cssi/SciSciGPT-SciSciNet huggingface dataset:
Determinants of Choice of Distribution Channels by Fish Farmers in Ughelli North Local Government Area of Delta State, Nigeria

The study examined the factors influencing fish farmers’ choice of distribution channels in the marketing of their fish in Ughelli North Local Government Area of Delta State, Nigeria. A two stage sampling procedure was adopted for the study. One hundred and twenty fish farmers were sampled for the study. Descriptive statistics was used to summarize the results of socio-economic characteristics. The logit regression model was used to estimate the parameters of the hypothesized determinants of choice of marketing channels. Four channel levels of fish distributions were identified. Fifteen percent fish production was found to be distributed by channel one, 65 percent in channel two, 18 percent in channel three and 2 percent in channel four. The study showed that age, level of education, farm size, access to information, distance to market and output price were the significant determinants of channel choice by fish farmers. The study recommended the provision of market infrastructure and technical supports in the form of information technology to farmers for the sustainability of the fish farming industry.
A RELATIVISTIC THEORY OF NUCLEAR MATTER

Nuclear matter is studied in the framework of quantum hadrodynamics (QHD). As a simple first example, the nuclear equation of state is computed in the mean-field approximation to the Walecka model (QHD-I). General principles of covariant thermodynamics and thermodynamic consistency are introduced, and these principles are illustrated by recomputing the mean-field nuclear matter properties in an arbitrary reference frame. The loop expansion is proposed as a candidate for performing reliable calculations beyond the mean-field approximation, and the one-loop vacuum corrections to the mean-field results are discussed. The two-loop corrections for nuclear matter, including vacuum polarization, are then calculated. The size and nature of the two-loop corrections indicate that the loop expansion is apparently not a useful procedure in this model. Prospects for alternative expansion schemes are discussed.
Hybrid Feedback Linearization/Fuzzy Logic Control of a Flexible Link Manipulator

A feedback-linearization/fuzzy logic control scheme for a robotic manipulator with link flexibility is designed. This control scheme is composed of a feedback-linearization inner-loop control and a fuzzy linguistic outer-loop control. A reduced-order computed torque ROCT control is first used to linearize the whole system to a Newton's-law-like system, then a linguistic fuzzy controller that consists of 33 condition-action rules is used to command the rigid modes to track the desired trajectories while maintaining the residual vibration as small as possible.
Methods to reduce nuclear medicine staff radiation exposure from 18FDG exams

1519 Objectives Use of 18FDG continues to grow in oncologic and neurologic applications as imaging sensitivity has increased and amount of time required to perform procedures has decreased. Procedures in our practice increased from 30 in 1997 to 1832 in 2010, with mean nuclear medicine technologist annual radiation exposure approximately doubling. Methods utilizing time, distance, and shielding have been evaluated in an effort to reduce exposures, with emphasis on the injection and transport of 18FDG patients. Methods A time analysis study was initially conducted to determine the aspects of an 18FDG procedure that require the longest time. Landauer TLD-100, Landauer Luxel OSD, and Mirion TLD-760 whole body dosimeters were used in our historical review of cumulative exposure while Mirion TLD-760 and Quantum Products Direct Ion Storage Instadose dosimeters were used in our prospective analysis of methods to reduce cumulative whole body exposure. All dosimeters were NVLAP approved and worn at chest level. In our prospective analysis, injection and transport activities were evaluated separately. Variability between dosimeters and effect of positioning the patient were also analyzed. Results Segregating the injection area by at least 10 feet from patients waiting to be scanned reduced nuclear medicine technologist exposure by 20%. Radiation exposure from transporting injected patients approximately 160 feet to the PET CT scanner ranged from an average of 1.23 millirem/patient (including positioning on table) to 0.59 millirem/patient (excluding positioning). During recent renovation, the injection and waiting area was moved adjacent to the PET CT scanner (40 feet from the table), resulting in a decrease in exposure during transit to 0.22 millirem/patient. Converting from a unit dose to the MEDRAD Intego injection system reduced whole body exposure from an average of 1.4 millirem/patient to 0.57 millirem/patient. Conclusions Multiple aspects of 18FDG exams are amenable to changes that reduce nuclear medicine staff radiation exposure
Multiple Narrative Disentanglement: Unraveling Infinite Jest

Many works (of both fiction and non-fiction) span multiple, intersecting narratives, each of which constitutes a story in its own right. In this work I introduce the task of multiple narrative disentanglement (MND), in which the aim is to tease these narratives apart by assigning passages from a text to the sub-narratives to which they belong. The motivating example I use is David Foster Wallace's fictional text Infinite Jest. I selected this book because it contains multiple, interweaving narratives within its sprawling 1,000-plus pages. I propose and evaluate a novel unsupervised approach to MND that is motivated by the theory of narratology. This method achieves strong empirical results, successfully disentangling the threads in Infinite Jest and significantly outperforming baseline strategies in doing so.
Social Emergence: Emergence in psychology

