bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-term hypoxia alters ovine fetal endocrine and physiological responses to hypotension
Authors: Adachi Keiichi , Umezaki Hikaru , Kaushal Kanchan M. , Ducsay Charles A.
Published: March 2004

Exposure to long-term hypoxia (LTH) results in altered cortisol responses in the ovine fetus. The present study was designed to test the hypothesis that LTH alters adrenal responsiveness to fetal hypotension. Pregnant ewes were maintained at high altitude (3,820 meters) from day 30 of gestation. Normoxic control and LTH fetuses were catheterized on day 132 of gestation. In the LTH group, maternal Po2 was maintained comparable to that observed at altitude (∼60 mmHg) by nitrogen infusion through a tracheal catheter. On day 137, fetuses received a 5-h saline infusion followed by infusion of sodium nitroprusside to reduce fetal arterial pressure by 30–35% for 10 min. The study was repeated on day 139 of gestation with a continuous cortisol infusion (10 μg/min). Hypothalamic and pituitary tissues were collected from additional fetuses for assessment of glucocorticoid receptors. During the saline infusion in response to hypotension, plasma ACTH increased over preinfusion mean values in both groups ( P < 0.05). Plasma cortisol concentrations increased in both groups concomitant with increased ACTH secretion. However, peak values in the LTH fetuses were significantly higher compared with controls ( P < 0.05). During the cortisol infusion, the ACTH response was eliminated in both groups, with ACTH levels significantly lower in the LTH group ( P < 0.05). Glucocorticoid receptor binding was not different between groups. These results demonstrate an enhanced cortisol response to hypotension in LTH fetuses that does not appear to be the result of an increase in negative feedback sensitivity of the hypothalamic-pituitary-adrenal axis.
Steady-State Levels of Monoamines in the Rat Lumbar Spinal Cord: Spatial Mapping and the Effect of Acute Spinal Cord Injury
Authors: Noga Brian R. , Pinzon Alberto , Mesigil Riza P. , Hentall Ian D.
Published: March 2004

Monoamines in the spinal cord are important in the regulation of locomotor rhythms, nociception, and motor reflexes. To gain further insight into the control of these functions, the steady-state extracellular distribution of monoamines was mapped in the anesthetized rat's lumbar spinal cord. The effect of acute spinal cord lesions at sites selected for high resting levels was determined over ∼1 h to estimate contributions to resting levels from tonic descending activity and to delineate chemical changes that may influence the degree of pathology and recovery after spinal injury. Measurements employed fast cyclic voltammetry with carbon fiber microelectrodes to give high spatial resolution. Monoamine oxidation currents, sampled at equal vertical spacings within each segment, were displayed as contours over the boundaries delineated by histologically reconstructed electrode tracks. Monoamine oxidation currents were found in well defined foci, often confined within a single lamina. Larger currents were typically found in the dorsal or ventral horns and in the lateral aspect of the intermediate zone. Cooling of the low-thoracic spinal cord led to a decrease in the oxidation current (to 71–85% of control) in dorsal and ventral horns. Subsequent low-thoracic transection produced a transient increase in signal in some animals followed by a longer lasting decrease to levels similar to or below that with cooling (to 17–86% of control values). We conclude that descending fibers tonically release high amounts of monoamines in localized regions of the dorsal and ventral horn of the lumbar spinal cord at rest. Lower amounts of monoamines were detected in medial intermediate zone areas, where strong release may be needed for descending activation of locomotor rhythms.
Human Midbrain Sensitivity to Cognitive Feedback and Uncertainty During Classification Learning
Authors: Aron A. R. , Shohamy D. , Clark J. , Myers C. , Gluck M. A. , Poldrack R. A.
Published: March 2004

Mesencephalic dopaminergic system (MDS) neurons may participate in learning by providing a prediction error signal to their targets, which include ventral striatal, orbital, and medial frontal regions, as well as by showing sensitivity to the degree of uncertainty associated with individual stimuli. We investigated the mechanisms of probabilistic classification learning in humans using functional magnetic resonance imaging to examine the effects of feedback and uncertainty. The design was optimized for separating neural responses to stimulus, delay, and negative and positive feedback components. Compared with fixation, stimulus and feedback activated brain regions consistent with the MDS, whereas the delay period did not. Midbrain activity was significantly different for negative versus positive feedback (consistent with coding of the “prediction error”) and was reliably correlated with the degree of uncertainty as well as with activity in MDS target regions. Purely cognitive feedback apparently engages the same regions as rewarding stimuli, consistent with a broader characterization of this network.
Inhibitors of Protein Kinase Signaling Pathways
Authors: Force Thomas , Kuida Keisuke , Namchuk Mark , Parang Keykavous , Kyriakis John M.
Published: March 2004

