First order transitions by conduction calorimetry: Application to deuterated potassium dihydrogen phosphate ferroelastic crystal under uniaxial pressure

The specific heat c and the heat power W exchanged by a Deuterated Potassium Dihydrogen Phosphate ferroelectric-ferroelastic crystal have been measured simultaneously for both decreasing and increasing temperature at a low constant rate (0.06 K/h) between 175 and 240 K. The measurements were carried out under controlled uniaxial stresses of 0.3 and 4.5±0.1 bar applied to face (110). At Tt=207.9 K, a first order transition is produced with anomalous specific heat behavior in the interval where the transition heat appears. This anomalous behavior is explained in terms of the temperature variation of the heat power during the transition. During cooling, the transition occurs with coexistence of phases, while during heating it seems that metastable states are reached. Excluding data affected by the transition heat, the specific heat behavior agrees with the predictions of a 2-4-6 Landau potential in the range of 4–15 K below Tt while logarithmic behavior is obtained in the range from Tt to 1 K below Tt. Data obtained under 0.3 and 4.5 bar uniaxial stresses exhibit the same behavior.Dirección General de Investigación Científica y Técnica. Gobierno de España-PB91-60

Memory effect in triglycine sulfate induced by a transverse electric field: specific heat measurement

The influence of a transverse electric field in the specific heat of triglycine sulphate (TGS) has been studied. The specific heat of TGS has been measured heating the sample from ferroelectric to paraelectric phase after prolonged transverse electric field (i.e. perpendicular to the ferroelectric axis). It is shown that the specific heat of TGS can remember the temperature $T_s$ at which the transverse field was previously applied.Comment: ReVTeX4 Twocolumn 4 pages, 4 figure

Stem cells as a therapeutic tool for the blind: biology and future prospects

Retinal degeneration due to genetic, diabetic and age-related disease is the most common cause of blindness in the developed world. Blindness occurs through the loss of the light-sensing photoreceptors; to restore vision, it would be necessary to introduce alternative photosensitive components into the eye. The recent development of an electronic prosthesis placed beneath the severely diseased retina has shown that subretinal stimulation may restore some visual function in blind patients. This proves that residual retinal circuits can be reawakened after photoreceptor loss and defines a goal for stem-cell-based therapy to replace photoreceptors. Advances in reprogramming adult cells have shown how it may be possible to generate autologous stem cells for transplantation without the need for an embryo donor. The recent success in culturing a whole optic cup in vitro has shown how large numbers of photoreceptors might be generated from embryonic stem cells. Taken together, these threads of discovery provide the basis for optimism for the development of a stem-cell-based strategy for the treatment of retinal blindness

“De Portugal a Castela”. Doña M.ª Guadalupe de Lancaster, duquesa de Aveiro. Conflictos y resistencias de una aristócrata en época barroca (1630-1715)

The New Biography, so called Biographic History, represents a renewed perspective of the Biographical Genre which expands the analytical and narrative possibilities when facing studies on life couses and constractions of subjetivities. From this approach, and together with the method of microhistory, this article looks at the trajectory of the life of the Duchess of Aveiro, Lady Guadalupe de Lancaster, along an itinerary between Portugal and Spain between 1630 and 1715. In this double scenario, you will observe her personal and family journey incardinated in the respective contexts, analyzing the historical, political and cultural avatars that determined the configuration of her indi- vidual identities as a daughter, wife and mother and as a member of the high nobility. Heiress of the House of Aveiro, she starred in a long conflict against her husband, the Duke of Arcos, who opposed the rights that assisted her, a position that resulted in the separation of the marriage. On the other hand, its aristocratic origins and its membership in the Court, constitute an opportunity to peek into the courtly universe as a microcosm of rivalries, betrayals and complicated intricacies coexisted that the Duchess knew and in those she knew how to operate with ease.La nueva biografía, también llamada historia biográfica, constituye una perspectiva renovada del género biográfico que ha ensanchado las posibilidades analíticas y narrativas de los estudios sobre cursos de vida y construcción de las subjetividades. Desde este enfoque, y junto al método de la microhistoria, el presente artículo vierte una mirada sobre la trayectoria de vida de doña Guadalupe de Lancaster, duquesa de Aveiro, a lo largo de un itinerario acontecido entre Portugal y España desde 1630 a 1715. En este doble escenario, se observará su recorrido personal y familiar incardinado en los respectivos contextos, analizando los avatares históricos, políticos y culturales determinantes en la configuración de sus identidades individuales como hija, esposa y madre a la par que miembro de la alta nobleza. Heredera de la casa de Aveiro, protagonizó un largo conflicto contra su esposo, el duque de Arcos, por su oposición a los derechos que la asistían, tesitura que derivó en la separación matrimonial. Por otro lado, sus orígenes aristocráticos y su pertenencia a la corte constituyen una oportunidad para asomarse al universo cortesano como microcosmo donde convivieron rivalidades, traiciones y complicidades; entresijos que la duquesa conocía y en los que supo operar con desenvoltura

