1,238 research outputs found

    Genetic Characterization of the Tick-Borne Orbiviruses

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    The International Committee for Taxonomy of Viruses (ICTV) recognizes four species of tick-borne orbiviruses (TBOs): Chenuda virus, Chobar Gorge virus, Wad Medani virus and Great Island virus (genus Orbivirus, family Reoviridae). Nucleotide (nt) and amino acid (aa) sequence comparisons provide a basis for orbivirus detection and classification, however full genome sequence data were only available for the Great Island virus species. We report representative genome-sequences for the three other TBO species (virus isolates: Chenuda virus (CNUV); Chobar Gorge virus (CGV) and Wad Medani virus (WMV)). Phylogenetic comparisons show that TBOs cluster separately from insect-borne orbiviruses (IBOs). CNUV, CGV, WMV and GIV share low level aa/nt identities with other orbiviruses, in 'conserved' Pol, T2 and T13 proteins/genes, identifying them as four distinct virus-species. The TBO genome segment encoding cell attachment, outer capsid protein 1 (OC1), is approximately half the size of the equivalent segment from insect-borne orbiviruses, helping to explain why tick-borne orbiviruses have a ~1 kb smaller genome

    Comparison Of Dt& Gbdt Algorithms For Predictive Modeling Of Currency Exchange Rates

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    Recently, many uses of artificial intelligence have appeared in the commercial field. Artificial intelligence allows computers to analyze very large amounts of information and data, reach logical conclusions on many important topics, and make difficult decisions, this will help consumers and businesses make better decisions to improve their lives, and it will also help startups and small companies achieve great long-term success. Currency exchange rates are important matters for both governments, companies, banks and consumers. The decision tree is one of the most widely artificial intelligence tools used in data mining. With the development of this field the decision tree and Gradient boosting decision tree are used to predicate through constructed intelligent predictive system based on it. These algorithms have been used in many stock market forecasting systems based on global market data. The Iraqi dinar exchange rates for the US dollar are affected in local markets, depending on the exchange rate of the Central Bank of Iraq and the features of that auction. The proposed system is used to predict the dollar exchange rates in the Iraq markets Depending on the daily auction data of the Central Bank of Iraq (CBI). The decision tree and Gradient boosting decision tree was trained and testing using dataset of three-year issued by the CBI and compare the performance of both algorithms and find the correlation between the data. (Runtime, accuracy and correlation) criteria are adopted to select the best methods. In system, the characteristic of artificial intelligence have been integrated with the characteristic of data mining to solve problems facing organization to use available data for decision making and multi-source data linking, to provide a unified and integrated view of organization data

    Multi-frequency scatter broadening evolution of pulsars - II. Scatter broadening of nearby pulsars

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    We present multi-frequency scatter broadening evolution of 29 pulsars observed with the LOw Frequency ARray (LOFAR) and Long Wavelength Array (LWA). We conducted new observations using LOFAR Low Band Antennae (LBA) as well as utilized the archival data from LOFAR and LWA. This study has increased the total of all multi-frequency or wide-band scattering measurements up to a dispersion measure (DM) of 150~pc\,cm−3^{-3} by 60\%. The scatter broadening timescale (τsc\tau_{sc}) measurements at different frequencies are often combined by scaling them to a common reference frequency of 1\,GHz. Using our data, we show that the τsc\tau_{sc}--DM variations are best fitted for reference frequencies close to 200--300\,MHz, and scaling to higher or lower frequencies results in significantly more scatter in data. We suggest that this effect might indicate a frequency dependence of the scatter broadening scaling index (α\alpha). However, a selection bias due to our chosen observing frequencies can not be ruled out with the current data set. Our data did not favour any particular model of the DM -- τsc\tau_{sc} relations, and we do not see a statistically significant break at the low DM range in this relation. The turbulence spectral index (β\beta) is found to be steeper than that is expected from a Kolmogorov spectrum. This indicates that the local ISM turbulence may have a low wave-number cutoff or presence of large scale inhomogeneities in the line of sight to some of the reported pulsars.Comment: Accepted for publication in Ap

