Dichotomy in the T-linear resistivity in hole-doped cuprates

From analysis of the in-plane resistivity ρ(ab)(T) of La(2-x)Sr(x)CuO(4), we show that normal state transport in overdoped cuprates can be delineated into two regimes in which the electrical resistivity varies approximately linearly with temperature. In the low-temperature limit, the T-linear resistivity extends over a very wide doping range, in marked contrast to expectations from conventional quantum critical scenarios. The coefficient of this T-linear resistivity scales with the superconducting transition temperature T(c), implying that the interaction causing this anomalous scattering is also associated with the superconducting pairing mechanism. At high temperatures, the coefficient of the T-linear resistivity is essentially doping independent beyond a critical doping p(crit)=0.19 at which the ratio of the two coefficients is maximal. Taking our cue from earlier thermodynamic and photoemission measurements, we conclude that the opening of the normal-state pseudogap at p(crit) is driven by the loss of coherence of anti-nodal quasi-particles at low temperatures.     

Do cosmetics enhance female Caucasian facial attractiveness?

This study sought to investigate whether cosmetics do improve female facial attractiveness, and to determine whether the contribution of different cosmetic products are separable, or whether they function synergistically to enhance female beauty. Ten volunteers were made up by a beautician under five cosmetics conditions: (i) no make-up; (ii) foundation only; (iii) eye make-up only; (iv) lip make-up only; and (v) full facial make-up. Male and female participants were asked to view the 10 sets of five photographs, and rank each set from most attractive to least attractive. As predicted, faces with full make-up were judged more attractive than the same faces with no make-up. Sex differences within the results were also apparent. Women judged eye make-up as contributing most to the attractiveness. Men rated eye make-up and foundation as having a significant impact on the attractiveness of a full facial makeover. Surprisingly, lipstick did not appear to contribute to attractiveness independently.     

The registered dietitian in primary care: the Hamilton experience.

The Hamilton Health Service Organization Nutrition Program integrates nine registered dietitians (RDs) into the offices of 80 family physicians (FPs) at 50 sites in Hamilton, Ontario. The program is based on a shared care model, in which FPs and RDs work collaboratively to provide nutrition services aimed at prevention, treatment, and management of nutrition-related problems. In addition to their clinical role, dietitians in the program are involved in health promotion, disease prevention and early intervention strategies, interdisciplinary collaboration, building links with community services, and research. The RDs' specialized knowledge, skills, and experience allow them to provide a wide range of services that complement and augment those of the FP. This model is consistent with Canadian health care reform recommendations and offers significant benefits for both health care providers and consumers.     

Water distribution measurement for a PEMFC through neutron radiography

Neutron radiography has been used for in situ and non-destructive visualization and measurement technique for liquid water in a working proton exchange membrane fuel cell (PEMFC). In an attempt to differentiate water distribution in the anode side from that in the cathode side, a specially designed cell was machined and used for the experiment. The major difference between our design and traditional flow field design is the fact the anode channels and cathode channels were shifted by a channel width, so that the anode and cathode channels do not overlap in the majority of the active areas.

The neutron radiography experiments were performed at selected relative humidities, and stoichiometry values of cathode inlet. At each operating condition, the water distribution in anode/cathode gas diffusion layers (GDLs) was obtained. Image processing with four different spatial masks was applied to those images to differentiate liquid water in four different types of areas. Results indicate that the reactant gas relative humidity and stoichiometry significantly influence current density distribution and water distribution.     

A collaborative approach to standards, practices. Setting the stage for continuous quality improvement

In retrospect, the most important thing we did was work together. We analyzed, refined, and validated our philosophical approach to patient care. We provided an information data base that is readily available for on-the-job reference and serves as a starting point for CQI activities. The very act of joint documentation of practices encourages open discussions about improvements to patient care. One physician states, We know that flaws in the process through which we produce care are everywhere--waste, duplication of effort, unnecessary complexity, and unpredictability . . . I believe that modern total quality management offers enormous hope to a medical care field that is rather desperate. . . . Collaborative practice and CQI activities are one hope. The scope of what nurses and physicians traditionally consider when discussing standards and practices must widen. We should no longer look only at patient care. We must simultaneously focus on how the management of total systems influences quality care for all patients. The CQI process, a proactive method, requires an accurate data base of information that is easily retrieved when looking for systems and individual patient care improvements. Our Computerized Collaborative Standards and Practices Manual is the reservoir for documenting practice plans developed and approved by all the disciplines involved. The process described here began with two closely knit operating room disciplines; this framework, however, offers the potential for expansion into a hospital-wide system of information organization and use.     

