bluuebunny/crossref_metadata_2025 huggingface dataset:
A framework to proactively consider road safety within the road planning process
Authors: de Leur Paul , Sayed Tarek
Published: September 2003

All too often, engineering strategies aimed at improving road safety are reactions to existing problems that occur after a road has been designed and built. Targeting problem locations and developing plans to reduce collisions are vital and have proven to be very successful. Transportation professionals, however, should also take a proactive approach to address road safety before problems emerge. This paper describes an evolving need of how to deal with road safety in a proactive manner. Although a proactive approach should improve the overall safety performance, there is currently a poor understanding of how to proactively plan for road safety. Several logistical and technical obstacles hinder the effective planning for road safety. Each of these obstacles is presented in detail, followed by a description of the opportunity to overcome each obstacle. The paper also includes the results of a case study used to demonstrate the proposed process. A proactive approach to road safety complements traditional, reactive methods currently in use. Significant progress will be realized once safety professionals shift their focus from fixing existing problems to helping plan roads that attempt to be problem free. The net result should be a safer road system.Key words: proactive road safety, safety audits, safety planning, safety evaluation, safety improvements.
Analyse du comportement des assemblages boulonnés par platine d'extrémité sollicités en traction
Authors: Mimoune Mostefa , Mimoune Fatima Z
Published: September 2003

This article presents an experimental study on bolted T-shaped end plate connectors subjected to a static load. Testing models may or may not include stiffeners on the flange of the T-shaped section. These connectors are tested for modelling the section in tension in a beam-column connector bolted with a projected end plate. The thickness of the end plate (flange of the T-shaped section) constitutes the main parameter in this study. Test results highlight the role of the end plate in different possible failure modes. A numerical calculation based on a model taken from the literature permitted comparison with test results. The analysis of results showed some discrepancies. Improvements must be made to the model used to reconcile the theory and the experience, and to adapt it to connectors that are under tension.Key words: bolted assembly, end plate, experimentation, stiffening, modelling.
Polycyclic aromatic hydrocarbon degradation in soil surrounding an outdoor coal storage pile
Authors: Dore Sophia Y , Laursen Andrew E , Kulpa, Jr. Charles F
Published: September 2003

Soil surrounding an outdoor coal storage pile is impacted by highly acidic leachate containing polycyclic aromatic hydrocarbons (PAHs) and heavy metals. Soil samples were taken along transects radiating out from an outdoor coal storage pile and soil microcosms amended with 14C-labelled naphthalene were set up to assess the ability of organisms within this acidic soil to degrade PAHs. In the less acidic transect all soil samples were capable of naphthalene mineralization. In the more acidic transect, samples taken from points further away from the coal pile showed faster mineralization rates than samples taken from points close to the coal pile. Key words: coal pile, acidic soils, PAH degradation, naphthalene mineralization, soil microcosms.
Optimization of liquid state bioconversion process for microbial treatment of domestic wastewater sludge
Authors: Alam Md. Z , Fakhru'l-Razi A , Molla Abul H
Published: September 2003

The evaluation of cheap carbon sources (co-substrate) and process conditions for microbial treatment of domestic wastewater sludge (DWS) was investigated using a liquid state bioconversion (LSB) laboratory scale process. Six cheap carbon sources were used: wheat flour (WF), rice flour (RF), corn flour (CF), sago starch (SS), cassava starch (CS), and commercial sugar (S). Process conditions such as co-substrate(s) concentration, temperature, initial pH, and inoculum size were optimized in terms of dry filter cake (DFC) production, removal of total suspended solids (TSS), turbidity (optical density against distilled water, 660 nm), and chemical oxygen demand (COD) in supernatant. The results obtained indicated that sludge containing wheat flour as a carbon source was a better co-substrate for microbial growth, with significant utilization for minimizing the dissolved and suspended materials in sludge. The optimized parameters for fungal treatment of DWS obtained were 1.52% (w/w) of WF concentration, temperature of 3335°C, initial pH of 4.55.5, and inoculum size of 23% v/w. Effective results for optimum values were recoded at 4 d of microbial treatment.Key words: liquid state bioconversion, domestic wastewater sludge, process conditions, cheap carbon sources, microbial treatment.
Microbial population dynamics in enhanced biological phosphorus removing activated sludge systems
Authors: Cloete Thomas E , Theron Jacques
Published: September 2003

In terms of wastewater treatment, the activated sludge process is probably the most important biotechnological process at present. Although a considerable amount of work has been done on system design and process engineering, some systems designed for enhanced biological phosphorus removal (EBPR) fail, thus necessitating chemical precipitation to meet effluent standards. Studies on the microbial ecology of activated sludge to optimize the process have received much attention. Culture-dependent, fluorescent antibody and molecular techniques, as well as polyacrylamide gel electrophoresis and community-level carbon source utilization methods have contributed to a better, but yet incomplete understanding of EBPR as well as other problems, such as bulking and foaming, which are microorganism related. Hence, microbial diversity and, more importantly, the function of populations in a specific community have not been elucidated, excepting in cases where a specific function can be attributed to a specific microbial population (e.g., nitrification). Most of our current knowledge regarding the microbiology of EBPR has been descriptive. However, as the methodology for studying microbial population dynamics improve, it will lead to a fundamental understanding of EBPR, bulking, foaming, etc., which could lead to major improvements in process design and operation. Key words: enhanced biological phosphorus removal, activated sludge, population dynamics, microenvironments, physicochemical properties, metabolic processes, modeling.
Impact of raw water turbidity fluctuations on drinking water quality in a distribution system
Authors: Gauthier Vincent , Barbeau Benoit , Tremblay Geneviève , Millette Robert , Bernier Anne-Marie
Published: September 2003

