bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Pelvis Angle be Monitored From Seat Support Forces in Healthy Subjects?
Authors: Geffen Paul van , Veltink Peter H. , Koopman Bart F. J. M.
Published: January 2009

Individuals who cannot functionally reposition themselves often need dynamic seating interventions that change body posture from automatic chair adjustments. Pelvis alignment directly affects sitting posture, and systems that adjust and monitor pelvis angle simultaneously might be applicable to control body posture in sitting. The present study explores whether it is feasible to monitor pelvis angle from seat support forces. Pelvis angle estimation was based on equivalent “two-force member” loading for which pelvis orientation equals the orientation of the equivalent contact force. Theoretical evaluation was done to derive important conditions for practical application. An instrumented wheelchair was developed for experimental validation in healthy subjects. Seat support forces were measured, and mechanical analysis was done to derive the equivalent contact force from which we estimated the pelvis angle. Model analysis showed a significant influence of pelvis mass, hip force, and lumbar torque on the relation between the actual pelvis angle and the predicted pelvis angle. Proper force compensation and minimal lumbar torque seemed important for accurate pelvis angle estimations. Experimental evaluation showed no body postures that involved a clear relation between the pelvis angle and the orientation of the equivalent contact force. Findings suggest that pelvis angle could not be estimated in healthy individuals under the described experimental seating conditions. Validation experiments with impaired individuals must be performed under different seating conditions to provide a better understanding whether the principle is of interest for clinical application.
Growth, Fecundity, and Energy Stores of White Sucker (Catostomus commersoni) from Lakes Containing Elevated Levels of Copper and Zinc
Authors: Munkittrick K. R. , Dixon D. G.
Published: January 2009

White sucker (Catostomus commersoni) were collected from lakes with elevated levels of both copper (13–15 μg∙L−1) and zinc (209–253 μg∙L−1) and from control lakes. In all cases the fish reached maturity between 4 and 6 yr of age, and until 6 yr of age there were no differences in length or weight of fish collected from control and contaminated lakes. After this age, fish from contaminated sites were significantly smaller and shorter than those from control sites. In addition, female sucker from contaminated lakes failed to exhibit significant increases in either length or weight after the age of maturity. The fish from contaminated lakes also exhibited decreases in egg size and fecundity, no significant increases in fecundity with age, and an increased incidence of spawning failure. The failure of female fish to grow significantly after maturity, and the decreased energetic commitment to reproduction, suggests that the food base in the contaminated lakes was limiting the performance of the female sucker. These fish exhibited decreased muscle lipid stores, decreased serum lipid levels during the postspawning period, and an apparent decrease in visceral lipid stores during the autumn. There was no effect of collection site on body stores of liver glycogen, liver lipids, serum triglycerides, or total serum cholesterol. It is known that several major food groups were missing from the sediments of contaminated lakes and that sediments under water deeper than 5 m may be incapable of supporting macroinvertebrates. Most of the alterations in sucker growth and reproduction appear to be related to nutritional deficiencies as a result of the chronic effects of elevated sediment metals on the food base of the sucker.
Long-Term Sublethal Acid Exposure in Rainbow Trout (Salmo gairdneri) in Soft Water: Effects on Ion Exchanges and Blood Chemistry
Authors: Audet Céline , Munger R. Stephen , Wood Chris M.
Published: January 2009

Long-term sublethal acid exposure (3 mo, pH 4.8) in adult rainbow trout (Salmo gairdneri) acclimated to artificial soft water (Ca2+ = 50, Na+ = 50, Cl− = 100 μeq∙L−1) caused transient net fosses of Na+ and Cl−. Net flux rates of both ions were returned to control levels after 30–52 d of acid exposure through a new equilibrium between unidirectional influx and efflux, where both were lower than control rates. K+ balance remained negative and Ca2+ balance at zero throughout the exposure. No changes in net acidic equivalent flux occurred, indicating the absence of acid–base disturbance, but ammonia excretion increased over time. Muscle K+, Na+, and Cl− fell and Ca2+ increased. Plasma Na+, Cl−, and osmolality decreased, while plasma protein, glucose, and blood hemoglobin increased during the first few weeks of acid exposure. Plasma K+ and Ca2+ did not change. General stabilization of plasma parameters occurred in concert with the stabilization of Na+ and Cl− flux rates, but no recovery to control levels was observed for any of them. We conclude that despite this stabilization at a new steady state, rainbow trout were physiologically affected in a deleterious manner by chronic sublethal acid exposure in soft water.
Littoral Zoobenthic Biomass in Lakes, and Its Relationship to Physical, Chemical, and Trophic Factors
Authors: Rasmussen Joseph B.
Published: January 2009

The hypothesis that littoral morphometry exerts a strong effect on zoobenthic biomass was tested in Lake Memphremagog, Quebec–Vermont, by regression analysis of the relationship between littoral zoobenthic biomass and littoral slope, exposure (Lake area visible from sampling site), and trophic status (micrograms of chlorophyll a per litre). Eighty-one percent of the variance in Log littoral zoobenthic biomass (LZB) could be explained by[Formula: see text]When the predictions from this relationship were compared with littoral zoobenthos estimates from other lakes, residuals were positively correlated with the calcium concentration of the water (r = 0.41) and negatively correlated with the chloride concentration (r = −0.51). The regression equation obtained for all of the sites was[Formula: see text]and explained 80% of the variation in Log LZB. Sites situated within deltas from stream inflows did not differ significantly from these that did not (ANCOVA), indicating that coarse allochthonous input from these fluvial sources was not a major factor determining littoral zoobenthic biomass in these lakes.
Influence of Nutrient Enrichment and Light Availability on the Abundance of Aquatic Macrophytes in Florida Streams
Authors: Canfield Jr. Daniel E. , Hoyer Mark V.
Published: January 2009

