bluuebunny/crossref_metadata_2025 huggingface dataset:
Airborne TEM surveying with a SQUID magnetometer sensor
Authors: Lee James B. , Dart David L. , Turner Robert J. , Downey Mark A. , Maddever Arthur , Panjkovic Goran , Foley Catherine P. , Leslie Keith E. , Binks Rex , Lewis Christopher , Murray Wayne
Published: October 2002

Traditionally airborne time-domain electromagnetic (AEM) survey systems use induction coils as the sensor (receiver). We have replaced the induction coil in a transient electromagnetic (TEM) system with a liquid-nitrogen cooled superconducting quantum interference device (SQUID) magnetometer sensor. Using this prototype system, we aimed to improve performance in detecting conductive mineralization, particularly where the conductive mineralization of interest is covered by a conductive regolith. We successfully demonstrated one- and three-component SQUID sensors in airborne TEM surveying, and achieved performance comparable to the induction-coil systems.

Implementation of the SQUID system required development of devices capable of operating in magnetically unshielded environments with low noise, high slew rate, and wide bandwidth. Operation of the SQUID sensor in the highly dynamic environment of a towed bird was also necessary, and this implies a high dynamic range and high level of noise associated with the motion in Earth's magnetic field. The high dynamic range of the SQUID response was handled by a combination of resetting the SQUID flux locked loop, reducing the bandwidth, and providing high-gain feedback in parallel with the flux locked loop. A digital stacking filter was used to eliminate low-frequency noise associated with sensor motion. Isolation of the sensor from motion at the TEM signal frequencies required development of a sophisticated suspension system.

The SQUID systems were tested over two known conductive targets, and their performance compared with the induction-coil TEM system. A comparative performance measure is developed to take the different sensitivities of the SQUID magnetometer and induction-coil receivers into account. This measure indicates that the SQUID system has superior performance for responses over earth structures with decay time constants greater than ∼6 ms when compared with the induction-coil signals. We also estimate the performance in comparison with integrated outputs of the induction-coil system and show that, at the demonstrated levels of SQUID performance, it is expected to have poorer performance by a factor of two or more. This disadvantage will be reduced for lower frequency, wider channel width TEM configurations or by improvements in the SQUID devices.
Multifocusing imaging over an irregular topography
Authors: Gurevich Boris , Keydar Shemer , Landa Evgeny
Published: October 2002

If seismic data are acquired over an irregular topography, standard elevation statics methods may be inaccurate because the assumption of vertical raypaths will no longer be valid. An effective solution to the problem of irregular topography can be found through the use of the multifocusing method, in which large supergathers of seismic traces are stacked, each of which can span many common midpoint (CMP) gathers. This can be done by extending the multifocusing moveout formula to explicitly account for nonzero elevations of the source and receiver, as well as their horizontal coordinates. Implementation of this formula into the multifocusing algorithm is straightforward because estimating the necessary raypath information (i.e., emergence angles) is an integral part of the algorithm. The extended multifocusing moveout correction can be applied directly to the data acquired in areas of irregular topography without the need for prior elevation static corrections. Synthetic tests on such data show that the proposed technique results in a better alignment of reflection events.
TO THE EDITOR
Authors: Kelly Sherwin F.
Published: October 2002

I wonder if as Editor of Geophysics you will give us your cooperation in a project being undertaken by a Committee of which I am a Chairman. This is the Committee on Geophysics Education of the Mineral Industry Education Division of the American Institute of Mining and Metallurgical Engineers. The Committee was organized a little over a year ago, for the purpose of conducting an enquiry into the present methods of reaching geophysics and the status occupied by such courses in university curricula.
Gravimetric and Magnetic Maps of the State of Missouri
Authors: Nettleton L. L.
Published: October 2002

The State of Missouri has recently published gravimetric and magnetic maps of the entire state.
On: “THE RELATIVE PLACE OF EMPIRICAL AND ANALYTICAL METHODS OF GEOPHYSICAL INTERPRETATION”
Authors: Macelwane James B.
Published: October 2002

The main contention of Mr. Weaver that mathematical and physical analysis of the problems involved should precede and accompany the field application of any geophysical method of prospecting rather than a purely empirical or trial‐and‐error approach is eminently sound, in my opinion. We may imagine where the electrical industry would be today if it had been forced to rely on trial‐and‐error methods of development rather than on the analysis of Kelvin, Maxwell, Heaviside, Steinmetz and their successors.
Reply by authors to discussion by L. P. Stephenson and R. D. Tooley
Authors: Viksne Andris , Berg Joseph W. , Cook Kenneth L.
Published: October 2002

In order that an understanding can be obtained of the analysis of the data presented in the subject paper by Viksne, Berg, and Cook, the following discusses the work in detail and compares the assumptions made in that work with the results of the analysis of the same data performed by Stephenson and Tooley in the preceding discussion. The topics that are considered are: (1) a discussion of the variables; (2) a review of the analysis performed by Viksne, Berg, and Cook, and (3) specific comments on the discussion by Stephenson and Tooley.
Reply by author to discussion by William C. Kellogg
Authors: Giret Raoul I.
Published: October 2002

