Linear Stretch Research Articles

An Approach for Extracting Coral Reef Environs by Interpreting Multi-Dimensional SAR and Multispectral Data

This study explore the SAR coupled with optical data for the delineation of coral reef area in and around the Boat Island of Andaman. The study found that wave interactions with the microwave signal make the spectacular pattern which leads to the delineation of coral area from SAR data. IRS RISAT-1 has the capability to acquire image in different polarization and incident angle, which is explored in this study to segregate coral from the open ocean. K-means unsupervised classification was performed on SAR image and the result shows the high incident angle (43.39\( {}^{\circ} \)) HV polarized image was suitable for delineating the reef edge because of the linear stretch of wave breakage. The low incident angle (27.04\( {}^{\circ} \)) HH polarized image was found to suitable for identifying reef flats in the coastal zone by comparing the wave action in open sea. The protection of Coral reefs requires frequent monitoring. However accessing such area in Andaman Islands is very difficult task due to accessibility, security and climatic concerns. Hence the study proposed to use radar coupled with multispectral image for coral reef mapping in such area. However data selection should be based on study area environments, wave direction and wave height.

Consistent definitions of “Flame Displacement Speed” and “Markstein Length” for premixed flame propagation

The definition of the flame displacement speed (FDS), often used to characterize the dynamical properties of premixed flames, is generally ambiguous because, except for a steadily propagating planar flame, the mass flow rate through the combustion region varies with distance through the flame and one is therefore faced with the difficulty of choosing a proper iso-surface to represent the flame surface. A directly related issue is the determination of the proportionality coefficient in the linear flame speed-flame stretch relation of weakly-stretched flames, known as the Markstein length, which depends strongly on the location inside the flame zone where it is measured or calculated. The objective of the present study is to identify an iso-surface and thereby a definition of the FDS that is well conditioned and less prone to uncertainties, and a consistent and unambiguous expression for the Markstein length. With a selected isotherm to represent the flame surface, the two most common definitions of the FDS are based either on the energy equation with the temperature as the progress variable, or on the kinematic characteristics of the surface (the propagation speed relative to the flow). In this study we examine the spherical flame geometry, a setup that provides an independent determination of the FDS that is not contingent upon an arbitrary selection of the flame surface and thus permits a proper evaluation of the two FDS definitions. A large number of simulations of premixed spherical propane/air flames with equivalence ratio ranging from 0.8 to 1.4 were carried out at various temperatures and pressures using both global single-step and detailed reaction schemes. Outwardly propagating spherical (or cylindrical) flames and inwardly propagating stationary spherical flames were examined. The dependence of the flame speed and flame temperature on stretch, and the corresponding Markstein length were identified for different isotherms selected to represent the flame surface, and the results were carefully compared to the asymptotic theory of weakly-stretched flames. The excellent agreement between theory and simulations provides a clear explanation and quantification of the differences found between the trends in the flame speed-flame stretch relation and the corresponding Markstein lengths, exhibited when the FDS was calculated based on an isotherm in the burned or unburned sides of the flame. We show that the proper isotherm for the evaluation of the FDS which is well-conditioned and properly accounts for the physics must be sufficiently close to the burned side of the flame. This choice is less prone to uncertainty, as the slope of the flame speed-flame stretch relation when reaching the burned side of the flame becomes less dependent on the selected iso-value. On the other hand, the choice of the fresh combustible mixture temperature as a reference location for the calculation of the FDS, and the corresponding unburned Markstein length, is ill conditioned and should be avoided.

High strain extensional rheometry of polymer melts: Revisiting and improving the Meissner design

A new extensional rheometer limited in achievable strain only by sample rupture is presented. The rheometer is based on the Meissner design of two pairs of counter-rotating rollers pulling a sample of fixed length but is small enough to fit inside the oven of a standard rotational rheometer and thus is dubbed the Meissner Extensional Rheometry Accessory (MERA). The true strain rate is calculated by visually accessing the sample during deformation using a high-speed digital camera. Extensional experiments were performed on three materials representing a wide range expected rheological behavior, a styrene-butadiene rubber blend, a linear polystyrene, and a branched low-density polyethylene. The MERA was able to accurately replicate the results of the well-known Sentmanat extensional rheometer (SER) design in terms of onset of strain-hardening and absolute transient extensional viscosity values. However, due to its design, it was possible to achieve homogeneous extensional flow up to real Hencky strains in excess of 8, which corresponds to a linear stretch in excess of 3000. By comparison, the SER is limited to one drum revolution, which corresponds to a Hencky strain of 3.5–4.0 or a maximum linear stretch of approximately 50. Previously the highest Hencky deformations reported in the literature are for the filament stretching extensional rheometer and Rheometric Scientific RME apparatus and in both cases approach 7, which corresponds to a linear stretch of approximately 1000.

