Feeding profile of Mepraia spinolai, a sylvatic vector of Chagas disease in Chile.
Chacón, F; Bacigalupo, A; Quiroga, J F; Ferreira, A; Cattan, P E; Ramírez-Toloza, G
2016-10-01
American trypanosomiasis is a chronic disease transmitted mainly by vectors. The hematophagous triatomine vectors transmit Trypanosoma cruzi to a wide variety of mammals, which usually are their food source. This study determined the feeding profile of Mepraia spinolai, a sylvatic triatomine vector, present in endemic areas of Chile. Vectors were captured in the north-central area of Chile. Samples of intestinal contents were analyzed by an Enzyme-linked immunosorbent assay (ELISA) that identifies and discriminates the presence of serum antigens from Homo sapiens and nine animal species (Canis familiaris, Felis catus, Capra hircus, Mus musculus, Gallus gallus, Octodon degus, Thylamys elegans, Phyllotis darwini and Oryctolagus cuniculus). Our data indicate the most frequent feeding source in this area was P. darwini, followed by O. degus, O. cuniculus, M. musculus, G. gallus, T. elegans, C. familiaris, F. catus and C. hircus. Mixed food sources were also identified.
Frías-Lasserre, Daniel; González, Christian R; Valenzuela, Carolina Reyes; de Carvalho, Danila Blanco; Oliveira, Jader; Canals, Mauricio; da Rosa, Joao Aristeu
2017-03-24
Mepraia spinolai (Porter) is a vector of Trypanosoma cruzi that causes Chagas disease. Females are always wingless, but males may be winged or wingless. We determined by PCR the infection percentage with T. cruzi of M. spinolai adults and nymphs in domestic, peridomestic, and wild collections, in different regions of Chile. In all regions, winged males were more abundant than females and wingless males. Winged males collected inside houses were less parasitized than were those from peridomestic and wild environments. Although winged males of M. spinolai have comparatively low levels of infection, this segment may still represent the greatest vector threat in this species for transmission of T. cruzi to humans and other vertebrates in domestic, wild, and peridomestic habitats. Winged males represent the dispersive form of this species that invades human dwellings. Feeding deprivation resulting from the time required to find a food source and to search for reproductive females could explain the lower infection rates (negatives) of winged males collected from inside houses in comparison with winged males collected from peridomestic and wild habitats. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Egaña, Camila; Pinto, Raquel; Vergara, Fernanda; Ortiz, Sylvia; Campos, Ricardo; Solari, Aldo
2016-08-01
Mepraia species are hematophagous insects and the most important wild vectors of Trypanosoma cruzi, the causative agent of Chagas disease in southeastern South America. Because the domestic Triatoma infestans is already controlled, the transmission of different T. cruzi discrete typing units (DTUs) by Mepraia species deserves attention. Our aim is to gather information on the diversity of T. cruzi DTUs circulating in natural insect populations. Two groups of naturally infected bugs 21 Mepraia gajardoi and 26 Mepraia spinolai were followed-up after two or more laboratory feedings by means of minicircle-PCR assays to evaluate the composition of four T. cruzi DTUs by hybridization tests. Fluctuations from positive T. cruzi detection to negative and the converse, as well as single to mixed infections with different T. cruzi DTUs and the opposite were frequent observations after laboratory feeding in both Mepraia species. Single and mixed infections with more than two T. cruzi DTUs were detected after the first feeding; however mainly mixed infections prevailed after the second feeding. Laboratory feeding on three or more occasions resulted in a decreasing trend of the parasite burden. In a comparison with 28 infected and fed M. gajardoi collected one year before from the same vector colony T. cruzi DTUs composition changed, indicating that temporal variations occur in T. cruzi. Natural populations of Mepraia species can transmit complex mixtures T. cruzi DTUs which fluctuate over time after feeding, with a tendency to eliminate the parasitism after prolonged feeding. Copyright © 2016 Elsevier B.V. All rights reserved.
Campos-Soto, Ricardo; Ortiz, Sylvia; Cordova, Ivan; Bruneau, Nicole; Botto-Mahan, Carezza; Solari, Aldo
2016-03-01
Chagas disease, which ranks among the world's most neglected diseases, is a chronic, systemic, parasitic infection caused by the protozoan Trypanosoma cruzi. Mepraia species are the wild vectors of this parasite in Chile. Host-parasite interactions can occur at several levels, such as co-speciation and ecological host fitting, among others. Thus, we are exploring the interactions between T. cruzi circulating in naturally infected Mepraia species in all areas endemic of Chile. We evaluated T. cruzi infection rates of 27 different haplotypes of the wild Mepraia species and identified their parasite genotypes using minicircle PCR amplification and hybridization tests with genotype-specific DNA probes. Infection rates were lower in northern Chile where Mepraia gajardoi circulates (10-35%); in central Chile, Mepraia spinolai is most abundant, and infection rates varied in space and time (0-55%). T. cruzi discrete typing units (DTUs) TcI, TcII, TcV, and Tc VI were detected. Mixed infections with two or more DTUs are frequently found in highly infected insects. T. cruzi DTUs have distinct, but not exclusive, ecological and epidemiological associations with their hosts. T. cruzi infection rates of M. spinolai were higher than in M. gajardoi, but the presence of mixed infection with more than one T. cruzi DTU was the same. The same T. cruzi DTUs (TcI, TcII, TcV, and TcVI) were found circulating in both vector species, even though TcI was not equally distributed. These results suggest that T. cruzi DTUs are not associated with any of the two genetically related vector species nor with the geographic area. The T. cruzi vectors interactions are discussed in terms of old and recent events. By exploring T. cruzi DTUs present in Mepraia haplotypes and species from northern to central Chile, we open the analysis on these invertebrate host-parasite interactions.
Campos, Ricardo; Torres-Pérez, Fernando; Botto-Mahan, Carezza; Coronado, Ximena; Solari, Aldo
2013-10-01
The hematophagous Hemiptera of the subfamily Triatominae are a very diverse group with a variety of morphs, behaviors and distributions. They have great epidemiological importance because many of its members are vectors of the protozoan Trypanosoma cruzi, the agent of Chagas disease. Mepraia is a genus of Triatominae endemic to Chile responsible for transmitting T. cruzi in the sylvatic cycle. Mepraia includes three species, M. gajardoi (18° 30'-26° 30' S) M. spinolai (26° 30'-34° 20' S) and the recently described M. parapatrica in intermediate zones (24° 36'-26° 51' S). Using mitochondrial DNA sequences, we inferred historical processes that led to the current structure of populations. Phylogeographic analyses identified three lineages, congruent with current taxonomy, and populations were highly structured. The times to the most recent common ancestor suggest that M. spinolai is the oldest lineage. We discuss the taxonomic and biogeographic implications of our results. Copyright © 2013 Elsevier B.V. All rights reserved.
Systematics of Mepraia (Hemiptera-Reduviidae): cytogenetic and molecular variation.
Calleros, L; Panzera, F; Bargues, M D; Monteiro, F A; Klisiowicz, D R; Zuriaga, M A; Mas-Coma, S; Pérez, R
2010-03-01
The haematophagous insects of the subfamily Triatominae (Hemiptera-Reduviidae) have great epidemiological importance as vectors of Trypanosoma cruzi, the causative agent of Chagas disease. Mepraia was originally described as a monotypic genus comprised of Mepraia spinolai, distributed along coastal areas of northern Chile (from Region I to the Metropolitan Region). Recently, some M. spinolai populations have been ranked as a new species named Mepraia gajardoi. Several populations along the distribution range of the genus were sampled, and genetic differentiation was studied based upon the analysis of three molecular markers: cytogenetics (karyotype and chromosome behaviour during meiosis using the C-banding technique), mitochondrial DNA (a cytochrome oxidase I gene fragment), and nuclear ribosomal DNA (intergenic region including the two internal transcribed spacers ITS-1 and ITS-2 and the 5.8S rRNA gene). The data here presented indicate that populations within the Mepraia genus (excluding Region II specimens) can be divided into two separate lineages. One lineage is comprised of specimens from the northernmost Region I and represents M. gajardoi. The other includes samples from the southern III, IV and the Metropolitan Regions, and represents M. spinolai. Region II individuals deserve particular attention as their relationship to the two identified lineages is not clear-cut. While they appear to belong to M. spinolai based on cytogenetics and rDNA markers, COI results indicate a closer relationship to M. gajardoi. This disagreement can be due to mitochondrial DNA introgression or the retention of ancestral polymorphisms.
Campos-Soto, Ricardo; Torres-Pérez, Fernando; Solari, Aldo
2015-01-01
Mitochondrial DNA (mtDNA) is widely used to clarify phylogenetic relationships among and within species, and to determine population structure. Due to the linked nature of mtDNA genes it is expected that different genes will show similar results. Phylogenetic incongruence using mtDNA genes may result from processes such as heteroplasmy, nuclear integration of mitochondrial genes, polymerase errors, contamination, and recombination. In this study we used sequences from two mitochondrial genes (cytochrome b and cytochrome oxidase subunit I) from the wild vectors of Chagas disease, Triatoma eratyrusiformis and Mepraia species to test for topological congruence. The results showed some cases of phylogenetic incongruence due to misplacement of four haplotypes of four individuals. We discuss the possible causes of such incongruence and suggest that the explanation is an intra-individual variation likely due to heteroplasmy. This phenomenon is an independent evidence of common ancestry between these taxa. PMID:26500444
Morphological Variation on Isolated Populations of Praocis (Praocis) spinolai
Benítez, Hugo A.; Pizarro-Araya, Jaime; Bravi, Raffaella; Sanzana, María-José; Alfaro, Fermín M.
2014-01-01
In this study, the morphological variations of four geographically isolated populations of Praocis (Praocis) spinolai Gay & Solier (Coleoptera: Tenebrionidae) in the transitional coastal desert, Chile, were studied. The study was conducted in the coastal area of Punta de Choros and Los Choros-Archipelago, which includes three islands: Choros, Damas, and Gaviota. 113 specimens of the species P. (P.) spinolai belonging to the four locations sampled were collected analyzed with geometric morphometrics techniques to explore the pattern of shape variation on the different isolated environments. The principal component analysis revealed a well-defined pattern of variation between the populations analyzed. Moreover, differences between populations emerged also from the canonical variation analysis and were confirmed by the Procrustes ANOVA. All analyses performed confirmed the existence of a pattern of variation, due to the isolation of the populations and to environmental effects. The islands are subject to more arid pressures than the continent, where there is a more stable environment and the presence of coastal wetlands and the coastal range of mountains act together and enable fog condensation. This study indicates the existence of a clear pattern of variation, which indicates an evolutionary trend among the population examined. PMID:25373158
Morphological variation on isolated populations of Praocis (Praocis) spinolai.
Benítez, Hugo A; Pizarro-Araya, Jaime; Bravi, Raffaella; Sanzana, María-José; Alfaro, Fermín M
2014-01-26
In this study, the morphological variations of four geographically isolated populations of Praocis (Praocis) spinolai Gay & Solier (Coleoptera: Tenebrionidae) in the transitional coastal desert, Chile, were studied. The study was conducted in the coastal area of Punta de Choros and Los Choros-Archipelago, which includes three islands: Choros, Damas, and Gaviota. 113 specimens of the species P. (P.) spinolai belonging to the four locations sampled were collected analyzed with geometric morphometrics techniques to explore the pattern of shape variation on the different isolated environments. The principal component analysis revealed a well-defined pattern of variation between the populations analyzed. Moreover, differences between populations emerged also from the canonical variation analysis and were confirmed by the Procrustes ANOVA. All analyses performed confirmed the existence of a pattern of variation, due to the isolation of the populations and to environmental effects. The islands are subject to more arid pressures than the continent, where there is a more stable environment and the presence of coastal wetlands and the coastal range of mountains act together and enable fog condensation. This study indicates the existence of a clear pattern of variation, which indicates an evolutionary trend among the population examined. This is an open access paper. We use the Creative Commons Attribution 3.0 license that permits unrestricted use, provided that the paper is properly attributed.
Spatial distribution of an infectious disease in a small mammal community.
Correa, Juana P; Bacigalupo, Antonella; Fontúrbel, Francisco E; Oda, Esteban; Cattan, Pedro E; Solari, Aldo; Botto-Mahan, Carezza
2015-10-01
Chagas disease is a zoonosis caused by the parasite Trypanosoma cruzi and transmitted by insect vectors to several mammals, but little is known about its spatial epidemiology. We assessed the spatial distribution of T. cruzi infection in vectors and small mammals to test if mammal infection status is related to the proximity to vector colonies. During four consecutive years we captured and georeferenced the locations of mammal species and colonies of Mepraia spinolai, a restricted-movement vector. Infection status on mammals and vectors was evaluated by molecular techniques. To examine the effect of vector colonies on mammal infection status, we constructed an infection distance index using the distance between the location of each captured mammal to each vector colony and the average T. cruzi prevalence of each vector colony, weighted by the number of colonies assessed. We collected and evaluated T. cruzi infection in 944 mammals and 1976 M. spinolai. We found a significant effect of the infection distance index in explaining their infection status, when considering all mammal species together. By examining the most abundant species separately, we found this effect only for the diurnal and gregarious rodent Octodon degus. Spatially explicit models involving the prevalence and location of infected vectors and hosts had not been reported previously for a wild disease.
Spatial distribution of an infectious disease in a small mammal community
NASA Astrophysics Data System (ADS)
Correa, Juana P.; Bacigalupo, Antonella; Fontúrbel, Francisco E.; Oda, Esteban; Cattan, Pedro E.; Solari, Aldo; Botto-Mahan, Carezza
2015-10-01
Chagas disease is a zoonosis caused by the parasite Trypanosoma cruzi and transmitted by insect vectors to several mammals, but little is known about its spatial epidemiology. We assessed the spatial distribution of T. cruzi infection in vectors and small mammals to test if mammal infection status is related to the proximity to vector colonies. During four consecutive years we captured and georeferenced the locations of mammal species and colonies of Mepraia spinolai, a restricted-movement vector. Infection status on mammals and vectors was evaluated by molecular techniques. To examine the effect of vector colonies on mammal infection status, we constructed an infection distance index using the distance between the location of each captured mammal to each vector colony and the average T. cruzi prevalence of each vector colony, weighted by the number of colonies assessed. We collected and evaluated T. cruzi infection in 944 mammals and 1976 M. spinolai. We found a significant effect of the infection distance index in explaining their infection status, when considering all mammal species together. By examining the most abundant species separately, we found this effect only for the diurnal and gregarious rodent Octodon degus. Spatially explicit models involving the prevalence and location of infected vectors and hosts had not been reported previously for a wild disease.
Cura, Carolina I.; Mejía-Jaramillo, Ana M.; Duffy, Tomás; Burgos, Juan M.; Rodriguero, Marcela; Cardinal, Marta V.; Kjos, Sonia; Gurgel-Gonçalves, Rodrigo; Blanchet, Denis; De Pablos, Luis M.; Tomasini, Nicolás; Silva, Alex Da; Russomando, Graciela; Cuba Cuba, Cesar A.; Aznar, Christine; Abate, Teresa; Levin, Mariano J.; Osuna, Antonio; Gürtler, Ricardo E.; Diosque, Patricio; Solari, Aldo; Triana-Chávez, Omar; Schijman, Alejandro G.
2011-01-01
The intergenic region of spliced-leader (SL-IR) genes from 105 Trypanosoma cruzi I (Tc I) infected biological samples, culture isolates and stocks from 11 endemic countries, from Argentina to the USA were characterised, allowing identification of 76 genotypes with 54 polymorphic sites from 123 aligned sequences. On the basis of the microsatellite motif proposed by Herrera et al. (2007) to define four haplotypes in Colombia, we could classify these genotypes into four distinct Tc I SL-IR groups, three corresponding to the former haplotypes Ia (11 genotypes), Ib (11 genotypes) and Id (35 genotypes); and one novel group, Ie (19 genotypes). Genotypes harboring the Tc Ic motif were not detected in our study. Tc Ia was associated with domestic cycles in southern and northern South America and sylvatic cycles in Central and North America. Tc Ib was found in all transmission cycles from Colombia. Tc Id was identified in all transmission cycles from Argentina and Colombia, including Chagas cardiomyopathy patients, sylvatic Brazilian samples and human cases from French Guiana, Panama and Venezuela. Tc Ie gathered five samples from domestic Triatoma infestans from northern Argentina, nine samples from wild Mepraia spinolai and Mepraia gajardoi and two chagasic patients from Chile and one from a Bolivian patient with chagasic reactivation. Mixed infections by Tc Ia + Tc Id, Tc Ia + Tc Ie and Tc Id + Tc Ie were detected in vector faeces and isolates from human and vector samples. In addition, Tc Ia and Tc Id were identified in different tissues from a heart transplanted Chagas cardiomyopathy patient with reactivation, denoting histotropism. Trypanosoma cruzi I SL-IR genotypes from parasites infecting Triatoma gerstaeckeri and Didelphis virginiana from USA, T. infestans from Paraguay, Rhodnius nasutus and Rhodnius neglectus from Brazil and M. spinolai and M. gajardoi from Chile are to our knowledge described for the first time. PMID:20670628
Cura, Carolina I; Mejía-Jaramillo, Ana M; Duffy, Tomás; Burgos, Juan M; Rodriguero, Marcela; Cardinal, Marta V; Kjos, Sonia; Gurgel-Gonçalves, Rodrigo; Blanchet, Denis; De Pablos, Luis M; Tomasini, Nicolás; da Silva, Alexandre; Russomando, Graciela; Cuba, Cesar A Cuba; Aznar, Christine; Abate, Teresa; Levin, Mariano J; Osuna, Antonio; Gürtler, Ricardo E; Diosque, Patricio; Solari, Aldo; Triana-Chávez, Omar; Schijman, Alejandro G
2010-12-01
The intergenic region of spliced-leader (SL-IR) genes from 105 Trypanosoma cruzi I (Tc I) infected biological samples, culture isolates and stocks from 11 endemic countries, from Argentina to the USA were characterised, allowing identification of 76 genotypes with 54 polymorphic sites from 123 aligned sequences. On the basis of the microsatellite motif proposed by Herrera et al. (2007) to define four haplotypes in Colombia, we could classify these genotypes into four distinct Tc I SL-IR groups, three corresponding to the former haplotypes Ia (11 genotypes), Ib (11 genotypes) and Id (35 genotypes); and one novel group, Ie (19 genotypes). Genotypes harbouring the Tc Ic motif were not detected in our study. Tc Ia was associated with domestic cycles in southern and northern South America and sylvatic cycles in Central and North America. Tc Ib was found in all transmission cycles from Colombia. Tc Id was identified in all transmission cycles from Argentina and Colombia, including Chagas cardiomyopathy patients, sylvatic Brazilian samples and human cases from French Guiana, Panama and Venezuela. Tc Ie gathered five samples from domestic Triatoma infestans from northern Argentina, nine samples from wild Mepraia spinolai and Mepraia gajardoi and two chagasic patients from Chile and one from a Bolivian patient with chagasic reactivation. Mixed infections by Tc Ia+Tc Id, Tc Ia+Tc Ie and Tc Id+Tc Ie were detected in vector faeces and isolates from human and vector samples. In addition, Tc Ia and Tc Id were identified in different tissues from a heart transplanted Chagas cardiomyopathy patient with reactivation, denoting histotropism. Trypanosoma cruzi I SL-IR genotypes from parasites infecting Triatoma gerstaeckeri and Didelphis virginiana from USA, T. infestans from Paraguay, Rhodnius nasutus and Rhodnius neglectus from Brazil and M. spinolai and M. gajardoi from Chile are to our knowledge described for the first time. Copyright © 2010 Australian Society for Parasitology
Molecular phylogeny of Triatomini (Hemiptera: Reduviidae: Triatominae)
2014-01-01
Background The Triatomini and Rhodniini (Hemiptera: Reduviidae) tribes include the most diverse Chagas disease vectors; however, the phylogenetic relationships within the tribes remain obscure. This study provides the most comprehensive phylogeny of Triatomini reported to date. Methods The relationships between all of the Triatomini genera and representatives of the three Rhodniini species groups were examined in a novel molecular phylogenetic analysis based on the following six molecular markers: the mitochondrial 16S; Cytochrome Oxidase I and II (COI and COII) and Cytochrome B (Cyt B); and the nuclear 18S and 28S. Results Our results show that the Rhodnius prolixus and R. pictipes groups are more closely related to each other than to the R. pallescens group. For Triatomini, we demonstrate that the large complexes within the paraphyletic Triatoma genus are closely associated with their geographical distribution. Additionally, we observe that the divergence within the spinolai and flavida complex clades are higher than in the other Triatoma complexes. Conclusions We propose that the spinolai and flavida complexes should be ranked under the genera Mepraia and Nesotriatoma. Finally, we conclude that a thorough morphological investigation of the paraphyletic genera Triatoma and Panstrongylus is required to accurately assign queries to natural genera. PMID:24685273
Rojo, Gemma; Sandoval-Rodríguez, Alejandra; López, Angélica; Ortiz, Sylvia; Correa, Juana P; Saavedra, Miguel; Botto-Mahan, Carezza; Cattan, Pedro E; Solari, Aldo
2017-08-07
Chagas disease caused by Trypanosoma cruzi is considered a major public health problem in America. After an acute phase the disease changes to a chronic phase with very low parasitemia. The parasite presents high genetic variability with seven discrete typing units (DTUs): TcI-TcVI and Tc bat. The aim of this work is to evaluate fluctuation of parasitemia and T. cruzi DTUs in naturally infected Octodon degus. After animal capture parasitemia was obtained by qPCR and later the animals were evaluated by three serial xenodiagnoses using two insect vector species, Mepraia spinolai and Triatoma infestans. The parasites amplified over time by insect xenodiagnosis were analyzed by conventional PCR and after that the infective T. cruzi were characterized by means of hybridization tests. The determination of O. degus parasitemia before serial xenodiagnosis by qPCR reveals a great heterogeneity from 1 to 812 parasite equivalents/ml in the blood stream. The T. cruzi DTU composition in 23 analyzed animals by xenodiagnosis oscillated from mixed infections with different DTUs to infections without DTU identification or vice versa, this is equivalent to 50% of the studied animals. Detection of triatomine infection and composition of T. cruzi DTUs was achieved more efficiently 40 days post-infection rather than after 80 or 120 days. Trypanosoma cruzi DTUs composition fluctuates over time in naturally infected O. degus. Three replicates of serial xenodiagnosis confirmed that living parasites have been studied. Our results allow us to confirm that M. spinolai and T. infestans are equally competent to maintain T. cruzi DTUs since similar results of infection were obtained after xenodiagnosis procedure.
Guilfoyle, R.A.; Smith, L.M.
1994-12-27
A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site. 2 figures.
Guilfoyle, Richard A.; Smith, Lloyd M.
1994-01-01
A vector comprising a filamentous phage sequence containing a first copy of filamentous phage gene X and other sequences necessary for the phage to propagate is disclosed. The vector also contains a second copy of filamentous phage gene X downstream from a promoter capable of promoting transcription in a bacterial host. In a preferred form of the present invention, the filamentous phage is M13 and the vector additionally includes a restriction endonuclease site located in such a manner as to substantially inactivate the second gene X when a DNA sequence is inserted into the restriction site.
Arenas, Marco; Campos, Ricardo; Coronado, Ximena; Ortiz, Sylvia
2012-01-01
Abstract Fifty-six Trypanosoma cruzi stocks from Chile and neighboring countries and different hosts, humans, and Triatoma infestans and Mepraia sp., vectors of domiciliary and natural environments were characterized by using three molecular markers. These were cytochrome b (Cyt b) gene sequencing, minicircle DNA blotting, and hybridization with five genotype-specific DNA probes and nuclear analysis of 1f8 and gp72 by polymerase chain reaction–restriction fragment length polymorphism. The results with all three molecular markers are concordant, with minor limitations, grouping T. cruzi stocks into four discrete typing units (DTUs) (TcI, TcII, TcV, and TcVI). TcI and TcII stocks were heterogeneous. TcI and TcII stocks were clustered in two main subgroups determined by Cyt b gene sequencing and minicircle hybridization. However, TcV and TcVI stocks were homogeneous and not differentiated by Cyt b gene sequencing or minicircle DNA hybridization. The discriminatory power and limitations of the molecular markers are discussed, as well as the distribution of the four DTUs in the domiciliary and sylvatic transmission cycles of Chile and the limitations of each marker for molecular epidemiological studies performed with T. cruzi stocks rather than the analysis of direct T. cruzi samples from natural hosts. PMID:22022808
Arenas, Marco; Campos, Ricardo; Coronado, Ximena; Ortiz, Sylvia; Solari, Aldo
2012-03-01
Fifty-six Trypanosoma cruzi stocks from Chile and neighboring countries and different hosts, humans, and Triatoma infestans and Mepraia sp., vectors of domiciliary and natural environments were characterized by using three molecular markers. These were cytochrome b (Cyt b) gene sequencing, minicircle DNA blotting, and hybridization with five genotype-specific DNA probes and nuclear analysis of 1f8 and gp72 by polymerase chain reaction-restriction fragment length polymorphism. The results with all three molecular markers are concordant, with minor limitations, grouping T. cruzi stocks into four discrete typing units (DTUs) (TcI, TcII, TcV, and TcVI). TcI and TcII stocks were heterogeneous. TcI and TcII stocks were clustered in two main subgroups determined by Cyt b gene sequencing and minicircle hybridization. However, TcV and TcVI stocks were homogeneous and not differentiated by Cyt b gene sequencing or minicircle DNA hybridization. The discriminatory power and limitations of the molecular markers are discussed, as well as the distribution of the four DTUs in the domiciliary and sylvatic transmission cycles of Chile and the limitations of each marker for molecular epidemiological studies performed with T. cruzi stocks rather than the analysis of direct T. cruzi samples from natural hosts.
ERIC Educational Resources Information Center
Levine, Robert
2004-01-01
The cross-product is a mathematical operation that is performed between two 3-dimensional vectors. The result is a vector that is orthogonal or perpendicular to both of them. Learning about this for the first time while taking Calculus-III, the class was taught that if AxB = AxC, it does not necessarily follow that B = C. This seemed baffling. The…
NASA Technical Reports Server (NTRS)
Gray, Robert M.
1989-01-01
During the past ten years Vector Quantization (VQ) has developed from a theoretical possibility promised by Shannon's source coding theorems into a powerful and competitive technique for speech and image coding and compression at medium to low bit rates. In this survey, the basic ideas behind the design of vector quantizers are sketched and some comments made on the state-of-the-art and current research efforts.
Dovey, D.
1995-03-22
Previous papers have described a general method for visualizing vector fields that involves drawing many small ``glyphs`` to represent the field. This paper shows how to improve the speed of the algorithm by utilizing hardware support for line drawing and extends the technique from regular to unstructured grids. The new approach can be used to visualize vector fields at arbitrary surfaces within regular and unstructured grids. Applications of the algorithm include interactive visualization of transient electromagnetic fields and visualization of velocity fields in fluid flow problems.
Rotations with Rodrigues' Vector
ERIC Educational Resources Information Center
Pina, E.
2011-01-01
The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…
Rotations with Rodrigues' Vector
ERIC Educational Resources Information Center
Pina, E.
2011-01-01
The rotational dynamics was studied from the point of view of Rodrigues' vector. This vector is defined here by its connection with other forms of parametrization of the rotation matrix. The rotation matrix was expressed in terms of this vector. The angular velocity was computed using the components of Rodrigues' vector as coordinates. It appears…
NASA Astrophysics Data System (ADS)
Chen, Kan; Pang, Cheng-Qun; Liu, Xiang; Matsuki, Takayuki
2015-04-01
Inspired by the abundant experimental observation of axial-vector states, we study whether the observed axial-vector states can be categorized into the conventional axial-vector meson family. In this paper we carry out an analysis based on the mass spectra and two-body Okubo-Zweig-Iizuka-allowed decays. Besides testing the possible axial-vector meson assignments, we also predict abundant information for their decays and the properties of some missing axial-vector mesons, which are valuable for further experimental exploration of the observed and predicted axial-vector mesons.
NASA Technical Reports Server (NTRS)
Patel, Umesh D.; Torre, Edward Della; Day, John H. (Technical Monitor)
2002-01-01
A new vector Preisach model, called the Reduced Vector Preisach model (RVPM), was developed for fast computations. This model, derived from the Simplified Vector Preisach model (SVPM), has individual components that like the SVPM are calculated independently using coupled selection rules for the state vector computation. However, the RVPM does not require the rotational correction. Therefore, it provides a practical alternative for computing the magnetic susceptibility using a differential approach. A vector version, using the framework of the DOK model, is implemented. Simulation results for the reduced vector Preisach model are also presented.
Understanding Singular Vectors
ERIC Educational Resources Information Center
James, David; Botteron, Cynthia
2013-01-01
matrix yields a surprisingly simple, heuristical approximation to its singular vectors. There are correspondingly good approximations to the singular values. Such rules of thumb provide an intuitive interpretation of the singular vectors that helps explain why the SVD is so…
Understanding Singular Vectors
ERIC Educational Resources Information Center
James, David; Botteron, Cynthia
2013-01-01
matrix yields a surprisingly simple, heuristical approximation to its singular vectors. There are correspondingly good approximations to the singular values. Such rules of thumb provide an intuitive interpretation of the singular vectors that helps explain why the SVD is so…
Browning, Diana L.; Collins, Casey P.; Hocum, Jonah D.; Leap, David J.; Rae, Dustin T.; Trobridge, Grant D.
2016-01-01
Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34+ cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy. PMID:26715244
Restart 68000 vector remapping
Gustin, J.
1984-05-03
The circuit described allows power-on-reset (POR) vector fetch from ROM for a 68000 microprocessor. It offers programmability of exception vectors, including the restart vector. This method eliminates the need for high-resolution, address-decoder peripheral circuitry.
ERIC Educational Resources Information Center
Aminu, Abdulhadi
2010-01-01
By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…
ERIC Educational Resources Information Center
Aminu, Abdulhadi
2010-01-01
By rhotrix we understand an object that lies in some way between (n x n)-dimensional matrices and (2n - 1) x (2n - 1)-dimensional matrices. Representation of vectors in rhotrices is different from the representation of vectors in matrices. A number of vector spaces in matrices and their properties are known. On the other hand, little seems to be…
Insulated Foamy Viral Vectors.
Browning, Diana L; Collins, Casey P; Hocum, Jonah D; Leap, David J; Rae, Dustin T; Trobridge, Grant D
2016-03-01
Retroviral vector-mediated gene therapy is promising, but genotoxicity has limited its use in the clinic. Genotoxicity is highly dependent on the retroviral vector used, and foamy viral (FV) vectors appear relatively safe. However, internal promoters may still potentially activate nearby genes. We developed insulated FV vectors, using four previously described insulators: a version of the well-studied chicken hypersensitivity site 4 insulator (650cHS4), two synthetic CCCTC-binding factor (CTCF)-based insulators, and an insulator based on the CCAAT box-binding transcription factor/nuclear factor I (7xCTF/NF1). We directly compared these insulators for enhancer-blocking activity, effect on FV vector titer, and fidelity of transfer to both proviral long terminal repeats. The synthetic CTCF-based insulators had the strongest insulating activity, but reduced titers significantly. The 7xCTF/NF1 insulator did not reduce titers but had weak insulating activity. The 650cHS4-insulated FV vector was identified as the overall most promising vector. Uninsulated and 650cHS4-insulated FV vectors were both significantly less genotoxic than gammaretroviral vectors. Integration sites were evaluated in cord blood CD34(+) cells and the 650cHS4-insulated FV vector had fewer hotspots compared with an uninsulated FV vector. These data suggest that insulated FV vectors are promising for hematopoietic stem cell gene therapy.
Covariantized vector Galileons
NASA Astrophysics Data System (ADS)
Hull, Matthew; Koyama, Kazuya; Tasinato, Gianmassimo
2016-03-01
Vector Galileons are ghost-free systems containing higher derivative interactions of vector fields. They break the vector gauge symmetry, and the dynamics of the longitudinal vector polarizations acquire a Galileon symmetry in an appropriate decoupling limit in Minkowski space. Using an Arnowitt-Deser-Misner approach, we carefully reconsider the coupling with gravity of vector Galileons, with the aim of studying the necessary conditions to avoid the propagation of ghosts. We develop arguments that put on a more solid footing the results previously obtained in the literature. Moreover, working in analogy with the scalar counterpart, we find indications for the existence of a "beyond Horndeski" theory involving vector degrees of freedom that avoids the propagation of ghosts thanks to secondary constraints. In addition, we analyze a Higgs mechanism for generating vector Galileons through spontaneous symmetry breaking, and we present its consistent covariantization.
Disease Vector Ecology Profile: Haiti
1994-09-01
The elderly and children are most susceptible to infection. VECTOR TRANSMISSION: Primary Vectors: Culex nigripalpus , Aedes taeniorhynchus VECTOR...BIONOMICS: Culex nigripalpus breeds in a broad variety of aquatic habitats including lakes, temporary pools, epiphytic plants, brackish water, and...disease. VECTOR TRANSMISSION: Primary Vectors: Culex quinquefasciatus and Cx. nigripalpus ; both species are primary vectors in the U.S., and both
Keasler, J A
2012-03-27
Vectorization is data parallelism (SIMD, SIMT, etc.) - extension of ISA enabling the same instruction to be performed on multiple data items simultaeously. Many/most CPUs support vectorization in some form. Vectorization is difficult to enable, but can yield large efficiency gains. Extra programmer effort is required because: (1) not all algorithms can be vectorized (regular algorithm structure and fine-grain parallelism must be used); (2) most CPUs have data alignment restrictions for load/store operations (obey or risk incorrect code); (3) special directives are often needed to enable vectorization; and (4) vector instructions are architecture-specific. Vectorization is the best way to optimize for power and performance due to reduced clock cycles. When data is organized properly, a vector load instruction (i.e. movaps) can replace 'normal' load instructions (i.e. movsd). Vector operations can potentially have a smaller footprint in the instruction cache when fewer instructions need to be executed. Hybrid index sets insulate users from architecture specific details. We have applied hybrid index sets to achieve optimal vectorization. We can extend this concept to handle other programming models.
Molecular neurosurgery: vectors and vector delivery strategies.
White, Edward
2012-12-01
Molecular neurosurgery involves the use of vector-mediated gene therapy and gene knockdown to manipulate in vivo gene expression for the treatment of neurological diseases. These techniques have the potential to revolutionise the practice of neurosurgery. However, significant challenges remain to be overcome before these techniques enter routine clinical practice. These challenges have been the subject of intensive research in recent years and include the development of strategies to facilitate effective vector delivery to the brain and the development of both viral and non-viral vectors that are capable of efficient cell transduction without excessive toxicity. This review provides an update on the practice of molecular neurosurgery with particular focus on the practical neurosurgical aspects of vector delivery to the brain. In addition, an introduction to the key vectors employed in clinical trials and a brief overview of previous gene therapy clinical trials is provided. Finally, key areas for future research aimed at increasing the likelihood of the successful translation of gene therapy into clinical trials are highlighted.
Viral Vector Production: Adenovirus.
Kim, Julius W; Morshed, Ramin A; Kane, J Robert; Auffinger, Brenda; Qiao, Jian; Lesniak, Maciej S
2016-01-01
Adenoviral vectors have proven to be valuable resources in the development of novel therapies aimed at targeting pathological conditions of the central nervous system, including Alzheimer's disease and neoplastic brain lesions. Not only can some genetically engineered adenoviral vectors achieve remarkably efficient and specific gene delivery to target cells, but they also may act as anticancer agents by selectively replicating within cancer cells.Due to the great interest in using adenoviral vectors for various purposes, the need for a comprehensive protocol for viral vector production is especially apparent. Here, we describe the process of generating an adenoviral vector in its entirety, including the more complex process of adenoviral fiber modification to restrict viral tropism in order to achieve more efficient and specific gene delivery.
Vector generator scan converter
Moore, James M.; Leighton, James F.
1990-01-01
High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O (input/output) channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardward for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold.
Vector generator scan converter
Moore, J.M.; Leighton, J.F.
1988-02-05
High printing speeds for graphics data are achieved with a laser printer by transmitting compressed graphics data from a main processor over an I/O channel to a vector generator scan converter which reconstructs a full graphics image for input to the laser printer through a raster data input port. The vector generator scan converter includes a microprocessor with associated microcode memory containing a microcode instruction set, a working memory for storing compressed data, vector generator hardware for drawing a full graphic image from vector parameters calculated by the microprocessor, image buffer memory for storing the reconstructed graphics image and an output scanner for reading the graphics image data and inputting the data to the printer. The vector generator scan converter eliminates the bottleneck created by the I/O channel for transmitting graphics data from the main processor to the laser printer, and increases printer speed up to thirty fold. 7 figs.
ERIC Educational Resources Information Center
Balabanian, Norman
This programed booklet is designed for the engineering student who understands and can use vector and unit vector notation, components of a vector, parallel law of vector addition, and the dot product of two vectors. Content begins with work done by a force in moving a body a certain distance along some path. For each of the examples and problem…
Possee, Robert D; King, Linda A
2016-01-01
The production of a recombinant baculovirus expression vector normally involves mixing infectious virus DNA with a plasmid-based transfer vector and then co-transfecting insect cells to initiate virus infection. The aim of this chapter is to provide an update on the range of baculovirus transfer vectors currently available. Some of the original transfer vectors developed are now difficult to obtain but generally have been replaced by superior reagents. We focus on those that are available commercially and should be easy to locate. These vectors permit the insertion of single or multiple genes for expression, or the production of proteins with specific peptide tags that aid subsequent protein purification. Others have signal peptide coding regions permitting protein secretion or plasma membrane localization. A table listing the transfer vectors also includes information on the parental virus that should be used with each one. Methods are described for the direct insertion of a recombinant gene into the virus genome without the requirement for a transfer vector. The information provided should enable new users of the system to choose those reagents most suitable for their purposes.
Autonomous parvovirus vectors.
Maxwell, Ian H; Terrell, Kristina L; Maxwell, Françoise
2002-10-01
Parvoviruses are small, icosahedral viruses (approximately 25 nm) containing a single-strand DNA genome (approximately 5 kb) with hairpin termini. Autonomous parvoviruses (APVs) are found in many species; they do not require a helper virus for replication but they do require proliferating cells (S-phase functions) and, in some cases, tissue-specific factors. APVs can protect animals from spontaneous or experimental tumors, leading to consideration of these viruses, and vectors derived from them, as anticancer agents. Vector development has focused on three rodent APVs that can infect human cells, namely, LuIII, MVM, and H1. LuIII-based vectors with complete replacement of the viral coding sequences can direct transient or persistent expression of transgenes in cell culture. MVM-based and H1-based vectors with substitution of transgenes for the viral capsid sequences retain viral nonstructural (NS) coding sequences and express the NS1 protein. The latter serves to amplify the vector genome in target cells, potentially contributing to antitumor activity. APV vectors have packaging capacity for foreign DNA of approximately 4.8 kb, a limit that probably cannot be exceeded by more than a few percent. LuIII vectors can be pseudotyped with capsid proteins from related APVs, a promising strategy for controlling tissue tropism and circumventing immune responses to repeated administration. Initial success has been achieved in targeting such a pseudotyped vector by genetic modification of the capsid. Subject to advances in production and purification methods, APV vectors have potential as gene transfer agents for experimental and therapeutic use, particularly for cancer therapy. Copyright 2002 Elsevier Science (USA)
NASA Astrophysics Data System (ADS)
Lukács, B.; Perjés, Z.; Sebestyén, Á.
1981-06-01
Space-times admitting a null Killing vector are studied, using the Newman-Penrose spin coefficient formalism. The properties of the eigenrays (principal null curves of the Killing bivector) are shown to be related to the twist of the null Killing vector. Among the electrovacs, the ones containing a null Maxwell field turn out to belong to the twist-free class. An electrovac solution is obtained for which the null Killing vector is twisting and has geodesic and shear-free eigenrays. This solution is parameterless and appears to be the field of a zero-mass, spinning, and charged source.
The Vector Decomposition Problem
NASA Astrophysics Data System (ADS)
Yoshida, Maki; Mitsunari, Shigeo; Fujiwara, Toru
This paper introduces a new computational problem on a two-dimensional vector space, called the vector decomposition problem (VDP), which is mainly defined for designing cryptosystems using pairings on elliptic curves. We first show a relation between the VDP and the computational Diffie-Hellman problem (CDH). Specifically, we present a sufficient condition for the VDP on a two-dimensional vector space to be at least as hard as the CDH on a one-dimensional subspace. We also present a sufficient condition for the VDP with a fixed basis to have a trapdoor. We then give an example of vector spaces which satisfy both sufficient conditions and on which the CDH is assumed to be hard in previous work. In this sense, the intractability of the VDP is a reasonable assumption as that of the CDH.
NASA Astrophysics Data System (ADS)
Douglas, Joanne T.
The practical implementation of gene therapy in the clinical setting mandates gene delivery vehicles, or vectors, capable of efficient gene delivery selectively to the target disease cells. The utility of adenoviral vectors for gene therapy is restricted by their dependence on the native adenoviral primary cellular receptor for cell entry. Therefore, a number of strategies have been developed to allow CAR-independent infection of specific cell types, including the use of bispecific conjugates and genetic modifications to the adenoviral capsid proteins, in particular the fibre protein. These targeted adenoviral vectors have demonstrated efficient gene transfer in vitro , correlating with a therapeutic benefit in preclinical animal models. Such vectors are predicted to possess enhanced efficacy in human clinical studies, although anatomical barriers to their use must be circumvented.
Lewis, C.M. )
1991-09-15
A vector field {ital A}{sub {mu}} is coupled to the Einstein equations with a linearly perturbed Friedmann-Robertson-Walker metric, constructed to generate first-order vector perturbations. A working classical chaotic vector inflation is demonstrated and then quantum fluctuations of the field are used to constrain the cosmological perturbations. In particular, the vector momentum flux {ital T}{sub 0{ital i}} is tracked to the epoch where radiation-dominated matter exists. Matching conditions using observational constraints of the cosmic microwave background radiation give rise to a peculiar cosmological velocity of the order of 10{sup {minus}100}{ital c}. Amplification of this number, e.g., by breaking the conformal invariance of the field, could be used to generate cosmic magnetic fields using a dynamo mechanism.
Saccharomyces cerevisiae Shuttle vectors.
Gnügge, Robert; Rudolf, Fabian
2017-01-10
Yeast shuttle vectors are indispensable tools in yeast research. They enable cloning of defined DNA sequences in Escherichia coli and their direct transfer into Saccharomyces cerevisiae cells. There are three types of commonly used yeast shuttle vectors: centromeric plasmids, episomal plasmids and integrating plasmids. In this review, we discuss the different plasmid systems and their characteristic features. We focus on their segregational stability and copy number and indicate how to modify these properties. Copyright © 2017 John Wiley & Sons, Ltd.
Carrigan, Charles R [Tracy, CA
2011-08-02
A determination is made of frequency components associated with a particular bearing or location resulting from sources emitting electromagnetic-wave energy for which a Poynting-Vector can be defined. The broadband frequency components associated with a specific direction or location of interest are isolated from other components in the power spectrum that are not associated with the direction or location of interest. The collection of pointing vectors can be used to characterize the source.
NASA Technical Reports Server (NTRS)
Wang, Li-Jun; Bacon, A. M.; Zhao, H.-Z.; Thomas, J. E.
1994-01-01
In the optical measurement of the Bloch vector components describing a system of N two-level atoms, the quantum fluctuations in these components are coupled into the measuring optical field. This paper develops the quantum theory of optical measurement of Bloch vector projection noise. The preparation and probing of coherence in an effective two-level system consisting of the two ground states in an atomic three-level lambda-scheme are analyzed.
Syngeneic AAV pseudo-vectors potentiates full vector transduction
USDA-ARS?s Scientific Manuscript database
An excessive amount of empty capsids are generated during regular AAV vector production process. These pseudo-vectors often remain in final vectors used for animal studies or clinical trials. The potential effects of these pseudo-vectors on AAV transduction have been a major concern. In the current ...
Vector and Axial Vector Pion Form Factors
NASA Astrophysics Data System (ADS)
Vitz, Michael; PEN Collaboration
2015-04-01
Radiative pion decay π+ -->e+ νγ (RPD) provides critical input to chiral perturbation theory (χPT). Aside from the uninteresting ``inner bremsstrahlung'' contribution from QED, the RPD rate contains ``structure dependent'' terms given by FV and FA, the vector and axial-vector pion form factors, respectively. The two appear in the decay rate in combinations FV -FA and FV +FA , i.e., in the so-called SD- and SD+ terms, respectively. The latter has been measured to high precision by the PIBETA collaboration. We report on the analysis of new data, measured by the PEN collaboration in runs between 2008 and 2010 at the Paul Scherrer Institute, Switzerland. We particularly focus on the possibility of improvement in the determination of the SD- term. Precise determinations of FV and FA test the validity of the CVC hypothesis, provide numerical input for the l9 +l10 terms in the χPT lagrangian, and constrain potential non-(V - A) terms, such as a possible tensor term FT. NSF grants PHY-0970013, 1307328, and others.
Bunyavirus-vector interactions.
Beaty, B J; Bishop, D H
1988-06-01
Recent advances in the genetics and molecular biology of bunyaviruses have been applied to understanding bunyavirus-vector interactions. Such approaches have revealed which virus gene and gene products are important in establishing infections in vectors and in transmission of viruses. However, much more information is required to understand the molecular mechanisms of persistent infections of vectors which are lifelong but apparently exert no untoward effect. In fact, it seems remarkable that LAC viral antigen can be detected in almost every cell in an ovarian follicle, yet no untoward effect on fecundity and no teratology is seen. Similarly the lifelong infection of the vector would seem to provide ample opportunity for bunyavirus evolution by genetic drift and, under the appropriate circumstances, by segment reassortment. The potential for bunyavirus evolution by segment reassortment in vectors certainly exists. For example the Group C viruses in a small forest in Brazil seem to constitute a gene pool, with the 6 viruses related alternately by HI/NT and CF reactions, which assay respectively M RNA and S RNA gene products (Casals and Whitman, 1960; Shope and Causey, 1962). Direct evidence for naturally occurring reassortant bunyaviruses has also been obtained. Oligonucleotide fingerprint analyses of field isolates of LAC virus and members of the Patois serogroup of bunyaviruses have demonstrated that reassortment does occur in nature (El Said et al., 1979; Klimas et al., 1981; Ushijima et al., 1981). Determination of the genotypic frequencies of viruses selected by the biological interactions of viruses and vectors after dual infection and segment reassortment is an important issue. Should a virus result that efficiently interacts with alternate vector species, the virus could be expressed in different circumstances with serious epidemiologic consequences. Dual infection of vectors with different viruses is not unlikely, because many bunyaviruses are sympatric in
NASA Astrophysics Data System (ADS)
Barbarien, Joeri; Munteanu, Adrian; Verdicchio, Fabio; Andreopoulos, Yiannis; Cornelis, Jan P.; Schelkens, Peter
2004-11-01
Modern video coding applications require transmission of video data over variable-bandwidth channels to a variety of terminals with different screen resolutions and available computational power. Scalable video coding is needed to optimally support these applications. Recently proposed wavelet-based video codecs employing spatial domain motion compensated temporal filtering (SDMCTF) provide quality, resolution and frame-rate scalability while delivering compression performance comparable to that of the state-of-the-art non-scalable H.264-codec. These codecs require scalable coding of the motion vectors in order to support a large range of bit-rates with optimal compression efficiency. Scalable motion vector coding algorithms based on the integer wavelet transform followed by embedded coding of the wavelet coefficients were recently proposed. In this paper, a new and fundamentally different scalable motion vector codec (MVC) using median-based motion vector prediction is proposed. Extensive experimental results demonstrate that the proposed MVC systematically outperforms the wavelet-based state-of-the-art solutions. To be able to take advantage of the proposed scalable MVC, a rate allocation mechanism capable of optimally dividing the available rate among texture and motion information is required. Two rate allocation strategies are proposed and compared. The proposed MVC and rate allocation schemes are incorporated into an SDMCTF-based video codec and the benefits of scalable motion vector coding are experimentally demonstrated.
NASA Astrophysics Data System (ADS)
Yan, Zhenya
2011-11-01
The coupled nonlinear volatility and option pricing model presented recently by Ivancevic is investigated, which generates a leverage effect, i.e., stock volatility is (negatively) correlated to stock returns, and can be regarded as a coupled nonlinear wave alternative of the Black-Scholes option pricing model. In this Letter, we analytically propose vector financial rogue waves of the coupled nonlinear volatility and option pricing model without an embedded w-learning. Moreover, we exhibit their dynamical behaviors for chosen different parameters. The vector financial rogue wave (rogon) solutions may be used to describe the possible physical mechanisms for the rogue wave phenomena and to further excite the possibility of relative researches and potential applications of vector rogue waves in the financial markets and other related fields.
NASA Astrophysics Data System (ADS)
Rejon-Barrera, Fernando; Robbins, Daniel
2016-01-01
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
Bunyavirus-Vector Interactions
Horne, Kate McElroy; Vanlandingham, Dana L.
2014-01-01
The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family. PMID:25402172
NASA Technical Reports Server (NTRS)
Garay, Michael J.; Mazzoni, Dominic; Davies, Roger; Wagstaff, Kiri
2004-01-01
Support Vector Machines (SVMs) are a type of supervised learning algorith,, other examples of which are Artificial Neural Networks (ANNs), Decision Trees, and Naive Bayesian Classifiers. Supervised learning algorithms are used to classify objects labled by a 'supervisor' - typically a human 'expert.'.
ERIC Educational Resources Information Center
Dean, Richard A.
1971-01-01
The author shows that the set of all sequences in which each term is the sum of the two previous terms forms a vector space of dimension two. He uses this result to obtain the formula for the Fibonacci sequence and applies the same technique to other linear recursive relations. (MM)
Killing vectors and anisotropy
Krisch, J. P.; Glass, E. N.
2009-08-15
We consider an action that can generate fluids with three unequal stresses for metrics with a spacelike Killing vector. The parameters in the action are directly related to the stress anisotropies. The field equations following from the action are applied to an anisotropic cosmological expansion and an extension of the Gott-Hiscock cosmic string.
Production of lentiviral vectors
Merten, Otto-Wilhelm; Hebben, Matthias; Bovolenta, Chiara
2016-01-01
Lentiviral vectors (LV) have seen considerably increase in use as gene therapy vectors for the treatment of acquired and inherited diseases. This review presents the state of the art of the production of these vectors with particular emphasis on their large-scale production for clinical purposes. In contrast to oncoretroviral vectors, which are produced using stable producer cell lines, clinical-grade LV are in most of the cases produced by transient transfection of 293 or 293T cells grown in cell factories. However, more recent developments, also, tend to use hollow fiber reactor, suspension culture processes, and the implementation of stable producer cell lines. As is customary for the biotech industry, rather sophisticated downstream processing protocols have been established to remove any undesirable process-derived contaminant, such as plasmid or host cell DNA or host cell proteins. This review compares published large-scale production and purification processes of LV and presents their process performances. Furthermore, developments in the domain of stable cell lines and their way to the use of production vehicles of clinical material will be presented. PMID:27110581
Citrin, D S
2012-06-15
A linearly polarized Bessel beam, whose spatial frequencies correspond to the Brewster angle, impinging at normal incidence on a higher refractive-index interface is shown to lead to a reflected field that can be used to produce an azimuthally polarized optical vector beam.
Vande Woude, G.F.; McClements, W.L.; Oskarsson, M.K.; Blair, D.G.
1981-07-01
The patent application describes the production of vectors composed of portions of retrovirus, particularly of Moloney sarcoma virus DNA including the 'LTR' sequence which can activate genes and additional viral sequences which can 'rescue' these genes into a replicating virus particle.
NASA Technical Reports Server (NTRS)
Garay, Michael J.; Mazzoni, Dominic; Davies, Roger; Wagstaff, Kiri
2004-01-01
Support Vector Machines (SVMs) are a type of supervised learning algorith,, other examples of which are Artificial Neural Networks (ANNs), Decision Trees, and Naive Bayesian Classifiers. Supervised learning algorithms are used to classify objects labled by a 'supervisor' - typically a human 'expert.'.
Tolmachov, Oleg
2009-01-01
Nonviral gene therapy vectors are commonly based on recombinant bacterial plasmids or their derivatives. The plasmids are propagated in bacteria, so, in addition to their therapeutic cargo, they necessarily contain a bacterial replication origin and a selection marker, usually a gene conferring antibiotic resistance. Structural and maintenance plasmid stability in bacteria is required for the plasmid DNA production and can be achieved by carefully choosing a combination of the therapeutic DNA sequences, replication origin, selection marker, and bacterial strain. The use of appropriate promoters, other regulatory elements, and mammalian maintenance devices ensures that the therapeutic gene or genes are adequately expressed in target human cells. Optimal immune response to the plasmid vectors can be modulated via inclusion or exclusion of DNA sequences containing immunostimulatory CpG sequence motifs. DNA fragments facilitating construction of plasmid vectors should also be considered for inclusion in the design of plasmid vectors. Techniques relying on site-specific or homologous recombination are preferred for construction of large plasmids (>15 kb), while digestion of DNA by restriction enzymes with subsequent ligation of the resulting DNA fragments continues to be the mainstream approach for generation of small- and medium-size plasmids. Rapid selection of a desired recombinant plasmid against a background of other plasmids continues to be a challenge. In this chapter, the emphasis is placed on efficient and flexible versions of DNA cloning protocols using selection of recombinant plasmids by restriction endonucleases directly in the ligation mixture.
