bluuebunny/crossref_metadata_2025 huggingface dataset:
A SLOPING BOUNDARY CONDITION FOR EFFICIENT PE CALCULATIONS IN RANGE–DEPENDENT ACOUSTIC MEDIA
Authors: BROOKE GARY H. , THOMSON DAVID J. , WORT PHILIP M.
Published: November 2004

The traditional one-way parabolic equation (PE) formulation for range-dependent layered acoustic media is modified to include effects associated with the boundary conditions along a sloping interface. Essentially, the boundary condition for continuity of the normal displacement along a sloping interface is cast in an approximate form which does not depend on range but does contain terms up to second order in the derivatives with respect to depth. The new sloping-boundary condition is then applied along an "equivalent" horizontal interface within each range-independent step of the PE. Numerical results obtained for standard test cases indicate that the sloping-boundary condition, incorporated into a one-way PE, maintains the efficiency yet improves the accuracy of forward predictions.
A COUPLED–MODE FORMULATION FOR THE SOLUTION OF THE HELMHOLTZ EQUATION IN WATER IN THE PRESENCE OF A CONICAL SEA-MOUNT
Authors: TAROUDAKIS MICHAEL I.
Published: November 2004

The problem of determining the acoustic field in the sea due to a point harmonic source around a penetrable sea-mount of conical shape is handled in terms of normal-mode theory. The sea-mount is divided in cylindrical segments-rings, in each of which, a series expansion of the acoustic pressure in terms of normal modes and cosine functions is considered. A similar series expansion is considered for the external field and the coefficients of the various expansions are calculated by solving linear systems of equations resulting from the application of the continuity conditions of the pressure field and normal component of the particle velocity at the artificial interfaces of the cylindrical segments-rings. Since Hankel functions of high order are involved in the expansions, numerical problems arise in the numerical implementation of the scheme in cases of low convergence rate. Numerical results are presented for some simple cases of very low frequency propagation around a cylindrical mount.
Polarized expression of human P2Y receptors in epithelial cells from kidney, lung, and colon
Authors: Wolff Samuel C. , Qi Ai-Dong , Harden T. Kendall , Nicholas Robert A.
Published: November 2004

Eight human G protein-coupled P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14) that respond to extracellular nucleotides have been molecularly identified and characterized. P2Y receptors are widely expressed in epithelial cells and play an important role in regulating epithelial cell function. Functional studies assessing the capacity of various nucleotides to promote increases in short-circuit current ( Isc) or Ca2+ mobilization have suggested that some subtypes of P2Y receptors are polarized with respect to their functional activity, although these results often have been contradictory. To investigate the polarized expression of the family of P2Y receptors, we determined the localization of the entire P2Y family after expression in Madin-Darby canine kidney (MDCK) type II cells. Confocal microscopy of polarized monolayers revealed that P2Y1, P2Y11, P2Y12, and P2Y14 receptors reside at the basolateral membrane, P2Y2, P2Y4, and P2Y6 receptors are expressed at the apical membrane, and the P2Y13 receptor is unsorted. Biotinylation studies and Isc measurements in response to the appropriate agonists were consistent with the polarized expression observed in confocal microscopy. Expression of the Gq-coupled P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, and P2Y11) in lung and colonic epithelial cells (16HBE14o− and Caco-2 cells, respectively) revealed a targeting profile nearly identical to that observed in MDCK cells, suggesting that polarized targeting of these P2Y receptor subtypes is not a function of the type of epithelial cell in which they are expressed. These experiments highlight the highly polarized expression of P2Y receptors in epithelial cells.
Role of angiotensin in body fluid homeostasis of mice: effect of losartan on water and NaCl intakes
Authors: Crews Emily C. , Rowland Neil E.
Published: November 2004

It is known that mice injected peripherally with ANG II do not show a drinking response but that cFos immunoreactivity (ir) is induced in brain regions similar to those in rats. We now show in Crl:CD1(ICR) mice that peripheral injection of the ANG II type 1 receptor antagonist losartan was sufficient to prevent this induction of Fos-ir in the subfornical organ (SFO). Injection of ANG II into the lateral cerebral ventricle produced a robust water intake in mice and induced Fos-ir in SFO, as well as in median preoptic (MnPO) and paraventricular (PVN) nuclei. Peripheral injection of losartan blocked this drinking response and prevented the induction of Fos-ir in each of these brain regions. Hypovolemia produced by polyethylene glycol (PEG) produced a robust water intake but no evidence of sodium appetite, and it induced Fos-ir in SFO, MnPO, and PVN. Peripheral injection of losartan did not affect this drinking response. Fos-ir induced by PEG in SFO and MnPO was reduced by treatment with losartan, while that induced in the PVN was further increased by losartan. Sodium depletion with furosemide and low-sodium diet produced a strong sodium appetite and induced Fos-ir in SFO and MnPO. Treatment with losartan completely blocked the sodium appetite, as well as the induction of Fos-ir in these brain regions. These data indicate that endogenous production of ANG II and action at forebrain receptors is critically involved in depletion-related sodium appetite in mice. The absence of an effect of losartan on PEG-induced drinking suggests the critical involvement of other factor(s) such as arterial or venous baroreceptor input, and we discuss how this factor could also explain why peripheral ANG II is not dipsogenic in mice.
Estrogen and Inflammation Increase the Excitability of Rat Temporomandibular Joint Afferent Neurons
Authors: Flake Natasha M. , Bonebreak David B. , Gold Michael S.
Published: November 2004

