Science.gov

Sample records for actual contact area

  1. Electrical resistance determination of actual contact area of cold welded metal joints

    NASA Technical Reports Server (NTRS)

    Hordon, M. J.

    1970-01-01

    Method measures the area of the bonded zone of a compression weld by observing the electrical resistance of the weld zone while the load changes from full compression until the joint ruptures under tension. The ratio of bonding force to maximum tensile load varies considerably.

  2. The Frictional Force with Respect to the Actual Contact Surface

    NASA Technical Reports Server (NTRS)

    Holm, Ragnar

    1944-01-01

    Hardy's statement that the frictional force is largely adhesion, and to a lesser extent, deformation energy is proved by a simple experiment. The actual contact surface of sliding contacts and hence the friction per unit of contact surface was determined in several cases. It was found for contacts in normal atmosphere to be about one-third t-one-half as high as the macroscopic tearing strength of the softest contact link, while contacts annealed in vacuum and then tested, disclosed frictional forces which are greater than the macroscopic strength.

  3. Reducing contact resistance in graphene devices through contact area patterning.

    PubMed

    Smith, Joshua T; Franklin, Aaron D; Farmer, Damon B; Dimitrakopoulos, Christos D

    2013-04-23

    Performance of graphene electronics is limited by contact resistance associated with the metal-graphene (M-G) interface, where unique transport challenges arise as carriers are injected from a 3D metal into a 2D-graphene sheet. In this work, enhanced carrier injection is experimentally achieved in graphene devices by forming cuts in the graphene within the contact regions. These cuts are oriented normal to the channel and facilitate bonding between the contact metal and carbon atoms at the graphene cut edges, reproducibly maximizing "edge-contacted" injection. Despite the reduction in M-G contact area caused by these cuts, we find that a 32% reduction in contact resistance results in Cu-contacted, two-terminal devices, while a 22% reduction is achieved for top-gated graphene transistors with Pd contacts as compared to conventionally fabricated devices. The crucial role of contact annealing to facilitate this improvement is also elucidated. This simple approach provides a reliable and reproducible means of lowering contact resistance in graphene devices to bolster performance. Importantly, this enhancement requires no additional processing steps. PMID:23473291

  4. The contact area dependent interfacial thermal conductance

    SciTech Connect

    Liu, Chenhan; Wei, Zhiyong; Bi, Kedong; Yang, Juekuan; Chen, Yunfei; Wang, Jian

    2015-12-15

    The effects of the contact area on the interfacial thermal conductance σ are investigated using the atomic Green’s function method. Different from the prediction of the heat diffusion transport model, we obtain an interesting result that the interfacial thermal conductance per unit area Λ is positively dependent on the contact area as the area varies from a few atoms to several square nanometers. Through calculating the phonon transmission function, it is uncovered that the phonon transmission per unit area increases with the increased contact area. This is attributed to that each atom has more neighboring atoms in the counterpart of the interface with the increased contact area, which provides more channels for phonon transport.

  5. Molecular dynamics study of contact mechanics: contact area and interfacial separation from small to full contact

    NASA Astrophysics Data System (ADS)

    Yang, Chunyan; Persson, Bo

    2008-03-01

    We report a molecular dynamics study of the contact between a rigid solid with a randomly rough surface and an elastic block with a flat surface. We study the contact area and the interfacial separation from small contact (low load) to full contact (high load). For small load the contact area varies linearly with the load and the interfacial separation depends logarithmically on the load [1-4]. For high load the contact area approaches to the nominal contact area (i.e., complete contact), and the interfacial separation approaches to zero. The present results may be very important for soft solids, e.g., rubber, or for very smooth surfaces, where complete contact can be reached at moderate high loads without plastic deformation of the solids. References: [1] C. Yang and B.N.J. Persson, arXiv:0710.0276, (to appear in Phys. Rev. Lett.) [2] B.N.J. Persson, Phys. Rev. Lett. 99, 125502 (2007) [3] L. Pei, S. Hyun, J.F. Molinari and M.O. Robbins, J. Mech. Phys. Sol. 53, 2385 (2005) [4] M. Benz, K.J. Rosenberg, E.J. Kramer and J.N. Israelachvili, J. Phy. Chem. B.110, 11884 (2006)

  6. Calibration of contact areas: the influence of corner rounding

    NASA Astrophysics Data System (ADS)

    Richter, Jan; Zerbe, Eva-Maria; Marschner, Thomas

    2007-10-01

    The precise reporting of critical dimension (CD) features on photolithographic masks is an essential part of the mask production process. A wide range of external (standardization by national institutes) and internal (standardization within mask houses to match different tools) methods has been set up to ensure calibration consistency for the simple one dimensional case. One of the current developments is to expand these concepts to area measurements. This is to achieve better reproducibility of CD tools and to achieve a better characterization of contacts with respect to their imaging behaviour in wafer scanners. Here, we report some very fundamental constrains of this approach that have to be taken into account regardless of the actual measurement strategy. The major result is that for two dimensional contacts the shape has to be considered. This is due to the fact that the usually constant offset for calibration of critical dimensions in one dimension is no longer a constant but depends on the absolute size of the contact and the value of the corner rounding. For standard values of 200 nm contacts with corner rounding of 75 nm and calibration offsets around 20 nm maximum systematic differences of about 2nm will be obtained. Given the fact that even 40 nm calibration differences for photomask standards can be observed even for national institutes, these systematic errors can be easily as large as 6 nm for 200 nm structures. This systematic error clearly exceeds the road map targets for critical dimension off-target specifications for the coming technology node. This statement is even emphasized by the fact that in future contact layer specifications will be smaller than for lines/space layers. Once tool independent characterization of contact areas has to be achieved, area measurement in each mask house needs a second thought to implement these systematic constrains. Here, we show that the additional measurement of the corner rounding ís a relatively easy method

  7. Effect of time derivative of contact area on dynamic friction

    NASA Astrophysics Data System (ADS)

    Arakawa, Kazuo

    2014-06-01

    This study investigated dynamic friction during oblique impact of a golf ball by evaluating the ball's angular velocity, contact force, and the contact area between the ball and target. The effect of the contact area on the angular velocities was evaluated, and the results indicated that the contact area plays an important role in dynamic friction. In this study, the dynamic friction force F was given by F = μN + μη dA/dt, where μ is the coefficient of friction, N is the contact force, dA/dt is the time derivative of the contact area A, and η is a coefficient associated with the contact area.

  8. The steady-state tangential contact problem for a falling drop type of contact area on corrugated rail by simplified theory of rolling contact

    NASA Astrophysics Data System (ADS)

    Piotrowski, Jerzy

    1991-10-01

    Investigation of contact mechanical nonlinearities of a mathematical model of corrugation revealed that the typical shape of contact patch resembles a falling drop of water. A contact patch of that shape was approximated with a figure composed of two parts of ellipses with different eccentricities. The contact pressure distribution was assumed as a smoothing ensemble of two paraboloidal distributions. The description of a general case of double half elliptical contact area was given but a special case of double half elliptical contact is more interesting as it possesses some Hertzian properties. It was shown how three geometrical parameters of double half elliptical contact can be chosen when actual, non-Hertzian contact is known. A linear theory was written which indicates that the lateral vibrations of the rail may be excited only due to shape variation on corrugation even if any other cause for these vibrations does not exist. For nonlinear theory a computer program, based on FASTSIM algorithm by Kalker, was written. The aim is to calculate the creep forces and frictional power density distribution over the contact area. Also, a graphic program visualizing the solution was written. Numerical results are not provided; unattended and unsolved problems relevant for this type of contact are listed.

  9. Bifocal contact lenses: History, types, characteristics, and actual state and problems

    PubMed Central

    Toshida, Hiroshi; Takahashi, Kozo; Sado, Kazushige; Kanai, Atsushi; Murakami, Akira

    2008-01-01

    Since people who wear contact lenses (CL) often continue using CL even when they develop presbyopia, there are growing expectations for bifocal CL. To understand actual state and problems, history, types, and their characteristics are summarized in this review. Bifocal CL have a long history over 70 years. Recently, bifocal CL have achieved remarkable progress. However, there still is an impression that prescription of bifocal CL is not easy. It should also be remembered that bifocal CL have limits, including limited addition for near vision, as well as the effects of aging and eye diseases in the aged, such as dry eye, astigmatism, cataract, etc. Analysis of the long-term users of bifocal CL among our patients has revealed the disappearance of bifocal CL that achieved unsatisfactory vision and poor contrast compared with those provided by other types of CL. Changing the prescription up to 3 times for lenses of the same brand may be appropriate. Lenses that provide poor contrast sensitivity, suffer from glare, or give unsatisfactory vision have been weeded out. The repeated replacement of products due to the emergence of improved or new products will be guessed. PMID:19668441

  10. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    SciTech Connect

    Celano, Umberto E-mail: u.celano@gmail.com; Chintala, Ravi Chandra; Vandervorst, Wilfried; Hantschel, Thomas; Giammaria, Guido; Conard, Thierry; Bender, Hugo

    2015-06-07

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm{sup 2}) of the physical contact (∼100 nm{sup 2}) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.

  11. Evaluation of the electrical contact area in contact-mode scanning probe microscopy

    NASA Astrophysics Data System (ADS)

    Celano, Umberto; Hantschel, Thomas; Giammaria, Guido; Chintala, Ravi Chandra; Conard, Thierry; Bender, Hugo; Vandervorst, Wilfried

    2015-06-01

    The tunneling current through an atomic force microscopy (AFM) tip is used to evaluate the effective electrical contact area, which exists between tip and sample in contact-AFM electrical measurements. A simple procedure for the evaluation of the effective electrical contact area is described using conductive atomic force microscopy (C-AFM) in combination with a thin dielectric. We characterize the electrical contact area for coated metal and doped-diamond tips operated at low force (<200 nN) in contact mode. In both cases, we observe that only a small fraction (<10 nm2) of the physical contact (˜100 nm2) is effectively contributing to the transport phenomena. Assuming this reduced area is confined to the central area of the physical contact, these results explain the sub-10 nm electrical resolution observed in C-AFM measurements.

  12. Contact Precautions for Multidrug-Resistant Organisms (MDROs): Current Recommendations and Actual Practice

    PubMed Central

    Clock, Sarah A.; Cohen, Bevin; Behta, Maryam; Ross, Barbara; Larson, Elaine L.

    2009-01-01

    Background Contact precautions are recommended for interactions with patients colonized/infected with multidrug-resistant organisms; however, rates of contact precautions practice are unknown. Methods Observers recorded the availability of supplies and staff/visitor adherence to contact precautions at rooms of patients indicated for contact precautions. Data were collected at three sites in a New York City hospital network. Results Contact precautions signs were present for 85.4% of indicated patients. The largest proportions were indicated for isolation for vancomycin-resistant enterococci and methicillin-resistant Staphylococcus aureus cultures. Isolation carts were available outside 93.7-96.7% of rooms displaying signs, and personal protective equipment was available at rates of 49.4-72.1% for gloves (all sizes: small, medium, and large) and 91.7-95.2% for gowns. Overall adherence rates upon room entry and exit, respectively, were 19.4% and 48.4% for hand hygiene, 67.5% and 63.5% for gloves, and 67.9% and 77.1% for gowns. Adherence was significantly better in intensive care units (p<0.05) and by patient-care staff (p<0.05), and patient-care staff compliance with one contact precautions behavior was predictive of adherence to additional behaviors (p<0.001). Conclusions Our findings support the recommendation that methods to monitor contact precautions and identify and correct non-adherent practices should be a standard component of infection prevention and control programs. PMID:19913329

  13. Asperity contact theories: Do they predict linearity between contact area and load?

    NASA Astrophysics Data System (ADS)

    Carbone, G.; Bottiglione, F.

    During the last few years, the scientific community has been debating about which theory of contact between rough surfaces can be considered as the most accurate. The authors have been attracted by such a discussion and in this paper try to give their personal thought and contribution to this debate. We present a critical analysis of the principal contact theories of rough surfaces. We focus on the multiasperity contact models (which are all based on the original idea of Greenwood and Williamson (GW) [1966. Proc. R. Soc. London A 295, 300]), and also briefly discuss a relatively recent contact theory developed by Persson [2001. J. Chem. Phys. 115, 3840]. For small loads both asperity contact models and Persson's theory predict a linear relation between the area of true contact and the applied external load, but the two theories differ for the constant of proportionality. However, this is not the only difference between the two approaches. Indeed, we show that the fully calculated predictions of asperity contact models very rapidly deviates from the predicted linear relation already for very small and in many cases unrealistic vanishing applied loads and contact areas. Moreover, this deviation becomes more and more important as the PSD breadth parameter α (as defined by Nayak) increases. Therefore, the asymptotic linear relation of multiasperity contact theories turns out to be only an academic result. On the contrary, Persson's theory is not affected by α and shows a linear behavior between contact area and load up to 10-15% of the nominal contact area, i.e. for physical reasonable loads. The authors also prove that, at high separation, all multiasperity contact models, which take into account the influence of summit curvature variation as a function of summit height, necessarily converge to a (slightly) improved version of the GW model, which, therefore, remains one of the most important milestones in the field of contact mechanics of rough surfaces.

  14. Atomistic effects on friction and contact area in single and multi asperity contacts

    NASA Astrophysics Data System (ADS)

    Luan, Binquan; Robbins, Mark

    2008-03-01

    Contact and friction are universal phenomena in our daily life. Theoretical studies of macroscopic contact and friction are usually based on continuum theories such as Hertz theory and Amontons's laws. Recent advances in nanotechnology have stimulated research into friction at the nanometer scale where new phenomena emerge. Contact and friction in single- and multi-asperity contacts with nanometer dimensions were studied using molecular dynamics simulations (MD) and a hybrid method. The hybrid method retains a full atomistic treatment near contacts and replaces more distant regions with a more efficient finite element description. Our results demonstrate that atomic-scale changes in surface structure produce huge changes in friction and contact area and substantial deviations from the predictions of continuum theories. Unanticipated surface plasticity is observed near peaks on crystalline surfaces. In the case of multiasperity amorphous systems, the rate of local plastic deformation near the surface is directly related to the frictional dissipation of energy.

  15. Contact resistance improvement by the modulation of peripheral length to area ratio of graphene contact pattern

    SciTech Connect

    Cho, Chunhum; Lee, Sangchul; Lee, Sang Kyung; Noh, Jin Woo; Park, Woojin; Lee, Young Gon; Hwang, Hyeon Jun; Ham, Moon-Ho; Kang, Chang Goo; Lee, Byoung Hun

    2015-05-25

    High contact resistance between graphene and metal is a major huddle for high performance electronic device applications of graphene. In this work, a method to improve the contact resistance of graphene is investigated by varying the ratio of peripheral length and area of graphene pattern under a metal contact. The contact resistance decreased to 0.8 kΩ·μm from 2.1 kΩ·μm as the peripheral length increased from 312 to 792 μm. This improvement is attributed to the low resistivity of edge-contacted graphene, which is 8.1 × 10{sup 5} times lower than that of top-contacted graphene.

  16. 97. Cumberland knob recreation area. The visitor contact center originally ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    97. Cumberland knob recreation area. The visitor contact center originally opened in 1941 as a combined sandwich shop, picnic area, and comfort station, the central building of the first recreation area to open looking north. - Blue Ridge Parkway, Between Shenandoah National Park & Great Smoky Mountains, Asheville, Buncombe County, NC

  17. An analytical method for computing atomic contact areas in biomolecules.

    PubMed

    Mach, Paul; Koehl, Patrice

    2013-01-15

    We propose a new analytical method for detecting and computing contacts between atoms in biomolecules. It is based on the alpha shape theory and proceeds in three steps. First, we compute the weighted Delaunay triangulation of the union of spheres representing the molecule. In the second step, the Delaunay complex is filtered to derive the dual complex. Finally, contacts between spheres are collected. In this approach, two atoms i and j are defined to be in contact if their centers are connected by an edge in the dual complex. The contact areas between atom i and its neighbors are computed based on the caps formed by these neighbors on the surface of i; the total area of all these caps is partitioned according to their spherical Laguerre Voronoi diagram on the surface of i. This method is analytical and its implementation in a new program BallContact is fast and robust. We have used BallContact to study contacts in a database of 1551 high resolution protein structures. We show that with this new definition of atomic contacts, we generate realistic representations of the environments of atoms and residues within a protein. In particular, we establish the importance of nonpolar contact areas that complement the information represented by the accessible surface areas. This new method bears similarity to the tessellation methods used to quantify atomic volumes and contacts, with the advantage that it does not require the presence of explicit solvent molecules if the surface of the protein is to be considered. © 2012 Wiley Periodicals, Inc. PMID:22965816

  18. Squeeze elastic deformation and contact area of a rubber adhesive

    NASA Astrophysics Data System (ADS)

    Tordjeman, P.; Papon, E.; Villenave, J.-J.

    2000-12-01

    New experimental results show that the tack energy of a nonstringing rubber adhesive is proportional to the square function of the contact area. However, this area seems only to be controlled by the contact force and the thickness of the adhesive. A study of how the contact area depends on physical parameters is of great interest for the modeling of the tack properties of pressure-sensitive adhesives (PSAs). With this objective, we give a mechanical analysis of the tack test in the framework of elasticity. This analysis leads to an analytical expression of force versus thickness of material that is in agreement with the experimental data. Based on this mechanical analysis, a model is proposed to take into account the dependence of the contact area with the contact force and the adhesive thickness. This model is based on the idea that, in confined geometry, the adhesive behaves like an elastic solid and the contact area is a function of the elastic squeeze deformation close to the probe surface. The confrontation with experimental results is good and shows the relevance of this approach. Finally, the model underlines the importance of the roughness, the thickness and the Young's modulus of the adhesive according to the experimental results.

  19. Effect of 3D fractal dimension on contact area and asperity interactions in elastoplastic contact

    NASA Astrophysics Data System (ADS)

    Jourani, Abdeljalil

    2016-05-01

    Few models are devoted to investigate the effect of 3D fractal dimension Ds on contact area and asperity interactions. These models used statistical approaches or two-dimensional deterministic simulations without considering the asperity interactions and elastic-plastic transition regime. In this study, a complete 3D deterministic model is adopted to simulate the contact between fractal surfaces which are generated using a modified two-variable Weierstrass-Mandelbrot function. This model incorporates the asperity interactions and considers the different deformation modes of surface asperities which range from entirely elastic through elastic-plastic to entirely plastic contact. The simulations reveal that the elastoplastic model is more appropriate to calculate the contact area ratio and pressure field. It is also shown that the influence of the asperity interactions cannot be neglected, especially at lower fractal dimension Ds and higher load.

  20. The effect of elastic modulus on ablation catheter contact area

    NASA Astrophysics Data System (ADS)

    Camp, Jon J.; Linte, Cristian A.; Rettmann, Maryam E.; Sun, Deyu; Packer, Douglas L.; Robb, Richard A.; Holmes, David R.

    2015-03-01

    Cardiac ablation consists of navigating a catheter into the heart and delivering RF energy to electrically isolate tissue regions that generate or propagate arrhythmia. Besides the challenges of accurate and precise targeting of the arrhythmic sites within the beating heart, limited information is currently available to the cardiologist regarding intricate electrodetissue contact, which directly impacts the quality of produced lesions. Recent advances in ablation catheter design provide intra-procedural estimates of tissue-catheter contact force, but the most direct indicator of lesion quality for any particular energy level and duration is the tissue-catheter contact area, and that is a function of not only force, but catheter pose and material elasticity as well. In this experiment, we have employed real-time ultrasound (US) imaging to determine the complete interaction between the ablation electrode and tissue to accurately estimate contact, which will help to better understand the effect of catheter pose and position relative to the tissue. By simultaneously recording tracked position, force reading and US image of the ablation catheter, the differing material properties of polyvinyl alcohol cryogel[1] phantoms are shown to produce varying amounts of tissue depression and contact area (implying varying lesion quality) for equivalent force readings. We have shown that the elastic modulus significantly affects the surface-contact area between the catheter and tissue at any level of contact force. Thus we provide evidence that a prescribed level of catheter force may not always provide sufficient contact area to produce an effective ablation lesion in the prescribed ablation time.

  1. Microscopic contact area and friction between medical textiles and skin.

    PubMed

    Derler, S; Rotaru, G-M; Ke, W; El Issawi-Frischknecht, L; Kellenberger, P; Scheel-Sailer, A; Rossi, R M

    2014-10-01

    The mechanical contact between medical textiles and skin is relevant in the health care for patients with vulnerable skin or chronic wounds. In order to gain new insights into the skin-textile contact on the microscopic level, the 3D surface topography of a normal and a new hospital bed sheet with a regular surface structure was measured using a digital microscope. The topographic data was analysed concerning material distribution and real contact area against smooth surfaces as a function of surface deformations. For contact conditions that are relevant for the skin of patients lying in a hospital bed it was found that the order of magnitude of the ratio of real and apparent contact area between textiles and skin or a mechanical skin model lies between 0.02 and 0.1 and that surface deformations, i.e. penetration of the textile surface asperities into skin or a mechanical skin model, range from 10 to 50µm. The performed analyses of textile 3D surface topographies and comparisons with previous friction measurement results provided information on the relationship between microscopic surface properties and macroscopic friction behaviour of medical textiles. In particular, the new bed sheet was found to be characterised by a trend towards a smaller microscopic contact area (up to a factor of two) and by a larger free interfacial volume (more than a factor of two) in addition to a 1.5 times lower shear strength when in contact with counter-surfaces. The applied methods can be useful to develop improved and skin-adapted materials and surfaces for medical applications. PMID:25047353

  2. Improving contact area between the peritoneum and intraperitoneal therapeutic solutions.

    PubMed

    Flessner, M F; Lofthouse, J; Zakaria, E R

    2001-04-01

    A general assumption in peritoneal dialysis or intraperitoneal chemotherapy has been that a volume of 2 to 3 L in the human is sufficient to make contact with the entire anatomic peritoneum. On the basis of our previous experimental work and that of others, it was hypothesized that only a fraction of the anatomic peritoneum was in contact with the therapeutic solution in the cavity over a short period of time. It was also hypothesized that use of agitation of the experimental animal or a surfactant in the dialysis fluid would increase the contact area of the intraperitoneal solution. These hypotheses were tested by developing a method to measure the peritoneal contact area simultaneously with the anatomic peritoneal area. Anesthetized mice (25 to 35 g) received an injection of a relatively large volume (10 ml) of isotonic solution containing a radiolabeled protein that adhered to the peritoneum with which it came in contact. After a dwell of 1 to 24 h, the animal was killed and frozen. Cross sections of the abdominal and pelvic cavities were cut and placed against film to develop into autoradiograms, which represent the linear dimension of fluid contact in each sampling plane. The tissue sections that corresponded to the autoradiograms were stained to display the linear dimension of the anatomic peritoneum in the sampling plane. By imaging both the autoradiogram and the corresponding histologic slide, an estimate of the ratio of the contact area to anatomic area in each plane can be calculated (R(mean) = average of all ratios). Applying this method to mice that were dialyzed with an isotonic salt solution under quiescent conditions for 1 h produced R(mean) = 0.43 +/- 0.03. With rapid shaking of the animal, R(mean) = 0.54 +/- 0.03 (P: < 0.05). Addition of the surfactant dioctyl sodium sulfosuccinate (DSS) 0.5% to the solution under quiescent conditions increased R(mean) to 1.07 +/- 0.03 (P: < 0.001). Lengthening the dwell of the isotonic solution to 24 h increased R

  3. Minimal adhesion surface area in tangentially loaded digital contacts.

    PubMed

    Terekhov, Alexander V; Hayward, Vincent

    2011-09-01

    The stick-to-slip transition of a fingertip in contact with a planar surface does not occur instantaneously. As the tangential load increases, portions of the skin adhere while others slip, giving rise to an evolution of the contact state, termed partial slip. We develop a quasi-static model that predicts that if the coefficient of kinetic friction is larger than the coefficient of static friction, then the stuck surface area diminishes as the tangential load increases until reaching a 'minimal adhesion surface area' where it vanishes abruptly. This phenomenon was observed in recently measured finger-slip image data (André et al., 2011) that were processed by an optic flow detection algorithm. We examined the results of 10 trials. Four of them exhibited the minimal adhesion surface area phenomenon, four of them did not, and two were inconclusive. PMID:21774936

  4. Increasing peritoneal contact area during dialysis improves mass transfer.

    PubMed

    Flessner, M F; Lofthouse, J; Williams, A

    2001-10-01

    Previous studies in mice demonstrated that relatively large volumes in the peritoneal cavity made contact with only 40% of the anatomic peritoneum and that this contact area (A(contact)) could be increased with use of a surfactant, dioctyl sodium sulfosuccinate (DSS). To investigate the hypothesis that mass transfer rates during peritoneal dialysis are dependent on the area of peritoneum in contact with the dialysis solution, rats were dialyzed for 2 h with a solution that contained (14)C-mannitol, with or without 0.02% DSS. The mass transfer-area coefficients (MTAC) were determined to be (mean +/- SEM, ml/min): no DSS, 0.163 +/- 0.008; with DSS, 0.247 +/- 0.006 (P < 0.002). DSS also caused an increase in total protein loss over 2 h (mean +/- SEM, mg): no DSS, 83.8 +/- 15.8; DSS, 159.5 +/- 6.3 (P < 0.001). In a separate set of animals, the ratio (R) of A(contact) to anatomic area in each plane was measured as in the previous study R(mean) (mean +/- SEM) and equaled 0.466 +/- 0.075, no DSS; 0.837 +/- 0.074, with DSS. The ratio of MTAC (1.52) and protein loss (1.90) approximate the ratio of R(mean(S)) (1.78). Because MTAC = mass transfer coefficient (MTC) x A(contact), small peritoneal transport chambers were used to determine MTC for (14)C-mannitol and fluorescein isothiocyanate-albumin. MTC(mannitol) did not change significantly with the addition of DSS. MTC(albumin) (cm/min x 10(4), mean +/- SEM) equaled 1.47 +/- 0.45 without DSS and 1.78 +/- 0.52 with DSS (P < 0.04). It was concluded that DSS increases the mass transfer rates of mannitol and protein by increasing A(contact), whereas protein transport is further augmented by an apparent increase in the barrier permeability to protein. PMID:11562413

  5. Bubbles trapped in a fluidized bed: Trajectories and contact area

    NASA Astrophysics Data System (ADS)

    Poryles, Raphaël; Vidal, Valérie; Varas, Germán

    2016-03-01

    This work investigates the dynamics of bubbles in a confined, immersed granular layer submitted to an ascending gas flow. In the stationary regime, a central fluidized zone of parabolic shape is observed, and the bubbles follow different dynamics: either the bubbles are initially formed outside the fluidized zone and do not exhibit any significant motion over the experimental time or they are located inside the fluidized bed, where they are entrained downwards and are, finally, captured by the central air channel. The dependence of the air volume trapped inside the fluidized zone, the bubble size, and the three-phase contact area on the gas injection flow rate and grain diameter are quantified. We find that the volume fraction of air trapped inside the fluidized region is roughly constant and of the order of 2%-3% when the gas flow rate and the grain size are varied. Contrary to intuition, the gas-liquid-solid contact area, normalized by the air injected into the system, decreases when the flow rate is increased, which may have significant importance in industrial applications.

  6. In-situ studies of cartilage microtribology: roles of speed and contact area

    PubMed Central

    Bonnevie, E.D.; Baro, V.; Wang, L.; Burris, D.L.

    2011-01-01

    suggest that joint motion is actually beneficial for maintaining low matrix stresses, low contact areas, and effective lubrication for the fluid-saturated porous cartilage tissue. Further, the results demonstrated effective pressurization and lubrication beneath single asperity microscale contacts. With carefully designed experimental conditions, local friction probes can facilitate more fundamental studies of cartilage lubrication, friction and wear, and potentially add important insights into the mechanical mechanisms of OA. PMID:21765622

  7. Retrieved actual ET using SEBS model from Landsat-5 TM data for irrigation area of Australia

    NASA Astrophysics Data System (ADS)

    Ma, Weiqiang; Hafeez, Mohsin; Rabbani, Umair; Ishikawa, Hirohiko; Ma, Yaoming

    2012-11-01

    The idea of ground-based evapotranspiration (ET) is of the most interesting for land-atmosphere interactions, such as water-saving irrigation, the performance of irrigation systems, crop water deficit, drought mitigation strategies and accurate initialization of climate prediction models especially in arid and semiarid catchments where water shortage is a critical problem. The recent year's drought in Australia and concerns about climate change has prominent the need to manage water resources more sustainably especially in the Murrumbidgee catchment which utilizes bulk water for food security and production. This paper discusses the application of a Surface Energy Balance System (SEBS) model based on Landsat-5 TM data and field observations has been used and tested for deriving ET over Coleambally Irrigation Area (CIA), located in the southwest of NSW, Australia. 16 Landsat-5 TM scenes were selected covering the time period of 2009, 2010 and 2011 for estimating the actual ET in CIA. To do the validation the used methodology, the ground-measured ET was compared to the Landsat-5 TM retrieved actual ET results for CIA. The derived ET value over CIA is much closer to the field measurement. From the remote sensing results and observations, the root mean square error (RMSE) is 0.74 and the mean APD is 7.5%. The derived satellite remote sensing values belong to reasonable range.

  8. Influences of spherical tip radius, contact depth, and contact area on nanoindentation properties of bone.

    PubMed

    Paietta, Rachel C; Campbell, Sara E; Ferguson, Virginia L

    2011-01-11

    Nanoindentation has been widely used as a means to measure the micro-mechanical properties of bone and to predict the macroscopic properties. The role of indent depth and indenter tip geometry in measuring the hierarchical properties of bone tissue was explored experimentally using a range of spherical indenter tips of R=5, 25, 65, and 200 μm. Nanoindentation arrays, not targeted to fall on specific structures or locations, enabled statistical sampling of osteons within PMMA-embedded, bovine, cortical bone on a single sample to a range of maximum displacements (minimum of 100 nm and maximum of 2000 nm). Elastic finite element models were then utilized to isolate the contributions of indenter tip radius, contact area, and position within the lamellar structure in comparison to the experimental results. For a small, R=5 μm indenter tip, indentation modulus consistently increased with contact depth and increased plastic deformation, resulting in an artificial increase in elastic properties. While larger radius tips (R=25, 65, and 200 μm) did not enable evaluation of a high spatial resolution on the surface, they produced data that was representative of the lower load and contact depth measurements with the smaller tip. However the sensitivity to mechanical property variations across the 2-D surface of the material was lost with increase in indenter tip size. Correspondingly, measurement variance was also decreased as the volume contributing to the indent response represented an average of surface roughness, varying mineral content, defects, and underlying tissue type and structure. PMID:21092970

  9. Effect of load, area of contact, and contact stress on the wear mechanisms of a bonded solid lubricant film

    NASA Technical Reports Server (NTRS)

    Fusaro, R. L.

    1980-01-01

    A pin on disk type of friction and wear apparatus was used to study the effect of load, contact stress and rider area of contact on the friction and wear properties of polyimide bonded graphite fluoride films. Different rider area contacts were obtained by initially generating flats (with areas of 0.0035, 0.0071, 0.0145, and 0.0240 cm) on 0.476-cm radius hemispherically tipped riders. Different projected contact stresses were obtained by applying loads of 2.5- to 58.8-N to the flats. Two film wear mechanisms were observed. The first was found to be a linear function of contact stress and was independent of rider area of contact. The second was found to increase exponentially as the stress increased. The second also appeared to be a function of rider contact area. Wear equations for each mechanism were empirically derived from the experimental data. In general, friction coefficients increased with increasing rider contact area and with sliding duration. This was related to the build up of thick rider transfer films.

  10. Contact area as the intuitive definition of contact CD based on aerial image analysis

    NASA Astrophysics Data System (ADS)

    Polonsky, Netanel; Sagiv, Amir; Mangan, Shmoolik

    2009-03-01

    As feature sizes continue to diminish, optical lithography is driven into the extreme low-k1 regime, where the high MEEF increasingly complicates the relationship between the mask pattern and the aerial image. This is true in particular for twodimensional mask patterns, which are by nature much more complicated than patterns possessing one-dimensional symmetry. Thus, the intricacy of 2D image formation typically requires a much broader arsenal of resolution enhancement techniques over complex phase shift masks, including SRAFs and OPC, as well as exotic off-axis illumination geometries. This complexity on the mask side makes the printability effect of a random defect on a 2D pattern a field of rich and delicate phenomenology. This complexity is reflected in the dispute over the CD definition of 2D patterns: some sources use the X and Y values, while others use the contact area. Here, we argue that for compact features, for which the largest dimension is not wider than the PSF of the stepper optics, the area definition is the natural one. We study the response of the aerial image to small perturbations in mask pattern. We show that any perturbation creates an effect extending in all directions, thus affecting the area and not the size in a single direction. We also show that, irrespective of the source of perturbation, the aerial signal is proportional to the variation in the area of the printed feature. The consequence of this effect is that aerial inspection signal scales linearly with the variation of printed area of the tested feature.

  11. A Novel Algorithm for Determining Contact Area Between a Respirator and a Headform

    PubMed Central

    Lei, Zhipeng; Yang, James; Zhuang, Ziqing

    2016-01-01

    The contact area, as well as the contact pressure, is created when a respiratory protection device (a respirator or surgical mask) contacts a human face. A computer-based algorithm for determining the contact area between a headform and N95 filtering facepiece respirator (FFR) was proposed. Six N95 FFRs were applied to five sizes of standard headforms (large, medium, small, long/narrow, and short/wide) to simulate respirator donning. After the contact simulation between a headform and an N95 FFR was conducted, a contact area was determined by extracting the intersection surfaces of the headform and the N95 FFR. Using computer-aided design tools, a superimposed contact area and an average contact area, which are non-uniform rational basis spline (NURBS) surfaces, were developed for each headform. Experiments that directly measured dimensions of the contact areas between headform prototypes and N95 FFRs were used to validate the simulation results. Headform sizes influenced all contact area dimensions (P < 0.0001), and N95 FFR sizing systems influenced all contact area dimensions (P < 0.05) except the left and right chin regions. The medium headform produced the largest contact area, while the large and small headforms produced the smallest. PMID:24579752

  12. A novel algorithm for determining contact area between a respirator and a headform.

    PubMed

    Lei, Zhipeng; Yang, James; Zhuang, Ziqing

    2014-01-01

    The contact area, as well as the contact pressure, is created when a respiratory protection device (a respirator or surgical mask) contacts a human face. A computer-based algorithm for determining the contact area between a headform and N95 filtering facepiece respirator (FFR) was proposed. Six N95 FFRs were applied to five sizes of standard headforms (large, medium, small, long/narrow, and short/wide) to simulate respirator donning. After the contact simulation between a headform and an N95 FFR was conducted, a contact area was determined by extracting the intersection surfaces of the headform and the N95 FFR. Using computer-aided design tools, a superimposed contact area and an average contact area, which are non-uniform rational basis spline (NURBS) surfaces, were developed for each headform. Experiments that directly measured dimensions of the contact areas between headform prototypes and N95 FFRs were used to validate the simulation results. Headform sizes influenced all contact area dimensions (P < 0.0001), and N95 FFR sizing systems influenced all contact area dimensions (P < 0.05) except the left and right chin regions. The medium headform produced the largest contact area, while the large and small headforms produced the smallest. PMID:24579752

  13. Exposure to Schistosoma mansoni infection in a rural area of Brazil. I: water contact.

    PubMed

    Gazzinelli, A; Bethony, J; Fraga, L A; LoVerde, P T; Correa-Oliveira, R; Kloos, H

    2001-02-01

    The study of water contact patterns in rural Brazil presents unique challenges due to widely dispersed settlement patterns, the ubiquity of water contact sites, and the privatization of water resources. This study addresses these challenges by comparing the two most widely used methods of assessing water contact behaviour: direct observation and survey. The results of a 7-day direct observation of water contact were compared with water contact surveys administered 1 week after and then 1 year after the direct observation study. The direct observation study recorded a water contact rate higher than reported by other investigators (3.2 contacts per person per day); however, 75% of these contacts were for females and consisted mainly of domestic activities occurring around the household. A comparison of the frequency of water contact activities between the direct observation and the two surveys revealed several important points. First, no significant differences were found between methods for routine water contact activities (e.g. bathing), indicating that participants were able to accurately self-report some types of water contact activities. Second, significant differences were found in the recording of water contact activities that took place outside the observation area, indicating that direct observation may under-report water contact activities in areas where contact sites are dispersed widely. Third, significant differences between the direct observation and the survey method were more common for males than for females, indicating that the combination of widespread water contact sites and gender-specific division of labour may result in under-reporting of male contacts by direct observation methods. In short, despite the limitations in the recording of duration and body exposure, the survey method may more accurately record the frequency of water contact activities than direct observation methods in areas of widely dispersed water contact sites. Hence, surveys

  14. Experimental and numerical investigation of contact-area-limited doping for top-contact pentacene thin-film transistors with Schottky contact.

    PubMed

    Noda, Kei; Wada, Yasuo; Toyabe, Toru

    2015-10-28

    Effects of contact-area-limited doping for pentacene thin-film transistors with a bottom-gate, top-contact configuration were investigated. The increase in the drain current and the effective field-effect mobility was achieved by preparing hole-doped layers underneath the gold contact electrodes by coevaporation of pentacene and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), confirmed by using a thin-film organic transistor advanced simulator (TOTAS) incorporating Schottky contact with a thermionic field emission (TFE) model. Although the simulated electrical characteristics fit the experimental results well only in the linear regime of the transistor operation, the barrier height for hole injection and the gate-voltage-dependent hole mobility in the pentacene transistors were evaluated with the aid of the device simulation. This experimental data analysis with the simulation indicates that the highly-doped semiconducting layers prepared in the contact regions can enhance the charge carrier injection into the active semiconductor layer and concurrent trap filling in the transistor channel, caused by the mitigation of a Schottky energy barrier. This study suggests that both the contact-area-limited doping and the device simulation dealing with Schottky contact are indispensable in designing and developing high-performance organic thin-film transistors. PMID:24922359

  15. Assessment of actual transpiration rate in olive tree field combining sap-flow, leaf area index and scintillometer measurements

    NASA Astrophysics Data System (ADS)

    Agnese, C.; Cammalleri, C.; Ciraolo, G.; Minacapilli, M.; Provenzano, G.; Rallo, G.; de Bruin, H. A. R.

    2009-09-01

    Models to estimate the actual evapotranspiration (ET) in sparse vegetation area can be fundamental for agricultural water managements, especially when water availability is a limiting factor. Models validation must be carried out by considering in situ measurements referred to the field scale, which is the relevant scale of the modelled variables. Moreover, a particular relevance assumes to consider separately the components of plant transpiration (T) and soil evaporation (E), because only the first is actually related to the crop stress conditions. Objective of the paper was to assess a procedure aimed to estimate olive trees actual transpiration by combining sap flow measurements with the scintillometer technique at field scale. The study area, located in Western Sicily (Italy), is mainly cultivated with olive crop and is characterized by typical Mediterranean semi-arid climate. Measurements of sap flow and crop actual evapotranspiration rate were carried out during 2008 irrigation season. Crop transpiration fluxes, measured on some plants by means of sap flow sensors, were upscaled considering the leaf area index (LAI). The comparison between evapotranspiration values, derived by displaced-beam small-aperture scintillometer (DBSAS-SLS20, Scintec AG), with the transpiration fluxes obtained by the sap flow sensors, also allowed to evaluate the contribute of soil evaporation in an area characterized by low vegetation coverage.

  16. Estimation of real contact area during sliding friction from interface temperature

    NASA Astrophysics Data System (ADS)

    Chey, Sung Keun; Tian, Pengyi; Tian, Yu

    2016-06-01

    Frictional heat is one of the most important topics in tribological research. The real contact area of the frictional pair plays a significant role in accurately estimating the interface temperature, which is closely related to the frictional heat. However, conventional methods for measuring the contact area, such as constriction resistance measurements, are not suitable for dynamic frictional motion because of the electrical and thermal interferences at the contact region. In this study, a novel method is presented for estimating the real contact area during sliding friction. First, the average interface temperature was experimentally measured by the dynamic thermocouple method. Then assuming that the total frictional heat power is constant, the measured temperature was used as a constraint to determine the contact area in a finite element model, giving an estimation for the real contact area. The calculation results show that the real contact area increases with increasing normal load as predicted by contact theories, and decreases with increasing sliding speed, which could be attributable to the contact dynamics of asperities at the interface. Additionally, the limits of the proposed method is discussed.

  17. Analysis of main parameters affecting substrate/mortar contact area through tridimensional laser scanner.

    PubMed

    Stolz, Carina M; Masuero, Angela B

    2015-10-01

    This study assesses the influence of the granulometric composition of sand, application energy and the superficial tension of substrates on the contact area of rendering mortars. Three substrates with distinct wetting behaviors were selected and mortars were prepared with different sand compositions. Characterization tests were performed on fresh and hardened mortars, as well as the rheological characterization. Mortars were applied to substrates with two different energies. The interfacial area was then digitized with 3D scanner. Results show that variables are all of influence on the interfacial contact in the development area. Furthermore, 3D laser scanning proved to be a good method to contact area measurement. PMID:26046982

  18. Evaluation of SEBS for estimation of actual evapotranspiration using ASTER satellite data for irrigation areas of Australia

    NASA Astrophysics Data System (ADS)

    Ma, Weiqiang; Hafeez, Mohsin; Ishikawa, Hirohiko; Ma, Yaoming

    2013-05-01

    Spatial knowledge of land surface evapotranspiration (ET) is of prime interest for environmental applications, such as optimizing irrigation water use, irrigation system performance, crop water deficit, drought mitigation strategies, and accurate initialization of climate prediction models especially in arid and semiarid catchments where water shortage is a critical problem. The recent drought in Australia and concerns about climate change have highlighted the need to manage water resources more sustainably especially in the Murrumbidgee catchment which utilizes bulk water for food production. This study deals with the application of a Surface Energy Balance System (SEBS) algorithm based on Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) data and field observations has been proposed and tested for deriving ET over Coleambally Irrigation Area, located in the southwest of NSW, Australia. We have used 12 ASTER scenes covering the time period of 2002, 2003, 2004, 2005, 2006, and 2009 for estimating the actual ET over the study area. To validate the proposed methodology, the ground-measured ET was compared to the ASTER-derived actual ET values for the study area. The derived ET value over the study area is much closer to the field measurement. From the remote sensing results and observations, the root mean square error is 0.89 and the mean absolute percentage difference is 2.87 %, which demonstrate the reasonability of SEBS ET estimation for the study area.

  19. Large-Eddy Simulation of plume dispersion within various actual urban areas

    NASA Astrophysics Data System (ADS)

    Nakayama, H.; Jurcakova, K.; Nagai, H.

    2013-02-01

    Plume dispersion of hazardous materials within urban area resulting from accidental or intentional releases is of great concern to public health. Many researchers have developed local-scale atmospheric dispersion models using building-resolving computational fluid dynamics. However, an important issue is encountered when determining a reasonable domain size of the computational model in order to capture concentration distribution patterns influenced by urban surface geometries. In this study, we carried out Large-Eddy Simulations (LES) of plume dispersion within various urban areas with a wide range of obstacle density and building height variability. The difference of centerline mean and r.m.s. concentration distributions among various complex urban surface geometries becomes small for downwind distances from the point source greater than 1.0 km. From these results, it can be concluded that a length of a computational model should be at least 1.0 km from a point source.

  20. An in-situ sensor to measure contact area and surface stresses between real tribological bodies

    SciTech Connect

    Bryant, M.D.; Fernandez, B.

    1996-11-01

    Many machine components such as rollers (bearings and gears) and sliders (brushes and brakes) have elements with surfaces in contact. Failure is often by fatigue from contact stresses. Measurement of these stresses could reduce maintenance costs and avoid catastrophic failures. Common manufacturing techniques such as extruding, pressing and punching employ dies with surface contact. Direct and real time measurement of contact stresses within the dies could lead to improved process control through real time control feedback. Presented will be the concept of an in-situ sensor to visualize and measure real contact areas and surface stresses at all points within a contact interface. The sensor generates photoelastic fringes (fields of light intensity values) which it converts into surface stresses. First presented will be photoelastic principles and sensor operation; photographs of fringes taken under various contact conditions; measurements of real contact area extracted from these photographs; and calculations that relate the fringes to the contact stresses. These forward calculations map fields of contact stresses (input data) to fields of photoelastic light intensity values (output data). To extract surface stresses from light intensity measurements, Artificial Neural Networks generate an inverse map. Network architectures will be presented and training procedures discussed.

  1. Water Purification Characteristic of the Actual Constructed Wetland with Carex dispalata in a Cold Area

    NASA Astrophysics Data System (ADS)

    Tsuji, Morio; Yamada, Kazuhiro; Hiratsuka, Akira; Tsukada, Hiroko

    Carex dispalata, a native plant species applied in cold districts for water purification in constructed wetlands, has useful characteristics for landscape creation and maintenance. In this study, seasonal differences in purification ability were verified, along with comparison of frozen and non-frozen periods' performance. A wetland area was constructed using a “hydroponics method” and a “coir fiber based method”. Results show that the removal rates of BOD, SS, and Chl-a were high. On this constructed wetland reduces organic pollution, mainly phytoplankton, but the removal of nitrogen and phosphorus was insufficient. The respective mean values of influent and treated water during three years were 26.6 mg/L and 12.2 mg/L for BOD, and 27.9 mg/L and 7.5 mg/L for SS. The mean value of the BOD removal rate for the non-frozen period was 2.99 g/m2/d that for the frozen period was 1.86 g/m2/d. The removal rate followed the rise of the BOD load rate. The removal rate limits were about 4 g/m2/d during the frozen period and 15 g/m2/d during the non-frozen period. For operations, energy was unnecessary. The required working hours were about 20 h annually for all maintenance and management during operations.

  2. Simultaneous measurement of real contact area and fault normal stiffness during frictional sliding

    NASA Astrophysics Data System (ADS)

    Beeler, N. M.; Nagata, K.; Kilgore, B. D.; Nakatani, M.

    2010-12-01

    The tectonic stresses that lead to earthquake slip are concentrated in small regions of solid contact between asperities or gouge particles within the fault. Fault strength is proportional to the contact area within the shearing portion of the fault zone and many fault properties of interest to earthquake hazard research, e.g., occurrence time, recurrence interval, precursory slip, triggered earthquake slip, are controlled by processes acting at the highly stressed contact regions. Unfortunately the contact-scale physical processes controlling earthquake occurrence cannot be easily observed or measured directly. In this pilot study we simultaneously directly measure contact area using transmitted light intensity (LI) [Dieterich and Kilgore, 1994; 1996] and continuously monitor the normal stiffness of the fault using acoustic wave transmission (AT) [Nagata et al., 2008]. The objective of our study is to determine relations amongst contacting area, stiffness, strength, normal stress, shear displacement, and time of contact during sliding. Interface stiffness is monitored using acoustic compressive waves transmitted across the fault. Because the fault is more compliant in compression than the surrounding rock, the fault has an elastic wave transmission coefficient that depends on the fault normal stiffness. Contact area is measured by LI: regions in contact transmit light efficiently while light is scattered elsewhere; therefore transmitted light intensity is presumed proportional to contact area. LI and AT are expected to be correlated; e.g., an elastic contact model suggests that stiffness goes as the square root of contact area. We observe LI and AT for sliding at slip speeds between 0.01 and 10 microns/s and normal stresses between 1 and 2.5 MPa while conducting standard velocity-step, normal stress-step and slide-hold-slide tests. AT and LI correlate during all tests, at all conditions. If the physical relationship, or even an empirical calibration between AT and

  3. Contact area and static pressure profile at the plate-bone interface in the nonluted and luted bone plate.

    PubMed

    Staller, G S; Richardson, D W; Nunamaker, D M; Provost, M

    1995-01-01

    Contact area and pressure between 6-hole broad dynamic compression plates and 20 pairs of equine third metatarsal bones were measured using nonluted and luted plating techniques. Pressure-sensitive film (pressure ranges 10 to 50 MPa and 50 to 130 MPa) was used as the static pressure transducer. Nonluted and one of two luting techniques were tested on each pair of bones; each luting technique was tested on 20 bones. Quantitative determinations of contact area and pressure were made using computerized image processing techniques. Mean (+/- SD) total contact area for nonluted plates was 18.49% +/- 3.5% of the potential plate-bone contact area. Luting increased (P < .05) total contact area to 25.56% +/- 4.0% and 31.29% +/- 6.6% for the respective luting techniques. The effects of luting on contact area were dependent on the contact pressure. At contact pressure ranges 10 to 20 and 21 to 35 MPa, luting increased contact area. In contact pressure ranges 36 to 45 and 50 to 65 MPa, plate-bone contact was inherently greatest and plate luting had no significant effect on contact area. In contact pressure ranges 66 to 99 and 100 to 126 MPa, luting decreased contact area. Contact area was increased at lower contact pressures at the expense of higher pressure contact. Contact in the middle third of the plate was 20% to 40% of the contact at either end of the plate. Plate luting increased contact area best where plate-bone contour was most similar. PMID:7571381

  4. Clinical measurement of the height of the interproximal contact area in maxillary anterior teeth

    PubMed Central

    Sghaireen, Mohd G.; Al-Zarea, Bader K.; Al-Shorman, Hisham M.; AL-Omiri, Mahmoud K.

    2013-01-01

    Objectives To clinically quantify the apicoincisal height of interproximal areas directly in patients’ mouths. Methodology Thirty participants (11 females and 9 males, mean age=26±1.5 years) were recruited into this study. Measurement of interproximal contact areas was carried out directly in patients’ mouths using digital caliper (TERENSA, USA) with measuring accuracy of 0.01 mm. The interproximal contact areas that were measured are: central incisor to central incisor, central incisor to lateral incisor, lateral incisor to canine, and canine to first premolar on both sides of the jaw. Statistical significance was based on probability values less than 0.05 (p<0.05). Results The largest contact point was the one present between central incisors and it ranged from 2.9 to 6.5 mm. On the other hand, the contact point between canine and first premolar was the smallest on both sides of the arch and ranged from 0.6 to 2.5 mm. The dimensions of the contact points declined as we move from anterior area backwards. Statistical analysis using t-test showed that there were significant differences between the measurements of interproximal points of each tooth (P<0.05). Conclusions the apicogingival dimension of the contact point decreased as we moved from anterior to posterior teeth. The contact area between the central incisors was largest and the one between canine and premolar was the smallest. This study is the first to report direct intra-oral clinical measurement of contact points. Clinical evaluation of contact point dimensions using digital caliber is a viable, quick and accurate method to use. PMID:24533026

  5. Effects of fracture contact areas on seismic attenuation due to wave-induced fluid flow

    NASA Astrophysics Data System (ADS)

    Germán Rubino, J.; Müller, Tobias M.; Milani, Marco; Holliger, Klaus

    2014-05-01

    Wave-induced fluid flow (WIFF) between fractures and the embedding matrix is considered to be a predominant seismic attenuation mechanism in fractured rocks. That is, due to the strong compressibility contrast between fractures and embedding matrix, seismic waves induce strong fluid pressure gradients, followed by local fluid flow between such regions, which in turn produces significant energy dissipation. Natural fractures can be conceptualized as two surfaces in partial contact, containing very soft and highly permeable material in the inner region. It is known that the characteristics of the fracture contact areas control the mechanical properties of the rock sample, since as the contact area increases, the fracture becomes stiffer. Correspondingly, the detailed characteristics of the contact area of fractures are expected to play a major role in WIFF-related attenuation. To study this topic, we consider a simple model consisting of a horizontal fracture located at the center of a porous rock sample and represented by a number of rectangular cracks of constant height separated by contact areas. The cracks are modelled as highly compliant, porous, and permeable heterogeneities, which are hydraulically connected to the background material. We include a number of rectangular regions of background material separating the cracks, which represent the presence of contact areas of the fracture. In order to estimate the WIFF effects, we apply numerical oscillatory relaxation tests based on the quasi-static poro-elastic equations. The equivalent undrained, complex plane-wave modulus, which allows to estimate seismic attenuation and velocity dispersion for the vertical direction of propagation, is expressed in terms of the imposed displacement and the resulting average vertical stress at the top boundary. In order to explore the effects of the presence of fracture contact areas on WIFF effects, we perform an exhaustive sensitivity analysis considering different

  6. The Preference and Actual Use of Different Types of Rural Recreation Areas by Urban Dwellers—The Hamburg Case Study

    PubMed Central

    Boll, Thiemen; von Haaren, Christina; von Ruschkowski, Eick

    2014-01-01

    In the wake of urbanisation processes and the constitution of metropolitan regions, the role of the city's rural surroundings is receiving more attention from researchers and planners as rural areas offer various (cultural) ecosystem services for the urban population. Urban dwellers increasingly desire recreation and landscape experience. Although this need for recreation is generally recognized, few studies have focused on the question of people's preferences for certain types and characteristics of outdoor recreation areas in relation to the frequency of use. In order to acquire baseline data on this subject, the main objectives of this study were to explore recreation preferences of urban dwellers and the relation between actual use and perceived value of recreation areas in a case study in the Hamburg Metropolitan Region (Germany). In a social survey, Hamburg residents (n = 400) were asked about their preferences and use of four important regional recreation areas with different landscape characteristics in face-to-face interviews in different locations in the city. We found that both outdoor recreation within and outside of the city were fairly or very important for more than 70% of the questioned urban dwellers. Interestingly, the preference for a recreation area outside of the city did not depend on the frequency of use, which indicates that certain recreation areas had a symbolic value besides their use value. When people were questioned on the characteristics of recreation areas, perceived naturalness was found to be strongly related to preference. Respondents considered the diversity, uniqueness, and naturalness of the landscape to be far more important than the accessibility of the recreation areas and the provision of service facilities. PMID:25314002

  7. The preference and actual use of different types of rural recreation areas by urban dwellers--the Hamburg case study.

    PubMed

    Boll, Thiemen; von Haaren, Christina; von Ruschkowski, Eick

    2014-01-01

    In the wake of urbanisation processes and the constitution of metropolitan regions, the role of the city's rural surroundings is receiving more attention from researchers and planners as rural areas offer various (cultural) ecosystem services for the urban population. Urban dwellers increasingly desire recreation and landscape experience. Although this need for recreation is generally recognized, few studies have focused on the question of people's preferences for certain types and characteristics of outdoor recreation areas in relation to the frequency of use. In order to acquire baseline data on this subject, the main objectives of this study were to explore recreation preferences of urban dwellers and the relation between actual use and perceived value of recreation areas in a case study in the Hamburg Metropolitan Region (Germany). In a social survey, Hamburg residents (n = 400) were asked about their preferences and use of four important regional recreation areas with different landscape characteristics in face-to-face interviews in different locations in the city. We found that both outdoor recreation within and outside of the city were fairly or very important for more than 70% of the questioned urban dwellers. Interestingly, the preference for a recreation area outside of the city did not depend on the frequency of use, which indicates that certain recreation areas had a symbolic value besides their use value. When people were questioned on the characteristics of recreation areas, perceived naturalness was found to be strongly related to preference. Respondents considered the diversity, uniqueness, and naturalness of the landscape to be far more important than the accessibility of the recreation areas and the provision of service facilities. PMID:25314002

  8. Contact area of rough spheres: Large scale simulations and simple scaling laws

    NASA Astrophysics Data System (ADS)

    Pastewka, Lars; Robbins, Mark O.

    2016-05-01

    We use molecular simulations to study the nonadhesive and adhesive atomic-scale contact of rough spheres with radii ranging from nanometers to micrometers over more than ten orders of magnitude in applied normal load. At the lowest loads, the interfacial mechanics is governed by the contact mechanics of the first asperity that touches. The dependence of contact area on normal force becomes linear at intermediate loads and crosses over to Hertzian at the largest loads. By combining theories for the limiting cases of nominally flat rough surfaces and smooth spheres, we provide parameter-free analytical expressions for contact area over the whole range of loads. Our results establish a range of validity for common approximations that neglect curvature or roughness in modeling objects on scales from atomic force microscope tips to ball bearings.

  9. Prediction of bead area contact load at the tire-wheel interface using NASTRAN

    NASA Technical Reports Server (NTRS)

    Chen, C. H. S.

    1982-01-01

    The theoretical prediction of the bead area contact load at the tire wheel interface using NASTRAN is reported. The application of the linear code to a basically nonlinear problem results in excessive deformation of the structure and the tire-wheel contact conditions become impossible to achieve. A psuedo-nonlinear approach was adopted in which the moduli of the cord reinforced composite are increased so that the computed key deformations matched that of the experiment. Numerical results presented are discussed.

  10. Modeling Thermal Contact Resistance

    NASA Technical Reports Server (NTRS)

    Kittel, Peter; Sperans, Joel (Technical Monitor)

    1994-01-01

    One difficulty in using cryocoolers is making good thermal contact between the cooler and the instrument being cooled. The connection is often made through a bolted joint. The temperature drop associated with this joint has been the subject of many experimental and theoretical studies. The low temperature behavior of dry joints have shown some anomalous dependence on the surface condition of the mating parts. There is also some doubts on how well one can extrapolate from the test samples to predicting the performance of a real system. Both finite element and analytic models of a simple contact system have been developed. The model assumes (a) the contact is dry (contact limited to a small portion of the total available area and the spaces in-between the actual contact patches are perfect insulators), (b) contacts are clean (conductivity of the actual contact is the same as the bulk), (c) small temperature gradients (the bulk conductance may be assumed to be temperature independent), (d) the absolute temperature is low (thermal radiation effects are ignored), and (e) the dimensions of the nominal contact area are small compared to the thickness of the bulk material (the contact effects are localized near the contact). The models show that in the limit of actual contact area much less than the nominal area (a much less than A), that the excess temperature drop due to a single point of contact scales as a(exp -1/2). This disturbance only extends a distance approx. A(exp 1/2) into the bulk material. A group of identical contacts will result in an excess temperature drop that scales as n(exp -1/2), where n is the number of contacts and n dot a is constant. This implies that flat rough surfaces will have a lower excess temperature drop than flat polished surfaces.

