Working memory capacity and arithmetic achievement in kindergarten and primary school

Mithilfe von drei Studien wurde untersucht wie die frühe arithmetische Leistungsfähigkeit von der Arbeitsgedächtniskapazität beeinflusst wird. In allen Studien wurde das Arbeitsgedächtnismodell von Baddeley (1986) genutzt, welches aus drei Komponenten, nämlich der zentralen Exekutive als Kontrolleinheit, sowie den beiden untergeordneten Speichersystemen, der phonologischen Schleife und dem visuell-räumlichen Skizzenblock besteht. Der genaue Einfluss dieser Komponenten auf die frühe Arithmetik kann jedoch noch nicht vollständig erklärt werden, da es in der Forschung teilweise zu widersprüchlichen Ergebnissen kommt. In dieser Publikation soll die Frage in den Blick genommen werden, ob sich die Korrelation zwischen Arbeitsgedächtniskapazität und arithmetischer Leistungsfähigkeit als Funktion des Alters, der arithmetischen Problemstellung oder der Gruppenzugehörigkeit zu bestimmten arithmetischen Leistungsgruppen ändert. Die aktuelle Forschung zeigt in Bezug auf die zentrale Exekutive, dass viele arithmetische Probleme im Kindergartenbereich noch nicht hinreichend komplex sind, um diese überhaupt nutzen zu müssen (Espy et al., 2004). Andererseits benötigen auch Kinder die mathematische Fähigkeiten bereits vollständig automatisiert haben kaum noch die zentrale Exekutive, sondern eher die reinen Speichersysteme (de Smedt et al., 2009, Meyer et al., 2009). Zusammengefasst ist die zentrale Exekutive damit vor allem für neue, nicht automatisierte und hinreichend komplexe Probleme vonnöten. Das heißt aber auch, dass dieselben mathematischen Problemstellungen im jungen Alter auf zentralexekutive Kapazitäten zugreifen können, während dies später nicht mehr der Fall sein muss. In Bezug auf die Subsysteme zeigen sich ähnliche Befunde mit Bezug zum Alter. So konnten de Smedt et al. (2009) zeigen, dass der Einfluss des visuell-räumlichen Arbeitsgedächtnisses von der ersten zur zweiten Klasse abnimmt, während gleichzeitig stärker auf phonologische Ressourcen zurückgegriffen wurde. Dies wird von ihnen mit einem Wechsel von einfachen Zählstrategien (z.B. Fingernutzung) zu verbalen Strategien interpretiert. Wie bereits erwähnt wurde, müssen Probleme hinreichend neu und komplex sein um zentralexekutive Aktivität auszulösen, was in direktem Zusammenhang mit der zweiten zu untersuchenden Variable, nämlich den unterschiedlichen arithmetischen Problemstellungen steht. Andersson (2008) konnte zeigen, dass Teil-Teil-Ganze Aufgaben (61 + __ = 73) visuell-räumliche Kapazität nutzen, da diese Probleme durch ein ‚Umarrangieren‘ der Aufgabe leichter gelöst werden können. Andererseits benötigen normale Additionsaufgaben (61 +12 = __) diese Fähigkeit nicht und können allein durch verbales Rekodieren und damit die phonologische Schleife gelöst werden. In Bezug auf unsere dritte Frage wollten wir vor allem herausfinden ob sich Kinder mit Problemen im arithmetischen Bereich von solchen ohne diese Probleme in Bezug auf ihre Arbeitsgedächtnisnutzung unterscheiden. In Studie 1 wurden Kindergarten und Grundschulkinder auf ihr Wissen um basale arithmetische Konzepte nach dem Modell von Fritz und Ricken (2008) getestet. Basierend auf diesen Ergebnissen wurden sie in zwei Gruppen gleicher arithmetischer Leistung aufgeteilt. Die eine Gruppe zeigte jedoch altersangemessene Leistung, während die andere zwar dieselbe absolute Leistung zeigte, jedoch aufgrund ihres größeren Alters altersverzögerte Leistungen zeigte. Anschließend wurden sowohl die Arbeitsgedächtniskapazität als auch die arithmetische Leistungsfähigkeit noch einmal detaillierter erfasst. Mithilfe von Regressionsanalysen wurde festgestellt, dass für die gesamte Stichprobe sowohl die zentrale Exekutive, als auch der visuell-räumliche Skizzenblock arithmetische Leistungen vorhersagten, selbst wenn Intelligenz, phonologische Bewusstheit, Naming Speed und Alter als Kontrollvariablen eingesetzt wurden. Darüber hinaus gab es keine Mittelwertsunterschiede im Bereich der Arbeitsgedächtniskapazität zwischen den beiden Gruppen. Es konnte jedoch nachgewiesen werden, dass der visuell-räumliche Skizzenblock lediglich für die durchschnittlich entwickelten Kinder prädiktiven Wert hatte, nicht aber für jene mit altersverzögerten Leistungen. Dies wird als Nutzungsdefizit interpretiert, da die Kinder über die notwendigen Kapazitäten verfügen, aber nicht in der Lage sind diese zielführend zur Lösung arithmetischer Probleme einzusetzen. In Studie 2 wurde die arithmetische Leistung basierend auf dem Modell der beiden Kernsysteme nach Feigenson et al. (2004), sowie die Arbeitsgedächtniskapazität zu Beginn der ersten Klasse, sowie die schulische Leistung zu Beginn der zweiten Klasse erfasst. Es sollte untersucht werden, ob Kernsysteme und Arbeitsgedächtnis in einem Zusammenhang stehen und wie sich der prädiktive Wert für spätere Schulleistung darstellt. Es konnte gezeigt werden, dass die Kernsysteme weitestgehend unabhängig vom Arbeitsgedächtnis funktionieren, da dieses kein Prädiktor für diese Leistungen war. Für die Schulleistungen hingegen zeigte sich, dass vor allem die zentrale Exekutive in diesem Alter wesentlichen Einfluss hat. Diese Befunde decken sich mit denen von Bull et al. (2008), die festgestellt haben, dass die zentrale Exekutive für fast alle Lernprozesse in diesem Alter verantwortlich ist. In Studie 3 wurde die Arbeitsgedächtniskapazität, die mathematische Leistungsfähigkeit sowie die Lesegeschwindigkeit von Zweit-, Dritt- und Viertklässlern erhoben um herauszufinden ob der Einfluss des Arbeitsgedächtnisses sich über das Alter verändert. Es konnte gezeigt werden, dass insbesondere die Lesegeschwindigkeit im jüngeren Einfluss einen stärkeren Einfluss auf die mathematischen Leistungen hatte, welche sie im höheren Alter an die phonologische Schleife verliert. Darüber hinaus konnte auf einem deskriptiven Niveau gezeigt werden, dass der Einfluss der