bluuebunny/crossref_metadata_2025 huggingface dataset:
Adult scoliosis: A personal experience
Authors: Reeder Jean M
Published: May 2007

My thoughts were far from the road as I drove away from my appointment with an orthopedic surgeon. He had recommended a posterior spinal fusion to correct my scoliosis. I was confronted with the reality that my busy organized life as a wife and military nurse would be disrupted. Roles would be reversed. I would soon be a patient facing a major surgical procedure and lengthy recovery. I anticipated this experience with much anxiety. It offered, however, the potential for personal and professional growth. I focused on this as a coping mechanism and as a means to channel my increasing anxiety.

As a result of my firsthand surgical experience, I was to find my perceptions about nursing care altered and my commitment to caring strengthened.
Fundamental techniques of plastic surgery and their surgical application
Authors: Crawford Mabel
Published: May 2007

Ian A McGregor, Fundamental techniques of plastic surgery and their surgical application, ed 4, 1969, The Williams & Wilkins Co., Baltimore, 298, $9.25.
THE TRAIN IS COMING
Authors: Seifert Patricia C.
Published: May 2007

THE TRAIN IS COMING, Gladsy Humphries Burriss, 1993, 253, $14.95 hardcover
NEUROSCIENCE NURSING
Authors: McEwen Donna
Published: May 2007

Ellen Barker, NEUROSCIENCE NURSING, 10, 1994, 816, $51.95 hardcover
Current topics include continuing education, legal issues
Authors: Edwards Mary Jane C.
Published: May 2007

Current topics include continuing education, legal issues: Legal Issues in Nursing. Cynthia E. Northrop, Mary E. Kelly. C V Mosby Co, 11830 Westline Industrial Dr, St Louis, MO 63146, 1987, 598 pp, $25.95 paperback.
Davis's Drug Guide for Nurses
Authors: Pawlowski Jacqueline
Published: May 2007

Davis's Drug Guide for Nurses: By Judith H. Deglin, April H. Vallerand 1988, 739 pp $18.95 clothbound
Understanding ethical issues, psychiatric needs of patient care: Computerized Nursing Care Planning Utilizing Nursing Diagnosis: A Handbook.
Authors: Latz Paula Anne
Published: May 2007

Joan M. Crosley, Computerized Nursing Care Planning Utilizing Nursing Diagnosis: A Handbook, 1975, Oryn Publications, Inc, 2000 L St NW, Washington, DC 20036, 219, $19.95 paperback.
Fundamentals of Surgery
Authors: Alverson Elise M.
Published: May 2007

Fundamentals of Surgery, sixth ed. By Richard D. Liechty, Robert T. Soper 1989, 648 pp $39.95 paperback
Nursing Leadership and Management: Concepts and Practice
Authors: Owen Charlotte H.
Published: May 2007

Nursing Leadership and Management: Concepts and Practice, second ed. By Ruth M. Tappen 1989, 532 pp $23.95 paperback
Synopsis of Common Surgical Procedures
Authors: Torresyap Pearl M.
Published: May 2007

Synopsis of Common Surgical Procedures By Balazs Imre Bodai 1993, 345 pp $29.95 paperback
The Complete Recovery Room Book
Authors: Miehl Jann L.
Published: May 2007

The Complete Recovery Room Book By Anthea Hatfied, Michael Tronson 1992, 384 pp $80 hardcover, $35 paperback
THE GENERALIZED HOMOLOGY OF PRODUCTS
Authors: HOVEY MARK
Published: May 2007

We construct a spectral sequence that computes the generalized homology E*(∏ Xα) of a product of spectra. The E2-term of this spectral sequence consists of the right derived functors of product in the category of E*E-comodules, and the spectral sequence always converges when E is the Johnson-Wilson theory E(n) and the Xα are Ln-local. We are able to prove some results about the E2-term of this spectral sequence; in particular, we show that the E(n)-homology of a product of E(n)-module spectra Xα is just the comodule product of the E(n)*Xα. This spectral sequence is relevant to the chromatic splitting conjecture.
RECURRENCE RELATIONS, DYNKIN DIAGRAMS AND PLÜCKER FORMULAE
Authors: BURNS JOHN M. , CLANCY MICHAEL J.
Published: May 2007

We prove a generalisation of an observation of N. Iwahori concerning the coefficients of the extended Dynkin diagram of a complex simple Lie algebra. We relate the combinatorics of these coefficients to the orders of finite groups that act discontinuously on the Riemann sphere and to the Plücker formulae.
GROUP EXTENSIONS AND THE PRIMITIVE IDEAL SPACES OF TOEPLITZ ALGEBRAS
Authors: ADJI SRIWULAN , RAEBURN IAIN , ROSJANUARDI RIZKY
Published: May 2007

Let Γ be a totally ordered abelian group andIan order ideal in Γ. We prove a theorem which relates the structure of the Toeplitz algebraT(Γ) to the structure of the Toeplitz algebrasT(I) andT(Γ/I). We then describe the primitive ideal space of the Toeplitz algebraT(Γ) when the set Σ(Γ) of order ideals in Γ is well-ordered, and use this together with our structure theorem to deduce information about the ideal structure ofT(Γ) when 0→I→ Γ→ Γ/I→ 0 is a non-trivial group extension.
ON THE FREE SPECTRUM OF THE VARIETY GENERATED BY THE COMBINATORIAL COMPLETELY 0-SIMPLE SEMIGROUPS
Authors: KÁTAI-URBÁN KAMILLA , SZABÓ CSABA
Published: May 2007

