cssi/SciSciGPT-SciSciNet huggingface dataset:
Discrete Element Modeling for fouled railroad ballast

Abstract Fouling refers to the condition of railroad ballast when voids in this unbound aggregate layer are filled with relatively finer materials or fouling agents commonly from the ballast aggregate breakdown, outside contamination such as coal dust from coal trains, or from subgrade soil intrusion. This paper aims to investigate the effect of fouling on ballast strength and stability. Fouling mechanism was first explained followed by investigation of mechanical properties of fouling agent. Coal dust was chosen as the fouling agent due to its poor mechanical properties and it had been reported to mostly decrease aggregate assembly strength comparing to other fouling agents. An image-aided Discrete Element Modeling (DEM) approach was introduced to simulate the coal dust fouled track field settlement performance. To that end, DEM model parameters for clean and coal dust fouled ballast were validated by matching the DEM direct shear box simulation results to the laboratory shear box testing results for both samples. By assigning laboratory calibrated model parameters to the “half-track” ballast sample generated in DEM, effects of different fouling percentage as well as different fouling locations on ballast settlement performance are studied. Results from the “half-track” DEM simulation revealed that fouling could lead to unfavorable track distresses such as “hanging tie”. Further, shoulder fouling scenario was proven to be critical in track maintenance.
Growth and Structure of Tungsten Carbide-Transition Metal Superlattices

Superlattices between ceramic materials, such as tungsten carbide, and transition metals have been synthesized for the first time. The growth and structure of these superlattices were investigated by low angle X-ray diffraction and TEM lattice imaging and microdiffraction. The data show that the low temperature process of forming these two dimensional composites leads to unique crystal structures and morphology in the nanoscale range.
Issues with ethernet parametric testing in a production enviroment

Ethernet is an emerging communication technology in the avionics industry. There are many advantages to utilizing ethernet that include a very high data rate, some noise immunity, weight savings, and commercially available equipment. Some of the disadvantages include extra line replaceable units (LRUs) on the plane (ethernet switches) and added difficulties in aircraft wiring. This new technology brings with it many challenges in an automated test equipment (ATE) environment including, signal distortion, connector repeatability, and expensive measurement equipment.
Player salaries, organizational efficiency, and competitiveness in Major League Baseball.

The dramatic growth of free agency in Major League Baseball has caused great concern about the competitiveness of some teams, particularly those in smaller markets. The authors use a two-stage data...
Benzo[a]pyrene-DNA adduct formation in target cells in a cell-mediated mutation assay

In order to analyze the adducts formed in V79 Chinese hamster target cells in a Syrian hamster embryo (HE) cell-mediated mutation assay, a procedure was developed in which the HE cells are differentially killed when the mixed cell suspension is treated with antiserum to Syrian HE cells and complement. The V79 cell suspension, separated from lysed HE cells by gradient centrifugation, is greater than 90% HE cell-free. When the carcinogen--DNA interaction products formed in these two cell types were analyzed after exposure to [3H]benzo[a]pyrene (B[a]P) for 24 h under the conditions of a cell-mediated mutation assay, the major B[a]P--DNA adducts in both cell types resulted from reaction of the anti and syn isomers of B[a]P-7,8-diol-9,10-epoxide with DNA. The amount of B[a]P bound/mg DNA in the target cells was only 30% less than in the activator cells, and the relative proportions of the adducts of the syn and anti isomers were similar in the two cell types. The target cells, which do not metabolize B[a]P, were also unable to metabolically activate B[a]P-7,8-diol to DNA-binding metabolites. Thus, the transfer of activated B[a]P metabolites from activator cells to the DNA of target cells is a relatively efficient process that appears to be independent of the relative reactivity of specific metabolites with cellular nucleophiles. The immunological cell separation procedure we describe can be adapted to the analysis of carcinogen--cell interaction products formed in cell-mediated assays in which other types of activator and target cells are used to measure either mutation or another biological endpoint.
ON THE APPROXIMATION OF CONTINUOUS TIME THRESHOLD ARMA PROCESSES

Threshold autoregressive (AR) and autoregressive moving aver- age (ARMA) processes with continuous time parameter have been discussed in several recent papers by Brockwell et al. (1991, Statist. Sinica, 1,401-410), Tong and Yeung (1991, Statist. Sinica, 1, 411~30), Brockwell and Hyndman (1992, International Journal Forecasting, 8, 157 173) and Brockwell (1994, J. Statist. Plann. Inference, 39, 291 304). A threshold ARMA process with boundary width 25 > 0 is easy to define in terms of the unique strong solution of a stochastic differential equation whose coefficients are piecewise linear and Lipschitz. The positive boundary-width is a convenient mathematical device to smooth out the coefficient changes at the boundary and hence to ensure the existence and uniqueness of the strong solution of the stochastic differ- ential equation from which the process is derived. In this paper we give a direct definition of a threshold ARMA processes with 5 -- 0 in the important case when only the autoregressive coefficients change with the level of the pro- cess. (This of course includes all threshold AR processes with constant scale parameter.) The idea is to express the distributions of the process in terms of the weak solution of a certain stochastic differential equation. It is shown that the joint distributions of this solution with 5 = 0 are the weak limits as 5 $ 0 of the distributions of the solution with (~ > 0. The sense in which the approximating sequence of processes used by Brockwell and Hyndman (1992, International Journal Forecasting, 8, 157-173) converges to this weak solution is also investigated. Some numerical examples illustrate the value of the latter approximation in comparison with the more direct representation of the process obtained from the Cameron-Martin-Girsanov formula. It is used in particular to fit continuous-time threshold models to the sunspot and Canadian lynx se- ties.
The Contemporary Presidency: The Greats and the Great Debate: President William J. Clinton's Use of Presidential Exemplars

