335 research outputs found

    Analysis of the dyscalculia with the implementation of a design workshop in CATIA in a primary school in Puebla

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    In a rural context primary school where a pilot program of full-time schools was promoted and taking into account the component of the new curricular autonomy model 2017. A design and automation workshop was implemented using CATIA software, with the aim of demonstrating that primary students can overcome deficiencies in mathematical skills such as dyscalculia. The workshop was conducted with ten students between six and twelve years' old who, due to their rural context, have little contact with technology. For the realization of this workshop, a survey was carried out for the parents and for the children where the full acceptance of the workshop was manifested. In the same way, the participation of the Technological University of Puebla (UTP) was carried out through mechatronic engineering, which was in charge of teaching the workshop, through the management according to the new educational model. The CATIA software visibly favored students' mathematical skills when designing a march, in addition to reducing school absenteeism and generating a product (wooden tractor) that has more significant benefits than the famous Japanese toy. The evaluation of the project was registered in rubrics in a span of three phases. The end of the whole process we concluded that, due to its low cost, it is possible to implement this workshop in all federal and state primaries regardless of their context and also that any child can operate the calculation using CATIA. With this last observation, we demonstrate that dyscalculia is a myth

    Advances in the design of (nano)formulations for delivery of antisense oligonucleotides and small interfering RNA: Focus on the central nervous system

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    RNA-based therapeutics have emerged as one of the most powerful therapeutic options used for the modulation of gene/protein expression and gene editing with the potential to treat neurodegenerative diseases. However, the delivery of nucleic acids to the central nervous system (CNS), in particular by the systemic route, remains a major hurdle. This review will focus on the strategies for systemic delivery of therapeutic nucleic acids designed to overcome these barriers. Pathways and mechanisms of transport across the blood-brain barrier which could be exploited for delivery are described, focusing in particular on smaller nucleic acids including antisense oligonucleotides (ASOs) and small interfering RNA (siRNA). Approaches used to enhance delivery including chemical modifications, nanocarrier systems, and target selection (cell-specific delivery) are critically analyzed. Learnings achieved from a comparison of the successes and failures reported for CNS delivery of ASOs versus siRNA will help identify opportunities for a wider range of nucleic acids and accelerate the clinical translation of these innovative therapies

    Impurity Effect on the In-plane Penetration Depth of the Organic Superconductors Îș\kappa-(BEDT-TTF)2X_2X (XX = Cu(NCS)2_2 and Cu[N(CN)2_2]Br)

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    We report the in-plane penetration depth λ∄\lambda_{\parallel} of single crystals Îș\kappa-(BEDT-TTF)2X_2X (X=X= Cu(NCS)2_2 and Cu[N(CN)2_2]Br) by means of the reversible magnetization measurements under the control of cooling-rate. In XX = Cu(NCS)2_2, λ∄(0)\lambda_{\parallel}(0) as an extrapolation toward TT = 0 K does not change by the cooling-rate within the experimental accuracy, while TcT_{\textrm{c}} is slightly reduced. On the other hand, in XX = Cu[N(CN)2_2]Br, λ∄(0)\lambda_{\parallel}(0) indicates a distinct increase by cooling faster. The different behavior of λ∄(0)\lambda_{\parallel}(0) on cooling-rate between the two salts is quantitatively explained in terms of the local-clean approximation (London model), considering that the former salt belongs to the very clean system and the later the moderate clean one. The good agreement with this model demonstrates that disorders of ethylene-group in BEDT-TTF introduced by cooling faster increase the electron(quasiparticle)-scattering, resulting in shorter mean free path.Comment: 8 pages, 9 figure

    Degradation of a benzene–toluene mixture by hydrocarbon-adapted bacterial communities

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    We examined the rate of degradation of a benzene–toluene mixture in aerobic microcosms prepared with samples of an aquifer that lies below a petrochemical plant (SIReN, UK). Five samples exposed to different concentrations of benzene (from 0.6 to 317 mg l−1) were used. Fast degradation (approx. 1–6 mg l−1 day−1) of both contaminants was observed in all groundwater samples and complete degradation was recorded by the seventh day except for one sample. We also identified the microbial community in each of the samples by culture-independent techniques. Two of the less impacted samples harbour the aerobic benzene degrader Pseudomonas fluorescens, while Acidovorax and Arthrobacter spp. were found in the most polluted sample and are consistent with the population observed in situ. Hydrogenophaga was found in the deepest sample while Rhodoferax spp. were recovered in an alkaline sample (pH 8.4) and may also be implicated in benzene degradation. Time series analysis shows that each of the samples has a different community but they remain stable over the degradation period. This study provides new information on a well not previously studied (no. 309s) and confirms that adapted communities have the ability to degrade hydrocarbon mixtures and could be used in further bioaugmentation approaches in contaminated sites

    Evidence for structural and electronic instabilities at intermediate temperatures in Îș\kappa-(BEDT-TTF)2_{2}X for X=Cu[N(CN)2_{2}]Cl, Cu[N(CN)2_{2}]Br and Cu(NCS)2_{2}: Implications for the phase diagram of these quasi-2D organic superconductors

