cssi/SciSciGPT-SciSciNet huggingface dataset:
Kinetic mechanism and nucleotide specificity of NADH peroxidase

NADH peroxidase is a flavoprotein isolated from Streptococcus faecalis which catalyzes the pyridine nucleotide-dependent reduction of hydrogen peroxide to water. Initial velocity, product, and dead-end inhibition studies have been performed at pH 7.5 and support a ping-pong kinetic mechanism. In the absence of hydrogen peroxide, both transhydrogenation between NADH and thioNAD, and isotope exchange between (/sup 14/C)NADH and NAD, have been demonstrated, although in both these experiments, the maximal velocity of nucleotide exchange was less than 1.5% the maximal velocity of the peroxidatic reaction. We propose that NADH binds tightly to both oxidized and two-electron reduced enzyme. NADH oxidation proceeds stereospecifically with the transfer of the 4S hydrogen to enzyme, and then, via exchange, to water. No primary tritium kinetic isotope effect was observed, and no statistically significant primary deuterium kinetic isotope effects on V/K were determined, although primary deuterium kinetic isotope effects on V were observed in the presence and absence of sodium acetate. NADH peroxidase thus shares with other flavoprotein reductases striking kinetic, spectroscopic, and stereochemical similarities. On this basis, we propose a chemical mechanism for the peroxide cleaving reaction catalyzed by NADH peroxidase which involves the obligate formation of a flavinperoxide, and peroxo bond cleavage by nucleophilicmore » attack by enzymatic dithiols.« less
Evaluation of separation and purification processes in the antibiotic industry. Scientific note.

Antibiotic production is a complex capital intensive process, which divides naturally into two segments, fermentation and separation/purification. The separation and purification section is very large as a result of the number of processing steps required (up to 60) and the need to purify and recycle large quantities of organic solvents. Separation and purification is not generic within the antibiotic industry. Not only does each individual antibiotic require a different separation process, but also there are many different separation schemes in use for the same antibiotic. Much research is currently in progress on three relatively new separation techniques on a commercial level, which may lead to substantial reductions in the complexity of the process; chromatography (both conventional preparative HPLC and annular chromatography), supercritical extraction, and various membrane processes.
Salt clean-up procedure for the determination of domoic acid by HPLC.

Domoic acid (DA) was first reported in mussels from Prince Edward Island, Canada, in 1987. It reappeared in anchovies and pelicans from Monterey Bay, California, in 1991. Later that year, domoic acid was found in razor clams and Dungeness crabs along the Washington and Oregon coasts. Since the initial outbreak, a variety of analytical methods for the detection of this neurotoxin have been developed. Here, we describe a modification to the solid phase extraction (SPE) clean-up step in Quilliam's HPLC-UV method (1991: NRCC No. 33001). The standard 10% acetonitrile (MeCN) wash and 0.5M ammonium citrate buffer (ACB) in 10% MeCN (pH = 4.5) eluting solution have been replaced with a 0.1 M sodium chloride (NaCI) in 10% MeCN wash and a 0.5M NaCI in 10% MeCN eluting solution. This modification allows the analysis to work equally well on both clam and crab viscera and meat. Chromatograms of visceral samples no longer contain interfering or late eluting peaks; and all Chromatograms are free of the large solvent peak tailing associated with the ACB eluent. The newly modified method allows for an improved and more versatile domoic acid analysis. © 1994 Wiley-liss, Inc.
Thin Bio-Artificial Tissues in Plane Stress: The Relationship between Cell and Tissue Strain, and an Improved Constitutive Model

Constitutive models are needed to relate the active and passive mechanical properties of cells to the overall mechanical response of bio-artificial tissues. The Zahalak model attempts to explicitly describe this link for a class of bio-artificial tissues. A fundamental assumption made by Zahalak is that cells stretch in perfect registry with a tissue. We show this assumption to be valid only for special cases, and we correct the Zahalak model accordingly. We focus on short-term and very long-term behavior, and therefore consider tissue constituents that are linear in their loading response (although not necessarily linear in unloading). In such cases, the average strain in a cell is related to the macroscopic tissue strain by a scalar we call the “strain factor”. We incorporate a model predicting the strain factor into the Zahalak model, and then reinterpret experiments reported by Zahalak and co-workers to determine the in situ stiffness of cells in a tissue construct. We find that, without the modification in this article, the Zahalak model can underpredict cell stiffness by an order of magnitude.
The benefits and challenges of using educational game projects in an undergraduate software engineering course

Devising team projects for an introductory software engineering course can be a challenge for educators. A balance between an engaging project that is complex enough for the team to complete in the timeframe of the course is required. This paper describes the experiences of using an educational game as the team project in a 10-week introductory software engineering course for second-year undergraduates. The motivation for the project and the project itself will be presented. Benefits of using a game project existing, but the challenges of using a game project were perceived to be high by some instructors. The reflection of the experience is meant to help other instructors to find the right fit for a game project in their introductory course.
A morphologic study of bronchus-associated lymphoid tissue in turkeys

