Temporal reflection and refraction in the presence of a zero-nonlinearity wavelength.

We put forth a theoretical model allowing for the analysis of short-pulse interactions at time boundaries in waveguides with arbitrary frequency-dependent nonlinear profiles, in particular those exhibiting a zero-nonlinearity wavelength. Moreover, this is performed within a photon-conserving framework, thus circumventing use of the nonlinear Schrödinger equation in such scenarios, as it may lead to unphysical outcomes. Results indicate that the waveguide zero-nonlinearity wavelength has a great influence on said interactions, specifically by defining spectral bands where either signal total reflection or signal transmission can occur. We believe these findings to be of relevance in the area of all-optical switching schemes based on the interaction of short pulses in nonlinear media.

Master equation approach to propagation in nonlinear fibers.

In this Letter, we revisit the quantum theory of propagation in nonlinear fibers. Unlike previous works, we present an effective propagation equation for the reduced density matrix of the complex envelope of the electric field. This original proposal is shown to be in agreement with the theory of quantum noise in fibers and puts forth a powerful tool for the study of fiber-based quantum devices. To underscore its applicability, we analyze the performance of a heralded single-photon scheme in terms of probabilities, an approach that conveniently lends itself to the optimization of such sources.

Quantum Noise in Fibers with Arbitrary Nonlinear Profiles.

In this Letter we introduce a novel equation addressing the effect of quantum noise in optical fibers with arbitrary frequency-dependent nonlinear profiles. To the best of our knowledge, such an endeavor has not been undertaken before despite the growing relevance of fiber optics in the design of new quantum devices. We show that the stochastic generalized nonlinear Schrödinger equation, derived from a quantum theory of optical fibers, leads to unphysical results such as a negative photon number and the appearance of a dominant anti-Stokes sideband when applied to this kind of waveguides. Starting from a recently introduced master-equation approach to propagation in fibers, we derive a novel stochastic photon-conserving nonlinear Schrödinger equation suitable for modeling arbitrary nonlinear profiles, thus greatly enhancing the study of fiber-based quantum devices.

Modulation instability in waveguides doped with anisotropic nanoparticles.

We exploit the anisotropic plasmonic behavior of gold nanorods (AuNRs) to obtain a waveguide with a nonlinear coefficient dependent on both the frequency and polarization of incident light. The optical properties of the waveguide are described by an extension of the Maxwell Garnett model to nonlinear optics and anisotropic nanoparticles. Then, we perform a study of modulation instability (MI) in this system by resorting to the recently introduced photon-conserving nonlinear Schrödinger equation (pcNLSE), as the pcNLSE allows us to model propagation in nonlinear waveguides of arbitrary sign and frequency dependence of the nonlinear coefficient. Results show that the anisotropy of the nanorods leads to two well-differentiated MI regimes, a feature that may find applications in all-optical devices.

Measuring self-steepening with the photon-conserving nonlinear Schrödinger equation.

We propose an original, simple, and direct method to measure self-steepening (SS) in nonlinear waveguides. Our proposal is based on results derived from the recently introduced photon-conserving nonlinear Schrödinger equation (NLSE) and relies on the time shift experienced by soliton-like pulses due to SS upon propagation. In particular, a direct measurement of this time shift allows for a precise estimation of the SS parameter. Furthermore, we show that such an approach cannot be tackled by resorting to the NLSE. The proposed method is validated through numerical simulations, in excellent agreement with the analytical model, and results are presented for relevant spectral regions in the near infrared, the telecommunication band, and the mid infrared, and for realistic parameters of available laser sources and waveguides. Finally, we demonstrate the robustness of the proposed scheme against deviations expected in real-life experimental conditions, such as pulse shape, pulse peak power, pulsewidth, and/or higher-order linear and nonlinear dispersion.

Modulation instability in waveguides with an arbitrary frequency-dependent nonlinear coefficient.

In this Letter, we present, for the first time, to the best of our knowledge, the modulation instability (MI) gain spectrum of waveguides with an arbitrary frequency-dependent nonlinear coefficient ensuring strict energy and photon-number conservation of the parametric process. This is achieved by starting from a linear stability analysis of the recently introduced photon-conserving nonlinear Schrödinger equation. The derived MI gain is shown to predict some unique features, such as a nonzero gain extending beyond a zero-nonlinearity wavelength and a complex structure of the MI gain spectrum. Analytical results are shown to be in excellent agreement with numerical simulations.

