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1,685 result(s) for "Calderon, D"
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Oxidative stress and diabetic retinopathy: development and treatment
Diabetic retinopathy (DR) is the most common microvascular complication in diabetic patients and one of the main causes of acquired blindness in the world. From the 90s until date, the incidence of this complication has increased. Reactive oxygen species (ROS) is a free radical with impaired electron that usually participates in the redox mechanisms of some body molecules such as enzymes, proteins, and so on. In normal biological conditions, ROS is maintained in equilibrium, however its overproduction can lead to biological process called oxidative stress and this is considered the main pathogenesis of DR. The retina is susceptible to ROS because of high-energy demands and exposure to light. When the balance is broken, ROS produces retinal cell injury by interacting with the cellular components. This article describes the possible role of oxidative stress in the development of DR and proposes some treatment options based on its stages. The review of the topic shows that blindness caused by DR can be avoided by early detection and timely treatment.
The neural substrates of rapid-onset Dystonia-Parkinsonism
The authors use a mouse model of rapid-onset dystonia-Parkinsonism to show that an adverse interaction between the cerebellum and basal ganglia can account for the symptoms in this condition. Aberrant cerebellar activity alters basal ganglia function via a di-synaptic thalamic pathway, causing dystonia. Although dystonias are a common group of movement disorders, the mechanisms by which brain dysfunction results in dystonia are not understood. Rapid-onset Dystonia-Parkinsonism (RDP) is a hereditary dystonia caused by mutations in the ATP1A3 gene. Affected individuals can be free of symptoms for years, but rapidly develop persistent dystonia and Parkinsonism-like symptoms after a stressful experience. Using a mouse model, we found that an adverse interaction between the cerebellum and basal ganglia can account for the symptoms of these individuals. The primary instigator of dystonia was the cerebellum, whose aberrant activity altered basal ganglia function, which in turn caused dystonia. This adverse interaction between the cerebellum and basal ganglia was mediated through a di-synaptic thalamic pathway that, when severed, alleviated dystonia. Our results provide a unifying hypothesis for the involvement of cerebellum and basal ganglia in the generation of dystonia and suggest therapeutic strategies for the treatment of RDP.
Activating an anterior nucleus gigantocellularis subpopulation triggers emergence from pharmacologically-induced coma in rodents
Multiple areas within the reticular activating system (RAS) can hasten awakening from sleep or light planes of anesthesia. However, stimulation in individual sites has shown limited recovery from deep global suppression of brain activity, such as coma. Here we identify a subset of RAS neurons within the anterior portion of nucleus gigantocellularis (aNGC) capable of producing a high degree of awakening represented by a broad high frequency cortical reactivation associated with organized movements and behavioral reactivity to the environment from two different models of deep pharmacologically-induced coma (PIC): isoflurane (1.25%–1.5%) and induced hypoglycemic coma. Activating aNGC neurons triggered awakening by recruiting cholinergic, noradrenergic, and glutamatergic arousal pathways. In summary, we identify an evolutionarily conserved population of RAS neurons, which broadly restore cerebral cortical activation and motor behavior in rodents through the coordinated activation of multiple arousal-promoting circuits. The reticular activating system (RAS) of the brainstem regulates wakefulness, and stimulation of RAS areas can reverse effects of anaesthesia. Here, the authors show that stimulation of a particular RAS area, the anterior portion of nucleus gigantocellularis, can produce arousal from deep coma.
Research and prospects of CNC lathe
With the development of the manufacturing industry and the continuous progress of science and technology, as one of the core equipment of the high-end manufacturing industry, CNC lathe is also developed and improved. After searching a large amount of literature, through the elaboration of the current domestic and foreign research institutions for the CNC lathe research history, development level and development status, comparative analysis of different types of CNC lathe structure, characteristics and applications, concluded that the CNC lathe is the best choice for the current rotary parts machining manufacturing tools. On this basis, it analyzes and summarizes the tool path planning, cutting process optimization, high-speed cutting technology and other key technical issues to be solved in the future development of CNC lathe, and finally looks forward to the development trend of CNC lathe, in order to provide references for related research.
Preliminary investigation of use of flexible folding wing tips for static and dynamic load alleviation
A recent consideration in aircraft design is the use of folding wing-tips with the aim of enabling higher aspect ratio aircraft with less induced drag while also meeting airport gate limitations. This study investigates the effect of exploiting folding wing-tips in flight as a device to reduce both static and dynamic loads. A representative civil jet aircraft aeroelastic model was used to explore the effect of introducing a wing-tip device, connected to the wings with an elastic hinge, on the load behaviour. For the dynamic cases, vertical discrete gusts and continuous turbulence were considered. The effects of hinge orientation, stiffness, damping and wing-tip weight on the static and dynamic response were investigated. It was found that significant reductions in both the static and dynamic loads were possible. For the case considered, a 25% increase in span using folding wing-tips resulted in almost no increase in loads.
Research on Ultrasonic Nondestructive Testing Algorithm for Metal Materials
With the continuous development of science and technology, metal castings are widely used in aerospace, oil exploitation and other fields, and the safety and availability of casting quality has become a hot issue in current research. Ultrasonic nondestructive testing has good penetration and directivity, but nonstationary ultrasonic signals will be formed in the process of flaw detection, which has a certain impact on the extraction of effective information. Therefore, by processing and analyzing ultrasonic signals, this paper uses wavelet transform and empirical mode decomposition to make a comparative study. It is found that the wavelet transform denoising algorithm still has distortion after processing the noisy signal. Empirical mode decomposition is based on the signal itself, which has strong adaptability and better performance. Moreover, the improved threshold function has higher accuracy in signal processing, and the distortion degree of waveform is reduced, which is more suitable for noise reduction of metal echo signal, and can meet the requirements of engineering applications.