We give an asymptotic bound for the size of the n-generated relatively free semigroup in the variety generated by all combinatorial strictly 0-simple semigroups.
SOME PROPERTIES OF CLASS A(k) OPERATORS AND THEIR HYPONORMAL TRANSFORMS
Authors: MARY J. STELLA IRENE , PANAYAPPAN S.
Published: May 2007

In this paper we shall first show that if T is a class A(k) operator then its operator transform $\hat{T}$ is hyponormal. Secondly we prove some spectral properties of T via $\hat{T}$. Finally we show that T has property (β).
BOUNDED LINEAR OPERATORS ON SPACES IN NORMED DUALITY
Authors: BARNES BRUCE A.
Published: May 2007

LetTbe a bounded linear operator on a Banach spaceW, assumeWandYare in normed duality, and assume thatThas adjointT†relative toY. In this paper, conditions are given that imply that for all λ≠0, λ−Tand λ −T†maintain important standard operator relationships. For example, under the conditions given, λ −Thas closed range if, and only if, λ −T†has closed range.

These general results are shown to apply to certain classes of integral operators acting on spaces of continuous functions.
Experimental and numerical studies of magnetoconvection in a rapidly rotating spherical shell
Authors: GILLET N. , BRITO D. , JAULT D. , NATAF H. C.
Published: May 2007

Thermal magnetoconvection in a rapidly rotating spherical shell is investigated numerically and experimentally in electrically conductive liquid gallium (Prandtl number P = 0.025), at Rayleigh numbers R up to around 6 times critical and at Ekman numbers E ∼ 10−6. This work follows up the non-magnetic study of convection presented in a companion paper (Gillet et al. 2007). We study here the addition of a z-invariant toroidal magnetic field to the fluid flow. The experimental measurements of fluid velocities by ultrasonic Doppler velocimetry, together with the quasi-geostrophic numerical simulations incorporating a three-dimensional modelling of the magnetic induction processes, demonstrate a stabilizing effect of the magnetic field in the weak-field case, characterized by an Elsasser number Λ < (E/P)1/3. We find that this is explained by the changes of the critical parameters at the onset of convection as Λ increases. As in the non-magnetic study, strong zonal jets of characteristic length scales ℓβ (Rhines length scale) dominates the fluid dynamics. A new characteristic of the magnetoconvective flow is the elongation of the convective cells in the direction of the imposed magnetic field, introducing a new length scale ℓφ. Combining experimental and numerical results, we derive a scaling law $\overline{U} \,{\sim}\, (\widetilde{U}_s \widetilde{U}_{\phi})^{2/3} \,{\sim}\, \widetilde{U}_s{}^{4/3} (\ell_{\phi}/\ell_{\beta})^{2/3}$ where U is the axisymmetric motion amplitude, Ũs and Ũφ are the non-axisymmetric radial and azimuthal motion amplitudes, respectively.
Inviscid and viscous aerodynamics of dense gases
Authors: CINNELLA PAOLA , CONGEDO PIETRO M.
Published: May 2007

A numerical investigation of transonic and low-supersonic flows of dense gases of the Bethe–Zel'dovich–Thompson (BZT) type is presented. BZT gases exhibit, in a range of thermodynamic conditions close to the liquid/vapour coexistence curve, negative values of the fundamental derivative of gasdynamics. This can lead, in the transonic and supersonic regime, to non-classical gasdynamic behaviours, such as rarefaction shock waves, mixed shock/fan waves and shock splitting. In the present work, inviscid and viscous flows of a BZT fluid past an airfoil are investigated using accurate thermo-physical models for gases close to saturation conditions and a third-order centred numerical method. The influence of the upstream kinematic and thermodynamic conditions on the flow patterns and the airfoil aerodynamic performance is analysed, and possible advantages deriving from the use of a non-conventional working fluid are pointed out.
On the thermal buffering of naturally ventilated buildings through internal thermal mass
Authors: HOLFORD J. M. , WOODS A. W.
Published: May 2007

In this paper we examine the role of thermal mass in buffering the interior temperature of a naturally ventilated building from the diurnal fluctuations in the environment. First, we show that the effective thermal mass which is in good thermal contact with the air is limited by the diffusion distance into the thermal mass over one diurnal temperature cycle. We also show that this effective thermal mass may be modelled as an isothermal mass. Temperature fluctuations in the effective thermal mass are attenuated and phase-shifted from those of the interior air, and therefore heat is exchanged with the interior air. The evolution of the interior air temperature is then controlled by the relative magnitudes of (i) the time for the heat exchange between the effective thermal mass and the air; (ii) the time for the natural ventilation to replace the air in the space with air from the environment; and (iii) the period of the diurnal oscillations of the environment. Through analysis and numerical solution of the governing equations, we characterize a number of different limiting cases. If the ventilation rate is very small, then the thermal mass buffers the interior air temperature from fluctuations in the environment, creating a near-isothermal interior. If the ventilation rate increases, so that there are many air changes over the course of a day, but if there is little heat exchange between the thermal mass and interior air, then the interior air temperature locks on to the environment temperature. If there is rapid thermal equilibration of the thermal mass and interior air, and a high ventilation rate, then both the thermal mass and the interior air temperatures lock on to the environment temperature. However, in many buildings, the more usual case is that in which the time for thermal equilibration is comparable to the period of diurnal fluctuations, and in which ventilation rates are moderate. In this case, the fluctuations of the temperature of the thermal mass lag those of the interior air, which in turn lag those of the environment. We consider the implications of these results for the use of thermal mass in naturally ventilated buildings.
Centrifugal effects in rotating convection: axisymmetric states and three-dimensional instabilities
Authors: MARQUES F. , MERCADER I , BATISTE O. , LOPEZ J. M.
Published: May 2007

