Giap Nguyen - Academia.edu (original) (raw)

Papers by Giap Nguyen

An aggregate seafood import demand function for selected Caribbean countries is estimated using A... more An aggregate seafood import demand function for selected Caribbean countries is estimated using Autoregressive Error model and a Generalized Autoregressive Conditional Heteroscedasticity model to correct autocorrelation and heteroscedasticity. The results show that aggregated seafood import is elastic (-1.12), low-valued import is more elastic (-1.21), but high-valued import is inelastic (-0.72). Exchange rate has a negative effect on seafood import quantity. Income is not a factor in Caribbean seafood imports. Tourism has a positive impact on seafood imports. Seafood imports have a negative effect on domestic fisheries production, and a price increase is important in stimulating domestic fish production. Caribbean policy makers must be careful in articulating policies to encourage domestic production since increases in prices through a tariff may have differential effects on consumer groups.

Cointegration analysis and an Error Correction Model are used to estimate aggregate seafood impor... more Cointegration analysis and an Error Correction Model are used to estimate aggregate seafood import demand functions for selected Caribbean countries. The results show that seafood import demand is price elastic. Exchange rate has a negative effect on seafood import quantity. Income and tourist arrivals have positive impacts on seafood imports. Seafood import negatively affects domestic fishery production. Tariff and production support policies reduce seafood imports, and enhance domestic production. Both policies increase producer surplus, but a tariff reduces consumer surplus, and a production expansion policy increases consumer surplus. A production expansion subsidy is a more appropriate policy instrument than a tariff for small open economies, like the Caribbean States, to increase domestic production and generate net economic surplus.

Advances in Management and Applied Economics, 2013

We investigate the effects of food imports on the prevalence of obesity in selected LAC countries... more We investigate the effects of food imports on the prevalence of obesity in selected LAC countries. Cross sectional data for 25 selected LAC countries for the year 2002 were collected. Regression analyses with a semi-log functional form were developed to investigate whether food imports and other socio-economic variables influenced the prevalence of total population, male and female obesity. Total obesity model had an adjusted R2 of 0.72. Total food imports and gross national product per capita negatively influenced the prevalence of total obesity in net food importing countries (NFICs) whereas the total number of television sets had a positive effect. NFICs had a lower prevalence of obesity. For female obesity the equation had an adjusted R2 of 0.52. Food imports negatively influenced the prevalence of female obesity in NFICs, whereas gross national income per capita and the total number of television sets had positive effects. For male obesity, the equation had an adjusted R2 of 0....

Journal of food distribution research, 2013

Understanding supermarket sales of crawfish and potential competing crustacean products has the p... more Understanding supermarket sales of crawfish and potential competing crustacean products has the potential to assist the crawfish industry to refine its marketing strategies. A.C. Nielsen scanner data were used to develop a descriptive sales analysis of crawfish and competing crustacean product markets. Market shares, market trends and price fluctuations for different product forms of crawfish, crab, shrimp and lobster are presented for the period of 2005-2010. Markets for crawfish and competing products are described for different cities in the U.S. Discussions of potential effects of market specific demographics on consumption of crawfish and competing crustacean products are included.

Porcine circovirus 4 (PCV4), a novel and unclassified member of the genus Circovirus, was first r... more Porcine circovirus 4 (PCV4), a novel and unclassified member of the genus Circovirus, was first reported in China in 2019. Aimed at providing more evidence about the active circulation of PCV4, this study screened 335 pooled internal organs and detected the virus (i) at the rates of 3.28%, (ii) from both clinical healthy and clinical sick pigs of various age groups, and (iii) in six out of nice provinces of Korea. The complete genomic sequence of a Korean PCV4 strain (E115) was 1,770 nucleotides in length and had 98.5% to 98.9% identity to three PCV4 strains available at GenBank up to date. Utilizing a set of bioinformatic programs, it was revealed that the Korean PCV4 strain contained several genomic features of (i) a palindrome stem-loop structure with conserved nonanucleotide, (ii) packed overlapping ORFs oriented in different directions, and (iii) two intergenic regions in between genes encoding putative replication-associated protein (Rep) and capsid (Cap) proteins. This study also predicted the presence of essential elements known so far for the replication of circoviruses, for example, the origin of DNA replication, endonuclease and helicase domains of Rep, the nuclear localization signal on the putative Cap protein. Finally, based on the phylogeny inferred from sequences of the putative Rep protein, it was suggested that PCV4 belong to genus Circovirus of family Circoviridae and losely related to three previous known porcine circoviruses of PCV1, PCV2 and PCV3.

