bluuebunny/crossref_metadata_2025 huggingface dataset:
The ubiquitous zonal jets in the atmospheres of giant planets and Earth's oceans
Authors: Galperin Boris , Nakano Hideyuki , Huang Huei‐Ping , Sukoriansky Semion
Published: June 2004

Recent eddy‐permitting simulations of the North Pacific Ocean have revealed robust patterns of multiple zonal jets that visually resemble the zonal jets on giant planets. We argue that this resemblance is more than just visual because the energy spectrum of the oceanic jets obeys a power law that fits spectra of zonal flows on the outer planets. Remarkably, even the non‐dimensional proportionality coefficient, CZ, determined by data under that spectral law, appears to be constant for all cases and approximately equal to 0.5. These results indicate that the multiple jet sets in the ocean and in the atmospheres of giant planets are governed by the same dynamics characterized by an anisotropic inverse energy cascade, i.e., the flow of energy from isotropic small‐scale eddies to anisotropic large‐scales structures, as well as the unique anisotropic spectrum. Implications of these results for climate research and future designs of observational missions are discussed.
A possible plankton wave in the Indian Ocean
Authors: Srokosz Meric A. , Quartly Graham D. , Buck Justin J. H.
Published: June 2004

The existence of waves in oceanic plankton populations has been conjectured on theoretical grounds. We report the first open ocean observations of a possible plankton wave in the Indian Ocean, seen in satellite ocean colour data. The chlorophyll feature travels from west to east, in the opposite direction to the mean flow and the Rossby wave and eddy propagation direction. For the strongest observed event, in February to April 1999, the wave propagates in the latitude band ∼22–30°S away from Madagascar and dies out at ∼75°E.
Halo of low ice concentration observed over the Maud Rise seamount
Authors: Lindsay R. W. , Holland D. M. , Woodgate R. A.
Published: June 2004

A distinctive halo of low sea ice concentration has been observed above the Maud Rise seamount in the eastern Weddell Sea. The 300–km circular halo is seen most clearly in the monthly mean ice concentration for the months July through November. The mean was computed from satellite‐based passive microwave measurements over a 23–year period. The halo is most distinct in October; even then, however, the mean ice concentration in the halo is just 10% less than in the center, where it is very near 100%. The halo may reflect the existence of a Taylor cap circulation over the seamount or other topographically induced mechanisms.
The atmospheric helium isotope ratio: Is it changing?
Authors: Lupton John , Evans Leigh
Published: June 2004

We have compared the helium isotope ratio of samples of Pacific marine air collected over the 30‐year period from 1973 to 2003 against a secondary geothermal gas standard and also against a running air standard. The results are consistent with zero rate of change for atmospheric 3He/4He. When the errors are taken into account, the rate of change in the air 3He/4He ratio is between −0.0102 and +0.0019 %/year. At the most this corresponds to a 0.3% change in the air 3He/4He ratio over the past 3 decades, which is at or below the detection limit of most laboratories. While there may be a small decrease in air 3He/4He due to anthropogenic release of 4He associated with use of fossil fuels, this decrease is not large enough to prevent the use of air helium as an isotopic standard.
Detection of ocean wave groupiness from spaceborne synthetic aperture radar
Authors: Nieto Borge J. C. , Lehner S. , Niedermeier A. , Schulz‐Stellenfleth J.
Published: June 2004

In recent years a number of remote sensing techniques capable to provide two‐dimensional information of the sea surface have been applied to describe sea states. This information is obtained from the estimation of the directional wave number spectrum. However, the wave number spectrum is not sufficient for a complete description of sea states. The analysis of some phenomena such as wave grouping, detection of individual waves, maximum wave heights, etc., needs a complementary study, which has been carried out historically in the temporal domain from buoy records. In two dimensions (e.g., the spatial domain), the complementary analysis of those phenomena can be carried out in the spatial domain rather than the temporal domain. In this work, two methods to analyze wave groupiness in the spatial domain from sea surface images are presented: The first method is based on the two‐dimensional generalization of the Smoothed Instantaneous Wave Energy History (SIWEH) function, which had been originally developed to analyze wave groupiness for wave elevation time series. The second method uses the estimation of the wave envelope in two dimensions to extract wave grouping parameters. Assuming that the wave fields are Gaussian stochastic processes, both methods are applied to ERS‐2 synthetic aperture radar (SAR) and ENVISAT advanced SAR (ASAR) images of the sea surface, where only cases with almost range traveling waves are considered in order to avoid strong nonlinearities in the SAR imaging mechanisms. The obtained results shown that spaceborne SAR can be used to extract wave grouping information on global scale.
A non-Gaussian stochastic model to describe passive tracer dispersion and its comparison to a direct numerical simulation
Authors: Iliopoulos Ilias , Hanratty Thomas J.
Published: June 2004

