Search

We measured binocular rivalry between dichoptic, orthogonal, sinusoidal gratings both having spatial frequencies of 0.5, 1, 2, 4, 8 or 16 c deg-1 in fields ranging from 0.5 to 8 deg of visual angle in diameter. Total time that one or the other grating was exclusively visible had an inverted U-shaped relationship with spatial frequency, with the peak shifting to coarser spatial frequencies as the field size increased. We computed for each spatial frequency the maximum field size over which a criterion duration of exclusive visibility would spread. When expressed as areas, these sizes were inversely proportional to spatial frequency. This dependence of rivalry on spatial frequency is similar to those for stereopsis and fusion, consistent with the notion that all three binocular phenomena have a common mechanism.

To test whether the binocular contour rivalry mechanism is tritanopic, we presented isoluminant, rival stimuli visible only via the short-wavelength-sensitive (S) cones. We stimulated only the S cones with violet gratings superimposed on a bright yellow field that adapted the responses of the middle- and long-wavelength-sensitive (M and L) cones. We found that an S-cone grating presented to one eye rivalled with an orthogonal grating presented to the other. Rivalry persisted over a range of luminances and contrasts of the S-cone stimuli, and was greater than could be accounted for by nonrival fading. The spatial spread of rivalry from S-cone stimuli is similar to that for the same stimuli when visible also to the M and L cones (luminance stimuli). We found that an S-cone stimulus would rival with a luminance stimulus, and exploited this to determine the equivalent luminance contrast of S-cone stimuli by putting them in a rivalry competition with luminance stimuli. For rivalry, the equivalent luminance contrast of isoluminant, S-cone stimuli is much less than their S-cone contrast. The existence of rivalry with isoluminant stimuli, along with earlier evidence that such stimuli can support stereopsis, challenges the view that an achromatic channel alone drives certain higher level functions such as depth perception.

The management of 255 surgically proven cases of ectopic pregnancy, treated at a teaching hospital over a 5-year period, was retrospectively reviewed to determine the proportion of cases where the diagnosis was 'missed' at initial presentation. Thirty-one patients (12%) had presented and been discharged with an incorrect diagnosis, then subsequently readmitted for definite treatment of a tubal ectopic pregnancy. In this group, the mean time from initial presentation to definitive surgery was 8 days. Ten of the 31 women with 'missed' ectopic pregnancies (32%) underwent salpingectomy, whereas the rate of salpingectomy in those women whose ectopic pregnancy was correctly diagnosed at first presentation was 19.5% (44 of 224). We conclude that delays in the diagnosis of ectopic pregnancy may be associated with an increased rate of salpingectomy, which may in turn reduce prospects for future fertility, a finding not previously canvassed in the literature. The factors contributing to misdiagnosis of ectopic pregnancy are discussed and compared with those reported in other studies.

Lehmkuhle and Fox [(1976) Vision Research, 16, 428-430] reported that interocular transfer (IOT) of a translational motion aftereffect (MAE) was greater if the non-adapting eye viewed an equiluminant field than if it viewed a dark field. They recommended equiluminant occlusion of the non-adapted eye when measuring IOT of aftereffects. We tested this proposal in three experiments. First, we assessed IOT with equiluminant and dark occlusion for three different classes of aftereffects. Although transfer was greater with equiluminant occlusion for the translational MAE, there was no significant difference in the amount of transfer for the tilt aftereffect or the contrast threshold elevation effect. Second, we tested the hypothesis that spuriously large IOT could be the result of an aftereffect from tracking eye movements in the non-adapting eye. When potential tracking movements were reduced by using rotating spokes, a rotating spiral or contracting concentric circles, there was a corresponding reduction in the occlusion-dependent transfer. Third, we found that luminance shifts had no influence on the amount of transfer when all contours were eliminated from the non-adapting eye. We conclude that the type of occlusion used for measuring IOT of the translational MAE is important only when visible contours in the non-adapting eye contribute to the adapting process.