Multimedia Tools and Applications, 2017

Locality-preserving (distance preserving-mapping) is a useful property to manage multidimensional... more Locality-preserving (distance preserving-mapping) is a useful property to manage multidimensional data. Close points in space remain-as much as possible-close after mapping on curve. That is why Hilbert space-filling curve is used in many domains and applications. Hilbert curve preserves well locality because from a construction aspect, it is guided by adajacency constraint on points ordering : the curve connects all points of a Ddimensional discrete space, without favoring any direction, under the constrainst that two successive points are separated by an unit distance. Originally defined in 2-D, all existing multidimensional extensions of the Hilbert curve satisfy adjacency by using the RBG pattern (based on Reflected Binary Gray code). The RBG pattern is then duplicated and arranged (geometrical transformations) to build the multidimensional Hilbert curve at a given order. In this paper, we emphasize that there are other patterns that can satisfy the adjacency. A formulation is given, an algorithm to find out solutions is provided and their respective level of locality preservation is estimated through a standard criterion. Results show that some new patterns can carry a comparable levels of locality and sometimes better than RBG. Moreover, selecting the best locality preserving pattern allows one to design, through orders, a new curve with a comparable overall locality preserving refer to Hilbert curve. The contribution of new patterns is experimented through a CBIR (Content-Based Image Retrieval) application. Large-scale image retrieval tests show that exploring the image feature space with an alternative way to the classical Hilbert curve can lead to improved image searching performances.

The present study employs a cointegration method and error correction model to analyze the long-r... more The present study employs a cointegration method and error correction model to analyze the long-run relationship and short-run adjustment of aggregated seafood import demand function for selected Caribbean countries. The results show that there exists a long-term equilibrium relationship between Caribbean seafood import and related factors. Import demand elasticity is 1.72. Exchange rate has negative an effect on seafood imports, a one percent increase in exchange rate causes 1.55 percent decrease in seafood imports. Income has positive effect on seafood imports; a one percent income increase causes seafood imports to increase 0.22 percent. Tourist arrivals have positive effects on seafood imports, a one percent increase in tourist revenue cause 1.17 percent increase in seafood imports. Seafood imports have a significant negative effect on domestic fisheries production. The study suggests an outward shift of world seafood supply in the Caribbean region. The shift causes import price to decrease, and domestic seafood production to decrease as well. A tariff policy and a supply expansion both reduce imports, and enhance domestic production and producers' surplus. However, tariff policy reduces consumer surplus, while supply expansion increase consumer surplus.

A theoretical model links price risks at processors market to farm supply response. Price risks a... more A theoretical model links price risks at processors market to farm supply response. Price risks at wholesale market affect processors‚ factor demand for farm-raised catfish. The fluctuation in factor demand also influence the farm-raised catfish supply response. Price risks at wholesale market reduce processors‚ factor demand for farm-raised catfish, and in-turn have effects on catfish farm supply. The empirical results show evidences that price risks at wholesale market level reduces catfish farm supply. In terms of product forms, fillets have positive effects on farm supply, while whole fish have negative a relationship with farm supply. To completely understand the effects of risks at the processor level on farm supply further analyses of product diversification and its effects on processing and farm market are needed; factor demand and farm supply should be placed in a market equilibrium framework to thoroughly analyze the effects of factor demand shocks on farm-raised catfish supply response.

