Intensive Data Collection Research Articles

Mesoscale variations in summer winds over the Cape Columbine — St Helena Bay region, South Africa

Spatial and temporal variations in the near-surface wind field and their relation to upwelling in the lee of the Cape Columbine headland were investigated during the summers of 1979–1980. Time series of meteorological data were collected at an automatic weather station situated on the northern tip of the headland. Intensive data collection by means of pilot balloons and hand-held sensors permitted description of thermally-driven wind oscillations and, on a larger scale, gradient wind cycles during January and February 1979. Results of aerial surveys were used to document wind shear and upwelling over St Helena Bay in November and December 1980. Synoptic weather systems further south controlled the depth and trajectory of wind flow. During cool westerly flow, homogeneous patterns prevailed with limited Seabreeze enhancement along the coast north of St Helena Bay. The prevailing equatorward wind was concentrated in a "jet" over the Cape Columbine headland. This wind jet reached maximum intensity in the 100–300 m layer just before sunset at 19h00, fanning out and decelerating with cyclonic curvature downstream over St Helena Bay. The influence of these mesoscale variations in wind stress is spatially correlated to coastal upwelling patterns in case studies.

Crystal and molecular structure of 6- C-(2-furyl)-1,2:3,4-di- O-isopropylidene-α- d- glycero- d- galacto-hexopyranose

6- C-(2-Furyl)-1,2:3,4-di- O-isopropylidene-α- d- glycero- d- galacto-hexopyranose ( 1) has been investigated by X-ray diffraction methods. The crystals obtained from ethyl acetate-light petroleum were monoclinic, space group P2 1 ( Z = 2), with cell dimensions a = 13.796(2), b = 7.887(1), c = 8.035(1) Å, and β = 106.68(3)°. A four-circle, automatic STOE diffractometer was used for the collection of intensity data. Of 1600 reflection intensities, 1390 were of I > 2σ I and were used for refinement. The structure was solved by direct methods, and the atomic parameters were refined by the full-matrix, least-squares procedure, giving R 0.056. The pyranose ring in 1 adopts a hybrid twist-boat conformation (° T 2 + B 2,5).

Reconstruction of Long-Term Time Series for Commercial Fisheries Abundance and Estuarine Pollution Loadings

Time series from 1880–1980 for the commercial landings of 35 species and associated fishing effort were reconstructed for the Hudson-Raritan Estuary, Potomac River, Delaware River, Connecticut River and Narragansett Bay. Time series for the same period were developed for indices representing pollutant loadings, developmental activities and habitat alterations for the five target river basins. These indices included representations of demography, sewage and industrial loadings, habitat factors, and nutrient, carbon, and sediment inputs. These data were the result of intensive data collection effort using county, state, and federal records to ascertain activities along individual water basins through time. Direct measures of loadings were used when available, and indirect indicators of loadings were implemented where appropriate. Missing data points from climatic and pollution time series were estimated by statistical modeling, interpolation, and assumption. A probabilistic method was developed to estimate relative stock abundance for each target species-estuary combination using estuarine-specific landings, regional landings, regional catch-by-gear, and regional effort.

Quaternary Period in Saudi Arabia: Volume 2

Owing to rapid socioeconomic growth during the last 2 decades, the development of groundwater resources has been given priority in Saudi Arabia's development program. All through this period there have been intensive field studies, data collection, analyses, and interpretation related to the geology and hydrogeology of the region, the results of which have been presented in the form of tremendous amounts of field notes, maps, and accompanying explanations and regional technical reports written by government experts, university educators, and consulting engineers. This vast amount of available scientific and technological knowledge about geology, geomorphology, climatology, and hydrogeology of Saudi Arabia needs compilation. The authors of the various topics contained in this book have taken the lead in compiling, in an authoritative way, information which is extremely broad and interdisciplinary.

The refinement of unit cell parameters from two-circle diffractometer measurements

Measurements of the crystal rotation angle (ω) for centred reflections provide the most reliable data for the refinement of unit cell parameters in two-circle single-crystal diffractometry. Zero-layer reflections are least affected by crystal misalignment, and can be used in a least-squares refinement of the corresponding reciprocal-cell parameters. The introduction of equations for a general crystal orientation allows the precise refinement of all six cell parameters from measurements of reflections on a range of layers for a misaligned crystal; only one crystal mounting is required. The possibilities of applying the general orientation algebra to intensity data collection are discussed.

