Heart Rate Variability Control Using a Biofeedback and Wearable System.

Heart rate variability is an important physiological parameter in medicine. This parameter is used as an indicator of physiological and psychological well-being and even of certain pathologies. Research on biofeedback integrates the fields of biological application (physiological behavior), system modeling, and automated control. This study proposes a new method for modeling and controlling heart rate variability as heart rate acceleration, a model expressed in the frequency domain. The model is obtained from excitation and response signals from heart rate variability, which through the instrumental variables method and the minimization of a cost function delivers a transfer function that represents the physiological phenomenon. This study also proposes the design of an adaptive controller using the reference model. The controller controls heart rate variability based on the light actuators designed here, generating a conditioned reflex that allows individuals to self-regulate their state through biofeedback, synchronizing this action to homeostasis. Modeling is conducted in a target population of middle-aged men who work as firefighters and forest firefighters. This study validates the proposed model, as well as the design of the controllers and actuators, through a simple experiment based on indoor cycling. This experiment has different segments, namely leaving inertia, non-controlled segment, and actively controlled segment.

Multipolar analysis of the second harmonic generated by dielectric particles.

We studied the second harmonic generation (SHG) by two-dimensional dielectric particles made of a centrosymmetric high-index material. The calculated scattered fields at the fundamental and harmonic frequencies are decomposed on a multipolar basis, allowing the evaluation of the relative strengths of the multipolar resonances excited at the particle. With these tools, we studied the strength of the multipoles that produce the second harmonic field and the role played by those excited at the fundamental frequency.

Influence of finite conductivity on the excitation of phase resonances in metallic surfaces with cavities of circular cross sections.

Phase resonances have been investigated in the last few years, not only because of their striking features, such as extremely high quality factor and huge enhancement of the electromagnetic field inside cavities/grooves, but also for their promising applications. However, taking into account that these resonances are more efficiently excited in highly conducting structures, most of the studies have been devoted to explore this phenomenon at wavelengths in the infrared or larger, using different approaches for the boundary conditions. In this paper, we investigate the validity of the perfect conductor approximation and the surface impedance boundary condition to appropriately represent the electromagnetic response of a metallic surface comprising a finite number of subwavelength cavities of circular cross sections. Far- and near-field plots are shown and analyzed in order to investigate the validity ranges and discuss to what extent phase resonances can be excited at shorter wavelengths in these structures.

Phase resonances induced by a subwavelength particle near a surface with two cavities.

It is well known that finite groove gratings with subwavelength features exhibit phase resonances, which are associated with a particular distribution of the magnetic field phase within the cavities and are characterized by a significant enhancement of the internal field. For a flat surface with identical grooves under symmetrical conditions of incidence, it was shown that a minimum of three cavities is required to excite a phase resonance. In this paper we show that by approaching a particle to the surface, this requirement is removed and the particle enables the excitation of phase resonances even in a system of two identical cavities under normal incidence. The influence of the position and the radius of the particle in the reflected far field response, as well as in the near and internal field, is analyzed. The possibility of exciting phase resonances in this system opens up new means for the design of sensing devices.

Bases fisiopatológicas para una clasificación de la neuropatía diabética / A new physiopathological classification of diabetic neuropathy

Nowadays, Diabetic Neuropathy (DN) is considered the most common cause of peripheral neuropathy in clinical practice. It can affect sensitive, motor or autonomic nerve fibers, with symmetric, asymmetric, acute or chronic presentations. Due to this variability, with multiple physiopathologic mechanisms involved, a complex clinical classification has been used until recently. The aim of this review is to present a new classification of diabetic neuropathy, based on its physiopathology. It is divided in metabolic microvascular and hypoxic, autoimmune and inflammatory, compressive, secondary to complications ofdiabetes and related to treatment. It must be understood that DN is notjust a functional disease, but a complication of diabetes with molecular and pathological substrates caused by hyperglycemia. Therefore, normalization of blood glucose is a fundamental step towards the successful prevention and treatment of DN.

[A new physiopathological classification of diabetic neuropathy]. / Bases fisiopatológicas para una clasificación de la neuropatía diabética.

Nowadays, Diabetic Neuropathy (DN) is considered the most common cause of peripheral neuropathy in clinical practice. It can affect sensitive, motor or autonomic nerve fibers, with symmetric, asymmetric, acute or chronic presentations. Due to this variability, with multiple physiopathologic mechanisms involved, a complex clinical classification has been used until recently. The aim of this review is to present a new classification of diabetic neuropathy, based on its physiopathology. It is divided in metabolic microvascular and hypoxic, autoimmune and inflammatory, compressive, secondary to complications of diabetes and related to treatment. It must be understood that DN is not just a functional disease, but a complication of diabetes with molecular and pathological substrates caused by hyperglycemia. Therefore, normalization of blood glucose is a fundamental step towards the successful prevention and treatment of DN.

Gestational diabetes and pre-pregnancy overweight: possible factors involved in newborn macrosomia.

