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We have previously reported on the uniqueness and potential of room-temperature spectrometry of low-energy x-rays with a mercuric iodide (HgI2) detector (1,2,3). In this paper we emphasize the use of HgI2 detectors for x-ray fluorescence (XRF) analysis.
Because no vacuum plumbing or cryogenic cooling is required, the design of a mercuric iodide room-temperature x-ray spectrometer is extremely simple. Our present design consists of coupling a detector directly to the first-stage FET in a modified Tennelec 161 D preamplifier and making the configuration “light-tight”. Aside from providing a suitable entrance window, there are no other requirements for routine spectroscopy.
Continued development of mercuric iodide (HgI2) detectors for x-ray spectroscopy at room-temperature has led to a considerable improvement in energy resolution and a better understanding of the various detector parameters which affect sensitivity. The basic properties of a mercuric iodide detector and some of its characteristics pertinent to x-ray fluorescence analysis have been previously reported (1,2,3). In this paper we present results of studies to determine the shape o£ peaks and continuum background. Also, the use of Hgl2 in characterizing water pollutants by XRF analysis has been investigated and compared to cryogenically cooled Si(Li) and room-temperature proportional counter systems.
Gene transfer by pronuclear injection has been accomplished in farm animals by a number of research groups. Applications of this technology for improving milk composition, producing pharmaceutical proteins and manipulating physiology are described. Recent developments in our understanding of gene expression at the molecular level will increase the precision with which genetic changes can be made by gene transfer.
Family-centered care provides family members with basic needs, which includes information, reassurance, and support. Though national guidelines exist, clinical adoption often lags behind in this area. The Geisinger Health System developed and implemented a program for reliable delivery of best practices related to family communication to patients and families admitted to the intensive care unit (ICU).
There was no statistically significant difference noted in family satisfaction as determined by FSICU–24 scores, including the Care and Decision Making constructs between the pre- and post-intervention pilot population. The percentage of families reporting the occurrence of a family conference showed only minimal improvement, from 46.5% before to 52.5% following the intervention (p = 0.565). This was mirrored by low numbers of documented family conferences by providers, suggesting poor uptake despite buy-in, use of electronic checklists, and repeated attempts at education.
Significance of results:
This paper reviews the challenges to and implications for implementing national guidelines in the area of family communication in an ICU coupled with the principles of clinical reengineering.
In the exciting field of low dimensional magnetic systems including surfaces, interfaces and thin-films, local spin density (LSD) functional ab initio electronic structure calculations have played a key role by not only providing a clearer understanding of the experimental observations but also predicting new systems with desired properties. Our extensive calculated results demonstrate that: (i) Magnetic clean surfaces or interfaces with inert substrates undergo strong magnetic moment enhancements; (ii) the strong interaction with nonmagnetic transition metals diminishes (completely in some cases) the ferromagnetism and usually stabilizes the antiferromag-netic configuration. By including spin-orbit coupling as a perturbation, (i) reliable results for the Magneto-crystalline anisotropy of ultra-thin films can be obtained using the state-tracking procedure, although the anisotropy energy is a few tenths of a MeV; (ii) spectra of the Magneto-optical Kerr effects and magnetic circular dichroism in the soft x-ray region can be determined.
A sol-gel method was used to prepare bulk, closed pore, amorphous alumina-silica. Films
prepared from this 47wt% A12O3-SiO2 composition were examined by SAW, ellipsometry and electrical measurements. The films were found to have a surface area of 1.1 cm2/cm2, a refractive index of 1.44 at 633 nm, and a relative permittivity of 6.2 at 200 KHz. These properties indicate potential applications as hermetic seals, barrier coatings, dielectric layers for capacitors and passivation coatings for electronic circuits.
In the alumina-silica system, the surface area of gels exhibit dependence upon both composition and the fluid in the pores during drying. Under controlled conditions, an anomalous drop in both the surface area and skeletal density of identically prepared gels occurs at a composition of 47% alumina. An effort has been made to understand the reasons for this phenomenon. The effect of various solution precursor systems has been investigated. Precursors that contain boehmite, or other colloidal species, do not exhibit low surface area/density at 47% alumina. Data from light scattering, infrared spectroscopy, and solution NMR will be discussed for the precursor system used to prepare low surface area gels. Data will be interpreted to determine the effect of solution structure on gel characteristics.
The repeatable growth of high quality thick layers of GaN by hydride vapor phase epitaxy generally requires buffer layers or other surface pretreatments to produce morphologically smooth films suitable for further device growth. Of the conditions for high quality GaN growth, proper film nucleation invariably contributes most to the overall growth of high quality films and the exclusion of impurities. We have studied a two step growth process which incorporates a low temperature HVPE grown nucleation layer and have compared it to films grown without buffer layers to determine how the impurity content and the dislocation networks change the overall film quality. Additionally we observe the formation of macroscopic steps during growth with step heights of ∼0.75 μm and terrace widths of ∼ 7 μm, which we attribute to the initial conditions of the low temperature nucleation layer prior to growth and to kinetically limited growth.
