Polarization-vortex-driven second-harmonic generation.

Polarization vortices exist in the focus of a class of vector beams, the lowest order of which possess full vector symmetry about the axis of propagation of the beam. At high numerical apertures these beams are known to exhibit large, local, longitudinal fields in the focal region. At an interface these fields can be many times stronger than the largest available transverse component and are therefore candidates for a variety of different experiments in surface physics. The observation of vortex-driven surface second-harmonic generation at smooth metal and semiconductor surfaces and thin films is reported. By comparing the response to that of a purely transverse field, we show that the smooth surface responds primarily to the longitudinal field component.

Longitudinal field modes probed by single molecules.

We demonstrate that a strong longitudinal, nonpropagating field is generated at the focus of a radially polarized beam mode. This field is localized in space and its energy density exceeds the energy density of the transverse field by more than a factor of 2. Single molecules with fixed absorption dipole moments are used to probe the longitudinal field. Vice versa, it is demonstrated that orientations of single molecules are efficiently mapped out in three dimensions by using a radially polarized beam as the excitation source. We also show that there is no momentum or energy transport associated with the longitudinal field.

Nonperturbative analysis of cross coupling in corrugated metal films.

There has been a recent renewal of interest in anomalously high energy transfer through otherwise opaque metal film geometries. One of the earliest such systems, that of surface plasmon cross coupling in a sinusoidally corrugated continuous metal film, was studied by Gruhlke et al. [Phys. Rev. Lett. 56, 2838 (1986)]. We show that it is possible to use a nonperturbative method to accurately predict this coupling, and we use this method to analyze both intrinsic coupling in symmetric structures and grating-assisted cross coupling in asymmetric structures.

Interference imaging for aspheric surface testing.

Peak-valley accuracy of lambda/20 over a range of 2lambda is not unusual in an interferometric null test. For the larger dynamic ranges of a nonnull test, however, the fringe-imaging optics degrades the accuracy. We classify the errors introduced and analyze them in the context of both general and third-order aberration theory. We can predict the measurement error from known interferometer parameters, and we illustrate this for a single mirror. The errors are tabulated for the specific case of a fourth-order asphere with 100 mum of sag. We show that the third-order approximation is comparable with exact ray-trace results for this case.

Measurement and calibration of interferometric imaging aberrations.

Phase-shifting interferometry is the standard method for testing figure error on optical surfaces. Instruments measuring spheres and flats are readily available, but the accurate measurement of aspheres requires null correction. One problem with the general (nonull) testing of aspheres is the loss of common path. Systematic errors are introduced into the measurement by the fringe imaging optics. The sources and types of error are reviewed, as well as their effect on a wave-front measurement. These nonnull errors are predicted generally, with third-order analytic expressions derived for a tilted or a defocused test surface. An interferometer is built to test the expressions. The imaging system is a single lens, nominally image telecentric. Measurements are performed on a test surface defocused from -5 to 5 mm. The resulting measurement bias is shown to be in good agreement with third-order aberration theory predictions.

Violent substance abusers in domestic violence treatment.

Although substance abuse is frequently encountered in men receiving services in violence treatment settings, systematic study of these 'dual-problem' men has lagged. This study had two main objectives: (1) the characterization of psychoactive substance abuse disorders in a naturalistic sample of men in domestic violence treatment; and (2) clarification of the role of substance abuse on the sociodemographic, personality, psychosocial, and abuse characteristics of dual-problem men. Fifty-three adult men who were attending domestic violence treatment were recruited. They were administered the Addiction Severity Index, the Conflicts Tactics Scale, Structured Clinical Diagnostic Interview, the 16PF and the Symptoms Checklist-90. Partners, when available, were asked to provide corroboration. Sixty-three percent of the men had a current diagnosis of psychoactive substance abuse or dependence, while 92.5% had a lifetime diagnosis. Of the former, the majority was diagnosed as multiply dependent on alcohol and other drugs. As the severity of the substance abuse increased, so too did the dangerousness and frequency of abusive behaviors. Moreover, dual-problem men reported more hostility, apprehension, frustration and suspiciousness and past arrests than did their violence-only cohorts as well as a history of multiple (unsuccessful) treatments for substance abuse. These findings suggest that the trend toward multiple drug complaints seen in other clinical milieus is also being confronted in conjugal violence settings. In addition to the greater therapeutic challenge such dual-problem men present, these findings speak to the need to investigate integrated treatment approaches to improve the outlook of men grappling with both conjugal violence and multiple substance abuse problems.

Subjective appraisal of problem severity and the ASI: secondary data or second opinion? Addiction Severity Index.