The characterization of fatigue crack growth behaviour by constant ΔK control testing

Essential to the assessment of the fatigue integrity of critical components is the prediction of their crack propagation lives. This requires the effective and efficient characterization of the fatigue crack growth behaviour of the material when using a small number of specimens. A test facility, able to control the range of applied load (Δ P ) and range of stress intensity factor (Δ K ), has been used to determine the fatigue crack growth rates in corner notched specimens of Udimet 720 for stress ratios of 0.5, 0.1 and −1.0. Initially, the results were analysed in terms of the three-point secant data reduction method. Subsequently, the benefits to be gained by the use of alternative methods involving regression analysis have been examined. The effectiveness of the procedures has been assessed in terms of the extent to which they reduce the width of the scatter band representing the fatigue crack growth behaviour and the accuracy with which the experimental observed fatigue lives are predicted. On this basis, the results from the Δ K controlled tests were superior to those obtained under Δ P control, when analysed by similar data reduction methods. In addition, the results from Δ K tests were improved when the secant method was replaced by a linear regression method, which allowed the sample interval to be reduced and more levels of constant Δ K to be examined in a single specimen.     

Voltage instability in a simulated fuel cell stack correlated to cathode water accumulation

Single fuel cells running independently are often used for fundamental studies of water transport. It is also necessary to assess the dynamic behavior of fuel cell stacks comprised of multiple cells arranged in series, thus providing many paths for flow of reactant hydrogen on the anode and air (or pure oxygen) on the cathode. In the current work, the flow behavior of a fuel cell stack is simulated by using a single-cell test fixture coupled with a bypass flow loop for the cathode flow. This bypass simulates the presence of additional cells in a stack and provides an alternate path for airflow, thus avoiding forced convective purging of cathode flow channels. Liquid water accumulation in the cathode is shown to occur in two modes; initially nearly all the product water is retained in the gas diffusion layer until a critical saturation fraction is reached and then water accumulation in the flow channels begins. Flow redistribution and fuel cell performance loss result from channel slug formation. The application of in-situ neutron radiography affords a transient correlation of performance loss to liquid water accumulation. The current results identify a mechanism whereby depleted cathode flow on a single cell leads to performance loss, which can ultimately cause an operating proton exchange membrane fuel cell stack to fail.     

Osteocyte pericellular and perilacunar matrices as markers of bone–implant mechanical integrity

To develop durable bone healing strategies through improved control of bone repair, it is of critical importance to understand the mechanisms of bone mechanical integrity when in contact with biomaterials and implants. Bone mechanical integrity is defined here as the adaptation of structural properties of remodeled bone in regard to an applied mechanical loading. Accordingly, the authors present why future investigations in bone repair and regeneration should emphasize on the matrix surrounding the osteocytes. Osteocytes are mechanosensitive cells considered as the orchestrators of bone remodeling, which is the biological process involved in bone homeostasis. These bone cells are trapped in an interconnected porous network, the lacunocanalicular network, which is embedded in a bone mineralized extracellular matrix. As a consequence of an applied mechanical loading, the bone deformation results in the deformation of this lacunocanalicular network inducing a shift in interstitial fluid pressure and velocity, thus resulting in osteocyte stimulation. The material environment surrounding each osteocyte, the so called perilacunar and pericellular matrices properties, define its mechanosensitivity. While this mechanical stimulation pathway is well known, the laws used to predict bone remodeling are based on strains developing at a tissue scale, suggesting that these strains are related to the shift in fluid pressure and velocity at the lacunocanalicular scale. While this relationship has been validated through observation in healthy bone, the fluid behavior at the bone-implant interface is more complex. The presence of the implant modifies fluid behavior, so that for the same strain at a tissue scale, the shift in fluid pressure and velocity will be different than in a healthy bone tissue. In that context, new markers for bone mechanical integrity, considering fluid behavior, have to be defined. The viewpoint exposed by the authors indicates that the properties of the pericellular and the perilacunar matrices have to be systematically investigated and used as structural markers of fluid behavior in the course of bone biomaterial development.