A low-cost Mr compatible ergometer to assess post-exercise phosphocreatine recovery kinetics

Objective

To develop a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems to reliably quantify metabolic parameters in human lower leg muscle using phosphorus magnetic resonance spectroscopy.

Materials and methods

We constructed an MR compatible ergometer using commercially available materials and elastic bands that provide resistance to movement. We recruited ten healthy subjects (eight men and two women, mean age ± standard deviation: 32.8 ± 6.0 years, BMI: 24.1 ± 3.9 kg/m²). All subjects were scanned on a 7 T whole-body magnet. Each subject was scanned on two visits and performed a 90 s plantar flexion exercise at 40% maximum voluntary contraction during each scan. During the first visit, each subject performed the exercise twice in order for us to estimate the intra-exam repeatability, and once during the second visit in order to estimate the inter-exam repeatability of the time constant of phosphocreatine recovery kinetics. We assessed the intra and inter-exam reliability in terms of the within-subject coefficient of variation (CV).

Results

We acquired reliable measurements of PCr recovery kinetics with an intra- and inter-exam CV of 7.9% and 5.7%, respectively.

Conclusion

We constructed a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems, which allowed us to quantify reliably PCr recovery kinetics in lower leg muscle using ³¹P-MRS.

     

Self‐Assembly of Perovskite for Fabrication of Semitransparent Perovskite Solar Cells

This work reports on the preparation of semitransparent perovskite solar cells. The cells transparency is achieved through a unique wet deposition technique that creates perovskite grids with various dimensions. The perovskite grid is deposited on a mesoporous TiO₂ layer, followed by hole transport material deposition and evaporation of a semitransparent gold film. Control of the transparency of the solar cells is achieved by changing the perovskite solution concentration and the mesh openings. The semitransparent cells demonstrate 20–70% transparency with a power conversion efficiency of 5% at 20% transparency. This is the first demonstration of the possibility to create a controlled perovskite pattern using a direct mesh‐assisted assembly deposition method for fabrication of a semitransparent perovskite‐based solar cell.     

Repeated communication and Ramsey graphs

We study the savings afforded by repeated use in two zero-error communication problems. We show that for some random sources, communicating one instance requires arbitrarily many bits, but communicating multiple instances requires roughly 1 bit per instance. We also exhibit sources where the number of bits required for a single instance is comparable to the source's size, but two instances require only a logarithmic number of additional bits. We relate this problem to that of communicating information over a channel. Known results imply that some channels can communicate exponentially more bits in two uses than they can in one use     

Selectins, T-cell rolling and inflammation

The selectins, a family of Ca(2+)-dependent lectins, are expressed on inflamed vascular endothelium and some leukocyte subsets, and mediate adhesive contacts between blood cells and vessel walls. These interactions are loose and reversible, operate under conditions of shear flow, and result in leukocyte rolling along the vessel wall. The structure of the selectins and their ligands makes them uniquely suited for supporting the type of bond formation and dissociation that must prevail in order for a cell to be able to roll under conditions of flow. Because rolling precedes (and appears to be essential for) the integrin-mediated firm arrest before extravasation in response to inflammatory or infectious stimuli, inhibition of selectin function has potential for anti-inflammatory therapy, but also presents some significant challenges because of the complexity of the processes involved.     

Induction of T cell adhesion to extracellular matrix or endothelial cell ligands by soluble or matrix-bound interleukin-7

