CiteULike: Author Van

The One-Dimensional Network Society of Manuel Castells

Van — 2008-08-04T19:26:50-00:00

New Media Society, Vol. 1, No. 1. (1 April 1999), pp. 127-138.

10.1177/1461444899001001015

Configuring the Digital City of Amsterdam: Social Learning in Experimentation

Van — 2008-08-04T19:06:50-00:00

New Media Society, Vol. 3, No. 2. (1 June 2001), pp. 131-156.

Design and dispersion of new socio-technological configurations are studied by many varying sorts of scientific disciplines, ranging from communication studies to technology studies. In this article, the configuration and appropriation of new socio-technical constituencies are studied and subsequently interpreted in terms of a rather novel concept: social learning. On top of what is known about appropriation and configuration processes, social learning adds another point of view, elaborated from a perspective known as the social shaping of technology. It takes Beck and Giddens' reflexive modernization as starting point, and uses this to elaborate social learning into two dominant modes: the mode of experimentation and the mode of control. The Digital City of Amsterdam is used as exemplar to demonstrate configuration and appropriation processes and how these can be interpreted as elements of the mode of experimentation. 10.1177/14614440122226029

MASCOT: A Virtual Factory for Research and Development in Manufacturing Scheduling and Control

H Van — 2008-07-31T13:20:36-00:00

(1993)

Both researchers and industrial engineers interested in Manufacturing Scheduling and Control (MSC) are frustrated by the complexity of the problem and the wide range of approaches that have been proposed. The research environment often discourages scientists from the extensive effort and hands-on experience needed to gain a realistic view of the problem, and manufacturing engineers have no way to assess the relative practical value of the many proposed approaches. This white paper proposes a Manufacturing Scheduling and Control Testbed (MASCOT) to address these challenges to technology transfer: a Virtual (simulated) Factory, supporting a library of detailed industrial cases. Researchers can use MASCOT as a convenient source of realistic challenges, and vendors and manufacturers can use it to identify promising technologies for more rapid transfer to commercial application. In addition to this primary mission, the MASCOT Virtual Factory will provide several key technical elements in support of the broader vision of agile manufacturing enterprises. 1. Overview Manufacturing scheduling and control (MSC) is both a commercially important topic and an increasingly popular research domain in a number of academic fields, including industrial engineering, operations

Differences in hepatic cytochrome P450 activity correlate with the strain-specific biotransformation of medetomidine in AXJU and IIIVOJU inbred rabbits

H Avsaroglu — 2008-07-15T13:25:44-00:00

Journal of Veterinary Pharmacology & Therapeutics, Vol. 31, No. 4. (August 2008), pp. 368-377.

Hybrid Method for Personalized Search in Scientific Digital Libraries

Thanh-Trung Van — 2008-07-25T18:26:28-00:00

Computational Linguistics and Intelligent Text Processing (2008), pp. 512-521.

Users of information retrieval systems usually have to repeat the tedious process of searching, browsing, and refining queries until they find relevant documents. This is because different users have different information needs, but user queries are often short and, hence, ambiguous. In this paper we study personalized search in digital libraries using user profile. The search results could be re-ranked by taking into account specific information needs of different people. We study many methods for this purpose: citation-based method, content-based method and hybrid method. We conducted experiments to compare performances of these methods. Experimental results show that our approaches are promising and applicable in digital libraries.

The ligand for osteoprotegerin (OPGL) directly activates mature osteoclasts.

TL Burgess — 2008-07-24T00:01:53-00:00

The Journal of cell biology, Vol. 145, No. 3. (3 May 1999), pp. 527-538.

Osteoprotegerin (OPG) and OPG-ligand (OPGL) potently inhibit and stimulate, respectively, osteoclast differentiation (Simonet, W.S., D.L. Lacey, C.R. Dunstan, M. Kelley, M.-S. Chang, R. Luethy, H.Q. Nguyen, S. Wooden, L. Bennett, T. Boone, et al. 1997. Cell. 89:309-319; Lacey, D.L., E. Timms, H.-L. Tan, M.J. Kelley, C.R. Dunstan, T. Burgess, R. Elliott, A. Colombero, G. Elliott, S. Scully, et al. 1998. Cell. 93: 165-176), but their effects on mature osteoclasts are not well understood. Using primary cultures of rat osteoclasts on bone slices, we find that OPGL causes approximately sevenfold increase in total bone surface erosion. By scanning electron microscopy, OPGL-treated osteoclasts generate more clusters of lacunae on bone suggesting that multiple, spatially associated cycles of resorption have occurred. However, the size of individual resorption events are unchanged by OPGL treatment. Mechanistically, OPGL binds specifically to mature OCs and rapidly (within 30 min) induces actin ring formation; a marked cytoskeletal rearrangement that necessarily precedes bone resorption. Furthermore, we show that antibodies raised against the OPGL receptor, RANK, also induce actin ring formation. OPGL-treated mice exhibit increases in blood ionized Ca++ within 1 h after injections, consistent with immediate OC activation in vivo. Finally, we find that OPG blocks OPGL's effects on both actin ring formation and bone resorption. Together, these findings indicate that, in addition to their effects on OC precursors, OPGL and OPG have profound and direct effects on mature OCs and indicate that the OC receptor, RANK, mediates OPGL's effects.