Turbidity is a widely used parameter around the world for describing drinking water quality. Sometimes, turbidity at water treatment plant outlets may reach high values during short periods of time, and this is acceptable according to some current drinking water regulations. In this study, the quantity and nature (chemical and microbiological) of suspended matter, which may travel throughout a distribution system (DS) during turbid events  affecting both raw water and water treatment  were evaluated. Treated water included filtration with no coagulant addition. During turbid events, the concentration of suspended particles increased in treated water, and a similar increase (quantity and nature) was observed throughout the DS. Bacterial indicators of contamination (total and fecal coliforms, enteroccocci, spores of Clostridium perfringens) were not found in either treated water nor in the DS during turbid events. Nevertheless, a higher bacterial aerobic spore concentration was associated with turbid events for raw, treated, and distributed water, therefore suggesting the potential passage of pathogens, if present in raw waters. Cultivable bacteria concentrations remained low in treated and distributed water regardless of the turbidity. These results emphasize the need to carefully monitor raw and treated water quality for utilities using "high quality" water resources with limited treatment barriers, especially when such water resources are affected by even slight turbidity variations. Key words: aerobic spore-forming bacteria, distribution system, drinking water, filtration, turbidity, suspended particles, water quality.
The essential role of carotid body chemoreceptors in sleep apnea
Authors: Smith Curtis A , Nakayama Hideaki , Dempsey Jerome A
Published: September 2003

Sleep apnea is attributable, in part, to an unstable ventilatory control system and specifically to a narrowed "CO2 reserve" (i.e., the difference in PaCO2 between eupnea and the apneic threshold). Findings from sleeping animal preparations with denervated carotid chemoreceptors or vascularly isolated, perfused carotid chemoreceptors demonstrate the critical importance of peripheral chemoreceptors to the ventilatory responses to dynamic changes in PaCO2. Specifically, (i) carotid body denervation prevented the apnea and periodic breathing that normally follow transient ventilatory overshoots; (ii) the CO2 reserve for peripheral chemoreceptors was about one half that for brain chemoreceptors; and (iii) hypocapnia isolated to the carotid chemoreceptors caused hypoventilation that persisted over time despite a concomitant, progressive brain respiratory acidosis. Observations in both humans and animals are cited to demonstrate the marked plasticity of the CO2 reserve and, therefore, the propensity for apneas and periodic breathing, in response to changing background ventilatory stimuli.Key words: sleep apnea, carotid bodies, hypocapnia, apneic threshold, periodic breathing.
Mechanism of the negative inotropic effects of α1-adrenoceptor agonists on mouse myocardium
Authors: Varma Daya R , Rindt Hansjorg , Chemtob Sylvain , Mulay Shree
Published: September 2003

This study was done to identify the mechanism of the α1-adrenoceptor (AR) mediated negative inotropic effects of phenylephrine (PE) on adult mouse myocardium. As reported by others, we also found that the nonselective α1AR agonist PE produced a negative inotropic effect on ventricular strips from adult mice that was inhibited by the α1AAR antagonist 5-methylurapidil (5MU) but not by the α1BAR antagonist chloroethylclonidine (CEC) or the α1DAR antagonist BMY 7378. The selective α1AAR agonist A61603 also produced a negative inotropic effect, which was antagonized by 5MU. Phorbol 12,13-dibutyrate (activator of all PKC isoforms) mimicked the negative inotropic responses to PE and A61603. The negative inotropic effects of PE were inhibited by bisindolylmaleimide (inhibitor of all PKC isoforms) but not by Gö 6976 (inhibitor of Ca2+-dependant PKC). Rottlerin, an inhibitor of Ca2+-independent PKCδ, antagonized the negative inotropic effects of PE and A61603. PE and A61603 increased the translocation of PKCδ, which was prevented by rottlerin. These data suggest that the α1AR-mediated negative inotropy on adult mouse myocardium is signaled by Ca2+-independent PKCδ.Key words: phorbol 12,13-dibutyrate, 5-methylurapidil, BMY 7378, chloroethylclolidine, Ca2+-dependant PKC isoforms, α1A-adrenoceptor.
Effects of Pb2+ on the transient outward potassium current in acutely dissociated rat hippocampal neurons
Authors: Yu Kuai , Ge Shao-Yu , Dai Xiao-Qing , Ruan Di-Yun
Published: September 2003