A survey of 17 Florida streams was conducted between October 1984 and August 1986 to determine if the abundance of aquatic macrophytes was related to nutrient enrichment. Macrophyte standing crops were not correlated with in-stream total phosphorus or total nitrogen concentrations. Aquatic macrophytes contained less than 2% of the annual nutrient discharge in nearly all streams. Nutrients are, therefore, not considered to be the primary factor regulating the abundance of aquatic macrophytes in most Florida streams. Shading by riparian vegetation seems to be the dominant factor controlling the location and abundance of aquatic macrophytes. Statistical analyses indicated that the potential average and maximum standing crop of aquatic macrophytes in the sampled streams could be estimated by the equations[Formula: see text]where SCavg and SCmax are the average and maximum standing crop of aquatic macrophytes (kilograms fresh weight per square metre), respectively, and %C is the percent canopy coverage by riparian vegetation.
Comparison of Phosphorus Dynamics in Two Oklahoma Reservoirs and a Natural Lake Varying in Abiogenic Turbidity
Authors: Heath Robert T. , Francko David A.
Published: January 2009

The rate of phosphate uptake, the immediate fate of phosphate, and the potential rate of release of phosphate from dissolved phosphorus compounds in epilimnia of two reservoirs and one natural lake in northcentral Oklahoma were compared in the summer and in the late autumn. Sangre Isle Lake is a highly productive eutrophic impoundment, Sanborn Lake is a natural lake with low phytoplanktonic productivity, and Boomer Lake is an impoundment with modest productivity that is heavily affected by clay suspensoids. Although the uptake of phosphate (radiometrically determined) was rapid in each of these lakes in summer, the fate of phosphate in Boomer Lake differed from that of the others, with much of the phosphate sorbing to suspended silts and clays rather than biota (determined by isopycnic sedimentation). Recycling of phosphate from phosphomonoesters was greatest in Sangre Isle Lake, moderate in Sanborn Lake, but was undetectable in Boomer Lake. These findings suggest that high concentrations of clay suspensoids influence the epilimnetic P dynamics in reservoirs and lakes.
Growth and Survival of Hormone-Sterilized Coho (Oncorhynchus kisutch) and Kokanee Salmon (O. nerka) in a Lacustrine Environment
Authors: Parkinson Eric A. , Tsumura Kanji
Published: January 2009

Coho (Oncorhynchus kisutch) and kokanee salmon (O. nerka) were sterilized using 17α-methyltestosterone treatments and released into a lacustrine environment. The treatment appeared to be successful and sizes at capture were similar for treated and control fish. Return rates of hormone-treated groups of fish were much lower than those of the control groups. Differences in return rates were assumed to be due to differences in survival rates but the possibility of differential vulnerability to the capture gear could not be ruled out. The proportion of treated kokanee in the catch increased with age, indicating that treated kokanee survived beyond the normal life span of the species.
A Space- and Time-Scale Characterization of Circulation and Mixing over Submarine Banks, with Application to the Northwestern Atlantic Continental Shelf
Authors: Loder John W. , Ross Charles K. , Smith Peter C.
Published: January 2009

The circulation and mixing over submarine banks is described in terms of integral space and time scales determined from Eulerian and Lagrangian currents. The time scales include the time for vertical diffusion across the pycnocline or water depth, the recirculation times of any residual gyre, and the residence time over the bank. These may be intercompared to obtain a description of a bank's physical regime and compared with the time scales associated with biological processes to identify possible physical–biological linkages. The space scales include the vertical diffusion distance during a time interval and the excursions associated with horizontal current fluctuations. These may be compared with topographically imposed and biologial space scales. The integral-scale characterization is applied to four northwestern Atlantic banks. The data suggest that the vertical diffusion time is longer than the recirculation and residence times of the surface water on Flemish Cap, shorter on Browns and Georges Banks, and comparable with the Southeast Shoal residence time; the recirculation time is greater than the residence time of the near-surface water on all banks except Georges and the western cap of Browns Bank; and the cross-bank excursions are much less than the bank radius on all except Browns Bank.
Fish Assemblage Stability in a Southern Appalachian Stream
Authors: Freeman M. C. , Crawford M. K. , Barrett J. C. , Facey D. E. , Flood M. G. , Hill J. , Stouder D. J. , Grossman G. D.
Published: January 2009