  11. The Change in Fingertip Contact Area as a Novel Proprioceptive Cue

    PubMed Central

    Moscatelli, Alessandro; Bianchi, Matteo; Serio, Alessandro; Terekhov, Alexander; Hayward, Vincent; Ernst, Marc O.; Bicchi, Antonio

    2016-01-01

    Summary Humans, many animals, and certain robotic hands have deformable fingertip pads [1, 2]. Deformable pads have the advantage of conforming to the objects that are being touched, ensuring a stable grasp for a large range of forces and shapes. Pad deformations change with finger displacements during touch. Pushing a finger against an external surface typically provokes an increase of the gross contact area [3], potentially providing a relative motion cue, a situation comparable to looming in vision [4]. The rate of increase of the area of contact also depends on the compliance of the object [5]. Because objects normally do not suddenly change compliance, participants may interpret an artificially induced variation in compliance, which coincides with a change in the gross contact area, as a change in finger displacement, and consequently they may misestimate their finger’s position relative to the touched object. To test this, we asked participants to compare the perceived displacements of their finger while contacting an object varying pseudo-randomly in compliance from trial to trial. Results indicate a bias in the perception of finger displacement induced by the change in compliance, hence in contact area, indicating that participants interpreted the altered cutaneous input as a cue to proprioception. This situation highlights the capacity of the brain to take advantage of knowledge of the mechanical properties of the body and of the external environment. PMID:27068417

  12. The Change in Fingertip Contact Area as a Novel Proprioceptive Cue.

    PubMed

    Moscatelli, Alessandro; Bianchi, Matteo; Serio, Alessandro; Terekhov, Alexander; Hayward, Vincent; Ernst, Marc O; Bicchi, Antonio

    2016-05-01

    Humans, many animals, and certain robotic hands have deformable fingertip pads [1, 2]. Deformable pads have the advantage of conforming to the objects that are being touched, ensuring a stable grasp for a large range of forces and shapes. Pad deformations change with finger displacements during touch. Pushing a finger against an external surface typically provokes an increase of the gross contact area [3], potentially providing a relative motion cue, a situation comparable to looming in vision [4]. The rate of increase of the area of contact also depends on the compliance of the object [5]. Because objects normally do not suddenly change compliance, participants may interpret an artificially induced variation in compliance, which coincides with a change in the gross contact area, as a change in finger displacement, and consequently they may misestimate their finger's position relative to the touched object. To test this, we asked participants to compare the perceived displacements of their finger while contacting an object varying pseudo-randomly in compliance from trial to trial. Results indicate a bias in the perception of finger displacement induced by the change in compliance, hence in contact area, indicating that participants interpreted the altered cutaneous input as a cue to proprioception. This situation highlights the capacity of the brain to take advantage of knowledge of the mechanical properties of the body and of the external environment. PMID:27068417

  13. A review of the potential and actual sources of pollution to groundwater in selected karst areas in Slovenia

    NASA Astrophysics Data System (ADS)

    Kovačič, G.; Ravbar, N.

    2005-02-01

    Slovenian karst areas extend over 43% of the country; limestones and dolomites of the Mesozoic era prevail. In Slovenia karst groundwater contributes up to 50% of the total drinking water supply. The quality of water is very high, despite the fact that it is extremely vulnerable to pollution. The present article is a study and a review of the potential and actual sources of pollution to the groundwater in the selected karst aquifers (the Kras, Velika planina and Snežnik plateaus), which differ in their natural characteristics. Unlike the other selected plateaus, the Kras plateau is inhabited. There are several settlements in the area and the industrial, agricultural and traffic activities carried out that represent a serious threat to the quality of karst groundwater. The Velika planina and Snežnik plateaus do not have permanent residents, however there are some serious hazards to the quality of the karst springs arising from sports, tourist, construction and farming activities, as well as from the traffic related to them. Despite relatively favourable conditions for protection, many important karst aquifers and springs are improperly protected in Slovenia. The reason is the lack of knowledge about sustainable water management in karst regions and the confusion in drinking water protection policy.

  14. A critical analysis of three remote sensing-based actual evapotranspiration assessment methods over sparse crops agricultural areas

    NASA Astrophysics Data System (ADS)

    Cammalleri, Carmelo; Ciraolo, Giuseppe; La Loggia, Goffredo; Minacapilli, Mario

    2010-10-01

    During last two decades the increasing availability of remotely sensed acquisitions in the thermal infrared part of the spectrum has encouraged hydrologist community to develop models and methodologies based on these kind of data. The aim of this paper is to compare three methods developed to assess the actual evapotranspiration spatial distribution by means of remote sensing data. The comparison was focused on the differences between the "single" (SEBAL) and "two" source (TSEB) surface energy balance approaches and the S-SEBI semi-empirical method. The first assumes a semiempirical internal calibration for the sensible heat flux assessment; the second uses a physically based approach in order to assess separately the soil and vegetation fluxes. Finally, the last one is based on the correlation between albedo and surface temperature for evaporative fraction estimations. The models were applied using 7 high resolution images, collected by an airborne platform between June and October 2008, approximately every 3 weeks. The acquired data include multi-spectral images (red, green and near infrared) and thermal infrared images for surface temperature estimation. The study area, located in the south-west cost of Sicily, Italy), is characterised by the presence of typical Mediterranean cultivations: olive, vineyard and citrus. Due to irrigation supplies and rainfall events, the water availability for the crops varies in time and this allowed to perform the comparison in a wide range of the modelled variables. Additionally, the availability of high spatial resolution images allowed the testing of the models performances at field scale despite the high vegetation fragmentation of the study area. The comparison of models performance highlights a good agreements of model estimations, analyzed by means of MAD (Mean Absolute Differences) and MAPD (Mean Absolute Percent Differences) indices, especially in terms of study area averaged fluxes. The analysis in correspondence of

  15. Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses.

    PubMed

    Witt, Florian; Gührs, Julian; Morlock, Michael M; Bishop, Nicholas E

    2015-01-01

    Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface. PMID:26280914

  16. Quantification of the Contact Area at the Head-Stem Taper Interface of Modular Hip Prostheses

    PubMed Central

    Witt, Florian; Gührs, Julian; Morlock, Michael M.; Bishop, Nicholas E.

    2015-01-01

    Corrosion of modular taper junctions of hip implants may be associated with clinical failure. Taper design parameters, as well as the intraoperatively applied assembly forces, have been proposed to affect corrosion. Fretting corrosion is related to relative interface shear motion and fluid ingress, which may vary with contact force and area. It was hypothesised in this study that assembly forces modify the extent and distribution of the surface contact area at the taper interface between a cobalt chrome head and titanium stem taper with a standard threaded surface profile. Local abrasion of a thin gold coating applied to the stem taper prior to assembly was used to determine the contact area after disassembly. Profilometry was then used to assess permanent deformation of the stem taper surface profile. With increasing assembly force (500 N, 2000 N, 4000 N and 8000 N) the number of stem taper surface profile ridges in contact with the head taper was found to increase (9.2±9.3%, 65.4±10.8%, 92.8±6.0% and 100%) and the overall taper area in contact was also found to increase (0.6±0.7%, 5.5±1.0%, 9.9±1.1% and 16.1±0.9%). Contact was inconsistently distributed over the length of the taper. An increase in plastic radial deformation of the surface ridges (-0.05±0.14 μm, 0.1±0.14 μm, 0.21±0.22 μm and 0.96±0.25 μm) was also observed with increasing assembly force. The limited contact of the taper surface ridges at lower assembly forces may influence corrosion rates, suggesting that the magnitude of the assembly force may affect clinical outcome. The method presented provides a simple and practical assessment of the contact area at the taper interface. PMID:26280914

  17. In situ observation of the molecular ordering in the lubricating point contact area

    NASA Astrophysics Data System (ADS)

    Zhang, Shaohua; Liu, Yuhong; Luo, Jianbin

    2014-07-01

    The organization of lubricant molecules confined between two solid surfaces when the lubricant film thickness is at the nanoscale is unknown. In this work, an ordering process of nematic liquid crystal molecules is observed by in situ polarized Raman spectroscopy of the lubricated point contact area. Our experimental results indicate that 4-n-pentyl-4'-cyanobiphenyl liquid crystal molecules orient along the rotation direction when the linear speed exceeds 12.6 mm/s, and the degree of order increases with linear speed. The relationship between the observed orientation and physical properties of the lubricant film is investigated. Isotropic orientation is observed at the outlet area of the contact region. The orientation behavior of liquid crystal molecules in a confined area is observed and the relationship between lubrication conditions and molecular orientation is discussed.

  18. Axoglial contacts in the area postrema of the cat - An ultrastructural study

    NASA Technical Reports Server (NTRS)

    Damelio, Fernando E.; Gibbs, Michael A.; Mehler, William R.; Philpott, Delbert E.; Savage, Wayne

    1986-01-01

    Axoglial contacts were observed in an ultrastructural study of the area postrema of the cat. According to the disposition of the electron-dense projections attached to the adjoining membranes these contacts were classified as symmetrical or asymmetrical. The axon profiles contained aggregations of clear vesicles randomly distributed or grouped in clusters adjacent to the electron-dense projections. Dense core vesicles were occasionally seen. The neuroglial profiles were either astrocytic or ependymoglial in nature. The astrocytes showed a clear cytoplasm, polymorphous vesicles, mitochondria, glycogen granules, and bundles of filaments. The ependymal cells, in contrast, had a more electron-dense and granular appearance, tubular structures, irregular vesicular formations, profiles of smooth reticuloendoplasm, and filaments grouped in bundles or isolated in the cytoplasm. The possibility that these contacts might play a role in the chemical transfer from neurons to glial cells is discussed on the basis of existing biochemical data.

  19. Compression and contact area of anterior strut grafts in spinal instrumentation: a biomechanical study

    PubMed Central

    2013-01-01

    Background Anterior bone grafts are used as struts to reconstruct the anterior column of the spine in kyphosis or following injury. An incomplete fusion can lead to later correction losses and compromise further healing. Despite the different stabilizing techniques that have evolved, from posterior or anterior fixating implants to combined anterior/posterior instrumentation, graft pseudarthrosis rates remain an important concern. Furthermore, the need for additional anterior implant fixation is still controversial. In this bench-top study, we focused on the graft-bone interface under various conditions, using two simulated spinal injury models and common surgical fixation techniques to investigate the effect of implant-mediated compression and contact on the anterior graft. Methods Calf spines were stabilised with posterior internal fixators. The wooden blocks as substitutes for strut grafts were impacted using a “pressfit” technique and pressure-sensitive films placed at the interface between the vertebral bone and the graft to record the compression force and the contact area with various stabilization techniques. Compression was achieved either with posterior internal fixator alone or with an additional anterior implant. The importance of concomitant ligament damage was also considered using two simulated injury models: pure compression Magerl/AO fracture type A or rotation/translation fracture type C models. Results In type A injury models, 1 mm-oversized grafts for impaction grafting provided good compression and fair contact areas that were both markedly increased by the use of additional compressing anterior rods or by shortening the posterior fixator construct. Anterior instrumentation by itself had similar effects. For type C injuries, dramatic differences were observed between the techniques, as there was a net decrease in compression and an inadequate contact on the graft occurred in this model. Under these circumstances, both compression and the

  20. AFM-based tribological study of nanopatterned surfaces: the influence of contact area instabilities.

    PubMed

    Rota, A; Serpini, E; Gazzadi, G C; Valeri, S

    2016-04-01

    Although the importance of morphology on the tribological properties of surfaces has long been proved, an exhaustive understanding of nanopatterning effects is still lacking due to the difficulty in both fabricating 'really nano-' structures and detecting their tribological properties. In the present work we show how the probe-surface contact area can be a critical parameter due to its remarkable local variability, making a correct interpretation of the data very difficult in the case of extremely small nanofeatures. Regular arrays of parallel 1D straight nanoprotrusions were fabricated by means of a low-dose focused ion beam, taking advantage of the amorphization-related swelling effect. The tribological properties of the patterns were detected in the presence of air and in vacuum (dry ambient) by atomic force microscopy. We have introduced a novel procedure and data analysis to reduce the uncertainties related to contact instabilities. The real time estimation of the radius of curvature of the contacting asperity enables us to study the dependence of the tribological properties of the patterns from their geometrical characteristics. The effect of the patterns on both adhesion and the coefficient of friction strongly depends on the contact area, which is linked to the local radius of curvature of the probe. However, a detectable hydrophobic character induced on the hydrophilic native SiO2 has been observed as well. The results suggest a scenario for capillary formation on the patterns. PMID:26934217

  1. AFM-based tribological study of nanopatterned surfaces: the influence of contact area instabilities

    NASA Astrophysics Data System (ADS)

    Rota, A.; Serpini, E.; Gazzadi, G. C.; Valeri, S.

    2016-04-01

    Although the importance of morphology on the tribological properties of surfaces has long been proved, an exhaustive understanding of nanopatterning effects is still lacking due to the difficulty in both fabricating ‘really nano-’ structures and detecting their tribological properties. In the present work we show how the probe-surface contact area can be a critical parameter due to its remarkable local variability, making a correct interpretation of the data very difficult in the case of extremely small nanofeatures. Regular arrays of parallel 1D straight nanoprotrusions were fabricated by means of a low-dose focused ion beam, taking advantage of the amorphization-related swelling effect. The tribological properties of the patterns were detected in the presence of air and in vacuum (dry ambient) by atomic force microscopy. We have introduced a novel procedure and data analysis to reduce the uncertainties related to contact instabilities. The real time estimation of the radius of curvature of the contacting asperity enables us to study the dependence of the tribological properties of the patterns from their geometrical characteristics. The effect of the patterns on both adhesion and the coefficient of friction strongly depends on the contact area, which is linked to the local radius of curvature of the probe. However, a detectable hydrophobic character induced on the hydrophilic native SiO2 has been observed as well. The results suggest a scenario for capillary formation on the patterns.

  2. The Effect of Contact Area on the Fluid Flow-Fracture Specific Stiffness Relationship

    NASA Astrophysics Data System (ADS)

    Petrovitch, C.; Pyrak-Nolte, L. J.; Nolte, D. D.

    2009-12-01

    The integrity of subsurface CO2 sequestration sites can be compromised by the presence of mechanical discontinuities such as fractures, joints and faults. The ability to detect, seismically, and determine whether a discontinuity poses a risk, requires an understanding of the interrelationships among the mechanical, hydraulic and seismic properties of fractures rock. We performed a computational study to investigate the effect of fracture geometry on the relationship between fluid flow and fracture specific stiffness. The form of this relationship and the ability to scale it among different sample sizes provides a key link between the hydraulic and seismic response of fractures. In this study, model fracture topologies were simulated using the stratified continuum percolation method. This method constructs a hierarchical aperture distribution with a tunable spatial correlation length. Fractures with correlated and uncorrelated aperture distributions were used. The contact area across the fracture plane ranged from approximately 5% to 40%. The fracture specific stiffness was calculated by deforming each fracture numerically under a normal load and extracting the stiffness from the displacement-stress curves. Single-phase flow was calculated for each increment of stress by modeling the fracture topology as a network of elliptical pipes and solving the corresponding linear system of equations. We analyzed the relationship between fracture displacement and contact area and found that the correlation length associated with the contact area distribution enables a scaling relationship between displacement and contact area. The collapse of the fluid flow - stress relationship required use of standard percolation functional forms that use average aperture (cubic law), the void area fraction, and the correlation length of the contact area clusters. A final scaling relationship between fluid flow and fracture specific was found for the class of correlated fractures while a

  3. Modulation of contact resistance between metal and graphene by controlling the graphene edge, contact area, and point defects: An ab initio study

    SciTech Connect

    Ma, Bo; Wen, Yanwei E-mail: bshan@mail.hust.edu.cn; Gong, Cheng; Cho, Kyeongjae; Chen, Rong; Shan, Bin E-mail: bshan@mail.hust.edu.cn

    2014-05-14

    A systematic first-principles non-equilibrium Green's function study is conducted on the contact resistance between a series of metals (Au, Ag, Pt, Cu, Ni, and Pd) and graphene in the side contact geometry. Different factors such as the termination of the graphene edge, contact area, and point defect in contacted graphene are investigated. Notable differences are observed in structural configurations and electronic transport characteristics of these metal-graphene contacts, depending on the metal species and aforementioned influencing factors. It is found that the enhanced chemical reactivity of the graphene due to dangling bonds from either the unsaturated graphene edge or point defects strengthens the metal-graphene bonding, leading to a considerable contact resistance reduction for weakly interacting metals Au and Ag. For stronger interacting metals Pt and Cu, a slightly reduced contact resistance is found due to such influencing factors. However, the wetting metals Ni and Pd most strongly hybridize with graphene, exhibiting negligible dependence on the above influencing factors. This study provides guidance for the optimization of metal-graphene contacts at an atomic scale.

  4. Plasma Treatment of Ciir Rubber with Improvement of Adhesion and Real Contact Area

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Hyoung; Nitta, Isami; Umehara, Noritsugu; Kousaka, Hiroyuki; Shimada, Mamoru; Hasegawa, Mitsuru

    The adhesion force between a chloride-isobutene-isoprene rubber (CIIR) and stainless steel ball was studied. To decrease the adhesion force, the CIIR rubber was treated with high-density microwave plasma employing oxygen and argon gases. The experimental results showed that the adhesion force decreases with increasing the time of oxygen and argon plasma treatments. In addition, the contact microscope measurements revealed different surface structure with two gases. The real contact area also decreased with treatment time and dramatic changes were observed after 5 min treatment of CIIR rubber. The field emission scanning electron microscope image also showed that the subsurface of CIIR rubber pattern has changed with various plasma treatments. These results imply change in the morphology of CIIR rubber surface by plasma treatment is one reason for the decrease in adhesion forces.

  5. Vibrotactile difference thresholds: effects of vibration frequency, vibration magnitude, contact area, and body location.

    PubMed

    Forta, Nazim Gizem; Griffin, Michael J; Morioka, Miyuki

    2012-01-01

    It has not been established whether the smallest perceptible change in the intensity of vibrotactile stimuli depends on the somatosensory channel mediating the sensation. This study investigated intensity difference thresholds for vibration using contact conditions (different frequencies, magnitudes, contact areas, body locations) selected so that perception would be mediated by more than one psychophysical channel. It was hypothesized that difference thresholds mediated by the non-Pacinian I (NPI) channel and the Pacinian (P) channel would differ. Using two different contactors (1-mm diameter contactor with 1-mm gap to a fixed surround; 10-mm diameter contactor with 2-mm gap to the surround) vibration was applied to the thenar eminence and the volar forearm at two frequencies (10 and 125 Hz). The up-down-transformed-response method with a three-down-one-up rule provided absolute thresholds and also difference thresholds at various levels above the absolute thresholds of 12 subjects (i.e., sensation levels, SLs) selected to activate preferentially either single channels or multiple channels. Median difference thresholds varied from 0.20 (thenar eminence with 125-Hz vibration at 10 dB SL) to 0.58 (thenar eminence with 10-Hz vibration at 20 dB SL). Median difference thresholds tended to be lower for the P channel than the NPI channel. The NPII channel may have reduced difference thresholds with the smaller contactor at 125 Hz. It is concluded that there are large and systematic variations in difference thresholds associated with the frequency, the magnitude, the area of contact, and the location of contact with vibrotactile stimuli that cannot be explained without increased understanding of the perception of supra-threshold vibrotactile stimuli. PMID:22416802

  6. Mapping the Articular Contact Area of the Long Head of the Biceps Tendon on the Humeral Head

    PubMed Central

    Morris, Brent J.; Byram, Ian R.; Lathrop, Ray A.; Dunn, Warren R.; Kuhn, John E.

    2014-01-01

    The purpose of this investigation was to calculate the contact surface area of the long head of the biceps (LHB) in neutral position and abduction. We sought to determine whether the LHB articulates with the humeral head in a consistent pattern comparing articular contact area in neutral position and abduction. Eleven fresh frozen matched cadaveric shoulders were analyzed. The path of the biceps tendon on the articular surface of the humeral head and the total articular surface were digitized using a MicronTracker 2 H3-60 three-dimensional optical tracker. Contact surface area was significantly less in abduction than in neutral position (P = 0.002) with a median ratio of 41% (36%, 47.5%). Ratios of contact area in neutral position to full articular surface area were consistent between left and right shoulders (rho = 1, P = 0.017) as were ratios of abduction area to full articular surface area (rho = 0.97, P = 0.005). The articular contact surface area is significantly greater in neutral position than abduction. The ratios of articular contact surface areas to total humeral articular surface areas have a narrow range and are consistent between left and right shoulders of the same cadaver. PMID:25210631

  7. Investigation of welded interconnection of large area wraparound contacted silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lott, D. R.

    1984-01-01

    An investigation was conducted to evaluate the welding and temperature cycle testing of large area 5.9 x 5.9 wraparound silicon solar cells utilizing printed circuit substrates with SSC-155 interconnect copper metals and the LMSC Infrared Controlled weld station. An initial group of 5 welded modules containing Phase 2 developmental 5.9 x 5.9 cm cells were subjected to cyclical temperatures of + or 80 C at a rate of 120 cycles per day. Anomalies were noted in the adhesion of the cell contact metallization; therefore, 5 additional modules were fabricated and tested using available Phase I cells with demonstrated contact integrity. Cycling of the later module type through 12,000 cycles indicated the viability of this type of lightweight flexible array concept. This project demonstrated acceptable use of an alternate interconnect copper in combination with large area wraparound cells and emphasized the necessity to implement weld pull as opposed to solder pull procedures at the cell vendors for cells that will be interconnected by welding.

  8. Identification and tabulation of geological contacts in the Edwards Aquifer, San Antonio area, Texas

    USGS Publications Warehouse

    Small, Ted A.

    1984-01-01

    Other important formation contacts identified were the Austin Group, the Eagle Ford Group, the Buda Limestone, and the Glen Rose Formation. These contacts were usually easy to identify on either gamma-ray or electric logs.

  9. 2-D discrete element modeling of the fault zone considering the time-dependent increase of contact area

    NASA Astrophysics Data System (ADS)

    Igami, M.; Shibazaki, B.; Nakama, Y.

    2002-12-01

    Particle based simulations such as the lattice solid modeling (Mora and Place, 1994; Abe et al., 2002) and the modeling using the discrete element method (Morgan and Boettcher, 1999) are very useful for investigating frictional behavior of the fault zone. We investigate the fault behavior using the discrete element method considering the effect of the time-dependent increase of contact area between particles. In our model the tangential force due to the frictional contact is assumed to be SA, where S is the shear stress within microcontacts and A is the contact area. For stationary contact, the contact area is assumed to increase with time following the equation A(t)=A0}(1+k{BT/E ln (1+t/t0)) (Brechet and Estrin, 1994), where t0 is an increasing function of temperature T. On the other hand, when sliding velocity V is not equal to 0, t is replaced with D c/V. Based on the elastic contact theory, A0 is assumed to be in proportion to Fn3/2, where Fn is the normal force that acts on each grain. As a test, we perform velocity step experiments. We consider the particle size distribution of r max/r min=2, where r max and r min represent maximum and minimum particle size, respectively. We found that stability of the fault zone is controlled by T. For small T or t0, velocity weakening behavior was observed. When T or t0 is large, however, no velocity weakening was observed. Our model is able to include the increase of contact area due to solution-transfer proposed by Hickman and Evans (1992). We also report the results of numerical simulation using the functional form of contact area when the solution-transfer is at work within microcontacts.

  10. The fraction of total hand surface area involved in young children's outdoor hand-to-object contacts

    SciTech Connect

    AuYeung, Willa; Canales, Robert A. Leckie, James O.

    2008-11-15

    Information on the fraction of total hand surface area touching a contaminated object is necessary in accurately estimating contaminant (e.g., pesticides, pathogens) loadings onto the hands during hand-to-object contacts. While several existing physical-stochastic human exposure models require such surface area data to estimate dermal and non-dietary ingestion exposure, there are very limited data sets. This paper provides statistical distributions of fractional surface areas (FSAs) for children's outdoor hand contacts. These distributions were constructed by combining information collected from two distinct studies exploring children's activity patterns and quantifying hand contact surface area. Results show that for outdoor contacts with 'All Objects', a range of 0.13-0.27 captured median FSAs, while a range of 0.12-0.24 captured time-weighted FSAs. Overall, an FSA of 0.31 captured 80-100% of FSAs involved in each child's outdoor hand contacts, depending upon the object of interest. These values are much lower than the often conservative assumptions of up to 1 (i.e., the entire hand) that researchers currently make regarding FSAs involved in indoor and outdoor contacts [USEPA, 1997. Standard operating procedures (SOPs) for residential exposure assessments. Contract no. 68-W6-0030. < (http://www.epa.gov/pesticides/trac/science/trac6a05.pdf)>].

  11. Large area, low cost space solar cells with optional wraparound contacts

    NASA Technical Reports Server (NTRS)

    Michaels, D.; Mendoza, N.; Williams, R.

    1981-01-01

    Design parameters for two large area, low cost solar cells are presented, and electron irradiation testing, thermal alpha testing, and cell processing are discussed. The devices are a 2 ohm-cm base resistivity silicon cell with an evaporated aluminum reflector produced in a dielectric wraparound cell, and a 10 ohm-cm silicon cell with the BSF/BSR combination and a conventional contact system. Both cells are 5.9 x 5.9 cm and require 200 micron thick silicon material due to mission weight constraints. Normalized values for open circuit voltage, short circuit current, and maximum power calculations derived from electron radiation testing are given. In addition, thermal alpha testing values of absorptivity and emittance are included. A pilot cell processing run produced cells averaging 14.4% efficiencies at AMO 28 C. Manufacturing for such cells will be on a mechanized process line, and the area of coverslide application technology must be considered in order to achieve cost effective production.

  12. A measurement method for distinguishing the real contact area of rough surfaces of transparent solids using improved Otsu technique

    NASA Astrophysics Data System (ADS)

    Song, Bao-Jiang; Yan, Shao-Ze; Xiang, Wu-Wei-Kai

    2015-01-01

    An experimental method of measuring the real contact area of transparent blocks based on the principle of total internal reflection is presented, intending to support the investigation of friction characteristics, heat conduction, and energy dissipation at the contact interface. A laser sheet illuminates the contact interface, and the transmitted laser sheet is projected onto a screen. Then the contact information is acquired from the screen by a camera. An improved Otsu method is proposed to process the data of experimental images. It can compute the threshold of the overall image and filter out all the pixels one by one. Through analyzing the experimental results, we describe the relationship between the real contact area and the positive pressure during a continuous loading process, at different loading rates, with the polymethyl methacrylate (PMMA) material. A hysteresis phenomenon in the relationship between the real contact area and the positive pressure is found and explained. Project supported by the National Natural Science Foundation of China (Grant No. 11272171), the Beijing Natural Science Foundation, China (Grant No. 3132030), and the Education Ministry Doctoral Fund of China (Grant No. 20120002110070).

  13. Dynamics of spider glue adhesion: effect of surface energy and contact area

    NASA Astrophysics Data System (ADS)

    Amarpuri, Gaurav; Chen, Yizhou; Blackledge, Todd; Dhinojwala, Ali

    Spider glue is a unique biological adhesive which is humidity responsive such that the adhesion continues to increase upto 100% relative humidity (RH) for some species. This is unlike synthetic adhesives that significantly drop in adhesion with an increase in humidity. However, most of adhesion data reported in literature have used clean hydrophilic glass substrate, unlike the hydrophobic, and charged insect cuticle surface that adheres to spider glue in nature. Previously, we have reported that the spider glue viscosity changes over five orders of magnitude with humidity. Here, we vary the surface energy and surface charge of the substrate to test the change in Larnioides cornutus spider glue adhesion with humidity. We find that an increase in both surface energy and surface charge density increases the droplet spreading and there exists an optimum droplet contact area where adhesion is maximized. Moreover, spider glue droplets act as reusable adhesive for low energy hydrophobic surface at the optimum humidity. These results explain why certain prey are caught more efficiently by spiders in their habitat. The mechanism by which spider species tune its glue adhesion for local prey capture can inspire new generation smart adhesives.

  14. Farmer Contacts with District Agriculturists in Three Areas in British Columbia.

    ERIC Educational Resources Information Center

    Akinbode, Isaac A.; Dorling, M. J.

    This study analyzed data gathered in a Canada Land Inventory project in British Columbia; the purpose was to measure the degree of communication between farmers and the agricultural extension service by analyzing the nature and extent of contacts, and the relationship of the contacts to socioeconomic characteristics. The farmers tended to be an…

  15. Effect on signal-to-noise ratio of splitting the continuous contacts of cuff electrodes into smaller recording areas

    PubMed Central

    2013-01-01

    Background Cuff electrodes have been widely used chronically in different clinical applications. This neural interface has been dominantly used for nerve stimulation while interfering noise is the major issue when employed for recording purposes. Advancements have been made in rejecting extra-neural interference by using continuous ring contacts in tripolar topologies. Ring contacts provide an average of the neural activity, and thus reduce the information retrieved. Splitting these contacts into smaller recording areas could potentially increase the information content. In this study, we investigate the impact of such discretization on the Signal-to-Noise Ratio (SNR). The effect of contacts positioning and an additional short circuited pair of electrodes were also addressed. Methods Different recording configurations using ring, dot, and a mixed of both contacts were studied in vitro in a frog model. An interfering signal was induced in the medium to simulate myoelectric noise. The experimental setup was design in such a way that the only difference between recordings was the configuration used. The inter-session experimental differences were taken care of by a common configuration that allowed normalization between electrode designs. Results It was found that splitting all contacts into small recording areas had negative effects on noise rejection. However, if this is only applied to the central contact creating a mixed tripole configuration, a considerable and statistically significant improvement was observed. Moreover, the signal to noise ratio was equal or larger than what can be achieved with the best known configuration, namely the short circuited tripole. This suggests that for recording purposes, any tripole topology would benefit from splitting the central contact into one or more discrete contacts. Conclusions Our results showed that a mixed tripole configuration performs better than the configuration including only ring contacts. Therefore, splitting

  16. The effect of axial force and contact angle on the welded area of plastic tube welded by ultrasonic welding

    NASA Astrophysics Data System (ADS)

    Thinvongpituk, C.; Bootwong, A.; Watanabe, Y.

    2010-03-01

    This study was aimed to apply the use of ultrasonic welding to weld round plastic tubes. The ultrasonic welding machine was designed to be able to work with a normal ultrasonic welding transducer by rotating the tube while it is being welded. The specimens used in this study were round plastic tubes (PMMA) with diameter of 35 mm and 2 mm thickness. End of each tube was machined to have angle of 2.8, 3.8 and 5.7 degree in order to create contact angle at the interface. The specimens were welded with frequency of 28 kHz and tube rotational speeds of 25 rpm, 45 rpm and 100 rpm. The axial force was applied to the tube in order to enhance the quality of joint. The experimental result revealed that the modified ultrasonic welding machine can generate the welded area around the circumference of tube. It was found that the axial force and contact angle have some effect to the quality of joint. The contact angle of 2.8/2.8 provided highest welded area compared to 3.8/3.8 and 5.7/5.7 degree of contact angle. In addition, the axial force between 80 N - 120 N provided high value of welded area. The pattern of welded area is also presented and discussed in the paper.

  17. The effect of axial force and contact angle on the welded area of plastic tube welded by ultrasonic welding

    NASA Astrophysics Data System (ADS)

    Thinvongpituk, C.; Bootwong, A.; Watanabe, Y.

    2009-12-01

    This study was aimed to apply the use of ultrasonic welding to weld round plastic tubes. The ultrasonic welding machine was designed to be able to work with a normal ultrasonic welding transducer by rotating the tube while it is being welded. The specimens used in this study were round plastic tubes (PMMA) with diameter of 35 mm and 2 mm thickness. End of each tube was machined to have angle of 2.8, 3.8 and 5.7 degree in order to create contact angle at the interface. The specimens were welded with frequency of 28 kHz and tube rotational speeds of 25 rpm, 45 rpm and 100 rpm. The axial force was applied to the tube in order to enhance the quality of joint. The experimental result revealed that the modified ultrasonic welding machine can generate the welded area around the circumference of tube. It was found that the axial force and contact angle have some effect to the quality of joint. The contact angle of 2.8/2.8 provided highest welded area compared to 3.8/3.8 and 5.7/5.7 degree of contact angle. In addition, the axial force between 80 N - 120 N provided high value of welded area. The pattern of welded area is also presented and discussed in the paper.

  18. An examination of the interparticle contact area during sintering of W-0.3 wt pct Co

    SciTech Connect

    Mitlin, D.; German, R.M.

    1998-04-01

    As a powder compact sinters, its microstructure evolves. One way to quantify the scale of the microstructure is to consider the interparticle contact area. This study examines two known models for calculating the interparticle contact area: the classic two-sphere model and the Voronoi cell model. Both models have particular assumptions about the microstructure that make them not applicable for treating densification to near full density with concurrent grain growth. The classic two-sphere model assumes a regular packing of particles and a perfectly spherical particle geometry and neglects an increasing particle coordination number with sintering. The Voronoi cell model assumes that the scale of the microstructure remains constant; i.e., as long as the compact is densifying, grain growth does not occur. The authors propose a modified Voronoi cell that accounts for an increasing grain size, making it applicable to a general case where grain growth occurs during sintering. The three models are compared to the interparticle contact area data, obtained by stereology techniques, for W-0.3 wt pct Co sintered from green state to near full density. The original Voronoi cell model fits the data only at low temperatures, before the onset of grain growth. Below approximately 90 pct relative density, the two-sphere model with an assumed coordination number of six (coordination number in a green compact) and the modified Voronoi cell model provide a good fit to the data. At higher densities, both models overestimate the interparticle contact area.

  19. Urban thermal environment measurements and numerical simulation for an actual complex urban area covering a large district heating and cooling system in summer

    NASA Astrophysics Data System (ADS)

    Huang, Hong; Ooka, Ryozo; Kato, Shinsuke

    Urban thermal situation is thought to have a great influence on the air quality in urban areas. In recent years, the urban thermal environment has become worse, such as the days on which the temperature goes above 30 °C, the sultry nights and heat stroke increase due to changes in terrestrial cover and increased anthropogenic heat emission accompanied by urbanization. Therefore, the urban thermal environment should be carefully investigated and accurately analyzed for a better study of the air quality. Here, in order to study the urban thermal environment in summer, (1) the actual status of an urban thermal environment in a complex urban area covering a large district heating and cooling (DHC) system in Tokyo is investigated using field measurements, and (2) a numerical simulation program which can be adapted to complex urban areas coupled with convection, radiation and conduction is developed and used to predict the urban thermal environment. Wind velocity, temperature and humidity are obtained from the simulation, which shows good agreement with results of the field measurement. The spatial distribution of the standard effective temperature (SET *), the comprehensive index of human thermal comfort, is also calculated using the above results, to estimate the thermal comfort at the pedestrian level. This urban thermal numerical simulation can be coupled with air pollution dispersion and chemical processes to provide a more precise air quality prediction in complex urban areas.

  20. Induction of Electrode-Cellular Interfaces with ˜ 0.05 μm^2 Contact Areas

    NASA Astrophysics Data System (ADS)

    Flanders, Bret; Thapa, Prem

    2009-10-01

    Individual cells of the slime mold Dictyostelium discoideum attach themselves to negatively biased nanoelectrodes that are separated by 30 μm from grounded electrodes. There is a -43 mV voltage-threshold for cell-to-electrode attachment, with negligible probability across the 0 to -38 mV range but probability that approaches 0.7 across the -46 to -100 mV range. A cell initiates contact by extending a pseudopod to the electrode and maintains contact until the voltage is turned off. Scanning electron micrographs of these interfaces show the contact areas to be of the order of 0.05 μm^2. Insight into this straight-forward, reproducible process may lead to new electrode-cellular attachment strategies that complement established approaches, such as blind sampling and patch clamp.

  1. Defining the value of injection current and effective electrical contact area for EGaIn-based molecular tunneling junctions.

    PubMed

    Simeone, Felice C; Yoon, Hyo Jae; Thuo, Martin M; Barber, Jabulani R; Smith, Barbara; Whitesides, George M

    2013-12-01

    Analysis of rates of tunneling across self-assembled monolayers (SAMs) of n-alkanethiolates SCn (with n = number of carbon atoms) incorporated in junctions having structure Ag(TS)-SAM//Ga2O3/EGaIn leads to a value for the injection tunnel current density J0 (i.e., the current flowing through an ideal junction with n = 0) of 10(3.6±0.3) A·cm(-2) (V = +0.5 V). This estimation of J0 does not involve an extrapolation in length, because it was possible to measure current densities across SAMs over the range of lengths n = 1-18. This value of J0 is estimated under the assumption that values of the geometrical contact area equal the values of the effective electrical contact area. Detailed experimental analysis, however, indicates that the roughness of the Ga2O3 layer, and that of the Ag(TS)-SAM, determine values of the effective electrical contact area that are ~10(-4) the corresponding values of the geometrical contact area. Conversion of the values of geometrical contact area into the corresponding values of effective electrical contact area results in J0(+0.5 V) = 10(7.6±0.8) A·cm(-2), which is compatible with values reported for junctions using top-electrodes of evaporated Au, and graphene, and also comparable with values of J0 estimated from tunneling through single molecules. For these EGaIn-based junctions, the value of the tunneling decay factor β (β = 0.75 ± 0.02 Å(-1); β = 0.92 ± 0.02 nC(-1)) falls within the consensus range across different types of junctions (β = 0.73-0.89 Å(-1); β = 0.9-1.1 nC(-1)). A comparison of the characteristics of conical Ga2O3/EGaIn tips with the characteristics of other top-electrodes suggests that the EGaIn-based electrodes provide a particularly attractive technology for physical-organic studies of charge transport across SAMs. PMID:24187999

  2. Frequency of standard and occupational contact allergens in Tuzla area, Bosnia and Herzegovina: retrospective study.

    PubMed

    Sijercić, Nerma; Hadzigrahić, Nermina; Kamberović, Selma; Suljagić, Edin

    2003-01-01

    Allergic contact dermatitis is acute or chronic inflammatory skin disease of allergic etiology, which develops as a result of delayed type of hypersensitivity, i.e. type IV reaction according to the Gell and Coombs classification. In the retrospective study, we reviewed medical records of 495 patients diagnosed with allergic contact dermatitis in the 1988-1998 period. The records were obtained from the Cabinet of Allergology of the Department of Dermatology and Venerology, Tuzla University Hospital Center. There were 312 women and 183 men, aged between 18 and 60 years. The patients were divided into 6 groups according to their occupation. Contact sensitization was established in 295 or 59.6% of them. The type and frequency of causative agent in allergic contact dermatitis depended on working environment. Potassium dichromate, a component part of cement, caused positive reaction in 48% of construction workers tested, which was significantly more than in the "other occupation" group, where 14.6% of patients showed positive reaction to potassium dichromate (p<0.001). Formaldehyde, used in leather processing, was the most frequent among the four leading allergens in the group of shoe workers (13.3%), whereas charcoal tar (used in the metal processing) was the most frequent allergen in the group of metal workers (13.9%). Nickel sulfate, potassium dichromate, cobalt chloride, and urushiol were frequent allergens in the "other occupation" group, housewives, and textile workers. The listed allergens are present at large in everyday life as well as in particular occupations. PMID:12773263

  3. Winton Contact Teacher Centre Report. Priority Country Area Program, Queensland Project Report 2.

    ERIC Educational Resources Information Center

    Saide, Tom

    The experimental Contact Teacher Centre at Winton State Primary School was established in March 1983 to expand the avenues of service delivery for 20 isolated Queensland primary school children from 14 families living within an 80 kilometer radius of Winton. The aims of the Centre were to: (1) assist correspondence pupils with their work; (2)…

  4. Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

    SciTech Connect

    Shaforost, O.; Wang, K.; Adabi, M.; Guo, Z.; Hanham, S.; Klein, N.; Goniszewski, S.; Gallop, J.; Hao, L.

    2015-01-14

    A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples.

  5. Contact-free sheet resistance determination of large area graphene layers by an open dielectric loaded microwave cavity

    NASA Astrophysics Data System (ADS)

    Shaforost, O.; Wang, K.; Goniszewski, S.; Adabi, M.; Guo, Z.; Hanham, S.; Gallop, J.; Hao, L.; Klein, N.

    2015-01-01

    A method for contact-free determination of the sheet resistance of large-area and arbitrary shaped wafers or sheets coated with graphene and other (semi) conducting ultrathin layers is described, which is based on an open dielectric loaded microwave cavity. The sample under test is exposed to the evanescent resonant field outside the cavity. A comparison with a closed cavity configuration revealed that radiation losses have no significant influence of the experimental results. Moreover, the microwave sheet resistance results show good agreement with the dc conductivity determined by four-probe van der Pauw measurements on a set of CVD samples transferred on quartz. As an example of a practical application, correlations between the sheet resistance and deposition conditions for CVD graphene transferred on quartz wafers are described. Our method has a high potential as measurement standard for contact-free sheet resistance measurement and mapping of large area graphene samples.

  6. Electrical Properties of Synthesized Large-Area MoS₂ Field-Effect Transistors Fabricated with Inkjet-Printed Contacts.

    PubMed

    Kim, Tae-Young; Amani, Matin; Ahn, Geun Ho; Song, Younggul; Javey, Ali; Chung, Seungjun; Lee, Takhee

    2016-02-23

    We report the electrical properties of synthesized large-area monolayer molybdenum disulfide (MoS2) field-effect transistors (FETs) with low-cost inkjet-printed Ag electrodes. The monolayer MoS2 film was grown by a chemical vapor deposition (CVD) method, and the top-contact Ag source/drain electrodes (S/D) were deposited onto the films using a low-cost drop-on-demand inkjet-printing process without any masks and surface treatments. The electrical characteristics of FETs were comparable to those fabricated by conventional deposition methods such as photo- or electron beam lithography. The contact properties between the S/D and the semiconductor layer were also evaluated using the Y-function method and an analysis of the output characteristic at the low drain voltage regimes. Furthermore, the electrical instability under positive gate-bias stress was studied to investigate the charge-trapping mechanism of the FETs. CVD-grown large-area monolayer MoS2 FETs with inkjet-printed contacts may represent an attractive approach for realizing large-area and low-cost thin-film electronics. PMID:26820160

  7. Motile Human Neutrophils Sense Ligand Density Over Their Entire Contact Area.

    PubMed

    Henry, Steven J; Crocker, John C; Hammer, Daniel A

    2016-04-01

    Neutrophils are key components of the immune system and motility is central their function during the inflammatory response. We have previously demonstrated that neutrophils are capable of switching their motile phenotype between amoeboid-like and keratocyte-like in response to the ligand density of adhesion molecules (Henry et al. in Int Biol 6:348-356, 2014). In this study, we engineered planar micropatterned surfaces that presented adhesion molecules in local islands of high density, separated by regions largely devoid of ligands. By controlling the geometry of islands we made arrays in which the local (on island) adhesion density was high but the global (multi-island) adhesion density over the entire cell-substrate interface was low. Neutrophils in contact with these island arrays assumed a well-spread and directionally-persistent motile phenotype (keratocyte-like) in contrast to the classical amoeboid morphology they display on uniform fields of high adhesion density. By virtue of our rationally designed substrates, we were able to conclude that neutrophils were integrating the stimulation received across their entire contact interface; furthermore, they were able to mount this whole cell response on the timescale of seconds. This work demonstrates the capacity of adhesive microenvironments to direct the phenotype of cell motility, which has broader implications in physiologic processes such as inflammation and cancer metastasis. PMID:26219404

  8. Actual Condition of Paddy Field Levee Maintenance by Various Farm Households including Large-scale Farming in the Developed Land Renting Area

    NASA Astrophysics Data System (ADS)

    Sakata, Yasuyo

    The survey of interview, resource acquisition, photographic operation, and questionnaire were carried out in the “n” Community in the “y” District in Hakusan City in Ishikawa Prefecture to investigate the actual condition of paddy field levee maintenance in the area where land-renting market was proceeding, large-scale farming was dominant, and the problems of geographically scattered farm-land existed. In the study zone, 1) an agricultural production legal person rent-cultivated some of the paddy fields and maintained the levees, 2) another agricultural production legal person rent-cultivated some of the soy bean fields for crop changeover and land owners maintained the levees. The results indicated that sufficient maintenance was executed on the levees of the paddy fields cultivated by the agricultural production legal person, the soy bean fields for crop changeover, and the paddy fields cultivated by the land owners. Each reason is considered to be the managerial strategy, the economic incentive, the mutual monitoring and cross-regulatory mechanism, etc.

  9. Acanthamoeba spp. in domestic tap water in houses of contact lens wearers in the metropolitan area of Mexico City.

    PubMed

    Bonilla-Lemus, Patricia; Ramírez-Bautista, Gerardo A; Zamora-Muñoz, Claudia; Ibarra-Montes, María Del Rocío; Ramírez-Flores, Elizabeth; Hernández-Martínez, María Dolores

    2010-09-01

    A survey was carried out in the metropolitan area of Mexico City to determine the presence of Acanthamoeba in the tap water of houses of contact lens wearers. Water samples were taken from the mains water entry, bathroom sinks and storage containers (roof tanks, cisterns) of 27 houses; and from the solution contained in the contact lens cases. Samples were filtered and cultured onto NNE medium. The isolates were identified based on their morphological features and pathogenicity. Total and fecal coliforms, water temperature, pH, dissolved oxygen and residual free-chlorine were measured by standard methods. Forty five isolates of Acanthamoeba from 200 water samples were obtained. The highest number of amoebae was isolated from cisterns and roof tanks. Most Acanthamoeba isolates were non-pathogenic, however, their presence in tap water is a potential hazard since some species can cause Acanthamoeba keratitis and granulomatous amoebic encephalitis. PMID:19995560

  10. Reductions in finger blood flow induced by 125-Hz vibration: effect of area of contact with vibration.

    PubMed

    Ye, Ying; Griffin, Michael J

    2013-04-01

    To investigate whether the Pacinian channel is involved in vibration-induced reductions of finger blood flow (FBF), vibrotactile thresholds and vasoconstriction have been studied with 125-Hz vibration and two contact areas: 3- or 6-mm-diameter vibrating probes with 2-mm gaps to fixed surrounds. Fifteen subjects provided thresholds for perceiving vibration at the thenar eminence of the right hand with both contact areas. With both contact areas, FBF was then measured in the middle fingers of both hands during five successive 5-min periods: (i) no force and no vibration, (ii) force and no vibration, (iii) force with vibration 15 dB above threshold, (iv) force and no vibration, and (v) no force and no vibration. Thresholds were in the ranges of 0.16-0.66 ms(-2) r.m.s. (6-mm probe) and 0.32-1.62 ms(-2) r.m.s. (3-mm probe). With the magnitude of vibration 15 dB above each individual's threshold with the 3-mm probe, the median reduction in FBF with the 6-mm probe (to 70 and 77 % of pre-exposure FBF on the exposed right hand and the unexposed left hand, respectively) was greater than with the 3-mm probe (79 and 85 %). There were similar reductions in FBF when vibration was presented by the two contactors at the same sensation level (i.e. 15 dB above threshold with each probe). The findings are consistent with reductions in FBF arising from excitation of the Pacinian channel: increasing the area excited by vibration increases Pacinian activation and provokes stronger perception of vibration and greater vasoconstriction. PMID:23064872

  11. Enhanced wear and corrosion in modular tapers in total hip replacement is associated with the contact area and surface topography.

    PubMed

    Panagiotidou, Anna; Meswania, Jay; Hua, Jia; Muirhead-Allwood, Sarah; Hart, Alister; Blunn, Gordon

    2013-12-01

    Widespread concern exists about adverse tissue reactions after metal-on-metal (MoM) total hip replacement (THR). Concerns have also been expressed with wear and corrosion of taper junctions in THR. We report the effect of surface finish and contact area associated with a single combination of materials of modular tapers. In an in vitro test, we investigated the head/neck (CoCrMo/Ti) interface of modular THRs using commercially available heads. Wear and corrosion of taper surfaces was compared following a 10 million loading cycle. Surface parameters and profiles were measured before and after testing. Electrochemical static and dynamic corrosion tests were performed under loaded and non-loaded conditions. After the load test, the surface roughness parameters on the head taper were significantly increased where the head/neck contact area was reduced. Similarly, the surface roughness parameters on the head taper were significantly increased where rough neck tapers were used. Corrosion testing showed breaching of the passive film on the rough but not the smooth neck tapers. Thus, surface area and surface finish are important factors in wear and corrosion at modular interfaces. PMID:23966288

  12. An analytical model to predict interstitial lubrication of cartilage in migrating contact areas

    PubMed Central

    Moore, A.; Burris, D.L.

    2013-01-01

    For nearly a century, articular cartilage has been known for its exceptional tribological properties. For nearly as long, there have been research efforts to elucidate the responsible mechanisms for application toward biomimetic bearing applications. It is now widely accepted that interstitial fluid pressurization is the primary mechanism responsible for the unusual lubrication and load bearing properties of cartilage. Although the biomechanics community has developed elegant mathematical theories describing the coupling of solid and fluid (biphasic) mechanics and its role in interstitial lubrication, quantitative gaps in our understanding of cartilage tribology have inhibited our ability to predict how tribological conditions and material properties impact tissue function. This paper presents an analytical model of the interstitial lubrication of biphasic materials under migrating contact conditions. Although finite element and other numerical models of cartilage mechanics exist, they typically neglect the important role of the collagen network and are limited to a specific set of input conditions, which limits general applicability. The simplified approach taken in this work aims to capture the broader underlying physics as a starting point for further model development. In agreement with existing literature, the model indicates that a large Peclet number, Pe, is necessary for effective interstitial lubrication. It also predicts that the tensile modulus must be large relative to the compressive modulus. This explains why hydrogels and other biphasic materials do not provide significant interstitial pressure under high Pe conditions. The model quantitatively agrees with in-situ measurements of interstitial load support and the results have interesting implications for tissue engineering and osteoarthritis problems. This paper suggests that a low tensile modulus (from chondromalacia or local collagen rupture after impact, for example) may disrupt interstitial

  13. An analytical model to predict interstitial lubrication of cartilage in migrating contact areas.

    PubMed

    Moore, A C; Burris, D L

    2014-01-01

    For nearly a century, articular cartilage has been known for its exceptional tribological properties. For nearly as long, there have been research efforts to elucidate the responsible mechanisms for application toward biomimetic bearing applications. It is now widely accepted that interstitial fluid pressurization is the primary mechanism responsible for the unusual lubrication and load bearing properties of cartilage. Although the biomechanics community has developed elegant mathematical theories describing the coupling of solid and fluid (biphasic) mechanics and its role in interstitial lubrication, quantitative gaps in our understanding of cartilage tribology have inhibited our ability to predict how tribological conditions and material properties impact tissue function. This paper presents an analytical model of the interstitial lubrication of biphasic materials under migrating contact conditions. Although finite element and other numerical models of cartilage mechanics exist, they typically neglect the important role of the collagen network and are limited to a specific set of input conditions, which limits general applicability. The simplified approach taken in this work aims to capture the broader underlying physics as a starting point for further model development. In agreement with existing literature, the model indicates that a large Peclet number, Pe, is necessary for effective interstitial lubrication. It also predicts that the tensile modulus must be large relative to the compressive modulus. This explains why hydrogels and other biphasic materials do not provide significant interstitial pressure under high Pe conditions. The model quantitatively agrees with in-situ measurements of interstitial load support and the results have interesting implications for tissue engineering and osteoarthritis problems. This paper suggests that a low tensile modulus (from chondromalacia or local collagen rupture after impact, for example) may disrupt interstitial

  14. Comparison of occlusal contact areas of class I and class II molar relationships at finishing using three-dimensional digital models

    PubMed Central

    Lee, Hyejoon; Kim, Minji

    2015-01-01

    Objective This study compared occlusal contact areas of ideally planned set-up and accomplished final models against the initial in class I and II molar relationships at finishing. Methods Evaluations were performed for 41 post-orthodontic treatment cases, of which 22 were clinically diagnosed as class I and the remainder were diagnosed as full cusp class II. Class I cases had four first premolars extracted, while class II cases had maxillary first premolars extracted. Occlusal contact areas were measured using a three-dimensional scanner and RapidForm 2004. Independent t-tests were used to validate comparison values between class I and II finishings. Repeated measures analysis of variance was used to compare initial, set up, and final models. Results Molars from cases in the class I finishing for the set-up model showed significantly greater contact areas than those from class II finishing (p < 0.05). The final model class I finishing showed significantly larger contact areas for the second molars (p < 0.05). The first molars of the class I finishing for the final model showed a tendency to have larger contact areas than those of class II finishing, although the difference was not statistically significant (p = 0.078). Conclusions In set-up models, posterior occlusal contact was better in class I than in class II finishing. In final models, class I finishing tended to have larger occlusal contact areas than class II finishing. PMID:26023539

  15. Transmission of Zika Virus Through Sexual Contact with Travelers to Areas of Ongoing Transmission - Continental United States, 2016.

    PubMed

    Hills, Susan L; Russell, Kate; Hennessey, Morgan; Williams, Charnetta; Oster, Alexandra M; Fischer, Marc; Mead, Paul

    2016-03-01

    Zika virus is a flavivirus closely related to dengue, West Nile, and yellow fever viruses. Although spread is primarily by Aedes species mosquitoes, two instances of sexual transmission of Zika virus have been reported, and replicative virus has been isolated from semen of one man with hematospermia. On February 5, 2016, CDC published recommendations for preventing sexual transmission of Zika virus. Updated prevention guidelines were published on February 23. During February 6-22, 2016, CDC received reports of 14 instances of suspected sexual transmission of Zika virus. Among these, two laboratory-confirmed cases and four probable cases of Zika virus disease have been identified among women whose only known risk factor was sexual contact with a symptomatic male partner with recent travel to an area with ongoing Zika virus transmission. Two instances have been excluded based on additional information, and six others are still under investigation. State, territorial, and local public health departments, clinicians, and the public should be aware of current recommendations for preventing sexual transmission of Zika virus, particularly to pregnant women. Men who reside in or have traveled to an area of ongoing Zika virus transmission and have a pregnant partner should abstain from sexual activity or consistently and correctly use condoms during sex with their pregnant partner for the duration of the pregnancy. PMID:26937739

  16. A study of subcooled pool boiling of water: contact area of boiling bubbles with a heating surface during a heating process.

    PubMed

    Suzuki, Koichi; Takahashi, Saika; Ohta, Haruhiko

    2004-11-01

    The contact area of bubbles with a transparent heating surface was optically measured during subcooled pool boiling of water on the ground. In the experiments, boiling bubbles were attached to the heating surface with a bubble holder and nearly reproduced the bubble behavior observed in low gravity. DC power was applied to the ITO heater and increased until the heater surface burned out. In quick heating, that is about 20 second until burnout and equal to the heating time during the low gravity period, the contact area was smaller than that for long time heating at the same heat flux. The experimental results suggest the reason why the critical heat flux in pool boiling is higher than the widely accepted predictions in microgravity. In a drop shaft experiment with constant heating, the contact area increased dramatically at the start of microgravity and became constant. Boiling bubbles coalesced and remained just over the heating surface. PMID:15644360

  17. Effects of tissue conductivity and electrode area on internal electric fields in a numerical human model for ELF contact current exposures

    NASA Astrophysics Data System (ADS)

    Tarao, H.; Kuisti, H.; Korpinen, L.; Hayashi, N.; Isaka, K.

    2012-05-01

    Contact currents flow through the human body when a conducting object with different potential is touched. There are limited reports on numerical dosimetry for contact current exposure compared with electromagnetic field exposures. In this study, using an anatomical human adult male model, we performed numerical calculation of internal electric fields resulting from 60 Hz contact current flowing from the left hand to the left foot as a basis case. Next, we performed a variety of similar calculations with varying tissue conductivity and contact area, and compared the results with the basis case. We found that very low conductivity of skin and a small electrode size enhanced the internal fields in the muscle, subcutaneous fat and skin close to the contact region. The 99th percentile value of the fields in a particular tissue type did not reliably account for these fields near the electrode. In the arm and leg, the internal fields for the muscle anisotropy were identical to those in the isotropy case using a conductivity value longitudinal to the muscle fibre. Furthermore, the internal fields in the tissues abreast of the joints such as the wrist and the elbow, including low conductivity tissues, as well as the electrode contact region, exceeded the ICNIRP basic restriction for the general public with contact current as the reference level value.

  18. Contact dermatitis

    MedlinePlus

    Dermatitis - contact; Allergic dermatitis; Dermatitis - allergic; Irritant contact dermatitis; Skin rash - contact dermatitis ... There are 2 types of contact dermatitis. Irritant dermatitis: This ... can be by contact with acids, alkaline materials such as soaps ...

  19. The Wallpaper Effect: The Contact Hypothesis Fails for Minority Group Members Who Live in Areas with a High Proportion of Majority Group Members

    PubMed Central

    Barlow, Fiona Kate; Hornsey, Matthew J.; Thai, Michael; Sengupta, Nikhil K.; Sibley, Chris G.

    2013-01-01

    We aim to provide one explanation for why the link between contact and prejudice is consistently less strong for minority group members than it is for majority group members. Specifically, we propose a “wallpaper effect” such that contact works to increase minority group members' positivity towards majority groups when they live in areas densely populated with other minority group members. Conversely, we suggest that when minority group members live in neighborhoods patterned with majority group faces (as is so often the case), contact will be less transformative. We test this assumption using a large sample of both New Zealander minority (Māori; N = 925) and majority (European; N = 3805) group members. In line with predictions, Māori who lived in minority dense neighborhoods showed the traditional association between contact and increased warmth towards New Zealander Europeans. This relationship, however, was weak or non-existent when they lived in primarily European neighborhoods. Contact effects in majority group members were unaffected by neighborhood composition. The interaction held when controlling for, and was not explained by: gender, income, experiences of harm, cognitions of race-based rejection, or realistic threat. We provide the first evidence to suggest that when it comes to minority group members' intergroup attitudes, contact with majority group members may be a relatively ineffective predictor unless the “wallpaper” of their lives is minority-dense. PMID:24349227

  20. Precise hypocentral distribution in the source area of the 1964 Niigata earthquake based on an actual crustal model recorded by Ocean Bottom Cabled Seismometers in Japan Sea

    NASA Astrophysics Data System (ADS)

    Machida, Y.; Shimbo, T.; Shinohara, M.; Mochizuki, K.; Yamada, T.; Kanazawa, T.