Over the past 40 years there have been marked shifts in arable farmland management that are widely believed to have had a considerable impact on flowering plants and invertebrates and the small mammals and birds that rely upon them. It is not yet possible to predict the dynamics of plants and invertebrates either with past or future changes in farmland management. This study investigates whether a basic invertebrate classification, formed of broad trophic groups, can be used to describe interactions between invertebrates and their resource plants and evaluate management impacts for genetically modified, herbicide-tolerant (GMHT) and conventional herbicide management in both spring- and winter-sown oilseed rape. It is argued that the analyses validate trophic-based approaches for describing the dynamics of invertebrates in farmland and that linear models might be used to describe the changes in invertebrate trophic group abundance in farmland when driven by primary producer abundance or biomass and interactions between invertebrates themselves. The analyses indicate that invertebrate dynamics under GMHT management are not unique, but similar to conventional management occurring over different resource ranges, and that dynamics differed considerably between spring- and winter-sown oilseed rape. Thus, herbicide management was of much lower impact on trophic relationships than sowing date. Results indicate that invertebrate dynamics in oilseed rape are regulated by a combination of top-down and bottom-up trophic processes.
Crops transformed to express Bacillus thuringiensis (Bt) toxins can cause close to 100% mortality of certain target pest species. This study assessed the effect of target pest reduction on the predatory insect Chrysoperla carnea (Stephens) in the presence of alternative prey. Numbers of lacewings recovered from Bt oilseed rape (cultivar Oscar, event O52) did not differ significantly from numbers of lacewings recovered from conventional oilseed rape in cage experiments with the target pest Plutella xylostella (Linnaeus) and the non-target pest Myzus persicae (Sulzer) when aphid densities were high. However, significantly fewer lacewings were recovered from Bt plants as aphid densities were lowered. Lacewing weights were not affected by plant type.
The Vulcan Nd:glass laser at the Central Laser Facility (CLF) is a
petawatt (1015 Watts) interaction facility, designed to deliver
irradiance on target of 1021W.cm−2 for the UK
and international user community. The facility came online to users in
2002 and considerable experience has been gained operating Vulcan in this
mode. The facility delivers a wide-ranging experimental program in
fundamental physics and advanced applications. This includes the
interaction of ultrahigh intensity light with matter, fast ignition fusion
research, photon induced nuclear reactions, electron and ion acceleration
by light waves, and the exploration of the exotic world of plasma physics
dominated by relativity. We report on the first year's operation of
the facility and the highlights of the experimental campaigns.
Due to an error, the published version of the paper differed from the final
version submitted by the authors. The section starting at page 271 with
“The beams are well collimated …” and finishing at the end
of the page, and the caption for figure 4 were to be replaced with an updated
version, submitted on 20 May 2002, which follows underneath.
One of the most exciting results recently obtained in the
ultraintense interaction research area is the observation of
beams of protons with energies up to several tens of megaelectron
volts, generated during the interaction of ultraintense picosecond
pulses with solid targets. The particular properties of these
beams (high brilliance, small source size, high degree of
collimation, short duration) make them of exceptional interest
in view of diagnostic applications. In a series of experiments
carried out at the Rutherford Appleton Laboratory (RAL) and
at the Lawrence Livermore National Laboratory (LLNL), the
laser-produced proton beams have been characterized in view
of their application as a particle probe for high-density matter,
and applied to diagnose ultraintense laser–plasma
interactions. In general, the intensity cross section of a proton
beam traversing matter will be modified both by collisional
stopping/scattering, and deflections caused by electric/magnetic
fields. With a suitable choice of irradiation geometry and target
parameters, the proton probe can be made mainly sensitive to
the electric field distribution in the object probed. Therefore,
point projection proton imaging appears as a powerful and unique
technique for electric field detection in laser-irradiated targets
and plasmas. The first measurements of transient electric fields
in high-intensity laser-plasma interactions have been obtained
with this technique.
In non-ruminant livestock the energy which can be derived from dietary cellulose and xylan is limited by the inefficient microbial fermentation of these polymers in the hind-gut. Furthermore, in poultry, cereal-derived plant structural polysaccharides impair normal digestive function through the formation of gel-like structures that trap nutrients which are therefore unavailable to the animal. The nutrition of non-ruminant livestock could be significantly improved by the depolymerization of plant structural polysaccharides, through the introduction of cellulase activity in the small intestines of these animals. This report describes the generation of transgenic animals with the capacity to express and secrete a functional endoglucanase from the exocrine pancreas.
The gene encoding endoglucanase E (celE) from Clostridium thermocellum was fused to the exocrine pancreas specific enhancer of the elastase I gene and the (β-globin polyadenylation signal, and used to create 14 lines of transgenic mice. A range of tissues were assayed for cellulase activity, using β-glucan and 4-methylumbelliferyl-β-D-cellobioside as substrates. The pancreas was also subjected to immunohistochemistry and in situ hybridization.