Journal articles: 'Matrix Analysis and Positivity'

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Bhatia, Rajendra, and Ludwig Elsner. "Positivity Preserving Hadamard Matrix Functions." Positivity 11, no. 4 (September 26, 2007): 583–88. http://dx.doi.org/10.1007/s11117-007-2104-8.

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Bernik, Janez, Mitja Mastnak, and Heydar Radjavi. "Positivity and matrix semigroups." Linear Algebra and its Applications 434, no. 3 (February 2011): 801–12. http://dx.doi.org/10.1016/j.laa.2010.09.045.

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ter Horst, S., and A. van der Merwe. "Linear matrix maps for which positivity and complete positivity coincide." Linear Algebra and its Applications 628 (November 2021): 140–81. http://dx.doi.org/10.1016/j.laa.2021.07.007.

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Mørken, Knut M. "On Total Positivity of the Discrete Spline Collocation Matrix." Journal of Approximation Theory 84, no. 3 (March 1996): 247–64. http://dx.doi.org/10.1006/jath.1996.0018.

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Gross, Kenneth I., and Donald St P. Richards. "Total positivity, spherical series, and hypergeometric functions of matrix argument." Journal of Approximation Theory 59, no. 2 (November 1989): 224–46. http://dx.doi.org/10.1016/0021-9045(89)90153-6.

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Horváth, Zoltán. "On the positivity of matrix-vector products." Linear Algebra and its Applications 393 (December 2004): 253–58. http://dx.doi.org/10.1016/j.laa.2004.03.012.

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Melkman, Avraham A. "Another Proof of the Total Positivity of the Discrete Spline Collocation Matrix." Journal of Approximation Theory 84, no. 3 (March 1996): 265–73. http://dx.doi.org/10.1006/jath.1996.0019.

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Johnson, Charles R., and Sivaram K. Narayan. "When the positivity of the leading principal minors implies the positivity of all principal minors of a matrix." Linear Algebra and its Applications 439, no. 10 (November 2013): 2934–47. http://dx.doi.org/10.1016/j.laa.2013.08.017.

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Habel, Azza F., Rabeb M. Ghali, Hanen Bouaziz, Amira Daldoul, Mariem Hadj-Ahmed, Amina Mokrani, Sonia Zaied, et al. "Common matrix metalloproteinase-2 gene variants and altered susceptibility to breast cancer and associated features in Tunisian women." Tumor Biology 41, no. 4 (April 2019): 101042831984574. http://dx.doi.org/10.1177/1010428319845749.

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A role for matrix metalloproteinase polymorphisms in breast cancer development and progression was proposed, but with inconclusive results. We assessed the relation of matrix metalloproteinase-2 variants with breast cancer and related phenotypes in Tunisians. This case-control retrospective study involved 430 women with breast cancer and 498 healthy controls. Genotyping of matrix metalloproteinase-2 rs243866, rs243865, rs243864, and rs2285053 was analyzed by allelic exclusion. The minor allele frequency of rs2285053 was significantly lower in women with breast cancer cases as compared to control women; minor allele frequencies of the remaining single-nucleotide polymorphisms were similar between cases and control women. The distribution of rs243865 and rs2285053 genotypes was significantly different between breast cancer patients and control subjects. This persisted when key covariates were controlled for. None of the matrix metalloproteinase-2 variants were associated with estrogen receptor positivity, progesterone receptor positivity, or with double estrogen receptor–progesterone receptor positivity in breast cancer patients. Matrix metalloproteinase-2 rs243866, rs243865, and rs243864 were positively associated with menstrual irregularity and histological type, while rs243866 and rs2285053 were negatively associated with menarche and nodal status. In addition, rs2285053 was negatively associated with triple negativity, tumor size, distance metastasis, molecular type, and chemotherapy. Haploview analysis revealed high linkage disequilibrium between matrix metalloproteinase-2 variants. Four-locus Haploview analysis identified haplotypes GCTT and GTTC to be negatively associated with breast cancer, which remained statistically after controlling for key covariates. Matrix metalloproteinase-2 alleles and genotypes, along with four-locus haplotypes, are related to reduced susceptibility to breast cancer in Tunisian women, suggesting a protective effect.

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Osada, Hirofumi. "Positivity of the self-diffusion matrix of interacting Brownian particles with hard core." Probability Theory and Related Fields 112, no. 1 (September 17, 1998): 53–90. http://dx.doi.org/10.1007/s004400050183.

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Gadoev, M. G., and S. I. Konobulov. "Conditions for the Positivity and Coercive Solvability of the Matrix Schrödinger Operator in Banach Spaces of Vector Functions." Differential Equations 39, no. 6 (June 2003): 899–900. http://dx.doi.org/10.1023/b:dieq.0000008418.01640.0d.

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Farenick, Douglas, and Michelle McBurney. "Toeplitz separability, entanglement, and complete positivity using operator system duality." Proceedings of the American Mathematical Society, Series B 10, no. 10 (April 10, 2023): 114–28. http://dx.doi.org/10.1090/bproc/163.

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A new proof is presented of a theorem of L. Gurvits [LANL Unclassified Technical Report (2001), LAUR–01–2030], which states that the cone of positive block-Toeplitz matrices with matrix entries has no entangled elements. The proof of the Gurvits separation theorem is achieved by making use of the structure of the operator system dual of the operator system C ( S 1 ) ( n ) C(S^1)^{(n)} of n × n n\times n Toeplitz matrices over the complex field, and by determining precisely the structure of the generators of the extremal rays of the positive cones of the operator systems C ( S 1 ) ( n ) ⊗ min B ( H ) C(S^1)^{(n)}\otimes _{\text {min}}\mathcal {B}(\mathcal {H}) and C ( S 1 ) ( n ) ⊗ min B ( H ) C(S^1)_{(n)}\otimes _{\text {min}}\mathcal {B}(\mathcal {H}) , where H \mathcal {H} is an arbitrary Hilbert space and C ( S 1 ) ( n ) C(S^1)_{(n)} is the operator system dual of C ( S 1 ) ( n ) C(S^1)^{(n)} . Our approach also has the advantage of providing some new information concerning positive Toeplitz matrices whose entries are from B ( H ) \mathcal {B}(\mathcal {H}) when H \mathcal {H} has infinite dimension. In particular, we prove that normal positive linear maps ψ \psi on B ( H ) \mathcal {B}(\mathcal {H}) are partially completely positive in the sense that ψ ( n ) ( x ) \psi ^{(n)}(x) is positive whenever x x is a positive n × n n\times n Toeplitz matrix with entries from B ( H ) \mathcal {B}(\mathcal {H}) . We also establish a certain factorisation theorem for positive Toeplitz matrices (of operators), showing an equivalence between the Gurvits approach to separation and an earlier approach of T. Ando [Acta Sci. Math. (Szeged) 31 (1970), pp. 319–334] to universality.

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Khusainov, D. Ya, J. Diblík, Z. Svoboda, and Z. Šmarda. "Instable Trivial Solution of Autonomous Differential Systems with Quadratic Right-Hand Sides in a Cone." Abstract and Applied Analysis 2011 (2011): 1–23. http://dx.doi.org/10.1155/2011/154916.

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The present investigation deals with global instability of a generaln-dimensional system of ordinary differential equations with quadratic right-hand sides. The global instability of the zero solution in a given cone is proved by Chetaev's method, assuming that the matrix of linear terms has a simple positive eigenvalue and the remaining eigenvalues have negative real parts. The sufficient conditions for global instability obtained are formulated by inequalities involving norms and eigenvalues of auxiliary matrices. In the proof, a result is used on the positivity of a general third-degree polynomial in two variables to estimate the sign of the full derivative of an appropriate function in a cone.

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FANNES, M., B. NACHTERGAELE, and L. SLEGERS. "FUNCTIONS OF MARKOV PROCESSES AND ALGEBRAIC MEASURES." Reviews in Mathematical Physics 04, no. 01 (March 1992): 39–64. http://dx.doi.org/10.1142/s0129055x92000030.

