bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality of service for satellite IP networks: a survey
Authors: Kota Sastri , Marchese Mario
Published: July 2003

The future media rich applications such as media streaming, content delivery distribution and broadband access require a network infrastructure that offers greater bandwidth and service level guarantees. As the demand for new applications increases, ‘best effort’ service is inadequate and results in lack of user satisfaction. End‐to‐end quality of service (QoS) requires the functional co‐operation of all network layers. To meet future application requirements, satellite is an excellent candidate due to features such as global coverage, bandwidth flexibility, broadcast, multicast and reliability. At each layer, the user performance requirements should be achieved by implementation of efficient bandwidth allocation algorithms and satellite link impairment mitigation techniques.

In this paper, a QoS framework for satellite IP networks including requirements, objectives and mechanisms are described. To fully understand end‐to‐end QoS at each layer, QoS parameters and the current research are surveyed. For example at physical layer (modulation, adaptive coding), link layer (bandwidth allocation), network layer (IntServ/DiffServ, MPLS traffic engineering), transport layer (TCP enhancements, and alternative transport protocols) and security issues are discussed. Some planned system examples, QoS simulations and experimental results are provided. The paper also includes the current status of the standardization of satellite IP by ETSI, ITU and IETF organizations. Copyright © 2003 John Wiley & Sons, Ltd.
Present possibilities of thin‐layer analysis by GDOES
Authors: Hoffmann Volker , Dorka Roland , Wilken Ludger , Hodoroaba Vasile‐Dan , Wetzig Klaus
Published: August 2003

The analysis of thin layers of thickness ∼100 nm has become a new field of application for glow discharge optical emission spectroscopy (GDOES). In this paper an overview is given of the experiences and possibilities gained by the authors in later years at their research, development and application of GDOES.

During GDOES analysis of a multilayer system the depth resolution was determined using the inverse maximal slope method. Under optimized discharge conditions a depth resolution of ∼25 nm at 100 nm depth was achieved. The gas flow in a Grimm‐type source for glow discharge mass spectrometry (GDMS) was simulated and a correlation between calculated pressure and crater shape was found. Cleanness of the sample and source turned out to be essential for a fast stabilization time and reduction of the influence of light elements and molecules. Thereby, a 10 nm layer at the top surface of a sample could be quantified. Apart from the influence of density, the reflectivity of the sample surface is discussed. It is shown that a high sample reflectivity can cause up to 100% more light to be measured by the spectrometer. Copyright © 2003 John Wiley & Sons, Ltd.
Secondary electron emission coefficients of standard samples for GDOES
Authors: Guillot Ph. , Belenguer Ph. , Therese L. , Lavoine V. , Chollet H.
Published: August 2003

The purpose of this work is to determine Paschen curves for standard samples used for calibration in glow discharge optical emission spectroscopy. The experimental set‐up is described for measuring the breakdown voltage of a material–gas couple. This voltage corresponds to the Townsend regime of the discharge. Several materials (copper, nickel, iron and titanium) have been studied in the presence of argon and the results are presented here. From this preliminary work, effective secondary emission coefficients have been calculated versus the reduced electric field for each standard sample. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of anodic films on Nb and NbNx by glow discharge optical emission spectroscopy
Authors: Habazaki H. , Matsuo T. , Konno H. , Shimizu K. , Matsumoto K. , Takayama K. , Oda Y. , Skeldon P. , Thompson G. E.
Published: August 2003

Sputter‐deposited niobium layers containing nitrogen form anodic films with resultant capacitance and leakage current density little influenced by annealing up to 523 K. The nitrogen species incorporated into the anodic oxide films at the alloy/film interface are distributed in the inner 70–75% of the film thickness, with fine bubbles containing high‐pressure N2O gas being evident. Glow discharge optical emission spectroscopy (GDOES) analysis reveals their continued presence after annealing at 523 K. The insignificant changes in GDOES depth profiles also suggest that the formation of low‐valent oxide at the metal/film interface as a result of annealing is not responsible for the behaviour. For thermal treatments above 400 K, capacitances and leakage currents increase significantly for niobium, with nitrogen additions diminishing the effects. Such behaviour is suggested to arise from suppression of mechanical damage to films through the presence of highly pressurized gas in the inner part of the films. Copyright © 2003 John Wiley & Sons, Ltd.
Adjusting power for a baseline covariate in linear models
Authors: Glueck Deborah H. , Muller Keith E.
Published: July 2003

