bluuebunny/crossref_metadata_2025 huggingface dataset:
Intramatrix events during cryopreservation of porcine articular cartilage using rapid cooling
Authors: Jomha N. M. , Anoop P. C. , McGann L. E.
Published: August 2003

Cryopreservation of articular cartilage may improve long‐term transplantation results if cell and matrix integrity can be maintained. This study examined intramatrix events in intact porcine articular cartilage that occurred during a rapid‐cooling technique with various concentrations of dimethyl sulfoxide (DMSO) (1, 3, 5, 6 and 7 M). Thermocouples were inserted into the solution and in the cartilage matrix to record the temperature during rapid cooling. In addition, scanning electron microscopy of freeze‐substituted samples was performed and quantitatively evaluated for the areas representing ice in the matrix. The results of this study showed that low concentrations of DMSO resulted in the largest temperature gradient between the matrix and the surrounding solution, which occurred near the freezing point of the cryoprotectant solution. At higher concentrations of DMSO, the peak temperature gradient occurred near the glass transition temperature. The temperature measurements suggested that a significant amount of ice formed within the matrix at lower DMSO concentrations. At higher DMSO concentrations that resulted in vitrification of the external solution, there was evidence of some ice in the matrix. The scanning electron micrographs demonstrated significantly more matrix disruption (likely due to ice formation) (P < 0.02) in the lower DMSO concentrations (1 and 5 M) while the 6 M DMSO concentration demonstrated minimal matrix disruption. Cryopreservation of articular cartilage with a rapid‐cooling technique and high concentrations of DMSO resulted in partial vitrification of the matrix and significantly less matrix disruption. It appears that successful cryopreservation of viability and function in articular cartilage will require high concentrations of cryoprotectants and rapid cooling. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
A biomechanical study of lumbar spondylolysis based on a three‐dimensional finite element method
Authors: Chosa Etsuo , Totoribe Koji , Tajima Naoya
Published: August 2003

Biomechanical analyses under compression only, and for a combination of flexion, extension, rotation, and lateral bending were performed to evaluate the stress of the interarticular portion of the lumbar vertebra using a nonlinear three‐dimensional finite element method. A detailed three‐dimensional L4–L5 motion segment model was developed that took into consideration the material nonlinearities of ligaments and annular fibers and the contact nonlinearities of facet joints. For a more accurate examination, the separation of cortical bone and cancellous bone for both posterior and anterior elements were also considered. The stress in the pars interarticularis was weakest under compression alone, but stronger under compression with lateral bending loading, with flexion, with rotation, and with extension. Under each loading condition, the region of the stress concentration was consistent with the separated region of the spondylolysis observed in clinical situations. Since the stress in the pars interarticularis was high under extension and rotation in particular, those loadings were suggested to be relatively high risk factors leading to spondylolysis. © 2003 Published by Elsevier Ltd. on behalf of Orthopaedic Research Society.
Inflammation and changes in cytokine levels in neurological feline infectious peritonitis
Authors: Foley JE , Rand C. , Leutenegger C.
Published: August 2003

Feline infectious peritonitis (FIP) is a progressive, fatal, predominantly Arthus-type immune-mediated disease that is triggered when cats are infected with a mutant enteric coronavirus. The disease presents variably with multiple organ failure, seizures, generalized effusion, or shock. Neurological FIP is clinically and pathologically more homogeneous than systemic ‘wet’ or ‘dry’ FIP; thus, comparison of cytokine profiles from cats with neurological FIP, wet FIP, and non-FIP neurological disease may provide insight into some baseline characteristics relating to the immunopathogenesis of neurological FIP. This study characterizes inflammation and changes in cytokines in the brain tissue of FIP-affected cats. Cellular infiltrates in cats with FIP included lymphocytes, plasma cells, neutrophils, macrophages, and eosinophils. IL-1β, IL-6, IL-12, IL-18, TNF-α, macrophage inhibitory protein (MIP)-1α, and RANTES showed no upregulation in the brains of control cats, moderate upregulation in neurological FIP cats, and very high upregulation in generalized FIP cats. Transcription of IFN-γ appeared upregulated in cats with systemic FIP and slightly downregulated in neurological FIP. In most cytokines tested, variance was extremely high in generalized FIP and much less in neurological FIP. Principal components analysis was performed in order to find the least number of ‘components’ that would summarize the cytokine profiles in cats with neurological FIP. A large component of the variance (91.7%) was accounted for by levels of IL-6, MIP-1α, and RANTES. These findings provide new insight into the immunopathogenesis of FIP and suggest targets for immune therapy of this disease.
Ischemic neuromyopathy due to peripheral arterial embolization of an adenocarcinoma in a cat
Authors: Sykes J.E.
Published: August 2003

A case of peripheral arterial tumor embolization in a cat is described. The cat presented with signs of aortic thromboembolism, including decreased peripheral pulse quality, pallor, and coolness of the distal limbs, as well as proprioceptive deficits. Thoracic radiographs revealed a cavitary lung mass; echocardiography was unremarkable. Cytologic evaluation of aspirates of the mass suggested malignancy. The left hindlimb was amputated, and histopathology confirmed embolization of an adenocarcinoma. Although rare, peripheral arterial tumor embolization should be considered as a differential in cats presenting with signs of thromboembolic disease.
A solid mature teratoma of a feline ovary
Authors: Sato T , Hontake S , Shibuya H , Shirai W. , Yamaguchi T.
Published: August 2003