Exploration of the Design Principles of a Cell-Penetrating Bicylic Peptide Scaffold

Cell-penetrating peptides (CPPs) possess the capacity to induce cell entry of themselves and attached molecular cargo, either by endocytosis or by direct translocation. Conformational constraints have been described as one means to increase the activity of CPPs, especially for direct crossing of the plasma membrane. Here, we explored the structure-activity relationship of bicyclic peptides for cell entry. These peptides may be considered minimal analogues of naturally occurring oligocyclic peptide toxins and are a promising scaffold for the design of bioactive molecules. Increasing numbers of arginine residues that are primarily contributing to cell-penetrating activity were introduced either into the cycles, or as stretches outside the cycles, at both ends or at one end only. In addition, we probed for the impact of negatively charged residues on activity for both patterns of arginine substitution. Uptake was investigated in HeLa cells by flow cytometry and confocal microscopy. Overall, uptake efficiency showed a positive correlation with the number of arginine residues. The subcellular distribution was indicative of endocytic uptake. One linear stretch of arginines coupled outside the bicycle was as effective in promoting uptake as substituting the same number of arginines inside the bicycles. However, the internally substituted analogues were more sensitive to the presence of negatively charged residues. For a given bicyclic peptide, uptake was more effective than for the linear counterpart. Introduction of histidine and tryptophans further increased uptake efficiency to comparable levels as that of nonaarginine despite the larger size of the bicyclic backbone. The results demonstrate that both arginine clustering and spatial constraints are uptake-promoting structural principles, an observation that gives freedom in the introduction of cell-penetrating capacity to structurally constrained scaffolds.

Configural and featural information in facial-composite images.

Eyewitnesses are often invited to construct a facial composite, an image created of the person they saw commit a crime that is used by law enforcement to locate criminal suspects. In the current paper, the effectiveness of composite images was investigated from traditional feature systems (E-FIT and PRO-fit), where participants (face constructors) selected individual features to build the face, and a more recent holistic system (EvoFIT), where they 'evolved' a composite by repeatedly selecting from arrays of complete faces. Further participants attempted to name these composites when seen as an unaltered image, or when blurred, rotated, linearly stretched or converted to a photographic negative. All of the manipulations tested reduced correct naming of the composites overall except (i) for a low level of blur, for which naming improved for holistic composites but reduced for feature composites, and (ii) for 100% linear stretch, for which a substantial naming advantage was observed. Results also indicated that both featural (facial elements) and configural (feature spacing) information were useful for recognition in both types of composite system, but highly-detailed information was more accurate in the feature-based than in the holistic method. The naming advantage of linear stretch was replicated using a forensically more-practical procedure with observers viewing an unaltered composite sideways. The work is valuable to police practitioners and designers of facial-composite systems.

Geological mapping of the Schuppen belt of north-east India using geospatial technology

A revised geologic map of the Schuppen belt of northeast India has been prepared based on interpretation of digitally enhanced satellite images. The satellite image interpretation is supported by limited field work and existing geologic maps. Available geological maps of this fold thrust belt are discontinuous and multi-scaled. The authors are of multiple opinions regarding the trajectory of formation boundaries and fault contacts. Digital image processing of satellite images and limited field surveys have been used to reinterpret and modify the existing geological maps of this fold thrust belt. Optical data of Landsat Thematic Mapper, Enhanced Thematic Mapper and elevation data of ASTER have been used to prepare this revised geological map. The study area extends from Hajadisa in south to Digboi oilfield in north, bounded by Naga thrust in the west and Disang thrust in the east. PCA, Image fusion, Linear Contrast stretch, Histogram Equalization and Painted relief algorithms have been used for the delineation of major geological lineaments like lithological boundary, thrust and strike slip faults. Digital elevation maps have enabled in the discrimination between thrust contacts and lithological boundaries, with the former being located mostly in the valleys. Textural enhancements of PCA, colour composites and Painted relief algorithm have been used to discriminate between different rock types. Few geological concepts about the terrain have been revisited and modified. It is assumed that this revised map should be of practical use as this terrain promises unexploited hydrocarbon reserves.

