10,440 research outputs found

    Sensible and latent heating of the atmosphere as inferred from DST-6 data

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    The average distribution of convective latent heating, boundary layer sensible heat flux, and vertical velocity are determined for the winter 1976 DST period from GLAS model diagnostics. Key features are the regions of intense latent heating over Brazil, Central Africa, and Indonesia; and the regions of strong sensible heating due to air mass modification over the North Atlantic and North Pacific Oceans

    Deformation of Silica Aerogel During Fluid Adsorption

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    Aerogels are very compliant materials - even small stresses can lead to large deformations. In this paper we present measurements of the linear deformation of high porosity aerogels during adsorption of low surface tension fluids, performed using a Linear Variable Differential Transformer (LVDT). We show that the degree of deformation of the aerogel during capillary condensation scales with the surface tension, and extract the bulk modulus of the gel from the data. Furthermore we suggest limits on safe temperatures for filling and emptying low density aerogels with helium.Comment: 8 pages, 5 figures, submitted to PR

    Private Sector and Climate Change A Case Study of Carbon-Based Governance

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    Global greenhouse gas emissions are the main contributor to anthropocentrically-induced climate change and have risen 41% since 1990. We are still yet to reach peak emissions. A large share of those emissions result from private sector activity. At the same time, the private sector possesses major resources which should be harnessed to scale up funding and emissions reduction technologies to benefit the 3 climate. Since the Paris Climate Agreement in 2015, there has been an upsurge in private sector activity on climate change, especially in the corporate sector. Researchers have suggested that this groundswell of private sector activity especially in reduction of carbon emissions holds out the promise of plugging conspicuous public governance gaps. But while this surge in private action since the Paris Climate Agreement is to be encouraged, and indeed has been formally welcomed by global public climate governance actors under the UNFCCC, the measurable success of private, public-private and “hybrid” climate governance arrangements on reducing emissions remains unclear. Through an in depth empirical investigation of the actors and initiatives that play a key role in this emerging domain of bottom-up climate change governance, this study finds that, despite a groundswell in private activity, zones of fragmentation among a multiplicity of private actors, initiatives and standards is stymying progress: while key actors are increasingly networked, key metrics remain severely fragmented; while substantial resources have been dedicated to governing carbon emissions, greenhouse gas emissions keep rising. These observations are demonstrated through an empirical analysis of the “carbon-based” governance regime, which we define as the governance of climate change through a unitary focus on carbon measurement, disclosure, and verification. So far, the ultimate goal of carbon-based governance to reduce emissions is far from being realized. Whether this regime can be repurposed to fulfil this crucial function remains an open question

    Pengaruh Problem Based Learning (PBL) terhadap Kemampuan Heuristik Pemecahan Masalah dan Sikap Matematis Siswa Sekolah Dasar

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    Penelitian ini dilatarbelakangi oleh rendahnya kemampuan heuristik pemecahan masalah dan sikap matematis siswa terhadap pelajaran matematika. Penelitian ini bertujuan untuk menelaah perbedaan peningkatan kemampuan pemecahan masalah dan sikap matematis siswa yang menggunakan Problem Based Learning (PBL) dengan siswa yang menggunakan pembelajaran konvensional. Metode dalam penelitian ini menggunakan desain kuasi eksperimen dengan subjek penelitian seluruh siswa kelas V SD Negeri Leuwikujang I sebagai kelas eksperimen dan seluruh siswa kelas V SD Negeri Rajawangi I sebagai kelas kontrol. Instrumen yang digunakan adalah tes kemampuan pemecahan masalah dan skala sikap matematis siswa. Data hasil penelitian berupa skor pra tes dan pasca tes siswa dianalisis dengan menggunakan uji t dan uji korelasi Product Moment Pearson. Berdasarkan hasil analisis data diperoleh kesimpulan bahwa, siswa yang mendapatkan pembelajaran Problem Based Learning (PBL) mengalami peningkatan pada kemampuan strategi heuristic pemecahan masalah dan sikap matematis yang lebih baik dibandingkan dengan siswa yang mendapatkan pembelajaran matematika secara konvensional

