bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiple trichoepitheliomas – a novel mutation in the CYLD gene
Authors: Amaro C , Freitas I , Lamarão P , Afonso A , Skrzypczak M , Heinritz W
Published: November 2009

Background  Trichoepitheliomas are benign neoplasms with follicular differentiation. They may present as a solitary lesion or as multiple lesions. Multiple trichoepitheliomas are inherited in an autosomal dominant pattern within families, with both variable penetrance and expressivity. Recent investigations support that mutations in CYLD, the gene affected in familial cylindromatosis as well as in Brooke–Spiegler syndrome, are also responsible for multiple trichoepitheliomas.

Objective  The authors report the case of a 9‐year‐old African girl with multiple facial trichoepitheliomas in whom a mutation in the CYLD gene was hypothesised.

Materials and methods  After genomic DNA extraction from the peripheral blood, a molecular analysis of the CYLD gene was performed by PCR, DHPLC and automated sequencing.

Results  A novel heterozygous mutation in exon 18 of the CYLD gene (c.2449delT) was identified, with a deletion of one nucleotide resulting in a premature translational termination codon at amino acid position 831 on the affected allele (p.Cys817Valfs X15).

Conclusions  The predominating tumours define the classification of these three entities. Nevertheless, studies suggest that they can simply represent phenotypic variations of the same disease spectrum, sharing common genetic mutations.
Sutural growth restriction and modern human facial evolution: an experimental study in a pig model
Authors: Holton Nathan E. , Franciscus Robert G. , Nieves Mary Ann , Marshall Steven D. , Reimer Steven B. , Southard Thomas E. , Keller John C. , Maddux Scott D.
Published: November 2009

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper. The present analysis was designed to assess anteroposterior facial reduction in a pig model and to examine the potential role that this dynamic has played in the evolution of modern human facial form. Ten female sibship cohorts, each consisting of three individuals, were allocated to one of three groups. In the experimental group (n = 10), microplates were affixed bilaterally across the zygomaticomaxillary and frontonasomaxillary sutures at 2 months of age. The sham group (n = 10) received only screw implantation and the controls (n = 10) underwent no surgery. Following 4 months of post‐surgical growth, we assessed variation in facial form using linear measurements and principal components analysis of Procrustes scaled landmarks. There were no differences between the control and sham groups; however, the experimental group exhibited a highly significant reduction in facial projection and overall size. These changes were associated with significant differences in the infraorbital region of the experimental group including the presence of an infraorbital depression and an inferiorly and coronally oriented infraorbital plane in contrast to a flat, superiorly and sagittally infraorbital plane in the control and sham groups. These altered configurations are markedly similar to important additional facial features that differentiate modern humans from archaic Homo, and suggest that facial length restriction via rigid plate fixation is a potentially useful model to assess the developmental factors that underlie changing patterns in craniofacial form associated with the emergence of modern humans.
Individual and Issue‐Specific Differences in Parental Knowledge and Adolescent Disclosure in Chile, the Philippines, and the United States
Authors: Darling Nancy , Cumsille Patricio , Peña‐Alampay Liane , Coatsworth Douglas
Published: November 2009

Perceived parental knowledge and adolescents' disclosure to parents were predicted from parental warmth and monitoring and adolescents' disclosure, agreement, and beliefs about obligation to obey and parental legitimacy (N=698 Chilean, Filipino, and U.S. 13–20‐year‐olds). The correlates of knowledge are similar in all three countries, but the relative strength of the correlations differs. Global agreement was associated with greater knowledge. Parents knew most about issues governed by rules and those where adolescents agreed, felt obliged to obey, and disclosed. Monitoring predicted knowledge only in Chile and the Philippines. Warmth was a stronger predictor of knowledge in the United States. Key predictors of disclosure include agreement in Chile, agreement and rules in the Philippines, and warmth and rules in the United States.
Acculturation and Enculturation Trajectories Among Mexican‐American Adolescent Offenders
Authors: Knight George P. , Vargas‐Chanes Delfino , Losoya Sandra H. , Cota‐Robles Sonia , Chassin Laurie , Lee Joanna M.
Published: November 2009

This study examines changes over time in ethnic affirmation/belonging and ethnic identity achievement, Spanish language use, English language use, Mexican/Mexican‐American affiliation/identification and Anglo affiliation/identification in a sample of Mexican‐American adolescents participating in a longitudinal study of juvenile offenders. The Multigroup Ethnic Identity Measure and the Acculturation Rating Scale for Mexican Americans‐II were completed by the Mexican‐American adolescents 7 times over a 3‐year period. The findings from longitudinal growth modeling analyses and growth mixture modeling analyses indicate that there is heterogeneity in the initial scores and changes over time on these variables that are related to markers for the cultural qualities of the home environment (i.e., generational status and mother's most frequent language use). In contrast to expectations, marginalized or assimilated acculturation trajectories/types were not overrepresented in this sample of adolescent offenders. Implications for our understanding of the nature of acculturation and enculturation processes and the way these processes are studied are discussed.
BLOOD DONORS AND BLOOD COLLECTION: Status of blood banking and the blood supply in Afghanistan
Authors: Ayyoubi M. Tayyeb , Konstenius Terri , McCullough Jeffrey C. , Eastlund Ted , Clay Mary , Bowman Robert , Rahmani Ahmad Masoud , Riley William , McCullough Jeffrey
Published: November 2009

BACKGROUND: As a result of more than 20 years of war in Afghanistan, its blood supply system has been damaged. We carried out an assessment of that blood supply system to determine the type and extent of assistance needed to increase blood availability and safety.