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We introduce a class of translation-invariant measures on the set {0, …, q−1}ℤ determined by a set of q d-dimensional matrices. They are algebraic in the sense that their densities are obtained by applying a functional to products of the defining matrices. Positivity of probabilities is assured by assuming a positivity structure on the algebra of defining matrices. Restricting attention to the usual positivity notion of positive matrix elements, a detailed analysis leads to a canonical representation theorem that solves the parametrization problem. Furthermore, we show that the class of algebraic measures coincides with the class of functions of Markov processes with finite state spaces. Our main result consists in the detailed study of the asymptotics of the conditional probabilities from which we derive a formula for the mean entropy.

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Tiwari, Bhupendra Nath, Jude Kuipo Kibindé, Neeraj Gupta, Mahdi Khosravy, and Stefano Bellucci. "Optimization of Optical Instruments Under Fluctuations of System Parameters." International Journal of Ambient Computing and Intelligence 12, no. 1 (January 2021): 73–113. http://dx.doi.org/10.4018/ijaci.2021010104.

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Optimization plays a fundamental role in understanding stability characteristics of optical systems, for example, lenses, mirrors, and their constrained counterparts. For a dynamical object, the authors address the issue of stability of an image formed under fluctuations of optimization variables. As per this analysis, for a given single lens, mirror, or optical instrument, the positivity of pure correlation components of the fluctuation matrix characterizes the local stability about a chosen fixed point, whilst the positivity of the determinant of the fluctuation matrix offers global stability of the image under variations of the object distance and lateral magnification. In this paper, they demonstrate that there exists a clear cut distinction between the positive and negative lenses and mirrors about the line of unit lateral magnification. Moreover, they propose the extension of the above model to a class of constraint optical system optimization. They also propose an extended formulation for an optimized designing of nonlinearly constrained optical systems with finitely many components.

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Fantaye, Abayneh Kebede, and Zerihun Kinfe Birhanu. "Mathematical Model and Analysis of Corruption Dynamics with Optimal Control." Journal of Applied Mathematics 2022 (January 12, 2022): 1–16. http://dx.doi.org/10.1155/2022/8073877.

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In this study, a deterministic mathematical model that explains the transmission dynamics of corruption is proposed and analyzed by considering social influence on honest individuals. Positivity and boundedness of solution of the model are proved and basic reproduction number R 0 is computed using the next-generation matrix method. The analysis shows that corruption-free equilibrium is locally and globally asymptotically stable whenever R 0 < 1 . Also, the endemic equilibrium point is locally and globally asymptotically stable whenever R 0 > 1 . Then, the model was extended to optimal control, and some numerical simulations with and without optimal control are also performed to verify the theoretical analysis using MATLAB. Numerical simulation of optimal control model shows that the prevention and punishment strategy is the most effective strategy to reduce the dynamic transmission of corruption.

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Kazeko, Ludmila A., Viktoryia A. Zakharava, Julia D. Benesh, and Eugeny D. Cherstvoy. "Significance of Tissue Inhibitors of Matrix Metalloproteinases Expression in Pathogenesis and Differential Diagnosis of Periodontal Pathology." Annals of the Russian academy of medical sciences 78, no. 3 (July 3, 2023): 213–26. http://dx.doi.org/10.15690/vramn2041.

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Background. The balance of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) is crucial for the manifestation and progression of periodontal diseases and is one of the promising areas of scientific research in terms of developing methods for selective inhibition of MMPs. Aims to determine the significance of TIMP1 and TIMP2 expression parameters in gingival biopsies to identify the type of periodontitis at the stage of disease manifestation. Methods. A prospective study with parallel inclusion of patients with different forms of periodontitis in the compared groups was performed. The object of this study were patients with various forms of periodontitis. Pathological examination with morphometric analysis of TIMPs expression and subsequent statistical data analysis was performed using AperioImageScope v12.4.0.5043, Statistica 10.0, MedCalc19.6. Results. The study included 67 patients with aggressive (AgP, Grade C, n = 19), chronic simplex (CSP, Grade В, n = 10) and chronic complex (CCP, in the presence of occlusal trauma, Grade В, n = 38) periodontitis and 15 conditionally healthy patients (control group). The expression of TIMP1 and TIMP2 was detected with variable intensity both in the epithelium and in the stroma of the gingiva, and was significantly higher in periodontitis groups compared with the control group (MeTIMP1/2 = 32%/70%). Parameters of TIMP1 and TIMP2 expression had no significant differences in the groups with AgP (MeTIMP1/2 = 84%/98%) and CCP (MeTIMP1/2 = 83%/94%), except for higher parameters of the positivity of epithelial expression of TIMP2 (U = 61 372; p 0.05) and lower levels of intensity of its expression in AgP (MeAgP/CCP=180/171; U = 56 491; p 0.001). Correlation analysis revealed an inverse relationship of TIMPs expression parameters with those MMPs, including those most significant for the development of AgP MMP1 ( = 0.40), MMP8 ( = 0.34), and MMP14 ( = 0.24). ROC analysis established acceptable informativeness of all studied parameters of total expression and positivity of epithelial expression of TIMP1, as well as positivity of total expression and intensity of epithelial expression of TIMP2 to distinguish between aggressive and chronic forms of periodontitis at the stage of disease manifestation. Conclusion. Our results show an increase in the expression of TIMP1 and TIMP2 in various forms of periodontitis and an inverse relationship with the MMPs inhibited by them. This complements both the fundamental knowledge of the development and progression of periodontal pathology and may have applied significance in terms of using the studied TIMP1 and TIMP2 expression criteria to establish the aggressive course of periodontitis already at the stage of disease manifestation, which will allow to individualize treatment, prevent or slow down tooth loss in order to preserve and/or improve the quality of life of this patient group.

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Bennoui, Abdelhamid, Nabila Barrouk, and Mounir Redjouh. "Generalized Result on Global Existence of Weak Solutions for Parabolic Reaction-Diffusion Systems." International Journal of Analysis and Applications 21 (March 26, 2023): 30. http://dx.doi.org/10.28924/2291-8639-21-2023-30.

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In this paper, we study global existence of weak solutions for 2 × 2 parabolic reaction-diffusion systems with a full matrix of diffusion coefficients on a bounded domain, such as, we treat the main properties related: the positivity of the solutions and the total mass of the components are preserved with time. Moreover, we suppose that the non-linearities have critical growth with respect to the gradient. The technique used is based on compact semigroup methods and some estimates. Our objective is to show, under appropriate hypotheses, that the proposed model has a global solution with a large choice of non-linearities.

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Oja, Erkki, and Mark Plumbley. "Blind Separation of Positive Sources by Globally Convergent Gradient Search." Neural Computation 16, no. 9 (September 1, 2004): 1811–25. http://dx.doi.org/10.1162/0899766041336413.

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The instantaneous noise-free linear mixing model in independent component analysis is largely a solved problem under the usual assumption of independent nongaussian sources and full column rank mixing matrix. However, with some prior information on the sources, like positivity, new analysis and perhaps simplified solution methods may yet become possible. In this letter, we consider the task of independent component analysis when the independent sources are known to be nonnegative and well grounded, which means that they have a nonzero pdf in the region of zero. It can be shown that in this case, the solution method is basically very simple: an orthogonal rotation of the whitened observation vector into nonnegative outputs will give a positive permutation of the original sources. We propose a cost function whose minimum coincides with nonnegativity and derive the gradient algorithm under the whitening constraint, under which the separating matrix is orthogonal. We further prove that in the Stiefel manifold of orthogonal matrices, the cost function is a Lyapunov function for the matrix gradient flow, implying global convergence. Thus, this algorithm is guaranteed to find the nonnegative well-grounded independent sources. The analysis is complemented by a numerical simulation, which illustrates the algorithm.

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Gatselis, Nikolaos K., Kalliopi Zachou, George Giannoulis, Stella Gabeta, Gary L. Norman, and George N. Dalekos. "Serum Cartilage Oligomeric Matrix Protein and Golgi Protein-73: New Diagnostic and Predictive Tools for Liver Fibrosis and Hepatocellular Cancer?" Cancers 13, no. 14 (July 13, 2021): 3510. http://dx.doi.org/10.3390/cancers13143510.