Homogenizing Responses to Different Survey Questions on the Same Topic: Proposal of a Scale Homogenization Method Using a Reference Distribution

Survey data are often used for comparison purposes, such as comparisons across nations or comparisons over time. To be effective, this would require equivalent questions and equivalent responses options to the questions. Yet there is a lot of variation in the response scales used, which, for example, differ in the number of response options used and the labeling of these options. This is the case in happiness research, and as a result most of the research data in this field is incomparable. Several methods have been proposed to transform ratings on verbal response scales to a common numerical scale, typically ranging from 0 to 10. In this paper we give an overview of the progress made in those Scale Homogenization methods over time. We describe two early methods: Linear Stretch and the Semantic Judgement of Fixed Word Value Method. Next we discuss the Semantic Judgement of Word Value in Context Method in more detail. Based on these discussions we propose a new Reference Distribution Method. We apply the Semantic Judgement of Word Value in Context and the Reference Distribution Methods to data on happiness in The Netherlands for the years 1989–2009. We show that the Reference Distribution Method produces comparable time series on different questions and that it allows discontinuities in data to be corrected.

Integer points in domains and adiabatic limits

We prove an asymptotic formula for the number of integer points in a family of bounded domains in the Euclidean space with smooth boundary, which remain unchanged along some linear subspace and stretch out in the directions, orthogonal to this subspace. A more precise estimate for the remainder is obtained in the case when the domains are strictly convex. Using these results, we improved the remainder estimate in the adiabatic limit formula (due to the first author) for the eigenvalue distribution function of the Laplace operator associated with a bundle-like metric on a compact manifold equipped with a Riemannian foliation in a particular case when the foliation is a linear foliation on the torus and the metric is the standard Euclidean metric on the torus.

Structural analysis of B-cell epitopes in antibody:protein complexes

The binding of antigens to antibodies is one of the key events in an immune response against foreign molecules and is a critical element of several biomedical applications including vaccines and immunotherapeutics. For development of such applications, the identification of antibody binding sites (B-cell epitopes) is essential. However experimental epitope mapping is highly cost-intensive and computer-aided methods do in general have moderate performance. One major reason for this moderate performance is an incomplete understanding of what characterizes an epitope. To fill this gap, we here developed a novel framework for comparing and superimposing B-cell epitopes and applied it on a dataset of 107 non-similar antigen:antibody structures extracted from the PDB database. With the presented framework, we were able to describe the general B-cell epitope as a flat, oblong, oval shaped volume consisting of predominantly hydrophobic amino acids in the center flanked by charged residues. The average epitope was found to be made up of ∼15 residues with one linear stretch of 5 or more residues constituting more than half of the epitope size. Furthermore, the epitope area is predominantly constrained to a plane above the antibody tip, in which the epitope is orientated in a −30° to 60° angle relative to the light to heavy chain antibody direction. Contrary to previously findings, we did not find a significant deviation between the amino acid composition in epitopes and the composition of equally exposed parts of the antigen surface. Our results, in combination with previously findings, give a detailed picture of the B-cell epitope that may be used in development of improved B-cell prediction methods.

Adaptive Contrast Stretching for Land Observation in Cloudy Low Resolution Satellite Imagery

Although low spatial resolution satellite images like MODIS and GOCI can be important to observe land surface, it is often difficult to visually interpret the imagery because of the low contrast by prevailing cloud covers. We proposed a simple and adaptive stretching algorithm to enhance image contrast over land areas in cloudy images. The proposed method is basically a linear algorithm that stretches only non-cloud pixels. The adaptive linear stretch method uses two values: the low limit (L) from image statistics and upper limit (U) from low boundary value of cloud pixels. The cloud pixel value was automatically determined by pre-developed empirical function for each spectral band. We used MODIS and GOCI images having various types of cloud distributions and coverage. The adaptive contrast stretching method was evaluated by both visual interpretation and statistical distribution of displayed brightness values.