Rotating convection is analysed numerically in a cylinder of aspect ratio one, for Prandtl number about 7. Traditionally, the problem has been studied within the Boussinesq approximation with density variation only incorporated in the gravitational buoyancy term and not in the centrifugal buoyancy term. In that limit, the governing equations admit a trivial conduction solution. However, the centrifugal buoyancy changes the problem in a fundamental manner, driving a large-scale circulation in which cool denser fluid is centrifuged radially outward and warm less-dense fluid is centrifuged radially inward, and so there is no trivial conduction state. For small Froude numbers, the transition to three-dimensional flow occurs for Rayleigh number R ≈ 7.5 × 103. For Froude numbers larger than 0.4, the centrifugal buoyancy stabilizes the axisymmetric large-scale circulation flow in the parameter range explored (up to R = 3.5 × 104). At intermediate Froude numbers, the transition to three-dimensional flow is via four different Hopf bifurcations, resulting in different coexisting branches of three-dimensional solutions. How the centrifugal and the gravitational buoyancies interact and compete, and the manner in which the flow becomes three-dimensional is different along each branch. The centrifugal buoyancy, even for relatively small Froude numbers, leads to quantitative and qualitative changes in the flow dynamics.
Periodic intrusions in a stratified fluid
Authors: KERR OLIVER S.
Published: May 2007

When a salt-stratified body of fluid is heated from the side a series of almost horizontal convective layers can develop with well-mixed interiors. These layers can propagate into the interior of the stratified fluid. This behaviour is also observed with intrusions at fronts between stratified bodies of fluid where their composition varies. We look at a simplified model of intrusion growth where the mechanism behind the creation of their well-mixed interiors is neglected, and look at how a stack of such intrusions will propagate away from the wall or front. We find that there is a transition from a regime where the propagation is essentially inviscid and the intrusion length is proportional to time, to one where viscosity is important and the propagation rate slows down, with the length being proportional to the square-root of time.
On the large-scale structure of homogeneous two-dimensional turbulence
Authors: DAVIDSON P. A.
Published: May 2007

We consider freely decaying two-dimensional isotropic turbulence. It is usually assumed that, in such turbulence, the energy spectrum at small wavenumber, k, takes the form E(k → 0) ∼ Ik3, where I is the two-dimensional version of Loitsyansky's integral. However, a second possibility is E(k → 0) ∼ Lk, where the pre-factor, L, is the two-dimensional analogue of Saffman's integral. We show that, as in three dimensions, L is an invariant and that E ∼ Lk spectra arise whenever the eddies possess a significant amount of linear impulse. The conservation of L is shown to be a direct consequence of the principle of conservation of linear momentum. We also show that isotropic turbulence dominated by a cloud of randomly located monopole vortices has a singular energy spectrum of the form E(k → 0) ∼ Jk−1, where J, like L, is an invariant. However, while E ∼ Jk−1 necessarily implies the existence of a sea of monopoles, the converse need not be true: a sea of monopoles whose spatial locations are not entirely random, but constrained in some way, need not give a E ∼ Jk−1 spectra. The constraint imposed by the conservation of energy is particularly important, ruling out E ∼ Jk−1 spectra for certain classes of initial conditions. Finally, we provide simple explicit examples of random vorticity fields with E ∼ Ik3, E ∼ Lk and E ∼ Jk−1 spectra.
A formulation of convective entrainment in terms of mixing efficiency
Authors: CHEMEL C. , STAQUET C.
Published: May 2007

The entrainment across a stably stratified interface forced by convective motions is discussed in the light of the mixing efficiency of the entrainment process. The context is the convectively driven atmospheric boundary layer and we focus on the regime of equilibrium entrainment, i.e. when the boundary-layer evolution is in a quasi-steady state. The entrainment law is classically based on the ratio R of the negative of the heat flux at the interface to the heat flux at the ground surface. We propose a parameterization for R that involves the mixing efficiency and the thickness of the interface, which matches well the direct computation of R from a high-resolution large-eddy simulation. This result enables us to derive modified expressions for the classical entrainment laws (the so-called zero- and first-order models) as a function of the mixing efficiency. We show that, when the thickness of the interface is ignored (zero-order model), the scaling factor A in the entrainment law is the flux Richardson number. This parameterization of A is further improved when the thickness of the interface is considered (first-order model), as shown by the direct computation of A from the large-eddy simulation.
Lichenostigma svandae, a new lichenicolous fungus on Acarospora cervina
Authors: VONDRÁK Jan , ŠOUN Jaroslav
Published: May 2007