Considering his large experience in magnetic surveying with the fluxgate magnetometer I have read with great attention the Letter to the Editor sent by Mr. William Kellogg about high sensitivity magnetic surveying. Most of his remarks confirm his experience. It is, however, a fact that high sensitivity magnetic surveying is quite different from conventional airborne surveying. CGG has now flown some 200,000 miles with the high sensitivity magnetometer and has just started to understand how different are the results obtained. In any method, a factor of ten gained in sensitivity changes completely the quality of the results and everyone has to get used to the new equipment before understanding all its advantages.
Comments on “The Use of Least Squares Method for the Interpretation of Data from Seismic Surveys” by A. E. Scheidegger and P. L. Willmore
Authors: Dix C. H.
Published: October 2002

Some aspects of this paper were of special interest to me mainly because they called attention to an unfamiliar method. The triangular resolution method I find especially interesting.
On: “THE EFFECT OF A CONDUCTING OVERBURDEN ON ELECTROMAGNETIC PROSPECTING MEASUREMENTS,” BY W. LOWRIE AND G. F. WEST (GEOPHYSICS, AUGUST, 1965, PP. 624–632)
Authors: Negi J. G.
Published: October 2002

The recent paper by Lowrie and West (1965) may prove to be a very valuable contribution in the study of the effect of overburden in geo-electromagnetics. The model experiments and their results look very impressive, but the interpretation of curves appears incomplete and incorrect in some respects. I have the following comments for the paper.
Reply by Author to Discussion by Dr. P. S. Naidu
Authors: Paul M. K.
Published: October 2002

I thank Dr. P. S. Naidu for his interest in my paper. My comments on his points are the following.
Reply by authors to discussion by Dr. George V. Keller.
Authors: Sanker Narayan P. V. , Ramanujachary K. R.
Published: October 2002

The authors are thankful to Dr. George Keller for pointing out some of the inherent inaccuracies in the method proposed by them and especially for drawing their attention to the work already done along the same lines. The authors were fully aware, at the time of presenting this short note, about the limitations pointed out by Dr. Keller in the use of Hummel’s principle, and that the proposed method is very approximate and also that the underlying assumptions cannot stand rigorous theoretical tests.
Reply by Author to Discussion by K. Biesheuvel
Authors: Paul M. K.
Published: October 2002

I have read Mr. Biesheuvel’s discussion on my paper with great interest. I thank him for his interest in my paper. I am not sure if Mr. Biesheuvel has been aware of another discussion on this paper and my reply to it (Geophysics, June 1968, p. 527‐528), which would have clarified my views on some of the criticisms made by him. However, my comments on his points are as below.
Reply by author to discussion by Robert L. Sax and Paul R. Lintz
Authors: Lacoss Richard T. , Kelly Edward J. , Toksöz M. Nafi
Published: October 2002

Messrs. Sax and Lintz have pointed out that our use of a “phase velocity vector” is misleading, because its use implies, to them, that the components of this vector are the apparent velocities of the wave along the coordinate directions. We did not make or intend this implication, of whose invalidity we were well aware, but we agree that our discussion could be confusing to some. It will be observed that all of our expressions which use this vector, equations (5), (6), (7), and (17), actually involved the quantities [Formula: see text] and [Formula: see text] which are, by our definitions (3), the components of the slowness vector. Hence our expressions for the plane‐wave moveouts are correct, if unconventional in form.
Reply by authors to discussion by M. Al‐Chalabi
Authors: McGrath P. H. , Hood P. J.
Published: October 2002

The success of any optimization method is primarily related to the smoothness and simplicity of the objective function in parameter space. Most optimization methods are successful when used with well‐behaved objective functions. As the complexity of the objective function in parameter space increases, much more sophisticated optimization strategies are required to assure convergence to an absolute (global) minimum.
On: “Instrumental Arrangement to Measure Gravity with Gradients,” by S. Thyssen-Bornemisza (GEOPHYSICS, August 1970, p. 713–715)
Authors: Thyssen-Bornemisza Stephen
Published: October 2002

The feasibility of measuring accurate relative gravity values with the gradiometer for absolute [Formula: see text] determination was not considered in the paper being discussed. Proceeding from formula (3b) or [Formula: see text], we take logarithms to get [Formula: see text]
Reply by author to G. L. Warren
Authors: Robinson John C.
Published: October 2002

Warren’s discussion is another attestation to the growing interest in and confusion about the effects of dispersion on seismic data. The discussion touches sporadically on several topics and is heavily laced with review material from previously published articles. However, there seem to be four specific notions upheld throughout which need to be addressed in response.
Reply to W. Anfiloff by the author
Authors: Fisher N. J.
Published: October 2002

The remarks of Anfiloff are clearly designed, not, as he claims in his opening paragraph, to narrow the gulf between the inversion and forward modeling approaches to interpretation, but instead to attempt to completely discredit the inversion philosophy, culminating in two somewhat emotional paragraphs. This threatens to be a greater hindrance to the ultimate aim of best possible interpretation than any shortcomings of current inversion methods. Modern inversion techniques are not “smart” algorithms for “hands‐off” automatic interpretation as Anfiloff suggests.
Reply to A. Roy and A. Apparao by author
Authors: Edwards L. S.
Published: October 2002

