bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Water Quality Profiles from Shallow Monitoring Wells and Adjacent Multilevel Samplers
Authors: Metcalf Meredith J. , Robbins Gary A.
Published: February 2007

This study provides a comparison of water quality profiles taken within the screened interval of five shallow monitoring wells and those obtained from adjacent multilevel sampler clusters. Parameters compared are oxidation‐reduction potential, electrical conductivity, temperature, methylotertiary‐butyl ether (MTBE) concentrations, and chloride concentrations. The constituents were found to be relatively constant with depth within the monitoring wells, despite large variations observed with depth in the discrete samplers. Parameter homogenization in the wellbores can be explained by vertical flow conditions, as revealed by hydraulic head measurements in the multilevel samplers. The results suggest that sampling conventional shallow monitoring wells with active or passive samplers at different depths within a well screen will not provide an accurate indication of how constituents may vary in the adjacent formation with depth.
Regulation of KATP channel subunit gene expression by hyperglycemia in the mediobasal hypothalamus of female rats
Authors: Acosta-Martínez Maricedes , Levine Jon E.
Published: February 2007

The ATP-sensitive potassium (KATP) channels are gated by intracellular adenine nucleotides coupling cell metabolism to membrane potential. Channels comprised of Kir6.2 and SUR1 subunits function in subpopulations of mediobasal hypothalamic (MBH) neurons as an essential component of a glucose-sensing mechanism in these cells, wherein uptake and metabolism of glucose leads to increase in intracellular ATP/ADP, closure of the channels, and increase in neuronal excitability. However, it is unknown whether glucose and/or insulin may also regulate the gene expression of the channel subunits in the brain. The present study investigated whether regulation of KATP channel subunit gene expression might be a mechanism by which neuronal populations adapt to prolonged changes in glucose and/or insulin levels in the periphery. Ovariectomized, steroid-replaced rats were fitted with indwelling jugular catheters and infused for 48 h with saline, glucose (hyperglycemia-hyperinsulinemia), insulin and glucose (hyperinsulinemia), diazoxide (control), or glucose and diazoxide (hyperglycemia). At the end of infusions, the MBH, preoptic area, and pituitary were dissected for RNA isolation and RT-PCR. Hyperglycemia decreased Kir6.2 mRNA levels in the MBH in both the presence and absence of hyperinsulinemia. These same conditions also produced a trend toward decreased SUR1 mRNA levels in the MBH; however, it did not exceed statistical significance. Hyperglycemia increased whereas hyperinsulinemia reduced neuropeptide Y mRNA levels when these groups were compared with each other. However, neither was significantly different from values observed in saline-infused controls. In conclusion, hyperglycemia per se may alter expression of KATP channels and thereby induce changes in the excitability of some MBH neurons.
Imputation of Missing Ages in Pedigree Data
Authors: Balise Raymond R. , Chen Yu , Dite Gillian , Felberg Anna , Sun Limei , Ziogas Argyrios , Whittemore Alice S.
Published: February 2007

Background: In human pedigree data age at disease occurrence frequently is missing and is imputed using various methods. However, little is known about the performance of these methods when applied to families. In particular, there is little information about the level of agreement between imputed and actual values of temporal data and their effects on inferences. Methods: We performed two evaluations of five imputation methods used to generate complete data for repositories to be shared by many investigators. Two of the methods are mean substitution methods, two are regression methods and one is a multiple imputation method based on one of the regression methods. To evaluate the methods, we randomly deleted the years of disease diagnosis of some men in a sample of pedigrees ascertained as part of a prostate cancer study. In the first evaluation, we used the five methods to impute the missing diagnosis years and evaluated agreement between imputed and actual values. In the second evaluation, we compared agreement between regression coefficients estimated using imputed diagnosis years with those estimated using the actual years. Results/Conclusions: For both evaluations, we found optimal or near-optimal performance from a regression method that imputes a man’s diagnosis year based on the year of birth and year of last observation of all affected men with complete data. The multiple imputation analogue of this method also performed well.
In Vivo Shear Stress Determines Circulating Levels of Endothelial Microparticles in End-Stage Renal Disease
Authors: Boulanger Chantal M. , Amabile Nicolas , Guérin Alain P. , Pannier Bruno , Leroyer Aurélie S. , Mallat Ziad , Nguyen Clément , Tedgui Alain , London Gérard M.
Published: February 2007

