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In this work, symmetry groups are used to determine symmetry reductions of a (2 + 1)‐dimensional Keller–Segel system depending on two arbitrary functions. We show that the point symmetries of the considered Keller–Segel system comprise an infinite‐dimensional Lie algebra which involves three arbitrary functions. By way of example, we have used these point symmetries to reduce straightaway the given system of second‐order partial differential equations to a system of second‐order ordinary differential equations. Moreover, we are allowed to substitute one of the dependent variables from one of the equations into the other, leading to an equivalent fourth‐order nonlinear ordinary differential equation. This equation is reduced through the use of solvable symmetry subalgebras, and some exact solutions are obtained for a particular case. [ABSTRACT FROM AUTHOR]

A generalization of the time-delayed Burgers–Fisher equation is studied. This partial differential equation appears in many physical and biological problems describing the interaction between reaction, diffusion, and convection. New travelling wave solutions are obtained. The solutions are derived in a systematic way by applying the multi-reduction method to the symmetry-invariant conservation laws. The translation-invariant conservation law yields a first integral, which is a first-order Chini equation. Under certain conditions on the coefficients of the equation, the Chini type equation obtained can be solved, yielding travelling wave solutions expressed in terms of the Lerch transcendent function. For a special case, the first integral becomes a Riccati equation, whose solutions are given in terms of Bessel functions, and for a special case of the parameters, the solutions are given in terms of exponential, trigonometric, and hyperbolic functions. Furthermore, a complete classification of the zeroth-order local conservation laws is obtained. To the best of our knowledge, our results include new solutions that have not been previously reported in the literature. [ABSTRACT FROM AUTHOR]

In this work, we consider a family of nonlinear third-order evolution equations, where two arbitrary functions depending on the dependent variable appear. Evolution equations of this type model several real-world phenomena, such as diffusion, convection, or dispersion processes, only to cite a few. By using the multiplier method, we compute conservation laws. Looking for traveling waves solutions, all the the conservation laws that are invariant under translation symmetries are directly obtained. Moreover, each of them will be inherited by the corresponding traveling wave ODEs, and a set of first integrals are obtained, allowing to reduce the nonlinear third-order evolution equations under consideration into a first-order autonomous equation. [ABSTRACT FROM AUTHOR]

In this paper, we show direct connections between the conservation law (CL)-based method and the differential invariant (DI)-based method for obtaining nonlocally related systems and nonlocal symmetries for a given partial differential equation (PDE) system. For a PDE system with two independent variables, we show that the CL method is a special case for the DI method. For a PDE system with at least three independent variables, we show that the CL method, for a curl-type CL, is a special case for the DI method. We also consider the situation for a self-adjoint, i.e. variational, linear PDE system. Here, a solution of the linear PDE system yields a nonlocally related system for both approaches. In particular, the resulting nonlocally related systems need not be invertibly equivalent. Through an example, we show that three distinct nonlocally related systems can be obtained from an admitted point symmetry. [ABSTRACT FROM AUTHOR]

Nonlocally related systems, obtained through conservation law and symmetry-based methods, have proved to be useful for determining nonlocal symmetries, nonlocal conservation laws, non-invertible mappings and new exact solutions of a given partial differential equation (PDE) system. In this paper, it is shown that the symmetry-based method is a differential invariant-based method. It is shown that this allows one to naturally extend the symmetry-based method to ordinary differential equation (ODE) systems and to PDE systems with at least three independent variables. In particular, we present the situations for ODE systems, PDE systems with two independent variables and PDE systems with three or more independent variables, separately, and show that these three situations are directly connected. Examples are exhibited for each of the three situations. [ABSTRACT FROM AUTHOR]

Nonlocally related partial differential equation (PDE) systems can play an important role in the analysis of a given PDE system. In this paper, a new systematic method for obtaining nonlocally related PDE systems is developed. In particular, it is shown that if a PDE system admits q point symmetries whose infinitesimal generators form a q-dimensional solvable Lie algebra, then, for each resulting q-dimensional solvable algebra chain, one can obtain systematically q nonlocally related PDE systems. Such nonlocally related systems are obtained for a general class of nonlinear reaction–diffusion equations admitting two- to four-dimensional solvable algebras. [ABSTRACT FROM AUTHOR]