Protein kinases are enzymes that covalently modify proteins by attaching phosphate groups (from ATP) to serine, threonine, and/or tyrosine residues. In so doing, the functional properties of the protein kinase’s substrates are modified. Protein kinases transduce signals from the cell membrane into the interior of the cell. Such signals include not only those arising from ligand-receptor interactions but also environmental perturbations such as when the membrane undergoes mechanical deformation (ie, cell stretch or shear stress). Ultimately, the activation of signaling pathways that use protein kinases often culminates in the reprogramming of gene expression through the direct regulation of transcription factors or through the regulation of mRNA stability or protein translation. Protein kinases regulate most aspects of normal cellular function. The pathophysiological dysfunction of protein kinase signaling pathways underlies the molecular basis of many cancers and of several manifestations of cardiovascular disease, such as hypertrophy and other types of left ventricular remodeling, ischemia/reperfusion injury, angiogenesis, and atherogenesis. Given their roles in such a wide variety of disease states, protein kinases are rapidly becoming extremely attractive targets for drug discovery, probably second only to heterotrimeric G protein-coupled receptors (eg, angiotensin II). Here, we will review the reasons for this explosion in interest in inhibitors of protein kinases and will describe the process of identifying novel drugs directed against kinases. We will specifically focus on disease states for which drug development has proceeded to the point of clinical or advanced preclinical studies.
Wessex Estate: Recollections of British Military and Imperial History in the Heart of Singapore
Authors: De Koninck Rodolphe
Published: March 2004

Although the island Republic of Singapore has been submitted to a systematic territorial revolution since the 1960s, some of its urban heritage has been preserved. This is the case with Wessex Estate, a quiet residential neighbourhood located in the low hills extending on the western flank of the central urban area. Made up of less than a dozen bungalows and 26 small blocks of flats, Wessex Estate is of no particular architectural interest, but it does represent a heritage through the names borne by the blocks of flats. Clearly printed on the façades of the 26 blocks of flats, these names all refer to military feats of British history. The study locates and briefly describes these events, several of which took place on European fronts, as far back as the early 18th century (such as Ramilies, Blenheim), others throughout the British Empire, starting from the middle of the same century (such as Plassey, Quebec, Khartoum, Pegu). Built just prior to or just following WWII, it seems that the flats housed non-commissioned British officers during the Malayan Emergency (1948–1960). Their names refer to battles or theatres of war in all of which a given British regiment, the 67th or South Hampshire Regiment, might have been involved. Whatever the case, it remains somewhat remarkable that so many reminders of the colonial past, even a good number with "no natural connection" to Singapore, have remained prominent in this city-state otherwise apparently prone to sever "colonial apron strings".
Health Hazards and Labour Laws in Bangladesh: A Narrative-based Study on Women Garment Workers
Authors: Absar Syeda Sharmin
Published: March 2004

There are labour laws pertinent to health issues of garment workers in Bangladesh. The laws cover work hours, wages, sick leave, maternity leave and benefits, compensation and other working environment related issues. Because of the lack of implementation and/or violation of the laws, workers often suffer from health hazards both at work and at home. The problem is compounded by the fact that workers are unaware of many of the laws and the benefits they are entitled to because of lack of education and resources. The Bangladesh government, garment employers and different international and national NGOs have important roles to play in reducing the health hazards of workers. The paper discusses different types of illnesses and through narratives of women garment workers explores health hazards experienced by them. It also suggests solutions for policy-makers, NGO activists, employers and workers.
Organising Discontent: NGOs for Southeast Asian Migrant Workers in Hong Kong
Authors: Sim Amy
Published: March 2004

In the five decades after World War II, diverse non-governmental organisations (NGOs) have proliferated in different parts of the world to address a variety of issues ranging from humanitarian aid to human rights. At the same time, the volume of vitriolic criticisms levelled against them have also risen. This paper seeks to identify the types of changes NGOs are able to bring about in society. By adapting and applying David Korten's (1990) typology of NGOs, the author undertakes a comparative analysis of NGOs in Hong Kong that are involved with the improvement of foreign workers' rights and welfare. The argument is that the different strategies adopted by the NGOs have wrought social changes in diverse ways, from the provision of welfare assistance to the mass mobilisation of workers, in both sending and receiving countries. This is an example of the catalytic role of NGOs in contributing to a trans-border "community of sentiment" (Appadurai, 1990).
Hugo Grotius in Context: Van Heemskerck's Capture of the Santa Catarina and its Justification in De Jure Praedae (1604-1606)
Authors: Van Ittersum Martine Julia
Published: March 2004

This article reconstructs Jacob van Heemskerck's second voyage to the East Indies and his capture of the Portuguese merchantman

Santa Catarina

on 25 February 1603. It incorporates important new archival evidence like Van Heemskerck's letter to the directors of the Dutch East India Company of 27 August 1603, and the original text of the verdict of the Amsterdam Admiralty Court, which confiscated the

Santa Catarina

on 4 September 1604. It has long been known that the Dutch jurist Hugo Grotius (1583-1645) wrote

De Jure Praedae

in defense of the ship's seizure and at the explicit request of the directors of the Dutch East India Company. Historians have failed to recognise, however, that Grotius' conceptualisation of natural rights and natural law in

