53,492 research outputs found

    Academic libraries and learning support in the electronic environment

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    Learning and teaching techniques are changing in the new electronic environment. Students are asked to gather information from different sources, most of them in electronic formats. Libraries have to adapt their buildings and services to meet their users needs continuously. Amongst the means librarians have included to support learning are electronic based information and learning resources, a better provision of IT technologies, working environments for different types of learning, digital reference services, information literacy skills and the possibility of accessing all these facilities, resources and services at any time. The conclusion indicates that librarians should continuously improve electronic information and learning resources, as well as discovering new ways to approach students

    Identification of arches in 2D granular packings

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    We identify arches in a bed of granular disks generated by a molecular dynamic-type simulation. We use the history of the deposition of the particles to identify the supporting contacts of each particle. Then, arches are defined as sets of mutually stable disks. Different packings generated through tapping are analyzed. The possibility of identifying arches from the static structure of a deposited bed, without any information on the history of the deposition, is discussed.Comment: 12 pages, 7 figure

    Distribution-free tests of fractional cointegration

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    We propose tests of the null of spurious relationship against the alternative of fractional cointegration among the components of a vector of fractionally integrated time series. Our test statistics have an asymptotic chi-square distribution under the null and rely on generalized least squares–type of corrections that control for the short-run correlation of the weak dependent components of the fractionally integrated processes. We emphasize corrections based on nonparametric modelization of the innovations’ autocorrelation, relaxing important conditions that are standard in the literature and, in particular, being able to consider simultaneously (asymptotically) stationary or nonstationary processes. Relatively weak conditions on the corresponding short-run and memory parameter estimates are assumed. The new tests are consistent with a divergence rate that, in most of the cases, as we show in a simple situation, depends on the cointegration degree. Finite-sample properties of the tests are analyzed by means of a Monte Carlo experiment.Publicad

    Pattern formation without heating in an evaporative convection experiment

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    We present an evaporation experiment in a single fluid layer. When latent heat associated to the evaporation is large enough, the heat flow through the free surface of the layer generates temperature gradients that can destabilize the conductive motionless state giving rise to convective cellular structures without any external heating. The sequence of convective patterns obtained here without heating, is similar to that obtained in B\'enard-Marangoni convection. This work present the sequence of spatial bifurcations as a function of the layer depth. The transition between square to hexagonal pattern, known from non-evaporative experiments, is obtained here with a similar change in wavelength.Comment: Submitted to Europhysics Letter

    The level of provision of specialist palliative care services in Scotland: an international benchmarking study

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    Objectives: Comparative benchmarking of specialist palliative care (SPC) services across jurisdictions can be used to assess the adequacy of provision. Published in 2016, the Scottish Atlas of Palliative Care unlocks the possibility of benchmarking Scotland’s provision against other European Union (EU) countries. Our objectives were to describe the provision of SPC services in Scotland and compare this with other EU countries, assessing coverage against European norms. Methods: We conducted a secondary analysis of data collected as part for the Scottish Atlas by structured telephone (n=33) or online (n=3) survey with informants from 14 territorial health boards and 15 hospices who provided information about SPC services in their locality. National-level Scottish data were compared with data from other EU countries allowing ranking for each service type and service coverage as calculated against European Association for Palliative Care norms. Results: Scotland had a total of 23 SPC inpatient units containing 349 beds, 27 SPC hospital support teams and 38 SPC home care teams. Relative to other EU countries, Scotland ranked seventh for provision of SPC inpatient units and hospital support teams, and fifth for home care teams. Coverage for these services was 85%, 100% and 72%, respectively. Conclusion: Scotland is positioned among the top 10 EU countries for the level of provision of SPC services. National policy in Scotland has focused on the delivery of palliative care at home or in a homely setting. These data support a focus on developing services in community settings to meet Scotland’s policy ambitions

    Integrating curriculum-based dynamic assessment in computerized adaptive testing: Development and predictive validity of the EDPL-BAI battery on reading competence

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    In recent decades, there have been significant changes in the conceptualization of reading as well as in the perception of how this activity should be assessed. Interest in the analysis of reading processes has led to the emergence of new explanatory models based primarily on the contributions of cognitive psychology. In parallel, there have been notable advances in measurement procedures, especially in models based on Item Response Theory (IRT), as well as in the capacity and performance of specific software programs that allow data to be managed and analyzed. These changes have contributed significantly to the rise of testing procedures such as computerized adaptive tests (CATs), whose fundamental characteristic is that the sequence of items presented in the tests is adapted to the level of competence that the subject manifests. Likewise, the incorporation of elements of dynamic assessment (DA) as the prompts are gradually offered allows for obtaining information about the type and degree of support required to optimize the subject’s performance. In this sense, the confluence of contributions from DA and CATs offers a new possibility for approaching the assessment of learning processes. In this article, we present a longitudinal research developed in two phases, through which a computerized dynamic adaptive assessment battery of reading processes (EDPL-BAI) was configured. The research frame involved 1,831 students (46% girls) from 13 public schools in three regions of Chile. The purpose of this study was to analyze the differential contribution on reading competence of dynamic scores obtained in a subsample composed of 324 (47% girls) students from third to sixth grade after the implementation of a set of adaptive dynamic tests of morpho-syntactic processes. The results achieved in the structural equation modeling indicate a good global fit. Individual relationships show a significant contribution of calibrated score that reflects estimated knowledge level on reading competence, as well as dynamic scores based on the assigned value of graduated prompts required by the students. These results showed significant predictive values on reading competence and incremental validity in relation to predictions made by static criterion tests

