bluuebunny/crossref_metadata_2025 huggingface dataset:
PVD‐Beschichtungen für trockenlaufende Hybridwälzlager
Authors: Bobzin K. , Gold Peter W. , Nickel R. , Loos J. , Bagcivan N. , Krämer A. , Plogmann M.
Published: March 2007

PVD‐Beschichtungen können die Eigenschaften trockenlaufender Hybridwälzlager verbessern. So kann der Verschleiß, aber auch das Reibmoment mit ihrer Hilfe herabgesetzt werden. Um dies zu erreichen, wurden PVD‐Schichten im Hinblick auf die auftretenden Belastungen weiterentwickelt. Untersuchungen mit Hilfe des standardisierten FE8‐Wälzlagerprüfstands dienten zum Nachweis des Potentials der PVD‐Beschichtungen für den Trockenlauf. Die Ergebnisse dieser Untersuchung wiederum flossen in die Schichtentwicklung ein.
Actinobacillus actinomycetemcomitans adheres to human gingival fibroblasts and modifies cytoskeletal organization
Authors: Gutiérrez‐Venegas Gloria , Kawasaki‐Cárdenas Perla , Garcés Carla Portillo , Román‐Alvárez Patricia , Barajas‐Torres Carolina , Contreras‐Marmolejo Luis Arturo
Published: March 2007

Adherence of Actinobacillus actinomycetemcomitans to human gingival fibroblast cells induces cytoskeletal reorganization. A. actinomycetemcomitans is considered a pathogenic bacteria involved in localized aggressive periodontitis. Studies with epithelial cells have shown an adherent capacity of bacteria that is increased under anaerobic conditions. For adherence to take place, there is a need for interaction between extracellular vesicles and bacterial fimbriae. However, molecular events associated with the adherence process are still unknown. The aim of this study was to investigate whether A. actinomycetemcomitans adherence to human gingival fibroblasts promotes cytoskeletal reorganization. Adherence was determined with light microscopy and scanning electron microscopy. For F‐actin visualization, cells were treated with fluorescein—isothiocyanate—phalloidin and samples were examined with epifluorescence optics. Fluorescent was recorded on Kodak T‐Max 400 film.

We showed that A. actinomycetemcomitans adheres to human gingival fibroblast primary cultures, this property stimulating an increase in the intracellular calcium levels. In human gingival fibroblast primary cultures, we observed that maximal A. actinomycetemcomitans adherence took place 1.5 h after culture infection occurred and remained for 6 h. The adherence was associated with morphologic alterations and an increased in the intracellular calcium levels. These experiments suggest that A. actinomycetemcomitans adherence cause morphological alterations, induce actin stress fibers and recruitment of intracellular calcium levels.
Lack of a time‐dependent effect of melatonin on radiation‐induced apoptosis in cultured rat lymphocytes
Authors: Yurtcu Erkan , Guney Yildiz , Ergun Mehmet Ali , Guney H. Zafer , Uluoglu Canan , Hicsonmez Ayse , Yucel Berna , Ozbey Gul , Zengil Hakan
Published: March 2007

Ionizing radiation is widely used for the treatment of solid tumors and it is thought to act by directly targeting tumor clonogens, also known as stem cells. Apoptosis is a genetically programmed mechanism of cell death often characterized by internucleosomal DNA cleavage. Although it has been previously shown that lymphocytes readily undergo apoptosis in patients receiving anticancer drugs or treatment with ionizing radiation, this is the first study to investigate the influence of radiotherapy and melatonin on apoptosis in rat lymphocytes at two different times of the day. Melatonin, a free radical scavenger, is an endogenous neurohormone predominantly synthesized in and secreted by the pineal gland. It has been shown that melatonin inhibits apoptosis in normal cells but it increases the rate of apoptosis in various cancer cells. Therefore, in the present study, the effect of melatonin on apoptosis in cultured lymphocytes was studied after total body irradiation (TBI) was given to rats in the morning (1 HALO) or evening (13 HALO) with morphological and DNA fragmentation analysis. Two‐way analysis of variance (ANOVA) revealed that radiation increased the rate of apoptosis in rat lymphocytes after TBI, and melatonin treatment did not reduce the rate of apoptosis after TBI at either time point. We conclude that the lack of an effect of melatonin on the apoptosis rate in rat lymphocytes might be due to the dose‐dependent effect of melatonin, the time course of apoptosis investigated, or the cell type in which apoptosis was examined.
Fetal electrocardiogram ST‐segment analysis and prediction of neonatal acidosis
Authors: Vayssiere C. , Haberstich R. , Sebahoun V. , David E. , Roth E. , Langer B.
Published: March 2007