De Jure Praedae

is based to a large extent on Van Heemskerck's own justification of privateering. A key notion of Grotius' rights theories - the individual's right to punish transgressors of the natural law in the absence of an independent and effective judge - follows logically from Van Heemskerck's reasoned decision to assault the

Santa Catarina

in revenge for Portuguese mistreatment of Dutch merchants in the East Indies. As shown by recent work in international relations theory - notably Edward Keene's

Beyond the Anarchical Society: Grotius, Colonialism and Order in World Politics

(Keene, 2002) - the natural law and natural rights theories that Grotius formulated in

De Jure Praedae

cannot be divorced from Dutch imperialism and colonialism in the early modern period.
The Voice and the Listener: Feminist Theory and the Sociological Canon
Authors: Adelman Miriam
Published: March 2004

This paper discusses the relationship between feminist theory and the contemporaneous efforts to re-think basic sociological categories occurring in the aftermath of the 1960s' social movements, primarily in the US and Europe. I examine the questions that were being asked by both feminist thinkers and several major sociological theorists (Richard Sennett, Alain Touraine and Anthony Giddens). I attempt to evaluate the extent to which the latter were initially, and in later work, willing or interested in hearing and incorporating feminist voices in their re-thinking of the field. I identify a tendency to circumscribe feminist contributions to particular substantive areas - those related specifically to gender, or to sexuality, subjectivity and personal life - with, as Susan Bordo has pointed out, much less receptivity to feminist theorists' contributions to more general "cultural critique" and issues which are considered to be "macro-level". I also engage in a brief discussion of how these problems have been reproduced in Brazilian social sciences and the uneasy relationship between feminist scholarship and academic sociology in Brazil today.
Comparative expressed sequence hybridization studies of hairy cell leukemia show uniform expression profile and imprint of spleen signature
Authors: Vanhentenrijk Vera , De Wolf-Peeters Chris , Wlodarska Iwona
Published: March 2004

Comparative expressed sequence hybridization (CESH) to chromosomes is a recently introduced technique that identifies chromosomal regions corresponding to a differential gene expression. This technique is analogous to comparative genomic hybridization (CGH) that detects genomic imbalances. We applied CESH for the study of hairy cell leukemia (HCL), a disorder with a largely unknown expression profile. Twelve HCL cases with spleen involvement were investigated by CESH and CGH. While the latter analysis identified only a few nonrecurrent genomic imbalances, CESH showed a consistent expression profile in all HCL cases. In addition, pairing normal spleen with normal lymph node, a “spleen signature” was established by CESH. This signature most likely reflects the expression profile of spleen-specific components, such as the sinusoidal lining cells from the red pulp and the marginal zone B cells from the white pulp. Imprint of the spleen signature was found in the HCL expression profile, suggesting that HCL may originate from a particular B-cell subset present in these splenic components. Besides pairing HCL with normal lymph node and spleen, we identified an “HCL signature” comprising several chromosome regions with altered expression. The most significantly underexpressed regions include 3p24, 3p21, 3q13.3-q22, 4p16, 11q23, 14q22-q24, 15q21-q22, 15q24-q25, and 17q22-q24; and 13q31 and Xq13.3-q21 were the most significantly overexpressed. These regions possibly harbor genes related to the biology and the pathogenesis of HCL. Their identification warrants further molecular investigations.
Primary human CD34+ hematopoietic stem and progenitor cells express functionally active receptors of neuromediators
Authors: Steidl Ulrich , Bork Simone , Schaub Sebastian , Selbach Oliver , Seres Janette , Aivado Manuel , Schroeder Thomas , Rohr Ulrich-Peter , Fenk Roland , Kliszewski Slawomir , Maercker Christian , Neubert Peter , Bornstein Stefan R. , Haas Helmut L. , Kobbe Guido , Tenen Daniel G. , Haas Rainer , Kronenwett Ralf
Published: March 2004

Recently, overlapping molecular phenotypes of hematopoietic and neuropoietic cells were described in mice. Here, we examined primary human CD34+ hematopoietic stem and progenitor cells applying specialized cDNA arrays, real-time reverse-transcriptase–polymerase chain reaction (RT-PCR), and fluorescent-activated cell sorter (FACS) analysis focusing on genes involved in neurobiologic functions. We found expression of vesicle fusion and motility genes, ligand- and voltage-gated ion channels, receptor kinases and phosphatases, and, most interestingly, mRNA as well as protein expression of G protein–coupled receptors of neuromediators (corticotropin-releasing hormone 1 [CRH 1] and CRH 2 receptors, orexin/hypocretin 1 and 2 receptors, GABAB receptor, adenosine A2B receptor, opioid κ1 and μ1 receptors, and 5-HT 1F receptor). As shown by 2-color immunofluorescence, the protein expression of these receptors was higher in the more immature CD38dim than in the CD38bright subset within the CD34+ population, and completely absent in fully differentiated blood cells, suggesting that those receptors play a role in developmentally early CD34+ stem and progenitor cells. The intracellular concentration of cyclic adenosine monophosphate (cAMP) in CD34+ cells was diminished significantly upon stimulation of either CRH or orexin receptors, indicating that those are functionally active and coupled to inhibitory G proteins in human hematopoietic cells. In conclusion, these findings suggest a molecular interrelation of neuronal and hematopoietic signaling mechanisms in humans.
Two zebrafish Notch-dependenthairy/Enhancer-of-split-relatedgenes,her6andher4, are required to maintain the coordination of cyclic gene expression in the presomitic mesoderm
Authors: Pasini Andrea , Jiang Yun-Jin , Wilkinson David G.
Published: March 2004

