bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolving neural models of path integration
Authors: Vickerstaff R. J. , Di Paolo E. A.
Published: August 2005

We use a genetic algorithm to evolve neural models of path integration,with particular emphasis on reproducing the homing behaviour of Cataglyphis fortis ants. This is done within the context of a complete model system, including an explicit representation of the animal's movements within its environment. We show that it is possible to produce a neural network without imposing a priori any particular system for the internal representation of the animal's home vector. The best evolved network obtained is analysed in detail and is found to resemble the bicomponent model of Mittelstaedt. Because of the presence of leaky integration, the model can reproduce the systematic navigation errors found in desert ants. The model also naturally mimics the searching behaviour that ants perform once they have reached their estimate of the nest location. The results support possible roles for leaky integration and cosine-shaped compass response functions in path integration.
Hypoxia progressively lowers thermal gaping thresholds in bearded dragons,Pogona vitticeps
Authors: Tattersall Glenn J. , Gerlach Rebecca M.
Published: August 2005

Most animals, including reptiles, lower body temperature(Tb) under hypoxic conditions. Numerous physiological and behavioural traits significant to the regulation of Tb are altered by hypoxia in ways that suggest an orchestrated adjustment of Tb at a new and lower regulated level. We examined this matter in bearded dragons, Pogona vitticeps, a species of reptile that naturally exhibits open mouth gaping at high temperatures, presumably in order to promote evaporation and thus prevent or avoid further increases in Tb. The threshold for the onset of gaping (assessed as the temperature at which lizards spent 50% of their time gaping) was reduced from 36.9°C in normoxia to 35.5°C at 10% and 34.3°C at 6%O2. The overall magnitude or degree of gaping, measured qualitatively, was more pronounced at lower temperatures in hypoxia. Females consistently had lower gaping threshold temperatures than did males, and this difference was retained throughout exposure to hypoxia. In addition to gaping,evaporative water loss from the cloaca may also play a significant role in temperature regulation, since the ambient temperature at which cloacal discharge occurred was also reduced significantly in hypoxia. The results reported herein strongly support the view that hypoxia reduces temperature set-point in lizards and that such changes are coordinated by specific behavioural thermoeffectors that modulate evaporative water loss and thus facilitate a high potential for controlling or modifying Tb.
Study of the Advanced Application Characteristics of a Solar Solid Adsorption Refrigerator
Authors: Li M. , Wang R.Z.
Published: August 2005

On the basis of previous research work on solar solid adsorption refrigeration, some advanced application methods for a solar ice maker have been studied. These include the efficient design of a new adsorbent bed; experimental studies of working pairs for a solar ice maker using activated carbon—methanol and activated carbon—ethanol; the effects of sky cloud cover on a solar ice maker; and the efficient utilization of a solar ice maker with provision for heating and cooling. The provision of tables to assist in the choice of a mass-produced solar ice maker was also examined. Simulation of the characteristics of a solar ice maker has been undertaken in some areas in Tibet where the natural climatic conditions appear to be ideal for the operation of such a device.
Adsorption of Nitrate Ions onto Sepiolite and Surfactant-Modified Sepiolite
Authors: Özcan Adnan , Şahin Mutlu , Özcan Asiye Safa
Published: August 2005

The adsorption of nitrate ions onto clay minerals has not been given much attention, possibly because clay surfaces are negatively charged. In order to increase the positive charge on the surface, sepiolite was modified in the present studies by treatment with dodecylethyldimethylammonium (DEDMA) bromide. After such modification, it was found that the maximum amount of nitrate ion adsorbed occurred at a pH value of 2.0.

The chemical composition of natural sepiolite was determined by EDX methods and surface characterization of both natural and modified sepiolite samples was undertaken using FT-IR spectroscopic techniques. The adsorption of nitrate ions onto these adsorbents was determined by ion chromatography. The kinetic parameters of the adsorption process were calculated and it was shown that the reaction kinetic data could be fitted using the pseudo-second-order rate model. The calculated results indicate that both natural and surfactant-modified sepiolite are effective sorbents for the removal of anionic contaminants; however, the surfactant-modified sepiolite (453 mmol/kg) was more effective than the unmodified sepiolite (408 mmol/kg) in this respect. The adsorption data obtained were well described by the Freundlich adsorption isotherm.
Adsorption of Quadrupolar, Diatomic Nitrogen onto Graphitized Thermal Carbon Black and in Slit-Shaped Carbon Pores. Effects of Surface Mediation
Authors: Do D.D. , Do H.D.
Published: August 2005

In this paper, we study the effect of solid surface mediation on the intermolecular potential energy of nitrogen, and its impact on the adsorption of nitrogen on a graphitized carbon black surface and in carbon slit-shaped pores. This effect arises from the lower effective interaction potential energy between two particles close to the surface compared to the potential energy of the same two particles when they are far away from the surface.

A simple equation is proposed to calculate the reduction factor and this is used in the Grand Canonical Monte Carlo (GCMC) simulation of nitrogen adsorption on graphitized thermal carbon black. With this modification, the GCMC simulation results agree extremely well with the experimental data over a wide range of pressure; the simulation results with the original potential energy (i.e. no surface mediation) give rise to a shoulder in the neighbourhood of monolayer coverage and a significant over-prediction of the second and higher layer coverages.

