On reductions of some KdV-type systems and their link to the quartic He'non-Heiles Hamiltonian

A few 2+1-dimensional equations belonging to the KP and modified KP hierarchies are shown to be sufficient to provide a unified picture of all the integrable cases of the cubic and quartic H\'enon-Heiles Hamiltonians.Comment: 12 pages, 3 figures, NATO ARW, 15-19 september 2002, Elb

Completeness of the cubic and quartic H\'enon-Heiles Hamiltonians

The quartic H\'enon-Heiles Hamiltonian $H = (P_1^2+P_2^2)/2+(\Omega_1 Q_1^2+\Omega_2 Q_2^2)/2 +C Q_1^4+ B Q_1^2 Q_2^2 + A Q_2^4 +(1/2)(\alpha/Q_1^2+\beta/Q_2^2) - \gamma Q_1$ passes the Painlev\'e test for only four sets of values of the constants. Only one of these, identical to the traveling wave reduction of the Manakov system, has been explicitly integrated (Wojciechowski, 1985), while the three others are not yet integrated in the generic case $(\alpha,\beta,\gamma)\not=(0,0,0)$. We integrate them by building a birational transformation to two fourth order first degree equations in the classification (Cosgrove, 2000) of such polynomial equations which possess the Painlev\'e property. This transformation involves the stationary reduction of various partial differential equations (PDEs). The result is the same as for the three cubic H\'enon-Heiles Hamiltonians, namely, in all four quartic cases, a general solution which is meromorphic and hyperelliptic with genus two. As a consequence, no additional autonomous term can be added to either the cubic or the quartic Hamiltonians without destroying the Painlev\'e integrability (completeness property).Comment: 10 pages, To appear, Theor.Math.Phys. Gallipoli, 34 June--3 July 200

Theory and particle tracking simulations of a resonant radiofrequency deflection cavity in TM110_{110} mode for ultrafast electron microscopy

We present a theoretical description of resonant radiofrequency (RF) deflecting cavities in TM$_{110}$ mode as dynamic optical elements for ultrafast electron microscopy. We first derive the optical transfer matrix of an ideal pillbox cavity and use a Courant-Snyder formalism to calculate the 6D phase space propagation of a Gaussian electron distribution through the cavity. We derive closed, analytic expressions for the increase in transverse emittance and energy spread of the electron distribution. We demonstrate that for the special case of a beam focused in the center of the cavity, the low emittance and low energy spread of a high quality beam can be maintained, which allows high-repetition rate, ultrafast electron microscopy with 100 fs temporal resolution combined with the atomic resolution of a high-end TEM. This is confirmed by charged particle tracking simulations using a realistic cavity geometry, including fringe fields at the cavity entrance and exit apertures

Accent attribution in speakers with Foreign Accent Syndrome

Purpose: The main aim of this experiment was to establish the extent to which the impression of foreignness in speakers with Foreign Accent Syndrome (FAS) is in any way comparable to the impression of foreignness in speakers with a real foreign accent. Method: Three groups of listeners attributed accents to conversational speech samples of 5 FAS speakers which were embedded amongst those of 5 speakers with a real foreign accent and 5 native speaker controls. The listener groups differed in their familiarity with foreign accented speech and speech pathology. Results: The findings indicate that listeners’ perceptual reactions to the three groups of speakers are essentially different at all levels of analysis. The native speaker controls are unequivocally considered as native speakers of Dutch while the speakers with a real foreign accent are very reliably assessed as non-native speakers. The speakers with Foreign Accent Syndrome, however, are in some sense perceived as foreign and in some sense as native by listeners, but not as foreign as speakers with a real foreign accent nor as native as real native speakers. This result may be accounted for in terms of the trigger support model of foreign accent perception. Conclusions: The findings of the experiment is consistent with the idea that the very nature of the foreign accent in different in both groups of speakers, although it cannot be fully excluded that the perceived foreignness in the two groups is one of degree