The new species Lichenostigma svandae is described. It is known exclusively from Acarospora cervina, where it forms black stromatic hyphal strands and black sack-shaped ascomata on the host thallus surface. It is similar to L. elongatum and L. rouxii, but differs in a few characters. A short overview of the known Lichenostigma species is provided.
The lichen Fuscopannaria leucosticta (Tuck.) P. M. Jørg. found in the tropics
Authors: Jørgensen Per M. , Sipman Harrie J. M.
Published: May 2007

In a recent treatment of the Pannariceae of Ecuador, Jørgensen & Arvidsson (2004: 131) pointed out the surprising absence of the genus Fuscopannaria in Ecuador, a genus which is rather common, with many species, in the Pacific Northwest of North America (Jørgensen 2001). The authors claim that, on the western side of the Americas, the genus appears to stop north of Mexico, only to reappear in southern Chile and Argentina. While going through his material, the second author discovered two specimens belonging in this genus from Mexico and Ecuador, which contradicts that statement. Both are typical Fuscopannaria leucosticta specimens (Fig. 1), the type species of the genus originally described from eastern North America (Jørgensen 2001: 684), and fairly widely distributed in warm temperate parts there, and extending as far south as Cuba (Fig. 2).
Xanthoparmelia pseudohungarica in Spain
Authors: Pérez-Ortega Sergio , Elix John A.
Published: May 2007

The genus Xanthoparmelia (Vain.) Hale (including Neofuscelia Essl.) currently includes more than 800 species (Blanco et al. 2004, 2005), 21 of which have been recorded in the Iberian Peninsula (Llimona & Hladun 2001). During recent studies of the lichen flora of Castilla y León by the first author, a rare, loosely adnate or vagrant, terricolous Xanthoparmelia has been found at two localities in Burgos province. Although a collection (VAL-Lich 20080) from one of the localities (Fresnillo de las Dueñas) was previously reported as the American species X. vagans (Nyl.) Hale (Pérez-Ortega et al. 2002), this collection has now been redetermined as X. pseudohungarica (Gyeln.) Hale.
A second species of Lithographa with submuriform ascospores
Authors: FRYDAY Alan M. , COPPINS Brian J.
Published: May 2007

The new combination Lithographa skottsbergii (Zahlbr.) Fryday & Coppins is made for Enterostigma skottsbergii Zahlbr., described from the Juan Fernandez Islands off the coast of Chile. The species is known only from Chile but its geographical range is here extended to include maritime regions of south-west Chile. The distribution pattern of the Lithographa species with submuriform ascospores is also discussed.
New discoveries in Asian pannariaceous lichens
Authors: JØRGENSEN Per M.
Published: May 2007

New collections from inner China have revealed further species in the genus Fuscopannaria: two new species, Fuscopannaria cyanogranulosa P. M. Jørg. and Fuscopannaria obtegens P. M. Jørg. are described and Fuscopannaria subgemmascens Upreti & Divakar is reported as new to Sichuan. A key to the sorediate species of the region is provided. The first fertile specimen of Kroswia gemmascens has been discovered, much further west than previously known, showing the genus to be related most closely to Fuscopannaria despite its gelatinous, homoiomerous thallus. Some collections from the Mulu region in Borneo have added to our knowledge of the difficult lowland taxa of Parmeliella, two of which proved to be new: Parmeliella plumosella P. M. Jørg. and Parmeliella polydactyla P. M. Jørg. & Coppins, both being quite unusual in containing “violet” Nostoc as cyanobiont. There is a surprising number of Asian collections with brightly coloured medullas: red-orange material has been named several times and is correctly referred to as Parmeliella endomilta Vain. The specimens with a yellow medulla are named Parmeliella endolutea P. M. Jørg., nom. nov. A key to the brightly coloured species of Parmeliella concentrated in SE Asia is given. A new corticolous Protopannaria has been discovered in Sichuan, and is described as P. corticola P. M. Jørg.
Imputed Criminal Liability and the Goals of International Justice
Authors: DARCY SHANE
Published: May 2007

This article considers the suitability of employing particular modes of imputed criminal liability in trials before international criminal tribunals. It focuses specifically on the doctrines of joint criminal enterprise and superior responsibility, two forms of liability which are central to many contemporary international criminal proceedings. Both doctrines can involve a broad form of criminal liability which may not be entirely appropriate when one considers the context in which such trials take place and the significance which often attaches to them. Proponents of international justice have contended that the contribution of these trials goes beyond basic accountability and providing justice for victims, extending also to peacemaking, reconciliation, deterrence, and the creation of a historical record. This article queries whether aspects of joint criminal enterprise liability and superior responsibility are appropriate when international justice is viewed in this light.
Unequal before the Law: The Case for the Elimination of the Distinction between International and Non-international Armed Conflicts
Authors: CRAWFORD EMILY
Published: May 2007

