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Hanani, Abualsoud, e Rabee Naser. "Spoken Arabic dialect recognition using X-vectors". Natural Language Engineering 26, n. 6 (4 maggio 2020): 691–700. http://dx.doi.org/10.1017/s1351324920000091.
Testo completoAbstract (sommario):
AbstractThis paper describes our automatic dialect identification system for recognizing four major Arabic dialects, as well as Modern Standard Arabic. We adapted the X-vector framework, which was originally developed for speaker recognition, to the task of Arabic dialect identification (ADI). The training and development ADI VarDial 2018 and VarDial 2017 were used to train and test all of our ADI systems. In addition to the introduced X-vectors, other systems use the traditional i-vectors, bottleneck features, phonetic features, words transcriptions, and GMM-tokens. X-vectors achieved good performance (0.687) on the ADI 2018 Discriminating between Similar Languages shared task testing dataset, outperforming other systems. The performance of the X-vector system is slightly improved (0.697) when fused with i-vectors, bottleneck features, and word uni-gram features.
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Márquez, Almudena P., Francisco Javier García-Pacheco, Míriam Mengibar-Rodríguez e Alberto Sánchez-Alzola. "Supporting vectors vs. principal components". AIMS Mathematics 8, n. 1 (2023): 1937–58. http://dx.doi.org/10.3934/math.2023100.
Testo completoAbstract (sommario):
<abstract><p>Let $ T:X\to Y $ be a bounded linear operator between Banach spaces $ X, Y $. A vector $ x_0\in {\mathsf{S}}_X $ in the unit sphere $ {\mathsf{S}}_X $ of $ X $ is called a supporting vector of $ T $ provided that $ \|T(x_0)\| = \sup\{\|T(x)\|:\|x\| = 1\} = \|T\| $. Since matrices induce linear operators between finite-dimensional Hilbert spaces, we can consider their supporting vectors. In this manuscript, we unveil the relationship between the principal components of a matrix and its supporting vectors. Applications of our results to real-life problems are provided.</p></abstract>
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Mamyrbaev, O. Zh, A. S. Kydyrbekova, B. Zh Zhumazhanov e D. O. Oralbekova. "VOICE RECOGNITION USING X-VECTORS". Вестник Алматинского университета энергетики и связи, n. 1 (2021): 69–77. http://dx.doi.org/10.51775/1999-9801_2021_52_1_69.
Testo completo
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Marucci, Rosangela Cristina, Teresinha Augusta Giustolin, Marcelo Pedreira de Miranda, Helen Miquelote, Rodrigo Piacentini Paes de Almeida e João Roberto Spotti Lopes. "Identification of a non-host plant of Xylella fastidiosa to rear healthy sharpshooter vectors". Scientia Agricola 60, n. 4 (dicembre 2003): 669–75. http://dx.doi.org/10.1590/s0103-90162003000400010.
Testo completoAbstract (sommario):
Rearing leafhopper (Hemiptera: Cicadellidae) vectors free of Xylella fastidiosa is a requirement for studies of various aspects of vector-pathogen interactions. The selection of a plant that allows vector development but not bacterial multiplication is desirable to produce healthy vectors. In this study, two leafhopper hosts, Vernonia condensata ('boldo') and Aloysia virgata ('lixeira') were needle inoculated with citrus and coffee strains of X. fastidiosa to evaluate if these plants support pathogen colonization. The inoculated plants did not present symptoms and the pathogen was not detected by culture and PCR tests, neither soon after inoculation (7-14 days) nor later, at 1, 4, 6 and 12 months after inoculation. To obtain healthy adults of the leafhopper vectors Acrogonia citrina, Bucephalogonia xanthophis, Dilobopterus costalimai, Homalodisca ignorata and Oncometopia facialis, early-instar nymphs were reared on V. condensata. X. fastidiosa was not detected in any of 175 adults obtained. V. condensata and A. virgata are nonpropagative hosts of X. fastidiosa and enable the production of healthy leafhoppers for vector studies.
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Alharbi, Wedad, Daniel Freeman, Dorsa Ghoreishi, Claire Lois e Shanea Sebastian. "Stable phase retrieval and perturbations of frames". Proceedings of the American Mathematical Society, Series B 10, n. 31 (29 settembre 2023): 353–68. http://dx.doi.org/10.1090/bproc/185.
Testo completoAbstract (sommario):
A frame ( x j ) j ∈ J (x_j)_{j\in J} for a Hilbert space H H is said to do phase retrieval if for all distinct vectors x , y ∈ H x,y\in H the magnitudes of the frame coefficients ( | ⟨ x , x j ⟩ | ) j ∈ J (|\langle x, x_j\rangle |)_{j\in J} and ( | ⟨ y , x j ⟩ | ) j ∈ J (|\langle y, x_j\rangle |)_{j\in J} distinguish x x from y y (up to a unimodular scalar). A frame which does phase retrieval is said to do C C -stable phase retrieval if the recovery of any vector x ∈ H x\in H from the magnitude of the frame coefficients is C C -Lipschitz. It is known that if a frame does stable phase retrieval then any sufficiently small perturbation of the frame vectors will do stable phase retrieval, though with a slightly worse stability constant. We provide new quantitative bounds on how the stability constant for phase retrieval is affected by a small perturbation of the frame vectors. These bounds are significant in that they are independent of the dimension of the Hilbert space and the number of vectors in the frame.
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Pap, G., e Péter Major. "LIMIT THEOREMS ON THE DIRECT PRODUCT OF A NON-COMPACT LIE GROUP AND A COMPACT GROUP". Studia Scientiarum Mathematicarum Hungarica 38, n. 1-4 (1 maggio 2001): 279–97. http://dx.doi.org/10.1556/sscmath.38.2001.1-4.21.
Testo completoAbstract (sommario):
Let us consider a triangular array of random vectors (X (n) j; Y (n) j), n = 1;2;: : :, 1 5 j 5 kn, such that the first coordinates X (n) j take their values in a non-compact Lie group and the second coordinates Y (n) j in a compact group. Let the random vectors (X (n) j; Y (n) j) be independent for fixed n, but we do not assume any (independence type) condition about the relation between the components of these vectors. We show under fairly general conditions that if both random products Sn = kn Q j=1 X (n) j and Tn = kn Q j=1 Y (n) j have a limit distribution, then also the random vectors (Sn; Tn) converge in distribution as n !1 . Moreover, the non-compact and compact coordinates of a random vector with this limit distribution are independent.
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Bossi Esteves, Mariana, Julia Lopes Nalin, Karla Kudlawiec, Raquel Caserta Salviatto, Tiago de Melo Sales, Anne Sicard, Rodrigo Piacentini Paes de Almeida, Alessandra Alves de Souza e João Roberto Spotti Lopes. "XadA2 Adhesin Decreases Biofilm Formation and Transmission of Xylella fastidiosa subsp. pauca". Insects 11, n. 8 (26 luglio 2020): 473. http://dx.doi.org/10.3390/insects11080473.
Testo completoAbstract (sommario):
Xylella fastidiosa is a vector-borne bacterium that causes diseases in many plants of economic interest. The bacterium–vector initial interactions involve bacterial membrane-bound adhesins that mediate cell attachment to the foregut of insect vectors. We investigated the role of the afimbrial adhesin XadA2 in the binding and biofilm formation of X. fastidiosa subsp. pauca to vector surfaces in vitro, as well as its potential to disrupt pathogen transmission. We showed that XadA2 has binding affinity for polysaccharides on sharpshooter hindwings, used as a proxy for the interactions between X. fastidiosa and vectors. When in a medium without carbon sources, the bacterium used wing components, likely chitin, as a source of nutrients and formed a biofilm on the wing surface. There was a significant reduction in X. fastidiosa biofilm formation and cell aggregation on vector wings in competition assays with XadA2 or its specific antibody (anti-XadA2). Finally, pathogen acquisition and transmission to plant were significantly reduced when the vectors acquired X. fastidiosa from an artificial diet supplemented with anti-XadA2. These results show that XadA2 is important in mediating bacterial colonization in the insect and that it could be used as a target for blocking X. fastidiosa transmission.
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Stanke, Mario. "Sequential selection of random vectors under a sum constraint". Journal of Applied Probability 41, n. 01 (marzo 2004): 131–46. http://dx.doi.org/10.1017/s0021900200014091.
Testo completoAbstract (sommario):
We observe a sequence X 1, X 2,…, X n of independent and identically distributed coordinatewise nonnegative d-dimensional random vectors. When a vector is observed it can either be selected or rejected but once made this decision is final. In each coordinate the sum of the selected vectors must not exceed a given constant. The problem is to find a selection policy that maximizes the expected number of selected vectors. For a general absolutely continuous distribution of the X i we determine the maximal expected number of selected vectors asymptotically and give a selection policy which asymptotically achieves optimality. This problem raises a question closely related to the following problem. Given an absolutely continuous measure μ on Q = [0,1] d and a τ ∈ Q, find a set A of maximal measure μ(A) among all A ⊂ Q whose center of gravity lies below τ in all coordinates. We will show that a simplicial section { x ∈ Q | 〈 x , θ 〉 ≤ 1}, where θ ∈ ℝ d , θ ≥ 0, satisfies a certain additional property, is a solution to this problem.
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Thies, Thorsten, e Frank Weber. "Optimal Reduced-Set Vectors for Support Vector Machines with a Quadratic Kernel". Neural Computation 16, n. 9 (1 settembre 2004): 1769–77. http://dx.doi.org/10.1162/0899766041336459.