Shear stress is a major determinant of endothelial apoptosis, but its role in the in vivo release of shed membrane microparticles by endothelial cells remains unknown. Thus, we sought to evaluate the possible relationship between circulating endothelial microparticle levels and laminar shear stress in end-stage renal disease patients with high cardiovascular risk, whose levels of endothelial microparticles are elevated. In 34 hemodialyzed patients, we analyzed the relationships between brachial artery and aortic shear stress and circulating microparticles levels. Only endothelial microparticles were inversely correlated with laminar shear stress values (
P
<0.0001) or its components shear rate and whole blood viscosity, independent of age or arterial blood pressure. Changes in hematocrit resulting from hemodialysis-induced hemoconcentration or erythropoietin anemia improvement induced a significant increase in whole blood viscosity and shear stress and were associated with a significant decrease in endothelial microparticles with a significant and inverse correlation with changes in hematocrit/hemoglobin or laminar shear stress. These results demonstrate that, in end-stage renal disease patients, laminar shear stress is an important determinant of plasma levels of endothelial microparticles. Anemia as an important determinant of whole blood viscosity and shear stress, contributes to endothelial apoptosis, and could play an indirect role in the pathogenesis of accelerated arteriosclerosis in this high-risk population.
The Influence of Time-Dependent Melting on the Dynamics and Precipitation Production in Maritime and Continental Storm Clouds
Authors: Phillips Vaughan T. J. , Pokrovsky Andrei , Khain Alexander
Published: February 2007

Simulations of one maritime and four continental observed cases of deep convection are performed with the Hebrew University Cloud Model that has spectral bin microphysics. The maritime case is from observations made on 18 September 1974 during the Global Atmospheric Research Program’s Atlantic Tropical Experiment (GATE). The continental storm cases are those of summertime Texas clouds observed on 13 August 1999, and green-ocean, smoky, and pyro-clouds observed during the Large-Scale Biosphere–Atmosphere Experiment in Amazonia–Smoke, Aerosols, Clouds, Rainfall, and Climate (LBA–SMOCC) campaign on 1–4 October 2002. Simulations have been performed for these cases with a detailed melting scheme. This scheme allows calculation of liquid water fraction within each mass bin for the melting of graupel, hail, snowflakes, and crystals, as well as alteration of the sedimentation velocity of ice particles in the course of their melting. The results obtained with the detailed melting scheme are compared with corresponding results from simulations involving instantaneous melting at the freezing (0°C) level.

The detailed melting scheme allows penetration of ice from the freezing level down into the boundary layer by distances ranging from a few hundred meters for the numerous, smaller particles to ∼1.5 km for the largest particles, which are much scarcer. In these simulations, most of the mass of ice falling out melts over this short distance of a few hundred meters. The deepening and intensification of the layer of latent cooling enhances the convective destabilization of the troposphere. This effect is especially pronounced under continental conditions, causing significant changes in the accumulated rain amount.
Dependence of Simulation of Boreal Summer Tropical Intraseasonal Oscillations on the Simulation of Seasonal Mean
Authors: Ajayamohan R. S. , Goswami B. N.
Published: February 2007

The link between realism in simulation of the seasonal mean precipitation and summer tropical intraseasonal oscillations and their dependence on cumulus parameterization schemes is investigated using the Florida State University Global Spectral Model (FSUGSM). Forty-member model ensemble simulations of the northern summer season are generated for three different cumulus parameterization schemes [namely, Arakawa–Schubert (Naval Research Laboratory; NRL), Zhang and McFarlane (National Center for Atmospheric Research; NCAR), and Emanuel (Massachusetts Institute of Technology; MIT)]. The MIT scheme simulates the regional pattern of seasonal mean precipitation over the Indian monsoon region well but has large systematic bias in simulating the precipitation over the western Pacific and the Maritime Continent. Although the simulation of details of regional distribution of precipitation over the Indian monsoon region by the NRL and NCAR schemes is not accurate, they simulate the spatial pattern of precipitation over the tropical Indo–Pacific domain closer to observation. The NRL scheme seems to captures the observed northward and eastward propagation of intraseasonal precipitation anomalies realistically. However, the simulations of the NCAR and MIT schemes are dominated by a westward propagating component. The westward propagating mode seen in the model as well as observations is indicated to be an equatorial Rossby wave modified by the northern summer mean flow. An examination of the relationship between simulation of the model climatology and eastward propagating character of monsoon intraseasonal oscillations (ISOs) in a limited sample shows that the scheme that simulates better seasonal mean pattern of rainfall over the tropical Indo–Pacific domain also simulates better intraseasonal variance and more realistic eastward propagation of monsoon ISOs. Among the parameters known to be important for meridional propagation of the summer monsoon ISOs, the meridional gradient of mean humidity in the lower atmosphere seems to be crucial in determining the northward propagation in the equatorial Indian Ocean (between 10°S and 10°N). For better prediction of the seasonal mean Indian monsoon, therefore, the model climatology should have minimum bias not only over the Indian monsoon region but also over the entire Indo–Pacific basin.
Mechanisms of the Great Plains Low-Level Jet as Simulated in an AGCM
Authors: Jiang Xianan , Lau Ngar-Cheung , Held Isaac M. , Ploshay Jeffrey J.
Published: February 2007

