bluuebunny/crossref_metadata_2025 huggingface dataset:
A test of Metabolic Theory as the mechanism underlying broad‐scale species‐richness gradients
Authors: Algar Adam C. , Kerr Jeremy T. , Currie David J.
Published: October 2006

Aim  To test whether the temperature dependence of individuals’ metabolic rates is the mechanism shaping broad‐scale species‐richness gradients as proposed in the Metabolic Theory of Ecology recently proposed by Allen, Gillooly and Brown.

Location  North America, north of Mexico.

Methods  Metabolic Theory predicts that the natural logarithm of species richness will be a linear function of environmental temperature ((kT)−1, where k is Boltzmann's constant and T is temperature in K) with a slope of −0.78. We tested these predictions using the broad‐scale variation in richness of amphibians, reptiles, trees, tiger beetles, butterflies and blister beetles. We tested whether the temperature–richness relationship was linear or curvilinear, and determined the range of temperature values (and geographical area) where the instantaneous slope of the curvilinear temperature–richness relationship was statistically indistinguishable from −0.78, after correcting for spatial autocorrelation.

Results  We found that for all taxa, temperature–richness relationships were curvilinear. Moreover, for five of six taxa, the slope of this relationship was close to the predicted value for only a narrow range of temperatures. Blister beetles displayed the widest temperature range that is consistent with the Metabolic Theory, covering 45% of the study's geographical area. For the remaining taxa, the geographical range in which the slope is consistent with the predicted value amounts to only 10–20% of North America.

Main conclusions  For a wide array of taxa in North America, temperature–richness relationships deviate from the pattern predicted by Metabolic Theory. These results demonstrate that the temperature dependence of individuals’ metabolic rates is not the sole cause of broad‐scale diversity gradients. Even in areas where factors other than temperature do not influence productivity, the data do not suggest that richness patterns are determined by the temperature dependence of metabolic rate.
The Poverty Reduction Strategy Approach Six Years On: An Examination of Principles and Practice in Uganda
Authors: Canagarajah Sudharshan , Van Diesen Arthur
Published: October 2006

It is over six years since the World Bank and the IMF started promoting a PRS approach to development management in low‐income countries. The 2005 review endorsed the approach, but highlighted the need for a renewed focus on the principles underpinning it: country ownership; results orientation; comprehensiveness; partnership focus; and long‐term outlook. Uganda is often hailed as one of the best PRS performers. This article finds that Uganda's Poverty Eradicaton Action Plan (PEAP) has brought significant gains to development management, but that its performance against several of the PRS principles is disappointing. A return to these principles could improve the practice of the government and development partners around the PEAP – a finding likely to be applicable to many countries implementing a PRS.
Intellectual Property Rights and Economic Growth
Authors: Falvey Rod , Foster Neil , Greenaway David
Published: October 2006

Interest in links between protection of intellectual property and growth has been revived by developments in new growth theory and by the WTO’s TRIPS Agreement. The relationship between the strength of a country’s intellectual property rights (IPRs) regime and rate of growth is ambiguous from a theoretical standpoint, reflecting the variety of channels through which technology can be acquired and their differing importance at different stages of development. We investigate the impact of IPR protection on economic growth in a panel of 79 countries using threshold regression analysis. We show that whilst the effect of IPR protection on growth depends upon the level of development, it is positively and significantly related to growth for low‐ and high‐income countries, but not for middle‐income countries. This suggests that, although IPR protection encourages innovation in high‐income countries, and technology flows to low‐income countries, middle‐income countries may have offsetting losses from reduced scope for imitation.
Professionalism and whole primary school factors aiding and impeding the work of the Learning Mentor
Authors: MARSHALL HEATHER ROPER
Published: October 2006

This article is based on a survey of 25 learning mentors in order to identify their background and training, barriers and opportunities they experience in their work with individual primary aged pupils with EBD. Heather Roper Marshall undertook this study as part of her work towards her BA (Hons) Education. She adopts a personalised, narrative style to describe the experiences of learning mentors, highlighting the importance of their relationships with the children they support and with other professionals working in primary schools.
THE EMERGENCE OF CENTRALITY IN A TRANSITION ECONOMY: COMPARING LAND MARKET DYNAMICS MEASURED UNDER MONOCENTRIC AND SEMIPARAMETRIC MODELS*
Authors: Redfearn Christian L.
Published: October 2006

ABSTRACT This paper focuses on the emergence of Krakow's historic core as the city's economic center after Poland's economic reforms of 1989—reforms that introduced market forces into land markets. Using a semiparametric approach to identify pricing centers, an evolving and polycentric price surface is revealed. While the traditional city center emerges as the dominant node, the evolution of the price surface is far more complex than that found using alternative approaches. Accordingly, it yields superior explanatory power compared to simpler monocentric models and should caution against their use in metropolitan areas in transition or those that are polycentric.
Haematocrit is weakly related to condition in nestling Barn SwallowsHirundo rustica
Authors: CUERVO JOSÉ J. , MØLLER ANDERS P. , DE LOPE FLORENTINO
Published: October 2006

