bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of size and behavior on aerial performance of two species of flying snakes (Chrysopelea)
Authors: Socha John J. , LaBarbera Michael 
Published: May 2005

SUMMARYAerial locomotion in snakes (genus Chrysopelea) is kinematically distinct from any other type of gliding or powered flight, with prominent,high amplitude body undulations visually dominating the behavior. Because it is not known how flying snakes produce aerodynamic forces in flight, the factors that determine snake flight performance are not clear. In this study,the effects of size and behavior on aerial performance were examined both within a species (C. paradisi) and between two species (C. paradisi and C. ornata), using stepwise multiple regressions to identify relevant variables. Smaller C. paradisi traveled farther than larger snakes at lower sinking speeds, with trajectories that shallowed more quickly and reached lower minimum glide angles. Although wing loading increased faster than expected for isometric size increase, wing loading per se was not responsible for performance differences between large and small snakes. Snakes with higher interactions between relative undulation amplitude and body size transitioned out of the initial acceleration phase at higher airspeeds and sinking speeds, and attained higher maximum airspeeds and horizontal speeds; snakes that used higher average relative amplitudes transitioned out of the initial acceleration phase at higher horizontal speeds. Undulation frequency was not significantly related to any performance variable within C. paradisi and was not significantly different between the two species, suggesting that this variable (in contrast to relative undulation amplitude) may have a minor influence on the aerodynamic mechanism of force production in snake flight. C. paradisi and C. ornata differed significantly in most performance comparisons. C. ornata were more massive than C. paradisi at any given body length and in general exhibited poorer gliding performance than C. paradisi. This study contributes towards understanding how an unconventional body form and kinematics can produce a novel mode of aerial locomotion in a vertebrate glider.
Physiological control of diving behaviour in the Weddell sealLeptonychotes weddelli: a model based on cardiorespiratory control theory
Authors: Stephenson Richard 
Published: May 2005

SUMMARYDespite being obligate air breathers, many species of marine mammal are capable of spending most of their lives submerged in water. How they do this has been a subject of intense interest to physiologists for over a century,yet we still do not have a detailed understanding of the physiological mechanisms underlying this behaviour. What are the proximate mechanisms that trigger the 'decisions' to submerge and return to the surface? The present study proposes a model intended to address this question, based on fundamental concepts of cardiorespiratory control. Two basic hypotheses are examined by computer simulation, using a mathematical model of the mammalian cardiorespiratory control system with parameter values for an adult Weddell seal: (1) that the control of diving can be considered to be a respiratory control problem, and (2) that dives are initiated and maintained by disfacilitation of respiratory drive, not inhibition. Computer simulations confirmed the plausibility of these hypotheses. Simulated diving behaviour and physiological responses (ventilation, cardiac output, blood and tissue gas tensions) were consistent with published data from freely diving Weddell seals. Dives up to the estimated aerobic dive limit (ADL, 18-25 min) could be simulated without the need for active inhibition of breathing in this model. This theoretical analysis suggests that the most important physiological adjustments occur during the surface interval phase of the dive cycle and include hyperventilation accompanied by high cardiac output, appropriate regulation of cerebral blood flow and central chemoreceptor threshold shifts. During dives, cardiac output, distribution of peripheral blood flow, splenic contraction and peripheral chemoreflex drives were found to modulate physiological and behavioural responses, but were not essential for simulated dives to occur. The main conclusion from this study is that the central chemoreceptor may be an important mechanism involved in the regulation of diving behaviour, implying that CO2, not O2, is the key regulatory variable in this model. This model includes and extends the ADL concept and suggests an explicit mechanism by which the respiratory control system may play a central role in the regulation of diving behaviour. It is likely that respiratory mechanisms are an important component of a hierarchical behavioural control system and further studies are required to test the qualitative and quantitative validity of the model.
Colouration in crab spiders: substrate choice and prey attraction
Authors: Heiling Astrid M. , Chittka Lars , Cheng Ken , Herberstein Marie E. 
Published: May 2005