    Science as a Form of Life and Cross-disciplinarity: Mariano Artigas and Charles S. Peirce

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    According to Charles S. Peirce and to Mariano Artigas, science is the collective and cooperative activity of all those whose lives are animated by the desire to discover the truth. The particular sciences are branches of a common tree. The unity of science is not achieved by the reduction of the special sciences to more basic ones: the new name for the unity of the sciences is cross-disciplinarity. This is not a union of the sciences themselves, but rather the unity and dialogue of scientists, the real inquirers into the truth. In the light of Peirce’s and Artigas’s teachings, we can see that philosophers are in just the right place to call for this unity of sciences. This call should not be seen as promoting a return to the old scientism, but seeks a deep dialogue between the particular sciences and philosophy in order to deal with the presuppositions of the scientific enterprise. The key to the cross-disciplinarity of knowledge is not revolution, but rather shared efforts in a unique mixture of continuity and fallibilism, of affection and reason, of the attempt to understand others’ disciplines as well as our own

    Role of vibrations in the jamming and unjamming of grains discharging from a silo

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    We present experimental results of the jamming of non-cohesive particles discharged from a flat bottomed silo subjected to vertical vibration. When the exit orifice is only a few grain diameter wide, the flow can be arrested due to the formation of blocking arches. Hence, an external excitation is needed to resume the flow. The use of a continuous gentle vibration is a usual technique to ease the flow in such situations. Even though jamming is less frequent, it is still an issue in vibrated silos. There are, in principle, two possible mechanisms through which vibrations may facilitate the flow: (i) a decrease in the probability of the formation of blocking arches, and (ii) the breakage of blocking arches once they have been formed. By measuring the time intervals inside an avalanche during which no particles flow through the outlet, we are able to estimate the probability of breaking a blocking arch by vibrations. The result agrees with the prediction of a bivariate probabilistic model in which the formation of blocking arches is equally probable in vibrated and non-vibrated silos. This indicates that the second aforementioned mechanism is the main responsible for improving the flowability in gently vibrated silos

    Intermittent origin of the large violations of the fluctuation dissipation relations in an aging polymer glass

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    The fluctuation-dissipation relation (FDR) is measured on the dielectric properties of a polymer glass (polycarbonate)in the range 20mHz100Hz20mHz - 100Hz. It is found that after a quench below the glass transition temperature the fluctuation dissipation theorem is strongly violated. The amplitude and the persistence time of this violation are decreasing functions of frequency. At frequencies larger than 1Hz it persists for about 3h3h. The origin of this violation is a highly intermittent dynamics characterized by large fluctuations. The relevance of these results for recent models of aging dynamics are discussed.Comment: to be published in Europhysics Letter

    Hospital volume and outcomes for acute pulmonary embolism: Multinational population based cohort study

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    [Objectives] To evaluate the association between experience in the management of acute pulmonary embolism, reflected by hospital case volume, and mortality.[Design] Multinational population based cohort study using data from the Registro Informatizado de la Enfermedad TromboEmbólica (RIETE) registry between 1 January 2001 and 31 August 2018.[Setting] 353 hospitals in 16 countries.[Participants] 39 257 consecutive patients with confirmed diagnosis of acute symptomatic pulmonary embolism.[Main] outcome measure Pulmonary embolism related mortality within 30 days after diagnosis of the condition.[Results] Patients with acute symptomatic pulmonary embolism admitted to high volume hospitals (>40 pulmonary embolisms per year) had a higher burden of comorbidities. A significant inverse association was seen between annual hospital volume and pulmonary embolism related mortality. Admission to hospitals in the highest quarter (that is, >40 pulmonary embolisms per year) was associated with a 44% reduction in the adjusted odds of pulmonary embolism related mortality at 30 days compared with admission to hospitals in the lowest quarter (<15 pulmonary embolisms per year; adjusted risk 1.3% v 2.3%; adjusted odds ratio 0.56 (95% confidence interval 0.33 to 0.95); P=0.03). Results were consistent in all sensitivity analyses. All cause mortality at 30 days was not significantly reduced between the two quarters (adjusted odds ratio 0.78 (0.50 to 1.22); P=0.28). Survivors showed little change in the odds of recurrent venous thromboembolism (odds ratio 0.76 (0.49 to 1.19)) or major bleeding (1.07 (0.77 to 1.47)) between the low and high volume hospitals.[Conclusions] In patients with acute symptomatic pulmonary embolism, admission to high volume hospitals was associated with significant reductions in adjusted pulmonary embolism related mortality at 30 days. These findings could have implications for management strategies.Peer reviewe
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