Purpose: To use issues identified by students in order to establish an experience- and evidence-based approach to medical ethics education., Method: A total of 628 sophomore and senior students at the State University of New York at Buffalo School of Medicine and Biomedical Sciences were asked to identify incidents during their clinical training that had raised ethical concerns. The sophomores were surveyed during two time periods: 1979-80, and 1991-92 and 1992-93; the seniors were surveyed in 1991-92 and 1992-93. Responses were analyzed and categorized through content analysis., Results: In all, 249 students (45% of the sophomores and 20% of the seniors) responded. The categories of issues identified were professional norms, limits of intervention, defensive shielding of professional colleagues, respect toward patients, communication, and student boundaries (situations where the student feels uncomfortable). The most frequently reported incidents reflected the students' perceptions of lapses in level of care (under- or over-treatment), communication, respect toward patients, and maintenance of professional norms. The seniors and the 1979-80 sophomores reported respect toward patients as an issue less often than did the 1991-92 and 1992-93 sophomores. The seniors most often identified concerns raised over limits of intervention and resource allocation., Conclusion: The differences between the responses of the sophomores and seniors tend to support other research suggesting a retardation of moral sensitivity in the course of medical education. It may be that clinical teaching and faculty behavior model values at odds with what is taught in the classroom. Ethics education should focus on issues relevant to students' experience.

Objective: The aim of the study was to identify predictors of first-contact care in a population of poor urban residents., Methods: Information from a community health needs survey was used for the study. The sample included adult residents in five urban census tracts with a large proportion of Puerto Rican Hispanics. Potential predictors included social characteristics, source of health insurance, perceived health status, number of chronic diseases, use of alternatives to medical care, smoking status, and problems with alcohol use., Results: A total of 826 household interviews were completed for a participation rate of 78% among eligible households. Individuals with no health insurance were six times more likely to lack a source of first-contact care, compared with those who have traditional indemnity insurance. Those who only had Medicaid were four times more likely to lack a source of first-contact care. Respondents involved in Medicaid-managed care programs had similar access to first-contact care as those with commercial insurance. Individuals who reported problems with alcohol were three times more likely to lack a source of first-contact care., Conclusions: Health insurance is an important predictor of access to first-contact care for poor urban residents. Those who identify problems with alcohol and African-Americans have additional difficulty with access to first-contact care.

Dodwell and O'Shea's [(1987) Vision Research, 27, 569-580] conclusions that contingent coloured aftereffects (CAEs) depend on gobal pattern organization were investigated in four experiments. In Expt 1, we replicated findings that CAEs can be induced with complex patterns (concentric circles; radial spokes) under conditions of systematic eye movements. Contrary to Dodwell and O'Shea's argument that eye movements should uniformly cancel local orientation-colour contingencies, leaving only global effects, we reduced CAE magnitude by halving the diameter of the test stimuli. This suggests that cancellation did not occur uniformly over whole patterns, and that CAEs observed on these patterns are the residuals of uncancelled local orientation-colour contingencies. In Expt 2 we used central-fixation induction procedures to demonstrate that it is possible to induce CAEs with randomly-organized and locally-orthogonal orientation components. These findings are inconsistent with Dodwell and O'Shea's failure to observe CAEs under these conditions, and with their conclusion that global organization is necessary for CAE induction. However, CAEs induced with randomly-organized components were significantly weaker than those induced with globally-organized components. We examined the contribution of global organization in two additional experiments. In Expt 3 we induced CAEs with randomly-organized components under conditions in which the need for central fixation was removed, and found that CAE strength was directly related to the organization as well as the density of local-orientation components. In Expt 4, we found that the global organization of local-orientation components enhanced CAE strength only in regions away from the edges of these components: pattern organization did not affect the strength of CAEs at edges. We interpret these findings as evidence that CAEs may involve separate edge- and spread-colour components, and conclude that such components may account for observations previously attributed to global pattern geometry.

Hypothalamic neuropeptide Y (NPY) and 5-hydroxytryptamine (5-HT) may interact to regulate food intake. This study investigated the effects of the 5-HT reuptake blocker and secretagogue D-fenfluramine (D-FEN) on preproNPY mRNA abundance in the hypothalamic arcuate nucleus (ARC) of free-feeding and food-deprived (FD) rats in two treatment regimens. ARC preproNPY mRNA levels were significantly increased in FD rats, to the same extent as in combined FD/D-FEN animals. D-FEN treatments producing different-sized reductions in food intake (and body weight) produced corresponding changes in ARC preproNPY mRNA abundance. These findings suggest that ARC preproNPY mRNA levels are not directly altered by D-FEN, and that D-FEN-induced anorexia does not involve effects on the hypothalamic NPY system at the level of NPY gene transcription.

