Position Of Patch Research Articles

Exoenzyme activities as indicators of dissolved organic matter composition in the hyporheic zone of a floodplain river

Summary1. We measured the hyporheic microbial exoenzyme activities in a floodplain river to determine whether dissolved organic matter (DOM) bioavailability varied with overlying riparian vegetation patch structure or position along flowpaths.2. Particulate organic matter (POM), dissolved organic carbon (DOC), dissolved oxygen (DO), electrical conductivity and temperature were sampled from wells in a riparian terrace on the Queets River, Washington, U.S.A. on 25 March, 15 May, 20 July and 09 October 1999. Dissolved nitrate, ammonium and soluble reactive phosphorus were also collected on 20 July and 09 October 1999. Wells were characterised by their associated overlying vegetation: bare cobble/young alder, mid‐aged alder (8–20 years) and old alder/old‐growth conifer (25 to >100 years). POM was analysed for the ash‐free dry mass and the activities of eight exoenzymes (α‐glucosidase, β‐glucosidase, β ‐N‐acetylglucosaminidase, xylosidase, phosphatase, leucine aminopeptidase, esterase and endopeptidase) using fluorogenic substrates.3. Exoenzyme activities in the Queets River hyporheic zone indicated the presence of an active microbial community metabolising a diverse array of organic molecules. Individual exoenzyme activity (mean ± standard error) ranged from 0.507 ± 0.1547 to 22.8 ± 5.69 μmol MUF (g AFDM)−1 h−1, was highly variable among wells and varied seasonally, with the lowest rates occurring in March. Exoenzyme activities were weakly correlated with DO, DOC and inorganic nutrient concentrations.4. Ratios of leucine aminopeptidase : β‐glucosidase were low in March, May and October and high in July, potentially indicating a switch from polysaccharides to proteins as the dominant component of microbial metabolism.5. Principal components analysis indicated that there were patch effects and that these effects were strongest in the summer.6. DOM degradation patterns did not change systematically along hyporheic flowpaths but varied with overlying forest patch type in the Queets River hyporheic zone, suggesting that additional carbon inputs exist. We hypothesise that the most likely input is the downward movement of DOM from overlying riparian soils. Understanding this movement of DOM from soils to subsurface water is essential for understanding both the hyporheic metabolism and the carbon budget of streams and rivers.

Dynamic Analysis and Active Vibration Control of Flexible Beams Using Piezoelectric Materials: an Optimal Approach

Piezoelectric materials are used in various applications as active vibration control, fault detection in structures and piezoelectric accelerators, therefore, analysis of such materials seems to be necessary in modern mechanical constructions. In this paper, the dynamic analysis of the beam equipped with piezoelectric patches, used as both sensor and actuator, is presented and the beam deflection due to external inputs (force or voltage) is analyzed via modal analysis method. Then, constructing a model for the flexible beam, by the assumed mode approach, an active vibration control is developed by optimal positioning of piezoelectric patches. Simulation results are also presented to illustrate the effectiveness of the methods proposed for dynamic analysis and active vibration control.

Sensors for detecting and logging spatial distribution of urine patches of grazing female sheep and cattle

Urine excreted in patches by grazing livestock accounts for much of the nitrogen (N) loss to the environment in grazing systems. These losses arise mainly through N leaching to ground water and gaseous losses to the atmosphere. Models of grazing systems ideally require data on urination frequency, N load in each urination event and spatial distribution patterns of urine. To date there has been a lack of suitable equipment for obtaining information on urination characteristics of grazing animals. This paper describes a urine sensor that detects and logs each urination event of female sheep and cattle. A thermistor suspended below the vulva continuously measures ambient temperature except when urine passes over it, causing the temperature to rise to near body temperature. Field validation showed 85% and 78% of sensor-detected urination events by sheep and cattle sensors, respectively, were seen by the observer. Some of the urination events identified by the sensor but not seen by the observer were confirmed by video footage. For cattle, only one observed urination event was not detected by the urine sensor, giving a 4% error rate of detection. Daily urination frequencies (ewes: 13–23 events day −1; cows: 11–26 events day −1) were similar to published data for these species. A custom-made GPS unit worn on the rump of the ewe and on the collar of the cow logged animal position continuously so that urine patch position could be determined. Examples of urine distribution patterns by ewes and beef cows in large, hilly paddocks clearly show campsite locations where a disproportionate number of urination events occurred. For sheep, the correlation between time spent in an area and the number of urination events in the same area was r = 0.82, but this correlation was weaker for cattle ( r = 0.54).

