bluuebunny/crossref_metadata_2025 huggingface dataset:
An algebraic semantic framework for object oriented languages with concurrency (extended abstract)
Authors: Breu Ruth , Zucca Elena
Published: February 2005

This paper presents an algebraic semantics schema for object oriented languages including concurrent features. A class, the basic syntactic unit of an object oriented language, in our approach denotes a set of algebras determined by an algebraic specification. This specification describes a system of (possibly active) objects interacting via method calls. Extending other approaches, structured classes are modelled in a fully compositional way. This means that the semantic counterpart of class combinators such as inheritance and clientship are specification combinators. A model of records with sharing allows us to describe typical object oriented features like object sharing, inheritance polymorphism and dynamic binding. For modelling the dynamic behaviour of objects, we rely on an algebraic description of labelled transition systems.
Impact of performance considerations on formal specification design
Authors: Sitaraman Murali
Published: February 2005

Different client applications of a given functional behaviour usually have different performance requirements. Designing a formal interface specification of the functional behaviour to allow for alternative implementations, and hence, to be suitable for clients with varying performance requirements, is a challenging task. The specifier must consider ramifications of alternative designs on performance to produce a truly implementation-neutral (and hence, performance-neutral) functionality specification. This paper illustrates the influence of performance-both duration and capacity — considerations using a case study in object-based software specification. When these considerations are combined with concerns for comprehensibility and full abstraction, specifications that result that are arguably among the most desirable.
Real-time refinement in Manna and Pnueli's temporal logic
Authors: Scholefield David
Published: February 2005

A refinement calculus for the development of real-time systems is presented. The calculus is based upon a wide-spectrum language called TAM (the Temporal Agent Model), within which both functional and timing properties can be expressed in either abstract or concrete terms. A specification oriented semantics is given for the language. Program development is considered as a refinement process i.e. the
calculation of
a structured program from an unstructured specification. An example program is developed.
Intermittent hypoxia modulates Na+ channel expression in developing mouse brain
Authors: Zhao Peng , Xue Jin , Gu Xiang‐Qun , Haddad Gabriel G. , Xia Ying
Published: February 2005

Because our previous work showed that intermittent hypoxia alters neuronal excitability and Na+ current density, we examined in this work the effect of intermittent hypoxia on Na+ channel subtypes using 3H‐saxitoxin (3H‐STX) autoradiography and immunoblotting. Mice were exposed to intermittent hypoxia for 2 or 4 weeks from postnatal day 2 or 3. A 2‐week intermittent hypoxia reduced cerebral STX binding density with significant decrease in Nav1.2 in the rostral and Nav1.1 in the caudal regions. In contrast, a 4‐week intermittent hypoxia tended to increase STX binding density in most brain regions. Our data suggest that intermittent hypoxia differentially regulates plasma membrane Na+ channels in the developing brain, depending on duration of intermittent hypoxia.
Multichannel Verification System (MVS): A Dual-Dye Ratiometric Photometry System for Performance Verification of Multichannel Liquid Delivery Devices
Authors: Bradshaw John Thomas , Knaide Tanya , Rogers Alex , Curtis Richard
Published: February 2005

Artel has developed the Multichannel Verification System (MVS), a photometric method for verifying the performance of automated multichannel liquid delivery equipment. 1 On the basis of Artel's patented Dual-Dye Ratiometric Photometry method, the MVS determines both the accuracy and precision of each individual channel of a multichannel liquid delivery device. The MVS verifies aqueous volumes of 2–200 μL, produces results that are traceable to national standards, and can be applied to a wide range of instruments. It is important that the MVS is a robust system that is convenient to use in the laboratory environment so that the volumetric performance of automated liquid-handling equipment can be verified frequently without causing unnecessary delay in use of the instruments for their intended applications.
Low Temperature Microplate Station
Authors: Riedel T. E. , Cox J. C. , Ellington A. D.
Published: February 2005

The automation of biological laboratory assays may require lengthy incubations of reagents on the work surface of a pipetting robot. Commercial devices are readily available for keeping these reagents accessible and warm, but there are few existing technologies for storing accessible reagents below the freezing point of water. Here, we introduce a low cost, small footprint, robot accessible reagent cooler, based on compressor technology capable of acting as an enzyme freezer or extreme cold reagent storage device.
Development and Qualification of an Automated Workcell That Includes a Multicapillary Zone Electrophoresis Instrument
Authors: Neel Tanguy Le , Caillet Christine , Morin Delphine , Baudiment Cecile , Pegon Yves , Truchaud Alain
Published: February 2005

A new multicapillary zone electrophoresis instrument, the Capillarys, was recently launched by Sebia Company. We integrated the Capillarys in an automated workcell that is able to pick tubes from a sample transportation system and arrange them in the right position for bar code reading on the racks of the Capillarys. The racks are transported and loaded on the Capillarys by the robot. After analysis, racks are automatically collected and transferred to a stacker, to wait for storage, waste management, or transportation to another instrument. We built a prototype, and to validate the workcell, we performed a Qualification Plan. The various tests did not reveal important errors in the design of the prototype, but some slight defects in safety, materials, and software were identified. The final decision was to validate the Qualification. The method of Qualification was found to be very efficient for evaluation of the prototype and early detection of necessary improvements. As a result, the risk of modifications required in customer laboratories was limited.
An Ultrarapid Method of Creating 3D Channels and Microstructures
Authors: Mensing Glennys , Pearce Thomas , Beebe David J.
Published: February 2005

