bluuebunny/crossref_metadata_2025_split huggingface dataset:
The thermogenesis of digestion in rattlesnakes
Authors: Tattersall Glenn J. , Milsom William K. , Abe Augusto S. , Brito Simone P. , Andrade Denis V. 
Published: January 2004

SUMMARYSome snakes have a feeding regime characterized by the infrequent ingestion of relatively large meals, causing impressive increments in post-prandial metabolism. Metabolism remains elevated for many days, while digestion proceeds, resulting in considerable investment of time and energy. Snakes actively adjust thermoregulatory behavior to raise their body temperature during digestion, exhibiting a post-prandial thermophilic response that accelerates digestion at the expense of higher metabolic rates. In the present study, we investigated the possibility that endogenously derived heat,originating as a byproduct of the post-prandial increase in metabolism, could itself contribute to the elevated body temperature during digestion in the South American rattlesnake Crotalus durissus. We assessed heat production, at a constant environmental temperature, by taking infrared (IR)images of snakes during fasting and after being fed meals varying from 10% to 50% of their own body masses. Our results show clearly that digesting rattlesnakes have significantly increased body temperatures, even when precluded from adjusting their thermoregulatory behavior. The feeding-derived thermogenesis caused the surface body temperature of rattlesnakes to increase by 0.9–1.2°C, a temperature change that will significantly affect digestive performance. The alterations in body temperature following feeding correlated closely with the temporal profile of changes in post-prandial metabolism. Moreover, the magnitude of the thermogenesis was greater for snakes fed large meals, as was the corresponding metabolic response. Since IR imaging only assesses surface temperatures, the magnitude of the thermogenesis and the changes in deep core temperature could be even more pronounced than is reported here.
Effects of temperature and anoxia upon the performance ofin situperfused trout hearts
Authors: Overgaard Johannes , Stecyk Jonathan A. W. , Gesser Hans , Wang Tobias , Farrell Anthony P. 
Published: January 2004

SUMMARYRainbow trout (Oncorhynchus mykiss) are likely to experience acute changes in both temperature and oxygen availability and, like many other organisms, exhibit behavioural selection of low temperatures during hypoxia that acts to reduce metabolism and alleviate the demands on the heart. To investigate whether low temperature protects cardiac performance during anoxia, we studied the effects of an acute temperature change, from 10°C to either 5°C, 15°C or 18°C, upon the performance of in situ perfused trout hearts before, during and after exposure to 20 min of anoxia. Routine cardiac workload mimicked in vivo conditions at the given temperatures, and the effects of anoxia were evaluated as maximal cardiac performance before and after 20 min of anoxic perfusion. Functional data were related to maximal activities of glycolytic enzymes and energetic status of the heart at the termination of the experiment.At high oxygenation, maximum cardiac output and power output increased with temperature (Q10 values of 1.8 and 2.1, respectively) as a result of increased heart rate. Hypoxia tolerance was inversely related to temperature. At 5°C, the hearts maintained routine cardiac output throughout the 20 min period of anoxia, and maximal cardiac performance was fully restored following reoxygenation. By contrast, cardiac function failed sooner during anoxia as temperature was increased and maximal performance after reoxygenation was reduced by 25%, 35% and 55% at 10°C, 15°C and 18°C, respectively. Increased functional impairment following anoxic exposure at elevated temperature occurred even though both cardiac glycolytic enzyme activity and the rate of lactate production were increased proportionally with cardiac work. Nonetheless, there was no indication of myocardial necrosis, as biochemical and energetic parameters were generally unaffected by anoxia.
Maternal effects of egg size on emuDromaius novaehollandiaeegg composition and hatchling phenotype
Authors: Dzialowski Edward M. , Sotherland Paul R. 
Published: January 2004