A 17-year-old female crossbred cat developed a mass on the left ovary. The mass was solid, firm, 5.5×3.5×4.5 cm. The mass contained ectodermal components (skin and appendages), mesodermal components (osseous, cartilaginous and adipose structures), and endodermal components (glandular structures lined by columnar epithelium). The tumor was diagnosed as a solid, mature teratoma of the ovary.
Prevalence of polycystic kidney disease in Persian and Persian related cats in France
Authors: Barthez PY , Rivier P , Begon D
Published: August 2003

The prevalence of polycystic kidney disease (PKD) has been estimated in the USA, Australia, UK, and Germany, but no data are available to date in France. The purpose of this study was to determine prevalence of PKD in Persian and Persian related breeds of cats in France. Medical records of all healthy cats presented for ultrasonographic screening of PKD between December 2000 and April 2002 were analysed from two centres (ENVL and ENVA). Cats were classified as positive when at least one anechoic cavity was found in at least one kidney. Prevalence of PKD was compared between the two screening centres, between different breeds evaluated, and between male and female using Chi-square test. A total of 310 cats were examined, including 92 at ENVL (57 Persians, 22 Exotic Shorthairs, 7 Chartreux, 4 Norwegian Forest Cats, and 2 Abyssins) and 218 at ENVA (163 Persians, 42 Exotic Shorthairs, 4 Chartreux, 4 British Shorthairs, 2 American Whirehairs, 2 Norwegian Forest Cats, and 1 American Shorthair). Prevalence of PKD was 41.8% in Persian cats and 39.1% in Exotic Shorthair. No PKD was detected in cats from other breeds. There was no significant difference between prevalence of PKD found in ENVL and ENVA, between prevalence of PKD in Persians and in Exotic Shorthairs, and prevalence of PKD in male and in female. Prevalence of PKD in Persians and Exotic Shorthair cats in France is currently high but is similar to prevalence in other parts of the world. Selection based on ultrasonographic detection of cysts should decrease prevalence of PKD in the future.
Too Spineless to Rebel? New Labour's Women MPs
Authors: COWLEY PHILIP , CHILDS SARAH
Published: August 2003

The 1997 British general election saw a record 120 women returned to the House of Commons, 101 of them Labour. Yet if the most striking feature of the 1997 intake into the House of Commons was the number of newly elected women, then the most striking feature of the backbench rebellions in that parliament was the lack of these women amongst the ranks of the rebels. They were less than half as likely to rebel against the party whip as the rest of the Parliamentary Labour Party; even those who did, did so around half as often. Attempts to explain this difference fall into two broad groups: (i) those that attempt to explain the difference away, as resulting from other characteristics of the women, and (ii) those that attempt to explain it – indeed, celebrate it – as evidence of a different, women's, style of political behaviour. Attempts at (i) are largely unconvincing: most of the supposed explanations for the difference do not stand up to empirical verification. Although difficult to prove, a belief in (ii) is dominant amongst the new women themselves.
Redistributive Politics and Stock Price Dispersion
Authors: McGILLIVRAY FIONA
Published: August 2003

Cross-sectional time-series data from fourteen stock markets, from 1973 to 1996, are used to study how political institutions compare in affecting party governments' incentives to enrich one group of industries at the expense of another. Using measures of cross-sectoral variance of price changes within stock markets as a proxy for change in redistributive policy, I show that political change is important in both proportional representation (PR) and majoritarian systems. As parties shift in and out of government, trade and industrial policy is redistributed to favour the parties' industrial supporters. Such changes in policy increase the cross-sectoral dispersion in price changes, with newly advantaged industries seeing their stock increase, while the price of those losing favourable policy declines. The temporal impact of redistribution differs across electoral systems, with the impact of political change being more immediate in majoritarian systems and the effect being more diffuse in PR systems. Majoritarian systems are also more responsive to economic shocks, while changes in economic conditions have few discernable effects on the dispersion of stock prices in PR countries. PR systems, however, experience overall higher levels of dispersion. I contrast these results with the dominant extant arguments of radical policy shifts in majoritarian systems and policy stability in PR systems.
Election Timing in Majoritarian Parliaments
Authors: SMITH ALASTAIR
Published: August 2003

I propose and test an informational theory of endogenous election timing. I assume leaders have more accurate estimates of future outcomes than citizens. The prospect of declining future performance spurs leaders to call early elections. Since leaders condition their timing decisions on their expectations of future performance, early elections signal a leader's lack of confidence in future outcomes. The earlier elections occur, relative to expectations, the stronger the signal of demise. Using data on British parliaments since 1945, I test hypotheses relating the timing of elections, electoral support and subsequent economic performance. As predicted, leaders who call elections early, relative to expectations, experience a decline in their popular support relative to pre-announcement levels.
How Elections Change the Way Citizens View the Political System: Campaigns, Media Effects and Electoral Outcomes in Comparative Perspective
Authors: BANDUCCI SUSAN A. , KARP JEFFREY A.
Published: August 2003

