bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification and updating for the three‐dimensional finite element model of a long span steel skybridge
Authors: Zhao X. , Sun H. H. , Zheng Y. M.
Published: February 2009

An identification and updating procedure for the three‐dimensional finite element (FE) model of a long span steel skybridge is presented in this paper. Located at an elevation of 90 m, the skybridge is one of the six skybridges of Hangzhou Citizen Center, which is a hexadic‐tower tall building. The modal data of the skybridge is first estimated using output only identification method, and sensitivity‐based updating method is then applied to update the three‐dimensional FE model based on the estimated modal data. For the modal data identification, a time domain least square method and a data smoothing method were applied for pre‐processing the recorded acceleration time histories. The averaged normalized power spectral density was then used in the peak‐picking method to identify the natural frequencies. The updating algorithm is composed of sensitivity analysis and Bayesian estimation, and the parameter perturbations are estimated using a constrained optimization method. It is found that far better matches can be reached between the updated and estimated dynamic characteristics by using the proposed identification and updating procedure. Copyright © 2009 John Wiley & Sons, Ltd.
PSA testing in the UK
Authors: Melia Jane , Moss Sue
Published: February 2009

Despite there being no evidence at present that screening for prostate cancer reduces mortality, there has been a steep rise in the use of the prostate‐specific antigen test. Trials are underway that will shed light on the effects of screening and treatment in the future, but until then testing should proceed with caution. Copyright © 2009 Wiley Interface Ltd
Management of ovarian masses in pregnancy
Authors: Elhalwagy Hosam
Published: February 2009

With the increasing use of prenatal ultrasonography, identification of ovarian masses during pregnancy is becoming more common. The author considers how these can be evaluated and managed, and looks at factors that may help determine the need for surgical intervention. Copyright © 2009 Wiley Interface Ltd
ARMA: a scalable secure routing protocol with privacy protection for mobilead hocnetworks
Authors: Ren Yonglin , Boukerche Azzedine
Published: February 2009

With the rapidly growing popularity of mobilead hocnetworks (MANETs), many security concerns have arisen from this type of network. In particular, malicious nodes will jeopardize the security of mobile networks if the issues of secure data exchange are not handled properly. Encryption cannot fully protect the data communicated between nodes, as routing information may expose the identities of the communicating nodes and put their relationships at risk. In this paper, we propose an efficient anonymous routing protocol that uses a mobile agent paradigm for MANETs, which we refer to as ARMA. In our protocol, we take advantage of a trust system to prevent effectively the misbehavior of malicious nodes so that only trustworthy nodes are allowed to participate in communications. Furthermore, we present theMalicious EncryptionandMalicious IDattacks, as well as other attacks, and note how our scheme is robust to them. Through the proof of protocol correctness, our protocol is analyzed to show how it offers provable security properties. Finally, we provide its performance evaluation based on simulation experiments implemented in anns‐2simulator. Compared to the secure distributed route construction protocol (SDAR) protocol, our experimental results demonstrate that our scheme not only achieves the necessary anonymity in wireless and mobile networks, but also provides more security with reasonably little additional overhead. Copyright © 2009 John Wiley & Sons, Ltd.
Investigation of capacity and call admission control schemes in TD‐SCDMA uplink systems employing smart antenna techniques
Authors: Peng Mugen , Wang Wenbo , Zhang Jie
Published: February 2009

Due to the TDMA (time division multiple access)/time division duplex (TDD) specialization in the uplink (UL) of code division multiplex access (CDMA) systems, some advanced techniques, such as smart antenna (SA) and multi‐user detection (MUD), are utilized conveniently in time division‐synchronous code division multiplex access (TD‐SCDMA) systems. These advanced techniques have great impacts on the capacity and radio resource management (RRM) schemes. In this paper, the UL capacity and load models specified for TD‐SCDMA systems are proposed, in which the impacts from SA and MUD techniques are considered, and the UL load can be estimated based on the total received power in the base station. According to the proposed theoretical capacity and load evaluation models, the call admission control (CAC) strategies suitable for TD‐SCDMA systems are presented. Since there are two kinds of SA schemes (i.e., tracking beam antenna (TBA) and switched beam antenna (SBA)) utilized in TD‐SCDMA systems, the efficient CAC algorithms suitable for these two SA schemes are designed and evaluated, which are based on principles of the interference increase estimation. All simulation results show that the proposed CAC strategies can work efficiently and improve performances of TD‐SCDMA systems dramatically. Copyright © 2009 John Wiley & Sons, Ltd.
Repeated elements coordinate the spatial organization of the yeast genome
Authors: O'Sullivan J. M. , Sontam D. M. , Grierson R. , Jones B.
Published: February 2009

The spatial organization of the chromosomes is crucial for gene expression and development. Inter‐ and intrachromosomal interactions form a crucial part of this epigenomic regulatory system. Here we use circular chromosome conformation capture‐on‐chip (4C) to identify interactions between repetitive and non‐repetitive loci within the yeast genome. The interacting regions occur in non‐randomly distributed clusters. Furthermore, the SIR2 histone deacetylase has opposing roles in the organization of the inter‐ or intrachromosomal interactions. These data establish a dynamic domain model for yeast genome organization. Moreover, they point to the repeated elements playing a central role in the dynamic organization of genome architecture. Copyright © 2009 John Wiley & Sons, Ltd.
Deconstructing Sodalite with Hyperbolic Tilings: A PNS Approach
Authors: Leoni Stefano
Published: February 2009

