Problem solving and computational skill: Are they shared or distinct aspects of mathematical cognition?

The purpose of this study was to explore patterns of difficulty in 2 domains of mathematical cognition: computation and problem solving. Third graders (n = 924; 47.3% male) were representatively sampled from 89 classrooms; assessed on computation and problem solving; classified as having difficulty with computation, problem solving, both domains, or neither domain; and measured on 9 cognitive dimensions. Difficulty occurred across domains with the same prevalence as difficulty with a single domain; specific difficulty was distributed similarly across domains. Multivariate profile analysis on cognitive dimensions and chi-square tests on demographics showed that specific computational difficulty was associated with strength in language and weaknesses in attentive behavior and processing speed; problem-solving difficulty was associated with deficient language as well as race and poverty. Implications for understanding mathematics competence and for the identification and treatment of mathematics difficulties are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preliminary development of an interaction matrix for observation of client–therapist relationships in play therapy.

Describes the development of the Carmichael Therapist/Client Interaction Matrix (CTCIM) and presents preliminary findings on its use in supervision of therapists and for empirical study of therapist/client interactions. The purpose of the CTCIM is to graphically depict the relationship between the level of therapist's responses and the client's behaviors in therapy. The CTCIM was used to evaluate 32 sessions in a university play therapy laboratory. Five children (aged 6–10 yrs) were paired with 5 therapists. The 5 children represented a wide range of problems from physical abuse survivors to school adjustment difficulties. The 5 graduate student therapists varied from beginning to moderate counseling experience. A positive correlation was found between therapist's responses and client behavioral outcomes in the preliminary study. Based on the finding that the CTCIM met 4 of the 6 dimensions recommended by P. Howe and L. Silvern (1981) in investigating issues important to therapists and clients, it is concluded that the CTCIM demonstrates potential for empirical studies and for supervision of therapists. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effect of Therapist Availability on the Frequency of Patient-Initiated Between-Session Contact.

Does therapist availability affect the frequency of patient-initiated between-session phone contacts? There are few empirical data to inform therapists on this question: This study was designed to redress this literature gap. Results demonstrated that in general, therapists' availability policies did not strongly relate to patient-initiated contacts. However, there were some exceptions: The more willing therapists were to receive crisis intervention and mental status update calls, the fewer calls they received. Additionally, when therapists were less willing to be contacted between sessions, patients with personality disorders and/or poor global functioning tended to make more nonemergency calls to the therapist, whereas patients with elevated suicidality tended to make fewer nonemergency calls between sessions. The implications of the results on therapists' policies and patients' expectations are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Direct Reduction of Mixtures of Manganese Ore and Iron Ore

This paper presents recent results of direct reduction investigation of different combination of blends of manganese ore, iron ore and coal at the Department of Ferrous Metallurgy (IEHK) of RWTH Aachen University. A mixture of iron and manganese ore in a ratio of 75/25 is a good raw material for steelmaking of high Mn‐alloyed grades. The experimental studies consisting of reduction of (a) fine material and (b) agglomerated material (briquettes) were carried out in the range of 1273 to 1673 K. The behaviour of combined reduction of manganese ore and iron ore and the employment in the direct reduction on a coal and gas basis for production of steels with high Mn content were investigated. It was found that a high metallization degree for Mn can be reached at 1273 K with the reduction of manganese ore by hydrogen‐containing gas. Addition of carbon monoxide to the reducing gas retarded the reduction process. The addition of coal to manganese ore and iron ore blends increased the degree of reduction. The results of carbothermic reduction of briquettes consisting of a mixture of manganese ore and iron ore combined with coal as reducing agent show that a high temperature, a low Mn/Fe ratio and a high Fe₂O₃ content have a favourable effect on the degree of reduction. In order to obtain a high degree of metallization, the temperature should be higher than 1473 K. The reduction of briquettes at higher temperatures (up 1573 K) has shown a molten phase and the separation of slag and metal.     

