An active method of extracting egomotion parameters from optical flow

Instead of the former passive method characterized by a camera fixed on a translating and rotating vehicle, an active method characterized by tracking an object at the center of visual field is proposed. The method extracts egomotion parameters such as the instantaneous direction of translation, the axis of rotation and its angular velocity. A unit spherical surface is used as the projection surface.The theory allows clear vision where needed at the center of the visual field, and simultaneously permits the extraction of egomotion parameters from the periphery of the visual field.     

Quantitative determination of surface concentration of human apolipoprotein H with capillary electrophoresis

The phospholipid monolayer at an air/water interface is widely used to mimic the biological membrane. The dynamic process of the protein or peptide interacting with lipid molecules can be reflected in the change in surface pressure of the monolayer. But the conventional method used to measure the surface pressure change gives results that cannot easily be correlated with the contribution of a single protein molecule. Previously, measuring the surface concentration of the protein molecules at the air/water interface has required the protein to be labeled with radioactivity or fluorescence. Here, a new method using capillary electrophoresis is introduced to measure the surface concentration of the protein. The results show at least two advantages of the new method: The numerical results of protein concentration can be obtained in a more precise and rapid way; and there is no need to label the protein sample or to build a special monolayer setup.     

Age estimation from the auricular surface of the ilium: a revised method

A revised method for estimating adult age at death using the auricular surface of the ilium has been developed. It is based on the existing auricular surface aging method of Lovejoy et al. ([1985] Am. J. Phys. Anthropol. 68:15-28), but the revised technique is easier to apply, and has low levels of inter- and intraobserver error. The new method records age-related stages for different features of the auricular surface, which are then combined to provide a composite score from which an estimate of age at death is obtained. Blind tests of the method were carried out on a known-age skeletal collection from Christ Church, Spitalfields, London. These tests showed that the dispersion of age at death for a given morphological stage was large, particularly after the first decade of adult life. Statistical analysis showed that the age-related changes in auricular surface are not significantly different for males and females. The scores from the revised method have a slightly higher correlation with age than do the Suchey-Brooks pubic symphysis stages. Considering the higher survival rates of the auricular surface compared with the pubic symphysis, this method promises to be useful for biological anthropology and forensic science.     

Oxygen consumption rate of tissue measured by a micropolarographic method

A new method for measuring the oxygen consumption rate of a sheet of homogeneous tissue is described. The method measures, by a Clark-type oxygen electrode without a membrane, the time for the tissue to consume all its dissolved oxygen. The electrode is applied to one surface of the tissue sheet and the other surface is sealed from the atmosphere by a cover slip. The consumption is calculated from an estimate of the oxygen dissolved in the tissue at the moment it is covered and the time for the oxygen tension at one surface to fall to zero. The data also yield the oxygen diffusion coefficient in the oxygen-consuming tissue.     

Evaluation of the contact angle from molecular simulations

An alternative method for determination of the contact angle of droplets at a solid underlay from molecular simulations is proposed. The method is based on a recently developed general method of identification the surface molecules of a molecular system with the interface of an arbitrary shape and on a subsequent parametrisation of the surface of the droplet by a smooth function. The method has been verified first by considering two artificial systems with the exactly known contact angles and then by comparison with literature data for two realistic systems.     

Binding, reconstitution and 2D crystallization of membrane or soluble proteins onto functionalized lipid layer observed in situ by reflected light microscopy

Monolayer of functionalized lipid spread at the air/water interface is used for the structural analysis of soluble and membrane proteins by electron crystallography and single particle analysis. This powerful approach lacks of a method for the screening of the binding of proteins to the surface of the lipid layer. Here, we described an optical method based on the use of reflected light microscopy to image, without the use of any labeling, the lipid layer at the surface of buffers in the Teflon wells used for 2D crystallization. Images revealed that the lipid layer was made of a monolayer coexisting with liposomes or aggregates of lipids floating at the surface. Protein binding led to an increase of the contrast and the decrease of the fluidity of the lipid surface, as demonstrated with the binding of soluble Shiga toxin B subunit, of purple membrane and of solubilized His-BmrA, a bacterial ABC transporter. Moreover the reconstitution of membrane proteins bound to the lipidic surface upon detergent removal can be followed through the appearance of large recognizable domains at the surface. Proteins binding and reconstitution were further confirmed by electron microcopy. Overall, this method provides a quick evaluation of the monolayer trials, a significant reduction in screening by transmission electron microscopy and new insights in the proteins binding and 2D crystallogenesis at the lipid surface.     