Bronchus-associated lymphoid tissue (BALT) in normal turkeys of ages 1 day and 1, 2, 3, 4, 8, and 18 weeks was examined by light microscopy and by scanning and transmission electron microscopy. Turkey BALT resembled other mucosa-associated lymphoid tissues; it was made up of a population of lymphocytes covered by a specialized epithelium different from typical pseudostratified ciliated columnar bronchial epithelium. There were distinct age-related differences in BALT structure. Bronchus-associated lymphoid nodules were larger and more numerous in older turkeys. In 1-day- to 2-week-old turkeys, the primary cell type of BALT epithelium was nonciliated cuboidal; in 2-week old turkeys it was squamous; and in turkeys older than 4-weeks of age, the epithelium was primarily ciliated columnar. In 1- to 4-week old turkeys, large numbers of intraepithelial lymphocytes disrupted the normal organization of the epithelium. In older turkeys, epithelial and lymphoid cells were in discrete compartments separated by connective tissue. Lymphocytes in 1-day-old turkeys were found in loose aggregates around venules and within the epithelium. In 1-week old turkeys, lymphocytes were organized into compartments of morphologically similar cells. By 3-weeks of age, lymphocytes were present in distinct germinal centers. Epithelial cells of BALT did not have large numbers of apical vesicles and thus were not structurally specialized for antigen uptake by endocytosis. However, the epithelial barrier appeared to be disrupted over lymphoid nodules, suggesting that antigen would be readily available to lymphocytes and phagocytes in BALT. Age-related differences in turkey BALT structure may have functional consequences with respect to the respiratory immune response.
Serum esterase genetics in rats: Two new alleles at Es-2, a new esterase regulated by hormonal factors, and linkage of these loci to the Ag-C blood group locus

Two new alleles at the Es-2 locus are described which determine electrophoretic variants of serum esterases of rats. A new esterase protein is described which is detectable in sera of sexually mature females of the appropriate genotype. Evidence is presented for genetic linkage between the Ag-C blood group locus and Es-1, Es-2, and the locus controlling the sex-influenced protein. Since the Ea-1 blood group locus of mice is linked to four esterase loci, it is suggested that Ag-C is the rat homologue of the mouse Ea-1 locus.
Robust estimation of road friction coefficient using lateral and longitudinal vehicle dynamics

Vehicle active safety systems stabilise the vehicle by controlling tyre forces. They work well only when the tyre forces commanded by the safety systems are within the friction limit. Therefore, knowledge of the tyre/road friction coefficient can improve the performance of vehicle active safety systems. This study presents four methods to estimate the friction coefficient based on four different excitation conditions: medium lateral excitation, large lateral excitation, small longitudinal excitation, and large longitudinal excitation. For the lateral excitation cases, the estimation is based on vehicle lateral/yaw dynamics and Brush tyre model, whereas for the longitudinal excitation cases, the estimation basis is the relationship between the tyre longitudinal slip and traction force. These four methods are then integrated to increase the working range of the estimator and to improve robustness. The performance of the integrated estimation algorithm is verified through experimental data collected on several surface conditions.
Structure and function of mammalian DNA ligases

Abstract DNA joining events are required for the completion of DNA replication, DNA excision repair and genetic recombination. Five DNA ligase activities, I–V, have been purified from mammalian cell extracts and three mammalian LIG genes, LIG1 , LIG3 and LIG4 , have been cloned. During DNA replication, the joining of Okazaki fragments by the LIG1 gene product appears to be mediated by an interaction with proliferating cell nuclear antigen (PCNA). This interaction may also occur during the completion of mismatch, nucleotide excision and base excision repair (BER). In addition, DNA ligase I participates in a second BER pathway that is carried out by a multiprotein complex in which DNA ligase I interacts directly with DNA polymerase β. DNA ligase IIIα and DNA ligase IIIβ, which are generated by alternative splicing of the LIG3 gene, can be distinguished by their ability to bind to the DNA repair protein, XRCC1. The interaction between DNA ligase IIIα and XRCC1, which occurs through BRCT motifs in the C-termini of these polypeptides, implicates this isoform of DNA ligase III in the repair of DNA single-strand breaks and BER. DNA ligase II appears to be a proteolytic fragment of DNA ligase IIIα. The restricted expression of DNA ligase IIIβ suggests that this enzyme may function in the completion of meiotic recombination or in a postmeiosis DNA repair pathway. Complex formation between DNA ligase IV and the DNA repair protein XRCC4 involves the C-terminal region of DNA ligase IV, which contains two BRCT motifs. This interaction, which stimulates DNA joining activity, implies that DNA ligase IV functions in V(D)J recombination and non-homologous end-joining of DNA double-strand breaks. At the present time, it is not known whether DNA ligase V is derived from one of the known mammalian LIG genes or is the product of a novel gene.
SPECIALIZATION AND RESOURCE TRADE: BIOLOGICAL MARKETS AS A MODEL OF MUTUALISMS

