bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of poor bowel preparation on colonoscopy: a prospective single centre study of 10 571 colonoscopies
Authors: Hendry P. O. , Jenkins J. T. , Diament R. H.
Published: March 2007

Objective  Colonoscopy is regarded as the most sensitive method of evaluating the colon. Inadequate preparation reduces sensitivity and has adverse implications for individual patients and the Heath Service.

Method  Data concerning the adequacy of bowel preparation and colonoscopy completion rates were prospectively collected on all colonoscopies performed in a single centre between January 1996 and January 2005. In addition, the strategy of further investigation in the event of incomplete examination was assessed.

Results  A total of 10 571 colonoscopies were assessed and poor bowel preparation was identified in 1788 of these cases (16.9%). The completion rate was 67.5% in those with satisfactory preparation. In patients with poor preparation, 36% of colonoscopies were complete. Incomplete examination was more likely with poor preparation [OR = 3.76 (95% CI, 3.38–4.18), P = 0.0005]. Poor preparation was more likely for inpatients [OR = 3.54 (95% CI 3.14–3.96), P = 0.0005]. Even with satisfactory preparation, inpatient completion rates were significantly less [OR = 1.78 (95% CI, 3.14–3.96), P = 0.0005). A further 542 diagnostic procedures were undertaken in the poor preparation group, an additional £101 950 (€149 459) in expenditure.

Conclusion  This study supports the view that inpatients fare badly. This is partly explained by higher rates of poor preparation; however, completion rates were reduced even with adequate preparation. Failed investigation and prolonged hospital stay increase cost. Colonoscopy completion rates need to be improved with particular attention to inpatients.
The impact of surgeon and pathologist on lymph node retrieval in colorectal cancer and its impact on survival for patients with Dukes’ stage B disease
Authors: Evans M. D. , Barton K. , Rees A. , Stamatakis J. D. , Karandikar S. S.
Published: March 2007

Objective  An adequate lymph node harvest is necessary for accurate Dukes’ stage discrimination in colorectal cancer. The aim of this study is to identify the effect of variables, including the individual surgeon and pathologist, on lymph node harvest in a single institution.

Method  Three hundred and eighty one consecutive patients had resection for colorectal cancer, in a single unit. Factors influencing lymph node retrieval, including individual surgeon and reporting pathologist, were subjected to uni‐ and multivariate analysis. Actuarial survival of all patients with Dukes’ stage B and C disease was then calculated and survival compared between Dukes’ stage B and C at differing levels of lymph node harvest.

Results  The unit median lymph node harvest was 13 nodes/patient (95% CI 13.1–14.5). There was no difference in lymph node harvest between specialist colorectal surgeons and the pooled results of four nonspecialist consultant surgeons. However, there was a significant difference between reporting pathologists (P < 0.001). On univariate analysis, operation type, operative urgency, Dukes’ stage, T‐stage, reporting pathologist and use of neoadjuvant therapy in rectal cancer, were found to significantly affect lymph node retrieval. On multivariate analysis, operation type, T‐stage, reporting pathologist and neoadjuvant therapy in rectal cancer remained significant variables. Patients with one or more lymph node metastasis had greater nodal harvests than those without (median 15 vs 12 P = 0.02). Survival of patients with Dukes’ stage B disease was found to improve as lymph node harvest increased.

Conclusion  Overall lymph node harvest, in this unit, varied according to the reporting pathologist but not operating surgeon. As lymph node harvest increased to 15 per patient, the probability of identifying a metastatic node increased.
HOTELLING'S BEACH WITH LINEAR AND QUADRATIC TRANSPORTATION COSTS: EXISTENCE OF PURE STRATEGY EQUILIBRIA*
Authors: EGLI ALAIN
Published: March 2007

In Hotelling type models consumers have the same transportation cost function. We deviate from this assumption and introduce two consumer types. Some consumers have linear transportation costs, while the others have quadratic transportation costs. If at most half the consumers have linear transportation costs, a subgame perfect equilibrium in pure strategies exists for all symmetric locations. Furthermore, no general principle of differentiation holds. With two consumer types, the equilibrium pattern ranges from maximum to intermediate differentiation. The degree of product differentiation depends on the fraction of consumer types.
SYMPOSIUM ON CHANGING MODES OF GOVERNANCE IN PUBLIC SECTOR ORGANIZATIONS: ACTION AND RHETORIC
Authors: DENT MIKE , VAN GESTEL NICOLETTE , TEELKEN CHRISTINE
Published: March 2007

This symposium grew out of the sub‐theme, ‘New Modes of Governance in Public Sector Organizations’, of the European Group for Organizational Studies (EGOS) Conference held in Ljubljana in July 2004. Our aim was to provide a forum to discuss the policy and practice and the space between in public sector management and governance within Europe.
SAVINGS IN THE ABSENCE OF FUNCTIONING PROPERTY RIGHTS1
Authors: Silver Nick , Acquaah Emmanuel , Juurikkala Oskari
Published: March 2007

Nigeria is a prime example of a developing country with ill‐defined property rights. However, people still manage to save, mostly through traditional and informal means, facilitated by strong family and community institutions. This paper argues that the government should concentrate on strengthening these institutions rather than weakening them by imposing an inappropriate, Western‐style, formal pensions system on the country.
Cytochrome P450 2B6 (CYP2B6) G516T influences nevirapine plasma concentrations in HIV‐infected patients in Uganda
Authors: Penzak SR , Kabuye G , Mugyenyi P , Mbamanya F , Natarajan V , Alfaro RM , Kityo C , Formentini E , Masur H
Published: March 2007

Objectives

Polymorphisms in the cytochrome P450 (CYP) 2B6 gene have been shown to influence nevirapine plasma concentrations in HIV‐infected European Caucasians. Although nevirapine is used extensively in Africa, the influence of CYP2B6 genotype on nevirapine exposure has not been assessed in this population. We aimed to determine the influence of CYP2B6 genotype at position 516 on nevirapine trough concentrations in HIV‐infected patients in Kampala, Uganda. Additional polymorphisms in the CYP and multidrug resistance protein‐1 (MDR‐1) genes were also assessed for their impact on nevirapine concentrations.