Construction of Special Solutions for Nonintegrable Systems

The Painleve test is very useful to construct not only the Laurent series solutions of systems of nonlinear ordinary differential equations but also the elliptic and trigonometric ones. The standard methods for constructing the elliptic solutions consist of two independent steps: transformation of a nonlinear polynomial differential equation into a nonlinear algebraic system and a search for solutions of the obtained system. It has been demonstrated by the example of the generalized Henon-Heiles system that the use of the Laurent series solutions of the initial differential equation assists to solve the obtained algebraic system. This procedure has been automatized and generalized on some type of multivalued solutions. To find solutions of the initial differential equation in the form of the Laurent or Puiseux series we use the Painleve test. This test can also assist to solve the inverse problem: to find the form of a polynomial potential, which corresponds to the required type of solutions. We consider the five-dimensional gravitational model with a scalar field to demonstrate this.Comment: LaTeX, 14 pages, the paper has been published in the Journal of Nonlinear Mathematical Physics (http://www.sm.luth.se/math/JNMP/

Observing mother-child interaction in a free-play vs. a structured task context and its relationship with preterm and term born toddlers' psychosocial outcomes

IntroductionHigh quality of mother-child interaction is associated with better psychosocial outcomes in children. However, this association might depend on the context in which mother-child interaction is observed as well as specific child characteristics. In this study, we examine differences in the assessment of mother-child interaction in a free-play and a structured task context. In addition, it will be investigated whether the behaviors per context are differently associated with preterm vs. term born toddlers' psychosocial outcomes.MethodsA total of 201 Dutch mother-child dyads participated in the study, of whom 108 children were moderate to late preterm (MLP) and 93 were born at term. Mother-child interaction was observed in a free-play and a structured task context when the child was 18 months of (corrected) age. Six subscales of mother-child interaction were assessed using the Coding Interactive Behavior scheme: maternal stimulation, maternal warmth, child's negative affect, active mother and child engagement, dyadic synchrony and tense interaction. Psychosocial outcomes were assessed at 24 months of (corrected) age using the Ages and Stages Questionnaire – Social Emotional and the Child Behavior Checklist.ResultsMother-child interaction was reliably assessed (α > .60) in each context, except for tense interaction during free-play (α = .41) and child's negative affect when averaged across contexts (α = 0.55). Compared to the free-play context, during the structured task, more child's negative affect, tense interaction and active mother and child engagement was observed in MLP and term born children, and less dyadic synchrony in MLP children (p's < .01). Only during a structured task and for term born children, active mother and child engagement was related to less social-emotional difficulties, internalizing and externalizing behaviors. Only during free-play and for MLP children, active mother and child engagement was related to less externalizing behaviors. Dyadic synchrony during a structured task was associated with less social-emotional difficulties in MLP and term born children, and dyadic synchrony during free-play was only associated with less social-emotional difficulties in term born children (all p's < .05).DiscussionMost mother-child interactive behaviors can be reliably assessed in both contexts. The structured task context elicited more varied behaviors than the free-play context. With the observations in the structured task context, more associations with children's psychosocial outcomes were found than with the observations in the free-play context. Mother-child interactions characterized by active, engaged and synchronous behaviors were associated with better psychosocial outcomes in toddlers, with some differences observed for MLP vs. term born children and for the free-play vs. the structured task context. Suggestions for future research as well as clinical practice are provided

Is maternal negative affectivity related to psychosocial behavior of preterm and term-born toddlers through mother–child interaction?