Hyperbolic tilings on periodic nodal surfaces (PNS) are used to construct scaffoldings of interpenetrating nets, which are employed to deconstruct sodalite into interpenetrating (10,3)‐a Wells nets and to describe MOF frameworks. This is intended as an illustration of a two‐dimensional, non‐Euclidean perspective on the understanding and engineering of structured matter.
Endoparasitism in captive wild‐caught snakes indigenous to Kerala, India
Authors: Radhakrishnan S. , Kurup S. P. , Banerjee P. S.
Published: February 2009

In this preliminary survey, coprologic examination of six different captive snake species housed in three different herpetariums of Kerala state was conducted from July 2005 to January 2006, to study the prevalence of endoparasites. Of the 25 snakes examined, 22 (88%) were found infected. On the basis of morphology and morphometry, Capillaria spp. (72%), strongyle (28%), spirurid (20%), Strongyloides/Rhabdias spp. (16%), ascarid (12%), pseudophyllidean tapeworm (8%), acanthocephalan (4%) and pentastomid (12%) ova were identified. The occurrence of ova of Hymenolepis spp. as pseudoparasite was also noticed. Zoo Biol 28:253–258, 2009. © 2009 Wiley‐Liss, Inc.
Enhancing captive breeding in giant pandas (Ailuropoda melanoleuca): maintaining lactation when cubs are rejected, and understanding variation in milk collection and associated factors
Authors: Wei Rongping , Zhang Guiquan , Yin Feng , Zhang Hemin , Liu Dingzhen
Published: February 2009

From 1997 to 2002, a female giant panda (Ailuropoda melanoleuca) was artificially stimulated and lactation was maintained, after her neonates were removed due to the female's inability to provide maternal care. Milk samples were collected and the amount of milk collected was quantified. The lactation curve of this animal was estimated based on the Gamma function: Yt=atbe−ct. The amount of milk collected showed significant, positive relationships with the number of days after parturition both in 1999 and in the whole study period from 1998 to 2002. This female's lactation curves fit the type I pattern of a typical mammalian lactation curve. Daily milk collection (g) during the first 30 days after parturition, and from 31 to 60 days after parturition, showed a consistent pattern with one peak at around 8:00 hr. More milk was collected during the latter period than during the former period. The amount of milk (g) collected on mucus excretion days was significantly less than that on days after mucus excretion had ended, yet no significant difference was found between milk collected one day before mucus days and on mucus days, or between milk collected one day before and one day after mucus days. Mucus excretion from the gastrointestinal tract significantly impacted the amount of milk collected. The results from this study may aid the captive propagation and conservation of giant pandas and other endangered and rare captive mammal species. Zoo Biol 28:331–342, 2009. © 2009 Wiley‐Liss, Inc.
Life span, reproductive output, and reproductive opportunity in captive Goeldi's monkeys (Callimico goeldii)
Authors: Nuss Kara , Warneke Mark
Published: February 2009

In the absence of long‐term field studies, demographic and reproductive records from animals housed in zoos and research laboratories are a valuable tool for the study of life history variables relating to reproduction. In this study, we analyzed studbook records of more than 2,000 individuals born over a 40‐year period (1965–2004) to describe life history patterns of captive Goeldi's monkeys (Callimico goeldii) housed in North America and Europe. Using Kaplan–Meier survival analysis methods, we found the mean life span to be 5.5 years. The rate of infant mortality, defined as death before 30 days, was approximately 30%, with European animals being more likely to survive infancy than North American animals. When individuals surviving at least 1.5 years are considered, lifetime reproductive output averaged 3.5 offspring, yet more than one‐third of individuals did not produce any offspring. Using a smaller dataset of individuals with known pairing histories, we developed a measure of opportunity for reproduction (OFR), which represented the total time an individual was known to be housed with a potential mate. For both sexes, we found that the correlation between OFR and number of offspring produced was much higher than the correlation between life span and number of offspring produced. This result highlights the importance of taking into account an individual's OFR. As a whole, our findings help characterize the life histories of captive Goeldi's monkeys and emphasize the impact management practices may have on reproductive success. Zoo Biol 29:1–15, 2010. © 2009 Wiley‐Liss, Inc.
Plasma carnitine ester profile in homozygous and heterozygous OCTN2 deficiency
Authors: Komlósi K. , Magyari L. , Talián G. C. , Nemes É. , Káposzta R. , Mogyorósy G. , Méhes K. , Melegh B.
Published: February 2009