Methods

The following genotypes were determined in all subjects using polymerase chain reaction–restriction fragment length polymorphism: CYP2B6 G516T, MDR‐1 C3435T and G2677T, CYP3A4*1B and CYP3A5*3. Nevirapine plasma concentrations were determined using high‐performance liquid chromatography in 23 HIV‐infected patients who were generally healthy and had been taking nevirapine 200 mg twice daily for at least 14 days. Analysis of variance with post hoc testing was used to compare nevirapine concentrations among CYP2B6 genotype groups.

Results

The median nevirapine trough concentration in individuals homozygous for the variant allele (TT) was 7607 ng/mL vs 4181 and 5559 ng/mL for GG and GT individuals, respectively (GG vs TT median ratio=1.82;P=0.011). The mean ratio for TT vs GG individuals (95% confidence interval) was 1.51 (1.18, 1.84). No associations were observed between the other polymorphisms studied and nevirapine concentrations.

Conclusions

CYP2B6 G516T significantly influenced nevirapine trough concentrations in HIV‐infected patients in Uganda. Additional studies in larger patient populations are necessary to further define the potential clinical impact of these preliminary findings.
HIV‐associated Isospora belli infection: incidence and risk factors in the French Hospital Database on HIV
Authors: Guiguet M , Furco A , Tattevin P , Costagliola D , Molina J‐M ,   the French Hospital Database on HIV Clinical Epidemiology Group
Published: March 2007

Objective

To determine the incidence of Isospora belli infection in HIV‐infected patients in France, and to study risk factors.

Methods

The French Hospital Database on HIV (FHDH) is a prospective cohort study that collects demographic, clinical and therapeutic data on patients managed in 62 hospitals. We reviewed all cases of I. belli infection recorded between 1992 and 2003. We compared the incidence in 1992–1994 [before the use of dual therapy and combination antiretroviral therapy (cART)] and in 1997–2003 (when use of cART was widespread), after stratification for CD4 cell count (< 50, 50–99, 100–199 and > 200 cells/μL).

Results

A total of 164 patients had I. belli infection either at enrolment (n=71) or during follow up (n=93). During the study period, I. belli infection tended to occur less frequently during follow up, and to be diagnosed mainly at database enrolment. The incidence of I. belli infection during follow up fell by 79% [relative hazard (RH) 0.21; 95% confidence interval (CI) 0.13–0.33] in the cART period compared with the pre‐cART period; no such change was noted among patients with CD4 cell counts below 50 cells/μL. In multivariable analysis, the risk of I. belli infection was significantly higher among patients from sub‐Saharan Africa (RH 4.3; 95% CI 2.6–7.3). After adjustment for CD4 cell count, patients receiving cotrimoxazole prophylaxis were found to be at a lower risk of I. belli infection (RH 0.3; 95% CI 0.2–0.6).

Conclusions

In France, I. belli infection among HIV‐infected patients is now mainly seen in patients from sub‐Saharan Africa, who present at an advanced stage.
Validity of General Mental Ability for the Prediction of Job Performance and Training Success in Germany: A meta‐analysis1
Authors: Hülsheger Ute R. , Maier Günter W. , Stumpp Thorsten
Published: March 2007

A meta‐analysis into the operational validity of general mental ability (GMA) measures in Germany is presented. The meta‐analysis addresses the question whether findings of US and European meta‐analyses are generalizable to Germany given the differences in the education systems of these countries. The high level of differentiation in the German educational system is expected to enhance the homogeneity of applicant pools resulting in a low level of variability in predictor scores which reduces the observed GMA–performance relationships. Our analysis is based on 54 independent German articles and unpublished reports. Results indicated an operational validity of ρ=.467 for training success (k=90; N=11,969) and ρ=.534 for job performance (k=9; N=746). Moderator analyses showed that job complexity and the year of publication are relevant moderator variables, with lower job complexity levels and older studies being associated with higher operational validities. Findings suggest that overall German operational validities are comparable with findings in the United States or other European countries. However, for training success operational GMA validities are slightly lower in Germany compared with US or European meta‐analyses.
Incremental Validity of Situational Judgment Tests for Task and Contextual Job Performance
Authors: O'Connell Matthew S. , Hartman Nathan S. , McDaniel Michael A. , Grubb Walter Lee , Lawrence Amie
Published: March 2007

This paper has three goals. First, it responds to calls for additional research on subgroup differences in situational judgment tests. Second, it expands the cumulative knowledge on the incremental validity of situational judgment tests beyond cognitive ability and personality. Third, it examines the validity and incremental validity of various predictors for both task and contextual performance.
Evidence of Predictive and Incremental Validity of Personality Factors, Vocal Attractiveness and the Situational Interview
Authors: DeGroot Timothy , Kluemper Donald
Published: March 2007