Theories of emergence have had a longstanding influence on psychological thought. Emergentism rejects both reductionism and holism; emergentists are scientific materialists, and yet argue that reductionist explanation may not always be scientifically feasible. I begin by summarizing the history of emergence in psychology and sociology, from the mid-19th century through the mid-20th century. I then demonstrate several parallels between this history and contemporary psychology, focusing on two recent psychological movements: socioculturalism and connectionist cognitive science. Placed in historical context, both sociocultural ism and connectionism are seen to be revivals of 19th and early 20th century emergentism. I then draw on this history to identify several unresolved issues facing socioculturalists and connectionists, and to suggest several promising paths for future
The VR-Desktop: An Accessible Approach to VR Environments in Teaching and Research

The VR-Desktop initiative is an effort to bring key benefits of projection-based virtual reality into the mainstream of teaching and research at the Pennsylvania State University, through the deployment of comparatively low cost and easy to use virtual reality and integrated multimedia display systems within a variety of contexts. Recent experiences with design and implementation of single- and multi-screen VR systems for teaching and research are described. The systems discussed employ low cost and readily available hardware components, familiar desktop computing environments, and open-source VR development toolkits. The approach is modular and easily adaptable to various applications in research or instruction.
The impact of party polarization and postmaterialism on voter turnout

. Previous research on voter turnout has concluded that institutional factors such as compulsory voting, registration laws and the degree of disproportionality of the electoral system have a determining impact on the number of people who cast their ballots. This article goes beyond such an institutional explanation. It is hypothesized that a diverse political landscape which offers a great menu of political choices to electors is more likely to have a higher voter turnout than a political system in which the differences between the parties are small. The greater the range of political expression available the more people are stimulated to vote. This study found that countries with a high party polarization have significantly higher turnout rates than countries with a rather narrow political spectrum. In addition, countries in which a ‘postmaterialist party’is present in the national parliament also display significantly higher voter turnout rates than countries which lack such a party. In order to explain the determinants of voter turnout, not only institutional variables but also intrinsically political variables such as the number of parties, the type of parties and party polarization have to be introduced. To solve the puzzle of varying voter turnout rates, ‘politics’has to be brought back in.
Prothrombin gene variants in non-Caucasians with fetal loss and intrauterine growth retardation.

Thrombotic predisposition may affect pregnancy outcome, but in non-Caucasians the contributing genetic factors are poorly characterized. Two recently identified prothrombin gene mutations (20209C>T and 20221C>T) have been observed in non-Caucasian patients with thrombosis. The mutations are located near the commonly identified variant 20210G>A and have not been reported in Caucasian patients. The authors report a novel connection with pregnancy complications. The identification of sequence variants other than 20210G>A in the 3′-untranslated region of the prothrombin gene suggests that additional nucleotide substitutions may contribute to the development of thrombotic events and adverse pregnancy outcomes, especially in less well-characterized populations.
Superquadrics-based 3D object representation of automotive parts utilizing part decomposition

We present a new superquadrics based object representation strategy for automotive parts in this paper. Starting from a 3D watertight surface model, a part decomposition step is first performed to segment the original multi-part objects into their constituent single parts. Each single part is then represented by a superquadric. The originalities of this approach include first, our approach can represent complicated shapes, e.g., multi-part objects, by utilizing part decomposition as a preprocessing step. Second, superquadrics recovered using our approach have the highest confidence and accuracy due to the 3D watertight surfaces utilized. A novel, generic 3D part decomposition algorithm based on curvature analysis is also proposed in this paper. The proposed part decomposition algorithm is generic and flexible due to the popularity of triangle meshes in the 3D computer community. The proposed algorithms were tested on a large set of 3D data and experimental results are presented. The experimental results demonstrate that our proposed part decomposition algorithm can segment complicated shapes, in our case automotive parts, efficiently into meaningful single parts. And our proposed superquadric representation strategy can then represent each part (if possible) of the complicated objects successfully.
Finite size effects in ferroelectric nanocrystals: Myths & facts

A phenomenological intrinsic finite size effect model for a single domain, mechanically free, and surface charge compensated ABO3 (PbTiO3 or BaTiO3) nanocrystals undergoing a first order tetragonal?cubic phase transition is propsoed. By using experimental particle size-dependent spontaneous polarization data for PbTiO3 and BaTiO3, free energy expansion coefficients coefficients up to the sixth order as a function of ? is computed in the range <150 nm. It will be shown that the thermodynamic potential is able to predict the size-induced phase transition as well as the metastable tetragonal phase in the cubic phase field rigorously. The free energy surface is then contructed, which describes the decrease in tetragonal phase stability with decreasing ? rigorously. The intrinsic dielectric and piezoelectric properties of single domain, mechanically free, and surface charge compensated PbTiO3 nanocrystals are then evaluated. It will be shown that a decrease in dielectric susceptibility at the transition temperature with decreasing particle size is commensurate with predictions of lattice dynamics considerations. It will also be shown that an anomalous increase in piezocharge coefficients near ~15 nm is predicted. Finite size effects will then be discusssed in terms of depolarization fields, surface effects, role of defects, among others and salient aspects of myths & facts in the published literature will be analyzed.
Kantorovich-ostrowski convergence theorems and optimal error bounds for jarratt's iterative method