The analysis of covariance provides a common approach to adjusting for a baseline covariate in medical research. With Gaussian errors, adding random covariates does not change either the theory or the computations of general linear model data analysis. However, adding random covariates does change the theory and computation of power analysis. Many data analysts fail to fully account for this complication in planning a study. We present our results in five parts. (i) A review of published results helps document the importance of the problem and the limitations of available methods. (ii) A taxonomy for general linear multivariate models and hypotheses allows identifying a particular problem. (iii) We describe how random covariates introduce the need to consider quantiles and conditional values of power. (iv) We provide new exact and approximate methods for power analysis of a range of multivariate models with a Gaussian baseline covariate, for both small and large samples. The new results apply to the Hotelling–Lawley test and the four tests in the “univariate” approach to repeated measures (unadjusted, Huynh‐Feldt, Geisser‐Greenhouse, Box). The techniques allow rapid calculation and an interactive, graphical approach to sample size choice. (v) Calculating power for a clinical trial of a treatment for increasing bone density illustrates the new methods. We particularly recommend using quantile power with a new Satterthwaite‐style approximation. Copyright © 2003 John Wiley & Sons, Ltd.
Error in timing in regression with observed longitudinal measurements
Authors: Wang C. Y. , Huang Yijian
Published: July 2003

We consider regression analysis of a disease outcome in relation to longitudinal data which are observations from a random effects model. The covariate variables of interest are the values of the underlying trajectory at some time points, which may be fixed or subject‐specific. Because the underlying random coefficients are unknown, the covariates to the primary model are generally unobserved. In addition, measurements are often not observed at the time points of interest. A motivating example to our model is the effects of age at adiposity rebound and the associated body mass index on the risk of adult obesity. The adiposity rebound is a time point at which the trajectory of a child's body fatness declines to a minimum. This general error in timing problem may be applied to an analysis when time‐dependent marker variables follow a polynomial model in which the effect of a local maximum or minimum point may be of interest. It can be seen that directly applying estimated covariates, possibly obtained from estimated time points, may lead to bias. Estimation procedures based on expected estimating equations, regression calibration and simulation extrapolation are applied to this problem. Copyright © 2003 John Wiley & Sons, Ltd.
Estimation of k for the poly‐k test with application to animal carcinogenicity studies
Authors: Moon Hojin , Ahn Hongshik , Kodell Ralph L. , Lee J. Jack
Published: July 2003

This paper extends the survival‐adjusted Cochran–Armitage test in order to achieve improved robustness to a variety of tumour onset distributions. The Cochran–Armitage test is routinely applied for detecting a linear trend in the incidence of a tumour of interest across dose groups. To improve the robustness to the effects of differential mortality across groups, Bailer and Portier introduced the poly‐3 test by a survival adjustment using a fractional weighting scheme for subjects not at full risk of tumour development. The performance of the poly‐3 test depends on how closely it represents the correct specification of the time‐at‐risk weight in the data. Bailer and Portier further suggested that this test can be improved by using a general k reflecting the shape of the tumour onset distribution. In this paper, we propose a method to estimate k by equating the empirical lifetime tumour incidence rate obtained from the data based on the fractional weighting scheme to a separately estimated cumulative lifetime tumour incidence rate. This poly‐k test with the statistically estimated k appears to perform better than the poly‐3 test which is conducted without prior knowledge of the tumour onset distribution. Our simulation shows that the proposed method improves the robustness to various tumour onset distributions in addition to the robustness to the effects of mortality achieved by the poly‐3 test. Large sample properties are shown via simulations to illustrate the consistency of the proposed method. The proposed methods are applied to analyse two real data sets. One is to find a dose‐related linear trend on animal carcinogenicity, and the other is to test an effect of calorie restriction on experimental animals. Copyright © 2003 John Wiley & Sons, Ltd.
Characterizing classes of antiretroviral drugs by genotype
Authors: Foulkes A. S. , DeGruttola V.
Published: July 2003

This paper develops methods for using HIV‐1 genotypic information to group patients who are expected to have similar patterns of sensitivity or resistance to two or more drugs. The methods presented are an extension of prediction based classification to handle multiple drug responses. Here, the goal is to determine the probability that one antiretroviral therapy will be more favourable than another for an individual given the specific genotypic or other characteristics of the infecting viral population. This approach requires a model relating genotype to a vector of drug specific phenotypic responses. A comparison of Nelfinavir and Indinavir is provided using 2746 protease sequences and corresponding in vitro sensitivity assays provided to us by the Virco Group. Copyright © 2003 John Wiley & Sons, Ltd.
Use of max and min scores for trend tests for association when the genetic model is unknown
Authors: Zheng Gang
Published: July 2003

In case‐control studies, the Cochran–Armitage (CA) trend test is powerful for detection of an association between a risk allele and a marker. To apply this test, a score should be assigned to the genotypes based on the genetic model. When the underlying genetic model is unknown, the trend test statistic is a function of the score. In this paper, simple procedures are given to obtain two scores (max and min), which respectively maximize and minimize the CA trend test statistics for genetic associations. These two scores can be used to examine the effect of the choice of scores on the test of no association. When the CA trend test statistic with the max (or min) score is less (or greater) than a prespecified value, the conclusion is clear: we will accept (or reject) the null hypothesis of no association for any scores used. When this value is less than the CA trend test statistic with the max score but greater than the one with the min score, the decision of whether or not to reject the null hypothesis depends on the choice of scores. In this situation, the CA trend test with a prespecified score cannot be used without careful scientific justification of the choice of scores. The use of max and min scoring schemes is applied to a real data set. Published in 2003 by John Wiley & Sons, Ltd.
On the performance of random‐coefficient pattern‐mixture models for non‐ignorable drop‐out
Authors: Demirtas Hakan , Schafer Joseph L.
Published: July 2003