Several painful conditions, including temporomandibular disorders (TMD), are more prevalent and more severe in women than in men. Although the physiological basis for this sex difference remains to be determined, it is likely that estrogen is an underlying factor. The present study was performed to test the hypotheses that estrogen increases the excitability of rat temporomandibular joint (TMJ) afferents and exacerbates the inflammation-induced sensitization of these sensory neurons. Retrogradely labeled TMJ neurons from ovariectomized rats and ovariectomized rats receiving chronic estrogen replacement were studied using whole cell patch-clamp techniques three days after injecting the TMJ with either saline or Complete Freund's Adjuvant to induce inflammation. Excitability was assessed with depolarizing current injection to determine action potential threshold, rheobase, and the response to suprathreshold stimuli. Spontaneous activity was also assessed. Both inflammation and estrogen increased the excitability of TMJ neurons as reflected by decreases in action potential threshold and rheobase and increases in the incidence of spontaneous activity. The effects were additive with neurons from rats receiving both estrogen and inflammation being the most excitable. The increases in excitability were associated with changes in passive properties and action potential waveform, suggesting that estrogen and inflammation affect the expression and/or properties of ion channels in TMJ neurons. Importantly, the influence of estrogen on both baseline and inflammation-induced changes in TMJ neuronal excitability may help explain the profound sex difference observed in TMD as well as suggest a novel target for the treatment of this pain condition.
Activity of Pyramidal Tract Neurons in the Cat During Postural Corrections
Authors: Beloozerova I. N. , Sirota M. G. , Orlovsky G. N. , Deliagina T. G.
Published: November 2004

The dorsal side-up body orientation in quadrupeds is maintained by a postural control system. We investigated participation of the motor cortex in this system by recording activity of pyramidal tract neurons (PTNs) from limb representations of the motor cortex during postural corrections. The cat was standing on the platform periodically tilting in the frontal plane, and maintained equilibrium at different body configurations: with the head directed forward (symmetrically alternating loading of the left and right fore limbs), or with the head voluntary turned to the right or to the left (asymmetrical loading). We found that postural corrective responses to tilts included an increase of the contact forces and activity of limb extensors on the side moving down, and their decrease on the opposite side. The activity of PTNs was strongly modulated in relation to the tilt cycle. Phases of activity of individual PTNs were distributed over the cycle. Thus the cortical output mediated by PTNs appeared closely related to a highly automatic motor activity, the maintenance of the body posture. An asymmetrical loading of limbs, caused by head turns, resulted in the corresponding changes of motor responses to tilts. These voluntary postural modifications were also well reflected in the PTNs' activity. The activity of a part of PTNs correlated well with contact forces, in some others with the limb muscle activity; in still others no correlation with these variables was observed. This heterogeneity of the PTNs population suggests a different functional role of individual PTNs.
Intersegmental Coordination of Walking Movements in Stick Insects
Authors: Ludwar Björn Ch. , Göritz Marie L. , Schmidt Joachim
Published: November 2004

Locomotion requires the coordination of movements across body segments, which in walking animals is expressed as gaits. We studied the underlying neural mechanisms of this coordination in a semi-intact walking preparation of the stick insect Carausius morosus. During walking of a single front leg on a treadmill, leg motoneuron (MN) activity tonically increased and became rhythmically modulated in the ipsilateral deafferented and deefferented mesothoracic (middle leg) ganglion. The pattern of modulation was correlated with the front leg cycle and specific for a given MN pool, although it was not consistent with functional leg movements for all MN pools. In an isolated preparation of a pair of ganglia, where one ganglion was made rhythmically active by application of pilocarpine, we found no evidence for coupling between segmental central pattern generators (CPGs) that could account for the modulation of MN activity observed in the semi-intact walking preparation. However, a third preparation provided evidence that signals from the front leg's femoral chordotonal organ (fCO) influenced activity of ipsilateral MNs in the adjacent mesothoracic ganglion. These intersegmental signals could be partially responsible for the observed MN activity modulation during front leg walking. While afferent signals from a single walking front leg modulate the activity of MNs in the adjacent segment, additional afferent signals, local or from contralateral or posterior legs, might be necessary to produce the functional motor pattern observed in freely walking animals.
Hypercapnic Exposure in Congenital Central Hypoventilation Syndrome Reveals CNS Respiratory Control Mechanisms
Authors: Harper R. M. , Macey P. M. , Woo M. A. , Macey K. E. , Keens T. G. , Gozal D. , Alger J. R.
Published: November 2004

