bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved image quality for x‐ray CT imaging of gel dosimeters
Authors: Kakakhel M. B. , Kairn T. , Kenny J. , Trapp J. V. 
Published: August 2011

Purpose:This study provides a simple method for improving precision of x‐ray computed tomography (CT) scans of irradiated polymer gel dosimetry. The noise affecting CT scans of irradiated gels has been an impediment to the use of clinical CT scanners for gel dosimetry studies.Methods:In this study, it is shown that multiple scans of a single PAGAT gel dosimeter can be used to extrapolate a “zero‐scan” image which displays a similar level of precision to an image obtained by averaging multiple CT images, without the compromised dose measurement resulting from the exposure of the gel to radiation from the CT scanner.Results:When extrapolating the zero‐scan image, it is shown that exponential and simple linear fits to the relationship between Hounsfield unit and scan number, for each pixel in the image, provide an accurate indication of gel density.Conclusions:It is expected that this work will be utilized in the analysis of three‐dimensional gel volumes irradiated using complex radiotherapy treatments.
The Princess Marina Hospital accident and emergency triage scale provides highly reliable triage acuity ratings
Authors: Twomey Michele , Mullan Paul C , Torrey Susan B , wallis Lee , Kestler Andrew 
Published: August 2011

ObjectiveTo determine the interrater reliability of triage acuity ratings by healthcare workers (HCW) using a previous triage system (PTS) and the Princess Marina Hospital accident and emergency centre triage scale (PATS), a local adaptation of the widely used and studied South African triage scale.MethodsA cross-sectional study was performed on HCW in an emergency department (ED) in Botswana to determine the interrater reliability of triage acuity ratings when using PTS and PATS to assign triage categories to 25 written vignettes after PATS training. The intraclass correlation coefficient (ICC) was calculated to assess interrater reliability, and graphic displays were used to portray rating distributions for vignettes with a mean rating of different acuity categories for PTS and PATS.Results44 HCW completed the scenarios. The ICC for the group of HCW was 0.52 (95% CI 0.37 to 0.67) using PTS and 0.87 (95% CI 0.80 to 0.93) using PATS. The ICC values were higher for PATS than PTS regardless of the number of years of experience of the HCW and the level of the HCW (specialist, medical officer, nurse, nurse aide). Graphic displays showed that there was less variability at all acuity levels when using PATS compared with PTS.ConclusionThe reliability measures in this study indicate very high interrater agreement and limited variability in acuity ratings when using the PATS as opposed to moderate agreement and increased variability in acuity ratings when using PTS. This suggests that PATS is reliably applied by all levels of HCW and supports the feasibility of the further implementation of PATS in ED in Botswana and in other similar settings.
Continued use of the Standard Days Method®
Authors: Sinai Irit , Lundgren Rebecka I , Gribble James N 
Published: August 2011

ObjectiveTo examine the long-term effectiveness and continuation of the Standard Days Method (SDM)®, a fertility awareness-based method of family planning that identifies Days 8–19 (inclusive) of the cycle as the fertile window. On these days users avoid unprotected sexual intercourse to prevent pregnancy. The method works best for women with cycles that are usually in the range of 26–32 days, which is an important reason for method discontinuation in the first year of use. The authors determine if this continues to be an issue in the second and third years of method use.MethodsParticipants in an earlier efficacy study (478 women in three countries) and method introduction studies (1181 women in four countries) were followed for 2 years beyond the original 1-year study period, to determine their continued use of the method, intended and unintended pregnancies, and reasons for discontinuation. Life-tables were used to approximate typical use pregnancy rates.ResultsThe method continues to be effective in the second and third years of use, and compares favourably to other user-directed family planning methods. Women with no more than two cycles outside the 26–32-day range within a year are likely to continue having cycles within this range.ConclusionsWomen who complete the first year of SDM use are likely to continue to be able to use the method successfully and effectively. The method presents a viable longer-term option for women who prefer this approach to family planning.
The Standard Days Method®: an addition to the arsenal of family planning method choice in Ethiopia
Authors: Bekele Biruhtesfa , Fantahun Mesganaw 
Published: August 2011