The families of pathogenesis-related proteins, their activities, and comparative analysis of PR-1 type proteins

Van — 2008-05-19T16:30:19-00:00

Physiological and Molecular Plant Pathology, Vol. 55, No. 2. (August 1999), pp. 85-97.

The Haskell Road To Logic, Maths And Programming

Kees Doets — 2005-06-16T12:10:59-00:00

(31 May 2004)

UHE tau neutrino flux regeneration while skimming the Earth

Blanch Bigas — 2008-06-27T09:20:47-00:00

(12 Jun 2008)

The detection of Earth-skimming tau neutrinos has turned into a very promising strategy for the observation of ultra-high energy cosmic neutrinos. The sensitivity of this channel crucially depends on the parameters of the propagation of the tau neutrinos through the terrestrial crust, which governs the flux of emerging tau leptons that can be detected. One of the characteristics of this propagation is the possibility of regeneration through multiple $ν_τ ≤ftrightarrow τ$ conversions, which are often neglected in the standard picture. In this paper, we solve the transport equations governing the $ν_τ$ propagation and compare the flux of emerging tau leptons obtained allowing regeneration or not. We discuss the validity of the approximation of neglecting the $ν_τ$ regeneration using different scenarios for the neutrino-nucleon cross-sections and the tau energy losses.

Observation of a neutrino burst from the supernova SN1987A

K Hirata — 2008-06-27T09:15:01-00:00

Physical Review Letters, Vol. 58, No. 14. (6 April 1987), 1490.

Rational drug design via intrinsically disordered protein.

Y Cheng — 2008-01-04T12:46:31-00:00

Trends Biotechnol, Vol. 24, No. 10. (October 2006), pp. 435-442.

Despite substantial increases in research funding by the pharmaceutical industry, drug discovery rates seem to have reached a plateau or perhaps are even declining, suggesting the need for new strategies. Protein-protein interactions have long been thought to provide interesting drug discovery targets, but the development of small molecules that modulate such interactions has so far achieved a low success rate. In contrast to this historic trend, a few recent successes raise hopes for routinely identifying druggable protein-protein interactions. In this Opinion article, we point out the importance of coupled binding and folding for protein-protein signalling interactions generally, and from this and associated observations, we develop a new strategy for identifying protein-protein interactions that would be particularly promising targets for modulation by small molecules. This novel strategy, based on intrinsically disordered protein, has the potential to increase significantly the discovery rate for new molecule entities.

Mesh refinement for particle-in-cell plasma simulations: Applications to and benefits for heavy ion fusion

JL Vay — 2008-06-03T15:24:58-00:00

Laser and Particle Beams, Vol. 20, No. 04. (2003), pp. 569-575.

The numerical simulation of the driving beams in a heavy ion fusion power plant is a challenging task, and simulation of the power plant as a whole, or even of the driver, is not yet possible. Despite the rapid progress in computer power, past and anticipated, one must consider the use of the most advanced numerical techniques, if we are to reach our goal expeditiously. One of the difficulties of these simulations resides in the disparity of scales, in time and in space, which must be resolved. When these disparities are in distinctive zones of the simulation region, a method which has proven to be effective in other areas (e.g., fluid dynamics simulations) is the mesh refinement technique. We discuss the challenges posed by the implementation of this technique into plasma simulations (due to the presence of particles and electromagnetic waves). We present the prospects for and projected benefits of its application to heavy ion fusion, in particular to the simulation of the ion source and the final beam propagation in the chamber. A collaboration project is under way at Lawrence Berkeley National Laboratory between the Applied Numerical Algorithms Group (ANAG) and the Heavy Ion Fusion group to couple the adaptive mesh refinement library CHOMBO developed by the ANAG group to the particle-in-cell accelerator code WARP developed by the Heavy Ion Fusion–Virtual National Laboratory. We describe our progress and present our initial findings.

Models for the Brain

Van — 2008-05-28T02:31:39-00:00

Nature, Vol. 225, No. 5228. (10 January 1970), pp. 177-178.

Response profiles to texture border patterns in area V1

Hans-Christoph Nothdurft — 2008-05-21T21:25:26-00:00

Visual Neuroscience, Vol. 17, No. 03. (2000), pp. 421-436.

4. Empiricism and Scientific Methodology

Fraassen — 2007-12-13T20:28:56-00:00

The Scientific Image, pp. 70-97.

2. Arguments Concerning Scientific Realism

Fraassen — 2007-12-13T20:28:56-00:00

The Scientific Image, pp. 6-41.

Modelling Applicability of Fractal Analysis to Efficiency of Soil Exploration by Roots

TC Walk — 2008-05-15T11:18:10-00:00

Annals of Botany (July 2004), pp. 119-128.