A model diagnosis has been performed on the nocturnal Great Plains low-level jet (LLJ), which is one of the key elements of the warm season regional climate over North America. The horizontal–vertical structure, diurnal phase, and amplitude of the LLJ are well simulated by an atmospheric general circulation model (AGCM), thus justifying a reevaluation of the physical mechanisms for the formation of the LLJ based on output from this model. A diagnosis of the AGCM data confirms that two planetary boundary layer (PBL) processes, the diurnal oscillation of the pressure gradient force and of vertical diffusion, are of comparable importance in regulating the inertial oscillation of the winds, which leads to the occurrence of maximum LLJ strength during nighttime. These two processes are highlighted in the theories for the LLJ proposed by Holton (1967) and Blackadar (1957). A simple model is constructed in order to study the relative roles of these two mechanisms. This model incorporates the diurnal variation of the pressure gradient force and vertical diffusion coefficients as obtained from the AGCM simulation. The results reveal that the observed diurnal phase and amplitude of the LLJ can be attributed to the combination of these two mechanisms. The LLJ generated by either Holton’s or Blackadar’s mechanism alone is characterized by an unrealistic meridional phase shift and weaker amplitude.

It is also shown that the diurnal phase of the LLJ exhibits vertical variations in the PBL, more clearly at higher latitudes, with the upper PBL wind attaining a southerly peak several hours earlier than the lower PBL. The simple model demonstrates that this phase tilt is due mainly to sequential triggering of the inertial oscillation from upper to lower PBL when surface cooling commences after sunset. At lower latitudes, due to the change of orientation of prevailing mean wind vectors and the longer inertial period, the inertial oscillation in the lower PBL tends to be interrupted by strong vertical mixing in the following day, whereas in the upper PBL, the inertial oscillation can proceed in a low-friction environment for a relatively longer duration. Thus, the vertical phase tilt initiated at sunset is less evident at lower latitudes.
Waves in a Cloudy Vortex
Authors: Schecter David A. , Montgomery Michael T.
Published: February 2007

This paper derives a system of equations that approximately govern small-amplitude perturbations in a nonprecipitating cloudy vortex. The cloud coverage can be partial or complete. The model is used to examine moist vortex Rossby wave dynamics analytically and computationally. One example shows that clouds can slow the growth of phase-locked counter-propagating vortex Rossby waves in the eyewall of a hurricane-like vortex. Another example shows that clouds can (indirectly) damp discrete vortex Rossby waves that would otherwise grow and excite spiral inertia–gravity wave radiation from a monotonic cyclone at high Rossby number.
A Study of the Energetics of African Easterly Waves Using a Regional Climate Model
Authors: Hsieh Jen-Shan , Cook Kerry H.
Published: February 2007

The evolution and spatial distribution of the energetics of African waves are studied. Complete eddy energy equations for an open system are derived for the computation of energy transformations during wave generation and dissipation. It is found that baroclinic overturning is the dominant energy source, although barotropic conversions can be almost equally important when there is concentrated moist convection south of the jet or shallow cumulus convection beneath the jet. The generation of active waves usually results from the nearly in-phase evolution of baroclinic and barotropic conversions, which are associated with significant rainfall over Africa.

Significant barotropic instability associated with the horizontal shear is usually induced by concentrated deep convection on the southern flank of the jet. Barotropic conversions associated with the vertical wind shear may attain even greater magnitudes than that associated with the horizontal shear when shallow cumulus convection beneath the jet is strong. The eddy available potential energy consumed by the baroclinic overturning is compensated directly by the conversion of zonal to eddy available potential energy and the generation of eddy potential energy by diabatic heating. These direct conversions of latent heat and zonal available potential energy suggest that interactions across space scales, from convective space scales to the large scales, are important for generating African waves. The convectively induced barotropic instability may enhance baroclinic overturning through the resonance between these two instabilities. This leads to the nonlinear interaction of the waves with convection, corresponding to the formation of organized precipitation migrating with the waves.

A space–time spectral analysis shows that the dispersion characteristics of African easterly waves with wavelengths between 2650 and 4000 km do not follow the dispersion relation of the shallow water waves, indicating that these waves, similar to other easterly waves in the Tropics, possess significant nonlinearity, and cannot be fully explained by linear wave theory.
Simulated Convective Lines with Parallel Stratiform Precipitation. Part I: An Archetype for Convection in Along-Line Shear
Authors: Parker Matthew D.
Published: February 2007

This article, the first of two describing convective lines with parallel stratiform (PS) precipitation, addresses the basic kinematic and precipitation features of these systems. The PS mode appears to be the preferred organizational structure in environments with line-parallel vertical wind shear. This archetype for long-lived convective systems has received relatively little attention to date, and yet it is frequently implicated in flash flooding because it entails both the along-line movement of hydrometeors and back-building convective development. As a reality check, this paper presents conventional observations of the wind and reflectivity fields associated with an archetypal PS system from 2 May 1997. Thereafter, analyses of idealized numerical simulations serve as the basis for a more detailed investigation of PS systems’ internal structures and processes.