This article examines President William J. Clinton's use of presidential exemplars from 1991 to 2001. While many observers have called attention to the fact that Clinton made efforts to connect his presidency to Democratic “greats” Thomas Jefferson and Franklin Roosevelt, his rhetoric reveals a more complex pattern of identification and use of his predecessors. Not only did he reference Abraham Lincoln and Theodore Roosevelt—Republican “greats”—as often as Thomas Jefferson and Franklin Roosevelt, but he appears to have used them to talk across party lines and move his fellow partisans to the center. This rhetorical pattern became more prominent after the 1994 midterm election, when the Republicans won majority control of Congress. Hence, this article asserts that Clinton used his predecessors to help him carry out his political agenda and his constitutional duties. Further, he learned from his predecessors about how they had used ideological and partisan constructs during their administrations, and this led to his reconsidering the “great debate” between Jefferson and Hamilton. This research concludes that President William J. Clinton left a Hamiltonian—not Jeffersonian—legacy for the Democratic party.
Cell kinetics in the small intestine of suckling rats I. Influence of hypophysectomy

Cell kinetics have been examined in the duodena of intact rats at 6, 16, and 22 days of age, and of hypophysectomized rats at 22 days. In intact rats the crypt population per villus increases more than 10-fold, the greater part of the increase occurring late in the third week. The labelling index does not differ between 6 (28.3%) and 16 (27.6%) days, but increases to 37.8% at 22 days. Generation time also does not differ between 6 (18.0 hours) and 16 (17.7 hours) days, but falls to 10.8 hours at 22 days by shortening of both the presynthetic and synthetic phases. Acceleration of cell migration rate between 18 and19 days of age results in shortening of cell transit time from seven days in rats younger than 18 days to two days in those older than 18 days. When rats are hypophysectomized at six days, the duodenal crypt population per villus at 22 days is comparable to that of intact rats at 16 days. The labelling index at 22 days is 19% below that of intact rats at six days. Generation time at 22 days is slightly shortened by a decrease of the presynthetic phase, but the duration of 15.5 hours is 43% longer than in intact rats at the same age. Despite the small crypt population and the low cell production rate, the cell-transit time in 22-day-old hypophysectomized animals is only three days.
External pressure loading, vibration, and acoustic responses at low frequencies of building components exposed to impulsive sound

Abstract This paper presents the formulation and experimental validation of a numerical tool that can predict: (1) the external pressure loading due to impulsive sound generated by an outdoor point source and (2) the resulting fully coupled vibro-acoustic response at low frequencies of a two-dimensional building component (e.g. wood-framed wall with windows) backed by a rigid rectangular cavity. The model allows for the building component to have arbitrary geometry and boundary conditions. Assuming linear-acoustic propagation and acoustically rigid surfaces, the external pressure loading is computed with a three-dimensional numerical model, in the time domain, by combining the image-source method for the reflected field (specular reflections) with an extension of the Biot–Tolstoy–Medwin (BTM) method for the diffracted field. The fully coupled vibro-acoustic response of the fluid–structure system is computed in the time-domain using a modal-decomposition approach. The natural frequencies and mode shapes of the structure are computed with a finite-element model based on shell theory. Acoustic natural frequencies and mode shapes of the cavity are computed analytically assuming hard-wall boundary conditions. The experimental validation of the numerical model is also presented. Experiments were conducted on wood-framed walls without and with a window using a speaker to generate N-waves and load the walls structurally. It is found that numerical simulations are in good agreement with experimental data for these two cases.
A Culturally Competent Approach to Exploring Barriers in Organ Donation Consent Among Haitian Immigrants: Formative Focus Group Findings and Implications

African Americans consent to donation less often than whites, have fears and misconceptions about donation specific to their cultures, and wait longer to receive transplants when the need is identified. However, there is less detailed empirical data on the transplant needs and barriers for Haitian immigrants. This paper describes focus group results designed to identify culturally grounded beliefs, attitudes, and barriers to organ donation. Results were used to design and implement the “Bay Lavi” (Give Life) campaign designed to raise awareness and increase organ donation consent among Haitian Immigrants.
An Assessment of Nestling Diet Composition in the Violet-Green Swallow (Tachycineta thalassina)