How far do schools of roving herbivores rove? A case study using Scarus rivulatus

Herbivorous reef fish play an important role in shaping ecosystem processes on coral reefs. Often found in schools, Scarus rivulatus, is an abundant herbivorous species on the Great Barrier Reef (GBR), Australia, especially on inshore reefs. Recent evidence has highlighted the limited spatial movements of some herbivorous fishes. However, individuals in schools are thought to be much more mobile. The aim of this study, therefore, was to evaluate the spatial range of schooling S. rivulatus to measure the spatial scale over which they exert their functional role. Furthermore, we assess the influence of the schooling behaviour on their feeding rates and thus their ecological impact. The diurnal movements of S. rivulatus were monitored using acoustic transmitters and a passive acoustic array for up to 7 months in Pioneer Bay, Orpheus Island, GBR. In addition, behavioural observations recorded school size-frequency distributions and feeding rates of S. rivulatus inside and outside foraging schools. Despite schooling, all S. rivulatus were site attached. On average, the maximum potential home range of individuals was 24,440 m2 and ranges overlapped extensively in individuals captured from the same school. School size was highly variable, with a mean school size of 5.7 individuals. Schooling had a significant impact on the functional role of individuals, with feeding rates in schools being two times higher for S. rivulatus and over three times higher for other scarid species. Our results suggest that, despite schooling, individual S. rivulatus only rove over a limited area of reef (occupying a linear stretch of reef, measuring only approximately 250 m for individuals and 220 m for entire schools). Each individual may therefore have little impact on the spatial resilience of coral reefs.

Three-dimensional Numerical Study of the Mixing Behaviour of Twin-screw Elements

Abstract In this work the numerical modeling of the flow inside co-rotating twin-screw extruders is performed and solutions are analyzed to determine the mixing behavior of two screw elements: conveying and mixing elements. The flow around intermeshing screws is computed using an immersed boundary finite element method capable of dealing with complex moving solid boundaries. The flow is considered isothermal and the material behaves as a generalized non-Newtonian fluid. Because the viscosity depends on the shear rate, solutions will be shown for various rotation velocities of the screw. The 3D solutions are then analyzed in order to determine various parameters characterizing the flow mixing such as the residence time and the linear stretch. Residence time distribution inside the twin-screw extruder is first computed by using a particle tracking algorithm based on a fourth order Runge-Kutta method. A large number of particles are tracked inside the extruder and the resulting particle data is used to determine the distribution of the residence time and of the linear stretch. The spatial distribution of the residence time is also computed by solving a transport equation tracking the injection time of the polymer melt. The methodology shows important differences in the mixing behavior of the screw elements considered.

Native Thrombocidin-1 and Unfolded Thrombocidin-1 Exert Antimicrobial Activity via Distinct Structural Elements

Chemokines (chemotactic cytokines) can have direct antimicrobial activity, which is apparently related to the presence of a distinct positively charged patch on the surface. However, chemokines can retain antimicrobial activity upon linearization despite the loss of their positive patch, thus questioning the importance of this patch for activity. Thrombocidin-1 (TC-1) is a microbicidal protein isolated from human blood platelets. TC-1 only differs from the chemokine NAP-2/CXCL7 by a two-amino acid C-terminal deletion, but this truncation is crucial for antimicrobial activity. We assessed the structure-activity relationship for antimicrobial activity of TC-1. Reduction of the charge of the TC-1-positive patch by replacing lysine 17 with alanine reduced the activity against bacteria and almost abolished activity against the yeast Candida albicans. Conversely, augmentation of the positive patch by increasing charge density or size resulted in a 2-3-fold increased activity against Staphylococcus aureus, Escherichia coli, and Bacillus subtilis but did not substantially affect activity against C. albicans. Reduction of TC-1 resulted in loss of the folded conformation, but this disruption of the positive patch did not affect antimicrobial activity. Using overlapping 15-mer synthetic peptides, we demonstrate peptides corresponding to the N-terminal part of TC-1 to have similar antimicrobial activity as intact TC-1. Although we demonstrate that the positive patch is essential for activity of folded TC-1, unfolded TC-1 retained antimicrobial activity despite the absence of a positive patch. This activity is probably exerted by a linear peptide stretch in the N-terminal part of the molecule. We conclude that intact TC-1 and unfolded TC-1 exert antimicrobial activity via distinct structural elements.