Dispersion of solid particles in three dimensions in a fully developed nonhomogeneous turbulent flow in a channel is studied. The particles enter the field on a plane at a distance of 40 wall units from the bottom wall. Data are obtained by carrying out experiments in a direct numerical simulation. The relative role of turbulence in dispersing the particles is examined. The paper explores the use of a stochastic Lagrangian model to describe solid particle dispersion. More specifically, each particle is tracked individually and through the employment of Ito calculus a modified Langevin equation is utilized to model the fluid fluctuations seen by a solid particle. The assumption of isotropy and homogeneity was not used in the formulation of the nondeterministic term in the model. All of the statistical parameters, with the exception of the time scales, are obtained from Eulerian statistics. The understanding of the influence of spatially varying time scale emerges as a central problem. Good agreement is obtained by making simple assumptions about the spatial variation of the time scales.
Three-dimensionalization of freely-decaying two-dimensional turbulence
Authors: Ngan K. , Straub D. N. , Bartello P.
Published: June 2004

The three-dimensionalization of freely-decaying two-dimensional turbulence is studied numerically. Using two different basic states, it is shown that the hyperbolic instability of steady mixing layers generalizes to unsteady flow. The growth of three-dimensional (3D) perturbations is interpreted in terms of a “pressureless” analysis in which horizontal pressure gradients are neglected and the underlying physical mechanism is advective in nature. For a steady, pressureless base flow the (asymptotic) growth rate is exactly determined, in a few special cases, by variants of the so-called Weiss criterion; more generally, local growth rate estimates are obtained. For freely-decaying two-dimensional turbulence there is analogous behavior: while the 3D perturbation remains small the pressureless approximation holds at large horizontal scales and local growth rate estimates apply. The pressureless modes have a determining influence on the growth (the damping effect of the horizontal pressure gradient is small).
Raman scattering system for a laser heated diamond anvil cell
Authors: Zhou Qiang , Ma Yanzhang , Cui Qiliang , Cui Tian , Zhang Jian , Xie Yuanliang , Yang Kaifeng , Zou Guangtian
Published: June 2004

A Raman scattering system has been developed for in situ measurements under high pressure and high temperature (HPHT). This system integrates micro-Raman spectroscopy equipment with a double-sided laser heating system for a diamond anvil cell. The laser heating system allows one to generate P–T conditions over one megabar and thousands of degree Kelvin. In this article, in situ HPHT Raman measurements have been carried out on NaBi(WO4)2 to 12.2 GPa and 1658 K.
Biomagnetic flow in a curved square duct under the influence of an applied magnetic field
Authors: Papadopoulos P. K. , Tzirtzilakis E. E.
Published: June 2004

The laminar incompressible fully developed biomagnetic (blood) flow in a curved square duct under the influence of an applied magnetic field is studied. The mathematical formulation is based on the model of biomagnetic fluid dynamics which is consistent with the principles of ferrohydrodynamics. According to this formulation blood is considered as an electrically nonconducting, homogeneous, and Newtonian magnetic fluid. For the numerical solution of the problem, which is described by a coupled, nonlinear system of partial differential equations, with their appropriate boundary conditions, the SIMPLE method is used. The results indicate that the axial velocity as well as the secondary flow at the transverse plane are appreciably influenced and indicate that the magnetic field could be used for controlling the blood flow by magnetic means.
Application of a static quadrupole deviator to the deposition of size-selected cluster ions from a laser vaporization source
Authors: Alayan R. , Arnaud L. , Bourgey A. , Broyer M. , Cottancin E. , Huntzinger J. R. , Lermé J. , Vialle J. L. , Pellarin M. , Guiraud G.
Published: June 2004

An electrostatic quadrupole deviator is used to separate charged from neutral clusters produced by a laser vaporization source. Because of their rather constant velocity, this device which is basically an energy selector also acts as an efficient mass filter. We have simulated and studied its capability to generate beams of size-selected charged clusters. Typical beam currents of a few tens of pA allow the formation of two-dimensional cluster deposits within a few minutes. Platinum and indium clusters are deposited on electron microscopy grids coated with an amorphous carbon film. For low-density assemblies of particles in the nanometer range, size histograms are discussed in relation with the mass selectivity of the apparatus. An upper limit for the dispersion of selected cluster diameters is found to be of the order of ±8% which is at least five times better than the dispersion of neutral species.
Effects of surfactant on droplet spreading
Authors: Clay Matthew A. , Miksis Michael J.
Published: June 2004

The effects of surfactant and temperature on the spreading of a viscous droplet are studied. Lubrication theory is used to develop a model for the evolution of the droplet. The surfactant is assumed to be insoluble and transport onto and off of the droplet interface at the contact line is allowed. A linear temperature gradient plus a gradient in the surface energy are allowed along the substrate. We find that these effects together can increase the speed of the translation of the droplet. We also find that allowing the static contact angle to vary with the surfactant concentration and temperature, as described by Young’s law, can speed up droplet motion. When contact angle hysteresis is allowed, it is possible for the droplet to stop moving when surfactant transport is allowed along the interface.
On the amplification of small disturbances in a channel flow with a normal magnetic field
Authors: Airiau Christophe , Castets Mélanie
Published: June 2004