The carnitine ester spectrum was studied using ESI tandem mass spectrometry in a 2.5‐year‐old male Roma child with homozygous deletion of 844C of the SLC22A5 gene, presenting with hepatopathy and cardiomyopathy. Besides the dramatic decrease of plasma free carnitine (1.38 vs 32.7 μmol/L in controls) all plasma carnitine esters were severely decreased in the proband: the total esters were 31.4% of the controls. In three heterozygous siblings the free carnitine level was 62.3% of the normal controls, while the levels of the individual carnitine esters ranged between 15.5% and 163% (average 70.9%). The heterozygous parents exhibited the same pattern. The proband was supplemented with 50 mg/kg per day of l‐carnitine oral solution. After 2 months of treatment, his hepatomegaly, elevated transaminases and the pathological cardiac ultrasound parameters normalized. The plasma free carnitine rose to 12.8 μmol/L (39% of the controls). All of the carnitine esters also increased; however, the individual esters were still 8.5–169.7% of the controls (average 55.5%). After 13 months of treatment there was a further increase in free carnitine (15.9 μmol/L) as well as in the level of the individual esters, ranging between 16.1% and 140.3% of the controls (average 66.9%). The data presented here show that, besides the dramatic decrease of free carnitine, the carnitine ester metabolism is also affected in OCTN2 deficiency; the replenishment of the pools under treatment is slow. Despite an impressive clinical improvement, the carnitine metabolism can be still seriously affected.
New treatment paradigms in neonatal metabolic epilepsies
Authors: Pearl P. L.
Published: February 2009

Neonatal seizures represent a major challenge among the epilepsies vis‐à‐vis seizure classification, electroclinical correlation, inherent excitability of neocortex, ontogenic characteristics of neurotransmitter receptors, and responsiveness to standard antiepileptic drugs. Each of these factors renders neonatal seizures more difficult to treat, and therapy has been a vexing area for recent advances in this seizure category. Conversely, specific metabolic disorders have very special therapeutic considerations in the clinical setting of neonatal seizures which require a high index of clinical suspicion and rapid intervention for a successful outcome. The prototype is pyridoxine dependency, although pyridoxal 5′‐phosphate dependency is a recently recognized but treatable neonatal epilepsy that deserves earmarked distinction. Clinicians must remain vigilant for these possibilities, including atypical cases where apparent seizure‐free intervals may occur. Folinic acid‐dependent seizures are allelic with pyridoxine dependency. Serine‐dependent seizures and glucose transporter deficiency may present with neonatal seizures and have specific therapy. A vital potassium channel regulated by serum ATP/ADP ratios in the pancreas and brain may be mutated with a resultant neuroendocrinopathy characterized by development delay, epilepsy, and neonatal diabetes (DEND). This requires oral hypoglycaemic therapy, and not insulin, for neurological responsiveness. The startle syndrome of hyperekplexia, which mimics neonatal epilepsy, has been associated with laryngospasm and sudden death but is treated with benzodiazepines.
pH‐Dependent Fe (II) pathophysiology and protective effect of an organoselenium compound
Authors: Hassan Waseem , Ibrahim Mohammad , Deobald Anna Maria , Braga Antonio Luiz , Nogueira Cristina Wayne , Rocha Joao B.T.
Published: February 2009

Influence of pH on the extent of lipid peroxidation and the anti‐oxidant potential of an organoselenium compound is explored. Acidosis increased the rate of lipid peroxidation both in the absence and presence of Fe (II) in rat's brain, kidney and liver homogenate and phospholipids extract from egg yolk. The organoselenium compound significantly protected lipids from peroxidation, both in the absence and presence of Fe (II). Changing the pH of the reaction medium did not alter the anti‐oxidant activity of the tested compound. This study provides in vitro evidence for acidosis‐induced oxidative stress in brain, kidney, liver homogenate and phospholipids extract and the anti‐oxidant action of the tested organoselenium compound.
Insight into “insoluble proteins” with pure water
Authors: Song Jianxing
Published: February 2009

Many proteins are not refoldable and also insoluble. Previously no general method was available to solubilize them and consequently their structural properties remained unknown. Surprisingly, we recently discovered that all insoluble proteins in our laboratory, which are highly diverse, can be solubilized in pure water. Structural characterization by CD and NMR led to their classification into three groups, all of which appear trapped in the highly disordered or partially‐folded states with a substantial exposure of hydrophobic side chains. In this review, I discuss our results in a wide context and subsequently propose a model to rationalize the discovery. The potential applications are also explored in studying protein folding, design and membrane proteins.
Identification of a polymorphism in the RING finger of human Bmi‐1 that causes its degradation by the ubiquitin–proteasome system
Authors: Zhang Jie , Sarge Kevin D.
Published: February 2009

MINT‐6948574: Bmi‐1 (uniprotkb:P35226) physically interacts (MI:0218) with Ubiquitin (uniprotkb:P62988) by anti tag coimmunoprecipitation (MI:0007)
Knowledge, practices, and attitudes regarding emergency contraception among students at a university in Ghana
Authors: Addo Victor N. , Tagoe‐Darko Eva Dede
Published: February 2009

Objectives

To investigate the knowledge, practices, and attitudes among students at a university in Ghana regarding emergency contraception (EC).

Methods

An anonymous, self‐administered, 39‐item questionnaire was sent to 3200 students. The sample size was stratified and 2292 students were randomly selected.

