Mode Of Scanning Research Articles

Dual-scan acquisition for accelerated continuous-wave EPR oximetry

Statistical analysis reveals that, given a fixed acquisition time, linewidth (and thus pO2) can be more precisely determined from multiple scans with different modulation amplitudes and sweep widths than from a single-scan. For a Lorentzian lineshape and an unknown but spatially uniform modulation amplitude, the analysis suggests the use of two scans, each occupying half of the total acquisition time. We term this mode of scanning as dual-scan acquisition. For unknown linewidths in a range [Γmin, Γmax], practical guidelines are provided for selecting the modulation amplitude and sweep width for each dual-scan component. Following these guidelines can allow for a 3–4 times reduction in spectroscopic acquisition time versus an optimized single-scan, without requiring hardware modifications. Findings are experimentally verified using L-band spectroscopy with an oxygen-sensitive particulate probe.

Development of Methodological Approaches for Examination of Particularly Dangerous Infectious Diseases Agents by Means of Atomic Power Microscopy

The atomic power microscopy (APM) is used to study the cell surface structure of particularly dangerous infectious diseases agents and to carry out the morphometric analysis. APM shows similar results with scanning electron microscopy. However, its application makes it possible to avoid time-consuming and labour-intensive procedures of samples preparing for testing by fixation, dehydration and sputtering of conducting layer. Methodological approach has been elaborated for preparing and analysis of samples of agents of particularly dangerous infectious diseases by means of APM. This approach includes a selection of optimal substrate, mode of disinfection and scanning of samples.

Analysis and simulation of the phenomenon of secondary spots of the TDI CCD camera irradiated by CW laser

The phenomenon of secondary spots is observed in the experiment of TDI CCD camera irradiated by CW He-Ne laser. It is considered to be related to the scattering of the slit in front of the sensor and the reflection of the window of the TDI CCD chip. Additional experiments and ray tracing simulation are performed to study the mechanism of the secondary spots. The experimental and simulated results demonstrated that the scattering of the side walls of the slit is the main source of the secondary spots. Furthermore, the operation mode of rotary scanning provides the chance of scattering incident beam to the side wall of the slit. This paper will provide a preliminary hint to the optimum design of slit in camera to reduce the effects of the secondary spots to the image quality.

Millimetre-wave radiometric imaging for concealed contraband detection on personnel

Millimetre-wave (MMW) radiometric imaging has established itself in a wide range of military and civil applications, but the fact that the radiometric temperature contrast between different objects indoors is low restricts the commercial application of MMW radiometric imaging to some extent. Based on the particular analysis of MMW radiometric imaging model suitable for concealed contraband detection on personnel, the method of adopting MMW noise source to illuminate the scene of being imaged to improve the radiometric temperature contrast, just like the flash lamp of camera, is proposed in this study. In addition, the choice of both the ways of illumination and the excess noise ratio (ENR) of the noise source is analysed. Then the image degradation model is discussed and the projection onto the convex sets (POCS) algorithm for MMW radiometric image super-resolution restoration is depicted in detail. In addition, a series of experiments are carried out both indoors and outdoors, with the dual-channel radiometric imaging system that has been implemented at W-band with the mode of two-dimensional planar scanning. The experimental results are presented and analysed to validate the significance of the imaging model and it is indicated that the radiometric imaging system is capable of detecting metal objects hidden underneath clothing, and the method of adopting noise illumination can improve the quality of radiometric images.

Genotyping Microarray for CSNB-Associated Genes

Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disease. Although electroretinographic (ERG) measurements can discriminate clinical subgroups, the identification of the underlying genetic defects has been complicated for CSNB because of genetic heterogeneity, the uncertainty about the mode of inheritance, and time-consuming and costly mutation scanning and direct sequencing approaches. To overcome these challenges and to generate a time- and cost-efficient mutation screening tool, the authors developed a CSNB genotyping microarray with arrayed primer extension (APEX) technology. To cover as many mutations as possible, a comprehensive literature search was performed, and DNA samples from a cohort of patients with CSNB were first sequenced directly in known CSNB genes. Subsequently, oligonucleotides were designed representing 126 sequence variations in RHO, CABP4, CACNA1F, CACNA2D4, GNAT1, GRM6, NYX, PDE6B, and SAG and spotted on the chip. Direct sequencing of genes known to be associated with CSNB in the study cohort revealed 21 mutations (12 novel and 9 previously reported). The resultant microarray containing oligonucleotides, which allow to detect 126 known and novel mutations, was 100% effective in determining the expected sequence changes in all known samples assessed. In addition, investigation of 34 patients with CSNB who were previously not genotyped revealed sequence variants in 18%, of which 15% are thought to be disease-causing mutations. This relatively inexpensive first-pass genetic testing device for patients with a diagnosis of CSNB will improve molecular diagnostics and genetic counseling of patients and their families and gives the opportunity to analyze whether, for example, more progressive disorders such as cone or cone-rod dystrophies underlie the same gene defects.