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    We present high-resolution measurements of the coefficient of thermal expansion α(T)=∂ln⁥l(T)/∂T\alpha (T)=\partial \ln l(T)/\partial T of the quasi-twodimensional (quasi-2D) salts Îș\kappa-(BEDT-TTF)2_2X with X = Cu(NCS)2_2, Cu[N(CN)2_2]Br and Cu[N(CN)2_2]Cl. At intermediate temperatures (B), distinct anomalies reminiscent of second-order phase transitions have been found at T∗=38T^\ast = 38 K and 45 K for the superconducting X = Cu(NCS)2_2 and Cu[N(CN)2_2]Br salts, respectively. Most interestingly, we find that the signs of the uniaxial pressure coefficients of T∗T^\ast are strictly anticorrelated with those of TcT_c. We propose that T∗T^\ast marks the transition to a spin-density-wave (SDW) state forming on minor, quasi-1D parts of the Fermi surface. Our results are compatible with two competing order parameters that form on disjunct portions of the Fermi surface. At elevated temperatures (C), all compounds show α(T)\alpha (T) anomalies that can be identified with a kinetic, glass-like transition where, below a characteristic temperature TgT_g, disorder in the orientational degrees of freedom of the terminal ethylene groups becomes frozen in. We argue that the degree of disorder increases on going from the X = Cu(NCS)2_2 to Cu[N(CN)2_2]Br and the Cu[N(CN)2_2]Cl salt. Our results provide a natural explanation for the unusual time- and cooling-rate dependencies of the ground-state properties in the hydrogenated and deuterated Cu[N(CN)2_2]Br salts reported in the literature.Comment: 22 pages, 7 figure

    The Dependence of the Superconducting Transition Temperature of Organic Molecular Crystals on Intrinsically Non-Magnetic Disorder: a Signature of either Unconventional Superconductivity or Novel Local Magnetic Moment Formation

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    We give a theoretical analysis of published experimental studies of the effects of impurities and disorder on the superconducting transition temperature, T_c, of the organic molecular crystals kappa-ET_2X and beta-ET_2X (where ET is bis(ethylenedithio)tetrathiafulvalene and X is an anion eg I_3). The Abrikosov-Gorkov (AG) formula describes the suppression of T_c both by magnetic impurities in singlet superconductors, including s-wave superconductors and by non-magnetic impurities in a non-s-wave superconductor. We show that various sources of disorder lead to the suppression of T_c as described by the AG formula. This is confirmed by the excellent fit to the data, the fact that these materials are in the clean limit and the excellent agreement between the value of the interlayer hopping integral, t_perp, calculated from this fit and the value of t_perp found from angular-dependant magnetoresistance and quantum oscillation experiments. If the disorder is, as seems most likely, non-magnetic then the pairing state cannot be s-wave. We show that the cooling rate dependence of the magnetisation is inconsistent with paramagnetic impurities. Triplet pairing is ruled out by several experiments. If the disorder is non-magnetic then this implies that l>=2, in which case Occam's razor suggests that d-wave pairing is realised. Given the proximity of these materials to an antiferromagnetic Mott transition, it is possible that the disorder leads to the formation of local magnetic moments via some novel mechanism. Thus we conclude that either kappa-ET_2X and beta-ET_2X are d-wave superconductors or else they display a novel mechanism for the formation of localised moments. We suggest systematic experiments to differentiate between these scenarios.Comment: 18 pages, 5 figure

    Circularity in fisheries data weakens real world prediction

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    The systematic substitution of direct observational data with synthesized data derived from models during the stock assessment process has emerged as a low-cost alternative to direct data collection efforts. What is not widely appreciated, however, is how the use of such synthesized data can overestimate predictive skill when forecasting recruitment is part of the assessment process. Using a global database of stock assessments, we show that Standard Fisheries Models (SFMs) can successfully predict synthesized data based on presumed stock-recruitment relationships, however, they are generally less skillful at predicting observational data that are either raw or minimally filtered (denoised without using explicit stock-recruitment models). Additionally, we find that an equation-free approach that does not presume a specific stock-recruitment relationship is better than SFMs at predicting synthesized data, and moreover it can also predict observational recruitment data very well. Thus, while synthesized datasets are cheaper in the short term, they carry costs that can limit their utility in predicting real world recruitment.https://www.nature.com/articles/s41598-020-63773-3Published versio

    Assessment of the load-velocity profile in the free-weight prone bench pull exercise through different velocity variables and regression models

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    This aims of this study were (I) to determine the velocity variable and regression model which best fit the load-velocity relationship during the free-weight prone bench pull exercise, (II) to compare the reliability of the velocity attained at each percentage of the one-repetition maximum (1RM) between different velocity variables and regression models, and (III) to compare the within- and between-subject variability of the velocity attained at each %1RM. Eighteen men (14 rowers and four weightlifters) performed an incremental test during the free-weight prone bench pull exercise in two different sessions. General and individual load-velocity relationships were modelled through three velocity variables (mean velocity [MV], mean propulsive velocity [MPV] and peak velocity [PV]) and two regression models (linear and second-order polynomial). The main findings revealed that (I) the general (Pearson's correlation coefficient [r] range = 0.964-0.973) and individual (median r = 0.986 for MV, 0.989 for MPV, and 0.984 for PV) load-velocity relationships were highly linear, (II) the reliability of the velocity attained at each %1RM did not meaningfully differ between the velocity variables (coefficient of variation [CV] range = 2.55-7.61% for MV, 2.84-7.72% for MPV and 3.50-6.03% for PV) neither between the regression models (CV range = 2.55-7.72% and 2.73-5.25% for the linear and polynomial regressions, respectively), and (III) the within-subject variability of the velocity attained at each %1RM was lower than the between-subject variability for the light-moderate loads. No meaningful differences between the within- and between-subject CVs were observed for the MV of the 1RM trial (6.02% vs. 6.60%; CVratio = 1.10), while the within-subject CV was lower for PV (6.36% vs. 7.56%; CVratio = 1.19). These results suggest that the individual load-MV relationship should be determined with a linear regression model to obtain the most accurate prescription of the relative load during the free-weight prone bench pull exercise
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