bluuebunny/crossref_metadata_2025 huggingface dataset:
Personalist Politics, Clientelism and Citizenship: Local Elections in El Alto, Bolivia
Authors: Lazar Sian
Published: March 2004

The article investigates the citizenship practices of urban Aymara in a neighbourhood of El Alto, Bolivia, through an examination of the municipal elections of December 1999. Using ethnographic methods, I focus on the instrumental and affective sides of clientelism, a central feature of Bolivian elections. I argue that clientelism is a part of citizenship practice, a means of engaging with the state in the person of the politician. A majority of the Bolivian population are marginalised from the oligarchic mestizo system of government, as represented by the traditional political parties. However, at local level, and especially during election campaigns, there is more permeability, and this article sees clientelism as a set of strategies through which citizens attempt to make politics, and politicians, more representative and responsive.
Multisectoral Networks in Global Governance: Towards a Pluralistic System of Accountability
Authors: Benner Thorsten , Reinicke Wolfgang H. , Witte Jan Martin
Published: March 2004

This paper outlines the elements of a pluralistic system of accountability with regard to one of the most ambitious institutional innovations in global governance: multisectoral public policy networks. These networks bring together the public sector (governments and international organizations), civil society and business around issues ranging from corruption, climate change and fighting malaria to environmental and labour standards. We argue that multisectoral networks should be embedded in a pluralistic system of accountability making use of a combination of accountability mechanisms on a number of dimensions (actors, process, outcomes). The paper discusses some of the key conceptual, empirical and practical challenges of a ‘learning model’ of accountability in networks.
Civil Society and Democratically Accountable Global Governance
Authors: Scholte Jan Aart
Published: March 2004

This article explores the ways and extents that civil society associations can bring greater public accountability to global governance. The analysis first reviews the growth of civil society engagement of global governance. Second, the article elaborates four general ways that civil society associations have promoted increased accountability in global governance: by increasing the public transparency of global governance operations; by monitoring and reviewing global policies; by seeking redress for mistakes and harms attributable to global regulatory bodies; and by advancing the creation of formal accountability mechanisms for global governance. Third, the article identifies six broad circumstances that have affected (and often limited) the extent of civil society achievements with respect to accountability in global governance.
Transnational Corporations and Public Accountability
Authors: Koenig-Archibugi Mathias
Published: March 2004

This article considers the issue of public accountability of transnational corporations (TNCs) in the light of the experiences of the past 30 years. It discusses the problem of accountability of corporations in general and examines the accountability gaps that are particularly severe as a result of the global reach and power of TNCs, notably those related to the collusion between government officials and TNCs, to regulatory competition, to state weakness and breakdown, and to political subversion. Then existing attempts to close those gaps are assessed, including intergovernmental cooperation, business ‘self-regulation’ and initiatives that involve nongovernmental organizations and supranational agencies in defining standards of conduct for companies and monitoring their compliance.
Global Governance and Legitimacy Problems
Authors: Zürn Michael
Published: March 2004

Whereas traditional institutions used to be seen as an international complement to a dominantly national paradigm, today's international institutions are an expression of political denationalization. The new international institutions are much more intrusive into national societies than the traditional ones. They increasingly contain supranational and transnational features and thus undermine the consensus principle of international cooperation. When society and political actors begin to comprehend this change, they begin to reflect on the features of a legitimate and effective political order beyond national borders. As a result, denationalization becomes reflexive and thus politicized. At the same time, the politicization of international politics harbours the potential for resistance to political denationalization, which increases the need – both from a normative and descriptive perspective – for the legitimation of such international institutions.
Global Governance and Communicative Action
Authors: Risse Thomas
Published: March 2004

This article discusses arguing and communicative action as a significant tool for non-hierarchical steering modes in global governance. Arguing is based on a logic of action that differs significantly from both the rational choice-based ‘logic of consequentialism’, and from the ‘logic of appropriateness’ theorized by sociological institutionalism. Arguing constitutes a learning mechanism by which actors acquire new information, evaluate their interests in light of new empirical and moral knowledge, and – most importantly – can reflexively and collectively assess the validity claims of norms and standards of appropriate behaviour. As a result, arguing and persuasion constitute tools of ‘soft steering’ that might improve both the legitimacy problems of global governance by providing voice opportunities to various stakeholders and the problem-solving capacity of governance institutions through deliberation.
Democratic Accountability and Political Effectiveness from a Cosmopolitan Perspective
Authors: Held David
Published: March 2004

From the destruction of the twin towers on 11 September 2001 to the failure of trade discussions at Cancún in September 2003, issues are raised that not only concern large swathes of the world's population, but can only be adequately resolved by increased coordination and cooperation across borders. How such coordination and cooperation can be achieved, and how and to whom there should be accountability, are the themes of this article. The article is in six parts. The first part sketches the contemporary nature of global politics; the second examines problems and dilemmas of global public policy-making; the third explores how global governance can be strengthened; the fourth sets out the framework of a cosmopolitan polity which would place democratic accountability at its centre; the fifth unfolds a related concept of multilayered citizenship; and the final part explores the underlying cosmopolitan principles of the argument.
Ergonomic Pain—Part 1: Etiology, Epidemiology, and Prevention
Authors: Sizer Phillip S. , Cook Chad , Brismée Jean‐Michel , Dedrick Leslie , Phelps Valerie
Published: March 2004

