A learning object success story

This paper outlines an approach to designing a course entirely in learning objects. It provides a theoretical basis for the design and then presents evaluation data from a master’s level course using this design. It also describes several re-uses of the learning objects on other courses and in different contexts. Each learning object is conceived as a whole learning experience, thus avoiding many of the problems associated with assembling components of disparate kinds

The varying role of the GP in the pathway between colonoscopy and surgery for colorectal cancer: a retrospective cohort study

Extent: 11p.Objectives: To describe general practitioner (GP) involvement in the treatment referral pathway for colorectal cancer (CRC) patients. Design: A retrospective cohort analysis of linked data. Setting: A population-based sample of CRC patients diagnosed from August 2004 to December 2007 in New South Wales, Australia, using the 45 and Up Study, cancer registry diagnosis records, inpatient hospital records and Medicare claims records. Participants: 407 CRC patients who had a colonoscopy followed by surgery. Primary outcome measures: Patterns of GP consultations between colonoscopy and surgery (ie, between diagnosis and treatment). We investigated whether consulting a GP presurgery was associated with time to surgery, postsurgical GP consultations or rectal cancer cases having surgery in a centre with radiotherapy facilities. Results: Of the 407 patients, 43% (n=175) had at least one GP consultation between colonoscopy and surgery. The median time from colonoscopy to surgery was 27 days for those with an intervening GP consultation and 15 days for those without the consultation. 55% (n=223) had a GP consultation up to 30 days postsurgery; it was more common in cases of patients who consulted a GP presurgery than for those who did not (65% and 47%, respectively, adjusted OR 2.71, 95% CI 1.50 to 4.89, p=0.001). Of the 142 rectal cancer cases, 23% (n=33) had their surgery in a centre with radiotherapy facilities, with no difference between those who did and did not consult a GP presurgery (21% and 25% respectively, adjusted OR 0.84, 95% CI 0.27 to 2.63, p=0.76). Conclusions: Consulting a GP between colonoscopy and surgery was associated with a longer interval between diagnosis and treatment, and with further GP consultations postsurgery, but for rectal cancer cases it was not associated with treatment in a centre with radiotherapy facilities. GPs might require a more defined and systematic approach to CRC management.David Goldsbury, Mark Harris, Shane Pascoe, Michael Barton, Ian Olver, Allan Spigelman, Justin Beilby, Craig Veitch, David Weller, Dianne L O'Connel

Technical innovation changes standard radiographic protocols in veterinary medicine: is it necessary to obtain two dorsoproximal-palmarodistal oblique views of the equine foot when using computerised radiography systems?

Since the 1950s, veterinary practitioners have included two separate dorsoproximal–palmarodistal oblique (DPr–PaDiO) radiographs as part of a standard series of the equine foot. One image is obtained to visualise the distal phalanx and the other to visualise the navicular bone. However, rapid development of computed radiography and digital radiography and their post-processing capabilities could mean that this practice is no longer required. The aim of this study was to determine differences in perceived image quality between DPr–PaDiO radiographs that were acquired with a computerised radiography system with exposures, centring and collimation recommended for the navicular bone versus images acquired for the distal phalanx but were subsequently manipulated post-acquisition to highlight the navicular bone. Thirty images were presented to four clinicians for quality assessment and graded using a 1–3 scale (1=textbook quality, 2=diagnostic quality, 3=non-diagnostic image). No significant difference in diagnostic quality was found between the original navicular bone images and the manipulated distal phalanx images. This finding suggests that a single DPr–PaDiO image of the distal phalanx is sufficient for an equine foot radiographic series, with appropriate post-processing and manipulation. This change in protocol will result in reduced radiographic study time and decreased patient/personnel radiation exposure

Tightness of LP relaxations for almost balanced models

This is the author accepted manuscript. The final version is available from MIcrotome Publishing via http://www.jmlr.org/proceedings/papers/v51/weller16b.html.Linear programming (LP) relaxations are widely used to attempt to identify a most likely configuration of a discrete graphical model. In some cases, the LP relaxation attains an optimum vertex at an integral location and thus guarantees an exact solution to the original optimization problem. When this occurs, we say that the LP relaxation is tight. Here we consider binary pairwise models and derive sufficient conditions for guaranteed tightness of (i) the standard LP relaxation on the local polytope LP+LOC, and (ii) the LP relaxation on the triplet-consistent polytope LP+TRI (the next level in the Sherali-Adams hierarchy). We provide simple new proofs of earlier results and derive significant novel results including that LP+TRI is tight for any model where each block is balanced or almost balanced, and a decomposition theorem that may be used to break apart complex models into smaller pieces. An almost balanced (sub-)model is one that contains no frustrated cycles except through one privileged variable.MR acknowledges support by the UK Engineering and Physical Sciences Research Council (EPSRC) grant EP/L016516/1 for the University of Cambridge Centre for Doctoral Training, the Cambridge Centre for Analysis. DS was supported by NSF CAREER award #1350965