Simple method for estimating the fractional Raman contribution.

We propose a novel and simple method for estimating the fractional Raman contribution, fR, based on an analysis of a full model of modulation instability (MI) in waveguides. An analytical expression relating fR to the MI peak gain beyond the cutoff power is explicitly derived, allowing for an accurate estimation of fR from a single measurement of the Raman gain spectrum.

Molecular survey of trichostrongyle nematodes in a Bison bison herd experiencing clinical parasitism, and effects of avermectin treatment.

North American bison (Bison bison) producers face many challenges, including the potential clinical and economics problems caused by trichostrongyle nematodes within their herds. Little is known about the prevalence, intensity, geographical distribution and clinical significance of these parasites in commercial bison herds, even from regions where bison production has become popular. This study involved a large herd of bison from eastern South Dakota that was experiencing clinical parasitism due to a temporary over-stocking problem. After documenting fecal egg counts (FECs) and trichostrongyle genera present among the 3 main age-categories (i.e. adults, yearlings, calves) of bison during this heavily infected grazing season, the effects of doramectin treatment on the different age groups was also evaluated. This is the first bison study using PCR to identify genera of trichostrongyles in fecal samples. Virtually all 103 bison fecal samples from all 3 age classes were shedding trichostrongyle eggs by the end of the season, and the mean FECs were 34 eggs/g (EPG) among the cows, 125 EPG in the yearlings, and 186 EGP among calves. Based upon this heavily-infected herd, there is evidence that the susceptibility of bison to trichostrongyles is more similar to beef cattle than to sheep. Other parasites such as Moniezia, Nematodirus, Trichuris, and coccidians were also identified in these samples. All but 3 of the 51 samples analyzed with PCR shown at least 1 trichostrongyle genera. Ostertagia was detected in 68.6% of the samples, Cooperia in 80.39%, Haemonchus in at least 73% and Trichostrongylus in 16% of the herd. Most commonly, bison were infected with combinations of Haemonchus/Ostertagia/Cooperia. After treatment with doramectin, the mean FECs dropped by 99.9% for all of the bison age classes.

Uncertainty relation for the optimization of optical-fiber transmission systems simulations.

The mathematical inequality which in quantum mechanics gives rise to the uncertainty principle between two non commuting operators is used to develop a spatial step-size selection algorithm for the Split-Step Fourier Method (SSFM) for solving Generalized Non-Linear Schrödinger Equations (G-NLSEs). Numerical experiments are performed to analyze the efficiency of the method in modeling optical-fiber communications systems, showing its advantages relative to other algorithms.

Suicide and violence associated with panic attacks.

Several studies have indicated that patients with panic attacks have a higher rate of suicide attempts as well as deaths from suicide. Additionally, several investigators have presented case reports of individuals manifesting suicidal and violent behaviors directly and temporally associated with panic attacks. We report on four additional cases and suggest that these findings may explain, in part, the increased rate of suicidal behavior among patients with panic attacks found by some investigators. Furthermore, these case reports offer preliminary evidence that the relationship between violent behavior and the panic state may be clinically significant and deserving of further elucidation.

Assessing positive and negative symptoms in children and adolescents.

OBJECTIVE: The purpose of this study was to test the reliability and validity of a new assessment instrument for positive and negative symptoms in severely disturbed children and adolescents (Kiddie-PANSS). METHOD: The Positive and Negative Syndrome Scale for adult schizophrenia was modified through successive field trials on the basis of developmental characteristics of children and adolescents. The scale was then given to 34 inpatients (19 children, mean age = 9.35 years, and 15 adolescents, mean age = 14.33 years) with DSM-III-R diagnoses of schizophrenia, psychosis not otherwise specified, schizoaffective, affective, conduct, personality, and developmental disorders determined independently by child psychiatrists. All patients with schizophrenia were placed in the schizophrenic group, and all others were placed in a general inpatient group. The Kiddie-PANSS ratings were given by three trained child psychiatrists after a 30-35-minute structured interview. The Achenbach Child Behavior Checklist, the Scale for the Assessment of Positive Symptoms, and the Scale for the Assessment of Negative Symptoms were also administered in order to determine criterion-related association. RESULTS: Intraclass correlation coefficients revealed that all subscales and total psychopathology were reliably assessed among raters. The Kiddie-PANSS and Scale for the Assessment of Positive Symptoms/Scale for the Assessment of Negative Symptoms correlated with one another, indicating criterion-related association. Differences on measures of positive, negative, and general psychopathology, as measured by the Kiddie-PANSS, between the patients with schizophrenia and the general inpatient group were highly significant. CONCLUSIONS: The Kiddie-PANSS shows good interrater reliability and criterion-related validity. In a cohort of inpatient children and adolescents the scale successfully differentiated schizophrenic patients from nonschizophrenic patients.

