The influence of learner-generated domain representations on learning combinatorics and probability theory

The aim of the current study was to examine the effects of providing support in the form of tools for constructing representations, and in particular the differential effects of the representational format of these tools (conceptual, arithmetical, or textual) in terms of perceived affordances and learning outcomes. The domain involved was combinatorics and probability theory. A between-subjects pre-test–post-test design was applied with secondary education students randomly distributed over four conditions. Participants completed the same tasks in a simulation-based learning environment. Participants in three experimental conditions were provided with a representational tool that could be used to construct a domain representation. The experimental manipulation concerned the format of the tool (conceptual, arithmetical, or textual). Participants in a control condition did not have access to a representational tool. Data from 127 students were analyzed. It was found that the construction of a domain representation significantly improved learning outcomes. The format in which students constructed a representation did not directly affect learning outcomes or the quality of the created domain representations. The arithmetical format, however, was the least stimulating for students to engage in externalizing their knowledge.     

Construct validity of an attention rating scale for traumatic brain injury.

Attention deficits are nearly ubiquitous after traumatic brain injury (TBI). In the subacute phase of moderate to severe TBI, these deficits may be difficult to measure with the precision needed to predict outcomes, assess degree of recovery, and monitor treatment response. This article reports the findings of four studies, three observational and one a randomized, controlled treatment trial of methylphenidate (MP), designed to provide construct validation of the Moss Attention Rating Scale (MARS), an observational measure of attention dysfunction following TBI. One hundred seven participants with moderate to severe TBI were enrolled during treatment on an inpatient rehabilitation unit. MARS scores were provided independently by four rehabilitation disciplines (Physical, Occupational and Speech Therapies and Nursing). Results indicated that the MARS: (1) is more strongly related to concurrent measures of cognitive versus physical disability, supporting its validity as a measure of cognition, (2) is more strongly related to concurrent psychometric measures of attention versus measures thought to rely less on attention, supporting its validity as a measure of attention; and (3) predicts 1-year outcomes of TBI better than psychometric measures of attention. However, the MARS (4) was not differentially affected by MP versus placebo treatment. Results support the construct validity and utility of the MARS, with further research needed to clarify its role in treatment outcome assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Expressed protein ligation for a large dimeric protein

Expressed protein ligation (EPL) is a protein engineering tool for post-translational ligation of protein or peptide fragments. This technique allows modification of specific parts of proteins, opening possibilities for incorporating probes for biophysical applications such as nuclear magnetic resonance (NMR) or fluorescence spectroscopy. The application for oligomeric proteins, however, is restricted by the need to obtain a large excess of active dimer over reactants and intermediates. Here, we explored the suitability of the EPL reaction for large dimeric proteins using the molecular chaperone Hsp90 as a model. We systematically varied the reaction conditions and the preparation protocols for the reactants. Modulation of the ligation site by shortening the flexible segment at the N-terminus of the C-terminal reactant increased the yield sufficiently to isolate the product by chromatography. Under those conditions, 41% of the used C-terminal fragment could be successfully ligated. We discuss possible up-scaling for segmental isotope labelling for NMR applications.     

Bioorthogonally Applicable Fluorescence Deactivation Strategy for Receptor Kinetics Study and Theranostic Pretargeting Approaches

The availability of a receptor for theranostic pretargeting approaches was assessed by use of a new click‐chemistry‐based deactivatable fluorescence‐quenching concept. The efficacy was evaluated in a cell‐based model system featuring both membranous (available) and internalized (unavailable) receptor fractions of the clinically relevant receptor chemokine receptor 4 (CXCR4). Proof of concept was achieved with a deactivatable tracer consisting of a CXCR4‐specific peptide functionalized with a Cy5 dye bearing a chemoselective azide handle (N₃‐Cy5‐AcTZ14011). Treatment with a Cy7 quencher dye (Cy7‐DBCO) resulted in optically silent Cy7‐[click]‐Cy5‐AcTZ14011. In situ, a >90 % FRET‐based reduction of the signal intensity of N₃‐Cy5‐AcTZ14011 [K_D=(222.4±25.2) nm ] was seen within minutes after quencher addition. In cells, discrimination between the membranous and the internalized receptor fraction could be achieved through quantitative assessment of quenching/internalization kinetics. Similar evaluation of an activatable tracer variant based on the same targeting moiety (Cy5‐S‐S‐Cy3‐AcTZ14011) was unsuccessful in vitro. As such, using the described deactivatable approach to screen membrane receptors and their applicability in receptor‐(pre‐)targeted theranostics can become straightforward.     

