Few Millimeters In Size Research Articles

Mixed Lutetium Iodide Compounds

In this paper we present initial results on mixed LuI3-YI3-GdI3 scintillators for gamma and neutron detection. The scintillation properties were investigated and compared to the results obtained for the binary compositions. Small samples, few millimeters in size, were tested. Under X-ray excitation each crystal exhibits bright green emission in the 425 to 750 nm spectral range. The exact peak position depends slightly on the material composition. The emission is due to d-f transitions on the Ce3+ ion. The scintillation under gamma excitation is fast and decays with about 30 ns time constant. The rise time varies slightly and it can be as fast as 0.5 ns. The light output of the investigated samples varied from 115,000plusmn13,000 ph/MeV for LuI3 to 68,000plusmn8,000 ph/MeV for LuI3-YI3 composition. The energy resolution at 662 keV was difficult to estimate since the samples lacked in crystal quality. LuI3-GdI3 composition was also tested for the detection of thermal neutrons from a moderated 252Cf source. The neutron peak appears at 81 keV when compared to 60 keV peak in 241Am spectrum recorded under the same conditions. The light output per a single detected neutron is about ~6,350 photons.

Three-dimensional morphology of magmatic sulfides sheds light on ore formation and sulfide melt migration

The morphology of magmatic sulfides in igneous cumulates is controlled by the wetting properties of sulfide liquids against silicates. The formation of nickel sulfide ores, the behavior of sulfide liquids during mantle melting, and potentially the segregation of the Earth9s core, are all controlled by the ability of sulfide liquids to migrate through the pore space of partially molten silicates. Three-dimensional X-ray tomographic images of sulfide aggregates in komatiitic olivine cumulates indicate that sulfide liquids have a limited tendency to wet olivine crystals, forming interconnected networks only in the absence of silicate melt. Consequently, the ability of sulfide liquids to migrate through the pore space of olivine cumulates is limited. We conclude that disseminated sulfide ores in komatiites formed by accumulation of transported sulfide blebs a few millimeters in size, and not by settling of sulfide-olivine aggregates, and that sulfides accumulated in the proportions in which they are now found, rather than by percolation through cumulate pore space. It is unlikely that sulfide droplets can be entrained and carried from the mantle at low degrees of partial melting. Our results also support the hypothesis that segregation of the Earth9s core took place from a magma ocean, rather than by percolation of sulfidic melt through partially molten mantle.

Thwarting Tumors: Nereus Trolls for Cancer Cures beneath the Sea

Cancer tumors cannot grow more than a few millimeters in size, nor can they spread without developing their own network of blood vessels to supply oxygen and nutrients. Tumor blood vessels differ from normal blood vessels in that they are chaotic, leaky, and fragile. This difference makes them more susceptible to compounds that damage tumor blood vessels.

A Foraminiferal Parasite on the Sea Urchin Echinocorys: Ichnological Evidence from the Late Cretaceous (Lower Maastrichtian, Northern Germany)

In contrast to most other marine invertebrates, echinoderms favor the recognition of a syn vivo infestment of parasites and commensals by the specific response of their skeletal tissues. Attachment or embedment structures, but also repair features commonly mirror the anatomical morphology of the trace maker and may therefore be of interpretive value. Among the numerous groups of invertebrates associated with sea urchins, only a few are tightly attached to the external surface of the host, leaving visible damage on the skeleton. Here, we describe etched attachment scars, a few millimeters in size, produced by a circular to subcircular organism on the oral surface of the holasteroid echinoid Echinocorys perconica (von Hagenow, 1840) from the Lower Maastrichtian chalk of northern Germany. We compare the traces with Recent attachment scars produced by benthic foraminifers such as Hyrrokkin sarcophaga and consequently suggest a parasitic foraminifer as the most probable trace maker.