Background and methodologyThe Standard Days Method® (SDM) is a fertility awareness-based method of family planning that helps users to identify the fertile days of the reproductive cycle (Days 8–19). To prevent pregnancy users avoid unprotected sexual intercourse during these days. A cross-sectional community-based study was conducted from December 2007 to June 2008 in four operational areas of Pathfinder International Ethiopia. A total of 184 SDM users were included in the study. Quantitative and qualitative methods of data collection were used. The aim of the study was to examine the experience of introducing the SDM at community level in Ethiopia.ResultsOf the 184 participants, 80.4% were still using the SDM at the time of the survey, with 35% having used it for between 6 and 12 months, while 42% had used it for more than a year. The majority (83%) knew that a woman is most likely to conceive halfway through her menstrual cycle, and nearly 91% correctly said that the SDM does not confer protection from sexually transmitted infections/AIDS. A substantial majority (75%) had correctly identified what each colour-coded bead represents in the CycleBeads®, and an aggregate of 90.5% of women practised all the elements of correct use.Discussion and conclusionsThis study demonstrates the importance of the SDM in increasing the availability and accessibility of family planning, and the potential to improve family planning method choice and method mix by expanding use of the SDM.
Fill and spill in Lethe Vallis: a recent flood-routing system in Elysium Planitia, Mars
Authors: Balme M. R. , Gallagher C. J. , Gupta S. , Murray J. B. 
Published: August 2011

Abstract
Lethe Vallis is an approximately 230 km-long and 1.5 km-wide channel connecting several shallow basins in the Elysium Planitia region of Mars. It sits within a distinctive morphological unit defined by a platy-ridged-polygonized texture. We have documented the geomorphology of the system, and constructed topographical long profiles of the channel thalweg and the contacts of the platy-ridged-polygonized material.

The Lethe thalweg is shallow (with a slope of about 0.0001) but contains steeper sections that match the locations of observed cataract systems. The contact profiles suggest that the small basins linked by Lethe progressively ponded and over-spilled as the system developed, the cataracts being associated with this over-spill. Other landforms observed in the system include streamlined islands, anastomosing distributary systems, fluvial hanging channels and terraces on the channel margins. There are also possible dunes and/or antidunes within the channel. These all point to catastrophic fluvial flooding. Estimates of formative discharge are of the order of 1×10
4
–5×10
4
m
3
s
−1
, similar to the discharge of the Mississippi River.

We infer that Lethe Vallis formed as a fluvial ‘fill and spill’ catastrophic flood system. This demonstrates that the main Western Elysium Basin, the upstream source of Lethe Vallis, contained a substantial transient lake.
Geologically recent water flow inferred in channel systems in the NE Sulci Gordii region, Mars
Authors: Towner M. C. , Eakin C. , Conway S. J. , Harrison S. 
Published: August 2011

Abstract

A series of fluid-carved channels in the Sulci Gordii region of Mars were investigated. Numerous channel networks exist in Sulci Gordii, part of the Olympus Mons aureole, and this area comprises some of the youngest volcanic terrain on Mars. The channels ranged in length from 43 to 155 km, with widths of 128–288 m. The morphology of the channels was analysed assuming both lava and water as possible agents. For three of the four channels studied, water appears to be the likely agent, while one channel is probably lava-formed. For the water-formed channels, discharge rates were estimated at 8000–36 000 m
3
s
−1
. The lava channel was probably formed from short-lived episodic activity by a low-viscosity lava. The age of the channels and surrounding area was estimated using crater counting to be 100 Ma. Water has appeared to have flowed for almost 150 km under the climatic conditions at this time. There is some evidence for later tectonic activity, possibly as recent as 10 Ma, but crater-dating accuracy was limited by the lack of high-resolution images of some areas. Sulci Gordii is therefore a dynamic site with evidence of hydrological and volcanic activity extending into the recent geological past.
Layering and degradation of the Rupes Tenuis unit, Mars – a structural analysis south of Chasma Boreale
Authors: Kneissl T. , Van Gasselt S. , Wendt L. , Gross C. , Neukum G. 
Published: August 2011

Abstract
The circum north-polar Rupes Tenuis unit forms the polar-proximal basal stratigraphical and morphological units that delineate the north polar cap between 180° and 300°E. In the region of the mouth of the Chasma Boreale re-entrant, the Rupes Tenuis unit is likely to extend further southwards into the northern plains. This is suggested by the occurrence of isolated remnants that have been interpreted as basaltic shield volcanoes, maar craters or mud volcanoes in the past.

