A Framework for Similarity Search with Space-Time Tradeoffs using Locality Sensitive Filtering

We present a framework for similarity search based on Locality-Sensitive Filtering~(LSF),generalizing the Indyk-Motwani (STOC 1998) Locality-Sensitive Hashing~(LSH) framework to support space-time tradeoffs. Given a family of filters, defined as a distribution over pairs of subsets of space that satisfies certain locality-sensitivity properties, we can construct a dynamic data structure that solves the approximate near neighbor problem in $d$-dimensional space with query time $dn^{\rho_q + o(1)}$, update time $dn^{\rho_u + o(1)}$, and space usage $dn + n^{1 + \rho_u + o(1)}$ where $n$ denotes the number of points in the data structure.The space-time tradeoff is tied to the tradeoff between query time and update time (insertions/deletions), controlled by the exponents $\rho_q, \rho_u$ that are determined by the filter family. \\ Locality-sensitive filtering was introduced by Becker et al. (SODA 2016) together with a framework yielding a single, balanced, tradeoff between query time and space, further relying on the assumption of an efficient oracle for the filter evaluation algorithm.We extend the LSF framework to support space-time tradeoffs and through a combination of existing techniques we remove the oracle assumption. \\Laarhoven (arXiv 2015), building on Becker et al., introduced a family of filters with space-time tradeoffs for the high-dimensional unit sphere under inner product similarity and analyzed it for the important special case of random data.We show that a small modification to the family of filters gives a simpler analysis that we use, together with our framework, to provide guarantees for worst-case data. Through an application of Bochner's~Theorem from harmonic analysis by Rahimi \& Recht (NIPS 2007), we are able to extend our solution on the unit sphere to $\real^d$ under the class of similarity measures corresponding to real-valued characteristic functions.For the characteristic functions of $s$-stable distributions we obtain a solution to the $(r, cr)$-near neighbor problem in $\ell_s^d$-spaces with query and update exponents $\rho_q = \frac{c^s (1+\lambda)^2}{(c^s + \lambda)^2}$ and $\rho_u = \frac{c^s (1-\lambda)^2}{(c^s + \lambda)^2}$where $\lambda \in [-1,1]$ is a tradeoff parameter. This result improves upon the space-time tradeoff of Kapralov (PODS 2015) and is shown to be optimal in the case of a balanced tradeoff, matching the LSH lower bound by O'Donnell et al.~\mbox{(ITCS 2011)} and a similar LSF lower bound proposed in this paper.Finally, we show a lower bound for the space-time tradeoff on the unit sphere that matches Laarhoven's and our own upper bound in the case of random data

The Livestock Economy of Pakistan: An Agricultural Sector Model Approach

The Pakistan Agricultural Sector Model (PASM) developed by Davies et al. (1991) was modified to enhance the livestock sub-sector. Nutrient-based rations replaced feedstuff-based rations and dry matter minimum and maximum constraints (stomach capacity) were added. Several initial simulations were undertaken to examine the structure of the modified model and its impact across the crop and livestock sub-sectors. These simulations included relaxing exogenous livestock numbers and selected crop hectarage constraints, and requiring that green forage be fed in the season grown. Most importantly, the results demonstrated that fodder hectarage will grow with livestock numbers to insure that sufficient green forage is available seasonally. Two other analyses were performed to demonstrate the need to specify linkages between the crop and livestock sub-sectors. An analysis of transforming the livestock sub-sector from traditional to feedlot-based technology demonstrated that the reduced numbers of non-milking cattle needed for a given output of meat would provide the potential for increased production of various crops and other livestock products. Also, expanded cotton and Irri rice exports, hypothesised to occur through trade liberalisation from the Uruguay Round of the GATT, highlighted other inter-relationships between the crop and livestock sub-sectors. Greater production of both livestock and other crops might accompany the expansion of cotton production but less livestock feed would be available with expanded exports of Irri rice.

Innovation and Technology Dissemination in Clean Technology Markets and the Developing World: The Role of Trade, Intellectual Property Rights, and Uncertainty

Innovation is an inherently risky and uncertain process. Many of the broader challenges to innovation in general are both mirrored and exaggerated in clean technology innovation. The development of environmental technologies is further complicated by the public goods nature of knowledge, environmental externalities, and uncertainty. This study on clean technology focuses on recent work on the role of uncertainty, the participation of emerging and developing nations, the controversy surrounding intellectual property rights, and the variety of market actors and strategies in place. The paper also considers the policy instruments that are available, the cost, benefits and consequences of their use. As scholars continue to analyze when, where, why and how clean technology innovations are developed and adopted, it is essential that government policymakers aim to reduce uncertainty and risk, incentivize innovation with effective intellectual property rights, and foster transparency in the market. This continues to be a field of increasing future importance, and a rich area for continued academic study and analysis. Consumers, government policymakers and innovators would all benefit from a greater understanding of the process of technological change in the development, diffusion and financing of clean technologies.Innowacja to proces z natury ryzykowny i niepewny. Wiele wyzwań związanych z innowacjami dotyczy również czystych technologii. Rozwój technologii środowiskowych jest ponadto utrudniony ze względu na specyfikę wiedzy, efekty zewnętrzne i niepewność. Niniejsza analiza koncentruje się na przeglądzie literatury na temat roli niepewności, zaangażowania państw rozwijających się, kontrowersji dotyczących praw własności intelektualnej oraz uczestników rynku i ich strategii. Praca ta rozważa także dostępne instrumenty polityki, koszty, korzyści i konsekwencje ich zastosowania. Naukowcy wciąż analizują to kiedy, gdzie, dlaczego i jak tworzone i rozwijane są innowacje dotyczące czystych technologii. Niezbędne jest, aby twórcy polityki rządów dążyli do redukcji niepewność i ryzyka, stymulowali innowacje poprzez skuteczne egzekwowanie praw własności intelektualnej oraz wspierali przejrzystość rynku. Kwestie te będą odgywać coraz większą rolę w przyszłości, stając się przedmiotem dalszych badań i analiz naukowych. Konsumenci, twórcy polityki rządowej oraz innowatorzy mogliby odnieść korzyści z lepszego zrozumienia procesu zmian technologicznych, związanych z rozwojem, dyfuzją i finansowaniem czystych technologii