Attitudes towards the political system have often been assumed to be stable attributes that are not easily influenced by short-term forces. We examine the extent to which attention to media coverage, campaign activity and electoral outcomes can mobilize support for the political system in the context of an election campaign. Using pre-election and post-election survey panels from the United States, Britain and New Zealand, we find only small shifts in aggregate measures of system support. However, we find that there are significant shifts in system support at the individual level that can be explained by status as election winners, attention to the media, particularly serious news coverage and economic perceptions. The results have implications for the debate over measures of system support such as trust, cynicism and efficacy.
Non-Electoral Responsiveness Mechanisms: Evidence from the Asian Less Democratic Newly Industrializing Countries
Authors: YAP O. FIONA
Published: August 2003

Does the lack of competitive elections in the less democratic newly industrialized or industrializing countries (NICs) mean that their governments are unconstrained by their citizens' preferences for economic performance? In this article, I show how non-electoral mechanisms in the less democratic NICs of South Korea, Singapore and Malaysia constrain their governments. Governments pay attention to the effects of policies on economic performance because labour disquiet and disinvestment are likely to arise otherwise. To pre-empt labour disquiet and disinvestment, the governments offer ‘credible apologies’ that include punishment and monitoring of government when economic performance is less than optimal in these countries. When they fail to offer credible apologies, labour and producers respond with strikes and disinvestment. Governments' credible apologies play an important role in explaining labour quiescence and production investment. The argument and evidence contrasts with the general impression that governments in the less democratic NICs are constrained only by elites or are responsible only to themselves. The analysis shows that governments use bargaining mechanisms even where the citizens are perceived as meek and without bargaining strength.
Influence of pasture and concentrates in the diet of grazing dairy cows on the fatty acid composition of milk
Authors: Stockdale C Richard , Walker Glen P , Wales William J , Dalley Dawn E , Birkett Anne , Shen Zhiping , Doyle Peter T
Published: August 2003

In five short-term experiments conducted in Victoria in 1997 and 1998, grazing dairy cows were given either pasture alone or pasture supplemented with high-energy concentrates, and the fatty acid profiles of milk fat were measured. We established the effects of these feeds on some aspects of milk fat of importance for human nutrition, but we specifically focused on the hypothesis that conjugated linoleic acid (CLA) concentrations in milk fat increase as pasture intake increases, and decrease as more concentrates are fed. In agreement with previous research, feeding fresh pasture alone resulted in high concentrations (1·0–1·8 g/100 g milk fat) of CLA. When the effect of level of pasture consumption on CLA content was examined, a significant positive relationship (r2=0·35; P<0·05) was obtained. When cereal grain concentrates were used to supplement pasture intake, the CLA content of milk fat generally declined (P<0·05), except where the amount of concentrates given led to a marked reduction in total milk fat concentration. The use of cereal grain concentrates also generally resulted in significant (P<0·05) increases in medium-chain saturated fatty acids, but always reduced the contribution of butyric acid to milk fat, from 4·5 to 3·9 g/100 g milk fat, on average.
The effect of morphine and naloxone on the release of prolactin during machine milking in dairy cows
Authors: Tančin Vladimír , Schams Dieter , Kraetzl Wolf-Dieter
Published: August 2003

The aim of the study was to determine the role of opioids modulating the release of prolactin (PRL) in response to milking in sixteen Brown-Swiss dairy cows. Two experiments were carried out to measure the dose-related effect of morphine and the effect of the opioid antagonist naloxone (NAL), with or without morphine. In the first experiment, six cows were injected (via catheter) on 3 consecutive days after the control milking (0 mg) with 21, 70 and 210 mg morphine-HCl 10 min before the start of the morning milking. The second experiment was divided into two parts. In the first part, four cows were injected after control morning milking with 210 mg morphine, 10 min before the start of the following morning milking. This was followed on the next day by an application of 210 mg NAL (15 min before the start of milking) and 210 mg morphine. In the second part, after control milking for 1 d, six cows were injected with 210 mg NAL 10 min before milking. Morphine at the highest dose tended to stimulate basal PRL levels in the first and second experiments (P<0·10). PRL increased in response to machine milking but morphine did not stimulate its release further. NAL alone, or when given with morphine did not influence the release of PRL in response to machine milking. However, NAL was effective in suppressing the increase in basal levels of PRL caused by morphine. In conclusion, although morphine tended to stimulate basal levels of PRL before milking, the release of PRL during milking seemed not to be regulated by opioids.
Effect of cereal grain and fibre supplements on the fatty acid composition of milk fat of grazing dairy cows in early lactation
Authors: Wijesundera Chakra , Shen Zhiping , Wales William J , Dalley Dawn E
Published: August 2003

