bluuebunny/crossref_metadata_2025 huggingface dataset:
A Nonsteady-State Thermal-Conductivity Tester for Cryogenic Insulations
Authors: Gibbon N. C. , Matsch L. C. , Wang D. I-J.
Published: August 2009

A test apparatus was developed to measure the thermal conductivity of cryogenic insulations in a high-vacuum environment without the need of achieving thermal equilibrium throughout the specimen. In this device, the rate at which an insulated body (insulated with the material being evaluated) cools is used to determine the thermal diffusivity from which the thermal conductivity of the material can be calculated. The main advantages of such a calorimeter are: (1) the need for attaining steady state, which is extremely time consuming and difficult experimentally, is eliminated; and (2) thermal conductivities over a wide range of temperatures can be measured all in one experiment. Two versions of the apparatus, one for vacuum powder and the other for vacuum super insulations (alternate-layer types), have been built and are in use. They have been used to measure thermal conductivities ranging from 0.012 to 0.00012 Btu in./hr ft2 deg F, including materials with an anisotropic thermal-conductivity ratio of 30,000 to 1. The theory of operation, description of the apparatus, instrumentation requirements, test procedure, and an example of data reduction to numerical values are presented. A comparison of data obtained using the nonsteady-state apparatus and calorimeters of conventional steady-state design is made.
An Improved Guarded-Cold-Plate Thermal-Conductivity Apparatus
Authors: Black I. A. , Wechsler A. E. , Glaser P. E. , Fountain J. A.
Published: August 2009

Construction details are presented for an improved 6-in.-diameter flat-plate calorimeter used in measuring thermal conductivity of evacuated or nonevacuated solid, foamed, fibrous, or particulate insulation materials. The apparatus incorporates the important features of the designs of an earlier 6-in. apparatus and the 12-in. double-guarded calorimeter and results in a compact self-contained unit which can be used with a standard 4-in. high vacuum pumping system. The measuring vessel of the apparatus is 3 in. in diameter; the guard ring vessel is 1 1/2 in. wide. The space between the warm and cold plates can be adjusted from outside the apparatus both before and during the test. Specimens up to 1 in. thick can be tested under a mechanical compression of up to 20 psi. The apparatus is designed to operate between 77 and 450 K. A thermostatically controlled oil bath is provided for controlling the temperature of the warm plate between 300 and 400 K. Techniques for control of warm-plate temperatures below 300 K are described, and the results of several performance tests using evacuated specimens are presented.
Crack Propagation and Residual Static Strength of Fatigue-Cracked Titanium and Steel Cylinders
Authors: Crichlow W. J. , Wells R. H.
Published: August 2009

Flight safety of the U. S. supersonic transport (SST) requires design data on the rate of crack propagation and the residual static strength of fatigue cracked cylinders. To provide these data an experimental test program was conducted on stiffened cylinders and curved and flat panels of titanium sheet (8A1-1Mo-1V duplex annealed) in the environments representative of SST operations (−110 F, room temperature, and +550 F) and on similar specimens of a candidate steel sheet material (PH-14-8Mo SRH 1050) at room temperatures. Cyclic pressure loading was applied to the cylinders and curved panels. Variation of hoop cross-section area and spacing on longitudinally stiffened cylinders provided design criteria for the crack-arresting properties of hoops in typical fuselage applications. Tension tests of flat panels with and without longitudinal straps provided data on material residual strengths and on the strap attachment qualities in the presence of transverse fatigue cracks. The experimental data were analyzed by means of several analytical formulas so that the design data could be interpreted and presented in compact and usable form.
Water for Industrial Processes
Authors: Partridge E. P.
Published: August 2009

The quality of water suitable for use in different industrial processes ranges widely. As a result, only broad criteria have been or should be established by state and interstate agencies for water for industrial operations. Industry itself has created relatively few criteria for the appearance properties, taste and odor, electrical conductivity (as a measure of dissolved salts), dissolved oxygen, and pH required for process operations where water of a particular quality is needed. The criteria determining the quality of a specific source of water will tend to become those for municipal water supply and recreation. Possible use of all or part of a river for transportation of wastes to a treatment plant should not, however, be arbitrarily eliminated from consideration.
Introduction
Authors: Johnson A. I.
Published: August 2009