New method for estimation of adult skeletal age at death from the morphology of the auricular surface of the ilium

A new method for estimating skeletal age at death from the morphology of the auricular surface of the ilium is presented. It uses a multiple regression analysis with dummy variables, and is based on the examination of 700 modern Japanese skeletal remains with age records. The observer using this method needs only to check for the presence or absence of nine (for a male) or seven (for a female) features on the auricular surface and to select the parameter estimates of each feature, calculated by multiple regression analysis with dummy variables. The observer can obtain an estimated age from the sum of parameter estimates. It is shown that a fine granular texture of the auricular surface is typical of younger individuals, whereas a heavily porous texture is characteristic of older individuals, and that both of these features are very useful for estimating age. Our method is shown here to be more accurate than other methods, especially in the older age ranges. Since the auricular surface allows more expedient observations than other parts of the skeleton, this new method can be expected to improve the overall accuracy of estimating skeletal age at death.     

光闪烁方法测算区域蒸散研究进展

蒸散是土壤-植物-大气连续体(SPAC)水热运移的一个重要环节,是全球水量平衡的重要组成,一直是气象学、水文学、地理学及生态学等相关学科重要的研究主题。区域尺度地表蒸散的时空变化过程十分复杂。迄今为止,在像元尺度水平上,特别在非均匀下垫面和地形起伏条件下,有代表性的进行地表蒸散的观测仍然十分困难。虽然遥感方法可获得区域尺度水平蒸散,但其主要根据经验或半经验模型对区域蒸散进行估算,模型选用的参数以及结果还需地面实测数据进行改进、优化,如何获得与遥感尺度相应的地面蒸散实测数据成为模型验证的重点和难点,光闪烁方法的出现为上述问题的解决带来了希望。光闪烁方法能够适应复杂下垫面,测量结果准确且具有时空平均等优点,成为测量区域蒸散的有效方法、验证遥感模型结果的最佳手段。从理论原理、计算方法、主要应用情况等方面,概述了光闪烁方法观测区域蒸散研究进展,指出了影响测算精度的不确定性因素,并提出了研究展望,旨在进一步推动该方法在区域蒸散观测研究中的应用,促进相关学科的发展。     

Measurement of protein surface shape by solid angles

A method for measuring the gross shape of local regions of protein surface is presented and applied to an examination of three proteins. Any point on the protein surface can be assigned a number that measures the degree of convexity or concavity of the surface in the vicinity of the point. This number is computed by centring a sphere at that point and measuring how much of the sphere lies inside the protein. The sphere radius is a parameter chosen according to the scale of the features that are being analysed. The amount of sphere intersecting the protein is interpreted as a solid angle, denoted omega. Three proteins are analysed by this method: lysozyme, Superoxide dismutase and chymotrypsin. The resulting omega values are used to colour code the protein surfaces displayed on a colour raster graphics terminal. The method can be seen to reliably identify protrusions and depressions. The difficulty of developing a generally useful method for measuring protein surface shape is discussed. Possible applications of the solid-angle method include the analysis of shape complementarity at protein interfaces, the development of computer algorithms for predicting complexes between proteins, or between proteins and ligands, the identification of homologous epitopes on different proteins that might be immunologically crossreactive, and the determination of correlations between surface geometry and chemical properties.     

