Working memory refers to a mental workspace, involved in controlling, regulating, and actively maintaining relevant information to accomplish complex cognitive tasks (e.g. mathematical processing). ...Despite the potential relevance of a relation between working memory and math for understanding developmental and individual differences in mathematical skills, the nature of this relationship is not well-understood. This paper reviews four approaches that address the relation of working memory and math: 1) dual task studies establishing the role of working memory during on-line math performance; 2) individual difference studies examining working memory in children with math difficulties; 3) studies of working memory as a predictor of mathematical outcomes; and 4) longitudinal studies of working memory and math. The goal of this review is to evaluate current information on the nature of the relationship between working memory and math provided by these four approaches, and to present some of the outstanding questions for future research.
HIV-1 reservoirs preclude virus eradication in patients receiving highly active antiretroviral therapy (HAART). The best characterized reservoir is a small, difficult-to-quantify pool of resting ...memory CD4(+) T cells carrying latent but replication-competent viral genomes. Because strategies targeting this latent reservoir are now being tested in clinical trials, well-validated high-throughput assays that quantify this reservoir are urgently needed. Here we compare eleven different approaches for quantitating persistent HIV-1 in 30 patients on HAART, using the original viral outgrowth assay for resting CD4(+) T cells carrying inducible, replication-competent viral genomes as a standard for comparison. PCR-based assays for cells containing HIV-1 DNA gave infected cell frequencies at least 2 logs higher than the viral outgrowth assay, even in subjects who started HAART during acute/early infection. This difference may reflect defective viral genomes. The ratio of infected cell frequencies determined by viral outgrowth and PCR-based assays varied dramatically between patients. Although strong correlations with the viral outgrowth assay could not be formally excluded for most assays, correlations achieved statistical significance only for integrated HIV-1 DNA in peripheral blood mononuclear cells and HIV-1 RNA/DNA ratio in rectal CD4(+) T cells. Residual viremia was below the limit of detection in many subjects and did not correlate with the viral outgrowth assays. The dramatic differences in infected cell frequencies and the lack of a precise correlation between culture and PCR-based assays raise the possibility that the successful clearance of latently infected cells may be masked by a larger and variable pool of cells with defective proviruses. These defective proviruses are detected by PCR but may not be affected by reactivation strategies and may not require eradication to accomplish an effective cure. A molecular understanding of the discrepancy between infected cell frequencies measured by viral outgrowth versus PCR assays is an urgent priority in HIV-1 cure research.
The association between the host immune environment and the size of the HIV reservoir during effective antiretroviral therapy is not clear. Progress has also been limited by the lack of a ...well-accepted assay for quantifying HIV during therapy. We examined the association between multiple measurements of HIV and T cell activation (as defined by markers including CD38, HLA-DR, CCR5 and PD-1) in 30 antiretroviral-treated HIV-infected adults. We found a consistent association between the frequency of CD4+ and CD8+ T cells expressing HLA-DR and the frequency of resting CD4+ T cells containing HIV DNA. This study highlights the need to further examine this relationship and to better characterize the biology of markers commonly used in HIV studies. These results may also have implications for reactivation strategies.
The precise role of CD4 T cell turnover in maintaining HIV persistence during antiretroviral therapy (ART) has not yet been well characterized. In resting CD4 T cell subpopulations from 24 ...HIV-infected ART-suppressed and 6 HIV-uninfected individuals, we directly measured cellular turnover by heavy water labeling, HIV reservoir size by integrated HIV-DNA (intDNA) and cell-associated HIV-RNA (caRNA), and HIV reservoir clonality by proviral integration site sequencing. Compared to HIV-negatives, ART-suppressed individuals had similar fractional replacement rates in all subpopulations, but lower absolute proliferation rates of all subpopulations other than effector memory (TEM) cells, and lower plasma IL-7 levels (p = 0.0004). Median CD4 T cell half-lives decreased with cell differentiation from naïve to TEM cells (3 years to 3 months, p<0.001). TEM had the fastest replacement rates, were most highly enriched for intDNA and caRNA, and contained the most clonal proviral expansion. Clonal proviruses detected in less mature subpopulations were more expanded in TEM, suggesting that they were maintained through cell differentiation. Earlier ART initiation was associated with lower levels of intDNA, caRNA and fractional replacement rates. In conclusion, circulating integrated HIV proviruses appear to be maintained both by slow turnover of immature CD4 subpopulations, and by clonal expansion as well as cell differentiation into effector cells with faster replacement rates.