The influence of this surface mediation on the dependence of the pore-filling pressure on the pore width is also studied. It is shown that such surface mediation has a significant effect on the pore-filling pressure. This implies that the use of the local isotherms obtained from the potential model without surface mediation could give rise to a serious error in the determination of the pore-size distribution.
Noise Prediction for Increasingly Complex Jets. Part I: Methods and Tests
Authors: Shur Michael L. , Spalart Philippe R. , Strelets Michael Kh.
Published: August 2005

This Part I presents a detailed description of a numerical system built and tested with the final goal of reaching an accuracy of 2–3 dB over a meaningful range of frequencies for airliner engine noise, while having low empiricism and a general-geometry capability. The turbulence is treated by Large-Eddy Simulation with grids of around 1 million points, slightly upwind-biased high-order differencing, and implicit time integration. The code can incorporate boundaries and multi-block grids (thus avoiding the centerline singularity), and capture shocks. The sub-grid scale model is de-activated, because on present grids it strongly interferes with transition in the mixing layer. Without unsteady inflow forcing, the shear-layer roll-up and three-dimensionalization are realistic and reasonably insensitive to the grid. The far-field noise is computed using the permeable Ffowcs-Williams/Hawkings (FWH) formulation without external quadrupoles. The treatment of the disk that closes the FWH surface near the outflow must be approximate, since the turbulent region is unbounded, and is crucial; it benefits from a change of variable from density to pressure, and other mitigating steps. Tests are presented in support of the key elements of the strategy. In a simple isothermal jet, the system is close to the 2–3 dB target both in terms of directivity and of spectrum, up to a Strouhal number of about 1.5. In Part II, the following effects are explored with overall success: jet Mach numbers from 0.3 to slightly supersonic with under-expansion (generating shock cells), jet heating, co-flow, and “synthetic chevrons.”
Numerical Investigation of High Speed Free Shear Flow Instability and Mach Wave Radiation
Authors: Kudryavtsev Alexey N. , Khotyanovsky Dmitry V.
Published: August 2005

The linear stability theory is used to investigate the emergence, in supersonic free shear flows such as mixing layers and fully expanded plane jets, of supersonically travelling instability waves, which do not vanish in the ambient space. It is shown that, at supersonic convective Mach numbers, the slow and fast supersonic modes in the mixing layer as well as the sinuous supersonic mode in the plane jet should lead to Mach wave radiation. Direct numerical simulations are further used to study nonlinear stages of instability development in high-speed mixing layers and jets. They have shown that the formation of oblique shock waves attached to large-scale structures is observed in free shear flows forced by modes with supersonic phase speeds. The relevance of this phenomenon to the noise generation by high-speed jets is discussed.
Structure of Acoustic Radiation from an Artificially Excited Supersonic Boundary Layer
Authors: Semionov Nickolay V. , Kosinov Alexander D.
Published: August 2005

An experimental study of the controlled disturbance field, introduced into the free stream with the help of the local source of disturbances, was carried out. The controlled disturbances were excited in the supersonic boundary layer by using a local disturbance generator designed based on the amount of discharge in the chamber in the plate. This process was accompanied by radiation of controlled disturbances into the free stream. This radiation from the system “discharge-boundary layer” was used as controlled disturbances in the free stream. The acoustic nature of the radiation was obtained. The levels, wave characteristics and modes of the artificial fluctuations have been obtained by hot-wire measurements in the free stream of the supersonic wind tunnel at a Mach number of 2.
Influence of Thermodynamic Nonequilibrium on the Acoustic Properties of Gases
Authors: Molevich Nonna E. , Klimov Anatoly I. , Makaryan Vladimir G.
Published: August 2005

This paper is a brief review of results of experimental and theoretical studies in the field of acoustics of nonequilibrium gas-plasma media. New acoustical properties of nonequilibrium media caused by the change in sign of the second viscosity and the dispersion coefficients are considered. Such media are acoustically active. Conditions are discussed for generating new nonlinear acoustical structures.
On the Prediction of Turbulent Jet Noise Using Traditional Aeroacoustic Methods
Authors: Khritov K.M. , Kozlov V.Ye. , Krasheninnikov S.Yu. , Lebedev A.B. , Lyubimov D.A. , Maslov V.P. , Mironov A.K. , Reent K.S. , Secundov A.N. , Yakubovsky K.Ya. , Birch Stanley F.
Published: August 2005

Several experimental, computational and theoretical results devoted to turbulence jet noise are described. All these results were obtained at CIAM in collaboration with the Boeing Company. The selected topics are combined and described from a single point of view. In spite of the many publications in the classical literature devoted to jet noise, many jet noise problems are not completely solved, and most current jet noise prediction methods are still highly empirical and rely heavily on an existing experimental data base. At the same time, many of the available experimental results are not fully reliable and some are even contradictory. The goal of this paper is, therefore, to explore and discuss some of the possibilities and limitations of classical aeroacoustics methods.
Mixer-Ejector Nozzles: Acoustic and Thrust Characteristics
Authors: Krasheninnikov Sergey Ju. , Mironov Alexey K. , Pavlyukov Evgeny V. , Shenkin Andrey V. , Zhitenev Vladimir K.
Published: August 2005

The paper presents the review of the CIAM/TsAGI investigations of mixer-ejector models, which could be considered to be prototypes of real variable area nozzles for future supersonic aircraft. Acoustic and aerodynamic characteristics of both 2-D and axisymmetrical models were obtained. The influence of nozzle geometry (number of lobes, lobe shape, ejector length, auxiliary inlets in the ejector walls) on its noise and thrust performances is discussed.