Abstract Aerial insectivores have undergone marked population declines in recent decades, including members of the Hirundinidae (swallows), which have long served as sentinels of environmental change. In contrast to other swallow species that breed in North America, we have a poor understanding of most aspects of the basic ecology and life history of the violetgreen swallow (Tachycineta thalassina), a widespread species found throughout the Pacific Northwest. In this study, we investigated the diet composition of violet-green swallow nestlings to document the consumption of food resources by offspring during adult feeding visits. We identified arthropods from 13 taxonomic orders in feeding boluses and found that representation of taxonomic groups was highly uneven and dominated by Diptera and Hemiptera. Although swallows did provision some large prey, the great majority (i.e., 92.6% of 1047) of food items were < 5 mm in length. Feeding boluses collected from the congeneric tree swallow (T. bicolor) at the...
Recent developments in structure–activity relationships for steroid modulators of GABAA receptors

Abstract GABAergic neurotransmission can be both positively and negatively modulated by steroids. The steroid effects are thought to be mediated by binding of steroids to specific sites on GABAA receptors. It appears that the receptor sites for positive and negative modulatory steroids are different. Thus far, the location and number of binding sites for steroids on these receptors have not been established. In this brief review, we concentrate largely on results from our own structure–activity studies. Novel analogues have been studied to further delineate the structural features required for compounds to modulate receptor function via steroid binding sites. Non-naturally occurring enantiomers of both positive and negative modulators have been studied to provide further evidence for the existence of specific steroid binding sites on the receptors.
Self-similarity of Mean Flow in Pipe Turbulence

Based on our previous modi…ed log-wake law in turbulent pipe ‡ows, we invent two compound similarity numbers (Y;U), where Y is a combination of the inner variable y + and outer variable �, and U is the pure eect of the wall. The two similarity numbers can well collapse mean velocity pro…le data with dierent moderate and large Reynolds numbers into a single universal pro…le. We then propose an arctangent law for the buer layer and a general log law for the outer region in terms of (Y;U). From Milikan's maximum velocity law and the Princeton superpipe data, we derive the von Karman constant � = 0:43 and the additive constant B � 6. Using an asymptotic matching method, we obtain a self-similarity law that describes the mean velocity pro…le from the wall to axis; and embeds the linear law in the viscous sublayer, the quartic law in the bursting sublayer, the classic log law in the overlap, the sine-square wake law in the wake layer, and the parabolic law near the pipe axis. The proposed arctangent law, the general log law and the self-similarity law have been con…rmed with the high-quality data sets, with dierent Reynolds numbers, including those from the Princeton superpipe, Loulou et al., Durst et al., Perry et al., and den Toonder and Nieuwstadt. Finally, as an application of the proposed laws, we improve the McKeon et al. method for Pitot probe displacement correction, which can be used to correct the widely used Zagarola and Smits data set. Nomenclature A = constant in the arctangent law, Eq. (19) B = additive constant in the classic log law, Eq. (9) B1 = additive constant in Millikan's log law of the maximum velocity, Eq. (10) C = model constant in the self-similarity law, Eq. (26) Dp = diameter of Pitot probe in Eq. (30) f = generic function ki = coe¢ cients in the arctangent law, Eq. (19), where i = 1;2;3;��� U = similarity number representing the pure eect of the wall, Eq. (14e) u = mean velocity at distance y from the wall umax = maximum velocity at the pipe center u + = dimensionless maximum velocity, u + = umax=u� u + = dimensionless velocity scaled by the shear velocity, u + = u=u� u� = shear velocity R = radius of pipe Re = bulk Reynolds number Re� = Krmn number Y = similarity number combining the inner and outer variables, Eq. (14d) y = distance from the wall yc = true velocity at the center of the probe in Eq. (31) y + = inner variable, y + = yu?=�
Mineral adequacy, exploration success, and mineral policy in the United States☆

Abstract Data on copper reserves, recent discovery rates, and historical tonnage-grade relations indicate that the U.S. can be approximately self-sufficient in copper to the year 2000 by mining grades similar to those presently being mined, and given reasonable exploration efforts, the U.S. can supply its demand for about 100 years by mining inferred tonnages above 0.1% Cu. However, recent price trends and the increased cost of mining lower grade ore will increase the price of copper at a rate faster than the general inflation rate, and may lead to significant imports because of their cheaper price. Compilation of the discovery history for copper shows that the Hubbert Gaussian curve is not applicable to predict copper reserves, and may not be applicable for other commodities. A compilation of the value of base and precious metal deposits discovered since 1940, along with meager data on cost and manpower used in exploration, indicates very little decrease in exploration effectiveness over the 40-year interval, in contrast to oil and uranium. Collection of better data on expenditures for metallic mineral exploration is recommended.
Structure elucidation of a novel acidic tetrasaccharide and hexasaccharide derived from a chemically modified heparin.