Objective: To determine the diagnostic value of fetal ST‐segment analysis (STAN) in predicting neonatal acidosis. Methods: The STAN S21® was used to monitor singleton fetuses in labor with abnormal FHR. Physicians later reviewed tracings to identify any ST events dictating intervention. Outcome measures were umbilical artery pH ≤ 7.15 and pH ≤ 7.05 at birth. The sensitivity, specificity, PPV, and NPV of a significant ST event to predict both outcomes were calculated. Results: Analysis included 411 women. Sensitivity of a significant ST event for screening pH ≤ 7.15 (21.9%) was 38% (41/108), specificity 83% (252/303), PPV 45% (41/92) and NPV 79% (252/319), and for pH ≤ 7.05, it was (3.4%), 62.5% (10/16), 79% (313/395), 11% (10/92), and 98% (313/319), respectively. Conclusion: In a population with abnormal FHR in labor, STAN sensitivity is moderate (almost 40%) for predicting pH ≤ 7.15 and better (almost 60%) for more severe acidosis (pH ≤ 7.05).
Cobalamin, folate and inorganic phosphate abnormalities in ill cats
Authors: Reed Nicola , Gunn-Moore Danièlle , Simpson Kerry
Published: March 2007

Hypocobalaminaemia in cats has previously been identified, but the incidence reported has varied, and the frequency of folate deficiency is unknown. The aims of this study were to evaluate the incidence of low cobalamin and folate levels in a population of cats that were suffering predominantly from diseases of the alimentary tract (including the liver and pancreas) and to ascertain whether severity of disease (as assessed by bodyweight and body condition score (BCS)) related to degree of deficiency. The study population comprised 103 cats, of which 16.5% had low cobalamin levels and 38.8% had low folate levels. A serendipitous finding was inorganic phosphate levels below the reference range in 48% of the cases. Significant associations were found between subnormal cobalamin levels and median BCS ( P=0.049); combined low folate and low cobalamin and bodyweight ( P=0.002), BCS ( P=0.024) and inorganic phosphate levels ( P=0.003). The finding of low levels of folate and cobalamin in clinical cases suggests that supplementation may be indicated more frequently than is currently recognised.
Feline diabetes mellitus in the UK: The prevalence within an insured cat population and a questionnaire-based putative risk factor analysis
Authors: McCann Theresa M , Simpson Kerry E , Shaw Darren J , Butt Jennifer A , Gunn-Moore Danielle A.
Published: March 2007

Prevalence and risk factors for the development of diabetes mellitus (DM) in cats in the United Kingdom have not previously been reported. The prevalence of DM was evaluated in a large insured population and was found to be 1 in 230 cats. In this insured cat population Burmese cats were 3.7 times more likely to develop DM than non-pedigree cats. A convenience-sampling questionnaire-based study was used in order to identify putative risk factors for the development of DM. The univariate risk factor analysis identified being male, neutered, inactive, weighing ≥5 kg and having a history of corticosteroid treatment as significant risk factors for the development of DM in these cats. In addition, male cats treated with megestrol acetate had a significantly increased risk of developing DM compared to females. In contrast, there was no difference in DM occurrence between male and female Burmese cats. A multivariate classification tree-based model on the questionnaire data looking for interactions between risk factors, identified gender as the most important overall risk factor for the development of DM with low physical activity being the next most important risk factor for female cats and breed the next most important for male cats.
EFFECTIVE FLOWERING TIME VARIATIONS IN UPLAND COTTON (GOSSYPIUM HIRSUTUM) AT DIFFERENT PLANTING DATES AND STAND DENSITIES IN BENIN
Authors: SEKLOKA EMMANUEL , HAU BERNARD , GOZÉ ERIC , LEWICKI SYLVIE , THOMAS GRÉGOIRE , LANÇON JACQUES
Published: March 2007

Effective flowering time in Gossypium hirsutum cotton plants was studied with the aim of enhancing decision making on the best varieties to plant according to the planting date under rainfed cropping conditions. Trials were conducted at two sites in a cotton-growing area of Benin in 2002 and 2003. A split-split plot design with three replicates was used to compare 10 cotton varieties, with different growth cycle lengths and morphology, at three stand densities (42 000, 125 000, 167 000 plants ha−1) and two planting dates (standard planting in June and late planting). The flowering period was characterized by the mean first flower opening date (FF), which is an indicator of flowering earliness, and by the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1). Effective flowering time (EFT) was calculated as the difference between LFP1 and FF. EFTs differed markedly in the 10 cotton varieties tested and this parameter could not be predicted on the basis of flowering earliness. Late planting and high planting rates delayed first-flower opening, accelerated last-boll development and reduced the effective flowering time. This latter factor should be taken into account in cotton breeding programmes so that varieties adapted to local rainfall constraints can be recommended to growers while also enhancing crop management sequences.
A SIMPLE METHOD FOR ESTIMATING THE END OF EFFECTIVE FLOWERING IN UPLAND COTTON (GOSSYPIUM HIRSUTUM)
Authors: SEKLOKA EMMANUEL , LANÇON JACQUES , HAU BERNARD , GOZÉ ERIC , LEWICKI SYLVIE , THOMAS GRÉGOIRE
Published: March 2007

In cotton (Gossypium hirsutum), it is hard to determine the exact date when reproductive growth ceases on the basis of field observations, as compared to more visible factors such as the onset of flowering or boll opening. It is, however, essential to characterize the growth cycle in order to determine what varieties are suitable for planting in different climatic and local cropping conditions. We estimated the end of the effective flowering period on the basis of the opening date of the last flower giving rise to a first-position boll on fruiting branches (LFP1), and propose a simple method for estimating this date. This study, conducted in 2002 and 2003 at Okpara, Benin, involved a comparison of six cotton varieties planted at two different dates (June and July). Plants were monitored to determine the dates when flowers opened at each position on fruiting branches. The LFP1 indicator made a clear distinction between varieties. This highly heritable trait, which was found to be closely correlated with other earliness criteria, could be used to characterize the length of the growth cycle in cotton varieties.
INFLUENCE OF RESOURCE QUALITY OF ORGANIC INPUTS ON RICE-BARLEY DRYLAND AGRO-ECOSYSTEM: VARIATIONS IN BIOLOGICAL PRODUCTIVITY, GRAIN YIELD AND EFFICIENCY OF NITROGEN USE
Authors: SINGH SONU , GHOSHAL NANDITA , SINGH K. P.
Published: March 2007