Most ecological theory suggests that the conditions that would give rise to the evolution of mutualisms are rare. In contrast, empirical evidence suggests that mutualisms are common. Thus, there appears to be a need for additional theory to describe conditions under which mutualisms may evolve. Furthermore, there is a need for theory to predict the conditions under which we expect interactions to remain mutualistic once established. We adopt a biological market approach to present a model for the evolution of resource exchange mutualisms, using the relationship between plants and mycorrhizal fungi as an example. We apply the economic theory of relative advantage to investigate the conditions under which species ought to specialize and trade. A simple economic analogy demonstrates that, in a two-resource model, a species that is relatively efficient at acquiring one resource would benefit from specialization on acquisition of that resource accompanied by trade for the other resource. The theory of relative advantage extends this prediction to show that specialization and trade confer an advantage even for species that are relatively poor resource competitors for both resources. Under the assumptions of our model, we show that two species ought to specialize in the acquisition of one resource and trade for a second resource as long as each species perceives different relative acquisition costs for the two resources. We also describe the conditions under which changing resource availabilities will benefit, or harm, both partners in a mutualism. We predict conditions conducive to mutualisms to occur when the costs of resource exchange are low, the opportunity to ensure fair trade is high, or the cost of tolerating cheaters is low. Market models such as ours may help to explain the conditionality often observed in mutualisms.
Simulation-based teaching to improve cardiovascular exam skills performance among third-year medical students.

Background: Evidence supports the need for improvement in cardiac physical examination skills training. Purpose: This study evaluates whether the addition of simulation offers added benefit over training utilizing standardized patients only. Methods: All 124 third-year students who completed the required clerkship in one academic year received cardiac examination skills training utilizing a standardized patient and a cardiac simulator. The control group, comprising 281 students from 2 previous academic years, received training utilizing a standardized patient only. All students’ physical exam skills were assessed in an objective structured clinical examination. Results: Students trained with cardiac simulation performed significantly better than the control group in all 5 cardiac skills. The number of students who correctly performed all 5 cardiac exam skills increased significantly (p= .004). Pulmonary exam skills were unchanged. Conclusion: The use of simulation in addition to standardized patient teach...
DNA methylation and histone acetylation patterns in cultured bovine fibroblasts for nuclear transfer.

Evidence indicates that failure of nuclear transfer (NT) embryos to develop normally can be attributed, at least partially, to the use of a differentiated cell nucleus as the donor karyoplast. It has been hypothesized that blastocyst production and development to term of cloned embryos may differ between population doublings (PDs) of the same cell line as a consequence of changes in DNA methylation and histone acetylation patterns during in vitro culture. The objective of this study was to determine gene expression patterns of the chromatin remodeling proteins DNA methyltransferase-1 (Dnmt1), methyl CpG binding protein-2 (MeCP2), and histone deacetyltransferse-1 (HDAC1), in addition, to measuring levels of DNA methylation and histone acetylation of bovine fibroblast cells at different PDs. Bovine fibroblast cell lines were established from four 50-day fetuses. Relative levels of Dnmt1, MeCP2, HDAC1, methylated DNA, and acetylated histone were analyzed at PDs 2, 7, 15, 30, 45, and 70. RNA levels of Dnmt1, HDAC1, and MeCP2 were examined using Q-PCR. Global levels of methylated DNA and acetylated histone were determined by incubation of fixed cells with an anti-5-methylcytidine and anti-acetyl-histone H3 antibody, respectively. Cells were labeled with a second antibody, counter-stained with propidium iodide and analyzed by flow cytometry. These data demonstrate that chromatin remodeling protein mRNAs involved in epigenetic modifications are altered during in vitro culture. Methylated DNA and acetylated histone patterns of in vitro cells change with time in culture. Subsequent use of these cells for NT will provide insight as to how these epigenetic modifications affect reprogramming. Mol. Reprod. Dev. 74: 1514–1524, 2007. © 2007 Wiley-Liss, Inc.
Sleep Deprivation in Social Phobia and Generalized Anxiety Disorder

Abstract Background: Sleep deprivation has been shown to improve depressive symptoms in some patients with major depressive disorder, but it has not been tested in patients with generalized anxiety disorder (GAD) or social phobia (SP). Methods: To determine if sleep deprivation altered anxiety or depressive symptoms in patients with GAD ( n = 7) or SP ( n = 8), we sleep deprived patients and normal controls ( n = 18) for one night. Results: On one measure of anxiety, GAD patients improved compared with controls, but there were otherwise no significant change differences between controls and SP or GAD patients. Conclusions: The lack of benefit is consistent with previous findings that sleep deprivation provides no benefit to patients with other anxiety disorders. Sleep deprivation may be a biological intervention that distinguishes anxiety from affective disorders.
GAO Report warns of NASA budget concerns