Alterations of the Delta/Notch signalling pathway cause multiple morphogenetic abnormalities in somitogenesis, including defects in intersomitic boundary formation and failure in maintenance of somite regularity. Notch signalling has been implicated in establishing the anteroposterior polarity within maturing somites and in regulating the activity of a molecular segmentation clock operating in the presomitic mesoderm. The pleiotropy of Notch signalling obscures the roles of this pathway in different steps of somitogenesis. One possibility is that distinct Notch effectors mediate different aspects of Notch signalling. In this study,we focus on two zebrafish Notch-dependent hairy/Enhancer-of-split-related transcription factors, Her6 and Her4, which are expressed at the transition zone between presomitic mesoderm and the segmented somites. The results of overexpression/gain-of-function and of morpholino-mediated loss-of-function experiments show that Her6 and Her4 are Notch signalling effectors that feedback on the clock and take part in the maintenance of cyclic gene expression coordination among adjacent cells in the presomitic mesoderm.
Elastic-plastic-creep cyclic loading of beams using the Prager kinematic hardening model
Authors: Mahbadi H , Gowhari A. R , Eslami M. R
Published: March 2004

The Prager kinematic hardening model is used to evaluate the elastic-plastic-creep cyclic loading of beams under thermal and mechanical loads. The material of the structure used in this article is assumed to follow a non-linear strain-hardening characteristic. The material's strain-hardening curves in tension and compression are assumed to be identical for isotropic material. A new iterative method is used to calculate the stresses and plastic strains in the structure due to the cyclic loadings. The results of the analysis are checked against the known experimental data. The thermal and mechanical stresses are categorized into load- and deformation-controlled stresses. When creep deformation is considered, the load-controlled stresses result in ratcheting, and the deformation-controlled stresses result in shakedown behaviour.
Multiple-crack analysis with the quasi-higher-order symmetric Galerkin boundary element method
Authors: Lie S-T , Xu K , Cen Z
Published: March 2004

This paper describes the application of the symmetric Galerkin boundary element method (SGBEM) for the analysis of a two-dimensional linear elastic crack problem. The direct SGBEM for the multiple-crack problem is derived using the Betti reciprocal theorem, resulting in a completely symmetric matrix. The auxiliary fictitious state is used to obtain the equations. This approach can deal with any number of traction-free cracks within a single domain. Two-stage interpolation method called the ‘quasi-higher-order element method’ (QHOEM) is then proposed to solve the double integrals. In the initial stage, it uses higher-order elements to interpolate the field variables and, for the numerical integration involved, it further uses interpolation functions to decompose the higher-order elements into lower-order elements so that the existing analytical integration can be applied. Thus, it can be embedded into the present codes with ease and also reduces the computational cost. A finite rectangular plate containing a slanting crack and a kinked crack has been analysed to check the accuracy of the proposed method. A load-carrying fillet welded joint containing several cracks is then analysed, and the stress intensity factors at the crack tips are found to be in complete agreement with the dual-boundary-element method results.
Measurement of microslips of subsurface fatigue crack faces due to rolling loads
Authors: Morbarigazzi C , Stupnicki J
Published: March 2004

The development of accurate numerical models of the growth of subsurface fatigue cracks due to rolling load needs reliable experimental data on the actual interactions between the crack faces. The distribution of microslips that occur between the crack faces and the interaction between the crack faces as a function of the magnitude and the position of the load with respect to the crack tip are of particular interest. In this study, the microslips of the faces of a subsurface fatigue crack developed in a railhead made of 900A steel were measured by the grating holographic interferometry (GHI) technique. Reconstruction of each double-exposed hologram made it possible to obtain four interferograms at multiple off-axis angles. On the basis of the interferograms, two-dimensional maps of the displacement vector components were determined, making it possible to calculate the distribution over the crack length of the crack face microslips and the crack opening and closing. A specifically designed experimental stand allowed the application of a stepwise increase in the normal load and consequently stepwise rolling of a constant load along the edge of the specimen.
Cracked piping branch junctions under pressure and in-plane bending: Comparison of experimental plastic loads and finite element limit loads
Authors: Lynch M. A , Moreton D. N , Moffat D. G
Published: March 2004