We monitored fish populations at three sites in a southern Appalachian stream system during a 40-mo study. Assemblages at two sites, consisting of four and five resident species, were persistent in terms of relative species abundances and production. This persistence was related to low variation in abundance of the two numerically dominant fishes, mottled sculpins (Cottus bairdi) and longnose dace (Rhinichthys cataractae). Less abundant residents, rosyside dace (Clinostomus funduloides), rainbow trout (Salmo gairdneri), and greenside darters (Etheostoma blennioides), displayed lower levels of persistence. We also observed pronounced annual variation in either young-of-the-year recruitment and/or subsequent year-class strength of four resident species, possibly resulting from a severe drought during the third year of study. Abundance and production of rosyside dace and trout were greatly affected by fluctuations in recruitment and year-class strength, suggesting that environmental variability strongly influenced these populations. Density-dependent mechanisms may have regulated sculpin and longnose dace populations. The three-species asssemblage at a third site also was persistent as a result of relatively stable sculpin and longnose dace populations, whereas the rainbow trout population fluctuated among years. We observed significant intersite differences in relative year-class strength in a given year and in population structures of sculpins and longnose dace, suggesting that spatial variation in habitat characteristics affected assemblage dynamics and responses to environmental fluctuations.
What is a Safe Level of Polycyclic Aromatic Hydrocarbons for Fish: Subchronic Toxicity Study on Winter Flounder (Pseudopleuronectes americanus)
Authors: Payne Jerry F. , Kiceniuk J. , Fancey L. L. , Williams U. , Fletcher G. L. , Rahimtula A. , Fowler B.
Published: January 2009

Dose–response relationships were evaluated for a variety of biological and biochemical indices in a subchronic toxicity study with winter flounder (Pseudopleuronectes americanus) exposed to sediments contaminated with a petroleum source of polycyclic aromatic hydrocarbons (PAH). Indices investigated were biologically meaningful and included muscle and liver levels of energy reserves, organ weight – body weight relationships, and general condition indices. Results support the hypothesis that many point sources of sediment hydrocarbon contamination worldwide could be harmful to fish health. Biochemical effects such as change in mixed-function oxygenase (MFO) enzyme levels and fat content of liver were altered at very low hydrocarbon levels (~1.0 μg/g), levels that we reason will likely be found in sediments over much wider geographical areas than polluted harbors, or oil development and sewage outfall sites. We hypothesized that hydrocarbons in both coastal waters and food species may often occur in sufficient concentrations to affect biological responses in fish. The fact that very low levels of hydrocarbons in sediments, water, or foods may produce biological responses in fish attests to the importance of developing criteria for assessing the toxicological significance of sublethal effects or otherwise defining genuine harmful effects in contrast with effects per se.
Particulate Organic Matter Export from Three Headwater Streams: Discrete versus Continuous Measurements
Authors: Cuffney Thomas F. , Wallace J. Bruce
Published: January 2009

Particulate organic matter (POM) export from three small headwater streams of the southern Appalachian Mountains was estimated using continuous and discrete (grab) measurement methods for 2 yr. Total annual POM export estimated from continuous measurements was always greater (28–68 kg ash-free dry mass (AFDM)) than estimates (8–44 kg AFDM) made from discrete measurements (i.e. POM concentration × total discharge). Continuous export samples were collected using a weir and gaging flume connected to a Coshocton proportional sampler designed to deliver 0.6% of discharge into a series of three settling barrels. The settling barrels removed a consistent proportion of POM (85–87%). The proportion of stream flow sampled by the Coshocton samplers was constant for each of the samplers (range 0.53–0.6%). The constant extraction efficiencies and proportional sampling of discharge allowed for the calculation of total export independent of discharge measurements (i.e. total export = amount in barrels ÷ extraction efficiency ÷ Coshocton percentage). The inability of the discrete method to adequately sample storm and bedload transport accounts for the underestimates of total annual export. This underestimation has important implications for studies which use discrete measurements to estimate POM export.
Sediment Control of Soluble Reactive Phosphorus in Hoxie Gorge Creek, New York
Authors: Klotz R. L.
Published: January 2009

Stream sediments were found to regulate the soluble reactive phosphorus (SRP) of stream water by geochemical processes. This conclusion was based on sediment analysis, laboratory sorption experiments, and measurement of the equilibrium phosphorus concentration (EPC). EPC is the concentration of P in the water at which there is neither sorption nor desorption of P by the sediments. At low flow conditions, streamwater SRP was highly correlated with EPC at six sites along Hoxie Gorge Creek (r = 0.979). EPC was inversely related to the ionic strength of the equilibrating solution, with Ca2+ producing larger changes than Na+. Minimum EPC values occurred near the neutral pH of the stream water and increased sharply in acidic and basic solutions. Also, EPC was negatively correlated with the exchangeable Al content of the sediments at the six sites. These data are consistent with a mechanism previously verified for soils in which solution cations displace exchangeable Al(III) from sediments; hydrolyzed Al(III) reacts with phosphate and removes it from solution. EPC and streamwater SRP were lower at sites with sediments that had higher concentrations of P-binding sites, despite also having higher sediment P.
Evidence of Introgressive Hybridization in the GenusStizostedion: Interspecific Transfer of Mitochondrial DNA between Sauger and Walleye
Authors: Billington Neil , Hebert Paul D. N. , Ward Robert D.
Published: January 2009