We present a method of creating three dimensional microfluidic channel networks and freestanding microstructures using liquid phase photopolymerization techniques. The use of liquid phase microfabrication facilitates the creation of microstructured devices using low-cost materials and equipment. The ability to add multiple layers allows for complex geometries and increases the functional density of channeled devices. The multilayer technique provides a method of interconnecting layers or combining separate layers to form a truly integrated multilayered microfluidic device, as well as a means of forming multilayered freestanding structures. Because this method is based on the fundamentals of microfluidic tectonics (μFT), all components (valves, mixers, filters) compatible with μFT can be integrated into the multilayer channel networks.
TEENAGE BIRTHS AND FINAL ADULT HEIGHT OF MOTHERS IN INDIA, 1998–1999
Authors: BRENNAN LANCE , McDONALD JOHN , SHLOMOWITZ RALPH
Published: February 2005

This paper investigates the statistical association between teenage births and the physical growth path of these mothers. It draws on data on the height of ever-married women aged 15–49 and their birth histories collected in India’s National Family Health Survey in 1998–99, and shows that there was a negative relationship between final adult height of women and the number of births they had as teenagers. Using multiple regression analysis, it is shown that this negative relationship is robust to confounding factors such as standard of living, urban–rural residence, state of origin in India and age of the women.
BIOSOCIAL CORRELATES OF STATURE IN A BRITISH NATIONAL COHORT
Authors: MASCIE-TAYLOR C. G. N. , LASKER G. W.
Published: February 2005

Analyses of height variation using the 1970 UK national cohort study (12,508 children at age 10 and 5470 at age 16) found clear evidence that children of higher socioeconomic status (as measured by social class, crowding, tenure, type of accommodation, income and receipt of government financial assistance) were on average taller than children of lower socioeconomic status but there was little or no difference in average stature between children living in urban or rural areas. Significant differences in height remained for most of the variables after removing the effects of father’s social class suggesting that reliance on social class per se to explain height variation is inadvisable.
‘Feeling of absolute dependence’ or ‘absolute feeling of dependence’? A question revisited
Authors: FINLAY HUESTON E.
Published: February 2005

The translation of Schleiermacher's key phrase ‘das schlechthinnige Abhängigkeitsgefühl’ is a matter of some contention. It has been suggested that the traditional translation (‘feeling of absolute dependence’) is in fact inaccurate and that it should be replaced with the accurate ‘absolute feeling of dependence’. This change would have serious implications for our understanding of Schleiermacher's theology. This essay examines the case for and against a change of translation. It concedes that the change is demanded if one strictly adheres to the rules of grammar but that there are several reasons for putting those rules to one side and holding firm to the traditional translation.
War and Political Violence in Twentieth-Century Europe
Authors: KERSHAW IAN
Published: February 2005

This article takes the obvious link between war and political violence in twentieth-century Europe to ask three questions. Did the cause of such a massive upsurge in violence have roots extending beyond the technologies of modern warfare? What shapes the relative propensity of states and societies towards violence? And what is specifically ‘modern’ (other than the technology of destruction) about mass killing in the twentieth century? It finds answers in the use of popular sovereignty to justify unprecedented ethnic conflict, in a mix of ingredients linked to political culture and contested state legitimacy, and in the role of bureaucracy and technology in the orchestration of large-scale and state-sponsored violence.
Reply to Smith
Authors: KERSHAW IAN
Published: February 2005

I thank Steve Smith for his characteristically thoughtful and shrewd comments on my piece. And I am glad to note that he finds himself ‘in broad agreement’ with what I wrote.
Evidence for CH4 7.6 μm non‐local thermodynamic equilibrium emission in the mesosphere
Authors: López‐Puertas M. , Koukouli M. E. , Funke B. , Gil‐López S. , Glatthor N. , Grabowski U. , von Clarmann T. , Stiller G. P.
Published: February 2005

We present unequivocal evidence for CH4 7.6 μm non‐local thermodynamic equilibrium (non‐LTE) mesospheric emissions as measured by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) experiment on board the ESA Envisat satellite. We have employed non‐LTE radiative transfer models, already used and validated in studies of other atmospheric gases, in order to quantify the magnitude and extent of the CH4 non‐LTE deviation in the Earth's atmosphere. The observed daytime enhancement signatures apparent in the measured radiances cannot be attributed to enhanced daytime temperatures and/or CH4 abundance variations and are reproduced successfully with a dedicated CH4 non‐LTE radiative transfer model. We conclude that, depending on the upper stratospheric/mesospheric temperature structure, the departure from LTE might commence at an altitude as low as 45 km, reaching limb radiance deviations of 20% at 60 km and quickly rising up to 60% at 70 km, for the 7.6 μm CH4 lines.
GFP—PCNA as an S‐phase marker in embryos during the first and subsequent cell cycles
Authors: Kisielewska Jolanta , Lu Pin , Whitaker Michael
Published: February 2005