• Background and Aims Fractal analysis allows calculation of fractal dimension, fractal abundance and lacunarity. Fractal analysis of plant roots has revealed correlations of fractal dimension with age, topology or genotypic variation, while fractal abundance has been associated with root length. Lacunarity is associated with heterogeneity of distribution, and has yet to be utilized in analysis of roots. In this study, fractal analysis was applied to the study of root architecture and acquisition of diffusion-limited nutrients. The hypothesis that soil depletion and root competition are more closely correlated with a combination of fractal parameters than by any one alone was tested.• Model The geometric simulation model SimRoot was used to dynamically model roots of various architectures growing for up to 16 d in three soil types with contrasting nutrient mobility. Fractal parameters were calculated for whole roots, projections of roots and vertical slices of roots taken at 0, 2·5 and 5 cm from the root origin. Nutrient depletion volumes, competition volumes, and relative competition were regressed against fractal parameters and root length.• Key Results Root length was correlated with depletion volume, competition volume and relative competition at all times. In analysis of three-dimensional, projected roots and 0 cm slices, log(fractal abundance) was highly correlated with log(depletion volume) when times were pooled. Other than this, multiple regression yielded better correlations than regression with single fractal parameters. Correlations decreased with age of roots and distance of vertical slices from the root origin. Field data were also examined to see if fractal dimension, fractal abundance and lacunarity can be used to distinguish common bean genotypes in field situations. There were significant differences in fractal dimension and fractal abundance, but not in lacunarity.• Conclusions These results suggest that applying fractal analysis to research of soil exploration by root systems should include fractal abundance, and possibly lacunarity, along with fractal dimension.

The Peierls transition in low-dimensional electronic crystals

Smaalen — 2004-12-06T22:42:11-00:00

Acta Crystallographica Section A: Foundations of Crystallography, Vol. 61, No. 1. (01 January 2005), pp. 51-61.

Linking Gene Expression to Function: Metabolic Flexibility in the Normal and Diseased Heart

Heinrich Taegtmeyer — 2008-05-10T10:47:35-00:00

Ann NY Acad Sci, Vol. 1015, No. 1. (1 May 2004), pp. 202-213.

Metabolism transfers energy from substrates to ATP. As a "metabolic omnivore," the normal heart adapts to changes in the environment by switching from one substrate to another. We propose that this flexibility is lost in the maladapted, diseased heart. Both adaptation and maladaptation are the results of metabolic signals that regulate transcription of key cardiac regulatory genes. We propose that metabolic remodeling precedes, initiates, and sustains functional and structural remodeling. The process of metabolic remodeling then becomes a target for pharmacological intervention restoring metabolic flexibility and normal contractile function of the heart. 10.1196/annals.1302.017

Incidence, risk factors and consequences of falls among elderly subjects living in the community: A criteria-based analysis

Paul Stalenhoef — 2008-05-08T19:16:49-00:00

Eur J Public Health, Vol. 7, No. 3. (1 September 1997), pp. 328-334.

In order to obtain an overview of the incidences, risk factors and health consequences of falls among elderly persons living in the community from the available literature, a Medline computer search of publications over the period 1981-1994 was carried out. Fourteen studies met the following inclusion criteria: i) the study is an original investigation of falls among the elderly, ii) the study deals with the incidence, risk factors and/or consequences of falls among the elderly and iii) the study refers to a population at risk consisting of persons aged 60 years or over belonging to a population relevant to general practice. The selected studies were subjected to a methodological assessment on the basis of 10 methodological criteria. All the studies were independently assessed by 1 author and 1 assistant to obtain a methodological consensus. The relevant outcomes of these studies are reported. Pooling of data was not performed because of relevant differences between the studies. Two studies met all methodological criteria and 2 other studies were second best. These 4 studies were given preference. Approximately 30% of subjects older than 65 years fall at least once a year and approximately 15% fall recurrently. The main risk factors for falls among the elderly belong to the intrinsic (patient-related) risk factors: cognitive impairment, balance and gait disorders, use of sedatives and hypnotics, a history of stroke, advanced age, arthritis of the knee and a high level of dependence. Extrinsic (environment-related) risk factors did not play a significant role in any of the studies. Not all studies dealt with the health consequences of falls among the elderly. Major injuries were reported in 0.5-9% and fractures in 3-14%. 10.1093/eurpub/7.3.328

Supplementary health insurance as a tool for risk-selection in mandatory basic health insurance markets

Francesco Paolucci — 2008-04-28T13:58:55-00:00

Health Economics, Policy and Law, Vol. 2, No. 02. (2007), pp. 173-192.

As the share of supplementary health insurance (SI) in health care finance is likely to grow, SI may become an increasingly attractive tool for risk-selection in basic health insurance (BI). In this paper, we develop a conceptual framework to assess the probability that insurers will use SI for favourable risk-selection in BI. We apply our framework to five countries in which risk-selection via SI is feasible: Belgium, Germany, Israel, the Netherlands, and Switzerland. For each country, we review the available evidence of SI being used as selection device. We find that the probability that SI is and will be used for risk-selection substantially varies across countries. Finally, we discuss several strategies for policy makers to reduce the chance that SI will be used for risk-selection in BI markets.