This study evaluates the impact of the situational interview, personality measures, vocal attractiveness, and interactions between personality and vocal attractiveness on job performance. In a concurrent validity study with 154 customer service employees, a structured, situational interview was conducted and three of the Big Five personality factors (agreeableness, conscientiousness, and extraversion) are measured with two different frames‐of‐reference: at‐work and typical. Among the results are the validity of the situational interview and at‐work personality measures is established; vocal attractiveness correlates with both interview ratings and job performance; and finally, agreeableness and conscientiousness are found to vary in a pattern related to levels of vocal attractiveness such that both personality factors predict performance more strongly for people with more attractive voices.
Carotid intima–media thickness in HIV patients treated with antiretroviral therapy
Authors: Lebech Anne‐Mette , Wiinberg Niels , Kristoffersen Ulrik Sloth , Hesse Birger , Petersen Claus Leth , Gerstoft Jan , Kjær Andreas
Published: March 2007

Introduction:  Increased cardiovascular risk in HIV patients in antiretroviral therapy (ART) may be due to HIV infection, direct effect of ART or dyslipidaemia induced by ART. Our aim was to study the relative importance of HIV, ART and dyslipidaemia on atherosclerosis, assessed by the comparison of carotid artery intima–media thickness (IMT) in non‐smoking HIV patients with high or low serum cholesterol levels as well as in healthy volunteers.

Methods : HIV patients in ART with normal cholesterol (≤5·5 mmol l−1; n = 13) or high cholesterol (≥6·5 mmol l−1; n = 12) as well as healthy controls (n = 14) were included. All were non‐smokers and had never received medication for dyslipidaemia or hypertension. IMT was measured by ultrasonography.

Results : In HIV patients with normal cholesterol (≤5·5 mmol l−1), in HIV patients with hypercholesterolaemia (≥6·5 mmol l−1) and in controls (5·1 ± 0·9 mmol l−1) IMT were 683 ± 119, 656 ± 99 and 657 ± 99 μm, respectively. Thus no difference in IMT was found between the three groups. IMT values did not differ between patients receiving and not receiving protease inhibitors (658 ± 117 μm versus 687 ± 97 μm, P>0·05). In HIV patients IMT correlated inversely with HDL cholesterol levels (r = −0·50; P = 0·01), whereas no correlation was found with total cholesterol or LDL cholesterol.

Conclusions : In non‐smoking HIV patients receiving ART no sign of accelerated atherosclerosis was found as assessed by IMT even not in hypercholesterolaemic HIV patients. IMT correlated with HDL cholesterol but not with LDL cholesterol. Based on these observations, one could speculate whether selective lowering of LDL cholesterol will be successful in reducing cardiovascular risk in non‐smoking HIV patients.
Even Lawyers Get the Blues: Gender, Depression, and Job Satisfaction in Legal Practice
Authors: Hagan John , Kay Fiona
Published: March 2007

It is an intriguing puzzle that women lawyers, despite less desirable working conditions and blocked career advancement, report similar satisfaction as men lawyers with their legal careers. The paradoxical work satisfaction reported by women and men lawyers obscures a more notable difference in their depressed or despondent feelings. Using a panel study of women and men lawyers practicing in Toronto since the mid-1980s, we find at least three causal pathways through which gender indirectly is connected to job dissatisfaction and feelings of despondency. The first path is through gender differences in occupational power, which lead to differential despondency. The second path is through differences in perceived powerlessness, which directly influence job dissatisfaction. The third path is through feelings of despondency that result from concerns about the career consequences of having children. The combined picture that results illustrates the necessity to include measures of depressed affect in studies of dissatisfaction with legal practice. Explicit measurement and modeling of concerns about the consequences of having children and depressed feelings reveal a highly gendered response of women to legal practice that is otherwise much less apparent. Women are more likely to respond to their professional grievances with internalized feelings of despondency than with externalized expressions of job dissatisfaction. That is, they are more likely to privatize than publicize their professional troubles.
Ethnic In‐Group Favoritism Among Minority and Majority Groups: Testing the Self‐Esteem Hypothesis Among Preadolescents
Authors: Verkuyten Maykel
Published: March 2007

The self‐esteem hypothesis in intergroup relations, as proposed by social identity theory (SIT), states that successful intergroup discrimination enhances momentary collective self‐esteem. This hypothesis is a source of continuing controversy. Furthermore, although SIT is increasingly used to account for children's group attitudes, few studies have examined the hypothesis among children. In addition, the hypothesis's generality makes it important to study among children from different ethnic groups. The present study, conducted among Dutch and Turkish preadolescents, examined momentary collective self‐feelings as a consequence of ethnic group evaluations. The results tended to support the self‐esteem hypothesis. In‐group favoritism was found to have a self‐enhancing effect among participants high in ethnic identification. This result was found for ethnic majority (Dutch) and minority (Turkish) participants.
Church Attendance and Marital Commitment Beliefs of Undergraduate Women
Authors: Hui Siu‐kuen Azor , Lindsey Cynthia R. , Elliott Timothy R.
Published: March 2007

