1,447 research outputs found

    A 3D topological insulator quantum dot for optically controlled quantum memory and quantum computing

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    We present the model of a quantum dot (QD) consisting of a spherical core-bulk heterostructure made of 3D topological insulator (TI) materials, such as PbTe/Pb0.31_{0.31}Sn0.69_{0.69}Te, with bound massless and helical Weyl states existing at the interface and being confined in all three dimensions. The number of bound states can be controlled by tuning the size of the QD and the magnitude of the core and bulk energy gaps, which determine the confining potential. We demonstrate that such bound Weyl states can be realized for QD sizes of few nanometers. We identify the spin locking and the Kramers pairs, both hallmarks of 3D TIs. In contrast to topologically trivial semiconductor QDs, the confined massless Weyl states in 3D TI QDs are localized at the interface of the QD and exhibit a mirror symmetry in the energy spectrum. We find strict optical selection rules satisfied by both interband and intraband transitions that depend on the polarization of electron-hole pairs and therefore give rise to the Faraday effect due to Pauli exclusion principle. We show that the semi-classical Faraday effect can be used to read out spin quantum memory. When a 3D TI QD is embedded inside a cavity, the single-photon Faraday rotation provides the possibility to implement optically mediated quantum teleportation and quantum information processing with 3D TI QDs, where the qubit is defined by either an electron-hole pair, a single electron spin, or a single hole spin in a 3D TI QD. Remarkably, the combination of inter- and intraband transition gives rise to a large dipole moment of up to 450 Debye. Therefore, the strong-coupling regime can be reached for a cavity quality factor of Q104Q\approx10^{4} in the infrared wavelength regime of around 10μ10\:\mum.Comment: 19 pages, 11 figures, RevTe

    Test of Convergence in Agricultural Factor Productivity: A Semiparametric Approach

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    We tested for club convergence in U.S. agricultural total factory productivity using a sigma convergence test. We used the same club of states as used by McCunn and Huffman as well as different states within 10 clubs identified by the cluster analysis. Results showed convergence was evident only in a few club groups. Clusters group identified using a statistical method identified only converging clubs. Variables affecting total factor productivity among states were identified using parametric, semiparametric and nonparametric methods. Semiparametric and nonparametric methods gave a better fit than a parametric method as indicated by the specification test. Our results indicated that health care expenditure, public research and extension investment, and private expenditure are important variables impacting total factor productivity differences across states.Clubs, sigma convergence, cluster analysis, semiparametric and nonparametric methods, Productivity Analysis, Research Methods/ Statistical Methods,

    Searching for an Environmental Kuznets Curve in Carbon Dioxide Pollutant in Latin American Countries

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    This study utilized a semiparametric panel model to estimate environmental Kuznets curves (EKC) for carbon dioxide (CO2) in 15 Latin American countries, using hitherto unused data on forestry acreage in each country. Results showed an N-shaped curve for the region; however, the shape of the curve is sensitive to the removal of some groups of countries. Specification tests support a semiparametric panel model over a parametric quadratic specification.CO2, forest acreage, environmental Kuznets curve, Latin American countries, semiparametric regression model, Agribusiness, Environmental Economics and Policy, Research and Development/Tech Change/Emerging Technologies, C14, C33, Q23, Q53,

    Multiple Cropping for Raising Productivity and Farm Income of Small Farmers

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    Multiple cropping is an agriculture system long adopted by marginalized small holder farmers especially in hills and mountains. This practice was a meant to enhance farm productivity when farming area is limited. Here, in this paper, a brief review on the benefits of multiple cropping is presented focusing on the practices adopted by marginalized farmers, in general. In multiple cropping, it is generally argued that the practice favors an efficient utilization of resources like air, water, light, space, and nutrients by companion crops in both temporal and spatial dimensions due to their differential growth habits and seasonality. Multiple cropping could be one of the viable alternatives to cope uncertainties and changes, where food and nutritional uncertainty looming large. The ultimate outcome of multiple cropping could be visualized in adverse or harsh environment for increase agriculture production, livelihood and income. Various food products are obtained through multiple cropping. Land equivalent ratio (LER), relative yield total (RYT) and income equivalent ratio (IER) can be increased with mixed/intercropping systems. Multiple cropping helps in getting more than one crop simultaneously, so even if the selling price of one commodity is less, the other might compensate. In the tropics, smallholder farms, which produce over 60% of the food resources of developing nations from intercropping of cereals with many crops mostly legumes, had been the field of much investigation because of synergistic effects of diversifying food production and household cash incomes in these systems. This clearly implies the importance of multiple cropping for small farmers who constitute majority in the developing countries

