bluuebunny/crossref_metadata_2025 huggingface dataset:
Tumor necrosis factor alpha and epidermal growth factor act additively to inhibit matrix gene expression by chondrocyte
Authors: Klooster Aaron R , Bernier Suzanne M
Published: January 2005

The failure of chondrocytes to replace the lost extracellular matrix contributes to the progression of degenerative disorders of cartilage. Inflammatory mediators present in the joint regulate the breakdown of the established matrix and the synthesis of new extracellular matrix molecules. In the present study, we investigated the effects of tumor necrosis factor alpha (TNF-α) and epidermal growth factor (EGF) on chondrocyte morphology and matrix gene expression. Chondrocytes were isolated from distal femoral condyles of neonatal rats. Cells in primary culture displayed a cobblestone appearance. EGF, but not TNF-α, increased the number of cells exhibiting an elongated morphology. TNF-α potentiated the effect of EGF on chondrocyte morphology. Individually, TNF-α and EGF diminished levels of aggrecan and type II collagen mRNA. In combination, the effects of TNF-α and EGF were additive, indicating the involvement of discrete signaling pathways. Cell viability was not compromised by TNF-α or by EGF, alone or in combination. EGF alone did not activate NF-κB or alter NF-κB activation by TNF-α. Pharmacologic studies indicated that the effects of TNF-α and EGF alone or in combination were independent of protein kinase C signaling, but were dependent on MEK1/2 activity. Finally, we analyzed the involvement of Sox-9 using a reporter construct of the 48 base pair minimal enhancer of type II collagen. TNF-α attenuated enhancer activity as expected; in contrast, EGF did not alter either the effect of TNF-α or basal activity. TNF-α and EGF, acting through distinct signaling pathways, thus have additive adverse effects on chondrocyte function. These findings provide critical insights into the control of chondrocytes through the integration of multiple extracellular signals.
Rheumatoid arthritis synovium contains plasmacytoid dendritic cells
Authors: Cavanagh Lois L , Boyce Amanda , Smith Louise , Padmanabha Jagadish , Filgueira Luis , Pietschmann Peter , Thomas Ranjeny
Published: January 2005

We have previously described enrichment of antigen-presenting HLA-DR+ nuclear RelB+ dendritic cells (DCs) in rheumatoid arthritis (RA) synovium. CD123+HLA-DR+ plasmacytoid DCs (pDCs) and their precursors have been identified in human peripheral blood (PB), lymphoid tissue, and some inflamed tissues. We hypothesized recruitment of pDCs into the inflamed RA synovial environment and their contribution as antigen-presenting cells (APCs) and inflammatory cells in RA. CD11c+ myeloid DCs and CD123+ pDCs were compared in normal and RA PB, synovial fluid (SF), and synovial tissue by flow cytometry, immunohistochemistry, and electron microscopy and were sorted for functional studies. Nuclear RelB-CD123+ DCs were located in perivascular regions of RA, in a similar frequency to nuclear RelB+CD123- DCs, but not normal synovial tissue sublining. Apart from higher expression of HLA-DR, the numbers and phenotypes of SF pDCs were similar to those of normal PB pDCs. While the APC function of PB pDCs was less efficient than that of PB myeloid DCs, RA SF pDCs efficiently activated resting allogeneic PB T cells, and high levels of IFN-γ, IL-10, and tumor necrosis factor α were produced in response to incubation of allogeneic T cells with either type of SF DCs. Thus, pDCs are recruited to RA synovial tissue and comprise an APC population distinct from the previously described nuclear RelB+ synovial DCs. pDCs may contribute significantly to the local inflammatory environment.
Chemokine receptors in the rheumatoid synovium: upregulation of CXCR5
Authors: Schmutz Caroline , Hulme Alison , Burman Angela , Salmon Mike , Ashton Brian , Buckley Christopher , Middleton Jim
Published: January 2005

In patients with rheumatoid arthritis (RA), chemokine and chemokine receptor interactions play a central role in the recruitment of leukocytes into inflamed joints. This study was undertaken to characterize the expression of chemokine receptors in the synovial tissue of RA and non-RA patients. RA synovia (n = 8) were obtained from knee joint replacement operations and control non-RA synovia (n = 9) were obtained from arthroscopic knee biopsies sampled from patients with recent meniscal or articular cartilage damage or degeneration. The mRNA expression of chemokine receptors and their ligands was determined using gene microarrays and PCR. The protein expression of these genes was demonstrated by single-label and double-label immunohistochemistry. Microarray analysis showed the mRNA for CXCR5 to be more abundant in RA than non-RA synovial tissue, and of the chemokine receptors studied CXCR5 showed the greatest upregulation. PCR experiments confirmed the differential expression of CXCR5. By immunohistochemistry we were able to detect CXCR5 in all RA and non-RA samples. In the RA samples the presence of CXCR5 was observed on B cells and T cells in the infiltrates but also on macrophages and endothelial cells. In the non-RA samples the presence of CXCR5 was limited to macrophages and endothelial cells. CXCR5 expression in synovial fluid macrophages and peripheral blood monocytes from RA patients was confirmed by PCR. The present study shows that CXCR5 is upregulated in RA synovial tissue and is expressed in a variety of cell types. This receptor may be involved in the recruitment and positioning of B cells, T cells and monocytes/macrophages in the RA synovium. More importantly, the increased level of CXCR5, a homeostatic chemokine receptor, in the RA synovium suggests that non-inflammatory receptor–ligand pairs might play an important role in the pathogenesis of RA.
Effect of adalimumab on neutrophil function in patients with rheumatoid arthritis
Authors: Capsoni Franco , Sarzi-Puttini Piercarlo , Atzeni Fabiola , Minonzio Francesca , Bonara Paola , Doria Andrea , Carrabba Mario
Published: January 2005

