bluuebunny/crossref_metadata_2025 huggingface dataset:
The motion of solid particles suspended in viscoelastic liquids under torsional shear
Authors: Feng J. , Joseph D. D.
Published: April 2006

This paper presents an experimental study of the behaviour of single particles and suspensions in polymer solutions in a torsional flow. Four issues are investigated in detail: the radial migration of a shperical particle; the rotation and migration of a cylindrical particle; the particle-particle interaction and microstructures in a suspension of spheres; and the microstructures in a suspension of rods. Newtonian fluids are also tested under similar flow conditions for comparison. A spherical particle migrates outward at constant velocity unless the polymer solution is very dilute. A rod in a viscoelastic fluid has two modes of motion depending on its initial orientation, aspect ratio, the local shear rate and the magnitude of normal stresses in the fluid. In the first mode, the rod rotates along a Jeffery-like orbit around the local vorticity axis. It also migrates slowly inward. The second mode of motion has the rod aligned with the local stream at all times; the radial migration is outward. A hypothesis proposed by Highgate & Whorlow (1968) on the radial force on a particle in a cone-and-plate geometry is generalized to explain the variation of migration speed in torsional flows. Spheres form chains and aggregates when the suspension is sheared. The chains are along the flow direction and may connect to form circular rings; these rings migrate outward at a velocity much higher than that of a single sphere. Rods interact with one another and aggregate in much the same way, but to a lesser extent than spheres. It is argued that the particle interaction and aggregation are not direct results of the shear flow field. Two fundamental mechanisms discovered in sedimentation are applied to explain the formation of chains and aggregates. Finally, the competition between inertia and elasticity is discussed. A change of type is not observed in steady shear, but may happen in small-amplitude oscillatory shear.
Sound wave structures downstream of pseudo-steady weak and strong Mach reflections
Authors: Liu J. J.
Published: April 2006

Sound wave structures, downstream of moving incident shocks reflecting from straight compressive wedges, are analysed for both weak and strong Mach reflections (MR) using existing experiments. It is shown that the reflected waves can be well described by using the acoustic criterion or the weak oblique shock approximation, when the classical three-shock theory gives forward-facing reflected shock solutions. The predicted triple-point trajectory angles are found to be in close agreement with the experiments. The distinction between the applicabilities of the two methods is given by an analytically defined ‘smallness’ for the angle of reflecting wedges. The physics of the success of the two methods is discussed. It is concluded that forward-facing reflected shock solutions of pseudo-steady MR should be ruled out physically because sound waves cannot coalesce into Mach waves that propagate upstream of the triple point. In their place, MR-like phenomena occur with the reflected waves being normal Mach waves or finite compression waves for ‘small’ or ‘not-small’ reflecting wedge angles, respectively, and they are classified as the first- or second-king von Neumann reflections, respectively. Boundaries separating regimes between the first and second kinds of von Neumann reflections, and backward-facing MR are determined.
Expanding gas clouds of ellipsoidal shape: new exact solutions
Authors: Gaffet B.
Published: April 2006

We consider a model of a freely expanding gas cloud of tri-axial ellipsoidal shape, Gaussian density profile, proposed by Dyson (1968). The ellipsoids are deformable, but are further constrained here to have principal axes maintaining a fixed orientation in space: the study of the more general rotating flows is deferred to a future work. Our main result is that, when the fluid is a monatomic gas with adiabatic index γ = 5/3, the model is completely integrable by quadratures. Solutions starting from a state of rest are describable by elliptic functions; the generic solution however is a more general transcendent that cannot be reduced to elliptic type.

The complete integrability of Dyson's model may be ascribed to the fact that it possesses the Painlevé property (Ince 1956; Ablowitz & Segur 1977), meaning, essentially, that the solutions are meromorphic functions of the independent variable, admitting only pole singularities. However, the correct choice of independent variable here is not just the physical time t: rather, it is the thermasy (van Danzig 1939) u = ∫ Tdt, which is one of the potentials occurring in the Clebsch transformation.

Further investigation will be required to test Dyson's full ‘spinning gas cloud’ model for an eventual Painlevé property.
Nonlinear stability of continuously stratified quasi-geostrophic flow
Authors: Yongming Liu , Mu Mu , Shepherd Theodore G.
Published: April 2006

Nonlinear stability theorems analogous to Arnol'd's second stability theorem are established for continuously stratified quasi-geostrophic flow with general nonlinear boundary conditions in a vertically and horizontally confined domain. Both the standard quasi-geostrophic model and the modified quasi-geostrophic model (incorporating effects of hydrostatic compressibility) are treated. The results establish explicit upper bounds on the disturbance energy, the disturbance potential enstrophy, and the disturbance available potential energy on the horizontal boundaries, in terms of the initial disturbance fields. Nonlinear stability in the sense of Liapunov is also established.
Experiments on particle—turbulence interactions in the near–wall region of an open channel flow: implications for sediment transport
Authors: Ninto Y. , Garcia M. H.
Published: April 2006