Abstract:Work‐related musculoskeletal disorders (MSDs) have reached a costly epidemic proportion in recent years, producing ergonomic pain as their most frequent clinical consequence. While work‐related MSDs have declined in incidence, their prevalence continues. Individuals develop symptoms as a consequence of numerous factors that include force, sustained posture, repetitive motion, and vibration. Different combinations of these factors lend to different pathomechanical and pathophysiological consequences that appear to be unique to different regions of the body and related to distinctive work environmental and task characteristics. Federal and state agencies have made considerable attempts to regulate the work environment in a preventative fashion in order to reduce the incidence of ergonomic pain and other sequelae of work‐related MSDs.
Body composition, age and fertility among free‐ranging female rhesus macaques (Macaca mulatta)
Authors: Campbell Benjamin C. , Gerald Melissa S.
Published: March 2004

Abstract: The relationship of morphometric measures and birth status among 93 females on Cayo Santiago trapped during the 2001 and 2002 seasons was assessed. The proportion of females giving birth differed between the two seasons (0.58 vs. 0.38; P = 0.006) with a prominent decline among older females. Most morphometric measures increased from adolescent to adult groups, but bicep circumference showed a significant decrease among adults. When controlled for age differences, females with infants during the 2002 season exhibited greater bicep circumference, but no difference in abdominal fat than those without. Members of the socially dominant group did not have a higher rate of birth in either 2001 or 2002, despite being significantly longer and weighing more than those of the subordinate group. Abdominal skinfold and bicep circumference were significant predictors of birth status during the 2002 season, controlling for age group, social group membership, and parity in the previous year. Bicep circumference was also a significant predictor of birth status for the 2001 birth season. These findings suggest that individual variation in body composition among females of Cayo Santiago is associated with differences in fertility.
Development of an inexpensive, low attenuation styrofoam primate chair for use in a PET scanner
Authors: Kortekaas R. , van Waarde A. , Maguire R.P. , Leenders K.L. , Elsinga P.H.
Published: March 2004

Abstract:  Pharmacokinetic modelling of radiotracers for positron emission tomography (PET) imaging of neuroreceptors can be performed with time‐activity data for brain and blood. We aimed to develop an alternative to withdrawal of arterial blood samples for acquisition of a blood curve. A supportive primate chair was constructed out of styrofoam and fixed to the head portion of the bed of a PET scanner. A lightly anaesthetised rhesus monkey was positioned in the chair in a sitting position and injected with the radiotracer. The styrofoam chair provided sufficient support for the monkey. The presence of the chair in the PET scanner caused negligible attenuation of radiation, allowing simultaneous acquisition of dynamic data from the subject's brain and heart. We conclude that a styrofoam primate chair is an ideal tool to measure blood and brain data from a rhesus monkey with PET. Invasiveness to the animal is reduced, as well as experimenter time.
Penile vibratory stimulation in the marmoset monkey: a practical alternative to electro‐ejaculation, yielding ejaculates of enhanced quality
Authors: Schneiders A. , Sonksen J. , Hodges J.K.
Published: March 2004

Abstract:  The availability of sufficient amounts of spermatozoa of high quality is one of the main limiting factors in reproductive research and development of reproductive technologies in marmoset monkeys (Callithrix jacchus). Penile vibrostimulation (PVS) has been successfully used in semen collection in the squirrel monkey but with poor success rate in the marmoset. We report here on an improved protocol for PVS with a success rate of almost 90%. Ejaculates obtained by PVS were of enhanced quality compared with those obtained by rectal probe electro‐ejaculation (RPE). PVS ejaculates contained on average three to fourfold higher numbers of total and motile spermatozoa. Assessment of sperm kinematics using computer‐assisted sperm analysis indicated that there are also functional differences between spermatozoa collected by PVS and RPE. Marmoset spermatozoa in samples obtained by RPE swim in a more convoluted manner compared with those obtained by PVS.
Tuberculosis‐like lesions arising from the use of Freund's complete adjuvant in an owl monkey (Aotus sp.)
Authors: Málaga Carlos A. , Weller Richard E. , Roger Broderson J. , Gozalo Alfonso S.
Published: March 2004

Abstract:  An apparently normal, non‐tuberculin‐reacting, splenectomized owl monkey presented tuberculosis‐like lesions of the lung at necropsy. Histological and bacteriological examination failed to demonstrate the presence of acid‐fast organisms. Retrospective inquiry showed the animal had been inoculated using complete Freund's Adjuvant during a malaria vaccine trial. Lesions observed were compatible with lipid embolism of the adjuvant in the lungs.
Suggested mechanisms of action of UVA phototherapy in morphea: a molecular study
Authors: El‐Mofty M. , Mostafa W. , Esmat S. , Youssef R. , Bousseila M. , Nagi N. , Shaker O. , Abouzeid A.
Published: March 2004

Background: Ultraviolet A (UVA) phototherapy proved to be an efficient line of treatment of scleroderma. The mechanism through which it acts is still not clear.

Objective: To detect the mechanism of action of UVA phototherapy in morphea through measuring its effect on the levels of different parameters related to collagen metabolism.

