Well-being variations on students of health sciences related to their learning opportunities, resources, and daily activities in an online and on-crisis context: a survey-based study.

BACKGROUND: Universities' training process intensely relies on face-to-face education. The COVID-19 pandemic interrupted it and forced them to reinvent their process online. But this crisis seems not to be the last we will face, and we take it as a lesson to prepare for future crises. These critical contexts are especially challenging because they imply changing teaching strategies, and students may not have the technology access or the living conditions to connect as they need. They also lived through a pandemic where the virus and the life changes added stress to their learning process and threatened their well-being. So, this study aims to analyze how well-being variations reported by Health sciences students relate to their learning opportunities, access conditions, and daily activities. METHOD: We surveyed 910 Health sciences students from six different Chilean universities at the end of the first semester of 2020, the first in pandemic conditions. Respondents answered online questionnaires about 1) Remote teaching activities, 2) Learning resources availability, 3) Daily life activities, and 4) Well-being changes. We performed descriptive analysis and Structural Equation Modelling. RESULTS: Live videoconference classes were the most frequent teaching activity; only a third of the students had quiet spaces to study online, and most had to housekeep daily. More than two third reported some well-being deterioration. The structural equation model showed a good fit. CONCLUSION: Results show an online learning scenario that tries to emulate traditional learning focusing on expositive strategies. Most students reported that their well-being deteriorated during the semester, but tutorials, workplace availability, and social support were protective factors.

Satisfaction with remote teaching during the first semester of the COVID-19 crisis: Psychometric properties of a scale for health students.

INTRODUCTION: Due to the health crisis caused by the COVID-19 pandemic, 220 million college students in the world had to halt face-to-face teaching and migrate to what has been called Emergency Remote Teaching, using virtual media, but without adequate preparation. The way this has impacted the student body and its satisfaction with the training process is unknown and there are no instruments backed by specific validity and reliability studies for this teaching context. This is why this study aims to analyze the psychometric properties of the Remote Teaching Satisfaction Scale applied to Chilean health sciences students. METHOD: Quantitative study by means of surveys. We surveyed 1,006 health careers undergraduates chosen by convenience sampling. They came from six Chilean universities, located over a distance of 3,020 kilometers and followed 7 different careers. Women comprised the 78.53%. They answered the Remote Teaching Satisfaction Scale online to evaluate their perception of the first Emergency Remote Teaching term in 2020. RESULTS: A descriptive analysis of the items showed a moderate to positive evaluation of the teaching. The Confirmatory Factorial Analysis showed an adequate adjustment of the theoretical four factors model to the data obtained (CFI = 0.959; TLI = 0.953; RMSEA = 0.040). Correlations among factors oscillated from r = 0.21 to r = 0.69. The measurement invariance analysis supported the Configural, Metric and a partial Scalar model. Differences were found in three of the four factors when comparing the first-year students with those of later years. Finally, the Cronbach's α and McDonald's ω coefficients were over 0.70. DISCUSSION: The results display initial psychometric evidence supporting the validity and reliability of the Remote Teaching Satisfaction Scale to assess academic satisfaction in Chilean health careers students. Likewise, it is seen that first-year students show higher satisfaction levels about the implemented teaching.

Evaluation of a Dielectric-Only Transmitarray for Generating Multi-Focusing Near-Field Spots Using a Cluster of Feeds in the Ka-Band.

A transmitarray antenna is evaluated to generate a multi-focusing spot area in the Fresnel region of the antenna in the Ka-band. The antenna is designed to focus the radiated field at a certain point using a central feeding configuration. The number of feeds is increased to create as many focusing spots as feeds. The feeds are placed along an arc defined in the principal planes of the transmitarray, radiating independent near-field spots and providing a solution with a wide-angle spot scanning without an antenna displacement and a high isolation between feeds. To validate this concept, a transmitarray based on dielectric-only cells is designed and simulated under full-wave conditions. Then, this design is manufactured using a 3D printing technique, and the prototype is measured in a planar acquisition range. Measurements are performed for different feed positions in order to validate the multi-focusing capability of the antenna. Measurements and simulations show a high agreement and validate the proposed design technique.

Reflectarray antennas: a smart solution for new generation satellite mega-constellations in space communications.