The experimental data show that the best mixer-ejector configuration tested provides a noise reduction efficiency of about 3 ∼ 3.5 PNdB per 1% thrust loss at static conditions.
Incentives for Efficient Inventory Management: The Role of Historical Cost
Authors: Baldenius Tim , Reichelstein Stefan
Published: August 2005

This paper examines inventory management from an incentive perspective. We show that when a manager has private information about future attainable revenues, the residual income performance measure based on historical cost can achieve optimal (second-best) incentives with regard to managerial effort as well as production and sales decisions. The LIFO (last-in–first-out) inventory flow rule is shown to be preferable to the FIFO (first-in–first-out) rule for the purpose of aligning incentives. Our analysis also finds support for the lower-of-cost-or-market inventory-valuation rule in situations where the manager receives new information after the initial contracting stage.
What Actually Happened to the Inventories of American Companies Between 1981 and 2000?
Authors: Chen Hong , Frank Murray Z. , Wu Owen Q.
Published: August 2005

This paper examines the inventories of publicly traded American manufacturing companies between 1981 and 2000. The median of inventory holding periods were reduced from 96 days to 81 days. The average rate of inventory reduction is about 2% per year. The greatest reduction was found for work-in-process inventory, which declined by about 6% per year. Finished-goods inventories did not decline. Firms with abnormally high inventories have abnormally poor long-term stock returns. Firms with slightly lower than average inventories have good stock returns, but firms with the lowest inventories have only ordinary returns.
Personalized Pricing and Quality Differentiation
Authors: Choudhary Vidyanand , Ghose Anindya , Mukhopadhyay Tridas , Rajan Uday
Published: August 2005

We develop an analytical framework to investigate the competitive implications of personalized pricing (PP), whereby firms charge different prices to different consumers based on their willingness to pay. We embed PP in a model of vertical product differentiation and show how it affects firms’ choices over quality. We show that firms’ optimal pricing strategies with PP may be nonmonotonic in consumer valuations. When the PP firm has high quality, both firms raise their qualities relative to the uniform pricing case. Conversely, when the PP firm has low quality, both firms lower their qualities. Although many firms are trying to implement such pricing policies, we find that a higher-quality firm can actually be worse off with PP. While it is optimal for the firm adopting PP to increase product differentiation, the non-PP firm seeks to reduce differentiation by moving in closer in the quality space. While PP results in a wider market coverage, it also leads to aggravated price competition between firms. Because this entails a change in equilibrium qualities, the nature of the cost function determines whether firms gain or lose by implementing such PP policies. Despite the threat of first-degree price discrimination, we find that PP with competing firms can lead to an overall increase in consumer welfare.
Efficient Production-Distribution System Design
Authors: Elhedhli Samir , Goffin Jean-Louis
Published: August 2005

The production-distribution system design is an integral part of the general supply chain design. This paper proposes a novel solution methodology for this problem that is based on Lagrangean relaxation, interior-point methods, and branch and bound. Unlike classical approaches, Lagrangean relaxation is applied in a two-level hierarchy, branch and bound is based on a Lagrangean lower bound and column generation (branch and price), while interior-point methods are used within a cutting-plane context (analytic centre cutting-plane method—ACCPM). Numerical results demonstrate that the two-level approach outperforms the classical approach and provides a very sharp lower bound that is the (proven) optimal in most cases.
Assessing the Resource Base of Japanese and U.S. Auto Producers: A Stochastic Frontier Production Function Approach
Authors: Lieberman Marvin B. , Dhawan Rajeev
Published: August 2005

The “resource-based view of the firm” has become an important conceptual framework in strategic management but has been widely criticized for lack of an empirical base. To address this deficit, we utilize a new method for identifying interfirm differences in efficiency within the context of stochastic frontier production functions. Using data on Japanese and U.S. automobile manufacturers, we develop measures of resources and capabilities and test for linkages with firm performance. The results show the influence of manufacturing proficiency and scale economies at the firm and plant level. We apply the parameter estimates to account for Toyota’s superior efficiency relative to other producers.
Ratiometric Singlet Oxygen Nano‐optodes and Their Use for Monitoring Photodynamic Therapy Nanoplatforms
Authors: Cao Youfu , Koo Yong‐Eun Lee , Koo Sang Man , Kopelman Raoul
Published: August 2005

Ratiometric photonic explorers for bioanalysis with biologically localized embedding (PEBBLE) nanoprobes have been developed for singlet oxygen, using organically modified silicate (ORMOSIL) nanoparticles as the matrix. A crucial aspect of these ratiometric singlet‐oxygen fluorescent probes is their minute size. The ORMOSIL nanoparticles are prepared via a sol‐gel–based process and the average diameter of the resultant particles is about 160 nm. These sensors incorporate the singlet‐oxygen–sensitive 9,10‐dimethyl anthracene as an indicator dye and a singlet‐oxygen–insensitive dye, octaethylporphine, as a reference dye for ratiometric fluorescence‐based analysis. We have found experimentally that these nanoprobes have much better sensitivity than does the conventional singlet‐oxygen–free dye probe, anthracene‐9, 10‐dipropionic acid disodium salt. The much longer lifetime of singlet oxygen in the ORMOSIL matrix, compared to aqueous solutions, in addition to the relatively high singlet oxygen solubility because of the highly permeable structure and the hydrophobic nature of the outer shell of the ORMOSIL nanoparticles, results in an excellent overall response to singlet oxygen. These nanoprobes have been used to monitor the singlet oxygen produced by “dynamic nanoplatforms” that were developed for photodynamic therapy. The singlet oxygen nanoprobes could potentially be used to quantify the singlet oxygen produced by macrophages.
Photoconvertible Fluorescent Protein EosFP: Biophysical Properties and Cell Biology Applications
Authors: Nienhaus G. Ulrich , Nienhaus Karin , Hölzle Angela , Ivanchenko Sergey , Renzi Fabiana , Oswald Franz , Wolff Michael , Schmitt Florian , Röcker Carlheinz , Vallone Beatrice , Weidemann Wolfgang , Heilker Ralf , Nar Herbert , Wiedenmann Jörg
Published: August 2005