Marital commitment between spouses has been found to be an important predictor of successful marriages. Beliefs about marital commitment among never‐married young adults are of interest because of their probable influence on subsequent marital behaviors. The current study examined social‐cognitive processes; specifically, religiousness, locus‐of‐control beliefs, and gender role attitudes, in the prediction of marital commitment beliefs among 294 undergraduate never‐married women. We found that higher religiousness and lower chance locus of control were significantly correlated with stronger marital commitment beliefs. Multiple regression analyses revealed that religiousness was the best predictor of marital commitment beliefs in this sample. Social learning processes are implicated in the development of marital commitment beliefs. Implications and limitations of the study are discussed.
The Moderating Role of Ethnic Identity and Social Support on Relations Between Well‐Being and Academic Performance1
Authors: Cole Barbara , Matheson Kimberly , Anisman Hymie
Published: March 2007

The role of social support and ethnic identity in moderating the effects of factors that may emanate from stereotype threat on academic performance was examined. Depressive and anxiety symptoms of ethnic minority (n = 65) and Euro‐Caucasian students (n = 198) were tracked through their first year of university. Although students' symptoms did not differ at the outset of the year, higher symptoms uniquely evident among ethnic minority students at midyear were associated with poorer final grades, and reduced well‐being was sustained at the end of the year. Social support from friends and fewer unsupportive interactions predicted greater success among ethnic minority students. Although both groups benefited from academic support, such support was perceived as less available to minority students.
Effects of amino nitrogen on fermentation parameters by mixed ruminal microbes when energy or nitrogen is limited
Authors: KAJIKAWA Hiroshi , TAJIMA Kiyoshi , MITSUMORI Makoto , TAKENAKA Akio
Published: March 2007

Ruminal microbes harvested from a ruminally fistulated cow were incubated in simple batch and semicontinuous cultures with NH3‐N or amino‐N on nitrogen‐ or energy‐excess diets in quantity (HN and LN diets, respectively, consisting of timothy hay plus soybean meal, or corn grain), based on evaluation with the National Research Council and Cornell Net Carbohydrate and Protein System models. In a batch culture experiment, supplementation with amino‐N promoted digestion and fermentation in the course of incubation (4–24 h) on both diets, but these effects mostly disappeared when the diets were sufficiently digested (at 48 h). In a semicontinuous culture experiment using Rusitec, no effect of amino‐N was exhibited after sufficient fermentation and digestion, but significant promotion of digestion was shown in the course of incubation on the HN diet, while no such effect was detected on the LN diet. The microbial yield for 24 h did not show a significant difference between the N sources of either of the two diets. These results suggest that the stimulatory effects of amino‐N are diminished when the diets are sufficiently digested after a long retention and incubation, and also that the effectiveness of amino‐N does not require a quantitatively energy‐excess status.
Advanced molecular immunoassay system for immunobiotic lactic acid bacteria using a transfectant of Toll‐like receptor 2
Authors: TOHNO Masanori , SHIMOSATO Takeshi , KAWAI Yasushi , ASO Hisashi , IKEGAMI Shuji , TAKETOMO Naoki , SAITO Tadao , KITAZAWA Haruki
Published: March 2007

Toll‐like receptor 2 (TLR2) is a receptor for a variety of microbial components, and it also mediates activation signals in the cell relating to the innate immune system. In order to evaluate the precise molecular immunoregulation by various strains of lactic acid bacteria (LAB) via TLR2, the swine TLR2 (sTLR2)‐expressing transfectant was constructed using human embryonic kidney (HEK) 293 cells. It is demonstrated that intact immunobiotic LAB can induce immune responses through TLR2, and that different nuclear factor‐κB (NF‐κB) activities of various strains can be accurately detected by sTLR2‐expressing HEK293 cells. Furthermore, cellular activation of NF‐κB via TLR2 is reflected in enhanced binding and uptake of LAB. The sTLR2‐expressing HEK293 cells were also useful for characterizing the expression pattern of type I helper T (Th1) and type II helper T (Th2) cytokines by the stimulation of immunobiotic LAB. These results suggest that sTLR2‐expressing HEK293 cells may be useful in certain molecular immunoassay systems for producing new physiologically functional foods with intestinal immunomodulatory abilities, such as the maintenance of Th1/Th2 polarization.
Overweight and obesity among affluent Bengalee schoolgirls of Lake Town, Kolkata, India
Authors: Bose Kaushik , Bisai Samiran , Mukhopadhyay Ashish , Bhadra Mithu
Published: March 2007

A cross‐sectional study was undertaken to determine the prevalence of overweight and obesity among 431 Bengalee schoolgirls aged 6–9 years in Kolkata, India. Anthropometric measurements of height and weight were made on 431 girls. The body mass index (BMI) was computed following the standard equation. Overweight and obesity was defined following the internationally accepted BMI cut‐off points. Results revealed that the overall rates of overweight and obesity were 17.63% and 5.10%, respectively. A steady increase in number of overweight individuals was observed from 6 to 9 years. The prevalence of overweight among affluent Bengalee children was higher than those reported from other Asian countries.
A survey of neonatal nutrition policies and practices in the UK and Eire
Authors: Tuthill David P. ,   Child Nutrition Panel
Published: March 2007