Range expansion due to urbanization: Increased food resources attract Grey-headed Flying-foxes (Pteropus poliocephalus) to Melbourne

Nicholas Williams — 2006-03-02T07:34:55-00:00

Austral Ecology, Vol. 31, No. 2. (April 2006), pp. 190-198.

Self-structuring in spatial evolutionary ecology

Lion — 2008-02-02T00:12:29-00:00

Ecology Letters, Vol. 11, No. 3. (March 2008), pp. 277-295.

Spermatogonial stem cells: characteristics and experimental possibilities

Pedro Aponte — 2006-02-18T12:23:40-00:00

Apmis, Vol. 113, No. 11-12. (November 2005), pp. 727-742.

Increased expression of lysosomal acid phosphatase in CLN3-defective cells and mouse brain tissue

Pohl — 2007-11-28T02:31:03-00:00

Journal of Neurochemistry, Vol. 103, No. 6. (December 2007), pp. 2177-2188.

Photonic logic NORgate based on two symmetric microring resonators

TA Ibrahim — 2008-02-22T02:53:54-00:00

Opt. Lett., Vol. 29, No. 23. (1 December 2004), pp. 2779-2781.

We demonstrate an all-optical NOR logic gate based on symmetric GaAs–AlGaAs microring resonators whose resonances are closely matched. Two input pump data streams are tuned close to one resonance of the symmetric microrings to switch a probe beam tuned to another resonance by two-photon absorption. The switching energy of the gate is 20 pJ/pulse, and the switching window is 40 ps, limited by the carrier lifetime. The use of two rings provides for better cascading in photonic logic circuits because of the higher number of available ports.

Interpretation of ANOVA models for microarray data using PCA

De Haan — 2007-01-26T03:04:41-00:00

Bioinformatics, Vol. 23, No. 2. (15 January 2007), pp. 184-190.

The Economics of Child Labor

Kaushik Basu — 2008-02-20T08:52:56-00:00

The American Economic Review, Vol. 88, No. 3. (1998), pp. 412-427.

If child labor as a mass phenomenon occurs not because of parental selfishness but because of the parents' concern for the household's survival, the popular argument for banning child labor loses much of its force. However, this assumption about parental decision-making coupled with the assumption of substitutability in production between child and adult labor could result in multiple equilibria in the labor market, with one equilibrium where children work and another where adult wage is high and children do not work. The paper establishes this result and discusses its policy implications.

Game controller text entry with alphabetic and multi-tap selection keyboards

Thomas Költringer — 2008-02-17T10:07:25-00:00

(2007), pp. 2513-2518.

In this paper we present a longitudinal study comparing an alphabetical selection keyboard to a multi-tap selection keyboard using a game controller as input device. Our experiment showed the alphabetic selection keyboard to be faster for novice (7.72 wpm vs. 6.34 wpm) and expert users (11.87 wpm vs. 9.64 wpm). The multi-tap selection keyboard was more error prone than the alphabetic selection keyboard. Qualitative results showed that over time the alphabetic selection keyboard was preferred by the users.

The squirrel as a rodent model of the human visual system

Van — 2008-02-05T18:41:18-00:00

Visual Neuroscience, Vol. 23, No. 05. (2006), pp. 765-778.

Fully resolved simulations of colliding monodisperse spheres in forced isotropic turbulence

Andreas Cate — 2008-01-18T11:48:18-00:00

Journal of Fluid Mechanics, Vol. 519, No. -1. (2004), pp. 233-271.

Promotion of human adipocyte precursor replication by 17beta-estradiol in culture.

DA Roncari — 2008-01-08T21:53:11-00:00

J Clin Invest, Vol. 62, No. 3. (September 1978), pp. 503-508.

The influence of 17beta-estradiol and 17alpha-estradiol on adult human omental adipocyte precursors grown in a propagating culture system was studied. Cells were grown in subculture in the presence or absence of hormone. 17beta-estradiol resulted in significant promotion of adipocyte precursor replication, as determined by cell counting and incorporation of radioactive thymidine into DNA. The hormone stimulated cell multiplication in the concentration range 0.5--500 ng/ml growth medium. The highest level tested was 500 ng/ml. The maximal effects were obtained at 50 ng/ml (P less than 0.001 by paired t test, 48 h after hormone addition). All 10 cell strains (five were derived from men and five from women) that were tested responded similarly to the hormone. 17beta-estradiol did not affect cell size. 17alpha-estradiol did not promote the replication of adipocyte precursors, nor did it influence cell size. Thus, 17beta-estradiol, which is the active isomer in known target tissues, stimulates the multiplication of human adipocyte precursors in culture.

Economics and public health: engaged to be happily married!

Brouwer — 2007-03-31T18:13:50-00:00

European Journal of Public Health, Vol. 17, No. 2. (1 April 2007), pp. 122-123.

The impact of animated interface agents: a review of empirical research

Doris Dehn — 2005-01-29T22:49:42-00:00

International Journal of Human-Computer Studies, Vol. 52, No. 1. (January 2000), pp. 1-22.