Two experiments were undertaken to determine the effects of cereal grain and fibre (hay or straw) supplements on the fatty acid composition of milk fat of grazing dairy cows in early lactation. In both experiments, grain supplements significantly increased (P<0·05) the proportion of the endogenously synthesized 10[ratio ]0–16[ratio ]0 fatty acids. Of the C18 acids, the proportion of 18[ratio ]0 and 18[ratio ]3 was significantly decreased (P<0·05) by grain supplementation, while that of 18[ratio ]2 was significantly increased (P<0·05). Irrespective of diet, 18[ratio ]1 trans-11 was the most dominant trans 18[ratio ]1 isomer in milk fat. In the first experiment, the proportions of the 18[ratio ]1 trans-11 isomer and conjugated linoleic acid (CLA, 18[ratio ]2 cis-9, trans-11) were highest for the pasture-only diets, and significantly (P<0·05) decreased with grain supplementation. The opposite result was observed in the second experiment, conducted in a different dairy region, suggesting that factors such as the quality of pasture on offer and the physiological state of the cow could affect the content of CLA and trans fatty acids in milk fat. In both experiments, there was a significant positive linear relationship between CLA and 18[ratio ]1 trans-11. Fibre supplements had little effect on the fatty acid composition of the milk.
Synthesis of ethyl butanoate by a commercial lipase in aqueous media under conditions relevant to cheese ripening
Authors: Liu Shao-Quan , Holland Ross , Crow Vaughan
Published: August 2003

A fruity flavour note is traditionally regarded as a defect in cheese varieties such as Cheddar (Bills et al. 1965; McGugan et al. 1975; Horwood et al. 1987). However, fruitiness is an attribute of other cheese varieties such as Parmesan and Parmigiano Reggiano (Dumont et al. 1974; Meinhart & Schreier, 1986). It is well accepted that esters such as ethyl butanoate and ethyl hexanoate cause the fruity flavour described as apple-like or pineapple-like in raw milk and cheeses (Bills et al. 1965; Engels et al. 1997; Friedrich & Acree, 1998). The development of fruity flavour is often attributed to the esterification of free fatty acids and ethanol by esterases from lactic acid bacteria and psychrotrophic pseudomonads (Hosono et al. 1974; Morgan, 1976).
High pressure homogenisation of milk (b) effects on indigenous enzymatic activity
Authors: Hayes Maurice G , Kelly Alan L
Published: August 2003

The objective of this study was to determine the effect of high pressure homogenisation (HPH) on alkaline phosphatase activity and plasmin and plasminogen-derived activities in raw whole bovine milk. Milk (approximately 4% fat) was treated by two-stage conventional homogenisation (18 MPa) or single or two-stage HPH at 50, 100, 150 or 200 MPa. Inactivation of plasmin and plasminogen-derived activities was evident in conventionally homogenised samples, and increased as HPH pressure increased. Two-stage HPH reduced both activities to a greater extent than single-stage HPH. Milk inlet temperature had a significant effect on residual plasmin and plasminogen activities of HPH-treated milk samples, especially those treated at 50 MPa. Inactivation of plasmin and plasminogen on HPH-treatment (150 MPa) of milk samples of varying fat contents (0–10%) was also investigated; there was a curvilinear relationship between residual plasmin and plasminogen-derived activities and fat content in the ranges 0–2% and 0–4%, respectively, with little additional inactivation at higher fat contents. Thus, indigenous proteolytic activity of milk is clearly affected by HPH. However, all homogenised milk samples retained active alkaline phosphatase, indicating that thermal conditions during HPH did not equate to that of conventional high temperature short time pasteurisation, and that the wide range of forces experienced by milk during HPH treatment does not inactivate the latter enzyme.
High pressure homogenisation of raw whole bovine milk (a) effects on fat globule size and other properties
Authors: Hayes Maurice G , Kelly Alan L
Published: August 2003

Although widely adopted by the chemical and pharmaceutical industries in recent years, little published data is available regarding possible applications of high pressure homogenisation for dairy products. The objective of this work was to compare the effects of conventional (18 MPa, two-stage) and single or two-stage high pressure homogenisation (HPH) at 50–200 MPa on some properties of raw whole bovine milk (∼4% fat). Fat globule size decreased as HPH pressure increased and, under certain conditions of temperature and pressure, HPH yielded significantly smaller fat globules than conventional homogenisation. Fat globule size was also affected by milk inlet temperature. The pH of all homogenised milk samples decreased during 24 h refrigerated storage. Total bacterial counts of milk were decreased significantly (P<0·05) for milk samples HPH-treated at 150 or 200 MPa. Whiteness and rennet coagulation properties of milk were unaffected or enhanced, respectively, as homogenisation pressure was increased. Average casein micelle size decreased slightly when skim milk was homogenised at 200 MPa. Thus, HPH treatment has several, potentially significant, effects on milk properties.
pH-Sensing 96-well microtitre plates for the characterization of acid production by dairy starter cultures
Authors: John Gernot T , Goelling Detlef , Klimant Ingo , Schneider Holger , Heinzle Elmar
Published: August 2003