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The cartilage oligomeric matrix protein (COMP) and Golgi-protein-73 (GP73) have been proposed as markers of liver fibrosis and hepatocellular carcinoma (HCC). Our aim was to assess the performance of the combination of these markers in diagnosing cirrhosis and predicting HCC development. Sera from 288 consecutive patients with chronic liver diseases were investigated by using COMP and GP73-ELISAs. Dual positivity for COMP (>15 U/L) and GP73 (>20 units) was observed in 24 (8.3%) patients, while 30 (10.4%) were GP73(+)/COMP(−), 37/288 (12.8%) GP73(−)/COMP(+), and 197 (68.5%) GP73(−)/COMP(−). Positivity for both markers was associated with cirrhosis [23/24 (95.8%) for GP73(+)/COMP(+) vs. 22/30 (73.3%) for GP73(+)/COMP(−) vs. 25/37 (67.6%) for GP73(−)/COMP(+) vs. 46/197 (23.4%) for GP73(−)/COMP(−); P < 0.001]. The combination of GP73, COMP, the aspartate aminotransferase/platelets ratio index, and the Fibrosis-4 score had even higher diagnostic accuracy to detect the presence of cirrhosis [AUC (95% CI): 0.916 (0.878–0.946)] or significant liver fibrosis (METAVIR ≥ F2) [AUC (95% CI): 0.832 (0.768–0.883)] than each marker alone. Kaplan-Meier analysis showed that positivity for both GP73 and COMP was associated with higher rates of HCC development (P < 0.001) and liver-related deaths (P < 0.001) during follow-up. In conclusion, the combination of GP73 and COMP seems efficient to detect cirrhosis and predict worse outcomes and the development of HCC in patients with chronic liver diseases.

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N. Mwambia, ANN, Mark O. Okongo, and Gladys G. Njoroge. "Stability analysis of a mathematical model for awareness initiatives on registration of persons in Kenya." International Journal of Applied Mathematical Research 9, no. 1 (March 25, 2020): 21. http://dx.doi.org/10.14419/ijamr.v9i1.29658.

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In this paper, we discuss stability analysis of a mathematical model of awareness initiatives in registration of persons in Kenya. Using Ordinary Differential Equations, a mathematical model to compare the efficacy of print media, electronic media and word-of-mouth media in disseminating registration information is developed. Positivity and boundedness of solutions is established to ensure that the model is mathematically meaningful. The Basic Reproduction number R0 is derived using the Next Generation Matrix. We present both awareness free equilibrium and the maximum awareness equilibrium. Stability analysis of the model shows that Awareness free equilibrium is both locally and globally asymptotically stable when R0 < 1 hence no spread of awareness and unstable when R0 > 1 while MAE is locally asymptotically stable when R0 > 1 indicating spread of information in the population.

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Farenick, Douglas. "The operator system of Toeplitz matrices." Transactions of the American Mathematical Society, Series B 8, no. 32 (November 17, 2021): 999–1023. http://dx.doi.org/10.1090/btran/83.

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A recent paper of A. Connes and W.D. van Suijlekom [Comm. Math. Phys. 383 (2021), pp. 2021–2067] identifies the operator system of n × n n\times n Toeplitz matrices with the dual of the space of all trigonometric polynomials of degree less than n n . The present paper examines this identification in somewhat more detail by showing explicitly that the Connes–van Suijlekom isomorphism is a unital complete order isomorphism of operator systems. Applications include two special results in matrix analysis: (i) that every positive linear map of the n × n n\times n complex matrices is completely positive when restricted to the operator subsystem of Toeplitz matrices and (ii) that every linear unital isometry of the n × n n\times n Toeplitz matrices into the algebra of all n × n n\times n complex matrices is a unitary similarity transformation. An operator systems approach to Toeplitz matrices yields new insights into the positivity of block Toeplitz matrices, which are viewed herein as elements of tensor product spaces of an arbitrary operator system with the operator system of n × n n\times n complex Toeplitz matrices. In particular, it is shown that min and max positivity are distinct if the blocks themselves are Toeplitz matrices, and that the maximally entangled Toeplitz matrix ξ n \xi _n generates an extremal ray in the cone of all continuous n × n n\times n Toeplitz-matrix valued functions f f on the unit circle S 1 S^1 whose Fourier coefficients f ^ ( k ) \hat f(k) vanish for | k | ≥ n |k|\geq n . Lastly, it is noted that all positive Toeplitz matrices over nuclear C ∗ ^* -algebras are approximately separable.

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Ahmed, Nauman, Jorge E. Macías-Díaz, Ali Raza, Dumitru Baleanu, Muhammad Rafiq, Zafar Iqbal, and Muhammad Ozair Ahmad. "Design, Analysis and Comparison of a Nonstandard Computational Method for the Solution of a General Stochastic Fractional Epidemic Model." Axioms 11, no. 1 (December 24, 2021): 10. http://dx.doi.org/10.3390/axioms11010010.

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Malaria is a deadly human disease that is still a major cause of casualties worldwide. In this work, we consider the fractional-order system of malaria pestilence. Further, the essential traits of the model are investigated carefully. To this end, the stability of the model at equilibrium points is investigated by applying the Jacobian matrix technique. The contribution of the basic reproduction number, R0, in the infection dynamics and stability analysis is elucidated. The results indicate that the given system is locally asymptotically stable at the disease-free steady-state solution when R0<1. A similar result is obtained for the endemic equilibrium when R0>1. The underlying system shows global stability at both steady states. The fractional-order system is converted into a stochastic model. For a more realistic study of the disease dynamics, the non-parametric perturbation version of the stochastic epidemic model is developed and studied numerically. The general stochastic fractional Euler method, Runge–Kutta method, and a proposed numerical method are applied to solve the model. The standard techniques fail to preserve the positivity property of the continuous system. Meanwhile, the proposed stochastic fractional nonstandard finite-difference method preserves the positivity. For the boundedness of the nonstandard finite-difference scheme, a result is established. All the analytical results are verified by numerical simulations. A comparison of the numerical techniques is carried out graphically. The conclusions of the study are discussed as a closing note.

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Desando, Giovanna, Isabella Bartolotti, Francesca Vannini, Carola Cavallo, Francesco Castagnini, Roberto Buda, Sandro Giannini, Massimiliano Mosca, Erminia Mariani, and Brunella Grigolo. "Repair Potential of Matrix-Induced Bone Marrow Aspirate Concentrate and Matrix-Induced Autologous Chondrocyte Implantation for Talar Osteochondral Repair." CARTILAGE 8, no. 1 (July 8, 2016): 50–60. http://dx.doi.org/10.1177/1947603516642573.

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Objective The low regenerative potential of cartilage contributed to the development of different cell therapies aimed to improve the clinical outcome in young patients with Osteochondral Lesions of the Talus (OLT). This study is designed to assess the regenerative potential of autologous matrix-induced Bone Marrow Aspirate Concentrate (mBMAC) and matrix-induced Autologous Chondrocyte Implantation (mACI) evaluating, on a small number of osteochondral biopsies, the expression of some catabolic, inflammatory, and pain mediators. Design Twenty-two patients with OLT were analyzed in this study; 7 were treated with mACI and 15 with mBMAC. Informed consent was obtained from all the patients. Clinical assessments were performed pre-operatively and at 12, 24, and 36 months after surgery using the American Orthopedic Foot and Ankle Society (AOFAS). Histology and immunohistochemistry were used to assess cartilage repair at 24 months. Data were analyzed using non-parametric Wilcoxon-Mann-Whitney and Spearman tests. Results A remarkable improvement in AOFAS score was noticed for both treatments up to 36 months; however, patients treated with mACI reported the best AOFAS score. Various degrees of tissue remodeling were observed by histological analysis for both cell strategies. However, mBMAC treatment showed a higher expression of some fibrous and hypertrophic markers compared to mACI group. A mild positivity for nerve growth factor, as pain mediator, was noticed for both treatments.M Conclusions Our findings demonstrated the best histological and clinical results following mACI treatment since different fibrotic and hypertrophic features were evident in the mBMAC group at 24-month follow-up.