Dynamical phase separation under laser scanning

Dynamical patterns of microscopic phase segregation under linear scanning of the focus of IR laser were investigated in a homogeneous oil/water mixture. When the scanning frequency is low, the generated oil droplet follows the motion of the laser focus. When the frequency is high, the generated oil droplet is located at a certain position. The mechanism of these characteristic trapping patterns is discussed in terms of the effective potential by the focused laser beam, which depends on the scan rate and the mode of scanning.

Insights into the affine model for high-resolution satellite sensor orientation

As a model for sensor orientation and 3D geopositioning for high-resolution satellite imagery (HRSI), the affine transformation from object to image space has obvious advantages. Chief among these is that it is a straightforward linear model, comprising only eight parameters, which has been shown to yield sub-pixel geopositioning accuracy when applied to Ikonos stereo imagery. This paper aims to provide further insight into the affine model in order to understand why it performs as well as it does. Initially, the model is compared to counterpart, ‘rigorous’ affine transformation formulations which account for the conversion from a central perspective to affine image. Examination of these rigorous models sheds light on issues such as the effects of terrain and size of area, as well as upon the choice of reference coordinate system and the impact of the adopted scanning mode of the sensor. The results of application of the affine sensor orientation model to four multi-image Ikonos test field configurations are then presented. These illustrate the very high geopositioning accuracy attainable with the affine model, and illustrate that the model is not affected by size of area, but can be influenced to a modest extent by mountainous terrain, the mode of scanning and the choice of object space coordinate system. Above all, the affine model is shown to be both a robust and practical sensor orientation/triangulation model with high metric potential.

Pseudo-non-contact mode: why it can give true atomic resolution

Pseudo-non-contact (PNC) mode of scanning in atomic force microscopy (AFM) is a modification of the contact mode while the AFM tip and sample are immersed in a rather diluted aqueous surfactant solution. An additional repulsion due to the presence of surfactant leads to a decrease of the tip–sample interaction, mostly friction, during scanning. Experiments have shown considerable improvement in the resolution over a regular contact scanning. In this paper, further theoretical evidence is suggested that the PNC mode is capable of reaching the true atomic resolution, i.e., imaging of atomic defects. Forces acting between the AFM tip and sample under surfactant solution were measured. These data were used to simulate behavior of the AFM tip while scanning in the vicinity of an atomic defect, vacancy. It is shown that the scan force needed to remove the topmost atom is considerably higher in the presence of surfactant. Consequently, a regular force of a few nano-Newtons can be used in imaging with true atomic resolution.

Application of 3D computer-assisted techniques to sinonasal pathology—Case report: War wounds of paranasal sinuses caused by metallic foreign bodies

Foreign bodies in paranasal sinuses are found quite infrequently. They are usually detected after various types of head trauma and most commonly occur as a consequence of improper handling of firearms or explosives. In countries at war, eg, during the war in Croatia, adults and children were almost equally exposed to these injuries. The diagnosis should be based on results from precise computer tomography (CT) scanning in axial and coronal sections, and, using these data, tissues of different densities at these anatomical locations can be differentiated. The possibility of exact preoperative, noninvasive visualization of the spatial relationships of anatomic and pathologic structures with 3-dimensional (3D) computer-assisted diagnosis and intraoperative navigational techniques allows the surgeon to achieve a considerable advantage in the preoperative examination of the patient and to reduce the risk of intraoperative complications, all by the use of virtual surgery (VS) or virtual diagnosis. The expected contribution of the mentioned computer-assisted surgical technique manifests itself in defining the most appropriate mode of CT scanning of the head to design the 3D operating field model, and the possibility of active and dynamic 3D visualization of the desired anatomical regions is realized. 3D reconstruction of anatomic units becomes a routine preoperative procedure, providing a highly useful and informative visualization of the regions of interest, and, thus, advancing the definition of geometric information on anatomical contours of the 3D model by the transfer of so-called image pixel to contour pixel. (Am J Otolaryngol 2002;23:27-34. Copyright © 2002 by W.B. Saunders Company)

Lineshape effects in photoemission from the valence states of metals

The detailed appearance of photoelectron spectra from the valence bands of metals depends on many factors, including sample quality, and the experimental energy and angular resolution. Photoemission data are a function of at least two independent variables, the electron momentum k and the energy E; the interpretation of a spectrum can depend crucially on the mode of scanning. In addition, spectra from bulk states are influenced by intrinsic effects of the surface on the wavefunctions and the photoemission matrix element, and by the uncertainty in k caused by the finite lifetime of the excited photoelectron state. Spectra from effectively 2D systems, such as quantum wells and surface states, are free from ‘final state broadening’ and allow for relatively straightforward interpretations of peak widths in terms of state lifetimes. Contributions to the lifetime due to defects, phonons and the electron–electron interaction can be determined. In favourable systems and with sufficient resolution of the energy and momentum, spectra reveal non-quasi-particle behaviour of the electronic states due to many-body interactions.

Determination of polycyclic aromatic hydrocarbons (PAHs) in a complex mixture by second-derivative constant-energy synchronous spectrofluorimetry

In this work, the combination of the excellent band narrowing features of derivative spectrometry with constant-energy synchronous fluorescence spectrometry for the simultaneous determination of different polycyclic aromatic hydrocarbons (PAHs) in a mixture of 18 is assessed. This mode of scanning allowed for the identification and quantification of 10 PAHs and the grouping of some of these.

Dwell-time related effects in focused ion beam synthesis of cobalt disilicide

The influence of the high current density of a focused ion beam on the ion beam synthesis of CoSi2 layers has been investigated. After 35 keV Co+ or 70 keV Co2+ implantation into a heated Si(111) substrate and subsequent annealing, the layers have been investigated by scanning electron microscopy and Rutherford backscattering spectroscopy (RBS). It is shown that the mode of beam scanning influences the CoSi2 layer formation significantly. At a given substrate temperature, a sufficient low dwell time is required to obtain a continuous layer rather than a laterally disrupted structure. With increasing target temperature, the dwell-time window becomes less restricted. The results are discussed in terms of damaging and dynamic annealing of the silicon crystal. RBS channeling investigations demonstrate that continuous or disrupted CoSi2 layers are formed when the substrate remains crystalline or becomes amorphous, respectively.

Microsensors and Microsystems

Lateral structures of bare gold within self-assembled monolayers (SAMs) of gold alkanethiolates were created by electrochemical desorption in the direct mode of the scanning electrochemical microscope (SECM). The ultramicroelectrode (UME) of the SECM was positioned 10-20 μm above the surface and used as the auxiliary electrode in a three electrode cell with the SAM-coated Au electrode as working electrode. The microscopic auxiliary electrode causes an inhomogeneous electric field above the macroscopic gold electrode and limits the total current. As a consequence only thiols located directly beneath the UME are affected by the desorption procedure. Sample regions from which the SAM had been removed were imaged in the SECM feedback mode or, after galvanic Cu deposition, by scanning electron microscopy (SEM) and optical microscopy (after sulfidisation of Cu). The influence of hydrocarbon chain length, protection of the SAM by an additional layer of n-octanol and the use of alternating current were investigated in order to decrease the size of the bare surface areas and to enhance their edge definition. In particular the use of alternating current led to feature sizes of 1.2 times the UME diameter which represents an advance with regard to 2-3 UME diameters reported earlier.

Modelling of billet shapes in spray forming using a scanning atomizer

Abstract A numerical method is presented to predict and analyze the shape of a growing billet produced from the ‘spray forming’ which is a fairly new near-net shape manufacturing process. It is important to understand the mechanism of billet growth because one can obtain a billet with the desired final shape without secondary operations by accurate control of the process, and it can also serve as a base for heat transfer and deformation analyses. The shape of a growing billet is determined by the flow rate of the alloy melt, the mode of nozzle scanning which is due to cam profile, the initial position of the spray nozzle, scanning angle, and the withdrawal speed of the substrate. In the present study, a theoretical model was first established to predict the shape of the billet and next the effects of the most dominant processing conditions, such as withdrawal speed of the substrate and the cam profile, on the shape of the growing billet were studied. Process conditions were obtained to produce a billet with uniform diameter and flat top surface, and an ASP30 high speed steel billet was manufactured using the same process conditions established from the simulation.