Geochemical study of laterites of the Jamnagar district, Gujarat, India: Implications on parent rock, mineralogy and tectonics

The laterite deposits occur in a linear stretch along the northern Arabian Sea coast in the Jamnagar and Porbandar districts of, Gujarat state, India. These deposits are characterised by presence of gibbsite, kaoline, calcite, quartz, anatase, natroalunite, goethite and hematite, and relicts of mafic minerals and plagioclase. On the basis of petro-mineralogy and geochemistry, these deposits are grouped as aluminous laterites (Fe 2O 3 – 1.45–3.84%, Av. 3.13, Al 2O 3 – 39.31–57.24, Av. 45.80) and laterites (Fe 2O 3 – 9.84–32.21, Av. 25.13%, Al 2O 3 – 34.74–49.59, Av. 41.27). The major, trace and REE characteristics of laterites indicate that these were formed in situ by the alteration of parent rocks of trachytic/andesitic composition, and the process of bauxitisation followed the path of destruction of kaolinite and deferruginisation. The correlation patterns of several trace and rare earth elements and their preferential enrichment have indicated that there is an influence of precursor rock on the distribution of trace elements. The Jamnagar laterite deposits occur as capping over the Deccan Trap basaltic lava flows and pyroclasic deposits. Lateritisation prevailed during Palaeocene age when India was separated from the Seychelles and passing over the equator. During this time climate, morphology and drainage conditions were favourable for lateritisation that result in the formation of Jamnagar and other laterite deposits within the Deccan Province. Flood basaltic provinces of Deccan, Columbia, North Australia and Hawaii appear good location for hosting laterite deposits due to their wide areal extent, small geological time span and uniform chemical composition. However, comparison of the major flood basaltic provinces of the world has indicated that their palaeopositions along with palaeoclimate, morphology and drainage are equally important factors for facilitating lateritisation.

Case Scenario: Acute Postoperative Negative Pressure Pulmonary Edema

A 25-yr-old man (weight, 68 kg; height, 183 cm) presentedto the surgery center for excision of back and thigh schwan-nomas on the same day. The patient’s medical history wassignificant only for his history of multiple schwannoma re-sections and a history of smoking one pack of cigarettes perweek for the past 5 yr. He denied previous problems withgeneral anesthesia, and his baseline peripheral oxygen satu-ration was 99% on ambient air.Thepatientwaspremedicatedwith2mgmidazolam,andanesthesia was induced with 250 mg fentanyl, 500 mg thio-pental, and 8 mg vecuronium given for facilitation of tra-cheal intubation. He was atraumatically intubated with a7-mm ID endotracheal tube using a no. 3 Macintosh laryn-goscope (Teleflex Medical, Research Triangle Park, NC) onthe first attempt with direct visualization of the vocal cords.The patient was turned prone, bilateral breath sounds werereconfirmed, and schwannoma excisions were performed ontheleftthighandtheleftflank.Atotalof0.5mghydromor-phone was administered for analgesia. The intraoperativecoursewasunremarkable.Thepatientwashemodynamicallystable with minimal blood loss and was easily ventilated andoxygenated. A total of 500 ml lactated Ringer’s solution wasadministeredduringthe65-minsurgicalprocedure.Thepa-

New approach for dynamic range compression of remote sensing image using wavelet fusion

Most of the recent remote sensing sensors produce higher radiometric resolution than those display devices showing images. Therefore DRC (Dynamic Range Compression) is applied to accommodate original image with large bit-depth to the showing device with less bit-depth. Common stretch methods achieve the DRC with linear line or non-linear curve mapping. The linear stretch loses the details of the highest and lowest luminance area, and the non-linear stretch causes the color distortion issue after the fusion of panchromatic (Pan) and multi-spectrum (MS) image. This paper develops an approach to enhance unapparent features in the Pan image using wavelet fusion method which combine sub-images coming from the same original Pan image. Those sub-image formed by different stretch method for enhancing the radiometric visualization and keeping better correlation with the original color information. According to the experimental result, this approach can apply to not only the airborne but the spaceborne image to produce ideal pan-sharpened product.

