bluuebunny/crossref_metadata_2025 huggingface dataset:
Indirect Impact of Atmospheric Aerosols in Idealized Simulations of Convective–Radiative Quasi Equilibrium
Authors: Grabowski Wojciech W.
Published: September 2006

This paper discusses a cloud-resolving modeling study concerning the impact of warm-rain microphysics on convective–radiative quasi equilibrium with fixed surface characteristics and prescribed solar input, both mimicking the mean conditions on earth. Two limits of the concentration of cloud droplets, either 100 cm−3 (referred to as “pristine”) or 1000 cm−3 (referred to as “polluted”), are considered. In addition, three formulations of the effective radius of water droplets in diluted cloudy volumes are used, corresponding to the homogeneous, intermediate, and extremely inhomogeneous mixing scenarios. The assumed concentration of cloud droplets, together with the assumed mixing scenario, affects the local value of the effective radius of cloud droplets (the first indirect aerosol effect, also known as the Twomey effect) and the transfer of cloud water into drizzle and rain, which can affect the mean cloudiness and the hydrologic cycle (the second indirect effect).

The convective–radiative quasi equilibrium mimics the estimates of globally and annually averaged water and energy fluxes across the earth’s atmosphere to within less than 10 W m−2. As on earth, the model cloudiness is dominated by shallow convection. It is found that the impact of warm microphysics is dominated by the first indirect effect, whereas the second indirect effect has a smaller impact. The assumed droplet concentration and mixing scenario impact the mean “planetary” albedo and, thus, the amount of solar energy reaching the surface, with all other components of atmospheric energy and water budgets virtually the same in all simulations. The weak second indirect effect highlights the difference between the impact of cloud microphysics on a single cloud and the impact on an ensemble of clouds, with only the latter including the feedbacks between clouds and their environment. The formulation of the effective radius in the diluted cloudy volumes turns out to be of critical importance, with the amount of solar energy reaching the surface being the same in the pristine case assuming the homogeneous mixing scenario and in the polluted case with the extremely inhomogeneous mixing. This result emphasizes the essential role of poorly understood microphysical transformations within diluted convective clouds, which strongly impact the magnitude of the first indirect (Twomey) effect. Implications for future research in this area are discussed.
Optimal Forcing Patterns for Coupled Models of ENSO
Authors: Moore Andrew M. , Zavala-Garay Javier , Tang Youmin , Kleeman Richard , Weaver Anthony T. , Vialard Jérôme , Sahami Kamran , Anderson David L. T. , Fisher Michael
Published: September 2006

The optimal forcing patterns for El Niño–Southern Oscillation (ENSO) are examined for a hierarchy of hybrid coupled models using generalized stability theory. Specifically two cases are considered: one where the forcing is stochastic in time, and one where the forcing is time independent. The optimal forcing patterns in these two cases are described by the stochastic optimals and forcing singular vectors, respectively. The spectrum of stochastic optimals for each model was found to be dominated by a single pattern. In addition, the dominant stochastic optimal structure is remarkably similar to the forcing singular vector, and to the dominant singular vectors computed in a previous related study using a subset of the same models. This suggests that irrespective of whether the forcing is in the form of an impulse, is time invariant, or is stochastic in nature, the optimal excitation for the eigenmode that describes ENSO in each model is the same. The optimal forcing pattern, however, does vary from model to model, and depends on air–sea interaction processes.

Estimates of the stochastic component of forcing were obtained from atmospheric analyses and the projection of the dominant optimal forcing pattern from each model onto this component of the forcing was computed. It was found that each of the optimal forcing patterns identified may be present in nature and all are equally likely. The existence of a dominant optimal forcing pattern is explored in terms of the effective dimension of the coupled system using the method of balanced truncation, and was found to be O(1) for the models used here. The implications of this important result for ENSO prediction and predictability are discussed.
Atmospheric Teleconnection over Eurasia Induced by Aerosol Radiative Forcing during Boreal Spring
Authors: Kim Maeng-Ki , Lau William K. M. , Chin Mian , Kim Kyu-Myong , Sud Y. C. , Walker Greg K.
Published: September 2006

The direct effects of aerosols on global and regional climate during boreal spring are investigated based on numerical simulations with the NASA Global Modeling and Assimilation Office finite-volume general circulation model (fvGCM) with Microphyics of Clouds with the Relaxed–Arakawa Schubert Scheme (McRAS), using aerosol forcing functions derived from the Goddard Ozone Chemistry Aerosol Radiation and Transport model (GOCART).

The authors find that anomalous atmospheric heat sources induced by absorbing aerosols (dust and black carbon) excite a planetary-scale teleconnection pattern in sea level pressure, temperature, and geopotential height spanning North Africa through Eurasia to the North Pacific. Surface cooling due to direct effects of aerosols is found in the vicinity and downstream of the aerosol source regions, that is, South Asia, East Asia, and northern and western Africa. Significant atmospheric heating is found in regions with large loading of dust (over northern Africa and the Middle East) and black carbon (over Southeast Asia). Paradoxically, the most pronounced feature in aerosol-induced surface temperature is an east–west dipole anomaly with strong cooling over the Caspian Sea and warming over central and northeastern Asia, where aerosol concentrations are low. Analyses of circulation anomalies show that the dipole anomaly is a part of an atmospheric teleconnection pattern driven by atmospheric heating anomalies induced by absorbing aerosols in the source regions, but the influence was conveyed globally through barotropic energy dispersion and sustained by feedback processes associated with the regional circulations.