A high-speed video system was used to study the interaction between sediment particles and turbulence in the wall region of an open channel flow with both smooth and transitionally rough beds. In smooth flows, particles immersed within the viscous sublayer were seen to accumulate along low-speed wall streaks; apparently due to the presence of quasi-streamwise vortices in the wall region. Larger particles did not tend to group along streaks, however their velocity was observed to respond to the streaky structure of the flow velocity in the wall region. In transitionally rough flows particle sorting was not observed. Coherent flow structures in the form of shear layers typically observed in the near-wall region interacted with sediment particles lying on the channel bottom, resulting in the particles being entrained into suspension. Although there has been some speculation that this process would not be effective in entraining particles totally immersed in the viscous sublayer, the results obtained demonstrate the opposite. The entrainment mechanism appears to be the same independent of the roughness condition of the bottom wall, smooth or transitionally rough. In the latter case, however, hiding effects tend to preclude the entrainment of particles with sizes finer than that of the roughness elements. The analysis of particle velocity during entrainment shows that the streamwise component tends to be much smaller than the local mean flow velocity, while the vertical component tends to be much larger than the local standard deviation of the vertical flow velocity fluctuations, which would indicate that such particles are responding to rather extreme flow ejection events.
Three-dimensional instability of axisymmetric buoyant convection in cylinders heated from below
Authors: Wanschura M. , Kuhlmann H. C. , Rath H. J.
Published: April 2006

The stability of steady axisymmetric convection in cylinders heated from below and insulated laterally is investigated numerically using a mixed finite-difference/Chebyshev collocation method to solve the base flow and the linear stability equations. Linear stability boundaries are given for radius to height ratios γ from 0.9 to 1.56 and for Prandtl numbers Pr = 0.02 and Pr = 1. Depending on γ and Pr, the azimuthal wavenumber of the critical mode may be m = 1, 2, 3, or 4. The dependence of the critical Rayleigh number on the aspect ratio and the instability mechanisms are explained by analysing the energy transfer to the critical modes for selected cases. In addition to these results the onset of buoyant convection in liquid bridges with stress-free conditions on the cylindrical surface is considered. For insulating thermal boundary conditions, the onset of convection is never axisymmetric and the critical azimuthal wavenumber increases monotonically with γ. The critical Rayleigh number is less then 1708 for most aspect ratios.
The instability and breakdown of tall columnar vortices in a quasi-geostrophic fluid
Authors: Dritschel David G. , JuáRez Manuel De La Torre
Published: April 2006

We examine the linear stability of elliptical columns of uniform potential vorticity subject to two-dimensional (horizontal) straining within a rapidly rotating, stratified (quasi-geostrophic) fluid. We find that horizontal straining can promote the exponential growth of three-dimensional disturbances when the vortex height-to-width aspect ratio exceeds, qualitatively, three times the ratio of the Coriolis parameter to the buoyancy frequency. This instability is not related to the usual baroclinic instability which operates on shallow vortex columns whose potential vorticity changes sign with height. The nonlinear development of these instabilities is investigated numerically using a high-resolution contour surgery algorithm. Simulations are conducted for both a Boussinesq (ocean-like) fluid and a compressible (atmospheric-like) fluid having exponentially decreasing density with height. The simulations reveal a generic nonlinear development that results in a semi-ellipsoidal baroclinic vortex dome at the lower surface and, in the case of a Boussinesq fluid, another such dome at the upper surface.

The related problem of two interacting vortex columns is also examined. A generic three-dimensional instability and nonlinear development occurs no matter how great the distance between the vortex columns, provided that they are sufficiently tall.

Our results may bear upon the observed structure of many atmospheric and oceanic vortices, whose height-to-width aspect ratios are consistent with our findings. Remarkably, even strongly ageostrophic vortices, such as tropical cyclones, fit the pattern. Our results furthermore re-open questions about the long-time nature of freely decaying quasi-geostrophic turbulence, for which recent simulations indicate a progressive two-dimensionalization by vortex alignment, while earlier simulations have indicated long-lived baroclinic vortices, not unlike what we find here.
Upper bounds for turbulent Couette flow incorporating the poloidal power constraint
Authors: Kerswell R. R. , Soward A. M.
Published: April 2006

The upper bound on momentum transport in the turbulent regime of plane Couette flow is considered. Busse (1970) obtained a bound from a variational formulation based on total energy conservation and the mean momentum equation. Two-dimensional asymptotic solutions of the resulting Euler-Lagrange equations for the system were obtained in the large-Reynolds-number limit. Here we make a toroidal poloidal decomposition of the flow and impose an additional power integral constraint, which cannot be satisfied by two-dimensional flows. Nevertheless, we show that the additional constraint can be met by only small modifications to Busse's solution, which leaves his momentum transport bound unaltered at lowest order. On the one hand, the result suggests that the addition of further integral constraints will not significantly improve bound estimates. On the other, our optimal solution, which possesses a weak spanwise roll in the outermost of Busse's nested boundary layers, appears to explain the three-dimensional structures observed in experiments. Only in the outermost boundary layer and in the main stream is the solution three-dimensional. Motion in the thinner layers remains two-dimensional characterized by streamwise rolls.
Bénard–Marangoni instability in rigid rectangular containers
Authors: Dauby P. C. , Lebon G.
Published: April 2006