SUMMARY
Australian crab spiders Thomisus spectabilis ambush pollinating insects, such as honeybees (Apis mellifera) on flowers, and can change their body colour between yellow and white. It is traditionally assumed that the spiders change their colour to match the flower colour, thus rendering them cryptic to insect prey. Here, we test this assumption combining state-of-the-art knowledge of bee vision and behavioural experiments.
In the field, yellow spiders are only found on yellow daisies(Chrysanthemum frutescens), whereas white spiders are found on yellow and white daisies. These field patterns were confirmed in the laboratory. When given the choice between white and yellow daisies, yellow spiders preferred yellow daisies, whereas white spiders showed only a slight but non-significant preference for white flowers. Thus, T. spectabilis select background colours according to their own body colour. When viewed from a distance, bees use an achromatic signal produced by their green receptors for target detection. Through this visual channel, white spiders on white flowers, and yellow spiders on yellow flowers are virtually undetectable. From a closer distance of a few centimetres, when bees evaluate colour contrast, the combination of spider colour against different flower backgrounds affected the response of honeybees, but not in ways predicted by a classical crypsis/conspicuousness interpretation. Yellow spiders on yellow flowers are not perfectly matched when interpreted through the colour vision of a honeybee. Nevertheless, honeybees showed indifference to the presence of a spider, equally landing on vacant or spider-occupied flowers. Likewise, white spiders are poorly hidden on white flowers, as white spiders reflect ultraviolet light strongly, while white flowers do not. Surprisingly, bees are attracted to this contrast, and significantly more honeybees preferred white flowers occupied by white spiders. White spiders on yellow flowers produce the highest colour contrast and bees again preferred spider-occupied flowers. Yellow spiders on white flowers were the only pairing where bees rejected spider-occupied flowers, especially in cases where the contrast between the two was relatively strong. Thus, T. spectabilis select flower colours adaptively in a way that deceives honeybees, or at least does not deter them.
A comparative evaluation of 238Pu determination in NIST-SRM-947-Pu by alpha spectrometry and thermal ionization mass spectrometry
Authors: Alamelu D. , Shah P. M. , Aggarwal S. K. 
Published: May 2005

Summary
A comparative evaluation of 238Pu determination in NIST-SRM-947-Pu isotopic reference material by alpha spectrometry and thermal ionization mass spectrometry (TIMS) is presented. Electrodeposited sources with geometric progression (G.P.) method to account for tail contribution were used in alpha spectrometry. In TIMS, the recently developed approach of using 235U as a monitor isotope in interfering element correction methodology was employed to account for the isobaric interference of 238U at 238Pu. The atom % abundance of 238Pu determined by both the methods is in good agreement with each other but is higher than that quoted by NIST in the reference material SRM-947-Pu.
Advanced Laser Imaging Diagnostics in Combustion
Authors: Schulz C. 
Published: May 2005

Abstract
Laser-based imaging diagnostics allow the quantitative determination of scalar fields (concentrations, temperature) in combustion environments. Beyond instantaneous two-dimensional distributions, multi-dimensional imaging can provide simultaneous information about concentration of more than one species and temperature, about three-dimensional concentration and temperature distributions as well as the temporal evolution of reactions, flows and evaporation processes. Various examples in combustion environments are presented.
Action Spectroscopy and Predissociation of Vibrationally Excited C2HD
Authors: Ganot Yuval , Rosenwaks Salman , Bar Ilana 
Published: May 2005

Abstract
H and D photofragments, produced via vibrationally mediated photodissociation of jet-cooled C2HD allowed measurement of vibrational and vibronic excitation action spectra of the parent as well as H and D Doppler profiles. The initial vibrational preparation at energies around 9700 cm−1 enhanced C—H and C—D bond cleavage for transitions from an initially excited bent state to the upper A
~ state, rather than from a close lying state containing three C—H stretch quanta, due to favorable Franck—Condon factors for the former. The bound region of the A
~ state was accessed, resulting in non-adiabatic dissociation and slight preferential C—H over C—D bond cleavage.
Rovibrational Energy Transfer in the 4νCH Manifold of Acetylene, Viewed by IR-UV Double Resonance Spectroscopy. 3. State-to-State J-Resolved Kinetics
Authors: Payne Mark A. , Milce Angela P. , Frost Michael J. , Orr Brian J. 
Published: May 2005