EosFP is a fluorescent protein from the coral Lobophyllia hemprichii that changes its fluorescence emission from green to red upon irradiation with near‐UV light. Here we present the spectroscopic properties of wild‐type EosFP and a variety of monomeric and dimeric mutants and provide a structural interpretation of its oligomerization and photoconversion, which is based on X‐ray structure analysis of the green and red species that we reported recently. Because functional expression of the monomeric EosFP variant is limited to temperatures of 30°C, we have developed a tandem dimer. This construct, in which two EosFP subunits are connected by a flexible 12 amino acid linker, expresses well after fusion with the androgen and endothelin A receptors at 37°C. A variety of applications in cellular imaging, developmental biology and automated high‐content screening applications are presented, which demonstrate that EosFP is a powerful tool for in vivo monitoring of cellular processes.
Efficacy of Formalin and Hydrogen Peroxide to Increase Survival of Channel Catfish Infected with Saprolegniasis
Authors: Rach Jeff J , Schreier Theresa , Gaikowski Mark P , Schleis Susan M
Published: August 2005

The efficacy of formalin and hydrogen peroxide to increase survival associated with external saprolegniasis on fingerlings of channel catfish Ictalurus punctatus was evaluated in four laboratory trials. Fungal epizootics were initiated according to procedures developed in a fungal-disease model. Fish were abraded with a dremel tool and then placed in an aerated static infection tank containing fungal-infected hemp seeds held in teaballs that were suspended in 100 L of water for 24 h (trials 1–3) or 6 h (trial 4). In the formalin trials, treatment regimens of 0, 82, and 166 mg/L (trial 1) or 0 and 83 mg/L (trial 2) were administered to channel catfish for 60 min once every other day for a total of three treatments (trial 1) or once daily for a total of seven treatments (trial 2). In the hydrogen peroxide trials, treatment regimens of 0, 75, and 102 mg/L (trial 3) or 0 and 75 mg/L (trial 4) were administered to channel catfish for 60 min once every other day for a total of three treatments. Each treatment regimen was tested in triplicate, with 10 fish per replicate. Formalin exposures of 83 (seven treatments; 33% survival) and 166 mg/L (three treatments; 63% survival) for 60 min significantly (P ≤ 0.01) increased channel catfish survival in comparison with controls (of which 3% and 13%, respectively, survived). In trial 4, hydrogen peroxide exposure of 75 mg/L (63% survival) for 60 min significantly (P ≤ 0.01) increased channel catfish survival in comparison with the untreated controls (13% survival). Formalin and hydrogen peroxide treatments were effective in increasing survival in channel catfish infected with fungus.
Culture Studies of the Devils River Minnow
Authors: Gibson J R , Fries J N
Published: August 2005

Requirements for indoor culture of the threatened Devils River minnow Dionda diaboli were developed and refined. Spawning over gravel previously occurred in experimental systems with a riffle area under a compressed seasonal cycle (temperature and photoperiod). Subsequently, spawning occurred without the riffle area and seasonal cycle. Given only gravel (15- 25 mm) and rock (40–80 mm) as spawning substrate, more eggs were found in the gravel (Mann-Whitney tests, P < 0.001). Additionally, pairwise breeding was achieved in both wild-stock and first-generation fish; average survival from egg to fry was improved from about 25% to 45%; a growth curve was developed, in which fish averaging 7 mm total length (TL) grew to an average of 35 mm TL in 192 d; growth rate was noted to decline as culture density increased (nonlinear regression, P < 0.001). Sexually dimorphic characteristics (yellow fins, blue body coloration, and nuptial tuberculation) and aspects of spawning behavior (substrate necessity, territoriality, and mating) are discussed.
Efficacy of Common Disinfectants against Mycobacterium marinum
Authors: Mainous Mary E. , Smith Stephen A.
Published: August 2005

Mycobacteriosis is an important bacterial disease of freshwater, brackish-water, and marine fishes. In addition to affecting many species of wild and cultured fish, the aquatic mycobacterial species present a potentially important zoonotic risk to humans. Reduction or elimination of the causative pathogen from an aquarium or aquaculture facility is therefore paramount. This study examined a variety of commercially available disinfectants for their efficacy in reducing or eliminating Mycobacterium marinum. In this study, ethyl alcohol (50% and 70%), benzyl-4-chlorophenol/phenylphenol (1%), and sodium chlorite (mixed as 1:5:1 or 1:18:1 [base : water : activator]) were the most effective disinfectants evaluated; each reduced or eliminated the number of detectable M. marinum within 1 min of contact time. Sodium hypochlorite (50,000 mg/L) was moderately effective but required a minimum contact time of 10 min to reduce bacterial counts. Ethyl alcohol (30%), N-alkyl dimethyl benzyl ammonium chloride (1:256; two formulations), and potassium peroxymonosulfate– sodium chloride (1%) did not substantially reduce bacterial counts even after 60 min of contact time.
Process‐Based Modeling of Timothy Regrowth
Authors: van Oijen Marcel , Höglind Mats , Hanslin Hans Martin , Caldwell Nick
Published: August 2005

