Index Trees for Efficient Deformable Shape-based Retrieval

An improved method for deformable shape-based image indexing and retrieval is described. A pre-computed index tree is used to improve the speed of our previously reported on-line model fitting method; simple shape features are used as keys in a pre-generated index tree of model instances. In addition, a coarse to fine indexing scheme is used at different levels of the tree to further improve speed while maintaining matching accuracy. Experimental results show that the speedup is significant, while accuracy of shape-based indexing is maintained. A method for shape population-based retrieval is also described. The method allows query formulation based on the population distributions of shapes in each image. Results of population-based image queries for a database of blood cell micrographs are shown.

Region Segmentation via Deformable Model-Guided Split and Merge

An improved method for deformable shape-based image segmentation is described. Image regions are merged together and/or split apart, based on their agreement with an a priori distribution on the global deformation parameters for a shape template. The quality of a candidate region merging is evaluated by a cost measure that includes: homogeneity of image properties within the combined region, degree of overlap with a deformed shape model, and a deformation likelihood term. Perceptually-motivated criteria are used to determine where/how to split regions, based on the local shape properties of the region group's bounding contour. A globally consistent interpretation is determined in part by the minimum description length principle. Experiments show that the model-based splitting strategy yields a significant improvement in segmention over a method that uses merging alone.

Face Identification by a Cascade of Rejection Classifiers

Nearest neighbor search is commonly employed in face recognition but it does not scale well to large dataset sizes. A strategy to combine rejection classifiers into a cascade for face identification is proposed in this paper. A rejection classifier for a pair of classes is defined to reject at least one of the classes with high confidence. These rejection classifiers are able to share discriminants in feature space and at the same time have high confidence in the rejection decision. In the face identification problem, it is possible that a pair of known individual faces are very dissimilar. It is very unlikely that both of them are close to an unknown face in the feature space. Hence, only one of them needs to be considered. Using a cascade structure of rejection classifiers, the scope of nearest neighbor search can be reduced significantly. Experiments on Face Recognition Grand Challenge (FRGC) version 1 data demonstrate that the proposed method achieves significant speed up and an accuracy comparable with the brute force Nearest Neighbor method. In addition, a graph cut based clustering technique is employed to demonstrate that the pairwise separability of these rejection classifiers is capable of semantic grouping.

Skin and bone: the face in the archaeological imagination

Thirteen unique archaeological countenances from Ireland were produced through the Manchester method of facial reconstruction. Their gaze prompts a space for a broad discourse regarding the face found within human and artefactual remains of Ireland. These faces are reminders of the human element which is at the core of the discipline of archaeology. These re-constructions create a voyeuristic relationship with the past. At once sating a curiosity about the past, facial reconstructions also provide a catharsis to our presently situated selves. As powerful visual documents, archaeological facial reconstructions illustrate re-presentations of the past as well as how the present can be connected to the past. Through engagment with Emmanuel Levinas’s (1906- 1995) main philosophical themes, the presence of the face is examined in a diachronic structure. The ‘starting point’ is the Neolithic period which has been associated with the notion of visuality with a reconstruction from the early Neolithic site of Annagh, Co. Limerick. The following layer of analysis appears with attention to intersubjectivity in the early medieval period with facial reconstructions from Dooey, Co. Donegal and Owenbristy, Co. Galway. Building upon the past concepts, the late medieval period is associated with the notion of alterity and paired with faces from Ballinderry, Co. Kildare and a sample of males from Gallen Priory, Co. Offaly. The final layer of examination culminates with the application of response and respons-ibility to the post-medieval Irish landscape with facial reconstructions from the prison on Spike Island, Co. Cork. These layers of investigation are similar to the stratigraphical composition of both the archaeological landscape and the skeletal/soft tissue landscape of the face. The separation of the neglected phenomenon of the face from the overwhelming embrace of the field of craniometrics is necessary. Through this detachment a new manner in which to discuss the face and its place within the (bio)archaeological record is possible. Encountering the faces seen in mortuary contexts, material culture, and archaeological facial reconstructions, inform and shape the archaeological imagination.

Use of an insulating mask for controlling anisotropy in multilayer electrospun scaffolds for tissue engineering.