Methods: Twenty‐one cases of morphea were treated with low‐dose broad‐band UVA for 20 sessions. Twelve cases received 20 J/cm2/session with a cumulative dose of 400 J/cm2 and nine cases received 10 J/cm2/session with a cumulative dose of 200 J/cm2. The response was assessed clinically every week. Two skin biopsies were taken from the lesional skin of each patient before starting and after the end of therapy. Paraffin sections were examined for quantitative polymerase chain reaction measurement of collagen I, collagen III, collagenase, transforming growth factor‐beta (TGF‐β) and interferon gamma (IFNγ).

Results: Eighteen patients reported remarkable softening of the skin lesions, with variable degrees ranging from moderate in 57.1% of them good in 19% to very good response in 9.5%. After treatment, all the studied parameters revealed statistically significant changes. There was a significant decrease in collagen I, collagen III and TGF‐β and a significant increase in collagenase (MMP‐1) and IFNγ. The relative change was found to be greatest in collagenase, followed by IFNγ then TGF‐β and finally collagen I. The changes in collagen I, collagenase, IFNγ and TGF‐β were found to increase gradually with the degree of clinical response. In all the parameters studied the relative change was significantly higher in cases treated with 20 J/cm2/session in contrast to those treated with 10 J/cm2/session although no statistically significant difference could be detected in the clinical response to those doses.

Conclusion: The efficacy of low‐dose UVA phototherapy in the treatment of localized scleroderma is mainly obtained by the increased production of MMP‐1 and IFNγ, and to a lesser extent by decreasing TGF‐β and collagen production. Concerning the use of 10 or 20 J/cm2/session those effects are dose dependent, but the clinical response does not significantly differ.
Solar urticaria in Singapore: an uncommon photodermatosis seen in a tertiary dermatology center over a 10‐year period
Authors: Chong Wei‐Sheng , Khoo Shih‐Wee
Published: March 2004

Background: Solar urticaria is an uncommon photodermatosis, characterized by the appearance of pruritic wheals after sun exposure. In this study, we examine the photobiological characteristics of solar urticaria in the heterogeneous group of Singaporean patients.

Methods: The photobiological features of all patients treated for solar urticaria at a tertiary dermatology center in Singapore over a 10‐year period were retrospectively examined.

Results: A total of 19 patients were diagnosed to have solar urticaria from 1993 to 2002. The mean age at diagnosis was 26 years, with a racial distribution of 17 (90%) Chinese, one (5%) Malay, and one (5%) Indian. Fifteen (79%) patients were males and four (21%) were females. The face/neck (47%) and arms/forearms (58%) were most often affected. Six (32%) patients had a history of atopy and two (11%) had dermographism. Fifteen (79%) patients had Fitzpatrick's skin type IV, three (16%) had skin type III and one (5%) patient had skin type V. The mean exposure time to wheal formation was 23 min. The action spectra of solar urticaria were visible light for 12 (63%) patients, ultraviolet (UV) A for one (5%), visible light and UVA for five (27%), and natural sunlight for one (5%) patient. All patients reported partial improvement with a combination of antihistamines and sunscreens as the main modality of treatment.

Conclusion: Our data suggest that solar urticaria is an uncommon photodermatosis and a rare form of urticaria. Wheals were mostly elicited by visible light and/or UVA. A combination of antihistamines and sunscreens provided a useful form of therapy for patients with solar urticaria.
Phototherapy and PUVA photochemotherapy in children
Authors: Holme S. A. , Anstey A. V.
Published: March 2004

The use of phototherapy and photochemotherapy in children has been limited due to concerns over their long‐term carcinogenic potential. Furthermore, the method of administration is disconcerting to some children, particularly as phototherapy treatment units are seldom rendered ‘child‐friendly’. Despite these reservations, ultra‐violet therapies can be useful treatment options for children with selected dermatological conditions provided they are used under carefully controlled conditions.
The characteristics of erythema induced by topical 5‐aminolaevulinic acid photodynamic therapy
Authors: Clark Colin , Dawe Robert S , Moseley Harry , Ferguson James , Ibbotson Sally H.
Published: March 2004

Background: Topical photodynamic therapy (PDT) is increasingly used to treat superficial non‐melanoma skin cancers. Knowledge of the characteristics of 5‐aminolaevulinic acid (ALA)‐induced phototoxicity will increase our understanding of PDT and may facilitate optimisation of treatment regimes.

Methods: We examined the characteristics of ALA‐induced erythema in 10 healthy subjects and investigated the effect of light source and body site.

Results and Conclusion: Maximal erythema occurred within 1–2 h of PDT and inter‐individual variation in ALA‐induced phototoxicity was seen. No detectable differences were seen in the phototoxicity on back or leg sites or between coherent and non‐coherent light sources. These data provide further information to allow us to optimise topical PDT regimes.
Micronucleus evaluation in mitogen‐stimulated lymphocytes of narrow‐band (311 nm TL01) UVB‐treated patients
Authors: Ferahbas Ayten , Donmez‐Altuntas Hamiyet , Hamurcu Zuhal , Aktas Ekrem , Utas Serap
Published: March 2004

Background: Narrow‐band UVB (311 nm) lamps (TL01) are being increasingly used for phototherapy of psoriasis and other dermatoses, for their excellent effect compared with broad‐band UVB sources and photochemotherapy. It is acknowledged that the TL01 lamp is probably two to three times more carcinogenic per minimum erythema dose than broad‐band UVB, but the cumulative dose is considerably less than broadband UVB sources. Micronucleus (MN) test is used to detect both clastogenic (breaking) and aneugenic (abnormal segregation) effect of physical/chemical agents on chromosomes. The aim of this study is to evaluate MN frequencies in mitogen‐stimulated lymphocytes of narrow‐band UVB‐treated patients.

