6,661 research outputs found

    Role of Cerebellar Interpositus Nucleus in the Genesis and Control of Reflex and Conditioned Eyelid Responses

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    The role of cerebellar circuits in the acquisition of new motor abilities is still a matter of intensive debate. To establish the contribution of posterior interpositus nucleus (PIN) to the performance and/or acquisition of reflex and classically conditioned responses (CRs) of the eyelid, the effects of microstimulation and/or pharmacological inhibition by muscimol of the nucleus were investigated in conscious cats. Microstimulation of the PIN in naive animals evoked ramp-like eyelid responses with a wavy appearance, without producing any noticeable plastic functional change in the cerebellar and brainstem circuits involved. Muscimol microinjections decreased the amplitude of reflex eyeblinks evoked by air puffs, both when presented alone or when paired with a tone as conditioned stimulus (CS). In half-conditioned animals, muscimol injections also decreased the amplitude and damped the typical wavy profile of CRs, whereas microstimulation of the same sites increased both parameters. However, neither muscimol injections nor microstimulation modified the expected percentage of CRs, suggesting a major role of the PIN in the performance of eyelid responses rather than in the learning process. Moreover, the simultaneous presentation of CS and microstimulation in well trained animals evoked CRs similar in amplitude to the added value of those evoked by the two stimuli presented separately. In contrast, muscimol-injected animals developed CRs to paired CS and microstimulation presentations, larger than those evoked by the two stimuli when presented alone. It is concluded that the PIN contributes to the enhancement of both reflex and conditioned eyelid responses and to the damping of resonant properties of neuromuscular elements controlling eyelid kinematics

    A Ubiquitous Learning Model for Education and Training Processes Supported by TV Everywhere Platforms

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    Advances in technology and digital convergence, for example Netflix, enable users to view TV and video without time or place restrictions. These advances can be applied in education and training processes to enable ubiquitous learning (u-learning). However, a literature review (of the years 2002 to 2018) on u-learning models yielded scarce information about its implementation, specifically demonstrating a lack of application alternatives that could provide access to TV regardless of place and device. To contribute to this and other challenges in education, the objective of this study is to propose a reference model for u-learning implementation involving cloud-supported TV/video platforms. The model was validated in a university context by a group of experts and applied through a prototype in a real setting with students, and it showed favourable results and improvement in student performance

    Crystal structure of cobalt hydroxide carbonate Co2CO3(OH)(2): density functional theory and X-ray diffraction investigation

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    The cobalt carbonate hydroxide Co2CO3(OH)2 is a technologically important solid which is used as a precursor for the synthesis of cobalt oxides in a wide range of applications. It also has relevance as a potential immobilizer of the toxic element cobalt in the natural environment, but its detailed crystal structure is so far unknown. The structure of Co2CO3(OH)2 has now been investigated using density functional theory (DFT) simulations and powder X-ray diffraction (PXRD) measurements on samples synthesized via deposition from aqueous solution. Two possible monoclinic phases are considered, with closely related but symmetrically different crystal structures, based on those of the minerals malachite [Cu2CO3(OH)2] and rosasite [Cu1.5Zn0.5CO3(OH)2], as well as an orthorhombic phase that can be seen as a common parent structure for the two monoclinic phases, and a triclinic phase with the structure of the mineral kolwezite [Cu1.34Co0.66CO3(OH)2]. The DFT simulations predict that the rosasite-like and malachite-like phases are two different local minima of the potential energy landscape for Co2CO3(OH)2 and are practically degenerate in energy, while the orthorhombic and triclinic structures are unstable and experience barrierless transformations to the malachite phase upon relaxation. The best fit to the PXRD data is obtained using a rosasite model [monoclinic with space group P1121/n and cell parameters a = 3.1408 (4) Å, b = 12.2914 (17) Å, c = 9.3311 (16) Å and γ = 82.299 (16)°]. However, some features of the PXRD pattern are still not well accounted for by this refinement and the residual parameters are relatively poor. The relationship between the rosasite and malachite phases of Co2CO3(OH)2 is discussed and it is shown that they can be seen as polytypes. Based on the similar calculated stabilities of these two polytypes, it is speculated that some level of stacking disorder could account for the poor fit of the PXRD data. The possibility that Co2CO3(OH)2 could crystallize, under different growth conditions, as either rosasite or malachite, or even as a stacking-disordered phase intermediate between the two, requires further investigation

    Responsiveness comparison between a lift-type and drag-type rotor in waves

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    Our recent progress on development of a vertical-axis unidirectional rotary wave energy converter (WEC) is discussed in this work. The WEC features a vertical-axis rotor that preforms unidirectional rotation in waves. The vertical axis arrangement makes the WEC respond well to waves from any direction with no realignment needs. And, the unidirectional behavior of the rotor promises no wave frequency discrimination, which is in comparison to reciprocating WECs that employ the resonant principle and are very frequency-specific. In our earlier proof-of-concept studies, we have successfully demonstrated two types of rotor designs: a lift type employing hydrofoil blades and a drag type using cup blades. In the present work, the two rotor types were further explored experimentally by employing more rotor configurations and blade shapes. The focus was on revealing the rotor responsiveness in simulated waves under a freewheeling condition. The experimental results were compared between a lift-type and drag-type rotor. The comparison provided in-depth understanding on common features of the two rotor types and major differences between them. The yielded research findings will directly guide the development of a prototype vertical-axis unidirectional WEC