In the first part of this paper, we consider the Kantorovich-Ostrowski convergence theorem of a fourth order method which requires two evaluations of f′ and one of f for solving nonlinear equations. The convergence of the iteration is established under the following assumptions: Let f:D⊂K→K be C 4 on D with |f″(x)|≦M,D be a convex open domain |f″(x)−f″(y)|≦L|x−y| and |f (4)(x)|≦N for all x,y∊D. Assume that x 0∊D y 0 = u(x 0): = x 0−f(x 0)/f′(x 0), |f′(x 0)−l|≦ β, |y o−x o|≦μ, Here x n and y n are generated by the following schemes: In the second part, we show that in fact Jarratt's method is equivalent to Newton's method under optimal operator. Also we give an exact error constant and show that it cannot be improved.
JTT-130, a Novel Intestine-Specific Inhibitor of Microsomal Triglyceride Transfer Protein, Improves Hyperglycemia and Dyslipidemia Independent of Suppression of Food Intake in Diabetic Rats

We investigated the effects of JTT-130 on glucose and lipid metabolism independent of the suppression of feeding by comparing with pair-fed animals. Male Zucker diabetic fatty (ZDF) rats were divided into control, JTT-130 treatment, and pair-fed groups. The rats were fed with a regular powdered diet with or without JTT-130 as a food admixture for 6 weeks. We compared the effects on glucose and lipid metabolism in JTT-130 treatment group with those in pair-fed group. Results. Hyperglycemia in ZDF rats was prevented in both JTT-130 treatment and pair-fed groups, but the prevention in pair-fed group became poor with time. Moreover, reduction in plasma cholesterol levels was observed only in JTT-130 treatment group. JTT-130 treatment group showed improved glucose tolerance at 5 weeks after treatment and significant elevation of portal glucagon-like peptide-1 (GLP-1) levels. The hepatic lipid content in JTT-130 treatment group was decreased as compared with pair-fed group. Furthermore, pancreatic protection effects, such as an increase in pancreatic weight and an elevation of insulin-positive area in islets, were observed after JTT-130 treatment. Conclusions. JTT-130 improves hyperglycemia and dyslipidemia via a mechanism independent of suppression of food intake, which is ascribed to an enhancement of GLP-1 secretion and a reduction of lipotoxicity.
Shareable Technology Mash-Up for Situation Awareness in Catastrophic Events

This paper offers a descriptive account of the use of a shareable mash-up of technologies designed to create situation awareness during catastrophic events. In particular, we focus on the exploratory use of technologies for information aggregation and sharing between public and private sector entities during a national emergency simulation--National Level Exercise 2011. The goal of this research is to seek a proper way to integrate ubiquitous technologies such as Twitter, Google Earth Map, and Person Finder to share situation updates as well as monitor resource allocation during response to a catastrophic event. We implement an emergent use of micro syntaxes on feeds from Twitter to facilitate coordination of efforts among responding agencies. This paper concludes with a discussion of several implications for design based on our findings that may be beneficial to crisis management as well as other domains.
Aspirations, achievements and life satisfaction

A statistical model is formulated and tested empirically in an effort to evaluate observed differences in satisfaction levels as a function of relative differences in perceived aspirations and achievements of the individual. Data for testing the model were developed from personal interviews with a random sample of 1946 Oregon adults. Scores for two domains, public safety and income security satisfactions, were employed in this paper. Effects of three independent variables — an individual's sex, income level and age — also were tested. The results show that differences in domain satisfaction seem to occur through different processes, depending on the domain and the independent variable employed. The statistical tests reported provide some information on the theoretical formulation but additional measures are required to provide a more rigorous test of the model.
Beneficial Effect of Bilateral Pallidotomy on Gait Is Unproven

