55 research outputs found
Understanding Return And Volatility Spillovers Among Major Agricultural Commodities
We provide comprehensive evidence of return and volatility spillovers for the four major agricultural commodities including sugar, wheat, corn and cotton over the recent period 2003-2010. Our results from the recent VAR-GARCH model of Ling and McAleer (2003) that allows for simultaneous shock transmissions of conditional volatilities of returns across commodities show the existence of substantial volatility spillover linkages between agricultural commodity returns and volatilities. Our findings are also particularly insightful for optimal portfolio designs and risk management through the computation of optimal weights and hedge ratios
Per os infectivity of white spot syndrome virus (WSSV) in white-legged shrimp (Litopenaeus vannamei) and role of peritrophic membrane
As earlier observations on peroral infectivity of WSSV in white-legged shrimp are conflicting, here, a standardized peroral intubation technique was used to examine (i) the role of the physical composition of the viral inoculum and (ii) the barrier function of the PM. In a first experiment, the infectivity of a WSSV stock was compared by determining the SID50 by intramuscular injection, peroral inoculation or via feeding. The following titers were obtained: 108.77 SID50/g by intramuscular injection, 10(1.23) SID50/g by peroral inoculation and 100.73 SID50/g by feeding. These results demonstrated that 10(7.54)-10(8.03) infectious virus is needed to infect shrimp by peroral inoculation and via feeding. Next, it was examined if damage of the PM may increase the susceptibility for WSSV by peroral route. The infectivity of a virus stock was tested upon peroral inoculation of shrimp with and without removal of the PM and compared with the infectivity upon intramuscular inoculation. The virus titers obtained upon intramuscular injection and peroral inoculation of shrimp with and without PM were 10(8.63), 10(1.13) and 10(1.53) SID50/mL, respectively. This experiment confirmed the need of 10(7.1)-10(7.5) infectious virus to infect shrimp via peroral route and showed that the removal of the PM slightly but not significantly (p > 0.05) facilitated the infection of shrimp. This study indicated that WSSV contaminated feed is poorly infectious via peroral route, whereas it is highly infectious when injected into shrimp. The PM plays a minor role as internal barrier of shrimp against WSSV infection
Does The Glass Ceiling Exist? A Longitudinal Study Of Womens Progress On French Corporate Boards
n this article, we conduct a longitudinal study of womens progress on French corporate boards of directors. We particularly focus on the extent to which women directors have circumvented the glass ceiling. Using a sample of SBF 120 companies over a 10-year period from 2000 to 2009, our results provide evidence of a significant increase in the number of women on French corporate boards. However, the corporate glass ceiling hypothesis is consistently rejected whatever the considered measure of female directors; i.e., the number of board seats held by women, the number of firms with a critical mass of female directors, and the number of directorships held by each women director
Combination of Domain Knowledge and Deep Learning for Sentiment Analysis of Short and Informal Messages on Social Media
Sentiment analysis has been emerging recently as one of the major natural
language processing (NLP) tasks in many applications. Especially, as social
media channels (e.g. social networks or forums) have become significant sources
for brands to observe user opinions about their products, this task is thus
increasingly crucial. However, when applied with real data obtained from social
media, we notice that there is a high volume of short and informal messages
posted by users on those channels. This kind of data makes the existing works
suffer from many difficulties to handle, especially ones using deep learning
approaches. In this paper, we propose an approach to handle this problem. This
work is extended from our previous work, in which we proposed to combine the
typical deep learning technique of Convolutional Neural Networks with domain
knowledge. The combination is used for acquiring additional training data
augmentation and a more reasonable loss function. In this work, we further
improve our architecture by various substantial enhancements, including
negation-based data augmentation, transfer learning for word embeddings, the
combination of word-level embeddings and character-level embeddings, and using
multitask learning technique for attaching domain knowledge rules in the
learning process. Those enhancements, specifically aiming to handle short and
informal messages, help us to enjoy significant improvement in performance once
experimenting on real datasets.Comment: A Preprint of an article accepted for publication by Inderscience in
IJCVR on September 201
Corporate Performance Of Privatized Firms In Vietnam
We investigate the impacts of state shareholding, corporate culture and employee commitment on corporate performance of privatized firms in the Vietnamese context. Using data collected from a structured questionnaire as well as companies’ annual reports, we show that only organizational integration significantly affects the performance of privatized firms. Furthermore, employee and customer satisfactions are among the most important drivers of corporate performance. Finally, there is evidence to suggest that privatized firms with less state ownership perform better than those with more state ownership
Evaluating the effect of self-interference on the performance of full-duplex two-way relaying communication with energy harvesting
In this paper, we study the throughput and outage probability (OP) of two-way relaying (TWR) communication system with energy harvesting (EH). The system model consists two source nodes and a relay node which operates in full-duplex (FD) mode. The effect of self-interference (SI) due to the FD operation on the system performance is evaluated for both one-way full duplex (OWFD) and two-way full duplex (TWFD) diagrams where the amplify-and-forward (AF) relay node collects energy harvesting with the time switching (TS) scheme. We first propose an individual OP expression for each specific source. Then, we derive the exact closed-form overall OP expression for the OWFD diagram. For the TWFD diagram, we propose an approximate closed-form expression for the overall OP. The overall OP comparison among hybrid systems (Two-Way Half-Duplex (TWHD), OWFD, TWFD) are also discussed. Finally, the numerical/simulated results are presented for Rayleigh fading channels to demonstrate the correction of the proposed analysis
On The Performance of Underlay Relay Cognitive Networks
The bit error rate (BER) performance of underlay relay cognitive networks in the presence of Rayleigh fading is thoroughly analyzed in this paper. New exact and asymptotic analytic expressions under consideration of both interference power constraint and maximum transmit power constraint are derived in closed-form and are extensively corroborated by Monte-Carlo simulations. These expressions facilitate in evaluating effectively the network performance behaviour in key operation parameters as well as in optimizing system parameters. A multitude of analytical results expose that underlay relay cognitive networks experience the performance saturation phenomena while their performance considerably depends on the number of hops for the linear network model. Additionally, optimum relay position is significantly dependent of maximum transmit power, maximum interference power, and licensee location. Moreover, the appropriate order of locating unlicensees with different maximum transmit power levels can dramatically improve the network performance
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