A two-year study was undertaken in a tropical dryland agro-ecosystem to evaluate the effect of the application of soil amendments with contrasting chemical natures on crop productivity, grain yield, N-uptake and N-use efficiencies. The treatments involved the addition of equivalent amounts of N (80 kg N ha−1) through chemical fertilizer and three organic inputs at the beginning of the annual cycle: Sesbania aculeata shoots (high quality, C/N 16), wheat straw (low quality, C/N 82) and Sesbania+wheat straw (high and low quality combined, C/N 47), together with a control treatment. Test crops consisted of an annual sequence of rice and barley, sown in the rainy and winter seasons, respectively. Fertilizer and Sesbania inputs resulted in higher total net productivity (TNP) for the rice crop (47 % and 32 % increases over the control, respectively) than the combined (+28 %) and wheat straw treatments (+10 %). During the succeeding barley crop, maximum TNP was recorded in the Sesbania+wheat straw treatment (+52 %), followed by wheat straw (+43 %), fertilizer (+19 %) and Sesbania (+17 %). The TNP and grain yields of both crops added together were higher in Sesbania+wheat straw and fertilizer treatments compared to a single applications of either Sesbania or wheat straw. The Sesbania+wheat straw and fertilizer treatments resulted in more efficient utilization of N compared to the other treatments. Crop roots played a pivotal role in N-recovery from the soil and their N concentrations differed significantly (p < 0.05) due to the application of soil amendments. Across different treatments, crop root biomass was strongly correlated with crop N-uptake (r = 0.81, n = 10, p < 0.05), recovery efficiency (r = 0.81, n = 8, p < 0.05) and agronomic efficiency (r = 0.81, n = 8, p < 0.05). It is suggested that the combined application of high and low quality resources modulated N release, resulting in relatively higher productivity through the annual cropping cycle. Such combined inputs may prove useful in developing low input, environment friendly soil management practices in tropical dryland agro-ecosystems.
POSSIBILITY OF EARLY COMMENCEMENT OF TAPPING IN RUBBER (HEVEA BRASILIENSIS) USING DIFFERENT GENOTYPES AND TAPPING SYSTEMS
Authors: GUNASEKARA H. K. L. K. , NUGAWELA E. A. , DE COSTA W. A. J. M. , ATTANAYAKE D. P. S. T. G.
Published: March 2007

The feasibility of commencing tapping (‘opening’) of rubber trees for latex extraction at a lower stem girth (40 and 45 cm) than the currently recommended 50 cm was investigated in three different genotypes. The possibility of combining early opening with low frequency tapping and yield stimulation using Ethrel (LFT + E) was also examined. One of the genotypes tested, RRIC 121, gave a higher dry rubber yield, both per tapping and cumulatively over a given period, when opened at 40 cm than at 50 cm. Of the other two genotypes, one (RRISL 211) showed a clear reduction in yield with early opening, while the other (RRIC 102) did not show a significant yield response. Among the three genotypes tested, RRIC 121 showed the minimum depression in trunk girth increment. Analysis of yield components showed that the response of a given genotype to early opening and LFT + E is determined by the interaction between latex volume per tapping and dry rubber content (DRC), which were negatively correlated. RRIC 121 had a significantly greater DRC, which enabled it to maintain a higher dry rubber yield under early opening and LFT + E despite producing a lower latex volume than both the other genotypes. In contrast, despite producing a substantially greater latex volume than the other two genotypes, RRISL 211 did not produce a higher dry rubber yield because of its lower DRC. The higher DRC was also responsible for the greater response of RRIC 121 to yield stimulation with Ethrel, which reduced the plugging index and increased the initial latex flow rate. Early commencement of tapping in combination with LFT + E is therefore possible in rubber when amenable genotypes are selected, offering the potential of improving the economics of rubber production, especially for smallholders, in West Asia.
SMALL-SCALE DAIRY FARMING IN THE HIGHLANDS OF CENTRAL MEXICO: TECHNICAL, ECONOMIC AND SOCIAL ASPECTS AND THEIR IMPACT ON POVERTY
Authors: ESPINOZA-ORTEGA A. , ESPINOSA-AYALA E. , BASTIDA-LÓPEZ J. , CASTAÑEDA-MARTÍNEZ T. , ARRIAGA-JORDÁN C. M.
Published: March 2007