Modulation of the voltage-dependent transient outward potassium current (IA) by Pb2+ was studied in acutely dissociated rat hippocampal pyramidal cells from the CA1 region at postnatal ages 714 days using the conventional whole-cell patch-clamp technique. In the presence of different concentrations of external Pb2+, the initial delay and activation time of IA were concentration-dependently lengthened. In particular, the initial delay was evenlonger in 1 mM Pb2+, showing no signs of saturation. Pb2+ also slowed the inactivation of IA, for decay time constants in the presence of Pb2+ were increased under the same experimental protocols. The activation curves, which were reasonably fitted by a single Boltzmann function, illustrated that Pb2+ increased the voltage threshold of IA and shifted the normalized activation currentvoltage curves to more depolarizing voltage commands. Moreover, Pb2+ significantly affected the steady-state inactivation of IA. The application of Pb2+ made the curves of the steady-state inactivation of IA shift to more depolarizing voltages with little change in the slopes factors. In brief, the results demonstrated that Pb2+ is a dose- and voltage-dependent, reversible blocker of IA currents of hippocampal CA1 neurons. The observations were fitted by the revised "Kuo and Chen type model", which postulates a Pb2+-selective site near the pore of the IA channel and that modulation of the IA channel by Pb2+ is the result of the competitive influences of Pb2+ on opening and inactivating different pathways.Key words: patch clamp, IA, Pb2+, hippocampal neuron, rat.
Effects of barbiturates on human platelet aggregation differ depending on their chemical structures
Authors: Sato Masami , Hirakata Hideo , Ikeda Masahiro , Fukuda Kazuhiko
Published: September 2003

The effects of barbiturates on human platelet function are not fully understood. Since we have already revealed the effects and mechanisms of thiopental, thiamylal, and pentobarbital in platelets, the present study attempted to elucidate (i) the effects of other barbiturates on human platelet aggregation, (ii) the underlying mechanisms, and (iii) the structurefunction relationship of barbiturates in platelets. Barbiturates, including amobarbital, butalbital, secobarbital, barbital, phenobarbital, metharbital, and primidone, were examined. Human platelet aggregation induced by adenosine diphosphate (ADP), epinephrine, and (+)-9,11-epithia-11,12-methano-thromboxane A2(STA2), a thromboxane A2analog, was measured using an 8-channel light-transmission aggregometer. The cytosolic free calcium concentration ([Ca2+]i) was measured by fluorometer using fura-2 loaded platelets. Inositol 1,4,5-trisphosphate (IP3) formation induced by STA2was determined by a commercially available IP3assay kit. Amobarbital, butalbital, and secobarbital suppressed ADP-, epinephrine- and STA2-induced platelet aggregation and the STA2-induced [Ca2+]iincrease, even when Ca2+influx was blocked by Ni2+. However, they did not affect STA2-induced IP3formation. Barbital, phenobarbital, metharbital, and primidone (up to 1 mM) had no effect on ADP- and epinephrine-induced platelet aggregation. Thus, we conclude that amobarbital, butalbital, and secobarbital inhibit platelet aggregation by suppressing [Ca2+]iincrease without affecting IP3formation. However, these antiaggregatory effects may not have clinical importance, since the barbiturate concentrations used were higher than clinically relevant ones. The other tested barbiturates had no effects on platelet aggregation. The data indicate that the effects of barbiturates on platelet aggregation differ depending on their chemical structures.Key words: platelet aggregation, barbiturates, cytosolic calcium concentration, inositol 1,4,5-trisphosphate.
Role of metallothionein in regulating the abundance of histochemically reactive zinc in rat tissues
Authors: Paski Shirley C , Covery Lore , Kummer Angela , Xu Zhaoming
Published: September 2003

The objectives of this study were (i) to investigate the modulating effects of zinc nutrition on histochemically reactive zinc in the rat intestine and liver and (ii) to assess the relationship between histochemically reactive zinc and metallothionein-bound zinc in these tissues under varying zinc nutrition. Male Wistar rats were fed a zinc-deficient (3 mg zinc/kg), adequate-zinc (30 mg zinc/kg, ad libitum or pair-fed), or zinc-supplemented (155 mg zinc/kg) diet for 2 or 6 weeks. Plasma N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide-reactive zinc reflected dietary zinc intake. Abundance of the intestine histochemically reactive zinc was correlated with dietary zinc intake after 2 weeks of dietary treatment. Dietary zinc intake had no effect on the abundance of the intestine histochemically reactive zinc after 6 weeks of dietary treatment and the hepatic histochemically reactive zinc after both 2 and 6 weeks of dietary treatment. This lack of effect of dietary zinc intake on the abundance of histochemically reactive zinc was associated with a higher level of metallothionein. The molecular-mass distribution profile revealed that N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide-reactive zinc and metallothionein-bound zinc represented two different, but interrelated, pools of zinc. Overall, these results suggested that the abundance of histochemically reactive zinc was homeostatically regulated, which was partially achieved through the regulation of metallothionein levels in rats.Key words: N-6-methoxy-para-toluenesulfonamide (TSQ), histochemically reactive zinc, plasma TSQ-reactive zinc, intestine, metallothionein, rats.
Effects of dietary 27-hydroxycholesterol on cholesterol metabolism and bile acid biosynthesis in the hamster
Authors: Souidi Maâmar , Dubrac Sandrine , Parquet Michel , Milliat Fabien , Férézou Jacqueline , Sérougne Colette , Loison Carole , Riottot Michel , Boudem Nawel , Bécue Thierry , Lutton Claude
Published: September 2003