Optimal perturbations are investigated in a magnetohydrodynamic flow bounded by perfectly insulating or conducting walls. The parallel channel flow submitted to uniform, normal magnetic field is taken as an example. The stability equations (linearized Navier–Stokes and Maxwell equations) are solved simultaneously, because of the natural existence of a coupling between them. Exponential instability is studied first to set ideas and to fix some reference magnetic Prandtl and magnetic Reynolds numbers. Then, optimal perturbations are searched for by employing the approach first proposed by Butler and Farrell [Phys. Fluids A 4, 1637 (1992)]. The shape of the optimally perturbed velocity is poorly affected by the magnetic field; however, the magnetic field is found to stabilize both exponential instability and algebraically growing perturbations. The critical Reynolds numbers in the presence of magnetic fields can be very large and it is thus possible to find very significant transient growth in subcritical condition. On the basis of the linear theory developed here, it is found that the gain experienced by the flow at the value of the Reynolds number at which transition is experimentally observed is constant, i.e., independent of the other dimensionless parameters.
Development of a reliable and simple pressure wave generator for pulse tube refrigerators
Authors: Karunanithi R. , Jacob S. , Kasthurirengan S. , Behera Upendra , Nadig D. S.
Published: June 2004

The pressure wave generator is a critical component of a pulse tube refrigerator. Conventionally either a solenoid operated electromagnetic valve or a rotary valve driven by a hermetically sealed motor is used for this. In this article, we present a novel pressure wave generator design based on cam operated valves for use with pulse tube refrigerators. This, when coupled with an inverter drive (variable frequency drive), forms a versatile pressure wave generator in the range between 1 and 10 Hz. In a single stage double inlet pulse tube using this type of pressure wave generator, refrigeration power of about 6 W at 77 K and a no load temperature of about 42 K were obtained. The above results are comparable to those obtained with pulse tube systems based on other two types of pressure wave generators. While the rotary valve based pressure wave generator is prone to developing leaks at the rotating seal, the solenoid valve based system cannot be operated continuously due to coil failure. The cam operated valve based pressure wave generator overcomes the above shortfalls of rotary valve and solenoid valve type pressure generators and is well suited for continuous operation of the refrigerator.
Double quartz tuning fork sensor for low temperature atomic force and scanning tunneling microscopy
Authors: Heyde M. , Kulawik M. , Rust H.-P. , Freund H.-J.
Published: June 2004

A double quartz tuning fork sensor for low temperature ultrahigh vacuum atomic force and scanning tunneling microscopy is presented. The features of the new sensor are discussed and compared to a single asymmetric tuning fork assembly. In addition, a low temperature ac signal amplifier has been developed to pick up the oscillation amplitude of the tuning fork. Current consumption and amplification factor versus the supply voltage of the amplifier as well as the magnitude response of the sensor have been measured at room temperature, 77 and 4 K. Atomically resolved images of a Ag(111) surface and single Ag atoms on Ag(111) were recorded in the scanning tunneling microscopy mode. Initial atomic force measurements are shown that reveal step resolution on a NiAl(110) surface.
Chaining and dendrite formation of gold particles
Authors: Yuan Yong J. , Andrews Mike K. , Marlow Barry K.
Published: June 2004

Using the time-averaged dielectrophoretic force from an applied electric field, we have observed the assembly of gold colloid particles into nano/microwires, connections and dendrites according to location within different field regions of a lithographically patterned array of microelectrodes. The frequency of the fields has a marked effect on the structures. In situ inverse microscopy showed hydrodynamic flows, which probably arise from local heating and which play a significant part in shapes formed. Understanding and using the effects will allow the controlled fabrication and positioning of micro- and nanowires or connections at densities far above what is now achievable.
Vortex erosion in a shallow-water model
Authors: Louazel S. , Hua B. L.
Published: June 2004

The purpose of this paper is to study the erosion of eddies by filamentation in a shallow-water model where both fast and slow components of the dynamics coexist. In presence of inertia-gravity waves this filamentation process is indeed found to be altered. However, the information required to analyze the filamentation process is shown to be entirely captured by the slow component of the flow and regions of filament ejection can be identified from a diagnostic criterion based on instantaneous slow quantities. This is illustrated numerically in a reduced gravity model for an initial elliptic vortex of distributed potential vorticity in presence of Poincaré waves.
“Soft” bulk metallic glasses based on cerium
Authors: Zhang B. , Pan M. X. , Zhao D. Q. , Wang W. H.
Published: June 2004

CeAlNiCu alloys can be readily cast into glassy rods with up to 5mm in diameter. The Ce-based bulk metallic glasses (BMGs) exhibit a wide supercooled region up to 78K, very low glass transition temperature (Tg=359K), melting temperature (Tm=637K), and Debye temperature (θD=144K). Ultrasonic measurements demonstrate that these Ce-based BMGs are very soft, having the lowest elastic moduli in known BMGs. These features suggest that the “soft” BMGs are an ideal model system for investigating physical problems in glass transition, supercooled liquid and melt states, and have potential applications as a functional material as well.
Wavelength conversion in silicon using Raman induced four-wave mixing
Authors: Raghunathan V. , Claps R. , Dimitropoulos D. , Jalali B.
Published: June 2004

Conversion of digital- and analog-modulated optical signals from the 1550nm band to the 1300nm band is demonstrated in silicon waveguides. The conversion is based on parametric Stokes to anti-Stokes coupling using the Raman susceptibility of silicon.
Shear layer development in a three-dimensional compressible base flow
Authors: Boswell Brad A. , Dutton J. Craig
Published: June 2004

