S5 0716+714 : GeV variability study

The GeV observations by Fermi-LAT give us the opportunity to characterize the high-energy emission (100 MeV - 300 GeV) variability properties of the BL Lac object S5 0716+714. In this study, we performed flux and spectral analysis of more than 3 year long (August 2008 to April 2012) Fermi-LAT data of the source. During this period, the source exhibits two different modes of flux variability with characteristic timescales of ~75 and ~140 days, respectively. We also notice that the flux variations are characterized by a weak spectral hardening. The GeV spectrum of the source shows a clear deviation from a simple power law, and is better explained by a broken power law. Similar to other bright Fermi blazars, the break energy does not vary with the source flux during the different activity states. We discuss several possible scenarios to explain the observed spectral break.Comment: 21 pages, 10 figures, Accepted for publication in Advances in Space Research journa

Risk management in landfills. A public health perspective

Currently, sanitary landfill is an appropriate option for disposal of waste, mainly because it is a technology with little aggressive environmental impact and associated to low costs and simple operation. However, the deficit in best practices in solid waste management is recognized in scientific literature as the cause of adverse effects on the environment and public health. Since landfill has a relevant social, economic and environmental impact as a sanitary urban infrastructure, new control approach based on public health and environmental integrity should be developed in order to prevent diseases propagation and negative environmental impacts. This research work presents a novel concept of landfill safety plan, using similar approach as the well established water safety plan methodology, structured on risk assessment and risk management throughout the waste collection and disposal system.CAPES scholarship and Science Without Borders program Bex Process 12993-13-

Connection between inner jet kinematics and broadband flux variability in the BL Lac object S5 0716+714

We present a high-frequency very long baseline interferometry (VLBI) kinematical study of the BL Lac object S5 0716+714 over the time period of September 2008 to October 2010. The aim of the study is to investigate the relation of the jet kinematics to the observed broadband flux variability. We find significant non-radial motions in the jet outflow of the source. In the radial direction, the highest measured apparent speed is \sim37 c, which is exceptionally high, especially for a BL Lac object. Patterns in the jet flow reveal a roughly stationary feature \sim0.15 mas downstream of the core. The long-term fits to the component trajectories reveal acceleration in the sub-mas region of the jet. The measured brightness temperature, T_{B}, follows a continuous trend of decline with distance, T_B \propto r_{jet}^{-(2.36\pm0.41)}, which suggests a gradient in Doppler factor along the jet axis. Our analysis suggest that a moving disturbance (or a shock wave) from the base of the jet produces the high-energy (optical to \gamma-ray) variations upstream of the 7 mm core, and then later causes an outburst in the core. Repetitive optical/\gamma-ray flares and the curved trajectories of the associated components suggest that the shock front propagates along a bent trajectory or helical path. Sharper \gamma-ray flares could be related to the passage of moving disturbances through the stationary feature. Our analysis suggests that the \gamma-ray and radio emission regions have different Doppler factors.Comment: 12 pages, 8 figures, accepted for publication in A&

Comparative assessment of heavy metal removal by immobilized and dead bacterial cells: A biosorption approach

Microorganisms play a vital role in heavy metal contaminated soil and wastewater by the mechanisms of biosorption. In this study, heavy metal resistant bacteria were isolated from an electroplating industrial effluent samples that uses copper, cadmium and lead for plating. These isolates were characterized to evaluate their applicability for heavy metal removal from industrial wastewaters. The physico-chemical parameters of the samples were initially analyzed. The optimum conditions of pH, biomass concentration and heavy metal concentration were determined for the microbial growth on biosorbents and correlated with heavy metal removal. The observed optimum conditions were applied for the biosorption process carried out in immobilized and dead bacterial isolates. The biosorption of immobilized cells of Bacillus sp. was 69.34% of Cu, Pseudomonas sp. was 90.41% of Cd and Micrococcus sp. was 84.27% of Pb, whereas the dead cells of Bacillus sp. was 44.73% of Cu, Pseudomonas sp. was 86.66% of Cd and Micrococcus sp. was 79.22%. Experimental results reveal that all the immobilized isolates have potential application for the removal of Cu, Cd and Pb from industrial wastewater than the dead bacterial cells

Systematic search for gamma-ray periodicity in active galactic nuclei detected by the Fermi Large Area Telescope