Noncontact Thermophysical Property Measurement by Levitation of a Thin Liquid Disk

The purpose of the current research program is to develop techniques for noncontact measurement of thermophysical properties of highly viscous liquids. The application would be for undercooled liquids that remain liquid even below the freezing point when suspended without a container. The approach being used here consists of carrying out thermocapillary flow and temperature measurements in a horizontally levitated, laser-heated thin glycerin disk. In a levitated state, the disk is flattened by an intense acoustic field. Such a disk has the advantage of a relatively low gravitational potential over the thickness, thus mitigating the buoyancy effects, and helping isolate the thermocapillary-driven flows. For the purpose of predicting the thermal properties from these measurements, it is necessary to develop a theoretical model of the thermal processes. Such a model has been developed, and, on the basis of the observed shape, the thickness is taken to be a minimum at the center with a gentle parabolic profile at both the top and the bottom surfaces. This minimum thickness is much smaller than the radius of disk drop and the ratio of thickness to radius becomes much less than unity. It is heated by laser beam in normal direction to the edge. A general three-dimensional momentum equation is transformed into a two-variable vorticity equation. For the highly viscous liquid, a few millimeters in size, Stokes equations adequately describe the flow. Additional approximations are made by considering average flow properties over the disk thickness in a manner similar to lubrication theory. In the same way, the three-dimensional energy equation is averaged over the disk thickness. With convection boundary condition at the surfaces, we integrate a general three-dimensional energy equation to get an averaged two-dimensional energy equation that has convection terms, conduction terms, and additional source terms corresponding to a Biot number. A finite-difference numerical approach is used to solve these steady-state governing equations in the cylindrical coordinate system. The calculations yield the temperature distribution and the thermally driven flow field. These results have been used to formulate a model that, in conjunction with experiments, has enabled the development of a method for the noncontact thermophysical property measurement of liquids.

Mechanism of Crystal Redistribution in a Sheet-like Magma Body: Constraints from the Nosappumisaki and Other Shoshonite Intrusions in the Nemuro Peninsula, Northern Japan

Processes of crystal separation in a magma heavily laden with crystals without phase change are investigated from observations on frozen magma systems: Nosappumisaki and other shoshonite intrusions in the Nemuro peninsula, Japan, for which the origin of the crystals and the initial conditions are well constrained. The Nosappumisaki intrusion is 120 m in thickness and extends for more than 1·5 km. It exhibits a wide range of lithological variation, principally as a result of crystal redistribution after intrusion. Crystals in each lithology can be clearly divided into two kinds according to their composition and texture: those present before the intrusion of the magma (‘phenocrysts’) and those that crystallized in situ after intrusion. From the vertical change in mode and size of ‘phenocrysts’, it is shown that (1) augite ‘phenocrysts’ were rapidly deposited, with little overgrowth after intrusion, by significant coagulation or clustering on a time-scale of more than a few years, and (2) plagioclase ‘phenocrysts’, definitely denser than the melt but concentrated in the upper level, floated by counter flow of massive deposition of augite ‘phenocrysts’. These results indicate that in a magma heavily laden with crystals of a few millimeters in size (>20 vol. %), crystal–crystal and crystal–melt interaction play an important role in the separation of crystals from the host melt.

Pictorial Essay: Multinodular Disease

The evaluation of patients presenting with multinodular pulmonary disease provides an important clinical challenge for physicians. The differential diagnosis includes an extensive list of benign and malignant processes making the management of these cases frequently problematic. With the introduction of high-resolution CT (HRCT) scanning, the ability to assess various patterns of diffuse multinodular disease has evolved into an essential part of the diagnostic process. The purpose of this article is to develop an approach to the diagnosis of multinodular parenchymal disease using HRCT scan pattern recognition as a point of departure.

CRYPTIC SPECIATION IN THE COSMOPOLITAN AND CLONAL HUMAN PATHOGENIC FUNGUS ASPERGILLUS FUMIGATUS

Microbes and other organisms smaller than one to a few millimeters in size are hypothesized to have global populations, in contrast to the geographically restricted ranges of larger organisms. However, fungi, which routinely have reproductive propagules no larger than 10 micrometers, challenge the generality of this hypothesis because recent studies have shown that globally distributed morphological species embrace two or more geographically restricted phylogenetic species. We used the concordance of gene genealogies to recognize phylogenetic species in the globally distributed opportunistic human pathogenic fungus, Aspergillus fumigatus. Based on DNA sequence data of five loci for each of 63 individuals collected from five continents, we have delineated two phylogenetic species in this single morphological species. Unlike all other fungi examined to date, both genetically isolated groups showed a global distribution with no evidence of a correlation between genotype and geographic location. Sexual reproduction has never been observed in A. fumigatus, but when the same data were used to explore the association of alleles at the five loci for one of the phylogenetic species, evidence was found to support recombination. The discovery of a cryptic species is medically relevant because different species are likely to differ in virulence or drug resistance. The discovery of a globally distributed A. fumigatus species clade highlights the need for ecological studies of the fungus to either document global dispersal or propose alternative mechanisms by which it persists as single, global phylogenetic population.