Small-scale dairy farming has been suggested as a rural development option for Mexican campesino communities. However, there is a lack of information on how dairy farming systems operate. The objective of this paper is to analyse the social, productive and economic characteristics of small-scale dairy production systems in the central highlands in the northwest of the State of Mexico. These three characteristics were analysed on 69 farms using factor and cluster analysis. Five factors accounted for 68% of cumulative variance. Cluster analysis yielded three well-defined groups. A Kruskal–Wallis test was performed on the arable land area and the number of animals, and analysis of variance for milk yield. Economic analysis was undertaken using activity budgets. Results showed the relationships between scale and management methods and their effects on the income for the family. Families in only one of the three groups receive incomes from dairying that were above all Mexican poverty indices. This outcome is explained by the intensification in the management of their herds, which is reflected in higher milk yields, higher incomes and better access to government support schemes. Enhancement of milk production in the area studied needs differential policies which take in to account differences between the groups identified.
The Catholic Church and the English Civil War: The Case of Thomas White
Authors: TUTINO STEFANIA
Published: March 2007

Thomas White alias Blacklo, an English Catholic priest, natural philosopher and theologian, was the leader of a small group of Catholics, known as ‘Blackloists’, who in the 1640s and 1650s wrote in support of Oliver Cromwell. This article seeks to explain the ecclesiological, theological and political arguments put forward by White and his followers in order to justify their approach to the Independents and later to the Lord Protector. After putting into context and interpreting some of the issues elaborated in White's circle, the reaction of the Holy See to Thomas White and to his political and theological positions is examined. While contemporary historiography seems to agree that the majority of English Catholics were on the king's side during the civil war, the evidence that emerges from White's case shows that the Roman hierarchy was of a different opinion.
Heirs of Richard Baxter? The Society of Free Catholics, 1914–1928
Authors: KAYE ELAINE
Published: March 2007

The Society of Free Catholics was founded in 1914 by a small group of Unitarian ministers, who, inspired by Richard Baxter, James Martineau, F. D. Maurice and the Catholic Modernists, sought to combine historic Catholic sacramental and devotional practice with theological freedom, and to unite all Christians in a Free Christian Church. The members included Anglicans, Nonconformists and a few Roman Catholics. The two main leaders of the society were J. M. Lloyd Thomas of the old Meeting, Birmingham, and W. E. Orchard of the King's Weigh House, London. Their chief legacy was a series of prayer books for public worship.
On the formation of geophysical and planetary zonal flows by near-resonant wave interactions
Authors: LEE YOUNGSUK , SMITH LESLIE M.
Published: March 2007

Numerical simulations on a β-plane are used to further understand the formation of zonal flows from small-scale fluctuations. The dynamics of ‘reduced models’ are computed by restricting the nonlinear term to include a subset of triad interactions in Fourier space. Reduced models of near-resonant triads are considered, as well as the complement set of non-resonant triads. At moderately small values of the Rhines number, near-resonant triad interactions are shown to be responsible for the generation of large-scale zonal flows from small-scale random forcing. Without large-scale drag, both the full system and the reduced model of near resonances produce asymmetry between eastward and westward jets, in favour of stronger westward jets. When large-scale drag is included, the long-time asymmetry is reversed in the full system, with eastward jets that are thinner and stronger than westward jets. Then the reduced model of near resonances exhibits a weaker asymmetry, but there are nevertheless more eastward jets stronger than a threshold value.
Cavitation microstreaming patterns in single and multiple bubble systems
Authors: THO PAUL , MANASSEH RICHARD , OOI ANDREW
Published: March 2007

Cavitation microstreaming is a well-known phenomenon; however, few flow visualizations or measurements of the velocity fields have been conducted. In this paper micro-PIV (particle image velocimetry) measurements and streak photography were used to study the flow field around a single and two oscillating bubbles resting on a solid boundary. The mode of oscillation of the bubble was also measured in terms of the variation in the radius of the bubble and the movement of the bubble's centroid so that the streaming flow field could be accurately related to the bubble's oscillatory motion. The mode of oscillation was found to vary primarily with the applied acoustic frequency. Several modes of oscillation were investigated, including translating modes where the bubble's centroid moves along either a single axis, an elliptical orbit or a circular orbit. The flow field resulting from these oscillation modes contains closed streamlines representing vortical regions in the vicinity of the bubble. The translating modes were observed to occur in sequential order with the acoustic excitation frequency, changing from a translation along a single axis, to an elliptical orbit and finally to a circular orbit, or vice versa. Following this sequence, there is a corresponding transformation of the streaming pattern from a symmetrical flow structure containing four vortices to a circular vortex centred on the bubble. Despite some inconsistencies, there is general agreement between these streaming patterns and those found in existing theoretical models. Volume and shape mode oscillations of single bubbles as well as several different cases of multiple bubbles simultaneously oscillating with the same frequency and phase were also investigated and show a rich variety of streaming patterns.
Scattering of surface gravity waves by bottom topography with a current
Authors: ARDHUIN FABRICE , MAGNE RUDY
Published: March 2007