Background information. Proliferating cell nuclear antigen (PCNA) is a key component of the DNA replication machinery involved in the process of DNA elongation, recombination, methylation and repair. We have used PCNA fused with green fluorescent protein (GFP—PCNA) as a convenient tool to show the progress of S‐phase in single embryos in vivo. Here we make a comparison between Hoechst 33342 and GFP—PCNA as in vivo event markers for DNA synthesis. Hoechst 33342 and DAPI (4,6‐diamidino‐2‐phenylindole) have been used as a simple and rapid method for assessing membrane permeability and staining DNA in mammalian cells. However, it is difficult to use these dyes in living embryos during cell cycle progression studies over long periods of time as they are phototoxic. Moreover, though Hoechst staining reveals nuclear morphology, it gives no information about the progress of S‐phase.

Results. We have microinjected or expressed a GFP—PCNA chimera to develop a method which enables visualization of S‐phase in sea urchin and Caenorhabditis elegans embryos during the first and subsequent embryonic cell cycles and in Drosophila stage 4 embryos during syncytial nuclear divisions. We find that nuclear accumulation of GFP—PCNA correlates with S‐phase onset. Loss of the chimera from the nucleus occurs when the nuclear envelope breaks down at mitosis.

Conclusions. GFP—PCNA is a accurate and non‐toxic marker of S‐phase in embryos during early development.
Volume expansion and plasma protein clearance during intravenous infusion of 5% albumin and autologous plasma
Authors: HEDIN Annika , HAHN Robert G.
Published: February 2005

Autologous plasma may be used to replace plasma volume and plasma proteins during surgery, but its effectiveness is largely unknown. In the present study, the characteristics of predonated frozen and thawed autologous plasma were compared with those of 5% albumin in 15 male volunteers who received 10 ml/kg of body weight of these colloids as intravenous infusions over 30 min. Venous blood was sampled and urine was collected over 8 h to outline the volume expansion and blood–interstitial fluid space transport of three plasma proteins (albumin, fibrinogen and antithrombin) by means of mass balance analysis. The maximum plasma dilution of 5% albumin and autologous plasma averaged 17 and 21% respectively, and their half-lives were 2.5 and 2.9 h respectively (P<0.03). The between-subject variability in dilution was most pronounced for autologous plasma. Transport of protein from blood to the interstitial space occurred faster when the infused fluid contained the protein in question. The rate was highest at 60 min, and the process was still in progress at 8 h when approx. 60% of the infused albumin, 45% of the fibrinogen and 75% of the infused antithrombin had been translocated to the interstitial fluid space. In contrast with the proteins, excess plasma water was removed by urinary excretion. It is concluded that the volume expansion is equivalent for the two colloid fluids, although it is more predictable for 5% albumin. The transport of protein outlasted the volume expansion.
New Flash Illumination Unit
Authors: Bardócz Á. , Klatsmányi Á.
Published: February 2005

A new type flash illumination unit for use with flash tubes, electric sparks, and exploding wires is described. The system is controlled by a thyratron tube, however, in a manner different than up to now; the controlled energy does not pass through the thyratron tube. The basic circuit of the apparatus consists of two flash tubes or spark gaps connected in series. The flash tubes or spark gaps are ignited by giving double voltage first to the one and, when it is ignited, to the other spark gap or flash tube by means of the thyratron tube. The flash tube illumination circuit makes the simultaneous operation of more than two flash tubes or sparks possible. The thyratron tube igniting the illumination unit may be controlled by electric or by mechanical means.
Liquid Hydrogen Bubble Chambers
Authors: Parmentier Douglas , Schwemin Arnold J.
Published: February 2005

Chambers 2½ inches and 4 inches in diameter have been constructed of brass with pyrex ports and sealed with lead-wire gaskets. Metal walls and a copper heat leak eliminate the need for a surrounding pressurized bath. The required fast-pulsing techniques and use of a heat regenerator are described in detail. Schematic diagrams show the chambers, pressure- and temperature-monitoring devices, and illumination method, and photographs of typical tracks and events are included.
Potassium Iodide Fast Neutron Detector
Authors: Brown Bernard
Published: February 2005

A fast neutron detector has been developed consisting of powdered thallium activated potassium iodide dispersed in polystyrene. Recoil protons from the polystyrene are detected by potassium iodide. The detection efficiency of the potassium iodide detector for radium-beryllium neutrons is comparable to that of zinc sulphide dispersed in polystyrene. Potassium iodide has a longer decay time than zinc sulfide, permitting ``phoswich'' coincidence arrangements. The energy response of the potassium iodide detector is closer to the energy response of a thick hydrogenous radiator than that of a zinc sulfide detector.
Some Devices for the Stark Modulation Millimeter-Wave Spectrograph
Authors: Okaya Akira
Published: February 2005