The observations and simulations suggest several unique aspects of the PS structure. The environment’s vertically sheared 3D wind profile helps to explain PS systems’ tendency to back-build, develop line-parallel precipitation, and evolve asymmetrically. Along-line flow within the system cold pool entails back-building on both the mesoscale and the convective scale. As well, along-line flow in the upper troposphere within the system entails along-line hydrometeor transports, especially in the leading and trailing anvils. These behaviors lead to the archetypal PS structure.

Along-line hydrometeor advection means that much of the system’s precipitation falls very near its outflow boundary, and that the convective cells can seed other updrafts farther down the line. As a result, PS systems in line-parallel shear can intensify their cold pools quite rapidly. As well, in time the PS structure is characterized by diminished upper-tropospheric along-line flow within its axis. These factors may hasten transition toward a predominantly rearward-sloped updraft and the production of trailing precipitation. Even in the absence of Coriolis accelerations, this evolutionary pathway leads to highly asymmetric structures, such as are commonly observed in midlatitudes.

The present introductory exposition of PS systems in deep tropospheric line-parallel wind shear sets the stage for a detailed investigation of their dynamics and sensitivities in a companion article.
Simulated Convective Lines with Parallel Stratiform Precipitation. Part II: Governing Dynamics and Associated Sensitivities
Authors: Parker Matthew D.
Published: February 2007

This article is the second of two describing convective lines with parallel stratiform (PS) precipitation. The PS mode appears to be the preferred organizational structure in environments with line-parallel vertical wind shear. This paper presents a detailed analysis of the processes that lead to the development of the PS structure within line-parallel shear, and the positive and negative feedbacks associated with the mature PS structure. As well, the particular importance of line-perpendicular and line-parallel wind shear, line-end effects, inertial stability, and patterns of convective initiation are investigated through a battery of sensitivity tests.

Convective lines with PS precipitation develop in environments with both significant line-perpendicular and line-parallel vertical wind shear. Although the studied environments are initially supportive of supercells, the merging of outflows soon renders a predominant linear forcing and the characteristic PS structure. The systems’ linearity in the presence of along-line wind shear makes the local wind field more dependent upon the mesoscale structure of the convective system. For example, the along-line transport of hydrometeors is required for the development of a line-parallel precipitation region, and yet this transport does not occur immediately down the convective line’s axis because it is interrupted by the pressure maxima associated with other convective cells that are farther down the line. However, the along-line flow within the line’s leading and trailing anvils is able to contribute substantially because there are along-line pressure gradient accelerations associated with the tilted mesoscale structure of the system’s buoyancy field.

This paper concludes the study by synthesizing its dynamical and sensitivity analyses with the overarching structures described in the companion article, yielding perhaps the first consolidated view of these little-studied systems.
Dynamics of the Southern Hemisphere Spiral Jet
Authors: Williams Lindsey N. , Lee Sukyoung , Son Seok-Woo
Published: February 2007

The formation of the Southern Hemisphere spiral jet is investigated using observations over a 40-yr period. It is found that between late March and early April, the upper-tropospheric westerly jet in the Southern Hemisphere undergoes a transition from an annular structure in midlatitudes to a spiral structure that extends from 20° to 55°S. The transition to the spiral structure is initiated by the formation of a subtropical jet, localized in the central Pacific. The inception of the jet spiral is completed with the formation of a band of northwest-to-southeast-oriented zonal winds, which is connected to both the subtropical and the polar-front jets. This band, referred to as the tilting branch, arises from momentum flux convergence associated with breaking Rossby waves. As such, the direction of the wave breaking determines the direction of the jet spiral; an anticyclonic wave breaking, associated with equatorward wave dispersion, establishes a jet spiral that turns cyclonically toward the pole.

This formation mechanism of the jet spiral is supported by a set of calculations with an idealized numerical model. These model calculations indicate that the jet spiral is obtained only if the model’s localized subtropical jet is sufficiently strong, and if the latitude of the polar-front jet is sufficiently higher than that of the subtropical jet. The calculations also indicate that the spiral jet is a transient solution, implying that the lack of spiral structure during the austral winter may be caused by the zonal wind field reaching a new statistically steady state.
Metadata from WMO Publication No. 47 and an Assessment of Voluntary Observing Ship Observation Heights in ICOADS
Authors: Kent Elizabeth C. , Woodruff Scott D. , Berry David I.
Published: February 2007

It is increasingly recognized that metadata can significantly improve the quality of scientific analyses and that the availability of metadata is particularly important for the study of climate variability. The International Comprehensive Ocean–Atmosphere Data Set (ICOADS) contains in situ observations frequently used in climate studies, and this paper describes the ship metadata that are available to complement ICOADS. This paper highlights the metadata available in World Meteorological Organization Publication No. 47 that include information on measurement methods and observation heights. Changing measurement methods and heights are known to be a cause of spurious change in the climate record. Here the authors focus on identifying measurement heights for air temperature and wind speed and also give information on SST measurement depths.
An Improved QC Process for Temperature in the Daily Cooperative Weather Observations
Authors: Hubbard Kenneth G. , Guttman Nathaniel B. , You Jinsheng , Chen Zhirong
Published: February 2007