Currently, there is no agreement about the suitability of haematocrit (the proportion of blood volume occupied by packed red blood cells) as a predictor of condition in birds. In order to clarify this point, genetic and environmental components of phenotypic variation for a number of traits were estimated in nestling Barn SwallowsHirundo rusticaby means of a partial cross‐fostering experiment. The studied traits were haematocrit, two morphological traits used as estimates of condition in birds (body mass and body mass relative to body size) and a morphological trait that presumably is not associated with condition (tarsus length). First, we found that body mass relative to body size was related to haematocrit, supporting the suggestion that haematocrit reflects condition in this species. Secondly, we found that the coefficient of residual (i.e. environmental) variation of haematocrit was larger than that of tarsus length, but smaller than those of body mass or body mass relative to body size. Under the hypothesis that traits closely related to condition (and, ultimately, to fitness) are characterized by large residual variance, these results also suggest that haematocrit is related to condition, but that this relationship must be weak. Therefore, the use of haematocrit as an estimate of condition is not recommended. Finally, heritabilities of the studied traits were calculated, differing significantly from zero only for tarsus length, the trait with the smallest residual variation. However, a consistent pattern in the relationship between heritability and genetic variation was not found.
Subendocardial versus transmural ischaemia in myocardial perfusion SPECT – a Monte Carlo study
Authors: Bartosik Jolanta , El‐Ali Henrik Hussein , Nilsson Ulf , Dahlström Jan , Edenbrandt Lars , Ljungberg Michael
Published: October 2006

Myocardial perfusion imaging with single‐photon emission computed tomography (SPECT) is useful for the evaluation of patients with known or suspected coronary artery disease. Parameters of interest are the reduction in the blood perfusion (severity) and the lesion volume (extent). The aim of this study was to evaluate these parameters, as calculated by automatic quantification software, for different cases of subendocardial and transmural myocardial lesions.

Methods  A computer phantom was used to simulate 32 male patients with different defect locations and activity uptakes, which were based on clinical patient studies. The Monte Carlo program SIMIND was used to simulate realistic SPECT projections which were reconstructed to give short‐axis images, analysed by the AutoQUANT program using the same procedure as for a real patient.

Results  The results showed a disparity between the quantification of transmural and subendocardial lesions with the same lesion activity uptake reduction and this could be confirmed by visual interpretation. Neither the parameters given by the quantification program nor visual interpretation could distinguish between the transmural lesions and the subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions.

Conclusion  Transmural lesions and the corresponding subendocardial lesions with the same activity uptake reduction could be separated by the quantification software for SPECT imaging and visual analysis. The subendocardial lesions with activity uptake reduction twice as high as in the corresponding transmural lesions could not be differentiated neither by the quantification software nor by visual interpretation. Thus these lesions will get the same scoring when analysed by the AutoQUANT program.
Fracture and Ageing in Bone: Toughness and Structural Characterization
Authors: Ritchie R. O. , Nalla R. K. , Kruzic J. J. , Ager J. W. , Balooch G. , Kinney J. H.
Published: October 2006

Abstract:  The development of a mechanistic understanding of the increase in fracture risk in human bone with age is essential to public health. This represents a challenge for fracture mechanics as bone has a complex, hierarchical structure with characteristic features ranging from nanometer to macroscopic dimensions, and is thus much more complex than most engineering materials. In this study, we review ex vivo fracture experiments which quantitatively assess the effect of age on human cortical bone in the proximal–distal orientation, i.e. along the long axis of the bone. Specifically, cortical bone is seen to exhibit rising crack‐growth resistance with crack extension; the toughness is consequently evaluated in terms of R‐curves, measured in bones taken from a wide range of age groups (34–99 years). Both crack‐initiation and crack‐growth toughnesses were determined and were found to deteriorate with age; the initiation toughness decreases some 40% over the 65 years of ageing, while growth toughness is effectively eliminated over the same age range. The reduction in crack‐growth toughness is considered to be associated primarily with a degradation in the degree of extrinsic toughening, in particular involving crack bridging in the wake of the crack. This explanation is supported by an examination of the micro‐/nanostructural changes accompanying the process of ageing, performed using deep‐UV Raman spectroscopy, computed X‐ray tomography and optical/electron microscopy.
The Post‐Yield Behaviour of an Internally Pressurised Cylinder having a Pad Attachment
Authors: Lee K. S. , Moreton D. N. , Bouchard P. J. , Moffat D. G.
Published: October 2006

Abstract:  A study of pressurised cylinders having attached pads was made. The possibility of a fatigue crack developing along one side of the pad was noted. For both defect‐free components and components having axial crack‐like defects, finite element and limited experimental studies of the local and global deformations were made and results were found to be in close agreement. Both welded and integrally machined pads were studied. It was observed that for defect‐free components, the method of pad attachment has little effect on the burst pressure. The presence of a pad was found to increase the burst pressure of cracked components by a small but significant margin. A finite element‐based parametric study of pipes with part‐penetrating defects and a range of pad geometries has demonstrated that pad size has little influence on the limit load for any of the cracked cases considered. However, pipes with penetrating defects were strengthened by the presence of pads, particularly for thin‐walled sections.
Genomics of Brain and Blood: Progress and Pitfalls
Authors: Sharp Frank R , Lit Lisa , Xu Huichun , Apperson Michelle , Walker Wynn , Wong Brenda , Gilbert Donald L. , Hershey Andrew , Glauser Tracy A.
Published: October 2006