    2012-12-01

    At the eastern margin of the Japan Sea, large earthquakes have been occurred (e.g., 1964 Niigata earthquake, the 1983 Japan Sea earthquake, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake) along the Niigata-Kobe Tectonic Zone (NKTZ). The NKTZ is recognized as a region of large strain rate along the Japan Sea coast and in the northern Chubu and Kinki distinct. Among these events, the 2004 Chuetsu earthquake and the 2007 Chuetsu-oki earthquake is triggered by reactivation of pre-existing faults within ancient rift systems by stress loading through a ductile creeping of the weak lower crust (Kato et al., 2008). Because the tectonic zone is thought to be spread in offshore region, it is difficult to understand a precise activity of the tectonic zone from only land-base observations. In order to understand precise seismic activities in the NKTZ, especially in offshore region, we installed Ocean Bottom Cabled Seismometers (OBCSs) in the source region of the 1964 Niigata earthquake in 2010 (Shinohara et al., 2010). The OBCS system has a length of 25 km and 4 OBCSs were developed with 5 km interval. The OBCSs have three accelerometers as seismic sensor. We estimated hypocenters using a locations program for finding a maximum likelihood solution using a Bayesian approach (Hirata and Matsu'ura, 1987). We used a simple one dimensional Vp structure, and we assumed a Vp/Vs of 1.73. In general, seismic waves recorded by OBCSs arrive later than those estimated from the average structural model due to unconsolidated sediments just below the sea floor. Therefore the delay of arrival times by the sedimentary layer should be taken into account for the location. In 2011, a seismic survey using airgun and OBCSs was carried out to obtain a seismic velocity model. We obtained station corrections of the P- and S-arrivals for each station using differences of traveltimes estimated by the assumed model and the actual model. This procedure helps us to obtain precise seismic

  1. Effects of mid-foot contact area ratio on lower body kinetics/kinematics in sagittal plane during stair descent in women.

    PubMed

    Lee, Jinkyu; Hong, Yoon No Gregory; Shin, Choongsoo S

    2016-07-01

    The mid-foot contact area relative to the total foot contact area can facilitate foot arch structure evaluation. A stair descent motion consistently provides initial fore-foot contact and utilizes the foot arch more actively for energy absorption. The purpose of this study was to compare ankle and knee joint angle, moment, and work in sagittal plane during stair descending between low and high Mid-Foot-Contact-Area (MFCA) ratio group. The twenty-two female subjects were tested and classified into two groups (high MFCA and low MFCA) using their static MFCA ratios. The ground reaction force (GRF) and kinematics of ankle and knee joints were measured while stair descending. During the period between initial contact and the first peak in vertical GRF (early absorption phase), ankle negative work for the low MFCA ratio group was 33% higher than that for the high MFCA ratio group (p<0.05). However, ankle negative work was not significantly different between the two groups during the period between initial contact and peak dorsiflexion angle (early absorption phase+late absorption phase). The peak ankle dorsiflexion angle was smaller in the low MFCA ratio group (p<0.05). Our results suggest that strategy of energy absorption at the ankle and foot differs depending upon foot arch types classified by MFCA. The low MFCA ratio group seemed to absorb more impact energy using strain in the planar fascia during early absorption phase, whereas the high MFCA ratio group absorbed more impact energy using increased dorsiflexion during late absorption phase. PMID:27477715

  2. The Self Actualized Reader.

    ERIC Educational Resources Information Center

    Marino, Michael; Moylan, Mary Elizabeth

    A study examined the commonalities that "voracious" readers share, and how their experiences can guide parents, teachers, and librarians in assisting children to become self-actualized readers. Subjects, 25 adults ranging in age from 20 to 67 years, completed a questionnaire concerning their reading histories and habits. Respondents varied in…

  3. Contact Dermatitis

    MedlinePlus

    ... care Kids’ zone Video library Find a dermatologist Contact dermatitis Overview Contact dermatitis: Many health care workers ... to touching her face while wearing latex gloves. Contact dermatitis: Overview Almost everyone gets this type of ...

  4. Area contact networks and the spatio-temporal spread of infectious salmon anemia virus (ISAV) in Chile.

    PubMed

    Gustafson, L; Remmenga, M; Sandoval Del Valle, O; Ibarra, R; Antognoli, M; Gallardo, A; Rosenfeld, C; Doddis, J; Enriquez Sais, R; Bell, E; Lara Fica, M

    2016-03-01

    Area management, the coordination of production and biosecurity practices across neighboring farms, is an important disease control strategy in aquaculture. Area management in aquaculture escalated in prominence in response to outbreaks of infectious salmon anemia (ISA) internationally. Successes in disease control have been attributed to the separation achieved through area-level synchronized stocking, fallowing, movement restrictions, and fomite or pest control. Area management, however, is costly; often demanding extra biosecurity, lengthy or inconveniently timed fallows, and localization of equipment, personnel, and services. Yet, this higher-order organizational structure has received limited epidemiologic attention. Chile's National Fisheries and Aquaculture Service instigated area management practices in response to the 2007 emergence of ISA virus (ISAV). Longitudinal data simultaneously collected allowed retrospective evaluation of the impact of component tenets on virus control. Spatiotemporal analyses identified hydrographic linkages, shared ports, and fish transfers from areas with recent occurrence of ISAV as the strongest predictors of virus spread between areas, though specifics varied by ISAV type (here categorized as HPR0 for the non-virulent genotypes, and HPRv otherwise). Hydrographic linkages were most predictive in the period before implementation of enhanced biosecurity and fallowing regulations, suggesting that viral load can impact spread dynamics. HPR0 arose late in the study period, so few HPRv events were available by which to explore the hypothesis of HPR0 as progenitor of outbreaks. However, spatiotemporal patterns in HPRv occurrence were predictive of subsequent patterns in HPR0 detection, suggesting a parallel, or dependent, means of spread. Better data precision, breadth and consistency, common challenges for retrospective studies, could improve model fit; and, for HPR0, specification of diagnostic test accuracy would improve

  5. Effect of Fin-Collar Shape at Contact Area between Tube and Fin on Heat Exchanger Performance

    NASA Astrophysics Data System (ADS)

    Matsuo, Yoshimi; Tsubaki, Koutaro; Miyara, Akio

    In this study, numerical simulation of a cross fin-tube heat exchanger was conducted to investigate the effects of fin-collar shape on the heat transfer performance and pressure drop. During the making process, two adjacent fin-collars and a tube form a triangular space and the end of fin collar protrude to air side. To investigate these effects on the heat exchanger performance, the form ratio was defined to make an indicator of the triangular space size. Furthermore, the simulation of the models with and without protruded end was conducted. The results indicated that the increase of the form ratio results in the decrease in the heat transfer rate. On the other hand, it contributed to a relatively small increase in the heat transfer coefficient on the air side. A high heat transfer coefficient on the air side was obtained by the protruded fin-collar end. However, the pressure drop was not much different between the models with and without the protruded end. The ratio of the thermal contact resistance to the air side thermal resistance was about 1:5 for the form ratio of 20% to 40%.

  6. Transfer of contaminants from surface to hands: experimental assessment of linearity of the exposure process, adherence to the skin, and area exposed during fixed pressure and repeated contact with surfaces contaminated with a powder.

    PubMed

    Brouwer, D H; Kroese, R; Van Hemmen, J J

    1999-04-01

    Estimation of dermal exposure in the workplace resulting from contact with contaminated surfaces is important in risk assessment. Models have been developed to describe the process of exposure due to transfer, but for major input parameters--that is, contact area surface and adherence--defaults are used. This study examines the effect of one single-hand press contact and repeated contacts with a contaminated glass plate on both skin area exposed and loading of the skin for three volunteers. A fluorescent whitening agent was used to study the process of exposure and to determine the increase of the area exposed as well as the adherence of the compound to the skin surface after 1 to 12 consecutive contacts by a video imaging technique. In addition, loading of the skin after 12 contacts was compared to loading of a cotton glove monitor with similar hand pressures. The results show that after one single-hand contact only 4 to 16 percent of the total surface of the palm of the hand was exposed, whereas after 12 contacts this was increased to about 40 percent. The efficiency of transfer was < or = 2 percent of the contamination of the surface. The adherence to the skin was 1.07 micrograms/cm2 after 12 contacts and tended to increase non-linearly with increase in contacts. Because defaults of adherence for use in exposure models are generally a factor 500 to 5,000 higher, and the area exposed is assumed to be the total surface of the hand, overestimation of dermal exposure due to a single hand-surface contact in workplaces may occur. Therefore, additional studies on multi-contact exposure scenarios are indicated to adjust defaults for hand-surface transfer processes. PMID:10457645

  7. Evolution of surface area-to-volume ratio for a water meniscus evaporating between contacting silica spheres.

    PubMed

    Cutts, R E; Burns, S E

    2010-03-01

    An experimental investigation was performed under isothermal conditions to quantify the rate of evaporation of water from a receding pendular meniscus connecting two silica spheres. Optically based measurements were used to determine the relevant meniscus dimensions, and the meniscus was modeled using a toroidal approximation. The rate of change of meniscus surface area and volume was then predicted using mathematical modeling software. The results demonstrated that once the meniscus transitioned from a relatively flat surface to one with an increasing radius of curvature, the rate of change of the ratio of surface area-to-volume was relatively constant over the range of water contents that were observable using the optical investigation techniques implemented in this study. Comparison of the flux of water from the meniscus surface demonstrated that the evaporation of bound water was four orders of magnitude slower than evaporation from a free water surface. PMID:19963221

  8. Self-aligned two-layer metallization with low series resistance for litho-less contacting of large-area photodiodes

    NASA Astrophysics Data System (ADS)

    Mok, K. R. C.; Qi, L.; Vlooswijk, A. H. G.; Nanver, L. K.

    2015-09-01

    In this work, a double-layer Al metallization scheme for large-area photodiodes is presented. This scheme combines a self-alignment of two separate layers of sputtered Al with an anodic Al2O3 as the intermediate insulating layer. One initial patterning step, that could be performed litho-less by for example laser ablation, was needed to define and etch cavities. The cavities provided two Si levels, each of which was contacted by one of the metal layers. Measurement results of test structures showed the effectiveness of this metallization scheme. Despite being partially anodized, the underlying Al layer remained a good conducting layer, with normal low-ohmic behavior. The anodized Al2O3 layer itself acted as a good insulating layer and the two metal layers were not shorted. Furthermore, the characteristics of diodes formed in the textured cavity were as ideal as the planar counterparts. The large two-dimensional coverage of both the anode and cathode by separate metal layers is a promising configuration for low series resistance. Moreover, all steps involved are available on standard integrated circuit (IC) processing equipment, and Al is an abundant cheap metal, making this a very low-cost method of fabricating contacts to large-area devices.

  9. What Actually Happened.

    PubMed

    2016-07-01

    An ethics consult was scheduled for the following day. Prior to the consult, Mr. Hope subsequently decompensated and was transferred to the local hospital. The ethics consultation service continued with the ethics consult to discuss the ethical concerns of the medical staff but in particular to create an open forum for the staff to process their moral distress over the care of this patient and to come to an agreed-on plan on how they would proceed should the resident code. The patient never returned to the long-term care setting. While in the emergency room, the patient took a turn for the worse and appeared to require intubation. The emergency room attending physician contacted the patient's family and discussed the imminent likelihood of the patient's demise and the potential harm caused to the patient by resuscitation and intubation, and the family agreed to switch to comfort measures, allowing the patient to pass peacefully. The family stated to the ER physician that they needed to feel as though they had done everything they could to keep their loved one alive and did not want any responsibility for his death. The staff at the long-term care setting still remember Mr. Hope in their daily work and talk about him often. PMID:27348844

  10. Telocyte's contacts.

    PubMed

    Faussone-Pellegrini, Maria-Simonetta; Gherghiceanu, Mihaela

    2016-07-01

    Telocytes (TC) are an interstitial cell type located in the connective tissue of many organs of humans and laboratory mammals. By means of homocellular contacts, TC build a scaffold whose meshes integrity and continuity are guaranteed by those contacts having a mechanical function; those contacts acting as sites of intercellular communication allow exchanging information and spreading signals. Heterocellular contacts between TC and a great variety of cell types give origin to mixed networks. TC, by means of all these types of contacts, their interaction with the extracellular matrix and their vicinity to nerve endings, are part of an integrated system playing tissue/organ-specific roles. PMID:26826524

  11. Seismic structure of southern margin of the 2011 Tohoku-Oki Earthquake aftershocks area: slab-slab contact zone beneath northeastern Kanto, central Japan

    NASA Astrophysics Data System (ADS)

    Kurashimo, E.; Sato, H.; Abe, S.; Mizohata, S.; Hirata, N.

    2011-12-01

    The 2011 Tohoku-Oki Earthquake (Mw9.0) occurred on the Japan Trench off the eastern shore of northern Honshu, Japan. The southward expansion of the afterslip area has reached the Kanto region, central Japan (Ozawa et al., 2011). The Philippine Sea Plate (PHS) subducts beneath the Kanto region. The bottom of the PHS is in contact with the upper surface of the Pacific Plate (PAC) beneath northeastern Kanto. Detailed structure of the PHS-PAC contact zone is important to constrain the southward rupture process of the Tohoku-Oki Earthquake and provide new insight into the process of future earthquake occurrence beneath the Kanto region. Active and passive seismic experiments were conducted to obtain a structural image beneath northeastern Kanto in 2010 (Sato et al., 2010). The geometry of upper surface of the PHS has been revealed by seismic reflection profiling (Sato et al., 2010). Passive seismic data set is useful to obtain a deep structural image. Two passive seismic array observations were conducted to obtain a detailed structure image of the PHS-PAC contact zone beneath northeastern Kanto. One was carried out along a 50-km-long seismic line trending NE-SW (KT-line) and the other was carried out along a 65-km-long seismic line trending NW-SE (TM-line). Sixty-five 3-component portable seismographs were deployed on KT-line with 500 to 700 m interval and waveforms were continuously recorded during a four-month period from June, 2010. Forty-five 3-component portable seismographs were deployed on TM-line with about 1-2 km spacing and waveforms were continuously recorded during the seven-month period from June, 2010. Arrival times of earthquakes were used in a joint inversion for earthquake locations and velocity structure, using the iterative damped least-squares algorithm, simul2000 (Thurber and Eberhart-Phillips, 1999). The relocated hypocenter distribution shows that the seismicity along the upper surface of the PAC is located at depths of 45-75 km beneath

  12. Theoretical and experimental investigations of nano-Schottky contacts

    NASA Astrophysics Data System (ADS)

    Rezeq, Moh'd.; Eledlebi, Khouloud; Ismail, Mohammed; Dey, Ripon Kumar; Cui, Bo

    2016-07-01

    Formation of metal-semiconductor (M-S) contacts at sub-20 nanometer range is a key requirement for down-scaling of semiconductor devices. However, electrical measurements of M-S contacts at this scale have exhibited dramatic change in the current-voltage (I-V) characteristics compared to that of conventional (or planar) Schottky contacts. This change is actually attributed to the limited metal contact region where the transferred charge from the semiconductor into the metal is confined to a small surface area, which in turn results in an enhanced electric field at the nano-M-S interface. We here present detailed theoretical models to analyze the nano-M-S junctions at 10 nm contact range and then implement this analysis on the experimental data we conducted under these conditions. Both theoretical and experimental results demonstrate a significant effect of the contact size on the electronic structure of the M-S junctions and thus on the I-V characteristics. This effect is rather prominent when the size of the metal contact is substantially smaller than the width of conventional depletion region of the relevant planar M-S contacts.

  13. Binding of sperm protein Izumo1 and its egg receptor Juno drives Cd9 accumulation in the intercellular contact area prior to fusion during mammalian fertilization.

    PubMed

    Chalbi, Myriam; Barraud-Lange, Virginie; Ravaux, Benjamin; Howan, Kevin; Rodriguez, Nicolas; Soule, Pierre; Ndzoudi, Arnaud; Boucheix, Claude; Rubinstein, Eric; Wolf, Jean Philippe; Ziyyat, Ahmed; Perez, Eric; Pincet, Frédéric; Gourier, Christine

    2014-10-01

    Little is known about the molecular mechanisms that induce gamete fusion during mammalian fertilization. After initial contact, adhesion between gametes only leads to fusion in the presence of three membrane proteins that are necessary, but insufficient, for fusion: Izumo1 on sperm, its receptor Juno on egg and Cd9 on egg. What happens during this adhesion phase is a crucial issue. Here, we demonstrate that the intercellular adhesion that Izumo1 creates with Juno is conserved in mouse and human eggs. We show that, along with Izumo1, egg Cd9 concomitantly accumulates in the adhesion area. Without egg Cd9, the recruitment kinetics of Izumo1 are accelerated. Our results suggest that this process is conserved across species, as the adhesion partners, Izumo1 and its receptor, are interchangeable between mouse and human. Our findings suggest that Cd9 is a partner of Juno, and these discoveries allow us to propose a new model of the molecular mechanisms leading to gamete fusion, in which the adhesion-induced membrane organization assembles all key players of the fusion machinery. PMID:25209248

  14. The actual goals of geoethics

    NASA Astrophysics Data System (ADS)

    Nemec, Vaclav

    2014-05-01

    The most actual goals of geoethics have been formulated as results of the International Conference on Geoethics (October 2013) held at the geoethics birth-place Pribram (Czech Republic): In the sphere of education and public enlightenment an appropriate needed minimum know how of Earth sciences should be intensively promoted together with cultivating ethical way of thinking and acting for the sustainable well-being of the society. The actual activities of the Intergovernmental Panel of Climate Changes are not sustainable with the existing knowledge of the Earth sciences (as presented in the results of the 33rd and 34th International Geological Congresses). This knowledge should be incorporated into any further work of the IPCC. In the sphere of legislation in a large international co-operation following steps are needed: - to re-formulate the term of a "false alarm" and its legal consequences, - to demand very consequently the needed evaluation of existing risks, - to solve problems of rights of individuals and minorities in cases of the optimum use of mineral resources and of the optimum protection of the local population against emergency dangers and disasters; common good (well-being) must be considered as the priority when solving ethical dilemmas. The precaution principle should be applied in any decision making process. Earth scientists presenting their expert opinions are not exempted from civil, administrative or even criminal liabilities. Details must be established by national law and jurisprudence. The well known case of the L'Aquila earthquake (2009) should serve as a serious warning because of the proven misuse of geoethics for protecting top Italian seismologists responsible and sentenced for their inadequate superficial behaviour causing lot of human victims. Another recent scandal with the Himalayan fossil fraud will be also documented. A support is needed for any effort to analyze and to disclose the problems of the deformation of the contemporary

  15. A new wetting mechanism based upon triple contact line pinning.

    PubMed

    Liu, Jianlin; Mei, Yue; Xia, Re

    2011-01-01

    The classical Wenzel and Cassie models fail to give a physical explanation of such phenomenon as the macroscopic contact angle actually being equal to the Young's contact angle if there is a spot (surface defect) inside the droplet. Here, we derive the expression of the macroscopic contact angle for this special substrate in use of the principle of least potential energy, and our analytical results are in good agreement with the experimental data. Our findings also suggest that it is the triple contact line (TCL) rather than the contact area that dominates the contact angle. Therefore a new model based upon the TCL pinning is developed to explain the different wetting properties of the Wenzel and Cassie models for hydrophilic and hydrophobic cases. Moreover, the new model predicts the macroscopic contact angle in a broader range accurately, which is consistent with the existing experimental findings. This study revisits the fundamentals of wetting on rough substrates. The new model derived will help to design better superhydrophobic materials and provide the prediction required to engineer novel microfluidic devices. PMID:21117687

  16. Linguistic Theory and Actual Language.

    ERIC Educational Resources Information Center

    Segerdahl, Par

    1995-01-01

    Examines Noam Chomsky's (1957) discussion of "grammaticalness" and the role of linguistics in the "correct" way of speaking and writing. It is argued that the concern of linguistics with the tools of grammar has resulted in confusion, with the tools becoming mixed up with the actual language, thereby becoming the central element in a metaphysical…

  17. An equation to calculate the actual methylene middle parameter as a function of temperature.

    PubMed

    Mohammad, Mohammad Amin

    2015-08-21

    Methylene middle parameter [Formula: see text] , the product of the methylene group's cross-sectional area ( [Formula: see text] ) and the root square of its dispersive free energy ( [Formula: see text] ), is the key parameter to calculate the dispersive surface components of solids (γs(d)) using inverse gas chromatography (IGC) at different temperatures. The only method reported to calculate [Formula: see text] as a function of temperature is the Dorris-Gray method. However, the conventional values of [Formula: see text] calculated by the Dorris-Gray method depend heavily on theoretical aspects. This paper establishes a novel equation calculating the actual [Formula: see text] as a function of temperature using the latest and most accurate surface parameters of seven successive n-alkanes. The obtained actual [Formula: see text] values are slightly higher those of the conventional [Formula: see text] . At 20°C, the actual [Formula: see text] generates γs(d) values less than those generated using the conventional [Formula: see text] by ∼3%, and this reduction in calculated γs(d) values increases linearly to become ∼5% at 100°C. Therefore, using the new actual [Formula: see text] seems to mitigate the discrepancy between the γs(d) values measured by IGC and those measured by the contact angle method. PMID:26187766

  18. Based on the HAAR wavelet processing mine ground and underground contact measurement data

    NASA Astrophysics Data System (ADS)

    Guo, Lei; Wen, Hongyan; Han, Yakun; Kong, Lingshuai; Wang, Qingtao

    2015-12-01

    With the development of measurement technology, using the total station and GPS in the mining area are popular in the mine ground and underground contact measurement. Due to the particularity of the mining area, sometimes the measurement data of low precision can't meet the production requirements. In this paper using HAAR wavelet processing the measured data of a certain coal mine ground and underground contact domestic. To the original data preprocessing, first eliminate noise and then carries on the adjustment. After removed the noise of the late adjustment data quality, is conducive to improve the quality of the final data, to meet actual production needs.

  19. Nanoscale mechanical contacts mapped by ultrashort time-scale electron transport

    PubMed Central

    Tomoda, Motonobu; Dehoux, Thomas; Iwasaki, Yohei; Matsuda, Osamu; Gusev, Vitalyi E.; Wright, Oliver B.

    2014-01-01

    Mechanical contacts are crucial to systems in engineering, electronics and biology. The microscopic nature of the contacting surfaces determines how they mesh on the nanoscale. There is thus much interest in methods that can map the actual area of two surfaces in contact—the real contact area—during the loading or unloading phases. We address this problem using an ultrafast optical technique to generate non-equilibrium electrons that diffuse across a nanoscale mechanical contact between two thin gold films deposited on sapphire. We image this process in the contact and near-contact regions to micron resolution in situ using transient optical reflectivity changes on femtosecond time scales. By use of a model of the ultrashort-time electron dynamics, we account for an up to ~40% drop in the transient optical reflectivity change on contact. We thereby show how the real contact area of a nanoscale contact can be mapped. Applications include the probing of microelectronic mechanical devices. PMID:24763385

  20. Imaging surface contacts: Power law contact distributions and contact stresses in quartz, calcite, glass and acrylic plastic

    USGS Publications Warehouse

    Dieterich, J.H.; Kilgore, B.D.

    1996-01-01

    A procedure has been developed to obtain microscope images of regions of contact between roughened surfaces of transparent materials, while the surfaces are subjected to static loads or undergoing frictional slip. Static loading experiments with quartz, calcite, soda-lime glass and acrylic plastic at normal stresses to 30 MPa yield power law distributions of contact areas from the smallest contacts that can be resolved (3.5 ??m2) up to a limiting size that correlates with the grain size of the abrasive grit used to roughen the surfaces. In each material, increasing normal stress results in a roughly linear increase of the real area of contact. Mechanisms of contact area increase are by growth of existing contacts, coalescence of contacts and appearance of new contacts. Mean contacts stresses are consistent with the indentation strength of each material. Contact size distributions are insensitive to normal stress indicating that the increase of contact area is approximately self-similar. The contact images and contact distributions are modeled using simulations of surfaces with random fractal topographies. The contact process for model fractal surfaces is represented by the simple expedient of removing material at regions where surface irregularities overlap. Synthetic contact images created by this approach reproduce observed characteristics of the contacts and demonstrate that the exponent in the power law distributions depends on the scaling exponent used to generate the surface topography.

  1. ISOLATION OF SALMONELLA ENTERICA AND SHIGA-TOXIGENIC ESCHERICHIA COLI O157 FROM FECES OF ANIMALS IN PUBLIC CONTACT AREAS OF UNITED STATES ZOOLOGICAL PARKS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fecal prevalence of subclinical Salmonella and Shiga-toxigenic Escherichia coli O157 among animals in human-animal contact exhibits at United States Association of Zoos and Aquariums-accredited institutions was estimated to assess public health risk. Prevalence was less than 0.6% for both zoonotic p...

  2. Step edge influence on barrier height and contact area in vertical heterojunctions between epitaxial graphene and n-type 4H-SiC

    SciTech Connect

    Tadjer, M. J. Nyakiti, L. O.; Robinson, Z.; Anderson, T. J.; Myers-Ward, R. L.; Wheeler, V. D.; Eddy, C. R.; Gaskill, D. K.; Koehler, A. D.; Hobart, K. D.; Kub, F. J.

    2014-02-17

    Vertical rectifying contacts of epitaxial graphene grown by Si sublimation on the Si-face of 4H-SiC epilayers were investigated. Forward bias preferential conduction through the step edges was correlated by linear current density normalization. This phenomenon was observed on samples with 2.7–5.8 monolayers of epitaxial graphene as determined by X-ray photoelectron spectroscopy. A modified Richardson plot was implemented to extract the barrier height (0.81 eV at 290 K, 0.99 eV at 30 K) and the electrically dominant SiC step length of a Ti/Al contact overlapping a known region of approximately 0.52 μm wide SiC terraces.

  3. Isolation of Salmonella enterica and Shiga-Toxigenic Escherichia coli O157 from Feces of Animals in Public Contact Areas of United States Zoological Parks▿

    PubMed Central

    Keen, James E.; Durso, Lisa M.; Meehan, Thomas P.

    2007-01-01

    The fecal prevalence of subclinical Salmonella enterica and Shiga-toxigenic Escherichia coli O157 among animals in human-animal contact exhibits at institutions in the United States accredited by the Association of Zoos and Aquariums was estimated to assess public health risk. The prevalence was less than 0.6% for both zoonotic pathogens among 997 animals sampled at 36 exhibits. PMID:17071798

  4. Prioritized Contact Transport Stream

    NASA Technical Reports Server (NTRS)

    Hunt, Walter Lee, Jr. (Inventor)

    2015-01-01

    A detection process, contact recognition process, classification process, and identification process are applied to raw sensor data to produce an identified contact record set containing one or more identified contact records. A prioritization process is applied to the identified contact record set to assign a contact priority to each contact record in the identified contact record set. Data are removed from the contact records in the identified contact record set based on the contact priorities assigned to those contact records. A first contact stream is produced from the resulting contact records. The first contact stream is streamed in a contact transport stream. The contact transport stream may include and stream additional contact streams. The contact transport stream may be varied dynamically over time based on parameters such as available bandwidth, contact priority, presence/absence of contacts, system state, and configuration parameters.

  5. Types of Contact Lenses

    MedlinePlus

    ... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...

  6. How People Actually Use Thermostats

    SciTech Connect

    Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel; Pritoni, Marco

    2010-08-15

    Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.

  7. Thermal Contact Resistance: Experiment Versus Theory

    NASA Astrophysics Data System (ADS)

    Dumont, L.; Moyne, C.; Degiovanni, A.

    1998-11-01

    With a knowledge of the thermal resistance value associated with an asperity, a model for the thermal contact resistance of a given interface is obtained by considering that each asperity of surfaces in contact is a flux tube. Calculation of any of the thermal conductances depends on the contact radius of each asperity. This radius increases with load, as asperities are compressed. Contact area is calculated for a plastic load. Values of thermal contact conductance (or resistance) are compared with experimental results.

  8. Fluid-related modifications of Cr-spinel and olivine from ophiolitic peridotites by contact metamorphism of granitic intrusions in the Ablah area, Saudi Arabia

    NASA Astrophysics Data System (ADS)

    Ahmed, Ahmed Hassan; Surour, Adel Abdullah

    2016-05-01

    The Ablah serpentinized peridotites and overlying layered metagabbros represent an allochthonous piece of a dismembered ophiolite in the southern Hijaz terrane that belongs to the Neoproterozoic Arabian Shield in Saudi Arabia. On both sides, the ophiolite is bounded by wider domains of granitic intrusions and volcano-sedimentary successions, all together follow a N-S trend. The protolith of the Ablah serpentinized peridotites is mainly harzburgite which is partly or totally serpentinized. Carbonate veins of variable sizes invade and hydrate the serpentinized peridotites. Away from the contact with the granitic intrusions, fresh primary (igneous) olivine and Cr-spinel are preserved in the partly serpentinized peridotites. These relict primary minerals are used to infer their tectonic setting of formation as a nascent spreading center rock association of mid-ocean ridge or back-arc basin setting. Based on the re-distribution of elements related to different thermal effects, three patterns of Cr-spinel modification can be defined. The first pattern can be followed in the partly serpentinized peridotites where Cr-spinel displays simple zoning that is characterized by sharp contact between primary Al-rich cores and secondary Fe3+-rich rims. These cores and rims are homogeneous and show progressive decrease in Mg, Al and Cr, but with remarkable increase in Fe3+ and Fe2+ toward the rims. Mineral assemblage in equilibrium with this type of Cr-spinel is primary olivine + antigorite + chlorite ± talc ± chrysotile. The second pattern of Cr-spinel modification is represented by homogeneous weakly zoned Cr-rich spinel with no distinct sharp contacts between Cr-rich cores and magnetite rims. Cr-spinel cores of this type are rich in Cr and Fe2+, and poor in Mg, Al and Fe3+. The mineral assemblage in equilibrium with this Cr-spinel type is Fe-rich olivine + antigorite + enstatite + chlorite + tremolite + anthophyllite ± talc. The third pattern is defined by pervasive

  9. EDITORIAL: Close contact Close contact

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-07-01

    The development of scanning probe techniques, such as scanning tunnelling microscopy [1], has often been touted as the catalyst for the surge in activity and progress in nanoscale science and technology. Images of nanoscale structural detail have served as an invaluable investigative resource and continue to fascinate with the fantastical reality of an intricate nether world existing all around us, but hidden from view of the naked eye by a disparity in scale. As is so often the case, the invention of the scanning tunnelling microscope heralded far more than just a useful new apparatus, it demonstrated the scope for exploiting the subtleties of electronic contact. The shrinking of electronic devices has been a driving force for research into molecular electronics, in which an understanding of the nature of electronic contact at junctions is crucial. In response, the number of experimental techniques in molecular electronics has increased rapidly in recent years. Scanning tunnelling microscopes have been used to study electron transfer through molecular films on a conducting substrate, and the need to monitor the contact force of scanning tunnelling electrodes led to the use of atomic force microscopy probes coated in a conducting layer as studied by Cui and colleagues in Arizona [2]. In this issue a collaboration of researchers at Delft University and Leiden University in the Netherlands report a new device architecture for the independent mechanical and electrostatic tuning of nanoscale charge transport, which will enable thorough studies of molecular transport in the future [3]. Scanning probes can also be used to pattern surfaces, such as through spatially-localized Suzuki and Heck reactions in chemical scanning probe lithography. Mechanistic aspects of spatially confined Suzuki and Heck chemistry are also reported in this issue by researchers in Oxford [4]. All these developments in molecular electronics fabrication and characterization provide alternative

  10. [Contact allergies in musicians].

    PubMed

    Gasenzer, E R; Neugebauer, E A M

    2012-12-01

    During the last years, the problem of allergic diseases has increased. Allergies are errant immune responses to a normally harmless substance. In musicians the allergic contact dermatitis to exotic woods is a special problem. Exotic rosewood contains new flavonoids, which trigger an allergic reaction after permanent contact with the instrument. High quality woodwind instruments such as baroque flute or clarinets are made in ebony or palisander because of its great sound. Today instruments for non-professional players are also made in these exotic materials and non-professionals may have the risk to develop contact dermatitis, too. Brass-player has the risk of an allergic reaction to the different metals contained in the metal sheets of modern flutes and brass instruments. Specially nickel and brass alloys are used to product flute tubes or brass instruments. Special problem arises in children: patients who are allergic to plants or foods have a high risk to develop contact dermatitis. Parents don't know the materials of low-priced instruments for beginners. Often unknown cheap woods from exotic areas are used. Low-priced brass instruments contain high amount of brass and other cheap metals. Physicians should advice musician-patients or parents about the risks of the different materials and look for the reason of eczema on mouth, face, or hands. PMID:23233303

  11. Inter- and intra-rater reliability of patellofemoral kinematic and contact area quantification by fast spin echo MRI and correlation with cartilage health by quantitative T1ρ MRI☆

    PubMed Central

    Lau, Brian C.; Thuillier, Daniel U.; Pedoia, Valentina; Chen, Ellison Y.; Zhang, Zhihong; Feeley, Brian T.; Souza, Richard B.

    2016-01-01

    Background Patellar maltracking is a leading cause of patellofemoral pain syndrome (PFPS). The aim of this study was to determine the inter- and intra-rater reliability of a semi-automated program for magnetic resonance imaging (MRI) based patellofemoral kinematics. Methods Sixteen subjects (10 with PFPS [mean age 32.3; SD 5.2; eight females] and six controls without PFPS 19 [mean age 28.6; SD 2.8; three females]) participated in the study. One set of T2-weighted, fat-saturated fast spin-echo (FSE) MRIs were acquired from each subject in full extension and 30° of knee flexion. MRI including axial T1ρ relaxation time mapping sequences was also performed on each knee. Following image acquisitions, regions of interest for kinematic MRI, and patellar and trochlear cartilage were segmented and quantified with in-house designed spline- based MATLAB semi-automated software. Results Intraclass Correlations Coefficients (ICC) of calculated kinematic parameters were good to excellent, ICC > 0.8 in patellar flexion, rotation, tilt, and translation (anterior -posterior, medial -lateral, and superior -inferior), and contact area translation. Only patellar tilt in the flexed position and motion from extended to flexed state was significantly different between PFPS and control patients (p = 0.002 and p = 0.006, respectively). No significant correlations were identified between patellofemoral kinematics and contact area with T1ρ relaxation times. Conclusions A semi-automated, spline-based kinematic MRI technique for patellofemoral kinematic and contact area quantification is highly reproducible with the potential to help better understand the role of patellofemoral maltracking in PFPS and other knee disorders. PMID:26746045

  12. The actual status of Astronomy in Moldova

    NASA Astrophysics Data System (ADS)

    Gaina, A.

    The astronomical research in the Republic of Moldova after Nicolae Donitch (Donici)(1874-1956(?)) were renewed in 1957, when a satellites observations station was open in Chisinau. Fotometric observations and rotations of first Soviet artificial satellites were investigated under a program SPIN put in action by the Academy of Sciences of former Socialist Countries. The works were conducted by Assoc. prof. Dr. V. Grigorevskij, which conducted also research in variable stars. Later, at the beginning of 60-th, an astronomical Observatory at the Chisinau State University named after Lenin (actually: the State University of Moldova), placed in Lozovo-Ciuciuleni villages was open, which were coordinated by Odessa State University (Prof. V.P. Tsesevich) and the Astrosovet of the USSR. Two main groups worked in this area: first conducted by V. Grigorevskij (till 1971) and second conducted by L.I. Shakun (till 1988), both graduated from Odessa State University. Besides this research areas another astronomical observations were made: Comets observations, astroclimate and atmospheric optics in collaboration with the Institute of the Atmospheric optics of the Siberian branch of the USSR (V. Chernobai, I. Nacu, C. Usov and A.F. Poiata). Comets observations were also made since 1988 by D. I. Gorodetskij which came to Chisinau from Alma-Ata and collaborated with Ukrainean astronomers conducted by K.I. Churyumov. Another part of space research was made at the State University of Tiraspol since the beggining of 70-th by a group of teaching staff of the Tiraspol State Pedagogical University: M.D. Polanuer, V.S. Sholokhov. No a collaboration between Moldovan astronomers and Transdniestrian ones actually exist due to War in Transdniestria in 1992. An important area of research concerned the Radiophysics of the Ionosphere, which was conducted in Beltsy at the Beltsy State Pedagogical Institute by a group of teaching staff of the University since the beginning of 70-th: N. D. Filip, E

  13. Spectral flow dissipation in superconducting point contacts.

    SciTech Connect

    Kopnin, N. B.; Vinokur, V. M.; Materials Science Division; Helsinki Univ. of Technology; L. D. Landau Inst. for Theoretical Physics

    2003-03-15

    We find that multiple Andreev reflections mediating the transport in superconducting point contacts are strongly affected by a small amount of impurities in the area of the contact. We also argue that the model based on Zener transitions within independent conducting channels is not suitable for kinetic processes in multichannel contacts.

  14. Area of Interest 1, CO2 at the Interface. Nature and Dynamics of the Reservoir/Caprock Contact and Implications for Carbon Storage Performance

    SciTech Connect

    Mozley, Peter; Evans, James; Dewers, Thomas

    2014-10-31

    We examined the influence of geologic features present at the reservoir/caprock interface on the transmission of supercritical CO2 into and through caprock. We focused on the case of deformation-band faults in reservoir lithologies that intersect the interface and transition to opening-mode fractures in caprock lithologies. Deformation-band faults are exceeding common in potential CO2 injection units and our fieldwork in Utah indicates that this sort of transition is common. To quantify the impact of these interface features on flow and transport we first described the sedimentology and permeability characteristics of selected sites along the Navajo Sandstone (reservoir lithology) and Carmel Formation (caprock lithology) interface, and along the Slickrock Member (reservoir lithology) and Earthy Member (caprock lithology) of the Entrada Sandstone interface, and used this information to construct conceptual permeability models for numerical analysis. We then examined the impact of these structures on flow using single-phase and multiphase numerical flow models for these study sites. Key findings include: (1) Deformation-band faults strongly compartmentalize the reservoir and largely block cross-fault flow of supercritical CO2. (2) Significant flow of CO2 through the fractures is possible, however, the magnitude is dependent on the small-scale geometry of the contact between the opening-mode fracture and the deformation band fault. (3) Due to the presence of permeable units in the caprock, caprock units are capable of storing significant volumes of CO2, particularly when the fracture network does not extend all the way through the caprock. The large-scale distribution of these deformation-bandfault-to-opening-mode-fractures is related to the curvature of the beds, with greater densities of fractures in high curvature regions. We also examined core and outcrops from the Mount Simon Sandstone and Eau Claire

  15. Actualities and Perspectives in Neurosurgery

    PubMed Central

    Iencean, SM; Brehar, FM

    2008-01-01

    In the field of neurosurgery, like in other surgical specialties, the last decades have brought major achievements. The series of revolutionary discoveries has started during the last century in the fifties, with stereotactic radiosurgery, then continued with the implementation of operative microscope (during the seventies), the endovascular embolisation in the nineties and finally with the major improvement in robotic neurosurgery and molecular neurosurgery at the beginning of this century. The major innovation has been brought not only in the field of therapeutical measures but also in the field of neuro– imaging. Thus, the modern MRI with more than 3 Tesla, can reveal to the neurosurgeon the most intimate structures of the nervous system. Several important areas in neurosurgery like: vascular neurosurgery, functional neurosurgery and brain tumors pathology, benefit from the modern technology and from the latest discoveries from genetic and molecular biology. In conclusion, summarizing the discoveries of the last decade, we emphasize that the related areas like genetics, molecular biology, computer technology become more and more important in the future progress of the neurosurgery. PMID:20108475

  16. Implicit Multibody Penalty-BasedDistributed Contact.

    PubMed

    Xu, Hongyi; Zhao, Yili; Barbic, Jernej

    2014-09-01

    The penalty method is a simple and popular approach to resolving contact in computer graphics and robotics. Penalty-based contact, however, suffers from stability problems due to the highly variable and unpredictable net stiffness, and this is particularly pronounced in simulations with time-varying distributed geometrically complex contact. We employ semi-implicit integration, exact analytical contact gradients, symbolic Gaussian elimination and a SVD solver to simulate stable penalty-based frictional contact with large, time-varying contact areas, involving many rigid objects and articulated rigid objects in complex conforming contact and self-contact. We also derive implicit proportional-derivative control forces for real-time control of articulated structures with loops. We present challenging contact scenarios such as screwing a hexbolt into a hole, bowls stacked in perfectly conforming configurations, and manipulating many objects using actively controlled articulated mechanisms in real time. PMID:26357376

  17. Contact stiffness and damping identification for hardware-in-the-loop contact simulator with measurement delay compensation

    NASA Astrophysics Data System (ADS)

    Qi, Chenkun; Zhao, Xianchao; Gao, Feng; Ren, Anye; Sun, Qiao

    2016-06-01

    The hardware-in-the-loop (HIL) contact simulator is to simulate the contact process of two flying objects in space. The contact stiffness and damping are important parameters used for the process monitoring, compliant contact control and force compensation control. In this study, a contact stiffness and damping identification approach is proposed for the HIL contact simulation with the force measurement delay. The actual relative position of two flying objects can be accurately measured. However, the force measurement delay needs to be compensated because it will lead to incorrect stiffness and damping identification. Here, the phase lead compensation is used to reconstruct the actual contact force from the delayed force measurement. From the force and position data, the contact stiffness and damping are identified in real time using the recursive least squares (RLS) method. The simulations and experiments are used to verify that the proposed stiffness and damping identification approach is effective.

  18. Influence of surface tension on fractal contact model

    NASA Astrophysics Data System (ADS)

    Long, J. M.; Wang, G. F.; Feng, X. Q.; Yu, S. W.

    2014-03-01

    Almost all solid surfaces have roughness on different length scales, from macro, micro to nano. In the conventional fractal contact model, the macroscopic Hertzian contact theory is employed to predict the contact load-area relation for all sizes of contact spots. However, when the contact radius of an asperity shrinks to nanometers, surface tension may greatly alter the contact behavior. In the present paper, we address surface effects on the contact between a rigid sphere and an elastic half space, and we demonstrate that the contact load-area relation is size-dependent, especially for nanosized asperities. Then, the refined contact relation is incorporated into the Majumdar-Bhushan fractal contact model. It is found that the presence of surface tension requires higher load than the conventional fractal contact model to generate the same real contact area.

  19. Adhesive Contact Sweeper

    NASA Technical Reports Server (NTRS)

    Patterson, Jonathan D.

    1993-01-01

    Adhesive contact sweeper removes hair and particles vacuum cleaner leaves behind, without stirring up dust. Also cleans loose rugs. Sweeper holds commercially available spools of inverted adhesive tape. Suitable for use in environments in which air kept free of dust; optics laboratories, computer rooms, and areas inhabited by people allergic to dust. For carpets, best used in tandem with vacuum cleaner; first pass with vacuum cleaner removes coarse particles, and second pass with sweeper extracts fine particles. This practice extends useful life of adhesive spools.

  20. The Apparent Contact Angle and Wetted Area of Active Alloys on Silicon Carbide as a Function of the Temperature and the Surface Roughness: A Multivariate Approach

    NASA Astrophysics Data System (ADS)

    Tillmann, Wolfgang; Pfeiffer, Jan; Wojarski, Lukas

    2015-08-01

    Despite the broad field of applications for active filler alloys for brazing ceramics, as well as intense research work on the wetting and spreading behavior of these alloys on ceramic surfaces within the last decades, the manufactured joints still exhibit significant variations in their properties due to the high sensitivity of the alloys to changing brazing conditions. This increases the need for investigations of the wetting and spreading behavior of filler alloys with regard to the dominating influences combined with their interdependencies, instead of solely focusing on single parameter investigations. In this regard, measurements of the wetting angle and area were conducted at solidified AgCuTi and CuSnTi alloys on SiC substrates. Based on these measurements, a regression model was generated, illustrating the influence of the brazing temperature, the roughness of the faying surfaces, the furnace atmosphere, and their interdependencies on the wetting and spreading behavior of the filler alloys. It was revealed that the behavior of the melts was significantly influenced by the varied brazing parameters, as well as by their interdependencies. This result was also predicted by the developed model and showed a high accuracy.

  1. Irritant Contact Dermatitis

    MedlinePlus

    ... and rashes clinical tools newsletter | contact Share | Irritant Contact Dermatitis Information for adults A A A This ... severe involvement in the patient's armpit. Overview Irritant contact dermatitis is an inflammatory rash caused by direct ...

  2. Contact Lens Risks

    MedlinePlus

    ... Health and Consumer Devices Consumer Products Contact Lenses Contact Lens Risks Share Tweet Linkedin Pin it More ... redness blurred vision swelling pain Serious Hazards of Contact Lenses Symptoms of eye irritation can indicate a ...

  3. Contact Lens Care

    MedlinePlus

    ... For Consumers Consumer Information by Audience For Women Contact Lens Care Share Tweet Linkedin Pin it More ... 1088, www.fda.gov/medwatch Learn More about Contact Lens Care Other Tips on Contact Lenses Decorative ...

  4. Contact Lens Solution Toxicity

    MedlinePlus

    ... rash and rashes clinical tools newsletter | contact Share | Contact Lens Solution Toxicity Information for adults A A A This image shows a reaction to contact lens solution. The prominent blood vessels and redness ...

  5. Access, Prestige and Losses in Contact Languages

    ERIC Educational Resources Information Center

    Parkvall, Mikael

    2013-01-01

    I am generally positive about Muysken's (M) approach, and the potential use of unifying various seemingly related phenomena is obvious. The approach could also serve as a tool in determining to what extent these phenomena actually are sides of the same coin (I am somewhat less convinced of this than most contact linguists).

  6. Dewetting films with inclined contact lines

    NASA Astrophysics Data System (ADS)

    Gao, Peng; Li, Lei; Lu, Xi-Yun

    2015-02-01

    A partially wetting plate withdrawn from a liquid reservoir causes the deposition of a liquid film that is characterized by inclined contact lines. It has been experimentally indicated that the normal component of the contact-line velocity relative to the plate remains constant and is independent of the inclination angles, a fact that has never theoretically been justified. We demonstrate, in the framework of lubrication theory, that the speed-angle independence is only approximate and the normal velocity actually exhibits a weak decrease with the inclination angle of the contact line. This correlation is attributed to the variation of the effective separation of microscopic and macroscopic length scales. In addition, the inclination of the contact line results in a tangential flux of the liquid, which is confined in the vicinity of the contact line. Simple scaling relations are provided for both the normal velocity and the tangential flux.

  7. Comparison of simulated and actual wind shear radar data products

    NASA Technical Reports Server (NTRS)

    Britt, Charles L.; Crittenden, Lucille H.

    1992-01-01

    Prior to the development of the NASA experimental wind shear radar system, extensive computer simulations were conducted to determine the performance of the radar in combined weather and ground clutter environments. The simulation of the radar used analytical microburst models to determine weather returns and synthetic aperture radar (SAR) maps to determine ground clutter returns. These simulations were used to guide the development of hazard detection algorithms and to predict their performance. The structure of the radar simulation is reviewed. Actual flight data results from the Orlando and Denver tests are compared with simulated results. Areas of agreement and disagreement of actual and simulated results are shown.

  8. Moral Reasoning in Hypothetical and Actual Situations.

    ERIC Educational Resources Information Center

    Sumprer, Gerard F.; Butter, Eliot J.

    1978-01-01

    Results of this investigation suggest that moral reasoning of college students, when assessed using the DIT format, is the same whether the dilemmas involve hypothetical or actual situations. Subjects, when presented with hypothetical situations, become deeply immersed in them and respond as if they were actual participants. (Author/BEF)

  9. Factors Related to Self-Actualization.

    ERIC Educational Resources Information Center

    Hogan, H. Wayne; McWilliams, Jettie M.

    1978-01-01

    Provides data to further support the notions that females score higher in self-actualization measures and that self-actualization scores correlate inversely to the degree of undesirability individuals assign to their heights and weights. Finds that, contrary to predictions, greater androgyny was related to lower, not higher, self-actualization…

  10. Non-contact temperature measurement requirements for electronic materials processing

    NASA Technical Reports Server (NTRS)

    Lehoczky, S. L.; Szofran, F. R.

    1988-01-01

    The requirements for non-contact temperature measurement capabilities for electronic materials processing in space are assessed. Non-contact methods are probably incapable of sufficient accuracy for the actual absolute measurement of temperatures in most such applications but would be useful for imaging in some applications.

  11. Electric current induced modification of germanium nanowire NEM switch contact

    NASA Astrophysics Data System (ADS)

    Meija, R.; Kosmaca, J.; Jasulaneca, L.; Petersons, K.; Biswas, S.; Holmes, J. D.; Erts, D.

    2015-05-01

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire’s resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact.

  12. Electric current induced modification of germanium nanowire NEM switch contact.

    PubMed

    Meija, R; Kosmaca, J; Jasulaneca, L; Petersons, K; Biswas, S; Holmes, J D; Erts, D

    2015-05-15

    We present an investigation of contact properties of a germanium (Ge) nanowire based nanoelectromechanical (NEM) switch in its ON state. The contact stiffness in the ON state was evaluated by detecting the nanowire's resonance frequency. It was found that the resonance frequency increases when electric current flows through the nanowire/counter electrode contact area. The reason for modification in the contact area is referred to as electric-current-induced processes in the native oxide layer covering the nanowires. The presented resonance shift method is a simple way to indicate strengthening of the nanowire/counter electrode contact area without disassembling the contact. PMID:25902759

  13. Colored Contact Lens Dangers

    MedlinePlus

    ... Halloween Hazard: The Hidden Dangers of Buying Decorative Contact Lenses Without a Prescription Sep. 26, 2013 It ... she first put in a pair of colored contact lenses, Laura Butler of Parkersburg, W.Va., had " ...

  14. Allergic Contact Dermatitis

    MedlinePlus

    ... causes of allergic contact dermatitis include nickel, chromates, rubber chemicals, and topical antibiotic ointments and creams. Frequent ... construction workers who are in contact with cement. Rubber chemicals are found in gloves, balloons, elastic in ...

  15. Ferromagnetic tunnel contacts to graphene: Contact resistance and spin signal

    SciTech Connect

    Cubukcu, M.; Laczkowski, P.; Vergnaud, C.; Marty, A.; Attané, J.-P.; Notin, L.; Vila, L. Jamet, M.; Martin, M.-B.; Seneor, P.; Anane, A.; Deranlot, C.; Fert, A.; Auffret, S.; Ducruet, C.

    2015-02-28

    We report spin transport in CVD graphene-based lateral spin valves using different magnetic contacts. We compared the spin signal amplitude measured on devices where the cobalt layer is directly in contact with the graphene to the one obtained using tunnel contacts. Although a sizeable spin signal (up to ∼2 Ω) is obtained with direct contacts, the signal is strongly enhanced (∼400 Ω) by inserting a tunnel barrier. In addition, we studied the resistance-area product (R.A) of a variety of contacts on CVD graphene. In particular, we compared the R.A products of alumina and magnesium oxide tunnel barriers grown by sputtering deposition of aluminum or magnesium and subsequent natural oxidation under pure oxygen atmosphere or by plasma. When using an alumina tunnel barrier on CVD graphene, the R.A product is high and exhibits a large dispersion. This dispersion can be highly reduced by using a magnesium oxide tunnel barrier, as for the R.A value. This study gives insight in the material quest for reproducible and efficient spin injection in CVD graphene.

  16. Northrop Triga facility decommissioning plan versus actual results

    SciTech Connect

    Gardner, F.W.

    1986-01-01

    This paper compares the Triga facility decontamination and decommissioning plan to the actual results and discusses key areas where operational activities were impacted upon by the final US Nuclear Regulatory Commission (NRC)-approved decontamination and decommissioning plan. Total exposures for fuel transfer were a factor of 4 less than planned. The design of the Triga reactor components allowed the majority of the components to be unconditionally released.

  17. Glasses and Contact Lenses

    MedlinePlus

    ... Here's Help White House Lunch Recipes Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A Text Size What's ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  18. Salt deposition at particle contact points

    NASA Astrophysics Data System (ADS)

    Nie, Xiaodong; Evitts, Richard W.; Besant, Robert W.; Kennell, Glyn F.

    2015-09-01

    Caking may occur when granular potash fertilizer with a moisture content greater than 0.25 % (w/w) undergoes drying. Since cake strength is proportional to the mass of crystal deposited per unit volume near contact points (and other factors) the modelling of mass deposition near contact points is important. The Young-Laplace equation for the air-salt-solution interface is used to determine the geometry of a 2-D planar saline film between two cubic potash particles. A 2-D theoretical model is developed and applied for ion diffusion and deposition near the contact point during drying. The numerical predictions of ion diffusion in an initially saturated salt illustrate the transient spatial distribution of new KCl deposits along the solid surfaces near the contact line. These results indicate the average salt deposition commences at the air-liquid-solid intersection, where the liquid film is thinnest, and moves toward the particle contact point with increasing area averaged KCl deposits, causing the formation of crystal deposits and bridges near contact points. It is concluded that the average salt deposit height increases inversely with distance from the contact point and decreases with initial contact angle of the contact region, but the deposition is nearly independent of the evaporation or drying rate near each contact region. Caking strength depends on, among other parameters, the amount of salt deposition near contact points.

  19. Contact lens in keratoconus

    PubMed Central

    Rathi, Varsha M; Mandathara, Preeji S; Dumpati, Srikanth

    2013-01-01

    Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL. PMID:23925325

  20. Disproportionate minority contact.

    PubMed

    Piquero, Alex R

    2008-01-01

    For many years, notes Alex Piquero, youth of color have been overrepresented at every stage of the U.S. juvenile justice system. As with racial disparities in a wide variety of social indicators, the causes of these disparities are not immediately apparent. Some analysts attribute the disparities to "differential involvement"--that is, to differences in offending by minorities and whites. Others attribute them to "differential selection"--that is, to the fact that the justice system treats minority and white offenders in different ways. Still others believe the explanation lies in a combination of the two. Differential involvement may be important earlier in the judicial process, especially in youths' contacts with police, and may influence differential selection later as individuals make their way through the juvenile justice system. Adjudicating between these options, says Piquero, is difficult and may even be impossible. Asking how much minority overrepresentation is due to differences in offending and how much to differences in processing no longer seems a helpful way to frame the discussion. Piquero urges future research to move beyond the debate over "which one matters more" and seek to understand how each of the two hypotheses can explain both the fact of minority overrepresentation in the juvenile justice system and how best to address it. Piquero cites many sizable gaps in the research and policy-relevant literature. Work is needed especially, he says, in analyzing the first stage of the justice system that juveniles confront: police contacts. The police are a critical part of the juvenile justice decision-making system and are afforded far more discretion than any other formal agent of social control, but researchers have paid surprisingly little attention to contacts between police and citizens, especially juveniles. Piquero notes that some states and localities are undertaking initiatives to reduce racial and ethnic disparities. He urges researchers and

  1. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  2. Ink-Jet Printer Forms Solar-Cell Contacts

    NASA Technical Reports Server (NTRS)

    Alexander, Paul, Jr.; Vest, R. W.; Binford, Don A.; Tweedell, Eric P.

    1988-01-01

    Contacts formed in controllable patterns with metal-based inks. System forms upper metal contact patterns on silicon photovoltaic cells. Uses metallo-organic ink, decomposes when heated, leaving behind metallic, electrically conductive residue in printed area.

  3. Remedial Action Contacts Directory - 1997

    SciTech Connect

    1997-05-01

    This document, which was prepared for the US Department of Energy (DOE) Office of Environmental Restoration (ER), is a directory of 2628 individuals interested or involved in environmental restoration and/or remedial actions at radioactively contaminated sites. This directory contains a list of mailing addresses and phone numbers of DOE operations, area, site, project, and contractor offices; an index of DOE operations, area, site, project, and contractor office sorted by state; a list of individuals, presented by last name, facsimile number, and e-mail address; an index of affiliations presented alphabetically, with individual contacts appearing below each affiliation name; and an index of foreign contacta sorted by country and affiliation. This document was generated from the Remedial Action Contacts Database, which is maintained by the Remedial Action Program Information Center (RAPIC).

  4. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  5. 50 CFR 253.16 - Actual cost.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 11 2013-10-01 2013-10-01 false Actual cost. 253.16 Section 253.16 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE AID TO FISHERIES FISHERIES ASSISTANCE PROGRAMS Fisheries Finance Program §...

  6. Humanistic Education and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1984-01-01

    Stresses the need for theoretical justification for the development of humanistic education programs in today's schools. Explores Abraham Maslow's hierarchy of needs and theory of self-actualization. Argues that Maslow's theory may be the best available for educators concerned with educating the whole child. (JHZ)

  7. Children's Rights and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1982-01-01

    Educators need to seriously reflect upon the concept of children's rights. Though the idea of children's rights has been debated numerous times, the idea remains vague and shapeless; however, Maslow's theory of self-actualization can provide the children's rights idea with a needed theoretical framework. (Author)

  8. Culture Studies and Self-Actualization Theory.

    ERIC Educational Resources Information Center

    Farmer, Rod

    1983-01-01

    True citizenship education is impossible unless students develop the habit of intelligently evaluating cultures. Abraham Maslow's theory of self-actualization, a theory of innate human needs and of human motivation, is a nonethnocentric tool which can be used by teachers and students to help them understand other cultures. (SR)

  9. Group Counseling for Self-Actualization.

    ERIC Educational Resources Information Center

    Streich, William H.; Keeler, Douglas J.

    Self-concept, creativity, growth orientation, an integrated value system, and receptiveness to new experiences are considered to be crucial variables to the self-actualization process. A regular, year-long group counseling program was conducted with 85 randomly selected gifted secondary students in the Farmington, Connecticut Public Schools. A…

  10. Racial Discrimination in Occupations: Perceived and Actual.

    ERIC Educational Resources Information Center

    Turner, Castellano B.; Turner, Barbara F.

    The relationship between the actual representation of Blacks in certain occupations and individual perceptions of the occupational opportunity structure were examined. A scale which rated the degree of perceived discrimination against Blacks in 21 occupations was administered to 75 black male, 70 black female, 1,429 white male and 1,457 white…

  11. Developing Human Resources through Actualizing Human Potential

    ERIC Educational Resources Information Center

    Clarken, Rodney H.

    2012-01-01

    The key to human resource development is in actualizing individual and collective thinking, feeling and choosing potentials related to our minds, hearts and wills respectively. These capacities and faculties must be balanced and regulated according to the standards of truth, love and justice for individual, community and institutional development,…

  12. Whiteheadian Actual Entitities and String Theory

    NASA Astrophysics Data System (ADS)

    Bracken, Joseph A.

    2012-06-01

    In the philosophy of Alfred North Whitehead, the ultimate units of reality are actual entities, momentary self-constituting subjects of experience which are too small to be sensibly perceived. Their combination into "societies" with a "common element of form" produces the organisms and inanimate things of ordinary sense experience. According to the proponents of string theory, tiny vibrating strings are the ultimate constituents of physical reality which in harmonious combination yield perceptible entities at the macroscopic level of physical reality. Given that the number of Whiteheadian actual entities and of individual strings within string theory are beyond reckoning at any given moment, could they be two ways to describe the same non-verifiable foundational reality? For example, if one could establish that the "superject" or objective pattern of self- constitution of an actual entity vibrates at a specific frequency, its affinity with the individual strings of string theory would be striking. Likewise, if one were to claim that the size and complexity of Whiteheadian 'societies" require different space-time parameters for the dynamic interrelationship of constituent actual entities, would that at least partially account for the assumption of 10 or even 26 instead of just 3 dimensions within string theory? The overall conclusion of this article is that, if a suitably revised understanding of Whiteheadian metaphysics were seen as compatible with the philosophical implications of string theory, their combination into a single world view would strengthen the plausibility of both schemes taken separately. Key words: actual entities, subject/superjects, vibrating strings, structured fields of activity, multi-dimensional physical reality.