The facility with which water, as well as other fluids, will move through, or be held in or drawn into, the pores of soils and rocks is very significant in many types of engineering, hydrologic, agricultural, and geologic problems. Permeability and capillarity that measure this facility thus represent some of the most important properties of soils and rocks and the determination of these properties is a most important aspect of the testing of these materials. These properties play a vital part in problems related to drainage of highways and agricultural lands, seepage through earth dams and levees, uplift pressure beneath concrete dams and other construction, estimating available groundwater storage, dewatering construction sites, moisture distribution above the groundwater table, recovery of petroleum from oil-bearing strata, groundwater recharge by wells or spreading basins, disposal of atomic and other wastes by well injection, and seepage pressures that cause earth slides. Although the permeability and capillarity tests of rocks and soils are quite simple in theory, many factors affect such tests, both in the field and in the laboratory. Thus, the movement of water through soils and rocks, whether driven by pressure or capillary forces, is immensely complicated. The testing engineer must be aware constantly of the many factors that may affect the results obtained from tests for permeability and capillarity. The empirical law discovered in 1856 by Darcy provides us with a fundamental law for flow of water through soils and rocks. This law has been extensively tested, and its validity apparently has been established under a wide variety of conditions. A knowledge of Darcy's law is essential to an understanding of the flow of water through soils and rocks and for analysis of the many problems mentioned previously. ASTM Committee D-18 on Soils and Rocks for Engineering Purposes has responsibility for developing methods of testing soils and rocks and for furthering research activity in the general field of properties and behavior of soils and rocks for engineering purposes. The members of Committee D-18, however, are very much aware that natural materials such as soil and rock cannot be treated like most controlled materials. Thus, quality soil and rock testing never should be a simple routine matter. As indicated by Holtz, soil and rock must be evaluated in terms of their past history, constituent parts, the treatment comtemplated, and the conditions to which they will be subjected. Thus, some details of soil and rock testing procedures must be flexible to take into account these factors, and experiment and judgment of a high order are demanded from the testing engineers.
Hydraulic Properties of Disturbed and Undisturbed Soils
Authors: Laliberte G. E. , Corey A. T.
Published: August 2009

A study was made to determine whether or not disturbed materials are suitable for modeling undisturbed porous media. One requirement for similitude between a model and prototype involving partially saturated flow is that the relationship between permeability and capillary pressure be similar. In the case of disturbed media, the relationship is usually represented by a straight line on a log-log plot for capillary pressures greater than the bubbling pressure. The requirement for similitude of media is satisfied if the slope is the same, provided the model is scaled in relation to the magnitude of the bubbling pressure. Apparently, a medium obtained by pulverizing the material at the site of the prototype usually would not be suitable for a model. Suitable disturbed materials are available, however, for modeling the undisturbed media studied to date. The relationship between permeability and capillary pressure for structured soils may not be adequately described by slopes of the function on a log-log plot alone. Further study is needed to determine the role of sample boundary effects for such materials. Unconsolidated sands usually are not suitable media for modeling structured soils, the pores of sands being more uniform in size.
Permeability and Capillarity in Petroleum Reservoir Engineering
Authors: Baptist O. C.
Published: August 2009

The common methods for determining permeability and capillarity are outlined, and the uses of these results in petroleum engineering are summarized. Most of the changes noted when the single-phase permeability of a specimen is determined with gas and with water are attributable to such factors as gas slippage, interactions between the media and the fluid, bacterial growths, and incomplete saturations. Multiphase permeability, used in most reservior calculations, is best determined by the unsteady-state displacement method. Analyses of data obtained from well tests are based either on the assumption of steady-state flow of incompressible fluids or the unsteady-state flow of slightly compressible fluids. Analyses of pressure buildup curves using the concept of unsteady-state flow are proving very useful in determining a variety of reservoir conditions such as permeability, well damage, reservoir volume, distance to faults, static reservoir pressure, and interference between wells. Capillary pressure relations, used to predict connate water saturation in the reservoir, are best determined by displacement of fluids through a semipermeable barrier. The centrifuge method gives good results in homogeneous specimens, while the mercury injection method is useful for specimens not containing swelling clay minerals.
Determination of Arsenic in Steels, Iron Ores, and Spelters by Atomic Absorption
Authors: Hill U. T.
Published: August 2009

The determination of arsenic by the atomic absorption method is indicated generally in the literature of most instrument manufacturers. Attempts to determine arsenic by the recommended procedure, however, have not been successful. As early as 1959, L'vov in Russia and later Massman in Germany investigated the determination of arsenic by the atomic absorption method and concluded that due to the almost complete absorption of the arsenic resonance line by products of acetylene combustion at 1937.6 Å the determination by conventional techniques was not possible. The introduction of electrically heated vaporizing techniques in an argon atmosphere suggested in these studies introduced involved instrumentation and is a departure from the conventional atomic absorption method. This study was undertaken to retain, if possible, the simplicity of the flame absorption method and meet the requirements of accuracy needed in metallurgical analysis for arsenic. It was found possible to overcome background absorption by changing to the 1890.4 Å line and the use of nitrous oxide flame. Also by precipitating the arsenic as the magnesium arsenate by the Weisz oven ring method a determination of arsenic could be made by determining the magnesium. With the introduction of the hydrogen argon flame, however, it became possible to determine arsenic with great accuracy at 1937.6 A following a rapid distillation procedure previously developed for a photometric method. Thus, it became possible to determine arsenic in all types of metallurgical products including iron ores, carbon, and high-alloy steels with accuracy equal to the photometric method.
Experiments with Instrumented Pile Groups in Sand
Authors: Vesić A. S.
Published: August 2009

