Viewpoint consistency in Z and LOTOS: A case study

Specification by viewpoints is advocated as a suitable method of specifying complex systems. Each viewpoint describes the envisaged system from a particular perspective, using concepts and specification languages best suited for that perspective. Inherent in any viewpoint approach is the need to check or manage the consistency of viewpoints and to show that the different viewpoints do not impose contradictory requirements. In previous work we have described a range of techniques for consistency checking, refinement, and translation between viewpoint specifications, in particular for the languages LOTOS and Z. These two languages are advocated in a particular viewpoint model, viz. that of the Open Distributed Processing (ODP) reference model. In this paper we present a case study which demonstrates how all these techniques can be combined in order to show consistency between a viewpoint specified in LOTOS and one specified in Z. Keywords: Viewpoints; Consistency; Z; LOTOS; ODP

In-Shoe Pressure Distribution During Ergometer Rowing In Novice And Experienced Rowers

Distribution of foot pressure during rowing has been minimally investigated. Foot pressure distribution is most likely altered with experience ca using an increase in stability and thus efficiency duirng the rowing stroke. This study evaluated in-shoe pressure distribution differences between novice and experienced collegiate rowers during rowing on the Concept II ergometer. In shoe pressure was measured in ten subjects, five novice and five experienced, while rowing at a stroke rate of 32-34 strokes per minute. The subjects wore the same model shoe with a Tekscan in-shoe pressure measurement system placed inside each shoe, only the dominant foot was studied. Data were sampled at a rate of 100 Hz. The following variables at the shoe-foot interface were investigated during the drive and the recovery of the stroke: peak forefoot pressure, peak rearfoot pressure, and displacement of the mediolateral and longitudinal center of pressure (COP). Peak pressures were investigated to discover how the pressure is distributed during the stroke. Comparison of the COP was used to indicate the stabililty of the foot during the drive phase. The experienced rowers had a high proportion of the total in-shoe pressure in the forefoot during the drive. Generally there was less pressure exerted on the recovery phase in the experienced subjects. These subjects also had a less variable mediolateral COP and an increase in the longitudinal COP plot. To apply force correctly during the drive it seems to be necessary to place a high proportion of the pressure in the forefoot. The trend toward decreased pressure on the recovery in the experienced rowers may reflect an increased efficiency due to experience. The decrease in the mediolateral COP deviation would appear to be related to increased stability. The longitudinal COP plot showed that with experience the plantar surface in contact with the shoe during the drive increases

Defoliation frequency and season affected radiation use efficiency and dry matter partitioning to roots of lucerne (Medicago sativa L.) crops

Radiation use efficiency (RUE), and subsequent partitioning between shoots and roots were investigated for ‘Grasslands Kaituna’ lucerne crops grown in the cool temperate climate of Canterbury, New Zealand. Crops were grazed by sheep every 28 or 42 days and yielded 12 and 23 t DM/ha.year, respectively. The RUE for above ground shoots (RUEshoot) was 1.7-2.0 g DM/MJ of intercepted photosynthetically active radiation (PARᵢ) in spring but decreased systematically to ≤1.0 g DM/MJ PARᵢ in autumn. The RUE for total biomass, (RUEtotal) ranged from 1.3 to 3.1 g DM/MJ PARᵢ in response to air temperature and defoliation treatment. The lowest RUEtotal in mid summer for the treatment defoliated every 28 days was related to a 20% decline in the leaf photosynthetic capacity measured at 1000 μmol photons/m2.s (Pn1000) and at saturating light (Pmax). In turn, the reduction in Pn1000 was related to differences in specific leaf nitrogen (SLN), through changes in specific leaf weight (SLW) rather than the leaf N concentration of 4 to 6% DM. The fractional partitioning of DM to roots (proot) increased from near zero in winter/earlyspring to >0.45 in autumn, which explained the observed seasonality of RUEshoot. For the treatment defoliated each 42 days, proot increased linearly from ~0.05 to >0.45 as Pp increased from 10.5 to 16.5 h. In decreasing photoperiods proot averaged 0.45. There was a linear increase (R²=0.52) in proot with Tsoil/Tair but only in the treatment defoliated each 42 days. Agronomic treatments that result in sub optimal N reserves post grazing can be expected to produce conservative canopy characteristics but reduced photosynthetic capacity of the first 5 main stem leaves. Beyond this development stage, canopy expansion may be reduced with more conservative leaf N

