ALL POSSIBLE MODEL SELECTION IN PROC MIXED – A SAS MACRO APPLICATION

A user-friendly SAS macro application to perform all possible model selection of fixed effects including quadratic and cross products in the presence of random and repeated measures effects using SAS PROC MIXED is available. This macro application will complement the model selection option currently available in the SAS PROC REG for multiple linear regressions and the experimental SAS procedure GLMSELECT that focuses on the standard independently and identically distributed general linear model for univariate responses. Options are also included in this macro to select the best covariance structure associated with the user-specified fully saturated repeated measures model; to graphically explore and to detect statistical significance of user specified linear, quadratic, interaction terms for fixed effects; and to diagnose multicollinearity, via the VIF statistic for each continuous predictors involved in each model selection step. Two model selection criteria, AICC (corrected Akaike Information Criterion) and MDL (minimal description length) are used in all possible model selection and summaries of the best model selection are compared graphically. The differences in the degree of penalty factors associated with the model dimension between AICC and MDL are investigated. Complete mixed model analysis of final model including data exploration, influential diagnostics, and checking for model violations using the experimental ODS GRAPHICS option available in Version 9.13 is also implemented. Instructions for downloading and running this user-friendly macro application are included

Design and Fabrication of sub-THz Steerable Photonic Transmitter 1×4 Array for Short-Distance Wireless Links

In this paper we present the latest results on the design, fabrication and test of stand-alone photonic devices devoted to ultra-high bandwidth wireless access networks operating near the Terahertz (THz) band. We review the sub-THz photonics-based technology devices developed as part of the TERAPOD project, comprising the monolithically integrated Silicon Nitride photonic integrated circuit for phase distribution, the 1×4 array of integrated Uni-Travelling Carrier Photo-Diodes (UTC-PDs) and the radiative design of the high-frequency four element linear patch antenna array based on Benzocyclobutene (BCB) layers. We also report the suitability to assemble all those components in a robust small-form factor hybrid package

Extended scope of nursing practice: a multicentre randomised controlled trial of appropriately trained nurses and pre-registration house officers in pre-operative assessment in elective general surgery

Aim/ Principal Research Question:1) To determine whether pre-operative assessment carried out by an appropriately trained nurse (ATN) is equivalent in quality to that carried out by a pre-registration house officer (PRHO).2) To assess whether pre-assessments carried out by ATNs and PRHOs are equivalent in terms of cost.3) To determine whether assessments carried out by ATNs are acceptable to patients.4) To investigate the quality of communication between senior medical staff and ATNs.Factors of Interest:The extended role of appropriately trained nurses and pre-registration house officers in pre-operative assessment in elective general surgery.Methods:The study design was principally a prospective randomised equivalence trial but was accompanied by additional qualitative assessment of patient and staff perceptions, and an economic evaluation.The intervention consisted of a pre-operative assessment carried out by either an ATN or a PRHO. Of the patients who completed the study with a full evaluation, 926 patients were randomised to the PRHO arm of the trial and 948 to the ATN arm. Three ATNs took part in the study, one from each centre, together with a total of 87 PRHOs.Immediately following the initial assessment of a patient by a PRHO or an ATN, one of a number of clinical research fellows, all specialist registrars in anaesthetics, repeated the assessment and recorded it on a study form, together with a list of investigations required. The clinical research fellow then evaluated the competency of the initial assessor by comparing the quality of their assessment with their own. Any deficiencies in ordering of investigations and referral to other specialities were met in order to maximise patient care.Sample groups:All patients attending at one site for assessment prior to general anaesthetic for elective general, vascular, urological or breast surgery were potentially included in the study. Of 1907 patients who were randomised, 1874 completed the study with a full evaluation.The study was carried out at four NHS hospitals, three of which were teaching hospitals, in three NHS Trusts in Southampton, Sheffield and Doncaster.Outcome measures:Three areas of ATN and PRHO performance were judged separately, history taking, examination and ordering of tests, and each was graded into one of four categories, the most important of which was under-assessment, which would possibly have affected peri-operative management. In the case of ordering of tests, it was possible to have both over- and under-assessed a patient on different tests.Findings:The pre-operative assessments carried out by the ATNs were essentially equivalent to those performed by the PRHOs in terms of under-assessment that might possibly have affected peri-operative management, although there was variation between the ATNs in terms of the quality of history taking. This may be related to the low number of patients seen at one study site.PRHOs ordered significantly more unnecessary tests than the ATNs. The substitution of ATNs for PRHOs was calculated to be cost neutral.The results of the qualitative assessment showed that the use of ATNs for pre-operative assessment was acceptable to patients; however, there was no evidence that communication between senior medical staff and those carrying out pre-operative assessments was improved by their introduction.Conclusions:This study demonstrated no reason to inhibit the development of fully nurse-led pre-operative assessment, provided that the nurses are appropriately trained and maintain sufficient workload to retain skills.Implications for Further Research:Further research is needed in the following areas:1) the extent and type of training needed for nurses undertaking the pre-operative assessment role2) the use, costs and benefits of routine pre-operative testing.<br/