High sensitivity and wide-band frequency characteristic for a microwave spectrograph are required for the detection of weak absorption lines and for researches on the hyperfine structures of the spectral lines of free molecules in the millimeter wave range. In order to improve the important components of spectrograph, the author has designed a low-loss K-band Stark cell, a frequency multiplier of wide-band frequency character, a Wheatstone bridge-type triode lock-in detector and a compact square wave generator. The overall sensitivity of the spectrograph using these elements was about 5×10−8 cm−1 in the 6 mm wave range. Thus, the author has succeeded in detecting new spectral lines [J. Phys. Soc. Japan 9, 135 (1954)] of CH2O and in observing their new magnetic hyperfine structures (to be published).
High-Resolution Magnetic Spectrometer
Authors: Rubin S. , Sachs D. C.
Published: February 2005

A 180° point-focusing magnetic spectrometer was constructed for high resolution analysis of the momentum distribution of protons up to 2 Mev in energy. Mechanical adjustments of the poles enabled the field shape to be empirically adjusted for minimum radial aberration in the focal plane. The aperture is 0.0025 steradian, and the momentum resolution is better than 2000.
Method for Maintaining Level of Liquefied Gas Refrigerants
Authors: Goodwin Robert D.
Published: February 2005

Controls are described for maintaining a constant level of liquid nitrogen in a still-head can. A small electric solenoid valve is employed directly in the liquid nitrogen line, operating under the control of a sensitive level switch. The method and associated instruments are described, including a rapid means for changing supply cans.
Magnetic Analysis of Scattered Particles
Authors: Furth H. P.
Published: February 2005

The theory of conditioned probabilities is applied to the problem of momentum, charge, and mass determination from Coulomb scattered tracks in a magnetic field. An optimum procedure is derived, which makes use of both random and systematic track curvature.

It is shown that application of this procedure to a highly relativistic nuclear emulsion track of 1-cm length in a field of 300 000 gauss will yield the momentum information of a 9.2-cm track in zero field. If the scattering information were neglected, the effective length of the track would be 8.2 cm. At 100 000 gauss, the improvement in effective track length due to the inclusion of scattering information is shown to be by a factor of 2.3.
Null Reading Flip-Coil Fluxmeter
Authors: Fechter H. R. , Rubin Sylvan
Published: February 2005

Two flip coils are rotated through 180° to give a precision measurement of the ratio of separate magnetic fields. The output voltages are connected in opposition and balanced in a resistance potentiometer using a sensitive galvanometer as a null indicator. The ratio of the fields is a linear function of the potentiometer setting. In fields of several thousand gauss and using a common shaft for the coils, readings were reproducible to within 0.01%. With separate selsyn motor drives the precision was 0.02%.
Focusing Atomic Beam Apparatus
Authors: Lemonick Aaron , Pipkin Francis M. , Hamilton Donald R.
Published: February 2005

The construction and design principles of a focusing atomic beam apparatus are reported. This apparatus, which is of the radio-frequency magnetic resonance type and which has been used to measure the spins and hyperfine splittings of four radioactive nuclides as reported elsewhere, utilizes the six-pole focusing magnet of Friedburg and Paul and of Korsunskii and Fogel but in a way which avoids velocity aberrations. From an analysis of the optimization of intensities in the conventional and the focusing types of atomic beam apparatus it is concluded that the latter has an advantage of a factor of roughly twenty-five.
Simple Ultraviolet Radiometer
Authors: Stern Sidney C. , Hill Charles W.
Published: February 2005

This paper describes in some detail a radiometer for measurement of ultraviolet radiation from sun and sky. As designed, the instrument is selectively responsive to a narrow band of wavelengths and is capable of detecting and measuring low-energy levels. The radiometer consists of a photoelectric sensing element, an ultraviolet transmitting window, and a dry-cell battery mounted in a small housing. Calibration of the instrument shows satisfactory agreement with Lambert's cosine law and a linear relationship between energy flux and output of the phototube. For recording the signal from the radiometer the output is fed to a direct current amplifier which in turn drives a recorder. A typical recording for a cloudy day is presented.
Millimicrosecond Timing with Large Scintillation Detectors
Authors: Keuffel J. W. , Sandmann W. H. , Stitt R. K.
Published: February 2005

The timing precision attainable with large liquid scintillation detectors has been studied. Such detectors have slow rise-times (∼10−8 sec) compared with those used in conventional nuclear physics timing experiments. The rise-time is a result of photon time of flight and transit time in the larger, slower photomultipliers (such as the Dumont 6364) which must be used for good light collection. However, timing errors due to rise-time may be largely overcome when dealing with large, statistically smooth pulses such as are encountered in cosmic-ray experiments with unstable particles. A simple correction based on the pulse height is applied to each time measurement. Using this technique a timing error curve is obtained with a standard deviation of 1.6 mμsec for a large detector using a Dumont 6364.
Reflected Beam X-Ray Monochromator for Geiger Counter Diffractometry
Authors: Banerjee Bani R.
Published: February 2005

A bent crystal monochromator, for Geiger counter diffractometry, was constructed to monochromate the specimen-reflected x-ray beam. This results in very low backgrounds, due to the elimination of fluorescent scattering from the specimen. Adequate resolution and diffracted energy were obtained.
Stroboscope Polarimeter
Authors: Landegren G. F.
Published: February 2005

