bluuebunny/crossref_metadata_2025 huggingface dataset:
The methylenetetrahydrofolate reductase 677C>T gene polymorphism is not associated with chronic plaque psoriasis
Authors: Weger Wolfgang , Hofer Angelika , Stanger Olaf , Wolf Peter , El‐Shabrawi Yosuf , Renner Wilfried , Kerl Helmut , Salmhofer Wolfgang
Published: March 2008

Background:  Methylenetetrahydrofolate reductase (MTHFR) is involved in the formation of methyl donors, which contribute to DNA methylation. DNA methylation is an essential epigenetic feature playing a critical role in gene regulation and cellular differentiation. In addition, MTHFR activity affects plasma homocysteine levels. A functional polymorphism in the MTHFR gene (677C>T, rs1801133) leading to reduced enzyme activity has been associated with chronic plaque psoriasis in a Chinese population. This finding, however, has not yet been either confirmed or refuted in other populations. The purpose of the present study was to investigate a hypothesized association between the MTHFR 677C>T polymorphism and the presence of chronic plaque psoriasis in a Caucasian population.

Methods:  Genotypes for the MTHFR 677C>T polymorphism were determined in 310 patients and 247 control subjects. In a subgroup of 33 patients and 33 sex‐ and age‐matched control subjects, fasting plasma homocysteine concentrations were determined by high‐performance liquid chromatography and immunological assays were used for the measurement of folate and vitamin B12.

Results:  Prevalence of the homozygous MTHFR 677TT genotype did not significantly differ between patients and controls (15.2% vs 11.7%, P = 0.24). Mean plasma homocysteine concentrations were significantly higher in psoriasis patients than among control subjects (13.5 ± 5.3 μmol/l vs 11.0 ± 2.2 μmol/l, P = 0.026). No significant differences between either mean plasma folate or vitamin B12 concentrations were observed between both groups.

Conclusion:  Our data suggest that the MTHFR 677C>T gene polymorphism is not associated with chronic plaque psoriasis among Caucasians.
Topical isoflavones provide effective photoprotection to skin
Authors: Lin Jing‐Yi , Tournas Joshua A. , Burch James A. , Monteiro‐Riviere Nancy A. , Zielinski Jan
Published: March 2008

Background/purpose: Isoflavones, one main group of phytoestrogens, have antioxidative and photoprotective effects in cellular and mouse studies. The aim of this study is to obtain a more comprehensive understanding of the isoflavone‐mediated photoprotection with the pig skin model, a more human‐resembling model.

Methods: The pig skin was treated with five well‐known isoflavone compounds (genistein, equol, daidzein, biochanin A, and formononetin) and one antioxidant combination solution of 15% vitamin C and 1% vitamin E and 0.5% ferulic acid (CEF) daily for 4 days. Skin was irradiated with solar‐simulated UV irradiation, 1 to 5 minimal erythema dose (MED) at 1‐MED intervals. Evaluation was carried out 24 h later by colorimeter‐measured erythema and sunburn cell numbers.

Results: Topical application of 0.5% solutions of three individual phytoestrogens – genistein, daidzein, biochanin A – are better than similar solutions of equol or formononetin in protecting pig skin from solar‐simulated ultraviolet (SSUV)‐induced photodamage, as measured by sunburn cell formation and/or erythema. However, the protection was less than that provided by a topical combination antioxidant standard containing 15% L‐ascorbic acid, 1%α‐tocopherol, and 0.5% ferulic acid.

Conclusion: Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.
The effect of ultraviolet B‐induced vitamin D levels on host resistance to Mycobacterium tuberculosis: a pilot study in immigrant Asian adults living in the United Kingdom
Authors: Yesudian Paul Devakar , Berry Jacqueline Lesley , Wiles Siouxsie , Hoyle Stefan , Young Douglas Brownlie , Haylett Ann Katarina , Rhodes Lesley Elizabeth , Davies Peter
Published: March 2008

Asian immigrants to the United Kingdom demonstrate much higher tuberculosis rates than the indigenous population. This is postulated to be because of their low vitamin D levels, consequent upon a combination of diet and their reduced ultraviolet (UV) exposure in the United Kingdom, because vitamin D enhances antimycobacterial activity in in vitro systems. The aim of this study was to examine the relationship between UVB exposure, vitamin D levels and tuberculo‐immunity in Asian immigrants in the United Kingdom. Suberythemal UVB treatments were given to eight subjects on 3 consecutive days, using broadband UVB fluorescent lamps. Blood was sampled for 25‐hydroxyvitamin D (25‐OH D) and whole blood functional assays were performed for antimycobacterial immunity. The mean 25‐OH D level increased from a baseline of 11.23 ng/ml (95% CI 6.7–20.39) to 20.39 ng/ml (95% CI 16.6–20) following UVB treatment, P<0.01. However, no significant change in antimycobacterial immunity occurred following UVB exposure. This pilot study in Asian subjects with good baseline tuberculo‐immunity has not supported a role for UVB‐induced 25‐OH D in the immune response to Mycobacterium tuberculosis.
Effect of ultraviolet adaptation on the ultraviolet absorption spectra of human skin in vivo
Authors: Meinhardt Merve , Krebs Ronald , Anders Angelika , Heinrich Ulrike , Tronnier Hagen
Published: March 2008

Background: The absorption spectrum of human skin provides a basis for the estimation of the possible photobiological impact of ultraviolet (UV) radiation. The optical properties of human skin in the UV spectral range have so far mainly been measured ex vivo due to a lack of an appropriate in vivo technique and the change of optical properties during the course of adaptation to higher UV doses has hardly been addressed.

