5,955 research outputs found

    The Prevalence of Carbon-13 in Respiratory Carbon Dioxide As an Indicator of the Type of Endogenous Substrate. The change from lipid to carbohydrate during the respiratory rise in potato slices

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    Isotope discrimination is a common feature of biosynthesis in nature, with the result that different classes of carbon compounds frequently display different 13C/12C ratios. The 13C/12C ratio of lipid in potato tuber tissue is considerably lower than that for starch or protein. We have collected respiratory CO2 from potato discs in successive periods through 24 hr from the time of cutting—an interval in which the respiration rate rises 3–5-fold. The 13C/12C ratio of the evolved CO2 was determined for each period, and compared with the 13C/12C ratios of the major tissue metabolites. In the first hours the carbon isotope ratio of the CO2 matches that of lipid. With time, the ratio approaches that typical of starch or protein. An estimation has been made of the contribution of lipid and carbohydrate to the total respiration at each juncture. In connection with additional observations, it was deduced that the basal, or initial, respiration represents lipid metabolism —- possibly the alpha-oxidation of long chain fatty acids -— while the developed repiration represents conventional tricarboxylic acid cycle oxidation of the products of carbohydrate glycolysis. The true isotopic composition of the respiratory CO2 may be obscured by fractionation attending the refixation of CO2 during respiration, and by CO2 arising from dissolved CO2 and bicarbonate preexisting in the tuber. Means are described for coping with both pitfalls

    Pulse transit time: a new approach to haemodynamic monitoring in obstetric spinal anaesthesia

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    Part of the Portfolio Thesis by Geoffrey H. Sharwood-Smith: The inferior vena caval compression theory of hypotension in obstetric spinal anaesthesia: studies in normal and preeclamptic pregnancy, a literature review and revision of fundamental concepts, available at http://hdl.handle.net/10023/1815Original abstract presented at the Obstetric Anaesthetisits' Association congress 2002, Nottingham, 9-10 May.Postprin

    Pulse transit time confirms altered response to spinal anaesthesia in pregnancy induced hypertension

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    Poster presented at the International Society for the Study of Hypertension in Pregnancy (ISSHP)Congress, Toronto 2002.Part of the Portfolio Thesis by Geoffrey H. Sharwood-Smith: The inferior vena caval compression theory of hypotension in obstetric spinal anaesthesia: studies in normal and preeclamptic pregnancy, a literature review and revision of fundamental concepts, available at http://hdl.handle.net/10023/1815Postprin

    A Robust Numerical Method for Integration of Point-Vortex Trajectories in Two Dimensions

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    The venerable 2D point-vortex model plays an important role as a simplified version of many disparate physical systems, including superfluids, Bose-Einstein condensates, certain plasma configurations, and inviscid turbulence. This system is also a veritable mathematical playground, touching upon many different disciplines from topology to dynamic systems theory. Point-vortex dynamics are described by a relatively simple system of nonlinear ODEs which can easily be integrated numerically using an appropriate adaptive time stepping method. As the separation between a pair of vortices relative to all other inter-vortex length scales decreases, however, the computational time required diverges. Accuracy is usually the most discouraging casualty when trying to account for such vortex motion, though the varying energy of this ostensibly Hamiltonian system is a potentially more serious problem. We solve these problems by a series of coordinate transformations: We first transform to action-angle coordinates, which, to lowest order, treat the close pair as a single vortex amongst all others with an internal degree of freedom. We next, and most importantly, apply Lie transform perturbation theory to remove the higher-order correction terms in succession. The overall transformation drastically increases the numerical efficiency and ensures that the total energy remains constant to high accuracy.Comment: 21 pages, 4 figure

    Extraction of Process Specific Photolithogtaphy Model Parameters

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    In order to truly represent photolithography through simulation, the exposure, bake and development models and model parameters must be accurate. Models for the pre-bake, exposure, post-exposure/pre-development bake, and the development have been developed and are available with most commercial simulators.15 The extraction of the exposure parameters has been established.13 However, the extraction of the bake and development model parameters have been subject to question\u273 given the immersion type development that has been required for the measurement of the development rate and henceforth the extraction of these parameters. Using the approach for the measurement of the in-situ development rate, developed in the first paper of this two paper series, the model parameters were extracted for Shipley 812 resist with Shipley MF312 developer. Development rates for exposures of 66, 90 and ll4rnJ/cm2 were measured. It was discovered that the set of Kim model parameters, R1 through R, were highly correlated with the combination of the Dill exposure parameters. Thus, for A=O.581pin\u27, B=O.O82im1, C=O.013cm2/mJ, the parameters R1=25.559micrometers/min, R2=1O.45lmicrometersm/min, R3=1.879, R4=O.1l2, R5=1.586, R,=0.000micrometers, and a=O.OO16im were extracted. A comparison of simulated data using the extracted model parameters with the measured data demonstrated the quality of the fit

