Intraindividual variability in inhibitory function in adults with ADHD - an ex-Gaussian approach

OBJECTIVE: Attention deficit disorder (ADHD) is commonly associated with inhibitory dysfunction contributing to typical behavioral symptoms like impulsivity or hyperactivity. However, some studies analyzing intraindividual variability (IIV) of reaction times in children with ADHD (cADHD) question a predominance of inhibitory deficits. IIV is a measure of the stability of information processing and provides evidence that longer reaction times (RT) in inhibitory tasks in cADHD are due to only a few prolonged responses which may indicate deficits in sustained attention rather than inhibitory dysfunction. We wanted to find out, whether a slowing in inhibitory functioning in adults with ADHD (aADHD) is due to isolated slow responses. METHODS: Computing classical RT measures (mean RT, SD), ex-Gaussian parameters of IIV (which allow a better separation of reaction time (mu), variability (sigma) and abnormally slow responses (tau) than classical measures) as well as errors of omission and commission, we examined response inhibition in a well-established GoNogo task in a sample of aADHD subjects without medication and healthy controls matched for age, gender and education. RESULTS: We did not find higher numbers of commission errors in aADHD, while the number of omissions was significantly increased compared with controls. In contrast to increased mean RT, the distributional parameter mu did not document a significant slowing in aADHD. However, subjects with aADHD were characterized by increased IIV throughout the entire RT distribution as indicated by the parameters sigma and tau as well as the SD of reaction time. Moreover, we found a significant correlation between tau and the number of omission errors. CONCLUSIONS: Our findings question a primacy of inhibitory deficits in aADHD and provide evidence for attentional dysfunction. The present findings may have theoretical implications for etiological models of ADHD as well as more practical implications for neuropsychological testing in aADHD

Graphene -- Based Nanocomposites as Highly Efficient Thermal Interface Materials

We found that an optimized mixture of graphene and multilayer graphene - produced by the high-yield inexpensive liquid-phase-exfoliation technique - can lead to an extremely strong enhancement of the cross-plane thermal conductivity K of the composite. The "laser flash" measurements revealed a record-high enhancement of K by 2300 % in the graphene-based polymer at the filler loading fraction f =10 vol. %. It was determined that a relatively high concentration of single-layer and bilayer graphene flakes (~10-15%) present simultaneously with thicker multilayers of large lateral size (~ 1 micrometer) were essential for the observed unusual K enhancement. The thermal conductivity of a commercial thermal grease was increased from an initial value of ~5.8 W/mK to K=14 W/mK at the small loading f=2%, which preserved all mechanical properties of the hybrid. Our modeling results suggest that graphene - multilayer graphene nanocomposite used as the thermal interface material outperforms those with carbon nanotubes or metal nanoparticles owing to graphene's aspect ratio and lower Kapitza resistance at the graphene - matrix interface.Comment: 4 figure

Granulocyte Transfusions in Leukopenic Dogs: In Vivo and In Vitro Function of Granulocytes Obtained by Continuous-Flow Filtration Leukopheresis

Abstract The present studies were carried out to (1) evaluate a leukoadhesive technique for obtaining granulocytes for transfusion, (2) assess the granulocytes by in vitro techniques, and (3) determine the efficacy of granulocyte transfusion in preventing sepsis in leukopenic dogs. Dogs were rendered transiently leukopenic (&lt; 500 per cu mm) by intravenous cyclophosphamide, 40 mg/kg. Quantitative and qualitative blood cultures were obtained from all animals until death or hematologic recovery. Granulocytes were obtained on nylon filters by a continuous flow system and eluted with an ACD plasma saline solution. Granulocyte function was studied in vitro by chemotaxis, phagocytosis, intracellular killing, and electron microscopy. In vivo studies consisted of the measurement of granulocyte increments in transfused leukopenic dogs, T ½ of infused granulocytes, and protection of transfused dogs from septicemic episodes. Eluted granulocytes, when compared to normal controls, showed reduction in in vitro functions. These functions improved in granulocytes isolated post-transfusion from recipient dogs. An average of 3 x 1010 granulocytes could be obtained during a 1-hr leukopheresis of normal donors. Increments in recipient dogs averaged 2590 per cu mm. Five nontransfused leukopenic dogs developed septicemia and died within 7 days. Six dogs were treated with infusions of granulocytes. Three recovered completely, and three died of thrombocytopenic hemorrhage with negative blood cultures. One dog showed a transiently positive blood culture that became negative following transfusion. Septic episodes were significantly reduced in granulocyte transfused dogs (p &lt; 0.01). It was concluded that continuous-flow leukofiltration yielded granulocytes in sufficient number and with adequate functional capabilities to provide significant protection against septic death in the leukopenic host.</jats:p

Distribution of subjects with regard to age, gender and education.

<p><b>NOTE:</b>^* Education was ordinally measured with 1 =  Compulsory schooling not completed (less than 9 years of school) or special school; 2 =  Completed compulsory schooling (9–10 years of school); 3 =  Completed vocational training (10–12 years of school); 4 =  Highschool graduation with university entrance exam (12–13 years of school); 5 =  University or college degree.</p><p>Distribution of subjects with regard to age, gender and education.</p

Experimental study on the porous structure and compressibility of tectonized coals

This paper presents experimental investigations on the porous structure and compressibility of six representative tectonized coals, which were geologically formed because of post-formation tectonic deformation of the coal seam, resulting in various brittle and plastic structure development in the seam, such as fissure and fold. The investigations were carried out using microscopy and mercury intrusion porosimetry, providing experimental information about better characterization of the coal structure for coalbed methane recovery from tectonized coal seams. In combination with measurements of vitrinite reflectance and pore size distribution, the mercury intrusion porosimetry data were further analyzed with the fractal theory and used to determine the pore compressibility of the coal samples. The results show that tectonic deformation mainly reformed the bigger pores (pore size above 100 nm). In general, the increased tectonic deformation led to more open pores and, hence, the enhanced connectivity of the pore network. In fractal analysis, a linear relation was used to fit the mercury intrusion data at high pressure instead of the power law that was typically used in previous studies on ordinary coals. The volume-pressure curves obtained by mercury intrusion measurements for all coal samples exhibit a strong dependence relation with the deformation extent. The pore compressibility of these coals obviously decreases as the deformation extent increased, with only one exception for all coal samples studied. This implies that the weak deformation may be corresponding to a high compressibility. Moreover, the results also show that the rank may be responsible for a significant part of the differences in porosity and pore compressibility as well