Contact Dimensions Research Articles

The Contact Hypothesis and Attitudes Toward Latinos in the United States

ObjectivesAlthough the contact hypothesis occupies an important place in the study of intergroup relations, several important questions remain understudied. We contribute to the literature by examining the associations between multiple aspects of contact with Latinos and several types of attitudes toward U.S. Latinos, including attitudes toward immigration restrictions.MethodsWe use OLS and logistic regression techniques to analyze the opinions of Anglo (non‐Hispanic white) and African‐American respondents from the 2000 NORC General Social Survey (GSS), which contained a special module on attitudes regarding ethnicity and diversity issues.ResultsOur findings reveal a clear association between close nonkin Latino ties, that is, friendship, and more favorable or empathetic attitudes toward Latinos as well as less restrictive or punitive views concerning immigration policy. Having Latino relatives is also linked with several of these attitudes. Most other dimensions of contact (e.g., attending high schools with significant Latino populations, having Latino acquaintances, Spanish‐language fluency, and residing in areas with relatively high Latino populations) have at least some association with the attitudes under study, although for most of these contact measures the significance of the effects is inconsistent across outcomes.ConclusionsThe findings reinforce the significance of intergroup friendships and underscore the importance of understanding their social origins, patterning, and consequences for diverse groups. It is also important to probe the differential effects of specific types and arenas of intergroup contact on specific attitudinal and policy outcomes.

Alien Worlds: Social and Religious Dimensions of Extraterrestrial Contact

Alien Worlds: Social and Religious Dimensions of Extraterrestrial Contact

Assessment of the applicability of the Hertzian contact theory to edge-loaded prosthetic hip bearings

The components of prosthetic hip bearings may experience in-vivo subluxation and edge loading on the acetabular socket as a result of joint laxity, causing abnormally high, damaging contact stresses. In this research, edge-loaded contact of prosthetic hips is examined analytically and experimentally in the most commonly used categories of material pairs. In edge-loaded ceramic-on-ceramic hips, the Hertzian contact theory yields accurate (conservatively, <10% error) predictions of the contact dimensions. Moreover, the Hertzian theory successfully captures slope and curvature trends in the dependence of contact patch geometry on the applied load. In an edge-loaded ceramic-on-metal pair, a similar degree of accuracy is observed in the contact patch length; however, the contact width is less accurately predicted due to the onset of subsurface plasticity, which is predicted for loads >400 N. The Hertzian contact theory is shown to be ill-suited to edge-loaded ceramic-on-polyethylene pairs due to polyethylene's nonlinear material behavior. This work elucidates the methods and the accuracy of applying classical contact theory to edge-loaded hip bearings. The results help to define the applicability of the Hertzian theory to the design of new components and materials to better resist severe edge loading contact stresses.

Probing material properties with sharp indenters: a retrospective

A retrospective on the use of sharp, fixed-profile indenters as materials probes is presented. Indentation is proposed as a simple but powerful methodology for evaluating basic mechanical properties—elastic modulus, hardness, toughness—in all classes of materials. Indentation also provides unique insight into fundamental deformation and fracture processes. Of particular interest is the existence of intrinsic size effects as characteristic contact dimensions pass from macro- to micro- to nano-scale dimensions. The utility of indentations as ‘controlled flaws’ in the context of strength of materials is outlined. The roles of two other important material factors—rate effects and microstructure—are considered. Examples of technological and biological applications are presented as illustrations of the widespread power of the technique. Strengths and limitations of the methodology as a routine testing protocol are discussed.

Effects of Nanoscale Contacts to Graphene

Understanding and optimizing transport between metal contacts and graphene is one of the foremost challenges for graphene devices. In this letter, we present the first results on the effects of reducing contact dimensions to the nanoscale in single-layer graphene transistors. Using noninvasive voltage probes to the graphene channel, the contact resistance was extracted and observed to increase dramatically at contact lengths below 200 nm. Also affected was the extrinsic transconductance, reducing by more than 70% when scaling the contacts from 200 to 50 nm. No significant change in performance per unit width was observed when reducing the contact/device width from 500 to 80 nm. These results provide key insights into the ultimate scalability of graphene transistors, particularly when considering them for a densely integrated technology.