The Addiction Severity Index is a popular research and clinical tool for the characterization of individuals grappling with substance abuse problems. For research, use of the seven objectively calculated composite scores of problem severity is recommended. In contrast, clinical use of the instrument relies more upon its subjectively derived interviewer and client severity rating scores. However, little systematic research has looked at the comparability of these two sources of client data. This study compared the objective and subjective scores of the ASI of male (n=141) and female (n=58) clients entering substance abuse treatment. In addition, clients' narratives about their most worrisome problems were recorded and put to content analyses. While significant correlations were found among the various subjective indices, little relationship could be discerned between the objective composite scores and any of the subjective indices derived from either the ASI or the clients' narratives. As the focus of outcome research shifts from objective client and treatment characteristics to a better understanding of the process of intervention, empirical characterization of substance abuse treatment outcome may be enriched by the inclusion of subjective data that taps into the client's own perceptions of problems and treatment efficacy in addition to more objective sources of data.

The incidence and characteristics of violent men in substance abuse treatment.

Linkage between marital violence and substance abuse has been noted in men seeking treatment for substance-use disorders. The present study examined (1) the incidence of family violence in men admitted into substance abuse treatment; (2) the psychosocial characteristics associated with marital violence; and (3) the comparability of violent substance abusers to their treatment cohorts. Fifty-nine men in substance abuse treatment involved in a significant relationship in the past year were assessed for substance abuse, family violence, psychosocial functioning, and personality attributes. Fifty-eight percent of men reported at least one incident of physical familial violence in the past year, while 100% of the men reported having engaged in psychological abuse in the past year. Additionally, greater violence was associated with interpersonal insensitivity, hostile outbursts, and poorer overall functioning independent of substance abuse. Finally, violent male substance abusers reported significantly more hostility, suspiciousness, projection of blame, and interpersonal inadequacy than did the less violent substance abusers. These findings suggest that, in drug-treatment settings, systematic objective screening for family violence is routinely called for.

The effect of vocalization on the heart rate response to mental arithmetic.

The heart rate (HR) responses to verbal and nonverbal mental arithmetic tasks were studied in twenty undergraduate males. The two problem-sets were presented in counterbalanced order to the subjects. Greater HR responses to verbal, in contrast to nonverbal, arithmetic were only observed when the verbal arithmetic task was presented first. The peak (maximal) HR response was also the highest when the verbal arithmetic was presented first to the subjects. It is concluded that physiological or mechanical components of vocalization do not affect the HR response to mental arithmetic. However, certain psychological components, including test-anxiety or motivation, may increase the HR when subjects have to provide verbal answers during a first exposure to a challenge. This effect dissipates during the second exposure to the challenge due to habituation.

The role of spouses of substance abusers in treatment: gender differences.

Studies exploring gender differences among substance abusers in treatment have been fairly consistent in finding that females who enter treatment express more severe psychological and psychosocial disturbances than males, despite presenting with shorter and less intense substance abuse histories. However, strands of evidence suggest that the presence of a spouse, generally perceived as an asset in the treatment of the substance abuser, may have different implications for females than for males. In order to clarify this issue, 67 male and 18 female married substance abusers in treatment and their spouses were questioned on their substance use and psychological and social functioning. Similar to other studies, the female substance abusers reported greater disturbance on dimensions of employment and psychological functioning, but less severity of alcohol abuse. Comparison of male and female spouses, however, revealed that male spouses were likely to present with the following characteristics: (1) more symptoms of substance abuse and depression, (2) less overall physical well-being, and (3) to be less inclined to help others or be involved with their children than the female spouses. These findings are consistent with the view that the process of substance abuse is telescoped in females and is associated with more disturbed functioning in women on admission to treatment than in men. However, contextual differences--specifically in terms of availability of spousal support--may contribute significantly both to the understanding of differences in female versus male substance abusers in treatment as well as to the development of guidelines for adapting treatment based on gender.

Alcoholics also dependent on cocaine in treatment: do they differ from "pure" alcoholics?

Although individuals who exhibit both alcohol and cocaine dependency are seen increasingly in traditional alcoholism rehabilitation settings, their comparability with "pure" alcoholics is unclear. Sociodemographic, psychological, cognitive, and substance abuse status were, therefore, monitored in a group of alcoholics (n = 64) versus a group of cocaine dependent alcoholics (n = 82) on admission and just prior to discharge from 28-day multimodal treatment settings. At admission, cocaine-dependent alcoholics were younger, more likely to be unmarried, have more extensive substance use histories as well as more frequent prior treatments than "pure" alcoholics. Additionally, members of both groups exhibited abnormalities on psychological indices. Both psychological and cognitive indices revealed significant between-group differences which subsequent analyses found to be a confound of the marked age discrepancy between groups. From admission to discharge, scores on both psychological and cognitive indices declined significantly in both groups. Urine assay data revealed a greater tendency for cocaine-dependent alcoholics to relapse during treatment. While the psychological and cognitive data largely argue for the comparability of groups of patients classified as "pure" alcoholics with those who are dependent on both alcohol and cocaine, the latter group may have more difficulty in achieving abstinence during treatment. The interpretability of behavioral indices gathered only at treatment admission is questioned.

