Performance of Glued-Laminated Timbers with FRP Shear and Flexural Reinforcement

Glued-laminated wood beams (glulams) have low allowable shear stresses relative to competitive engineering wood products such as parallel strand lumber and laminated veneer lumber. For heavily loaded applications such as garage door headers, the lower shear allowable stresses typically necessitate the use of larger glulam members relative to other engineered lumber. This paper reports on experimental research aimed at increasing the shear capacity of glulams. To increase the shear strength, a series of fiber-reinforced polymeric (FRP) pins are inserted into holes drilled transversely across the plies of the glulam. These pins are epoxy-bonded into place after the glulam has been produced. The test results show that the shear strength scatter in the pinned set of glulams is significantly reduced as compared to the unpinned specimens. Two- and three-parameter Weibull estimates of the service-level allowables increases between 40% and 100% for specimen sets reinforced by the FRP pins. The transverse reinforcing scheme also shows promise for aiding in engagement of composite flexural reinforcement plies into the laminate stack. Previous research has shown that the bonding between wood and FRP plies has potential long-term durability problems. Therefore, the pinning technology reported on in this work shows promise for providing a means for direct engagement (through bearing of the pins) of the FRP plies to the wood plies. This behavior has been demonstrated though the testing of larger-scale specimens with both transverse shear reinforcements and longitudinal FRP plies. The reinforcing strategies show potential structural and economic advantages, especially when the FRP is coupled with low-grade, low-value finger-jointed lumber.     

RGS3 inhibits G protein-mediated signaling via translocation to the membrane and binding to Galpha11

In the present study, we investigated the function and the mechanism of action of RGS3, a member of a family of proteins called regulators of G protein signaling (RGS). Polyclonal antibodies against RGS3 were produced and characterized. An 80-kDa protein was identified as RGS3 by immunoprecipitation and immunoblotting with anti-RGS3 antibodies in a human mesangial cell line (HMC) stably transfected with RGS3 cDNA. Coimmunoprecipitation experiments in RGS3-overexpressing cell lysates revealed that RGS3 bound to aluminum fluoride-activated Galpha11 and to a lesser extent to Galphai3 and that this binding was mediated by the RGS domain of RGS3. A role of RGS3 in postreceptor signaling was demonstrated by decreased calcium responses and mitogen-activated protein (MAP) kinase activity induced by endothelin-1 in HMC stably overexpressing RGS3. Moreover, depletion of endogenous RGS3 by transfection of antisense RGS3 cDNA in NIH 3T3 cells resulted in enhanced MAP kinase activation induced by endothelin-1. The study of intracellular distribution of RGS3 indicated its unique cytosolic localization. Activation of G proteins by AlF4-, NaF, or endothelin-1 resulted in redistribution of RGS3 from cytosol to the plasma membrane as determined by Western blotting of the cytosolic and particulate fractions with RGS3 antiserum as well as by immunofluorescence microscopy. Agonist-induced translocation of RGS3 occurred by a dual mechanism involving both C-terminal (RGS domain) and N-terminal regions of RGS3. Thus, coexpression of RGS3 with a constitutively active mutant of Galpha11 (Galpha11-QL) resulted in the binding of RGS3, but not of its N-terminal fragment, to the membrane fraction and in its interaction with Galpha11-QL in vitro without any stimuli. However, both full-length RGS3 and its N-terminal domain translocated to the plasma membrane upon stimulation of intact cells with endothelin-1 as assayed by immunofluorescence microscopy. The effect of endothelin-1 was also mimicked by calcium ionophore A23187, suggesting the importance of Ca2+ in the mechanism of redistribution of RGS3. These data indicate that RGS3 inhibits G protein-coupled receptor signaling by a complex mechanism involving its translocation to the membrane in addition to its established function as a GTPase-activating protein.     