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Fletcher, Alyson K., and Sundeep Rangan. "Iterative reconstruction of rank-one matrices in noise." Information and Inference: A Journal of the IMA 7, no. 3 (January 2, 2018): 531–62. http://dx.doi.org/10.1093/imaiai/iax014.

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Abstract We consider the problem of estimating a rank-one matrix in Gaussian noise under a probabilistic model for the left and right factors of the matrix. The probabilistic model can impose constraints on the factors including sparsity and positivity that arise commonly in learning problems. We propose a family of algorithms that reduce the problem to a sequence of scalar estimation computations. These algorithms are similar to approximate message-passing techniques based on Gaussian approximations of loopy belief propagation that have been used recently in compressed sensing. Leveraging analysis methods by Bayati and Montanari, we show that the asymptotic behavior of the algorithm is described by a simple scalar equivalent model, where the distribution of the estimates at each iteration is identical to certain scalar estimates of the variables in Gaussian noise. Moreover, the effective Gaussian noise level is described by a set of state evolution equations. The proposed approach to deriving algorithms thus provides a computationally simple and general method for rank-one estimation problems with a precise analysis in certain high-dimensional settings.

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Abd ElRaouf, Hazem M., Alhaytham M. Aref, Ahmed K. Elsherif, and Mohamed E. Khalifa. "Study and Analysis of Corona-Virus Transfer Dynamics using Enhanced SEIR Epidemic Model with Vaccination Effect." Journal of Physics: Conference Series 2304, no. 1 (August 1, 2022): 012002. http://dx.doi.org/10.1088/1742-6596/2304/1/012002.

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Abstract Corona Virus Syndrome (COVID-19) is a contagious disease and it is considered one of the deadliest viruses ever known to humanity. In this work, the transmission dynamics of the COVID- 19 has been studied using an enhanced SEIR epidemic compartmental model with a vaccination compartment. This model divides the whole population into five categories: susceptible (S), exposed (E), infectious (I), recovered (R), and vaccinated (V). Firstly, Positivity, Existence and Uniqueness of solution are illustrated. Secondly, a mathematical analysis is done to study the equilibrium points of the model and the basic reproduction number has been computed using Next Generation Matrix method. Thirdly, by using analytical computation the Stability of disease free equilibrium (DFE) point of the model is discussed and the Existence, and uniqueness of the endemic equilibrium are proved. Finally, Bifurcation coefficient is computed using the available data and Simulations are made to illustrate the effect of the transmission rate and vaccination rate on the value of the basic reproduction number.

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Li, Zhexuan, Changhan Chen, Juncheng Wang, Ming Wei, Guancheng Liu, Yuexiang Qin, Li She, et al. "Overexpressed PLAU and its potential prognostic value in head and neck squamous cell carcinoma." PeerJ 9 (January 15, 2021): e10746. http://dx.doi.org/10.7717/peerj.10746.

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Background Metastasis is a major event for survival and prognosis in patients with head and neck squamous cell carcinomas (HNSCC). A primary cause of metastasis is the proteolytic degradation of the extracellular matrix (ECM). The plasminogen activator urokinase (PLAU) is involved in the transformation of plasminogen to plasmin leading to hydrolyzation of ECM-related proteins. However, the role of PLAU expression in HNSCC is unclear and the worth being investigated. Methods PLAU expression profiles and clinical parameters from multiple HNSCC datasets were used to investigate the relationship of PLAU expression and HNSCC survival. GO and PPI network were established on PLAU-related downstream molecular. The stroma score was deconvoluted for analysis of PLAU’s association with the immune environment. ROC analysis was applied to show the performance of PLAU in predicting HNSCC prognosis. Results PLAU mRNA was significantly elevated, as opposed to its methylation, in HNSCC tumor samples over normal specimens (all p < 0.01). Univariate and multivariate cox analysis showed PLAU could be an independent indicator for HNSCC prognosis. Combining with neck lymph node status, the AUC of PLAU in predicting 5-years overall survival reached to 0.862. GO enrichment analysis showed the major biological process (extracellular matrix organization and the P13K-Akt signaling pathway) may involve to the possible mechanism of PLAU’s function on HNSCC prognosis. Furthermore, PLAU expression was positively correlated with stroma cell score, M1 type macrophages, and negatively associated with CD4 + T cell, Tregs cell, and follicular helper T cell. Conclusions PLAU might be an independent biomarker for predicting outcomes of HNSCC patients. The elevated expression of PLAU was associated with HPV positivity and neck node status. The PI3K-Akt pathway and aberrant proportions of immune cells might underly the mechanism of PLAU’s oncogene role in HNSCC.

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Vanier, Antoine, Josef S. Smolen, Cornelia F. Allaart, Ronald Van Vollenhoven, Patrick Verschueren, Nathan Vastesaeger, Saedis Saevarsdottir, et al. "An updated matrix to predict rapid radiographic progression of early rheumatoid arthritis patients: pooled analyses from several databases." Rheumatology 59, no. 8 (November 13, 2019): 1842–52. http://dx.doi.org/10.1093/rheumatology/kez542.

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Abstract Objective In early RA, some patients exhibit rapid radiographic progression (RRP) after one year, associated with poor functional prognosis. Matrices predicting this risk have been proposed, lacking precision or inadequately calibrated. We developed a matrix to predict RRP with high precision and adequate calibration. Methods Post-hoc analysis by pooling individual data from cohorts (ESPOIR and Leuven cohorts) and clinical trials (ASPIRE, BeSt and SWEFOT trials). Adult DMARD-naïve patients with active early RA for which the first therapeutic strategy after inclusion was to prescribe methotrexate or leflunomide were included. A logistic regression model to predict RRP was built. The best model was selected by 10-fold stratified cross-validation by maximizing the Area Under the Curve. Calibration and discriminatory power of the model were checked. The probabilities of RRP for each combination of levels of baseline characteristics were estimated. Results 1306 patients were pooled. 20.6% exhibited RRP. Four predictors were retained: rheumatoid factor positivity, presence of at least one RA erosion on X-rays, CRP > 30mg/l, number of swollen joints. The matrix estimates RRP probability for 36 combinations of level of baseline characteristics with a greatly enhanced precision compared with previously published matrices (95% CI: from ± 0.02 minimum to ± 0.08 maximum) and model calibration is excellent (P = 0.79). Conclusion A matrix proposing RRP probability with high precision and excellent calibration in early RA was built. Although the matrix has moderate sensitivity and specificity, it is easily usable and may help physicians and patients to make treatment decisions in daily clinical practice.

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Ramayah, T., Lo May Chiun, Kamel Rouibah, and Oh Sook May. "Identifying Priority Using an Importance-Performance Matrix Analysis (IPMA)." International Journal of E-Adoption 6, no. 1 (January 2014): 1–15. http://dx.doi.org/10.4018/ijea.2014010101.

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This study used the combined Technology Acceptance Model (TAM) and Theory of Planned Behavior (TPB) as the theoretical underpinning to examine the adoption of Internet banking. Five factors (perceived ease of use, perceived usefulness, attitude, subjective norms, and perceived behavioral control) were identified to model their impact on intention to adopt Internet banking individual bank customers in Malaysia. Survey questions from prior studies were adopted and customized to collect data. A total of 239 customers responded to the survey. Partial least Square (PLS) SmartPLS M2 Version 2.0 was used for data analysis. Perceived ease of use significantly influenced perceived usefulness but did not impact attitude. Perceived usefulness was positively related to attitude and also intention to use. Attitude and subjective norm were significant predictors of intention to use while perceived behavioral control was not significant. Further to that we conducted an Importance-Performance matrix analysis to determine priority variables to focus on for the implications to practitioners.

