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 email@example.com
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.
This paper describes the design and fabrication of a range of ‘gas cell’ microtargets produced by the Target Fabrication Group in the Central Laser Facility (CLF) for academic access experiments on the Orion laser facility at the Atomic Weapons Establishment (AWE). The experiments were carried out by an academic consortium led by Imperial College London. The underlying target methodology was an evolution of a range of targets used for experiments on radiative shocks and involved the fabrication of a precision machined cell containing a number of apertures for interaction foils or diagnostic windows. The interior of the cell was gas-filled before laser irradiation. This paper details the assembly processes, thin film requirements and micro-machining processes needed to produce the targets. Also described is the implementation of a gas-fill system to produce targets that are filled to a pressure of 0.1–1 bar. The paper discusses the challenges that are posed by such a target.
Supraglacial meltwater reaching a glacier bed can increase ice surface velocities via hydraulic jacking and enhanced basal sliding. However, the relationships between the structure of supraglacial drainage systems, sink-point distributions, glacier flow processes and the magnitude of interannual velocity variability are poorly understood. To explore the hypothesis that spatial variations in the rate and mechanisms of glacier flow are linked to variations in supraglacial drainage system structure and sink-point distribution across an ice cap, we mapped supraglacial drainage systems on Devon Ice Cap from Landsat-7 ETM+ imagery. Spatial patterns of surface velocity and interannual velocity variability were determined using gradient correlation applied to Landsat-7 ETM+ images. Velocity variability is greater in areas close to sink-point locations, presumably because hydrologically forced basal sliding and/or bed deformation are enhanced in such areas. The distribution and characteristics of supraglacial drainage systems may play an important role in determining the distribution of regions of basal sliding, highlighting the need for knowledge of the supraglacial drainage system structure and sink-point distribution to inform efforts to model the dynamic response of Arctic ice caps to future climate warming.
We present a heuristic model for the collisional evolution of material in a debris disk. This is used to consider the probability that the 2-3% brightness clump observed in the sub-mm Fomalhaut disk is caused by stochastic collisions between large planetesimals. While this simple model finds that the probability that the clump is caused by collisions is low (about 1 in 80,000), a more detailed model is required to ascertain its true likelihood.
The present study investigated whether whey (WH) protein, casein (CAS) protein or a carbohydrate placebo (PLA) consumed 30 min before sleep could acutely alter appetite or cardiometabolic risk the following morning. A total of forty-four sedentary overweight and obese women (BMI: 25·7–54·6 kg/m2) completed this stratified, randomised, double-blind, placebo-controlled study (WH: n 16, age 27·4 (sd 5·0) years; CAS: n 15, age 30·3 (sd 8·1) years; PLA: n 13, age 28·5 (sd 7·2) years). The participants came to the laboratory at baseline (visit 1) and again in the morning after night-time ingestion of either protein or PLA (visit 2). Visit 2 was conducted at least 48 h after visit 1. During visits 1 and 2, the following parameters were measured: appetite (hunger, satiety and desire to eat); resting metabolism; blood lipid and glucose levels; the levels of insulin, leptin, C-reactive protein, insulin-like growth factor-1, cortisol and adiponectin. Data were analysed using repeated-measures ANOVA. No group × time interactions were observed for the measured variables; however, a main effect of time was observed for increased satiety (P= 0·03), reduced desire to eat (P= 0·006), and increased insulin levels (P= 0·004) and homeostatic model assessment of insulin resistance values (P= 0·01) after the consumption of either protein or PLA. The results of the present study reveal that night-time consumption of protein or carbohydrate by sedentary overweight and obese women improves their appetite measures but negatively affects insulin levels. Long-term studies are needed to evaluate the effects of chronic consumption of low-energy snacks at night on body composition and cardiometabolic risk.