This article examines the possibility of creating a law of armed conflict that could be uniformly applied to both international and non-international armed conflict. The article looks at the history of modern armed conflict, and charts the progression of warfare from a predominantly interstate event to that which is more likely to be characterized as non-international or internal. The increasing prevalence of non-international armed conflicts throughout the twentieth century has lead to ongoing moves on behalf of the international community to bring the regulation of such conflicts further within the ambit of international regulation. With this in mind, the article argues that such moves have blurred the historical distinction between types of armed conflict to the point where the distinction could be eliminated altogether. By looking at international treaties, tribunals, and state practice, this article asserts that the law of armed conflict could be uniformly applied, with the aim of ensuring that all participants in armed conflict are equally and humanely treated.
On the Scope of Professional Secret and Confidentiality: The International Criminal Court Code of Professional Conduct for Counsel and the Lawyer's Dilemma
Authors: AFIFI ABDELRAHMAN
Published: May 2007

In late 2005 the Assembly of States Parties adopted the Code of Professional Conduct for Counsel of the International Criminal Court. Article 22 of the Code contains a provision on fee splitting which does not go as far as to place a positive duty on counsel to report such practices to the Registrar. This essay revisits this approach in the light of the practice of the ad hoc tribunals, the jurisprudence of the European Court of Human Rights, and existing norms in domestic legislation. It argues that the lawyer–client privilege is not absolute. Accordingly, the ICC should make it obligatory – through specific empowering clauses – for lawyers to advise their clients about the prohibition of the practice of fee splitting and to report the incident to the Registrar forthwith, notwithstanding any claim of privilege.
Radiative transfer modeling of the Hanle effect in convective atmospheres
Authors: Bueno Javier Trujillo
Published: May 2007

This paper summarizes the results of a recent investigation on the Hanle effect in atomic and molecular lines, which indicates that there is a vast amount of “hidden” magnetic energy and (unsigned) magnetic flux in the internetwork regions of the quiet solar photosphere. This hidden magnetic energy, localized in the (intergranular) downflowing plasma of the solar photosphere, is carried mainly by tangled fields at sub-resolution scales with strengths between the equipartition field values and ∼1 kG, and is more than sufficient to compensate the radiative energy losses of the solar outer atmosphere.
Round table discussion of session A: modelling convection and radiative transfer
Authors: Kupka F.
Published: May 2007

A summary of the round table discussion following Session A on Modelling Convection and Radiative Transfer is provided based on the video recording made during the conference.
Modelling of solar granulation
Authors: Muthsam H. J. , Löw-Baselli B. , Obertscheider Chr. , Langer M. , Lenz P. , Kupka F.
Published: May 2007

We present the essential features of the ANTARES code. ANTARES has been developed to perform the simulation of astrophysical flows in one, two, or three dimensions. Using, in particular, the option of grid refinement, we present results for solar granulation achieved at very high spatial resolution.
Observing convection in stellar atmospheres
Authors: Landstreet John D.
Published: May 2007

Convection occurs in the visible photospheric layers of most stars having Te less than about 10000 K, and in some hotter stars. The solar granulation pattern is a symptom of this, as is the non-zero microturbulent velocity often required in abundance analysis to make both weak and strong lines yield the same abundance.

In very sharp-lined stars, the presence of a non-thermal velocity field in the visible stellar atmosphere leads to several other effects which may be detected in spectral line profiles. These include radial velocities that vary systematically with equivalent width, distortions of the line profile as compared to a profile computed with a Voigt profile and rotational broadening (“macroturbulence”), and asymmetries with respect to the line centre (“bisector curvature”).

Detection and interpretation of these effects, with the goal of obtaining empirical information about a velocity field present in the visible layers, requires comparison with calculated synthetic spectra which incorporate model velocity fields. Thus, this review will summarize some of the observational clues concerning photospheric velocity fields, as well as modelling aimed at interpreting these data.
Round table discussion of session B: observational probes of convection
Authors: Smalley Barry
Published: May 2007

A summary of the round table discussion following Session B on Observational Probes of Convection.
Stellar fluxes as probes of convection in stellar atmospheres
Authors: Smalley Barry
Published: May 2007

Convection and turbulence in stellar atmospheres have a significant effect on the emergent flux from late-type stars. The theoretical advancements in convection modelling over recent years have proved challenging for the observers to obtain measurements with sufficient precision and accuracy to allow discrimination between the various predictions. An overview of the current observational techniques used to evaluate various convection theories is presented, including photometry, spectrophotometry, and spectroscopy. The results from these techniques are discussed, along with their successes and limitations. The prospects for improved observations of stellar fluxes are also given.
On the relation between rotation, convection and activity in intermediate-mass giants
Authors: Gondoin P.
Published: May 2007

I found evidence that the X-ray surface flux of intermediate-mass G and K giants is correlated with their rotation period and Rossby number. Confidence in the degree of correlation is significantly higher when stellar gravity is taken into account. An empirical relation is found that accounts for the X-ray luminosity evolution of single intermediate-mass giants and giants in close or long-period binary systems, such as RS CVn-type systems, as they evolve off the main sequence towards the top of red giant branch.
Microturbulent velocities and abundances for A and F dwarfs in open clusters
Authors: Gebran M. , Monier R.
Published: May 2007

The current status of microturbulent velocity and abundance determinations for A and F dwarfs in open clusters is reviewed. A programme to observe several tens of A and F dwarfs in open clusters of various ages was initiated several years ago. We have performed high resolution high signal-to-noise spectroscopy of stars well distributed in mass along the Main Sequence. Microturbulent velocities and abundances of several chemical elements have been derived iteratively by fitting grids of synthetic spectra calculated in LTE to the observed spectra. Curve of growths were used in a few instances as well. The results obtained are reviewed for Coma Berenices, the Pleiades, Alpha Persei and the Ursa Major moving group.