Testo completoAbstract (sommario):
To reduce computational cost, the discriminant function of a support vector machine (SVM) should be represented using as few vectors as possible. This problem has been tackled in different ways. In this article, we develop an explicit solution in the case of a general quadratic kernel k(x, x′) = (C + Dx⊺x′)2. For a given number of vectors, this solution provides the best possible approximation and can even recover the discriminant function if the number of used vectors is large enough. The key idea is to express the inhomogeneous kernel as a homogeneous kernel on a space having one dimension more than the original one and to follow the approach of Burges (1996).
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Killiny, Nabil, e Rodrigo P. P. Almeida. "Xylella fastidiosa Afimbrial Adhesins Mediate Cell Transmission to Plants by Leafhopper Vectors". Applied and Environmental Microbiology 75, n. 2 (14 novembre 2008): 521–28. http://dx.doi.org/10.1128/aem.01921-08.
Testo completoAbstract (sommario):
ABSTRACT The interactions between the economically important plant-pathogenic bacterium Xylella fastidiosa and its leafhopper vectors are poorly characterized. We used different approaches to determine how X. fastidiosa cells interact with the cuticular surface of the foreguts of vectors. We demonstrate that X. fastidiosa binds to different polysaccharides with various affinities and that these interactions are mediated by cell surface carbohydrate-binding proteins. In addition, competition assays showed that N-acetylglucosamine inhibits bacterial adhesion to vector foregut extracts and intact wings, demonstrating that attachment to leafhopper surfaces is affected in the presence of specific polysaccharides. In vitro experiments with several X. fastidiosa knockout mutants indicated that hemagglutinin-like proteins are associated with cell adhesion to polysaccharides. These results were confirmed with biological experiments in which hemagglutinin-like protein mutants were transmitted to plants by vectors at lower rates than that of the wild type. Furthermore, although these mutants were defective in adhesion to the cuticle of vectors, their growth rate once attached to leafhoppers was similar to that of the wild type, suggesting that these proteins are important for initial adhesion of X. fastidiosa to leafhoppers. We propose that X. fastidiosa colonization of leafhopper vectors is a complex, stepwise process similar to the formation of biofilms on surfaces.
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IVEZIĆ, TOMISLAV. "THE CONSTITUTIVE RELATIONS AND THE MAGNETOELECTRIC EFFECT FOR MOVING MEDIA". International Journal of Modern Physics B 26, n. 08 (30 marzo 2012): 1250040. http://dx.doi.org/10.1142/s0217979212500403.
Testo completoAbstract (sommario):
In this paper the constitutive relations for moving media with homogeneous and isotropic electric and magnetic properties are presented as the connections between the generalized magnetization–polarization bivector [Formula: see text] and the electromagnetic field F. Using the decompositions of F and [Formula: see text], it is shown how the polarization vector P(x) and the magnetization vector M(x) depend on E, B and two different velocity vectors, u — the bulk velocity vector of the medium, and v — the velocity vector of the observers who measure E and B fields. These constitutive relations with four-dimensional geometric quantities, which correctly transform under the Lorentz transformations (LT), are compared with Minkowski's constitutive relations with the 3-vectors and several essential differences are pointed out. They are caused by the fact that, contrary to the general opinion, the usual transformations of the 3-vectors E, B, P, M, etc. are not the LT. The physical explanation is presented for the existence of the magnetoelectric effect in moving media that essentially differs from the traditional one.
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Abdurrahman, Ahmad Iqbal, e Amalia Zahra. "Spoken language identification using i-vectors, x-vectors, PLDA and logistic regression". Bulletin of Electrical Engineering and Informatics 10, n. 4 (1 agosto 2021): 2237–44. http://dx.doi.org/10.11591/eei.v10i4.2893.
Testo completoAbstract (sommario):
In this paper, i-vector and x-vector is used to extract the features from speech signal from local Indonesia languages, namely Javanese, Sundanese and Minang languages to help classifier identify the language spoken by the speaker. Probabilistic linear discriminant analysis (PLDA) are used as the baseline classifier and logistic regression technique are used because of prior studies showing logistic regression has better performance than PLDA for classifying speech data. Once these features are extracted. The feature is going to be classified using the classifier mentioned before. In the experiment, we tried to segment the test data to three segment such as 3, 10, and 30 seconds. This study is expanded by testing multiple parameters on the i-vector and x-vector method then comparing PLDA and logistic regression performance as its classifier. The x-vector has better score than i-vector for every segmented data while using PLDA as its classifier, except where the i-vector and x-vector is using logistic regression, i-vector still has better accuracy compared to x-vector.
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Köppl, Dominik. "Dynamic Skyline Computation with LSD Trees". Analytics 2, n. 1 (9 febbraio 2023): 146–62. http://dx.doi.org/10.3390/analytics2010009.
Testo completoAbstract (sommario):
Given a set of high-dimensional feature vectors S⊂Rn, the skyline or Pareto problem is to report the subset of vectors in S that are not dominated by any vector of S. Vectors closer to the origin are preferred: we say a vector x is dominated by another distinct vector y if x is equally or further away from the origin than y with respect to all its dimensions. The dynamic skyline problem allows us to shift the origin, which changes the answer set. This problem is crucial for dynamic recommender systems where users can shift the parameters and thus shift the origin. For each origin shift, a recomputation of the answer set from scratch is time intensive. To tackle this problem, we propose a parallel algorithm for dynamic skyline computation that uses multiple local split decision (LSD) trees concurrently. The geometric nature of the LSD trees allows us to reuse previous results. Experiments show that our proposed algorithm works well if the dimension is small in relation to the number of tuples to process.
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Chen, Angel Y. S., Jaclyn S. Zhou, Jin-Xiang Liu e James C. K. Ng. "Nuances of Whitefly Vector–Crinivirus Interactions Revealed in the Foregut Retention and Transmission of Lettuce Chlorosis Virus by Two Bemisia tabaci Cryptic Species". Viruses 13, n. 8 (10 agosto 2021): 1578. http://dx.doi.org/10.3390/v13081578.
Testo completoAbstract (sommario):
Lettuce infectious yellows virus is the first crinivirus for which the retention of purified virions ingested into the whitefly (Bemisia tabaci New World (NW)) vector’s foregut, has been demonstrated to be a requisite for successful virus transmission. This key finding supports the hypothesis that the determinant of foregut retention and transmission is present on the virion itself. However, whether this is also true for other criniviruses has not been established. Here, we provide evidence that lettuce chlorosis virus (LCV) acquired from plants is retained in the foreguts of both the B. tabaci NW and Middle East–Asia Minor 1 (MEAM1) vector species and transmitted upon inoculation feeding. An association between foregut retention and transmission by NW vectors is also observed following the acquisition and inoculation feeding of LCV virions purified using a standard procedure involving 2% or 4% (v/v) Triton™ X-100 (TX-100). However, while virions purified with 2% or 4% TX-100 are also retained in the foreguts of MEAM1 vectors, transmission is observed with the 4% TX-100-purified virions or when more vectors are used for acquisition and inoculation feeding. These results suggest that an intrinsic difference exists between NW and MEAM1 vectors in their interactions with, and transmission of, LCV virions.
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Cornara, D., A. Sicard, A. R. Zeilinger, F. Porcelli, A. H. Purcell e R. P. P. Almeida. "Transmission of Xylella fastidiosa to Grapevine by the Meadow Spittlebug". Phytopathology® 106, n. 11 (novembre 2016): 1285–90. http://dx.doi.org/10.1094/phyto-05-16-0202-r.
Testo completoAbstract (sommario):
There is little information available on Xylella fastidiosa transmission by spittlebugs (Hemiptera, Cercopoidea). This group of insect vectors may be of epidemiological relevance in certain diseases, so it is important to better understand the basic parameters of X. fastidiosa transmission by spittlebugs. We used grapevines as a host plant and the aphrophorid Philaenus spumarius as a vector to estimate the effect of plant access time on X. fastidiosa transmission to plants; in addition, bacterial population estimates in the heads of vectors were determined and correlated with plant infection status. Results show that transmission efficiency of X. fastidiosa by P. spumarius increased with plant access time, similarly to insect vectors in another family (Hemiptera, Cicadellidae). Furthermore, a positive correlation between pathogen populations in P. spumarius and transmission to plants was observed. Bacterial populations in insects were one to two orders of magnitude lower than those observed in leafhopper vectors, and population size peaked within 3 days of plant access period. These results suggest that P. spumarius has either a limited number of sites in the foregut that may be colonized, or that fluid dynamics in the mouthparts of these insects is different from that in leafhoppers. Altogether our results indicate that X. fastidiosa transmission by spittlebugs is similar to that by leafhoppers. In addition, the relationship between cell numbers in vectors and plant infection may have under-appreciated consequences to pathogen spread.
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Labroussaa, Fabien, Adam R. Zeilinger e Rodrigo P. P. Almeida. "Blocking the Transmission of a Noncirculative Vector-Borne Plant Pathogenic Bacterium". Molecular Plant-Microbe Interactions® 29, n. 7 (luglio 2016): 535–44. http://dx.doi.org/10.1094/mpmi-02-16-0032-r.