Methods: We have determined the absorption spectra of human skin in vivo in the wavelength range from 290 to 341 nm in 3 nm steps using laser optoacoustics. In this technique, optical properties are derived from the pressure profile generated by absorbed light energy in the sample. Spectra from the volar and dorsal aspects of the forearm of 20 subjects were compared, i.e. sites with native and various facultative pigmentation.

Results: UV adaptation shows as an increase in absorption coefficients over the entire measured UV range and especially in short‐range UVB. Subject groups with high vs. low UV exposure can be discriminated by analyzing the difference absorption spectra between dorsal and volar aspects of the forearm. No dependence on the subject's phototype was seen in the degree of adaptation.

Conclusion: The difference between native and facultative pigmentation may be explained by the absorption properties of the two prime chromophores responsible for adaptation to higher UV exposure: melanin and keratin. Stronger pigmentation, i.e. a higher melanin concentration, is found as an increase of absorption coefficients over the entire UVA‐II/UVB range. The thickening of the horny layer and accordingly, a higher influence of keratin on the absorption spectra is prominent especially in the UVB region.
Differential membrane compartmentalization of Ret by PTB‐adaptor engagement
Authors: Lundgren T. K. , Luebke Moritz , Stenqvist Anna , Ernfors Patrik
Published: March 2008

Glial cell line‐derived neurotrophic factor family ligands act through the receptor tyrosine kinase Ret, which plays important roles during embryonic development for cell differentiation, survival, and migration. Ret signaling is markedly affected by compartmentalization of receptor complexes into membrane subdomains. Ret can propagate biochemical signaling from within concentrates in cholesterol‐rich membrane microdomains or lipid rafts, or outside such regions, but the mechanisms for, and consequences of, Ret translocation between these membrane compartments remain largely unclear. Here we investigate the interaction of Shc and Frs2 phosphotyrosine‐binding domain‐containing adaptor molecules with Ret and their function in redistributing Ret to specialized membrane compartments. We found that engagement of Ret with the Frs2 adaptor results in an enrichment of Ret in lipid rafts and that signal transduction pathways and chemotaxis responses depend on the integrity of such rafts. The competing Shc adaptor did not promote Ret translocation to equivalent domains, and Shc‐mediated effects were less affected by disruption of lipid rafts. However, by expressing a chimeric Shc protein that localizes to lipid rafts, we showed that biochemical signaling downstream of Ret resembled that of Ret signaling via Frs2. We have identified a previously unknown mechanism in which phosphotyrosine‐binding domain‐containing adaptors, by means of relocating Ret receptor complexes to lipid rafts, segregate diverse signaling and cellular functions mediated by Ret. These results reveal the existence of a novel mechanism that could, by subcellular relocation of Ret, work to amplify ligand gradients during chemotaxis.
Calcite and aragonite distributions in the skeletons of bimineralic bryozoans as revealed by Raman spectroscopy
Authors: Taylor Paul D. , Kudryavtsev Anatoliy B. , Schopf J. William
Published: March 2008

Abstract.Bryozoans are among a diverse range of invertebrates capable of secreting calcium carbonate skeletons. Relatively little is known about biomineralization in bryozoans, despite the importance of understanding biomineralization processes for nanotechnology and the threats imposed by ocean acidification on organisms having calcareous skeletons. Ten species of cheilostome bryozoans that are reported to have bimineralic skeletons of calcite and aragonite are studied here using Raman spectroscopy. This technique allowed identification of the two mineral phases at submicron spatial resolution, allowing the distributions of calcite and aragonite within bryozoan skeletons to be determined with unprecedented precision. Confirming previous findings based on the use of chemical stains, most of the bimineralic species analyzed exhibited a calcitic skeletal framework, composed of basal, vertical, and inner frontal walls, having aragonite deposited subsequently onto the outer surfaces of the frontal walls. In one species (Odontionella cyclops), aragonite formed the superstructure above the autozooids, and in two others, traces of aragonite were detected on the undersides of the frontal shields. Using Raman spectroscopy, it was possible for the first time to determine the mineralogy of small‐scale structures, including orificial rims, condyles and hinge teeth, avicularian pivotal bars and rostra, and ascopore rims and sieve plates. Even when surrounded by aragonitic frontal shields, these structures were found typically to be calcitic, the two exceptions being the aragonitic avicularia ofStylopoma inchoansandO. cyclops. Unexpectedly, the first‐formed part of the basal wall at the distalmost growing edge ofPentapora foliaceawas found to consist mainly of aragonite. This may point to a precursory phase of biomineralization comparable with the unusual mineralogies identified previously in the earliest‐formed skeletons of members of some other invertebrate phyla.
Brooding of pelagic‐type larvae in Ophiopeza spinosa: reproduction and development in a tropical ophiodermatid brittlestar
Authors: Byrne Maria , Cisternas Paula , O'Hara Tim
Published: March 2008