Ophthalmic Epidemiology, 2016

To assess validity of teacher-based vision screening and elicit factors associated with accuracy ... more To assess validity of teacher-based vision screening and elicit factors associated with accuracy of vision screening in Vietnam. After brief training, teachers independently measured visual acuity (VA) in 555 children aged 12-15 years in Ba Ria - Vung Tau Province. Teacher VA measurements were compared to those of refractionists. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for uncorrected VA (UVA) and presenting VA (PVA) 20/40 or worse in either eye. Chi-square, Fisher's exact test and multivariate logistic regression were used to assess factors associated with accuracy of vision screening. Level of significance was set at 5%. Trained teachers in Vietnam demonstrated 86.7% sensitivity, 95.7% specificity, 86.7% positive predictive value and 95.7% negative predictive value in identifying children with visual impairment using the UVA measurement. PVA measurement revealed low accuracy for teachers, which was significantly associated with child's age, sex, spectacle wear and myopic status, but UVA measurement showed no such associations. Better accuracy was achieved in measurement of VA and identification of children with visual impairment using UVA measurement compared to PVA. UVA measurement is recommended for teacher-based vision screening programs.

The use of high-dimension features is unavoidable in many applications of image retrieval and tec... more The use of high-dimension features is unavoidable in many applications of image retrieval and techniques of dimension reductions are not always efficient. The space-filling curve reduces the number of dimensions to one while preserving the neighborhood relation. In this paper, Hilbert curve, the most neighborhood preserving space-filling curve, is used in shape retrieval. The retrieving is accelerated by ordering the shapes in 1-D dynamical data structure, which enables rapid insertions of new images without changing existing data. A proposal of fast mapping facilitate the computing of 1-D Hilbert indexes from high dimensional features.

Computer and Information Sciences III, 2012

In image retrieval, high-dimensional features lead often to good results, however, their uses in ... more In image retrieval, high-dimensional features lead often to good results, however, their uses in indexing and searching are time-consuming. The space-filling curve that reduces the number of dimensions to one while preserving the neighborhood relation can be used in this context. A new fast technique for image indexing is developed which enables rapid insertions of new images without changing existing data. The retrieving is accelerated by avoiding the distance computing because images are ordered on 1-D data structure. Hilbert curve, the most neighborhood preserving space-filling curve, is used in the experimentation. A proposal of fast mapping facilitates the computing of 1-D Hilbert indexes from high dimensional features.

2010 2nd International Conference on Image Processing Theory, Tools and Applications, 2010

Virus Genes, 2010

Porcine hemagglutinating encephalomyelitis virus (PHEV) causes vomiting and wasting disease (VWD)... more Porcine hemagglutinating encephalomyelitis virus (PHEV) causes vomiting and wasting disease (VWD) or encephalomyelitis, and primarily affects pigs under 3 weeks of age. In this study, we detected PHEV from clinically ill pigs in conventional pig farms in South Korea. From November 2009 to March 2010, a total of 239 pig tissue samples from 91 farms were tested by nested RT-PCR. Among 239 samples, 22 samples from 17 farms were positive for PHEV. The detection rate of suckling pigs, weaning pigs, growers and finishers were 14.3% (12/84), 6.5% (7/107), 7% (3/43), and 0% (0/5), respectively. Symptoms were neurological, respiratory, enteric sign (diarrhea), or nasal bleeding. All pigs were co-infected with other viruses and bacteria and this might have resulted in age variation and clinical signs in the affected pigs. Phylogenetic analysis showed that the PHEV-positive samples and PHEV reference strains were clustered in the same group. These findings imply the presence of only one genogroup of PHEV, regardless of porcine age, clinical signs, and geographical location.