A theory is presented that describes the scattering of random surface gravity waves by small-amplitude topography, with horizontal scales of the order of the wavelength, in the presence of an irrotational and almost uniform current. A perturbation expansion of the wave action to order η2 yields an evolution equation for the wave action spectrum, where η = max(h)/H is the small-scale bottom amplitude normalized by the mean water depth. Spectral wave evolution is proportional to the bottom elevation variance at the resonant wavenumbers, representing a Bragg scattering approximation. With a current, scattering results from a direct effect of the bottom topography, and an indirect effect of the bottom through the modulations of the surface current and mean surface elevation. For Froude numbers of the order of 0.6 or less, the bottom topography effects dominate. For all Froude numbers, the reflection coefficients for the wave amplitudes that are inferred from the wave action source term are asymptotically identical, as η goes to zero, to previous theoretical results for monochromatic waves propagating in one dimension over sinusoidal bars. In particular, the frequency of the most reflected wave components is shifted by the current, and wave action conservation results in amplified reflected wave energies for following currents. Application of the theory to waves over current-generated sandwaves suggests that forward scattering can be significant, resulting in a broadening of the directional wave spectrum, while back-scattering should be generally weaker.
Scaling of the wall-normal turbulence component in high-Reynolds-number pipe flow
Authors: ZHAO RONGRONG , SMITS ALEXANDER J.
Published: March 2007

Streamwise and wall-normal turbulence components are obtained in fully developed turbulent pipe over a Reynolds number range from 1.1 × 105to 9.8 × 106. The streamwise intensity data are consistent with previous measurements in the same facility. For the wall-normal turbulence intensity, a constant region inv'r.m.s.is found for the region 200 ≤ y+≤ 0.1R+for Reynolds numbers up to 1.0 × 106. An increase inv'r.m.s.is observed below abouty+∼ 100, although additional measurements will be required to establish its generality. The wall-normal spectra collapse in the energy-containing region with inner scaling, but for the low-wavenumber region ay/Rdependence is observed, which also indicates a continuing influence from the outer flow on the near-wall motions.
Integral force acting on a body due to local flow structures
Authors: WU J.-Z. , LU X.-Y. , ZHUANG L.-X.
Published: March 2007

The forces exerted on a body moving through a fluid depend strongly on the local dynamic processes and structures generated by the body motion, such as flow separation, vortices, etc. A detailed and quantitative understanding of the effects of these processes and structures on the instantaneous overall force characteristics is of fundamental significance, and may improve our capabilities for flow analysis and control. In the present study, some unconventional force expressions based on ‘derivative-moment transformations’, which can have a rich variety of forms for the same flow field, are used to provide better insight into local dynamics. In particular, we apply jointly three alternative unconventional force expressions to analyse two numerical solutions of unsteady and viscous circular-cylinder flows. The results confirm the exactness of the expressions and, more importantly, provide a unified understanding of the specific influence on the force of each individual flow structure at its different evolution stages.
Langmuir turbulence in shallow water. Part 1. Observations
Authors: GARGETT ANN E. , WELLS JUDITH R.
Published: March 2007

During extended deployment at an ocean observatory off the coast of New Jersey, a bottom-mounted five-beam acoustic Doppler current profiler measured large-scale velocity structures that we interpret as Langmuir circulations filling the entire water column. These circulations are the large-eddy structures of wind-wave-driven turbulent flows that occur episodically when a shallow water column experiences prolonged strong wind forcing. Many observational characteristics agree with former descriptions of Langmuir circulations in deep water. The three-dimensional velocity field reveals quasi-organized structures consisting of pairs of surface-intensified counter-rotating vortices, aligned approximately downwind. Maximum downward velocities are stronger than upward velocities, and the downwelling region of each cell, defined as a pair of vortices, is narrower than the upwelling region. Maximum downward vertical velocity occurs at or above mid-depth, and scales approximately with wind speed. The estimated crosswind scale of cells is roughly 3–6 times their vertical scale, set under these conditions by water depth. The long axis of the cells appears to lie at an angle ∼10°–20° to the right of the wind. A major difference from deep-water observations is strong near-bottom intensification of the downwind ‘jets’ found typically centred over downwelling regions. Accessible observational features such as cell morphology and profiles of mean velocities, turbulent velocity variances, and shear stress components are compared with the results of associated large-eddy simulations (reported in Part 2) of shallow water flows driven by surface stress and the Craik–Leibovich vortex forcing generally used to represent generation of Langmuir cells. A particularly sensitive diagnostic for identification of Langmuir circulations as the energy-containing eddies of the turbulent flow is the depth trajectory of invariants of the turbulent stress tensor, plotted in the Lumley ‘triangle’ corresponding to realizable turbulent flows. When Langmuir structures are present in the observations, the Lumley map is distinctly different from that of surface-stress-driven Couette flow, again in agreement with the large-eddy simulations (LES). Unlike the LES, observed velocity fields contain two distinct and significant scales of variability, documented by wavelet analysis of observational records of vertical velocity. Variability with periods of many minutes is that expected from Langmuir cells drifting past the instrument at the slowly time-varying crosswind velocity. Shorter period variability, of the order of 1–2 min, has roughly the observed periodicity of surface wave groups, suggesting a connection with the wave groups themselves and/or the wave breaking associated with them in high wind conditions.
On impulsively generated inviscid axisymmetric surface jets, waves and drops
Authors: TJAN K. K. , PHILLIPS W. R. C.
Published: March 2007