Abstract. Ophiopeza spinosa, a small ophiodermatid ophiuroid, is locally abundant in shallow water rubble habitat at Lizard Island, northern Great Barrier Reef, Australia. This species is a protantric hermaphrodite. The switch from reproduction as a male to a female is progressive, involving a simultaneous hermaphrodite as a transitional stage. Members of O. spinosa brood their young in the respiratory bursae. Cohorts of eggs (280 μm diameter) develop synchronously in the gonad and are spawned as a group into the bursa. Despite non‐pelagic development, the larvae of O. spinosa are a vitellaria type typical of broadcast‐spawning ophiodermatids, providing a link to an ancestral form with a dispersive larva. The vitellaria has prominent ciliary bands and swims in the same manner as pelagic vitellaria. In vitro, the larvae developed to the juvenile stage independent of the parent. There was no evidence of extraembryonic nutrition; a proportion of the maternal provisions were retained through metamorphosis. This is the first ophiuroid known to brood a pelagic‐type vitellaria larva. Juveniles appear to leave the parent at the two‐ to three‐arm segment stage, slightly larger than the newly settled juveniles of ophiodermatids with pelagic vitellariae. The presence of functional larvae in the bursa suggests a recent switch to the incubatory life history in O. spinosa and the possibility of a reversal back to a dispersive life history. O. spinosa have the potential to both brood and broadcast their young.
Role of hyperinflation vs. deflation on dyspnoea in severely to extremely obese subjects
Authors: Romagnoli I. , Laveneziana P. , Clini E. M. , Palange P. , Valli G. , De Blasio F. , Gigliotti F. , Scano G.
Published: March 2008

Aim:  To test the hypothesis that obese individuals may either hyperinflate or deflate the lung when exercising. In both cases breathlessness is an inescapable consequence.

Methods:  Ventilatory variables, end‐expiratory lung volume and end‐inspiratory lung volume, and dyspnoea score (Borg scale) were studied in 20 class II‐III obese subjects and 14 healthy controls during incremental symptom‐limited cycle exercise.

Results:  Ventilation increased with increasing work rate, in obese and in control subjects; most obese subjects had to increase end‐expiratory lung volume to escape from flow limitation; in contrast, like controls, a few subjects deflated the lung on heavy‐to‐peak exercise. Dyspnoea was equal in degree at anaerobic threshold and peak exercise in obese as in control subjects, and in obese who hyperinflated as in those who deflated the lung. In particular, end‐expiratory lung volume at baseline (r = −0.84, P = 0.04) was negatively correlated with changes in Borg score in obese who did not hyperinflate: the lower the former the higher the latter. On the other hand, tidal volume (r = 0.54, P = 0.045) and decrease in inspiratory reserve volume (r = 0.59, P = 0.028) were positively correlated with the Borg score in obese subjects who hyperinflated. No other independent variable correlated with the Borg score.

Conclusions:  We conclude that not all obese subjects had to increase end‐expiratory lung volume on heavy‐to‐peak exercise. Changes in dyspnoea for unit changes in ventilation were similar in obese who did hyperinflate as well as in those who did not, suggesting that the increase in respiratory neural drive, associated with an increase in ventilation, is an important source of dyspnoea in obese as well as in control subjects.
Adaptive landscapes and density‐dependent selection in declining salmonid populations: going beyond numerical responses to human disturbance
Authors: Einum Sigurd , Robertsen Grethe , Fleming Ian A.
Published: March 2008

Theory suggests an important role for population density in shaping adaptive landscapes through density‐dependent selection. Here, we identify five methodological approaches for studying such selection, review the existing empirical evidence for it, and ask whether current declines in abundance can be expected to trigger evolutionary responses in salmonid fishes. Across taxa we find substantial amounts of evidence for population density influencing the location of adaptive peaks for a range of traits, and, in the presence of frequency dependence, changing the shape of selection (stabilizing versus disruptive). For salmonids, biological and theoretical considerations suggest that the optimal value of a number of traits associated with juvenile competitive ability (e.g. egg size, timing of emergence from nests, dominance ability), may depend on population density. For adults, more direct experimental and comparative evidence suggest that secondary sexual traits can be subject to density‐dependent selection. There is also evidence that density affects the frequency‐dependent selection likely responsible for the expression of alternative male reproductive phenotypes in salmon. Less is known however about the role of density in maintaining genetic variation among juveniles. Further efforts are required to elucidate the indirect evolutionary effects of declining population abundances, both in salmonids and in other anthropogenically challenged organisms.
Efficacy of a sonic toothbrush for plaque removal by caregivers in a special needs population
Authors: Day James , Martin Michael D. , Chin Mae
Published: March 2008

Oral hygiene and oral health are a major concern for long‐term‐care facility residents who are unable to care for themselves. In this six‐week study, the efficacy of a sonic toothbrush (Sonicare®) was compared with traditional manual brushing in a setting where hygiene care was provided by caregivers. Evaluations of plaque levels were made at baseline and at 2, 4, and 6 weeks according to the Silness and Löe index. The sonic brush was found to be significantly superior to the manual brush over the trial period (MANCOVA; p = 0.026). Plaque reduction at 6 weeks was found to be 38% with the sonic brush and 6% with the manual brush. The results indicate that the sonic brush may be an effective way to provide improved oral health to nursing home subjects when oral care is caregiver‐provided.
Debating a whistle‐blower protection act for employees of the Government of Canada
Authors: Thomas Paul G.
Published: March 2008

