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We have defined the complex bed topography for a section of a small temperate glacier using 50 MHz monostatic short-pulse radar data and a synthetic-aperture array-processing method. The data were collected on a 100 m by 340 m array grid in the upper stem of Gulkana Glacier, central Alaska, U.S.A. The array processing was based on a modified three-dimensional (3-D) Kirchhoff migration integral and implemented with a synthetic-aperture approach that uses sequences of overlapping sub-arrays to generate depth images in vertical planes. Typical sub-array beam patterns are generally <5° at the −6 dB level, giving a flashlight-like searching capability without distorting the wavelet shape. The bed topography was constructed using normal reflections picked from 3-D array depth images. In some instances reflections were imaged outside the data-cover-age area. The bed surface dips steeply, both parallel and transverse to the direction of ice flow. The maximum observed depth is roughly 140 m. The 3-D method resolved bed dips up to 45°. In regions of steepest dip, it improved depth accuracy by 36% compared with raw data, and by 15% compared with standard two-dimensional (2-D) migration. Over 12 dB of signal-to-noise improvement and improved spatial resolution was achieved compared to raw data and 2-D migration. False bottom layering seen in the raw data and in 2-D migrations is not observed in the 3-D array results. Furthermore, loss of bottom reflections is shown by the 3-D migration to be attributable to the dip and curvature of the reflector, and not scattering losses or signal clutter from englacial inclusions.
Arrays of miniature focusing optics located at the focal plane can improve the performance of focal plane systems. By more completely collecting the light at the focal plane and concentrating it into a smaller spot size on the detector plane, the photodetector area can be substantially reduced. Increased gamma radiation hardening and noise reduction result from the decrease in photodetector surface area. Binary optics technology, a process for fabricating large arrays of diffractive optical elements, is especially attractive for infrared materials. In this paper, diffractive Fresnel microlens arrays containing over six thousand F/0.9 lenslets are patterned in the surface of CdTe substrates by successive photolithographic and Ar+ ion-beam-etching steps. Results on smaller arrays of monolithically integrated binary-optics lenslets with II-VI detectors, demonstrating enhanced photodetector responsivities, are presented for the first time.
The five-fold surface of the Al70 Pd21 Mn9 quasicrystal has been studied using STM, LEED and AES. STM images from surfaces which have been sputtered and annealed to 875 K reveal 20-30 Å protrusions that have been identified by others as Mackay-type clusters. Higher-resolution images reveal substructures in these clusters having dimensions 2-3 Å. Longer annealing times at 875 K produced large areas having flat terraces which were imaged with atomic resolution. The LEED pattern from this surface has sharp spots on a low background, and AES indicates that the surface is deficient in Mn relative to the bulk. For surfaces annealed to 1050 K for less than 2 hours, STM images indicate that cluster and terrace phases coexist, and a third phase having aligned arrays of clusters is identified which appears to be intermediate between the cluster and terrace phases.
Field experiments were conducted in Alabama during 1999 and 2000 to test the hypothesis that any glyphosate-induced yield suppression in glyphosate-resistant cotton would be less with irrigation than without irrigation. Yield compensation was monitored by observing alterations in plant growth and fruiting patterns. Glyphosate treatments included a nontreated control, 1.12 kg ai/ha applied POST at the 4-leaf stage, 1.12 kg/ha applied DIR at the prebloom stage, and 1.12 kg/ha applied POST at 4-leaf and postemergence directed (DIR) at the prebloom cotton stages. The second variable, irrigation treatment, was established by irrigating plots individually with overhead sprinklers or maintaining them under dryland, nonirrigated conditions. Cotton yield and all measured parameters including lint quality were positively affected by irrigation. Irrigation increased yield 52% compared to nonirrigated cotton. Yield and fiber quality effects were independent of glyphosate treatments. Neither yield nor any of the measured variables that reflected whole plant response were influenced by glyphosate treatment or by a glyphosate by irrigation interaction.
Objectives: The objectives were to
ascertain the value of a range of methods—including clinical
features, resting and exercise electrocardiography, and rapid access
chest pain clinics (RACPCs)—used in the diagnosis and early
management of acute coronary syndrome (ACS), suspected acute myocardial
infarction (MI), and exertional angina.
Questions remain about the long-term health impacts of the 1991 Gulf War on its veterans.
To measure psychological disorders in Australian Gulf War veterans and a military comparison group and to explore any association with exposure to Gulf War-related psychological stressors.
Prevalences of DSM–IV psychological disorders were measured using the Composite International Diagnostic Interview. Gulf War-related psychological stressors were measured using a service experience questionnaire.
A total of 31% of male Gulf War veterans and 21% of the comparison group met criteria for a DSM–IVdisorder first present in the post-Gulf War period. The veterans were at greater risk of developing post-Gulf War anxiety disorders including post-traumatic stress disorder, affective disorders and substance use disorders. The prevalence of such disorders remained elevated a decade after deployment. The findings can be explained partly as a ‘war-deployment effect‘. There was a strong dose–response relationship between psychological disorders and number of reported Gulf War-related psychological stressors.
Service in the 1991 Gulf War is associated with increased risk of psychological disorders and these are related to stressful experiences.
