Double butterfly spectrum for two interacting particles in the Harper model

We study the effect of interparticle interaction $U$ on the spectrum of the Harper model and show that it leads to a pure-point component arising from the multifractal spectrum of non interacting problem. Our numerical studies allow to understand the global structure of the spectrum. Analytical approach developed permits to understand the origin of localized states in the limit of strong interaction $U$ and fine spectral structure for small $U$.Comment: revtex, 4 pages, 5 figure

Bloch electron in a magnetic field and the Ising model

The spectral determinant det(H-\epsilon I) of the Azbel-Hofstadter Hamiltonian H is related to Onsager's partition function of the 2D Ising model for any value of magnetic flux \Phi=2\pi P/Q through an elementary cell, where P and Q are coprime integers. The band edges of H correspond to the critical temperature of the Ising model; the spectral determinant at these (and other points defined in a certain similar way) is independent of P. A connection of the mean of Lyapunov exponents to the asymptotic (large Q) bandwidth is indicated.Comment: 4 pages, 1 figure, REVTE

Enhanced ionization in small rare gas clusters

A detailed theoretical investigation of rare gas atom clusters under intense short laser pulses reveals that the mechanism of energy absorption is akin to {\it enhanced ionization} first discovered for diatomic molecules. The phenomenon is robust under changes of the atomic element (neon, argon, krypton, xenon), the number of atoms in the cluster (16 to 30 atoms have been studied) and the fluency of the laser pulse. In contrast to molecules it does not dissappear for circular polarization. We develop an analytical model relating the pulse length for maximum ionization to characteristic parameters of the cluster

Health- related quality of life and self-worth in 10-year old children with congenital hypothyroidism diagnosed by neonatal screening

Contains fulltext : 108082.pdf (publisher's version ) (Open Access)ABSTRACT: BACKGROUND: Much is written about cognitive and motor development; less is known about social and emotional consequences of growing up with congenital hypothyroidism (CH).The objectives of the study were: (1) to compare health related quality of life (HRQoL) and self-worth of 10 year old patients with CH with the general population; (2) to explore associations of disease factors, IQ and motor skills with the outcomes. METHODS: Children with CH and their parents completed several questionnaires. Patients were classified to 'severe CH, n = 41' or 'moderate/mild CH, n = 41' based on pre-treatment FT4 concentration.Differences between CH and the general population were tested by analysis of covariance and one sample t-tests (mean scale scores HRQoL and self-worth), chi-square tests and binomial tests (% at risk of impaired HRQoL and self-worth). Linear regression analyses corrected for gender were conducted to explore associations of the outcomes with disease factors, IQ and motor skills. RESULTS: Patients with CH reported lower mean HRQoL on motor, cognitive and social functioning, and on autonomy and positive emotions (p < 0.0001). Patients were also more often at risk for impaired HRQoL and self-worth. No differences were found between the severity groups. Lower IQ was only significant associated with worse cognitive HRQoL. Initial FT4 plasma, age at onset of therapy, initial T4 dose and motor skills were not significantly associated with HRQoL and self-worth. CONCLUSIONS: Negative consequences in terms of HRQoL and self-worth are prevalent in children with CH, independent of disease factors, IQ and motor skills. Physicians should to be attentive to these consequences and provide attention and supportive care

Acceptance conditions in automated negotiation

In every negotiation with a deadline, one of the negotiating parties has to accept an offer to avoid a break off. A break off is usually an undesirable outcome for both parties, therefore it is important that a negotiator employs a proficient mechanism to decide under which conditions to accept. When designing such conditions one is faced with the acceptance dilemma: accepting the current offer may be suboptimal, as better offers may still be presented. On the other hand, accepting too late may prevent an agreement from being reached, resulting in a break off with no gain for either party. Motivated by the challenges of bilateral negotiations between automated agents and by the results and insights of the automated negotiating agents competition (ANAC), we classify and compare state-of-the-art generic acceptance conditions. We focus on decoupled acceptance conditions, i.e. conditions that do not depend on the bidding strategy that is used. We performed extensive experiments to compare the performance of acceptance conditions in combination with a broad range of bidding strategies and negotiation domains. Furthermore we propose new acceptance conditions and we demonstrate that they outperform the other conditions that we study. In particular, it is shown that they outperform the standard acceptance condition of comparing the current offer with the offer the agent is ready to send out. We also provide insight in to why some conditions work better than others and investigate correlations between the properties of the negotiation environment and the efficacy of acceptance condition

Quality of life, developmental milestones, and self-esteem of young adults with congenital hypothyroidism diagnosed by neonatal screening