Tubal pregnancy can be safely and effectively managed by MTX or CO2 laparoscopic salpingotomy techniques. Methotrexate may be superior because of its simplicity, requiring only basic laparoscopic skills, whereas laparoscopic salpingotomy necessitates operative laparoscopic input.

The detailed experience of one international student provides a case history in the use of college health services. His journey through the campus health center and outside referrals reveals important facets of student healthcare. It also offers some insights into foreign students' feelings as they contrast their health encounters with expectations carried from home. Four commentaries on the case attempt to draw inferences and to explain from various points of view what the student found in the course of seeking a diagnosis for rectal bleeding.

One consequence of aerial perspective is that far objects have lower contrast than near objects. We tested the efficacy of contrast as a cue for depth perception by measuring the apparent, relative depth of two areas that differed in contrast with a background and in size. We tested monocularly and binocularly. Differences in contrast were achieved by making the areas different in luminance, than varying the luminance of the background. Subjects reported that the area having lower contrast with the background appeared farther than the area having higher contrast. Even when size opposed it, contrast continued to have a significant effect on depth perception. Monocular observation yielded larger apparent depth than binocular observation. Contrast is an effective depth cue in the absence of any other depth information. We suggest that contrast acts as a pictorial depth cue simulating the optical effects of aerial perspective.

In 32 women with unruptured tubal ectopic pregnancies we undertook conservative laparoscopic treatment [local injection of 20 mg methotrexate (n = 18), laser salpingotomy (n = 14)]. The results of serial quantitative beta HCG measurement were followed until either a negative level was reached or until rising levels necessitated alternative/additional therapy. Plateaued values of beta HCG were observed in both the successful (n = 16) and the unsuccessful cases (n = 5). To test the hypothesis that daily variation in the assay could account for some or all of the observed plateaued results in successful cases, the sera were retested serially on the same 'run'. In only one case did laboratory variation account for the observed plateau. The clinical implications of the findings are discussed. We conclude that serially monitored beta HCG results after conservative treatment of ectopic pregnancy may show plateaued values without indicating failure of treatment.

Purpose: To compare binocularity in central and peripheral vision of people with early-onset strabismus and people with normal binocular vision., Methods: Ten subjects with early-onset strabismus, and nine subjects with normal binocular vision were tested. To assess binocularity, interocular transfer (IOT) of a rotary movement aftereffect (MAE) was measured. The MAE stimuli were either confined to the central 2.8 degrees of the visual field or were presented 10 degrees into peripheral vision., Results: In peripheral vision, there was no significant difference in IOT for the two groups of subjects. In central vision, there was a significant decrease of IOT in subjects with early-onset strabismus. Their IOT was, however, significantly greater than zero., Conclusions: Early-onset strabismus appears to spare binocularity in peripheral vision but reduces it in central vision. It does not abolish binocularity assessed by IOT of MAE, suggesting that some binocular connections survive early-onset strabismus, even in central vision.

A study is reported of human binocular rivalry and fusion over a range of luminances from scotopic to photopic. At scotopic light levels, rivalry alternations were very slow and complete. Suppression spread over much larger areas of the visual field than at photopic light levels. As luminances decreased from photopic to scotopic levels there was a rod-cone break for binocular rivalry. Mean suppression durations became abruptly greater as light levels dropped below those allowing the cones to be active. Horizontal disparities allowing fusion were 4 to 6 times greater at scotopic than at photopic light levels. Binocular vision at scotopic luminances was sluggish and of low resolution. It is as though connections to, and within, binocular vision are changed when light levels allow only rod input.