In the course of development of potentially more bioactive forms of heparin’ for use as an anticoagulant, we had occasion to prepare a modified heparin first reported by Jaseja et al.‘. Treatment of unfractionated bovine lung heparin with an alkaline solution at high temperature (105-110°C) for 24 h, according to method developed by Rej and Perlin3, results in a modified heparin. To structurally characterize the sample of modified heparin, it was depolymerized with heparinase (heparin lyase I, EC 4.2.2.7). This resulted in the isolation of the hitherto unreported tetrasaccharide and hexasaccharide. This note describes the isolation and structure elucidation of two novel oligosaccharides. The solution conformation of these oligosaccharides may aid in developing a better understanding of the conformational preferences of the uranic acid residues. Treatment of heparin with a sodium carbonate solution according to the method developed by Perlin and co-workers2$ results in a modified heparin. However, because heparin is a polydisperse microheterogeneous mixture, the modified heparin is also a mixture, and thus its precise structure was ill-defined. The ‘H NMR spectrum of the intact modified polymer indicated the presence of
Good bones: anthropological scientific collaboration around computed tomography data

We report preliminary results from a socio-technical analysis of scientific collaboration, specifically a loosely connected group of physical anthropology researchers. Working from a combination of interview data and artifact analysis, we identify current barriers to the scientists' collaboration as it relates to a valuable but scarce resource, a high-resolution computer tomography scanner. We analyze a two-layer structure of the collaboration, one that is loosely coupled through shared scanner access and use; and one that is tightly coupled through shared creative development of research questions, data analysis and interpretation. We conclude with implications for enhancements to the sociotechnical context and supporting infrastructure.
Inhibitory Effects of ▵9-Tetrahydrocannabinol on Glycolytic Substrates in the Rat Testis

Experiments conducted with rat testicular tissue indicated that Δ9-tetrahydrocannabinol (THC) produced a dose-dependent inhibition of glucose metabolism. Incubation of testicular tissue wit
Intimate Partner Violence among Asian Americans: Risk Factor Differences across Ethnic Subgroups

A limited number of studies have been conducted on intimate partner violence (IPV) among Asian Americans. This study aims to fill this gap by examining risk factors for IPV and ethnic differences within Asian American subgroups. Logistic regression analyses were conducted, using data from the National Latino and Asian American Study (NLAAS). This study found that while prevalence rates of IPV varied across ethnic groups, the differences disappeared when controlling for demographic, interpersonal, and sociocultural variables. The study findings also showed that risk for IPV was higher for US-born Asian Americans, and that perceived discrimination increased the risk.
Parallel optimization for traffic assignment

Most large-scale optimization problems exhibit structures that allow the possibility of attack via algorithms that exhibit a high level of parallelism. The emphasis of this paper is the development of parallel optimization algorithms for a class of convex, block-structured problems. Computational experience is cited for some large-scale problems arising from traffic assignment applications. The algorithms considered here have the property that they allow such problems to be decomposed into a set of smaller optimization problems at each major iteration. These smaller problems correspond to linear single-commodity networks in the traffic assignment case, and they may be solved in parallel. Results are given for the distributed solution of such problems on the CRYSTAL multicomputer.
Perturbational solutions of the boltzmann transport equation for n+ nn+ structures

A perturbational, moments-of-the-Boltzmann-equation approach (PMBE) is used to obtain the impedance Z and propagation constant k of n+nn+ diode structures in an analytical fashion. Evaluation of Z and k is relatively inexpensive so that hundreds of distinct boundary conditions (BC), corresponding to a single set of interior device parameters, may be studied. Based on such PMBE analytically obtained BC results, a few of the more interesting BC cases could be simulated enlisting a large signal, time domain, spatially varying numerical code. An example of a PMBE computer run is provided for a 0.4 μm thick device with a donor doping density of 1015/cm3 in the 100–300 GHz frequency spectrum.
Influence of nonadiabaticity and nonlinearity on the operation of cold-atom beam splitters

The operation of cold-atom beam splitters is analyzed in the context of Bose-Einstein condensate interferometry. We introduce two representative geometries of the splitting region and study influence of nonlinearity and nonadiabaticity on the splitting and the recombination of the condensate for both geometries.
Terminal Speeds and Ion Fractions from [Ca IV] 3.207 μm in Three Single WN Stars*

We report on the forbidden emission lines of [Ca IV] at 3.207 μm and [Ne III] at 15.56 μm based on Infrared Space Observatory observations. The data set consists of three single Wolf-Rayet stars (WR 1, WR 134, and WR 136) and three binary systems (WR 11, WR 146, and WR 147). For the single stars, only the [Ca IV] line was observed. Our primary objectives are to determine the wind terminal speed from the emission-line widths, derive ion number fractions, and discuss the relation between emission profile shapes and wind flow geometry. Compared to previous determinations of the terminal speed, we find values that are similar or somewhat smaller. Interestingly, the line width at the continuum level is typically 10%-30% broader than at the half-maximum level. The extra broadness suggests the effect of turbulence in the wind. For the ion fraction, we assume that calcium is not enriched in any of the W-R winds. Ion fractions of Ca+3 and Ne+2 are derived for the binary systems and found to be consistent with previously published values. For the new observations of the single WN stars, all of the ion fractions for Ca+3 have similar values, which are close to the maximum expected value, thus suggesting that Ca+3 is the dominant ion at large radii in the wind. Finally, the line profile shapes in the binaries WR 11, WR 146, and WR 147 appear asymmetric, as might be expected from such systems. For WR 136, the [Ca IV] profile is flat-topped, consistent with a spherical flow. For WR 1 and WR 134, the [Ca IV] profiles are too weak to draw conclusions about the wind flow geometry.
Microwave sterilization of hydrophilic contact lenses