Over the last years, the animation of interface agents has been the target of increasing interest. Largely, this increase in attention is fuelled by speculated effects on human motivation and cognition. However, empirical investigations on the effect of animated agents are still small in number and differ with regard to the measured effects. Our aim is two-fold. First, we provide a comprehensive and systematic overview of the empirical studies conducted so far in order to investigate effects of animated agents on the user's experience, behaviour and performance. Second, by discussing both implications and limitations of the existing studies, we identify some general requirements and suggestions for future studies.

Succession of aquatic vegetation driven by reduced water-level fluctuations in floodplain lakes

G Van — 2005-04-17T10:41:18-00:00

Journal of Applied Ecology, Vol. 42, No. 2. (April 2005), pp. 251-260.

Ecological stability, evolutionary stability and the ESS maximum principle

TL Vincent — 2007-10-26T18:34:00-00:00

Evolutionary Ecology, Vol. 10, No. 6. (1 November 1996), pp. 567-591.

Summary Since the fitness of each individual organism in a biological community may be affected by the strategies of all other individuals in the community, the essential element of a ‘game’ exists. This game is an evolutionary game where the individual organisms (players) inherit their strategies from continuous play of the game through time. Here, the strategies are assumed to be constants associated with certain adaptive parameters (such as sunlight conversion efficiency for plants or body length in animals) in a set of differential equations which describe the population dynamics of the community. By means of natural selection, these parameters will evolve to a set of strategy values that natural selection, by itself, can no longer modify, i.e. an evolutionarily stable strategy (ESS). For a given class of models, it is possible to predict the outcome of this evolutionary process by determining ESSs using an ESS maximum principle. However, heretofore, the proof of this principle has been based on a limited set of conditions. Herein, we generalize the proof by removing certain restrictions and use instead the concept of an ecological stable equilibrium (ESE). Individuals in a biological community will be at an ESE if fixing the strategies used by the individuals results in stable population densities subject to perturbations in those densities. We present both necessary and sufficient conditions for an ESE to exist and then use the ESE concept to provide a very simple proof of the ESS maximum principle (which is a necessary condition for an ESS). A simple example is used to illustrate the difference between a strategy that maximizes fitness and one that satisfies the ESS maximum principle. In general they are different. We also look for ESEs in Lotka—Volterra competition and use the maximum principle to determine when an ESE will be an ESS. Finally, we examine the applicability of these ideas to matrix games.

Changes in contact and support exchange in personal networks after widowhood

Maurice Guiaux — 2007-09-12T01:12:36-00:00

Personal Relationships, Vol. 14, No. 3. (2007), pp. 457-473.

Abstract The convoy model conceptualizes older adults networks of personal relationships as convoys of social support. This prospective study examined how contact and support in several relationships changed due to widowhood. Using observations between 1992 and 2002 from the Longitudinal Aging Study Amsterdam, multilevel models describe change in contact and support of 227 widowed and 408 married older adults. Contact and support were low before widowhood and increased in all relationships after widowhood, and more so in child and sibling relationships. Around 2.5 years after widowhood, contact and support started to decrease. Our findings increase our understanding of the heterogeneity of network changes in old age and of the instability of the network as a social convoy in late life.

Genetic diversity in diploid vs. tetraploid Rorippa amphibia (Brassicaceae)

Pieternella Luttikhuizen — 2007-08-29T13:10:45-00:00

Molecular Ecology, Vol. 0, No. 0. (0000), pp. ???-???.

Abstract The frequency of polyploidy increases with latitude in the Northern Hemisphere, especially in deglaciated, recently colonized areas. The cause or causes of this pattern are largely unknown, but a greater genetic diversity of individual polyploid plants due to a doubled genome and/or a hybrid origin is seen as a likely factor underlying selective advantages related to life in extreme climates and/or colonization ability. A history of colonization in itself, as well as a recent origin, and possibly a limited number of polyploidization events would all predict less genetic diversity in polyploids than in diploids. The null hypothesis of higher gene diversity in polyploids has to date hardly been quantified and is here tested in self-incompatible Rorippa amphibia (Brassicaceae). The species occurs in diploid and tetraploid forms and displays clear geographical polyploidy in Europe. On the basis of eight microsatellite loci it can be concluded that the level of gene diversity is higher in tetraploids than in diploids, to an extent that is expected under neutral evolution when taking into account the larger effective population size in the doubled cytotype. There is thus no evidence for reduced genetic diversity in the tetraploids. The evidence presented here may mean that the tetraploids origin is not recent, has not been affected by bottlenecks and/or that tetraploids were formed multiple times while an effect of introgression may also play a role.

A new 2-D systolic digital filter architecture without global broadcast

Lan-Da Van — 2007-08-07T08:44:11-00:00

IEEE Trans. Very Large Scale Integr. Syst., Vol. 10, No. 4. (August 2002), pp. 477-486.

