1,205 research outputs found
The IAS-MEEG Package: A Flexible Inverse Source Reconstruction Platform for Reconstruction and Visualization of Brain Activity from M/EEG Data
We present a standalone Matlab software platform complete with visualization for the reconstruction of the neural activity in the brain from MEG or EEG data. The underlying inversion combines hierarchical Bayesian models and Krylov subspace iterative least squares solvers. The Bayesian framework of the underlying inversion algorithm allows to account for anatomical information and possible a priori belief about the focality of the reconstruction. The computational efficiency makes the software suitable for the reconstruction of lengthy time series on standard computing equipment. The algorithm requires minimal user provided input parameters, although the user can express the desired focality and accuracy of the solution. The code has been designed so as to favor the parallelization performed automatically by Matlab, according to the resources of the host computer. We demonstrate the flexibility of the platform by reconstructing activity patterns with supports of different sizes from MEG and EEG data. Moreover, we show that the software reconstructs well activity patches located either in the subcortical brain structures or on the cortex. The inverse solver and visualization modules can be used either individually or in combination. We also provide a version of the inverse solver that can be used within Brainstorm toolbox. All the software is available online by Github, including the Brainstorm plugin, with accompanying documentation and test data
Serine hydroxymethyltransferase: origin of substrate specificity
All forms of serine hydroxymethyltransferase, for which a primary structure is known, have five threonine residues near the active-site lysyl residue (K229) that forms the internal aldimine with pyridoxal phosphate. For Escherichia coli serine hydroxymethyltransferase each of these threonine residues has been changed to an alanine residue. The resulting five mutant enzymes were purified and characterized with respect to kinetic and spectral properties. The mutant enzymes T224A and T227A showed no significant changes in kinetic and spectral properties compared to the wild-type enzyme. The T225A and T230A enzymes exhibited differences in K(m) and k(cat) values but exhibited the same spectral properties as the wild-type enzyme. The four threonine residues at positions 224, 225, 227, and 230 do not play a critical role in the mechanism of the enzyme. The T226A enzyme had nearly normal affinity for substrates and coenzymes but had only 3% of the catalytic activity of the wild-type enzyme. The spectrum of the T226A enzyme in the presence of amino acid substrates showed a large absorption maximum at 343 nm with only a small absorption band at 425 nm, unlike the wild-type enzyme whose enzyme-substrate complexes absorb at 425 nm. Rapid reaction studies showed that when amino acid substrates and substrate analogues were added to the T226A enzyme, the internal aldimine absorbing at 422 nm was rapidly converted to a complex absorbing at 343 nm in a second-order process. This was followed by a very slow first-order formation of a complex absorbing at 425 nm. Variation of the initial rapid second-order process as a function of pH suggested that the anionic form of the amino acid forms the first complex with the enzyme. The results are interpreted as being due to the rapid formation of a gem-diamine complex between amino acids and T226A enzyme with a rate-determining formation of the external aldimine. This suggests that Thr-226 plays an important role in converting the gem-diamine complex to the external aldimine complex. Variation of the kinetic constants with amino acid structure suggests that the T226A enzyme distinguishes between substrates and substrate analogues in the formation of the gem-diamine complex
Academic expectations profiles of spanish and portuguese higher education students
Las expectativas académicas de los
estudiantes son hoy reconocidas como una
variable importante en la explicación de su
adaptación y éxito académico. Esa importancia
es mayor en los alumnos del primer año, ya
que, frecuentemente presentan expectativas
iniciales muy elevadas que no siempre llegan
a concretarse. Con la pretensión de conocer
cuáles son esas expectativas iniciales, el trabajo que se presenta analiza el perfil de las mismas en estudiantes de Enseñanza Superior (ES) de primer año. La muestra está
compuesta por 719 estudiantes de diversas
titulaciones académicas de las Universidades
de Vigo-Campus de Ourense y Minho. A los
participantes se les aplicó el Cuestionario
de Percepciones Académicas (CPA). Los
resultados han sido analizados tomando
la nacionalidad y el ámbito de estudio (cientifico, juridico-social, tecnológico). Los resultados muestran que los estudiantes
portugueses tienden a presentar expectativas
más elevadas en general, traduciéndose en
una valoración superior de su entrada en la Universidad. A su vez, considerando las siete
dimensiones de expectativas evaluadas, se comprueba un perfil similar para ambos países en relación a las expectativas más o menos
valoradas. Se destacan las expectativas de
obtener una formación que permita acceder
a un buen empleo o carrera, en primer lugar,
y las expectativas de tener en la Universidad
oportunidades de desarrollo personal y social,
en segundo lugar, como las más valoradas por
los estudiantes.Academic expectations are recognized as
an important variable for students’ adjustment
and academic success. This importance is higher for first year students, because they often present initial expectations that may
not be met. Aiming at identifying these initial
expectations, this study presents and analyses the profile of first year students' academic expectations. The sample included 719
students attending different undergraduate
programs at University of Vigo - Campus
of Ourense, and at University of Minho.
