Showing papers by "Wichita State University published in 2000"

Educational and Vocational Aspirations of Minority and Female Students: A Longitudinal Study.

Abstract: This study examined the relative importance of school, family, personal/psychological, race, and sex variables in predicting educational and vocational aspirations. A nationally representative sample of 10th-grade students was followed through 2 years beyond their high school. Results suggested that sex and race significantly predicted educational and vocational aspirations of students. The educational aspiration model was shown to be more robust than the occupational aspiration model. Overall, students showed increases in educational and occupational aspirations, regardless of sex and race. Compared with other groups, Asian Americans had the greatest increase in educational aspirations. Female students, on the average, had higher educational and vocational aspirations.

Physical activity for the chronically ill and disabled.

Abstract: Exercise prescription principles for persons without chronic disease and/or disability are based on well developed scientific information. While there are varied objectives for being physically active, including enhancing physical fitness, promoting health by reducing the risk for chronic disease and ensuring safety during exercise participation, the essence of the exercise prescription is based on individual interests, health needs and clinical status, and therefore the aforementioned goals do not always carry equal weight. In the same manner, the principles of exercise prescription for persons with chronic disease and/or disability should place more emphasis on the patient's clinical status and, as a result, the exercise mode, intensity, frequency and duration are usually modified according to their clinical condition. Presently, these exercise prescription principles have been scientifically defined for clients with coronary heart disease. However, other diseases and/or disabilities have been studied less (e.g. renal failure, cancer, chronic fatigue syndrome, cerebral palsy). This article reviews these issues with specific reference to persons with chronic diseases and disabilities.

From recipient to contributor: examining customer roles and experienced outcomes

Abstract: In recent years, both management and marketing fields have emphasized the importance of a customer orientation. In this project, a different set of lenses is adopted to examine customer orientation from the customer’s point of view. Customers can enact four specific roles that enable them to create a partnership with human services firms. Customers can be important resources for the firm. They can actively participate in the firm’s activities as co‐producers of the service. As buyers, customers can develop a relationship with a service organization, and as recipients they register evaluations of their encounter. Analysis of an extensive survey of customer perceptions and investments in a firm’s activities provided an outside‐in look at customer orientation. The results present clear evidence that customers can influence the outcomes they experience. Avenues for future research and practical opportunities for managers to capitalize on their relationships with customers are discussed.

Models for Old, Metal-poor Stars with Enhanced α-Element Abundances. I. Evolutionary Tracks and ZAHB Loci; Observational Constraints

Abstract: Stellar evolutionary tracks have been computed for 17 [Fe/H] values from -2.31 to -0.30 assuming, in each case, [?/Fe] = 0.0, 0.3, and 0.6. The helium abundance was assumed to vary from Y = 0.2352 at [Fe/H] = -2.31 to Y = 0.2550 at [Fe/H] = -0.30 and held constant for the different choices of [?/Fe] at a fixed iron content. Masses in the range 0.5 ? ? ? 1.0, in 0.1 ? steps, were generally considered, though sequences for higher mass values were computed, as necessary, to ensure that isochrones as young as 8 Gyr could be generated for each grid. All of the stellar models are based on an equation of state that treats nonideal effects, the latest nuclear reaction and neutrino cooling rates, and opacities that were computed specifically for the adopted chemical mixtures. The tracks were extended to the tip of the giant branch or to an age of 30 Gyr, whichever came first, and zero-age horizontal-branch (ZAHB) loci were constructed using the helium core masses and chemical profiles from appropriate red giant precursors. Selected models have been compared with those computed by A. V. Sweigart, for the same masses and chemical compositions, to demonstrate that the results obtained from two entirely independent stellar evolution codes agree well with one another when very similar input physics is assumed. In the case of extremely metal-deficient stars, an enhancement in the abundance of the ?-elements causes a single, fairly significant bump in the opacity at a temperature just above 106 K, which is caused by absorption processes involving the K shell of oxygen. This peak becomes steadily more pronounced as the overall metallicity increases and a second bump, arising from the L edges of Ne, Mg, and Si, eventually appears near log T = 5.6. As far as the tracks and isochrones are concerned, we find that, as already reported by others, it is possible to mimic the computations for [?/Fe] > 0 remarkably well by those for scaled-solar mixes simply by requiring the total mass-fraction abundance of the heavy elements, Z, to be the same. However, this result holds only for metallicities significantly less than solar. Above [Fe/H] -0.8, tracks and isochrones for enhanced ?-element mixtures begin to have systematically hotter/bluer turnoffs and red giant branches than those for scaled-solar mixtures of the heavy elements. Also addressed is the extent to which our models satisfy the constraints posed by the local subdwarfs, the distances of which are based on Hipparcos parallax measurements. Our analysis suggests that the predicted metallicity dependence of the location of the lower main sequence on the C-M diagram is in good agreement with the observed dependence. In fact, we do not find any compelling evidence from the local Population II calibrators that the colors of our models require significant adjustments. In further support of our calculations, we find that, both in zero point and slope, the computed giant branches on the (Mbol, log Teff)-plane agree well with those inferred for globular clusters from observations in the infrared. Moreover, our ZAHB models have luminosities that are just outside the 1 ? error bars of the mean MV's inferred for RR Lyrae stars from Baade-Wesselink, statistical parallax, and trigonometric parallax studies. Lower helium contents or higher ?-element abundances or an increase in the conductive opacities are among the possible ways of reducing the differences that remain. To facilitate comparisons with observations, the tracks/ZAHBs are provided with predicted BV(RI)C photometry.