In this paper, we propose two-dimensional (2-D) systolic-array infinite-impulse response (IIR) and finite-impulse response (FIR) digital filter architectures without global broadcast, by the hybrid of a modified reordering scheme and a new systolic transformation. This architecture has local broadcast, lower-quantization error, and zero latency without sacrificing the number of multipliers, as well as delay elements under the satisfactory critical period. Furthermore, we extend this new architecture to a useful 2-D systolic cascade-form architecture and provide the comprehensive error analysis for the proposed architectures.

Pelagic ecology of a northern boundary current system: effects of upwelling on the production and distribution of sardine (Sardinops sagax), anchovy (Engraulis australis) and southern bluefin tuna (Thunnus maccoyii) in the Great Australian Bight

Tim Ward — 2006-03-31T13:58:18-00:00

Fisheries Oceanography, Vol. 15, No. 3. (May 2006), pp. 191-207.

micro-checker: software for identifying and correcting genotyping errors in microsatellite data

Van — 2007-07-17T13:13:40-00:00

Molecular Ecology Notes, Vol. 4, No. 3. (2004), pp. 535-538.

Abstract DNA degradation, low DNA concentrations and primer-site mutations may result in the incorrect assignment of microsatellite genotypes, potentially biasing population genetic analyses. micro-checker is windowsR-based software that tests the genotyping of microsatellites from diploid populations. The program aids identification of genotyping errors due to nonamplified alleles (null alleles), short allele dominance (large allele dropout) and the scoring of stutter peaks, and also detects typographic errors. micro-checker estimates the frequency of null alleles and, importantly, can adjust the allele and genotype frequencies of the amplified alleles, permitting their use in further population genetic analysis. micro-checker can be freely downloaded from http://www.microchecker.hull.ac.uk/ .

Unilateral storage of fear memories by the amygdala.

HT Blair — 2007-07-12T21:45:18-00:00

J Neurosci, Vol. 25, No. 16. (20 April 2005), pp. 4198-4205.

Pavlovian fear conditioning is an associative learning task in which subjects are trained to respond defensively to a neutral conditioned stimulus (CS) by pairing it with an aversive unconditioned stimulus (US). This type of learning depends critically on the amygdala, and evidence suggests that synaptic plasticity within the lateral nucleus of the amygdala (LA) may be responsible for storing memories of the CS-US association. In the present study, we trained rats to fear an auditory CS by pairing it with a shock US delivered to one eyelid. Conditioning was assessed by measuring freezing responses evoked by the CS during a subsequent test session. The amygdala was unilaterally inactivated during either the training or the testing session by intracranial infusions of muscimol into the LA. We found that both acquisition and expression of conditioned freezing to the CS depended on the amygdala contralateral but not ipsilateral from the eyelid where the shock US was delivered. To explain this surprising result, we propose that the shock US is relayed from the eyelid to the amygdala via lateralized nociceptive sensory pathways, which causes memories of the CS-US association to be stored by the amygdala contralateral but not ipsilateral from the shocked eyelid. Our results demonstrate that the fear-learning circuitry of the amygdala is functionally lateralized according to the anatomical source of predicted threats. In future studies, the cellular mechanisms of emotional memory storage might be pinpointed by identifying cellular processes that occur only in the amygdala contralateral but not ipsilateral from the US during lateralized fear conditioning.

ULTRASONOGRAPHIC ASSESSMENT OF FRACTURE HEALING AFTER PLATE OSTEOSYNTHESIS

M Risselada — 2007-07-04T00:28:16-00:00

Veterinary Radiology & Ultrasound, Vol. 48, No. 4. (2007), pp. 368-372.

The goals of this study were to assess the ability of ultrasonography (US) to assess uncomplicated fracture healing and to establish normal images. Twenty-two dogs, ranging in age from 6 to 180 months were studied. Body weight ranged from 2.2 to 60 kg. All fractures were treated by plate osteosynthesis. US (B-mode and power Doppler) and radiography were performed until both were consistent with complete healing. B-mode US was performed in all dogs, and power Doppler US in 14. Fracture healing was judged to be complete based on US earlier than when based on radiography. The tissue immediately adjacent to the plate appeared vascularized on power Doppler images at a time when the tissue at the fracture site had a negative power Doppler exam. US appears useful for assessment of primary fracture healing and power Doppler was useful for detecting vascularization at the fracture site in nonhealed fractures. Power Doppler interrogation should be performed away from any metal implant, as a result from an interrogation adjacent to an implant will not reflect actual vascularization at the fracture site.

ULTRASOUND APPROACH TO THE CANINE DISTAL TIBIA AND TROCHLEAR RIDGES OF THE TALUS

Tiziana Liuti — 2007-07-04T00:27:43-00:00

Veterinary Radiology & Ultrasound, Vol. 48, No. 4. (2007), pp. 361-367.

