Small Size Objects Research Articles

Sci—Wed PM: Delivery—09: Automatic Contrast Enhancement on Electronic Portal Images Based on Human Visual System Properties

Image Guided Radiation Therapy (IGRT) is one of the most efficient ways to treat prostate cancer. It is well‐known that Electronic Portal Images (EPI) acquired prior to the radiation therapy are of poor quality due to the low radiation dose. Several image parameters need to be manually adjusted in order to be able to visualize and localize the fiducial markers (FMs) seeds at the beginning of each day of treatment. This localization process is essential for the proper alignment of the patient. In this paper, we propose a novel technique for automatic image enhancement. There are many challenges involved in the automation of the image enhancement for FM seed detection. An automated enhancement algorithm is image and noise dependant. The level of noise in an input image and global image properties such as average contrast and intensity vary significantly between different patients and even for the same patient between different image acquisition sessions. Moreover, the small size of the targets (the FM seeds) makes it very difficult to distinguish them from noise, and hence to enhance them. Our approach addresses these challenges by using a contrast enhancement scheme based on properties of the human visual system (HVS). The rationale behind considering this approach lies in the ability of the HVS to adapt to detect objects of small size under low contrast and noise conditions. Our main contribution lies in the automatic set‐up of the parameters based upon a maxima search over a contrast metric.

PSICIC: Noise and Asymmetry in Bacterial Division Revealed by Computational Image Analysis at Sub-Pixel Resolution

Live-cell imaging by light microscopy has demonstrated that all cells are spatially and temporally organized. Quantitative, computational image analysis is an important part of cellular imaging, providing both enriched information about individual cell properties and the ability to analyze large datasets. However, such studies are often limited by the small size and variable shape of objects of interest. Here, we address two outstanding problems in bacterial cell division by developing a generally applicable, standardized, and modular software suite termed Projected System of Internal Coordinates from Interpolated Contours (PSICIC) that solves common problems in image quantitation. PSICIC implements interpolated-contour analysis for accurate and precise determination of cell borders and automatically generates internal coordinate systems that are superimposable regardless of cell geometry. We have used PSICIC to establish that the cell-fate determinant, SpoIIE, is asymmetrically localized during Bacillus subtilis sporulation, thereby demonstrating the ability of PSICIC to discern protein localization features at sub-pixel scales. We also used PSICIC to examine the accuracy of cell division in Esherichia coli and found a new role for the Min system in regulating division-site placement throughout the cell length, but only prior to the initiation of cell constriction. These results extend our understanding of the regulation of both asymmetry and accuracy in bacterial division while demonstrating the general applicability of PSICIC as a computational approach for quantitative, high-throughput analysis of cellular images.

10.1007/s11700-008-1004-2

The methods of phase composition diagnostics of materials by Auger spectra, developed in IMT RAS over a number of years, are presented. Examples of their use are generally in the determination of phase depth profiles. However, the considered methods can be also used for the composition diagnostics of small size objects (nanostructures) under conditions of significant noisiness of the Auger spectra and when the studied objects probably leave an analyzed region.

Ergonomic study of a vertical rope-pulling task from a scaffolding

The purpose of this study is to explore and assess manual material handling problems involving a vertical rope-pulling task from a scaffold (VRPS). Twenty-five young male Chinese subjects were recruited to participate in this study. The psychophysical method was used to investigate the effects of the rope material (nylon and hemp), rope diameter (6/8″ and 4/8″), object size (bucket diameter 28 cm and 36 cm), operating with and without gloves on the maximum acceptable rope-pulling weight (MAWR), rating of perceived exertion (RPE) and heart rate, respectively. The results showed that the maximum acceptable rope-pulling weights were significantly affected by the rope material, rope diameter, object size and wearing or not wearing gloves. The MAWR for the hemp rope, coarse rope, small object size and without gloves was significantly greater than that for the nylon rope, fine rope, large object size and with gloves, respectively. However, the effect of the rope material, rope diameter, object size and with and without gloves on heart rate was not significant. The mean RPE response was significantly influenced by the rope material, object size and wearing or not wearing gloves. The most stressed body parts were the arms, fingers and wrists. The interaction effect between the rope material and wearing or not wearing gloves was significant. Generally, the VRPS for workers using hemp rope without gloves or using nylon rope without gloves was better than that for the other combinations.