Measurement of residual nucleus cross sections and recoil energies in p + Fe collisions at 300, 500, 750, 1000 and 1500 MeV

The production of residual nuclei in p + Fe collisions has been measured at GSI on the FRS facility by means of the reverse kinematic techniques at 300, 500, 750, 1000 and 1500 MeV/A. The cross-sections larger than 0.01 mb of all isotopes with Z larger than 8 have been obtained. Velocity distributions were also measured. Comparisons to models describing spallation reactions and some empirical formulae often used in astrophysics are presented. These data are directly used to calculate impurety production and DPAs in a thin window as foreseen in spallation sources or accelerator-driven systems

Spallation Residues in the Reaction 56Fe + p at 0.3, 0.5, 0.75, 1.0 and 1.5 A GeV

The spallation residues produced in the bombardment of 56}Fe at 1.5, 1.0, 0.75, 0.5 and 0.3 A GeV on a liquid-hydrogen target have been measured using the reverse kinematics technique and the Fragment Separator at GSI (Darmstadt). This technique has permitted the full identification in charge and mass of all isotopes produced with cross-sections larger than 10^{-2} mb down to Z=8. Their individual production cross-sections and recoil velocities at the five energies are presented. Production cross-sections are compared to previously existing data and to empirical parametric formulas, often used in cosmic-ray astrophysics. The experimental data are also extensively compared to different combinations of intra-nuclear cascade and de-excitation models. It is shown that the yields of the lightest isotopes cannot be accounted for by standard evaporation models. The GEMINI model, which includes an asymmetric fission decay mode, gives an overall good agreement with the data. These experimental data can be directly used for the estimation of composition modifications and damages in materials containing iron in spallation sources. They are also useful for improving high precision cosmic-ray measurements.Comment: Submited to Phys. Rev. C (10/2006

Rapid Suppression of the Spin Gap in Zn-doped CuGeO_3 and SrCu_2O_3

The influence of non-magnetic impurities on the spectrum and dynamical spin structure factor of a model for CuGeO$_3$ is studied. A simple extension to Zn-doped ${\rm Sr Cu_2 O_3}$ is also discussed. Using Exact Diagonalization techniques and intuitive arguments we show that Zn-doping introduces states in the Spin-Peierls gap of CuGeO$_3$. This effect can beunderstood easily in the large dimerization limit where doping by Zn creates ``loose'' S=1/2 spins, which interact with each other through very weak effective antiferromagnetic couplings. When the dimerization is small, a similar effect is observed but now with the free S=1/2 spins being the resulting S=1/2 ground state of severed chains with an odd number of sites. Experimental consequences of these results are discussed. It is interesting to observe that the spin correlations along the chains are enhanced by Zn-doping according to the numerical data presented here. As recent numerical calculations have shown, similar arguments apply to ladders with non-magnetic impurities simply replacing the tendency to dimerization in CuGeO$_3$ by the tendency to form spin-singlets along the rungs in SrCu$_2$O$_3$.Comment: 7 pages, 8 postscript figures, revtex, addition of figure 8 and a section with experimental predictions, submmited to Phys. Rev. B in May 199

The evolution of ultraviolet emission lines from the circumstellar material surrounding SN 1987A

The presence of narrow high-temperature emission lines from nitrogen-rich gas close to SN 1987A has been the principal observational constraint on the evolu- tionary status of the supernova's progenitor. A new analysis of the complete five-year set of low and high resolution IUE ultraviolet spectra of SN 1987A (1987.2--1992.3) provide fluxes for the N V 1240, N IV] 1486, He II 1640, OIII] 1665, NIII] 1751, and CIII] 1908 lines with significantly reduced random and systematic errors and reveals significant short-term fluctuations in the light curves. The N V, N IV] and N III] lines turn on sequentially over 15 to 20 days and show a progression from high to low ionization potential, implying an ioni- zation gradient in the emitting region. The line emission turns on suddenly at 83+/-4 days after the explosion, as defined by N IV]. The N III] line reaches peak luminosity at 399+/-15 days. A ring radius of (6.24+/-0.20)E{17} cm and inclination of 41.0+/-3.9 is derived from these times, assuming a circular ring. The probable role of resonant scattering in the N V light curve introduces systematic errors that leads us to exclude this line from the timing analysis. A new nebular analysis yields improved CNO abundance ratios N/C=6.1+/-1.1 and N/O=1.7+/-0.5, confirming the nitrogen enrichment found in our previous paper. From the late-time behavior of the light curves we find that the emission origi- nates from progressively lower density gas. We estimate the emitting mass near maximum (roughly 400 days) to be roughly 4.7E{-2} solar masses, assuming a filling factor of unity and an electron density of 2.6E4 cm^{-3}. These results are discussed in the context of current models for the emission and hydrodynamics of the ring.Comment: 38 pages, AASTeX v.4.0, 13 Postscript figures; ApJ, in pres