zentralen Exekutive und des visuell-räumlichen Skizzenblockes mit steigendem Alter abnimmt. Zu Beginn der Grundschulzeit scheinen selbst einfache Aufgaben dual-task Anforderungen an die Schülerinnen und Schüler zu stellen, da gleichzeitig gelesen und gerechnet werden muss. Mit besseren – und zumindest für einfache mathematische Aufgabe ausreichenden – Fähigkeiten im Bereich des Lesens verschwindet diese Anforderung an die zentrale Exekutive, so dass wieder die Speichersysteme im Vordergrund stehen.Three studies were conducted to investigate how working memory capacity influences early arithmetic skills. We used the working memory model of Baddeley (1986) as it is most commonly used in research. This model consists of three components, namely the central executive as a control unit alongside the phonological loop and the visuo-spatial sketchpad as two subsidiary modal storage units. However, the specific influence of these components on early arithmetic is not fully understood yet, as research often generates inconsistent results. In this publication we wanted to focus the question whether the correlation between working memory capacity and arithmetic skills changes as a function of age, arithmetic problems used or group affiliation to different arithmetic ability groups. Current research regarding central executive influence shows that arithmetic problems used in the kindergarten are not complex enough to trigger the influence of central executive resources (Espy et al., 2004). On the other hand studies show that children automatize many mathematical abilities and thus only rely on the subsidiary storage systems but not the central executive (de Smedt et al., 2009, Meyer et al., 2009). It seems central executive capacity is only used with new – not automatized – and complex problems. This means that the same problem may trigger central executive resources at a young, but not at an older age. Similar results can be found for the storage systems. For example, de Smedt et al. (2009) were able to show that the influence of visuo-spatial working memory fades from first to second class, while phonological resources are used more commonly. They attributed this finding to a shift from finger usage into more verbal strategies while solving math problems. As mentioned before, problems have to be new and complex to trigger central executive activity, which leads us to our second variable, different arithmetic problems. Andersson (2008), for example, showed that part-part-whole problems (61 + __ = 73) rely on visuo-spatial resources as those problems have to be rearranged into other types of problems to be solve. However, ‘common’ addition problems (61 +12 = __) just need verbal coding and thus rely on the phonological loop. Our third question regarded children with different arithmetic proficiency. We wanted to find out whether children who do average on arithmetic differ from those who perform under par in terms of working memory. In study 1 we screened kindergarten and primary school students for their knowledge of arithmetic concepts based on the model of Fritz and Ricken (2008). Based on these results we composed one group with children of age-appropriate arithmetic skills and matched a second group with similar test scores but of older age. Afterwards we assessed working memory capacity and arithmetic skills in more detail. We conducted regression analyses for the entire sample and found, that central executive, as well as visuo-spatial capacity predicted arithmetic skills, even when controlling for intelligence, phonological awareness, naming speed and age. We did not find differences in working memory capacity between our two groups. However, we found that the visuo-spatial sketchpad was a significant predictor of arithmetic skills only for average children, but not for those with age-inappropriate skill levels. This is interpreted as a usage-deficit, as those children have certain capacities, but make no use of them when solving arithmetic problems. In study 2 we assessed arithmetic skills based on the core system model of Feigenson et al. (2004), as well as working memory capacity alongside other control variables at the very beginning of first grade and school mathematics at the beginning of second grade. We wanted to test whether core system based skills are correlated with working memory capacity and if so, whether they predict later school success. To our knowledge there has been no research in this field yet. We found that core system based skills seem to be largely independent from working memory, as working memory did not predict children’s abilities. However, the central executive alongside core system based skills predicted later school success. In line with current research (Bull et al., 2008) we interpret this as a sign that central executive capacity is needed for all learning processes at this age. In study 3 we assessed school arithmetic and reading speed of children from second to fourth grade, as well as their working memory capacity to find out whether working memory influence differs as a function of age. We found that the influence of reading speed on arithmetic gets lower over the course of the grades, while the influence of phonological loop capacity gets larger. Furthermore, on a descriptive level we found that central executive and visuo-spatial sketchpad capacity diminishes with higher grades, although these findings did not reach statistical significance. At the beginning of primary school children seem to rely on newly acquired reading skills which impose dual-task difficulties on them when solving math problems, as they have to read numbers and arithmetic symbols, while solving the problem at the same time. This difficulties diminish when children get better at reading – at least at reading mathematically – which explains why central executive influence gets lower at higher grades, while the subsystems play a stronger role