CRYPTIC SPECIATION IN THE COSMOPOLITAN AND CLONAL HUMAN PATHOGENIC FUNGUS ASPERGILLUS FUMIGATUS

Microbes and other organisms smaller than one to a few millimeters in size are hypothesized to have global populations, in contrast to the geographically restricted ranges of larger organisms. However, fungi, which routinely have reproductive propagules no larger than 10 micrometers, challenge the generality of this hypothesis because recent studies have shown that globally distributed morphological species embrace two or more geographically restricted phylogenetic species. We used the concordance of gene genealogies to recognize phylogenetic species in the globally distributed opportunistic human pathogenic fungus, Aspergillus fumigatus. Based on DNA sequence data of five loci for each of 63 individuals collected from five continents, we have delineated two phylogenetic species in this single morphological species. Unlike all other fungi examined to date, both genetically isolated groups showed a global distribution with no evidence of a correlation between genotype and geographic location. Sexual reproduction has never been observed in A. fumigatus, but when the same data were used to explore the association of alleles at the five loci for one of the phylogenetic species, evidence was found to support recombination. The discovery of a cryptic species is medically relevant because different species are likely to differ in virulence or drug resistance. The discovery of a globally distributed A. fumigatus species clade highlights the need for ecological studies of the fungus to either document global dispersal or propose alternative mechanisms by which it persists as single, global phylogenetic population.

Optical sectioning deep inside live embryos by selective plane illumination microscopy.

Large, living biological specimens present challenges to existing optical imaging techniques because of their absorptive and scattering properties. We developed selective plane illumination microscopy (SPIM) to generate multidimensional images of samples up to a few millimeters in size. The system combines two-dimensional illumination with orthogonal camera-based detection to achieve high-resolution, optically sectioned imaging throughout the sample, with minimal photodamage and at speeds capable of capturing transient biological phenomena. We used SPIM to visualize all muscles in vivo in the transgenic Medaka line Arnie, which expresses green fluorescent protein in muscle tissue. We also demonstrate that SPIM can be applied to visualize the embryogenesis of the relatively opaque Drosophila melanogaster in vivo.

Pulmonary tumorlets: CT findings.

Pulmonary tumorlets are defined in pathologic terms as benign localized neuroendocrine cell proliferations a few millimeters in size that are usually associated with damaged and ectatic small airways. The purpose of this study was to determine the frequency with which pulmonary tumorlets can be seen on CT and to describe their CT appearance. In 33 patients with proven tumorlets, a nodule was visible on CT in the same region as that of the resected specimen. Despite its ominous-sounding name, a pulmonary tumorlet represents benign tissue that may manifest as a subcentimeter pulmonary nodule and should be considered in the differential diagnosis of small pulmonary nodules visible on CT.

Electro-chemical reduction of MOX in LiCl

Unirradiated MOX fuel particles with a few millimeters in size were reduced to a U–Pu alloy by electro-chemical means. The reaction started at the grain-boundary and formed metallic coral-like frames. The Pu-concentration in the alloy was measured to be lower than that in the original MOX. Pu-spots were observed in regions that were originally at the site of MOX-agglomerates. These facts indicated that U was reduced prior to Pu during electro-chemical reduction.

Neutralizing vascular endothelial growth factor activity inhibits thyroid cancer growth in vivo