The surface temperature signature associated with the aerosol-induced teleconnection bears striking resemblance to the spatial pattern of observed long-term trend in surface temperature over Eurasia. Additionally, the boreal spring wave train pattern is similar to that reported by Fukutomi et al. associated with the boreal summer precipitation seesaw between eastern and western Siberia. The results of this study raise the possibility that global aerosol forcing during boreal spring may play an important role in spawning atmospheric teleconnections that affect regional and global climates.
The Impact of Tropical Atlantic Freshwater Fluxes on the North Atlantic Meridional Overturning Circulation
Authors: Spence J. Paul , Weaver Andrew J.
Published: September 2006

The influence of ENSO-related changes in the Atlantic-to-Pacific freshwater budget on the North Atlantic meridional overturning is examined using the University of Victoria (UVic) Earth System Climate Model. The initial analysis of freshwater fluxes in the 50-yr NCEP–NCAR (NCEP50) reanalysis product and Global Precipitation Climatology Project (GPCP) dataset reveals that the transport of water vapor out of the tropical Atlantic drainage basin is enhanced during El Niño phases and reduced during La Niña phases; a one standard deviation in the Southern Oscillation index alters the tropical Atlantic freshwater balance by about 0.09 Sv (Sv ≡ 106 m3 s−1). A weaker link with ENSO is found in the 40-yr ECMWF Re-Analysis (ERA-40), although its usefulness is severely limited by a strong and spurious trend in tropical precipitation. Model results suggest that tropical Atlantic salinity anomalies generated with the frequency and amplitude of ENSO tend not to impact deep-water formation as they are diluted en route to the North Atlantic. Lower frequency, decadal time-scale anomalies, however, do have an impact, albeit weak, on the rate of North Atlantic Deep Water formation. In addition, and contrary to earlier results, it is found that even a shift of the tropical Atlantic freshwater balance toward permanent El Niño conditions only slightly mitigates the transient reduction of North Atlantic Deep Water formation associated with the increase of anthropogenic greenhouse gases. Taken together, the results suggest that the poleward propagation of salinity anomalies from the tropical Atlantic, associated with changes in ENSO, should not be considered a significant mechanism for the variability of the North Atlantic meridional overturning in the present and foreseeable future climate.
Global Climate and Ocean Circulation on an Aquaplanet Ocean–Atmosphere General Circulation Model
Authors: Smith Robin S. , Dubois Clotilde , Marotzke Jochem
Published: September 2006

A low-resolution coupled ocean–atmosphere general circulation model (OAGCM) is used to study the characteristics of the large-scale ocean circulation and its climatic impacts in a series of global coupled aquaplanet experiments. Three configurations, designed to produce fundamentally different ocean circulation regimes, are considered. The first has no obstruction to zonal flow, the second contains a low barrier that blocks zonal flow in the ocean at all latitudes, creating a single enclosed basin, while the third contains a gap in the barrier to allow circumglobal flow at high southern latitudes.

Warm greenhouse climates with a global average air surface temperature of around 27°C result in all cases. Equator-to-pole temperature gradients are shallower than that of a current climate simulation. While changes in the land configuration cause regional changes in temperature, winds, and rainfall, heat transports within the system are little affected. Inhibition of all ocean transport on the aquaplanet leads to a reduction in global mean surface temperature of 8°C, along with a sharpening of the meridional temperature gradient. This results from a reduction in global atmospheric water vapor content and an increase in tropical albedo, both of which act to reduce global surface temperatures.

Fitting a simple radiative model to the atmospheric characteristics of the OAGCM solutions suggests that a simpler atmosphere model, with radiative parameters chosen a priori based on the changing surface configuration, would have produced qualitatively different results. This implies that studies with reduced complexity atmospheres need to be guided by more complex OAGCM results on a case-by-case basis.
Is the Thermohaline Circulation Changing?
Authors: Latif M. , Böning C. , Willebrand J. , Biastoch A. , Dengg J. , Keenlyside N. , Schweckendiek U. , Madec G.
Published: September 2006

Analyses of ocean observations and model simulations suggest that there have been considerable changes in the thermohaline circulation (THC) during the last century. These changes are likely to be the result of natural multidecadal climate variability and are driven by low-frequency variations of the North Atlantic Oscillation (NAO) through changes in Labrador Sea convection. Indications of a sustained THC weakening are not seen during the last few decades. Instead, a strengthening since the 1980s is observed. The combined assessment of ocean hydrography data and model results indicates that the expected anthropogenic weakening of the THC will remain within the range of natural variability during the next several decades.
Low-Frequency Variations of Surface Temperature in Observations and Simulations
Authors: DelSole Timothy
Published: September 2006