Summary:  Gene expression profiles in brain and blood of animals and humans can be useful for diagnosis, prognosis, and treatment of epilepsy. This article reviews recent progress and prospects for the future.
No Association of Single Nucleotide Polymorphisms in the μ‐Opioid Receptor Subunit Gene with Idiopathic Generalized Epilepsy
Authors: Barratt Catherine , Lai Teck , Nashef Lina , Valentin Antonio , Fisniku Leonora , Moran Nicholas , Asherson Philip , Makoff Andrew
Published: October 2006

Summary:  We have investigated the reported association (p = 0.019) between the A118G single nucleotide polymorphism (SNP) of the opioid receptor μ subunit gene (OPRM1) and idiopathic absence epilepsy (IAE). Five SNPs, including A118G, were investigated by association studies in a sample of 240 probands with idiopathic generalized epilepsy (IGE), including 110 with IAE, and 257 controls. No significant association was found for A118G with IGE or IAE. The difference between the two studies was in the control samples that had significantly different allele frequencies (p = 0.00005), suggesting that population stratification may explain the earlier significant association with IAE. In the current study, none of the other four SNPs was significantly associated with IGE or IAE. Our results provide no support for association of A118G with either IAE or IGE and also exclude association in our sample of a small‐to‐moderate gene effect with IGE from a large part of OPRM1.
Can Hip Protector Use Cost‐Effectively Prevent Fractures in Community‐Dwelling Geriatric Populations?
Authors: Honkanen Lisa A. , Mushlin Alvin I. , Lachs Mark , Schackman Bruce R.
Published: October 2006

OBJECTIVES:To estimate the cost‐effectiveness from a societal perspective of a hip protector (HP) program over the remaining lifetime of individuals initially living at home.

DESIGN:A state‐transition Markov model considering outcomes of HP use in cohorts stratified by age, sex, and functional and residential status. Costs, transition probabilities, HP adherence, and efficacy were derived from published sources.

SETTING:Community and nursing homes in the United States.

PARTICIPANTS:Hypothetical cohort of individuals aged 65 and older without a hip fracture and initially living at home.

INTERVENTION:HP program.

MEASUREMENTS:Fractures, life years, and dollars saved, quality‐adjusted life‐years (QALYs), and incremental cost‐effectiveness ratios (ICER).

RESULTS:HP use prevented fractures and increased life expectancy in all cohorts. HP use saved costs and improved QALYs in women initiating HP use at age 80 and in men at age 85. In women initiating HP use at age 75, the HP ICER was $19,000/QALY. In men initiating HP use at age 80, HP use saved costs but slightly decreased QALYs. In younger cohorts, HP use was neither cost saving nor QALY improving. In sensitivity analyses, if there was no QALY loss from wearing a HP, the ICER was less than $50,000/QALY for all age and sex cohorts. If HP cost was reduced 50%, HP use was cost saving for women initiating HP use at age 75. In probabilistic sensitivity analyses, the HP ICER was less than $50,000/QALY in 68% of simulations for women initiating HP use at age 75 and 61% of simulations for men initiating at age 85.

CONCLUSION:HP use saved costs and QALYs for older age cohorts of both sexes. Additional research on the quality‐of‐life effects and obstacles to wearing HP is warranted.
Socioeconomic Status and Survival in Older Patients with Melanoma
Authors: Reyes‐Ortiz Carlos A. , Goodwin James S. , Freeman Jean L. , Kuo Yong‐Fang
Published: October 2006

OBJECTIVES: To determine the association between socioeconomic status (SES) and survival in older patients with melanoma.

DESIGN: Retrospective cohort study.

SETTING: Surveillance, Epidemiology and End Results (SEER): a population‐based cancer registry covering 14% of the U.S. population.

PARTICIPANTS: Twenty‐three thousand sixty‐eight patients aged 65 and older with melanoma between 1988 and 1999.

MEASUREMENTS: Outcome was melanoma‐specific survival. Main independent variable was SES (measured as census tract median household income) taken from the SEER‐Medicare linked data.

RESULTS: Subjects residing in lower‐income areas (≤$30,000/y) had lower 5‐year survival rates (88.5% vs 91.1%, P<.001) than subjects residing in higher‐income areas (>$30,000/y). In Cox proportional hazard models, higher income was associated with lower risk of death from melanoma (hazard ratio=0.88, 95% confidence interval=0.79–0.98, P=.02) after adjusting for sociodemographics, stage at diagnosis, thickness, histology, anatomic site, and comorbidity index. There was an interaction effect between SES and ethnicity and survival from melanoma. For whites and nonwhites (all other ethnic groups), 5‐year survival rates increased as income increased, although the effect was greater for nonwhites (77.6% to 90.1%, 1st to 5th quintiles, P=.01) than for whites (89.0% to 91.9%, 1st to 5th quintiles, P<.001).