  13. Colors and contact dermatitis.

    PubMed

    Bonamonte, Domenico; Foti, Caterina; Romita, Paolo; Vestita, Michelangelo; Angelini, Gianni

    2014-01-01

    The diagnosis of skin diseases relies on several clinical signs, among which color is of paramount importance. In this review, we consider certain clinical presentations of both eczematous and noneczematous contact dermatitis in which color plays a peculiar role orientating toward the right diagnosis. The conditions that will be discussed include specific clinical-morphologic subtypes of eczematous contact dermatitis, primary melanocytic, and nonmelanocytic contact hyperchromia, black dermographism, contact chemical leukoderma, and others. Based on the physical, chemical, and biologic factors underlying a healthy skin color, the various skin shades drawing a disease picture are thoroughly debated, stressing their etiopathogenic origins and histopathologic aspects. PMID:25000236

  14. Constructions of contact manifolds

    NASA Astrophysics Data System (ADS)

    Geiges, Hansjörg

    1997-05-01

    1. IntroductionIt has been known for some time that contact structures show a high degree of topological flexibility in the sense that many topological operations can be performed on contact manifolds while preserving the contact property. For instance, Martinet [14] used a surgery description of 3-manifolds to show that every closed, oriented 3-manifold admits a contact structure, and alternative proofs of this result were given later by Thurston and Winkelnkemper [18], who based their proof on an open book decomposition, and Gonzalo [8], who used branched covers. These, however, are all strictly 3-dimensional constructions.

  15. Optical contact micrometer

    DOEpatents

    Jacobson, Steven D.

    2014-08-19

    Certain examples provide optical contact micrometers and methods of use. An example optical contact micrometer includes a pair of opposable lenses to receive an object and immobilize the object in a position. The example optical contact micrometer includes a pair of opposable mirrors positioned with respect to the pair of lenses to facilitate viewing of the object through the lenses. The example optical contact micrometer includes a microscope to facilitate viewing of the object through the lenses via the mirrors; and an interferometer to obtain one or more measurements of the object.

  16. A 3D Contact Smoothing Method

    SciTech Connect

    Puso, M A; Laursen, T A

    2002-05-02

    Smoothing of contact surfaces can be used to eliminate the chatter typically seen with node on facet contact and give a better representation of the actual contact surface. The latter affect is well demonstrated for problems with interference fits. In this work we present two methods for the smoothing of contact surfaces for 3D finite element contact. In the first method, we employ Gregory patches to smooth the faceted surface in a node on facet implementation. In the second method, we employ a Bezier interpolation of the faceted surface in a mortar method implementation of contact. As is well known, node on facet approaches can exhibit locking due to the failure of the Babuska-Brezzi condition and in some instances fail the patch test. The mortar method implementation is stable and provides optimal convergence in the energy of error. In the this work we demonstrate the superiority of the smoothed versus the non-smoothed node on facet implementations. We also show where the node on facet method fails and some results from the smoothed mortar method implementation.

  17. Enhanced process control of submicron contact definition

    NASA Astrophysics Data System (ADS)

    Ostrout, Wayne H.; Hunkler, Sean; Ward, Steven D.

    1991-03-01

    The aggressive drive to reduce device geometries to submicron levels while utilizing ULSI design capabilities has posed many challenges to traditional semiconductor process technology. Among the most critical is the ability to maintain satisfactory contact between two levels of metal through contact holes significantly smaller than the actual design rule itself. Traditional technologies for greater than one micron design rules are not capable of maintaining the consistent output necessary to achieve and maintain Six Sigma process control. Isotropic plasma etching of doped and undoped oxides has been studied as an alternative to the " wet" isotropic etch in the traditional " wet-dry" contact hole etch process scheme. The isotropic etch was characterized using Taguchi and Response Surface Methodology (RSM) multilevel statistical experimental designs. Optimized conditions resulted in process capability of greater than 2. 0 Cpk control measured in reference to critical dimension performance and electrical data analysis.

  18. Photometric Study of Near Contact Binaries

    NASA Astrophysics Data System (ADS)

    Zhu, L.; Qian, S.

    2009-08-01

    Near Contact Binary (NCB) is a kind of close binary in which both components fill or nearly fill their critical Roche Lobes. They are not in contact like W UMa systems, and show EB-type light variations. These characters make the NCB an interesting object. They are important observational targets which may be lying in key evolutionary states. According to the geometric definition of this subclass, NCBs actually comprise semi-detached with primary filling (SD1) or secondary filling (SD2), marginal-contact (C), and marginal-detached (D) systems. We have observed a group of NCBs (e.g. BL and, GW Tau, AS Ser, UU Lyn, RU UMi, GSC3658-0076 etc. ) and constructed an evolutionary sequence of case A mass transfer in observation. Finally, the available orbital period variations and absolute parameters of NCBs are collected and the preliminary statistical results are presented.

  19. The Actual Apollo 13 Prime Crew

    NASA Technical Reports Server (NTRS)

    1970-01-01

    The actual Apollo 13 lunar landing mission prime crew from left to right are: Commander, James A. Lovell Jr., Command Module pilot, John L. Swigert Jr.and Lunar Module pilot, Fred W. Haise Jr. The original Command Module pilot for this mission was Thomas 'Ken' Mattingly Jr. but due to exposure to German measles he was replaced by his backup, Command Module pilot, John L. 'Jack' Swigert Jr.

  20. Effects of insoles contact on static balance

    PubMed Central

    Shin, Ju Yong; Ryu, Young Uk; Yi, Chae Woo

    2016-01-01

    [Purpose] This study examined the effect of the degree of the contact area between the insoles and soles on static balance. [Subjects and Methods] Thirteen healthy male and female adults voluntarily participated. All of the subjects wore three different types of insoles (no orthotic insole, partial contact, full contact) in the present experiment. The subjects were instructed to place both feet parallel to each other and maintain static balance for 30 seconds. Center of pressure parameters (range, total distance, and mean velocity) were analyzed. [Results] The results show that the anteroposterior range and mediolateral (ML) total distance and velocity decreased when orthotic insoles with partial contact or full contact were used in comparison to when a flat insole (no orthotic insole) was used. Also, the ML range and total distance were lower with full contact than in the other two conditions. These results indicate that static balance improves as the degree of contact between the soles and insoles increases. [Conclusion] The results of this study suggests that using insoles with increased sole contact area would improve static balance ability. PMID:27190460

  1. Language Contact: An Introduction.

    ERIC Educational Resources Information Center

    Thomason, Sarah G.

    This book surveys situations in which language contact arises and focuses on what happens to the languages themselves: sometimes nothing, sometimes the incorporation of new words, sometimes the spread of new sounds and sentence structures across many languages and wide swathes of territory. It outlines the origins and results of contact-induced…

  2. Miniature intermittent contact switch

    NASA Technical Reports Server (NTRS)

    Sword, A.

    1972-01-01

    Design of electric switch for providing intermittent contact is presented. Switch consists of flexible conductor surrounding, but separated from, fixed conductor. Flexing of outside conductor to contact fixed conductor completes circuit. Advantage is small size of switch compared to standard switches.

  3. Noneczematous Contact Dermatitis

    PubMed Central

    Foti, Caterina; Vestita, Michelangelo; Angelini, Gianni

    2013-01-01

    Irritant or allergic contact dermatitis usually presents as an eczematous process, clinically characterized by erythematoedematovesicous lesions with intense itching in the acute phase. Such manifestations become erythematous-scaly as the condition progresses to the subacute phase and papular-hyperkeratotic in the chronic phase. Not infrequently, however, contact dermatitis presents with noneczematous features. The reasons underlying this clinical polymorphism lie in the different noxae and contact modalities, as well as in the individual susceptibility and the various targeted cutaneous structures. The most represented forms of non-eczematous contact dermatitis include the erythema multiforme-like, the purpuric, the lichenoid, and the pigmented kinds. These clinical entities must obviously be discerned from the corresponding “pure” dermatitis, which are not associated with contact with exogenous agents. PMID:24109520

  4. Electrical Contacts to Nanomaterials.

    PubMed

    Bandaru, P R; Faraby, H; DiBattista, M

    2015-12-01

    The efficient passage of electrical current from an external contact to a nanomaterial is necessary for harnessing characteristics unique to the nanoscale, such as those relevant to energy quantization. However, an intrinsic resistance pertinent to dimensionality crossover and the presence of impurities precludes optimal electrical contact formation. In this review, we first discuss the relevant principles and contact resistance measurement methodologies, with modifications necessary for the nanoscale. Aspects related to the deposition of the contact material are deemed to be crucial. Consequently, the use of focused ion beam (FIB) based deposition, which relies on the ion-induced decomposition of a metallorganic precursor, and which has been frequently utilized for nanoscale contacts is considered in detail. PMID:26682353

  5. Electrical contacts to individual SWCNTs: A review

    PubMed Central

    Hierold, Christofer; Haluska, Miroslav

    2014-01-01

    Summary Owing to their superior electrical characteristics, nanometer dimensions and definable lengths, single-walled carbon nanotubes (SWCNTs) are considered as one of the most promising materials for various types of nanodevices. Additionally, they can be used as either passive or active elements. To be integrated into circuitry or devices, they are typically connected with metal leads to provide electrical contacts. The properties and quality of these electrical contacts are important for the function and performance of SWCNT-based devices. Since carbon nanotubes are quasi-one-dimensional structures, contacts to them are different from those for bulk semiconductors. Additionally, some techniques used in Si-based technology are not compatible with SWCNT-based device fabrication, such as the contact area cleaning technique. In this review, an overview of the investigations of metal–SWCNT contacts is presented, including the principle of charge carrier injection through the metal–SWCNT contacts and experimental achievements. The methods for characterizing the electrical contacts are discussed as well. The parameters which influence the contact properties are summarized, mainly focusing on the contact geometry, metal type and the cleanliness of the SWCNT surface affected by the fabrication processes. Moreover, the challenges for widespread application of CNFETs are additionally discussed. PMID:25551048

  6. Perceived accessibility versus actual physical accessibility of healthcare facilities.

    PubMed

    Sanchez, J; Byfield, G; Brown, T T; LaFavor, K; Murphy, D; Laud, P

    2000-01-01

    This study addressed how healthcare clinics perceive themselves in regard to accessibility for persons with spinal cord injuries (SCI). All 40 of the clinics surveyed reported that they were wheelchair accessible; however, there was significant variability in the number of sites that actually met the guidelines of the Americans with Disability Act. In general, a person using a wheelchair could enter the building, the examination room, and the bathroom. The majority of sites did not have an examination table that could be lowered to wheelchair level. Most reported limited experience in working with persons with (SCI), yet they claimed to be able to assist with difficult transfers. Only one site knew about autonomic dysreflexia. Problems of accessibility appeared to be seriously compounded by the clinics' perception of how they met physical accessibility guidelines without consideration of the actual needs of persons with SCI. This study addressed the perception of accessibility as reported by clinic managers versus actual accessibility in healthcare clinics in a Midwestern metropolitan area for persons using wheelchairs. PMID:10754921

  7. Correlation of ideal and actual shear strengths of metals with their friction properties

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1981-01-01

    The relation between the ideal and actual shear strengths and friction properties of clean metals in contact with clean diamond, boron nitride, silicon carbide, manganese-zinc ferrite, and the metals themselves in vacuum is discussed. An estimate of the ideal shear strength for metals is obtained from the shear modulus, the repeat distance of atoms in the direction of shear of the metal, and the interplanar spacing of the shearing planes. The coefficient of friction for metals is shown to be correlated with both the ideal and actual shear strength of metals. The higher the strength of the metal, the lower the coefficient of friction occurs.

  8. Mixed formulation for frictionless contact problems

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Kim, Kyun O.

    1989-01-01

    Simple mixed finite element models and a computational precedure are presented for the solution of frictionless contact problems. The analytical formulation is based on a form of Reissner's large rotation theory of the structure with the effects of transverse shear deformation included. The contact conditions are incorporated into the formulation by using a perturbed Lagrangian approach with the fundamental unknowns consisting of the internal forces (stress resultants), the generalized displacements, and the Lagrange multipliers associated with the contact conditions. The element characteristic array are obtained by using a modified form of the two-field Hellinger-Reissner mixed variational principle. The internal forces and the Lagrange multipliers are allowed to be discontinuous at interelement boundaries. The Newton-Raphson iterative scheme is used for the solution of the nonlinear algebraic equations, and the determination of the contact area and the contact pressures.

  9. Telescopic vision contact lens

    NASA Astrophysics Data System (ADS)

    Tremblay, Eric J.; Beer, R. Dirk; Arianpour, Ashkan; Ford, Joseph E.

    2011-03-01

    We present the concept, optical design, and first proof of principle experimental results for a telescopic contact lens intended to become a visual aid for age-related macular degeneration (AMD), providing magnification to the user without surgery or external head-mounted optics. Our contact lens optical system can provide a combination of telescopic and non-magnified vision through two independent optical paths through the contact lens. The magnified optical path incorporates a telescopic arrangement of positive and negative annular concentric reflectors to achieve 2.8x - 3x magnification on the eye, while light passing through a central clear aperture provides unmagnified vision.

  10. Optical contacting of quartz

    NASA Technical Reports Server (NTRS)

    Payne, L. L.

    1982-01-01

    The strength of the bond between optically contacted quartz surfaces was investigated. The Gravity Probe-B (GP-B) experiment to test the theories of general relativity requires extremely precise measurements. The quartz components of the instruments to make these measurements must be held together in a very stable unit. Optical contacting is suggested as a possible method of joining these components. The fundamental forces involved in optical contacting are reviewed and relates calculations of these forces to the results obtained in experiments.

  11. Air resistance measurements on actual airplane parts

    NASA Technical Reports Server (NTRS)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  12. Contact dermatitis: facts and controversies.

    PubMed

    Wolf, Ronni; Orion, Edith; Ruocco, Eleonora; Baroni, Adone; Ruocco, Vincenzo

    2013-01-01

    The history of contact dermatitis (CD) is inseparable from the history of the patch test, and the patch test is inseparable from the pioneer in the field, Josef Jadassohn (1860-1936). Despite the fact that we have been diagnosing, treating, and investigating the condition for more than 100 years, there are still many unsolved questions and controversies, which show no signs of coming to an end in the foreseeable future. This contribution reviews and highlights some of the disagreements and discrepancies associated with CD. For example: • What is the real sensitizer in balsam of Peru, one of the most common allergens, and what, if any, is the value of a low-balsam diet? • Is benzalkonium chloride, which has well-known and undisputed irritant properties, a contact allergen as well? • Is cocamidopropyl betaine (CABP) a common contact allergen and what is the actual sensitizer in CABP allergy the molecule itself, or impurities, or intermediaries in its synthesis? • How can the significant differences in the prevalence of sensitization of formaldehyde (FA, a common cause of contact allergy) between the United States (8%-9%) and Europe (2%-3%) be explained? • What is the relationship between formaldehyde releasers (FRs) allergy and an FA allergy? Should we recommend that FA-allergic patients also avoid FRs, and, if so, to what extent? • What is the true frequency of lanolin allergy? This issue remains enigmatic despite the expenditure of thousands of dollars and the innumerable hours spent investigating this subject. • What is the basis behind the so-called "lanolin paradox"? This label was coined in 1996 and is still a matter of controversy. • Is there such a thing as systemic CD from nickel, and, if so, to what extent? Is there a cross-reactivity or concomitant sensitization between nickel and cobalt?These are some of the controversial problems discussed. We have selected the ones that we consider to be of special interest and importance to the

  13. Occupational Contact Dermatitis

    PubMed Central

    2008-01-01

    Occupational contact dermatitis accounts for 90% of all cases of work-related cutaneous disorders. It can be divided into irritant contact dermatitis, which occurs in 80% of cases, and allergic contact dermatitis. In most cases, both types will present as eczematous lesions on exposed parts of the body, notably the hands. Accurate diagnosis relies on meticulous history taking, thorough physical examination, careful reading of Material Safety Data Sheets to distinguish between irritants and allergens, and comprehensive patch testing to confirm or rule out allergic sensitization. This article reviews the pathogenesis and clinical manifestations of occupational contact dermatitis and provides diagnostic guidelines and a rational approach to management of these often frustrating cases. PMID:20525126

  14. Contacting American Overseas Schools.

    ERIC Educational Resources Information Center

    Engelhardt, David

    1993-01-01

    Provides contacts for architects or educational consultants who wish to work overseas. Cites a directory, newsletters, newspapers, and associations focused on educators involved with independent overseas schools that are organized around the United States curriculum. (MLF)

  15. ELECTRIC CONTACT MEANS

    DOEpatents

    Grear, J.W. Jr.

    1959-03-10

    A switch adapted to maintain electrical connections under conditions of vibration or acceleration is described. According to the invention, thc switch includes a rotatable arm carrying a conductive bar arranged to close against two contacts spaced in the same plane. The firm and continuous engagement of the conductive bar with the contacts is acheived by utilizeing a spring located betwenn the vbar and athe a rem frzme and slidable mounting the bar in channel between two arms suspendef from the arm frame.

  16. The impact of contact

    NASA Astrophysics Data System (ADS)

    Finney, B.

    1986-10-01

    Scenarios of the impact on human society of radio contact with an extraterrestrial civilization are presented. Some believe that contact with advanced extraterrestrials would quickly devastate the human spirit, while others believe that these super-intelligent beings would show the inhabitants of the earth how to live in peace. It is proposed that the possible existence of extraterrestrial civilizations and the development of means of studying and communicating with them need to be considered.

  17. Contact dermatitis complicating pinnaplasty.

    PubMed

    Singh-Ranger, G; Britto, J A; Sommerlad, B C

    2001-04-01

    Proflavine allergy is uncommon, occurring in approximately 6% of patients attending contact dermatitis clinics. Proflavine wool is used by many surgeons in the UK as a dressing that can be moulded to conform to the contours of a corrected prominent ear. It may have bacteriostatic properties. We present a case where contact dermatitis in response to proflavine developed after pinnaplasty. This caused diagnostic confusion, a lengthened hospital stay and an unsightly hypertrophic scar. PMID:11254419

  18. Multibody dynamic simulation of knee contact mechanics

    PubMed Central

    Bei, Yanhong; Fregly, Benjamin J.

    2006-01-01

    Multibody dynamic musculoskeletal models capable of predicting muscle forces and joint contact pressures simultaneously would be valuable for studying clinical issues related to knee joint degeneration and restoration. Current three-dimensional multi-body knee models are either quasi-static with deformable contact or dynamic with rigid contact. This study proposes a computationally efficient methodology for combining multibody dynamic simulation methods with a deformable contact knee model. The methodology requires preparation of the articular surface geometry, development of efficient methods to calculate distances between contact surfaces, implementation of an efficient contact solver that accounts for the unique characteristics of human joints, and specification of an application programming interface for integration with any multibody dynamic simulation environment. The current implementation accommodates natural or artificial tibiofemoral joint models, small or large strain contact models, and linear or nonlinear material models. Applications are presented for static analysis (via dynamic simulation) of a natural knee model created from MRI and CT data and dynamic simulation of an artificial knee model produced from manufacturer’s CAD data. Small and large strain natural knee static analyses required 1 min of CPU time and predicted similar contact conditions except for peak pressure, which was higher for the large strain model. Linear and nonlinear artificial knee dynamic simulations required 10 min of CPU time and predicted similar contact force and torque but different contact pressures, which were lower for the nonlinear model due to increased contact area. This methodology provides an important step toward the realization of dynamic musculoskeletal models that can predict in vivo knee joint motion and loading simultaneously. PMID:15564115

  19. Contact resistance of 500 mesh regenerator screens

    NASA Astrophysics Data System (ADS)

    Lee, A. C.; Ravikumar, K. V.; Frederking, T. H. K.

    The electrical contact resistance of stainless steel screen stacks at room temperature and at liquid nitrogen temperature has been measured as a function of externally applied mechanical load (weight). The data show a nearly linear voltage versus current function at small loads (up to 100 mA). The force has been varied up to a specific load of 1 N cm -2. From the data the (apparent) thermal conductance is deduced via the Lorenz number and via the (average) elastically deformed contact domain area of the Hertz theory. The conductances obtained appear to be consistent with literature data for thermal contact conductances of similar systems.

  20. On contact problems of elasticity theory

    NASA Technical Reports Server (NTRS)

    Kalandiya, A. I.

    1986-01-01

    Certain contact problems are reviewed in the two-dimensional theory of elasticity when round bodies touch without friction along most of the boundary and, therefore, Herz' hypothesis on the smallness of the contact area cannot be used. Fundamental equations were derived coinciding externally with the equation in the theory of a finite-span wing with unkown parameter. These equations are solved using Multhopp's well-known technique, and numerical calculations are performed in specific examples.

  1. Lettuce contact allergy.

    PubMed

    Paulsen, Evy; Andersen, Klaus E

    2016-02-01

    Lettuce (Lactuca sativa L.) and its varieties are important vegetable crops worldwide. They are also well-known, rarely reported, causes of contact allergy. As lettuce allergens and extracts are not commercially available, the allergy may be underdiagnosed. The aims of this article are to present new data on lettuce contact allergy and review the literature. Lettuce is weakly allergenic, and occupational cases are mainly reported. Using aimed patch testing in Compositae-allergic patients, two recent Danish studies showed prevalence rates of positive lettuce reactions of 11% and 22%. The majority of cases are non-occupational, and may partly be caused by cross-reactivity. The sesquiterpene lactone mix seems to be a poor screening agent for lettuce contact allergy, as the prevalence of positive reactions is significantly higher in non-occupationally sensitized patients. Because of the easy degradability of lettuce allergens, it is recommended to patch test with freshly cut lettuce stem and supplement this with Compositae mix. As contact urticaria and protein contact dermatitis may present as dermatitis, it is important to perform prick-to-prick tests, and possibly scratch patch tests as well. Any person who is occupationally exposed to lettuce for longer periods, especially atopics, amateur gardeners, and persons keeping lettuce-eating pets, is potentially at risk of developing lettuce contact allergy. PMID:26289653

  2. Contact micromechanics in granular media with clay

    SciTech Connect

    Ita, S.L.

    1994-08-01

    Many granular materials, including sedimentary rocks and soils, contain clay particles in the pores, grain contacts, or matrix. The amount and location of the clays and fluids can influence the mechanical and hydraulic properties of the granular material. This research investigated the mechanical effects of clay at grain-to-grain contacts in the presence of different fluids. Laboratory seismic wave propagation tests were conducted at ultrasonic frequencies using spherical glass beads coated with Montmorillonite clay (SWy-1) onto which different fluids were adsorbed. For all bead samples, seismic velocity increased and attenuation decreased as the contact stiffnesses increased with increasing stress demonstrating that grain contacts control seismic transmission in poorly consolidated and unconsolidated granular material. Coating the beads with clay added stiffness and introduced viscosity to the mechanical contact properties that increased the velocity and attenuation of the propagating seismic wave. Clay-fluid interactions were studied by allowing the clay coating to absorb water, ethyl alcohol, and hexadecane. Increasing water amounts initially increased seismic attenuation due to clay swelling at the contacts. Attenuation decreased for higher water amounts where the clay exceeded the plastic limit and was forced from the contact areas into the surrounding open pore space during sample consolidation. This work investigates how clay located at grain contacts affects the micromechanical, particularly seismic, behavior of granular materials. The need for this work is shown by a review of the effects of clays on seismic wave propagation, laboratory measurements of attenuation in granular media, and proposed mechanisms for attenuation in granular media.

  3. Radioactive Doses - Predicted and Actual - and Likely Health Effects.

    PubMed

    Nagataki, S; Takamura, N

    2016-04-01

    Five years have passed since the nuclear accident at Fukushima Daiichi Nuclear Power Stations on 11 March 2011. Here we refer to reports from international organisations as sources of predicted values obtained from environmental monitoring and dose estimation models, and reports from various institutes in Japan are used as sources of individual actual values. The World Health Organization, based on information available up to 11 September 2011 (and published in 2012), reported that characteristic effective doses in the first year after the accident, to all age groups, were estimated to be in the 10-50 mSv dose band in example locations in evacuation areas. Estimated characteristic thyroid doses to infants in Namie Town were within the 100-200 mSv dose band. A report from the United Nations Scientific Committee on the Effects of Atomic Radiation published in 2014 shows that the effective dose received by adults in evacuation areas during the first year after the accident was 1.1-13 mSv. The absorbed dose to the thyroid in evacuated settlements was 7.2-35 mSv in adults and 15-83 mSv in 1-year-old infants. Individual external radiation exposure in the initial 4 months after the accident, estimated by superimposing individual behaviour data on to a daily dose rate map, was less than 3 mSv in 93.9% of residents (maximum 15 mSv) in evacuation areas. Actual individual thyroid equivalent doses were less than 15 mSv in 98.8% of children (maximum 25 mSv) in evacuation areas. When uncertainty exists in dose estimation models, it may be sensible to err on the side of caution, and final estimated doses are often much greater than actual radiation doses. However, overestimation of the dose at the time of an accident has a great influence on the psychology of residents. More than 100 000 residents have not returned to the evacuation areas 5 years after the Fukushima accident because of the social and mental effects during the initial period of the disaster. Estimates of

  4. Experiments on thermal contact conductance between metals below 100 K

    NASA Astrophysics Data System (ADS)

    Choi, Yeon Suk; Kim, Myung Su

    2014-01-01

    The thermal contact conductance is one of the important components in heat transfer mechanism. The accurate estimation of thermal contact conductance is necessary for the development of a conduction-cooled superconducting magnet system because the metallic materials are thermally connected to the refrigerator or heat sink to cool the superconducting magnet without cryogen. The contact resistance occurs at the interface between metals and the amount of conductance can be affected by various factors, such as surface roughness, contact area, and contact pressure. In the superconducting magnet system, there are several metal components in contact with each other for cooling magnet as well as supplying current to the magnet. Therefore, a temperature gradient exists between superconducting magnet and cryocooler. In this study, we have developed the thermal contact conductance measurement system and used the steady state method to measure the thermal conductance between metals. The effects of temperature, contact pressure and interfacial materials on the thermal contact conductance are also discussed.

  5. Metal contact reliability of RF MEMS switches

    NASA Astrophysics Data System (ADS)

    Ma, Qing; Tran, Quan; Chou, Tsung-Kuan A.; Heck, John; Bar, Hanan; Kant, Rishi; Rao, Valluri

    2007-01-01

    and smaller real contact areas at a given contact force. Contact reliability issues could also be tackled by improving mechanical designs. A novel collapsing switch capable of generating large contact forces (>300μN) was shown to be less vulnerable to contamination and stiction.

  6. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 10 2012-01-01 2012-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  7. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 10 2014-01-01 2014-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  8. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 10 2013-01-01 2013-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  9. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 10 2011-01-01 2011-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  10. 7 CFR 1437.101 - Actual production history.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 10 2010-01-01 2010-01-01 false Actual production history. 1437.101 Section 1437.101... Determining Yield Coverage Using Actual Production History § 1437.101 Actual production history. Actual production history (APH) is the unit's record of crop yield by crop year for the APH base period. The...

  11. What Galvanic Vestibular Stimulation Actually Activates

    PubMed Central

    Curthoys, Ian S.; MacDougall, Hamish Gavin

    2012-01-01

    In a recent paper in Frontiers Cohen et al. (2012) asked “What does galvanic vestibular stimulation actually activate?” and concluded that galvanic vestibular stimulation (GVS) causes predominantly otolithic behavioral responses. In this Perspective paper we show that such a conclusion does not follow from the evidence. The evidence from neurophysiology is very clear: galvanic stimulation activates primary otolithic neurons as well as primary semicircular canal neurons (Kim and Curthoys, 2004). Irregular neurons are activated at lower currents. The answer to what behavior is activated depends on what is measured and how it is measured, including not just technical details, such as the frame rate of video, but the exact experimental context in which the measurement took place (visual fixation vs total darkness). Both canal and otolith dependent responses are activated by GVS. PMID:22833733

  12. MODIS Solar Diffuser: Modelled and Actual Performance

    NASA Technical Reports Server (NTRS)

    Waluschka, Eugene; Xiong, Xiao-Xiong; Esposito, Joe; Wang, Xin-Dong; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument's solar diffuser is used in its radiometric calibration for the reflective solar bands (VIS, NTR, and SWIR) ranging from 0.41 to 2.1 micron. The sun illuminates the solar diffuser either directly or through a attenuation screen. The attenuation screen consists of a regular array of pin holes. The attenuated illumination pattern on the solar diffuser is not uniform, but consists of a multitude of pin-hole images of the sun. This non-uniform illumination produces small, but noticeable radiometric effects. A description of the computer model used to simulate the effects of the attenuation screen is given and the predictions of the model are compared with actual, on-orbit, calibration measurements.

  13. Fractal prediction model of thermal contact conductance of rough surfaces

    NASA Astrophysics Data System (ADS)

    Ji, Cuicui; Zhu, Hua; Jiang, Wei

    2013-01-01

    The thermal contact conductance problem is an important issue in studying the heat transfer of engineering surfaces, which has been widely studied since last few decades, and for predicting which many theoretical models have been established. However, the models which have been existed are lack of objectivity due to that they are mostly studied based on the statistical methodology characterization for rough surfaces and simple partition for the deformation formats of contact asperity. In this paper, a fractal prediction model is developed for the thermal contact conductance between two rough surfaces based on the rough surface being described by three-dimensional Weierstrass and Mandelbrot fractal function and assuming that there are three kinds of asperity deformation modes: elastic, elastoplastic and fully plastic. Influences of contact load and contact area as well as fractal parameters and material properties on the thermal contact conductance are investigated by using the presented model. The investigation results show that the thermal contact conductance increases with the increasing of the contact load and contact area. The larger the fractal dimension, or the smaller the fractal roughness, the larger the thermal contact conductance is. The thermal contact conductance increases with decreasing the ratio of Young's elastic modulus to the microhardness. The results obtained indicate that the proposed model can effectively predict the thermal contact conductance at the interface, which provide certain reference to the further study on the issue of heat transfer between contact surfaces.

  14. Electronic transport through nanotube contacts and devices

    NASA Astrophysics Data System (ADS)

    Buia, Calin Ioan

    2003-10-01

    Carbon nanotubes are materials with amazing mechanical and electronic properties, which makes them suitable for building nanoscale electronic devices and circuits. However, their electronic transport properties are not yet fully understood. In this study we aim to investigate the electronic transport through nanotube/nanotube contacts. Our calculations are based on Land auer-Buttiker formalism. The transmission function is computed using a Green's functions technique and a tight-binding hamiltonian. Two types of geometries are considered: parallel contact and concentric contact. Additionally we analyze the behavior of a nanotube Y-junction. We find that out of all the properties of individual nanotubes, chirality and symmetry have the most important effect on the electronic transport. As a rule, armchair/armchair and metallic zigzag/zigzag contacts show the best conduction. This is explained by the perfect in-registry atomic arrangement they can provide. The contact length and the local arrangement of the atoms in the contact area are factors that further influence the conductance. We found that in optimal conditions (i.e. in-registry atomic arrangement), a contact length of ˜10 nm is enough to achieve the same conductance as a perfect nanotube. Beyond that the conductance is modulated by quantum interference effects, due to the formation of a resonant cavity in the contact area. For concentric contacts, the states between which the electron hops when passing from one tube to the other must have compatible rotational symmetries, otherwise, the corresponding conduction channel will be suppressed. This results can be used to predict the electronic transport through various setups, including nanotube bundles and multiwall nanotubes.

  15. Contact Lenses for Vision Correction

    MedlinePlus

    ... Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd Reviewed by: Brenda ... on the surface of the eye. They correct vision like eyeglasses do and are safe when used ...

  16. Contact binary stars

    NASA Astrophysics Data System (ADS)

    Mochnacki, S. W.

    1981-04-01

    Densities, corrected primary colors, minimum periods, inferred masses, luminosities, and specific angular momenta are computed from data on 37 W Ursae Majoris systems. A-type systems, having lower densities and angular momenta than the W-type systems, are shown to be evolved, and a new class of contact binary is identified, the OO Aquilae systems, whose members have evolved into contact. Evolutionary grids based on the contact condition agree with observation, except in that the evolved A-type systems have lost more angular momentum than predicted by gravitational radiation alone. This is accounted for by stellar wind magnetic braking, which is shown to be effective on a shorter time scale and to be important in other kinds of binaries containing a cool, tidally coupled component.

  17. Shoe allergic contact dermatitis.

    PubMed

    Matthys, Erin; Zahir, Amir; Ehrlich, Alison

    2014-01-01

    Foot dermatitis is a widespread condition, affecting men and women of all ages. Because of the location, this condition may present as a debilitating problem to those who have it. Allergic contact dermatitis involving the feet is frequently due to shoes or socks. The allergens that cause shoe dermatitis can be found in any constituent of footwear, including rubber, adhesives, leather, dyes, metals, and medicaments. The goal of treatment is to identify and minimize contact with the offending allergen(s). The lack of product information released from shoe manufacturers and the continually changing trends in footwear present a challenge in treating this condition. The aim of this study is to review the current literature on allergic contact shoe dermatitis; clinical presentation, allergens, patch testing, and management will be discussed. PubMed and MEDLINE databases were used for the search, with a focus on literature updates from the last 15 years. PMID:25000234

  18. Contact sensitization in children.

    PubMed

    Manzini, B M; Ferdani, G; Simonetti, V; Donini, M; Seidenari, S

    1998-01-01

    Our study concerns contact sensitization in children, the frequency of which is still debated in the literature, even though specific reports are increasing. During a 7 year period (1988-1994) 670 patients, 6 months to 12 years of age, were patch tested with the European standard series, integrated with 24 haptens, at the same concentrations as for adults. We observed positive results in 42% of our patients. Thimerosal, nickel sulfate, Kathon CG, fragrance mix, neomycin, wool alcohols, and ammoniated mercury induced most of the positive responses. The highest sensitization rate was found in children from 0 to 3 years of age. Comments on main positive haptens are reported. Seventy-seven percent of our sensitized patients were atopics, suggesting that atopy represents a predisposing factor for contact hypersensitivity. Patch testing represents a useful diagnostic procedure for the definition of childhood eczematous dermatitis and for the identification of agents inducing contact sensitization which is frequently associated with atopic dermatitis. PMID:9496796

  19. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo (Inventor)

    1988-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on a normal probability chart, enables prediction of the yield of good integrated circuits from the wafer.

  20. Cross-contact chain

    NASA Technical Reports Server (NTRS)

    Lieneweg, U. (Inventor)

    1986-01-01

    A system is provided for use with wafers that include multiple integrated circuits that include two conductive layers in contact at multiple interfaces. Contact chains are formed beside the integrated circuits, each contact chain formed of the same two layers as the circuits, in the form of conductive segments alternating between the upper and lower layers and with the ends of the segments connected in series through interfaces. A current source passes a current through the series-connected segments, by way of a pair of current tabs connected to opposite ends of the series of segments. While the current flows, voltage measurements are taken between each of a plurality of pairs of voltage tabs, the two tabs of each pair connected to opposite ends of an interface that lies along the series-connected segments. A plot of interface conductances on normal probability chart enables prediction of the yield of good integrated circuits from the wafer.

  1. Improved contact predictions using the recognition of protein like contact patterns.

    PubMed

    Skwark, Marcin J; Raimondi, Daniele; Michel, Mirco; Elofsson, Arne

    2014-11-01

    Given sufficient large protein families, and using a global statistical inference approach, it is possible to obtain sufficient accuracy in protein residue contact predictions to predict the structure of many proteins. However, these approaches do not consider the fact that the contacts in a protein are neither randomly, nor independently distributed, but actually follow precise rules governed by the structure of the protein and thus are interdependent. Here, we present PconsC2, a novel method that uses a deep learning approach to identify protein-like contact patterns to improve contact predictions. A substantial enhancement can be seen for all contacts independently on the number of aligned sequences, residue separation or secondary structure type, but is largest for β-sheet containing proteins. In addition to being superior to earlier methods based on statistical inferences, in comparison to state of the art methods using machine learning, PconsC2 is superior for families with more than 100 effective sequence homologs. The improved contact prediction enables improved structure prediction. PMID:25375897

  2. Caustic-Side Solvent Extraction: Prediction of Cesium Extraction for Actual Wastes and Actual Waste Simulants

    SciTech Connect

    Delmau, L.H.; Haverlock, T.J.; Sloop, F.V., Jr.; Moyer, B.A.

    2003-02-01

    This report presents the work that followed the CSSX model development completed in FY2002. The developed cesium and potassium extraction model was based on extraction data obtained from simple aqueous media. It was tested to ensure the validity of the prediction for the cesium extraction from actual waste. Compositions of the actual tank waste were obtained from the Savannah River Site personnel and were used to prepare defined simulants and to predict cesium distribution ratios using the model. It was therefore possible to compare the cesium distribution ratios obtained from the actual waste, the simulant, and the predicted values. It was determined that the predicted values agree with the measured values for the simulants. Predicted values also agreed, with three exceptions, with measured values for the tank wastes. Discrepancies were attributed in part to the uncertainty in the cation/anion balance in the actual waste composition, but likely more so to the uncertainty in the potassium concentration in the waste, given the demonstrated large competing effect of this metal on cesium extraction. It was demonstrated that the upper limit for the potassium concentration in the feed ought to not exceed 0.05 M in order to maintain suitable cesium distribution ratios.

  3. Toward patient-specific articular contact mechanics

    PubMed Central

    Ateshian, Gerard A.; Henak, Corinne R.; Weiss, Jeffrey A.

    2015-01-01

    The mechanics of contacting cartilage layers is fundamentally important to understanding the development, homeostasis and pathology of diarthrodial joints. Because of the highly nonlinear nature of both the materials and the contact problem itself, numerical methods such as the finite element method are typically incorporated to obtain solutions. Over the course of five decades, we have moved from an initial qualitative understanding of articular cartilage material behavior to the ability to perform complex, three-dimensional contact analysis, including multiphasic material representations. This history includes the development of analytical and computational contact analysis methods that now provide the ability to perform highly nonlinear analyses. Numerical implementations of contact analysis based on the finite element method are rapidly advancing and will soon enable patient-specific analysis of joint contact mechanics using models based on medical image data. In addition to contact stress on the articular surfaces, these techniques can predict variations in strain and strain through the cartilage layers, providing the basis to predict damage and failure. This opens up exciting areas for future research and application to patient-specific diagnosis and treatment planning applied to a variety of pathologies that affect joint function and cartilage homeostasis. PMID:25698236

  4. Numerical analysis of human dental occlusal contact

    NASA Astrophysics Data System (ADS)

    Bastos, F. S.; Las Casas, E. B.; Godoy, G. C. D.; Meireles, A. B.

    2010-06-01

    The purpose of this study was to obtain real contact areas, forces, and pressures acting on human dental enamel as a function of the nominal pressure during dental occlusal contact. The described development consisted of three steps: characterization of the surface roughness by 3D contact profilometry test, finite element analysis of micro responses for each pair of main asperities in contact, and homogenization of macro responses using an assumed probability density function. The inelastic deformation of enamel was considered, adjusting the stress-strain relationship of sound enamel to that obtained from instrumented indentation tests conducted with spherical tip. A mechanical part of the static friction coefficient was estimated as the ratio between tangential and normal components of the overall resistive force, resulting in μd = 0.057. Less than 1% of contact pairs reached the yield stress of enamel, indicating that the occlusal contact is essentially elastic. The micro-models indicated an average hardness of 6.25GPa, and the homogenized result for macroscopic interface was around 9GPa. Further refinements of the methodology and verification using experimental data can provide a better understanding of processes related to contact, friction and wear of human tooth enamel.

  5. Coupled thermoelastic analysis of fretting contacts

    NASA Astrophysics Data System (ADS)

    Ganapathy, Harish

    Fretting fatigue is the contact phenomenon occurring when two bodies in contact experience oscillatory loads. The surface tribology and contact stress evolution in a fretting contact has been studied using coupled thermoelastic analysis. Both, an aluminum and titanium alloy have been studied. Full-field real-time in-situ temperature maps of the contact region and its vicinity have been obtained using a multi-element infrared camera. The distinguishing features of the contact including the sliding regime, partial slip contact, bulk stress effects, boundary conditions effects etc. have been successfully captured using temperature measurement of the order of millikelvin. The coupled thermoclastic response of aluminum and titanium alloy has been successfully characterized, including the mean stress effect. A full coupled thermoelastic finite element model with Coulomb friction, frictional heating and gap conductance, has been used to predict the experimental temperatures. Changes in loads and changes in the coefficient of friction produce changes in different areas of the temperature field. The coupled thermoelastic effect may be used as a powerful tool to guide the march towards the complete understanding of the phenomenon of fretting. The method has been successfully used to guide the finite element analysis of a lap joint specimen.

  6. Physical and reliability issues in MEMS microrelays with gold contacts

    NASA Astrophysics Data System (ADS)

    Lafontan, Xavier; Pressecq, Francis; Perez, Guy; Dufaza, Christian; Karam, Jean Michel

    2001-10-01

    This paper presents the work we have done on micro-relays with gold micro-contacts in MUMPs. Firstly, the theoretical physical principles of MEMS micro-relay are described. This study is divided in two parts: the micro-contact and the micro-actuator. The micro-contact part deals with resistance of constriction, contact area, adhesion, arcing and wear. Whereas the micro-actuator part describes general principles, contact force, restoring force and actuator reliability. Then, in a second part, an innovative electrostatic relay design in MUMPs is presented. The concept, the implementation and the final realization are discussed. Then, in the third part, characterization results are reported. This part particularly focuses on the micro-contact study. Conduction mode, contact area, mechanical and thermal deformation, and adhesion energies are presented.

  7. Identity Theft: A Study in Contact Centres

    NASA Astrophysics Data System (ADS)

    Moir, Iain; Weir, George R. S.

    This paper explores the recent phenomenon of identity theft. In particular, it examines the contact centre environment as a mechanism for this to occur. Through a survey that was conducted amongst forty-five contact centre workers in the Glasgow area we determined that contact centres can and do provide a mechanism for identity theft. Specifically, we found a particularly high incidence of agents who had previously dealt with phone calls that they considered suspicious. Furthermore, there are agents within such environments who have previously been offered money in exchange for customers' details, or who know of fellow workers who received such offers. Lastly, we identify specific practices within contact centres that may contribute to the likelihood of identity theft.

  8. Thermal contact conductance for cylindrical and spherical contacts

    NASA Astrophysics Data System (ADS)

    Sunil Kumar, S.; Abilash, P. M.; Ramamurthi, K.

    A prediction methodology based on Monte-Carlo simulation model, developed for flat conforming surfaces in contact, is modified and extended to predict contact conductance between curvilinear surfaces like cylinders and spheres. Experiments are also conducted in vacuum for the measurement of contact conductance between stainless steel and aluminium cylindrical contacts and stainless steel spherical contacts over a range of contact pressures. The contact conductance between cylindrical and spherical bodies is, in general, about an order of magnitude lower than for flat surfaces in contact. Increase of surface roughness and decrease in contact pressure lowers the contact conductance. However, the influence of these parameters is larger than those obtained for flat surfaces. The prediction for different parametric conditions agree closely with those measured in the experiments.

  9. Contact: Releasing the news

    NASA Astrophysics Data System (ADS)

    Pinotti, Roberto

    The problem of mass behavior after man's future contacts with other intelligences in the universe is not only a challenge for social scientists and political leaders all over the world, but also a cultural time bomb as well. In fact, since the impact of CETI (Contact with Extraterrestrial Intelligence) on human civilization, with its different cultures, might cause a serious socio-anthropological shock, a common and predetermined worldwide strategy is necessary in releasing the news after the contact, in order to keep possible manifestations of fear, panic and hysteria under control. An analysis of past studies in this field and of parallel historical situations as analogs suggests a definite "authority crisis" in the public as a direct consequence of an unexpected release of the news, involving a devastating "chain reaction" process (from both the psychological and sociological viewpoints) of anomie and maybe the collapse of today's society. The only way to prevent all this is to prepare the world's public opinion concerning contact before releasing the news, and to develop a long-term strategy through the combined efforts of scientists, political leaders, intelligence agencies and the mass media, in order to create the cultural conditions in which a confrontation with ETI won't affect mankind in a traumatic way. Definite roles and tasks in this multi-level model are suggested.

  10. [Current contact allergens].

    PubMed

    Geier, J; Uter, W; Lessmann, H; Schnuch, A

    2011-10-01

    Ever-changing exposure to contact allergens, partly due to statutory directives (e.g. nickel, chromate, methyldibromo glutaronitrile) or recommendations from industrial associations (e.g. hydroxyisohexyl 3-cyclohexene carboxaldehyde), requires on-going epidemiologic surveillance of contact allergy. In this paper, the current state with special focus in fragrances and preservatives is described on the basis of data of the Information Network of Departments of Dermatology (IVDK) of the year 2010. In 2010, 12,574 patients were patch tested in the dermatology departments belonging to the IVDK. Nickel is still the most frequent contact allergen. However the continuously improved EU nickel directive already has some beneficial effect; sensitization frequency in young women is dropping. In Germany, chromate-reduced cement has been in use now for several years, leading to a decline in chromate sensitization in brick-layers. Two fragrance mixes are part of the German baseline series; they are still relevant. The most important fragrances in these mixes still are oak moss absolute and hydroxyisohexyl 3-cyclohexene carboxaldehyde. However, in relation to these leading allergens, sensitization frequency to other fragrances contained in the mixes seems to be increasing. Among the preservatives, MCI/MI has not lost its importance as contact allergen, in contrast to MDBGN. Sources of MCI/MI sensitization obviously are increasingly found in occupational context. Methylisothiazolinone is a significant allergen in occupational settings, and less frequently in body care products. PMID:21901563

  11. Thermal Contact Conductance

    NASA Technical Reports Server (NTRS)

    Salerno, Louis J.; Kittel, Peter

    1997-01-01

    The performance of cryogenic instruments is often a function of their operating temperature. Thus, designers of cryogenic instruments often are required to predict the operating temperature of each instrument they design. This requires accurate thermal models of cryogenic components which include the properties of the materials and assembly techniques used. When components are bolted or otherwise pressed together, a knowledge of the thermal performance of such joints are also needed. In some cases, the temperature drop across these joints represents a significant fraction of the total temperature difference between the instrument and its cooler. While extensive databases exist on the thermal properties of bulk materials, similar databases for pressed contacts do not. This has often lead to instrument designs that avoid pressed contacts or to the over-design of such joints at unnecessary expense. Although many people have made measurements of contact conductances at cryogenic temperatures, this data is often very narrow in scope and even more often it has not been published in an easily retrievable fashion, if published at all. This paper presents a summary of the limited pressed contact data available in the literature.

  12. Multigrid contact detection method

    NASA Astrophysics Data System (ADS)

    He, Kejing; Dong, Shoubin; Zhou, Zhaoyao

    2007-03-01

    Contact detection is a general problem of many physical simulations. This work presents a O(N) multigrid method for general contact detection problems (MGCD). The multigrid idea is integrated with contact detection problems. Both the time complexity and memory consumption of the MGCD are O(N) . Unlike other methods, whose efficiencies are influenced strongly by the object size distribution, the performance of MGCD is insensitive to the object size distribution. We compare the MGCD with the no binary search (NBS) method and the multilevel boxing method in three dimensions for both time complexity and memory consumption. For objects with similar size, the MGCD is as good as the NBS method, both of which outperform the multilevel boxing method regarding memory consumption. For objects with diverse size, the MGCD outperform both the NBS method and the multilevel boxing method. We use the MGCD to solve the contact detection problem for a granular simulation system based on the discrete element method. From this granular simulation, we get the density property of monosize packing and binary packing with size ratio equal to 10. The packing density for monosize particles is 0.636. For binary packing with size ratio equal to 10, when the number of small particles is 300 times as the number of big particles, the maximal packing density 0.824 is achieved.

  13. Compact contacting device

    NASA Technical Reports Server (NTRS)

    Acharya, Arun (Inventor); Gottzmann, Christian F. (Inventor); Lockett, Michael J. (Inventor); Schneider, James S. (Inventor); Victor, Richard A. (Inventor); Zawierucha, Robert (Inventor)

    1994-01-01

    An apparatus comprising a rotatable mass of structured packing for mass or heat transfer between two contacting fluids of different densities wherein the packing mass is made up of corrugated sheets of involute shape relative to the axis of the packing mass and form a logarithmic spiral curved counter to the direction of rotation.

  14. Religious Allergic Contact Dermatitis.

    PubMed

    Goldenberg, Alina; Matiz, Catalina; Eichenfield, Lawrence F

    2015-01-01

    Henna, derived from a combination of natural leaves and coloring additives, is a common decorative dye traditionally used in many Islamic religious celebrations. Para-phenylenediamine (PPD), a major component of black henna tattoo, is a strong sensitizer and common allergen. We report a case of severe connubial allergic contact dermatitis after black henna heterotransfer in a girl. PMID:25968562

  15. Have Confidence in Contact

    ERIC Educational Resources Information Center

    Crisp, Richard J.; Turner, Rhiannon N.

    2010-01-01

    In an article in the May-June 2009 "American Psychologist," we discussed a new approach to reducing prejudice and encouraging more positive intergroup relations (Crisp & Turner, 2009). We named the approach imagined intergroup contact and defined it as "the mental simulation of a social interaction with a member or members of an outgroup category"…

  16. Measurement of effective bulk and contact resistance of gas diffusion layer under inhomogeneous compression - Part II: Thermal conductivity

    NASA Astrophysics Data System (ADS)

    Roy Chowdhury, Prabudhya; Vikram, Ajit; Phillips, Ryan K.; Hoorfar, Mina

    2016-07-01

    The gas diffusion layer (GDL) is a thin porous layer sandwiched between a bipolar plate (BPP) and a catalyst coated membrane in a fuel cell. Besides providing passage for water and gas transport from and to the catalyst layer, it is responsible for electron and heat transfer from and to the BPP. In this paper, a method has been developed to measure the GDL bulk thermal conductivity and the contact resistance at the GDL/BPP interface under inhomogeneous compression occurring in an actual fuel cell assembly. Toray carbon paper GDL TGP-H-060 was tested under a range of compression pressure of 0.34 to 1.71 MPa. The results showed that the thermal contact resistance decreases non-linearly (from 3.8 × 10-4 to 1.17 × 10-4 Km2 W-1) with increasing pressure due to increase in microscopic contact area between the GDL and BPP; while the effective bulk thermal conductivity increases (from 0.56 to 1.42 Wm-1 K-1) with increasing the compression pressure. The thermal contact resistance was found to be greater (by a factor of 1.6-2.8) than the effective bulk thermal resistance for all compression pressure ranges applied here. This measurement technique can be used to identify optimum GDL based on minimum bulk and contact resistances measured under inhomogeneous compression.

  17. Exploring the Nature of Contact Freezing

    NASA Astrophysics Data System (ADS)

    Kiselev, A. A.; Hoffmann, N.; Duft, D.; Leisner, T.

    2012-12-01

    The freezing of supercooled water droplets upon contact with aerosol particles (contact nucleation of ice) is the least understood mechanism of ice formation in atmospheric clouds. Although experimental evidences suggest that some aerosols can be better IN in the contact than in the immersion mode (that is, triggering ice nucleation at higher temperature), no final explanation of this phenomena currently exists. On the other hand, the contact freezing is believed to be responsible for the enhanced rate of secondary ice formation occasionally observed in LIDAR measurements in the cold mixed phase clouds. Recently we have been able to show that the freezing of supercooled droplets electrodynamically levitated in the laminar flow containing mineral dust particles (kaolinite) is a process solely governed by a rate of collisions between the supercooled droplet and the aerosol particles. We have shown that the probability of droplet freezing on a single contact with aerosol particle may differ over an order of magnitude for kaolinite particles having different genesis and morphology. In this presentation we extend the study of contact nucleation of ice and compare the IN efficiency measured for DMA-selected kaolinite, illite and hematite particles. We show that the freezing probability increases towards unity as the temperature decreases and discuss the functional form of this temperature dependence. We explore the size dependence of the contact freezing probability and show that it scales with the surface area of the particles, thus resembling the immersion freezing behavior. However, for all minerals investigated so far, the contact freezing has been shown to dominate over immersion freezing on the short experimental time scales. Finally, based on the combined ESEM and electron microprobe analysis, we discuss the significance of particle morphology and variability of chemical composition on its IN efficiency in contact mode.

  18. Consequences of Predicted or Actual Asteroid Impacts

    NASA Astrophysics Data System (ADS)

    Chapman, C. R.

    2003-12-01

    Earth impact by an asteroid could have enormous physical and environmental consequences. Impactors larger than 2 km diameter could be so destructive as to threaten civilization. Since such events greatly exceed any other natural or man-made catastrophe, much extrapolation is necessary just to understand environmental implications (e.g. sudden global cooling, tsunami magnitude, toxic effects). Responses of vital elements of the ecosystem (e.g. agriculture) and of human society to such an impact are conjectural. For instance, response to the Blackout of 2003 was restrained, but response to 9/11 terrorism was arguably exaggerated and dysfunctional; would society be fragile or robust in the face of global catastrophe? Even small impacts, or predictions of impacts (accurate or faulty), could generate disproportionate responses, especially if news media reports are hyped or inaccurate or if responsible entities (e.g. military organizations in regions of conflict) are inadequately aware of the phenomenology of small impacts. Asteroid impact is the one geophysical hazard of high potential consequence with which we, fortunately, have essentially no historical experience. It is thus important that decision makers familiarize themselves with the hazard and that society (perhaps using a formal procedure, like a National Academy of Sciences study) evaluate the priority of addressing the hazard by (a) further telescopic searches for dangerous but still-undiscovered asteroids and (b) development of mitigation strategies (including deflection of an oncoming asteroid and on- Earth civil defense). I exemplify these issues by discussing several representative cases that span the range of parameters. Many of the specific physical consequences of impact involve effects like those of other geophysical disasters (flood, fire, earthquake, etc.), but the psychological and sociological aspects of predicted and actual impacts are distinctive. Standard economic cost/benefit analyses may not

  19. Contact Graph Routing

    NASA Technical Reports Server (NTRS)

    Burleigh, Scott C.

    2011-01-01

    Contact Graph Routing (CGR) is a dynamic routing system that computes routes through a time-varying topology of scheduled communication contacts in a network based on the DTN (Delay-Tolerant Networking) architecture. It is designed to enable dynamic selection of data transmission routes in a space network based on DTN. This dynamic responsiveness in route computation should be significantly more effective and less expensive than static routing, increasing total data return while at the same time reducing mission operations cost and risk. The basic strategy of CGR is to take advantage of the fact that, since flight mission communication operations are planned in detail, the communication routes between any pair of bundle agents in a population of nodes that have all been informed of one another's plans can be inferred from those plans rather than discovered via dialogue (which is impractical over long one-way-light-time space links). Messages that convey this planning information are used to construct contact graphs (time-varying models of network connectivity) from which CGR automatically computes efficient routes for bundles. Automatic route selection increases the flexibility and resilience of the space network, simplifying cross-support and reducing mission management costs. Note that there are no routing tables in Contact Graph Routing. The best route for a bundle destined for a given node may routinely be different from the best route for a different bundle destined for the same node, depending on bundle priority, bundle expiration time, and changes in the current lengths of transmission queues for neighboring nodes; routes must be computed individually for each bundle, from the Bundle Protocol agent's current network connectivity model for the bundle s destination node (the contact graph). Clearly this places a premium on optimizing the implementation of the route computation algorithm. The scalability of CGR to very large networks remains a research topic

  20. Thermal conductance of carbon nanotube contacts: Molecular dynamics simulations and general description of the contact conductance

    NASA Astrophysics Data System (ADS)

    Salaway, Richard N.; Zhigilei, Leonid V.

    2016-07-01

    The contact conductance of carbon nanotube (CNT) junctions is the key factor that controls the collective heat transfer through CNT networks or CNT-based materials. An improved understanding of the dependence of the intertube conductance on the contact structure and local environment is needed for predictive computational modeling or theoretical description of the effective thermal conductivity of CNT materials. To investigate the effect of local structure on the thermal conductance across CNT-CNT contact regions, nonequilibrium molecular dynamics (MD) simulations are performed for different intertube contact configurations (parallel fully or partially overlapping CNTs and CNTs crossing each other at different angles) and local structural environments characteristic of CNT network materials. The results of MD simulations predict a stronger CNT length dependence present over a broader range of lengths than has been previously reported and suggest that the effect of neighboring junctions on the conductance of CNT-CNT junctions is weak and only present when the CNTs that make up the junctions are within the range of direct van der Waals interaction with each other. A detailed analysis of the results obtained for a diverse range of intertube contact configurations reveals a nonlinear dependence of the conductance on the contact area (or number of interatomic intertube interactions) and suggests larger contributions to the conductance from areas of the contact where the density of interatomic intertube interactions is smaller. An empirical relation accounting for these observations and expressing the conductance of an arbitrary contact configuration through the total number of interatomic intertube interactions and the average number of interatomic intertube interactions per atom in the contact region is proposed. The empirical relation is found to provide a good quantitative description of the contact conductance for various CNT configurations investigated in the MD

  1. Contact dynamics math model

    NASA Technical Reports Server (NTRS)

    Glaese, John R.; Tobbe, Patrick A.

    1986-01-01

    The Space Station Mechanism Test Bed consists of a hydraulically driven, computer controlled six degree of freedom (DOF) motion system with which docking, berthing, and other mechanisms can be evaluated. Measured contact forces and moments are provided to the simulation host computer to enable representation of orbital contact dynamics. This report describes the development of a generalized math model which represents the relative motion between two rigid orbiting vehicles. The model allows motion in six DOF for each body, with no vehicle size limitation. The rotational and translational equations of motion are derived. The method used to transform the forces and moments from the sensor location to the vehicles' centers of mass is also explained. Two math models of docking mechanisms, a simple translational spring and the Remote Manipulator System end effector, are presented along with simulation results. The translational spring model is used in an attempt to verify the simulation with compensated hardware in the loop results.

  2. Simulating Contact Binaries

    NASA Astrophysics Data System (ADS)

    Kadam, Kundan; Clayton, Geoffrey C.; Frank, Juhan; Tohline, Joel E.; Staff, Jan E.; Motl, Patrick M.; Marcello, Dominic

    2014-06-01

    About one in every 150 stars is a contact binary system of WUMa type and it was thought for a long time that such a binary would naturally proceed towards merger, forming a single star. In September 2008 such a merger was observed in the eruption of a “red nova", V1309 Sco. We are developing a hydrodynamics simulation for contact binaries using Self Consistent Field (SCF) techniques, so that their formation, structural, and merger properties could be studied. This model can also be used to probe the stability criteria such as the large-scale equatorial circulations and the minimum mass ratio. We also plan to generate light curves from the simulation data in order to compare with the observed case of V1309 Sco. A comparison between observations and simulations will help us better understand the nova-like phenomena of stellar mergers.

