56 documents found, page 1 of 6
Homotopy analysis of explicit series solutions in a modified Nosé-Hoover oscill...
Deng, Bo; Duarte, Jorge; Januário, Cristina; Martins, NunoIn light of recent advancements in the literature concerning the Homotopy Analysis Method (HAM), this paper introduces a stepwise homotopy analysis methodology. This approach is employed to derive explicit series solutions for a generalized Nosé-Hoover oscillator. Using an optimized homotopy analysis strategy, the computational efficiency of HAM is enhanced through small step intervals, significantly expediting...
A standardised protocol for blood and cerebrospinal fluid collection and proces...
Santana, Magda M.; Gaspar, Laetitia S.; Pinto, Maria M.; Silva, Patrick Joel da; Adão, Diana; Pereira, Dina; Ribeiro, Joana Afonso; Cunha, InêsThe European Spinocerebellar Ataxia Type 3/Machado-Joseph Disease Initiative (ESMI) is a consortium established with the ambition to set up the largest European longitudinal trial-ready cohort of Spinocerebellar Ataxia Type 3/Machado-Joseph Disease (SCA3/MJD), the most common autosomal dominantly inherited ataxia worldwide. A major focus of ESMI has been the identification of SCA3/MJD biomarkers to enable futur...
Measuring cognitive impairment and monitoring cognitive decline in Huntington's...
Horta-Barba, Andrea; Martinez-Horta, Saul; Pérez-Pérez, Jesús; Puig-Davi, Arnau; de Lucia, Natascia; de Michele, Giuseppe; Salvatore, ElenaBackground Progressive cognitive decline is an inevitable feature of Huntington’s disease (HD) but specific criteria and instruments are still insufficiently developed to reliably classify patients into categories of cognitive severity and to monitor the progression of cognitive impairment. Methods We collected data from a cohort of 180 positive gene-carriers: 33 with premanifest HD and 147 with manifest HD. Us...
Measures of complexity in Nosé-Hoover oscillator and a possible new chaos gener...
Deng, Bo; Duarte, Jorge; Januário, Cristina; Martins, NunoIn this article, we undertake a study of the time-reversible dynamiics of the original Nosé-Hoover oscillator with the aim to identify its nontrivial chaos generating pathway. We examined the spectrum of Lyapunov exponent, predictability, and fractal dimension of both for- ward and backward chaotic attractors. We failed to identify any known chaos type that can explain our findings. We propose a new chaos gener...
On the chaotic dynamics of a modified Nosé-Hoover oscillator
Deng, Bo; Duarte, Jorge; Januário, Cristina; Martins, NunoThis article reports on a study of the two-dimensional parameter space of a generalized time-reversible Nosé-Hoover oscillator. Instead of considering its original form, whose study of the one-dimensional parameter space has recently received new insights, we examine the Nosé-Hoover model slightly modified by using a new parameter ε to introduce a dissipative term to its energizing-damping variable. We use the ...
Cerebellar morphometric and spectroscopic biomarkers for Machado-Joseph Disease
Miranda, Catarina Oliveira; Nobre, Rui Jorge; Paiva, Vítor Hugo; Duarte, João Valente; Castelhano, João; Petrella, Lorena Itati; Sereno, JoséMachado-Joseph disease (MJD) or Spinocerebellar ataxia type 3 (SCA3) is the most common form of dominant SCA worldwide. Magnetic Resonance Imaging (MRI) and Proton Magnetic Resonance Spectroscopy (1H-MRS) provide promising non-invasive diagnostic and follow-up tools, also serving to evaluate therapies efficacy. However, pre-clinical studies showing relationship between MRI-MRS based biomarkers and functional pe...
Classification of Huntington's Disease Stage with Features Derived from Structu...
Lavrador, Rui Filipe David; Júlio, Filipa; Januário, Cristina; Castelo Branco, Miguel; Caetano, GinaThe purpose of this study was to classify Huntington's disease (HD) stage using support vector machines and measures derived from T1- and diffusion-weighted imaging. The effects of feature selection approach and combination of imaging modalities are assessed. Fourteen premanifest-HD individuals (Pre-HD; on average > 20 years from estimated disease onset), eleven early-manifest HD (Early-HD) patients, and eighte...
A SIR forced model with interplays with the external world and periodic interna...
d'Onofrio, Alberto; Duarte, Jorge; Januário, Cristina; Martins, NunoWe investigated the behavior of a Susceptible-Infected-Recovered seasonally forced model for endemic childhood infectious diseases in the case where the target population is not isolated and, moreover, fast weekly fluctuations of the social contacts occur. We considered some key scenarios of interplay of Susceptible subjects with the external world, leading to subharmonic resonances and chaos. Our simulations s...
A link between synaptic plasticity and reorganization of brain activity in Park...
Rebelo, Diliana; Oliveira, Francisco; Abrunhosa, Antero; Januário, Cristina; Lemos, João; Castelo-Branco, MiguelThe link between synaptic plasticity and reorganization of brain activity in health and disease remains a scientific challenge. We examined this question in Parkinson's disease (PD) where functional up-regulation of postsynaptic D2 receptors has been documented while its significance at the neural activity level has never been identified. We investigated cortico-subcortical plasticity in PD using the oculomotor...
Homotopy analysis of explicit solutions in a chronic hepatitis C virus model
Duarte, Jorge; Januário, Cristina; Martins, NunoMathematical analysis of nonlinear models in epidemiology has generated a deep interest in gaining insights into the mechanisms that underlie hepatitis C virus (HCV) infections. In this article, we provide a study of a chronic HCV infection model with immune response, incorporating the effect of dendritic cells (DC) and cytotoxic T lymphocytes (CTL). Considering very recent developments in the literature relate...