Congenital central hypoventilation syndrome (CCHS) patients show impaired ventilatory responses and loss of breathlessness to hypercapnia, yet arouse from sleep to high CO2, suggesting intact chemoreceptor afferents. The syndrome provides a means to differentiate brain areas controlling aspects of breathing. We used functional magnetic resonance imaging to determine brain structures responding to inspired 5% CO2-95% O2in 14 CCHS patients and 14 controls. Global signal changes induced by the challenge were removed on a voxel-by-voxel basis. A priori-defined volume-of-interest time trends (assessed with repeated measures ANOVA) and cluster analysis based on modeling each subject to a step function (individual model parameter estimates evaluated with t-test, corrected for multiple comparisons) revealed three large response clusters to hypercapnia distinguishing the two groups, extending from the 1) posterior thalamus through the medial midbrain to the dorsolateral pons, 2) right caudate nucleus, ventrolaterally through the putamen and ventral insula to the mid-hippocampus, and 3) deep cerebellar nuclei to the dorsolateral cerebellar cortex bilaterally. Smaller clusters and defined areas of group signal differences in the midline dorsal medulla, amygdala bilaterally, right dorsal-posterior temporal cortex, and left anterior insula also emerged. In most sites, early transient or sustained responses developed in controls, with little, or inverse change in CCHS subjects. Limbic and medullary structures regulating responses to hypercapnia differed from those previously shown to mediate loaded breathing ventilatory response processing. The findings show the significant roles of cerebellar and basal ganglia sites in responding to hypercapnia and the thalamic and midbrain participation in breathing control.
Thermal Transport in Graphitic Carbon Foams
Authors: Alam M. K. , Druma A. M. , Druma C.
Published: November 2004

A number of carbon foam products are being developed for use as insulator, heat spreaders, and compact heat exchanger cores. Such foams have voids that are typically of the order of 100 μm, and the pore walls are about 10 μm. The carbon in the foam may be graphitized by heat treatment during processing. The arrangement of graphene planes in graphitic foams is a function of position within the structure of the foam. Therefore, the thermal transport process is highly dependent on the microstructure. This results in bulk conductivities that range from 1 to 200W/mK. The bulk properties of such a porous medium are difficult to determine analytically, particularly in the case of high concentration of nonspherical pores, or when the porous material is anisotropic or nonhomogeneous. A finite element analysis has been developed to calculate the bulk thermal conductivity of carbon foams with anisotropic microstructure. The effective thermal conductivity is then evaluated by comparing the results of the analytical and numerical models.
Fatigue Strength Characterization of E-glass Fibers Using Fiber Bundle Test
Authors: Zhou Yuanxin , Mallick P. K.
Published: November 2004

An experimental approach has been developed to characterize the fatigue strength distribution of E-glass fibers using fiber bundle test. In this approach, survival probability, P, of the fiber bundles was first calculated from the stress reduction observed in strain-controlled fatigue tests. Based on the fiber bundle model, Weibull distribution and fatigue P –" – N curves, the fatigue strength exponent b, Weibull scale parameter σ0, and Weibull shape parameter β were then determined to characterize the fatigue strength distribution of E-glass fiber bundles. A numerical model, based on Monte-Carlo simulation, was also established to predict the load-controlled fatigue S–N diagram of E-glass fiber bundles. The simulated strain-cycle curves and stress-cycle curves based on the model developed were in good agreement with the test data.
Energy Dissipation Studies of Mg-based Nanocomposites Using an Innovative Circle-fit Approach
Authors: Srikanth Narasimalu , Hassan Syed Fida , Gupta Manoj
Published: November 2004

In the present study, energy dissipation capability of magnesium containing variable amounts of nanosize alumina (Al2O3) particle is investigated. Synthesis of materials was accomplished using a solidification processing route. Energy dissipation in the form of damping capacity was determined using a free–free type suspended beam arrangement coupled with a circle-fit approach. This technique is based on the classical vibration theory, by which the geometry and material properties of the metal matrix composites are related to resonant frequency and structural damping of the test specimen. Using the fact that the ratio of the vibration response to the applied force fits to a circle in the Argand plane for each resonant frequency of the test specimen, the damping factor and natural frequency is predicted accurately for the test specimen. The results revealed that an increase in the Al2O3 content upto 1.134 vol.% lead to an increase in the damping capacity upto 64%. Attempt is made to correlate the increase in damping with the increased volume fraction of nanosize Al2O3 particle in the composite samples.
The Network Studio
Authors: Théberge Paul
Published: November 2004