Singular Vectors' Subtle Secrets
ERIC Educational Resources Information Center
James, David; Lachance, Michael; Remski, Joan
2011-01-01
Social scientists use adjacency tables to discover influence networks within and among groups. Building on work by Moler and Morrison, we use ordered pairs from the components of the first and second singular vectors of adjacency matrices as tools to distinguish these groups and to identify particularly strong or weak individuals.
Wilson, Anthony James; Morgan, Eric René; Booth, Mark; Norman, Rachel; Perkins, Sarah Elizabeth; Hauffe, Heidi Christine; Mideo, Nicole; Antonovics, Janis; McCallum, Hamish; Fenton, Andy
2017-05-05
Many important and rapidly emerging pathogens of humans, livestock and wildlife are 'vector-borne'. However, the term 'vector' has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the 'haematophagous arthropod' and 'mobility' definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the 'micropredator' and 'sequential' definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study.This article is part of the themed issue 'Opening the black box: re-examining the ecology and evolution of parasite transmission'. © 2017 The Authors.
Gubler, D J
2009-08-01
Vector-borne diseases have been the scourge of man and animals since the beginning of time. Historically, these are the diseases that caused the great plagues such as the 'Black Death' in Europe in the 14th Century and the epidemics of yellow fever that plagued the development of the New World. Others, such as Nagana, contributed to the lack of development in Africa for many years. At the turn of the 20th Century, vector-borne diseases were among the most serious public and animal health problems in the world. For the most part, these diseases were controlled by the middle of the 20th Century through the application of knowledge about their natural history along with the judicious use of DDT (dichlorodiphenyltrichloroethane) and other residual insecticides to interrupt the transmission cycle between arthropod and vertebrate host. However, this success initiated a period of complacency in the 1960s and 1970s, which resulted in the redirection of resources away from prevention and control of vector-borne diseases. The 1970s was also a time in which there were major changes to public health policy. Global trends, combined with changes in animal husbandry, urbanisation, modern transportation and globalisation, have resulted in a global re-emergence of epidemic vector-borne diseases affecting both humans and animals over the past 30 years.
Singular Vectors' Subtle Secrets
ERIC Educational Resources Information Center
James, David; Lachance, Michael; Remski, Joan
2011-01-01
Social scientists use adjacency tables to discover influence networks within and among groups. Building on work by Moler and Morrison, we use ordered pairs from the components of the first and second singular vectors of adjacency matrices as tools to distinguish these groups and to identify particularly strong or weak individuals.
NASA Technical Reports Server (NTRS)
Hafez, M.
1989-01-01
Vector potential and related methods, for the simulation of both inviscid and viscous flows over aerodynamic configurations, are briefly reviewed. The advantages and disadvantages of several formulations are discussed and alternate strategies are recommended. Scalar potential, modified potential, alternate formulations of Euler equations, least-squares formulation, variational principles, iterative techniques and related methods, and viscous flow simulation are discussed.
NASA Astrophysics Data System (ADS)
Davydov, E. A.
2012-06-01
Vector fields can arise in the cosmological context in different ways, and we discuss both abelian and nonabelian sector. In the abelian sector vector fields of the geometrical origin (from dimensional reduction and Einstein-Eddington modification of gravity) can provide a very non-trivial dynamics, which can be expressed in terms of the effective dilaton-scalar gravity with the specific potential. In the non-abelian sector we investigate the Yang-Mills SU(2) theory which admits isotropic and homogeneous configuration. Provided the non-linear dependence of the lagrangian on the invariant FμνF~μν, one can obtain the inflationary regime with the exponential growth of the scale factor. The effective amplitudes of the `electric' and `magnetic' components behave like slowly varying scalars at this regime, what allows the consideration of some realistic models with non-linear terms in the Yang-Mills lagrangian.
2015-09-28
300001 1 of 16 VEHICLE-BASED VECTOR SENSOR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0002] None. BACKGROUND OF THE INVENTION (1) Field of the Invention [0003] The invention is an... invention , is a small volume of fluid surrounding a point where averaged properties (e.g., velocity, temperature, etc.) can be analyzed with continuum
NASA Technical Reports Server (NTRS)
Chipman, Russell A.
1996-01-01
This report covers work performed during the period of November 1994 through March 1996 on the design of a Space-borne Solar Vector Magnetograph. This work has been performed as part of a design team under the supervision of Dr. Mona Hagyard and Dr. Alan Gary of the Space Science Laboratory. Many tasks were performed and this report documents the results from some of those tasks, each contained in the corresponding appendix. Appendices are organized in chronological order.
Some experiences with Krylov vectors and Lanczos vectors
NASA Technical Reports Server (NTRS)
Craig, Roy R., Jr.; Su, Tzu-Jeng; Kim, Hyoung M.
1993-01-01
This paper illustrates the use of Krylov vectors and Lanczos vectors for reduced-order modeling in structural dynamics and for control of flexible structures. Krylov vectors and Lanczos vectors are defined and illustrated, and several applications that have been under study at The University of Texas at Austin are reviewed: model reduction for undamped structural dynamics systems, component mode synthesis using Krylov vectors, model reduction of damped structural dynamics systems, and one-sided and two-sided unsymmetric block-Lanczos model-reduction algorithms.
Isomap based supporting vector machine
NASA Astrophysics Data System (ADS)
Liang, W. N.
2015-12-01
This research presents a new isomap based supporting vector machine method. Isomap is a dimension reduction method which is able to analyze nonlinear relationship of data on manifolds. Accordingly, support vector machine is established on the isomap manifold to classify given and predict unknown data. A case study of the isomap based supporting vector machine for environmental planning problems is conducted.
Garcia-Ripoll; Perez-Garcia; Ostrovskaya; Kivshar
2000-07-03
We find a new type of optical vector soliton that originates from trapping of a dipole mode by the soliton-induced waveguides. These solitons, which appear as a consequence of the vector nature of the two-component system, are more stable than the previously found optical vortex solitons and represent a new type of extremely robust nonlinear vector structure.
Morgan, Eric René; Booth, Mark; Norman, Rachel; Mideo, Nicole; McCallum, Hamish; Fenton, Andy
2017-01-01
Many important and rapidly emerging pathogens of humans, livestock and wildlife are ‘vector-borne’. However, the term ‘vector’ has been applied to diverse agents in a broad range of epidemiological systems. In this perspective, we briefly review some common definitions, identify the strengths and weaknesses of each and consider the functional differences between vectors and other hosts from a range of ecological, evolutionary and public health perspectives. We then consider how the use of designations can afford insights into our understanding of epidemiological and evolutionary processes that are not otherwise apparent. We conclude that from a medical and veterinary perspective, a combination of the ‘haematophagous arthropod’ and ‘mobility’ definitions is most useful because it offers important insights into contact structure and control and emphasizes the opportunities for pathogen shifts among taxonomically similar species with similar feeding modes and internal environments. From a population dynamics and evolutionary perspective, we suggest that a combination of the ‘micropredator’ and ‘sequential’ definition is most appropriate because it captures the key aspects of transmission biology and fitness consequences for the pathogen and vector itself. However, we explicitly recognize that the value of a definition always depends on the research question under study. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289253
Vector Helmholtz-Gauss and vector Laplace-Gauss beams.
Bandres, Miguel A; Gutiérrez-Vega, Julio C
2005-08-15
We demonstrate the existence of vector Helmholtz-Gauss (vHzG) and vector Laplace-Gauss beams that constitute two general families of localized vector beam solutions of the Maxwell equations in the paraxial approximation. The electromagnetic components are determined starting from the scalar solutions of the two-dimensional Helmholtz and Laplace equations, respectively. Special cases of the vHzG beams are TE and TM Gaussian vector beams, nondiffracting vector Bessel beams, polarized Bessel-Gauss beams, modes in cylindrical waveguides and cavities, and scalar Helmholtz-Gauss beams. The general expression of the vHzG beams can be used straightforwardly to obtain vector Mathieu-Gauss and vector parabolic-Gauss beams, which to our knowledge have not yet been reported.
Vector representation of tourmaline compositions
NASA Technical Reports Server (NTRS)
Burt, Donald M.
1989-01-01
The vector method for representing mineral compositions of amphibole and mica groups is applied to the tourmaline group. Consideration is given to the methods for drawing the relevant vector diagrams, relating the exchange vectors to one another, and contouring the diagrams for constant values of Na, Ca, Li, Fe, Mg, Al, Si, and OH. The method is used to depict a wide range of possible tourmaline end-member compositions and solid solutions, starting from a single point. In addition to vector depictions of multicomponent natural tourmalines, vectors are presented for simpler systems such as (Na,Al)-tourmalines, alkali-free tourmalines, and elbaites.
Vector ecology of equine piroplasmosis.
Scoles, Glen A; Ueti, Massaro W
2015-01-07
Equine piroplasmosis is a disease of Equidae, including horses, donkeys, mules, and zebras, caused by either of two protozoan parasites, Theileria equi or Babesia caballi. These parasites are biologically transmitted between hosts via tick vectors, and although they have inherent differences they are categorized together because they cause similar pathology and have similar morphologies, life cycles, and vector relationships. To complete their life cycle, these parasites must undergo a complex series of developmental events, including sexual-stage development in their tick vectors. Consequently, ticks are the definitive hosts as well as vectors for these parasites, and the vector relationship is restricted to a few competent tick species. Because the vector relationship is critical to the epidemiology of these parasites, we highlight current knowledge of the vector ecology of these tick-borne equine pathogens, emphasizing tick transmissibility and potential control strategies to prevent their spread.
Aerodynamics of thrust vectoring
NASA Technical Reports Server (NTRS)
Tseng, J. B.; Lan, C. Edward
1989-01-01
Thrust vectoring as a means to enhance maneuverability and aerodynamic performane of a tactical aircraft is discussed. This concept usually involves the installation of a multifunction nozzle. With the nozzle, the engine thrust can be changed in direction without changing the attitude of the aircraft. Change in the direction of thrust induces a significant change in the aerodynamic forces on the aircraft. Therefore, this device can be used for lift-augmenting as well as stability and control purposes. When the thrust is deflected in the longitudinal direction, the lift force and the pitching stability can be manipulated, while the yawing stability can be controlled by directing the thrust in the lateral direction.
NASA Technical Reports Server (NTRS)
King, H. J.; Schnelker, D.; Ward, J. W.; Dulgeroff, C.; Vahrenkamp, R.
1972-01-01
The design, fabrication, and testing of thrust vectorable ion optical systems capable of controlling the thrust direction from both 5- and 30-cm diameter ion thrusters is described. Both systems are capable of greater than 10 deg thrust deflection in any azimuthal direction. The 5-cm system is electrostatic and hence has a short response time and minimal power consumption. It has recently been tested for more than 7500 hours on an operational thruster. The 30-cm system is mechanical, has a response time of the order of 1 min, and consumes less than 0.3% of the total system input power at full deflection angle.
Vector potential photoelectron microscopy.
Browning, R
2011-10-01
A new class of electron microscope has been developed for the chemical microanalysis of a wide range of real world samples using photoelectron spectroscopy. Highly structured, three-dimensional samples, such as fiber mats and fracture surfaces can be imaged, as well as insulators and magnetic materials. The new microscope uses the vector potential field from a solenoid magnet as a spatial reference for imaging. A prototype instrument has demonstrated imaging of uncoated silk, magnetic steel wool, and micron-sized single strand tungsten wires.
Extended vector-tensor theories
NASA Astrophysics Data System (ADS)
Kimura, Rampei; Naruko, Atsushi; Yoshida, Daisuke
2017-01-01
Recently, several extensions of massive vector theory in curved space-time have been proposed in many literatures. In this paper, we consider the most general vector-tensor theories that contain up to two derivatives with respect to metric and vector field. By imposing a degeneracy condition of the Lagrangian in the context of ADM decomposition of space-time to eliminate an unwanted mode, we construct a new class of massive vector theories where five degrees of freedom can propagate, corresponding to three for massive vector modes and two for massless tensor modes. We find that the generalized Proca and the beyond generalized Proca theories up to the quartic Lagrangian, which should be included in this formulation, are degenerate theories even in curved space-time. Finally, introducing new metric and vector field transformations, we investigate the properties of thus obtained theories under such transformations.
Hyperbolic-symmetry vector fields.
Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian
2015-12-14
We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.
An adaptive vector quantization scheme
NASA Technical Reports Server (NTRS)
Cheung, K.-M.
1990-01-01
Vector quantization is known to be an effective compression scheme to achieve a low bit rate so as to minimize communication channel bandwidth and also to reduce digital memory storage while maintaining the necessary fidelity of the data. However, the large number of computations required in vector quantizers has been a handicap in using vector quantization for low-rate source coding. An adaptive vector quantization algorithm is introduced that is inherently suitable for simple hardware implementation because it has a simple architecture. It allows fast encoding and decoding because it requires only addition and subtraction operations.
Safety considerations in vector development.
Kappes, J C; Wu, X
2001-11-01
The inadvertent production of replication competent retrovirus (RCR) constitutes the principal safety concern for the use of lentiviral vectors in human clinical protocols. Because of limitations in animal models to evaluate lentiviral vectors for their potential to recombine and induce disease, the vector design itself should ensure against the emergence of RCR in vivo. Issues related to RCR generation and one approach to dealing with this problem are discussed in this chapter. To assess the risk of generating RCR, a highly sensitive biological assay was developed to specifically detect vector recombination in transduced cells. Analysis of lentiviral vector stocks has shown that recombination occurs during reverse transcription in primary target cells. Rejoining of viral protein-coding sequences of the packaging construct and cis-acting sequences of the vector was demonstrated to generate env-minus recombinants (LTR-gag-pol-LTR). Mobilization of recombinant lentiviral genomes was also demonstrated but was dependent on pseudotyping of the vector core with an exogenous envelope protein. 5' sequence analysis has demonstrated that recombinants consist of U3, R, U5, and the psi packaging signal joined with an open gag coding region. Analysis of the 3' end has mapped the point of vector recombination to the poly(A) tract of the packaging construct's mRNA. The state-of-the-art third generation packaging construct and SIN vector also have been shown to generate env-minus proviral recombinants capable of mobilizing retroviral DNA when pseudotyped with an exogenous envelope protein. A new class of HIV-based vector (trans-vector) was recently developed that splits the gag-pol component of the packaging construct into two parts: one that expresses Gag/Gag-Pro and another that expresses Pol (RT and IN) fused with Vpr. Unlike other lentiviral vectors, the trans-vector has not been shown to form recombinants capable of DNA mobilization. These results indicate the trans-vector
Multistage vector (MSV) therapeutics.
Wolfram, Joy; Shen, Haifa; Ferrari, Mauro
2015-12-10
One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers. Copyright © 2015 Elsevier B.V. All rights reserved.
NASA Technical Reports Server (NTRS)
Hagyard, M. J.; Cumings, N. P.; West, E. A.
1981-01-01
The NASA/Marshall Space Flight Center's solar vector magnetograph system allows measurements of all components of the Sun's photospheric magnetic field over a 5 x 5 or 2.5 x 2.5 arc min square field of view with an optimum time resolution of approximately 100 sec and an optimum signal-to-noise of approximately 1000. The basic system components are described, including the optics, detector, digital system, and associated electronics. Automatic sequencing and control functions are outlined as well as manual selections of system parameters which afford unique system flexibility. Results of system calibration and performance are presented, including linearity, dynamic range, uniformity, spatial and spectral resolutions, signal-to-noise, electro-optical retardation and polarization calibration.
Nelson, Ann E.
2008-05-01
We show that for a force mediated by a vector particle coupled to a conserved U(1) charge, the apparent range and strength can depend on the size and density of the source, and the proximity to other sources. This chameleon effect is due to screening from a light charged scalar. Such screening can weaken astrophysical constraints on new gauge bosons. As an example we consider the constraints on chameleonic gauged B-L. We show that although Casimir measurements greatly constrain any B-L force much stronger than gravity with range longer than 0.1 {mu}m, there remains an experimental window for a long-range chameleonic B-L force. Such a force could be much stronger than gravity, and long or infinite range in vacuum, but have an effective range near the surface of the earth which is less than a micron.
NASA Astrophysics Data System (ADS)
D'Ambrosio, Vincenzo; Carvacho, Gonzalo; Graffitti, Francesco; Vitelli, Chiara; Piccirillo, Bruno; Marrucci, Lorenzo; Sciarrino, Fabio
2016-09-01
Light beams having a vectorial field structure, or polarization, that varies over the transverse profile and a central optical singularity are called vector vortex (VV) beams and may exhibit specific properties such as focusing into "light needles" or rotation invariance. VV beams have already found applications in areas ranging from microscopy to metrology, optical trapping, nano-optics, and quantum communication. Individual photons in such beams exhibit a form of single-particle quantum entanglement between different degrees of freedom. On the other hand, the quantum states of two photons can be also entangled with each other. Here, we combine these two concepts and demonstrate the generation of quantum entanglement between two photons that are both in VV states: a form of entanglement between two complex vectorial fields. This result may lead to quantum-enhanced applications of VV beams as well as to quantum information protocols fully exploiting the vectorial features of light.
Multistage vector (MSV) therapeutics
Wolfram, Joy; Shen, Haifa; Ferrari, Mauro
2015-01-01
One of the greatest challenges in the field of medicine is obtaining controlled distribution of systemically administered therapeutic agents within the body. Indeed, biological barriers such as physical compartmentalization, pressure gradients, and excretion pathways adversely affect localized delivery of drugs to pathological tissue. The diverse nature of these barriers requires the use of multifunctional drug delivery vehicles that can overcome a wide range of sequential obstacles. In this review, we explore the role of multifunctionality in nanomedicine by primarily focusing on multistage vectors (MSVs). The MSV is an example of a promising therapeutic platform that incorporates several components, including a microparticle, nanoparticles, and small molecules. In particular, these components are activated in a sequential manner in order to successively address transport barriers. PMID:26264836
Solar imaging vector magnetograph
NASA Technical Reports Server (NTRS)
Canfield, Richard C.
1993-01-01
This report describes an instrument which has been constructed at the University of Hawaii to make observations of the magnetic field in solar active regions. Detailed knowledge of active region magnetic structures is crucial to understanding many solar phenomena, because the magnetic field both defines the morphology of structures seen in the solar atmosphere and is the apparent energy source for solar flares. The new vector magnetograph was conceived in response to a perceived discrepancy between the capabilities of X ray imaging telescopes to be operating during the current solar maximum and those of existing magnetographs. There were no space-based magnetographs planned for this period; the existing ground-based instruments variously suffered from lack of sensitivity, poor time resolution, inadequate spatial resolution or unreliable sites. Yet the studies of flares and their relationship to the solar corona planned for the 1991-1994 maximum absolutely required high quality vector magnetic field measurements. By 'vector' measurements we mean that the observation attempts to deduce the complete strength and direction of the field at the measurement site, rather than just the line of sight component as obtained by a traditional longitudinal magnetograph. Knowledge of the vector field permits one to calculate photospheric electric currents, which might play a part in heating the corona, and to calculate energy stored in coronal magnetic fields as the result of such currents. Information about the strength and direction of magnetic fields in the solar atmosphere can be obtained in a number of ways, but quantitative data is best obtained by observing Zeeman-effect polarization in solar spectral lines. The technique requires measuring the complete state of polarization at one or more wavelengths within a magnetically sensitive line of the solar spectrum. This measurement must be done for each independent spatial point for which one wants magnetic field data. All the
Poynting vector and wave vector directions of equatorial chorus
NASA Astrophysics Data System (ADS)
Taubenschuss, Ulrich; Santolík, Ondřej; Breuillard, Hugo; Li, Wen; Le Contel, Olivier
2016-12-01
We present new results on wave vectors and Poynting vectors of chorus rising and falling tones on the basis of 6 years of THEMIS (Time History of Events and Macroscale Interactions during Substorms) observations. The majority of wave vectors is closely aligned with the direction of the ambient magnetic field (B0). Oblique wave vectors are confined to the magnetic meridional plane, pointing away from Earth. Poynting vectors are found to be almost parallel to B0. We show, for the first time, that slightly oblique Poynting vectors are directed away from Earth for rising tones and toward Earth for falling tones. For the majority of lower band chorus elements, the mutual orientation between Poynting vectors and wave vectors can be explained by whistler mode dispersion in a homogeneous collisionless cold plasma. Upper band chorus seems to require inclusion of collisional processes or taking into account azimuthal anisotropies in the propagation medium. The latitudinal extension of the equatorial source region can be limited to ±6∘ around the B0 minimum or approximately ±5000 km along magnetic field lines. We find increasing Poynting flux and focusing of Poynting vectors on the B0 direction with increasing latitude. Also, wave vectors become most often more field aligned. A smaller group of chorus generated with very oblique wave normals tends to stay close to the whistler mode resonance cone. This suggests that close to the equatorial source region (within ˜20∘ latitude), a wave guidance mechanism is relevant, for example, in ducts of depleted or enhanced plasma density.
GPU Accelerated Vector Median Filter
NASA Technical Reports Server (NTRS)
Aras, Rifat; Shen, Yuzhong
2011-01-01
Noise reduction is an important step for most image processing tasks. For three channel color images, a widely used technique is vector median filter in which color values of pixels are treated as 3-component vectors. Vector median filters are computationally expensive; for a window size of n x n, each of the n(sup 2) vectors has to be compared with other n(sup 2) - 1 vectors in distances. General purpose computation on graphics processing units (GPUs) is the paradigm of utilizing high-performance many-core GPU architectures for computation tasks that are normally handled by CPUs. In this work. NVIDIA's Compute Unified Device Architecture (CUDA) paradigm is used to accelerate vector median filtering. which has to the best of our knowledge never been done before. The performance of GPU accelerated vector median filter is compared to that of the CPU and MPI-based versions for different image and window sizes, Initial findings of the study showed 100x improvement of performance of vector median filter implementation on GPUs over CPU implementations and further speed-up is expected after more extensive optimizations of the GPU algorithm .
Sparse Elimination on Vector Multiprocessors.
2014-09-26
vector registers . Several reports have been prepared recently under this effort, and a paper entitled "Task Granularity Studies in a Many-Processor Cray X...measures this effect. To reduce this ratio, it has been shown * possible to assembly-code the X-MP so that accesses are pre-fetched into vector registers
Vectors on the Basketball Court
ERIC Educational Resources Information Center
Bergman, Daniel
2010-01-01
An Idea Bank published in the April/May 2009 issue of "The Science Teacher" describes an experiential physics lesson on vectors and vector addition (Brown 2009). Like its football predecessor, the basketball-based investigation presented in this Idea Bank addresses National Science Education Standards Content B, Physical Science, 9-12 (NRC 1996)…
Vectors on the Basketball Court
ERIC Educational Resources Information Center
Bergman, Daniel
2010-01-01
An Idea Bank published in the April/May 2009 issue of "The Science Teacher" describes an experiential physics lesson on vectors and vector addition (Brown 2009). Like its football predecessor, the basketball-based investigation presented in this Idea Bank addresses National Science Education Standards Content B, Physical Science, 9-12 (NRC 1996)…
Divergence-based vector quantization.
Villmann, Thomas; Haase, Sven
2011-05-01
Supervised and unsupervised vector quantization methods for classification and clustering traditionally use dissimilarities, frequently taken as Euclidean distances. In this article, we investigate the applicability of divergences instead, focusing on online learning. We deduce the mathematical fundamentals for its utilization in gradient-based online vector quantization algorithms. It bears on the generalized derivatives of the divergences known as Fréchet derivatives in functional analysis, which reduces in finite-dimensional problems to partial derivatives in a natural way. We demonstrate the application of this methodology for widely applied supervised and unsupervised online vector quantization schemes, including self-organizing maps, neural gas, and learning vector quantization. Additionally, principles for hyperparameter optimization and relevance learning for parameterized divergences in the case of supervised vector quantization are given to achieve improved classification accuracy.
Chikungunya Virus–Vector Interactions
Coffey, Lark L.; Failloux, Anna-Bella; Weaver, Scott C.
2014-01-01
Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes chikungunya fever, a severe, debilitating disease that often produces chronic arthralgia. Since 2004, CHIKV has emerged in Africa, Indian Ocean islands, Asia, Europe, and the Americas, causing millions of human infections. Central to understanding CHIKV emergence is knowledge of the natural ecology of transmission and vector infection dynamics. This review presents current understanding of CHIKV infection dynamics in mosquito vectors and its relationship to human disease emergence. The following topics are reviewed: CHIKV infection and vector life history traits including transmission cycles, genetic origins, distribution, emergence and spread, dispersal, vector competence, vector immunity and microbial interactions, and co-infection by CHIKV and other arboviruses. The genetics of vector susceptibility and host range changes, population heterogeneity and selection for the fittest viral genomes, dual host cycling and its impact on CHIKV adaptation, viral bottlenecks and intrahost diversity, and adaptive constraints on CHIKV evolution are also discussed. The potential for CHIKV re-emergence and expansion into new areas and prospects for prevention via vector control are also briefly reviewed. PMID:25421891
Vector fields in multidimensional cosmology
NASA Astrophysics Data System (ADS)
Meierovich, Boris E.
2011-09-01
Vector fields in the expanding Universe are considered within the multidimensional theory of general relativity. Vector fields in general relativity form a three-parametric variety. Our consideration includes the fields with a nonzero covariant divergence. Depending on the relations between the particular parameters and the symmetry of a problem, the vector fields can be longitudinal and/or transverse, ultrarelativistic (i.e. massless) or nonrelativistic (massive), and so on. The longitudinal and transverse vector fields are considered separately in detail in the background of the de Sitter cosmological metric. In most cases the field equations reduce to Bessel equations, and their temporal evolution is analyzed analytically. The energy-momentum tensor of the most simple zero-mass longitudinal vector fields enters the Einstein equations as an additive to the cosmological constant. In this case the de Sitter metric is the exact solution of the Einstein equations. Hence, the most simple zero-mass longitudinal vector field pretends to be an adequate tool for macroscopic description of dark energy as a source of the expansion of the Universe at a constant rate. The zero-mass vector field does not vanish in the process of expansion. On the contrary, massive fields vanish with time. Though their amplitude is falling down, the massive fields make the expansion accelerated.
On Potential Vorticity Flux Vectors.
NASA Astrophysics Data System (ADS)
Bannon, Peter R.; Schmidli, Jürg; Schär, Christoph
2003-12-01
Dynamical, rather than kinematical, considerations indicate that a generalized potential vorticity in terms of the gradient of an arbitrary scalar function requires that the potential vorticity flux vector contain a contribution due to gravity and the pressure gradient force. It is shown that such a potential vorticity flux vector has a simpler definition in terms of the gradient of the kinetic energy rather than that of a Bernoulli function. This result is valid for multicomponent fluids. Flux vectors for a salty ocean and a moist atmosphere with hydrometeors are presented.
Vector statistics of LANDSAT imagery
NASA Technical Reports Server (NTRS)
Jayroe, R. R., Jr.; Underwood, D.
1977-01-01
A digitized multispectral image, such as LANDSAT data, is composed of numerous four dimensional vectors, which quantitatively describe the ground scene from which the data are acquired. The statistics of unique vectors that occur in LANDSAT imagery are studied to determine if that information can provide some guidance on reducing image processing costs. A second purpose of this report is to investigate how the vector statistics are changed by various types of image processing techniques and determine if that information can be useful in choosing one processing approach over another.
Insecticide resistance and vector control.
Brogdon, W. G.; McAllister, J. C.
1998-01-01
Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations. We describe the mechanisms of insecticide resistance, as well as specific instances of resistance emergence worldwide, and discuss prospects for resistance management and priorities for detection and surveillance. PMID:9866736
Relativistic Gamow vectors: State vectors for unstable particles
NASA Astrophysics Data System (ADS)
Kaldas, Hany Kamel Halim
The relativistic Gamow vectors are derived from the analytic continuation of the angular momentum velocity kets to the resonance pole of the S- matrix. This construction is justifiable within a Rigged Hilbert Space of Hardy class functions. The kets obtained | p j3[
Vector independent transmission of the vector-borne bluetongue virus.
van der Sluijs, Mirjam Tineke Willemijn; de Smit, Abraham J; Moormann, Rob J M
2016-01-01
Bluetongue is an economically important disease of ruminants. The causative agent, Bluetongue virus (BTV), is mainly transmitted by insect vectors. This review focuses on vector-free BTV transmission, and its epizootic and economic consequences. Vector-free transmission can either be vertical, from dam to fetus, or horizontal via direct contract. For several BTV-serotypes, vertical (transplacental) transmission has been described, resulting in severe congenital malformations. Transplacental transmission had been mainly associated with live vaccine strains. Yet, the European BTV-8 strain demonstrated a high incidence of transplacental transmission in natural circumstances. The relevance of transplacental transmission for the epizootiology is considered limited, especially in enzootic areas. However, transplacental transmission can have a substantial economic impact due to the loss of progeny. Inactivated vaccines have demonstrated to prevent transplacental transmission. Vector-free horizontal transmission has also been demonstrated. Since direct horizontal transmission requires close contact of animals, it is considered only relevant for within-farm spreading of BTV. The genetic determinants which enable vector-free transmission are present in virus strains circulating in the field. More research into the genetic changes which enable vector-free transmission is essential to better evaluate the risks associated with outbreaks of new BTV serotypes and to design more appropriate control measures.
Are Bred Vectors The Same As Lyapunov Vectors?
NASA Astrophysics Data System (ADS)
Kalnay, E.; Corazza, M.; Cai, M.
Regional loss of predictability is an indication of the instability of the underlying flow, where small errors in the initial conditions (or imperfections in the model) grow to large amplitudes in finite times. The stability properties of evolving flows have been studied using Lyapunov vectors (e.g., Alligood et al, 1996, Ott, 1993, Kalnay, 2002), singular vectors (e.g., Lorenz, 1965, Farrell, 1988, Molteni and Palmer, 1993), and, more recently, with bred vectors (e.g., Szunyogh et al, 1997, Cai et al, 2001). Bred vectors (BVs) are, by construction, closely related to Lyapunov vectors (LVs). In fact, after an infinitely long breeding time, and with the use of infinitesimal ampli- tudes, bred vectors are identical to leading Lyapunov vectors. In practical applications, however, bred vectors are different from Lyapunov vectors in two important ways: a) bred vectors are never globally orthogonalized and are intrinsically local in space and time, and b) they are finite-amplitude, finite-time vectors. These two differences are very significant in a dynamical system whose size is very large. For example, the at- mosphere is large enough to have "room" for several synoptic scale instabilities (e.g., storms) to develop independently in different regions (say, North America and Aus- tralia), and it is complex enough to have several different possible types of instabilities (such as barotropic, baroclinic, convective, and even Brownian motion). Bred vectors share some of their properties with leading LVs (Corazza et al, 2001a, 2001b, Toth and Kalnay, 1993, 1997, Cai et al, 2001). For example, 1) Bred vectors are independent of the norm used to define the size of the perturba- tion. Corazza et al. (2001) showed that bred vectors obtained using a potential enstro- phy norm were indistinguishable from bred vectors obtained using a streamfunction squared norm, in contrast with singular vectors. 2) Bred vectors are independent of the length of the rescaling period as long as the
Motion vector quantization for video coding.
Lee, Y Y; Woods, J W
1995-01-01
A new algorithm is developed for the vector quantization of motion vectors. This algorithm, called motion vector quantization (MVQ), simultaneously estimates and vector quantizes the motion vectors by reinterpreting the block matching algorithm as a type of vector quantization. An iterative design algorithm, based on this concept, is developed. In addition to reducing rate for fixed length encoding, the algorithm also reduces the computation considerably. We include coding simulation results on the Flower Garden sequence.
Integrated Thrust Vectored Engine Control
2001-06-01
erformances operationnelles des aeronefs militaires, des vehicules terrestres et des vehicules maritimes] To order the complete compilation report...throttling "* Autonomous Engine Configuration Side forces demand to define nozzle vectoring "* Simple Interface FADEC -> FCS " Minimum Interaction FCS
Disease Vector Ecology Profile: Colombia
1998-12-01
Studies of Mosquitoes of the Genus Haemagogus in Colombia (Diptera, Culicidae). Am. J. Hyg., 43: 13-28. Lane, J. 1953. Neotropical Culicidae...malariae and P. ovale). Female mosquitoes of the genus Anopheles are the exclusive vectors of human malaria. During feeding, the mosquito ingests...birds are implicated reservoirs. The biting midge, Culicoides paraensis, is a proven vector. Culex quinquefasciatus is also capable of transmission
Disease Vector Ecology Profile: Bolivia
1998-12-01
Arnell, J.H. 1973. Mosquito Studies (Diptera, Culicidae). XXXII. A Revision of the Genus Haemagogus. Contrib. Am. Ent. Inst., 10(2): 1-174...parasites (P. vivax , P. falciparum, P. malariae and P. ovale). Female mosquitoes of the genus Anopheles are the exclusive vectors of human malaria...and possibly wild birds are implicated reservoirs. The biting midge, Culicoides paraensis, is a proven vector. Culex quinquefasciatus is also
Hagedorn, Claudia; Baiker, Armin; Postberg, Jan; Ehrhardt, Anja; Lipps, Hans J
2012-06-01
Nonviral episomal vectors represent attractive alternatives to currently used virus-based expression systems. In the late 1990s, it was shown that a plasmid containing an expression cassette linked to a scaffold/matrix attached region (S/MAR) replicates as a low copy number episome in all cell lines tested, as well as primary cells, and can be used for the genetic modification of higher animals. Once established in the cell, the S/MAR vector replicates early during S-phase and, in the absence of selection, is stably retained in the cells for an unlimited period of time. This vector can therefore be regarded as a minimal model system for studying the epigenetic regulation of replication and functional nuclear architecture. In theory, this construct represents an almost "ideal" expression system for gene therapy. In practice, S/MAR-based vectors stably modify mammalian cells with efficiencies far below those of virus-based constructs. Consequently, they have not yet found application in gene therapy trials. Furthermore, S/MAR vector systems are not trivial to handle and several critical technical issues have to be considered when modifying these vectors for various applications.
Axisymmetric Coanda-assisted vectoring
NASA Astrophysics Data System (ADS)
Allen, Dustin; Smith, Barton L.
2009-01-01
An experimental demonstration of a jet vectoring technique used in our novel spray method called Coanda-assisted Spray Manipulation (CSM) is presented. CSM makes use of the Coanda effect on axisymmetric geometries through the interaction of two jets: a primary jet and a control jet. The primary jet has larger volume flow rate but generally a smaller momentum flux than the control jet. The primary jet flows through the center of a rounded collar. The control jet is parallel to the primary and is adjacent to the convex collar. The Reynolds number range for the primary jet at the exit plane was between 20,000 and 80,000. The flow was in the incompressible Mach number range (Mach < 0.3). The control jet attaches to the convex wall and vectors according to known Coanda effect principles, entraining and vectoring the primary jet, resulting in controllable r - θ directional spraying. Several annular control slots and collar radii were tested over a range of momentum flux ratios to determine the effects of these variables on the vectored jet angle and spreading. Two and Three-component Particle Image Velocimetry systems were used to determine the vectoring angle and the profile of the combined jet in each experiment. The experiments show that the control slot and expansion radius, along with the momentum ratios of the two jets predominantly affected the vectoring angle and profile of the combined jets.
Vector control after malaria eradication
Micks, D. W.
1963-01-01
In considerable areas now in or near the consolidation phase of malaria eradication, other vector-borne diseases present serious public health problems, even though not susceptible to control on the same world-wide scale as malaria. Several of these areas are already making plans for converting their malaria eradication services to vector control services. While it is possible to use essentially the same personnel and equipment, the methods must be adapted to the biology and habits of the vector. For a smooth and rapid transition, considerable advance planning is therefore needed—preferably well ahead of the consolidation phase. The author gives several examples of the need for flexibility in effecting the changeover and of the problems likely to arise after the completion of malaria eradication programmes. He recommends that epidemiological studies should be extended to vector-borne diseases other than malaria while eradication programmes are still in progress and that vector control programmes should be integrated into the basic health services of the country as soon as possible. He also underlines the importance of water management and other aspects of environmental sanitation in vector control programmes. PMID:20604169
Sustained expression from DNA vectors.
Wong, Suet Ping; Argyros, Orestis; Harbottle, Richard P
2015-01-01
DNA vectors have the potential to become powerful medical tools for treatment of human disease. The human body has, however, developed a range of defensive strategies to detect and silence foreign or misplaced DNA, which is more typically encountered during infection or chromosomal damage. A clinically relevant human gene therapy vector must overcome or avoid these protections whilst delivering sustained levels of therapeutic gene product without compromising the vitality of the recipient host. Many non-viral DNA vectors trigger these defense mechanisms and are subsequently destroyed or rendered silent. Thus, without modification or considered design, the clinical utility of a typical DNA vector is fundamentally limited due to the transient nature of its transgene expression. The development of safe and persistently expressing DNA vectors is a crucial prerequisite for its successful clinical application and subsequently remains, therefore, one of the main strategic tasks of non-viral gene therapy research. In this chapter we will describe our current understanding of the mechanisms that can destroy or silence DNA vectors and discuss strategies, which have been utilized to improve their sustenance and the level and duration of their transgene expression.
NASA Astrophysics Data System (ADS)
Giacosa, Francesco; Sammet, Julia; Janowski, Stanislaus
2017-06-01
We calculate two- and three-body decays of the (lightest) vector glueball into (pseudo)scalar, (axial-)vector, as well as pseudovector and excited vector mesons in the framework of a model of QCD. While absolute values of widths cannot be predicted because the corresponding coupling constants are unknown, some interesting branching ratios can be evaluated by setting the mass of the yet hypothetical vector glueball to 3.8 GeV as predicted by quenched lattice QCD. We find that the decay mode ω π π should be one of the largest (both through the decay chain O →b1π →ω π π and through the direct coupling O →ω π π ). Similarly, the (direct and indirect) decay into π K K*(892 ) is sizable. Moreover, the decays into ρ π and K*(892 )K are, although subleading, possible and could play a role in explaining the ρ π puzzle of the charmonium state ψ (2 S ) thanks to a (small) mixing with the vector glueball. The vector glueball can be directly formed at the ongoing BESIII experiment as well as at the future PANDA experiment at the FAIR facility. If the width is sufficiently small (≲100 MeV ) it should not escape future detection. It should be stressed that the employed model is based on some inputs and simplifying assumptions: the value of glueball mass (at present, the quenched lattice value is used), the lack of mixing of the glueball with other quarkonium states, and the use of few interaction terms. It then represents a first step toward the identification of the main decay channels of the vector glueball, but shall be improved when corresponding experimental candidates and/or new lattice results will be available.
NASA Astrophysics Data System (ADS)
Fan, Zhong-Ying
2016-09-01
In this paper, we consider Einstein gravity coupled to a vector field, either minimally or non-minimally, together with a vector potential of the type V = 2{Λ}_0+1/2{m}^2{A}^2 + {γ}_4{A}^4 . For a simpler non-minimally coupled theory with Λ0 = m = γ4 = 0, we obtain both extremal and non-extremal black hole solutions that are asymptotic to Minkowski space-times. We study the global properties of the solutions and derive the first law of thermodynamics using Wald formalism. We find that the thermodynamical first law of the extremal black holes is modified by a one form associated with the vector field. In particular, due to the existence of the non-minimal coupling, the vector forms thermodynamic conjugates with the graviton mode and partly contributes to the one form modifying the first law. For a minimally coupled theory with Λ0 ≠ 0, we also obtain one class of asymptotically flat extremal black hole solutions in general dimensions. This is possible because the parameters ( m 2 , γ4) take certain values such that V = 0. In particular, we find that the vector also forms thermodynamic conjugates with the graviton mode and contributes to the corresponding first law, although the non-minimal coupling has been turned off. Thus all the extremal black hole solutions that we obtain provide highly non-trivial examples how the first law of thermodynamics can be modified by a either minimally or non-minimally coupled vector field. We also study Gauss-Bonnet gravity non-minimally coupled to a vector and obtain asymptotically flat black holes and Lifshitz black holes.
Learning with LOGO: Logo and Vectors.
ERIC Educational Resources Information Center
Lough, Tom; Tipps, Steve
1986-01-01
This is the first of a two-part series on the general concept of vector space. Provides tool procedures to allow investigation of vector properties, vector addition and subtraction, and X and Y components. Lists several sources of additional vector ideas. (JM)
The biological control of disease vectors.
Okamoto, Kenichi W; Amarasekare, Priyanga
2012-09-21
Vector-borne diseases are common in nature and can have a large impact on humans, livestock and crops. Biological control of vectors using natural enemies or competitors can reduce vector density and hence disease transmission. However, the indirect interactions inherent in host-vector disease systems make it difficult to use traditional pest control theory to guide biological control of disease vectors. This necessitates a conceptual framework that explicitly considers a range of indirect interactions between the host-vector disease system and the vector's biological control agent. Here we conduct a comparative analysis of the efficacy of different types of biological control agents in controlling vector-borne diseases. We report three key findings. First, highly efficient predators and parasitoids of the vector prove to be effective biological control agents, but highly virulent pathogens of the vector also require a high transmission rate to be effective. Second, biocontrol agents can successfully reduce long-term host disease incidence even though they may fail to reduce long-term vector densities. Third, inundating a host-vector disease system with a natural enemy of the vector has little or no effect on reducing disease incidence, but inundating the system with a competitor of the vector has a large effect on reducing disease incidence. The comparative framework yields predictions that are useful in developing biological control strategies for vector-borne diseases. We discuss how these predictions can inform ongoing biological control efforts for host-vector disease systems. Copyright © 2012. Published by Elsevier Ltd.
Vector quantization and learning vector quantization for radar target classification
NASA Astrophysics Data System (ADS)
Stewart, Clayton V.; Lu, Yi-Chuan; Larson, Victor J.
1993-10-01
Radar target classification performance is greatly dependent on how the classifier represents the strongly angle dependent radar target signatures. This paper compares the performance of classifiers that represent radar target signatures using vector quantization (VQ) and learning vector quantization (LVQ). The classifier performance is evaluated with a set of high resolution millimeter-wave radar data from four ground vehicles (Camaro, van, pickup, and bulldozer). LVQ explicitly includes classification performance in its data representation criterion, whereas VQ only makes use of a distortion measure such as mean square distance. The classifier that uses LVQ to represent the radar data has a much higher probability of correct classification than VQ.
Vector control in developed countries
Peters, Richard F.
1963-01-01
The recent rapid growth of California's population, leading to competition for space between residential, industrial and agricultural interests, the development of its water resources and increasing water pollution provide the basic ingredients of its present vector problems. Within the past half-century, the original mosquito habitats provided by nature have gradually given place to even more numerous and productive habitats of man-made character. At the same time, emphasis in mosquito control has shifted from physical to chemical, with the more recent extension to biological approaches as well. The growing domestic fly problem, continuing despite the virtual disappearance of the horse, is attributable to an increasing amount of organic by-products, stemming from growing communities, expanding industries and changing agriculture. The programme for the control of disease vectors and pest insects and animals directs its major effort to the following broad areas: (1) water management (including land preparation), (2) solid organic wastes management (emphasizing utilization), (3) community management (including design, layout, and storage practices of buildings and grounds), and (4) recreational area management (related to wildlife management). It is apparent that vector control can often employ economics as an ally in securing its objectives. Effective organization of the environment to produce maximum economic benefits to industry, agriculture, and the community results generally in conditions unfavourable to the survival of vector and noxious animal species. Hence, vector prevention or suppression is preferable to control as a programme objective. PMID:20604166
Vectors for cancer gene therapy.
Zhang, J; Russell, S J
1996-09-01
Many viral and non-viral vector systems have now been developed for gene therapy applications. In this article, the pros and cons of these vector systems are discussed in relation to the different cancer gene therapy strategies. The protocols used in cancer gene therapy can be broadly divided into six categories including gene transfer to explanted cells for use as cell-based cancer vaccines; gene transfer to a small number of tumour cells in situ to achieve a vaccine effect; gene transfer to vascular endothelial cells (VECs) lining the blood vessels of the tumour to interfere with tumour angiogenesis; gene transfer to T lymphocytes to enhance their antitumour effector capability; gene transfer to haemopoietic stem cells (HSCs) to enhance their resistance to cytotoxic drugs and gene transfer to a large number of tumour cells in situ to achieve nonimmune tumour reduction with or without bystander effect. Each of the six strategies makes unique demands on the vector system and these are discussed with reference to currently available vectors. Aspects of vector biology that are in need of further development are discussed in some detail. The final section points to the potential use of replicating viruses as delivery vehicles for efficient in vivo gene transfer to disseminated cancers.
A generalized nonlocal vector calculus
NASA Astrophysics Data System (ADS)
Alali, Bacim; Liu, Kuo; Gunzburger, Max
2015-10-01
A nonlocal vector calculus was introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) that has proved useful for the analysis of the peridynamics model of nonlocal mechanics and nonlocal diffusion models. A formulation is developed that provides a more general setting for the nonlocal vector calculus that is independent of particular nonlocal models. It is shown that general nonlocal calculus operators are integral operators with specific integral kernels. General nonlocal calculus properties are developed, including nonlocal integration by parts formula and Green's identities. The nonlocal vector calculus introduced in Du et al. (Math Model Meth Appl Sci 23:493-540, 2013) is shown to be recoverable from the general formulation as a special example. This special nonlocal vector calculus is used to reformulate the peridynamics equation of motion in terms of the nonlocal gradient operator and its adjoint. A new example of nonlocal vector calculus operators is introduced, which shows the potential use of the general formulation for general nonlocal models.
Episomal vectors for gene therapy.
Ehrhardt, Anja; Haase, Rudolf; Schepers, Aloys; Deutsch, Manuel J; Lipps, Hans Joachim; Baiker, Armin
2008-06-01
The increasing knowledge of the molecular and genetic background of many different human diseases has led to the vision that genetic engineering might be used one day for their phenotypic correction. The main goal of gene therapy is to treat loss-of-function genetic disorders by delivering correcting therapeutic DNA sequences into the nucleus of a cell, allowing its long-term expression at physiologically relevant levels. Manifold different vector systems for the therapeutic gene delivery have been described over the recent years. They all have their individual advantages but also their individual limitations and must be judged on a careful risk/benefit analysis. Integrating vector systems can deliver genetic material to a target cell with high efficiency enabling long-term expression of an encoded transgene. The main disadvantage of integrating vector systems, however, is their potential risk of causing insertional mutagenesis. Episomal vector systems have the potential to avoid these undesired side effects, since they behave as separate extrachromosomal elements in the nucleus of a target cell. Within this article we present a comprehensive survey of currently available episomal vector systems for the genetic modification of mammalian cells. We will discuss their advantages and disadvantages and their applications in the context of basic research, biotechnology and gene therapy.
Vector Encoding in Biochemical Networks
NASA Astrophysics Data System (ADS)
Potter, Garrett; Sun, Bo
Encoding of environmental cues via biochemical signaling pathways is of vital importance in the transmission of information for cells in a network. The current literature assumes a single cell state is used to encode information, however, recent research suggests the optimal strategy utilizes a vector of cell states sampled at various time points. To elucidate the optimal sampling strategy for vector encoding, we take an information theoretic approach and determine the mutual information of the calcium signaling dynamics obtained from fibroblast cells perturbed with different concentrations of ATP. Specifically, we analyze the sampling strategies under the cases of fixed and non-fixed vector dimension as well as the efficiency of these strategies. Our results show that sampling with greater frequency is optimal in the case of non-fixed vector dimension but that, in general, a lower sampling frequency is best from both a fixed vector dimension and efficiency standpoint. Further, we find the use of a simple modified Ornstein-Uhlenbeck process as a model qualitatively captures many of our experimental results suggesting that sampling in biochemical networks is based on a few basic components.
Generalized Selection Weighted Vector Filters
NASA Astrophysics Data System (ADS)
Lukac, Rastislav; Plataniotis, Konstantinos N.; Smolka, Bogdan; Venetsanopoulos, Anastasios N.
2004-12-01
This paper introduces a class of nonlinear multichannel filters capable of removing impulsive noise in color images. The here-proposed generalized selection weighted vector filter class constitutes a powerful filtering framework for multichannel signal processing. Previously defined multichannel filters such as vector median filter, basic vector directional filter, directional-distance filter, weighted vector median filters, and weighted vector directional filters are treated from a global viewpoint using the proposed framework. Robust order-statistic concepts and increased degree of freedom in filter design make the proposed method attractive for a variety of applications. Introduced multichannel sigmoidal adaptation of the filter parameters and its modifications allow to accommodate the filter parameters to varying signal and noise statistics. Simulation studies reported in this paper indicate that the proposed filter class is computationally attractive, yields excellent performance, and is able to preserve fine details and color information while efficiently suppressing impulsive noise. This paper is an extended version of the paper by Lukac et al. presented at the 2003 IEEE-EURASIP Workshop on Nonlinear Signal and Image Processing (NSIP '03) in Grado, Italy.
Gauge Theories of Vector Particles
DOE R&D Accomplishments Database
Glashow, S. L.; Gell-Mann, M.
1961-04-24
The possibility of generalizing the Yang-Mills trick is examined. Thus we seek theories of vector bosons invariant under continuous groups of coordinate-dependent linear transformations. All such theories may be expressed as superpositions of certain "simple" theories; we show that each "simple theory is associated with a simple Lie algebra. We may introduce mass terms for the vector bosons at the price of destroying the gauge-invariance for coordinate-dependent gauge functions. The theories corresponding to three particular simple Lie algebras - those which admit precisely two commuting quantum numbers - are examined in some detail as examples. One of them might play a role in the physics of the strong interactions if there is an underlying super-symmetry, transcending charge independence, that is badly broken. The intermediate vector boson theory of weak interactions is discussed also. The so-called "schizon" model cannot be made to conform to the requirements of partial gauge-invariance.
Extrapolation methods for vector sequences
NASA Technical Reports Server (NTRS)
Smith, David A.; Ford, William F.; Sidi, Avram
1987-01-01
This paper derives, describes, and compares five extrapolation methods for accelerating convergence of vector sequences or transforming divergent vector sequences to convergent ones. These methods are the scalar epsilon algorithm (SEA), vector epsilon algorithm (VEA), topological epsilon algorithm (TEA), minimal polynomial extrapolation (MPE), and reduced rank extrapolation (RRE). MPE and RRE are first derived and proven to give the exact solution for the right 'essential degree' k. Then, Brezinski's (1975) generalization of the Shanks-Schmidt transform is presented; the generalized form leads from systems of equations to TEA. The necessary connections are then made with SEA and VEA. The algorithms are extended to the nonlinear case by cycling, the error analysis for MPE and VEA is sketched, and the theoretical support for quadratic convergence is discussed. Strategies for practical implementation of the methods are considered.
NASA Astrophysics Data System (ADS)
Hosaka, A.; Toki, H.; Weise, W.
1990-01-01
We investigate nucleon structure in a (non-linear) chiral bag model with vector mesons. The model incorporates two different degrees of freedom: mesons outside the bag at long and intermediate ranges, and quarks inside the bag at short distances. The ρ, a 1 and ω mesons outside the bag are included in a chiral effective lagrangian based on the non-linear sigma model. The classical solution is obtained using the hedgehog ansatz, and the cranking method is applied to construct the physical nucleon states. Static properties of the nucleon such as its mass, axial vector coupling constant, magnetic moments and charge radii are studied in detail as functions of the bag radius. Quark and meson contributions to these quantities are calculated separately. In particular, we discuss the extent to which the vector-meson dominance picture holds in the chiral bag.
Vector insects and their control.
Lehane, M J
1996-01-01
This paper emphasizes the huge influence that vector-transmitted disease has on humans using plague, epidemic typhus and nagana as examples. The continuing need for vector control in campaigns against insect-transmitted disease is shown by reference to current control programmes mounted against Chagas' disease, onchocerciasis, lymphatic filariasis and nagana. These successful campaigns have not been reliant on new breakthroughs but on the forging of available tools into effective strategies widely and efficiently used by the control authorities, and the long-lasting political commitment to the success of the schemes in question. A brief mention is made of current fashions in vector control research and that great care needs to be taken by policy-makers to achieve a balance between long-term research aiming at the production of fundamentally new control technologies and operational research aiming to forge the often highly effective tools we already have into sound control strategies.
Targeting retroviral and lentiviral vectors.
