Planning in human children (Homo sapiens) assessed by maze problems on the touch screen.

The authors examined how human children perform on maze tasks on the touch screen and whether the children plan the solution of the mazes. In Experiment 1, the authors exposed children around 3 years of age to a maze having an L-shaped line as a barrier that can be solved by moving an illustration of a dog (the target) to that of a bone (the goal) with their fingers. The participants successfully solved the maze by taking efficient routes more frequently than chance, although the authors found no evidence that a preview of the maze before starting to solve the task facilitated their performance. In Experiment 2, using a plus-shaped maze, the authors found that 3- and 4-year-old children plan and adjust their moves while solving the maze, with 4-year-olds showing more advanced and higher-level planning than 3-year-olds. Similarity of these results to what the authors previously found in pigeons tested in the same tasks may suggest an analogy for planning capacity in the behavioral level across taxa and developmental stages. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conformational changes in the A1 domain of von Willebrand factor modulating the interaction with platelet glycoprotein Ibalpha

The interaction between von Willebrand factor (vWF) A1 domain and platelet glycoprotein Ib alpha occurs in the presence of high shear stress or when vWF becomes immobilized onto a surface but not appreciably in the normal circulation. To investigate the structural properties regulating A1 domain function, we have used recombinant fragments prepared either in cyclic form with oxidized Cys509-Cys695 disulfide bond or reduced and alkylated. Interaction with glycoprotein Ibalpha was assessed by testing inhibition of monoclonal antibody LJ-Ib1 binding to platelets and inhibition of shear-induced platelet aggregation mediated by native vWF. Fragments exposed to pH between 2.5 and 3.5 adopted the molten globule conformation with loosened tertiary structure intermediate between native and completely unordered state. Maximal receptor binding activity was observed when fragments kept at acidic pH, particularly after reduction of the Cys509-Cys695 disulfide bond, were subjected to quick refolding by rapid pH increase. In contrast, slow refolding by incremental pH change over several hours resulted in at least 20-fold lower activity. A specific single point mutation (I546V) resulted in enhanced receptor binding, whereas another mutation (S561G) caused markedly reduced binding. These results provide experimental evidence that conformational transitions can modulate function of the vWF A1 domain in solution.     

Therapeutic response and potential pitfalls in phase I clinical trials of anticancer agents conducted in Japan

A case of hepatic amebic abscess is presented that was treated successfully by laparoscopy. The patient was fully worked up, including computed tomography (CT) scan, video-colonoscopy, and blood profiles. The laparoscopic surgical technique is fully discussed and proved to be a very useful tool in the management of this problem, obviating the need for a formal laparotomy and its potential complications.     

Formation of giant liposomes promoted by divalent cations: critical role of electrostatic repulsion

Spontaneous formation of giant unilamellar liposomes in a gentle hydration process, as well as the adhesion energy between liposomal membranes, has been found to be dependent on the concentration of divalent alkali cations, Ca2+ or Mg2+, in the medium. With electrically neutral phosphatidylcholine (PC), Ca2+ or Mg2+ at 1-30 mM greatly promoted liposome formation compared to low yields in nonelectrolyte or potassium chloride solutions. When negatively charged phosphatidylglycerol (PG) was mixed at 10%, the yield was high in nonelectrolytes but liposomes did not form at 3-10 mM CaCl2. In the adhesion test with micropipette manipulation, liposomal membranes adhered to each other only in a certain range of CaCl2 concentrations, which agreed with the range where liposome did not form. The adhesion range shifted to higher Ca2+ concentrations as the amount of PG was increased. These results indicate that the divalent cations bind to and add positive charges to the lipids, and that membranes are separated and stabilized in the form of unilamellar liposomes when net charges on the membranes produce large enough electrostatic repulsion. Under the assumption that the maximum of adhesion energy within an adhesive range corresponds to exact charge neutralization by added Ca2+, association constants of PC and PG for Ca2+ were estimated at 7.3 M(-1) and 86 M(-1), respectively, in good agreement with literature values.     