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Shrestha, A., and S. Carnelio. "Evaluation of Matrix Metalloproteinases-2 (MMP-2) and Tissue Inhibitors of Metalloproteinases-2 (TIMP-2) in Oral Submucous Fibrosis and Their Correlation With Disease Severity." Kathmandu University Medical Journal 11, no. 4 (September 23, 2015): 274–81. http://dx.doi.org/10.3126/kumj.v11i4.12521.

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Background Oral submucous fibrosis (OSF), a potentially malignant oral lesion, is a form of pathological fibrosis affecting the oral mucosa. It results from an imbalance in equilibrium of the normal process of synthesis and degradation of extra cellular matrix. Matrix metalloproteinases and its inhibitors play important role in remodeling of the extra cellular matrix which are important in progression and pathogenesis of potentially malignant lesions to malignancy.Objectives To evaluate the expression and distribution of Matrix metalloproteinases-2 (MMP- 2) and Tissue inhibitor of metalloproteinases-2 (TIMP-2) in different grades of Oral Submucous Fibrosis(OSF).Method Immunohistochemical analysis for MMP-2 and its TIMP-2 was performed in 30 histopathologically confirmed, formalin fixed, paraffin embedded specimens of OSF. A semi-quantitative analysis was done to assess the expression, distribution and comparison of these in various stages of this disease.Result All moderately advanced cases and 64.2% for MMP-2 and 78.5% for TIMP-2 of early stage cases showed positivity. Between two stages of OSF, statistically significant differences were noted in expression of TIMP-2 in lamina propria, deep connective tissue and supra basal layers (p<0.05) and basal and supra basal layers for MMP-2 (p<0.05).Conclusion The simultaneous increase in expression of MMP-2 and TIMP-2 with advancing stages of OSF can provide a basis for considering the proteases as important mediators in the pathogenesis and progression of OSF which could aid in identifying the aggressiveness of the condition and elucidate its role in its malignant transformation.Kathmandu Univ Med J 2013; 11(4): 274-281

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Ren, Yingying, and Qian Wang. "Frequency-Limited Model Reduction for Linear Positive Systems: A Successive Optimization Method." Applied Sciences 13, no. 6 (March 22, 2023): 4039. http://dx.doi.org/10.3390/app13064039.

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This paper studies frequency-limited model reduction for linear positive systems. Specifically, the objective is to develop a reduced-order model for a high-order positive system that preserves the positivity, while minimizing the approximation error within a given H∞ upper bound over a limited frequency interval. To characterize the finite-frequency H∞ specification and stability, we first present the analysis conditions in the form of bilinear matrix inequalities. By leveraging these conditions, we derive convex surrogate constraints by means of an inner-approximation strategy. Based on this, we construct a novel iterative algorithm for calculating and optimizing the reduced-order model. Finally, the effectiveness of the proposed model reduction method is illustrated with a numerical example.

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Saesue, Prajak, Ekawut Chankaew, Orasa Chawalparit, Nollaporn Sudasna Na Ayudhya, Sorranart Muangsomboon, and Tumtip Sangruchi. "Primary extraskeletal osteosarcoma in the pineal region." Journal of Neurosurgery 101, no. 6 (December 2004): 1061–64. http://dx.doi.org/10.3171/jns.2004.101.6.1061.

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✓ Primary extraskeletal osteosarcoma occurring in the brain parenchyma is distinctly uncommon, with only five cases having been reported. The authors describe the case of a 45-year-old man who presented with progressive headache and diplopia. Computerized tomography scanning and magnetic resonance imaging results revealed a pineal region tumor with obstructive hydrocephalus. The patient underwent partial resection of the tumor. The histological examination showed large pleomorphic tumor cells embedded in osteoid matrix. Immunohistochemical analysis was negative for various antibodies and thus excluded a glial, germ cell, epithelial, and lymphoid tumor origin. Only vimentin showed strong positivity in most of the tumor cells. Ultrastructurally, the tumor cells were rich in dilated rough endoplasmic reticula. Clear zones between tumor cells and osteoid matrix were observed. The osteoid matrix was made up of small collagen fibrils and hydroxyapatite deposits. The tumor was not attached to the bone structure of the skull. These findings are consistent with the features of extraskeletal osteosarcoma. Data from complete medical and radiological studies excluded a metastatic origin for this tumor. Partial resection and postoperative radiotherapy had provided tumor control at 11 months after the onset of symptoms. This is the first reported case of a primary extraskeletal osteosarcoma occurring in the pineal region.

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Rauthmann, John F., and Ryne A. Sherman. "Ultra-Brief Measures for the Situational Eight DIAMONDS Domains." European Journal of Psychological Assessment 32, no. 2 (April 2016): 165–74. http://dx.doi.org/10.1027/1015-5759/a000245.

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Abstract. People perceive psychological situations on the “Situational Eight” DIAMONDS characteristics (Duty, Intellect, Adversity, Mating, pOsitivity, Negativity, Deception, Sociality; Rauthmann et al., 2014 ). To facilitate situational assessment and economically measure these dimensions, we propose four ultra-brief one-item scales (S8-I, S8-II, S8-III-A, S8-III-P) validated against the already existing 24-item S8*. Convergent/discriminant validity of the four S8-scales was examined by analyses of the multi-characteristics multi-measures matrix, and their nomological associations with external criteria were compared. Application areas of the scales are discussed.

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Scendoni, Roberto, Emanuele Bury, Erika Buratti, Rino Froldi, Marta Cippitelli, Gianmario Mietti, and Mariano Cingolani. "Detection of Morphine and Opioids in Fingernails: Immunohistochemical Analysis and Confirmation with Ultra-High-Performance Liquid Chromatography Coupled with High-Resolution Mass Spectrometry." Toxics 10, no. 8 (July 26, 2022): 420. http://dx.doi.org/10.3390/toxics10080420.

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This study aimed to investigate the detection of morphine in fingernails from forensic autopsies using immunohistochemistry (IHC), with confirmation by ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS). A primary antibody specific to morphine and a secondary antibody conjugated to horseradish peroxidase (HRP) was used. IHC on specimens of Subjects A and B (both drug addicts) resulted in the detection of morphine on a cell layer of the nail plate matrix. UHPLC-HRMS and GC-MS analysis showed that Subject A had a morphine concentration of 0.35 ng/mg in the fingernail and 472 ng/mL in the blood, while Subject B reached 1.23 ng/mg in the fingernail and 360 ng/ml in the blood. Most of those matrices were positive for codeine, methadone, EDDP, and 6-MAM. The use of IHC in Subject C (a former addict) showed no positivity for morphine in the fingernail, while the UHPLC-HRMS analysis confirmed its absence in the fingernail and blood. Additionally, an analysis of the scalp or pubic hair of the subjects was carried out using UHPLC-HRMS. The results suggest that IHC can be used to establish the site of accumulation of morphine in the nail matrix; for postmortem diagnosis; and that basic substances can be detected by UHPLC-HRMS. There are no previous studies on the use of IHC as a technique for forensic purposes in unconventional matrices, such as nails.

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Tsetimi, Jonathan, Marcus Ifeanyi Ossaiugbo, and Augustine Atonuje. "Bifurcation Analysis of a Mathematical Model for the Covid-19 Infection among Pregnant and Non-Pregnant Women." European Journal of Pure and Applied Mathematics 15, no. 2 (April 30, 2022): 537–56. http://dx.doi.org/10.29020/nybg.ejpam.v15i2.4312.

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A mathematical study and analysis of the covid-19 disease is essential in the control and eradication of the dreadful covid-19 infection. This research work is focused on the covid-19 infection among the women population. The women population was divided into seven compartments. These compartments were built into a deterministic model presented as a system of ordinary differential equations. Basic mathematical analyses such as positivity of solution, the disease-free equilibrium and the basic reproduction number, were performed on the model. The model assumes only positive solutions and the total population size is bounded. The next generation matrix approach was employed in generating the basic reproduction number R0. The sensitivity analysis revealed that among the most sensitive parameters of R0 are the effective contact rate for Covid-19 transmission, the modification parameter accounting for increased susceptibility to covid-19 infection by pregnant women, and the transmission coefficient of the infectious pregnant women. The bifurcation analysis revealed a forward bifurcation which guarantees the stability of the disease-freeequilibrium when R0 is lowered below unity. Numerical simulations, using Mathematica Version 12.0 package, are given to show the effects of the most sensitive parameters of the basic reproduction number on the number of infectious cases of covid-19.

