Interpreting the Hours-Technology time-varying relationship

We investigate the time varying relation between hours and technology shocks using a structural business cycle model. We propose an RBC model with a Constant Elasticity of Substitution (CES) production function that allows for capital- and labor-augmenting technology shocks. We estimate the model with Bayesian techniques. In the full sample, we find (i) evidence in favor of a less than unitary elasticity of substitution (rejecting Cobb-Douglas) and (ii) a sizable role for capital augmenting shock for business cycles fluctuations. In rolling sub-samples, we document that the transmission of technology shocks to hours worked has been varying over time. We argue that this change is due to the increase of the elasticity of factor substitution. That is, labor and capital became less complementary throughout the sample inducing a change in the sign and size of the response of hours. We conjecture that this change may have been induced by a change in the skill composition of the labor input.Hours Worked and Business Cycles, Bayesian Methods.

A Cross-Country Estimation of the Elasticity of Substitution between Labor and Capital in Manufacturing Industries

This paper presents a simple methodology to estimate the elasticity of substitution between labor and capital for firms operating in perfectly competitive markets with CRS production functions. It is applied in a cross-country sample to 28 3-digit ISIC manufacturing industries. The econometric procedure relies on measures of sectorial capital stock, that are estimated for a sample of more than 30 countries. Unlike older studies, the estimates are consistent with hicks-neutral cross-country technology differences. The results reveal that in most industries the elasticity of substitution is smaller than one, rejecting the null hypothesis of Cobb-Douglas production functions. The paper provides then an estimation of ¾LK at a level of aggregation extremely useful for research in the international trade literature.

The contribution of schooling in development accounting: Results from a nonparametric upper bound

How much would output increase if underdeveloped economies were to increase their levels of schooling? We contribute to the development accounting literature by describing a non-parametric upper bound on the increase in output that can be generated by more schooling. The advantage of our approach is that the upper bound is valid for any number of schooling levels with arbitrary patterns of substitution/complementarity. Another advantage is that the upper bound is robust to certain forms of endogenous technology response to changes in schooling. We also quantify the upper bound for all economies with the necessary data, compare our results with the standard development accounting approach, and provide an update on the results using the standard approach for a large sample of countries.development accounting, imperfect substitution

The Contribution of Schooling in Development Accounting: Results from a Nonparametric Upper Bound

How much would output increase if underdeveloped economies were to increase their levels of schooling? We contribute to the development accounting literature by describing a non-parametric upper bound on the increase in output that can be generated by more schooling. The advantage of our approach is that the upper bound is valid for any number of schooling levels with arbitrary patterns of substitution/complementarity. Another advantage is that the upper bound is robust to certain forms of endogenous technology response to changes in schooling. We also quantify the upper bound for all economies with the necessary data, compare our results with the standard development accounting approach, and provide an update on the results using the standard approach for a large sample of countries.

Assessing people with visual impairments’ access to information, awareness and satisfaction with high-tech assistive technology

Assistive technology (AT) devices are designed to help people with visual impairments (PVIs) perform activities that would otherwise be difficult or impossible. Devices specifically designed to assist PVIs by attempting to restore sight or substitute it for another sense have a very low uptake rate. This study, conducted in England, aimed to investigate why this is the case by assessing accessibility to knowledge, awareness, and satisfaction with AT in general and with sensory restoration and substitution devices in particular. From a sample of 25 PVIs, ranging from 21 to 68 years old, results showed that participants knew where to find AT information; however, health care providers were not the main source of this information. Participants reported good awareness of different ATs, and of technologies they would not use, but reported poor awareness of specific sensory substitution and restoration devices. Only three participants reported using AT, each with different devices and varying levels of satisfaction. The results from this study suggest a possible breakdown in communication between health care providers and PVIs, and dissociation between reported AT awareness and reported access to AT information. Moreover, awareness of sensory restoration and substitution devices is poor, which may explain the limited use of such technology

