Fracture and failure of thermally damaged concrete under tensile loading

Concrete is a brittle composite material where the failure mechanism is closely related to the initiation and propagation of cracks. The presence of microcracks and other defects in concrete allows, unlike in the case of an ideal brittle material, the existence of a failure process that includes the branching and bifurcation of the cracks, which gives rise to the appearance of an inelastic behavior and then to a higher energy consumption during failure and an extension of the zone in which fracture takes place. This work studies the failure behavior of damaged concretes in tension and compares the behavior of concrete of different strength levels and component materials when adopting temperature as the damaging tool. Two water/cement ratios, two types of coarse aggregates and the incorporation of natural pozzolans are included as variables. As a way to evaluate the damage produced in the internal structure of concrete, the dynamic modulus of elasticity was measured on each specimen. Measures of strength, deformability, and fracture energy determined over notched prisms are reported. In a complementary way, the results of compression tests (strength, static modulus of elasticity, and Poisson ratio) over cylindrical specimens are included.Facultad de IngenieríaLaboratorio de Entrenamiento Multidisciplinario para la Investigación Tecnológic

Functional-bandwidth kernel for Support Vector Machine with Functional Data:An alternating optimization algorithm

Functional Data Analysis (FDA) is devoted to the study of data which are functions. Support Vector Ma- chine (SVM) is a benchmark tool for classification, in particular, of functional data. SVM is frequently used with a kernel (e.g.: Gaussian) which involves a scalar bandwidth parameter. In this paper, we pro- pose to use kernels with functional bandwidths. In this way, accuracy may be improved, and the time intervals critical for classification are identified. Tuning the functional parameters of the new kernel is a challenging task expressed as a continuous optimization problem, solved by means of a heuristic. Our experiments with benchmark data sets show the advantages of using functional parameters and the ef- fectiveness of our approach

On the selection of the globally optimal prototype subset for nearest-neighbor classification

The nearest-neighbor classifier has been shown to be a powerful tool for multiclass classification. We explore both theoretical properties and empirical behavior of a variant method, in which the nearest-neighbor rule is applied to a reduced set of prototypes. This set is selected a priori by fixing its cardinality and minimizing the empirical misclassification cost. In this way we alleviate the two serious drawbacks of the nearest-neighbor method: high storage requirements and time-consuming queries. Finding this reduced set is shown to be NP-hard. We provide mixed integer programming (MIP) formulations, which are theoretically compared and solved by a standard MIP solver for small problem instances. We show that the classifiers derived from these formulations are comparable to benchmark procedures. We solve large problem instances by a metaheuristic that yields good classification rules in reasonable time. Additional experiments indicate that prototype-based nearest-neighbor classifiers remain quite stable in the presence of missing values

Fracture and failure of thermally damaged concrete under tensile loading

Concrete is a brittle composite material where the failure mechanism is closely related to the initiation and propagation of cracks. The presence of microcracks and other defects in concrete allows, unlike in the case of an ideal brittle material, the existence of a failure process that includes the branching and bifurcation of the cracks, which gives rise to the appearance of an inelastic behavior and then to a higher energy consumption during failure and an extension of the zone in which fracture takes place. This work studies the failure behavior of damaged concretes in tension and compares the behavior of concrete of different strength levels and component materials when adopting temperature as the damaging tool. Two water/cement ratios, two types of coarse aggregates and the incorporation of natural pozzolans are included as variables. As a way to evaluate the damage produced in the internal structure of concrete, the dynamic modulus of elasticity was measured on each specimen. Measures of strength, deformability, and fracture energy determined over notched prisms are reported. In a complementary way, the results of compression tests (strength, static modulus of elasticity, and Poisson ratio) over cylindrical specimens are included.Facultad de IngenieríaLaboratorio de Entrenamiento Multidisciplinario para la Investigación Tecnológic

Morphology of radio relics I: What causes the substructure of synchrotron emission?

