How long is a hillslope?

Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope–area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope–area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length–relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridgetop pixel in a DEM, we show that the resulting population of hillslope length–relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient

A corpus-based analysis of the pragmatic marker you get me

status: publishe

Radio Planetary Nebulae in the Small Magellanic Cloud

We present ten new radio continuum (RC) detections at catalogued planetary nebula (PN) positions in the Small Magellanic Cloud (SMC): SMPS6, LIN 41, LIN 142, SMP S13, SMP S14, SMP S16, J18, SMP S18, SMP S19 and SMP S22. Additionally, six SMC radio PNe previously detected, LIN 45, SMP S11, SMPS17, LIN321, LIN339 and SMPS24 are also investigated (re-observed) here making up a population of 16 radio detections of catalogued PNe in the SMC. These 16 radio detections represent ~15 % of the total catalogued PN population in the SMC. We show that six of these objects have characteristics that suggest that they are PN mimics: LIN 41, LIN 45, SMP S11, LIN 142, LIN 321 and LIN 339. We also present our results for the surface brightness - PN radius relation ({\Sigma}-D) of the SMC radio PN population. These are consistent with previous SMC and LMC PN measurements of the ({\Sigma}-D) relation.Comment: Accepted for publication in Astrophysics and Space Scienc

Evaluating LANDSAT-4 MSS and TM data

Interband line pixel misregistrations were determined for the four MSS bands of the Mistassini, Ontario scene and multitemporal registration of LANDSAT-4 products were tested for two different geocoded scenes. Line and pixel misregistrations are tabulated as determined by the manual ground control points and the digital band to band correlation techniques. A method was developed for determining the spectral information content of TM images for forestry applications

CCRS proposal for evaluating LANDSAT-4 MSS and TM data

The measurement of registration errors in LANDSAT MSS data is discussed as well as the development of a revised algorithm for the radiometric calibration of TM data and the production of a geocoded TM image

The effectiveness of parents in promoting the development of road crossing skills in young children

Young children show poor judgment when asked to select a safe place to cross the road, frequently considering dangerous sites to be safe. Correspondingly, child pedestrian accidents are over-represented at such locations. Increasing the child's ability to recognise such dangers is a central challenge for road safety education. Practical training methods have proved effective in improving such judgments but are labour-intensive, time-consuming and therefore difficult to implement on a realistic scale. The study examined the possibility that volunteers from the local community might be capable of using such methods to promote children's pedestrian competence. Sixty children from the Primary 1 (Reception) classes of three Glasgow schools took part. Volunteers were ordinary parents from the same areas. None had 'formal' experience of working with children other than through being parents. Method. Volunteers received experience of training children at courses organised in each school. Children learned in small groups, receiving two sessions of roadside training followed by four on a table-top model. Pre- and post-tests allowed the effectiveness of training to be assessed. Significant improvements relative to controls were found in all children following training. Improvements proved robust and no deterioration was observed two months after the programme ended. Comparison with a previous study in which training was undertaken by highly qualified staff showed that the volunteers were as effective as 'expert' trainers. Parent volunteers can significantly increase the pedestrian competence of children as young as five years. They constitute a most valuable 'resource' in road safety education. The opportunities afforded by involving the local community in educational interventions should be further explored

Tumour markers in breast cancer.

The clinical usefulness of 8 potential tumour markers has been evaluated in 69 patients with Stage I and II breast cancer and 57 patients with Stage III and IV. Serum CEA concentrations were raised in 13% of patients with local and 65% of those with advanced breast cancer. In patients with clinical evidence of progression or regression of tumour, serum CEA levels changed appropriately in 83% of cases. Taking 4 of the markers (carcinoembryonic antigen (CEA), lactalbumin, alpha subunit and haptoglobin) serum concentrations of one or more were raised in 33% of patients with local disease and 81% of those with advanced breast cancer. However, marker concentrations were often only marginally raised, and are unlikely to provide sensitive guide to tumour burden. CEA, lactalbumin and alpha subunit were detectable in 68%, 43% and 40% respectively of extracts of primary breast cancers

Errors in young children's decisions about traffic gaps : experiments with roadside simulations

Young children's vulnerability as pedestrians has often been attributed to deficiencies in their decision making about vehicle approach times. Some studies have found a preponderance o f risky decisions below the age of eight years. In contrast, studies using a closer simulation of road crossing, known as the pretend road, have found a preponderance of overcautious decisions in young children: traffic gaps of adequate size were frequently rejected (missed opportunities). However, the pretend road has potentially distorting characteristics which may account for this divergent pattern of findings. The experiments reported below show that new simulations that eradicate distortions nevertheless validate the pattern of results produced with the pretend road. Differences between adults and young children were pronounced for missed opportunities, but not for risky decisions. Subsidiary analyses suggest that the risky decisions of the youngest children may have arisen through lapses in attention, rather than deficits in timing. These findings run contrary to the view that attributes young children's pedestrian vulnerability to perceptuo-motor deficiency

A developmental and training study of children's ability to find safe routes to cross the road

The sites and routes that children of different ages considered to be safe to cross the road were investigated. In Expt 1, children aged 5, 7, 9 and 11 years were instructed to choose 'the safest' crossing sites and routes to specified destinations. The results showed a gradual developmental shift with safer, more adult-like choices appearing with increasing age. Five and 7 year olds exhibited only a rudimentary selection procedure, choosing the most direct route as safest and showing a marked lack of awareness of the dangers posed by nearby roadside obstacles or other visual restrictions. In a further experiment, 5-year-olds were individually trained in finding safe places to cross. Training took place either in the real road environment or using a tabletop model of a traffic environment. A series of pre-and post-tests enabled the effectiveness of the training to be assessed. Substantial improvements following training were obtained in both groups. No differences were found between the two training methods. Though performance fell somewhat over the two months following training, trained children still outperformed their untrained peers eight months after the programme ended. The implications for road safety education are discussed

Behavioural group training of children to find safe routes to cross the road

Young children show poor judgement when asked to select safe places to cross the road and frequently consider dangerous sites to be safe ones. Thus, a sharp bend, the brow of a hill or positions close to parked cars are considered safe places to cross by most children under 9 years of age. This study examined the effectiveness of two practical training programmes in improving the judgements of 5-year-olds. Children were trained in small groups either in the real road environment or using simulations set up on a table-top model. A series of pre-and post-tests allowed the effectiveness of training to be assessed. Significant improvements relative to controls were found in both groups following training. There were no differences between the two training methods. Improvements were robust and no deterioration was observed two months after the programme ended. However, the benefits of group training were less marked than in an earlier study in which children were trained individually. The implications for road safety education are discussed