STUDY DESIGN AND METHODS: An assessment tool was developed, daily activities in Afghanistan were observed, and key personnel were interviewed.

RESULTS: Because there was no donor recruitment organization, most blood was obtained by the family replacement system. There was an inadequate supply of stored blood, which led to use of blood before screening test results for transfusion‐transmitted disease were complete. Whole blood was provided but blood components were not produced. Blood was tested intermittently for human immunodeficiency virus Types 1 and 2, hepatitis B surface antigen, hepatitis C virus, and syphilis using agglutination‐based screening methods.

CONCLUSIONS: A dedicated staff is in place but to strengthen the blood supply system in Afghanistan, it will be important to address infrastructure and facilities, organization, standard operating methods, supplies and equipment, training, quality assurance, and transfusion medicine education.
Demographic variations in blood donor deferrals in a major metropolitan area
Authors: Shaz B.H. , James A.B. , Hillyer K.L. , Schreiber G.B. , Hillyer C.D.
Published: November 2009

BACKGROUND: Presenting blood donors are screened to ensure both their safety and that of the recipients of blood products. Donors with identified risks are deferred from donating blood either temporarily or permanently. Minorities are underrepresented as donors in the United States and this may in part be a result of increased donor deferral rates in minorities compared to white individuals.

STUDY DESIGN AND METHODS: Data consisted of deferred and successful blood donor presentations to the American Red Cross Southern Region in the metropolitan Atlanta area in 2004 to 2008. Bivariate and multivariate analyses were conducted by race/ethnicity, age group, and sex.

RESULTS: A total of 586,159 voluntary donor presentations occurred in 2004 to 2008, of which 79,214 (15.6%) resulted in deferral. In the age 16 to 69 years subset (98.3% of the presentations), deferred presentations were mostly women (78.2%). The most common reason for donor deferral was low hemoglobin (62.6%). The donor deferral rate varied by race/ethnicity, age, and sex: whites (11.1%), Hispanics (14.1%), and African Americans (17.9%); 16‐ to 19‐year‐olds (17.0%) and 50‐ to 59‐year‐olds (11.7%); and females (20.0%) and males (6.2%). Compared to whites and Hispanics, African American females had the highest deferral rate in each age group.

CONCLUSIONS: Minorities are disproportionately impacted by blood donor deferrals. Methods to decrease blood donor deferral rates among African Americans are needed.
Evaluation of low platelet counts by optical, impedance, and CD61‐immunoplatelet methods: estimation of possible inappropriate platelet transfusion
Authors: Cid Joan , Nascimento Janilson Do , Vicent Ana , Aguinaco Reyes , Escoda Lourdes , Ugarriza Aranzazu , Llorente Andreu
Published: November 2009

BACKGROUND: The Cell‐Dyn Sapphire (Abbott Diagnostics) detects platelets (PLTs) with a CD61 monoclonal antibody directed against glycoprotein IIIa as well as impedance (IMP) and optical (OPT) technology. We decided to evaluate low PLT counts produced by IMP and OPT methods and to compare them with the CD61 method. We also examined the possibility of inappropriate PLT transfusion resulting from an inaccurate PLT count.

STUDY DESIGN AND METHODS: We analyzed consecutive blood samples with OPT PLT counts of less than 50 × 109/L. We performed the PLT count with the OPT, IMP, and CD61 methods and we compared the number of prophylactic PLT transfusion indications according to the PLT counts determined by the OPT and IMP methods with the number of prophylactic PLT transfusion indications according to our reference CD61 method.

RESULTS: We collected 135 samples. In the bias analysis, the OPT method and the IMP method showed higher PLT counts when compared with the CD61 method (mean of difference 1.69 × 109 and 19.1 × 109/L, respectively). We saw overtransfusion in 1.5% of cases and undertransfusion in 15.2% of cases (p = 0.01; McNemar's test) when we selected a threshold of 10 × 109/L with the OPT method. We saw undertransfusion in 22.2% of cases (p = 0.03; McNemar's test) when we selected a threshold of 5 × 109/L with the OPT method.

