Isotopic evidence for volatile replenishment of the Moon during the Late Accretion

The traditional view of a dry, volatile-poor Moon has been challenged by the identification of water and other volatiles in lunar samples, but the volatile budget delivery time(s), source(s) and temporal evolution remain poorly constrained. Here we show that hydrogen and chlorine isotopic ratios in lunar apatite changed significantly during the Late Accretion (LA, 4.1–3.8 billion years ago). During this period, deuterium/hydrogen ratios in the Moon changed from initial carbonaceous-chondrite-like values to values consistent with an influx of ordinary-chondrite-like material and pre-LA elevated δ³⁷Cl values drop towards lower chondrite-like values. Inferred pre-LA lunar interior water contents are significantly lower than pristine values suggesting degassing, followed by an increase during the LA. These trends are consistent with dynamic models of solar-system evolution, suggesting that the Moon''s (and Earth''s) initial volatiles were replenished ∼0.5 Ga after their formation, with their final budgets reflecting a mixture of sources and delivery times.     

Distributed delay input shaper design by optimizing smooth kernel functions

The aim of this paper is the development of a general class of input shapers with distributed time delay which leads to retarded spectral properties. The design of the shaper is formulated as a multi-objective optimization problem, where response time and robustness, expressed in terms of residual vibrations, are the main objectives. As a part of the optimization formulation, common requirements for input shapers such as non-decreasing step response and unity steady state gain are considered in the design. Moreover, additional optional requirements, such as smoothness of a step response, jerk and even jounce limits can be added to optimization procedure. The resulting problem can be solved using convex optimization techniques. Several illustrative examples are presented in comparison with classical input shaping techniques. Finally, implementation aspects are discussed. The paper is accompanied by an implementation in MATLAB, including a user-friendly interface for the interactive shaper design.     

The prevalence of poor reading in Dutch special elementary education

The relative frequency of poor readers in Dutch general elementary education (GEE) and special elementary education (SEE) and the characteristics of their reading performance were investigated using a lexical decision procedure. According to the same norms that identified 9% of students as poor readers in GEE, no less than 73% of the students in SEE were classified as poor readers. On average, the GEE poor readers were better readers than those in SEE, but the findings do not point to substantial differences in reading processes between the two reader groups. Hypotheses about the nature of the referral process that may cause this surprisingly strong relation between poor reading ability and SEE placement are advanced.     

A Case Study in the Measurement of Educational Efficiency in Open and Distance Learning

Open and distance learning (ODL) gives learners control of the time, place, and pace of learning, often being characterized as flexible learning. However, this flexibility goes hand‐in‐hand with procrastination and non‐completion. As a result, the efficiency of the educational process is of importance to ODL providers, government funding agencies, and learners themselves. Despite its importance, measuring efficiency in ODL is problematic. This article presents a case study in measuring educational efficiency using a method which reflects the special characteristics of ODL. The article concludes with a discussion of the wider applicability of the measurement method in the context of lifelong learning.     

Regional inequality in reading performance: an exploration in Belgium

In the 2009 Programme for International Student Assessment, the Flemish community of Belgium outscored its French community in reading, with low achievers accounting for a large proportion of the score gaps. In this study, between-community comparisons based on the Blinder-Oaxaca decomposition method showed that the Flemish community benefits largely from its policies and practices of giving schools relative autonomy in resource allocation, promoting good student conduct, and decreasing grade retention. Between-community comparisons using the Juhn-Murphy-Pierce decomposition method showed that compared to their Flemish peers in the same percentile, low achievers in the French community are hindered more by their relatively low grade level; disadvantageous school economic, social, and cultural composition; and negative school supportive climate while medium and high achievers benefit more from their advantageous school economic, social, and cultural composition; positive supportive climate; and high proportion of qualified teachers in schools.     

Local Observed‐Score Kernel Equating

Three local observed‐score kernel equating methods that integrate methods from the local equating and kernel equating frameworks are proposed. The new methods were compared with their earlier counterparts with respect to such measures as bias—as defined by Lord's criterion of equity—and percent relative error. The local kernel item response theory observed‐score equating method, which can be used for any of the common equating designs, had a small amount of bias, a low percent relative error, and a relatively low kernel standard error of equating, even when the accuracy of the test was reduced. The local kernel equating methods for the nonequivalent groups with anchor test generally had low bias and were quite stable against changes in the accuracy or length of the anchor test. Although all proposed methods showed small percent relative errors, the local kernel equating methods for the nonequivalent groups with anchor test design had somewhat larger standard error of equating than their kernel method counterparts.     

Testing elementary and secondary school students’ ability to perform historical perspective taking: the constructing of valid and reliable measure instruments

Historical reasoning competencies play an important role in history education. However, valid and reliable large-scale measurement instruments to assess these competencies are scarce. This study considers two instruments for measuring students’ ability to perform historical perspective taking (HPT) as a historical reasoning competency. The instruments have been tested for validity and reliability among 1,270 Dutch upper elementary and secondary school students, ranging in age from 10 to 17 years. One instrument offers effective validity and reliability and can map HPT performance among a large and heterogeneous student population. The results show that even upper elementary school students are capable of performing HPT. However, as students age, their ability to perform HPT increases. Differences regarding the ability to perform HPT were also found between educational levels. Pre-university students performed HPT more successfully compared to students at lower educational levels. The results of this study can be used to gain insight into the construct of HPT and into how historical reasoning competencies such as HPT can be measured. Furthermore, the results provide insight into how differences between students, such as age and educational levels, influence the performance of HPT.     

Optimal cognitive distance and absorptive capacity

In this paper we test the relation between cognitive distance and innovation performance of firms engaged in technology-based alliances. The key finding is that the hypothesis of an inverted U-shaped effect of cognitive distance on innovation performance of firms is confirmed. Moreover, as expected, we found that the positive effect for firms is much higher when engaging in more radical, exploratory alliances than in more exploitative alliances. The effect of cumulative R&D turns out to be mixed. It appears to increase absorptive capacity, as expected, but there is clear evidence that it also reduces the effect of cognitive distance on novelty value, making it increasingly difficult to find additional novelty.     

Testing the Intervention Effect in Single-Case Experiments: A Monte Carlo Simulation Study

This article reports on a Monte Carlo simulation study, evaluating two approaches for testing the intervention effect in replicated randomized AB designs: two-level hierarchical linear modeling (HLM) and using the additive method to combine randomization test p values (RTcombiP). Four factors were manipulated: mean intervention effect, number of cases included in a study, number of measurement occasions for each case, and between-case variance. Under the simulated conditions, Type I error rate was under control at the nominal 5% level for both HLM and RTcombiP. Furthermore, for both procedures, a larger number of combined cases resulted in higher statistical power, with many realistic conditions reaching statistical power of 80% or higher. Smaller values for the between-case variance resulted in higher power for HLM. A larger number of data points resulted in higher power for RTcombiP.