When he takes the office of vice-president next month, Al Gore (D-Tenn.) will also step into the chairmanship of the National Space Council. He brings to this position knowledge of the nation's space program, gained as chairman of the Senate Commerce Subcommittee on Science, Technology and Space.
A copula approach to assessing Granger causality

In neuroscience, as in many other fields of science and engineering, it is crucial to assess the causal interactions among multivariate time series. Granger causality has been increasingly used to identify causal influence between time series based on multivariate autoregressive models. Such an approach is based on linear regression framework with implicit Gaussian assumption of model noise residuals having constant variance. As a consequence, this measure cannot detect the cause-effect relationship in high-order moments and nonlinear causality. Here, we propose an effective model-free, copula-based Granger causality measure that can be used to reveal nonlinear and high-order moment causality. We first formulate Granger causality as the log-likelihood ratio in terms of conditional distribution, and then derive an efficient estimation procedure using conditional copula. We use resampling techniques to build a baseline null-hypothesis distribution from which statistical significance can be derived. We perform a series of simulations to investigate the performance of our copula-based Granger causality, and compare its performance against other state-of-the-art techniques. Our method is finally applied to neural field potential time series recorded from visual cortex of a monkey while performing a visual illusion task.
In search of the elusive benign cystic ovarian teratoma: Application of the ultrasound “tip of the iceberg” sign

The benign cystic ovarian teratoma (dermoid) has distinctive ultrasonic features that differentiate it from other adnexal masses. The most frequent sign is the presence of highly reflective irregular solid components within a fluid-conentaining adnexal mass. In vitro scans of surgical specimens have shown that the strongly reflective echo pattern is caused by the hair and sebum within the dermoid. Calcium is often sparse or absent. Acoustic shadowing from the hair may totally obscure the back wall of a large, clinically evident mass; hence the term “tip of the iceberg” sign. Recognition of this sign reduces the possibility of a false negative interpretation and confusion with a “bowel gas pattern.”
Quinine as a chiral additive in nonaqueous capillary zone electrophoresis

Quinine was used as a chiral additive in nonaqueous capillary zone electrophoresis. The separation buffer consisted of ammonium acetate and quinine in methanol. Quinine was able to enantioresolve a number of N-3,5-dinitrobenzoylated amino acids as well as (±)-1,1′-binaphthyl-2,2′diyl hydrogen phosphate and N-[1-(1-naphthyl)ethyl]phthalamic acid. Enantioresolution deteriorated as the concentration of ammonium acetate was increased but improved with the addition of acetic acid. Chiral recognition seems to arise through an ion-pairing mechanism. © 1996 John Wiley & Sons, Inc.
Clinical Relevance and Management of Drug‐Related QT Interval Prolongation

Much attention recently has focused on drugs that prolong the QT interval, potentially leading to fatal cardiac dysrhythmias (e.g., torsade de pointes). We provide a detailed review of the published evidence that supports or does not support an association between drugs and their risk of QT prolongation. The mechanism of drug-induced QT prolongation is reviewed briefly, followed by an extensive evaluation of drugs associated with QT prolongation, torsade de pointes, or both. Drugs associated with QT prolongation are identified as having definite, probable, or proposed associations. The role of the clinician in the prevention and management of QT prolongation, drug-drug interactions that may occur with agents known to affect the QT interval, and the impact of this adverse effect on the regulatory process are addressed.
A theoretical analysis of acoustic microscopy with converging acoustic beams

A theoretical analysis is carried out to synthesize acoustic material signatures (AMS) of solid plates immersed in water. The distinctive feature of this analysis is that it avoids three major simplifying assumptions of the presently available techniques, which are, paraxial approximation, assumption of perfect reflection and Gaussian summation of the incident field. Presently available techniques can avoid some but not all of these simplifying assumptions for computing the AMS. In this paper the analysis is carried out for lowfrequency acoustic waves generated by a cylindrical transducer without a lens rod. Reasons for these changes in the conventional acoustic microscope geometry is given. The AMS is synthesized for an aluminium plate in presence as well as in absence of water on its one side. As expected a significant difference is observed between the signatures generated under these two situations.
Paleozoic Seeds with Embryos

Seeds in a conifer cone from the Lower Permian of west Texas contain embryo tissue. These are the oldest plant embryos on record. Their development prior to seed dispersal shows that the sequence of embryo growth typical of most modern seed plants had evolved before the end of the Paleozoic Era.
Flexible informatics for linking experimental data to mathematical models via DataRail