Siegel and Metman conclude that bilateral pallidotomy has a beneficial effect on walking speed. There are several difficulties with this conclusion. The authors compare the mean preoperative speed with the mean postoperative speed and show that the latter speed is twice the former. However, as stated in the article, there was a highly variable individual response. Comparing means may give a misleading picture since the mean is seriously affected by extreme values. The data of Figure 1 can be used to present a somewhat less optimistic result. Using the slopes of the lines connecting the preoperative and postoperative speeds, the 11 patients can be grouped as follows: 3 (27%) deteriorated, 1 (9%) was essentially unchanged, 4 (36%) had moderate improvement, and 3 (27%) had marked improvement. Thus, 36% of the patients showed no improvement or had deterioration. The clinical utility of any putative improvement is uncertain. For the 64% whose speed increased, it is not clear how the degree of improvement in walking speed translates into functional improvement. Is there a certain threshold below which an increase in walking speed does not result in functional improvement? Does the threshold (if it exists) vary with the baseline speed? Both seem likely. If so, the group with moderate improvement may not have gained any meaningful functional improvement. Furthermore, the variation in response may simply reflect a placebo effect. At the 1-month preoperative examination, patients were aware (especially after signing informed consent) that they faced a significant possibility of death or other major complications. At the 1-month postoperative examination, they not only knew they had survived, but if there was no additional disability from surgery, they could be hopeful that they might improve. Whose stride would not slow when heading toward the executioner and quicken after a reprieve?
Detection and identification of immobilized low-volatility organophosphates by desorption ionization mass spectrometry

Abstract Two desorption ionization mass spectrometry (MS) techniques – ultraviolet laser desorption/ionization (LDI) and desorption electrospray ionization (DESI) – have been used to detect and identify low-volatility organophosphates when deposited on surfaces or loaded into the pore volume of porous inorganic or polymeric organic powders. The insecticides malathion and dicrotophos were chosen for this study as simulants of low vapor pressure chemical warfare agents which are inherently difficult to detect directly by traditional methods. Both liquid and powdered forms of either insecticide were readily detected by LDI or DESI MS. LDI MS was performed on a miniaturized home-built time-of-flight (TOF) mass spectrometer and a commercial TOF/TOF instrument. For DESI MS, a home-built ion source was interfaced to a commercial quadrupole ion trap. In LDI, intact molecular ion signatures could be acquired by using an appropriate cationizing agent and powder additive in positive ion mode. Tandem MS was used to confirm the identity of each analyte based on the observed characteristic fragmentation pattern. In DESI, less than 100 pg of the liquid insecticides spotted on clean surfaces were detected, while detection limits for the powder-loaded preparations were lower than 1 μg. The effects of sample surface, salt additives, nanoparticle admixtures, and analyte solubility on the LDI and DESI MS sensitivity have been investigated as well.
Alcohol use before and during unwanted pregnancy

Background There is little information about pregnancy-related changes in alcohol use and factors contributing to changes among women with unwanted pregnancies. This study describes changes in alcohol use from before pregnancy recognition to during pregnancy and identifies important predictors of alcohol use severity among women with unwanted pregnancies. Methods Data are from the Turnaway Study of 956 women seeking pregnancy termination at 30 U.S. facilities between 2008 and 2010, some of whom were denied care because they were past the gestational limit of the facility where they were recruited and were still pregnant at the baseline interview, 1 week after termination seeking. Predictors of alcohol use severity (a latent variable) were identified. Results About 56% of the total sample reported any alcohol use the month before pregnancy recognition, with 23% reporting 6 or more drinks on an occasion. Among the total sample, 35% of those drinking before pregnancy recognition had quit and 20% had reduced 1 week after termination seeking. Among those denied terminations and still pregnant, 71% had quit and 14% had reduced. In a multivariate model predicting alcohol severity, younger age, still pregnant, 1 or more previous births, later gestation, childhood physical abuse, and marijuana and other drug use were associated with lower severity; having completed college, tobacco use, and recent physical violence were associated with higher severity. Conclusions The proportion of the total sample drinking before pregnancy recognition is similar to national samples of women of childbearing age, while the proportion binge drinking appears higher. Of women denied terminations, who were still pregnant, the proportion having quit is similar to other populations of pregnant women. More research is needed to examine whether pregnant women may be substituting alcohol for marijuana and other drugs. Interventions focusing on alcohol use severity during pregnancy may need to also focus on tobacco.
Sex differences in response to taste and postingestive consequences of sugar solutions.

Abstract Male and female rats, maintained on a 23 hr deprivation schedule, were offered solutions of water, 0.1% saccharin, 7% sucrose, 4% glucose, or 0.1% saccharin plus 4% glucose, during the daily 1 hr period of access to food pellets. The different solutions were selected to assess the effects of variations in taste and postingestive cues on the suppression of feeding behavior. The results show that male rats are virtually unaffected by the manipulation of taste factors, but consistently overrespond to the caloric value of the sugar solutions. Females are less likely to overrespond to the caloric consequences, but are more responsive than males to the taste properties.
Tumor vaccination against hepatoma: how does it work?