Импортозамещение в энергетике

В статье рассматривается зависимость отраслей ТЭК России от импортного оборудования и предлагаются конкретные механизмы как максимально эффективно, обеспечить дальнейшее устойчивое развитие ТЭК с учётом технологических потребностей

β2-Adrenoceptor Deficiency Results in Increased Calcified Cartilage Thickness and Subchondral Bone Remodeling in Murine Experimental Osteoarthritis

Purpose: Recent studies demonstrated a contribution of adrenoceptors (ARs) to osteoarthritis (OA) pathogenesis. Several AR subtypes are expressed in joint tissues and the β2-AR subtype seems to play a major role during OA progression. However, the importance of β2-AR has not yet been investigated in knee OA. Therefore, we examined the development of knee OA in β2-AR-deficient (Adrb2-/- ) mice after surgical OA induction. Methods: OA was induced by destabilization of the medial meniscus (DMM) in male wildtype (WT) and Adrb2-/- mice. Cartilage degeneration and synovial inflammation were evaluated by histological scoring. Subchondral bone remodeling was analyzed using micro-CT. Osteoblast (alkaline phosphatase - ALP) and osteoclast (cathepsin K - CatK) activity were analyzed by immunostainings. To evaluate β2-AR deficiency-associated effects, body weight, sympathetic tone (splenic norepinephrine (NE) via HPLC) and serum leptin levels (ELISA) were determined. Expression of the second major AR, the α2-AR, was analyzed in joint tissues by immunostaining. Results: WT and Adrb2-/- DMM mice developed comparable changes in cartilage degeneration and synovial inflammation. Adrb2-/- DMM mice displayed elevated calcified cartilage and subchondral bone plate thickness as well as increased epiphyseal BV/TV compared to WTs, while there were no significant differences in Sham animals. In the subchondral bone of Adrb2-/- mice, osteoblasts activity increased and osteoclast activity deceased. Adrb2-/- mice had significantly higher body weight and fat mass compared to WT mice. Serum leptin levels increased in Adrb2-/- DMM compared to WT DMM without any difference between the respective Shams. There was no difference in the development of meniscal ossicles and osteophytes or in the subarticular trabecular microstructure between Adrb2-/- and WT DMM as well as Adrb2-/- and WT Sham mice. Number of α2-AR-positive cells was lower in Adrb2-/- than in WT mice in all analyzed tissues and decreased in both Adrb2-/- and WT over time. Conclusion: We propose that the increased bone mass in Adrb2-/- DMM mice was not only due to β2-AR deficiency but to a synergistic effect of OA and elevated leptin concentrations. Taken together, β2-AR plays a major role in OA-related subchondral bone remodeling and is thus an attractive target for the exploration of novel therapeutic avenues