Neutrophils are known to be targets for the biological activity of tumour necrosis factor (TNF)-α in the pathogenensis of rheumatoid arthritis (RA). Therefore, these cells may be among the targets of anti-TNF-α therapy. In this study we evaluated the effect of therapy with adalimumab (a fully human anti-TNF-α mAb; dosage: 40 mg subcutaneously every other week) on certain phenotypic and functional aspects of neutrophils obtained from 10 selected patients with RA and 20 healthy control individuals. Peripheral blood neutrophils were obtained at baseline and during anti-TNF-α therapy (2, 6 and 12 weeks after the first administration of adalimumab). All patients had been receiving a stable regimen of hydroxychloroquine, methotrexate and prednisone for at least 3 months before and during the study. Baseline neutrophil chemotaxis was significantly decreased in RA patients when compared with control individuals (P < 0.001). Two weeks after the first administration of adalimumab, chemotactic activity was completely restored, with no differences noted between patients and control individuals; these normal values were confirmed 6 and 12 weeks after the start of anti-TNF-α therapy. Phagocytic activity and CD11b membrane expression on neutrophils were similar between RA patients and control individuals; no modifications were observed during TNF-α neutralization. The production of reactive oxygen species, both in resting and PMA (phorbol 12-myristate 13-acetate)-stimulated cells, was significantly higher in RA patients at baseline (P < 0.05) and was unmodified by anti-TNF-α mAb. Finally, we showed that the activation antigen CD69, which was absent on control neutrophils, was significantly expressed on neutrophils from RA patients at baseline (P < 0.001, versus control individuals); however, the molecule was barely detectable on cells obtained from RA patients during adalimumab therapy. Because CD69 potentially plays a role in the pathogenesis of arthritis, our findings suggest that neutrophils are among the targets of anti-TNF-α activity in RA and may provide an insight into a new and interesting mechanism of action of anti-TNF-α mAbs in the control of inflammatory arthritis.
Pro-atrial natriuretic peptide is a prognostic marker in sepsis, similar to the APACHE II score: an observational study
Authors: Morgenthaler Nils G , Struck Joachim , Christ-Crain Mirjam , Bergmann Andreas , Müller Beat
Published: January 2005

Introduction

Additional biomarkers in sepsis are needed to tackle the challenges of determining prognosis and optimizing selection of high-risk patients for application of therapy. In the present study, conducted in a cohort of medical intensive care unit patients, our aim was to compare the prognostic value of mid-regional pro-atrial natriuretic peptide (ANP) levels with those of other biomarkers and physiological scores.

Methods

Blood samples obtained in a prospective observational study conducted in 101 consecutive critically ill patients admitted to the intensive care unit were analyzed. The prognostic value of pro-ANP levels was compared with that of the Acute Physiology and Chronic Health Evaluation (APACHE) II score and with those of various biomarkers (i.e. C-reactive protein, IL-6 and procalcitonin). Mid-regional pro-ANP was detected in EDTA plasma from all patients using a new sandwich immunoassay.

Results

On admission, 53 patients had sepsis, severe sepsis, or septic shock, and 68 had systemic inflammatory response syndrome. The median pro-ANP value in the survivors was 194 pmol/l (range 20–2000 pmol/l), which was significantly lower than in the nonsurvivors (median 853.0 pmol/l, range 100–2000 pmol/l; P < 0.001). On the day of admission, pro-ANP levels, but not levels of other biomarkers, were significantly higher in surviving than in nonsurviving sepsis patients (P = 0.001). In a receiver operating characteristic curve analysis for the survival of patients with sepsis, the area under the curve (AUC) for pro-ANP was 0.88, which was significantly greater than the AUCs for procalcitonin and C-reactive protein, and similar to the AUC for the APACHE II score.