Abstract Background Without angiogenesis, tumours cannot grow larger than a few millimetres in size, the limit of diffusion. Vascular endothelial growth factor (VEGF) is an endothelial-specific mitogen and is a major regulator of physiological and pathological angiogenesis. Higher levels of VEGF messenger RNA expression and VEGF production and secretion have been found in FTC-133 cells than normal thyroid cells. Methods To investigate the relationship between VEGF and thyroid tumour angiogenesis and growth, human dermal matrix inoculated with FTC-133 cells was xenografted into nude mice or directly injected subcutaneously. To block the function of VEGF, the neutralizing anti-VEGF monoclonal antibody A.4.6.1 (mAb A.4.6.1) was injected intraperitoneally 100 μg per 0·2 ml twice weekly. As control, an antibody of the same isotype (immunoglobulin G1), directed against the gP120 protein (Ab 5B6), or phosphate-buffered saline (PBS) was used. To evaluate the dermal matrix as a model for angiogenesis studies, rhVEGF was inoculated into the dermal matrix pocket and xenografted into mice. Results In vivo study using the dermal matrix showed that the number of blood vessel ingrowths paralleled the concentration of rhVEGF and was highest at the concentration of 100 ng ml−1. Mice treated with the mAb A.4.6.1 developed fewer blood vessels (mean 7 per high-power field (HPF)) than control mice (18 per HPF in Ab 5B6 and 22 per HPF in PBS) (P < 0·01). The size of tumours between mAb A.4.6.1- and Ab 5B6- or PBS-treated groups showed a significant difference from the second week after the inoculation of FTC-133 cells. The tumours from mice treated with mAb A.4.6.1 were smaller (mean(s.d.) 0·09(0·02) g at 5 weeks) than tumours from mice treated with Ab 5B6 (5·38(1·15) g) or PBS (4·00(0·72) g) (P < 0·001, two-tailed unpaired t test). Conclusion VEGF is produced by thyroid cancer cell line FTC-133 and stimulates angiogenesis and growth of thyroid cancer. More importantly, this stimulation can be blocked by mAb A.4.6.1.

Fractured Reservoirs: Integration Is the Key to Optimization

Distinguished Author Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized to be experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering. Introduction New technologies in the last decade (most notably wellbore-image logs) have shown that the rocks in most hydrocarbon-bearing reservoirs contain faults and fractures. This observation has generated an intense interest in understanding "fractured reservoirs." As a result, numerous industry and academic groups are working on different facets of the problem. In addition to research efforts by most major oil companies, these include the Rock Fracture Project at Stanford U., the Rock Deformation Research Group at Leeds U., and the Fractured Reservoir Characterization Group of the Petroleum Engineering Dept. at the U. of Texas. Fractured reservoirs are defined here as reservoirs whose productivity and performance are controlled or strongly affected by faults and fractures occurring in the field. For a reservoir manager, four issues need to be addressed.Is there any evidence that faults and fractures are affecting the performance of my reservoir?If so, what is a description of their important features?How can that information be used to build a quantitative 3D model for performance prediction?How can the predictive model be applied to optimize production or ultimate recovery from this reservoir? Evidence of Fault/Fracture Control on Production " Effective" fractures are defined here as those fractures that impact reservoir production by enhancing flow, by partitioning the field, or by allowing early breakthrough of water or injected fluids. The ability to predict the presence of effective faults and fractures allows the reservoir engineer to collect appropriate data and to make good decisions while drilling the initial discovery and delineation wells on a prospect. Recent advances in seismic wavelet recording and processing [multicomponent recording, amplitude variation with offset (AVO)] hold the promise of being able to recognize a preferred anisotropy to wave propagation in the rocks that reflects an oriented arrangement of liquids in an existing fracture system.1 Seismic lines show major faults, and dip-attribute mapping combined with fault-interaction analysis based on structural principles allows prediction of an increasing amount of detail about the sealing nature of the fault zones.2 While drilling, interaction of the bit and the mud system with the in-situ stress in the rock determines borehole stability, completions strategy, and potential pipe failure throughout the life of the well. Recent work on small mud losses (less than 0.25 bbl in some cases) shows that, as a permeable fracture or fault zone is intersected by the wellbore, careful observation can document effective fractures, not just catastrophic mud loss.3 Other wellbore-based data sets that can be useful in identifying faults and fractures are structural logging of conventional core, rubble zones and core loss in fault-damage intervals, and image logs for viewing damage intersected by the bit. As a field is put on production, injection and production anomalies combined with transient-pressure testing give indications of reservoir compartments and allow better analysis of fluid-flow anisotropies.4 Detailed geochemistry of hydrocarbons can indicate compartments, and analysis of produced waters can differentiate in-situ water from aquifer fluids that have been coned through conductive faults and fractures. Combining these data with the various data types mentioned earlier can indicate that the existing effective-fault and -fracture network in a reservoir is strongly impacting performance. Description of Effective-Fracture Systems Describing the effective-fracture network in a reservoir must be done by integrating relevant data from wells (wireline logs and conventional cores), from well tests (production logs, interference tests, fluid typing), and from fieldwide observations (reservoir-scale 3D seismic and outcrop analogs). With these data, fracture types (extensional, compressional, shear, induced), geometries, properties (distributions of porosity and permeability), interaction with matrix, and deformation history can be determined and the effective-fracture system can be defined. Modern image-log data sets provide spectacular views of the borehole wall (visual and acoustic images) and the near-well rock volume (electrical images).5 These logs are capable of imaging features that are only a few millimeters in size. Fractures are often visible on these images (Fig. 1) and are easily measured in terms of physical and geometrical attributes (distribution attitude and aperture6). New sonic devices (dipole shear) use Stonely-wave propagation downhole to detect fluid-filled fractures that extend farther away from the wellbore.

