Linear and nonlinear parity-time-symmetric oligomers: a dynamical systems analysis.

In the present work, we focus on the cases of two-site (dimer) and three-site (trimer) configurations, i.e. oligomers, respecting the parity-time (PT) symmetry, i.e. with a spatially odd gain-loss profile. We examine different types of solutions of such configurations with linear and nonlinear gain/loss profiles. Solutions beyond the linear PT-symmetry critical point as well as solutions with asymmetric linearization eigenvalues are found in both the nonlinear dimer and trimer. The latter feature is absent in linear PT-symmetric trimers, while both of them are absent in linear PT-symmetric dimers. Furthermore, nonlinear gain/loss terms enable the existence of both symmetric and asymmetric solution profiles (and of bifurcations between them), while only symmetric solutions are present in the linear PT-symmetric dimers and trimers. The linear stability analysis around the obtained solutions is discussed and their dynamical evolution is explored by means of direct numerical simulations. Finally, a brief discussion is also given of recent progress in the context of PT-symmetric quadrimers.

Solitary waves in discrete media with four-wave mixing.

In this paper, we examine in detail the principal branches of solutions that arise in vector discrete models with nonlinear intercomponent coupling and four wave mixing. The relevant four branches of solutions consist of two single mode branches (transverse electric and transverse magnetic) and two mixed mode branches, involving both components (linearly polarized and elliptically polarized). These solutions are obtained explicitly and their stability is analyzed completely in the anticontinuum limit (where the nodes of the lattice are uncoupled), illustrating the supercritical pitchfork nature of the bifurcations that give rise to the latter two, respectively, from the former two. Then the branches are continued for finite coupling constructing a full two-parameter numerical bifurcation diagram of their existence. Relevant stability ranges and instability regimes are highlighted and, whenever unstable, the solutions are dynamically evolved through direct computations to monitor the development of the corresponding instabilities. Direct connections to the earlier experimental work of Meier [Phys. Rev. Lett., 91, 143907 (2003)] that motivated the present work are given.

Binge eating disorder: its further validation in a multisite study.

Binge eating disorder (BED) is a new eating disorder that describes the eating disturbance of a large number of individuals who suffer from recurrent binge eating but who do not regularly engage in the compensatory behaviors to avoid weight gain seen in bulimia nervosa. This multisite study of BED involved 1,785 subjects drawn from 18 weight control programs, 942 subjects from five nonpatient community samples, and 75 patients with bulimia nervosa. Approximately 29% of subjects in weight control programs met the criteria for BED. In the nonpatient community samples BED was more common than purging bulimia nervosa. The validity of BED was supported by its strong association with (1) impairment in work and social functioning, (2) overconcern with body/shape and weight, (3) general psychopathology, (4) significant amount of time in adult life on diets, (5) a history of depression, alcohol/drug abuse, and treatment for emotional problems.

Disturbed body image in patients with eating disorders.

OBJECTIVE: The authors attempt to answer the question of whether patients with eating disorders experience more distortions in body image than do individuals without eating disorders. METHOD: The study group was composed of 214 women out of 230 patients consecutively admitted to an inpatient eating disorders program. Twelve men and four patients with atypical eating disorders were excluded from study. The 214 patients were divided into three groups: 87 with anorexia nervosa alone, 72 with anorexia and bulimia nervosa, and 55 with bulimia nervosa alone. The comparison group was composed of 61 women drawn from 125 consecutive participants in a survey of university students. Fifty-six men were dropped from the comparison group, along with eight women who fulfilled diagnostic criteria for eating disorders. Each subject used a three-dimensional measure to rate her body size and stated her desired body size at seven points: left biceps, left calf, left thigh, waist, abdomen, hips, and bust. The subjects' measurements at each of these points were taken. Distortion in body image was calculated as the subject's perceived body size divided by her actual body size. All subjects were also given a battery of tests of intelligence, skill, and memory. RESULTS: All three patient groups differed significantly from the comparison group in distortions in body image. Most but not all patients with eating disorders had distortions in their body image. CONCLUSIONS: If replicated, these findings would suggest that the diagnostic criteria regarding disturbance of body image for both anorexia and bulimia need to be revised.

Hypnotizability of psychiatric inpatients according to two different scales.

Data on the hypnotizability of 113 psychiatric inpatients and 58 normal control subjects were compared. The patients' mean score on the Hypnotic Induction Profile was significantly lower than that of the control subjects, but on the Stanford Hypnotic Susceptibility Scale: Form C, these patients and control subjects did not differ significantly. On both scales rank-ordered scores of different diagnostic groups of the patients supported the theory that hypnotizability varies according to type of psychopathology. Some results, such as the hypnotizability of the schizophrenic patients, depended on which scale was used. This finding may explain the conflicting literature on the hypnotic potential of schizophrenic patients.