A series of piping branch junctions has been manufactured by computer numeric control (CNC) machining, fully instrumented and subjected to in-plane bending or internal pressure tests. For some of the junctions, crack-like defects have been introduced at strategic locations. All data recorded during the loading of the branch junctions have been used in an attempt to establish an acceptable plastic load for each junction using the twice-elastic slope method. Measured plastic loads and maximum experimental loads achieved are compared with finite element (FE) predictions of limit loads.
Three-dimensional representation of normal stress magnitude with applications to hydrobulge forming
Authors: He Z. B , Wang Z. R , Teng B. G
Published: March 2004

A new graphical representation of normal stress at one point and its corresponding deviatoric stress state are presented for the first time in this paper. The relationship between the normal stress figures and the deformation types is analysed as well. In addition, the internal hydrobulging forming process is analysed by using the normal stress figure.
On the influence of in-plane displacements on the stability of plate assemblies
Authors: Minutolo V , Ruocco E , Migliore M. R
Published: March 2004

The present paper extends the Koiter-type initial post-buckling analysis for a prismatic plate in order to evaluate the critical load corresponding to modes that involve unlikely in-plane displacements that cannot be obtained when the von Karman strain displacement relationship is used. In-plane displacements cannot be neglected with respect to out-of-plane displacements when stiffened plates undergo global buckling. The consistency of the model is discussed, and several numerical tests are reported. It appears that meaningful reduction of critical load in comparison with the classical von Karman model can occur; moreover the use of a semi-analytical model makes the perturbation approach insensitive to numerical instabilities occurring in the evaluation of the post-buckling behaviour and allows the use of very low-cost discretization meshes.
The Cyclo[(disilanylene)(butadiyne)]s [(i-Pr)2Si(i-Pr)2SiC≡CC≡C]n (n = 2–4)
Authors: Negishi Keisuke , Unno Masafumi , Matsumoto Hideyuki
Published: March 2004

The new type of the twelve- to twenty-four-membered rings [(i-Pr)2Si(i-Pr)2SiC≡CC≡C]n (1, n = 2; 2, n = 3; 3, n = 4) were synthesized and the molecular structures of 1 and 2 were analyzed by X-ray crystallography. The compounds show unusual electronic properties due to the interaction of the C≡C π orbitals with the Si–Si σ bonds.
Centile Charts II: Alternative Nonparametric Approach for Establishing Time-Specific Reference Centiles and Assessment of the Sample Size Required
Authors: Griffiths Jenny K , Iles Terence C , Koduah Martin , Nix Arthur B J
Published: March 2004

Background: Reference intervals, and more generally centile estimates, are used to characterize a reference population for the purposes of interpreting an individual patient’s clinical measurement. We describe methods of calculating reference intervals where these centiles vary with a covariate, usually age or time.

Methods: The US Food and Drug Administration and the IFCC have made recommendations on two approaches: the parametric approach, which models the structural characteristics of the data set with a theoretical distribution, and the nonparametric approach, which makes no particular assumption about this structure. In this report we propose a nonparametric procedure that relies on the principles of regression and show how sample size determination can be assessed. We also show how the sample size calculation is influenced by the distribution of the times measured.

Results: We illustrated our method on three data sets and compared the results for our proposed nonparametric method with parametric estimates. We showed that the bias is reduced and that the nonparametric method is less likely to produce fluctuating profiles.

Conclusions: To achieve adequate precision the sample size needs to be larger than 120, as has often been recommended. If there is doubt about the parametric model, then threshold sample sizes may need to be as high as 500.
Simple Technique for Internal Control of Real-Time Amplification Assays
Authors: Burggraf Siegfried , Olgemöller Bernhard
Published: March 2004

Background: In real-time PCR assays, the most accurate way to identify false-negative results, e.g., those caused by PCR inhibitors, is to add to samples an internal control that will be coamplified with the target (e.g., pathogen) DNA. Current internal control procedures, however, which usually involve the introduction of a DNA fragment, are complex, time-consuming, and expensive.

Methods: Single-stranded oligonucleotides, which contain little more than primer and probe binding sites, were used as internal controls in real-time PCR assays. Mismatches were included in the probe-binding region of the internal control oligonucleotide (ICO) to prevent probe–control hybridization during the fluorescence acquisition step of the PCR. Amplified ICOs were detected by melting point analysis. ICOs could be added directly to the sample material before DNA extraction.

Results: To demonstrate the feasibility of the new approach, we designed ICOs for the LightCycler hybridization probe assays for Mycobacterium tuberculosis complex, hepatitis B virus, herpes simplex virus, and varicella zoster virus. In each case, the controls did not interfere with detection of the pathogen, but were clearly detectable during a subsequent melting point analysis.