An apparatus for measuring optical rotation produced by optically active substances is described in which light, after passing through a continuously rotating Polaroid disk, carrying a degree scale, then goes through a stationary Polaroid disk and is incident as sinusoidally modulated light upon a phototube, causing it to produce a signal (of audio-frequency twice that of the frequency of rotation) which is then passed through an audio-amplifier and fed to a stroboscope, directed on the rotating disk, which thereby flashes in synchronism with the signal, and hence also with the rotation of the disk. By adjusting the angular position of the stationary disk, the zero mark on the rotating disk is made to appear to coincide with a stationary fiducial mark. When an optically active sample is interposed between the polaroid disks, there is a phase shift in the modulation of the light which causes a reading, as observed in stroboscopic light, on the rotating disk equal to the angular rotation produced by the sample.
Experience with Piston-Cylinder Balance for Pressure Measurements
Authors: Reamer H. H. , Sage B. H.
Published: February 2005

A piston-cylinder balance has been found to be a satisfactory means of measuring pressures. Laboratory experience over a fourteen-year period in the use of such an instrument suitable for measurements up to 10 000 pounds per square inch, is presented. It was found that over a period of ten years the calibration changed by less than four parts in 10 000. This small change in calibration during nearly continuous service of the apparatus is an indication of the suitability of piston-cylinder balances for routine measurements.
Constant Flow-Rate Circulating System
Authors: Shapiro I. , Landesman H.
Published: February 2005

A circulating pump designed to give a constant rate of flow of gases, even at sub-atmospheric pressures, is described. The pumping mechanism consists of a reciprocating piston in a cylinder driven at a constant linear speed. The valves in a double-acting valve system have been made ``weightless'' by the use of solenoids. Mercury is used as a displacement fluid.
Ultra-High Vacuum Valve
Authors: Bills D. G. , Allen F. G.
Published: February 2005

An all-metal ultra-high vacuum valve is described. The valve has a continuously variable conductance from about 1 l/sec to less than 10−14 l/sec and presumably as small as desired. An equilibrium method of measuring small leakage conductances is described.
High-Sensitivity Photoconductor Layers
Authors: Thomsen S. Milton , Bube Richard H.
Published: February 2005

High-sensitivity photoconductor ``powder'' layers and ``sintered'' layers have been prepared in large-area form, with most of the desirable characteristics of single crystals. The methods involved in the preparation of these layers are simple and avoid the difficulties involved in growing large-area single crystals, or in producing large-area photoconductors by evaporation in vacuum. Both types of layers can be made into photocells of any desired area, by providing suitable electrodes. At an illumination of 1 ft-c, ratios of photo-current to dark current as large as 106 may be obtained for both types of layers. A two-inch square cell made from either a powder or a sintered layer can pass an ampere for an illumination of a few foot candles. In addition to their ease of fabrication, the new layers also have advantages in the large increase in red sensitivity obtainable with cadmium sulfide, and in the ohmic character of sintered layers with silver-paste electrodes.
Alternating-Gradient Channel Using Permanent Bar Magnets
Authors: Stubbins Warren Fenton
Published: February 2005

An alternating-gradient channel for containing relativistic electrons (7 Mev) is made by arranging sets of four permanent bar magnets along an evacuated tube. The resultant field from each set is calculated assuming point magnetic poles. Four configurations for the magnet sets are considered and the criteria for retaining and focusing the electron beam are established for each configuration by matrix analysis of the equations of motion of the electrons in the periodic magnetic fields. These equations relate the magnetic pole strengths, the set positions, and the electron energy ranges permissible for each case. The aperture of the configuration is indicated, and experimental results are given.
Thirty-Six-Atmosphere Diffusion Cloud Chamber
Authors: Elliott John B. , Maenchen George , Moulthrop Peter H. , Oswald Larry O. , Powell Wilson M. , Wright Robert W.
Published: February 2005

A 36-atmosphere diffusion cloud chamber has been constructed for use with the 184-inch cyclotron and with the bevatron. Minimum-ionizing particles leave dense, sharp tracks of good contrast with hydrogen filling at design pressure. In the operation described, one event is obtained every 15 minutes for a reaction cross section of 30 mb for negative pions on hydrogen. Among the unique features of the chamber are (a) the high pressure; (b) the high magnetic field; (c) the simple unit preassembly of the chamber and the upper pole piece; (d) the distortion-free photography afforded by the small camera windows of good optical quality directly in front of the camera lenses and the absence of a large top glass near the sensitive region; (e) the thin window for collimated beams; (f) the supported cast Astrolite windows for illumination; and (g) the satisfactory sensitive layer obtained despite the large height-diameter ratio of the pressure vessel.
Calorimetry of High Polymers. III. A New Type of Adiabatic Jacket and Calorimeter
Authors: Worthington A. E. , Marx P. C. , Dole Malcolm
Published: February 2005

This paper describes a new type of adiabatic jacket and a modified calorimeter designed especially for the measurement of the specific heats of high polymers in the range −20 to +300°C. New features of the adiabatic jacket include the use of two dissimilar metals to increase temperature uniformity and a new method of closing and controlling the temperature of the ends. Calibration data using Al2O3 had an average precision of ±0.07 percent, although the uncertainty in an individual measurement, while ±0.1 percent up to 160°C. may reach ±0.5 percent at 300°C. Further studies of the use of an alternating current watthour meter in calorimetry are reported.
Cloud Chamber for Precision Measurements
Authors: Fretter W. B. , Friesen E. W.
Published: February 2005