SUMMARYParental investment in eggs and, consequently, in offspring can profoundly influence the phenotype, survival and ultimately evolutionary fitness of an organism. Avian eggs are excellent model systems to examine maternal allocation of energy translated through egg size variation. We used the natural range in emu Dromaius novaehollandiae egg size, from 400 g to&gt;700 g, to examine the influence of maternal investment in eggs on the morphology and physiology of hatchlings. Female emus provisioned larger eggs with a greater absolute amount of energy, nutrients and water in the yolk and albumen. Variation in maternal investment was reflected in differences in hatchling size, which increased isometrically with egg size. Egg size also influenced the physiology of developing emu embryos, such that late-term embryonic metabolic rate was positively correlated with egg size and embryos developing in larger eggs consumed more yolk during development. Large eggs produced hatchlings that were both heavier (yolk-free wet and dry mass) and structurally larger (tibiotarsus and culmen lengths) than hatchlings emerging from smaller eggs. As with many other precocial birds, larger hatchlings also contained more water, which was reflected in a greater blood volume. However,blood osmolality, hemoglobin content and hematocrit did not vary with hatchling mass. Emu maternal investment in offspring, measured by egg size and composition, is significantly correlated with the morphology and physiology of hatchlings and, in turn, may influence the success of these organisms during the first days of the juvenile stage.
Mechanical work and muscular efficiency in walking children
Authors: Schepens B. , Bastien G. J. , Heglund N. C. , Willems P. A. 
Published: January 2004

SUMMARYThe effect of age and body size on the total mechanical work done during walking is studied in children of 3–12 years of age and in adults. The total mechanical work per stride (Wtot) is measured as the sum of the external work, Wext (i.e. the work required to move the centre of mass of the body relative to the surroundings), and the internal work, Wint (i.e. the work required to move the limbs relative to the centre of mass of the body, Wint,k,and the work done by one leg against the other during the double contact period, Wint,dc). Above 0.5 m s–1, both Wext and Wint,k, normalised to body mass and per unit distance (J kg–1 m–1), are greater in children than in adults; these differences are greater the higher the speed and the younger the subject. Both in children and in adults, the normalised Wint,dc shows an inverted U-shape curve as a function of speed, attaining a maximum value independent of age but occurring at higher speeds in older subjects. A higher metabolic energy input (J kg–1 m–1) is also observed in children,although in children younger than 6 years of age, the normalised mechanical work increases relatively less than the normalised energy cost of locomotion. This suggests that young children have a lower efficiency of positive muscular work production than adults during walking. Differences in normalised mechanical work, energy cost and efficiency between children and adults disappear after the age of 10.
Moments and power generated by the horse (Equus caballus) hind limb during jumping
Authors: Dutto Darren J. , Hoyt Donald F. , Clayton Hilary M. , Cogger Edward A. , Wickler Steven J. 
Published: January 2004

SUMMARYThe ability to jump over an obstacle depends upon the generation of work across the joints of the propelling limb(s). The total work generated by one hind limb of a horse and the contribution to the total work by four joints of the hind limb were determined for a jump. It was hypothesized that the hip and ankle joints would have extensor moments performing positive work, while the knee would have a flexor moment and perform negative work during the jump. Ground reaction forces and sagittal plane kinematics were simultaneously recorded during each jumping trial. Joint moment, power and work were determined for the metatarsophalangeal (MP), tarsal (ankle), tibiofemoral(knee) and coxofemoral (hip) joints. The hip, knee and ankle all flexed and then extended and the MP extended and then flexed during ground contact. Consistent with our hypothesis, large extensor moments were observed at the hip and ankle joints and large flexor moments at the knee and MP joints throughout ground contact of the hind limb. Peak moments tended to occur earlier in stance in the proximal joints but peak power generation of the hind limb joints occurred at similar times except for the MP joint, with the hip and ankle peaking first followed by the MP joint. During the first portion of ground contact (≈40%), the net result of the joint powers was the absorption of power. During the remainder of the contact period, the hind limb generated power. This pattern of power absorption followed by power generation paralleled the power profiles of the hip, ankle and MP joints. The total work performed by one hind limb was 0.71 J kg-1. Surprisingly, the knee produced 85% of the work (0.60 J kg-1) done by the hind limb, and the positive work performed by the knee occurred during the first 40% of the take-off. There is little net work generated by the other three joints over the entire take-off. Velocity of the tuber coxae (a landmark on the pelvis of the animal) was negative (downward) during the first 40% of stance, which perhaps reflects the negative work performed to decrease the potential energy during the first 40% of contact. During the final 60% of contact, the hip,ankle and MP joints generate positive work, which is reflected in the increase of the animal's potential energy.
Dynamical analysis reveals individuality of locomotion in goldfish
Authors: Neumeister H. , Cellucci C. J. , Rapp P. E. , Korn H. , Faber D. S. 
Published: January 2004