Whilst debris discs orbiting main-sequence stars are well studied, very little is known regarding their fate when the star evolves onto the giant branch. For intermediate mass (A-type) stars, giants provide a unique opportunity to detect planets using the radial velocity technique, otherwise prohibited by high jitter levels and rotationally broadened lines in main-sequence intermediate mass (A-type) stars. Such stars can provide key insights into the structure of planetary systems around intermediate mass stars. In our Herschel OT1 program (PI Bonsor) we searched for the presence of debris discs orbiting a sample of 36 subgiants, half of which have RV detected companions. Our best detection is the resolved debris disc orbiting κ CrB.
Large impacts in the outer parts of a planetary system will produce debris discs that display a strong, distinctive, asymmetry, which will last for 105 year timescales. Debris resulting from a large impact may be able to explain the asymmetries in some known debris discs that have hitherto been difficult to understand.
We explored the middle-Holocene decline of Tsuga canadensis by measuring the diameters of pollen grains in two lake-sediment cores from New England. We hypothesized that a drop in pollen size at the time of the decline followed by an increase in pollen diameters as Tsuga recovered during the late Holocene might indicate reduced abundance of Tsuga in the vicinity of the lake during the decline, as smaller pollen grains travel farther than larger ones. To provide context for this hypothesis, we also measured the diameters of Tsuga pollen grains in the surface sediments of sites spanning the modern-day gradient of Tsuga in New England. Both fossil records exhibited a reduction in pollen size during the interval of the middle-Holocene decline, with diameters similar to those observed in the upper sediments of those sites, yet larger than Tsuga pollen grains in the surface sediments of coastal sites beyond the modern range of Tsuga. This pattern suggests that Tsuga persisted in scattered, low-density populations during the middle Holocene, as it has remained on the landscape since European settlement.
Analyses of a sediment core from Little Pond, located in the town of Bolton, Massachusetts, provide new insights into the history of environmental and ecological changes in southern New England during the late Holocene. Declines in organic content and peaks in the abundance of Isoetes spores indicate reduced water depth at 2900–2600, 2200–1800, and 1200–800 calibrated years before present (cal yr BP), generally consistent with the timing of dry conditions in records from elsewhere in the northeastern United States. The Little Pond pollen record features little change over the last 3000 yr, indicating that the surrounding vegetation was relatively insensitive to these periods of drought. The 1200–800 cal yr BP dry interval, however, coincides with increased abundance of Castanea pollen, suggesting that the expansion of Castanea in southern New England may have been influenced by late-Holocene climatic variability.
A number of materials are available which exhibit thermochromic properties. These include the superionic materials (eg silver sulphide), phase transition materials (eg vanadium dioxide) and mixed valence materials (eg SmS). Such materials can be exploited as optical thin films and when incorporated into multilayer structures exhibit non-linear properties, particularly at wavelengths in the infra-red (1–12μm). The response of such devices is dependant on the degree of temperature rise produced in the active material, which in turn is dependant on the optical properties of the material and the heat sinking characteristics of the substrate. A summary is presented highlighting techniques for film deposition, multilayer device design and temporal response characteristics measured under conditions of pulsed irradiation.
Polycrystalline thin-film CdTe is one of the leading materials used in photovoltaic solar cells. One way to improve device performance and stability is through understanding how various process steps alter defect states in the CdTe layer. Low-temperature photoluminescence (PL) studies show a 1.456-eV PL peak in single-crystal CdTe that is likely due to a Cui-OTe defect complex. A similar peak, observed in as-deposited glass/SnO2:F/CdS/CdTe thin-film structures, strongly suggests a common origin. The 1.456-eV peak is also seen in a thin-film sample after performing the CdCl2 treatment needed for high efficiencies.