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Plata-Hipólito, Claudia B., Sibilina Cedillo-Rosales, Nelson Obregón-Macías, Carlos E. Hernández-Luna, Cristina Rodríguez-Padilla, Reyes S. Tamez-Guerra, and Juan F. Contreras-Cordero. "Genetic and serologic surveillance of canine (CIV) and equine (EIV) influenza virus in Nuevo León State, México." PeerJ 7 (December 17, 2019): e8239. http://dx.doi.org/10.7717/peerj.8239.

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Background Despite the uncontrolled distribution of the Influenza A virus through wild birds, the detection of canine influenza virus and equine influenza virus in Mexico was absent until now. Recently, outbreaks of equine and canine influenza have been reported around the world; the virus spreads quickly among animals and there is potential for zoonotic transmission. Methods Amplification of the Influenza A virus matrix gene from necropsies, nasal and conjunctival swabs from trash service horses and pets/stray dogs was performed through RT-PCR. The seroprevalence was carried out through Sandwich enzyme-linked immunosorbent assay system using the M1 recombinant protein and polyclonal antibodies anti-M1. Results The matrix gene was amplified from 13 (19.11%) nasal swabs, two (2.94%) conjunctival swabs and five (7.35%) lung necropsies, giving a total of 20 (29.41%) positive samples in a pet dog population. A total of six (75%) positive samples of equine nasal swab were amplified. Sequence analysis showed 96–99% identity with sequences of Influenza A virus matrix gene present in H1N1, H1N2 and H3N2 subtypes. The phylogenetic analysis of the sequences revealed higher identity with matrix gene sequences detected from zoonotic isolates of subtype H1N1/2009. The detection of anti-M1 antibodies in stray dogs showed a prevalence of 123 (100%) of the sampled population, whereas in horses, 114 (92.68%) positivity was obtained. Conclusion The results unveil the prevalence of Influenza A virus in the population of horses and dogs in the state of Nuevo Leon, which could indicate a possible outbreak of equine and Canine Influenza in Mexico. We suggest that the prevalence of Influenza virus in companion animals be monitored to investigate its epizootic and zoonotic potential, in addition to encouraging the regulation of vaccination in these animal species in order to improve their quality of life.

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Díaz-Rodríguez, Iván D., Gerardo Romero, and Cesar Elizondo. "New Algorithm Based on Sign Decomposition to Verify the Robust Stability Property for a Class of Linear Time-Delay Systems." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/217904.

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The main focus of this paper is to analyze the robust stability property for a class of time-delay systems when parametric polynomic uncertainty is considered. The analysis is made by replacing the time-delay part with an auxiliary equation and then using the sign definite decomposition to deal with the polynomic parametric uncertainty. Also, it is shown that it is possible to verify the robust stability property by first obtaining the Hurwitz matrix from the characteristic equation for this class of systems and then checking the leading principal minors positivity using the sign definite decomposition. Finally, an algorithm codified in MATLAB is used to evaluate and graphically show the robust stability property. This is shown by a series of points that were calculated using the sign definite decomposition.

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Khan, Ihsan Ullah, Amjid Hussain, Shuo Li, and Ali Shokri. "Modeling the Transmission Dynamics of Coronavirus Using Nonstandard Finite Difference Scheme." Fractal and Fractional 7, no. 6 (May 31, 2023): 451. http://dx.doi.org/10.3390/fractalfract7060451.

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A nonlinear mathematical model of COVID-19 containing asymptomatic as well as symptomatic classes of infected individuals is considered and examined in the current paper. The largest eigenvalue of the next-generation matrix known as the reproductive number is obtained for the model, and serves as an epidemic indicator. To better understand the dynamic behavior of the continuous model, the unconditionally stable nonstandard finite difference (NSFD) scheme is constructed. The aim of developing the NSFD scheme for differential equations is its dynamic reliability, which means discretizing the continuous model that retains important dynamic properties such as positivity of solutions and its convergence to equilibria of the continuous model for all finite step sizes. The Schur–Cohn criterion is used to address the local stability of disease-free and endemic equilibria for the NSFD scheme; however, global stability is determined by using Lyapunov function theory. We perform numerical simulations using various values of some key parameters to see more characteristics of the state variables and to support our theoretical findings. The numerical simulations confirm that the discrete NSFD scheme maintains all the dynamic features of the continuous model.

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Kiyasu, Yoshiyuki, Ken Hayashi, Go Miyahara, and Makoto Narita. "Solitary Pancreatic Metastasis From Breast Matrix-Producing Carcinoma: A First Case Report." International Surgery 102, no. 7-8 (August 1, 2017): 294–98. http://dx.doi.org/10.9738/intsurg-d-17-00064.1.

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Introduction: Breast matrix-producing carcinoma (MPC) is a rare histologic type. Pancreatic metastases from breast cancers are also rare. We report the first case of solitary pancreatic metastasis from breast MPC, treated with distal pancreatectomy. Case presentation: A 56-year-old woman presented with a 56-mm mass in her right breast and a swollen right axillary lymph node. Both lesions had characteristic early ring enhancement on dynamic magnetic resonance imaging (MRI). Tumor biopsy revealed MPC. She underwent total mastectomy and axillary clearance. On histopathologic examination, the tumor was composed of extracellular matrix with areas of osseous and chondroid differentiation without spindle cells or osteoclasts, surrounded by a dense population of glandular epithelial tumor cells. On immunohistochemical analysis, the tumor cells were positive for AE1/AE3 and cytokeratin 5/6. The final diagnosis was breast MPC with axillary metastasis. Two years later, dynamic MRI displayed a mass in the pancreatic body with early ring enhancement, suspicious for solitary breast MPC metastasis. Distal pancreatectomy was performed. Histopathologic examination revealed bone and cartilaginous matrix with necrosis, surrounded by pleomorphic sarcomatous tumor cells. Tumor cells showed less cytokeratin positivity than the primary breast lesion. These findings were compatible with breast MPC metastasis. Conclusion: Solitary pancreatic metastasis from breast MPC has not yet been reported. Surgical resection of malignant pancreatic metastases is controversial; however, considering that breast MPC has limited responsiveness to radiotherapy and chemotherapy, curative resection would be important in this case. The histopathologic features of MPC may reflect enhancement and calcification on radiologic studies.

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Reverter-Branchat, Gemma, Jaume Bosch, Jessica Vall, Magí Farré, Esther Papaseit, Simona Pichini, and Jordi Segura. "Determination of Recent Growth Hormone Abuse Using a Single Dried Blood Spot." Clinical Chemistry 62, no. 10 (October 1, 2016): 1353–60. http://dx.doi.org/10.1373/clinchem.2016.257592.

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Abstract BACKGROUND Although it is being increasingly applied, blood collection for drug testing in sport presents some logistic issues that complicate full applicability on a large scale. The use of dried blood spots (DBS) could benefit compliant blood testing considerably owing to its simplicity, minimal invasiveness, analyte stability, and reduced costs. The aim of this study was to evaluate the applicability of DBS to the methodology approved by the World Anti-Doping Agency (WADA) for detection of doping by recombinant human growth hormone (rhGH) in serum. METHODS A protocol for a single DBS analysis using the hGH isoforms differential immunoassays (kit 1 and kit 2) was developed and validated. A clinical study with healthy volunteers injected for 3 consecutive days with a low subcutaneous dose (0.027 mg · kg−1 · day−1 · person−1) of rhGH was conducted. Finger prick DBS and paired-time serum samples from arm venipuncture were compared. RESULTS The analysis of the DBS-based protocol indicated that with only a single blood spot it was possible to detect positivity for growth hormone abuse. In spite of the low rhGH dose administered and independently of the kit used, the window of detection for DBS was confirmed in all analyzed samples up to 8 h after rhGH administration and extended up to 12 h in 50% of the cases. Serum positivity was detected in all studied samples for 12 h after administration. CONCLUSIONS These results support the usefulness of DBS as a biological matrix for testing recent growth hormone abuse.