Slip casting of sialon for pressureless sintering

The properties of aqueous slips of sialon were studied. Ammonium polyacrylate was used as a deflocculant. It was shown that the apparent viscosity for slips with solid content 40 vol % was low and the slip resulting from this is almost Newtonian. This slip proved sufficiently fluid for casting. However, the apparent viscosity for slips with solid content 45 vol % increased significantly. The slips resulting from this exhibited dilatant flow and were difficult to cast. The viscosity, fluidity, and pH of the slips were studied and tiles were cast and fired in nitrogen at 1740 °C for 3 h to a bulk density of 3.20 g cm^–3.     

Gastric syphilis: polymerase chain reaction detection of treponemal DNA in pseudolymphomatous lesions

Syphilis is an unexpected diagnosis in the stomach. To establish the diagnosis, evidence of Treponema pallidum in the gastric lesion is necessary. However, it is sometimes difficult to prove the presence of the organisms by conventional methods. The authors describe two cases of early gastric syphilis with pseudolymphomatous histology in which T pallidum gene was detected by the polymerase chain reaction (PCR) using paraffin biopsy sections. The gastric lesion of each case endoscopically and histologically simulated that of malignant lymphoma. However, no clonality was proved by immunohistochemistry or PCR gene rearrangement analysis. No spirochetal organisms were detected with certainty by Warthin-Starry silver stain, whereas the organisms were shown by immunofluorescent stain in one patient. A PCR study showed the treponemal DNA in both patients, and its validity was supported by a direct sequencing and a restriction enzyme digestion. Positive results of serological tests for syphilis and regression of the lesions after antisyphilitic treatment were confirmatory of the diagnosis. Gastric syphilis should be considered as a differential diagnosis when an atypical lymphoid infiltrate fails to show monoclonality. The present PCR method would be helpful in showing T pallidum using routinely processed small biopsy specimens as the tissue source.     

Some factors for the space charge formation in polyethylene

Information on space-charge behavior in thick insulated samples aids in understanding the dc characteristics of polymer-insulated dc cables. The pulsed electroacoustic method is used to investigate several space charge formation factors in 2 mm-thick polyethylene (PE). The following results were obtained. For measurement factors: (1) A polymeric semiconducting electrode provides a more accurate measurement than does a metal electrode as a result of better matching of acoustic impedance with PE. (2) Within a dc electrical stress range of several tens kV/mm, the space charge distributions under and after dc voltage application are almost the same; this is due to a comparatively long time of space-charge decay. (3) The space-charge distribution of a plate sample agrees with that of a cable sample having the same insulation thickness. For insulating material factors: (1) The amount of space charge in crosslinked polyethylene (XLPE) is much larger than that in low-density PE (base of XLPE). The space charge of XLPE continues to increase even after dc voltage application (24 h); that of LDPE reaches equilibrium with a few hours. (2) The aforementioned space charge difference between XLPE and LDPE is assumed to be caused by ionic impurities in XLPE, not by the additives themselves (acetophenon and cumylalcohol as byproducts of cross linking and antioxidant).     

Oxidation properties of Zr-Nb alloys at 500-600 °C under low oxygen potentials

Zr-Nb alloys with 1-10 wt.% Nb content were oxidized at 500-600 °C in the CO-CO₂ gas mixtures. The oxidation weight gain increased with Nb content and the kinetics except for Zr-1Nb alloy changed from cubic rate to linear one at 600 °C for a long period of time, 7 d. The cubic rate constant was almost insensitive to oxygen potential of oxidizing atmosphere. As the oxidation resistance deteriorated, the volume ratio of tetragonal to monoclinic zirconia phase and the relevant compressive stress in oxide film decreased with increase of Nb content. Before and after oxidation, Nb re-distribution could not be observed under the present experimental condition.