A Cross-cultural Analysis of Online Satisfaction, Service Failure and Recovery: An E-A-S-QUAL Approach

The purposes of the study were to identify the online service attributes that contribute to online consumer experiences of satisfaction, service failure, and service recovery and to examine whether differences exist in these attributes between U.S. and Korea. E-A-S-QUAL provided a useful framework for the study. Focus group interviews and web surveys were conducted by utilizing college students in both countries. No significant cultural differences were found in online service dimensions of service satisfaction. Personalization was the most frequently mentioned online service dimension of service satisfaction both in the U.S. and Korea. The findings showed significant cultural differences in terms of online service dimensions responsible for service failure and recovery. For Korean consumers, merchandising was one of the key online service dimensions of service failure, while efficiency was the important service dimension resulting in service failure for the U.S. consumers. In addition, for U.S. consumers, efficiency and personalization were the two most frequently mentioned service dimension for service recovery, while Korean consumers put more importance on the contact and information dimensions for service recovery. This study provided a comprehensive list of online service attributes important to online apparel retailing.

Properties of a short questionnaire for assessing primary care experiences for children in a population survey.

BackgroundThe Primary Care Assessment Tool (PCAT) is an interesting set of tools for primary care research. A very short version could inform policy makers about consumer experiences with primary care (PC) through health surveys. This work aimed to investigate the validity and reliability of a selection of items from the child short edition (CS) of the PCAT.MethodsA 24 item questionnaire permitted the identification of a regular source of care and the assessment of the key attributes of first contact, ongoing care over time, coordination, services available and services received (comprehensiveness), and cultural competence. Structural validity, reliability, and construct validity were assessed using responses from 2,200 parents of a representative sample of the population aged 0 to 14 years in Catalonia (Spain) who participated in the 2006 Health Survey. Structural validity was analyzed using exploratory and confirmatory factor analyses and reliability was assessed using Cronbach's alpha. Construct validity was assessed using linear regression analysis between PC experience scores and a measure of overall user satisfaction with healthcare services.ResultsA total of 2,095 (95.2%) parents provided useable responses on PC. After Confirmatory Factor Analysis (CFA), the best fitting model was a 5-factor model in which the original dimensions of first contact and ongoing care were collapsed into one. The CFA also showed a second order factor onto which all domains except services available loaded (root mean square error of approximation = 0.000; comparative fit index = 1.00). Cronbach's alpha values for one of the original scales (first-contact) was poor (alpha < 0.50), but improved using the modified factor structure (alpha > 0.70). Scores on the scales were correlated with satisfaction with healthcare services (p < 0.01), thereby providing some preliminary evidence of construct validity.ConclusionsThis very short questionnaire obtained from the PCAT-CE yields information about five attributes of PC and a summary score. It has shown evidence of validity and reliability for judgments about experiences with primary care overall. If space on surveys is at a premium, the instrument could be useful as a measure of PC experiences.

Three-Dimensional Electromagnetic and Electrical Simulation of HgCdTe Pixel Arrays

We have investigated the combined electromagnetic and electrical response of HgCdTe-based pixel detector arrays with different geometries. We have computed the propagation of the optical signal in the detector structure by solving Maxwell’s curl equations using a finite-difference time-domain approach. From the field distribution inside the device, we have evaluated the optical carrier generation rate. Using this information in a three-dimensional (3D) numerical model based on a drift–diffusion approach, we have computed the quantum efficiency and photoresponse of a number of pixel geometries. Specifically, we have analyzed the response of both mesa-type and planar detector arrays with and without CdZnTe substrate. Furthermore, the electromagnetic response has also been evaluated for different metal contact dimensions and configurations. It is found that, for mesa-type arrays without the substrate, significant reflection effects take place in the device that lead to resonance peaks in the photoresponse.