Alanine Mutagenesis of the Primary Antigenic Escape Residue Cluster, C1, of Apical Membrane Antigen 1

Antibodies against apical membrane antigen 1 (AMA1) inhibit invasion of Plasmodium merozoites into red cells, and a large number of single nucleotide polymorphisms on AMA1 allow the parasite to escape inhibitory antibodies. The availability of a crystal structure makes it possible to test protein engineering strategies to develop a monovalent broadly reactive vaccine. Previously, we showed that a linear stretch of polymorphic residues (amino acids 187 to 207), localized within the C1 cluster on domain 1, conferred the highest level of escape from inhibitory antibodies, and these were termed antigenic escape residues (AER). Here we test the hypothesis that immunodampening the C1 AER will divert the immune system toward more conserved regions. We substituted seven C1 AER of the FVO strain Plasmodium falciparum AMA1 with alanine residues (ALA). The resulting ALA protein was less immunogenic than the native protein in rabbits. Anti-ALA antibodies contained a higher proportion of cross-reactive domain 2 and domain 3 antibodies and had higher avidity than anti-FVO. No overall enhancement of cross-reactive inhibitory activity was observed when anti-FVO and anti-ALA sera were compared for their ability to inhibit invasion. Alanine mutations at the C1 AER had shifted the immune response toward cross-strain-reactive epitopes that were noninhibitory, refuting the hypothesis but confirming the importance of the C1 cluster as an inhibitory epitope. We further demonstrate that naturally occurring polymorphisms that fall within the C1 cluster can predict escape from cross-strain invasion inhibition, reinforcing the importance of the C1 cluster genotype for antigenic categorization and allelic shift analyses in future phase 2b trials.

Giant-Stroke, Superelastic Carbon Nanotube Aerogel Muscles

Improved electrically powered artificial muscles are needed for generating force, moving objects, and accomplishing work. Carbon nanotube aerogel sheets are the sole component of new artificial muscles that provide giant elongations and elongation rates of 220% and (3.7 x 10(4))% per second, respectively, at operating temperatures from 80 to 1900 kelvin. These solid-state-fabricated sheets are enthalpic rubbers having gaslike density and specific strength in one direction higher than those of steel plate. Actuation decreases nanotube aerogel density and can be permanently frozen for such device applications as transparent electrodes. Poisson's ratios reach 15, a factor of 30 higher than for conventional rubbers. These giant Poisson's ratios explain the observed opposite sign of width and length actuation and result in rare properties: negative linear compressibility and stretch densification.

Initiation of meiotic chromosome synapsis at centromeres in budding yeast

Previous studies of synaptonemal complex assembly in budding yeast have suggested that chromosome synapsis initiates at the sites of crossing over. The data presented here, however, indicate that centromeric regions are preferred sites for synapsis initiation. At early times during meiosis in wild type, the Zip1 protein (a major building block of the synaptonemal complex) localizes specifically to centromeric regions. As synapsis progresses and linear stretches of Zip1 are formed, the majority of stretches are associated with a centromere, as expected if the Zip1 protein present at the centromere polymerized outward along the chromosome arm. In many cases, the centromere is present at one end of a linear stretch, suggesting that synapsis is often unidirectional. Furthermore, the Zip2 protein, a protein that promotes Zip1 polymerization, is often present at the opposite end from the centromere, implying that Zip2 and associated proteins move at the leading edge of Zip1 polymerization. Surprisingly, synapsis initiation at centromeres is independent of the Zip3 protein, which plays a major role in synapsis initiation events at noncentromeric locations. Our data provide evidence for two classes of synapsis initiation events that differ in location, timing, genetic requirements, and relationship to meiotic recombination.

On Pseudorandom Generators with Linear Stretch in NC0

We consider the question of constructing cryptographic pseudorandom generators (PRGs) in NC 0 , namely ones in which each bit of the output depends on just a constant number of input bits. Previous...