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Simple Concept (simple + concept)
Selected AbstractsAdvancement Flaps: A Basic Theme with Many VariationsDERMATOLOGIC SURGERY, Issue 2005Ravi Krishnan MD Background. The advancement flap involves the linear advancement of tissue in one direction. Despite its straightforwardness and simple concept, it can be used to close a variety of defects, ranging from small defects on the scalp or extremities to large, complicated defects involving cosmetic units on the face. Objectives. To provide a basic and useful review for the indications, advantages, disadvantages, and techniques for the use of advancement flaps in the reconstruction of defects in dermatologic surgery. Materials and Methods. We performed a literature search for articles discussing advancement flaps and compiled a brief review of our findings. Results. The movement of the advancement flap must be balanced by the blood supply of the flap. The excision of Burow's triangles along various aspects of the advancement flap can increase movement and improve cosmesis of the flap. The types of advancement flaps discussed include the single advancement flap, double advancement flap, A-T flap (O-T flap), Burow's triangle flap (Burow's wedge flap), crescenteric advancement flap, island pedicle flap (V-Y flap), helical rim advancement flap, and facelift flap. Conclusion. Advancement flaps are versatile and useful basic flaps for repairing defects. [source] Evapotranspiration covers: An innovative approach to remediate and close contaminated sitesREMEDIATION, Issue 1 2003Kelly L. Madalinski A new, cost-effective option for the remediation and final closure of contaminated landfill sites gaining interest among environmental professionals is the evapotranspiration (ET) cover. Unlike current covers that use hydraulic barriers to prevent water from reaching the waste, ET covers rely on the simple concept of using water balance components to meet this goal. Depending on site conditions and other factors, ET covers may be less costly to construct, while still offering performance equivalent to conventional covers. While ET covers are being proposed, tested, or installed at a number of contaminated sites, field performance data remain limited. To address the need for more information, the U.S. Environmental Protection Agency (EPA) has been conducting several efforts to make available more information about this promising alternative solution. This article summarizes these efforts and provides information on the current status of using ET covers at contaminated sites. © 2003 Wiley Periodicals, Inc. [source] Overcoming Kinetic Limitations of Electron Injection in the Dye Solar Cell via Coadsorption and FRETCHEMPHYSCHEM, Issue 5 2008Conrad Siegers Abstract A new, extremely simple concept for the use of energy transfer as a means to the enhancement of light absorption and current generation in the dye solar cell (DSC) is presented. This model study is based upon a carboxy-functionalized 4-aminonaphthalimide dye (carboxy-fluorol) as donor, and (NBu4)2[Ru(dcbpy)2(NCS)2] (N719) as acceptor chromophores. A set of three different devices is assembled containing either exclusively carboxy-fluorol or N719, or a mixture of both. This set of transparent devices is characterized via IV-measurements under AM1.5G and monochromatic illumination and their light-harvesting and external quantum efficiencies (LHE and EQE, respectively) are determined as well. It is shown that the device containing only the donor chromophore has a marginal power conversion efficiency, thus indicating that carboxy-fluorol is a poor sensitizer for the DSC. Cyclovoltametric measurements show that the poor sensitization ability arises from the kinetic inhibition of electron injection into the TiO2 conduction band. Comparing the spectral properties of the DSCs assembled presently, however, demonstrates that light absorbed by carboxy-fluorol is almost quantitatively contributing to the photocurrent if N719 is present as an additional sensitizer. In this case, N719 acts as a catalyst for the sensitization of TiO2 by carboxy-fluorol in addition to being a photosensitizer. Evaluation of the maximum output power under blue illumination shows that the introduction of an energy-donor moiety via coadsorption, leads to a significant increase in the monochromatic maximum output power. This result demonstrates that energy transfer between coadsorbed chromophores could be useful for the generation of current in dye-sensitized solar cells. [source] The effects of diel changes in circulation and mixing on the longitudinal distribution of phytoplankton in a canyon-shaped Mediterranean reservoirFRESHWATER BIOLOGY, Issue 9 2010JAVIER VIDAL Summary 1. The near-surface distribution of phytoplankton cells along the thalweg of a canyon-shaped reservoir (El Gergal, southern Spain) during two surveys is described and interpreted as the result of time-varying large-scale circulation patterns, vertical mixing processes and the physiological capacity of algal cells to regulate its position in the water column. 2. Vertical gradients of chlorophyll-a concentration developed in the water column during the day but disappeared at night, as a result of the shoaling and deepening of the diurnal mixed layer (dml). The changes in the depth of the dml are largely controlled in El Gergal by convectively driven mixing processes. The longitudinal circulation changes, in turn, as a result of weak and diurnal land-sea breezes. The distribution of algal cells was patchy at all times but did not change during any of the surveys. 3. An expression is proposed to estimate time scales for the development of horizontal patchiness TP based on simple concepts of transport. It is shown that TP is in the order of a week, indicating that horizontal patchiness does not respond immediately to hourly changes in the controlling factors. The magnitude of TP, though, depends on how the vertical distribution of chlorophyll-a and longitudinal currents change on subdiurnal time scales. In particular, TP is sensitive to the lag existing between the momentum and heat fluxes through the free surface, driving circulation and vertical mixing. [source] Viral escape mechanisms , escapology taught by virusesINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 5 2001Michaela Lucas Viruses have ,studied' immunology over millions of years of coevolution with their hosts. During this ongoing education they have developed countless mechanisms to escape from the host's immune system. To illustrate the most common strategies of viral immune escape we have focused on two murine models of persistent infection, lymphocytic choriomeningitis virus (LCMV) and murine cytomegalovirus (MCMV).LCMV is a fast replicating small RNA virus with a genome prone to mutations. Therefore, LCMV escapes from the immune system mainly by two strategies: ,speed' and ,shape change'. At the opposite extreme, MCMV is a large, complex DNA virus with a more rigid genome and thus the strategies used by LCMV are no option. However, MCMV has the coding capacity for additional genes which interfere specifically with the immune response of the host. These escape strategies have been described as ,camouflage' and ,sabotage'. Using these simple concepts we describe the spectrum of viral escapology, giving credit not only to the researchers who uncovered this fascinating area of immunology but also to the viruses themselves, who still have a few lessons to teach. [source] | ||||||||||