 &#177; 0.06) &#215; 10-5 using 23 Mg II systems and the many-multiplet (MM) method. Well selected 15 Si IV systems provide &lt; &#916;&#945;/&#945; &gt;w = (0.15 &#177; 0.43) &#215;10-5. Absence of detectable variation in &#945; is also confirmed by our new very high resolution (R ~ 100,000) observation of zabs = 1.1508 toward HE 0515-4414 using HARPS on the ESO 3.6m telescope

Probing the variation of fundamental constants using QSO absorption lines

Absorption lines seen in the spectra of distant QSOs allow us to probe the space and time evolution of various fundamental constants. Here, we summarize results on the variation of &#945; obtained by our group and others using UVES/VLT. Most upper limits reside in the range 0.5-1.5&#215;10-5 at the 3&#963; level over a redshift range of approximately 0:5 &#8804; z &#8804; 2:5. In addition, we also briefly report on preliminary results based on the analysis of 21-cm absorbers detected with Giant Meterwave Radio Telescope(GMRT) that lead to &#916;x=x = (0:0 &#177; 1:5) &#215; 10-6 at z=1.3. Discussions on future improvement are also presented

Global change and coral reef management capacity in the Pacific: engaging scientists and policy makers in Fiji, Samoa, Tuvalu and Tonga: general background dossier

Executive Summary: Sustaining healthy coral reefs is vital to the livelihoods of the people of the Pacific Islands. Global change is having increasing impacts on Pacific coral reefs, leading to increased vulnerability of coastal communities (Reefs at Risk Revisited, 2011. World Resources Institute). Integrating global change into policies across various national government sectors and then, translating this into actions that lead to sustainable management of coastal ecosystems is an enormous challenge. The project sought to address this through face-to-face dialogue between reef experts and government personnel responsible for coral reef management policies. It aimed to strengthen science-policy interaction and linkages and empower policy-makers to make informed decisions. The project targeted four countries all heavily dependent on their coral reefs: Fiji, Samoa, Tonga and Tuvalu. Using the most recent information available on the sustainable management of coral reefs, the project brought Pacific Leaders together with scientists and experts so that they could be apprised of the impacts of global change and of those factors that are affecting the health of their coral reefs. For each country this detailed national dossier was prepared by the project team in consultation with the countries, leading into two-day workshops. The dossier includes a series of issues (including gaps) pertinent to each country which were used in the development of national coral reef plans. About a year later, countries were revisited to review and measure the progress achieved on recommendations on fisheries, marine managed areas, global change and multi-sectoral, multi stakeholder consultations. Although progress varied in the four countries, it was evident that collaboration between relevant government departments needed to be improved and that there was a need for the establishment and implementation of management systems that will be on-going and self financing given the resources available. Workshops were held between June and August 2010, in which a total of some 130 senior officials from Fiji, Samoa, Tuvalu and Tonga attended. The workshops identified priority actions for coral reef management. It was found that all four countries had in place, or are developing, appropriate policies for the sustainable management of their coral reefs, taking into account the anticipated impacts of global change. All lacked, however, an overarching policy and the necessary human resources and expertise required for implementation. This situation highlights the dilemma faced by the small Pacific countries responsible for the custodianship of the unique biodiversity of their reefs. In follow-up discussions two countries (Samoa and Tuvalu), requested our assistance in the development of their National Ocean Policies which would provide the needed over-arching policy and national commitment to sustainable coral reef management. The Institute of Marine Resources has the expertise to do this but would require the necessary funding. The project provided a model for interaction between scientists and policy makers that could be readily extended to other Pacific Island countries or, for that matter, to other island states where the sustainable management of coral reefs is of vital importance for the conservation of valuable reef resources, and for maintaining the livelihoods of people