Tissue engineering of various musculoskeletal or cardiovascular tissues requires scaffolds with controllable mechanical anisotropy. However, native tissues also exhibit significant inhomogeneity in their mechanical properties, and the principal axes of anisotropy may vary with site or depth from the tissue surface. Thus, techniques to produce multilayered biomaterial scaffolds with controllable anisotropy may provide improved biomimetic properties for functional tissue replacements. In this study, poly(ε-caprolactone) scaffolds were electrospun onto a collecting electrode that was partially covered by rectangular or square shaped insulating masks. The use of a rectangular mask resulted in aligned scaffolds that were significantly stiffer in tension in the axial direction than the transverse direction at 0 strain (22.9 ± 1.3 MPa axial, 16.1 ± 0.9 MPa transverse), and at 0.1 strain (4.8 ± 0.3 MPa axial, 3.5 ± 0.2 MPa transverse). The unaligned scaffolds, produced using a square mask, did not show this anisotropy, with similar stiffness in the axial and transverse directions at 0 strain (19.7 ± 1.4 MPa axial, 20.8 ± 1.3 MPa transverse) and 0.1 strain (4.4 ± 0.2 MPa axial, 4.6 ± 0.3 MPa, transverse). Aligned scaffolds also induced alignment of adipose stem cells near the expected axis on aligned scaffolds (0.015 ± 0.056 rad), while on the unaligned scaffolds, their orientation showed more variation and was not along the expected axis (1.005 ± 0.225 rad). This method provides a novel means of creating multilayered electrospun scaffolds with controlled anisotropy for each layer, potentially providing a means to mimic the complex mechanical properties of various native tissues.

Neural mechanisms of context effects on face recognition: automatic binding and context shift decrements.

Although people do not normally try to remember associations between faces and physical contexts, these associations are established automatically, as indicated by the difficulty of recognizing familiar faces in different contexts ("butcher-on-the-bus" phenomenon). The present fMRI study investigated the automatic binding of faces and scenes. In the face-face (F-F) condition, faces were presented alone during both encoding and retrieval, whereas in the face/scene-face (FS-F) condition, they were presented overlaid on scenes during encoding but alone during retrieval (context change). Although participants were instructed to focus only on the faces during both encoding and retrieval, recognition performance was worse in the FS-F than in the F-F condition ("context shift decrement" [CSD]), confirming automatic face-scene binding during encoding. This binding was mediated by the hippocampus as indicated by greater subsequent memory effects (remembered > forgotten) in this region for the FS-F than the F-F condition. Scene memory was mediated by right parahippocampal cortex, which was reactivated during successful retrieval when the faces were associated with a scene during encoding (FS-F condition). Analyses using the CSD as a regressor yielded a clear hemispheric asymmetry in medial temporal lobe activity during encoding: Left hippocampal and parahippocampal activity was associated with a smaller CSD, indicating more flexible memory representations immune to context changes, whereas right hippocampal/rhinal activity was associated with a larger CSD, indicating less flexible representations sensitive to context change. Taken together, the results clarify the neural mechanisms of context effects on face recognition.

Measurement of intracellular strain on deformable substrates with texture correlation.

Mechanical stimuli are important factors that regulate cell proliferation, survival, metabolism and motility in a variety of cell types. The relationship between mechanical deformation of the extracellular matrix and intracellular deformation of cellular sub-regions and organelles has not been fully elucidated, but may provide new insight into the mechanisms involved in transducing mechanical stimuli to biological responses. In this study, a novel fluorescence microscopy and image analysis method was applied to examine the hypothesis that mechanical strains are fully transferred from a planar, deformable substrate to cytoplasmic and intranuclear regions within attached cells. Intracellular strains were measured in cells derived from the anulus fibrosus of the intervertebral disc when attached to an elastic silicone membrane that was subjected to tensile stretch. Measurements indicated cytoplasmic strains were similar to those of the underlying substrate, with a strain transfer ratio (STR) of 0.79. In contrast, nuclear strains were much smaller than those of the substrate, with an STR of 0.17. These findings are consistent with previous studies indicating nuclear stiffness is significantly greater than cytoplasmic stiffness, as measured using other methods. This study provides a novel method for the study of cellular mechanics, including a new technique for measuring intranuclear deformations, with evidence of differential magnitudes and patterns of strain transferred from the substrate to cell cytoplasm and nucleus.