We used standard 2,450-MHz microwave irradiation to achieve sterilization of hydrophilic contact lenses contaminated with a variety of bacterial, fungal, and viral corneal pathogens. A three-dimensional rotisserie was used to overcome the problem of "cold spots" within the microwave oven. The contact lenses became dehydrated in approximately two minutes. Rehydration with normal saline restored their shape and appearance. The time necessary to prohibit all growth of the bacterial and fungal organisms studied ranged from 45 seconds to eight minutes. All viral contaminants were completely inactivated after four minutes of microwave exposure. Refractive properties were unaffected after 101 exposures to microwaves for ten minutes. Slit-lamp examination and scanning electron microscopy disclosed minute particles on the surface of these contact lenses but no damage to the lens matrix from irradiation.
Worst case product performance verification with electromagnetic interference test applications

When many variables are prevalent, it is difficult systematically to identify the optimum configuration for product certification. This need can occur in areas such as testing performance of closed-loop servo systems and testing products for electromagnetic interference (EMI). This paper proposes a test strategy to identify a 'determined worst case expected' product configuration and a criterion for pass/fail. The process was developed originally for EMI test applications; however, it can also be useful for other product performance specifications.
Ferroelectricity in Water Ice

Partially proton-ordered ice I (cubic) was grown from the vapor phase, from 40 to nearly 150 K. It is believed to be metastable and oriented by the asymmetry of the solid−vacuum interface during growth. This was studied using a Kelvin (work function) probe for ice grown on a single-crystal Pt(111) substrate. The ice grows with a slight preference for the O-end aimed away from the surface, with about 0.2% net up dipole per water molecule at 40 K, or about −3 mV/monolayer of deposited ice film. This decreases with deposition temperature as exp(−T/27 K). Near 130, 140, and 150 K sharp features occur as the ice changes from amorphous to crystalline, and dielectric properties become active. By 150 K the effect seems to be zero. These results are discussed in context with other recent reports on ferroelectric ice. In addition to influencing several kinds of vacuum-based studies of ice, this slight ferroelectricity may allow natural ice vapor-grown in space to develop large electric fields.
Enhanced Methanol Yields from the Direct Partial Oxidation of Methane in a Simulated Countercurrent Moving Bed Chromatographic Reactor

A laboratory-scale simulated countercurrent moving bed chromatographic reactor (SCMCR) for the direct, homogeneous partial oxidation of methane to methanol has been constructed and tested. Reaction conditions were evaluated from independent experiments with a single-pass tubular reactor. Separation was effected by gas−liquid partition chromatography with 10% Carbowax on Supelcoport. At the optimal reaction conditions of 477 °C, 100 atm, and feed methane-to-oxygen ratio of 16, the methane conversion in the SCMCR was 50%, the methanol selectivity was 50%, and the methanol yield was 25%. Factors affecting methane conversion were investigated. Possible ways to improve the methane conversion, and hence the methanol yield, are discussed.
Resistance of green building materials to fungal growth

While the market for “green” building materials has been expanding rapidly, the susceptibility of these materials to fungal growth is not well understood. The relative fungal resistance of four pairs of green building materials and their conventional analogs was assessed. An artificial inoculation protocol was used to investigate the effects of external nutrient levels, host material, and spore levels on the susceptibility of building materials to Aspergillus niger. Also, a natural inoculation protocol was utilized to evaluate the resistance of the building materials to colonization by common indoor fungi. Increasing spore levels and the presence of external nutrients promoted the growth of A. niger on the surface of drywall, conventional ceiling tile, and gypsum wallboard. Following natural inoculation, a strong correlation was found to exist between the equilibrium moisture content (EMC) of organic-based materials and the time until 50% of the total surface area of a material specimen was covered by fungi (T50%). Fungal growth rates on the top, back, and side surfaces of coated or composite building materials were quite different. The results suggest that the presence of organic matter in a given building material and its EMC are more important predictors of fungal susceptibility than is the label of “green” or “non-green”.
RIGHT ATRIAL FUNCTION IS IMPAIRED IN PULMONARY ARTERIAL HYPERTENSION AND REFLECTS RIGHT VENTRICLE FAILURE: THE IMPRES TRIAL

Right atrial (RA) pressure is a known prognostic measure in pulmonary arterial hypertension (PAH). However, little is known about RA function in PAH We used myocardial deformation imaging by speckle tracking to study RA function. Reservoir (RA strain), conduit (RA early strain rate [eSR]), and
The in vitro metabolism of 3α,17β-androstanediol by liver and kidney

Abstract 3α,17β-Androstanediol was metabolized in vitro by homogenates of rat, guinea pig, and rabbit liver and kidneys. The metabolites isolated or indicated as present were androsterone, epiandrosterone, and 3,17-androstanedione. The total amount of conversion to these substances was less than 5%, and more than 90% of the original material was accounted for. Rabbit liver slices were no more effective than the homogenates.
Dehydroquinate synthase from Escherichia coli: purification, cloning, and construction of overproducers of the enzyme