Parent and Friend Relationship Quality and Links to Trajectories of Loneliness During the First Year of College
Beginning college involves changes that can increase one’s vulnerability to loneliness and associated negative outcomes. Parent and friend relationships are potential protective factors against loneliness given their positive association with adjustment. The present longitudinal study, with data collection at baseline, 1 month, and 2 months later, assessed the comparative effects of self-reported parent and friend relationship quality on loneliness in first-year college students (N = 101; 80 female, Mage = 18.36). At baseline, parent and friend relationship quality were negatively associated with loneliness. Longitudinal data revealed that friend relationship quality interacted with time, such that its effects on loneliness attenuated over the course of 2 months. By contrast, parent relationship quality continued to predict lower loneliness 2 months post-baseline. These results highlight the importance of close relationships and suggest that targeting relationship quality could be effective in helping youth transition to college.
Dual Enhancement of Optoelectronic and Mechanical Performance in Perovskite Solar Cells Enabled by Nanoplate-Structured FTO Interfaces
Perovskite solar cells (PSCs) rarely report, on a single-device platform, concurrent gains in optoelectronic efficiency and buried-interface mechanical robustness—two prerequisites for flexible and roll-to-roll (R2R) integration. We engineered a nanoplate-structured fluorine-doped tin oxide (NP-FTO) front electrode that couples light management with three-dimensional interfacial anchoring, and we quantified both photovoltaic (PV) and nanomechanical metrics on the same device stack. Relative to planar FTO, the NP-FTO PSCs achieved PCE of up to 25.65%, with simultaneous improvements in Voc (to 1.196 V), Jsc (up to 26.35 mA cm−2), and FF (to 82.65%). Nanoindentation revealed a ~28% increase in reduced modulus and >70% higher hardness, accompanied by a ~32% reduction in maximum indentation depth, indicating enhanced load-bearing capacity consistent with the observed FF gains. The low-temperature, solution-compatible NP-FTO interface is amenable to R2R manufacturing and flexible substrates, offering a unified route to bridge high PCE with reinforced interfacial mechanics toward integration-ready perovskite modules.
Silencing of RpATG8 impairs the biogenesis of maternal autophagosomes in vitellogenic oocytes, but does not interrupt follicular atresia in the insect vector Rhodnius prolixus
Follicular atresia is the mechanism by which the oocyte contents are degraded during oogenesis in response to stress conditions, allowing the energetic resources stored in the developing oocytes to be reallocated to optimize female fitness. Autophagy is a conserved intracellular degradation pathway where double-membrane vesicles are formed around target organelles leading to their degradation after lysosome fusion. The autophagy-related protein 8 (ATG8) is conjugated to the autophagic membrane and has a key role in the elongation and closure of the autophagosome. Here we identified one single isoform of ATG8 in the genome of the insect vector of Chagas Disease Rhodnius prolixus (RpATG8) and found that it is highly expressed in the ovary during vitellogenesis. Accordingly, autophagosomes were detected in the vitellogenic oocytes, as seen by immunoblotting and electron microscopy. To test if autophagosomes were important for follicular atresia, we silenced RpATG8 and elicited atresia in vitellogenic females by Zymosan-A injections. We found that silenced females were still able to trigger the same levels of follicle atresia, and that their atretic oocytes presented a characteristic morphology, with accumulated brown aggregates. Regardless of the difference in morphology, RpATG8-silenced atretic oocytes presented the same levels of protein, TAG and PolyP, as detected in control atretic oocytes, as well as the same levels of acidification of the yolk organelles. Because follicular atresia has the ultimate goal of restoring female fitness, we tested if RpATG8-silenced atresia would result in female physiology and behavior changes. Under insectarium conditions, we found that atresia-induced control and RpATG8-silenced females present no changes in blood meal digestion, survival, oviposition, TAG content in the fat body, haemolymph amino acid levels and overall locomotor activity. Altogether, we found that autophagosomes are formed during oogenesis and that the silencing of RpATG8 impairs autophagosome biogenesis in the oocytes. Nevertheless, regarding major macromolecule degradation and adaptations to the fitness costs imposed by triggering an immune response, we found that autophagic organelles are not essential for follicle atresia in R. prolixus.
Design and Research of Multi Segment Exoskeleton Reconfigurable Soft Finger Actuator
The growing number of patients with hand dysfunction caused by conditions such as stroke has led to increasing demand for soft finger rehabilitation actuators. However, existing devices of this type often face issues such as irregular deformation, insufficient driving force, the inability to achieve segmented control, and poor rigidity retention. A multi-segment exoskeleton design is proposed, which achieves a functional separation between actuation and load-bearing. Utilizing the principle of virtual work and the Yeoh constitutive model, derive the pressure-to-angle transfer function to facilitate the establishment of the overall equation of motion. The finite element analysis and experimental tests conducted in this study prove that the design prevents irregular deformation, enables segmented control, and maintains high rigidity. Through physical testing, a maximum bending angle of 338.7° and a maximum driving force of 11.50 N were achieved, which is 25.27% higher than the 9.18 N force found in existing studies. The multi-segment reconfigurable soft finger exoskeleton actuator proposed in this study demonstrates significant advantages over conventional devices, with its enhanced bending range and force output facilitating patients' performance of daily grasping tasks. The segmented control capability enables personalized rehabilitation training targeting specific finger joints. This innovation holds substantial promise for improving hand function recovery in stroke patients.