Previously, the literature on the growth of timothy (Phleum pratense L.) in Scandinavia was reviewed and a simple process‐based model was developed to explain and predict the response of this species to different environments and management regimes. The model could not be tested in detail, because only biomass data were available at the time. However, recent experimental work has generated a large (n = 633) and uniquely detailed dataset on the growth and underlying physiology of timothy and its response to cutting at different growth stages. The present study aimed to use this dataset to test the model, and to use the model to identify the key physiological and morphological mechanisms that determine the regrowth rate of timothy after cutting. Model testing consisted of comparing simulations and measurements for eight variables: biomass, leaf area index (LAI), tiller and leaf density, rates of leaf appearance and elongation, carbohydrate concentration, and specific leaf area. Although the new data referred to a different cultivar, a different site, and different years from those used in the original model parameterization, the model was still able to account for nearly half the variation in the dataset [r2 = 0.468, normalized root mean squared error (RMSE) = 0.631]. This suggested that the key assumptions of the model (i.e., dependence of growth and allocation on the source‐sink balance of the plants and a close link between tillering and leaf area dynamics) were plausible. However, the original model was not able to account for the observation that cutting at early heading tended to be followed by a longer lag phase than cutting at anthesis. We identified six mechanisms, not previously incorporated in the model, that improved its behavior: (1, 2) dependence of tillering and leaf appearance rate on carbohydrate concentration, (3, 4) dependence of leaf appearance and leaf elongation rate on plant phenological stage, (5) sprouting of new tillers from decapitated generative tillers, and (6) proportionality of the number of elongating leaves with tiller size. Incorporation of these mechanisms, followed by reparameterization using a Metropolis‐Hastings Monte Carlo method, improved performance statistics (r2 = 0.521, normalized RMSE = 0.415) and explained the long duration of slow growth after early cutting. These mechanisms may thus be keys to understanding timothy regrowth.
Planting Date Effects on Winter Triticale Dry Matter and Nitrogen Accumulation
Authors: Schwarte Aaron J. , Gibson Lance R. , Karlen Douglas L. , Liebman Matt , Jannink Jean‐Luc
Published: August 2005

Addition of triticale (×Triticosecale Wittmack) into more diversified cropping systems could provide valuable economic and environmental benefits to producers in the U.S. Corn and Soybean Belt. To maximize triticale value, research was conducted to identify planting dates that allowed maximum dry matter production and N capture. Winter triticale was planted at 10‐d intervals from 15 September to 15 October at three Iowa locations: central, northeast, and southwest for two growing seasons: 2002–2003 and 2003–2004. Aboveground dry matter production, N concentration, and N removal were greater at southwest Iowa than central and northeast Iowa. Dry matter production decreased as planting was delayed from late September to late October. Nitrogen accumulation at any time during the spring and summer was greater for September‐ than October‐planted triticale in 2002–2003. At the end of the 2002–2003 season, mid‐September‐planted triticale had accumulated 37% more N than mid‐October‐planted triticale. In 2003–2004, total N capture occurring by early May was less for late‐October‐planted triticale than the other three planting dates, but there were no differences in N capture among the four planting dates from late May until maturity. Dry matter production was greatest when at least 300 growing degree days (GDDs) (base 4°C) accumulated between planting and 31 December. These results suggest that triticale should be planted in September to maximize spring forage yield and N accumulation although later planting dates would provide a higher quality forage if harvest was not delayed into late spring and summer.
Simulated Aspen Understory Microclimate Effects on Alfalfa Growth
Authors: Powell George W. , Bork Edward W.
Published: August 2005

Understory plant growth in agroforestry systems is strongly influenced both positively and negatively by the microclimate created by the overstory. Growth chambers were used to isolate and compare the effects of photosynthetically active radiation (PAR) and humidity (and resultant leaf/atmosphere vapor pressure differences) on the early growth and development of alfalfa (Medicago sativa L.). Leaf temperature corresponded closely to air temperature and did not vary between humidity treatments. Predictably, PAR had a strong effect on alfalfa growth with significant effects on the size and mass of all yield components, as well as relative growth rates. Humidity effects were less pronounced, although still significantly increased total alfalfa leaf area (24–30%), stem mass (17–42%), shoot mass (13–33%), and height (23–24%). Increased leaf area was attributed to 21 to 25% greater leaf numbers rather than area per leaf. Unlike the effects of PAR, elevated humidity did not increase the stem mass/length ratio, indicating the increased stem mass was due primarily to stem lengthening, and not thickening or increased tissue density. In general, humidity had small, positive effects on alfalfa growth, but was strongly expressed only within variables positively affected by PAR. This is consistent with the theory that the primary benefit of humidity is through enhanced photosynthetic gas exchange. Results suggest elevated humidity under aspen (Populus tremuloides Michx.) appears to compensate for some lost growth potential in the understory, but cannot fully counteract the reduced photosynthetic potential of alfalfa at the two PAR levels tested.
Interactions of Nitrogen, Weather, Soil, and Irrigation on Corn Yield
Authors: Derby Nathan E. , Steele Dean D. , Terpstra Jeff , Knighton Raymond E. , Casey Francis X. M.
Published: August 2005