Cholecystokinin (CCK) has been suggested to mediate satiety in a number of non-primate species via its peripheral actions as well as a possible central mechanism involving magnocellular and parvocellular oxytocin release. Quantitative in vitro autoradiography employing [125I]-Bolton-Hunter labelled CCK-8S ([125I]-CCK-8S) was used to examine the distribution and density of CCK receptors in sections of brain from normal rats and rats deprived of food, water or both food and water for 4 days. In food-deprived rats, specific [125I]-CCK-8S binding was reduced by 64 +/- 5% in the hypothalamic supraoptic nucleus (SON) and by 44 +/- 13% in the paraventricular nucleus of the hypothalamus (PVN). In contrast, water deprivation increased binding of [125I]-CCK-8S by 128 +/- 15% in the SON and by 196% +/- 24% in the PVN, while combined food and water deprivation produced smaller increases in both nuclei (30 +/- 5% and 98 +/- 26% in SON and PVN respectively). Changes in receptor density in the PVN appeared to be most prominent in the magnocellular (especially oxytocin-rich) subdivisions. None of the treatments employed produced changes in [125I]-CCK-8S binding in the ventromedial hypothalamic nucleus or the reticular thalamic nucleus. Both CCK-A and CCK-B receptor subtypes were visualized in the nucleus of the solitary tract and the area postrema of normal rats, but levels of binding to both of these subtypes were unaffected by the experimental treatments. These selective alterations demonstrate the plasticity of CCK receptors in the SON and PBN, and are probably associated with changes in the level of neurochemical activity of magnocellular oxytocinergic neurones in these areas. These results, together with reports of changes in the level of CCK synthesis in cells of the SON and PVN after hyperosmotic stimuli, suggest that CCK may act in an autocrine fashion on these neurones and that both CCK receptors and peptide levels are altered in the same direction following cellular activation or inhibition.

Most former cigarette smokers in the United States have stopped without formal assistance. However, a large proportion of smokers desire and seek help other than by attending formal programs. It is important to recognize what factors are likely to influence the effectiveness of smoking cessation attempts among these persons. The authors report results of a prospective cohort study of 1,552 smokers who called a stop smoking hotline to request self-help smoking cessation information. The participants were classified into three groups based on reports at the 6-month followup: 242 quitters, 497 recidivists, and 813 nonquitters. Baseline and followup data were used to evaluate three comparisons: quitters versus nonquitters, quitters versus recidivists, and recidivists versus nonquitters. Nonquitters appear to be less motivated and more doubtful of their abilities to quit successfully compared with the other two groups. Quitters appear to live in a supportive environment for smoking cessation. Heavier smokers are more hesitant to try to quit, but once they make an attempt they are as likely to succeed as lighter smokers, when other factors are kept constant. Efforts to promote environments supportive of smoking cessation are likely to result in a larger number of successful quitters. Similarly, efforts to strengthen motivation and belief in personal ability to quit are likely to encourage more nonquitters to attempt to stop smoking. Finally, it appears that some smokers need a previous quit attempt before they are able to maintain cessation successfully.

L-Glutamate is known to function as a major excitatory neurotransmitter in the mammalian central nervous system, and recent reports suggest the existence of receptors for glutamate in several peripheral tissues. In the present study, the characteristics of the binding of [3H]L-glutamate to sections of bovine adrenal gland were studied, and the localisation of this binding was investigated in adrenal glands from cow, dog, rat and guinea pig. In addition, the effects of glutamate on catecholamine release from the perfused isolated bovine adrenal gland were investigated. Binding of [3H]L-glutamate to slide-mounted sections of bovine adrenal gland was of high affinity (Kd 0.4 microM), rapid, saturable, reversible, stereospecific and to a single population of sites. The pharmacological profile of this binding site appeared to be unique, and did not correspond to any of the central receptor subtypes for glutamate so far identified. In the adrenal gland of the cow, rat and guinea pig, the binding density of [3H]L-glutamate was higher in cortex than medulla, while this pattern was reversed in the canine adrenal gland. Glutamate had no effect on the basal secretion of noradrenaline or adrenaline from the perfused isolated bovine adrenal gland, and neither glutamate nor the glutamate receptor antagonist kynurenate altered the nicotine-stimulated release of these catecholamines. These results suggest the existence of a novel peripheral binding site for glutamate in the adrenal gland. The differential autoradiographic localisation of this binding site in the adrenal glands of the various species studied may reflect different functional properties of glutamate in these species, and suggests possible roles for glutamate in the modulation of adrenal function.

