To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
In glacial environments particle-size analysis of moraines provides insights into clast origin, transport history, depositional mechanism and processes of reworking. Traditional methods for grain-size classification are labour-intensive, physically intrusive and are limited to patch-scale (1 m2) observation. We develop emerging, high-resolution ground- and unmanned aerial vehicle-based ‘Structure-from-Motion’ (UAV-SfM) photogrammetry to recover grain-size information across a moraine surface in the Heritage Range, Antarctica. SfM data products were benchmarked against equivalent datasets acquired using terrestrial laser scanning, and were found to be accurate to within 1.7 and 50 mm for patch- and site-scale modelling, respectively. Grain-size distributions were obtained through digital grain classification, or ‘photo-sieving’, of patch-scale SfM orthoimagery. Photo-sieved distributions were accurate to <2 mm compared to control distributions derived from dry-sieving. A relationship between patch-scale median grain size and the standard deviation of local surface elevations was applied to a site-scale UAV-SfM model to facilitate upscaling and the production of a spatially continuous map of the median grain size across a 0.3 km2 area of moraine. This highly automated workflow for site-scale sedimentological characterization eliminates much of the subjectivity associated with traditional methods and forms a sound basis for subsequent glaciological process interpretation and analysis.
Spatial studies of the emission line regions in planetary nebulae (PN) can provide insight into the physical and chemical environments across the nebulae. In a collaborative effort by the coauthors, a K-band Fabry-Perot etalon has been coupled with an advanced 256 × 256 InSb focal plane array at the Wyoming Infrared Observatory 2.3m telescope. This system permits us to obtain spatially resolved, 0.24″/pixel, moderate spectral resolution (R ≈ 800), flux-density IR emission line images of astronomical sources. We obtained continuum-subtracted images of Br γ, HeI 2.06 μm, the 2-μm UIR features, and the 3.3 μm PAH dust feature in the PN NGC 6572, NGC 7027, and NGC 7662. One objective was to determine the spatial morphology of two unidentified emission lines, UIR1−2.199 μm, and UIR2−2.287 μm (Geballe et al. 1991). These UIR lines appear in the spectra of many PN (Hora et al. 1997) and in the Orion Nebula (Luhman & Rieke 1996). Geballe et al. suggested that the UIR lines are most likely forbidden transitions and showed that the parent ion ionization potential is ≈ 30–40 eV, while the ionization potential for the ions themselves is 40–60 eV. Here we directly compare the distribution of the UIR emitters to that of the gas (H+,He+) and dust (PAHs).
To quantify myocardial blood flow in infants and children with mild or moderate aortic stenosis using adenosine-infusion cardiac magnetic resonance.
It is unclear whether asymptomatic children with mild/moderate aortic stenosis have myocardial abnormalities. In addition, cardiac magnetic resonance-determined normative myocardial blood flow data in children have not been reported.
We studied 31 infants and children with either haemodynamically normal hearts (n=20, controls) or mild/moderate aortic stenosis (n=11). The left ventricular myocardium was divided into six segments, and the change in average segmental signal intensity during contrast transit was used to quantify absolute flow (ml/g/minute) at rest and during adenosine infusion by deconvolution of the tissue curves with the arterial input of contrast.
In all the cases, adenosine was well tolerated without complications. The mean pressure gradient between the left ventricle and the ascending aorta was higher in the aortic stenosis group compared with controls (24 versus 3 mmHg, p<0.001). Left ventricular wall mass was slightly higher in the aortic stenosis group compared with controls (65 versus 50 g/m2, p<0.05). After adenosine treatment, both the absolute increase in myocardial blood flow (p<0.0001) and the hyperaemic flow significantly decreased (p<0.001) in children with mild/moderate aortic stenosis compared with controls.
Abnormal myocardial blood flow in children with mild/moderate aortic stenosis may be an important therapeutic target.
We report on the preparation and characterization of crystalline bismuth oxide thin films via Biased Target Ion Beam Deposition method. A focused blue laser (405nm) is used to write an array of dots in the bismuth oxide thin film and demonstrate clear and circular recording marks in form of “bubbles” or “little volcanos” (FWHM ∼500nm). Results indicate excellent static recording characteristics, writing sensitivity and contrast. The recording mechanism is investigated and is believed to be related to laser-induced morphology change.
The beginning of Damonon's votive slab, which was found by Leake in the Monastery of the Holy Forty ("Αγιοι Τεσσαράκοντα or Σαράντα) and is now in the Sparta Museum, is one of the best known and oftenest discussed of early Laconian inscriptions.