単結晶X線回折実験用ガス炎加熱装置と温度測定方法

Gas-flame heating apparatus for X-ray diffraction studies designed by Yamanaka, Takeuchi and Sadanaga (1981) consists of gas flow controller and microburner set on the stand and provides temperatures higher than 2000°C. Control of the temperature of the sample is carried out by varying the mixing ratio of propane, oxygen and nitrogen gases. The last gas plays a role to regulate the heating temperature and to suppress a fluctuation of the gas-flame especially at low temperatures. It has been demanded to improve the microburner for a more applicable usage for the single-crystal X-ray diffraction studies. A newly devised heating system is composed of a joint assembly of gas-flame and electric resistance heater. Since the assembly is set on the χ-circle of a four-circle X-ray diffractometer, measurement of the diffraction intensities can be made throughout the same samplesetting from room temperature to high temperatures up to 2500°C and can be conducted at more stable and highly desired temperatures. The measurement of the sample-temperatures higher than 1500°C is carried out by a thermocouple of Pt-Rh (20-40%) or Ir-Rh (40%) and an optical pyrometer. For the precise temperature measurement during the collection of intensity data, the sample is mounted on the thermocouple attached to the goniometer head. The thermoelectric current is guided to the regulator and recorder through a ring terminal fixed to the goniometer.

The accuracy of retrospective chart review in measuring nosocomial infection rates. Results of validation studies in pilot hospitals.

To measure the accuracy and consistency of a standardized method--retrospective chart review (RCR)--for estimating nosocomial infection rates (NIRs) in individual hospitals, the authors performed a series of pilot studies in four hospitals of different types. In comparison with a standard based on diagnoses made by physician-epidemiologists supervising intensive prospective data collection teams, the RCR method was found to have an average sensitivity of 0.74 (+/- 0.02 SE; range 0.69-0.78) and an average specificity of 0.964 (+/- 0.002; 0.945-0.991). These values were comparable to those of the physician-epidemiologists' diagnoses and varied less among the hospitals. Two independent teams of chart reviewers were found to have similar levels of sensitivity and specificity, and the reliability of diagnosis at the level of the individual chart reviewer averaged 0.94. In a restudy at one of the pilot hospitals at the midpoint of the actual Medical Records Survey (MRS), there was a substantial increase in sensitivityand a slight increase in specificity as a result of improvements made in the RCR method after the original pilot studies.

Analysis of a photographic–vidicon camera method of LEED intensity measurements

Low-energy electron diffraction (LEED) has great need for a quick and efficient means of making intensity measurements (e.g., in studying reactive surfaces which quickly degrade, and in handling the enormous amounts of data needed for data averaging). The photographic-vidicon camera method fills this need. This paper describes a system and procedure for this method. We have pointed out advantages of this method over other methods of LEED intensity data collection and analysis, and have included comments on the advantages of our experimental system over other systems using this method. General properties of the photographic and vicdicon system are analyzed as well as specific tests done on the method. Estimates of probable error in spot intensity measurements due to numerous effects have been analyzed and I-V curves reduced from raw photographic data are compared. It is hoped that the description, comments, and analysis will facilitate the incorporation of the photographic-vidicon method of LEED analysis into research programs.