A family of third-order partial differential equations (PDEs) is analyzed. This family broadens out well-known PDEs such as the Korteweg-de Vries equation, the Gardner equation, and the Burgers equation, which model many real-world phenomena. Furthermore, several macroscopic models for semiconductors considering quantum effects—for example, models for the transmission of electrical lines and quantum hydrodynamic models—are governed by third-order PDEs of this family. For this family, all point symmetries have been derived. These symmetries are used to determine group-invariant solutions from three-dimensional solvable subgroups of the complete symmetry group, which allow us to reduce the given PDE to a first-order nonlinear ordinary differential equation (ODE). Finally, exact solutions are obtained by solving the first-order nonlinear ODEs or by taking into account the Type-II hidden symmetries that appear in the reduced second-order ODEs. [ABSTRACT FROM AUTHOR]

Conclusion. We tested one prototype of a new audioprosthesis including the audioprocessor, the implemented algorithms and fitting platform in a small group of selected patients with mixed hypoacusis due to earlier bilateral radical mastoidectomy. It was effective to compensate the conductive and the neurosensory components of those patients. Results regarding the energy, frequency and other requirements of the output transduction make it possible to develop a suitable actuator with the available Micro-Electromechanic-Machine-System (MEMS) technology to substitute the conventional transducer of the prototype. Objectives. The objectives were: a) to evaluate the effectiveness of the whole fitting system, and b) to obtain information about the required energy to design the MEMS actuator. Materials and methods. The experiments were conducted with the A prototype of the prosthesis equipped with an output transducer coupled to the oval window. Two algorithms and three cases were tested. Results. The audioprocessor with the implemented FIR filter-67 coefficients paradigm algorithms, and the fitting system were shown to be adequate for clinical use. Effectiveness parameters were: pure tone average gains 20-33.3 dB; gap closure 25.5-31.8 dB; speech reception thresholds improvement 15-20 dB. Required gain: 5-40 dB. Subjectively, patients considered the results very satisfactory. [ABSTRACT FROM AUTHOR]

Background: Our study aims to comment on all ADPKD variants identified in our health area and explain how they are distributed geographically, to identify new variants, and relate the more frequent variants with their renal phenotype in terms of kidney survival. Materials and Methods: We identified patients suffering from ADPKD in a specialized consultation unit; genealogical trees were constructed from the proband. According to the ultrasound-defined modified Ravine–Pei criteria, relatives classified as at risk were offered participation in the genetic study. Socio-demographic, clinical, and genetic factors related to the impact of the variant on the survival of the kidney and the patient, such as age at RRT beginning and age of death, were recorded. Results: In 37 families, 33 new variants of the PKD1 gene were identified, which probably produce a truncated protein. These variants included 2 large deletions, 19 frameshifts, and 12 stop-codons, all of which had not been previously described in the databases. In 10 families, six new probably pathogenic variants in the PKD2 gene were identified. These included three substitutions; two deletions, one of which was intronic and not associated with any family; and one duplication. A total of 11 missense variants in the PKD1 gene were grouped in 14 families and classified as probably pathogenic. We found that 33 VUS were grouped into 18 families and were not described in the databases, while another 15 were without grouping, and there was only 1 in the PKD2 gene. Some of these variants were present in patients with a different pathogenic variant (described or not), and the variant was probably benign. Renal survival curves were compared to nonsense versus missense variants on the PKD1 gene to check if there were any differences. A group of 328 patients with a nonsense variant was compared with a group of 264 with a missense variant; mean renal survival for truncated variants was lower (53.1 ± 0.46 years versus non-truncated variant 59.1 ± 1.36 years; Log Rank, Breslow, and Tarone Ware, p < 0.05). Conclusions: To learn more about ADPKD, it is necessary to understand genetics. By describing new genetic variants, we are approaching creation of an accurate genetic map of the disease in our country, which could have prognostic and therapeutic implications in the future. [ABSTRACT FROM AUTHOR]

Deals with a study which described the evolution of infections in a group of HIV-infected patients with latent visceral leishmaniasis (VL) who received antiretroviral therapy after VL was diagnosed. Background on the introduction of highly active antiretroviral therapy; Methodology; Results and discussion.