Traitement du signal, 2012

,jean-marc.ogier}@univ-lr.fr RÉSUMÉ. Les courbes remplissant l'espace sont largement utilisées da... more ,jean-marc.ogier}@univ-lr.fr RÉSUMÉ. Les courbes remplissant l'espace sont largement utilisées dans plusieurs domaines de l'informatique où la conservation de la localité est souvent considérée comme le critère pour choisir le type de courbe opérant dans une application. C'est pourquoi, la courbe de Hilbert, en qualité de courbe préservant au mieux la localité, reste majoritairement employée. Cependant, existe-t-il d'autres courbes vérifiant un niveau de localité comparable à la courbe de Hilbert ? Dans cet article, nous proposons une méthode flexible permettant de construire une famille de courbes-remplissant un espace multidimensionnel-de niveau de localité comparable à la courbe de Hilbert et parfois meilleur. Des tests expérimentaux comparatifs tendent à confirmer ces résultats. Notons que des éléments de preuve sur la validité de notre proposition sont avancés, sa mise en oeuvre est illustrée à travers de nombreux exemples. ABSTRACT. Space-filling curves are widely used in many fields of computer science in which the locality preserving is often seen as the criterion to select the curve type working in an application. This is why the Hilbert curve, as the best locality preserving curve, is mainly used. However, are there other curves who preserve the locality as well as to the Hilbert curve ? In this paper, we propose a flexible method for constructing a family of multidimensional spacefilling curves whose locality preserving level is comparable or better than that of the Hilbert curve. Comparative experimental tests tend to confirm these results. Note that the evidence on the validity of our proposal is advanced, its implementation is illustrated through numerous examples.

Marine Resource Economics, 2012

ABSTRACT A non-linear AIDS model was used to estimate substitution patterns across seafood catego... more ABSTRACT A non-linear AIDS model was used to estimate substitution patterns across seafood categories at the US retail market level. Results indicate that demand for catfish, crawfish, clams, and salmon products is elastic, suggesting that consumers are sensitive to price changes. In contrast, demand for shrimp and tilapia, mostly imported products, is price inelastic. US consumers would “tolerate” an increase in tilapia price compared to other seafood categories, especially catfish. Tilapia and salmon are found to have the most negative effects on purchases of other seafood products. Catfish is a strong substitute for tilapia; while tilapia is not a strong one for catfish. Promotions play significant roles in seafood purchases, especially among import-dominant products like shrimp, tilapia, and salmon. Future research should first be conducted at the metropolitan level, highlighting market specificity implied by consumers’ demographics; secondly, it should be done at disaggregated levels for each seafood category, product form, and product size.

Artificial Life and Robotics, 2008

Aquaculture Economics & Management, 2013

ABSTRACT Policy analysis matrices are developed and used to derive domestic resource cost coeffic... more ABSTRACT Policy analysis matrices are developed and used to derive domestic resource cost coefficients for different catfish farm production regions in the United States. The results show that U.S. catfish producers were losing their comparative advantage positions during the study period considered. An import tariff improves the industry's comparative advantage position, but may not increase its market profitability. Higher efficiency in feed usage, and higher market prices paid to producers through promotional efforts are essential to the U.S. catfish industry.

Aquaculture Economics & Management, 2013

ABSTRACT This study used a LA/AIDS model to estimate demand system for crustacean species, shrimp... more ABSTRACT This study used a LA/AIDS model to estimate demand system for crustacean species, shrimp, crab, crawfish and lobster at the U.S. retail store level. Shrimp demand is price elastic; crab, crawfish and lobster are price inelastic. Shrimp price significantly affects market shares of crustacean products. Shrimp has more substitutes than other crustaceans, and lobster has less substitutes than others. The demand for crab and lobster grow faster than the demand for shrimp and crawfish when expenditure increases. Promotion has positive effects on market shares and sales volume of own products and negative effects on cross-products. Shrimp price-reduction promotion strategies will be effective in term of raising shrimp sales value. Marketing programs that increase consumers’ marginal utility with an additional small increase in the selling price of crab, crawfish and lobster products will be feasible, and bring higher sale values.