We use nine years of gamma-ray data provided by the Fermi Large Area Telescope (LAT) to systematically study the light curves of more than two thousand active galactic nuclei (AGN) included in recent Fermi-LAT catalogs. Ten different techniques are used, which are organized in an automatic periodicity-search pipeline, in order to search for evidence of periodic emission in gamma rays. Understanding the processes behind this puzzling phenomenon will provide a better view about the astrophysical nature of these extragalactic sources. However, the observation of temporal patterns in gamma-ray light curves of AGN is still challenging. Despite the fact that there have been efforts on characterizing the temporal emission of some individual sources, a systematic search for periodicities by means of a full likelihood analysis applied to large samples of sources was missing. Our analysis finds 11 AGN, of which 9 are identified for the first time, showing periodicity at more than 4sigma in at least four algorithms. These findings will help in solving questions related to the astrophysical origin of this periodic behavior.Comment: 16 pages, 5 figures, 4 tables. Accepted by Ap

(R2032) Modeling the Effect of Sanitation Effort on the Spread of Carrier-dependent Infectious Diseases due to Environmental Degradation

In this present study, an SIS model is proposed and analyzed to study the effect of sanitation effort in controlling the spread of carrier-dependent infectious disease in a human habitat due to environmental degradation. The dynamics of the model consist of six dependent variables, the susceptible population density, infective population density, carrier population density, cumulative density of environmental degradation and the density of sanitation effort applied on carrier population and degraded environment. In the modeling process, the carrier population density and sanitation effort are modeled logistically and the degradation of the environment is assumed to be directly proportional to the population in the habitat. The analysis of the model is performed by using the stability theory of differential equations and numerical simulations. The study of model shows that as the degradation of environment increases, the density of the carrier population increases which ultimately increases the infective population. Further, the result shows that by applying suitable sanitation effort on the carrier population density and on the cumulative density of environmental degradation, the carrier population density decreases and hence the infective population. Thus, it is very important to keep our environment clean by applying proper sanitation to prevent the spread of carrier-dependent infectious diseases

Variability of the Spectral Energy Distribution of the Blazar S5 0716+714

The emission from blazars is known to be variable at all wavelengths. The flux variability is often accompanied by spectral changes. Spectral energy distribution (SED) changes must be associated with changes in the spectra of emitting electrons and/or the physical parameters of the jet. Meaningful modeling of blazar broadband spectra is required to understand the extreme conditions within the emission region. Not only is the broadband SED crucial, but also information about its variability is needed to understand how the highest states of emission occur and how they differ from the low states. This may help in discriminating between models. Here we present the results of our SED modeling of the blazar S5 0716+714 during various phases of its activity. The SEDs are classified into different bins depending on the optical brightness state of the source.Comment: 4 pages, 3 figures, contributed talk presented at the conference Multifrequency Variability of Blazars, Guangzhou, China, September 22-24, 2010. To appear in Journal of Astrophysics and Astronomy (JAA

PRODUKSI BIOETANOL DARI HIDROLISAT AMPAS SAGUBERDASARKAN VARIASI JUMLAH RAGI ROTI (Saccharomyces cerevisiae) DAN WAKTU FERMENTASI

Ampas sagu merupakan limbah yang dihasilkan dari pengolahan sagu, yang masih  kaya akan karbohidrat dan bahan organik lainnya. Ampas sagu juga mengandung selulosa sebesar 20% yang dapat diuraikan menjadi glukosa (hidrolisat) melalui proses hidrolisis asam sulfat di mana glukosa ini dapat menjadi bahan dasar fermentasi untuk  menghasilkan bioetanol. Penelitian ini bertujuan untuk memperoleh kondisi optimum produksi bioetanol dengan memvariasikan jumlah ragi roti (Saccharomyces cerevisiae), dan lama waktu fermentasi. Hidrolisat ampas sagu (Metroxylon sp.) dengan pH awal 1,4 ditambahkan dengan larutan NaOH 80% hingga diperoleh pH 5. Ragi (Saccharomyces cerevisiae)  merupakan golongan khamir yang mampu memfermentasikan berbagai karbohidrat sederhana dan mengubah glukosa menjadi alkohol dan karbon dioksida (CO2). Jumlah ragi yang dipakai adalah 3 g, 4 g, dan 5 g, sedangkan fermentasi hidrolisat dilakukan pada pH 5 dalam skala waktu 1-10 hari. Hasil  fermentasi  (bioetanol)  dimurnikan  dengan  metode  destilasi.  Data  penelitian  menunjukkan  bahwa  kadar  bioetanol terbanyak adalah 4,25% dengan kondisi optimum jumlah ragi 4 g, waktu fermentasi 6 hari dan pH fermentasi 5. Jadi data penelitian ini dapat menjadi informasi dalam membuat rancangan optimasi produksi bioetanol selanjutnya Kata Kunci : Ampas sagu (Metroxylon sp.), bioetanol, Saccharomyces cerevisiae, fermentasi