This matched case-control study was conducted in Western New York. The smoking, alcohol consumption, dental hygiene and diet of 290 cases were compared with those of 290 sex-, age-, and neighbourhood-matched controls. The results confirm earlier findings that cigarette smoking and alcohol consumption impart substantial risk of oral cancer. The results also confirm that poor oral hygiene increases the risk of oral cancer, although this effect is much smaller than those of cigarette smoking and alcohol consumption. The results suggest that, of macronutrients, intake of fat is more likely than those of protein or carbohydrate to be related to risk. Of micronutrients, calcium, sodium, riboflavin and retinol are associated with risk, while thiamin, niacin, and dietary fibre are associated with decreased risk. Although patterns of dietary effects are discernable, these effects are in general much weaker than are those of smoking and alcohol consumption.

This paper presents results from psychophysical experiments on human binocular rivalry in central and peripheral vision. Results show that the incidence of periods of exclusive visibility of a given eye's rival target increased with decreasing target size, and for a given sized target exclusive visibility increased with retinal eccentricity. Control measures confirmed that these results were not attributable solely to reduced peripheral acuity, to Troxler's effect, or to spatial frequency. We computed the minimum-sized stimulus that would lead to a criterion level of exclusive visibility of one or the other eye; this we term the spatial zone of binocular rivalry. The change in estimated size of spatial zones of rivalry with eccentricity compares favorably with estimates of human cortical magnification. We propose a model that assumes concentrically organized zones of rivalry. These zones do not function independently, but instead exhibit a high degree of mutual excitatory cooperativity. The model has multiple solutions for the foveal zone size, but the best fits predict a diameter of 5.3 or 7.3 min of visual angle; these values dovetail nicely with our empirical estimates of the foveal zone size.

The relationship between sociodemographic, biological, and prenatal care characteristics, and participation rates of pregnant women in the Special Supplemental Food Program For Women, Infants, and Children (WIC) was studied by interviewing 200 postpartum patients in a Buffalo, NY, hospital between October 1988 and January 1989. Among the 136 women eligible for the program, 94 (69 percent) participated during their index pregnancies. WIC participation was found to be highly associated with source of prenatal care and having made more frequent prenatal visits. WIC was related to having fewer children and earlier initiation of prenatal care. Multivariate analysis showed that program participation remained highly associated with the source of prenatal care and the number of prenatal visits, when combined with other factors considered, such as age, education, marital status, number of living children, and timing of initial prenatal visit. The results suggest the need for a WIC enrollment effort directed to providers of prenatal care, who would be urged to encourage women to seek early and adequate prenatal care through the program.

Objective: To test the efficacy and possible side effects of a single 20 mg dose of methotrexate injected at the time of laparoscopy, in the treatment of tubal ectopic pregnancy., Design: The study was a non-randomised non-blinded prospective clinical trial., Setting: The study was carried out at two tertiary referral hospitals., Patients: Eighteen patients with unruptured tubal ectopic pregnancies and in a stable haemodynamic condition were offered entry into the study and all of these agreed., Interventions: At diagnostic laparoscopy, 20 mg of methotrexate in 0.8 mL was injected by fine needle in or around the ectopic gestation., Main Outcome: Patients were followed up as outpatients by serial blood tests until resolution of the ectopic pregnancy was demonstrated by a return of the level of beta-human chorionic gonadotrophin to the normal range., Results: There was one failure of treatment. The ectopic pregnancy resolved in the remaining 17 patients. There were no side effects attributable to methotrexate and tubal patency was demonstrated in the eight patients tested by hysterosalpingography.

A rural family practitioner may be responsible for the general medical and obstetric needs of a closed population such as the Old Order Amish. Until recently, the Amish in southern New York State have preferred to receive obstetric care in the home from traditional Amish midwives. Acceptance of prenatal care and hospital deliveries by rural physicians appears to be increasingly frequent among Amish primiparas in southern New York State, while non-Amish in the area have been seeking these services for decades regardless of parity. This retrospective chart review examines first pregnancy outcomes of Amish (N = 39) and non-Amish (N = 145) women who delivered their babies at a rural hospital in southern New York State during a four-year period. Little difference was found between the two groups of women regarding the overall good health of their first babies. In the Amish population there was less variability in maternal age, season in which the birth occurred, labor duration, and birth weight of babies. The Amish had their first child an average of one year later than the non-Amish. While research on a larger sample will be necessary to fully explore Amish vs non-Amish variances, this study demonstrates the effect that traditions and customs of a closed society such as the Amish may have on obstetric practice.