Dehydroquinate synthase has been purified 9000-fold from Escherichia coli K-12 (strain MM294). The synthase is encoded by the aroB gene, which is carried by plasmid pLC29-47 from the Carbon-Clarke library. Construction of an appropriate host bearing pLC29-47 results in a strain that produces 20 times more enzyme than strain MM294. Subcloning of the aroB gene behind a tac promoter results in E. coli transformants that produce 1000 times more enzyme than MM294: the synthase constitutes 5% of the soluble protein of the cell. A laborious isolation from 50 g of wild-type E. coli cells yields 80 micrograms of impure enzyme, whereas 50 g of cells containing the subcloned gene yields 150 mg of homogeneous enzyme in a two-column purification. Dehydroquinate synthase is a monomeric protein of Mr 40 000-44 000. The chromosomal enzyme from E. coli K-12, the cloned enzyme encoded by the plasmid pLC29-47, and the subcloned inducible enzyme encoded by pJB14 all comigrate on polyacrylamide gel electrophoresis under denaturing conditions.
A design process model for computer integrated structural engineering

Computer integrated design systems will require an improved understanding of the engineering design process, including formalized notions of (1) the structure of the process, (2) the design tasks that need to be performed, and (3) the information required to carry out these tasks. To help formalize the design process, certain conceptual tools are needed, including an organizational model for the process. This paper outlines such a model for structural engineering design, termed theMultilevel Selection-Development model, which is based on a decomposition of design problems intoselection anddevelopment subproblems. A few basic concepts involved in the engineering design process are reviewed, and the proposed model is outlined. The application of the model to a simple example is presented, and management of the interactions between subproblems is discussed.
Strategies for improved interpretation of computer-aided detections for CT colonography utilizing distributed human intelligence

Abstract Computer-aided detection (CAD) systems have been shown to improve the diagnostic performance of CT colonography (CTC) in the detection of premalignant colorectal polyps. Despite the improvement, the overall system is not optimal. CAD annotations on true lesions are incorrectly dismissed, and false positives are misinterpreted as true polyps. Here, we conduct an observer performance study utilizing distributed human intelligence in the form of anonymous knowledge workers (KWs) to investigate human performance in classifying polyp candidates under different presentation strategies. We evaluated 600 polyp candidates from 50 patients, each case having at least one polyp ⩾6 mm, from a large database of CTC studies. Each polyp candidate was labeled independently as a true or false polyp by 20 KWs and an expert radiologist. We asked each labeler to determine whether the candidate was a true polyp after looking at a single 3D-rendered image of the candidate and after watching a video fly-around of the candidate. We found that distributed human intelligence improved significantly when presented with the additional information in the video fly-around. We noted that performance degraded with increasing interpretation time and increasing difficulty, but distributed human intelligence performed better than our CAD classifier for “easy” and “moderate” polyp candidates. Further, we observed numerous parallels between the expert radiologist and the KWs. Both showed similar improvement in classification moving from single-image to video interpretation. Additionally, difficulty estimates obtained from the KWs using an expectation maximization algorithm correlated well with the difficulty rating assigned by the expert radiologist. Our results suggest that distributed human intelligence is a powerful tool that will aid in the development of CAD for CTC.
922-60 How Positionally Stable is a Transesophageal Echo Probe During 3 Dimensional Imaging? Implications for 3 Dimensional Reconstruction

Three dimensional (3D) reconstruction from a single esophageal scanning position requires a stable relationship between the probe and the heart. The purpose of this study was to examine the movement of a transesophageal echo (TEE) probe during 3D image acquisition. A new dual axis multiplane probe was used which includes a miniature (6 × 6 × 9 mm) 6D sensor in the tip. The sensor identifies the probe's 3D position and orientation in space with respect to the location of a magnetic field generator placed beneath the subject. In vivo 3D scans were performed in 5 anesthetized, ventilated dogs. Positional determinations were acquired every 66 ms. The sensor axes were: x-mediolateral. y-superoinferior, z-anteroposterior, and r-radial distance = √(x2 + y2 + z2). The movement was estimated by computing standard deviations of the x, y, and z positions during each 3D scan and each cardiac cycle. From 2337 determinations, the mean standard deviation for 10 3D scans and 264 cardiac cycles and histograms of the radial movement were calculated and are shown. x(mm) y(mm) z(mm) r(mm) Total 3D scans 0.63 ± 0.63 0.56 ± 0.64 0.65 ± 0.45 0.57 ± 0.43 Cardiac cycle 0.28 ± 0.36 0.21 ± 0.28 0.25 ± 0.35 0.24 ± 0.35 Conclusion Probe movement during 3D imaging is measurable and in these anesthetized subjects was within acceptable limits. This capability will be useful in awake patients where greater movement is expected, and will optimize the 3D data set by discarding scans where significant probe movement has occurred.
Observations of deep convective clouds as stable reflected light standard for climate research: AIRS evaluation