The mitochondrial genotypes of walleye (Stizostedion vitreum) and sauger (Stizostedion canadense) are readily differentiated, permitting an analysis of the incidence of hybridization between the taxa. We provide evidence that introgression of sauger into walleye has occurred: two female walleye collected from Lake Simcoe contained a mitochondrial genome identical to that of sauger. Not only were these two fish morphologically indistinguishable from typical walleye, they were homozygous for the diagnostic alleles characteristic of walleye at the Mdh-3 and Pgm-1 allozyme loci. Sauger have not been recorded in Lake Simcoe, but a few individuals may have been inadvertently introduced during stocking programs and introgressed with walleye due to a lack of conspecific mates.
Salmon Management and the Search for Values
Authors: Scarnecchia Dennis L.
Published: January 2009

This perspective addresses the role of human values in North American salmon management. Salmon resources have been aided and harmed by technology, and managers must carefully assess how current and future technologies will be used to manage salmon. Effective managers must be knowledgeable of fishery science and human values. The science in fishery management is the objective, logical, and systematic method of obtaining reliable knowledge about fishery resources. The art in fishery management involves our values, that is, what we judge to be good, desirable, and important in the long run. A rational management plan is a selective embodiment of the values of the manager or of the organization or society that the manager represents. More surveys are needed to assess the values of the public toward salmon resources. Several potentially desirable directions are discussed for future salmon management in the Pacific Northwest.
Locomotion of marine invertebrate larvae: a review
Authors: Chia Fu-Shiang , Buckland-Nicks John , Young Craig M.
Published: January 2009

Marine invertebrate larvae swim by using cilia or muscles, or a combination of these. The effectiveness of cilia as locomotory organelles diminishes with increasing body size above 1 mm. Thus, larvae propelled by cilia are small and, owing to the small Reynold's numbers that operate in this size range, their movements are governed by viscous forces rather than inertial ones. Cilia may be distributed uniformly over the surface of the larva and (or) localized on rings, bands, arms, or lobes. During development the pattern of ciliation may change; this often increases the swimming ability of the larva, particularly its manoeuverability. In many cases, redistribution of cilia coincides with the onset of feeding behavior. The locomotory currents produced by ciliary beating or the action of swimming appendages may simultaneously convey food particles to the mouth. Muscles may have enabled some larvae to exceed the size limit imposed by ciliary propulsion and also have enabled greater swimming speeds. Invertebrate larvae that use muscular locomotion possess some form of skeleton (hydrostatic, exoskeleton. or notochord) to provide the necessary resistance for muscular contraction. The density of most marine invertebrate larvae exceeds that of seawater, therefore, they must swim to stay suspended. A wide variety of parachute structures, density-reducing devices, and passive hydrodynamic mechanisms counteract the sedimenting effects of gravity. The timing of development in some larvae is such that when the tendency to sink exceeds the ability to swim, the larva is preparing for settlement and metamorphosis.
Behavioural thermoregulation in wintering black ducks: roosting and resting
Authors: Brodsky Lynn M. , Weatherhead Patrick J.
Published: January 2009

Black ducks (Anas rubripes) wintering near Ottawa, Canada, used a variety of behaviours to reduce their energy costs. The roost site that they occupied provided greater protection from wind than the feeding site, with the consequent reduction in forced convective heat loss. Time spent at the feeding site (i.e., away from the roost) varied with temperature such that ducks maximized their time at the roost on the coldest days. This relationship was facilitated by the ducks' food supply (cracked corn replenished daily), which precluded extending foraging time to increase food intake in cold weather. At the roost ducks huddled in colder weather and adopted postures that reduced both the nonfeathered area exposed to the air and also the surface to volume ratio. The ducks preferentially faced toward the sun and into the wind, but when these were in opposite directions they faced the sun only when wind speed was low.
Growth in the first summer of life: a comparisson of nine co-occurring fish species
Authors: Keast Allen , Eadie J.
Published: January 2009

Growth in the first summer of life was compared in nine coexisting fish species with different life history strategies. Relative to hatching size, the various species grew 6- to 10-fold in length and up to 1000-fold in weight. Growth patterns were similar among species; length increments were linear early in the summer and reached a plateau by early September. Few species grew significantly in length or weight beyond September. There were also few appreciable differences in length–weight regressions among species, and in all cases growth was isometric. Spawning date had the greatest influence on the amount of growth attained, with early spawners achieving a greater mean length and weight than late spawners. Adult size did not influence the amount of growth; large-bodied species achieved proportionately less of their adult weight and length in the first summer than did small species. However, adult size did influence the duration of the spawning period. Small-bodied species had the most protracted spawning seasons and the greatest size range of young at the end of the summer. There was no apparent relationship between diet type and growth in young fish.
The life history of Philocasca alba (Trichoptera: Limnephilidae) in a Rocky Mountain stream
Authors: Mutch R. A. , Pritchard G.
Published: January 2009

The life cycle of Philocasca alba Nimmo spans 3 years in a cold, second order, subalpine stream in the Rocky Mountains of Alberta. The flight period was from mid-May to late July. Larval instar 1 was found only in August–September; all other four instars were present in samples throughout most of the year. In their third autumn in the stream larvae in the final instar burrowed into gravel, pupated, and overwintered. Growth was confined to the ice-free period, June to November, when larval densities were greatest among deposits of conifer needles, cones, and woody material in pools. Larvae from these detrital accumulations had mainly fragments of conifer needles in their guts, although laboratory experiments showed that larvae could feed and grow on conifer needles only if they were highly conditioned. The later instars, particularly instar V, constituted a much greater than expected proportion of total larvae among submerged bank vegetation in spring and summer and deciduous leaves in autumn. Larvae in these two microhabitats mainly had fragments of moss and fragments of leaves, respectively, in their guts. The importance of moss was confirmed by a field experiment which showed that fifth instar larvae had significantly faster growth rates when fed on detritus supplemented with bank moss than detritus alone or detritus supplemented with deciduous leaves during the autumn.
The introduced aquatic macrophyte, Myriophyllum spicatum, as habitat for fish and their invertebrate prey
Authors: Keast Allen
Published: January 2009