Shifting ranges and conservation challenges for lemurs in the face of climate change.

Geospatial modeling is one of the most powerful tools available to conservation biologists for estimating current species ranges of Earth's biodiversity. Now, with the advantage of predictive climate models, these methods can be deployed for understanding future impacts on threatened biota. Here, we employ predictive modeling under a conservative estimate of future climate change to examine impacts on the future abundance and geographic distributions of Malagasy lemurs. Using distribution data from the primary literature, we employed ensemble species distribution models and geospatial analyses to predict future changes in species distributions. Current species distribution models (SDMs) were created within the BIOMOD2 framework that capitalizes on ten widely used modeling techniques. Future and current SDMs were then subtracted from each other, and areas of contraction, expansion, and stability were calculated. Model overprediction is a common issue associated Malagasy taxa. Accordingly, we introduce novel methods for incorporating biological data on dispersal potential to better inform the selection of pseudo-absence points. This study predicts that 60% of the 57 species examined will experience a considerable range of reductions in the next seventy years entirely due to future climate change. Of these species, range sizes are predicted to decrease by an average of 59.6%. Nine lemur species (16%) are predicted to expand their ranges, and 13 species (22.8%) distribution sizes were predicted to be stable through time. Species ranges will experience severe shifts, typically contractions, and for the majority of lemur species, geographic distributions will be considerably altered. We identify three areas in dire need of protection, concluding that strategically managed forest corridors must be a key component of lemur and other biodiversity conservation strategies. This recommendation is all the more urgent given that the results presented here do not take into account patterns of ongoing habitat destruction relating to human activities.

Modelling collisions of rail vehicles with deformable objects

This study utilized the latest computing techniques to analyze the driver's cab of a railroad vehicle colliding with deformable objects. It explored the differences between a collision with a deformable object and a collision with a rigid object. It also examined the differences between a collision with a large simple shaped object and a collision with a life-like object. Tools of analysis included vehicle dynamics analysis and finite element analysis.

The New Face of Global Hollywood: Black Hawk Down and the Politics of Meta-Sovereignty

This paper uses Ridley Scott’s 2001 film blockbuster Black Hawk Down to examine the claim that popular film is the ‘newest component of sovereignty’. While the topic of the film – the 1993 UN/US intervention in Somalia – lends itself to straightforward politicisation, this paper is equally interested in the film’s production history and its reception by global audiences. While initial reactions to the film focused on its ideological commitments (e.g. racism, collusion between Hollywood and the Pentagon, post-11 September patriotism), these readings continually posed an imagined ‘America’ against ‘the world’. This paper argues that Black Hawk Down is not about sovereignty as traditionally conceived, that is, about national interest shaping global affairs. Rather, Black Hawk Down articulates, and is articulated by, a new and emerging global order that operates through inclusion, management and flexibility. Drawing on recent theoretical debates over this new logic of rule, this paper illustrates how Black Hawk Down invoked much more diffuse, complex and deterritorialized categories than national sovereignty. In effect, Scott’s film goes beyond traditional notions of sovereignty altogether: its production, signification and reception deconstruct simple notions of ‘America’ and ‘the world’ in favour of what Hardt and Negri call ‘Empire’, what Zizek calls ‘post-politics’, and what we refer to as ‘meta-sovereignty’.

An experiment in group learning technology: evaluating critical thinking in face-to-face and computer-supported seminars

Can learning quality be maintained in the face of increasing class size by the use of Computer Supported Co-operative Learning (CSCL) technologies? In particular, can Computer-Mediated Communication promote critical thinking in addition to surface information transfer? We compared face-to-face seminars with asynchronous computer conferencing in the same Information Management class. From Garrison's theory of critical thinking and Henri's critical reasoning skills, we developed two ways of evaluating critical thinking: a student questionnaire and a content analysis technique. We found evidence for critical thinking in both situations, with some subtle differences in learning style. This paper provides an overview of this work.