Conclusion

Pro-ANP appears to be a valuable tool for individual risk assessment in sepsis patients and for stratification of high-risk patients in future intervention trials. Further studies are needed to validate our results.
Microarray-based resequencing of multiple Bacillus anthracisisolates
Authors: Zwick Michael E , Mcafee Farrell , Cutler David J , Read Timothy D , Ravel Jacques , Bowman Gregory R , Galloway Darrell R , Mateczun Alfred
Published: January 2005

We used custom-designed resequencing arrays to generate 3.1 Mb of genomic sequence from a panel of 56 Bacillus anthracis strains. Sequence quality was shown to be very high by replication (discrepancy rate of 7.4 × 10-7) and by comparison to independently generated shotgun sequence (discrepancy rate < 2.5 × 10-6). Population genomics studies of microbial pathogens using rapid resequencing technologies such as resequencing arrays are critical for recognizing newly emerging or genetically engineered strains.
Teaching receptive vocabulary to children with specific language impairment: a curriculum-based approach
Authors: Parsons Stephen , Law James , Gascoigne Marie
Published: January 2005

Children with specific language impairment (SLI) frequently experience difficulties with understanding vocabulary and are subsequently academically disadvantaged. This study describes a curriculum-based assessment and therapy technique and its implementation with two children with language difficulties. Mathematical vocabulary that the children did not understand was randomly allocated to either the treatment or the control conditions. Over a period of seven to eight weeks, two boys were individually taught 18 words each. Each word was taught in one session only. The intervention was found to be effective for both children. The results of this study have implications for the rate of teaching of receptive vocabulary, the role of speech and language therapy in schools and the assessment of receptive vocabulary.
Teaching language organization to a child with pervasive developmental disorder: a case study
Authors: Klecan-Aker Joan S , Gill Cynthia
Published: January 2005

This investigation determined the effects of a treatment programme, The Expression Connection (1991), on the language organization of a firstgrade male child with Pervasive Developmental Disorder (PDD). The methodology consisted of teaching the child story grammar components and the associated syntax requisite of their use. Treatment was conducted twice a week for 12 weeks. Results revealed a significant improvement in the complexity of the child's oral stories. Results with relation to the role of language organization in production of oral narratives and the efficacy of this programme with children with PDD were discussed in comparison to children with specific language impairment.
Issues in the mapping of two diseases
Authors: Dabney Alan R , Wakefield Jon C
Published: January 2005

Recently, there has been increased interest in the geographical modelling of two or more diseases. In this article, we consider a number of issues relating to such an endeavour including the standardization process and the comparison of univariate and bivariate disease mapping models. A principle motivation for the examination of two or more diseases is to discover similarities or dissimilarities in the geographical distribution of risk. In this article, we propose a proportional mortality approach to give clues to areas of similarity and dissimilarity. A secondary aim of bivariate modelling is to ‘borrow strength’ between diseases in order to provide better estimates of risk in each area. We will illustrate various modelling strategies using incidence data from 1996 to 2000 on lung and bladder cancer in Washington state.
On selection and composition in small area and mapping problems
Authors: Longford Nicholas T
Published: January 2005

Maps in which small areas, such as districts, are represented by colours, shades or symbols with sizes determined by the values of estimates are regarded as an indispensable graphical output of analyses concerned with the geographical detail of economic, social, ecological and epidemiological phenomena. The distortion of the distribution of the district specific quantities in such maps, due to misrepresentation of the uncertainty about the estimated values, is discussed, and an alternative based on drawing so-called plausible maps is described. We highlight the pervasive and nonignorable nature of the selection process that identifies the quantity (target) to be estimated. A problem specific to disease mapping is what action, often one of a discrete set, to take in response to the results of an analysis. We argue that the costs (values) associated with correct and incorrect decisions should be integrated in the analysis and, when an analytical treatment is not feasible, plausible scenarios played out by simulations.
A comparison of Bayesian spatial models for disease mapping
Authors: Best Nicky , Richardson Sylvia , Thomson Andrew
Published: January 2005

With the advent of routine health data indexed at a fine geographical resolution, small area disease mapping studies have become an established technique in geographical epidemiology. The specific issues posed by the sparseness of the data and possibility for local spatial dependence belong to a generic class of statistical problems involving an underlying (latent) spatial process of interest corrupted by observational noise. These are naturally formulated within the framework of hierarchical models, and over the past decade, a variety of spatial models have been proposed for the latent level(s) of the hierarchy. In this article, we provide a comprehensive review of the main classes of such models that have been used for disease mapping within a Bayesian estimation paradigm, and report a performance comparison between representative models in these classes, using a set of simulated data to help illustrate their respective properties. We also consider recent extensions to model the joint spatial distribution of multiple disease or health indicators. The aim is to help the reader choose an appropriate structural prior for the second level of the hierarchical model and to discuss issues of sensitivity to this choice.
Untangling the Appraisal-Emotion Connection
Authors: Parkinson Brian
Published: January 2005

This article aims to clarify the nature of the relation between cognitive appraisal and emotion. I distinguish a range of alternative possible hypotheses according to whether this appraisal—emotion connection is assumed to operate at the conceptual or empirical level, whether it is supposed to be a descriptive or causal relation, and whether it is seen as having a contingent or necessary basis. Reviewing the varieties of available evidence for connections at different levels, I find little support for empirical rather than conceptual relations or for necessary as opposed to contingent ones. Ways are suggested in which this evidence might be extended so that more substantive conclusions are possible. I contend that future progress in this research area requires tighter specification of the different kinds of appraisal process that operate during real-time emotional episodes and of their potential interactions with other aspects of the unfolding emotional syndrome. Finally, I develop an alternative perspective on appraisal—emotion relations that views appraisals as representing the message value of interpersonally directed emotions, and I suggest future directions for research based on this approach.
The Psychology of Legitimacy: A Relational Perspective on Voluntary Deference to Authorities
Authors: Tyler Tom R.
Published: January 2005