The calculation of absolute effective depth for any finite, realizable array can be based on the total array length L or on any other spacing factor desired. The burden of the discussion by Roy and Apparao is that the distance a between the active electrodes is the natural spacing factor for the 2‐pole array. I agree entirely with this, as evidenced by my statement that “the absolute effective depth is almost directly proportional to a”, and by my inclusion of [Formula: see text] coefficients in the first column of Table 2. I would consider the factors of this column to be the natural units for depth calculations for all arrays (except for the Schlumberger and gradient arrays, where L or the conventional L/2 is more suitable).
Reply by author to R. J. S. Brown and J. Korringa
Authors: Domenico S. N.
Published: October 2002

The author wishes to express his appreciation to Dr. Brown and Dr. Korringa for their interest in this paper and critical review of certain portions. Their discussion involves two aspects, namely (1) incorrect use of an approximate P‐wave velocity equation given by Geertsma (1961) as derived by Geertsma and Smit (1961) from Biot (1956), and (2) misidentification of the grain (solid) compressibility in derivation of an equation for the static frame compressibility.
Reply to discussion by P. H. Nelson and G. D. Van Voorhis by authors
Authors: Zonge K. L. , Wynn J. C.
Published: October 2002

The main objectives of “Recent Advances and Applications in Complex Resistivity Measurements” were to demonstrate the utility of making spectral measurements in standard field surveys and to show that rocks have characteristic signatures which do not conform to the constant phase model advocated by Nelson and Van Voorhis. We can understand the questions arising out of the relative inaccuracy statement.
Reply by R. L. Grasty, R. S. Foote, and K. L. Kosanke to W. C. Kellogg
Authors: Grasty R. L. , Foote R. S. , Kosanke K. L.
Published: October 2002

We agree almost entirely with the points made by Kellogg, but feel his confusion arises mainly through the concept of the “field of view” of a gamma‐ray detector. In fact a gamma‐ray detector does not have a fixed field of view in the optical sense, since it is theoretically possible for gamma rays to be detected from anywhere on the ground. It therefore remains to decide what is the most convenient and useful way to subdivide areas on the ground.
Reply by the author to J. Korringa and R. J. S. Brown
Authors: Lange James
Published: October 2002

An important feature of the dielectric properties of water in porous materials is that it does not behave like many other dielectric fluids of simpler microscopic structure. As a basis for evaluating the deviance of the dielectric properties of water, an experimental model is used in my paper. This experimental model is the volume fraction model and is determined from direct measurement. It involves no theoretical suppositions about the geometry of the composite dielectric material. This approach is taken to illustrate the unique physical properties of water rather than to adopt some theoretical model which depends upon some extraordinary insight into the “approximate” geometry of the composite dielectrics.
Reply by authors to G. C.‐C. Yao
Authors: Brown R. James , Anderson Neil L.
Published: October 2002

We wish to thank Mr. Yao for his vigilance in spotting the error in the Ricker wavelet frequency in our paper. Until about 1986, GMA associated a different frequency with a Ricker wavelet of breadth b. Nevertheless the breadth b, e.g., 30 ms, actually determines the Ricker wavelet in GMA’s software — only the frequency label has changed (G. R. Davidson and J. R. Townsley, pers. comm.).
Reply by the authors to M. K. Sengupta
Authors: Lange James N. , Almoghrabi Hamzah A.
Published: October 2002

The method presented in M. Sengupta’s patent provides a means of displaying both frequency and offset information necessary to evaluate the response of thin layers. Although it is developed to view P‐wave behavior, an adaptation of the technique might provide frequency‐domain information on mode‐converted S‐waves. Comparison of the P‐wave and mode‐converted S‐wave frequency‐domain behaviors yields important information on the lithology and pore‐fluid type of thin layers, as shown in Figure 11 of our paper.
Reply by the author to J. Roth
Authors: Mohan N. L.
Published: October 2002

We profusely thank Dr. J. Roth, Chief Geophysicist, Amax, Canada for having brought out a plausible suggestion regarding the inadequate acknowledgment of Nabighian’s outstanding contribution to the literature of geophysics.
On: “Approximating edges of source bodies from magnetic or gravity anomalies” by R. J. Blakely and R. W. Simpson (GEOPHYSICS, 51, 1494–1498, July 1986).
Authors: Pawlowski Robert S.
Published: October 2002

I would like to point out some minor errors which appear in this interesting and useful short note by Blakely and Simpson in which they describe an automated procedure for outlining the boundaries of gravity and magnetic source bodies. I stress that the errors are quite minor from the standpoint that they have no adverse impact on the textual content of the author’s paper. The errors must be recognized, however, if the algorithm is to be correctly implemented on a computer.
Reply by the authors to D. A. Chapin
Authors: Xia Jianghai , Sprowl Donald R. , Adkins‐Heljeson Dana
Published: October 2002