    Geographic Patterns of Student Enrollment in Ohio's State-Assisted Universities

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    Author Institution: Department of Geography, Bowling Green State UniversityThis is a study of geographic patterns of Ohio student enrollment at Ohio's state-assisted universities using cartographic analyses in conjunction with county-based enrollment data from the Ohio Board of Regents. Because the six largest urban counties—Cuyahoga (with Cleveland), Franklin (with Columbus), Hamilton (with Cincinnati), Lucas (with Toledo), Montgomery (with Dayton), and Summit (with Akron)—provide over 50% of the college students in Ohio, one factor that has an impact on the geographic patterns of enrollment is the colleges' locations relative to those counties. Maps depicting the percentage of students from each county attending the thirteen universities generally show that geographic distance between counties and colleges influences enrollment patterns. In addition, an examination of the distance bands from which colleges attract students shows evidence of a distance decay in enrollment for the commuter universities, including Akron, Cincinnati, Shawnee State, Toledo, Wright State, and Youngstown State. In contrast, the regional universities, including Bowling Green State, Miami, Kent State, and Ohio University, are located in more rural counties and, of necessity, must attract students from beyond their local hinterlands. The status of colleges also affects their geographic patterns of enrollment. Ohio State illustrates this. Due to its large student enrollment and status as the state's flag ship university, it draws college-bound students from throughout Ohio

    Technique for the Measurement of the In-Situ Development Rate

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    In the past, a Perkin Elmer Development Rate Monitor (DRM) has been used to measure the development rate of photoresist. However, due to several limitations of the DRM, the development rates measured therein, are not truly representative of the resist processing on a production lire. Subtleties in the development system are not obtained through the DRM and hence an in-situ development rate is required. Using a Site Services Development Spray Monitor (DSM 100) and a post processing algorithm. the in-situ measured development rates were obtained. The interference signals for eight different wavelengths were simultaneously monitored on a pattemed wafer as it spun on the development module of a wafer track. Since the interference signal is generated from a circularly polarized light source, the DSM 100 has demonstrated robustness to the red cloud effect, developer spray, bubbles in the developer, and ambient light.\u27 Two algorithms for the calculation of the in-situ development rate are proposed. After collecting the eight interference curves, these post processing algorithms used the Marquardt Levenberg non-linear regression algorithm and a linear regression approach to find the development rate as a function of development time. Although the standing wave effect was visible in the plots of development rate versus time using both techniques, the first approach generated the better curve. A plot of development rate versus depth was generated via numerical integration of the plot of development rate versus time. Since the only equation used in the post processing algorithm is the interference relationship, this technique is equally well suited for other types of exposure and resist chemistries. Possession of the in-situ development rate could provide further insight into resist development mechanisms, the development of better models, and the extraction of photolithography model parameters that are specific to the production process

    Viewers base estimates of face matching accuracy on their own familiarity: Explaining the photo-ID paradox

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    Matching two different images of a face is a very easy task for familiar viewers, but much harder for unfamiliar viewers. Despite this, use of photo-ID is widespread, and people appear not to know how unreliable it is. We present a series of experiments investigating bias both when performing a matching task and when predicting other people’s performance. Participants saw pairs of faces and were asked to make a same/different judgement, after which they were asked to predict how well other people, unfamiliar with these faces, would perform. In four experiments we show different groups of participants familiar and unfamiliar faces, manipulating this in different ways: celebrities in experiments 1 to 3 and personally familiar faces in experiment 4. The results consistently show that people match images of familiar faces more accurately than unfamiliar faces. However, people also reliably predict that the faces they themselves know will be more accurately matched by different viewers. This bias is discussed in the context of current theoretical debates about face recognition, and we suggest that it may underlie the continued use of photo-ID, despite the availability of evidence about its unreliability
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