Thermocapillary convection in three-dimensional rectangular finite containers with rigid lateral walls is studied. The upper surface of the fluid layer is assumed to be flat and non-deformable but is submitted to a temperature-dependent surface tension. The realistic ‘no-slip’ condition at the sidewalls makes the method of separation of variables inapplicable for the linear problem. A spectral Tau method is used to determine the critical Marangoni number and the convective pattern at the threshold as functions of the aspect ratios of the container. The influence on the critical parameters of a non-vanishing gravity and a non-zero Biot number at the upper surface is also examined. The nonlinear regime for pure Marangoni convection (Ra = 0) and for Pr = 104, Bi = 0 is studied by reducing the dynamics of the system to the dynamics of the most unstable modes of convection. Owing to the presence of rigid walls, it is shown that the convective pattern above the threshold may be quite different from that predicted by the linear approach. The theoretical predictions of the present study are in very good agreement with the experiments of Koschmieder & Prahl (1990) and agree also with most of Dijkstra's (1995a, b) numerical results. Important differences with the analysis of Rosenblat, Homsy & Davis (1982b) on slippery walls containers are emphasized.
Rapid-distortion turbulence models in the theory of surface-wave generation
Authors: Van Duin Cornelis A.
Published: April 2006

Turbulent air flow over a surface gravity wave of small amplitude is studied analytically on the basis of a family of rapid-distortion turbulence models. Results for the wave growth rate do not depend sensitively on the specific choice of these models. However, the agreement with results based on a so-called truncated mixing-length model (Belcher & Hunt 1993) is poor, despite physical similarity of the models. The present analysis also shows that the use of turbulence models based on rapid-distortion theory leads to significant underestimation of observed growth rates of high-frequency waves.
Active control in the turbulent wall layer of a minimal flow unit
Authors: Carlson Henry A. , Lumley John L.
Published: April 2006

Direct simulations of flow in a channel with complex, time-dependent wall geometries facilitate an investigation of smart skin control in a turbulent wall layer (with skin friction drag reduction as the goal). The test bed is a minimal flow unit, containing one pair of coherent structures in the near-wall region: a high- and a low-speed streak. The controlling device consists of an actuator, Gaussian in shape and approximately twelve wall units in height, that emerges from one of the channel walls. Raising the actuator underneath a low-speed streak effects an increase in drag, raising it underneath a high-speed streak effects a reduction – indicating a mechanism for control. In the high-speed region, fast-moving fluid is lifted by the actuator away from the wall, allowing the adjacent low-speed region to expand and thereby lowering the average wall shear stress. Conversely, raising an actuator underneath a low-speed streak allows the adjacent high-speed region to expand, which increases skin drag.
The Political Makings of the 2001 Lootings in Argentina
Authors: AUYERO JAVIER
Published: April 2006

Based on archival research and on multi-sited fieldwork, this article offers the first available description of the food lootings that took place in Argentina in December 2001. The paper joins the current relational turn in the study of collective violence. It examines the existing continuities between everyday life, routine politics and extraordinary massive actions, and scrutinises the grey zone where the deeds and networks of looters, political entrepreneurs and law enforcement officials meet and mesh. The article reconstructs the looting dynamics at one specific site and highlights the existence of three mechanisms during the episodes: 1. the creation of opportunities by party brokers and police agents, 2. the validation of looting by state elites, and 3. the signalling spiral carried out by party brokers.
Getting over the Andes: The Geo-Eco-Politics of Indigenous Movements in Peru's Twenty-First Century Inca Empire
Authors: GREENE SHANE
Published: April 2006

This article examines how President Alejandro Toledo's self-professed Andean identity and efforts to establish a state-led indigenous rights framework conflicted with a growing eco-ethno alliance of Andean and Amazonian representatives in Peru. Existing scholarly accounts declare the indigenous movement to be unimportant or, indeed, entirely absent in Peru. Yet, they do so by emphasising the centrality of the historical dynamic between the Andean region, where until recently local peoples have desisted from making explicit indigenous claims, and the urbanised coastal region, where the elite's power is most clearly concentrated. This obscures the Amazon as a site of historical events and eco-ethno-politics of national and global scope. The recent emergence of a debate on indigenous issues shows that the Amazonians' longer engagement in the global sphere of indigenous and environmental politics now places them in the position of exemplifying indigeneity for the Andeans and Peruvians at large. This shift challenges in fundamental ways the historical image of Peru the nation as inextricably implicated in the post-colonial fantasies of what I term the ‘Inca slot’.
Paramilitarism and Colombia's Low-Intensity Democracy
Authors: AVILÉS WILLIAM
Published: April 2006

In the late 1980s and early 1990s political liberalisation, including the reduction of the military's institutional prerogatives, occurred in Colombia despite the increasing strength of an internal insurgency. Why would Colombia's national political elite weaken the institutional role of the armed forces in the context of an escalating internal war? What was the role of paramilitary groups, which were responsible for the vast majority of massacres and political violence against suspected unarmed civilians, during the 1990s? This paper argues that the elite civilian politicians who dominated the Colombian state promoted formal institutional changes, but tolerated paramilitary repression in order to counteract a strengthening guerrilla insurgency. These civilian leaders represented a modernising elite focused upon co-opting political opposition and establishing neoliberal economic reforms, thus constructing a Low-Intensity Democracy.
42-jähriger Mann mit schmerzloser Schwellung am Kleinfinger
Authors: von Känel  , Schweizer  , Jundt  , Meuli-Simmen
Published: April 2006