Numerous factors that affect corn yield in the Northern Great Plains are not considered in current N fertilizer recommendations. A linear model to describe the interactions of N fertility, weather, soil, and irrigation on corn (Zea mays L.) yield was developed for a 6‐yr field study in southeastern North Dakota. Varying rates of postemergence fertilizer N were applied to plots in four quadrants of a sprinkler‐irrigated field. Four irrigation‐scheduling methods varied by year (Y) and quadrant (Q). Grain yield, stover yield, and N uptake response to a covariate (soil N plus starter fertilizer N), N treatment (Nt), Q, Y, irrigation treatment (I), previous irrigation treatment (P), and the two‐way interactions that included Nt, were investigated using standard regression techniques. Yield increased significantly with Nt up to a rate of 135 kg N ha−1 for most Y, Q, and I. Average yearly yield was adversely affected by cool climatic conditions in 2 yr. Soil conditions in two quadrants resulted in a 1.25 Mg ha−1 average annual yield reduction compared with the other quadrants. An irrigation scheduling method utilizing a water balance algorithm resulted in higher yields compared with the other scheduling methods. The interactions of Nt with Q, Y, and I were significant. Optimized total N rates (the sum of soil nitrate N, starter N, and postemergence Nt) derived from quadratic‐linear plateau analysis varied (232–374 kg N ha−1) with Y, Q, and I and averaged 295 kg N ha−1. Soil properties, soil moisture availability, and yearly climatic factors should be considered when making fertilizer recommendations.
Forage Yield and Species Composition in Years following Kura Clover Sod‐Seeding into Grass Swards
Authors: Laberge Guillaume , Seguin Philippe , Peterson Paul R. , Sheaffer Craig C. , Ehlke Nancy J.
Published: August 2005

Sod‐seeding legumes into grass pastures improves forage productivity and quality, but legumes currently used lack persistence. Field experiments were established in Québec and Minnesota to compare postseeding year performance of two cultivars (‘Cossack’ and ‘Endura’) of Kura clover (Trifolium ambiguum M. Bieb.) against that of red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) sod‐seeded using different intensities of herbicide sod suppression [paraquat (0.9 kg a.i. ha−1) and glyphosate (0.8 or 3.3 kg a.i. ha−1)] with or without seeding year N fertilization (110 kg N ha−1). Red clover had the greatest yield and contribution to total forage yield in the first postseeding year [avg. 2.7 Mg dry matter (DM) ha−1, 50% clover], white clover (WC) was intermediate (avg. 1.5 Mg DM ha−1, 32% clover), and Kura clover (KC) ranked last (avg. 1.2 DM Mg ha−1, 27% clover). Yields of KC were, however, similar to WC in three of five sites. Clover yields and content in the first postseeding year were positively associated with intensity of sod suppression. Kura clover content increased over time; at the first harvest of the second postseeding year, it had greater clover yield and content (avg. 750 kg DM ha−1, 45% clover) than red clover (avg. 160 kg DM ha−1, 25% clover) and WC (avg. 60 kg DM ha−1, 11% clover). Seeding year N fertilization, which enhanced seeding year yields, had inconsistent effects on postseeding year yield and botanical composition but rarely had negative effects on clover. Kura clover can be established in permanent pastures via sod‐seeding.
Sexual dimorphism of cusp dimensions in human maxillary molars
Authors: Kondo Shintaro , Townsend Grant C. , Yamada Hiroyuki
Published: August 2005

Cusp dimensions of human maxillary molars were compared between males and females to determine whether the later‐developed, distal cusps displayed greater sexual dimorphism than the earlier‐developed, mesial cusps, and whether the later‐forming second molar displayed greater sexual dimorphism than the first molar. First and second permanent molar crowns (M1 and M2) were measured indirectly, using dental casts obtained from 117 Japanese (65 males and 52 females). Measurements included maximum mesiodistal and buccolingual crown diameters and the diameters of the four main cusps: the paracone, protocone, metacone, and hypocone. Mean values of crown dimensions were larger in males than in females for both M1 and M2, but the sexual difference in protocone diameter of M1 was not significant. The protocone in M1 showed the least amount of sexual dimorphism, followed by the metacone, hypocone, and paracone, while in M2, the percentage sexual dimorphism corresponded to the order of cusp formation: paracone, protocone, metacone, and hypocone. With the exception of the paracone diameter, M2 showed greater sexual dimorphism than M1. Sexual dimorphism was not always greater in the later‐developed, distal cusps of M1 or M2, but the protocone, the most important cusp in terms of occlusal function, displayed the least dimorphism in M1. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Morphometric analysis of lumbar vertebrae in extinct Malagasy strepsirrhines
Authors: Shapiro Liza J. , Seiffert Cornelia V.M. , Godfrey Laurie R. , Jungers William L. , Simons Elywn L. , Randria Gisèle F.N.
Published: August 2005

