No abstract

The chemical reaction of ozone with decanethiol monolayers on Au(111) was characterized using X-ray photoelectron spectroscopy and scanning tunneling microscopy. Our results show that exposure to ozone results in oxidation of the thiol terminus. The reaction initiates at the domain boundary network of the alkanethiol monolayer and propagates into the domains. Above a threshold surface oxygen content, the monolayer converts to a two-dimensional fluid that can subsequently recrystallize to a commensurate monolayer of partially oxidized thiol. Further exposure to ozone results in conversion of the monolayer to a fluid phase and a 10% to 30% expansion of the Au lattice at the Au−thiol interface with concomitant formation of Au islands. Our results demonstrate that crystallographic defects in monolayer films can play an important role in their chemical reactions.

Scent marks are important mediators of territorial behaviour and sexual selection, especially among mammals. The evolution of compounds used in scent marks has the potential to inform our understanding of signal evolution in relation to social and sexual selection. A major challenge in studies of chemical communication is that the link between semiochemical compounds and genetic changes is often unclear. The major urinary proteins (MUPs) of house mice provide information on sex, status and individual identity. Importantly, MUPs are a direct protein product of genes, providing a clear link between genotype and phenotype. Here, we examine the evolution of urinary protein signals among house mice and relatives by examining the sequences and patterns of mRNA expression of Mup genes related to urinary scent marks. MUP patterns have evolved among mouse species both by gene duplication and variation in expression. Notably, protein scent signals that are male specific in well‐studied inbred laboratory strains vary in sex‐specificity among species. Our data reveal that individual identity signals in MUPs evolved prior to 0.35 million years ago and have rapidly diversified through recombining a modest number of amino acid variants. Amino acid variants are much more common on the exterior of the protein where they could interact with vomeronasal receptors, suggesting that chemosensory perception may have played a major role in shaping MUP diversity. These data highlight diverse processes and pressures shaping scent signals, and suggest new avenues for using wild mice to probe the evolution of signals and signal processing.

No abstract

The high resolution IR spectrum of cyclobutane in a supersonic molecular beam was obtained for the region of 2981 to 2991 cm-1. The spectrum reveals four overlapping bands suggestive of vibrational mode coupling in the C-H stretching region. Ground -state combination differences demonstrate that these bands__ Ac_:e io For originate from 2 different ground states, the symmetric and INT IS CF-., asymmetric ring puckering states. Evidence of vibrational mode, ' coupling is present in all four bands. The coupling depends on' J both J and the symmetry of the puckering state. A model:. coupling scheme involving two qualitatively different types of y couplings is developed to explain the observed spectrum.. -----------Symmetry restrictions and the Interaction between molecular" rotation and ring puckering qualitatively accounts for the[ dramatically different coupling behavior between the two ring/ puckering states.

Abstracr--'Ihis paper eolLfists of fwr seetioas c o v e 1) basic principles of noise mersPrement, 2) the switching radiometer, 3) a survey of noise so~~lces, and 4) concepts of noise factor and noise temperature. The f h t sectioopresentsbPsiCfom~lsediu~rdiometen.Thesecood disclases the switching rrdiometer, brieUy traciug its development and usage in the shodads field. lEe third sectioa surveys the development of hot and cold t h e d noise s(w~es, noise diodes, and grsdischnrge noise generators.The last sectioa presents and disasses the basic dehitiom of receiver noise perfomme.

No abstract

The school psychologist may be regarded as a professional agent who not only measures a student's ability and interprets his scores, but also communicates a child's achievements to his parents, to his teachers and to the school administrators. Recommendations concerning a child's classroom assignment, be it to a class for educable mentally retarded, emotionally disturbed or normals, certainly will affect his destiny. Many a psychologist, with good justification, places great stock in intelligence test results. One of the consistently stable predictors of scholastic achievement has been the intelligence test score. By far, the most frequently used type of intelligence test is the paper and pencil, objectively keyed measure. This type of test is seriously limited in its ability to measure that portion of the school population that demonstrates deficits in certain motor or complex functions, such as reading. Therefore, psychologists have administered the individual test of ability to assess the marginally able student. One of the two tests popularly used for such purposes is the Wechsler Intelligence Scale for Children (WISC), the subject of the present study.Recommendations that stem from individual tests of ability are largely prognostic in nature. Like other predictiqn situations, their utility depends on the validity and reliability of the ability and achievement tests. With respect to validity, Zach (1966) brings to our attention an alternative explanation of the high ability and achievement relationship, namely, children whose obtained ability scores are low are placed in classes for slow learners and foqa variety of reasons perform poorly in class. Hence, poor performance may be due to factors confounded with low ability classroom placement and fulfills the poor performance prophecy.The focus of the present study is on the second of the two points made earlier, namely, reliability. Watson (1967a, 196713) found that psychologists showed low interjudge agreement of the Draw-A-Person Test. He reported that diagnostic impressions based on DAP alone were neither valid nor consistent between raters. In addition, the accuracy of the judges' diagnoses was only slightly above chance and uncorrelated with hospital-record impressions. In an investigation of factors that affect agreement among clinicians, Huff (1966Huff ( , 1967 reported that interjudge agreement was affected by almost every variable manipulated. Of the several variables tested, ratings of intelligence based on WAIS scores provided the highest reliability.Satler and Winget (1970) studied the effect of WAIS scripts on the scoring of WAIS protocols. Accomplices memorized responses to Comprehension, Similarities, and Vocabulary items. They found that more credit for ambiguious responses was given to Ss believed to have high IQs than to those believed to have lower IQs, which suggests a constant error in the scoring of this test. Massey (1965) urged the adoption of a more uniform scoring system for the Wechsler scales. He found that the range of scores of c...