A comparison of results of GIFT procedures using unilateral and bilateral tubal cannulation was made. There was no difference in outcome between these two methods, with the unilateral approach having some advantages over the bilateral procedure. Pregnancy rates decreased as the number of oocytes transferred was reduced.

The distribution of messenger ribonucleic acid (mRNA) encoding preproneuropeptide Y (prepro-NPY) in the hypothalamus of rats subjected to food deprivation or dehydration has been investigated by quantitative in situ hybridization. Levels of prepro-NPY mRNA in the arcuate nucleus (ARC) were selectively increased by both treatments. The very high concentration of prepro-NPY mRNA seen following 96 h of food deprivation had returned towards control levels after 24 h of refeeding. Levels of preprogalanin (prepro-GAL) mRNA throughout the hypothalamus were essentially unaffected by both regimes. These results demonstrate that hypothalamic NPY gene expression is regulated by peripheral metabolic status (and osmolality), and confirm the key physiological role of NPY in controlling ingestive behaviour.

Measures of the size of various hand parts and their viewing distance when held at arm's length were made on one hundred and eighteen undergraduate students. A simple rule of thumb can be confirmed: Visual angle of the width of the thumb held at arm's length is about 2 deg. The thumbnail subtends about 1.5 deg and the index fingernail about 1 deg in width, when both are held at arm's length. These figures are good approximations for males and females, although a significant, direct, linear relationship exists between hand-part size and the visual angle of the part at arm's length.

Patients' anxiousness over treatment is an important factor in the utilization, delivery, and outcome of health care. Patient anxiety over dental treatment is widespread and is a source of stress for both patients and dentists. This paper reports a study of how dental students cope with fearful patients they treat during training, and what tactics they believe are effective. Two classes of senior dental students at a state university (n = 127) completed a brief questionnaire that asked them to describe what they had done in a previous encounter with a nervous patient, and to assess the effect of their actions. Students estimated that almost a quarter of their patients were anxious; most believed that they themselves were made nervous by such patients. Virtually all were committed to using talk plus local anesthesia rather than more extensive, drug-oriented methods. The coping repertoire was extensive. Giving reassurance was the most prominent tactic, followed by providing information about the procedure; expressing empathy or identifying patient feelings and the source of fear; and presenting a calm manner. Most students believed their actions had at least some positive, if not a dramatic, effect. In rating the effectiveness of 10 actions a dentist can take to deal with patient anxiety, the large majority of students rated every behavior as being at least somewhat effective. The behaviors rated 'very effective' by half or more of the students included having a calm manner, demonstrating that what the patient says is taken seriously, being friendly, making the patient feel welcome, and giving moral support during the procedure.

Linear salpingotomy was performed on 16 patients using the CO2 laser laparoscopically directed. Median operating time was 60 minutes (range 40-100) and all patients were discharged on the first postoperative day. There were 4 patients in whom persistence of trophoblast activity was detected, 2 of whom were treated surgically and 2 by oral methotrexate therapy.

Vernier acuity has usually been tested with stimuli of the same contrast polarity (SC). This traditional vernier acuity was compared to that obtained with stimuli of opposite-contrast (OC) in which one target was brighter than the background and the other was darker. For both bar and dot targets vernier acuity with OC stimuli was about half as good as with SC stimuli. There were large individual differences in the size of the disadvantage with OC stimuli, although thresholds remained within the hyperacuity range. There were also individually-differing biases to see a dark vernier stimulus on one or the other side of a bright stimulus. Differences between OC and SC vernier acuities persisted over a wide range of interstimulus spacings, widths, and contrasts. At extremes of these spatial manipulations acuities became similar, but only because SC acuities were degraded to the level of OC acuities. Subjects showed little improvement in OC vernier acuity, even after 50,000 trials. It is concluded that finest judgements of spatial position arise in a level of the visual system at which light and dark stimuli are treated independently.