A new technique of diaphragmatic patch fixation in extrapleural pneumonectomy

Extrapleural pneumonectomy (EPP) is an established surgical treatment for malignant mesothelioma; this operation is, however, burdened by a high rate of perioperative morbidity, mostly related to the surgical procedure. Diaphragmatic patch dehiscence is a potentially serious complication often related to the difficulty in placement of the fixing stitches, especially in the costo-phrenic angle. We present our experience with the use of titanium-plate support for an easy and safe positioning of the diaphragmatic patch.

Spatial and temporal ecology of Scots pine ectomycorrhizas

Spatial analysis was used to explore the distribution of individual species in an ectomycorrhizal (ECM) fungal community to address: whether mycorrhizas of individual ECM fungal species were patchily distributed, and at what scale; and what the causes of this patchiness might be. Ectomycorrhizas were extracted from spatially explicit samples of the surface organic horizons of a pine plantation. The number of mycorrhizas of each ECM fungal species was recorded using morphotyping combined with internal transcribed spacer (ITS) sequencing. Semivariograms, kriging and cluster analyses were used to determine both the extent and scale of spatial autocorrelation in species abundances, potential interactions between species, and change over time. The mycorrhizas of some, but not all, ECM fungal species were patchily distributed and the size of patches differed between species. The relative abundance of individual ECM fungal species and the position of patches of ectomycorrhizas changed between years. Spatial and temporal analysis revealed a dynamic ECM fungal community with many interspecific interactions taking place, despite the homogeneity of the host community. The spatial pattern of mycorrhizas was influenced by the underlying distribution of fine roots, but local root density was in turn influenced by the presence of specific fungal species.

Local motion effects on form in radial frequency patterns

Sinusoidal modulation of radial speed around a circular path of tangentially oriented Gabor patches results in the percept of modulation of the radius. These patterns have been called motion radial frequency (RF) patterns. Sensitivity to these patterns has been attributed to global summation of local speed by mechanisms, analogous to those proposed to explain sensitivity to spatial RF patterns, which are sensitive to particular radial frequencies of speed modulation. We demonstrate that: Adaptation to spatial RF patterns results in a phase specific after effect in motion RF patterns and vice versa; the rate of change of perceived displacement of a Gabor patch with a moving grating with increasing speed of that grating, is independent of whether the patch is or is not incorporated into a circular path; in the absence of local motion direction cues, global integration across 1, 2 and 3 cycles of motion and spatial RF modulation conforms to a power function with the same index; and finally that the magnitude of the motion position illusion is sufficient and necessary to account for sensitivity to motion RF patterns. We therefore propose that motion RF patterns are analyzed by the same mechanisms responsible for sensitivity to spatial RF patterns using perceived rather than actual local positions of the Gabor patches.

A Theoretical Model for ROP Localisation by Auxin in Arabidopsis Root Hair Cells

BackgroundLocal activation of Rho GTPases is important for many functions including cell polarity, morphology, movement, and growth. Although a number of molecules affecting Rho-of-Plants small GTPase (ROP) signalling are known, it remains unclear how ROP activity becomes spatially organised. Arabidopsis root hair cells produce patches of ROP at consistent and predictable subcellular locations, where root hair growth subsequently occurs.Methodology/Principal FindingsWe present a mathematical model to show how interaction of the plant hormone auxin with ROPs could spontaneously lead to localised patches of active ROP via a Turing or Turing-like mechanism. Our results suggest that correct positioning of the ROP patch depends on the cell length, low diffusion of active ROP, a gradient in auxin concentration, and ROP levels. Our theory provides a unique explanation linking the molecular biology to the root hair phenotypes of multiple mutants and transgenic lines, including OX-ROP, CA-rop, aux1, axr3, tip1, eto1, etr1, and the triple mutant aux1 ein2 gnom eb.Conclusions/SignificanceWe show how interactions between Rho GTPases (in this case ROPs) and regulatory molecules (in this case auxin) could produce characteristic subcellular patterning that subsequently affects cell shape. This has important implications for research on the morphogenesis of plants and other eukaryotes. Our results also illustrate how gradient-regulated Turing systems provide a particularly robust and flexible mechanism for pattern formation.