Fusion of BERH-2 rat hepatocellular carcinoma cells with activated B cells produced hybrid cells that lost their tumorigenicity and became immunogenic. Syngeneic rats injected with BERH-2-B hybrid cells became resistant to challenge with parental BERH-2 cells, and rats with established BERH-2 hepatomas were cured by subsequent injection of BERH-2-B cells. Both CD4 and CD8+ cells were essential for the induction of protective immunity; however, only CD8+ cells were required for the eradication of BERH-2 tumors. The generation of hybrid tumor cells that elicit antitumor immune responses may be a useful strategy for cancer immunotherapy.
Scaffolding Preservice Teachers' Evaluation of Children's Science Literature: Attention to Science-Focused Genres and Use

The use of an inquiry framework to support the development of learners' scientific literacy has been supported by research on learning in science and advocated by the major science standards and policy documents. To fully engage in inquiry, however, a wide range of tools, including both activities and texts, must be employed. The successful integration of text materials requires the selection of suitable texts. This, in turn, requires an in-depth understanding of the types of science books available and their potential uses within an inquiry framework. To support preservice teachers' development of these understandings, I examined the criteria they typically employ when evaluating texts in contextualized and uncontextualized settings. In these settings, students attended primarily to visual characteristics of texts or exhibited their limited understandings of science content and text use. These results were used to develop an evaluation framework that emphasizes use in inquiry over other typical evaluation criteria.
Hydrogen bonding in the crystal structure of the tetrasaccharide stachyose hydrate: a 1:1 complex of two conformers

Abstract The crystal structure of stachyose hydrate, O -α- d -galactopyranosyl-(1 → 6)- O -α- d -galactopyranosyl-(1 → 6)-α- d -glucopyranosyl β- d -fructofuranoside tetrahydrate, has been refined using X-ray data at 119 K. The crystal structure is a 1:1 complex of conformers which differ in the fructofuranosyl and glucopyranosyl residues. Each conformer has an associated hydrogen-bond structure which includes different sites for the water molecules. When superimposed in the crystal, this gives rise to two sites of 0.5 occupancy for one carbon and one oxygen atom of the fructofuranose component, and for three oxygen atoms of the glucopyranose component. The corresponding three carbon atoms of the glucopyranose component have anomalous thermal motion parameters. The four water molecules are distributed over nine sites, six with occupancy 0.5, two with occupancy 0.4, and one with occupancy 0.2. Four of the water sites are associated with one conformer, and four with the other. The hydrogen bonding includes infinite chains which are linked to form irregular ribbons, extending in the direction of the a axis. All hydroxyl, ring, and linkage oxygen atoms are involved in the hydrogen bonding, which includes two-centered, three-centered, and four-centered hydrogen bonds.
Does ‘Ought’ Imply ‘Can’ from an Epistemic Point of View?

In this paper, I argue that the “Ought Implies Can” (OIC) principle, as it is employed in epistemology, particularly in the literature on epistemic norms, is open to counterexamples. I present a counterexample to OIC and discuss several objections to it. If this counterexample works, then it shows that it is possible that S ought to believe that p, even though S cannot believe that p. If this is correct, then OIC, considered from an epistemic point of view, is false, since it is supposed to hold for any S and any p.
Degree of superhelicity of covalently closed cyclic DNA's from Escherichia coli☆

Abstract The degree of superhelicity of four covalently closed double-stranded cyclic DNA's from Escherichia coli has been measured by determining the sedimentation coefficients of the DNA's at 20 °C in 3 m -CsCl-0.01 m -sodium EDTA (pH 8), as a function of ethidium bromide concentration in the sedimentation medium. The number of superhelical turns is −8.5 for an E. coli 15 plasmid DNA (1.45 megadalton), −19 for φ 174 RFI (3.4 megadalton), −100 for λ b2b5c DNA (26 megadalton), −136 for λcI857 DNA (33 megadalton) from sensitive cells, and −155 for λcI857 DNA from superinfected immune cells. The superhelical densities (number of superhelical turns per ten base pairs) of these species are −0.039, −0.037, −0.026, −0.027 and −0.031, respectively. Although there is a 20-fold range in the number of superhelical turns for these DNA's, the superhelical density is constant within a factor of 1.5. For λb2b5c DNA, the degree of superhelicity of the intracellularly closed species is identical for samples isolated from cells infected in the presence or absence of 30 μg of chloramphenicol/ml. It appears that closed cyclic λb2b5c DNA isolated from cells infected at 39 °C is slightly less twisted than the same DNA isolated from cells infected at 29 °C.
Phase evolution in boron nitride thin films

Boron nitride (BN) thin films were deposited on monocrystalline Si(100) wafers using electron beam evaporation of boron with simultaneous bombardment by nitrogen and argon ions. The effect of film thickness on the resultant BN phase was investigated using Fourier transform infrared (FTIR) spectroscopy and high resolution transmission electron microscopy (HRTEM). These techniques revealed the consecutive deposition of an initial 20 A thick layer of amorphous BN, 20–50 A of hexagonal BN having a layered structure, and a final layer of the polycrystalline cubic phase. The growth sequence of the layers is believed to result primarily from increasing biaxial compressive stresses. Favorable surface and interface energy and crystallographic relationships may also assist in the nucleation of the cubic and the hexagonal phases, respectively. The presence of the amorphous and hexagonal regions explains why there have been no reports of the growth of 100% cubic boron nitride on Si.
Specific-primer-directed DNA sequencing using automated fluorescence detection