The exotic macrophyte Myriophyllum spicatum spread widely in Lake Opinicon, Ontario, after 1974, dominating the 2.0- to 3.5-m depth zone which had previously been largely open water. In the shallows it formed beds within the species-rich native Potamogeton–Vallisneria community. This paper compares fish and prey-invertebrate abundance and distribution (i) before and after the milfoil invasion for a series of depth zones (1972 relative to 1979–1980), and (ii) in communities of M. spicatum relative to native macrophytes in the littoral zone shallows in the summer of 1980. At a depth of 2.0–3.5 m (major M. spicatum zone), there were significantly fewer bluegill but more black crappie and golden shiner in 1979–1980 compared with 1972, and significantly fewer isopods, chironomid and trichopteran larvae, and ephemeropteran nymphs. Differences were greatest in late summer. Inshore and offshore from the M. spicatum zone, differences were minor, suggesting that the invader, not time, was responsible. At a 1.0- to 1.3-m depth in the summer of 1980, three to four times as many fish occurred during the daytime feeding period in the Potamogeton–Vallisneria community than in the M. spicatum area. In the benthos, beneath the native beds, five major taxa of prey invertebrates were three to seven times more abundant. The foliage of Potamogeton plus Vallisneria supported twice as many invertebrates per square metre in late summer than did M. spicatum. Insect emergences over the summer (May–September) were twice as high. Up to the present, the net impact of the habitat change on the fish populations of Lake Opinicon has not been great. If in the future M. spicatum were to replace the rich native macrophyte beds in the shallows, this would be cause for concern.
The adaptive significance of dorsal spine variation in the fourspine stickleback, Apeltes quadracus. II. Phenotype–environment correlations
Authors: Blouw D. M. , Hagen D. W.
Published: January 2009

The fourspine stickleback (Apeltes quadracus) is polymorphic for dorsal spine number, the variation is heritable, and morph frequencies are highly differentiated geographically. Our purpose here is to determine how spines vary in relation to environment. Dorsal spine number is significantly correlated (P < 0.001) with environmental differences among sites; the environmental correlates include predators, potential competitors, vegetation, physical environment, habitat, and geographical position. Based on these correlations we hypothesize that selection by predators favours the higher spined morphs and that selection by competitors favours the lower spined morphs. The correlations with other environmental variables probably reflect interactions with predation and (or) competition, but they may be concomitants of independent and unidentified selective agents. The observed patterns of geographic variation in spine number are in agreement with those expected if predators and competitors are selective agents. We conclude that selection acts on this polymorphism; the geographic differentiation in spine number is adaptive.
Comparative resistance of Oregon (Big Creek) and British Columbia (Capilano) juvenile chinook salmon to the myxozoan pathogen, Ceratomyxa shasta, after laboratory exposure to Fraser River water
Authors: Ching Hilda Lei
Published: January 2009

In a laboratory experiment conducted in the fall 1983, Oregon (Big Creek) and British Columbia (Capilano) hatchery Chinook salmon were exposed to Fraser River water containing the infectious stage of the myxozoan pathogen, Ceratomyxa shasta. The juvenile fish were exposed for 10 days in 370 L of water (74 L replaced every other day for 5 days). While only 1 of 21 Big Creek fish became infected, all 20 of the Capilano fish died of C. shasta within 40 days. The Big Creek fish demonstrated high resistance to the parasite while the Capilano fish had low resistance. These results were similar to those from field exposures in previous studies.
Daily feeding site use of urban pigeons
Authors: Lefebvre Louis , Giraldeau Luc-Alain
Published: January 2009

Small flocks (20–40 individuals) of feral rock doves (Columba livia) studied in downtown Montréal follow a bimodal daily schedule of feeding site attendance. The bimodal schedule is achieved through a summation of different usage schedules in the various areas of the sites. The latter schedules are not necessarily bimodal and reveal clear differences between individuals that otherwise share some common feeding areas. The existence of these individual differences has implications for two of the mechanisms by which flock feeding may benefit birds, information centres, and the skill pool.
The effect of extracellular calcium and preload on a teleost heart during extracellular hypercapnic acidosis
Authors: Farrell A. P. , Hart T. , Wood S. , Driedzic W. R.
Published: January 2009

The effect of extracellular calcium ([Ca2+]e) on the performance of the in situ perfused sea raven heart was evaluated under nonacidotic, acidotic, and high work load conditions. Increases in [Ca2+]e improved power output of the nonacidotic heart and restored control levels of power output to the heart exposed to hypercapnic acidosis (1.8% CO2, pH 7.4). Extracellular acidosis severely curtailed the scope for cardiac work (increased cardiac output and afterload), and only a 50% increase in the control, nonacidotic power output was possible with increases in preload and saturating levels of [Formula: see text]. It is suggested that increases in preload are probably more important than increases in [Ca2+]e to improve cardiac performance in the seas raven heart during extracellular acidosis.
SELF-ORGANISING MIXTURE AUTOREGRESSIVE MODEL FOR NON-STATIONARY TIME SERIES MODELLING
Authors: NI HE , YIN HUJUN
Published: January 2009

