Combination of direct and indirect approaches for exposure assessment

We combine two major approaches currently used in human air pollution exposure assessment, the direct approach and the indirect approach. The direct approach measures exposures directly using personal monitoring. Despite its simplicity, this approach is costly and is also vulnerable to sample selection bias because it usually imposes a substantial burden on the respondents, making it difficult to recruit a representative sample of respondents. The indirect approach predicts exposures using the activity pattern model to combine activity pattern data with microenvironmental concentrations data. This approach is lower in cost and imposes less respondent burden, thus is less vulnerable to sample selection bias. However, it is vulnerable to systematic measurement error in the predicted exposures because the microenvironmental concentration data might need to be "grafted" from other data sources. The combined approach combines the two approaches to remedy the problems in each. A dual sample provides both the direct measurements of exposures based on personal monitoring and the indirect estimates based on the activity pattern model. An indirect-only sample provides additional indirect estimates. The dual sample is used to calibrate the indirect estimates to correct the systematic measurement error. If both the dual sample and the indirect-only sample are representative, the indirect estimates from the indirect-only sample is used to improve the precision for the overall estimates. If the dual sample is vulnerable to sample selection bias, the indirect-only sample is used to correct the sample selection bias. We discuss the allocation of the resources between the two subsamples and provide algorithms which can be used to determine the optimal sample allocation. The theory is illustrated with applications to the empirical data obtained from the Washington, DC, Carbon Monoxide (CO) Study.     

A highly compact packaging concept for ultrasound transducer arrays embedded in neurosurgical needles

Microsystem Technologies - State-of-the-art neurosurgery intervention relies heavily on information from tissue imaging taken at a pre-operative stage. However, the data retrieved prior to...     

Identification of PLCgamma-dependent and -independent events during fertilization of sea urchin eggs

At fertilization, sea urchin eggs undergo a series of activation events, including a Ca2+ action potential, Ca2+ release from the endoplasmic reticulum, an increase in intracellular pH, sperm pronuclear formation, MAP kinase dephosphorylation, and DNA synthesis. To examine which of these events might be initiated by activation of phospholipase Cgamma (PLCgamma), which produces the second messengers inositol trisphosphate (IP3) and diacylglycerol, we used recombinant SH2 domains of PLCgamma as specific inhibitors. Sea urchin eggs were co-injected with a GST fusion protein composed of the two tandem SH2 domains of bovine PLCgamma and (1) Ca2+ green dextran to monitor intracellular free Ca2+, (2) BCECF dextran to monitor intracellular pH, (3) Oregon Green dUTP to monitor DNA synthesis, or (4) fluorescein 70-kDa dextran to monitor nuclear envelope formation. Microinjection of the tandem SH2 domains of PLCgamma produced a concentration-dependent inhibition of Ca2+ release and also inhibited cortical granule exocytosis, cytoplasmic alkalinization, MAP kinase dephosphorylation, DNA synthesis, and cleavage after fertilization. However, the Ca2+ action potential, sperm entry, and sperm pronuclear formation were not prevented by injection of the PLCgammaSH2 domain protein. Microinjection of a control protein, the tandem SH2 domains of the phosphatase SHP2, had no effect on Ca2+ release, cortical granule exocytosis, DNA synthesis, or cleavage. Specificity of the inhibitory action of the PLCgammaSH2 domains was further indicated by the finding that microinjection of PLCgammaSH2 domains that had been point mutated at a critical arginine did not inhibit Ca release at fertilization. Additionally, Ca2+ release in response to microinjection of IP3, cholera toxin, cADP ribose, or cGMP was not inhibited by the PLCgammaSH2 fusion protein. These results indicate that PLCgamma plays a key role in several fertilization events in sea urchin eggs, including Ca2+ release and DNA synthesis, but that the action potential, sperm entry, and male pronuclear formation can occur in the absence of PLCgamma activation or Ca2+ increase.     

Use of a laparoscopic insufflation port for ileal conduit endoscopy

We present an effective and simple technique for performing endoscopy of an ileal conduit. With a laparoscopic insufflation port in the stoma, a flexible cystoscope or ureteroscope can be inserted. The one-way valve of the port prevents leakage of irrigation fluid and allows the conduit to distend for optimal visualization. This technique is particularly useful when access to the upper urinary tracts is needed.     