Airway surface liquid depth imaged by surface laser reflectance microscopy

The thin layer of liquid at the surface of airway epithelium, the airway surface liquid (ASL), is important in normal airway physiology and in the pathophysiology of cystic fibrosis. At present, the best method to measure ASL depth involves scanning confocal microscopy after staining with an aqueous-phase fluorescent dye. We describe here a simple, noninvasive imaging method to measure ASL depth by reflectance imaging of an epithelial mucosa in which the surface is illuminated at a 45-degree angle by an elongated 13-µm wide rectangular beam produced by a 670-nm micro-focus laser. The principle of the method is that air–liquid, liquid–liquid, and liquid–cell interfaces produce distinct specular or diffuse reflections that can be imaged to give a micron-resolution replica of the mucosal surface. The method was validated using fluid layers of specified thicknesses and applied to measure ASL depth in cell cultures and ex vivo fragments of pig trachea. In addition, the method was adapted to measure transepithelial fluid transport from the dynamics of fluid layer depth. Compared with confocal imaging, ASL depth measurement by surface laser reflectance microscopy does not require dye staining or costly instrumentation, and can potentially be adapted for in vivo measurements using fiberoptics.     

Surface kinetic test method for determining rate of kill by an antimicrobial solid.

An antimicrobial-surface kinetic test which maximizes probability of cell-to-surface contact has been developed. The measurement of rate of kill by a nonleaching antimicrobial surface is based on the number of surviving bacterial cells at specific times of exposure to various amounts of total treated surface area of test substrate. This method gives information for direct comparison of rate of kill for a variety of antimicrobial surfaces in terms of rate of kill per square centimeter of surface area. Data obtained by this method can also give valuable dose response application information as an indication of the exponential efficiency of concentration in terms of treated surface area.     

Surface kinetic test method for determining rate of kill by an antimicrobial solid.

An antimicrobial-surface kinetic test which maximizes probability of cell-to-surface contact has been developed. The measurement of rate of kill by a nonleaching antimicrobial surface is based on the number of surviving bacterial cells at specific times of exposure to various amounts of total treated surface area of test substrate. This method gives information for direct comparison of rate of kill for a variety of antimicrobial surfaces in terms of rate of kill per square centimeter of surface area. Data obtained by this method can also give valuable dose response application information as an indication of the exponential efficiency of concentration in terms of treated surface area.     

A new method for the representation of articular surfaces using the influence surface theory of plates

The traditional approach to the representation of an articular surface is by using piecewise polynomial functions with a limited continuity to fit the surface from ordered data points. In this study, we introduce a new method, which is based on the influence surface theory of plates, for the representation of articular surfaces. The most significant advantage of this method is that it can effectively represent an articular surface from non-ordered data points. The effectiveness of the present method was shown by reconstruction of a human femoral surface and a mathematical cone.     

Lateral diffusion of cholesterol in monolayers.

The surface diffusion coefficient of cholesterol in cholesterol monolayers has been measured as a function of cholesterol surface concentration. Two different radiochemical methods, one integral and the other differential, were developed which gave comparable results. In the integral method two cholesterol monolayers, one of which is radioactive, are isolated on inert hydrophilic supports and then brought into contact. After some time the supports are separated and the radioactivity of the supports is measured. The differential method is an autoradiographic experiment. Two cholesterol monolayers, one of which is radioactive, are separated by means of a thin barrier. Upon removal of the barrier and at later times, an autoradiographic plate is brought to within a fraction of a mm from the aqueous surface and exposed. The plates are developed and analysed. The data show that the cholesterol surface diffusion coefficient in the dilute monolayers is approximately 10(-6)cm2/s and is nearly independent of surface concentration up to a concentration corresponding to an area of 40 A2/molecule. As the monolayer becomes compressed beyond this surface concentration, the diffusion coefficient decreases ubruptly with the deeply decreasing surface tension to about 10(-7) cm2/s, when a fully condensed surface layer of 38 A2/molecule is reached. This diffusion coefficient is of the same order of magnitude as the diffusion coefficients measured in lipid bilayers and in membranes.     

The transmembrane proteins in the plasma membrane of normal human erythrocytes. Evaluation employing lactoperoxidase and proteases.