Participants completed the Academic
Perceptions Questionnaire (APQ). Analyses
were based on students’ nationality and study domain (scientific, juridical-social, technological). Results show that Portuguese
students present higher expectations, in
general, which shows they attribute a higher
value to their access to University. On the other
hand, and regarding the seven dimensions of
assessed expectations, we can see that this
difference in average scores is not structural,
because there is a similar pattern of higher and
lower expectations, for both countries. The most valued expectations are, in first place, expectations of having an education that will
lead to a good job or career, and in second
place, expectations of having opportunities of
personal and social development in University
Osteochondral impaction of the posterior acetabular surface without cortical fracture of any wall or column: an undescribed pattern of acetabular injury
Surgical treatment of a unusual acetabular fracture is described. This fracture was characterized by impaction and breaking down of the posterior articular surface and comminution of lamina quadrilatera lower portion, without cortical fracture of both columns. The fracture was treated surgically through the Kocher–Langenbeck approach. A small hole was created in the acetabulum posterior wall, the impacted fragment was reduced, and the bone defect was filled with autologous bone from the greater trochanter. A plate was shaped in order to fix both bone graft and fractured fragment
Clinical features of patients with type 2 diabetes with and without Covid-19: a case control study (CoViDiab I)
Aims: To evaluate whether subjects with diabetes hospitalized for Coronavirus disease-19 (Covid-19) represent a subgroup of patients with high-risk clinical features compared to patients with diabetes without Covid-19. Methods: In this case-control study 79 patients with type 2 diabetes out of 354 adults hospitalized for Covid-19 and 158 controls with type 2 diabetes but without Covid-19, matched for age and gender, were enrolled. Medical history and concomitant therapies were retrieved from medical charts and compared between cases and controls, controlling for confounders. Results: Fully-adjusted multivariate logistic regression model showed that previous CVD history did not differ between patients with and without Covid-19 (odds ratio 1.40, 95% confidence interval [CI]: 0.59–3.32, p = 0.45). A higher prevalence of chronic obstructive pulmonary disease (COPD) (OR 3.72, 95%CI: 1.42–9.72, p = 0.007) and of chronic kidney disease (CKD) (OR 3.08, 95%CI: 1.18–8.06, p = 0.022) and a lower prevalence of ever smokers (OR 0.30, 95%CI: 0.13–0.67, p = 0.003), of users of lipid lowering agents (OR 0.26, 95%CI: 0.12–0.54, p < 0.001), and of anti-hypertensive drugs (OR 0.39, 95%CI: 0.16–0.93, p = 0.033) were found among cases. Conclusions: CVD prevalence does not differ between people with diabetes with and without Covid-19 requiring hospitalization. An increased prevalence of COPD and of CKD in Covid-19 patients with type 2 diabetes is suggested. These findings aid to clarify the relationship between underlying conditions and SARS-CoV-2 infection in the high-risk group of patients with diabetes
Inverse Modeling for MEG/EEG data
We provide an overview of the state-of-the-art for mathematical methods that
are used to reconstruct brain activity from neurophysiological data. After a
brief introduction on the mathematics of the forward problem, we discuss
standard and recently proposed regularization methods, as well as Monte Carlo
techniques for Bayesian inference. We classify the inverse methods based on the
underlying source model, and discuss advantages and disadvantages. Finally we
describe an application to the pre-surgical evaluation of epileptic patients.Comment: 15 pages, 1 figur
Enhancing the early student experience
This paper is concerned with identifying how the early student experience can be enhanced in order to improve levels of student retention and achievement. The early student experience is the focus of this project as the literature has consistently declared the first year to be the most critical in shaping persistence decisions. Programme managers of courses with high and low retention rates have been interviewed to identify activities that appear to be associated with good retention rates. The results show that there are similarities in the way programmes with high retention are run, with these features not being prevalent on programmes with low retention. Recommendations of activities that appear likely to enhance the early student experience are provided
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