27-hydroxycholesterol (27OH-Chol) is an important endogenous oxysterol resulting from the action of sterol 27-hydroxylase (CYP27A1) on cholesterol in the liver and numerous extrahepatic tissues. It may act as a modulator of cholesterol and bile acid metabolism. The effects of 27OH-Chol on the main enzymes and receptors of cholesterol metabolism were investigated by feeding male hamsters a diet supplemented with 27OH-Chol (0.1% w/w) for 1 week. Intestinal scavenger class B, type I (SR-BI) protein level was decreased (65%), but hepatic expression was increased (+34%). Liver 3β-hydroxy-3β-methyl glutaryl coenzyme A reductase (58%), cholesterol 7α-hydroxylase (54%), oxysterol 7α-hydroxylase (44%), and sterol 12α-hydroxylase (70%) activities were all decreased. Bile acid composition was changed (fourfold increase in the chenodeoxycholic/cholic acid ratio). This study demonstrates that dietary 27OH-Chol modulates major enzymes of cholesterol metabolism and alters the biliary bile acid profile, making it more hydrophobic, at least at this level of intake. Its effects on SR-BI protein levels are organ dependent. The properties of 27OH-Chol or its metabolites on cholesterol metabolism probably result from the activation of specific transcription factors. Key words: cholesterol 7α-hydroxylase (CYP7A1), sterol 12α-hydroxylase (CYP8B1), sterol 27-hydroxylase (CYP27A1), 3β-hydroxy-3β-methyl glutaryl coenzyme A reductase (HMGCoAR), scavenger receptor class B type I (SR-BI).
Stress-induced fever after postischemic rectal temperature measurements in the gerbil
Authors: Clark Darren L , DeBow Suzanne B , Iseke Melanie D , Colbourne Frederick
Published: September 2003

Postischemic temperature, which modulates brain injury, is commonly determined via a rectal temperature (Trec) probe. This procedure causes a stress-induced fever (SIF) in rodents that may aggravate injury or diminish the efficacy of a neuroprotectant. We continually measured core temperature (Tcore) via an implanted telemetry probe and made 16 Trec measurements over 4 days in sham and ischemic gerbils (5 min bilateral carotid artery occlusion). Controls did not have Trec sampled, but Tcore was measured. Rectal temperature measurements predicted Tcore in sham and ischemic gerbils. The Trec measurements caused a SIF (1°C peak) in shams that did not habituate, whereas the SIF was initially absent and then increased over days in ischemic gerbils. Ischemic groups had similar CA1 injury (~32% remaining), presumably because Trec measurements only resulted in a significant SIF starting on day 2 postischemia, when cell death is less sensitive to hyperthermia. Caution is warranted with Trec measurements, since the resultant SIF occurs to different extents in normal and ischemic rodents. Furthermore, the SIF could vary according to many other factors, such as the type and severity of insult, the time and frequency of measurement, and drug treatment. Accordingly, postischemic Trec measurements should be replaced with telemetry probes.Key words: ischemia, stress-induced fever, hyperthermia, gerbil, rectal temperature.
Taurine depletion alters vascular reactivity in rats
Authors: Abebe Worku , Mozaffari Mahmood S
Published: September 2003

We recently showed that chronic taurine supplementation is associated with attenuation of contractile responses of rat aorta to norepinephrine and potassium chloride. However, the potential involvement of endogenous taurine in modulation of vascular reactivity is not known. Therefore, we examined the effect of β-alanine-induced taurine depletion on the in vitro reactivity of rat aorta to selected vasoactive agents. The data indicate that both norepinephrine- and potassium-chloride-induced maximum contractile responses of endothelium-denuded aortae were enhanced in taurine-depleted rats compared with control animals. However, taurine depletion did not affect tissue sensitivity to either norepinephrine or potassium chloride. By contrast, sensitivity of the endothelium-denuded aortae to sodium nitroprusside was attenuated by taurine depletion. Similarly, taurine deficiency reduced the relaxant responses of endothelium-intact aortic rings elicited by submaximal concentrations of acetylcholine, and this effect was associated with decreased nitric oxide production. Taken together, the data suggest that taurine depletion augments contractility but attenuates relaxation of vascular smooth muscle in a nonspecific manner. Impairment of endothelium-dependent responses, which is at least in part associated with reduced nitric oxide generation, may contribute to the attenuation of the vasorelaxant responses. These vascular alterations could be of potential consequence in pathological conditions associated with taurine deficiency.Key words: rat aorta, β-alanine, taurine depletion, vascular reactivity.
Breeding ecology of Horned Puffins (Fratercula corniculata) in Alaska: annual variation and effects of El Niño
Authors: Harding A MA , Piatt J F , Hamer K C
Published: September 2003

Both within and among seabird species, different aspects of breeding biology may respond to changes in prey availability in distinct ways, and the identification of species-specific breeding parameters that are sensitive to food availability is useful for monitoring purposes. We present data from a 5-year study (19951999) of the breeding ecology of Horned Puffins (Fratercula corniculata) in Alaska. The El Niño  Southern Oscillation event of 19971998 provided an opportunity to examine the sensitivity of various breeding parameters to a reduction in prey availability caused by the anomalous oceanographic conditions of 1998. Horned Puffins were able to maintain high fledging success (8397%) over the 5 years of the study, despite the poor local feeding conditions in 1998. The rate of increase in chick mass was lowest in 1998, and evidence suggests that chicks also fledged at the youngest ages in that year. The impacts of reduced food availability on growth varied among body structures, suggesting differential allocation of energy and nutrients. There was no variation among years in either chick diet or the mass of food loads delivered by adults. We suggest that rates of chick growth, specifically mass increase, may be a good parameter to measure for use in monitoring Horned Puffins.
New information on the eggshell of ratites (Aves) and its phylogenetic implications
Authors: Zelenitsky Darla K , Modesto Sean P
Published: September 2003