This paper documents the low-frequency (i.e., decadal) variations of surface temperature for the period 1899–1998 in observations, and in simulations conducted as part of the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). The space–time structure of low-frequency variations is extracted using optimal persistence analysis, which is a technique that linearly decomposes a vector time series into a set of uncorrelated components, ordered such that the first component maximizes the decorrelation time, the second maximizes the decorrelation time subject to being uncorrelated with the first, and so on. The results suggests that only the first two optimal persistence patterns (OPPs) in the observation-based record are statistically distinguishable from white noise. These two components can reproduce the spatial structure of local linear trends over various multidecadal periods, indicating that they give an efficient representation of the observed change in surface temperature. In contrast, most simulations suggest the existence of a single physically significant OPP, all with qualitatively similar time series but each with somewhat different spatial structure. The leading OPP computed from the full model grid is surprisingly consistent with the leading OPP computed from the observation-based grid with missing data masked out, suggesting that the observation-based grid does not pose a serious barrier to extracting the dominant low-frequency variations in the global climate system. The regions in which the leading optimal persistence patterns agree in their predictions of warming coincides with the regions in which warming has in fact been observed to occur.
Contributions of Wind Forcing and Surface Heating to Interannual Sea Level Variations in the Atlantic Ocean
Authors: Cabanes Cécile , Huck Thierry , Colin de Verdière Alain
Published: September 2006

Interannual sea surface height variations in the Atlantic Ocean are examined from 10 years of high-precision altimeter data in light of simple mechanisms that describe the ocean response to atmospheric forcing: 1) local steric changes due to surface buoyancy forcing and a local response to wind stress via Ekman pumping and 2) baroclinic and barotropic oceanic adjustment via propagating Rossby waves and quasi-steady Sverdrup balance, respectively. The relevance of these simple mechanisms in explaining interannual sea level variability in the whole Atlantic Ocean is investigated. It is shown that, in various regions, a large part of the interannual sea level variability is related to local response to heat flux changes (more than 50% in the eastern North Atlantic). Except in a few places, a local response to wind stress forcing is less successful in explaining sea surface height observations. In this case, it is necessary to consider large-scale oceanic adjustments: the first baroclinic mode forced by wind stress explains about 70% of interannual sea level variations in the latitude band 18°–20°N. A quasi-steady barotropic Sverdrup response is observed between 40° and 50°N.
A Multithickness Sea Ice Model Accounting for Sliding Friction
Authors: Wilchinsky Alexander V. , Feltham Daniel L. , Miller Paul A.
Published: September 2006

A multithickness sea ice model explicitly accounting for the ridging and sliding friction contributions to sea ice stress is developed. Both ridging and sliding contributions depend on the deformation type through functions adopted from the Ukita and Moritz kinematic model of floe interaction. In contrast to most previous work, the ice strength of a uniform ice sheet of constant ice thickness is taken to be proportional to the ice thickness raised to the 3/2 power, as is revealed in discrete element simulations by Hopkins. The new multithickness sea ice model for sea ice stress has been implemented into the Los Alamos “CICE” sea ice model code and is shown to improve agreement between model predictions and observed spatial distribution of sea ice thickness in the Arctic.
Aegean Sea Water Masses during the Early Stages of the Eastern Mediterranean Climatic Transient (1988–90)
Authors: Gertman I. , Pinardi N. , Popov Y. , Hecht A.
Published: September 2006

The Aegean water masses and circulation structure are studied via two large-scale surveys performed during the late winters of 1988 and 1990 by the R/V Yakov Gakkel of the former Soviet Union. The analysis of these data sheds light on the mechanisms of water mass formation in the Aegean Sea that triggered the outflow of Cretan Deep Water (CDW) from the Cretan Sea into the abyssal basins of the eastern Mediterranean Sea (the so-called Eastern Mediterranean Transient). It is found that the central Aegean Basin is the site of the formation of Aegean Intermediate Water, which slides southward and, depending on their density, renews either the intermediate or the deep water of the Cretan Sea. During the winter of 1988, the Cretan Sea waters were renewed mainly at intermediate levels, while during the winter of 1990 it was mainly the volume of CDW that increased. This Aegean water mass redistribution and formation process in 1990 differed from that in 1988 in two major aspects: (i) during the winter of 1990 the position of the front between the Black Sea Water and the Levantine Surface Water was displaced farther north than during the winter of 1988 and (ii) heavier waters were formed in 1990 as a result of enhanced lateral advection of salty Levantine Surface Water that enriched the intermediate waters with salt. In 1990 the 29.2 isopycnal rose to the surface of the central basin and a large volume of CDW filled the Cretan Basin. It is found that, already in 1988, the 29.2 isopycnal surface, which we assume is the lowest density of the CDW, was shallower than the Kassos Strait sill and thus CDW egressed into the Eastern Mediterranean.
Decadal Variability in the Large-Scale Sea Surface Height Field of the South Pacific Ocean: Observations and Causes
Authors: Qiu Bo , Chen Shuiming
Published: September 2006