Testo completoAbstract (sommario):
The successful control of insect-borne plant pathogens is often difficult to achieve due to the ecologically complex interactions among pathogens, vectors, and host plants. Disease management often relies on pesticides and other approaches that have limited long-term sustainability. To add a new tool to control vector-borne diseases, we attempted to block the transmission of a bacterial insect-transmitted pathogen, the bacterium Xylella fastidiosa, by disrupting bacteria–insect vector interactions. X. fastidiosa is known to attach to and colonize the cuticular surface of the mouthparts of vectors; a set of recombinant peptides was generated and the chemical affinities of these peptides to chitin and related carbohydrates was assayed in vitro. Two candidates, the X. fastidiosa hypothetical protein PD1764 and an N-terminal region of the hemagglutinin-like protein B (HxfB) showed affinity for these substrates. These proteins were provided to vectors via an artificial diet system in which insects acquire X. fastidiosa, followed by an inoculation access period on plants under greenhouse conditions. Both PD1764 and HxfAD1-3 significantly blocked transmission. Furthermore, bacterial populations within insects over a 10-day period demonstrated that these peptides inhibited cell adhesion to vectors but not bacterial multiplication, indicating that the mode of action of these peptides is restricted to limiting cell adhesion to insects, likely via competition for adhesion sites. These results open a new venue in the search for sustainable disease-control strategies that are pathogen specific and may have limited nontarget effects.
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Luan, Tianjiao, Zhichao Wang, Yang Long, Zhen Zhang, Qi Li, Zhihao Zhu e Chunhua Liu. "Multi-Virtual-Vector Model Predictive Current Control for Dual Three-Phase PMSM". Energies 14, n. 21 (3 novembre 2021): 7292. http://dx.doi.org/10.3390/en14217292.
Testo completoAbstract (sommario):
This paper proposes a multi-virtual-vector model predictive control (MPC) for a dual three-phase permanent magnet synchronous machine (DTP-PMSM), which aims to regulate the currents in both fundamental and harmonic subspace. Apart from the fundamental α-β subspace, the harmonic subspace termed x-y is decoupled in multiphase PMSM according to vector space decomposition (VSD). Hence, the regulation of x-y currents is of paramount importance to improve control performance. In order to take into account both fundamental and harmonic subspaces, this paper presents a multi-virtual-vector model predictive control (MVV-MPC) scheme to significantly improve the steady performance without affecting the dynamic response. In this way, virtual vectors are pre-synthesized to eliminate the components in the x-y subspace and then a vector with adjustable phase and amplitude is composed of two effective virtual vectors and a zero vector. As a result, an enhanced current tracking ability is acquired due to the expanded output range of the voltage vector. Lastly, both simulation and experimental results are given to confirm the feasibility of the proposed MVV-MPC for DTP-PMSM.
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Hendrie, Paul C., Roli K. Hirata e David W. Russell. "Chromosomal Integration and Homologous Gene Targetingby Replication-Incompetent Vectors Based on the Autonomous ParvovirusMinute Virus ofMice". Journal of Virology 77, n. 24 (15 dicembre 2003): 13136–45. http://dx.doi.org/10.1128/jvi.77.24.13136-13145.2003.
Testo completoAbstract (sommario):
ABSTRACT The molecular mechanisms responsible for random integration and gene targeting by recombinant adeno-associated virus (AAV) vectors are largely unknown, and whether vectors derived from autonomous parvoviruses transduce cells by similar pathways has not been investigated. In this report, we constructed vectors based on the autonomous parvovirus minute virus of mice (MVM) that were designed to introduce a neomycin resistance expression cassette (neo) into the X-linked human hypoxanthine phosphoribosyl transferase (HPRT) locus. High-titer, replication-incompetent MVM vector stocks were generated with a two-plasmid transfection system that preserved the wild-type characteristic of packaging only one DNA strand. Vectors with inserts in the forward or reverse orientations packaged noncoding or coding strands, respectively. In human HT-1080 cells, MVM vector random integration frequencies (neo+ colonies) were comparable to those obtained with AAV vectors, and no difference was observed for noncoding and coding strands. HPRT gene-targeting frequencies (HPRT mutant colonies) were lower with MVM vectors, and the noncoding strand frequency was threefold greater than that of the coding strand. Random integration and gene-targeting events were confirmed by Southern blot analysis of G418- and 6-thioguanine (6TG)-resistant clones. In separate experiments, correction of an alkaline phosphatase (AP) gene by gene targeting was nine times more effective with a coding strand vector. The data suggest that single-stranded parvoviral vector genomes are substrates for gene targeting and possibly for random integration as well.
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Shikata, Shinichi, e Naoya Akashi. "Dislocation Vector Analysis Method of Deep Dislocation Having C-Axis Segment in Diamond". Materials Science Forum 1004 (luglio 2020): 519–24. http://dx.doi.org/10.4028/www.scientific.net/msf.1004.519.
Testo completoAbstract (sommario):
X-ray topography is an effective tool to investigate dislocations in semiconductor crystals. Due to low X-ray absorption coefficients of diamond, X-rays can penetrate deep into the crystal. Thus, deep three-dimensional (3D) dislocations are projected on two-dimension (2D) film, which makes dislocation analysis particularly challenging. Dislocation vectors from the films obtained using a set of the same diffraction vectors were identified using topographical and geometrical analyses. The depth and position of the dislocations in a crystal that was projected on a film were determined using geometrical relationship. The proposed analysis method was verified by analyzing several dislocations using four <404> diffraction films. The types of dislocation were identified through Burgers vector analysis.
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DuBridge, R. B., P. Tang, H. C. Hsia, P. M. Leong, J. H. Miller e M. P. Calos. "Analysis of mutation in human cells by using an Epstein-Barr virus shuttle system". Molecular and Cellular Biology 7, n. 1 (gennaio 1987): 379–87. http://dx.doi.org/10.1128/mcb.7.1.379-387.1987.
Testo completoAbstract (sommario):
We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus (EBV). EBV vectors carrying the bacterial lacI gene as the target for mutation were established in human cells and later returned to Escherichia coli for rapid detection and analysis of lacI mutations. The majority of the clonal cell lines created by establishment of the lacI-EBV vector show spontaneous LacI- frequencies of less than 10(-5) and are suitable for studies of induced mutation. The ability to isolate clonal lines represents a major advantage of the EBV vectors over transiently replicating shuttle vectors (such as those derived from simian virus 40) for the study of mutation. The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea. A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions. These data provide support for the mutational theory of cancer.
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DuBridge, R. B., P. Tang, H. C. Hsia, P. M. Leong, J. H. Miller e M. P. Calos. "Analysis of mutation in human cells by using an Epstein-Barr virus shuttle system." Molecular and Cellular Biology 7, n. 1 (gennaio 1987): 379–87. http://dx.doi.org/10.1128/mcb.7.1.379.
Testo completoAbstract (sommario):
We developed highly sensitive shuttle vector systems for detection of mutations formed in human cells using autonomously replicating derivatives of Epstein-Barr virus (EBV). EBV vectors carrying the bacterial lacI gene as the target for mutation were established in human cells and later returned to Escherichia coli for rapid detection and analysis of lacI mutations. The majority of the clonal cell lines created by establishment of the lacI-EBV vector show spontaneous LacI- frequencies of less than 10(-5) and are suitable for studies of induced mutation. The ability to isolate clonal lines represents a major advantage of the EBV vectors over transiently replicating shuttle vectors (such as those derived from simian virus 40) for the study of mutation. The DNA sequence changes were determined for 61 lacI mutations induced by exposure of one of the cell lines to N-nitroso-N-methylurea. A total of 33 of 34 lacI nonsense mutations and 26 of 27 missense mutations involve G X C to A X T transitions. These data provide support for the mutational theory of cancer.
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Hendrie, Paul C., e David W. Russell. "A Rapid Method for Comparing the Oncogenic Potential of Retroviral Vectors." Blood 106, n. 11 (16 novembre 2005): 1282. http://dx.doi.org/10.1182/blood.v106.11.1282.1282.
Testo completoAbstract (sommario):
Abstract Retroviral gene transfer has successfully cured patients with X-linked severe combined immunodeficiency (X-SCID). Unfortunately, three of the treated patients developed leukemia at least in part due to insertional activation of a neighboring gene. Further advances of this exciting therapeutic modality will require safer viral vectors. Genotoxicity experiments in animals, although an important preclinical study, are not practical for screening large numbers of vectors. We have developed a rapid plasmid-based assay to compare downstream gene activation by retroviral vectors. We constructed a plasmid, pACT, that contains a minimal CMV promoter, an internal ribosome entry site (IRES) and a luciferase reported gene followed by a polyadenylation site. Four different proviral constructs containing identical internal PGK-EGFP expression cassettes were inserted upstream of the minimal promoter and nucleofected (Amaxa Biosystems) into K562 cells. The relative luciferase activation of each provirus was determined and compared to cells nucleofected with the basic pACT plasmid. The relative luciferase activation by a plasmid containing a Moloney murine leukemia virus (MLV) vector provirus with full length long terminal repeats (LTRs) was 144, 1230, and 4525 at 1, 2 and 4 days post nucleofection, respectively. Changing the orientation of the proviral DNA did not significantly change the results, consistent with an enhancer effect from the proviral LTRs. In comparison, the relative luciferase activation by a plasmid containing a self inactivating (SIN) MLV vector provirus with LTR deletions was only 59, 90 and 170, respectively, and was reduced by greater than 90% with the reverse orientation consistent with residual activation by read-through transcription. For plasmids containing the HIV SIN vector provirus, the relative luciferase activation was 48, 45 and 52, respectively at 1, 2 and 4 days post nucleofection, and decreased by >90% with the inverse orientation. The relative luciferase activation for plasmids containing the Foamy Virus (FV) vector provirus, also a “SIN” vector, was the least, only 3, 2 and 6, respectively, at 1, 2 and 4 days post nucleofection. Therefore, all three SIN vectors (MLV, HIV and FV) produced significantly less downstream gene activation than a conventional MLV vector, with the FV vectors being the lowest. Additional studies comparing various internal promoters and vectors will also be presented. These results demonstrate the usefulness of the pACT assay system to identify safer retroviral vectors.
