191 research outputs found

    Development of Discourse and Criteria in Green Building

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    The development of sustainable design rating systems and forward-thinking case studies create an increasingly holistic approach to green building that reflects and drives broader changes in sustainability discourse. Introduction of LEED by the U.S. Green Building Council alongside the Adam Joseph Lewis Center at Oberlin College transformed loosely defined notions of environmentally responsible and sustainable architecture into a tangible, comprehensive definition of green building. New rating systems in the late 2000s, Living Building Challenge and SITES, expanded green building to strengthen quantitative benchmarks, introduce qualitative standards such as biophilic design, and provide increased focus on site sustainability. Case studies at the time, such as Kroon Hall at Yale University, draw influence from new rating systems and illustrate a full-scale model of sustainable design. Living Building Challenge and other International Living Future Institute certifications shifted the conversation around green building toward decarbonization and influenced newer projects such as the Robert Redford Conservancy at Pitzer College to create buildings that will be responsive to a changing climate. Analysis of recent updates to certification systems and modern green building projects indicates a future of green buildings primarily based in decarbonization and resilience, as a reaction to uncertain yet inevitable effects of climate change in the future

    Histologic Comparison of Argon and Tunable Dye Lasers in the Treatment of Tattoos

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    Cosmetic benefit from laser therapy of tattoos may simply be the result of thermal injury and host reparative response which remove pigment by a “slough and bury” mechanism. Tattoo pigment of 4 colors (black, white, red, and blue) was introduced into the skin of guinea pigs and studied histologically at 48 h, 7 days, 4 and 6 weeks, and 3 months. Tattoos of each color were treated with argon laser (488 and 514 nm) and tunable dye laser at 3 different wavelengths (505, 577, and 690 nm). Treated tattoos were biopsied immediately and at 48 h, 7 days, and 3 months. Selective laser absorption by the tattoo pigment was suggested by pigment-related differences in threshold doses for histologic damage. Clinical clearing of tattoo pigment correlated well with the extent of immediate epidermal and dermal necrosis and was as well associated histologically with the deposition of parallel bands of collagen fibers (i.e., scar) between the residual pigment and the overlying epidermis. “Lightening” of tattoos probably depends more on widespread necrosis, subsequent tissue sloughing, and resultant dermal fibrosis than on specific changes in tattoo pigment chemistry, morphology, physical properties, or handling by macrophages

    Well-Water Consumption and Parkinson’s Disease in Rural California

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    IntroductionInvestigators have hypothesized that consuming pesticide-contaminated well water plays a role in Parkinson's disease (PD), and several previous epidemiologic studies support this hypothesis.ObjectivesWe investigated whether consuming water from private wells located in areas with documented historical pesticide use was associated with an increased risk of PD.MethodsWe employed a geographic information system (GIS)-based model to estimate potential well-water contamination from agricultural pesticides among 368 cases and 341 population controls enrolled in the Parkinson's Environment and Genes Study (PEG). We separately examined 6 pesticides (diazinon, chlorpyrifos, propargite, paraquat, dimethoate, and methomyl) from among 26 chemicals selected for their potential to pollute groundwater or for their interest in PD, and because at least 10% of our population was exposed to them.ResultsCases were more likely to have consumed private well water and to have consumed it on average 4.3 years longer than controls (p = 0.02). High levels of possible well-water contamination with methomyl [odds ratio (OR) = 1.67; 95% confidence interval (CI), 1.00-2.78]), chlorpyrifos (OR = 1.87; 95% CI, 1.05-3.31), and propargite (OR = 1.92; 95% CI, 1.15-3.20) resulted in approximately 70-90% increases in relative risk of PD. Adjusting for ambient pesticide exposures only slightly attenuated these increases. Exposure to a higher number of water-soluble pesticides and organophosphate pesticides also increased the relative risk of PD.ConclusionOur study, the first to use agricultural pesticide application records, adds evidence that consuming well water presumably contaminated with pesticides may play a role in the etiology of PD

    Anomalous versus slowed-down Brownian diffusion in the ligand-binding equilibrium

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    Measurements of protein motion in living cells and membranes consistently report transient anomalous diffusion (subdiffusion) which converges back to a Brownian motion with reduced diffusion coefficient at long times, after the anomalous diffusion regime. Therefore, slowed-down Brownian motion could be considered the macroscopic limit of transient anomalous diffusion. On the other hand, membranes are also heterogeneous media in which Brownian motion may be locally slowed-down due to variations in lipid composition. Here, we investigate whether both situations lead to a similar behavior for the reversible ligand-binding reaction in 2d. We compare the (long-time) equilibrium properties obtained with transient anomalous diffusion due to obstacle hindrance or power-law distributed residence times (continuous-time random walks) to those obtained with space-dependent slowed-down Brownian motion. Using theoretical arguments and Monte-Carlo simulations, we show that those three scenarios have distinctive effects on the apparent affinity of the reaction. While continuous-time random walks decrease the apparent affinity of the reaction, locally slowed-down Brownian motion and local hinderance by obstacles both improve it. However, only in the case of slowed-down Brownian motion, the affinity is maximal when the slowdown is restricted to a subregion of the available space. Hence, even at long times (equilibrium), these processes are different and exhibit irreconcilable behaviors when the area fraction of reduced mobility changes.Comment: Biophysical Journal (2013

    Quantitative analysis of single particle trajectories: mean maximal excursion method

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    An increasing number of experimental studies employ single particle tracking to probe the physical environment in complex systems. We here propose and discuss new methods to analyze the time series of the particle traces, in particular, for subdiffusion phenomena. We discuss the statistical properties of mean maximal excursions, i.e., the maximal distance covered by a test particle up to time t. Compared to traditional methods focusing on the mean squared displacement we show that the mean maximal excursion analysis performs better in the determination of the anomalous diffusion exponent. We also demonstrate that combination of regular moments with moments of the mean maximal excursion method provides additional criteria to determine the exact physical nature of the underlying stochastic subdiffusion processes. We put the methods to test using experimental data as well as simulated time series from different models for normal and anomalous dynamics, such as diffusion on fractals, continuous time random walks, and fractional Brownian motion.Comment: 10 pages, 7 figures, 2 tables. NB: Supplementary material may be found in the downloadable source file

    A Potent Glucose-Platinum Conjugate Exploits Glucose Transporters and Preferentially Accumulates in Cancer Cells

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    Three rationally designed glucose–platinum conjugates (Glc–Pts) were synthesized and their biological activities evaluated. The Glc–Pts, 1–3, exhibit high levels of cytotoxicity toward a panel of cancer cells. The subcellular target and cellular uptake mechanism of the Glc–Pts were elucidated. For uptake into cells, Glc–Pt 1 exploits both glucose and organic cation transporters, both widely overexpressed in cancer. Compound 1 preferentially accumulates in and annihilates cancer, compared to normal epithelial, cells in vitro.National Cancer Institute (U.S.) (CA034992
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