    Avert the Dirt:On the Design of Scalable Antifouling Polymer Coatings

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    Whether it be your house, clothes, phone, or precious record collection; everything gets dirty eventually. While we can simply hop in the shower or clean most of our belongings using basic cleaning supplies, the same does not apply to medical, marine, and industrial devices. Here, the uncontrollable and unwanted adhesion of all kinds of material, generally known as fouling, leads to serious complications related to health risks, pollution, and financial losses, which cannot be easily solved by the mere power of detergent. As a response, we strived to develop a novel antifouling coating, specifically designed for large-scale underwater applications. This protective layer consists of polymers: very long and flexible molecules. By attaching these individual polymers or polymer clusters to a surface one by one, a brush is formed, also known as a polymer brush. By repeating this adsorption step, but with a different type of polymer (cluster), the density of the brush is increased. Because of the high brush density and the used polymers’ antifouling character, fouling particles are unable to adhere to the coated surface and the surface remains clean. This simple two-step adsorption strategy has enabled the formation of an effective and reversible antifouling layer, which should allow the straightforward coating and protection of large-scale (underwater) applications. This way, we hope to contribute to a cleaner and more sustainable future

    A Search for Pulsars in Steep Spectrum Radio Sources

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    We report on a time-domain search for pulsars in 44 steep spectrum radio sources originally identified from recent imaging surveys. The time-domain search was conducted at 327 MHz using the Ooty radio telescope, and utilized a semi-coherent dedispersion scheme retaining the sensitivity even for sub-millisecond periods up to reasonably high dispersion measures. No new pulsars were found. We discuss the nature of these steep spectrum sources and argue that majority of the sources in our sample should either be pulsars or a new category of Galactic sources. Several possibilities that could hinder detection of these sources as pulsars, including anomalously high scattering or alignment of the rotation and magnetic axes, are discussed in detail, and we suggest unconventional search methods to further probe these possibilities.Comment: Accepted for publication in Ap

    Nanopyramid Structures with Light Harvesting and Self- Cleaning Properties for Solar Cells

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    In this chapter, inverted and upright nanopyramid structures with light-harvesting properties and self-cleaning hydrophobic surfaces suitable for solar cells are presented. Periodic nanopyramid structures with 400–700 nm features were fabricated using interference lithography and combined dry and wet etching processes. The inverted nanopyramids (INP) were applied at the front side of the solar cells using UV nanoimprint lithography. These structures provided effective light-trapping properties and led to oblique angle light scattering and a significant reduction in reflectance resulting in higher power conversion efficiency. The second type, the periodic upright nanopyramid (UNP) structures were applied on a glass substrate by UV nanoimprint process. The glass cover is also utilized as a protective encapsulant front layer. The use of the upright nanopyramid structured cover glass in the encapsulated solar cell has also enhanced the power conversion efficiency due to the antireflection and strong light-scattering properties compared to the bare cover glass. In addition, the upright nanopyramid structured cover glass exhibited excellent self-cleaning of dust particles by rolling down water droplets. These results suggest that the nanopyramid structures with light-harvesting and self-cleaning properties can improve the performance of different types of solar cells, including thin films and glass-based PVs

    Fabrication and Replication of Periodic Nanopyramid Structures by Laser Interference Lithography and UV Nanoimprint Lithography for Solar Cells Applications

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    In this chapter, the fabrication and replication of periodic nanopyramid structures suitable for antireflection and self-cleaning surfaces are presented. Laser interference lithography (LIL), dry etching, wet etching, and UV nanoimprint lithography (UV-NIL) are employed for the fabrication and replication of periodic nanopyramid structures. Inverted nanopyramid structures were fabricated on Si substrates by LIL and subsequent pattern transfer process using reactive ion etching, followed by potassium hydroxide (KOH) wet etching. The fabricated periodic inverted nanopyramid structures were utilized as a master mold for the nanoimprint process. The upright nanopyramid structures were patterned on the OrmoStamp-coated glass substrate with high fidelity in the first nanoimprint process. In the second nanoimprint process, inverted nanopyramid structures were replicated on the OrmoStamp-coated substrate using the fabricated upright nanopyramid glass substrate as a mold. The replicated inverted nanopyramid structure on resist-coated substrate was faithfully resolved with the high accuracy compared to original Si master mold down to nanometer scale. Both upright and inverted nanopyramid structures can be utilized as surface coatings for light trapping and self-cleaning applications for different types of solar cell and glass surfaces

    Quantum-Hall activation gaps in graphene

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    We have measured the quantum-Hall activation gaps in graphene at filling factors ν=2\nu=2 and ν=6\nu=6 for magnetic fields up to 32 T and temperatures from 4 K to 300 K. The ν=6\nu =6 gap can be described by thermal excitation to broadened Landau levels with a width of 400 K. In contrast, the gap measured at ν=2\nu=2 is strongly temperature and field dependent and approaches the expected value for sharp Landau levels for fields B>20B > 20 T and temperatures T>100T > 100 K. We explain this surprising behavior by a narrowing of the lowest Landau level.Comment: 4 pages, 4 figures, updated version after review, accepted for PR
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