    ADOPTION OF VETERINARY SURGEON SERVICES BY SHEEP AND GOAT FARMERS IN QWAQWA

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    A number of technology transfer (diffusion) programmes involving amongst others veterinary surgeon services subsidised by the government, were launched in the former homelands of South Africa between 1980 and 1993. Many of these programmes were discontinued after the general election of 1994. In order to evaluate the adoption of technology in Qwaqwa, a former Sotho speaking homeland, two Logit models were fit using the conventional definition of an adopter and an adapted definition, which included potential adopters with the adopters. Where the conventional definition of adoption was estimated, livestock income per LSU, ram technology, roads and suppliers of livestock inputs are significant variables contributing to adoption. The results of the adapted model reveal that farming efficiency (weaning percentage), type of farmer (sheep as percentage of the total small ruminant herd) and ram technology, prove to be significant variables predicting adoption. It was also found that the characteristics of potential adopters gravitate more to adopters than to non-adopters. These results indicated that the adapted definition presented a more accurate prediction than the conventional definition. The results of this study indicate the policy necessary to further accelerate the diffusion of veterinary surgeon services by means of the development of a better infrastructure, the reintroduction of subsidised veterinary surgeon services at the sheering sheds as well as a better flow of information to farmers in Qwaqwa.Livestock Production/Industries,

    Diluted maximum-likelihood algorithm for quantum tomography

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    We propose a refined iterative likelihood-maximization algorithm for reconstructing a quantum state from a set of tomographic measurements. The algorithm is characterized by a very high convergence rate and features a simple adaptive procedure that ensures likelihood increase in every iteration and convergence to the maximum-likelihood state. We apply the algorithm to homodyne tomography of optical states and quantum tomography of entangled spin states of trapped ions and investigate its convergence properties.Comment: v2: Convergence proof adde

    EVALUATION OF ALTERNATIVE FILTER MEDIA FOR THE ROTARY MICROFILTER

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    The Savannah River Site is currently developing and testing several processes to treat high level radioactive liquid waste. Each of these processes has a solid-liquid separation process that limits its throughput. Savannah River National Laboratory researchers identified and tested the rotary microfilter as a technology to increase solid-liquid separation throughput. The authors believe the rotary microfilter throughput can be improved by using a better filter membrane. Previous testing showed that asymmetric filters composed of a ceramic membrane on top of a stainless steel support produced higher filter flux than 100% stainless steel symmetric filters in crossflow filter tests. Savannah River National Laboratory and Oak Ridge National Laboratory are working together to develop asymmetric ceramic ? stainless steel composite filters and asymmetric 100% stainless steel filters to improve the throughput of the rotary microfilter. The Oak Ridge National Laboratory Inorganic Membrane Group fabricated samples of alternative filter membranes. In addition, Savannah River National Laboratory obtained samples of filter membranes from Pall, Porvair, and SpinTek. They tested these samples in a static test cell with feed slurries containing monosodium titanate and simulated sludge

    Role of social environment and social clustering in spread of opinions in co-evolving networks

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    Taking a pragmatic approach to the processes involved in the phenomena of collective opinion formation, we investigate two specific modifications to the co-evolving network voter model of opinion formation, studied by Holme and Newman [1]. First, we replace the rewiring probability parameter by a distribution of probability of accepting or rejecting opinions between individuals, accounting for the asymmetric influences in relationships among individuals in a social group. Second, we modify the rewiring step by a path-length-based preference for rewiring that reinforces local clustering. We have investigated the influences of these modifications on the outcomes of the simulations of this model. We found that varying the shape of the distribution of probability of accepting or rejecting opinions can lead to the emergence of two qualitatively distinct final states, one having several isolated connected components each in internal consensus leading to the existence of diverse set of opinions and the other having one single dominant connected component with each node within it having the same opinion. Furthermore, and more importantly, we found that the initial clustering in network can also induce similar transitions. Our investigation also brings forward that these transitions are governed by a weak and complex dependence on system size. We found that the networks in the final states of the model have rich structural properties including the small world property for some parameter regimes. [1] P. Holme and M. Newman, Phys. Rev. E 74, 056108 (2006)
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