CONCLUSION: Older subjects covered by Medicare residing in lower‐SES areas had poorer melanoma survival than those residing in higher‐SES areas. Further research is needed to determine whether low SES is associated with late‐stage disease biology and poorer early detection of melanoma.
The Role of Leader Influence Tactics and Safety Climate in Engaging Employees' Safety Participation
Authors: Clarke Sharon , Ward Katie
Published: October 2006

This study examines the effect of leader influence tactics on employee safety participation in a U.K.‐based manufacturing organization, examining the role of safety climate as a mediator. Structural equation modeling showed that leader influence tactics associated with a transformational leadership style had significant relationships with safety participation that were partially mediated by the safety climate (consultation) or fully mediated by the safety climate (inspirational appeals). In addition, leader influence tactics associated with a transactional leadership style had significant relationships with safety participation: rational persuasion (partially mediated by safety climate) and coalition tactics (direct effect). Thus, leaders may encourage safety participation using a combination of influence tactics, based on rational arguments, involvement in decision making, and generating enthusiasm for safety. The influence of building trust in managers is discussed as an underlying mechanism in this relationship. Practical implications are highlighted, including the design of leadership development programs, which may be particularly suited to high‐reliability organizations.
Vero‐Cytotoxigenic Escherichia coli O157 in Pasteurized Milk Containers at the Point of Retail: A Qualitative Approach to Exposure Assessment
Authors: Clough Helen E. , Clancy Daymian , French Nigel P.
Published: October 2006

Dairies within the United Kingdom are classified into two groups, namely, off‐farm and on‐farm dairies (the latter often being small scale). We propose a model for the probability of milk sold as pasteurized reaching the point of retail contaminated with Vero‐cytotoxigenic Escherichia coli (VTEC) O157 from each of these two pathways. We evaluate qualitatively the exposures inherent in each, and compare and contrast the two situations. The model framework is generic, in that it can in principle be used, with the relevant data modifications, to provide a qualitative assessment of the likely exposure from milk sold as pasteurized to any potentially milk‐borne pathogenic organism. Furthermore, the methodological approaches presented are widely applicable in the microbial risk assessment field. The specific example presented will be of particular interest to the UK dairy and public health communities: we conclude that the exposure potential per liter consumed from milk processed in off‐farm dairies is negligible, whereas the exposure potential per liter consumed from milk processed on‐farm is low, but not sufficiently small to be regarded as negligible. We also identify areas of data sparsity, which need to be addressed for quantitative risk assessment to proceed, and highlight the critical points in the pasteurized milk production chain, which, in the event of a breakdown, have the potential to increase the risk to the consumer.
Molecular Characterization of the Obligate Endosymbiont “Caedibacter macronucleorum”Fokin and Görtz, 1993 and of its Host Paramecium duboscqui Strain Ku4‐8
Authors: SCHRALLHAMMER MARTINA , FOKIN SERGEI I. , SCHLEIFER KARL‐HEINZ , PETRONI GIULIO
Published: October 2006

ABSTRACT. Bacterial endosymbionts of protozoa were often described as new species by protozoologists mainly on the basis of few morphological characters and partly by host specificity. Many of these species have never been validated by prokaryotic microbiologists whose taxonomic rules are quite different from those of protozoologists, who use the Zoological Code of Nomenclature. “Caedibacter macronucleorum”Fokin and Görtz 1993, an endosymbiont of Paramecium duboscqui, belongs to this category. Here we provide the molecular characterization of this organism and of its host P. duboscqui strain Ku4‐8. Bacterial 16S rRNA gene sequence analysis proved that “C. macronucleorum” belongs to the Alphaproteobacteria. It is closely related to Caedibacter caryophilus but not to Caedibacter taeniospiralis, which belongs to the Gammaproteobacteria. “Caedibacter macronucleorum” and C. caryophilus 16S rRNA genes show a similarity value of 99%. This high 16S rRNA sequence similarity and the lack of a specific oligonucleotide probe for distinguishing the two endosymbionts do not allow validating “C. macronucleorum” as a provisional taxon (Candidatus). Nevertheless, “C. macronucleorum” and C. caryophilus can be easily discriminated on the basis of a highly variable stretch of nucleotides that interrupts the 16S rRNA genes of both organisms.
Modification of host finding and oviposition behaviour of the citrus leafminer, Phyllocnistis citrella, by horticultural mineral oil
Authors: Liu Z. M. , Meats A. , Beattie G. A. C.
Published: October 2006

Horticultural mineral oil (HMO) deposits affect postlanding searching behaviour and contact evaluation of oviposition substrates by females of the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Both unsprayed and sprayed lemon trees were equally capable of arresting randomly moving female moths by eliciting kinetic responses. The presence of HMO deposits did not affect the approach of female moths to flushes (shoots with immature leaves suitable as oviposition sites), and female moths were equally likely to land on sprayed and unsprayed immature flushes provided mature leaves were not sprayed. The presence of HMO on both the mature leaves and the flushes caused shorter residence and search times within trees and also resulted in fewer immature leaves visited. The HMO‐sprayed flushes were also more likely to be rejected for oviposition after contact. Nevertheless, eggs were sometimes deposited on sprayed flushes between residues of the oil droplets.
Colocalization of lipedematous scalp and nevus lipomatosus superficialis: a case report
Authors: Mansur A. Tülin , Yasar Sirin , Aydingöz Ikbal Esen , Göktay Fatih , Özdemir Nilgün , Sungurlu Faik
Published: October 2006

Lipedematous scalp (LS) is a rare condition of unknown etiology characterized by a thick, boggy scalp that occurs mostly in adult black females. The main pathologic finding consists of increased thickness of scalp resulting from thickening of the subcutaneous fat layer.