A new method for characterization of acid production by dairy starter cultures is presented. Microplates with integrated optical pH sensors are developed. Two fluorophores, a pH-sensitive and a pH-insensitive one are immobilised at the bottom of a polystyrene 96-well microtitre plate. The pH-insensitive fluorophore serves as an internal reference and makes calibration unnecessary. The sensor measures pH accurately in optically well-defined media. Particles and fluorophores contained in the bulk medium disturbed the measurements. Despite these disturbances it was possible to clearly sense differences in inoculum type and in inoculum sizes of cultures of Lactococcus lactis and of Streptococcus thermophilus at 30 and 37°C. Besides a pH-related signal there is information about other changes during milk fermentation. The cultivation results were compared with those from the established CINAC-method. From this comparison it can be concluded that the new method can be used reliably to characterize particularly a large number of strains for screening purposes but also for quality control.
Modelling casein aggregation and curd firming in goats' milk from backscatter of infrared light
Authors: Castillo Manuel Z , Payne Fred A , Hicks Clair L , Laencina José S , López María-Belén M
Published: August 2003

A kinetic model was proposed for describing the curd assembly of skimmed goats' milk during enzymic coagulation. The enzymic coagulation of milk was monitored using an optical sensor that measured diffuse reflectance (light backscatter) at 880 nm. The appearance of a shoulder, at low temperatures and protein concentrations, in the diffuse reflectance ratio profile after the inflection point of the curve (Tmax) appeared to separate the aggregation and curd firming steps. The diffuse reflectance ratio profile after Tmax was attributed to the overlapping of casein micelles aggregation and curd firming reactions. The developed kinetic model combined a second order reaction model to describe aggregation reactions and a first order reaction model to describe firming processes reactions. A completely randomised block design with three replications was used to determine the effect of protein concentration and temperature on kinetic constants. Milk was adjusted to three levels of protein (30, 50 and 70 g/kg), and coagulated at five temperatures (20, 25, 30, 35 and 40°C) to test a wide range of processing conditions. Data points from each profile after Tmax were fitted to the proposed model using non-linear regression. The average R2 and standard error of prediction (SEP) for 45 tests conducted were in the range of 0·9975±0·0027 and 0·0081±0·0037, respectively. A significant increase in characteristic times for aggregation (τ2) and curd firming processes (τ1) were found when temperature decreased or protein increased. Theoretical asymptotic value of reflectance ratio, R∞, increased with increasing level of protein and temperature (P<0·05). The parameter β1, which represented the fraction of diffuse reflectance ratio attributed to aggregation, decreased with increasing temperature and decreasing protein.
Synthetic peptides as substrate for assaying the proteolytic activity of Lactobacillus helveticus
Authors: Caira Simonetta , Ferranti Pasquale , Gatti Monica , Fornasari Maria Emanuela , Barone Francesca , Lilla Sergio , Mucchetti Germano , Picariello Gianluca , Chianese Lina , Neviani Erasmo , Addeo Francesco
Published: August 2003

Four Lactobacillus helveticus strains were studied for proteolytic capacity and general aminopeptidase (AP) and X-Pro dipeptidyl aminopeptidase (DAP) activity. The rate of hydrolysis and the activity against synthetic substrates with N-terminal residues of Arg, Lys, Leu, Glu or Pro, varied markedly among the strains. The X-Pro DAP activity was consistently high. The crude cell-wall and cytoplasm extracts from strain Lb. helveticus ISLC59 were analysed thoroughly for their proteolysis ability by using four synthetic peptide substrates, including αs1-CN(f1-23). Peptides formed during in vitro hydrolysis of the synthetic substrates by cell wall and cytoplasm preparations were identified by LC-ESI/MS. In doing so, it was possible to infer a prevalent endopeptidase activity splitting Lys7-His8 and Gln13-Glu14 bonds in the cytoplasm, and to deduce a secondary activity, which hydrolysed Glu14-Val15, Leu16-Asn17, Glu18-Asn19 and Lys3-His4 bonds lacking in the cell-wall. The presence of exopeptidases, as mainly AP, DAP, and carboxypeptidase (CPase) was deduced from the formation of several N- and C-terminally truncated peptides sets. The AP activity was higher in the cell-wall layer, where CPase activity was absent. The in vitro assays with cell extracts of the Lb. helveticus ISLC59 strain revealed extensive exopeptidase and endopeptidase activities. In several cases, the hydrolytic system of Lb. helveticus that splits in vitro αs1-CN(f1-23) peptide bonds was similar to that of Lactococcus lactis. The effects were also compared with those occurring in vivo in hard cheese such as Grana Padano.
The Christianisation of Rural Palestine during Late Antiquity
Authors: BAR DORON
Published: August 2003

Focusing on the rural zones of Palestine and exploiting extensive archaeological research permits a re-examination of the traditional view that much of Palestine had been Christianised by the late fourth century. This article suggests that the process of adopting Christianity in the countryside was far more gradual than previously believed. While the map of holy sites in Palestine had largely taken shape by the end of the fourth century, the conversion of the population only achieved real momentum during the fifth and sixth centuries. Research on the community churches of Palestine, in particular on their location in the villages, reveals that Christian penetration into the countryside stemmed from internal social developments and was not institutional in inspiration.
Baroclinic characteristics of frictionally destabilized abyssal overflows
Authors: SWATERS GORDON E.
Published: August 2003