Organogenic Dolomitization in Peritidal to Deep-Sea Sediments

Abstract: Presumed barriers to early dolomitization in normal seawater-derived pore fluids at earth-surface temperatures appear to be overcome within some anoxic, organic-rich sediments as a result of bacterial sulfate reduction and methanogenesis. These processes may promote early dolomitization, particularly during methanogenesis and late stages of sulfate reduction, by concurrently raising and sustaining high pH and high total alkalinity and CO 3 2- concentrations in pore fluids, and by simultaneously either decreasing Mg and Ca hydration or by promoting crystal surface reactions with less hydrated Mg-Ca neutral ion pairs. Volumetrically significant quantities of dolomite are associated with sulfate reduction and/or methanogenesis within peritidal, shallow-marine, and deep-sea deposits. Average concentrations of organogenic dolomite are as much as 70% in some Holocene peritidal deposits, and 28% in Mesozoic to Quaternary deep-sea sediments. Organogenic dolomites are mainly cements, and contain relatively low concentrations of Sr and Mn. Sulfate-reduction dolomites generally are Fe-deficient because of concurrent pyrite precipitation, whereas methanogenetic dolomites may be somewhat more ferroan as Fe substitutes for depleting Mg. Sources of Mg and Ca for dolomite are diffusion from overlying seawater and/or dissolution of precursor carbonate sediments. Dolomites are characterized by a wide range in δ 13 C values wherein those of sulfate reduction versus methanogenetic origin typically are 13 C-depleted and 13 C-enriched, respectively. The extent of 13 C depletion or enrichment, however, depends on the extent of organodiagenetic reactions and amount of 13 C contributed by seawater diffusion, and commonly results in overlap of δ 13 C dolomite values. The range of δ 18 O dolomite values is somewhat more restricted, and generally reflects differences in pore-fluid temperature and salinity. Some of the unresolved issues in organogenic dolomitization are: the relative efficiencies of sulfate reduction versus methanogenesis in promoting dolomitization, depths of dolomite formation inferred on the basis of δ 18 O dolomite values and probable sources of Mg and Ca, and the mode of dolomitization with progressive burial into methanogenetic zones.