Study of E. coli Hfq's RNA annealing acceleration and duplex destabilization activities using substrates with different GC-contents

Folding of RNA molecules into their functional three-dimensional structures is often supported by RNA chaperones, some of which can catalyse the two elementary reactions helix disruption and helix formation. Hfq is one such RNA chaperone, but its strand displacement activity is controversial. Whereas some groups found Hfq to destabilize secondary structures, others did not observe such an activity with their RNA substrates. We studied Hfq’s activities using a set of short RNAs of different thermodynamic stabilities (GC-contents from 4.8% to 61.9%), but constant length. We show that Hfq’s strand displacement as well as its annealing activity are strongly dependent on the substrate’s GC-content. However, this is due to Hfq’s preferred binding of AU-rich sequences and not to the substrate’s thermodynamic stability. Importantly, Hfq catalyses both annealing and strand displacement with comparable rates for different substrates, hinting at RNA strand diffusion and annealing nucleation being rate-limiting for both reactions. Hfq’s strand displacement activity is a result of the thermodynamic destabilization of the RNA through preferred single-strand binding whereas annealing acceleration is independent from Hfq’s thermodynamic influence. Therefore, the two apparently disparate activities annealing acceleration and duplex destabilization are not in energetic conflict with each other

USER'S GUIDE - GENERAL WEED MANAGEMENT MODEL VERSION 1.0 - DECEMBER 1994

Crop Production/Industries,

Korea’s near-Term economic prospects and challenges

노트 : A publication of the Korea Economic Institute and the Korea Institute for International Economic Polic

PUFFINN: Parameterless and Universally Fast FInding of Nearest Neighbors

We present PUFFINN, a parameterless LSH-based index for solving the k-nearest neighbor problem with probabilistic guarantees. By parameterless we mean that the user is only required to specify the amount of memory the index is supposed to use and the result quality that should be achieved. The index combines several heuristic ideas known in the literature. By small adaptions to the query algorithm, we make heuristics rigorous. We perform experiments on real-world and synthetic inputs to evaluate implementation choices and show that the implementation satisfies the quality guarantees while being competitive with other state-of-the-art approaches to nearest neighbor search. We describe a novel synthetic data set that is difficult to solve for almost all existing nearest neighbor search approaches, and for which PUFFINN significantly outperform previous methods

Scalable and Robust Set Similarity Join

Set similarity join is a fundamental and well-studied database operator. It is usually studied in the exact setting where the goal is to compute all pairs of sets that exceed a given similarity threshold (measured e.g. as Jaccard similarity). But set similarity join is often used in settings where 100% recall may not be important --- indeed, where the exact set similarity join is itself only an approximation of the desired result set. We present a new randomized algorithm for set similarity join that can achieve any desired recall up to 100%, and show theoretically and empirically that it significantly improves on existing methods. The present state-of-the-art exact methods are based on prefix-filtering, the performance of which depends on the data set having many rare tokens. Our method is robust against the absence of such structure in the data. At 90% recall our algorithm is often more than an order of magnitude faster than state-of-the-art exact methods, depending on how well a data set lends itself to prefix filtering. Our experiments on benchmark data sets also show that the method is several times faster than comparable approximate methods. Our algorithm makes use of recent theoretical advances in high-dimensional sketching and indexing that we believe to be of wider relevance to the data engineering community

Compulsory Licensing of Patented Pharmaceutical Inventions: Evaluating the Options

In this Comment, the author traces the relevant legislative history pertaining to compulsory licensing of patented pharmaceuticals from the TRIPS Agreement of 1994 to the 2003 waiver to, and later proposed amendment of, article 31, which enables poor countries to obtain needed medicines from other countries that possess manufacturing capacity. The Comment then evaluates recent, controversial uses of the relevant legislative machinery as viewed from different critical perspectives. The Comment shows how developing countries seeking access to esential medicines can collaborate in ways that would avoid undermining incentives to innovation and other social costs attributed to compulsory licensing. It ends by defending the legality of recent measures taken to promote public health in developing countries, and by reminding developed countries that unilateral retaliation against such measures is demonstrably illegal under WTO foundational law and jurisprudence