Cosmic Ray Production of Rare Gas Radioactivities and Tritium in Lunar Material

The argon radioactivities (37)Ar and (39)Ar were obtained by vacuum melting from interior and exterior portions of rock 10057 and from a portion of the fines from the bulk sample container. The release of argon and tritium as a function of the temperature was followed for the fine material. A comparison is made of the activities observed in the lunar samples with those expected from the spallation of iron, titanium, and calcium. From these data and the (38)Ar content, the cosmic ray exposure age of rock 10057 is deduced as 110 x 10(6) years.

Acetyl disulfide, (CH3COS)2, and bis-(thioacetoy) aurate (I) complex, Au(CH3CHOS)2,-histochemical substrates of unusual properties with acetylcholinesterase

The histochemical reaction for acetylcholinesterase (AChE) employing acetyl disulfide ([CH3COS]2, or AcDiS) as substrate and 0.006 M Pb(NO3)2 as capturing agent was characterized by (1) a sigmoid curve for velocity of hydrolysis versus substrate concentration and (2) a red precipitate (presumably [CH3COSS]2Pb) at sites of AChE at the motor endplates (MEP's) and (from spontaneous hydrolysis) in the supernatant solution. With the addition of 0.03 M thiolacetic acid (TA) to the incubation medium, which by itself produced little or no histochemical staining, the foregoing characteristics were changed to (1) a bell-shaped curve, with the peak at 0.003 M AcDiS, and (2) a black precipitate (presumably PbS) at the MEP's and in the supernatant solution; in addition, the velocity of hydrolysis was increased approximately 100-fold. Comparable differences were obtained with AcDiS as substrate when using ionic Au+ or Au(S2O3)2–3 as the capturing agent. Results are explained on the basis that in the absence of free heavy metal ion ( i.e., with the Pb[TA]2 or Au[S2O3]2–3 complex), AcDiS combines with AChE at both the anionic and esteratic sites, whereas, in the presence of Pb2+ or Au+, attachment of the substrate occurs only at the esteratic site of the enzyme. Results similar to the former type were obtained when the bis-(thioacetoxy) aurate (I) complex (Au[CH3COS]2– or Au[TA]2– served as both substrate and capturing agent. With both the AcDiS-Au(S2O3)2–3 and Au (TA)2– methods, extremely fine localization of AChE was obtained at the MEP's by electron microscopy.

Electron microscopic localization of acetylcholinesterase and nonspecific cholinesterase at the neuromuscular junction by the gold-thiocholine and gold-thiolacetic acid methods

By means of the gold-thiocholine (AuThCh) and gold-thiolacetic acid (AuThAc) methods, it has been demonstrated electron microscopically that acetylcholinesterase (AChE) is located at the prejunctional axoplasmic membrane and the postjunctional sarcoplasmic membrane, including the full lengths of its invaginations, at the motor end plate of mouse intercostal muscle. Nonspecific cholinesterase (ChE) is present in relatively low concentrations at the same sites, and in greater concentrations in the teloglial Schwann sheath cells. Significant amounts of reaction product appeared in the junctional cleft only after prolonged incubation with both methods. The identification of AChE and ChE was confirmed by the use of appropriate concentrations of several selective inhibitors. In confirmation of previous studies by light microscopy, the AuThCh method is more specific for AChE and ChE, whereas the AuThAc method allows greater accuracy of localization.

Classification on the basis of conditional cues

Subjects were presented with signals from two sources, either simultaneously or successively. The signal from one source, the “cue” signal, provided information about the type of classification to be made; the signal from the other source provided the data for the classification. Reaction times were recorded from the moment of presentation of the second signal to the moment the subject pressed the appropriate response key. By varying the order of presentation and the time interval between cue and data signal, the time required for the subject to select the appropriate dimension of variation in the data signal was examined.

When the cue signal preceded the data signal, the results were consistent with consecutive sequential processing of the two signals. When the data signal preceded the cue signal a further source of delay was evident. It is suggested that this results from a type of intermittency in which processing of irrelevant aspects of the data signal holds up the analysis of the cue signal.