Abstract
Time-resolved infrared-ultraviolet double resonance (IR-UV DR) spectroscopy is used to study the kinetics of collision-induced state-to-state molecular energy transfer between rovibrational states in the 12700-cm−1 4νCH manifold of the electronic ground state of acetylene (C2H2). Particular initial and final rovibrational J-states are prepared and monitored by a pair of tunable laser pulses (IR PUMP and UV PROBE) and the kinetic results recorded by continuously varying the time delay between those pulses at a set sample pressure. After allowing for collision-induced quenching of fluorescence and mass transfer from the IR-UV optical excitation zone (by beam flyout and diffusion), an array of kinetic data for J-resolved energy-transfer channels can be interpreted by means of a mechanistically structured master-equation model. This paper focuses on kinetics derived by probing C2H2 in its 4νCH
J = 12 state (which is affected by intramolecular perturbations and implicated in unusual collision-induced quasi-continuous background effects) and J-resolved collision-induced rovibrational energy transfer with both even ΔJ and (supposedly forbidden) odd ΔJ.
Conditional Velocity Measurements by Simultaneously Applied Laser Doppler Velocimetry and Planar Laser-Induced Fluorescence in a Swirling Natural Gas/Air Flame
Authors: Nauert A. , Dreizler A. 
Published: May 2005

Abstract
By applying joint velocity/scalar measurements, conditional mean axial and radial velocity components are determined in the vicinity of the turbulent flame front of a premixed swirling natural gas/air flame. Two velocity components are measured by laser Doppler velocimetry (LDV) simultaneously with planar laser-induced fluorescence (PLIF) monitoring the hydroxyl radical (OH). The spatial OH distribution is used to tag the instantaneous position of the flame front and can be thereby used to derive conditional velocities. From these measurements the turbulent flux of the mean progress variable is determined which is an important quantity to model premixed flames. One important finding is that for this rather complex but technically realistic geometry, at some locations in the flame brush conditional axial and radial velocities show different behaviour. Thus gas expansion effects can dominate axially whereas in radial direction turbulent fluctuations determine the direction of turbulent transport.
NO Reburn and Formation Chemistry in Methane Diffusion Flames
Authors: Driscoll J. Joshua , Sick Volker , Farrow Roger L. , Schrader Paul E. , Rizos K.-A. , Lindstedt R. Peter 
Published: May 2005

Abstract
We have applied time-resolved picosecond linear laser-induced fluorescence to obtain spatially resolved profiles of NO in laminar methane/air and methane/nitric oxide/air counterflow diffusion flames at atmospheric pressure. Temperature profiles have been measured with broadband CARS of nitrogen. Flames at strain rates from 59 s−1 to 269 s−1 were studied to characterize the strain rate dependence of the NO concentration. The work shows that NO concentrations decrease with increasing strain rate. Comparisons have been made with predicted NO levels obtained using two different chemical kinetic mechanisms (Lindstedt and co-workers and GRI-Mech. 3.0). Computed concentrations are shown to be in good agreement with experimental data. The addition of up to 600 ppm NO to the fuel did permit an assessment of differences in the reburn chemistry between the two mechanisms.
SACM/CT Study of Product Energy Distributions in the Dissociation of n-Propylbenzene Cations
Authors: Troe J. , Ushakov V.G. , Viggiano A. A. 
Published: May 2005

Abstract
The distribution of translational, rotational, and vibrational energies in the fragments (benzylium ions and ethyl radicals) of the dissociation of n-propylbenzene cations has been determined by statistical adiabatic channel model/classical trajectory (SACM/CT) calculations. The reaction was treated by CT calculations of capture processes for transitional modes, starting with specified fragment energies. A short-range valence/long-range ion-induced dipole potential model for the transitional modes was employed. The derived distributions approach the results from phase space theory (PST) at small energies and angular momenta. At larger energies and angular momenta, the shapes of the distribution functions remain similar to those from PST; however, the average translational, rotational, and vibrational energies of the fragments increasingly differ from PST predictions. The present results are consistent with separate SACM/CT calculations on the same potential of specific rate constants k(E,J) and thermally averaged rate constants k
∞(T) of the dissociation/recombination reaction.
Evaluation of adrenal function in patients with growth hormone deficiency and hypothalamic–pituitary disorders: comparison between insulin-induced hypoglycemia, low-dose ACTH, standard ACTH and CRH stimulation tests
Authors: Maghnie M , Uga E , Temporini F , Di Iorgi N , Secco A , Tinelli C , Papalia A , Casini MR , Loche S 
Published: May 2005