People within organized groups often internalize their feelings of obligation to obey group rules and the decisions of group authorities. They believe that group authorities and rules are legitimate and, hence, entitled to be obeyed. Because of this belief, group members voluntarily accept and obey rules and decisions from group authorities. This review draws on evidence from studies of authorities in political, legal, managerial, educational, and family settings to explore why people view as legitimate and voluntarily defer to group authorities. Two theories about legitimacy are contrasted: resource-based theories, represented by instrumental models, and identification based theories, represented by the relational model. The findings provide strong support for the existence of a relational component of legitimacy, suggesting that authorities draw an important part of their legitimacy from their social relationship with group members. The findings also show that there is an instrumental component to legitimacy. Hence, the psychology of legitimacy involves both instrumental and relational elements.
Multidimensional Model of Racial Identity: A Reconceptualization of African American Racial Identity
Authors: Sellers Robert M. , Smith Mia A. , Shelton J. Nicole , Rowley Stephanie A.J. , Chavous Tabbye M.
Published: January 2005

Research on African American racial identity has utilized 2 distinct approaches. The mainstream approach has focused on universal properties associated with ethnic and racial identities. In contrast, the underground approach has focused on documenting the qualitative meaning of being African American, with an emphasis on the unique cultural and historical experiences of African Americans. The Multidimensional Model of Racial Identity (MMRI) represents a synthesis of the strengths of these two approaches. The underlying assumptions associated with the model are explored. The model proposes 4 dimensions of African American racial identity: salience, centrality, regard, and ideology. A description of these dimensions is provided along with a discussion of how they interact to influence behavior at the level of the event. We argue that the MMRI has the potential to make contributions to traditional research objectives of both approaches, as well as to provide the impetus to explore new questions.
Social Metacognition: An Expansionist Review
Authors: Jost John T. , Kruglanski Arie W. , Nelson Thomas O.
Published: January 2005

In this article we review recent social psychological contributions to the metacognitive movement. It is argued that social psychologists have long contributed to the study of “thinking about thinking,” even though their work has not yet been recognized as metacognitive. The present “expansionist” survey suggests that the domain of social metacognition should include (a) beliefs about one's own mental states and processes as well as beliefs about those of other people, (b) momentary sensations as well as enduring folk theories, and (c) descriptive beliefs about how the mind works and normative beliefs about how it ought to work. The contents and origins of metacognition are inherently social; at the same time, metacognitions are comprised of cognitive elements and are governed by the principles and laws applicable to human thinking in general. Accordingly, whereas metacognitions about self-knowledge may be derived from different informational sources than metacognitions about other people, the processes whereby different types of metacognitions are formed, activated, and applied are essentially the same. Focusing on the social nature of metacognition and the profound relevance of cultural expectations on cognitive performance makes clear the benefits of systematically exploring the cognitive-social interface in reference to metacognitive phenomena.
A Meta-Analysis of Personality in Scientific and Artistic Creativity
Authors: Feist Gregory J.
Published: January 2005

Theory and research in both personality psychology and creativity share an essential commonality: emphasis on the uniqueness of the individual. Both disciplines also share an emphasis on temporal consistency and have a 50-year history, and yet no quantitative review of the literature on the creative personality has been conducted. The 3 major goals of this article are to present the results of the first meta-analytic review of the literature on personality and creative achievement, to present a conceptual integration of underlying potential psychological mechanisms that personality and creativity have in common, and to show how the topic of creativity has been important to personality psychologists and can be to social psychologists. A common system of personality description was obtained by classifying trait terms or scales onto one of the Five-Factor Model (or Big Five) dimensions: neuroticism, extraversion, openness, agreeableness, and conscientiousness. Effect size was measured using Cohen 's d (Cohen, 1988). Comparisons on personality traits were made on 3 sets of samples: scientists versus nonscientists, more creative versus less creative scientists, and artists versus nonartists. In general, creative people are more open to new experiences, less conventional and less conscientious, more self-confident, self-accepting, driven, ambitious, dominant, hostile, and impulsive. Out of these, the largest effect sizes were on openness, conscientiousness, self-acceptance, hostility, and impulsivity. Further, there appears to be temporal stability of these distinguishing personality dimensions of creative people. Dispositions important to creative behavior are parsed into social, cognitive, motivational, and affective dimensions. Creativity, like most complex behaviors requires an intra- as well as interdisciplinary view and thereby mitigates the historically disciplinocentric attitudes of personality and social psychologists.
Undergraduate Research Experiences in Psychology: A National Study of Courses and Curricula
Authors: Perlman Baron , McCann Lee I.
Published: January 2005