Renormalized couplings and scaling correction amplitudes in the N-vector spin models on the sc and the bcc lattices

For the classical N-vector model, with arbitrary N, we have computed through order \beta^{17} the high temperature expansions of the second field derivative of the susceptibility \chi_4(N,\beta) on the simple cubic and on the body centered cubic lattices. (The N-vector model is also known as the O(N) symmetric classical spin Heisenberg model or, in quantum field theory, as the lattice O(N) nonlinear sigma model.) By analyzing the expansion of \chi_4(N,\beta) on the two lattices, and by carefully allowing for the corrections to scaling, we obtain updated estimates of the critical parameters and more accurate tests of the hyperscaling relation d\nu(N) +\gamma(N) -2\Delta_4(N)=0 for a range of values of the spin dimensionality N, including N=0 [the self-avoiding walk model], N=1 [the Ising spin 1/2 model], N=2 [the XY model], N=3 [the classical Heisenberg model]. Using the recently extended series for the susceptibility and for the second correlation moment, we also compute the dimensionless renormalized four point coupling constants and some universal ratios of scaling correction amplitudes in fair agreement with recent renormalization group estimates.Comment: 23 pages, latex, no figure

Study of the Largest Multiwavelength Campaign of the Microquasar GRS 1915+105

We present the results from a multiwavelength campaign of GRS 1915+105 performed from 2000 April 16 to 25. This is one of the largest coordinated set of observations ever performed for this source, covering the wide energy band in radio (13.3-0.3 cm), near-infrared (J-H-K), X-rays and Gamma-rays (from 1 keV to 10 MeV). During the campaign GRS 1915+105 was predominantly in the "plateau" (or low/hard) state but sometimes showed soft X-ray oscillations: before April 20.3, rapid, quasi-periodic (~= 45 min) flare-dip cycles were observed. The radio flares observed on April 17 shows frequency- dependent peak delay, consistent with an expansion of synchrotron-emitting region starting at the transition from the hard-dip to the soft-flare states in X-rays. On the other hand, infrared flares on April 20 appear to follow (or precede) the beginning of X-ray oscillations with an inconstant time delay of ~= 5-30 min. This implies that the infrared emitting region is located far from the black hole by >~ 10E13 cm, while its size is <~ 10E12 cm constrained from the time variability. We find a good correlation between the quasi-steady flux level in the near-infrared band and in the X-ray band. From this we estimate that the reprocessing of X-rays, probably occurring in the outer parts of the accretion disk, accounts for about 20-30% of the observed K magnitude in the plateau state. The OSSE spectrum in the 0.05-10 MeV band is represented by a single power law with a photon index of 3.1 extending to ~1 MeV with no cutoff. The power-law slope above ~30 keV is found to be very similar between different states in spite of large flux variations in soft X-rays, implying that the electron energy distribution is not affected by the change of the state in the accretion disk.Comment: 31 pages, 11 figures. Accepted for publication in ApJ, vol. 571, 2002. Minor corrections. Figure 2 is revised (numbers on the top axis are corrected). References are update

Genetic analysis of a major international collection of cultivated apple varieties reveals previously unknown historic heteroploid and inbred relationships

Domesticated apple (Malus x domestica Borkh.) is a major global crop and the genetic diversity held within the pool of cultivated varieties is important for the development of future cultivars. The aim of this study was to investigate the diversity held within the domesticated form, through the analysis of a major international germplasm collection of cultivated varieties, the UK National Fruit Collection, consisting of over 2,000 selections of named cultivars and seedling varieties. We utilised Diversity Array Technology (DArT) markers to assess the genetic diversity within the collection. Clustering attempts, using the software STRUCTURE revealed that the accessions formed a complex and historically admixed group for which clear clustering was challenging. Comparison of accessions using the Jaccard similarity coefficient allowed us to identify clonal and duplicate material as well as revealing pairs and groups that appeared more closely related than a standard parent-offspring or full-sibling relations. From further investigation, we were able to propose a number of new pedigrees, which revealed that some historically important cultivars were more closely related than previously documented and that some of them were partially inbred. We were also able to elucidate a number of parent-offspring relationships that had resulted in a number of important polyploid cultivars. This included reuniting polyploid cultivars that in some cases dated as far back as the 18th century, with diploid parents that potentially date back as far as the 13th century