Objectives: Patients with organic growth hormone deficiency (GHD) or with structural hypothalamic–pituitary abnormalities may have additional anterior pituitary hormone deficits, and are at risk of developing complete or partial corticotropin (ACTH) deficiency. Evaluation of the integrity of the hypothalamic–pituitary–adrenal axis (HPA) is essential in these patients because, although clinically asymptomatic, their HPA cannot appropriately react to stressful stimuli with potentially life-threatening consequences.
Design and methods: In this study we evaluated the integrity of the HPA in 24 patients (age 4.2–31 years at the time of the study) with an established diagnosis of GHD and compared the reliability of the insulin tolerance test (ITT), short synacthen test (SST), low-dose SST (LDSST), and corticotropin releasing hormone (CRH) test in the diagnosis of adrenal insufficiency.
Results: At a cortisol cut-off for a normal response of 550 nmol/l (20 μg/dl), the response to ITT was subnormal in 11 subjects, 6 with congenital and 5 with acquired GHD. Four patients had overt adrenal insufficiency, with morning cortisol concentrations ranging between 66.2–135.2 nmol/l (2.4–4.9 μg/dl) and typical clinical symptoms and laboratory findings. In all these patients, a subnormal cortisol response to ITT was confirmed by LDSST and by CRH tests. SST failed to identify one of the patients as adrenal insufficient. In the seven asymptomatic patients with a subnormal cortisol response to ITT, the diagnosis of adrenal insufficiency was confirmed in one by LDSST, in none by SST, and in five by CRH tests. The five patients with a normal cortisol response to ITT exhibited a normal response also after LDSST and SST. Only two of them had a normal response after a CRH test. In the seven patients with asymptomatic adrenal insufficiency mean morning cortisol concentration was significantly higher than in the patients with overt adrenal insufficiency. ITT was contraindicated in eight patients, and none of them had clinical symptoms of overt adrenal insufficiency. One of these patients had a subnormal cortisol response to LDSST, SST, and CRH, and three exhibited a subnormal response to CRH but normal responses to LDSST and to SST.
Conclusion: We conclude that none of these tests can be considered completely reliable for establishing or excluding the presence of secondary or tertiary adrenal insufficiency. Consequently, clinical judgment remains one of the most important issues for deciding which patients need assessment or re–assessment of adrenal function.
The Large Loop Repair and Mismatch Repair Pathways of Saccharomyces cerevisiae Act on Distinct Substrates During Meiosis
Authors: Jensen Linnea E , Jauert Peter A , Kirkpatrick David T 
Published: May 2005

Abstract
During meiotic recombination in the yeast Saccharomyces cerevisiae, heteroduplex DNA is formed when single-stranded DNAs from two homologs anneal as a consequence of strand invasion. If the two DNA strands differ in sequence, a mismatch will be generated. Mismatches in heteroduplex DNA are recognized and repaired efficiently by meiotic DNA mismatch repair systems. Components of two meiotic systems, mismatch repair (MMR) and large loop repair (LLR), have been identified previously, but the substrate range of these repair systems has never been defined. To determine the substrates for the MMR and LLR repair pathways, we constructed insertion mutations at HIS4 that form loops of varying sizes when complexed with wild-type HIS4 sequence during meiotic heteroduplex DNA formation. We compared the frequency of repair during meiosis in wild-type diploids and in diploids lacking components of either MMR or LLR. We find that the LLR pathway does not act on single-stranded DNA loops of &lt;16 nucleotides in length. We also find that the MMR pathway can act on loops up to 17, but not &gt;19, nucleotides in length, indicating that the two pathways overlap slightly in their substrate range during meiosis. Our data reveal differences in mitotic and meiotic MMR and LLR; these may be due to alterations in the functioning of each complex or result from subtle sequence context influences on repair of the various mismatches examined.
The Genetic Basis of Resistance to Anticoagulants in Rodents
Authors: Pelz Hans-Joachim , Rost Simone , Hünerberg Mirja , Fregin Andreas , Heiberg Ann-Charlotte , Baert Kristof , MacNicoll Alan D , Prescott Colin V , Walker Anne-Sophie , Oldenburg Johannes , Müller Clemens R 
Published: May 2005