Suppression theory attributes the singleness of vision during binocular viewing to inconspicuous binocular rivalry. In two experiments, reaction time (RTs) for detection of a small molecular probe were measured while the eyes viewed identical ("fusion") or different (rivalry) stimuli. As expected, distributions of RTs obtained during binocular rivalry showed large positive skew, from trials in which detection was delayed because the probe was superimposed on the suppressed field. Opposite to the prediction of suppression theory, however, the RT distribution during fusion showed far less positive skew, implying that information is available from both eyes during binocular viewing, as held by fusion theory. These findings were confirmed and extended over a large range of probe luminances. During fusion, log mean RTs fell steeply as log probe luminance was increased up to a critical value, then less steeply for further increases. During rivalry, the same steep branch of the RT-luminance function appeared, but shifted as though the probe was about 0.25 log units dimmer. The second branch was also present, but steeper than for fusion, so that RTs for fusion and rivalry were the same at the highest values tested.

Binocular rivalry was induced between two orthogonal square-wave gratings of the same spatial frequency, luminance, contrast, and field size, presented dichoptically. One of the gratings could be instantly replaced by a third grating differing only in orientation. In one experiment subjects were required to respond as soon as an orientation change was noticed, and to withhold response to catch trials (no orientation change). When orientation changes were made to the visible grating, reaction time was found to be a U-shaped function of the magnitude of orientation change. When orientation changes were made to the grating undergoing binocular-rivalry suppression, an overall increase in reaction time was found with the increase being greater for large orientation changes (an asymmetrical U-shaped function). In another experiment subjects were required to detect the direction of a change in orientation in a two-alternative forced-choice procedure. Thresholds were thus obtained for 75% correct performance. It was found that thresholds for orientation changes made to the visible and invisible fields were identical from 20 degrees to 70 degrees orientation change. Outside this range thresholds were higher when orientation changes were made to the field suppressed by binocular rivalry. It is argued that the orientation functions obtained in the two experiments may represent incomplete suppression of either form or transient information during binocular rivalry.

The relationship between patients' characteristics and dentists' perceptions as well as the associations between these dimensions and specific dentist behaviors as perceived by patients are explored. Dentist perceptions of patient sophistication and anxiety were related to several patient characteristics, but perceptions of patient likability were unrelated to patient personal and social characteristics. Perceptions of patient likability were associated with more specific dentist behaviors than were other dentist perceptions noted by patients. The results suggest that dentists' views are influenced primarily by those patient characteristics manifested during treatment. In general, dentists like patients who are dentally sophisticated and not anxious.

Dentists in general practice were surveyed by mail questionnaire to determine the actions they were taking to promote cigarette smoking cessation among their patients. Findings are based on replies from 376 of the 466 dentists in western New York State to whom the questionnaire was sent in 1981. The responses indicate that less than 18 percent of western New York State dentists smoke. The proportion is continuing its gradual decline, and dentists lead the general population in smoking abstention. Sixty-two percent of the dentists in the survey do not permit smoking in their waiting rooms, and 84 percent advise patients not to smoke. There is clear evidence of a relationship between the dentists' own smoking habits and their inclination to promote smoking cessation among patients. As fewer dentists smoke, more will be inclined to foster nonsmoking. Dentists can use a variety of smoking cessation techniques. To carry out a minimal program of antismoking measures, dentists in general practice can serve as nonsmoking role models for their patients, provide information about the health hazards of smoking, give advice, refer patients to cessation programs, recommend cessation measures, and monitor patients' efforts to quit smoking. While smoking cessation measures taken by dentists are not likely to convert more than 1 or 2 percent of patients who smoke per year, in time the dentists' efforts to promote smoking cessation can have an appreciable impact.

