In transition between child and adult services for young people with Attention Deficit Hyperactivity Disorder (ADHD); the need for transition and the use and usefulness of the National Institute of Health and Care Excellence (NICE) guidelines

This thesis focussed on the transition between child and adult services for young people with Attention Deficit Hyperactivity Disorder (ADHD). It aimed to estimate the incidence of transition, and identify guidelines and protocols for transition and how these are implemented. It also considers the influence of the National Institute of Health and Care Excellence (NICE) guidelines within current health service provision. A multi-method approach was used. A systematic review of existing guidelines for ADHD transition was conducted, providing an overview of current literature. A surveillance study was carried out to estimate the incidence of transition, and to identify whether clinicians adhere to the elements of optimal transition. Clinicians from the surveillance study were invited to participate in a qualitative interview, to gain further insight into their perspectives of the NICE guidelines and how these are used. Finally, the NICE guidelines are considered in a legal context and the question of whether the law can play a part in the transition of young people with ADHD is discussed. In 2016, 315 young people in the British Isles required a transition to an adult service, but only 22% of them completed the transition and were seen in the adult service. An estimated incidence rate of transition was calculated between 202.9 and 511.2 per 100,000 population aged 17-19 per year. The estimated rate of successful transition ranged between 38.5 and 96.9 per 100,000 population aged 17-19 per year. The only available guidelines for transition are the NICE guidelines, and any locally produced protocols are based on what NICE recommend. Interviews with clinicians (n=38) indicated that information transfer occurs between services, but joint working and continuity of care is often not evident, despite the surveillance study demonstrating that a period of joint working is a strong predictor of successful transition. Full implementation of the NICE guidelines could enhance the transition process and have a positive impact on the wellbeing of the young person. However, NICE guidelines are not mandatory, and adherence is poor. In summary, the findings of this thesis highlight the substantial need for transition in ADHD. Current practice does not closely follow the NICE guidelines. Considering the long term implications of poorly managed ADHD and transition for young people and society, it raises questions about the purpose of NICE guidelines if there is a lack of adherence, and clinicians do not consider them a priority

On the Spatial Correlations of Lyman Break Galaxies

Motivated by the observed discrepancy between the strong spatial correlations of Lyman break galaxies (LBGs) and their velocity dispersions, we consider a theoretical model in which these starbursting galaxies are associated with dark matter halos that experience appreciable infall of material. We show using numerical simulation that selecting halos that substantially increase in mass within a fixed time interval introduces a ``temporal bias'' which boosts their clustering above that of the underlying population. If time intervals consistent with the observed LBGs star formation rates of 50 solar masses per year are chosen, then spatial correlations are enhanced by up to a factor of two. These values roughly correspond to the geometrical bias of objects three times as massive. Thus, it is clear that temporal biasing must be taken into account when interpreting the properties of Lyman break galaxies.Comment: 5 Pages, 2 Figures, Accepted for Publication in ApJ Letter

Confronting cold dark matter cosmologies with strong clustering of Lyman break galaxies at z∼3z\sim3

We perform a detailed analysis of the statistical significance of a concentration of Lyman break galaxies at $z \sim 3$ recently discovered by Steidel et al. (1997), using a series of N-body simulations with $N=256^3$ particles in a (100\himpc)^3 comoving box. While the observed number density of Lyman break galaxies at $z\sim3$ implies that they correspond to systems with dark matter halos of \simlt 10^{12}M_\odot, the resulting clustering of such objects on average is not strong enough to be reconciled with the concentration if it is fairly common; we predict one similar concentration approximately per ($6\sim 10$) fields in three representative cold dark matter models. Considering the current observational uncertainty of the frequency of such clustering at $z\sim3$, it would be premature to rule out the models, but the future spectroscopic surveys in a dozen fields could definitely challenge all the existing cosmological models a posteriori fitted to the $z=0$ universe.Comment: the final version which matchs that published in ApJ Letters (Feb 1998); compared with the previous versions, the predictions for the SCDM model are slightly changed; Latex, 11 pages, including 3 ps figure

Some Fixed Point Results of Ciric-Type Contraction Mappings on Ordered G-Partial Metric Spaces

We introduce the concept of generalized quasi-contraction mappings in G-partial metric spaces and prove some fixed point results in ordered G-partial metric spaces. The results generalize and extend some recent results in literature

On the Equivalence of Stochastic Fixed Point Iterations for Generalized Contractive-Like Operators