CONCLUSIONS: Low PLT counts determined by the OPT and IMP methods showed some disagreement when compared with the CD61 method. This disagreement caused both PLT undertransfusion and overtransfusion.
Guardians of the Bourgeois City: Citizenship, Public Space, and Middle–Class Activism in Mumbai
Authors: Anjaria Jonathan Shapiro
Published: November 2009

This article examines the new phenomenon of “citizens’ groups” in contemporary Mumbai, India, whose activities are directed at making the city's public spaces more orderly. Recent scholarship on Mumbai's efforts to become a “global” city has pointed to the removal of poor populations as an instance of neoliberal governmentality as espoused by the Indian state following the “liberalization” of the economy in the early 1990s. However, in this case, it is these civil society organizations, not the state—whose functionaries in fact benefit from a certain element of unruliness on the streets—who are the agents of increased control over populations and of the rationalization of urban space. This article, based on fieldwork–based research, argues that the way in which citizens’ groups exclude poor populations from the city is more complex than a straightforward deployment of neoliberalism, and is imbricated with transnational political economic arrangements in uneven and often inconsistent ways. in particular, this article explores how civic activists in these organizations envision their role in the city, and how their activism attempts to reconfigure the nature of citizenship. for instance, civic activists consider themselves to be the stewards of the city's streets and sidewalks, and wage their battles against what they consider unruly hawkers, a corrupt state, and a complacent middle–class public. Moreover, civic activists render street hawkers’ political claims illegitimate by speaking on behalf of the abstract “citizen”of Mumbai, thus implying that hawkers’ unions speak only on behalf of the vested interests of a single population. in this way, they mobilize a normative notion of civil society in order to exclude the vast segment of city residents who either sell or buy goods on the street. in doing so, the civic activists transform the discourse and practice of politics in the city, so that, ironically, while on one hand using the rhetoric of citizen participation, they in fact undermine the radically heterogeneous forms of democratic political participation the city offers.
Localizing the Production of Global Cities: A Comparison of New Town Developments around Shanghai and Kolkata
Authors: Chen Xiangming , Wang Lan , Kundu Ratoola
Published: November 2009

This article investigates the role played by the state in the production and management of urban space vis–à–vis global agents of change. the proliferation of new towns and special economic zones as urban restructuring strategies in rapidly developing countries like China and India are receiving much attention from the scholarly community, documenting and interrogating urban transitions from centralized planning to more participatory and often privatized modes of decentralized planning. This article seeks to tease out the kinds of relationships between the state and other urban development actors it entails, ranging from conflict to collaboration, from protest to partnerships, and from contestation to collaboration. in the Shanghai Metropolitan context, we focus on Anting New Town and Songjiang New City as two cases for understanding the relative power of the municipal government, global capital, professional planning, and the limited influence of local residents in the process and outcome of large–scale suburban development. as a comparison, we focus on the West Bengal State government's role in the development of two new townships (Rajarhat New Town and the Kolkata West International City) on the fringes of the existing core city of Kolkata (Calcutta), India. Drawing on a number of secondary sources such as development plans, newspaper articles, field–based observations, and informal discussions and interviews with official town planners, architects, and private planners, our goal is to compare and contrast the two strategies foregrounding the practices and the relationship of the state to the forces of privatization and globalization, to local grassroots actors and the precarious as well as multifarious ways in which it seeks to constantly negotiate with the dynamics of development. It seeks to answer: what kind of challenges does the state face in reorganizing the urban? Who are the other actors involved in the negotiations and exclusions, contestations, and collaborations? What are the new sociospatial, economic, and political boundaries and contents of the spaces produced?
Effects of plyometric training on passive stiffness of gastrocnemii and the musculo‐articular complex of the ankle joint
Authors: Fouré A. , Nordez A. , Guette M. , Cornu C.
Published: November 2009

This study aimed to determine simultaneously the effects of plyometric training on the passive stiffness of the ankle joint musculo‐articular complex, the gastrocnemii muscle–tendon complex (MTC) and the Achilles tendon in order to assess possible local adaptations of elastic properties. Seventeen subjects were divided into a trained (TG) group and a control (CG) group. They were tested before and after 8 weeks of a plyometric training period. The ankle joint range of motion (RoM), the global musculo‐articular passive stiffness of the ankle joint, the maximal passive stiffness of gastrocnemii and the stiffness of the Achilles tendon during isometric plantar flexion were determined. A significant increase in the jump performances of TG relative to CG was found (squat jumps: +17.6%, P=0.008; reactive jumps: +19.8%, P=0.001). No significant effect of plyometric training was observed in the ankle joint RoM, musculo‐articular passive stiffness of the ankle joint or Achilles tendon stiffness (P>0.05). In contrast, the maximal passive stiffness of gastrocnemii of TG increased after plyometric training relative to CG (+33.3%, P=0.001). Thus, a specific adaptation of the gastrocnemii MTC occurred after plyometric training, without affecting the global passive musculo‐articular stiffness of the ankle joint.
Potentiation of Acid Sham Feeding Response in Pavlov Pouch Dogs by Histamine and by Mesenteric‐Caval Vein Anastomosis
Authors: Olbe Lars
Published: November 2009