We thank Mr. Chapin for his comments on our paper. The fundamental impetus of our original research was the production of a topographically corrected map of the gravity of the State of Kansas; hence the inclusion of this product in the paper. Mr. Chapin correctly observes that the state maps do not highlight the utility of the method.
Reply by the authors to N. C. Steenland
Authors: Withers Robert , Eggers Dwight , Fox Thomas , Crebs Terry J.
Published: October 2002

The comments made by N. C. Steenland address issues of the aeromagnetic interpretation and gravity data inconsistencies. These comments will be addressed individually. The authors are very familiar with the method of aeromagnetic exploration having used it in various countries, geologic environments and applications. The technique is extremely powerful when used appropriately, and magnetics were not discounted summarily. In any paper on exploration we believe it is important that all results be discussed, and a worse disservice to the industry would have been to ignore aeromagnetics. Indeed, we would have expected criticism had we not reported on our findings about the applicability of magnetics on the Columbia River Basalts (CRB). It is our experience that working with other basalts of different ages and sources, such as the Snake River Basalt example discussed by the reviewer, may not be a guarantee of obtaining appropriate interpretations elsewhere.
Reply by the authors to B. Gurevich
Authors: Dai N. , Vafidis A. , Kanasewich E. R.
Published: October 2002

We thank B. Gurevich for interest shown in our paper. In exploration seismology, as noted by Dr. Gurevich, one can model effects in porous media by using the elastic wave equations with trial densities and velocities. Indeed we have, in the past, followed the approach discussed by Gurevich and modelled the earth with a single density and velocity structure in particular layers to simulate the combined effect of a fluid and a solid matrix on a number of occasions (Vafidis et al, 1992; Dai et al 1990) just to point out two papers. Our experience, particularly with higher frequency 3‐D data, is that the synthetic results never match field results and that more parameters are necessary to model partition of energy between different kinds of waves at the interfaces.
Reply by the authors to F. J. Esparza and E. Gómez‐Treviño
Authors: Jupp David L. B. , Vozoff Keeva
Published: October 2002

Despite the time that has passed since the original short discussion, I think some useful points can be made regarding the note by Esparza and Gómez‐Treviño. First, the authors are quite correct to point out that (3) of their note is not a rotation invariant definition of phase as was claimed in the original discussion. This slip most likely carried into later texts unchallenged. The fact is, however, that (3) is rotation invariant for a 2‐D earth. It was in this context that the change was made to the definition in Vozoff (1971).
Orbital vibrator seismic source for simultaneous P‐ and S‐wave crosswell acquisition
Authors: Daley Thomas M. , Cox Dale
Published: October 2002

A recently developed borehole seismic source, the orbital vibrator, was successfully deployed in a crosswell survey in a fractured basalt aquifer. This seismic source uses a rotating eccentric mass to generate seismic energy. Source sweeps with clockwise and counter‐clockwise rotations are recorded at each source location. Because this source generates circularly polarized waves, unique processing algorithms are used to decompose the recordings into two equivalent linearly oscillating, orthogonally oriented seismic sources. The orbital vibrator therefore generates P‐ and S‐waves simultaneously for all azimuths. A coordinate rotation based on P‐wave particle motion is used to align the source components from various depths. In a field experiment, both P‐ and S‐wave arrivals were recorded using fluid‐coupled hydrophone sensors. The processed field data show clear separation of P‐ and S‐wave arrivals for in‐line and crossline source components, respectively. A tensor convolutional description of the decomposition process allows for extension to multicomponent sensors.
Modeling and imaging with the scalar generalized‐screen algorithms in isotropic media
Authors: Le Rousseau Jéro⁁me H. , de Hoop Maarten V.
Published: October 2002

The phase‐screen and the split‐step Fourier methods, which allow modeling and migration in laterally heterogeneous media, are generalized here so as to increase their accuracies for media with large and rapid lateral variations. The medium is defined in terms of a background medium and a perturbation. Such a contrast formulation induces a series expansion of the vertical slowness in which we recognize the first term as the split‐step Fourier approximation and the addition of higher‐order terms of the expansion increases the accuracy. Employing this expansion in the one‐way scalar propagator yields the scalar one‐way generalized‐screen propagator. We also introduce a generalized‐screen representation of the reflection operator. The interaction between the upgoing and downgoing fields is taken into account by a Bremmer series. These results are then cast into numerical algorithms. We analyze the accuracy of the generalized‐screen method in complex structures using synthetic models that exhibit significant multipathing: the IFP 2‐D Marmousi model and the SEG‐EAGE 3‐D salt model. As compared with the split‐step Fourier method, in the presence of lateral medium variations, the generalized‐screen methods exhibit an increased accuracy at wider angles of propagation and scattering. As a result, in the process of migration, we can choose a member of the family of our generalized‐screen algorithms in accordance with the complexity of the medium (velocity model).
Using homotopy to invert geophysical data
Authors: Jegen Marion D. , Everett Mark E. , Schultz Adam
Published: October 2002