In recent years, various forces within and outside the music industry - record producers, hardware and software suppliers, and Internet service providers - have created techniques and tools that allow recording studios in remote locations to be networked in ever more complex and intimate ways. The effort behind the creation of the ‘network studio’ is, in part, the result of an overall progression in the historical development of the tools, architectures and practices of the contemporary recording studio. Studios do not exist in a musical or cultural vacuum, however: traditionally, music scenes, session musicians, and local aesthetics and practices have played an important role in the development of specific approaches to recording and have had an influence on the resulting sounds. But the rise of the network studio raises fundamental questions about such relationships and about the role of space and place in sound recording and, in this regard, can be considered as an expression of larger tendencies described within various theories of globalization. This paper addresses how the emergence of the network studio, with its emphasis on standardized technologies and practices and its reliance on the virtual space of network communications, may have an impact upon and/or work alongside conventional recording studio practices
Power Measurement as Sensitivity Analysis
Authors: Napel Stefan , Widgren Mika
Published: November 2004

This paper proposes a unified framework that integrates the traditional index-based approach and the competing non-cooperative approach to power analysis. It rests on a quantifiable notion of ex post power as the (counter-factual) sensitivity of the expected or observed outcome to individual players. Thus, it formalizes players’ marginal impact on outcomes in both cooperative and non-cooperative games, for both strategic interaction as well as purely random behavior. By taking expectations with respect to preferences, actions, and procedures, one obtains meaningful measures of ex ante power. Established power indices turn out to be special cases.
A Rational Theory of Socialist Public Ownership
Authors: Ferrero Mario
Published: November 2004

This paper asks why socialist economies were historically centered on public ownership of industry, despite its many drawbacks, and offers an explanation founded on rational individual choice. It first shows that the Marxian program of state socialism was subject to intense competition from alternative blueprints by the turn of the 20th century. It then argues that the superiority of the Marxian program lay in the contract enforcement property of an arrangement in which a politicized bureaucracy in charge of production was accountable to a party controlled by the workers. Formally, in a setting in which all participants are selfish and rational, the workers’ sole objective is redistribution, and an initial system choice has to be made. Party-state control of enterprises turns out to be the optimal contract between a principal (the workers) and its agent (the party) for a one-time transaction plagued by extreme informational asymmetry. Finally, modifications of this choice setting and implications for the decline of, and transition from, communism are discussed.
Developing Research Capacity and Collaboration in Primary Care and Social Care
Authors: Owen Jenny , Cooke Jo
Published: November 2004

Recent research provides evidence of collaboration between health and social care agencies in the UK, but without specifically discussing research capacity. Shared concerns include critiques of the dominant hierarchy of methods in healthcare research, and of simplistic approaches to the research-practice relationship. A study carried out in 2000-1 found evidence of poor research infrastructure within social services. However, there is also evidence of innovative developments, utilizing specific expertise in user involvement and action research. Study participants welcomed joint health and social care research training; barriers to participating in research included lack of confidence, limited time or training for research, low recognition for research activity and uneven supervision. We describe the initiatives that have developed in response to the study, and comment on developments in research governance. These present opportunities for increased collaboration at the primary health care/social care interface, although there is a need to maintain a pluralistic approach.
Belief, Optimism and Caring
Authors: Ryan Martin , Merighi Joseph R. , Healy Bill , Renouf Noel
Published: November 2004

What characterizes expertise in mental health social work? This article attempts to answer this question by reporting on the findings of a cross-national Australian and American study of social work practice expertise in mental health settings, particularly in working with people with long-term serious mental illness. The study identified expert practitioners through a peer-nomination process and asked each of them to describe a memorable practice situation in focus groups. These group interviews were transcribed verbatim and analysed using a constant comparative method. In the face of often complex and demanding work situations, these social workers demonstrated qualities specific to mental health social work that were designated as belief, optimism and caring. These three qualities are delineated and discussed in this article, as well as the implications for social work practice and education
Improving vibration weld joint strength through process and equipment modifications
Authors: Tucker B. , Bates P.J. , Tucker R. , Sidiropolous V.
Published: November 2004

Vibration welding is a process used to join thermoplastic components. Currently, under optimised low pressure welding, the weld strength of butt joints of unreinforced polymer can be equivalent to the strength of unwelded material. However, in short glass fibre reinforced polymer, the optimised weld strength is significantly lower than that of unwelded material and is closer to the strength of the resin matrix. This lower strength is attributable to the unfavourable orientation of the short glass fibres in the weld zone. The fibres tend to align parallel and in the plane of the weld zone and thus provide no reinforcement in the direction perpendicular to the weld zone. In the present work the impact of various modifications to the existing vibration welding technology was examined, with the objective of increasing the current achievable weld strength of glass reinforced nylon. The introduction of a secondary vibratory motion perpendicular to the weld plane during welding resulted in strengths 20% higher than those of samples welded using the standard vibration welding process.
Stress and distortion mitigation technique for welding titanium alloy thin sheet
Authors: Li J. , Guan Q. , Shi Y.W. , Guo D.L.
Published: November 2004

