13,978 research outputs found
International Students' Cross-cultural Experiences Of Learning
To have an open mind is more important than learning; and we can have an open
mind, not by cramming it full of information, but by being aware of our own
thoughts and feelings, by carefully observing ourselves and the influences about
us, by listening to others, by watching the rich and the poor, the powerful and the
lowly. Wisdom does not come through fear and oppression, but through the
observation and understanding of everyday incidents in human relationship
Deep optical imaging of the field of PC1643+4631A&B, II: Estimating the colours and redshifts of faint galaxies
In an investigation of the cause of the cosmic microwave background decrement
in the field of the z = 3.8 quasar pair PC1643+4631, we have carried out a
study to photometrically estimate the redshifts of galaxies in deep
multi-colour optical images of the field taken with the WHT. To examine the
possibility that a massive cluster of galaxies lies in the field, we have
attempted to recover simulated galaxies with intrinsic colours matching those
of the model galaxies used in the photometric redshift estimation. We find that
when such model galaxies are added to our images, there is considerable scatter
of the recovered galaxy redshifts away from the model value; this scatter is
larger than that expected from photometric errors and is the result of
confusion, simply due to ground-based seeing, between objects in the field. We
have also compared the likely efficiency of the photometric redshift technique
against the colour criteria used to select z>3 galaxies via the strong colour
signature of the Lyman-limit break. We find that these techniques may
significantly underestimate the true surface density of z>3, due to confusion
between the high-redshift galaxies and other objects near the line of sight. We
argue that the actual surface density of z=3 galaxies may be as much as 6 times
greater than that estimated by previous ground-based studies, and note that
this conclusion is consistent with the surface density of high-redshift objects
found in the HDF. Finally, we conclude that all ground-based deep field surveys
are inevitably affected by confusion, and note that reducing the effective
seeing in ground-based images will be of paramount importance in observing the
distant universe.Comment: 18 pages, 60 figures, submitted to MNRAS, 2 large figure avaliable at
ftp://ftp.mrao.cam.ac.uk:/pub/PC1643/paper2.figure50.eps and
ftp://ftp.mrao.cam.ac.uk:/pub/PC1643/paper2.figure51.ep
The biomechanical role of the chondrocranium and sutures in a lizard cranium
The role of soft tissues in skull biomechanics remains poorly understood. Not least, the chondrocranium, the portion of the braincase which persists as cartilage with varying degrees of mineralization. It also remains commonplace to overlook the biomechanical role of sutures despite evidence that they alter strain distribution. Here, we examine the role of both the sutures and the chondrocranium in the South American tegu lizard Salvator merianae. We use multi-body dynamics analysis (MDA) to provide realistic loading conditions for anterior and posterior unilateral biting and a detailed finite element model to examine strain magnitude and distribution. We find that strains within the chondrocraniumare greatest during anterior biting and are primarily tensile; also that strain within the cranium is not greatly reduced by the presence of the chondrocraniumunless it is given the same material properties as bone. This result contradicts previous suggestions that the anterior portion (the nasal septum) acts as a supporting structure. Inclusion of sutures to the cranium model not only increases overall strain magnitudes but also leads to a more complex distribution of tension and compression rather than that of a beam under sagittal bending
Exploiting context information to aid landmark detection in SenseCam images
In this paper, we describe an approach designed to exploit
context information in order to aid the detection of landmark images from a large collection of photographs. The
photographs were generated using Microsoft’s SenseCam, a
device designed to passively record a visual diary and cover
a typical day of the user wearing the camera. The proliferation of digital photos along with the associated problems of managing and organising these collections provide the background motivation for this work. We believe more ubiquitious cameras, such as SenseCam, will become the norm in the future and the management of the volume of data generated by such devices is a key issue. The goal of the work reported here is to use context information to assist in the detection of landmark images or sequences of images from the thousands of photos taken daily by SenseCam. We will achieve this by analysing the images using low-level MPEG-7 features along with metadata provided by SenseCam, followed by simple clustering to identify the landmark images
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