Nevus lipomatosus superficialis (NLS) is an uncommon hamartomatous skin tumor characterized by soft, yellowish papules, or cerebriform plaques, usually localized on the buttock or thigh.

Here, we report a 46‐year‐old woman who has NLS localized on the occipital area, accompanied by LS just beneath and peripheral area of this plaque. The diagnoses of NLS and LS were established by histopathological examination. In addition, the increase in subcutaneous fat layer was demonstrated using magnetic resonance imaging.

The presented patient is the first case showing colocalization of NLS and LS.
H63D homozygotes with hyperferritinaemia: is this genotype, the primary cause of iron overload?
Authors: De Diego Carles , Opazo Sonsoles , Murga Maria J. , Martínez‐Castro Pedro
Published: October 2006

Objectives: Hereditary haemochromatosis is a disease that affects iron metabolism and leads to iron overload. Homozygosity for the H63D mutation is associated with increased transferrin saturation (TS) and ferritin levels. Our objective was to find out if the homozygosity of H63D mutation was the primary cause of iron overload. Patients and methods: We studied 45 H63D homozygotes (31 males and 14 females) with biochemical iron overload and/or clinical features of haemochromatosis. The simultaneous detection of 18 known HFE, TFR2 and FPN1 mutations and sequencing of the HAMP gene were performed to rule out the possible existence of genetic modifier factors related with iron overload. Results: Values of biochemical iron overload, measured as percentage TS and serum ferritin concentration (SF), in our H63D homozygotes were significantly higher in patients than in controls: TS 55 ± 15% vs. 35 ± 15% and SF 764 (645–883) μg/L vs. 115 (108–123) μg/L for patients and controls, respectively. These H63D homozygotes presented extreme hyperferritinaemia and no additional mutations in HFE, TFR2, FPN1 and HAMP genes were detected. Conclusions: The lack of additional mutations in our H63D homozygotes suggests that this genotype could be the primary cause of iron overload in these patients. Despite our results, we cannot entirely discount the possibility that one or more genetic modifier factor exists, simply because we were unable to find it, although there was a precedent in the HFE gene. Genetic modifier factors have been described for C282Y mutations in the HFE gene, but at the present time they have never been reported in H63D homozygotes.
Estimation of Wind-Sea and Swell Components in a Bimodal Sea State
Authors: Ewans K. C. , Bitner-Gregersen E. M. , Soares C. Guedes
Published: October 2006

Methods for separating the spectral components and describing bimodal wave spectra are evaluated with reference to wave spectra from directional wave measurements made at the Maui location off the west coast of New Zealand. Two methods involve partitioning bimodal wave spectra into wind-sea and swell components and then fitting a spectral function to each component, while the third assigns an average spectral shape based on the integrated spectral parameters. The partitioning methods involve separating the wave spectrum into two frequency bands: a low-frequency peak, the swell component, and a high-frequency peak, the wind-sea. One partitioning method uses only the frequency spectrum while the other analyzes the complete frequency-direction spectrum. Comparison of the spectral descriptions and derived parameters against the measured counterparts provides insight into the accuracy of the different approaches to describing actual bimodal sea states.
A Two-Dimensional Linear Assumed Strain Triangular Element for Finite Deformation Analysis
Authors: Flores Fernando G.
Published: October 2006

An assumed strain approach for a linear triangular element able to handle finite deformation problems is presented in this paper. The element is based on a total Lagrangian formulation and its geometry is defined by three nodes with only translational degrees of freedom. The strains are computed from the metric tensor, which is interpolated linearly from the values obtained at the mid-side points of the element. The evaluation of the gradient at each side of the triangle is made resorting to the geometry of the adjacent elements, leading to a four element patch. The approach is then nonconforming, nevertheless the element passes the patch test. To deal with plasticity at finite deformations a logarithmic stress-strain pair is used where an additive decomposition of elastic and plastic strains is adopted. A hyper-elastic model for the elastic linear stress-strain relation and an isotropic quadratic yield function (Mises) for the plastic part are considered. The element has been implemented in two finite element codes: an implicit static/dynamic program for moderately non-linear problems and an explicit dynamic code for problems with strong nonlinearities. Several examples are shown to assess the behavior of the present element in linear plane stress states and non-linear plane strain states as well as in axi-symmetric problems.
Investigation of the Dynamics of Microend Milling—Part I: Model Development
Authors: Jun Martin B. G. , Liu Xinyu , DeVor Richard E. , Kapoor Shiv G.
Published: October 2006