The extent to which grain boundaries (GBs) in polycrystalline materials may be detrimental, benign, or even beneficial is explored with numerical simulations in two dimensions. We focus on the effects of GB recombination in Cu(In,Ga)Se2 (CIGS) solar cells and its effects on solar-cell performance. The simulations predict that (1) for device effciency exceeding 17%, the effective GB recombination velocity must be less than 104 cm/s; (2) grain boundaries within the space-charge region (SCR) lower the open-circuit voltage, whereas the short-circuit current is reduced by grain boundaries in the bulk material; and (3) horizontal GBs are relatively benign unless they are located in the SCR. Modifications to the electronic structure near grain boundaries show that charge-induced band-bending at grain boundaries will most likely have a negative effect on device performance, whereas a down-shift in the valence-band energy at the grain surface can effectively passivate the GBs and reduce the effective recombination velocity. For the models considered, GBs generally have a deleterious effect on effciency, and GBs alone can not explain the apparent superiority of polycrystalline over single-crystalline CIGS materials.
Human cases of Q fever appear to be common in Northern Ireland compared to the rest of the British Isles. The purpose of this study was to describe the seroepidemiology of Coxiella burnetii infection in cattle in Northern Ireland in terms of seroprevalence and determinants of infection. A total of 5182 animals (from a stratified systematic random sample of 273 herds) were tested with a commercial C. burnetii phase 2 IgG ELISA. A total of 6·2% of animals and 48·4% of herds tested positively. Results from a multilevel logistic regression model indicated that the odds of cattle being infected with Q fever increased with age, Friesian breed, being from large herds and from dairy herds. Large dairy herd animal prevalence was 12·5% compared to 2·1% for small beef herds. Preliminary seroprevalence in sheep (12·3%), goats (9·3%), pigs (0%) rats (9·7%) and mice (3·2%) using indirect immunofluorescence is reported.
Mineralogy and Remote Sensing of Rocks, Soil, Dust, and Ices
P. R. Christensen, Planetary Exploration Laboratory Arizona State University Moeur Building 110D Tempe, AZ 85287, USA,
J. L. Bandfield, Arizona State University, MC 6305 Mars Space Flight Facility Tempe, AZ, USA,
A. D. Rogers, Department of Geosciences, SUNY at Stony Brook Stony Brook, NY 11794, USA,
Glotch R. T. D., Department of Geosciences, SUNY at Stony Brook Stony Brook, NY 11794, USA,
V. E. Hamilton, Hawaii Institute of Geophysics & Planetology, University of Hawaii, 1680 East-West Road, Honolulu, HI 96822, USA,
S. W. Ruff, Mars Space Flight Facility Arizona State University Moeur Building, Room 131 Tempe, AZ 85287-6305, USA,
M. B. Wyatt, Brown University, Department of Geological Science, 324 Brook Street Providence, RI 02912-1846, USA
The Thermal Emission Spectrometer (TES) on Mars Global Surveyor (MGS) mapped the surface, atmosphere, and polar caps of Mars from 1997 through 2006. TES provided the first global mineral maps of Mars, and showed that the surface is dominated by primary volcanic minerals (plagioclase feldspar, pyroxene, and olivine) along with high-silica, poorly crystalline materials. Differences in the abundances of these minerals were initially grouped into two broad compositional categories that correspond to basalt and basaltic andesite. Additional analysis has identified four surface compositional groups that are spatially coherent, revealing variations in the composition of the primary crust-forming magmas through time. In general, plagioclase, high-Ca clinopyroxene, and high-silica phases are the dominant mineral groups for most regions, with lesser amounts of orthopyroxene, olivine, and pigeonite. One of the fundamental results from the TES investigation was the identification of several large deposits of crystalline hematite, including those in Meridiani Planum, that were interpreted to indicate the presence of liquid water for extended periods of time. This interpretation led to the selection of Meridiani as the target for the Opportunity rover, the first time that a planetary landing site was selected on the basis of mineralogic information. Aqueous weathering may have formed some of the high-silica phases seen in TES spectra at high latitudes, and the Mars Express Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité (OMEGA) spectrometer has detected phyllosilicates and sulfates, typically formed by aqueous weathering and deposition, in several locations.