Phase change random access memory featuring silicide metal contact and high-κ interlayer for operation power reduction

A phase change memory device integrated with a nickel monosilicide (NiSi) bottom electrode and a dielectric (Ta2O5) interlayer was investigated. The presence of a low thermal conductivity thin film between the bottom electrode and phase change layer promotes heating efficiency in the device. Reset voltages down to 2.2 and 1.86 V could be achieved for memory device without and with the Ta2O5 interlayer, respectively. In addition, low reset current of 0.66 mA and SET current of 0.2 mA were obtained for devices with Ta2O5 interlayer having a contact dimension of ∼1 μm. Endurance of the devices was also studied.

Phase Change Random Access Memory Devices with Nickel Silicide and Platinum Silicide Electrode Contacts for Integration with CMOS Technology

Phase change random access memory (PCRAM) cells utilizing nickel monosilicide (NiSi) or platinum monosilicide (PtSi) as the bottom electrode as well as a heater material was demonstrated. Electrical and simulation results demonstrate the feasibility of employing silicides as a bottom electrode/heater in a PCRAM. The memory cells fabricated attained promising results such as low programming currents and sufficient resistance ratio between the crystalline (SET) and amorphous (RESET) states. A low RESET current of and a SET current of were obtained for contact dimensions of , while a resistance ratio of 2 orders of magnitude could be achieved employing PtSi as the bottom electrode. This work therefore enables the integration of PCRAM directly on the silicided drain regions of field effect transistors, facilitating compact integration in complementary metal-oxide-semiconductor (CMOS) technology with reduced process complexity and cost.

Effect of implant drill characteristics on heat generation in osteotomy sites: a pilot study

The objective of this study was to evaluate the effect of drill-bone contact area on bone temperature during osteotomy preparation. Conventional triflute Ø3.6 mm drills were modified with the intent to reduce frictional heat induction. The peripheral dimensions of the drill were reduced 0.15, 0.35 and 0.5 mm to evaluate the effect of surface area on induction of frictional heat between the drill and bone/cutting debris (parameter A). Also, the lateral cutting surface of the drill was set to 0.1, 2 and 7.5 mm to estimate heat induced by direct function of the drill (parameter B). A non-modified triflute drill (parameter A: 0 mm; parameter B: 15 mm) served as control. Thus, nine drills with different A/B combinations vs. one control were tested in artificial bone. Real-time temperature changes (during drilling and withdrawing) were assessed using an infrared thermal imager. Each drilling procedure was performed up to 20 times. Thermal image data were transferred to a PC for simultaneous analysis. Mean temperature changes for all modified drill combinations were smaller than for the control (P<0.001). The effects of parameters A and B were statistically significant (P<0.001). There was a significant interaction effect between the two parameters (P<0.001) showing that the effect of parameter A on the mean temperature changes is different depending on the values of parameter B. As the dimensions of parameter B decreased, the temperature change during drilling also decreased. However, a tendency for the temperature to increase or decrease by parameter A was not observed. Within the limitations of this pilot study, the observations herein suggest that reduction in contact area between the drill and bone reduces heat induction. Further studies to optimize drill/bone contact dimensions are needed.

Deformation and friction of MoS 2 particles in liquid suspensions used to lubricate sliding contact

Tribology of a well known solid lubricant molybdenum disulphide is studied here in water and oil medium, over a large range of contact dimensions. Lateral force microscopy is used to identify the deformation modes; intra-crystalline slip, plastic grooving, fragmentation and fracture, of single particles. The medium and agglomeration were found to dictate the deformation mode. Steel on steel tribology lubricated by suspensions of these particles in liquid media was conducted over a range of contact pressure and sliding velocity. A scrutiny of the frictional data with the aid of Raman spectroscopy to identify the transfer film, suggested that the particle size, as it is at contact, is an important tribological parameter. Ultrasonication of the suspension and dispersion of the particle by surfactants were used to control the apriori particle size fed into the suspension. Correspondence of friction data of the gently sonicated suspension with that of the ultrasonicated suspension with dispersants indicated the importance of liquid ingestion by these particles as it controls their mode of deformation and consequent tribology.