Ein 42-jähriger Mann wurde uns wegen einer seit fünf Monaten bestehenden, an Grösse zunehmenden, schmerzlosen Schwellung im Bereich von Grundphalanx und Mittelhandknochen des linken Ringfingers zugewiesen, welche sich radiologisch als subkutane Verkalkung darstellte. Die differentialdiagnostischen Überlegungen bei verkalkten Tumoren im Bereich der Finger werden im Hinblick auf das korrekte weitere Vorgehen diskutiert. Die histologische Untersuchung nach vollständiger Exzision der Läsion ergab eine bizarre periostale osteochromatöse Proliferation (= Nora Läsion). Diese seltene Läsion gilt es von einem periostalen Osteosarkom abzugrenzen.
Force-dependent chemical kinetics of disulfide bond reduction observed with single-molecule techniques
Authors: Wiita Arun P. , Ainavarapu Sri Rama Koti , Huang Hector H. , Fernandez Julio M.
Published: April 2006

The mechanism by which mechanical force regulates the kinetics of a chemical reaction is unknown. Here, we use single-molecule force–clamp spectroscopy and protein engineering to study the effect of force on the kinetics of thiol/disulfide exchange. Reduction of disulfide bonds through the thiol/disulfide exchange chemical reaction is crucial in regulating protein function and is known to occur in mechanically stressed proteins. We apply a constant stretching force to single engineered disulfide bonds and measure their rate of reduction by DTT. Although the reduction rate is linearly dependent on the concentration of DTT, it is exponentially dependent on the applied force, increasing 10-fold over a 300-pN range. This result predicts that the disulfide bond lengthens by 0.34 Å at the transition state of the thiol/disulfide exchange reaction. Our work at the single bond level directly demonstrates that thiol/disulfide exchange in proteins is a force-dependent chemical reaction. Our findings suggest that mechanical force plays a role in disulfide reduction
in vivo
, a property that has never been explored by traditional biochemistry. Furthermore, our work also indicates that the kinetics of any chemical reaction that results in bond lengthening will be force-dependent.
A client‐generated psychometric instrument: The development of ‘PSYCHLOPS’
Authors: Ashworth Mark , Shepherd Melanie , Christey Jeremy , Matthews Veronica , Wright Kevin , Parmentier Henk , Robinson Susan , Godfrey Emma
Published: April 2006

PSYCHLOPS (Psychological Outcome Profiles) is a recently developed, client‐generated, psychometric instrument that can be used as an outcome measure. Based on a similar instrument developed primarily for use in physical illnesses (MYMOP — ‘Measure Your Medical Outcome Profile’), it seeks the client's perspective on their psychological distress. It asks them to describe and then score the problem that troubles them the most at the start of counselling. We describe the development of PSYCHLOPS, including the involvement of the Plain English Campaign and two national mental health organisations: the mental health charity and support group, Depression Alliance (DA) and Primary Care Mental Health Education (PRIMHE). We review the literature and suggest that PSYCHLOPS, by focusing on the problems of greatest priority to the client, might prove a sensitive measure of improvement after counselling.
Writing therapy in brief workplace counselling: Collaborative writing as inquiry
Authors: Wright Jeannie K.
Published: April 2006

The purpose of this collaborative research was to reflect on one client's experience of using writing therapy during brief workplace counselling. The client/co‐researcher used expressive and creative writing between counselling sessions, the benefits of which are reported. A brief review of the literature on writing therapy is provided. The focus of the study is on investigating the process of writing therapy from the client's point of view. The epistemological assumptions and research methods are influenced by narrative inquiry. Feminist values inform both the therapeutic practice and research.
Therapists’ experiences of relational depth: A qualitative interview study
Authors: Cooper Mick
Published: April 2006

The aim of this study was to explore therapists’ experiences of meeting their clients at a level of ‘relational depth’. This was defined as a feeling of profound contact and engagement with another, in which the therapists experienced high levels of empathy, acceptance and transparency towards their clients, and experienced their clients as acknowledging their empathy and acceptance in a genuine way. Participants were primarily experienced person‐centred therapists, five of whom were female and three of whom were male. Data was gathered through the use of qualitative, unstructured interviews within the broader framework of a person‐centred and phenomenological methodology. All interviewees described experiencing moments of relational depth with their clients, and substantial commonalities emerged in their descriptions. These included heightened feelings of empathy, acceptance and receptivity towards their clients; powerful feelings of immersion in the therapeutic work; increased perceptual clarity; and greater levels of awareness, aliveness and satisfaction. At these times, the therapists also experienced their clients as highly transparent; articulating core concerns and issues; and reciprocating the therapist's acknowledgement of them in a flowing, bi‐directional encounter. These findings are discussed in relation to recent research on ‘presence’ and ‘flow’ and it is proposed that relational depth can be conceptualised as a form of ‘co‐presence’ or a co‐experiencing of the person‐centred ‘core conditions’. Limitations of the study and areas for further research are discussed.
On Cartan matrices and lower defect groups for covering groups of symmetric groups
Authors: Bessenrodt Christine , Olsson Jørn
Published: April 2006

We determine the elementary divisors of the Cartan matrices of spin

p
p

-blocks of the covering groups of the symmetric groups when

p
p

is an odd prime. As a consequence, we also compute the determinants of these Cartan matrices, and in particular we confirm a conjecture by Brundan and Kleshchev that these determinants depend only on the weight but not on the sign of the block.
Unital bimodules over the simple Jordan superalgebra 𝐷(𝑡)
Authors: Martínez Consuelo , Zelmanov Efim
Published: April 2006