Hippocampal activation of immediate early genes Zenk and c-Fos in zebra finches ( Taeniopygia guttata) during learning and recall of a spatial memory task

Zebra finches ( Taeniopygia guttata) are able to learn the position of food by orienting on spatial cues in a ‘dry water maze’. In the course of spatial learning, the hippocampus shows high expression of the immediate early genes (IEGs) Zenk and c-Fos, indicating high activation of this area during learning. In contrast, the IEG activity is nearly absent if the birds do not have to rely on spatial cues. In the present experiment it was investigated whether hippocampal activation can also be observed if the learned spatial task is recalled. For this purpose, the hippocampal Zenk and c-Fos activation of birds in an early learning stage was compared with that of others having well reached their maximal performance. The results show that the avian hippocampus is also active during recall of a learned spatial task, but the activation is significantly lower than in animals learning actually. As in previous experiments, hippocampal IEG expression showed strong variation not only in the position of the active patches of neurons, but also in size and cell density. The observed difference contributes to the view that immediate early genes may not be indicators of activation alone, but may be due to a combination of activation and plastic changes.

EC-EGI: enriched complex EGI for 3D shape registration

Extended Gaussian image (EGI) and complex EGI (CEGI) have been widely used as the representation of 3D shapes for shape recognition and pose estimation. In this work, we extend the representations and present a new representation named enriched complex extended Gaussian image (EC-EGI). The representation follows the same framework of EGI and CEGI, which is to represent each surface patch of the target 3D shape as a weight at the associated spot on the surface of the Gaussian sphere. However, while the original CEGI uses a single complex number as the weight, the new representation uses three complex numbers, which are related to the centroid position of the surface patch in 3D. With the inclusion of more information in the new representation, not only could object pose be determined more accurately, but also some key ambiguities of shape representation that CEGI and EGI have also removed. The translation parameters in the pose estimation application could also be determined in a simpler and more accurate way. In addition, the Gaussian sphere partition problem of CEGI is no longer present. Experimental results on synthetic and real image data are shown to illustrate the performance of the proposed representation in pose estimation.

Design of a PZT patch for measuring longitudinal mode impedance in the assessment oftruss structure damage

In the assessment of truss structure damage, the piezoelectric impedance-based techniqueshowed good performance, especially by using the longitudinal wave. However, asatisfactory longitudinal impedance output is not easy to obtain in most practicalapplications. In our previous study, we found that longitudinal vibration modes can begenerated by selecting suitable PZT patches, and used this method for damage assessment.The objective of this paper is to investigate how to design the PZT patch to generate anefficient impedance response in the expected longitudinal modes. First, the influence ofPZT patch design parameters, such as the bonding position and length of the PZT patch,on the piezoelectric impedance response are investigated theoretically. Next, for thepurpose of generating a large longitudinal impedance output at the expected frequency, ascheme for determination of the bonding position and length of the PZT patch isproposed. To validate the proposed method, several examples are demonstratedand discussed. Finally, as an application to use longitudinal modes for damageassessment, crack detection in beams is investigated experimentally and analytically.

Learning-based nonlinear algorithm of face image super-resolution

A super resolution algorithm for single face image based on learned image examples was proposed.The algorithm used patch-based Markov network to express the mechanism of super-resolution processing.After dividing the high-resolution images and the corresponding low-resolution ones into patches,the training dataset was set up.Considering the requirements of Markov network computing and the difference among the images in training dataset,a patch position constraint operation for searching the matched patch and a nonlinear searching algorithm were used.These techniques decreased the complexity of the searching operation and increased the effect of matching.After collecting the matched high-resolution patches,the proposed method directly used them to integrate an output image.Experimental results demonstrate that the approach has better performance and higher efficiency.

Microstrip-Fed Circularly Polarized Square-Ring Patch Antenna for GPS Applications

A novel coupling technique for circularly polarized square-ring patch antenna is developed and discussed. The circular polarization (CP) radiation of the square-ring patch antenna is achieved by a simple microstrip feed line through the coupling of a square patch on the same plane of the antenna. Proper positioning of the coupling square patch excites two orthogonal resonant modes with 90deg phase difference, and a pure circular polarization is obtained. The dielectric material is a square block of ceramic with a permittivity of 58 and that reduces the size of the antenna. The prototype has been designed, fabricated and found to have an impedance bandwidth of 1.1% and a 3-dB axial-ratio bandwidth of about 0.03% at GPS frequency of 1573 MHz. The characteristics of the proposed antenna have been studied by simulation software HFSS and experiments. The measured and simulated results are in good agreement.