Abstract: Based on the premise that whistle‐blowing is most appropriately regarded as a morally ambiguous activity, this article examines how the Liberal government of Paul Martin came to propose a bill designed to encourage and to protect public servants who disclose serious wrongdoing. Written at the time when Bill C‐11 (the Public Servants Disclosure Protection Act) was still before Parliament, the article argues that the existing administrative policy on internal disclosure was judged prematurely to have failed. The complications of measuring the success of any whistle‐blowing regime are noted. The comparative experience of four countries where whistle‐blower protection laws exist demonstrates that the benefits of such laws in terms of promoting “right‐doing” and correcting wrongdoing have been oversold. The article challenges the predominant view that a new parliamentary agency is necessary to deal with whistle‐blowing. Ultimately, the success of any law will depend less on its detailed provisions and far more on a political and administrative culture in government that supports ethical awareness and responsible behavior.

Sommaire: Fondé sur la prémisse selon laquelle la dénonciation est considérée à juste titre comme me activité moralement ambiguë, le présent article examine la manière dont le gouvernement libéral de Paul Martin en est arrivé a adopter un project de loi visant à encourager et à protéger les functionaries qui dénoncent les fautes sérieuses. Rédigé alors que le project de loi C‐11 (Project de loi sur la protection des fonctionnaires dénonciateurs) était encore divan le Parlement, l'article prétend que la politique administrative existante sur la dénonciation interne a été prématurément accusée d'avoir échoué. Les complications consistant à mesurer le succès de tout régime de dénonciation sont notées. L'expérience comparative de quatre pays où il existe des lois sur la protection des dénonciateurs démontre que les avantages de telles lois en ce qui concerne la promotion des bienfaits et la correction des méfaits ont été exagérés. L'article contest l'opinion prédominante selon laquelle il est nécessaire d'avoir un nouvel organisme parlementaire pour traiter de la dénonciation. En fin de compete, le succès de toute loi dépendra moins de ses dispositions détaillées et beaucoup plus d'une culture politique et administrative au sein du gouvernement qui favorise la prise de conscience éthique et les comportements responsables.
Les enjeux de la privatisation des établissements de détention
Authors: Pelletier Daniel , Robard Éric
Published: March 2008

Sommaire: Le mouvement de privatisation des prisons et des pénitenciers a connu un développement fdgurant dans les pays anglo‐saxons de 1990 à 2000. Depuis, plu‐sieurs administrations publiques, en particulier aux États‐Unis, ont réalisé que les avantages escomptés et annoncés par les grandes corporations du secteur privé n'étaient pas vraiment au rendez‐vous, au point ou on parle actuellement de l'éclate‐ment de la bulle de la privatisation. Le débat est aujourd'hui dominé par les positions extrêmes de l'entreprise privée ‐ qui continue à vanter ses établissements ‐ et des associations de défense de droits civiques et des syndicats, qui adoptent la position opposée. L'examen des recherches empiriques ayant été faites à ce sujet révèle que la majorité des études comparatives présentent des failles méthodologiques importantes qui ne permitting pas d'asseoir la prise de décision sur des bases solides. Il importe donc d'agir avec prudence dans ce secteur fortement influencé par des enjeux politiques, sociaux et communicationnels dont l'ampleur reste encore insoupconnée.

Abstract: From 1990 to 2000, the trend towards the privatization of jails and penitentiaries in Anglo‐Saxon countries grew very rapidly. Since then, several public administrations, particularly in the United States, have come to realize that the benefits anticipated by the big corporations in the sector never actually materialized; in fact, we now talk of the bursting of the privatization bubble. Today, the debate is dominated by the extreme positions taken by private enterprise, which continues to boast about its institutions, and by human and trade‐union rights advocacy associations, which are adopting the opposite position. The review of empirical research on this topic indicates that most comparative studies have significant methodological flaws that undermine the foundations of the decision‐making process. It is therefore important to act with caution in this sector, which is highly influenced by political, social and communicational issues, the magnitude of which is yet unknown.
Pressman/Wildavsky and Bardach: Implementation in the public sector, past, present and future
Authors: Graham Andrew
Published: March 2008

Implementation: How Great Expectations in Washington are Dashed in Oakland: or, why it's amazing that federal programs work at all, this being the saga of the Economic Development Administration as told by two sympathetic observers who seek to build morals on a foundation of ruined hopes. By JEFFREY L. PRESSMAN and AARON WILDAVSKY. Berkeley: University of California Press. 1973, and subsequent editions. Pp. 182.

The Implementation Game: What Happens after a Bill becomes a Law. By EUGENE BARDACH. Cambridge, Mass.: MIT Press. 1977. Pp. x, 323.
La Prise de décision: de l'acteur rationnel à la politique bureaucratique
Authors: Kubina Camille
Published: March 2008

This study identifies the basic frame of reference used by most people when thinking about foreign affairs. It also outlines two alternative frameworks. Each frame of reference is, in effect, a ‘conceptual lens’. By comparing and contrasting the three frameworks, we see what each magnifies, highlights, and reveals as well as what each blurs or neglects.