We classify indecomposable finite dimensional bimodules over Jordan superalgebras

D
(
t
)

D(t)

,

t
≠
−
1
,
0
,
1

t \neq -1,0,1

.
On decompositions in homotopy theory
Authors: Gray Brayton
Published: April 2006

We first describe Krull-Schmidt theorems decomposing

H
H

spaces and simply-connected co-

H
H

spaces into atomic factors in the category of pointed nilpotent

p
p

-complete spaces of finite type. We use this to construct a 1-1 correspondence between homotopy types of atomic

H
H

spaces and homotopy types of atomic co-

H
H

spaces, and construct a split fibration which connects them and illuminates the decomposition. Various properties of these constructions are analyzed.
Length, multiplicity, and multiplier ideals
Authors: de Fernex Tommaso
Published: April 2006

Let

(
R
,

m

)

(R,\mathfrak {m})

be an

n
n

-dimensional regular local ring, essentially of finite type over a field of characteristic zero. Given an

m

\mathfrak {m}

-primary ideal

a

\mathfrak {a}

of

R
R

, the relationship between the singularities of the scheme defined by

a

\mathfrak {a}

and those defined by the multiplier ideals

J

(

a

c

)

\mathcal {J}(\mathfrak {a}^c)

, with

c
c

varying in

Q

+

\mathbb {Q}_+

, are quantified in this paper by showing that the Samuel multiplicity of

a

\mathfrak {a}

satisfies

e
(

a

)
≥
(
n
+
k

)
n

/

c
n

e(\mathfrak {a}) \ge (n+k)^n/c^n

whenever

J

(

a

c

)
⊆

m

k
+
1

\mathcal {J}(\mathfrak {a}^c) \subseteq \mathfrak {m}^{k+1}

. This formula generalizes an inequality on log canonical thresholds previously obtained by Ein, Mustaţǎ and the author of this paper. A refined inequality is also shown to hold for small dimensions, and similar results valid for a generalization of test ideals in positive characteristics are presented.
Nonnegative solvability of linear equations in certain ordered rings
Authors: Scowcroft Philip
Published: April 2006

In the integers and in certain densely ordered rings that are not fields, projections of the solution set of finitely many homogeneous weak linear inequalities may be defined by finitely many congruence inequalities, where a congruence inequality combines a weak inequality with a system of congruences. These results extend well-known facts about systems of weak linear inequalities over ordered fields and imply corresponding analogues of Farkas’ Lemma on nonnegative solvability of systems of linear equations.
On the Eshelby-Kostrov property for the wave equation in the plane
Authors: Herrero M. , Oleaga G. , Velázquez J.
Published: April 2006

This work deals with the linear wave equation considered in the whole plane

R

2

\mathbb {R}^{2}

except for a rectilinear moving slit, represented by a curve

Γ

(
t
)

=

{

(

x

1

,
0
)

:
−
∞
>

x

1

>
λ

(
t
)

}

\Gamma \left ( t\right ) =\left \{ \left ( x_{1},0\right ) :-\infty >x_{1}>\lambda \left ( t\right ) \right \}

with

t
≥
0.

t\geq 0.

Along

Γ

(
t
)

,

\Gamma \left ( t\right ) ,

either homogeneous Dirichlet or Neumann boundary conditions are imposed. We discuss existence and uniqueness for these problems, and derive explicit representation formulae for solutions. The latter have a simple geometrical interpretation, and in particular allow us to derive precise asymptotic expansions for solutions near the tip of the curve. In the Neumann case, we thus recover a classical result in fracture dynamics, namely the form of the stress intensity factor in crack propagation under antiplane shear conditions.
Kirwan-Novikov inequalities on a manifold with boundary
Authors: Braverman Maxim , Silantyev Valentin
Published: April 2006

We extend the Novikov Morse-type inequalities for closed 1-forms in 2 directions. First, we consider manifolds with boundary. Second, we allow a very degenerate structure of the critical set of the form, assuming only that the form is non-degenerated in the sense of Kirwan. In particular, we obtain a generalization of a result of Floer about the usual Morse inequalities on a manifold with boundary. We also obtain an equivariant version of our inequalities. Our proof is based on an application of the Witten deformation technique. The main novelty here is that we consider the neighborhood of the critical set as a manifold with a cylindrical end. This leads to a considerable simplification of the local analysis. In particular, we obtain a new analytic proof of the Morse-Bott inequalities on a closed manifold.
Lower and upper Loeb-integrals
Authors: Landers D. , Rogge L.
Published: April 2006

We introduce the concepts of lower and upper Loeb-integrals for an internal integration structure. These are concepts which are similarly useful for Loebs internal integration theory as the concepts of inner and outer Loeb-measures for Loebs measure theory.
Geometric structures as deformed infinitesimal symmetries
Authors: Blaom Anthony
Published: April 2006

A general model for geometric structures on differentiable manifolds is obtained by deforming infinitesimal symmetries. Specifically, this model consists of a Lie algebroid, equipped with an affine connection compatible with the Lie algebroid structure. The curvature of this connection vanishes precisely when the structure is locally symmetric. This model generalizes Cartan geometries, a substantial class, to the intransitive case. Simple examples are surveyed and corresponding local obstructions to symmetry are identified. These examples include foliations, Riemannian structures, infinitesimalGG-structures, symplectic and Poisson structures.
A general theory of almost convex functions
Authors: Dilworth S. , Howard Ralph , Roberts James
Published: April 2006