Optimal nutrition is one of the fundamental components for infants to reach their full growth and neurodevelopmental potential. Best practice is facilitated by a contemporaneous, multidisciplinary, evidence‐based nutrition policy. Such evidence has recently been reviewed. We have assessed: the prevalence of nutrition policies in neonatal units in the UK and Eire; their application to hypothetical cases; the availability of dietetic input; and whether any differences existed between non‐regional and regional units. A standardized questionnaire was devised by a multidisciplinary group and posted to all 255 neonatal units in the UK and Eire in 2002. Replies from 67 neonatal units were received: 48 out of 233 non‐regional and 19 out of 22 regional units. A feeding policy was present in 33 units, and regular access to dietitians occurred in 37 units. For a hypothetical infant less than 28 weeks’ gestation, enteral feeds would be commenced at 0–2 days in 81% of non‐regional and 94% of regional units (P = ns), and be continuous in 11% of non‐regional and 32% of regional units, and bolus feeding in 89% of non‐regional and 68% of regional units (P = ns). Routine fortification of breastmilk would occur more frequently in non‐regional units (96%) than in regional units (79%) (P = 0.050). Vitamin and iron supplements would be given to infants receiving postdischarge or high‐energy milks in 68% of non‐regional units and in 79% of regional units (P = ns). Calorie counts (63% regional vs. 8% non‐regional, P < 0.001), and daily weights (68% regional vs. 33% non‐regional, P = 0.014), were used more frequently in regional units. Many units surveyed did not have a nutrition policy. Many infants receive unnecessary additional vitamins and supplements. Practice is variable throughout the country, but we found no evidence of major differences between regional and non‐regional units, apart from their monitoring of growth and rates of breastmilk fortifier usage.
CARD15 variants determine a disturbed early response of monocytes to adherent‐invasive Escherichia coli strain LF82 in Crohn's disease
Authors: Peeters H. , Bogaert S. , Laukens D. , Rottiers P. , De Keyser Filip , Darfeuille‐Michaud A. , Glasser A.‐L. , Elewaut D. , De Vos M.
Published: March 2007

Caspase activation and recruitment domain 15 (CARD15) and Toll‐like receptor 4 (TLR4) are respectively intracellular and membrane‐bound receptors for bacterial cell wall components [respectively muramyl dipeptide (MDP) and lipopolysaccharide (LPS)]. Polymorphisms in CARD15 and TLR4 have been linked with Crohn's disease (CD). Adherent‐invasive Escherichia coli (AIEC) strains with particular adhesion and invasion characteristics have been specifically associated with CD ileal mucosa. The aim of this study was to investigate the functional impact of these polymorphisms on monocytes in patients with CD, in response to MDP, LPS and AIEC strain LF82. Monocytes were isolated from 40 patients with CD using magnetic cell sorting, stimulated with LPS or MDP or infected with AIEC. IL‐1β, IL‐6, IL‐8, IL‐10, IL‐12 and tumour necrosis factor alpha induction was assessed using quantitative real time–polymerase chain reaction, Cytometric Bead Array and ELISA. Bacterial intracellular survival and replication was assessed using a gentamicin protection assay. Results were linked with the presence of CARD15 and TLR4 polymorphisms. Monocytes of patients with CARD15 polymorphisms showed an early reduced cytokine response (IL‐1β, IL‐6 and IL‐10) to infection with AIEC, which was restored after 20 h. A gene–dose effect was seen, comparing wild‐types, heterozygotes and homozygotes. We found no differences in intracellular survival and replication of AIEC. Heterozygous carriage of TLR4 polymorphisms did not influence monocyte response. In conclusion, patients with CD carrying CARD15 polymorphisms show a disturbed early inflammatory monocyte response after infection with AIEC strain LF82. For the first time, a functional defect was detected in single heterozygous carriers. These findings reflect the potential role of a genetically altered host response to disease‐related bacteria in the pathogenesis of CD.
An Extension of Hertz’s Theory in Contact Mechanics
Authors: Fu Guanghui
Published: March 2007

Hertz’s theory, developed in 1881, remains the foundation for the analysis of most contact problems. In this paper, we consider the axisymmetric normal contact of two elastic bodies, and the body profiles are described by polynomial functions of integer and noninteger positive powers. It is an extension of Hertz’s solution, which concerns the contact of two elastic spheres. A general procedure on how to solve this kind of problem is presented. As an example, we consider the contact between a cone and a sphere. The relations among the radius of the contact area, the depth of the indentation, the total load, and the contact pressure distribution are derived.
The Dual Euler Basis: Constraints, Potentials, and Lagrange’s Equations in Rigid-Body Dynamics
Authors: O'Reilly Oliver M.
Published: March 2007

Given a specific set of Euler angles, it is common to ask what representations conservative moments and constraint moments possess. In this paper, we discuss the role that a non-orthogonal basis, which we call the dual Euler basis, plays in the representations. The use of the basis is illustrated with applications to potential energies, constraints, and Lagrange’s equations of motion.
Dynamic T-Stress for a Mode-I Crack in an Infinite Elastic Plane
Authors: Li Xian-Fang
Published: March 2007

An integral equation method is presented to determine dynamic elastic T-stress. Special attention is paid to a single crack in an infinite elastic plane subjected to impact loading. By using the Laplace and Fourier transforms, the associated initial-boundary value problem is transformed to a Fredholm integral equation. The dynamic T-stress in the Laplace transform domain can be expressed in terms of its solution. Moreover, an explicit expression for initial T-stress is derived in closed form. Numerically solving the resulting equation and performing the inverse Laplace transform, the transient response of T-stress is determined in the time space, and the response history of the T-stress is shown graphically. Results indicate that T-stress exhibits apparent transient characteristic.
Nonlinear Stability of
the Classical Nusselt Problem of Film Condensation and Wave
Effects
Authors: Phan L. , Narain A.
Published: March 2007