Methods: Frequency of micronuclei in 72 h cultivated/mitogen‐stimulated lymphocytes of 36 patients (age 7–73 years, mean±SD: 25.33±18.54) have been evaluated at pretreatment and after 20, 40, 60 sessions of narrowband UVB treatment.

Results: While the beginning MN frequency ±SD (%) was 1.07±0.63, it increased to 1.47±0.92, 1.47± 0.77, 1.41±0.31 corresponding, respectively, to 20, 40, 60 sessions. These sessions reciprocally correspond to 0.85±0.23, 2.97±0.72, 5.68±1.46 J/cm2 doses of narrow‐band UVB. Difference of MN frequency was statistically significant (P=0.002). Significant differences have been observed between the initial MN frequency and after that of 20, 40, 60 sessions (P=0.001, 0.004, 0.002, respectively).

Conclusion: The results of this study show that narrow‐band UVB treatment causes a detectable chromosome damaging effect.
Thermoelastic Instability of Two-Conductor Friction System Including Surface Roughness
Authors: Jang J. Y. , Khonsari M. M.
Published: March 2004

A model is developed to investigate the mechanism of thermoelastic instability (TEI) in tribological components. The model consists of two thermally conducting bodies of finite thickness undergoing sliding contact. Appropriate governing equations are derived to predict the critical speed beyond which the TEI is likely to occur. This model takes into account the surface roughness characteristics of the contacting bodies as well as the thermal contact conductance at the interface. Analytical expressions are provided for the special cases neglecting the disk thickness and the thermal contact conductance. An extensive series of parametric simulations and discussion of the implication of the results are also presented. The simulations show that the difference in material properties and geometry of the two conducting bodies has a pronounced influence on the critical speed. A special case of the model shows that the threshold of TEI critical speed is pushed to a much higher level when the conducting bodies have identical material properties and are geometrically symmetric. It is also shown that the perturbed wave generally tends to move with the body with higher thermal conductivity.
Nonlinear Transient Response of Thermally Loaded Laminated Panels1
Authors: Oguamanam D. C. D. , Hansen J. S. , Heppler G. R.
Published: March 2004

The nonlinear response of a composite laminated panel that is suddenly exposed to a heat flux is examined using the finite element method. The panel is cantilevered onto a rigid hub, the rotation motion of which is either fully or partially restrained. The panel elastic deformations are assumed large and are modeled via the von Ka´rma´n strain-displacement relationship while the rigid-body angular rotation, for the case of a rotating rigid hub, is assumed small. The system of nonlinear governing equations is solved by the Newton-Raphson method in conjunction with the Newmark time integration scheme. The panel deformation is observed to be sensitive to the motion of the base.
Aeroelastic Flutter Mechanisms of a Flexible Disk Rotating in an Enclosed Compressible Fluid
Authors: Kang Namcheol , Raman Arvind
Published: March 2004

The aeroelastic stability of a thin, flexible disk rotating in an enclosed compressible fluid is investigated analytically through a discretization of the field equations of a rotating Kirchhoff plate coupled to the acoustic oscillations of the surrounding fluid. The discretization procedure exploits Green’s theorem and exposes two different gyroscopic effects underpinning the coupled system dynamics: One describes the gyroscopic coupling between the disk and acoustic oscillations, and another arises from the disk rotation. The discretized dynamical system is cast in the compact form of a classical gyroscopic system and acoustic and disk mode coupling rules are derived. For the undamped system, coupled structure-acoustic traveling waves can destabilize through mode coalescence leading to flutter instability. A detailed investigation of the effects of dissipation arising from acoustic and disk damping predicts previously unknown instability mechanisms for this system. The results are expected to be relevant for the design of high speed, low vibration, low-noise hard disk drives, and optical data storage systems.
Reciprocity Theorems for Diffusion, Flow, and Waves
Authors: Wapenaar and Kees , Fokkema Jacob
Published: March 2004

Diffusion, flow, and wave phenomena can each be captured by a unified differential equation in matrix-vector form. This equation forms the basis for the derivation of unified reciprocity theorems for diffusion, flow and wave phenomena.
Flutter of Rotating Shells With a Co-rotating Axial Flow1
Authors: Cortelezzi L. , Pong A. , Paı¨doussis M. P.
Published: March 2004

It is shown that, in certain regions of parameter space, travelling wave solutions in rotating shells containing co-rotating inviscid fluid become indeterminate. This may render the determination of the flutter speed impossible, or the solution nonphysical.
Nonlinear Elasticity
for Modeling Fracture of Isotropic Brittle Solids
Authors: Volokh K. Y.
Published: March 2004

A softening hyperelastic continuum model is proposed for analysis of brittle fracture. Isotropic material is characterized by two standard parameters—shear and bulk modulus—and an additional parameter of the volumetric separation work. The model can be considered as a volumetric generalization of the concept of the cohesive surface. The meaning of the proposed constitutive equations is clarified by the examples of simple shear and hydrostatic pressure. It is emphasized that the proposed constitutive model includes only smooth functions and the necessary computational techniques are those of nonlinear elasticity.
A Geometrically Nonlinear Shear Deformation Theory for Composite Shells
Authors: Yu Wenbin , Hodges Dewey H.
Published: March 2004