TempVal is a spatial component of data quality assurance algorithms applied by the National Climatic Data Center (NCDC), and it has been used operationally for about 4 yr. A spatial regression test (SRT) approach was developed at the regional climate centers for climate data quality assurance and was found to be superior to currently used quality control (QC) procedures for the daily maximum and minimum air temperature. The performance of the spatial quality assessment procedures has been evaluated by assessing the rate with which seeded errors are identified. A complete dataset with seeded errors for the year 2003 for the contiguous United States was examined for both the maximum and minimum air temperature. The spatial regression quality assessment component (SRT), originating in the Automated Climate Information System (ACIS), and TempVal, originating in the NCDC database, were applied separately and evaluated through the ratio of identified seeded errors to the total number of seeds. The spatial regression test applied in the ACIS system was found to perform better in identifying the seeded errors. For all months, the relative frequency of correct identification of wrong data is 0.72 and 0.83 for TempVal and SRT, respectively. The goal of the comparison was to evaluate quality assurance techniques that could improve data quality assessment at the NCDC, and the results of the comparison led to the recommendation that the SRT be included in the NCDC quality assessment methodology.
High-Resolution Measurement of Size Distributions of Asian Dust Using a Coulter Multisizer
Authors: Kobayashi Hiroshi , Arao Kimio , Murayama Toshiyuki , Iokibe Kengo , Koga Ryuji , Shiobara Masataka
Published: February 2007

A Coulter Multisizer, which is based on the electrical sensing zone (ESZ) or the Coulter principle, was used to measure the size distribution of Asian dust. Coulter Multisizer analysis provides high-resolution size measurements of water-insoluble aerosol particles (WIPs) and the number concentration at each size bin. Aerosol filter sampling was conducted at four sites in Japan during spring 2003. The measured volume size distributions fit fairly well with a lognormal distribution. The results show that the WIP size distributions of the same Asian dust air mass varied at each sampling site and the volume mode diameter at the sites reduced from west to east. The derived volume mode diameter ranged from 1.4 to 2.2 μm and was comparatively smaller than those in previous studies on Asian dust. This can be explained by the possible internal mixing of Asian dust with other components and by the breaking of particles and dispersion of aggregations by ultrasonification during extraction. The analysis method was improved by washing the aerosol particles collected on a filter using a magnetic stirrer, instead of an ultrasonic cleaner. As a result, the WIP size distribution can be measured in the range of 1–10 μm. The measured mode diameters were 2.6–3.1 and 4.3–5.6 μm in 2 Asian dust phenomena at Kofu, Japan, in 2004. It is demonstrated that the Coulter Multisizer method can furnish detailed information regarding the spatial and temporal variations in the mineral dust size distribution.
Estimation of Water Temperature of Large Lakes in Cold Climate Regions during the Period of Strong Coupling between Water and Air Temperature Fluctuations
Authors: Bussières Normand , Granger Raoul J.
Published: February 2007

Near-surface bulk water temperature measured in large northern lakes during the warm season with buoys can be characterized by three components: a slowly varying seasonal-/climate-related trend, fluctuations at the time scale of weather perturbations, and rapid daily fluctuations. When thermal infrared data are used to estimate surface water temperature, an additional term relating the differences between the skin and bulk temperatures is implied. Buoy data in this work serve to demonstrate the existence of a period of strong signal coupling between fluctuations of water temperature and air temperature. The period of strong signal coupling does not extend beyond the date of maximum temperature in the water temperature trend. During this period, a simple linear transformation of air temperature fluctuations can be used to simulate the buoy water temperature fluctuations. Attempts to simulate water temperature fluctuations from air temperature alone are not possible beyond this period. Water temperature simulation error depends on the distance of the air temperature measurement from the buoy, ranging from ±1.1°C at 0 km to ±1.4°C at 40 km. The method developed with buoy data is applied to the combination of satellite thermal infrared and operationally measured air temperature data to simulate water temperatures. Through the use of satellite data, the water temperature simulations are extended beyond the period of strong coupling.
Acceleration and Time Pathologies
Authors: Aho Kevin A.
Published: February 2007

In his Contributions to Philosophy, Martin Heidegger (1999) introduces ‘acceleration’ as one of the three symptoms – along with ‘calculation’ and the ‘outbreak of massiveness’ – of our technological way of ‘being-in-the-world’. In this article, I unpack the relationship between these symptoms and draw a twofold conclusion. First, interpreting acceleration in terms of time pathologies, I suggest the self is becoming increasingly fragmented and emotionally overwhelmed from chronic sensory arousal and time pressure. This experience makes it difficult for us to qualitatively distinguish what matters to us in our everyday lives, resulting in a pervasive cultural mood of indifference, what Heidegger (1995) calls ‘profound boredom’. Second, by drawing on Heidegger's hermeneutic method, I argue that the practice of mainstream psychology, by adopting the reductive methodology of the empirical sciences, largely ignores our accelerated socio-historical situation, resulting in therapeutic models that have a tendency to construct and perpetuate the very pathologies the psychologist is seeking to treat.
Timescapes of Flexibility and Insecurity
Authors: Raddon Arwen
Published: February 2007