Essence of Decision: Explaining the Cuban Missile Crisis. (2e‐ édition) Par GRAHAM ALLISON et PHILIP ZELIKOW. New York: Longman. 1999. Pp. 416.
Questions d'intérêt permanent, passager et questions d'actualité dans l'administration publique du Canada: tendances dans Administration publique du Canada au cours de ses cinquante ans (1958–2007)
Authors: Carroll Barbara Wake , Kpessa Michael Whyte
Published: March 2008

Sommaire: Ce numéro de la Revue Administration publique du Canada marque deux jalons: le 50e anniversaire de la Revue et le dernier numéro publié par l'lnstitut d'administration publique du Canada. À cette occasion, nous ne publions pas un « numéro spécial » pour lequel nous aurions commandé des articles particuliers. Nous avons plutôt rassemblé un certain nombre d'articles qui se trouvaient déjà en cous et qui, selon l'avis des rédacteurs, représentaient un apport particulier à l'administration publique du Canada. Cet article d'introduction, ou compte rendu de la rédaction, est une analyse rétrospective du contenu de la Revue. Il semblerait que même s'il y a eu un léger virage vers la politique gouvernementale et une plus grande préoccupation pour l'administration provinciale et locale, 1'APC a maintenu un intérêt constant dans ses domaines fondamentaux qui sont la théorie administrative et les institutions politiques et juridiques. Le contenu est également comparéà celui d'autres revues et également à d'autres analyses de 1'apc. Ce compte rendu est suivi des commentaires d'anciens rédacteurs et rédacteurs associés sur leurs expériences avec la Revue.
Les facteurs contributifs au leadership du Greffier dans la fonction publique du Canada1
Authors: Bourgault Jacques
Published: March 2008

Sommaire: Le titre de Greffier du Conseil privé s'accompagne maintenant d'aurres titres et responsabilités. Plusieurs personnalités différentes ont rempli ces responsabilités. Le leadership du Greffier s'exerce sur une variété de personnages politiques et administratifs de premier plan et dans des circonstances souvent paradoxales: il faut savoir implanter les changements tout en protégeant les conventions constitutionnelles. Cet article veut démontrer que la pratique de ce leadership ne peut être ramenée à la seule maîtrise des techniques relationnelles fournies par l'évolution des approches en leadership. Celles‐ci ne sont pas muruellement exclusives mais se complètent. Le dosage des approches dépend d'abord de l'évolution de la fonction et de ses défis, ce qui renvoie à l'approche des compétences. Enfin, l'article montrera que trois autres facteurs ont influencé la.pratique du leadership: le style de gestion du titulaire, sa reputation et le contexte specifique de l'exercice du leadership (soit la dualité des fonctions, les titulaires au sommet et la concurrence des autres acteurs politiques: chef de cabinet, autres ministres et conseillers spéciaux). L'article comporte quatre parties: le concept de leadership appliqué au secteur public; l'évolution du Bureau du Conseil privé et des fonctions du Greffier; les fondements et instruments du leadership et les facteurs de contexte; et la performance en matière de leadership.

Abstract: The title of clerk of the Privy Council now includes several other roles and responsibilities. These responsibilities are fulfilled by several different individuals. Included within the clerk's leadership, sometimes in circumstances that are paradoxical, are a variety of leading political and administrative figures; it is, therefore, essential for the clerk to implement the needed changes while also protecting the conventions of the Constitution. This article seeks to demonstrate that the practice of this type of leadership goes beyond the simple mastery of relational techniques provided by the evolution of leadership approaches. These are complementary rather than mutually exclusive. The particular blend of leadership approaches depends first on the evolution of duty and its challenges, which relates back to the skills approach. Finally, the article will demonstrate that three other factors influence the practice of leadership: the management style of the incumbent; his or her reputation; and the specific context in which the leadership is practised (i.e., the duality of functions and incumbents at the highest level and the competition from the other political actors—chief of staff, other ministers and special advisers). The article has four parts: the concept of leadership as applied to the public sector; the evolution of the PCO and the duties of the clerk; the fundamentals and instruments of leadership and the contextual factors; and the performance of leadership.
Profiling of the public‐service élite: A demographic and career trajectory survey of deputy and assistant deputy ministers in Canada
Authors: Evans Bryan , Lum Janet , Shields John
Published: March 2008

Abstract: In the summer of 2006, a survey was sent to the 941 senior public administration executives who held the rank and title of deputy minister or assistant deputy minister in the federal, ten provincial and three territorial jurisdictions in Canada. The survey explored, among other variables, age, education, gender, ethno‐racial status, aboriginal background and career trajectory. The response rate to this survey was 43.61 per cent. Obviously those in the deputy/assistant deputy cadre (referred to in this article as the “public‐service élite,” or pse) are important actors in the life of the Canadian state, but relatively little is known about them. The authors report on and analyse the meaning and significance of their findings not only for a Canadian perspective but also, on the value of such research in the broader comparative sense. Their data also allow the examination of various dimensions of representative bureaucracy at the most senior levels in Canada.