A geometrically nonlinear shear deformation theory has been developed for elastic shells to accommodate a constitutive model suitable for composite shells when modeled as a two-dimensional continuum. A complete set of kinematical and intrinsic equilibrium equations are derived for shells undergoing large displacements and rotations but with small, two-dimensional, generalized strains. The large rotation is represented by the general finite rotation of a frame embedded in the undeformed configuration, of which one axis is along the normal line. The unit vector along the normal line of the undeformed reference surface is not in general normal to the deformed reference surface because of transverse shear. It is shown that the rotation of the frame about the normal line is not zero and that it can be expressed in terms of other global deformation variables. Based on a generalized constitutive model obtained from an asymptotic dimensional reduction from the three-dimensional energy, and in the form of a Reissner-Mindlin type theory, a set of intrinsic equilibrium equations and boundary conditions follow. It is shown that only five equilibrium equations can be derived in this manner because the component of virtual rotation about the normal is not independent. It is shown, however, that these equilibrium equations contain terms that cannot be obtained without the use of all three components of the finite rotation vector.
Nanoscale Domain Stability in Organic Monolayers on Metals
Authors: Suo Z. , Gao Y. F. , Scoles G.
Published: March 2004

Certain organic molecules, such as alkanethiols, can adsorb on metals to form monolayers. Sometimes domains appear in the monolayers. For example, an incomplete monolayer may form islands, and a mixed-composition monolayer may separate into distinct phases. During annealing, the molecules diffuse on the metal surface. The domain boundary energy drives the domains to coarsen. The contact potential between the dissimilar domains drives the domains to refine. On the basis of existing experimental information, we suggest that the competition between coarsening and refining should stabilize certain domain patterns. We formulate a free energy functional to include the effects of mixed species, domain boundary, and contact potential. An approximate energy minimization estimates the equilibrium domain size. We derive a diffusion equation consistent with the free energy functional. The numerical solution of the diffusion equation follows the evolution of the monolayers from a random initial concentration field to patterns of dots and stripes. We also discuss the practical implications of the theory and, in particular, the possibility of guided self-assembly.
Elasticity Solutions Versus Asymptotic Sectional Analysis of Homogeneous, Isotropic, Prismatic Beams
Authors: Yu Wenbin , Hodges Dewey H.
Published: March 2004

The original three-dimensional elasticity problem of isotropic prismatic beams has been solved analytically by the variational asymptotic method (VAM). The resulting classical model (Euler-Bernoulli-like) is the same as the superposition of elasticity solutions of extension, Saint-Venant torsion, and pure bending in two orthogonal directions. The resulting refined model (Timoshenko-like) is the same as the superposition of elasticity solutions of extension, Saint-Venant torsion, and both bending and transverse shear in two orthogonal directions. The fact that the VAM can reproduce results from the theory of elasticity proves that two-dimensional finite-element-based cross-sectional analyses using the VAM, such as the variational asymptotic beam sectional analysis (VABS), have a solid mathematical foundation. One is thus able to reproduce numerically with VABS the same results for this problem as one obtains from three-dimensional elasticity, but with orders of magnitude less computational cost relative to three-dimensional finite elements.
Direct Computational Simulations for Internal Condensing Flows and Results on Attainability/Stability of Steady Solutions, Their Intrinsic Waviness, and Their Noise Sensitivity
Authors: Narain A. , Liang Q. , Yu G. , Wang X.
Published: March 2004

The paper presents a new two-dimensional computational approach and results for laminar/laminar internal condensing flows. Accurate numerical solutions of the full governing equations are presented for steady and unsteady film condensation flows on a sidewall inside a vertical channel. It is found that exit conditions and noise sensitivity are important. Even for stable steady solutions obtained for nearly incompressible vapor phase flows associated with unconstrained exit conditions, the noise sensitivity to the condensing surface’s minuscule transverse vibrations is high. The structure of waves, the underlying characteristics, and the “growth/damping rates” for the disturbances are discussed. A resonance condition for high “growth rates” is proposed and its efficacy in significantly enhancing wave motion and heat transfer rates is computationally demonstrated. For the unconstrained exit cases, the results make possible a separately reported study of the effects of shear, gravity, and surface tension on noise sensitive stable solutions.
Coupled Belt-Pulley Vibration in Serpentine Drives With Belt Bending Stiffness
Authors: Kong Lingyuan , Parker Robert G.
Published: March 2004

A method is developed to evaluate the natural frequencies and vibration modes of serpentine belt drives where the belt is modeled as a moving beam with bending stiffness. Inclusion of bending stiffness leads to belt-pulley coupling not captured in moving string models. New dynamic characteristics of the system induced by belt bending stiffness are investigated. The belt-pulley coupling is studied through the evolution of the vibration modes. When the belt-pulley coupling is strong, the dynamic behavior of the system is quite different from that of the string model where there is no such coupling. The effects of major design variables on the system are discussed. The spatial discretization can be used to solve other hybrid continuous/discrete eigenvalue problems.
Existence of Critical Wavelength for Gap Nucleation in Solidification on a Rigid Mold
Authors: Yigit Faruk
Published: March 2004