Methods of Auger signal processing in the quantitative diagnostics of the composition of nanostructures

The methods of the processing of a sequence of noisy Auger spectra obtained in the diagnostics of the composition of small-size objects (nanostructures) under conditions where they leave an analyzed region either due to ion sputtering or because of the drift of a sample holder are considered. It is shown that the preliminary specification of the projection directions of the original multidimensional data allows us to overcome the instability arising in numerical algorithms of statistical methods due to an experimental error and to separate sets of Auger spectra corresponding to different compositions.

Cortical responses to object size‐dependent spectral interference patterns in echolocating bats

Echolocating bats can recognize 3-D objects exclusively through the analysis of the reflections of their ultrasonic emissions. For objects of small size, the spectral interference pattern of the acoustic echoes encodes information about the structure of an object. For some naturally occurring objects such as, e.g., flowers, the interference pattern as well as the echo amplitude can regularly change with the object's size, and bats should be able to compensate for both of these changes for reliable, size-invariant object recognition. In this study, electrophysiological responses of units in the auditory cortex of the bat Phyllostomus discolor were investigated using extracellular recording techniques. Acoustical stimuli consisted of echoes of virtual two-front objects that varied in size. Thus, the echoes changed systematically in amplitude and spectral envelope pattern. Whereas 30% of units simply encoded echo loudness, a considerable number of units (20%) encoded a specific spectral envelope shape independent of stimulus amplitude. In addition, a small number of cortical units (3%) were found that showed response-invariance for a covariation of echo amplitude and echo spectral envelope. The response of these two classes of units could not be simply predicted from the excitatory frequency response areas. The results show that units in the bat auditory cortex exist that might serve for the recognition of characteristic object-specific spectral echo patterns created by, e.g., flowers or other objects independent of object size or echo amplitude.

Dynamic characterization of MEMS diaphragm using time averaged in-line digital holography

In this paper dynamic characterization of a MEMS diaphragm is investigated using lens-less time averaged in-line digital holography. The analysis and capability of the numerically reconstructed amplitude and phase information from in-line time averaged holograms as applied to MEMS vibration are presented. Particularly the effect of mean static state on the phase in time averaged digital holography is explored. A novel double exposure method is also demonstrated using a diverging object wave suitable for dynamic characterization of small size objects. A phase jump in the static deformation fringes in the vibrating regions is observed and described and can be used for precise analysis of vibration mode shape under simultaneous presence of mean static deformation. A simple and robust tool for dynamic optical metrology of MEMS devices and micro-objects using time averaged in-line digital holography is thus proposed.

Exploring Signatures of Different Physical Processes for Fusion With Scattering Muon Tomography

The success of scattering muon tomography has prompted us to explore cosmic ray flux attenuation, electro-magnetic shower induction, and muonic X-ray emission as additional means for the non-destructive assay of small and medium size objects. We report on the value of the signatures of these processes as an adjunct to multiple scattering muon tomography. We discuss our experiments and the Monte-Carlo calculations of these processes, the type of information that can be drawn from their signatures, the cost and the value of this information. We discuss the general requirements for detector systems to make use of cosmic ray flux attenuation, induction of electro-magnetic showers, and muonic X-rays in muon tomography. We find that the attenuation of the cosmic ray flux allows for the inference of the density distribution for objects of automobile size and smaller with exposure times of order a few minutes. Our preliminary experiments and calculations have shown that using muonic X-rays to identify composition is exceedingly difficult, requiring months of exposure. Our experiments are not yet sensitive enough to detect muonic x-rays at the rates expected from previous accelerator experiments

Development of a single-master multi-slave tele-micromanipulation system

This paper proposes the development of a human–robot cooperative tele-micromanipulation system through a network. We have developed a novel single-master (PHANToM haptic device) multi-slave (6-d.o.f. parallel manipulator) scaled tele-micromanipulation system which enables human operators to perform meso or small-size object manipulation such as assembly or manufacturing with sufficient telepresence. It is expected to improve the human's operability and the overall dexterity of conventional tele-micromanipulation systems. To overcome the problems of the multiple parallel mechanism manipulator, virtual kinematic mapping is considered, based on the manipulability analysis of the workspace. The pick-and-place experiment results prove the validity of the developed single-master multi-slave system.