In microend milling, due to the comparable size of the edge radius to chip thickness, chip formation mechanisms are different. Also, the design of microend mills with features of a large shank, taper, and reduced diameter at the cutting edges introduces additional dynamics and faults or errors at the cutting edges. A dynamic microend milling cutting force and vibration model has been developed to investigate the microend milling dynamics caused by the unique mechanisms of chip formation as well as the unique microend mill design and its associated fault system. The chip thickness model has been developed considering the elastic-plastic nature in the ploughing process. A slip-line field modeling approach is taken for a cutting force model development that accounts for variations in the effective rake angle and dead metal cap. The process fault parameters associated with microend mills have been defined and their effects on chip load have been derived. Finally, a dynamic model has been developed considering the effects of both the unique microend mill design and fault system and factors that become significant at high spindle speeds including rotary inertia and gyroscopic moments.
Fuzzy Control of Spindle Torque in High-Speed Milling Processes
Authors: Haber-Guerra Rodolfo , Liang Steven Y. , Alique José R. , Haber-Haber Rodolfo
Published: October 2006

This paper presents the design and implementation of a two-input/two-output fuzzy logic-based torque control system embedded in an open architecture computer numerical control (CNC) for optimizing the material removal rate in high-speed milling processes. The control system adjusts the feed rate and spindle speed simultaneously as needed to regulate the cutting torque using the CNC’s own resources. The control system consists of a two-input (i.e., torque error and change of error), two-output (i.e., feed rate and spindle speed increment) fuzzy controller, which is embedded within the kernel of a standard open control. Two approaches are tested, and their performance is assessed using several performance measurements. These approaches are a two-input/two-output fuzzy controller and a single-output (i.e., feed rate modification only) fuzzy controller. The results demonstrate that the proposed control strategy provides better accuracy and machining cycle time than other strategies, thus increasing the metal removal rate.
Three-Dimensional Optical Measurements of Porous Foams
Authors: Shih Albert J. , Huang Zhenhua
Published: October 2006

The optical, noncontact stereovision system and data analysis procedure are developed for the measurement of porous foams. The stereovision measurement system has demonstrated the capability to capture both the micro-scale features and the macro-scale shape of both the open-cell and closed-cell porous foams. A computational procedure, denoted as the grid method, is developed to identify representative planes on the porous foam surface using the stereovision measured data points. The relative positions between planes can be used to calculate the angles and distances between porous foam surfaces. A SiC open-cell and an aluminum closed-cell foams are used as examples to validate the grid method and demonstrate its computational efficiency. This research enables the form measurements and geometrical dimensioning and tolerancing of porous foams for quality control and assembly and contact analysis.
Constitutive Modeling
and Discontinuous Bifurcation Assessment in Unsaturated
Soils
Authors: Schiava Ricardo , Etse Guillermo
Published: October 2006

In this work an elastoplastic constitutive theory for unsaturated soils is presented. The proposed material model is formulated in the general framework of the theory of porous media and of the flow theory of plasticity. The model is based on an extension of the well-known MRS Lade model whereby the suction and the effective stress tensor are introduced as additional independent and dependent stress components, respectively. Consequently the cap and cone yield conditions of the MRS Lade model both in hardening and softening as well as the internal evolution laws in these regimes are redefined to include the dependency on the suction. The paper illustrates the predictive capability of the extended MRS Lade model for partially saturated soils. Finally, the condition for discontinuous bifurcation in elastoplastic partially saturated porous media as well as the localized failure predictions of the proposed material formulation for different suctions and stress states are also analyzed and discussed.
Numerical Simulations of an Active-Stressing Technique for Delaying Fracture During Cutting of Alumina
Authors: Akarapu R. , Segall A. E.
Published: October 2006

During a variety of high-speed cutting operations that can include both laser and traditional saw methods, full workpiece support is not always practical or even possible. As a result, costly premature fractures and associated damage such as chips, burrs, and cracks (ranging from the micro- all the way to the macroscale) can result. In most instances, the resulting stresses are primarily mechanical in nature and arise from the bending and/or twisting moments from the still attached scrap. Under these conditions, mixed-mode fracture is all but inevitable since the supporting section is continuously diminishing as the cut progresses. Given the predominantly mechanical, and therefore predictable, nature of the resulting stresses, it is conceivable that intentionally induced, compressive stresses due to an off-focus laser might be used to control (or at least, delay) such fractures. In this paper, the possibility of using a tailored laser-heating scenario ahead of a progressing cut to “actively” induce compressive thermal stresses to control fracture of a cantilevered plate was numerically investigated. A simulation of this active-stressing approach was achieved by using a customized finite-element formulation that was previously employed to model dual-beam laser machining. However, in this instance probabilistic fracture mechanics was used to quantify the influence of the induced compressive stresses on the time and nature of the fracture. The effect of important parameters such as CO2 beam diameter, incident power density, positioning of the laser with respect to cut, as well as timing were then studied with respect to the goal of reducing and/or delaying the likelihood of fracture.
The story of c
Authors: Mendelson Kenneth S.
Published: October 2006

The letter c is the standard symbol for the speed of light, but that was not always the case. I describe how c was first introduced into the theory of electromagnetism and the stages by which it came to be used to denote the speed of light.
Undergraduate student laboratory experience at the Synchrotron Radiation Center
Authors: Sahyun Steven C. , Polak Jeffrey M. , Moore Christopher J.
Published: October 2006