Conclusions: A single-stranded oligonucleotide that mimics the target region of the pathogen but is clearly distinguishable from the target during melting point analysis can serve as a simple, cost-effective internal control for real-time amplification assays. Such control oligonucleotides are easy to design and inexpensive. A costly second probe system is not necessary. Moreover, the internally controlled assay uses only one fluorescence detection channel of the instrument, leaving the second channel free for multiplex applications.
Empirical Assessment of Expertise
Authors: Weiss David J. , Shanteau James
Published: March 2004

The assessment of expertise is vital both in practical situations that call for expert judgment and in theoretical research on the psychology of experts. It can be difficult, however, to determine whether a judge is in fact performing expertly. Our goal was to develop an empirical measure of expert judgment. We argue that two necessary characteristics of expertise are discrimination of the various stimuli in the domain and consistent treatment of similar stimuli. We combine measures of these characteristics to form a ratio we call the Cochran-Weiss-Shanteau (CWS) index of expertise. The proposed index was demonstrated using two studies that distinguished experts from nonexperts based on their judgmental performance. The index provides new insights into expertise and offers a partial definition of expertise that may be useful in a variety of theoretical and applied settings. Potential applications of this research include selection, training, and evaluation of experts and of expert-machine systems.
Mathematical Modeling of Decision Making: A Soft and Fuzzy Approach to Capturing Hard Decisions
Authors: Dorsey David W. , Coovert Michael D.
Published: March 2004

This research focuses on a modeling approach and set of mathematical tools that were derived from research on intelligence systems, namely fuzzy system modeling. This study systematically evaluates these tools as an approach for modeling human decision making, contrasting the approach with more traditional methods based on regression. The research was conducted using experts and a simulated task environment related to allocating rewards in the form of merit pay. The results indicate that fuzzy system models generally perform as well as or better than both linear and nonlinear regression methods in terms of model fit. These results are discussed in terms of issues regarding modeling precision versus parsimony, the value of adaptive modeling techniques, empirical versus subjective approaches to model building, and individual differences in judgment strategies. Potential applications of this research include using the modeling approach studied to build higher-fidelity models that yield new insights and a better understanding of decision-making strategies and environments.
Control and Perception of Balance at Elevated and Sloped Surfaces
Authors: Simeonov Peter I. , Hsiao Hongwei , Dotson Brian W. , Ammons Douglas E.
Published: March 2004

Understanding roof-work-related risk of falls and developing low-cost, practical engineering controls for reducing this risk remain in high demand in the construction industry. This study investigated the effects of the roof work environment characteristics of surface slope, height, and visual reference on standing balance in construction workers. The 24 participants were tested in a laboratory setting at 4 slopes (0°, 18°, 26°, and 34°), 2 heights (0, 3 m), and 2 visual conditions (with and without visual references). Postural sway characteristics were calculated using center of pressure recordings from a force platform. Workers' perceptions of postural sway and instability were also evaluated. The results indicated that slope and height synergistically increased workers' standing postural instability. Workers recognized the individual destabilizing effects of slope and height but did not recognize the synergistic effect of the two. Visual references significantly reduced the destabilizing effects of height and slope. Actual and potential applications of this research include the use of temporary level work surfaces and proximal vertical reference structures as postural instability control measures during roofing work
Time Estimation during Prolonged Sleep Deprivation and Its Relation to Activation Measures
Authors: Miró Elena , Cano M. Carmen , Espinosa-Fernández Lourdes , Buela-Casal Gualberto
Published: March 2004

This is the first study to analyze variations in time estimation during 60 h of sleep deprivation and the relation between time estimation performance and the activation measures of skin resistance level, body temperature, and Stanford Sleepiness Scale (SSS) scores. Among 30 healthy participants 18 to 24 years of age, for a 10-s interval using the production method, we found a lengthening in time estimations that was modulated by circadian oscillations. No differences in gender were found in the time estimation task during sleep deprivation. The variations in time estimation correlated significantly with body temperature, skin resistance level, and SSS throughout the sleep deprivation period. When body temperature is elevated, indicating a high level of activation, the interval tends to be underestimated, and vice versa. When the skin resistance level or SSS is elevated (low activation), time estimation is lengthened, and vice versa. This lengthening is important because many everyday situations involve duration estimation under moderate to severe sleep loss. Actual or potential applications of this research include transportation systems, emergency response work, sporting activities, and industrial settings in which accuracy in anticipation or coincidence timing is important for safety or efficiency.
Computational Modeling of Foveal Target Detection
Authors: Witus Gary , Ellis R. Darin
Published: March 2004

This paper presents the VDM 2000, a computational model of target detection designed for use in military developmental test and evaluation settings. The model integrates research results from the fields of early vision, object recognition, and psychophysics. The VDM2000 is image based and provides a criterion-independent measure of target conspicuity, referred to as the vehicle metric (VM). A large data set of human responses to photographs of military vehicles in a field setting was used to validate the model. The VM adjusted by a single calibration parameter accounts for approximately 80% of the variance in the validation data. The primary application of this model is to predict detection of military targets in daylight with the unaided eye. The model also has application to target detection prediction using infrared night vision systems. The model has potential as a tool to evaluate the visual properties of more general task settings.
Computational Motor Control and Human Factors: Modeling Movements in Real and Possible Environments
Authors: Jax Steven A. , Rosenbaum David A. , Vaughan Jonathan , Meulenbroek Ruud G. J.
Published: March 2004