We surveyed departments nationally to better understand the extent of scientific opportunities and experiences for undergraduate psychology students. Results showed intradepartmental variability, but overall students can expect 7 courses that offer research experiences in the typical psychology curriculum. Nonetheless, research is often not the primary course focus; some students must wait until their junior year to take such a course, and most such courses are elective, not required. We discuss implications for departments' curricula and the goals and outcomes for undergraduate education as well as future research directions.
What Makes the Grade? Faculty and Student Perceptions
Authors: Adams Jeffrey B.
Published: January 2005

This study extended the work of White and Dunlap (1999) by quantifying faculty views regarding the relative effects performance and effort should have on final grades and by comparing faculty views with student views to assess their similarity. Survey results of 159 students and 59 faculty indicated that students believed effort should influence grades significantly more than did faculty. Differences existed when measuring performance and effort as (a) a percentage of a final course grade and (b) letter grades assigned in different course types. In addition, faculty and students differed significantly in the number of hours they designated as defining superior effort. Discussion of results considers the potential impact discrepancies can have on faculty and student relations, student learning, and student evaluation of teaching.
Novel approaches to miniature flight platforms
Authors: Michelson R C
Published: January 2005

No other air vehicle design space has presented the mix of challenges as that of miniature flight platforms. By definition, these tiny platforms are unmanned and endeavor to invade the flight regime of birds and insects. In order to do so, the creators of these aerial robots must address the same physical design constraints that have already been mastered by the world of airborne biology, including low Reynolds number aerodynamics, high energy density and extreme miniaturization. This paper focuses on the high degree of innovation required to make practical miniaturized flying machines on the scale of small birds and insects.
The T-wing tail-sitter unmanned air vehicle: From design concept to research flight vehicle
Authors: Stone R H
Published: January 2005

This paper considers the key aspects of the development of the T-Wing tail-sitter unmanned air vehicle (UAV), starting from a novel concept through to the current flight test vehicle. The T-Wing is a twin-engine UAV that relies on propeller wash over its elevons and rudders for control during low-speed vertical flight but performs the majority of its mission in wing-borne horizontal flight. The foundation for the successful development of the T-Wing to date is the integrated aerodynamic and propulsion analysis of the wing-propeller interaction. This is critical for the vehicle' vertical flight controllability and feeds directly into other key areas of the overall development process, including the use of multi-disciplinary optimization for preliminary vehicle design and the development of an extensive six-degree-of-freedom non-linear simulation of the vehicle to aid in control system design. This paper also presents some of the testing that has been used to support the analysis. This has allowed the T-Wing to progress from a paper concept to a flying research UAV.
An overview of insect-inspired guidance for application in ground and airborne platforms
Authors: Srinivasan M V , Zhang S W , Chahl J S , Stange G , Garratt M
Published: January 2005

Flying insects provide a clear demonstration that living organisms can display surprisingly competent mechanisms of guidance and navigation, despite possessing relatively small brains and simple nervous systems. Consequently, they are proving to be excellent organisms in which to investigate how visual information is exploited to guide locomotion and navigation. Four illustrative examples are described here, in the context of navigation to a destination. Bees negotiate narrow gaps by balancing the speeds of the images in the two eyes. Flight speed is regulated by holding constant the average image velocity as seen by the two eyes. This automatically ensures that flight speed is reduced to a safe level when the passage narrows. Smooth landings on a horizontal surface are achieved by holding image velocity constant as the surface is approached, thus automatically ensuring that flight speed is close to zero at touchdown. Roll and pitch are stabilized by balancing the signals registered by three visual organs, the ocelli, that view the horizon in the left, right and forward directions respectively. Tests of the feasibility of these navigational strategies, by implementation in robots, are described.
Study on pure squeeze elastohydrodynamic lubrication motion using optical interferometry and the inverse approach
Authors: Chu H-M , Lee R-T , Chiou Y-C
Published: January 2005

This paper uses an optical elastohydrodynamic lubrication (EHL) impact tester to explore the effects of squeeze velocity, load, and lubricant viscosity on the dimple film thickness occurring when a ball impacts a flat plate covered by a thin layer of oil. Three types of motion for the ball are combined and simulated in this experiment to find important operation parameters. In the direct numerical solution, hydrodynamic lubrication is assumed at the initial impact stage and EHL is assumed at the high-pressure stage. Pressure and dimple shapes are obtained by numerical solution of the coupled transient Reynolds equation, elasticity equation, and ball motion equation. The inverse approach is proposed to estimate pressure and apparent viscosity in pure squeeze EHL motion. Results show that, with higher impact speeds and loads, more time is needed to reach stability. Also with lower viscosities, more time is needed to reach stability. Increasing the squeeze speed, load, and viscosity all make the dimple deeper. The post-impact high-pressure condition for the constant-load case is suitable for evaluating the pressure-viscosity index. The inverse approach is successfully used to estimate the pressure distribution resulting from the film thickness map obtained by interferometry. Agreement between the experimental value of the test fluid and the estimated value is quite good.
Stiffness and damping characteristics of lubricated ball bearings considering the surface roughness effect. Part 2: Numerical results and application
Authors: Sarangi M , Majumdar B C , Sekhar A S
Published: January 2005