Sandrin, V; Russell, S J; Cosset, F L
2003-01-01
Retroviral vectors capable of efficient in vivo gene delivery to specific target cell types or to specific locations of disease pathology would greatly facilitate many gene therapy applications. The surface glycoproteins of membrane-enveloped viruses stand among the choice candidates to control the target cell receptor recognition and host range of retroviral vectors onto which they are incorporated. This can be achieved in many ways, such as the exchange of glycoprotein by pseudotyping, their biochemical modifications, their conjugation with virus-cell bridging agents or their structural modifications. Understanding the fundamental properties of the viral glycoproteins and the molecular mechanism of virus entry into cells has been instrumental in the functional alteration of their tropism. Here we briefly review the current state of our understanding of the structure and function of viral envelope glycoproteins and we discuss the emerging targeting strategies based on retroviral and lentiviral vector systems.
Bred vectors, singular vectors, and Lyapunov vectors in simple and complex models
NASA Astrophysics Data System (ADS)
Norwood, Adrienne
We compute and compare three types of vectors frequently used to explore the instability properties of dynamical models, Lyapunov vectors (LVs), singular vectors (SVs), and bred vectors (BVs). The first model is the Lorenz (1963) three-variable model. We find BVs align with the locally fastest growing LV, which is often the second fastest growing global LV. The growth rates of the three types of vectors reveal all predict regime changes and durations of new regimes, as shown for BVs by Evans et al. (2004). The second model is the toy 'atmosphere-ocean model' developed by Pena and Kalnay (2004) coupling three Lorenz (1963) models with different time scales to test the effects of fast and slow modes of growth on the dynamical vectors. A fast 'extratropical atmosphere' is weakly coupled to a fast 'tropical atmosphere' which is strongly coupled to a slow 'ocean' system, the latter coupling imitating the tropical El Nino--Southern Oscillation. BVs separate the fast and slow modes of growth through appropriate selection of the breeding parameters. LVs successfully separate the fast 'extratropics' but cannot completely decouple the 'tropics' from the 'ocean,' leading to 'coupled' LVs that are affected by both systems but mainly dominated by one. SVs identify the fast modes but cannot capture the slow modes until the fast 'extratropics' are replaced with faster 'convection.' The dissimilar behavior of the three types of vectors degrades the similarities of the subspaces they inhabit (Norwood et al. 2013). The third model is a quasi-geostrophic channel model (Rotunno and Bao 1996) that is a simplification of extratropical synoptic-scale motions with baroclinic instabilities only. We were unable to successfully compute LVs for it. However, randomly initialized BVs quickly converge to a single vector that is the leading LV. The last model is the SPEEDY model created by Molteni (2003). It is a simplified general atmospheric circulation model with several types of instabilities
Thrust-vectored differential turns
NASA Technical Reports Server (NTRS)
Kelley, H. J.; Cliff, E. M.; Lefton, L.
1980-01-01
Barrier surface construction in the joint space of the differential turning game for thrust-vectored vs. conventional aircraft is discussed. Differential-turn studies are based on modifications of existing computer programs including an energy-turn program, and one which generates hodograph data. Optimal turning flight in energy approximation is discussed for the conventional aircraft configurations. It is concluded that any advantages realized from thrust-vectoring are minor, unless hover is possible, where advantages would be major at low energies, and affect tactics at high energies as well.
Anisotropic inflation from vector impurity
Kanno, Sugumi; Kimura, Masashi; Soda, Jiro; Yokoyama, Shuichiro E-mail: mkimura@sci.osaka-cu.ac.jp E-mail: shu@a.phys.nagoya-u.ac.jp
2008-08-15
We study an inflationary scenario with a vector impurity. We show that the universe undergoes anisotropic inflationary expansion due to a preferred direction determined by the vector. Using the slow roll approximation, we find a formula for determining the anisotropy of the inflationary universe. We discuss possible observable predictions of this scenario. In particular, it is stressed that primordial gravitational waves can be induced from curvature perturbations. Hence, even in low scale inflation, a sizable amount of primordial gravitational waves may be produced during inflation.
Requirements for airborne vector gravimetry
NASA Technical Reports Server (NTRS)
Schwarz, K. P.; Colombo, O.; Hein, G.; Knickmeyer, E. T.
1992-01-01
The objective of airborne vector gravimetry is the determination of the full gravity disturbance vector along the aircraft trajectory. The paper briefly outlines the concept of this method using a combination of inertial and GPS-satellite data. The accuracy requirements for users in geodesy and solid earth geophysics, oceanography and exploration geophysics are then specified. Using these requirements, accuracy specifications for the GPS subsystem and the INS subsystem are developed. The integration of the subsystems and the problems connected with it are briefly discussed and operational methods are indicated that might reduce some of the stringent accuracy requirements.
Requirements for airborne vector gravimetry
NASA Technical Reports Server (NTRS)
Schwarz, K. P.; Colombo, O.; Hein, G.; Knickmeyer, E. T.
1992-01-01
The objective of airborne vector gravimetry is the determination of the full gravity disturbance vector along the aircraft trajectory. The paper briefly outlines the concept of this method using a combination of inertial and GPS-satellite data. The accuracy requirements for users in geodesy and solid earth geophysics, oceanography and exploration geophysics are then specified. Using these requirements, accuracy specifications for the GPS subsystem and the INS subsystem are developed. The integration of the subsystems and the problems connected with it are briefly discussed and operational methods are indicated that might reduce some of the stringent accuracy requirements.
Song, Y F; Zhang, H; Zhao, L M; Shen, D Y; Tang, D Y
2016-01-25
We report on the experimental observation of vector and bound vector solitons in a fiber laser passively mode locked by graphene. Localized interactions between vector solitons, vector soliton with bound vector solitons, and vector soliton with a bunch of vector solitons are experimentally investigated. We show that depending on the soliton interactions, various stable and dynamic multiple vector soliton states could be formed.
Paleomagnetic vectors and tilted dikes
NASA Astrophysics Data System (ADS)
Borradaile, G. J.
2001-04-01
Where tectonic deformation reorients rocks without penetrative strain, their paleomagnetic vectors may be restored to their original attitudes by untilting. For strata, paleomagnetic inclination is readily restored but the tilt axis must be precisely known if paleodeclination is required. For dikes, without the knowledge of the rotation(s), neither declination nor inclination of the paleomagnetic vector can be uniquely defined. Furthermore, back-rotating dike orientations to an upright attitude assumes primary verticality whereas primary dike dips are bimodal across the spreading axes (e.g. Troodos ophiolite, Cyprus). In the Cyprus ophiolite, the dikes of the Limassol Forest Transform Zone are tilted due to uplift of the mantle-sequence rocks and deflected against the Arakapas Fault. Their paleomagnetic vectors may be restored rotating about the two axes defined by the strike and the vertical, or about a net axis that is possibly the actual tectonic rotation axis. This net axis is determined from the tectonic regional dispersion of the dike orientations. In this test case, the results of the restorations differ slightly but underline the difficulty in selecting the best restoration procedure and the greater difficulty of restoring the paleomagnetic data from dikes vis à vis strata. For dikes, it is recommended that the paleomagnetic vectors are restored using average dike orientations to minimize the inaccuracies due to the large primary variation in dike orientation.
NASA Technical Reports Server (NTRS)
Powers, W. D.
1975-01-01
The feasibility of utilizing hydrogen as an energy vector is considered, with special attention given to means of hydrogen production. The state-of-the-art in thermochemical processes is reviewed, and criteria for the technical and economic feasibility of large-scale thermochemical water splitting processes are presented. The production of hydrogen from coal and from photolysis of water is discussed.
Portfolio Analysis for Vector Calculus
ERIC Educational Resources Information Center
Kaplan, Samuel R.
2015-01-01
Classic stock portfolio analysis provides an applied context for Lagrange multipliers that undergraduate students appreciate. Although modern methods of portfolio analysis are beyond the scope of vector calculus, classic methods reinforce the utility of this material. This paper discusses how to introduce classic stock portfolio analysis in a…
Vector ecology of equine piroplasmosis
USDA-ARS?s Scientific Manuscript database
Equine piroplasmosis (EP) is a disease of equidae including horses, donkeys, mules and zebras caused by either of two protozoan parasites, Theileria equi or Babesia caballi. These parasites are biologically transmitted between hosts via tick-vectors and although they have inherent differences, they ...
Phlebotomine Vectors of Human Disease.
1983-12-30
different. We refrain from naming this specimen until more material becomes available. 12. Lutzomyia olmeca bicolor Fairchild and Theodor 1971...Castillo (1958) and Arzube (1960). Lutzomyia olmeca bicolor is the suspected vector of Leishmania mexicana aristedesi among rodents and marsupials in
Primer vector theory and applications
NASA Technical Reports Server (NTRS)
Jezewski, D. J.
1975-01-01
A method developed to compute two-body, optimal, N-impulse trajectories was presented. The necessary conditions established define the gradient structure of the primer vector and its derivative for any set of boundary conditions and any number of impulses. Inequality constraints, a conjugate gradient iterator technique, and the use of a penalty function were also discussed.
Biosafety Features of Lentiviral Vectors
Schambach, Axel; Zychlinski, Daniela; Ehrnstroem, Birgitta
2013-01-01
Abstract Over the past decades, lentiviral vectors have evolved as a benchmark tool for stable gene transfer into cells with a high replicative potential. Their relatively flexible genome and ability to transduce many forms of nondividing cells, combined with the potential for cell-specific pseudotyping, provides a rich resource for numerous applications in experimental platforms and therapeutic settings. Here, we give an overview of important biosafety features of lentiviral vectors, with detailed discussion of (i) the principles of the lentiviral split-genome design used for the construction of packaging cells; (ii) the relevance of modifications introduced into the lentiviral long terminal repeat (deletion of enhancer/promoter sequences and introduction of insulators); (iii) the basic features of mRNA processing, including the Rev/Rev-responsive element (RRE) interaction and the modifications of the 3′ untranslated region of lentiviral vectors with various post-transcriptional regulatory elements affecting transcriptional termination, polyadenylation, and differentiation-specific degradation of mRNA; and (iv) the characteristic integration pattern with the associated risk of transcriptional interference with cellular genes. We conclude with considerations regarding the importance of cell targeting via envelope modifications. Along this course, we address canonical biosafety issues encountered with any type of viral vector: the risks of shedding, mobilization, germline transmission, immunogenicity, and insertional mutagenesis. PMID:23311447
Biosafety features of lentiviral vectors.
Schambach, Axel; Zychlinski, Daniela; Ehrnstroem, Birgitta; Baum, Christopher
2013-02-01
Over the past decades, lentiviral vectors have evolved as a benchmark tool for stable gene transfer into cells with a high replicative potential. Their relatively flexible genome and ability to transduce many forms of nondividing cells, combined with the potential for cell-specific pseudotyping, provides a rich resource for numerous applications in experimental platforms and therapeutic settings. Here, we give an overview of important biosafety features of lentiviral vectors, with detailed discussion of (i) the principles of the lentiviral split-genome design used for the construction of packaging cells; (ii) the relevance of modifications introduced into the lentiviral long terminal repeat (deletion of enhancer/promoter sequences and introduction of insulators); (iii) the basic features of mRNA processing, including the Rev/Rev-responsive element (RRE) interaction and the modifications of the 3' untranslated region of lentiviral vectors with various post-transcriptional regulatory elements affecting transcriptional termination, polyadenylation, and differentiation-specific degradation of mRNA; and (iv) the characteristic integration pattern with the associated risk of transcriptional interference with cellular genes. We conclude with considerations regarding the importance of cell targeting via envelope modifications. Along this course, we address canonical biosafety issues encountered with any type of viral vector: the risks of shedding, mobilization, germline transmission, immunogenicity, and insertional mutagenesis.
Portfolio Analysis for Vector Calculus
ERIC Educational Resources Information Center
Kaplan, Samuel R.
2015-01-01
Classic stock portfolio analysis provides an applied context for Lagrange multipliers that undergraduate students appreciate. Although modern methods of portfolio analysis are beyond the scope of vector calculus, classic methods reinforce the utility of this material. This paper discusses how to introduce classic stock portfolio analysis in a…
On third order integrable vector Hamiltonian equations
NASA Astrophysics Data System (ADS)
Meshkov, A. G.; Sokolov, V. V.
2017-03-01
A complete list of third order vector Hamiltonian equations with the Hamiltonian operator Dx having an infinite series of higher conservation laws is presented. A new vector integrable equation on the sphere is found.
Using Dip Vectors to Analyze Structural Data.
ERIC Educational Resources Information Center
Whisonant, Robert Clyde; Watts, Chester Frederick
1989-01-01
A method of plotting planes on stereonets is described including great circles, poles, and dip vectors. Teaching applications of dip vectors in engineering geology and structural geology are discussed. (CW)
Symbolic Vector Analysis in Plasma Physics
Qin, H.; Rewoldt, G.; Tang, W.M.
1997-10-01
Many problems in plasma physics involve substantial amounts of analytical vector calculation. The complexity usually originates from both the vector operations themselves and the choice of underlying coordinate system. A computer algebra package for symbolic vector analysis in general coordinate systems, GeneralVectorAnalysis (GVA), is developed using Mathematica. The modern viewpoint for 3D vector calculus, differential forms on 3-manifolds, is adopted to unify and systematize the vector calculus operations in general coordinate systems. This package will benefit physicists and applied mathematicians in their research where complicated vector analysis is required. It will not only save a huge amount of human brain-power and dramatically improve accuracy, but this package will also be an intelligent tool to assist researchers in finding the right approaches to their problems. Several applications of this symbolic vector analysis package to plasma physics are also given.
Symbolic Vector Analysis in Plasma Physics
Qin, H.; Tang, W.M.; Rewoldt, G.
1997-10-09
Many problems in plasma physics involve substantial amounts of analytical vector calculation. The complexity usually originates from both the vector operations themselves and the choice of underlying coordinate system. A computer algebra package for symbolic vector analysis in general coordinate systems, General Vector Analysis (GVA), is developed using Mathematica. The modern viewpoint for 3D vector calculus, differential forms on 3-manifolds, is adopted to unify and systematize the vector calculus operations in general coordinate systems. This package will benefit physicists and applied mathematicians in their research where complicated vector analysis is required. It will not only save a huge amount of human brain-power and dramatically improve accuracy, but this package will also be an intelligent tool to assist researchers in finding the right approaches to their problems. Several applications of this symbolic vector analysis package to plasma physics are also given.
Context vector approach to image retrieval
NASA Astrophysics Data System (ADS)
Ren, Clara Z.; Means, Robert W.
1998-04-01
HNC developed a unique context vector approach to image retrieval in Image Contrast Addressable Retrieval System. The basis for this approach is the context vector approach to image representation. A context vector is a high dimensional vector of real numbers, derived from a set of features that are useful in discriminating between images in a particular domain. The image features are trained based upon the constrained 2D self-organizing learning law. The image context vector encodes both intra-image features and inter-image relationship. The similarity in the directions of the context vectors of a pair of images indicates their similarity of content. The context vector approach to image representation simplifies the image and retrieval indexing problem because simple Euclidean distance measurements between sets of context vectors are used as a measure of similarity.
Vector computer memory bank contention
NASA Technical Reports Server (NTRS)
Bailey, D. H.
1985-01-01
A number of vector supercomputers feature very large memories. Unfortunately the large capacity memory chips that are used in these computers are much slower than the fast central processing unit (CPU) circuitry. As a result, memory bank reservation times (in CPU ticks) are much longer than on previous generations of computers. A consequence of these long reservation times is that memory bank contention is sharply increased, resulting in significantly lowered performance rates. The phenomenon of memory bank contention in vector computers is analyzed using both a Markov chain model and a Monte Carlo simulation program. The results of this analysis indicate that future generations of supercomputers must either employ much faster memory chips or else feature very large numbers of independent memory banks.
Vector computer memory bank contention
NASA Technical Reports Server (NTRS)
Bailey, David H.
1987-01-01
A number of vector supercomputers feature very large memories. Unfortunately the large capacity memory chips that are used in these computers are much slower than the fast central processing unit (CPU) circuitry. As a result, memory bank reservation times (in CPU ticks) are much longer than on previous generations of computers. A consequence of these long reservation times is that memory bank contention is sharply increased, resulting in significantly lowered performance rates. The phenomenon of memory bank contention in vector computers is analyzed using both a Markov chain model and a Monte Carlo simulation program. The results of this analysis indicate that future generations of supercomputers must either employ much faster memory chips or else feature very large numbers of independent memory banks.
Medium Modification of Vector Mesons
Chaden Djalali, Michael Paolone, Dennis Weygand, Michael H. Wood, Rakhsha Nasseripour
2011-03-01
The theory of the strong interaction, Quantum Chromodynamics (QCD), has been remarkably successful in describing high-energy and short-distance-scale experiments involving quarks and gluons. However, applying QCD to low energy and large-distance scale experiments has been a major challenge. Various QCD-inspired models predict a partial restoration of chiral symmetry in nuclear matter with modifications of the properties of hadrons from their free-space values. Measurable changes such as a shift in mass and/or a change of width are predicted at normal nuclear density. Photoproduction of vector mesons off nuclei have been performed at different laboratories. The properties of the ρ, ω and φ mesons are investigated either directly by measuring their mass spectra or indirectly through transparency ratios. The latest results regarding medium modifications of the vector mesons in the nuclear medium will be discussed.
Lentiviral vectors in cancer immunotherapy.
Oldham, Robyn Aa; Berinstein, Elliot M; Medin, Jeffrey A
2015-01-01
Basic science advances in cancer immunotherapy have resulted in various treatments that have recently shown success in the clinic. Many of these therapies require the insertion of genes into cells to directly kill them or to redirect the host's cells to induce potent immune responses. Other analogous therapies work by modifying effector cells for improved targeting and enhanced killing of tumor cells. Initial studies done using γ-retroviruses were promising, but safety concerns centered on the potential for insertional mutagenesis have highlighted the desire to develop other options for gene delivery. Lentiviral vectors (LVs) have been identified as potentially more effective and safer alternative delivery vehicles. LVs are now in use in clinical trials for many different types of inherited and acquired disorders, including cancer. This review will discuss current knowledge of LVs and the applications of this viral vector-based delivery vehicle to cancer immunotherapy.
Clinical applications of power vectors.
Miller, Joseph M
2009-06-01
The study of infant vision is closely coupled to the study of the refraction, change in refraction over time, and the effect of spectacle correction on visual development. Frequently, reports are limited to descriptions of spherical equivalent or cylinder power without regard to axis, as data are frequently collected in the clinical format of sphere, cylinder, and axis (S, C, A). Conversion from clinical notation to a power vector representation of refraction allows unambiguous description of how refractions change over time and differ between repeated measurements. This article presents a series of examples of Microsoft Excel spreadsheet formulas that make the conversion from clinical notation to power vector format, and provides examples of useful applications of these methods.
Fast combinatorial vector field topology.
Reininghaus, Jan; Löwen, Christian; Hotz, Ingrid
2011-10-01
This paper introduces a novel approximation algorithm for the fundamental graph problem of combinatorial vector field topology (CVT). CVT is a combinatorial approach based on a sound theoretical basis given by Forman's work on a discrete Morse theory for dynamical systems. A computational framework for this mathematical model of vector field topology has been developed recently. The applicability of this framework is however severely limited by the quadratic complexity of its main computational kernel. In this work, we present an approximation algorithm for CVT with a significantly lower complexity. This new algorithm reduces the runtime by several orders of magnitude and maintains the main advantages of CVT over the continuous approach. Due to the simplicity of our algorithm it can be easily parallelized to improve the runtime further. © 2011 IEEE
Vector computer memory bank contention
NASA Technical Reports Server (NTRS)
Bailey, David H.
1987-01-01
A number of vector supercomputers feature very large memories. Unfortunately the large capacity memory chips that are used in these computers are much slower than the fast central processing unit (CPU) circuitry. As a result, memory bank reservation times (in CPU ticks) are much longer than on previous generations of computers. A consequence of these long reservation times is that memory bank contention is sharply increased, resulting in significantly lowered performance rates. The phenomenon of memory bank contention in vector computers is analyzed using both a Markov chain model and a Monte Carlo simulation program. The results of this analysis indicate that future generations of supercomputers must either employ much faster memory chips or else feature very large numbers of independent memory banks.
Quantum electrodynamics for vector mesons.
Djukanovic, Dalibor; Schindler, Matthias R; Gegelia, Jambul; Scherer, Stefan
2005-07-01
Quantum electrodynamics for rho mesons is considered. It is shown that, at the tree level, the value of the gyromagnetic ratio of the rho+ is fixed to 2 in a self-consistent effective quantum field theory. Further, the mixing parameter of the photon and the neutral vector meson is equal to the ratio of electromagnetic and strong couplings, leading to the mass difference M(rho0)-M(rho+/-) approximately 1 MeV at tree order.
Disease Vector Ecology Profile: Ecuador
1998-12-01
Boshell-Manrique. 1946. Studies of Mosquitoes of the Genus Haemagogus in Colombia (Diptera, Culicidae). Am. J. Hyg., 43: 13-28. 75 Lane, J...Leishmaniasis is a protozoan disease transmitted in the New World by sand flies in the genus Lutzomyia. Most cases occur in the tropical and subtropical...parasites (P. vivax , P. falciparum, P. malariae and P. ovale). Female mosquitoes of the genus Anopheles are the exclusive vectors of human malaria
GAPS IN SUPPORT VECTOR OPTIMIZATION
STEINWART, INGO; HUSH, DON; SCOVEL, CLINT; LIST, NICOLAS
2007-01-29
We show that the stopping criteria used in many support vector machine (SVM) algorithms working on the dual can be interpreted as primal optimality bounds which in turn are known to be important for the statistical analysis of SVMs. To this end we revisit the duality theory underlying the derivation of the dual and show that in many interesting cases primal optimality bounds are the same as known dual optimality bounds.
A ocean bottom vector magnetometer
NASA Astrophysics Data System (ADS)
Wang, Xiaomei; Teng, Yuntian; Wang, Chen; Ma, Jiemei
2017-04-01
The new development instrument with a compact spherical coil system and Overhauser magnetometer for measuring the total strength of the magnetic field and the vectors of strength, Delta inclination - Delta declination, meanwhile we also use a triaxial fluxgate instrument of the traditional instrument for geomagnetic vector filed measurement. The advantages of this method are be calibrated by each other and get good performances with automatic operation, good stability and high resolution. Firstly, a brief description of the instrument measurement principles and the key technologies are given. The instrument used a spherical coil system with 34 coils to product the homogeneous volume inside the coils which is large enough to accommodate the sensor of Overhauser total field sensor; the rest of the footlocker-sized ocean-bottom vector magnetometer consists of equipment to run the sensors and records its data (batteries and a data logger), weight to sink it to the sea floor, a remote-controlled acoustic release and flotation to bring the instrument back to the surface. Finally, the accuracy of the instrument was tested in the Geomagnetic station, and the measurement accuracies of total strength and components were better than 0.2nT and 1nT respectively. The figure 1 shows the development instrument structure. it includes six thick glass spheres which protect the sensor, data logger and batteries from the pressures of the deep sea, meanwhile they also provide recycling positive buoyancy; To cushion the glass, the spheres then go inside yellow plastic "hardhats". The triaxial fluxgate is inside No.1 glass spheres, data logger and batteries are inside No.2 glass spheres, the new vector sensor is inside No.3 glass spheres, acoustic communication unit is inside No.4 glass spheres, No.5 and No.6 glass spheres are empty which only provide recycling positive buoyancy. The figure 2 shows the development instrument Physical photo.
NASA Technical Reports Server (NTRS)
Murray, Jonathan
1992-01-01
Control gains computed via matrix Riccati equation. Software-based system controlling aim of gimbaled rocket motor on spacecraft adaptive and optimal in sense it adjusts control gains in response to feedback, according to optimizing algorithm based on cost function. Underlying control concept also applicable, with modifications, to thrust-vector control on vertical-takeoff-and-landing airplanes, control of orientations of scientific instruments, and robotic control systems.
Ultrasonic Dynamic Vector Stress Sensor
NASA Technical Reports Server (NTRS)
Heyman, Joseph S.; Froggatt, Mark
1992-01-01
Stress inferred from measurements in specimens rather than in bonded gauges. Ultrasonic dynamic vector stress sensor (UDVSS) measures changes in dynamic directional stress occurring in material or structure at location touched by device when material or structure put under cyclic load. Includes phase-locked loop, synchronous amplifier, and contact probe. Useful among manufacturers of aerospace and automotive structures for stress testing and evaluation of designs.
Visualizing vector field topology in fluid flows
NASA Technical Reports Server (NTRS)
Helman, James L.; Hesselink, Lambertus
1991-01-01
Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.
Transmission parameters of vector-borne infections.
Desenclos, J-C
2011-11-01
Vector-borne infections are those for which the agent (virus, bacteria, or parasite) is transmitted from an infected host (animal or human) to another by a hematophagous arthropod (mosquito, tick, lice, and flea). Two parameters quantify the dynamics of a vector-borne infection: (1) the basic reproductive number (R(0)) that is the mean number of secondary infections transmitted from an infectious host by the bite of the vector and (2) the generation interval that explores the speed of occurrence of secondary cases transmitted by the vector from an infectious case. In a population in which some individuals are immune, the parameter of interest is the net reproduction number (R) function of R(0) and the proportion of those immune. For vector-borne infectious agents, R(0) is determined by the number of vectors in contact with a given individual (m), the number of a given vector bites/day on individuals (a), the daily survival rate of the vector (p), the duration of the pathogenic agent's development cycle in the vector (n), the proportion of infected vectors that are really infectious (vector competence) (b), the probability of agent transmission from a viremic individual to the vector for one bite (c) and the host's infectiousness clearance rate (r) with R(0)=(m. a(2). p(n)/-lnp). b. c/r. These parameters are related to geographic and climatic conditions and cannot, therefore, be extrapolated from one situation to another.
MISR Level 3 Cloud Motion Vector
Atmospheric Science Data Center
2013-07-10
MISR Level 3 Cloud Motion Vector Level 3 Wednesday, November 7, 2012 ... A new version, F02_0002, of the MISR L3 CMV (Cloud Motion Vector) data product is now available. This new release provides finer ... coverage. These enhancements are the result of reorganizing motion vector information present in the recent Level 2 Cloud product as ...
Gaussian statistics for palaeomagnetic vectors
Love, J.J.; Constable, C.G.
2003-01-01
With the aim of treating the statistics of palaeomagnetic directions and intensities jointly and consistently, we represent the mean and the variance of palaeomagnetic vectors, at a particular site and of a particular polarity, by a probability density function in a Cartesian three-space of orthogonal magnetic-field components consisting of a single (unimoda) non-zero mean, spherically-symmetrical (isotropic) Gaussian function. For palaeomagnetic data of mixed polarities, we consider a bimodal distribution consisting of a pair of such symmetrical Gaussian functions, with equal, but opposite, means and equal variances. For both the Gaussian and bi-Gaussian distributions, and in the spherical three-space of intensity, inclination, and declination, we obtain analytical expressions for the marginal density functions, the cumulative distributions, and the expected values and variances for each spherical coordinate (including the angle with respect to the axis of symmetry of the distributions). The mathematical expressions for the intensity and off-axis angle are closed-form and especially manageable, with the intensity distribution being Rayleigh-Rician. In the limit of small relative vectorial dispersion, the Gaussian (bi-Gaussian) directional distribution approaches a Fisher (Bingham) distribution and the intensity distribution approaches a normal distribution. In the opposite limit of large relative vectorial dispersion, the directional distributions approach a spherically-uniform distribution and the intensity distribution approaches a Maxwell distribution. We quantify biases in estimating the properties of the vector field resulting from the use of simple arithmetic averages, such as estimates of the intensity or the inclination of the mean vector, or the variances of these quantities. With the statistical framework developed here and using the maximum-likelihood method, which gives unbiased estimates in the limit of large data numbers, we demonstrate how to
Vectors derived from simian immunodeficiency virus (SIV).
Nègre, Didier; Cosset, François-Loïc
2002-11-01
In contrast to other retroviruses, lentiviruses have the unique property of infecting non-proliferating cells. Thus vectors derived from lentiviruses are promising tools for in vivo gene delivery applications. Vectors derived from human primate and non-primate lentiviruses have recently been described and, unlike retroviral vectors derived from murine leukemia viruses, lead to stable integration of the transgene into quiescent cells in various organs. Despite all the safety safeguards that have been progressively introduced in lentiviral vectors, the clinical acceptance of vectors derived from pathogenic lentiviruses is subject to debate. It is therefore essential to design vectors derived from a wide range of lentivirus types and to comparatively examine their properties in terms of transduction efficiency and bio-safety. Here, we review the properties of lentiviral vectors derived from simian immunodeficiency virus (SIV).
Vaccine Design: Replication-Defective Adenovirus Vectors.
Zhou, Xiangyang; Xiang, Zhiquan; Ertl, Hildegund C J
2016-01-01
Replication-defective adenovirus (Ad) vectors were initially developed for gene transfer for correction of genetic diseases. Although Ad vectors achieved high levels of transgene product expression in a variety of target cells, expression of therapeutic proteins was found to be transient as vigorous T cell responses directed to components of the vector as well as the transgene product rapidly eliminate Ad vector-transduced cells. This opened the use of Ad vectors as vaccine carriers and by now a multitude of preclinical as well as clinical studies has shown that Ad vectors induce very potent and sustained transgene product-specific T and B cell responses. This chapter provides guidance on developing E1-deleted Ad vectors based on available viral molecular clones. Specifically, it describes methods for cloning, viral rescue and purification as well as quality control studies.
Multiscale vector fields for image pattern recognition
NASA Technical Reports Server (NTRS)
Low, Kah-Chan; Coggins, James M.
1990-01-01
A uniform processing framework for low-level vision computing in which a bank of spatial filters maps the image intensity structure at each pixel into an abstract feature space is proposed. Some properties of the filters and the feature space are described. Local orientation is measured by a vector sum in the feature space as follows: each filter's preferred orientation along with the strength of the filter's output determine the orientation and the length of a vector in the feature space; the vectors for all filters are summed to yield a resultant vector for a particular pixel and scale. The orientation of the resultant vector indicates the local orientation, and the magnitude of the vector indicates the strength of the local orientation preference. Limitations of the vector sum method are discussed. Investigations show that the processing framework provides a useful, redundant representation of image structure across orientation and scale.
Vector meson electroproduction in QCD
NASA Astrophysics Data System (ADS)
Lu, Juan; Cai, Xian-Hao; Zhou, Li-Juan
2012-08-01
Based on the generalized QCD vector meson dominance model, we study the electroproduction of a vector meson off a proton in the QCD inspired eikonalized model. Numerical calculations for the total cross section σtot and differential cross section dσ/dt are performed for ρ, ω and varphi meson electroproduction in this paper. Since gluons interact among themselves (self-interaction), two gluons can form a glueball with quantum numbers IG, JPC = 0+,2++, decay width Γt ≈ 100 MeV, and mass of mG = 2.23 GeV. The three gluons can form a three-gluon colorless bound state with charge conjugation quantum number C = -1, called the Odderon. The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the virtual photon) and the proton target (a three-quark system) are the tensor glueball and the Odderon. Our calculated results in the tensor glueball and Odderon exchange model fit to the existing data successfully, which evidently shows that our present QCD mechanism is a good description of meson electroproduction off a proton. It should be emphasized that our mechanism is different from the theoretical framework of Block et al. We also believe that the present study and its success are important for the investigation of other vector meson electro- and photoproduction at high energies, as well as for searching for new particles such as tensor glueballs and Odderons, which have been predicted by QCD and the color glass condensate model (CGC). Therefore, in return, it can test the validity of QCD and the CGC model.
Properties of Vector Preisach Models
NASA Technical Reports Server (NTRS)
Kahler, Gary R.; Patel, Umesh D.; Torre, Edward Della
2004-01-01
This paper discusses rotational anisotropy and rotational accommodation of magnetic particle tape. These effects have a performance impact during the reading and writing of the recording process. We introduce the reduced vector model as the basis for the computations. Rotational magnetization models must accurately compute the anisotropic characteristics of ellipsoidally magnetizable media. An ellipticity factor is derived for these media that computes the two-dimensional magnetization trajectory for all applied fields. An orientation correction must be applied to the computed rotational magnetization. For isotropic materials, an orientation correction has been developed and presented. For anisotropic materials, an orientation correction is introduced.
Vector quantization for volume rendering
NASA Technical Reports Server (NTRS)
Ning, Paul; Hesselink, Lambertus
1992-01-01
Volume rendering techniques typically process volumetric data in raw, uncompressed form. As algorithmic and architectural advances improve rendering speeds, however, larger data sets will be evaluated requiring consideration of data storage and transmission issues. In this paper, we analyze the data compression requirements for volume rendering applications and present a solution based on vector quantization. The proposed system compresses volumetric data and then renders images directly from the new data format. Tests on a fluid flow data set demonstrate that good image quality may be achieved at a compression ratio of 17:1 with only a 5 percent cost in additional rendering time.
Jet vectoring through nozzle asymmetry
NASA Astrophysics Data System (ADS)
Roh, Chris; Rosakis, Alexandros; Gharib, Morteza
2015-11-01
Previously, we explored the functionality of a tri-leaflet anal valve of a dragonfly larva. We saw that the dragonfly larva is capable of controlling the three leaflets independently to asymmetrically open the nozzle. Such control resulted in vectoring of the jet in various directions. To further understand the effect of asymmetric nozzle orifice, we tested jet flow through circular asymmetric nozzles. We report the relationship between nozzle asymmetry and redirecting of the jet at various Reynolds numbers. This material is based upon work supported by the National Science Foundation under Grant No. CBET-1511414; additional support by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469.
Nonviral Vectors for Gene Delivery
NASA Astrophysics Data System (ADS)
Baoum, Abdulgader Ahmed
2011-12-01
The development of nonviral vectors for safe and efficient gene delivery has been gaining considerable attention recently. An ideal nonviral vector must protect the gene against degradation by nuclease in the extracellular matrix, internalize the plasma membrane, escape from the endosomal compartment, unpackage the gene at some point and have no detrimental effects. In comparison to viruses, nonviral vectors are relatively easy to synthesize, less immunogenic, low in cost, and have no limitation in the size of a gene that can be delivered. Significant progress has been made in the basic science and applications of various nonviral gene delivery vectors; however, the majority of nonviral approaches are still inefficient and often toxic. To this end, two nonviral gene delivery systems using either biodegradable poly(D,L-lactide- co-glycolide) (PLG) nanoparticles or cell penetrating peptide (CPP) complexes have been designed and studied using A549 human lung epithelial cells. PLG nanoparticles were optimized for gene delivery by varying particle surface chemistry using different coating materials that adsorb to the particle surface during formation. A variety of cationic coating materials were studied and compared to more conventional surfactants used for PLG nanoparticle fabrication. Nanoparticles (˜200 nm) efficiently encapsulated plasmids encoding for luciferase (80-90%) and slowly released the same for two weeks. After a delay, moderate levels of gene expression appeared at day 5 for certain positively charged PLG particles and gene expression was maintained for at least two weeks. In contrast, gene expression mediated by polyethyleneimine (PEI) ended at day 5. PLG particles were also significantly less cytotoxic than PEI suggesting the use of these vehicles for localized, sustained gene delivery to the pulmonary epithelium. On the other hand, a more simple method to synthesize 50-200 nm complexes capable of high transfection efficiency or high gene knockdown was
Conformal vectors and stellar models
NASA Astrophysics Data System (ADS)
Manjonjo, A. M.; Maharaj, S. D.; Moopanar, S.
2017-02-01
The relationship between conformal symmetries and relativistic spheres in astrophysics is studied. We use the nonvanishing components of the Weyl tensor to classify the conformal symmetries in static spherical spacetimes. It is possible to find an explicit connection between the two gravitational potentials for both conformally flat and nonconformally flat cases. We show that the conformal Killing vector admits time dependence in terms of quadratic, trigonometric and hyperbolic functions. The Einstein and Einstein-Maxwell field equations can be written in terms of a single potential, any choice of which leads to an exact solution. Previous results of conformally invariant static spheres are contained in our treatment.
Vector-Tensor and Vector-Vector Decay AmplitudeAnalysis of B0 to phi K*0
Aubert, B.
2006-10-31
We perform an amplitude analysis of the decays B{sup 0} {yields} {phi}K*{sub 2}(1430){sup 0}, {phi}K*(892){sup 0}, and {phi}(K{pi}){sub S-wave}{sup 0} with a sample of about 384 million B{bar B} pairs recorded with the BABAR detector. The fractions of longitudinal polarization f{sub L} of the vector-tensor and vector-vector decay modes are measured to be 0.853{sub -0.069}{sup +0.061} {+-} 0.036 and 0.506 {+-} 0.040 {+-} 0.015, respectively. Overall, twelve parameters are measured for the vector-vector decay and seven parameters for the vector-tensor decay, including the branching fractions and parameters sensitive to CP-violation.
Vector-tensor and vector-vector decay amplitude analysis of B0-->phiK*0.
Aubert, B; Bona, M; Boutigny, D; Couderc, F; Karyotakis, Y; Lees, J P; Poireau, V; Tisserand, V; Zghiche, A; Grauges, E; Palano, A; Chen, J C; Qi, N D; Rong, G; Wang, P; Zhu, Y S; Eigen, G; Ofte, I; Stugu, B; Abrams, G S; Battaglia, M; Brown, D N; Button-Shafer, J; Cahn, R N; Charles, E; Gill, M S; Groysman, Y; Jacobsen, R G; Kadyk, J A; Kerth, L T; Kolomensky, Yu G; Kukartsev, G; Pegna, D Lopes; Lynch, G; Mir, L M; Orimoto, T J; Pripstein, M; Roe, N A; Ronan, M T; Wenzel, W A; Sanchez, P del Amo; Barrett, M; Ford, K E; Harrison, T J; Hart, A J; Hawkes, C M; Watson, A T; Held, T; Koch, H; Lewandowski, B; Pelizaeus, M; Peters, K; Schroeder, T; Steinke, M; Boyd, J T; Burke, J P; Cottingham, W N; Walker, D; Asgeirsson, D J; Cuhadar-Donszelmann, T; Fulsom, B G; Hearty, C; Knecht, N S; Mattison, T S; McKenna, J A; Khan, A; Kyberd, P; Saleem, M; Sherwood, D J; Teodorescu, L; Blinov, V E; Bukin, A D; Druzhinin, V P; Golubev, V B; Onuchin, A P; Serednyakov, S I; Skovpen, Yu I; Solodov, E P; Todyshev, K Yu; Best, D S; Bondioli, M; Bruinsma, M; Chao, M; Curry, S; Eschrich, I; Kirkby, D; Lankford, A J; Lund, P; Mandelkern, M; Roethel, W; Stoker, D P; Abachi, S; Buchanan, C; Foulkes, S D; Gary, J W; Long, O; Shen, B C; Wang, K; Zhang, L; Hadavand, H K; Hill, E J; Paar, H P; Rahatlou, S; Sharma, V; Berryhill, J W; Campagnari, C; Cunha, A; Dahmes, B; Hong, T M; Kovalskyi, D; Richman, J D; Beck, T W; Eisner, A M; Flacco, C J; Heusch, C A; Kroseberg, J; Lockman, W S; Nesom, G; Schalk, T; Schumm, B A; Seiden, A; Spradlin, P; Williams, D C; Wilson, M G; Albert, J; Chen, E; Cheng, C H; Dvoretskii, A; Fang, F; Hitlin, D G; Narsky, I; Piatenko, T; Porter, F C; Mancinelli, G; Meadows, B T; Mishra, K; Sokoloff, M D; Blanc, F; Bloom, P C; Chen, S; Ford, W T; Hirschauer, J F; Kreisel, A; Nagel, M; Nauenberg, U; Olivas, A; Ruddick, W O; Smith, J G; Ulmer, K A; Wagner, S R; Zhang, J; Chen, A; Eckhart, E A; Soffer, A; Toki, W H; Wilson, R J; Winklmeier, F; Zeng, Q; Altenburg, D D; Feltresi, E; Hauke, A; Jasper, H; Merkel, J; Petzold, A; Spaan, B; Brandt, T; Klose, V; Lacker, H M; Mader, W F; Nogowski, R; Schubert, J; Schubert, K R; Schwierz, R; Sundermann, J E; Volk, A; Bernard, D; Bonneaud, G R; Latour, E; Thiebaux, Ch; Verderi, M; Clark, P J; Gradl, W; Muheim, F; Playfer, S; Robertson, A I; Xie, Y; Andreotti, M; Bettoni, D; Bozzi, C; Calabrese, R; Cibinetto, G; Luppi, E; Negrini, M; Petrella, A; Piemontese, L; Prencipe, E; Anulli, F; Baldini-Ferroli, R; Calcaterra, A; de Sangro, R; Finocchiaro, G; Pacetti, S; Patteri, P; Peruzzi, I M; Piccolo, M; Rama, M; Zallo, A; Buzzo, A; Contri, R; Vetere, M Lo; Macri, M M; Monge, M R; Passaggio, S; Patrignani, C; Robutti, E; Santroni, A; Tosi, S; Brandenburg, G; Chaisanguanthum, K S; Lee, C L; Morii, M; Wu, J; Dubitzky, R S; Marks, J; Schenk, S; Uwer, U; Bard, D J; Bhimji, W; Bowerman, D A; Dauncey, P D; Egede, U; Flack, R L; Nash, J A; Nikolich, M B; Vazquez, W Panduro; Behera, P K; Chai, X; Charles, M J; Mallik, U; Meyer, N T; Ziegler, V; Cochran, J; Crawley, H B; Dong, L; Eyges, V; Meyer, W T; Prell, S; Rosenberg, E I; Rubin, A E; Gao, Y; Gritsan, A V; Guo, Z J; Denig, A G; Fritsch, M; Schott, G; Arnaud, N; Davier, M; Grosdidier, G; Höcker, A; Lepeltier, V; Diberder, F Le; Lutz, A M; Oyanguren, A; Pruvot, S; Rodier, S; Roudeau, P; Schune, M H; Serrano, J; Stocchi, A; Wang, W F; Wormser, G; Lange, D J; Wright, D M; Chavez, C A; Forster, I J; Fry, J R; Gabathuler, E; Gamet, R; George, K A; Hutchcroft, D E; Payne, D J; Schofield, K C; Touramanis, C; Bevan, A J; Clarke, C K; Lodovico, F Di; Menges, W; Sacco, R; Cowan, G; Flaecher, H U; Hopkins, D A; Jackson, P S; McMahon, T R; Salvatore, F; Wren, A C; Brown, D N; Davis, C L; Allison, J; Barlow, N R; Barlow, R J; Chia, Y M; Edgar, C L; Lafferty, G D; Naisbit, M T; Williams, J C; Yi, J I; Chen, C; Hulsbergen, W D; Jawahery, A; Lae, C K; Roberts, D A; Simi, G; Blaylock, G; Dallapiccola, C; Hertzbach, S S; Li, X; Moore, T B; Saremi, S; Staengle, H; Cowan, R; Sciolla, G; Sekula, S J; Spitznagel, M; Taylor, F; Yamamoto, R K; Kim, H; McLachlin, S E; Patel, P M; Robertson, S H; Lazzaro, A; Lombardo, V; Palombo, F; Bauer, J M; Cremaldi, L; Eschenburg, V; Godang, R; Kroeger, R; Sanders, D A; Summers, D J; Zhao, H W; Brunet, S; Côté, D; Simard, M; Taras, P; Viaud, F B; Nicholson, H; Cavallo, N; Nardo, G De; Fabozzi, F; Gatto, C; Lista, L; Monorchio, D; Paolucci, P; Piccolo, D; Sciacca, C; Baak, M A; Raven, G; Snoek, H L; Jessop, C P; Losecco, J M; Benelli, G; Corwin, L A; Gan, K K; Honscheid, K; Hufnagel, D; Jackson, P D; Kagan, H; Kass, R; Rahimi, A M; Regensburger, J J; Ter-Antonyan, R; Wong, Q K; Blount, N L; Brau, J; Frey, R; Igonkina, O; Kolb, J A; Lu, M; Potter, C T; Rahmat, R; Sinev, N B; Strom, D; Strube, J; Torrence, E; Gaz, A; Margoni, M; Morandin, M; Pompili, A; Posocco, M; Rotondo, M; Simonetto, F; Stroili, R; Voci, C; Benayoun, M; Briand, H; Chauveau, J; David, P; Buono, L Del; de la Vaissière, Ch; Hamon, O; Hartfiel, B L; Leruste, Ph; Malclès, J; Ocariz, J; Roos, L; Therin, G; Gladney, L; Biasini, M; Covarelli, R; Angelini, C; Batignani, G; Bettarini, S; Bucci, F; Calderini, G; Carpinelli, M; Cenci, R; Forti, F; Giorgi, M A; Lusiani, A; Marchiori, G; Mazur, M A; Morganti, M; Neri, N; Paoloni, E; Rizzo, G; Walsh, J J; Haire, M; Judd, D; Wagoner, D E; Biesiada, J; Danielson, N; Elmer, P; Lau, Y P; Lu, C; Olsen, J; Smith, A J S; Telnov, A V; Bellini, F; Cavoto, G; D'Orazio, A; del Re, D; Marco, E Di; Faccini, R; Ferrarotto, F; Ferroni, F; Gaspero, M; Gioi, L Li; Mazzoni, M A; Morganti, S; Piredda, G; Polci, F; Tehrani, F Safai; Voena, C; Ebert, M; Schröder, H; Waldi, R; Adye, T; Franek, B; Olaiya, E O; Ricciardi, S; Wilson, F F; Aleksan, R; Emery, S; Gaidot, A; Ganzhur, S F; de Monchenault, G Hamel; Kozanecki, W; Legendre, M; Vasseur, G; Yèche, Ch; Zito, M; Chen, X R; Liu, H; Park, W; Purohit, M V; Wilson, J R; Allen, M T; Aston, D; Bartoldus, R; Bechtle, P; Berger, N; Claus, R; Coleman, J P; Convery, M R; Dingfelder, J C; Dorfan, J; Dubois-Felsmann, G P; Dujmic, D; Dunwoodie, W; Field, R C; Glanzman, T; Gowdy, S J; Graham, M T; Grenier, P; Halyo, V; Hast, C; Hryn'ova, T; Innes, W R; Kelsey, M H; Kim, P; Leith, D W G S; Li, S; Luitz, S; Luth, V; Lynch, H L; Macfarlane, D B; Marsiske, H; Messner, R; Muller, D R; O'Grady, C P; Ozcan, V E; Perazzo, A; Perl, M; Pulliam, T; Ratcliff, B N; Roodman, A; Salnikov, A A; Schindler, R H; Schwiening, J; Snyder, A; Stelzer, J; Su, D; Sullivan, M K; Suzuki, K; Swain, S K; Thompson, J M; Va'vra, J; van Bakel, N; Wagner, A P; Weaver, M; Weinstein, A J R; Wisniewski, W J; Wittgen, M; Wright, D H; Wulsin, H W; Yarritu, A K; Yi, K; Young, C C; Burchat, P R; Edwards, A J; Majewski, S A; Petersen, B A; Wilden, L; Ahmed, S; Alam, M S; Bula, R; Ernst, J A; Jain, V; Pan, B; Saeed, M A; Wappler, F R; Zain, S B; Bugg, W; Krishnamurthy, M; Spanier, S M; Eckmann, R; Ritchie, J L; Satpathy, A; Schilling, C J; Schwitters, R F; Izen, J M; Lou, X C; Ye, S; Bianchi, F; Gallo, F; Gamba, D; Bomben, M; Bosisio, L; Cartaro, C; Cossutti, F; Ricca, G Della; Dittongo, S; Lanceri, L; Vitale, L; Azzolini, V; Lopez-March, N; Martinez-Vidal, F; Banerjee, Sw; Bhuyan, B; Brown, C M; Fortin, D; Hamano, K; Kowalewski, R; Nugent, I M; Roney, J M; Sobie, R J; Back, J J; Harrison, P F; Latham, T E; Mohanty, G B; Pappagallo, M; Band, H R; Chen, X; Cheng, B; Dasu, S; Datta, M; Flood, K T; Hollar, J J; Kutter, P E; Mellado, B; Mihalyi, A; Pan, Y; Pierini, M; Prepost, R; Wu, S L; Yu, Z; Neal, H
2007-02-02
We perform an amplitude analysis of the decays B(0)-->phiK*(2)(1430)(0), phiK*(892)(0), and phi(Kpi)(0)(S-wave) with a sample of about 384x10(6) BB[over ] pairs recorded with the BABAR detector. The fractions of longitudinal polarization f(L) of the vector-tensor and vector-vector decay modes are measured to be 0.853(-0.069+0.061)+/-0.036 and 0.506+/-0.040+/-0.015, respectively. Overall, twelve parameters are measured for the vector-vector decay and seven parameters for the vector-tensor decay, including the branching fractions and parameters sensitive to CP violation.
Viral Vectors: The Road to Reducing Genotoxicity.
David, Rhiannon M; Doherty, Ann T
2017-02-01
Viral vector use in gene therapy has highlighted several safety concerns, including genotoxic events. Generally, vector-mediated genotoxicity results from upregulation of cellular proto-oncogenes via promoter insertion, promoter activation, or gene transcript truncation, with enhancer-mediated activation of nearby genes the primary mechanism reported in gene therapy trials. Vector-mediated genotoxicity can be influenced by virus type, integration target site, and target cell type; different vectors have distinct integration profiles which are cell-specific. Non-viral factors, including patient age, disease, and dose can also influence genotoxic potential, thus the choice of test models and clinical trial populations is important to ensure they are indicative of efficacy and safety. Efforts have been made to develop viral vectors with less risk of insertional mutagenesis, including self-inactivating (SIN) vectors, enhancer-blocking insulators, and microRNA targeting of vectors, although insertional mutagenesis is not completely abrogated. Here we provide an overview of the current understanding of viral vector-mediated genotoxicity risk from factors contributing to viral vector-mediated genotoxicity to efforts made to reduce genotoxicity, and testing strategies required to adequately assess the risk of insertional mutagenesis. It is clear that there is not a 'one size fits all' approach to vector modification for reducing genotoxicity, and addressing these challenges will be a key step in the development of therapies such as CRISPR-Cas9 and delivery of future gene-editing technologies.
Viral vectors for vascular gene therapy
Fischer, Lukas; Preis, Meir; Weisz, Anat; Koren, Belly; Lewis, Basil S; Flugelman, Moshe Y
2002-01-01
Vascular gene therapy is the focus of multiple experimental and clinical research efforts. While several genes with therapeutic potential have been identified, the best method of gene delivery is unknown. Viral vectors have the capacity to transfer genes at high efficiency rates. Several viral-based vectors have been used in experimental vascular gene therapy for in vivo and ex vivo gene transfer. Adenoviral-based vectors are being used for the induction of angiogenesis in phase 1 and 2 clinical trials. In the present review, the characteristics of the ‘ideal’ viral vector are discussed and the major types of viral vectors used in vascular gene transfer are reviewed. Basic knowledge of the use of viral vectors for direct in vivo gene transfer (adenoviral-based vectors, etc) and for ex vivo gene transfer (retroviral-based vectors) is provided. New developments in the field of viral vectorology, such as pseudotyping of retroviral vectors and targeting of other viral vectors to a specific cell type, will enhance the more rapid transition of vascular gene therapy from the experimental arena to the clinical setting. PMID:19649233
Dengue Vectors and their Spatial Distribution
Higa, Yukiko
2011-01-01
The distribution of dengue vectors, Ae. aegypti and Ae. albopictus, is affected by climatic factors. In addition, since their life cycles are well adapted to the human environment, environmental changes resulting from human activity such as urbanization exert a great impact on vector distribution. The different responses of Ae. aegypti and Ae albopictus to various environments result in a difference in spatial distribution along north-south and urban-rural gradients, and between the indoors and outdoors. In the north-south gradient, climate associated with survival is an important factor in spatial distribution. In the urban-rural gradient, different distribution reflects a difference in adult niches and is modified by geographic and human factors. The direct response of the two species to the environment around houses is related to different spatial distribution indoors and outdoors. Dengue viruses circulate mainly between human and vector mosquitoes, and the vector presence is a limiting factor of transmission. Therefore, spatial distribution of dengue vectors is a significant concern in the epidemiology of the disease. Current technologies such as GIS, satellite imagery and statistical models allow researchers to predict the spatial distribution of vectors in the changing environment. Although it is difficult to confirm the actual effect of environmental and climate changes on vector abundance and vector-borne diseases, environmental changes caused by humans and human behavioral changes due to climate change can be expected to exert an impact on dengue vectors. Longitudinal monitoring of dengue vectors and viruses is therefore necessary. PMID:22500133
Therapeutic and prophylactic applications of alphavirus vectors.
Atkins, Gregory J; Fleeton, Marina N; Sheahan, Brian J
2008-11-11
Alphavirus vectors are high-level, transient expression vectors for therapeutic and prophylactic use. These positive-stranded RNA vectors, derived from Semliki Forest virus, Sindbis virus and Venezuelan equine encephalitis virus, multiply and are expressed in the cytoplasm of most vertebrate cells, including human cells. Part of the genome encoding the structural protein genes, which is amplified during a normal infection, is replaced by a transgene. Three types of vector have been developed: virus-like particles, layered DNA-RNA vectors and replication-competent vectors. Virus-like particles contain replicon RNA that is defective since it contains a cloned gene in place of the structural protein genes, and thus are able to undergo only one cycle of expression. They are produced by transfection of vector RNA, and helper RNAs encoding the structural proteins. Layered DNA-RNA vectors express the Semliki Forest virus replicon from a cDNA copy via a cytomegalovirus promoter. Replication-competent vectors contain a transgene in addition to the structural protein genes. Alphavirus vectors are used for three main applications: vaccine construction, therapy of central nervous system disease, and cancer therapy.