The following are the chief references. Leake, Travels in the Morea, ii. 521 and Plate 71 (end of vol. iii.). A better copy, Dressel and Milchhöfer, Ath. Mitt. ii. 318. Facsimile in Roehl, I.G.A. 79 and Imagines2x. n. 16, p. 28 ; Fick, Bezz. Beiträdge, iii. 121 ff.; Collitz-Bechtel, iii. 4416 ; Roberts, Introd. to Gk. Epigr. i. n. 264 ; Tod, Sparta Mus. Cat. n. 440. (Other references, none of them of much importance, are given by Tod and Roehl, ll. c.)
The presence of 10 virulence genes was examined using polymerase chain reaction (PCR) in 365 European O157 and non-O157 Escherichia coli isolates associated with verotoxin production. Strain-specific PCR data were analysed using hierarchical clustering. The resulting dendrogram clearly separated O157 from non-O157 strains. The former clustered typical high-risk seropathotype (SPT) A strains from all regions, including Sweden and Spain, which were homogenous by Cramer's V statistic, and strains with less typical O157 features mostly from Hungary. The non-O157 strains divided into a high-risk SPTB harbouring O26, O111 and O103 strains, a group pathogenic to pigs, and a group with few virulence genes other than for verotoxin. The data demonstrate SPT designation and selected PCR separated verotoxigenic E. coli of high and low risk to humans; although more virulence genes or pulsed-field gel electrophoresis will need to be included to separate high-risk strains further for epidemiological tracing.
V- and I-band observations were taken over 9 months to study the RR Lyrae population in the metal-poor diffuse globular cluster NGC 6101. We identify one new variable, which is either a potential long-period red giant variable or eclipsing binary, and recover all previously identified RR Lyraes. One previously studied RR Lyrae is reclassified as an RRc type, while two period estimations have been significantly refined. We confirm that NGC6101 is Oosterhoff type II with a high ratio of n(c)/n(ab + c) = 0.833 with a very long mean RRab period of 0.86 d. By using theoretical RRLyrae period-luminosity-metallicity relations, we use our V- and I-band RR Lyrae data to gain an independent estimate of the reddening towards this cluster of E(B − V) = 0.15 ± 0.04 and derive a distance of 12.8 ± 0.8 kpc. The majority of the work in this study was undertaken by upper secondary school students involved in the Space to Grow astronomy education project in Australia.
Imputation of moderate-density genotypes from low-density panels is of increasing interest in genomic selection, because it can dramatically reduce genotyping costs. Several imputation software packages have been developed, but they vary in imputation accuracy, and imputed genotypes may be inconsistent among methods. An AdaBoost-like approach is proposed to combine imputation results from several independent software packages, i.e. Beagle(v3.3), IMPUTE(v2.0), fastPHASE(v1.4), AlphaImpute, findhap(v2) and Fimpute(v2), with each package serving as a basic classifier in an ensemble-based system. The ensemble-based method computes weights sequentially for all classifiers, and combines results from component methods via weighted majority ‘voting’ to determine unknown genotypes. The data included 3078 registered Angus cattle, each genotyped with the Illumina BovineSNP50 BeadChip. SNP genotypes on three chromosomes (BTA1, BTA16 and BTA28) were used to compare imputation accuracy among methods, and the application involved the imputation of 50K genotypes covering 29 chromosomes based on a set of 5K genotypes. Beagle and Fimpute had the greatest accuracy among the six imputation packages, which ranged from 0·8677 to 0·9858. The proposed ensemble method was better than any of these packages, but the sequence of independent classifiers in the voting scheme affected imputation accuracy. The ensemble systems yielding the best imputation accuracies were those that had Beagle as first classifier, followed by one or two methods that utilized pedigree information. A salient feature of the proposed ensemble method is that it can solve imputation inconsistencies among different imputation methods, hence leading to a more reliable system for imputing genotypes relative to independent methods.
A key component of social work ethics is social justice and equitable access to resources. Increasingly, this includes access to technology. This study addresses issues related to the ‘digital divide’ by testing a peer tutor model (Technology and Aging Project, TAP2) to teach adults aged 60 and older how to use information and communication technologies (ICTs) such as email, the internet, online chat rooms and discussion groups, internet-based support groups, and voice technology and webcams. Participants from the control group of a previous programme, TAP1 (N=19) participated in a six-month computer training programme. Six participants who had successfully completed the TAP1 training were selected to be peer tutors. Data were collected from tutors and learners at baseline, three months, six months and nine months (three months after the end of training). The current study reports on learner outcomes only. Measures include computer, social support, and mental health-related outcomes. Learners reported a significant and consistent increase over time in their confidence completing certain computer-related tasks and their overall use of ICTs. Mental health and social support outcomes did not change. Overall, the peer tutor model appeared to be at least as effective as the previous staff-directed model.