SUMMARYGoldfish swimming was analysed quantitatively to determine if it exhibits distinctive individual spatio-temporal patterns. Due to the inherent variability in fish locomotion, this hypothesis was tested using five nonlinear measures, complemented by mean velocity. A library was constructed of 75 trajectories, each of 5 min duration, acquired from five fish swimming in a constant and relatively homogeneous environment. Three nonlinear measures, the `characteristic fractal dimension' and `Richardson dimension',both quantifying the degree to which a trajectory departs from a straight line, and `relative dispersion', characterizing the variance as a function of the duration, have coefficients of variation less than 7%, in contrast to mean velocity (30%). A discriminant analysis, or classification system, based on all six measures revealed that trajectories are indeed highly individualistic,with the probability that any two trajectories generated from different fish are equivalent being less than 1%. That is, the combination of these measures allows a given trajectory to be assigned to its source with a high degree of confidence. The Richardson dimension and the `Hurst exponent', which quantifies persistence, were the most effective measures.
The dichotomous oxyregulatory behaviour of the planktonic crustaceanDaphnia magna
Authors: Pirow R. , Buchen I. 
Published: January 2004

SUMMARYThe dual function of appendage movement (food acquisition, ventilation)proved to be the key to explaining the peculiar oxyregulatory repertoire of the planktonic filter feeder Daphnia magna. Short-term hypoxic exposure experiments with normoxia-acclimated animals under varying food concentrations revealed a dichotomous response pattern with a compensatory tachycardia under food-free conditions and a ventilatory compensation prevailing under food-rich conditions. Food-free, normoxic conditions resulted in maximum appendage beating rates (fa) and half-maximum heart rates (fh), which restricted the scope for oxyregulation to the circulatory system. Food-rich conditions (105algal cells ml-1), on the contrary, had a depressing effect on fa whereas fh increased to 83% of the maximum. In this physiological state, D. magna was able to respond to progressive hypoxia with a compensatory increase in ventilation. A conceptual and mathematical model was developed to analyse the efficiency of ventilatory and circulatory adjustments in improving oxygen transport to tissue. Model predictions showed that an increase in perfusion rate was most effective under both food-free and food-rich conditions in reducing the critical ambient oxygen tension (PO2crit) at which oxygen supply to the tissue started to become impeded. By contrast, a hypothetical increase in ventilation rate had almost no effect on PO2crit under food-free conditions, indicating that appendage movement is driven by nutritive rather than respiratory requirements. However, the model predicted a moderate reduction of PO2crit by hyperventilation under food-rich conditions. Since the regulatory scope for an adjustment in fh was found to be limited in D. magna under these conditions, the increase in ventilation rate is the means of choice for a fed animal to cope with short-term, moderate reductions in ambient oxygen availability. Under long-term and more severe hypoxic conditions, however, the increase in the concentration and oxygen affinity of haemoglobin represents the one and only measure for improving the transport of oxygen from environment to cells.
Glucose dehydrogenase is required for normal sperm storage and utilization in femaleDrosophila melanogaster
Authors: Iida Kaori , Cavener Douglas R. 
Published: January 2004