Motivation: Linking experimental data to mathematical models in biology is impeded by the lack of suitable software to manage and transform data. Model calibration would be facilitated and models would increase in value were it possible to preserve links to training data along with a record of all normalization, scaling, and fusion routines used to assemble the training data from primary results. Results: We describe the implementation of DataRail, an open source MATLAB-based toolbox that stores experimental data in flexible multi-dimensional arrays, transforms arrays so as to maximize information content, and then constructs models using internal or external tools. Data integrity is maintained via a containment hierarchy for arrays, imposition of a metadata standard based on a newly proposed MIDAS format, assignment of semantically typed universal identifiers, and implementation of a procedure for storing the history of all transformations with the array. We illustrate the utility of DataRail by processing a newly collected set of ~22 000 measurements of protein activities obtained from cytokine-stimulated primary and transformed human liver cells. Availability:DataRail is distributed under the GNU General Public License and available at http://code.google.com/p/sbpipeline/ Contact: sbpipeline@hms.harvard.edu Supplementary information: Supplementary data are available at Bioinformatics online.
A generic system for form dropout

Recent advances in intelligent character recognition are enabling us to address many challenging problems in document image analysis. One of them is intelligent form analysis. This paper describes a generic system for form dropout when the filled-in characters or symbols are either touching or crossing the form frames. We propose a method to separate these characters from form frames whose locations are unknown. Since some of the character strokes are either touching or crossing the form frames, we need to address the following three issues: 1) localization of form frames; 2) separation of characters and form frames; and 3) reconstruction of broken strokes introduced during separation. The form frame is automatically located by finding long straight lines based on the block adjacency graph. Form frame separation and character reconstruction are implemented by means of this graph. The proposed system includes form structure learning and form dropout. First, a form structure-based template is automatically generated from a blank form which includes form frames, preprinted data areas and skew angle. With this form template, our system can then extract both handwritten and machine-typed filled-in data. Experimental results on three different types of forms show the performance of our system. Further, the proposed method is robust to noise and skew that is introduced during scanning.
WEST: Modern Technologies for Web People Search

In this paper we describe WEST (Web Entity Search Technologies) system that we have developed to improve people search over the Internet. Recently the problem of Web People Search (WePS) has attracted significant attention from both the industry and academia. In the classic formulation of WePS problem the user issues a query to a web search engine that consists of a name of a person of interest. For such a query, a traditional search engine such as Yahoo or Google would return webpages that are related to any people who happened to have the queried name. The goal of WePS, instead, is to output a set of clusters of webpages, one cluster per each distinct person, containing all of the webpages related to that person. The user then can locate the desired cluster and explore the webpages it contains.
Somite Development in Zebrafish

A full understanding of somite development requires knowledge of the molecular genetic pathways for cell determination as well as the cellular behaviors that underlie segmentation, somite epithelialization, and somite patterning. The zebrafish has long been recognized as an ideal organism for cellular and histological studies of somite patterning. In recent years, genetics has proven to be a very powerful complementary approach to these embryological studies, as genetic screens for zebrafish mutants defective in somitogenesis have identified over 50 genes that are necessary for normal somite development. Zebrafish is thus an ideal system in which to analyze the role of specific gene products in regulating the cell behaviors that underlie somite development. We review what is currently known about zebrafish somite development and compare it where appropriate to somite development in chick and mouse. We discuss the processes of segmentation and somite epithelialization, and then review the patterning of cell types within the somite. We show directly, for the first time, that muscle cell and sclerotome migrations occur at the same time. We end with a look at the many questions about somitogenesis that are still unanswered.
Television Watching and Risk of Obesity in American Adolescents

Abstract A large national database (U. S. Centers for Disease Control and Prevention [CDC], 2001) was analyzed for age, sex, race/ethnicity and television viewing among American adolescents aged 12-18 years. Body Mass Indices (BMI) were calculated from self-reported height and weight. Ninety-fifth percentile and above was classified as obese; <95th percentile was classified as non-obese. After controlling for age, sex and race, odds ratios were calculated for obesity and hours/day of television viewing on an average school day. Five or more hours of television viewing on an average school day roughly doubles the risk of obesity. This holds for both males and females. Moreover, these data show a linear trend toward obesity as daily television viewing increases. These data confirm — at the national level—the earlier regional studies linking television viewing to obesity. Health educators may now consider television viewing as a significant risk factor for adolescent obesity.
Artificial habitats and the restoration of degraded marine ecosystems and fisheries