Oral almotriptan vs. oral sumatriptan in the abortive treatment of migraine: a double-blind, randomized, parallel-group, optimum-dose comparison.

BACKGROUND: Almotriptan malate is a novel, selective serotonin(1B/D) agonist, or triptan, developed for the abortive treatment of migraine. In double-blind, placebo-controlled studies, it has been shown to be effective, well tolerated, and safe. OBJECTIVE: To compare the efficacy, tolerability, and safety of almotriptan with that of the "standard triptan," sumatriptan succinate. The power calculation of the study was based on 24-hour headache recurrence, an efficacy measure in the abortive treatment of migraine, and on the occurrence of adverse events. SUBJECTS AND METHODS: Subjects, aged between18 and 65 years, with migraine with or without aura but otherwise healthy, were randomized to take orally either almotriptan malate, 12.5 mg, or sumatriptan succinate, 50 mg. The medications were provided in identical-looking capsules to ensure blinding and were taken for the treatment of moderate or severe headache. Efficacy was determined in terms of (1) headache relief-a decrease in pain intensity to mild or no pain; (2) headache freedom-a decrease to no pain; (3) use of rescue medications, allowed after 2 hours; and (4) headache recurrence-moderate or severe pain returning within 24 hours after headache relief at 2 hours. Adverse events were collected for 96 hours after treatment and for safety evaluation, vital signs, blood tests, and electrocardiograms were performed at the screening and exit visits. RESULTS: Seventy-five investigators enrolled 1255 subjects of whom 1173 were treated (591 with almotriptan and 582 with sumatriptan). At 2 hours, almotriptan treatment provided headache relief in 58.0% of the subjects and sumatriptan treatment in 57.3%; headache freedom was provided by the medications in 17.9% and 24.6%, respectively (P =.005). Rescue medications were taken by 36.7% of the subjects in the almotriptan-treated group and by 33.2% in the sumatriptan-treated group; headaches returned to moderate or severe intensity in 27.4% and 24.0%, respectively. Treatment-emergent adverse events occurred in 15.2% of the subjects in the almotriptan-treated group and in 19.4% in the sumatriptan-treated group (P =.06); treatment-related adverse events occurred in 9.1% and 15.5% of the subjects, respectively (P =.001), including chest pain, which occurred in 0.3% and 2.2%, respectively (P =.004). CONCLUSIONS: Almotriptan and sumatriptan are similarly effective in the abortive treatment of moderate or severe migraine headache; they are also similarly well tolerated and safe.

Testosterone and aggression in children.

OBJECTIVE: A link between serum testosterone and aggressive behavior, which has been demonstrated in numerous animal studies and suggested in several studies of adult men, has never been investigated in children before the time of puberty. METHOD: We measured serum testosterone, sex hormone binding globulin (SHBG), dehydroepiandrosterone (DHEA), and dehydroepiandrosterone sulfate (DHEAS) in 18 highly aggressive prepubertal boys, ages 4 to 10, hospitalized for violent or unmanageable behavior at a state children's psychiatric facility in New York City (the Bronx). We compared them with a group of age and race matched controls from the same demographic area, screened negative for aggressive behavior problems. All the aggressive subjects met DSM-III-R criteria for conduct disorder and scored higher than the 98th percentile on the aggression subscale of the Child Behavior Checklist (mean T = 80 for the group). RESULTS: There were no significant differences between aggressive and nonaggressive children for T, SHBG, DHEA, DHEAS, or ratios of combinations of these variables. CONCLUSIONS: These findings raise questions about inferences from adult studies that testosterone may play a causal role in the development of human aggression. Testosterone does not appear to be a useful biological marker for aggressivity in early childhood.

Desipramine treatment in panic disorder.