Salmonella is the second most commonly reported human foodborne pathogen in England and Wales, and antimicrobial-resistant strains of Salmonella are an increasing problem in both human and veterinary medicine. In this work we used a generalized linear spatial model to estimate the spatial and temporal patterns of antimicrobial resistance in Salmonella Typhimurium in England and Wales. Of the antimicrobials considered we found a common peak in the probability that an S. Typhimurium incident will show resistance to a given antimicrobial in late spring and in mid to late autumn; however, for one of the antimicrobials (streptomycin) there was a sharp drop, over the last 18 months of the period of investigation, in the probability of resistance. We also found a higher probability of resistance in North Wales which is consistent across the antimicrobials considered. This information contributes to our understanding of the epidemiology of antimicrobial resistance in Salmonella.
The mechanical behavior of intermetallic alloys is related to crystal bonding and the influence of bonding on the core structure of dislocations formed in these compounds. These combined effects influence the deformation behavior in an, as yet, undefined manner. However, in a way that gives rise to unusual behavior, such as the anomalous temperature dependence of flow stress observed in TiAl. Recent studies have suggested a particular relationship between the directional bonding in TiAl and dislocation mobility. To better understand the flow behavior of intermetallics, and as a beginning toward bridging the gap between electronic structure and flow behavior, we have calculated the electronic structure of various planar faults in TiAl. The self consistent electronic structure has been determined using the layered Korringa Kohn Rostoker (LKKR) method which embeds the region containing the defect between two semi-infinite perfect crystals. Calculated defect energies agree reasonably well with other theoretical estimates, though overestimating experimental values. The changes in bonding taking place in the vicinity of the planar defect will be discussed and illustrated through the density of states and charge density plots.
The corrosion behavior of TiCode-12 (Ti-0.3 Mo-0.8 Ni) high level nuclear waste container alloy has been studied for a simulated WIPP brine at a temperature of 150°C or below. Crevice corrosion was identified as a potentially important failure mode for this material. Within a mechanical crevice, a thick oxide film was found and shown to be the rutile form of TiO2, with a trace of lower oxide also present. Acidic conditions were found to cause a breakdown of the passive oxide layer. Solution aeration and increased acidity accelerate the corrosion rate. In hydrogen embrittlement studies, it was found that hydrogen causes a significant decrease in the apparent stress intensity level in fracture mechanics samples. Hydride formation is thought to be responsible for crack initiation. Stress corrosion cracking under static loads was not observed. Attention has also been given to methods for extrapolating short term uniform corrosion rate data to extended times.
Crystal damage of GaAs(100) caused by Reactive Ion Etching (RIE) using a mixture of Cl2 and Ar gas has been assessed using Surface Roughness (Ra), Resonant Raman Spectroscopy (RRS), Schottky diodes, and Spectroscopic Ellipsometry (SE). Plasma conditions for minimum induced damage have been determined and compared to optimised RIE processes using plasma gases SiCl4, CH4-H2, CCl2F2 and Ar. The SiCl4 plasma was found to produce the least crystal damage.
Cost effective high volume manufacture (HVM) is a major challenge to the success of solid oxide fuel cells (SOFCs). More than fifteen processing methods have been reported in the literature many of which could be used in various combinations to create the desired product characteristics. Modeling tools are needed to aid in the selection of the appropriate process combination prior to making expensive investment decisions.
This paper describes the development of a multi-process cost model that permits the comparison of manufacturing cost for different processing combinations and various materials. Two specific processing methods are discussed, tape casting and screen printing.
The results are compared with data and experience from the fuel cell and electronic packaging industries. Initial comparisons show good agreement with this experience base. Sensitivity of manufacturing costs to SOFC performance requirements such as maximum power density and operation temperature is investigated.
The rational design of crystal structures, in particular noncentrosymmetric materials, and how to differentiate polar, polar-chiral, and chiral structures, is an ongoing theme in crystal engineering. In KNaNbOF5, the combination of a second-order Jahn Teller active d0 transition metal oxyfluoride anionic unit and mixed K/Na cation coordination environments are shown to result in a polar structure (space group Pna21). The crystal structure analysis of the Na/K-O/F interactions reveals that the potassium cations form one of the two contacts to the under-bonded oxide ions. These interactions satisfy the expected bond valence sums and Pauling's second crystal rule (PSCR), leading to O/F ordering and acentric packing of the [NbOF5]2− anionic unit.