Previous research on subfossil lemurs has revealed much about the positional behavior of these extinct strepsirrhines, but a thorough quantitative analysis of their vertebral form and function has not been performed. In this study, 156 lumbar vertebrae of Pachylemur, Archaeolemur, Megaladapis, Mesopropithecus, Babakotia, and Palaeopropithecus (11 species in all) were compared to those of 26 species of extant strepsirrhines and haplorhines. Lumbar shape was compared among species, using a principal components analysis (PCA) in conjunction with selected vertebral indices. The first principal component revealed strong separation between Palaeopropithecus at one extreme, and Archaeolemur/Pachylemur at the other, with Babakotia, Mesopropithecus, and Megaladapis in an intermediate position. Palaeopropithecus has markedly shorter spinous processes and wider laminae than do the other subfossil taxa, consistent with sloth‐like, inverted suspensory postures. The moderately reduced lumbar spinous processes of Babakotia, Mesopropithecus, and Megaladapis are convergent with those of lorisids and Pongo, reflecting antipronogrady, but a less specialized adaptation than that of Palaeopropithecus. Archaeolemur and Pachylemur share relatively elongated spinous processes, in conjunction with other features (e.g., transverse process orientation and relatively short vertebral bodies) indicative of pronograde, quadrupedal locomotion characterized by reduced agility. All subfossil taxa exhibit adaptations emphasizing lumbar spinal stability (e.g., relatively short vertebral bodies, and transverse processes that are not oriented ventrally); we believe this probably reflects convergent mechanical demands connected to large body size, irrespective of specific locomotor mode. Reconstructions of positional behavior in subfossil lemurs based on lumbar vertebrae are largely consistent with those based on other aspects of the postcrania. Am J Phys Anthropol, 2005. © 2005 Wiley‐Liss, Inc.
Derivatization chemistries for determination of serotonin, norepinephrine and dopamine in brain microdialysis samples by liquid chromatography with fluorescence detection
Authors: Yoshitake T. , Kehr J. , Todoroki K. , Nohta H. , Yamaguchi M.
Published: August 2005

The present paper provides an overview on currently developed derivatization chemistries and techniques for determination of monoamine neurotransmitters serotonin (5‐HT), norepinephrine (NE) and dopamine (DA) in microdialysis samples by microbore liquid chromatography with fluorescence detection. In mild alkaline conditions, 5‐hydroxyindoles and catecholamines react with benzylamine (BA), forming highly fluorescent 2‐phenyl‐4,5‐pyrrolobenzoxazoles and 2‐phenyl(4,5‐dihydropyrrolo) [2,3‐f]benzoxazoles, respectively. However, for derivatization of DA a higher fluorescence intensity was achieved for reaction with 1,2‐diphenylethylenediamine (DPE) rather than with BA, therefore for simultaneous determination of 5‐HT, NE and DA in brain microdialysates, a two‐step derivatization with BA followed by DPE was developed. The detection limits for 5‐HT, NE and DA were 0.2, 0.08 and 0.13 fmol, respectively, in an injection volume of 20 µL, which corresponds to concentrations of 30, 12 and 19.5 pm, respectively in standard solution prior to derivatization. The experimental data presented demonstrate the ability of the technique to simultaneously monitor neuronally releasable pools of monoamine neurotransmitters in the rat and mouse brains at basal conditions and following pharmacological treatments or physiological stimuli. These techniques play an important role in drug discovery and clinical investigation of psychiatric and neurological diseases such as depression, schizophrenia and Parkinson's disease. Copyright © 2005 John Wiley & Sons, Ltd.
Osteoporosis and rate of bone loss among postmenopausal survivors of breast cancer
Authors: Chen Zhao , Maricic Michael , Pettinger Mary , Ritenbaugh Cheryl , Lopez Ana Maria , Barad David H. , Gass Margery , LeBoff Meryl S. , Bassford Tamsen L.
Published: August 2005

BACKGROUND

Breast cancer diagnosis and treatment may put women at higher risk for osteoporosis in later life.

METHODS

In a subgroup of participants in the Women's Health Initiative Observational Study, authors of the current study investigated differences in bone mineral density (BMD, measured by dual‐energy x‐ray absorptiometry) between breast cancer survivors (n = 209) and a noncancer reference group (n = 5759).

RESULTS

In comparison to the reference group, breast cancer survivors had significantly lower total body BMD value (0.989 vs. 1.013 g/cm2, P = 0.001) and total hip BMD value (0.823 vs. 0.845 g/cm2, P = 0.02) at baseline after adjustment for age, race/ethnicity, years since menopause, and clinical center. These lower BMD levels were largely explained by lower usage of hormone therapy (HT) among survivors: after additional statistical adjustment for HT, hip BMD values were 0.834 versus 0.844 g/cm2 (P = 0.26), and total body values were 1.005 versus 1.013 g/cm2 (P = 0.33) for survivors and reference women, respectively. More than 77% of survivors with osteoporosis were undiagnosed by their healthcare providers, and this was similar to the undiagnosed rate in the reference group (85.7%). Longitudinally, breast cancer survivors in this study did not demonstrate an accelerated rate of bone loss compared with the reference population.

CONCLUSIONS

Associated with lower HT usage, postmenopausal survivors of breast cancer were more likely to have low BMD in comparison to other women of the same age; and many of these survivors with osteoporosis were undiagnosed. Cancer 2005. © 2005 American Cancer Society.
Pigment cell distributions in different tissues of the zebrafish, with special reference to the striped pigment pattern
Authors: Hirata Masashi , Nakamura Kei‐Ichiro , Kondo Shigeru
Published: August 2005