We describe the structure of an intermediate physics laboratory course, a significant component of which is dedicated to having students perform hands-on experiments and real-time data collection at the Synchrotron Radiation Center national laboratory operated by the University of Wisconsin-Madison. We comment on student feedback on how this experience affected their attitudes and expectations of physics.
Helicobacter pylori
FlhB Function: the FlhB C-Terminal Homologue HP1575 Acts as a “Spare Part” To Permit Flagellar Export When the HP0770 FlhB
CC
Domain Is Deleted
Authors: Wand Matthew E. , Sockett R. Elizabeth , Evans Katy J. , Doherty Neil , Sharp Paul M. , Hardie Kim R. , Winzer Klaus
Published: October 2006

In
Helicobacter pylori
26695, a gene annotated HP1575 encodes a putative protein of unknown function which shows significant similarity to part of the C-terminal domain of the flagellar export protein FlhB. In
Salmonella enterica
, this part (FlhB
CC
) is proteolytically cleaved from the full-length FlhB, a processing event that is required for flagellar protein export and, thus, motility. The role of FlhB (HP0770) and its C-terminal homologue HP1575 was studied in
H. pylori
using a range of nonpolar deletion mutants defective in HP1575, HP0770, and the CC domain of HP0770 (HP0770
CC
). Deletion of HP0770 abolished swimming motility, whereas mutants carrying a deletion of either HP1575 or HP0770
CC
retained their ability to swim. An
H. pylori
strain containing deletions in both HP1575 and HP0770
CC
was nonmotile and did not produce flagella, suggesting that at least one of the two proteins had to be present for flagellar assembly to occur. Indeed, motility was restored when HP1575 was reintroduced into this strain immediately downstream of, but not fused to, the truncated HP0770 gene. Thus, HP1575 can functionally replace HP0770
CC
in this background. Like FlhB in
S. enterica
, HP0770 appeared to be proteolytically processed at a conserved NPTH processing site. However, mutation of the proline contained within the NPTH site of HP0770 did not affect motility and flagellar assembly, although it clearly interfered with processing when the protein was heterologously produced in
Escherichia coli
.
Transcriptome Profiling Reveals the Importance of Plasmid pSymB for Osmoadaptation of
Sinorhizobium meliloti
Authors: Domínguez-Ferreras Ana , Pérez-Arnedo Rebeca , Becker Anke , Olivares José , Soto María J. , Sanjuán Juan
Published: October 2006

In this work, DNA microarrays were used to investigate genome-wide transcriptional responses of
Sinorhizobium meliloti
to a sudden increase in external osmolarity elicited by addition of either NaCl or sucrose to exponentially growing cultures. A time course of the response within the first 4 h after the osmotic shock was established. We found that there was a general redundancy in the differentially expressed genes after NaCl or sucrose addition. Both kinds of stress resulted in induction of a large number of genes having unknown functions and in repression of many genes coding for proteins with known functions. There was a strong replicon bias in the pattern of the osmotic stress response; whereas 64% of the upregulated genes had a plasmid localization, 85% of the downregulated genes were chromosomal. Among the pSymB osmoresponsive genes, 83% were upregulated, suggesting the importance of this plasmid for
S. meliloti
osmoadaptation. Indeed, we identified a 200-kb region in pSymB needed for adaptation to saline shock which has a high density of osmoregulated genes.
Helicobacter pylori
Genes Involved in Avoidance of Mutations Induced by 8-Oxoguanine
Authors: Mathieu Aurélie , O'Rourke Eyleen J. , Radicella J. Pablo
Published: October 2006

Chromosomal rearrangements and base substitutions contribute to the large intraspecies genetic diversity of
Helicobacter pylori
. Here we explored the base excision repair pathway for the highly mutagenic 8-oxo-7,8-dihydroguanine (8-oxoG), a ubiquitous form of oxidized guanine. In most organisms, 8-oxoG is removed by a specific DNA glycosylase (Fpg in bacteria or OGG1 in eukaryotes). In the case where replication of the lesion yields an A/8-oxoG base pair, a second DNA glycosylase (MutY) can excise the adenine and thus avoid the fixation of the mutation in the next round of replication. In a genetic screen for
H. pylori
genes complementing the hypermutator phenotype of an
Escherichia coli fpg mutY
strain, open reading frame HP0142, a putative MutY coding gene, was isolated. Besides its capacity to complement
E. coli mutY
strains, HP0142 expression resulted in a strong adenine DNA glycosylase activity in
E. coli mutY
extracts. Consistently, the purified protein also exhibited such an activity. Inactivation of HP0142 in
H. pylori
resulted in an increase in spontaneous mutation frequencies. An Mg-dependent AP (abasic site) endonuclease activity, potentially allowing the processing of the abasic site resulting from
H. pylori
MutY activity, was detected in
H. pylori
cell extracts. Disruption of HP1526, a putative
xth
homolog, confirmed that this gene is responsible for the AP endonuclease activity. The lack of evidence for an Fpg/OGG1 functional homolog is also discussed.
Temperature Dependence of MinD Oscillation in
Escherichia coli
: Running Hot and Fast
Authors: Touhami Ahmed , Jericho Manfred , Rutenberg Andrew D.
Published: October 2006