Observations show that the near-sill dynamics of dense abyssal overflows is variable and is governed, to a significant extent, by a balance between rotation, bottom friction and downslope acceleration due to gravity. Numerical simulations indicate that the near-sill downslope velocities are comparable to the phase/group velocities of long internal gravity waves. This suggests the possibility that overflows can become supercritical and destabilized by bottom friction. A theory is presented for the frictional destabilization of rotating abyssal overflows and the accompanying baroclinic coupling with the overlying ocean. This mode of transition allows for the formation of downslope and alongslope propagating periodic bores or pulses in the overflow and the generation of amplifying long internal gravity waves in the overlying ocean, and may help to explain aspects of the observed variability which seem unrelated to purely inertial baroclinic instability.
Particle clouds in homogeneous and stratified environments
Authors: BUSH JOHN W. M. , THURBER B. A. , BLANCHETTE F.
Published: August 2003

We examine the settling of monodisperse heavy particles released into a fluid when the resulting motion is sufficiently vigorous that the particle cloud initially assumes the form of a turbulent thermal. A laboratory study is complemented by numerical simulations of particle cloud dynamics in both homogeneous and stratified ambients. In the homogeneous ambient, the cloud generated by a total buoyancy excess $Q= g'N_pV_p$, where $g'$ is the reduced gravity of the $N_p$ spherical particles of volume $V_p\,{=}\,{4\upi a^3}/3$, evolves in a manner consistent with a classical fluid thermal. The cloud grows through turbulent entrainment and decelerates until its speed is exceeded by that of the individual particles $w_s$, at which point the particles rain out as individuals. For particle Reynolds numbers $\hbox{\it Re}_p\,{=}\,w_s a/\nu$ in the range of 0.1–300, the fallout height $Z_f$ is found to be $Z_f/a\,{=}\,(11 \pm 2) (Q^{1/2}/(w_sa))^{0.83}$. For high $\hbox{\it Re}_p$ particles, the fallout height assumes the simple form: $Z_f/a\,{=}\,(9 \pm 2) N_p^{1/2}$. Following fallout, the particles sink at their individual settling speeds in the form of a bowl-shaped swarm. In a stratified environment characterized by a constant Brunt–Väisälä frequency $N$, the mode of fallout depends explicitly on the stratified cloud number, $N_s\,{=}\,w_s Q^{-1/4} N^{-1/2}$. For $N_s\,{<}\,1$, the cloud overshoots, rebounds past, then intrudes at the neutral height, $Z_N$, of the equivalent fluid thermal. The particles fall out between the depth of maximum penetration and the spreading neutral cloud, and may be distributed over a relatively broad area. For $N_s\,{>}\,1$, the particles fall out in the form of a bowl-shaped swarm at a height $Z_f\,{<}\,Z_N$, thus giving rise to a relatively localized deposit. For $N_s\,{>}\,4$, the fallout height is largely uninfluenced by the stratification and is adequately described by the homogeneous result. Regardless of $N_s$, following particle fallout in a stratified ambient, the fluid entrained by the thermal ascends and intrudes at a rebound height given to leading order by ${3} Z_f/4$. Criteria for three distinct modes of particle deposition in a stratified ambient are developed.
Collisional transport of electrons in disturbed magnetic field
Authors: KANNO RYUTARO
Published: August 2003

A path integral method is applied to a statistical analysis of electron transport described as a Langevin equation in a disturbed magnetic field line structure; in particular, the transition probability of electrons strongly tied to field lines is considered. When the effect of the Coulomb collisions is interpreted as the Gaussian white noise in configuration space, the radial transport of electrons in the chaotic field line structure is different from Brownian diffusion with the diffusion coefficient of field lines, even if a sufficiently small diffusion coefficient of the collisions is considered.
Nonlinear stability of axisymmetric ideal magnetohydrodynamic flows
Authors: KHATER A. H. , CALLEBAUT D. K. , MOAWAD S. M.
Published: August 2003

In this paper the general theory developed by Vladimirov et al. is extended to nonlinear (Lyapunov) stability for axisymmetric (invariant under rotations around a fixed axis) solutions of the ideal incompressible magnetohydrodynamic flows for a particular situation, namely arbitrary field and poloidal flow. The appropriate norm is a sum of magnetic and kinetic energies and the mean square vector potential of the magnetic field.
Modular event-based systems
Authors: FIEGE LUDGER , MÜHL GERO , GÄRTNER FELIX C.
Published: August 2003

Event-based systems are developed and used to integrate components in loosely coupled systems. Research and product development have focused so far on efficiency issues but neglected methodological support to build such systems. In this article, the modular design and implementation of an event system is presented which supports scopes and event mappings, two new and powerful structuring methods that facilitate engineering and coordination of components in event-based systems. We give a formal specification of scopes and event mappings within a trace-based formalism adapted from temporal logic. This is complemented by a comprehensive introduction to the event-based style, its benefits and requirements.
Scholars in Households: Refiguring the Learned Habitus, 1480–1550
Authors: Algazi Gadi
Published: August 2003