This paper considers a generalized thin film equation in two spatial dimensions depending on three arbitrary functions. This equation describes the time evolution of a Newtonian liquid that is considerably thinner in one direction than in the other directions. We include a classification of point symmetries and the corresponding transformation groups. We derive all low-order local conservation laws of the equation in terms of the arbitrary functions. In addition, we discuss the physical meaning of the conserved quantities and provide a useful conservation identity. [ABSTRACT FROM AUTHOR]

In this paper, we consider a fourth‐order nonlinear diffusion partial differential equation, depending on two arbitrary functions. First, we perform an analysis of the symmetry reductions for this parabolic partial differential equation by applying the Lie symmetry method. The invariance property of a partial differential equation under a Lie group of transformations yields the infinitesimal generators. By using this invariance condition, we present a complete classification of the Lie point symmetries for the different forms of the functions that the partial differential equation involves. Afterwards, the optimal systems of one‐dimensional subalgebras for each maximal Lie algebra are determined, by computing previously the commutation relations, with the Lie bracket operator, and the adjoint representation. Next, the reductions to ordinary differential equations are derived from the optimal systems of one‐dimensional subalgebras. Furthermore, we study travelling wave reductions depending on the form of the two arbitrary functions of the original equation. Some travelling wave solutions are obtained, such as solitons, kinks and periodic waves. [ABSTRACT FROM AUTHOR]

The Benjamin–Bona–Mahony equation describes the unidirectional propagation of small-amplitude long waves on the surface of water in a channel. In this paper, we consider a family of generalized Benjamin–Bona–Mahony–Burgers equations depending on three arbitrary constants and an arbitrary function G (u) . We study this family from the standpoint of the theory of symmetry reductions of partial differential equations. Firstly, we obtain the Lie point symmetries admitted by the considered family. Moreover, taking into account the admitted point symmetries, we perform symmetry reductions. In particular, for G ′ (u) ≠ 0 , we construct an optimal system of one-dimensional subalgebras for each maximal Lie algebra and deduce the corresponding (1+1)-dimensional nonlinear third-order partial differential equations. Then, we apply Kudryashov's method to look for exact solutions of the nonlinear differential equation. We also determine line soliton solutions of the family of equations in a particular case. Lastly, through the multipliers method, we have constructed low-order conservation laws admitted by the family of equations. [ABSTRACT FROM AUTHOR]

In this work, we present a model for the automatic generation of written dialogues, through the use of grammatical inference. This model allows the automatic recognition of grammars from a set dialogues employed as a training set. The inferred grammars are then used to generate templates of responses within the dialogues. The final objective is to apply this model in a specific domain dialogue system that answers questions in Spanish with the use of a knowledge base. The experiments carried out have been performend using the DIHANA project corpus which contains dialogues written in Spanish about schedules and prices of a rail system. [ABSTRACT FROM AUTHOR]

This paper considers a generalized double dispersion equation depending on a nonlinear function f (u) and four arbitrary parameters. This equation describes nonlinear dispersive waves in 2 + 1 dimensions and admits a Lagrangian formulation when it is expressed in terms of a potential variable. In this case, the associated Hamiltonian structure is obtained. We classify all of the Lie symmetries (point and contact) and present the corresponding symmetry transformation groups. Finally, we derive the conservation laws from those symmetries that are variational, and we discuss the physical meaning of the corresponding conserved quantities. [ABSTRACT FROM AUTHOR]

Persistent cytomegalovirus (CMV) infection has been suggested to be a major driving force in the immune deterioration and an underlying source of age-related diseases in the elderly. CMV antibody titers are associated with lower responses to vaccination, cardiovascular diseases, frailty, and mortality. CMV infection is also associated with shorter T-cell telomeres and replicative senescence. Although an age-related deregulation of CMV-specific T-cell responses could be an underlying cause of the relationship between CMV and immune defects, strong and polyfunctional responses are observed in elderly individuals, casting uncertainty on their direct role in age-related immune frailty. In this study, we longitudinally followed a cohort of healthy donors aged over 50 years, assessing their mortality rates and time to death during a 2-year period. Specific T-cell responses to the immunodominant antigen pp65 (IFNγ, TNFα, IL2, MIP1α, CD107a, and perforin production) were analyzed at the beginning of the 2-year observation period. A cytotoxic CD8 pp65-specific T-cell response, without cytokine or chemokine coexpression, was independently associated with all-cause mortality in these elderly individuals. This pp65-specific CD8 T-cell response could be a useful tool to identify individuals with depressed immune function and a higher risk of death. [ABSTRACT FROM AUTHOR]