LSST: from Science Drivers to Reference Design and Anticipated Data Products

(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta<+34.5^\circ$, and will be imaged multiple times in six bands, $ugrizy$, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg$^2$ region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to $r\sim27.5$. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

The Sex-Specific Impact of Meiotic Recombination on Nucleotide Composition

Meiotic recombination is an important evolutionary force shaping the nucleotide landscape of genomes. For most vertebrates, the frequency of recombination varies slightly or considerably between the sexes (heterochiasmy). In humans, male, rather than female, recombination rate has been found to be more highly correlated with the guanine and cytosine (GC) content across the genome. In the present study, we review the results in human and extend the examination of the evolutionary impact of heterochiasmy beyond primates to include four additional eutherian mammals (mouse, dog, pig, and sheep), a metatherian mammal (opossum), and a bird (chicken). Specifically, we compared sex-specific recombination rates (RRs) with nucleotide substitution patterns evaluated in transposable elements. Our results, based on a comparative approach, reveal a great diversity in the relationship between heterochiasmy and nucleotide composition. We find that the stronger male impact on this relationship is a conserved feature of human, mouse, dog, and sheep. In contrast, variation in genomic GC content in pig and opossum is more strongly correlated with female, rather than male, RR. Moreover, we show that the sex-differential impact of recombination is mainly driven by the chromosomal localization of recombination events. Independent of sex, the higher the RR in a genomic region and the longer this recombination activity is conserved in time, the stronger the bias in nucleotide substitution pattern, through such mechanisms as biased gene conversion. Over time, this bias will increase the local GC content of the region

Multiple melting stages and refertilization as indicators for ridge to subduction formation: The New Caledonia ophiolite

International audienceThe origin of the New Caledonia ophiolite (South West Pacific), one of the largest in the world, is controversial. This nappe of ultramafic rocks (300 km long, 50 km wide and 2 km thick) is thrust upon a smaller nappe (Poya terrane) composed of basalts from mid-ocean ridges (MORB), back arc basins (BABB) and ocean islands (OIB). This nappe was tectonically accreted from the subducting plate prior and during the obduction of the ultramafic nappe. The bulk of the ophiolite is composed of highly depleted harzburgites (± dunites) with characteristic U-shaped bulk-rock rare-earth element (REE) patterns that are attributed to their formation in a forearc environment. In contrast, the origin of spoon-shaped REE patterns of lherzolites in the northernmost klippes was unclear. Our new major element and REE data on whole rocks, spinel and clinopyroxene establish the abyssal affinity of these lherzolites. Significant LREE enrichment in the lherzolites is best explained by partial melting in a spreading ridge, followed by near in-situ refertilization from deeper mantle melts. Using equilibrium melting equations, we show that melts extracted from these lherzolites are compositionally similar to the MORB of the Poya terrane. This is used to infer that the ultramafic nappe and the mafic Poya terrane represent oceanic lithosphere of a single marginal basin that formed during the late Cretaceous. In contrast, our spinel data highlights the strong forearc affinities of the most depleted harzburgites whose compositions are best modeled by hydrous melting of a source that had previously experienced depletion in a spreading ridge. The New Caledonian boninites probably formed during this second stage of partial melting. The two melting events in the New Caledonia ophiolite record the rapid transition from oceanic accretion to convergence in the South Loyalty Basin during the Late Paleocene, with initiation of a new subduction zone at or near the ridge axis

Common variation in PHACTR1 is associated with susceptibility to cervical artery dissection

Cervical artery dissection (CeAD), a mural hematoma in a carotid or vertebral artery, is a major cause of ischemic stroke in young adults although relatively uncommon in the general population (incidence of 2.6/100,000 per year). Minor cervical traumas, infection, migraine and hypertension are putative risk factors, and inverse associations with obesity and hypercholesterolemia are described. No confirmed genetic susceptibility factors have been identified using candidate gene approaches. We performed genome-wide association studies (GWAS) in 1,393 CeAD cases and 14,416 controls. The rs9349379[G] allele (PHACTR1) was associated with lower CeAD risk (odds ratio (OR) = 0.75, 95% confidence interval (CI) = 0.69-0.82; P = 4.46 × 10(-10)), with confirmation in independent follow-up samples (659 CeAD cases and 2,648 controls; P = 3.91 × 10(-3); combined P = 1.00 × 10(-11)). The rs9349379[G] allele was previously shown to be associated with lower risk of migraine and increased risk of myocardial infarction. Deciphering the mechanisms underlying this pleiotropy might provide important information on the biological underpinnings of these disabling conditions