Previous theoretical models of pure metal solidification on a patterned mold surface neglected either the thermal capacitance of the solidifying shell material (which is equivalent to assume that thermal diffusivity is infinitely large) or interfacial coupling between the thermal and mechanical fields along the mold-shell interface. In the present work, however, we examine the combined effects of thermomechanical coupling at the mold-shell interface and non-negligible thermal capacitance (or finite thermal diffusivity) of the solidifying shell material during solidification of pure aluminum and iron shells on a rigid, perfectly conducting mold. It is assumed that the mold surface has a sinusoidal corrugation with a small aspect ratio, and the surface is perfectly wet by the molten metal which is initially at its melting temperature. The undulatory geometry of the mold surface lead to nonuniform heat extraction and hence initiated a nonuniform evolving distortion of the metal shell. This distortion produces a critical wavelength that corresponds to the situation where both the contact pressure and its time derivative simultaneously fall to zero. This critical mold surface wavelength serves as a cutoff between those wavelengths that lead to gap nucleation in the troughs and those that lead to gap nucleation in the crests. The conditions for gap nucleation in the mold surface troughs are examined since a corresponding increase in contact pressure at the crests signals the possibility of a growth instability in the metal shell at later stages in the process. Gap nucleation times, associated mean shell thicknesses, and critical wavelengths are calculated for pure aluminum and pure iron shells under identical process conditions. It is found that the iron shell nucleates gaps faster than an aluminum shell, with the associated critical wavelengths of iron being substantially larger than those for aluminum.
Complete Genomic Sequence of the Virulent
Salmonella
Bacteriophage SP6
Authors: Dobbins Aleisha T. , George Matthew , Basham Daryl A. , Ford Michael E. , Houtz Jennifer M. , Pedulla Marisa L. , Lawrence Jeffrey G. , Hatfull Graham F. , Hendrix Roger W.
Published: March 2004

We report the complete genome sequence of enterobacteriophage SP6, which infects
Salmonella enterica
serovar Typhimurium. The genome contains 43,769 bp, including a 174-bp direct terminal repeat. The gene content and organization clearly place SP6 in the coliphage T7 group of phages, but there is ∼5 kb at the right end of the genome that is not present in other members of the group, and the homologues of T7 genes
1.3
through
3
appear to have undergone an unusual reorganization. Sequence analysis identified 10 putative promoters for the SP6-encoded RNA polymerase and seven putative rho-independent terminators. The terminator following the gene encoding the major capsid subunit has a termination efficiency of about 50% with the SP6-encoded RNA polymerase. Phylogenetic analysis of phages related to SP6 provided clear evidence for horizontal exchange of sequences in the ancestry of these phages and clearly demarcated exchange boundaries; one of the recombination joints lies within the coding region for a phage exonuclease. Bioinformatic analysis of the SP6 sequence strongly suggested that DNA replication occurs in large part through a bidirectional mechanism, possibly with circular intermediates.
Transcriptional Analysis of Butanol Stress and Tolerance in
Clostridium acetobutylicum
Authors: Tomas Christopher A. , Beamish Jeffrey , Papoutsakis Eleftherios T.
Published: March 2004

The effects of challenges with low (0.25%, vol/vol) and high (0.75%) concentrations of butanol on the growth, glucose metabolism, product formation, and transcriptional program of the solvent-tolerant
Clostridium acetobutylicum
strain 824(pGROE1) and the plasmid control strain 824(pSOS95del) were used to study solvent tolerance and stress response. Strain 824(pGROE1) was generated by
groESL
overexpression. The growth of 824(pGROE1) was less inhibited than that of 824(pSOS95del), and 824(pGROE1) was able to metabolize glucose over the entire course of the culture (60 h postchallenge) while glucose metabolism in 824(pSOS95del) lasted 24 h. A comparison of their respective DNA array-based transcriptional profiles identified genes with similar expression patterns (these genes are likely to be part of a general butanol stress response) and genes with opposite expression patterns (these genes are likely to be associated with increased tolerance to butanol). Both strains exhibited a butanol dose-dependent increase in expression of all major stress protein genes, including
groES
,
dnaKJ
,
hsp18
, and
hsp90
; all major solvent formation genes, including
aad
,
ctfA
and -
B
,
adc
, and
bdhA
and -
B
(an unexpected and counterintuitive finding); the butyrate formation genes (
ptb
and
buk
); the butyryl coenzyme A biosynthesis operon genes; fructose bisphosphate aldolase; and a gene with homology to
Bacillus subtilis kinA
. A dose-dependent decrease in expression was observed for the genes of the major fatty acid synthesis operon (also an unexpected and counterintuitive finding), several glycolytic genes, and a few sporulation genes. Genes with opposite expression kinetics included
rlpA
,
artP
, and a gene encoding a hemin permease. Taken together, these data suggest that stress, even when it derives from the solvent product itself, triggers the induction of the solvent formation genes.
DNA Sequence Duplication in
Rhodobacter sphaeroides
2.4.1: Evidence of an Ancient Partnership between Chromosomes I and II
Authors: Choudhary Madhusudan , Fu Yun-Xin , Mackenzie Chris , Kaplan Samuel
Published: March 2004