Following a review of known past experiments with pile groups in sand, this paper presents the results of a research project devoted to comprehensive testing of large-scale models of pile groups in sand. The testing program included testing of four- and nine-pile groups of instrumented piles, with and without caps, in sand. The 4-in.-diameter, 60-in.-long piles were placed by jacking at spacings ranging from two to six pile diameters (center-to-center) into artificial deposits of dry and submerged sand in two soil situations: (a) homogeneous, medium dense sand (relative density about 65 percent) and (b) two-layer mass, consisting of an upper stratum of very loose sand (Dr ≈ 20 percent), underlain by a stratum of dense sand (Dr ≈ 80 percent). Parallel tests with single piles were made to allow comparison with behavior of single piles under otherwise identical conditions. The results indicate practically no group effects on ultimate point loads. However, a significant increase of ultimate skin loads is detected when the piles are placed in a group. The pile caps contribute to the overall bearing capacity of the groups inasmuch as they are supported by sand along their outer rim. The overall group efficiency of the entire group (with cap) in medium dense sand increases to a maximum of about 1.7 at spacings of three to four pile diameters, becoming somewhat lower with further increase of pile spacing. A sizeable part of the increase in bearing capacity comes from pile caps. If the loads transmitted by the caps are deduced, the group efficiency drops to a maximum of about 1.3. Measurements of axial loads in individual piles indicate little variation of load distribution in different loading stages. In the case of nine-pile group, the center pile carried from 20 to 50 percent more load than the average. The settlements of the groups are larger than those of individual piles carrying the same load. It appears that the group settlement ratio increases roughly as the square root of relative width of the pile group.
Lateral Load Tests on Instrumented Timber Piles
Authors: Alizadeh M.
Published: August 2009

This paper presents the results of field lateral load tests made on four instrumented timber piles in Morgan City, La. The test piles were instrumented, calibrated, driven, and tested under lateral loads during February and March 1966 at two sites adjacent to the Morgan City floodwall. Each test pile was instrumented with nine pairs of electrical SR-4 strain gages. The two test piles at each site were tested simultaneously by jacking the piles apart. Cyclic and repetitive load tests were made on the test piles. The following conclusions were made from the results of these tests and comparison of measured moments and pile head slopes with those computed based on the theoretical expressions: (1) timber piles are capable of supporting lateral loads, (2) the behavior of, and stresses in, timber piles under lateral loads can be evaluated using the theoretical solutions presently available, and (3) repeated loading causes an increase in the pile head deflection at a given load level. The ratio of the deflection after repeated loading to that of the first cycle loading increases with the increase in applied repetitive load.
Ductile Iron—Our Most Versatile Ferrous Casting Material
Authors: Henderson H. E.
Published: August 2009

Since the discovery of ductile iron two decades ago, this versatile material has shown a truly phenomenal growth. The ductile iron family of materials combines the processing advantages of cast iron, that is, low melting point, good fluidity and castability, excellent machinability, and good wear resistance, with the engineering advantages of steel, including high strength, toughness, ductility, hot workability, and hardenability. Both chemical composition and heat treatment affect the matrix structure and the graphite formation, which must be spheroidal in shape. Rigid production controls are employed to produce reliable ductile iron castings. A wide range of tensile strength, yield strength, and elongation is produced from a single chemical composition through heat treatment. ASTM specifications for the ductile iron family list grades of 120-90-02, 100-70-03, 80-55-06,65-45-12, and 60-40-18. Attention is now being given to alloying elements and special chemical composition to broaden the range of physical properties of ductile iron. Successful applications of the various grades of ductile iron, including alloy grades, are found in the automotive industry, steel mills, farm equipment, machine tools, pipe lines, road building equipment, and many other manufacturing industries.
Correlation of Dynamic Properties Test Equipment
Authors: Nemec J. E.
Published: August 2009

The search for greater accuracy and precision in the measurement of dynamic properties of elastomeric components used in the automotive industry is a never-ending endeavor. This paper considers the statistical approach to designed experiments for evaluation of individual test machine repeatability and test machine differences. The approach is a discussion of the “Analysis of Variance” (ANOVA) technique and the mechanics of solution. The accuracy and precision variables are then applied to the technique for analysis. Included are the results of a precision error experiment conducted at General Tire and a round-robin test program, which was conducted through the joint ASTM-SAE Technical Committees on Automotive Rubber (TCAR Section 11.65B), both using the ANOVA statistical approach. The MTS 830 employing the transmitted force test method was used in the round-robin.
Error Analysis of the Resonant Beam Rubber Testing Machine
Authors: Paul A. S. , Hillberry B. M.
Published: August 2009

Dynamic analysis of the resonant beam machine is presented. Equations typically used to determine the dynamic properties of a rubber product are derived from a simplified model. A complex mathematical model representing a more realistic parametric system identification is formulated. Using the complex model as standard, the errors in the results from the simplified model are identified quantitatively, and it is shown they can be considerable. The sensitivity of the errors to the system parameter variations is also shown. These machine errors may be virtually eliminated by measuring the transmitted force and displacement across the sample.
The Effective Use of Dynamic Testing in Raw Materials Development Programs
Authors: Puydak Robert C.
Published: August 2009