Large-scale sea surface height (SSH) changes in the extraequatorial South Pacific Ocean are investigated using satellite altimetry data of the past 12 yr. The decadal SSH signals in the 1990s were dominated by an increasing trend in the 30°–50°S band and a decreasing trend in the central South Pacific Ocean poleward of 50°S. In recent years since 2002 there has been a reversal in both of these trends. Spatially varying low-frequency SSH signals are also found in the tropical region of 10°–25°S where the decadal SSH trend is negative in the eastern basin, but positive in the western basin. To clarify the causes for these observed spatially varying SSH signals, a 1½-layer reduced-gravity model that includes the wind-driven baroclinic Rossby wave dynamics and the responses forced by SSH changes along the South American coast was adopted. The model hindcasts the spatially varying decadal trends in the midlatitude and the eastern tropical regions well. Accumulation of the wind-forced SSH anomalies along Rossby wave characteristics is found to be important for both previously reported long-term trends and their reversals in recent years. The boundary forcing associated with the time-varying SSH signals along the South American coast is crucial for understanding the observed SSH signals of all time scales in the eastern tropical South Pacific basin, but it has little impact upon the midlatitude interior SSH signals.
Altimeter and Current Meter Observations of Internal Tides: Do They Agree?
Authors: Chiswell Stephen M.
Published: September 2006

Baroclinic tides can be observed both remotely from the Ocean Topography Experiment (TOPEX)/Poseidon (T/P) altimeter and in situ using current meters. However, it is rare that current meter moorings have high vertical resolution and are located under T/P ground tracks so that a direct comparison can be made between the two methods of observations. Here, data from a current meter mooring directly under a T/P ground track off the Bounty Plateau, New Zealand, are used to obtain energy estimates of the first baroclinic mode. These estimates are compared with those calculated from the T/P surface elevation. The two methods return estimates of the internal tide that are in agreement in phase and direction but have about a factor-of-2 difference in amplitude (and a factor-of-4 difference in energy); the flux estimates are 787 and 170 W m−1, respectively. Uncertainties in these estimates are relatively large, and there is a low but not negligible probability that the differences are entirely due to measurement error. However, there are other reasons that might explain the differences in the estimates. It may be that the baroclinic tide is highly modulated in time and the current meters were deployed during a period of relatively low amplitude.
Leadership and management in UK local government: a role for elected mayors?
Authors: Fenwick John , Elcock Howard , McMillan Janice
Published: September 2006

The paper assesses the impact of the elected executive mayor on leadership and management in UK local government. After exploring the new executive arrangements introduced by the Local Government Act 2000, the three themes of governing, governance and allegiance within mayoral councils are discussed in detail. Principally using the results of interviews with a group of the mayors first elected in 2002, the paper suggests that the directly elected mayor has an enhanced individual role in the leadership of the local council, that elected mayors increasingly coordinate the efforts of external partners in the wider governance of the area, that new and potentially problematic relationships are developed with elected councillors and with senior managers, and that there is a changed local political context in which the mayor must now operate. The elected mayor is seen as both leader and manager. It is suggested that mayors have sought a new direct relationship with the public, and that this has implications for the continued role of other local representatives. Finally, the prospects for extending the mayoral experiment under the ‘modernization’ framework of the government re-elected in May 2005 are examined. Although the mayoral initiative has been adopted in only a small number of councils, it is concluded that leadership and management of the local authority are significantly changed within those areas.
Identity, Institutions and Systemic Change
Authors: Ruth Damian
Published: September 2006

This article reports findings related to race, ethnicity and institutional type from a more extensive study on the perceptions of South African academics on academic workload. An attempt in a South African university department to distribute workload fairly indicated this task involved personal and sensitive concerns, which often had to do with biographical and situational variables. That attempt inspired this study which investigated the relationship between social group and institutional type, and views on the composition and distribution of aspects of academic work, determinants of teaching load, determinants of remuneration, the purpose of staff development programmes, and decision-making in departments. It was found that social group and institutional type are significant factors in views on the composition and distribution of academic work, on remuneration and on the purpose of staff development programmes. There is a disparity between what all groups think should be the case and what actually is the case, and yet there is a general satisfaction with decision-making processes. These findings suggest that the systemic and organizational transformation of higher education in South Africa is embedded in the complexities of social identity and institutional type. This has implications for the management and leading of systemic transformation in other countries.
Emerging Voices on Teacher Leadership
Authors: Grant Carolyn
Published: September 2006

Prior to 1994, the education system of South Africa was characterized by a hierarchical and bureaucratic style of management as well as a situation where white schools were the key beneficiaries of resources and black schools massively disadvantaged. In 1996 a national task team made strategic proposals for education management capacity, including a self-management approach to schools and implicitly supporting the notion of teacher leadership for the new dispensation (Department of Education, 1996). Despite this enabling framework, however, few teachers appear to be embracing a teacher leader role and it is an unexplored area of research in South Africa. This article reports on the experiences of 11 university tutors, many of whom are also classroom-based teachers, around the concept of teacher leader, during a professional development initiative which ran parallel with their teaching on a postgraduate module. The article identifies how tutors develop their understanding of the concept of teacher leader during the initiative, explores the factors which may support or impede the take-up of this concept by teachers and argues that, without teacher leadership, the transformation of South African schools into professional learning communities is unlikely to occur.
Never say die
Authors: Page Susie
Published: September 2006