Domain Dynamics of Magnetic Films with Perpendicular Anisotropy

We study the magnetic properties of nanoscale magnetic films with large perpendicular anisotropy comparing polarization microscopy measurements on Co_28Pt_72 alloy samples based on the magneto-optical Kerr effect with Monte Carlo simulations of a corresponding micromagnetic model. We focus on the understanding of the dynamics especially the temperature and field dependence of the magnetisation reversal process. The experimental and simulational results for hysteresis, the reversal mechanism, domain configurations during the reversal, and the time dependence of the magnetisation are in very good qualitative agreement. The results for the field and temperature dependence of the domain wall velocity suggest that for thin films the hysteresis can be described as a depinning transition of the domain walls rounded by thermal activation for finite temperatures.Comment: 7 pages Latex, Postscript figures included, accepted for publication in Phys.Rev.B, also availible at: http://www.thp.Uni-Duisburg.DE/Publikationen/Publist_Us_R.htm

Constraints on Cosmology and Gravity from the Dynamics of Voids

The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content $\Omega_\mathrm{m}=0.281\pm0.031$ in the Universe today, as well as the linear growth rate of structure $f/b=0.417\pm0.089$ at median redshift $\bar{z}=0.57$, where $b$ is the galaxy bias ($68\%$ C.L.). These values originate from a percent-level measurement of the anisotropic distortion in the void-galaxy cross-correlation function, $\varepsilon = 1.003\pm0.012$, and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the low-density regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.Comment: 11 pages, 7 figures. Reflects published version in PRL including Supplemental Materia

Estimation of ocean subsurface thermal structure from surface parameters : a neural network approach

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 31 (2004): L20308, doi:10.1029/2004GL021192.Satellite remote sensing provides diverse and useful ocean surface observations. It is of interest to determine if such surface observations can be used to infer information about the vertical structure of the ocean's interior, like that of temperature profiles. Earlier studies used either sea surface temperature or dynamic height/sea surface height to infer the subsurface temperature profiles. In this study we have used neural network approach to estimate the temperature structure from sea surface temperature, sea surface height, wind stress, net radiation, and net heat flux, available from an Arabian Sea mooring from October 1994 to October 1995, deployed by the Woods Hole Oceanographic Institution. On the average, 50% of the estimations are within an error of ±0.5°C and 90% within ±1.0°C. The average RMS error between the estimated temperature profiles and in situ observations is 0.584°C with a depth-wise average correlation coefficient of 0.92.This work is carried out as a part of the Department of Ocean Development project

Estimation of mixed-layer depth from surface parameters

Author Posting. © Sears Foundation for Marine Research, 2006. This article is posted here by permission of Sears Foundation for Marine Research for personal use, not for redistribution. The definitive version was published in Journal of Marine Research 64 (2006): 745-758, doi:10.1357/002224006779367285.Mixed layer depth (MLD) is an important oceanographic parameter. However, the lack of direct observations of MLD hampers both specification and investigation of its spatial and temporal variability. An important alternative to direct observation would be the ability to estimate MLD from surface parameters easily available from satellites. In this study, we demonstrate estimation of MLD using Artificial Neural Network methods and surface meteorology from a surface mooring in the Arabian Sea. The estimated MLD had a root mean square error of 7.36 m and a coefficient of determination (R2) of 0.94. About 67% (91%) of the estimates lie within ± 5 m (± 10 m) of the MLD determined from temperature sensors on the mooring

Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and hydrostatic equilibrium, with constraints from conservation of energy and pressure balance at the cluster boundary. The resulting properties of the gas for these simulated redshift zero clusters (the temperature distribution, mass-temperature and luminosity-temperature relations, and the gas fraction) are compared with observations in the X-ray of nearby clusters. The observed properties are reproduced only under the assumption that substantial energy injection from non-gravitational sources has occurred. Our model does not specify the source, but star formation and AGN may be capable of providing this energy, which amounts to 3 to 5 x10^{-5} of the rest mass in stars (assuming ten percent of the gas initially in the cluster forms stars). With the method described here it is possible to generate realistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-body simulations, with the distributions of internal halo properties (and their trends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure