Details Of Internal Structure Research Articles

Structural diversification of the gustatory organs during metamorphosis in the alpine newt Triturus alpestris.

Gustatory organs of the taste bud type occur in the epithelial lining of the oropharyngeal cavity of alpine newt larvae. They resemble the taste buds of bony fish, both in appearance (as revealed by scanning electron microscopy) and in detailed internal structure (seen on transmission electron micropscopy). During metamorphosis, at stage 55 of development, the secondary tongue (i.e. the soft tongue) is well formed and the anlages of taste discs are clearly apparent. Somewhat later, taste discs also appear in the epithelial lining outside the tongue, paralleling the disappearance of the taste buds. Well-developed taste discs of the newt differ from taste buds mainly by their structurally diversified set of 'associate cells' (mucous, wing and glial cells), which have no synaptic contact with nerve fibres. These cells accompany the neurosensory cellular components of the taste disc, i.e. the taste receptor cells and basal cells. This indicates that gustatory organs in metamorphosed newts, regardless of their small dimensions, fulfil the criteria established for taste discs previously defined in other Caudata and Anura species. Therefore, in the development of the newt there are two subsequent types of gustatory organs and two generations of the tongue: primary, in the larvae, and secondary, in metamorphosed animals.

Dynamics of a High-Frequency Fuel Actuator and its Applications for Combustion Instability Control

The present paper performs complementary experimental and theoretical investigations of a pump-style, high-frequency, magnetostrictive fuel actuator, which achieves fuel modulations by periodically “pushing” fuel out of a piston-cylinder unit instead of by modulating the flow area. The low-order models are developed to identify relevant parameters and investigate their influences on fuel modulations. This fuel actuator is proprietary, its detailed internal structure and dimension are not available, so only qualitative comparisons between the model predictions and experiments are made. Experiments validate the trend of the model predictions. A system-identification-based LQG controller is designed to quickly suppress strong interferences of fuel modulations with the mean fuel flow rate. Improvements to the fuel setup have been made according to the model predictions, which have been experimentally shown to be beneficial to combustion instability control.

HDR VolVis: high dynamic range volume visualization

In this paper, we present an interactive high dynamic range volume visualization framework (HDR VolVis) for visualizing volumetric data with both high spatial and intensity resolutions. Volumes with high dynamic range values require high precision computing during the rendering process to preserve data precision. Furthermore, it is desirable to render high resolution volumes with low opacity values to reveal detailed internal structures, which also requires high precision compositing. High precision rendering will result in a high precision intermediate image (also known as high dynamic range image). Simply rounding up pixel values to regular display scales will result in loss of computed details. Our method performs high precision compositing followed by dynamic tone mapping to preserve details on regular display devices. Rendering high precision volume data requires corresponding resolution in the transfer function. To assist the users in designing a high resolution transfer function on a limited resolution display device, we propose a novel transfer function specification interface with nonlinear magnification of the density range and logarithmic scaling of the color/ opacity range. By leveraging modern commodity graphics hardware, multiresolution rendering techniques and out-of-core acceleration, our system can effectively produce an interactive visualization of large volume data, such as 2,048(3).

Two‐dimensional Stellar Evolution Code Including Arbitrary Magnetic Fields. I. Mathematical Techniques and Test Cases

A high-precision two-dimensional stellar evolution code has been developed for studying solar variability due to structural changes produced by varying internal magnetic fields of arbitrary configurations. Specifically, we are interested in modeling the effects of a dynamo-type field on the detailed internal structure and on the global parameters of the Sun. The high precision is required to model both very small solar changes (of the order of 10-4) and short timescales (of the order of 1 yr). It is accomplished by using the mass coordinate to replace the radial coordinate, by using fixed and adjustable time steps, a realistic stellar atmosphere, and element diffusion, and by adjusting the grid points. We have also built into the code the potential to subsequently include rotation and turbulence. The current code has been tested for several cases, including its ability to reproduce the one-dimensional results.

Comparing geophysical methods for talus slope investigations in the Turtmann valley (Swiss Alps)

Three geophysical methods, ground penetrating radar, 2D-resistivity and seismic refraction were applied to two landform complexes in a high-alpine valley in Switzerland to investigate their internal structure. Results of the different methods were analysed separately, before conclusions about sediment thickness and geomorphologic implications were drawn. The results from the three methods were compared to focus on the quality of the methods and their field utility, with respect to portability of equipment, required man-power and measurement time. In this study, ground penetrating radar and seismic refraction proved to be the most suitable with respect to the quality and resolution of the subsurface information and the level of field utility. Sediment thicknesses of 15 m on a rectilinear slope and more than 30 m on a talus cone have been measured; a backweathering rate of approximately 700 mm ka − 1 was established. Furthermore, the radar delivered detailed internal sediment structure as well as interfaces between talus and rock glacier. The combined geophysical investigation produced a detailed image of the subsurface composition of the two landform complexes that enhance the understanding of the paraglacial landform evolution in this hanging valley.

Microstructure Evolution in Deformed Copper and Nickel

ABSTRACTThe combined effect of strain and temperature on the microstructure and detailed internal structure of dislocation boundaries was systematically studied in compressed pure polycrystalline copper and nickel and compared to the microstructure of compressed polycrystalline aluminum. Below 0.5Tm the microstructure of Cu and Ni consists of dislocation cells, however, only in Cu second generation microbands are formed. In Cu and Ni, the dislocations inside the boundaries rearrange themselves from tangles to ordered arrays of parallel dislocations following interplay between strain (requirement for cross slip) and temperature (dislocation mobility and ease of cross slip). The ordered detailed structure is similar to that observed in Al deformed at room temperature and lower strain levels. The amount of strain and temperature applied to Cu and Ni in order to achieve the same detailed structure formed in Al depends on the stacking fault energy (SFE) of the metal- higher strain and temperature as the SFE is lower.

Structural concept of Japanese solid breeder test blanket modules for ITER

A solid breeder blanket was selected as the primary candidate blanket of the fusion power demonstration plant (DEMO plant) in Japan. Test blanket module (TBM) testing in ITER is the most important milestone for the development of the blanket of the DEMO plant. Therefore, the major development effort has been focused on the development of the TBMs in Japan. This paper presents a structural concept of solid breeder TBMs cooled by pressurized water and helium gas. In the sub-module concept which was developed, a slitted box structure was adopted for both TBMs to simulate the DEMO blanket structure and to endure the over-pressurization in case of the coolant ingress to box structure. The breeder and neutron multiplier formed by small pebbles are packed separately in a layered structure. Detailed internal structure was developed with consideration of fabrication procedure, coolant flow route and purge gas flow route. Coolant flow route was considered from the view points of thermal–hydraulic and heat transfer performances. As for He purge gas flow passages, separated passages for tritium breeder layers and neutron multiplier layers were adapted to avoid tritium migration to the neutron multiplier layers.

Gravity on codimension 2 brane worlds

We compute the matching conditions for a general thick codimension 2 brane, a necessary previous step towards the investigation of gravitational phenomena in codimension 2 braneworlds. We show that, provided the brane is weakly curved, they are specified by the integral in the extra dimensions of the brane energy-momentum, independently of its detailed internal structure. These general matching conditions can then be used as boundary conditions for the bulk solution. By evaluating Einstein equations at the brane boundary we are able to write an evolution equation for the induced metric on the brane depending only on physical brane parameters and the bulk energy-momentum tensor. We particularise to a cosmological metric and show that a realistic cosmology can be obtained in the simplest case of having just a non-zero cosmological constant in the bulk. We point out several parallelisms between this case and the codimension 1 brane worlds in an AdS space.

Spreading and dewetting in nanoscale lubrication

This article critically reviews the fundamental scientific tools, as well as constructs cohesive schemes for potential applications, relevant to the molecularly-thin liquid film technology. Our focus is to understand the nanoscale dynamic behavior of thin lubricant films, relevant to the emerging field of nanotechnology, especially for achieving durability and reliability in the nanoscale devices. Our goal is to present a unified and hybrid description of perfluoropolyether (PFPE) experiment, mesoscopic interpretation, microscopic simulation tools, and molecular design tools available up to now. The experimentation and theory for the physicochemical properties of ultra-thin PFPE films are used to examine liquid film in the sub-monolayer to multilayer regime. Methods for extracting spreading properties from the scanning microellipsometry (SME) for various PFPE/solid surface pairs and the surface rheological characterization of PFPEs are examined. The interrelationships among SME spreading profiles, rheology, surface energy, and tribology, are given. Mesoscopic theories, including thermodynamics of evaporation and flow, stability analysis, microscale mass transfer, and capillary waves are introduced to describe thin PFPE film dynamics. Estimation of thin film viscosity enhancement from vapor pressure suppression by dispersion force is reviewed. The method for experimental derivation of lubricant spreading profiles from contact angles is summarized. The implications of capillary waves, or thermal fluctuations, at the surface of polymeric lubricant films are also discussed. The lattice-based, simple reactive sphere Monte Carlo (MC) technique for examining the fundamentals of PFPE dynamics is illustrated. An off-lattice based bead–spring MC model is also introduced to capture a detailed internal structure of the PFPE molecules, and the molecular dynamics method is implemented for a full-scale nanostructural analysis of PFPE ultra-thin films. By systematically tuning the endgroup strengths of PFPE, we examined the physicochemical properties for thin liquid films of the various PFPE/solid surface pairings. These tools accurately describe the static and dynamic behavior of ultra-thin liquid films consistent with experimental findings and thus are suitable for examining the fundamental mechanisms of lubrication in nanoscale devices. Application of the next generation head–disk interface design in information storage device is briefly considered.

Late Holocene solifluction history reconstructed using tephrochronology

Abstract Phases of activity of four solifluction lobes at an altitude of 750–800 m are dated by tephrochronology at Snaefell, central eastern Iceland (64°48′ N 15°33′ E). The sample includes sorted lobes with tread gradients of 3–11° and unsorted (turf-banked terraces) in slope-foot locations. Trenches through lobe fronts reveal detailed internal structures picked out by multiple tephra layers. The tephras V1717, V1477, Ö1362, V870, Hekla-3 (2900 years bp and Hekla-4 (3800 years bp ) provide isochronous surfaces of known age whose deformation and disturbance indicate mass movement and/or cryoturbation of the soil cover. Undisturbed soil including the Hekla-3 tephra indicates an absence of solifluction prior to 2900 years bp . Several centuries after Hekla-3, gravel-rich horizons mark wide-spread frost heave and solifluction of hillslopes. Later stabilization of these lobes allowed the accumulation of aprons of aeolian sediment below lee-side risers. These aprons contain in situ mediaeval tephras, dating the inception of solifluction to a considerable time prior to Norse settlement. The likely period of this first phase of solifluction is the Later Bog Period of the Subatlantic, c. 2500-1000 years bp . The aprons are currently being overridden and deformed by solifluction lobes reactivated in the Little Ice Age.

A COMPARATIVE STUDY OF COMELICANIIDAE MERLA, 1930 (BRACHIOPODA: ATHYRIDIDA) FROM THE LOPINGIAN (LATE PERMIAN) OF SOUTH CHINA AND TRANSCAUCASIA IN AZERBAIJAN AND IRAN

Eleven athyridoid species are described and other related species are revised from the Lopingian (late Permian) of South China and Transcaucasia in southern Azerbaijan and northern Iran. The family Comelicaniidae Merla, 1930 is adopted. It includes six subfamilies, of which Araxathyriinae is proposed as a new subfamily. Comparisons of species based on detailed internal structures indicate that some previously commonly recorded species from South China and Transcaucasia actually belong to different genera. Araxathyris coexisted in the two regions. Comelicania, Gruntallina, Janiceps, Transcaucasathyris, and Comelicothyris are only found in the southern Alps, Hungary, and/or Transcaucasia; whereas Tongzithyris and Rectambitus are restricted to South China. Other new taxa are Transcaucasathyris n. gen., Araxathyris sinensis n. sp., Rectambitus xui n. sp., and R. spondomarginata n. sp.

The SuperMACHO Microlensing Survey

We present the first results from our next-generation microlensing survey, the Su- perMACHO project. We are using the CTIO 4m Blanco telescope and the MOSAIC imager to carry out a search for microlensing toward the Large Magellanic Cloud (LMC). We plan to ascertain the nature of the population responsible for the excess microlensing rate seen by the MACHO project. Our observing strategy is optimized to measure the differential microlensing rate across the face of the LMC. We find this derivative to be relatively insensitive to the details of the LMC's internal structure but a strong discriminant between Galactic halo and LMC self lensing. In December 2003 we completed our third year of survey operations. 2003 also marked the first year of real-time microlensing alerts and photometric and spectroscopic followup. We have extracted several dozen microlensing candidates, and we present some preliminary light curves and related information. Similar to the MACHO project, we find SNe behind the LMC to be a significant contaminant - this background has not been completely removed from our cur- rent single-color candidate sample. Our follow-up strategy is optimized to discriminate between SNe and true microlensing.

Integrated satellite observations of the 2001 eruption of Mt. Cleveland, Alaska

Satellite data were the primary source of information for the eruption of Mt. Cleveland, Alaska on 19 February, and 11 and 19 March 2001. Multiple data sets were used pre-, syn- and post-eruption to mitigate the hazard and determine an eruption chronology. The 19 February eruption was the largest of the three, resulting in a volcanic cloud that formed an arc over 1000 km long, moved to the NE across Alaska and was tracked using satellite data over more than a 50-h period. The volcanic cloud was “concurrently” detected on the GOES, AVHRR and MODIS data at various times and their respective signals compared. All three sensors detected a cloud that had a very similar shape and position but there were differences in their areal extent and internal structural detail. GOES data showed the largest volcanic cloud in terms of area, probably due to its oblique geometry. MODIS bands 31 and 32, which are comparable to GOES and AVHRR thermal infrared wavelengths, were the least effective single channels at detecting the volcanic cloud of those investigated (MODIS bands 28, 29, 31 and 32). MODIS bands 28 and 29 detected the largest volcanic clouds that could easily be distinguished from weather clouds. Of the split-window data, MODIS bands 29 minus band 32 detected the largest cloud, but the band 31 minus band 32 data showed the volcanic cloud with the most internal structural detail. The Puff tracking model accurately tracked the movement, and predicted the extent and shape of this complex cloud even into areas beyond satellite detection. Numerous thermal anomalies were also observed during the eruption on the twice-daily AVHRR data and the high spatial-resolution Landsat data. The high-resolution Radarsat data showed that the AVHRR thermal anomalies were due to lava and debris flow features and a newly formed fan along the west coast of the island. Field observations and images from a hand-held Forward Looking Infrared Radiometer (FLIR) showed that the flow features were ′a′a lava, debris flows and a warm debris fan along the west coast. Real-time satellite data were the primary tool used to monitor the eruption, track changes and to mitigate hazards. High-resolution data, even though coverage is infrequent, were critical in helping to identify volcanic processes and to compile an eruption chronology.

Effects of detailed information about dissection on intentions to bequeath bodies for use in teaching and research.

Almost all UK medical schools teach anatomy using human bodies that have been bequeathed specifically for the purpose. Persons intending to make this most generous gift should be fully informed about how their body will be used. If detailed descriptions of dissection reduce the number of bequests, then this traditional and effective approach to anatomy teaching will have to change. To determine what effect detailed information has on intentions to bequeath, the Department of Anatomy at Bristol University sent all 139 people who asked for information, between July and December 2001, a description of dissection that included the statement 'Anatomical examination requires that bodies be dissected (taken apart) so that the fine detail of internal structures can be seen. Organs, such as the heart, lungs and brain, are often removed from the body to allow for more detailed study.' Views were sought by questionnaire (response rate 88%). Ninety-nine per cent of respondents intended to bequeath their body and 88% would allow it to be used in research or teaching with the department to make the final decision. Thus the provision of detailed information about dissection should not reduce the number of bequests and this mechanism could, subject to law, make bodies available for research as well as for teaching.

Synchrotron Radiation Imaging of Internal Structures in Live Animals

Ionizing radiation has long been used in medicine since the discovery of X-rays. Diagnostic imaging using synchrotron radiation has been under investigation since Rubenstein et al. reported dual-energy iodine-K-edge subtraction coronary angiography. Recently, computed tomography (CT) and magnetic resonance imaging (MRI) have provided better quality results than conventional radiology, providing important information on human internal structures. However, such techniques are unable to detect fine micron sized structures for the early diagnosis of tumors, vascular diseases and other medical objectives. Third generation synchrotron X-rays are well known for their superiority in coherence and energy tunability with respect to conventional X-rays. Consequently, new contrast mechanisms with a superior spatial resolution are becoming available. Here we present the extremely fine details of live animal internal structures using unmonochromatized synchrotron X-rays (white beam) and a simple detector system. Natural movements of the internal organs are also shown. The results indicate that this imaging technique can be applied to investigating microstructures and evaluating the function of the internal organs. Furthermore, this imaging system may be applied to humans as the next tool beyond CT and MRI.

3-D dual gamma-ray computer axial tomography investigation of polymetallic nodules

Polymetallic nodules (PN) collected from the north-east Pacific Clarion-Clipperton region were investigated with a 192Ir dual-energy gamma-ray computer tomograph. Tomographic images depicting density and effective atomic number distribution of the same section were obtained. These images present a linear response for a broad range of sample densities (0.97–6.22 g/cm 3), and likewise effective atomic numbers (5.48–29). Sixty-five successive digital sections, each with a thickness of 0.8 mm, reveal the 3-D density as well as the effective atomic number distribution function over the entire nodule volume, allowing one to obtain virtual sections across any desired plane. The tomograms show many details of internal structure of the investigated nodule such as an old nucleus, fissure networks or layer structures. The total concentration of iron and manganese determined by this method was equal to 19.4±1.7%. Gamma-ray computer tomography considerably extends the quantitative analysis capability of classic X-ray computer tomography.

Three-Dimensional (3D) High-Frequency Ultrasound Images of Skin and an Eye

This report describes the three-dimensional (3D) visualization of skin and an eye using high-frequency ultrasound. A high-frequency ultrasound image has high resolution of the order of 10 µm and demonstrates the detailed internal structure of an organ. Therefore it is suitable for visualizing the structure of organs such as skin and the eye. The method of 3D visualization of skin and an eye we used is as follows. Initially, a high-frequency ultrasound image was obtained by using a transducer made of lead zirconate titanate (PZT) ceramics with a central frequency of 32 MHz. The spatial resolution of the image is 25 µm. Next, we applied a binarization procedure to the image and reconstructed a 3D image using a volume-rendering technique. From the results, we were able to separately image each layer of the skin and recognize the stratum corneum, epidermis and dermis. Moreover, we obtained images of the structure of the eye, that is, cornea and iris.

The effect of curvature on detonation waves in Type Ia supernovae

The effect of curvature on detonation speed and structure for detonation waves in C–O is investigated. Weakly curved detonation fronts have a sonic point inside the reaction zone. In such waves the detonation speed depends on the detailed internal structure and not on simple jump conditions. Hence, in order to obtain the correct propagation speed and products of burning, the reaction length-scales must be resolved in any numerical simulation involving curved detonations in C–O. For each value of the initial density there is a corresponding extinction curvature above which quasi-steady detonations cannot propagate. For densities less than 2×107 g cm−3, where the self-sustaining planar waves are Chapman–Jouguet, and for realistic values of the curvature, the sonic point moves from the end of silicon burning to the end of oxygen burning. Hence the effective detonation length, i.e. the length-scale of the burning between the shock and the sonic point which can affect the front, is several orders of magnitudes less than the planar waves predict. However, silicon burning, which occurs downstream of the sonic point, is increased in length by a few orders of magnitude owing to lower detonation speeds and temperatures. Therefore more intermediate-mass elements will be produced by incomplete burning if curvature is taken into account. Recent advances in detonation theory and modelling are also discussed in the context of Type Ia supernovae.

Etch Film and Pit Structure of AA1050 Aluminum Plates Electrograined in Nitric and Hydrochloric Acids

AA1050 aluminum lithographic plates were ac electrograined in nitric and hydrochloric acids. The surface morphology of the electrograined aluminum plate was characterized via scanning electron microscopy. In addition, detailed internal structure of the etch pits was examined using an epoxy replica method. The microstructure of the etch film was characterized by cross-sectional transmission electron microscopy. Experimental results indicate that the etch film overlaying the individual pit formed in nitric acid was a layered amorphous structure. Each layer of the etch film assumed the shape of the individual pit on which the etch film overlaid. Conversely, an amorphous etch film, which was not a layered structure, covered the fine pit formed in hydrochloric acid. The different filming behaviors observed were owing to the anions associated with the electrolytes, i.e., and of which the former aggressively induces the pitting corrosion on most aluminum alloys. Moreover, the morphology and size of the etch pits differed for the electrolytes employed. That is, the hemispherical individual pits led to the formation of convoluted pits formed in nitric acid, whereas the coalescence of fine pits caused the formation of convoluted pits during electrograining in hydrochloric acid. Our results further demonstrated that the individual pits formed in nitric acid were significantly larger than the fine pits formed in hydrochloric acid. © 2001 The Electrochemical Society. All rights reserved.

Magnetic resonance imaging analysis of embryos.

Analyzing phenotypic effects in embryos produced with directed gene manipulation is a major challenge for developmental biologists who are trained in molecular techniques but who are not well-versed in embryology. Analysis techniques that preserve the three-dimensional (3-D) integrity of the specimen while also demonstrating internal structural detail provide an advantage for researchers who are not prepared to study hundreds of optical histological sections and mentally reconstruct the embryo. Magnetic resonance (MR) imaging nondestructively generates 3-D and cross-sectional views of embryos to provide macroscopic structural detail while preserving the spatial information.