Environmental Conditions on the Continental Shelf Off West Greenland

This paper describes the meteorological, hydrographical, and ice conditions of the Davis Strait, with particular emphasis on the west Greenland continental shelf, located from 630 to 680 N latitude. An analysis is presented of existing information and environmental data obtained during presented of existing information and environmental data obtained during intensive data-collection programs conducted during the summer and fall of 1975 and 1976. Introduction Until offshore petroleum exploration began in the Davis Strait of west Greenland, little attention had been devoted to environmental conditions of the area. Only limited hydrographic data existed for concession areas located up to 160 km from Greenland's coast, between latitudes 63 degrees and 68 degrees N. Data on ice conditions, the most critical factor of offshore operations in northern waters, also were scarce.To obtain data on currents, icebergs, ice drift, and weather conditions, comprehensive environmental data collection programs were conducted during 1975-76, both by the concessionaires (with Chevron Petroleum of Greenland as operator) and by the Danish Ministry for Greenland. The programs performed by the concessionaires were intended primarily to provide performed by the concessionaires were intended primarily to provide sufficient data for planning and executing drilling operations. These programs were concentrated on the concession areas. The Ministry's test programs were concentrated on the concession areas. The Ministry's test programs also included the possible effects of oil spills on the sensitive programs also included the possible effects of oil spills on the sensitive arctic environment.The government programs for 1975-76 were executed by the Danish Hydraulic Institute (DHI), which also was commissioned to perform the industry's Weathership program in 1976. Special iceberg profiling equipment was used in 1976, in addition to seven wave-rider buoys and 35 "Aanderaa" recording current meters, which were deployed in water up to 600 m deep. The areas involved are shown in Figs. 1 and 2.In addition to these programs, reconnaissance flights and comprehensive analysis of existing "vestis" (west ice) data have been performed by the Danish Meteorological Institute (DMI). Also, wave hindcasting studies and analysis of existing hydrographic data were conducted by DHI.This paper presents a general description of the area's environmental conditions, as well as examples of the data collected during the 1975-76 programs. Environmental programs also were performed for the Ministry for programs. Environmental programs also were performed for the Ministry for Greenland in 1977 and 1978, but are not reported here. Meteorological Conditions General Weather conditions in the Davis Strait are governed by the interaction between the polar high-pressure field over Greenland and cyclones, which normally move eastward from the east coast of Canada and the U.S. Most cyclones pass south of Greenland, but some propagate northward along the east coast of Canada, or through the Davis Strait. Fig. 3 shows examples from pilot charts (U.S. Navy) of cyclone tracks during September and October of 1955 to 1960, inclusive.The barometric polar high pressure is created by cooling air masses over the ice cap in the polar region and Greenland; thus, its extent shows seasonal variations. Because of the polar high pressure over Greenland, the isobars in the Davis Strait often are compressed and aligned north-south along the west coast of Greenland. JPT P. 1381

Research assistantship experiences and subsequent research productivity

This paper is an examination of one component of research training programs, the research assistantship. Data are presented from a national study of the topic. Results of a survey with 3,963 respondents showed that genuine research assistantship experience is positively related to subsequent research involvement and productivity. More intensive data collection from the 50 most productive researchers and 50 nonproductive respondents resulted in identification of 35 variables that discriminate between the two groups (4 structural, 19 experiential, 4 supervisor-assistant interactions, and 8 perceptual). Clusters of variables resulting from factor analysis are presented and nondiscriminating variables are discussed. Recommendations are offered for designers and directors of programs in colleges and universities for use in training educational research personnel.

An improved method for intensity data collection with a computer-controlled diffractometer

An improved method for intensity data collection with a computer-controlled diffractometer

Atomic vibrations and thermal expansion of some silicates at high temperatures

At present improved experimental techniques permit precise collection of intensity data at elevated temperatures, thus allowing a quantitative study of the temperature dependence of the structural parameters. However, our understanding of the process of thermal expansion is still poor, due to lack of precise data on the behavior of the vibrational properties of atoms. This is discussed by correlating concepts of crystal dynamics with modern theories of chemical bonding.

A neutron Fourier chopper for single crystal reflectivity measurements: some general design considerations

Neutron single-crystal analysis of complex protein structures requires the collection of intensity data on a large number of reflections. The use of time-of-flight analysis (in particular Fourier time-of-flight analysis employing phase detection) of diffraction data, offers a significant increase in the efficiency of the use of reactor neutrons. Such a method would facilitate the use of neutron diffraction in protein structure work. In this paper, we investigate the use of the Fourier chopper in single-crystal work. We examine the effect of various system parameters (frequency stability, flight path fluctuations, collimation, sample mosaic spread, inaccuracy in phase detection, and statistical counting errors) and determine general specifications for such an apparatus. None of these specifications appears to be beyond present day technology.

Automatic crystal alignment and intensity data collection with a computer controlled diffractometer

Automatic crystal alignment and intensity data collection with a computer controlled diffractometer

A low temperature system for automatic single crystal diffractometry.

An automated low temperature system, compatible with the PAILRED and other automatic diffractometers, has been developed and put into operation. Temperatures from ambient to −180°C can be maintained within ±0·2 degC for the hundreds of hours required for the collection of complete three-dimensional intensity data. Frost formation has been eliminated by surrounding the diffractometer with an enclosure within which the moisture content is 1 p.p.m. The precautions necessary to achieve this degree of dryness are discussed. An electropneumatic proportional control system maintains temperature by continuously adjusting both the flow rate of gaseous nitrogen through a pneumatic cryogenic valve and the boiling rate of liquid nitrogen. Temperature is sensed by a thermocouple close to the crystal and compared with a pre-selected temperature. Control action is proportional to the deviation signal. An all metal flexible transfer line conducts the nitrogen to the crystal. This line is continuously evacuated by small VacIon pumps producing a low temperature vacuum of 30 ntorr. Periodic transfer of liquid nitrogen from large commercially available reservoirs to the working Dewer is completely automatic and produces no significant upset of the established temperature. The method of temperature calibration by means of solid-liquid equilibration of organic fluids sealed in capillary tubes is discussed. Characteristic results for organic crystals are presented.