Do Politics Perceptions Relate to Political Behaviors? Tests of an Implicit Assumption and Expanded Model

Abstract: This study examined perceived political behaviors as a critical, yet largely overlooked, component in the traditional organizational politics perceptions model Further, this study developed an expanded version of the traditional antecedents to politics perceptions and examined the mediating effect of perceptions of politics in the model Results from 260 full-time employees suggested that the use of reactive/defensive political behaviors exacerbated the already negative effects of perceived organizational politics on outcomes Further, the set of variables that come from the job/work environment were found to explain more variance in perceptions of organizational politics than the set of organizational or individual variables Finally, perceptions of politics demonstrated mediation effects between the antecedent variables and job satisfaction, job anxiety, and intent to turnover Discussion centers around the expanded model and the need to conceptually and empirically link politics perceptions with politi

Valuing Families: Social Work Practice with Families from a Strengths Perspective

Abstract: Social work and social workers have long been concerned with families. Historically, most approaches to social work with families have focused on individual pathology and problem solving or have considered problems of a family member to be symptoms of family dysfunction. In contrast, other approaches to social work have focused on growth, function, and healing. This article describes both problem-focused and growth-focused approaches to practice and presents a strengths approach to practice that values families and builds resilience. Assumptions of the strengths approach are discussed and applied to work with families through a case example.

Impact of atrazine on organophosphate insecticide toxicity.

Abstract: Acute toxicity of selected organophosphorus insecticides (OPs; chlorpyrifos, methyl parathion, diazinon, and malathion) was determined for individual OPs and binary combinations of the OPs with atrazine to larvae of the midge Chironomus tentans. Atrazine individually was not acutely toxic even at high concentrations (10,000 mg/L); however, the presence of atrazine at much lower concentrations (40-200 mg/L) increased the toxicity of chlorpyrifos, methyl parathion, and diazinon. Atrazine did not increase the toxicity of malathion. Possible mechanisms for the synergistic toxicity found between atrazine and chlorpyrifos were investigated, including increased uptake rate and increased biotransformation into a more toxic metabolite. Although the uptake rate was increased by more than 40%, the resulting increase in toxicity would be minimal as compared to the 400% decrease estimated to occur in EC50 values for the same atrazine exposure (200 mg/L). Body residue analysis of midges exposed in vivo to atrazine and chlorpyrifos mixtures for 96 h indicated that a larger amount of metabolites was generated in atrazine treatments as compared to controls. Additionally, in vitro assays of microsomal proteins obtained from treated and control midges indicated that an increase in toxic metabolite (chlorpyrifos-O-analog) was generated in atrazine-treated midges. Therefore, the increase in toxicity is thought to be due to an increase in biotransformation rates of the OPs, resulting in more O-analog within the organism. Keywords—Atrazine Organophosphate insecticides Mixtures Synergism Biotransformation

β-Hydroxy-β-Methylbutyrate (HMB) Supplementation in Humans Is Safe and May Decrease Cardiovascular Risk Factors

Abstract: The leucine metabolite, beta-hydroxy-beta-methylbutyrate (HMB) enhances the effects of exercise on muscle size and strength. Although several reports in animals and humans indicate that HMB is safe, quantitative safety data in humans have not been reported definitively. The objective of this work was to summarize safety data collected in nine studies in which humans were fed 3 g HMB/d. The studies were from 3 to 8 wk in duration, included both males and females, young and old, exercising or nonexercising. Organ and tissue function was assessed by blood chemistry and hematology; subtle effects on emotional perception were measured with an emotional profile test (Circumplex), and tolerance of HMB was assessed with a battery of 32 health-related questions. HMB did not adversely affect any surrogate marker of tissue health and function. The Circumplex emotion profile indicated that HMB significantly decreased (improved) one indicator of negative mood (Unactivated Unpleasant Affect category, P < 0.05). No untoward effects of HMB were indicated. Compared with the placebo, HMB supplementation resulted in a net decrease in total cholesterol (5.8%, P < 0.03), a decrease in LDL cholesterol (7.3%, P < 0.01) and a decrease in systolic blood pressure (4.4 mm Hg, P < 0.05). These effects of HMB on surrogate markers of cardiovascular health could result in a decrease in the risk of heart attack and stroke. In conclusion, the objective data collected across nine experiments indicate that HMB can be taken safely as an ergogenic aid for exercise and that objective measures of health and perception of well-being are generally enhanced.