Mineralogy and Remote Sensing of Rocks, Soil, Dust, and Ices
S. W. Ruff, Mars Space Flight Facility Arizona State University, Moeur Building, Room 131 Tempe, AZ 85287-6305, USA,
P. R. Christensen, Planetary Exploration Laboratory Arizona State University, Moeur Building 110D Tempe, AZ 85287, USA,
T. D. Glotch, Department of Geosciences, SUNY at Stony Brook Stony Brook, NY 11794, USA,
D. L. Blaney, JPL MS 183-501 4800 Oak Grove Drive Pasadena, CA 91109, USA,
J. E. Moersch, Department of Earth & Planetary Science University of Tennessee, 1412 Circle Drive, Room 306 Knoxville, TN 37996, USA,
M. B. Wyatt, Brown University, Department of Geological Science, 324 Brook Street Providence, RI 02912-1846, USA
Two Miniature Thermal Emission Spectrometers (Mini-TES) operated successfully onboard the two Mars Exploration Rovers (MER) on the Martian surface, one at Gusev crater and the other at Meridiani Planum. Designed to provide remotely sensed information on the bulk mineralogy of surface materials, the Mini-TES instruments served to guide the rovers to targets of interest and extrapolate the observations made by the rovers' mechanical-arm-mounted instruments. The Mini-TES on the Spirit rover in Gusev crater observed a flat plain covered by rocks with an olivine-rich ((Mg,Fe)2SiO4) mineralogy and a soil-like unit mantled by airfall dust occurring between the rocks. The dust is a spectral match to dust observed at Meridiani Planum and across the globe. The soil is basaltic in composition, dominated by plagioclase (NaAlSi3O8–CaAl2Si2O8), pyroxene (Ca(Mg,Fe)Si2O6–(Mg,Fe)SiO3), and olivine that probably was produced in part from the breakdown of local rocks. Approximately 2.5 km from the Spirit lander, the Columbia Hills contain a remarkably diverse set of rocks distinct from the plains. Basaltic glass appears to dominate the mineralogy of various outcropping rocks while plagioclase dominates the float rocks that cover most of the north side of Husband Hill, the tallest of the Columbia Hills. Numerous exotic (out of place) rocks dot the hillside that likely were emplaced as impact ejecta in some cases and perhaps as volcanic intrusions in other cases. Onboard the Opportunity rover in Meridiani Planum, the Mini-TES observed a nearly rock-free plain covered in hematite (Fe2O3) spherules and basaltic sand.
G. J. Taylor, Hawaii Institute of Geophysics & Planetology, 1680 East-West Road, Post 504 Honolulu, HI 96822, USA,
S. M. McLennan, Department of Geosciences, SUNY Stony Brook Stony Brook, NY 11794-2100, USA,
H. Y. McSween, Department of Earth & Planetary, Science University of Tennessee, Knoxville, TN 37996-1410, USA,
M. B. Wyatt, Brown University, Department of Geological, Science 324 Brook Street Providence, RI 02912-1846, USA,
R. C. F. Lentz, University of Hawai'i at Manoa Hawai'i, Institute of Geophysics and Planetology 1680 East-West Road, POST 602 Honolulu, HI 96822, USA
Data from Martian meteorites, orbital remote-sensing instruments, and in situ measurements at robotic landing sites reveal that Mars has a heterogeneous surface composition. We use these data to infer the compositional and mineralogical nature of Martian igneous rocks. Basaltic rocks dominate, but highly mafic magmas also formed, producing cumulate rocks inside lava flows. Cumulate rocks also formed in intrusions. Evolved, silicic rocks occur, but are not abundant. The diversity of igneous rocks indicates several distinctive source regions in the Martian mantle. These sources probably formed early in Martian history as the result of crystallization in a magma ocean followed by overturn of an unstable cumulate pile. Shergottites alone represent at least two distinct mantle sources (assuming no crustal assimilation), with mixing between them, but could represent several distinct sources on the basis of initial Sr-isotopic compositions. The nakhlites may represent a somewhat complementary source, but there is clearly an additional source with subchondritic Ba/La. Surface Types 1 and 2 are probably composed of multiple types of igneous rock, possibly mixed with altered materials, and on average are different in trace element (K, Th) and Fe abundances. They may be derived from distinct mantle source regions. The crust appears to have been constructed by basaltic magmatism, some associated with primary differentiation (probably a magma ocean), the rest formed by partial melting during mantle overturn and other dynamic processes.