Homotopy is a powerful tool for solving nonlinear equations. It is used here to solve small‐dimensional geophysical inverse problems by locating the solutions of the governing normal equations. An Euler‐Newton numerical continuation scheme is used to map trajectories in model space that start from a prescribed solution to a trivial set of equations and terminate at a solution to the inverse problem. The trajectories often map out a continuum of equivalent solutions that are caused by model equivalences or overparameterization. This allows exploration of the solution space topology. The homotopy method, in this application, is relatively insensitive to the choice of starting model. Several examples based on synthetic controlled‐source electromagnetic (CSEM) responses are shown to illustrate the method. An inversion of actual CSEM data from the Canadian Shield is also provided.
Minimizing field operations in shallow 3‐D seismic reflection surveying
Authors: Spitzer Roman , Green Alan G. , Nitsche Frank O.
Published: October 2002

By appropriately decimating a comprehensive shallow 3‐D seismic reflection data set recorded across unconsolidated sediments in northern Switzerland, we have investigated the potential and limitations of four different source‐receiver acquisition patterns. For the original survey, more than 12 000 shots and 18 000 receivers deployed on a [Formula: see text] grid resulted in common midpoint (CMP) data with an average fold of ∼40 across a [Formula: see text] area. A principal goal of our investigation was to determine an acquisition strategy capable of producing reliable subsurface images in a more efficient and cost‐effective manner. Field efforts for the four tested acquisition strategies were approximately 50%, 50%, 25%, and 20% of the original effort. All four data subsets were subjected to a common processing sequence. Static corrections, top‐mute functions, and stacking velocities were estimated individually for each subset. Because shallow reflections were difficult to discern on shot and CMP gathers generated with the lowest density acquisition pattern (20% field effort) such that dependable top‐mute functions could not be estimated, data resulting from this acquisition pattern were not processed to completion. Of the three fully processed data subsets, two (50% field effort and 25% field effort) yielded 3‐D migrated images comparable to that derived from the entire data set, whereas the third (50% field effort) resulted in good‐quality images only in the shallow subsurface because of a lack of far‐offset data. On the basis of these results, we concluded that all geological objectives associated with our particular study site, which included mapping complex lithological units and their intervening shallow dipping boundaries, would have been achieved by conducting a 3‐D seismic reflection survey that was 75% less expensive than the original one.
Modeling non‐Gaussian reflectivities: Generalizing Wiener‐Levinson deconvolution
Authors: Tenorio Luis
Published: October 2002

Non‐Gaussian modeling is used to generalize Wiener—Levinson (WL) deconvolution and to obtain a procedure that is more robust to nonstationarities in the reflectivity and to correlated noise. This generalization can lead to up to a 60% reduction in the dynamic range of the residual wavelet’s amplitude response and in the rms error of phase estimates. In addition, it reduces to WL deconvolution when the reflectivity is Gaussian or when noise masks the nonstationary features of the reflectivity.
Robust sensor fault diagnosis and validation in HVAC systems
Authors: Wang Shengwei , Wang Jin-Bo
Published: October 2002

A robust fault diagnosis and validation strategy for temperature sensors and ‘ow meters in central chilling plant is developed, which is based on the first law of thermodynamics. The strategy evaluates soft sensor faults (biases) by examining and minimizing the sum of the squares of concerned mass or steady state energy balance residuals represented by the corrected measurement over a period. It considers systematically all the concerned energy balances and obtains the best estimates of the sensor biases by minimizing the sum of the mean squares of normalized residuals of all energy balances involved. The genetic algorithm technique is employed to determine the global minimal solution to the multimodal objective function, which can be difficult to achieve by traditional gradient-directed search methods. Performance of an advanced robust fault detection, diagnosis and evaluation (FDD&E) scheme is compared with that of a sequential scheme, which was reported earlier, in simulation tests. The robust scheme is superior to the sequential scheme in robustness to abrupt sensor faults, such as biases, etc. The robust scheme is applied to a central chilling plant in an existing commercial building, providing satisfied bias estimates. As a basic method, the sensor FDD&E strategy is of practical value in heating, ventilation and air-conditioning (HVAC) systems as well as in systems where the measurements of liquid ‘ow variables are essential to control and performance monitoring.
Multiple model nonlinear control of synchronous generators
Authors: Brown M. D. , Flynn D. , Irwin G. W.
Published: October 2002

Research has shown that conventional adaptive control and more sophisticated nonlinear approaches can suffer from a lack of robustness and transparency. In this paper, a multiple model technique is proposed that effectively incorporates established linear control methods within an inherently nonlinear framework. The resulting local model network (LMN) was found to describe the nonlinear dynamics of a laboratory turbogenerator excitation loop over its useful operating range. A simple nonlinear generalized minimum variance (GMV) controller was then designed for this system and compared with an adaptive GMV controller. The excellent control performance and transparent nature of the LMN illustrates the potential for this technique for a range of nonlinear control problems.
Part load efficiency of air-cooled multiple-chiller plants
Authors: Chan K T , Yu F W
Published: October 2002