STUDIES OF INSULIN CRYSTALS AT LOW TEMPERATURES: EFFECTS ON MOSAIC CHARACTER AND RADIATION SENSITIVITY

The low-temperature X-ray diffraction studies of orthorhombic insulin citrate crystals reported here were initially undertaken because of the rapid deterioration at room temperature of certain insulin crystals containing heavy-metal cations. The effects of cooling on mosaic character and radiation sensitivity were studied. Two temperature ranges were employed: (a) below 150?C and (b) 00C to 13?C. In normal laboratory practice orthorhombic insulin citrate crystals are grown and stored at 1 i 1?0C. Immersion studies in heavy-atom reagents are also made at this temperature. All X-ray diffraction work is, however, carried out at room temperature ('-21 ?C). We have found that orthorhombic insulin citrate crystals may be cooled rapidly to below -1500 C without impairing the X-ray diffraction pattern. Rapid cooling does, however, enhance the mosaic character of these crystals. X-ray diffraction studies at 00C and 130C have provided evidence for marked reduction in radiation sensitivity in certain heavy-atom-containing crystals. General Background.-Although metal-free insulin crystals are somewhat more sensitive to radiation damage (nickel-filtered CuKa) at room temperature than at 00C, the radiation sensitivity at room temperature is not marked enough to prevent the collection of intensity data by counter techniques.' Furthermore, these crystals do not deteriorate on standing at room temperature for several weeks without irradiation. However, after immersion (1 i 1?C) in buffered solutions containing certain salts with heavy-metal cations (including uranyl) insulin crystals deteriorate rapidly at room temperature (sometimes within 1 day or less of exposure) after only the minimal radiation exposure (minutes) necessary to monitor the state of the crystal. The deterioration has been observed both in the presence and in the absence of significant changes in X-ray diffraction intensity distribution after immersion. It is not markedly accelerated by continuous X-ray irradiation. This deterioration was originally attributed to greatly enhanced radiation damage, as laboratory practice avoids keeping the crystals at room temperature prior to X-ray photography. Some apparent enhancement in radiation damage is also observed with a second group of metal-containing crystals which do not show the striking and rapid room-temperature deterioration reported above. Before the deterioration in the first class of crystals was recognized as largely of thermal origin, studies were made of both classes of metal-containing crystals into which radiation protectors had been introduced. These provided marginal evidence of protection. There was no evidence of protection when the crystals were studied under oxygen-free conditions. In order to collect X-ray data from the crystals which deteriorate rapidly at room temperature, it would have been necessary to build an apparatus to maintain

Full Circle Goniostat for Diffraction Intensity Data

A full circle goniostat is described for obtaining three-dimensional diffraction intensity data. This instrument permits a complete 360° motion in both φ and χ and a limited manual ω adjustment. Electronic angle setting and readout are provided, which facilitate automatic collection of intensity data.

Design for a three-circle X-ray goniometer

Using the scheme first described by Furnas and Harker, for the collection of three-dimensional intensity data from a single crystal in which the motion of the counter tube is restricted to a horizontal plane, a comparatively simple instrument is designed. Particular attention is given to the design of simple bearings which are free from backlash and wear, and which permit the recording of diffracted beams up to an angle of 2 theta of 165 deg . The instrument has provision for scanning and recording integrated intensities over an arc of 4 deg . Some details of performance are given. (auth)

Counter Adaptor and Furnace for Weissenberg Camera*

AbstractA rugged and versatile counter adaptor for a Weissenberg camera is described. It has performed well in two years of daily use which has included collection of intensity vs. temperature data with conventional cold-stream techniques.Advantage has recently been taken of the adaptor design to mount, directly on the Weissenberg base, a furnace device which blows hot air along the crystal mounting axis. Crystal temperature may be held constant or easily varied over the range up to about 700°C, with no obstruction of the X-ray beams and no readjustment of the furnace position, while the entire zero layer and close-in upper layers are explored.