Let
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Delta Subscript m Baseline equals left-brace left-parenthesis t 0 comma ellipsis comma t Subscript m Baseline right-parenthesis element-of bold upper R Superscript m plus 1 Baseline colon t Subscript i Baseline greater-than-or-equal-to 0 comma sigma-summation Underscript i equals 0 Overscript m Endscripts t Subscript i Baseline equals 1 right-brace">

Δ
m

=
{
(

t
0

,
…
,

t
m

)
∈

R

m
+
1

:

t
i

≥
0
,

∑

i
=
0

m

t
i

=
1
}

\Delta _m=\{(t_0,\dots , t_m)\in \mathbf {R}^{m+1}: t_i\ge 0, \sum _{i=0}^mt_i=1\}

be the standard

m
m

-dimensional simplex and let

∅
≠
S
⊂

⋃

m
=
1

∞

Δ
m

\varnothing \ne S\subset \bigcup _{m=1}^\infty \Delta _m

. Then a function

h
:
C
→

R

h\colon C\to \mathbf {R}

with domain a convex set in a real vector space is

S
S

-almost convex iff for all

(

t
0

,
…
,

t
m

)
∈
S

(t_0,\dots , t_m)\in S

and

x
0

,
…
,

x
m

∈
C

x_0,\dots , x_m\in C

the inequality
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="h left-parenthesis t 0 x 0 plus midline-horizontal-ellipsis plus t Subscript m Baseline x Subscript m Baseline right-parenthesis less-than-or-equal-to 1 plus t 0 h left-parenthesis x 0 right-parenthesis plus midline-horizontal-ellipsis plus t Subscript m Baseline h left-parenthesis x Subscript m Baseline right-parenthesis">

h
(

t
0

x
0

+
⋯
+

t
m

x
m

)
≤
1
+

t
0

h
(

x
0

)
+
⋯
+

t
m

h
(

x
m

)

h(t_0x_0+\dots +t_mx_m)\le 1+ t_0h(x_0)+\cdots +t_mh(x_m)

\]
holds. A detailed study of the properties of

S
S

-almost convex functions is made. If

S
S

contains at least one point that is not a vertex, then an extremal

S
S

-almost convex function

E
S

:

Δ
n

→

R

E_S\colon \Delta _n\to \mathbf {R}

is constructed with the properties that it vanishes on the vertices of

Δ
n

\Delta _n

and if

h
:

Δ
n

→

R

h\colon \Delta _n\to \mathbf {R}

is any bounded

S
S

-almost convex function with

h
(

e
k

)
≤
0

h(e_k)\le 0

on the vertices of

Δ
n

\Delta _n

, then

h
(
x
)
≤

E
S

(
x
)

h(x)\le E_S(x)

for all

x
∈

Δ
n

x\in \Delta _n

. In the special case

S
=
{
(
1

/

(
m
+
1
)
,
…
,
1

/

(
m
+
1
)
)
}

S=\{(1/(m+1),\dotsc , 1/(m+1))\}

, the barycenter of

Δ
m

\Delta _m

, very explicit formulas are given for

E
S

E_S

and

κ
S

(
n
)
=

sup

x
∈

Δ
n

E
S

(
x
)

\kappa _S(n)=\sup _{x\in \Delta _n}E_S(x)

. These are of interest, as

E
S

E_S

and

κ
S

(
n
)

\kappa _S(n)

are extremal in various geometric and analytic inequalities and theorems.
Explicit bounds for the finite jet determination problem
Authors: Lamel Bernhard
Published: April 2006

We introduce biholomorphic invariants for (germs of) rigid holomorphically nondegenerate real hypersurfaces in complex space and show how they can be used to compute explicit bounds on the order of jets for which biholomorphisms of the hypersurface are determined uniquely by their jets. The main result which allows us to derive these bounds is a theorem which shows that solutions of certain singular analytic equations are uniquely determined by their

1
1

-jet.
Amino Acids Regulate Retrieval of the Yeast General Amino Acid Permease from the Vacuolar Targeting Pathway
Authors: Rubio-Texeira Marta , Kaiser Chris A.
Published: April 2006

Intracellular sorting of the general amino acid permease (Gap1p) in Saccharomyces cerevisiae depends on availability of amino acids such that at low amino acid concentrations Gap1p is sorted to the plasma membrane, whereas at high concentrations Gap1p is sorted to the vacuole. In a genome-wide screen for mutations that affect Gap1p sorting we identified deletions in a subset of components of the ESCRT (endosomal sorting complex required for transport) complex, which is required for formation of the multivesicular endosome (MVE). Gap1p-GFP is delivered to the vacuolar interior by the MVE pathway in wild-type cells, but when formation of the MVE is blocked by mutation, Gap1p-GFP efficiently cycles from this compartment to the plasma membrane, resulting in unusually high permease activity at the cell surface. Importantly, cycling of Gap1p-GFP to the plasma membrane is blocked by high amino acid concentrations, defining recycling from the endosome as a major step in Gap1p trafficking under physiological control. Mutations in LST4 and LST7 genes, previously identified for their role in Gap1p sorting, similarly block MVE to plasma membrane trafficking of Gap1p. However, mutations in other recycling complexes such as the retromer had no significant effect on the intracellular sorting of Gap1p, suggesting that Gap1p follows a genetically distinct pathway for recycling. We previously found that Gap1p sorting from the Golgi to the endosome requires ubiquitination of Gap1p by an Rsp5p ubiquitin ligase complex, but amino acid abundance does not appear to significantly alter the accumulation of polyubiquitinated Gap1p. Thus the role of ubiquitination appears to be a signal for delivery of Gap1p to the MVE, whereas amino acid abundance appears to control the cycling of Gap1p from the MVE to the plasma membrane.
Multiple Sequence Elements Facilitate Chp Rho GTPase Subcellular Location, Membrane Association, and Transforming Activity
Authors: Chenette Emily J. , Mitin Natalia Y. , Der Channing J.
Published: April 2006