The acid sham feeding responses in Pavlov pouch dogs were almost abolished by resection of the main sources of endogenous gastrin. A marked increase of the sham feeding responses appeared in these dogs on concomitant i. v. infusion of subthreshold amounts of histamine (5—43 times in 5 dogs) or after a mesenteric‐caval vein anastomosis (7—20 times in 5 dogs). Thus the quality to potentiate the direct vagal action on the gastric HC1‐glands is not a characteristic of gastrin but a property that gastrin shares with other humoral secretogogues. The nature of the intestinal agent causing the hypersecretory sham feeding response after mesenteric‐caval anastomosis is discussed in view of 1) the comparatively larger augmentation of the response by subthreshold amounts of histamine than by the vein anastomosis, and 2) the increased fasting acid secretion after the mesenteric‐caval anastomosis.
Reproducibility and desensitization of the power frequency magnetic field effect on movement of the common cutworm Spodoptera litura
Authors: RYU Jeong‐Min , KIM Nam‐Jung , WON Ran , LEE Sang‐Dae , CHAE Kwon‐Seok
Published: November 2009

All creatures on Earth, including human beings, can be influenced by the power frequency electromagnetic field (EMF), even though the consequence and degree of the effect may vary due to regional context, species, etc. Most of the outstanding scientific achievements about the EMF effect on life have come from behavioral studies. In such studies, in contrast to the geomagnetic field or static magnetic field (MF), the oscillating MF has attracted far less attention so far. Following a previous report, to attain deep basic knowledge about the effect of an extremely low frequency (ELF) MF on animal behavior, we characterized the 60‐Hz MF‐responsive movement activity of common cutworm larvae using sophisticated experimental schemes. The MF‐exposed third instar larvae showed significantly reduced locomotive activity compared to the matching sham‐exposed larvae. Moreover, repeated MF exposure to the same larvae up to three times also showed similar behavioral responsiveness even though the extent of movement decrease was attenuated by the repetition time. These results suggest that sinusoidal power frequency MF could disrupt the normal locomotory activity of insect larvae, and the insects may show adaptive desensitization to the same MF.
Characterization of optimal growth conditions and carotenoid production of strain Rhodotorula mucilaginosa HP isolated from larvae of Pieris rapae
Authors: OH Jukyoung , JEONG Heonchun , OH Sejong
Published: November 2009

Yeasts have been studied because of their production of a pigment known as carotenoid with potential application in food and feed supplements. A carotenoid‐producing yeast was isolated from the larvae of Pieris rapae, named HP. The strain HP was identified as Rhodotorula mucilaginosa classified by its carbohydrate fermentation pattern and physiological tests. Rhodotorula mucilaginosa HP produces several exogenous enzymes: alkaline phosphatase, esterase, leucine arylamidase, valine arylamidase, acid phosphatase and β‐glucosidase. Using response surface methodology, selected medium components (yeast extract, malt extract, peptone, glucose) were tested to find the optimum conditions for carotenoid production and the growth of R. mucilaginosa HP. Central composite design was used to control the concentrations of medium components. Peptone and glucose had the largest effects on carotenoid production and cell growth of R. mucilaginosa HP, respectively. The estimated optimal growth conditions of R. mucilaginosa HP were: yeast extract 3.23%, malt extract 2.84%, peptone 6.99% and glucose 12.86%. The estimated optimal conditions for carotenoid production were: yeast extract 2.17%, malt extract 2.11%, peptone 5.79% and glucose 12.46%. These results will assist in the formulation of an appropriate culture medium for optimal carotenoid production of R. mucilaginosa HP for commercial use.
Insect herbivores associated with the introduced weed Bidens frondosa L. (Asteraceae) in Korea, and their potential role as augmentative biological control agents
Authors: HAN Yong‐Gu , CHO Youngho , KIM Youngjin , LIM Heonmyoung , KWON Ohseok , NAM Sang‐Ho
Published: November 2009

The annual herb Bidens frondosa L., native to North America, is an invasive weed. Currently no information is available on the insect herbivores associated with this weed in Korea. A survey was carried out at two‐weekly intervals from May to October 2008 at two sites, and the incidence and abundance of various insect herbivores studied. A total nine species of insects was recorded and among them the defoliating caterpillar Hadjina chinensis (Wallengren) (Lepidoptera) was the only species known to have host plants restricted to genus Bidens. Further host specificity studies are required to evaluate the potential of this insect as a candidate for augmentative biological control agent for B. frondosa in Korea. All other insect species are either polyphagous or known crop pests.
The Rayleigh Bearing
Authors: Poritsky Hillel
Published: November 2009

