FES rehabilitation platform with real-time control and performance feedback.

Osteoporosis after spinal cord injury is associated with low-trauma fractures, and consequently with increased risk of morbidity and mortality. The loss of bone mass density (BMD) due to paraplegia can be reduced through cyclical electrically-induced muscle contractions. Here we propose an FES control system based on posture switching, that induces transient loading of the lower limbs during a set of standing postures. This aims to produce an increased, evenly distributed BMD, whilst minimising FES-induced muscle fatigue. Here we describe the design and assessment of the FES exercising platform, comprising a controllable multi-channel electrical stimulator and an instrumented standing frame. The platform supports standing and postural shifting, provides real-time human-in-the-loop FES control with on-line feedback to the user. The platforms is used to investigate the effect of regular exercise on the distribution of BMD in people with paraplegia

The local period function for Hamiltonian systems with applications

In the first part of the paper we develop a constructive procedure to obtain the Taylor expansion, in terms of the energy, of the period function for a non-degenerated center of any planar analytic Hamiltonian system. We apply it to several examples, including the whirling pendulum and a cubic Hamiltonian system. The knowledge of this Taylor expansion of the period function for this system is one of the key points to study the number of zeroes of an Abelian integral that controls the number of limit cycles bifurcating from the periodic orbits of a planar Hamiltonian system that is inspired by a physical model on capillarity. Several other classical tools, like for instance Chebyshev systems are applied to study this number of zeroes. The approach introduced can also be applied in other situations.Comment: 23 page

Pattern of degeneration of the rat inferior olivary complex after the early postnatal axotomy of the olivocerebellar projection

Neuronal death of inferior olivary neurons after early axotomy of the olivocerebellar tract was studied in newborn (Pl) hemicerebellectomized rats during the first six days after lesion. The degeneration of the inferior olive showed a topographic pattem from one (P2) to six days after axotomy (P7), after which this complex had almost completely disappeared. The first degenerative changes were observed in the principal olive (P2), while the media1 accessory olive was the later-degenerated area (P5). The analysis of these degenerative changes provides a reference for future experimental studies. Furthermore, the topographic study of the degenerative process demonstrated that: i) the most vulnerable neurons were dorsolaterally located, whereas the most resistant ones occupied the media1 aspect of the inferior olivary complex, ii) the comparison between the topographical arrangement of the inferior olivary neurons according to their birth dates, and the rate of degenerative changes observed after hemicerebellectomy, open the possibility that the neurona1 generation date and the response to the axotomy of the inferior olivary neurons could be related

Global periodicity conditions for maps and recurrences via Normal Forms

We face the problem of characterizing the periodic cases in parametric families of (real or complex) rational diffeomorphisms having a fixed point. Our approach relies on the Normal Form Theory, to obtain necessary conditions for the existence of a formal linearization of the map, and on the introduction of a suitable rational parametrization of the parameters of the family. Using these tools we can find a finite set of values p for which the map can be p-periodic, reducing the problem of finding the parameters for which the periodic cases appear to simple computations. We apply our results to several two and three dimensional classes of polynomial or rational maps. In particular we find the global periodic cases for several Lyness type recurrences.Comment: 25 page

Evolución del germen dental trasplantado heterotópicamente en la dermis: un estudio histológico en la rata

En este estudio hemos analizado la potencialidad de desarrollo del germen dental en fase de corona. Para ello, los gérmenes dentales de rata recién nacida fueron trasplantados en las bolsas dérmicas de la oreja de ratas isogénicas. Siete y catorce días después del trasplante, se desarrollaron las estructuras morfológicas dentales típicas, con ameloblastos y odontoblastos bien diferenciados. Ulteriormente, los procesos de reacción inflamatoria del tejido huésped con infiltración celular abocaron a la desaparición de los tejidos dentales. Desde el primer momento de nuestro análisis, los trasplantes desarrollaron una dentina anómala u osteoide cuyo tamaño fue paulatinamente incrementando con el tiempo, llegando a sustituir al resto de los tejidos dentales. Esta dentina osteoide, fruto tanto de la transformación de los odontoblastos del trasplante en células de alta actividad secretora como de la inducción que el germen dental ejerce en el tejido huésped circundante; y a diferencia de la observada en estudios previos, mostró diversos grados de polimerización fibrilar, lo que nos induce a sugerir que nuestro modelo puede ser un buen medio de estudiar los mecanismos de reacción en la formación de tejidos reactivos a la lesión dental.The main goal of this study was the analysis of the developmental potentiality of tooth germ from late bell stage on, after its heterotopic placement within the skin. Teeth germs of newborn rats were grafted within a skin pouch of the ear of adult rats. Seven to fourteen days after grafting, dental germs developed normal dental structures in which ameloblasts and odontoblasts were well differentiated. Twenty to forty-one days after graft, the inflammatory host reaction destroyed the dental developed tissues by cell infiltration. The dentin of the grafts was of osteoid characteristics, and its size increased dependinng on grafting time until the complete substitution of all dental tissues. This atypical dentin showed several degrees of polymerisation from collagen fibres smooth dentin devoid near the graft a to fibres rich dentin far from the dental germ. Present results suggest that this type of dental graft could be a valuable model to study the self-development of dental tissues and the reactive mechanisms taking place after dental injuries

Some results on homoclinic and heteroclinic connections in planar systems

Consider a family of planar systems depending on two parameters $(n,b)$ and having at most one limit cycle. Assume that the limit cycle disappears at some homoclinic (or heteroclinic) connection when $\Phi(n,b)=0.$ We present a method that allows to obtain a sequence of explicit algebraic lower and upper bounds for the bifurcation set ${\Phi(n,b)=0}.$ The method is applied to two quadratic families, one of them is the well-known Bogdanov-Takens system. One of the results that we obtain for this system is the bifurcation curve for small values of $n$, given by $b=\frac5 7 n^{1/2}+{72/2401}n- {30024/45294865}n^{3/2}- {2352961656/11108339166925} n^2+O(n^{5/2})$. We obtain the new three terms from purely algebraic calculations, without evaluating Melnikov functions

Credence cues of pork are more important than consumers' culinary skills to boost their purchasing intention

The role of consumers' culinary skills on purchasing cues of pork, with emphasis on niche demands (outdoor husbandry and/or certified organic), was assessed in cross-country regions of Spain (Catalonia and Aragon) and Portugal (North). A sample of 974 respondents answered an on-line survey with questions regarding consumer purchasing habits, product involvement and intrinsic and credence attributes. They also chose between two contrasting boneless pork loins and express willingness to pay (WTP) for different product scenarios with different pig farm facilities and for organic pork standards. Two optimal segments were identified based on food-related habits: ‘uninvolved’ and ‘innovative cook lovers’, both similarly balanced across socio-demographics, score for credence attributes or consumer involvement dimensions. Overall mean WTP premium across countries was 11.8% for marbled pork, 20.0% for outdoor pork and 24.3% for organic logo stamp. Credence cues of pork claiming health issues (absence of antibiotics and hormone residues) rather than consumers' culinary skills defined the WTP for niche pork in these regions