A reappraisal of the eggshell of ratites clarifies aspects of its microstructure and ultrastructure. The phylogenetic usefulness of the eggshell data, consisting of discrete characters, is assessed using eggshell characters alone and by adding the eggshell characters to a data matrix from the literature based on skeletal characters. The resultant tree from the eggshell data alone yields Apteryx as the most basal ratite, dinornithids as the sister taxon of a clade of large living ratites, with Casuarius and Dromaius in a sister-group relationship. The combined eggshell and skeletal analysis revealed most groupings within Ratitae that were based on previous cladistic analysis of the skeletal characters alone, but also supports two equally parsimonious topologies: one identifies Dinornithidae and Apteryx as a clade at the base of Ratitae, and the other identifies Apteryx as the sister taxon of a clade consisting of all the other ratites. It is determined that the characteristics used to define the improperly named "ratite morphotype" in the current eggshell parataxonomy are not synapomorphies of the eggshell of Ratitae. An expanded cladistic analysis of the eggshells of avian and non-avian theropods is required to determine the phylogenetic usefulness of the characteristics of the ratite morphotype.
Risk factors affecting escape behavior by the desert iguana, Dipsosaurus dorsalis: speed and directness of predator approach, degree of cover, direction of turning by a predator, and temperature
Authors: Cooper Jr. W E
Published: September 2003

Escape from predators by desert iguanas (Dipsosaurus dorsalis) conforms to predictions of optimal escape theory based on risk. I simulated an approaching predator to study risk factors. The primary response variable was approach distance (= flight-initiation distance), i.e., the distance between predator and prey when the prey initiates escape. In additional studies, I recorded whether lizards permitted me to approach close enough to noose them (an indicator of wariness) and the method of escape. Approach distance was greater when the predator approached rapidly than slowly and directly than indirectly, and when the predator turned toward the lizard rather than away. It was greater in open than in more densely covered habitats, which may reflect greater risk due to conspicuousness and (or) a greater distance to refuge. Early in the day at lower air temperatures, desert iguanas permitted a closer approach before initiating escape. While basking after emergence from burrows, lizards escaped into burrows; later in the day they fled. Lizards that fled had high body temperatures; a single individual captured immediately after entering a burrow had a lower body temperature. Lizards presumably enter burrows when low body temperature limits the running speed, but burrow use is costly because attainment of the activity temperature is delayed because of time elapsed and the temperature decrease in burrows.
Population age structure and growth in four syntopic amphibian species inhabiting a large river floodplain
Authors: Cogalniceanu Dan , Miaud Claude
Published: September 2003

River floodplains are disturbance-dominated landscapes where floods are major regulators of both aquatic and nearby terrestrial communities. Amphibians are common inhabitants of floodplains and their life cycle depends on both aquatic and terrestrial habitats. We focused on how different syntopic species of amphibians reacted to the environmental conditions of a large river floodplain. We examined life-history traits such as population age structure and growth in small- and large-bodied species of anurans and urodeles in the lower Danube River floodplain in Romania. Two newt species, Triturus vulgaris (small-bodied) and Triturus dobrogicus (large-bodied), and two anuran taxa, Bombina bombina (small-bodied) and the Rana esculenta complex (large-bodied), were included in the study. The ages of individuals estimated by skeletochronology varied from 3 to 56 years for T. vulgaris and from 23 to 45 years for T. dobrogicus. In the anurans, ages varied from 2 to 5 years in B. bombina and from 4 to 10 years in the R. esculenta complex. The numbers of breeding opportunities (i.e., the number of years the adults reproduce) are similar in both newt species (3), while growth rates and age at maturity differ between the large- and small-bodied species. In anurans, the number of breeding opportunities for the smallest species, B. bombina (4), is associated with a high growth rate and earlier maturation. In the larger R. esculenta complex, the higher number of breeding opportunities (7) is associated with a low growth rate and delayed maturation. The study of age distribution and associated parameters provides useful information on population life history. We discuss how age structure and growth of amphibian populations in large river floodplains can be used as indicators of environmental conditions.
Effect of food availability on reproduction and brood size in a freshwater brooding bivalve
Authors: Beekey Mark A , Karlson Ronald H
Published: September 2003

Brood size is often constrained by the amount of energy available to produce offspring. Yet, energetic constraints may not be as important if the physical capacity to brood offspring is limited. Investigating the relative importance of energetic and physical constraints on brood size is necessary to understand how reproductive strategies are molded by natural selection. We investigated how food availability affects brood size in Sphaerium striatinum, a freshwater bivalve. We reared juveniles to adulthood under three food levels in a common garden experiment. The number of reproductive attempts, brood size, and stage of offspring development were measured. Clams reared with the most food reproduced more often, produced more offspring per reproductive attempt, and contained larger broods than clams reared with less food. These data support the notion that food availability is an important factor in the production of offspring and overall brood size. However, the number of offspring surviving to later stages of development was not different among treatments. In fact, clams reared with the most food lost proportionately more offspring than clams reared with less food. We conclude that physical constraints are more important in determining overall brood size than energetic constraints in S. striatinum.
Winter habitat use by female caribou in relation to wildland fires in interior Alaska
Authors: Joly Kyle , Dale Bruce W , Collins William B , Adams Layne G
Published: September 2003