The orderly pigment pattern of zebrafish (Danio rerio) is a good model system for studying how spatial patterns form in animals. Recent molecular genetic studies have shown that interactions between the pigment cells play major roles in pattern formation. In the present study, we performed comparative transmission electron microscopy of pigment cells, in order to clarify the structural interactions of pigment cells in tissues with and without a striped pattern. In patterned tissues, pigment cells were distributed as a one‐cell‐thick sheet. The layer order of the sheets is always kept strictly. In tissues without a striped pattern, the layer order was often disturbed or the cells were distributed in a scattered, double‐sheeted, or an accumulated pile. Our observations suggest that the underlying mechanism that controls the vertical order of the pigment cells is related to that controlling the stripe pattern. Developmental Dynamics 234:293–300, 2005. © 2005 Wiley‐Liss, Inc.
Neuropilin‐1a is involved in trunk motor axon outgrowth in embryonic zebrafish
Authors: Feldner Julia , Becker Thomas , Goishi Katsutoshi , Schweitzer Jörn , Lee Percy , Schachner Melitta , Klagsbrun Michael , Becker Catherina G.
Published: August 2005

Neuropilin‐1, a receptor for axon‐repellent semaphorins and vascular endothelial growth factor (VEGF), functions both in angiogenesis and axon growth. Here, we show strong expression of neuropilin‐1a in primary motor neurons in the trunk of embryonic zebrafish. Reducing the expression of neuropilin‐1a using antisense morpholino oligonucleotides induced aberrant branching of motor nerves, additional exit points of motor nerves from the spinal cord, and migration of neurons out of the spinal cord along the motor axon pathway in a dose‐dependent manner. These phenotypes could be partially rescued by coinjecting neuropilin‐1a mRNA. Other axons in the spinal cord and head appeared unaffected by the morpholino treatment. In addition, neuropilin‐1a morpholino treatment disturbed normal formation of blood vessels in the trunk of 24 hours postfertilization embryos, as shown by microangiography. Morpholinos to VEGF also disturbed formation of blood vessels but did not affect motor axons, indicating that correct formation of blood vessels is not needed for the growth of primary motor axons. Morpholinos to the semaphorin 3A homologs semaphorin 3A1 and semaphorin 3A2 also had no effect on motor axon growth. However, combined injections of neuropilin‐1a morpholino, at a concentration that did not elicit axonal aberrations when injected alone, with VEGF, semaphorin 3A1, or semaphorin 3A2 morpholinos synergistically increased the proportion of embryos showing aberrant motor axon growth. Thus, neuropilin‐1a in primary motor neurons may integrate signals from several ligands and is needed for proper segmental growth of primary motor nerves in zebrafish. Developmental Dynamics 234:535–549, 2005. © 2005 Wiley‐Liss, Inc.
Quantum dots are powerful multipurpose vital labeling agents in zebrafish embryos
Authors: Rieger Sandra , Kulkarni Rajan P. , Darcy Dan , Fraser Scott E. , Köster Reinhard W.
Published: August 2005

Recently, inorganic fluorescent contrast agents composed of semiconductor materials have been introduced to biological imaging approaches. These so‐called quantum dots provide unique and promising properties unreached by organic fluorophores, but their use as contrast agents within live organisms has been limited, probably due in part to concerns about their in vivo tolerance. Using transparent zebrafish embryos, we challenged quantum dots with a series of intravital imaging problems. We show that quantum dots provide a high fluorescent yield within targeted tissues, possess immense photostability, can be targeted to specific subcellular compartments, remain within targeted cells as lineage tracers, are easily separable from conventional organic fluorescent dyes, and are fixable, allowing them to be used in combination with immunohistochemistry after live recordings. Thus, quantum dots combine the specific advantages of different organic fluorescent contrast agents and promise to become the first fluorophore feasible for long‐lasting intravital time‐lapse studies. Finally, we show by colabeling blood vessels of the vasculature and major axon tracts of the nervous system that, for establishing these networks, the same guidance cues might be used in some body parts, whereas in others, both networks appear to develop independently from one another. Thus, the bright fluorescence of quantum dots will help to unravel many open questions in the fields of embryology, cell biology, as well as phenotyping and disease diagnosis. Developmental Dynamics 234:670–681, 2005. © 2005 Wiley‐Liss, Inc.
Tenascin‐C is involved in motor axon outgrowth in the trunk of developing zebrafish
Authors: Schweitzer Jörn , Becker Thomas , Lefebvre Julie , Granato Michael , Schachner Melitta , Becker Catherina G.
Published: August 2005

Motor axons in the trunk of the developing zebrafish exit from the ventral spinal cord in one ventral root per hemisegment and grow on a common path toward the region of the horizontal myoseptum, where they select their specific pathways. Tenascin‐C, a component of the extracellular matrix, is concentrated in this choice region. Adaxial cells and other myotomal cells express tenascin‐C mRNA, suggesting that these cells are the source of tenascin‐C protein. Overexpressing an axon repellent fragment containing the cysteine‐rich region and the epidermal growth factor‐like repeats of tenascin‐C led to retarded growth of ventral motor nerves between their spinal exit point and the horizontal myoseptum. Injection of a protein fragment containing the same part of tenascin‐C also induced slower growth of motor nerves. Conversely, knock down of tenascin‐C protein resulted in abnormal lateral branching of ventral motor nerves. In the zebrafish unplugged mutant, in which axons display pathfinding defects in the region of the horizontal myoseptum, tenascin‐C immunoreactivity was not detectable in this region, indicating an abnormal extracellular matrix in unplugged. We conclude that tenascin‐C is part of a specialized extracellular matrix in the region of the horizontal myoseptum that influences the growth of motor axons. Developmental Dynamics 234:550–566, 2005. © 2005 Wiley‐Liss, Inc.