New Iron(II) and Manganese(II) Complexes of Two Ultra-Rigid, Cross-Bridged Tetraazamacrocycles for Catalysis and Biomimicry

Abstract: The high-spin dichloro Mn2+ and Fe2+ complexes of 4,11-dimethyl-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (1) and 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]tetradecane (2) provide durable new compounds of these elements for important fundamental studies and applications. The compounds are especially noteable for their exceptional kinetic stabilities and redox activity. The X-ray crystal structures of all four complexes demonstrate that the ligands enforce a distorted octahedral geometry on the metals with two cis sites occupied by labile chloride ligands. Magnetic measurements reveal that all are high spin with typical magnetic moments. Cyclic voltammetry of the complexes shows reversible redox processes at +0.110 and +0.038 V (versus SHE) for the Fe3+/Fe2+ couples of Fe(1)Cl2 and Fe(2)Cl2, respectively, while the Mn3+/Mn2+ and Mn4+/Mn3+ couples were observed at +0.585 and +1.343 V, and +0.466 and +1.232 V for the complexes Mn(1)Cl2 and Mn(2)Cl2, respectively. Mn2+(1) was found to react with H2O2 and o...

Feedback linearization with neural network augmentation applied to X-33 attitude control

Abstract: In the application of adaptive flight control, significant issues arise due to vehicle input characteristics such as actuator position limits, actuator position rate limits, and linear input dynamics. The concept of modifying a reference model to prevent an adaptation law from "seeing" and adapting-to these system characteristics is introduced. A specific adaptive control method based on this concept, termed Pseudo-Control Hedging, is introduced that accomplishes this for any Model Reference Adaptive Controller that includes approximate feedback linearization. This method enables continued adaptation while the plant input is saturated. Acceptance and flight certification of an online Neural Network adaptive control law for the X33 Reusable Launch Vehicle technology demonstrator is discussed as motivation for this work. Simulation results applying the method to the X-33 are described. Nomenclature

Decreased Progesterone Levels and Progesterone Receptor Antagonists Promote Apoptotic Cell Death in Bovine Luteal Cells

Abstract: We tested the hypothesis that progesterone (P4) acts at a local level to inhibit luteal apoptosis. Initial experiments employed aminoglutethimide, a P450 cholesterol side-chain cleavage inhibitor, to inhibit steroid synthesis. Cultured bovine luteal cells were treated with aminoglutethimide (0.15 mM) 6 P4 (500 ng/ ml) for 48 h. Luteal cells were recovered and snap frozen for isolation and analysis of oligonucleosomal DNA fragmentation or fixed for morphological analysis. Medium was collected for analysis of P4 levels by RIA. Aminoglutethimide inhibited P4 synthesis by . 95% and increased the level of apoptosis as evidenced by 32 P-labeled oligonucleosomal DNA fragmentation (. 40%). P4 supplementation inhibited the onset of apoptosis that was induced by aminoglutethimide. These data were further supported by morphological assessment of apoptotic cells utilizing a Hoechst staining technique and together strongly suggest that P4 has anti-apoptotic capacity. Using reverse transcription-polymerase chain reaction, we were able to isolate a 380-base pair cDNA from the bovine corpus luteum (CL) that was 100% homologous to the progesterone receptor (PR) previously found in bovine oviductal tissue. Furthermore, PR transcripts were present in large and small luteal cells. Immunohistochemistry also revealed that PR protein was present in both large and small luteal cells. To determine whether the anti-apoptotic effect of P4 was regulated at the receptor level, luteal cells were cultured in the presence of PR antagonists, RU-486 and onapristone, for 48 h. Both antagonists caused approximately a 40% increase in 32 Plabeled oligonucleosomal DNA fragmentation. Interestingly, there was no difference (P $ 0.05) in P4 levels after treatment with PR antagonists. These observations support the concept that P4 represses the onset of apoptosis in the CL by a PR-dependent mechanism.

Characterization of fungal biofilms within a municipal water distribution system.