    Parameter identification of periodical signals: Application to measurement and analysis of ocean wave forces

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    This article presents an approach based on state observers to identify the parameters of an unknown periodic force exerted on a mechanical system. This approach comprises two stages and can be executed in real time by using only displacement measurements. The first stage goal is the estimation of the coefficients of a Fourier series that approximates the periodic force. From the estimated coefficients, the phase and the amplitude of the signal can be simultaneously computed; and from the estimated force, in a second stage, the frequencies of the signal can be estimated. To perform the tasks at each stage, two state observers were designed. To show the applicability of the proposed approach, the reconstruction of a wave force affecting a marine structure as well as the computation of the amplitude and phase of its spectral components was taken as case of study. The performance of the state observer was examined by means of simulations and off-line tests carried out with experimental data. Such data were obtained by executing laboratory tests and measuring waves in the Caribbean sea

    Radical radiotherapy in epidermoid cancer in the orbitary region: ideal scheme of hypo-fractionation in times of COVID-19: a case report

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    There are adverse events in the patient's environment that impact on therapeutic decisions and become a medical challenge, as is currently the management of cancer patients with radiotherapy, particularly the elderly in times of a COVID-19 pandemic, due the high risk of infection and fatal complications from non-cancer causes. Here we present the case of an 84-year-old woman with voluminous squamous cell cancer in the left orbital region, which caused intense pain, stench, and persistent bleeding. And due to persistence and time, it impacted with deterioration in the patient’s quality of life. In the end, of hypo fractionated radiotherapy management as the only modality, it evolves with a complete clinical response and total palliation of initial symptoms. The reasons for the decision to manage radiotherapy and the excellent clinical results that reinforce the idea of personalized medicine and the importance of evaluating the biopsychosocial environment of the cancer patient will be discussed

    Candida albicans Induces Arginine Biosynthetic Genes in Response to Host-Derived Reactive Oxygen Species

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    The interaction of Candida albicans with phagocytes of the host\u27s innate immune system is highly dynamic, and its outcome directly impacts the progression of infection. While the switch to hyphal growth within the macrophage is the most obvious physiological response, much of the genetic response reflects nutrient starvation: translational repression and induction of alternative carbon metabolism. Changes in amino acid metabolism are not seen, with the striking exception of arginine biosynthesis, which is upregulated in its entirety during coculture with macrophages. Using single-cell reporters, we showed here that arginine biosynthetic genes are induced specifically in phagocytosed cells. This induction is lower in magnitude than during arginine starvation in vitro and is driven not by an arginine deficiency within the phagocyte but instead by exposure to reactive oxygen species (ROS). Curiously, these genes are induced in a narrow window of sublethal ROS concentrations. C. albicans cells phagocytosed by primary macrophages deficient in the gp91phox subunit of the phagocyte oxidase do not express the ARG pathway, indicating that the induction is dependent on the phagocyte oxidative burst. C. albicans arg pathway mutants are retarded in germ tube and hypha formation within macrophages but are not notably more sensitive to ROS. We also find that the ARG pathway is regulated not by the general amino acid control response but by transcriptional regulators similar to the Saccharomyces cerevisiae ArgR complex. In summary, phagocytosis induces this single amino acid biosynthetic pathway in an ROS-dependent manner

    Determinants of Metabolic Health Across Body Mass Index Categories in Central Europe: A Comparison Between Swiss and Czech Populations.

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    Comparisons among countries can help to identify opportunities for the reduction of inequalities in cardiometabolic health. The present cross-sectional analysis and meta-analysis aim to address to what extent obesity traits, socioeconomic, and behavioral factors determine poor metabolic health across body mass index (BMI) categories in two urban population-based samples from Central Europe. Data from the CoLaus (~6,000 participants; Lausanne, Switzerland) and the Kardiovize Brno 2030 (~2,000 participants; Brno, Czech Republic) cohorts. For each cohort, logistic regression analyses were performed to identify the main determinants of poor metabolic health overall and stratified by body mass index (BMI) categories. The results of each cohort were then combined in a meta-analysis. We first observed that waist circumference and body fat mass were associated with metabolic health, especially in non-obese individuals. Moreover, increasing age, being male, having low-medium educational level, abdominal obesity, and high body fat mass were the main determinants of the metabolically unhealthy profile in both cohorts. Meta-analysis stratified by BMI categories confirmed the previous results with slight differences across BMI categories. In fact, increasing age and being male were the main determinants of poor metabolic health independent of obesity status. In contrast, low educational level and current smoking were associated with poor metabolic health only in non-obese individuals. In line, public health strategies against obesity and related comorbidities should aim to improve social conditions and to promote healthy lifestyles before the progression of metabolic disorders
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