Results from a 2-year longitudinal study of 181 children from 4th through 5th grade are reported. Levels of growth in children's computation, word problem, and estimation skills by means of common ...fractions were predicted by working memory, attentive classroom behavior, conceptual knowledge about fractions, and simple arithmetic fluency. Comparisons of 55 participants identified as having mathematical difficulties to those without mathematical difficulties revealed that group differences in emerging fraction skills were consistently mediated by attentive classroom behavior and conceptual knowledge about fractions. Neither working memory nor arithmetic fluency mediated group differences in growth in fraction skills. It was also found that the development of basic fraction skills and conceptual knowledge are bidirectional in that conceptual knowledge exerted strong influences on all 3 types of basic fraction skills, and basic fraction skills exerted a more modest influence on subsequent conceptual knowledge. Results are discussed with reference to how the identification of potentially malleable student characteristics that contribute to the difficulties that some students have with fractions informs interventions. Also, results will contribute to a future theoretical account concerning how domain-general and domain-specific factors influence the development of basic fraction skills.
Posttreatment controllers (PTCs) are rare HIV-infected individuals who can limit viral rebound after antiretroviral therapy interruption (ATI), but the mechanisms of this remain unclear. To ...investigate these mechanisms, we quantified various HIV RNA transcripts (via reverse transcription droplet digital PCR RT-ddPCR) and cellular transcriptomes (via RNA-seq) in blood cells from PTCs and noncontrollers (NCs) before and two time points after ATI. HIV transcription initiation did not significantly increase after ATI in PTCs or in NCs, whereas completed HIV transcripts increased at early ATI in both groups and multiply-spliced HIV transcripts increased only in NCs. Compared to NCs, PTCs showed lower levels of HIV DNA, more cell-associated HIV transcripts per total RNA at all times, no increase in multiply-spliced HIV RNA at early or late ATI, and a reduction in the ratio of completed/elongated HIV RNA after early ATI. NCs expressed higher levels of the IL-7 pathway before ATI and expressed higher levels of multiple cytokine, inflammation, HIV transcription, and cell death pathways after ATI. Compared to the baseline, the NCs upregulated interferon and cytokine (especially TNF) pathways during early and late ATI, whereas PTCs upregulated interferon and p53 pathways only at early ATI and downregulated gene translation during early and late ATI. In NCs, viral rebound after ATI is associated with increases in HIV transcriptional completion and splicing, rather than initiation. Differences in HIV and cellular transcription may contribute to posttreatment control, including an early limitation of spliced HIV RNA, a delayed reduction in completed HIV transcripts, and the differential expression of the IL-7, p53, and TNF pathways.
The findings presented here provide new insights into how HIV and cellular gene expression change after stopping ART in both noncontrollers and posttreatment controllers. Posttreatment control is associated with an early ability to limit increases in multiply-spliced HIV RNA, a delayed (and presumably immune-mediated) ability to reverse an initial rise in processive/completed HIV transcripts, and multiple differences in cellular gene expression pathways. These differences may represent correlates or mechanisms of posttreatment control and may provide insight into the development and/or monitoring of therapeutic strategies that are aimed at a functional HIV cure.