Sommaire: Au cours de l'été 2006, un sondage sous forme de questionnaire a été envoyé aux 941 cadres supérieurs de la fonction publique qui occupaient des postes de sous‐ministres ou de sous‐ministres adjoints au gouvernement fédéral, au gouvernement des dix provinces et des trois territoires du Canada. Le sondage portait, entre autres variables, sur l'âge, l'éducation, le sexe, le statut ethno‐racial, les origines autochtones et la trajectoire de carrière. Le taux de réponse à ce sondage a été de 43,61 pour cent. Évidemment, les personnes qui occupent les postes de sous‐ministres et de sous‐ministres adjoints (désignés dans le présent article sous le nom d' «élite de la fonction publique» ou «éfp») sont des acteurs importants dans la vie de l'État canadien, mais on les connaît assez peu. Les auteurs donnent un compte rendu et font une analyse de la signification et de 1'importance des résultats, non seulement pour avoir une perspective canadienne, mais aussi pour voir la valeur d'une telle recherche à des fins de comparaison plus vaste. Leurs données permettent également d'examiner diverses dimensions de la bureaucratie représentative aux niveaux les plus élevés du Canada.
Suboptimum Maximum Likelihood Identification of ARMAX Processes
Authors: Fassois S. D. , Lee J. E.
Published: March 2008

A Suboptimum Maximum Likelihood (SML) method for ARMAX process identification from input-output observations is proposed. The proposed method is based on a quadratic approximation of the asymptotic negative log-likelihood function about an estimated point in the Moving Average parameter subspace, as well as an asymptotic ARX representation and fundamental properties of linear stochastic systems. The proposed method is shown to overcome the main drawbacks of the standard Maximum Likelihood and other alternative approaches by offering a low computational load and effectively circumventing the local extrema/wrong convergence problems and the need for initial guess parameter values. In addition, the consistency of the method is established, its extension to the multiple-input case presented, and, in contrast to most alternative approaches, its stability is mathematically guaranteed. The effectiveness of the proposed method is finally demonstrated through numerical simulations and comparisons with the Maximum Likelihood approach.
Application of Some Parameter Adaptive Control Algorithms in Machining
Authors: Elbestawi M. A. , Mohamed Y. , Liu L.
Published: March 2008

Several parameter adaptive control strategies are applied to the problem of regulating cutting forces in end milling under varying cutting conditions. These strategies are shown, using real time control experiments, to be stable with good performance characteristics. It is also shown that the oscillatory response of the adaptive control (AC) system at low feedrates can be substantially improved using a nonlinear controller. Finally, the effect of cutter flexibility on the AC system response is investigated. It is concluded that a first-order model is adequate to represent the cutting process dynamics for a certain range of cutter stiffness.
A Unified Approach to the Design of Adaptive and Repetitive Controllers for Robotic Manipulators
Authors: Sadegh Nader , Horowitz Roberto , Kao Wei-Wen , Tomizuka Masayoshi
Published: March 2008

A unified approach, based on Lyapunov theory, for synthesis and stability analysis of adaptive and repetitive controllers for mechanical manipulators is presented. This approach utilizes the passivity properties of the manipulator dynamics to derive control laws which guarantee asymptotic trajectory following, without requiring exact knowledge of the manipulator dynamic parameters. The manipulator overall controller consists of a fixed PD action and an adaptive and/or repetitive action for feed-forward compensations. The nonlinear feedforward compensation is adjusted utilizing a linear combination of the tracking velocity and position errors. The repetitive compensator is recommended for tasks in which the desired trajectory is periodic. The repetitive control input is adjusted periodically without requiring knowledge of the explicit structure of the manipulator model. The adaptive compensator, on the other hand, may be used for more general trajectories. However, explicit information regarding the dynamic model structure is required in the parameter adaptation. For discrete time implementations, a hybrid version of the repetitive controller is derived and its global stability is proven. A simulation study is conducted to evaluate the performance of the repetitive controller, and its hybrid version. The hybrid repetitive controller is also implemented in the Berkeley/NSK SCARA type robot arm.
Self-Tuning Control Application to Closed-Loop Servohydraulic Material Testing
Authors: Lee S. R. , Srinivasan K.
Published: March 2008

Extensive reliance on manual controller tuning in closed-loop material testing applications makes such applications good candidates for self-tuning control implementation. The current work deals with the modeling, on-line identification, and self-tuning control of electrohydraulic servomechanisms used for closed-loop control of stroke, load, or strain involving low signal frequencies. The application to load and strain control results in servovalve operation close to null and increases the significance of nonideal aspects of servovalve operation such as valve mechanical null offset, valve overlap and radial clearance. Modifications in process modeling and on-line identification necessary to accommodate these aspects are described and shown to be effective by simulation and experiment. A pole-placement controller design approach is used for controller adaptation, the control algorithm being chosen based on analysis of robustness of the control system. The self-tuning control system is shown to be effective, by simulation and experiment.
The Optimal Location of Electromagnets in Multiple Degree-of-Freedom Magnetically Suspended Actuators
Authors: Iwaki S.
Published: March 2008

