Towards a unified visual framework in a binocular active robot vision system

This paper presents the results of an investigation and pilot study into an active binocular vision system that combines binocular vergence, object recognition and attention control in a unified framework. The prototype developed is capable of identifying, targeting, verging on and recognising objects in a cluttered scene without the need for calibration or other knowledge of the camera geometry. This is achieved by implementing all image analysis in a symbolic space without creating explicit pixel-space maps. The system structure is based on the ‘searchlight metaphor’ of biological systems. We present results of an investigation that yield a maximum vergence error of ～6.5 pixels, while ～85% of known objects were recognised in five different cluttered scenes. Finally a ‘stepping-stone’ visual search strategy was demonstrated, taking a total of 40 saccades to find two known objects in the workspace, neither of which appeared simultaneously within the field of view resulting from any individual saccade.     

Wear Performance of Dental Materials: A Comparison of Substructure Ceramics,Veneering Ceramics,and Non‐Precious Alloys

The aim of this in vitro study was to compare the two‐body wear resistance of different dental ceramics and non‐precious alloys. Two‐body wear tests were performed in a chewing simulator with steatite antagonists. A pin‐on‐block design with a vertical load of 50 N for 1.2 × 10⁵ cycles (f = 1.6 Hz; lateral movement: 1 mm, mouth opening: 2 mm) was used for the wear test. Surface roughness R_a (SP6, Perthen‐Feinprüf, G) and wear depth were determined using a 3D‐Profilometer (Laserscan 3D, Willytec, G). Scanning electron microscopy (Quanta FEG 400, FEI, NL) was applied for evaluating wear performance of both, materials and antagonists. Statistics: one‐way ANOVA (α = 0.05). The in vitro wear test showed that the wear performance of dental materials is strongly influenced by the type of material (ceramic, zirconia, or alloy). Zirconia and alloy provided low wear in contrast to glass‐ceramic systems. In contradiction to common expectations, hard zirconia and alloy systems showed even lower antagonistic wear than glass‐ceramics.     

Cerebral mantle thickness: a measurement useful in anatomic diagnosis of fetal ventriculomegaly

The ultrasonographic diagnosis of cerebral ventriculomegaly carries grave implications, in that affected fetuses may suffer abnormal postnatal development or therapeutic abortion. It is important for pathologists to corroborate the clinical diagnosis, but because diagnostic methodologies and criteria differ so radically, this can be problematic. The clinical diagnosis is made primarily by serial ultrasound examinations of the cerebral ventricles, spaces that can be altered postmortem, particularly when the brain is autolysed or deformed artifactually. We therefore sought to learn if examination of tissue, rather than spaces, can identify accurately those fetuses diagnosed with cerebral ventriculomegaly by prenatal ultrasound. The thickness of the cerebral mantle was obtained in 100 control fetuses aged 14 to 26 postmenstrual weeks. Statistical analysis revealed significant correlation of cerebral mantle thickness with crown-rump length, foot length, and head circumference. Twenty fetuses diagnosed with ventriculomegaly showed mantle thicknesses that were less than the control mean. In a few cases, mantle thickness fell between the mean and -1 SD; in several others, thickness was diminished by -1 SD to -2 SD; in one-half of cases, mantle thickness was 2 SDs or more below the expected mean. Head circumference was within 2 SDs of the control mean in most cases, and increased beyond 2 SDs in only two cases. Head circumference is an unreliable indicator of ventriculomegaly in the midgestational fetus. By contrast, cerebral mantle thickness is a simple and useful way of corroborating ultrasonographic diagnoses at autopsy and may also prove useful in clinical settings.     

Structural changes of sarcoplasmic reticulum Ca(2+)-ATPase upon Ca2+ binding studied by simultaneous measurement of infrared absorbance changes and changes of intrinsic protein fluorescence

Ca2+ binding to sarcoplasmic reticulum Ca(2+)-ATPase was investigated by Fourier transform infrared (FTIR) spectroscopy using the photolytic release of Ca2+ from the photolabile Ca2+ chelator 1-(2-nitro-4,5-dimethoxy)-N,N,N',N',- tetrakis[(oxycarbonyl)]methyl-1,2-ethandiamine (DM-nitrophen). IR absorbance changes in 1H2O and 2H2O were detected in the spectral region from 1800 cm-1 to 1200 cm-1, reflecting photolysis of DM-nitrophen and Ca2+ binding to the Ca(2+)-ATPase. As an independent probe for protein conformational changes, intrinsic fluorescence changes upon Ca2+ release were monitored simultaneously to the FTIR measurements. Both the IR absorbance changes and the fluorescence intensity changes correlated well with the Ca2+ binding activity of the ATPase in this specific step. Ca2+ binding caused IR difference bands mainly in the region of amide I absorption of the polypeptide backbone, reflecting conformational changes of the protein. The small amplitude of the signals indicates that only a few residues perform local structural changes such as changes of bond angles or hydrogen bonding. Other absorbance changes appearing above 1700 cm-1 can be assigned to Ca2+ binding to Glu or Asp side chain carboxyl groups and concomitant deprotonation of these residues. This assignment is strengthened by downshifts of these bands by 4 cm-1 to 6 cm-1 upon 1H2O/2H2O exchange. This is in line with results of mutagenesis studies where such residues containing carboxyl groups were associated with the high affinity Ca2+ binding site (Clarke, D.M., Loo, T.W. and MacLennan, D.H. (1990) J. Biol. Chem. 265, 6262-6267).     