The effect of halothane on the recirculatory pharmacokinetics of physiologic markers

BACKGROUND: The cardiovascular effects of halothane are well recognized, but little is known of how this affects drug distribution. The effect of halothane anesthesia on physiologic factors that affect drug disposition from the moment of injection was investigated. METHODS: The dispositions of markers of intravascular space and blood flow (indocyanine green), extracellular space and free water diffusion (inulin), and total body water and tissue perfusion (antipyrine) were determined in four purpose-bred coonhounds. The dogs were studied while awake and while anesthetized with 1%, 1.5%, and 2% halothane in a randomized order determined by a repeated measures Latin square experimental design. Marker dispositions were described by recirculatory pharmacokinetic models based on frequent early and less frequent later arterial blood samples. These models characterize the role of cardiac output and its distribution on drug disposition. RESULTS: Halothane caused a significant and dose-dependent decrease in cardiac output. The disposition of antipyrine was most profoundly affected by halothane anesthesia, which increased both nondistributive intercompartmental clearance and volume while decreasing fast and slow tissue clearances and elimination clearance in a halothane dose-dependent manner. CONCLUSIONS: Halothane-induced changes in blood flow to the compartments of the antipyrine recirculatory model were not proportional to changes in cardiac output. Halothane anesthesia significantly increased (to more than double) the area under the drug concentration versus time curve due to an increase in the apparent peripheral blood flow not involved in drug distribution, despite a dose-dependent cardiac output decrease. Recirculatory pharmacokinetic models include the best aspects of traditional compartmental and physiologic pharmacokinetic models while offering advantages over both.     

Image correlation spectroscopy. II. Optimization for ultrasensitive detection of preexisting platelet-derived growth factor-beta receptor oligomers on intact cells

Previously we introduced image correlation spectroscopy (ICS) as an imaging analog of fluorescence correlation spectroscopy (FCS). Implementation of ICS with image collection via a standard fluorescence confocal microscope and computer-based autocorrelation analysis was shown to facilitate measurements of absolute number densities and determination of changes in aggregation state for fluorescently labeled macromolecules. In the present work we illustrate how to use ICS to quantify the aggregation state of immunolabeled plasma membrane receptors in an intact cellular milieu, taking into account background fluorescence. We introduce methods that enable us to completely remove white noise contributions from autocorrelation measurements for individual images and illustrate how to perform background corrections for autofluorescence and nonspecific fluorescence on cell population means obtained via ICS. The utilization of photon counting confocal imaging with ICS analysis in combination with the background correction techniques outlined enabled us to achieve very low detection limits with standard immunolabeling methods on normal, nontransformed human fibroblasts (AG1523) expressing relatively low numbers of platelet-derived growth factor-beta (PDGF-beta) receptors. Specifically, we determined that the PDGF-beta receptors were preaggregated as tetramers on average with a mean surface density of 2.3 clusters micrometer(-2) after immunolabeling at 4 degreesC. These measurements, which show preclustering of PDGF-beta receptors on the surface of normal human fibroblasts, contradict a fundamental assumption of the ligand-induced dimerization model for signal transduction and provide support for an alternative model that posits signal transduction from within preexisting receptor aggregates.     

Screening for detecting twin pregnancy

Estimation of HPL during the twenty-ninths to the thirtieth week of pregnancy is a simple and safe method for detecting twins. Nine out of 10 pregnant women have a value below 5.0 mug per milliliter, which excludes the suspicion of twins. In the remaining women with higher values the diagnosis can be confirmed or excluded by ultrasound or x-ray.     

近程地对地战术导弹总体/发动机一体化优化设计

地对地战术导弹总体/发动机一体化优化设计是把飞行器和发动机作为一个系统,以系統性能最佳作为目标值来优选飞行器总体和发动机的设计参数。针对近程地对地战术导弹建立了最优控制过程模型及一体化的全系統模型。着重分析了一体化模型建立,融内外弹道为一体,各级同时优化,并应用庞特里雅金(Pontryagin)最小值原理和非线性多目标规划理论进行了求解。