Introduction: Children born moderately to late preterm (MLP) are more prone to psychosocial difficulties than their term-born counterparts. Maternal negative affectivity (NA)–a relatively stable personality trait characterized by the tendency to experience negative thoughts, feelings and emotions–has been related to more psychosocial problems in their offspring, and to a lower quality of mother–child interactions. As MLP children seem more sensitive to their early caregiving environment, they might be more affected by maternal NA and interaction style than their term-born peers. The current study investigated whether maternal NA predicted child’s psychosocial outcomes through quality of mother–child interaction, and if these associations differed between MLP and term-born children. Methods: The sample consisted of 108 MLP and 92 term-born children and their mothers. At 18 months corrected age, maternal NA was measured using a self-report questionnaire and mother–child interaction was observed during two structured tasks. Five subscales of mother–child interaction were assessed: negative interaction, reciprocal engagement, emotional support, maternal stimulation and mother-led interaction. At 24 months corrected age, social–emotional difficulties, internalizing, and externalizing problems were assessed using mother-report. Results: For MLP children, maternal NA directly, positively, predicted social–emotional difficulties (b = 0.57) and internalizing problems (b = 0.45), but no mediation effect of mother–child interaction was found. For term-born children, no direct effect but a mediation effect of mother-led interaction was found. Higher levels of maternal NA predicted less mother-led interaction which in turn predicted more problems. Birth status did not moderate any of the relationships, showing that the differences in patterns of effects found within the MLP and term-born group did not reach statistical significance. Discussion: Maternal NA was found to be a risk factor for psychosocial outcomes in toddlers, either directly for MLP children or indirectly through mother-led interaction for term-born children. These findings suggest that the process through which maternal NA affects psychosocial outcomes may be different for MLP and term-born children. However, as the examined moderation effects of birth status did not reach statistical significance, more research using larger sample sizes is needed to study mother–child interaction in greater detail

Gender differences in tumor characteristics, treatment allocation and survival in stage I–III pancreatic cancer:a nationwide study

Introduction: Sex and gender are modulators of health and disease and may have impact on treatment allocation and survival in patients with cancer. In this study, we analyzed the impact of sex and gender on treatment allocation and overall survival in patients with stage I-III pancreatic cancer. Methods: Patients with stage I-III pancreatic cancer diagnosed between 2015 and 2020 were selected from the nationwide Netherlands Cancer Registry. Associations between sex and gender and the probability of receiving surgical and/or systemic treatment were examined with multivariable logistic regression analyses. Overall survival was assessed with log rank test and multivariable Cox proportional hazard analysis. Results: Among 6855 patients, 51.2 % were female. Multivariable logistic regression analyses with adjustment for known confounders (age, performance status, comorbidities, tumor location, tumor stage and previous malignancies) showed that females less often received systemic chemotherapy compared to males (OR 0.799, 95 %CI 0.703–0.909, p &lt; .001). No difference was found in the probability for undergoing surgical resection. Furthermore, females had worse overall survival compared to males (median OS 8.5 and 9.2 months respectively, 95 %CI 8.669–9.731). Conclusion: This nationwide study found that female patients with stage I-III pancreatic cancer significantly less often received systemic treatment and had worse overall survival as compared to males. Disparities in pancreatic cancer care can be decreased by recognizing and resolving potential obstacles or biases in treatment decision-making.</p

Androgens and spermatogenesis: lessons from transgenic mouse models

Transgenic mouse models have contributed considerably to our understanding of the cellular and molecular mechanisms by which androgens control spermatogenesis. Cell-selective ablation of the androgen receptor (AR) in Sertoli cells (SC) results in a complete block in meiosis and unambiguously identifies the SC as the main cellular mediator of the effects of androgens on spermatogenesis. This conclusion is corroborated by similar knockouts in other potential testicular target cells. Mutations resulting in diminished expression of the AR or in alleles with increased length of the CAG repeat mimick specific human forms of disturbed fertility that are not accompanied by defects in male sexual development. Transcriptional profiling studies in mice with cell-selective and general knockouts of the AR, searching for androgen-regulated genes relevant to the control of spermatogenesis, have identified many candidate target genes. However, with the exception of Rhox5, the identified subsets of genes show little overlap. Genes related to tubular restructuring, cell junction dynamics, the cytoskeleton, solute transportation and vitamin A metabolism are prominently present. Further research will be needed to decide which of these genes are physiologically relevant and to identify genes that can be used as diagnostic tools or targets to modulate the effects of androgens in spermatogenesis