A stress and distortion mitigation technique for Gas Tungsten Arc Welding (GTAW) of titanium alloy Ti–6Al–4V thin sheet is presented. The proposed welding technique incorporates a trailing heat sink (an intense cooling source) with respect to the welding torch, and it is also called the Dynamically Controlled Low Stress No-Distortion (DC-LSND) technique. The development of this mitigation technique is based on both detailed welding process simulation using the advanced finite element technique and systematic laboratory experiments. The finite element method is used to investigate the detailed thermomechanical behaviour of the weld during conventional GTAW and DC-LSND GTAW. With detailed computational modelling, it is found that by the introduction of a heat sink at some distance behind the welding arc, a saddle shaped temperature field is formed as a result of the cooling effects of the heat sink; the lowest temperature exists in the zone where the heat sink is applied. High tensile action on the surrounding zone is generated by abrupt cooling and contraction of the metals beneath the heat sink, which increases the tensile plastic strain developed during the cooling process and decreases the compressive plastic strain developed in the heating process, and therefore mitigates the residual stresses and plastic strains within and near the weld. The experimental results confirmed the effectiveness of the DCLSND technique and the validity of the computational model. With a proper implementation of the DC-LSND technique, welding stress and distortion can be reduced or eliminated in welding titanium alloy Ti–6Al–4V thin sheet, while no appreciable detrimental effects are caused on the mechanical properties of welded joints by applying the heat sink in the GTAW process.
Fracture resistance of simulated heat affected zone areas in HSLA structural steel
Authors: Gliha V. , Vuherer T. , Ule B. , Vojvodic-Tuma J.
Published: November 2004

The fracture toughness of some areas in the multi-pass heat affected zone (HAZ) of a high strength low alloy (HSLA) structural steel was analysed in a straightforward way using precracked, cylindrical specimens tested on a conventional tensile machine. The specimens were made from samples with a simulated HAZ microstructure; however, the size of the samples was restricted by the limitations of the Gleeble machine. The brittleness of the samples was an indication of the detrimental effect of welding on their toughness. The specimens were not large enough for a direct KIc measurement over a wide testing temperature range; it was necessary to modify the results. The low fracture toughness and the substantial shift of fracture transition temperatures suggest that welding of the investigated steel could be a delicate procedure.
Joining of materials with millimetre-wave beam source
Authors: Lewis D. , Bruce R.W. , Imam M.A. , Fliflet A.W.
Published: November 2004

An 83 GHz gyrotron-based, millimetre-wave beam system is being used for a range of material processing. One very promising application of this technology is in joining of ceramic and ceramic composite materials and has unique advantages over competitive techniques. The significant advantage is localisation of heating, with the millimetre-wave beam controlled by reflective optics, permitting inexpensive fixturing and instrumentation and minimising thermal damage to components. Another is the possibility of depositing energy specifically in a narrow joint region, through a guided wave effect. A corollary advantage of the process is the possibility of very rapid thermal cycling during joining, minimising thermal degradation of materials being joined.
Physical properties of selected brazing filler metals
Authors: Arenas M.F. , Acoff V.L. , Reddy R.G.
Published: November 2004

A suitable selection of the filler metal is vital for producing satisfactory brazed joints. The wettability of brazing alloys with base metals depends on physical properties such as surface tension, density, melting point, and viscosity. Thermal conductivity and electrical resistivity are also important since the filler metal is frequently required to have similar values to those of the base metal. In the present paper, the physical properties of liquid alloys relevant to brazing have been evaluated. Six different filler metal systems were analysed, comprising alloys based on Ag, Al, Au, Cu, Ni, and Ti. Results show that the viscosity values for most binary brazing filler alloys are of the order of 2–8 mPa s, with Cu and Al alloys exhibiting the lowest viscosities. The surface tensions of brazing alloys vary from 800 to 1800 mN m-1, with the lowest surface tension values corresponding to the Ag and Al alloys. Thermal conductivity and electrical resistivity values fall in the range 10–200 W m-1 K-1 and 17–300 μΩ cm, respectively.
Control of Laves phase in Inconel 718 GTA welds with current pulsing
Authors: Janaki Ram G.D. , Venugopal Reddy A. , Prasad Rao K. , Madhusudhan Reddy G.
Published: November 2004