One of the most ambitious projects in communications in recent years is the development of the so-called satellite mega-constellations. Comprised of hundreds or thousands of small and low-cost satellites, they aim to provide internet services in places without existing broadband access. For the antenna subsystem, reflectarrays have been proposed as a cheap solution due to their low profile and manufacturing costs, while still providing good performance. This paper presents a full design of a reflectarray antenna for mega-constellation satellites with a shaped-beam isoflux pattern for constant power flux in the surface of the Earth. A unit cell consisting of two stacked rectangular microstrip patches backed by a ground plane is employed, providing more than 360° of phase-shift. The generalized intersection approach optimization algorithm is employed to synthesize the required isoflux pattern in a 2 GHz bandwidth in Ku-band. To that purpose, a full-wave electromagnetic analysis is employed for the wideband design. The optimized reflectarray layout complies with the specifications of the isoflux pattern in the frequency band 16 GHz-18 GHz, demonstrating the capabilities of this type of antenna to provide a low-cost, low-profile solution for the user beam segment, including different types of shaped beams.

Impact of experimental haemodilution on platelet function, thrombin generation and clot firmness: effects of different coagulation factor concentrates.

BACKGROUND: Haemodilution during resuscitation after massive haemorrhage may worsen the coagulopathy and perpetuate bleeding. MATERIALS AND METHODS: Blood samples from healthy donors were diluted (30 and-60%) using crystalloids (saline, Ringer's lactate, Plasmalyte(TM)) or colloids (6% hydroxyethylstarch [HES130/0.4], 5% human albumin, and gelatin). The effects of haemodilution on platelet adhesion (Impact R), thrombin generation (TG), and thromboelastometry (TEM) parameters were analysed as were the effects of fibrinogen, prothrombin complex concentrates (PCC), activated recombinant factor VII (FVIIa), and cryoprecipates on haemodilution. RESULTS: Platelet interactions was already significantly reduced at 30% haemodilution. Platelet reactivity was not improved by addition of any of the concentrates tested. A decrease in TG and marked alterations of TEM parameters were noted at 60% haemodilution. HES130/0.4 was the expander with the most deleterious action. TG was significantly enhanced by PCC whereas rFVIIa only caused a mild acceleration of TG initiation. Fibrinogen restored the alterations of TEM parameters caused by haemodilution including those caused by HES 130/0.4. Cryoprecipitates significantly improved the alterations caused by haemodilution on TG and TEM parameters; the effects on TG disappeared after ultracentrifugation of the cryoprecipitates. DISCUSSION: The haemostatic alterations caused by haemodilution are multifactorial and affect both blood cells and coagulation. In our in vitro approach, HES 130/0.4 had the most deleterious effect on haemostasis parameters. Coagulation factor concentrates did not improve platelet interactions in the Impact R, but did have favourable effects on coagulation parameters measured by TG and TEM. Fibrinogen notably improved TEM parameters without increasing thrombin generation, suggesting that this concentrate may help to preserve blood clotting abilities during haemodilution without enhancing the prothrombotic risk.

Assessment of platelet function in horses: ultrastructure, flow cytometry, and perfusion techniques.

We studied equine platelet function and activation using ultrastructural examination, flow cytometry, and perfusion. The main aim of the study was to evaluate hemostatic mechanisms in horses using these techniques. Ultrastructural observations were done on resting and activated platelets. Flow cytometry was used to evaluate binding of antibodies to major platelet glycoproteins (GPIIb-IIIa, GPIV, and GPIb) and activation-dependent antigens (P-selectin and lysosomal integral membrane protein [LIMP]). Perfusion techniques were used to evaluate the interaction between platelets and damaged subendothelium. Aggregation experiments were done to identify the best agonists for flow cytometry. Ultrastructural observations confirmed that equine platelets lack a developed open canalicular system and that release of granule contents occurs by fusion of adjacent granule membranes that ultimately connect with external membranes. Flow cytometry identified a 2-fold increase in binding of antibodies against GPIIb-IIIa and GPIV after activation. Binding of antibodies against P-selectin and LIMP increased from 2.12 and 1.74% to 15.5 and 11.6%, respectively, in response to thrombin and to 21.86 and 10.50%, respectively, in response to collagen. Annexin V binding increased moderately after activation. Perfusion experiments with citrated blood indicated that equine platelets react more strongly to subendothelium than do human platelets. When blood was anticoagulated with low molecular weight heparin, a marked impairment of platelet interactions was observed. In conclusion, although some differences were observed between human and equine platelet function, some techniques currently used to assess human platelet function may be useful to assess equine platelets.

Hemostatic effect of activated recombinant factor VII (rFVIIa) in liver disease: studies in an in vitro model.