This article draws on the concept of ‘timescape’ (Adam, 1998) to explore the context of distance learners' stories about their reasons for studying. It examines these learners' narratives of being located in a socio-historical time and space in which there is a greater need for flexibility in relation to the times and spaces of work and how this is underpinned by a strong sense of insecurity of work. Engaging in continued learning becomes one means of coping with this timescape, by becoming more flexible and remaining employable. In exploring these micro-level narratives, this article highlights both some of the multiple, interlinked layers of time and space, the impact of macro-level discourses of flexibility, insecurity and lifelong learning, and the gendered and other power relations around these. It also reflects on the theoretical and empirical use of the concept of the timescape, arguing that the narrative or biographical approach provides a useful means through which to explore the timescapes of individuals and groups.
‘How Many Hours Do You Usually Work?’
Authors: Tijdens Kea , Dragstra Anna
Published: February 2007

This article reviews how working hours are asked for in 26 large-scale surveys in six countries plus the European Union. Four dimensions of working time were investigated, notably number of working hours, timing of work, predictability and control over hours, and commuting time. Although almost all questionnaires ask for hours worked, the terminology varies greatly. In only half of the cases a reference period is taken into account and in half the reasons for working more/less in the survey week than usual are asked for. Contractual hours are hardly asked for and so are paid and unpaid overtime hours. The timing of work is asked for in a minority of the questionnaires, and predictability and control over working hours is also not a major issue. The incidence of an on-call contract is the most likely proxy for predictability.
From Post to Pillar
Authors: Sissons Jeffrey
Published: February 2007

The establishment of Christianity in Rarotonga, Cook Islands, was as much a material process of indigenization as it was a local appropriation of foreign ideas. In this article I argue that the introduction of Christianity to Rarotonga in the 1820s entailed the creation of two competing social fields, one materialized through churches and the other materialized through marae (ceremonial enclosures with god-houses in which were stored wrapped wooden poles, representing divine ancestors). The argument for regarding churches and marae as materializations of social relations is developed against Gell's analysis, in Art and Agency, of Maori meeting houses in which he proposes that we approach such structures as indexes of agency.
The Story of the Amulet
Authors: Hill Jude
Published: February 2007

This article traces the stories of a group of amulets and charms from the early 20th century that were gathered together from different locations in Britain by the folklorist Edward Lovett. Through the sale of these objects, Lovett fostered a close working relationship with staff at the Wellcome Historical Medical Museum. In the museum, the amulets and charms were displayed as ‘scientific’ specimens as part of an attempt to trace the ‘history of medicine and mankind’. However, drawing on recent work reappraising the relationships between magic, authority and modernity, and, by recognizing the magical qualities of the objects involved, it is argued that these objects retained the potential to enchant, haunting the space of the museum and disrupting the narratives of evolution and progress presented in this context. A study of the amulets' lives beyond the locus of the museum also sheds light on the potential agency of such objects and the spatialities of magical materialities in an era of modernity.
Patterns and rates of intron divergence between humans and chimpanzees
Authors: Gazave Elodie , Marqués-Bonet Tomàs , Fernando Olga , Charlesworth Brian , Navarro Arcadi
Published: February 2007

Background

Introns, which constitute the largest fraction of eukaryotic genes and which had been considered to be neutral sequences, are increasingly acknowledged as having important functions. Several studies have investigated levels of evolutionary constraint along introns and across classes of introns of different length and location within genes. However, thus far these studies have yielded contradictory results.

Results

We present the first analysis of human-chimpanzee intron divergence, in which differences in the number of substitutions per intronic site (Ki) can be interpreted as the footprint of different intensities and directions of the pressures of natural selection. Our main findings are as follows: there was a strong positive correlation between intron length and divergence; there was a strong negative correlation between intron length and GC content; and divergence rates vary along introns and depending on their ordinal position within genes (for instance, first introns are more GC rich, longer and more divergent, and divergence is lower at the 3' and 5' ends of all types of introns).

Conclusion

We show that the higher divergence of first introns is related to their larger size. Also, the lower divergence of short introns suggests that they may harbor a relatively greater proportion of regulatory elements than long introns. Moreover, our results are consistent with the presence of functionally relevant sequences near the 5' and 3' ends of introns. Finally, our findings suggest that other parts of introns may also be under selective constraints.
Embodiment Awareness, Mathematics Discourse, and the Blind
Authors: QUEK FRANCIS , MCNEILL DAVID
Published: February 2007