Layer or Strip Resistance Measurement by Electron Beam Induced Current Technique in a Scanning Electron Microscope

An application of scanning electron microscopy (SEM) electron beam induced current (EBIC) technique for measurement of layer or strip resistance and sheet (surface) resistance is described. In the method a high electron beam current is used. In this range the EBIC (IEBIC) depends on the overall resistance of EBIC circuit. It includes a specimen resistance as well, as generated carriers create IEBIC current that flows along the measured layer or strip to an ohmic contact. A shift of the electron beam towards the ohmic contact on the layer (or on the strip) changes resistance of layer (or strip) between the e-beam placement and the contact. The change of resistance that results is compensated using a changeable resistance (e.g. a decade resistance box). Provided constant IEBIC despite the e-beam movement brings values of the resistance and the sheet resistance for the investigated layer or strip. Spatial distributions of resistance and local inhomogeneities can be also revealed. The method was used for the characterization of lateral confinements in semiconductor laser heterostructures manufactured by Molecular Beam Epitaxy and wet chemical or reactive ion etching. The method can be used for very thin layers and is expected to be applicable for small-size objects as nanostructures. [doi:10.2320/matertrans.48.949]

Introduction to the Ultrasound Guided Regional Anesthesia

The author introduces the ultrasound technique and the description of the sonoanatomy of brachial nerve block different blocks For one year ultrasound was introduced in our department as a tool for regional anesthesia and pain management. We would like to share our limited experience with our colleagues. The author introduces the ultrasound technique and the description of the sonoanatomy of brachial nerve block different blocks.. For peripheral blocks, the commonly used techniques at present are peripheral nerve stimulation and paraesthesia. These technique are essentially blinded techniques relying on anatomical landmarks to identify a needle entry point and guide the needle close enough to the nerve (within 0.5 cm) to allow either paraesthesia or electrical stimulation to confirm nerve location and identity.(1) Many techniques have been tried in the past including fluoroscopy (2), CT and MRI, although useful as a tool for research to investigate and modify existing techniques, they have impractical limitations for routine clinical application (3). Newer techniques such as percutaneous electrical guidance (PEG) and ultrasound may offer a real advance in both nerve location and identification. The use of ultrasound allows real time visualization of the nerves and the surrounding structures with real time guidance of the needle to the nerve and visual confirmation of the local anesthetic spreading around the nerve. Initial studies and results suggest that ultrasound guidance may decrease latency, improve success rates, eliminating or reducing serious complications (4,5). Any technique should ideally be able to fulfill the following criteria: Give information about the location of the target nerve and its relationship to neighboring structures (vascular structures, lung) Estimate or measure skin to nerve distance (depth of needle insertion) Help to determine angle and path that the needle needs to take. Supply real time visual and/or audio signals to show needle and guide to target nerve. Offer some indication of success of technique – ideally visualization of spread of local anesthesia. The principle of ultrasound imaging: US is sound wave with frequency greater than 20,000 cycles per second (20 kHz). US can direct as a beam, obeys the laws of reflection and refraction and is reflected by objects of small size. However, the amount of ultrasound reflected depends on the acoustic mismatch. Propagation through dense objects e.g. bone is poor with nearly the entire ultrasound beam reflected. As a result, bone generates a hyper echoic (bright) image as strong signal is returned to the emitting transducer. On the contrary, fat and tendon have low reflectivity thus they form hypo echoic (dark) images. The outline of an object is generally best delineated when the ultrasound beam is at 90 degrees. Generally speaking, nerves appear in the transverse (cross sectional) view as round to oval shaped structures that are nodular and they can be hypo echoic or hyper echoic depending on location. On the transverse view, peripheral nerves in cross section often appear to have an internal Introduction to the Ultrasound Guided Regional Anesthesia 2 of 5 honey comb texture. This corresponds to the parallel fascicular pattern noted on the longitudinal view. Figure 1 Figure 1a: Axillary approache to Brachial regional block The Probe and Needle. Figure 2 Figure 1b: Axillary sonography with mapping. Figure 3 Figure 2a: Supraclavicular Probe Introduction to the Ultrasound Guided Regional Anesthesia 3 of 5 Figure 4 Figure 2b: Supraclavicular sonogram. Figure 5 Figure 2c: Supraclavicular anesthetic spread. Figure 6 Figure 3a: Infraclavicular Probe and Needle placement Figure 7 Figure 3b: Infraclavicular sonography Introduction to the Ultrasound Guided Regional Anesthesia 4 of 5 CORRESPONDENCE TO Prof. Kamel Romdhane Consultant Anesthetist, ICU Pain Management Anesthesia Department Security Forces Hospital Program Email: kamelromdhane@hotmail.com Mobile # 0502892391

Preventing Damage by Hidden Objects in Vegetation

The paper presents the experimental radar-based sensor to operate in environment with vegetation cover for detection and discrimination there the small-sized invisible dielectric and metallic objects. This sensor constitutes a vehicle-housed emergency system for surveillance of area with vegetation ahead on the path of moving vehicle to prevent its contact with hidden objects. The emergency system functioning in basically implemented by real-time electromagnetic imaging of the scene of interest and its following image processing to enhance the target responses. The developed and tested experimental radar techniques are under consideration. The results of experimental examinations in field are presented and discussed.