A cloud chamber has been constructed in which accurate measurements of ionization and momentum can be made simultaneously. The chamber has a useful volume of 18 in. by 12 in. by 5 in., contains helium, and is in a magnetic field of 7500 gauss. Procedures have been developed to measure momentum and ionization and to determine the errors. Measurements on 40 protons indicate an average probable error of 7 percent for an individual measurement of mass by the comparison of ionization and momentum. A calibration technique is used for the determination of the minimum ionization for each case.
Multiple-Bridge Circuits for Measurement of Small Changes in Resistance
Authors: Warshawsky I.
Published: February 2005

In the multiple-bridge circuit, first-order effects of random resistance variations occurring at the junctions of a Wheatstone bridge are eliminated by an extension of Kelvin's method, which involves adding an auxiliary resistor pair at each bridge corner at which the variations occur. The remaining second-order error, and the effects of thermals, are evaluated. The multiple-bridge technique makes possible precise resistance comparisons, and the accurate measurement of small changes in resistance of an element that is connected through switch contacts, or brushes and sliprings. Some numerical design data are given. Elaborations of the basic circuit, and typical applications, including measurements with resistance strain gauges, are described.
Second-Order Aberrations in Sector Shaped Electromagnetic Analyzers
Authors: Voorhies H. G.
Published: February 2005

The expressions for the second-order velocity aberration and the second-order angle-velocity aberration are given for a sector shaped electromagnetic analyzer with superimposed electric and magnetic fields. Focusing is in one plane.
Some Properties of Light Guides
Authors: Ettinger George M.
Published: February 2005

In some scintillation counter applications it is impracticable to place the photomultiplier tube in close proximity to the scintillation crystal; light guides are therefore employed. These guides produce considerable attenuation, so that photomultiplier signal-to-noise ratio becomes low. Factors affecting attenuation in light guides are mentioned in this paper; in particular, the effects of various preparations of the guide surface are considered.
Design and Construction of Two Low-Temperature Thermostats
Authors: Gilchrist Andrew
Published: February 2005

Two small thermostats for use in the temperature ranges −40°C to −70°C and −70°C to −150°C are described. The controlling element in both cases is a thermocouple used in conjunction with a potentiometer and galvanometer-photomultiplier amplifier. The higher-temperature thermostat uses an acetone bath as the immersion medium while the lower temperature one uses a metal block for this purpose.

Temperature control to within 0.01°C may be attained with both thermostats if reasonable care is taken in correcting for the normal drift in the potentiometer calibration which occurs over periods of time greater than an hour.
Micromanometer for Measuring Boundary Layer Profiles
Authors: Smith A. M. O. , Murphy James S.
Published: February 2005

A micromanometer is described which satisfies the requirements for measuring laminar or turbulent boundary layer profiles in incompressible flow. It is a design based on the U-tube principle and has a demonstrated accuracy of ±0.0002 in. H2O for pressure differentials less than 0.8 in. H2O and ±0.001 in. H2O for measurements in the range 0.8 to 24 in. H2O. The lag time of the instrument is small, resulting in economical use of testing time. Results of experiments to find an optimum manometer fluid and the manometer accuracy are included. Measurements of temperature effects show good correlation with theory. Typical boundary layer profiles measured with the micromanometer exhibit a high degree of consistency and lack of scatter.
Nomographs for the Determination of Wavelength for Highest Angle X-Ray Diffraction
Authors: Muldawer L. , Feder R.
Published: February 2005

A single operation technique is presented for the determination of wavelength for highest angle diffraction of cubic materials. This method makes use of a chart with the lattice parameter as ordinate and (λ/2 sinθ) as abscissa, lines being drawn for each (h2+k2+l2).

For noncubic materials, a chart is prepared with lattice spacing as ordinate and (1/sinθ) as abscissa, lines being drawn for each wavelength. Separate settings must be made for each spacing in this second case.
Cryostat for Cyclotron Irradiation at Liquid Helium Temperatures
Authors: Mapother D. E. , Witt F. E. L.
Published: February 2005

A description is given of a cryostat which has been developed for cooling small specimens with liquid helium while they are subjected to irradiations of several days duration in a cyclotron beam. The cryostat is fabricated for the most part from commercially available sheet-metal parts and consists essentially of a liquid helium vessel shielded by a liquid nitrogen cooled envelope. The intrinsic loss rates for refrigerants with this apparatus are about 5 liters per day of liquid nitrogen and 600 cc of liquid helium per day, but considerably larger loss rates are encountered during periods when the cyclotron beam is on. The performance of the cryostat during irradiation experiments is discussed.
Fast Coincidence System with Amplitude Discrimination and Accidentals Monitoring
Authors: Stanford G. S. , Pieper G. F.
Published: February 2005