Dynamic test equipment is used to characterize elastomers and compounding ingredients for the purpose of selecting those most suitable for the various types of dynamic mountings and to develop formulations with balanced properties. Key measurements include modulus under conditions of dynamic vibration, damping, and the ratios by which these quantities change with changes in frequency, amplitude, and temperature. By appropriate selection of test specimen configuration and test conditions, additional data are generated which can guide the designer in the most effective use of the materials available and help define the relationships between the properties of mount materials and their effectiveness in controlling vibrations in vehicles.
Production and Quality Control of Elastomer Mounts
Authors: Koons R. R.
Published: August 2009

With the increasing emphasis on the dynamic performance of elastomer mounts, the rubber manufacturer has been required to develop, produce, and control elastomer mounts with more versatility and precision than ever before. To accomplish this, the rubber manufacturer has become more involved with dynamic testing and dynamic performance while working closer with the automotive industry on cooperative engineering programs and correlation testing. This paper will discuss the manufacturer's role in preproduction engineering programs and requirements, production control of mounts, and control related correlation.
Two-Point Probe Correction Factors
Authors: Dickey D. H.
Published: August 2009

The effects of sample boundaries on resistivity measurements made with a two-point spreading resistance probe are calculated for various boundary conditions. The results are presented in the form of dimensionless correction factors. The problem of depth-dependent resistivity in a thin layer is considered, and a method for correcting measurements on such layers is described.
The Preparation of Bevelled Surfaces for Spreading Resistance Probing by Diamond Grinding and Laser Measurement of Bevel Angles
Authors: Mayer A. , Shwartzman S.
Published: August 2009

A rapid and reproducible method for preparing bevelled surfaces on silicon has been developed as a preliminary to spreading resistance probe measurement of doping profiles or junction depth determination by staining. Several chips can be bevelled simultaneously. The sample is mounted on a carrier which is clamped on the tilting table of a microtome. The tilt is adjusted until a laser beam reflected from the surface to a calibrated wall chart is deflected to the desired angle. The bevel is then ground with a high-speed diamond wheel mounted on the microtome, taking cuts of several micrometers at a time. The bevel edge is clearly defined even for very shallow angles. The angle is accurately measured with the same laser. Because the ground surface is highly reflective, in contrast to a lapped surface, a good reading of very small angles of less than 30 minutes can be obtained. Up to a 6 meter base line is used with a lmw He-Ne laser and the reflection is visible in normal room light. Factors entering into spreading resistance are discussed, such as mechanical damage incurred in bevelling, probe impact damage, and surface cleanliness. Judged by spreading resistance, the amount of damage incurred during grinding is small and reproducible, provided care is taken to maintain the spindle so that it runs without vibrating.
Use of the Spreading Resistance Probe for the Characterization of Microsegregation in Silicon Crystals
Authors: Voltmer F. W. , Ruiz H. J.
Published: August 2009

A technique for using the spreading resistance probe to quantitatively characterize microsegregation in single crystal silicon is presented. For the first time, the use of Fourier Transformations of the resistivity is developed to provide accurate quantitative information as to the periodicity and amplitude of the various components giving rise to the resistivity variations. It is demonstrated that the probe is reproducible and is capable of measuring fluctuations in resistivity to ± 1 percent, which is well below the normally observed microsegregation. Examples of the use of the technique are given by characterizing microsegregation in two Czochralski grown crystals and one modified float zone crystal. The periodicity of the principle resistivity fluctuation of the Czochralski grown crystals is evaluated by Fourier transform analysis and agrees well with the anticipated fluctuations in impurity incorporation based on growth parameters.
The Impact Tube: A New Experimental Technique for Applying Impulse Loads
Authors: Gebard George
Published: August 2009

This paper is concerned with the development of a new experimental technique for applying loads of an impulsive nature to diaphragms or plates of various shapes. Briefly, this technique utilizes an adaptation of the shock tube principle which has been used successfully in the investigation of various supersonic aerodynamic problems. By rupturing a diaphragm which separates a high- and a low-pressure chamber, an expansion wave is created which travels toward the opposite wall of the high-pressure chamber containing the specimen under investigation. Behind the specimen is another high-pressure chamber. As the wave impinges on the specimen, a pressure differential between the second chamber and the pressure wave is applied to the specimen in an impulsive manner. This technique can be used to study the dynamic response of plates or the strength characteristics of membranes. Considerations involved in the design of the various components of the impact tube are discussed in detail. The results of an exploratory program on the dynamic pressure-strain relations in the yield region are presented for aluminum alloy 2S-O, annealed type 302 stainless steel, and annealed low-carbon steel.
Report on Elevated-Temperature Properties of Wrought Medium-Carbon Alloy Steels
Authors: Simmons Ward F. , Cross Howard C.
Published: August 2009