An aim of human factors research is to have models that allow for the advance design of user-friendly environments. This is still a distant dream because existing models are not yet sufficiently sophisticated. Models in the domain of motor control are a case in point, but recent developments in computational motor control suggest that the gap between the current state of modeling in this area and the desired state is shrinking. To illustrate this point, we review principles of motor control research that any model of motor control must accommodate. Then we describe a model that captures many of the capacities of actors in the everyday world, including the capacity to reach for objects in different ways depending on factors such as the ease with which different joints can rotate, the required speed of movement, and whether obstacles are present. The model relies on the ideas that goal postures are internally specified before movements are generated, that tasks are defined with flexibly ordered constraint hierarchies, and that movements can be shaped according to task demands. Actual or potential applications of this research include designing and testing possible environments where motor components play a key role.
Production Compilation: A Simple Mechanism to Model Complex Skill Acquisition
Authors: Taatgen Niels A. , Lee Frank J.
Published: March 2004

In this article we describe production compilation, a mechanism for modeling skill acquisition. Production compilation has been developed within the ACT-Rational (ACT-R; J. R. Anderson, D. Bothell, M. D. Byrne, & C. Lebiere, 2002) cognitive architecture and consists of combining and specializing task-independent procedures into task-specific procedures. The benefit of production compilation for researchers in human factors is that it enables them to test the strengths and weaknesses of their task analyses and user models by allowing them to model the learning trajectory from the main task level and the unit task level down to the keystroke level. We provide an example of this process by developing and describing a model learning a simulated air traffic controller task. Actual or potential applications of this research include the evaluation of user interfaces, the design of systems that support learning, and the building of user models.
Differences in Safety Climate between Hospital Personnel and Naval Aviators
Authors: Gaba David M. , Singer Sara J. , Sinaiko Anna D. , Bowen Jennie D. , Ciavarelli Anthony P.
Published: March 2004

We compared results of safety climate survey questions from health care respondents with those from naval aviation, a high-reliability organization. Separate surveys containing a subset of 23 similar questions were conducted among employees from 15 hospitals and from naval aviators from 226 squadrons. For each question a “problematic response” was defined that suggested an absence of a safety climate. Overall, the problematic response rate was 5.6% for naval aviators versus 17.5% for hospital personnel (p < .0001). The problematic response was 20.9% in highhazard hospital domains such as emergency departments and operating rooms. Problematic response among hospital workers was up to 12 times greater than that among aviators on certain questions. Although further research on safety climate in health care is warranted, hospitals may need to make substantial changes to achieve a safety climate consistent with the status of high-reliability organizations.
Associations between Errors and Contributing Factors in Aircraft Maintenance
Authors: Hobbs Alan , Williamson Ann
Published: March 2004

In recent years cognitive error models have provided insights into the unsafe acts that lead to many accidents in safety-critical environments. Most models of accident causation are based on the notion that human errors occur in the context of contributing factors. However, there is a lack of published information on possible links between specific errors and contributing factors. A total of 619 safety occurrences involving aircraft maintenance were reported using a self-completed questionnaire. Of these occurrences, 96% were related to the actions of maintenance personnel. The types of errors that were involved, and the contributing factors associated with those actions, were determined. Each type of error was associated with a particular set of contributing factors and with specific occurrence outcomes. Among the associations were links between memory lapses and fatigue and between rule violations and time pressure. Potential applications of this research include assisting with the design of accident prevention strategies, the estimation of human error probabilities, and the monitoring of organizational safety performance.
Designing Teams for First-of-a-Kind, Complex Systems Using the Initial Phases of Cognitive Work Analysis: Case Study
Authors: Naikar Neelam , Pearce Brett , Drumm Dominic , Sanderson Penelope M.
Published: March 2004

We present a technique for team design based on cognitive work analysis (CWA). We first develop a rationale for this technique by discussing the limitations of conventional approaches for team design in light of the special characteristics of first-of-a-kind, complex systems. We then introduce the CWA-based technique for team design and provide a case study of how we used this technique to design a team for a first-of-a-kind, complex military system during the early stages of its development. In addition to illustrating the CWA-based technique by example, the case study allows us to evaluate the technique. This case study demonstrates that the CWA-based technique for team design is both feasible and useful, although empirical validation of the technique is still necessary. Applications of this work include the design of teams for first-of-a-kind, complex systems in military, medical, and industrial domains.
Speed-of-Processing and Driving Simulator Training Result in Improved Driving Performance
Authors: Roenker Daniel L. , Cissell Gayla M. , Ball Karlene K. , Wadley Virginia G. , Edwards Jerri D.
Published: March 2004