The presence of Nb rich Laves phase in Inconel 718 weld fusion zones is known to be detrimental to weld mechanical properties. In the present study, an attempt was made to control the formation of Laves phase in alloy 718 gas tungsten arc welds using pulsed current. Welds were produced in 2 mm thick sheets of the alloy with constant current and pulsed current and were subjected to post-weld solution treatment at 980°C followed by aging. Detailed microstructural studies and tensile tests at 650°C were conducted. The results show that the use of current pulsing (i) refines the fusion zone microstructure, (ii) reduces the amount of Laves phase and exerts a favourable influence on its morphology and (iii) improves the response of the fusion zone to post-weld heat treatment and weld tensile properties.
The use of modeling to understand the impact of screening on US mortality: examples from mammography and PSA testing
Authors: Feuer Eric J , Etzioni Ruth , Cronin Kathleen A , Mariotto Angela
Published: November 2004

Surveillance data represent a vital resource for understanding the impact of cancer control interventions on the population cancer burden. However, population cancer trends are a complex product of many factors, and estimating the contribution of any one of these factors can be challenging. Surveillance modeling is a technique for estimating the contribution of one or more interventions of interest to trends in disease incidence and mortality. In this article, we present several approaches to surveillance modeling of cancer screening interventions. We classify models as biological or epidemiological, depending on whether they model the full unobservable aspects of disease onset and progression, or models which reduce the complex process to simpler terms by summarizing portions of the disease process using mostly observed population level measures. We also describe differences between macrolevel models, microsimulation models and mechanistic models. We discuss procedures for model calibration and validation, and methods for presenting model results which are robust with respect to certain types of biased model estimates. As examples, we present several models of the impact of mammography screening on breast cancer mortality, and PSA screening on prostate cancer mortality. Both these examples are appropriate uses of surveillance modeling, even though for mammography there is extensive (although somewhat controversial) randomized trial evidence, whereas for PSA this biomarker has seen extensive use as a screening test prior to any controlled trial evidence of its efficacy. Some of the models presented here were developed as part of the National Cancer Institute’s Cancer Intervention and Surveillance Modeling Network.
Early detection of disease and scheduling of screening examinations
Authors: Lee Sandra , Huang Hui , Zelen Marvin
Published: November 2004

Special examinations exist for many chronic diseases, which can diagnose the disease while it is asymptomatic, with no signs or symptoms. The earlier detection of disease may lead to more cures or longer survival. This possibility has led to public health programs which recommend populations to have periodic screening examinations for detecting specific chronic diseases, for example, cancer, diabetes, cardiovascular disease and so on. Such examination schedules when embedded in a public health program are invariably costly and are ordinarily not chosen on the basis of possible trade-offs in costs and benefits for different screening schedules. The possible candidate number of examination schedules is so large that it is not feasible to carry out clinical trials to compare different schedules. Instead, this problem can be investigated by developing a theoretical model which can predict the eventual disease specific mortality for different examination schedules. We have developed such a model. It is a stochastic model which assumes that i) the natural history of the disease is progressive and ii) any benefit from earlier diagnosis is due to a change in the distribution of disease stages at diagnosis (stage shift). The model is general and can be applied to any chronic disease which satisfies our two basic assumptions. We discuss the basic ideas of schedule sensitivity and lifetime schedule sensitivity and its relation to the reduction in disease specific mortality. Our theory is illustrated by applications to breast cancer screening. The investigation of schedules compares not only examination schedules with equal intervals between examinations but also staggered schedules using the threshold method. (Examinations are carried out when an individual’s risk status reaches a preassigned threshold value.)
Multivariate distributions of clinical covariates at the time of cancer detection
Authors: Hanin L G , Yakovlev A Y
Published: November 2004

Many screening trials conducted in the past have generated a wealth of interesting data. These data represent an invaluable source of information for furthering our knowledge about the natural history of the disease. The traditional approach to modeling cancer screening tends to describe the process of tumor development in only one dimension, that is, the time natural history. A broader methodological idea is to construct a stochastic model of cancer development and detection that yields the multivariate distribution of observable variables at the time of diagnosis. By focusing on such multivariate observations, rather than just on the age of patients at diagnosis, this idea seeks to invoke an additional source of information (available only at the time of detection) in order to improve an estimation of unobservable quantitative parameters of cancer latency. In this article, we discuss modeling techniques that make the above-mentioned problems approachable. A special focus is placed on analytical tools for deriving joint distributions of clinical covariates at the time of cancer detection under an arbitrary screening protocol. In addition, some future research avenues and public health implications of the proposed approach are discussed.
Simulation-based parameter estimation for complex models: a breast cancer natural history modelling illustration
Authors: Chia Yen Lin , Salzman Peter , Plevritis Sylvia K , Glynn Peter W
Published: November 2004

Simulation-based parameter estimation offers a powerful means of estimating parameters in complex stochastic models. We illustrate the application of these ideas in the setting of a natural history model for breast cancer. Our model assumes that the tumor growth process follows a geometric Brownian motion; parameters are estimated from the SEER registry. Our discussion focuses on the use of simulation for computing the maximum likelihood estimator for this class of models. The analysis shows that simulation provides a straightforward means of computing such estimators for models of substantial complexity.
See One, Do One, Teach One: Advanced Technology in Medical Education
Authors: Vozenilek John , Huff J. Stephen , Reznek Martin , Gordon James A.
Published: November 2004