Accurate steady and unsteady numerical solutions of the full two-dimensional (2D) governing equations for the Nusselt problem (film condensation of quiescent saturated vapor on a vertical wall) are presented and related to known results. The problem, solved accurately up to film Reynolds number of 60 (Reδ⩽60), establishes various features of the well-known steady solution and reveals the interesting phenomena of stability, instability, and nonlinear wave effects. It is shown that intrinsic flow instabilities cause the wave effects to grow over the well-known experiments-based range of Reδ⩾30. The wave effects due to film flow’s sensitivity to ever-present minuscule transverse vibrations of the condensing surface are also described. The results suggest some ways of choosing wall noise—through suitable actuators—that can enhance or dampen wave fluctuations and thus increase or decrease heat transfer rates over the laminar-to-turbulent transition zone.
Application of
Minature Ring-Core and Interferometric Strain/Slope Rosette to Determine Residual Stress
Distribution With Depth—Part I: Theories
Authors: Li Keyu , Ren Wei
Published: March 2007

The principle of an interferometric strain/slope rosette (ISSR) is based on interference of laser beams reflected from three microindentations on a specimen surface. The ISSR can simultaneously measure the in-plane strains and the out-of-plane slopes. Ring-core cutting is a mechanical stress relief method. When used with the ISSR technique for residual stress measurement, the ring core can be made much smaller than used with the resistance strain rosette. Thus, more localized residual stresses can be measured. The theories of the ISSR/ring-core cutting method are described in this paper. Both mechanical and finite element models are developed for the incremental ring-core cutting process with the application of the ISSR technique. The stress-strain coefficients of the ISSR/ring-core method are calculated and nondimensionalized for general applications. A test example is given to demonstrate how residual stress distribution is determined by using the stress-strain coefficients and the ISSR data.
Application of Miniature Ring-Core and Interferometric Strain/Slope Rosette to Determine Residual Stress Distribution With Depth—Part II: Experiments
Authors: Ren Wei , Li Keyu
Published: March 2007

The theoretical development of the interferometric strain/slope rosette (ISSR) and ring-core cutting method is described in Part I of the paper [K. Li and W. Ren, ASME J. Appl. Mech. 74(2), 298–306 (2007)]. In Part II, experiments are presented to demonstrate the applicability of the method. The procedures of experimentation are developed. An ISSR/ring-core cutting system was established and its measurement stability and accuracy were examined in a two-step measurement program. By repeating the two-step measurement procedures, several incremental ring-core cutting experiments were conducted. Residual stress distribution is calculated from the measured ISSR data by using the relaxation coefficients calibrated in Part I of the paper. Measurement resolution, accuracy, and sensitivity of the ISSR/ring-core method are evaluated. Tests on a titanium block show the reliability of the method in comparison with the results obtained by using other measurement methods. The new method is also applied on a laser weld which demonstrates its uniqueness to measure residual stresses in small areas with high stress gradients. The experiments show advantages of the ISSR/ring-core method, such as miniature size, noncontacting nature, and high sensitivity. The method can be effectively used to measure residual stress distributions with depth on various manufactured components.
Quasi-Periodic Response Regimes of Linear Oscillator Coupled to Nonlinear Energy Sink Under Periodic Forcing
Authors: Gendelman O. V. , Starosvetsky Yu.
Published: March 2007

Quasi-periodic response of a linear oscillator attached to nonlinear energy sink with relatively small mass under external sinusoidal forcing in a vicinity of main (1:1) resonance is studied analytically and numerically. It is shown that the quasi-periodic response is exhibited in well-defined amplitude-frequency range of the external force. Two qualitatively different regimes of the quasi-periodic response are revealed. The first appears as a result of linear instability of the steady-state regime of the oscillations. The second one occurs due to interaction of the dynamical flow with invariant manifold of damped-forced nonlinear normal mode of the system, resulting in hysteretic motion of the flow in the vicinity of this mode. Parameters of external forcing giving rise to the quasi-periodic response are predicted by means of simplified analytic model. The model also allows predicting that the stable quasi-periodic regimes appear for certain range of damping coefficient. All findings of the simplified analytic model are verified numerically and considerable agreement is observed.
Mechanical Steering Compensators for High-Performance Motorcycles
Authors: Evangelou Simos , Limebeer David J. N. , Sharp Robin S. , Smith Malcolm C.
Published: March 2007

This paper introduces the idea of using mechanical steering compensators to improve the dynamic behavior of high-performance motorcycles. These compensators are seen as possible replacements for a conventional steering damper and comprise networks of springs, dampers, and a less familiar component called the inerter. The inerter was recently introduced to allow the synthesis of arbitrary passive mechanical impedances, and finds a potential application in the present work. The design and synthesis of these compensation systems make use of the analogy between passive electrical and mechanical networks. This analogy is reviewed alongside the links between passivity, positive reality, and network synthesis. Compensator design methods that are based on classical Bode-Nyquist frequency-response ideas are presented. Initial designs are subsequently optimized using a sequential quadratic programing algorithm. This optimization process ensures improved performance over the machine’s entire operating regime. The investigation is developed from an analysis of specific mechanical networks to the class of all biquadratic positive real functions. This aspect of the research is directed to answering the question: “What is the best possible system performance achievable using any simple passive mechanical network compensator?” The study makes use of computer simulations, which exploit a state-of-the-art motorcycle model whose parameter set is based on a Suzuki GSX-R1000 sports machine. The results show that, compared to a conventional steering damper, it is possible to obtain significant improvements in the dynamic properties of the primary oscillatory modes, known as “wobble” and “weave.”
The Underwater Blast Resistance of Metallic Sandwich Beams With Prismatic Lattice Cores
Authors: McShane G. J. , Deshpande V. S. , Fleck N. A.
Published: March 2007