Alcohol and cocaine abusers 6 months after traditional treatment: do they fare as well as problem drinkers?

Problem drinkers (N = 49) and individuals presenting with both alcohol and cocaine problems (N = 51) admitted to a traditional 28-day alcoholism treatment milieu were compared on their psychosocial, psychological, neuropsychological functioning and substance abuse at admission as well as at six months posttreatment follow-up. On admission, alcohol and cocaine patients were younger, more likely to live alone or with their family of origin, to report having started using alcohol at an earlier age, to have fewer alcohol-related problems and to have fewer years of but more diversity in their substance abuse than the alcohol-only patients. Otherwise both groups were more similar than different on psychosocial, psychological and neuropsychological dimensions. At six-months posttreatment, both groups showed similar improvement on most dimensions of functioning measured. However, a significantly greater proportion of the alcohol and cocaine abusers admitted to having relapsed in the previous six months, reported significantly fewer average days of abstinence than the alcohol group since terminating treatment, and were more likely to present urine specimens indicative of recent substance abuse at the six-month follow-up interview. Thus, traditional approaches to alcoholism treatment may be less effective in establishing abstinence for individuals with both alcohol and cocaine problems. Adaptations to treatment to reduce the risk for relapse faced by alcohol and cocaine abusers in such milieu are discussed.

Aerobic fitness does not influence directly heart rate reactivity to mental stress.

Thirty-seven aerobically high and low fit male and female university students, selected on the basis of estimated aerobic capacity, completed a set of hard as well as a set of easy mental arithmetic tasks for 90 seconds in a counterbalanced order with a 10 min rest period between the tasks. Heart rate (HR) reactivity to either task was independent of aerobic fitness level. Although subjectively rated as more challenging, HR responses to the hard arithmetic task were not greater than that seen to the easy task. These results do not support the conjecture that aerobic fitness level may mediate HR response to acute mental challenge. The overall implications of these results are discussed in relation to the literature concerning aerobic fitness and mental stress.

Optical emission from impurities within an epitaxial-silicon optical waveguide.

Beryllium pairs form an isoelectronic complex in crystalline silicon that can bind an exciton. At sufficiently low temperatures, this bound exciton radiates in a narrow line near the wavelength lambda = 1.15 microm. We report the observation of optical confinement of this bound-exciton emission from beryllium impurities introduced, by ion implantation, into an epitaxial-silicon optical waveguide.

Electron-nuclear double resonance of copper complexes of human transferrin.

Electron-nuclear double resonance (ENDOR) spectroscopy has been used to study ligand and copper hyperfine interactions in Cu(II) complexes of human transferrin. A nearly isotropic superhyperfine interaction of the Cu(II) spin with a single 14N nucleus was identified, and the principal values of its tensor were estimated. All principal values of the copper hyperfine tensor were also directly measured for the first time. Resonances from at least two exchangeable protons were observed, but their origin could not be ascertained. At physiological pH, and in the presence of bicarbonate, ENDOR spectra of the two metal-binding sites were virtually indistinguishable.

Electron-nuclear double resonance of the hydrogen peroxide compound of cytochrome c peroxidase: identification of the free radical site with a methionyl cluster.

The results of electron-nuclear double resonance and electron paramagnetic resonance (EPR) studies on the hydrogen peroxide compound of yeast cytochrome c peroxidase are inconsistent with previous proposals for the source of the EPR signal in this compound, in particular with its identification with an aromatic amino acid radical such as would arise by oxidation of a tryptophanyl side chain. The present observations lead us to propose that the EPR signal is associated with a cluster containing at least one methionine and in which proximate side chains share the charge created by loss of one electron.

Matching with a trio of concurrent variable-interval schedules of reinforcement.

A trio of concurrent variable-interval schedules of reinforcement was arranged according to a changeover-key procedure, including a changeover delay of 1.5 sec. The three schedules provided a combined maximum reinforcement rate of 45 reinforcements per hour. With that restriction, the nine experimental conditions included several combinations of variable-interval schedules, sometimes including extinction. The pigeons matched relative response rate and relative time to relative reinforcement rate. Relative time appeared to match some-what better than relative response rate. Performance adjusted rapidly from one experimental condition to the next, whether the change involved two or all three schedules of the concurrent trio.