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Chen, R., e A. C. Ward. "The SUFFICIENT-POINTS family of propagation operations for intervals on simultaneous linear equations". Artificial Intelligence for Engineering Design, Analysis and Manufacturing 9, n. 3 (giugno 1995): 211–17. http://dx.doi.org/10.1017/s0890060400002444.
Testo completoAbstract (sommario):
AbstractThis paper defines, develops algorithms for, and illustrates the design use of a class of mathematical operations. These operations accept as inputs a system of linear constraint equations, Ax = b, an interval matrix of values for the coefficients A, and an interval vector of values for either x or b. They return a set of values for the other variable that is “sufficient” in this sense. Suppose that ◯ is an interval of input vectors, and  an interval matrix. Then, one Sufficient-Points operation returns a set of vectors ~ such that for each b in ~, the set of x values that can be produced by inserting all the values of  into Ax = b is a superset of the input vector x. These operations have been partly overlooked by the interval matrix mathematics community, but are mathematically interesting and useful in the design, for example, of circuits.
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BROUWER, ROELOF K. "A PROPOSED MAX-PRODUCT THRESHOLD UNIT FOR CLASSIFICATION OF PATTERN VECTORS". International Journal of Neural Systems 11, n. 03 (giugno 2001): 271–79. http://dx.doi.org/10.1142/s0129065701000710.
Testo completoAbstract (sommario):
This paper proposes a max-product threshold unit (maptu) that can successfully perform dichotomous classifications of pattern vectors. Maptu, with weight vector, w, classifies a pattern vector, x, by comparing x max-prod w to 0.5. Results obtained by other methods in classification of benchmark data are used for comparison to the method using maptu. The benchmark data consists of the Australian credit data set, cervical cell data set, diabetes data set and the iris data set.
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Burbank, Lindsey P., e Drake C. Stenger. "Plasmid Vectors for Xylella fastidiosa Utilizing a Toxin-Antitoxin System for Stability in the Absence of Antibiotic Selection". Phytopathology® 106, n. 8 (agosto 2016): 928–36. http://dx.doi.org/10.1094/phyto-02-16-0097-r.
Testo completoAbstract (sommario):
The phytopathogen Xylella fastidiosa causes disease in a variety of important crop and landscape plants. Functional genetic studies have led to a broader understanding of virulence mechanisms used by this pathogen in the grapevine host. Plasmid shuttle vectors are important tools in studies of bacterial genetics but there are only a limited number of plasmid vectors available that replicate in X. fastidiosa, and even fewer that are retained without antibiotic selection. Two plasmids are described here that show stable replication in X. fastidiosa and are effective for gene complementation both in vitro and in planta. Plasmid maintenance is facilitated by incorporation of the PemI/PemK plasmid addiction system, consisting of PemK, an endoribonuclease toxin, and its cognate antitoxin, PemI. Vector pXf20pemIK utilizes a native X. fastidiosa replication origin as well as a high-copy-number pUC origin for propagation in Escherichia coli cloning strains. Broad-host-range vector pBBR5pemIK is a medium- to low-copy-number plasmid based on the pBBR1 backbone. Both plasmids are maintained for extended periods of time in the absence of antibiotic selection, as well as up to 14 weeks in grapevine, without affecting bacterial fitness. These plasmids present an alternative to traditional complementation and expression vectors which rely on antibiotic selection for plasmid retention.
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Misbullah, Alim, Muhammad Saifullah Sani, Husaini, Laina Farsiah, Zahnur e Kikye Martiwi Sukiakhy. "Sistem Identifikasi Pembicara Berbahasa Indonesia Menggunakan X-Vector Embedding". Jurnal Teknologi Informasi dan Ilmu Komputer 11, n. 2 (25 aprile 2024): 369–76. http://dx.doi.org/10.25126/jtiik.20241127866.
Testo completoAbstract (sommario):
Penyemat pembicara adalah vektor yang terbukti efektif dalam merepresentasikan karakteristik pembicara sehingga menghasilkan akurasi yang tinggi dalam ranah pengenalan pembicara. Penelitian ini berfokus pada penerapan x-vectors sebagai penyemat pembicara pada sistem identifikasi pembicara berbahasa Indonesia yang menggunakan model speaker identification. Model dibangun dengan menggunakan dataset VoxCeleb sebagai data latih dan dataset INF19 sebagai data uji yang dikumpulkan dari suara mahasiswa Jurusan Informatika Universitas Syiah Kuala angkatan 2019. Untuk membangun model, fitur-fitur diekstrak dengan menggunakan Mel-Frequency Cepstral Coeffients (MFCC), dihitung Voice Activity Detection (VAD), dilakukan augmentasi dan normalisasi fitur menggunakan Cepstral Mean and Variance Normalization (CMVN) serta dilakukan filtering. Sedangkan proses pengujian model hanya membutuhkan fitur-fitur yang diekstrak dengan menggunakan MFCC dan dihitung VAD saja. Terdapat 4 (empat) model yang dibangun dengan cara mengombinasikan dua jenis konfigurasi MFCC dan dua jenis arsitektur Deep Neural Network (DNN) yang memanfaatkan Time Delay Neural Network (TDNN). Model terbaik dipilih berdasarkan akurasi tertinggi yang dihitung menggunakan metrik Equal Error Rate (EER) dan durasi ekstraksi x-vectors tersingkat dari keempat model. Nilai EER dari model yang terbaik untuk dataset VoxCeleb1 bagian test sebesar 3,51%, inf19_test_td sebesar 1,3%, dan inf19_test_tid sebesar 1,4%. Durasi ekstraksi x-vectors menggunakan model terbaik untuk data train berdurasi 6 jam 42 menit 39 detik, VoxCeleb1 bagian test berdurasi 2 menit 24 detik, inf19_enroll berdurasi 18 detik, inf19_test_td berdurasi 25 detik, dan inf19_test_tid berdurasi 9 detik. Arsitektur DNN kedua dan konfigurasi MFCC kedua yang telah dirancang menghasilkan model yang lebih kecil, akurasi yang lebih baik terutama untuk dataset pembicara berbahasa Indonesia, dan durasi ekstraksi x-vectors yang lebih singkat. Abstract The speaker embedding is a vector that has been proven effective in representing speaker characteristics, resulting in high accuracy in the domain of speaker recognition. This research focuses on the application of x-vectors as speaker embeddings in the Indonesian language speaker identification system using a speaker identification model. The model is built using the VoxCeleb dataset as training data and the INF19 dataset as testing data, collected from the voices of students of Informatics Department, Universitas Syiah Kuala from the 2019 batch. To build the model, features are extracted using Mel-Frequency Cepstral Coefficients (MFCC), Voice Activity Detection (VAD) is applied, augmentation and normalization of features are performed using Cepstral Mean and Variance Normalization (CMVN), and filtering is applied. On the other hand, the model testing process only requires features extracted using MFCC and computed VAD. There are 4 (four) models are constructed by combining two configurations of MFCC and two types of Deep Neural Network (DNN) architectures that utilize the Time Delay Neural Network (TDNN). The best model is selected based on the highest accuracy calculated using the Equal Error Rate (EER) metric and the shortest duration of x-vector extraction from the four models. The EER values for the best model on the VoxCeleb1 test dataset are 3.51%, 1.3% for inf19_test_td, and 1.4% for inf19_test_tid. The x-vector extraction duration using the best model for the training dataset is 6 hours 42 minutes 39 seconds, 2 minutes 24 seconds for VoxCeleb1 test part, 18 seconds for inf19_enroll, 25 seconds for inf19_test_td, and 9 seconds for inf19_test_tid. The second DNN architecture and the second MFCC configuration designed result in a smaller model, better accuracy, especially for Indonesian language speaker datasets, and shorter x-vector extraction duration.
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Stanke, Mario. "Sequential selection of random vectors under a sum constraint". Journal of Applied Probability 41, n. 1 (marzo 2004): 131–46. http://dx.doi.org/10.1239/jap/1077134673.
Testo completoAbstract (sommario):
We observe a sequence X1, X2,…, Xn of independent and identically distributed coordinatewise nonnegative d-dimensional random vectors. When a vector is observed it can either be selected or rejected but once made this decision is final. In each coordinate the sum of the selected vectors must not exceed a given constant. The problem is to find a selection policy that maximizes the expected number of selected vectors. For a general absolutely continuous distribution of the Xi we determine the maximal expected number of selected vectors asymptotically and give a selection policy which asymptotically achieves optimality. This problem raises a question closely related to the following problem. Given an absolutely continuous measure μ on Q = [0,1]d and a τ ∈ Q, find a set A of maximal measure μ(A) among all A ⊂ Q whose center of gravity lies below τ in all coordinates. We will show that a simplicial section {x ∈ Q | 〈x, θ〉 ≤ 1}, where θ ∈ ℝd, θ ≥ 0, satisfies a certain additional property, is a solution to this problem.
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Zhou, Sheng, Disha Mody, Suk See DeRavin, Julia Hauer, Taihe Lu, Zhijun Ma, Salima Hacein-Bey Abina et al. "A self-inactivating lentiviral vector for SCID-X1 gene therapy that does not activate LMO2 expression in human T cells". Blood 116, n. 6 (12 agosto 2010): 900–908. http://dx.doi.org/10.1182/blood-2009-10-250209.