Modelling non-stationary time series has been a difficult task for both parametric and nonparametric methods. One promising solution is to combine the flexibility of nonparametric models with the simplicity of parametric models. In this paper, the self-organising mixture autoregressive (SOMAR) network is adopted as a such mixture model. It breaks time series into underlying segments and at the same time fits local linear regressive models to the clusters of segments. In such a way, a global non-stationary time series is represented by a dynamic set of local linear regressive models. Neural gas is used for a more flexible structure of the mixture model. Furthermore, a new similarity measure has been introduced in the self-organising network to better quantify the similarity of time series segments. The network can be used naturally in modelling and forecasting non-stationary time series. Experiments on artificial, benchmark time series (e.g. Mackey-Glass) and real-world data (e.g. numbers of sunspots and Forex rates) are presented and the results show that the proposed SOMAR network is effective and superior to other similar approaches.
BIOLOGICALLY PLAUSIBLE BSDT RECOGNITION OF COMPLEX IMAGES: THE CASE OF HUMAN FACES
Authors: GOPYCH PETRO
Published: January 2009

On the basis of recent binary signal detection theory (BSDT), optimal recognition algorithms for complex images are constructed and their optimal performance are calculated. A methodology for comparing BSDT predictions and measured human performance is developed and applied to explaining particular face recognition experiment. The BSDT makes possible computer codes with recognition performance better than that in humans, its fundamental discreteness is consistent with the experiment. Related neurobiological and behavioral effects are briefly discussed.
FUZZY COGNITIVE MAPS FOR PATTERN RECOGNITION APPLICATIONS
Authors: PAPAKOSTAS G. A. , BOUTALIS Y. S. , KOULOURIOTIS D. E. , MERTZIOS B. G.
Published: January 2009

A first attempt to incorporate Fuzzy Cognitive Maps (FCMs), in pattern classification applications is performed in this paper. Fuzzy Cognitive Maps, as an illustrative causative representation of modeling and manipulation of complex systems, can be used to model the behavior of any system. By transforming a pattern classification problem into a problem of discovering the way the sets of patterns interact with each other and with the classes that they belong to, we could describe the problem in terms of Fuzzy Cognitive Maps. More precisely, some FCM architectures are introduced and studied with respect to their pattern recognition abilities. An efficient novel hybrid classifier is proposed as an alternative classification structure, which exploits both neural networks and FCMs to ensure improved classification capabilities. Appropriate experiments with four well-known benchmark classification problems and a typical computer vision application establish the usefulness of the Fuzzy Cognitive Maps, in a pattern recognition research field. Moreover, the present paper introduces the use of more flexible FCMs by incorporating nodes with adaptively adjusted activation functions. This advanced feature gives more degrees of freedom in the FCM structure to learn and store knowledge, as needed in pattern recognition tasks.
DECENTRALIZED ROBUST CONTROL WITH GUARANTEED COST FOR HYBRID COMPLEX NETWORKS
Authors: ZHANG HAO , CHEN QIJUN , YAN HUAICHENG
Published: January 2009

In this paper, robust control of the decentralized guaranteed cost was studied for a class of complex network with impulsive effects and nonlinear perturbation. Based on the Lyapunov stability theorem, sufficient conditions for the decentralized guaranteed cost controllers were obtained. The design method of the decentralized guaranteed cost control law was given by solving a parameter-dependent Riccati matrix equation. An example is given to illustrate the effectiveness of the presented scheme.
DYNAMIC TOPOLOGICAL VISUALIZATION OF CHANGE IN PERCEPTUAL INFORMATION OF PARTNER ROBOTS
Authors: KUBOTA NAOYUKI , KOJIMA HIROYUKI , AIZAWA NAOHIDE , TANG DALAI
Published: January 2009

This paper proposes a method for topologically visualizing the perceptual information of a partner robot. First, we explain the methods for human detection, human motion extraction, and object recognition. Next, we explain the perceptual system of the robot based on the detected human and objects. We propose a topological visualization method based on a spring-mass-damper system according to the perceptual information. Finally, we show several experimental results of the proposed method, and the proposed method enables a human to understand what the robot perceives in the interaction with the human and environment.
SHAPE TRANSFORMATIONS OF VESICLES BUILT OF AMPHIPHILIC MOLECULES
Authors: GÓŹDŹ W. T.
Published: January 2009

We review our recent work on the shape transformations of vesicles subject to external stimuli. Possible shape transformations resulting from the change of the spontaneous curvature, volume, or composition of the components on the surface of a vesicle are examined within the framework of the spontaneus curvature model. The influence of encapsulated or adhered rigid object such as microtubules or colloidal particles on the shape transformation is also investigated. A few cases of shape transformations encountered in experiments are described.
Evidence-Based Public Health: A Fundamental Concept for Public Health Practice
Authors: Brownson Ross C. , Fielding Jonathan E. , Maylahn Christopher M.
Published: January 2009