A coincidence system with a short resolving time, variable up to 120 millimicroseconds, has been developed for use in (α, pγ) and (d, pγ) correlation investigations. The system is a ``slow-fast'' one in that amplitude selection in both channels is made before the pulses reach the fast coincidence circuit, while accurate timing is achieved by parallel delaying and sharpening networks in each channel. The advantage of the slow-fast method is that it permits the inclusion in a simple way of an accurate monitor for accidental coincidences, thus allowing continuous accidentals monitoring while an experiment is in progress. A description of the whole system and details of new circuits and special components are given.
Deflection Multiplier for Reflecting Galvanometers
Authors: Dauphinee T. M.
Published: February 2005

A very simple multiple reflection system is described by which the effective sensitivity of a reflecting galvanometer can be increased by a factor of five or more without increasing the mirror to scale distance. The full width of the galvanometer mirror is used for each reflection, so that with a good quality mirror there is little reduction in the sharpness of the hairline image and only moderate reduction in the brightness of the spot. Use of a 2-m path distance and four or five reflections makes it possible to extend the useful sensitivity of a sensitive galvanometer close to the limit set by Brownian movement. The principle of this amplifying system can be applied directly to most forms of optical lever.
Automatic Balance for Measurement of the Strength of Glass Fibers
Authors: Sinclair David
Published: February 2005

The semiautomatic balance used to measure the tensile strength and Young's modulus of glass fibers when bent into a loop has been made fully automatic. A differential transformer and servomotor are used to apply chain-weight as the tension in the looped fiber is increased by the loading motor.

All measurements needed to calculate the tensile strength and Young's modulus are automatically recorded on the drum chart driven by the loading motor. The maximum tensile stress in the looped fiber at the instant of break is proportional to the vertical motion of the recording pen, and the maximum strain is proportional to the rotation of the drum.
Continuous Recording of the Growth of Micro-Organisms under Turbidostatic and Chemostatic Control
Authors: Anderson Paul A.
Published: February 2005

The microbial auxanometer, an instrument which automatically records the growth rate of a micro-organism during its continuous growth under turbidostatic control, has been developed further to provide (1) interchangeable turbidostatic and chemostatic control, (2) automatic recording of culture density under chemostatic control or during uncontrolled growth, and (3) improvements in growth tube design which reduce cell trapping. The instrument delivers a continuous record of the growth history of the organism under either free-growing or growth-factor-limited conditions and of changes in growth rate induced by physical or chemical means. It is well adapted to the study of spontaneous and induced mutation rates.
Ballistocardiographic Instrumentation
Authors: Lewis H. W. , Smith DeWitt H. , Lewis M. R.
Published: February 2005

An analog method is described for solving some of the mechanical problems associated with the recording of ballistocardiograms. An L-C-R circuit is used as the analog of the body coupled to a fixed table. It is concluded that no technical obstacles exist to the widespread use of ballistocardiography, through equipment similar to that described here. Clinical problems in the interpretation are not discussed.
Image Curvature Caused by Fringing Fields in Magnetic Sector Mass Spectrometers
Authors: Berry Clifford E.
Published: February 2005

The fringing field of a magnetic sector analyzer produces a curved image of a line object. This is because rays off the median plane traverse a slightly different fringing field from that traversed by those on the median plane. In this paper, the shape of the image is calculated for a general paraxial ray traveling in a plane inclined to the median plane, under the assumption that the fringing field is two-dimensional. It is found that the image is not only curved, but is broadened by an amount depending on the exact nature of the fringing field. In the special case in which all paraxial rays travel in planes parallel to the median plane, and in which the analyzer is symmetrical, a straight-line object is imaged in a line having a radius of curvature of R/2, where R is the sector radius. In this special case, the shape of the image is independent of the exact nature of the fringing field.
High Temperature X-Ray Diffraction Camera
Authors: Austin A. E. , Richard N. A. , Schwartz C. M.
Published: February 2005

A high-temperature x-ray powder diffraction camera has been designed and constructed. The design specifications were as follows: (1) to permit operation at temperatures up to at least 2000°C, in a high vacuum, (2) to be able to work in controlled atmosphere at somewhat lower temperatures, and (3) to permit successive exposures of the specimen held at temperature. The completed apparatus appears to meet these requirements.
Field Homogeneity and Pole Distribution
Authors: Bjorken J. D. , Bitter F.
Published: February 2005

The design of a magnet for producing a uniform field is described. The magnet model used in the calculations is that of cylindrical cores surrounded by rims. The positions of the central pole faces and rims can be adjusted independently. A calculation, based on the assumption that the pole pieces are uniformly magnetized, shows that, for a certain positioning of the cores and rims, the z2 and z4 correction terms to Hz can be simultaneously canceled. Practical limitations to uniformity that result from a slight asymmetry in the geometry and from the effect of nonuniformity in magnetization because of domain structure in the iron also are discussed.
Glass Resistor for Use in Vacuum Systems
Authors: Sloan Larry G.
Published: February 2005

This article describes the construction of a conductive glass resistor intended for operation in a sealed high vacuum system. The resistor is small, having a body size of 0.195 in. long and ⅛ in. diameter, and resistance values from 0.25 to 15 megohms can be achieved. A power dissipation of 25 milliwatts is normal and in vacuum, the operating temperature is approximately 65°C. After suitable initial outgassing, no appreciable amount of gas is evolved into the vacuum system as a result of operating the resistors.
Dekatron Drive Circuit and Application
Authors: Graham M. , Higinbotham W. A. , Rankowitz S.
Published: February 2005