Sensitivity of Bragg gratings in birefringent optical fiber to transverse compression between conforming materials

A theoretical and experimental investigation of the transverse load sensitivity of Bragg gratings in birefringent fibers to conforming contact is presented. A plane elasticity model is used to predict the contact dimensions between a conforming material and optical fiber and the principal stresses, indicating birefringence, created as a result of this contact. The transverse load sensitivity of commercially available birefringent fiber is experimentally measured for two cases of conforming contact. Theoretical and experimental results show that birefringent optical fiber can be used to make modulus-independent measurements of contact load. Therefore, Bragg gratings could be applied to conforming contact load measurements while avoiding some of the complications associated with existing contact sensors: specifically, the necessity to precalibrate by using materials with mechanical properties identical to those found in situ.

Assessment of Elliptical Conformal Hertz Analysis Applied to Constant Velocity Joints

To analyze the contact between two spherical bodies with different radii of curvature, the three-dimensional (3D) Hertz theory for elliptical contact is typically used. When the two contacting bodies have high conformity, such as the case for ball-in-groove, the Hertz theory may break down. In this research, finite element analysis (FEA) was used to assess the validity of 3D Hertz theory as found in the roller-housing contact of constant velocity joints. The contact area, normal approach, and contact pressure results show that Hertz agrees with FEA predictions for low compressive loads, where the contact ellipse is within the geometrical contact dimensions. At higher loads the contact ellipse extends beyond the contacting geometrical dimensions and the simplified analytical Hertz results diverge from the FEA results.

Solution to Hertzian Contact Problem between Wheel and Rail for Small Radius of Curvature

There have been several attempts to solve Hertz equation for curved surface contact problem. One application of Hertzian contact problem is to determine the contact properties between wheel and rail. It is important to understand the contact between wheel and rail so that excessive wear can be avoided and train accidents can be minimized. In this work, an attempt has been made to solve Hertzian contact for small radius of curvature using a simple newly invented formula. A finite element modeling was also performed to observe the variations of maximum contact stress in rail with respect to the change rail radius of curvature. The invented formula was to modify the formula of Fischer et.al especially for the major and minor axis so that a more accurate result was obtained in determining the contact dimensions and maximum contact pressure.

Acculturation, discrimination, and adaptation among second generation immigrant youth in Montreal and Paris

Research with immigrant youth has shown that they have a variety of orientations to their acculturation process. These different paths (“acculturation strategies”) have been described in terms of assimilation, integration, marginalisation and separation (AIMS). This research has also shown that there are variable adaptations or outcomes to acculturation. Of greatest importance is the finding that these variations in adaptation are usually related to the acculturation strategies that youth use. Generally, those who involve themselves in both their heritage culture and that of the national society (by way of integration) have the most positive psychological well-being, and are most adjusted in school and in the community; in contrast, those who are minimally involved with either culture (the marginalisation course), are least well-adapted; and those who are primarily oriented towards one or the other culture (assimilation or separation) generally fall in between these two adaptation poles. The present study examines the generality of this pattern by comparing samples from two societies that have very different policies and practices with respect immigration and acculturation: Canada and France. We measured acculturation attitudes, identity and behaviours along the two basic dimensions of cultural maintenance and social contact, and then cross-tabulated them, creating the four acculturation orientations. In both societies the usual pattern is replicated: youth who prefer integration have higher self-esteem scores than those who are marginalised; youth preferring assimilation and separation fall in between. This pattern was stronger in Canada than in France, a finding that is interpreted in terms of the differential social context faced by youth in the two societies, particularly the differing national policies and youths’ experience of discrimination.