Abstract
Anticoagulant compounds, i.e., derivatives of either 4-hydroxycoumarin (e.g., warfarin, bromadiolone) or indane-1,3-dione (e.g., diphacinone, chlorophacinone), have been in worldwide use as rodenticides for &gt;50 years. These compounds inhibit blood coagulation by repression of the vitamin K reductase reaction (VKOR). Anticoagulant-resistant rodent populations have been reported from many countries and pose a considerable problem for pest control. Resistance is transmitted as an autosomal dominant trait although, until recently, the basic genetic mutation was unknown. Here, we report on the identification of eight different mutations in the VKORC1 gene in resistant laboratory strains of brown rats and house mice and in wild-caught brown rats from various locations in Europe with five of these mutations affecting only two amino acids (Tyr139Cys, Tyr139Ser, Tyr139Phe and Leu128Gln, Leu128Ser). By recombinant expression of VKORC1 constructs in HEK293 cells we demonstrate that mutations at Tyr139 confer resistance to warfarin at variable degrees while the other mutations, in addition, dramatically reduce VKOR activity. Our data strongly argue for at least seven independent mutation events in brown rats and two in mice. They suggest that mutations in VKORC1 are the genetic basis of anticoagulant resistance in wild populations of rodents, although the mutations alone do not explain all aspects of resistance that have been reported. We hypothesize that these mutations, apart from generating structural changes in the VKORC1 protein, may induce compensatory mechanisms to maintain blood clotting. Our findings provide the basis for a DNA-based field monitoring of anticoagulant resistance in rodents.
The Origin of Multiple B Mating Specificities in Coprinus cinereus
Authors: Riquelme Meritxell , Challen Michael P , Casselton Lorna A , Brown Andrew J 
Published: May 2005

Abstract
Mushrooms, such as Coprinus cinereus, possess large families of pheromones and G-protein-coupled receptors that are sequestered at the B mating-type locus and whose function is to confer vast numbers of different mating types. This ability results from complex patterns of cognate and noncognate pheromone/receptor pairings, which potentially offer a unique insight into the molecular interaction between receptor and ligand. In this study we have identified many more members of these families by molecular analysis of strains collected worldwide. There are three groups of genes at each B locus. We have identified two alleles of group 1, five alleles of group 2, and seven alleles of group 3, encoding in total 14 different receptors and 29 different pheromones. The specificity of many newly identified alleles was determined by transformation analysis. One striking finding was that receptors fall into groups based on sequence homology but these do not correspond to the groups defined by position, indicating that complex evolutionary processes gave rise to the B loci. While additional allelic versions may occur in nature, the number of B specificities possible by combination of the alleles that we describe is 70, close to previous estimates based on population analysis.
The Molecular Chaperone Sse1 and the Growth Control Protein Kinase Sch9 Collaborate to Regulate Protein Kinase A Activity in Saccharomyces cerevisiae
Authors: Trott Amy , Shaner Lance , Morano Kevin A 
Published: May 2005

AbstractThe Sch9 protein kinase regulates Hsp90-dependent signal transduction activity in the budding yeast Saccharomyces cerevisiae. Hsp90 functions in concert with a number of cochaperones, including the Hsp110 homolog Sse1. In this report, we demonstrate a novel synthetic genetic interaction between SSE1 and SCH9. This interaction was observed specifically during growth at elevated temperature and was suppressed by decreased signaling through the protein kinase A (PKA) signal transduction pathway. Correspondingly, sse1Δ sch9Δ cells were shown by both genetic and biochemical approaches to have abnormally high levels of PKA activity and were less sensitive to modulation of PKA by glucose availability. Growth defects of an sse1Δ mutant were corrected by reducing PKA signaling through overexpression of negative regulators or growth on nonoptimal carbon sources. Hyperactivation of the PKA pathway through expression of a constitutive RAS2 allele likewise resulted in temperature-sensitive growth, suggesting that modulation of PKA activity during thermal stress is required for adaptation and viability. Together these results demonstrate that the Sse1 chaperone and the growth control kinase Sch9 independently contribute to regulation of PKA signaling.