The aim of this paper is to convey the usefulness of an ethnographic approach in understanding the clinical practice of Cardiopulmonary resuscitation (CPR). One of the study findings, concerning the interplay of politics, power relationships and commerce around CPR practice, is used to demonstrate, albeit briefly, how current CPR policy has been driven by perceptions of risk.
Crack opening displacements during fatigue crack growth in Ti–SiC fibre metal matrix composites by X-ray tomography
Authors: Withers P. J. , Bennett J. , Hung Y.-C. , Preuss M.
Published: September 2006

High spatial resolution X-ray microtomography has been used to map the variation of crack opening displacement (COD) across matrix cracks in unidirectional Ti–6Al–4V/SCS-6 SiC fibre composites. These show the crack front to bow out between fibres as the crack emerges from a ply and to advance preferentially towards the fibres when located between plies. Quantitative image analysis of 3D volume reconstructions has enabled the COD to be measured at Kmin, Kmid and Kmax. Hysteresis in crack opening was observed during the fatigue cycle (loads applied statically). Very little variation in COD has been observed parallel to the crack front irrespective of proximity to the bridging fibres. The changes in COD relative to the initial residual opening at Kmin are not inconsistent with being proportional to the square root of the distance from the crack tip. Considerable crack blunting was observed during an overload leading to a significant residual crack opening upon unloading.
Artefacts in X-ray microtomography of materials
Authors: Davis G. R. , Elliott J. C.
Published: September 2006

X-ray microtomography is becoming an increasingly popular tool in the study of microstructure and failure mechanisms in biological and engineering materials, producing three-dimensional (3D) maps of the X-ray linear attenuation coefficient. Limitations of the technique are due to, for example, limited X-ray flux, use of polychromatic radiation (in laboratory systems), finite resolution, discrete sampling and X-ray scatter. These give rise to artefacts in the reconstructed image. Knowledge of these artefacts helps to distinguish them from real features and is important for optimising experimental design so as to minimise their effect on the results. To aid identification, artefacts were simulated computationally using an analytical phantom projection generator. Streak, ring, motion and beam hardening artefacts are considered as well as the results of errors in the centre of rotation and missing information in cone beam geometry. Examples of tomographic images of real materials specimens with motion and beam hardening artefacts as well as centring errors are also shown.
X-ray microtomographic studies of novel radio-opaque polymeric materials for dental applications
Authors: Anderson P. , Ahmed Y. , Patel M. P. , Davis G. R. , Braden M.
Published: September 2006

Radio-opacity may be desirable for polymeric materials used in medical and dental applications. However, problems arise when radio opaque metallic salts are blended with polymer powders before polymerisation. A novel alternative approach is to use polymers in which the X-ray opaque element is chemically incorporated within the monomer unit. The present study investigates two potential materials, a barium methacrylate monomer which is a powder at room temperature and a tin methacrylate monomer which is liquid at room temperature, both then mixed with a methacrylate diluent. X-ray microtomography revealed that the powdered barium methacrylate material did not blend well and particles of high X-ray attenuation were formed. Whereas, X-ray microtomography images of the tin methacrylate material revealed that the mixture was completely homogenous. The possible application of these two materials as a pit and fissure sealant is described.
Thermodynamic evidence for a poisoning mechanism in the Al–Si–Ti system
Authors: Quested T. E. , Dinsdale A. T. , Greer A. L.
Published: September 2006

The poisoning of grain refinement in aluminium alloys owing to the presence of silicon is investigated using CALPHAD based thermodynamic modelling software. The existence of primary phases other than α-aluminium, namely TiSi2 and TiSi, which are stable at typical melt holding temperatures, is consistent with microstructural observations of other researchers. The compositional and temperature range of these phases are calculated. The software is also used to determine the effect of silicon and titanium additions on the growth rates of α-aluminium grains via the growth restriction parameter Q. These results are used to explain poisoning in silicon containing foundry alloys via a thorough review and discussion of the relevant literature.
Effect of some thermal treatments on interface adhesion toughness of various thick thermal spray coatings
Authors: Chicot D. , Marot G. , Araujo P. , Horny N. , Tricoteaux A. , Staia M. H. , Lesage J.
Published: September 2006