Common bearing theory cannot be applied to a Rayleigh bearing which we place at 0<y<h1forx<0,0<y0,h1>h2,(1) near x = 0. This paper is concerned with a more exact theory, providing (partial) differential equations whose solution can handle even the region near x = 0. In section 1, after the ordinary, approximate solution is reviewed, more exact equations are obtained for the flow, under the assumptions that the flow is nonturbulent, that the fluid is incompressible, and that its viscosity μ is constant. It is shown that the streamline function ψ is biharmonic, that it is a solution of the repeated Laplace equation ∇4ψ=∇2(∇2ψ)=0,(2) and proper boundary conditions are obtained for it. In section 2 it is recalled that equation (2) also occurs in certain plate problems, such as the normal deflection of a constant thickness plate given by equations (1), free from distributed normal load, and subject to proper deflections and slopes at its boundary. Again, equation (1) is also satisfied by Airy function H of the plate (1) subjected to normal and shearing tractions over its boundary. Based on the above, analogies are outlined between the fluid flow and the two plate problems, with ψ corresponding to ω and to H. These analogies can be used to obtain experimental solutions of the bearing flow problem. Section 3 is devoted to graphical and numerical solutions. The numerical methods are based on covering the area (1) with a square mesh, and approximating to the differential operators by finite difference quotients of values at the mesh points, yielding to a set of linear equations. These are solved either on a computer, or by assuming a solution and improving it successively. The graphical method involves conformal mapping of (1) onto a plane with a simpler boundary, such as an infinite strip. This can be carried out analytically, or graphically by means of two sets of orthogonal curves cutting (1) into small squates. Section 4 utilizes separate expansions of ψ in product biharmonics to each side of x = 0, and joining them up so that the integrated errors over x = 0 are minimized. Finally in Section 5 the biharmonic ψ is expressed in the form ψ=F+yG(3) where F and G are harmonic, and from the boundary conditions on ψ are obtained boundary values of F, G and/or their conjugate harmonics. The methods used involve Green’s functions and therefore are carried out best in the plane of the infinite strip.
Nonlinear Pad Functions for Static Analysis of Tilting Pad Bearings
Authors: Andritsos F. E. , Dimarogonas A. D.
Published: November 2009

An experimental procedure was developed for the determination of pad bearing performance by means of nonlinear stiffness pad functions. These functions describe the pad reaction for each location of the journal. The performance of the complete bearing is then computed from the assembly of the individual pad functions. This yields a complete static nonlinear description of the bearing forces. The same method, that is by using nonlinear damping pad functions, can as well be used for investigating the dynamic behavior of tilting pad bearings. This procedure can be used in two ways: (a) To tabulate the functions for an adequate constellation of the design parameters of the pads and from them compute the performance parameters of the bearing such as load carrying capacity and linear coefficients, (b) To incorporate these functions into a nonlinear numerical analysis of the dynamic response of the rotor-bearing system. Comparison of the static state results with previous investigations on complete bearings shows a good agreement while existing numerical solutions give unacceptable results for wide areas of bearings operation.
An Experimental Investigation Into the Rubber-Stabilization of an Externally-Pressurized Air-Lubricated Thrust Bearing
Authors: Boffey D. A. , Desai D. M.
Published: November 2009

Stability maps are presented for a circular thrust bearing which has a central feed hole and pocket and is flexibly supported on various rubber O-rings. Results obtained show that a substantial improvement in stability can be achieved compared with the normal fixed-pad arrangement. An earlier stability theory has been programmed with measured O-ring support data but qualitative agreement with experiment is attained only after modification of theory.
A Mixed Friction Hydrostatic Face Seal Model With Phase Change
Authors: Lebeck A. O.
Published: November 2009

A mixed friction hydrostatic mechanical face seal model is presented. Load support and friction due to mechanical contact and the effect of a phase change are considered. The results show that a phase change within the seal interface leads to a greater fraction of the load being supported by fluid film pressure than for an all liquid or all gas phase seal. As seal operating temperature approaches the boiling point of the sealed fluid, very high leakage is predicted. An explanation for puffing is offered. The effect of various design parameters on two phase seal operation is examined. On a theoretical basis, operation at a higher temperature reduces seal wear rate and friction. The model can be used by seal designers to predict instability and performance for a two phase seal.
An Attempt to Provide a Unified Treatment of Tribology Through Load Carrying Capacity, Transport, and Continuum Mechanics
Authors: Godet M. , Play D. , Berthe D.
Published: November 2009

This paper attempts to give a unified treatment of experiments obtained with solid, liquid and boundary lubricants, different plastics, high temperature steels and elastomers. The argument is centered around third body role, load-carrying capacity, transport and continuum mechanics. This study suggests that an extension to general tribology of the continuum approach used in full film lubrication could be profitable.
Inverse Hydrodynamic Methods Applied to Mr. Beauchamp Tower’s Experiments of 1885
Authors: Ettles C. M. McC. , Akkok M. , Cameron A.
Published: November 2009

The experiments of Mr. Beauchamp Tower and their subsequent interpretation by Professor Osborne Reynolds form the basis of all hydrodynamic lubrication theory. In the experiments described in his second report, Tower made nine pressure tappings in a 157 deg partial arc bearing. Reynolds assumed that the film shape corresponded to a circular bearing and analyzed the results on this assumption. Inverse hydrodynamic theory allows the calculation of the actual film shape from this measured pressure distribution. It is found that the film was a slightly convergent wedge which does not correspond to a fitted bearing as assumed by Tower and certainly not to the clearance bearing assumed by Reynolds. Existing methods of inverse hydrodynamic analysis require the second differential of the pressure profile (or its equivalent in the two-dimensional case) to become zero at some point in the film. The film thickness can be found directly at this point and then elsewhere by the solution of a cubic equation. Two separate and more general methods are developed in this paper in which this requirement for the second differential is unnecessary.
Lubricant Limiting Shear Stress Effect on EHD Film Thickness
Authors: Gecim B. , Winer W. O.
Published: November 2009