The concept of “learning by doing” has become less acceptable, particularly when invasive procedures and high‐risk care are required. Restrictions on medical educators have prompted them to seek alternative methods to teach medical knowledge and gain procedural experience. Fortunately, the last decade has seen an explosion of the number of tools available to enhance medical education: web‐based education, virtual reality, and high fidelity patient simulation. This paper presents some of the consensus statements in regard to these tools agreed upon by members of the Educational Technology Section of the 2004 AEM Consensus Conference for Informatics and Technology in Emergency Department Health Care, held in Orlando, Florida.

Findings:
Web‐based teaching: 1) Every ED should have access to medical educational materials via the Internet, computer‐based training, and other effective education methods for point‐of‐service information, continuing medical education, and training. 2) Real‐time automated tools should be integrated into Emergency Department Information Systems [EDIS] for contemporaneous education. Virtual reality [VR]: 1) Emergency physicians and emergency medicine societies should become more involved in VR development and assessment. 2) Nationally accepted protocols for the proper assessment of VR applications should be adopted and large multi‐center groups should be formed to perform these studies. High‐fidelity simulation: Emergency medicine residency programs should consider the use of high‐fidelity patient simulators to enhance the teaching and evaluation of core competencies among trainees.

Conclusions: Across specialties, patient simulation, virtual reality, and the Web will soon enable medical students and residents to… see one, simulate many, do one competently, and teach everyone.
Where's the Beef? The Promise and the Reality of Clinical Documentation
Authors: Davidson Steven J. , Zwemer Frank L. , Nathanson Larry A. , Sable Kenneth N. , Khan Abu N.G.A.
Published: November 2004

Physician‐generated emergency department clinical documentation (information obtained from clinician observations and summarized decision processes inclusive of all manner of electronic systems capturing, storing, and presenting clinical documentation) serves four purposes: recording of medical care and communication among providers; payment for hospital and physician; legal defense from medical negligence allegations; and symptom/disease surveillance, public health, and research functions. In the consensus development process described by Handler, these objectives were balanced with the consideration of efficiency, often evaluated as physician time and clinical documentation system costs, in recording the information necessary for their accomplishment. The consensus panel session participants and authors recommend that 1) clinical documentation be electronically retrievable; 2) selection and implementation be evidence‐based and grounded on valid metrics (research is needed to identify these metrics); 3) the user interface be crafted to promote clinical excellence through high‐quality information collection and efficient charting techniques; 4) the priorities for integration of clinical information be standardized and implemented within enterprises and across health and information systems; 5) systems use accepted standards for bidirectional, real‐time clinical data exchange, without limiting the location or number of simultaneous users; 6) systems fully utilize existing electronic sources of specific patient information and general medical knowledge; 7) systems automatically and reliably capture appropriate data that support electronic billing for emergency department services; and 8) systems promote bedside documentation and mobile access.
Disparate Systems, Disparate Data: Integration, Interfaces, and Standards in Emergency Medicine Information Technology
Authors: Barthell Edward N. , Coonan Kevin , Finnell John , Pollock Dan , Cochrane Dennis
Published: November 2004

As part of the broader informatics consensus initiative sponsored by Academic Emergency Medicine, this report addresses the issues of integration, interfaces, and data standards and how they are relevant to information management in emergency medicine. The purpose of this report, and the workgroup that contributed to its content, is to provide emergency physicians and other stakeholders in the emergency informatics community a sense of direction as they design, build, and/or choose systems. Problems are identified, strategies to address these problems are discussed, and consensus recommendations are provided.
Information Technology Principles for Management, Reporting, and Research
Authors: Gillam Michael , Rothenhaus Todd , Smith Vernon , Kanhouwa Meera
Published: November 2004

Information technology holds the promise to enhance the ability of individuals and organizations to manage emergency departments, improve data sharing and reporting, and facilitate research. The Society for Academic Emergency Medicine (SAEM) Consensus Committee has identified nine principles to outline a path of optimal features and designs for current and future information technology systems. The principles roughly summarized include the following: utilize open database standards with clear data dictionaries, provide administrative access to necessary data, appoint and recognize individuals with emergency department informatics expertise, allow automated alert and proper identification for enrollment of cases into research, provide visual and statistical tools and training to analyze data, embed automated configurable alarm functionality for clinical and nonclinical systems, allow multiexport standard and format configurable reporting, strategically acquire mission‐critical equipment that is networked and capable of automated feedback regarding functional status and location, and dedicate resources toward informatics research and development. The SAEM Consensus Committee concludes that the diligent application of these principles will enhance emergency department management, reporting, and research and ultimately improve the quality of delivered health care.
Clinical Information Systems: Instant Ubiquitous Clinical Data for Error Reduction and Improved Clinical Outcomes
Authors: Feied Craig F. , Handler Jonathan A. , Smith Mark S. , Gillam Michael , Kanhouwa Meera , Rothenhaus Todd , Conover Keith , Shannon Tony
Published: November 2004