As key elements of this study, we assessed the quantitative characteristics of this unit using layer attitudes derived from high-resolution images and terrain-model data, and by performing cross-correlations of prominent layers whose outcrops are observed at eight cone-like remnants. The identification and unambiguous correlation of characteristic layers across the study area provided a reasonable basis for introducing at least three additional stratigraphical subunits of the Rupes Tenuis unit. Extrapolation of altitude data indicates a gentle southward dip of remnant layers, suggesting that the unit had a much larger areal extent in Martian history. The palaeo-layer contact between two subunits of the Rupes Tenuis unit correlates well with elevation values of the Hyperborea Lingula surface. Both results disagree with an interpretation of a volcanic origin for isolated mesas but underpin that they are erosional relicts of the Rupes Tenuis unit. Average erosion rates of 2.5×10
−4
±4×10
−5
mm year
−1
are relatively high when compared to Amazonian rates but are not exceptional for areas undergoing deflation. They also corroborate the idea of aeolian denudation of the Rupes Tenuis unit.
A comparative study of interior layered deposits on Mars
Authors: Sowe Mariam , Jaumann Ralf , Neukum Gerhard 
Published: August 2011

Abstract
Interior layered deposits (ILDs) of the eastern Valles Marineris and adjacent chaos regions were analysed using high-resolution imagery, topography and spectral data in order to detect possible correlations. We find that ILDs are susceptible to erosion and weathering, as proven by their shapes (mesa, buttes), surface structures (pitted, fluted, yardangs), stair-stepped morphologies at different scales, and metre-sized boulders and talus. ILDs bear hydrated sulphates; consequently, we conclude that aqueous conditions dominated during their formation. Subhorizontal layering and parallel bedding of the ILDs could then indicate that deposition took place under low-energy aquatic conditions. Their superposition on chaotic terrain suggests that they are younger than chaotic terrain and, hence, younger than Late Hesperian. For the hydrated ILDs, which show polyhydrated on top of monohydrated sulphates, we think that formation within an evaporative body is not conceivable and we assume instead that a conversion of sulphates by post-formational humidity changes took place. As hydrated ILDs correlate well with rock fragmentation, we suppose that volume changes due to water content are responsible for rock fragmentation. Despite the different ILD settings, the basic conditions during sedimentation and erosion of ILDs could not have varied greatly because comparable mineralogies and morphologies are found among ILDs.
A background to Mars exploration and research
Authors: Bargery Alistair S. , Balme Matthew R. , Warner Nicholas , Gallagher Colman J. , Gupta Sanjeev 
Published: August 2011

Abstract

Mars is the fourth planet in our Solar System and orbits roughly 230×10
6
km from the Sun. It has an orbital period of 687 Earth days and a solar day that is approximately 40 min longer than an Earth day. Mars is less dense and has half the radius of the Earth, and so has about one-tenth the mass; hence, the surface gravity of Mars is about four-tenths that of the Earth. Mars has no oceans and its surface area is therefore almost as large as that of Earth's continents. In this chapter, we present a summary of the Martian environment, global geography and geology, and provide some background on the missions and instruments that have played a role in developing our current understanding. Our aim is to provide a broad overview for those unfamiliar with Mars, rather than providing an exhaustive summary of every aspect of the planet's evolution.
Morphological and geographical evidence for the origin of Phobos' grooves from HRSC
Mars Express
images
Authors: Murray John B. , Iliffe Jonathan C. 
Published: August 2011