Argument

Until the fifteenth century, celibacy was the rule among Christian scholars of northwestern Europe. Celibacy was a major element of the codified cultural representation of the scholar and his specific way of life, sustained by peculiar institutional arrangements and daily routines. Founding family households implied therefore a major reorganization of the scholar’s way of life. Broadly speaking, this involved refashioning the scholarly habitus (understood as a system of durable and transposable social dispositions), redefining social relations, and developing the necessary material infrastructure. The paper focuses on three aspects of this process during a period characterized by uncertainty and experimentation. It discusses the structure of scholars’ families, arguing that at least until the middle of the sixteenth century, received models still persisted, while new viable models for articulating family reproduction with the transmission of scholarly dispositions had not yet crystallized. It then turns to the reorganization of domestic space, focusing on the different uses of the study to manage social distance and regulate domestic relations. Finally, among the different manifestations of the scholarly habitus, it argues that the emotional detachment of learned men was itself a learned habit. The well-documented discussion of competing options for organizing scholars’ family households and cultivating an acquired nature in academic settings provides an exceptional occasion to examine the way a group habitus is reshaped and, explore the cultural work involved in this process.
On the Professorial Voice
Authors: Clark William
Published: August 2003

Argument

Much recent research has established the importance of visualization in modern science. This essay treats, instead, of the continued importance of the aural and oral: the professorial voice. The professor remains important for science since so many scientists still instantiate this persona and, as is here argued, a “voice” constitutes an essential feature of it. The form of the essay reflects its contents. From the Middle Ages until well into the modern era, the archetypal professorial genre was the disputation, an oral event recast in written form. Apropos of the traditional disputation, this essay begins with a disquisition more or less to the point. It concerns Nietzsche’s first major publication, which violated norms for the proper professorial voice, thus accelerated the destruction of his academic career. The essay then presents six theses on the professorial voice. The theses treat relevant aspects of the professorial voice from the Sophists onward. It is argued, in Weberian terms, that the professorial voice or persona embodies elements of charismatic and traditional authority which coexist with and condition the rational authority or “objectivity” of science.
Experimentalists in the Republic of Letters
Authors: Otto Sibum H.
Published: August 2003

Argument

Within the Republic of Letters the art of experiment led to immense reorientation and an extensive redrawing of the enlightened map of natural knowledge. This paper will investigate the formative period of the exact sciences from the late eighteenth to the nineteenth century when the persona of the experimentalist as a scientific expert was shaped. The paper focuses on Moritz Hermann Jacobi’s experimental knowledge derived from his modeling of an electro-magnetic self-acting machine and the social and epistemological problems of its integration into traditional academic life. His struggle to achieve academic recognition and credibility for his experimental work reflects not just his individual quandary, but important structural problems of the historical development of experimental knowledge traditions and science in what has been called the “second scientific revolution.”
“Be what you would seem to be”: Samuel Smiles, Thomas Edward, and the Making of a Working-Class Scientific Hero
Authors: Secord Anne
Published: August 2003

Argument

This paper examines the effort that was involved in sustaining the nineteenth-century middle-class ideological fabrication of the image of the working-class scientific autodidact. The construction and reception of Samuel Smiles’ biography of the Scottish cobbler and naturalist Thomas Edward provides a way to investigate this process in detail and to show how Smiles’ conception of the scientific persona related to the “politics of character” in mid-Victorian Britain. Edward’s own response to the biography offers an unusual opportunity to analyze the making of a Victorian scientific hero, who, in the process of being fitted to Smiles’ notion of a scientific persona, came to feel that he had been robbed of his life.
Survey of meshless and generalized finite element methods: A unified approach
Authors: Babuška Ivo , Banerjee Uday , Osborn John E.
Published: August 2003

In the past few years meshless methods for numerically solving partial differential equations have come into the focus of interest, especially in the engineering community. This class of methods was essentially stimulated by difficulties related to mesh generation. Mesh generation is delicate in many situations, for instance, when the domain has complicated geometry; when the mesh changes with time, as in crack propagation, and remeshing is required at each time step; when a Lagrangian formulation is employed, especially with nonlinear PDEs. In addition, the need for flexibility in the selection of approximating functions (e.g., the flexibility to use non-polynomial approximating functions), has played a significant role in the development of meshless methods. There are many recent papers, and two books, on meshless methods; most of them are of an engineering character, without any mathematical analysis.

In this paper we address meshless methods and the closely related generalized finite element methods for solving linear elliptic equations, using variational principles. We give a unified mathematical theory with proofs, briefly address implementational aspects, present illustrative numerical examples, and provide a list of references to the current literature.