Development of a high–resolution rapid prototyping system for small size objects

A high-resolution stereolithography (SL) system for fabricating small objects with complex microstructures has been developed. This novel SL system consists of a single mode He-Cd laser, an improved optical scanning system, a novel recoating system and a control system. A laser light spot with the diameter of 12.89 μm on the focal plane is obtained with the improved optical scanning system, and resin layers with the thickness of 20 μm can be built with the novel recoating system. Experimental studies were carried out to investigate the influences of the build parameters on the cured line width and depth with this novel SL system. The experimental results showed that the cured depth and width increase with the increasing ratio of laser power to scanning speed. And it is found that the cured line built using the high-resolution SL system is smaller in width and deeper in depth compared with the cured line fabricated in conventional SL system under the same scanning conditions. Based on the cured line width and depth obtained in the experiment, empirical equations predicting the cured line width and depth according to the ratio of laser power to scanning speed are established using a least-square fitting. The cured line width and depth predicted by the empirical equations provide a foundation to set up accurate line width compensation and appropriate layer thickness in the high-resolution SL system. Some small objects with microstructures have been fabricated with the new SL system.

Detection and tracking of objects from multiple airborne cameras

Video sensor networks play a vital role in unattended wide area surveillance. Most of the computer vision research in this area deals with networks of stationary electro-optical sensors. But recently there has been increased interest in networks using sensors on mobile platforms such as mobile robots, all-terrain vehicles, and unmanned aerial vehicles (UAVs). Here, we present novel computer-vision techniques for automatic object detection and tracking in mobile sensor networks. We use multiple commercial off-the-shelf (COTS) sensors that enable monitoring over large areas. The effectiveness of the object detection and tracking framework is demonstrated using aerial videos from multiple mobile sensors aboard UAVs (a sample UAV is shown in Figure 1). The goal of an effective video surveillance system is to detect objects in an area of interest and to find their correspondence across many frames. There are several issues inherent to the problem, such as rapidly changing lighting conditions (e.g. due to cloud cover), shadow, occlusion, and entry/exit of objects. The small size of objects taken through aerial imagery is another issue, making it difficult to detect and track through varying appearance and frequent occlusions. To ease this problem, we use object appearance, shape, and motion models to detect and track objects from a single UAV. Once the objects are tracked successfully, we apply geometric similarity between object trajectories across UAVs to obtain consistent labeling (global object correspondence). Conventional tracking methods that exploit appearance or position similarity are not suitable because of significant camera motion and object positional variation. So, we have developed the COCOA system, which uses three modules to achieve object detection and tracking in a single Figure 1. Shown is anUAV used in our experiments.

Novel stereolithography system for small size objects

PurposeTo satisfy the demands for rapid prototyped small‐size objects with intricate microstructures, a high‐resolution stereolithography (SL) system is developed.Design/methodology/approachThis novel SL system consists of a single mode He‐Cd laser, an improved optical scanning system, a novel recoating system and a control system. The improved optical system consists of a beam expander, an acoustic‐optic modulator, a galvanometric scanner and an F‐θ lens; the recoating system consists of roller pump, resins vat with an integrated high‐resolution translation stage and part building platform and a scraper. Experimental studies were performed to investigate the influences of building parameters on the cured line width and depth.FindingsWith the SL system, a laser light spot with a diameter of 12.89 μm on the focal plane and resin layers with a thickness of 20 μm have been obtained. The experimental results indicate that cured depth and width increase with the ratio of laser power to scanning speed, and cured line with a width of 12 μm and a depth of 28 μm was built, which showed the capability building microstructures with this new SL system.Research limitations/implicationsThe building area limited to 65 × 65 mm, is smaller than that of current SL system.Practical implicationsSmall objects with intricate microstructures can be fabricated with the SL system.Originality/valueThe high‐resolution SL system provides a solution to the problem that has hampered the progress of SL process into a high resolution ranges below 75 μm.