  3. Carrier Selective, Passivated Contacts for High Efficiency Silicon Solar Cells based on Transparent Conducting Oxides

    DOE PAGESBeta

    Young, David L.; Nemeth, William; Grover, Sachit; Norman, Andrew; Yuan, Hao-Chih; Lee, Benjamin G.; LaSalvia, Vincenzo; Stradins, Paul

    2014-01-01

    We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO2 and transparent conducting oxide layers. High temperature silicon dioxide is grown on both surfaces of an n-type wafer to a thickness <50 Å, followed by deposition of tin-doped indium oxide (ITO) and a patterned metal contacting layer. As deposited, the thin-film stack has a very high J0,contact, and a non-ohmic, high contact resistance. However, after a forming gas anneal, the passivation quality and the contact resistivity improve significantly. The contacts are characterized by measuring the recombination parameter of the contact (J0,contact) and the specificmore » contact resistivity (ρcontact) using a TLM pattern. The best ITO/SiO2 passivated contact in this study has J0,contact = 92.5 fA/cm2 and ρcontact = 11.5 mOhm-cm2. These values are placed in context with other passivating contacts using an analysis that determines the ultimate efficiency and the optimal area fraction for contacts for a given set of (J0,contact, ρcontact) values. The ITO/SiO2 contacts are found to have a higher J0,contact, but a similar ρcontact compared to the best reported passivated contacts.« less

  4. Contact dermatitis in children

    PubMed Central

    2010-01-01

    Contact dermatitis in pediatric population is a common but (previously) under recognized disease. It is usually divided into the allergic and the irritant forms. The diagnosis is usually obtained with the patch test technique after conducting a thorough medical history and careful physical examination but patch testing in infants may be particularly difficult, and false-positive reactions may occur. This study also provides an overview of the most common allergens in pediatric population and discusses various therapeutic modalities. PMID:20205907

  5. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2014-02-11

    A method for producing a contact stress sensor that includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  6. Contact stress sensor

    DOEpatents

    Kotovsky, Jack

    2012-02-07

    A contact stress sensor includes one or more MEMS fabricated sensor elements, where each sensor element of includes a thin non-recessed portion, a recessed portion and a pressure sensitive element adjacent to the recessed portion. An electric circuit is connected to the pressure sensitive element. The circuit includes a thermal compensator and a pressure signal circuit element configured to provide a signal upon movement of the pressure sensitive element.

  7. Allergic Contact Dermatitis to Eye Drops

    PubMed Central

    Bhat, Yasmeen Jabeen; Zeerak, Sumaya; Hassan, Iffat

    2015-01-01

    Allergic contact dermatitis (ACD) occurs due to a milieu of allergens and involves different anatomical sites, including eyelids, and periorbital areas. Topically applied ophthalmic drugs are a potential cause of ACD of the periorbital region. Here we describe the report of a patient who developed ACD to eye drop preparations. PMID:26677304

  8. English in Albania: Contact and Convergence.

    ERIC Educational Resources Information Center

    Dushku, Silvana

    1998-01-01

    Gives an overview of the current status and usage of English in Albania, outlining the sociolinguistic context in which changes in usage have taken place. Evidence is presented of increasing contact areas of English and standard Albanian under the new, post-communist sociopolitical and economic circumstances. Attention is drawn to need for more…

  9. Intergenerational Contact: A Way to Counteract Ageism.

    ERIC Educational Resources Information Center

    Peacock, E. Winnifred; Talley, William M.

    1984-01-01

    Examines the problem of ageism and questions some sociocultural barriers and prevalent attitudes that promote such behavior. Benefits of intergenerational contact are emphasized. Discusses some means of bringing together age groups and describes some of the current projects in this area which have been successful. (JAC)

  10. Functional modular contact lens

    NASA Astrophysics Data System (ADS)

    Shum, Angela J.; Cowan, Melissa; Lähdesmäki, Ilkka; Lingley, Andrew; Otis, Brian; Parviz, Babak A.

    2009-08-01

    Tear fluid offers a potential route for non-invasive sensing of physiological parameters. Utilization of this potential depends on the ability to manufacture sensors that can be placed on the surface of the eye. A contact lens makes a natural platform for such sensors, but contact lens polymers present a challenge for sensor fabrication. This paper describes a microfabrication process for constructing sensors that can be integrated into the structure of a functional contact lens in the future. To demonstrate the capabilities of the process, an amperometric glucose sensor was fabricated on a polymer substrate. The sensor consists of platinum working and counter electrodes, as well as a region of indium-tin oxide (ITO) for glucose oxidase immobilization. An external silver-silver chloride electrode was used as the reference electrode during the characterization experiments. Sensor operation was validated by hydrogen peroxide measurements in the 10- 20 μM range and glucose measurements in the 0.125-20 mM range.

  11. Acrylate Systemic Contact Dermatitis.

    PubMed

    Sauder, Maxwell B; Pratt, Melanie D

    2015-01-01

    Acrylates, the 2012 American Contact Dermatitis Society allergen of the year, are found in a range of products including the absorbent materials within feminine hygiene pads. When fully polymerized, acrylates are nonimmunogenic; however, if not completely cured, the monomers can be potent allergens.A 28-year-old woman is presented, who had her teeth varnished with Isodan (Septodont, Saint-Maur-des-Fossés, France) containing HEMA (2-hydroxyethyl methacrylate) with no initial reaction. Approximately 1 month later, the patient developed a genital dermatitis secondary to her feminine hygiene pads. The initial reaction resolved, but 5 months later, the patient developed a systemic contact dermatitis after receiving a second varnishing.The patient was dramatically patch test positive to many acrylates. This case demonstrates a reaction to likely unpolymerized acrylates within a feminine hygiene pad, as well as broad cross-reactivity or cosensitivity to acrylates, and possibly a systemic contact dermatitis with systemic re-exposure to unpolymerized acrylates. PMID:26367207

  12. Pediatric contact dermatitis.

    PubMed

    Sharma, Vinod K; Asati, Dinesh P

    2010-01-01

    Allergic contact dermatitis (ACD) in children, until recently, was considered rare. ACD was considered as a disorder of the adult population and children were thought to be spared due to a lack of exposure to potential allergens and an immature immune system. Prevalence of ACD to even the most common allergens in children, like poison ivy and parthenium, is relatively rare as compared to adults. However, there is now growing evidence of contact sensitization of the pediatric population, and it begins right from early childhood, including 1-week-old neonates. Vaccinations, piercing, topical medicaments and cosmetics in younger patients are potential exposures for sensitization. Nickel is the most common sensitizer in almost all studies pertaining to pediatric contact dermatitis. Other common allergens reported are cobalt, fragrance mix, rubber, lanolin, thiomersol, neomycin, gold, mercapto mix, balsum of Peru and colophony. Different factors like age, sex, atopy, social and cultural practices, habit of parents and caregivers and geographic changes affect the patterns of ACD and their variable clinical presentation. Patch testing should be considered not only in children with lesions of a morphology suggestive of ACD, but in any child with dermatitis that is difficult to control. PMID:20826990

  13. Lubricant Rheology in Concentrated Contacts

    NASA Technical Reports Server (NTRS)

    Jacobson, B. O.

    1984-01-01

    Lubricant behavior in highly stressed situtations shows that a Newtonian model for lubricant rheology is insufficient for explanation of traction behavior. The oil film build up is predicted by using a Newtonian lubricant model except at high slide to roll ratios and at very high loads, where the nonNewtonian behavior starts to be important already outside the Hertzian contact area. Static and dynamic experiments are reported. In static experiments the pressure is applied to the lubricant more than a million times longer than in an EHD contact. Depending on the pressure-temperature history of the experiment the lubricant will become a crystallized or amorphous solid at high pressures. In dynamic experiments, the oil is in an amorphous solid state. Depending on the viscosity, time scale, elasticity of the oil and the bearing surfaces, the oil film pressure, shear strain rate and the type of lubricant, different properties of the oil are important for prediction of shear stresses in the oil. The different proposed models for the lubricant, which describe it to a Newtonian liquid, an elastic liquid, a plastic liquid and an elastic-plastic solid.

  14. Rough viscoelastic sliding contact: Theory and experiments

    NASA Astrophysics Data System (ADS)

    Carbone, G.; Putignano, C.

    2014-03-01

    In this paper, we show how the numerical theory introduced by the authors [Carbone and Putignano, J. Mech. Phys. Solids 61, 1822 (2013), 10.1016/j.jmps.2013.03.005] can be effectively employed to study the contact between viscoelastic rough solids. The huge numerical complexity is successfully faced up by employing the adaptive nonuniform mesh developed by the authors in Putignano et al. [J. Mech. Phys. Solids 60, 973 (2012), 10.1016/j.jmps.2012.01.006]. Results mark the importance of accounting for viscoelastic effects to correctly simulate the sliding rough contact. In detail, attention is, first, paid to evaluate the viscoelastic dissipation, i.e., the viscoelastic friction. Fixed the sliding speed and the normal load, friction is completely determined. Furthermore, since the methodology employed in the work allows to study contact between real materials, a comparison between experimental outcomes and numerical prediction in terms of viscoelastic friction is shown. The good agreement seems to validate—at least partially—the presented methodology. Finally, it is shown that viscoelasticity entails not only the dissipative effects previously outlined, but is also strictly related to the anisotropy of the contact solution. Indeed, a marked anisotropy is present in the contact region, which results stretched in the direction perpendicular to the sliding speed. In the paper, the anisotropy of the deformed surface and of the contact area is investigated and quantified.

  15. Dual contact pogo pin assembly

    DOEpatents

    Hatch, Stephen McGarry

    2016-06-21

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  16. Dual contact pogo pin assembly

    DOEpatents

    Hatch, Stephen McGarry

    2015-01-20

    A contact assembly includes a base and a pair of electrical contacts supported by the base. A first end of the first electrical contact corresponds to a first end of the base and is configured to engage a first external conductive circuit element. A first end of the second electrical contact also corresponds to the first end of the base and is configured to engage a second external conductive circuit element. The first contact and the second contact are electrically isolated from one another and configured to compress when engaging an external connector element. The base includes an aperture positioned on a second end of the base outboard of a second end of the first and second electrical contacts. The aperture presents a narrowing shape with a wide mouth distal the electrical contacts and a narrow internal through-hole proximate the electrical contacts.

  17. A Brief Analysis of Abraham Maslow's Original Writing of "Self-Actualizing People: A Study of Psychological Health"

    ERIC Educational Resources Information Center

    Francis, Nedra H.; Kritsonis, William Allan

    2006-01-01

    This article analyzes Abraham Maslow's original writing of "Self-Actualizing People: A Study of Psychological Health." The review of literature in this article reveals that Maslow's hierarchy of needs have had profound effects in the area of psychology. In addition, the authors present information regarding self-actualized people, theorists of…

  18. Inverse heat transfer problem of thermal contact conductance estimation in periodically contacting surfaces

    NASA Astrophysics Data System (ADS)

    Shojaeefard, M. H.; Goudarzi, K.; Mazidi, M. Sh.

    2009-06-01

    The problems involving periodic contacting surfaces have different practical applications. An inverse heat conduction problem for estimating the periodic Thermal Contact Conductance (TCC) between one-dimensional, constant property contacting solids has been investigated with conjugate gradient method (CGM) of function estimation. This method converges very rapidly and is not so sensitive to the measurement errors. The advantage of the present method is that no a priori information is needed on the variation of the unknown quantities, since the solution automatically determines the functional form over the specified domain. A simple, straight forward technique is utilized to solve the direct, sensitivity and adjoint problems, in order to overcome the difficulties associated with numerical methods. Two general classes of results, the results obtained by applying inexact simulated measured data and the results obtained by using data taken from an actual experiment are presented. In addition, extrapolation method is applied to obtain actual results. Generally, the present method effectively improves the exact TCC when exact and inexact simulated measurements input to the analysis. Furthermore, the results obtained with CGM and the extrapolation results are in agreement and the little deviations can be negligible.

  19. Contact pressure prediction in total knee joint replacements. Part 1: General elasticity solution for elliptical layered contacts.

    PubMed

    Jin, Z M; Dowson, D; Fisher, J

    1995-01-01

    A general elasticity contact theory has been developed to predict the contact area and the contact pressure in total knee joint replacements with elliptical contacts where the thickness of ultra high molecular weight polyethylene (UHMWPE) is similar or less than the contact half width. The interfacial boundary condition between the UHMWPE component and the underlying metal substrate has been considered to be either perfectly bonded or perfectly unbonded in the model. Poisson's ratio for UHMWPE has been assumed to be 0.3 or 0.4. The effect of the thickness of the UHMWPE layer on the contact area and the contact pressure has been examined. The predictions of the maximum contact pressure and the contact area have been presented in non-dimensional forms and can readily be applied for typical design configurations of current total knee joint replacements. Furthermore, the present results can readily be applied to design considerations for total knee joint replacements to reduce contact stresses within the UHMWPE component. PMID:7669116

  20. Measuring the specific contact resistance of contacts to semiconductor nanowires

    NASA Astrophysics Data System (ADS)

    Mohney, S. E.; Wang, Y.; Cabassi, M. A.; Lew, K. K.; Dey, S.; Redwing, J. M.; Mayer, T. S.

    2005-02-01

    Ohmic contacts to semiconductor nanowires are essential components of many new nanoscale electronic devices. Equations for extracting specific contact resistance (or contact resistivity) from several different test structures have been developed by modeling the metal/semiconductor contact as a transmission line, leading to the development of equations analogous to those used for planar contacts. The advantages and disadvantages of various test structures are discussed. To fabricate test structures using a convenient four-point approach, silicon nanowires have been aligned using field-assisted assembly and contacts fabricated. Finally, specific contact resistances near 5 × 10 -4 Ω cm 2 have been measured for Ti/Au contacts to p-type Si nanowires with diameters of 78 and 104 nm.

  1. Contact resistivities of metal-insulator-semiconductor contacts and metal-semiconductor contacts

    NASA Astrophysics Data System (ADS)

    Yu, Hao; Schaekers, Marc; Barla, Kathy; Horiguchi, Naoto; Collaert, Nadine; Thean, Aaron Voon-Yew; De Meyer, Kristin

    2016-04-01

    Applying simulations and experiments, this paper systematically compares contact resistivities (ρc) of metal-insulator-semiconductor (MIS) contacts and metal-semiconductor (MS) contacts with various semiconductor doping concentrations (Nd). Compared with the MS contacts, the MIS contacts with the low Schottky barrier height are more beneficial for ρc on semiconductors with low Nd, but this benefit diminishes gradually when Nd increases. With high Nd, we find that even an "ideal" MIS contact with optimized parameters cannot outperform the MS contact. As a result, the MIS contacts mainly apply to devices that use relatively low doped semiconductors, while we need to focus on the MS contacts to meet the sub-1 × 10-8 Ω cm2 ρc requirement for future Complementary Metal-Oxide-Semiconductor (CMOS) technology.

  2. Contact dermatitis in hairdressers.

    PubMed

    Nethercott, J R; MacPherson, M; Choi, B C; Nixon, P

    1986-02-01

    18 cases of hand dermatitis in hairdressers seen over a 5-year period are reviewed. The diagnoses in these patients are discussed with reference to other studies of hand dermatitis in hairdressers. Contact allergy due to paraphenylenediamine and related hair dyes was the presenting complaint in younger hairdressers, while formaldehyde allergy occurred in those who were older. The prognosis in the former group of workers with respect to continued employment in the trade tended to be poorer than the latter. Follow-up revealed that hand dermatitis often resulted in the worker not continuing to work in the hairdressing trade. PMID:2940055

  3. Contact dermatitis to methylisothiazolinone*

    PubMed Central

    Scherrer, Maria Antonieta Rios; Rocha, Vanessa Barreto; Andrade, Ana Regina Coelho

    2015-01-01

    Methylisothiazolinone (MI) is a preservative found in cosmetic and industrial products. Contact dermatitis caused by either methylchloroisothiazolinone/methylisothiazolinone (MCI/MI or Kathon CG) or MI has shown increasing frequency. The latter is preferably detected through epicutaneous testing with aqueous MI 2000 ppm, which is not included in the Brazilian standard tray. We describe a series of 23 patients tested using it and our standard tray. A case with negative reaction to MCI/MI and positive to MI is emphasized. PMID:26734880

  4. Allergic Contact Dermatitis

    PubMed Central

    Nelson, Jenny L.

    2010-01-01

    Epicutaneous patch testing is the gold standard method for the diagnosis of allergic contact dermatitis. Despite this knowledge, many clinical dermatologists do not offer patch testing in their offices or offer testing with only a limited number of allergens. Introduced in 1995, the Thin-Layer Rapid Use Epicutaneous Test originally contained 23 allergens and one control. In 2007, five additional allergens were added. This United States Food and Drug Administration-approved patch testing system made patch testing more convenient, and after its introduction, more dermatologists offered patch testing services. However, the number of allergens in the Thin-Layer Rapid Use Epicutaneous Test remains relatively low. Every two years, the North American Contact Dermatitis Group collects and reports the data from patch testing among its members to a standardized series of allergens. In 2005-2006, the Group used a series of 65 allergens. Of the top 30 allergens reported in 2005-2006, 10 were not included in the Thin-Layer Rapid Use Epicutaneous Test. Knowledge of and testing for additional allergens such as these may increase patch testing yield. PMID:20967194

  5. [Systemic contact dermatitis].

    PubMed

    Nowak, Daria; Gomułka, Krzysztof; Dziemieszonek, Paulina; Panaszek, Bernard

    2016-01-01

    Systemic contact dermatitis (SCD) is a skin inflammation occurring in a patient after systemic administration of a hapten, which previously caused an allergic contact skin reaction in the same person. Most frequently, hypersensitivity reactions typical for SCD occur after absorption of haptens with food or inhalation. Haptens occur mainly in the forms of metals and compounds present in natural resins, preservatives, food thickeners, flavorings and medicines. For many years, several studies have been conducted on understanding the pathogenesis of SCD in which both delayed type hypersensitivity (type IV) and immediate type I are observed. Components of the complement system are also suspected to attend there. Helper T cells (Th) (Th1 and Th2), cytotoxic T lymphocytes (Tc), and NK cells play a crucial role in the pathogenesis of SCD. They secrete a number of pro-inflammatory cytokines. In addition, regulatory T cells (Tregs) have an important role. They control and inhibit activity of the immune system during inflammation. Tregs release suppressor cytokines and interact directly with a target cell through presentation of immunosuppressive particles at the cell surface. Diagnostic methods are generally the patch test, oral provocation test, elimination diet and lymphocyte stimulation test. There are many kinds of inflammatory skin reactions caused by systemic haptens' distribution. They are manifested in a variety of clinical phenotypes of the disease. PMID:26943310

  6. Theoretical study on the thermal contact resistance of a space-use deep groove ball bearing

    NASA Astrophysics Data System (ADS)

    Nakajima, Katsuhiko

    The thermal contact resistance between the balls and the inner and outer rings of a space-use deep groove ball bearing is analyzed assuming that heat transfer between smooth contacting elements occurs through the elastic contact areas. It is also assumed that the stationary bearing sustains axial and/or radial loads under steady-state temperature condition. The shapes and sizes of the contact areas are calculated using the Hertzian theory. The thermal analysis is based on an isolated isothermal elliptic contact area supplying heat to an insulated half-space. The formulation of the resistance is given as a function of a geometric factor of the contact area and the thermal conductivity of the bearing. In particular, an expression for the axial load is derived with careful consideration of changes in contact angle induced by elastic deformation at the contact area.

  7. Area law for gapless states from local entanglement thermodynamics

    NASA Astrophysics Data System (ADS)

    Swingle, Brian; McGreevy, John

    2016-05-01

    We demonstrate an area law bound on the ground state entanglement entropy of a wide class of gapless quantum states of matter using a strategy called local entanglement thermodynamics. The bound depends only on thermodynamic data, actually a single exponent, the hyperscaling violation exponent θ . All systems in d spatial dimensions obeying our scaling assumptions and with θ area law, while systems with θ =d -1 can violate the area law at most logarithmically. We also discuss the case of frustration-free Hamiltonians and show that to violate the area law more than logarithmically these systems must have an unusually large number of low energy states. Finally, we make contact with the recently proposed s -source framework and argue that θ and s are related by s =2θ .

  8. Contact heat transfer and thermal contact conductance between nonconforming surfaces in an abrupt contact

    SciTech Connect

    Kumar, R.K.; Kroeger, V.D.

    1996-08-01

    An understanding of the thermal contact conductance behavior when a fuel pin contacts the pressure tube is important in the safety analyses of CANDU reactors. Experiments were therefore performed in a small-scale apparatus with fuel element and pressure tube specimens coming into contact in an argon/oxygen atmosphere, which kinetically simulated steam. The contact was initiated when the fuel-element and pressure-tube specimens were at {approximately} 1,000 C and {approximately} 400 C respectively. The experiments were analyzed using a finite-element code. Heat transfer rates through the contact and thermal contact conductances were determined for contact loads ranging from 20 to 80 N. For most contact loads, the contact conductance increased with time during the transient heat-up of the fuel element specimen. It was found that the calculated thermal contact conductances were in the range of 1 to 30 kW/(m{sup 2} K) based on a reference contact width of 2.5 mm. The variation of contact conductance with contact load was nearly linear.

  9. Contact and non-contact ultrasonic measurement in the food industry: a review

    NASA Astrophysics Data System (ADS)

    Taufiq Mohd Khairi, Mohd; Ibrahim, Sallehuddin; Yunus, Mohd Amri Md; Faramarzi, Mahdi

    2016-01-01

    The monitoring of the food manufacturing process is vital since it determines the safety and quality level of foods which directly affect the consumers’ health. Companies which produce high quality products will gain trust from consumers. This factor helps the companies to make profits. The use of efficient and appropriate sensors for the monitoring process can also reduce cost. The food assessing process based on an ultrasonic sensor has attracted the attention of the food industry due to its excellent capabilities in several applications. The utilization of low or high frequencies for the ultrasonic transducer has provided an enormous benefit for analysing, modifying and guaranteeing the quality of food. The contact and non-contact ultrasonic modes for measurement also contributed significantly to the food processing. This paper presents a review of the application of the contact and non-contact mode of ultrasonic measurement focusing on safety and quality control areas. The results from previous researches are shown and elaborated.

  10. Contact Binary Asteroids

    NASA Astrophysics Data System (ADS)

    Rieger, Samantha

    2015-05-01

    Recent observations have found that some contact binaries are oriented such that the secondary impacts with the primary at a high inclination. This research investigates the evolution of how such contact binaries came to exist. This process begins with an asteroid pair, where the secondary lies on the Laplace plane. The Laplace plane is a plane normal to the axis about which the pole of a satellites orbit precesses, causing a near constant inclination for such an orbit. For the study of the classical Laplace plane, the secondary asteroid is in circular orbit around an oblate primary with axial tilt. This system is also orbiting the Sun. Thus, there are two perturbations on the secondarys orbit: J2 and third body Sun perturbations. The Laplace surface is defined as the group of orbits that lie on the Laplace plane at varying distances from the primary. If the secondary is very close to the primary, the inclination of the Laplace plane will be near the equator of the asteroid, while further from the primary the inclination will be similar to the asteroid-Sun plane. The secondary will lie on the Laplace plane because near the asteroid the Laplace plane is stable to large deviations in motion, causing the asteroid to come to rest in this orbit. Assuming the secondary is asymmetrical in shape and the bodys rotation is synchronous with its orbit, the secondary will experience the BYORP effect. BYORP can cause secular motion such as the semi-major axis of the secondary expanding or contracting. Assuming the secondary expands due to BYORP, the secondary will eventually reach the unstable region of the Laplace plane. The unstable region exists if the primary has an obliquity of 68.875 degrees or greater. The unstable region exists at 0.9 Laplace radius to 1.25 Laplace radius, where the Laplace radius is defined as the distance from the central body where the inclination of the Laplace plane orbit is half the obliquity. In the unstable region, the eccentricity of the orbit

  11. Gas fireplace contact burns in young children.

    PubMed

    Zettel, Julie C; Khambalia, Amina; Barden, Wendy; Murthy, Trisha; Macarthur, Colin

    2004-01-01

    Contact burns from domestic appliances are common in young children. Recently, gas fireplaces have been recognized as a potential cause of contact burns in young children. We sought to quantify the frequency of gas fireplace contact burns in young children, to identify the etiology of contact, to describe the clinical presentation, and to describe clinical outcomes. Children with gas fireplace contact burn injuries presenting to The Hospital for Sick Children in Toronto (1999-2002) were identified using three data sources: the Canadian Hospitals Injury Reporting and Prevention Program Database, the Burn Unit Registry, and the Rehabilitation Services Database. Demographic, clinical, and outcomes data were collected on all children. During the 4-year study period, 27 children presented to the hospital because of a gas fireplace contact burn (approximately 9% of all contact burns). The median age of the children was 14 months (range, 8-36 months), with 16 boys (59%). Most children were burned in their own home. With regard to etiology, 10 children (37%) lost their balance near the fireplace, 2 (7%) walked too close to the glass front, and 8 (30%) touched the glass front out of curiosity. Almost half (44%) of the children burned the palms and digits of both hands. The median total burn surface area was 1% (range, 0.2-2.5%). In total, 30% of children were admitted to hospital, and 11% required skin grafts. All children had full wound closure after 4 to 43 days. Given the etiology of these burns (loss of balance or curiosity), passive prevention, such as barriers or changes in the composition of glass panels, may be the most effective approach to combat them. PMID:15534461

  12. 36 CFR 1239.12 - Whom may agencies contact to request program assistance?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Whom may agencies contact to... § 1239.12 Whom may agencies contact to request program assistance? Agencies in the Washington, DC, area desiring information or assistance related to any of the areas covered by subchapter B may contact...

  13. 36 CFR 1239.12 - Whom may agencies contact to request program assistance?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 3 2011-07-01 2011-07-01 false Whom may agencies contact to... § 1239.12 Whom may agencies contact to request program assistance? Agencies in the Washington, DC, area desiring information or assistance related to any of the areas covered by subchapter B may contact...

  14. Can One Measure a Sprachbund? A Calculus of Phonemic Distribution for Language Contact.

    ERIC Educational Resources Information Center

    Afendras, Evangelos A.

    Language contact and the resulting interference has long been diagnosed as one of the primary forces behind language change. In cases of multilingual contact within geographically restricted areas, converging changes of the languages in contact have been uncovered and described. The geographic areas characterized by such linguistic situations came…

  15. Estimation of Regional-Scale Actual Evapotranspiration in Okayama prefecture in Japan using Complementary Relationship

    NASA Astrophysics Data System (ADS)

    Moroizumi, T.; Yamamoto, M.; Miura, T.

    2008-12-01

    It is important to estimate accurately a water balance in watershed for proposing a reuse of water resources and a proper settlement of water utilization. Evapotranspiration (ET) is an important factor of water balance. Therefore, it is needed to estimate accurately the actual ET. The objective of this study is to estimate accurately monthly actual ET in Yoshii, Asahi, and Takahashi River watersheds in Okayama prefecture from 1999 to 2000. The monthly actual ET was calculated by a Morton and a modified Brutsaert and Stricker (B&S) method, using Automated Meteorological Data Acquisition Systems (AMeDAS) in the basin. The actual ET was estimated using land covers which were classified in 11 categories. The land covers includes the effects of albedo. The actual ET was related to the elevation at each AMeDAS station. Using this relationship, the actual ET at the 1 or 5 km grid-interval mesh in the basin was calculated, and finally, the distribution of actual ET was mapped. The monthly ET estimated by the modified B&S method were smaller than that by Morton method which showed a same tendency as the Penman potential ET (PET). The annual values of Morton"fs ET, modified B&S"fs ET, and PET were estimated as 796, 645, and 800 mm, respectively. The ET by the modified B&S was larger in hilly and mountainous areas than in settlement or city. In general, it was a reasonable result because city or settlement areas were covered with concrete and asphalt and the ET was controlled.

  16. Occupational contact dermatitis in the pharmaceutical industry.

    PubMed

    Goossens, An; Hulst, Kim Vander

    2011-01-01

    Occupation-induced skin reactions are not infrequently observed in the pharmaceutical industry. Workers may come in contact with irritant substances and also with chemically reactive intermediates or drugs that may be potential sensitizers. The skin lesions can be located at the site of contact, usually the hands, although airborne reactions on exposed and even nonexposed areas (eg, by particles trapped under clothing) are not uncommon. Generalized reactions may occur due to inhalation or transcutaneous absorption. An accidental exposure to a highly allergenic compound may cause a chemical burn, followed by primary sensitization and allergic contact dermatitis. The pharmaceutical contact allergens belong to many different pharmacologic classes. If several cases of contact dermatitis occur in multiple individuals in the same company, then the working conditions are implicated and should be changed to prevent their recurrence. Measures to be taken include dust control, installation of closed filter equipment, and keeping the workers informed about the potential risks associated with the manipulation of the chemicals. PMID:22014988

  17. Contact urticaria from rice.

    PubMed

    Yamakawa, Y; Ohsuna, H; Aihara, M; Tsubaki, K; Ikezawa, Z

    2001-02-01

    A 30-year-old man with atopic dermatitis had had erythema and itching of the hands after washing rice in water, though he had always eaten cooked rice without problems. Handling test with water used to wash regular rice was performed on abraded hands, and produced urticarial erythema after several minutes. Applications of water used to wash allergen-reduced rice were negative for urticarial reaction. Prick test with water used to wash regular rice was +++. However prick test reaction with water used to wash allergen-reduced rice was +. Histamine-release test of regular rice-washing water was grade 3 and that of allergen-reduced rice grade 1. In immunoblotting analysis with regular rice washing water, there were no bands with this patient. These results suggest that the allergen responsible for contact urticaria in this patient might be water-soluble, heat-unstable, and not contained in allergen-reduced rice. PMID:11205411

  18. Contact dermatitis to Alstroemeria.

    PubMed

    Santucci, B; Picardo, M; Iavarone, C; Trogolo, C

    1985-04-01

    A study was carried out on 50 workers in a floriculture centre to evaluate the incidence of contact dermatitis to Alstroemeria. 3 subjects gave positive reactions to aqueous and ethanolic extracts of cut flowers, stems and leaves. By column chromatography, the allergen was isolated and its chemical structure identified as 6-tuliposide A by proton magnetic resonance and carbon-13 magnetic resonance. Only 6-tuliposide A was isolated from cut flowers, and this gave positive reactions when patch tested at 0.01%; a-methylene-gamma-butyrolactone at 10(-5) (v/v) was positive in the same 3 subjects. Other lactones (gamma-methylene-gamma-butyrolactone, alantolactone, isoalantolactone) were negative at all concentrations used. PMID:3160533

  19. Contact dermatitis in blacks.

    PubMed

    Berardesca, E; Maibach, H I

    1988-07-01

    Black skin is characterized by structural and functional differences such as increased stratum corneum cohesion, melanin content, and stratum corneum layers. These differences seem to make black skin difficult for irritants and light to penetrate, thus explaining the common opinion that skin in blacks is harder and develops contact dermatitis less frequently. The paucity of interpretable epidemiologic data and of clinical and experimental studies does not permit confirmation of this hypothesis, and the few data available are controversial. This article describes the main physiologic differences between black and white barrier function and reviews the literature on irritation, sensitization, and transcutaneous penetration. We found that the data are still too incomplete to generalize on the resistance, or lack thereof, of black skin (versus white skin) to chemical irritation, sensitization, and penetration. PMID:3048818

  20. Investigation of different contact geometries for partial rear metal contact of high-efficiency silicon solar cells

    NASA Astrophysics Data System (ADS)

    Mitra, Suchismita; Ghosh, Hemanta; Saha, Hiranmay; Datta, Swapan Kumar

    2015-11-01

    In this paper, we have investigated the dependence of the parameters of partial rear metal contact (PRC) solar cells on two commonly used geometrical configurations, viz. grid contact and square contact. It is demonstrated that while the geometry of rear metallic contact having the same fractional coverage changes the base spreading resistance significantly, rear surface passivation and back reflectance depend only on the fractional coverage of the real metal contact and are independent of the geometry of the contact. The performed analysis indicates that the base spreading resistance is much higher for square contact cells compared to that of grid contact cells having the same fractional coverage. While open-circuit voltage and short-circuit current are found to be essentially independent of the contact geometry, the fill factor is significantly affected by the geometry, indicating that the design of high-efficiency cells with partial rear grid contact is less critical in comparison to that of square contact cells for optimized performance. Results indicate that for a 180 μm cell, an efficiency enhancement of 14% is possible for  <10% fractional rear metallization over the baseline efficiency of about 19% for solar cells having full-area rear metallization. For 50 μm thin cells, the corresponding improvement in efficiency is 17%, leading to 22% efficiency solar cells.

  1. Point contacts in encapsulated graphene

    SciTech Connect

    Handschin, Clevin; Fülöp, Bálint; Csonka, Szabolcs; Makk, Péter; Blanter, Sofya; Weiss, Markus; Schönenberger, Christian; Watanabe, Kenji; Taniguchi, Takashi

    2015-11-02

    We present a method to establish inner point contacts with dimensions as small as 100 nm on hexagonal boron nitride (hBN) encapsulated graphene heterostructures by pre-patterning the top-hBN in a separate step prior to dry-stacking. 2- and 4-terminal field effect measurements between different lead combinations are in qualitative agreement with an electrostatic model assuming point-like contacts. The measured contact resistances are 0.5–1.5 kΩ per contact, which is quite low for such small contacts. By applying a perpendicular magnetic field, an insulating behaviour in the quantum Hall regime was observed, as expected for inner contacts. The fabricated contacts are compatible with high mobility graphene structures and open up the field for the realization of several electron optical proposals.

  2. A Prototype Antifungal Contact Lens

    PubMed Central

    Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.

    2011-01-01

    Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380

  3. Transient analysis of thermoelastic contact problem of disk brakes

    NASA Astrophysics Data System (ADS)

    Belhocine, Ali; Bouchetara, Mostefa

    2013-06-01

    The main purpose of this study is to analyze the thermomechanical behavior of the dry contact between the brake disk and pads during the braking phase. The simulation strategy is based on computer code ANSYS11. The modeling of transient temperature in the disk is actually used to identify the factor of geometric design of the disk to install the ventilation system in vehicles. The thermal-structural analysis is then used with coupling to determine the deformation established and the Von Mises stresses in the disk, the contact pressure distribution in pads. The results are satisfactory compared to those found in the literature.

  4. Relaxation of contact-line singularities solely by the Kelvin effect and apparent contact angles for isothermal volatile liquids in contact with air

    NASA Astrophysics Data System (ADS)

    Rednikov, Alexey; Colinet, Pierre

    2013-11-01

    The contact (triple) line of a volatile liquid on a flat solid is studied theoretically. Like with a pure-vapor atmosphere [Phys. Rev. E 87, 010401, 2013], but here for isothermal diffusion-limited evaporation/condensation in the presence of an inert gas, we rigorously show that the notorious contact-line singularities (related to motion or phase change itself) can be regularized solely on account of the Kelvin effect (curvature dependence of the saturation conditions). No disjoining pressure, precursor films or Navier slip are in fact needed to this purpose, and nor are they taken into consideration here (``minimalist'' approach). The model applies to both perfect (zero Young's angle) and partial wetting, and is in particular used to study the related issue of evaporation-induced contact angles. Their modification by the contact-line motion (either advancing or receding) is assessed. The formulation is posed for a distinguished immediate vicinity of the contact line (the ``microregion''), the corresponding problem decoupling to leading order, here up to one unknown coefficient, from what actually happens at the macroscale. The lubrication approximation (implying sufficiently small contact angles) is used in the liquid, coupled with the diffusion equation in the gaz phase. Supported by ESA and BELSPO PRODEX and F.R.S.-FNRS.

  5. Analysis of metal-metal contacts in RF MEMS switches

    NASA Astrophysics Data System (ADS)

    Kurth, Steffen; Voigt, Sven; Haas, Sven; Bertz, Andreas; Kaufmann, Christian; Gessner, Thomas; Akiba, Akira; Ikeda, Koichi

    2013-03-01

    This contribution reports on the analysis of metal-metal contacts of MEMS switches. A novel high aspect ratio MEMS fabrication sequence in combination with wafer level packaging is applied for fabrication of an RF MEMS switch with lateral motion. It allows for a relatively large actuation electrode area in a small package, and for high actuation force even with an actuation voltage of 5 V. The focus of this contribution is on the contact behavior. It is shown how operation conditions as like as actuation voltage, RF power, and DC bias influence the contact resistance. The power handling capability and its influence on the contacts, and the intermodulation were investigated also.

  6. Alternate corrections for estimating actual wetland evapotranspiration from potential evapotranspiration

    USGS Publications Warehouse

    Barclay, Shoemaker W.; Sumner, D.M.

    2006-01-01

    Corrections can be used to estimate actual wetland evapotranspiration (AET) from potential evapotranspiration (PET) as a means to define the hydrology of wetland areas. Many alternate parameterizations for correction coefficients for three PET equations are presented, covering a wide range of possible data-availability scenarios. At nine sites in the wetland Everglades of south Florida, USA, the relatively complex PET Penman equation was corrected to daily total AET with smaller standard errors than the PET simple and Priestley-Taylor equations. The simpler equations, however, required less data (and thus less funding for instrumentation), with the possibility of being corrected to AET with slightly larger, comparable, or even smaller standard errors. Air temperature generally corrected PET simple most effectively to wetland AET, while wetland stage and humidity generally corrected PET Priestley-Taylor and Penman most effectively to wetland AET. Stage was identified for PET Priestley-Taylor and Penman as the data type with the most correction ability at sites that are dry part of each year or dry part of some years. Finally, although surface water generally was readily available at each monitoring site, AET was not occurring at potential rates, as conceptually expected under well-watered conditions. Apparently, factors other than water availability, such as atmospheric and stomata resistances to vapor transport, also were limiting the PET rate. ?? 2006, The Society of Wetland Scientists.

  7. Wireless Measurement of Contact and Motion Between Contact Surfaces

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.

    2007-01-01

    This method uses a magnetic-field- response contact sensor that is designed to identify surface contact and motion between contact locations. The sensor has three components: (1) a capacitor-inductor circuit with two sets of electrical contact pads, (2) a capacitor with a set of electrical contact pads, and (3) an inductor with a set of electrical contact pads. A unique feature of this sensor is that it is inherently multifunctional. Information can be derived from analyzing such sensor response attributes as amplitude, frequency, and bandwidth. A change in one attribute can be due to a change in a physical property of a system. A change in another attribute can be due to another physical property, which has no relationship to the first one.

  8. Establishing seasonal chronicles of actual evapotranspiration under sloping conditions

    NASA Astrophysics Data System (ADS)

    Zitouna Chebbi, R.; Prévot, L.; Jacob, F.; Voltz, M.

    2012-04-01

    Estimation of daily and seasonal actual evapotranspiration (ETa) is strongly needed for hydrological and agricultural purposes. Although the eddy covariance method is well suited for such estimation of land surface fluxes, this method suffers from limitations when establishing long time series. Missing data are often encountered, resulting from bad meteorological conditions, rejection by quality control tests, power failures… Numerous gap fill techniques have been proposed in the literature but there applicability in sloping conditions is not well known. In order to estimate ETa over long periods (agricultural cycle) on crops cultivated in sloping areas, a pluri-annual experiment was conducted in the Kamech catchment, located in North-eastern Tunisia. This Mediterranean site is characterized by a large heterogeneity in topography, soils and crops. Land surface fluxes were measured using eddy covariance systems. Measurements were collected on the two opposite sides of the Kamech V-shaped catchment, within small fields having slopes steeper than 5%. During three different years, four crops were studied: durum wheat, oat, fava bean and pasture. The topography of the catchment and the wind regime induced upslope and downslope flows over the study fields. In this study, we showed that gap filling of the turbulent fluxes (sensible and latent heat) can be obtained through linear regressions against net radiation. To account for the effect of the topography, linear regressions were calibrated by distinguishing upslope and downslope flows. This significantly improved the quality of the reconstructed data over 30 minute intervals. This gap filling technique also improved the energy balance closure at the daily time scale. As a result, seasonal chronicles of daily ETa throughout the growth cycle of the study crops in the Kamech watershed were established, thus providing useful information about the water use of annual crops in a semi-arid rainfed and hilly area.

  9. JKR adhesion in cylindrical contacts

    NASA Astrophysics Data System (ADS)

    Sundaram, Narayan; Farris, T. N.; Chandrasekar, S.

    2012-01-01

    Planar JKR adhesive solutions use the half-plane assumption and do not permit calculation of indenter approach or visualization of adhesive force-displacement curves unless the contact is periodic. By considering a conforming cylindrical contact and using an arc crack analogy, we obtain closed-form indenter approach and load-contact size relations for a planar adhesive problem. The contact pressure distribution is also obtained in closed-form. The solutions reduce to known cases in both the adhesion-free and small-contact solution ( Barquins, 1988) limits. The cylindrical system shows two distinct regimes of adhesive behavior; in particular, contact sizes exceeding the critical (maximum) size seen in adhesionless contacts are possible. The effects of contact confinement on adhesive behavior are investigated. Some special cases are considered, including contact with an initial neat-fit and the detachment of a rubbery cylinder from a rigid cradle. A comparison of the cylindrical solution with the half-plane adhesive solution is carried out, and it indicates that the latter typically underestimates the adherence force. The cylindrical adhesive system is novel in that it possesses stable contact states that may not be attained even on applying an infinite load in the absence of adhesion.

  10. Hysteresis during contact angles measurement.

    PubMed

    Diaz, M Elena; Fuentes, Javier; Cerro, Ramon L; Savage, Michael D

    2010-03-15

    A theory, based on the presence of an adsorbed film in the vicinity of the triple contact line, provides a molecular interpretation of intrinsic hysteresis during the measurement of static contact angles. Static contact angles are measured by placing a sessile drop on top of a flat solid surface. If the solid surface has not been previously in contact with a vapor phase saturated with the molecules of the liquid phase, the solid surface is free of adsorbed liquid molecules. In the absence of an adsorbed film, molecular forces configure an advancing contact angle larger than the static contact angle. After some time, due to an evaporation/adsorption process, the interface of the drop coexists with an adsorbed film of liquid molecules as part of the equilibrium configuration, denoted as the static contact angle. This equilibrium configuration is metastable because the droplet has a larger vapor pressure than the surrounding flat film. As the drop evaporates, the vapor/liquid interface contracts and the apparent contact line moves towards the center of the drop. During this process, the film left behind is thicker than the adsorbed film and molecular attraction results in a receding contact angle, smaller than the equilibrium contact angle. PMID:20060981

  11. 26 CFR 1.953-2 - Actual United States risks.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ..., and water damage risks incurred when property is actually located in the United States and marine... 26 Internal Revenue 10 2014-04-01 2013-04-01 true Actual United States risks. 1.953-2 Section 1... coverage as “.825% plus .3% fire, etc. risks plus .12% water risks = 1.245%”, a reasonable basis exists...

  12. Self-actualization: Its Use and Misuse in Teacher Education.

    ERIC Educational Resources Information Center

    Ivie, Stanley D.

    1982-01-01

    The writings of Abraham Maslow are analyzed to determine the meaning of the psychological term "self-actualization." After pointing out that self-actualization is a rare quality and that it has little to do with formal education, the author concludes that the concept has little practical relevance for teacher education. (PP)

  13. The Self-Actualization of Polk Community College Students.

    ERIC Educational Resources Information Center

    Pearsall, Howard E.; Thompson, Paul V., Jr.

    This article investigates the concept of self-actualization introduced by Abraham Maslow (1954). A summary of Maslow's Needs Hierarchy, along with a description of the characteristics of the self-actualized person, is presented. An analysis of humanistic education reveals it has much to offer as a means of promoting the principles of…

  14. From Self-Awareness to Self-Actualization

    ERIC Educational Resources Information Center

    Cangemi, Joseph P.; Englander, Meryl R.

    1974-01-01

    Highest priority of education is to help students utilize as much of their talent as is possible. Third Force psychologists would interpret this as becoming self-actualized. Self-awareness is required for psychological growth. Without self-awareness there can be no growth, no mental hygiene, and no self-actualization. (Author)

  15. 12 CFR 1806.203 - Selection Process, actual award amounts.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Selection Process, actual award amounts. 1806... OF THE TREASURY BANK ENTERPRISE AWARD PROGRAM Awards § 1806.203 Selection Process, actual award... round: (1) To select Applicants not previously selected, using the calculation and selection...

  16. Self-Actualization and the Effective Social Studies Teacher.

    ERIC Educational Resources Information Center

    Farmer, Rodney B.

    1980-01-01

    Discusses a study undertaken to investigate the relationship between social studies teachers' degrees of self-actualization and their teacher effectiveness. Investigates validity of using Maslow's theory of self-actualization as a way of identifying the effective social studies teacher personality. (Author/DB)

  17. Facebook as a Library Tool: Perceived vs. Actual Use

    ERIC Educational Resources Information Center

    Jacobson, Terra B.

    2011-01-01

    As Facebook has come to dominate the social networking site arena, more libraries have created their own library pages on Facebook to create library awareness and to function as a marketing tool. This paper examines reported versus actual use of Facebook in libraries to identify discrepancies between intended goals and actual use. The results of a…

  18. Perceived and Actual Student Support Needs in Distance Education.

    ERIC Educational Resources Information Center

    Visser, Lya; Visser, Yusra Laila

    2000-01-01

    This study sought to determine the academic, affective, and administrative support expectations of distance education students, and to compare actual expectations of distance education students with the instructor's perceptions of such expectations. Results demonstrated divergence between perceived and actual expectations of student support in…

  19. Gebrauchstexte im Fremdsprachenunterricht ("Actual" Texts in Foreign Language Teaching)

    ERIC Educational Resources Information Center

    Ziegesar, Detlef von

    1976-01-01

    Presents for analysis actual texts and texts specially written for teaching, arriving at a basis for a typology of actual texts. Defines teaching aims using such texts, and develops, from a TV program, a teaching unit used in a Karlsruhe school. (Text is in German.) (IFS/WGA)

  20. Self-Actualizing Men and Women: A Comparison Study.

    ERIC Educational Resources Information Center

    Hall, Eleanor G.; Hansen, Jan B.

    1997-01-01

    The self-actualization of 167 women who lived in the Martha Cook (MC) dormitory of the University of Michigan (1950-1970) was compared to that of a group of Ivy League men researched in another study. In addition, two groups of MC women were compared to each other to identify differences which might explain why some self-actualized while other did…

  1. SELF-ACTUALIZATION AND THE UTILIZATION OF TALENT.

    ERIC Educational Resources Information Center

    FRENCH, JOHN R.P.; MILLER, DANIEL R.

    THIS STUDY ATTEMPTED (1) TO DEVELOP A THEORY OF THE CAUSES AND CONSEQUENCES OF SELF-ACTUALIZATION AS RELATED TO THE UTILIZATION OF TALENT, (2) TO FIT THE THEORY TO EXISTING DATA, AND (3) TO PLAN ONE OR MORE RESEARCH PROJECTS TO TEST THE THEORY. TWO ARTICLES ON IDENTITY AND MOTIVATION AND SELF-ACTUALIZATION AND SELF-IDENTITY THEORY REPORTED THE…

  2. Self-Actualization Effects Of A Marathon Growth Group

    ERIC Educational Resources Information Center

    Jones, Dorothy S.; Medvene, Arnold M.

    1975-01-01

    This study examined the effects of a marathon group experience on university student's level of self-actualization two days and six weeks after the experience. Gains in self-actualization as a result of marathon group participation depended upon an individual's level of ego strength upon entering the group. (Author)

  3. 26 CFR 1.962-3 - Treatment of actual distributions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 26 Internal Revenue 10 2013-04-01 2013-04-01 false Treatment of actual distributions. 1.962-3... TAX (CONTINUED) INCOME TAXES (CONTINUED) Controlled Foreign Corporations § 1.962-3 Treatment of actual... a foreign corporation. (ii) Treatment of section 962 earnings and profits under § 1.959-3....

  4. School Guidance Counselors' Perceptions of Actual and Preferred Job Duties

    ERIC Educational Resources Information Center

    Edwards, John Dexter

    2010-01-01

    The purpose of this study was to provide process data for school counselors, administrators, and the public, regarding school counselors' actual roles within the guidance counselor preferred job duties and actual job duties. In addition, factors including National Certification or no National Certification, years of counseling experience, and…

  5. Antistiction technique using elastomer contact structure in woven electronic textiles

    NASA Astrophysics Data System (ADS)

    Yamashita, Takahiro; Takamatsu, Seiichi; Miyake, Koji; Itoh, Toshihiro

    2014-01-01

    In this paper, we present an antistiction technique using an elastomer contact structure in woven electronic textiles (e-textiles). A coating of poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate) (PEDOT:PSS) in the form of a solid conductive film on a hemispherical silicone elastomer structure is employed in creating an electrical circuit embedded into the fabric of a woven e-textile, where the contact structure reduces the contact area and capillary force generated by the moisture in air between weft and warp ribbons. Stiction occurs between a weft and a warp without the contact structure under an RH of 80%, and the detachment of the stuck ribbon requires a delamination load of about 0.2 N. On the other hand, in the case of contact between the contact structure and the ribbon coated with plain PEDOT:PSS, stiction does not occur as the relative humidity increases from 20 to 80%.

  6. Contact Patterns in a High School: A Comparison between Data Collected Using Wearable Sensors, Contact Diaries and Friendship Surveys.

    PubMed

    Mastrandrea, Rossana; Fournet, Julie; Barrat, Alain

    2015-01-01

    Given their importance in shaping social networks and determining how information or transmissible diseases propagate in a population, interactions between individuals are the subject of many data collection efforts. To this aim, different methods are commonly used, ranging from diaries and surveys to decentralised infrastructures based on wearable sensors. These methods have each advantages and limitations but are rarely compared in a given setting. Moreover, as surveys targeting friendship relations might suffer less from memory biases than contact diaries, it is interesting to explore how actual contact patterns occurring in day-to-day life compare with friendship relations and with online social links. Here we make progresses in these directions by leveraging data collected in a French high school and concerning (i) face-to-face contacts measured by two concurrent methods, namely wearable sensors and contact diaries, (ii) self-reported friendship surveys, and (iii) online social links. We compare the resulting data sets and find that most short contacts are not reported in diaries while long contacts have a large reporting probability, and that the durations of contacts tend to be overestimated in the diaries. Moreover, measured contacts corresponding to reported friendship can have durations of any length but all long contacts do correspond to a reported friendship. On the contrary, online links that are not also reported in the friendship survey correspond to short face-to-face contacts, highlighting the difference of nature between reported friendships and online links. Diaries and surveys suffer moreover from a low sampling rate, as many students did not fill them, showing that the sensor-based platform had a higher acceptability. We also show that, despite the biases of diaries and surveys, the overall structure of the contact network, as quantified by the mixing patterns between classes, is correctly captured by both networks of self-reported contacts and

  7. Contact Patterns in a High School: A Comparison between Data Collected Using Wearable Sensors, Contact Diaries and Friendship Surveys

    PubMed Central

    Mastrandrea, Rossana; Fournet, Julie; Barrat, Alain

    2015-01-01

    Given their importance in shaping social networks and determining how information or transmissible diseases propagate in a population, interactions between individuals are the subject of many data collection efforts. To this aim, different methods are commonly used, ranging from diaries and surveys to decentralised infrastructures based on wearable sensors. These methods have each advantages and limitations but are rarely compared in a given setting. Moreover, as surveys targeting friendship relations might suffer less from memory biases than contact diaries, it is interesting to explore how actual contact patterns occurring in day-to-day life compare with friendship relations and with online social links. Here we make progresses in these directions by leveraging data collected in a French high school and concerning (i) face-to-face contacts measured by two concurrent methods, namely wearable sensors and contact diaries, (ii) self-reported friendship surveys, and (iii) online social links. We compare the resulting data sets and find that most short contacts are not reported in diaries while long contacts have a large reporting probability, and that the durations of contacts tend to be overestimated in the diaries. Moreover, measured contacts corresponding to reported friendship can have durations of any length but all long contacts do correspond to a reported friendship. On the contrary, online links that are not also reported in the friendship survey correspond to short face-to-face contacts, highlighting the difference of nature between reported friendships and online links. Diaries and surveys suffer moreover from a low sampling rate, as many students did not fill them, showing that the sensor-based platform had a higher acceptability. We also show that, despite the biases of diaries and surveys, the overall structure of the contact network, as quantified by the mixing patterns between classes, is correctly captured by both networks of self-reported contacts and

  8. Surface roughness, asperity contact and gold RF MEMS switch behavior

    NASA Astrophysics Data System (ADS)

    Rezvanian, O.; Zikry, M. A.; Brown, C.; Krim, J.

    2007-10-01

    Modeling predictions and experimental measurements were obtained to characterize the electro-mechanical response of radio frequency (RF) microelectromechanical (MEM) switches due to variations in surface roughness and finite asperity deformations. Three-dimensional surface roughness profiles were generated, based on a Weierstrass-Mandelbrot fractal representation, to match the measured roughness characteristics of contact bumps of manufactured RF MEMS switches. Contact asperity deformations due to applied contact pressures were then obtained by a creep constitutive formulation. The contact pressure is derived from the interrelated effects of roughness characteristics, material hardening and softening, temperature increases due to Joule heating and contact forces. This modeling framework was used to understand how contact resistance evolves due to changes in the real contact area, the number of asperities in contact, and the temperature and resistivity profiles at the contact points. The numerical predictions were qualitatively consistent with the experimental measurements and observations of how contact resistance evolves as a function of deformation time history. This study provides a framework that is based on integrated modeling and experimental measurements, which can be used in the design of reliable RF MEMS devices with extended life cycles.

  9. Contact activation of blood-plasma coagulation

    NASA Astrophysics Data System (ADS)

    Golas, Avantika

    "adsorption-dilution" effect that blocks FXII contact with hydrophobic activator surfaces. The adsorption-dilution effect explains the apparent specificity for hydrophilic activators pursued by earlier investigators. Finally a comparison of FXII autoactivation in buffer, serum, protein cocktail, and plasma solutions is shown herein. Activation of blood plasma coagulation in vitro by contact with material surfaces is demonstrably dependent on plasma-volume-to-activator-surface-area ratio. However, activation of factor XII dissolved in buffer, protein cocktail, heat-denatured serum, and FXI deficient plasma does not exhibit activator surface-area dependence. Instead, a highly-variable burst of procoagulant-enzyme yield is measured that exhibits no measurable kinetics, sensitivity to mixing, or solution-temperature dependence. Thus, FXII activation in both buffer and protein-containing solutions does not exhibit characteristics of a biochemical reaction but rather appears to be a "mechanochemical" reaction induced by FXII molecule interactions with hydrophilic activator particles that do not formally adsorb blood proteins from solution. Results strongly suggest that activator surface-area dependence observed in contact activation of plasma coagulation does not solely arise at the FXII activation step of the intrinsic pathway.

  10. Impact of environmental conditions on the contact physics of gold contact RF microelectromechanical systems (MEMS) switches

    NASA Astrophysics Data System (ADS)

    Brown, Christopher John

    RF MEMS switch technology is poised to create a new generation of devices capable of vastly outperforming current mechanical and semiconductor switching technology. Despite the efforts of top industrial, academic, and government labs, commercialization of RF MEMS switches has lagged expectations. This dissertation focuses on issues associated with switch contact physics. Understanding the failure mechanisms for metal contact switches is a complex challenge. There is strong interplay between variables such as mechanical creep, deformation, contact heating, contact asperity size, real contact area, and current flow leading to the eventual failure of the switch. Stiction failures moreover are highly sensitive to ambient conditions and absorbed film layers at the switch contact. The experiments in this thesis seek to isolate individual failure mechanisms and tie them to the physics driving that behavior through correlation of experimental data and theoretical modeling. Four experiments in controlled environments were performed: (1) the impact of cryogenic temperatures on RF MEMS contacts, (2) a correlation between experimental data and theoretical modeling for gold asperity creep at room and cryogenic temperatures, (3) a power law relationship between contact resistance and time dependent creep, and (4) the pressure dependence of switch closure. Cryogenic temperatures were used to isolate contaminant film effects. Contaminant films were found to have less mobility at 77 K, and contact resistance measurements showed that the film could be reduced on the contact surface through mechanical cycling and high temperatures at the gold asperities. It was also noted at cryogenic temperatures that the choice of atmosphere was important. A nitrogen atmosphere at liquid nitrogen temperature produced variable contact resistance as the condensed liquid boiled off the switch contacts. Data was correlated with a single asperity creep model to show that change in contact resistance as

  11. Wearable telescopic contact lens.

    PubMed

    Arianpour, Ashkan; Schuster, Glenn M; Tremblay, Eric J; Stamenov, Igor; Groisman, Alex; Legerton, Jerry; Meyers, William; Amigo, Goretty Alonso; Ford, Joseph E

    2015-08-20

    We describe the design, fabrication, and testing of a 1.6 mm thick scleral contact lens providing both 1× and 2.8× magnified vision paths, intended for use as a switchable eye-borne telescopic low-vision aid. The F/9.7 telescopic vision path uses an 8.2 mm diameter annular entrance pupil and 4 internal reflections in a polymethyl methacrylate precision optic. This gas-impermeable insert is contained inside a smooth outer casing of rigid gas-permeable polymer, which also provides achromatic correction for refraction at the curved lens face. The unmagnified F/4.1 vision path is through the central aperture of the lens, with additional transmission between the annular telescope rings to enable peripheral vision. We discuss potential solutions for providing oxygenation for an extended wear version of the lens. The prototype lenses were characterized using a scale-model human eye, and telescope functionality was confirmed in a small-scale clinical (nondispensed) demonstration. PMID:26368753

  12. Protein folding using contact maps.

    PubMed

    Vendruscolo, M; Domany, E

    2000-01-01

    We discuss the problem of representations of protein structure and give the definition of contact maps. We present a method to obtain a three-dimensional polypeptide conformation from a contact map. We also explain how to deal with the case of nonphysical contact maps. We describe a stochastic method to perform dynamics in contact map space. We explain how the motion is restricted to physical regions of the space. First, we introduce the exact free energy of a contact map and discuss two simple approximations to it. Second, we present a method to derive energy parameters based on perception learning. We prove in an extensive number of situations that the pairwise contact approximation both when alone and when supplemented with a hydrophobic term is unsuitable for stabilizing proteins' native states. PMID:10668399

  13. Method for forming metal contacts

    SciTech Connect

    Reddington, Erik; Sutter, Thomas C; Bu, Lujia; Cannon, Alexandra; Habas, Susan E; Curtis, Calvin J; Miedaner, Alexander; Ginley, David S; Van Hest, Marinus Franciscus Antonius Maria

    2013-09-17

    Methods of forming metal contacts with metal inks in the manufacture of photovoltaic devices are disclosed. The metal inks are selectively deposited on semiconductor coatings by inkjet and aerosol apparatus. The composite is heated to selective temperatures where the metal inks burn through the coating to form an electrical contact with the semiconductor. Metal layers are then deposited on the electrical contacts by light induced or light assisted plating.