Use of Electrocoagulation in the Treatment of Vesicovaginal Fistulas

The role of electrocoagulation for the treatment of vesicovaginal fistulas has not been clearly defined. To determine the use of this therapeutic modality, 15 cases of fistulas treated with electrocoagulation were retrospectively reviewed. Fulguration represented the primary treatment in 12 patients and the secondary treatment in 3 after an initial attempt at open surgical closure failed. In all instances fistula size was estimated to be 3.5 mm. or less. A Bugbee electrode, which was inserted into the fistula either cystoscopically or vaginally, was used to destroy the epithelial lining of the fistula tract. Following the procedure the bladder was decompressed with a large indwelling Foley catheter for at least 2 weeks. Fulguration was successful as the sole treatment modality in 9 of 12 patients (75%) and as an alternative intervention after failure of an open surgical repair in 2 of 3 (66%). Therefore, 11 of the 15 women (73%) had complete resolution of the fistulas with this technique. We conclude that fulguration is usually effective in managing patients with vesicovaginal fistulas a few millimeters in size or less. This technique should be used as an initial treatment for appropriately selected patients and in women with small residual fistulas after open surgical failure.

A Griggs deformation apparatus set up at Lille

ABSTRACTThe classical solid‐medium apparatus (Griggs apparatus) is generally viewed as a machine of poor accuracy with a large amount of uncertainty. However, a new generation of equipment with new assemblies and experimental procedures has greatly enhanced the capability of the apparatus. Experiments performed on the apparatus set up in our Laboratory on T‐oriented Yule Marble samples show that the yield strength of material can be measured with reasonable precision (within 10 MPa) and a yield strength as low as 50 MPa can be detected. The apparatus is particularly adapted to work on small specimens e.g. single crystals a few millimetres in size.

Ichnofacies of the Late Jurassic Smackover C"Sandstone, Claiborne and Webster Parishes, Louisiana: Indication of the Environment of Deposition"

The Smackover C sandstone of late Jurassic age has been an economic primary or secondary drilling target for several years. Recent drilling activity at Haynesville field and surrounding areas of Claibome and Webster Parishes has demonstrated the importance of the Smackover C sandstone as a hydrocarbon reservoir and has provided an abundance of well data including conventional cores from the interval. Ichnofossils (trace fossils) have been observed in several of the conventional cores taken through the Smackover C sandstone interval. These ichnofossils can be very important clues to the environment of deposition in which the Smackover C sandstone was deposited. An understanding of the environment of deposition will allow better exploitation of this particular lobe of Smackover C sandstone at Haynesville field and surrounding areas as well as aid the explorationist in searching for other similar deposits of the late Jurassic within the Gulf Coast basin. Ichnofossils as a whole are not abundant. On a scale from one to six the ichnofabric index (after Droser and Bottjer, 1986) is a one to two with the exception of a few interbedded shales that have an index of three. The three types of ichnofossils that have been recognized are dwelling structures (domichnia), feeding structures (fodinichnia), and escape structures (fugicnia). Ichnofossils of the Smackover C sandstone are normally found within 10 centimeters (four inches) of the sandstone-shale sediment interfaces (Figure 1) and are mostly horizontal with a few being vertical. The burrow diameters range in size from a few millimeters to 2.5 centimeters with most being just a few millimeters in size (Figures 1 and 2). Most of the burrows are filled with shale. Chondrites (Figure 1) is the most common ichnogenus observed but a few Planolites (Figure 2), 'Teichichnus, Scalarituba (Figure 3), Thalassinoides (Figures 4 and 5), Rhizocorallium and Conostichus have also been recognized. The actual presence of burrowing organisms in a vertical orientation together with the types of observed ichnogenera are both characteristic of the Cruziana ichnofacies. Burrowing organisms were either living in or were transported to the circalitoral transition zone offshore below storm weather wave base by event deposition. A shaley unit below the base of the sandstone in a core that was taken at the northwest margin of the lobe contained a large Thalassinoides (Figures 4 and 5) burrow. This would seem to suggest that water conditions were quiet and shallow just prior to deposition of the Smackover C sandstone. The Jurassic sea transgressed northward onto the continental margin creating an overall deepening-upward sequence. The depositional environment changed from a shallow inner shelf environment to a deeper middle shelf environment onto which sandstones were deposited by event deposition. Sediments were preserved because of the deepening sea conditions as the depositional lobe remained below storm weather base. The size, abundance, and diversity of the ichnogenera indicate an environment of very low oxygen. Depositional events and the transportation of sands offshore supplied oxygenated waters that allowed organisms to live. These depositional events are currently being studied to determine whether they were generated by storm or turbidite activity. Energy Development Corporation, 1200 Smith, #3040, Houston, TX 77002 Dept. of Geology, Centenary College, P.O. Box 41 188, Shreveport, LA 71134