Interfacial indentation is used to create and propagate a crack in the interface plane between a coating and its substrate. It has been shown earlier that this methodology allows the measurement of an apparent interface toughness, which can represent the adhesion of the coating to its substrate. In service thermal spray coatings are subjected to various external influences, which could be detrimental to their adhesion, e.g. thermal shock, fatigue, wear, corrosion and combinations of these. The objective of the present work is to study some of these effects and their influence on the interface adhesion toughness of various substrate/coating systems based on new phenomenological approaches to the residual stress state existing in the coating: (a) annealing treatment – for as sprayed specimen, it was first shown that the interface toughness is directly proportional to the reciprocal of the squared coating thickness. Extrapolated to an infinite thickness, the toughness could be assumed then to represent the adhesive properties of the coating. The same tests, performed on annealed samples, for which, it was expected to see significant modification of the residual stresses state, led to an apparent interface toughness independent of the coating thickness. Moreover, this value corresponds to the value extrapolated for the as sprayed specimen. The difference between the calculated values of Kca on both as sprayed samples and on annealed ones is discussed in terms of a stress amplitude factor defined as the difference between the residual stresses in the coating and in the substrate. The obtained result is very important since it confirms that there exists a value which, being independent on the thickness, can represent the adhesion of the coating; (b) hydrogen contamination – using this methodology, it was found that, besides the embrittlement of the coating, adhesion was also affected because the critical load necessary to initiate a crack at the interface was reduced in the presence of hydrogen. Using apparent interface toughness, it was also possible to compare the effect of hydrogen with that of the residual stresses (thickness) effect, according to the stress amplitude factor at the interface and to the capability of the substrate and/or the coating to trap atoms of hydrogen in the neighbourhood of the interface; (c) thermal treatments – in addition, it is demonstrated here that the methodology allows quantification of the effects of the thermal treatments such as thermal shock or thermal cycling on the adhesion properties of the coatings. It was shown that thermal treatments for particular conditions of time or temperature lead to a reinforcement of the metallurgical bond and, consequently, to an increase in the adhesion of the coating on its substrate.
Glow discharge modified tissue culture polystyrene: Role of surface chemistry in cellular attachment and proliferation
Authors: Mitchell S. A. , Davidson M. R. , Bradley R. H.
Published: September 2006

A radio frequency glow discharge has been used to selectively deposit non-polar hydrocarbon films onto tissue culture grade polystyrene surfaces. The resulting surfaces have been studied using X-ray photoelectron spectroscopy, contact angle analysis and atomic force microscopy. Regions with differing surface chemistry and polarity have been produced on the same substrate using a simple masking technique and allowed the spatially controlled attachment of mammalian cells. The attachment of cells to plasma modified tissue culture polystyrene surfaces has been correlated to the concentration of specific oxygen functional groups.
Ion nitrided AISI H13 tool steel Part 2 – High temperature performance under sliding wear conditions
Authors: Cruz M. R. , Staia M. H.
Published: September 2006

In the present work, study on a systematic variation of the processing parameters such as gas mixture, time of nitriding and current density has been carried out in order to determine how these will influence the sliding wear behaviour of plasma nitrided layers on AISI H13. Optical profilometry and scanning electron microscopy were used to characterise the worn sample and to determine the wear mechanism. The results revealed a strong influence of the current density on the formation of different diffusion and nitrided layers, which explained the wear behaviour of the studied samples, especially for those tested at room temperature. It was found that the wear volume of the nitrided samples without the existence of a compound layer was ∼200 times smaller than the wear volume of the untreated samples and nearly seven times smaller than the wear volume of nitrided samples when the compound layer was present. When the tests were carried out at 300°C, the wear behaviour was worse for the nitrided samples than for the untreated ones, owing to the formation of higher amount of debris as a consequence of the breakdown of the compound layer and the subsequent removal of the enriched Cr–N from the ferritic matrix, generating a severe abrasion wear mechanism. All the samples tested at 600°C presented a similar tribological behaviour irrespective of the processing parameters values chosen for nitriding, as a consequence of the formation of a uniform and ‘lubricious’ iron oxide layer which, however, was insufficient to protect the steel against wear at this temperature to the levels which were obtained for the samples tested at room temperature.
Disturbance of systemic antioxidant profile in nonsmall cell lung carcinoma
Authors: Ho J. C. , Chan-Yeung M. , Ho S. P. , Mak J. C. , Ip M. S. , Ooi G. C. , Wong M. P. , Tsang K. W. , Lam W. K.
Published: September 2006

The present study aimed to determine the alterations of antioxidant activities in erythrocytes from patients with nonsmall cell lung carcinoma (NSCLC).

A comparative study of the systemic antioxidant activities in red blood cell lysate from subjects with NSCLC and healthy control subjects was conducted. The antioxidants catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) were measured using chemical kinetic reactions under spectrophotometry.

In total, 189 cases of mostly advanced-stage IIIB or stage IV NSCLC and 202 healthy controls were studied. In subjects with lung cancer, there was similar catalase activity, lower SOD activity (median (interquartile range) 13.4 (9.0–27.2)versus48.7 (27.0–64.3) U·(ghaemoglobulin(Hb)-1), and higher GPx activity (175.2 (126.6–288.3)versus49.2 (39.5–59.2) mU·(gHb)-1) compared with controls. The antioxidant activities in lung cancer subjects were not associated with age, sex, smoking status, or tumour cell types. However, more advanced disease (stage IV compared with stage IIIB) was associated with lower SOD activity. Using multivariable analysis, the presence of lung cancer independently predicted SOD and GPx activities.