Results

Of the 71.6% of students who responded, 51.4% had heard of EC. Among those, 19.4% thought EC consisted of contraceptive pills, 19.1% of “morning‐after pills,” and 12.8% of an intrauterine device. Only 4.2% had ever used EC but 73.9% wished it were provided on campus. Of all the respondents, 90.9% called for the establishment of a reproductive health counseling center on campus.

Conclusion

Student knowledge and use of EC were poor, and there is urgent need for reproductive counseling and EC services on campus.
Hierarchy of earthquakes in the Baikal rift system: implications for lithospheric stress
Authors: Klyuchevskii A.V. , Dem’yanovich V.M. , Dzhurik V.I.
Published: February 2009

We investigated space-time lithospheric stress patterns of the Baikal rift system according to the hierarchy of earthquakes using mechanisms of 265 KP ≥ 10 events recorded from 1950 to 1998 and seismic moments of 802 KP≥ 11 events from 1968 to 1994. The lithosphere of the region was confirmed to undergo rifting with mostly normal-slip events, while local areas of frequent strike-slip and reverse motions may record stress heterogeneity. The dominance of rifting, although being evident in the stress dynamics, is unstable, which is indicated by increase in strike-slip and reverse motions to as many as normal slip events in the latest 1980s–earliest 1990s. The lithospheric stress patterns inferred from seismic-moment data are generally consistent with those derived from the classical focal mechanism method. The suggested approach of seismic zoning according to earthquake slip geometry may provide a more reliable background for successful mitigation of seismic hazard in the region.
The Berezitovoe gold-polymetallic deposit (East Siberia): mineralogy, age, and relation with magmatism
Authors: Mel’nikov A.V. , Sorokin A.A. , Ponomarchuk V.A. , Travin A.V. , Sorokin A.P.
Published: February 2009

The Berezitovoe gold-polymetallic deposit is localized in the west of the Selenga–Stanovoi superterrane composed of a wide spectrum of Early and Late Precambrian igneous rocks and abundant Paleozoic and Mesozoic intrusive and volcanoplutonic associations. The 40Ar/39Ar ages determined for metasomatites bearing gold-polymetallic mineralization are as follows: garnet-quartz-muscovite-sericite-K-feldspathic metasomatites (129.7±3.2–127.3±4.4 Ma); muscovite-quartz-sericite metasomatites (132.0±2.9–131.3±2.3 Ma). According to the age and general scheme of evolution of the Early Cretaceous magmatism in the Selenga–Stanovoi superterrane, the metasomatites of the Berezitovoe deposit are nearly coeval to the intrusive rocks of the Amudzhikan complex (132–128 Ma). The revealed platinum potential of gold-polymetallic ores and metasomatites permits ranking the Berezitovoe deposit as a specific complex gold-polymetallic-platinum deposit, which considerably increases its commercial value.
Understanding the offshore flood basalt sequence using onshore volcanic facies analogues: an example from the Faroe–Shetland basin
Authors: JERRAM DOUGAL A. , SINGLE RICHARD T. , HOBBS RICHARD W. , NELSON CATHERINE E.
Published: February 2009

Flood basalts in associated volcanic rifted margins, such as the North Atlantic Igneous Province, have a significant component of lavas which are preserved in the present day in an offshore setting. A close inspection of the internal facies architecture of flood basalts onshore provides a framework to interpret the offshore sequences imaged by remote techniques such as reflection seismology. A geological interpretation of the offshore lava sequences in the Faroe–Shetland Basin, using constraints from onshore analogues such as the Faroe Islands, allows for the identification of a series of lava sequences which have characteristic properties so that they can be grouped. These are tabular simple flows, compound-braided flows, and sub-aqueously deposited hyaloclastite facies. The succession of volcanic rocks calculated in this study has a maximum thickness in excess of 6800 m. Down to the top of the sub-volcanic sediments, the offshore volcanic succession has a thickness of about 2700 m where it can be clearly identified across much of the area, with a further 2700 m or more of volcanic rock estimated from the combined gravity and seismic modelling to the north and west of the region. A large palaeo-waterbody is identified on the basis of a hyaloclastite front/apron consisting of a series of clinoforms prograding towards the eastern part of the basin. This body was > 500 m deep, must have been present at the onset of volcanism into this region, and parts of the water body would have been present during the continued stages of volcanism as indicated by the distribution of the hyaloclastite apron.
Unsteady natural convection in a triangular enclosure induced by absorption of radiation – a revisit by improved scaling analysis
Authors: MAO YADAN , LEI CHENGWANG , PATTERSON JOHN C.
Published: February 2009

The present study is concerned with radiation-induced natural convection in a water-filled triangular enclosure with a sloping bottom, which is directly relevant to buoyancy-driven flows in littoral regions. An improved scaling analysis is carried out to reveal more detailed features of the flow than a previously reported analysis. Two critical functions of the Rayleigh number with respect to the horizontal position are derived from the scaling for identifying the distinctness and stability of the thermal boundary layer. Four flow scenarios are possible, depending on the bottom slope and the maximum water depth. For each flow scenario, the flow domain may be composed of multiple subregions with distinct thermal and flow features, depending on the Rayleigh number. The dividing points between neighbouring subregions are determined by comparisons of the critical functions of the Rayleigh number with the global Rayleigh number. Position-dependent scales have been established to quantify the flow properties in different subregions. The different flow regimes for the case with relatively large bottom slopes and shallow waters are examined in detail. The present scaling results are verified by numerical simulations.
Three-dimensional instantaneous structure of a shock wave/turbulent boundary layer interaction
Authors: HUMBLE R. A. , ELSINGA G. E. , SCARANO F. , van OUDHEUSDEN B. W.
Published: February 2009