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Al-Maqrashi, Kifah, Fatma Al-Musalhi, Ibrahim ELmojtaba, and Nasser Al-Salti. "Investigating the Role of Mobility between Rural Areas and Forests on the Spread of Zika." BIOMATH 11, no. 2 (December 22, 2022): 2212149. http://dx.doi.org/10.55630/j.biomath.2022.12.149.

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A mathematical model of Zika virus transmission, incorporating human movement between rural areas and nearby forests, is presented to investigate the role of human movement in the spread of Zika virus infections in human and mosquito populations. Proportions of both susceptible and infected humans living in rural areas are assumed to move to nearby forest areas. Direct, indirect, and vertical transmission routes are incorporated for all populations. A mathematical analysis of the proposed model is presented. The analysis starts with normalizing the proposed model. The positivity and boundedness of solutions to the normalized model are then addressed. The basic reproduction number is calculated using the next-generation matrix method and its relation to the three routes of disease transmission has been presented. The sensitivity analysis of the basic reproduction number to all model parameters is investigated. The analysis also includes the existence and stability of disease-free and endemic equilibrium points. Bifurcation analysis is also carried out. Finally, numerical solutions to the normalized model are obtained to confirm the theoretical results and demonstrate human movement's role in disease transmission in human and mosquito populations.

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Verbicaro, Thalyta, Allan Fernando Giovanini, Joao Cesar Zielak, Flares Baratto Filho, Melissa Rodrigues de Araujo, and Tatiana Miranda Deliberador. "Osteocalcin Immunohistochemical Expression During Repair of Critical-Sized Bone Defects Treated with Subcutaneous Adipose Tissue in Rat and Rabbit Animal Model." Brazilian Dental Journal 24, no. 6 (December 2013): 559–64. http://dx.doi.org/10.1590/0103-6440201302362.

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The aim of this study was to evaluate the osteocalcin immunoexpression during the bone repair treated with subcutaneous adipose tissue in rats and rabbits. Fourteen rats and 14 rabbits were used in the study. A critical-sized calvarial defect was created in each animal. The animals were divided into 4 experimental groups: RC (rat control), RbC (rabbit control), RAT (rat adipose tissue), RbAT (rabbit adipose tissue). In the groups RC and RbC the defect was filled with a blood clot. In groups RAT and RbAT, the defect was filled with macerated subcutaneous adipose tissue. The euthanasia was performed at 30 days (RC and RAT) and 40 days (RbC and RbAT). Histological analysis and immunohistochemical analysis of osteocalcin protein expression were performed. Data were submitted to descriptive statistical analysis (mode). Osteocalcin immunoexpression was detected in the experimental models. Notwithstanding, RbAT showed higher positivity, especially in the adipocytes, than the group RAT group. In groups RC and RbC, the surgical wound was filled by collagen fibers. In Group RAT, the defect was composed by collagen fibers and adipocytes in the reparative sites. Similarly, in RbAT, the defect also was partially filled by collagen fibers and presence of adipocytes dispersed among the fibers. Additionally, chronic inflammatory process and areas of bone matrix deposition were observed. It may be concluded that in both animal models the adipose tissue demonstrated low osteogenic capacity. However, the rabbit animal model exhibited a more evident osteocalcin immunoexpression and a greater amount of newly formed bone matrix.

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Rutka, James T., Craig A. Myatt, Jane R. Giblin, Richard L. Davis, and Mark L. Rosenblum. "Distribution of Extracellular Matrix Proteins in Primary Human Brain Tumours: An Immunohistochemical Analysis." Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques 14, no. 1 (February 1987): 25–30. http://dx.doi.org/10.1017/s0317167100026123.

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Abstract:Using immunohistochemical techniques, we localized several glycoproteins of the extracellular matrix in paraffin-embedded sections of 4 normal brain and 38 primary intracranial tumour specimens. All specimens were positively immunostained to various degrees by monoclonal antibodies to type IV collagen and procollagen III and by antisera to laminin and fibronectin. Staining was consistently most intense at sites of contact between neuroepithelial and mesenchymal or leptomeningeal elements; there was no demonstrable staining within or between neuroepithelial elements in the neuropil. Tumour cells from meningiomas and from the sarcomatous portion of a gliosarcoma were positively immunostained for fibronectin and laminin. The integrity of the glial limitans externa was demonstrated by the positive linear reaction product produced by immunostains for type IV collagen and laminin, even in the most malignant gliomas. The deposition of extracellular matrix glycoproteins at the glial-mesenchymal interface observed in this study of primary human brain tumours is a manifestation of one of the interactions between tumour and stromal cells in the central nervous system. A loss of coordination and an alteration in the interactions between epithelial cells and stromal cells across extracellular matrices such as basement membranes are thought to be fundamental steps in the development and progression of cancer. Further characterization studies focusing on other markers of the extracellular matrix are needed to elucidate completely the function of this structure in the central nervous system.

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Zhou, Xueyong, and Xiangyun Shi. "Stability analysis and backward bifurcation on an SEIQR epidemic model with nonlinear innate immunity." Electronic Research Archive 30, no. 9 (2022): 3481–508. http://dx.doi.org/10.3934/era.2022178.

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<abstract><p>Infectious diseases have a great impact on the economy and society. Dynamic models of infectious diseases are an effective tool for revealing the laws of disease transmission. Quarantine and nonlinear innate immunity are the crucial factors in the control of infectious diseases. Currently, there no mathematical models that comprehensively study the effect of both innate immunity and quarantine. In this paper, we propose and analyze an SEIQR epidemic model with nonlinear innate immunity. The boundedness and positivity of the solutions are discussed. Employing the next-generation matrix, we compute the expression of the basic reproduction number. Under certain conditions, the phenomenon of backward bifurcation may occur. That is to say, the stable disease-free equilibrium point and the stable endemic equilibrium point coexist when the basic reproduction ratio is less than one. And the basic reproduction number is no longer the threshold value to determine whether the disease breaks out. We investigate the globally asymptotical stability of the disease-free equilibrium point for the system by constructing Lyapunov function. Also, we research the global stability of the endemic equilibrium by using geometric approach. Numerical simulations are carried out to reveal the theoretical results and find some complex dynamics (for example, the existence of Hopf bifurcation) of the system. Both theoretical and numerical results indicate that the nonlinear innate immunity may cause backward bifurcation and Hopf bifurcation, which makes more difficult to eliminate the disease.</p></abstract>

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Gao, Peng Bin, Wei Wei Wu, and Bo Yu. "Analysis of NPD Performance Based on a Meta-Analysis and Structural Equations Modeling Examination." Advanced Materials Research 774-776 (September 2013): 2017–20. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.2017.

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The structure dimensions and the interactions of new product development performance have stimulated debate lasting many years. To synthesize accumulating research findings, meta-analytic structural equation modeling was employed. Product advantage, time efficiency, cost efficiency and product success were used to measure the performance based on past literature. The correlation matrix of four performance variables was included in the meta-analysis based on 44 studies. The results of structural equations modeling show that the one-factor model is proposed as best-fitting alternative model of NPD performance, and the internal performance including product advantage, time and cost efficiency variables are positively associated with external performance.

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José Natário, Alexandre, Glaucia Luciano da Veiga, Vagner Loduca Lima, Thaís Gascón, José Claudio dos Santos Pinheiro, Joyce Regina Santos Raimundo, Beatriz Da Costa Aguiar Alves, et al. "The influence of social isolation on the incidence of positivity in covid-19 tests in a metropolitan region of São Paulo, Brazil." Journal of Human Growth and Development 31, no. 3 (December 1, 2021): 476–83. http://dx.doi.org/10.36311/jhgd.v31.12656.