Abstract

The surface of Phobos, the 27×22×18 km inner moon of Mars, is dominated by several families of parallel grooves. At least seven different groups of hypotheses have been advanced to explain their origin, but studies have always been limited by the fact that, until recently, much of Phobos was imaged at a resolution too low to show grooves. Now, however, the High Resolution Stereo Camera (HRSC) on board the European
Mars Express
mission has made 134 imaging fly-bys past Phobos. The pictures of the previously poorly imaged regions and much of the rest of the satellite have been returned with resolutions down to a few metres, facilitating the construction of a more complete map of the grooves. Each of the seven hypotheses was tested against the new data on groove morphology, positions and orientations, and it was found that six of the previous hypotheses could be discarded. The only hypothesis to pass all tests was that they are chains of secondary impact craters from primary impacts on Mars. An implication of these results is that previous estimates of an unusually thick Phobos regolith of 100–200 m depth are no longer necessary, and our conclusions place no constraints on the interior of Phobos, so recent evidence that Phobos is a ‘rubble pile’ is consistent with our work. The preferred hypothesis also sheds light on the origin of crater chains on Eros, and on impact processes in the early stages of crater excavation.
Periglacial geomorphology and landscape evolution of the Tempe Terra region, Mars
Authors: Van Gasselt S. , Hauber E. , Rossi A.-P. , Dumke A. , Orosei R. , Neukum G. 
Published: August 2011

Abstract
A systematic survey was undertaken and an investigation carried out into the geomorphological characteristics of lobate debris aprons in the Tempe Terra region of Mars. Based on the most recent high-resolution (sub 15 m per pixel) imagery and on new topography data, this study endeavoured to raise and discuss questions regarding their formation (emplacement) and modification (deformation sequence), as well as the role of a mantling deposit found at mid-latitude locations on Mars. Furthermore, a model for the formation of debris aprons in the Tempe Terra–Mareotis Fossae settings is proposed. Image survey, in combination with basic morphometric observations within a geomorphological context, provided additional insights into the source, emplacement and modification of hillslope debris material. Our results imply that lobate debris aprons are not mainly relicts of remnant degradation but are substantially composed of mantling material probably deposited episodically in the course of planetary obliquity changes and over a long timespan, as derived erosion rates suggest. Crater-size frequency statistics and the derivation of absolute ages show ages of sub-recent modification and document earlier resurfacing events.
Evolution of periglacial landforms in the ancient mountain range of the Thaumasia Highlands, Mars
Authors: Rossi Angelo Pio , Van Gasselt Stephan , Pondrelli Monica , Dohm James , Hauber Ernst , Dumke Alexander , Zegers Tanja , Neukum Gerhard 
Published: August 2011

Abstract
Possible periglacial and relict glacial landforms in the ancient mountain range of the Thaumasia Highlands, Mars, are described. The landforms include large-scale mantling, lineated crater and valley-fill materials, debris aprons, protalus lobes and ramparts. The most pristine ice-related landforms appear to be small-scale protalus lobes and ramparts with no visible distinct impact craters at both medium (High Resolution Stereo Camera (HRSC)) and high (Mars Orbiter Camera (MOC) narrow angle (NA), Context Camera (CTX)) spatial resolution. These small landforms are possibly active at present and post-date more extensive features such as crater fills, possibly formed during high obliquity climatic periods.
In contrast to the rock glacier-like landforms with distribution preferentially occurring on south-facing slopes, possibly controlled by enhanced exposure to the Sun, older, less pristine lineated fill materials show a less systematic distribution of flow directions, suggesting a more generalized periglacial and possibly glacial environment in the Thaumasia Highlands.
Landforms indicative of ground-ice thaw in the northern high latitudes of Mars
Authors: Gallagher C. J. , Balme M. R. 
Published: August 2011