An experimental study is carried out to investigate the three-dimensional instantaneous structure of an incident shock wave/turbulent boundary layer interaction at Mach 2.1 using tomographic particle image velocimetry. Large-scale coherent motions within the incoming boundary layer are observed, in the form of three-dimensional streamwise-elongated regions of relatively low- and high-speed fluid, similar to what has been reported in other supersonic boundary layers. Three-dimensional vortical structures are found to be associated with the low-speed regions, in a way that can be explained by the hairpin packet model. The instantaneous reflected shock wave pattern is observed to conform to the low- and high-speed regions as they enter the interaction, and its organization may be qualitatively decomposed into streamwise translation and spanwise rippling patterns, in agreement with what has been observed in direct numerical simulations. The results are used to construct a conceptual model of the three-dimensional unsteady flow organization of the interaction.
Phase-field model for the Rayleigh–Taylor instability of immiscible fluids
Authors: CELANI ANTONIO , MAZZINO ANDREA , MURATORE-GINANNESCHI PAOLO , VOZELLA LARA
Published: February 2009

The Rayleigh–Taylor instability of two immiscible fluids in the limit of small Atwood numbers is studied by means of a phase-field description. In this method, the sharp fluid interface is replaced by a thin, yet finite, transition layer where the interfacial forces vary smoothly. This is achieved by introducing an order parameter (the phase-field) continuously varying across the interfacial layers and uniform in the bulk region. The phase-field model obeys a Cahn–Hilliard equation and is two-way coupled to the standard Navier–Stokes equations. Starting from this system of equations we have first performed a linear analysis from which we have analytically rederived the known gravity–capillary dispersion relation in the limit of vanishing mixing energy density and capillary width. We have performed numerical simulations and identified a region of parameters in which the known properties of the linear phase (both stable and unstable) are reproduced in a very accurate way. This has been done both in the case of negligible viscosity and in the case of non-zero viscosity. In the latter situation, only upper and lower bounds for the perturbation growth rate are known. Finally, we have also investigated the weakly nonlinear stage of the perturbation evolution and identified a regime characterized by a constant terminal velocity of bubbles/spikes. The measured value of the terminal velocity is in agreement with available theoretical prediction. The phase-field approach thus appears to be a valuable technique for the dynamical description of the stages where hydrodynamic turbulence and wave-turbulence come into play.
Direct numerical simulation of the pulsatile flow through an aortic bileaflet mechanical heart valve
Authors: DE TULLIO M. D. , CRISTALLO A. , BALARAS E. , VERZICCO R.
Published: February 2009

This work focuses on the direct numerical simulation of the pulsatile flow through a bileaflet mechanical heart valve under physiological conditions and in a realistic aortic root geometry. The motion of the valve leaflets has been computed from the forces exerted by the fluid on the structure both being considered as a single dynamical system. To this purpose the immersed boundary method, combined with a fluid–structure interaction algorithm, has shown to be an inexpensive and accurate technique for such complex flows. Several complete flow cycles have been simulated in order to collect enough phase-averaged statistics, and the results are in good agreement with experimental data obtained for a similar configuration. The flow analysis, strongly relying on the data accessibility provided by the numerical simulation, shows how some features of the leaflets motion depend on the flow dynamics and that the criteria for the red cell damages caused by the valve need to be formulated using very detailed analysis. In particular, it is shown that the standard Eulerian computation of the Reynolds stresses, usually employed to assess the risk of haemolysis, might not be adequate on several counts: (i) Reynolds stresses are only one part of the solicitation, the other part being the viscous stresses, (ii) the characteristic scales of the two solicitations are very different and the Reynolds stresses act on lengths much larger than the red cells diameter and (iii) the Eulerian zonal assessment of the stresses completely misses the information of time exposure to the solicitation which is a fundamental ingredient for the phenomenon of haemolysis. Accordingly, the trajectories of several fluid particles have been tracked in a Lagrangian way and the pointwise instantaneous viscous stress tensor has been computed along the paths. The tensor has been then reduced to an equivalent scalar using the von Mises criterion, and the blood damage index has been evaluated following Grigioni et al. (Biomech. Model Mechanobiol., vol. 4, 2005, p. 249).
A generalized vortex ring model
Authors: KAPLANSKI FELIX , SAZHIN SERGEI S , FUKUMOTO YASUHIDE , BEGG STEVEN , HEIKAL MORGAN
Published: February 2009