In conclusion, nonsmall cell lung carcinoma in Chinese subjects is associated with alterations in systemic antioxidant activities, which may play an important role in carcinogenesis.
Expression of histo-blood group antigens in bronchial squamous metaplasia
Authors: Sánchez-Mora N. , Cebollero Presmanes M. , Monroy V. , Herranz Aladro M. , Álvarez-Fernández E.
Published: September 2006

The aim of the present study was to evaluate the expression of blood group antigens in squamous bronchial metaplasia in order to determine whether this factor could identify patients at risk of lung cancer.

In total, 100 bronchial biopsies were included in the present study. The cases were classified according to the World Health Organization grading system. Immunohistochemical stains for histo-blood groups A and B, and reactivity tests to p53 and the cellular proliferation index were performed.

A total of 56 (56%) patients belonged to blood group A. Among them, six (10.7%) patients who did not express antigen in squamous metaplasia, showed carcinoma at the moment of the biopsy (n = 3) or developed synchronous lung carcinoma (n = 3). A total of nine (9%) patients belonged to blood group B. Loss of antigenic expression was observed in five cases. All of them developed synchronous lung carcinoma. The patients with low- and high-grade dysplasia developed lung cancer in 71 and 100% of the cases, respectively.

In conclusion, the findings of the present study suggest that the loss of histo-blood antigens expression is an event in the carcinogenesis of bronchial mucosa and it is usually associated with high-grade lesions and hyperproliferative activity.
Estimated numbers and prevalence of PI*S and PI*Z deficiency alleles of α1-antitrypsin deficiency in Asia
Authors: de Serres F. J. , Blanco I. , Fernández-Bustillo E.
Published: September 2006

The current study focuses on updating estimates of the numbers of individuals carrying the two most common deficiency alleles, protease inhibitor (PI)*S and PI*Z, for α1-antitrypsin deficiency (AT-D) in 20 Asian countries.

A total of 170 cohorts with 31,177 individuals were selected from 20 Asian countries. The total AT-D populations in the countries selected were: 7,264 ZZ; 36,754 SZ; 6,672,479 MZ; 46,492 SS; and 16,881,108 MS. Marked differences among the Asian countries and regions were also found for the prevalence of the deficiency alleles PI*S and PI*Z. These numbers demonstrate that AT-D is not just a genetic disease that affects smaller numbers than various countries, for example, in Europe.

There were marked differences between the prevalence of the PI*S and PI*Z deficiency alleles among these 20 Asian countries as well as among the countries within a given geographic region in Asia. The largest numbers of ZZ phenotypes (3,000–14,000) were in Afghanistan, Pakistan, Saudi Arabia and Thailand; with <1,700 in each of the remaining countries.
Surfactant protein C mutations in sporadic forms of idiopathic interstitial pneumonias
Authors: Markart P. , Ruppert C. , Wygrecka M. , Schmidt R. , Korfei M. , Harbach H. , Theruvath I. , Pison U. , Seeger W. , Guenther A. , Witt H.
Published: September 2006

Interstitial pneumonias have recently been associated with mutations in the gene encoding surfactant protein C (SFTPC). In particular,SFTPCmutations have been reported in a number of familial forms of pulmonary fibrosis and in infants with interstitial lung diseases. The present study searched forSFTPCmutations in adult patients with sporadic idiopathic interstitial pneumonia.

In total, 35 adult patients with sporadic idiopathic interstitial pneumonia and 50 healthy subjects were investigated forSFTPCmutations by direct DNA sequencing. Of the patients with sporadic idiopathic interstitial pneumonia, 25 suffered from idiopathic pulmonary fibrosis and 10 patients from nonspecific interstitial pneumonia.

Only two frequent nonsynonymous variants, T138N and S186N, were detected. Allele frequencies of both variations as well as of other identified noncoding alterations did not differ significantly between the diverse patient groups and control subjects.

In conclusion, mutations in the gene encoding surfactant protein C are not common in sporadic cases of idiopathic pulmonary fibrosis and nonspecific interstitial pneumonia, suggesting that the mutated gene does not play an important role in the pathogenesis of these forms of idiopathic interstitial pneumonia.
The influence of patent foramen ovale on oxygen desaturation in obstructive sleep apnoea
Authors: Johansson M. C. , Eriksson P. , Peker Y. , Hedner J. , Råstam L. , Lindblad U.
Published: September 2006

Obstructive sleep apnoea (OSA) is associated with oxygen desaturation to a varying degree. A patent foramen ovale (PFO) may allow interatrial right-to-left shunting. The hypothesis of the current study was that oxygen desaturation will occur more often, in proportion to the frequency of respiratory disturbances, in OSA subjects with PFO than in those without.

In a group of 209 subjects diagnosed with OSA, the proportion of desaturation to respiratory events was calculated as the ratio of oxygen desaturation index (ODI)/apnoea–hypopnoea index (AHI). A total of 15 cases with high proportional desaturation (ODI/AHI ≥0.66) were individually matched with 15 controls with low proportional desaturation (ODI/AHI ≤0.33), all without pulmonary disease. PFO was assessed with contrast transoesophageal echocardiography and considered large when ≥20 bubbles passed over from the right to the left atrium after a single injection.