  14. Contact between traps and surfaces during contact sampling of explosives in security settings.

    PubMed

    Chaffee-Cipich, Michelle N; Hoss, Darby J; Sweat, Melissa L; Beaudoin, Stephen P

    2016-03-01

    Realistic descriptions of interfacial contact between rough, deformable surfaces under load are difficult to obtain; however, this contact is of great import in a wide range of applications. Here, we detail, through experiment and computational simulation, the interfacial contact between four common traps and five commonly investigated surfaces encountered in explosives detection applications associated with airport security. The Young's modulus and hardness of four traps and seven substrates were measured using nanoindentation. These properties determine how deformation occurs when traps are applied for contact sampling of explosives. The nanoindentation data were analyzed using the Oliver-Pharr method, and an indenter area function was created using silicon and gold as the reference materials. The Young's moduli of the traps ranged from 0.2 to 8GPa, while those of the surfaces ranged from 0.5 to 4GPa. The hardness values of the traps ranged from 0.005 to 0.22GPa, while those of the surfaces ranged from 0.02 to 0.2GPa. For each of 20 scenarios (4 traps, 5 surfaces), six contact simulations were performed. In these contact simulations, the Greenwood-Willliamson microcontact model was used to represent the behavior of the asperities on the traps, while the Timoshenko Beam model was used to describe the macroscopic behavior of the bulk trap materials spanning the space between asperities. This combination of feature- and trap-scale modeling provides a more realistic description of the interfacial contact than either model applied individually. The calculated distributions of separation distances between the traps and surfaces when the traps were contacted with the surfaces under a normal load were compared to estimate the relative effectiveness of the traps at interrogating the topography of the surfaces. This method is proposed as a tool to guide the development of trap materials for surface sampling and surface cleaning applications. PMID:26836243

  15. Ion Implanted Passivated Contacts for Interdigitated Back Contacted Solar Cells

    SciTech Connect

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; Reedy, Robert; Bateman, Nicholas; Stradins, Pauls

    2015-06-14

    We describe work towards an interdigitated back contacted (IBC) solar cell utilizing ion implanted, passivated contacts. Formation of electron and hole passivated contacts to n-type CZ wafers using tunneling SiO2 and ion implanted amorphous silicon (a-Si) are described. P and B were ion implanted into intrinsic amorphous Si films at several doses and energies. A series of post-implant anneals showed that the passivation quality improved with increasing annealing temperatures up to 900 degrees C. The recombination parameter, Jo, as measured by a Sinton lifetime tester, was Jo ~ 14 fA/cm2 for Si:P, and Jo ~ 56 fA/cm2 for Si:B contacts. The contact resistivity for the passivated contacts, as measured by TLM patterns, was 14 milliohm-cm2 for the n-type contact and 0.6 milliohm-cm2 for the p-type contact. These Jo and pcontact values are encouraging for forming IBC cells using ion implantation to spatially define dopants.

  16. Low-coherence interferometer for contact lens surface metrology

    NASA Astrophysics Data System (ADS)

    Heideman, Kyle C.; Greivenkamp, John E.

    2016-03-01

    Contact lens performance depends on a number of lens properties. Many metrology systems have been developed to measure different aspects of a contact lens, but none test the surface figure in reflection to subwavelength accuracy. Interferometric surface metrology of immersed contact lenses is complicated by the close proximity of the surfaces, low surface reflectivity, and instability of the lens. An interferometer to address these issues was developed and is described here. The accuracy of the system is verified by comparison of glass reference sample measurements against a calibrated commercial interferometer. The described interferometer can accurately reconstruct large surface departures from spherical with reverse raytracing. The system is shown to have residual errors better than 0.05% of the measured surface departure for high slope regions. Measurements made near null are accurate to λ/20. Spherical, toric, and bifocal soft contact lenses have been measured by this system and show characteristics of contact lenses not seen in transmission testing. The measurements were used to simulate a transmission map that matches an actual transmission test of the contact lens to λ/18.

  17. Using lysimeters to test the Penman Monteith actual evapotranspiration.

    NASA Astrophysics Data System (ADS)

    Ben Asher, Jiftah; Volinski, Roman; Zilberman, Arkadi; Bar Yosef, Beni; Silber, Avner

    2015-04-01

    Differences in actual transpiration (ETa) of banana plants were quantified in a lysimeter experiment. ETA was computed using instantaneous data from two weighing lysimeters and compared to PM (Penman-Monteith) model for ETa. Two critical problems were faced in this test. A) Estimating canopy and aerodynamic resistances ("rc" and "ra" respectively ) and B) converting the lysimeter changes in water volume ( LYv cm3 ) to ETa length units ( cm ). The two unknowns " rc" and "ra" were obtained from continuous measurements of the differences between canopy and air temperature (Tc - Ta). This difference was established by means of the infrared thermometry which was followed by numerical and analytical calculation of ETa using the modification suggested by R. Jackson to the PM model. The conversion of lysimeter volumetric units (LYv) to ETa length units was derived from the slope of cumulative LYv/ETa. This relationship was significantly linear (r2=0.97and 0.98.). Its slope was interpreted as "evaporating leaf area" which accounted for 1.8E4 cm2 in lysimeter 1 and 2.3E4 cm2.in lysimeter 2 . The comparison between LYv and PM model was acceptable even under very low ETa. The average of two lysimeters was 1.1mm/day (1.4 mm/day , LYv 1 and 0.8 LYv 2) while ETa calculated on the basis of PM model was 1.2 mm/day. It was concluded that although lysimeters are most accurate systems to measure ETa one of its disadvantages ( beside the high cost) is the volumetric output that in many cases should be supported by a one dimensional energy balance system. The PM model was found to be a reliable complementary tool to convert lysimeters volumetric output into conventional length units of ETa.

  18. Contact dermatitis to methyl methacrylate.

    PubMed

    Kassis, V; Vedel, P; Darre, E

    1984-07-01

    2 cases of contact dermatitis to methyl methacrylate monomer are presented. The patients are nurses who mixed bone cement at orthopedic operations. During the procedure, they used 2 pairs of gloves (latex). Butyl rubber gloves are recommended for methyl methacrylate monomer to avoid sensitization and/or cumulative irritant contact dermatitis on the hands. PMID:6204812

  19. Contact sensitization in the elderly.

    PubMed

    Balato, Anna; Balato, Nicola; Di Costanzo, Luisa; Ayala, Fabio

    2011-01-01

    Contact dermatitis from irritant and allergic sources is the reason for 6% to 10% of all dermatologic visits with considerable morbidity and economic impact. Allergic contact dermatitis is a T-cell-mediated inflammatory reaction and develops in predisposed individuals as a consequence of environmental exposure to allergens. Aging is correlated with the rate and type of contact sensitization because of "immunosenescence." The number of old people is growing around the world. This contribution reviews the main findings from published epidemiologic studies on contact allergy in elderly populations. In all examined studies, patch testing was performed in patients with cutaneous manifestations possibly related to contact dermatitis; the prevalence of contact dermatitis in the elderly was from 33% to 64%. Establishing the most frequent allergens responsible for allergic contact dermatitis in the elderly is a hard task. The commonest allergens reported were nickel sulfate, fragrance mix, diamino diphenylmethane, lanolin alcohols, paraben mix, Euxyl K400, quinoline mix, and balsam of Peru. We emphasize that allergens surveillance is needed to realize an "elderly series" for having a useful adjunct to contact allergy that may help the treatment of each patient. PMID:21146728

  20. Contact modeling for robotics applications

    SciTech Connect

    Lafarge, R.A.; Lewis, C.

    1998-08-01

    At Sandia National Laboratories (SNL), the authors are developing the ability to accurately predict motions for arbitrary numbers of bodies of arbitrary shapes experiencing multiple applied forces and intermittent contacts. In particular, the authors are concerned with the simulation of systems such as part feeders or mobile robots operating in realistic environments. Preliminary investigation of commercial dynamics software packages led them to the conclusion that they could use commercial software to provide everything they needed except for the contact model. They found that ADAMS best fit their needs for a simulation package. To simulate intermittent contacts, they need collision detection software that can efficiently compute the distances between non-convex objects and return the associated witness features. They also require a computationally efficient contact model for rapid simulation of impact, sustained contact under load, and transition to and from contact conditions. This paper provides a technical review of a custom hierarchical distance computation engine developed at Sandia, called the C-Space Toolkit (CSTk). In addition, they describe an efficient contact model using a non-linear damping term developed by SNL and Ohio State. Both the CSTk and the non-linear damper have been incorporated in a simplified two-body testbed code, which is used to investigate how to correctly model the contact using these two utilities. They have incorporated this model into the ADAMS software using the callable function interface. An example that illustrates the capabilities of the 9.02 release of ADAMS with their extensions is provided.

  1. CHARACTERIZING HUMAN CONTACT WITH SEDIMENT

    EPA Science Inventory

    People contact sediment during a variety of activities such as fishing, wading and boating. A number of default assumptions are used today to characterize dermal contact with sediments in terms of magnitude, frequency and duration. The accuracy of these default values are widel...

  2. Tobacco-induced contact dermatitis.

    PubMed

    Bonamonte, Domenico; Vestita, Michelangelo; Filoni, Angela; Mastrolonardo, Mario; Angelini, Gianni; Foti, Caterina

    2016-06-01

    Tobacco and tobacco smoke are strongly associated with various skin conditions, among which contact dermatitis is of prime importance. The aetiological and clinical aspects vary according to the different tobacco production and processing steps. Contact dermatitis is frequent in tobacco harvesters, curers and cigar makers, whereas it rarely affects smokers and, only exceptionally, cigarette packaging workers. The skin sites involved also vary, according to whether the exposure is occupational or non-occupational. Tobacco contact irritation is far more frequent than contact allergy. The sensitizing compound in tobacco is unknown; nicotine, while highly toxic, does not seem to cause sensitization, except in rare cases. Besides natural substances, several compounds are added to tobacco during processing and manufacturing. For this reason, identifying the aetiological factors is exceedingly difficult. Another important aspect to take into account is the co-causative role of tobacco in eliciting or exacerbating contact dermatitis in response to other agents, occupational or extra-occupational. PMID:27020490

  3. Estimation of Thermal Contact Resistance Using Ultrasonic Waves

    NASA Astrophysics Data System (ADS)

    Cong, P. Z.; Zhang, X.; Fujii, M.

    2006-01-01

    In this paper, numerical simulations of both the three-dimensional heat conduction and two-dimensional elastic wave propagation at the interface of contact solids have been carried out. Numerical results of heat conduction simulations show that both the true contact area and thermal contact conductance increase linearly with an increase in the contact pressure. Numerical results of the ultrasonic wave propagation show that the intensity of a transmitted wave is very weak but depends clearly on the contact pressure. On the other hand, the intensity of reflected wave amounts to more than 99% of the standard reflected wave that results from the case of one cylindrical specimen without contact. However, the intensity of the modified reflected wave defined by the difference between the reflected wave and standard reflected wave shows the same tendency as that of the transmitted wave. The intensities of both transmitted and modified reflected waves could be expressed by the same power function of the contact pressure. By comparing the results of heat conduction with those of ultrasonic propagation calculations, a power functional correlation between the thermal contact conductance and transmitted or modified reflected intensity has been obtained. Using this correlation, it will be possible to estimate the thermal contact conductance between two solids through measuring the intensity of either reflected or transmitted ultrasonic waves.

  4. Safety of patients--actual problem of modern medicine (review).

    PubMed

    Tsintsadze, Neriman; Samnidze, L; Beridze, T; Tsintsadze, M; Tsintsadze, Nino

    2011-09-01

    Safety of patients is actual problem of up-to-date medicine. The current successful treatment of various sicknesses is achieved by implementation in clinical practice such medical preparations (medications), which are characterized with the high therapeutic activity, low toxicity and prolonged effects. In spite of evidence of the pharmacotherapeutical advances, the frequency of complications after medication has grown - that is why the safety of patients is the acute actual problem of medicine and ecological state of human population today. PMID:22156680

  5. Implications of the contact radius to line step (CRLS) ratio in AFM for nanotribology measurements.

    PubMed

    Helt, James M; Batteas, James D

    2006-07-01

    Investigating the mechanisms of defect generation and growth at surfaces on the nanometer scale typically requires high-resolution tools such as the atomic force microscope (AFM). To accurately assess the kinetics and activation parameters of defect production over a wide range of loads (F(z)), the AFM data should be properly conditioned. Generally, AFM wear trials are performed over an area defined by the length of the slow (L(sscan)) and fast scan axes. The ratio of L(sscan) to image resolution (res, lines per image) becomes an important experimental parameter in AFM wear trials because it defines the magnitude of the line step (LS = L(sscan)/res), the distance the AFM tip steps along the slow scan axis. Comparing the contact radius (a) to the line step (LS) indicates that the overlap of successive scans will result unless the contact radius-line step ratio (CRLS) is < or =(1)/(2). If this relationship is not considered, then the scan history (e.g., contact frequency) associated with a single scan is not equivalent at different loads owing to the scaling of contact radius with load (a proportional variant F(z)(1/3)). Here, we present a model in conjunction with empirical wear tests on muscovite mica to evaluate the effects of scan overlap on surface wear. Using the Hertz contact mechanics definition of a, the CRLS model shows that scan overlap pervades AFM wear trials even under low loads. Such findings indicate that simply counting the number of scans (N(scans)) in an experiment underestimates the full history conveyed to the surface by the tip and translates into an error in the actual extent to which a region on the surface is contacted. Utilizing the CRLS method described here provides an approach to account for image scan history accurately and to predict the extent of surface wear. This general model also has implications for any AFM measurement where one wishes to correlate scan-dependent history to image properties as well as feature resolution in scanned

  6. Differences between Actual and Perceived Student Norms: An Examination of Alcohol Use, Drug Use, and Sexual Behavior

    ERIC Educational Resources Information Center

    Martens, Matthew P.; Page, Jennifer C.; Mowry, Emily S.; Damann, Krista M.; Taylor, Kari K.; Cimini, M. Dolores

    2006-01-01

    Researchers in the social norms area have previously focused primarily on alcohol consumption, paying comparatively less attention to drug use and sexual behavior. The major purposes of this study were to (1) compare perceptions of peer norms in the areas of alcohol use, drug use, and sexual behavior with actual behavior and (2) determine if a…

  7. On the downscaling of actual evapotranspiration maps based on combination of MODIS and landsat-based actual evapotranspiration estimates

    USGS Publications Warehouse

    Singh, Ramesh K.; Senay, Gabriel B.; Velpuri, Naga Manohar; Bohms, Stefanie; Verdin, James P.

    2014-01-01

     Downscaling is one of the important ways of utilizing the combined benefits of the high temporal resolution of Moderate Resolution Imaging Spectroradiometer (MODIS) images and fine spatial resolution of Landsat images. We have evaluated the output regression with intercept method and developed the Linear with Zero Intercept (LinZI) method for downscaling MODIS-based monthly actual evapotranspiration (AET) maps to the Landsat-scale monthly AET maps for the Colorado River Basin for 2010. We used the 8-day MODIS land surface temperature product (MOD11A2) and 328 cloud-free Landsat images for computing AET maps and downscaling. The regression with intercept method does have limitations in downscaling if the slope and intercept are computed over a large area. A good agreement was obtained between downscaled monthly AET using the LinZI method and the eddy covariance measurements from seven flux sites within the Colorado River Basin. The mean bias ranged from −16 mm (underestimation) to 22 mm (overestimation) per month, and the coefficient of determination varied from 0.52 to 0.88. Some discrepancies between measured and downscaled monthly AET at two flux sites were found to be due to the prevailing flux footprint. A reasonable comparison was also obtained between downscaled monthly AET using LinZI method and the gridded FLUXNET dataset. The downscaled monthly AET nicely captured the temporal variation in sampled land cover classes. The proposed LinZI method can be used at finer temporal resolution (such as 8 days) with further evaluation. The proposed downscaling method will be very useful in advancing the application of remotely sensed images in water resources planning and management.

  8. Carbon dioxide fixation by microalgae photosynthesis using actual flue gas discharged from a boiler

    SciTech Connect

    Matsumoto, Hiroyo; Shioji, Norio; Hamasaki, Akihiro

    1995-12-31

    To mitigate CO{sub 2} discharged from thermal power plants, studies on CO{sub 2} fixation by the photosynthesis of microalgae using actual exhaust gas have been carried out. The results are as follows: (1) A method is proposed for evaluating the maximum photosynthesis rate in the raceway cultivator using only the algal physical properties; (2) Outdoor cultivation tests taking actual flue gas were performed with no trouble or break throughout 1 yr using the strain collected in the test; (3) The produced microalgae is effective as solid fuel; and (4) The feasibility studies of this system were performed. The system required large land area, but the area is smaller than that required for other biomass systems, such as tree farms.

  9. Head-disk interface nanotribology for Tbit/inch2 recording densities: near-contact and contact recording

    NASA Astrophysics Data System (ADS)

    Vakis, Antonis I.; Polycarpou, Andreas A.

    2010-06-01

    In the effort to achieve Tbit/inch2 recording densities, thermal fly-height control (TFC) nanotechnology was developed to effectively reduce the clearance (which is of the order of a few nanometres) at the head-disk interface (HDI) of hard-disk drives. In this work, we present a model of the HDI that can predict the dynamic flying and nanotribological contacting behaviour, allowing for accurate predictions and characterization of the operating regime as a function of TFC actuation. A geometric model for TFC is presented and an improved definition of contact at the interface is developed in the presence of nanoscale topographical roughness and dynamic microwaviness. A new methodology is proposed for the calculation of the nominal area of contact, which affects both near- and at-contact behaviour, while the stiffening of the air bearing force with TFC actuation is also accounted for. Slider behaviour is analysed by quantifying the approach, jump-to-contact, lubricant and solid contact regimes of operation and identifying the critical and optimum TFC actuations. The feasibility of near-contact, light molecularly thin lubricant contact versus solid contact recording is explored under the effect of the interfacial forces and stresses present at the HDI. The clearance and the state of vibrations are analysed and design guidelines are proposed for improved performance.

  10. Solving conformal contacts using multi-Hertzian techniques

    NASA Astrophysics Data System (ADS)

    Pascal, Jean-Pierre; Soua, Brahim

    2016-06-01

    Recently, publications aiming at wheel-rail contact surveys let readers think that multi-Hertzian methods present severe drawbacks with respect to 'virtual penetration' methods. These surveys criticise multi-Hertzian solutions mainly because presenting 'larger contacts overlaps' and 'frequent secondary contacts near the border of the first contact', both obvious geometric possibilities of which the practical occurrence and eventual inconvenience would remain purely theoretical unless established over definite methods demonstrating poor practical results. Recent surveys all quote Piotrowski-Chollet 2005 survey of wheel-rail contact models that attempted to illustrate defective multi-Hertzian techniques by concentrating on the method initiated by Sauvage in the 1990s and further developed by Pascal. The 2005 paper not only gives no evidence of practical inconveniences of Sauvage's method but also confuses static geometric contact overlaps with the dynamical overlapping of forces. In reality it mixes Sauvage method up with a quite different technique. Thus a clarification is now necessary by reminding what the proper Sauvage technique really is and by showing some of its practical successful applications. The present paper, focusing on determination of normal contact forces in conformal situations, intends to explain clearly the advantages of the unequivocal localisation of secondary ellipses in that multi-Hertzian method which has been developed in INRETS VOCO codes in the 1990s and successfully used by SNCF and ALSTOM in the INRETS-SNCF code, VOCODYM, and later in Pascal's online calculation of railway elastic contacts code. It proved its effectiveness for studying freight wagons derailments as well as rail wear and head-check, unrounded wheels wear, high-speed lines' deformations or TGV comfort. While simulating American ACELA trainsets' behaviour on the US North-East Corridor tracks, prior to actual tests, as part of the commercial contract. It has been also a

  11. Thermal contact conductance of actuated interfaces

    NASA Astrophysics Data System (ADS)

    Song, Woo-Bin; Sutton, Michael S.; Talghader, Joseph J.

    2002-08-01

    The thermal contact conductance (TCC) of microactuated mechanical interfaces has been characterized using an electronic technique, where micromachined test structures were heated with a current and the TCC was inferred from the change in resistance. For every device tested, the TCC was higher in vacuum than in air. This is in stark contrast to the behavior of bulk interfaces, and several experiments suggest that it may be the result of a decreased solid-solid contact area in air caused by the pressure of the interstitial gas. The average effective TCC of a polysilicon/nitride interface brought together by electrostatic actuation varies about values of 6.0 x104 W/(K m2) in air and 9.5 x104 W/(K m2) under vacuum for applied pressures of 1 MPa. These values are significantly higher than commonly reported for nonmetallic materials and probably reflect the very smooth surfaces of deposited thin films.

  12. Electrical contact arrangement for a coating process

    DOEpatents

    Kabagambe, Benjamin; McCamy, James W; Boyd, Donald W

    2013-09-17

    A protective coating is applied to the electrically conductive surface of a reflective coating of a solar mirror by biasing a conductive member having a layer of a malleable electrically conductive material, e.g. a paste, against a portion of the conductive surface while moving an electrodepositable coating composition over the conductive surface. The moving of the electrodepositable coating composition over the conductive surface includes moving the solar mirror through a flow curtain of the electrodepositable coating composition and submerging the solar mirror in a pool of the electrodepositable coating composition. The use of the layer of a malleable electrically conductive material between the conductive member and the conductive surface compensates for irregularities in the conductive surface being contacted during the coating process thereby reducing the current density at the electrical contact area.

  13. Thermal contact conductance of pressed contacts at low temperatures

    NASA Astrophysics Data System (ADS)

    Sunil Kumar, S.; Ramamurthi, K.

    2004-10-01

    The influence of variations of interface temperature in the range 50-300 K on the thermal contact conductance between aluminium and stainless steel joints was determined. Predictions were done by modeling the deformation at the interface for different values of surface finish and contact pressure over the range of interface temperatures. Both elastic and plastic deformation was considered. Experiments were carried out in a closed loop cryostat and the results were shown to compare well with the predictions. A reduction of the interface temperature resulted in a smaller value of thermal contact conductance. Interfacial pressure variation had much lower influence at the smaller value of temperatures. The role of surface roughness at the contact was also seen to be less significant at lower interface temperatures and the zone of hysteresis was smaller. A correlation was developed for estimating thermal contact conductance at joints over this temperature range. An explicit dependence of contact conductance on temperature was not seen to be necessary as long as the changes in the hardness and thermal conductivity of the material with temperature are incorporated in the correlation.

  14. Allergic contact dermatitis from ketoconazole.

    PubMed

    Liu, Jing; Warshaw, Erin M

    2014-09-01

    Ketoconazole is a widely used imidazole antifungal agent. True contact allergy to topical ketoconazole is rare, and few cases of patients with contact allergy to ketoconazole have been reported. We present the case of a patient with a history of undiagnosed recurrent dermatitis who developed acute facial swelling and pruritus after using ketoconazole cream and shampoo for the treatment of seborrheic dermatitis. Patch testing revealed true contact allergy to ketoconazole without cross-reactivity to 4 other imidazole antifungals. Review of the patient's medical record suggested that prior incidences of dermatitis might have been due to ketoconazole exposure. When the patient avoided this imidazole agent, the dermatitis resolved. PMID:25279470

  15. Carrier Selective, Passivated Contacts for High Efficiency Silicon Solar Cells based on Transparent Conducting Oxides

    SciTech Connect

    Young, David L.; Nemeth, William; Grover, Sachit; Norman, Andrew; Yuan, Hao-Chih; Lee, Benjamin G.; LaSalvia, Vincenzo; Stradins, Paul

    2014-01-01

    We describe the design, fabrication and results of passivated contacts to n-type silicon utilizing thin SiO2 and transparent conducting oxide layers. High temperature silicon dioxide is grown on both surfaces of an n-type wafer to a thickness <50 Å, followed by deposition of tin-doped indium oxide (ITO) and a patterned metal contacting layer. As deposited, the thin-film stack has a very high J0,contact, and a non-ohmic, high contact resistance. However, after a forming gas anneal, the passivation quality and the contact resistivity improve significantly. The contacts are characterized by measuring the recombination parameter of the contact (J0,contact) and the specific contact resistivity (ρcontact) using a TLM pattern. The best ITO/SiO2 passivated contact in this study has J0,contact = 92.5 fA/cm2 and ρcontact = 11.5 mOhm-cm2. These values are placed in context with other passivating contacts using an analysis that determines the ultimate efficiency and the optimal area fraction for contacts for a given set of (J0,contact, ρcontact) values. The ITO/SiO2 contacts are found to have a higher J0,contact, but a similar ρcontact compared to the best reported passivated contacts.

  16. Acoustic Microscopy for Visualization and Evaluation of Ceramic-ceramic Contact Zone

    NASA Astrophysics Data System (ADS)

    Morokov, E. S.; Levin, V. M.; Petronyuk, Yu. S.; Podzorova, L. I.; Il'Icheva, A. A.; Lebedenko, I. Yu.; Anisimova, S. V.

    Impulse acoustic microscopy technique has been applied for investigation of features of ceramic-ceramic contact zone. At the interface the method allows to identified and localized detachment and extended partial contact area (kissing contact), shown distribution of the thickness of the interlayer and its homogeneity.

  17. Capteur Tridimensionnel Sans Contact

    NASA Astrophysics Data System (ADS)

    Magnant, D.

    1986-07-01

    Three-dimensionnal measurements on human body using a scanning laser beam. The active optical apparatus principle and the image data processing giving three dimensional informations of complex forms is presented. The output is given in terms of one or several files of real coordinates. The basic components of this system are : A light-sheet which is generated by a laser source and, the optical sensors (cameras) with corresponding hard-soft extractor; This 3D sensorial system is especially adapted to partial or total acquisitions of body coordinates. The main advantages are : - Vision and measurement capability of complete accessible contours without shadow areas. - The real time data acquisition and scanning of the object in a few seconds. - The access to distance measurements between significant points. - The presently obtained accuracy is better than 1/1000 in relatives units and lower than one MM absolute. - Physically stuck markers on body are not necessary. - The monochromaticity of the laser light source allows the use of a color filter over the detector (camera) for ambient light rejection. - The fully programmable capability for any use, allows the adaptation to a large variety of particular cases. - The hardware open system offers many options. - The hard-soft tool is designed for auto-calibration operation. - The system offers easy connection to a host computer or a production robot.

  18. Carbon-Nanotube-Enhanced Thermal Contactor in Low Contact Pressure Region

    NASA Astrophysics Data System (ADS)

    Tsukamoto, Takashiro; Esashi, Masayoshi; Tanaka, Shuji

    2010-07-01

    We first demonstrated considerable reduction of thermal contact resistance (TCR) of a bending thermal contactor in microscale using carbon nanotubes (CNTs). TCR reduction using CNTs were previously reported with flat contact surface, but the thermal contact surfaces of actual microdevices often bend because of their residual and thermal stress. We evaluated both flat and bending contact surfaces to apply this method for a variety of applications. The TCR reduction is observed not only with a flat contact surface but also a bending surface. A bending micro thermal contactor with a plasma-enhanced chemical vapor deposition (PECVD)-grown 10 µm long “CNT carpet” shows a TCR of ca. 600 mm2 K/W at a contact pressure of 20 kPa, which is about 1/10 to the TCR of the reference contactor without “CNT carpet”. This technique is useful for micro thermal devices such as micro thermal switch.

  19. The effect of base station contact on ambulance destination.

    PubMed

    Neely, K; Norton, R; Bartkus, E; Schriver, J

    1990-08-01

    Concern has been raised that a single medical control base station serving a metropolitan area may preferentially divert ambulance patients to the base station hospital. Such concern may discourage the development of regional medical control systems. During the first six months of 1988, a retrospective cross-sectional analysis was made of all advanced life support (ALS) ambulance transports and all contacts to the single base station, known as Medical Resource Hospital (MRH). Destinations of all ALS ambulance calls dispatched through the county's 911 dispatch center were analyzed to determine whether the destinations were affected by MRH contact. There were 12,396 transports to 17 area hospitals with 1,272 (10.3%) of these requiring MRH contact. We hypothesized that if MRH contact did not affect destination, the proportion of all non-MRH ALS ambulance patients received by each hospital from the 911-dispatched group would equal the proportion of patients received by each hospital after MRH contact. Five hospitals received a statistically significant (P less than .003) different percentage of MRH contact patients than their proportion of 911-dispatched patients would have predicted. The three that received more were community hospitals in outlying areas. The remaining two were a large referral hospital and a smaller community hospital located in the urban area. The MRH hospital did not have a significantly different percentage of 911-dispatched patients after MRH contact. Similarly, destinations of specific ALS ambulances (two serving in the MRH ambulance catchment area and four in distant catchment areas) were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2372174

  20. Connector contact-ring bus

    NASA Technical Reports Server (NTRS)

    Ligon, J.

    1976-01-01

    Use of device eliminates crimp connectors and ferrules, resulting in compact termination assembly and efficient use of back-shell space. Pair of insulator rings, one at each end of assembly, provides spacing between disc caps and contact rings.

  1. Racial Disparity in Police Contacts

    PubMed Central

    Crutchfield, Robert D.; Haggerty, Kevin P.; McGlynn, Anne; Catalano, Richard F.

    2013-01-01

    Criminologists agree the race disparity in arrests cannot be fully explained by differences in criminal behavior. We examine social environment factors that may lead to racial differences in police contact in early adolescence, including family, peers, school, and community. Data are from 331 8th-grade students. Blacks were almost twice as likely as Whites to report a police contact. Blacks reported more property crime but not more violent crime than Whites. Police contacts were increased by having a parent who had been arrested, a sibling involved in criminal activity, higher observed reward for negative behavior, having school disciplinary actions, and knowing adults who engaged in substance abuse or criminal behavior. Race differences in police contacts were partially attributable to more school discipline. PMID:24363956

  2. Transition metal contacts to graphene

    SciTech Connect

    Politou, Maria De Gendt, Stefan; Heyns, Marc; Asselberghs, Inge; Radu, Iuliana; Conard, Thierry; Richard, Olivier; Martens, Koen; Huyghebaert, Cedric; Tokei, Zsolt; Lee, Chang Seung; Sayan, Safak

    2015-10-12

    Achieving low resistance contacts to graphene is a common concern for graphene device performance and hybrid graphene/metal interconnects. In this work, we have used the circular Transfer Length Method (cTLM) to electrically characterize Ag, Au, Ni, Ti, and Pd as contact metals to graphene. The consistency of the obtained results was verified with the characterization of up to 72 cTLM structures per metal. Within our study, the noble metals Au, Ag and Pd, which form a weaker bond with graphene, are shown to result in lower contact resistance (Rc) values compared to the more reactive Ni and Ti. X-ray Photo Electron Spectroscopy and Transmission Electron Microscopy characterization for the latter have shown the formation of Ti and Ni carbides. Graphene/Pd contacts show a distinct intermediate behavior. The weak carbide formation signature and the low Rc values measured agree with theoretical predictions of an intermediate state of weak chemisorption of Pd on graphene.

  3. Pose and motion from contact

    SciTech Connect

    Jia, Y.B.; Erdmann, M.

    1999-05-01

    In the absence of vision, grasping an object often relies on tactile feedback from the fingertips. As the finger pushes the object, the fingertip can feel the contact point move. If the object is known in advance, from this motion the finger may infer the location of the contact point on the object, and thereby, the object pose. This paper primarily investigates the problem of determining the pose (orientation and position) and motion (velocity and angular velocity) of a planar object with known geometry from such contact motion generated by pushing. A dynamic analysis of pushing yields a nonlinear system that relates through contact the object pose and motion to the finger motion. The contact motion on the fingertip thus encodes certain information about the object pose. Nonlinear observability theory is employed to show that such information is sufficient for the finger to observe not only the pose, but also the motion of the object. Therefore, a sensing strategy can be realized as an observer of the nonlinear dynamic system. Two observers are subsequently introduced. The first observer, based on the work of Gautheir, Hammouri, and Othman (1992), has its gain determined by the solution of a Lyapunov-like equation; it can be activated at any time instant during a push. The second observer, based on Newton`s method, solves for the initial (motionless) object pose from three intermediate contact points during a push. Under the Coulomb-friction model, the paper deals with support friction in the plane and/or contact friction between the finger and the object. Extensive simulations have been done to demonstrate the feasibility of the two observers. Preliminary experiments (with an Adept robot) have also been conducted. A contact sensor has been implemented using strain gauges.

  4. Method for lubricating contacting surfaces

    DOEpatents

    Dugger, Michael T.; Ohlhausen, James A.; Asay, David B.; Kim, Seong H.

    2011-12-06

    A method is provided for tribological lubrication of sliding contact surfaces, where two surfaces are in contact and in motion relative to each other, operating in a vapor-phase environment containing at least one alcohol compound at a concentration sufficiently high to provide one monolayer of coverage on at least one of the surfaces, where the alcohol compound continuously reacts at the surface to provide lubrication.

  5. Discrete-contact nanowire photovoltaics

    NASA Astrophysics Data System (ADS)

    Chitambar, Michelle J.; Wen, Wen; Maldonado, Stephen

    2013-11-01

    A series of finite-element simulations have been performed to assess the operational characteristics of a new semiconductor nanowire solar cell design operating under high-level injection conditions. Specifically, the steady-state current-voltage behavior of a cylindrical silicon (Si) nanowire with a series of discrete, ohmic-selective contacts under intense sunlight illumination was investigated. The scope of the analysis was limited to only the factors that impact the net internal quantum yield for solar to electricity conversion. No evaluations were performed with regards to optical light trapping in the modeled structures. Several aspects in a discrete-contact nanowire device that could impact operation were explored, including the size and density of ohmic-selective contacts, the size of the nanowire, the electronic quality and conductivity of the nanowire, the surface defect density of the nanowire, and the type of ohmic selectivity employed at each contact. The analysis showed that there were ranges of values for each parameter that supported good to excellent photoresponses, with certain combinations of experimentally attainable material properties yielding internal energy conversion efficiencies at the thermodynamic limit for a single junction cell. The merits of the discrete-contact nanowire cell were contrasted with "conventional" nanowire photovoltaic cells featuring a uniform conformal contact and also with planar point-contact solar cells. The unique capacity of the discrete-contact nanowire solar cell design to operate at useful energy conversion efficiencies with low quality semiconductor nanowires (i.e., possessing short charge-carrier lifetimes) with only light doping is discussed. This work thus defines the impetus for future experimental work aimed at developing this photovoltaic architecture.

  6. Novel vertical silicon photodiodes based on salicided polysilicon trenched contacts

    SciTech Connect

    Kaminski, Yelena; Shauly, Eitan; Paz, Yaron

    2015-12-07

    The classical concept of silicon photodiodes comprises of a planar design characterized by heavily doped emitters. Such geometry has low collection efficiency of the photons absorbed close to the surface. An alternative, promising, approach is to use a vertical design. Nevertheless, realization of such design is technologically challenged, hence hardly explored. Herein, a novel type of silicon photodiodes, based on salicided polysilicon trenched contacts, is presented. These contacts can be prepared up to 10 μm in depth, without showing any leakage current associated with the increase in the contact area. Consequently, the trenched photodiodes revealed better performance than no-trench photodiodes. A simple two dimensional model was developed, allowing to estimate the conditions under which a vertical design has the potential to have better performance than that of a planar design. At large, the deeper the trench is, the better is the vertical design relative to the planar (up to 10 μm for silicon). The vertical design is more advantageous for materials characterized by short diffusion lengths of the carriers. Salicided polysilicon trenched contacts open new opportunities for the design of solar cells and image sensors. For example, these contacts may passivate high contact area buried contacts, by virtue of the conformity of polysilicon interlayer, thus lowering the via resistance induced recombination enhancement effect.

  7. Damping in viscoelastic contacts under combined normal and tangential oscillation

    NASA Astrophysics Data System (ADS)

    Popov, Mikhail; Li, Qiang; Popov, Nikita

    2015-10-01

    Damping in the contact of a rigid conical indenter with a viscoelastic half-space under superimposed normal and tangential oscillation is considered, with perfect sticking in the contact. The viscoelastic half-space is modeled with the Kelvin material. The energy dissipated per oscillation cycle is determined numerically in the framework of the method of dimensionality reduction (MDR). A particular focus of the present study is the influence of the changes in contact area due to the normal oscillation on the tangential component of dissipation.

  8. Estimation of discretization errors in contact pressure measurements.

    PubMed

    Fregly, Benjamin J; Sawyer, W Gregory

    2003-04-01

    Contact pressure measurements in total knee replacements are often made using a discrete sensor such as the Tekscan K-Scan sensor. However, no method currently exists for predicting the magnitude of sensor discretization errors in contact force, peak pressure, average pressure, and contact area, making it difficult to evaluate the accuracy of such measurements. This study identifies a non-dimensional area variable, defined as the ratio of the number of perimeter elements to the total number of elements with pressure, which can be used to predict these errors. The variable was evaluated by simulating discrete pressure sensors subjected to Hertzian and uniform pressure distributions with two different calibration procedures. The simulations systematically varied the size of the sensor elements, the contact ellipse aspect ratio, and the ellipse's location on the sensor grid. In addition, contact pressure measurements made with a K-Scan sensor on four different total knee designs were used to evaluate the magnitude of discretization errors under practical conditions. The simulations predicted a strong power law relationship (r(2)>0.89) between worst-case discretization errors and the proposed non-dimensional area variable. In the total knee experiments, predicted discretization errors were on the order of 1-4% for contact force and peak pressure and 3-9% for average pressure and contact area. These errors are comparable to those arising from inserting a sensor into the joint space or truncating pressures with pressure sensitive film. The reported power law regression coefficients provide a simple way to estimate the accuracy of experimental measurements made with discrete pressure sensors when the contact patch is approximately elliptical. PMID:12600352

  9. Solution-Assisted Optical Contacting

    NASA Technical Reports Server (NTRS)

    Shaddock, Daniel; Abramovici, Alexander

    2004-01-01

    A modified version of a conventional optical-contact procedure has been found to facilitate alignment of optical components. The optical-contact procedure (called simply optical contacting in the art) is a standard means of bonding two highly polished and cleaned glass optical components without using epoxies or other adhesives. In its unmodified form, the procedure does not involve the use of any foreign substances at all: components to be optically contacted are dry. The main disadvantage of conventional optical contacting is that it is difficult or impossible to adjust the alignment of the components once they have become bonded. In the modified version of the procedure, a drop of an alcohol-based optical cleaning solution (isopropyl alcohol or similar) is placed at the interface between two components immediately before putting the components together. The solution forms a weak bond that gradually strengthens during a time interval of the order of tens of seconds as the alcohol evaporates. While the solution is present, the components can be slid, without loss of contact, to perform fine adjustments of their relative positions. After about a minute, most of the alcohol has evaporated and the optical components are rigidly attached to each other. If necessary, more solution can be added to enable resumption or repetition of the adjustment until the components are aligned to the required precision.

  10. Mechanisms of rolling contact spalling

    NASA Technical Reports Server (NTRS)

    Kumar, A. M.; Kulkarni, S. M.; Bhargava, V.; Hahn, G. T.; Rubin, C. A.

    1987-01-01

    The results of a study aimed at analyzing the mechanical material interactions responsible for rolling contact spalling of the 440 C steel, high pressure oxygen turbopump bearings are presented. A coupled temperature displacement finite element analysis of the effects of friction heating under the contact is presented. The contact is modelled as a stationary, heat generating, 2 dimensional indent in an elastic perfectly plastic half-space with heat fluxes up to 8.6 x 10000 KW/m sq comparable to those generated in the bearing. Local temperatures in excess of 1000 C are treated. The calculations reveal high levels of residual tension after the contact is unloaded and cools. Efforts to promote Mode 2/Mode 3 fatigue crack growth under cyclic torsion in hardened 440 C steel are described. Spalls produced on 440 C steel by a 3 ball/rod rolling contact testing machine were studied with scanning microscopy. The shapes of the cyclic, stress strain hysteresis loops displayed by hardened 440 C steel in cyclic torsion at room temperature are defined for the plastic strain amplitudes encountered in rolling/sliding contact. Results of these analyses are discussed in detail.

  11. Diabetes and contact lens wear.

    PubMed

    O'Donnell, Clare; Efron, Nathan

    2012-05-01

    The literature suggests that diabetic patients may have altered tear chemistry and tear secretion as well as structural and functional changes to the corneal epithelium, endothelium and nerves. These factors, together with a reported increased incidence of corneal infection, suggest that diabetic patients may be particularly susceptible to developing ocular complications during contact lens wear. Reports of contact lens-induced complications in diabetic patients do exist, although a number of these reports concern patients with advanced diabetic eye disease using lenses on an extended wear basis. Over the past decade or so, there have been published studies documenting the response of the diabetic eye to more modern contact lens modalities. The results of these studies suggest that contact lenses can be a viable mode of refractive correction for diabetic patients. Furthermore, new research suggests that the measurement of tear glucose concentration could, in future, be used to monitor metabolic control non-invasively in diabetic patients. This could be carried out using contact lenses manufactured from hydrogel polymers embedded with glucose-sensing agents or nanoscale digital electronic technology. The purpose of this paper is to review the literature on the anterior ocular manifestations of diabetes, particularly that pertaining to contact lens wear. PMID:22537249

  12. Experimental philosophy of actual and counterfactual free will intuitions.

    PubMed

    Feltz, Adam

    2015-11-01

    Five experiments suggested that everyday free will and moral responsibility judgments about some hypothetical thought examples differed from free will and moral responsibility judgments about the actual world. Experiment 1 (N=106) showed that free will intuitions about the actual world measured by the FAD-Plus poorly predicted free will intuitions about a hypothetical person performing a determined action (r=.13). Experiments 2-5 replicated this result and found the relations between actual free will judgments and free will judgments about hypothetical determined or fated actions (rs=.22-.35) were much smaller than the differences between them (ηp(2)=.2-.55). These results put some pressure on theoretical accounts of everyday intuitions about freedom and moral responsibility. PMID:26126174

  13. Review of the thermal contact conductance of junctions with metallic coatings and films

    NASA Astrophysics Data System (ADS)

    Lambert, M. A.; Fletcher, L. S.

    1993-10-01

    The reliability of standard electronic modules may be improved by decreasing overall module temperature. This may be accomplished by enhancing the thermal contact conductance at the interface between the module frame guide rib and the card rail to which the module is clamped. The surface irregularities resulting from the machining or extruding of the components cause the true contact area to be much less than the apparent contact area, increasing the contact resistance. Some metallic coatings deform easily under load and increase the contact area and associated conductance. This investigation evaluates possible coatings and determines those most suitable for enhancing contact conductance based upon predictions using existing theories for thermal contact conductance of coated junctions.

  14. Crane-Load Contact Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Cox, Robert

    2005-01-01

    An electronic instrument has been developed as a prototype of a portable crane-load contact sensor. Such a sensor could be helpful in an application in which the load rests on a base in a horizontal position determined by vertical alignment pins (see Figure 1). If the crane is not positioned to lift the load precisely vertically, then the load can be expected to swing once it has been lifted clear of the pins. If the load is especially heavy, large, and/or fragile, it could hurt workers and/or damage itself and nearby objects. By indicating whether the load remains in contact with the pins when it has been lifted a fraction of the length of the pins, the crane-load contact sensor helps the crane operator determine whether it is safe to lift the load clear of the pins: If there is contact, then the load is resting against the sides of the pins and, hence, it may not be safe to lift; if contact is occasionally broken, then the load is probably not resting against the pins, so it should be safe to lift. It is assumed that the load and base, or at least the pins and the surfaces of the alignment holes in the load, are electrically conductive, so the instrument can use electrical contact to indicate mechanical contact. However, DC resistance cannot be used as an indicator of contact for the following reasons: The load and the base are both electrically grounded through cables (the load is grounded through the lifting cable of the crane) to prevent discharge of static electricity. In other words, the DC resistance between the load and the pins is always low, as though they were always in direct contact. Therefore, instead of DC resistance, the instrument utilizes the AC electrical impedance between the pins and the load. The signal frequency used in the measurement is high enough (.1 MHz) that the impedance contributed by the cables and the electrical ground network of the building in which the crane and the base are situated is significantly greater than the contact

  15. Performance evaluation of 24 ion exchange materials for removing cesium and strontium from actual and simulated N-Reactor storage basin water

    SciTech Connect

    Brown, G.N.; Carson, K.J.; DesChane, J.R.; Elovich, R.J.

    1997-09-01

    This report describes the evaluation of 24 organic and inorganic ion exchange materials for removing cesium and strontium from actual and simulated waters from the 100 Area 105 N-Reactor fuel storage basin. The data described in this report can be applied for developing and evaluating ion exchange pre-treatment process flowsheets. Cesium and strontium batch distribution ratios (K{sub d}`s), decontamination factors (DF), and material loadings (mmol g{sup -1}) are compared as a function of ion exchange material and initial cesium concentration. The actual and simulated N-Basin waters contain relatively low levels of aluminum, barium, calcium, potassium, and magnesium (ranging from 8.33E-04 to 6.40E-05 M), with slightly higher levels of boron (6.63E-03 M) and sodium (1.62E-03 M). The {sup 137}Cs level is 1.74E-06 Ci L-{sup 1} which corresponds to approximately 4.87E-10 M Cs. The initial Na/Cs ratio was 3.33E+06. The concentration of total strontium is 4.45E-06 M, while the {sup 90}Sr radioactive component was measured to be 6.13E-06 Ci L{sup -1}. Simulant tests were conducted by contacting 0.067 g or each ion exchange material with approximately 100 mL of either the actual or simulated N-Basin water. The simulants contained variable initial cesium concentrations ranging from 1.00E-04 to 2.57E- 10 M Cs while all other components were held constant. For all materials, the average cesium K{sub d} was independent of cesium concentration below approximately 1.0E-06 M. Above this level, the average cesium K{sub d} values decreased significantly. Cesium K{sub d} values exceeding 1.0E+07 mL g{sup -1} were measured in the simulated N-Basin water. However, when measured in the actual N-Basin water the values were several orders of magnitude lower, with a maximum of 1.24E+05 mL g{sup -1} observed.

  16. A Flawed Argument Against Actual Infinity in Physics

    NASA Astrophysics Data System (ADS)

    Perez Laraudogoitia, Jon

    2010-12-01

    In “Nonconservation of Energy and loss of Determinism II. Colliding with an Open Set” (2010) Atkinson and Johnson argue in favour of the idea that an actual infinity should be excluded from physics, at least in the sense that physical systems involving an actual infinity of component elements should not be admitted. In this paper I show that the argument Atkinson and Johnson use is erroneous and that an analysis of the situation considered by them is possible without requiring any type of rejection of the idea of infinity.

  17. Pilot Eye Scanning under Actual Single Pilot Instrument Flight

    NASA Astrophysics Data System (ADS)

    Rinoie, Kenichi; Sunada, Yasuto

    Operations under single pilot instrument flight rules for general aviation aircraft is known to be one of the most demanding pilot tasks. Scanning numerous instruments plays a key role for perception and decision-making during flight. Flight experiments have been done by a single engine light airplane to investigate the pilot eye scanning technique for IFR flights. Comparisons between the results by an actual flight and those by a PC-based flight simulator are made. The experimental difficulties of pilot eye scanning measurements during the actual IFR flight are discussed.

  18. Measuring The Contact Resistances Of Photovoltaic Cells

    NASA Technical Reports Server (NTRS)

    Burger, D. R.

    1985-01-01

    Simple method devised to measure contact resistances of photovoltaic solar cells. Method uses readily available equipment and applicable at any time during life of cell. Enables evaluation of cell contact resistance, contact-end resistance, contact resistivity, sheet resistivity, and sheet resistivity under contact.

  19. Solar cell with back side contacts

    DOEpatents

    Nielson, Gregory N; Okandan, Murat; Cruz-Campa, Jose Luis; Resnick, Paul J; Wanlass, Mark Woodbury; Clews, Peggy J

    2013-12-24

    A III-V solar cell is described herein that includes all back side contacts. Additionally, the positive and negative electrical contacts contact compoud semiconductor layers of the solar cell other than the absorbing layer of the solar cell. That is, the positive and negative electrical contacts contact passivating layers of the solar cell.

  20. Contact Lens-Related Eye Infections

    MedlinePlus

    ... Stories Español Eye Health / Eye Health A-Z Contact Lens-Related Eye Infections Sections Contact Lens-Related ... About Contact Lenses Proper Care of Contact Lenses Contact Lens-Related Eye Infections Written by: Kierstan Boyd ...

  1. RF Sputtering of Gold Contacts On Niobium

    NASA Technical Reports Server (NTRS)

    Barr, D. W.

    1983-01-01

    Reliable gold contacts are deposited on niobium by combination of RF sputtering and photolithography. Process results in structures having gold only where desired for electrical contact. Contacts are stable under repeated cycling from room temperature to 4.2 K and show room-temperature contact resistance as much as 40 percent below indium contacts made by thermalcompression bonding.

  2. Strontium and Actinide Separations from High Level Nuclear Waste Solutions using Monosodium Titanate - Actual Waste Testing

    SciTech Connect

    Peters, T.B.; Barnes, M.J.; Hobbs,D.T.; Walker, D.D.; Fondeur, F.F.; Norato, M.A.; Pulmano, R.L.; Fink, S.D.

    2005-11-01

    Pretreatment processes at the Savannah River Site will separate {sup 90}Sr, alpha-emitting and radionuclides (i.e., actinides) and {sup 137}Cs prior to disposal of the high-level nuclear waste. Separation of {sup 90}Sr and alpha-emitting radionuclides occurs by ion exchange/adsorption using an inorganic material, monosodium titanate (MST). Previously reported testing with simulants indicates that the MST exhibits high selectivity for strontium and actinides in high ionic strength and strongly alkaline salt solutions. This paper provides a summary of data acquired to measure the performance of MST to remove strontium and actinides from actual waste solutions. These tests evaluated the effects of ionic strength, mixing, elevated alpha activities, and multiple contacts of the waste with MST. Tests also provided confirmation that MST performs well at much larger laboratory scales (300-700 times larger) and exhibits little affinity for desorption of strontium and plutonium during washing.

  3. On the structure of contact binaries. I - The contact discontinuity

    NASA Technical Reports Server (NTRS)

    Shu, F. H.; Lubow, S. H.; Anderson, L.

    1976-01-01

    The problem of the interior structure of contact binaries is reviewed, and a simple resolution of the difficulties which plague the theory is suggested. It is proposed that contact binaries contain a contact discontinuity between the lower surface of the common envelope and the Roche lobe of the cooler star. This discontinuity is maintained against thermal diffusion by fluid flow, and the transition layer is thin to the extent that the dynamical time scale is short in comparison with the thermal time scale. The idealization that the transition layer has infinitesimal thickness allows a simple formulation of the structure equations which are closed by appropriate jump conditions across the discontinuity. The further imposition of the standard boundary conditions suffices to define a unique model for the system once the chemical composition, the masses of the two stars, and the orbital separation are specified.

  4. Reduced contact resistance in top-contact organic field-effect transistors by interface contact doping

    NASA Astrophysics Data System (ADS)

    Hou, Ji-Ling; Kasemann, Daniel; Widmer, Johannes; Günther, Alrun A.; Lüssem, Björn; Leo, Karl

    2016-03-01

    Emerging organic integrated electronics require capability of high speed and the compatibility with high-resolution structuring processes such as photolithography. When downscaling the channel length, the contact resistance is known to limit the performance of the short channel devices. In this report, orthogonal photolithography is used for the patterning of the source/drain electrodes of the organic field-effect transistors (OFETs) as well as the interface dopant insertion layers for further modifications of the contact resistance. Bottom-gate top-contact pentacene OFETs with different thicknesses of the p-dopant 2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile under the Au electrodes show a significant decrease in threshold voltage from -2.2 V to -0.8 V and in contact resistance from 55 k Ω cm to 10 k Ω cm by adding a 1 nm thin dopant interlayer. The influence of doping on charge carrier injection is directly visible in the temperature-dependent output characteristics and a charge-transfer activation energy of ˜20 meV is obtained. Our results provide a systematic study of interface contact doping and also show the connection between interface contact doping and improved charge carrier injection by the activation of charge transfer process.

  5. Theoretical and experimental investigation of the thermal contact resistance of a space-use deep groove ball bearing

    NASA Astrophysics Data System (ADS)

    Nakajima, Katsuhiko

    The thermal contact resistance between the balls and the inner and outer rings of a space-use ball bearing is investigated assuming that heat transfer between smooth contacting elements occurs through the elastic contact areas. It is also assumed that the stationary bearing sustains axial, radial or combined loads under a steady-state temperature condition. The shapes and sizes of the contact areas are calculated using the Hertzian theory. In particular, the contact force for the axial load is derived with careful consideration of the changes in the contact angle induced by elastic deformation at the contact area. The correlation between the test data and the calculated values confirms the validity of the prediction method for the thermal contact resistances between the elements of a dry bearing with smooth contact surfaces.

  6. Actualizing Concepts in Home Management: Proceedings of a National Conference.

    ERIC Educational Resources Information Center

    American Home Economics Association, Washington, DC.

    The booklet prints the following papers delivered at a national conference: Actualizing Concepts in Home Management: Decision Making, Dorothy Z. Price; Innovations in Teaching: Ergonomics, Fern E. Hunt; Relevant Concepts of Home Management: Innovations in Teaching, Kay P. Edwards; Standards in a Managerial Context, Florence S. Walker; Organizing:…

  7. 26 CFR 513.8 - Addressee not actual owner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... CONVENTIONS IRELAND Withholding of Tax § 513.8 Addressee not actual owner. (a) If any person with an address in Ireland who receives a dividend from a United States corporation with respect to which United... such reduced rate of 15 percent, such recipient in Ireland will withhold an additional amount of...

  8. Remote sensing estimates of actual evapotranspiration in an irrigation district

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate estimates of the spatial distribution of actual evapotranspiration (AET) are useful in hydrology, but can be difficult to obtain. Remote sensing provides a potential capability for routinely monitoring AET by combining remotely sensed surface temperature and vegetation cover observations w...

  9. Self Actualization of Females in an Experimental Orientation Program

    ERIC Educational Resources Information Center

    Vander Wilt, Robert B.; Klocke, Ronald A.

    1971-01-01

    An alternative to the traditional orientation program was developed that forced students to consider their physical and psychological outer limits. Students were confronted in a new and unique way that contributed to the self actualization process of the female portion of the group. (Author/BY)

  10. Actual Leisure Participation of Norwegian Adolescents with Down Syndrome

    ERIC Educational Resources Information Center

    Dolva, Anne-Stine; Kleiven, Jo; Kollstad, Marit

    2014-01-01

    This article reports the actual participation in leisure activities by a sample of Norwegian adolescents with Down syndrome aged 14. Representing a first generation to grow up in a relatively inclusive context, they live with their families, attend mainstream schools, and are part of common community life. Leisure information was obtained in…

  11. Research into Students' Perceptions of Preferred and Actual Learning Environment.

    ERIC Educational Resources Information Center

    Hattie, John A.; And Others

    Measures of both preferred and actual classroom and school environment were administered to 1,675 secondary school students in New South Wales (Australia). Shortened versions of the My Class Inventory, Classroom Environment Scale, and Individualized Classroom Environment Questionnaire, as well as the Quality of School Life questionnaire were…

  12. MLCMS Actual Use, Perceived Use, and Experiences of Use

    ERIC Educational Resources Information Center

    Asiimwe, Edgar Napoleon; Grönlund, Åke

    2015-01-01

    Mobile learning involves use of mobile devices to participate in learning activities. Most e-learning activities are available to participants through learning systems such as learning content management systems (LCMS). Due to certain challenges, LCMS are not equally accessible on all mobile devices. This study investigates actual use, perceived…

  13. 40 CFR 74.22 - Actual SO2 emissions rate.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ....6 for natural gas For other fuels, the combustion source must specify the SO2 emissions factor. (c... (CONTINUED) SULFUR DIOXIDE OPT-INS Allowance Calculations for Combustion Sources § 74.22 Actual SO2 emissions rate. (a) Data requirements. The designated representative of a combustion source shall submit...

  14. What Does the Force Concept Inventory Actually Measure?

    ERIC Educational Resources Information Center

    Huffman, Douglas; Heller, Patricia

    1995-01-01

    The Force Concept Inventory (FCI) is a 29-question, multiple-choice test designed to assess students' Newtonian and non-Newtonian conceptions of force. Presents an analysis of FCI results as one way to determine what the inventory actually measures. (LZ)

  15. Progressive Digressions: Home Schooling for Self-Actualization.

    ERIC Educational Resources Information Center

    Rivero, Lisa

    2002-01-01

    Maslow's (1971) theory of primary creativeness is used as the basis for a self-actualization model of education. Examples of how to use the model in creative homeschooling are provided. Key elements include digressive and immersion learning, self-directed learning, and the integration of work and play. Teaching suggestions are provided. (Contains…

  16. A Taxometric Analysis of Actual Internet Sports Gambling Behavior

    ERIC Educational Resources Information Center

    Braverman, Julia; LaBrie, Richard A.; Shaffer, Howard J.