An aggregate seafood import demand function for selected Caribbean countries is estimated using A... more An aggregate seafood import demand function for selected Caribbean countries is estimated using Autoregressive Error model and a Generalized Autoregressive Conditional Heteroscedasticity model to correct autocorrelation and heteroscedasticity. The results show that aggregated seafood import is elastic (-1.12), low-valued import is more elastic (-1.21), but high-valued import is inelastic (-0.72). Exchange rate has a negative effect on seafood import quantity. Income is not a factor in Caribbean seafood imports. Tourism has a positive impact on seafood imports. Seafood imports have a negative effect on domestic fisheries production, and a price increase is important in stimulating domestic fish production. Caribbean policy makers must be careful in articulating policies to encourage domestic production since increases in prices through a tariff may have differential effects on consumer groups.

Cointegration analysis and an Error Correction Model are used to estimate aggregate seafood impor... more Cointegration analysis and an Error Correction Model are used to estimate aggregate seafood import demand functions for selected Caribbean countries. The results show that seafood import demand is price elastic. Exchange rate has a negative effect on seafood import quantity. Income and tourist arrivals have positive impacts on seafood imports. Seafood import negatively affects domestic fishery production. Tariff and production support policies reduce seafood imports, and enhance domestic production. Both policies increase producer surplus, but a tariff reduces consumer surplus, and a production expansion policy increases consumer surplus. A production expansion subsidy is a more appropriate policy instrument than a tariff for small open economies, like the Caribbean States, to increase domestic production and generate net economic surplus.

Advances in Management and Applied Economics, 2013

We investigate the effects of food imports on the prevalence of obesity in selected LAC countries... more We investigate the effects of food imports on the prevalence of obesity in selected LAC countries. Cross sectional data for 25 selected LAC countries for the year 2002 were collected. Regression analyses with a semi-log functional form were developed to investigate whether food imports and other socio-economic variables influenced the prevalence of total population, male and female obesity. Total obesity model had an adjusted R2 of 0.72. Total food imports and gross national product per capita negatively influenced the prevalence of total obesity in net food importing countries (NFICs) whereas the total number of television sets had a positive effect. NFICs had a lower prevalence of obesity. For female obesity the equation had an adjusted R2 of 0.52. Food imports negatively influenced the prevalence of female obesity in NFICs, whereas gross national income per capita and the total number of television sets had positive effects. For male obesity, the equation had an adjusted R2 of 0....

Journal of food distribution research, 2013

Understanding supermarket sales of crawfish and potential competing crustacean products has the p... more Understanding supermarket sales of crawfish and potential competing crustacean products has the potential to assist the crawfish industry to refine its marketing strategies. A.C. Nielsen scanner data were used to develop a descriptive sales analysis of crawfish and competing crustacean product markets. Market shares, market trends and price fluctuations for different product forms of crawfish, crab, shrimp and lobster are presented for the period of 2005-2010. Markets for crawfish and competing products are described for different cities in the U.S. Discussions of potential effects of market specific demographics on consumption of crawfish and competing crustacean products are included.

Porcine circovirus 4 (PCV4), a novel and unclassified member of the genus Circovirus, was first r... more Porcine circovirus 4 (PCV4), a novel and unclassified member of the genus Circovirus, was first reported in China in 2019. Aimed at providing more evidence about the active circulation of PCV4, this study screened 335 pooled internal organs and detected the virus (i) at the rates of 3.28%, (ii) from both clinical healthy and clinical sick pigs of various age groups, and (iii) in six out of nice provinces of Korea. The complete genomic sequence of a Korean PCV4 strain (E115) was 1,770 nucleotides in length and had 98.5% to 98.9% identity to three PCV4 strains available at GenBank up to date. Utilizing a set of bioinformatic programs, it was revealed that the Korean PCV4 strain contained several genomic features of (i) a palindrome stem-loop structure with conserved nonanucleotide, (ii) packed overlapping ORFs oriented in different directions, and (iii) two intergenic regions in between genes encoding putative replication-associated protein (Rep) and capsid (Cap) proteins. This study also predicted the presence of essential elements known so far for the replication of circoviruses, for example, the origin of DNA replication, endonuclease and helicase domains of Rep, the nuclear localization signal on the putative Cap protein. Finally, based on the phylogeny inferred from sequences of the putative Rep protein, it was suggested that PCV4 belong to genus Circovirus of family Circoviridae and losely related to three previous known porcine circoviruses of PCV1, PCV2 and PCV3.