Intelligent Haptic Sensor System for Robotic Manipulation

Controlling robotic interventions on small devices creates important challenges on the sensing stage as resolution limitations of noncontact sensors are rapidly reached. The integration of haptic sensors to refine information provided by vision sensors appears as a very promising approach in the development of autonomous robotic systems because it reproduces the multiplicity of sensing sources used by humans. This paper discusses an intelligent multimodal sensor system developed to enhance the haptic control of robotic manipulations of small three-dimensional (3-D) objects. The proposed system combines a 16 /spl times/16 array of force sensing resistor (FSR) elements to refine 3-D shape measurements in selected areas previously monitored with a laser range finder. Using the integrated technologies, the sensor system is able to recognize small-size objects that cannot be accurately differentiated through range measurements and provides an estimate of the objects orientation. Characteristics of the system are demonstrated in the context of a robotic intervention that requires fine objects to be localized and identified for their shape and orientation.

Ultrasound‐guided microwave imaging of breast cancer: Tissue phantom and pilot clinical experiments

Microwave imaging promises high contrast between tumor and normal breast tissues, but its spatial resolution is limited. Here, we present a multimodality approach for high-resolution microwave imaging, where microwave image reconstruction is structurally guided by ultrasound imaging. The combined imaging concept is demonstrated using tissue phantom measurements obtained from a 16 x 15 transmitter/receiver microwave imaging system and a modified B-mode ultrasound system. With the geometry of the target and background known a priori from ultrasound, successful dielectric property images are recovered using a finite element-based reconstruction algorithm. We show that a target as small as 1.2 mm in diameter can be imaged with the multimodality approach, whereas it is impossible to detect such a small-size object using microwave imaging alone. The pilot clinical studies on two cases suggest that breast tumors can be much more accurately detected by the multimodality method.

Electrodynamics and ultimate SNR in parallel MR imaging.

The purpose of this article is to elucidate inherent limitations to the performance of parallel MRI. The study focuses on the ultimate signal-to-noise ratio (SNR), which refers to the maximum SNR permitted by the electrodynamics of the signal detection process. Using a spherical model object, it is shown that the behavior of the ultimate SNR imposes distinct limits on the acceleration rate in parallel imaging. For low and moderate acceleration, the ultimate SNR performance is nearly optimal, with geometry factors close to 1. However, for high reduction factors beyond a critical value, the ultimate performance deteriorates rapidly, corresponding to exponential growth of the geometry factor. The transition from optimal to deteriorating performance depends on the electrodynamic characteristics of the detected RF fields. In the near-field regime, i.e., for low B0 and small object size, the critical reduction factor is constant and approximately equal to four for 1D acceleration in the sphere. In the far-field wave regime the critical reduction factor is larger and increases both with B0 and object size. Therefore, it is concluded that parallel techniques hold particular promise for human MR imaging at very high field.

Orbit improvement for GEO objects using follow-up observations

During the preceding years, the Astronomical Institute of the University of Bern (AIUB) was conducting several search campaigns for space debris in the geostationary ring (GEO). The optical observations were performed with a 1-m Ritchey–Chrétien telescope on Tenerife. A substantial population of unknown, small-sized objects was found in these surveys. For all objects a circular orbit was determined using the discovery observations. In order to test the hypothesis of circular orbits – which most likely is not valid for all detected objects – it is necessary to determine eccentricities for at least a part of the population. This in turn requires follow-up observations of the detected objects. The improved orbits resulting from follow-up observations also increase the probability for a successful recovery of the object in subsequent nights. Eventually, follow-up observations over several nights yield “secure” orbits allowing to build up a catalogue. In this paper we present the results of the determination of circular orbits and the orbit improvement process yielding elliptical orbits. The accuracy of the determined orbits is discussed, and the orbit quality is tested with follow-up observations after a few nights. The orbital elements are compared with those based on the assumption of circular orbits.

Polarimetric Scattering From Two-Layered Two-Dimensional Random Rough Surfaces With and Without Buried Objects

A three-dimensional polarimetric analysis of the two-layered rough ground with and without buried objects is investigated here. A rigorous electromagnetic surface integral-equation-based model is used in this analysis. The statistical average of the polarimetric scattering matrix elements is computed based on the Monte Carlo simulations for both the vertically and horizontally polarized incident waves. The results show a significant impact on the scattered intensities due to the two-layer nature of the ground. However, these intensities show almost no difference between the ground signature with or without the object. On the other hand, the statistical average of the covariance matrix elements shows a distinct difference between these two signatures despite the small size of the buried object.