SUMMARYFemale sperm storage is a key factor for reproductive success in a variety of organisms, including Drosophila melanogaster. The spermathecae,one of the Drosophila sperm storage organs, has been suggested as a long-term storage organ because its secreted substances may enhance the quality of sperm storage. Glucose dehydrogenase (GLD) is widely expressed and secreted in the spermathecal ducts among species of the genus Drosophila. This highly conserved expression pattern suggests that this enzyme might have an important role in female fertility. Here, we examine the function of GLD in sperm storage and utilization using Gld-null mutant females. The absence of GLD reduced the amount of sperm stored in the spermathecae and led to a highly asymmetrical sperm distribution in the two spermathecal capsules of the mutant females. The storage defect was especially severe when the mutant females were crossed to a Gld-mutant male that had previously mated a few hours before the experimental cross. Under this mating condition, the mutant females stored in the spermathecae only one-third of the sperm amount of the wild-type control females. In addition, the mutant females used stored sperm at a slower rate over a longer period compared with wild-type females. Thus, our results indicate that GLD facilitates both sperm uptake and release through the spermathecal ducts.
A compressible flow theory for regenerative compressors with aerofoil blades
Authors: Song J W , Raheel M , Engeda A 
Published: January 2004

Regenerative flow compressors (RFCs) are rotodynamic machines capable of producing high heads at very low flowrates. They have very low specific speed and share some of the characteristics of positive displacement machines such as a roots blower, but without the problems of lubrication and wear. They can produce heads equivalent to that of several centrifugal stages from a single rotor with comparable tip speed. The compression process is usually not regarded as efficient. Typically they produce efficiency of less than 50 per cent but still they have found many applications because they allow the use of fluid dynamic compressors in place of positive displacement compressors for duties requiring high heads at low flowrates.There are very few mathematical models in the literature that explain the behaviour of regenerative turbomachines and predict the performance. Most of these models assumed incompressible flow, thus limiting their use to only pumps and blowers. Moreover, they needed extensive experimental support for performance prediction. Hence, it is very interesting from an industrial point of view to find efficient theoretical means that are able to forecast regenerative compressor performances, using easy to find geometric and fluid dynamic parameters.A compressible flow theory is thus presented for the first time in this paper to describe complex three-dimensional corkscrew flow patterns in regenerative compressors. Conventional RFC were designed with radial, non-radial or semicircular impeller blades. In the present investigation, the authors have discussed RFCs with aerofoil blades and an annular flow channel containing a core to direct circulating flow to the blades with a minimum amount of losses.The effects of various geometric elements on the performance of RFCs are studied. All the major sources of losses in blade and channel region are identified. Governing equations for the flow in the compressor are derived and a performance prediction code based on governing equations and loss models is developed. Theoretical performance results are compared with published test data on aerofoil blade RFCs. Based on sensitivity analysis from the code, design changes are suggested for performance improvement.
Incorrect NICS-Based Prediction on the Aromaticity of the Pentalene Dication
Authors: Aihara Jun-ichi 
Published: January 2004

Abstract
Nucleus-independent chemical shift (NICS) values do not always reflect aromaticity. The pentalene dication exhibits large negative NICS values at the two ring centers although it is antiaromatic with a large negative topological resonance energy (TRE).
Synthesis of Mono- and Tri-Nuclear Ruthenium Carbonyl Complexes Containing the Pyridine-2-thiolato Ligand and Reactivity of a Bis(pyridine-2-thiolato) Chelated Ruthenium Dicarbonyl Complex with a Novel Cobalt-Containing Diphosphine Ligand
Authors: Hong Fung-E , Chang Yu-Chang , Chen Shu-Chun 
Published: January 2004