Despite the many accomplishments of public health, a greater attention to evidence-based approaches is warranted. This article reviews the concepts of evidence-based public health (EBPH), on which formal discourse originated about a decade ago. Key components of EBPH include making decisions on the basis of the best available scientific evidence, using data and information systems systematically, applying program-planning frameworks, engaging the community in decision making, conducting sound evaluation, and disseminating what is learned. Three types of evidence have been presented on the causes of diseases and the magnitude of risk factors, the relative impact of specific interventions, and how and under which contextual conditions interventions were implemented. Analytic tools (e.g., systematic reviews, economic evaluation) can be useful in accelerating the uptake of EBPH. Challenges and opportunities (e.g., political issues, training needs) for disseminating EBPH are reviewed. The concepts of EBPH outlined in this article hold promise to better bridge evidence and practice.
Geographic Life Environments and Coronary Heart Disease: A Literature Review, Theoretical Contributions, Methodological Updates, and a Research Agenda
Authors: Chaix Basile
Published: January 2009

A growing literature investigates associations between neighborhood social environments and coronary heart disease (CHD). After reviewing the literature, we present a theoretical model of the mechanisms through which geographic life environments may influence CHD, focusing particularly on the social-interactional environment. We suggest that, in addition to the common notions of social cohesion or fragmentation and social disorder, eco-epidemiologists should consider neighborhood identities and stigmatization processes. We posit that neighborhood social interactions affect the wide set of affective, cognitive, and relational experiences individuals have in their neighborhoods, which in turn influence the psycho-cognitive antecedents of behavior and in the end shape health behavior. Finally, we discuss key methodological challenges relevant to the advent of a new generation of neighborhood studies, including the operational definition of neighborhoods, nonresidential environments, ecometric measurement, model specification strategies, mediational models, selection processes and notions of empirical/structural confounding, and the relevance of observational versus interventional studies.
Effects of palmitate on ER and cytosolic Ca2+homeostasis in β-cells
Authors: Gwiazda Kamila S. , Yang Ting-Lin B. , Lin Yalin , Johnson James D.
Published: January 2009

There are strong links between obesity, elevated free fatty acids, and type 2 diabetes. Specifically, the saturated fatty acid palmitate has pleiotropic effects on β-cell function and survival. In the present study, we sought to determine the mechanism by which palmitate affects intracellular Ca2+, and in particular the role of the endoplasmic reticulum (ER). In human β-cells and MIN6 cells, palmitate rapidly increased cytosolic Ca2+through a combination of Ca2+store release and extracellular Ca2+influx. Palmitate caused a reversible lowering of ER Ca2+, measured directly with the fluorescent protein-based ER Ca2+sensor D1ER. Using another genetically encoded indicator, we observed long-lasting oscillations of cytosolic Ca2+in palmitate-treated cells. In keeping with this observed ER Ca2+depletion, palmitate induced rapid phosphorylation of the ER Ca2+sensor protein kinase R-like ER kinase (PERK) and subsequently ER stress and β-cell death. We detected little palmitate-induced insulin secretion, suggesting that these Ca2+signals are poorly coupled to exocytosis. In summary, we have characterized Ca2+-dependent mechanisms involved in altered β-cell function and survival induced by the free fatty acid palmitate. We present the first direct evidence that free fatty acids reduce ER Ca2+and shed light on pathways involved in lipotoxicity and the pathogenesis of type 2 diabetes.
Targeted overexpression of the two colony-stimulating factor-1 isoforms in osteoblasts differentially affects bone loss in ovariectomized mice
Authors: Yao Gang-Qing , Wu Jian-Jun , Ovadia Shira , Troiano Nancy , Sun Ben Hua , Insogna Karl
Published: January 2009

Colony-stimulating factor-1 (CSF1) is one of two cytokines required for normal osteoclastogenesis. There are two major isoforms of CSF1, the cell-surface or membrane-bound isoform (mCSF1) and soluble CSF1 (sCSF1). Whether these isoforms serve nonredundant functions in bone is unclear. To explore this question, we generated transgenic mice expressing human sCSF1, human mCSF1, or both (s/mCSF1) in osteoblasts using the 2.3-kb rat αI-collagen promoter. Bone density determined by peripheral quantitative computed tomography was significantly reduced in mCSF1, sCSF1, and s/mCSF1 transgenic mice compared with wild-type animals. When analyzed by sex, sCSF1, and s/mCSF1, female animals but not mCSF1 female mice were found to have greater bone loss than their male littermates (−20 vs. −9.2%; P < 0.05 for sCSF1 and −21.6 vs. −11.2% for s/mCSF1; P < 0.01). By breeding CSF1 isoform-selective transgenic mice to an op/op background, mice were generated in which a single CSF1 isoform was the only source of the cytokine (sCSF1op/opand mCSF1op/op). Unlike osteoblast-targeted overexpression of mCSF1, selective transgenic expression of sCSF1 did not completely correct the op/op phenotype in 5-mo-old animals. Interestingly, compared with sham-ovariectomized mice of the same genotype, ovariectomy in sCSF1op/opmice led to a greater loss of spinal bone mineral density (22.1%) than was seen in either mCSF1op/opmice (12.9%) or in wild-type animals (10.9%). Our findings support the conclusion that sCSF1 and mCSF1 serve nonredundant functions in bone and that sCSF1 may play a role in mediating estrogen-deficiency bone loss.
Tissue methionine cycle activity and homocysteine metabolism in female rats: impact of dietary methionine and folate plus choline
Authors: Wilson Fiona A. , van den Borne Joost J. G. C. , Calder A. Graham , O'Kennedy Niamh , Holtrop Grietje , Rees William D. , Lobley Gerald E.
Published: January 2009