We present the equivalence of some stochastic fixed point iterative algorithms by proving the equivalence between the convergence of random implicit Jungck-Kirk-multistep, random implicit Jungck-Kirk-Noor, random implicit Jungck-Kirk-Ishikawa, and random implicit Jungck-Kirk-Mann iterative algorithms for generalized φ-contractive-like random operators defined on separable Banach spaces

Anisotropic Galactic Outflows and Enrichment of the Intergalactic Medium. I: Monte Carlo Simulations

We have developed an analytical model to describe the evolution of anisotropic galactic outflows. With it, we investigate the impact of varying opening angle on galaxy formation and the evolution of the IGM. We have implemented this model in a Monte Carlo algorithm to simulate galaxy formation and outflows in a cosmological context. Using this algorithm, we have simulated the evolution of a comoving volume of size [12h^(-1)Mpc]^3 in the LCDM universe. Starting from a Gaussian density field at redshift z=24, we follow the formation of ~20,000 galaxies, and simulate the galactic outflows produced by these galaxies. When these outflows collide with density peaks, ram pressure stripping of the gas inside the peak may result. This occurs in around half the cases and prevents the formation of galaxies. Anisotropic outflows follow the path of least resistance, and thus travel preferentially into low-density regions, away from cosmological structures (filaments and pancakes) where galaxies form. As a result, the number of collisions is reduced, leading to the formation of a larger number of galaxies. Anisotropic outflows can significantly enrich low-density systems with metals. Conversely, the cross-pollution in metals of objects located in a common cosmological structure, like a filament, is significantly reduced. Highly anisotropic outflows can travel across cosmological voids and deposit metals in other, unrelated cosmological structures.Comment: 32 pages, 9 figures (2 color). Revised version accepted in Ap

Toward an Improved Analytical Description of Lagrangian Bias

We carry out a detailed numerical investigation of the spatial correlation function of the initial positions of cosmological dark matter halos. In this Lagrangian coordinate system, which is especially useful for analytic studies of cosmological feedback, we are able to construct cross-correlation functions of objects with varying masses and formation redshifts and compare them with a variety of analytical approaches. For the case in which both formation redshifts are equal, we find good agreement between our numerical results and the bivariate model of Scannapieco & Barkana (2002; SB02) at all masses, redshifts, and separations, while the model of Porciani et al. (1998) does well for all parameters except for objects with different masses at small separations. We find that the standard mapping between Lagrangian and Eulerian bias performs well for rare objects at all separations, but fails if the objects are highly-nonlinear (low-sigma) peaks. In the Lagrangian case in which the formation redshifts differ, the SB02 model does well for all separations and combinations of masses, apart from a discrepancy at small separations in situations in which the smaller object is formed earlier and the difference between redshifts or masses is large. As this same limitation arises in the standard approach to the single-point progenitor distribution developed by Lacey & Cole (1993), we conclude that a more complete understanding of the progenitor distribution is the most important outstanding issue in the analytic modeling of Lagrangian bias.Comment: 22 pages, 8 figures, ApJ, in pres

Hubble Space Telescope weak lensing study of the z=0.83 cluster MS 1054-03

We have measured the weak gravitational lensing signal of MS 1054-03, a rich and X-ray luminous cluster of galaxies at a redshift of z=0.83, using a two-colour mosaic of deep WFPC2 images. The small corrections for the size of the PSF and the high number density of background galaxies obtained in these observations result in an accurate and well calibrated measurement of the lensing induced distortion. The strength of the lensing signal depends on the redshift distribution of the background galaxies. We used photometric redshift distributions from the Northern and Southern Hubble Deep Fields to relate the lensing signal to the mass. The predicted variations of the signal as a function of apparent source magnitude and colour agrees well with the observed lensing signal. We determine a mass of (1.2+-0.2)x10^15 Msun within an aperture of radius 1 Mpc. Under the assumption of an isothermal mass distribution, the corresponding velocity dispersion is 1311^{+83}_{-89} km/s. For the mass-to-light ratio we find 269+-37 Msun/Lsun. The errors in the mass and mass-to-light ratio include the contribution from the random intrinsic ellipticities of the source galaxies, but not the (systematic) error due to the uncertainty in the redshift distribution. However, the estimates for the mass and mass-to-light ratio of MS 1054-03 agree well with other estimators, suggesting that the mass calibration works well. The reconstruction of the projected mass surface density shows a complex mass distribution, consistent with the light distribution. The results indicate that MS 1054-03 is a young system. The timescale for relaxation is estimated to be at least 1 Gyr. Averaging the tangential shear around the cluster galaxies, we find that the velocity dispersion of an Lstar galaxy is 203+-33 km/s.Comment: 21 pages, Latex, with 27 figures (3 figures bitmapped), ApJ, in press. Version (with non-bitmapped figures) available at http://www.astro.rug.nl/~hoekstra/papers.htm