A Grubin-like EHD inlet analysis utilizing a non-linear viscous fluid model with a limiting shear stress is reported. The shear rheological equation requires only a low shear stress viscosity and the limiting shear stress both functions of pressure. Values employed for these properties are taken from measurements on typical lubricants. Reductions of EHD film thickness are found to be up to 40 percent compared with the standard Grubin prediction for typical operating conditions. Slide-roll ratio, limiting shear stress dependence on pressure, and atmospheric pressure value of limiting shear stress are new variables required to determine film thickness with the first two being more important than the last. The EHD film thickness is reduced by increasing slide-roll ratio and/or decreasing the pressure dependence of the limiting shear stress.
Third Body Formation and the Wear of PTFE Fibre-Based Dry Bearings
Authors: Lancaster J. K. , Play D. , Godet M. , Verrall A. P. , Waghorne R.
Published: November 2009

Dry bearing tests have been made with a PTFE fibre/glass fibre/phenolic resin composite against stainless steel to examine the influence of time of sliding, counterface roughness and load. The worn surfaces were examined by optical and scanning electron microscopy, energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy (ESCA). It is shown that the coefficient of friction and the rate of wear are strongly influenced by the formation of third bodies on both sliding surfaces. The structure and composition of these third bodies depend on the time of sliding and the load, but are independent of counterface roughness. Wear of the PTFE composite appears to occur on several scales, and considerable degradation of PTFE is evident within the third body (transfer film) on the counterface. The significance of these observations to the measured friction and wear rates is discussed.
Relation Between Wear of Cr.Ni Steels and Debris Transport at High Temperature (950°C)
Authors: Play D. , Godet M.
Published: November 2009

Visualization of the friction process of a Cr.Ni Steel pin running on a disk of similar material under nitrogen has shown that a built-up edge (b.u.e.) is gradually formed and eliminated at contact. The construction of the b.u.e. is described. Metallurgical sections of b.u.e. formed under different conditions are analysed and confirm mechanisms suggested by visualization. Both visualization and b.u.e. examinaton point to the importance of flow transport in friction processes.
Scuffing Resistance of Advanced Gear Material/Lubricant Combinations
Authors: Popgoshev D. , Valori R.
Published: November 2009

Two advanced carburizing grade gear steels were evaluated and compared against an AMS 6260 baseline material. Each material was evaluated on three lubricants (an unformulated ester basestock, a qualified MIL-L-23699B lubricant, and an advanced MIL-L-23699 type lubricant) to determine their gear scuffing/scoring capacities. The results show that (a) a 3Ni-4.5Mo alloy is superior to a 3Ni-2Cu alloy and to the AMS 6260 alloy with the lubricants evaluated, (b) the 3Ni-2Cu alloy is superior to the AMS 6260 with the fully formulated lubricants, and (c) the advanced MIL-L-23699 type lubricant showed significant load carrying capacity improvements for all three gear steels.
Effects of Asperities in Elastohydrodynamic Lubrication
Authors: Kaneta M. , Cameron A.
Published: November 2009

Optical interferometry was used to study rough surfaces under lubricated point contact. Three dimensional “asperities” of chromium were sputtered onto a steel ball which was run against a smooth glass plate under both rolling and sliding. The experimental results were compared with the various published theories. The film thicknesses found in sliding are different from those observed in pure rolling, which are nearly equal to the theoretical values. Film thickness collapse occurred when the central film thickness/half asperity height ratio (λ ratio) reached a critical value.
Friction Reduction in Turbulent Journal Bearings by Highpolymers
Authors: Fukayama H. , Tanaka M. , Hori Y.
Published: November 2009

The friction reduction by dilute polymer solutions is investigated experimentally in turbulent journal bearings. The effects of polymer substances, polymer concentration, bearing clearance, and journal eccentricity on friction reduction are examined over the wide range of Reynolds number in the superlaminar regime. In the experiments, the friction of polymer solution is less than 40 percent of that of Newtonian turbulent flow under the best conditions. The calculated friction factor for the Couette flow is in good agreement with the corresponding measured one. Degradation of highpolymer is also investigated experimentally, and is found to be affected by polymer concentration.
Wear of Dynamically Loaded Hydrodynamic Bearings by Contaminant Particles
Authors: Ronen A. , Malkin S. , Loewy K.
Published: November 2009

An investigation is reported on the wear of hydrodynamic bearings by contaminant particles in the oil under dynamic loading conditions. A test bearing rig was developed to dynamically simulate an automotive connecting rod engine bearing, and the contaminant additions were of the types normally used for testing of automotive oil filters and air cleaners. Shaft and linear wear for clean and contaminated oil were measured both in terms of dimensional changes and weight loss at two different rotating speeds. As compared with clean oil, both shaft and linear wear were found to increase by typically a factor of 20 when running with the contaminated oil. A direct correlation was found between the local oil film thickness history and wear intensity for both the clean and contaminated oil. The wear tended to increase steeply at those locations where the oil film was smaller for a greater portion of the operating cycle.
The Simultaneous Effects of Thermal and Inertia in Curved Circular Squeeze Films
Authors: Gupta R. S. , Kapur V. K.
Published: November 2009