Volumetric Acoustic Vector Intensity Probe
NASA Technical Reports Server (NTRS)
Klos, Jacob
2006-01-01
A new measurement tool capable of imaging the acoustic intensity vector throughout a large volume is discussed. This tool consists of an array of fifty microphones that form a spherical surface of radius 0.2m. A simultaneous measurement of the pressure field across all the microphones provides time-domain near-field holograms. Near-field acoustical holography is used to convert the measured pressure into a volumetric vector intensity field as a function of frequency on a grid of points ranging from the center of the spherical surface to a radius of 0.4m. The volumetric intensity is displayed on three-dimensional plots that are used to locate noise sources outside the volume. There is no restriction on the type of noise source that can be studied. The sphere is mobile and can be moved from location to location to hunt for unidentified noise sources. An experiment inside a Boeing 757 aircraft in flight successfully tested the ability of the array to locate low-noise-excited sources on the fuselage. Reference transducers located on suspected noise source locations can also be used to increase the ability of this device to separate and identify multiple noise sources at a given frequency by using the theory of partial field decomposition. The frequency range of operation is 0 to 1400Hz. This device is ideal for the study of noise sources in commercial and military transportation vehicles in air, on land and underwater.
[Individual protection against insect vectors].
Carnevale, P; Mouchet, J
1997-01-01
Many diseases for which no vaccine is available are transmitted by insect and arthropod vectors, the main exceptions being yellow fever and Japanese encephalitis B. Treatment is less and less effective due to the development of chemoresistance to therapeutic and prophylactic drugs as is well-illustrated by malaria. One of the best methods of preventing these diseases is personal protection against insect bites. Personal protection measures can be divided into three categories which can be used separately or in combination : application of repellents to the skin, wearing clothes impregnated with insecticides, and use of bed nets and other barriers impregnated with insecticides. The choice of method depends on the type of insect vector involved. For insects that are active during the day or at dusk, application of repellents to the skin gives good short-term protection and wearing impregnated clothes is useful. Bed nets that have been properly impregnated with pyrethroids are highly effective for night-time protection. Since personal protection methods are not 100% effective, they must be used in association with chemoprophylaxis according to medical guidelines. Medical advice should be sought if fever should occur especially after returning from a trip in the tropics.
Genetics of Mosquito Vector Competence
Beerntsen, Brenda T.; James, Anthony A.; Christensen, Bruce M.
2000-01-01
Mosquito-borne diseases are responsible for significant human morbidity and mortality throughout the world. Efforts to control mosquito-borne diseases have been impeded, in part, by the development of drug-resistant parasites, insecticide-resistant mosquitoes, and environmental concerns over the application of insecticides. Therefore, there is a need to develop novel disease control strategies that can complement or replace existing control methods. One such strategy is to generate pathogen-resistant mosquitoes from those that are susceptible. To this end, efforts have focused on isolating and characterizing genes that influence mosquito vector competence. It has been known for over 70 years that there is a genetic basis for the susceptibility of mosquitoes to parasites, but until the advent of powerful molecular biological tools and protocols, it was difficult to assess the interactions of pathogens with their host tissues within the mosquito at a molecular level. Moreover, it has been only recently that the molecular mechanisms responsible for pathogen destruction, such as melanotic encapsulation and immune peptide production, have been investigated. The molecular characterization of genes that influence vector competence is becoming routine, and with the development of the Sindbis virus transducing system, potential antipathogen genes now can be introduced into the mosquito and their effect on parasite development can be assessed in vivo. With the recent successes in the field of mosquito germ line transformation, it seems likely that the generation of a pathogen-resistant mosquito population from a susceptible population soon will become a reality. PMID:10704476
Vector-Resonance-Multimode Instability
NASA Astrophysics Data System (ADS)
Sergeyev, S. V.; Kbashi, H.; Tarasov, N.; Loiko, Yu.; Kolpakov, S. A.
2017-01-01
The modulation and multimode instabilities are the main mechanisms which drive spontaneous spatial and temporal pattern formation in a vast number of nonlinear systems ranging from biology to laser physics. Using an Er-doped fiber laser as a test bed, here for the first time we demonstrate both experimentally and theoretically a new type of a low-threshold vector-resonance-multimode instability which inherits features of multimode and modulation instabilities. The same as for the multimode instability, a large number of longitudinal modes can be excited without mode synchronization. To enable modulation instability, we modulate the state of polarization of the lasing signal with the period of the beat length by an adjustment of the in-cavity birefringence and the state of polarization of the pump wave. As a result, we show the regime's tunability from complex oscillatory to periodic with longitudinal mode synchronization in the case of resonance matching between the beat and cavity lengths. Apart from the interest in laser physics for unlocking the tunability and stability of dynamic regimes, the proposed mechanism of the vector-resonance-multimode instability can be of fundamental interest for the nonlinear dynamics of various distributed systems.
New protocol for lentiviral vector mass production.
Segura, María Mercedes; Garnier, Alain; Durocher, Yves; Ansorge, Sven; Kamen, Amine
2010-01-01
Multiplasmid transient transfection is the most widely used technique for the generation of lentiviral vectors. However, traditional transient transfection protocols using 293 T adherent cells and calcium phosphate/DNA co-precipitation followed by ultracentrifugation are tedious, time-consuming, and difficult to scale up. This chapter describes a streamlined protocol for the fast mass production of lentiviral vectors and their purification by affinity chromatography. Lentiviral particles are generated by transient transfection of suspension growing HEK 293 cells in serum-free medium using polyethylenimine (PEI) as transfection reagent. Lentiviral vector production is carried out in Erlenmeyer flasks agitated on orbital shakers requiring minimum supplementary laboratory equipment. Alternatively, the method can be easily scaled up to generate larger volumes of vector stocks in bioreactors. Heparin affinity chromatography allows for selective concentration and purification of lentiviral particles in a singlestep directly from vector supernatants. The method is suitable for the production and purification of different vector pseudotypes.
Vector assembly of colloids on monolayer substrates
Jiang, Lingxiang; Yang, Shenyu; Tsang, Boyce; Tu, Mei; Granick, Steve
2017-01-01
The key to spontaneous and directed assembly is to encode the desired assembly information to building blocks in a programmable and efficient way. In computer graphics, raster graphics encodes images on a single-pixel level, conferring fine details at the expense of large file sizes, whereas vector graphics encrypts shape information into vectors that allow small file sizes and operational transformations. Here, we adapt this raster/vector concept to a 2D colloidal system and realize ‘vector assembly' by manipulating particles on a colloidal monolayer substrate with optical tweezers. In contrast to raster assembly that assigns optical tweezers to each particle, vector assembly requires a minimal number of optical tweezers that allow operations like chain elongation and shortening. This vector approach enables simple uniform particles to form a vast collection of colloidal arenes and colloidenes, the spontaneous dissociation of which is achieved with precision and stage-by-stage complexity by simply removing the optical tweezers. PMID:28594002
Vector assembly of colloids on monolayer substrates
NASA Astrophysics Data System (ADS)
Jiang, Lingxiang; Yang, Shenyu; Tsang, Boyce; Tu, Mei; Granick, Steve
2017-06-01
The key to spontaneous and directed assembly is to encode the desired assembly information to building blocks in a programmable and efficient way. In computer graphics, raster graphics encodes images on a single-pixel level, conferring fine details at the expense of large file sizes, whereas vector graphics encrypts shape information into vectors that allow small file sizes and operational transformations. Here, we adapt this raster/vector concept to a 2D colloidal system and realize `vector assembly' by manipulating particles on a colloidal monolayer substrate with optical tweezers. In contrast to raster assembly that assigns optical tweezers to each particle, vector assembly requires a minimal number of optical tweezers that allow operations like chain elongation and shortening. This vector approach enables simple uniform particles to form a vast collection of colloidal arenes and colloidenes, the spontaneous dissociation of which is achieved with precision and stage-by-stage complexity by simply removing the optical tweezers.
[Research progress on malaria vector control].
Zhu, Guo-Ding; Cao, Jun; Zhou, Hua-Yun; Gao, Qi
2013-06-01
Vector control plays a crucial role in the stages of malaria control and elimination. Currently, it mainly relies on the chemical control methods for adult mosquitoes in malaria endemic areas, however, it is undergoing the serious threat by insecticide resistance. In recent years, the transgenic technologies of malaria vectors have made a great progress in the laboratory. This paper reviews the challenges of the traditional methods and the rapid developed genetic modified technology in the application of vector control.
Observation of dipole-mode vector solitons
Krolikowski; Ostrovskaya; Weilnau; Geisser; McCarthy; Kivshar; Denz; Luther-Davies
2000-08-14
We report on the first experimental observation of a novel type of optical vector soliton, a dipole-mode soliton, recently predicted theoretically. We show that these vector solitons can be generated in a photorefractive medium employing two different processes: a phase imprinting, and a symmetry-breaking instability of a vortex-mode vector soliton. The experimental results display remarkable agreement with the theory, and confirm the robust nature of these radially asymmetric two-component solitary waves.
Pre-vector variational inequality
Lin, Lai-Jiu
1994-12-31
Let X be a Hausdorff topological vector space, (Y, D) be an ordered Hausdorff topological vector space ordered by convex cone D. Let L(X, Y) be the space of all bounded linear operator, E {improper_subset} X be a nonempty set, T : E {yields} L(X, Y), {eta} : E {times} E {yields} E be functions. For x, y {element_of} Y, we denote x {not_lt} y if y - x intD, where intD is the interior of D. We consider the following two problems: Find x {element_of} E such that < T(x), {eta}(y, x) > {not_lt} 0 for all y {element_of} E and find x {element_of} E, < T(x), {eta}(y, x) > {not_gt} 0 for all y {element_of} E and < T(x), {eta}(y, x) >{element_of} C{sub p}{sup w+} = {l_brace} {element_of} L(X, Y) {vert_bar}< l, {eta}(x, 0) >{not_lt} 0 for all x {element_of} E{r_brace} where < T(x), y > denotes linear operator T(x) at y, that is T(x), (y). We called Pre-VVIP the Pre-vector variational inequality problem and Pre-VCP complementary problem. If X = R{sup n}, Y = R, D = R{sub +} {eta}(y, x) = y - x, then our problem is the well-known variational inequality first studies by Hartman and Stampacchia. If Y = R, D = R{sub +}, {eta}(y, x) = y - x, our problem is the variational problem in infinite dimensional space. In this research, we impose different condition on T(x), {eta}, X, and < T(x), {eta}(y, x) > and investigate the existences theorem of these problems. As an application of one of our results, we establish the existence theorem of weak minimum of the problem. (P) V - min f(x) subject to x {element_of} E where f : X {yields} Y si a Frechet differentiable invex function.
Analysis of dissection algorithms for vector computers
NASA Technical Reports Server (NTRS)
George, A.; Poole, W. G., Jr.; Voigt, R. G.
1978-01-01
Recently two dissection algorithms (one-way and incomplete nested dissection) have been developed for solving the sparse positive definite linear systems arising from n by n grid problems. Concurrently, vector computers (such as the CDC STAR-100 and TI ASC) have been developed for large scientific applications. An analysis of the use of dissection algorithms on vector computers dictates that vectors of maximum length be utilized thereby implying little or no dissection; on the other hand, minimizing operation counts suggest that considerable dissection be performed. In this paper we discuss the resolution of this conflict by minimizing the total time required by vectorized versions of the two algorithms.
Building mosaics of therapeutic plasmid gene vectors.
Tolmachov, Oleg E
2011-12-01
Plasmids are circular or linear DNA molecules propagated extra-chromosomally in bacteria. Evolution shaped plasmids are inherently mosaic structures with individual functional units represented by distinct segments in the plasmid genome. The patchwork of plasmid genetic modules is a convenient template and a model for the generation of artificial plasmids used as vehicles for gene delivery into human cells. Plasmid gene vectors are an important tool in gene therapy and in basic biomedical research, where these vectors offer efficient transgene expression in many settings in vitro and in vivo. Plasmid vectors can be attached to nuclear directing ligands or transferred by electroporation as naked DNA to deliver the payload genes to the nuclei of the target cells. Transgene expression silencing by plasmid sequences of bacterial origin and immune stimulation by bacterial unmethylated CpG motifs can be avoided by the generation of plasmid-based minimized DNA vectors, such as minicircles. Systems of efficient site-specific integration into human chromosomes and stable episomal maintenance in human cells are being developed for further reduction of the chances for transgene silencing. The successful generation of plasmid vectors is governed by a number of vector design rules, some of which are common to all gene vectors, while others are specific to plasmid vectors. This review is focused both on the guiding principles and on the technical know-how of plasmid gene vector design.
Analysis of dissection algorithms for vector computers
NASA Technical Reports Server (NTRS)
George, A.; Poole, W. G., Jr.; Voigt, R. G.
1978-01-01
Recently two dissection algorithms (one-way and incomplete nested dissection) have been developed for solving the sparse positive definite linear systems arising from n by n grid problems. Concurrently, vector computers (such as the CDC STAR-100 and TI ASC) have been developed for large scientific applications. An analysis of the use of dissection algorithms on vector computers dictates that vectors of maximum length be utilized thereby implying little or no dissection; on the other hand, minimizing operation counts suggest that considerable dissection be performed. In this paper we discuss the resolution of this conflict by minimizing the total time required by vectorized versions of the two algorithms.
Surface-engineering of lentiviral vectors.
Verhoeyen, Els; Cosset, François-Loïc
2004-02-01
Vectors derived from retroviridae offer particularly flexible properties in gene transfer applications given the numerous possible associations of various viral surface glycoproteins (determining cell tropism) with different types of retroviral cores (determining genome replication and integration). Lentiviral vectors should be preferred gene delivery vehicles over vectors derived from onco-retroviruses such as murine leukemia viruses (MLVs) that cannot transduce non-proliferating target cells. Generating lentiviral vectors pseudotyped with different viral glycoproteins (GPs) may modulate the physicochemical properties of the vectors, their interaction with the host immune system and their host range. There are however important gene transfer restrictions to some non-proliferative tissues or cell types and recent studies have shown that progenitor hematopoietic stem cells in G(0), non-activated primary blood lymphocytes or monocytes were not transducible by lentiviral vectors. Moreover, lentiviral vectors that have the capacity to deliver transgenes into specific tissues are expected to be of great value for various gene transfer applications in vivo. Several innovative approaches have been explored to overcome such problems that have given rise to novel concepts in the field and have provided promising results in preliminary evaluations in vivo. Here we review the different approaches explored to upgrade lentiviral vectors, aiming at developing vectors suitable for in vivo gene delivery.
Production of high-capacity adenovirus vectors.
Kreppel, Florian
2014-01-01
High-capacity adenoviral vectors (HC-Ad), also known as "helper-dependent" (HD-Ad), "gutless", "gutted", or "third-generation" Ad vectors, are devoid of all viral coding sequences and have shown promising potential for a wide variety of different applications-from classic gene therapy to genetic vaccination and tumor treatment. However, compared to first-generation adenoviral vectors their production is more complex and requires specific in-depth knowledge. This chapter delivers a detailed protocol for the successful production of HC-Ad vectors to high titers.
Clifford tori and unbiased vectors
NASA Astrophysics Data System (ADS)
Andersson, Ole; Bengtsson, Ingemar
2017-02-01
The existence problem for mutually unbiased bases is an unsolved problem in quantum information theory. A related question is whether every pair of bases admits vectors that are unbiased to both. Mathematically this translates to the question whether two Lagrangian Clifford tori intersect, and a body of results exists concerning it. These results are however rather weak from the point of view of the first problem. We make a detailed study of how the intersections behave in the simplest nontrivial case, that of complex projective 2-space (the qutrit), for which the set of pairs of Clifford tori can be usefully parametrized by the unistochastic subset of Birkhoff's polytope. Pairs that do not intersect transversally are located. Some calculations in higher dimensions are included to see which results are special to the qutrit.
Slow deterministic vector rogue waves
NASA Astrophysics Data System (ADS)
Sergeyev, S. V.; Kolpakov, S. A.; Mou, Ch.; Jacobsen, G.; Popov, S.; Kalashnikov, V.
2016-03-01
For an erbium-doped fiber laser mode-locked by carbon nanotubes, we demonstrate experimentally and theoretically a new type of the vector rogue waves emerging as a result of the chaotic evolution of the trajectories between two orthogonal states of polarization on the Poincare sphere. In terms of fluctuation induced phenomena, by tuning polarization controller for the pump wave and in-cavity polarization controller, we are able to control the Kramers time, i.e. the residence time of the trajectory in vicinity of each orthogonal state of polarization, and so can cause the rare events satisfying rogue wave criteria and having the form of transitions from the state with the long residence time to the state with a short residence time.
Vector wind profile gust model
NASA Technical Reports Server (NTRS)
Adelfang, S. I.
1981-01-01
To enable development of a vector wind gust model suitable for orbital flight test operations and trade studies, hypotheses concerning the distributions of gust component variables were verified. Methods for verification of hypotheses that observed gust variables, including gust component magnitude, gust length, u range, and L range, are gamma distributed and presented. Observed gust modulus has been drawn from a bivariate gamma distribution that can be approximated with a Weibull distribution. Zonal and meridional gust components are bivariate gamma distributed. An analytical method for testing for bivariate gamma distributed variables is presented. Two distributions for gust modulus are described and the results of extensive hypothesis testing of one of the distributions are presented. The validity of the gamma distribution for representation of gust component variables is established.
High power thrust vector actuation
NASA Astrophysics Data System (ADS)
Kittock, M. J.
1993-06-01
Modern missile programs are frequently favoring electro-mechanical (EM) thrust vector actuation (TVA) over hydraulic for a variety of reasons. However, actuation system performance requirements are not relaxed for EM systems. Thus the development of EM systems with greater power output is required. The configuration of EM actuator studied consists of a DC brushless motor driving a spur gear train, which drives a ballscrew that converts rotary motion to rectilinear motion. This design produces an actuator with high levels of performance in a compact mechanical package. Design for manufacturability and assembly (DFMA) was part of the design process, resulting in an actuator that can be assembled easily and will operate reliably. This paper will discuss the mechanical details of the resultant actuator and report test results on a prototype derivative.
Vector wind profile gust model
NASA Technical Reports Server (NTRS)
Adelfang, S. I.
1979-01-01
Work towards establishing a vector wind profile gust model for the Space Transportation System flight operations and trade studies is reported. To date, all the statistical and computational techniques required were established and partially implemented. An analysis of wind profile gust at Cape Kennedy within the theoretical framework is presented. The variability of theoretical and observed gust magnitude with filter type, altitude, and season is described. Various examples are presented which illustrate agreement between theoretical and observed gust percentiles. The preliminary analysis of the gust data indicates a strong variability with altitude, season, and wavelength regime. An extension of the analyses to include conditional distributions of gust magnitude given gust length, distributions of gust modulus, and phase differences between gust components has begun.
Introduction to Vector Field Visualization
NASA Technical Reports Server (NTRS)
Kao, David; Shen, Han-Wei
2010-01-01
Vector field visualization techniques are essential to help us understand the complex dynamics of flow fields. These can be found in a wide range of applications such as study of flows around an aircraft, the blood flow in our heart chambers, ocean circulation models, and severe weather predictions. The vector fields from these various applications can be visually depicted using a number of techniques such as particle traces and advecting textures. In this tutorial, we present several fundamental algorithms in flow visualization including particle integration, particle tracking in time-dependent flows, and seeding strategies. For flows near surfaces, a wide variety of synthetic texture-based algorithms have been developed to depict near-body flow features. The most common approach is based on the Line Integral Convolution (LIC) algorithm. There also exist extensions of LIC to support more flexible texture generations for 3D flow data. This tutorial reviews these algorithms. Tensor fields are found in several real-world applications and also require the aid of visualization to help users understand their data sets. Examples where one can find tensor fields include mechanics to see how material respond to external forces, civil engineering and geomechanics of roads and bridges, and the study of neural pathway via diffusion tensor imaging. This tutorial will provide an overview of the different tensor field visualization techniques, discuss basic tensor decompositions, and go into detail on glyph based methods, deformation based methods, and streamline based methods. Practical examples will be used when presenting the methods; and applications from some case studies will be used as part of the motivation.
Vector Addition: Effect of the Context and Position of the Vectors
NASA Astrophysics Data System (ADS)
Barniol, Pablo; Zavala, Genaro
2010-10-01
In this article we investigate the effect of: 1) the context, and 2) the position of the vectors, on 2D vector addition tasks. We administered a test to 512 students completing introductory physics courses at a private Mexican university. In the first part, we analyze students' responses in three isomorphic problems: displacements, forces, and no physical context. Students were asked to draw two vectors and the vector sum. We analyzed students' procedures detecting the difficulties when drawing the vector addition and proved that the context matters, not only compared to the context-free case but also between the contexts. In the second part, we analyze students' responses with three different arrangements of the sum of two vectors: tail-to-tail, head-to-tail and separated vectors. We compared the frequencies of the errors in the three different positions to deduce students' conceptions in the addition of vectors.
USDA-ARS?s Scientific Manuscript database
The spread of insect vectored pathogens is dependent on the population dynamics of the vector. Epidemiology models typically assume that birth and death rates of pathogen-free and inoculative vectors are equal, an assumption which is not true for all pathosystems. Here a series of simple and gener...
Reversible vector ratchets for skyrmion systems
NASA Astrophysics Data System (ADS)
Ma, X.; Reichhardt, C. J. Olson; Reichhardt, C.
2017-03-01
We show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360∘ rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is always parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.
A Context Vector Model for Information Retrieval.
ERIC Educational Resources Information Center
Billhardt, Holger; Borrajo, Daniel; Maojo, Victor
2002-01-01
Presents an indexing and information retrieval method that, based on the vector space model, incorporates term dependencies and thus obtains semantically richer representations of documents. Highlights include term context vectors; techniques for estimating the dependencies among terms; term weights; experimental results on four text collections;…
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Vectors. 240.206 Section 240.206 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.206 Vectors. ...
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Vectors. 240.206 Section 240.206 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.206 Vectors. ...
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Vectors. 240.206 Section 240.206 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.206 Vectors. ...
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Vectors. 240.206 Section 240.206 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.206 Vectors. ...
Clifford Fourier transform on vector fields.
Ebling, Julia; Scheuermann, Gerik
2005-01-01
Image processing and computer vision have robust methods for feature extraction and the computation of derivatives of scalar fields. Furthermore, interpolation and the effects of applying a filter can be analyzed in detail and can be advantages when applying these methods to vector fields to obtain a solid theoretical basis for feature extraction. We recently introduced the Clifford convolution, which is an extension of the classical convolution on scalar fields and provides a unified notation for the convolution of scalar and vector fields. It has attractive geometric properties that allow pattern matching on vector fields. In image processing, the convolution and the Fourier transform operators are closely related by the convolution theorem and, in this paper, we extend the Fourier transform to include general elements of Clifford Algebra, called multivectors, including scalars and vectors. The resulting convolution and derivative theorems are extensions of those for convolution and the Fourier transform on scalar fields. The Clifford Fourier transform allows a frequency analysis of vector fields and the behavior of vector-valued filters. In frequency space, vectors are transformed into general multivectors of the Clifford Algebra. Many basic vector-valued patterns, such as source, sink, saddle points, and potential vortices, can be described by a few multivectors in frequency space.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Vectors. 240.206 Section 240.206 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES GUIDELINES FOR THE THERMAL PROCESSING OF SOLID WASTES Requirements and Recommended Procedures § 240.206 Vectors....
61 FR 41181 - Vector Supercomputers From Japan
Federal Register 2010, 2011, 2012, 2013, 2014
1996-08-07
... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Vector Supercomputers From Japan AGENCY: United States International Trade Commission. ACTION..., by reason of imports from Japan of vector supercomputers that are alleged to be sold in the...
Natural evolution of neural support vector machines.
Jändel, Magnus
2011-01-01
Two different neural implementations of support vector machines are described and applied to one-shot trainable pattern recognition. The first model is based on oscillating associative memory and is mapped to the olfactory system. The second model is founded on competitive queuing memory originally employed for generating motor action sequences in the brain. Both models include forward pathways where a stream of support vectors is evoked from memory and merges with sensory input to produce support vector machine classifications. Misclassified events are imprinted as new support vector candidates. Support vector machine weights are tuned by virtual experimentation in sleep. Recalled training examples masquerade as sensor input and feedback from the classification process drives a learning process where support vector weights are optimized. For both support vector machine models it is demonstrated that there is a plausible evolutionary path from a simple hard-wired pattern recognizer to a full implementation of a biological kernel machine. Simple and individually beneficial modifications are accumulated in each step along this path. Neural support vector machines can apparently emerge by natural processes.
Application of Vectors to Relative Velocity
ERIC Educational Resources Information Center
Tin-Lam, Toh
2004-01-01
The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…
Student use of vectors in mechanics
NASA Astrophysics Data System (ADS)
Flores, Sergio
A functional understanding of Newton's second law as a vector equation requires that students be able to reason about vectors. In this dissertation, we present data describing students' conceptual difficulties with vector addition and subtraction, and with vector quantities such as force, acceleration and tension. These data suggest that after traditional instruction in introductory physics, some students do not recognize the vector nature of these quantities. Other students who do not have the requisite procedural knowledge to determine net force or acceleration, and are therefore unable to reason qualitatively about Newton's second law. We describe some specific procedural and reasoning difficulties we have observed in students' use of vectors. In addition, we describe modifications to laboratory instruction in mechanics that we designed on the basis of our research into student understanding. These modifications were intended to improve students' understanding of vector addition and subtraction and to promote student use of vectors when solving mechanics problems. Finally, we describe initial measures of the effectiveness of these modifications.
Observation of vector solitons with hidden vorticity.
Izdebskaya, Yana V; Rebling, Johannes; Desyatnikov, Anton S; Kivshar, Yuri S
2012-03-01
This letter reports the first experimental observation, to our knowledge, of optical vector solitons composed of two incoherently coupled vortex components. We employ nematic liquid crystal to generate stable vector solitons with counterrotating vortices and hidden vorticity. In contrast, the solitons with explicit vorticity and corotating vortex components show azimuthal splitting.
Error estimation for ORION baseline vector determination
NASA Technical Reports Server (NTRS)
Wu, S. C.
1980-01-01
Effects of error sources on Operational Radio Interferometry Observing Network (ORION) baseline vector determination are studied. Partial derivatives of delay observations with respect to each error source are formulated. Covariance analysis is performed to estimate the contribution of each error source to baseline vector error. System design parameters such as antenna sizes, system temperatures and provision for dual frequency operation are discussed.
A Context Vector Model for Information Retrieval.
ERIC Educational Resources Information Center
Billhardt, Holger; Borrajo, Daniel; Maojo, Victor
2002-01-01
Presents an indexing and information retrieval method that, based on the vector space model, incorporates term dependencies and thus obtains semantically richer representations of documents. Highlights include term context vectors; techniques for estimating the dependencies among terms; term weights; experimental results on four text collections;…
Reversible vector ratchets for skyrmion systems
Ma, Xiu; Reichhardt, Cynthia Jane Olson; Reichhardt, Charles
2017-03-03
In this paper, we show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360° rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is alwaysmore » parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Finally, since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.« less
Application of Vectors to Relative Velocity
ERIC Educational Resources Information Center
Tin-Lam, Toh
2004-01-01
The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…
Towards Resiliency Evaluation of Vector Programs
Sharma, Vishal C.; Gopalakrishnan, Ganesh; Krishnamoorthy, Sriram
2016-08-04
The systems resilience research community has developed methods to manually insert additional source-program level assertions to trap errors, and also devised tools to conduct fault injection studies for scalar program codes. In this work, we contribute the first vector oriented LLVM-level fault injector VULFI to help study the effects of faults in vector architectures that are of growing importance, especially for vectorizing loops. Using VULFI, we conduct a resiliency study of nine real-world vector benchmarks using Intel’s AVX and SSE extensions as the target vector instruction sets, and offer the first reported understanding of how faults affect vector instruction sets. We take this work further toward automating the insertion of resilience assertions during compilation. This is based on our observation that during intermediate (e.g., LLVM-level) code generation to handle full and partial vectorization, modern compilers exploit (and explicate in their code-documentation) critical invariants. These invariants are turned into error-checking code. We confirm the efficacy of these automatically inserted low-overhead error detectors for vectorized for-loops.
Malaria vector control: from past to future.
Raghavendra, Kamaraju; Barik, Tapan K; Reddy, B P Niranjan; Sharma, Poonam; Dash, Aditya P
2011-04-01
Malaria is one of the most common vector-borne diseases widespread in the tropical and subtropical regions. Despite considerable success of malaria control programs in the past, malaria still continues as a major public health problem in several countries. Vector control is an essential part for reducing malaria transmission and became less effective in recent years, due to many technical and administrative reasons, including poor or no adoption of alternative tools. Of the different strategies available for vector control, the most successful are indoor residual spraying and insecticide-treated nets (ITNs), including long-lasting ITNs and materials. Earlier DDT spray has shown spectacular success in decimating disease vectors but resulted in development of insecticide resistance, and to control the resistant mosquitoes, organophosphates, carbamates, and synthetic pyrethroids were introduced in indoor residual spraying with needed success but subsequently resulted in the development of widespread multiple insecticide resistance in vectors. Vector control in many countries still use insecticides in the absence of viable alternatives. Few developments for vector control, using ovitraps, space spray, biological control agents, etc., were encouraging when used in limited scale. Likewise, recent introduction of safer vector control agents, such as insect growth regulators, biocontrol agents, and natural plant products have yet to gain the needed scale of utility for vector control. Bacterial pesticides are promising and are effective in many countries. Environmental management has shown sufficient promise for vector control and disease management but still needs advocacy for inter-sectoral coordination and sometimes are very work-intensive. The more recent genetic manipulation and sterile insect techniques are under development and consideration for use in routine vector control and for these, standardized procedures and methods are available but need thorough
Viral Vector Biosafety in Laboratory Animal Research.
Collins, Dalis E; Reuter, Jon D; Rush, Howard G; Villano, Jason S
2017-06-01
Viral vector research presents unique occupational health and safety challenges to institutions due to the rapid development of both in vivo and in vitro gene-editing technologies. Risks to human and animal health make it incumbent on institutions to appropriately evaluate viral vector usage in research on the basis of available information and governmental regulations and guidelines. Here we review the factors related to risk assessment regarding viral vector usage in animals and the relevant regulatory documents associated with this research, and we highlight the most commonly used viral vectors in research today. This review is particularly focused on the background, use in research and associated health and environmental risks related to adenoviral, adeno-associated viral, lentiviral, and herpesviral vectors.
Control of phlebotomine (Diptera: Psychodidae) leishmaniasis vectors.
Amóra, Sthenia S A; Bevilaqua, Claudia M L; Feijó, Francisco M C; D Alves, Nilza; do V Maciel, Michelline
2009-01-01
Phlebotomines are of medical and veterinary concern as they vector leishmaniasis, bartonellosis and some arboviruses. The adaptations of some species to places modified by humans bring these vectors into contact with dwellings, which can facilitate disease transmission, and the vector control strategies adopted have rendered controversial results. Regarding leishmaniasis, for instance, which vector and reservoirs control can be effective, there is an assumption that the incidence of human infection is directly related to the number of infectious dogs, as well as to entomological factors. Therefore, vector control can provide a cheaper and more practical solution to prevent cases of leishmaniasis. Nevertheless, due to the complexity of the factors involved, chemical control is still essential, and biological insecticides and insecticide plants, for example, represent areas for study that should be encouraged and developed since they show promising results. This paper summarizes the control strategies adopted so far, especially the methods and efficiency of the entomological components of leishmaniasis control programs.
Localizing viruses in their insect vectors.
Blanc, Stéphane; Drucker, Martin; Uzest, Marilyne
2014-01-01
The mechanisms and impacts of the transmission of plant viruses by insect vectors have been studied for more than a century. The virus route within the insect vector is amply documented in many cases, but the identity, the biochemical properties, and the structure of the actual molecules (or molecule domains) ensuring compatibility between them remain obscure. Increased efforts are required both to identify receptors of plant viruses at various sites in the vector body and to design competing compounds capable of hindering transmission. Recent trends in the field are opening questions on the diversity and sophistication of viral adaptations that optimize transmission, from the manipulation of plants and vectors ultimately increasing the chances of acquisition and inoculation, to specific "sensing" of the vector by the virus while still in the host plant and the subsequent transition to a transmission-enhanced state.
Vector Diffusion Maps and the Connection Laplacian
Singer, A.; Wu, H.-T.
2013-01-01
We introduce vector diffusion maps (VDM), a new mathematical framework for organizing and analyzing massive high-dimensional data sets, images, and shapes. VDM is a mathematical and algorithmic generalization of diffusion maps and other nonlinear dimensionality reduction methods, such as LLE, ISOMAP, and Laplacian eigenmaps. While existing methods are either directly or indirectly related to the heat kernel for functions over the data, VDM is based on the heat kernel for vector fields. VDM provides tools for organizing complex data sets, embedding them in a low-dimensional space, and interpolating and regressing vector fields over the data. In particular, it equips the data with a metric, which we refer to as the vector diffusion distance. In the manifold learning setup, where the data set is distributed on a low-dimensional manifold ℳd embedded in ℝp, we prove the relation between VDM and the connection Laplacian operator for vector fields over the manifold. PMID:24415793
Axial vector Z‧ and anomaly cancellation
NASA Astrophysics Data System (ADS)
Ismail, Ahmed; Keung, Wai-Yee; Tsao, Kuo-Hsing; Unwin, James
2017-05-01
Whilst the prospect of new Z‧ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that in a large class of models masses of these new states are expected to be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.
Bacteriophage gene targeting vectors generated by transplacement.
Aoyama, C; Woltjen, K; Mansergh, F C; Ishidate, K; Rancourt, D E
2002-10-01
A rate-determining step in gene targeting is the generation of the targeting vector. We have developed bacteriophage gene targeting vectorology, which shortens the timeline of targeting vector construction. Using retro-recombination screening, we can rapidly isolate targeting vectors from an embryonic stem cell genomic library via integrative and excisive recombination. We have demonstrated that recombination can be used to introduce specific point mutations or unique restriction sites into gene targeting vectors via transplacement. Using the choline/ethanolamine kinase alpha and beta genes as models, we demonstrate that transplacement can also be used to introduce specifically a neo resistance cassette into a gene targeting phage. In our experience, the lambdaTK gene targeting system offers considerable flexibility and efficiency in TV construction, which makes generating multiple vectors in one week's time possible.
Developments in Viral Vector-Based Vaccines
Ura, Takehiro; Okuda, Kenji; Shimada, Masaru
2014-01-01
Viral vectors are promising tools for gene therapy and vaccines. Viral vector-based vaccines can enhance immunogenicity without an adjuvant and induce a robust cytotoxic T lymphocyte (CTL) response to eliminate virus-infected cells. During the last several decades, many types of viruses have been developed as vaccine vectors. Each has unique features and parental virus-related risks. In addition, genetically altered vectors have been developed to improve efficacy and safety, reduce administration dose, and enable large-scale manufacturing. To date, both successful and unsuccessful results have been reported in clinical trials. These trials provide important information on factors such as toxicity, administration dose tolerated, and optimized vaccination strategy. This review highlights major viral vectors that are the best candidates for clinical use. PMID:26344749
Computational Investigation of Fluidic Counterflow Thrust Vectoring
NASA Technical Reports Server (NTRS)
Hunter, Craig A.; Deere, Karen A.
1999-01-01
A computational study of fluidic counterflow thrust vectoring has been conducted. Two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and linear Reynolds stress modeling. For validation, computational results were compared to experimental data obtained at the NASA Langley Jet Exit Test Facility. In general, computational results were in good agreement with experimental performance data, indicating that efficient thrust vectoring can be obtained with low secondary flow requirements (less than 1% of the primary flow). An examination of the computational flowfield has revealed new details about the generation of a countercurrent shear layer, its relation to secondary suction, and its role in thrust vectoring. In addition to providing new information about the physics of counterflow thrust vectoring, this work appears to be the first documented attempt to simulate the counterflow thrust vectoring problem using computational fluid dynamics.
Gauge vectors and double beta decay
NASA Astrophysics Data System (ADS)
Fonseca, Renato M.; Hirsch, Martin
2017-02-01
We discuss contributions to neutrinoless double beta (0 ν β β ) decay involving vector bosons. The starting point is a list of all possible vector representations that may contribute to 0 ν β β decay via d =9 or d =11 operators at tree level. We then identify gauge groups which contain these vectors in the adjoint representation. Even though the complete list of vector fields that can contribute to 0 ν β β up to d =11 is large (a total of 46 vectors), only a few of them can be gauge bosons of phenomenologically realistic groups. These latter cases are discussed in some more detail, and lower (upper) limits on gauge boson masses (mixing angles) are derived from the absence of 0 ν β β decay.
Molecular genetic manipulation of mosquito vectors.
Carlson, J; Olson, K; Higgs, S; Beaty, B
1995-01-01
Despite their central role in disease transmission, relatively little is known of the molecular biology of arthropod vectors. Modern molecular approaches will undoubtedly provide considerable information about gene regulation and expression in vectors and consequently a much better understanding of the biology and molecular biology of vectors. Such knowledge is essential for developing effective control strategies for vector-borne diseases. In this review, we focus upon techniques and approaches used at the Arthropod-Borne and Infectious Diseases Laboratory (AIDL) at Colorado State University to bioengineer mosquitoes with reduced vector competence. We have developed technologies and procedures that allow genetic manipulation of mosquitoes, including RNA and DNA virus gene-delivery vehicles and efficacious antiviral constructs, which will facilitate the development of pathogen-resistant, transformed mosquitoes. Many of the approaches, constructs, and technologies developed at AIDL will be applicable to molecular manipulation of other arthropod genomes.
Alphavirus vectors for cancer gene therapy (review).
Yamanaka, Ryuya
2004-04-01
Alphaviruses have several characteristics that make them attractive as gene therapy vectors such as transient and high-level expression of a heterologous gene. Alphavirus vectors, Semliki Forest virus (SFV), Sindbis virus (SIN) and Venezuelan equine encephalitis virus (VEE) have been developed as gene expression vectors. Alphaviruses are positive-strand RNA viruses that can mediate efficient cytoplasmic gene expression in mammalian cells. The alphavirus RNA replication machinery has been engineered for high level heterologous gene expression. Since an RNA virus vector cannot integrate into chromosomal DNA, concerns about cell transformation are reduced. Alphavirus vectors demonstrate promise for the safe tumor-killing and tumor-specific immune responses. Recombinant alphavirus RNA replicons may facilitate gene therapy of cancer.
Geoacoustic inversion using the vector field
NASA Astrophysics Data System (ADS)
Crocker, Steven E.
The main goal of this project was to study the use of the acoustic vector field, separately or in combination with the scalar field, to estimate the depth dependent geoacoustic properties of the seafloor via non-linear inversion. The study was performed in the context of the Sediment Acoustics Experiment 2004 (SAX04) conducted in the Northern Gulf of Mexico (GOM) where a small number of acoustic vector sensors were deployed in close proximity to the seafloor. A variety of acoustic waveforms were transmitted into the seafloor at normal incidence. The acoustic vector sensors were located both above and beneath the seafloor interface where they measured the acoustic pressure and the acoustic particle acceleration. Motion data provided by the buried vector sensors were affected by a suspension response that was sensitive to the mass properties of the sensor, the sediment density and sediment elasticity (e.g., shear wave speed). The suspension response for the buried vector sensors included a resonance within the analysis band of 0.4 to 2.0 kHz. The suspension resonance represented an unknown complex transfer function between the acoustic vector field in the seabed and data representing that field. Therefore, inverse methods developed for this study were required to 1) estimate dynamic properties of the sensor suspension resonance and 2) account for the associated corruption of vector field data. A method to account for the vector sensor suspense response function was integrated directly into the inversion methods such that vector channel data corruption was reduced and an estimate of the shear wave speed in the sediment was returned. Inversions of real and synthetic data sets indicated that information about sediment shear wave speed was carried by the suspension response of the buried sensors, as opposed to being contained inherently within the acoustic vector field.
Poxviral vectors for cancer immunotherapy
Kim, Joseph W.; Gulley, James L.
2012-01-01
Introduction Poxviral vaccines have been given to over 1 billion people in the successful global eradication of smallpox. Since then, recombinant poxviruses have been investigated extensively as a novel immunotherapy for cancer, undergoing several iterations to optimize their immunogenicity and efficacy. The current platform expressing multiple costimulatory molecules plus a tumor-associated antigen such as PSA, i.e., PSA-TRICOM (PROSTVAC-V/F), is promising and is currently in a phase III randomized, placebo-controlled clinical trial in metastatic castration-resistant prostate cancer. Areas covered This review discusses the clinical development of poxviral-based cancer vaccines, with a particular focus on the rationale for combining vaccines with other treatment modalities, including radiotherapy, chemotherapy, hormonal therapy, other immune-based therapies, and molecularly targeted therapy. We also discuss the importance of appropriate patient selection in clinical trial design. Expert Opinion Preclinical and early clinical studies with poxviral vector vaccines have shown promising results with this novel immunologic approach both as vaccine alone and combined with other therapies. The challenges of translating the science of immunotherapy to clinical practice include clinical trial design that includes appropriate patient selection, appropriate endpoints, and identification of meaningful surrogate biomarkers. PMID:22413824
GRASS GIS Vector Processing: Towards GRASS 7
NASA Astrophysics Data System (ADS)
Metz, Markus; Landa, Martin; Petrasova, Anna; Petras, Vaclav; Chemin, Yann; Neteler, Markus
2014-05-01
The upcoming GRASS GIS 7 release improves not only raster processing and general design but the vector processing in the first place. GRASS GIS, as a topological GIS, recognizes that the topology plays the key role in the vector processing and analysis. Topology ensures that adjacent geographic components in a single vector map are related. In contrast to non-topological GIS, a border common to two areas exists only once and is shared between the two areas. Topological representation of vector data helps to produce and maintain vector maps with clean geometry as well as enables the user to perform certain analyses that can not be conducted with non-topological or spaghetti data. Non-topological vector data are automatically converted to a topological representation upon import. Further more, various cleaning tools exist to remove non-trivial topological errors. In the upcoming GRASS GIS 7 release the vector library was particularly improved to make it faster and more efficient with an improved internal vector file format. This new topological format reduces memory and disk space requirements, leading to a generally faster processing. Opening an existing vector requires less memory providing additionally support for large files. The new spatial index performs queries faster (compared to GRASS GIS 6 more than 10 times for large vectors). As a new option the user can select a file-based version of the spatial index for large vector data. All topological cleaning tools have been optimized with regard to processing speed, robustness, and system requirements. The topological engine comes with a new prototype for direct read/write support of Simple Features API/OGR. Additionally vector data can be directly exchanged with topological PostGIS 2 databases. Considering the wide spread usage of ESRI Shapefile, a non-topological format for vector data exchange, it is particularly advantageous that GRASS GIS 7 offers advanced cleaning tools. For power users and programmers, the
Image Coding Based on Address Vector Quantization.
NASA Astrophysics Data System (ADS)
Feng, Yushu
Image coding is finding increased application in teleconferencing, archiving, and remote sensing. This thesis investigates the potential of Vector Quantization (VQ), a relatively new source coding technique, for compression of monochromatic and color images. Extensions of the Vector Quantization technique to the Address Vector Quantization method have been investigated. In Vector Quantization, the image data to be encoded are first processed to yield a set of vectors. A codeword from the codebook which best matches the input image vector is then selected. Compression is achieved by replacing the image vector with the index of the code-word which produced the best match, the index is sent to the channel. Reconstruction of the image is done by using a table lookup technique, where the label is simply used as an address for a table containing the representative vectors. A code-book of representative vectors (codewords) is generated using an iterative clustering algorithm such as K-means, or the generalized Lloyd algorithm. A review of different Vector Quantization techniques are given in chapter 1. Chapter 2 gives an overview of codebook design methods including the Kohonen neural network to design codebook. During the encoding process, the correlation of the address is considered and Address Vector Quantization is developed for color image and monochrome image coding. Address VQ which includes static and dynamic processes is introduced in chapter 3. In order to overcome the problems in Hierarchical VQ, Multi-layer Address Vector Quantization is proposed in chapter 4. This approach gives the same performance as that of the normal VQ scheme but the bit rate is about 1/2 to 1/3 as that of the normal VQ method. In chapter 5, a Dynamic Finite State VQ based on a probability transition matrix to select the best subcodebook to encode the image is developed. In chapter 6, a new adaptive vector quantization scheme, suitable for color video coding, called "A Self -Organizing
A recursive technique for adaptive vector quantization
NASA Technical Reports Server (NTRS)
Lindsay, Robert A.
1989-01-01
Vector Quantization (VQ) is fast becoming an accepted, if not preferred method for image compression. The VQ performs well when compressing all types of imagery including Video, Electro-Optical (EO), Infrared (IR), Synthetic Aperture Radar (SAR), Multi-Spectral (MS), and digital map data. The only requirement is to change the codebook to switch the compressor from one image sensor to another. There are several approaches for designing codebooks for a vector quantizer. Adaptive Vector Quantization is a procedure that simultaneously designs codebooks as the data is being encoded or quantized. This is done by computing the centroid as a recursive moving average where the centroids move after every vector is encoded. When computing the centroid of a fixed set of vectors the resultant centroid is identical to the previous centroid calculation. This method of centroid calculation can be easily combined with VQ encoding techniques. The defined quantizer changes after every encoded vector by recursively updating the centroid of minimum distance which is the selected by the encoder. Since the quantizer is changing definition or states after every encoded vector, the decoder must now receive updates to the codebook. This is done as side information by multiplexing bits into the compressed source data.
Wavelet frame accelerated reduced support vector machines.
Ratsch, Matthias; Teschke, Gerd; Romdhani, Sami; Vetter, Thomas
2008-12-01
In this paper, a novel method for reducing the runtime complexity of a support vector machine classifier is presented. The new training algorithm is fast and simple. This is achieved by an over-complete wavelet transform that finds the optimal approximation of the support vectors. The presented derivation shows that the wavelet theory provides an upper bound on the distance between the decision function of the support vector machine and our classifier. The obtained classifier is fast, since a Haar wavelet approximation of the support vectors is used, enabling efficient integral image-based kernel evaluations. This provides a set of cascaded classifiers of increasing complexity for an early rejection of vectors easy to discriminate. This excellent runtime performance is achieved by using a hierarchical evaluation over the number of incorporated and additional over the approximation accuracy of the reduced set vectors. Here, this algorithm is applied to the problem of face detection, but it can also be used for other image-based classifications. The algorithm presented, provides a 530-fold speedup over the support vector machine, enabling face detection at more than 25 fps on a standard PC.
HSV Recombinant Vectors for Gene Therapy
Manservigi, Roberto; Argnani, Rafaela; Marconi, Peggy
2010-01-01
The very deep knowledge acquired on the genetics and molecular biology of herpes simplex virus (HSV), has allowed the development of potential replication-competent and replication-defective vectors for several applications in human healthcare. These include delivery and expression of human genes to cells of the nervous systems, selective destruction of cancer cells, prophylaxis against infection with HSV or other infectious diseases, and targeted infection to specific tissues or organs. Replication-defective recombinant vectors are non-toxic gene transfer tools that preserve most of the neurotropic features of wild type HSV-1, particularly the ability to express genes after having established latent infections, and are thus proficient candidates for therapeutic gene transfer settings in neurons. A replication-defective HSV vector for the treatment of pain has recently entered in phase 1 clinical trial. Replication-competent (oncolytic) vectors are becoming a suitable and powerful tool to eradicate brain tumours due to their ability to replicate and spread only within the tumour mass, and have reached phase II/III clinical trials in some cases. The progress in understanding the host immune response induced by the vector is also improving the use of HSV as a vaccine vector against both HSV infection and other pathogens. This review briefly summarizes the obstacle encountered in the delivery of HSV vectors and examines the various strategies developed or proposed to overcome such challenges. PMID:20835362
Acoustic pressure-vector sensor array
NASA Astrophysics Data System (ADS)
Huang, Dehua; Elswick, Roy C.; McEachern, James F.
2004-05-01
Pressure-vector sensors measure both scalar and vector components of the acoustic field. December 2003 measurements at the NUWC Seneca Lake test facility verify previous observations that acoustic ambient noise spectrum levels measured by acoustic intensity sensors are reduced relative to either acoustic pressure or acoustic vector sensor spectrum levels. The Seneca measurements indicate a reduction by as much as 15 dB at the upper measurement frequency of 2500 Hz. A nonlinear array synthesis theory for pressure-vector sensors will be introduced that allows smaller apertures to achieve narrow beams. The significantly reduced ambient noise of individual pressure-vector elements observed in the ocean by others, and now at Seneca Lake, should allow a nonlinearly combined array to detect significantly lower levels than has been observed in previous multiplicative processing of pressure sensors alone. Nonlinear array synthesis of pressure-vector sensors differs from conventional super-directive algorithms that linearly combine pressure elements with positive and negative weights, thereby reducing the sensitivity of conventional super-directive arrays. The much smaller aperture of acoustic pressure-vector sensor arrays will be attractive for acoustic systems on underwater vehicles, as well as for other applications that require narrow beam acoustic receivers. [The authors gratefully acknowledge the support of ONR and NUWC.
Intracellular trafficking of hybrid gene delivery vectors.
Keswani, Rahul K; Lazebnik, Mihael; Pack, Daniel W
2015-06-10
Viral and non-viral gene delivery vectors are in development for human gene therapy, but both exhibit disadvantages such as inadequate efficiency, lack of cell-specific targeting or safety concerns. We have recently reported the design of hybrid delivery vectors combining retrovirus-like particles with synthetic polymers or lipids that are efficient, provide sustained gene expression and are more stable compared to native retroviruses. To guide further development of this promising class of gene delivery vectors, we have investigated their mechanisms of intracellular trafficking. Moloney murine leukemia virus-like particles (M-VLPs) were complexed with chitosan (Chi) or liposomes (Lip) comprising DOTAP, DOPE and cholesterol to form the hybrid vectors (Chi/M-VLPs and Lip/M-VLPs, respectively). Transfection efficiency and cellular internalization of the vectors were quantified in the presence of a panel of inhibitors of various endocytic pathways. Intracellular transport and trafficking kinetics of the hybrid vectors were dependent on the synthetic component and used a combination of clathrin- and caveolar-dependent endocytosis and macropinocytosis. Chi/M-VLPs were slower to transfect compared to Lip/M-VLPs due to the delayed detachment of the synthetic component. The synthetic component of hybrid gene delivery vectors plays a significant role in their cellular interactions and processing and is a key parameter for the design of more efficient gene delivery vehicles.
Foamy Virus Vectors for HIV Gene Therapy
Olszko, Miles E.; Trobridge, Grant D.
2013-01-01
Highly active antiretroviral therapy (HAART) has vastly improved outcomes for patients infected with HIV, yet it is a lifelong regimen that is expensive and has significant side effects. Retroviral gene therapy is a promising alternative treatment for HIV/AIDS; however, inefficient gene delivery to hematopoietic stem cells (HSCs) has so far limited the efficacy of this approach. Foamy virus (FV) vectors are derived from non-pathogenic viruses that are not endemic to the human population. FV vectors have been used to deliver HIV-inhibiting transgenes to human HSCs, and they have several advantages relative to other retroviral vectors. These include an attractive safety profile, broad tropism, a large transgene capacity, and the ability to persist in quiescent cells. In addition, the titers of FV vectors are not reduced by anti-HIV transgenes that affect the production of lentivirus (LV) vectors. Thus FV vectors are very promising for anti-HIV gene therapy. This review covers the advantages of FV vectors and describes their preclinical development for anti-HIV gene therapy. PMID:24153061
Vector curvaton with varying kinetic function
Dimopoulos, Konstantinos; Karciauskas, Mindaugas; Wagstaff, Jacques M.
2010-01-15
A new model realization of the vector curvaton paradigm is presented and analyzed. The model consists of a single massive Abelian vector field, with a Maxwell-type kinetic term. By assuming that the kinetic function and the mass of the vector field are appropriately varying during inflation, it is shown that a scale-invariant spectrum of superhorizon perturbations can be generated. These perturbations can contribute to the curvature perturbation of the Universe. If the vector field remains light at the end of inflation it is found that it can generate substantial statistical anisotropy in the spectrum and bispectrum of the curvature perturbation. In this case the non-Gaussianity in the curvature perturbation is predominantly anisotropic, which will be a testable prediction in the near future. If, on the other hand, the vector field is heavy at the end of inflation then it is demonstrated that particle production is approximately isotropic and the vector field alone can give rise to the curvature perturbation, without directly involving any fundamental scalar field. The parameter space for both possibilities is shown to be substantial. Finally, toy models are presented which show that the desired variation of the mass and kinetic function of the vector field can be realistically obtained, without unnatural tunings, in the context of supergravity or superstrings.