Artificial habitats in marine ecosystems are employed on a limited basis to restore degraded natural habitats and fisheries, and more extensively for a broader variety of purposes including biological conservation and enhancement as well as social and economic development. Included in the aims of human-made habitats classified as artificial reefs are: Aquaculture/marine ranching; promotion of biodiversity; mitigation of environmental damage; enhancement of recreational scuba diving; eco-tourism development; expansion of recreational fishing; artisanal and commercial fisheries production; protection of benthic habitats against illegal trawling; and research. Structures often are fabricated according to anticipated physical influences or life history requirements of individual species. For example, many of the world’s largest reefs have been deployed as part of a national fisheries program in Japan, where large steel and concrete frameworks have been carefully designed to withstand strong ocean currents. In addition, the differing ecological needs of porgy and sea bass for shelter guided the design of the Box Reef in Korea as a device to enhance productivity of marine ranching. The effect of these and other structures on fisheries catch is positive. But caution must be exercised to avoid using reefs simply as fishing devices to heavily exploit species attracted to them. No worldwide database for artificial habitats exists. The challenge to any ecological restoration effort is to define the condition or possibly even the historic baseline to which the system will be restored; in other words, to answer the question: “Restoration to what?” Examples of aquatic ecosystem restoration from Hong Kong (fisheries), the Pacific Ocean (kelp beds), Chesapeake Bay (oysters) and the Atlantic Ocean (coral reefs) are discussed. The degree to which these four situations consider or can approach a baseline is indicated and compared (e.g., four plants per 100 m2 are proposed in one project). Measurement of performance is a key factor in restoration planning. These situations also are considered for the ecosystem and fishery contexts in which they are conducted. All use ecological data as a basis for physical design of restoration structures. The use of experimental, pilot and modeling practices is indicated. A context for the young field of marine restoration is provided by reviewing major factors in ecosystem degradation, such as high stress on 70% of commercially valuable fishes worldwide. Examples of habitat disruption include an extensive hypoxic/anoxic zone in the Gulf of Mexico and nutrient and contaminant burdens in the North Sea. Principles of ecological restoration are summarized, from planning through to evaluation. Alternate approaches to facilitate ecological recovery include land-use and ecosystem management and determining levels of human population, consumption and pollution.
Biomechanical analysis of gait adaptation in the nematode Caenorhabditis elegans

To navigate different environments, an animal must be able to adapt its locomotory gait to its physical surroundings. The nematode Caenorhabditis elegans, between swimming in water and crawling on surfaces, adapts its locomotory gait to surroundings that impose approximately 10,000-fold differences in mechanical resistance. Here we investigate this feat by studying the undulatory movements of C. elegans in Newtonian fluids spanning nearly five orders of magnitude in viscosity. In these fluids, the worm undulatory gait varies continuously with changes in external load: As load increases, both wavelength and frequency of undulation decrease. We also quantify the internal viscoelastic properties of the worm's body and their role in locomotory dynamics. We incorporate muscle activity, internal load, and external load into a biomechanical model of locomotion and show that (i) muscle power is nearly constant across changes in locomotory gait, and (ii) the onset of gait adaptation occurs as external load becomes comparable to internal load. During the swimming gait, which is evoked by small external loads, muscle power is primarily devoted to bending the worm's elastic body. During the crawling gait, evoked by large external loads, comparable muscle power is used to drive the external load and the elastic body. Our results suggest that C. elegans locomotory gait continuously adapts to external mechanical load in order to maintain propulsive thrust.
Parallel computation of a Krylov matrix for a sparse and structured input

As in our previous work, we reduce parallel computation of a Krylov matrix to solving a parametrized linear system of equations. This time we show that such a method is effective in the cases of banded matrices, sparse and structured matrices and triangular matrices.
The GLOBE Visualization Project: Using WWW in the Classroom

Though commercial interest in the World Wide Web is growing, the potential uses of the medium as a learning tool are numerous. The GLOBE Visualization Project is one such educational application. We have designed and implemented a WWW-based, user-friendly, language-independent, graphical user interface providing access to visualizations created for GLOBE, a multinational program of education and science. The target users of the system are K–12 students and their teachers from over 1100 schools in 39 countries; other clients include the GLOBE scientific investigators and members of the public internationally. Navigation is intuitive, and employs the metaphors of a “Control Panel” which changes the image appearing in a “Viewscreen.” The interface can be learned empirically by persons of all ages regardless of technical expertise or native language; context-sensitive help is provided for users who prefer documentation. The GLOBE Visualization server is on the World Wide Web at URL http://globe.gsfc.nasa.gov/globe/.
Revised chronology for late Pleistocene Mono Lake sediments based on paleointensity correlation to the global reference curve

Lakes are highly sensitive recorders of climate processes, but are extremely difficult to correlate precisely to ice-core and marine records, especially in the absence of reliable radiocarbon dates. Relative paleointensity (RPI) of Earth's magnetic field is an independent method of correlating high-resolution climate records, and can be applied to both marine and terrestrial sediments, as well as (inversely) correlated to the cosmogenic nuclide records preserved in ice cores. Here we present the correlation of an RPI record from Mono Lake, California to GLOPIS, the Global PaleoIntensity Stack, which increases the age estimation of the basal Mono Lake sediments by N20000 yr (20 kyr), from ∼40 ka (kyr before present) to 67 ka. The Mono Lake sediments thus preserve paleoclimatic records of most of the last glacial period, from 67 to 14 ka. In addition, the paleointensity-based age of 40 ka for the geomagnetic excursion preserved at Mono Lake indicates that this is a record of the global Laschamp excursion.
Modeling freezing injury in alfalfa to calculate forage yield. I. Model development and sensitivity analysis