The complex genome of
Rhodobacter sphaeroides
2.4.1, composed of chromosomes I (CI) and II (CII), has been sequenced and assembled. We present data demonstrating that the
R. sphaeroides
genome possesses an extensive amount of exact DNA sequence duplication, 111 kb or ∼2.7% of the total chromosomal DNA. The chromosomal DNA sequence duplications were aligned to each other by using MUMmer. Frequency and size distribution analyses of the exact DNA duplications revealed that the interchromosomal duplications occurred prior to the intrachromosomal duplications. Most of the DNA sequence duplications in the
R. sphaeroides
genome occurred early in species history, whereas more recent sequence duplications are rarely found. To uncover the history of gene duplications in the
R. sphaeroides
genome, 44 gene duplications were sampled and then analyzed for DNA sequence similarity against orthologous DNA sequences. Phylogenetic analysis revealed that ∼80% of the total gene duplications examined displayed type A phylogenetic relationships; i.e., one copy of each member of a duplicate pair was more similar to its orthologue, found in a species closely related to
R. sphaeroides
, than to its duplicate, counterpart allele. The data reported here demonstrate that a massive level of gene duplications occurred prior to the origin of the
R. sphaeroides
2.4.1 lineage. These findings lead to the conclusion that there is an ancient partnership between CI and CII of
R. sphaeroides
2.4.1.
Transcriptional Activation byBacillus subtilisResD: Tandem Binding to Target Elements and Phosphorylation-Dependent and -Independent Transcriptional Activation
Authors: Geng Hao , Nakano Shunji , Nakano Michiko M.
Published: March 2004

The expression of genes involved in nitrate respiration inBacillus subtilisis regulated by the ResD-ResE two-component signal transduction system. The membrane-bound ResE sensor kinase perceives a redox-related signal(s) and phosphorylates the cognate response regulator ResD, which enables interaction of ResD with ResD-dependent promoters to activate transcription. Hydroxyl radical footprinting analysis revealed that ResD tandemly binds to the −41 to −83 region ofhmpand the −46 to −92 region ofnasD. In vitro runoff transcription experiments showed that ResD is necessary and sufficient to activate transcription of the ResDE regulon. Although phosphorylation of ResD by ResE kinase greatly stimulated transcription, unphosphorylated ResD, as well as ResD with a phosphorylation site (Asp57) mutation, was able to activate transcription at a low level. The D57A mutant was shown to retain the activity in vivo to induce transcription of the ResDE regulon in response to oxygen limitation, suggesting that ResD itself, in addition to its activation through phosphorylation-mediated conformation change, senses oxygen limitation via an unknown mechanism leading to anaerobic gene activation.
Agrobacterium-Mediated Transformation ofAspergillus awamoriin the Absence of Full-Length VirD2, VirC2, or VirE2 Leads to Insertion of Aberrant T-DNA Structures
Authors: Michielse Caroline B. , Ram Arthur F. J. , Hooykaas Paul J. J. , van den Hondel Cees A. M. J. J.
Published: March 2004

Reductions to 2, 5, and 42% of the wild-type transformation efficiency were found whenAgrobacteriummutants carrying transposon insertions invirD2,virC2, andvirE2, respectively, were used to transformAspergillus awamori. The structures of the T-DNAs integrated into the host genome by these mutants were analyzed by Southern and sequence analyses. The T-DNAs of transformants obtained with thevirE2mutant had left-border truncations, whereas those obtained with thevirD2mutant had truncated right ends. From this analysis, it was concluded that the virulence proteins VirD2 and VirE2 are required for full-length T-DNA integration and that these proteins play a role in protecting the right and left T-DNA borders, respectively. Multicopy and truncated T-DNA structures were detected in the majority of the transformants obtained with thevirC2mutant, indicating that VirC2 plays a role in correct T-DNA processing and is required for single-copy T-DNA integration.
The
fixABCX
Genes in
Rhodospirillum rubrum
Encode a Putative Membrane Complex Participating in Electron Transfer to Nitrogenase
Authors: Edgren Tomas , Nordlund Stefan
Published: March 2004

In our efforts to identify the components participating in electron transport to nitrogenase in
Rhodospirillum rubrum
, we used mini-Tn
5
mutagenesis followed by metronidazole selection. One of the mutants isolated, SNT-1, exhibited a decreased growth rate and about 25% of the in vivo nitrogenase activity compared to the wild-type values. The in vitro nitrogenase activity was essentially wild type, indicating that the mutation affects electron transport to nitrogenase. Sequencing showed that the Tn
5
insertion is located in a region with a high level of similarity to
fixC
, and extended sequencing revealed additional putative
fix
genes, in the order
fixABCX
. Complementation of SNT-1 with the whole
fix
gene cluster in
trans
restored wild-type nitrogenase activity and growth. Using Western blotting, we demonstrated that expression of
fixA
and
fixB
occurs only under conditions under which nitrogenase also is expressed. SNT-1 was further shown to produce larger amounts of both ribulose 1,5-bisphosphate carboxylase/oxgenase and polyhydroxy alkanoates than the wild type, indicating that the redox status is affected in this mutant. Using Western blotting, we found that FixA and FixB are soluble proteins, whereas FixC most likely is a transmembrane protein. We propose that the
fixABCX
genes encode a membrane protein complex that plays a central role in electron transfer to nitrogenase in
R. rubrum
. Furthermore, we suggest that FixC is the link between nitrogen fixation and the proton motive force generated in the photosynthetic reactions.
Biochemical Characterization of a Dihydromethanopterin Reductase Involved in Tetrahydromethanopterin Biosynthesis in
Methylobacterium extorquens
AM1
Authors: Caccamo Marco A. , Malone Courtney S. , Rasche Madeline E.
Published: March 2004