A numerical solution for the stiffness and damping characteristics of an isothermal, elastohydrodynamically lubricated point contact is presented considering the surface roughness effect and variation in viscosity with pressure. An attempt has been made to derive empirical formulae for the calculation of stiffness and damping coefficients of lubricated point contacts with a non-linear least-squares curve-fitting technique using different numerically evaluated data, thereby avoiding time-consuming numerical calculations. From this the overall stiffness and damping matrices of the ball bearing are obtained with a proper load distribution. A comparative study on the dynamics of a rotor-bearing system is carried out for a dry contact ball bearing, a lubricated contact ball bearing and a plain journal bearing.
Friction behaviour of plasma-sprayed stainless steel coatings doped with graphite particles
Authors: Harir A , Fournier P , Platon F , Fourcade P
Published: January 2005

The objective of this study is to achieve, by atmospheric plasma spraying (APS) on aluminium alloy substrates, a coating exhibiting a higher superficial hardness and an improved tribological behaviour in dry friction compared with that of the aluminium alloy. A new process has been developed to incorporate graphite particles in a stainless steel coating during its formation.

A special injection system has been developed to deposit graphite particles (2–12 μm in diameter) at the surface close to the spot sprayed with stainless steel in order to incorporate them within the forming coating. Tribological tests have been carried out on a pin-on-disc tribometer. The friction coefficient evolution of this composite coating is compared with that of commonly used stainless steel coatings. Tribological behaviour has been characterized for different test conditions. The dry friction coefficient of this coating against a 100C6 steel pin is reduced by a factor of between 1.5 and 4 compared with that obtained with plasma-sprayed stainless steel, depending on the experimental conditions.
Influence of carbon coatings on lubricating properties of boundary layers
Authors: Levchenko V , Matveenko V , Buyanovsky I , Ignatieva Z
Published: January 2005

The friction behaviours of two types of diamond-like carbon coating (amorphous and monocrystalline) were studied under boundary lubrication. As lubricants, liquid paraffin with and without surfactant additives (stearic and oleic acids) were used as well as base mineral oil with viscosity corresponding to SAE 30. Tests were conducted on a ball-on-disc tribometer and on a tribometer where two rings were rubbing against each other. It was found that in all types of test the monocrystalline coating ensures minimal values of friction coefficient in a wider range of temperatures, whereas the amorphous coating has maximum values of friction coefficient compared with the monocrystalline coating and with the reference uncoated steel pair. This effect takes place for all lubricants studied. The observed experimental data can be explained by the strong orienting effect of the monocrystalline carbon coating on the structural order of molecules in boundary layers and correspondingly on their lubricating ability. The effect of the amorphous coating on molecular orientation in boundary layers is rather poor.
An engineering approach on sliding friction in full-film, heavily loaded lubricated contacts
Authors: Morales-Espejel G E , Wemekamp A W
Published: January 2005

Various schemes to approximate the sliding friction coefficient in heavily loaded lubricated contacts with different rheologies are studied. Rather than using complex full numerical thermo-hydrodynamically lubricated solutions to calculate the friction coefficient, in this paper the emphasis is on rather simplified approaches which are suitable for providing the user with physical insight of the phenomenon and at the same time fulfilling the most advanced engineering applications.

The simplification of the equation for the lubricant velocity distribution for an assumed Hertzian contact with a fixed parallel film thickness and different fluid rheologies leads to simple solutions with comparable results to the recently obtained (through full numerical simulations) friction master curves from Jacod.

Point-by-point models with thermal effects are included using the simplified model for the oil and wall temperature calculation from Olver and Spikes. The results are compared with full numerical solutions from literature and good agreement is found. A one-dimensional scheme is extended to a two-dimensional model where the integration of the varying viscosity with pressure and temperature is included. The wall surface temperature calculation is then carried out using a fast Fourier transform convolution approach.
Investigation of short‐period gravity waves with the Lindenberg 482 MHz tropospheric wind profiler
Authors: Böhme T. , Hauf T. , Lehmann V.
Published: January 2005

During four consecutive days in May 2001, convectively forced short‐period (6–45 min) gravity waves were observed with a 482 MHz wind profiler, which is continuously operated by the Deutscher Wetterdienst (German Weather Service) at the Lindenberg observatory, 60 km south‐east of Berlin. The objective of this campaign was to investigate onset and development of convectively forced gravity waves in the lower and middle troposphere. The wave character could be unambiguously identified by simultaneous vertical wind and temperature measurements and their respective phase shift of π/2. In accordance with previous findings, convection waves were found to be generated at the top of the convective boundary layer. They propagate predominantly horizontally with a slow but clearly recognizable vertical increase of wave activity. The layer with significant wave activity reached the upper detection range at 7.0 km within a couple of hours on each of the observational days. Gravity wave activity started to decay after 16 UTC with a slower rate than the simultaneously decaying forcing convection. Some wave activity remained during the night but at low amplitude levels. The vertical wind energy component of the free atmosphere was found to be about 30% of the corresponding convective boundary layer (CBL) energy, which is much more than previously reported values from numerical simulations. The wavelet analysis of highly resolved wind profiler vertical velocity data (Δt = 16 s, Δz = 250 m) in the boundary layer and free troposphere gives new insights into the temporal and vertical development of very‐short‐period convection waves through the troposphere. At the CBL top, a broad spectrum of wave scales with intrinsic periods between 6 and 45 min is generated. With increasing height, shorter scales (T ≤ 13 min) disappear and only longer ones remain. Wave trapping, which is confirmed by vertically orientated phase lines, is an important mechanism here. Copyright © 2004 Royal Meteorological Society
Boundary‐layer variations due to orographic‐wave breaking in the presence of rotation
Authors: Grisogono B. , Enger L.
Published: January 2005