Determinant assembled stowage bins—a case study

Most commercial aircraft interior stowage bins are assembled using jigs. These assembly jigs are built to strict tolerances to ensure that the assemblies created in them will perform properly. Over the past decade, commercial aircraft structures assembly has been in transition from a method of assembly jig location to a method of part to part indexing, also known as Determinant Assembly. This method is now being investigated for accurate location of composite sandwich panels and metal attachments for commercial aircraft interiors. A background on Determinant Assembly (DA) as it has developed in structures is introduced. Several methods of coordinating composite sandwich panels to metal parts are discussed. Data that substantiates the use of these methods to maintain the prescribed tolerances is presented graphically. The results of building prototype parts using these techniques are presented. The process capability for DA assembled stowage bins is predicted using Variation Simulation Analysis, and those predictions are compared to results obtained with the current assembly jig method.     

Fabrication of niobium doped Pb（Zr, Ti）O3 fibers by viscous polymer processing

A technique based on viscous polymer processing （VPP） was described, which can produce high ceramic content green fibers. PZT-5 ceramic powders were ball milled to get high dispersibility. The slurry prepared for VPP was a composition of PZT-5 powder, PVA binder and glycerin. High ceramic content PZT-5 fibers were extruded with the slurry. The results show that the ceramic powders have fine mean particle size of 0.54 pan, high specific surface area of 3.55 m^2/g and zeta potential of 8.81 mV after 16 h milling. The fibers sintered at 1 280 ℃ for 4 h have pure perovskite structure and grains of 2-5 μm in size, with little pores or cracks. The ultimate tensile strength of sintered fibers is up to 13.84 MPa compared with 2.88 MPa of green fibers. The remnant polarization （Pr） and coercive field （Ec） of the fibers are 50.65 μC/cm^2 and 2.45 kV/mm, respectively. This fiber can withstand an electric field of 9 kV/mm higher than the ceramic （5 kV/mm）, which shows high directional and compact qualities.     

Adenoviral-mediated delivery of the herpes simplex virus thymidine kinase gene selectively sensitizes human ovarian carcinoma cells to ganciclovir

One strategy used for gene therapy of cancer is molecular chemotherapy. This approach is based on selective expression of an encoded toxin in cancer cells to achieve their eradication. One potential advantage of this strategy derives from a phenomenon, termed the bystander effect, whereby only a fraction of cells needs to be transduced to eradicate a tumor population. Despite the theoretical advantages of this phenomenon, it has only been described in a few cellular targets. Therefore, we undertook strategies to develop a molecular chemotherapy approach for ovarian carcinoma utilizing the herpes simplex virus thymidine kinase (HSV-TK) gene. Initially, we established that human ovarian carcinoma cell lines could be transduced at high efficiency with adenoviral vectors encoding reporter genes. We next determined that the human ovarian cell line SKOV3 could exhibit bystander killing by stably transducing it to express HSV-TK and performing cell mixing experiments with varying percentages of HSV-TK-expressing and HSV-TK-nonexpressing cells. Based on these findings, we constructed a recombinant adenovirus encoding HSV-TK and utilized it to induce human ovarian carcinoma cell lines to the sensitizing effects of ganciclovir. In addition, primary cultures of ovarian carcinoma cells were found to be highly transducible with recombinant adenoviral vectors and could be induced to the sensitizing effects of ganciclovir after induction of HSV-TK expression by the adenoviral vector. These studies indicate that molecular chemotherapy using a recombinant adenoviral vector expressing HSV-TK may provide a rational strategy for human ovarian carcinoma.     

A carcinoembryonic antigen polynucleotide vaccine for human clinical use

Congenital cataract, type Volkmann (McKusick no 115665, gene symbol CCV) is an autosomal dominant eye disease. The disease is characterized by a progressive, central and zonular cataract, with opacities both in the embryonic, fetal and juvenile nucleus and around the anterior and posterior Y-suture. We examined blood samples from 91 members of a Danish pedigree comprising 426 members, by using highly informative short tandem repeat polymorphisms and found the closest linkage of the disease gene (CCV) to a (CA)n dinucleotide repeat polymorphism at locus D1S243 (Zmax = 14.04 at theta M = 0.025 theta F = 0.000), at a penetrance of 0.90. Using two additional chromosome 1 markers, we were able to map the CCV gene in the sequence 1pter-(CCV, D1S243)-D1S468-D1S214. The (enolase 1) gene has been mapped to this area; however, a mutation described in this gene did not give eye disease.