Neutron diffraction studies on liquids

The above examples serve to illustrate the extent to which neutron diffraction isotopic substitution methods have been used to determine interatomic structure in a wide range of liquid and amorphous systems. The direct determination of pair radial functions not only offers a means of characterising the different structures in liquids, but also provides theorists with information to construct more realistic model potentials which can be used to explore properties in regimes not currently accessible to experiment.\ud \ud It is anticipated that the NDIS methods will continue to be developed and applied to a wider range of systems. The construction and commissioning of new diffractometers with higher count rates, such as D20 and D4C at ILL, and GEM at ISIS with an optimised sample environment for work at non-ambient conditions will enable new and more extensive research to be undertaken. Besides the many problems of immediate interest suggested at the end of some sections, there are several investigations which will become feasible in the longer term as the technology develops. These include: (i) the use of isotopes such as 12C and 13C which will enable detailed and extensive structural studies to be carried out on a wide range of biologically significant materials, and (ii) the exploitation of higher count rates to investigate changes of structure as a chemical reaction occurs

A strong magneto-optical activity in rare-earth La3+ substituted M-type strontium ferrites

The Creative Commons Attribution 3.0 Unported License to their work.M-type strontium ferrites with substitution of Sr2+ by rare-earth La3+ were prepared by conventional ceramic technology. The structure, magnetic properties, and magneto-optical Kerr activity of Sr1−xLaxFe12O19 (x = 0, 0.05, 0.10, 0.15, 0.20) were investigated by x-ray diffraction (XRD), vibrating sample magnetometer (VSM), and magneto-optical ellipsometry, respectively. X-ray diffraction showed that the samples sintered at 1290 °C for 3 h were single M-type hexagonal ferrites. The magnetic properties were remarkably changed due to the valence change of Fe ions induced by the substitution of La ions. Most significantly, an important magneto-optical activity was induced in the La3+ substituted M-type strontium ferrites around 3 eV.The authors acknowledge the financial support from the National Natural Science Foundation of China under Grant Nos. 50672001 and 51072002, the 211 Project of Anhui University and from the Spanish Ministry of Education and Science under project MAT2009-14534-C03-03. L. Fernandez- Garcia acknowledges the JAE program for a PhD grant.Peer reviewe

ONE-TO-ONE iPAD TECHNOLOGY: PERCEPTIONS VERSUS PRACTICE

This study sought to determine how iPads were used for instruction in the secondary schools of a suburban school district as well as determine if a relationship existed between teacher beliefs about technology and the potential level of transformative integration of the devices in classroom instruction. The Technological Pedagogical Content Knowledge (TPACK) and Substitution, Augmentation, Modification, and Redefinition (SAMR) models comprised the theoretical framework for this study to facilitate discussion about the level of instructional transformation that resulted from the use of iPad technology. This study utilized the Technology Uses and Perceptions Survey (TUPS) and Technology Integration Matrix Reflection (TIM-R) tool from the Florida Center for Instructional Technology. Descriptive statistics were used to show the variety of instructional modes for which iPads were being used (as measured by the TUPS). Correlational analyses determined that positive a relationship existed between teacher perceptions about technology (as measured by the TUPS) and the use of iPads in the classroom. However, no significant relationship existed between these perceptions and the potential level of transformative technology integration in the classroom. The findings of this study will contribute to the body of research on the integration of instructional technology (specifically one-to-one computing devices) in the classroom and help inform the technology program and professional development of the sample district

Does the choice of nucleotide substitution models matter topologically?

Background: In the context of a master level programming practical at the computer science department of the Karlsruhe Institute of Technology, we developed and make available an open-source code for testing all 203 possible nucleotide substitution models in the Maximum Likelihood (ML) setting under the common Akaike, corrected Akaike, and Bayesian information criteria. We address the question if model selection matters topologically, that is, if conducting ML inferences under the optimal, instead of a standard General Time Reversible model, yields different tree topologies. We also assess, to which degree models selected and trees inferred under the three standard criteria (AIC, AICc, BIC) differ. Finally, we assess if the definition of the sample size (#sites versus #sites × #taxa) yields different models and, as a consequence, different tree topologies. Results: We find that, all three factors (by order of impact: nucleotide model selection, information criterion used, sample size definition) can yield topologically substantially different final tree topologies (topological difference exceeding 10 %) for approximately 5 % of the tree inferences conducted on the 39 empirical datasets used in our study. Conclusions: We find that, using the best-fit nucleotide substitution model may change the final ML tree topology compared to an inference under a default GTR model. The effect is less pronounced when comparing distinct information criteria. Nonetheless, in some cases we did obtain substantial topological differences