D. A. Butterfield, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA,
I. R. Jonasson, Geological Survey of Canada, Ottawa, Ontario, Canada,
G. J. Massoth, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA 98115, USA,
R. A. Feely, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Seattle, WA 98115, USA,
K. K. Roe, Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, WA 98195, USA,
R. E. Embley, Pacific Marine Environmental Laboratory, National Oceanic and Atmospheric Administration, Newport, OR 97365, USA,
J. F. Holden, School of Oceanography, University of Washington, Seattle, WA 98195, USA,
R. E. McDuff, School of Oceanography, University of Washington, Seattle, WA 98195, USA,
M. D. Lilley, School of Oceanography, University of Washington, Seattle, WA 98195, USA,
J. R. Delaney, School of Oceanography, University of Washington, Seattle, WA 98195, USA
A major challenge confronting geochemists is to relate the chemistry of vented hydrothermal fluids to the local or regional tectonic and volcanic state of mid-ocean ridges. After more than 15 years of sampling submarine hydrothermal fluids, a complex picture of spatial and temporal variability in temperature and composition is emerging. Recent time-series observations and sampling of ridge segments with confirmed recent volcanic eruptions (CoAxial and North Cleft on the Juan de Fu caridge and 9–10° N on the East Pacific Rise) have created a first-order understanding of how hydrothermal systems respond to volcanic events on the seafloor. Phase separation and enhanced volatile fluxes are associated with volcanic eruptions, with vapour-dominated fluids predominating in the initial post-eruption period, followed in time by brine-dominated fluids, consistent with temporary storage of brine below the seafloor. Chemical data for CoAxial vents presented here are consistent with this evolution. Rapid changes in output and composition of hydrothermal fluids following volcanic events may have a profound effect on microbiological production, macrofaunal colonization, and hydrothermal heat and mass fluxes. Size and location of the heat source are critical in determining how fast heat is removed and whether subseafloor microbial production will flourish. Co Axial event plumes may be a direct result of dyking and eruption of lavas on the seafloor.
A fluorescence confocal microscopy technique was employed
to obtain subsurface images of nerve and
microvascular structure in the vas deferens and colon of the living
rat. The use of dual labelling with vital
dyes and 2-channel confocal acquisition allowed differentiation of
microscopic structure at both low and
higher magnification. Characteristic staining patterns of nerves
and blood vessels were repeatedly obtained in
each tissue, suggesting the potential of this technique for studying
morphological changes associated with
surgical procedures and/or models of neuronal or vascular pathology.
Fibre optic confocal imaging (FOCI) enabled subsurface fluorescence
microscopy of the skin of hairless mice
in vivo. Application of acridine orange enabled imaging of the layers of
the epidermis. The corneocytes of
the stratum corneum, the keratinocytes in the basal layers and redundant
hair follicles were visualised at
depths greater than 100 μm. Cellular and nuclear membranes of keratinocytes
of the skin were visualised by
the use of acridine orange and DIOC5(3). Imaging of the skin after
injection of FITC-dextran revealed an
extensive network of blood vessels with a size range up to 20 μm.
Blood cells could be seen moving through
dermal vessels and the blood circulation through the dermal vascular
bed was video-taped. The fluorescent
dye 4-di-2-ASP showed the presence of nerves fibres around the hair
follicles and subsurface blood vessels.
Comparison was made between images obtained in vivo using FOCI and in vitro
microscopy and conventional histology. FOCI offers the potential
to study dynamic events in vivo, such as
blood flow, skin growth, nerve regeneration and many pathological
processes, in ways which have not previously been possible.
In 1990, a broadleaf weed growing on a cattle ranch in Hendry County in southwest Florida was identified as tropical soda apple (Solanum viarum Dunal), a species native to Argentina and Brazil (5) (Figure 1). Tropical soda apple (TSA) was apparently collected in Florida from Glades County in 1988 (University of Florida Herbarium) but was observed on the Hendry County ranch as early as 1987. Having foliage unpalatable to livestock, this noxious weed can infest a pasture or rangeland within one to two years resulting in lower stocking rates (animals per hectare). However, livestock and wildlife (feral hogs, deer, raccoons) will eat the fruit and disseminate the seed via feces. Fruit production occurs throughout the year (primarily September through May) thus providing high numbers (40000 to 50 000 per plant) of viable seed (75% germination) for seed dispersal. Our objectives are to alert those concerned with weed control of the presence of TSA in subtropical regions of the U.S., to discuss the ecology and taxonomy of this weed, and to indicate areas for future research.
Significant deficiencies in personal social networks and social support in non-psychotic psychiatric out-patients have been reported by Henderson and his colleagues. In a replication study, 50 non-psychotic psychiatric out-patients were compared with 50 matched controls. Patients reported spending less time in social interaction, but more time in unpleasant interaction during the previous week; they also had fewer attachment figures, close relatives and good friends and fewer social contacts than controls. However, the separate analysis of Neurotic and Retarded depressives (using the Present State Examination) failed to replicate all these findings in the Retarded depressives. It is concluded that these associations are confirmed in neurotic patients, but that the more severe depressive disorders require further investigation.
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