Testo completoAbstract (sommario):
Abstract To develop safer and more effective vectors for gene therapy of X-linked severe combined immunodeficiency (SCID-X1), we have evaluated new self-inactivating lentiviral vectors based on the HIV virus. The CL20i4-hγc-Revgen vector contains the entire human common γ chain (γc) genomic sequence driven by the γc promoter. The CL20i4-EF1α-hγcOPT vector uses a promoter fragment from the eukaryotic elongation factor alpha (EF1α) gene to express a codon-optimized human γc cDNA. Both vectors contain a 400-bp insulator fragment from the chicken β-globin locus within the self-inactivating long-terminal repeat. Transduction of bone marrow cells using either of these vectors restored T, B, and natural killer lymphocyte development and function in a mouse SCID-X1 transplantation model. Transduction of human CD34+ bone marrow cells from SCID-X1 patients with either vector restored T-cell development in an in vitro assay. In safety studies using a Jurkat LMO2 activation assay, only the CL20i4-EF1α-hγcOPT vector lacked the ability to transactivate LMO2 protein expression, whereas the CL20i4-hγc-Revgen vector significantly activated LMO2 protein expression. In addition, the CL20i4-EF1α-hγcOPT vector has not caused any tumors in transplanted mice. We conclude that the CL20i4-EF1α-hγcOPT vector may be suitable for testing in a clinical trial based on these preclinical demonstrations of efficacy and safety.
29
Retter, M., P. Kienzler e P. F. Germann. "Vectors of subsurface stormflow in a layered hillslope during runoff initiation". Hydrology and Earth System Sciences Discussions 2, n. 6 (30 novembre 2005): 2521–47. http://dx.doi.org/10.5194/hessd-2-2521-2005.
Testo completoAbstract (sommario):
Abstract. The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m2 trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil) to 40 cm (close to bedrock interface). The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis) dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis) varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The results of the vector approach are compared with hydrometric measurements such as subsurface stromflow, collected at the downhill end of the slope.
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Tunçer, Yılmaz. "A Different View on Dynamics of Space Curves Geometry". Journal of Nonlinear Mathematical Physics 29, n. 1 (16 dicembre 2021): 73–94. http://dx.doi.org/10.1007/s44198-021-00023-8.
Testo completoAbstract (sommario):
AbstractIn this study, we define the X-torque curves, $$X-$$ X - equilibrium curves, X-moment conservative curves, $$X-$$ X - gyroscopic curves as new curves derived from a regular space curve by using the Frenet vectors of a space curve and its position vector, where $$X\in \left\{ T\left( s\right) , N\left( s\right) , B\left( s\right) \right\} $$ X ∈ T s , N s , B s and we examine these curves and we give their properties.
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Chelnokov, Yu N., e A. V. Molodenkov. "Quaternion Algorithm for Initial Alignment of Strapdown INS Using the A. N. Tikhonov Regularization Method". Mekhatronika, Avtomatizatsiya, Upravlenie 22, n. 4 (5 aprile 2021): 217–24. http://dx.doi.org/10.17587/mau.22.217-224.
Testo completoAbstract (sommario):
For the functioning of algorithms of inertial orientation and navigation of strapdown inertial navigation system (SINS), it is necessary to conduct a mathematical initial alignment of SINS immediately before the operation of these algorithms. An efficient method of initial alignment (not calibration!) of SINS is the method of vector matching. Its essence is to determine the relative orientation of the instrument trihedron Y (related to the unit of SINS sensors) and the reference trihedron X according to the results of measuring the projections of at least two non-collinear vectors of the axes on both trihedrons. We address the estimation of the initial orientation of the object using the method of gyrocompassing, which is a form of vector matching method. This initial alignment method is based upon using the projections of the apparent acceleration vector a and the absolute angular velocity vector ω of the object in the coordinate systems X and Y. It is assumed that the three single-axis accelerometers and the three gyroscopes (generally speaking, the three absolute angular velocity sensors of any type), which measure the projections of the vectors a and ω, are installed along the axes of the instrument coordinate system Y. If the projections of the same vectors on the axes of the base coordinate system X are known, then it is possible to estimate the mutual orientation of X and Y trihedrons. We are solving the problem of the initial alignment of SINS for the case of a fixed base, when the accelerometers measure the projection gi (i = 1, 2, 3) of the gravity acceleration vector g, and the gyroscopes measure the projections u i of the vector u of angular velocity of Earth’s rotation on the body-fixed axes. The projections of the same vectors on the axes of the normal geographic coordinate system X are also estimated using the known formulas. The correlation between the projections of the vectors u and g in X and Y coordinate system is given by known quaternion relations. In these relations the unknown variable is the orientation quaternion of the object in the X coordinate system. By separating the scalar and vector parts in the equations, we obtain an overdetermined system of linear algebraic equations (SLAE), where the unknown variable is the finite rotation vector θ, which aligns the X and Y coordinate systems (it is assumed that there is no half-turn of the X coordinate system with respect to the Y coordinate system). Thus, the mathematical formulation of the problem of SINS initial alignment by means of gyrocompassing is to find the unknown vector θ from the derived overdetermined SLAE. When finding the vector θ directly from the SLAE (algorithm 1) and data containing measurement errors, the components of the vector q are also determined with errors (especially the component of the vector θ, which is responsible for the course ψ of an object). Depending on the pre-defined in the course of numerical experiments values of heading ψ, roll ϑ, pitch γ angles of an object and errors of the input data (measurements of gyroscopes and accelerometers), the errors of estimating the heading angle Δψ of an object may in many cases differ from the errors of estimating the roll Δϑ and pitch Δγ angles by two-three (typically) or more orders. Therefore, in order to smooth out these effects, we have used the A. N. Tikhonov regularization method (algorithm 2), which consists of multiplying the left and right sides of the SLAE by the transposed matrix of coefficients for that SLAE, and adding the system regularization parameter to the elements of the main diagonal of the coefficient matrix for the newly derived SLAE (if necessary, depending on the value of the determinant of this matrix). Analysis of the results of the numerical experiments on the initial alignment shows that the errors of estimating the object’s orientation angles Δψ, Δϑ, Δγ using algorithm 2 are more comparable (more consistent) regarding their order.
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Merhav, Neri. "A Universal Random Coding Ensemble for Sample-Wise Lossy Compression". Entropy 25, n. 8 (11 agosto 2023): 1199. http://dx.doi.org/10.3390/e25081199.
Testo completoAbstract (sommario):
We propose a universal ensemble for the random selection of rate–distortion codes which is asymptotically optimal in a sample-wise sense. According to this ensemble, each reproduction vector, x^, is selected independently at random under the probability distribution that is proportional to 2−LZ(x^), where LZ(x^) is the code length of x^ pertaining to the 1978 version of the Lempel–Ziv (LZ) algorithm. We show that, with high probability, the resulting codebook gives rise to an asymptotically optimal variable-rate lossy compression scheme under an arbitrary distortion measure, in the sense that a matching converse theorem also holds. According to the converse theorem, even if the decoder knew the ℓ-th order type of source vector in advance (ℓ being a large but fixed positive integer), the performance of the above-mentioned code could not have been improved essentially for the vast majority of codewords pertaining to source vectors in the same type. Finally, we present a discussion of our results, which includes among other things, a clear indication that our coding scheme outperforms the one that selects the reproduction vector with the shortest LZ code length among all vectors that are within the allowed distortion from the source vector.
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Yuan, Qingqing, Renji Zhao, Rongyan Xiao e Zhiyong Liu. "Zero Common-Mode Voltage Model Predictive Torque Control Based on Virtual Voltage Vectors for the Dual Three-Phase PMSM Drive". Electronics 11, n. 20 (13 ottobre 2022): 3293. http://dx.doi.org/10.3390/electronics11203293.
Testo completoAbstract (sommario):
For the multiphase motor drive system, current harmonic components in stator windings and the common-mode voltage are the main factors affecting the control performance. In this paper, a novel model predictive torque control (MPTC) considering both harmonic and common-mode voltage suppression is proposed to improve the control performance. First, with the vector space decoupling (VSD) theory, 12 virtual voltage vectors are constructed based on the principle that the amplitudes of the vectors in the x-y harmonic subplace are zero to achieve the harmonic suppression. Then, these 12 virtual vectors are further simplified to six vectors to realize the common-mode voltage suppression, and they are taken as the candidate vectors to be rolling optimized to output the optimal voltage vector. This novel MPTC strategy can reduce the computational burden and avoid the weight factor design for the traditional multi-objective optimization. The effectiveness of this novel MPTC strategy was verified by simulations and experiments in comparison with normal MPTC methods, and it can save over 44% of the execution time of the traditional MPTC method and provide better suppression of the harmonic current components and the common-mode voltage.
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GARGANI, ELISABETTA, CLAUDIA BENVENUTI, LEONARDO MARIANELLI, PIO FEDERICO ROVERSI, MASSIMO RICCIOLINI, ILARIA SCARPELLI, PATRIZIA SACCHETTI et al. "A FIVE-YEAR SURVEY IN TUSCANY (ITALY) AND DETECTION OF XYLELLA FASTIDIOSASUBSPECIES MULTIPLEXIN POTENTIAL INSECT VECTORS, COLLECTED IN MONTE ARGENTARIO". Redia 104 (12 maggio 2021): 75–88. http://dx.doi.org/10.19263/redia-104.21.09.