This report is a graphical summary of the elevated-temperature strength data for medium-carbon alloy steels. It includes summary curves for tensile strength; 0.2 per cent offset yield strength; per cent elongation and reduction in area; stresses for rupture in 100, 1000, 10,000, and 100,000 hr; and stresses for creep rates of 0.0001 and 0.00001 per cent per hour (one per cent in 10,000 and 100,000 hr). Data for 27 steels representing approximately a dozen alloy types are given. This report also contains data for a few miscellaneous low-carbon alloy steels.
Determination of Soldier Wants
Authors: Schaefer Willis C.
Published: August 2009

The determination of user-wants and their measurement is not a simple problem. This paper and this symposium will introduce an area which is not clearly defined as to its extent nor as to all of the significant variables. The data now existing in this field are limited in their representativeness. The general principles which are relevant require more elaboration and more confirming studies. That basic research in this area has been initiated and supported by the Office of the Quartermaster General is, in my opinion, a significant indication of the breadth of interest and willingness of this office to consider all possible contributions to the effectiveness of the mission of the Corps. The purpose of this presentation is to outline a range of problems and hypotheses which will lead to productive findings in the analysis of user acceptability of items of personal equipment. It is my belief that objective investigation of the psychological problems of user-wants can contribute to the over-all effectiveness of user-equipment performance. Let me trace some background. In December 1948, the Director of Research of the Food and Container Institute, Mr. Gelman, stated in a paper presented to the Research and Development Board of the Military Establishment the following: “During the past war Army personnel were provided with rations which were the best that could be assembled under the conditions which obtained at the time. These rations were complete ⃨ The items ⃨ had passed inspection tests including, in many instances, chemical examination for composition as regards nutrients, and microbiological tests for sanitation. However, in spite of these facts (which were probably not known nor cared about by the men), many ration items were refused by the soldiers, certain of them being almost universally rejected, others were consumed in limited amounts, and others at infrequent intervals. The nutritional program therefore fell short of assuring the Armed Forces a complete, well-balanced diet, and clearly indicated that the methods and criteria used in choosing items with which to make up rations were inadequate ⃨ The essential factor which had been neglected was that of acceptability. It was obvious from the experiences of the past war that in developing the most adequate rations this characteristic must be evaluated before placing a food item in a ration.”
Determination of Soldiers' Food Wants
Authors: Benedict R. Palmer
Published: August 2009

The application of consumer research methods to certain problems of Army feeding is described. Food preferences of troops in the Zone of Interior are investigated to provide a basis for planning more acceptable menus. Preliminary investigations of quantative measurement of food consumption is presented. A technique for sampling the Army in the Zone of Interior is presented together with some aspects of questionnaire development for food preference studies. The results of the studies are discussed in general terms.
The General Problem of Measurement
Authors: Stouffer S. A.
Published: August 2009

The methods to be discussed in this paper, dealing with psychological measurement with special reference to the problem of measuring consumer wants are old in principle, but their development in present form is new, and in many respects revolutionary. Asking people what they want or what they believe is as old as elections. But techniques for finding out quickly and accurately the attitudes of a population by querying only a small representative sample of the population are relatively new, and their potentialities are still imperfectly understood, not only by laymen, but even by those who are supposed to be, in various respects, experts. Some people still think of research in this area in terms of public opinion polls of state and national elections. Actually, the forecasting of elections is only a minute fraction of the work in this field. Despite all the perils of estimating not only what the public's preferences are at a given moment, but also of calculating the probability of a change between the time of interview and time of election, and of estimating who won't even bother to vote, election forecasting has an impressive batting average. One spectacular failure to name the winner, as in 1948, may close some people's eyes to the important fact that errors in scores of elections have always been within a range of 3 to 4 per cent. An error of only 3 to 4 per cent on most matters as variable as public attitudes is within almost any conceivable practical limit of tolerance. I do not want to leave the impression that all attitude or opinion research is as accurate as this. Some of, it may be more accurate; some of it may be much less. Research is now being undertaken to improve the techniques so that they will have greater reliability and validity.
The Strength of Gravel in Direct Shear
Authors: Hennes R. G.
Published: August 2009

For many engineering purposes it is not feasible to measure the shear strength of sand or gravel in the laboratory. In such cases estimates of internal friction can be based upon the grading of the aggregate. This paper presents the results of an attempt to correlate internal friction with grain size and shape for cohesionless material. Direct shear tests were run on river gravel and on crushed basalt. When no binder or cement is present, aggregates of uniform size are more stable than aggregates whose greater density is obtained by the addition of fractions of finer size.
Welding the Hy Steel
Authors: Flax R. W. , Keith R. E. , Randall M. D.
Published: August 2009