Random‐coefficient pattern‐mixture models (RCPMMs) have been proposed for longitudinal data when drop‐out is thought to be non‐ignorable. An RCPMM is a random‐effects model with summaries of drop‐out time included among the regressors. The basis of every RCPMM is extrapolation. We review RCPMMs, describe various extrapolation strategies, and show how analyses may be simplified through multiple imputation. Using simulated and real data, we show that alternative RCPMMs that fit equally well may lead to very different estimates for parameters of interest. We also show that minor model misspecification can introduce biases that are quite large relative to standard errors, even in fairly small samples. For many scientific applications, where the form of the population model and nature of the drop‐out are unknown, interval estimates from any single RCPMM may suffer from undercoverage because uncertainty about model specification is not taken into account. Copyright © 2003 John Wiley & Sons, Ltd.
Two bivariate geometrically defined reference regions with applications to male reproductive hormones and human growth
Authors: Petersen Jørgen Holm
Published: July 2003

Two conceptually simple two‐dimensional reference charts are described. The charts are characterized analytically, but also by geometric properties that are easily communicated to subject‐matter researchers – the users of such charts. For both charts, the proposed estimators are non‐parametric, so no distributional assumptions are needed about the two‐dimensional response. An important example that will serve to motivate and illustrate one of the charts is the study of the human reproductive hormones Inhibin B and FSH. A low Inhibin B concentration combined with a high FSH concentration is an indication that something may be wrong in the seminal cells which produce semen, and such measurements help in the process of distinguishing between different reasons for infertility. The aim in the study of the human reproductive hormones was to give a two‐dimensional reference curve for the non‐normally distributed hormone measurements while taking into account that some measurements were left‐censored because of a detection limit in the assay used to measure the concentrations. Copyright © 2003 John Wiley & Sons, Ltd.
Separation of individual‐level and cluster‐level covariate effects in regression analysis of correlated data
Authors: Begg Melissa D. , Parides Michael K.
Published: July 2003

The focus of this paper is regression analysis of clustered data. Although the presence of intracluster correlation (the tendency for items within a cluster to respond alike) is typically viewed as an obstacle to good inference, the complex structure of clustered data offers significant analytic advantages over independent data. One key advantage is the ability to separate effects at the individual (or item‐specific) level and the group (or cluster‐specific) level. We review different approaches for the separation of individual‐level and cluster‐level effects on response, their appropriate interpretation and give recommendations for model fitting based on the intent of the data analyst. Unlike many earlier papers on this topic, we place particular emphasis on the interpretation of the cluster‐level covariate effect. The main ideas of the paper are highlighted in an analysis of the relationship between birth weight and IQ using sibling data from a large birth cohort study. Copyright © 2003 John Wiley & Sons, Ltd.
Architecting and implementing distributed Web applications using the graph‐oriented approach
Authors: Cao Jiannong , Ma Xiaoxing , Chan Alvin T. S. , Lu Jian
Published: July 2003

This paper presents a graph‐oriented framework, called WebGOP, for architecture modeling and programming of Web‐based distributed applications. WebGOP is based on the graph‐oriented programming (GOP) model, under which the components of a distributed program are configured as a logical graph and implemented using a set of operations defined over the graph. WebGOP reshapes GOP with a reflective object‐oriented design, which provides powerful architectural support in the World Wide Web environment. In WebGOP, the architecture graph is reified as an explicit object which itself is distributed over the network, providing a graph‐oriented context for the execution of distributed applications. The programmer can specialize the type of graph to represent a particular architecture style tailored for an application. WebGOP also has built‐in support for flexible and dynamic architectures, including both planned and unplanned dynamic reconfiguration of distributed applications. We describe the WebGOP framework, a prototypical implementation of the framework on top of SOAP, and a performance evaluation of the prototype. The prototype demonstrated the feasibility of our approach. Results of the performance evaluation showed that the overhead introduced by WebGOP over SOAP is reasonable and acceptable. Copyright © 2003 John Wiley & Sons, Ltd.
A security framework for reflective Java applications
Authors: Caromel Denis , Vayssière Julien
Published: July 2003

The advent of component‐based reflective applications raises the issue of protecting baselevel components from the actions performed by metalevel components. However, by their very nature, reflective applications are far more difficult to secure than non‐reflective applications, which certainly explains why the problem has received very little attention so far. In this paper we present a security framework for enforcing access control between metalevel components and the baselevel components they reflect on. Rather than designing a new security architecture from scratch, we extend the standard security architecture of Java to provide security for a fully‐functional proxy‐based MOP for Java. We implement a number of well‐known meta‐level behaviors and study their security requirements, the results of which support our design choices. Copyright © 2003 John Wiley & Sons, Ltd.
DIKE: a system supporting the semi‐automatic construction of cooperative information systems from heterogeneous databases
Authors: Palopoli Luigi , Terracina Giorgio , Ursino Domenico
Published: July 2003

