28,762 research outputs found

    Spatial Price Integration in U.S. and Mexican Rice Markets

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    Agricultural trade between the U.S. and Mexico has become progressively liberalized over the past 20 years, with significant increases in bilateral trade in many sectors. The rice sector in both nations, however, continues to be highly protected, with producers and millers on both sides of the border continuing to protest the other nation's protectionist policies. This paper examines market efficiency and spatial price integration in ten U.S. and Mexican rice markets over the 1998-2002 period, during which a retaliatory antidumping duty was imposed by Mexico. The paper uses a multiple step analytical process, including analysis of market price differentials, stationarity tests, bivariate and multivariate cointegration tests, and impulse response analysis. Based on the cointegration results, long-run equilibrating relationships are shown to bind most Mexican markets to U.S. markets, and the U.S. markets are shown to be integrated with continuity. Smaller and more remote Mexican markets located far from transport hubs and milling centers tend not to be integrated with other regions, suffer from information asymmetries, and are characterized by relatively high price levels. In large markets where tariffs tend to be binding, trade policy plays a key role in determining equilibrium market relationships. For example, the tariff structure largely determines whether rice consumed in Mexico will primarily be milled domestically or in the U.S. in the long run. Overall, the results suggest that while consumers in major urban centers have benefited from freer trade, those in remote rural markets have yet to realize significant gains from liberalized rice markets.Crop Production/Industries, Demand and Price Analysis,

    Design, modeling, and analysis of multi-channel demultiplexer/demodulator

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    Traditionally, satellites have performed the function of a simple repeater. Newer data distribution satellite architectures, however, require demodulation of many frequency division multiplexed uplink channels by a single demultiplexer/demodulator unit, baseband processing and routing of individual voice/data circuits, and remodulation into time division multiplexed (TDM) downlink carriers. The TRW MCDD (Multichannel Demultiplexer/Multirate Demodulator) operates on a 37.4 MHz composite input signal. Individual channel data rates are either 64 Kbps or 2.048 Mbps. The wideband demultiplexer divides the input signal into 1.44 MHz segments containing either a single 2.048 Mbps channel or thirty two 64 Kbps channels. In the latter case, the narrowband demultiplexer further divides the single 1.44 MHz wideband channel into thirty two 45 KHz narrowband channels. With this approach the time domain Fast Fourier Transformation (FFT) channelizer processing capacity is matched well to the bandwidth and number of channels to be demultiplexed. By using a multirate demodulator fewer demodulators are required while achieving greater flexibility. Each demodulator can process a wideband channel or thirty two narrowband channels. Either all wideband channels, a mixture of wideband and narrowband channels, or all narrowband channels can be demodulated. The multirate demodulator approach also has lower nonrecurring costs since only one design and development effort is needed. TRW has developed a proof of concept (POC) model which fully demonstrates the signal processing fuctions of MCDD. It is capable of processing either three 2.048 Mbps channels or two 2.048 Mbps channels and thirty two 64 Kbps channels. An overview of important MCDD system engineering issues is presented as well as discussion on some of the Block Oriented System Simulation analyses performed for design verification and selection of operational parameters of the POC model. Systems engineering analysis of the POC model confirmed that the MCDD concepts are not only achievable but also balance the joint goals of minimizing on-board complexity and cost of ground equipment, while retaining the flexibility needed to meet a wide range of system requirements

    Biochemical Properties of a Decoy Oligodeoxynucleotide Inhibitor of STAT3 Transcription Factor.

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    Cyclic STAT3 decoy (CS3D) is a second-generation, double-stranded oligodeoxynucleotide (ODN) that mimics a genomic response element for signal transducer and activator of transcription 3 (STAT3), an oncogenic transcription factor. CS3D competitively inhibits STAT3 binding to target gene promoters, resulting in decreased expression of proteins that promote cellular proliferation and survival. Previous studies have demonstrated antitumor activity of CS3D in preclinical models of solid tumors. However, prior to entering human clinical trials, the efficiency of generating the CS3D molecule and its stability in biological fluids should be determined. CS3D is synthesized as a single-stranded ODN and must have its free ends ligated to generate the final cyclic form. In this study, we report a ligation efficiency of nearly 95 percent. The ligated CS3D demonstrated a half-life of 7.9 h in human serum, indicating adequate stability for intravenous delivery. These results provide requisite biochemical characterization of CS3D that will inform upcoming clinical trials