External procedural justice in police–citizen interactions has been found to have a relationship with cooperation, compliance, and police legitimacy. The individual dimensions of organizational ...justice comprised of distributive, procedural, interpersonal, and informational justice, have been less frequently examined. Organizational justice has been found to be associated with many desirable outcomes both within policing and in other professions. This study utilized a convenience sample (n = 106) of police officers from five school district police departments in the Houston, Texas metropolitan area. The study combined two sections of two existing instruments for the purpose of examining the extent to which officer perceptions of the four dimensions of organizational justice contribute to officer perceptions of external procedural justice in police–citizen interactions. Results indicated officers rated themselves very highly on the levels of external procedural justice they demonstrated with the public. Officers rated their supervisors highest in the interpersonal justice dimension of organizational justice. Surprisingly, no significant associations emerged between any of the four dimensions of organizational justice and external procedural justice. The findings of this study were inconsistent with the majority of extant research which found that organizational justice correlates with and predicts external procedural justice. This study indicated that officers may overestimate their own utilization of external procedural justice. In addition, it suggests the four dimensions of organizational justice may not predict external procedural justice and raises questions regarding the relationship between these two variables.
► In this study we compare relative performance in two kinds of knowledge concerning fractions. ► Measures of conceptual and procedural knowledge were obtained. ► Cluster analysis identified several ...patterns of strengths and weaknesses. ► We conclude that prior conflicting results can be explained by our findings.
The purpose of this study was to explore individual patterns of strengths and weaknesses in children’s mathematical knowledge about common fractions. Tasks that primarily measure either conceptual or procedural aspects of mathematical knowledge were assessed with the same children in their fourth- and fifth-grade years (
N
=
181, 56% female and 44% male). Procedural knowledge was regressed on levels of conceptual knowledge, and vice versa, to obtain residual scores. Residual scores capture variability in each kind of math knowledge that is not shared with the other type of knowledge. Cluster analysis using residuals indicated four distinct knowledge profiles in fourth graders: (a) higher than expected conceptual knowledge and relatively lower procedural knowledge, (b) relatively lower conceptual knowledge and higher procedural knowledge, (c) lower concepts but expected levels of procedural knowledge, and (d) relatively higher than expected levels of both procedural and conceptual knowledge. In fifth grade, another cluster emerged that showed lower procedures but expected levels of conceptual knowledge. In general, students with relatively lower than expected conceptual knowledge showed poorer accuracy on measures used to form the clusters and also word problem setups and estimation of sums. Implications for explaining seemingly conflicting results from prior work across studies are discussed.
The home literacy environment (HLE) is an important variable in the development of a number of developmental and educational outcomes; however, a number of questions concerning its conceptualization ...and relations to diverse outcomes are unanswered. This study examined the relations of six different conceptualizations of the HLE to oral language, phonological sensitivity, and early literacy development in a longitudinal sample of 115 preschoolers. Multiple regression and correlational analyses indicated that each of the HLE conceptualizations was consistently related to the outcomes studied. However, the magnitude of the relations varied considerably across outcomes and when other developmental predictors were taken into account. These results indicate that future examinations of the HLE and its role in the development of language and literacy skills need to take into account the manner in which the home environment is conceptualized. /// Spanish El contexto de alfabetización del hogar (HLE) es una variable importante en el desarrollo de una cantidad de consecuencias evolutivas y educativas; sin embargo hay un gran número de interrogantes sin respuesta referidos a su conceptualización y relaciones con los diversos efectos. Este estudio examinó las relaciones de seis