539 research outputs found
Modelling and simulation of the effect loading on structures using and adaptive blending of discrete and finite element methods
We present a new computational model for predicting the effect of blast loading on structures. The model is based in the adaptive coupling of the finite element method (FEM) and the discrete element method (DEM) for the accurate reproduction of multifracturing and failure of structures under blast loading. In the paper we briefly describe the basis of the coupled DEM/FEM technology and demonstrate its efficiency in its application to the study of the effect of blast loading on a masonry wall, a masonry tunnel and a double curvature dam
Advances in the development of the discrete element method for excavation processes
This work presents new developments of the discrete element method improving e ciency and accuracy of modelling of rock-like materials, especially in excavation processes.Postprint (published version
Validación del Cuestionario de Autoevaluación de la Creatividad en la Enseñanza Universitaria CACEU-2010
La creatividad es un vector formativo de la
enseñanza y de las relaciones entre estudiantes y profesores
en la Educación Superior. A tal fin, el Cuestionario
de Autoevaluación de la Creatividad en la Enseñanza
Universitaria (CACEU-2010) se ha diseñado para
conocer cómo comprenden los profesores universitarios
la creatividad aplicada a su enseñanza y facilitar su autoevaluación.
Se estructuró como una escala de autoinforme,
conformada por 44 Ãtemes. Se estudió la validez
de contenido, realizada por jueces expertos. La
fiabilidad se obtuvo con el método Alpha de Cronbach,
y el parámetro obtuvo valores entre 0,70 y 0,94 para
las diferentes subescalas utilizadas
Gastrostomy uptake in motor neurone disease: a mixed-methods study of patients’ decision making
Objectives: Gastrostomy decision making is a complicated, multifaceted process for people with motor neuron disease (MND). This study explored demographic and disease-related factors that may impact on gastrostomy uptake; and reasons why people with MND accepted or declined gastrostomy, with a focus on how perceptions of swallowing and nutrition may influence decision making.Design: Prospective, cross sectional, mixed methods.Setting: An Australian multidisciplinary, specialty MND Service.Participants: 33 patients were recommended gastrostomy by the treating medical specialist. 16 of 33 were invited to participate in the prospective decision making study; of whom 10 provided informed consent.Primary and secondary outcome measures: Demographic and disease-related factors contributing to uptake are described. A stepped approach was applied to gain a comprehensive understanding of why people with MND accept or decline gastrostomy. Instruments included standardised assessments, nutrition survey and semistructured interview. Data were collected at three separate appointments, spanning a 3-week period.Results: Gastrostomy uptake was 73% following medical specialist recommendation. Participants took days, weeks or months to consider their preferences, with lengthy hospital waiting times for the procedure. Gender, site of onset and rate of disease progression were observed to contribute to uptake. Age and symptom duration did not. Integration of quantitative and qualitative data suggests that patient perceptions of swallowing and nutrition contribute to gastrostomy acceptance; however, the decision making process is heterogeneous and these factors may not be the sole or primary reasons for acceptance. Other reported factors included: reducing carer burden, improving quality of life, increasing independence, continuing participation in social outings and gaining control.Conclusions: Future research may give greater insight into how healthcare organisations can better facilitate gastrostomy decision making, to meet the needs of people living with MND. Larger, prospective, multisite studies may build on these findings to better inform clinical guidelines and minimise the impacts of delayed gastrostomy insertion
Charge transport through a single molecule of trans-1-bis-diazofluorene [60]fullerene
Fullerenes have attracted interest for their possible applications in various
electronic, biological, and optoelectronic devices. However, for efficient use
in such devices, a suitable anchoring group has to be employed that forms
well-defined and stable contacts with the electrodes. In this work, we propose
a novel fullerene tetramalonate derivate functionalized with trans-1
4,5-diazafluorene anchoring groups. The conductance of single-molecule
junctions, investigated in two different setups with the mechanically
controlled break junction technique, reveals the formation of molecular
junctions at three conductance levels. We attribute the conductance peaks to
three binding modes of the anchoring groups to the gold electrodes. Density
functional theory calculations confirm the existence of multiple binding
configurations and calculated transmission functions are consistent with
experimentally determined conductance values.Comment: 22 pages, 6 figure
Extended QCD(2) from dimensional projection of QCD(4)