Interaction of thermal and inertia effects on squeeze film action for curved plates have been investigated. To illustrate the importance of the study, the numerical results obtained from the present theory for pressure drop for flat plates have been compared with the experimental results of Tichy and Winer which are in close agreement at 70°F. The behavior of the curvature of the film has also been illustrated in figures for load correction parameter.
Dynamic Stability of Externally Pressurized Gas Bearings
Authors: Blondeel E. , Snoeys R. , Devrieze L.
Published: November 2009

A feedback loop model is presented us to study instability phenomena in externally pressurized gas bearings. The main features in the theoretical analysis are the compressibility of the fluid and molecular transit times in the bearing gap. The proposed theory is based upon a separate handling of disturbances due to gap thickness variations and pressure changes. The analysis shows, that the dynamic pressure distribution in the gap plays an important role in the overall bearing stability. Comparisons between theoretical and experimental observations are highlighted; reference is made to Turnblade’s stability chart. The proposed analysis gives some additional information with regard to the relative importance of some bearing parameters.
Frontiers in Engineering Optimization
Authors: Betts J. T.
Published: November 2009

The successful application of a mathematical programming algorithm to a complex engineering problem requires a careful interfacing of needs and requirements between the optimization operator and the engineering system. This paper outlines some areas where interface requirements have not been successfully resolved. In order to bridge the frontier between theory and practice, issues are identified which require resolution by both algorithm developers and system engineers.
Nonlinear Integer Programming and Discrete Optimization
Authors: Gupta Omprakash K. , Ravindran A.
Published: November 2009

Branch and bound has been widely recognized as an effective method in solving linear integer programming problems. This paper presents a study on the feasibility of the branch and bound method in solving general nonlinear mixed integer programming and discrete optimization problems. First, a description of the branch and bound method as applied to the integer case is given. Next, a computer code BBNLMIP is developed to carry out an experimental study on 22 test problems. The numerical results indicate the effect of the problem parameters such as number of integer variables and constraints. Finally, a method for extending the branch and bound principle to solve nonlinear discrete optimization problems is described.
Accelerating Flexible Polyhedron Searches for Nonlinear Minimization
Authors: Townsend M. A. , Zarak C. E.
Published: November 2009

A new method is presented for determining the reflection point (centroid) which automatically varies the polyhedron (simplex or complex) moves to favor, in the early stages, a weighted move, and as the algorithm progresses, evolve to a more geometric move. Based on numerical experience to date, these attributes seem to be desirable for rapid progress throughout the algorithm stages.
Design of Drag-Link Mechanisms With Optimum Transmission Angle
Authors: Tsai Lung-Wen
Published: November 2009

In this paper, a new criterion for the design of a drag-link mechanism with optimum transmission angle is established. The transmission angle, the angle between the coupler link and output link of a four-bar linkage, is considered to be optimized when its extreme values deviate equally from 90 deg. Based on this criterion, design equations and design charts are developed. It is shown that the optimum drag-link mechanism is a turning-block linkage. It is also shown that to displace the drag-link mechanism with optimum transmission angle from its minimum lag to its maximum lag position, the input link must always rotate 180 deg and the corresponding angular displacement of the output link depends only on the link-length ratio of the output link to the fixed-link.
Development of an Optimum Variable-Stroke Internal-Combustion Engine Mechanism From the Viewpoint of Kinematic Structure
Authors: Freudenstein F. , Maki E. R.
Published: November 2009

The method of separation of kinematic structure and function has been used in the development of an optimum variable-stroke engine mechanism for automotive power plants. A systematic search procedure resulted in the structures of 39 mechanisms, one of which was judged optimal (U.S. Patent No. 4,270,495—reference [13]). The prior art, as disclosed in a number of patents and other publications, was evaluated and shown to be either included in the mechanisms created in the course of the search, or deliberately excluded by the search specification. The general nature of the approach, which combines mathematical and creative approaches, is believed to be useful in mechanical design.
Synthesis With Mixed Motion and Path Generation Position Specifications
Authors: Chuang J. C. , Waldron K. J.
Published: November 2009

Methods are developed for solving kinematic synthesis problems using precision position type methods for mixtures of motion generation and path generation type position specifications. All possible combinations of specification types for three or four design positions are considered.
An Experimental and Analytical Investigation of the Dynamic Response of a High-Speed Cam-Follower System. Part 1: Experimental Investigation
Authors: Pisano A. P. , Freudenstein F.
Published: November 2009

This paper is concerned with filling two gaps in the cam design field: (a) the absence of adequate measurements of the dynamic response of cam-follower systems, and (b) the need for the development of a predictive dynamic model for both normal and pathological system behavior. Part 1 presents the results of basic experiments on the dynamic response of a modern, high-speed cam-follower system. These data, which we believe to be the most comprehensive available in the open literature, and which are described more fully in [11], can be used by research investigators both in understanding system response and in developing and evaluating predictive dynamic models.
Boundary-Integral Equation Method Applied to Gear Strength Rating
Authors: Rubenchik V.
Published: November 2009