Abstract Automated fluorescence-based DNA sequence analysis offers the possibility to undertake very large scale sequencing projects. Directed strategies, such as the specific-primer-directed sequencing approach ('gene walking'), should prove useful in such projects. Described herein is a study involving the use of this approach in conjunction with automated fluorescence detection on a commercial instrument (ABI 370A DNA sequencer). This includes procedures for the rapid chemical synthesis and purification of labeled primers, the design of primer sequences that are compatible with the commercial analysis software, and automated DNA sequence analysis using such primers. A set of four fluorophore-labeled primers can be reliably synthesized in a twenty-four hour period, and greater than 300 nucleotides of analyzed new sequence obtained using this set in an additional twenty-four hours. Scale-up of these procedures to take advantage of the full capabilities of the sequencer is, at present, too slow and costly to be suitable for routine sequencing, and therefore the use of specific-primers is best suited to the closure of gaps in extended sequence produced using random cloning and sequencing strategies.
Factors That Motivate Healthy Adults to Participate in Phase I Drug Trials

To determine the primary motivational factors for Phase I trial participation, this study tested the following hypotheses: the primary motivation for young and elderly volunteers to participate in their first Phase I trial is money; the primary reason young subjects participate in subsequent trials is money; the primary reason elderly volunteers participate in subsequent trials is social interaction; the primary reason healthy people do not participate in a second Phase I trial is schedule conflict. Twenty-eight young subjects (mean age 28 years) and 28 elderly subjects (mean age 72 years) were surveyed via a 15-item mailed questionnaire. Study results indicate that money is the primary reason young and elderly volunteers participate in their first drug study and the primary reason young volunteers participate in subsequent studies. Altruism is a primary motivator for elderly participation in more than one study and schedule conflicts are the main reason people do not participate in subsequent trials
Loss of epithelial polarity: a novel hypothesis for reduced proximal tubule Na+ transport following ischemic injury.

Ischemia results in the marked reduction of renal proximal tubule function which is manifested by decreased Na+ and H2O reabsorption. In the present studies the possibility that altered Na+ and H2O reabsorption were due to ischemia-induced loss of surface membrane polarity was investigated. Following 15 min of renal ischemia and 2 hr of reperfusion, proximal tubule cellular ultrastructure was normal. However, abnormal redistribution of NaK-ATPase to the apical membrane domain was observed and large alterations in apical membrane lipid composition consistent with loss of surface membrane polarity were noted. These changes were associated with large decreases in Na+ (37.4vs. 23.0%,P<0.01) and H2O (48.6vs. 36.9%,P<0.01) reabsorption at a time when cellular morphology, apical Na+ permeability, Na+-coupled cotransport, intracellular pH and single nephron filtration rates were normal. We propose that the abnormal redistribution of NaK-ATPase to the apical membrane domain is in part responsible for reduced Na+ and H2O reabsorption following ischemic injury.
MO‐A‐301‐01: Essentials of CT Image Reconstruction: 3D Filtered Backprojection

The mathematical basis for CTimage reconstruction is over a century old, and its practical implementation in medicine is now entering its fifth decade. It presents one of the most prevalent and adaptable of medical imaging modalities, with applications ranging from diagnosticimaging to image‐guided interventions, radiotherapy simulation, and preclinical imaging. Not only is it the mainstay of a broad spectrum of diagnostic and interventional procedures, CT — and its more recent extension to cone‐beam CT — is in the midst of important innovations aiming to reduce dose, improve image quality, and open new areas of application. Such innovations include new detector technologies (e.g., multi‐detector CT and flat‐panel detector cone‐beam CT), new reconstruction algorithms (e.g., iterative, statistical, and model‐based reconstruction approaches), and new physical embodiments better suited to novel applications (e.g., breast CT, C‐arm CT, and dedicated scanners for other specialty imaging applications). The basic and most prevalent method of CTimage reconstruction has been filtered backprojection (FBP), with important extensions to fully 3D FBP for cone‐beam CT. This session provides a summary of the basic principles of this reconstruction method, covering the basic mathematical principles and focusing on practical aspects of real implementation. Essentials of the basic algorithm include projection data pre‐processing, geometric calibration, filtering, backprojection, and extensions to reduce image artifacts. Related issues of image quality and artifacts are also addressed — for example, how parameters of the reconstruction algorithm affect spatial resolution, noise, and prospects for radiationdose reduction. Resources for learning and open‐source software implementations are summarized. Some of the new research and applications of CT now underway in the medical physics community are summarized, focusing on challenges and opportunities for novel image reconstruction techniques, dose reduction, and new applications. Learning Objectives: 1. Understand the basic algorithmic components of filtered backprojection reconstruction in CT. 2. Understand some of the educational and open‐source research resources that exist regarding CTreconstruction. 3. Understand how parameters of the reconstruction algorithm affect CTimage quality. 4. Learn about the reconstruction activities underway in the AAPM and research community.
Expression of mouse rod photoreceptor cGMP phosphodiesterase γ subunit in bacteria