In this paper we present DIKE, a system supporting the semi‐automatic construction of cooperative information systems from heterogeneous databases. The input of DIKE consists of the set of databases to belong to the cooperative system. First, DIKE constructs a data repository representing a structured, integrated and consistent description of the information stored in the input databases. The data repository thus constructed is then used as the core structure of a mediator‐like module supporting the user‐friendly integrated access to available data resources. The core of DIKE is the extraction and exploitation of the inter‐schema knowledge (in the form of inter‐schema properties) relative to the involved database schemas. Copyright © 2003 John Wiley & Sons, Ltd.
Substituting outline fonts for bitmap fonts in archived PDF files
Authors: Probets S. G. , Brailsford D. F.
Published: July 2003

As collections of archived digital documents continue to grow the maintenance of an archive, and the quality of reproduction from the archived format, become important long‐term considerations. In particular, Adobe's portable document format (PDF) is now an important ‘final form’ standard for archiving and distributing electronic versions of technical documents. It is important that all embedded images in the PDF, and any fonts used for text rendering, should at the very minimum be easily readable on screen. Unfortunately, because PDF is based on PostScript technology, it allows the embedding of bitmap fonts in Adobe Type 3 format as well as higher‐quality outline fonts in TrueType or Adobe Type 1 formats. Bitmap fonts do not generally perform well when they are scaled and rendered on low‐resolution devices such as workstation screens.

The work described here investigates how a plug‐in to Adobe Acrobat enables bitmap fonts to be substituted by corresponding outline fonts using a checksum matching technique against a canonical set of bitmap fonts, as originally distributed. The target documents for our initial investigations are those PDF files produced by LATEX systems when set up in a default (bitmap font) configuration. For all bitmap fonts where recognition exceeds a certain confidence threshold replacement fonts in Adobe Type 1 (outline) format can be substituted with consequent improvements in file size, screen display quality and rendering speed. The accuracy of font recognition is discussed together with the prospects of extending these methods to bitmap‐font PDF files from sources other than LATEX. Copyright © 2003 John Wiley & Sons, Ltd.
Pathology of lumbar nerve root compression Part 1: Intraradicular inflammatory changes induced by mechanical compression
Authors: Kobayashi Shigeru , Yoshizawa Hidezo , Yamada Shuuichi
Published: August 2003

Study design: This study is to investigate the intraradicular inflammation induced by mechanical compression using in vivo model.

Objectives: The relationship between the intraradicular edema and nerve fiber degeneration induced by mechanical compression was determined in the nerve root.

Summary of background data: Recently some studies reported that mechanical compression increased microvascular permeability of the endoneurial capillaries and resulted in an intraradicular inflammation. These changes may be an important factor of the pathogenesis of radiculopathy. However, the natural courses of the intraradicular inflammation after mechanical compression are still poorly understood.

Methods: In dogs, laminectomy was performed at L7 and the seventh nerve root was exposed to compression at 7.5 gram force (gf) clipping power. The animals were evaluated at 1 and 3 weeks after clipping. After the appropriate period of nerve root compression, Evans blue albumin (EBA) was injected intravenously. The nerve root sections were divided into two groups. The sections were used to investigate the status of the blood–nerve barrier function under the fluorescence microscope. The other sections were used for light and transmission electron microscopic study.

Results: After 1 and 3 weeks, intraradicular edema was observed not only at the site of compression but also in the peripheral zone of a compressed anterior root and in the central zone of a compressed posterior root. The evidence of active Wallerian degeneration was also seen in the area of intraradicular edema. In addition, the nerve roots showing Wallerian degeneration were infiltrated by inflammatory cells, such as macrophages and mast cells.

Conclusions: Inflammatory reaction, such as Wallerian degeneration, breakdown of blood–nerve barrier and appearance of macrophage, may be deeply involved in radiculitis arising from mechanical compression, and these factors seem to be important in the manifestation of radiculopathy. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Long stemmed total knee arthroplasty with interlocking screws: A computational bone adaptation study
Authors: Nyman Jeffry S. , Hazelwood Scott J. , Rodrigo Juan J. , Martin R. Bruce , Yeh Oscar C.
Published: August 2003

The ability of an interlocking screw fixation technique to minimize bone loss related to stress shielding in the tibia was investigated and compared to the abilities of cement and press‐fit fixation. Full bony ingrowth has been associated with greater stress shielding than partial ingrowth; therefore, the effect of intimate bonding of the stem to bone on subsequent bone loss was also studied. A damage‐ and disuse‐based remodeling theory was coupled with a two‐dimensional finite element model of the tibia to predict changes in bone remodeling following long stemmed total knee arthroplasty (TKA) for four different fixation techniques (cement, press‐fit, interlock with bony ingrowth, and interlock without bony ingrowth). Remodeling changes commenced with the model state variables—bone area fraction, mechanical stimulus, damage, and remodeling activity—at steady‐state values predicted by the intact tibia simulation. After TKA and irrespective of fixation technique, the model predicted elevated remodeling due to disuse, in which more bone was removed than replenished. In regions below the tibial tray and along the cortices, the interlocking stem with full bony ingrowth and the cemented stem caused the least amount of bone loss. An interlocking stem with a smooth, matted finish did not reduce the bone loss associated with interlocking fixation. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Neuropeptides in anterior pituitary development
Authors: Cimini Vincenzo
Published: July 2003