Molecular Recognition of Two 2,4‐syn‐Functionalized (S)‐Glutamate Analogues by the Kainate Receptor GluK3 Ligand Binding Domain

The kainate receptors are the least studied subfamily of ionotropic glutamate receptors. These receptors are thought to have a neuromodulatory role and have been associated with a variety of disorders in the central nervous system. This makes kainate receptors interesting potential drug targets. Today, structures of the ligand binding domain (LBD) of the kainate receptor GluK3 are only known in complex with the endogenous agonist glutamate, the natural product kainate, and two synthetic agonists. Herein we report structures of GluK3 LBD in complex with two 2,4‐syn‐functionalized (S)‐glutamate analogues to investigate their structural potential as chemical scaffolds. Similar binding affinities at GluK3 were determined for the 2‐(methylcarbamoyl)ethyl analogue (K_i=4.0 μM ) and the 2‐(methoxycarbonyl)ethyl analogue (K_i=1.7 μM ), in agreement with the similar positioning of the compounds within the binding pocket. As the binding affinity is similar to that of glutamate, this type of Cγ substituent could be used as a scaffold for introduction of even larger substituents reaching into unexplored binding site regions to achieve subtype selectivity.     

Surface, kinetics and electrocatalytic properties of the Ti/(Ti + Ru + Ce)O2-system for the oxygen evolution reaction in alkaline medium

Ti-supported (Ti + Ru + Ce)O₂ electrodes, prepared at 450 °C, were characterised by XRD, open-circuit potential (E_oc), capacity data (C) and morphology factor (φ) determinations. XRD measurements showed mixed oxides present a low degree of crystallinity. E_oc-data and CV-spectra support surface electrochemistry of mixed oxides is governed by the Ru(III)/Ru(IV) redox couple. In situ surface characterisation revealed the active surface area increases on increasing nominal CeO₂-content. φ-Values remained in the 0.18-0.3 interval supporting the coatings have a low electrochemical porosity. Kinetics was studied recording polarisation and chronopotentiometric curves, which permitted to determine the Tafel slope and reaction order (with respect to OH⁻), in the low and high overpotential domains. Tafel slope data, b, presented a dependence on overpotential and oxide composition indicating the OER electrode mechanism depends on these variables. A unit reaction order with respect to OH⁻ was found for all electrode compositions investigated. The theoretical analysis of the electrode mechanism permitted to analyse the changes in the experimental Tafel slopes taking into account modifications in the apparent electronic transfer coefficient, α_ap. Analysis of the true and apparent electrocatalytic activities revealed the O₂-evolution reaction rate is affected by oxide composition due to morphologic effects.     

Ethanolysis of Refined Soybean Oil Assisted by Sodium and Potassium Hydroxides

The ethanolysis of refined soybean oil was investigated through a 2³ experimental design that was carried out under the following levels: ethanol:oil molar ratios (MR) of 6:1 and 12:1, NaOH concentrations of 0.3 and 1.0 wt% in relation to the oil mass, and reaction temperatures of 30 and 70 °C. The ethanol:oil MR and the alkali concentration had an almost equivalent influence on the reaction yield, whereas the influence of increased reaction temperatures was very limited and higher catalyst concentrations led to greater yield losses due to the formation of soap. Ethyl ester yields of 97.2% were obtained at 70 °C, MR of 12:1 and 0.3 wt% NaOH. Replacement of 0.3 wt% NaOH by 1.0 wt% KOH under the same reaction conditions led to lower ester yields. Likewise the former, KOH provided the maximum ester yield (95.6%) at the highest molar ratio (12:1), with the reaction temperature having little influence on the catalyst performance. Ester yields beyond 98% were only achieved when a second ethanolysis stage was included in the process. In this regard, the application of 2 wt% Magnesol^® after the first ethanolysis stage eliminated the need for water washing prior to the second ethanolysis stage and helped to generate a final product with less contaminating unreacted glycerides.     