Testo completoAbstract (sommario):
The vector‐borne bacterium Xylella fastidiosa(Wells and Raju) causes several serious diseases to plants. Recently, different subspecies of X. fastidiosa were reported in some European countries. The risk of the bacterium’s spread on the entire European territory is very high; therefore, it has been added into the priority pest list (2019/1702/EU Regulation). The main purposes of this work were to verify the presence of potential vectors in areas at a high risk of introduction in Tuscany and to ascertain the presence of X. fastidiosa in these insect vectors. Over 4,000 Auchenorrhyncha were collected and analysed from 2015 to 2019. Among the xylem sap-feeder putative vectors, most of the insects collected belonged to the family Aphrophoridae, but also many species of leafhopper were identified. Overall, in Tuscany four species were the most represented: Philaenus spumarius(L.), Cicadella viridis(L.), Synophropsis lauri (Horvath) and Neophilaenus campestris(Fallen).In 2018 an outbreak of X. fastidiosa subsp. multiplex was reported in Monte Argentario (Grosseto province, Tuscany). In 2019 X. fastidiosa subspecies multiplex ST 87 was detected in seven P. spumarius and three N. campestris collected from the infected area.
35
SHERMAN, A. "MAGNETIC RESPONSE OF Pr1-xLaCexCuO4 IN COMPARISON WITH HOLE-DOPED CUPRATES". SPIN 04, n. 01 (marzo 2014): 1440006. http://dx.doi.org/10.1142/s2010324714400062.
Testo completoAbstract (sommario):
The origin of differences in the magnetic responses of Pr 1-x LaCe x CuO 4 with x = 0.11–0.12 and moderately doped p-type cuprates is investigated using the t–J model, the Mori projection operator technique and dispersions of charge carriers derived from photoemission experiments. These differences are related to the proximity of the former crystal to the boundary of the antiferromagnetic (AF) phase and to the remoteness of p-type compounds from it. This leads to different nesting vectors of the low-frequency equi-energy contours of carrier dispersions in these crystals. The strong nesting with the AF momentum as the nesting vector produces the commensurate low-frequency response and the coexistence of two spin-excitation branches in Pr 1-x LaCe x CuO 4, while incommensurate nesting vectors in p-type crystals lead to the incommensurate low-frequency response and the hourglass dispersion of susceptibility maxima.
36
Tsamparlis, Michael, e Aniekan Magnus Ukpong. "Lie Symmetries of the Wave Equation on the Sphere Using Geometry". Dynamics 4, n. 2 (29 aprile 2024): 322–36. http://dx.doi.org/10.3390/dynamics4020019.
Testo completoAbstract (sommario):
A semilinear quadratic equation of the form Aij(x)uij=Bi(x,u)ui+F(x,u) defines a metric Aij; therefore, it is possible to relate the Lie point symmetries of the equation with the symmetries of this metric. The Lie symmetry conditions break into two sets: one set containing the Lie derivative of the metric wrt the Lie symmetry generator, and the other set containing the quantities Bi(x,u),F(x,u). From the first set, it follows that the generators of Lie point symmetries are elements of the conformal algebra of the metric Aij, while the second set serves as constraint equations, which select elements from the conformal algebra of Aij. Therefore, it is possible to determine the Lie point symmetries using a geometric approach based on the computation of the conformal Killing vectors of the metric Aij. In the present article, the nonlinear Poisson equation Δgu−f(u)=0 is studied. The metric defined by this equation is 1 + 2 decomposable along the gradient Killing vector ∂t. It is a conformally flat metric, which admits 10 conformal Killing vectors. We determine the conformal Killing vectors of this metric using a general geometric method, which computes the conformal Killing vectors of a general 1+(n−1) decomposable metric in a systematic way. It is found that the nonlinear Poisson equation Δgu−f(u)=0 admits Lie point symmetries only when f(u)=ku, and in this case, only the Killing vectors are admitted. It is shown that the Noether point symmetries coincide with the Lie point symmetries. This approach/method can be used to study the Lie point symmetries of more complex equations and with more degrees of freedom.
37
Sun, Quan, Junxing Zheng, Hantao He e Zhaochao Li. "Characterizing Fabric Anisotropy of Air-Pluviated Sands". E3S Web of Conferences 92 (2019): 01003. http://dx.doi.org/10.1051/e3sconf/20199201003.
Testo completoAbstract (sommario):
Sand particles depositing through air generally align their largest dimensions in horizontal plane, forming a cross anisotropic fabric. Therefore, sands display varying strength, permeability, compressibility with directions. This study characterizes fabric anisotropy in loose and dense air-pluviated sand specimens scanned by X-ray Computed Tomography (X-ray CT) using a series of image processing techniques. The principal component analysis, three-dimensional watershed analysis, and Delaunay triangulation technique are used to compute directional parameters, including particle long axes, contact normals, and branch vectors, and scalar parameters, including index void ratios, coordination number, and average branch vector length. The particle long axes and branch vectors displayed preferred horizontal directions while the contact normals displayed preferred vertical directions. The dense specimen has smaller index void ratios, larger coordination number, and smaller average branch vector length than the loose specimen.
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Throm, Robert E., Annastasia A. Ouma, Sheng Zhou, Anantharaman Chandrasekaran, Timothy Lockey, Michael Greene, Suk See De Ravin et al. "Efficient construction of producer cell lines for a SIN lentiviral vector for SCID-X1 gene therapy by concatemeric array transfection". Blood 113, n. 21 (21 maggio 2009): 5104–10. http://dx.doi.org/10.1182/blood-2008-11-191049.
Testo completoAbstract (sommario):
AbstractRetroviral vectors containing internal promoters, chromatin insulators, and self-inactivating (SIN) long terminal repeats (LTRs) may have significantly reduced genotoxicity relative to the conventional retroviral vectors used in recent, otherwise successful clinical trials. Large-scale production of such vectors is problematic, however, as the introduction of SIN vectors into packaging cells cannot be accomplished with the traditional method of viral transduction. We have derived a set of packaging cell lines for HIV-based lentiviral vectors and developed a novel concatemeric array transfection technique for the introduction of SIN vector genomes devoid of enhancer and promoter sequences in the LTR. We used this method to derive a producer cell clone for a SIN lentiviral vector expressing green fluorescent protein, which when grown in a bioreactor generated more than 20 L of supernatant with titers above 107 transducing units (TU) per milliliter. Further refinement of our technique enabled the rapid generation of whole populations of stably transformed cells that produced similar titers. Finally, we describe the construction of an insulated, SIN lentiviral vector encoding the human interleukin 2 receptor common γ chain (IL2RG) gene and the efficient derivation of cloned producer cells that generate supernatants with titers greater than 5 × 107 TU/mL and that are suitable for use in a clinical trial for X-linked severe combined immunodeficiency (SCID-X1).
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Farigoule, Pauline, Marguerite Chartois, Xavier Mesmin, Maxime Lambert, Jean-Pierre Rossi, Jean-Yves Rasplus e Astrid Cruaud. "Vectors as Sentinels: Rising Temperatures Increase the Risk of Xylella fastidiosa Outbreaks". Biology 11, n. 9 (31 agosto 2022): 1299. http://dx.doi.org/10.3390/biology11091299.
Testo completoAbstract (sommario):
Global change is expected to modify the threat posed by pathogens to plants. However, little is known regarding how a changing climate will influence the epidemiology of generalist vector-borne diseases. We developed a high-throughput screening method to test for the presence of a deadly plant pathogen, Xylella fastidiosa, in its insect vectors. Then, using data from a four-year survey in climatically distinct areas of Corsica (France), we demonstrated a positive correlation between the proportion of vectors positive to X. fastidiosa and temperature. Notably, a higher prevalence corresponded with milder winters. Our projections up to 2100 indicate an increased risk of outbreaks. While the proportion of vectors that carry the pathogen should increase, the climate conditions will remain suitable for the bacterium and its main vector, with possible range shifts towards a higher elevation. Besides calling for research efforts to limit the incidence of plant diseases in the temperate zone, this work reveals that recent molecular technologies could and should be used for massive screening of pathogens in vectors to scale-up surveillance and management efforts.
40
Trobridge, Grant D., Daniel G. Miller, Michael A. Jacobs, James M. Allen, Erik Olson, Hans-Peter Kiem, Rajinder Kaul e David W. Russell. "Large Scale Analysis of Foamy Virus Vector Integration Sites in Human CD34+ Cells." Blood 104, n. 11 (16 novembre 2004): 496. http://dx.doi.org/10.1182/blood.v104.11.496.496.
Testo completoAbstract (sommario):
Abstract The ability of retroviruses to efficiently integrate into the host cell’s genome has led to their use as gene delivery vehicles for gene therapy. However, integration in the genome can have adverse effects as observed in a gene therapy trial for X-linked SCID using an oncoretroviral vector. Recent studies have shown that an oncoretroviral vector integrated preferentially near transcription start sites and that a lentiviral vector integrated preferentially within genes. Foamy viruses are integrating retroviruses with many properties that distinguish them from onco- or lentiviruses, perhaps the most important characteristic for gene therapy being that they are non-pathogenic. We previously showed that foamy vectors efficiently transduce CD34+ SCID mouse-repopulating cells (SRCs) from human mobilized peripheral blood, demonstrating their potential for hematopoietic stem cell gene therapy. We present here the first large-scale analysis of foamy vector integration sites. Integration sites were determined by infecting human CD34+ cells or normal fibroblasts with a foamy vector carrying a bacterial origin of replication, then rescuing plasmids containing vector provirus-genomic junction sites in bacteria, and sequencing the foamy vector LTR-human genome junctions. Over 1900 unique integration sites in human CD34+ cells and 1000 unique sites in normal human fibroblasts were mapped using the human genome database. The foamy vector did not integrate preferentially into genes. The percentage of integration sites within Refseq genes in human CD34+ cells, human fibroblasts and randomly generated sites was 29, 23, and 32% respectively. Foamy vectors showed only a slight preference for integration within 1 kb 5′ or 3′ of Refseq transcription start sites. In summary, our data show that foamy vectors have a distinct integration site profile relative to oncoretroviral and lentiviral vectors. Future studies will be required to determine if the unique integration site preference of foamy vectors translates into a reduced risk for oncogenesis in gene therapy applications.