In this paper a tool for supporting visual analysis of the behavior of metaheuristic algorithms focused to solve the Bin Packing Problem is proposed. Traditionally, metaheuristics have been analyzed monolithically, by means of solving a set of input instances and analyzing the output solutions. However, due to the stochastic features of metaheuristics, for a given instance and several executions of a metaheuristic, solutions may be excellent as the optimal solution or can be bad as the worst solution, which makes difficult to understand the behavior of the metaheuristic algorithm. In this sense, the proposed tool allows storing and reproducing the algorithm behavior during any execution making possible the metaheuristic analysis and improvement. To validate the tool the Hybrid Grouping Genetic Algorithm for Bin Packing (HGGA&lowbar;BP) was analyzed while it was solving the WAE&lowbar;GAU1 benchmark of instances. Based on the analysis results some improvements to the metaheuristic algorithm were identified. The improvements allowed increasing the metaheuristic efficiency by 48%. [ABSTRACT FROM AUTHOR]

The article analyzes the predictive capacity of thymic volume in CD4 T-cell loss after prolonged treatment interruption in a group of immunologically preserved HIV-infected patients with nadir CD4 count greater than 250 cells/µL. Multivariate Cox proportional hazards regression models were used to analyze all variables with statistical association with CD4 T-cell loss. Twenty-three percent of the patients had a reduction in CD4 count to less than 350 cells/µL. Thymic volume and CD4 T-cell loss were independently associated using the model.

Genotyping of human immunodeficiency virus type 1 (HIV-1) for antiretroviral drug resistance is routinely used both in clinical practice, to guide the selection of options for an individual's antiretroviral therapy, and in epidemiological studies, to estimate levels of antiretroviral drug resistance in a patient population. However, reliance on results of a single test can result in an underestimation of antiretroviral drug resistance. In the present study, we quantified the prevalence of resistance-associated mutations found in recent genotypic tests of 1734 HIV-1-infected, treatment-experienced subjects who had at least 3 genotypic tests ( genotypic np11,404 tests total; median, 5 tests/subject) and compared it with that of resistance-associated mutations ever detected in these subjects between 1996 and 2004. Single-point analyses underestimated antiretroviral drug resistance, particularly for nucleoside analogues, in both individuals and patient populations. For example, the prevalence of resistance-associated mutation M184V/I was 25.5% in the most recent genotypes and 58.8% in available historical genotypes. Our results suggest that analysis of a combined historical genotype rather than of a crosssectional genotype may lead to more accurate estimates of antiretroviral drug resistance in individual patients and in patient populations. [ABSTRACT FROM AUTHOR]

Thymic function was evaluated in 32 heavily antiretroviral-treated human immunodeficiency virus type 1 (HIV-1)-infected adults with long-term virologic treatment failure by measuring thymic volume, by determining the absolute number of naive T cell phenotypes, and by determining the number of cells carrying T cell receptor excision circles (TRECs). There was a significant inverse correlation between age and thymic volume (r = -0.415; P = .018), and there was a significant direct correlation between thymic volume and total naive T cell counts (r = 0.529; P = .002), naive CD4[sup +] cell counts (r = 0.437; P = .012), naive CD8[sup +] cell counts (r = 0.467; P = .007), and TREC levels (r = 0.391; P = .027). In conclusion, this study found clear evidence that the thymus of heavily antiretroviral-treated HIV-l-infected adults with long-term virologic treatment failure is actively engaged in thymopoiesis, which generates new naive T cells for the peripheral lymphocyte pool. [ABSTRACT FROM AUTHOR]

In this work, we study a generalised (2 + 1) equation of the Zakharov–Kuznetsov (ZK) (m , n , k) equation involving three arbitrary functions. From the point of view of the Lie symmetry theory, we have derived all Lie symmetries of this equation depending on the arbitrary functions. Line soliton solutions have also been obtained. Moreover, we study the low-order conservation laws by applying the multiplier method. This family of equations is rich in Lie symmetries and conservation laws. Finally, when the equation is expressed in potential form, it admits a variational structure in the case when two of the arbitrary functions are linear. In addition, the corresponding Hamiltonian formulation is presented. [ABSTRACT FROM AUTHOR]