Endogenous Modulation of Extracellular Matrix Collagen during Scar Formation after Myocardial Infarction

Myocardial infarction is remains the leading cause of death in developed countries. Recent data show that the composition of the extracellular matrix might differ despite similar heart function and infarction sizes. Because collagen is the main component of the extracellular matrix, we hypothesized that changes in inflammatory cell recruitment influence the synthesis of different collagen subtypes in myofibroblasts, thus changing the composition of the scar. We found that neutrophils sustain the proliferation of fibroblasts, remodeling, differentiation, migration and inflammation, predominantly by IL-1 and PPARγ pathways (n = 3). They also significantly inhibit the mRNA expression of fibrillar collagen, maintaining a reduced stiffness in isolated myofibroblasts (n = 4–5). Reducing the neutrophil infiltration in CCR1^−/− resulted in increased mRNA expression of collagen 11, moderate expression of collagen 19 and low expression of collagen 13 and 26 in the scar 4 weeks post infarction compared with other groups (n = 3). Mononuclear cells increased the synthesis of all collagen subtypes and upregulated the NF-kB, angiotensin II and PPARδ pathways (n = 3). They increased the synthesis of collagen subtypes 1, 3, 5, 16 and 23 but reduced the expression of collagens 5 and 16 (n = 3). CCR2^−/− scar tissue showed higher levels of collagen 13 (n = 3), in association with a significant reduction in stiffness (n = 4–5). Upregulation of the inflammation-related genes in myofibroblasts mostly modulated the fibrillar collagen subtypes, with less effect on the FACIT, network-forming and globular subtypes (n = 3). The upregulation of proliferation and differentiation genes in myofibroblasts seemed to be associated only with the fibrillar collagen subtype, whereas angiogenesis-related genes are associated with fibrillar, network-forming and multiplexin subtypes. In conclusion, although we intend for our findings to deepen the understanding of the mechanism of healing after myocardial infarction and scar formation, the process of collagen synthesis is highly complex, and further intensive investigation is needed to put together all the missing puzzle pieces in this still incipient knowledge process.     

Abnormal microenvironmental signals underlie intestinal aganglionosis in Dominant megacolon mutant mice

Dominant megacolon (Dom) is a mutation in an uncharacterized murine gene which is associated with intestinal aganglionosis and the focal absence of melanocytes in heterozygous animals. The phenotype of Dom/+ heterozygotes is similar to the lethal spotted and piebald lethal mutations, which are due to defects in endothelin-mediated intercellular signals. In this study, the DbetaH-nlacZ transgenic marker for enteric neural crest cells is used to study the distribution of enteric neurons and their precursors in Dom/+ mice and embryos. Vagal neural crest-derived cells in wild-type embryos colonize the gut in a cranial-to-caudal progression. In Dom/+ embryos, colonization was retarded from the earliest stages examined (embryonic Day 11.0), including progression through the small intestine. The early onset of this defect contrasts with impaired neural crest colonization associated with the lethal spotted and piebald lethal mutations which manifest only in the large intestine. Analysis of Dom/+ - +/+ aggregation chimeras indicated that defective colonization is not an autonomous (intrinsic) property of Dom/+ neuroblasts, but like lethal spotted and piebald lethal, the Dominant megacolon mutation directly or indirectly affects microenvironmental signals which influence the migration, proliferation, and/or survival of enteric neural crest cells.     

Anwendung des Nockenverfahrens bei Eigenspannungsmessungen an großen Wellen

Anpassung des Nockenverfahrens an die vorgegebene Aufgabe: Messung der Eigenspannungen in den Randschichten an tangential um-laufenden Bahnen statt an Nocken. Untersuchung der Versuchsparameter, die die an den Bahnen ermittelten Meßergebnisse entscheidend beeinflussen. Überprüfung und Erweiterung der Aussagefähigkeit des Verfahrens. Ermittlung der für Untersuchungen in größerem Umfang geeigneten Versuchsbedingungen. Bestimmung der Eigenspannungen in den Randschichten aus den Meßergebnissen an den Bahnen.     

New four-stitch sleeve anastomosis: an experimental study in rats with reports of clinical use

'The health of its children is the wealth of a nation.' For this reason a lot of time and energy is expended on preventive child health services, but with little evidence of effectiveness and great variation in programmes. Recently much has been done to rectify this. At the forefront of this work has been the multidisciplinary committee chaired by Professor Hall. Its third report, with its concentration on health promotion rather than 'defect detection', will form the basis for all future programmes.