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Introduction: With the arrival of the SARS-CoV-2 (Coronavirus 2 of severe acute respiratory syndrome) pandemic in Brazil, especially in the city of São Paulo, there was a need to apply social isolation policies associated with testing, covering all municipalities. The Clinical Analysis Laboratory of Centro Universitário FMABC was one of the first laboratories to receive certification and qualification to perform RT-PCR (reverse transcriptase reaction followed by polymerase chain reaction) tests in the metropolitan region of São Paulo. Objective: Aim to analyze the influence of adopting social isolation on the incidence of positivity in COVID-19 tests in the metropolitan region of São Paulo, Brazil. Methods: a descriptive study carried out from March to May 2020, epidemiological data were collected from each unit served and organized by the data controllership team of the Clinical Analysis Laboratory of FMABC. Epidemiological, demographic, and laboratory data were extracted from the Matrix® outpatient data management system. Clinically suspected cases and confirmed by laboratory tests (RT-PCR and serological tests) were entered. The tests were divided into serological tests using the RT-PCR molecular test, on samples of nasopharyngeal mucosal scrapings collected with sterile Swab. Results: It were evaluated PCR test and antibody presence (IgA, IgM and IgG) in blood samples of 16.297 patients. 22.718 tests were performed for the diagnosis of COVID-19, both RT-PCR (10.410 tests) and serological tests to detect anti-SARS-CoV-2 antibodies, IgA, IgM and IgG, a total of 16.297 patients were assessed, 63% women and 37% men. It was observed that the social isolation policies adopted during this period contained the massive expansion of contamination, at least while the social isolation rates were above 55%. Conclusion: The data of this study demonstrated the effectiveness of social isolation in containing the positive contamination of SARS-CoV-2 in the metropolitan region of São Paulo, at least for the first three months.

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Pierre-Jean, Morgane, Florence Mauger, Jean-François Deleuze, and Edith Le Floch. "PIntMF: Penalized Integrative Matrix Factorization method for multi-omics data." Bioinformatics 38, no. 4 (November 26, 2021): 900–907. http://dx.doi.org/10.1093/bioinformatics/btab786.

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Abstract Motivation It is more and more common to perform multi-omics analyses to explore the genome at diverse levels and not only at a single level. Through integrative statistical methods, multi-omics data have the power to reveal new biological processes, potential biomarkers and subgroups in a cohort. Matrix factorization (MF) is an unsupervised statistical method that allows a clustering of individuals, but also reveals relevant omics variables from the various blocks. Results Here, we present PIntMF (Penalized Integrative Matrix Factorization), an MF model with sparsity, positivity and equality constraints. To induce sparsity in the model, we used a classical Lasso penalization on variable and individual matrices. For the matrix of samples, sparsity helps in the clustering, while normalization (matching an equality constraint) of inferred coefficients is added to improve interpretation. Moreover, we added an automatic tuning of the sparsity parameters using the famous glmnet package. We also proposed three criteria to help the user to choose the number of latent variables. PIntMF was compared with other state-of-the-art integrative methods including feature selection techniques in both synthetic and real data. PIntMF succeeds in finding relevant clusters as well as variables in two types of simulated data (correlated and uncorrelated). Next, PIntMF was applied to two real datasets (Diet and cancer), and it revealed interpretable clusters linked to available clinical data. Our method outperforms the existing ones on two criteria (clustering and variable selection). We show that PIntMF is an easy, fast and powerful tool to extract patterns and cluster samples from multi-omics data. Availability and implementation An R package is available at https://github.com/mpierrejean/pintmf. Supplementary information Supplementary data are available at Bioinformatics online.

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Yunus, Akeem Olarewaju, and Musibau Abayomi Omoloye. "Mathematical Analysis of Efficacy of Condom as a Contraceptive on the Transmission of Chlamydia Disease." International Journal of Computer Science and Mobile Applications 10, no. 2 (February 28, 2022): 22–37. http://dx.doi.org/10.47760/ijcsma.2022.v10i02.002.

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Chlamydia disease caused by the Chlamydia trachomatis is one of the major sexually transmitted infectious diseases globally. The progression of this disease has deadly effects cumulating into millions of death. Chlamydia causes numerous complications such as infertility in female, chronic pelvic pain and inflammation. Previous studies did not consider the effects of undetected infected individuals on the dynamic spread of the disease. Hence, this work investigated the effects of undetected infected individuals and efficacy of condom as a contraceptive in the dynamic spread of the disease. A six compartmental model to study the dynamic spread of chlamydia disease was developed using system of ordinary differential equation. The population was divided into susceptible, exposed, infected undetected symptomatic, infected detected symptomatic, infected asymptomatic and recovered individuals. The well-posedness of the model was investigated by the positivity of solution technique. Basic reproduction number (R0) was computed using Next Generation Matrix Method. The endemic equilibrium was investigated by the use of Lyapunov function. The results showed that the disease free equilibrium was stable whenever the basic reproduction number is less than unity (R0<1). The endemic equilibrium was found to be stable as a results of constructed Lyapunov function being negative definite. Numerical analysis showed that increasing in the undetected infected individuals enhanced the spread of the disease. Findings showed that undetected infected individuals played a vital role in the spread of Chlamydia disease. Moreover, using condom as a contraceptive reduced the spread of the disease.

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Knoll, T. F., L. L. Brinkley, and E. J. Delp. "Difference picture algorithms for the analysis of extracellular components of histological images." Journal of Histochemistry & Cytochemistry 33, no. 4 (April 1985): 261–67. http://dx.doi.org/10.1177/33.4.3980979.

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A computer-assisted method for objectively identifying and displaying the distribution of molecules that can only be positively identified by a combination of staining characteristics and susceptibility to specific enzymatic digestion or chemical degradation is presented. The visual image of an enzymatically digested tissue section is subtracted from that of an adjacent buffer-incubated control section and the distribution of the extracellular molecules removed from the tissue section displayed. Photomicrographs are taken using white light and narrow bandwidth filters of wavelengths at or near the maximum absorbance for the dye products used to visualize the extracellular matrix and cells. Each negative is standardized using reference gray levels. The cell and matrix images of both digested and undigested sections are then registered. The locations of cells in both control and digested sections are identified and set to an undefined gray level value in the matrix images. The cell-removed images of the control and digested sections are then registered and the difference in gray levels between the two images calculated and displayed. The validity of results obtained is primarily dependent on the soundness of the histological visualization and digestion techniques used, but is independent of investigator interpretation.

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Yanti, Teti Sofia, Anneke Iswani Ahmad, and Iwan Setiawan. "Transfer Payments and Economic Sector Performance: Input-Output Analysis in Bandung Regency." Indonesian Journal of Economics and Management 3, no. 2 (March 31, 2023): 304–12. http://dx.doi.org/10.35313/ijem.v3i2.4790.

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This study analyzes the effect of transfer funds on Bandung Regency's economic sectors in 2022, using input-output table analysis to formulate suitable allocation policies for economic development goals. The research was conducted using the Location Quotient (LQ) method. This research produced an inverse Leontif matrix. Leontif's inverse matrix can be used to analyze the interrelationships between economic sectors in Bandung Regency. Revised: The government transfer expenditure in Kabupaten Bandung in 2022 had a direct impact of IDR 459,979,360,622.89 on the Government Administration, Defense, and Mandatory Social Security sector. The indirect impact or multiplier effect on the other 16 economic sectors was IDR 241,790,256,760.42. Analysis through the Leontief inverse matrix shows that the increase of final demand in all sectors by IDR 1 billion would result in an output increase of IDR 1.53 billion in the Government Administration, Defense, and Mandatory Social Security sector. Conversely, if the final demand in that sector increases by IDR 1 billion, the output of all sectors will increase by IDR 1.02 billion. Therefore, the government transfer expenditure in Kabupaten Bandung positively impacted the growth of all economic sectors.

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Journal articles on the topic 'Matrix Analysis and Positivity'

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