Abstract: Biofilms of a municipal water distribution system were characterized to assess the occurrence of fungi within surface matrixes. Densities of filamentous fungi ranged from 4.0 to 25.2 CFU cm−2, whereas yeast densities ranged from 0 to 8.9 CFU cm−2. Observations by scanning electron microscopy further suggested that spores, not hyphae or vegetative cells, comprised the primary source of viable propagules.

The Contribution of Parental Discipline, Parental Monitoring, and School Risk to Early-Onset Conduct Problems in African American Boys and Girls.

Abstract: The association of parental discipline and monitoring with the early conduct problems of 123 boys and girls was assessed in a highly disadvantaged, African American sample. Prospective analyses indicated that, after earlier conduct problems were controlled for, coercive parent discipline and poor parental monitoring at age 4 1/2 were independent, reliable predictors of age 6 conduct problems for both boys and girls. The association of parental monitoring with later child conduct problems was mediated, in part, by parents' choice of higher risk schools for their children's kindergarten education. The association of family income with child conduct problems was mediated by parental discipline and monitoring. These models are consistent with previous research on older, European American, more advantaged, male samples, which supports the generality of the association of family processes with child conduct problems across child gender, age, and ethnicity.

Understanding Middle Students' Beliefs About Knowledge and Learning Using a Multidimensional Paradigm

Abstract: Recent theory (Schommer, 1990) suggests that personal epistemology is multidimensional The multidimensional epistemology structure with middle school students was tested in this study Over 1,200 students in Grades 7 and 8 completed an epistemological belief questionnaire Prior theory, developed with college students, suggested 4 epistemological belief factors: Ability to Learn, Structure of Knowledge, Speed of Learning, and Stability of Knowledge Confirmatory factor analysis applied to a random half of the sample indicated that a 3-factor model was a good fit to the data That model was replicated with the second half of the data Follow-up regression analyses indicated that the more students believed in gradual learning and incremental ability to learn, the higher GPA they earned

Simulations of quantum neural networks

Abstract: We explore by simulation ways in which an array of quantum dot molecules could serve as a quantum neural computer. First, we show that a single quantum dot molecule evolving in real time can act as a recurrent temporal quantum neural network. Inputs are prepared by fixing the initial states of a quantum dot molecule, and outputs determined by reading its value at a given time T later. The nodes of the network are the instantaneous states of the molecule at successive time slices. The nodes interact indirectly through their mutual interaction with local and phononic modes of the substrate. These modes can be preferentially excited optically, and, therefore, controlled externally. The number of excitations can thus be used as trainable “weight” parameters for a neural network. This network is shown to perform classical logic gates. By preparing the input state as a superposition state, multiple inputs can be encoded as a single initial state. Second, we simulate the possibility of a spatial, rather than temporal, design, as a Hopfield net. The network consists of a regular array of quantum dot molecules on a suitable substrate. The molecules interact indirectly as before, and, now, with each other directly through Coulombic interactions. Both of the quantum networks have none of the “wiring problems” of traditional neural nets: the necessary connections are supplied by the physical system itself. Computation is performed by the intrinsic physics of the physical system. The long range character of the phononic interactions takes the net beyond traditional local connectionist structures. The hypothesized increase in complexity and power, in going to the quantum regime, is demonstrated. We train the quantum Hopfield net using simultaneous recurrent backpropagation.

Structure, physical, and photophysical properties of platinum(II) complexes containing bidentate aromatic and bis(diphenylphosphino)methane as ligands.

Abstract: This study focuses on a series of PtII(L−L‘)(dppm)n+ complexes, where dppm is bis(diphenylphosphino)methane and L−L‘ are C∧C‘ (n = 0), C∧N (n = 1), and N∧N‘ (n = 2) aromatic ligands. Structural characteristics are as follows: for [Pt(phen)(dppm)](PF6)2, a N∧N‘ derivative, monoclinic, C2/c, a = 33.583(6) A, b = 11.399(2) A, c = 22.158(4) A, Z = 8; for [Pt(phq)(dppm)](PF6), a C∧N derivative, triclinic, P1, a = 11.415(3) A, b = 13.450(3) A, c = 14.210(4) A, Z = 2; for [Pt(phpy)(dppm)](PF6), a C∧N derivative, triclinic, P1, a = 10.030(3) A, b = 13.010(2) A, c = 15.066(4) A, Z = 2; and for [Pt(bph)(dppm)], a C∧C‘ derivative, P21/c, a = 17.116(7) A, b = 21.422(6) A, c = 26.528(6) A, Z = 12, where phen is 1,10-phenanthroline, phq is 2-phenylquinoline, phpy is 2-phenylpyridine, and bph is 2,2‘-biphenyl. Structural features indicate that the Pt−C bond distance is shorter than the Pt−N bond distance in symmetrical complexes and that the Pt−P bond distance trans to N is shorter than the Pt−P bond trans to C. This...