The molecular architecture of the human erythrocyte membrane has been probed using lactoperoxidase-catalyzed iodination in conjunction with Pronase hydrolysis. Resealed, hemoglobin-free ghosts were labeled at the cytoplasmic surface and the external membrane surface was subsequently digested with Pronase. Changes in size of the components labeled at the cytoplasmic surface were readily detected by sodium dodecyl sulfate gel electrophoresis. The protein 3 molecular weight class labeled at the cytoplasmic surface was extensively hydrolyzed at the external surface to produce a major 65000 molecular weight fragment and a minor 45000 molecular weight fragment. When resealed membranes were labeled on the external surface the same 65000 molecular weight labeled component is produced. These results unequivocally demonstrate that the same polypeptides in the protein 3 molecular weight class that can be labeled by lactoperoxidase at the cytoplasmic membrane surface are digested by Pronase at the external surface and are, therefore, transmembrane components. Where it is possible to label one surface of a membrane with lactoperoxidase and reseal the membrane this procedure represents an alternate method for establishing transmembrane configuration of membrane proteins.     

Surface activation of dyed fabric for cellulase treatment

Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry.     

Hydrophobicity at the surface of proteins

A new method is presented to quantitatively estimate and graphically display the propensity of nonpolar groups to bind at the surface of proteins. It is based on the calculation of the binding energy, i.e., van der Waals interaction plus protein electrostatic desolvation, of a nonpolar probe sphere rolled over the protein surface, and on the color coding of this quantity on a smooth molecular surface (hydrophobicity map). The method is validated on ten protein-ligand complexes and is shown to distinguish precisely where polar and nonpolar groups preferentially bind. Comparisons with existing approaches, like the display of the electrostatic potential or the curvature, illustrate the advantages and the better predictive power of the present method. Hydrophobicity maps will play an important role in the characterization of binding sites for the large number of proteins emerging from the genome projects and structure modeling approaches.     

Detecting surface‐feeding behavior by rorqual whales in accelerometer data

The movement of marine animals feeding at the sea surface is restricted by wave drag and a reduction in propulsive efficiency. Many rorqual whale species lunge feed at the surface, yet existing methodologies for detecting lunges in accelerometer data have not been applied to surface‐feeding behavior. Our study aimed to develop a method to detect surface‐feeding behavior in accelerometer data and in doing so, determine whether wave drag influences the detection of surface‐feeding behavior. A new acceleration parameter is described that considers the forward acceleration of the animal relative to its pitch. The new parameter, along with information on the deceleration and pitch angle, was then used in an automatic lunge detecting algorithm followed by a visual classification method that detected approximately 70% of the lunges observed during focal follow sampling. The forward acceleration of lunges decreased significantly with increasing proximity to the surface. This lower acceleration at the surface may influence the ability to detect lunge feeding behavior close to the surface. Future research should attempt to determine the cause of this relationship, which may be the influence of changes in the forces acting on the whale or behavioral flexibility by the whale.     

A Mathematical-Physical Model of the Genesis of the Electrocardiogram

A fundamental problem of cardiac electrophysiology is that of relating quantitatively the electrical activity within the heart to the complete timevarying potential distribution at the body surface. A new numerical method is described for the calculation of the surface potential on an irregularly shaped closed external surface due to an arbitrary source distribution in a medium containing regions of different conductivity, subject to the appropriate boundary conditions. The method is intended to provide an exact theoretical analysis of the experimental data acquired by A. M. Scher and others who have been mapping the pathways of ventricular depolarization in dogs and other animals. In anticipation of the above research program, a number of exploratory computations are reported. For example, the surface potential distribution has been calculated for a cylinder of human torso cross-section with a hemispherical dipole layer current source in approximate heart position and orientation and containing “lungs” of conductivity different from that of the surrounding medium. Under certain conditions, when lung-like inhomogeneities are introduced, a simple dipole source can generate a potential distribution having the multiple maxima and minima characteristic of higher multipole sources.     

Evaluation of the relative cell surface charge by using microbial adhesion to hydrocarbon

A simple and rapid method, Microbial adhesion to hexadecane, for estimating the cell surface charge is proposed. This method is based on the determination of cell affinity to hexadecane at low ionic strength and at high ionic strength. The difference between these two affinities can provide the relative cell surface charge. The application of this method for Staphylococcus aureus and Escherichia coli show that the profile of surface charge evolution as a function of pH was similar to these obtained by microelectrophoresis method.