Recent studies using biotechnological methods have achieved significant advances in our knowledge of molecular mechanisms underlying pituitary gland development and the differentiation of pituitary cytotypes. A large number of neuropeptides have been reported in the adult pituitary gland as well as in the central and peripheral nervous system. The early presence of neuropeptides during pituitary development is reviewed here. Neuromedin U (NmU), galanin and the polypeptide 7B2 have been localised to different endocrine cells of the gland. Their expression seems to be manifold even though it is temporally and spatially regulated. There is now firm immunocytochemical evidence that neuropeptides are present during morphogenesis of the pituitary and can be present simultaneously with all pituitary hormones.
Lead toxicosis in cats—a review
Authors: Knight TE , Kumar MSA
Published: August 2003

Although the incidence of lead toxicosis in small animals continues to decrease, it remains a significant malady. We have reviewed the literature of the past 45 years, which revealed 70 cases involving cats. Sources, signs, diagnosis, pathology and treatment of feline lead toxicosis are reviewed.

In 84% of these cases the source of lead was old paint usually from home renovation. The most common signs in cats are anorexia, vomiting, and seizures. The younger individuals seem more likely to show CNS signs. Since signs are often vague, lead toxicosis may be significantly under diagnosed in cats. The gold standard of diagnostic tests is blood lead concentration, although it does not necessarily correlate with total body burden of lead or with metabolic effects including clinical signs. Diagnostic tests including erythropoietic protoporphyrin (EPP), urine aminolevulinic acid, and others are discussed. Gross findings on necropsy are few and include a yellow-brown discoloration of the liver often with a nutmeg-like appearance. Histological examination may reveal pathognomonic inclusion bodies in liver and renal tissues. Characteristic histological changes in the CNS include neuronal necrosis and demyelination.

Treatment of lead toxicosis in cats, as in any species, involves removing the exposure, decontaminating the individual and the environment, supportive care and chelation therapy. The most recently available chelator is succimer (meso 2,3-dimercaptosuccinic acid). Succimer given orally is well tolerated and has a wide margin of safety.

A high index of suspicion of lead toxicosis is warranted in cats since they often present with vague and non-specific signs. With any consistent history owners need to be asked about home renovation. Early diagnosis and treatment affords a good prognosis.
Clinical use of dexmedetomidine as premedicant in cats undergoing propofol–sevoflurane anaesthesia
Authors: Mendes G.M. , Selmi A.L. , Barbudo-Selmi G.R. , Lins B.T. , Figueiredo J.P.
Published: August 2003

The purpose of this report was to evaluate the cardiorespiratory effects and efficacy of dexmedetomidine as a premedicant agent in cats undergoing ovariohysterectomy anaesthetized with propofol–sevoflurane. Cats were randomly divided into two groups of eight animals each. Dexmedetomidine (0.01 mg/kg) or 0.9% saline was administered intravenously (D and S, respectively). After 5 min, propofol was administered intravenously and anaesthesia was maintained with sevoflurane. Heart and respiratory rates, arterial blood pressure, oxygen saturation, rectal temperature and the amount of propofol needed for induction were measured. Premedication with dexmedetomidine reduced the requirement of propofol (6.7±3.8 mg/kg), but induced bradycardia, compared with the administration of saline (15.1±5.1 mg/kg). Recovery quality was significantly better in D but no significant difference in time to return of swallowing reflex was observed between groups (D=2.5±0.5 min;S=3.2±1.8 min). In conclusion, dexmedetomidine is a safe and effective agent for premedication in cats undergoing propofol–sevoflurane anaesthesia with minimal adverse effects.
Electoral Incentives and Policy Preferences: Mixed Motives Behind Party Defections in Japan
Authors: REED STEVEN R. , SCHEINER ETHAN
Published: August 2003

Examining the 1993 split of the Liberal Democratic Party (LDP) in Japan offers an opportunity to gain greater insight into the impact of the various incentives that influence the behaviour of politicians. Surprisingly, previous analyses of the LDP split have been able to demonstrate only weak evidence of any electoral connection driving politicians' decisions. However, by also examining the role of policy preferences (support for reform) and utilizing interaction terms, our analysis takes into account the fact that politicians at different stages in their careers and facing different sorts of electorates respond to electoral factors in very different ways. Our findings thus confirm the importance of the electoral connection. We are also able to add that a variety of other incentives also shape political behaviour and that politicians do not necessarily all respond to similar stimuli in the same way.
Electoral Institutions, Unemployment and Extreme Right Parties: A Correction
Authors: GOLDER MATT
Published: August 2003