A reliable, one-tube drive circuit for decade glow transfer counter tubes is described. Application of the circuit is illustrated in a ten-channel glow tube register with automatic electric typewriter readout.
Anisotropic Projector
Authors: Leighton Robert B.
Published: February 2005

An optical projector having different magnifications, 5× and 50×, in two rectangular directions is described. Although the device is designed principally for rapid measurement of cloud-chamber track curvatures, it has been applied to various situations in which plane-to-plane imaging at constant magnification is desired. Simple plano-convex cylindrical lenses are used as the image-forming elements. These give quite satisfactory linearity and resolution at the maximum magnification.
High-Speed Light Pulse Shaper using a 5000 RPS Rotating Mirror
Authors: Cladis John B. , Jones Clarence S. , Wickersheim Kenneth A.
Published: February 2005

A light pulse generator is described which utilizes a flash lamp and a 5000 revolutions per second rotating mirror. A variety of light pulse shapes can be produced having widths from 1.16×10−9 seconds to 10−6 second.
Narrow Pass Band Albedometer
Authors: Ashburn Edward V. , Pentoney C. P. , Hohanshelt Z. W. , Weldon R. G.
Published: February 2005

An albedometer is described that has the incident radiations entering an integrating sphere instead of falling directly upon a horizontal receiver, as in the albedometers that have been used in the past. In this new albedometer the receiver looks at a small opal glass window in the sphere. Filters with a narrow pass band may be placed between the window and the receiver. This arrangement makes it possible to determine the variation of albedo with wavelength.
Double-Crystal Spectrometer Attachment to the Wide-Range Goniometer of the Norelco X-Ray Diffractometer
Authors: Maloof S. R.
Published: February 2005

The design of a double-crystal spectrometer attachment to the Norelco wide-range goniometer is described. The outstanding features of this design are: (1) the axes of rotation of both crystals are made parallel in the construction of the instrument; (2) one can easily align the instrument in the parallel (n, -n) or antiparallel (n, +n) setting in less than one hour; and (3) no modification of the Norelco equipment is needed, and good use is made of the wide-range goniometer for setting the first crystal at the proper Bragg angle for reflection. Typical parallel position rocking curves for single-crystal germanium and silicon are presented.
Bolometer Detection of Nuclear Quadrupole Resonance
Authors: Robinson Hugh G.
Published: February 2005

The possibility of using bolometer detection for quadrupole resonance is investigated. Preliminary results in the 30 Mc region indicate that such a detection method can be made to operate easily and at a sensitivity comparable to conventional regenerative detectors. Scaling to other frequencies should be possible without the difficulties encountered in regenerative and super-regenerative detectors.
Production and Use of High Transient Magnetic Fields. I
Authors: Furth H. P. , Waniek R. W.
Published: February 2005

Experiments involving pulsed magnetic fields of a half-megagauss and more are shown to be practical. Some basic concepts are developed regarding the construction of impact resistant solenoids and the selection of the appropriate power supply. Operation of various high-field magnets in the pulse range 50 to 10 000 μsec is discussed, and some techniques for associated solid state experiments are given. Magnetoresistance measurements up to 600 000 gauss have been made for germanium. Operation of a 175 000 gauss Helmholtz-type magnet for nuclear track plate work with the 95-Mev Harvard synchrocyclotron is described.
New Timing Method for Scintillation Events in Fast Coincidence Experiments
Authors: Weinzierl Peter
Published: February 2005

The output pulses from scintillation detectors are amplified in conventional feedback amplifiers and transformed into a bipolar wave form, which passes the discrimination level of the following EFP 60 trigger circuit at a given time after inception of the scintillation pulse, independent of its amplitude within a wide range. If these standard pulses are shaped and fed into a fast coincidence circuit, even for NaI(Tl) resolving times of the order of 10−8 sec can be obtained. The main limitation of the method is due to time jitter of the standard pulses caused by statistical fluctuations of the rising edge of the photomultiplier pulses which results in a reduction of coincidence efficiency.
Nuclear Induction Spectrometer for Use at High rf Intensities and Low Temperatures
Authors: Redfield Alfred G.
Published: February 2005

A nuclear induction spectrometer for the measurement of short relaxation times and the study of saturation and related phenomena is described. Radio-frequency intensities of up to 10 gauss are attainable from four to ten megacycles. Novel features of the apparatus are an rf head for use in a liquid helium cryostat, transmitter output level stabilization circuit, and a calibration circuit for comparing the intensity of the absorption at different rf levels.
Response Function of NaI(Tl) Scintillation Counters
Authors: Berger Martin J. , Doggett J.
Published: February 2005

The response function of NaI(Tl) scintillation detectors for gamma radiation has been calculated by the Monte Carlo method. Summary results of this calculation are presented in terms of the photofraction, i.e., the ratio of the area under the photopeak to the total area of a scintillation spectrum. Values of the photofraction are given for collimated monoenergetic radiation with energies between 0.279 and 4.45 Mev incident centrally on the endface of cylindrical crystals ranging in size from 0.25 in. (radius)×0.5 in. (length) to 2.5×9 in.