High-resolution radio observations of cluster radio relics often show complex spatial and spectral features. However, it is not clear what these features reveal about the underlying magnetic field properties. We performed three-dimensional magneto-hydrodynamical simulations of merger shock waves propagating through a magnetised, turbulent intracluster medium. Our model includes the diffusive shock acceleration of cosmic-ray electrons, their spatial advection and energy losses at run-time. With this set-up we can investigate the relation between radio substructure and pre-shock plasma conditions in the host cluster. We find that upstream turbulence plays a major role in shaping the properties of radio relics produced downstream. Within the assumption of diffusive shock acceleration, we can reproduce the observed discrepancy between the X-ray derived Mach number of shocks, and the Mach number inferred from radio spectra. Our simulated spectral index maps and profiles across the radio relic also suggest that the standard deviation of the upstream magnetic field must be relatively small ($\sigma_B\leq 1 \, \mu$G) in order to reproduce observations and therefore, radio relics can potentially constrain the distribution of magnetic fields in galaxy clusters outskirts.Comment: Accepted for publication in MNRAS, 22 pages, 25 figure

Predicting the onset and persistence of episodes of depression in primary health care. The predictD-Spain study: Methodology

Background: The effects of putative risk factors on the onset and/or persistence of depression remain unclear. We aim to develop comprehensive models to predict the onset and persistence of episodes of depression in primary care. Here we explain the general methodology of the predictD-Spain study and evaluate the reliability of the questionnaires used. Methods: This is a prospective cohort study. A systematic random sample of general practice attendees aged 18 to 75 has been recruited in seven Spanish provinces. Depression is being measured with the CIDI at baseline, and at 6, 12, 24 and 36 months. A set of individual, environmental, genetic, professional and organizational risk factors are to be assessed at each follow-up point. In a separate reliability study, a proportional random sample of 401 participants completed the test-retest (251 researcher-administered and 150 self-administered) between October 2005 and February 2006. We have also checked 118,398 items for data entry from a random sample of 480 patients stratified by province. Results: All items and questionnaires had good test-retest reliability for both methods of administration, except for the use of recreational drugs over the previous six months. Cronbach's alphas were good and their factorial analyses coherent for the three scales evaluated (social support from family and friends, dissatisfaction with paid work, and dissatisfaction with unpaid work). There were 191 (0.16%) data entry errors. Conclusion: The items and questionnaires were reliable and data quality control was excellent. When we eventually obtain our risk index for the onset and persistence of depression, we will be able to determine the individual risk of each patient evaluated in primary health car

Somatostatin subtype-2 receptor-targeted metal-based anticancer complexes

Conjugates of a dicarba analogue of octreotide, a potent somatostatin agonist whose receptors are overexpressed on tumor cells, with [PtCl 2(dap)] (dap = 1-(carboxylic acid)-1,2-diaminoethane) (3), [(η 6-bip)Os(4-CO 2-pico)Cl] (bip = biphenyl, pico = picolinate) (4), [(η 6-p-cym)RuCl(dap)] + (p-cym = p-cymene) (5), and [(η 6-p-cym)RuCl(imidazole-CO 2H)(PPh 3)] + (6), were synthesized by using a solid-phase approach. Conjugates 3-5 readily underwent hydrolysis and DNA binding, whereas conjugate 6 was inert to ligand substitution. NMR spectroscopy and molecular dynamics calculations showed that conjugate formation does not perturb the overall peptide structure. Only 6 exhibited antiproliferative activity in human tumor cells (IC 50 = 63 ± 2 μ in MCF-7 cells and IC 50 = 26 ± 3 μ in DU-145 cells) with active participation of somatostatin receptors in cellular uptake. Similar cytotoxic activity was found in a normal cell line (IC 50 = 45 ± 2.6 μ in CHO cells), which can be attributed to a similar level of expression of somatostatin subtype-2 receptor. These studies provide new insights into the effect of receptor-binding peptide conjugation on the activity of metal-based anticancer drugs, and demonstrate the potential of such hybrid compounds to target tumor cells specifically. © 2012 American Chemical Society

Can robotic-based top-down rehabilitation therapies improve motor control in children with cerebral palsy? A perspective on the CPWalker project