The structure and characteristics of the shear layer embedded in a three-dimensional, compressible, separated flow were investigated experimentally. The investigation focused on three primary areas: shear layer initiation at the base-corner separation point, development of the three-dimensional shear layer enclosing the recirculation region, and the turbulence structure near reattachment. The primary data presented are mean velocity and turbulence fluctuations measured using two-component laser-Doppler velocimetry. Initiation of the shear layer at the base-corner separation point results in an increase of all measured turbulent stresses, and a change in orientation of the turbulent structures. The shear layer growth rate is observed to vary with circumferential angle, with growth occurring at a much faster rate in the leeward plane than in the windward. Throughout the reattachment region, the turbulent stresses do not appear to diminish in the streamwise direction, contrary to previously published results for axisymmetric base flows. In addition, the reattachment phenomenon tends to slightly decrease overall turbulent structure organization.
Distribution of flowing fluids in a confined porous medium under microgravity conditions
Authors: Guo Boyun , Holder Donald W. , Carter Layne
Published: June 2004

Predicting distribution of flowing fluids in confined porous media under microgravity conditions is vitally important for optimal design of packed bubble column reactors in space stations. Existing correlations have been found inaccurate when applied to microgravity conditions. On the basis of Darcy’s law for two-phase flow, a simple mathematical model has been developed in this study. Sensitivity analyses with the model indicate that for a given combination of wetting and nonwetting fluid flow rates, fluid holdups are controlled by relative permeabilities. The effect of gravity on fluid holdup is influenced by the absolute permeability of the porous medium. Fluid distribution is affected by the temperature-dependent fluid properties and wall effect.
Carbon nanotube p-n junction diodes
Authors: Lee J. U. , Gipp P. P. , Heller C. M.
Published: June 2004

We demonstrate a single-walled carbon nanotube p-n junction diode device. The p-n junction is formed along a single nanotube by electrostatic doping using a pair of split gate electrodes. By biasing the two gates accordingly, the device can function either as a diode or as an ambipolar field-effect transistor. The diode current–voltage characteristics show forward conduction and reverse blocking characteristics, i.e., rectification. For low bias conditions, the characteristics follow the ideal diode equation with an ideality factor close to one.
Probability based models for estimation of wildfire risk
Authors: Preisler Haiganoush K. , Brillinger David R. , Burgan Robert E. , Benoit J. W.
Published: June 2004

We present a probability-based model for estimating fire risk. Risk is defined using three probabilities: the probability of fire occurrence; the conditional probability of a large fire given ignition; and the unconditional probability of a large fire. The model is based on grouped data at the 1 km2-day cell level. We fit a spatially and temporally explicit non-parametric logistic regression to the grouped data. The probability framework is particularly useful for assessing the utility of explanatory variables, such as fire weather and danger indices for predicting fire risk. The model may also be used to produce maps of predicted probabilities and to estimate the total number of expected fires, or large fires, in a given region and time period. As an example we use historic data from the State of Oregon to study the significance and the forms of relationships between some of the commonly used weather and danger variables on the probabilities of fire. We also produce maps of predicted probabilities for the State of Oregon. Graphs of monthly total numbers of fires are also produced for a small region in Oregon, as an example, and expected numbers are compared to actual numbers of fires for the period 1989–1996. The fits appear to be reasonable; however, the standard errors are large indicating the need for additional weather or topographic variables.
Multi-decadal variability of forest fire risk - eastern Australia
Authors: Verdon Danielle C. , Kiem Anthony S. , Franks Stewart W.
Published: June 2004

This study investigates the influence that the El Niño/Southern Oscillation (ENSO) and the Inter-decadal Pacific Oscillation (IPO) have on long term daily weather conditions pertinent to high forest fire danger in New South Wales, Australia. Using historical meteorological data for 22 weather stations to compute the daily value of McArthur’s Forest Fire Danger Index (FFDI), it is shown that a strong relationship exists between climate variability, on a range of time scales, and forest fire risk. An investigation into the influence of ENSO on fire risk demonstrates that the proportion of days with a high, or greater than high, fire danger rating is markedly increased during El Niño episodes. More importantly, this study also shows that the already significantly enhanced fire danger associated with El Niño events was even further increased during El Niño events that occurred when the IPO was negative. The potential to use simple indices of climate variability to predict forest fire risk is therefore demonstrated to be significant.
Impact of antecedent climate on fire regimes in coastal California
Authors: Keeley Jon E.
Published: June 2004

Severe fire weather is a major determinant of fire size in coastal California; however, it is unclear to what extent antecedent climate also controls fire activity. This study investigates the relationship between fire activity and climate in central coastal and southern California. Climate variables included the Palmer Drought Severity Index (PDSI), total monthly precipitation, mean monthly maximum temperature and the autumn and winter Southern Oscillation Indices (SOI). For both the central coast and the south coast regions there was no significant relationship between growing season PDSI, precipitation or temperature and number of fires. When examined by season, summer temperatures were positively correlated with number of fires in the central coast and autumn PDSI and precipitation were negatively correlated with fire occurrence in the south coast region. Area burned was not correlated with any current year climate variables in southern California although, in the central coast, drought during spring and autumn were correlated, but explained less than 10% of the variation in the area burned. Although there was a modest relationship between the Southern Oscillation Index (SOI) and local climate parameters, there was only a relatively weak relationship with fire activity. The importance of autumn foehn winds is illustrated by the observation that large fires occur most commonly during the autumn, regardless of PDSI. Antecedent climate, however, does appear to play some role in determining the length of the fire season on these landscape as PDSI is consistently related to the occurrence of large fires that occur before or after the autumn months.
Heating effects on water repellency in Australian eucalypt forest soils and their value in estimating wildfire soil temperatures
Authors: Doerr Stefan H. , Blake William H. , Shakesby Richard A. , Stagnitti Frank , Vuurens Saskia H. , Humphreys Geoff S. , Wallbrink Peter
Published: June 2004