The principal advantages of the HY-steels are their good combination of strength and toughness over a wide temperature range and their good weldability in heavy sections with little preheat and no postweld heat treatment. This class of steels includes Ni-Cr-Mo steels designated HY-80 and HY-100 and a Ni-Cr-Mo-V steel tentatively designated HY-130. They are low-carbon steels that achieve their strength and toughness through a quenching and tempering heat treatment. The following welding processes and their proper application to the Hy-steels are discussed: (1) shielded metal-arc welding, (2) submerged-arc welding, (3) gas metal-arc welding, (4) Narrow-Gap welding, (5) gas tungsten-arc welding, (6) plasma arc welding, and (7) electron beam welding. HY-80 and HY-100 have 80,000 psi and 100,000 psi minimum yield strengths respectively, and very similar chemical compositions. In general, these alloys are considered highly weldable, and their as-welded properties are very good when proper welding procedures are used. HY-130 is a higher alloy quenched-and-tempered steel having a minimum yield strength of 130,000 psi. Development of filler materials for joining HY-130 has been hampered by the difficulty of obtaining the combination of high toughness and high strength required in the as-welded condition. Heat-affected-zone microcracking and weld- and base-metal delayed cracking have been problems in welding HY-80 and HY-100. These can, however, be controlled by proper melting and processing of the base materials during production and by exercising proper precautions during welding. HY-130 has shown sensitivity to weld-metal contamination by carbon, sulfur, phosphorus, hydrogen, oxygen, and nitrogen.
Downregulation of Functional Reelin Receptors in Projection Neurons Implies That Primary Reelin Action Occurs atEarly/Premigratory Stages
Authors: Uchida Takayuki , Baba Atsushi , Pérez-Martínez F. Javier , Hibi Terumasa , Miyata Takaki , Luque Juan M. , Nakajima Kazunori , Hattori Mitsuharu
Published: August 2009

Reelin signaling is essential for correct development of the mammalian brain. Reelin binds to apolipoprotein E receptor 2 and very low-density lipoprotein receptor and induces phosphorylation of Dab1. However, when and where these reactions occur is essentially unknown, and the primary function(s) of Reelin remain unclear.

Here, we used alkaline phosphatase fusion of the receptor-binding region of Reelin to quantitatively investigate the localization of functional Reelin receptors (i.e., those on the plasma membrane as mature forms) in the developing brain. In the wild-type cerebral cortex, they are mainly present in the intermediate and subventricular zones, as well as in radial fibers, but much less in the cell bodies of the cortical plate. Functional Reelin receptors are much more abundant in the Reelin-deficient cortical plate, indicating that Reelin induces their downregulation and that it begins before the neurons migrate out of the intermediate zone. In the wild-type cerebellum, functional Reelin receptors are mainly present in the cerebellar ventricular zone but scarcely expressed by Purkinje cells that have migrated out of it. It is thus strongly suggested that Reelin exerts critical actions on migrating projection neurons at their early/premigratory stages en route to their final destinations, in the developing cerebral cortex and cerebellum.
Natural Scene Categories Revealed in Distributed Patterns of Activity in the Human Brain
Authors: Walther Dirk B. , Caddigan Eamon , Fei-Fei Li , Beck Diane M.
Published: August 2009

Human subjects are extremely efficient at categorizing natural scenes, despite the fact that different classes of natural scenes often share similar image statistics. Thus far, however, it is unknown where and how complex natural scene categories are encoded and discriminated in the brain. We used functional magnetic resonance imaging (fMRI) and distributed pattern analysis to ask what regions of the brain can differentiate natural scene categories (such as forests vs mountains vs beaches). Using completely different exemplars of six natural scene categories for training and testing ensured that the classification algorithm was learning patterns associated with the category in general and not specific exemplars. We found that area V1, the parahippocampal place area (PPA), retrosplenial cortex (RSC), and lateral occipital complex (LOC) all contain information that distinguishes among natural scene categories. More importantly, correlations with human behavioral experiments suggest that the information present in the PPA, RSC, and LOC is likely to contribute to natural scene categorization by humans. Specifically, error patterns of predictions based on fMRI signals in these areas were significantly correlated with the behavioral errors of the subjects. Furthermore, both behavioral categorization performance and predictions from PPA exhibited a significant decrease in accuracy when scenes were presented up-down inverted. Together these results suggest that a network of regions, including the PPA, RSC, and LOC, contribute to the human ability to categorize natural scenes.
Reliable Coding Emerges from Coactivation of Climbing Fibers in Microbands of Cerebellar Purkinje Neurons
Authors: Ozden Ilker , Sullivan Megan R. , Lee H. Megan , Wang Samuel S.-H.
Published: August 2009

The inferior olive projects climbing fiber axons to cerebellar Purkinje neurons, where they trigger calcium-based dendritic spikes. These responses dynamically shape the immediate spike output of Purkinje cells as well as provide an instructive signal to guide long-term plasticity. Climbing fibers typically fire approximately once a second, and the instructive role is distributed over many such firing events. However, transmission of salient information on an immediate basis needs to occur on a shorter timescale during which a Purkinje cell would typically be activated by a climbing fiber only once. Here we show usingin vivocalcium imaging in anesthetized mice and rats that sensory events are rapidly and reliably represented by momentary, simultaneous coactivation of microbands of adjacent Purkinje cells. Microbands were sagittally oriented and spanned up to 100 μm mediolaterally, representing hundreds of Purkinje cells distributed over multiple folia. Spontaneous and sensory-evoked microbands followed boundaries that were close or identical to one another and were desynchronized by olivary injection of the gap junction blocker mefloquine, indicating that excitation to the olive is converted to synchronized firing by electrical coupling. One-time activation of microbands could distinguish a sensory response from spontaneous activity with up to 98% accuracy. Given the anatomy of the olivocerebellar system, microband synchrony may shape the output of neurons in the cerebellar nuclei either via powerful inhibition by Purkinje cells or by direct monosynaptic excitation from the inferior olive.
Anticipatory and Stimulus-Evoked Blood Oxygenation Level-Dependent Modulations Related to Spatial Attention Reflect a Common Additive Signal
Authors: Sylvester Chad M. , Shulman Gordon L. , Jack Anthony I. , Corbetta Maurizio
Published: August 2009