The finite element method is used to evaluate the underwater blast resistance of monolithic beams and sandwich beams containing prismatic lattice cores (Y-frame and corrugated core) and an ideal foam core. Calculations are performed on both free-standing and end-clamped beams, and fluid-structure interaction effects are accounted for. It is found that the degree of core compression in the free-standing sandwich beam is sensitive to core strength, yet the transmitted impulse is only mildly sensitive to the type of sandwich core. Clamped sandwich beams significantly outperform clamped monolithic beams of equal mass, particularly for stubby beams. The Fleck and Deshpande analytical model for the blast response of sandwich beams is critically assessed by determining the significance of cross-coupling between the three stages of response: in stage I the front face is accelerated by the fluid up to the point of first cavitation, stage II involves compression of the core until the front and back faces have an equal velocity, and in stage III the sandwich beam arrests by a combination of beam bending and stretching. The sensitivity of the response to the relative magnitude of these time scales is assessed by appropriately chosen numerical simulations. Coupling between stages I and II increases the level of transmitted impulse by the fluid by 20–30% for a wide range of core strengths, for both the free-standing and clamped beams. Consequently, the back face deflection of the clamped sandwich beam exceeds that of the fully decoupled model. For stubby beams with a Y-frame and corrugated core, strong coupling exists between the core compression phase (stage II) and the beam bending/stretching phase (stage III); this coupling is beneficial as it results in a reduced deflection of the back (distal) face. In contrast, the phases of core compression (stage II) and beam bending/stretching (stage III) are decoupled for slender beams. The significance of the relative time scales for the three stages of response of the clamped beams are summarized on a performance map that takes as axes the ratios of the time scales.
Comparison of three types of full-body compression garments on throwing and repeat-sprint performance in cricket players
Authors: Duffield Rob , Portus Marc
Published: March 2007

Objective:To compare the effects of three types of full-body compression garments (Skins, Adidas and Under Armour) on repeat-sprint and throwing performance in cricket players.

Methods:Following familiarisation, 10 male cricket players performed four randomised exercise sessions (3 garments and a control). Each session involved a 30 min repeat-sprint exercise protocol comprising 20 m sprints every minute, separated by submaximal exercise. Throwing tests included a pre-exercise and a postexercise maximal distance test and accuracy throwing tests. During each session, measures of heart rate, skin temperature, change in body mass, rate of perceived exertion and perceived muscle soreness were recorded. Capillary blood samples were analysed before and after exercise for lactate, pH, O2saturation and O2partial pressure, and 24 h after exercise for creatine kinase (CK). Ratings of perceived muscle soreness were also obtained 24 h after exercise.

Results:No significant differences (p>0.05) were evident in repeat-sprint performance (10 m, 20 m time or total submaximal distance covered) or throwing performance (maximum distance or accuracy). No significant differences (p>0.05) were observed in heart rate, body mass change or blood measures during exercise. Significant differences (p<0.05) were observed by way of higher mean skin temperature, lower 24 h postexercise CK values and lower 24 h postexercise ratings of muscle soreness when wearing compression garments. Analysis between respective brands of compression garments revealed no statistical differences (p>0.05).

Conclusions:No benefit was noted when wearing compression garments for repeat-sprint or throwing performance; however, the use of the garments as a recovery tool, when worn after exercise, may be beneficial to reduce postexercise trauma and perceived muscle soreness.
c-Myc and ChREBP regulate glucose-mediated expression of the L-type pyruvate kinase gene in INS-1-derived 832/13 cells
Authors: Jason Collier J. , Zhang Pili , Pedersen Kim B. , Burke Susan J. , Haycock John W. , Scott Donald K.
Published: March 2007

Increased glucose flux generates metabolic signals that control transcriptional programs through poorly understood mechanisms. Previously, we demonstrated a necessity in hepatocytes for c-Myc in the regulation of a prototypical glucose-responsive gene, L-type pyruvate kinase (L-PK) (Collier JJ, Doan TT, Daniels MC, Schurr JR, Kolls JK, Scott DK. J Biol Chem 278: 6588–6595, 2003). Pancreatic β-cells have many features in common with hepatocytes with respect to glucose-regulated gene expression, and in the present study we determined whether c-Myc was required for the L-PK glucose response in insulin-secreting (INS-1)-derived 832/13 cells. Glucose increased c-Myc abundance and association with its heterodimer partner, Max. Manipulations that prevented the formation of a functional c-Myc/Max heterodimer reduced the expression of the L-PK gene. In addition, glucose augmented the binding of carbohydrate response element binding protein (ChREBP), c-Myc, and Max to the promoter of the L-PK gene in situ. The transactivation of ChREBP, but not of c-Myc, was dependent on high glucose concentrations in the contexts of either the L-PK promoter or a heterologous promoter. The glucose-mediated transactivation of ChREBP was independent of mutations that alter phosphorylation sites thought to regulate the cellular location of ChREBP. We conclude that maximal glucose-induced expression of the L-PK gene in INS-1-derived 832/13 cells involves increased c-Myc abundance, recruitment of c-Myc, Max, and ChREBP to the promoter, and a glucose-stimulated increase in ChREBP transactivation.
Assessment of β-cell function in humans, simultaneously with insulin sensitivity and hepatic extraction, from intravenous and oral glucose tests
Authors: Cobelli Claudio , Toffolo Gianna Maria , Man Chiara Dalla , Campioni Marco , Denti Paolo , Caumo Andrea , Butler Peter , Rizza Robert
Published: March 2007