Wildfires can induce or enhance soil water repellency under a range of vegetation communities. According to mainly USA-based laboratory studies, repellency is eliminated at a maximum soil temperature (T) of 280–400°C. Knowledge of T reached during a wildfire is important in evaluating post-fire soil physical properties, fertility and seedbed status. T is, however, notoriously difficult to ascertain retrospectively and often based on indicative observations with a large potential error. Soils under fire-prone Australian eucalypt forests tend to be water repellent when dry or moderately moist even if long unburnt. This study aims to quantify the temperature of water repellency destruction for Australian topsoil material sampled under three sites with contrasting eucalypt cover (Eucalyptus sieberi, E. ovata and E. baxteri). Soil water repellency was present prior to heating in all samples, increased during heating, but was abruptly eliminated at a specific T between 260 and 340°C. Elimination temperature varied somewhat between samples, but was found to be dependent on heating duration, with longest duration resulting in lowest elimination temperature. Results suggest that post-fire water repellency may be used as an aid in hindcasting soil temperature reached during the passage of a fire within repellency-prone environments.
Effects of heating on some soil physical properties related to its hydrological behaviour in two north-western Spanish soils
Authors: García-Corona R. , Benito E. , de Blas E. , Varela M. E.
Published: June 2004

Two forest soils rich in organic matter but differing in texture (sandy loam and silty loam) were heated under controlled laboratory conditions in order to examine the consequences of the heating effect that accompanies the passage of a fire on the physical properties of soil. Three samples of both soils were heated for 30 min in a muffle furnace at temperatures of 25, 170, 220, 380 and 460°C. At each temperature, the following parameters were determined: dry aggregate size distribution, water aggregate stability, total porosity, pore size distribution, water repellency and hydraulic conductivity. Heating the soils at 170 and 220°C caused no significant changes in aggregate size distribution or total porosity but increased water aggregate stability and the volume of pores 0.2–30 μm. Also, increased water repellency and strongly decreased the hydraulic conductivity. All parameters underwent much more dramatic changes at 380 and 460°C that can be ascribed to the combustion of organic matter. At such temperatures, water repellency was destroyed and the low hydraulic conductivity can be attributed to the aggregate breakdown observed under dry and wet conditions.
The effects of sarcoptic mange on the behaviour of wild common wombats (Vombatus ursinus)
Authors: Skerratt Lee F. , Skerratt John H. L. , Martin Roger , Handasyde Kathrine
Published: June 2004

Five free-living common wombats were captured, implanted with radio-transmitters, experimentally infected with 4000, 6000 or 8000 Sarcoptes scabiei var. wombati, then released and later recaptured for assessment of severity of infection, pathology and effect of sarcoptic mange on their behaviour. At the end of the study wombats were treated with ivermectin and amitraz to eradicate infection. Three wombats infected with 6000–8000 mites on their lateral surfaces developed mild sarcoptic mange within 14 weeks of infection. Two wombats infected with 4000 and 8000 mites, respectively, on lateral surfaces developed moderate sarcoptic mange within 14 weeks of infection. Free-living common wombats that were experimentally infected with S. scabiei travelled significantly further at night than wombats without mange; however, they used areas of similar size. They changed burrows for diurnal shelter as frequently as wombats without sarcoptic mange. They investigated and entered burrows during their nocturnal activities. There was no evidence of spread of infection from the five experimentally infected wombats to other wombats within the population by 18 weeks after introduction of S. scabiei.
Reproductive strategies of Pseudomys nanus and Pseudomys delicatulus (Rodentia : Muridae) from the monsoonal tropics of the Northern Territory
Authors: Taylor J. Mary , Calaby John H.
Published: June 2004

In the highly punctuated monsoonal climate of the Alligator Rivers area of Australia, Pseudomys nanus and Pseudomys delicatulus breed in the latter part of the monsoon season and can extend their breeding activity into spring. P. nanus may reproduce virtually year-round, presumably when environmental conditions are favourable. In both species, the predominance of young non-breeding adults and juveniles in the spring signals a new infusion of animals into the population and a large population turnover at the expense of older members. The young survivors of the seasonal transition from extremely dry to intensely wet conditions then become the primary contributors to the next major breeding episode. This study is based on histological evidence from the reproductive systems of both sexes.
Behavioural thermoregulation in butterflies: the interacting effects of body size and basking posture in Hypolimnas bolina (L.) (Lepidoptera : Nymphalidae)
Authors: Kemp Darrell J. , Krockenberger Andrew K.
Published: June 2004