During growth on one-carbon (C
1
) compounds, the aerobic α-proteobacterium
Methylobacterium extorquens
AM1 synthesizes the tetrahydromethanopterin (H
4
MPT) derivative dephospho-H
4
MPT as a C
1
carrier in addition to tetrahydrofolate. The enzymes involved in dephospho-H
4
MPT biosynthesis have not been identified in bacteria. In archaea, the final step in the proposed pathway of H
4
MPT biosynthesis is the reduction of dihydromethanopterin (H
2
MPT) to H
4
MPT, a reaction analogous to the reaction of the bacterial dihydrofolate reductase. A gene encoding a dihydrofolate reductase homolog has previously been reported for
M. extorquens
and assigned as the putative H
2
MPT reductase gene (
dmrA
). In the present work, we describe the biochemical characterization of H
2
MPT reductase (DmrA), which is encoded by
dmrA
. The gene was expressed with a six-histidine tag in
Escherichia coli
, and the recombinant protein was purified by nickel affinity chromatography and gel filtration. Purified DmrA catalyzed the NAD(P)H-dependent reduction of H
2
MPT with a specific activity of 2.8 μmol of NADPH oxidized per min per mg of protein at 30°C and pH 5.3. Dihydrofolate was not a substrate for DmrA at the physiological pH of 6.8. While the existence of an H
2
MPT reductase has been proposed previously, this is the first biochemical evidence for such an enzyme in any organism, including archaea. Curiously, no DmrA homologs have been identified in the genomes of known methanogenic archaea, suggesting that bacteria and archaea produce two evolutionarily distinct forms of dihydromethanopterin reductase. This may be a consequence of different electron donors, NAD(P)H versus reduced F
420
, used, respectively, in bacteria and methanogenic archaea.
Pleiotropic Effects of Inactivating a Carboxyl-Terminal Protease, CtpA, in
Borrelia burgdorferi
Authors: Östberg Yngve , Carroll James A. , Pinne Marija , Krum Jonathan G. , Rosa Patricia , Bergström Sven
Published: March 2004

A gene encoding a putative carboxyl-terminal protease (CtpA), an unusual type of protease, is present in the
Borrelia burgdorferi
B31 genome. The
B. burgdorferi
CtpA amino acid sequence exhibits similarities to the sequences of the CtpA enzymes of the cyanobacterium
Synechocystis
sp. strain PCC 6803 and higher plants and also exhibits similarities to the sequences of putative CtpA proteins in other bacterial species. Here, we studied the effect of
ctpA
gene inactivation on the
B. burgdorferi
protein expression profile. Total
B. burgdorferi
proteins were separated by two-dimensional gel electrophoresis, and the results revealed that six proteins of the wild type were not detected in the
ctpA
mutant and that nine proteins observed in the
ctpA
mutant were undetectable in the wild type. Immunoblot analysis showed that the integral outer membrane protein P13 was larger and had a more acidic pI in the
ctpA
mutant, which is consistent with the theoretical change in pI for P13 not processed at the carboxyl terminus. Matrix-assisted laser desorption ionization—time of flight data indicated that in addition to P13, the BB0323 protein may serve as a substrate for carboxyl-terminal processing by CtpA. Complementation analysis of the
ctpA
mutant provided strong evidence that the observed effect on proteins depended on inactivation of the
ctpA
gene alone. We show that CtpA in
B. burgdorferi
is involved in the processing of proteins such as P13 and BB0323 and that inactivation of
ctpA
has a pleiotropic effect on borrelial protein synthesis. To our knowledge, this is the first analysis of both a CtpA protease and different substrate proteins in a pathogenic bacterium.
Plasmid Evolution and Interaction between the Plasmid Addiction Stability Systems of Two Related Broad-Host-Range IncQ-Like Plasmids
Authors: Deane Shelly M. , Rawlings Douglas E.
Published: March 2004

Plasmid pTC-F14 contains a plasmid stability system calledpas(plasmid addiction system), which consists of two proteins, a PasA antitoxin and a PasB toxin. This system is closely related to thepasof plasmid pTF-FC2 (81 and 72% amino acid identity for PasA and PasB, respectively) except that thepasof pTF-FC2 contains a third protein, PasC. As both pTC-F14 and pTF-FC2 are highly promiscuous broad-host-range plasmids isolated from bacteria that share a similar ecological niche, the plasmids are likely to encounter each other. We investigated the relative efficiencies of the two stability systems and whether they had evolved apart sufficiently for eachpasto stabilize a plasmid in the presence of the other. The three-component pTF-FC2paswas more efficient at stabilization of a heterologous tester plasmid than the two componentpasof pTC-F14 inEscherichia colihost cells (±92% and ±60% after 100 generations, respectively). The PasA antidote of eachpaswas unable to neutralize the PasB toxin of the other plasmid. Thepasproteins of each plasmid autoregulated their own expression as well as that of thepasof the other plasmid. Thepasof pTF-FC2 was more effective at repressing thepasoperon of pTC-F14 than thepasof pTC-F14 was able to repress itself or thepasof pTF-FC2. This increased efficiency was not due to the PasC of pTF-FC2. The effect of this stronger repression was that pTF-FC2 displaced pTC-F14 when the two plasmids were coresident in the sameE. colihost cell. Plasmid curing resulted in the arrest of cell growth but did not cause cell death, and plasmid stability was not influenced by theE. coli mazEFgenes.