Static and Dynamic Nonlinearity of A/D Converters

The dynamic range of broadband digital system is mostly limited by harmonics and spurious arising from ADC nonlinearity. The nonlinearity may be described in several ways. The distinction between static and dynamic contributions has strong theoretical motivations but it is difficult to independently measure these contributions. A more practical approach is based upon analysis of the complex spectrum, which is well defined, easily measured, and may be used to optimize the ADC working point and to somehow characterize both static and dynamic nonlinearity. To minimize harmonics and spurious components we need a sufficient level of input noise (dither), which destroys the periodicity at multistage pipelined ADC, combined with a careful analysis of the different sources of nonlinearity

Circulating progenitor cells during exercise, muscle electro-stimulation and intermittent hypobaric hypoxia in patients with traumatic brain injury. A pilot study

BACKGROUND: Circulating progenitor cells (CPC) treatments may have great potential for the recovery of neurons and brain function. OBJECTIVE: To increase and maintain CPC with a program of exercise, muscle electro-stimulation (ME) and/or intermittent-hypobaric-hypoxia (IHH), and also to study the possible improvement in physical or psychological functioning of participants with Traumatic Brain Injury (TBI). METHODS: Twenty-one participants. Four groups: exercise and ME group (EEG), cycling group (CyG), IHH and ME group (HEG) and control group (CG). Psychological and physical stress tests were carried out. CPC were measured in blood several times during the protocol. RESULTS: Psychological tests did not change. In the physical stress tests the VO2 uptake increased in the EEG and the CyG, and the maximal tolerated workload increased in the HEG. CPC levels increased in the last three weeks in EEG, but not in CyG, CG and HEG. CONCLUSIONS: CPC levels increased in the last three weeks of the EEG program, but not in the other groups and we did not detect performed psychological test changes in any group. The detected aerobic capacity or workload improvement must be beneficial for the patients who have suffered TBI, but exercise type and the mechanisms involved are not clear

Combined intermittent hypobaric hypoxia and muscle electro-stimulation: a method to increase circulating progenitor cell concentration?

Our goal was to test whether short-term intermittent hypobaric hypoxia (IHH) at a level well tolerated by healthy humans could, in combination with muscle electro-stimulation (ME), mobilize circulating progenitor cells (CPC) and increase their concentration in peripheral circulation. Nine healthy male subjects were subjected, as the active group (HME), to a protocol involving IHH plus ME. IHH exposure consisted of four, three-hour sessions at a barometric pressure of 540 hPa (equivalent to an altitude of 5000 m). These sessions took place on four consecutive days. ME was applied in two separate 20-minute periods during each IHH session. Blood samples were obtained from an antecubital vein on three consecutive days immediately before the experiment, and then 24 h, 48 h, 4 days, 7 days and 14 days after the last day of hypoxic exposure. Four months later a control study was carried out involving seven of the original subjects (CG), who underwent the same protocol of blood samples but without receiving any special stimulus. In comparison with the CG the HME group showed only a non-significant increase in the number of CPC CD34+ cells on the fourth day after the combined IHH and ME treatment. CPC levels oscillated across the study period and provide no firm evidence to support an increased CPC count after IHH plus ME, although it is not possible to know if this slight increase observed is physiologically relevant. Further studies are required to understand CPC dynamics and the physiology and physiopathology of the hypoxic stimulus

Physiological and biological responses to short-term intermittent hypobaric hypoxia exposure: from sports and mountain medicine to new biomedical applications