The aim of the paper is to provide a survey of a part of this new field, with emphasis on mathematics. We present proofs of essential theorems because we feel these proofs are essential for the understanding of the mathematical aspects of meshless methods, which has approximation theory as a major ingredient. As always, any new field is stimulated by and related to older ideas. This will be visible in our paper.
Continuous dependence and error estimation for viscosity methods
Authors: Cockburn Bernardo
Published: August 2003

In this paper, we review some ideas on continuous dependence results for the entropy solution of hyperbolic scalar conservation laws. They lead to a complete L^\infty(L^1)-approximation theory with which error estimates for numerical methods for this type of equation can be obtained. The approach we consider consists in obtaining continuous dependence results for the solutions of parabolic conservation laws and deducing from them the corresponding results for the entropy solution. This is a natural approach, as the entropy solution is nothing but the limit of solutions of parabolic scalar conservation laws as the viscosity coefficient goes to zero.
A mathematical view of automatic differentiation
Authors: Griewank Andreas
Published: August 2003

Automatic, or algorithmic, differentiation addresses the need for the accurate and efficient calculation of derivative values in scientific computing. To this end procedural programs for the evaluation of problem-specific functions are transformed into programs that also compute the required derivative values at the same numerical arguments in floating point arithmetic. Disregarding many important implementation issues, we examine in this article complexity bounds and other more mathematical aspects of the program transformation task sketched above.
Entropy stability theory for difference approximations of nonlinear conservation laws and related time-dependent problems
Authors: Tadmor Eitan
Published: August 2003

We study the entropy stability of difference approximations to nonlinear hyperbolic conservation laws, and related time-dependent problems governed by additional dissipative and dispersive forcing terms. We employ a comparison principle as the main tool for entropy stability analysis, comparing the entropy production of a given scheme against properly chosen entropy-conservative schemes.

To this end, we introduce general families of entropy-conservative schemes, interesting in their own right. The present treatment of such schemes extends our earlier recipe for construction of entropy-conservative schemes, introduced in Tadmor (1987b). The new families of entropy-conservative schemes offer two main advantages, namely, (i) their numerical fluxes admit an explicit, closed-form expression, and (ii) by a proper choice of their path of integration in phase space, we can distinguish between different families of waves within the same computational cell; in particular, entropy stability can be enforced on rarefactions while keeping the sharp resolution of shock discontinuities.

A comparison with the numerical viscosities associated with entropy-conservative schemes provides a useful framework for the construction and analysis of entropy-stable schemes. We employ this framework for a detailed study of entropy stability for a host of first- and second-order accurate schemes. The comparison approach yields a precise characterization of the entropy stability of semi-discrete schemes for both scalar problems and systems of equations.

We extend these results to fully discrete schemes. Here, spatial entropy dissipation is balanced by the entropy production due to time discretization with a suffciently small time-step, satisfying a suitable CFL condition. Finally, we revisit the question of entropy stability for fully discrete schemes using a different approach based on homotopy arguments. We prove entropy stability under optimal CFL conditions.
Geological record of an acidic environment driven by iron hydrochemistry: The Tinto River system
Authors: Fernández‐Remolar David C. , Rodriguez Nuria , Gómez Felipe , Amils Ricardo
Published: August 2003

The existence of possible hematitic strata on the surface of Mars demands a search for terrestrial analogues formed in unusual environments. This will help us to recognize and interpret environmental and, perhaps, biological signatures preserved in Mars' hematites. Such an analogue would allow us to establish valid reference systems based on geomicrobial and biogeochemical signatures. Two different aspects place the Tinto River inside the boundaries of a natural extreme system: its high level of biological diversity and the presence of fluvial rocks formed in the same acidic conditions as in the modern system, which could predate the Tertiary. Study of both the modern system and the ancient system is necessary to understand the formation of biosignatures. A chemolithotrophic community that biooxidizes the Iberian Pyritic Belt, acidifying water (pH between 0.9 and 3.0) and favoring high concentrations of ferric iron in solution (up to 20 g·L−1), maintains this iron‐driven system. In spite of these extreme conditions, high microbial diversity was found. Its acidic bacteria, archaea, and eukarya constitute a complex community supported by algal biomass in highly stable hydrochemical conditions, which are achieved through iron buffering. The pH is maintained at constant low levels even at very high water dilution. In these conditions, iron minerals as oxyhydroxides, hydroxides, and sulfates are formed. The modern and recent parageneses contrast with the ancient Tinto River terrace mineral associations, which show dehydrated and desulfated iron oxides. If this dehydration process is considered, these Tinto River ironstones may be a key for knowing some aquatic habitats, which may have hosted a part of the early Mars biosphere.
Simplifying multiobjective optimization: An automated design methodology for the nondominated sorted genetic algorithm‐II
Authors: Reed Patrick , Minsker Barbara S. , Goldberg David E.
Published: August 2003

Many water resources problems require careful balancing of fiscal, technical, and social objectives. Informed negotiation and balancing of objectives can be greatly aided through the use of evolutionary multiobjective optimization (EMO) algorithms, which can evolve entire tradeoff (or Pareto) surfaces within a single run. The primary difficulty in using these methods lies in the large number of parameters that must be specified to ensure that these algorithms effectively quantify design tradeoffs. This technical note addresses this difficulty by introducing a multipopulation design methodology that automates parameter specification for the nondominated sorted genetic algorithm‐II (NSGA‐II). The NSGA‐II design methodology is successfully demonstrated on a multiobjective long‐term groundwater monitoring application. Using this methodology, multiobjective optimization problems can now be solved automatically with only a few simple user inputs.