In their 1996 article in this Journal, Robert Jackman and Karin Volpert analyse the systematic conditions that influence the electoral success of extreme right parties in sixteen West European countries from 1970 to 1990. In particular, they focus on the effects of unemployment, electoral thresholds and multi-partism.
Growth kinetics and hydrolytic enzyme production of Pseudomonas spp. isolated from pasteurized milk
Authors: Stevenson R Gregory , Rowe Michael T , Wisdom G Brian , Kilpatrick David
Published: August 2003

Psychrotrophs, particularly Pseudomonas spp. are known to be the main determinants of the shelf-life of pasteurized milk and refrigerated raw milk. It is presumed that they mainly cause spoilage through the elaboration of proteinase and lipase enzymes. At the time of this research, under the relevant European Directive, one of the means of determining the quality of pasteurized milk was the pre-incubated count, which involves incubating the milk sample for 5 d at 6°C followed by a plate count. Examination of numerous pre-incubated counts revealed a bimodal rather than a normal distribution indicating that the types of contaminants in pasteurized milk may be as important as their initial concentration. Pseudomonads that gave particularly high (>5×106 cfu/ml) and low (<103 cfu/ml) pre-incubated counts were isolated (high and low count isolates respectively). After the organisms had been subjected to a cold shock no consistent trend between the groups of isolates was detected with respect to lag phase duration. However, the high count isolates consistently had a faster exponential growth rate. Unexpectedly, with the exception of one isolate, the low count isolates produced detectable proteinase and lipase earlier. In addition, with one exception, maximal proteinase and lipase production was observed with the low count isolates. These findings indicate that there is no causal relationship between selective growth advantage and ability to produce proteinase and lipase. It also indicates that the spoilage of pasteurized milk is a complex phenomenon and is worthy of further research.
Effect of stimulation intensity on oxytocin release before, during and after machine milking
Authors: Weiss Daniel , Dzidic Alen , Bruckmaier Rupert M
Published: August 2003

Release of oxytocin (OT) is essential for milk ejection in dairy cows (Lefcourt & Akers, 1983; Bruckmaier & Blum, 1998). During milk ejection, alveolar milk is shifted into the cistern, which causes an increase of intracisternal pressure (Bruckmaier et al. 1994). To initiate maximum milk ejection at the start of milking, increasing OT concentration beyond a threshold level is sufficient (Schams et al. 1983). Increasing OT concentration beyond this threshold has no additional effect on intracisternal pressure, i.e., milk ejection (Bruckmaier et al. 1994). Stimulatory effects of milking by hand or by machine or by suckling are well documented (Gorewit et al. 1992; Bar-Peled et al. 1995; Tancin et al. 1995; Bruckmaier & Blum, 1996). At the start of milking, stimulatory effects of machine milking without pre-stimulation or with a manual pre-stimulation and subsequent machine milking cause the release of comparable amounts of OT (Gorewit & Gassman, 1985; Mayer et al. 1985; Bruckmaier & Blum, 1996), whereas the timing of the applied pre-stimulation is important for the shape of the milk flow curve. Should the pre-stimulation period be too short, or absent altogether, the start of the main milk flow is delayed resulting in a bimodal milk flow profile (Bruckmaier & Blum, 1996). Furthermore, the stimulation of only one teat causes an OT release similar to that caused by stimulation of all four teats (Bruckmaier et al. 2001). However, milk production is greater for hand milking or suckling than for machine milking, possibly owing to higher OT concentrations (Gorewit et al. 1992; Bar-Peled et al. 1995).
Factors affecting mouthpiece chamber vacuum in machine milking
Authors: Borkhus Marianne , Rønningen Odd
Published: August 2003

The vacuum in the mouthpiece chamber (MPC) was measured in a factorial trial with two liners (DeLaval 964008-01 and DeLaval 999007-03), two pulsator ratios (60 and 70%) and morning and evening milking over eight milkings of ten cows. Teat length and diameter were measured before and after milking, and maximum milk flow rate and depth of penetration of the teat into the teatcup were also recorded. The MPC vacuum at peak flow rate was classified as stable, at various levels, in 79% of the recordings. In the rest of the milkings the vacuum declined gradually, and this decline was associated with gradually deeper penetration of the teat into the teatcup. The DeLaval 964008-01 liner with the narrower bore and larger mouthpiece opening gave lower MPC vacuum at peak flow rate than did the wider bore DeLaval 999007-03 with the smaller mouthpiece opening. Morning milking gave higher MPC vacuum than evening milking. Increased maximum milk flow rate and increased length and diameter of the teat gave decreased MPC vacuum. The teats were longer before milking in the morning than in the evening. However, during peak flow rate, the teats had penetrated deeper into the teatcup in the evening than in the morning. A marked change in MPC vacuum in the transition to the period of flow rate can be used to identify the start of over-milking of an individual teat. A general model explaining the MPC vacuum as the outcome of the balance between air leakage past the mouthpiece lip and the leakage past the teat in the liner barrel is suggested.
A MvaI PCR-RFLP detecting a silent allele at the goat α-lactalbumin locus
Authors: Cosenza Gianfranco , Gallo Daniela , Illario Rosa , di Gregorio Paola , Senese Carmela , Ferrara Lino , Ramunno Luigi
Published: August 2003