Treatment of bulimia with bupropion: a multicenter controlled trial.

In a placebo-controlled, double-blind study of the unique antidepressant agent bupropion in the treatment of nondepressed subjects with bulimia (bupropion group, N = 55; placebo group, N = 26), we found the drug significantly superior to placebo in reducing episodes of binge eating and purging. In general, side effects with bupropion were minimal. However, four subjects experienced grand mal seizures during treatment with bupropion, a frequency of seizures far higher than observed in previous studies with this drug. Pending a satisfactory explanation for the occurrence of these seizures, we recommend that bupropion not be administered alone to bulimic patients.

Comparing bilateral to unilateral electroconvulsive therapy in a randomized study with EEG monitoring.

In a double-blind study, 48 DSM-III depressed patients were randomly assigned to either the bilateral or nondominant unilateral electroconvulsive therapy (ECT) group. Seizure length was monitored by electroencephalography (EEG). When seizures were less than 25 s, ECT was immediately readministered. When length of seizure and pretreatment depression scores were controlled between the two groups, there were no differences in treatment effectiveness, as measured by the Hamilton Rating Scale for Depression and the Beck Depression Inventory, or in the number of treatments required. This was true after five ECT treatments as well as after completing all ECT treatments. Thus, when ECT is monitored via EEG to assure the presence of an adequate seizure, bilateral and nondominant unilateral placement yield equivalent responses. If ECT had not been readministered immediately following a missed seizure, unilateral patients would have had significantly more missed seizures. Significant difficulties in both short- and long-term memory were found 24 hours after the fifth ECT in bilateral but not in nondominant unilateral patients. No apparent memory loss could be documented in nondominant unilateral ECT.

Hypnotizability in patients with anorexia nervosa and bulimia.

Hypnotizability was assessed with the use of three standardized hypnosis scales in 86 patients with eating disorders. All diagnoses were made according to DSM-III criteria. Sixty-five patients had anorexia nervosa and 21 had bulimia. The anorectic patients were divided into subgroups of 19 abstainers and 46 vomiters and purgers. Bulimic patients were highly hypnotizable, significantly more so than the patients with anorexia nervosa and age-matched populations. There was also a trend for the purging subgroup of anorectics to have higher hypnotic capacity than abstaining anorectics.

Dexamethasone in electroconvulsive therapy: efficacy for depression and post-ECT amnesia.

Dexamethasone, compared to placebo in a double-blind study, failed to prevent the memory deficiency that typically accompanies electroconvulsive therapy (ECT) (n = 48 patients treated for DSM-III diagnosed major depressive disorder). Rather, the administration of the drug was associated with attention (p less than 0.02) and short-term memory (p less than 0.0003) difficulties in both bilateral and unilateral ECT patients. Bilateral ECT plus dexamethasone patients had significantly less improvement (p less than 0.05) in their depression (measured by the Hamilton Depression Scale) compared to bilateral ECT plus placebo patients. These depression differences were not seen among unilateral ECT patients.

Random number generation, psychopathology and therapeutic change.

In two studies, 145 psychiatric inpatients were each asked to say 100 numbers in random order, using the numbers 1 through 10. Compared with normative data, patients with personality disorders and neuroses were not impaired on the random number generation (RNG) task and patients with chronic alcoholism and primary affective disorder, depression, were significantly imparied, but not as much as those with schizophrenia and organic brain syndrome. The relationship between RNG performance and psychiatric diagnosis may reflect severity of disturbed cognitive functioning. The Randomization Index was sensitive to changes in symptoms during hospitalization. The RNG task provides a brief objective measure of those components of attention, cognitive capacity, and short-term memory that are affected by severity of psychopathology.

Psychosocial risk factors for lung cancer.

The existence of psychosocial risk factors for the development of malignancy has been postulated by many investigators. This study investigated selected psychosocial factors as predictors of malignancy. 110 male patients with undiagnosed subacute or chronic pulmonary x-ray lesions participated in a semistructured interview. Ratings were made of 5 subscales: 1) childhood instability, 2) job stability, 3) marriage stability, 4) lack of plans for the future, and 5) recent significant loss. The composite scale correctly predicted the diagnosis of 53 (80%) of the 66 patients with benign disease and 27 (61%) of the 44 with lung cancer. The scale was at least as important as smoking history in predicting diagnoses. Thus, significant psychosocial risk factors for the development of malignant disease might well be incorporated in selecting high-risk individuals for cytological or other screening for lung cancer.