This paper reports an analysis of the energy efficiency of air-cooled chiller plants in buildings and opportunity of improved part load efficiency. Load-frequency profile, weather-load profile and thermal performance lines obtained by simulation of typical office and hotel buildings in a subtropical climate are examined to address the methods of determining the plant size, identifying the loading characteristics, optimizing the combination of multiple-chillers and evaluating the energy saving alternatives in design or retrofit. It is shown that the percentage design load for office is best related to external temperature; for hotels the product of external temperature and humidity is more appropriate as a climatic index. The results indicate that for a particular value of percentage design load, the likely outdoor temperature can be determined statistically, and the consumption can be determined from a set of chiller efficiency curves as a function of chiller part load ratio and entering condenser air temperature. The opportunity for improving the operating efficiency of air-cooled multiple-chiller plants by lowering the condensing temperature at lower outdoor temperatures is discussed.
The Nottingham energy, health and housing study: reducing relative humidity, dust mites and asthma
Authors: Pretlove S E C , Critchley R , Howard R , Oreszczyn T
Published: October 2002

This paper describes the Nottingham energy, health and housing study, a project where seven Nottingham City Council households subject to either fuel poverty or heat poverty have been refurbished to improve the internal environmental conditions and therefore the health of the occupants. The main aim was to provide improvements in ventilation, insulation, draughtproofing and heating control in the dwellings. An intervention study was carried out in the seven dwellings where temperature, relative humidity, health, dust mite numbers and ventilation were measured before the introduction of a range of heating, ventilation and insulation improvements. These were then monitored again a year later. The results of the study indicate that with a limited budget, significant improvements have been realized in the comfort levels of the occupants and in their health. Modelling of the environmental conditions and energy consumption in each dwelling has been carried out using the steady-state Condensation Targeter II model. Comparisons between the model predictions and the measured data show that Condensation Targeter II can be used as an effective tool for selecting the most appropriate design modifications for an individual dwelling and can assess the impact that these modifications will have on the energy efficiency of the dwelling and the health of the occupants.
Scores on a yes-no vocabulary test: correction for guessing and response style
Authors: Huibregtse Ineke , Admiraal Wilfried , Meara Paul
Published: October 2002

The use of yes-no tests seems to be a promising method for measuring the size of receptive vocabulary knowledge of learners of a foreign language. Items in a yes-no test each consist of either a word or a pseudoword. Participants are asked to indicate whether or not they know the meaning of these words. This article attempts to tackle the problem of determining a meaningful score for this type of test. Such a score should contain correction for guessing as well as for participants’ response style. Three possible methods are discussed, but none of these measures appear to apply this type of correction. Signal Detection Theory is applied and a new, more accurate index is suggested. Based on theoretical as well as empirical considerations, recommendations are made about the choice for the index to be used in a yes-no vocabulary test.
Self esteem of children with specific speech and language difficulties
Authors: Lindsay Geoff , Dockrell Julie , Letchford Becky , Mackie Clare
Published: October 2002

This study examines the self esteem of children with specific speech and language impairment. A sample of 69 children was first identified in Year 3. The present study focuses on their self esteem as measured by the Self Perception Profile for Children when the children were in Years 6 and 7. Data are presented for the children’s self perception and for teachers’ perceptions on the same dimensions. The children with SSLD had lower ratings of scholastic competence than typically developing peers, and teachers in Year 6, but not Year 7, rated the children significantly lower on these two dimensions than the children rated themselves. Comparisons between measures at Year 3, 6 and 7 revealed substantial continuities for both children’s and teachers’ perceptions between Year 6 and 7, and for teachers from Year 3 to Years 6 and 7. The results are interpreted with reference to theories of self esteem and the educational needs of children with SSLD.
In vitro hydrodynamics of the Embol-X cannula
Authors: Gerdes Anja , Hanke Thorsten , Sievers Hans-H
Published: October 2002

Background: Prevention of intraoperative plaque dislodgement in patients with atherosclerotic ascending aorta by development of innovative aortic cannula designs gains growing interest in cardiac surgery. To increase knowledge about the hydrodynamics of the innovative Embol-X™ cannula, which includes an intra-aortic filter device targeting at atheromatous emboli capture, was the aim of the present study.

Methods: Pressure gradients and back pressures of the Embol-X™ cannula were measured at varying flow rates in a mock circulation and compared with two commonly used single-stream cannulae.

Results: At a flow rate of 5.5 l/min, pressure gradients across the Argyle™ and the RMI cannulae were 48% and 62% and back pressures 25% and 47% lower than the corresponding values across the Embol-X™ cannula.

Conclusions: The novel concept of integrating a filter device may provide clinical advantages concerning neurologic outcome. Further in vivo studies seem to be desirable to obtain more information concerning the clinical effects of the Embol-X™ cannula hydrodynamics.
An in vitro method for comparing biocompatibility of materials for extracorporeal circulation
Authors: Peek Giles J , Scott Richard , Killer Hilliary M , Firmin Richard K
Published: October 2002

We measured the response of fresh heparinized human blood to recirculation through circuits made of LVA (Portex Industries, Hythe, Kent, UK), SRT (Rehau UK, Langley, Slough, UK) and Tygon® S-65-HL (Norton Performance Plastics, Corby, Northants, UK), as control.