Freezing injury can cause extensive yield loss in alfalfa (Medicago sativa L.) exposed to severe winters in cold climates. Existing simulation models for alfalfa either do not account for freezing injury effects or do not differentiate cultivars for their varying response to freezing stress and subsequent effects on crop productivity. The objective of this project was to incorporate cultivar-specific effects of freezing injury on forage dry matter (DM) yield into an existing alfalfa growth model to calculate annual forage yield during the life of an alfalfa crop. Numerical functions of cold tolerance, fall dormancy, and freezing injury were developed and integrated with the growth processes in the ALSIM 1 (Level 2) alfalfa modeL The new model, ALFACOLD, requires input of: daily solar irradiance, maximum and minimum air temperature, and precipitation; latitude; dates of harvest; cultivar's fall growth score (FGS); initial plant density; and maximum plant-available water in the root zone. The plant components modeled were leaf, stem, buds, and total nonstructural carbohydrates accumulated in the crown and root tissue. The model integrates the effects of soil moisture deficit, temperature, solar irradiance, and plant density on alfalfa growth, and the effects of subzero (°C) temperature on freezing injury and associated yield loss. Sensitivity of calculated forage DM yield to a ±25% change in selected model parameters was measured in cultivars of FGS 2, 3, and 4 during three production years of a 4-yr alfalfa crop. The model did not simulate growth during a seeding year. A cultivar's rate of cold hardening and lowest temperature tolerance during autumn and winter influenced forage yield more than did the rate of dehardening in the spring. Field validation of ALFACOLD calculations of forage yield is presented in a companion paper.
Climate change projections of sea level extremes along the California coast

California's coastal observations and global model projections indicate that California's open coast and estuaries will experience rising sea levels over the next century. During the last several decades, the upward historical trends, quantified from a small set of California tide gages, have been approximately 20 cm/century, quite similar to that estimated for global mean sea level. In the next several decades, warming produced by climate model simulations indicates that sea level rise (SLR) could substantially exceed the rate experienced during modern human development along the California coast and estuaries. A range of future SLR is estimated from a set of climate simulations governed by lower (B1), middle-upper (A2), and higher (A1fi) GHG emission scenarios. Projecting SLR from the ocean warming in GCMs, observational evidence of SLR, and separate calculations using a simple climate model yields a range of potential sea level increases, from 11 to 72 cm, by the 2070-2099 period. The combination of predicted astronomical tides with projected weather forcing, El Nino related variability, and secular SLR, gives a series of hourly sea level projections for 2005-2100. Gradual sea level rise progressively worsens the impacts of high tides, surge and waves resulting from storms, and also freshwater floods from Sierra and coastal mountain catchments. The occurrence of extreme sea levels is pronounced when these factors coincide. The frequency and magnitude of extreme events, relative to current levels, follows a sharply escalating pattern as the magnitude of future sea level rise increases.
Eddy stirring and phytoplankton patchiness in the subarctic North Atlantic in late summer

The spatial structure of phytoplankton distributions in the mesoscale eddy field of the North Atlantic (vicinity of 20iW, 59iN) was examined with a series of high resolution, towed transects. Data were obtained after the fall transition in August 1991 as part of the Marine Light-Mixed Layers (MLML) program. Measurements of chlorophyll fluorescence (CF) and the beam attenuation coeƒcient anomaly (Dc 490 ) show that chlorophyll and particles are confined to the surface mixed layer and seasonal pycnocline. Two water masses account for the potential temperature—salinity (h—S) structure in the region: North Atlantic Central Water from the sub-tropical gyre and Sub-Arctic Intermediate Water from the sub-polar gyre. These water masses carry distinct particle distributions based on measurements of CF and Dc 490 . Spatial distributions of CF and S in the mixed layer are spatially coherent for horizontal wavenumbers k less than a transition wavenumber k 5 +0.15 cycles km~1 (transition wavelength j 5 " k~1 +7 km). The horizontal distribution of h in the mixed layer is uncorrelated with S. Autospectra of h, S, CF, and Dc 490 vary approximately as k~2 for k less than k 5 . For k*k 5 ,C F and Dc 490 decrease approximately as k~3, while S spectra continue as k~2. These observations are consistent with physical control of phytoplankton distributions for k(k 5 by eddy advection. They are consistent with control by non-conservative biological processes for k*k 5 . This contradicts some theoretical models of chlorophyll spectra, which predict physical control of phytoplankton distributions above k 5 and biological control below. The contradiction may arise because the scales of variance sources assumed in the models are not consistent with observed scales in the MLML region. ( 1998 Elsevier Science Ltd. All rights reserved.
TrkB-like immunoreactivity is present on geniculocortical afferents in layer IV of kitten primary visual cortex.