We observed that the oscillation period of MinD within rod-like and filamentous cells of
Escherichia coli
varied by a factor of 4 in the temperature range from 20°C to 40°C. The detailed dependence was Arrhenius, with a slope similar to the overall temperature-dependent growth curve of
E. coli
. The detailed pattern of oscillation, including the characteristic wavelength in filamentous cells, remained independent of temperature. A quantitative model of MinDE oscillation exhibited similar behavior, with an activated temperature dependence of the MinE-stimulated MinD-ATPase rate.
Posttranslational Modification of the 20S Proteasomal Proteins of the Archaeon
Haloferax volcanii
Authors: Humbard Matthew A. , Stevens Stanley M. , Maupin-Furlow Julie A.
Published: October 2006

20S proteasomes are large, multicatalytic proteases that play an important role in intracellular protein degradation. The barrel-like architecture of 20S proteasomes, formed by the stacking of four heptameric protein rings, is highly conserved from archaea to eukaryotes. The outer two rings are composed of α-type subunits, and the inner two rings are composed of β-type subunits. The halophilic archaeon
Haloferax volcanii
synthesizes two different α-type proteins, α1 and α2, and one β-type protein that assemble into at least two 20S proteasome subtypes. In this study, we demonstrate that all three of these 20S proteasomal proteins (α1, α2, and β) are modified either post- or cotranslationally. Using electrospray ionization quadrupole time-of-flight mass spectrometry, a phosphorylation site of the β subunit was identified at Ser129 of the deduced protein sequence. In addition, α1 and α2 contained N-terminal acetyl groups. These findings represent the first evidence of acetylation and phosphorylation of archaeal proteasomes and are one of the limited examples of post- and/or cotranslational modification of proteins in this unusual group of organisms.
Knockout and Overexpression of Pyrroloquinoline Quinone Biosynthetic Genes in
Gluconobacter oxydans
621H
Authors: Hölscher Tina , Görisch Helmut
Published: October 2006

In
Gluconobacter oxydans
, pyrroloquinoline quinone (PQQ) serves as the cofactor for various membrane-bound dehydrogenases that oxidize sugars and alcohols in the periplasm. Proteins for the biosynthesis of PQQ are encoded by the
pqqABCDE
gene cluster. Our reverse transcription-PCR and promoter analysis data indicated that the
pqqA
promoter represents the only promoter within the
pqqABCDE
cluster of
G. oxydans
621H. PQQ overproduction in
G. oxydans
was achieved by transformation with the plasmid-carried
pqqA
gene or the complete
pqqABCDE
cluster. A
G. oxydans
mutant unable to produce PQQ was obtained by site-directed disruption of the
pqqA
gene. In contrast to the wild-type strain, the
pqqA
mutant did not grow with
d
-mannitol,
d
-glucose, or glycerol as the sole energy source, showing that in
G. oxydans
621H, PQQ is essential for growth with these substrates. Growth of the
pqqA
mutant, however, was found with
d
-gluconate as the energy source. The growth behavior of the
pqqA
mutant correlated with the presence or absence of the respective PQQ-dependent membrane-bound dehydrogenase activities, demonstrating the vital role of these enzymes in
G. oxydans
metabolism. A different PQQ-deficient mutant was generated by Tn
5
transposon mutagenesis. This mutant showed a defect in a gene with high homology to the
Escherichia coli tldD
gene, which encodes a peptidase. Our results indicate that the
tldD
gene in
G. oxydans
621H is involved in PQQ biosynthesis, possibly with a similar function to that of the
pqqF
genes found in other PQQ-synthesizing bacteria.
INTEGRATION TESTING OF CONTEXT-SENSITIVE MIDDLEWARE-BASED APPLICATIONS: A METAMORPHIC APPROACH
Authors: CHAN W. K. , CHEN T. Y. , LU HENG , TSE T. H. , YAU STEPHEN S.
Published: October 2006

During the testing of context-sensitive middleware-based software, the middleware checks the current situation to invoke the appropriate functions of the applications. Since the middleware remains active and the situation may continue to evolve, however, the conclusion of some test cases may not easily be identified. Moreover, failures appearing in one situation may be superseded by subsequent correct outcomes and, therefore, be hidden.

We alleviate the above problems by making use of a special kind of situation, which we call checkpoints, such that the middleware will not activate the functions under test. We recommend testers to generate test cases that start at a checkpoint and end at another. Testers may identify relations that associate different execution sequences of a test case. They then check the results of each test case to detect any contravention of such relations. We illustrate our technique with an example that shows how hidden failures can be detected. We also report the experimentation carried out on an RFID-based location-sensing application on top of a context-sensitive middleware.
ACTION MACHINES: A FRAMEWORK FOR ENCODING AND COMPOSING PARTIAL BEHAVIORS
Authors: GRIESKAMP WOLFGANG , KICILLOF NICOLAS , TILLMANN NIKOLAI
Published: October 2006

We describe action machines, a framework for encoding and composing partial behavioral descriptions. Action machines encode behavior as a variation of labeled transition systems where the labels are observable activities of the described artifact and the states capture full data models. Labels may also have structure, and both labels and states may be partial with a symbolic representation of the unknown parts. Action machines may stem from software models or programs, and can be composed in a variety of ways to synthesize new behaviors. The composition operators described here include synchronized and interleaving parallel composition, sequential composition, and alternating simulation. We use action machines in analysis processes such as model checking and model-based testing. The current main application is in the area of model-based conformance testing, where our approach addresses practical problems users at Microsoft have in applying model-based testing technology.