AIM: Good glycemic control in gestational diabetes mellitus (GDM) seems not to be enough to prevent macrosomia (large-for-gestational-age newborns). In GDM pregnancies we studied the effects of glycemic control (as glycosylated hemoglobin [HbA1c]), pre-pregnancy body mass index (PP-BMI) and gestational weight gain per week (GWG-W) on the frequency of macrosomia. METHODS: We studied 251 GDM pregnancies, divided into two groups: PP-BMI<25.0kg/m(2) (the non-overweight group; n=125), and PP-BMI≥25.0kg/m(2) (the overweight group; n=126). A newborn weight Z-score>1.28 was considered large-for-gestational-age. Statistical analysis was carried out using the Student's t-test and χ(2) -test, receiver-operator characteristic curves and linear and binary logistic regressions. RESULTS: Prevalence of macrosomia was 14.9% among GDM (n=202/251, 88.4%) with good glycemic control (mean HbA1c<6.0%), and 28.1% in those with mean HbA1c≥6.0% (n=49/251, P<0.025). Macrosomia rates were 10.4% in the non-overweight group and 24.6% in the overweight group (P=0.00308), notwithstanding both having similar mean HbA1c (5.48±0.065 and 5.65±0.079%, P=0.269), and similar GWG-W (0.292±0.017 and 0.240±0.021kg/week, P=0.077). Binary logistic regressions showed that PP-BMI (P=0.012) and mean HbA1c (P=0.048), but not GWG-W (P=0.477), explained macrosomia. CONCLUSIONS: Good glycemic control in GDM patients was not enough to reduce macrosomia to acceptable limits (<10% of newborns). PP-BMI and mean HbA1c (but not GWG-W) were significant predictors of macrosomia. Thus, without ceasing in our efforts to improve glycemic control during GDM pregnancies, patients with overweight/obesity need to be treated prior to becoming pregnant.

Detection of Trypanosoma cruzi in untreated chronic chagasic patients is improved by using three parasitological methods simultaneously.

OBJECTIVES: This study compared three parasitological methods applied simultaneously in individuals with untreated chronic Chagas' disease in order to determine their individual and combined performances. METHODS: From a total of 100 chronic chagasic patients from endemic areas of Chile, with informed consent, we extracted 2 mL of peripheral venous blood for PCR (PCR-B) and applied two xenodiagnosis (XD) boxes with seven uninfected Triatoma infestans nymphs each for microscopic examination and PCR of faecal samples of the triatomines fed on each patient (PCR-XD). The PCR-B and PCR-XD reactions were performed with oligonucleotides 121 and 122, which anneal to the four constant regions of the minicircles of Trypanosoma cruzi kinetoplasts. The 330 bp PCR product was analysed by electrophoresis in a 2% agarose gel and visualized by staining with ethidium bromide. RESULTS: PCR-B detected T. cruzi in 58% of the cases, while PCR-XD proved to be more sensitive than XD (67% versus 14%, respectively) (P = 0.0001). There was no difference between the detection power of PCR-B and PCR-XD (P = 0.222). The percentage detected as positive was much greater when the three tests were considered (84%) (P = 0.00001). CONCLUSIONS: The simultaneous application of more than one technique for the parasitological diagnosis of Chagas' disease in untreated individuals increases the possibility of detection of T. cruzi.

Anomalous reflection in a metallic plate with subwavelength grooves of circular cross section.

Resonant features in the response of finite arrays of rectangular grooves ruled on a metallic plate have been reported in connection with the excitation of phase resonances. These anomalies are generated by a particular arrangement of the magnetic field phases inside the subwavelength grooves when the structure is illuminated by a p-polarized electromagnetic wave. We show that this kind of resonance is also present for grooves of circular cross section and appear as sharp peaks in the specular response, the number of which increases with the number of grooves in the structure. A significant intensification of the field within the grooves is also found for these particular phase configurations. The dependence of the response on the geometrical parameters of the structure is analyzed in detail, in order to consider these structures for potential applications such as frequency selectors and polarizers.

On the transmission of diffuse light through thick slits.

We study the transmission of diffuse light through thick slits. For perfectly conducting slits and in-plane s-polarized illumination, the transmittance curves present a staircaselike behavior as a function of the aperture width, where the steps mark the appearance of new propagation modes. In contrast, with p-polarized illumination the transmittance increases linearly with the aperture width, with only some perturbations in the positions that correspond to the appearance of new modes. Out-of-plane incidence and more realistic assumptions about the slit, such as finite conductivity and roughness, are also discussed.

Cytochemical and biochemical demonstration of an ATPase in membranes of human peroxisomes.

We demonstrated a neutral Mg-ATPase activity in human peroxisomal membranes. To establish the precise experimental conditions for detection of this ATPase, both cytochemical and biochemical characterizations were first carried out in liver peroxisomes from control and cipofibrate-treated rats. The results demonstrated an Mg-ATPase reaction in both normal and proliferated peroxisomes. The nucleotidase activity, with marked preference for ATP, was sensitive to the inhibitors N-ethylmaleimide and 7-chloro-4-nitro-benzo-2-oxadiazole (NBDCl). An ultrastructural cytochemical analysis was developed to evaluate the peroxisomal localization, which localized the reaction product to the peroxisomal membrane. These characteristics can help to differentiate the peroxisomal ATPase from the activity found in mitochondria and endoplasmic reticulum. The conditions established for detecting the rat peroxisomal ATPase were then applied to human peroxisomes isolated from liver and skin fibroblasts in culture. A similar Mg-ATPase activity was readily shown, both cytochemically and biochemically, in the membranes of human peroxisomes. These results, together with previous evidence, strongly support the presence of a specific ATPase in the human peroxisomal membrane. This ATPase may play a crucial role in peroxisome biogenesis.

Usos clínicos de neurolépticos orales y de depósito / Clinical uses of oral and depot neuroleptics

Se efectúa una revisión de las características farmacológicas y del uso clínico de los neurolépticos orales y de depósito más utilizados. Se analizan las principales causas de fracaso terapéutico, enfatizando los factores de riesgo de las complicaciones de mayor importancia y en particular de las diskinesias tardías y del síndrome neuroléptico maligno