This paper discusses a systematic design approach to the optimal location of electromagnets in a multiple degree-of-freedom (DOF) magnetically suspended actuator (MSA). An electromagnet location matrix is defined from the geometrical arrangement. Three design conditions for the optimal location are proposed and their criteria are formulated. These conditions are (1) arbitrarily manipulating the controlled body by electromagnets which actuate only in the attractive direction, (2) mechanically decoupling the linearized MSA dynamics, and (3) being robust against the nonlinearity of electromagnets. Simulation results for a simple 3-DOF model are given to confirm the validity of these conditions. An optimal design for a practical 6-DOF model is also included.
An Output Feedback Pusher Plate Controller for the Penn State Electric Ventricular Assist Device: Stability Analysis
Authors: Tasch U. , Klute G. K. , Geselowitz D. B.
Published: March 2008

The development of an optimal output feedback controller for the Penn State electric ventricular assist device (EVAD) is addressed. The controller is designed to minimize the electric energy consumption of the EVAD, while utilizing the measured pusher plate position as the only feedback signal. The controller incorporates statistical information of the targeted patient population and optimizes the expected value of the system performance. The present paper shows that the optimal output feedback control scheme is asymptotically stable when the EVAD operates in a steady beat rate mode, and bounded-input/bounded-output stable when the beat rate undergoes a transient. Since the EVAD operates in either steady or transient beat rate modes, this optimal control scheme is stable.
Modeling and Control of a Balloon Borne Stabilized Platform
Authors: Chingcuanco A. O. , Lubin P. M. , Meinhold P. R. , Tomizuka M.
Published: March 2008

A balloon borne stabilized platform has been developed for a remotely operated altitude-azimuth pointing of a millimeter wave telescope system. A modeling and controller design of the azimuth point system of the platform is presented. Simulation results show that the system is capable of continuous operation with pointing rms to better than 0.01 deg. Ground testing results show continuous operation with pointing rms to better than 0.02 deg; while results of the first flight from the National Scientific Balloon Facility (NSBF) at Palestine, Texas show pointing rms better than 0.02 deg.
Comparison of Methods for Determining Screw Parameters of Infinitesimal Rigid Body Motion From Position and Velocity Data
Authors: Fenton R. G. , Willgoss R. A.
Published: March 2008

Five methods are outlined in this paper for determining the screw parameters of the instantaneous motion of rigid bodies from given velocity and position data of three noncollinear points. The five methods are compared on the basis of their computational efficiency and accuracy. It is found that the method based on vector algebra is much more efficient computationally than any of the other four methods, but has some limitations of applicability. In terms of accuracy, the methods are equivalent when working with exact data. It is recommended that the method based on vector algebra be used for computing screw parameters from position and velocity data when this computation is performed frequently, as in the case of trajectory planning for robotics application. But method hopping be employed where inexact data are used, employing the method which gives the best speed/accuracy combination.
BONDYN: A Bond Graph Based Simulation Program for Multibody Systems
Authors: Felez J. , Vera C. , San Jose I. , Cacho R.
Published: March 2008

This paper presents the BONDYN program (BONd graph DYNamics) as a procedure for simulating dynamic systems. It is based on bond graph theory and provides a means for treating dynamic systems that simultaneously include various physical domains. The program makes use of the bond graph module handling facility in order to build a general model starting from simple submodels. Although the latter can be defined by the user, a library has been appended to the preprocessor which includes some of these submodels. Special developments for simulating multibody systems can be found among them. Once the overall bond graph has been assembled the program builds the state equations of the system in the form of a subroutine that can be accepted by a high level language compiler, which is FORTRAN 77 in this case. Simulation outputs can be shown either graphically or in a table.
On Modeling of Integrated Communication and Control Systems
Authors: Liou Luen-Woei , Ray Asok
Published: March 2008

In a two-part paper [1,2], Ray and Halevi reported modeling of Integrated Communication and Control Systems (ICCS). Varying and distributed delays are introduced in the control system due to asynchronous time-division multiplexing in the communication network. This correspondence illustrates the relationship of Ray and Halevi’s approach to that of Kalman and Bertram [3] under nonsynchronous sampling.
In Search of Weaker Conditions to Insure Robust Stability in Linear Feedback Systems
Authors: Chait Yossi , Cohen Nir , MacCluer C. R.
Published: March 2008

This paper is concerned with the well-known condition for robust stability of systems with plant uncertainty. It is shown that the usual sufficient condition for robust stability, given in terms of the maximum modulus of the plant approximation error, can be relaxed to a sector condition. This sector condition, related to the phase of the uncertain portion of the plant, can increase the range of the allowed variations in the parameters of the uncertain plant sufficient for robust stability.
Simulation of Flexible-Link Manipulators Applying Sequential Integration Method
Authors: Chang Liang-Wey , Hamilton J. F.
Published: March 2008

The Equivalent Rigid Link System (ERLS) dynamic model offered a complete representation for the dynamics of flexible manipulators. The equations of motion were separated into a nonlinear large motion and a linear small motion. In this paper, a sequential integration method facilitates the solution of the system equations. This method integrates the large (slow) motion equation explicitly and integrates the small (fast) motion equation implicitly. The simulation results are presented to show the computation efficiency and the flexibility effects.
Identification of Fiducial Points in Serial Data
Authors: Auslander D. M. , Griffin J. C. , Mayya A.
Published: March 2008