Useful field of view, a measure of processing speed and spatial attention, can be improved with training. We evaluated the effects of this improvement on older adults' driving performance. Elderly adults participated in a speed-of-processing training program ( N = 48), a traditional driver training program performed in a driving simulator ( N = 22), or a low-risk reference group ( N = 25). Before training, immediately after training or an equivalent time delay, and after an 18-month delay each participant was evaluated in a driving simulator and completed a 14-mile (22.5-km) open-road driving evaluation. Speed-of-processing training, but not simulator training, improved a specific measure of useful field of view (UFOV®), transferred to some simulator measures, and resulted in fewer dangerous maneuvers during the driving evaluation. The simulator-trained group improved on two driving performance measures: turning into the correct lane and proper signal use. Similar effects were not observed in the speed-of-processing training or low-risk reference groups. The persistence of these effects over an 18-month test interval was also evaluated. Actual or potential applications of this research include driver assessment and/or training programs and cognitive intervention programs for older adults.
Effects of Age, Speech Rate, and Environmental Support in Using Telephone Voice Menu Systems
Authors: Sharit Joseph , Czaja Sara J. , Nair Sankaran , Lee Chin Chin
Published: March 2004

Age differences in the use of telephone menu systems were investigated in two experiments. Participants from three age groups (younger: 18--39; middle-aged: 40--59; older: 60+ years) were required to obtain specified information or perform some action using simulated voice menu systems. Measures reflecting task performance, menu navigation, and subjective responses were collected. The focus in Experiment 1 was on examining the effect of speech rate. Data from 196 participants indicated age differences in performance, especially for complex problems. There was no effect of speech rate on any of the performance measures. Experiment 2 examined two types of support devices: a screen phone and a graphical aid. Data from 114 participants indicated that the screen phone provided some benefits in navigational efficiency. In terms of performance, the older participants benefited more from the graphical aid and the younger participants performed better with the screen phone. Actual or potential applications of this research include guidance in the use of support devices that can reduce memory demands and the identification of appropriate speech rates.
Cognitive Demands of Collision Avoidance in Simulated Ship Control
Authors: Robert G. , Hockey J. , Healey Alex , Crawshaw Martin , Wastell David G. , Sauer Jürgen
Published: March 2004

The study examines the cognitive demands of collision avoidance under a range of maritime scenarios. Operators used a PC-based radar simulator to navigate set courses over 100 6-min trials varying in collision threat and traffic density. Corrective maneuvers were made through the application of standard navigation rules and by using two decision aids (target acquisition and test maneuver). Results showed widespread effects of collision threat in terms of decision aid use, subjective workload, and secondary task performance. Most notably, demand increased markedly over the course of emergency trials, in which collision threat resulted from rule violation by target vessels. The findings are discussed in terms of the comparison between predictable demands (requiring standard course changes) and those involving uncertainty about the others' intentions (involving more intensive monitoring and forced delays in corrective action). The study has relevance for the design of collision avoidance systems, specifically for the use of ecological displays.
Measuring the Fit between Human Judgments and Automated Alerting Algorithms: A Study of Collision Detection
Authors: Bisantz Ann M. , Pritchett Amy R.
Published: March 2004

Methodologies for assessing human judgment in complex domains are important for the design of both displays that inform judgment and automated systems that suggest judgments. This paper uses the n-system lens model to evaluate the impact of displays on human judgment and to explicitly assess the similarity between human judgments and a set of potential judgment algorithms for use in automated systems. First, the need for and concepts underlying judgment analysis are outlined. Then the n-system lens model and its parameters are formally described. This model is then used to examine a previously conducted study of aircraft collision detection that had been analyzed using standard analysis of variance methods. Our analysis found the same main effects as did the earlier analysis. However, n-system lens model analysis was able to provide greater insight into the information relied upon for judgments and the impact of displays on judgment. Additionally, the analysis was able to identify attributes of human judgments that were---and were not---similar to judgments produced by automated systems. Potential applications of this research include automated aid design and operator training.
Effects of Load and Speed on Lumbar Vertebral Kinematics during Lifting Motions
Authors: Zhang Xudong , Xiong Jinjun , Bishop Angela M.
Published: March 2004

This experimental study investigated the effects of load magnitude and movement speed on lumbar vertebral kinematics during lifting task performance. Ten participants performed sagittally symmetric lifting movements with systematically varied load using either a normal or a faster-than-normal speed. Skin-surface markers were strategically placed over the participants' spinous processes and other landmarks representing major body joints and were recorded during the movements by a motion capture system. The center of rotation (COR) locations and segmental movement profiles for lumbar vertebrae L2 to L5 were derived and analyzed. Results suggested that (a) the COR locations and vertebral angular displacement were not significantly affected by the speed or load variation; (b) a faster speed tended to shorten the time to complete the acceleration for all the lumbar vertebrae considered; and (c) the load increase incurred a tendency for the L5 to complete the primary displacement in a briefer time while enduring greater peak acceleration and velocity. The findings lead to a better understanding of the relation between lifting dynamics and spinal motion. Potential applications of this research include the development of more accurate biomechanical models and software tools for depicting spinal motions and quantifying low-back stress.