Cdc42 homologous protein (Chp) is a member of the Rho family of small GTPases and shares significant sequence and functional similarity with Cdc42. However, unlike classical Rho GTPases, we recently found that Chp depends on palmitoylation, rather than prenylation, for association with cellular membranes. Because palmitoylation alone is typically not sufficient to promote membrane association, we evaluated the possibility that other carboxy-terminal residues facilitate Chp subcellular association with membranes. We found that Chp membrane association and transforming activity was dependent on the integrity of a stretch of basic amino acids in the carboxy terminus of Chp and that the basic amino acids were not simply part of a palmitoyl acyltransferase recognition motif. We also determined that the 11 carboxy-terminal residues alone were sufficient to promote Chp plasma and endomembrane association. Interestingly, stimulation with tumor necrosis factor-α activated only endomembrane-associated Chp. Finally, we found that Chp membrane association was not disrupted by Rho guanine nucleotide dissociation inhibitory proteins, which are negative regulators of Cdc42 membrane association and biological activity. In summary, the unique carboxy-terminal sequence elements that promote Chp subcellular location and function expand the complexity of mechanisms by which the cellular functions of Rho GTPases are regulated.
The Phosphoinositide Kinase PIKfyve/Fab1p Regulates Terminal Lysosome Maturation inCaenorhabditis elegans
Authors: Nicot Anne-Sophie , Fares Hanna , Payrastre Bernard , Chisholm Andrew D. , Labouesse Michel , Laporte Jocelyn
Published: April 2006

Membrane dynamics is necessary for cell homeostasis and signal transduction and is in part regulated by phosphoinositides. Pikfyve/Fab1p is a phosphoinositide kinase that phosphorylates phosphatidylinositol 3-monophosphate into phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P2] and is implicated in membrane homeostasis in yeast and in mammalian cells. These two phosphoinositides are substrates of myotubularin phosphatases found mutated in neuromuscular diseases. We studied the roles of phosphatidylinositol phosphate kinase 3 (PPK-3), the orthologue of PIKfyve/Fab1p, in a multicellular organism, Caenorhabditis elegans. Complete loss of ppk-3 function induces developmental defects characterized by embryonic lethality, whereas partial loss of function leads to growth retardation. At the cellular level, ppk-3 mutants display a striking enlargement of vacuoles positive for lysosome-associated membrane protein 1 in different tissues. In the intestine, RAB-7–positive late endosomes are also enlarged. Membranes of the enlarged lysosomes originate at least in part from smaller lysosomes, and functional and genetic analyses show that the terminal maturation of lysosomes is defective. Protein degradation is not affected in the hypomorphic ppk-3 mutant and is thus uncoupled from membrane retrieval. We measured the level of PtdIns(3,5)P2and showed that its production is impaired in this mutant. This work strongly suggests that the main function of PPK-3 is to mediate membrane retrieval from matured lysosomes through regulation of PtdIns(3,5)P2.
A Study of the psychological effects of facial deformity in children
Authors: LANSDOWN RICHARD , POLAK LETTEKE
Published: April 2006

SUMMARY
Anecdotal reports of the psychological effects of facial deformity suggest that the area around the mouth is of crucial importance. In the first of two studies, children‐ in London and Amsterdam ranked drawings of facially deformed children; their ordering was consistent, with a hare lip or protruding teeth being the most commonly rejected.

A second study followed up 24 children aged about 8 years who had had a hare lip repair. The results did not confirm the hypothesis that such children differ from their non‐handicapped peers in overt behaviour in school.
Follow‐up at II years of children who had marked speech defects at 7 years
Authors: SHERIDAN MARY D. , PECKHAM CATHERINE
Published: April 2006

SUMMARY
The results of a follow‐up study at 11 years of 215 children in the National Child Development Study who were reported to show marked speech defects at 7 years are presented. Information regarding social welfare, health and scholastic attainments was available for 190 children (88%). Over a third of these had been formally ‘ascertained’ for special educational treatment. Of the 124 children remaining in ordinary schools, 56% still had residual speech problems while 44% were reported to have acquired satisfactory speech. The health and scholastic attainments of these two groups are described and discussed in relation to each other and to controls. A note regarding significant items in the original reports of 25 ‘missing’ children at 7 years is provided, indicating that the large proportion had serious additional handicaps at 7 years.