실시간 환경에서의 영상조정 및 패치 변경에 의한 축구로봇의 성능개선

본 논문에서는 카메라 렌즈에서 흔히 발생할 수 있는 렌즈의 왜곡에 의한 화상을 보정하고, 로봇 좌표를 인식하기 위해 사용하는 패치의 변경에 의한 로봇의 위치 및 각도오차를 줄여 축구로봇 시스템의 성능 개선에 대한 새로운 방법을 제시한다. 그리고 렌즈의 왜곡 중 기하학적인 왜곡을 보정하여 로봇의 위치오차를 줄여 실시간 환경인 축구로봇 시스템에 적용한다. 로봇의 인식과 로봇의 좌표 및 방향을 판별하기 위하여 사용하는 패치는 그 모양에 따라 로봇이 가지게 되는 위치오차와 각도오차가 발생하게 된다. 본 논문에서는 개선한 로봇패치에 따른 로봇의 위치 및 각도 오차를 줄이는 방법을 제안하고 실험을 통하여 이를 검증하였다.

Analysis on the effective position of a reinforcement patch used as crack arrest for plates with mixed-mode (I/II) cracks

Rectangular patches are usually used as the temporary crack stoppers ahead of the tips of macro cracks. As mixed-mode cracks are usually initiated in engineering structures, the relative position of reinforcement patches to crack tips should be carefully considered. There will be many directions around crack tips for allocating reinforcement patches and the effectiveness of reinforcement patches should be quite dependent on their allocation positions, which can be expressed by the distance between the crack tip and patch, and also the direction of the patch relative to the crack line. The present paper will aim to examine the proper position for allocating the reinforcement patch by comparing the reduction level of the stress intensity factors. Finite element analysis will be conducted for this purpose. The optimum position for allocating the reinforcement patch will be determined, which will be further compared with crack propagation direction determined by strain energy density theory for an elastic cracked body. The conclusion is drawn that the patch with proper stiffness should be allocated in the direction of initial crack propagation near the crack tips. Its effectiveness will not be satisfactory when allocated away from the region.

Neutral models for polygonal landscapes with linear networks

Dynamical mosaic models are very useful in ecology to study the influence of patterns on some ecological processes. Examples of such mosaics are patches of agricultural or forested landscapes. They are often built on the basis of either explicit processes or on neutral approaches using random or almost random element generation. Yet, most of the latter, called neutral landscape models, use a grid-based scheme and simulate pixel mosaics that are autonomous and/or independent. This scheme is not perfectly adapted to anthropogenic patchy landscapes made of contiguous and uniform polygons. Landscape ecology for example explains how a landscape may be seen as a complex mosaic of patches and corridors, with dynamical compositions (the patch attributes) and configurations (their shapes and neighbourhoods). This work presents three neutral landscape models dedicated to manipulations of polygonal patchy mosaic configurations as compared to an observed one. These models have respective advantages that can be summarised in an increasing ability to simulate realistic anthropogenic landscape mosaics. The tessellation approach is simple and rapid, but very much constrained by the patch shapes and positions. The Gibbs algorithm method adapted to landscapes is powerful to manipulate patch positions, with still a weak control on patch shapes. The last method based on a Delaunay triangulation technique offers the opportunity to modulate patch shapes and can still be combined with the Gibbs method to optimise the patch positions. With such neutral landscape models, it is possible to explore ecological hypotheses using a wide range of controlled patchy mosaics.

A future challenge to wheel/rail interaction analysis and design: Predicting worn shapes and resulting damage modes

Wheel/rail interaction remains a systemic problem never to be disassociated with the behavior of the vehicle on the track. The contact patch is often also the interface between the disciplines of vehicle and track design and maintenance. Consequently, any attempt to solve wheel or rail contact problems should always be cognizant of the demands of the total system and the players involved. This keynote presentation reviews current developments in North America impacting contact mechanics. Particular emphasis is placed on current developments in vehicle and track condition measurement and the role of wayside detection in controlling the size and position of the contact patch as well as the forces acting across this patch. The paper closes with a suggested challenge for the future: as flange and gage corner wear are increasingly controlled and as track tolerances improve, the wear of wheel and rail becomes increasingly concentrated on the wheel tread and the rail crown. It is suggested that, as a consequence, wheelset conicity and wheel and rail contact stress changes during the service life of the wheel may become greater than those under high flange wear conditions resulting in reduced vehicle stability and increased wheel and rail fatigue problems during the service life of the wheelset. Consequently, the prediction of wear and material flow patterns on wheel and rail becomes increasingly important in determining system performance as a function of system design parameters such as track gage, wheelset tolerances, and profile shapes for given track topology.