Alpha-lactalbumin (α-la), a calcium metalloprotein, is one of the major serum-proteins in ruminant milk (Jenness, 1982) and induces lactose synthesis in the mammary gland by interacting with the enzyme UDP-galactosyltransferase, giving rise to the heterodimer enzyme lactose synthase (Ebner & Brodbeck, 1968; Kuhn, 1983). The goat α-la transcription unit (LALBA), located on chromosome 5 (Hayes et al. 1993), is organized in 4 exons varying in length from 75 nucleotides (3rd exon) to 329 nucleotides (4th exon) coding for a 123-amino acid polypeptide chain (Vilotte et al. 1991). According to the strong similarity between bovine α-la (Vilotte et al. 1987) and human lysozyme (similar molecular weight, the same number of S-S bonds, identical N and C terminal residues; Peters et al. 1989), it has been proposed that both genes arose from a common ancestor (Vilotte et al. 1991).
Effects of α- and β-adrenergic receptor stimulation and oxytocin receptor blockade on milking characteristics in dairy cows before and after removal of the teat sphincter
Authors: Inderwies Tyra , Riedl Johannes , Kiossis Evangelos , Bruckmaier Rupert M.
Published: August 2003

Alpha (α)- and beta (β)-adrenergic receptors in the bovine mammary gland are mainly present in the teat muscles and in the region where large milk ducts reach the cisternal cavities. The aim of the study was to test the hypothesis that the region of the large mammary ducts is the most important location of α- and β-adrenergic receptor stimulation affecting milk ejection and milk removal. Effects of α- and β-adrenergic receptor stimulation and of oxytocin (OT) receptor blockade on milking characteristics were tested in six cows. Milk flow was measured before and after the distal part of one teat, including the teat canal and teat sphincter, had been partly amputated. Before the operation, milk yield and peak flow rate decreased during α-adrenergic receptor stimulation and during the OT receptor blockade, and increased during β-adrenergic stimulation. After removal of the teat tip, relations of milk yield and peak flow rates after administration of α- and β-agonists and after application of an OT receptor blocking agent were similar to those before operation. Only total milk yield had decreased in the teat-amputated quarter owing to unhindered flow of cisternal milk before cluster attachment. Since responses to α- and β-adrenergic receptor stimulation as well as to OT receptor blockade do not differ with or without the teat sphincter, it is concluded that milk flow is mainly influenced by the muscle tone of the large mammary ducts.
Penance and the Market Place: a Reformation Dialogue with the Medieval Church (c. 1250–c. 1600)
Authors: POSTLES DAVE
Published: August 2003

During the later Middle Ages the ecclesiastical jurisdiction generally abandoned ritual humiliation in the market place as an integral part of penance imposed by sentence in its courts, although intermittently this punishment continued into the early sixteenth century. In the early decades of the ecclesia anglicana of Elizabeth, however, several jurisdictions reintroduced shaming in the market place as a consistent part of a disciplinary regime. Although constituting no more than an episode, as public penance had again declined by the 1580s, the reintroduction of penance in the public forum reveals much about the character of the Anglican Church in the first decades after the settlement of 1558, but also reflects back on the pre-Reformation Church.
Diocesan Politics in the See of Worcester 1218–1266
Authors: HOSKIN PHILIPPA M.
Published: August 2003

The two bishops of Worcester between 1218 and 1266, William of Blois and Walter de Cantilupe, were in many ways very similar. Both were dedicated reformers, who made use of the cathedral chapter's churches for their own households for example. Yet their relationships with the monastic chapter of Worcester were very different. William's episcopate was marked by acrimony and dispute, Walter's by harmony and assent. The reasons for these differences are complex but include the personalities and backgrounds of the bishops, the chapter's growing awareness of the limitations of monastic chapters for bishops' patronage and political changes within England.
The Church of Ireland and the Royal Martyr: Regicide and Revolution in Anglican Political Thought c. 1660–c. 1745
Authors: CONNOLLY S. J.
Published: August 2003

The survival in published form of a range of sermons commemorating the execution of Charles I provides an opportunity to examine the character and limits of political debate within the Church of Ireland. After 1688 the task of condemning the regicide of 1649 without seeming to question the legitimacy of the Revolution presented serious difficulties. In the longer term the anniversary ceased to be contentious, as defenders of the Hanoverian establishment appropriated much of the traditional Anglican rhetoric of obedience to lawful authority. That appropriation provides the context for a significant 30 January sermon by Jonathan Swift.
Effective slip in pressure-driven Stokes flow
Authors: LAUGA ERIC , STONE HOWARD A.
Published: August 2003