Abstract

The confirmation of near-surface ground ice and perchlorates at the
Phoenix
landing site suggest that high-latitude ground-ice thaw may be more easily achieved than previously envisaged, providing the potential to drive significant, distinctive morphogenesis. We describe the results of a survey of 23 High Resolution Imaging Science Experiment (HiRISE) images covering 337° of longitude between latitudes 59°N and 79°N in which such morphogenesis is apparent, confirming that thaw has been a regionally important morphological agent. Some of the strongest geomorphological indicators of cyclical ground-ice thaw described are assemblages of sorted landforms, including clastic patterned ground resulting from cryoturbation of ice-rich regolith and lobate forms reflecting solifluction. Also described are braided gully-fan systems sourced at thermokarst pits and channels that have evolved from enlarged thermal contraction cracks. Not only are these landforms indicative of thaw and flowing liquid but the incision of solifluction lobes by thermokarst gullies demonstrates that thaw has been responsible for polycyclic morphogenesis. The presence of these landforms across the high northern latitudes of Mars indicates that the regional importance of thaw has been underestimated. This in turn has important implications for the development of better climate models and the search for life on Mars.
Water ice sublimation-related landforms on Mars
Authors: Mangold N. 
Published: August 2011

Abstract
Sublimation-related landforms are ubiquitous on Mars, especially at mid to high latitudes. This paper reviews the main landforms interpreted to form due to sublimation of subsurface ice on Mars. Pits, knobs and dissected terrains are classical landforms thought to form due to subsurface ice sublimation as observed with high-resolution imagery. Sublimation-related processes on Mars are strongly latitude dependent, with sublimation being increasingly important from high (>60°) to low latitudes (down to 25°) due to correspondingly higher mean annual temperatures. Equatorial regions (within 25° latitude) are mainly devoid of any sublimation-related landforms, reflecting an ice-free shallow subsurface. Mean temperatures and water vapour pressure strongly control the sublimation rate, but diffusion and water adsorption are fundamental and vary depending on the regolith porosity and composition, leading to variations in the theoretical depth at which water ice becomes stable. From a geomorphological point of view, this review highlights the importance of subsurface structure (fractures, layering) in the shaping of landforms and in the control of sublimation rates, in addition to usual physicochemical parameters.
Identifying Martian gully evolution
Authors: Aston A. H. , Conway S. J. , Balme M. R. 
Published: August 2011

Abstract
Martian gullies are small-scale, geologically recent features characterized by the alcove-channel-apron morphology associated with flows with a component of liquid water. Theories advanced to explain Martian gully formation include groundwater processes and melting of near-surface ice due to climate variation. Gullies are often associated with ‘mantling terrain’ that drapes topography at mid to high latitudes and which has been proposed to be ice-rich.
We have morphologically classified Martian gullies into four groupings according to whether they form solely within the mantle (Type A), erode into ‘bedrock’ (Type B), and by how well developed they appear (1 or 2). Orientation, length, geological setting and latitude were also recorded, as well as whether more than one generation of gullies formed on a given slope (labelled ‘reactivated’).
About 25% of gullies form solely within the mantle; these are generally shorter than gullies that erode bedrock and the morphologically simplest gullies (A1) are the shortest. We present latitude and orientation trends for the most recent episode of gully formation. We suggest that this recent activity is probably controlled by either deposition of ice-rich material or degradation of pre-existing ice-rich material.
Blichfeldt-type inequalities and central symmetry
Authors: Henk Martin , Henze Matthias , Wills Jörg M. 
Published: August 2011

Abstract
A classical result of Blichfeldt, from 1921, gives a sharp lower bound on the volume of a convex body K, whose lattice points span the whole space, in terms of the lattice point enumerator . We are interested in a version of this inequality on the set of 0-symmetric convex bodies. Our motivation to study this problem comes from a lack of methods that exploit the symmetry assumption in problems of a similar kind and where 0-symmetry is a natural condition. We report upon sharp Blichfeldt-type inequalities for 0-symmetric lattice polygons, lattice crosspolytopes and lattice zonotopes.
WIT: how to visualise, analyse, and control hollow space formationa
Authors: Michaeli Walter , Gründler Moritz 
Published: August 2011

Abstract
This article deals with hollow space formation that occurs during water injection technique (WIT). The tests presented help improve part quality by providing an in-depth understanding of the influence of polymers and the processes on the propagation of fluid bubbles. Moreover, typical part defects such as double-channel formation or water inclusions in the residual wall are avoided. As their formation has not yet been researched sufficiently, it is not currently possible to design WIT components in relation to the choice of material and residual wall thickness.