The microturbulent velocities exhibit a broad maximum in the range A5V to about F0V as indicated in Smalley (2004).
Observations of convection in the giant planets: results from space missions
Authors: Ingersoll A. P.
Published: May 2007

The giant planets are fluid objects; their solid cores occupy much less than half of their volumes. The largest planet, Jupiter, is over ten times the size of Earth. The giant planet atmospheres are powered in roughly equal parts by sunlight and by internal heat, which is left over from planetary formation. In most cases, the winds are measured by tracking clouds relative to the internal magnetic fields. Saturn is the exception, since the internal field is axisymmetric and therefore provides no evidence of rotation. In all four giant planets, the winds blow mainly in the east-west (zonal) direction, and the coloured cloud bands are aligned with the winds. The patterns are organized by rotation and not by the energy sources, since the sun at zenith moves from one pole to the other during the course of a year on Uranus, and yet the winds do not change. Although the power per unit area - the sum of absorbed sunlight and internal heat - is 20 times greater at Jupiter than at Neptune, the winds at Neptune are stronger. In fact Jupiter has the weakest winds of all the giant planets, although it is closest to the sun. Besides the zonal winds, the giant planets have long-lived vortices that have the same sign of vorticity as the latitude bands in which they sit. These large vortices exhibit a variety of behaviours, including oscillation in shape, position, and orientation, merging and splitting, and filament ejection. The anticyclones have a compact, oval shape; the cyclones are more elongated and diffuse. The cyclones contain lightning, which is a sign of moist convection. The cyclones therefore have a more disturbed appearance, since the convective storms are vigorous and chaotic. The convective storms are more frequent on Jupiter, but they are apparently more energetic on Saturn. The convective storms maintain a Reynolds stress that pumps momentum into the zonal jets in what is known as an inverse energy cascade. The depth to which the zonal winds extend is largely unknown. The winds could be confined to the outer 1 percent of the planets radii, or they could extend down into the fluid interiors, where the electrical conductivity and magnetic field become important.
Convection in brown dwarfs
Authors: Mohanty Subhanjoy , Baraffe Isabelle , Chabrier Gilles
Published: May 2007

We briefly review the crucial effect that convection plays in the evolution, interior and atmospheric physics of brown dwarfs. In particular, we discuss: (1) the role of convection in the interior structure and evolution of brown dwarfs (BDs); (2) the importance of convection in the atmospheres of ultra-cool objects, at both high and low gravities (i.e., in both young and old BDs); and (3) the role of convection/turbulence in the formation and settling of dust grains, and non-equilibrium chemistry, in BD atmospheres.
Convection during the formation of gaseous giants and stars
Authors: Wuchterl Günther
Published: May 2007

Convection theories for star and planet formation studies have to be (1) simple, to allow a self-consistent solution with other relevant processes, (2) time-dependent, because convection often starts in collapse-flows, and (3) robust, i.e. physically well-behaved under a wide range of conditions ranging from the quiet protoplanetary nebula to supercritical protostellar accretion-shocks with Mach-numbers of a few hundred. I describe how the equations of radiation fluid-dynamics can be augmented by a one-equation convection model in order to construct a system of equations that contains the Sun, brown dwarfs and planets as well as their nearly isothermal parent-clouds. The system of equations is calibrated to the Sun and tested by the solar convection zone and the pulsations of RR-Lyrae stars. I discuss the following applications: (1) star formation as the collapse of Bonnor-Ebert spheres of masses ranging from the stellar domain to the brown dwarf region, (2) the approach to the main sequence, (3) companion mass determinations for direct imaging searches for exoplanets, with GQ Lupi as an example, and (4) the formation of Pegasi-planets, and the “large core” exoplanet, HD 149 026, in particular.
Round table discussion of session C: convection in planets and brown dwarfs
Authors: Chan Kwing L.
Published: May 2007

The following is an edited excerpt of the DVD recording of Session C's Round Table Discussion. Due to the tight publication schedule, participants have not been given much time to review its contents in detail. There may be unclear and inaccurate spots, but it should give an illustrative description of the dynamics of the interesting discussions.
Chemical composition of dust clouds in turbulent brown dwarf atmospheres
Authors: Helling Christiane
Published: May 2007

Brown dwarf atmospheres are largely convective. These convective gas flows collide and feed back a whole spectrum of turbulent fluctuations into the atmospheric fluid field. Resulting non-static density and temperature fields influence the local chemistry concerning gas phase and dust formation. Numerical simulations are used to show the large and inhomogeneous changes of the gas phase chemistry in a turbulent dust forming cloud region of a brown dwarf atmosphere. The relaxation time scale of the gas phase composition towards steady state is considerably longer than for the dust component.
The influence of convective energy transport on dust formation in brown dwarf atmospheres
Authors: Dehn Matthias , Helling Christiane , Woitke Peter , Hauschildt Peter
Published: May 2007