Circuit construction: 1/2 in. tubing, heat exchanger (Dideco D-720P), Stockert roller pump, just underoccluded, Cincinnati Sub Zero heater, circuit volume of 500 ml. Flow 3.45 l/min, 37°C.

Samples: at 10 min, 1, 2, 4 and 6 h. n= 5 in each group; 2/5 SRT experiments were stopped at 45 and 60 min due to overpressurization.

Results: Baseline activated clotting time (ACT) of 300 s, increasing in all groups as fibrinogen fell to zero with SRT and LVA. Minimum fibrinogen was 1 g/l for Tygon. Absolute thrombocytopenia occurred (SRT and LVA 60 min and Tygon 240 min). International normalized ratio (INR) in both the SRT and LVA circuits increased, but mean increase for Tygon (0.56) was smaller than the other two materials. Plasma free haemoglobin increased in all three materials; the increase was greater in the LVA circuits compared to the control. C5b9 levels increased equally in all groups. Lactoferrin levels rose equally in all groups to a maximum at 150 min. The neutrophil counts fell, mirroring the lactoferrin. The total white cell counts also fell in all groups; in the LVA circuits, the fall was significantly lower than in the control. Rapid disappearance of platelets and fibrinogen from the blood in the SRT and LVA circuits excludes them both from extracorporeal use. Paradoxically, SRT caused the least complement activation of the three materials. This method can be used to compare biocompatibility.
Heparin-bonded circuits without a cardiotomy: a description of a minimally invasive technique of cardiopulmonary bypass
Authors: Lilly Kevin J , O’Gara Paul J , Treanor Patrick R , Crowley Richard , Reardon Deborah L , Shapira Oz M , Khuri Shukri F , Aldea Gabriel S , Shemin Richard J
Published: October 2002

The deleterious effects of cardiotomy suction have been well recognized and well documented for some time. The use of cardiotomy suction results in the exposure of blood to the defoaming sock, aspiration of stagnant pericardial blood into the systemic circulation, and the entrainment of both fatty and gaseous microemboli. The purpose of this paper is to describe a technique using heparin-bonded cardiopulmonary circuits (HBCs) without the use of a cardiotomy reservoir or cardiotomy suction. Our group has previously demonstrated improved clinical outcomes using HBCs and a low-dose anti-coagulation protocol. It is our goal to further improve clinical outcomes and further attenuate the deleterious effects of cardiopulmonary bypass by eliminating the potential complications attributed to the use of cardiotomy suction.
Intraoperative treatment strategy to reduce the incidence of postcardiopulmonary bypass atrial fibrillation
Authors: Olivencia-Yurvati A H , Wallace W E , Wallace N , Dimitrijevich D , Knust J K , Haas L , Raven P B
Published: October 2002

Purpose: Postcardiopulmonary bypass atrial fibrillation remains a constant complication associated with coronary revascularization, the incidence of which occurs from 20% to 35%. Previous studies have addressed this problem in the postoperative setting utilizing pharmacological agents, but the results have been variable. The purpose of this study was to evaluate a novel intraoperative strategy to reduce the incidence of postcardiopulmonary bypass atrial fibrillation. We theorized that leukocyte depletion by filtration with the addition of aprotinin would reduce the systemic inflammatory effects of bypass and reduce the incidence of atrial fibrillation.

Methods: One hundred and twenty-two patients participated in this randomized study. Only isolated primary coronary revascularization procedures on cardiopulmonary bypass were included. The control group (n= 55) received standard moderate hypothermic blood cardioplegia cardiopulmonary bypass. The treatment group (n= 65) received similar cardiopulmonary bypass with the addition of strategic leukocyte depletion with Pall Biomedical Products (East Hills, NY) leukodepletion filters and full-dose aprotinin.

Results: The intra-operative addition of leukocyte depletion by filtration with aprotinin reduced the incidence of postcardiopulmonary bypass atrial fibrillation by 72%. The incidence of atrial fibrillation in the control group was 27% (15 of 55). In contrast, the occurrence of atrial fibrillation in the treated group was only 7.6% (5 of 65) (p< 0.025).

Conclusions: This novel intraoperative treatment strategy of both mechanical (leukocyte filtration) and pharmacological (aprotinin) intervention appears to markedly reduce the incidence of postcardiopulmonary bypass atrial fibrillation. To our knowledge, this is the first study to combine these two treatment strategies. A previous study has noted a decline in atrial fibrillation with aprotinin in the animal model, but not to the extent observed in our study. The beneficial effects of the reduction of atrial fibrillation include reduced risk of emboli formation and the incidence of ischemia in the heart, lung and brain. In addition, a decrease in length of hospital stay, recovery time and overall cost occurred.
The role of leukodepletion in limiting ischemia/reperfusion damage in the heart, lung and lower extremity
Authors: Allen Bradley S
Published: October 2002