conceptualizaciones diferentes del HLE con el lenguaje oral, la sensibilidad fonológica y el desarrollo temprano de la lectoescritura en una muestra longitudinal de 115 niños de Jardín. Los análisis de regresión múltiple y correlacionales indicaron que cada una de las conceptualizaciones del HLE se relacionó consistentemente con los efectos estudiados. Sin embargo, la magnitud de las relaciones varió considerablemente según los efectos, así como también cuando se tuvieron en cuenta otros predictores evolutivos. Estos resultados indican que los estudios futuros sobre el HLE y su papel en el desarrollo de las habilidades de lenguaje y lectoescritura deben tomar en consideración la forma en la que se conceptualiza el contexto del hogar. /// German Die häusliche Schreib- und Leseumgebung (HLE = Home Literacy Environment) ist ein wichtiger Faktor bei der Gestaltung einer Anzahl entwicklungsbedingter und erzieherischer Folgeergebnisse; dennoch bleiben viele Fragen in Bezug auf ihre Konzeptualisierung und Relationen zu verschiedenen Auswirkungen unbeantwortet. Diese Studie untersucht die Relationen von sechs verschiedenen Konzeptualisierungen der HLE zur gesprochenen Sprache, phonologischen Sensitivität und früher Schreib- und Leseentwicklungen in einem Langzeitbeispiel mit 115 Vorschülern. Mehrfachregression und Korrelationsanalysen zeigten, dass jede der HLE Konzeptualisierungen mit den untersuchten Ergebnissen übereinstimmte. Jedoch variierte das Ausmaß der Beziehungen beträchtlich quer durch die Ergebnisse und sobald andere Entwicklungseinflüsse in Rechnung gezogen wurden. Diese Ergebnisse zeigen, daß zukünftige Untersuchungen der HLE und deren Rolle in der Entwicklung von Sprache und Schreib- bzw. Lesefertigkeiten die Umstände in Rechnung ziehen müssen, in der die häusliche Umgebung konzeptualisiert ist. /// French L'environnement écrit familial (EEF) est une variable importante du developpement de nombreux aspects du développement et de l'éducation; toutefois, nombre de questions concernant sa conceptualisation et ses relations avec différents aspects demeurent sans réponses. Cette étude a porté sur les relations de six conceptualisations différentes de l'EEF sur le langage oral, la sensibilité phonologique, et les premiers développements de la littératie à l'aide d'un échantillon de 115 enfants d'âge préscolaire suivis longitudinalement. Des analyses de régression multiple et des corrélations ont montré que chacune des conceptualisations de l'EEF est fortement liée aux aspects étudiés. Cependant, l'ampleur de ces relations varie considérablement d'un aspect à l'autre et quand d'autres prédicteurs du développement sont pris en considération. Ces résultats montrent que les études ultérieures de l'EEF et de son rôle sur le développement des compétences en matière de langage et de littératie devront prendre en considération la façon dont on conceptualise l'environnement familial. /// Cyrillic Влияние дома и отношения членов семьи к печатному слову (HЛE) -- важная переменunknown определяющая целый ряд параметров в развитии и обучении; однако, множество вопр связанных с содержанием HЛE и влиянием HЛE на эти параметры, остаются без ответ рамках продолжительного исследования рассматривались взаимоотношения шести различных составляющих HЛE с устной речью, фонологическим восприятием и ранни развитием грамотности у 115 дошкольников. Многокомпонентный регрессивный и коррелятивный анализ показал, что каждая из составляющих HЛE последовательно св изучаемыми результатами. Однако количественно эта связь в каждом случае различае изменяются показатели и в том случае, когда принимаются во внимание и другие индunknown развития. Эти результаты показывают, что будущие исследования HЛE и его роли в ра языковых навыков и грамотности должны учитывать то, что собственно понимается unknown (т.е. влиянием семьи и отношения домашних к печатному слову).
A concurrent-task methodology was used to investigate relations between the availability of aspects of working memory resources and both strategy selection and execution while simple addition ...equations (e.g., 4 + 3 = 8) were being verified. Consistent with prior research in which production trials have been used, undergraduates selected a variety of procedures other than retrieval. Availability of working memory resources did not generally affect strategy selection. Disrupting central executive and phonological aspects of memory affected strategy execution, but only when min counting was used to solve the problems. These and other features of the results suggest that availability of working memory resources does not contribute to individual differences in strategy selection and time to execute retrieval processes.
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