The specificity of plant defences

This article discusses the specificity of plant defences

A Case of Pseudo-xanthoma Elasticum Presenting with Ischaemic Claudication

AbstractA 37-year-old man presented with symptoms of intermittent claudication. Investigations revealed atypical calf vessel disease but no obvious aetiology. Ten years later he re-presented with worsening symptoms. CT angiography confirmed the atypical pattern of lower limb arterial disease but also noted calcification of the renal parenchyma, myocardium and scrotum. A diagnosis of pseudo-xanthoma elasticum was confirmed by skin biopsy. Pseudo-xanthoma elasticum is a rare condition that presents infrequently to vascular surgeons. Early recognition should prompt aggressive risk factor management to slow accelerated atherosclerosis. Clinicians should be aware of the clinical features of this condition to allow early diagnosis

Validity of a pictorial perceived exertion scale for effort estimation and effort production during stepping exercise in adolescent children

This is the author's PDF version of an article published in European Physical Education Review ©2002. The definitive version is available at http://epe.sagepub.com.Recent developments in the study of paediatric effort perception have continued to emphasise the importance of child-specific rating scales. The purpose of this study was to examine the validity of an illustrated 1 – 10 perceived exertion scale; the Pictorial Children’s Effort Rating Table (PCERT). 4 class groups comprising 104 children; 27 boys and 29 girls, aged 12.1±0.3 years and 26 boys, 22 girls, aged 15.3±0.2 years were selected from two schools and participated in the initial development of the PCERT. Subsequently, 48 of these children, 12 boys and 12 girls from each age group were randomly selected to participate in the PCERT validation study. Exercise trials were divided into 2 phases and took place 7 to 10 days apart. During phase 1, children completed 5 x 3-minute incremental stepping exercise bouts interspersed with 2-minute recovery periods. Heart rate (HR) and ratings of exertion were recorded during the final 15 s of each exercise bout. In phase 2 the children were asked to regulate their exercising effort during 4 x 4-minute bouts of stepping so that it matched randomly prescribed PCERT levels (3, 5, 7 and 9). Analysis of data from Phase 1 yielded significant (P<0.01) relationships between perceived and objective (HR) effort measures for girls. In addition, the main effects of exercise intensity on perceived exertion and HR were significant (P<0.01); perceived exertion increased as exercise intensity increased and this was reflected in simultaneous significant rises in HR. During phase 2, HR and estimated power output (POapprox) produced at each of the four prescribed effort levels were significantly different (P<0.01). The children in this study were able to discriminate between 4 different exercise intensities and regulate their exercise intensity according to 4 prescribed levels of perceived exertion. In seeking to contribute towards children’s recommended physical activity levels and helping them understand how to self-regulate their activity, the application of the PCERT within the context of physical education is a desirable direction for future research

Theoretical investigation on the possibility of preparing left-handed materials in metallic magnetic granular composites

We investigate the possibility of preparing left-handed materials in metallic magnetic granular composites. Based on the effective medium approximation, we show that by incorporating metallic magnetic nanoparticles into an appropriate insulating matrix and controlling the directions of magnetization of metallic magnetic components and their volume fraction, it may be possible to prepare a composite medium of low eddy current loss which is left-handed for electromagnetic waves propagating in some special direction and polarization in a frequency region near the ferromagnetic resonance frequency. This composite may be easier to make on an industrial scale. In addition, its physical properties may be easily tuned by rotating the magnetization locally.Comment: 5 figure

Site scientific mission plan for the Southern Great Plains CART Site, July--December 1999

The Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site was designed to help satify the data needs of the Atmospheric Radiation Measurement (ARM) program science team. The site scientific mission plan defines the scientific priorities for site activities during the 6-month period beginning 1 July 1999, and looks forward in lesser detail to subsequent 6-month periods. The primary purpose of this document is to provide scientific guidance for the development of plans for site operations. It also provides information on current plans to the ARM functional teams and serves to disseminate the plans more generally within the ARM program and among the members of the science team. This document includes a description of the operational status of the site and the primary site activities envisioned, together with information concerning approved and proposed intensive observation periods (IOPs). This plan is a living document that is updated and reissued every six months as the observational facilities are developed, tested, and augmented and as priorities are adjusted in response to developments in scientific planning and understanding

An extended and revised Lake Suigetsu varve chronology from ∼50 to ∼10 ka BP based on detailed sediment micro-facies analyses

Lake Suigetsu (Japan) is a key site for radiocarbon (14C) calibration and palaeo-environmental reconstruction in East Asia. Here we present a description of the sediment (micro)facies, which in combination with a new approach to varve interpolation allows construction of a revised varve based chronology that extends the previous 2012 varve based chronology by ∼10 ka, back to ∼50 ka BP. Challenges in varve counting and interpolation, which were previously discussed in detail only for the Last Glacial-Interglacial Transition, are described here back to ∼50 ka BP. Furthermore, the relative merits of varve counting by μXRF scanning and by thin-section microscopy are discussed. Facies analysis reveals four facies zones, their transitions driven by both local and climatic controls. The lamination quality of the sediment is highly variable and varve interpolation reveals that in the analysed time interval, on average, only 50% of the annual cycles are represented by seasonal layers. In the remaining years seasonal layers are indistinguishable, i.e. either did not form or were not preserved. For varve interpolation an advanced version of the Varve Interpolation Program was used, which enabled the construction of the longest, purely varve dated chronology published, despite long intervals of poor lamination quality. The calculated interpolation uncertainty is +8.9% and −4.6%, which is well within expectations considering the high degree of interpolation and the length of the record

Doppler-Free Spectroscopy of Weak Transitions: An Analytical Model Applied to Formaldehyde

Experimental observation of Doppler-free signals for weak transitions can be greatly facilitated by an estimate for their expected amplitudes. We derive an analytical model which allows the Doppler-free amplitude to be estimated for small Doppler-free signals. Application of this model to formaldehyde allows the amplitude of experimentally observed Doppler-free signals to be reproduced to within the experimental error.Comment: 7 pages, 7 figures, 1 table, v2: many small improvements + corrected line assignmen

Detection of Atmospheric Cherenkov Radiation Using Solar Heliostat Mirrors

The gamma-ray energy region between 20 and 250 GeV is largely unexplored. Ground-based atmospheric Cherenkov detectors offer a possible way to explore this region, but large Cherenkov photon collection areas are needed to achieve low energy thresholds. This paper discusses the development of a Cherenkov detector using the heliostat mirrors of a solar power plant as the primary collector. As part of this development, we built a prototype detector consisting of four heliostat mirrors and used it to record atmospheric Cherenkov radiation produced in extensive air showers created by cosmic ray particles.Comment: 16 latex pages, 8 postscript figures, uses psfig.sty, to be published in Astroparticle Physic

On The Low Frequency Quasi Periodic Oscillations of X-ray Sources

Based on the interpretation of the twin kilohertz Quasi Periodic Oscillations (kHz QPOs) of X-ray spectra of Low Mass X-Ray Binaries (LMXBs) to the Keplerian and the periastron precession frequencies at the magnetosphere-disk of X-ray neutron star (NS) respectively, we ascribe the low frequency Quasi Periodic Oscillations (LFQPO) and HBO (15-60 Hz QPO for Z sources or Atoll sources) to the periastron precession at some outer disk radius. The obtained conclusions include: all QPO frequencies increase with increasing the accretion rate. The obtained theoretical relations between HBO (LFQPO) frequency and the kHz QPO frequency are similar to the measured empirical formula. Further, the possible dynamical mechanism for QPO production is discussed.Comment: 6 pages, 2 figures, accepted by APSS, 200