Theodolite-borne vector Overhauser magnetometer: DIMOVER
NASA Astrophysics Data System (ADS)
Sapunov, V.; Rasson, J.; Denisov, A.; Saveliev, D.; Kiselev, S.; Denisova, O.; Podmogov, Y.; Khomutov, S.
2006-06-01
This report covers results of the long-term research directed at developing an absolute vector proton magnetometer based on the switching of bias magnetic fields. The distinctive feature is the attempt of the installation of a miniature Overhauser sensor and optimized Garret solenoid directly on the telescope of the theodolite. Thus this design (Declination Inclination Modulus Overhauser magnetometer: DIMOVER) will complement the universally recognised DIflux absolute device by adding full vector measurement capability. Preliminary designs, which also can be interesting to the experts in vector proton magnetometers, are presented.
Recursive algorithms for vector extrapolation methods
NASA Technical Reports Server (NTRS)
Ford, William F.; Sidi, Avram
1988-01-01
Three classes of recursion relations are devised for implementing some extrapolation methods for vector sequences. One class of recursion relations can be used to implement methods like the modified minimal polynomial extrapolation and the topological epsilon algorithm; another allows implementation of methods like minimal polynomial and reduced rank extrapolation; while the remaining class can be employed in the implementation of the vector E-algorithm. Operation counts and storage requirements for these methods are also discussed, and some related techniques for special applications are also presented. Included are methods for the rapid evaluations of the vector E-algorithm.
Robust vector quantization for noisy channels
NASA Technical Reports Server (NTRS)
Demarca, J. R. B.; Farvardin, N.; Jayant, N. S.; Shoham, Y.
1988-01-01
The paper briefly discusses techniques for making vector quantizers more tolerant to tranmsission errors. Two algorithms are presented for obtaining an efficient binary word assignment to the vector quantizer codewords without increasing the transmission rate. It is shown that about 4.5 dB gain over random assignment can be achieved with these algorithms. It is also proposed to reduce the effects of error propagation in vector-predictive quantizers by appropriately constraining the response of the predictive loop. The constrained system is shown to have about 4 dB of SNR gain over an unconstrained system in a noisy channel, with a small loss of clean-channel performance.
600-GHz Electronically Tunable Vector Measurement System
NASA Technical Reports Server (NTRS)
Dengler, Robert; Maiwald, Frank; Siegel, Peter
2007-01-01
A compact, high-dynamic-range, electronically tunable vector measurement system that operates in the frequency range from approximately 560 to approximately 635 GHz has been developed as a prototype of vector measurement systems that would be suitable for use in nearly-real-time active submillimeter-wave imaging. As used here, 'vector measurement system" signifies an instrumentation system that applies a radio-frequency (RF) excitation to an object of interest and measures the resulting amplitude and phase response, relative to either the applied excitatory signal or another reference signal related in a known way to applied excitatory signal.
Engineering targeted viral vectors for gene therapy.
Waehler, Reinhard; Russell, Stephen J; Curiel, David T
2007-08-01
To achieve therapeutic success, transfer vehicles for gene therapy must be capable of transducing target cells while avoiding impact on non-target cells. Despite the high transduction efficiency of viral vectors, their tropism frequently does not match the therapeutic need. In the past, this lack of appropriate targeting allowed only partial exploitation of the great potential of gene therapy. Substantial progress in modifying viral vectors using diverse techniques now allows targeting to many cell types in vitro. Although important challenges remain for in vivo applications, the first clinical trials with targeted vectors have already begun to take place.
Generating Series for Nested Bethe Vectors
NASA Astrophysics Data System (ADS)
Khoroshkin, Sergey; Pakuliak, Stanislav
2008-11-01
We reformulate nested relations between off-shell Uq(^glN) Bethe vectors as a certain equation on generating series of strings of the composed Uq(^glN) currents. Using inversion of the generating series we find a new type of hierarchical relations between universal off-shell Bethe vectors, useful for a derivation of Bethe equation. As an example of application, we use these relations for a derivation of analytical Bethe ansatz equations [Arnaudon D. et al., Ann. Henri Poincaré 7 (2006), 1217-1268, math-ph/0512037] for the parameters of universal Bethe vectors of the algebra Uq(^gl2).
Hard Exclusive Vector Meson Leptoproduction At HERMES
Golembiovskaya, M.
2011-07-15
The HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson ({rho}{sup 0}{phi},{omega}) leptoproduction using the 27.6 GeV longitudinally polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas targets. Measurements of exclusive vector meson production provide access to the structure of the nucleon since the process can be described in terms of Generalized Parton Distributions (GPDs). An overview of the HERMES results on exclusive vector mesons production is presented.
Kaur, Navneet; Hasegawa, Daniel K; Ling, Kai-Shu; Wintermantel, William M
2016-10-01
The relationships between plant viruses and their vectors have evolved over the millennia, and yet, studies on viruses began <150 years ago and investigations into the virus and vector interactions even more recently. The advent of next generation sequencing, including rapid genome and transcriptome analysis, methods for evaluation of small RNAs, and the related disciplines of proteomics and metabolomics offer a significant shift in the ability to elucidate molecular mechanisms involved in virus infection and transmission by insect vectors. Genomic technologies offer an unprecedented opportunity to examine the response of insect vectors to the presence of ingested viruses through gene expression changes and altered biochemical pathways. This review focuses on the interactions between viruses and their whitefly or thrips vectors and on potential applications of genomics-driven control of the insect vectors. Recent studies have evaluated gene expression in vectors during feeding on plants infected with begomoviruses, criniviruses, and tospoviruses, which exhibit very different types of virus-vector interactions. These studies demonstrate the advantages of genomics and the potential complementary studies that rapidly advance our understanding of the biology of virus transmission by insect vectors and offer additional opportunities to design novel genetic strategies to manage insect vectors and the viruses they transmit.
Ledesma, Nicholas; Harrington, Laura
2011-11-01
Dog heartworm (Dirofilaria immitis) is dependent on mosquito vectors for its maintenance and transmission among vertebrate hosts. Consequently, D. immitis abundance and distribution are closely linked with mosquito vector biology and ecology. Information on the important dog heartworm vectors in the United States is limited and no comprehensive surveillance of dog heartworm in US mosquitoes has been undertaken to date. Here, we review information gleaned from a number of field surveys documenting heartworm presence in wild mosquito populations as well as laboratory assessments of mosquito vector capacity. Various biological and ecological factors likely contribute to the relative importance of different vector species. We describe some of these factors, rank the leading criteria for efficient vectors, and present the most likely vector species found across the United States. Considering the recent emergence of drug resistance among D. immitis strains, practical knowledge of heartworm vector biology and control should be incorporated into heartworm disease management programs. We conclude by proposing that heartworm control would benefit by targeting mosquito vectors, and we suggest ways in which veterinarians can incorporate the recognition of vector importance into heartworm prevention recommendations imparted to clients. Copyright © 2011 Elsevier Inc. All rights reserved.
Gene therapy using retrovirus vectors: vector development and biosafety at clinical trials.
Doi, Knayo; Takeuchi, Yasuhiro
2015-01-01
Retrovirus vectors (gammaretroviral and lentiviral vectors) have been considered as promising tools to transfer therapeutic genes into patient cells because they can permanently integrate into host cellular genome. To treat monogenic, inherited diseases, retroviral vectors have been used to add correct genes into patient cells. Conventional gammaretroviral vectors achieved successful results in clinical trials: treated patients had therapeutic gene expression in target cells and had improved symptoms of diseases. However, serious side-effects of leukemia occurred, caused by retroviral insertional mutagenesis (IM). These incidences stressed the importance of monitoring vector integration sites in patient cells as well as of re-consideration on safer vectors. More recently lentiviral vectors which can deliver genes into non-dividing cells started to be used in clinical trials including neurological disorders, showing their efficacy. Vector integration site analysis revealed that lentiviruses integrate less likely to near promoter regions of oncogenes than gammaretroviruses and no adverse events have been reported in lentiviral vector-mediated gene therapy clinical trials. Therefore lentiviral vectors have promises to be applied to a wide range of common diseases in near future. For example, T cells from cancer patients were transduced to express chimeric T cell receptors recognizing their tumour cells enhancing patients' anti-cancer immunity.
TWSVR: Regression via Twin Support Vector Machine.
Khemchandani, Reshma; Goyal, Keshav; Chandra, Suresh
2016-02-01
Taking motivation from Twin Support Vector Machine (TWSVM) formulation, Peng (2010) attempted to propose Twin Support Vector Regression (TSVR) where the regressor is obtained via solving a pair of quadratic programming problems (QPPs). In this paper we argue that TSVR formulation is not in the true spirit of TWSVM. Further, taking motivation from Bi and Bennett (2003), we propose an alternative approach to find a formulation for Twin Support Vector Regression (TWSVR) which is in the true spirit of TWSVM. We show that our proposed TWSVR can be derived from TWSVM for an appropriately constructed classification problem. To check the efficacy of our proposed TWSVR we compare its performance with TSVR and classical Support Vector Regression(SVR) on various regression datasets.
Modeling material failure with a vectorized routine
NASA Technical Reports Server (NTRS)
Cramer, S. M.; Goodman, J. R.
1984-01-01
The computational aspects of modelling material failure in structural wood members are presented with particular reference to vector processing aspects. Wood members are considered to be highly orthotropic, inhomogeneous, and discontinuous due to the complex microstructure of wood material and the presence of natural growth characteristics such as knots, cracks and cross grain in wood members. The simulation of strength behavior of wood members is accomplished through the use of a special purpose finite element/fracture mechanics routine, program STARW (Strength Analysis Routine for Wood). Program STARW employs quadratic finite elements combined with singular crack tip elements in a finite element mesh. Vector processing techniques are employed in mesh generation, stiffness matrix formation, simultaneous equation solution, and material failure calculations. The paper addresses these techniques along with the time and effort requirements needed to convert existing finite element code to a vectorized version. Comparisons in execution time between vectorized and nonvectorized routines are provided.
Integrated epidemiology for vector-borne zoonoses.
Wardrop, Nicola A
2016-02-01
The development and application of interventions for the control of vector-borne zoonoses requires broad understanding of epidemiological linkages between vector, animal infection and human infection. However, there are significant gaps in our understanding of these linkages and a lack of appropriate data poses a considerable barrier to addressing this issue. A move towards strengthened surveillance of vectors and disease in both animal and human hosts, in combination with linked human-animal surveys, could form the backbone for epidemiological integration, enabling explicit assessment of the animal-human (and vector) interface, and subsequent implications for spill-over to human populations. Currently available data on the spatial distribution of human African trypanosomiasis allow an illustrative example.
Magnetic vector field tag and seal
Johnston, Roger G.; Garcia, Anthony R.
2004-08-31
One or more magnets are placed in a container (preferably on objects inside the container) and the magnetic field strength and vector direction are measured with a magnetometer from at least one location near the container to provide the container with a magnetic vector field tag and seal. The location(s) of the magnetometer relative to the container are also noted. If the position of any magnet inside the container changes, then the measured vector fields at the these locations also change, indicating that the tag has been removed, the seal has broken, and therefore that the container and objects inside may have been tampered with. A hollow wheel with magnets inside may also provide a similar magnetic vector field tag and seal. As the wheel turns, the magnets tumble randomly inside, removing the tag and breaking the seal.
Extracting Road Vector Data from Raster Maps
NASA Astrophysics Data System (ADS)
Chiang, Yao-Yi; Knoblock, Craig A.
Raster maps are an important source of road information. Because of the overlapping map features (e.g., roads and text labels) and the varying image quality, extracting road vector data from raster maps usually requires significant user input to achieve accurate results. In this paper, we present an accurate road vectorization technique that minimizes user input by combining our previous work on extracting road pixels and road-intersection templates to extract accurate road vector data from raster maps. Our approach enables GIS applications to exploit the road information in raster maps for the areas where the road vector data are otherwise not easily accessible, such as the countries of the Middle East. We show that our approach requires minimal user input and achieves an average of 93.2% completeness and 95.6% correctness in an experiment using raster maps from various sources.
VEST: Abstract Vector Calculus Simplification in Mathematica
J. Squire, J. Burby and H. Qin
2013-03-12
We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce scalar and vector expressions of a very general type using a systematic canonicalization procedure. In addition, utilizing properties of the Levi-Civita symbol, the program can derive types of multi-term vector identities that are not recognized by canonicalization, subsequently applying these to simplify large expressions. In a companion paper [1], we employ VEST in the automation of the calculation of Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations. __________________________________________________
Students' difficulties with vector calculus in electrodynamics
NASA Astrophysics Data System (ADS)
Bollen, Laurens; van Kampen, Paul; De Cock, Mieke
2015-12-01
Understanding Maxwell's equations in differential form is of great importance when studying the electrodynamic phenomena discussed in advanced electromagnetism courses. It is therefore necessary that students master the use of vector calculus in physical situations. In this light we investigated the difficulties second year students at KU Leuven encounter with the divergence and curl of a vector field in mathematical and physical contexts. We have found that they are quite skilled at doing calculations, but struggle with interpreting graphical representations of vector fields and applying vector calculus to physical situations. We have found strong indications that traditional instruction is not sufficient for our students to fully understand the meaning and power of Maxwell's equations in electrodynamics.
[Gene engineering of the adenovirus vector].
Kondo, Saki; Terashima, Miho; Fukuda, Hiromitsu; Saito, Izumu; Kanegae, Yumi
2007-06-01
The adenovirus vector is very attractive tool not only for the gene therapy but also for the basic sciences. However, because a construction method of this vector had been complex, only limited scientists had constructed and enjoyed the benefits. Recently, various methods were developed and the researchers came to be able to choose an efficient method, which is the COS-TPC method, or a concise procedure, which is the intact-genome transfection method (in vitro ligation method). Here we described not only these methods but also new method to construct the various Ads simultaneously using the recombinase-mediated cassette exchange (RMCE) by the site-specific recombinase. And also we want to refer the possibility to the worth of the vector, especially the vector of the expression-switch.
Vector resonances and electromagnetic nucleon structure
Robert Williams; Siegfried Krewald; Kevin Linen
1995-02-01
Motivated by new, precise magnetic proton form factor data in the timelike region, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson resonances on electromagnetic nucleon structure. We find that the rho (1700), omega (1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the pp-bar threshold. We also investigate sensitivity to the phi meson. The model dependence of our result is tested by introducing an alternative model which couples the isoscalar vector meson states to a hypothetical vector glueball resonance. We obtain nearly identical results from both models, except for GnE(q2) in the spacelike region which is very sensitive to the glueball mass and the effective phi NN coupling.
Vector Potential Generation for Numerical Relativity Simulations
NASA Astrophysics Data System (ADS)
Silberman, Zachary; Faber, Joshua; Adams, Thomas; Etienne, Zachariah; Ruchlin, Ian
2017-01-01
Many different numerical codes are employed in studies of highly relativistic magnetized accretion flows around black holes. Based on the formalisms each uses, some codes evolve the magnetic field vector B, while others evolve the magnetic vector potential A, the two being related by the curl: B=curl(A). Here, we discuss how to generate vector potentials corresponding to specified magnetic fields on staggered grids, a surprisingly difficult task on finite cubic domains. The code we have developed solves this problem in two ways: a brute-force method, whose scaling is nearly linear in the number of grid cells, and a direct linear algebra approach. We discuss the success both algorithms have in generating smooth vector potential configurations and how both may be extended to more complicated cases involving multiple mesh-refinement levels. NSF ACI-1550436
Insects as vectors: systematics and biology.
Rodhain, F
2015-04-01
Among the many complex relationships between insects and microorganisms such as viruses, bacteria and parasites, some have resulted in the establishment of biological systems within which the insects act as a biological vector for infectious agents. It is therefore advisable to understand the identity and biology of these vectors in depth, in order to define procedures for epidemiological surveillance and anti-vector control. The following are successively reviewed in this article: Anoplura (lice), Siphonaptera (fleas), Heteroptera (bugs: Cimicidae, Triatoma, Belostomatidae), Psychodidae (sandflies), Simuliidae (black flies), Ceratopogonidae (biting midges), Culicidae (mosquitoes), Tabanidae (horseflies) and Muscidae (tsetse flies, stable flies and pupipara). The authors provide a rapid overview of the morphology, systematics, development cycle and bio-ecology of each of these groups of vectors. Finally, their medical and veterinary importance is briefly reviewed.
Gamow vectors explain the shock profile.
Braidotti, Maria Chiara; Gentilini, Silvia; Conti, Claudio
2016-09-19
The description of shock waves beyond the shock point is a challenge in nonlinear physics and optics. Finding solutions to the global dynamics of dispersive shock waves is not always possible due to the lack of integrability. Here we propose a new method based on the eigenstates (Gamow vectors) of a reversed harmonic oscillator in a rigged Hilbert space. These vectors allow analytical formulation for the development of undular bores of shock waves in a nonlinear nonlocal medium. Experiments by a photothermal induced nonlinearity confirm theoretical predictions: the undulation period as a function of power and the characteristic quantized decays of Gamow vectors. Our results demonstrate that Gamow vectors are a novel and effective paradigm for describing extreme nonlinear phenomena.
VEST: Abstract vector calculus simplification in Mathematica
NASA Astrophysics Data System (ADS)
Squire, J.; Burby, J.; Qin, H.
2014-01-01
We present a new package, VEST (Vector Einstein Summation Tools), that performs abstract vector calculus computations in Mathematica. Through the use of index notation, VEST is able to reduce three-dimensional scalar and vector expressions of a very general type to a well defined standard form. In addition, utilizing properties of the Levi-Civita symbol, the program can derive types of multi-term vector identities that are not recognized by reduction, subsequently applying these to simplify large expressions. In a companion paper Burby et al. (2013) [12], we employ VEST in the automation of the calculation of high-order Lagrangians for the single particle guiding center system in plasma physics, a computation which illustrates its ability to handle very large expressions. VEST has been designed to be simple and intuitive to use, both for basic checking of work and more involved computations.
Imaging vector fields using Line Integral Convolution
Cabral, B.; Leedom, L.C.
1993-03-01
Imaging vector fields has applications in science, art, image processing and special effects. An effective new approach is to use linear and curvilinear filtering techniques to locally blur textures along a vector field. This approach builds on several previous texture generation and filtering techniques. It is, however, unique because it is local, one-dimensional and independent of any predefined geometry or texture. The technique is general and capable of imaging arbitrary two- and three-dimensional vector fields. The local one-dimensional nature of the algorithm lends itself to highly parallel and efficient implementations. Furthermore, the curvilinear filter is capable of rendering detail on very intricate vector fields. Combining this technique with other rendering and image processing techniques -- like periodic motion filtering -- results in richly informative and striking images. The technique can also produce novel special effects.
Vectorization of Monte Carlo particle transport
Burns, P.J.; Christon, M.; Schweitzer, R.; Lubeck, O.M.; Wasserman, H.J.; Simmons, M.L.; Pryor, D.V. . Computer Center; Los Alamos National Lab., NM; Supercomputing Research Center, Bowie, MD )
1989-01-01
Fully vectorized versions of the Los Alamos National Laboratory benchmark code Gamteb, a Monte Carlo photon transport algorithm, were developed for the Cyber 205/ETA-10 and Cray X-MP/Y-MP architectures. Single-processor performance measurements of the vector and scalar implementations were modeled in a modified Amdahl's Law that accounts for additional data motion in the vector code. The performance and implementation strategy of the vector codes are related to architectural features of each machine. Speedups between fifteen and eighteen for Cyber 205/ETA-10 architectures, and about nine for CRAY X-MP/Y-MP architectures are observed. The best single processor execution time for the problem was 0.33 seconds on the ETA-10G, and 0.42 seconds on the CRAY Y-MP. 32 refs., 12 figs., 1 tab.
Is addition of induction vectors meaningful?
NASA Astrophysics Data System (ADS)
Weaver, J. T.; Agarwal, A. K.
Justification is given for using the word 'vector' (with its mathematical implications) to describe the arrows first employed by Parkinson and Wiese to depict induced magnetic variation fields associated with conductivity anomalies. Despite this, caution should be exercised when trying to interpret physically the resultant obtained by adding or subtracting such vectors. Induction in a rectangular surface anomaly near a coastline is investigated numerically with the aid of a thin sheet program for inducing fields of periods 1 h and 20 min. It is found that in certain regions the induction vectors for this configuration are not given by the resultants of the separate induction vectors for the coastline and anomaly alone unless the anomaly is so far removed from the coastline that there is little electromagnetic coupling between them.
Electron-Vector Potential Interaction Hamiltonian
Ritchie, B
2003-03-27
The authors investigate an ambiguity inherent in the definition of the vector potential used in electron-electromagnetic field interactions. Two cases, Zeeman effect and Compton scattering, are studied.
Neural net approach to predictive vector quantization
NASA Astrophysics Data System (ADS)
Mohsenian, Nader; Nasrabadi, Nasser M.
1992-11-01
A new predictive vector quantization (PVQ) technique, capable of exploring the nonlinear dependencies in addition to the linear dependencies that exist between adjacent blocks of pixels, is introduced. Two different classes of neural nets form the components of the PVQ scheme. A multi-layer perceptron is embedded in the predictive component of the compression system. This neural network, using the non-linearity condition associated with its processing units, can perform as a non-linear vector predictor. The second component of the PVQ scheme vector quantizes (VQ) the residual vector that is formed by subtracting the output of the perceptron from the original wave-pattern. Kohonen Self-Organizing Feature Map (KSOFM) was utilized as a neural network clustering algorithm to design the codebook for the VQ technique. Coding results are presented for monochrome 'still' images.
Weaving Knotted Vector Fields with Tunable Helicity.
Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M
2016-12-30
We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.
The evolution of heart gene delivery vectors.
Wasala, Nalinda B; Shin, Jin-Hong; Duan, Dongsheng
2011-10-01
Gene therapy holds promise for treating numerous heart diseases. A key premise for the success of cardiac gene therapy is the development of powerful gene transfer vehicles that can achieve highly efficient and persistent gene transfer specifically in the heart. Other features of an ideal vector include negligible toxicity, minimal immunogenicity and easy manufacturing. Rapid progress in the fields of molecular biology and virology has offered great opportunities to engineer various genetic materials for heart gene delivery. Several nonviral vectors (e.g. naked plasmids, plasmid lipid/polymer complexes and oligonucleotides) have been tested. Commonly used viral vectors include lentivirus, adenovirus and adeno-associated virus. Among these, adeno-associated virus has shown many attractive features for pre-clinical experimentation in animal models of heart diseases. We review the history and evolution of these vectors for heart gene transfer. Copyright © 2011 John Wiley & Sons, Ltd.
Vector Analysis of Human Limb Motion.
ERIC Educational Resources Information Center
Laferriere, Joseph E.
1994-01-01
Uses vectors to illustrate movement of the human appendicular structures to help students visualize the interaction of the various muscles and understand how a small number of muscles can affect movement in a potentially infinite number of directions. (ZWH)
Viral vector-based influenza vaccines
de Vries, Rory D.; Rimmelzwaan, Guus F.
2016-01-01
ABSTRACT Antigenic drift of seasonal influenza viruses and the occasional introduction of influenza viruses of novel subtypes into the human population complicate the timely production of effective vaccines that antigenically match the virus strains that cause epidemic or pandemic outbreaks. The development of game-changing vaccines that induce broadly protective immunity against a wide variety of influenza viruses is an unmet need, in which recombinant viral vectors may provide. Use of viral vectors allows the delivery of any influenza virus antigen, or derivative thereof, to the immune system, resulting in the optimal induction of virus-specific B- and T-cell responses against this antigen of choice. This systematic review discusses results obtained with vectored influenza virus vaccines and advantages and disadvantages of the currently available viral vectors. PMID:27455345
Linear prediction of stationary vector sequences
NASA Technical Reports Server (NTRS)
Baram, Yoram
1988-01-01
The class of all linear predictors of minimal order for a stationary vector-valued process is specified in terms of linear transformations on the associated Hankel covariance matrix. Two particular transformations, yielding computationally efficient construction schemes, are proposed.
A Flexible Turbulent Vector Field Generator
NASA Astrophysics Data System (ADS)
Benassi, A.; Davis, A.
2004-12-01
Analysis and generation of turbulent vector fields is a necessity in many areas, such as Atmospheric Science. A candidate model of vector field must be flexible enough to tune some features, such as the spacial distribution of vortices, sinks and sources, according to physical measures. To achieve that goal, we propose a model that depends upon a given matricial function called "topolet" and a law of random vectors family. This model has a hierarchical structure. Its spinal column is a tree: the encoding tree of the domain where the vector field lives. The sets of vortices, sinks and sources are driven by some Bernouilli subtrees, directly giving their fractal dimension. At each node of the tree is attached a rate of energy loose giving the spectral slope. All those quantities are independantly identifiable on the base of mathematical proofs. A primitive version of this model have been proposed for generating clouds.
Measurements of Solar Vector Magnetic Fields
NASA Technical Reports Server (NTRS)
Hagyard, M. J. (Editor)
1985-01-01
Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display.
Ontology for Vector Surveillance and Management
LOZANO-FUENTES, SAUL; BANDYOPADHYAY, ARITRA; COWELL, LINDSAY G.; GOLDFAIN, ALBERT; EISEN, LARS
2013-01-01
Ontologies, which are made up by standardized and defined controlled vocabulary terms and their interrelationships, are comprehensive and readily searchable repositories for knowledge in a given domain. The Open Biomedical Ontologies (OBO) Foundry was initiated in 2001 with the aims of becoming an “umbrella” for life-science ontologies and promoting the use of ontology development best practices. A software application (OBO-Edit; *.obo file format) was developed to facilitate ontology development and editing. The OBO Foundry now comprises over 100 ontologies and candidate ontologies, including the NCBI organismal classification ontology (NCBITaxon), the Mosquito Insecticide Resistance Ontology (MIRO), the Infectious Disease Ontology (IDO), the IDOMAL malaria ontology, and ontologies for mosquito gross anatomy and tick gross anatomy. We previously developed a disease data management system for dengue and malaria control programs, which incorporated a set of information trees built upon ontological principles, including a “term tree” to promote the use of standardized terms. In the course of doing so, we realized that there were substantial gaps in existing ontologies with regards to concepts, processes, and, especially, physical entities (e.g., vector species, pathogen species, and vector surveillance and management equipment) in the domain of surveillance and management of vectors and vector-borne pathogens. We therefore produced an ontology for vector surveillance and management, focusing on arthropod vectors and vector-borne pathogens with relevance to humans or domestic animals, and with special emphasis on content to support operational activities through inclusion in databases, data management systems, or decision support systems. The Vector Surveillance and Management Ontology (VSMO) includes >2,200 unique terms, of which the vast majority (>80%) were newly generated during the development of this ontology. One core feature of the VSMO is the linkage
Ontology for vector surveillance and management.
Lozano-Fuentes, Saul; Bandyopadhyay, Aritra; Cowell, Lindsay G; Goldfain, Albert; Eisen, Lars
2013-01-01
Ontologies, which are made up by standardized and defined controlled vocabulary terms and their interrelationships, are comprehensive and readily searchable repositories for knowledge in a given domain. The Open Biomedical Ontologies (OBO) Foundry was initiated in 2001 with the aims of becoming an "umbrella" for life-science ontologies and promoting the use of ontology development best practices. A software application (OBO-Edit; *.obo file format) was developed to facilitate ontology development and editing. The OBO Foundry now comprises over 100 ontologies and candidate ontologies, including the NCBI organismal classification ontology (NCBITaxon), the Mosquito Insecticide Resistance Ontology (MIRO), the Infectious Disease Ontology (IDO), the IDOMAL malaria ontology, and ontologies for mosquito gross anatomy and tick gross anatomy. We previously developed a disease data management system for dengue and malaria control programs, which incorporated a set of information trees built upon ontological principles, including a "term tree" to promote the use of standardized terms. In the course of doing so, we realized that there were substantial gaps in existing ontologies with regards to concepts, processes, and, especially, physical entities (e.g., vector species, pathogen species, and vector surveillance and management equipment) in the domain of surveillance and management of vectors and vector-borne pathogens. We therefore produced an ontology for vector surveillance and management, focusing on arthropod vectors and vector-borne pathogens with relevance to humans or domestic animals, and with special emphasis on content to support operational activities through inclusion in databases, data management systems, or decision support systems. The Vector Surveillance and Management Ontology (VSMO) includes >2,200 unique terms, of which the vast majority (>80%) were newly generated during the development of this ontology. One core feature of the VSMO is the linkage, through
Chimpanzee Adenovirus Vector Ebola Vaccine.
Ledgerwood, Julie E; DeZure, Adam D; Stanley, Daphne A; Coates, Emily E; Novik, Laura; Enama, Mary E; Berkowitz, Nina M; Hu, Zonghui; Joshi, Gyan; Ploquin, Aurélie; Sitar, Sandra; Gordon, Ingelise J; Plummer, Sarah A; Holman, LaSonji A; Hendel, Cynthia S; Yamshchikov, Galina; Roman, Francois; Nicosia, Alfredo; Colloca, Stefano; Cortese, Riccardo; Bailer, Robert T; Schwartz, Richard M; Roederer, Mario; Mascola, John R; Koup, Richard A; Sullivan, Nancy J; Graham, Barney S
2017-03-09
The unprecedented 2014 epidemic of Ebola virus disease (EVD) prompted an international response to accelerate the availability of a preventive vaccine. A replication-defective recombinant chimpanzee adenovirus type 3-vectored ebolavirus vaccine (cAd3-EBO), encoding the glycoprotein from Zaire and Sudan species, that offers protection in the nonhuman primate model, was rapidly advanced into phase 1 clinical evaluation. We conducted a phase 1, dose-escalation, open-label trial of cAd3-EBO. Twenty healthy adults, in sequentially enrolled groups of 10 each, received vaccination intramuscularly in doses of 2×10(10) particle units or 2×10(11) particle units. Primary and secondary end points related to safety and immunogenicity were assessed throughout the first 8 weeks after vaccination; in addition, longer-term vaccine durability was assessed at 48 weeks after vaccination. In this small study, no safety concerns were identified; however, transient fever developed within 1 day after vaccination in two participants who had received the 2×10(11) particle-unit dose. Glycoprotein-specific antibodies were induced in all 20 participants; the titers were of greater magnitude in the group that received the 2×10(11) particle-unit dose than in the group that received the 2×10(10) particle-unit dose (geometric mean titer against the Zaire antigen at week 4, 2037 vs. 331; P=0.001). Glycoprotein-specific T-cell responses were more frequent among those who received the 2×10(11) particle-unit dose than among those who received the 2×10(10) particle-unit dose, with a CD4 response in 10 of 10 participants versus 3 of 10 participants (P=0.004) and a CD8 response in 7 of 10 participants versus 2 of 10 participants (P=0.07) at week 4. Assessment of the durability of the antibody response showed that titers remained high at week 48, with the highest titers in those who received the 2×10(11) particle-unit dose. Reactogenicity and immune responses to cAd3-EBO vaccine were dose
[Orthogonal Vector Projection Algorithm for Spectral Unmixing].
Song, Mei-ping; Xu, Xing-wei; Chang, Chein-I; An, Ju-bai; Yao, Li
2015-12-01
Spectrum unmixing is an important part of hyperspectral technologies, which is essential for material quantity analysis in hyperspectral imagery. Most linear unmixing algorithms require computations of matrix multiplication and matrix inversion or matrix determination. These are difficult for programming, especially hard for realization on hardware. At the same time, the computation costs of the algorithms increase significantly as the number of endmembers grows. Here, based on the traditional algorithm Orthogonal Subspace Projection, a new method called. Orthogonal Vector Projection is prompted using orthogonal principle. It simplifies this process by avoiding matrix multiplication and inversion. It firstly computes the final orthogonal vector via Gram-Schmidt process for each endmember spectrum. And then, these orthogonal vectors are used as projection vector for the pixel signature. The unconstrained abundance can be obtained directly by projecting the signature to the projection vectors, and computing the ratio of projected vector length and orthogonal vector length. Compared to the Orthogonal Subspace Projection and Least Squares Error algorithms, this method does not need matrix inversion, which is much computation costing and hard to implement on hardware. It just completes the orthogonalization process by repeated vector operations, easy for application on both parallel computation and hardware. The reasonability of the algorithm is proved by its relationship with Orthogonal Sub-space Projection and Least Squares Error algorithms. And its computational complexity is also compared with the other two algorithms', which is the lowest one. At last, the experimental results on synthetic image and real image are also provided, giving another evidence for effectiveness of the method.
Thrust Vectoring to Eliminate the Vertical Stabilizer
1979-12-01
THRUST VECTORING TO ELIMINATE THE VERTICAL STABILIZER THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of...qualities is shown to be 1 rad/sec. I i~ i 2i, THRUST VECTORING TO ELIMINATE THE VERTICAL STABILIZER I. Introduction There is increasing concern ove" he...the height of the cockpit will not help very much and would reduce the pilot’s visibility. Reduction of the size or elimination of the vertical
On the structure of Bethe vectors
NASA Astrophysics Data System (ADS)
Fuksa, J.
2017-07-01
The structure of Bethe vectors for generalised models associated with the rational and trigonometric R-matrix is investigated. The Bethe vectors in terms of two-component and multi-component models are described. Consequently, their structure in terms of local variables and operators is provided. This, as a consequence, proves the equivalence of coordinate and algebraic Bethe ansatzes for the Heisenberg spin chains. Hermitian conjugation of the elements of the monodromy matrix for the spin chains is studied.
Engineering HSV-1 vectors for gene therapy.
Goins, William F; Huang, Shaohua; Cohen, Justus B; Glorioso, Joseph C
2014-01-01
Virus vectors have been employed as gene transfer vehicles for various preclinical and clinical gene therapy applications, and with the approval of Glybera (alipogene tiparvovec) as the first gene therapy product as a standard medical treatment (Yla-Herttuala, Mol Ther 20: 1831-1832, 2013), gene therapy has reached the status of being a part of standard patient care. Replication-competent herpes simplex virus (HSV) vectors that replicate specifically in actively dividing tumor cells have been used in Phase I-III human trials in patients with glioblastoma multiforme, a fatal form of brain cancer, and in malignant melanoma. In fact, T-VEC (talimogene laherparepvec, formerly known as OncoVex GM-CSF) displayed efficacy in a recent Phase III trial when compared to standard GM-CSF treatment alone (Andtbacka et al. J Clin Oncol 31: sLBA9008, 2013) and may soon become the second FDA-approved gene therapy product used in standard patient care. In addition to the replication-competent oncolytic HSV vectors like T-VEC, replication-defective HSV vectors have been employed in Phase I-II human trials and have been explored as delivery vehicles for disorders such as pain, neuropathy, and other neurodegenerative conditions. Research during the last decade on the development of HSV vectors has resulted in the engineering of recombinant vectors that are totally replication defective, nontoxic, and capable of long-term transgene expression in neurons. This chapter describes methods for the construction of recombinant genomic HSV vectors based on the HSV-1 replication-defective vector backbones, steps in their purification, and their small-scale production for use in cell culture experiments as well as preclinical animal studies.
Vector Quantization With Emergent Codebook Structure
NASA Technical Reports Server (NTRS)
Ahalt, Stanley C.; Krishnamurthy, Ashok
1993-01-01
Proposed scheme under development for transmission of vector-quantized digital video images, vector quantizer codebook updated to adapt quantizer to changing signal statistics. Intended to be realized with electronic neural network. Codebook, which consists of patterns constituting video images, will undergo training during operation and scheme will develop codebooks ordered during training. System enables coding more compact, more immune to noise, and supports variable rate compression.
Visualization of Vector Field by Virtual Reality
NASA Astrophysics Data System (ADS)
Kageyama, A.; Tamura, Y.; Sato, T.
A visualization software program is developed in order to analyze three dimensional vector fields by means of today's advanced virtual reality technology. This program enables simulation researchers to interactively visualize stream lines, tracer particle motions, isosurfaces, etc.~with stereo view. The program accepts any kind of vector fields on structured mesh as an input data. A virtual reality hardware system, on which the program operates, and details of the program are described.
Vector resonances and electromagnetic nucleon structure
Williams, R.A.; Krewald, S.; Linen, K. )
1995-02-01
Motivated by new, precise magnetic proton form factor data in the timelike reigon, a hybrid vector meson dominance (hVMD) formalism is employed to investigate the significance of excited vector meson rsonances on electromagnetic nucleon structure. We find that the [rho](1700), [omega](1600), and two previously unobserved states are required to reproduce the local structure seen in the new LEAR data just above the [ital p[bar p
On estimating the Venus spin vector
NASA Technical Reports Server (NTRS)
Argentiero, P. D.
1972-01-01
The improvement in spin vector and probe position estimates one may reasonably expect from the processing of such data is indicated. This was done by duplicating the ensemble calculations associated with a weighed least squares with a priori estimation technique applied to range rate data that were assumed to be unbiased and uncorrelated. The weighting matrix was assumed to be the inverse of the covariance matrix of the noise on the data. Attention is focused primarily on the spin vector estimation.
Killing vector fields and harmonic superfield theories
Groeger, Josua
2014-09-15
The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.
Killing vector fields and harmonic superfield theories
NASA Astrophysics Data System (ADS)
Groeger, Josua
2014-09-01
The harmonic action functional allows a natural generalisation to semi-Riemannian supergeometry, also referred to as harmonic, which resembles the supersymmetric sigma models studied in high energy physics. We show that Killing vector fields are infinitesimal supersymmetries of this harmonic action and prove three different Noether theorems in this context. En passant, we provide a homogeneous treatment of five characterisations of Killing vector fields on semi-Riemannian supermanifolds, thus filling a gap in the literature.
Using multivalent adenoviral vectors for HIV vaccination.
Gu, Linlin; Li, Zan C; Krendelchtchikov, Alexandre; Krendelchtchikova, Valentina; Wu, Hongju; Matthews, Qiana L
2013-01-01
Adenoviral vectors have been used for a variety of vaccine applications including cancer and infectious diseases. Traditionally, Ad-based vaccines are designed to express antigens through transgene expression of a given antigen. For effective vaccine development it is often necessary to express or present multiple antigens to the immune system to elicit an optimal vaccine as observed preclinically with mosaic/polyvalent HIV vaccines or malaria vaccines. Due to the wide flexibility of Ad vectors they are an ideal platform for expressing large amounts of antigen and/or polyvalent mosaic antigens. Ad vectors that display antigens on their capsid surface can elicit a robust humoral immune response, the "antigen capsid-incorporation" strategy. The adenoviral hexon protein has been utilized to display peptides in the majority of vaccine strategies involving capsid incorporation. Based on our abilities to manipulate hexon HVR2 and HVR5, we sought to manipulate HVR1 in the context of HIV antigen display for the first time ever. More importantly, peptide incorporation within HVR1 was utilized in combination with other HVRs, thus creating multivalent vectors. To date this is the first report where dual antigens are displayed within one Ad hexon particle. These vectors utilize HVR1 as an incorporation site for a seven amino acid region of the HIV glycoprotein 41, in combination with six Histidine incorporation within HVR2 or HVR5. Our study illustrates that these multivalent antigen vectors are viable and can present HIV antigen as well as His6 within one Ad virion particle. Furthermore, mouse immunizations with these vectors demonstrate that these vectors can elicit a HIV and His6 epitope-specific humoral immune response.
Disease Vector Ecology Profile: Somalia. Fourth Edition
1993-09-15
filariasis, dengue, yellow fever, West Nile fever, onchocerciasis , louse-borne typhus, relapsing fever, soil-transmitted helminths, and a variety of...Transmitted by the bite of infected sand flies. For vector species, see Leishmaniasis. VECTOR BIONOMICS: See Leishmaniasis ONCHOCERCIASIS INFECTIOUS...Bull. Entomol. Res. 66(2): 345-63 (47 ref., 18 fig.). Raybould, J.N. & G.B. White. 1979. The distribution, bionomics and control of onchocerciasis
Efficient storage scheme and algorithms for w-matrix vector multiplication on vector computers
Huang, H.S.; Lu, C.N. . Dept. of Electrical Engineering)
1994-05-01
The W-matrix method has been proposed in many literatures to exploit parallelism in the solution of many power system problems. This paper presents a storage scheme for storing the sparse W-matrix in solving linear equations on vector computers. Based on the proposed storage scheme, several efficient algorithms have been developed to perform the W-matrix vector multiplication for finding linear system solution. In this paper, attention is given to the issues of vector length, data movement between vector registers and memory, and the vector stride. The proposed storage scheme and algorithms are tested on Convex 3840 and Alliant FX/80 vector machines. It is shown that a speedup of two to four times is obtainable as compared to traditional scalar operation. The proposed storage scheme and algorithms can be applied to power system problems that require repeat solutions of linear system, such as load flow, contingency analysis, fast decoupled state estimation and short circuit calculations.
Effects of Climate and Climate Change on Vectors and Vector-Borne Diseases: Ticks Are Different.
Ogden, Nick H; Lindsay, L Robbin
2016-08-01
There has been considerable debate as to whether global risk from vector-borne diseases will be impacted by climate change. This has focussed on important mosquito-borne diseases that are transmitted by the vectors from infected to uninfected humans. However, this debate has mostly ignored the biological diversity of vectors and vector-borne diseases. Here, we review how climate and climate change may impact those most divergent of arthropod disease vector groups: multivoltine insects and hard-bodied (ixodid) ticks. We contrast features of the life cycles and behaviour of these arthropods, and how weather, climate, and climate change may have very different impacts on the spatiotemporal occurrence and abundance of vectors, and the pathogens they transmit.
Lee, Dukhyung; Kim, Dai-Sik
2016-01-01
We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies. PMID:26740335
Vector analyses of linearly and circularly polarized Bessel beams using Hertz vector potentials.
Wang, Yanxun; Dou, Wenbin; Meng, Hongfu
2014-04-07
Using the transverse Hertz vector potentials, vector analyses of linearly and circularly polarized Bessel beams of arbitrary orders are presented in this paper. Expressions for the electric and magnetic fields of vector Bessel beams in free space that are rigorous solutions to the vector Helmholtz equation are derived. Their respective time averaged energy density and Poynting vector are also obtained, in order to exhibit their non-diffracting properties. Polarization patterns and magnitude profiles with different parameters are displayed. Particular emphasis is placed on the cases where the ratio of wave number over its transverse component k/kt approximately equals to one and largely exceeds it, which corresponding to the nonparaxial and paraxial condition, respectively. These results allow us to recognize that the vector Bessel beams exhibit new and important features, compared with the scalar fields.
Black holes in vector-tensor theories
NASA Astrophysics Data System (ADS)
Heisenberg, Lavinia; Kase, Ryotaro; Minamitsuji, Masato; Tsujikawa, Shinji
2017-08-01
We study static and spherically symmetric black hole (BH) solutions in second-order generalized Proca theories with nonminimal vector field derivative couplings to the Ricci scalar, the Einstein tensor, and the double dual Riemann tensor. We find concrete Lagrangians which give rise to exact BH solutions by imposing two conditions of the two identical metric components and the constant norm of the vector field. These exact solutions are described by either Reissner-Nordström (RN), stealth Schwarzschild, or extremal RN solutions with a non-trivial longitudinal mode of the vector field. We then numerically construct BH solutions without imposing these conditions. For cubic and quartic Lagrangians with power-law couplings which encompass vector Galileons as the specific cases, we show the existence of BH solutions with the difference between two non-trivial metric components. The quintic-order power-law couplings do not give rise to non-trivial BH solutions regular throughout the horizon exterior. The sixth-order and intrinsic vector-mode couplings can lead to BH solutions with a secondary hair. For all the solutions, the vector field is regular at least at the future or past horizon. The deviation from General Relativity induced by the Proca hair can be potentially tested by future measurements of gravitational waves in the nonlinear regime of gravity.
How random is a random vector?
Eliazar, Iddo
2015-12-15
Over 80 years ago Samuel Wilks proposed that the “generalized variance” of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the “Wilks standard deviation” –the square root of the generalized variance–is indeed the standard deviation of a random vector. We further establish that the “uncorrelation index” –a derivative of the Wilks standard deviation–is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: “randomness measures” and “independence indices” of random vectors. In turn, these general notions give rise to “randomness diagrams”—tangible planar visualizations that answer the question: How random is a random vector? The notion of “independence indices” yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.
Possible applications for replicating HIV 1 vectors
Das, Atze T; Jeeninga, Rienk E; Berkhout, Ben
2010-01-01
Since its discovery some 25 years ago, much has been learned about HIV type 1 and the molecular details of its replication cycle. This insight has been used to develop lentiviral vector systems that have advantages over conventional retroviral vector systems. For safety reasons, the lentiviral vector systems are replication incompetent and the risk of generating a replication competent virus has been minimized. Nevertheless, there may be certain applications for replication competent HIV based vector systems, and we will review our activities in this particular field. This includes the generation of a conditionally replicating HIV 1 variant as a safe live attenuated virus vaccine, the construction of mini HIV variants as cancer selective viruses for virotherapy against leukemia, and the use of a conditionally live anti HIV gene therapy vector. Although safety concerns will undoubtedly remain for the use of replication competent HIV based vector systems, some of the results in cell culture systems are very promising and warrant further testing in appropriate animal models. PMID:20582153
Possible applications for replicating HIV 1 vectors.
Das, Atze T; Jeeninga, Rienk E; Berkhout, Ben
2010-05-01
Since its discovery some 25 years ago, much has been learned about HIV type 1 and the molecular details of its replication cycle. This insight has been used to develop lentiviral vector systems that have advantages over conventional retroviral vector systems. For safety reasons, the lentiviral vector systems are replication incompetent and the risk of generating a replication competent virus has been minimized. Nevertheless, there may be certain applications for replication competent HIV based vector systems, and we will review our activities in this particular field. This includes the generation of a conditionally replicating HIV 1 variant as a safe live attenuated virus vaccine, the construction of mini HIV variants as cancer selective viruses for virotherapy against leukemia, and the use of a conditionally live anti HIV gene therapy vector. Although safety concerns will undoubtedly remain for the use of replication competent HIV based vector systems, some of the results in cell culture systems are very promising and warrant further testing in appropriate animal models.
Attitude Determination Using Two Vector Measurements
NASA Technical Reports Server (NTRS)
Markley, F. Landis
1998-01-01
Many spacecraft attitude determination methods use exactly two vector measurements. The two vectors are typically the unit vector to the Sun and the Earth's magnetic field vector for coarse "sun-mag" attitude determination or unit vectors to two stars tracked by two star trackers for fine attitude determination. TRIAD, the earliest published algorithm for determining spacecraft attitude from two vector measurements, has been widely used in both ground-based and onboard attitude determination. Later attitude determination methods have been based on Wahba's optimality criterion for n arbitrarily weighted observations. The solution of Wahba's problem is somewhat difficult in the general case, but there is a simple closed-form solution in the two-observation case. This solution reduces to the TRIAD solution for certain choices of measurement weights. This paper presents and compares these algorithms as well as sub-optimal algorithms proposed by Bar-Itzhack, Harman, and Reynolds. Some new results will be presented, but the paper is primarily a review and tutorial.
Feature Vector Construction Method for IRIS Recognition
NASA Astrophysics Data System (ADS)
Odinokikh, G.; Fartukov, A.; Korobkin, M.; Yoo, J.
2017-05-01
One of the basic stages of iris recognition pipeline is iris feature vector construction procedure. The procedure represents the extraction of iris texture information relevant to its subsequent comparison. Thorough investigation of feature vectors obtained from iris showed that not all the vector elements are equally relevant. There are two characteristics which determine the vector element utility: fragility and discriminability. Conventional iris feature extraction methods consider the concept of fragility as the feature vector instability without respect to the nature of such instability appearance. This work separates sources of the instability into natural and encodinginduced which helps deeply investigate each source of instability independently. According to the separation concept, a novel approach of iris feature vector construction is proposed. The approach consists of two steps: iris feature extraction using Gabor filtering with optimal parameters and quantization with separated preliminary optimized fragility thresholds. The proposed method has been tested on two different datasets of iris images captured under changing environmental conditions. The testing results show that the proposed method surpasses all the methods considered as a prior art by recognition accuracy on both datasets.
Multiclass Reduced-Set Support Vector Machines
NASA Technical Reports Server (NTRS)
Tang, Benyang; Mazzoni, Dominic
2006-01-01
There are well-established methods for reducing the number of support vectors in a trained binary support vector machine, often with minimal impact on accuracy. We show how reduced-set methods can be applied to multiclass SVMs made up of several binary SVMs, with significantly better results than reducing each binary SVM independently. Our approach is based on Burges' approach that constructs each reduced-set vector as the pre-image of a vector in kernel space, but we extend this by recomputing the SVM weights and bias optimally using the original SVM objective function. This leads to greater accuracy for a binary reduced-set SVM, and also allows vectors to be 'shared' between multiple binary SVMs for greater multiclass accuracy with fewer reduced-set vectors. We also propose computing pre-images using differential evolution, which we have found to be more robust than gradient descent alone. We show experimental results on a variety of problems and find that this new approach is consistently better than previous multiclass reduced-set methods, sometimes with a dramatic difference.
Virus-Vectored Influenza Virus Vaccines
Tripp, Ralph A.; Tompkins, S. Mark
2014-01-01
Despite the availability of an inactivated vaccine that has been licensed for >50 years, the influenza virus continues to cause morbidity and mortality worldwide. Constant evolution of circulating influenza virus strains and the emergence of new strains diminishes the effectiveness of annual vaccines that rely on a match with circulating influenza strains. Thus, there is a continued need for new, efficacious vaccines conferring cross-clade protection to avoid the need for biannual reformulation of seasonal influenza vaccines. Recombinant virus-vectored vaccines are an appealing alternative to classical inactivated vaccines because virus vectors enable native expression of influenza antigens, even from virulent influenza viruses, while expressed in the context of the vector that can improve immunogenicity. In addition, a vectored vaccine often enables delivery of the vaccine to sites of inductive immunity such as the respiratory tract enabling protection from influenza virus infection. Moreover, the ability to readily manipulate virus vectors to produce novel influenza vaccines may provide the quickest path toward a universal vaccine protecting against all influenza viruses. This review will discuss experimental virus-vectored vaccines for use in humans, comparing them to licensed vaccines and the hurdles faced for licensure of these next-generation influenza virus vaccines. PMID:25105278
Sindbis viral vectors target hematopoietic malignant cells.
Suzme, R; Tseng, J-C; Levin, B; Ibrahim, S; Meruelo, D; Pellicer, A
2012-11-01
Sindbis viral vectors target and inhibit the growth of various solid tumors in mouse models. However, their efficacy against blood cancer has not been well established. Here, we show that Sindbis vectors infect and efficiently trigger apoptosis in mouse BW5147 malignant hematopoietic T-cells, but only at low levels in human lymphoma and leukemia cells (Jurkat, Karpas, CEM, DHL and JB). The Mr 37/67 kD laminin receptor (LAMR) has been suggested to be the receptor for Sindbis virus. However, JB cells, which are infected by Sindbis at low efficiency, express high levels of LAMR, revealing that additional factors are involved in Sindbis tropism. To test the infectivity and therapeutic efficacy of Sindbis vectors against malignant hematopoietic cells in vivo, we injected BW5147 cells intraperitoneally into (C3HXAKR) F1 hybrid mice. We found that Sindbis vectors targeted the tumors and significantly prolonged survival of tumor-bearing mice. We also tested the Sindbis vectors in a transgenic CD4-Rgr model, which spontaneously develop thymic lymphomas. However, infectivity in this model was less efficient. Taken together, these results demonstrate that Sindbis vectors have the potential to target and kill hematopoietic malignancies in mice, but further research is needed to evaluate the mechanism underlining the susceptibility of human lymphoid malignancies to Sindbis therapy.
Blocking transmission of vector-borne diseases.
Schorderet-Weber, Sandra; Noack, Sandra; Selzer, Paul M; Kaminsky, Ronald
2017-04-01
Vector-borne diseases are responsible for significant health problems in humans, as well as in companion and farm animals. Killing the vectors with ectoparasitic drugs before they have the opportunity to pass on their pathogens could be the ideal way to prevent vector borne diseases. Blocking of transmission might work when transmission is delayed during blood meal, as often happens in ticks. The recently described systemic isoxazolines have been shown to successfully prevent disease transmission under conditions of delayed pathogen transfer. However, if the pathogen is transmitted immediately at bite as it is the case with most insects, blocking transmission becomes only possible if ectoparasiticides prevent the vector from landing on or, at least, from biting the host. Chemical entities exhibiting repellent activity in addition to fast killing, like pyrethroids, could prevent pathogen transmission even in cases of immediate transfer. Successful blocking depends on effective action in the context of the extremely diverse life-cycles of vectors and vector-borne pathogens of medical and veterinary importance which are summarized in this review. This complexity leads to important parameters to consider for ectoparasiticide research and when considering the ideal drug profile for preventing disease transmission.