Adenylate Kinase 4—A Key Regulator of Proliferation and Metabolic Shift in Human Pulmonary Arterial Smooth Muscle Cells via Akt and HIF-1α Signaling Pathways

Increased proliferation of pulmonary arterial smooth muscle cells (PASMCs) in response to chronic hypoxia contributes to pulmonary vascular remodeling in pulmonary hypertension (PH). PH shares numerous similarities with cancer, including a metabolic shift towards glycolysis. In lung cancer, adenylate kinase 4 (AK4) promotes metabolic reprogramming and metastasis. Against this background, we show that AK4 regulates cell proliferation and energy metabolism of primary human PASMCs. We demonstrate that chronic hypoxia upregulates AK4 in PASMCs in a hypoxia-inducible factor-1α (HIF-1α)-dependent manner. RNA interference of AK4 decreases the viability and proliferation of PASMCs under both normoxia and chronic hypoxia. AK4 silencing in PASMCs augments mitochondrial respiration and reduces glycolytic metabolism. The observed effects are associated with reduced levels of phosphorylated protein kinase B (Akt) as well as HIF-1α, indicating the existence of an AK4-HIF-1α feedforward loop in hypoxic PASMCs. Finally, we show that AK4 levels are elevated in pulmonary vessels from patients with idiopathic pulmonary arterial hypertension (IPAH), and AK4 silencing decreases glycolytic metabolism of IPAH-PASMCs. We conclude that AK4 is a new metabolic regulator in PASMCs interacting with HIF-1α and Akt signaling pathways to drive the pro-proliferative and glycolytic phenotype of PH.     

Two-dimensional electronic spectroscopy reveals the dynamics of phonon-mediated excitation pathways in semiconducting single-walled carbon nanotubes

Electronic two-dimensional Fourier transform (2D-FT) spectroscopy is applied to semiconducting single-walled carbon nanotubes and provides a spectral and time-domain map of exciton-phonon assisted excitations. Using 12 fs long pulses, we resolve side-bands above the E(22) transition that correspond with the RBM, G, G', 2G and other multiphonon modes. The appearance of 2D-FT spectral cross-peaks explicitly resolves discrete phonon assisted population transfer that scatters excitations to the E(22) (Γ-pt) state, often through a second-order exciton-phonon coupling process. All 2D-FT peaks exhibit a strong peak amplitude modulation at the G-band period (21 fs) which we show originates from an impulsive stimulated Raman process that populates a ground-state G-band vibrational coherence over a 1.3 ps phonon lifetime.     

Modeling of a compact functionally graded cellular structure: a finite element study for medium and high strain rates

The work discussed here is a continuation of study performed previously (Ali et al. in Int J Adv Eng Softw 39:95–106, 2008), in which we presented a detailed analysis of quasi-static and low dynamic response (up to strain rates of 1,200 s^?1) for a compact functionally graded cellular structure found in a banana peel. In this paper, we focus on the in-plane response of the graded structure under medium and high velocity impacts (strain rates ranging from 2,400 to 12,416 s^?1). A theoretical model developed earlier (Ali et al. in Int J Adv Eng Softw 39:95–106, 2008) for predicting the static, quasi-static, and low dynamic response of the graded structure is modified to take into account high dynamic effects. Different critical energy absorbing characteristics, e.g., deformation modes, collapsing mechanism, crushing stress, locking strain, total energy absorbed, etc. are discussed. The output of the high strain analytical model is compared with finite element simulations. The results show that the analytical model aligns well with finite element output for high dynamic cases.     

Are changes in blood pressure and total cholesterol related to changes in mood? An 18-month study of men and women.

The authors investigated the within-person association of reported mood with blood pressure and total cholesterol (TC) levels, each assessed 4 times over an 18-month period in 128 men and 154 women. Change over time in tense arousal was significantly positively associated with changes over time in systolic blood pressure (SBP) and diastolic blood pressure (DBP) but not TC. A change in hedonic tone was significantly associated with SBP (an increase in negative affect was associated with an increase in SBP) but not with DBP or TC. There were no sex differences in associations of mood with SBP or TC. However, increases in tense arousal and negative affect were significantly associated with an increase in DBP for women but not men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)