The role of wildland fire in the winter habitat use of caribou (Rangifer tarandus) has long been debated. Fire has been viewed as detrimental to caribou because it destroys the slow-growing climax forage lichens that caribou utilize in winter. Other researchers argued that caribou were not reliant on lichens and that fire may be beneficial, even in the short term. We evaluated the distribution of caribou relative to recent fires (<50 years old) within the current winter range of the Nelchina caribou herd in east-central Alaska. To address issues concerning independence and spatial and temporal scales, we used both conventional very high frequency and global positioning system telemetry to estimate caribou use relative to recent, known-aged burns. In addition, we used two methods to estimate availability of different habitat classes. Caribou used recently burned areas much less than expected, regardless of methodologies used. Moreover, within burns, caribou were more likely to use habitat within 500 m of the burn perimeter than core areas. Methods for determining use and availability did not have large influences on our measures of habitat selectivity.
The influence of Monocystis sp. infection on growth and mating behaviour of the earthworm Lumbricus terrestris
Authors: Field Stuart G , Schirp Hendrik J , Michiels Nicolaas K
Published: September 2003

Parasites are capable of behavioural manipulation of their hosts in an effort to complete their life cycle and thus increase their fitness at a cost to the host. Hosts are therefore expected to exhibit mate choice decisions that serve to minimize either their own infection risk or that of their offspring using biological cues as criteria. Skin colour could be one such cue. Lumbricus terrestris is heavily parasitized by the protozoan Monocystis sp.; although infection levels can be highly variable, field samples containing 100% infected individuals are common. We observed earthworms, in pairs, for 4 weeks and recorded growth, copulation number, skin colour, and parasite load. The following predictions were made: (i) growth and copulation frequency should decrease with parasite load and (ii) parasite load correlates with skin colour. Contrary to our expectation, neither growth rate nor copulation number correlated with parasite load, yet skin colour did correlate significantly with parasite load. Mature and subadult individuals were also found to differ significantly in degree of infection. These findings suggest a parasite with a low short-term fitness effect on its host.
Long-term evaluation of pup growth and preweaning survival rates in subantarctic fur seals,Arctocephalus tropicalis, on Amsterdam Island
Authors: Chambellant Magaly , Beauplet Gwénaël , Guinet Christophe , Georges Jean-Yves
Published: September 2003

This study is the first to investigate pup preweaning growth and survival rates over seven consecutive breeding seasons in subantarctic fur seals, Arctocephalus tropicalis, on Amsterdam Island, southern Indian Ocean. Growth and survival were studied in relation to year and pup sex, birth date, birth mass, and growth rate at 60 days of age. The pup growth rate decreased over the 7-year study period and was the lowest ever found in otariids, which suggests that lactating females experience constant low food availability. Male and female pups grew and survived at similar rates. Pups that were heavier at birth grew faster and exhibited better early survival (i.e., the first 2 months of life) than pups that were lighter at birth. However, no such relationship was detected for late survival (i.e., from 2 months to weaning) in this long-lactating species. No relationship was found between pup growth rate, pup survival rate, and sea-surface temperature (SST) gradient during the study period, especially during the later years of good trophic conditions (i.e., a high SST gradient). Such dissociations suggest that variation in food availability may not be the only factor influencing pup performance until weaning. We therefore propose that the subantarctic fur seal population is reaching its carrying capacity and that a density-dependent effect is occurring on Amsterdam Island.
Spatiotemporal heterogeneity in recruitment of larval parasites to shore crab intermediate hosts: the influence of shorebird definitive hosts
Authors: Latham A David M. , Poulin Robert
Published: September 2003

Parasitism is a major biotic determinant of animal population dynamics and community structure. Temporal and spatial heterogeneity in parasitism is commonly observed in intermediate host populations. Understanding the causes of temporal and spatial variation in the recruitment of parasites is crucial if we are to manage host populations and animal communities effectively. Here, the temporal and spatial dynamics of Profilicollis antarcticus and Profilicollis novaezelandensis (Acanthocephala) infections in three species of shore crabs (Macrophthalmus hirtipes, Hemigrapsus edwardsii, and Hemigrapsus crenulatus) are examined in relation to the distribution and abundance of shorebird definitive hosts. Temporal patterns of infection were observed in M. hirtipes but not the other two species. Spatial heterogeneity in recruitment of acanthocephalan larvae to M. hirtipes and H. edwardsii populations was found both within and between locations. Weak evidence is found that infection levels in crab populations are related to the distribution and abundance of shorebird hosts both temporally and spatially. In this system, abiotic factors seem to be at least as important in determining how infection levels vary in time and space as the input of parasite eggs from bird definitive hosts.
The L-G Phase Transition and the Nucleon–Nucleon Interaction Potential within QHD-I Model
Authors: Meng Jin , Li Jiarong , Chen Jisheng
Published: September 2003