In recent years, the altitude acclimatization responses elicited by short-term intermittent exposure to hypoxia have been subject to renewed attention. The main goal of short-term intermittent hypobaric hypoxia exposure programs was originally to improve the aerobic capacity of athletes or to accelerate the altitude acclimatization response in alpinists, since such programs induce an increase in erythrocyte mass. Several model programs of intermittent exposure to hypoxia have presented efficiency with respect to this goal, without any of the inconveniences or negative consequences associated with permanent stays at moderate or high altitudes. Artificial intermittent exposure to normobaric hypoxia systems have seen a rapid rise in popularity among recreational and professional athletes, not only due to their unbeatable cost/efficiency ratio, but also because they help prevent common inconveniences associated with high-altitude stays such as social isolation, nutritional limitations, and other minor health and comfort-related annoyances. Today, intermittent exposure to hypobaric hypoxia is known to elicit other physiological response types in several organs and body systems. These responses range from alterations in the ventilatory pattern to modulation of the mitochondrial function. The central role played by hypoxia-inducible factor (HIF) in activating a signaling molecular cascade after hypoxia exposure is well known. Among these targets, several growth factors that upregulate the capillary bed by inducing angiogenesis and promoting oxidative metabolism merit special attention. Applying intermittent hypobaric hypoxia to promote the action of some molecules, such as angiogenic factors, could improve repair and recovery in many tissue types. This article uses a comprehensive approach to examine data obtained in recent years. We consider evidence collected from different tissues, including myocardial capillarization, skeletal muscle fiber types and fiber size changes induced by intermittent hypoxia exposure, and discuss the evidence that points to beneficial interventions in applied fields such as sport science. Short-term intermittent hypoxia may not only be useful for healthy people, but could also be considered a promising tool to be applied, with due caution, to some pathophysiological states

Anàlisis de les capacitats del mòdul Lliçó de Moodle per a la formació en les competències de l’aprenentatge basat en problemes (ABP)

Projecte bianual: 2014PID-UB/037Per fomentar l’autoaprenentatge formatiu i la presa de decisions, hem emprat una eina del Campus Virtual de la Universitat de Barcelona (basat en Moodle), el mòdul Lliçó, per dissenyar recursos amb una orientació pedagògica d’aprenentatge basat en problemes (ABP) de manera que alhora ens permetin recollir informació sobre les accions dels estudiants en el seu ús. Aquests recursos són de tres nivells diferents de complexitat i autonomia segons si les assignatures són de primer i segon nivell dels graus o si són de màster. Com a part de la recerca d’un ajut complementari s’han analitzat els resultats d’ús i s’han establert els criteris a partir dels quals decidim si les eines són adequades per assolir els resultats d’aprenentatge esperats (ja que ens informen del progrés dels estudiants i avaluen aprenentatges i competències adquirides). De les anàlisis de resultats hem determinat els aspectes més interessants per refinar els recursos i fer-los més formatius, i també per aconseguir reduir l’esforç del professorat en l’activitat de tutoria de l’aprenentatge dels seus estudiants. Amb aquesta informació hem introduït modificacions en els recursos. La utilització posterior d’aquests recursos en el proper curs ens ha de permetre usar-los de base en un sistema d’anàlisi de l’aprenentatge (learning analytics) que serà objecte de futures sol·licituds d’ajuts.Ajut 2014 PID - UB / 03

Valoración funcional tras tratamiento neurointensivo pediátrico. Nueva escala de estado funcional (FSS)

Introducción: La salud funcional, parámetro adecuado de morbilidad, debería constituir un estándar pronóstico de las unidades de cuidados intensivos pediátricos (UCIP), siendo fundamental el desarrollo de escalas para su valoración. Las categorías de estado global y cerebral pediátrico (CEGP-CECP) se han empleado clásicamente en estudios pediátricos; el desarrollo de la nueva Escala de estado funcional (FSS) busca mejorar la objetividad. El objetivo del trabajo es comprobar si la escala FSS es un instrumento válido frente a la clásica CEGP-CECP, y si, incluso, posee mejores cualidades evaluadoras de la funcionalidad neurológica. Pacientes y método: Estudio retrospectivo descriptivo de los 266 niños con enfermedad neurológica ingresados en la UCIP durante 3 años (2012-2014). Se valora su salud funcional al alta y tras un año del ingreso en UCIP, según las categorías CEGP-CECP y la nueva FSS, comparando ambas escalas mediante análisis de correlación (Rho de Spearman). Resultados: La comparación de varianzas de FSSglobal en cada intervalo de CEGP muestra buena correlación para todas las comparaciones (p < 0, 001), excepto en la categoría «5 = coma-vegetativo». La dispersión de FSSglobal aumenta a medida que lo hace la categoría CEGP. La correlación es similar en la versión neurológica de ambas escalas. Discusión: La nueva escala FSS parece ser un método útil para evaluar salud funcional en nuestro medio, tras su comparación con las clásicas categorías CEGP-CECP. La dispersión de los valores de la escala FSS indica falta de precisión del sistema CEGP-CECP, comparado con la nueva escala FSS, más desglosada y objetiva