BACKGROUND/AIMS: There is clinical evidence for the efficacy of activated recombinant factor VII (rFVIIa) in patients with cirrhosis. The exact mechanism of action of rFVIIa in this clinical condition is unknown. We have explored effects of rFVIIa on hemostasis in cirrhotic patients using an in vitro perfusion technique. METHODS: Blood samples were drawn from control donors or from 11 patients previously diagnosed with cirrhosis (seven Child-Pugh B and four Child-Pugh C) and anticoagulated with low molecular weight heparin. rFVIIa was added to blood samples at therapeutic concentrations (0.5 or 1 microg/ml of plasma) and blood was recirculated through annular chambers containing damaged vascular segments. Presence of platelets and fibrin on the subendothelium were morphometrically quantified. RESULTS: Cirrhotic patients showed a diminished platelet interaction with the subendothelium compared to healthy donors (17.3% (9.28-28.88%) vs. 26.16% (19.96-54.5%), P<0.05). After addition of rFVIIa to cirrhotic samples, no differences in platelet covered surface were observed. However, fibrin formation was significantly improved after the addition of rFVIIa (from 51.81% (3.02-86.68%) to 86.94% (30.03-93.18%) and 89.05% (45.65-93.84%), respectively, P<0.05). CONCLUSIONS: Our data confirm a defective interaction of platelets with the subendothelium in cirrhotic patients. rFVIIa improved local fibrin formation at damaged sites and this mechanism could explain the beneficial action of rFVIIa in cirrhotic patients.

Increased local procoagulant action: a mechanism contributing to the favorable hemostatic effect of recombinant FVIIa in PLT disorders.

BACKGROUND: Recombinant FVIIa (rFVIIa) has been shown to improve hemostasis in patients with thrombocytopenia and to prevent or control bleeding episodes in patients with inherited deficiencies of major PLT glycoproteins, but the mechanism of action is not well understood. STUDY DESIGN AND METHODS: Effects of rFVIIa on hemostasis were explored with an in vitro perfusion technique. Blood samples, from healthy donors or from patients with congenital defects of PLT glycoprotein IIb-IIIa (GPIIb-IIIa), were anticoagulated with low-molecular-weight heparin. Experimental thrombocytopenia (<6000 PLTs/microL) was induced by a filtration procedure. rFVIIa was added to blood samples at therapeutic concentrations. A severe GPIIb-IIIa impairment was also induced by exposure of normal blood samples to a specific antibody. Perfusion studies were performed through annular chambers containing damaged vascular segments. The presence of fibrin and PLTs on the perfused subendothelium was morphometrically quantified. RESULTS: Under conditions of experimental thrombocytopenia, addition of rFVIIa enhanced fibrin formation in a dose-dependent manner (p < 0.05). Improvements in local fibrin generation and partial restoration of PLT interactions were also observed after incubation of blood from patients with Glanzmann's thrombasthenia with rFVIIa at 5 microg per mL (180 microg/kg). Similar improvements were observed in blood samples incubated with antibodies to GPIIb-IIIa. rFVIIa in whole normal blood also enhanced fibrin formation but PLT deposition was unaffected. Evaluation of prothrombin fragments 1 and 2 in the perfusates confirmed that rFVIIa increased thrombin generation in all cases. CONCLUSION: Our data indicate that rFVIIa promotes a procoagulant activity at sites of vascular damage. This mechanism could explain the beneficial hemostatic effect of rFVIIa in patients with thrombocytopenia or with Glanzmann's thrombasthenia.

Diseño y realización de prótesis mandibulares individuales apoyado por estudio de tomografía axial computada / Individual design for mandibular reconstruction with ct scan assistance

La presente investigación fue de tipo Descriptivo y Aplicada cuyo objetivo fue el de obtener, apoyado en estudio tomográfico, un diseño individual para reconstrucción mandibular. Dicho diseño nos permite realizar una reposición con las mismas características del segmento mandibular que se va a resecar en el acto quirúrgico. Se escogió una muestra de cinco pacientes que presentaron patología mandibular y a los cuales se les realizó estudio tomográfico axial. Esta muestra fue intencional y de conveniencia por constituir un estudio piloto. La investigación se llevo a cabo en el Servicio de Cabeza y Cuello del Instituto Oncológico "Dr. Miguel Pérez Carreño", Bárbula, Edo. Carabobo, en el período comprendido entre enero de 2000-2001. Se logró obtener un diseño pre-definido de mandíbula, el cual es idéntico o casi idéntico al segmento que se pretende retirar en el acto quirúrgico, lo cual nos permite planificar la mejor opción reconstructiva para cada paciente con el fin de lograr una reposición funcional y estética a los pacientes que son sometidos a este tipo de cirugía