Almost 1,000 American dentists attending the 1982 Association annual meeting completed a self-administered questionnaire on sources of stress in dental practice. Most respondents identified dentistry as more stressful than other occupations. However, most believed that other dentists were under more stress than themselves. Dentists use a variety of ways to cope with their stress but a fourth report they do nothing. The stressors particularly noted included falling behind schedule, striving for technical perfection, causing pain or anxiety in patients, canceled or late appointments, and lack of cooperation from patients in the chair. However, all of the 25 listed stressors were endorsed by at least some dentists. Among the stressors lowest in the composite ratings included: isolation from fellow practitioners, competition, monotony, lack of acceptance by patients of the preferred treatment plan, and lack of appreciation. An exploratory factor analysis leads us to hypothesize six sources in dentists' stress: problems of patients' compliance, pain, and anxiety; interpersonal relations; the physical strain of work; economic pressures; third-party constraints; and the strain of perfectionism and seeking ideal results. As the well-being of the dentist and that of the staff and patients are dependent on successful management of occupational strains, this topic deserves more empirical study than it has so far received. We strongly suggest more studies dealing with stresses that occur daily in the immediate environment of office, waiting room, and operatory.

The emergence of transvaginal ultrasound-guided oocyte retrieval provided an opportunity to review and improve the traditional transabdominal ultrasonic approach for follicular tracking in in vitro fertilisation (IVF). This technique requires a full bladder, which may cause extreme discomfort. Hence, to provide both effective and comfortable monitoring, we instituted a study comparing transabdominal and transvaginal ultrasonography, with regard to patient preference and follicular number, size and dominance, in patients undergoing IVF and gamete intrafallopian transfer (GIFT). Commencing usually on day 9 of the treatment cycle, 45 patients were scanned on 55 occasions, initially abdominally (with a full bladder) and subsequently vaginally, using a transvaginal 7.5 MHz sector transducer. Follicular number was identical in 78% of cases, with the majority of the remaining patients showing an extra follicle on vaginal assessment. There were no significant differences in overall or dominant follicular diameters with either technique. Overall, 85% unashamedly preferred the vaginal approach. We believe that tracking follicular development in IVF treatment cycles is efficient and popular using the vaginal sector transducer and accordingly have ceased all assessments using the abdominal probe. Subsequently, 450 follicle scans have been performed with virtually the unanimous approval of our patients.

The study describes the smoking habits of student nurses and determines the correlates of smoking initiation, continuation, and cessation. The sample included 1,163 students attending 10 nursing schools in Buffalo, NY. Data were gathered by means of a self-administered questionnaire. Approximately 30 percent of the students were current smokers, 25 percent were exsmokers, and 45 percent had never smoked. More than half of the smokers (57 percent) expressed the desire to quit, and 81 percent had tried to do so in the past. Major reasons for trying to quit were to protect future health, save money, self-discipline, and pressure from significant others. Most (90 percent) of the students who had tried to quit had attempted to do so on their own and all at once. Knowledge of the health consequences of smoking was not significantly related to smoking behavior. These data suggest the need for health educators to promote personal health practices among their students that are congruent with the goals of the nursing profession of health promotion and disease prevention.

Our sample of 376 dentists in general practice provided a number of useful insights into the problems that dentists experience with their patients. For general problems of patient cooperation, the frequency of occurrence and annoyance to the dentist were related. High on the list in both categories were maintaining poor oral hygiene, missing or being late for appointments, and not paying bills. Not providing an accurate history ranked first in bother to the dentist but appears to occur infrequently. When specific chair problems were considered, an inverse relationship was found between frequency of occurrence and bother to the dentist. Showing fear was the most frequent behavior but ranked lowest in bother. Grabbing the dentist's hand ranked first in bother but last in frequency of occurrence. Some annoying patient behaviors, such as those that devalue, criticize, or question the dentist's performance, are attempts to cope with anxiety. Viewed in this fashion, the incidence of fear-related behaviors may be higher than actually perceived by dentists. Because such behaviors are likely to result in feelings of personal assault on the dentist's part, they are likely to have a deleterious effect on the dentist-patient relationship. Dentists who are able to avoid feeling threatened by patient hostility may be able to successfully resolve the potential conflict to the mutual benefit of both dentist and patient. The actual problems that dentists have with their patients have been neglected and need extensive research. Our study is a first attempt to outline the boundaries of this area. Even these descriptive findings point to crucial elements in dentist-patient relationships. We hope that our findings will lead to further research on the dentist in the dentist-patient equation as well as to practical means of coping with the problems that patients present.