The aim of the present study was to evaluate to what extent the distal tibia and the trochlear ridges of the talus can be examined with ultrasound (US) in the dog and to establish a protocol for an optimal US examination of these ridges. Six hind limbs of deceased adult mixed-breed dogs were used. In two limbs, needles were placed using US guidance on the trochlea of the talus, just dorsal to and plantar to the distal tibia: one with the tarsal joint in extension and one with the joint in flexion. Then mediolateral (ML) radiographs of both joints were made with the needle in place to determine the percentage of the trochlear ridge of the talus that can be seen using US imaging. An US examination of the tarsal joint was performed on the four other limbs using microconvex (8 MHz) and linear (12 MHz) transducers (Logiq 7) and compound imaging. A three-step protocol was performed including a dorsal approach with the limb extended and the linear transducer (step I), a plantar approach with the limb flexed and the linear transducer (step II), and a plantar approach with the limb flexed and the microconvex transducer (step III). After the US examination, the four limbs were frozen and sectioned, two in a transverse and two in a sagittal plane. Bony structures on the US images were matched with the corresponding anatomic sections. The distal tibia and both trochlear ridges of the talus were easily recognized on the US images using the proposed protocol. When combining the dorsal and plantar approaches, it was possible to visualize up to 75% of the trochlear ridges of the talus in the dog.

LC-MS in Metabonomics: Optimization of Experimental Conditions for the Analysis of Metabolites in Human Urine

Timothy Waybright — 2006-09-12T00:22:57-00:00

Journal of Liquid Chromatography & Related Technologies, Vol. 29, No. 17. (2006), pp. 2475-2497.

VASCULAR ANOMALY CAUSING SUBCLAVIAN STEAL AND CERVICAL MYELOPATHY IN A DOG: DIAGNOSIS AND ENDOVASCULAR MANAGEMENT

H Westwort — 2006-04-22T15:11:24-00:00

Veterinary Radiology & Ultrasound, Vol. 47, No. 3. (June 2006), pp. 265-269.

Genetic isolation of fragmented populations is exacerbated by drift and selection

Y Willi — 2007-02-19T11:06:50-00:00

Journal of Evolutionary Biology, Vol. 20, No. 2. (2007), pp. 534-542.

Abstract Reduced genetic variation at marker loci in small populations has been well documented, whereas the relationship between quantitative genetic variation and population size has attracted little empirical investigation. Here we demonstrate that both neutral and quantitative genetic variation are reduced in small populations of a fragmented plant metapopulation, and that both drift and selective change are enhanced in small populations. Measures of neutral genetic differentiation (FST) and quantitative genetic differentiation (QST) in two traits were higher among small demes, and QST between small populations exceeded that expected from drift alone. This suggests that fragmented populations experience both enhanced genetic drift and divergent selection on phenotypic traits, and that drift affects variation in both neutral markers and quantitative traits. These results highlight the need to integrate natural selection into conservation genetic theory, and suggests that small populations may represent reservoirs of genetic variation adaptive within a wide range of environments.

What is the relationship between changes in canopy leaf area and changes in photosynthetic CO2 flux in arctic ecosystems?

LE Street — 2007-02-06T18:20:57-00:00

Journal of Ecology, Vol. 95, No. 1. (2007), pp. 139-150.

Summary 1 The arctic environment is highly heterogeneous in terms of plant distribution and productivity. If we are to make regional scale predictions of carbon exchange it is necessary to find robust relationships that can simplify this variability. One such potential relationship is that of leaf area to photosynthetic CO2 flux at the canopy scale. 2 In this paper we assess the effectiveness of canopy leaf area in explaining variation in gross primary productivity (GPP): (i) across different vegetation types; (ii) at various stages of leaf development; and (iii) under enhanced nutrient availability. To do this we measure net CO2 flux light response curves with a 1 x 1 m chamber, and calculate GPP at a photosynthetic photon flux density (PPFD) of 600 umol m-2 s-1. 3 At a subarctic site in Sweden, we report 10-fold variation in GPP among natural vegetation types with leaf area index (LAI) values of 0.05-2.31 m2 m-2. At a site of similar latitude in Alaska we document substantially elevated rates of GPP in fertilized vegetation. 4 We can explain 80% of the observed variation in GPP in natural vegetation (including vegetation measured before deciduous leaf bud burst) by leaf area alone, when leaf area is predicted from measurements of normalized difference vegetation index (NDVI). 5 In fertilized vegetation the relative increase in leaf area between control and fertilized treatments exceeds the relative increase in GPP. This suggests that higher leaf area causes increased self-shading, or that lower leaf nitrogen per unit leaf area causes a reduction in the rate of photosynthesis. 6 The results of this study indicate that canopy leaf area is an excellent predictor of GPP in diverse low arctic tundra, across a wide range of plant functional types. Journal of Ecology (2007) 95, 139-150 doi: 10.1111/j.1365-2745.2006.01187.x

Enhancement of Farmland Biodiversity within Set-Aside Land

Josh Van Buskirk — 2006-12-12T16:34:22-00:00

Conservation Biology, Vol. 18, No. 4. (2004), pp. 987-994.