    2011-01-01

    This article presents findings from the first taxometric study of actual gambling behavior to determine whether we can represent the characteristics of extreme gambling as qualitatively distinct (i.e., taxonic) or as a point along a dimension. We analyzed the bets made during a 24-month study period by the 4,595 most involved gamblers among a…

  17. Prediction of elbow joint contact mechanics in the multibody framework.

    PubMed

    Rahman, Munsur; Cil, Akin; Stylianou, Antonis P

    2016-03-01

    Computational multibody musculoskeletal models of the elbow joint that are capable of simultaneous and accurate predictions of muscle and ligament forces, along with cartilage contact mechanics can be immensely useful in clinical practice. As a step towards producing a musculoskeletal model that includes the interaction between cartilage and muscle loading, the goal of this study was to develop subject-specific multibody models of the elbow joint with discretized humerus cartilage representation interacting with the radius and ulna cartilages through deformable contacts. The contact parameters for the compliant contact law were derived using simplified elastic foundation contact theory. The models were then validated by placing the model in a virtual mechanical tester for flexion-extension motion similar to a cadaver experiment, and the resulting kinematics were compared. Two cadaveric upper limbs were used in this study. The humeral heads were subjected to axial motion in a mechanical tester and the resulting kinematics from three bones were recorded for model validation. The maximum RMS error between the predicted and measured kinematics during the complete testing cycle was 2.7mm medial-lateral translation and 9.7° varus-valgus rotation of radius relative to humerus (for elbow 2). After model validation, a lateral ulnar collateral ligament (LUCL) deficient condition was simulated and, contact pressures and kinematics were compared to the intact elbow model. A noticeable difference in kinematics, contact area, and contact pressure were observed for LUCL deficient condition. LUCL deficiency induced higher internal rotations for both the radius and ulna during flexion and an associated medial shift of the articular contact area. PMID:26832391

  18. SARS Patients and Their Close Contacts

    MedlinePlus

    ... Fact Sheet for SARS Patients and Their Close Contacts Format: Select one PDF [256 KB] Recommend on ... that are not now known. What does "close contact" mean? In the context of SARS, close contact ...

  19. Multimodal characterization of contact lenses

    NASA Astrophysics Data System (ADS)

    Marcus, Michael A.; Compertore, David; Gibson, Donald S.; Herbrand, Matthew E.; Ignatovich, Filipp V.

    2015-10-01

    A table top instrument has been designed, constructed and tested to characterize all of the primary optical and physical properties of contact lenses. Measured optical properties include base power, cylinder power, cylindrical axis, prism, refractive index and wavefront aberrations. Measured physical properties include center thickness, lens diameter and lens sagittal depth. The instrument combines a Shack-Hartmann wavefront sensor (SHWS), a machine vision sensor, and a low coherence light interferometer (LCI) all coaxially aligned into a single tabletop unit. The unit includes a cuvette, mounted in a translatable sample chamber for holding the contact lens under test, and it can be configured to measure wet or dry contact lenses. During operation, the vision sensor measures the diameter of the lens, and locates the center of the lens. The lens is then aligned for other measurements. The vision sensor can also measure various alignment marks on the lens, as well as identify any alpha numerical features, which can be used to associate the lens orientation with the measured aberrations. The LCI measures the center thickness, sagittal depth and index of refraction of the contact lens. The base radius of curvature is then calculated using these measured parameters. The SHWS measures the lenses prescription power, including spherical, cylinder, prism, and higher order wavefront aberrations. NIST traceable calibration artifacts are used to calibrate the SHWS, machine vision and LCI modalities. Repeatability measurements on a contact lens in a saline solution are presented.

  20. Marine Bioinspired Underwater Contact Adhesion.

    PubMed

    Clancy, Sean K; Sodano, Antonio; Cunningham, Dylan J; Huang, Sharon S; Zalicki, Piotr J; Shin, Seunghan; Ahn, B Kollbe

    2016-05-01

    Marine mussels and barnacles are sessile biofouling organisms that adhere to a number of surfaces in wet environments and maintain remarkably strong bonds. Previous synthetic approaches to mimic biological wet adhesive properties have focused mainly on the catechol moiety, present in mussel foot proteins (mfps), and especially rich in the interfacial mfps, for example, mfp-3 and -5, found at the interface between the mussel plaque and substrate. Barnacles, however, do not use Dopa for their wet adhesion, but are instead rich in noncatecholic aromatic residues. Due to this anomaly, we were intrigued to study the initial contact adhesion properties of copolymerized acrylate films containing the key functionalities of barnacle cement proteins and interfacial mfps, for example, aromatic (catecholic or noncatecholic), cationic, anionic, and nonpolar residues. The initial wet contact adhesion of the copolymers was measured using a probe tack testing apparatus with a flat-punch contact geometry. The wet contact adhesion of an optimized, bioinspired copolymer film was ∼15.0 N/cm(2) in deionized water and ∼9.0 N/cm(2) in artificial seawater, up to 150 times greater than commercial pressure-sensitive adhesive (PSA) tapes (∼0.1 N/cm(2)). Furthermore, maximum wet contact adhesion was obtained at ∼pH 7, suggesting viability for biomedical applications. PMID:27046671

  1. Contact tracing and disease control.

    PubMed Central

    Eames, Ken T D; Keeling, Matt J

    2003-01-01

    Contact tracing, followed by treatment or isolation, is a key control measure in the battle against infectious diseases. It is an extreme form of locally targeted control, and as such has the potential to be highly efficient when dealing with low numbers of cases. For this reason it is frequently used to combat sexually transmitted diseases and new invading pathogens. Accurate modelling of contact tracing requires explicit information about the disease-transmission pathways from each individual, and hence the network of contacts. Here, pairwise-approximation methods and full stochastic simulations are used to investigate the utility of contact tracing. A simple relationship is found between the efficiency of contact tracing necessary for eradication and the basic reproductive ratio of the disease. This holds for a wide variety of realistic situations including heterogeneous networks containing core-groups or super-spreaders, and asymptomatic individuals. Clustering (transitivity) within the transmission network is found to destroy the relationship, requiring lower efficiency than predicted. PMID:14728778

  2. Contact electrification of insulating materials

    NASA Astrophysics Data System (ADS)

    Lacks, Daniel J.; Mohan Sankaran, R.

    2011-11-01

    The electrostatic charge that is generated when two materials are contacted or rubbed and then separated is a well-known physical process that has been studied for more than 2500 years. Contact electrification occurs in many contexts, both natural and technological. For example, in dust storms the collisions between particles lead to electrostatic charging and in extreme cases, extraordinary lightning displays. In electrophotography, toner particles are intentionally charged to guide their deposition in well-defined patterns. Despite such a long history and so many important consequences, a fundamental understanding of the mechanism behind contact electrification remains elusive. An open question is what type of species are transferred between the surfaces to generate charge—experiments suggest various species ranging from electrons to ions to nanoscopic bits of material, and theoretical work suggests that non-equilibrium states may play an important role. Another open question is the contact electrification that occurs when two insulating materials with identical physical properties touch—since there is no apparent driving force, it is not clear why charge transfer occurs. A third open question involves granular systems—models and experiments have shown that a particle-size dependence for the charging often exists. In this review, we discuss the fundamental aspects of contact electrification and highlight recent research efforts aimed at understanding these open questions.

  3. Apparent-contact-angle model at partial wetting and evaporation: impact of surface forces.

    PubMed

    Janeček, V; Nikolayev, V S

    2013-01-01

    This theoretical and numerical study deals with evaporation of a fluid wedge in contact with its pure vapor. The model describes a regime where the continuous wetting film is absent and the actual line of the triple gas-liquid-solid contact appears. A constant temperature higher than the saturation temperature is imposed at the solid substrate. The fluid flow is solved in the lubrication approximation. The introduction of the surface forces in the case of the partial wetting is discussed. The apparent contact angle (the gas-liquid interface slope far from the contact line) is studied numerically as a function of the substrate superheating, contact line velocity, and parameters related to the solid-fluid interaction (Young and microscopic contact angles, Hamaker constant, etc.). The dependence of the apparent contact angle on the substrate temperature is in agreement with existing approaches. For water, the apparent contact angle may be 20° larger than the Young contact angle for 1 K superheating. The effect of the surface forces on the apparent contact angle is found to be weak. PMID:23410341

  4. Apparent-contact-angle model at partial wetting and evaporation: Impact of surface forces

    NASA Astrophysics Data System (ADS)

    Janeček, V.; Nikolayev, V. S.

    2013-01-01

    This theoretical and numerical study deals with evaporation of a fluid wedge in contact with its pure vapor. The model describes a regime where the continuous wetting film is absent and the actual line of the triple gas-liquid-solid contact appears. A constant temperature higher than the saturation temperature is imposed at the solid substrate. The fluid flow is solved in the lubrication approximation. The introduction of the surface forces in the case of the partial wetting is discussed. The apparent contact angle (the gas-liquid interface slope far from the contact line) is studied numerically as a function of the substrate superheating, contact line velocity, and parameters related to the solid-fluid interaction (Young and microscopic contact angles, Hamaker constant, etc.). The dependence of the apparent contact angle on the substrate temperature is in agreement with existing approaches. For water, the apparent contact angle may be 20∘ larger than the Young contact angle for 1 K superheating. The effect of the surface forces on the apparent contact angle is found to be weak.

  5. A Direct analysis of elastic contact using super elements

    NASA Astrophysics Data System (ADS)

    Pedersen, Pauli

    2006-02-01

    Solutions to contact problems are important in mechanical as well as in civil engineering, and even for the most simple problems there is still a need for research results. In the present paper we suggest an alternative finite element procedure and by examples show the need for more knowledge related to the compliance of contact surfaces. The most simple solutions are named Hertz solutions from 1882, and we use some of these solutions for comparison with our finite element results. As a function of the total contact force we find the size of the contact area, the distribution of the contact pressure, and the contact compliance. In models of finite size the compliance depends on the flexibility of the total model, including the boundary condition of the model, and therefore disagreement with the locally based analytical models is expected and found. With computational contact mechanics we can solve more advanced contact problems and treat models that are closer to physical reality. The finite element method is widely used and solutions are obtained by incrementation and/or iteration for these non-linear problems with unknown boundary conditions. Still with these advanced tools the solution is difficult because of extreme sensitivity. Here we present a direct analysis of elastic contact without incrementation and iteration, and the procedure is based on a finite element super element technique. This means that the contacting bodies can be analyzed independently, and are only coupled through a direct analysis with low order super element stiffness matrices. The examples of the present paper are restricted to axisymmetric problems with isotropic, elastic materials and excluding friction. Direct extensions to cases of non-isotropy, including laminates, and to plane and general 3D models are possible.

  6. ESTIMATING WITHIN-SCHOOL CONTACT NETWORKS TO UNDERSTAND INFLUENZA TRANSMISSION

    PubMed Central

    Potter, Gail E.; Handcock, Mark S.; Longini, Ira M.; Halloran, M. Elizabeth

    2012-01-01

    Many epidemic models approximate social contact behavior by assuming random mixing within mixing groups (e.g., homes, schools, and workplaces). The effect of more realistic social network structure on estimates of epidemic parameters is an open area of exploration. We develop a detailed statistical model to estimate the social contact network within a high school using friendship network data and a survey of contact behavior. Our contact network model includes classroom structure, longer durations of contacts to friends than non-friends and more frequent contacts with friends, based on reports in the contact survey. We performed simulation studies to explore which network structures are relevant to influenza transmission. These studies yield two key findings. First, we found that the friendship network structure important to the transmission process can be adequately represented by a dyad-independent exponential random graph model (ERGM). This means that individual-level sampled data is sufficient to characterize the entire friendship network. Second, we found that contact behavior was adequately represented by a static rather than dynamic contact network. We then compare a targeted antiviral prophylaxis intervention strategy and a grade closure intervention strategy under random mixing and network-based mixing. We find that random mixing overestimates the effect of targeted antiviral prophylaxis on the probability of an epidemic when the probability of transmission in 10 minutes of contact is less than 0.004 and underestimates it when this transmission probability is greater than 0.004. We found the same pattern for the final size of an epidemic, with a threshold transmission probability of 0.005. We also find random mixing overestimates the effect of a grade closure intervention on the probability of an epidemic and final size for all transmission probabilities. Our findings have implications for policy recommendations based on models assuming random mixing, and

  7. 78 FR 14549 - National Contact Center; Information Collection; National Contact Center Customer Evaluation Survey

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... ADMINISTRATION National Contact Center; Information Collection; National Contact Center Customer Evaluation Survey AGENCY: Contact Center Services, Federal Citizen Information Center, Office of Citizen Services... requirement regarding the National Contact Center customer evaluation surveys. In this request, the...

  8. Variance and Covariance of Actual Relationships between Relatives at One Locus

    PubMed Central

    Garcia-Cortes, Luis Alberto; Legarra, Andres; Chevalet, Claude; Toro, Miguel Angel

    2013-01-01

    The relationship between pairs of individuals is an important topic in many areas of population and quantitative genetics. It is usually measured as the proportion of thegenome identical by descent shared by the pair and it can be inferred from pedigree information. But there is a variance in actual relationships as a consequence of Mendelian sampling, whose general formula has not been developed. The goal of this work is to develop this general formula for the one-locus situation,. We provide simple expressions for the variances and covariances of all actual relationships in an arbitrary complex pedigree. The proposed method relies on the use of the nine identity coefficients and the generalized relationship coefficients; formulas have been checked by computer simulation. Finally two examples for a short pedigree of dogs and a long pedigree of sheep are given. PMID:23451134

  9. Examples of simply-connected K-contact non-Sasakian manifolds of dimension 5

    NASA Astrophysics Data System (ADS)

    Kim, Jin Hong

    2015-12-01

    The existence of compact simply-connected K-contact, but not Sasakian, manifolds has been unknown only for dimension 5. The aim of this paper is to show that the Kollár's simply-connected example which is a Seifert bundle over the complex projective space ℂℙ2 and does not carry any Sasakian structure is actually a K-contact manifold. As a consequence, we affirmatively answer the above existence problem in dimension 5, establishing that there are infinitely many compact simply-connected K-contact manifolds of dimension 5 which do not carry a Sasakian structure.

  10. Preparation and Performance of Cu-Cr Contact Materials for Vacuum Switches with Low Contact Pressure

    NASA Astrophysics Data System (ADS)

    Chang, Yanli; Zheng, Wei; Zhou, Zhiming; Zhai, Yuxiang; Wang, Yaping

    2016-07-01

    Insufficient anti-welding properties limit the application of Cu-Cr contact material in vacuum switches with low contact pressure. The CuCr-W-C alloys that are prepared are for decreasing welding tendencies and keeping the voltage withstand by addition of W and C elements. It is found that the average welding force of CuCr-W-C alloys is reduced more than 50% compared with that of the Cu50 Cr50 alloy. Especially for CuCrW3.0C0.3 and CuCrW1.0C0.5, the welding forces reduce to only 10% of Cu50Cr50. Arc erosion areas of CuCr-W-C alloys are enlarged by five times more than that of the Cu50Cr50 alloy in the same arcing conditions. The results of type tests were qualified. The results suggested that the CuCrW2.0C1.0 alloy could be used in vacuum switches with low contact pressure to replace the W-Cu type contacts.

  11. Dermatitis, contact on the cheek (image)

    MedlinePlus

    ... skin inflammation (dermatitis) on the cheek caused by contact with a substance that produced an allergic reaction (allergen). Contact dermatitis causes redness, itching, and small blisters (vesicles).

  12. Contacts de langues et representations (Language Contacts and Representations).

    ERIC Educational Resources Information Center

    Matthey, Marinette, Ed.

    1997-01-01

    Essays on language contact and the image of language, entirely in French, include: "Representations 'du' contexte et representations 'en' contexte? Eleves et enseignants face a l'apprentissage de la langue" ("Representations 'of' Context or Representations 'in' Context? Students and Teachers Facing Language Learning" (Laurent Gajo); "Le crepuscule…

  13. Investigation of Nitride Morphology After Self-Aligned Contact Etch

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Keil, J.; Helmer, B. A.; Chien, T.; Gopaladasu, P.; Kim, J.; Shon, J.; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Self-Aligned Contact (SAC) etch has emerged as a key enabling technology for the fabrication of very large-scale memory devices. However, this is also a very challenging technology to implement from an etch viewpoint. The issues that arise range from poor oxide etch selectivity to nitride to problems with post etch nitride surface morphology. Unfortunately, the mechanisms that drive nitride loss and surface behavior remain poorly understood. Using a simple langmuir site balance model, SAC nitride etch simulations have been performed and compared to actual etched results. This approach permits the study of various etch mechanisms that may play a role in determining nitride loss and surface morphology. Particle trajectories and fluxes are computed using Monte-Carlo techniques and initial data obtained from double Langmuir probe measurements. Etched surface advancement is implemented using a shock tracking algorithm. Sticking coefficients and etch yields are adjusted to obtain the best agreement between actual etched results and simulated profiles.

  14. Nanotechnology and Food Contact Materials

    NASA Astrophysics Data System (ADS)

    Papaspyrides, Constantine (Costas) D.

    2010-06-01

    The use of nanotechnology in food contact materials is highlighted in relation to novel applications and potential implications for consumer safety and regulatory controls. Nanotechnology applications are expected to bring a range of benefits to the food sector, including improved packaging, antimicrobial properties, traceability and security of food products. The toxicological nature of hazard, likelihood of exposure and risk to consumers from nanotechnology-derived food/food packaging are largely unknown and this work highlights the benefits of nanotechnology in food contact materials but also the gaps in knowledge regarding consumers safety that require further research.

  15. Contact potential measurement: The preamplifier

    NASA Astrophysics Data System (ADS)

    Rossi, Frank

    1992-07-01

    The factors governing the choice of preamplifier type for the vibrating capacitive probe used in contact potential measurements are examined. Two types are compared: a high input impedance voltage amplifier and a current amplifier. The latter has been increasingly used in recent years due to its great advantages in dealing with parasitic input capacitance. We extend previous analyses, elucidating other advantages of the current amplifier. Particularly important are (i) the reduction of spurious microphonic signals, implying lower systematic error, and (ii) the white noise spectrum of its equivalent contact potential noise, which allows random error to be effectively reduced by increased averaging periods.

  16. Non- contacting capacitive diagnostic device

    DOEpatents

    Ellison, Timothy

    2005-07-12

    A non-contacting capacitive diagnostic device includes a pulsed light source for producing an electric field in a semiconductor or photovoltaic device or material to be evaluated and a circuit responsive to the electric field. The circuit is not in physical contact with the device or material being evaluated and produces an electrical signal characteristic of the electric field produced in the device or material. The diagnostic device permits quality control and evaluation of semiconductor or photovoltaic device properties in continuous manufacturing processes.

  17. [Tefillin-related contact dermatitis].

    PubMed

    Hashkes, Philip J; Sagi, Efraim

    2011-09-01

    We describe a 14 year-old male with a background of atopic dermatitis who developed a contact dermatitis reaction on the left arm to the leather straps of tefillin (phylacteries), a religious article worn by observant Jewish men from the age 13 years during most morning prayer services. Patch testing revealed contact allergy to potassium dichromate, a chemical involved in leather tanning. Placing the leather straps over clothing and later switching to potassium dichromate-free leather straps resolved the condition. It is important to recognize this uncommon phenomena in a population in which a large proportion regularly use this religious article. PMID:22026052

  18. Contacts of space--times

    SciTech Connect

    Maia, M.D.

    1981-03-01

    The concept of contact between manifolds is applied to space--times of general relativity. For a given background space--time a contact approximation of second order is defined and interpreted both from the point of view of a metric pertubation and of a higher order tangent manifold. In the first case, an application to the high frequency gravitational wave hypothesis is suggested. In the second case, a constant curvature tangent bundle is constructed and suggested as a means to define a ten parameter local space--time symmetry.

  19. Corneal topography and contact lenses.

    PubMed

    Szczotka, Loretta B

    2003-09-01

    Regardless of whether CVK is used qualitatively for RGP lens design selection or quantitatively in RGP parameter selection, it has a significant role in contact lens practice. Further advancements and testing on CVK-based RGP fitting modules and fluorescein simulations will make CVK an invaluable tool for the RGP lens fitter. Soft lens applications of CVK data are already being tested [42,43]. This technology will become the standard of care for all contact lens patients and will most likely replace the keratometer. PMID:14564765

  20. Contact allergy and depigmentation from alstroemeria.

    PubMed

    Björkner, B E

    1982-05-01

    Alstroemeria plants have increased in popularity in recent years, but surprisingly few cases of contact allergy have been reported. Observations of combined sensitivity between Alstroemeria and Tulipa have given support to the assumption that they contain identical sensitizing agents. A patient working as a gardner developed a dermatitis from Alstroemeria. Patch tests with Alstroemeria were positive, but patch tests with Tulipa were negative. 2 months after test application, the patient showed depigmented areas at the test sites and at the sites of a previous dermatitis. The depigmented test areas remained unchanged at least a year after test application. Whether the depigmentation was due to some unique character of the molecular structure of the unknown Alstroemeria allergen, or to a unique biological characteristic of the patient, remains to be determined. PMID:6212185

  1. Contact and friction of nanoasperities: effects of adsorbed monolayers.

    PubMed

    Cheng, Shengfeng; Luan, Binquan; Robbins, Mark O

    2010-01-01

    Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, and spherical tip with radius of order 30 nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare surfaces showed that the atomic scale deviations from a sphere that are present on any tip constructed from discrete atoms lead to significant deviations from continuum theory and dramatic variability in friction forces. Introducing an adsorbed monolayer leads to larger deviations from continuum theory but decreases the variations between tips with different atomic structure. Although the film is fluid, it remains in the contact and behaves qualitatively like a thin elastic coating except for certain tips at high loads. Measures of the contact area based on the moments or outer limits of the pressure distribution and on counting contacting atoms are compared. The number of tip atoms making contact during a time interval Deltat grows as a power of Deltat when the film is present and as the logarithm of Deltat for bare surfaces. Friction is measured by displacing the tip at a constant velocity or pulling the tip with a spring. Both static and kinetic friction rise linearly with load at small loads. Transitions in the state of the film lead to nonlinear behavior at large loads. The friction is less clearly correlated with contact area than load. PMID:20365427

  2. Solving conformal wheel-rail rolling contact problems

    NASA Astrophysics Data System (ADS)

    Vollebregt, Edwin; Segal, Guus

    2014-05-01

    The stresses between railway wheels and rails can be computed using different types of contact models: simplified methods, half-space-based boundary element approaches and finite element models. For conformal contact situations, particularly the contact between flange root and rail gauge corner, none of these models work satisfactorily. Finite element methods are too slow, half-space approaches ignore the effects of conformality, and simplified approaches schematise the elasticity of the material even further. This paper presents a thorough investigation of the conformal wheel-rail rolling contact problem. We use CONTACT's boundary element approach together with numerical influence coefficients, that are computed using the finite element approach. The resulting method is fast and detailed and can be embedded into vehicle system dynamics simulation. The results indicate that the contact area is longer and narrower, with smaller area and reduced stiffness, than is predicted by the half-space approach. The predicted maximum pressures are increased by 30%. Finally the longitudinal and lateral forces changed up to 15% of the Coulomb maximum.

  3. Morphology and the Strength of Intermolecular Contact in Protein Crystals

    NASA Technical Reports Server (NTRS)

    Matsuura, Yoshiki; Chernov, Alexander A.

    2002-01-01

    The strengths of intermolecular contacts (macrobonds) in four lysozyme crystals were estimated based on the strengths of individual intermolecular interatomic interaction pairs. The periodic bond chain of these macrobonds accounts for the morphology of protein crystals as shown previously. Further in this paper, the surface area of contact, polar coordinate representation of contact site, Coulombic contribution on the macrobond strength, and the surface energy of the crystal have been evaluated. Comparing location of intermolecular contacts in different polymorphic crystal modifications, we show that these contacts can form a wide variety of patches on the molecular surface. The patches are located practically everywhere on this surface except for the concave active site. The contacts frequently include water molecules, with specific intermolecular hydrogen-bonds on the background of non-specific attractive interactions. The strengths of macrobonds are also compared to those of other protein complex systems. Making use of the contact strengths and taking into account bond hydration we also estimated crystal-water interfacial energies for different crystal faces.

  4. A generative model for protein contact networks.

    PubMed

    Livi, Lorenzo; Maiorino, Enrico; Giuliani, Alessandro; Rizzi, Antonello; Sadeghian, Alireza

    2016-07-01

    In this paper, we present a generative model for protein contact networks (PCNs). The soundness of the proposed model is investigated by focusing primarily on mesoscopic properties elaborated from the spectra of the graph Laplacian. To complement the analysis, we also study the classical topological descriptors, such as statistics of the shortest paths and the important feature of modularity. Our experiments show that the proposed model results in a considerable improvement with respect to two suitably chosen generative mechanisms, mimicking with better approximation real PCNs in terms of diffusion properties elaborated from the normalized Laplacian spectra. However, as well as the other network models, it does not reproduce with sufficient accuracy the shortest paths structure. To compensate this drawback, we designed a second step involving a targeted edge reconfiguration process. The ensemble of reconfigured networks denotes further improvements that are statistically significant. As an important byproduct of our study, we demonstrate that modularity, a well-known property of proteins, does not entirely explain the actual network architecture characterizing PCNs. In fact, we conclude that modularity, intended as a quantification of an underlying community structure, should be considered as an emergent property of the structural organization of proteins. Interestingly, such a property is suitably optimized in PCNs together with the feature of path efficiency. PMID:26474097

  5. MoS2-Titanium Contact Interface Reactions.

    PubMed

    McDonnell, Stephen; Smyth, Christopher; Hinkle, Christopher L; Wallace, Robert M

    2016-03-01

    The formation of the Ti-MoS2 interface, which is heavily utilized in nanoelectronic device research, is studied by X-ray photoelectron spectroscopy. It is found that, if deposition under high vacuum (∼1 × 10(-6) mbar) as opposed to ultrahigh vacuum (∼1 × 10(-9) mbar) conditions are used, TiO2 forms at the interface rather than Ti. The high vacuum deposition results in an interface free of any detectable reaction between the semiconductor and the deposited contact. In contrast, when metallic titanium is successfully deposited by carrying out depositions in ultrahigh vacuum, the titanium reacts with MoS2 forming Ti(x)S(y) and metallic Mo at the interface. These results have far reaching implications as many prior studies assuming Ti contacts may have actually used TiO2 due to the nature of the deposition tools used. PMID:26967016

  6. Thermal and electrical contact conductance studies

    NASA Technical Reports Server (NTRS)

    Vansciver, S. W.; Nilles, M.

    1985-01-01

    Prediction of electrical and thermal contact resistance for pressed, nominally flat contacts is complicated by the large number of variables which influence contact formation. This is reflected in experimental results as a wide variation in contact resistances, spanning up to six orders of magnitude. A series of experiments were performed to observe the effects of oxidation and surface roughness on contact resistance. Electrical contact resistance and thermal contact conductance from 4 to 290 K on OFHC Cu contacts are reported. Electrical contact resistance was measured with a 4-wire DC technique. Thermal contact conductance was determined by steady-state longitudinal heat flow. Corrections for the bulk contribution ot the overall measured resistance were made, with the remaining resistance due solely to the presence of the contact.

  7. Advances in contact algorithms and their application to tires

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Tanner, John A.

    1988-01-01

    Currently used techniques for tire contact analysis are reviewed. Discussion focuses on the different techniques used in modeling frictional forces and the treatment of contact conditions. A status report is presented on a new computational strategy for the modeling and analysis of tires, including the solution of the contact problem. The key elements of the proposed strategy are: (1) use of semianalytic mixed finite elements in which the shell variables are represented by Fourier series in the circumferential direction and piecewise polynomials in the meridional direction; (2) use of perturbed Lagrangian formulation for the determination of the contact area and pressure; and (3) application of multilevel iterative procedures and reduction techniques to generate the response of the tire. Numerical results are presented to demonstrate the effectiveness of a proposed procedure for generating the tire response associated with different Fourier harmonics.

  8. Children’s Contact With Their Incarcerated Parents

    PubMed Central

    Poehlmann, Julie; Dallaire, Danielle; Loper, Ann Booker; Shear, Leslie D.

    2014-01-01

    Approximately 1.7 million children have parents who are incarcerated in prison in the United States, and possibly millions of additional children have a parent incarcerated in jail. Many affected children experience increased risk for developing behavior problems, academic failure, and substance abuse. For a growing number of children, incarcerated parents, caregivers, and professionals, parent– child contact during the imprisonment period is a key issue. In this article, we present a conceptual model to provide a framework within which to interpret findings about parent– child contact when parents are incarcerated. We then summarize recent research examining parent–child contact in context. On the basis of the research reviewed, we present initial recommendations for children’s contact with incarcerated parents and also suggest areas for future intervention and research with this vulnerable population. PMID:20822198

  9. Actual curriculum development practices instrument: Testing for factorial validity

    NASA Astrophysics Data System (ADS)

    Foi, Liew Yon; Bakar, Kamariah Abu; Hamzah, Mohd Sahandri Gani; Alwi, Nor Hayati

    2014-09-01

    The Actual Curriculum Development Practices Instrument (ACDP-I) was developed and the factorial validity of the ACDP-I was tested (n = 107) using exploratory factor analysis procedures in the earlier work of [1]. Despite the ACDP-I appears to be content and construct valid instrument with very high internal reliability qualities for using in Malaysia, the accumulated evidences are still needed to provide a sound scientific basis for the proposed score interpretations. Therefore, the present study addresses this concern by utilising the confirmatory factor analysis to further confirm the theoretical structure of the variable Actual Curriculum Development Practices (ACDP) and enrich the psychometrical properties of ACDP-I. Results of this study have practical implication to both researchers and educators whose concerns focus on teachers' classroom practices and the instrument development and validation process.

  10. DISEASES CAUSED BY WATER CONTACT

    EPA Science Inventory

    Diseases associated with water contact are reviewed with respect to the sources of etiological agents, the types of diseases and the conditions under which they occur. The sources of disease agents fall into three general groups; point sources such as sewage treatment plants; dis...

  11. Contact symmetries and Hamiltonian thermodynamics

    SciTech Connect

    Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.

    2015-10-15

    It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production.

  12. Non-contact ECG monitoring

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexey S.; Erlikh, Vadim V.; Kodkin, Vladimir L.; Keller, Andrei V.; Epishev, Vitaly V.

    2016-03-01

    The research is dedicated to non-contact methods of electrocardiography. The authors describe the routine of experimental procedure and suggest the approach to solving the problems which arise at indirect signal recording. The paper presents the results of experiments conducted by the authors, covers the flow charts of ECG recorders and reviews the drawbacks of filtering methods used in foreign equivalents.

  13. Barrier/Cu contact resistivity

    SciTech Connect

    Reid, J.S.; Nicolet, M.A.; Angyal, M.S.; Lilienfeld, D.; Shacham-Diamand, Y.; Smith, P.M.

    1995-10-17

    The specific contact resistivity of Cu with ({alpha} + {beta})-Ta, TiN, {alpha}-W, and amorphous-Ta{sub 36}Si{sub 14}N{sub 50} barrier films is measured using a novel four-point-probe approach. Geometrically, the test structures consist of colinear sets of W-plugs to act as current and voltage probes that contact the bottom of a planar Cu/barrier/Cu stack. Underlying Al interconnects link the plugs to the current source and voltmeter. The center-to-center distance of the probes ranges from 3 to 200 {micro}m. Using a relation developed by Vu et al., a contact resistivity of roughly 7 {times} 10{sup {minus}9} {Omega} cm{sup 2} is obtained for all tested barrier/Cu combinations. By reflective-mode small-angle X-ray scattering, the similarity in contact resistivity among the barrier films may be related to interfacial impurities absorbed from the deposition process.

  14. Cultural Contacts, Attitudes and Understanding.

    ERIC Educational Resources Information Center

    Reich, Carol; Purbhoo, Mary

    To investigate the effects of contacts with people from other cultures, students in nine Canadian secondary schools with differing ethnic population densities were compared. The first focus of the study was the development of cross-cultural understanding. Three measurement instruments were administered to eleventh grade English and history classes…

  15. Patterns of Nonresident Father Contact

    PubMed Central

    CHEADLE, JACOB E.; AMATO, PAUL R.; KING, VALARIE

    2010-01-01

    We used the National Longitudinal Survey of Youth 1979 cohort (NLSY79) from 1979 to 2002 and the Children of the National Longitudinal Survey of Youth (CNLSY) from 1986 to 2002 to describe the number, shape, and population frequencies of U.S. nonresident father contact trajectories over a 14-year period using growth mixture models. The resulting four-category classification indicated that nonresident father involvement is not adequately characterized by a single population with a monotonic pattern of declining contact over time. Contrary to expectations, about two-thirds of fathers were consistently either highly involved or rarely involved in their children’s lives. Only one group, constituting approximately 23% of fathers, exhibited a clear pattern of declining contact. In addition, a small group of fathers (8%) displayed a pattern of increasing contact. A variety of variables differentiated between these groups, including the child’s age at father-child separation, whether the child was born within marriage, the mother’s education, the mother’s age at birth, whether the father pays child support regularly, and the geographical distance between fathers and children. PMID:20355691

  16. Electrical contact tool set station

    DOEpatents

    Byers, M.E.

    1988-02-22

    An apparatus is provided for the precise setting to zero of electrically conductive cutting tools used in the machining of work pieces. An electrically conductive cylindrical pin, tapered at one end to a small flat, rests in a vee-shaped channel in a base so that its longitudinal axis is parallel to the longitudinal axis of the machine's spindle. Electronic apparatus is connected between the cylindrical pin and the electrically conductive cutting tool to produce a detectable signal when contact between tool and pin is made. The axes of the machine are set to zero by contact between the cutting tool and the sides, end or top of the cylindrical pin. Upon contact, an electrical circuit is completed, and the detectable signal is produced. The tool can then be set to zero for that axis. Should the tool contact the cylindrical pin with too much force, the cylindrical pin would be harmlessly dislodged from the vee-shaped channel, preventing damage either to the cutting tool or the cylindrical pin. 5 figs.

  17. Contact lens related corneal ulcer.

    PubMed

    Loh, Ky; Agarwal, P

    2010-01-01

    A corneal ulcer caused by infection is one of the major causes of blindness worldwide. One of the recent health concerns is the increasing incidence of corneal ulcers associated with contact lens user especially if the users fail to follow specific instruction in using their contact lenses. Risk factors associated with increased risk of contact lens related corneal ulcers are: overnight wear, long duration of continuous wear, lower socio-economic classes, smoking, dry eye and poor hygiene. The presenting symptoms of contact lens related corneal ulcers include eye discomfort, foreign body sensation and lacrimation. More serious symptoms are redness (especially circum-corneal injection), severe pain, photophobia, eye discharge and blurring of vision. The diagnosis is established by a thorough slit lamp microscopic examination with fluorescein staining and corneal scraping for Gram stain and culture of the infective organism. Delay in diagnosing and treatment can cause permanent blindness, therefore an early referral to ophthalmologist and commencing of antimicrobial therapy can prevent visual loss. PMID:25606178

  18. Assessing Measures of Contact Theory.

    ERIC Educational Resources Information Center

    Brown, William R.; Patchen, Martin

    This paper consolidates findings from two related studies: William Brown's research on the predictive ability of measures of early and non-high school interracial contact/opportunities that appear to affect interracial attitudes and behaviors in high school; and Martin Patchen's investigation in Indianapolis, Indiana high schools analyzing the…

  19. Patient Compliance During Contact Lens Wear: Perceptions, Awareness, and Behavior

    PubMed Central

    Bui, Thai H.; Cavanagh, H. Dwight; Robertson, Danielle M.

    2011-01-01

    Objectives Patient noncompliance with recommended hygienic practices in contact lens wear is often considered a significant risk factor for microbial keratitis and adverse contact lens–related events. Despite advancements in lens materials and care solutions, noncompliant behavior continues to hinder efforts to maximize contact lens safety. The objective of this pilot study was to assess the relationship between perceived and actual compliance with awareness of risk and behavior. Methods One hundred sixty-two established contact lens wearers were sequentially evaluated after their routine contact lens examination at the Optometry Clinic at the University of Texas Southwestern Medical Center at Dallas, TX. Each patient was questioned by a single trained interviewer regarding his or her lens care practices and knowledge of risk factors associated with lens wear. Results Eighty-six percent of patients believed they were compliant with lens wear and care practices; 14% identified themselves as noncompliant. Using a scoring model, 32% demonstrated good compliance, 44% exhibited average compliance, and 24% were noncompliant; age was a significant factor (P = 0.020). Only 34% of patients who perceived themselves as compliant exhibited a good level of compliance (P<0.001). Eighty percent of patients reported an awareness of risk factors, but awareness did not influence negative behavior. Replacing the lens case was the only behavior associated with a positive history for having experienced a prior contact lens–related complication (P = 0.002). Conclusions Perceived compliance is not an indicator for appropriate patient behavior. A large proportion of patients remain noncompliant despite awareness of risk. Education alone is not a sufficient strategy to improve behavior; newer approaches aimed at improving compliance with lens care practices are urgently needed. PMID:20935569

  20. FRACTIONAL CRYSTALLIZATION FLOWSHEET TESTS WITH ACTUAL TANK WASTE

    SciTech Connect

    HERTING, D.L.

    2006-10-18

    Laboratory-scale flowsheet tests of the fractional crystallization process were conducted with actual tank waste samples in a hot cell at the 222-S Laboratory. The process is designed to separate medium-curie liquid waste into a low-curie stream for feeding to supplemental treatment and a high-curie stream for double-shell tank storage. Separations criteria (for Cs-137 sulfate, and sodium) were exceeded in all three of the flowsheet tests that were performed.

  1. FRACTIONAL CRYSTALLIZATION FLOWSHEET TESTS WITH ACTUAL TANK WASTE

    SciTech Connect

    HERTING, D.L.

    2007-04-13

    Laboratory-scale flowsheet tests of the fractional crystallization process were conducted with actual tank waste samples in a hot cell at the 2224 Laboratory. The process is designed to separate medium-curie liquid waste into a low-curie stream for feeding to supplemental treatment and a high-curie stream for double-shell tank storage. Separations criteria (for Cesium-137 sulfate and sodium) were exceeded in all three of the flowsheet tests that were performed.

  2. 63. VIEW OF AUTOTRANSFERS. THE ACTUAL AUTOTRANSFERS ARE ENCLOSED IN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. VIEW OF AUTOTRANSFERS. THE ACTUAL AUTOTRANSFERS ARE ENCLOSED IN THE OIL FILLED CYLINDERS ON THE RIGHT OF THE PHOTOGRAPH. THESE ELECTRICAL DEVICES BOOSTED THE GENERATOR OUTPUT OF 11,000 VOLTS TO 22,000 VOLTS PRIOR TO TRANSMISSION OUT TO THE MAIN FEEDER LINES. A SPARE INNER UNIT IS CONTAINED IN THE METAL BOX AT THE LEFT OF THE PHOTOGRAPH. - New York, New Haven & Hartford Railroad, Cos Cob Power Plant, Sound Shore Drive, Greenwich, Fairfield County, CT

  3. The actual citation impact of European oncological research.

    PubMed

    López-Illescas, Carmen; de Moya-Anegón, Félix; Moed, Henk F

    2008-01-01

    This study provides an overview of the research performance of major European countries in the field Oncology, the most important journals in which they published their research articles, and the most important academic institutions publishing them. The analysis was based on Thomson Scientific's Web of Science (WoS) and calculated bibliometric indicators of publication activity and actual citation impact. Studying the time period 2000-2006, it gives an update of earlier studies, but at the same time it expands their methodologies, using a broader definition of the field, calculating indicators of actual citation impact, and analysing new and policy relevant aspects. Findings suggest that the emergence of Asian countries in the field Oncology has displaced European articles more strongly than articles from the USA; that oncologists who have published their articles in important, more general journals or in journals covering other specialties, rather than in their own specialist journals, have generated a relatively high actual citation impact; and that universities from Germany, and--to a lesser extent--those from Italy, the Netherlands, UK, and Sweden, dominate a ranking of European universities based on number of articles in oncology. The outcomes illustrate that different bibliometric methodologies may lead to different outcomes, and that outcomes should be interpreted with care. PMID:18039565

  4. Two new three-dimensional contact algorithms for staggered Lagrangian Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Jia, Zupeng; Gong, Xiangfei; Zhang, Shudao; Liu, Jun

    2014-06-01

    This paper presents two new three-dimensional contact algorithms for staggered Lagrangian Hydrodynamics, named discrete accurate matching method and discrete Lagrangian multiplier method. These new contact algorithms utilize the unified contact algorithm for contact searching. Contact segments from all potential contact surfaces are treated as a single set. The basic idea of these new methods is to partition all contact segments into triangular facets firstly; then for each pair of two triangular facets which correspond to a hitting node and a target node respectively, these two triangular facets are projected to one plane and their intersection area is calculated; the nodal masses and nodal forces of the hitting node and the target node are distributed to the intersection portions of these two triangular facets respectively according to the proportion of the intersection area to corresponding nodal area. In the discrete accurate matching method, the masses and forces of the intersection portions of these two triangular facets are added to corresponding contact nodes of each other, and then the accelerations and velocities of the contact nodes are updated; while in the discrete Lagrangian multiplier method, the intersection portions of these two triangular facets are considered as a 1D contact pair in the normal direction for which the contact force is explicitly calculated by the Lagrangian multiplier method for a 1D contact pair of one hitting point and one target point, then the contact force being added to corresponding contact nodes. These new contact algorithms are assessed through several numerical tests performed on three-dimensional structured and unstructured meshes. The results of these tests show the accuracy and robustness of these new methods.

  5. Chronic, irritant contact dermatitis: Mechanisms, variables, and differentiation from other forms of contact dermatitis

    SciTech Connect

    Dahl, M.V. )

    1988-01-01

    Irritant dermatitis is an eczematous reaction to toxic chemicals contacting the skin. The mechanisms by which various chemicals elicit dermatitis are multiple. Strong irritants quickly elicit signs and symptoms of dermatitis, but weak irritants may not. Chronic cumulative exposure to weak irritants can elicit dermatitis which may mimic allergic contact dermatitis and mislead the physician and patient with respect to cause and preventative strategy. The skins of different people vary in susceptibilities to irritation. Susceptibility is also influenced by chemical properties, vehicles, concentrations, amounts applied to the skin surface, surface area, regional variations, length of exposure, method of exposure, age, sex, race, genetic background, environmental factors, hardening, concomitant disease, and the excited skin syndrome as well as treatment. Patch testing can help distinguish between allergens and irritants, but pitfalls may mislead.35 references.

  6. 41 CFR 301-11.6 - Where do I find maximum per diem and actual expense rates?

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., and available on the Internet at http://www.gsa.gov/perdiem. For actual expense, see 41 CFR 301-11.300... or Internet at http://www.defensetravel.dod.mil/site/perdiemCalc.cfm. (Rates also appear in section... State Standardized Regulations (Government Civilians-Foreign Areas) and available on the Internet at...

  7. The nature of electrical interaction of Schottky contacts

    SciTech Connect

    Torkhov, N. A.

    2011-08-15

    Electrical interaction between metal-semiconductor contacts combined in a diode matrix with a Schottky barrier manifests itself in an appreciable variation in their surface potentials and static current-volt-characteristics. The necessary condition for appearance of electrical interaction between such contacts consists in the presence of a peripheral electric field (a halo) around them; this field propagates to a fairly large distances (<30 {mu}m). The sufficient condition is the presence of regions where the above halos overlap. It has been shown that variation in the surface potential and the current-voltage characteristics of contacts occurs under the effect of the intrinsic electric field of the contact's periphery and also under the effect of an electric field at matrix periphery; the latter field is formed as a result of superposition of electric fields of halos which form its contacts. The degree of the corresponding effect is governed by the distance between contacts and by the total charge of the space charge regions for all contacts of the matrix: their number, sizes (diameter D{sub i,j}), concentration of doping impurities in the semiconductor N{sub D}, and physical nature of a metal-semiconductor system with a Schottky barrier (with the barrier height {phi}{sub b}). It is established that bringing the contacts closer leads to a relative decrease in the threshold value of the 'dead' zone in the forward current-voltage characteristics, an increase in the effective height of the barrier, and an insignificant increase in the nonideality factor. An increase in the total area of contacts (a total electric charge in the space charge region) in the matrix brings about an increase in the threshold value of the 'dead' zone, a relative decrease in the effective barrier height, and an insignificant increase in the ideality factor.

  8. Computing Contact Stresses In Gear Teeth

    NASA Technical Reports Server (NTRS)

    Oswald, Fred B.; Somprakit, Paisan; Huston, Ronald L.

    1995-01-01

    Improved method of computing contact stresses in gear teeth accounts for complicating effects like those of static and sliding friction. Provides iterative procedure for determination of contact region and nodal contact forces along with contact stresses. Method based on equations and computational procedure incorporating these effects routinely.

  9. A method for improved accuracy in three dimensions for determining wheel/rail contact points

    NASA Astrophysics Data System (ADS)

    Yang, Xinwen; Gu, Shaojie; Zhou, Shunhua; Zhou, Yu; Lian, Songliang

    2015-11-01

    Searching for the contact points between wheels and rails is important because these points represent the points of exerted contact forces. In order to obtain an accurate contact point and an in-depth description of the wheel/rail contact behaviours on a curved track or in a turnout, a method with improved accuracy in three dimensions is proposed to determine the contact points and the contact patches between the wheel and the rail when considering the effect of the yaw angle and the roll angle on the motion of the wheel set. The proposed method, with no need of the curve fitting of the wheel and rail profiles, can accurately, directly, and comprehensively determine the contact interface distances between the wheel and the rail. The range iteration algorithm is used to improve the computation efficiency and reduce the calculation required. The present computation method is applied for the analysis of the contact of rails of CHINA (CHN) 75 kg/m and wheel sets of wearing type tread of China's freight cars. In addition, it can be proved that the results of the proposed method are consistent with that of Kalker's program CONTACT, and the maximum deviation from the wheel/rail contact patch area of this two methods is approximately 5%. The proposed method, can also be used to investigate static wheel/rail contact. Some wheel/rail contact points and contact patch distributions are discussed and assessed, wheel and rail non-worn and worn profiles included.

  10. Contact discontinuity as a stabilizing factor in contact binary stars

    NASA Astrophysics Data System (ADS)

    Sarna, M. J.

    1991-01-01

    A mechanism is proposed, which can stabilize oscillation cycles, in the sense of the thermal relaxation oscillation theory, during the first phase of the contact configuration evolution. It is argued that a special structure of the secondary component (the inversion layer) acts as a stabilizing factor that is complementary to another stabilizing factor (evolved primary component) proposed by Rahunen (1981). The proposition explains quite well the fact that not many systems with EB and EW light curves are observed.

  11. ACTUAL WASTE TESTING OF GYCOLATE IMPACTS ON THE SRS TANK FARM

    SciTech Connect

    Martino, C.

    2014-05-28

    Glycolic acid is being studied as a replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste Tank Farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the Tank Farm were addressed via a literature review and simulant testing, but several outstanding issues remained. This report documents the actual-waste tests to determine the impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The objectives of this study are to address the following: Determine the extent to which sludge constituents (Pu, U, Fe, etc.) dissolve (the solubility of sludge constituents) in the glycolate-containing 2H-evaporator feed. Determine the impact of glycolate on the sorption of fissile (Pu, U, etc.) components onto sodium aluminosilicate solids. The first objective was accomplished through actual-waste testing using Tank 43H and 38H supernatant and Tank 51H sludge at Tank Farm storage conditions. The second objective was accomplished by contacting actual 2H-evaporator scale with the products from the testing for the first objective. There is no anticipated impact of up to 10 g/L of glycolate in DWPF recycle to the Tank Farm on tank waste component solubilities as investigated in this test. Most components were not influenced by glycolate during solubility tests, including major components such as aluminum, sodium, and most salt anions. There was potentially a slight increase in soluble iron with added glycolate, but the soluble iron concentration remained so low (on the order of 10 mg/L) as to not impact the iron to fissile ratio in sludge. Uranium and plutonium appear to have been supersaturated in 2H-evaporator feed solution mixture used for this testing. As a result, there was a reduction of soluble uranium and plutonium as a function of time. The change in soluble uranium concentration was

  12. [Emission Characteristics of Vehicle Exhaust in Beijing Based on Actual Traffic Flow Information].

    PubMed

    Fan, Shou-bin; Tian, Ling-di; Zhang, Dong-xu; Qu, Song

    2015-08-01

    The basic data of traffic volume, vehicle type constitute and speed on road networks in Beijing was obtained fly modei simulation and field survey. Based on actual traffic flow information and. emission factors data with temporal and spatial distribution features, emission inventory of motor vehicle exhaust in Beijing was built on the ArcGIS platform, meanwhile, the actual road emission characteristics and spatial distribution of the pollutant emissions were analyzed. The results showed that the proportion of passenger car was higher than 89% on each type of road in the urban, and the proportion of passenger car was the highest in suburban roads as well while the pickup truck, medium truck, heavy truck, motorbus, tractor and motorcycle also occupied a certain proportion. There was a positive correlation between the pollutant emission intensity and traffic volume, and the emission intensity was generally higher in daytime than nighttime, but the diurnal variation trend of PM emission was not clear for suburban roads and the emission intensity was higher in nighttime than daytime for highway. The emission intensities in urban area, south, southeast and northeast areas near urban were higher than those in the western and northern mountainous areas with lower density of road network. The ring roads in urban and highways in suburban had higher emission intensity because of the heavy traffic volume. PMID:26592000

  13. Spin analysis of concentrated traction contacts

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.

    1983-01-01

    Spin, the result of a mismatch in contact radii on either side of the point of rolling, has a detrimental effect on traction contact performance. It occurs in concentrated contacts having conical or contoured rolling elements, such as those in traction drives or angular contact bearings, and is responsible for an increase in contact heating and power loss. The kinematics of spin producing contact geometries and the subsequent effect on traction and power loss are investigated. The influence of lubricant traction characteristics and contact geometries that minimize spin are also addressed.

  14. Phenomena resulting from hypergolic contact

    NASA Astrophysics Data System (ADS)

    Forness, Jordan M.

    Understanding hypergolic ignition is critical for the safe and successful operation of hypergolic engines. The complex coupling of physical and chemical processes during hypergolic ignition complicates analysis of the event. Presently, hypergolic ignition models cannot simulate liquid contact and mixing or liquid-phase chemical reactions, and rely on experimental results for validation. In some cases, chemical kinetics of hypergolic propellants and fluid dynamics of droplet collisions couple to produce unexpected phenomena. This research investigates contact between droplets and pools of liquid hypergolic propellants under various conditions in order to investigate these liquid-phase reactions and categorize the resulting interaction. During this experiment, 142 drop tests were performed to investigate phenomena associated with hypergolic contact of various propellants. A drop of fuel impacted a semi-ellipsoidal pool of oxidizer at varying impact velocities and impact geometries. The temperature, pressure, ambient atmosphere, and propellant quality were all controlled during the experiment, as these factors have been shown to influence hypergolic ignition delay. Three distinct types of impacts were identified: explosions, bounces, and splashes. The impact type was found to depend on the impact Weber number and impact angle. Splashes occurred above a critical Weber number of 250, regardless of impact angle. Explosions occurred for Weber numbers less than 250, and for impact angles less than seven degrees. If the impact angle was greater than seven degrees then the test resulted in a bounce. Literature related to explosions induced by hypergolic contact was reviewed. Explosions were observed to occur inconsistently, a feature that has never been addressed. Literature related to non-reactive splashing, bouncing, and coalescence was reviewed for insight into the explosion phenomenon. I propose that the dependence of impact angle on the transition between explosion and

  15. Improved Electrical Contact For Dowhhole Drilling Networks

    DOEpatents

    Hall, David R.; Hall, Jr., H. Tracy; Pixton, David S.; Dahlgren, Scott; Fox, Joe; Sneddon, Cameron

    2005-08-16

    An electrical contact system for transmitting information across tool joints while minimizing signal reflections that occur at the tool joints includes a first electrical contact comprising an annular resilient material. An annular conductor is embedded within the annular resilient material and has a surface exposed from the annular resilient material. A second electrical contact is provided that is substantially equal to the first electrical contact. Likewise, the second electrical contact has an annular resilient material and an annular conductor. The two electrical contacts configured to contact one another such that the annular conductors of each come into physical contact. The annular resilient materials of each electrical contact each have dielectric characteristics and dimensions that are adjusted to provide desired impedance to the electrical contacts.

  16. Urban rail transit projects: Forecast versus actual ridership and costs. Final report

    SciTech Connect

    Pickrell, D.H.

    1989-10-01

    Substantial errors in forecasting ridership and costs for the ten rail transit projects reviewed in the report put forth the possibility that more accurate forecasts would have led decision-makers to select projects other than those reviewed. The study examines the accuracy of forecasts prepared for ten major capital improvement projects in nine urban areas during 1971-1987. Each project includes construction of a fixed transit guideway: Rapid Rail or Metrorail (Washington DC, Atlanta, Baltimore, Miami); Light Rail Transit (Buffalo, Pittsburgh, Portland, Sacramento); and Downtown Peoplemover (Miami and Detroit). The study examines why actual costs and ridership differed so markedly from their forecast values. It focuses on the accuracy of projections made available to local decision-makers at the time when the choice among alternative projects was actually made. The study compares forecast and actual values for four types of measures: ridership, capital costs and financing, operating and maintenance costs, and cost-effectiveness. The report is organized into 6 chapters, numerous tables, and an appendix that documents the sources of all data appearing in the tables presented in the report.

  17. Pseudoelastic deformation during nanoscale adhesive contact formation.

    PubMed

    Mordehai, Dan; Rabkin, Eugen; Srolovitz, David J

    2011-08-26

    Molecular dynamics simulations are employed to demonstrate that adhesive contact formation through classical jump to contact is mediated by extensive dislocation activity in metallic nanoparticles. The dislocations generated during jump to contact are completely annihilated by the completion of the adhesive contact, leaving the nanoparticles dislocation-free. This rapid and efficient jump to contact process is pseudoelastic, rather than purely elastic or plastic. PMID:21929255

  18. Chain Of Test Contacts For Integrated Circuits

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo

    1989-01-01

    Test structure forms chain of "cross" contacts fabricated together with large-scale integrated circuits. If necessary, number of such chains incorporated at suitable locations in integrated-circuit wafer for determination of fabrication yield of contacts. In new structure, resistances of individual contacts determined: In addition to making it possible to identify local defects, enables generation of statistical distributions of contact resistances for prediction of "parametric" contact yield of fabrication process.

  19. PREFACE: Non-contact AFM Non-contact AFM

    NASA Astrophysics Data System (ADS)

    Giessibl, Franz J.; Morita, Seizo

    2012-02-01

    This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of these conferences are a useful source of information, several key developments warrant devoting a special issue to this subject. In the theoretic field, the possibility of supplementing established techniques such as scanning tunneling microscopy (STM) and Kelvin probe microscopy with atomically resolved force micrsoscopy poses many challenges in the calculation of contrast and contrast reversal. The surface science of insulators, self-assembled monolayers and adsorbates on insulators is a fruitful field for the application of non-contact AFM: several articles in this issue are devoted to these subjects. Atomic imaging and manipulation have been pioneered using STM, but because AFM allows the measurement of forces, AFM has had a profound impact in this field as well. Three-dimensional force spectroscopy has allowed many important insights into surface science. In this issue a combined 3D tunneling and force microscopy is introduced. Non-contact AFM typically uses frequency modulation to measure force gradients and was initially used mainly in a vacuum. As can be seen in this issue, frequency modulation is now also used in ambient conditions, allowing better spatial and force resolution. We thank all of the contributors for their time and efforts in making this special issue possible. We are also very grateful to the staff of IOP Publishing for handling the administrative aspects and for steering the refereeing process. Non-contact AFM contents Relation between the chemical force and the tunnelling current in atomic point contacts: a simple model Pavel Jelínek, Martin Ondrácek and Fernando Flores Theoretical simulation of

  20. Estimating actual, potential, reference crop and pan evaporation using standard meteorological data: a pragmatic synthesis

    NASA Astrophysics Data System (ADS)

    McMahon, T. A.; Peel, M. C.; Lowe, L.; Srikanthan, R.; McVicar, T. R.

    2013-04-01

    This guide to estimating daily and monthly actual, potential, reference crop and pan evaporation covers topics that are of interest to researchers, consulting hydrologists and practicing engineers. Topics include estimating actual evaporation from deep lakes and from farm dams and for catchment water balance studies, estimating potential evaporation as input to rainfall-runoff models, and reference crop evapotranspiration for small irrigation areas, and for irrigation within large irrigation districts. Inspiration for this guide arose in response to the authors' experiences in reviewing research papers and consulting reports where estimation of the actual evaporation component in catchment and water balance studies was often inadequately handled. Practical guides using consistent terminology that cover both theory and practice are not readily available. Here we provide such a guide, which is divided into three parts. The first part provides background theory and an outline of the conceptual models of potential evaporation of Penman, Penman-Monteith and Priestley-Taylor, as well as discussions of reference crop evapotranspiration and Class-A pan evaporation. The last two sub-sections in this first part include techniques to estimate actual evaporation from (i) open-surface water and (ii) landscapes and catchments (Morton and the advection-aridity models). The second part addresses topics confronting a practicing hydrologist, e.g. estimating actual evaporation for deep lakes, shallow lakes and farm dams, lakes covered with vegetation, catchments, irrigation areas and bare soil. The third part addresses six related issues: (i) automatic (hard wired) calculation of evaporation estimates in commercial weather stations, (ii) evaporation estimates without wind data, (iii) at-site meteorological data, (iv) dealing with evaporation in a climate change environment, (v) 24 h versus day-light hour estimation of meteorological variables, and (vi) uncertainty in evaporation

  1. Sensing with Superconducting Point Contacts

    PubMed Central

    Nurbawono, Argo; Zhang, Chun

    2012-01-01

    Superconducting point contacts have been used for measuring magnetic polarizations, identifying magnetic impurities, electronic structures, and even the vibrational modes of small molecules. Due to intrinsically small energy scale in the subgap structures of the supercurrent determined by the size of the superconducting energy gap, superconductors provide ultrahigh sensitivities for high resolution spectroscopies. The so-called Andreev reflection process between normal metal and superconductor carries complex and rich information which can be utilized as powerful sensor when fully exploited. In this review, we would discuss recent experimental and theoretical developments in the supercurrent transport through superconducting point contacts and their relevance to sensing applications, and we would highlight their current issues and potentials. A true utilization of the method based on Andreev reflection analysis opens up possibilities for a new class of ultrasensitive sensors. PMID:22778630

  2. Contact charge-transfer lasers

    SciTech Connect

    Dharamsi, A.N.; Tulip, J.

    1981-07-01

    A mechanism for sustaining population inversions in contact charge-transfer complexes in which the ground electronic state is not bound is described. The mechanism relies on picosecond radiationless depletion of the lower laser state. This generates an inversion even when the ground-state potential curve, as plotted against the donor-acceptor distance, is not repulsive vertically below the excited state minimum. Contact charge-transfer lasers would offer high gain, high-energy density, and tunable sources of coherent radiation in the uv and visible. A method for pumping such a laser is examined and applied to the pyrrole-oxygen complex. A rate equation analysis is done and estimates for gain and energy density are presented.

  3. Contact microscopy with synchrotron radiation

    SciTech Connect

    Panessa-Warren, B.J.