Changes of the order of 1%/decade or less are expected in the tropical ocean cloud amount due to global warming. Since the ocean is very dark in the visible and near infrared region of the spectrum, a change in the Earth reflectance is equivalent to a measure of the change in the cloud cover. A reliable measurement of such a small change in the visible requires a reference source which is much more stable than 1%/decade. A procedure is developed to use the sunlight reflected from Deep Convective Clouds (DCC) as a stable and readily available reference source for reflected light channels. The procedure uses the stability of the NIST traceable infrared radiometric calibration of the Atmospheric Infrared Sounder (AIRS) to create a stable DCC detection threshold, which assures a stable visible reflected reference signal. DCC are identified in the data as any IR footprint within ±30 degree latitude, where the brightness temperature in the 1231 cm -1 window channel is 210K or less. The 90%tile value of the observed visible signal is used as reference to minimize the effect of under-filling the footprint. Typically 2000 DCC are identified each day during the daylight part of the orbit. The stability uncertainty in the DCC reference signal measured from the first four years of AIRS data is 0.02%/year, i.e. 0.2%/decade. The stability of the procedure demonstrated with AIRS is thus already better than the 1%/decade expected change in the cloud amount due to global warming. Extrapolated from four years to the expected 12 year lifetime of AIRS the trend uncertainty on the DCC measurements should decrease to 0.06%/decade. A 12 year record of the Earth reflectance stabilized with the DCC would allow for a very sensitive test of a change in the cloud amount. AIRS was launched on the EOS Aqua spacecraft in May 2002 into a 705 km polar sun-synchronous orbit with accurately maintained 1:30 PM ascending node. Essentially un-interrupted data are freely available since September 2002. The DCC are included in the AIRS Calibration Data Subset (ACDS).
Case report 624

A stress fracture occurring in the distal tibial metaphysis is presented. This fracture occurred in an area of disuse osteoporosis approximately 3 months following a gross traumatic fracture of the more proximal portion of the tibia. A stress fracture of the distal tibial metaphysis occurring secondary to a bimalleolar fracture of the same bone is also cited. The clinical settings in which tibial stress fractures have been reported are reviewed, as well as the difficulties inherent in the diagnosis and management of this entity.
Lateral Wedges Decrease Biomechanical Risk Factors for Knee Osteoarthritis in Obese Women

Abstract Obesity is the primary risk factor for the development and progression of medial compartment knee osteoarthritis. Laterally wedged insoles can reduce many of the biomechanical risk factors for disease development in osteoarthritis patients and lean individuals but their efficacy is unknown for at-risk, obese women. The purpose was to determine how an 8° laterally wedged insole influenced kinetic and kinematic gait parameters in obese women. Gait analysis was performed on fourteen obese (average 29.3 years; BMI 37.2 kg/m2) and 14 lean control women (average 26.1 years; BMI 22.4 kg/m2) with and without a full-length, wedged insole. Peak joint angles, the external knee adduction moment and its angular impulse were calculated during preferred and standard 1.24 m/s walking speeds. Statistical significance was assessed using a 2-way ANOVA (α=0.05). The insole significantly reduced the peak external knee adduction moment (mean decrease of 3.6±3.9 Nm for obese and 1.9±1.8 Nm for controls) and its angular impulse in both groups. The wedged insoles also produced small changes in ankle dorsiflexion (obese: 1.2±1.4° increase; control: 1.5±1.4° increase) and eversion range of motion (obese: 1.3±1.9° decrease; control: 1.5±1.2° decrease) but did not alter peak angles of superior joints. Although the majority of obese women may develop knee osteoarthritis during their lifetime, a prophylactic insole intervention could allow obese women with no severe knee malalignments to be active while preventing or delaying disease onset. However, the long-term effects of the insole have not yet been examined.
High-Order Local Time Stepping on Moving DG Spectral Element Meshes

We derive and evaluate an explicit local time stepping (LTS) integration for the discontinuous Galerkin spectral element method on moving meshes. The LTS procedure is derived from Adams---Bashforth multirate time integration methods. We also present speedup and memory estimates, which show that the explicit LTS integration scales well with problem size. Time-step refinement studies with static and moving meshes show that the approximations are spectrally accurate in space and have design temporal accuracy. The numerical tests validate theoretical estimates that the LTS procedure can reduce computational cost by as much as an order of magnitude for time accurate problems.
Joint effects of medial septal lesions and amylobarbitone injections on resistance to extinction in the rat.

32 male rats, of which half had sustained small electrolytic lesions in the medial septal area and half had received sham operations, were trained on continuous reinforcement to run an alley for water reward and then given four days of extinction testing. Half of both the lesioned and sham-operated groups were given sodium amylobarbitone on Days 1 and 2 of extinction and the other half on Days 3 and 4, saline being administered on non-drug days. The drug, unusually, decreased resistance to extinction. This effect was probably due to the subjects having taken part in a previous experiment in which they had received, without drugs, training and extinction under the same conditions as in this experiment. In the goal section of the alley, the drug effect was greater in lesioned than shamoperated rats. The lesions retarded extinction, and this effect was reduced by the drug. A model for the neural loci at which amylobarbitone acts to affect resistance to extinction, based on these and other results, is proposed.
Endovascular Treatment of an Aortobronchial Fistula

A 67-year-old man operated on 8 years previously for type B aortic dissection presented with two episodes of massive hemoptysis. An aortobronchial fistula was suspected with spiral computed tomography angiography, and showed a small pseudoaneurysm corresponding to the distal anastomotic site. The patient underwent endovascular stent-graft implantation and is asymptomatic 8 months after the procedure.
The Uptake and Metabolism of Brassinosteroid by Tomato (Lycopersicon esculentum) Plants