Mild-to-Moderate Kidney Dysfunction and Cardiovascular Disease: Observational and Mendelian Randomization Analyses

BACKGROUND: End-stage renal disease is associated with a high risk of cardiovascular events. It is unknown, however, whether mild-to-moderate kidney dysfunction is causally related to coronary heart disease (CHD) and stroke. METHODS: Observational analyses were conducted using individual-level data from 4 population data sources (Emerging Risk Factors Collaboration, EPIC-CVD [European Prospective Investigation into Cancer and Nutrition-Cardiovascular Disease Study], Million Veteran Program, and UK Biobank), comprising 648 135 participants with no history of cardiovascular disease or diabetes at baseline, yielding 42 858 and 15 693 incident CHD and stroke events, respectively, during 6.8 million personyears of follow-up. Using a genetic risk score of 218 variants for estimated glomerular filtration rate (eGFR), we conducted Mendelian randomization analyses involving 413 718 participants (25917 CHD and 8622 strokes) in EPIC-CVD, Million Veteran Program, and UK Biobank. RESULTS: There were U-shaped observational associations of creatinine-based eGFR with CHD and stroke, with higher risk in participants with eG FR values 105 mL.min(-1).1.73 m(-2), compared with those with eG FR between 60 and 105 mL.min(-1).1.73 m(-2). Mendelian randomization analyses for CHD showed an association among participants with eGFR 105 mL.min(-1).1.73 m(-2). Results were not materially different after adjustment for factors associated with the eGFR genetic risk score, such as lipoprotein(a), triglycerides, hemoglobin Alc, and blood pressure. Mendelian randomization results for stroke were nonsignificant but broadly similar to those for CHD. CONCLUSIONS: In people without manifest cardiovascular disease or diabetes, mild-to-moderate kidney dysfunction is causally related to risk of CHD, highlighting the potential value of preventive approaches that preserve and modulate kidney function

Functional mechanisms underlying pleiotropic risk alleles at the 19p13.1 breast-ovarian cancer susceptibility locus

A locus at 19p13 is associated with breast cancer (BC) and ovarian cancer (OC) risk. Here we analyse 438 SNPs in this region in 46,451 BC and 15,438 OC cases, 15,252 BRCA1 mutation carriers and 73,444 controls and identify 13 candidate causal SNPs associated with serous OC (P=9.2 × 10-20), ER-negative BC (P=1.1 × 10-13), BRCA1-associated BC (P=7.7 × 10-16) and triple negative BC (P-diff=2 × 10-5). Genotype-gene expression associations are identified for candidate target genes ANKLE1 (P=2 × 10-3) and ABHD8 (P<2 × 10-3). Chromosome conformation capture identifies interactions between four candidate SNPs and ABHD8, and luciferase assays indicate six risk alleles increased transactivation of the ADHD8 promoter. Targeted deletion of a region containing risk SNP rs56069439 in a putative enhancer induces ANKLE1 downregulation; and mRNA stability assays indicate functional effects for an ANKLE1 3′-UTR SNP. Altogether, these data suggest that multiple SNPs at 19p13 regulate ABHD8 and perhaps ANKLE1 expression, and indicate common mechanisms underlying breast and ovarian cancer risk

Breast cancer risk variants at 6q25 display different phenotype associations and regulate ESR1, RMND1 and CCDC170.

We analyzed 3,872 common genetic variants across the ESR1 locus (encoding estrogen receptor α) in 118,816 subjects from three international consortia. We found evidence for at least five independent causal variants, each associated with different phenotype sets, including estrogen receptor (ER(+) or ER(-)) and human ERBB2 (HER2(+) or HER2(-)) tumor subtypes, mammographic density and tumor grade. The best candidate causal variants for ER(-) tumors lie in four separate enhancer elements, and their risk alleles reduce expression of ESR1, RMND1 and CCDC170, whereas the risk alleles of the strongest candidates for the remaining independent causal variant disrupt a silencer element and putatively increase ESR1 and RMND1 expression.This is the author accepted manuscript. The final version is available from Nature Publishing Group via http://dx.doi.org/10.1038/ng.352