Abstract: Blindness might be described as a biological condition, and thus remedies could be in the realm of biotechnology. However, the convergence of information technology and cognitive science offers great opportunities for understanding and helping blind children as they learn mathematics, the crosscutting discipline most important for all branches of science and engineering. This article outlines our logic and approach for providing blind students with awareness of the embodiment of their teachers to maintain situated communication. First, we shall show that math discourse is inherently spatiotemporal, and that this information is carried by gesticulation in conjunction with speech. Second, we shall explore the capacity of those who are blind for the imagism necessary for mathematics reasoning. Third, we shall advance a set of augmentative devices suggested by our analysis. Finally, we shall outline our ongoing experiments to validate our rationale.
Computer Animation of Gait
Authors: Broome D. R.
Published: February 2007

A program has been written which enables two dimensional visualization of leg movements on a computer graphics display. Hip, knee, ankle angle, and pelvic displacement information can be input and processed to obtain Fourier coefficients characterizing these motions. The thigh, shank and foot are then displayed at, for example, two hundred points within each walking cycle, at natural speed or as slowly as desired.
Meeting Reports-USA—Orthopaedic Research Society
Authors: Walker P. S.
Published: February 2007

Copies of the transactions can be obtained from M. G. Ehrlich, MD, Massachusetts General Hospital, Boston, Massachusetts 02114, USA: for the enclosed sum of †12.00 (including domestic or overseas mailing).
Forces in the Knee Joint Whilst Rising from Normal and Motorized Chairs
Authors: Ellis M I , Seedhom B B , Amis A A , Dowson D , Wright V
Published: February 2007

Knee joint forces were determined by kinesiological techniques using a high speed camera and force platforms so that a comparison could be made for rising from a normal chair without the aid of arms and with the aid of a motorized chair. For rising from a normal chair, the knee joint forces parallel to the long axis of the tibia at the point of contact between the tibia and femur, were found to be up to seven times body weight at about the time when the body left contact with the chair. Using a motorized chair the knee joint forces were reduced to less than body weight until normal standing was achieved.
UCL Hydraulic Arm Dynamics
Authors: Broome D R
Published: February 2007

The UCL arm prosthesis is briefly described and its general performance capabilities outlined. Evaluation tests were conducted to assess the dynamic response of the hydraulic servo actuator systems. These included measurements of saturation velocity and stall load of the main arm articulations. Detailed observations were made of the shoulder elevation function, the heaviest loaded actuator, to provide data on the transient response of this servosystem. An analysis is described of a general hydraulic actuator used as an angular position controller, and this is simplified and used as the basis of a digital simulation of the shoulder motion. Results of running the digital simulation show a very good correlation with the experimentally derived data. The paper concludes by re-emphasizing the considerable advantages to be gained by using hydraulic actuation, illustrated by these test results.
Mechanical Implications of Crimping in Collagen Fibres of Human Spinal Ligaments
Authors: Shah J S , Jayson M I V , Hampson W G J
Published: February 2007

The crimp morphology of collagen fibres from human cadaveric anterior longitudinal, posterior longitudinal and interspinous ligaments was demonstrated by the analysis of extinction and transmission bands seen across the axis of the fibres on transmission polarization microscopy. The experimentally observed force/strain behaviour of the fibres at low tensile forces was correlated quantitatively with their crimp structure. The initial extension of the fibres in the toe region of the stress-strain curve can be attributed to the deformity of crimps. Further confirmation of the crimp morphology, notably in rat tail tendons, by scanning electron microscopy, X-ray diffraction and transmission electron microscopy is discussed. Finally, it is suggested the crimp structure does alter in diseases and ageing. This may account for associated changes in the mechanical behaviour of the tissues.
The Effect of Fatigue in Polyurethane Foam Cushions on Patients Confined to Wheelchairs
Authors: Denne W A
Published: February 2007

A classic example of fatigue in polyurethane foam was recently provided by the failure of a cushion designed to relieve pressure from a decubitus sore. Comparative measurements on old and new cushions confirmed the lack of pressure relief in the fatigued sample and a mechanical investigation of foam properties provided an explanation of the mechanism. Further work indicated that polyurethane foam properties can be stabilized if the material is crushed a number of times prior to use. This can be done straightforwardedly between parallel rollers or even a mangle.
The Fracture of Femoral Components — An Act of God?
Authors: Dobbs H S
Published: February 2007

In previous work a probability model for the fracture of femoral components was presented. This model was based on the assumption that the components were defect-free and that they fractured by a process involving metal fatigue. The model predicted the probability of fracture as a function of the patient's body weight and as a function of the time elapsed since operation (Dobbs, 1977).

The present work is an extension of the model taking into account the patient's age and decreasing activity. It predicts the time dependence of the incidence of fracture and of the conditional failure rate. These predictions are compared with recently published survey data tending to support the view that the fracture of these components is a wearing-out process.
A Miniature Swashplate Water Pump for Powered Prostheses
Authors: McIntyre A W , Needham G A , McLeish R D
Published: February 2007

A miniature swashplate pump is described with a unique performance, as far as the authors are aware, delivering 1.5 ml/s of water at a pressure of 34 bar; the complete motor, gearbox and pump assembly weighing 315 gm and measuring 42 mm diameter by 108 mm long. An efficiency, electrical to fluid, of 61 per cent has been achieved under normal operating conditions, the pump mechanical efficiency being 78 per cent.