The evolution of an unbounded inviscid free surface subjected to a velocity potential of Gaussian form and also to the influence of inertial, interfacial and gravitational forces is considered. This construct was motivated by the occurrence of lung haemorrhage resulting from ultrasonic imaging and pursues the notion that bursts of ultrasound act to expel droplets that puncture the soft air-filled sacs in the lung plural surface, allowing them to fill with blood. The tissue adjacent to the sacs is modelled as a liquid and the air–tissue interface in the sacs as a free surface. The evolution of the free surface is described by a boundary-integral formulation and, since the free surface evolves slowly relative to the bursts of ultrasound, they are realized as an impulse at the free surface, represented by the velocity potential. As the free surface evolves, it is seen to form axisymmetric surface jets, waves or droplets, depending upon the levels of gravity and surface tension. Moreover the droplets may be spherical and ejected away from the surface or an inverted tear shape and fall back to the surface. These conclusions are expressed in a phase diagram of inverse Froude number Fr−1 versus inverse Weber number We−1. Specifically, while axisymmetric surface jets form in the absence of surface tension and gravity, gravity acts to bound their height, rendering them waves, although instability overrides the calculation prior to its reaching that bound. Surface tension acts to suppress the instability (provided that We−1 > 0.045) and to form drops; if sufficiently strong it can also damp the evolving wave, causing it to collapse. The pinchoff which effects spherical drops is of power-law type with exponent 2/3, and the universal constant that relates the necking radius to the time from pinchoff, thereby realizing a finite-time singularity, has the value ${\mathfrak{K}} \,{=}\, 0.45 \pm 0.025$. Finally, drops can occur once the mechanical index, a dimensional measure used in ultrasonography, exceeds 0.5.
Double-diffusive instabilities of autocatalytic chemical fronts
Authors: D'HERNONCOURT J. , DE WIT A. , ZEBIB A.
Published: March 2007

Convective instabilities of an autocatalytic propagating chemical front in a porous medium are studied. The front creates temperature and concentration gradients which then generate a density gradient. If the front propagates in the direction of the gravity field, adverse density stratification can lead to Rayleigh–Taylor or Rayleigh–Bénard instabilities. Differential diffusivity of mass and heat can also destabilize the front because of the double-diffusive phenomena. We compare the stability boundaries for the classical hydrodynamic case of a bounded layer without reaction and for the chemical front in the parameter space spanned by the thermal and solutal Rayleigh numbers. We show that chemical reactions profoundly affect the stability boundaries compared to the non-reactive situation because of a delicate coupling between the double-diffusive and Rayleigh–Taylor mechanisms with localized density perturbations driven by the reaction. In the reactive case, a linear stability analysis identifies three distinct stationary branches of the instability. They bound a region of stability that shrinks with increasing Lewis number, in marked contrast to the classical double-diffusive layer. In particular a region of global and local stable stratification is susceptible to a counter-intuitive mechanism of convective instability driven by chemistry and double-diffusion. The other two regions display an additional contribution of localized Rayleigh–Taylor instabilities. Displaced-particle arguments are employed in support of and to elucidate the entire stability boundary.
Effect of streamwise-periodic wall transpiration on turbulent friction drag
Authors: QUADRIO M. , FLORYAN J. M. , LUCHINI P.
Published: March 2007

In this paper a turbulent plane channel flow modified by a distributed transpiration at the wall, with zero net mass flux, is studied through direct numerical simulation (DNS) using the incompressible Navier–Stokes equations. The transpiration is steady, uniform in the spanwise direction, and varies sinusoidally along the streamwise coordinate. The transpiration wavelength is found to dramatically affect the turbulent flow, and in particular the frictional drag. Long wavelengths produce large drag increases even with relatively small transpiration intensities, thus providing an efficient means for improved turbulent mixing. Shorter wavelengths, on the other hand, yield an unexpected decrease of turbulent friction. These opposite effects are separated by a threshold of transpiration wavelength, shown to scale in viscous units, related to a longitudinal length scale typical of the near-wall turbulence cycle. Transpiration is shown to affect the flow via two distinct mechanisms: steady streaming and direct interaction with turbulence. They modify the turbulent friction in two opposite ways, with streaming being equivalent to an additional pressure gradient needed to drive the same flow rate (drag increase) and direct interaction causing reduced turbulent activity owing to the injection of fluctuationless fluid. The latter effect overwhelms the former at small wavelengths, and results in a (small) net drag reduction. The possibility of observing large-scale streamwise-oriented vortical structures as a consequence of a centrifugal instability mechanism is also discussed. Our results do not demonstrate the presence of such vortices, and the same conclusion can be arrived at through a stability analysis of the mean velocity profile, even though it is possible that a higher value of the Reynolds number is needed to observe the vortices.
The effect of disturbances on the flows under a sluice gate and past an inclined plate
Authors: BINDER B. J. , VANDEN-BROECK J.-M.
Published: March 2007

Free surface potential flows past disturbances in a channel are considered. Three different types of disturbance are studied: (i) a submerged obstacle on the bottom of a channel; (ii) a pressure distribution on the free surface; and (iii) an obstruction in the free surface (e.g. a sluice gate or a flat plate). Surface tension is neglected, but gravity is included in the dynamic boundary condition. Fully nonlinear solutions are computed by boundary integral equation methods. In addition, weakly nonlinear solutions are derived. New solutions are found when several disturbances are present simultaneously. They are discovered through the weakly nonlinear analysis and confirmed by numerical computations for the fully nonlinear problem.
Inertial effects in droplet spreading: a comparison between diffuse-interface and level-set simulations
Authors: DING HANG , SPELT PETER D. M.
Published: March 2007