Covert attention is associated with prestimulus blood oxygenation level-dependent (BOLD) modulations in visual cortex. In some situations, this preparatory activity can predict how well human subjects will perceive upcoming visual objects. Preparatory activity may mediate this behavioral effect by affecting the stimulus-evoked response, but the relationship between preparatory and stimulus-evoked BOLD modulations is unclear. Here, we examine this relationship by comparing the effects of spatial attention on anticipatory and stimulus-evoked signals and by measuring the trial-to-trial correlation between prestimulus and poststimulus modulations. We find that in extrastriate visual cortex (V4), modulations related to spatial attention are relatively large, extend from prestimulus through the peak of the evoked response, and are slightly larger in the evoked response compared with the prestimulus response. In striate cortex (V1), the frontal eye fields (FEF), and the intraparietal sulcus (IPS), modulations related to spatial attention are relatively small, are confined primarily to the prestimulus period, and are slightly larger in preparatory versus stimulus-evoked activity. Importantly, across visual cortex, the attentional biases (activity for attended versus unattended locations) in preparatory and evoked activity are more positively correlated, trial-by-trial, than would be expected on the basis of activity measured in subjects at rest. We argue that this pattern of results suggests that the same mechanisms underlie preparatory and stimulus-evoked BOLD modulations related to spatial attention and that incoming sensory signals add to preexistent biases in preparatory activity to generate the stimulus-evoked response.
PACS-1 Mediates Phosphorylation-Dependent Ciliary Trafficking of the Cyclic-Nucleotide-Gated Channel in Olfactory Sensory Neurons
Authors: Jenkins Paul M. , Zhang Lian , Thomas Gary , Martens Jeffrey R.
Published: August 2009

Impaired ciliary protein transport in olfactory sensory neurons (OSNs) leads to anosmia, and is a newly recognized clinical manifestation of a class of human disorders called ciliopathies. Surprisingly little is known regarding the mechanisms controlling trafficking to this unique neuronal compartment. Here, we show a novel role for phosphofurin acidic cluster-sorting protein 1 (PACS-1) in the ciliary trafficking of the olfactory cyclic-nucleotide-gated (CNG) channel. PACS-1 is an intracellular sorting protein that mediates its effects through the binding of acidic clusters on cargo protein. This interaction is dependent on CK2 phosphorylation of both PACS-1 and its cargo. We show that CNGB1b contains two putative PACS-1 binding sites, which are phosphorylated by the serine/threonine protein kinase, CK2. Additionally, we show that PACS-1 is expressed in OSNs and interacts in complex with the CNG channel. CK2 inhibition in native OSNs causes a loss of CNG channel from cilia and subsequent olfactory dysfunction, while adenoviral expression of mutant PACS-1 causes similar mislocalization. These results provide a mechanism for the subunit-dependent ciliary trafficking of the CNG channel and offer insight into the mechanisms of ciliary transport.
β-Amyloid Monomers Are Neuroprotective
Authors: Giuffrida Maria Laura , Caraci Filippo , Pignataro Bruno , Cataldo Sebastiano , De Bona Paolo , Bruno Valeria , Molinaro Gemma , Pappalardo Giuseppe , Messina Angela , Palmigiano Angelo , Garozzo Domenico , Nicoletti Ferdinando , Rizzarelli Enrico , Copani Agata
Published: August 2009

The 42-aa-long β-amyloid protein—Aβ1-42—is thought to play a central role in the pathogenesis of Alzheimer's disease (AD) (Walsh and Selkoe, 2007). Data from AD brain (Shankar et al., 2008), transgenic APP (amyloid precursor protein)-overexpressing mice (Lesné et al., 2006), and neuronal cultures treated with synthetic Aβ peptides (Lambert et al., 1998) indicate that self-association of Aβ1-42monomers into soluble oligomers is required for neurotoxicity. The function of monomeric Aβ1-42is unknown. The evidence that Aβ1-42is present in the brain and CSF of normal individuals suggests that the peptide is physiologically active (Shoji, 2002). Here we show that synthetic Aβ1-42monomers support the survival of developing neurons under conditions of trophic deprivation and protect mature neurons against excitotoxic death, a process that contributes to the overall neurodegeneration associated with AD. The neuroprotective action of Aβ1-42monomers was mediated by the activation of the PI-3-K (phosphatidylinositol-3-kinase) pathway, and involved the stimulation of IGF-1 (insulin-like growth factor-1) receptors and/or other receptors of the insulin superfamily. Interestingly, monomers of Aβ1-42carrying the Arctic mutation (E22G) associated with familiar AD (Nilsberth et al., 2001) were not neuroprotective. We suggest that pathological aggregation of Aβ1-42may also cause neurodegeneration by depriving neurons of the protective activity of Aβ1-42monomers. This “loss-of-function” hypothesis of neuronal death should be taken into consideration when designing therapies aimed at reducing Aβ burden.
Visual Receptive Field Structure of Cortical Inhibitory Neurons Revealed by Two-Photon Imaging Guided Recording
Authors: Liu Bao-hua , Li Pingyang , Li Ya-tang , Sun Yujiao J. , Yanagawa Yuchio , Obata Kunihiko , Zhang Li I. , Tao Huizhong W.
Published: August 2009