The NASA Star and Exoplanet Database (NStED) is a general purpose stellar archive with the aim of providing support for NASA's planet finding and characterization goals, stellar astrophysics, and the planning of NASA and other space missions. There are two principal components of NStED: a database of (currently) 140,000 nearby stars and exoplanet-hosting stars, and an archive dedicated to high precision photometric surveys for transiting exoplanets. We present a summary of the NStED stellar database, functionality, tools, and user interface. NStED currently serves the following kinds of data for 140,000 stars (where available): coordinates, multiplicity, proper motion, parallax, spectral type, multiband photometry, radial velocity, metallicity, chromospheric and coronal activity index, and rotation velocity/period. Furthermore, the following derived quantities are given wherever possible: distance, effective temperature, mass, radius, luminosity, space motions, and physical/angular dimensions of habitable zone. Queries to NStED can be made using constraints on any combination of the above parameters. In addition, NStED provides tools to derive specific inferred quantities for the stars in the database, cross-referenced with available extra-solar planetary data for those host stars. NStED can be accessed at http://nsted.ipac.caltech.edu.
The NASA Star and Exoplanet Database (NStED) is a general purpose stellar archive with the aim of providing support for NASA's planet finding and characterization goals, stellar astrophysics, and the planning of NASA and other space missions. There are two principal components of NStED: a database of (currently) 140,000 nearby stars and exoplanet-hosting stars, and an archive dedicated to high-precision photometric surveys for transiting exoplanets. We present a summary of the latter component: the NStED Exoplanet Transit Survey Service (NStED-ETSS), along with its content, functionality, tools, and user interface. NStED-ETSS currently serves data from the TrES Survey of the Kepler Field as well as dedicated photometric surveys of four stellar clusters. NStED-ETSS aims to serve both the surveys and the broader astronomical community by archiving these data and making them available in a homogeneous format. Examples of usability of ETSS include investigation of any time-variable phenomena in data sets not studied by the original survey team, application of different techniques or algorithms for planet transit detections, combination of data from different surveys for given objects, statistical studies, etc. NStED-ETSS can be accessed at http://nsted.ipac.caltech.edu.
Thoracic surgery requires immobilization of the operating area. Usually, this is achieved with one-lung ventilation (OLV), however this may still lead to some movement. High-frequency jet ventilation (HFJV) may be an alternative way of ventilation in thoracic surgery. The purpose of this study was to determine the effectiveness of HFJV as an alternative option to OLV for thoracic procedures.
Sixty patients were randomized to receive either HFJV (n = 29) or OLV (n = 31) during the operation. During the course of the study 10 patients were excluded (4 patients in HFJV group and 6 patients in OLV group). The following haemodynamic and ventilatory parameters were recorded: heart rate, systolic and mean blood pressure, ventricular stroke volume, cardiac index, systemic vascular resistance, peak inspiratory pressure, oxygen saturation, PaO2 and PaCO2. Overall parameters were documented before the initiation of the chosen mode of ventilation every 15 min during the operation.
Patients in both groups showed comparable cardiovascular function. Mean values of peak inspiratory pressure were significantly higher in the OLV group. Oxygen saturation values were statistically higher in the HFJV group. PaCO2 values were similar in both during surgery, but were higher in the OLV group after awakening. Mean values of shunt fraction were lower in the HFJV group. Lower values of peak inspiratory pressure were therefore associated with higher partial pressure of carbon dioxide levels in the HFJV group. In the OLV group, 44% of patients experienced a postoperative sore throat. Operating conditions were comparable.
HFJV is safe option, comparable to OLV and offers some advantages for open-chest thoracic procedures.