Procedimiento metodológico para implicar a los profesionales de especialidades técnicas y carreras universitarias en la evaluación del proceso de formación de sus habilidades profesionales asumiendo un enfoque de competencias

The work shows a methodological procedure that allows to imply the professionals in process of formation of technical specialties and university careers in the evaluation of the process of formation of its professional abilities assuming for it a focus of competitions. For he/she intends a system of indicators with their corresponding scales of valuation that allow to end up dominating the level that the students reach in the formation of the same ones; as well as, the regulation of the one referred process with effectiveness, without ignoring the affective of the personality and the educational of the process.El trabajo muestra un procedimiento metodológico que permite implicar a los profesionales en proceso de formación de especialidades técnicas y carreras universitarias, en la evaluación del proceso de formación de sus habilidades profesionales, asumiendo para ello un enfoque de competencias. Para tal efecto, se propone un sistema de indicadores con sus correspondientes escalas de valoración, que permite llegar a dominar el nivel que los estudiantes alcanzan en la formación de las mismas, así como la regulación del referido proceso con efectividad, sin ignorar lo afectivo de la personalidad y lo educativo del proceso

Influence of the electric field on the latent heat of the ferroelectric phase transition in KDP

The specific heat, heat flux (DTA trace) and dielectric constant of KDP ferroelectric crystal have been measured simultaneously for various electric fields with a conduction calorimeter. The specific heat presents a strong anomaly but these simultaneous measurements allow us to evaluate the latent heat accurately. Latent heat decreases with field and the value of critical electric field --that where latent heat disappears-- is estimated to be (0.44\pm0.03) kV/cm. Incidentally, we have measured simultaneously the dielectric permittivity which suggests that latent heat is developed as domains are growing.Comment: 7 pages, 6 figures, ReVTeX, twocolumn format, to appear in J. Phys. Cond. Matte

Modelling and Analysis of Vibrations in a UAV Helicopter with a Vision System

The analysis of the nature and damping of unwanted vibrations on Unmanned Aerial Vehicle (UAV) helicopters are important tasks when images from on‐board vision systems are to be obtained. In this article, the authors model a UAV system, generate a range of vibrations originating in the main rotor and design a control methodology in order to damp these vibrations. The UAV is modelled using VehicleSim, the vibrations that appear on the fuselage are analysed to study their effects on the on‐board vision system by using Simmechanics software. Following this, the authors present a control method based on an Adaptive Neuro‐Fuzzy Inference System (ANFIS) to achieve satisfactory damping results over the vision system on board

Intraocular retinal transplants

Embryonic rat retinae transplanted into the anterior chamber of adult rat eyes of the same or different strain survive and grow. Light and electron microscopic studies show that the transplants undergo histogenetic differentiation, resulting in the development of mature inner and outer layer neurons and Muller glial cells. Vascular connections develop between the host iris and the retinal transplant. These initial observations indicate that retinal transplantation to a recipient eye is a procedure which offers ample opportunities for the study of problems related to neural development, retinal plasticity and repair