A mesoscale numerical model is used to study the atmospheric boundary‐layer (ABL) response to nonlinear orographic forcing with Coriolis effect, f, over a mountain with length (the cross‐wind component) comparable to the Rossby radius of deformation, LR. The orographic‐wave breaking occurring for Froude number Fr<1, affected by f>0, intensifies on the northern flank for westerly flows, as also found in other recent studies. A cumulative effect occurs as the Coriolis force lifts the northern ABL top and generates a stronger low‐level jet (LLJ) than on the southern side. A differential layering also appears, since the specific humidity is higher in the lower southern ABL than in the related northern ABL, and vice versa. By contrast, there are higher values of the turbulent kinetic energy and humidity in the upper northern ABL.

The breaking of flow symmetry around the orography due to f changes both the vertical vorticity and horizontal divergence field, (ζ, D), it modulates eddies and turbulence leading to the differential layering of the ABL. The stronger northern LLJ and its weaker southern counterpart, both meandering, together with the asymmetric wave breaking, induce strong lee‐side fluctuations of the (ζ, D) field in the presence of f. The enhanced (ζ, D) production due to wave breaking over the distance ≈ LR, the primary atmosphere–orography resonance occurs mainly in the vertical, while the ‘f‐enhancement’ occurs in the horizontal plane. In this way, the initial mesoscale forcing may extend its effects over the synoptic scale. Copyright © 2004 Royal Meteorological Society
Ozone assimilation in the ERA‐40 reanalysis project
Authors: Dethof A. , Hólm E. V.
Published: January 2005

In this paper we outline the ozone model and analysis system used in the ECMWF 45‐year reanalysis project, and take a first look at the quality of the resulting ozone fields. The analysed ozone, both profiles and total‐column ozone field, generally compares well with independent observations. However, there are certain problematic situations when the profile is not correct even if the analysed total ozone is close to observations. These situations appear when there is a bias between the model and the observations used in the assimilation. Suggestions are made for improvements of the ozone assimilation and modelling, including the introduction of a bias correction scheme for ozone data. Copyright © 2004 Royal Meteorological Society
A cold‐air cyclogenesis study using a potential vorticity inversion method
Authors: Lambert Dominique , Arbogast Philippe , Cammas Jean‐Pierre , Donnadille Jérôme , Mascart Patrick
Published: January 2005

A cold‐air cyclogenesis is studied using a potential vorticity (PV) inversion method. In this study, the method is coupled with the French spectral operational model ARPEGE which is initialized by four‐dimensional variational reanalyses. Sensitivity studies are performed for Intensive Observation Period 18 (IOP18) (low 44, 19–24 February 1997) of the Fronts and Atlantic Storm‐Track EXperiment (FASTEX). This event is one of the Type C cyclogeneses recently identified in the FASTEX dataset. The triggering role of a coherent tropopause disturbance on the cyclogenesis is discussed by comparing a reference forecast and a simulation in which the tropopause coherent structure is removed. Interactions between the atmospheric upper level and the cyclogenesis are found significant. A second important factor is the influence of the surface temperature. Evaluations of vertical motions for different surface temperature distributions show that the warmer the sea surface, the deeper the low. The location of the low with respect to the ice‐shelf limit is also an important factor. Copyright © 2004 Royal Meteorological Society
The ECMWF reanalysis of the MAP Special Observing Period
Authors: Keil Christian , Cardinali Carla
Published: January 2005

A reanalysis of the Mesoscale Alpine Programme (MAP) Special Observing Period (7 September to 15 November 1999) was performed at the European Centre for Medium‐Range Weather Forecasts (ECMWF). Substantial upgrades in the global data assimilation system 4D‐Var (T511/159L60, horizontal resolution approximately 40 km) combined with special MAP observations provide a new reference description for studies on mountain‐related atmospheric phenomena. The MAP observations used in the MAP reanalysis comprise European windprofilers, high‐resolution radiosondes and surface observations. The assimilation of MAP observations results in a slight weakening of the cyclonic flow over central Europe and of the mid‐tropospheric westerly wind over the Alpine region. Also, MAP observations lead to moister conditions in the southern Alpine region, southern France and over the Adriatic Sea. The comparison of forecast daily rainfall from the MAP reanalysis with observed precipitation totals averaged over the Po catchment shows good agreement in timing and rain amount. Investigations of some Intensive Observation Periods (IOPs) illustrate specific aspects of the MAP reanalysis. Different precipitation patterns characteristic of different flow regimes are well captured (IOP2b and IOP8). The assimilation of windprofilers rectifies the divergent wind field, but changes can erroneously feed back on the humidity field (IOP2a) because of the way the humidity analysis is performed (a modified humidity analysis was introduced at ECMWF in 2003). Validation with model‐independent Global Positioning System (GPS) derived integrated water‐vapour contents shows that the humidity field describes well the inter‐diurnal humidity variations at southern Alpine GPS stations. However, the reanalysis appears to be slightly too dry compared with GPS measurements. Copyright © 2004 Royal Meteorological Society
Orographic flow‐blocking scheme characteristics
Authors: Brown A. R. , Webster S.
Published: January 2005