We study an extended QCD model in (1+1) dimensions obtained from QCD in 4D by
compactifying two spatial dimensions and projecting onto the zero-mode
subspace. We work out this model in the large limit and using light cone
gauge but keeping the equal-time quantization. This system is found to induce a
dynamical mass for transverse gluons -- adjoint scalars in QCD(2), and to
undergo a chiral symmetry breaking with the full quark propagators yielding
non-tachyonic, dynamical quark masses, even in the chiral limit. We study
quark-antiquark bound states which can be classified in this model by their
properties under Lorentz transformations inherited from 4D. The scalar and
pseudoscalar sectors of the theory are examined and in the chiral limit a
massless ground state for pseudoscalars is revealed with a wave function
generalizing the so called 't Hooft pion solution.Comment: JHEP class, 16 pages, 3 figures. Change in the title, some
improvements in section 2, minors changes and comments added in introduction
and conclusions. References added. Version appearing in JHE
Pre-pregnancy maternal obesity associates with endoplasmic reticulum stress in human umbilical vein endothelium
Obesity associates with the endoplasmic reticulum (ER) stress-induced endothelial dysfunction. Pregnant women with pre-pregnancy maternal obesity (PGMO) may transfer this potential risk to their offspring; however, whether ER stress occurs and associates with foetoplacental endothelial dysfunction in PGMO is unknown. We studied the l-arginine transport and nitric oxide (NO) synthesis in human umbilical vein endothelial cells (HUVECs) from women with PGMO or with a normal pre-pregnancy weight. We analysed the expression and activation of the ER stress sensors protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring enzyme 1α (IRE1α), and activating transcription factor 6 (ATF6). PGMO associated with lower endothelial NO synthase activity due to increased Thr-inhibitor and decreased Ser-stimulator phosphorylation. However, higher expression and activity of the human cationic amino acid transporter 1 was found. PGMO caused activation of PERK and its downstream targets eukaryotic initiation factor 2 (eIF2α), C/EBP homologous protein 10 (CHOP), and tribbles-like protein 3 (TRB3). Increased IRE1α protein abundance (but not its phosphorylation or X-box binding protein 1-mRNA splicing) and increased c-Jun N-terminal kinase 1 phosphorylation was seen in PGMO. A preferential nuclear location of the activating transcription factor 6 (ATF6) was found in HUVECs from PGMO. All the changes seen in PGMO were blocked by TUDCA but unaltered by tunicamycin. Thus, PGMO may determine a state of ER stress via upregulation of the PERK-eIF2α-CHOP-TRB3 axis signalling in HUVECs. This phenomenon results in foetoplacental vascular endothelial dysfunction at birth
Enamel Caries Detection and Diagnosis:An Analysis of Systematic Reviews
Detection and diagnosis of caries-typically undertaken through a visual-tactile examination, often with supporting radiographic investigations-is commonly regarded as being broadly effective at detecting caries that has progressed into dentine and reached a threshold where restoration is necessary. With earlier detection comes an opportunity to stabilize disease or even remineralize the tooth surface, maximizing retention of tooth tissue and preventing a lifelong cycle of restoration. We undertook a formal comparative analysis of the diagnostic accuracy of different technologies to detect and inform the diagnosis of early caries using published Cochrane systematic reviews. Forming the basis of our comparative analysis were 5 Cochrane diagnostic test accuracy systematic reviews evaluating fluorescence, visual or visual-tactile classification systems, imaging, transillumination and optical coherence tomography, and electrical conductance or impedance technologies. Acceptable reference standards included histology, operative exploration, or enhanced visual assessment (with or without tooth separation) as appropriate. We conducted 2 analyses based on study design: a fully within-study, within-person analysis and a network meta-analysis based on direct and indirect comparisons. Nineteen studies provided data for the fully within-person analysis and 64 studies for the network meta-analysis. Of the 5 technologies evaluated, the greatest pairwise differences were observed in summary sensitivity points for imaging and all other technologies, but summary specificity points were broadly similar. For both analyses, the wide 95% prediction intervals indicated the uncertainty of future diagnostic accuracy across all technologies. The certainty of evidence was low, downgraded for study limitations, inconsistency, and indirectness. Summary estimates of diagnostic accuracy for most technologies indicate that the degree of certitude with which a decision is made regarding the presence or absence of disease may be enhanced with the use of such devices. However, given the broad prediction intervals, it is challenging to predict their accuracy in any future "real world" context
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