The evolutionary significance of body size variation in male insects is often obscure. One way in which this parameter could affect reproductive success is via its relevance to thermoregulation. In this study we investigated the relevance of body size to heat exchange rates in a tropical nymphalid, the common eggfly (Hypolimnas bolina) (L.). Males of this territorial species elevate their body temperature above ambient levels via a series of basking postures coupled with strategic choice of perching microhabitat. In an experiment with dead butterfly models we found, as expected, heightened rates of heat exchange (heating and cooling rates) in smaller individuals. There was also a significant interaction between basking posture and body size, with smaller individuals exhibiting significantly greater variation in heating rate across all available basking postures. This suggests that smaller males would have greater control over their rate of basking heat gain (by having at their disposal a greater potential range of heating rates), but they would also radiate body heat at a higher rate than their larger conspecifics. Using 'grab and stab' techniques, we found no evidence that smaller individuals are closer to their putative thermal optimum under a range of ambient conditions in the field. However, a more substantive field program, incorporating a more precise characterisation of the ambient thermal environment, will be required to fully evaluate the thermal significance of body size variation in males of this territorial butterfly.
Mitochondrial-type assembly of FeS centers in the hydrogenosomes of the amitochondriate eukaryote
Trichomonas vaginalis
Authors: Sutak Robert , Dolezal Pavel , Fiumera Heather L. , Hrdy Ivan , Dancis Andrew , Delgadillo-Correa Maria , Johnson Patricia J. , Müller Miklós , Tachezy Jan
Published: June 2004

Mitochondria are the site of assembly of FeS centers of mitochondrial and cytosolic FeS proteins. Various microaerophilic or anaerobic unicellular eukaryotes lack typical mitochondria (“amitochondriate” protists). In some of these organisms, a metabolically different organelle, the hydrogenosome, is found, which is thought to derive from the same proteobacterial ancestor as mitochondria. Here, we show that hydrogenosomes of
Trichomonas vaginalis
, a human genitourinary parasite, contain a key enzyme of FeS center biosynthesis, cysteine desulfurase (TviscS-2), which is phylogenetically related to its mitochondrial homologs. Hydrogenosomes catalyze the enzymatic assembly and insertion of FeS centers into apoproteins, as shown by the reconstruction of the apoform of [2Fe-2S]ferredoxin and the incorporation of
35
S from labeled cysteine. Our results indicate that the biosynthesis of FeS proteins is performed by a homologous system in mitochondriate and amitochondriate eukaryotes and that this process is inherited from the proteobacterial ancestor of mitochondria.
Sample classification from protein mass spectrometry, by ‘peak probability contrasts’
Authors: Tibshirani Robert , Hastie Trevor , Narasimhan Balasubramanian , Soltys Scott , Shi Gongyi , Koong Albert , Le Quynh-Thu
Published: June 2004

Motivation: Early cancer detection has always been a major research focus in solid tumor oncology. Early tumor detection can theoretically result in lower stage tumors, more treatable diseases and ultimately higher cure rates with less treatment-related morbidities. Protein mass spectrometry is a potentially powerful tool for early cancer detection.

We propose a novel method for sample classification from protein mass spectrometry data. When applied to spectra from both diseased and healthy patients, the ‘peak probability contrast’ technique provides a list of all common peaks among the spectra, their statistical significance and their relative importance in discriminating between the two groups. We illustrate the method on matrix-assisted laser desorption and ionization mass spectrometry data from a study of ovarian cancers.

Results: Compared to other statistical approaches for class prediction, the peak probability contrast method performs as well or better than several methods that require the full spectra, rather than just labelled peaks. It is also much more interpretable biologically. The peak probability contrast method is a potentially useful tool for sample classification from protein mass spectrometry data.

Supplementary Information:  http://www.stat.stanford.edu/~tibs/ppc
Abstract Cauchy Problems for Quasi‐Linear Evolution Equations in the Sense of Hadamard
Authors: Tanaka Naoki
Published: June 2004

This paper is devoted to the well‐posedness of abstract Cauchy problems for quasi‐linear evolution equations. The notion of Hadamard well‐posedness is considered, and a new type of stability condition is introduced from the viewpoint of the theory of finite difference approximations. The result obtained here generalizes not only some results on abstract Cauchy problems closely related with the theory of integrated semigroups or regularized semigroups but also the Kato theorem on quasi‐linear evolution equations. An application to some quasi‐linear partial differential equation of weakly hyperbolic type is also given. 2000 Mathematics Subject Classification 34G20, 47J25 (primary), 47D60, 47D62 (secondary).
James bundles
Authors: Fenn Roger , Rourke Colin , Sanderson Brian
Published: June 2004

We study cubical sets without degeneracies, which we call □‐sets. These sets arise naturally in a number of settings and they have a beautiful intrinsic geometry; in particular a □‐set C has an infinite family of associated □‐sets Ji(C), for i = 1, 2, …, which we call James complexes. There are mock bundle projections pi: |Ji(C)| → |C| (which we call James bundles) defining classes in unstable cohomotopy which generalise the classical James–Hopf invariants of Ω(S2). The algebra of these classes mimics the algebra of the cohomotopy of Ω(S2) and the reduction to cohomology defines a sequence of natural characteristic classes for a □‐set. An associated map to BO leads to a generalised cohomology theory with geometric interpretation similar to that for Mahowald orientation. 2000 Mathematics Subject Classification 55N22, 55P44 (primary), 57R15, 57R20, 57R90 (secondary).
The Size of Plurisubharmonic Lemniscates in Terms of Hausdorff–Riesz Measures and Capacities
Authors: Zeriahi Ahmed
Published: June 2004

The main goal of this paper is to establish new uniform estimates on the size of sublevel sets of plurisubharmonic functions (called plurisubharmonic lemniscates) in terms of Hausdorff–Riesz measures and capacities of certain orders.