Apart from imipramine (IMI), the efficacy of tricyclic antidepressants in panic disorder (PD) has received surprisingly little investigation. The authors report on a 6 week open trial of desipramine (DMI) preceded by a 10 day placebo lead-in, in 15 patients with PD. By week 6, 80% of the patients were globally rated as much or very much improved on a mean dose of 198 mg. Much of the improvement resulted from a reduction in non-panic attack symptomatology (i.e., psychic, somatic and phobic anxiety). Longer duration of illness, male gender and residual psychic anxiety were associated with poorer response in a subgroup of patients. DMI caused minimal intolerable side effects, suggesting possible compliance advantages in comparison to IMI. Beyond supporting the efficacy of DMI in PD, the results of the study point to a significant medication responsive non-panic illness component and caution against over-relying on panic attacks in assessing both illness severity and treatment response.

Numerical and experimental study of stochastic resistive switching.

In this paper we study the role of noise in the context of resistive switching phenomena by means of experiments and numerical simulations. Experiments are conducted on a manganite sample. We show that the addition of external Gaussian noise to a small amplitude driving signal yields a contrast ratio between low- and high-resistance states, comparable to that obtained by the application of a large amplitude noiseless signal. Furthermore, excellent agreement between numerical simulation and measurement allows us to study resistive switching under varying input conditions and, thus, properly characterize the beneficial role of noise. We believe these results might be of relevance in the area of memory devices where the large scale of electronic integration renders the presence of noise unavoidable.

Overwintering strategies of a population of anthelmintic-resistant Haemonchus contortus within a sheep flock from the United States Northern Great Plains.

Haemonchus contortus infections have been increasingly reported in ungulates from cold climates even though past studies have shown that the free-living juveniles from this species survive poorly under freezing conditions. Overwintering strategies of H. contortus have not been documented in the Unites States Northern Great Plains. A PCR survey identified H. contortus as vastly predominant trichostrongyle species present (in addition to occasional detections of Teladorsagia sp.) in a closed farm flock of sheep from Brookings County, SD. Benzimidazole (BZ) and avermectin (AV) anthelmintics had been used intensely for many years on this flock. During the autumn season, three fecal egg count reduction tests (doramectin, albendazole, and moxidectin) were performed over a 4 year span to assess drug effectiveness within the flock. Significant drug resistance was found in Haemonchus adults with doramectin (69% efficacy), marginal resistance was found with albendazole (90% efficacy) and no resistance was found in moxidectin (100% efficacy). The following spring, pre-lambing and post-lambing fecals were obtained from albendazole and moxidectin treatment years to assess the resistance of the tissue-dwelling fourth-stage juveniles (J4s) at those times. Albendazole treated pre-lambing fecals averaged only 4 EPG and treated post-lambing fecals increased to 454 EPG, indicating that many of the J4s were not killed during the autumn treatment. Moxidectin pre-lambing fecals averaged only 1 EPG, and post-lambing fecals only increased to 6 EPG in the treated moxidectin population and 1422 EPG in the untreated moxidectin population. In addition to evaluating the ability of H. contortus to overwinter as drug resistant tissue-dwelling J4s, this study also evaluated the overwintering ability of pasture-dwelling, free-living third-stage juveniles at this farm. In the summers of 2010 and 2011, naïve tracer lambs were placed on a H. contortus contaminated pasture for 3 weeks to assess J3 winter survival. In 2010, tracer lambs only averaged 7 EPG whereas drylotted control lambs averaged 2 EPG; in 2011, tracer lambs averaged 2 EPG while the control lambs averaged 1 EPG. These results suggest that at this northern plains farm, yearly transmission of H. contortus is predominately through drug-resistant J4s. This is consistent with other cold-climate, overwintering studies involving H. contortus from Europe.

Correlates of violence risk in hospitalized adolescents.

Forty adolescent inpatients with histories of frequent interpersonal violent behavior were compared with 36 hospitalized adolescents without histories of overt violence using self-report questionnaires that measured violence risk, depression, impulsivity, and suicide risk. The two groups did not differ in terms of their demographic characteristics, but the violent patients had a higher prevalence of substance abuse and borderline personality disorder diagnoses. Violent adolescents were more impulsive and at higher suicide risk than nonviolent adolescents. In addition, violent adolescents had more positive histories of suicide attempts and had significantly higher family histories of attempted and completed suicide. In the total sample of adolescents, violence risk was significantly correlated with impulsivity and suicide risk, but not with depression.