Growth-sector dependence of optical features in large synthetic diamonds

Infrared, ultraviolet and cathodoluminescence measurements have been made on five synthetic diamonds which were grown using the temperature-gradient technique. The samples, which were a few millimeters in size, were chosen by virtue of having relatively well-developed {110} and {113} minor facets as well as {100} and {111} major faces. The samples, labelled I–V, were prepared in the form of polished plates. Sample I was a standard type Ib synthetic diamond. Infrared and ultraviolet absorption measurements were used to determine the concentration of isolated substitutional nitrogen present in the various types of growth sector. The {111} sectors contained about 100 ppm of nitrogen; the {100} sectors contained slightly less than 50 ppm; the {113} sectors contained of the order of 10 ppm and the {110} sectors contained approximately 1 ppm. For the remaining samples, II–V, the concentration of nitrogen incorporated during growth was greatly reduced by the introduction of nitrogen getters into the synthesis capsule. Even so, concentrations of a few ppm of nitrogen could generally be detected in {111} sectors. Sample II contained a concentration of 0.27 ppm of neutral boron acceptors in the (11¯0) sector despite the fact that boron had not been deliberately introduced during synthesis. The remaining three samples were deliberately doped with boron, the amount being less for sample III than for the samples IV and V. For sample III, the uncompensated acceptor concentration was highest in the {110} sectors, being approximately 3 ppm, approximately 0.9 ppm in the {113} sectors, 0.5 ppm in the {100} sectors and too small to be measured in the {111} sectors. For the highly-doped samples, IV and V, however, the uncompensated boron concentration was highest for the {111} sectors. Acceptor-centre zero-phonon lines are broadened out in {111} sectors, presumably as a result of higher defect concentrations in these sectors. Cathodoluminescence measurements at a temperature of approximately 90 K have revealed a new vibronic system with a zero-phonon line at 2.296 eV (539.9 nm). This system was observed only in the (11¯0) sector of sample I and in non-octahedral sectors of the other samples. The 2.56 eV (484 nm) cathodoluminescence system was present with high intensity in all {111} sectors of sample I but only in one {111} sector of sample II. It was absent from sample III and weak in sample IV. All samples exhibited spectrally-broad cathodoluminescence which consisted, in general, of two components, a blue band with a peak at 420 nm and a broader green band with a peak occuring between 490 and 540 nm.

Production and characterization of large-grain bulk samples of Y1Ba2Cu3O7−x

A heat-treatment method is described which yields superconducting Y1Ba2Cu3O7−x pellets having grain inclusions of a few millimeters in size. Resistivity, magnetic susceptibility, and magnetization display sharp transitions near 90 K for at least 85% of the volume of the samples. X-ray powder patterns reveal the presence of both the superconducting and ‘‘green’’ phases. Laue pictures show sharp spots. The normal state resistance of these samples is less than pellets prepared in the usual way by a factor of ∼10.

STEREOMICROSCOPE PHOTOGRAMMETRY FOR THE MEASUREMENT OF SMALL OBJECTS

AbstractA stereoscopic microscope has been used in combination with the body of a 35 mm camera to obtain stereophotographs, at scales up to 6:1, of objects only a few millimetres in size. Subsequent stereocomparator observations have been used to deduce height differences on the objects 10 a precision, for the mean of five sets of readings, of ±0.01 mm for closely spaced points. Using more widely separated points, the precision was estimated to be ± 0.05 mm. Depths were computed using × parallaxes after a number of parameters were fixed by calibration. The large convergence angle of the microscope axes was a crucial parameter; rotations about the camera axis were found to be significant variables.