A conventional laminar vortex ring model is generalized by assuming that the time dependence of the vortex ring thickness ℓ is given by the relation ℓ = atb, where a is a positive number and 1/4 ≤ b ≤ 1/2. In the case in which $a=\sqrt{2\nu}$, where ν is the laminar kinematic viscosity, and b = 1/2, the predictions of the generalized model are identical with the predictions of the conventional laminar model. In the case of b = 1/4 some of its predictions are similar to the turbulent vortex ring models, assuming that the time-dependent effective turbulent viscosity ν∗ is equal to ℓℓ′. This generalization is performed both in the case of a fixed vortex ring radius R0 and increasing vortex ring radius. In the latter case, the so-called second Saffman's formula is modified. In the case of fixed R0, the predicted vorticity distribution for short times shows a close agreement with a Gaussian form for all b and compares favourably with available experimental data. The time evolution of the location of the region of maximal vorticity and the region in which the velocity of the fluid in the frame of reference moving with the vortex ring centroid is equal to zero is analysed. It is noted that the locations of both regions depend upon b, the latter region being always further away from the vortex axis than the first one. It is shown that the axial velocities of the fluid in the first region are always greater than the axial velocities in the second region. Both velocities depend strongly upon b. Although the radial component of velocity in both of these regions is equal to zero, the location of both of these regions changes with time. This leads to the introduction of an effective radial velocity component; the latter case depends upon b. The predictions of the model are compared with the results of experimental measurements of vortex ring parameters reported in the literature.
The onset of convection in rotating circular cylinders with experimental boundary conditions
Authors: ZHANG KEKE , LIAO XINHAO
Published: February 2009

Convective instabilities in a fluid-filled circular cylinder heated from below and rotating about its vertical axis are investigated both analytically and numerically under experimental boundary conditions. It is found that there exist two different forms of convective instabilities: convection-driven inertial waves for small and moderate Prandtl numbers and wall-localized travelling waves for large Prandtl numbers. Asymptotic solutions for both forms of convection are derived and numerical simulations for the same problem are also performed, showing a satisfactory quantitative agreement between the asymptotic and numerical analyses.
Asymptotic model for the dynamics of curved viscous fibres with surface tension
Authors: MARHEINEKE NICOLE , WEGENER RAIMUND
Published: February 2009

In this paper, we derive and investigate an asymptotic model for the dynamics of curved viscous inertial Newtonian fibres subjected to surface tension, as they occur in rotational spinning processes. Accordingly, we extend the slender body theory of Panda, Marheineke & Wegener (Math. Meth. Appl. Sci., vol. 31, 2008, p. 1153) by including surface tension and deducing boundary conditions for the free end of the fibre. The asymptotic model accounts for the inner viscous transport and places no restrictions on either the motion or the shape of the fibre centreline. Depending on the capillary number, the boundary conditions yield an explicit description for the temporal evolution of the fibre end. We study numerically the behaviour of the fibre as a function of the effects of viscosity, gravity, rotation and surface tension.
On the equilibration of a symmetrically unstable front via a secondary shear instability
Authors: TAYLOR JOHN R. , FERRARI RAFFAELE
Published: February 2009

The equilibration of a symmetrically unstable density front is examined using linear stability theory and nonlinear numerical simulations. The initial state, chosen to approximate conditions in the surface ocean, consists of a weakly stratified mixed layer above a strongly stratified thermocline. Each layer has a uniform horizontal density gradient and a velocity field in thermal wind balance. The potential vorticity (PV) in the mixed layer is negative, indicating conditions favourable for symmetric instability. Once the instability reaches finite amplitude, a secondary Kelvin–Helmholtz (K-H) instability forms. Linear theory accurately predicts the time and the wavenumber at which the secondary instability occurs. Following the secondary instability, small-scale turbulence injects positive PV into the mixed layer from the thermocline and from the upper boundary, resulting in a rapid equilibration of the flow as the PV is brought back to zero. While the physical parameters used in this study correspond to typical conditions near a surface ocean front, many of the conclusions apply to symmetric instabilities in the atmosphere.
Numerical study of the effects of the breaking intensity on wave breaking flows
Authors: IAFRATI A.
Published: February 2009

The flow generated by the breaking of free-surface waves of different initial steepnesses is simulated numerically. The aim is to investigate the role played by the breaking intensity on the resulting flow. The study, which assumes a two-dimensional flow, makes use of a two-fluids Navier–Stokes solver combined with a Level-Set technique for the interface capturing. The evolution of periodic wavetrains is considered. Depending on the initial steepness ϵ, the wavetrain remains regular or develops a breaking, which can be either of spilling or plunging type. From the analysis of the local strain fields it is shown that, in the most energetic phase of plunging breaking, dissipation is mainly localized about the small air bubbles generated by the fragmentation of the air cavity entrapped by the plunging of the jet. The downward transfer of the horizontal momentum is evaluated by integrating the flux of momentum through horizontal planes lying at different depths beneath the still water level. From weak to moderate breaking, increase in the breaking intensity results in growing transfer of horizontal momentum, as well as thickening of the surface layer. Beyond a certain breaking intensity, the larger amount of air entrapped causes a reduction in the momentum transferred and the shrinkage of the layer. Quantitative estimates of the amount of air entrapped by the breaking and of the degassing process are provided. A scaling dependence of the amount of air entrapped by the first plunging event on the initial steepness is found. A careful analysis of the circulation induced in water by the breaking process is carried out. It is seen that in the plunging regime the primary circulation induced by the breaking process scales with the velocity jump between the crest and the trough of the wave.