Multimedia Tools and Applications, 2017

Locality-preserving (distance preserving-mapping) is a useful property to manage multidimensional... more Locality-preserving (distance preserving-mapping) is a useful property to manage multidimensional data. Close points in space remain-as much as possible-close after mapping on curve. That is why Hilbert space-filling curve is used in many domains and applications. Hilbert curve preserves well locality because from a construction aspect, it is guided by adajacency constraint on points ordering : the curve connects all points of a Ddimensional discrete space, without favoring any direction, under the constrainst that two successive points are separated by an unit distance. Originally defined in 2-D, all existing multidimensional extensions of the Hilbert curve satisfy adjacency by using the RBG pattern (based on Reflected Binary Gray code). The RBG pattern is then duplicated and arranged (geometrical transformations) to build the multidimensional Hilbert curve at a given order. In this paper, we emphasize that there are other patterns that can satisfy the adjacency. A formulation is given, an algorithm to find out solutions is provided and their respective level of locality preservation is estimated through a standard criterion. Results show that some new patterns can carry a comparable levels of locality and sometimes better than RBG. Moreover, selecting the best locality preserving pattern allows one to design, through orders, a new curve with a comparable overall locality preserving refer to Hilbert curve. The contribution of new patterns is experimented through a CBIR (Content-Based Image Retrieval) application. Large-scale image retrieval tests show that exploring the image feature space with an alternative way to the classical Hilbert curve can lead to improved image searching performances.

The present study employs a cointegration method and error correction model to analyze the long-r... more The present study employs a cointegration method and error correction model to analyze the long-run relationship and short-run adjustment of aggregated seafood import demand function for selected Caribbean countries. The results show that there exists a long-term equilibrium relationship between Caribbean seafood import and related factors. Import demand elasticity is 1.72. Exchange rate has negative an effect on seafood imports, a one percent increase in exchange rate causes 1.55 percent decrease in seafood imports. Income has positive effect on seafood imports; a one percent income increase causes seafood imports to increase 0.22 percent. Tourist arrivals have positive effects on seafood imports, a one percent increase in tourist revenue cause 1.17 percent increase in seafood imports. Seafood imports have a significant negative effect on domestic fisheries production. The study suggests an outward shift of world seafood supply in the Caribbean region. The shift causes import price to decrease, and domestic seafood production to decrease as well. A tariff policy and a supply expansion both reduce imports, and enhance domestic production and producers' surplus. However, tariff policy reduces consumer surplus, while supply expansion increase consumer surplus.

A theoretical model links price risks at processors market to farm supply response. Price risks a... more A theoretical model links price risks at processors market to farm supply response. Price risks at wholesale market affect processors‚ factor demand for farm-raised catfish. The fluctuation in factor demand also influence the farm-raised catfish supply response. Price risks at wholesale market reduce processors‚ factor demand for farm-raised catfish, and in-turn have effects on catfish farm supply. The empirical results show evidences that price risks at wholesale market level reduces catfish farm supply. In terms of product forms, fillets have positive effects on farm supply, while whole fish have negative a relationship with farm supply. To completely understand the effects of risks at the processor level on farm supply further analyses of product diversification and its effects on processing and farm market are needed; factor demand and farm supply should be placed in a market equilibrium framework to thoroughly analyze the effects of factor demand shocks on farm-raised catfish supply response.