Quasi-Static Tip Positioning of Multi-Segmented IPMC for Micro-Manipulation following Euler—Bernoulli and Pseudo-Rigid Body Model

In this article a kinematic model of multi-segmented ionic polymer metal composite (IPMC) patches has been proposed for micro-manipulation under moisture conditions. Pseudo-rigid body modeling and Euler—Bernoulli approach has been followed to get the end-tip position of the segmented patches. Kinematic modeling is carried out after constituting the homogeneous coordinate transformation considering it as a serial link multi-DOF manipulator. The motion of patches is restricted as planar in 2D. Simulation has been undertaken for single and two patches of IPMC to demonstrate the tip positioning of the segmented IPMC patches for different sequences of input voltage. The experiment is conducted for a single segment of IPMC to validate simulation results. It is observed that experimental results match the simulation results precisely.

From multi-criteria approach to simple protocol: Assessing habitat patches for conservation value using species rarity

We investigated conservation value (CV) related to the quality of spider communities in different non-wooded habitat patches – ranging from arable land to natural grasslands. The study was conducted in two ecologically distinct regions of Hungary: the Hungarian Great Plain and the Buda Hills. We used seven variables to indicate CV which together formed a multi-criteria space of spider community characteristics. These variables were either related to species characters obtained from an extensive background database: abundance and frequency based rarity, specialist status, association to natural habitats; or were calculated for the community at the given patch: species richness, functional diversity and species evenness. Using the variables in an ordination analysis we could establish a gradient of the patches in the multi-criteria space of the spider community characteristics. Position of patches along the first axis of the ordination was taken as the multi-criteria measure of CV. CVs established this way were strongly and positively correlated with an independent botanical CV assessment. We also sought a simpler measure of spider CV by: (a) calculating only one variable out of the seven and using it as a surrogate for the multi-criteria CV measurement; by (b) calculating this variable only for a short time period or (c) for only one spider family. Average abundance based rarity value of the species proved to be the best surrogate of the multi-criteria CV measure for both regions, and it also performed very well when sample size was restricted to two sampling occasions per patch or to a single family. This adds further evidence to, what has been found in other studies, that species rarity is a sensitive and reliable measure of the ecological and conservational status of communities.

A New Coupling Mechanism for Circularly Polarized Annular-Ring Patch Antenna

A novel coupling technique for circularly polarized annular-ring patch antenna is developed and discussed. The circular polarization (CP) radiation of the annular-ring patch antenna is achieved by a simple microstrip feed line through the coupling of a fan-shaped patch on the same plane of the antenna. Proper positioning of the coupling fan-shaped patch excites two orthogonal resonant modes with 90 phase difference, and a pure circular polarization is obtained. The dielectric material is a cylindrical block of ceramic with a permittivity of 25 and that reduces the size of the antenna. The prototype has been designed and fabricated and found to have an impedance bandwidth of 2.3% and a 3 dB axial-ratio bandwidth of about 0.6% at the center frequency of 2700 MHz. The characteristics of the proposed antenna have been by simulation software HFSS and experiment. The measured and simulated results are in good agreement.

Jellyfish patch formation investigated by aerial photography and drifter experiment

Jellyfish patch formation is investigated by conducting a drifter experiment combined with aerial photography of a sustained patch of the moon jellyfish in Hokezu Bay, Japan. Jellyfish patches are aggregations of individuals that are caused by a combination of swimming (active influence) and advection by currents (passive influence). The drifter experiment involved the injection of 49 drifters around a distinct surface patch of jellyfish within an area of approximately 300 m × 300 m. The drifters’ motion, caused only by the passive influence, was recorded in a series of 38 aerial photographs taken over approximately 1 h. The ambient uniform current field larger than the patch scale was estimated from the movement of the centroid position of drifters, while the distribution of horizontal divergence and relative vorticity around the patch was estimated from the time-derivative in areas of triangles formed by the drifters. The centroid positions of both drifters and patches moved stably toward the bay head at different speeds. The difference vector between the patch and drifter centroids was directed to the sun, and was opposite to the ambient current. The distributions of vorticity and divergence around patches exhibited inhomogeneity within the patch scale, and the drifters in this nonuniform current field aggregated near the convergence area within 1 h. The results suggest that horizontal patch formation is predominantly influenced by passive factors at the surface of Hokezu Bay. Furthermore, the upward swimming against downwelling may make sustained patch in surface layer.