The prevalence of large PFO was nine out of 15 (60%) in the high proportional desaturation groupversustwo out of 15 (13%) in the low proportional desaturation group. The median number of passing bubbles was positively correlated to minimum oxygen saturation among those with PFO.

In conclusion, oxygen desaturation occurs more often, in proportion to the frequency of respiratory disturbances, in obstructive sleep apnoea subjects with a patent foramen ovale than in those without.
Economic evaluation of adherence to treatment guidelines in nonintensive care pneumonia
Authors: Menéndez R. , Reyes S. , Martínez R. , de la Cuadra P. , Manuel Vallés J. , Vallterra J.
Published: September 2006

Guidelines have been developed to improve the treatment of community-acquired pneumonia (CAP) but information regarding their influence on costs is lacking. The aim of the present study was to conduct a cost-effectiveness analysis of CAP treatment from the hospital perspective when adhering to Spanish guidelines.

A prospective cohort study was performed in 271 patients with CAP admitted to a tertiary-care hospital, not needing intensive care. Collected data included patients' characteristics, comorbidity, initial risk class, resource use (medication, blood and microbiological analyses, and radiology) and economic data. Antimicrobial treatment was recorded as adherent or nonadherent to Spanish guidelines. Outcome measures were mortality and readmission at 30 days.

The median cost for adherent treatment was 1,665.5versus1,710.5 Euros for nonadherent treatment. Mortality and readmission were 10% and 2.1% for adherent treatmentversus13.6% and 6.2% for nonadherent treatment. The cost-effectiveness ratio was 2,277 Euros per expected cure for patients treated according to the guidelines and 2,567 Euros per expected cure for the nonadherence group. The incremental cost-effectiveness ratio showed that adherence to treatment guidelines saved 1,121 Euros per patient cured compared with nonadherence. The sensitivity analysis demonstrated that the findings were robust.

An antimicrobial treatment according to guidelines is the dominant alternative due to its cost-effectiveness.
Obstructive sleep apnoea and oral breathing in patients free of nasal obstruction
Authors: Koutsourelakis I. , Vagiakis E. , Roussos C. , Zakynthinos S.
Published: September 2006

Although there is an association between nasal obstruction, oral breathing and obstructive sleep apnoea syndrome (OSAS), it remains unknown whether increased oral breathing occurs in patients with OSAS who are free of nasal obstruction. The present study evaluated the relationship between breathing route and OSAS in patients without nasal obstruction.

The breathing route of 41 snorers (25 male; aged 26–77 yrs) with normal nasal resistance was examined during overnight polysomnography using a nasal cannula/pressure transducer and an oral thermistor.

In total, 28 patients had OSAS (apnoeics) and 13 patients were simple snorers. Apnoeics had a higher percentage of oral and oro-nasal breathing epochs. Oral and oro-nasal breathing epochs were positively related with apnoea/hypopnoea index (AHI) and duration of apnoeas/hypopnoeas and inversely related to oxygen saturation. Additionally, oro-nasal breathing epochs correlated with body mass index (BMI). In multiple linear regression analysis, oral breathing epochs were independently related only to AHI (r2 = 0.443), and oro-nasal breathing epochs were independently related to AHI (r2 = 0.736) and BMI (r2 = 0.036).

In conclusion, apnoeics spent more time breathing orally and oro-nasally than simple snorers, and the apnoea/hypopnoea index is a major determinant of the time spent breathing orally and oro-nasally.
Hot biopsy forceps in the diagnosis of endobronchial lesions
Authors: Tremblay A. , Michaud G. , Urbanski S. J.
Published: September 2006

Electrocoagulation bronchoscopy biopsy forceps may prevent bleeding, but could also impair the quality of the specimens obtained.

Patients with endobronchial lesions during bronchoscopy underwent six endobronchial biopsies each with a hot biopsy forceps, alternating between with electrocoagulation (“hot”) and without (“cold”). Bleeding was quantified on a scale of 1–4, with 1 being no bleeding. The generator was set on “soft coagulation” mode, with power settings of 40, 60, 80 and 100 W for each group of 10 patients in a sequential fashion. Clinical pathology results were recorded before samples were reviewed by a second, blinded, pulmonary pathologist.

A total of 39 patients with 40 endobronchial lesions had six biopsies performed (one patient had only four samples taken), giving a total of 238 biopsy samples. Concordance between hot and cold samples was 92.5% for the clinical pathologist and 87% for the blinded pathologist. Paired analysis suggested lower average bleeding score with the use of hot forceps. Overall bleeding rates for cold and hot biopsies, respectively, were as follows: grade 1: 30.3 and 41.2%; grade 2: 62.2 and 49.6%; grade 3: 7.6 and 9.2%; and grade 4: 0 and 0%.

In conclusion, the use of hot biopsy forceps for endobronchial biopsy does not appear to have a negative impact on the pathological samples. Hot biopsy forceps showed a statistically significant reduction in bleeding score, which is unlikely to be of clinical significance.