Contains fulltext : 71281.pdf (publisher's version ) (Closed access)CONTEXT: With advances in the treatment of congenital hypothyroidism (CH), the neuropsychological functioning of CH patients is considerably improved. Although much is written about cognitive and motor development, little is known about emotional and social consequences for patients growing up with CH, diagnosed by neonatal screening. OBJECTIVES: The objectives of the study were to: 1) compare health-related quality of life (HRQoL), developmental milestones also called course of life (CoL), sociodemographical outcomes, and self-esteem of CH patients with the general population; and 2) explore whether severity of CH was related to these outcomes. DESIGN/SETTING/PATIENTS: A total of 69 young adults with CH, born in The Netherlands in 1981-1982, completed the "TNO-AZL Questionnaire for Adult's Health related Quality of Life" questionnaire, the CoL survey (developmental milestones and sociodemographical outcomes), and a self-esteem questionnaire. MAIN OUTCOME MEASURES: HRQoL, CoL, social demographical outcomes, and self-esteem in young adults with CH were determined. RESULTS: CH patients are more often at risk for HRQoL impairment and reported lower HRQoL on several domains (cognitive functioning, P < 0.0001; sleeping, P < 0.004; pain, P < 0.0001; daily activities, P < 0.004; vitality, P < 0.0001; aggressiveness, P < 0.0001; and depressive moods, P < 0.0001) compared with healthy adults. Patients reported a lower self-esteem (P < 0.005) and had a delayed CoL on the domain of social development (P < 0.016). There were no significant within-group differences between the severity groups for HRQoL, CoL, and self-esteem. CONCLUSIONS: Negative consequences in terms of HRQoL, development, and self-esteem are prevalent in young adults with CH. Health care physicians should be attentive to these consequences and provide additional support (emotional and educational guidance) if necessary

The development of anxiety disorders in childhood: an integrative review

We present an integrative review of the development of child anxiety, drawing on a number of strands of research. Family aggregation and genetic studies indicate raised vulnerability to anxiety in offspring of adults with the disorder (e.g. the temperamental style of behavioural inhibition, or information processing biases). Environmental factors are also important; these include adverse life events and exposure to negative information or modelling. Parents are likely to be key, although not unique, sources of such influences, particularly if they are anxious themselves. Some parenting behaviours associated with child anxiety, such as overprotection, may be elicited by child characteristics, especially in the context of parental anxiety, and these may serve to maintain child disorder. Emerging evidence emphasizes the importance of taking the nature of child and parental anxiety into account, of constructing assessments and interventions that are both disorder specific, and of considering bidirectional influences

Strong resonant tunneling, level repulsion and spectral type for one-dimensional adiabatic quasi-periodic Schr\"{o}dinger operators

In this paper, we consider one dimensional adiabatic quasi-periodic Schr\"{o}dinger operators in the regime of strong resonant tunneling. We show the emergence of a level repulsion phenomenon which is seen to be very naturally related to the local spectral type of the operator: the more singular the spectrum, the weaker the repulsion

Ferroelectric and Incipient Ferroelectric Properties of a Novel Sr_(9-x)PbxCe2Ti2O36 (x=0-9) Ceramic System

Sr_(9-x)PbxCe2Ti12O36 system is derived from the perovskite SrTiO3 and its chemical formula can be written as (Sr_(1-y)Pby)0.75Ce0.167TiO3. We investigated dielectric response of Sr_(9-x)PbxCe2Ti12O36 ceramics (x = 0-9) between 100 Hz and 100 THz at temperatures from 10 to 700 K using low- and high-frequency dielectric, microwave (MW), THz and infrared spectroscopy. We revealed that Sr9Ce2Ti12O36 is an incipient ferroelectric with the R-3c trigonal structure whose relative permittivity e' increases from 167 at 300 K and saturates near 240 below 30 K. The subsequent substitution of Sr by Pb enhances e' to several thousands and induces a ferroelectric phase transition to monoclinic Cc phase for x>=3. Its critical temperature Tc linearly depends on the Pb concentration and reaches 550 K for x=9. The phase transition is of displacive type. The soft mode frequency follows the Barrett formula in samples with x=3. The MW dispersion is lacking and quality factor Q is high in samples with low Pb concentration, although the permittivity is very high in some cases. However, due to the lattice softening, the temperature coefficient of the permittivity is rather high. The best MW quality factor was observed for x=1: Q*f=5800 GHz and e'=250. Concluding, the dielectric properties of Sr_(9- x)PbxCe2Ti12O36 are similar to those of Ba_(1-x)SrxTiO3 so that this system can be presumably used as an alternative for MW devices or capacitors.Comment: subm. to Chem. Mate