Unitarization of Gluon Exchange Amplitudes and Rapidity Gaps at the Tevatron

Rapidity gaps between two hard jets at the Tevatron have been interpreted as being due to the exchange of two gluons which are in an overall color-singlet state. We show that this simple picture involves unitarity violating amplitudes. Unitarizing the gluon exchange amplitude leads to qualitatively different predictions for the fraction of $t$-channel color singlet exchange events in forward $qq$, $qg$ or $gg$ scattering, which better fit Tevatron data.Comment: 21 pages, Revtex, 7 postscript figures included via epsf.sty. Compressed postscript file of complete paper also available at http://pheno.physics.wisc.edu/pub/preprints/1998/madph-98-1024.ps.Z or at ftp://pheno.physics.wisc.edu/pub/preprints/1998/madph-98-1024.ps.

Real null coframes in general relativity and GPS type coordinates

Based on work of Derrick, Coll, and Morales, we define a `symmetric' null coframe with {\it four real null covectors}. We show that this coframe is closely related to the GPS type coordinates recently introduced by Rovelli.Comment: Latex script, 9 pages, 4 figures; references added to work of Derrick, Coll, and Morales, 1 new figur

The Wilson renormalization group for low x physics: towards the high density regime

We continue the study of the effective action for low $x$ physics based on a Wilson renormalization group approach. We express the full nonlinear renormalization group equation in terms of the average value and the average fluctuation of extra color charge density generated by integrating out gluons with intermediate values of $x$. This form clearly exhibits the nature of the phenomena driving the evolution and should serve as the basis of the analysis of saturation effects at high gluon density at small $x$.Comment: 14 pages, late

Phenomenological description of the gamma* p cross section at low Q2

Low Q2 photon-proton cross sections are analysed using a simple, QCD-motivated parametrisation $\sigma_{\gamma^\star p}\propto 1/(Q^2+Q_0^2)$, which gives a good description of the data. The Q2 dependence of the gamma* p cross section is discussed in terms of the partonic transverse momenta of the hadronic state the photon fluctuates into.Comment: 14 pages, revtex, epsfig, 2 figure

New Global Defect Structures

We investigate the presence of defects in systems described by real scalar field in (D,1) spacetime dimensions. We show that when the potential assumes specific form, there are models which support stable global defects for D arbitrary. We also show how to find first-order differential equations that solve the equations of motion, and how to solve models in D dimensions via soluble problems in D=1. We illustrate the procedure examining specific models and finding explicit solutions.Comment: RevTex4, 4 pages, 3 eps figures; to be published in Phys. Rev. Let

Short-term genome stability of serial Clostridium difficile ribotype 027 isolates in an experimental gut model and recurrent human disease

Copyright: © 2013 Eyre et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are creditedClostridium difficile whole genome sequencing has the potential to identify related isolates, even among otherwise indistinguishable strains, but interpretation depends on understanding genomic variation within isolates and individuals.Serial isolates from two scenarios were whole genome sequenced. Firstly, 62 isolates from 29 timepoints from three in vitro gut models, inoculated with a NAP1/027 strain. Secondly, 122 isolates from 44 patients (2–8 samples/patient) with mostly recurrent/on-going symptomatic NAP-1/027 C. difficile infection. Reference-based mapping was used to identify single nucleotide variants (SNVs).Across three gut model inductions, two with antibiotic treatment, total 137 days, only two new SNVs became established. Pre-existing minority SNVs became dominant in two models. Several SNVs were detected, only present in the minority of colonies at one/two timepoints. The median (inter-quartile range) [range] time between patients’ first and last samples was 60 (29.5–118.5) [0–561] days. Within-patient C. difficile evolution was 0.45 SNVs/called genome/year (95%CI 0.00–1.28) and within-host diversity was 0.28 SNVs/called genome (0.05–0.53). 26/28 gut model and patient SNVs were non-synonymous, affecting a range of gene targets.The consistency of whole genome sequencing data from gut model C. difficile isolates, and the high stability of genomic sequences in isolates from patients, supports the use of whole genome sequencing in detailed transmission investigations.Peer reviewe