The limits of the main assumptions of the numerical calculations are analysed. It is shown that up to half-wave period after the breaking onset, the Reynolds number of the simulation does not significantly affect the solution. In order to further support the findings, an estimate of the uncertainty of the numerical results is derived through several repetitions of the numerical simulation with small perturbations of the initial conditions.
Pulsatile flow in stenotic geometries: flow behaviour and stability
Authors: GRIFFITH M. D. , LEWEKE T. , THOMPSON M. C. , HOURIGAN K.
Published: February 2009

Pulsatile inlet flow through a circular tube with an axisymmetric blockage of varying size is studied both numerically and experimentally. The geometry consists of a long, straight tube and a blockage, semicircular in cross-section, serving as a simplified model of an arterial stenosis. The stenosis is characterized by a single parameter, the aim being to highlight fundamental behaviours of constricted pulsatile flows. The Reynolds number is varied between 50 and 700 and the stenosis degree by area between 0.20 and 0.90. Numerically, a spectral element code is used to obtain the axisymmetric base flow fields, while experimentally, results are obtained for a similar set of geometries, using water as the working fluid. For low Reynolds numbers, the flow is characterized by a vortex ring which forms directly downstream of the stenosis, for which the strength and downstream propagation velocity vary with the stenosis degree. Linear stability analysis is performed on the simulated axisymmetric base flows, revealing a range of absolute instability modes. Comparisons are drawn between the numerical linear stability analysis and the observed instability in the experimental flows. The observed flows are less stable than the numerical analysis predicts, with convective shear layer instability present in the experimental flows. Evidence is found of Kelvin–Helmholtz-type shear layer roll-ups; nonetheless, the possibility of the numerically predicted absolute instability modes acting in the experimental flow is left open.
Aptitude, phonological memory, and second language proficiency in nonnovice adult learners
Authors: HUMMEL KIRSTEN M.
Published: February 2009

This study explores the relationship between aptitude, phonological memory (PM), and second language (L2) proficiency in nonnovice adult learners of English as an L2. Native speakers of French (N= 77) enrolled in a university Teaching English as a Second Language program were the participants in the study. Exploratory factor analysis revealed three main factors corresponding to the variables examined: L2 proficiency, aptitude, and PM. Multiple regression analyses revealed aptitude subtests and PM together predicted 29% of the variance in L2 proficiency. Additional regression analyses carried out on lower and higher proficiency subgroups, created by a median split on proficiency scores, revealed that none of the variables predicted L2 proficiency in the higher proficiency subgroup. PM remained as a significant predictor for the lower proficiency subgroup, extending the pattern of results found elsewhere in younger populations to adult nonnovice L2 learners.
Economy in the acquisition of English universal quantifier sentences: The interpretations of deaf and hearing students and second language learners at the college level
Authors: BERENT GERALD P. , KELLY RONALD R. , SCHUELER-CHOUKAIRI TANYA
Published: February 2009

English sentences containing the universal quantifiers each, every, and all are highly complex structures in view of the subtleties of their scope properties and resulting ambiguities. This study explored the acquisition of universal quantifier sentences as reflected in the performance of three diverse college-level student groups on a multipicture sentence interpretation task. The participant groups (hearing native speakers, deaf students, and second language learners of English) all exhibited fundamental knowledge of universal lexical, semantic, and syntactic properties that contribute to quantifier sentence interpretation. The native speakers outperformed the deaf and second language groups, whose performance was strikingly parallel. Performance patterns are explained in terms of the influences of derivational economy, including the option to restrict in situ indefinite noun phrases to singleton indefinites. The symmetry effect observed in child language studies was also observed among the college-aged participants in this study. It is explained in terms of a pragmatic challenge in managing contextual information that invokes an unexpected singleton indefinite interpretation. The results contribute to the understanding of sentence comprehension under conditions of restricted learner access to target language input and underscore the value of seeking correlates of theory-internal derivational economy in language acquisition and use.
Multifunctional robot to maintain boiler water-cooling tubes
Authors: Gao Xueshan , Xu Dianguo , Wang Yan , Pan Huanhuan , Shen Weimin
Published: February 2009

A robot has been developed to maintain boiler water-cooling tubes. This robot has a double tracked moving mechanism, an ash cleaning device, a slag purging device, a tubes' thickness measurement device, a marking device, and a control system. This robot can climb up and down the tube wall. A method for the robot to complete many tasks for boiler maintenance in one process cycle is presented. The mechanism of the robot is described. Especially, a kind of special magnetic block structure is designed to obtain strong adhering force using permanent magnets. Experiments in laboratory and real thermal power station have verified that the robot cannot only climb on the surface of the tube wall smoothly, but also take heavy payloads for boiler maintenance operation.
Knowing more than one can say: The early regular plural
Authors: ZAPF JENNIFER A. , SMITH LINDA B.
Published: February 2009