Convection is the main energy transport mechanism in brown dwarf atmospheres. The overshoot of ascending bubbles affects the upper and cooler region where dust formation can occur. In order to understand the observed presence of dust, the formation of grains and their gravitational settling must be balanced by up-mixing of condensible elements via convective overshoot. Otherwise, brown dwarf atmospheres would be completely dust-free (Woitke & Helling 2004).
A finite-difference convective model for Jupiter's equatorial jet
Authors: Chan Kwing L.
Published: May 2007

We present results of a numerical model for studying the dynamics of Jupiter's equatorial jet. The computed domain is a piece of spherical shell around the equator. The bulk of the region is convective, with a thin radiative layer at the top. The shell is spinning fast, with a Coriolis number = ΩL/V on the order of 50. A prominent super-rotating equatorial jet is generated, and secondary alternating jets appear in the higher latitudes. The roles of terms in the zonal momentum equation are analyzed. Since both the Reynolds number and the Taylor number are large, the viscous terms are small. The zonal momentum balance is primarily between the Coriolis and the Reynolds stress terms.
Stellar convection with nuclear burning
Authors: Arnett David , Meakin Casey , Young Patrick A.
Published: May 2007

Careful choice of of method, problem, and zoning has allowed us to do three-dimensional (3D) simulations of thermally relaxed, nearly adiabatic convection (with nuclear burning). The simulations are run long enough so that a robust statistical state is found. We find that 2D simulations are biased relative to 3D simulations: 2D shows larger velocities and less mixing than their 3D counterparts. Detailed theoretical analysis of these numerical experiments allows us to begin to build a simple theoretical model of turbulent convection in stars, which may be used in 1D calculations of stellar evolution. Implications for stellar evolution, will be discussed. Oxygen shell burning simulations in 3D, and multishell burning of C, Ne, O, and Si in 2D will be presented, as will aspherical distortion in supernovae progenitors (Meakin and Arnett, 2006a). Contact will be made with convective driving of waves, convective zone growth by entrainment, the velocity scale and the geometric parameters in mixing length theory, and the solar Ne abundance problem. Explicit comparisons of compressible and anelastic methods at modest Mach numbers (M≈ 0.01 to 0.1), as well as solutions of the nonradial wave equations, are presented here. Additional detail is presented in the poster by Meakin.
On supersonic convection in stellar atmospheres
Authors: Xiong D. R. , Deng L.
Published: May 2007

It follows from the local mixing length theory that the convection in the atmospheres of yellow and red giants and super-giants become supersonic. In this work we studied the physical reality of such phenomenon and its possible consequences on the structure and evolution of stars involving such situations. The main conclusion is that the supersonic nature of convection as predicted by the local mixing length theory has been overestimated. If supersonic convection is not an artifact in all situations, it is the case at least for all yellow giants and super-giants. We believe that such an artifact is due to the imperfect of the mixing length theory. Owing to the fact that convective energy transport in the atmospheres of yellow giants and super-giants is quite negligible, these artifacts have very limited consequences on the structure and evolution of these stars. However, it is not the case for red giants and super-giants whose properties can be seriously affected by this overestimation. Our investigation shows that the theoretical red phases of stars under consideration are somewhat too blue as predicted with the usual mixing length theory. To this aim, full hydrodynamic simulation is needed in order to clear the doubts on the existence of supersonic convection in these red objects.
Abundances in extremely metal-poor stars: comparison of the trends of abundance ratios in giants and turnoff stars
Authors: Spite Monique , Bonifacio Piercarlo , Cayrel Roger , Spite François , Hill Vanessa , Andersen Johannes , Barbuy Beatriz , Beers Timothy , Depagne Eric , François Patrick , Molaro Paolo , Nordström Birgitta , Plez Bertrand , Primas Francesca
Published: May 2007

We show that in a sample of Extremely Metal-Poor (EMP) giants (<[Fe/H]>=−3.1) all the stars with a luminosity higher than logL/L⊙ ≈ 2.6 present the characteristics of a mixing of the surface with the H-burning layer: low abundance of carbon and high abundance of nitrogen. In these “mixed stars” the lithium abundance and the ratio 12C/13C are very low. Some of these stars are also Na or/and Al rich.
CNO and Li abundances in Barium-enriched stars
Authors: Drake Natalia A. , Pereira Claudio B.
Published: May 2007

CNO and Li abundances and 12C/13C isotopic ratios have been derived for two metal-poor Ba giants, HD 104340 and HD 206983, and two CH subgiants, HD 50264 and HD 87080. High resolution spectra obtained with the 1.52 m telescope and the FEROS echelle spectrograph at ESO, La Silla, Chile, were used in this study. CNO and Li abundances so as 12C/13C isotopic ratios were determined by applying the synthetic spectrum method to the lines of C2, CH, CN, [O I’ and Li I. Our analysis showed that the giant stars studied here have quite different natures: HD 206983 is a metal-poor barium star while HD 104340, although showing enhancement of s-process elements, should not be considered as a classical barium star: its barium syndrome can be explained by internal nucleosynthesis. The low metallicity giant HD 104340 can experience deeper convective mixing and, consequently, a larger dredge-up of CNO-cycle products compared to normal red giants. Light element abundance pattern of HD 104340 resembles anomalies resulting from the appearance on the stellar surface of material enriched in triple-α and CNO cycling.
Rotational properties of the Orion nebular cluster revised
Authors: Landin Natália R. , Ventura Paolo , D'Antona Francesca , Mendes Luiz T. S. , Vaz Luiz P. R.
Published: May 2007