Properties of Blood, Porphyrins, and Exposure to Legacy and Emerging Persistent Organic Pollutants in Surf Scoters (Melanitta perspicillata) Overwintering on the South Coast of British Columbia, Canada

The surf scoter (Melanitta perspicillata) is a little-studied species of North American sea duck. Estimates suggest it has experienced a precipitous decline in breeding numbers over the latter half of the past century. To investigate the potential role of contaminant uptake and toxicity in the population decline, this study undertook to measure blood chemistry, porphyrin concentrations, EROD, and organic contaminants in mature surf scoters wintering in the Strait of Georgia, BC, Canada. Hepatic organochlorine pesticide, polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran, polychlorinated biphenyl (PCB), polybrominated diphenyl ether, and nonylphenol concentrations were relatively low; for example, ΣTEQs (toxic equivalents) for PCBs, dioxins, and furans combined ranged from 4.7 ng/kg wet weight in reference-site (Baynes Sound) birds to 11.4 ng/kg wet weight in birds from Vancouver Harbour. Nonetheless, elevated EROD activity indicated that birds in Howe Sound were responding to an Ah-receptor-mediated stressor, which was also affecting hematocrit values and possibly vitamin A status. In addition, a low proportion of lymphocytes in individuals across locations in early spring samples was associated with poor body condition. The apparent loss of fitness just prior to the onset of northerly migrations to breeding grounds is of particular concern. Compromised health of mature birds at this point in the season might impact negatively on the productivity and survival of some individuals, particularly those overwintering in Howe Sound

El aprendizaje adaptativo de los estudiantes de un Grado de nueva creación: Análisis de su actividad en el Campus Virtual-UB

La docencia presencial de la Univ. Barcelona se apoya en su Campus virtual. Para promover el aprendizaje adaptativo, hemos analizado los Recursos/Actividades (número, tipo y frecuencia de uso) de 3 cohortes del Grado de Ciencias del Mar (30 Informes de actividad en total y 10 Registros de uso seleccionados). Predominan los Recursos (87%), pero se interactúa más en las Actividades. El análisis de los Registros ha permitido relacionar los resultados con el rendimiento, género u opcionalidad

Grup d'Innovació Docent en Fisiologia (GrInDoFi)

Podeu consultar la Setena trobada de professorat de Ciències de la Salut completa a: http://hdl.handle.net/2445/4335

Blood rheology adjustments in rats after a program of intermittent exposure to hypobaric hypoxia

Esteva, Santiago, Pere Panisello, Joan Ramon Torrella, Teresa Pagés, and Ginés Viscor. Blood rheology adjustments in rats after a program of intermittent exposure to hypobaric hypoxia. High Alt. Med. Biol. 10:275-281, 2009. Intermittent hypobaric hypoxia (IHH) exposure induces a rise in hemoglobin concentration and an increase in erythrocyte mass in both rats and humans. Although this response increases blood oxygen transport capacity, paradoxically, it could impair blood flow and gas exchange because of the blood viscosity alterations associated with the rising hematocrit. In the present study, male rats were subjected to an IHH program consisting of a daily 4-h session for 5 days/week until they had completed 22 days of hypoxia exposure in a hypobaric chamber at a simulated altitude of 5000 m. Blood samples were taken at the end of the exposure period (H) and at 20 (P20) and 40 (P40) days after the end of the program and were compared to control (C) maintained at sea- level pressure. Apparent blood viscosity (ηa) and plasma viscosity (ηp) were measured in a cone-plate microviscometer. Although the hematocrit significantly increased in the H group, blood apparent viscosity did not differ among groups, ranging from 7.67 to 6.57 mPa sec at a shear rate of 90 sec−1. Relative blood viscosity showed a clear increase (about 27%) in H rats, mainly due to the significant decrease in plasma viscosity. This finding could be interpreted as a compensatory response, which reduced the effect of increased erythrocyte mass volume on whole-blood viscosity. Oxygen delivery index and blood oxygen potential transport capacity remained unchanged in all groups. These data indicate that the IHH program has a deep but transitory effect on red cell parameters and a moderate effect on blood rheological behavior