This paper reports on partial knowledge in two-year-old children's learning of the regular English plural. In Experiments 1 and 2, children were presented with one kind and its label and then were either presented with two of that same kind (A→AA) or the initial picture next to a very different thing (A→AB). The children in A→AA rarely produced the plural. The children in A→AB supplied the singular form of A but children in A→AA did not. Experiment 3 compared the performance of English-speaking and Japanese-speaking children in A→AA with common and novel nouns. The Japanese-speaking children (learning a language without a mandatory plural) supplied the singular form of A but the English-speaking children did not. The findings indicate young children learning English know there is a plural to be learned before they have fully worked out the rules of production or acquired the necessary singular–plural pairs for broad generalization.
Cobordism of Morse maps and its application to map germs
Authors: IKEGAMI KAZUICHI , SAEKI OSAMU
Published: February 2009

Letf:M→S1be a Morse map of a closed manifoldMinto the circle, where a Morse map is a smooth map with only nondegenerate critical points. In this paper, we classify such maps up to fold cobordism. In the course of the classification, we get several fold cobordism invariants for such Morse maps. We also consider a slightly general situation where the source manifoldMhas boundary and the mapfrestricted to the boundary has no critical points. Letg: (Rm, 0) → (R2, 0),m≥ 2, be a generic smooth map germ, where the targetR2is oriented. Using the above-mentioned fold cobordism invariants, we show that the number of cusps with a prescribed index appearing in aC∞stable perturbation ofg, counted with signs, gives a topological invariant ofg.
On the zeros of the second and third Jackson q-Bessel functions and their associated q-Hankel transforms
Authors: ANNABY M. H. , MANSOUR Z. S.
Published: February 2009

We investigate the zeros of q-Bessel functions of the second and third types as well as those of the associated finite q-Hankel transforms. We derive asymptotic relations of the zeros of the q-Bessel functions by comparison with zeros of the theta function. The asymptotics of q-Bessel functions are also given. Zeros of finite q-Hankel transforms of q-summable functions are shown to be real and simple except for a finite number of possible non real zeros. Sufficient conditions are given to guarantee that all zeros are real. We give some applications concerning zeros of combinations of q-Bessel functions.
Flag modules and the hit problem for the Steenrod algebra
Authors: WALKER G. , WOOD R. M. W.
Published: February 2009

The ‘hit problem’ of F. P. Peterson in algebraic topology asks for a minimal generating set for the polynomial algebraP(n) =2[x1,. . .,xn] as a module over the Steenrod algebra2. An equivalent problem is to find an2-basis for the subringK(n) of elementsfin the dual Hopf algebraD(n), a divided power algebra, such thatSqk(f)=0 for allk> 0. The Steenrod kernelK(n) is a2GL(n,2)-module dual to the quotientQ(n) ofP(n) by the hit elements+2P(n). A submoduleS(n) ofK(n) is obtained as the image of a family of maps from the permutation moduleFl(n) ofGL(n,2) on complete flags in ann-dimensional vector spaceVover2. We use the Schubert cell decomposition of the flags to calculateS(n) in degrees$d =\sum_{i=1}^n (2^{\lambda_i}-1)$, where λ1> λ2> ⋅⋅⋅ > λn≥ 0. When λn= 0, we define a2GL(n,2)-module map δ:Qd(n) →Q2d+n−1(n) analogous to the well-known isomorphismQd(n) →Q2d+n(n) of M. Kameko. When λn−1≥ 2, we show that δ is surjective and δ*:S2d+n−1(n)→Sd(n) is an isomorphism.
Polymyalgica rheumatica and giant cell arteritis
Authors: Bird H A , Mac Iver Helen
Published: February 2009

Polymyalgia rheumatica and giant cell arteritis are closely related conditions, considered by many to represent opposite poles of a single disease spectrum. They can occur together or separately.

Polymyalgia rheumatica is characterized by pain and morning stiffness in the shoulder girdle and sometimes the pelvic girdle. The symptoms are felt to be related to synovitis of proximal joints and extra-articular synovial structures. Giant cell arteritis displays a frank vasculitis affecting the regions supplied by the temporal artery to give visual loss and scalp tenderness but is increasingly recognized to also affect the aorta and its extra-cranial branches. For this reason the term ‘giant cell arteritis’, which is descriptive of the pathology, is used instead of the alternative term ‘temporal arteritis’, which gives a misleading impression of localization but which was the term used in previous reviews for this journal, the most recent in 2003.
The role of interventional radiology in palliative care of malignant disease
Authors: Cope Lance , Wynne Hilary
Published: February 2009

Providing symptomatic palliation in terminal malignant disease is integral to high-quality elderly-care medicine. Effective pharmacological treatment, especially pain relief, is the mainstay of palliative care, but physical intervention is sometimes required to relieve mechanical problems. Interventional radiology is rapidly evolving and there are many clinical situations in which it is indicated. It is as effective as open surgery, but without the risk of general anaesthesia and surgical morbidity. Most interventional radiology procedures can be performed with a much shorter hospital stay than the alternative surgical procedure, and often as a day case admission. Reducing hospital stay and recovery time is of great importance to the older patient who may have a short life expectancy because of the cancer and co-morbidities.