Zhao, Henan; Bryant, Garnett W.; Griffin, Wesley; Terrill, Judith E.; Chen, Jian
2017-01-01
We designed and evaluated SplitVectors, a new vector field display approach to help scientists perform new discrimination tasks on large-magnitude-range scientific data shown in three-dimensional (3D) visualization environments. SplitVectors uses scientific notation to display vector magnitude, thus improving legibility. We present an empirical study comparing the SplitVectors approach with three other approaches - direct linear representation, logarithmic, and text display commonly used in scientific visualizations. Twenty participants performed three domain analysis tasks: reading numerical values (a discrimination task), finding the ratio between values (a discrimination task), and finding the larger of two vectors (a pattern detection task). Participants used both mono and stereo conditions. Our results suggest the following: (1) SplitVectors improve accuracy by about 10 times compared to linear mapping and by four times to logarithmic in discrimination tasks; (2) SplitVectors have no significant differences from the textual display approach, but reduce cluttering in the scene; (3) SplitVectors and textual display are less sensitive to data scale than linear and logarithmic approaches; (4) using logarithmic can be problematic as participants' confidence was as high as directly reading from the textual display, but their accuracy was poor; and (5) Stereoscopy improved performance, especially in more challenging discrimination tasks. PMID:28113469
Henan Zhao; Bryant, Garnett W; Griffin, Wesley; Terrill, Judith E; Jian Chen
2017-06-01
We designed and evaluated SplitVectors, a new vector field display approach to help scientists perform new discrimination tasks on large-magnitude-range scientific data shown in three-dimensional (3D) visualization environments. SplitVectors uses scientific notation to display vector magnitude, thus improving legibility. We present an empirical study comparing the SplitVectors approach with three other approaches - direct linear representation, logarithmic, and text display commonly used in scientific visualizations. Twenty participants performed three domain analysis tasks: reading numerical values (a discrimination task), finding the ratio between values (a discrimination task), and finding the larger of two vectors (a pattern detection task). Participants used both mono and stereo conditions. Our results suggest the following: (1) SplitVectors improve accuracy by about 10 times compared to linear mapping and by four times to logarithmic in discrimination tasks; (2) SplitVectors have no significant differences from the textual display approach, but reduce cluttering in the scene; (3) SplitVectors and textual display are less sensitive to data scale than linear and logarithmic approaches; (4) using logarithmic can be problematic as participants' confidence was as high as directly reading from the textual display, but their accuracy was poor; and (5) Stereoscopy improved performance, especially in more challenging discrimination tasks.
Viral Vectors for in Vivo Gene Transfer
NASA Astrophysics Data System (ADS)
Thévenot, E.; Dufour, N.; Déglon, N.
The transfer of DNA into the nucleus of a eukaryotic cell (gene transfer) is a central theme of modern biology. The transfer is said to be somatic when it refers to non-germline organs of a developed individual, and germline when it concerns gametes or the fertilised egg of an animal, with the aim of transmitting the relevant genetic modification to its descendents [1]. The efficient introduction of genetic material into a somatic or germline cell and the control of its expression over time have led to major advances in understanding how genes work in vivo, i.e., in living organisms (functional genomics), but also to the development of innovative therapeutic methods (gene therapy). The efficiency of gene transfer is conditioned by the vehicle used, called the vector. Desirable features for a vector are as follows: Easy to produce high titer stocks of the vector in a reproducible way. Absence of toxicity related to transduction (transfer of genetic material into the target cell, and its expression there) and no immune reaction of the organism against the vector and/or therapeutic protein. Stability in the expression of the relevant gene over time, and the possibility of regulation, e.g., to control expression of the therapeutic protein on the physiological level, or to end expression at the end of treatment. Transduction of quiescent cells should be as efficient as transduction of dividing cells. Vectors currently used fall into two categories: non-viral and viral vectors. In non-viral vectors, the DNA is complexed with polymers, lipids, or cationic detergents (described in Chap. 3). These vectors have a low risk of toxicity and immune reaction. However, they are less efficient in vivo than viral vectors when it comes to the number of cells transduced and long-term transgene expression. (Naked DNA transfer or electroporation is rather inefficient in the organism. This type of gene transfer will not be discussed here, and the interested reader is referred to the
Modified montmorillonite as vector for gene delivery.
Lin, Feng-Huei; Chen, Chia-Hao; Cheng, Winston T K; Kuo, Tzang-Fu
2006-06-01
Currently, gene delivery systems can be divided into two parts: viral or non-viral vectors. In general, viral vectors have a higher efficiency on gene delivery. However, they may sometimes provoke mutagenesis and carcinogenesis once re-activating in human body. Lots of non-viral vectors have been developed that tried to solve the problems happened on viral vectors. Unfortunately, most of non-viral vectors showed relatively lower transfection rate. The aim of this study is to develop a non-viral vector for gene delivery system. Montmorillonite (MMT) is one of clay minerals that consist of hydrated aluminum with Si-O tetrahedrons on the bottom of the layer and Al-O(OH)2 octahedrons on the top. The inter-layer space is about 12 A. The room is not enough to accommodate DNA for gene delivery. In the study, the cationic hexadecyltrimethylammonium (HDTMA) will be intercalated into the interlayer of MMT as a layer expander to expand the layer space for DNA accommodation. The optimal condition for the preparation of DNA-HDTMA-MMT is as follows: 1 mg of 1.5CEC HDTMA-MMT was prepared under pH value of 10.7 and with soaking time for 2 h. The DNA molecules can be protected from nuclease degradation, which can be proven by the electrophoresis analysis. DNA was successfully transfected into the nucleus of human dermal fibroblast and expressed enhanced green fluorescent protein (EGFP) gene with green fluorescence emission. The HDTMA-MMT has a great potential as a vector for gene delivery in the future.
Stevens, L; Rizzo, D M; Lucero, D E; Pizarro, J C
2013-07-01
ABSTRACT Disease transmission is difficult to model because most vectors and hosts have different generation times. Chagas disease is such a situation, where insect vectors have 1-2 generations annually and mammalian hosts, including humans, can live for decades. The hemataphagous triatominae vectors (Hemiptera: Reduviidae) of the causative parasite Trypanosoma cruzi (Kinetoplastida: Trypanosomatidae) usually feed on sleeping hosts, making vector infestation of houses, peridomestic areas, and wild animal burrows a central factor in transmission. Because of difficulties with different generation times, we developed a model considering the dwelling as the unit of infection, changing the dynamics from an indirect to a direct transmission model. In some regions, vectors only infest houses; in others, they infest corrals; and in some regions, they also infest wild animal burrows. We examined the effect of sylvatic and peridomestic vector populations on household infestation rates. Both sylvatic and peridomestic vectors increase house infestation rates, sylvatic much more than peridomestic, as measured by the reproductive number R0. The efficacy of manipulating parameters in the model to control vector populations was examined. When R0 > 1, the number of infested houses increases. The presence of sylvatic vectors increases R0 by at least an order of magnitude. When there are no sylvatic vectors, spraying rate is the most influential parameter. Spraying rate is relatively unimportant when there are sylvatic vectors; in this case, community size, especially the ratio of houses to sylvatic burrows, is most important. The application of this modeling approach to other parasites and enhancements of the model are discussed.
New Constitutive Vectors: Useful Genetic Engineering Tools for Biocatalysis
Xu, Youqiang; Tao, Fei; Xu, Ping
2013-01-01
Constitutive vectors are useful tools for genetic engineering. Two constitutive vectors with high levels of expression and broad host ranges were developed and used in a range of Pseudomonas hosts. The vectors showed superior characteristics compared to the inducible vectors as well as the potential to be used as improved genetic tools for biocatalysis. PMID:23416993
40 CFR 503.33 - Vector attraction reduction.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Vector attraction reduction. 503.33... STANDARDS FOR THE USE OR DISPOSAL OF SEWAGE SLUDGE Pathogens and Vector Attraction Reduction § 503.33 Vector attraction reduction. (a)(1) One of the vector attraction reduction requirements in § 503.33 (b)(1)...
New constitutive vectors: useful genetic engineering tools for biocatalysis.
Xu, Youqiang; Tao, Fei; Ma, Cuiqing; Xu, Ping
2013-04-01
Constitutive vectors are useful tools for genetic engineering. Two constitutive vectors with high levels of expression and broad host ranges were developed and used in a range of Pseudomonas hosts. The vectors showed superior characteristics compared to the inducible vectors as well as the potential to be used as improved genetic tools for biocatalysis.
Malaria vector species in Colombia - A review
Montoya-Lerma, James; Solarte, Yezid A; Giraldo-Calderón, Gloria Isabel; Quiñones, Martha L; Ruiz-López, Freddy; Wilkerson, Richard C; González, Ranulfo
2016-01-01
Here we present a comprehensive review of the literature on the vectorial importance of the major Anopheles malaria vectors in Colombia. We provide basic information on the geographical distribution, altitudinal range, immature habitats, adult behaviour, feeding preferences and anthropophily, endophily and infectivity rates. We additionally review information on the life cycle, longevity and population fluctuation of Colombian Anopheles species. Emphasis was placed on the primary vectors that have been epidemiologically incriminated in malaria transmission: Anopheles darlingi, Anopheles albimanus and Anopheles nuneztovari. The role of a selection of local, regional or secondary vectors (e.g., Anopheles pseudopunctipennis and Anopheles neivai) is also discussed. We highlight the importance of combining biological, morphological and molecular data for the correct taxonomical determination of a given species, particularly for members of the species complexes. We likewise emphasise the importance of studying the bionomics of primary and secondary vectors along with an examination of the local conditions affecting the transmission of malaria. The presence and spread of the major vectors and the emergence of secondary species capable of transmitting human Plasmodia are of great interest. When selecting control measures, the anopheline diversity in the region must be considered. Variation in macroclimate conditions over a species’ geographical range must be well understood and targeted to plan effective control measures based on the population dynamics of the local Anopheles species. PMID:21881778
A comparison of in situ measurements of vector-E and - vector-V x vector-B from Dynamics Explorer 2
NASA Technical Reports Server (NTRS)
Hanson, W. B.; Coley, W. R.; Heelis, R. A.; Maynard, N. C.; Aggson, T. L.
1993-01-01
Dynamics Explorer-2 provided the first opportunity to make a direct comparison of in situ measurements of the high-latitude convection electric field by two distinctly different techniques. The vector electric field instrument (VEFI) used antennae to measure the intrinsic electric fields and the ion drift meter (IDM) and retarding potential analyzer (RPA) measured the ion drift velocity vector, from which the convection electric field can be deduced. The data from three orbits having large electric fields at high latitude are presented, one at high, one at medium, and one at low altitudes. The general agreement between the two measurements of electric field is very good, with typical differences at high latitudes of the order of a few millivolts per meter, but there are some regions where the particle fluxes are extremely large (e.g., the cusp) and the disagreement is worse, probably because of IDM difficulties. The auroral zone potential patterns derived from the two devices are in excellent agreement for two of the cases, but not in the third, where bad attitude data may be the problem. At low latitudes there are persistent differences in the measurements of a few millivolts per meter, though these differences are quite constant from orbit to orbit. This problem seems to arise from some shortcoming in the VEFI measurments. Overall, however, these measurements confirm the concept of `frozen-in' plasma that drifts with velocity vector-E x vector-B/B(exp 2) within the measurement errors of the two techniques.
[Lipid vectors. New strategies for gene therapy].
Romero, E L; Morilla, M J; Bakas, L S
2001-01-01
Phospholipids are capable of spontaneous self-assembling, a remarkable differential property if compared with the rest of biological molecules. By their means it is relatively easy to generate extremely stable sealed structures, with controlled shape, size and packing, known as liposomes. In this article, we review the use of liposomes to improve the transfection process in eucaryotic cells, in vitro as well as in vivo. By employing lipid vectors, it is feasible to selectively transport a DNA segment to any target of the body, to force it to enter a cell and once inside it, to exert a control on its ultimate intracellular fate. The goal of lipid vectors to successfully transfect a cell in vivo, lies on the provision of a mechanical protection for DNA against plasma degradation, together with the possibility of controlling DNA biodistribution, independently of its size and sequence. Moreover, lipid vectors are not carcinogenic and are poorly immunogenic. Current challenge in lipid synthesis allows for a vector design which should be efficient enough to compete with high transfection levels of a viral vector, but with the extreme versatility, simplicity and biosafety characteristic of self assembling molecules.
Affine conformal vectors in space-time
NASA Astrophysics Data System (ADS)
Coley, A. A.; Tupper, B. O. J.
1992-05-01
All space-times admitting a proper affine conformal vector (ACV) are found. By using a theorem of Hall and da Costa, it is shown that such space-times either (i) admit a covariantly constant vector (timelike, spacelike, or null) and the ACV is the sum of a proper affine vector and a conformal Killing vector or (ii) the space-time is 2+2 decomposable, in which case it is shown that no ACV can exist (unless the space-time decomposes further). Furthermore, it is proved that all space-times admitting an ACV and a null covariantly constant vector (which are necessarily generalized pp-wave space-times) must have Ricci tensor of Segré type {2,(1,1)}. It follows that, among space-times admitting proper ACV, the Einstein static universe is the only perfect fluid space-time, there are no non-null Einstein-Maxwell space-times, and only the pp-wave space-times are representative of null Einstein-Maxwell solutions. Otherwise, the space-times can represent anisotropic fluids and viscous heat-conducting fluids, but only with restricted equations of state in each case.
Stability of Horndeski vector-tensor interactions
Jiménez, Jose Beltrán; Durrer, Ruth; Heisenberg, Lavinia; Thorsrud, Mikjel E-mail: ruth.durrer@unige.ch E-mail: mikjel.thorsrud@astro.uio.no
2013-10-01
We study the Horndeski vector-tensor theory that leads to second order equations of motion and contains a non-minimally coupled abelian gauge vector field. This theory is remarkably simple and consists of only 2 terms for the vector field, namely: the standard Maxwell kinetic term and a coupling to the dual Riemann tensor. Furthermore, the vector sector respects the U(1) gauge symmetry and the theory contains only one free parameter, M{sup 2}, that controls the strength of the non-minimal coupling. We explore the theory in a de Sitter spacetime and study the presence of instabilities and show that it corresponds to an attractor solution in the presence of the vector field. We also investigate the cosmological evolution and stability of perturbations in a general FLRW spacetime. We find that a sufficient condition for the absence of ghosts is M{sup 2} > 0. Moreover, we study further constraints coming from imposing the absence of Laplacian instabilities. Finally, we study the stability of the theory in static and spherically symmetric backgrounds (in particular, Schwarzschild and Reissner-Nordström-de Sitter). We find that the theory, quite generally, do have ghosts or Laplacian instabilities in regions of spacetime where the non-minimal interaction dominates over the Maxwell term. We also calculate the propagation speed in these spacetimes and show that superluminality is a quite generic phenomenon in this theory.
Measurement of Charmless B to Vector-Vector decays at BaBar
Olaiya, Emmanuel; /Rutherford
2011-11-14
The authors present results of B {yields} vector-vector (VV) and B {yields} vector-axial vector (VA) decays B{sup 0} {yields} {phi}X(X = {phi},{rho}{sup +} or {rho}{sup 0}), B{sup +} {yields} {phi}K{sup (*)+}, B{sup 0} {yields} K*K*, B{sup 0} {yields} {rho}{sup +}b{sub 1}{sup -} and B{sup +} {yields} K*{sup 0}{alpha}{sub 1}{sup +}. The largest dataset used for these results is based on 465 x 10{sup 6} {Upsilon}(4S) {yields} B{bar B} decays, collected with the BABAR detector at the PEP-II B meson factory located at the Stanford Linear Accelerator Center (SLAC). Using larger datasets, the BABAR experiment has provided more precise B {yields} VV measurements, further supporting the smaller than expected longitudinal polarization fraction of B {yields} {phi}K*. Additional B meson to vector-vector and vector-axial vector decays have also been studied with a view to shedding light on the polarization anomaly. Taking into account the available errors, we find no disagreement between theory and experiment for these additional decays.
Test of Understanding of Vectors: A Reliable Multiple-Choice Vector Concept Test
ERIC Educational Resources Information Center
Barniol, Pablo; Zavala, Genaro
2014-01-01
In this article we discuss the findings of our research on students' understanding of vector concepts in problems without physical context. First, we develop a complete taxonomy of the most frequent errors made by university students when learning vector concepts. This study is based on the results of several test administrations of open-ended…
Test of Understanding of Vectors: A Reliable Multiple-Choice Vector Concept Test
ERIC Educational Resources Information Center
Barniol, Pablo; Zavala, Genaro
2014-01-01
In this article we discuss the findings of our research on students' understanding of vector concepts in problems without physical context. First, we develop a complete taxonomy of the most frequent errors made by university students when learning vector concepts. This study is based on the results of several test administrations of open-ended…
Reduced Order Model Basis Vector Generation: Generates Basis Vectors fro ROMs
Arrighi, Bill
2016-03-03
libROM is a library that implements order reduction via singular value decomposition (SVD) of sampled state vectors. It implements 2 parallel, incremental SVD algorithms and one serial, non-incremental algorithm. It also provides a mechanism for adaptive sampling of basis vectors.
Gay, Virginie; Moreau, Karen; Hong, Saw-See; Ronfort, Corinne
2012-02-01
A human immunodeficiency virus type (HIV-1)-based lentiviral vector pseudotyped with the vesicular stomatitis virus envelope glycoprotein and encoding the GFP reporter gene was used to evaluate different methods of lentiviral vector titration. GFP expression, viral DNA quantification and the efficiency of vector DNA integration were assayed after infection of conventional HIV-1-permissive cell lines and human primary adult fibroblasts with the vector. We found that vector titers based on GFP expression determined by flow cytometry may vary by more than 50-fold depending on the cell type and the promoter-cell combination used. Interestingly, we observed that the viral integration process in primary HDFa cells was significantly more efficient compared to that in SupT1 or 293T cells. We propose that determination of the amount of integrated viral DNA by quantitative PCR be used in combination with the reporter gene expression assay.
A viral protease relocalizes in the presence of the vector to promote vector performance
Bak, Aurélie; Cheung, Andrea L.; Yang, Chunling; Whitham, Steven A.; Casteel, Clare L.
2017-01-01
Vector-borne pathogens influence host characteristics relevant to host–vector contact, increasing pathogen transmission and survival. Previously, we demonstrated that infection with Turnip mosaic virus, a member of one of the largest families of plant-infecting viruses, increases vector attraction and reproduction on infected hosts. These changes were due to a single viral protein, NIa-Pro. Here we show that NIa-Pro responds to the presence of the aphid vector during infection by relocalizing to the vacuole. Remarkably, vacuolar localization is required for NIa-Pro's ability to enhance aphid reproduction on host plants, vacuole localization disappears when aphids are removed, and this phenomenon occurs for another potyvirus, Potato virus Y, suggesting a conserved role for the protein in vector–host interactions. Taken together, these results suggest that potyviruses dynamically respond to the presence of their vectors, promoting insect performance and transmission only when needed. PMID:28205516
Vector systems for prenatal gene therapy: principles of non-viral vector design and production.
Wong, Suet Ping; Argyros, Orestis; Harbottle, Richard P
2012-01-01
Gene therapy vectors based on viruses are the most effective gene delivery systems in use today and although efficient at gene transfer their potential toxicity (Hacein-Bey-Abina et al., Science 302:415-419, 2003) provides impetus for the development of safer non-viral alternatives. An ideal vector for human gene therapy should deliver sustainable therapeutic levels of gene expression without affecting the viability of the host at either the cellular or somatic level. Vectors, which comprise entirely human elements, may provide the most suitable method of achieving this. Non-viral vectors are attractive alternatives to viral gene delivery systems because of their low toxicity, relatively easy production, and great versatility. The development of more efficient, economically prepared, and safer gene delivery vectors is a crucial prerequisite for their successful clinical application and remains a primary strategic task of gene therapy research.
González, C R; Reyes, C; Canals, A; Parra, A; Muñoz, X; Rodríguez, K
2015-12-01
Four species of triatomines are known from Chile: Triatoma infestans Klug, Mepraia spinolai Porter, M. gajardoi Frías, Henry & González, and M. parapatrica Frías (Hemiptera: Reduviidae), the last three are endemic. The geographical distribution of M. gajardoi includes the coastal areas in the north of Chile between 18° and 21°S, an area with both a resident workforce and summer-season visitors. A study was developed to assess the risk of vectorial transmission of Chagas disease by M. gajardoi in hut settlements on the coast of the Tarapacá Region, in particular in Caleta San Marcos and Caleta Río Seco. The study comprised fingerstick sampling of 95 persons, venous samples from 29 domestic dogs and capture of 52 triatomines, from both fishing coves. The samples were analysed by enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) techniques. The results show that, of the total number of persons studied, 100% were negative for Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae) antibodies, 10.34% of canids were positive for the antibody and 5.8% of M. gajardoi were infected to the PCR technique. The presence of this species in areas close to human settlements constitutes a risk to human populations established on the coast of northern Chile.
Pita, Sebastián; Panzera, Francisco; Sánchez, Antonio; Palomeque, Teresa; Lorite, Pedro
2016-09-29
In order to provide a broad picture on the origin and evolution of holocentric X chromosomes in heteropteran species, we prepared a sex chromosome painting probe by microdissection of the X1 and X2 chromosomes from a kissing bug Mepraia spinolai (Hemiptera: Reduviidae: Triatominae). Fluorescence in situ hybridization on four species of the Triatomini having different amounts of autosomal heterochromatin and sex chromosome systems show that the Xs probe hybridizes on the euchromatin, located both on autosomes and X chromosomes. The heterochromatic Y chromosome and autosomal heterochromatic regions always appear free of hybridization signals. The hybridization results of the Xs probe on Rhodnius prolixus (Rhodniini) is completely different to that observed in Triatomini species. The hybridization signals are small and scattered on all euchromatin, without specific regions including the X chromosome. These results are in accordance with previous data obtained by genomic in situ hybridization and fluorescent banding, suggesting a clear differentiation in the repeat sequence composition of both sex chromosomes between Triatomini and Rhodniini tribes. These results also support that each sex chromosome in Triatomini has evolved independently from different autosomal pairs of a common ancestor, as described in other insect orders. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Pita, Sebastián; Panzera, Francisco; Sánchez, Antonio; Palomeque, Teresa; Lorite, Pedro
2017-01-01
In order to provide a broad picture on the origin and evolution of holocentric X chromosomes in heteropteran species, we prepared a sex chromosome painting probe by microdissection of the X1 and X2 chromosomes from a kissing bug Mepraia spinolai (Hemiptera: Reduviidae: Triatominae). Fluorescence in situ hybridization on four species of the Triatomini having different amounts of autosomal heterochromatin and sex chromosome systems show that the Xs probe hybridizes on the euchromatin, located both on autosomes and X chromosomes. The heterochromatic Y chromosome and autosomal heterochromatic regions always appear free of hybridization signals. The hybridization results of the Xs probe on Rhodnius prolixus (Rhodniini) is completely different to that observed in Triatomini species. The hybridization signals are small and scattered on all euchromatin, without specific regions including the X chromosome. These results are in accordance with previous data obtained by genomic in situ hybridization and fluorescent banding, suggesting a clear differentiation in the repeat sequence composition of both sex chromosomes between Triatomini and Rhodniini tribes. These results also support that each sex chromosome in Triatomini has evolved independently from different autosomal pairs of a common ancestor, as described in other insect orders. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Emergence and prevalence of human vector-borne diseases in sink vector populations.
Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien
2012-01-01
Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining 'source' populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining 'sink' vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15-55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale.
Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations
Rascalou, Guilhem; Pontier, Dominique; Menu, Frédéric; Gourbière, Sébastien
2012-01-01
Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining ‘source’ populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining ‘sink’ vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15–55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale. PMID:22629337
Viral vectors: from virology to transgene expression
Bouard, D; Alazard-Dany, N; Cosset, F-L
2009-01-01
In the late 1970s, it was predicted that gene therapy would be applied to humans within a decade. However, despite some success, gene therapy has still not become a routine practise in medicine. In this review, we will examine the problems, both experimental and clinical, associated with the use of viral material for transgenic insertion. We shall also discuss the development of viral vectors involving the most important vector types derived from retroviruses, adenoviruses, herpes simplex viruses and adeno-associated viruses. This article is part of a themed section on Vector Design and Drug Delivery. For a list of all articles in this section see the end of this paper, or visit: http://www3.interscience.wiley.com/journal/121548564/issueyear?year=2009 PMID:18776913
Rickettsial pathogens and their arthropod vectors.
Azad, A. F.; Beard, C. B.
1998-01-01
Rickettsial diseases, important causes of illness and death worldwide, exist primarily in endemic and enzootic foci that occasionally give rise to sporadic or seasonal outbreaks. Rickettsial pathogens are highly specialized for obligate intracellular survival in both the vertebrate host and the invertebrate vector. While studies often focus primarily on the vertebrate host, the arthropod vector is often more important in the natural maintenance of the pathogen. Consequently, coevolution of rickettsiae with arthropods is responsible for many features of the host-pathogen relationship that are unique among arthropod-borne diseases, including efficient pathogen replication, long-term maintenance of infection, and transstadial and transovarial transmission. This article examines the common features of the host-pathogen relationship and of the arthropod vectors of the typhus and spotted fever group rickettsiae. PMID:9621188
The optical analogy for vector fields
NASA Technical Reports Server (NTRS)
Parker, E. N. (Editor)
1991-01-01
This paper develops the optical analogy for a general vector field. The optical analogy allows the examination of certain aspects of a vector field that are not otherwise readily accessible. In particular, in the cases of a stationary Eulerian flow v of an ideal fluid and a magnetostatic field B, the vectors v and B have surface loci in common with their curls. The intrinsic discontinuities around local maxima in absolute values of v and B take the form of vortex sheets and current sheets, respectively, the former playing a fundamental role in the development of hydrodyamic turbulence and the latter playing a major role in heating the X-ray coronas of stars and galaxies.
Replicon RNA Viral Vectors as Vaccines
Lundstrom, Kenneth
2016-01-01
Single-stranded RNA viruses of both positive and negative polarity have been used as vectors for vaccine development. In this context, alphaviruses, flaviviruses, measles virus and rhabdoviruses have been engineered for expression of surface protein genes and antigens. Administration of replicon RNA vectors has resulted in strong immune responses and generation of neutralizing antibodies in various animal models. Immunization of mice, chicken, pigs and primates with virus-like particles, naked RNA or layered DNA/RNA plasmids has provided protection against challenges with lethal doses of infectious agents and administered tumor cells. Both prophylactic and therapeutic efficacy has been achieved in cancer immunotherapy. Moreover, recombinant particles and replicon RNAs have been encapsulated by liposomes to improve delivery and targeting. Replicon RNA vectors have also been subjected to clinical trials. Overall, immunization with self-replicating RNA viruses provides high transient expression levels of antigens resulting in generation of neutralizing antibody responses and protection against lethal challenges under safe conditions. PMID:27827980
Covariant Lyapunov vectors for rigid disk systems.
Bosetti, Hadrien; Posch, Harald A
2010-10-05
We carry out extensive computer simulations to study the Lyapunov instability of a two-dimensional hard-disk system in a rectangular box with periodic boundary conditions. The system is large enough to allow the formation of Lyapunov modes parallel to the x-axis of the box. The Oseledec splitting into covariant subspaces of the tangent space is considered by computing the full set of covariant perturbation vectors co-moving with the flow in tangent space. These vectors are shown to be transversal, but generally not orthogonal to each other. Only the angle between covariant vectors associated with immediate adjacent Lyapunov exponents in the Lyapunov spectrum may become small, but the probability of this angle to vanish approaches zero. The stable and unstable manifolds are transverse to each other and the system is hyperbolic.
Thrust vectoring for lateral-directional stability
NASA Technical Reports Server (NTRS)
Peron, Lee R.; Carpenter, Thomas
1992-01-01
The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by using the Aerodynamic Preliminary Analysis System II panel code. The resulting lateral-directional linear perturbation analysis of a modified F-16 aircraft with various tail sizes and yaw vectoring was performed at several speeds and altitudes to determine the stability and control trends for the aircraft compared to these trends for a baseline aircraft. A study of the paddle-type turning vane thrust vectoring control system as used on the National Aeronautics and Space Administration F/A-18 High Alpha Research Vehicle is also presented.
Molecular Epidemiology for Vector Research on Leishmaniasis
Kato, Hirotomo; Gomez, Eduardo A; Cáceres, Abraham G; Uezato, Hiroshi; Mimori, Tatsuyuki; Hashiguchi, Yoshihisa
2010-01-01
Leishmaniasis is a protozoan disease caused by the genus Leishmania transmitted by female phlebotomine sand flies. Surveillance of the prevalence of Leishmania and responsive vector species in endemic and surrounding areas is important for predicting the risk and expansion of the disease. Molecular biological methods are now widely applied to epidemiological studies of infectious diseases including leishmaniasis. These techniques are used to detect natural infections of sand fly vectors with Leishmania protozoa and are becoming powerful tools due to their sensitivity and specificity. Recently, genetic analyses have been performed on sand fly species and genotyping using PCR-RFLP has been applied to the sand fly taxonomy. In addition, a molecular mass screening method has been established that enables both sand fly species and natural leishmanial infections to be identified simultaneously in hundreds of sand flies with limited effort. This paper reviews recent advances in the study of sand flies, vectors of leishmaniasis, using molecular biological approaches. PMID:20617005
Weyl node with random vector potential
NASA Astrophysics Data System (ADS)
Sbierski, Björn; Decker, Kevin S. C.; Brouwer, Piet W.
2016-12-01
We study Weyl semimetals in the presence of generic disorder, consisting of a random vector potential as well as a random scalar potential. We derive renormalization group flow equations to second order in the disorder strength. These flow equations predict a disorder-induced phase transition between a pseudoballistic weak-disorder phase and a diffusive strong-disorder phase for a sufficiently strong random scalar potential or for a pure three-component random vector potential. We verify these predictions using a numerical study of the density of states near the Weyl point and of quantum transport properties at the Weyl point. In contrast, for a pure single-component random vector potential, the diffusive strong-disorder phase is absent.
Novel signatures for vector-like quarks
NASA Astrophysics Data System (ADS)
Aguilar-Saavedra, J. A.; López-Fogliani, D. E.; Muñoz, C.
2017-06-01
We consider supersymmetric extensions of the standard model with a vector-like doublet ( T B) of quarks with charge 2 /3 and -1 /3, respectively. Compared to non-supersymmetric models, there is a variety of new decay modes for the vector-like quarks, involving the extra scalars present in supersymmetry. The importance of these new modes, yielding multi-top, multi-bottom and also multi-Higgs signals, is highlighted by the analysis of several benchmark scenarios. We show how the triangles commonly used to represent the branching ratios of the `standard' decay modes of the vector-like quarks involving W, Z or Higgs bosons can be generalised to include additional channels. We give an example by recasting the limits of a recent heavy quark search for this more general case.
Measuring vector magnetic fields in solar prominences
NASA Astrophysics Data System (ADS)
Orozco Suárez, D.; Asensio Ramos, A.; Trujillo Bueno, J.
2013-05-01
We present spectropolarimetric observations in the He I 1083.0 nm multiplet of a quiescent, hedgerow solar prominence. The data were taken with the Tenerife Infrared Polarimeter attached to the German Vacuum Tower Telescope at the Observatorio del Teide (Tenerife; Canary Islands; Spain). The observed He I circular and linear polarization signals are dominated by the Zeeman effect and by atomic level polarization and the Hanle effect, respectively. These observables are sensitive to the strength and orientation of the magnetic field vector at each spatial point of the field of view. We determine the magnetic field vector of the prominence by applying the HAZEL inversion code to the observed Stokes profiles. We briefly discuss the retrieved magnetic field vector configuration.
Topological phase structure of vector vortex beams.
Souza, C E R; Huguenin, J A O; Khoury, A Z
2014-05-01
The topological phase acquired by vector vortex optical beams is investigated. Under local unitary operations on their polarization and transverse degrees of freedom, the vector vortices can only acquire discrete geometric phase values, 0 or π, associated with closed paths belonging to different homotopy classes on the SO(3) manifold. These discrete values are demonstrated through interferometric measurements, and the spin-orbit mode separability is associated to the visibility of the interference patterns. The local unitary operations performed on the vector vortices involved both polarization and transverse mode transformations with birefringent wave plates and astigmatic mode converters. The experimental results agree with our theoretical simulations and generalize our previous results obtained with polarization transformations only.
Covariant Lyapunov vectors for rigid disk systems
Bosetti, Hadrien; Posch, Harald A.
2010-01-01
We carry out extensive computer simulations to study the Lyapunov instability of a two-dimensional hard-disk system in a rectangular box with periodic boundary conditions. The system is large enough to allow the formation of Lyapunov modes parallel to the x-axis of the box. The Oseledec splitting into covariant subspaces of the tangent space is considered by computing the full set of covariant perturbation vectors co-moving with the flow in tangent space. These vectors are shown to be transversal, but generally not orthogonal to each other. Only the angle between covariant vectors associated with immediate adjacent Lyapunov exponents in the Lyapunov spectrum may become small, but the probability of this angle to vanish approaches zero. The stable and unstable manifolds are transverse to each other and the system is hyperbolic. PMID:21151326
The optical analogy for vector fields
NASA Technical Reports Server (NTRS)
Parker, E. N. (Editor)
1991-01-01
This paper develops the optical analogy for a general vector field. The optical analogy allows the examination of certain aspects of a vector field that are not otherwise readily accessible. In particular, in the cases of a stationary Eulerian flow v of an ideal fluid and a magnetostatic field B, the vectors v and B have surface loci in common with their curls. The intrinsic discontinuities around local maxima in absolute values of v and B take the form of vortex sheets and current sheets, respectively, the former playing a fundamental role in the development of hydrodyamic turbulence and the latter playing a major role in heating the X-ray coronas of stars and galaxies.
Vector control activities. Fiscal year, 1982
Pickard, E.; Cooney, J.C.; McDuff, B.R.
1983-06-01
The goal of the TVA Vector Control Program is to protect the public from potential vectors of disease by controlling medically-important arthropod pests that are propagated on TVA lands or waters. In addition, freedom from annoying mosquitoes and other blood-sucking pests permits the development, use, and full enjoyment of the vast recreational opportunities offered by the many miles of freshwater lakes. To attain this goal the program is divided into operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems that require TVA attention and study. Specifically, activities concerning water level management of TVA lakes, dewatering projects, plant growth control, drainage and insect control programs are detailed. Further, report is made of post-impoundment surveys, soil sampling studies of Mosquite larvae and ecological mosquito management studies.
Application of Bred Vectors To Data Assimilation
NASA Astrophysics Data System (ADS)
Corazza, M.; Kalnay, E.; Patil, Dj
We introduced a statistic, the BV-dimension, to measure the effective local finite-time dimensionality of the atmosphere. We show that this dimension is often quite low, and suggest that this finding has important implications for data assimilation and the accuracy of weather forecasting (Patil et al, 2001). The original database for this study was the forecasts of the NCEP global ensemble forecasting system. The initial differences between the control forecast and the per- turbed forecasts are called bred vectors. The control and perturbed initial conditions valid at time t=n(t are evolved using the forecast model until time t=(n+1) (t. The differences between the perturbed and the control forecasts are scaled down to their initial amplitude, and constitute the bred vectors valid at (n+1) (t. Their growth rate is typically about 1.5/day. The bred vectors are similar by construction to leading Lya- punov vectors except that they have small but finite amplitude, and they are valid at finite times. The original NCEP ensemble data set has 5 independent bred vectors. We define a local bred vector at each grid point by choosing the 5 by 5 grid points centered at the grid point (a region of about 1100km by 1100km), and using the north-south and east- west velocity components at 500mb pressure level to form a 50 dimensional column vector. Since we have k=5 global bred vectors, we also have k local bred vectors at each grid point. We estimate the effective dimensionality of the subspace spanned by the local bred vectors by performing a singular value decomposition (EOF analysis). The k local bred vector columns form a 50xk matrix M. The singular values s(i) of M measure the extent to which the k column unit vectors making up the matrix M point in the direction of v(i). We define the bred vector dimension as BVDIM={Sum[s(i)]}^2/{Sum[s(i)]^2} For example, if 4 out of the 5 vectors lie along v, and one lies along v, the BV- dimension would be BVDIM[sqrt(4), 1, 0
Vectors--shuttle vehicles for gene therapy.
Wilson, J M
1997-01-01
Gene therapy is being considered for the treatment of various inherited and acquired disorders. The basic premise of this new therapeutic modality is manipulation of gene expression towards a therapeutic end. The early development of the field focused on a technique called ex vivo gene therapy in which autologous cells are genetically manipulated in culture prior to transplantation. Recent advances have stimulated the development of in vivo gene therapy approaches based on direct delivery of the therapeutic gene to cells in vivo. The rate-limiting technologies of gene therapy are the gene delivery vehicles, called vectors, used to accomplish gene transfer. The most efficient vectors are based on recombinant versions of viruses with retroviral vectors serving as prototypes. This viral vector system has been exploited in ex vivo approaches of gene therapy in which cultured, dividing cells are transduced with the recombinant virus resulting in integration of the proviral DNA into the chromosomal DNA of the recipient cell. The use of retroviral vectors in gene therapy has been restricted to ex vivo approaches because of difficulties in purifying the virion and the requirement that the target cell is dividing at the time of transduction. More recently, vectors based on adenoviruses have been developed for in vivo gene therapy. These viruses can be grown in large quantities and highly purified. Importantly, they efficiently transduce the recombinant genome into non-dividing cells. Applications include in vivo gene delivery to a variety of targets such as muscle, lung, liver and the central nervous system. Clinical trials of in vivo delivery with adenoviruses have been undertaken for the treatment of cystic fibrosis.
Black hole superradiance signatures of ultralight vectors
NASA Astrophysics Data System (ADS)
Baryakhtar, Masha; Lasenby, Robert; Teo, Mae
2017-08-01
The process of superradiance can extract angular momentum and energy from astrophysical black holes (BHs) to populate gravitationally bound states with an exponentially large number of light bosons. We analytically calculate superradiant growth rates for vectors around rotating BHs in the regime where the vector Compton wavelength is much larger than the BH size. Spin-1 bound states have superradiance times as short as a second around stellar BHs, growing up to a thousand times faster than their spin-0 counterparts. The fast rates allow us to use measurements of rapidly spinning BHs in x-ray binaries to exclude a wide range of masses for weakly coupled spin-1 particles, 5 ×10-14-2 ×10-11 eV ; lighter masses in the range 6 ×10-20-2 ×10-17 eV start to be constrained by supermassive BH spin measurements at a lower level of confidence. We also explore routes to detection of new vector particles possible with the advent of gravitational wave (GW) astronomy. The LIGO-Virgo Collaboration could discover hints of a new light vector particle in statistical analyses of masses and spins of merging BHs. Vector annihilations source continuous monochromatic gravitational radiation which could be observed by current GW observatories. At design sensitivity, Advanced LIGO may measure up to thousands of annihilation signals from within the Milky Way, while hundreds of BHs born in binary mergers across the observable Universe may superradiate vector bound states and become new beacons of monochromatic gravitational waves.
Vector control activities, fiscal year 1983
Pickard, E.; Cooney, J.C.; McDuff, B.R.
1984-07-01
The goal of the Vector Control Program is to safeguard public health and well-being in the Tennessee Valley region by controlling arthropod pests of medical importance that are propagated on TVA lands or waters or that are produced as a result of TVA activities. To achieve this goal the program is divided into two major categories consisting of operations and support studies. The latter is geared to improving the operational effectiveness and efficiency of the control program and to identify additional vector control problems requiring TVA attention and study. Nonchemical methods of control are emphasized and are supplemented with chemical measures as needed.
Raster and vector processing for scanned linework
Greenlee, David D.
1987-01-01
An investigation of raster editing techniques, including thinning, filling, and node detecting, was performed by using specialized software. The techniques were based on encoding the state of the 3-by-3 neighborhood surrounding each pixel into a single byte. A prototypical method for converting the edited raster linkwork into vectors was also developed. Once vector representations of the lines were formed, they were formatted as a Digital Line Graph, and further refined by deletion of nonessential vertices and by smoothing with a curve-fitting technique.
Learning and Memory in Disease Vector Insects.
Vinauger, Clément; Lahondère, Chloé; Cohuet, Anna; Lazzari, Claudio R; Riffell, Jeffrey A
2016-10-01
Learning and memory plays an important role in host preference and parasite transmission by disease vector insects. Historically there has been a dearth of standardized protocols that permit testing their learning abilities, thus limiting discussion on the potential epidemiological consequences of learning and memory to a largely speculative extent. However, with increasing evidence that individual experience and associative learning can affect processes such as oviposition site selection and host preference, it is timely to review the recently acquired knowledge, identify research gaps and discuss the implication of learning in disease vector insects in perspective with control strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.
Spontaneous growth of vector fields in gravity
NASA Astrophysics Data System (ADS)
Ramazanoǧlu, Fethi M.
2017-09-01
We show that the spontaneous scalarization scenario in scalar-tensor theories is a specific case of a more general phenomenon. The key fact is that the instability causing the spontaneous growth in scalars is due to the nonminimal coupling in the theory, and not related to the nature of the scalar. Another field with the same form of coupling undergoes spontaneous growth as well. We explicitly demonstrate this idea for vectors, naming it "spontaneous vectorization", and study spherically symmetric neutron stars in such a theory. We also comment on other tensor fields the idea can be applied, naming the general mechanism "spontaneous tensorization."
Pulse Vector-Excitation Speech Encoder
NASA Technical Reports Server (NTRS)
Davidson, Grant; Gersho, Allen
1989-01-01
Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.
Vector Adaptive/Predictive Encoding Of Speech
NASA Technical Reports Server (NTRS)
Chen, Juin-Hwey; Gersho, Allen
1989-01-01
Vector adaptive/predictive technique for digital encoding of speech signals yields decoded speech of very good quality after transmission at coding rate of 9.6 kb/s and of reasonably good quality at 4.8 kb/s. Requires 3 to 4 million multiplications and additions per second. Combines advantages of adaptive/predictive coding, and code-excited linear prediction, yielding speech of high quality but requires 600 million multiplications and additions per second at encoding rate of 4.8 kb/s. Vector adaptive/predictive coding technique bridges gaps in performance and complexity between adaptive/predictive coding and code-excited linear prediction.
Vector models and generalized SYK models
NASA Astrophysics Data System (ADS)
Peng, Cheng
2017-05-01
We consider the relation between SYK-like models and vector models by studying a toy model where a tensor field is coupled with a vector field. By integrating out the tensor field, the toy model reduces to the Gross-Neveu model in 1 dimension. On the other hand, a certain perturbation can be turned on and the toy model flows to an SYK-like model at low energy. A chaotic-nonchaotic phase transition occurs as the sign of the perturbation is altered. We further study similar models that possess chaos and enhanced reparameterization symmetries.
Vector models and generalized SYK models
Peng, Cheng
2017-05-23
Here, we consider the relation between SYK-like models and vector models by studying a toy model where a tensor field is coupled with a vector field. By integrating out the tensor field, the toy model reduces to the Gross-Neveu model in 1 dimension. On the other hand, a certain perturbation can be turned on and the toy model flows to an SYK-like model at low energy. Furthermore, a chaotic-nonchaotic phase transition occurs as the sign of the perturbation is altered. We further study similar models that possess chaos and enhanced reparameterization symmetries.
Craig, Nathaniel; Knapen, Simon; Longhi, Pietro; ...
2016-07-01
Here, we present a version of the twin Higgs mechanism with vector-like top partners. In this setup all gauge anomalies automatically cancel, even without twin leptons. The matter content of the most minimal twin sector is therefore just two twin tops and one twin bottom. The LHC phenomenology, illustrated with two example models, is dominated by twin glueball decays, possibly in association with Higgs bosons. We further construct an explicit four-dimensional UV completion and discuss a variety of UV completions relevant for both vector-like and fraternal twin Higgs models.
Vector perturbations in a contracting Universe
Battefeld, T.J.; Brandenberger, R.
2004-12-15
In this note we show that vector perturbations exhibit growing mode solutions in a contracting Universe, such as the contracting phase of the pre big bang or the cyclic/ekpyrotic models of the Universe. This is not a gauge artifact and will in general lead to the breakdown of perturbation theory--a severe problem that has to be addressed in any bouncing model. We also comment on the possibility of explaining, by means of primordial vector perturbations, the existence of the observed large-scale magnetic fields. This is possible since they can be seeded by vorticity.
Parasitic diseases in humans transmitted by vectors.
Cholewiński, Marcin; Derda, Monika; Hadaś, Edward
2015-01-01
Despite the considerable progress of medicine, parasitic diseases still pose a great threat to human health and life. Among parasitic diseases, those transmitted by vectors, mainly arthropods, play a particular role. These diseases occur most frequently in the poorest countries and affect a vast part of the human population. They include malaria, babesiosis, trypanosomiasis, leishmaniasis and filariasis. This study presents those vector-transmitted diseases that are responsible for the greatest incidence and mortality of people on a global scale. Attention is focused primarily on diseases transmitted by mosquitoes, flies, Hemiptera and ticks.
Pulse Vector-Excitation Speech Encoder
NASA Technical Reports Server (NTRS)
Davidson, Grant; Gersho, Allen
1989-01-01
Proposed pulse vector-excitation speech encoder (PVXC) encodes analog speech signals into digital representation for transmission or storage at rates below 5 kilobits per second. Produces high quality of reconstructed speech, but with less computation than required by comparable speech-encoding systems. Has some characteristics of multipulse linear predictive coding (MPLPC) and of code-excited linear prediction (CELP). System uses mathematical model of vocal tract in conjunction with set of excitation vectors and perceptually-based error criterion to synthesize natural-sounding speech.
Vector Adaptive/Predictive Encoding Of Speech
NASA Technical Reports Server (NTRS)
Chen, Juin-Hwey; Gersho, Allen
1989-01-01
Vector adaptive/predictive technique for digital encoding of speech signals yields decoded speech of very good quality after transmission at coding rate of 9.6 kb/s and of reasonably good quality at 4.8 kb/s. Requires 3 to 4 million multiplications and additions per second. Combines advantages of adaptive/predictive coding, and code-excited linear prediction, yielding speech of high quality but requires 600 million multiplications and additions per second at encoding rate of 4.8 kb/s. Vector adaptive/predictive coding technique bridges gaps in performance and complexity between adaptive/predictive coding and code-excited linear prediction.
VLSI circuit simulation using a vector computer
NASA Technical Reports Server (NTRS)
Mcgrogan, S. K.
1984-01-01
Simulation of circuits having more than 2000 active devices requires the largest, fastest computers available. A vector computer, such as the CYBER 205, can yield great speed and cost advantages if efforts are made to adapt the simulation program to the strengths of the computer. ASPEC and SPICE (1), two widely used circuit simulation programs, are discussed. ASPECV and VAMOS (5) are respectively vector adaptations of these two simulators. They demonstrate the substantial performance enhancements possible for this class of algorithm on the CYBER 205.
Molecular Genetic Manipulation of Vector Mosquitoes
Terenius, Olle; Marinotti, Osvaldo; Sieglaff, Douglas; James, Anthony A.
2008-01-01
Genetic strategies for reducing populations of vector mosquitoes or replacing them with those that are not able to transmit pathogens benefit greatly from molecular tools that allow gene manipulation and transgenesis. Mosquito genome sequences and associated EST (Expressed Sequence Tags) databases enable large-scale investigations to provide new insights into evolutionary, biochemical, genetic, metabolic and physiological pathways. Additionally, comparative genomics reveals the bases for evolutionary mechanisms with particular focus on specific interactions between vectors and pathogens. We discuss how this information may be exploited for the optimization of transgenes that interfere with the propagation and development of pathogens in their mosquito hosts. PMID:18996342
The Inside Out of Lentiviral Vectors
Durand, Stéphanie; Cimarelli, Andrea
2011-01-01
Lentiviruses induce a wide variety of pathologies in different animal species. A common feature of the replicative cycle of these viruses is their ability to target non-dividing cells, a property that constitutes an extremely attractive asset in gene therapy. In this review, we shall describe the main basic aspects of the virology of lentiviruses that were exploited to obtain efficient gene transfer vectors. In addition, we shall discuss some of the hurdles that oppose the efficient genetic modification mediated by lentiviral vectors and the strategies that are being developed to circumvent them. PMID:22049307
Craig, Nathaniel; Knapen, Simon; Longhi, Pietro; Strassler, Matthew
2016-07-01
Here, we present a version of the twin Higgs mechanism with vector-like top partners. In this setup all gauge anomalies automatically cancel, even without twin leptons. The matter content of the most minimal twin sector is therefore just two twin tops and one twin bottom. The LHC phenomenology, illustrated with two example models, is dominated by twin glueball decays, possibly in association with Higgs bosons. We further construct an explicit four-dimensional UV completion and discuss a variety of UV completions relevant for both vector-like and fraternal twin Higgs models.
Aircraft attitude measurement using a vector magnetometer
NASA Technical Reports Server (NTRS)
Peitila, R.; Dunn, W. R., Jr.
1977-01-01
The feasibility of a vector magnetometer system was investigated by developing a technique to determine attitude given magnetic field components. Sample calculations are then made using the earth's magnetic field data acquired during actual flight conditions. Results of these calculations are compared graphically with measured attitude data acquired simultaneously with the magnetic data. The role and possible implementation of various reference angles are discussed along with other pertinent considerations. Finally, it is concluded that the earth's magnetic field as measured by modern vector magnetometers can play a significant role in attitude control systems.
Brand, Samuel P. C.; Keeling, Matt J.
2016-01-01
Epidemiological modelling has a vital role to play in policy planning and prediction for the control of vectors, and hence the subsequent control of vector-borne diseases. To decide between competing policies requires models that can generate accurate predictions, which in turn requires accurate knowledge of vector natural histories. Here we highlight the importance of the distribution of times between life-history events, using short-lived midge species as an example. In particular we focus on the distribution of the extrinsic incubation period (EIP) which determines the time between infection and becoming infectious, and the distribution of the length of the gonotrophic cycle which determines the time between successful bites. We show how different assumptions for these periods can radically change the basic reproductive ratio (R0) of an infection and additionally the impact of vector control on the infection. These findings highlight the need for detailed entomological data, based on laboratory experiments and field data, to correctly construct the next-generation of policy-informing models. PMID:27128163
Brand, Samuel P C; Rock, Kat S; Keeling, Matt J
2016-04-01
Epidemiological modelling has a vital role to play in policy planning and prediction for the control of vectors, and hence the subsequent control of vector-borne diseases. To decide between competing policies requires models that can generate accurate predictions, which in turn requires accurate knowledge of vector natural histories. Here we highlight the importance of the distribution of times between life-history events, using short-lived midge species as an example. In particular we focus on the distribution of the extrinsic incubation period (EIP) which determines the time between infection and becoming infectious, and the distribution of the length of the gonotrophic cycle which determines the time between successful bites. We show how different assumptions for these periods can radically change the basic reproductive ratio (R0) of an infection and additionally the impact of vector control on the infection. These findings highlight the need for detailed entomological data, based on laboratory experiments and field data, to correctly construct the next-generation of policy-informing models.
Boeckle, Sabine; Wagner, Ernst
2006-01-01
In comparison to classical medicines, gene therapy has the potential to mediate the highest possible level of therapeutic specificity. Every normal or diseased cell can switch on or off a gene expression cassette in a tissue-, disease-, and time-dependent fashion, by use of specific transcription factors that are active only in a given unique situation. In practice, we face the problem in realizing the concept: the delivery of nucleic acids into target cells is very ineffective and presents a formidable challenge. Key issues for future developments include improved targeting, enhanced intracellular uptake, and reduced toxicity of gene vectors. The currently used classes of vectors have complementary characteristics, such as high intracellular efficiency of viral vectors on the one hand and low immunogenicity and greater flexibility of nonviral vectors on the other hand. The merge of viral and nonviral vector technologies is highlighted as an encouraging strategy for the future; concepts include chemically modified viral vectors ("chemo-viruses") and synthesis of virus-like systems ("synthetic viruses"). Examples for the development of vectors toward artificial synthetic viruses are presented.
Okamoto, Kenichi W.; Gould, Fred; Lloyd, Alun L.