Ophthalmic Epidemiology, 2016

To assess validity of teacher-based vision screening and elicit factors associated with accuracy ... more To assess validity of teacher-based vision screening and elicit factors associated with accuracy of vision screening in Vietnam. After brief training, teachers independently measured visual acuity (VA) in 555 children aged 12-15 years in Ba Ria - Vung Tau Province. Teacher VA measurements were compared to those of refractionists. Sensitivity, specificity, positive predictive value and negative predictive value were calculated for uncorrected VA (UVA) and presenting VA (PVA) 20/40 or worse in either eye. Chi-square, Fisher's exact test and multivariate logistic regression were used to assess factors associated with accuracy of vision screening. Level of significance was set at 5%. Trained teachers in Vietnam demonstrated 86.7% sensitivity, 95.7% specificity, 86.7% positive predictive value and 95.7% negative predictive value in identifying children with visual impairment using the UVA measurement. PVA measurement revealed low accuracy for teachers, which was significantly associated with child's age, sex, spectacle wear and myopic status, but UVA measurement showed no such associations. Better accuracy was achieved in measurement of VA and identification of children with visual impairment using UVA measurement compared to PVA. UVA measurement is recommended for teacher-based vision screening programs.

The use of high-dimension features is unavoidable in many applications of image retrieval and tec... more The use of high-dimension features is unavoidable in many applications of image retrieval and techniques of dimension reductions are not always efficient. The space-filling curve reduces the number of dimensions to one while preserving the neighborhood relation. In this paper, Hilbert curve, the most neighborhood preserving space-filling curve, is used in shape retrieval. The retrieving is accelerated by ordering the shapes in 1-D dynamical data structure, which enables rapid insertions of new images without changing existing data. A proposal of fast mapping facilitate the computing of 1-D Hilbert indexes from high dimensional features.

Computer and Information Sciences III, 2012

In image retrieval, high-dimensional features lead often to good results, however, their uses in ... more In image retrieval, high-dimensional features lead often to good results, however, their uses in indexing and searching are time-consuming. The space-filling curve that reduces the number of dimensions to one while preserving the neighborhood relation can be used in this context. A new fast technique for image indexing is developed which enables rapid insertions of new images without changing existing data. The retrieving is accelerated by avoiding the distance computing because images are ordered on 1-D data structure. Hilbert curve, the most neighborhood preserving space-filling curve, is used in the experimentation. A proposal of fast mapping facilitates the computing of 1-D Hilbert indexes from high dimensional features.

2010 2nd International Conference on Image Processing Theory, Tools and Applications, 2010

Virus Genes, 2010

Porcine hemagglutinating encephalomyelitis virus (PHEV) causes vomiting and wasting disease (VWD)... more Porcine hemagglutinating encephalomyelitis virus (PHEV) causes vomiting and wasting disease (VWD) or encephalomyelitis, and primarily affects pigs under 3 weeks of age. In this study, we detected PHEV from clinically ill pigs in conventional pig farms in South Korea. From November 2009 to March 2010, a total of 239 pig tissue samples from 91 farms were tested by nested RT-PCR. Among 239 samples, 22 samples from 17 farms were positive for PHEV. The detection rate of suckling pigs, weaning pigs, growers and finishers were 14.3% (12/84), 6.5% (7/107), 7% (3/43), and 0% (0/5), respectively. Symptoms were neurological, respiratory, enteric sign (diarrhea), or nasal bleeding. All pigs were co-infected with other viruses and bacteria and this might have resulted in age variation and clinical signs in the affected pigs. Phylogenetic analysis showed that the PHEV-positive samples and PHEV reference strains were clustered in the same group. These findings imply the presence of only one genogroup of PHEV, regardless of porcine age, clinical signs, and geographical location.