This article describes the experimental infrastructure and subsequent clinical application of a comprehensive reper-fusion strategy to limit the injury following ischemia, resulting in an improvement in post operative organ function. In particular, it examines the role of luekodepletion in minimizing damage and improving functional outcome in the heart, lung and lower extremity. During cardiothoracic procedures, various organs can be subjected to temporary ischemia, particularly the heart (cardioplegic arrest), lung (transplant), and lower extremity (femoral canulation, IABP). The background of ischemia/reperfusion injury is discussed as it applies to each of these 3 organs, as well as findings that ischemia followed by reperfusion results in a similar injury in each organ. Data are then presented to demonstrate that a comprehensive reperfusion strategy, utilizing a modified substrate-enriched blood reperfusatedeliveredat a low pressure can limit this injury, and that adding white blood cell filtration significantly improves the efficacy of this approach. These principles have now been used in a series of patients undergoing various surgical procedures with excellent results. Applicationof theseconcepts may significantlyimprove theoutcome in patients undergoing procedures which subject these organs to temporary ischemia.
The Action Research Arm Test: is it necessary for patients being tested to sit at a standardized table?
Authors: Hsueh I-Ping , Lee Ming-Mei , Hsieh Ching-Lin
Published: October 2002

Objective: To validate results obtained from using the Action Research Arm Test (ARAT) at tables of a common height for persons who have experienced a stroke.

Design: Each subject was tested three times with the ARAT while sitting at three different tables: a table specially designed for the test and two generally available tables similar in height to the standard table. The patients were randomly and equally assigned to three different raters and to three different tables in accordance with a counterbalanced design. All evaluations were completed within a two-day period.

Subjects: Sixty-one patients who had had only one stroke (mean age 63.3 years; median time since stroke onset 81 days; mean ARAT score administered at the standard table 33.8) participated in this study.

Results: The intraclass correlation coef”cient (ICC) for the total scores obtained using the ARAT at the different tables was 0.99, indicating very high agreement. The ICCs were also very high in each of the subscales.

Conclusion: The results of this study support the use of the ARAT at ordinary tables roughly similar in height to that specially designed for use with the ARAT.
Co-morbidity adjustment for functional outcomes in community-dwelling older adults
Authors: Rigler Sally K , Studenski Stephanie , Wallace Dennis , Reker Dean M , Duncan Pamela W
Published: October 2002

Objective: To characterize relationships between self-reported co-morbidity and functional outcomes in community-dwelling older adults, and to assess whether the impact of co-morbidity persists even after adjustment for baseline functional status.

Design: Prospective observational study. We examined associations between self-reported co-morbidity at baseline and functional outcomes at one year, with and without adjustment for baseline functional status.

Setting: Outpatient clinics at a managed care and a Veterans Affairs site.

Subjects: Four hundred and ”fty-seven community-dwelling older adults representing a broad spectrum of overall health status.

Main outcome measures: (a) New basic ADL (activities of daily living) problem during follow-up; (b) 10-point decline in the physical function index of the MOS-36 (MOS-PFI).

Results: Co-morbidity was associated with adverse functional outcomes in bivariable analyses. After adjustment for age and baseline functional status, an accumulated co-morbidity score provided additional explanatory power for predicting new ADL problems; odds ratios were 2.30 (1.09, 5.09) and 2.96 (1.48, 6.25) for 2 and 33 affected co-morbidity domains, respectively. The impact of baseline status was also important; odds ratios for new ADL problems were 4.77 (2.68, 8.81) when at least one instrumental activity of daily living (IADL) problem was present at baseline, and 15.6 (8.05, 31.3) when at least one basic ADL problem was present at baseline.

Conclusions: Accumulated self-reported co-morbidity has signi”cant negative effects on function at one year; these effects are attenuated but not eliminated by adjustment for baseline status. Co-morbidity adjustment is probably an important design element in clinical research focused on functional outcomes in older adults.
Difficulties associated with wrist disorders – a qualitative study
Authors: Bialocerkowski Andrea E
Published: October 2002

Objective: To explore the range of functional dif”culties and compensatory mechanisms reported by individuals with a wrist disorder, to provide a basis for development of a patient-focused outcome instrument.

Design: Descriptive study using a qualitative, interview-based framework.

Setting/subjects: A volunteer sample of individuals, who were diagnosed with a unilateral, localized wrist disorder, were recruited from a wide range of health care settings situated in different socio-economic and geographic areas of Adelaide, Australia. Recruitment continued until theoretical saturation of the data occurred.

Interventions: Semi-structured, audiotaped interviews were conducted with each individual to elicit information concerning ‘how your wrist disorder has affected your ability to perform daily activities’.

Main outcome measures: Trends regarding reporting of dif”cult activities and compensatory mechanisms used.

Results: Forty-two individuals were interviewed. This was the point where theoretical saturation of research information had been reached. A few individuals reported dif”culty with functional tasks prior to wrist injury. Following diagnosis, a wide range of dif”culties, which included heavy, gross and ”ne motor activities, was reported. Compensatory mechanisms were used by all individuals, with requesting someone else to do the task, using the other hand, and using other parts of the body to lift or grasp being the most common.

Conclusions: Current wrist outcome instruments do not contain the full range of dif”cult activities that were elicited from our sample, which casts doubt on these instruments’ ability to fully measure change in capacity. Our results should provide the basis for the development of a relevant, sensitive, patient-focused outcome instrument.