Structure of Circulation Flows in Polymer Solution Droplets Receding on Flat Surfaces

In a previous report where internal flows were experimentally visualized in polymer solution droplets receding on a lyophobic surface [Kaneda et al., Langmuir 2008, 24, 9102-9109], the direction of the circulation flow was found to depend on solvent and solute concentration. To identify the reason for this finding, the internal flow in the droplet is investigated numerically. A mathematical model predicts that double circulation flows initiate after a single flow develops at high Marangoni numbers, while only a single circulation flow develops at low Marangoni numbers. The dependencies of the calculated velocities on the solvent and the initial solute concentration agree qualitatively with experiment. It is concluded that the difference of the flow directions that were investigated experimentally is due to such a change in the flow structures. The effects of the contact angle and dimensions on transport phenomena in a droplet are also discussed.

“V”ictory Transosseous Equivalent Suture Configuration for Arthroscopic Rotator Cuff Tear Repairs of Iatrogenically Completed PASTA Lesions and Full-Thickness “U”-shaped Tears

The cost of numerous anchors in rotator cuff surgery is high from both an economic standpoint as well as a physiologic one. More anchors means increased cost and increased surgical time; additionally, the greater number of anchors placed, the greater the expense on the native bone that they inevitably replace. It is therefore in the surgeon's and patient's best interest to use the appropriate number of anchors, no more and no less, with the appropriate number being that which allows for strong, stable fixation with minimal gap formation and maximal healing potential and recovery. The transosseous equivalent repair technique described herein uses a single double-loaded bioabsorbable suture anchor placed along the medial border of the rotator cuff foot print and the humeral head articular cartilage margin followed by 1 pushlock (Arthrex, Naples, Florida) anchor placed laterally on the vertical aspect of the greater tuberosity. It is designed for small to medium "U"-shaped tears and for iatrogenically completed partial articular supraspinatus tendon avulsions of moderate to large size, the so-called PASTA lesion. The use of selective knot placement allows for the conversion of a linear construct into a "V" configuration, optimizing repair strength and allowing for earlier rehabilitation while maximizing the healing biology seen with increased footprint contact dimensions and less repair gap formation.

A New Three-Dimensional Capacitor Model for Accurate Simulation of Parasitic Capacitances in Nanoscale MOSFETs

A new 3-D gate capacitor model is developed to accurately calculate the parasitic capacitances of nanoscale CMOS devices. The dependences on gate length and width, gate electrode and dielectric thicknesses, gate-to-contact spacing, and contact dimension and geometry are fully incorporated in this model. The accuracy is certified by an excellent match with the 3-D interconnection simulation results for three structures with strip, square, and circular contacts. The features of being free from fitting parameters and proven accuracy over various geometries make this model useful for nanoscale MOSFET parasitic capacitance simulation and analysis. Furthermore, the developed capacitor model in the form of multidimensional integral can easily be deployed in general circuit simulators. This model predicts that the parasitic capacitance <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">of</sub> dominates around 25% of the intrinsic gate capacitance ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gint</sub> ) in 80-nm MOSFETs and that the near nonscalability with gate length brings the weighting factor <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">of</sub> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gint</sub> above 30%/40%/60% in 65-/45-/32-nm devices. It actually exceeds the limitation defined by the most updated ITRS and reveals itself as a show-stopper in high-speed and high-frequency circuit design.

Threshold and Filament Current Densities in Chalcogenide-Based Switches and Phase-Change-Memory Devices

Threshold current density of switching was found to grow several decades at constant threshold electric field with reducing interelectrode distance. Data are compared with predictions of various switching theories. Experimental estimate of current density in an electronic filament is reported based on a programming "dead-space" observation in a ring contact device with one subcritical bottom contact dimension. Significance of the shape of S-type negative differential conductivity curve and, namely, the slope of the second part with positive differential conductivity for the programming of phase-change memory is discussed.