Synchrotron radiation X‐ray micro‐fluorescence: Protocol to study mesenchymal stem cells

The micro‐X‐ray fluorescence by synchrotron radiation (μ‐XRF) is a method to determine the composition of tissues without destroying the samples. However, this technique has never been used for the analysis of mesenchymal stem cells (MSC). This study compared different protocols for fixing, storing, preserving, and establishing the correct numbers of dental derived MSC submitted to μ‐XRF analysis. Stem cells were obtained from human dental tissue. After cell expansion, and MACS isolation, the samples were fixed and the following quantities of cells 1 × 10⁴ to 1 × 10⁷ were divided in two groups: G1: fixed in 4% paraformaldehyde diluted in phosphate‐buffered saline solution, and G2: fixed in 4% paraformaldehyde diluted in MilliQ water. The G1 cells showed precipitation of chemical components from the solution resulting in the formation of salt crystals while G2 cells were clear and almost transparent in the sample holder. With regards to cells concentration, the best results occurred when four droplets of 1 × 10⁷ cells were analyzed. This work shows that to identify and study the distribution of trace elements in MSC by μ‐XRF, the best protocol is fixation in 4% paraformaldehyde diluted with MilliQ water at 4°C and a concentration of four incremental droplets of 1 × 10⁷ cells. Microsc. Res. Tech. 79:149–154, 2016. © 2016 Wiley Periodicals, Inc.     

Effect of interface on elastic and toughening behavior in poly lactic acid/thermoplastic starch blends: Micromechanical finite element analysis

It is frequently emphasized that the action of interfacial adhesion is a critical parameter to improve the stiffness and toughness of polylactic acid/thermoplastic starch (PLA/TS) blends. In this work, the micromechanical behavior of PLA/TS blends with droplet morphology selected from literature is predicted and analyzed systematically by finite element analysis. A quantitative assessment of the effect of interface (perfect or imperfect) on the elastic behavior and craze initiation for toughening of PLA/TS blends is presented. For the elastic behavior, the PLA phase is the blend's load-bearing component as the TS is more compliant than PLA, so an interface perfectly bonded reduces the blend's elastic modulus when compared to the modulus obtained if the interface is weakly bonded. Regarding the toughening behavior, as a compliant phase, the TS has the potential to nucleate stable crazes in the host PLA matrix independently of the degree of interfacial adhesion because the highly stressed region lies near the equator of the particle; nonetheless, the critical stress for craze initiation is very sensitive to the TS particle size. On the other hand, as the TS is less capable than PLA to develop large hydrostatic stresses, the TS has a low potential to dissipate energy by cavitation.     

Comparison of the Patient Health Questionnaire and the Older Adult Health and Mood Questionnaire for self-reported depressive symptoms after spinal cord injury.

Objective: To directly compare estimates of potential depressive disorders and clinically significant depressive symptoms using the Patient Health Questionnaire-9 (PHQ-9) and Older Adult Health and Mood Questionnaire (OAHMQ) among participants with spinal cord injury (SCI). Research Design: 727 participants from a hospital in the Southeastern United States were administered the PHQ-9 and OAHMQ during a follow-up survey. We compared the rates of depressive disorders using cutoff scores and diagnostic criteria for each instrument. No independent psychiatric diagnostic interviews were conducted. Results: The PHQ-9 and OAHMQ were significantly correlated (r = .78), and both were correlated with satisfaction with life (r = ?.48, ?.54). Using recommended diagnostic scoring procedures, 10.7% of participants met the diagnostic criteria for major depressive disorder with the PHQ-9; 9.3% met the criteria for major depression based on PHQ-9 ≥ 10; and 19.7% based on PHQ-9 ≥ 15. Using the OAHMQ, 19.7% reported probable major depression and 44.5% clinically significant symptomatology. Conclusions: The measures were highly correlated overall. However, the estimated prevalence of depressive disorders varied substantially between the 2 instruments. These estimates were comparable to those previously reported for each instrument (i.e., higher rates with the OAHMQ). Therefore, differing estimates of depressive disorders reported in the literature using these instruments were largely attributable to the instruments themselves. (PsycINFO Database Record (c) 2010 APA, all rights reserved)