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Naumann, Nora, Suk See De Ravin, Uimook Choi, Morvarid Moayeri, Yasuhiro Ikeda e Harry L. Malech. "Correction of Human X-Linked Chronic Granulomatous Disease (X-CGD) Following Transduction of X-CGD CD34+ Cells with a Modified RD114-Pseudotyped Simian Immunodeficiency Virus Lentiviral Vector in a NOD/SCID Mouse Xenograft Model." Blood 108, n. 11 (16 novembre 2006): 3278. http://dx.doi.org/10.1182/blood.v108.11.3278.3278.
Testo completoAbstract (sommario):
Abstract X-linked chronic granulomatous disease (X-CGD) is an immune deficiency that results from mutations in the gp91phox subunit of the phagocyte NADPH-oxidase. We have developed a modified RD114-pseudotyped simian immunodeficiency virus (SIVmac) vector encoding human gp91phox and report here that this vector efficiently targets peripheral blood-mobilized CD34+ hematopoietic stem cells (PBSCs) from X-CGD patients, correcting the oxidase deficient phenotype. The majority of lentiviral gene transfer studies have relied on human immunodeficiency virus (HIV) 1-derived vectors pseudotyped with the vesicular stomatitis virus G protein (VSV-G) envelope. Because HIV is a human pathogen, there are theoretical benefits to considering other types of lentivectors engineered from viruses less pathogenic for humans such as SIV-based vectors. In addition, the VSV-G envelope has some toxicity for cells, limiting the titers of vector that can be used. RD114/TR-pseudotyped SIV gp91phox encoding vector particles were transiently produced following transfection of 293T cells and concentrated by high-speed centrifugation achieving stock titers of 1.5 × 10E7 infectious units/ml. PBSCs from two patients with X-CGD (P1 and P2) were cultured and transduced (multiplicity of infection 2–3) overnight four times before transplantation into sublethally irradiated NOD/SCID mice on day 5 of culture. Ex vivo transduction efficiency was 40.5% and 46%, respectively. Cells maintained in culture showed a progressive decrease in marking over the first 9 days, after which marking stabilized at 22.7% (P1) and 27.1% (P2) out to day 26 of culture with an averaged copy number of 2.2–2.4 per transduced cell at that time. Compared to healthy control, 18–19% of myeloid colonies derived from patient CD34+ cells stained positive in the nitroblue tetrazolium (NBT) test. Liquid cell cultures at 20 days were analyzed for production of reactive oxidative species using the flow cytometry dihydrorhodamine 123 (DHR) assay. Cells from P1 demonstrated 15.3% and from P2 9.1% of the activity of healthy cells. At 6 weeks after transplant, analysis of mouse bone marrow (mBM) samples revealed human cell engraftment levels of 36.8–74% (CD45+ cells). Compared to analysis of mice transplanted with healthy human PBSCs, 10.5% (P1) and 7.3% (P2) of the myeloid cells (CD13+) developing from X-CGD CD34+ cells in the chimeric mBM expressed gp91phox transgene. Human CD34+ cells were isolated from mBM and grown in liquid culture or plated for colony assays. 2.1% (P1) and 1.2% (P2) of cultured cells were gp91phox positive at day 14 with an averaged copy number of 2.3–5.2 per marked cell. 4.8% and 3.6% of colonies derived from the same cells were positive in the NBT test. DHR assay at day 21 of culture demonstrated 2.7% (P1) and 2.0% (P2) of the activity of healthy cells. Linear amplification-mediated PCR retrieved multiple unique vector insertion sites in CD34+ cells from both patients isolated from chimeric mBM, without predominance of any one clone suggesting polyclonal marking. In conclusion, these data suggest that modified RD114-pseudotyped SIVmac-based vectors may be suitable for hematopoietic gene therapy for CGD and represent an alternative to HIV-1 based vectors. Studies are ongoing to further improve vector production titers to achieve higher transduction levels of PBSCs.
42
Li, D. Y., e C. W. MacKinnon. "Indexing of incommensurate satellite reflections in X-ray powder diffraction pattern of (Bi, Pb)2Sr2Ca2Cu3Ox (2223) phase". Powder Diffraction 12, n. 3 (settembre 1997): 141–44. http://dx.doi.org/10.1017/s088571560000960x.
Testo completoAbstract (sommario):
X-ray powder diffraction data and refined unit cell parameters for the (Bi, Pb)2Sr2Ca2Cu3Ox (2223) superconducting phase, indexed using incommensurate modulation principles, are reported. Comparison of the results obtained with one- and two-component modulation wave vectors showed that the two-component modulation wave vector is superior for indexing the satellite reflections. A two-component wave vector indexing result seems likely when only the powder diffraction data are considered.
43
Ling, Huixuan, Tian Gao, Tao Gong, Jiangzhao Wu e Liang Zou. "Hydraulic Rock Drill Fault Classification Using X−Vectors". Mathematics 11, n. 7 (4 aprile 2023): 1724. http://dx.doi.org/10.3390/math11071724.
Testo completoAbstract (sommario):
Hydraulic rock drills are widely used in drilling, mining, construction, and engineering applications. They typically operate in harsh environments with high humidity, large temperature differences, and vibration. Under the influence of environmental noise and operational patterns, the distributions of data collected by sensors for different operators and equipment differ significantly, which leads to difficulty in fault classification for hydraulic rock drills. Therefore, an intelligent and robust fault classification method is highly desired. In this paper, we propose a fault classification technique for hydraulic rock drills based on deep learning. First, considering the strong robustness of x−vectors to the features extracted from the time series, we employ an end−to−end fault classification model based on x−vectors to realize the joint optimization of feature extraction and classification. Second, the overlapping data clipping method is applied during the training process, which further improves the robustness of our model. Finally, the focal loss is used to focus on difficult samples, which improves their classification accuracy. The proposed method obtains an accuracy of 99.92%, demonstrating its potential for hydraulic rock drill fault classification.
44
Shimizu, Y., B. Koller, D. Geraghty, H. Orr, S. Shaw, P. Kavathas e R. DeMars. "Transfer of cloned human class I major histocompatibility complex genes into HLA mutant human lymphoblastoid cells". Molecular and Cellular Biology 6, n. 4 (aprile 1986): 1074–87. http://dx.doi.org/10.1128/mcb.6.4.1074-1087.1986.
Testo completoAbstract (sommario):
Three new kinds of recombinant DNA constructs were used to transfer cloned human class I HLA genes (A2 and B8) into unique HLA mutant lymphoblastoid cells: pHeBo(x): a class I gene, "x," in plasmid vector pHeBo, which contains a hygromycin resistance gene and Epstein-Barr virus oriP element that sustains extrachromosomal replication; pHPT(x): gene x in a vector with a hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene; pHPTe(x): gene x in a vector with the HPRT gene and oriP element. Cell surface class I antigen expression was strong in transferents made with class I-deficient lymphoblastoid cell line mutants .144 (A-null), .53 (B-null), and .184 (A-null, B-null). Transferents expressing HLA-A2 were recognized specifically by HLA-A2-specific cytotoxic T lymphocytes. When introduced on either of the vectors with the Epstein-Barr virus oriP element, the class I gene replicated extrachromosomally and was lost at rates of 0.2 to 0.3 per cell division. When introduced with vector pHPT (lacking Epstein-Barr virus oriP), the B8 gene was inserted at different chromosomal locations. Introduction of the HLA-B8 gene failed to restore antigen expression by HLA-B-null mutant .174, providing evidence that, unlike mutants exemplified by .53, .144, and .184, some HLA antigen loss mutants are deficient in a trans-acting function needed for class I antigen expression. Of more general interest, the results obtained with HLA class I genes in vectors that replicate extrachromosomally suggest ways of relating genic expression to chromatin structure and function and of attempting to clone functional human centromeres.
45
Shimizu, Y., B. Koller, D. Geraghty, H. Orr, S. Shaw, P. Kavathas e R. DeMars. "Transfer of cloned human class I major histocompatibility complex genes into HLA mutant human lymphoblastoid cells." Molecular and Cellular Biology 6, n. 4 (aprile 1986): 1074–87. http://dx.doi.org/10.1128/mcb.6.4.1074.
Testo completoAbstract (sommario):
Three new kinds of recombinant DNA constructs were used to transfer cloned human class I HLA genes (A2 and B8) into unique HLA mutant lymphoblastoid cells: pHeBo(x): a class I gene, "x," in plasmid vector pHeBo, which contains a hygromycin resistance gene and Epstein-Barr virus oriP element that sustains extrachromosomal replication; pHPT(x): gene x in a vector with a hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene; pHPTe(x): gene x in a vector with the HPRT gene and oriP element. Cell surface class I antigen expression was strong in transferents made with class I-deficient lymphoblastoid cell line mutants .144 (A-null), .53 (B-null), and .184 (A-null, B-null). Transferents expressing HLA-A2 were recognized specifically by HLA-A2-specific cytotoxic T lymphocytes. When introduced on either of the vectors with the Epstein-Barr virus oriP element, the class I gene replicated extrachromosomally and was lost at rates of 0.2 to 0.3 per cell division. When introduced with vector pHPT (lacking Epstein-Barr virus oriP), the B8 gene was inserted at different chromosomal locations. Introduction of the HLA-B8 gene failed to restore antigen expression by HLA-B-null mutant .174, providing evidence that, unlike mutants exemplified by .53, .144, and .184, some HLA antigen loss mutants are deficient in a trans-acting function needed for class I antigen expression. Of more general interest, the results obtained with HLA class I genes in vectors that replicate extrachromosomally suggest ways of relating genic expression to chromatin structure and function and of attempting to clone functional human centromeres.