A cognitive approach to English adverbs

The adverb has been understudied, compared with other grammatical categories such as nouns and verbs. Previous accounts of English adverbs such as Greenbaum (1969), Jackendoff (1972), Bellert (1977), Ernst (1984) assume that one only has to paraphrase the meanings of English adverbs as simply and formally as possible. These semantic-paraphrase analyses do not ask what underlies their paraphrases, much less what is a possible English adverb. The aim of this paper is threefold: to criticize the longstanding assumption that adverbs are too heterogeneous to be subject to a systematic treatment; to provide a cognitive-grammar (Langacker 1987a, 1990, 1991) account of English adverbs ; and to show that it contributes to constraining their range. It will be shown that English adverbs are much less idiosyncratic and heterogeneous than the previous analyses assume, with their semantic properties and syntactic behavior attributed to our ability to conceptualize a situation by means of alternate images. More specifically, adverbs will be defined as functions that map a verb (construed through sequential scanning) into some other mode of scanning or modal. Furthermore, it will be argued that the inventory of scanning and modal offers a natural way to constrain the range of English adverbs. All this strongly suggests that adverbs are no less amenable to a systematic treatment than nouns, verbs, and adjectives

Modeling of Billet Shape in Spray Forming Process

A numerical method is presented to predict and analyze the shape of a growing billet produced from the forming which is a fairly new near-net shape manufacturing process. It is important to understand the mechanism of billet growing because one can obtain a billet with the desired final shape without secondary operations by accurate control of the billet shape, and it can also serve as a base for heat transfer and deformation analysis. The shape of a growing billet is determined by the flow rate of the alloy melt, the mode of nozzle scanning which is due to cam profile, the initial positio of the spray nozzle, scanning angle, and the withdrawal speed of the substrate. In the present study, a theoretical model is first established to predict the shape of the billet and next the effects of the most dominent processing conditions, such as withdrawal speed of the substrate and the cam profile, on the shape of the growing billet are studied. Process conditions are obtained to produce a billet with uniform diameter and flat top surface, and an ASP30 high speed steel billet is manufactured using the same process conditions established from the simulation.imulation.

New high-pressure hot stage for optical microscopy

A new high-pressure optical hot-stage system combined with polarizing optical microscope has been constructed for in situ observation of optical texture of liquid crystals as well as polymers during the mode of either temperature or pressure scanning. It operated well in a temperature region between room temperature and 250 °C under hydrostatic pressures up to 300 MPa. The texture of a pressure-induced crystal polymorph of a dimesogenic liquid crystal was successfully observed.

Using force modulation to image surface elasticities with the atomic force microscope

Using a new mode of scanning, the force modulation mode, surfaces are imaged by the atomic force microscope. The new contrast mechanism relies on variation in the surface elasticity. The cross section of a carbon fibre and epoxy composite is imaged, showing contrast between the two materials. Surface elasticity variations across the cross section of the fibre are revealed. A lateral modulation mode is used to highlight atomic steps in gold.

Application of Synchronous Fluorescence Spectroscopy for Characterization of the Aromatic Hydrocarbons in Sediments of the Middle Adriatic

Abstract UV-fluorescence spectroscopy method with synchronous mode of scanning was used to characterize the types of aromatic hydrocarbons in surface sediments. the sampling stations were located on two transverses between Yugoslavian and the Italian coasts in the middle of the Adriatic Sea. the preparation of sediment samples was made according to IOC/UNESCO (1982). Synchronous excitation/emission scanning were done at wavelengths from 236/260 to 516/540 nm. Since the wavelength of maximum emission is a function of fused aromatic rings in a molecule, the fluorescence spectra of each sample were divided into three intervals: 300–340, 340–400, over 400 nm, corresponding to compounds with 2, 3 and 4,5 and more rings respectively. Large qualitative differences were established between sediment samples. PAH with 5 and more rings are more prevalent near the Italian coast.

Changes in infants' visual scanning across the 2- to 14-week age period

The characteristics of visual scanning over the 2- to 14-week age period were examined through repeated assessments conducted on a sample of 10 infants. Scanning patterns were measured using a bright-pupil corneal reflex system, and the stimuli consisted of various sets of static, moving, or flickering geometric figures. There appear to be a number of age-related changes in the dominant mode of visual scanning. At the youngest ages the infants' scanning often proved unrelated to the locations of the stimulus contours, and in instances where a stimulus figure was in fact attended the infants typically centered their regard on a single prominent feature. In contrast, as the infants grew older they more consistently directed their saccades toward stimulus contours, became increasingly disposed to scan between different stimulus features, and directed their saccades with increased accuracy. When a stimulus was flickering, however, the infants' scanning characteristics reverted to those typically found at younger ages. The mechanisms which might account for the effects of age and of stimulus quality on visual scanning are considered.