    Improved Bounds on Information Dissemination by Manhattan Random Waypoint Model

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    With the popularity of portable wireless devices it is important to model and predict how information or contagions spread by natural human mobility -- for understanding the spreading of deadly infectious diseases and for improving delay tolerant communication schemes. Formally, we model this problem by considering MM moving agents, where each agent initially carries a \emph{distinct} bit of information. When two agents are at the same location or in close proximity to one another, they share all their information with each other. We would like to know the time it takes until all bits of information reach all agents, called the \textit{flood time}, and how it depends on the way agents move, the size and shape of the network and the number of agents moving in the network. We provide rigorous analysis for the \MRWP model (which takes paths with minimum number of turns), a convenient model used previously to analyze mobile agents, and find that with high probability the flood time is bounded by O(NlogM(N/M)log(NM))O\big(N\log M\lceil(N/M) \log(NM)\rceil\big), where MM agents move on an N×NN\times N grid. In addition to extensive simulations, we use a data set of taxi trajectories to show that our method can successfully predict flood times in both experimental settings and the real world.Comment: 10 pages, ACM SIGSPATIAL 2018, Seattle, U

    A Multi-Factor Analysis of AREIT Returns

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    Since 1990, the Australian Real Estate Investment Trust (AREIT) sector has experienced substantial growth and popularity. While the AREIT sector had benefit from the increased flow of funds from institutional investors during the 1997 Asian financial crisis, the recent impact of the 2008 global financial crisis has been a negative one. In this paper, we examine the sensitivities of annualised AREIT returns against a set of seven firm-specific variables and four market-wide risk variables. Balanced and unbalanced panel regressions are conducted on three sub-periods during 1990 - 2008 corresponding to the major phases in evolution of the AREIT sector. Our regression results find that size has a negative impact on returns, and this effect has been diminishing over time. Overall market risk was also found to be significant and positive only since 2003, suggesting that recently AREITs behave more like stocks and less like defensive assets. The relationship with exchange rate risk has been positive in recent years, due to more AREITs choosing to diversify internationally, particularly in the U.S. property markets. Our findings on the relationship between market-to-book ratios and AREIT returns depart from standard finance literature. In comparison to REITs in other countries, AREITs have shifted their preferences away from property-type diversification and into more specialised investment strategies. We also find contrasting evidence on the impact of international diversification, and that domestic AREITs provide better returns than internationally diversified counterparts. The relationship between returns and short term interest rates was found to be positive and significant prior to 2002, and the relationship with long-term interest rates was found to be negative and significant since 2003, suggesting that AREITs exhibit less bond-like characteristics in the past five years.AREITs, AREIT returns, Property-type diversification, International diversification, Panel regressions

    A smart environment for biometric capture

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    The development of large scale biometric systems require experiments to be performed on large amounts of data. Existing capture systems are designed for fixed experiments and are not easily scalable. In this scenario even the addition of extra data is difficult. We developed a prototype biometric tunnel for the capture of non-contact biometrics. It is self contained and autonomous. Such a configuration is ideal for building access or deployment in secure environments. The tunnel captures cropped images of the subject's face and performs a 3D reconstruction of the person's motion which is used to extract gait information. Interaction between the various parts of the system is performed via the use of an agent framework. The design of this system is a trade-off between parallel and serial processing due to various hardware bottlenecks. When tested on a small population the extracted features have been shown to be potent for recognition. We currently achieve a moderate throughput of approximate 15 subjects an hour and hope to improve this in the future as the prototype becomes more complete

    Positron annihilation induced Auger electron spectroscopy

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    Recently, Weiss et al. have demonstrated that it is possible to excite Auger transitions by annihilating core electrons using a low energy (less than 30eV) beam of positrons. This mechanism makes possible a new electron spectroscopy, Positron annihilation induced Auger Electron Spectroscopy (PAES). The probability of exciting an Auger transition is proportional to the overlap of the positron wavefunction with atomic core levels. Since the Auger electron energy provides a signature of the atomic species making the transition, PAES makes it possible to determine the overlap of the positron wavefunction with a particular element. PAES may therefore provide a means of detecting positron-atom complexes. Measurements of PAES intensities from clean and adsorbate covered Cu surfaces are presented which indicate that approx. 5 percent of positrons injected into CU at 25eV produce core annihilations that result in Auger transitions

    Reply to "Comment on `First-principles calculation of the superconducting transition in MgB2 within the anisotropic Eliashberg formalism'"

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    The recent preprint by Mazin et al. [cond-mat/0212417] contains many inappropriate evaluations and/or criticisms on our published work [Phys. Rev. B 66, 020513 (2002) and Nature 418, 758 (2002)]. The preprint [cond-mat/0212417v1] was submitted to Physical Review B as a comment on one of our papers [Phys. Rev. B 66, 020513 (2002)]. In the reviewing process, Mazin et al. have withdrawn many of the statements contained in cond-mat/0212417v1, however two claims remain in their revised manuscript [cond-mat/0212417v3]: (1) the calculated variations of the superconducting energy gap within the sigma- or the pi-bands are not observable in real samples due to scatterings, and (2) the Coulomb repulsion mu(k,k') is negligibly small between sigma- and pi-states and thus should be approximated by a diagonal 2 x 2 matrix in the sigma and pi channels. Here, we point out that the former does not affect the validity of our theoretical work which is for the clean limit, and that the latter is not correct
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