The impact of active stakeholder involvement on recruitment, retention and engagement of schools, children and their families in the cluster randomised controlled trial of the Healthy Lifestyles Programme (HeLP): a school-based intervention to prevent obesity

This is the final version of the article. Available from BioMed Central via the DOI in this record.BACKGROUND: Recruitment and retention of participants is crucial for statistical power and internal and external validity and participant engagement is essential for behaviour change. However, many school-based interventions focus on programme content rather than the building of supportive relationships with all participants and tend to employ specific standalone strategies, such as incentives, to improve retention. We believe that actively involving stakeholders in both intervention and trial design improves recruitment and retention and increases the chances of creating an effective intervention. METHODS: The Healthy Lifestyles Programme, HeLP (an obesity prevention programme for children 9-10 years old) was developed using intervention mapping and involved extensive stakeholder involvement in both the design of the trial and the intervention to ensure that: (i) delivery methods were suitably engaging, (ii) deliverers had the necessary skills and qualities to build relationships and (iii) the intervention dovetailed with the National Curriculum. HeLP was a year-long intervention consisting of 4 multi-component phases using a range of delivery methods. We recruited 1324 children from 32 schools from the South West of England to a cluster-randomised controlled trial to determine the effectiveness of HeLP in preventing obesity. The primary outcome was change in body mass index standard deviation score (BMI SDS) at 24 months post randomisation. Secondary outcomes included additional anthropometric and behavioural (physical activity and diet) measures at 18 and 24 months. RESULTS: Anthropometric and behavioural measures were taken in 99%, 96% and 94% of children at baseline, 18 and 24 months, respectively, with no differential follow up between the control and intervention groups at each time point. All children participated in the programme and 92% of children and 77% of parents across the socio-economic spectrum were considered to have actively engaged with HeLP. CONCLUSIONS: We attribute our excellent retention and engagement results to the high level of stakeholder involvement in both trial and intervention design, the building of relationships using appropriate personnel and creative delivery methods that are accessible to children and their families across the social spectrum. TRIAL REGISTRATION: International Standard Randomised Controlled Trials Register, ISRCTN15811706 . Registered on 1 May 2012.The UK National Institute for Health Research (NIHR) Public Health Research Programme (10/3010/01) funded all research activities for the HeLP RCT. The costs of the intervention were funded by the Peninsula College of Medicine and Dentistry

Physical Bias of Galaxies From Large-Scale Hydrodynamic Simulations

We analyze a new large-scale ($100h^{-1}$Mpc) numerical hydrodynamic simulation of the popular $\Lambda$CDM cosmological model, including in our treatment dark matter, gas and star-formation, on the basis of standard physical processes. The method, applied with a numerical resolution of $<200h^{-1}$kpc (which is still quite coarse for following individual galaxies, especially in dense regions), attempts to estimate where and when galaxies form. We then compare the smoothed galaxy distribution with the smoothed mass distribution to determine the "bias" defined as $b\equiv (\delta M/M)_{gal}/(\delta M/M)_{total}$ on scales large compared with the code numerical resolution (on the basis of resolution tests given in the appendix of this paper). We find that (holding all variables constant except the quoted one) bias increases with decreasing scale, with increasing galactic age or metallicity and with increasing redshift of observations. At the $8h^{-1}$Mpc fiducial comoving scale bias (for bright regions) is 1.35 at $z=0$ reaching to 3.6 at $z=3$, both numbers being consistent with extant observations. We also find that $(10-20)h^{-1}$Mpc voids in the distribution of luminous objects are as observed (i.e., observed voids are not an argument against CDM-like models) and finally that the younger systems should show a colder Hubble flow than do the early type galaxies (a testable proposition). Surprisingly, little evolution is found in the amplitude of the smoothed galaxy-galaxy correlation function (as a function of {\it comoving} separation). Testing this prediction vs observations will allow a comparison between this work and that of Kauffmann et al which is based on a different physical modelingmethod.Comment: in press, ApJ, 26 latex pages plus 7 fig