    1985-10-01

    Soft x-ray contact microscopy with synchrotron radiation offers the biologist and especially the microscopist, a way to morphologically study specimens that could not be imaged by conventional TEM, STEM or SEM methods (i.e. hydrated samples, samples easily damaged by an electron beam, electron dense samples, thick specimens, unstained low contrast specimens) at spatial resolutions approaching those of the TEM, with the additional possibility to obtain compositional (elemental) information about the sample as well. Although flash x-ray sources offer faster exposure times, synchrotron radiation provides a highly collimated, intense radiation that can be tuned to select specific discrete ranges of x-ray wavelengths or specific individual wavelengths which optimize imaging or microanalysis of a specific sample. This paper presents an overview of the applications of x-ray contact microscopy to biological research and some current research results using monochromatic synchrotron radiation to image biological samples. 24 refs., 10 figs.

  4. Contact dermatitis caused by preservatives.

    PubMed

    Yim, Elizabeth; Baquerizo Nole, Katherine L; Tosti, Antonella

    2014-01-01

    Preservatives are biocidal chemicals added to food, cosmetics, and industrial products to prevent the growth of microorganisms. They are usually nontoxic and inexpensive and have a long shelf life. Unfortunately, they commonly cause contact dermatitis. This article reviews the most important classes of preservatives physicians are most likely to encounter in their daily practice, specifically isothiazolinones, formaldehyde and formaldehyde-releasers, iodopropynyl butylcarbamate, methyldibromoglutaronitrile, and parabens. For each preservative mentioned, the prevalence of sensitization, clinical presentation of contact dermatitis, patch testing concentrations, cross reactions, and related legislation will be discussed. Mandatory labeling of preservatives is required in some countries, but not required in others. Until policies are made, physicians and patients must be proactive in identifying potential sensitizers and removing their use. We hope that this article will serve as a guide for policy makers in creating legislation and future regulations on the use and concentration of certain preservatives in cosmetics and industrial products. PMID:25207684

  5. Freely suspended quantum point contacts

    NASA Astrophysics Data System (ADS)

    Rössler, C.; Herz, M.; Bichler, M.; Ludwig, S.

    2010-05-01

    We present a versatile design of freely suspended quantum point contacts with particular large one-dimensional subband quantization energies of up to Δɛ≈10 meV. The nanoscale bridges embedding a two-dimensional electron system are fabricated from AlGaAs/GaAs heterostructures by electron-beam lithography and etching techniques. Narrow constrictions define quantum point contacts that are capacitively controlled via local in-plane side gates. Employing transport spectroscopy, we investigate the transition from electrostatic subbands to Landau quantization in a perpendicular magnetic field. The large subband quantization energies allow us to utilize a wide magnetic field range and thereby observe a large exchange split spin-gap of the two lowest Landau-levels.

  6. Allergic contact dermatitis to Alstroemeria.

    PubMed

    Marks, J G

    1988-06-01

    Two female florists developed dermatitis of the fingertips. Patch testing revealed allergic contact dermatitis to the flower, Alstroemeria, used in floral arrangements. They had positive patch tests to portions of Alstroemeria, and to tuliposide A, the allergen in this plant. Vinyl gloves were not helpful since tuliposide A readily penetrates through these gloves. Nitrile gloves may be protective since they prevented positive patch test to tuliposide A. PMID:2967676

  7. [Contact allergies in medical occupations].

    PubMed

    Rustemeyer, T; Pilz, B; Frosch, P J

    1994-12-01

    Based on reports in the literature, data from the information network of German dermatology centres (Informationsverbund Dermatologischer Kliniken) and the authors own findings, a review is presented on prevalence, clinical picture and causative agents of contact allergic dermatoses in health care professions. In 1991 the proportion of suspected occupational diseases in the health care professions (including hairdressers) represented by cases of dermatitis, as reported to the responsible insurance institution, reached 72% of the total for the year (7287 out of 10127). Every 20th to 40th case was recognized as an occupational dermatosis according to German law. Accurate figures on incidence are scarce; for dentists an incidence of 0.11% has been calculated. The risk of developing occupational hand eczema has been shown to be at least three times higher for nurses than for other so-called dry professions. For persons engaged in the personal care of the ill and the elderly, relevant occupational allergens were found to be benzalkonium chloride and aldehydes in disinfectants, as well as rubber accelerators such as thiuram mix. Latex contact urticaria has increasing significance for medical personnel, with prevalence rates of sensitization between 4.5% and 10.7%. Among physicians, contact allergies to thiuram mix were found to be dominant (12.9%). For surgeons and orthopaedic surgeons, methyl methacrylate as a constituent of bone cement is of great importance. Various esters of acrylic acid and methacrylic acid are important sensitizers in the dental professions, particularly in heavily exposed dental laboratory technicians. Only a few gloves protect against these types of sensitizers. Sensitizations by medicaments can be avoided in most cases by reducing direct skin contact, as practiced with penicillin or ispaghula powder. Strategies of prevention include information of atopics regarding the increase in occupational dermatitis, the regular use of barrier creams

  8. [Contact allergy to essential oils].

    PubMed

    Selvåg, E; Holm, J O; Thune, P

    1995-11-10

    Ethereal oils are widely used, in food, toothpaste, as flavouring agents in perfumes and cosmetics, and in dermatological treatment, as antiseptics, adstringenta, antipruritic tinctures, lotions and pomades. The use of ethereal oils seems to have increased in recent years, probably due to a growing interest in alternative medicine, and especially aromatherapy. By describing the cases of three patients with allergic contact dermatitis, we wish to point out possible unwanted side effects of using ethereal oils. PMID:7491578

  9. Contact | Office of Cancer Genomics

    Cancer.gov

    For more information about the Office of Cancer Genomics, please contact: Office of Cancer Genomics National Cancer Institute 31 Center Drive, 10A07 Bethesda, Maryland 20892-2580 Phone: (301) 451-8027 Fax: (301) 480-4368 Email: ocg@mail.nih.gov *Please note that this site will not function properly in Internet Explorer unless you completely turn off the Compatibility View*

  10. Actual drawing of histological images improves knowledge retention.

    PubMed

    Balemans, Monique C M; Kooloos, Jan G M; Donders, A Rogier T; Van der Zee, Catharina E E M

    2016-01-01

    Medical students have to process a large amount of information during the first years of their study, which has to be retained over long periods of nonuse. Therefore, it would be beneficial when knowledge is gained in a way that promotes long-term retention. Paper-and-pencil drawings for the uptake of form-function relationships of basic tissues has been a teaching tool for a long time, but now seems to be redundant with virtual microscopy on computer-screens and printers everywhere. Several studies claimed that, apart from learning from pictures, actual drawing of images significantly improved knowledge retention. However, these studies applied only immediate post-tests. We investigated the effects of actual drawing of histological images, using randomized cross-over design and different retention periods. The first part of the study concerned esophageal and tracheal epithelium, with 384 medical and biomedical sciences students randomly assigned to either the drawing or the nondrawing group. For the second part of the study, concerning heart muscle cells, students from the previous drawing group were now assigned to the nondrawing group and vice versa. One, four, and six weeks after the experimental intervention, the students were given a free recall test and a questionnaire or drawing exercise, to determine the amount of knowledge retention. The data from this study showed that knowledge retention was significantly improved in the drawing groups compared with the nondrawing groups, even after four or six weeks. This suggests that actual drawing of histological images can be used as a tool to improve long-term knowledge retention. PMID:26033842

  11. Contact processes in crowded environments.

    PubMed

    Xu, S-L-Y; Schwarz, J M

    2013-11-01

    Periodically sheared colloids at low densities demonstrate a dynamical phase transition from an inactive to active phase as the strain amplitude is increased. The inactive phase consists of no collisions (contacts) between particles in the steady state limit, while in the active phase collisions persist. To investigate this system at higher densities, we construct and study a conserved-particle-number contact process with three-body interactions, which are potentially more likely than two-body interactions at higher densities. For example, consider one active (diffusing) particle colliding with two inactive (nondiffusing) particles such that they become active and consider spontaneous inactivation. In mean field, this system exhibits a continuous dynamical phase transition. Simulations on square lattices also indicate a continuous transition with exponents similar to those measured for the conserved lattice gas (CLG) model. In contrast, the three-body interaction requiring two active particles to activate one inactive particle exhibits a discontinuous transition. Finally, inspired by kinetically constrained models of the glass transition, we investigate the "caging effect" at even higher particle densities to look for a second dynamical phase transition back to an inactive phase. Square lattice simulations suggest a continuous transition with a new set of exponents differing from both the CLG model and what is known as directed percolation, indicating a potentially new universality class for a contact process with a conserved particle number. PMID:24329237

  12. Three 3-axis accelerometers fixed inside the tyre for studying contact patch deformations in wet conditions

    NASA Astrophysics Data System (ADS)

    Niskanen, Arto J.; Tuononen, Ari J.

    2014-05-01

    The tyre-road contact area was studied visually by means of a high-speed camera and three accelerometers fixed to the inner liner of the tyre carcass. Both methods show a distorted contact area in wet conditions, but interesting differences appeared. First, the contact area in full aquaplaning seems strongly distorted on a glass plate when subjected to visual inspection, while the accelerometers indicate a more even hydrodynamic aquaplaning contact length (CL) across the tyre width. Secondly, the acceleration sensors predict the clear shortening of the CL of the tyre before the critical aquaplaning speed. It can be concluded that the visual contact area and shape are heavily dependent on the transparency of the liquid and smoothness of the glass. Meanwhile, the tyre sensors can provide a CL estimate on any road surface imaginable.

  13. Tibiofemoral cartilage contact biomechanics in patients after reconstruction of a ruptured anterior cruciate ligament.

    PubMed

    Hosseini, Ali; Van de Velde, Samuel; Gill, Thomas J; Li, Guoan

    2012-11-01

    We investigated the in vivo cartilage contact biomechanics of the tibiofemoral joint in patients after reconstruction of a ruptured anterior cruciate ligament (ACL). A dual fluoroscopic and MR imaging technique was used to investigate the cartilage contact biomechanics of the tibiofemoral joint during in vivo weight-bearing flexion of the knee in eight patients 6 months following clinically successful reconstruction of an acute isolated ACL rupture. The location of tibiofemoral cartilage contact, size of the contact area, cartilage thickness at the contact area, and magnitude of the cartilage contact deformation of the ACL-reconstructed knees were compared with those previously measured in intact (contralateral) knees and ACL-deficient knees of the same subjects. Contact biomechanics of the tibiofemoral cartilage after ACL reconstruction were similar to those measured in intact knees. However, at lower flexion, the abnormal posterior and lateral shift of cartilage contact location to smaller regions of thinner tibial cartilage that has been described in ACL-deficient knees persisted in ACL-reconstructed knees, resulting in an increase of the magnitude of cartilage contact deformation at those flexion angles. Reconstruction of the ACL restored some of the in vivo cartilage contact biomechanics of the tibiofemoral joint to normal. Clinically, recovering anterior knee stability might be insufficient to prevent post-operative cartilage degeneration due to lack of restoration of in vivo cartilage contact biomechanics. PMID:22528687

  14. Time experiences, self-actualizing values, and creativity.

    PubMed

    Yonge, G D

    1975-12-01

    The Personal Orientation Inventory (POI), the Inventory of Temporal Experiences (ITE), and the Adjective Check List (ACL) were administered to 80 subjects. Sixteen scores were derived from the POI, 4 from the ITE and a Creativity score for the ACL. The resulting intercorrelations were interpreted in the light of the theories of Maslow and Hugenholtz which postulate a convergence of self-actualization, creativity, and certain experiences of time. The present study presents some evidence for the expected convergence and contributes to the construct validity of several of the variables studied. PMID:1202191

  15. Power Delivery from an Actual Thermoelectric Generation System

    NASA Astrophysics Data System (ADS)

    Kaibe, Hiromasa; Kajihara, Takeshi; Nagano, Kouji; Makino, Kazuya; Hachiuma, Hirokuni; Natsuume, Daisuke

    2014-06-01

    Similar to photovoltaic (PV) and fuel cells, thermoelectric generators (TEGs) supply direct-current (DC) power, essentially requiring DC/alternating current (AC) conversion for delivery as electricity into the grid network. Use of PVs is already well established through power conditioning systems (PCSs) that enable DC/AC conversion with maximum-power-point tracking, which enables commercial use by customers. From the economic, legal, and regulatory perspectives, a commercial PCS for PVs should also be available for TEGs, preferably as is or with just simple adjustment. Herein, we report use of a PV PCS with an actual TEG. The results are analyzed, and proper application for TEGs is proposed.

  16. Interferometric measurement of actual oblique astigmatism of ophthalmic lenses

    NASA Astrophysics Data System (ADS)

    Wihardjo, Erning

    1995-03-01

    A technique for measuring oblique astigmatism error of ophthalmic lenses is described. The technique is based on a Mach-Zehnder interferometer, which allows us to simulate the actual conditions of the eye. The effects of the lens power, the pupilary aperture size and the viewing distance in calculating a projected pupil zone on the lens are discussed. The projected pupil size on the lens affects the measurement result of the oblique astigmatism error. Conversion of the interferogram to astigmatism error in diopters is given.

  17. Nanoscale contact mechanics of biocompatible polyzwitterionic brushes.

    PubMed

    Zhang, Zhenyu; Morse, Andrew J; Armes, Steven P; Lewis, Andrew L; Geoghegan, Mark; Leggett, Graham J

    2013-08-27

    Friction force microscopy has been used to demonstrate that biocompatible, lubricious poly(2-(methacryloyloxy)ethylphosphorylcholine) (PMPC) brushes exhibit different frictional properties depending on the medium (methanol, ethanol, 2-propanol, and water; the latter also with different quantities of added salt). The chemical functionalization of the probe (amine-, carboxylic acid-, and methyl-terminated probes were used) is not as important as the medium in determining the contact mechanics. For solvents such as methanol, where the adhesion between AFM probe and PMPC brushes is negligible, a linear friction-load relationship is observed. In contrast, the friction-load plot is nonlinear in ethanol or water, media in which stronger adhesion is measured. For ethanol, the data indicate Johnson-Kendall-Roberts (JKR) mechanics, whereas the Derjaguin-Muller-Toporov (DMT) model provided a good fit for the data acquired in water. Contact mechanics on zwitterionic PMPC brushes immersed in aqueous solutions of varying ionic strength followed the same trend, with high adhesion energies being correlated with a nonlinear friction-load relationship. These results can be rationalized by treating the friction force as the sum of a load-dependent term, attributed to molecular plowing, and an area-dependent shear term. In a good solvent for PMPC such as methanol, the shear term is negligible and the sliding interaction is dominated by molecular plowing. However, the adhesion energy is significantly larger in water and ethanol and the shear term is no longer negligible. PMID:23855771

  18. Microdroplet evaporation with a forced pinned contact line.

    PubMed

    Gleason, Kevin; Putnam, Shawn A

    2014-09-01

    Experimental and numerical investigations of water microdroplet evaporation on heated, laser patterned polymer substrates are reported. The study is focused on both (i) controlling a droplet's contact line dynamics during evaporation to identifying how the contact line influences evaporative heat transfer and (ii) validating numerical simulations with experimental data. Droplets are formed on the polymer surface using a bottom-up methodology, where a computer-controlled syringe pump feeds water through a 200 μm diameter fluid channel within the heated polymer substrate. This methodology facilitates precise control of the droplet's growth rate, size, and inlet temperature. In addition to this microchannel supply line, the substrate surfaces are laser patterned with a moatlike trench around the fluid-channel outlet, adding additional control of the droplet's contact line motion, area, and contact angle. In comparison to evaporation on a nonpatterned polymer surface, the laser patterned trench increases contact line pinning time by ∼60% of the droplet's lifetime. Numerical simulations of diffusion controlled evaporation are compared the experimental data with a pinned contact line. These diffusion based simulations consistently over predict the droplet's evaporation rate. In efforts to improve this model, a temperature distribution along the droplet's liquid-vapor interface is imposed to account for the concentration distribution of saturated vapor along the interface, which yields improved predictions within 2-4% of the experimental data throughout the droplet's lifetime on heated substrates. PMID:25102248

  19. Contacts for high-resistivity (Cd,Mn)Te crystals

    SciTech Connect

    Witkowska-Baran, M.; James, R.; Mycielski, A.; Kochanowska, D.; Szadkowski, A.J.; Jakiela, R.; Witkowska, B.; Kaliszek, W.; Domagala, J.; Lusakowska, E.; Domukhovski, V.; Dybko, K.; Cui, Y.; and James, R.B.

    2010-09-09

    Semi-insulating (Cd,Mn)Te crystals offer a material that may compete well with the commonly used (Cd,Zn)Te crystals for manufacturing large-area X- and gamma-ray detectors. The Bridgman growth method yields good quality, high-resistivity (10{sup 9} - 10{sup 10} {Omega} {center_dot} cm) crystals of (Cd,Mn)Te:V. Doping the as-grown crystals with the compensating agent vanadium ({approx} 10{sup 16} cm{sup -3}) ensures their high resistivity; thereafter, annealing them in cadmium vapors reduces the number of cadmium vacancies. Applying the crystals as detectors necessitates having satisfactory electrical contacts. Accordingly, we explored various techniques of ensuring good electrical contacts to these semi-insulating (Cd,Mn)Te crystals, assessing metallic layers, monocrystalline semiconductor layers, and amorphous (or nanocrystalline) semiconductor layers. We found that ZnTe heavily doped ({approx} 10{sup 18} cm{sup -3}) with Sb, and CdTe heavily doped ({approx} 10{sup 17} cm{sup -3}) with In, proved satisfactory semiconductor contact layers. They subsequently enabled us to establish good contacts (with only narrow tunneling barriers) to the Au layer that usually constitutes the most external contact layer. We outline our technology of applying electrical contacts to semi-insulating (Cd,Mn)Te, and describe some important properties.

  20. Frontoparietal cortex and cerebellum contribution to the update of actual and mental motor performance during the day

    PubMed Central

    Bonzano, Laura; Roccatagliata, Luca; Ruggeri, Piero; Papaxanthis, Charalambos; Bove, Marco

    2016-01-01

    Actual and imagined movement speed increases from early morning until mid-afternoon. Here, we investigated the neural correlates of these daily changes. Fifteen subjects performed actual and imagined right finger opposition movement sequences at 8 am and 2 pm. Both actual and imagined movements were significantly faster at 2 pm than 8 am. In the morning, actual movements significantly activated the left primary somatosensory and motor areas, and bilaterally the cerebellum; in the afternoon activations were similar but reduced. Contrast analysis revealed greater activity in the cerebellum, the left primary sensorimotor cortex and parietal lobe in the morning than in the afternoon. Imagined movements in the morning significantly activated the parietal association cortices bilaterally, the left supplementary and premotor areas, and the right orbitofrontal cortex and cerebellum. In the afternoon, the frontal lobe was significantly activated with the right cerebellum. Contrast analysis revealed increased activity in the left parietal lobe in the morning than in the afternoon. For both tasks, speed in the morning was significantly related to the BOLD signal in the brain areas resulted more active. These findings suggest that motor performance is continuously updated on a daily basis with a predominant role of the frontoparietal cortex and cerebellum. PMID:27444783

  1. Tibiofemoral contact biomechanics following meniscocapsular separation and repair.

    PubMed

    Dugas, J R; Barrett, A M; Beason, D P; Plymale, M F; Fleisig, G S

    2015-06-01

    Meniscocapsular separations are often seen in knees with other intra-articular pathology. The consequences of these tears with regard to knee contact mechanics are currently unknown, and the biomechanical advantages of repair have not been measured. We hypothesize that tears to the meniscocapsular junction will cause an increase in tibiofemoral contact pressure and a decrease in contact area, with a return to more normal conditions after repair. 10 fresh-frozen cadaver knees each underwent 10 cycles of axial compressive loading in full extension under three different testing conditions: intact, meniscocapsular separation, and repair. A pressure sensor matrix was inserted into the medial joint space and used to measure magnitude and location of contact pressure and area. Mean contact pressure increased from 0.80±0.17 MPa in the intact knee to 0.88±0.19 MPa with separation, with a decrease to 0.78±0.14 MPa following repair. Peak pressures followed a similar trend with 2.59±0.41, 3.03±0.48, and 2.84±0.40 MPa for the same three groups, respectively. While none of the changes seen was statistically significant, even these small changes would potentially create degenerative changes at the articular surface over prolonged (i. e., months or years) standing, walking, and activity in the unrepaired state. PMID:25734910

  2. Image based weighted center of proximity versus directly measured knee contact location during simulated gait.

    PubMed

    Wang, Hongsheng; Chen, Tony; Koff, Matthew F; Hutchinson, Ian D; Gilbert, Susannah; Choi, Dan; Warren, Russell F; Rodeo, Scott A; Maher, Suzanne A

    2014-07-18

    To understand the mechanical consequences of knee injury requires a detailed analysis of the effect of that injury on joint contact mechanics during activities of daily living. Three-dimensional (3D) knee joint geometric models have been combined with knee joint kinematics to dynamically estimate the location of joint contact during physiological activities-using a weighted center of proximity (WCoP) method. However, the relationship between the estimated WCoP and the actual location of contact has not been defined. The objective of this study was to assess the relationship between knee joint contact location as estimated using the image-based WCoP method, and a directly measured weighted center of contact (WCoC) method during simulated walking. To achieve this goal, we created knee specific models of six human cadaveric knees from magnetic resonance imaging. All knees were then subjected to physiological loads on a knee simulator intended to mimic gait. Knee joint motion was captured using a motion capture system. Knee joint contact stresses were synchronously recorded using a thin electronic sensor throughout gait, and used to compute WCoC for the medial and lateral plateaus of each knee. WCoP was calculated by combining knee kinematics with the MRI-based knee specific model. Both metrics were compared throughout gait using linear regression. The anteroposterior (AP) location of WCoP was significantly correlated with that of WCoC on both tibial plateaus in all specimens (p<0.01, 95% confidence interval of Pearson׳s coefficient r>0), but the correlation was not significant in the mediolateral (ML) direction for 4/6 knees (p>0.05). Our study demonstrates that while the location of joint contact obtained from 3D knee joint contact model, using the WCoP method, is significantly correlated with the location of actual contact stresses in the AP direction, that relationship is less certain in the ML direction. PMID:24837219

  3. Direct-Write Contacts: Metallization and Contact Formation; Preprint

    SciTech Connect

    van Hest, M. F. A. M.; Curtis, C. J.; Miedaner, A.; Pasquarelli, R. M.; Kaydonova, T.; Hersh, P.; Ginley, D. S.

    2008-05-01

    Using direct-write approaches in photovoltaics for metallization and contact formation can significantly reduce the cost per watt of producing photovoltaic devices. Inks have been developed for various materials, such as Ag, Cu, Ni and Al, which can be used to inkjet print metallizations for various kinds of photovoltaic devices. Use of these inks results in metallization with resistivities close to those of bulk materials. By means of inkjet printing a metallization grid can be printed with better resolution, i.e. smaller lines, than screen-printing. Also inks have been developed to deposit transparent conductive oxide films by means of ultrasonic spraying.

  4. Influence of different narrative instructions to record the occlusal contact with silicone registration materials.

    PubMed

    Obara, R; Komiyama, O; Iida, T; Asano, T; De Laat, A; Kawara, M

    2014-03-01

    This study examined the influence of narrative instructions on the occlusal contact area, occlusal contact point and masticatory muscle activities in normal subjects. Twelve healthy men and 12 healthy women with no more than one missing tooth per quadrant participated. Surface EMG was recorded from the masseter and temporal muscle. As a control measurement, intercuspal position was maintained to produce a habitual clenching record (NCR) while the occlusal contact area and occlusal contact point was recorded by means of silicone material. Subsequently, the occlusal contact area was recorded with the narrative instruction for minimum clenching record (MCR), light clenching record (LCR) and strong clenching record (HCR). While the EMG activity (%MVC) increased modestly from MCR to LCR (from 9·3 ± 2·0% to 11·5 ± 1·5%), the occlusal contact area increased rapidly (from 17·2 ± 11·3 mm(2) to 26·8 ± 15·6 mm(2) ) (P < 0·05). Both EMG activity and occlusal contact area increased gradually from LCR to NCR (to 17·7 ± 2·0% and to 31·4 ± 14·2 mm(2) , respectively). Finally, EMG activity still increased from NCR to HCR (to 44·5 ± 3·7%) (P < 0·05), but the occlusal contact area remained stable (to 36·8 ± 16·6 mm(2) ). Occlusal contact points at left posterior, right posterior, anterior and total area were not significantly different between each task. This study showed that narrative instructions while recording the bite can result in largely stable occlusal contact area. An adequate narrative instruction may therefore contribute to taking a stable occlusal recording in natural dentition. PMID:24447195

  5. Using the fact that wetting is contact line dependent.

    PubMed

    Cheng, Dalton F; McCarthy, Thomas J

    2011-04-01

    Two series of experiments, both involving contact line pinning, are reported that were designed using the contact line perspective of wetting and require this perspective to explain the observed results. Perspectives based on contact areas, for example, Wenzel's and Cassie's, are not useful in either of these experimental situations. In the first type of experiment described, sessile water drops were pinned on low contact angle hysteresis surfaces using 40 different shape/size lithographed hydrophilic features. Hydrophilic arcs (sections of circles), short wedges (pointed to the center of the circle), long wedges (pointed to the opposite side of the circle), and the upper outlines of the short and long wedges were prepared and studied. These features were based on circles with diameters of 4 and 6 mm and arcs of 30°, 60°, 90°, and 120°. The volume of water that could be pinned depends on the linear shape of the portion of the feature that interacts with the receding contact line and not on the feature area. In the second type of experiment, thin hydrophilic contact lines were used to support films of water (puddles and kinetically trapped thin films) on water-repellent surfaces and used to control the shape (both 2D and 3D) of these thin films and puddles. Elongated water puddles, 60 mm long and 4 mm wide, were prepared using contact line patterns with line widths of 500, 250, and 100 μm. Curved puddles, geometric shapes, letters of the English alphabet, and puddles with variable liquid thicknesses (heights) were also prepared. PMID:21381673

  6. Assessment of surface contamination with contact mechanics

    SciTech Connect

    EMERSON,JOHN A.; MILLER,GREGORY V.; SORENSEN,CHRISTOPHER R.; PEARSON,RAYMOND A.

    2000-02-21

    The authors are particularly interested in the work of adhesion measurements as a means to facilitate the understanding of the adhesive failure mechanisms for systems containing encapsulated and bonded components. Of the several issues under investigation, one is the effect of organic contamination on the adhesive strength for several types of polymer/metal interface combinations. The specific question that the authors are trying to address is at what level of contamination does adhesive strength decrease. The use of contact mechanics, the JKR method, is a good approach for studying this question. Another approach being studied is the use of interracial fracture mechanics. The model contaminant is hexadecane--non-polar, medium molecular weight hydrocarbon fluid. They choose hexadecane because it replicates typical machining fluids, is nonreactive with Al surfaces, and should not dissolve readily into the adhesive systems of interest. The application of a uniform, controllable and reproducible hexadecane layer on Al surfaces has proven to be difficult. A primary concern is whether studies of model systems can be extended to systems of technological interest. The JKR theory is a continuum mechanics model of contact between two solid spheres that was developed by Johnson, Kendall and Roberts. The JKR theory is an extension of Hertzian contact theory and attributes the additional increase in the contact area between a soft elastomeric hemisphere to adhesive forces between the two surfaces. The JKR theory allows a direct estimate of the surface free energy of interface as well as the work of adhesion (Wa) between solids. Early studies performed in this laboratory involved the determination of Wa between silicone (PDMS) and Al surfaces in order to establish the potential adhesive failure mechanisms. However, the JKR studies using commercial based PDMS [poly(dimethylsiloxane)] was fraught with difficulty that were attributed to the additives used in commercial PDMS

  7. Experimental study on the regenerator under actual operating conditions

    NASA Astrophysics Data System (ADS)

    Nam, Kwanwoo; Jeong, Sangkwon

    2002-05-01

    An experimental apparatus was prepared to investigate thermal and hydrodynamic characteristics of the regenerator under its actual operating conditions. The apparatus included a compressor to pressurize and depressurize regenerator with various operating frequencies. Cold end of the regenerator was maintained around 100 K by means of liquid nitrogen container and heat exchanger. Instantaneous gas temperature and mass flow rate were measured at both ends of the regenerator during the whole pressure cycle. Pulsating pressure and pressure drop across the regenerator were also measured. The operating frequency of the pressure cycle was varied between 3 and 60 Hz, which are typical operating frequencies of Gifford-McMahon, pulse tube, and Stirling cryocoolers. First, friction factor for the wire screen mesh was directly determined from room temperature experiments. When the operating frequency was less than 9 Hz, the oscillating flow friction factor was nearly same as the steady flow friction factor for Reynolds number up to 100. For 60 Hz operations, the ratio of oscillating flow friction factor to steady flow one was increased as hydraulic Reynolds number became high. When the Reynolds number was 100, this ratio was about 1.6. Second, ineffectiveness of the regenerator was obtained when the cold-end was maintained around 100 K and the warm-end at 300 K to simulate the actual operating condition of the regenerator in cryocooler. Effect of the operating frequency on ineffectiveness of regenerator was discussed at low frequency range.

  8. Discrete dislocation plasticity analysis of contact between deformable bodies of simple geometry

    NASA Astrophysics Data System (ADS)

    Siang, Kelvin Ng Wei; Nicola, Lucia

    2016-05-01

    A contact mechanical model is presented where both metal bodies can deform by discrete dislocation plasticity. The model intends to improve on previous dislocation dynamics models of contact, where only a plastically deformable body was considered, flattened by a rigid platen. The effect of the rigid platen was mimicked through boundary conditions acting on the deformable body. While the formulation is general, the simulations presented here are only performed for contact between a plastically deforming body with sinusoidal surface and a flat body that is either elastic or rigid. Results show that the contact conditions, i.e. frictionless and full stick, affect the morphology of the contact as well as the contact pressure distribution. This is because dislocations can glide through the frictionless contact and fragment it, but do not penetrate a sticking contact. Average quantities like mean apparent contact pressure and total plastic slip are, instead, independent of contact conditions and of the details of the contact area. A size dependence is observed in relation to the onset of plastic deformation, where surfaces with smaller wavelength and amplitude require a larger contact pressure to yield than self similar surfaces with larger wavelength. The size dependence is very pronounced when the flat body is rigid, but fades when the compliance of the flat body is large.

  9. Influence of axial self-magnetic field component on arcing behavior of spiral-shaped contacts

    SciTech Connect

    Feng, Dingyu; Xiu, Shixin Wang, Yi; Liu, Gang; Zhang, Yali; Bi, Dongli

    2015-10-15

    The transverse magnetic field (TMF) contact design is commonly used in vacuum interrupters. When arcing occurs between the TMF contacts, the contact structure can create a self-induced magnetic field that drives the arc to move and rotate on the contact, and thus local overheating and severe erosion can be avoided. However, TMF contacts could also create an axial self-magnetic component, and the influence of this component on the arc behavior has not been considered to date. In this paper, five different types of Cu-Cr spiral-shaped TMF contacts with three different structures are investigated in a demountable vacuum chamber that contains a high-speed charge-coupled device video camera. It was found that the contact structure greatly influenced the arc behavior, especially in terms of arc rotation and the effective contact area, while contacts with the same slot structure but different diameters showed similar arc behavior and arc motion. The magnetic field distribution and the Lorentz force of each of the three different contact structures are simulated, and the axial self-magnetic field was first taken into consideration for investigation of the TMF contact design. It was found that contact designs that have higher axial self-magnetic field components tend to have arc columns with larger diameters and show poorer arc motion and rotation performance in the experiments.

  10. Allergic contact dermatitis from a wooden necklace.

    PubMed

    Hausen, B M

    1997-09-01

    A 36-year-old female kitchenworker twice developed eczematous lesions corresponding exactly to the area around her neck where she had worn a wooden necklace. Contact dermatitis lasted longer than 1 week. The necklace consisted of 42 brown wooden beads and 63 other wooden parts, 0.5 to 3 cm diameter. Most parts could be identified as Cocobolo wood, Brazilian and East Indian rosewood, and teak. Patch tests with the pure constituents gave +3-reactions to three dalbergions and obtusaquinone, which are known to be the sensitizers of Cocobolo and the above-mentioned rosewoods. Because of these test results, the identification of the species by eye examination could be corroborated. Further detailed questioning revealed that the patient had played a recorder, probably made from Cocobolo (Dalbergia retusa), when a child, to which she unknowingly became allergic. PMID:9249295

  11. Contact Dermatitis, Patch Testing, and Allergen Avoidance.

    PubMed

    Burkemper, Nicole M

    2015-01-01

    In patients presenting with a complaint of rash, contact dermatitis is often the underlying diagnosis making it an entity with which health care providers should be familiar. Contact dermatitis can be divided into irritant contact dermatitis and allergic contact dermatitis. In a patient suspected of having allergic contact dermatitis, patch testing can be done to identify specific allergens. Education focused on allergen avoidance and safe products is an integral part of treatment for the contact dermatitis patient. Knowledge of the most common allergens is helpful for clinicians to be able to provide this education. PMID:26455061

  12. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2014-07-22

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline materiat layer; and forming conductive contacts in the plurality of contact holes.

  13. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David D.; Cousins, Peter John

    2015-07-21

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  14. Solar cell contact formation using laser ablation

    DOEpatents

    Harley, Gabriel; Smith, David; Cousins, Peter

    2012-12-04

    The formation of solar cell contacts using a laser is described. A method of fabricating a back-contact solar cell includes forming a poly-crystalline material layer above a single-crystalline substrate. The method also includes forming a dielectric material stack above the poly-crystalline material layer. The method also includes forming, by laser ablation, a plurality of contacts holes in the dielectric material stack, each of the contact holes exposing a portion of the poly-crystalline material layer; and forming conductive contacts in the plurality of contact holes.

  15. Low resistance contacts for shallow junction semiconductors

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S. (Inventor); Weizer, Victor G. (Inventor)

    1994-01-01

    A method of enhancing the specific contact resistivity in InP semiconductor devices and improved devices produced thereby are disclosed. Low resistivity values are obtained by using gold ohmic contacts that contain small amounts of gallium or indium and by depositing a thin gold phosphide interlayer between the surface of the InP device and the ohmic contact. When both the thin interlayer and the gold-gallium or gold-indium contact metallizations are used, ultra low specific contact resistivities are achieved. Thermal stability with good contact resistivity is achieved by depositing a layer of refractory metal over the gold phosphide interlayer.

  16. Some practical considerations for economical back contact formation on high efficiency solar cells

    NASA Technical Reports Server (NTRS)

    Lesk, I. A.

    1985-01-01

    The back contact can detract from solar cell performance in a number of ways: high recombination, barrier, photovoltaic, minority carrier collection, resistance. These effects may act in a nonuniform fashion over the cell area, and complicate the analysis of photovoltaic performance aimed at a better understanding of the effects of device geometry and material and/or processing parameters. The back contact is tested by reproducing it on both sides of a substrate. The objective is to find a back contact which performs well as a back contact, can be applied cheaply to large area solar cells, fits well into a practical process sequence, does not introduce structural damage or undesirable impurities into the silicon substrate, is compatible with an effective front contact technology, permits low temperature solder contacting, adheres well to silicon, and is reliable.

  17. Direct observation of frictional contacts: New insights for state-dependent properties

    USGS Publications Warehouse

    Dieterich, J.H.; Kilgore, B.D.

    1994-01-01

    Rocks and many other materials display a rather complicated, but characteristic, dependence of friction on sliding history. These effects are well-described by empirical rate- and state-dependent constitutive formulations which have been utilized for analysis of fault slip and earthquake processes. We present a procedure for direct quantitative microscopic observation of frictional contacts during slip. The observations reveal that frictional state dependence represents an increase of contact area with contact age. Transient changes of sliding resistance correlate with changes in contact area and arise from shifts of contact population age. Displacement-dependent replacement of contact populations is shown to cause the diagnostic evolution of friction over a characteristic sliding distance that occurs whenever slip begins or sliding conditions change. ?? 1994 Birkha??user Verlag.

  18. New flange correction formula applied to interfacial resistance measurements of ohmic contacts to GaAs

    NASA Technical Reports Server (NTRS)

    Lieneweg, Udo; Hannaman, David J.

    1987-01-01

    A quasi-two-dimensional analytical model is developed to account for vertical and horizontal current flow in and adjacent to a square ohmic contact between a metal and a thin semiconducting strip which is wider than the contact. The model includes side taps to the contact area for voltage probing and relates the 'apparent' interfacial resistivity to the (true) interfacial resistivity, the sheet resistance of the semiconducting layer, the contact size, and the width of the 'flange' around the contact. This relation is checked against numerical simulations. With the help of the model, interfacial resistivities of ohmic contacts to GaAs were extracted and found independent of contact size in the range of 1.5-10 microns.

  19. Shigella Infections in Household Contacts of Pediatric Shigellosis Patients in Rural Bangladesh.

    PubMed

    George, Christine Marie; Ahmed, Shahnawaz; Talukder, Kaisar A; Azmi, Ishrat J; Perin, Jamie; Sack, R Bradley; Sack, David A; Stine, O Colin; Oldja, Lauren; Shahnaij, Mohammad; Chakraborty, Subhra; Parvin, Tahmina; Bhuyian, Sazzadul Islam; Bouwer, Edward; Zhang, Xiaotong; Hasan, Trisheeta N; Luna, Sharmin J; Akter, Fatema; Faruque, Abu S G

    2015-11-01

    To examine rates of Shigella infections in household contacts of pediatric shigellosis patients, we followed contacts and controls prospectively for 1 week after the index patient obtained care. Household contacts of patients were 44 times more likely to develop a Shigella infection than were control contacts (odds ratio 44.7, 95% CI 5.5-361.6); 29 (94%) household contacts of shigellosis patients were infected with the same species and serotype as the index patient's. Pulsed-field gel electrophoresis showed that 14 (88%) of 16 with infected contacts had strains that were indistinguishable from or closely related to the index patient's strain. Latrine area fly counts were higher in patient households compared with control households, and 2 patient household water samples were positive for Shigella. We show high susceptibility of household contacts of shigellosis patients to Shigella infections and found environmental risk factors to be targeted in future interventions. PMID:26484778

  20. Shigella Infections in Household Contacts of Pediatric Shigellosis Patients in Rural Bangladesh

    PubMed Central

    Ahmed, Shahnawaz; Talukder, Kaisar A.; Azmi, Ishrat J.; Perin, Jamie; Sack, R. Bradley; Sack, David A; Stine, O. Colin; Oldja, Lauren; Shahnaij, Mohammad; Chakraborty, Subhra; Parvin, Tahmina; Bhuyian, Sazzadul Islam; Bouwer, Edward; Zhang, Xiaotong; Hasan, Trisheeta N.; Luna, Sharmin J.; Akter, Fatema; Faruque, Abu S.G.

    2015-01-01

    To examine rates of Shigella infections in household contacts of pediatric shigellosis patients, we followed contacts and controls prospectively for 1 week after the index patient obtained care. Household contacts of patients were 44 times more likely to develop a Shigella infection than were control contacts (odds ratio 44.7, 95% CI 5.5–361.6); 29 (94%) household contacts of shigellosis patients were infected with the same species and serotype as the index patient’s. Pulsed-field gel electrophoresis showed that 14 (88%) of 16 with infected contacts had strains that were indistinguishable from or closely related to the index patient’s strain. Latrine area fly counts were higher in patient households compared with control households, and 2 patient household water samples were positive for Shigella. We show high susceptibility of household contacts of shigellosis patients to Shigella infections and found environmental risk factors to be targeted in future interventions. PMID:26484778

  1. An Experimental-Numerical Evaluation of Thermal Contact Conductance in Fin-Tube Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Kim, Chang Nyung; Jeong, Jin; Youn, Baek; Kil, Seong Ho

    The contact between fin collar and tube surface of a fin-tube heat exchanger is secured through mechanical expansion of tubes. However, the characteristics of heat transfer through the interfaces between the tubes and fins have not been clearly understood because the interfaces consist partially of metal-to-metal contact and partially of air. The objective of the present study is to develop a new method utilizing an experimental-numerical method for the estimation of the thermal contact resistance between the fin collar and tube surface and to evaluate the factors affecting the thermal contact resistance in a fin-tube heat exchanger. In this study, heat transfer characteristics of actual heat exchanger assemblies have been tested in a vacuum chamber using water as an internal fluid, and a finite difference numerical scheme has been employed to reduce the experimental data for the evaluation of the thermal contact conductance. The present study has been conducted for fin-tube heat exchangers of tube diameter of 7mm with different tube expansion ratios, fin spacings, and fin types. The results show, with an appropriate error analysis, that these parameters as well as hydrophilic fin coating affect notably the thermal contact conductance. It has been found out that the thermal contact resistance takes fairly large portion of the total thermal resistance in a fin-tube heat exchanger and it turns out that careful consideration is needed in a manufacturing process of heat exchangers to reduce the thermal contact resistance.

  2. Representative Contact Diaries for Modeling the Spread of Infectious Diseases in Taiwan

    PubMed Central

    Fu, Yang-chih; Wang, Da-Wei; Chuang, Jen-Hsiang

    2012-01-01

    Recent studies of infectious diseases have attempted to construct more realistic parameters of interpersonal contact patterns from diary-approach surveys. To ensure that such diary-based contact patterns provide accurate baseline data for policy implementation in densely populated Taiwan, we collected contact diaries from a national sample, using 3-stage systematic probability sampling and rigorous in-person interviews. A representative sample of 1,943 contact diaries recorded a total of 24,265 wide-range, face-to-face interpersonal contacts during a 24-hour period. Nearly 70% of the contacts occurred outside of respondents' households. The most active age group was schoolchildren (ages 5–14), who averaged around 16–18 daily contacts, about 2–3 times as many as the least active age groups. We show how such parameters of contact patterns help modify a sophisticated national simulation system that has been used for years to model the spread of pandemic diseases in Taiwan. Based on such actual and representative data that enable researchers to infer findings to the whole population, our analyses aim to facilitate implementing more appropriate and effective strategies for controlling an emerging or pandemic disease infection. PMID:23056193

  3. Towards an optimal contact metal for CNTFETs.

    PubMed

    Fediai, Artem; Ryndyk, Dmitry A; Seifert, Gotthard; Mothes, Sven; Claus, Martin; Schröter, Michael; Cuniberti, Gianaurelio

    2016-05-21

    Downscaling of the contact length Lc of a side-contacted carbon nanotube field-effect transistor (CNTFET) is challenging because of the rapidly increasing contact resistance as Lc falls below 20-50 nm. If in agreement with existing experimental results, theoretical work might answer the question, which metals yield the lowest CNT-metal contact resistance and what physical mechanisms govern the geometry dependence of the contact resistance. However, at the scale of 10 nm, parameter-free models of electron transport become computationally prohibitively expensive. In our work we used a dedicated combination of the Green function formalism and density functional theory to perform an overall ab initio simulation of extended CNT-metal contacts of an arbitrary length (including infinite), a previously not achievable level of simulations. We provide a systematic and comprehensive discussion of metal-CNT contact properties as a function of the metal type and the contact length. We have found and been able to explain very uncommon relations between chemical, physical and electrical properties observed in CNT-metal contacts. The calculated electrical characteristics are in reasonable quantitative agreement and exhibit similar trends as the latest experimental data in terms of: (i) contact resistance for Lc = ∞, (ii) scaling of contact resistance Rc(Lc); (iii) metal-defined polarity of a CNTFET. Our results can guide technology development and contact material selection for downscaling the length of side-contacts below 10 nm. PMID:27124382

  4. [Natural history of the infection for human papillomavirus: an actualization].

    PubMed

    Martínez, Gerardo González; Troconis, José Núñez

    2014-03-01

    In recent years, there have been major advances in our understanding of the biology and natural history of Human Papilloma Virus (HPV). Most papillomavirus infections are transmitted by close contact of either skin to skin or mucosa to mucosa. Sexual intercourse is not a requirement for genital HPV infection. Digital-oral infections occur and there is evidence that digital-genital and oral-genital contacts can result in the transmission of HPV, although in a relatively low percentage. Vertical transmission from mother to fetus is a common route of infection; in fact, it is recognized that more than 80% of infants born from mothers infected with genital HPV will be positive for HPV DNA determination in the nasal-pharyngeal region and oral mucosa. Women with transient infections often develop cytological abnormalities that take place while there is active HPV replication. This occurs because productive HPV infections result in cytological abnormalities in infected epithelial cells. The strong association between the risk of HPV infection and increased immune suppression, supports a direct biological effect of Human Immunodeficiency Virus (HIV) infection on the natural history of HPV. PMID:24758104

  5. Actual Versus Predicted Cardiovascular Demands in Submaximal Cycle Ergometer Testing

    PubMed Central

    HOEHN, AMANDA M.; MULLENBACH, MEGAN J.; FOUNTAINE, CHARLES J.

    2015-01-01

    The Astrand-Rhyming cycle ergometer test (ARCET) is a commonly administered submaximal test for estimating aerobic capacity. Whereas typically utilized in clinical populations, the validity of the ARCET to predict VO2max in a non-clinical population, especially female, is less clear. Therefore, the purpose of this study was to determine the accuracy of the ARCET in a sample of healthy and physically active college students. Subjects (13 females, 10 males) performed a maximal cycle ergometer test to volitional exhaustion to determine VO2max. At least 48 hours later, subjects performed the ARCET protocol. Predicted VO2max was calculated following the ARCET format using the age corrected factor. There was no significant difference (p=.045) between actual (41.0±7.97 ml/kg/min) and predicted VO2max (40.3±7.58 ml/kg/min). When split for gender there was a significant difference between actual and predicted VO2 for males, (45.1±7.74 vs. 42.7±8.26 ml/kg/min, p=0.029) but no significant difference observed for females, (37.9±6.9 vs. 38.5±6.77 ml/kg/min, p=0.675). The correlation between actual and predicted VO2 was r=0.84, p<0.001 with an SEE= 4.3 ml/kg/min. When split for gender, the correlation for males was r=0.94, p<0.001, SEE=2.72 ml/kg/min; for females, r=0.74, p=0.004, SEE=4.67 ml/kg/min. The results of this study indicate that the ARCET accurately estimated VO2max in a healthy college population of both male and female subjects. Implications of this study suggest the ARCET can be used to assess aerobic capacity in both fitness and clinical settings where measurement via open-circuit spirometry is either unavailable or impractical. PMID:27182410

  6. Seeking Contact: Issues to Consider

    NASA Astrophysics Data System (ADS)

    Michaud, M.

    Seeking contact with extraterrestrial intelligence is a species enterprise that should be conducted with our shared interests in mind. We must reflect on the full range of possible outcomes; we cannot opt out of the potential consequences of actions taken by small numbers of our fellow humans. Until we have empirical evidence about alien technological civilizations, we can reason about them only by analogy with our own history and behaviour. Given that record, some degree of prudence is in order. To conduct this debate more rationally, we must free our thinking of excessively binary stereotypes.

  7. Thermal Conductances Of Metal Contacts

    NASA Technical Reports Server (NTRS)

    Salerno, L. J.; Kittel, P.; Scherkenbach, F. E.; Spivak, A. L.

    1988-01-01

    Report presents results of measurements of thermal conductances of aluminum and stainless-steel contacts at temperatures from 1.6 to 6.0 K. Measurement apparatus includes gearmotor assembly connected to rocker arm by music wire to load sample pair with forces up to 670 N. Heater placed above upper sample. Germanium resistance thermometers in upper and lower samples measured temperature difference across interface over range of heater powers from 0.1 to 10.0 mW. The thermal conductance calculated from temperature difference. Measurements provide data for prediction of thermal conductances of bolted joints in cryogenic infrared instruments.

  8. Smart contact oscillations by IPMCs

    NASA Astrophysics Data System (ADS)

    Asanuma, H.; Asaka, K.; Su, J.; Poubel, L.; Shahinpoor, M.

    2016-02-01

    An ion migration-induced self-oscillation phenomenon observed in ionic polymer metal composites (IPMCs) is reported. These oscillations are generated from a purely static equilibrium configuration of IPMCs in loose contact with a stationary electrode, and in particular the anode of an imposed DC voltage source. Many interesting possibilities emerge, which are described in this paper. Of particular importance is the emergence of the possibility of creating tailor-made electric signals or pulse-width modulation-type signals from a DC source.

  9. Frictionless contact of aircraft tires

    NASA Technical Reports Server (NTRS)

    Kim, Kyun O.; Tanner, John A.; Noor, Ahmed K.

    1989-01-01

    A computational procedure for the solution of frictionless contact problems of spacecraft tires was developed using a two-dimensional laminated anisotropic shell theory incorporating the effects of variations in material and geometric parameters, transverse shear deformation, and geometric nonlinearities to model the nose-gear tire of a space shuttle. Numerical results are presented for the case when the nose-gear tire is subjected to inflation pressure and pressed against a rigid pavement. The results are compared with experimental results obtained at NASA Langley, demonstrating a high accuracy of the model and the effectiveness of the computational procedure.

  10. Self-Actualization in a Marathon Growth Group: Do the Strong Get Stronger?

    ERIC Educational Resources Information Center

    Kimball, Ronald; Gelso, Charles J.

    1974-01-01

    This study examined the effects of a weekend marathon on the level of self-actualization of college students and the relationship between ego strength and extent of change in self-actualization. The group experience did increase self-actualization, but participants' initial level of ego strength was unrelated to changes in self-actualization.…

  11. Analysis and numerical simulation of rolling contact between sphere and cone

    NASA Astrophysics Data System (ADS)

    Zhao, Yanling; Xia, Chengtao; Wang, Hongbo; Xuan, Jiaping; Xiang, Jingzhong; Liu, Xianli; Su, Xiangguo

    2015-05-01

    In non-conforming rolling contact, the contact stress is highly concentrated in the contact area. However, there are some limitations of the special contact model and stress model used for the theoretical study of the phenomenon, and this has prevented in-depth analysis of the associated friction, wear, and failure. This paper is particularly aimed at investigating the area of rolling contact between a sphere and a cone, for which purpose the boundary is determined by the Hertz theory and the geometries of the non-conforming surfaces. The phenomenon of stick-slip contact is observed to occur in the contact area under the condition of no-full-slip (Q < μ · P). Using the two-dimensional rolling contact theory developed by CARTER, the relative positions of the stick and slip regions and the distribution of the tangential force over the contact area are analyzed. Furthermore, each stress component is calculated based on the McEwen theory and the idea of narrow band. The stress equations for the three-dimensional rolling contact between the sphere and the cone are obtained by the principle of superposition, and are used to perform some numerical simulations. The results show that the stress components have a large gradient along the boundary between the stick and slip regions, and that the maximum stress is inversely proportional to the contact coefficient and proportional to the friction coefficient. A new method for investigating the stress during non-classical three-dimensional rolling contact is proposed as a theoretical foundation for the analysis of the associated friction, wear, and failure.

  12. Analysis of contact mechanics in McKee-farrar metal-on-metal hip implants.

    PubMed

    Yew, A; Jagatia, M; Ensaff, H; Jin, Z M

    2003-01-01

    Contact mechanics analysis for a typical McKee-Farrar metal-on-metal hip implant was carried out in this study. The finite element method was used to predict the contact area and the contact pressure distribution at the bearing surfaces. The study investigated the effects of the cement and underlying bone, the geometrical parameters such as the radial clearance between the acetabular cup and the femoral head, and the acetabular cup thickness, as well as other geometrical features on the acetabular cup such as lip and studs. For all the cases considered, the predicted contact pressure distribution was found to be significantly different from that based upon the classical Hertz contact theory, with the maximum value being away from the centre of the contact region. The lip on the cup was found to have a negligible effect on the predicted contact pressure distribution. The presence of the studs on the outside of the cup caused a significant increase in the local contact pressure distribution, and a slight decrease in the contact region. Reasonably good agreement of the predicted contact pressure distribution was found between a three-dimensional anatomical model and a simple two-dimensional axisymmetric model. The interfacial boundary condition between the acetabular cup and the underlying cement, modelled as perfectly fixed or perfectly unbonded, had a negligible effect on the predicted contact parameters. For a given radial clearance of 0.079 mm, the decrease in the thickness of the acetabular cup from 4.5 to 1.5 mm resulted in an increase in the contact half angle from 15 degrees to 26 degrees, and a decrease in the maximum contact pressure from 55 to 20 MPa. For a given acetabular cup thickness of 1.5 mm, a decrease in the radial clearance from 0.158 to 0.0395 mm led to an increase in the contact half-angle from 20 degrees to 30 degrees, and a decrease in the maximum contact pressure from 30 to 10 MPa. For zero clearance, although the contact pressure was

  13. Catalytic combustion of actual low and medium heating value gases

    NASA Technical Reports Server (NTRS)

    Bulzan, D. L.

    1982-01-01

    Catalytic combustion of both low and medium heating value gases using actual coal derived gases obtained from operating gasifiers was demonstrated. A fixed bed gasifier with a complete product gas cleanup system was operated in an air blown mode to produce low heating value gas. A fluidized bed gasifier with a water quench product gas cleanup system was operated in both an air enriched and an oxygen blown mode to produce low and medium, heating value gas. Noble metal catalytic reactors were evaluated in 12 cm flow diameter test rigs on both low and medium heating value gases. Combustion efficiencies greater than 99.5% were obtained with all coal derived gaseous fuels. The NOx emissions ranged from 0.2 to 4 g NO2 kg fuel.

  14. Motion fading is driven by perceived, not actual angular velocity.

    PubMed

    Kohler, P J; Caplovitz, G P; Hsieh, P-J; Sun, J; Tse, P U

    2010-06-01

    After prolonged viewing of a slowly drifting or rotating pattern under strict fixation, the pattern appears to slow down and then momentarily stop. Here we examine the relationship between such 'motion fading' and perceived angular velocity. Using several different dot patterns that generate emergent virtual contours, we demonstrate that whenever there is a difference in the perceived angular velocity of two patterns of dots that are in fact rotating at the same angular velocity, there is also a difference in the time to undergo motion fading for those two patterns. Conversely, whenever two patterns show no difference in perceived angular velocity, even if in fact rotating at different angular velocities, we find no difference in the time to undergo motion fading. Thus, motion fading is driven by the perceived rather than actual angular velocity of a rotating stimulus. PMID:20371254

  15. Actual leisure participation of Norwegian adolescents with Down syndrome.

    PubMed

    Dolva, Anne-Stine; Kleiven, Jo; Kollstad, Marit

    2014-02-01

    This article reports the actual participation in leisure activities by a sample of Norwegian adolescents with Down syndrome aged 14. Representing a first generation to grow up in a relatively inclusive context, they live with their families, attend mainstream schools, and are part of common community life. Leisure information was obtained in individual, structured parent interviews, and added to existing longitudinal data from a project following the sample. Generally, the leisure activity may be viewed as varying along a continuum-reaching from formal, organized, and assisted activity participation outside home, to informal, self-organized, and independent participation at home. Formal leisure activities were either organized "for all" or "adapted for disabled." The adolescents' leisure appears as active and social. However, social participation largely involved parents and family, while socializing with other adolescents mainly took place within formal activities adapted for disabled. Clearly, formal and informal activities provide rather different opportunities for social encounters and assistance. PMID:24515503

  16. Protein Residue Contacts and Prediction Methods

    PubMed Central

    Adhikari, Badri

    2016-01-01

    In the field of computational structural proteomics, contact predictions have shown new prospects of solving the longstanding problem of ab initio protein structure prediction. In the last few years, application of deep learning algorithms and availability of large protein sequence databases, combined with improvement in methods that derive contacts from multiple sequence alignments, have shown a huge increase in the precision of contact prediction. In addition, these predicted contacts have also been used to build three-dimensional models from scratch. In this chapter, we briefly discuss many elements of protein residue–residue contacts and the methods available for prediction, focusing on a state-of-the-art contact prediction tool, DNcon. Illustrating with a case study, we describe how DNcon can be used to make ab initio contact predictions for a given protein sequence and discuss how the predicted contacts may be analyzed and evaluated. PMID:27115648

  17. Ensuring Safe Use of Contact Lens Solution

    MedlinePlus

    ... For Consumers Consumer Updates Ensuring Safe Use of Contact Lens Solution Share Tweet Linkedin Pin it More ... back to top Dos and Don'ts for Contact Lens Wearers DO: Always wash your hands before ...

  18. Protein Residue Contacts and Prediction Methods.

    PubMed

    Adhikari, Badri; Cheng, Jianlin

    2016-01-01

    In the field of computational structural proteomics, contact predictions have shown new prospects of solving the longstanding problem of ab initio protein structure prediction. In the last few years, application of deep learning algorithms and availability of large protein sequence databases, combined with improvement in methods that derive contacts from multiple sequence alignments, have shown a huge increase in the precision of contact prediction. In addition, these predicted contacts have also been used to build three-dimensional models from scratch.In this chapter, we briefly discuss many elements of protein residue-residue contacts and the methods available for prediction, focusing on a state-of-the-art contact prediction tool, DNcon. Illustrating with a case study, we describe how DNcon can be used to make ab initio contact predictions for a given protein sequence and discuss how the predicted contacts may be analyzed and evaluated. PMID:27115648

  19. Rolling-Contact Spalling In Bearings

    NASA Technical Reports Server (NTRS)

    Kumar, A. M.; Kulkarni, S. M.; Bhargava, B.; Hahn, G. T.; Rubin, C. A.

    1990-01-01

    Report describes experimental and theoretical studies of effects of thermal and mechanical contact stresses and attendant plastic deformations responsible for rolling-contact spalling of the 440C-steel bearings in high-pressure-oxygen turbopump.

  20. Inferring Epidemic Contact Structure from Phylogenetic Trees

    PubMed Central

    Leventhal, Gabriel E.; Kouyos, Roger; Stadler, Tanja; von Wyl, Viktor; Yerly, Sabine; Böni, Jürg; Cellerai, Cristina; Klimkait, Thomas; Günthard, Huldrych F.; Bonhoeffer, Sebastian

    2012-01-01

    Contact structure is believed to have a large impact on epidemic spreading and consequently using networks to model such contact structure continues to gain interest in epidemiology. However, detailed knowledge of the exact contact structure underlying real epidemics is limited. Here we address the question whether the structure of the contact network leaves a detectable genetic fingerprint in the pathogen population. To this end we compare phylogenies generated by disease outbreaks in simulated populations with different types of contact networks. We find that the shape of these phylogenies strongly depends on contact structure. In particular, measures of tree imbalance allow us to quantify to what extent the contact structure underlying an epidemic deviates from a null model contact network and illustrate this in the case of random mixing. Using a phylogeny from the Swiss HIV epidemic, we show that this epidemic has a significantly more unbalanced tree than would be expected from random mixing. PMID:22412361