Intelligibility/Severity Measurements of Prekindergarten Children's Speech

Abstract: Intelligibility/severity measurements were obtained for 48 prekindergarten children with varying levels of phonological proficiency/ deficiency. The measure used as the “standard” was percentage of words understood (i.e., orthographically transcribed correctly) in continuous speech in a known context by unfamiliar trained listeners. The children were divided into four groups based on the percentage of words understood from their continuous speech samples. The ranges of intelligibility for each group were: (a) 91–100% for children with “adult-like” speech; (b) 83–90% for children in the “mild” category; (c) 68–81% for children with moderate intelligibility/speech involvement; and (d) 16–63% for the 12 children in the “severe” (i.e., least intelligible) category. When the percentages of the children in the severe group were excluded, the range of the top three groups combined was 68–100% and the mean was 85%. For a child 4 years of age or older, any percentage of words understood in connected speech that fa...

The Effect of Labor Pain Relief Medication on Neonatal Suckling and Breastfeeding Duration

Abstract: We examined the relationship of labor pain relief medications with neonatal suckling and breastfeeding duration in 129 mothers delivering vaginally. Suckling was measured using the Infant Breastfeeding Assessment Tool (IBFAT). Controlling for infant age, birthweight, and gender, infants of unmedicated mothers had higher IBFAT suckling scores than those of medicated mothers (x = 11.1 vs. x = 8.2 respectively, P = .001). IBFAT suckling scores for intravenous and epidural groups were similar (x = 8.5) while those who received a combination of both intravenous and epidural medications were lower (x = 6.4 +/- 2.96, P = .001). Mothers evaluated their breastfeeding similarly to nurse evaluators (Z = 9.39, P = .001). Breastfeeding duration did not differ between unmedicated and medicated groups; however, dyads with low IBFAT scores weaned earlier than those with medium or high scores. Labor pain relief medications diminish early suckling but are not associated with duration of breastfeeding through 6 weeks postpartum.

Gender differences in homework and test scores in Mathematics, Reading and Science at tenth and twelfth grade

Abstract: Gender differences in maths, reading, science and the amount of homework done out of school were obtained for tenth and twelfth graders from the American National Educational Longitudinal Study. Males obtained significantly higher mean scores in maths and science, and females obtained significantly higher mean scores in reading and amount of homework. There were significant correlations between test scores and amount of homework, suggesting that amount of homework contributes to test scores.

A Deductive Database Approach to Automated Geometry Theorem Proving and Discovering

Abstract: We report our effort to build a geometry deductive database, which can be used to find the i>fixpoint for a geometric configuration. The system can find all the properties of the configuration that can be deduced using a fixed set of geometric rules. To control the size of the database, we propose the idea of a i>structured deductive database. Our experiments show that this technique could reduce the size of the database by one hundred times. We propose the data-based search strategy to improve the efficiency of forward chaining. We also make clear progress in the problems of how to select good geometric rules, how to add auxiliary points, and how to construct numerical diagrams as models automatically. The program is tested with 160 nontrivial geometry configurations. For these geometric configurations, the program not only finds most of their well-known properties but also often gives unexpected results, some of which are possibly new. Also, the proofs generated by the program are generally short and totally geometric.