    Phytochemical profile and biological activity of Nelumbo nucifera

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    © 2015 Keshav Raj Paudel and Nisha Panth. Nelumbo nucifera Gaertn. (Nymphaeaceae) is a potential aquatic crop grown and consumed throughout Asia. All parts of N. nucifera have been used for various medicinal purposes in various systems of medicine including folk medicines, Ayurveda, Chinese traditional medicine, and oriental medicine. Many chemical constituents have been isolated till the date. However, the bioactive constituents of lotus are mainly alkaloids and flavonoids. Traditionally, the whole plant of lotus was used as astringent, emollient, and diuretic. It was used in the treatment of diarrhea, tissue inflammation, and homeostasis. The rhizome extract was used as antidiabetic and anti-inflammatory properties due to the presence of asteroidal triterpenoid. Leaves were used as an effective drug for hematemesis, epistaxis, hemoptysis, hematuria, and metrorrhagia. Flowers were used to treat diarrhea, cholera, fever, and hyperdipsia. In traditional medicine practice, seeds are used in the treatment of tissue inflammation, cancer and skin diseases, leprosy, and poison antidote. Embryo of lotus seeds is used in traditional Chinese medicine as Lian Zi Xin, which primarily helps to overcome nervous disorders, insomnia, and cardiovascular diseases (hypertension and arrhythmia). Nutritional value of lotus is as important as pharmaceutical value. These days' different parts of lotus have been consumed as functional foods. Thus, lotus can be regarded as a potential nutraceutical source

    Photoluminescence Quenching in Single-layer MoS2 via Oxygen Plasma Treatment

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    By creating defects via oxygen plasma treatment, we demonstrate optical properties variation of single-layer MoS2. We found that, with increasing plasma exposure time, the photoluminescence (PL) evolves from very high intensity to complete quenching, accompanied by gradual reduction and broadening of MoS2 Raman modes, indicative of distortion of the MoS2 lattice after oxygen bombardment. X-ray photoelectron spectroscopy study shows the appearance of Mo6+ peak, suggesting the creation of MoO3 disordered regions in the MoS2 flake. Finally, using band structure calculations, we demonstrate that the creation of MoO3 disordered domains upon exposure to oxygen plasma leads to a direct to indirect bandgap transition in single-layer MoS2, which explains the observed PL quenching.Comment: 12 pages, 7 figure

    Rapid silviculture appraisal to characterise stand and determine silviculture priorities of community forests in Nepal

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    Published online: 7 September 2016Community forestry in Nepal is an example of a successful participatory forest management program. Developments in community forestry in four decades have focused on the social and governance aspects with little focus on the technical management of forests. This paper presents a silviculture description of community forests and provides silviculture recommendations using a rapid silviculture appraisal (RSA) approach. The RSA, which is a participatory technique involving local communities in assessing forests and silviculture options, is a simple and costeffective process to gather information and engage forest users in the preparation of operational plans that are relevant to their needs. The RSA conducted on selected community forests in Nepal’s Mid-hills region shows that forests are largely comprised of dominant crowns of one or two species. The majority of studied community forests have tree densities below 500 stems per hectare as a consequence of traditional forest management practices but the quality and quantity of the trees for producing forest products are low. Silviculture options preferred by forest users generally are those which are legally acceptable, doable with existing capacities of forest users and generate multiple forest products. For sustainable production of multiple forest products, the traditional forest management practices have to be integrated with silviculture-based forest management system.Edwin Cedamon, Ian Nuberg, Govinda Paudel, Madan Basyal, Krishna Shrestha, Naya Paude

    An Analysis of Rank Ordered Data

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    Many methods are available to analyze rank ordered data. We used a spectral density method to analyze Formosan subterranean termite control options ranked by Louisiana homeowners. Respondents are asked to rank termite control options from the most preferred to the least preferred option. Spectral analysis results indicated that the most preferred termite control choice is a relatively cheap ($0.13 per square foot) option of liquid treatment.FST, rank ordered data, spectral analysis, Research Methods/ Statistical Methods,

    EXAMINING THE CRB INDEX AS AN INDICATOR FOR U.S. INFLATION

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    This paper analyzes historical movements in the commodity futures market and the relationship to inflation. Specifically, the relationship between the Commodity Research Bureau (CRB) Index and United States inflation is investigated. It is said that the relationship between the CRB index and the U.S. inflation rate was greater in the some periods than in another period. Then in recent times the CRB Index has proven to be a reliable early indicator of inflation. As the composition of the United States economy changes, the Commodity Research Bureau must make adjustments in order to provide a viable service.CRB index, Commodities Research Bureau, inflation, Vector Autoregression, Marketing, Public Economics, E00, E30,

    Reactive Oxygen Species: A Key Hallmark of Cardiovascular Disease.

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    Cardiovascular diseases (CVDs) have been the prime cause of mortality worldwide for decades. However, the underlying mechanism of their pathogenesis is not fully clear yet. It has been already established that reactive oxygen species (ROS) play a vital role in the progression of CVDs. ROS are chemically unstable reactive free radicals containing oxygen, normally produced by xanthine oxidase, nicotinamide adenine dinucleotide phosphate oxidase, lipoxygenases, or mitochondria or due to the uncoupling of nitric oxide synthase in vascular cells. When the equilibrium between production of free radicals and antioxidant capacity of human physiology gets altered due to several pathophysiological conditions, oxidative stress is induced, which in turn leads to tissue injury. This review focuses on pathways behind the production of ROS, its involvement in various intracellular signaling cascades leading to several cardiovascular disorders (endothelial dysfunction, ischemia-reperfusion, and atherosclerosis), methods for its detection, and therapeutic strategies for treatment of CVDs targeting the sources of ROS. The information generated by this review aims to provide updated insights into the understanding of the mechanisms behind cardiovascular complications mediated by ROS
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