Exogenous administration of the neurotrophins brain-derived neurotrophic factor (BDNF) or neurotrophin-4/5 (NT-4/5), or blockade of their endogenous actions, have been reported to affect the anatomic organization and physiological responses of neurons in developing mammalian primary visual cortex. Experimental alteration of levels of these neurotrophic factors can also influence the morphology of the geniculocortical afferents that project from the lateral geniculate nucleus (LGN) to primary visual cortex. BDNF and NT-4/5 are ligands of the TrkB tyrosine kinase receptor. Although multiple populations of cortical neurons express TrkB, it is not known whether geniculocortical afferents express this receptor on their axon branches in visual cortex. We have anatomically labeled geniculocortical afferents of postnatal day 40 kittens with the anterograde neuronal tracer Phaseolus vulgaris leucoagglutinin (PHA-L) and performed double-label immunofluorescence with a panel of anti-TrkB antibodies. Confocal microscopy and object-based colocalization analysis were used to measure levels of TrkB-like immunoreactivity (IR) on geniculocortical afferents in layer IV of primary visual cortex. By using a conservative analysis involving a comparison of measured colocalization with the amount of colocalization expected based on random overlap of TrkB puncta and PHA-L-labeled afferents, 3 of 5 anti-TrkB antibodies tested showed significant colocalization with the geniculocortical axons. Results for the other two antibodies were indeterminate. The indices obtained for colocalization of TrkB and geniculocortical afferents were also compared with the equivalent index obtained for GAD65, a protein that has a similar overall expression pattern to that of TrkB but is not expressed on geniculocortical axons. This analysis indicated that TrkB was present on geniculocortical axons for all five TrkB antibodies tested. TrkB-like IR was also observed on neuronal somata in the LGN. These results indicate that TrkB receptors on geniculocortical afferents are potential mediators of the actions of BDNF and NT-4/5 in developing visual cortex.
Pigou, Coase, common law, and environmental policy: Implications of the calculation debate

The implications of the calculation debate are explored for Pigouvian, Coasean, and common-law liability approaches to externality problems. There is no escaping Hayekian-Misean information problems, but the institutional setting within which environmental policies are resolved affects the domain of third-party calculation. The calculation required is likely to be significantly less under common-law arrangements than under administrative processes. The primary implication for environmental policy is that increased reliance on competitive market processes and the common law in copying with externality problems may be more effective than attempts to improve current administrative approaches.
Severe rhabdomyolysis associated with catha edulis(khat) use

Severe rhabdomyolysis is a rare complication of exposure to the recreational drug khat. Adverse reactions to khat thathave been reported in the literature include myocardial infarction and reversible vasoconstriction syndrome. Theactive ingredient, cathinone, is a naturally occurring beta-ketone amphetamine that may be responsible for this severecatecholaminergic response. Here we report a case of severe rhabdomyolysis following exposure to khat.
Detection of Narrow-Band Frequency Modulated Signal

The detection of a narrow-band frequency modulated signal in the presence of white Gaussian noise is investigated. Using NeymanPearson criteria, it has been shown that the receiver is similar to the matched filter and performance of the receiver is also identical to the binary detection of known Signals in the presence of white noise, it is assumed in the anlaysis that the signal to noise ratio is very small and that the amplitude of the sinusoidal modulating signal is also very small.
Notes on Generalized Lemniscates

A series of analytic and geometric features of generalized lemniscates are presented from an elementary and unifying point of view. A novel interplay between matrix theory and elementary geometry of planar algebraic curves is derived, with a variety of applicationvalue problem and Hardy space estimates to a root separation algorithm.
A simple method of reducing radiation exposure from myocardial perfusion imaging (MPI) exams. Voiding

2612 Objectives Patients and medical professionals are scrutinizing the need for diagnostic testing and how radiation exposure can be reduced. Technetium-99m tetrofosmin is one of the most common used tracers for perfusion in MPI studies. Published data states that 40% of tetrofosmin is excreted in the urine. Exposure time to the radiotracer is associated to the effects of radiation so by clearing the tracer from the body one may reduce these unwanted effects. The objective of this study was to evaluate the degree of techetium-99m (tetrofosmin) eliminated from the bladder in the first hours after injection as a simple method to reduce radiation exposure after an MPI study. Methods In the current workflow in a nuclear cardiology laboratory for the purposes of improving image quality, patients are sent to eat and drink after the stress test prior to imaging. For this study, hydration was encouraged so patients would be able to void when they returned for their stress image acquisition. Radiation was measured at one meter from the patient with an ion chamber prior to their stress images with a full bladder and again after emptying their bladder. Patients who could not void were excluded. Results Consecutive patients (n=98) measured an average of 10.6 mR/hr at one meter prior to voiding and 8.9 mR/hr a few minutes after voiding. This is a reduction of 16% in patients receiving an average of 41.6 mCi of Tc99m tetrofosmin (rest and stress) for their exam. Conclusions Reduced radiation exposure to patients and the general public is an ongoing concern. Encouraging patient hydration and voiding will effectively reduce the dose from an MPI study both to the patient and the community. This method is simple and applicable to all laboratories that perform MPIs around the world. Small and technical changes like the one proposed in this study may add up considerably and result in a substantial reduction in unnecessary radiation exposure.