A method is described for fiducial point identification that can be tuned to specific data types using training set data having manually marked fiducial points. The role of the “expert” in the training process is limited to providing the correct point identification in the training data. No articulation of the mathematical justification for the choice is needed. The method is based on the calculation of a weighted score for each point in an unknown data record. The score is derived from a doubly normalized computation of values for a set of generic discriminant functions. Candidate points are identified by an order and selection process. Because of the multiple normalization and use of sorting for selection, the method is independent of scale or range of the data to be identified. Neither the training process nor the identification process requires any dimensional input, other than the identification of fiducial points for use in the training process. Examples are given using cardiac electrogram data and ultrasonic data.
A Neural Network Truth Maintenance System
Authors: Mounfield W. P. , Guddanti S.
Published: March 2008

A novel approach using neural networks to solve expert system problems is presented in this paper. Facts are represented by neurons and their interconnections form the knowledge base. The Truth Maintenance System neural network arrives at a valid solution provided the solution exists. A valid solution is a consistent set of facts. If the solution does not exist the network limit cycles. An experimental setup was built and tested using conventional integrated circuits. The hardware design is suitable for VLSI implementation for large, real-time problems.
On-Off Decentralized Control of Flexible Structures
Authors: Foster L. A. , Silverberg L.
Published: March 2008

A new near minimum fuel method for on-off decentralized control of flexible structures is introduced. Fuel minimization is achieved by turning on actuators when local velocities are in the neighborhood of a maximum and when local displacements are in the neighborhood of a minimum. Maximum velocity and minimum displacement neighborhoods at each actuator location are determined by recursively computing standard deviations of displacements and velocities over running intervals of time. The fuel consumed by on-off control is shown to be 20 percent lower than by linear optimal control for the same reductions in energy over the same periods of time. On-off control of a uniform beam illustrates the method.
The Kinematics of Robotic Manipulators With Flexible Links Using an Equivalent Rigid Link System (ERLS) Model
Authors: Chang Liang-Wey , Hamilton J. F.
Published: March 2008

The Equivalent Rigid Link System (ERLS) is presented for the analysis of the kinematics of manipulators with flexible links. The concept of the ERLS is to separate the rigid-body dynamics and structural dynamics. The global motion of the flexible-link system is thereby separated into a large motion with a superimposed small motion. The large motion is represented by the ERLS and the small motion is due to the deviations with respect to the ERLS. The complete motion of manipulators is described by homogeneous transformations. The Jacobian and inverse kinematics are also presented in this paper.
Reference Input Generation for High Speed Coordinated Motion of a Two Axis System
Authors: Butler J. , Haack B. , Tomizuka M.
Published: March 2008

A method for generating two-dimensional reference trajectories to be followed by a linear second-order system under feedforward/feedback control is proposed. A differential equation is derived which assigns tracking velocity and tangential tracking acceleration as functions of time in such a way to allow high speed motion through an arbitrary smooth curve while guaranteeing the absence of actuator saturation. A method for using preview information for motion along curves with corners is also presented. The results are verified by simulation of a two axis cartesian positioning system under discrete time zero phase error tracking control.
The Effect of Adding Zeroes to Feedforward Controllers
Authors: Haack B. , Tomizuka M.
Published: March 2008

The effect of adding zeroes to two types of feedforward controllers, stable pole zero cancelling (SPZC) controllers and zero phase error tracking (ZPET) contollers, is discussed. When there are uncancellable zeroes in the feedback system, additional zeroes in the feedforward controller can reduce the tracking and/or the contour error. For multi-axis contouring with mismatched axis dynamics, a ZPET controller cancels the phase error and provides good contouring accuracy. With a SPZC controller which does not cancel the phase lag, the axes can be “matched” for equal phase lag by adding zeroes to the feedforward controller.
Design of Nonovershoot MRACS With Application to D.C. Servo Motor System
Authors: Tamura K. , Ogata K. , Nikiforuk P. N.
Published: March 2008

Excessive overshoots in a transient response are undesirable in a model reference adaptive control system (MRACS) and have to be avoided in practical applications. This paper discusses the design of an MRACS with no overshoot. In this design a d-step ahead estimator is introduced to evaluate the expected maximum and minimum values of the plant output. According to these estimates, the adaptive control input is adjusted so that the output has no overshoot. For the estimator and the input adjustment an existence region of the unknown plant parameters must be known. It is obvious that the smaller the existence region is, the better is the estimation and adjustment, and, consequently, the MRACS performance. First, an algorithm which successively reduces the region is presented. An initial polyhedron region V(0), which includes the unknown parameters, assumed to be given. The volume of V(k) containing the unknown parameters is then successively reduced by a projection-type algorithm which uses the input and output of the plant. Next, the design of an MRACS is discussed in which this region V(k) plays an important role. The proposed controller generates an adaptive control input sequence which makes the plant output follow the reference output without any overshoot. The proposed MRACS was applied to the adaptive position control of a D.C. servo motor system with an unknown load. Experimental results demonstrate the usefulness of the proposed design.