The putative effects of interleukin (IL)-7, operating in the context of extracellular matrix (ECM), on the adhesion of human T cells were examined. Recombinant human, IL-7 was found to bind ECM or fibronectin (FN) with IC50 values of 10-100 nM. Nanogram amounts of both soluble and, especially, FN- or ECM-bound IL-7, which differentially affected the morphologies of FN-adherent T cells, induced the adhesion of resting CD4+ and CD8+ T cells in dose-dependent and beta 1 integrin-dependent manners. Under static and flow conditions, soluble IL-7 also induced the binding of unstimulated T cells to vascular cell adhesion molecule-1, suggesting that this cytokine can also modulate integrin binding to endothelial cell ligands. The effects of affinity modulation by IL-7 of FN-specific beta 1 integrins depend on the presence of soluble FN, which inhibited T cell adhesion to FN induced by FN-bound IL-7 or by an integrin-specific affinity-modulating monoclonal antibody, but not by soluble IL-7 or phorbol 12-myristate 13-acetate. These findings provide an example of a major ECM integrin ligand, FN, which is capable of modulating its adhesive interactions with specific immune cells by associating with and presenting a cytokine in a bio-active state.     

Mother's insightfulness regarding their infants' internal experience: Relations with maternal sensitivity and infant attachment.

This study examined the associations among mothers' insightfulness into their infants' internal experience, mothers' sensitivity to their infants' signals, and infants' security of attachment to their mothers. The insightfulness of 129 mothers of 12-month-old infants was assessed by showing mothers 3 videotaped segments of observations of their infants and themselves and interviewing them regarding their infants' and their own thoughts and feelings. Interviews were classified into 1 insightful and 3 noninsightful categories. Mothers' sensitivity was assessed during play sessions at home and at the laboratory, and infant-mother attachment was assessed with the Strange Situation. Mothers classified as positively insightful were rated as more sensitive and were more likely to have securely attached children than were mothers not classified as positively insightful. Insightfulness also accounted for variance in attachment beyond the variance explained by maternal sensitivity. These findings add an important dimension to research on caregiving, suggesting that mothers' seeking of explanations for the motives underlying their infants' behavior is related to both maternal sensitivity and infant attachment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reductions in self-injury produced by transcutaneous electrical nerve stimulation

Transcutaneous electrical nerve stimulation is used to reduce pain but also may be useful for self-injurious behavior (SIB). In the current investigation, a microcurrent electromedical device, classified as a transcutaneous electrical nerve stimulator (TENS), was applied with a man with Down syndrome who displayed SIB that persisted in the absence of social contingencies. Although clinically significant results were not maintained, a clear difference in the rates of SIB during active and inactive TENS was observed.     

"The effect of motivation of judgment depends on the difficulty of the judgment": Correction.

Reports an error in the original article by B. W. Pelham and E. Neter (Journal of Personality and Social Psychology, 1995[Apr], Vol 68[4], 581–594). The title of the article reported on page 581 was incorrect; however, the title was correct in the table of contents. (The following abstract of this article originally appeared in record 1995-24088-001.) Three studies tested the hypothesis that high levels of motivation facilitate accurate judgments when judgments are relatively easy but debilitate judgments when judgments are relatively difficult. Each study focused on a different judgmental heuristic, and each made use of different motivation and task difficulty manipulations. In all 3 studies, high levels of motivation increased judgmental accuracy in the case of easy judgments and decreased judgmental accuracy in the case of difficult judgments. Theoretical implications and ecological limitations of these findings are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of activity level in children revisited: Effects of mother presence.

D. K. Routh et al (see record 1974-25047-001) found a consistent decrease in children's activity in a standardized playroom over the ages 3–9 yrs. The present experiment (using 100 10 mo–5 yr olds) was an attempt to extend these findings downward to the age of 10 mo, which necessitated certain changes in procedures. Surprisingly, in Exp I there was a significant increase in activity level over the ages from 3 to 5 yrs. Exp II (96 3-, 4-, and 5-yr-olds) then varied factorially the procedural differences between the 1974 Routh et al study and Exp I, namely the furnishings (tables and chairs vs rugs), type of toys (child toys vs baby toys), and the presence or absence of the child's mother from a small adjoining cubicle. The anomalous findings of the other 2 studies were reproduced and found to be due to the effects of mother presence rather than the other factors varied. With mother present, 5-yr-olds (but not 3- or 4-yr-olds) were significantly more active than with mother absent. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)