The nucleon–nucleon interaction potential in hot/dense nuclear matter is studied within the QHD-I model. We find that a Yukawa potential, which contains attractive and repulsive terms, acting between nucleons is modified by the variation of the Debye mass. In particular, a nucleon system described by this Yukawa potential will be unbound at some critical T and μ. The critical point is very close to that of the L-G phase transition given in the literatures.
Abelian Projection of Massive SU(2) Yang–Mills Theory
Authors: Deguchi Shinichi , Kokubo Yousuke
Published: September 2003

We derive an effective Abelian gauge theory (EAGT) of a modified SU(2) Yang–Mills theory. The modification is made by explicitly introducing mass terms of the off-diagonal gluon fields into pure SU(2) Yang–Mills theory, in order that Abelian dominance at a long-distance scale is realized in the modified theory. In deriving the EAGT, the off-diagonal gluon fields involving longitudinal modes are treated as fields that produce quantum effects on the diagonal gluon field and other fields relevant at a long-distance scale. Unlike earlier papers, a necessary gauge fixing is carried out without spoiling the global SU(2) gauge symmetry. We show that the EAGT allows a composite of the Yukawa and the linear potentials which also occurs in an extended dual Abelian Higgs model. This composite potential is understood to be a static potential between color-electric charges. In addition, we point out that the EAGT involves the Skyrme–Faddeev model.
Distribution of special sequences moduloa large prime
Authors: Garaev M. Z. , Kueh Ka-Lam
Published: September 2003

We study the sets {gx − gy(mod p) : 1 ≤ x, y ≤ N} and {xy : 1 ≤ x, y ≤ N} where p is a large
prime number, g is a primitive root, and p2/3 < N < p.
The additive approximation on a four‐variate Jensen‐type operator equation
Authors: Wang Jian
Published: September 2003

We study the Hyers‐Ulam stability theory of a four‐variate
Jensen‐type functional equation by considering the approximate
remainder ϕ and obtain the corresponding error formulas. We
bring to light the close relation between the β‐homogeneity
of the norm on F∗‐spaces and the approximate remainder ϕ,
where we allow p, q, r, and s to be different in their
Hyers‐Ulam‐Rassias stability.
Life and Perceptual Intentionality
Authors: Barbaras Renaud
Published: September 2003

Husserl is the first philosopher who has managed to account for the specificity of perception, characterized as givenness by sketches (Abschattungen); but neither Husserl nor Merleau-Ponty have given a satisfying definition of the subject of perception. This article tries to show that the subject of perception must be conceived as living being and that, therefore, the phenomenology of perception must lead to a phenomenology of life. Here, life is approached from an existential point of view, that is to say, as a specific relationship to the world. However, life cannot be characterized from human existence in a privative way, as in Heidegger's philosophy: on the contrary, human existence, and particularly perception itself, must be understood from vital existence, and accordingly, an "additive" anthropology must replace the privative zoology. The hypothesis of this article is that it is by characterizing life as desire, we are able to account for perception as givenness by sketches.
Prescription Stimulant Use During Pregnancy and Risk of Neurodevelopmental Disorders in Children
Authors: Suarez Elizabeth A. , Bateman Brian T. , Hernandez-Diaz Sonia , Straub Loreen , McDougle Christopher J. , Wisner Katherine L. , Gray Kathryn J. , Pennell Page B. , Lester Barry , Zhu Yanmin , Mogun Helen , Huybrechts Krista F.
Published: January 2024

Importance

Use of medications for attention-deficit/hyperactivity disorder (ADHD) during pregnancy is increasing in the US. Whether exposure to these medications in utero impacts the risk of neurodevelopmental disorders in children is uncertain.

Objective

To evaluate the association of childhood neurodevelopmental disorders with in utero exposure to stimulant medications for ADHD.

Design, Setting, and Participants

This cohort study included health care utilization data from publicly insured (Medicaid data from 2000 to 2018) and commercially insured (MarketScan Commercial Claims Database data from 2003 to 2020) pregnant individuals aged 12 to 55 years in the US with enrollment from 3 months prior to pregnancy through 1 month after delivery, linked to children. Children were monitored from birth until outcome diagnosis, disenrollment, death, or end of the study (December 2018 for Medicaid and December 2020 for MarketScan).

Exposures

Dispensing of amphetamine/dextroamphetamine or methylphenidate in the second half of pregnancy.

Main Outcomes and Measures

Autism spectrum disorder, ADHD, and a composite of any neurodevelopmental disorder were defined using validated algorithms. Hazard ratios were estimated comparing amphetamine/dextroamphetamine and methylphenidate to no exposure.