Impaired transfer of methyl groups via the methionine cycle leads to plasma hyperhomocysteinemia. The tissue sources of plasma homocysteine in vivo have not been quantified nor whether hyperhomocysteinemia is due to increased entry or decreased removal. These issues were addressed in female rats offered diets with either adequate or excess methionine (additional methyl groups) with or without folate and choline (impaired methyl group transfer) for 5 wk. Whole body and tissue metabolism was measured based on isotopomer analysis following infusion with either [1-13C,methyl-2H3]methionine or [U-13C]methionine plus [1-13C]homocysteine. Although the fraction of intracellular methionine derived from methylation of homocysteine was highest in liver (0.18–0.21), most was retained. In contrast, the pancreas exported to plasma more of methionine synthesized de novo. The pancreas also exported homocysteine to plasma, and this matched the contribution from liver. Synthesis of methionine from homocysteine was reduced in most tissues with excess methionine supply and was also lowered in liver ( P < 0.01) with diets devoid of folate and choline. Plasma homocysteine concentration ( P < 0.001) and flux ( P = 0.001) increased with folate plus choline deficiency, although the latter still represented <12% of estimated tissue production. Hyperhomocysteinemia also increased ( P < 0.01) the inflow of homocysteine into most tissues, including heart. These findings indicate that a full understanding of hyperhomocysteinemia needs to include metabolism in a variety of organs, rather than an exclusive focus on the liver. Furthermore, the high influx of homocysteine into cardiac tissue may relate to the known association between homocysteinemia and hypertension.
Nitric oxide sensitive-guanylyl cyclase subunit expression changes during estrous cycle in anterior pituitary glands
Authors: Cabilla Jimena P. , Ronchetti Sonia A. , Nudler Silvana I. , Miler Eliana A. , Quinteros Fernanda A. , Duvilanski Beatriz H.
Published: January 2009

17β-Estradiol (E2) exerts inhibitory actions on the nitric oxide pathway in rat adult pituitary glands. Previously, we reported that in vivo E2acute treatment had opposite effects on soluble guanylyl cyclase (sGC) subunits, increasing α1- and decreasing β1-subunit protein and mRNA expression and decreasing sGC activity in immature rats. Here we studied the E2effect on sGC protein and mRNA expression in anterior pituitary gland from adult female rats to address whether the maturation of the hypothalamus-pituitary axis influences its effects and to corroborate whether these effects occur in physiological conditions such as during estrous cycle. E2administration causes the same effect on sGC as seen in immature rats, and these effects are estrogen receptor dependent. These results suggest that E2is the main effector of these changes. Since the sGC α-subunit increases while the sGC activity decreases, we studied if other less active isoforms of the sGC α-subunit are expressed. Here we show for the first time that sGCα2and sGCα2inhibitory (α2i) isoforms are expressed in this gland, but only sGCα2imRNA increased after E2acute treatment. Finally, to test whether E2effects take place under a physiological condition, sGC subunit expression was monitored over estrous cycle. sGCα1, -β1, and -α2ifluctuate along estrous cycle, and these changes are directly related with E2level fluctuations rather than to NO level variations. These findings show that E2physiologically regulates sGC expression and highlight a novel mechanism by which E2downregulates sGC activity in rat anterior pituitary gland.
Stimulation of skeletal muscle myofibrillar protein synthesis, p70 S6 kinase phosphorylation, and ribosomal protein S6 phosphorylation by inhibition of myostatin in mature mice
Authors: Welle Stephen , Burgess Kerri , Mehta Sangeeta
Published: January 2009

Knocking out myostatin activity during development increases the rate of muscle protein synthesis. The present study was done to determine whether postdevelopmental loss of myostatin activity stimulates myofibrillar protein synthesis and the phosphorylation of some of the proteins involved in regulation of protein synthesis rate. Myostatin activity was inhibited for 4 days, in 4- to 5-mo-old male mice, with injections of an anti-myostatin antibody (JA16). The mean myofibrillar synthesis rate increased 19% ( P < 0.01) relative to the mean rate in saline-treated mice, as determined by incorporation of deuterium-labeled phenylalanine. JA16 increased phosphorylation of p70 S6 kinase (S6K) and ribosomal protein S6 (rpS6) 1.9-fold ( P < 0.05). It did not affect phosphorylation of eukaryotic initiation factor 4E-binding protein-1 or Akt. Microarrays and real-time PCR analyses indicated that JA16 administration did not selectively enrich levels of mRNAs encoding myofibrillar proteins, ribosomal proteins, or translation initiation and elongation factors. Rapamycin treatment did not affect the rate of myofibrillar protein synthesis whether or not the mice received JA16 injections, although it eliminated the phosphorylation of S6K and rpS6. We conclude that the normal level of myostatin activity in mature muscle is sufficient to inhibit myofibrillar synthesis rate and phosphorylation of S6K and rpS6. Reversal of the inhibition of myofibrillar synthesis with an anti-myostatin antibody is not dependent on mTOR activation.