A synopsis of the pump development is included with details of the current design. Although this pump has been designed specifically for use in a hydraulically powered artificial arm system, with suitable modification it could be used in any application requiring a high pressure, low flow rate fluid delivery.
Forces in Animal Joints
Authors: Alexander R McN
Published: February 2007

Estimates have been made of the forces which act in major joints of various arthropods and vertebrates, in strenuous activities. Over the range of size from fleas to dinosaurs, joint forces tend to be roughly proportional to (body mass)-1/3. The maximum stresses which occur in joints are probably of the same order of magnitude in mammals of all sizes and also in insects of all sizes, but the stresses in insects are probably larger than the stresses in mammals and other vertebrates.
Carbon Fibre Reinforced Plastics for Load-Bearing Implants
Authors: Bradley J S , Hastings G W
Published: February 2007

Work is currently in progress concerning two distinct groups of carbon fibre composites for orthopaedic implants. This paper will emphasize the work on carbon fibre reinforced ultra high molecular weight polyethylene for which preliminary results have been reported (Bradley and Evans, 1977). Carbon fibre reinforced epoxy will be referred to only briefly owing to publication elsewhere (Bradley et al, 1980).
A Comparative Study of Healing of Osteotomized Rabbit Tibiae Using Different Methods of Closure of the Experimental Fracture Gap
Authors: Dwyer N St J P , Just D J
Published: February 2007

The paper describes the experimental results obtained from a series of mechanical tests on osteotomized rabbit tibiae that have been left to heal for a fixed period of time and which have been treated by different methods of internal fixation. Conclusions are drawn from the test results which are presented graphically.
An Interpretation of the Initial Low Stiffness Phase of the in Vivo Load Extension Relationship for Human Skin
Authors: Stark H L
Published: February 2007

Human skin has a highly non-linear load/extension relationship. The initial low stiffness phase is extremely variable with both site and orientation and is essentially the limit of physiologically viable uni-axial extension. A better understanding of the mechanics of this initial phase is sought, in particular the role of lateral contraction, in order that a more rational basis of modelling, the surgically more typical multi-axial strain condition, might be achieved. It is concluded that lateral contraction is not a corequisite of the initial low stiffness extension, and that fibre straightening is the more plausible explanation of this initial low stiffness phase, and its accompanying observed fibre reorientation.
Design Criteria for the Measurement of Pressure at Body/Support Interfaces
Authors: Ferguson-Pell M W
Published: February 2007

The design characteristics of pressure transducers for use at interfaces between the body and support surfaces such as mattresses, cushions, prosthetic sockets, and beneath bandages are discussed, and criteria for determining the maximum diameter and thickness of suitable devices are developed analytically. Sources of measurement error including transducer response to interface curvature, off-axis stresses, environmental factors and hysteresis are identified. The need for a calibration technique compatible with the mechanical conditions under which measurements are made is emphasized.
Some Evidence of Squeeze-Film Lubrication in Hip Prostheses
Authors: Gore T A , Higginson G R , Kornberg R E
Published: February 2007

A simple hip joint testing machine, standing between the simple pendulum and the joint simulator, is described. It is used to provide further evidence of the contribution of the squeeze-film mechanism to hip prosthesis lubrication when a viscous fluid is present.
A Robotic Arm and Worktable System for the Assistance of the Physically Handicapped
Authors: Semple E C
Published: February 2007

A teachable robotic arm is described which is capable of assisting the physically handicapped with eating, page-turning, drawing, etc. Particular features of the device are its relative simplicity, the scope for interaction with the machine which is available to the user, and the specially designed keyboard for control which can accommodate a variety of handicaps. User reaction to the device is discussed, and the technical and social difficulties which have arisen are brought out — the social problems being the more severe. Future related research to help handicapped people into the workforce is outlined.
A Biomechanical Analysis of the Functions of the Deltoid during Abduction of the Arm
Authors: Scholten P J M , de Boer A , Vuisting W
Published: February 2007

In this paper a method is presented for the analysis of the functions of the deltoid during abduction of the arm. The influence of several parameters such as the active and passive properties of the muscle, the length of the muscle fibres at certain positions of the arm, the kind of attachment of the deltoid to the scapula and the clavicula and the rotation of the scapula are discussed with respect to the behaviour of the muscle. The importance of the centre of rotation of the humerus in relation to the required equilibrium is shown.
Computer Graphics Illustration of the Operation of the Intervertebral Disc
Authors: Klein J A , Hickey D S , Hukins D W L
Published: February 2007

The annulus fibrosus, the outer wall of the intervertebral disc, has a lamellar structure. Each lamella is reinforced by collagen fibres. A theory has been developed which allows the response of the fibre network to disc deformation to be calculated. The theory has been formulated in a form suitable for computer graphics display of its predictions. Results enable the effects of compression, torsion, flexion and shear of the disc to be readily appreciated.