Abstract
The reaction of 3-cyano-4,6-dimethyl-pyridine-2-thiol with Ru3(CO)12 in toluene at 55 °C for 20 h gave three complexes: [Ru3(CO)10(μ-H)(μ-4,6-CH3-3-CN-2-S-py)] 5, [Ru(4,6-CH3-3-CN-py-κN-thiol-κS)2(CO)2] 7 and presumably [Ru3(CO)9(μ-H)(μ-4,6-CH3-3-CN-2-S-py)] 6. The deprotonated mercaptopyridine acts either as a bridging ligand in 5 and 6 or as a chelating ligand in 7. Further reaction of 7 with a novel cobalt-containing diphosphine ligand, [Co2(CO)4{μ-PPh2CH2PPh2}{μ-PPh2C≡CPPh2}] 8,1 probably resulted in the formation of probably a 8-chelated complex, [Ru(μ-4,6-CH3-3-CN-2-S-py)(4,6-CH3-3-CN-2-S-py-κS)(PPh2CH2PPh2)({μ-PPh2CH2PPh2}Co2(CO)4{μ-PPh2C≡CPPh2})] 10. All the compounds were characterized by spectroscopic means; furthermore, compounds 5 and 7 were studied by X-ray diffraction methods.
A Priori Assessment of the Maximum Possible Entrainment Effect Attainable during Preferential Crystallization. The Case of the Simultaneous Resolution of (±)-Ephedrine and (±)-Mandelic Acid
Authors: Dufour Fabrice , Perez Guy , Coquerel Gérard 
Published: January 2004

Abstract
The strong link observed between the detection of unstable or metastable racemic compounds in the systems studied and the maximum entrainment effect attainable during preferential crystallization (PC) (assessed by the maximum value of the enantiomeric excess of the mother solution at the end of PC (eefmax)) is confirmed by the results obtained with the simultaneous resolution of enantiomorphous p and p′ salts of (±)-ephedrine and (±)-mandelic acid (eefmax = 10.6% with no racemic compound detected). The detection of such a racemic compound indicates that strong heterochiral interactions at one or more (hkl) crystal–mother liquor interfaces are favorable to the 2D nucleation of the counter enantiomer as soon as its local supersaturation at these interfaces (β*hkl) attains a threshold above which the desorption of a docked counter-enantiomer molecule is no longer probable. Therefore, the mode and the rate of stirring must be optimized in order to keep β*hkl as close as possible to the overall supersaturation of the counter enantiomer β*bulk, while minimizing the damaging effects on the particles. The crystal structures of an unstable racemic compound and of a new polymorphic form of 1-phenylethylammonium hydratropate salts are reported and contribute to the understanding of the limited entrainment effect (eefmax = 5.2%).
Spin-Probe Study on the Dynamics and Distribution of Solution Molecules in the Nano-Channel of MCM-41
Authors: Okazaki Masaharu , Toriyama Kazumi , Sawaguchi Naoya , Oda Kiichi 
Published: January 2004

Abstract
The ESR spectrum of a spin-probe in 2-propanol, which was condensed into the nano-channel of MCM-41 from its vapor, showed three well-separated nitrogen hyperfine lines. This observation indicates that the system exists in the liquid state in the nano-channel, though the rotational diffusion of the spin probe molecule is considerably suppressed and anisotropic. In a mixed solvent composed of 2-propanol and cyclohexane, on the other hand, the ESR spectrum for the system prepared by the above procedure comprised two components, indicating that the solution is phase-separated in the nano-channel. When all of the space in the MCM-41 layer, including that among the granules, is filled with the solution, the molecules obtain a higher mobility and phase separation is suppressed even in the nano-channel. The distribution and dynamics of the solution molecules are discussed.
Excited High-Spin Quartet (S = 3/2) State of a Novel π-Conjugated Organic Spin System, Pyrene–Verdazyl Radical
Authors: Teki Yoshio , Kimura Mituhiro , Narimatsu Shinsuke , Ohara Keishi , Mukai Kazuo 
Published: January 2004

Abstract
The excited high-spin quartet (S = 3/2) state of the intramolecular triplet–radical pair between the excited triplet state of pyrene and a dangling verdazyl radical was reported. A novel verdazyl radical with the pyrene moiety was designed and synthesized. The time-resolved ESR spectrum and a DFT calculation show the photo-induced ferromagnetic spin alignment between the excited triplet state of the pyrene moiety and the dangling verdazyl radical. This is the first observation of the high-spin (S &gt; 1) excited state of the π-conjugated pyrene–radical pair.