We first prove a new uniform version of Skoda's integrability theorem for a given class of plurisubharmonic functions in terms of Borel measures of Hausdorff–Riesz type of certain orders with a precise estimate of the integrability exponent in terms of Lelong numbers of the class and the order of the measures.

Then we present several applications of this result. We first deduce uniform estimates on the size of plurisubharmonic lemniscates associated to functions from some important classes of plurisubharmonic functions in terms of Hausdorff–Riesz measures.

We also derive a new comparison inequality between certain Hausdorff–Riesz capacities and the pluricomplex logarithmic capacity for borelean sets of a fixed bounded domain in Cn or more generally in an affine algebraic manifold.

Furthermore, using results from classical potential theory, we finally deduce from this comparison inequality new estimates of the size of polynomial lemniscates in terms of Hausdorff contents in the spirit of the famous lemma of H. Cartan. 2000 Mathematics Subject Classification 31C10, 31C15, 32F05, 32F99, 32U05, 32U99.
Calderón Projector for the Hessian of the Perturbed Chern–Simons Function on a 3‐Manifold with Boundary
Authors: Himpel Benjamin , Kirk Paul , Lesch Matthias
Published: June 2004

The existence and continuity for the Calderón projector of the perturbed odd signature operator on a 3‐manifold is established. As an application we give a new proof of a result of Taubes relating the modulo 2 spectral flow of a family of operators on a homology 3‐sphere with the difference in local intersection numbers of the character varieties coming from a Heegard decomposition. 2000 Mathematics Subject Classification 57M27 (primary), 58J32 (secondary).
Exercise training increases intramyocellular lipid and oxidative capacity in older adults
Authors: Pruchnic Ryan , Katsiaras Andreas , He Jing , Kelley David E. , Winters Carena , Goodpaster Bret H.
Published: June 2004

Intramyocellular lipid (IMCL) has been associated with insulin resistance. However, an association between IMCL and insulin resistance might be modulated by oxidative capacity in skeletal muscle. We examined the hypothesis that 12 wk of exercise training would increase both IMCL and the oxidative capacity of skeletal muscle in older (67.3 ± 0.7 yr), previously sedentary subjects ( n = 13; 5 men and 8 women). Maximal aerobic capacity (V̇o2 max) increased from 1.65 ± 0.20 to 1.85 ± 0.14 l/min ( P < 0.05), and systemic fat oxidation induced by 1 h of cycle exercise at 45% of V̇o2 maxincreased ( P < 0.05) from 15.03 ± 40 to 19.29 ± 0.80 (μmol·min−1·kg fat-free mass−1). IMCL, determined by quantitative histological staining in vastus lateralis biopsies, increased ( P < 0.05) from 22.9 ± 1.9 to 25.9 ± 2.6 arbitrary units (AU). The oxidative capacity of muscle, determined by succinate dehydrogenase staining intensity, significantly increased ( P < 0.05) from 75.2 ± 5.2 to 83.9 ± 3.6 AU. The percentage of type I fibers significantly increased ( P < 0.05) from 35.4 ± 2.1 to 40.1 ± 2.3%. In conclusion, exercise training increases IMCL in older persons in parallel with an enhanced capacity for fat oxidation.
Insulin infusion induces endothelin-1-dependent hypertension in rats
Authors: Juan Chi-Chang , Shen Yi-Wen , Chien Yueh , Lin Yen-Jie , Chang Shau-Feng , Ho Low-Tone
Published: June 2004