Abstract We expressed the γ subunit of mouse rod photoreceptor cGMP phosphodiesterase (PDE) in the bacterial pGEX-2TK expression vector which produces a cleavable 40 kDa fusion protein. The fusion protein can be isolated in a one step procedure by affinity chromatography on glutathione beads. The yield of purified fusion protein is approximately 10 mg from 1 liter of bacterial culture, or about 3 mg of PDEγ, equivalent to the PDEγ content of approximately 200,000 mouse retinas. Both the fusion protein and the cleaved PDEγ, to which a short kinase domain remains attached, are biologically active, inhibiting activated PDE in a manner comparable to native PDEγ. Immobilized PDEγ binds transducin α subunit charged with GTP, PDE α and β subunits, and, unexpectedly, arrestin (S-antigen).
A high-resolution morphogenetic map of the second-leg basitarsus inDrosophila melanogaster.

The lineages of cells on the second-leg basitarsus ofDrosophila melanogaster were analyzed by examining gynandromorphs andMinute mosaics. Bracts lie proximal to bristles on the adult basitarsus, yet bract precursor cells were found to originate lateral to bristle precursor cells. In 6 of the 8 longitudinal rows of bristles on this segment, the bract cells arise ventral to the bristle cells; in the others they arise dorsally. The lateral cell origins are interpreted as reflecting a pattern of lateral cell movements associated with evagination of the leg disc. An unusual discrepancy was observed in the relative frequencies of male vs. female bracts and bristles in gynandromorphs. The discrepancy suggests that there is a cell-autonomous sexual difference in either the time at which cells begin moving during evagination or the speed with which they move.
Argininosuccinate lyase deficiency: longterm outcome of 13 patients detected by newborn screening.

Abstract Argininosuccinate lyase deficiency is a urea cycle disorder which can present in the neonatal period with hyperammonemic encephalopathy, or later in childhood with episodic vomiting, growth and developmental delay. Abnormal hair, hepatomegaly, and hepatic fibrosis are unique features of this disorder. Twelve patients with argininosuccinate lyase deficiency were ascertained between 4 and 6weeks of age by urine amino acid screening. One infant in a previously identified family was diagnosed shortly after birth. Diagnosis was confirmed by enzyme assay in red blood cells and/or skin fibroblasts. At the time of last follow-up, patients had been followed for 13–33years. All patients were asymptomatic at detection, 7 had slightly increased blood ammonia, and all were initially treated with low-protein diet. Utilization of 14 C-citrulline by intact skin fibroblasts measured by 14 C incorporation into macromolecules was 74–135% of the control mean for 7 of the 8 patients studied. Nine patients had normal development, 4 had learning disability, 6 had EEG abnormalities, 3 had seizure disorder. None had any episodes of hyperammonemic coma. None had hepatomegaly. Patients detected by screening had higher enzyme activity measured by the 14 C-citrulline incorporation assay than comparison groups of patients with neonatal-onset and with late-onset detected by clinical disease. The ability to utilize 14 C-citrulline by intact fibroblasts seems to correlate with clinical outcome and may have prognostic value. It is likely that early diagnosis and treatment contributed to the relatively mild clinical course of the study group.
Learning Object-Oriented Programming in Python: Towards an Inventory of Difficulties and Testing Pitfalls

We report a small yet detailed study where we recorded students completing an object-oriented programming exercise in the context of a CS2 course using Python. All students struggled while completing the assignment, most notably experiencing difficulties with parameters and referencing elements with object-dot notation. While previous research has identified these areas as troublesome for novice programmers, our analysis suggests that parameters and reference specifications are particularly critical prerequisites for learning advanced object-oriented concepts with the Python programming language. Given our findings, we recommend extensive practice with parameter passing and object-dot notation before addressing advanced object-oriented concepts in a Python course.
Computer solutions for studying correlations between solar magnetic fields and Skylab X-ray observations.

A method is described which correlates the NASA-Marshall Space Flight Center (MSFC) Image Data Processing System (IDAPS) and MSFC magnetograph data to X-ray and H-alpha observations from the Skylab mission. Solutions of Laplace's equation in three dimensions, based on the magnetograph data, are convolved with observed X-ray and H-alpha regions. Matched filtering (template matching) provides a best fit of the observed X-ray regions to the computed total magnetic vector magnitude between 10,000 and 15,000 km above the photosphere.
How Do We Ensure that Everyone Graduates? An Integrated Prevention and Tiered Intervention Model for Schools and Districts.