Immediate access to existing clinical information is inadequate in current medical practice; lack of existing information causes or contributes to many classes of medical error, including diagnostic and treatment error. A review of the literature finds ample evidence to support a description of the problems caused by data that are missing or unavailable but little evidence to support one proposed solution over another. A primary recommendation of the Consensus Committee is that hospitals and departments should adopt systems that provide fast, ubiquitous, and unified access to all types of existing data. Additional recommendations cover a variety of related functions and operational concepts, from backups and biosurveillance to speed, training, and usability.
Evaluation of Emergency Medical Text Processor, a System for Cleaning Chief Complaint Text Data
Authors: Travers Debbie A. , Haas Stephanie W.
Published: November 2004

Objectives: Emergency Medical Text Processor (EMT‐P) version 1, a natural language processing system that cleans emergency department text (e.g., chst pn, chest pai), was developed to maximize extraction of standard terms (e.g., chest pain). The authors compared the number of standard terms extracted from raw chief complaint (CC) data with that for CC data cleaned with EMT‐P and evaluated the accuracy of EMT‐P. Methods: This cross‐sectional observation study included CC text entries for all emergency department visits to three tertiary care centers in 2001. Terms were extracted from CC entries before and after cleaning with EMT‐P. Descriptive statistics included number and percentage of all entries (tokens) and all unique entries (types) that matched a standard term from the Unified Medical Language System (UMLS). An expert panel rated the accuracy of the CC–UMLS term matches; inter‐rater reliability was measured with κ. Results: The authors collected 203,509 CC entry tokens, of which 63,946 were unique entry types. For the raw data, 89,337 tokens (44%) and 5,081 types (8%) matched a standard term. After EMT‐P cleaning, 168,050 tokens (83%) and 44,430 types (69%) matched a standard term. The expert panel reached consensus on 201 of the 222 CC–UMLS term matches reviewed (κ= 0.69–0.72). Ninety‐six percent of the 201 matches were rated equivalent or related. Thirty‐eight percent of the nonmatches were found to match UMLS concepts.Conclusions: EMT‐P version 1 is relatively accurate, and cleaning with EMT‐P improved the CC–UMLS term match rate over raw data. The authors identified areas for improvement in future EMT‐P versions and issues to be resolved in developing a standard CC terminology.
Using Online Analytical Processing to Manage Emergency Department Operations
Authors: Gordon Bradley D. , Asplin Brent R.
Published: November 2004

The emergency department (ED) is a unique setting in which to explore and evaluate the utility of information technology to improve health care operations. A potentially useful software tool in managing this complex environment is online analytical processing (OLAP). An OLAP system has the ability to provide managers, providers, and researchers with the necessary information to make decisions quickly and effectively by allowing them to examine patterns and trends in operations and patient flow. OLAP software quickly summarizes and processes data acquired from a variety of data sources, including computerized ED tracking systems. It allows the user to form a comprehensive picture of the ED from both system‐wide and patient‐specific perspectives and to interactively view the data using an approach that meets his or her needs. This article describes OLAP software tools and provides examples of potential OLAP applications for care improvement projects, primarily from the perspective of the ED. While OLAP is clearly a helpful tool in the ED, it is far more useful when integrated into the larger continuum of health information systems across a hospital or health care delivery system.
Emergency Department Digital Radiology: Moving from Photos to Pixels
Authors: White Faber A. , Zwemer Frank L. , Beach Christopher , Westesson Per‐Lennart , Fairbanks Rollin J. , Scialdone Gary
Published: November 2004

Emergency department (ED) patient care relies heavily on radiologic imaging. As advances in technologic innovation continue to present opportunities to streamline and simplify the delivery of care, emergency medicine (EM) practitioners face the challenge of transitioning from a system of primarily film‐based radiography to one that utilizes digitized images. The move to digital radiology can result in enhanced quality of patient care, reduction of errors, and increased ED efficiency; however, making this transition will necessarily involve changes in EM practice. As the technology evolves, digital radiology will gradually become ingrained into everyday practice because of these and other notable benefits; however, EM practitioners will need to overcome several challenges to make the transition smoothly and consider the potential impacts that this change will have on ED workflow. The authors discuss the benefits, challenges, and other operational considerations involved with the ED implementation of digital radiology and close by presenting guiding principles for current and future users. Despite the unresolved issues, digital radiology will mature as a technology and improve EM practice, making it one of the great information technology advances in EM.