A Topography of Self-Help Groups: An Empirical Analysis

Abstract: The current managed health care system creates an environment in which social workers need to be knowledgeable about low-cost interventions. Self-help groups have the potential to be beneficial to social workers' clients. Surprisingly, little is known about the characteristics and activities of many groups and the extent to which groups receive guidance and support from professionals and established national and local organizations. Whereas many social workers are aware of Alcoholics Anonymous (AA), there are thousands of other types of groups that could be helpful to their clients. This study examines the member and group characteristics, professional involvement, and local and national affiliations of 253 self-help groups. Results suggested that many groups have shared leadership, recruit group members, receive assistance from professionals, and receive guidance from national and local organizations. Results are discussed in terms of how social workers can assist and use self-help groups in the current managed health care system.

A Fundamental Analysis Approach to Oil and Gas Firm Valuation

Abstract: Most fundamental analysis studies have focused on fundamentals selected by a data-driven approach on large samples of firms from numerous industries. This paper reports the results of a fundamental analysis of a single industry, the US oil and gas exploration and production industry, using variables identified by industry financial analysts. The results demonstrate a significant relationship between a number of the fundamentals with both the market value of equity and cumulative stock return. The results also suggest that the fundamentals provide incremental information beyond earnings, change in earnings, and book value of equity when explaining equity values and stock returns.

Machining as a Wedge Indentation

Abstract: A case is made for the consideration of single-point machining of ductile metals as a special type of wedge indentation process. A general-purpose finite element analysis of machining using iterative rezoning is developed based on this analogy. The accuracy of this analysis, which does not incorporate any separation criterion, is limited only by our knowledge of the material properties and the friction conditions at the tool-chip interface. Strain hardening, strain rate effects, and the temperature dependence of the properties of the work material can be taken into consideration. While Coulomb friction is assumed at the chip-tool interface in the present model, it can easily be reformulated to include more complicated frictional interactions such as adhesion. An analysis of the cutting/ indentation of an isotropic work-hardening material at slow speeds under two different friction conditions is presented. It is shown that many of the important features of machining processes are consistently reproduced by the analysis.

Joint Clearances With Lubricated Long Bearings in Multibody Mechanical Systems

Abstract: Proper modeling of joint clearance is of great importance in the analysis and design of multibody mechanical systems. The clearance may be due to wear or imperfection in manufacturing. When there is no lubricant in the clearance solid-to-solid contact occurs. The impulse due to contact between the links is transmitted throughout the system. The presence of a lubricant avoids such contact, as the hydrodynamic forces developed by the lubricant film support the loads acting on the bodies and prevent the bodies from coming into contact. In this paper, an analysis of revolute joint clearances in multibody mechanical systems with and without lubricant is presented. Squeeze as well as viscous effects are considered utilizing the hydrodynamic theory of lubrication in long bearings. Unlike the traditional machine design approach, the instantaneous lubricant forces are the unknown and evaluated in terms of the known geometrical position and velocity of the journal and bearing. In the case of analysis of a joint clearance with no lubricant, a modified Hertzian relation is used to model the impact or contact between the journal and bearing, which includes a hysteresis damping term to account for the energy dissipation during impact. The methodology is applied for the analysis of a slider-crank mechanism having a clearance in the piston pin. The simulations are carried out with and without lubricant and the results are compared, It is shown that the lubricant results in a steady motion with fewer peaks in the required cranking moment for the system.

Range of motion of the wrist: implications for designing computer input devices for the elderly

Abstract: Purpose : The purpose of this study was to report normative values of the amplitude of joint wrist motions and grip strength for older age groups. Method : Volunteers, (N = 147) were divided into four age groups, 60-69, 70-79, 80-89 and 90+ years, with a total of 62 men and 85 women. Maximum range motion values were obtained for wrist flexion, extension and ulnar deviation. In addition, grip strength measures were obtained for each participant. Results : In general, the strength and ROM values for the oldest participants in this study were lower than those of the younger age group (age 60 to 69) and significantly lower than those published for subjects between 25 and 54 years of age. Furthermore, across all age groups males were significantly stronger than females. However, females tended to have greater ROM than males, particularly for wrist extension and ulnar deviations. Joint ROM and grip strength declined significantly with age for both males and females. Comparisons with published data for younger s...