Axisymmetric droplet spreading is investigated numerically at relatively large rates of spreading, such that inertial effects become important. Results from two numerical methods that use different means to alleviate the stress singularity at moving contact lines (a diffuse interface, and a slip-length-based level-set method) are shown to agree well. An initial inertial regime is observed to yield to a regime associated with Tanner's law at later times. The spreading rate oscillates during the changeover between these regimes. This becomes more significant for a fixed (effective) slip length when decreasing the value of an Ohnesorge number. The initial, inertia-dominated regime is characterized by a rapidly extending region affected by the spreading, giving the appearance of a capillary wave travelling from the contact line. The oscillatory behaviour is associated with the rapid collapse that follows the point at which this region extends to the entire droplet. Results are presented for the apparent contact angle as a function of dimensionless spreading rate for various values of Ohnesorge number, slip length and initial conditions. The results indicate that there is no such universal relation when inertial effects are important.
Australian exploration of Heard Island, 1947–1971
Authors: Budd Grahame M.
Published: March 2007

In 1947 knowledge of Heard Island was confined to a rough mapping compiled by nineteenth-century sealers, and the results of four scientific expeditions that had briefly investigated the Atlas Cove area. Exploration continued in two distinct periods between 1947 and 1971. In the first period the Australian National Antarctic Research Expeditions (ANARE) built a scientific station at Atlas Cove in 1947, and occupied it continuously until 1955 as an ‘A Class’ meteorological station, a seismic and magnetic observatory, and a base for other scientific studies and for exploration of the island. In the second period four summer expeditions and one wintering expedition worked on the island between 1963 and 1971. The summer expeditions were an ANARE expedition in 1963, an Australian private expedition (The South Indian Ocean Expedition to Heard Island) in 1965, and ANARE expeditions in 1969 and 1971 associated with United States and French expeditions. A United States expedition wintered in 1969. There were no further expeditions until 1980. The years 1947–1971 saw many achievements. Expedition members recorded seven years of synoptic meteorological observations and four years of seismic and magnetic observations. They developed empirical techniques of work, travel, and survival that shaped the collective character of ANARE and were later applied in Antarctica. Despite difficult terrain and consistently bad weather, and the accidental deaths of two men in 1952, unsupported field parties of two or three men travelling on foot explored and mapped in detail the heavily glaciated island, and documented its topography, geology, glaciology and biology. They made three overland circuits of the island, the first ascent of Big Ben (2745 m), and the first recorded landing on the nearby McDonald Islands. Expedition members bred and trained dog teams for later use in Antarctica. They reported the commencement and subsequent progress of massive glacier retreat caused by regional warming, and of the island's colonisation by king penguins (Aptenodytes patagonicus) and antarctic fur seals (Arctocephalus gazella). They also reported measurements of glacier flow and thickness, the palaeomagnetism of Heard Island rocks, behavioural and population studies of southern giant petrels (Macronectes giganteus) and other birds, studies of southern elephant seals (Mirounga leonina) and leopard seals (Hydrurga leptonyx), and the cold stress and acclimatisation experienced by humans working in the island's wet-cold climate. In addition, Heard Island served as a testing ground for men, equipment, scientific programmes, huskies, general administration, and logistics, without which Mawson station could not have been established as successfully as it was in 1954. The American wintering expedition and the French summer expedition contributed to major international geodetic and geophysical investigations. In sum, the expeditions between 1947 and 1971 added much to our knowledge of Heard Island, and they laid down a solid foundation for the work of later expeditions.
The breeding ecology of ruddy turnstones (Arenaria interpres) in the eastern Canadian Arctic
Authors: Perkins Deborah E. , Smith Paul A. , Gilchrist H. Grant
Published: March 2007

In 2002 and 2003, studies were made of the breeding phenology, nesting success, nesting density, and rates of nest predation of ruddy turnstones (Arenaria interpres) at East Bay, Southampton Island, Nunavut, Canada. Previous data from East Bay were used to compare nesting chronology and nest success across years. Bird banding data were used to examine migration routes and rates of return. In all years, ruddy turnstones initiated nests within 7 days of arrival at the study area. The median date of incubation onset was the same in 2002 and 2003, despite different spring snow conditions. Snow remained later in the season in 2003 and the overall range of incubation onset was greater than in 2002. Ruddy turnstones at East Bay nested at high densities and in semi-colonial groups with a significantly aggregated distribution. In both years, nest success was low, predation was high, and lemmings were scarce. These data (and data from earlier East Bay studies) support the ‘alternative prey hypothesis’. Resighting rates of breeding adults between 2002 and 2003 were also low. Individuals banded at East Bay were resighted at Delaware Bay on the Atlantic coast of the United States, the Caribbean Islands, and in southern Brazil. This study increases our knowledge of this understudied species about which there is conservation concern.
Henrik Bull, the Antarctic Exploration Committee and the first confirmed landing on the Antarctic continent
Authors: McConville Andrew
Published: March 2007