Summary When brassinosteroids (BR) are applied to the roots of hydroponically grown tomato plants there is an accumulation of 1-aminocyclopropane-l-carboxylic acid (ACQ in the leaves. In this work, BR-induced ethylene production in tomato plants was studied further using 3HBR. Twenty day old tomato plants were incubated in 25 mL Hoagland’s solution plus 1.1 µMBR and 3.7 x 106cpm of 3HBR. During incubation the tomato plants accumulated ACC and extractable radioactivity. The 24-h plant extracts contained 2695 nmolkg-1 (fresh mass basis) of ACC compared with 73 nmolkg-1 in the control. The 24-h treated plant extracts also contained over 2.12 × 106 cpm kg-1 of tritium. Migration of the radioactivity on silica gel TLC plates showed there was no apparent metabolism of BR during the first four hours; however, by 8 h there were two radioactive spots on the plate. The 12-h extract contained 3 radioactive spots, the original BR plus two metabolic products. When plants were incubated with BR for 24 h and transferred to BR-free Hoagland's solution, the ACC content of the tissues decreased and there was an increase in the amount of tritium migrating as BR metabolites. The plant apparently metabolizes BR to inactive forms, and the overproduction of ethylene ceases. The identities of these metabolic products are unknown at this time.
A HALOTOLERANT PLANOCOCCUS FROM ANTARCTIC DRY VALLEY SOIL

A halotolerantPlanococcus (strain A4a) was isolated from saline Antarctic Dry Valley soil.Planococcus strain A4a grew over wide ranges of temperature (0°C−40°C) and NaCl concentrations (0–2.0M). When the NaCl concentration of the growth medium was increased, the total intracellular free amino acid concentration increased; however, the intracellular potassium concentration did not increase. This result suggested that intracellular free amino acids functioned as compatible solutes for growth ofPlanococcus strain A4a at elevated NaCl concentrations. The halotolerant and psychrotolerant nature ofPlanococcus strain A4a would appear to provide it with the capacity for growth in the saline Antarctic Dry Valley soil environment from which it was isolated.
A HYBRID ELECTRO-OPTICAL ARCHITECTURE FOR CLASSIFICATION TREES AND ASSOCIATIVE MEMORY MECHANISMS

An architecture is presented here which can be used for some important paradigms of intelligent systems. This architecture targets applications which require real time processing of stream inputs with versatile hardware which exploits parallelism. The architecture is particularly suited for pattern recognition paradigms which are based on the use of decision trees. Artificially intelligent systems based on decision trees interestingly present some common computational requirements which can be served very efficiently by a Data Flow architecture. A small set of different functions is computed repeatedly with simple result tokens passed from one computation to successive ones. Developments in optical processing have introduced elements which are particularly suited to the computational requirements of some of these systems, and therefore they can be effectively employed in this architecture. The architecture presented here is based on Data Flow design principles and is enhanced with optical processing elements. The function of the architecture is illustrated by discussing the mapping of two specific AI paradigms—a pattern classifier and an associative recall mechanism.
On-line computer augmentation of bio-feedback processes

Abstract New results in neuropsychology suggest that the so-called autonomous functions may actually be controlled to some degree by conscious, learned processes. It is essential, in the learning of such control, that feedback information about the process be made available to the subject on a fast response time. This paper suggests the use of computers in the feedback loops to provide sophisticated communication with the subject. Clinical applications, basic research problems, educational and technical implications are discussed with the view that the machine could be properly used to help us to penetrate closer to the sources of inner consciousness.
Functionalized Pentacene: Improved Electronic Properties from Control of Solid-State Order

Molecular order has proven to be a significant factor in the performance of devices based on organic semiconductors. Recent studies involving solubilized versus unsubstituted thiophene oligomers have demonstrated that modifications which increase orbital overlap in the solid state can improve device performance by more than an order of magnitude. 1 Similar studies on pentacene, a compound which has already demonstrated remarkable potential for device applications, 2 have also focused on maximizing orbital overlap by inducing order in films. 3 However, these pentacene studies have thus far relied on substrate modification, rather than on pentacene functionalization, 4 to achieve the desired goals. We report here the preparation of two functionalized pentacene derivatives, and the effect of this functionalization on both the solid-state ordering and the electronic properties of the resulting crystals. Our goal for a functionalized pentacene was two-fold: First, the substituents should impart solubility to the acene, to simplify purification and processing. Second, the substituents should induce some capability for self-assembly of the aromatic moieties into ﷿-stacked arrays to enhance intermolecular orbital overlap. We anticipated that both of these goals could be accomplished by exploiting a rigid spacer to hold the necessarily bulky solubilizing groups well away from the aromatic core, allowing the closest possible contact between the aromatic rings. 5 Our initial targets were the bis(triisopropylsilylethynyl)pentacenes 1 and 2. Both of these compounds are easily prepared in near quantitative yield in a one-pot reaction from 6,13-pentacenequinone and 5,14pentacenequinone, respectively. 6