2016-01-01
Many vector-borne diseases lack effective vaccines and medications, and the limitations of traditional vector control have inspired novel approaches based on using genetic engineering to manipulate vector populations and thereby reduce transmission. Yet both the short- and long-term epidemiological effects of these transgenic strategies are highly uncertain. If neither vaccines, medications, nor transgenic strategies can by themselves suffice for managing vector-borne diseases, integrating these approaches becomes key. Here we develop a framework to evaluate how clinical interventions (i.e., vaccination and medication) can be integrated with transgenic vector manipulation strategies to prevent disease invasion and reduce disease incidence. We show that the ability of clinical interventions to accelerate disease suppression can depend on the nature of the transgenic manipulation deployed (e.g., whether vector population reduction or replacement is attempted). We find that making a specific, individual strategy highly effective may not be necessary for attaining public-health objectives, provided suitable combinations can be adopted. However, we show how combining only partially effective antimicrobial drugs or vaccination with transgenic vector manipulations that merely temporarily lower vector competence can amplify disease resurgence following transient suppression. Thus, transgenic vector manipulation that cannot be sustained can have adverse consequences—consequences which ineffective clinical interventions can at best only mitigate, and at worst temporarily exacerbate. This result, which arises from differences between the time scale on which the interventions affect disease dynamics and the time scale of host population dynamics, highlights the importance of accounting for the potential delay in the effects of deploying public health strategies on long-term disease incidence. We find that for systems at the disease-endemic equilibrium, even modest
Peterson, Jennifer K; Bartsch, Sarah M; Lee, Bruce Y; Dobson, Andrew P
2015-10-22
Chagas disease (caused by Trypanosoma cruzi) is the most important neglected tropical disease (NTD) in Latin America, infecting an estimated 5.7 million people in the 21 countries where it is endemic. It is one of the NTDs targeted for control and elimination by the 2020 London Declaration goals, with the first goal being to interrupt intra-domiciliary vector-borne T. cruzi transmission. A key question in domestic T. cruzi transmission is the role that synanthropic animals play in T. cruzi transmission to humans. Here, we ask, (1) do synanthropic animals need to be targeted in Chagas disease prevention policies?, and (2) how does the presence of animals affect the efficacy of vector control? We developed a simple mathematical model to simulate domestic vector-borne T. cruzi transmission and to specifically examine the interaction between the presence of synanthropic animals and effects of vector control. We used the model to explore how the interactions between triatomine bugs, humans and animals impact the number and proportion of T. cruzi-infected bugs and humans. We then examined how T. cruzi dynamics change when control measures targeting vector abundance are introduced into the system. We found that the presence of synanthropic animals slows the speed of T. cruzi transmission to humans, and increases the sensitivity of T. cruzi transmission dynamics to vector control measures at comparable triatomine carrying capacities. However, T. cruzi transmission is amplified when triatomine carrying capacity increases with the abundance of syntathoropic hosts. Our results suggest that in domestic T. cruzi transmission scenarios where no vector control measures are in place, a reduction in synanthropic animals may slow T. cruzi transmission to humans, but it would not completely eliminate transmission. To reach the 2020 goal of interrupting intra-domiciliary T. cruzi transmission, it is critical to target vector populations. Additionally, where vector control measures
Predictive vector quantization using a neural network approach
NASA Astrophysics Data System (ADS)
Mohsenian, Nader; Rizvi, Syed A.; Nasrabadi, Nasser M.
1993-07-01
A new predictive vector quantization (PVQ) technique capable of exploring the nonlinear dependencies in addition to the linear dependencies that exist between adjacent blocks (vectors) of pixels is introduced. The two components of the PVQ scheme, the vector predictor and the vector quantizer, are implemented by two different classes of neural networks. A multilayer perceptron is used for the predictive component and Kohonen self- organizing feature maps are used to design the codebook for the vector quantizer. The multilayer perceptron uses the nonlinearity condition associated with its processing units to perform a nonlinear vector prediction. The second component of the PVQ scheme vector quantizers the residual vector that is formed by subtracting the output of the perceptron from the original input vector. The joint-optimization task of designing the two components of the PVQ scheme is also achieved. Simulation results are presented for still images with high visual quality.
Integrated strategy for the production of therapeutic retroviral vectors.
Carrondo, Manuel; Panet, Amos; Wirth, Dagmar; Coroadinha, Ana Sofia; Cruz, Pedro; Falk, Haya; Schucht, Roland; Dupont, Francis; Geny-Fiamma, Cécile; Merten, Otto-Wilhelm; Hauser, Hansjörg
2011-03-01
The broad application of retroviral vectors for gene delivery is still hampered by the difficulty to reproducibly establish high vector producer cell lines generating sufficient amounts of highly concentrated virus vector preparations of high quality. To enhance the process for producing clinically relevant retroviral vector preparations for therapeutic applications, we have integrated novel and state-of-the-art technologies in a process that allows rapid access to high-efficiency vector-producing cells and consistent production, purification, and storage of retroviral vectors. The process has been designed for various types of retroviral vectors for clinical application and to support a high-throughput process. New modular helper cell lines that permit rapid insertion of DNA encoding the therapeutic vector of interest at predetermined, optimal chromosomal loci were developed to facilitate stable and high vector production levels. Packaging cell lines, cultivation methods, and improved medium composition were coupled with vector purification and storage process strategies that yield maximal vector infectivity and stability. To facilitate GMP-grade vector production, standard of operation protocols were established. These processes were validated by production of retroviral vector lots that drive the expression of type VII collagen (Col7) for the treatment of a skin genetic disease, dystrophic epidermolysis bullosa. The potential efficacy of the Col7-expressing vectors was finally proven with newly developed systems, in particular in target primary keratinocyte cultures and three-dimensional skin tissues in organ culture.
Constraining vectors and axial-vectors in walking technicolor by a holographic principle
Dietrich, Dennis D.; Kouvaris, Chris
2008-09-01
We use a holographic principle to study the low-energy spectrum of walking technicolor models. In particular, we predict the masses of the axial-vectors as well as the decay constants of vectors and axial-vectors as functions of the mass of the techni-{rho}. Given that there are very few nonperturbative techniques to study strongly coupled theories, using holography might provide us with insight into how to constrain the parameters of the low-energy effective action of walking technicolor models. We also compare our results with findings from other setups.
Flood Classification Using Support Vector Machines
NASA Astrophysics Data System (ADS)
Melsen, Lieke A.; Torfs, Paul J. J.; Brauer, Claudia C.
2013-04-01
Lowland floods are in general considered to be less extreme than mountainous floods. In order to investigate this, seven lowland floods in the Netherlands were selected and compared to mountainous floods from the study of Marchi et al. (2010). Both a 2D and 3D approach of the statistical two-group classification method support vector machines (Cortes and Vapnik, 1995) were used to find a statistical difference between the two flood types. Support vector machines were able to draw a decision plane between the two flood types, misclassifying one out of seven lowland floods, and one out of 67 mountainous floods. The main difference between the two flood types can be found in the runoff coefficient (with lowland floods having a lower runoff coefficient than mountainous floods), the cumulative precipitation causing the flood (which was lower for lowland floods), and, obviously, the relief ratio. Support vector machines have proved to be useful for flood classification and might be applicable in future classification studies. References Cortes, C., and V. Vapnik. "Support-Vector Networks." Machine Learning 20: (1995) 273-297. Marchi, L., M. Borga, E. Preciso, and E. Gaume. "Characterisation of selected extreme flash floods in Europe and implications for flood risk management." Journal of Hydrology 394: (2010) 118-133.
Circular Conditional Autoregressive Modeling of Vector Fields.
Modlin, Danny; Fuentes, Montse; Reich, Brian
2012-02-01
As hurricanes approach landfall, there are several hazards for which coastal populations must be prepared. Damaging winds, torrential rains, and tornadoes play havoc with both the coast and inland areas; but, the biggest seaside menace to life and property is the storm surge. Wind fields are used as the primary forcing for the numerical forecasts of the coastal ocean response to hurricane force winds, such as the height of the storm surge and the degree of coastal flooding. Unfortunately, developments in deterministic modeling of these forcings have been hindered by computational expenses. In this paper, we present a multivariate spatial model for vector fields, that we apply to hurricane winds. We parameterize the wind vector at each site in polar coordinates and specify a circular conditional autoregressive (CCAR) model for the vector direction, and a spatial CAR model for speed. We apply our framework for vector fields to hurricane surface wind fields for Hurricane Floyd of 1999 and compare our CCAR model to prior methods that decompose wind speed and direction into its N-S and W-E cardinal components.
Vector coding of wavelet-transformed images
NASA Astrophysics Data System (ADS)
Zhou, Jun; Zhi, Cheng; Zhou, Yuanhua
1998-09-01
Wavelet, as a brand new tool in signal processing, has got broad recognition. Using wavelet transform, we can get octave divided frequency band with specific orientation which combines well with the properties of Human Visual System. In this paper, we discuss the classified vector quantization method for multiresolution represented image.
Multipole vector solitons in nonlocal nonlinear media.
Kartashov, Yaroslav V; Torner, Lluis; Vysloukh, Victor A; Mihalache, Dumitru
2006-05-15
We show that multipole solitons can be made stable via vectorial coupling in bulk nonlocal nonlinear media. Such vector solitons are composed of mutually incoherent nodeless and multipole components jointly inducing a nonlinear refractive index profile. We found that stabilization of the otherwise highly unstable multipoles occurs below certain maximum energy flow. Such a threshold is determined by the nonlocality degree.
Students' Difficulties with Vector Calculus in Electrodynamics
ERIC Educational Resources Information Center
Bollen, Laurens; van Kampen, Paul; De Cock, Mieke
2015-01-01
Understanding Maxwell's equations in differential form is of great importance when studying the electrodynamic phenomena discussed in advanced electromagnetism courses. It is therefore necessary that students master the use of vector calculus in physical situations. In this light we investigated the difficulties second year students at KU Leuven…
Topology based methods for vector field comparisons
NASA Astrophysics Data System (ADS)
Batra, Rajesh Kumar
Vector fields are commonly found in almost all branches of the physical sciences. Aerodynamics, dynamical systems, electromagnetism, and global climate modeling are a few examples. These multivariate data fields are often large, and no general, automated method exists for comparing these fields. Existing methods require either subjective visual judgments, or data interface compatibility, or domain specific knowledge. A topology based method intrinsically eliminates all of the above limitations and has the additional advantage of significantly compressing the vector field by representing only key features of the flow. Therefore, large databases are compactly represented and quickly searched. Topology is a natural framework for the study of many vector fields. It provides rules of an organizing principle, a flow grammar, that can describe and connect together the properties common to flows. Helman and Hesselink first introduced automated methods to extract and visualize this grammar. This work extends their method by introducing automated methods for vector topology comparison. Basic two-dimensional flows are first compared. The theory is extended to compare three-dimensional flow fields and the topology on no-slip surfaces. Concepts from graph theory and linear programming are utilized to solve these problems. Finally, the first automated method for higher order singularity comparisons is introduced using mathematical theories from geometric (Clifford) algebra.
Comparison between covariant and orthogonal Lyapunov vectors.
Yang, Hong-liu; Radons, Günter
2010-10-01
Two sets of vectors, covariant Lyapunov vectors (CLVs) and orthogonal Lyapunov vectors (OLVs), are currently used to characterize the linear stability of chaotic systems. A comparison is made to show their similarity and difference, especially with respect to the influence on hydrodynamic Lyapunov modes (HLMs). Our numerical simulations show that in both Hamiltonian and dissipative systems HLMs formerly detected via OLVs survive if CLVs are used instead. Moreover, the previous classification of two universality classes works for CLVs as well, i.e., the dispersion relation is linear for Hamiltonian systems and quadratic for dissipative systems, respectively. The significance of HLMs changes in different ways for Hamiltonian and dissipative systems with the replacement of OLVs with CLVs. For general dissipative systems with nonhyperbolic dynamics the long-wavelength structure in Lyapunov vectors corresponding to near-zero Lyapunov exponents is strongly reduced if CLVs are used instead, whereas for highly hyperbolic dissipative systems the significance of HLMs is nearly identical for CLVs and OLVs. In contrast the HLM significance of Hamiltonian systems is always comparable for CLVs and OLVs irrespective of hyperbolicity. We also find that in Hamiltonian systems different symmetry relations between conjugate pairs are observed for CLVs and OLVs. Especially, CLVs in a conjugate pair are statistically indistinguishable in consequence of the microreversibility of Hamiltonian systems. Transformation properties of Lyapunov exponents, CLVs, and hyperbolicity under changes of coordinate are discussed in appendices.
Global traffic and disease vector dispersal
Tatem, Andrew J.; Hay, Simon I.; Rogers, David J.
2006-01-01
The expansion of global air travel and seaborne trade overcomes geographic barriers to insect disease vectors, enabling them to move great distances in short periods of time. Here we apply a coupled human–environment framework to describe the historical spread of Aedes albopictus, a competent mosquito vector of 22 arboviruses in the laboratory. We contrast this dispersal with the relatively unchanged distribution of Anopheles gambiae and examine possible future movements of this malaria vector. We use a comprehensive database of international ship and aircraft traffic movements, combined with climatic information, to remap the global transportation network in terms of disease vector suitability and accessibility. The expansion of the range of Ae. albopictus proved to be surprisingly predictable using this combination of climate and traffic data. Traffic volumes were more than twice as high on shipping routes running from the historical distribution of Ae. albopictus to ports where it has established in comparison with routes to climatically similar ports where it has yet to invade. In contrast, An. gambiae has rarely spread from Africa, which we suggest is partly due to the low volume of sea traffic from the continent and, until very recently, a European destination for most flights. PMID:16606847
A Lesson in Vectors "Plain" and Simple
ERIC Educational Resources Information Center
Bradshaw, David M.
2004-01-01
The United States Military Academy (USMA) has a four course core mathematics curriculum that is studied by all students. The third course is MA205, Calculus II; a multivariate calculus course filled with practical applications. During a Problem Solving Lab (PSL), students participated in a hands-on exercise with multiple vector operations,…
Dispersing hemipteran vectors have reduced arbovirus prevalence
Moore, Amy T.; Brown, Charles R.
2014-01-01
A challenge in managing vector-borne zoonotic diseases in human and wildlife populations is predicting where epidemics or epizootics are likely to occur, and this requires knowing in part the likelihood of infected insect vectors dispersing pathogens from existing infection foci to novel areas. We measured prevalence of an arbovirus, Buggy Creek virus, in dispersing and resident individuals of its exclusive vector, the ectoparasitic swallow bug (Oeciacus vicarius), that occupies cliff swallow (Petrochelidon pyrrhonota) colonies in western Nebraska. Bugs colonizing new colony sites and immigrating into established colonies by clinging to the swallows’ legs and feet had significantly lower virus prevalence than bugs in established colonies and those that were clustering in established colonies before dispersing. The reduced likelihood of infected bugs dispersing to new colony sites indicates that even heavily infected sites may not always export virus to nearby foci at a high rate. Infected arthropods should not be assumed to exhibit the same dispersal or movement behaviour as uninfected individuals, and these differences in dispersal should perhaps be considered in the epidemiology of vector-borne pathogens such as arboviruses. PMID:24694692
Hamiltonian vector fields on almost symplectic manifolds
NASA Astrophysics Data System (ADS)
Vaisman, Izu
2013-09-01
Let (M, ω) be an almost symplectic manifold (ω is a nondegenerate, not closed, 2-form). We say that a vector field X of M is locally Hamiltonian if LXω = 0, d(i(X)ω) = 0, and it is Hamiltonian if, furthermore, the 1-form i(X)ω is exact. Such vector fields were considered in Fassò and Sansonetto ["Integrable almost-symplectic Hamiltonian systems," J. Math. Phys. 48, 092902 (2007)], 10.1063/1.2783937, under the name of strongly Hamiltonian, and a corresponding action-angle theorem was proven. Almost symplectic manifolds may have few, nonzero, Hamiltonian vector fields, or even none. Therefore, it is important to have examples and it is our aim to provide such examples here. We also obtain some new general results. In particular, we show that the locally Hamiltonian vector fields generate a Dirac structure on M and we state a reduction theorem of the Marsden-Weinstein type. A final section is dedicated to almost symplectic structures on tangent bundles.
Teaching Universal Gravitation with Vector Games
ERIC Educational Resources Information Center
Lowry, Matthew
2008-01-01
Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to…
Viral vectors for therapy of neurologic diseases.
Choudhury, Sourav R; Hudry, Eloise; Maguire, Casey A; Sena-Esteves, Miguel; Breakefield, Xandra O; Grandi, Paola
2017-07-01
Neurological disorders - disorders of the brain, spine and associated nerves - are a leading contributor to global disease burden with a shockingly large associated economic cost. Various treatment approaches - pharmaceutical medication, device-based therapy, physiotherapy, surgical intervention, among others - have been explored to alleviate the resulting extent of human suffering. In recent years, gene therapy using viral vectors - encoding a therapeutic gene or inhibitory RNA into a "gutted" viral capsid and supplying it to the nervous system - has emerged as a clinically viable option for therapy of brain disorders. In this Review, we provide an overview of the current state and advances in the field of viral vector-mediated gene therapy for neurological disorders. Vector tools and delivery methods have evolved considerably over recent years, with the goal of providing greater and safer genetic access to the central nervous system. Better etiological understanding of brain disorders has concurrently led to identification of improved therapeutic targets. We focus on the vector technology, as well as preclinical and clinical progress made thus far for brain cancer and various neurodegenerative and neurometabolic disorders, and point out the challenges and limitations that accompany this new medical modality. Finally, we explore the directions that neurological gene therapy is likely to evolve towards in the future. This article is part of the Special Issue entitled "Beyond small molecules for neurological disorders". Copyright © 2016 Elsevier Ltd. All rights reserved.
Virus-vectored immunocontraception of feral mammals.
Tyndale-Biscoe, C H
1994-01-01
The potential value of immunosterilization as a means to control species of wildlife that are widespread, numerous and undesirable is assessed. Key questions about the efficacy of fertility control and the means for delivering antigens expressed in recombinant viral vectors are discussed and the legal and social concerns that relate to its possible future use are raised.
Circular Conditional Autoregressive Modeling of Vector Fields*
Modlin, Danny; Fuentes, Montse; Reich, Brian
2013-01-01
As hurricanes approach landfall, there are several hazards for which coastal populations must be prepared. Damaging winds, torrential rains, and tornadoes play havoc with both the coast and inland areas; but, the biggest seaside menace to life and property is the storm surge. Wind fields are used as the primary forcing for the numerical forecasts of the coastal ocean response to hurricane force winds, such as the height of the storm surge and the degree of coastal flooding. Unfortunately, developments in deterministic modeling of these forcings have been hindered by computational expenses. In this paper, we present a multivariate spatial model for vector fields, that we apply to hurricane winds. We parameterize the wind vector at each site in polar coordinates and specify a circular conditional autoregressive (CCAR) model for the vector direction, and a spatial CAR model for speed. We apply our framework for vector fields to hurricane surface wind fields for Hurricane Floyd of 1999 and compare our CCAR model to prior methods that decompose wind speed and direction into its N-S and W-E cardinal components. PMID:24353452
Angry Birds Mathematics: Parabolas and Vectors
ERIC Educational Resources Information Center
Lamb, John H.
2013-01-01
John Lamb, a professor of mathematics education and a teacher of high school precalculus, describes how he developed a way to use the elements of the game Angry Birds® as a platform to engage his students with the concepts of parabolas and vectors. The game could be categorized as a type of microworld game in which students interact with the…
Global traffic and disease vector dispersal.
Tatem, Andrew J; Hay, Simon I; Rogers, David J
2006-04-18
The expansion of global air travel and seaborne trade overcomes geographic barriers to insect disease vectors, enabling them to move great distances in short periods of time. Here we apply a coupled human-environment framework to describe the historical spread of Aedes albopictus, a competent mosquito vector of 22 arboviruses in the laboratory. We contrast this dispersal with the relatively unchanged distribution of Anopheles gambiae and examine possible future movements of this malaria vector. We use a comprehensive database of international ship and aircraft traffic movements, combined with climatic information, to remap the global transportation network in terms of disease vector suitability and accessibility. The expansion of the range of Ae. albopictus proved to be surprisingly predictable using this combination of climate and traffic data. Traffic volumes were more than twice as high on shipping routes running from the historical distribution of Ae. albopictus to ports where it has established in comparison with routes to climatically similar ports where it has yet to invade. In contrast, An. gambiae has rarely spread from Africa, which we suggest is partly due to the low volume of sea traffic from the continent and, until very recently, a European destination for most flights.
Population structure of an island malaria vector.
Foley, D H; Torres, E P
2006-12-01
The impact of islands on the population structure of Anopheles flavirostris (Ludlow) (Diptera: Culicidae), the primary malaria vector in the Philippines, was assessed. A phylogenetic analysis of 16 cytochrome oxidase subunit 1 (CO1) haplotypes revealed three clades: one basal clade containing genetically disparate haplotypes from Mindanao, and two derived clades, one of which was largely confined to the largest island, Luzon, and one that was widespread except for Luzon. For the Luzon clade, nested clade analysis revealed an isolation-by-distance effect, and a mismatch distribution analysis diagnosed a recent demographic expansion (sum of squared deviation, SDD = 0.0093, P= 0.075), which mirrors demographic attributes found in mainland primary malaria vectors and could inflate estimates of gene flow from F(ST). For the widespread clade, evidence of range expansion and past fragmentation and/or long distance colonization from the Visayas or Mindanao to Palawan is suggested. A south-to-north range expansion of An. flavirostris is suggested; estimates of coalescence for the Luzon clade was 214 000 years ago (ya) (95% confidence interval 35 600-298 000 ya), i.e. late Pleistocene. Present day rather than Pleistocene island association and some, but not all, sea barriers appeared to be important for An. flavirostris population structure. Our results suggest that endemic island malaria vector species need to be considered before any generalizations are made about the population structure of primary and secondary vectors.
Angry Birds Mathematics: Parabolas and Vectors
ERIC Educational Resources Information Center
Lamb, John H.
2013-01-01
John Lamb, a professor of mathematics education and a teacher of high school precalculus, describes how he developed a way to use the elements of the game Angry Birds® as a platform to engage his students with the concepts of parabolas and vectors. The game could be categorized as a type of microworld game in which students interact with the…
MHD thrust vectoring of a rocket engine
NASA Astrophysics Data System (ADS)
Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic
2016-09-01
In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.
Vector leptoquark production at hadron colliders
Hewett, J.L.; Rizzo, T.G.; Pakvasa, S.; Haber, H.E.; Pomarol, A.
1993-09-01
We explore the production of vector leptoquarks(V) at the Tevatron, LHC, and SSC through both quark-antiquark and gluon fusion: q{bar q}, gg {yields} VV. The cross sections are found to be somewhat larger than for scalar leptoquarks of the same mass implying enhanced search capabilities.
Combining Vector Quantization and Histogram Equalization.
ERIC Educational Resources Information Center
Cosman, Pamela C.; And Others
1992-01-01
Discussion of contrast enhancement techniques focuses on the use of histogram equalization with a data compression technique, i.e., tree-structured vector quantization. The enhancement technique of intensity windowing is described, and the use of enhancement techniques for medical images is explained, including adaptive histogram equalization.…
Vector mesons as a Higgs phenomenon
Hajuj, O. )
1990-07-01
We propose an approach to couple vector mesons to the Skyrme model. We show that classically the model exhibits stable hedgehog baryons. The classically stable solutions are quantized. The nucleon-{Delta} splitting is found to be in good agreement with experimental results.
Mosquito Oviposition Behavior and Vector Control
Day, Jonathan F.
2016-01-01
The burden of gene transfer from one mosquito generation to the next falls on the female and her eggs. The selection of an oviposition site that guarantees egg and larval survival is a critical step in the reproductive process. The dangers associated with ephemeral aquatic habitats, lengthy droughts, freezing winters, and the absence of larval nutrition makes careful oviposition site selection by a female mosquito extremely important. Mosquito species exhibit a remarkable diversity of oviposition behaviors that ensure eggs are deposited into microenvironments conducive for successful larval development and the emergence of the next mosquito generation. An understanding of mosquito oviposition behavior is necessary for the development of surveillance and control opportunities directed against specific disease vectors. For example, Aedes aegypti Linnaeus is the vector of viruses causing important human diseases including yellow fever, dengue, chikungunya, and Zika. The preference of this species to oviposit in natural and artificial containers has facilitated the development of Ae. aegypti-specific surveillance and toxic oviposition traps designed to detect and control this important vector species in and around disease foci. A better understanding of the wide diversity of mosquito oviposition behavior will allow the development of new and innovative surveillance and control devices directed against other important mosquito vectors of human and animal disease. PMID:27869724
A Vector Representation for Thermodynamic Relationships
ERIC Educational Resources Information Center
Pogliani, Lionello
2006-01-01
The existing vector formalism method for thermodynamic relationship maintains tractability and uses accessible mathematics, which can be seen as a diverting and entertaining step into the mathematical formalism of thermodynamics and as an elementary application of matrix algebra. The method is based on ideas and operations apt to improve the…
Vector Potential, Electromagnetic Induction and "Physical Meaning"
ERIC Educational Resources Information Center
Giuliani, G.
2010-01-01
A forgotten experiment by Andre Blondel (1914) proves, as held on the basis of theoretical arguments in a previous paper, that the time variation of the magnetic flux is not the cause of the induced emf; the physical agent is instead the vector potential through the term [equation omitted] (when the induced circuit is at rest). The "good…
Vector Potential, Electromagnetic Induction and "Physical Meaning"
ERIC Educational Resources Information Center
Giuliani, G.
2010-01-01
A forgotten experiment by Andre Blondel (1914) proves, as held on the basis of theoretical arguments in a previous paper, that the time variation of the magnetic flux is not the cause of the induced emf; the physical agent is instead the vector potential through the term [equation omitted] (when the induced circuit is at rest). The "good…
Mosquito Oviposition Behavior and Vector Control.
Day, Jonathan F
2016-11-18
The burden of gene transfer from one mosquito generation to the next falls on the female and her eggs. The selection of an oviposition site that guarantees egg and larval survival is a critical step in the reproductive process. The dangers associated with ephemeral aquatic habitats, lengthy droughts, freezing winters, and the absence of larval nutrition makes careful oviposition site selection by a female mosquito extremely important. Mosquito species exhibit a remarkable diversity of oviposition behaviors that ensure eggs are deposited into microenvironments conducive for successful larval development and the emergence of the next mosquito generation. An understanding of mosquito oviposition behavior is necessary for the development of surveillance and control opportunities directed against specific disease vectors. For example, Aedes aegypti Linnaeus is the vector of viruses causing important human diseases including yellow fever, dengue, chikungunya, and Zika. The preference of this species to oviposit in natural and artificial containers has facilitated the development of Ae. aegypti-specific surveillance and toxic oviposition traps designed to detect and control this important vector species in and around disease foci. A better understanding of the wide diversity of mosquito oviposition behavior will allow the development of new and innovative surveillance and control devices directed against other important mosquito vectors of human and animal disease.
Students' Difficulties with Vector Calculus in Electrodynamics
ERIC Educational Resources Information Center
Bollen, Laurens; van Kampen, Paul; De Cock, Mieke
2015-01-01
Understanding Maxwell's equations in differential form is of great importance when studying the electrodynamic phenomena discussed in advanced electromagnetism courses. It is therefore necessary that students master the use of vector calculus in physical situations. In this light we investigated the difficulties second year students at KU Leuven…
Teaching Universal Gravitation with Vector Games
ERIC Educational Resources Information Center
Lowry, Matthew
2008-01-01
Like many high school and college physics teachers, I have found playing vector games to be a useful way of illustrating the concepts of inertia, velocity, and acceleration. Like many, I have also had difficulty in trying to get students to understand Newton's law of universal gravitation, specifically the inverse-square law and its application to…
Generalized vector calculus on convex domain
NASA Astrophysics Data System (ADS)
Agrawal, Om P.; Xu, Yufeng
2015-06-01
In this paper, we apply recently proposed generalized integral and differential operators to develop generalized vector calculus and generalized variational calculus for problems defined over a convex domain. In particular, we present some generalization of Green's and Gauss divergence theorems involving some new operators, and apply these theorems to generalized variational calculus. For fractional power kernels, the formulation leads to fractional vector calculus and fractional variational calculus for problems defined over a convex domain. In special cases, when certain parameters take integer values, we obtain formulations for integer order problems. Two examples are presented to demonstrate applications of the generalized variational calculus which utilize the generalized vector calculus developed in the paper. The first example leads to a generalized partial differential equation and the second example leads to a generalized eigenvalue problem, both in two dimensional convex domains. We solve the generalized partial differential equation by using polynomial approximation. A special case of the second example is a generalized isoperimetric problem. We find an approximate solution to this problem. Many physical problems containing integer order integrals and derivatives are defined over arbitrary domains. We speculate that future problems containing fractional and generalized integrals and derivatives in fractional mechanics will be defined over arbitrary domains, and therefore, a general variational calculus incorporating a general vector calculus will be needed for these problems. This research is our first attempt in that direction.
Adenoassociated virus vectors for genetic immunization.
Ponnazhagan, Selvarangan
2002-01-01
Genetic immunization has initiated a new era of vaccine research, which provides a stable and long-lived source of the protein antigen. Such a vaccine is a simple, robust, and effective means of eliciting both antibody- and cell-mediated immune responses compared with protein or peptide vaccines. Although naked DNA vaccines are relatively simple to produce and handle without significant toxicity or host immunity, those using viral vectors have shown greater efficacy in gene transfer and in inducing both protective and therapeutic immunity in preclinical models. However, clinical translation of results obtained in animal studies with viral vectors has not met with anticipated success so far because of inherent limitations of the vector-associated immunity and antigen specificity. Thus, understanding the requirements for the elicitation of target-specific immunity in host requires that a major cellular arm be unraveled, and modifications of the existing viral vectors and testing of newer ones encompass the technological arm of vaccine research. In this article, I give a comprehensive account of the potential of adenoassociated virus, a nonpathogenic human parvovirus in vaccine development.
Lentiviral Vectors and Cystic Fibrosis Gene Therapy
Castellani, Stefano; Conese, Massimo
2010-01-01
Cystic fibrosis (CF) is a chronic autosomic recessive syndrome, caused by mutations in the CF Transmembrane Conductance Regulator (CFTR) gene, a chloride channel expressed on the apical side of the airway epithelial cells. The lack of CFTR activity brings a dysregulated exchange of ions and water through the airway epithelium, one of the main aspects of CF lung disease pathophysiology. Lentiviral (LV) vectors, of the Retroviridae family, show interesting properties for CF gene therapy, since they integrate into the host genome and allow long-lasting gene expression. Proof-of-principle that LV vectors can transduce the airway epithelium and correct the basic electrophysiological defect in CF mice has been given. Initial data also demonstrate that LV vectors can be repeatedly administered to the lung and do not give rise to a gross inflammatory process, although they can elicit a T cell-mediated response to the transgene. Future studies will clarify the efficacy and safety profile of LV vectors in new complex animal models with CF, such as ferrets and pigs. PMID:21994643
Vector Reflectometry in a Beam Waveguide
NASA Technical Reports Server (NTRS)
Eimer, J. R.; Bennett, C. L.; Chuss, D. T.; Wollack, E. J.
2011-01-01
We present a one-port calibration technique for characterization of beam waveguide components with a vector network analyzer. This technique involves using a set of known delays to separate the responses of the instrument and the device under test. We demonstrate this technique by measuring the reflected performance of a millimeter-wave variable-delay polarization modulator.
Ascent thrust vector control system test
NASA Technical Reports Server (NTRS)
2008-01-01
Testing of the Ascent Thrust Vector Control System in support of the Ares 1-X program at the Marshall Space Flight Center in Huntsville, Alabama. This image is extracted from a high definition video file and is the highest resolution available
Bethe vectors for XXX-spin chain
NASA Astrophysics Data System (ADS)
Burdík, Čestmír; Fuksa, Jan; Isaev, Alexei
2014-11-01
The paper deals with algebraic Bethe ansatz for XXX-spin chain. Generators of Yang-Baxter algebra are expressed in basis of free fermions and used to calculate explicit form of Bethe vectors. Their relation to N-component models is used to prove conjecture about their form in general. Some remarks on inhomogeneous XXX-spin chain are included.
A Lesson in Vectors "Plain" and Simple
ERIC Educational Resources Information Center
Bradshaw, David M.
2004-01-01
The United States Military Academy (USMA) has a four course core mathematics curriculum that is studied by all students. The third course is MA205, Calculus II; a multivariate calculus course filled with practical applications. During a Problem Solving Lab (PSL), students participated in a hands-on exercise with multiple vector operations,…
Image compression using address-vector quantization
NASA Astrophysics Data System (ADS)
Nasrabadi, Nasser M.; Feng, Yushu
1990-12-01
A novel vector quantization scheme, the address-vector quantizer (A-VQ), is proposed which exploits the interblock correlation by encoding a group of blocks together using an address-codebook (AC). The AC is a set of address-codevectors (ACVs), each representing a combination of addresses or indices. Each element of the ACV is an address of an entry in the LBG-codebook, representing a vector-quantized block. The AC consists of an active (addressable) region and an inactive (nonaddressable) region. During encoding the ACVs in the AC are reordered adaptively to bring the most probable ACVs into the active region. When encoding an ACV, the active region is checked, and if such an address combination exists, its index is transmitted to the receiver. Otherwise, the address of each block is transmitted individually. The SNR of the images encoded by the A-VQ method is the same as that of a memoryless vector quantizer, but the bit rate is by a factor of approximately two.
System for Automated Calibration of Vector Modulators
NASA Technical Reports Server (NTRS)
Lux, James; Boas, Amy; Li, Samuel
2009-01-01
Vector modulators are used to impose baseband modulation on RF signals, but non-ideal behavior limits the overall performance. The non-ideal behavior of the vector modulator is compensated using data collected with the use of an automated test system driven by a LabVIEW program that systematically applies thousands of control-signal values to the device under test and collects RF measurement data. The technology innovation automates several steps in the process. First, an automated test system, using computer controlled digital-to-analog converters (DACs) and a computer-controlled vector network analyzer (VNA) systematically can apply different I and Q signals (which represent the complex number by which the RF signal is multiplied) to the vector modulator under test (VMUT), while measuring the RF performance specifically, gain and phase. The automated test system uses the LabVIEW software to control the test equipment, collect the data, and write it to a file. The input to the Lab - VIEW program is either user-input for systematic variation, or is provided in a file containing specific test values that should be fed to the VMUT. The output file contains both the control signals and the measured data. The second step is to post-process the file to determine the correction functions as needed. The result of the entire process is a tabular representation, which allows translation of a desired I/Q value to the required analog control signals to produce a particular RF behavior. In some applications, corrected performance is needed only for a limited range. If the vector modulator is being used as a phase shifter, there is only a need to correct I and Q values that represent points on a circle, not the entire plane. This innovation has been used to calibrate 2-GHz MMIC (monolithic microwave integrated circuit) vector modulators in the High EIRP Cluster Array project (EIRP is high effective isotropic radiated power). These calibrations were then used to create
Automated image segmentation using support vector machines
NASA Astrophysics Data System (ADS)
Powell, Stephanie; Magnotta, Vincent A.; Andreasen, Nancy C.
2007-03-01
Neurodegenerative and neurodevelopmental diseases demonstrate problems associated with brain maturation and aging. Automated methods to delineate brain structures of interest are required to analyze large amounts of imaging data like that being collected in several on going multi-center studies. We have previously reported on using artificial neural networks (ANN) to define subcortical brain structures including the thalamus (0.88), caudate (0.85) and the putamen (0.81). In this work, apriori probability information was generated using Thirion's demons registration algorithm. The input vector consisted of apriori probability, spherical coordinates, and an iris of surrounding signal intensity values. We have applied the support vector machine (SVM) machine learning algorithm to automatically segment subcortical and cerebellar regions using the same input vector information. SVM architecture was derived from the ANN framework. Training was completed using a radial-basis function kernel with gamma equal to 5.5. Training was performed using 15,000 vectors collected from 15 training images in approximately 10 minutes. The resulting support vectors were applied to delineate 10 images not part of the training set. Relative overlap calculated for the subcortical structures was 0.87 for the thalamus, 0.84 for the caudate, 0.84 for the putamen, and 0.72 for the hippocampus. Relative overlap for the cerebellar lobes ranged from 0.76 to 0.86. The reliability of the SVM based algorithm was similar to the inter-rater reliability between manual raters and can be achieved without rater intervention.
Data Analysis for the SOLIS Vector Spectromagnetograph
NASA Technical Reports Server (NTRS)
Jones, Harrison P.; Harvey, John W.; Oegerle, William (Technical Monitor)
2002-01-01
The National Solar Observatory's SOLIS Vector Spectromagnetograph (VSM), which will produce three or more full-disk maps of the Sun's photospheric vector magnetic field every day for at least one solar magnetic cycle, is in the final stages of assembly. Initial observations, including cross-calibration with the current NASA/NSO spectromagnetograph (SPM) will soon be carried out at a test site in Tucson. This paper discusses data analysis techniques for reducing the raw data, calculation of line-of-sight magnetograms and both quick-look and high-precision inference of vector fields from Stokes spectral profiles. Existing SPM algorithms, suitably modified to accomodate the cameras, scanning pattern, and polarization calibration optics for the VSM, will be used to "clean" the raw data and to process line-of-sight, magnetograms. A recent. version of the High Altitude Observatory Milne-Eddington (HAO-ME) inversion code (Skumanich and Lites; 1987, 11)J 322, p. 473) will he used for high-precision vector fields since the algorithm has been extensively tested, is well understood, and is fast enough to complete data analysis within 24 hours of data acquisition. The simplified inversion algorithm of Auer, Heasley. arid House (1977, Sol. Phys. 55, p. 47) forms the initial guess for this version of the HAO-ME code and will be used for quick-look vector analysis of VSM data since its performance on simulated Stokes profiles is better than other candidate methods. Improvements (e.g., principal components analysis or neural networks) are under consideration and will be straightforward to implement. However, current resources are sufficient to store the original Stokes profiles only long enough for high-precision analysis. Retrospective reduction of Stokes data with improved methods will not be possible, and modifications will only be introduced when the advantages of doing so are compelling enough to justify discontinuity in the long-term data stream.
Electromagnetic couplings of elementary vector particles
Napsuciale, M.; Rodriguez, S.; Delgado-Acosta, E. G.; Kirchbach, M.
2008-01-01
On the basis of the three fundamental principles of (i) Poincare symmetry of space-time, (ii) electromagnetic gauge symmetry, and (iii) unitarity, we construct an universal Lagrangian for the electromagnetic interactions of elementary vector particles, i.e., massive spin-1 particles transforming in the ((1/2),(1/2)) representation space of the homogeneous Lorentz group. We make the point that the first two symmetries alone do not fix the electromagnetic couplings uniquely but solely prescribe a general Lagrangian depending on two free parameters, here denoted by {xi} and g. The first one defines the electric-dipole and the magnetic-quadrupole moments of the vector particle, while the second determines its magnetic-dipole and electric-quadrupole moments. In order to fix the parameters one needs an additional physical input suited for the implementation of the third principle. As such, one chooses Compton scattering off a vector target and requires the cross section to respect the unitarity bounds in the high-energy limit. As a result, we obtain the universal g=2 and {xi}=0 values which completely characterize the electromagnetic couplings of the considered elementary vector field at tree level. The nature of this vector particle, Abelian versus non-Abelian, does not affect this structure. Merely, a partition of the g=2 value into non-Abelian, g{sub na}, and Abelian, g{sub a}=2-g{sub na}, contributions occurs for non-Abelian fields with the size of g{sub na} being determined by the specific non-Abelian group appearing in the theory of interest, be it the standard model or any other theory.
Chromatography purification of canine adenoviral vectors.
Segura, María Mercedes; Puig, Meritxell; Monfar, Mercè; Chillón, Miguel
2012-06-01
Canine adenovirus vectors (CAV2) are currently being evaluated for gene therapy, oncolytic virotherapy, and as vectors for recombinant vaccines. Despite the need for increasing volumes of purified CAV2 preparations for preclinical and clinical testing, their purification still relies on the use of conventional, scale-limited CsCl ultracentrifugation techniques. A complete downstream processing strategy for CAV2 vectors based on membrane filtration and chromatography is reported here. Microfiltration and ultra/diafiltration are selected for clarification and concentration of crude viral stocks containing both intracellular and extracellular CAV2 particles. A DNase digestion step is introduced between ultrafiltration and diafiltration operations. At these early stages, concentration of vector stocks with good recovery of viral particles (above 80%) and removal of a substantial amount of protein and nucleic acid contaminants is achieved. The ability of various chromatography techniques to isolate CAV2 particles was evaluated. Hydrophobic interaction chromatography using a Fractogel propyl tentacle resin was selected as a first chromatography step, because it allows removal of the bulk of contaminating proteins with high CAV2 yields (88%). An anion-exchange chromatography step using monolithic supports is further introduced to remove the remaining contaminants with good recovery of CAV2 particles (58-69%). The main CAV2 viral structural components are visualized in purified preparations by electrophoresis analyses. Purified vector stocks contained intact icosahedral viral particles, low contamination with empty viral capsids (10%), and an acceptable total-to-infectious particle ratio (below 30). The downstream processing strategy that was developed allows preparation of large volumes of high-quality CAV2 stocks.
Perturbations of ultralight vector field dark matter
NASA Astrophysics Data System (ADS)
Cembranos, J. A. R.; Maroto, A. L.; Núñez Jareño, S. J.
2017-02-01
We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with {k}^2≪ Hma, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with {k}^2≫ Hma, we get a wave-like behaviour in which the sound speed is non-vanishing and of order c s 2 ≃ k 2/ m 2 a 2. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order ( Φ - Ψ)/ Φ ˜ c s 2 . Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also h/ Φ ˜ c s 2 . This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.
I-vectors for image classification
NASA Astrophysics Data System (ADS)
Smith, David C.
2014-09-01
Recent state-of-the-art work on speaker recognition and verification uses a simple factor analysis to derive a low-dimensional total variability space" which simultaneously captures speaker and channel variability. This approach simplified earlier work using joint factor analysis to separately model speaker and channel differences. Here we adapt this "i-vector" method to image classification by replacing speakers with image categories, voice cuts with images, and cepstral features with SURF local descriptors, and where the role of channel variability is attributed to differences in image backgrounds or lighting conditions. A Universal Gaussian mixture model (UGMM) is trained (unsupervised) on SURF descriptors extracted from a varied and extensive image corpus. Individual images are modeled by additively perturbing the supervector of stacked means of this UGMM by the product of a low-rank total variability matrix (TVM) and a normally distributed hidden random vector, X. The TVM is learned by applying an EM algorithm to maximize the sum of log-likelihoods of descriptors extracted from training images, where the likelihoods are computed with respect to the GMM obtained by perturbing the UGMM means via the TVM as above, and leaving UGMM covariances unchanged. Finally, the low-dimensional i-vector representation of an image is the expected value of the posterior distribution of X conditioned on the image's descriptors, and is computed via straightforward matrix manipulations involving the TVM and image-specific Baum-Welch statistics. We compare classification rates found with (i) i-vectors (ii) PCA (iii) Discriminant Attribute Projection (the last two trained on Gaussian MAP-adapted supervector image representations), and (iv) replacing the TVM with the matrix of dominant PCA eigenvectors before i-vector extraction.
Data Analysis for the SOLIS Vector Spectromagnetograph
NASA Technical Reports Server (NTRS)
Jones, Harrison P.; Harvey, John W.; Oegerle, William (Technical Monitor)
2002-01-01
The National Solar Observatory's SOLIS Vector Spectromagnetograph (VSM), which will produce three or more full-disk maps of the Sun's photospheric vector magnetic field every day for at least one solar magnetic cycle, is in the final stages of assembly. Initial observations, including cross-calibration with the current NASA/NSO spectromagnetograph (SPM) will soon be carried out at a test site in Tucson. This paper discusses data analysis techniques for reducing the raw data, calculation of line-of-sight magnetograms and both quick-look and high-precision inference of vector fields from Stokes spectral profiles. Existing SPM algorithms, suitably modified to accomodate the cameras, scanning pattern, and polarization calibration optics for the VSM, will be used to "clean" the raw data and to process line-of-sight, magnetograms. A recent. version of the High Altitude Observatory Milne-Eddington (HAO-ME) inversion code (Skumanich and Lites; 1987, 11)J 322, p. 473) will he used for high-precision vector fields since the algorithm has been extensively tested, is well understood, and is fast enough to complete data analysis within 24 hours of data acquisition. The simplified inversion algorithm of Auer, Heasley. arid House (1977, Sol. Phys. 55, p. 47) forms the initial guess for this version of the HAO-ME code and will be used for quick-look vector analysis of VSM data since its performance on simulated Stokes profiles is better than other candidate methods. Improvements (e.g., principal components analysis or neural networks) are under consideration and will be straightforward to implement. However, current resources are sufficient to store the original Stokes profiles only long enough for high-precision analysis. Retrospective reduction of Stokes data with improved methods will not be possible, and modifications will only be introduced when the advantages of doing so are compelling enough to justify discontinuity in the long-term data stream.
Switching non-local vector median filter
NASA Astrophysics Data System (ADS)
Matsuoka, Jyohei; Koga, Takanori; Suetake, Noriaki; Uchino, Eiji
2016-04-01
This paper describes a novel image filtering method that removes random-valued impulse noise superimposed on a natural color image. In impulse noise removal, it is essential to employ a switching-type filtering method, as used in the well-known switching median filter, to preserve the detail of an original image with good quality. In color image filtering, it is generally preferable to deal with the red (R), green (G), and blue (B) components of each pixel of a color image as elements of a vectorized signal, as in the well-known vector median filter, rather than as component-wise signals to prevent a color shift after filtering. By taking these fundamentals into consideration, we propose a switching-type vector median filter with non-local processing that mainly consists of a noise detector and a noise removal filter. Concretely, we propose a noise detector that proactively detects noise-corrupted pixels by focusing attention on the isolation tendencies of pixels of interest not in an input image but in difference images between RGB components. Furthermore, as the noise removal filter, we propose an extended version of the non-local median filter, we proposed previously for grayscale image processing, named the non-local vector median filter, which is designed for color image processing. The proposed method realizes a superior balance between the preservation of detail and impulse noise removal by proactive noise detection and non-local switching vector median filtering, respectively. The effectiveness and validity of the proposed method are verified in a series of experiments using natural color images.
Vector-Mediated In Vivo Antibody Expression.
Schnepp, Bruce C; Johnson, Philip R
2014-08-01
This article focuses on a novel vaccine strategy known as vector-mediated antibody gene transfer, with a particular focus on human immunodeficiency virus (HIV). This strategy provides a solution to the problem of current vaccines that fail to generate neutralizing antibodies to prevent HIV-1 infection and AIDS. Antibody gene transfer allows for predetermination of antibody affinity and specificity prior to "immunization" and avoids the need for an active humoral immune response against the HIV envelope protein. This approach uses recombinant adeno-associated viral (rAAV) vectors, which have been shown to transduce muscle with high efficiency and direct the long-term expression of a variety of transgenes, to deliver the gene encoding a broadly neutralizing antibody into the muscle. Following rAAV vector gene delivery, the broadly neutralizing antibodies are endogenously synthesized in myofibers and passively distributed to the circulatory system. This is an improvement over classical passive immunization strategies that administer antibody proteins to the host to provide protection from infection. Vector-mediated gene transfer studies in mice and monkeys with anti-HIV and simian immunodeficiency virus (SIV)-neutralizing antibodies demonstrated long-lasting neutralizing activity in serum with complete protection against intravenous challenge with virulent HIV and SIV. These results indicate that existing potent anti-HIV antibodies can be rapidly moved into the clinic. However, this methodology need not be confined to HIV. The general strategy of vector-mediated antibody gene transfer can be applied to other difficult vaccine targets such as hepatitis C virus, malaria, respiratory syncytial virus, and tuberculosis.
Ahn, Miwon; Gamble, Aisha; Witting, Scott R.; Magrisso, Jack; Surendran, Sneha; Obici, Silvana
2013-01-01
Abstract Helper-dependent adenoviral vectors (HD Ad) hold extreme promise for gene therapy of human diseases. All viral genes are deleted in HD Ad vectors, and therefore, the presence of a helper virus is required for their production. Current methods to minimize helper contamination in large-scale preparations rely on the use of the Cre/loxP system. The inclusion of loxP sites flanking the packaging signal results in its excision in the presence of Cre recombinase, preventing helper genome encapsidation. It is well established that the level of Cre recombinase activity is important in determining the degree of helper contamination. However, there is little information on other mechanisms that could also play an important role. We have generated several HD Ad vectors containing a rapalog-inducible system to regulate transgene expression, or LacZ under the control of the elongation factor 1 α promoter. Large-scale production of these vectors resulted in abundant helper contamination. Viral DNA analysis revealed the presence of rearrangements between vector and helper genomes. The rearrangements involved a helper DNA molecule with a fragment of the left arm of the HD Ad vector, including its ITR, packaging signal, and some stuffer sequence. Overall, our data suggest that helper DNA molecules that accumulate after Cre recombinase activity are prone to rearrangements, resulting in helper genomes that have incorporated a packaging signal from the vector. Helper particles with rearranged genomes have a growth advantage. This study identifies a novel mechanism leading to helper contamination during helper-dependent adenoviral vector production. PMID:23249343
Charmless Hadronic B Decays into Vector, Axial Vector and Tensor Final States at BaBar
Gandini, Paolo; /Milan U. /INFN, Milan
2012-04-06
We present experimental measurements of branching fraction and longitudinal polarization fraction in charmless hadronic B decays into vector, axial vector and tensor final states with the final dataset of BABAR. Measurements of such kind of decays are a powerful tool both to test the Standard Model and search possible sources of new physics. In this document we present a short review of the last experimental results at BABAR concerning charmless quasi two-body decays in final states containing particles with spin 1 or spin 2 and different parities. This kind of decays has received considerable theoretical interest in the last few years and this particular attention has led to interesting experimental results at the current b-factories. In fact, the study of longitudinal polarization fraction f{sub L} in charmless B decays to vector vector (VV), vector axial-vector (VA) and axial-vector axial-vector (AA) mesons provides information on the underlying helicity structure of the decay mechanism. Naive helicity conservation arguments predict a dominant longitudinal polarization fraction f{sub L} {approx} 1 for both tree and penguin dominated decays and this pattern seems to be confirmed by tree-dominated B {yields} {rho}{rho} and B{sup +} {yields} {Omega}{rho}{sup +} decays. Other penguin dominated decays, instead, show a different behavior: the measured value of f{sub L} {approx} 0.5 in B {yields} {phi}K* decays is in contrast with naive Standard Model (SM) calculations. Several solutions have been proposed such as the introduction of non-factorizable terms and penguin-annihilation amplitudes, while other explanations invoke new physics. New modes have been investigated to shed more light on the problem.
Feature clustering in direct eigen-vector data reduction using support vector machines
NASA Astrophysics Data System (ADS)
Riasati, Vahid R.; Gao, Wenhue
2012-06-01
Principal Component Analysis (PCA) has been used in a variety of applications like feature extraction for classification, data compression and dimensionality reduction. Often, a small set of principal components are sufficient to capture the largest variations in the data. As a result, the eigen-values of the data covariance matrix with the lowest magnitude are ignored (along with their corresponding eigen-vectors) and the remaining eigenvectors are used for a 'coarse' representation of the data. It is well known that this process of choosing a few principal components naturally induces a loss in information from a signal reconstruction standpoint. We propose a new technique to represent the data in terms of a new set of basis vectors where the high-frequency detail is preserved, at the expense of a 'feature-scale blurring'. In other words, the 'blurring' that occurs due to possible colinearities in the bases vectors is relative to the eigen-features' scales; this is inherently different from a systematic blurring function. Instead of thresholding the eigen-values, we retain all eigen-values, and apply thresholds on the components of each eigen-vector separately. The resulting basis vectors can no longer be interpreted as eigenvectors and will, in general, lose their orthogonality properties, but offer benefits in terms of preserving detail that is crucial for classification tasks. We test the merits of this new basis representation for magnitude synthetic aperture radar (SAR) Automatic Target Recognition (ATR). A feature vector is obtained by projecting a SAR image onto the aforementioned basis. Decision engines such as support vector machines (SVMs) are trained on example feature vectors per class and ultimately used to recognize the target class in real-time. Experimental validation are performed on the MSTAR database and involve comparisons against a PCA based ATR algorithm.
Vector adaptive predictive coder for speech and audio
NASA Technical Reports Server (NTRS)
Chen, Juin-Hwey (Inventor); Gersho, Allen (Inventor)
1990-01-01
A real-time vector adaptive predictive coder which approximates each vector of K speech samples by using each of M fixed vectors in a first codebook to excite a time-varying synthesis filter and picking the vector that minimizes distortion. Predictive analysis for each frame determines parameters used for computing from vectors in the first codebook zero-state response vectors that are stored at the same address (index) in a second codebook. Encoding of input speech vectors s.sub.n is then carried out using the second codebook. When the vector that minimizes distortion is found, its index is transmitted to a decoder which has a codebook identical to the first codebook of the decoder. There the index is used to read out a vector that is used to synthesize an output speech vector s.sub.n. The parameters used in the encoder are quantized, for example by using a table, and the indices are transmitted to the decoder where they are decoded to specify transfer characteristics of filters used in producing the vector s.sub.n from the receiver codebook vector selected by the vector index transmitted.
Reciprocity relationships in vector acoustics and their application to vector field calculations.