The observational data of the Orion Nebula Cluster (ONC) is reanalyzed by means of new sets of pre-main sequence (PMS) evolutionary tracks including rotation, non-gray boundary conditions (BC's) and either low (LCE) or high convection efficiency (HCE), aiming better understanding of the appropriate physical constraints for the rotational evolution of the stars within the ONC. The role played by convection is a key aspect of our analysis, since there are conflicting results from theory and observations. We derived stellar masses and ages for the ONC by using both LCE and HCE and considered was the role of non-gray atmospheres. Our results show that the resulting mass distribution for the bulk of the ONC population is in the range 0.2-0.4M⊙ for our non-gray models, and in the range 0.1-0.3M⊙ for gray models. In agreement with previous works, we found that a large percentage (∼70%) of low-mass stars (M≤Mtr, where Mtr is a transition mass) in the ONC appears to be fast rotators (P<4days). Mtr depends on the model choosen, being Mtr=0.5 for LCE, Mtr=0.35 for HCE and, as found in previous works, Mtr=0.25 for gray models. Finally, our analysis indicates that a second parameter is needed for a proper description of convection in the PMS phase.
Numerical simulations of semiconvection
Authors: Bascoul Guillaume P.
Published: May 2007

Using a semiconvective model based on thermohaline convection, we investigate the case of an expanding core of a main-sequence massive star. The numerical simulations at high Prandtl number show a flow consistent with the assumption that a dynamically neutral layer sits between the core and the radiative envelope. More simulations at low Prandtl number are needed to infer scaling laws applicable to astrophysical regimes.
Application of convection simulations to oscillation excitation and local helioseismology
Authors: Stein Robert F. , Benson David , Georgobiani Dali , Nordlund Åke
Published: May 2007

Excitation of f- and p- modes by Reynolds stresses and entropy fluctuations is reviewed. Approximations made to allow semi-analytic analysis are discussed. The spectrum of solar convection is presented and shown to NOT be separable into independent spatial and temporal factors. An appropriate fitting formula is presented.

Time-distance local helioseismology has been analyzed using numerical simulations. One approach is simulation of solar surface convection on supergranule scales (48 Mm wide by 20 Mm deep). A surface shear layer develops. There is a continuous increase in the horizontal scale of the convective motions with increasing depth. Some small granular scale downflows at the surface are swept sideways by diverging larger scale upflows from below to merge into stronger downdrafts in these larger downflow boundaries. Elsewhere, some granular downflows have to beat their way against the upflows from below are halted. These simulations have a rich spectrum of f- and p- modes that turn within the computational domain. Cross-correlations between each surface location and each location below the surface reveals the wave propagation pattern from the surface. Waves at the surface that propagate into the interior, spread horizontally and are refracted back toward the surface. Time-distance diagrams have been constructed and inverted to determine the subsurface flows, which can then be compared with the average flows in the simulation.

A second approach calculates the propagation of linearized waves through a fixed, but non-uniform, background state. Some examples of such analysis are presented.
Convection and pulsation in red giant stars
Authors: Wood P. R.
Published: May 2007

Convection strongly influences the periods, stability and amplitudes of pulsation in red giant stars. For example, changing the efficiency of convection (the mixing length parameter) changes the radius and the effective temperature of a red giant, which in turn changes the pulsation period at a given luminosity. Since essentially all the energy flux outside the nuclear-burning core is carried by convection, it is the variation of convective energy transport throughout the pulsation cycle that determines pulsation stability. In both linear and nonlinear pulsation models, the turbulent viscosity that results from the interaction of pulsation with turbulent convection provides a strong damping effect on pulsation and, in nonlinear models, it determines the limiting amplitude. In this paper, these and other topics are discussed.
Round table discussion of session E: oscillations, mass loss and convection
Authors: Goupil Marie-Jo
Published: May 2007

In order to initiate the discussion after the talks of this session, questions such as ‘what seismology can teach us? Which seismic constrains are needed to test stellar modelling and particularly convection?’ have been asked to the audience.
Probing turbulence with seismic observations of α Centauri
Authors: Straka C. W. , Demarque P. , Robinson F. J.
Published: May 2007

We present two 3D Large Eddy Simulations (LES) of the convection-radiation transition layer for both the A and the B component of the α Centauri binary system. Theoretical oscillation spectra are then calculated from stellar evolutionary models that include the effects of turbulence based on the LES simulations. By taking both non-seismic and seismic observational constraints into account we discuss the possibility to probe turbulence beyond standard 5mixing-length-theory in a star other than Sun.
Thermal convection in accretion disks
Authors: Klahr Hubert
Published: May 2007

For a long time it was believed that thermal convection could serve as the driving mechanism for turbulence and angular momentum transport in accretion disks. Even it is meanwhile accepted that convection had to leave that role to the magneto rotational instability, it is still an important effect arising in a realistic treatment of accretion disks, i.e. with proper thermodynamics and radiation transport. We review the history of thermal convection in astrophysical disks and show the relevant analytic and numerical work, including energy transport by convection and the effect of “negative” Reynolds stresses. We will also place the convective instability into the context of the magnetorotational instability and planet–disk interaction.