[EN] Cerebral Palsy (CP) is one of the most severe disabilities in childhood, and it demands important costs in health, education, and social services. CP is caused by damage to or abnormalities inside the developing brain that disrupt the brain's ability to control movement and maintain posture. Furthermore, CP is often associated with sensory deficits, cognition impairments, communication and motor disabilities, behavior issues, seizure disorder, pain, and secondary musculoskeletal problems. According to the literature, motor modules are peripheral measurements related to automatic motor control. There is a lack of evidence of change in motor modules in children with CP when different treatment approaches have been evaluated. Thus, new strategies are needed to improve motor control in this population. Robotic-based therapies are emerging as an effective intervention for gait rehabilitation in motor disorders such as stroke, spinal cord injury, and CP. There is vast clinical evidence that neural plasticity is the central core of motor recovery and development, and on-going studies suggest that robot-mediated intensive therapy could be beneficial for improved functional recovery. However, current robotic strategies are focused on the peripheral neural system (PNS) facilitating the performance of repetitive movements (a bottom-up approach). Since CP affects primarily brain structures, both the PNS and the central nervous system (CNS) should to be integrated in a physical and cognitive rehabilitation therapy (a top-down approach). This paper discusses perspectives of the top-down approach based on a novel robot-assisted rehabilitative system. Accordingly, the CPWalker robotic platform was developed to support novel therapies for CP rehabilitation. This robotic platform (Smart Walker + exoskeleton) is controlled by a multimodal interface enabling the interaction of CP infants with robot-based therapies. The aim of these therapies is to improve the physical skills of infants with CP using a top-down approach, in which motor related brain activity is used to drive robotic physical rehabilitation therapies. Our hypothesis is that the CPWalker concept will promote motor learning and this improvement will lead to significant improvements in automatic motor control.Lerma Lara, S.; Martínez Caballero, I.; Bayón, C.; Del Castillo, M.; Serrano, I.; Raya, R.; Belda Lois, JM.... (2016). Can robotic-based top-down rehabilitation therapies improve motor control in children with cerebral palsy? A perspective on the CPWalker project. Biomedical Research and Clinical Practice. 22-26. doi:10.15761/BRCP.1000106S222

Ribose 2′-O-methylation provides a molecular signature for the distinction of self and non-self mRNA dependent on the RNA sensor Mda5

The 5'-cap-structures of higher eukaryote mRNAs are ribose 2'-O-methylated. Likewise, a number of viruses replicating in the cytoplasm of eukayotes have evolved 2'-O-methyltransferases to modify autonomously their mRNAs. However, a defined biological role of mRNA 2'-O-methylation remains elusive. Here we show that viral mRNA 2'-O-methylation is critically involved in subversion of type-I-interferon (IFN-I) induction. We demonstrate that human and murine coronavirus 2'-O-methyltransferase mutants induce increased IFN-I expression, and are highly IFN-I sensitive. Importantly, IFN-I induction by 2'-O-methyltransferase-deficient viruses is dependent on the cytoplasmic RNA sensor melanoma differentiation-associated gene 5 (MDA5). This link between MDA5-mediated sensing of viral RNA and mRNA 2'-O-methylation suggests that RNA modifications, such as 2'-O-methylation, provide a molecular signature for the discrimination of self and non-self mRNA

One year of AU Mic with HARPS: I - measuring the masses of the two transiting planets

The system of two transiting Neptune-sized planets around the bright, young M-dwarf AU Mic provides a unique opportunity to test models of planet formation, early evolution, and star-planet interaction. However, the intense magnetic activity of the host star makes measuring the masses of the planets via the radial velocity (RV) method very challenging. We report on a 1-year, intensive monitoring campaign of the system using 91 observations with the HARPS spectrograph, allowing for detailed modelling of the ∼600 m s−1 peak-to-peak activity-induced RV variations. We used a multidimensional Gaussian Process framework to model these and the planetary signals simultaneously. We detect the latter with semi-amplitudes of Kb = 5.8 ± 2.5 m s−1 and Kc = 8.5 ± 2.5 m s−1, respectively. The resulting mass estimates, Mb = 11.7 ± 5.0 M⊕ and Mc = 22.2 ± 6.7 M⊕, suggest that planet b might be less dense, and planet c considerably denser than previously thought. These results are in tension with the current standard models of core-accretion. They suggest that both planets accreted a H/He envelope that is smaller than expected, and the trend between the two planets’ envelope fractions is the opposite of what is predicted by theory