Deal, Thomas J; Smith, Kevin B
2017-08-01
The reciprocity equation commonly stated in underwater acoustics relates pressure fields and monopole sources. It is often used to predict the pressure measured by a hydrophone for multiple source locations by placing a source at the hydrophone location and calculating the field everywhere for that source. A similar equation that governs the orthogonal components of the particle velocity field is needed to enable this computational method to be used for acoustic vector sensors. This paper derives a general reciprocity equation that accounts for both monopole and dipole sources. This vector-scalar reciprocity equation can be used to calculate individual components of the received vector field by altering the source type used in the propagation calculation. This enables a propagation model to calculate the received vector field components for an arbitrary number of source locations with a single model run for each vector field component instead of requiring one model run for each source location. Application of the vector-scalar reciprocity principle is demonstrated with analytic solutions for a range-independent environment and with numerical solutions for a range-dependent environment using a parabolic equation model.
HSV-1 amplicon peptide display vector.
Spear, Matthew A; Schuback, Deborah; Miyata, Kenichi; Grandi, Paola; Sun, Fang; Yoo, Linda; Nguyen, Anh; Brandt, Curtis R; Breakefield, Xandra O
2003-01-01
There are significant uses for expressing foreign peptide epitopes in viral surface attachment proteins in terms of investigating viral targeting, biology, and immunology. HSV-1 attachment, followed by fusion and entry, is mediated in large part by the binding of viral surface glycoproteins to cell surface receptors, primarily through heparan sulfate (HS) glycosaminoglycan residues. We constructed a HSV-1 amplicon plasmid (pCONGA) carrying the gC primary attachment protein gene with unique restriction sites flanking the HS binding domain (HSBD) (residues 33-176) to allow rapid, high efficiency substitution with foreign peptide domains. To test this system, a His tag with an additional unique restriction site (for selection and assay digests) was recombined into the pCONGA HSBD site to create pCONGAH. Infection of pCONGAH transfected Vero cells with HSV-1 helper virus (gCdelta2-3 or hrR3) produced His-modified gC as demonstrated by western blot analysis with co-localization of anti-gC and anti-His tag antibodies to a protein of appropriate molecular weight (50 kd). As CONGA and CONGAH amplicons carry a GFP transgene and the gCdelta2-3 and hrR3 viruses carry a lacZ transgene, vector stocks produced from 1 x 10(5) Vero cells could be titered for competent vector on cell monolayers and were demonstrated to contain 2 x 10(5) amplicon vector transducing units (t.u.)/ml and 1 x 10(7) virus t.u./ml. As the amplicon plasmids also contain the neomycin resistance gene (neo(r)), long term vector producer cell lines were created using G418 selection. This amplicon system provides means to rapidly and efficiently generate HSV-1 amplicon and viral vector expressing surface attachment proteins modified with different peptide epitopes for investigational and therapeutic uses, with the advantages of an amplicon plasmid that can be used with interchangeable helper virus vectors, is designed specifically for easy manipulation, and carries GFP and neo(r) transgenes for marker and
Construction and Evaluation of Novel Rhesus Monkey Adenovirus Vaccine Vectors
Abbink, Peter; Maxfield, Lori F.; Ng'ang'a, David; Borducchi, Erica N.; Iampietro, M. Justin; Bricault, Christine A.; Teigler, Jeffrey E.; Blackmore, Stephen; Parenteau, Lily; Wagh, Kshitij; Handley, Scott A.; Zhao, Guoyan; Virgin, Herbert W.; Korber, Bette; Barouch, Dan H.
2014-11-19
Adenovirus vectors are widely used as vaccine candidates for a variety of pathogens, including HIV-1. To date, human and chimpanzee adenoviruses have been explored in detail as vaccine vectors. Furthermore, the phylogeny of human and chimpanzee adenoviruses is overlapping, and preexisting humoral and cellular immunity to both are exhibited in human populations worldwide. More distantly related adenoviruses may therefore offer advantages as vaccine vectors. We describe the primary isolation and vectorization of three novel adenoviruses from rhesus monkeys. The seroprevalence of these novel rhesus monkey adenovirus vectors was extremely low in sub-Saharan Africa human populations, and these vectors proved to have immunogenicity comparable to that of human and chimpanzee adenovirus vaccine vectors in mice. These rhesus monkey adenoviruses phylogenetically clustered with the poorly described adenovirus species G and robustly stimulated innate immune responses. These novel adenoviruses represent a new class of candidate vaccine vectors.
Construction and Evaluation of Novel Rhesus Monkey Adenovirus Vaccine Vectors
Abbink, Peter; Maxfield, Lori F.; Ng'ang'a, David; ...
2014-11-19
Adenovirus vectors are widely used as vaccine candidates for a variety of pathogens, including HIV-1. To date, human and chimpanzee adenoviruses have been explored in detail as vaccine vectors. Furthermore, the phylogeny of human and chimpanzee adenoviruses is overlapping, and preexisting humoral and cellular immunity to both are exhibited in human populations worldwide. More distantly related adenoviruses may therefore offer advantages as vaccine vectors. We describe the primary isolation and vectorization of three novel adenoviruses from rhesus monkeys. The seroprevalence of these novel rhesus monkey adenovirus vectors was extremely low in sub-Saharan Africa human populations, and these vectors proved tomore » have immunogenicity comparable to that of human and chimpanzee adenovirus vaccine vectors in mice. These rhesus monkey adenoviruses phylogenetically clustered with the poorly described adenovirus species G and robustly stimulated innate immune responses. These novel adenoviruses represent a new class of candidate vaccine vectors.« less
Support of the extremal measure in a vector equilibrium problem
NASA Astrophysics Data System (ADS)
Lapik, M. A.
2006-08-01
A generalization of the Mhaskar-Saff functional is obtained for a vector equilibrium problem with an external field. As an application, the supports of the equilibrium measures are found in a special vector equilibrium problem with Nikishin matrix.
Orbits of Two-Body Problem From the Lenz Vector
ERIC Educational Resources Information Center
Caplan, S.; And Others
1978-01-01
Obtains the orbits with reference to the center of mass of two bodies under mutual universe square law interaction by use of the eccentricity vector which is equivalent to the Lenz vector within a numerical factor. (Author/SL)
Modification of pIX or hexon based on fiberless Ad vectors is not effective for targeted Ad vectors.
Kurachi, Shinnosuke; Koizumi, Naoya; Tashiro, Katsuhisa; Sakurai, Haruna; Sakurai, Fuminori; Kawabata, Kenji; Nakagawa, Shinsaku; Mizuguchi, Hiroyuki
2008-04-07
Adenovirus (Ad) vector application in gene therapy is limited by its naïve tropism. We previously developed protein IX (pIX)-modified and hexon-modified Ad vectors in order to alter Ad vector tropism. However, these modified Ad vectors failed to infect cells with the foreign ligands displayed in the pIX or hexon. We hypothesized that steric hindrance by fiber proteins might have prevented the ligand-mediated transduction, as fibers are the outmost capsid proteins of Ad vectors. Therefore, we generated a series of fiberless Ad vectors and investigated their gene expression properties. Unexpectively, however, pIX- or hexon-modified fiberless Ad vector did not achieve any gene expression (the gene expression level by these vectors was similar to the background level). These results might be caused by the fact that the fiberless particles were weaker against physical burdens. To the best of our knowledge, this study is the first reported attempt to develop fiberless Ad vectors containing foreign ligands in the pIX or hexon region. The drawback of the lower stability of fiberless Ad vectors must be overcome to develop targeted Ad vectors based on such vectors. This study could provide basic information for the development of effective targeted Ad vectors.
Students' Responses To Different Representations Of A Vector Addition Question
NASA Astrophysics Data System (ADS)
Hawkins, Jeffrey M.; Thompson, John R.; Wittmann, Michael C.; Sayre, Eleanor C.; Frank, Brian W.
2010-10-01
We investigate if the visual representation of vectors can affect which methods students use to add them. We gave students one of four questions with different graphical representations, asking students to add the same two vectors. For students in an algebra-based class the arrangement of the vectors had a statistically significant effect on the vector addition method chosen while the addition or removal of a grid did not.
All-optical vector atomic magnetometer.
Patton, B; Zhivun, E; Hovde, D C; Budker, D
2014-07-04
We demonstrate an all-optical magnetometer capable of measuring the magnitude and direction of a magnetic field using nonlinear magneto-optical rotation in cesium vapor. Vector capability is added by effective modulation of the field along orthogonal axes and subsequent demodulation of the magnetic-resonance frequency. This modulation is provided by the ac Stark shift induced by circularly polarized laser beams. The sensor exhibits a demonstrated rms noise floor of ∼65 fT/√[Hz] in measurement of the field magnitude and 0.5 mrad/√[Hz] in the field direction; elimination of technical noise would improve these sensitivities to 12 fT/√[Hz] and 10 μrad/√[Hz], respectively. Applications for this all-optical vector magnetometer would include magnetically sensitive fundamental physics experiments, such as the search for a permanent electric dipole moment of the neutron.
MAGSAT: Vector magnetometer absolute sensor alignment determination
NASA Technical Reports Server (NTRS)
Acuna, M. H.
1981-01-01
A procedure is described for accurately determining the absolute alignment of the magnetic axes of a triaxial magnetometer sensor with respect to an external, fixed, reference coordinate system. The method does not require that the magnetic field vector orientation, as generated by a triaxial calibration coil system, be known to better than a few degrees from its true position, and minimizes the number of positions through which a sensor assembly must be rotated to obtain a solution. Computer simulations show that accuracies of better than 0.4 seconds of arc can be achieved under typical test conditions associated with existing magnetic test facilities. The basic approach is similar in nature to that presented by McPherron and Snare (1978) except that only three sensor positions are required and the system of equations to be solved is considerably simplified. Applications of the method to the case of the MAGSAT Vector Magnetometer are presented and the problems encountered discussed.
In situ vector calibration of magnetic observatories
NASA Astrophysics Data System (ADS)
Gonsette, Alexandre; Rasson, Jean; Humbled, François
2017-09-01
The goal of magnetic observatories is to measure and provide a vector magnetic field in a geodetic coordinate system. For that purpose, instrument set-up and calibration are crucial. In particular, the scale factor and orientation of a vector magnetometer may affect the magnetic field measurement. Here, we highlight the baseline concept and demonstrate that it is essential for data quality control. We show how the baselines can highlight a possible calibration error. We also provide a calibration method based on high-frequency absolute measurements
. This method determines a transformation matrix for correcting variometer data suffering from scale factor and orientation errors. We finally present a practical case where recovered data have been successfully compared to those coming from a reference magnetometer.
Canine vector-borne diseases in Brazil
Dantas-Torres, Filipe
2008-01-01
Canine vector-borne diseases (CVBDs) are highly prevalent in Brazil and represent a challenge to veterinarians and public health workers, since some diseases are of great zoonotic potential. Dogs are affected by many protozoa (e.g., Babesia vogeli, Leishmania infantum, and Trypanosoma cruzi), bacteria (e.g., Anaplasma platys and Ehrlichia canis), and helminths (e.g., Dirofilaria immitis and Dipylidium caninum) that are transmitted by a diverse range of arthropod vectors, including ticks, fleas, lice, triatomines, mosquitoes, tabanids, and phlebotomine sand flies. This article focuses on several aspects (etiology, transmission, distribution, prevalence, risk factors, diagnosis, control, prevention, and public health significance) of CVBDs in Brazil and discusses research gaps to be addressed in future studies. PMID:18691408
Genetically engineering adenoviral vectors for gene therapy.
Coughlan, Lynda
2014-01-01
Adenoviral (Ad) vectors are commonly used for various gene therapy applications. Significant advances in the genetic engineering of Ad vectors in recent years has highlighted their potential for the treatment of metastatic disease. There are several methods to genetically modify the Ad genome to incorporate retargeting peptides which will redirect the natural tropism of the viruses, including homologous recombination in bacteria or yeast. However, homologous recombination in yeast is highly efficient and can be achieved without the need for extensive cloning strategies. In addition, the method does not rely on the presence of unique restriction sites within the Ad genome and the reagents required for this method are widely available and inexpensive. Large plasmids containing the entire adenoviral genome (~36 kbp) can be modified within Saccharomyces cerevisiae yeast and genomes easily rescued in Escherichia coli hosts for analysis or amplification. A method for two-step homologous recombination in yeast is described in this chapter.
Support vector machine for automatic pain recognition
NASA Astrophysics Data System (ADS)
Monwar, Md Maruf; Rezaei, Siamak
2009-02-01
Facial expressions are a key index of emotion and the interpretation of such expressions of emotion is critical to everyday social functioning. In this paper, we present an efficient video analysis technique for recognition of a specific expression, pain, from human faces. We employ an automatic face detector which detects face from the stored video frame using skin color modeling technique. For pain recognition, location and shape features of the detected faces are computed. These features are then used as inputs to a support vector machine (SVM) for classification. We compare the results with neural network based and eigenimage based automatic pain recognition systems. The experiment results indicate that using support vector machine as classifier can certainly improve the performance of automatic pain recognition system.
The vector structure of active magnetic fields
NASA Technical Reports Server (NTRS)
Parker, E. N.
1985-01-01
Observations are needed to show the form of the strains introduced into the fields above the surface of the Sun. The longitudinal component alone does not provide the basic information, so that it has been necessary in the past to use the filamentary structure observed in H sub alpha to supplement the longitudinal information. Vector measurements provide the additional essential information to determine the strains, with the filamentary structure available as a check for consistency. It is to be expected, then, that vector measurements will permit a direct mapping of the strains imposed on the magnetic fields of active regions. It will be interesting to study the relation of those strains to the emergence of magnetic flux, flares, eruptive prominences, etc. In particular we may hope to study the relaxation of the strains via the dynamical nonequilibrium.
Light Vector Mesons in the Nuclear Medium
Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis; Djalali, Chaden; Tur, Clarisse; Mosel, Ulrich; Muehlich, Pascal; Adams, Gary; Amaryan, Moscov; Amaryan, Moskov; Ambrozewicz, Pawel; Anghinolfi, Marco; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, James; Baltzell, Nathan; Barrow, Steve; Battaglieri, Marco; Bedlinskiy, Ivan; Bektasoglu, Mehmet; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Biselli, Angela; Blaszczyk, Lukasz; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Carnahan, Bryan; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crannell, Hall; Crede, Volker; Cummings, John; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Denizli, Haluk; Dennis, Lawrence; Deur, Alexandre; Dharmawardane, Kahanawita; Dickson, Richard; Dodge, Gail; Doughty, David; Dugger, Michael; Dytman, Steven; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feldman, Gerald; Feuerbach, Robert; Fradi, Ahmed; Funsten, Herbert; Garcon, Michel; Gavalian, Gagik; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gordon, Christopher; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hadjidakis, Cynthia; Hafidi, Kawtar; Hakobyan, Hayk; Hakobyan, Rafael; Hanretty, Charles; Hardie, John; Hassall, Neil; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Klimenko, Alexei; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Li, Ji; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; McAleer, Simeon; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mehrabyan, Surik; Melone, Joseph; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Minehart, Ralph; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Mueller, James; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Preedom, Barry; Price, John; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Riccardi, Gregory; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Ronchetti, Federico; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Stepan; Stepanyan, Samuel; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Todor, Luminita; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Watts, Daniel; Weinstein, Lawrence; Williams, Michael; Wolin, Elliott; Yegneswaran, Amrit; Zana, Lorenzo; Zhang, Bin; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen
2008-07-01
The light vector mesons ($\\rho$, $\\omega$, and $\\phi$) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the $\\rho$ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The $\\rho$ meson mass spectrum was extracted after the $\\omega$ and $\\phi$ signals were removed in a nearly model-independent way. Comparisons were made between the $\\rho$ mass spectra from the heavy targets ($A > 2$) with the mass spectrum extracted from the deuterium target. With respect to the $\\rho$-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body eff
Approximate gauge symmetry of composite vector bosons
NASA Astrophysics Data System (ADS)
Suzuki, Mahiko
2010-08-01
It can be shown in a solvable field theory model that the couplings of the composite vector bosons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in a more intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.
Vector Magnetic Field in Emerging Flux Regions
NASA Astrophysics Data System (ADS)
Schmieder, B.; Pariat, E.
A crucial phase in magnetic flux emergence is the rise of magnetic flux tubes through the solar photosphere, which represents a severe transition between the very different environments of the solar interior and corona. Multi-wavelength observations with Flare Genesis, TRACE, SoHO, and more recently with the vector magnetographs at THEMIS and Hida (DST) led to the following conclusions. The fragmented magnetic field in the emergence region - with dipped field lines or bald patches - is directly related with Ellerman bombs, arch filament systems, and overlying coronal loops. Measurements of vector magnetic fields have given evidence that undulating "serpentine" fields are present while magnetic flux tubes cross the photosphere. See the sketch below, and for more detail see Pariat et al. (2004, 2007); Watanabe et al. (2008):
Lepton flavor violation with light vector bosons
NASA Astrophysics Data System (ADS)
Heeck, Julian
2016-07-01
New sub-GeV vector bosons with couplings to muons but not electrons have been discussed in order to explain the muon's magnetic moment, the gap of high-energy neutrinos in IceCube or the proton radius puzzle. If such a light Z‧ not only violates lepton universality but also lepton flavor, as expected for example from the recent hint for h → μτ at CMS, the two-body decay mode τ → μZ‧ opens up and for MZ‧ < 2mμ gives better constraints than τ → 3 μ already with 20-year-old ARGUS limits. We discuss the general prospects and motivation of light vector bosons with lepton-flavor-violating couplings.
Vector meson dominance and the {rho} meson
Benayoun, M.; OConnell, H.B.; Williams, A.G.
1999-04-01
We discuss the properties of vector mesons, in particular the {rho}{sup 0}, in the context of the hidden local symmetry (HLS) model. This provides a unified framework to study several aspects of the low energy QCD sector. First, we show that in the HLS model the physical photon is massless, without requiring off field diagonalization. We then demonstrate the equivalence of HLS and the two existing representations of vector meson dominance, VMD1 and VMD2, at both the tree level and one loop order. Finally the S matrix pole position is shown to provide a model and process independent means of specifying the {rho} mass and width, in contrast with the real axis prescription currently used in the Particle Data Group tables. {copyright} {ital 1999} {ital The American Physical Society}
Manipulating yeast genome using plasmid vectors.
Stearns, T; Ma, H; Botstein, D
1990-01-01
The vectors and techniques described here enable one to manipulate the yeast genome to meet specific needs. Genes can be cloned, and the clone used to delete the wild-type gene from the chromosome, or replace it with mutant versions. Mutants derived by classical methods, such as mutagenesis of whole cells, or by reversion of a phenotype, can be cloned and analyzed in vitro. Yeast genes and foreign genes can either be inserted into autonomously replicating plasmid vectors that are reasonably stable or integrated into a yeast chromosome where they are maintained at one copy per genome. The combination of these techniques with the characterized promoter systems available in yeast make it possible to express almost any gene in yeast. Once this is achieved, the entire repertoire of yeast genetics is available to probe the function of the gene, or to engineer the expression in useful ways.
Vector control activities: Fiscal Year, 1986
Not Available
1987-04-01
The program is divided into two major components - operations and support studies. The support studies are designed to improve the operational effectiveness and efficiency of the control program and to identify other vector control problems requiring TVA attention and study. Nonchemical methods of control are emphasized and are supplemented with chemical measures as needed. TVA also cooperates with various concerned municipalities in identifying blood-sucking arthropod pest problems and demonstrating control techniques useful in establishing abatement programs, and provides technical assistance to other TVA programs and organizations. The program also helps Land Between The Lakes (LBL) plan and conduct vector control operations and tick control research. Specific program control activities and support studies are discussed.
Classification of sparse high-dimensional vectors.
Ingster, Yuri I; Pouet, Christophe; Tsybakov, Alexandre B
2009-11-13
We study the problem of classification of d-dimensional vectors into two classes (one of which is 'pure noise') based on a training sample of size m. The main specific feature is that the dimension d can be very large. We suppose that the difference between the distribution of the population and that of the noise is only in a shift, which is a sparse vector. For Gaussian noise, fixed sample size m, and dimension d that tends to infinity, we obtain the sharp classification boundary, i.e. the necessary and sufficient conditions for the possibility of successful classification. We propose classifiers attaining this boundary. We also give extensions of the result to the case where the sample size m depends on d and satisfies the condition (log m)/log d --> gamma, 0
SIT for African malaria vectors: Epilogue
Townson, Harold
2009-01-01
As a result of increased support and the diligent application of new and conventional anti-malaria tools, significant reductions in malaria transmission are being accomplished. Historical and current evolutionary responses of vectors and parasites to malaria interventions demonstrate that it is unwise to assume that a limited suite of tools will remain effective indefinitely, thus efforts to develop new interventions should continue. This collection of manuscripts surveys the prospects and technical challenges for applying a novel tool, the sterile insect technique (SIT), against mosquitoes that transmit malaria. The method has been very successful against many agricultural pest insects in area-wide programs, but demonstrations against malaria vectors have not been sufficient to determine its potential relative to current alternatives, much of which will hinge ultimately upon cost. These manuscripts provide an overview of current efforts to develop SIT and identify key research issues that remain. PMID:19917071
Glueballs and vector mesons at NICA
NASA Astrophysics Data System (ADS)
Parganlija, Denis
2016-08-01
Two interconnected fields of interest are suggested for NICA. Firstly, existence of glueballs is predicted by the theory of strong interaction but --even after decades of research-- glueball identification in the physical spectrum is still unclear. NICA can help to ascertain experimental glueball candidates via J/Ψ decays whose yield is expected to be large. Importance of glueballs is not limited to vacuum: since they couple to other meson states, glueballs can also be expected to influence signatures of chiral-symmetry restoration in the high-energy phase of strong dynamics. Mass shifting or in-medium broadening of vector and axial-vector mesons may occur there but the extent of such phenomena is still uncertain. Additionally, glueball properties could also be modified in medium. Exploration of these issues is the second suggested field of interest that can be pursued at NICA.
Automated Vectorization of Decision-Based Algorithms
NASA Technical Reports Server (NTRS)
James, Mark
2006-01-01
Virtually all existing vectorization algorithms are designed to only analyze the numeric properties of an algorithm and distribute those elements across multiple processors. This advances the state of the practice because it is the only known system, at the time of this reporting, that takes high-level statements and analyzes them for their decision properties and converts them to a form that allows them to automatically be executed in parallel. The software takes a high-level source program that describes a complex decision- based condition and rewrites it as a disjunctive set of component Boolean relations that can then be executed in parallel. This is important because parallel architectures are becoming more commonplace in conventional systems and they have always been present in NASA flight systems. This technology allows one to take existing condition-based code and automatically vectorize it so it naturally decomposes across parallel architectures.
Satellite Angular Rate Estimation From Vector Measurements
NASA Technical Reports Server (NTRS)
Azor, Ruth; Bar-Itzhack, Itzhack Y.; Harman, Richard R.
1996-01-01
This paper presents an algorithm for estimating the angular rate vector of a satellite which is based on the time derivatives of vector measurements expressed in a reference and body coordinate. The computed derivatives are fed into a spacial Kalman filter which yields an estimate of the spacecraft angular velocity. The filter, named Extended Interlaced Kalman Filter (EIKF), is an extension of the Kalman filter which, although being linear, estimates the state of a nonlinear dynamic system. It consists of two or three parallel Kalman filters whose individual estimates are fed to one another and are considered as known inputs by the other parallel filter(s). The nonlinear dynamics stem from the nonlinear differential equation that describes the rotation of a three dimensional body. Initial results, using simulated data, and real Rossi X ray Timing Explorer (RXTE) data indicate that the algorithm is efficient and robust.
Holographic vector-wave femtosecond laser processing
NASA Astrophysics Data System (ADS)
Hayasaki, Yoshio; Hasegawa, Satoshi
2016-03-01
Arbitrary and variable beam shaping of femtosecond pulses by a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM) have been applied to femtosecond laser processing. The holographic femtosecond laser processing has been widely used in many applications such as two-photon polymerization, optical waveguide fabrication, fabrication of volume phase gratings in polymers, and surface nanostructuring. A vector wave that has a spatial distribution of polarization states control of femtosecond pulses gives good performances for the femtosecond laser processing. In this paper, an in- system optimization of a CGH for massively-parallel femtosecond laser processing, a dynamic control of spatial spectral dispersion to improve the focal spot shape, and the holographic vector-wave femtosecond laser processing are demonstrated.
Vectorized image segmentation via trixel agglomeration
Prasad, Lakshman; Skourikhine, Alexei N.
2006-10-24
A computer implemented method transforms an image comprised of pixels into a vectorized image specified by a plurality of polygons that can be subsequently used to aid in image processing and understanding. The pixelated image is processed to extract edge pixels that separate different colors and a constrained Delaunay triangulation of the edge pixels forms a plurality of triangles having edges that cover the pixelated image. A color for each one of the plurality of triangles is determined from the color pixels within each triangle. A filter is formed with a set of grouping rules related to features of the pixelated image and applied to the plurality of triangle edges to merge adjacent triangles consistent with the filter into polygons having a plurality of vertices. The pixelated image may be then reformed into an array of the polygons, that can be represented collectively and efficiently by standard vector image.
Fractional vector calculus and fractional Maxwell's equations
Tarasov, Vasily E.
2008-11-15
The theory of derivatives and integrals of non-integer order goes back to Leibniz, Liouville, Grunwald, Letnikov and Riemann. The history of fractional vector calculus (FVC) has only 10 years. The main approaches to formulate a FVC, which are used in the physics during the past few years, will be briefly described in this paper. We solve some problems of consistent formulations of FVC by using a fractional generalization of the Fundamental Theorem of Calculus. We define the differential and integral vector operations. The fractional Green's, Stokes' and Gauss's theorems are formulated. The proofs of these theorems are realized for simplest regions. A fractional generalization of exterior differential calculus of differential forms is discussed. Fractional nonlocal Maxwell's equations and the corresponding fractional wave equations are considered.
Vector mode analysis of a young interferometer.
Gori, Franco; Santarsiero, Massimo; Borghi, Riccardo
2006-04-01
It is proved that, when the vector modal theory of coherence is applied to a pair of fixed points, exact results are obtained for the mode structure. In particular, it is shown that the field radiated by the pinholes of a Young interferometer can always be represented by the incoherent superposition of no more than four perfectly correlated and polarized modes. The role of such modes is illustrated through a simple example.
Stabilized two-dimensional vector solitons.
Montesinos, Gaspar D; Pérez-García, Víctor M; Michinel, Humberto
2004-04-02
In this Letter, we introduce the concept of stabilized vector solitons as nonlinear waves constructed by the addition of mutually incoherent fractions of Townes solitons that are stabilized under the effect of a periodic modulation of the nonlinearity. We analyze the stability of these new kinds of structures and describe their behavior and formation in Manakov-like interactions. Potential applications of our results in Bose-Einstein condensation and nonlinear optics are also discussed.
Agriculture Canada Central Saskatchewan Vector Soils Data
NASA Technical Reports Server (NTRS)
Knapp, David; Hall, Forrest G. (Editor); Rostad, Harold
2000-01-01
This data set consists of GIS layers that describe the soils of the BOREAS SSA. These original data layers were submitted as vector data in ARC/INFO EXPORT format. These data also include the soil name and soil layer files, which provide additional information about the soils. There are three sets of attributes that include information on the primary, secondary, and tertiary soil type within each polygon. Thus, there is a total of nine main attributes in this data set.
Confidence regions of planar cardiac vectors
NASA Technical Reports Server (NTRS)
Dubin, S.; Herr, A.; Hunt, P.
1980-01-01
A method for plotting the confidence regions of vectorial data obtained in electrocardiology is presented. The 90%, 95% and 99% confidence regions of cardiac vectors represented in a plane are obtained in the form of an ellipse centered at coordinates corresponding to the means of a sample selected at random from a bivariate normal distribution. An example of such a plot for the frontal plane QRS mean electrical axis for 80 horses is also presented.
Regional Disease Vector Ecology Profile: The Koreas
2015-01-01
Epidemiology: Tick-borne Encephalitis (TBE) is a zoonotic viral infectious disease involving the central nervous system . In humans, the disease most...subsequently enter and multiply in the circulatory system of the louse. Lice are highly infective after 6 days and remain so for life (30-40 days...Regional Disease Vector Ecology Profile: The Koreas Published and Distributed by the Armed Forces Pest Management Board Information
A Vector Signal Processing Approach to Color
1992-01-01
AD-A259 499 Technical Report 1349 A Vector Signal Processing Approach to Color Kah-Kay Sun MIT Artificial Intelligence Laboratory DTIC S EELECTE JAN2...ADDRESS(ES) 8. PERFORMING ORGANIZATION Artificial Intelligence Laboratory REPORT NUMBER 545 Technology Square Cambridge, Massachusetts 02139 AIM 1349 9...report describes research done at the Artificial Intelligence Laboratory at MIT. This rc- search is sponsored by the Artificial Intelligence Center of
Minimum Time Turns Using Vectored Thrust.
1984-12-01
small, typicilly on the order of 10 seconds, the fuel consumed during the maneuver is negligible and the aircraft weight remains constant. The aircraft...practical (2, 3), these angles were allowed full range in order to determine how much range of thrust vectoring would be exploited if it were available...angle. 15q 15 *q 111. The Optimial Control Problem The formulation of the minimum turning time problem involves first- order non-linear differential
Problems of Automatic Vectorization of Artwork.
1987-01-01
relatively Inexpensive, vectorizatlon system compoeed of an IBM/XT, custom electronica hardware, and 300 DPI scanner. This report will summarize our...phllotoplotting. The Gerber photoplotting method, which continues to dominate this Industry , Involves the use of a wheel of apertures through which light...inspection currently being used in the printed wiring Industry . Artwork Inspection Is one of the desirable "spin-offs" of artwork vectorization. 4.1.1
System balance analysis for vector computers
NASA Technical Reports Server (NTRS)
Knight, J. C.; Poole, W. G., Jr.; Voight, R. G.
1975-01-01
The availability of vector processors capable of sustaining computing rates of 10 to the 8th power arithmetic results pers second raised the question of whether peripheral storage devices representing current technology can keep such processors supplied with data. By examining the solution of a large banded linear system on these computers, it was found that even under ideal conditions, the processors will frequently be waiting for problem data.
Acoustic Vector-Sensor Array Processing
2010-06-01
133 6.2 Future Work in VSA Processing . . . . . . . . . . . . . . . . . . . . . 135 A Supplemental Material 137 A.1 Symmetric Noise Distributions...nulls and widening the array response. The spatial spreading in Figure 2.4.1 is exag- gerated to illustrate its effects on the array response...resolution. 6.2 Future Work in VSA Processing The last chapter of this thesis is not the final chapter in vector-sensor array research. The doors opened
Vector Meson Property in Covariant Classification Scheme
NASA Astrophysics Data System (ADS)
Oda, Masuho
2004-08-01
Recently our collaboration group has proposed the covariant classification shceme of hadrons, leading to possible existence of two ground state vector mesons. One is corresponding to ordinary ρ nonet and the other is extra ρ nonet. We investigate the decay property of ω(1250) and ρ(1250) in the covariant classification scheme. And it is shown that ω(1250) is promising candidate of our extra ω meson.
Feedback Control Design for Counterflow Thrust Vectoring
2005-09-01
thrust vector angle. A model 27N pneumatic R-DDV servovalve from HR Textron is used in the test rig for this purpose. Data acquisition and control are...support this research. We also thank Robert Avant, Fritz Dittus and Mohammed I. Alidu for helping in the experimental setup. References ’Alvi, F. S... Thomson , M., "Minimal Controller Synthesis for Time-delay Systems Using a Smith Predictor," IEE Colloquium on Adaptive Controllers in Practice - Part Two
Plant viral vectors for delivery by Agrobacterium.
Gleba, Yuri Y; Tusé, Daniel; Giritch, Anatoli
2014-01-01
Plant viral vectors delivered by Agrobacterium are the basis of several manufacturing processes that are currently in use for producing a wide range of proteins for multiple applications, including vaccine antigens, antibodies, protein nanoparticles such as virus-like particles (VLPs), and other protein and protein-RNA scaffolds. Viral vectors delivered by agrobacterial T-DNA transfer (magnifection) have also become important tools in research. In recent years, essential advances have been made both in the development of second-generation vectors designed using the 'deconstructed virus' approach, as well as in the development of upstream manufacturing processes that are robust and fully scalable. The strategy relies on Agrobacterium as a vector to deliver DNA copies of one or more viral RNA/DNA replicons; the bacteria are delivered into leaves by vacuum infiltration, and the viral machinery takes over from the point of T-DNA transfer to the plant cell nucleus, driving massive RNA and protein production and, if required, cell-to-cell spread of the replicons. Among the most often used viral backbones are those of the RNA viruses Tobacco mosaic virus (TMV), Potato virus X (PVX) and Cowpea mosaic virus (CPMV), and the DNA geminivirus Bean yellow dwarf virus. Prototypes of industrial processes that provide for high yield, rapid scale up and fast manufacturing cycles have been designed, and several GMP-compliant and GMP-certified manufacturing facilities are in place. These efforts have been successful as evidenced by the fact that several antibodies and vaccine antigens produced by magnifection are currently in clinical development.
Byzantine Vector Consensus in Complete Graphs
2013-02-11
THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 1 Introduction This paper addresses Byzantine vector consensus...this paper is to establish the following bounds for complete graphs. • In a synchronous system, n ≥ max(3f + 1, (d+ 1)f + 1) is necessary and sufficient...Notations Many notations introduced throughout the paper are also summarized in Appendix A. We use operator | . | to obtain the size of a multiset or
The quantum vector digital voltmeter of INMETRO
NASA Astrophysics Data System (ADS)
Kuerten Ihlenfeld, Waldemar G.; Landim, Regis P.
2016-07-01
The paper describes the quantum vector digital voltmeter developed at INMETRO, which is based on a programmable Josephson voltage synthesizer. The system employs digital regulation for phase-alignment and frequency synchronization of signals, is fully automated and allows calibration of ac sources and analog-to-digital converters with uncertainties bearing some parts of 10-07 up to frequencies of around 500 Hz.
40 CFR 258.22 - Disease vector control.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 25 2014-07-01 2014-07-01 false Disease vector control. 258.22 Section... MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control. (a) Owners or operators of all MSWLF units must prevent or control on-site populations of disease vectors using...
40 CFR 258.22 - Disease vector control.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Disease vector control. 258.22 Section... MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control. (a) Owners or operators of all MSWLF units must prevent or control on-site populations of disease vectors using...
40 CFR 258.22 - Disease vector control.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 26 2013-07-01 2013-07-01 false Disease vector control. 258.22 Section... MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control. (a) Owners or operators of all MSWLF units must prevent or control on-site populations of disease vectors using...
40 CFR 258.22 - Disease vector control.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 26 2012-07-01 2011-07-01 true Disease vector control. 258.22 Section... MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control. (a) Owners or operators of all MSWLF units must prevent or control on-site populations of disease vectors using...
40 CFR 258.22 - Disease vector control.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 25 2011-07-01 2011-07-01 false Disease vector control. 258.22 Section... MUNICIPAL SOLID WASTE LANDFILLS Operating Criteria § 258.22 Disease vector control. (a) Owners or operators of all MSWLF units must prevent or control on-site populations of disease vectors using...
Scaffolding Vector Representations for Student Learning inside a Physics Game
ERIC Educational Resources Information Center
D'Angelo Cynthia
2010-01-01
Vectors and vector addition are difficult concepts for many introductory physics students and traditional instruction does not usually sufficiently address these difficulties. Vectors play a major role in most topics in introductory physics and without a complete understanding of them many students are unable to make sense of the physics topics…
Mapping the magnetic field vector in a fountain clock
Gertsvolf, Marina; Marmet, Louis
2011-12-15
We show how the mapping of the magnetic field vector components can be achieved in a fountain clock by measuring the Larmor transition frequency in atoms that are used as a spatial probe. We control two vector components of the magnetic field and apply audio frequency magnetic pulses to localize and measure the field vector through Zeeman spectroscopy.
Declining Prevalence of Disease Vectors Under Climate Change
NASA Astrophysics Data System (ADS)
Escobar, Luis E.; Romero-Alvarez, Daniel; Leon, Renato; Lepe-Lopez, Manuel A.; Craft, Meggan E.; Borbor-Cordova, Mercy J.; Svenning, Jens-Christian
2016-12-01
More than half of the world population is at risk of vector-borne diseases including dengue fever, chikungunya, zika, yellow fever, leishmaniasis, chagas disease, and malaria, with highest incidences in tropical regions. In Ecuador, vector-borne diseases are present from coastal and Amazonian regions to the Andes Mountains; however, a detailed characterization of the distribution of their vectors has never been carried out. We estimate the distribution of 14 vectors of the above vector-borne diseases under present-day and future climates. Our results consistently suggest that climate warming is likely threatening some vector species with extinction, locally or completely. These results suggest that climate change could reduce the burden of specific vector species. Other vector species are likely to shift and constrain their geographic range to the highlands in Ecuador potentially affecting novel areas and populations. These forecasts show the need for development of early prevention strategies for vector species currently absent in areas projected as suitable under future climate conditions. Informed interventions could reduce the risk of human exposure to vector species with distributional shifts, in response to current and future climate changes. Based on the mixed effects of future climate on human exposure to disease vectors, we argue that research on vector-borne diseases should be cross-scale and include climatic, demographic, and landscape factors, as well as forces facilitating disease transmission at fine scales.
Declining Prevalence of Disease Vectors Under Climate Change
Escobar, Luis E.; Romero-Alvarez, Daniel; Leon, Renato; Lepe-Lopez, Manuel A.; Craft, Meggan E.; Borbor-Cordova, Mercy J.; Svenning, Jens-Christian
2016-01-01
More than half of the world population is at risk of vector-borne diseases including dengue fever, chikungunya, zika, yellow fever, leishmaniasis, chagas disease, and malaria, with highest incidences in tropical regions. In Ecuador, vector-borne diseases are present from coastal and Amazonian regions to the Andes Mountains; however, a detailed characterization of the distribution of their vectors has never been carried out. We estimate the distribution of 14 vectors of the above vector-borne diseases under present-day and future climates. Our results consistently suggest that climate warming is likely threatening some vector species with extinction, locally or completely. These results suggest that climate change could reduce the burden of specific vector species. Other vector species are likely to shift and constrain their geographic range to the highlands in Ecuador potentially affecting novel areas and populations. These forecasts show the need for development of early prevention strategies for vector species currently absent in areas projected as suitable under future climate conditions. Informed interventions could reduce the risk of human exposure to vector species with distributional shifts, in response to current and future climate changes. Based on the mixed effects of future climate on human exposure to disease vectors, we argue that research on vector-borne diseases should be cross-scale and include climatic, demographic, and landscape factors, as well as forces facilitating disease transmission at fine scales. PMID:27982119
Declining Prevalence of Disease Vectors Under Climate Change.
Escobar, Luis E; Romero-Alvarez, Daniel; Leon, Renato; Lepe-Lopez, Manuel A; Craft, Meggan E; Borbor-Cordova, Mercy J; Svenning, Jens-Christian
2016-12-16
More than half of the world population is at risk of vector-borne diseases including dengue fever, chikungunya, zika, yellow fever, leishmaniasis, chagas disease, and malaria, with highest incidences in tropical regions. In Ecuador, vector-borne diseases are present from coastal and Amazonian regions to the Andes Mountains; however, a detailed characterization of the distribution of their vectors has never been carried out. We estimate the distribution of 14 vectors of the above vector-borne diseases under present-day and future climates. Our results consistently suggest that climate warming is likely threatening some vector species with extinction, locally or completely. These results suggest that climate change could reduce the burden of specific vector species. Other vector species are likely to shift and constrain their geographic range to the highlands in Ecuador potentially affecting novel areas and populations. These forecasts show the need for development of early prevention strategies for vector species currently absent in areas projected as suitable under future climate conditions. Informed interventions could reduce the risk of human exposure to vector species with distributional shifts, in response to current and future climate changes. Based on the mixed effects of future climate on human exposure to disease vectors, we argue that research on vector-borne diseases should be cross-scale and include climatic, demographic, and landscape factors, as well as forces facilitating disease transmission at fine scales.
Control of vectors and insecticide resistance: Implications for disease control
USDA-ARS?s Scientific Manuscript database
Effective management of insect and mite vectors of plant pathogens is of crucial importance to minimizing vector-borne diseases in crops. Insecticides play an important role in managing vector populations by reducing the number of individuals that can acquire and transmit a virus, thereby potentiall...
42 CFR 71.54 - Etiological agents, hosts, and vectors.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 1 2010-10-01 2010-10-01 false Etiological agents, hosts, and vectors. 71.54..., INSPECTION, LICENSING FOREIGN QUARANTINE Importations § 71.54 Etiological agents, hosts, and vectors. (a) A... any arthropod or other animal host or vector of human disease, or any exotic living arthropod or...
Scaffolding Vector Representations for Student Learning inside a Physics Game
ERIC Educational Resources Information Center
D'Angelo Cynthia
2010-01-01
Vectors and vector addition are difficult concepts for many introductory physics students and traditional instruction does not usually sufficiently address these difficulties. Vectors play a major role in most topics in introductory physics and without a complete understanding of them many students are unable to make sense of the physics topics…
Genetic elimination of dengue vector mosquitoes.
Wise de Valdez, Megan R; Nimmo, Derric; Betz, John; Gong, Hong-Fei; James, Anthony A; Alphey, Luke; Black, William C
2011-03-22
An approach based on mosquitoes carrying a conditional dominant lethal gene (release of insects carrying a dominant lethal, RIDL) is being developed to control the transmission of dengue viruses by vector population suppression. A transgenic strain, designated OX3604C, of the major dengue vector, Aedes aegypti, was engineered to have a repressible female-specific flightless phenotype. This strain circumvents the need for radiation-induced sterilization, allows genetic sexing resulting in male-only releases, and permits the release of eggs instead of adult mosquitoes. OX3604C males introduced weekly into large laboratory cages containing stable target mosquito populations at initial ratios of 8.5-101 OX3604Ctarget eliminated the populations within 10-20 weeks. These data support the further testing of this strain in contained or confined field trials to evaluate mating competitiveness and environmental and other effects. Successful completion of the field trials should facilitate incorporation of this approach into area-wide dengue control or elimination efforts as a component of an integrated vector management strategy.
A global map of dominant malaria vectors
2012-01-01
Background Global maps, in particular those based on vector distributions, have long been used to help visualise the global extent of malaria. Few, however, have been created with the support of a comprehensive and extensive evidence-based approach. Methods Here we describe the generation of a global map of the dominant vector species (DVS) of malaria that makes use of predicted distribution maps for individual species or species complexes. Results Our global map highlights the spatial variability in the complexity of the vector situation. In Africa, An. gambiae, An. arabiensis and An. funestus are co-dominant across much of the continent, whereas in the Asian-Pacific region there is a highly complex situation with multi-species coexistence and variable species dominance. Conclusions The competence of the mapping methodology to accurately portray DVS distributions is discussed. The comprehensive and contemporary database of species-specific spatial occurrence (currently available on request) will be made directly available via the Malaria Atlas Project (MAP) website from early 2012. PMID:22475528
Vector Beam Polarization State Spectrum Analyzer.
Moreno, Ignacio; Davis, Jeffrey A; Badham, Katherine; Sánchez-López, María M; Holland, Joseph E; Cottrell, Don M
2017-05-22
We present a proof of concept for a vector beam polarization state spectrum analyzer based on the combination of a polarization diffraction grating (PDG) and an encoded harmonic q-plate grating (QPG). As a result, a two-dimensional polarization diffraction grating is formed that generates six different q-plate channels with topological charges from -3 to +3 in the horizontal direction, and each is split in the vertical direction into the six polarization channels at the cardinal points of the corresponding higher-order Poincaré sphere. Consequently, 36 different channels are generated in parallel. This special polarization diffractive element is experimentally demonstrated using a single phase-only spatial light modulator in a reflective optical architecture. Finally, we show that this system can be used as a vector beam polarization state spectrum analyzer, where both the topological charge and the state of polarization of an input vector beam can be simultaneously determined in a single experiment. We expect that these results would be useful for applications in optical communications.
Multifractal vector fields and stochastic Clifford algebra.
Schertzer, Daniel; Tchiguirinskaia, Ioulia
2015-12-01
In the mid 1980s, the development of multifractal concepts and techniques was an important breakthrough for complex system analysis and simulation, in particular, in turbulence and hydrology. Multifractals indeed aimed to track and simulate the scaling singularities of the underlying equations instead of relying on numerical, scale truncated simulations or on simplified conceptual models. However, this development has been rather limited to deal with scalar fields, whereas most of the fields of interest are vector-valued or even manifold-valued. We show in this paper that the combination of stable Lévy processes with Clifford algebra is a good candidate to bridge up the present gap between theory and applications. We show that it indeed defines a convenient framework to generate multifractal vector fields, possibly multifractal manifold-valued fields, based on a few fundamental and complementary properties of Lévy processes and Clifford algebra. In particular, the vector structure of these algebra is much more tractable than the manifold structure of symmetry groups while the Lévy stability grants a given statistical universality.
Targeting lentiviral vectors for cancer immunotherapy
Arce, Frederick; Breckpot, Karine; Collins, Mary; Escors, David
2012-01-01
Delivery of tumour-associated antigens (TAA) in a way that induces effective, specific immunity is a challenge in anti-cancer vaccine design. Circumventing tumour-induced tolerogenic mechanisms in vivo is also critical for effective immunotherapy. Effective immune responses are induced by professional antigen presenting cells, in particular dendritic cells (DC). This requires presentation of the antigen to both CD4+ and CD8+ T cells in the context of strong co-stimulatory signals. Lentiviral vectors have been tested as vehicles, for both ex vivo and in vivo delivery of TAA and/or activation signals to DC, and have been demonstrated to induce potent T cell mediated immune responses that can control tumour growth. This review will focus on the use of lentiviral vectors for in vivo gene delivery to DC, introducing strategies to target DC, either targeting cell entry or gene expression to improve safety of the lentiviral vaccine or targeting dendritic cell activation pathways to enhance performance of the lentiviral vaccine. In conclusion, this review highlights the potential of lentiviral vectors as a generally applicable ‘off-the-shelf’ anti-cancer immunotherapeutic. PMID:22983382
Multifractal vector fields and stochastic Clifford algebra
Schertzer, Daniel Tchiguirinskaia, Ioulia
2015-12-15
In the mid 1980s, the development of multifractal concepts and techniques was an important breakthrough for complex system analysis and simulation, in particular, in turbulence and hydrology. Multifractals indeed aimed to track and simulate the scaling singularities of the underlying equations instead of relying on numerical, scale truncated simulations or on simplified conceptual models. However, this development has been rather limited to deal with scalar fields, whereas most of the fields of interest are vector-valued or even manifold-valued. We show in this paper that the combination of stable Lévy processes with Clifford algebra is a good candidate to bridge up the present gap between theory and applications. We show that it indeed defines a convenient framework to generate multifractal vector fields, possibly multifractal manifold-valued fields, based on a few fundamental and complementary properties of Lévy processes and Clifford algebra. In particular, the vector structure of these algebra is much more tractable than the manifold structure of symmetry groups while the Lévy stability grants a given statistical universality.
Innate Immune Responses to AAV Vectors.
Rogers, Geoffrey L; Martino, Ashley T; Aslanidi, George V; Jayandharan, Giridhara R; Srivastava, Arun; Herzog, Roland W
2011-01-01
Gene replacement therapy by in vivo delivery of adeno-associated virus (AAV) is attractive as a potential treatment for a variety of genetic disorders. However, while AAV has been used successfully in many models, other experiments in clinical trials and in animal models have been hampered by undesired responses from the immune system. Recent studies of AAV immunology have focused on the elimination of transgene-expressing cells by the adaptive immune system, yet the innate immune system also has a critical role, both in the initial response to the vector and in prompting a deleterious adaptive immune response. Responses to AAV vectors are primarily mediated by the TLR9-MyD88 pathway, which induces the production of pro-inflammatory cytokines by activating the NF-κB pathways and inducing type I IFN production; self-complementary AAV vectors enhance these inflammatory processes. Additionally, the alternative NF-κB pathway influences transgene expression in cells transduced by AAV. This review highlights these recent discoveries regarding innate immune responses to AAV and discusses strategies to ablate these potentially detrimental signaling pathways.
Hyperspectral image classification using Support Vector Machine
NASA Astrophysics Data System (ADS)
Moughal, T. A.
2013-06-01
Classification of land cover hyperspectral images is a very challenging task due to the unfavourable ratio between the number of spectral bands and the number of training samples. The focus in many applications is to investigate an effective classifier in terms of accuracy. The conventional multiclass classifiers have the ability to map the class of interest but the considerable efforts and large training sets are required to fully describe the classes spectrally. Support Vector Machine (SVM) is suggested in this paper to deal with the multiclass problem of hyperspectral imagery. The attraction to this method is that it locates the optimal hyper plane between the class of interest and the rest of the classes to separate them in a new high-dimensional feature space by taking into account only the training samples that lie on the edge of the class distributions known as support vectors and the use of the kernel functions made the classifier more flexible by making it robust against the outliers. A comparative study has undertaken to find an effective classifier by comparing Support Vector Machine (SVM) to the other two well known classifiers i.e. Maximum likelihood (ML) and Spectral Angle Mapper (SAM). At first, the Minimum Noise Fraction (MNF) was applied to extract the best possible features form the hyperspectral imagery and then the resulting subset of the features was applied to the classifiers. Experimental results illustrate that the integration of MNF and SVM technique significantly reduced the classification complexity and improves the classification accuracy.
NLO Vector Boson Production With Light Jets
Bern, Z.; Diana, G.; Dixon, L.J.; Febres Cordero, F.; Forde, D.; Gleisberg, T.; Hoeche, S.; Ita, H.; Kosower, D.A.; Maitre, D.; Ozeren, K.
2012-02-15
In this contribution we present recent progress in the computation of next-to-leading order (NLO) QCD corrections for the production of an electroweak vector boson in association with jets at hadron colliders. We focus on results obtained using the virtual matrix element library BlackHat in conjunction with SHERPA, focusing on results relevant to understanding the background to top production. The production of a vector boson in association with several jets at the Large Hadron Collider (LHC) is an important background for other Standard Model processes as well as new physics signals. In particular, the production of a W boson in association with many jets is an important background for processes involving one or more top quarks. Precise predictions for the backgrounds are crucial to measurement of top-quark processes. Vector boson production in association with multiple jets is also a very important background for many SUSY searches, as it mimics the signatures of many typical decay chains. Here we will discuss how polarization information can be used as an additional handle to differentiate top pair production from 'prompt' W-boson production. More generally, ratios of observables, for example for events containing a W boson versus those containing a Z boson, are expected to be better-behaved as many uncertainties cancel in such ratios. Precise calculation of ratios, along with measurement of one of the two processes in the ratio, can be used in data-driven techniques for estimating backgrounds.
Finite-state residual vector quantization
NASA Astrophysics Data System (ADS)
Rizvi, Syed A.; Wang, Lin-Cheng; Nasrabadi, Nasser M.
1995-04-01
This paper presents a new FSVQ scheme called Finite-State Residual Vector Quantization (FSRVQ) in which each state uses a Residual Vector Quantizer (RVQ) to encode the input vector. Furthermore, a novel tree- structured competitive neural network is proposed to jointly design the next-state and the state-RVQ codebooks for the proposed FSRVQ. Joint optimization of the next-state function and the state-RVQ codebooks eliminates a large number of redundant states in the conventional FSVQ design; consequently, the memory requirements are substantially reduced in the proposed FSRVQ scheme. The proposed FSRVQ can be designed for high bit rates due to its very low memory requirements and low search complexity of the state-RVQs. Simulation results show that the proposed FSRVQ scheme outperforms the conventional FSVQ schemes both in terms of memory requirements and perceptual quality of the reconstructed image. The proposed FSRVQ scheme also outperforms JPEG (current standard for still image compression) at low bit rates.
Live bacterial vaccine vectors: An overview
da Silva, Adilson José; Zangirolami, Teresa Cristina; Novo-Mansur, Maria Teresa Marques; Giordano, Roberto de Campos; Martins, Elizabeth Angélica Leme
2014-01-01
Genetically attenuated microorganisms, pathogens, and some commensal bacteria can be engineered to deliver recombinant heterologous antigens to stimulate the host immune system, while still offering good levels of safety. A key feature of these live vectors is their capacity to stimulate mucosal as well as humoral and/or cellular systemic immunity. This enables the use of different forms of vaccination to prevent pathogen colonization of mucosal tissues, the front door for many infectious agents. Furthermore, delivery of DNA vaccines and immune system stimulatory molecules, such as cytokines, can be achieved using these special carriers, whose adjuvant properties and, sometimes, invasive capacities enhance the immune response. More recently, the unique features and versatility of these vectors have also been exploited to develop anti-cancer vaccines, where tumor-associated antigens, cytokines, and DNA or RNA molecules are delivered. Different strategies and genetic tools are constantly being developed, increasing the antigenic potential of agents delivered by these systems, opening fresh perspectives for the deployment of vehicles for new purposes. Here we summarize the main characteristics of the different types of live bacterial vectors and discuss new applications of these delivery systems in the field of vaccinology. PMID:25763014