Traitement du signal, 2012

,jean-marc.ogier}@univ-lr.fr RÉSUMÉ. Les courbes remplissant l'espace sont largement utilisées da... more ,jean-marc.ogier}@univ-lr.fr RÉSUMÉ. Les courbes remplissant l'espace sont largement utilisées dans plusieurs domaines de l'informatique où la conservation de la localité est souvent considérée comme le critère pour choisir le type de courbe opérant dans une application. C'est pourquoi, la courbe de Hilbert, en qualité de courbe préservant au mieux la localité, reste majoritairement employée. Cependant, existe-t-il d'autres courbes vérifiant un niveau de localité comparable à la courbe de Hilbert ? Dans cet article, nous proposons une méthode flexible permettant de construire une famille de courbes-remplissant un espace multidimensionnel-de niveau de localité comparable à la courbe de Hilbert et parfois meilleur. Des tests expérimentaux comparatifs tendent à confirmer ces résultats. Notons que des éléments de preuve sur la validité de notre proposition sont avancés, sa mise en oeuvre est illustrée à travers de nombreux exemples. ABSTRACT. Space-filling curves are widely used in many fields of computer science in which the locality preserving is often seen as the criterion to select the curve type working in an application. This is why the Hilbert curve, as the best locality preserving curve, is mainly used. However, are there other curves who preserve the locality as well as to the Hilbert curve ? In this paper, we propose a flexible method for constructing a family of multidimensional spacefilling curves whose locality preserving level is comparable or better than that of the Hilbert curve. Comparative experimental tests tend to confirm these results. Note that the evidence on the validity of our proposal is advanced, its implementation is illustrated through numerous examples.

Marine Resource Economics, 2012

ABSTRACT A non-linear AIDS model was used to estimate substitution patterns across seafood catego... more ABSTRACT A non-linear AIDS model was used to estimate substitution patterns across seafood categories at the US retail market level. Results indicate that demand for catfish, crawfish, clams, and salmon products is elastic, suggesting that consumers are sensitive to price changes. In contrast, demand for shrimp and tilapia, mostly imported products, is price inelastic. US consumers would “tolerate” an increase in tilapia price compared to other seafood categories, especially catfish. Tilapia and salmon are found to have the most negative effects on purchases of other seafood products. Catfish is a strong substitute for tilapia; while tilapia is not a strong one for catfish. Promotions play significant roles in seafood purchases, especially among import-dominant products like shrimp, tilapia, and salmon. Future research should first be conducted at the metropolitan level, highlighting market specificity implied by consumers’ demographics; secondly, it should be done at disaggregated levels for each seafood category, product form, and product size.

Artificial Life and Robotics, 2008

Aquaculture Economics & Management, 2013

ABSTRACT Policy analysis matrices are developed and used to derive domestic resource cost coeffic... more ABSTRACT Policy analysis matrices are developed and used to derive domestic resource cost coefficients for different catfish farm production regions in the United States. The results show that U.S. catfish producers were losing their comparative advantage positions during the study period considered. An import tariff improves the industry's comparative advantage position, but may not increase its market profitability. Higher efficiency in feed usage, and higher market prices paid to producers through promotional efforts are essential to the U.S. catfish industry.

Aquaculture Economics & Management, 2013

ABSTRACT This study used a LA/AIDS model to estimate demand system for crustacean species, shrimp... more ABSTRACT This study used a LA/AIDS model to estimate demand system for crustacean species, shrimp, crab, crawfish and lobster at the U.S. retail store level. Shrimp demand is price elastic; crab, crawfish and lobster are price inelastic. Shrimp price significantly affects market shares of crustacean products. Shrimp has more substitutes than other crustaceans, and lobster has less substitutes than others. The demand for crab and lobster grow faster than the demand for shrimp and crawfish when expenditure increases. Promotion has positive effects on market shares and sales volume of own products and negative effects on cross-products. Shrimp price-reduction promotion strategies will be effective in term of raising shrimp sales value. Marketing programs that increase consumers’ marginal utility with an additional small increase in the selling price of crab, crawfish and lobster products will be feasible, and bring higher sale values.