The efficacy of agricultural set-aside policies for protecting farmland biodiversity is widely debated. Based on a meta-analysis of 127 published studies, we found that land withdrawn from conventional production unequivocally enhances biodiversity in North America and Europe. The number of species of birds, insects, spiders, and plants is 1-1.5 standard deviation units higher on set-aside land, and population densities increase by 0.5-1 standard deviation units. Set-aside land may be especially beneficial for desirable taxa because North American bird species that have exhibited population declines react most positively to set-aside agricultural land. Larger and older plots protect more species and higher densities, and set-aside land is more effective in countries with less-intensive agricultural practices and higher fractions of land removed from production. Although policies specifically designed to protect biodiversity might work even better, current incentives clearly improve the standing of plants and animals in farmland. Mejora de la Biodiversidad en Tierras Cultivadas dentro de Terrenos de Reserva Resumen: La eficiencia de las politicas de reservas agricolas para la proteccion de la biodiversidad en tierras cultivadas esta ampliamente debatida. Con base en un meta-analisis de 127 estudios publicados, encontramos que terrenos retirados de la produccion convencional inequivocamente mejoran la biodiversidad en Norte America y Europa. El numero de especies de aves, insectos, aranas y plantas es 1-1.5 unidades de desviacion estandar mas alto en terrenos de reserva, y las densidades de poblacion incrementan en 0.5-1 unidades de desviacion estandar. Los terrenos de reserva pueden ser especialmente beneficos para taxones deseables porque especies de aves norteamericanas que han presentado una declinacion poblacional reaccionan positivamente a terrenos agricolas de reserva. Parcelas mas grandes y viejas protegen a mas especies y tienen mayores densidades, y los terrenos de reserva son mas efectivos en paises con practicas agricolas menos intensivas y con mayores fracciones de tierras removidas de la produccion. Aunque las politicas disenadas especificamente para proteger la biodiversidad pueden ser mejores aun, los incentivos actuales claramente mejoran la situacion de plantas y animales en tierras agricolas.

Transferability of Species Distribution Models: a Functional Habitat Approach for Two Regionally Threatened Butterflies

Wouter Vanreusel — 2006-12-04T13:57:57-00:00

Conservation Biology, Vol. 0, No. 0. (0000), pp. ???-???.

Numerous models for predicting species distribution have been developed for conservation purposes. Most of them make use of environmental data (e.g., climate, topography, land use) at a coarse grid resolution (often kilometres). Such approaches are useful for conservation policy issues including reserve-network selection. The efficiency of predictive models for species distribution is usually tested on the area for which they were developed. Although highly interesting from the point of view of conservation efficiency, transferability of such models to independent areas is still under debate. We tested the transferability of habitat-based predictive distribution models for two regionally threatened butterflies, the green hairstreak (Callophrys rubi) and the grayling (Hipparchia semele), within and among three nature reserves in northeastern Belgium. We built predictive models based on spatially detailed maps of area-wide distribution and density of ecological resources. We used resources directly related to ecological functions (host plants, nectar sources, shelter, microclimate) rather than environmental surrogate variables. We obtained models that performed well with few resource variables. All models were transferable-although to different degrees-among the independent areas within the same broad geographical region. We argue that habitat models based on essential functional resources could transfer better in space than models that use indirect environmental variables. Because functional variables can easily be interpreted and even be directly affected by terrain managers, these models can be useful tools to guide species-adapted reserve management. Transferibilidad de Modelos de Distribucion de Especies: un Enfoque de Habitat Funcional para Dos mariposas regionalmente Amenazadas Resumen: Se han desarrollado numerosos modelos para predecir la distribucion de especies con fines de conservacion. La mayoria de ellos hacen uso de datos ambientales (e.g., clima, topografia, uso de suelo) a una resolucion gruesa (a menudo kilometros). Tales enfoques son utiles para el tema de politicas de conservacion incluyendo la seleccion de redes de reservas. La eficiencia de los modelos predictivos de la distribucion de especies generalmente es probada en la zona para la que fueron desarrollados. Aunque muy interesante desde el punto de vista de la eficiencia de la conservacion, la transferibilidad de dichos modelos a areas independientes aun esta en debate. Probamos la transferibilidad de modelos predictivos de distribucion basados en el habitat para dos mariposas regionalmente amenazadas, Callophrys rubi e Hipparchia semele dentro y entre tres reservas naturales en el noreste de Belgica. Construimos modelos predictivos con base en mapas espacialmente detallados de la distribucion y densidad de los recursos ecologicos. Utilizamos recursos directamente relacionados con las funciones ecologicas (plantas hospederas, fuentes de nectar, refugios y microclima) en lugar de variables ambientales sustitutas. Obtuvimos modelos que funcionaron bien con pocas variables de recursos. Todos los modelos fueron transferibles-aunque en diferentes grados-entre las areas independientes dentro de la misma region geografica general. Argumentamos que los modelos de habitat basados en recursos funcionales esenciales se transfieren mejor que los modelos que utilizan variables ambientales indirectas. Debido a que las variables ambientales pueden ser facilmente interpretadas, y pueden ser directamente afectadas por gestores de recursos, estos modelos pueden ser herramientas utiles para guiar la gestion de reservas para especies determinadas.