We previously showed that chronic insulin infusion induces insulin resistance, hyperendothelinemia, and hypertension in rats (C. C. Juan, V. S. Fang, C. F. Kwok, J. C. Perng, Y. C. Chou, and L. T. Ho. Metabolism 48: 465–471, 1999). Endothelin-1 (ET-1), a potent vasoconstrictor, is suggested to play an important role in maintaining vascular tone and regulating blood pressure, and insulin increases ET-1 production in vivo and in vitro. In the present study, BQ-610, a selective endothelin A receptor antagonist, was used to examine the role of ET-1 in insulin-induced hypertension in rats. BQ-610 (0.7 mg/ml; 0.5 ml/kg body wt) or normal saline was given intraperitoneally two times daily for 25 days to groups of rats infused with either saline or insulin (2 U/day via sc-implanted osmotic pumps), and changes in plasma levels of insulin, glucose, and ET-1 and the systolic blood pressure were measured over the experimental period, whereas changes in insulin sensitivity were examined at the end of the experimental period. Plasma insulin and ET-1 levels were measured by RIA, plasma glucose levels using a glucose analyzer, systolic blood pressure by the tail-cuff method, and insulin sensitivity by an oral glucose tolerance test. Our studies showed that insulin infusion caused sustained hyperinsulinemia in both saline- and BQ-610-injected rats over the infusion period. After pump implantation (2 wk), the systolic blood pressure was significantly higher in insulin-infused rats than in saline-infused rats in the saline-injected group (133 ± 3.1 vs. 113 ± 1.1 mmHg, P < 0.05) but not in the BQ-610-injected group (117 ± 1.2 vs. 117 ± 1.8 mmHg). Plasma ET-1 levels in both sets of insulin-infused rats were higher than in saline-infused controls (2.5 ± 0.6 and 2.5 ± 0.8 vs. 1.8 ± 0.4 and 1.7 ± 0.3 pmol/l, P < 0.05). Oral glucose tolerance tests showed that BQ-610 treatment did not prevent the insulin resistance caused by chronic insulin infusion. No significant changes were found in insulin sensitivity and blood pressure in saline-infused rats treated with BQ-610. In a separate experiment, insulin infusion induced the increase in arterial ET-1 content, hypertension, and subsequent plasma ET-1 elevation in rats. These results suggest that, in the insulin infusion rat model, ET-1 plays a mediating role in the development of hypertension, but not of insulin resistance.
Adrenergic regulation of salt and fluid secretion in human medullary collecting duct cells
Authors: Wallace Darren P. , Reif Gail , Hedge Anne-Marie , Thrasher J. Brantley , Pietrow Paul
Published: June 2004

Transepithelial salt and fluid secretion mediated by cAMP in initial inner medullary collecting ducts (IMCDi) may be important for making final adjustments to urine composition. We examined in primary cultures of human IMCDicells the effects of adrenergic receptor (AR) agonists and antagonists on intracellular cAMP levels, short-circuit current ( ISC), and fluid secretion. Epinephrine (1 μM), norepinephrine (1 μM), and isoproterenol (10 nM) individually increased intracellular cAMP levels 57-, 2-, and 25-fold, respectively, and stimulated ISC3.3-, 2.9-, and 3.4-fold, respectively. β-AR activation increased net fluid secretion by cultured human IMCDicell monolayers from 0.09 ± 0.04 to 0.26 ± 0.05 μl·h−1·cm−2and freshly isolated rat IMCDifrom 0.02 ± 0.01 to 0.09 ± 0.02 nl·h−1·mm−1. In monolayers, these effects were eliminated by blocking β2-AR, but not β1-AR. Activation of α2-AR with guanabenz inhibited isoproterenol-induced ISCby 37% in human IMCDimonolayers and fluid secretion by 91% in rat IMCDi. Immunohistochemistry of human medullary tissue sections revealed greater expression of β2-AR than β1-AR; β2-AR was localized to the basolateral membranes of human IMCDi. Immunoblots identified α2A-AR and α2B-AR in cultured human IMCDicell monolayers. We conclude that 1) catecholamines stimulate cAMP-dependent anion and fluid secretion by IMCDicells primarily through β2-AR activation and 2) α2-AR activation attenuates cAMP-dependent anion secretion.
Impact of commensal microbiota on murine gastrointestinal tract gene ontologies
Authors: Mutch David M. , Simmering Rainer , Donnicola Dominique , Fotopoulos Grigorios , Holzwarth James A. , Williamson Gary , Corthésy-Theulaz Irène
Published: June 2004

The gastrointestinal tract (GIT) of eukaryotes is colonized by a vast number of bacteria, where the commensal microbiota play an important role in defining the healthy gut. To investigate the influence of commensal bacteria on multiple regions of the host GIT transcriptome, the gene expression profiles of the corpus, jejunum, descending colon, and rectum of conventional ( n = 3) and germ-free mice ( n = 3) were examined using the Affymetrix Mu74Av2 GeneChip. Differentially regulated genes were identified using the global error assessment model, and a novel method of Gene Ontology (GO) clustering was used to identify significantly modulated biological functions. The microbiota modify the greatest number of genes in the jejunum (267 genes with an α < 0.001) and the fewest in the rectum (137 genes with an α < 0.001). Clustering genes by GO biological process and molecular function annotations revealed that, despite the large number of differentially regulated genes, the residential microbiota most significantly modified genes involved in such biological processes as immune function and water transport all along the length of the mouse GIT. Additionally, region-specific communication between the host and microbiota were identified in the corpus and jejunum, where tissue kallikrein and apoptosis regulator activities were modulated, respectively. These findings identify important interactions between the microbiota and the mouse gut tissue transcriptome and, furthermore, suggest that interactions between the microbial population and host GIT are implicated in the coordination of region-specific functions.
Fetichism and Proselytism
Authors: Boulaga Fabien Eboussi
Published: June 2004

The author gives a reaction to the criticism put forward to his book Christianity without Fetishes. He tries to show that his book is an effort in order to reduce the dangers of Christian expression, according to positive rules that describe qualities according to the principle of reductionism or exclusion. The book rejects the easy assimilation by change or by pure and simple reduction to instruments alone. In the end Boulaga asserts that the criticism of mission is the necessary precondition for all criticism.