Design and Use of Linear Models for Image Motion Analysis

Linear parameterized models of optical flow, particularly affine models, have become widespread in image motion analysis. The linear model coefficients are straightforward to estimate, and they provide reliable estimates of the optical flow of smooth surfaces. Here we explore the use of parameterized motion models that represent much more varied and complex motions. Our goals are threefold: to construct linear bases for complex motion phenomena; to estimate the coefficients of these linear models; and to recognize or classify image motions from the estimated coefficients. We consider two broad classes of motions: i) generic motion features such as motion discontinuities and moving bars; and ii) non-rigid, object-specific, motions such as the motion of human mouths. For motion features we construct a basis of steerable flow fields that approximate the motion features. For object-specific motions we construct basis flow fields from example motions using principal component analysis. In both cases, the model coefficients can be estimated directly from spatiotemporal image derivatives with a robust, multi-resolution scheme. Finally, we show how these model coefficients can be use to detect and recognize specific motions such as occlusion boundaries and facial expressions.     

Global Visions and the Establishment of Theories of the Earth

Abstract During the 17th century, important conventions for the visual representation of the Earth as a whole were established by writers of Theories of the Earth. This essay examines how the emergence of visual representations contributed to the establishment of a new print tradition of multicontextual discourse and critical debate. Four vignettes contrast varying uses of global depictions: the incidental global depictions and mathematical vision of Johannes Kepler; the cosmogonic sections and chemical vision of Robert Fludd; the geogonic sections and mechanical vision of René Descartes; and the global views and classical vision of Thomas Burnet. The continuities of visual conventions and the contrasts of disciplinary perspectives and local contexts observed in these vignettes conforms well to the characterization of Theories of the Earth as an interdisciplinary print tradition.     

Breast disease: dynamic spiral MR imaging

The cochleo- and tonotopic organization of the second auditory area (AII) was investigated in cats anaesthetized with pentobarbital using a combination of macro- and microelectrode recording technique. The results obtained following electrical stimulation of the neural fibres innervating different regions of the organ of Corti indicate the existence of two complete representations of the cochlea in area AII: one in the dorsocaudal portion, the other in its ventrorostral portion. These two cortical representations of the cochlea differ in size and spatial orientation. The dorsocaudal projection area extends over a distance of 2.6-3.2 mm from the basal to the apical focus and is arc-shaped. The spatial orientation of cochlea representation within the dorsocaudal region of AII is similar to that described in AI, in that stimulation of the cochlea base results in maximal responses in the more rostral portion of AII and stimulation of the apex evokes cortical responses more caudally. The ventrorostral region within AII is smaller (1.4-2.5 mm length), and has the opposite cochleotopic orientation (base and apex stimulation represented caudally and rostrally, respectively). In both AII zones, there was a proportionally greater cortical representation of basilar membrane than of middle and apical portions. Although two distinct zones with the overall cochleotopic pattern described above were noted in all cats, their precise size and location considerably varied in different animals. Using microelectrode recordings, a cortical tonotopic organization can be observed that was consistent with and expanded on the earlier cochleotopic data. Within the dorsocaudal region of AII, neurons with higher best frequency responses were located in more rostral regions, while those with lower best frequencies were located caudally. An orderly progression of best frequency responses was noted as serial recordings carried out along the full extent of the representation. Neurons within the ventrorostral region of AII also displayed an orderly progression of best frequencies, but in the opposite direction, with higher best frequencies noted more caudally and lower best frequencies more rostrally.     

Factors associated with suicide attempts among patients with schizophrenia

This study explored the association between psychosocial variables and symptoms among patients with schizophrenia-spectrum disorders who have attempted suicide and those who have not attempted suicide. Of 336 patients with a DSM-III-R diagnosis of schizophrenia or schizoaffective disorder who were consecutively evaluated at a university-affiliated clinical research center, 98, or 29.2 percent, reported one or more suicide attempts. Compared with patients who had not attempted suicide, patients who had made an attempt had a greater number of lifetime depressive episodes, an earlier age of onset of their illness, and an earlier age at first hospitalization.     

SNS Na+ channel expression increases in dorsal root ganglion neurons in the carrageenan inflammatory pain model

In contrast to conventional T cells, natural killer (NK) 1.1+ T cell receptor (TCR)-alpha/beta+ (NK1+T) cells, NK cells, and intestinal intraepithelial lymphocytes (IELs) bearing CD8-alpha/alpha chains constitutively express the interleukin (IL)-2 receptor (R)beta/15Rbeta chain. Recent studies have indicated that IL-2Rbeta/15Rbeta chain is required for the development of these lymphocyte subsets, outlining the importance of IL-15. In this study, we investigated the development of these lymphocyte subsets in interferon regulatory factor 1-deficient (IRF-1-/-) mice. Surprisingly, all of these lymphocyte subsets were severely reduced in IRF-1-/- mice. Within CD8-alpha/alpha+ intestinal IEL subset, TCR-gamma/delta+ cells and TCR-alpha/beta+ cells were equally affected by IRF gene disruption. In contrast to intestinal TCR-gamma/delta+ cells, thymic TCR-gamma/delta+ cells developed normally in IRF-1-/- mice. Northern blot analysis further revealed that the induction of IL-15 messenger RNA was impaired in IRF-1-/- bone marrow cells, and the recovery of these lymphocyte subsets was observed when IRF-1-/- cells were cultured with IL-15 in vitro. These data indicate that IRF-1 regulates IL-15 gene expression, which may control the development of NK1+T cells, NK cells, and CD8-alpha/alpha+ IELs.     

Raised cerebrovascular resistance in idiopathic orthostatic intolerance: evidence for sympathetic vasoconstriction

We examined the gelatinolytic activity in human oral squamous-cell carcinoma tissues in order to evaluate the capability of intravasation and extravasation of cancer cells. By a microdissection-zymography, we demonstrated separately the gelatinolytic activities in cancer cell nests and stroma adjacent to the cancer cells. The gelatinolytic activities, such as pro-matrix metalloproteinase (MMP)9 and active-MMP2 in most of cancer cell nests were much higher than those of normal gingival epithelium. Moreover, the activities of active-MMP2 in cancer cell nests of metastatic cancers were significantly higher than those of non-metastatic cancers (p<0.05). These results suggest that active-MMP2 in cancer cells can be a predictive marker for metastasis formation in oral squamous-cell carcinoma patients.     

Development of a stable episomal shuttle vector for Toxoplasma gondii

The rapid developments in the molecular genetics of Toxoplasma gondii have far reaching implications in treatment and vaccination strategies for this as well as closely related pathogens such as Plasmodium. Although stable transformation of this parasite through homologous and illegitimate genomic integration has provided many of the tools necessary for genetic analysis, subsequent manipulations of the DNA have proven laborious. This report describes the selection and subsequent characterization of a Toxoplasma sequence that permits the episomal maintenance of bacterial plasmids in this parasite. This sequence was isolated from the Toxoplasma genome through selection for episomal stability of a pUC19-based library in the absence of a selectable marker. A 500-base pair fragment was determined to possess the stabilization activity. Transformations of Toxoplasma using vectors possessing this fragment, referred to as EMS (episomal maintenance sequence), demonstrated an elevated stable transformation frequency compared with the vector alone. Mutants deficient in hypoxanthine-xanthine-guanine phosphoribosyltransferase activity were used as a test to see if this gene could be selected from a genomic library using a vector containing the EMS. The success of this test demonstrates the utility of EMS-containing vectors in complementation strategies and the ability of such constructs bearing large fragments of the Toxoplasma genome to be maintained episomally.