Nano-bubbles have recently been observed experimentally on smooth hydrophobic surfaces; cracks on a surface can likewise be the site of bubbles when partially wetting fluids are used. Because these bubbles may provide a zero shear stress boundary condition and modify considerably the friction generated by the solid boundary, it is of interest to quantify their influence on pressure-driven flow, with particular attention given to small geometries. We investigate two simple configurations of steady pressure-driven Stokes flow in a circular pipe whose surface contains periodically distributed regions of zero surface shear stress. In the spirit of experimental studies probing slip at solid surfaces, the effective slip length of the resulting flow is evaluated as a function of the degrees of freedom describing the surface heterogeneities, namely the relative width of the no-slip and no-shear stress regions and their distribution along the pipe. Comparison of the model with experimental studies of pressure-driven flow in capillaries and microchannels reporting slip is made and a possible interpretation of the experimental results is offered which is consistent with a large number of distributed slip domains such as nano-size and micron-size nearly flat bubbles coating the solid surface. Further, the possibility is suggested of a shear-dependent effective slip length, and an explanation is proposed for the seemingly paradoxical behaviour of the measured slip length increasing with system size, which is consistent with experimental results to date.
Borders of disorder: in turbulent channel flow
Authors: MALKUS WILLEM V. R.
Published: August 2003

A quantitative theory of the average features of turbulent flow in a channel is described without the introduction of empirical parameters. The qualitative problem consists of maximizing the dissipation rate of the mean flow subject to the Rayleigh condition that the mean flow has no inflections. The quantitative features result from a boundary stability study which determines a smallest scale of motion in the transport of momentum. The velocity fields satisfying these conditions, the averaged equations and the boundary conditions uniquely determine an entire mean velocity profile at all Reynolds numbers within ten per cent of the data. The maximizing condition for the reproducibility of averages emerges from the Navier–Stokes equations as a consequence of a novel definition of nonlinear instability. The smallest scale of motion results from a theory for a time-dependent re-stabilization of the boundary layer following a disruptive instability. Computer reassessment of the several asymptotic estimates of the critical boundary eigenstructure can establish the limits of validity of the quantitative results.
Non-circular baroclinic beta-plane modons: constructing stationary solutions
Authors: KIZNER Z. , BERSON D. , KHVOLES R.
Published: August 2003

Conditions determining the existence of localized steadily translating two-layer vortices (modons) of arbitrary symmetric form on the $\beta$-plane are considered. A numerical method for direct construction of modon solutions is suggested and its accuracy is analysed in relation to the parameters of the computational procedure and the geometrical and physical parameters of the modon sought. Using this method, several non-circular baroclinic solutions are constructed marked by nonlinearity of the dependence of the potential vorticity (PV) on the streamfunction in the trapped-fluid area of the modon, i.e. where the streamlines are closed. The linearity of this dependence and the circularity of the trapped-fluid area are shown to be equivalent properties of a modon. Special attention is given to elliptical modons – extended both in the direction of the modon propagation and in the orthogonal direction, the baroclinic PV component being assumed continuous. The differences between the two types of elliptical modons are discussed. The simplest vortical couples and shielded modons are considered. In the context of the continuity of the baroclinic PV field, the stability of modons is discussed based on numerical simulations.
Structure of a screeching rectangular jet: a stereoscopic particle image velocimetry study
Authors: ALKISLAR MEHMET B. , KROTHAPALLI ANJANEYULU , LOURENCO LUIZ M.
Published: August 2003

The unsteady velocity field generated by an underexpanded jet has been investigated using stereoscopic particle image velocimetry (PIV). A 4:1 aspect ratio converging–diverging rectangular nozzle designed to operate at a fully expanded condition of $M=1.44$ was used. The nozzle was operated at off-design conditions to generate imperfectly expanded jets with intense screech tones. Phase-locked PIV measurements show the spatial and temporal evolution of the three-dimensional jet with high fidelity. In addition to the globally averaged mean and turbulence velocity field data, the phase-averaged data for the velocity and vorticity fields were also obtained. The turbulence quantities were resolved into contributions from the periodic and random motions. The deformation of the periodic spanwise structures results in the formation of strong streamwise vortices that appear to govern the mixing of the jet. It is shown that the presence of coherent vorticity of significant strength, in addition to the shock cell strength, is largely responsible for determining the screech intensity.
The influence of surface tension on the circular hydraulic jump
Authors: BUSH JOHN W. M. , ARISTOFF JEFFREY M.
Published: August 2003

We present the results of a combined theoretical and experimental investigation of the influence of surface tension $\sigma$ on the laminar circular hydraulic jump. An expression is deduced for the magnitude of the radial curvature force per unit length along a circular jump, $F_c\,{=}\,{-}\sigma ( s - \uDelta R )/R_j$, where $R_j$ is the jump radius, and $s$ and $\uDelta R$ are, respectively, the arclength along the jump surface and radial distance between the nearest points at the nose and tail of the jump at which the surface is horizontal. This curvature force is dynamically significant when $2\sigma/(\rho g R_j \uDelta H)$ becomes appreciable, where $\uDelta H$ is the jump height, $\rho$ the fluid density and $g$ the acceleration due to gravity. The theory of viscous hydraulic jumps (Watson 1964) is extended through inclusion of the curvature force, and yields a new prediction for the radius of circular hydraulic jumps. Our experimental investigation demonstrates that the surface tension correction is generally small in laboratory settings, but appreciable for jumps of small radius and height.