Synaptic inhibition plays an important role in shaping receptive field (RF) properties in the visual cortex. However, the underlying mechanisms remain not well understood, partly because of difficulties in systematically studying functional properties of cortical inhibitory neuronsin vivo. Here, we established two-photon imaging guided cell-attached recordings from genetically labeled inhibitory neurons and nearby “shadowed” excitatory neurons in the primary visual cortex of adult mice. Our results revealed that in layer 2/3, the majority of excitatory neurons exhibited both On and Off spike subfields, with their spatial arrangement varying from being completely segregated to overlapped. In contrast, most layer 4 excitatory neurons exhibited only one discernable subfield. Interestingly, no RF structure with significantly segregated On and Off subfields was observed for layer 2/3 inhibitory neurons of either the fast-spike or regular-spike type. They predominantly possessed overlapped On and Off subfields with a significantly larger size than the excitatory neurons and exhibited much weaker orientation tuning. These results from the mouse visual cortex suggest that different from the push-pull model proposed for simple cells, layer 2/3 simple-type neurons with segregated spike On and Off subfields likely receive spatially overlapped inhibitory On and Off inputs. We propose that the phase-insensitive inhibition can enhance the spatial distinctiveness of On and Off subfields through a gain control mechanism.
DNA-Based MRI Probes for Specific Detection of Chronic Exposure to Amphetamine in Living Brains
Authors: Liu Christina H. , Ren Jia Q. , Yang Jinsheng , Liu Charng-ming , Mandeville Joseph B. , Rosen Bruce R. , Bhide Pradeep G. , Yanagawa Yuchio , Liu Philip K.
Published: August 2009

We designed phosphorothioate-modified DNA probes linked to superparamagnetic iron oxide nanoparticles (SPION) forin vivomagnetic resonance imaging (MRI) of fosB and ΔfosB mRNA after amphetamine (AMPH) exposure in mice. Specificity of both the fosB and ΔfosB probes was verified byin vitroreverse transcriptase-PCR amplification to a single fragment of total cDNA obtained from acutely AMPH-exposed mouse brains. We confirmed time-dependent uptake and retention profiles of both probes in neurons of GAD67-green fluorescent protein knock-in mice. MRI signal of SPION-labeled fosB probe delivered via intracerebroventricular route was elevated in both acutely and chronically AMPH-exposed mice; the signal was suppressed by dopaminergic receptor antagonist pretreatment. SPION-labeled ΔfosB probe signal elevation occurred only in chronically AMPH-exposed mice. Thein vivotarget specificity of these probes permits reliable MRI visualization of AMPH-induced differential elevations of fosB and ΔfosB mRNA in living brains.
Dynamic Associations in the Cerebellar–Motoneuron Network during Motor Learning
Authors: Sánchez-Campusano Raudel , Gruart Agnès , Delgado-García José M.
Published: August 2009

We assessed here true causal directionalities in cerebellar–motoneuron (MN) network associations during the classical conditioning of eyelid responses. For this, the firing activities of identified facial MNs and cerebellar interpositus (IP) nucleus neurons were recorded during the acquisition of this type of associative learning in alert behaving cats. Simultaneously, the eyelid conditioned response (CR) and the EMG activity of the orbicularis oculi (OO) muscle were recorded. Nonlinear association analysis and time-dependent causality method allowed us to determine the asymmetry, time delays, direction in coupling, and functional interdependences between neuronal recordings and learned motor responses. We concluded that the functional nonlinear association between the IP neurons and OO muscle activities was bidirectional and asymmetric, and the time delays in the two directions of coupling always lagged the start of the CR. Additionally, the strength of coupling depended inversely on the level of expression of eyeblink CRs, whereas causal inferences were significantly dependent on the phase information status. In contrast, the functional association between OO MNs and OO muscle activities was unidirectional and quasisymmetric, and the time delays in coupling were always of opposed signs. Moreover, information transfer in cerebellar–MN network associations during the learning process required a “driving common source” that induced the mere “modulating coupling” of the IP nucleus with the final common pathway for the eyelid motor system. Thus, it can be proposed that the cerebellum is always looking back and reevaluating its own function, using the information acquired in the process, to play a modulating-reinforcing role in motor learning.