Employed is a new version of boundary-integral equation methods of the elasticity theory. It gives precise, reliable and simple numerical solution of the plane problem of gear tooth strength rating. The solution and program are proposed for every-day design calculation.
Displacement Analysis of a Special Case of the 7R, Single-Loop, Spatial Mechanism
Authors: Albala Hiram , Pessen David
Published: November 2009

Based on the displacement equations for the general n-bar, single-loop spatial linkage, obtained elsewhere, the displacement analysis for a special case of the 7R spatial mechanism is carried out. In this mechanism the successive rotation axes are perpendicular to each other, the distances between axes 3-4, 4-5, 5-6, are equal and the offsets along axes 4 and 5 are zero, when input axis is labeled axis 1. In this fashion, there still remain nine free linkage parameters. Input-output equation is of the eighth-degree in the tangent of half the output angle. A particular case of this one, where all the distances between axes are equal and all the offsets along axes are zero, leads to an input-output equation of the fourth-degree in the same quantity, with a maximum of four closures. This mechanism resulted to be a double-rocker.
Design Optimization of Machine-Tool Structures With Respect to Dynamic Characteristics
Authors: Yoshimura M. , Hamada T. , Yura K. , Hitomi K.
Published: November 2009

This paper proposes a design optimization method in which simplified structural models and standard mathematical programming methods are employed in order to optimize the dynamic characteristics of machine-tool structures in practical applications. This method is composed of three phases: (1) simplification, (2) optimization, and (3) realization. As design variables employed in this optimization are greatly reduced, machine-tool structures are optimized effectively in practice. With large design changes being conducted through this multiphase procedure, dynamic characteristics of machine tools can be greatly improved. This method is demonstrated on a structural model of a vertical lathe.
Automated Dynamic Analysis of Chain-Driven Mechanical Systems
Authors: Lee Ting W.
Published: November 2009

A general approach to analyze the dynamics of chain-driven systems subjected to transient loads is developed and applied. The method suitable for many automated dynamic analysis techniques involves the simulation of the dynamic effect of chain by a displacement function and the introduction of this function as a kinematic constraint to couple with the system equations of motion. A general purpose dynamic analysis algorithm, the DADS code (Dynamic Analysis and Design Systems), is then employed to generate the set of system equations and to provide a computer-aided dynamic analysis of the overall chain-driven system. Two ways of formulating the chain displacement functions are described. One provides the displacement of the chain based on the pitch circles of chain sprockets; the other includes a consideration of the polygonal effect of the chain which contributes essentially to the dynamics of the chain. The latter involves the use of the principle of kinematic equivalency, i.e., modeling the chain dynamic effect by a four-bar linkage. Using the proposed displacement function, the kinematic motion of the chain can be taken into account. This procedure, therefore, makes the system adaptable to conventional dynamic analysis code in which the chain is usually not included as one of the standard elements. Moreover, pulsation and dynamic load of the chain as well as the system dynamic response due to chain effect may be estimated. A typical large-scale chain-driven system which is an externally powered machine gun is investigated to illustrate the potential usefulness of the approach.
A Two-Dimensional Isoparametric Galerkin Finite Element for Acoustic-Flow Problems
Authors: Ling S.-F. , Hamilton J. F. , Allen J. J.
Published: November 2009

In duct acoustics, analytical solutions are difficult to obtain because of the presence of flow, boundary impedance, and complicated geometry. A Galerkin isoparametric finite element based on a domain equation which is uncoupled from the flow field is developed. Applying the method to duct acoustic problems results in a set of complex, unsymmetric, nondiagonal dominant simultaneous equations of high order. The Crout reduction scheme is modified to alleviate the computer storage difficulties in solving the numerical problem. The finite element is applied to the analysis of a semi-infinite duct with flow, and a convergent-divergent duct with flow.
Contact Pattern and Transmission Quality Analysis of Point Contact Conjugation With One Degree-of-Freedom
Authors: Chen Chih-Hsin
Published: November 2009

The kinematics of the point contact conjugation between two conjugate surfaces with one degree of freedom has long been an interesting problem, but not yet thoroughly solved. Nowadays, this problem is not only a problem with theoretical interest, but also a practical problem confronted in modern mechanical design. In this paper, on the ground of the author’s Theory Of Conjugate Surfaces [1, 2, 3,], the theoretical basis of the general solution of this problem is concisely presented, and an outline of the computation procedure for the solution is narrated.
Stress Analysis of Mechanical Sheaves and Pulleys
Authors: Saraph M. , Midha A. , Wambold J. C.
Published: November 2009

Sheaves and pulleys of various shapes and sizes are frequently employed in the mechanical transmission of power. The conventional design of sheaves is based on either empirical formulae or very elementary stress analysis. This paper presents a three-dimensional finite element stress analysis of a sheave and describes a preprocessor developed here, capable of generating data for sheaves of various configurations. Due to pecularities of their geometry and loading, the models are built using eight-node and twelve-node isoparametric brick elements. The preprocessor requires as few as twenty cards for generating data for any of the seven sheave models incorporated in the model library. Excellent correlation of results is obtained, when strains thus generated are compared with those experimentally available for a specific sheave type under loading.