The characteristics of the orographic flow blocking parametrization used in the Met Office Unified Model are examined in a one‐dimensional framework. This approach allows feedback of the parametrized stresses on the winds resulting, in some cases, in stresses very different from those that would be obtained without this feedback. The key controlling non‐dimensional parameters are identified, and the implications of the results for the use of the scheme in climate and numerical weather‐prediction models are discussed. Copyright © 2004 Royal Meteorological Society
The flow of energy through the earth's climate system
Authors: Trenberth Kevin E. , Stepaniak David P.
Published: January 2005

The primary driver of the climate system is the uneven distribution of incoming and outgoing radiation on earth. The incoming radiant energy is transformed into various forms (internal heat, potential energy, latent energy, and kinetic energy), moved around in various ways primarily by the atmosphere and oceans, stored and sequestered in the ocean, land, and ice components of the climate system, and ultimately radiated back to space as infrared radiation. The requirement for an equilibrium climate mandates a balance between the incoming and outgoing radiation, and further mandates that the flows of energy are systematic. These drive the weather systems in the atmosphere, currents in the ocean, and fundamentally determine the climate. Values are provided for the seasonal uptake and release of heat by the oceans that substantially moderate the climate in maritime regions. In the atmosphere, the poleward transports are brought about mainly by large‐scale overturning, including the Hadley circulation in low latitudes, and baroclinic storms in the extratropics, but the seamless nature of the transports on about monthly time‐scales indicates a fundamental link between the two rather different mechanisms. The flows of energy can be perturbed, causing climate change. This article provides an overview of the flows of energy, its transformations, transports, uptake, storage and release, and the processes involved. The focus is on the region 60°N to 60°S, and results are presented for the solstitial seasons and their differences to highlight the annual cycle. Challenges in better determining the surface heat balance and its changes with time are discussed. Copyright © 2004 Royal Meteorological Society
Studies of the Sorption of Palladium(II) Ions from Model Chloride Systems onto an Ion Exchanger Containing Isothiourea Groups and onto Weakly Basic Anion Exchangers of Various Types
Authors: Hubicki Z. , Leszczyńska M.
Published: January 2005

The separation and determination of precious metals in minerals, alloys and environmental samples is very difficult due to their low concentration under natural circumstances. However, despite such difficulties, there has been a rapid development of chromatographic separation methods for noble metal ions. In the present work, laboratory studies of the selective removal of palladium(II) ions from 0.1–6.0 M HCl, 0.1–0.9 M HCl/0.9–0.1 M HNO3, 1.0 M AlCl3-0.1 M HCl and 1.0 M ZnCl2-0.1 M HCl onto various types of ion exchangers have been undertaken. In this context, the applicability of the selective ion exchanger Purolite S-920 and of the weakly basic anion exchangers Amberlyst A-21, Amberlite IRA-67 and Amberlite IRA-93 were examined. The sorption of Pd(II) ions was undertaken by both dynamic and static methods. The working ion-exchange capacities as well as the weight and bed distribution coefficients were calculated from the breakthrough curves for Pd(II) ions. The selective ion exchanger Purolite S-920 exhibited the highest value for the working ion-exchange capacity of Pd(II) ions.
Response Spectrum Method for Nonlinear Surface Ground Analysis
Authors: Takewaki Izuru
Published: January 2005

An equivalent linear response spectrum approach is proposed for nonlinear surface ground analysis. In contrast to the conventional method which deals with only a single ground motion for equivalent linearization of soil properties, it is argued in this paper that a design response spectrum defined at the upper level (bottom of the surface ground) of an engineering bedrock can be handled as the target design earthquake. The effective shear strain in each soil layer is evaluated by means of a response spectrum method in which the mean peak shear strain is computed by a response spectrum mode-superposition procedure. The soil hysteretic damping is substituted by the corresponding viscous damping. The stiffness coefficient and damping ratio of each soil layer are obtained iteratively from the nonlinear relation of stiffness reduction factors and damping ratios with respect to the strain level. After the evaluation of the equivalent stiffness coefficient and damping ratio of every soil layer, the surface ground response can be described via the one-dimensional wave propagation theory. The reliability and accuracy of the proposed analysis method is examined through comparison with the results obtained by the conventional method (represented by the SHAKE program) for many simulated spectrum-compatible ground motions.