Schools with large numbers of students falling off the graduation path need comprehensive reforms that create a solid foundation of high-quality instruction and positive behavioral supports for all students. They also need data-driven response systems that provide targeted and intensive interventions for students who need additional academic and social supports. This article offers a systematic plan for dropout prevention at the district and school levels that integrates research-based recommendations into a coherent, three-tiered model. The model provides a way to coordinate all types of interventions and replace the patchwork of fragmented programs that often allows students to fall through the cracks.
Sources of fine particulate sulfate in New York

Abstract Daily PM2.5 sulfate measurements are reported for July 2001 through June 2002 from three New York State sites that were a part of the New York Supersite Program. The sampling sites were located at Queens, Pinnacle State Park, and Whiteface Mountain. Quarterly mean sulfate concentrations at these sites were respectively; 5.05, 5.08, and 3.14 μg/m3 during July–September (QIII); 2.84, 2.26, and 1.40 μg/m3 during October–December (QIV); 2.71, 2.39, and 1.55 μg/m3 during January–March (QI); and 4.17, 4.52, and 2.15 μg/m3 during April–June (QII). Although the sites are separated by several hundred kilometers and surrounded by highly varied population densities, their sulfate concentrations have very similar patterns. These data show that sulfate concentrations over broad regions of the Northeast are correlated. Backward air trajectories were used to evaluate the regional sources of sulfate impacting these sites. The highest sulfate concentrations at all three sites were associated with air masses that pass through the Ohio River Valley and the area around the Great Lakes Basin. Moderately high concentrations at Pinnacle and Queens were also associated with air flow through the Mid-Atlantic states. In addition, we used air trajectories to estimate local versus transported components. On an annual basis, 44–55% of the sulfate at Queens and 60% at Whiteface and Pinnacle was transported.
Regulation of Glyoxysomal Enzyme Expression in Maize

The activity levels of three glyoxysomal enzymes (catalase, isocitric lyase, and malate synthase) were measured in the scutellum following germination of the inbred lines W64A, R6-67, and A16. In W64A, as in most maize lines examined, germination was accompanied by a rapid and synchronous increase in the activities of all three enzymes, and reached a peak at about day 4 and declined thereafter. In R6-67, catalase activity continues to increase past day 4 and reaches its highest activity level on later days. In A16, catalase activity is very low due to the lack of expression of the Cat2 gene. Despite these significant differences in catalase expression, the levels of the other two glyoxysomal enzymes did not differ in these inbred lines. Artificial inhibition of catalase in W64A by exogenous application of 10–4 M aminotriazole did not inhibit germination, nor did it alter the levels of the other two glyoxysomal enzymes. Similarly, application of 10–4 M itaconate to W64A seeds inhibited the appearance of isocitric lyase, but did not inhibit germination or alter the levels of malate synthase or catalase. Comparative cell fractionation and immunological studies were conducted with W64A and A16 and their microbodies were observed under the electron microscope. Cell fractionation studies were also conducted with W64A seeds germinated in the presence of aminotriazole or itaconate. Thus, our results suggest that the expression of these three glyoxysomal enzymes is not regulated coordinately in the maize scutellum.
Modelling security in the maritime supply chain using knowledge constructs

The purpose of this research is to develop a decision process and modelling framework for port and ocean carrier selection that incorporates and quantifies knowledge elements and knowledge practices concerning global supply chain security. Ocean carrier selection is considered in concert with port selection to augment the integrated supply chain process and its synergistic benefits to performance. Knowledge is quantified in this approach with a scoring mechanism that compares security-related features of a particular operation to best practice in that area. These scores are then combined with other performance attributes in a second step that employs the analytic hierarchy process. This research demonstrates that knowledge elements and practices that are essentially qualitative in nature may be utilised in concert with traditional measures in a quantitative modelling process that improves supply chain design. Managers responsible for choosing security-aware seaports and ocean carriers may find this model useful for addressing multiple criteria of both a quantitative and qualitative nature.
CYTOKINE-MEDIATED NEURONAL APOPTOSIS

Cytokines have been reported to induce neuronal injury via the free radical nitric oxide (NO); however, the precise mechanism underlying cytokine-mediated neurotoxicity is unclear. We investigated the hypothesis that cytokine-mediated neurotoxicity in primary cultures of human fetal neurons occurs via an apoptotic mechanism triggered by NO. Treatment of mixed neuronal/glial cell cultures with interferon (IFN)-γ plus interleukin (IL)-1β for 13 days induced a high output of NO accompanied by marked neuronal loss. The NO synthase inhibitor N-monomethyl-l-arginine (NMMA) significantly attenuated cytokine-induced neuronal loss, confirming the involvement of NO. Cytokine-mediated neuronal injury was accompanied by morphologic changes and a DNA fragmentation pattern consistent with apoptosis. Treatment of neuronal cell cultures with NMMA protected against cytokine-mediated apoptotic death. These findings, using primary human neuronal cell cultures, support the hypothesis that cytokine-mediated neurotoxicity involving NO proceeds via an apoptotic mechanism. These findings could lead to the development of new therapies for neurodegenerative diseases involving glia, cytokines, and NO. © 1997 Elsevier Science Ltd. All rights reserved