46
Friantika, Khasnah Aris, Harina O. L. Monim e Rium Hilum. "MATRIKS BAKU UNTUK TRANSFORMASI LINIER PADA RUANG VEKTOR DIMENSI TIGA". Jurnal Natural 15, n. 2 (1 ottobre 2019): 88–93. http://dx.doi.org/10.30862/jn.v15i2.140.
Testo completoAbstract (sommario):
The linear transformation is a function relating the vector ke . If , then the transformation is called a linear operator. Several examples of linear operators have been introduced since SMA such as reflexive, rotation, compression and expansion and shear. Apart from being introduced in SMA, these linear operators were also introduced to the linear algebra course. Linear transformations studied at the university level include linear transformation in finite dimension vector spaces . The discussion includes how to determine the standard matrix for reflexive linear transformations, rotation, compression and expansion and given shear. Through the column vectors of reflexive, rotation, compression and expansion and shear, a standard matrix of 2x2 size is formed for the corresponding linear transformation. however, in this study, the authors studied linear transformations in dimensioned vector spaces . The results of this study are if known is a vector space with finite and the standard matrix for reflexivity, rotation, expansion, compression and shear is obtained. Each of these linear transformations is performed on x-axis, y-axis and z-axis on to get column vectors. The column vectors as a result of the linear transformation at form the standard matrix for the corresponding linear transformation in the vector space. The standard matrix for linear transformations in the vector space is obtained by determining reflexivity, rotation, expansion, compression and shear. The process of obtaining a standard matrix for linear transformation is carried out by rewriting the standard basis, determining the column vectors, and rearranging them as the standard matrix for each linear transformation in the vector space
47
Baxter, Laurence A., e Seung Min Lee. "Structure functions with finite minimal vector sets". Journal of Applied Probability 26, n. 1 (marzo 1989): 196–201. http://dx.doi.org/10.2307/3214331.
Testo completoAbstract (sommario):
A continuum structure function (CSF) y is a non-decreasing mapping from the unit hypercube to the unit interval. Define whereas γ (γ) < α for all y < x}, the set of minimal vectors to level α. This paper examines CSFs for which each Pα is finite. It is shown that if γ is such a CSF and X is a vector of independent random variables, the distribution of γ (X) is readily calculated. Further, if γ is an arbitrary right-continuous CSF, the distribution of γ (X) may be approximated arbitrarily closely by that of γ′(X) where γ′ is a right-continuous CSF for which each minimal vector set is finite.
48
Baxter, Laurence A., e Seung Min Lee. "Structure functions with finite minimal vector sets". Journal of Applied Probability 26, n. 01 (marzo 1989): 196–201. http://dx.doi.org/10.1017/s0021900200041942.
Testo completoAbstract (sommario):
A continuum structure function (CSF) y is a non-decreasing mapping from the unit hypercube to the unit interval. Define whereas γ (γ) < α for all y < x}, the set of minimal vectors to level α. This paper examines CSFs for which each Pα is finite. It is shown that if γ is such a CSF and X is a vector of independent random variables, the distribution of γ (X) is readily calculated. Further, if γ is an arbitrary right-continuous CSF, the distribution of γ (X) may be approximated arbitrarily closely by that of γ′(X) where γ′ is a right-continuous CSF for which each minimal vector set is finite.
49
Nataraj, P. S. V., e Sachin Tharewal. "An Interval Analysis Algorithm for Automated Controller Synthesis in QFT Designs". Journal of Dynamic Systems, Measurement, and Control 129, n. 3 (26 maggio 2006): 311–21. http://dx.doi.org/10.1115/1.2397147.
Testo completoAbstract (sommario):
In this paper, an interval analysis algorithm is proposed for the automatic synthesis of fixed structure controllers in quantitative feedback theory (QFT). The proposed algorithm is tested on several examples and compared with the controller designs given in the QFT literature. Compared to the existing methods for QFT controller synthesis, the proposed algorithm yields considerable improvement in the high frequency gain of the controller in all examples, and improvements in the cutoff frequency of the controller in all but one examples. Notation: R denotes the field of real numbers, Rn is the vector space of column vectors of length n with real entries. A real closed nonempty interval is a one-dimensional box, i.e., a pair x=[x̱,x¯] consisting of two real numbers x̱ and x¯ with x̱⩽x¯. The set of all intervals is IR. A box may be considered as an interval vector x=(x1,…,xn)T with components xk=[x̱k,x¯k]. A box x can also be identified as a pair x=[x̱,x¯] consisting of two real column vectors x̱ and x¯ of length n with x̱⩽x¯. A vector x∊Rn is contained in a box x, i.e., x∊x iff x̱⩽x⩽x¯. The set of all boxes of dimension n is IRn. The width of a box x is wid x=x¯−x̱. The range of a function f:Rn→R over a box x is range(f,x)={f(x)∣x∊x}. A natural interval extension of f on the box x is obtained by replacing in the expression for f, all occurrences of reals xi with intervals xi and all real operations with the corresponding interval operations. The natural interval evaluation of f on x is written as f(x). The interval function f(x) is said to be of convergent of order α if widf(x)−wid{range(f,x)}⩽c{widx}α. By the inclusion property of interval arithmetic, range (f,x)⊆f(x).
50
Masuda, Shigeo, Tomoyuki Abe, Makoto Inoue, Mamoru Hasegawa, Satoshi Hayashi, Yoshikazu Nagao e Yutaka Hanazono. "Safe and Efficient Expansion of Human HSC with Sendai Virus Vector Expressing HoxB4 in Fetal Sheep." Blood 114, n. 22 (20 novembre 2009): 693. http://dx.doi.org/10.1182/blood.v114.22.693.693.
Testo completoAbstract (sommario):
Abstract Abstract 693 Background: Homeobox B4 (HoxB4) has been shown to be a potent stem cell self-renewal gene, especially in hematopoietic stem cells (HSC). Accumulating evidence from murine studies indicates that the overexpression of HoxB4 enhances in vivo and ex vivo expansion of HSC. Although no leukemia has been observed after transplantation of HoxB4-transduced cells in murine models, the study using large animals such as dogs and non-human primates with retroviral vectors expressing HoxB4 showed the frequent development of leukemia. Regarding retroviral vectors expressing HoxB4, there is another concern, that is, insertional leukemogenesis, which has been elucidated in the hematopoietic stem cell gene therapy for X-SCID. To avoid the insertional mutagenesis, other vectors may be considered, including Epstein-Barr nuclear antigen (EBNA)-1 based episomal vectors or the transposon; however, problems are left, i.e. low transduction efficiency with EBNA vectors and unclear safety with transposon vectors. To avoid both the persistent HoxB4 expression and insertional mutagenesis leading to leukemogenesis, we have developed a new type of Sendai virus (SeV) vector; it lacks the polymerase gene, namely P-defective SeV (SeV/δP) vector. SeV is an enveloped virus with a non-segmented, negative-stranded RNA genome. SeV-based vectors are non-integrating, cytoplasmic vectors. They replicate exclusively in the cytoplasm of transduced cells, and do not go through a DNA phase; therefore, there is no concern about the unwanted integration of foreign sequences into chromosomal DNA of the host. We have previously shown that the transduction efficiency of human CD34+ cells with the SeV vector was very high; around 70% (100 multiplicity of infections). On the other hand, SeV/δP vectors are incapable of self-replication, thus enabling transient gene expression without spoiling their ability to efficiently transduce CD34+ cells. Here, using the SeV/δP vector expressing HoxB4 (SeV/δP/HoxB4 vector), we examined the effectiveness and safety of human HSC expansion after in utero transplantation to fetal sheep. Methods: After enrichment of CD34+ cells from cryopreserved human umbilical cord blood, these cells were repeatedly exposed to SeV/δP/HoxB4 vector every 24 h for 4 days. The transduced cells (3.2–11.7 × 105) were transplanted into the abdominal cavity of fetal sheep at 45–50 gestational days (full term, 147 days) that have premature immune system (HoxB4 group, n = 4; control group, n = 4). The engraftment of hematopoietic cells derived from human HSC in the lambs after birth was quantitatively evaluated by colony PCR of the bone marrow. The development of leukemia was assessed by regular sampling of peripheral blood and bone marrow. Results: The human–sheep chimeric ratio in the bone marrow of HoxB4 group was calculated 4.8-times higher than that of control group after birth, as assessed by colony PCR. The SeV genome was no longer detectable in the bone marrow and peripheral blood of lambs as assessed by RNA-PCR, confirming the SeV vectors were cleared. No leukemia developed in any of the sheep in either group at present (at 12 months after transplantation). Conclusion: The SeV/δP vector would be suitable for transient expression of HoxB4 in human CD34+ cells, enabling 4.8-times expansion of human HSC as assessed by their repopulating ability in sheep. The expansion of human HSC with the SeV vector was comparable to that with HoxB4-retroviral vectors. In addition, the SeV/δP vector is free of concern about transgene-related and insertional leukemogenesis and should be safer than retroviral vectors. Disclosures: No relevant conflicts of interest to declare.