The importance of effective identification, full paediatric and educational assessment and the provision of appropriate help at or preferably before school entry is stressed.
The education of physically handicapped children in normal schools
Authors: BARRY CIARAN , GARVEY CRIONA , BYRNE MARY M.
Published: April 2006

SUMMARY
This paper is based on our experience in the Central Remedial Clinic over a number of years that physically handicapped children do not in general do well in ordinary schools. An attempt is made to delineate some of the problems that may confront a handicapped child of generally average intelligence who attends a normal school. These problems are associated with the following conditions: specific learning difficulties, emotional problems, poor school attendance, large classes, limitations in ordinary teacher training and lack of remedial teachers and other special staff. The need for early and continued psychological and educational assessments is emphasized, and it is suggested that most young physically handicapped children of average intelligence would benefit from starting in a special assessment unit, to ensure as far as possible, correct school placement. This view is not currently held by a number of educational authorities who generally advise that physically handicapped children should go to ordinary schools if possible. We feel that this advice is not always in the best interests of the child. There is need for continuing friendly and informal communications between parents and members of the special school team.
Profile: Toy libraries, school, hospital and home
Authors: TURNER PETER
Published: April 2006

SUMMARY
Toy libraries are now a well‐established component of the services available to the parents of handicapped children. Difficulties of varying kinds have inevitably arisen in the 5 years' history of the toy library movement, some of which could be resolved by linking developments of new libraries with existing institutions. The advantages of a toy library/institution link accrue to both elements of such a union and it is the purpose of this article to argue the case for an increase in the number of such developments.
Developmental training by parents of the very young child with potential handicap
Authors: COWAN MARGARET , BRENTON ANN
Published: April 2006

SUMMARY
Fifteen children aged 9 to 15 months, who were on the observation register of a city, and considered to be showing signs of delayed development, were studied over a 3‐month period.

Following assessment, the parents were shown ways in which they could train their children appropriate to their developmental levels, in separate fields of locomotion, social development, language, and hand‐eye coordination. Eight out of 13 children with delay showed significant improvement in general quotients of development over the 3 months. This occurred in 5 out of 7 children with no signs of neurological abnormality at the time of the study, and in 3 out of 6 children with signs of neurological disorder. Two children without delay showed no significant improvement.

Parents' reactions are discussed, and a description is given of the way in which this project was designed, suggesting implications for future Community Health services.
The importance of spontaneous play in the fundamental learning of handicapped children*
Authors: SHERIDAN MARY D.
Published: April 2006

SUMMARY
The main types, functions and developmental stages in the spontaneous play of normal infants and young children are outlined. Correspondences and differences in the play of handicapped children are discussed, with special reference to the importance of suitable playthings in the early development of general understanding, psychomotor functioning, manipulative ability, codes of communication and social adjustment. The need for improved ‘free‐field’ observational research using audiovisual recording techniques is stressed.
The role of boarding special schools in the treatment of children with recurrent disabling disorders
Authors: RACKHAM KATE
Published: April 2006

SUMMARY
This article examines three disorders, asthma, epilepsy and diabetes, suggesting that they have certain common features, being constitutional in origin, having periods of exacerbation with overt physical symptoms, requiring maintenance drug treatment and being potentially life‐threatening. Their effects upon personality, in particular in relation to social and educational failure, are outlined and the role of boarding school in the treatment of children so affected is described, together with criteria for selection for such treatment. The tendency towards entrenched attitudes in regard to boarding school is deprecated, preventing its consideration as a positive form of treatment for a small group of vulnerable children.
A study of the gross motor skills of cerebral palsied children in an adventure playground for handicapped children
Authors: LEVITT SOPHIE
Published: April 2006

SUMMARY
The research study involved a comparison of the range of physical abilities elicited by clinical assessment, with motor behaviour in the ploys ground.
A single nurse‐teacher‐therapist?
Authors: HOLT K. S.
Published: April 2006

SUMMARY
The training and work of the conductors at the Institute for the Conductive Education of the Motor Disabled and Conductors College, Budapest, Hungary, are described. Speculations about the advantages and disadvantages of single nurse‐teacher‐therapist for young handicapped children are discussed.
The attendance allowance
Authors: GREAVES MARY
Published: April 2006

SUMMARY
The National Insurance (old persons'and widows' pensions and attendance allowance) Act 1970 provides for an attendance allowance to be paid to disabled persons who require a lot of attention or supervision both at night and by day. With the passing of the National Insurance Act 1972 this became known as the higher rate and a new lower rate was introduced in 1973 for those who require a lot of attention or supervision either by day or at night. The current rates of attendance allowance are at the higher rate £8.00 a week and at the lower rate £5·35 a week. To qualify for the attendance allowance the conditions must have been satisfied for at least 6 months. The allowance can be paid from the age of 2 years, which means that the conditions must have been satisfied from the age of 18 months; one of the conditions for children is that they need substantially more attention or supervision than a non‐disabled child of the same age. Whether a person satisfies the medical conditions and if so for how long they are likely to remain satisfied is decided by the Attendance Allowance Board.
The incidence of visual handicap in Swedish children
Authors: LINDSTEDT EVA
Published: April 2006

SUMMARY
A sample of 1271 visually handicapped children has been analysed with regard to the degree and cause of visual impairment.
Incidence of visual defects in Yugoslavia
Authors: KALOGJERA TEODORA
Published: April 2006

SUMMARY
1645 children of 1–7 years of age and 103 4‐year‐old children of an unselected population were examined. Vision screening was performed as single E optotype. Schiascopy and fixation with visuscope were also performed. Results are presented in six tables.