Results

The publicly insured cohort included 2 496 771 stimulant-unexposed, 4693 amphetamine/dextroamphetamine-exposed, and 786 methylphenidate-exposed pregnancies with a mean (SD) age of 25.2 (6.0) years. The commercially insured cohort included 1 773 501 stimulant-unexposed, 2372 amphetamine/dextroamphetamine-exposed, and 337 methylphenidate-exposed pregnancies with a mean (SD) age of 31.6 (4.6) years. In unadjusted analyses, amphetamine/dextroamphetamine and methylphenidate exposure were associated with a 2- to 3-fold increased risk of the neurodevelopmental outcomes considered. After adjustment for measured confounders, amphetamine/dextroamphetamine exposure was not associated with any outcome (autism spectrum disorder: hazard ratio [HR], 0.80; 95% CI, 0.56-1.14]; ADHD: HR, 1.07; 95% CI, 0.89-1.28; any neurodevelopmental disorder: HR, 0.91; 95% CI, 0.81-1.28). Methylphenidate exposure was associated with an increased risk of ADHD (HR, 1.43; 95% CI, 1.12-1.82]) but not other outcomes after adjustment (autism spectrum disorder: HR, 1.06; 95% CI, 0.62-1.81; any neurodevelopmental disorder: HR, 1.15; 95% CI, 0.97-1.36). The association between methylphenidate and ADHD did not persist in sensitivity analyses with stricter control for confounding by maternal ADHD.

Conclusions and Relevance

The findings in this study suggest that amphetamine/dextroamphetamine and methylphenidate exposure in utero are not likely to meaningfully increase the risk of childhood neurodevelopmental disorders.
Gross failure rates and failure modes for a commercial AI‐based auto‐segmentation algorithm in head and neck cancer patients
Authors: Temple Simon W. P. , Rowbottom Carl G.
Published: January 2024

Purpose

Artificial intelligence (AI) based commercial software can be used to automatically delineate organs at risk (OAR), with potential for efficiency savings in the radiotherapy treatment planning pathway, and reduction of inter‐ and intra‐observer variability. There has been little research investigating gross failure rates and failure modes of such systems.

Method

50 head and neck (H&N) patient data sets with “gold standard” contours were compared to AI‐generated contours to produce expected mean and standard deviation values for the Dice Similarity Coefficient (DSC), for four common H&N OARs (brainstem, mandible, left and right parotid). An AI‐based commercial system was applied to 500 H&N patients. AI‐generated contours were compared to manual contours, outlined by an expert human, and a gross failure was set at three standard deviations below the expected mean DSC. Failures were inspected to assess reason for failure of the AI‐based system with failures relating to suboptimal manual contouring censored. True failures were classified into 4 sub‐types (setup position, anatomy, image artefacts and unknown).

Results

There were 24 true failures of the AI‐based commercial software, a gross failure rate of 1.2%. Fifteen failures were due to patient anatomy, four were due to dental image artefacts, three were due to patient position and two were unknown. True failure rates by OAR were 0.4% (brainstem), 2.2% (mandible), 1.4% (left parotid) and 0.8% (right parotid).

Conclusion

True failures of the AI‐based system were predominantly associated with a non‐standard element within the CT scan. It is likely that these non‐standard elements were the reason for the gross failure, and suggests that patient datasets used to train the AI model did not contain sufficient heterogeneity of data. Regardless of the reasons for failure, the true failure rate for the AI‐based system in the H&N region for the OARs investigated was low (∼1%).
Tau maturation in the clinicopathological spectrum of Lewy body and Alzheimer's disease
Authors: Arezoumandan Sanaz , Cousins Katheryn A.Q. , Ohm Daniel T. , Lowe MaKayla , Chen Min , Gee James , Phillips Jeffrey S. , McMillan Corey T. , Luk Kelvin C. , Deik Andres , Spindler Meredith A. , Tropea Thomas F. , Weintraub Daniel , Wolk David A. , Grossman Murray , Lee Virginia , Chen‐Plotkin Alice S. , Lee Edward B. , Irwin David J.
Published: January 2024

Objective

Alzheimer's disease neuropathologic change and alpha‐synucleinopathy commonly co‐exist and contribute to the clinical heterogeneity of dementia. Here, we examined tau epitopes marking various stages of tangle maturation to test the hypotheses that tau maturation is more strongly associated with beta‐amyloid compared to alpha‐synuclein, and within the context of mixed pathology, mature tau is linked to Alzheimer's disease clinical phenotype and negatively associated with Lewy body dementia.

Methods

We used digital histology to measure percent area‐occupied by pathology in cortical regions among individuals with pure Alzheimer's disease neuropathologic change, pure alpha‐synucleinopathy, and a co‐pathology group with both Alzheimer's and alpha‐synuclein pathologic diagnoses. Multiple tau monoclonal antibodies were used to detect early (AT8, MC1) and mature (TauC3) epitopes of tangle progression. We used linear/logistic regression to compare groups and test the association between pathologies and clinical features.

Results

There were lower levels of tau pathology (β = 1.86–2.96, p < 0.001) across all tau antibodies in the co‐pathology group compared to the pure Alzheimer's pathology group. Among individuals with alpha‐synucleinopathy, higher alpha‐synuclein was associated with greater early tau (AT8 β = 1.37, p < 0.001; MC1 β = 1.2, p < 0.001) but not mature tau (TauC3 p = 0.18), whereas mature tau was associated with beta‐amyloid (β = 0.21, p = 0.01). Finally, lower tau, particularly TauC3 pathology, was associated with lower frequency of both core clinical features and categorical clinical diagnosis of dementia with Lewy bodies.

Interpretation

Mature tau may be more closely related to beta‐amyloidosis than alpha‐synucleinopathy, and pathophysiological processes of tangle maturation may influence the clinical features of dementia in mixed Lewy‐Alzheimer's pathology.