Assessment of insulin secretion in humans under physiological conditions has been a challenge because of its complex interplay with insulin action and hepatic insulin extraction. The possibility of simultaneously assessing β-cell function, insulin sensitivity, and hepatic insulin extraction under physiological conditions using a simple protocol is appealing, since it has the potential to provide novel insights regarding the regulation of fasting and postprandial glucose metabolism in diabetic and nondiabetic humans. In this Perspective, we review data indicating that an oral glucose tolerance test (OGTT) or a meal test is able to accomplish this goal when interpreted with the oral β-cell minimal model. We begin by using the well-established intravenous minimal model to highlight how the oral minimal model was developed and how the oral assessment parallels that of an intravenous glucose tolerance test (IVGTT). We also point out the unique aspects of both approaches in relation to their ability to assess different aspects of the β-cell secretory cascade. We review the ability of the oral model to concurrently measure insulin sensitivity and hepatic insulin extraction, thereby enabling it to quantitatively portray the complex relationship among β-cell function, hepatic insulin extraction, and insulin action. In addition, data from 204 individuals (54 young and 159 elderly) who underwent both IVGTT and meal tolerance tests are used to illustrate how these different approaches provide complementary but differing insights regarding the regulation of β-cell function in humans.
Neoangiogenesis and the presence of progenitor cells in the venous limb of an arteriovenous fistula in the rat
Authors: Caplice Noel M. , Wang Shaohua , Tracz Michal , Croatt Anthony J. , Grande Joseph P. , Katusic Zvonimir S. , Nath Karl A.
Published: March 2007

Venous injury and attendant venous stenosis are major contributors to the failure of hemodialysis vascular accesses. This report describes the presence of neoangiogenesis in the intima and adventitia of the venous limb of an arteriovenous (AV) fistula in the rat, the latter induced by creating an aortocaval fistula. Immunohistochemistry of the venous limb demonstrated the presence of c-Kit-positive cells lining new microvessels with lumen formation and that these c-Kit-positive cells exhibited either a smooth muscle phenotype as reflected by concomitant expression of calponin, or an endothelial phenotype as reflected by expression of endothelial nitric oxide synthase (eNOS). Western analysis confirmed upregulation of eNOS in the venous limb of the AV fistula. Measurement of systemic concentrations of angiogenic cytokines, namely, monocyte chemotactic protein-1, stromal cell-derived factor-1 (SDF-1), cytokine-induced neutrophil chemoattractant, and VEGF, failed to reveal an increase in these cytokines either at 3 or 10 wk after creation of the AV fistula. The angiogenic cytokines VEGF and SDF-1 were not upregulated in the venous limb of the AV fistula either at 2 or 16 wk. We conclude that in this model of an AV fistula in the rat, neoangiogenesis occurs and is constituted, at least in part, by bone marrow-derived cells, the latter differentiating to exhibit either an endothelial or smooth muscle phenotype. In view of these findings, we suggest that this model may offer an experimental approach by which to explore the evolution and significance of neoangiogenesis in the formation and pathobiology of vascular plaques, and the mechanisms that promote dysfunction of hemodialysis AV fistulas.
Functional polymorphism in human CYP4F2 decreases 20-HETE production
Authors: Stec David E. , Roman Richard J. , Flasch Averia , Rieder Mark J.
Published: March 2007

20-Hydroxyeicosatetraenoic acid (20-HETE) plays an important role in the regulation of renal tubular and vascular function and a deficiency in the renal formation of 20-HETE has been linked to the development of hypertension. The cytochrome P450 4F2 ( CYP4F2) gene encodes for the major CYP enzyme responsible for the synthesis of 20-HETE in the human kidney. We screened two human sampling panels (African and European Americans: n = 24 and 23 individuals, respectively) using PCR and DNA resequencing to identify informative SNPs in the coding region of the CYP4F2 gene. Two nonsynonymous SNPs that lead to amino acid changes at position 12 (W12G) and 433 (V433M), were identified. Both of these variants were found to be frequent in both African and European American sampling panels (9–21% minor allele frequency), and the W12G polymorphism exhibited extensive linkage disequilibrium with surrounding SNPs. To determine the functional significance of these mutations on the ability of the CYP4F2 enzyme to metabolize arachidonic acid and leukotriene B4(LTB4), recombinant baculoviruses containing four different human CYP4F2 variants (i.e., W12/V433, W12/M433, G12/V433, G12/M433) were generated and the proteins were expressed in Sf9 insect cells. The presence of the M433 allele, W12/M433, or G12/M433 decreased 20-HETE production to 56–66% of control. In contrast these variants had no effect on the ω-hydroxylation of LTB4. These findings are the first to identify a functional variant in the human CYP4F2 gene that alters the production of 20-HETE.