The Norwegian Henrik Johan Bull managed the Antarctic expedition that penetrated the Ross Sea in 1895 and made a landing at Cape Adare, the first confirmed landing on the Antarctic mainland. Bull had attempted to fund the voyage in Melbourne where he had lived since the late 1880s. At that time, Melbourne's learned societies, through their Antarctic Exploration Committee (AEC), were also making strenuous attempts to launch an expedition. The two parties had contact but the differences in their aims resulted in little cooperation. The AEC plans of a joint commercial/scientific expedition with Dundee or Norwegian whalers, and then a joint scientific expedition under Adolf Erik Nordenskiöld, foundered due to lack of funds. The plans to include a scientist, nominated by the learned societies, in Bull's expedition also failed. Instead, Carsten Egeberg Borchgrevink joined Bull's expedition as an ordinary seaman and an occasional scientist. He used this experience to realise his plans to winter on Antarctica. Both Bull and the AEC were important in developing interest in Antarctic exploration and commerce.
The hidden crime of Dr Richardson
Authors: Cavell Janice
Published: March 2007

Since the 1970s, a number of writers have endorsed the belief that Dr John Richardson very probably committed discreditable, and possibly even criminal, acts during the first Franklin expedition (1819–1822). These acts, they allege, were concealed from the public by Franklin and Richardson, who inserted a fabricated account into Franklin's 1823 narrative. This paper examines the evidence and arguments put forward by the originator of this theory, the historian Richard Glover. It concludes that Glover was motivated primarily by a desire to vindicate the good name of another explorer, Samuel Hearne. Richardson had suggested that Hearne's narrative was not an entirely reliable account of his travels, and in Glover's view, these remarks had seriously damaged Hearne's reputation. Glover therefore sought to characterise Richardson as a deceitful man of exceptionally poor judgement, upon whose claims no reliance could be placed. Later writers, engaged in a re-evaluation of Britain's imperial activities in the Canadian north, have accepted and expanded on Glover's theories. However, an examination of the primary sources cited by Glover and others demonstrates that there is no solid basis for the revisionist version of the 1819–1822 expedition.
An integrated approach to the mapping of Canada's north
Authors: Clavet Daniel , Beaulieu Alexandre
Published: March 2007

Between 2003 and 2006, the Centre for Topographic Information in Sherbrooke (CTI), Québec, under the Canadian Space Agency (CSA) Government Related Initiatives Programme (GRIP), conducted a project (Cartonord project) aimed at new base mapping at a scale of 1:50,000 for unmapped areas of northern Canada using earth observation data.
An incident of polar bear infanticide and cannibalism on Phippsøya, Svalbard
Authors: Stone Ian R. , Derocher Andrew E.
Published: March 2007

A case of polar bear infanticide and cannibalism is reported from Phippsøya, Svalbard. In this instance, a cub of some 7 months was killed by an adult male bear, which was in poor condition, in the close proximity of the mother, which was also in poor condition. It seems probable that the attack was made for nutritional gain.
A preliminary archaeological survey of a Tupolev TB-3 (ANT-6) aircraft on Ostrov Rudol'fa, Zemlya Frantsa-Iosifa, Russia
Authors: Capelotti P.J.
Published: March 2007

The partially snow-covered wreck of specially-modified Arctic variant of the Tupolev TB-3 four-engine bomber was located at Buhkta Teplits [Teplits Bay], Ostrov Rudol'fa [Rudolf Island] in Zemlya Frantsa-Iosifa [Franz Josef Land]. From data gathered, the wreck was subsequently identified as TB-3 (ANT-6) No. 210. This aircraft was piloted by Boris Chukhnovsky during a failed search for another TB-3 (ANT-6), No. 209, which had been lost in August 1937 during an attempt to fly from Moscow over the north pole to the United States. The Teplits TB-3 (ANT-6) wreck represents both the primary aeronautical archaeology of the triumphs and disasters of the Soviet Union's air expeditions to the pole in 1937–1938 and, at 81°47.5'N, is the northernmost aircraft wreck yet identified.
Ovine helminthosis, a major health constraint to productivity of sheep in Ethiopia
Authors: Biffa Demelash , Jobre Yilma , Chakka Hassen
Published: March 2007

Small ruminants represent an important component of the Ethiopian livestock production system, providing 12% of the value of livestock products consumed at the farm level and 48% of the cash income generated. Ethiopia is second in Africa and sixth in the world in terms of sheep population. The country has, however, benefited little from this enormous resource owing to a multitude of problems, disease being the most important. Disease alone accounts for mortalities of 30% in lambs and 20% in adults. Productivity losses attributable to helminth parasites are often substantial. A loss of US[dollar] 81.8 million is reported annually due to helminth parasites. In a country confronted with challenges of an ever-rising human population and food shortage, such enormous losses caused by helminth parasites, ‘the silent predators’, are intolerable. Therefore, helminth control should receive special attention in poverty reduction strategies through improved productivity of livestock if the present and future challenges of food shortage are to be addressed. Productivity loss due to helminth infections can be substantially reduced through implementation of effective disease control strategies, which require an understanding of the epidemiology and ecology of parasites and parasitic infections under local conditions. This paper reviews extensive evidence demonstrating that helminthosis is a major constraint to productivity of sheep in Ethiopia. It also discusses epidemiology and ecology of major helminth parasites in the country and suggests strategies for improved control in various agro-ecological zones and production systems.