bluuebunny/crossref_metadata_2025 huggingface dataset:
The popular uprising in Burkina Faso and the Transition
Authors: Chouli Lila
Published: April 2015

At the end of October 2014, Africa was again the scene of a popular uprising: in two days the people of Burkina Faso, in mass demonstrations, emptied the presidential palace of its occupant, exceeding even the slogans launched by political opposition and civil society organisations. On 31 October President Blaise Compaoré, after 27 years in power, was forced to resign. In this briefing, after a very brief overview of the dynamics of the struggles in Burkina Faso, Lila Chouli presents in broad outline the nature of the post-October transition, its relationship to the uprising and some of the principal contradictions and tensions contained in these developments.
1
Effects of liquid konjac on parameters related to obesity in diet-induced obese mice
Authors: Aoe Seiichiro , Kudo Haruka , Sakurai Seiya
Published: April 2015

Konjac-mannan has been suggested to exert a protective effect against visceral obesity. However, there is little knowledge about the effects of liquid konjac (LK) that is partially alkali gelled. The purpose of the present work was to evaluate the potential beneficial effects of a LK powder on obesity in mice. Male C57BL/6J mice were fed a high-fat diet supplemented with either 2.5 or 5% LK powder for 80 days. Growth parameters, abdominal fat content, serum biochemical markers, and hepatic lipid accumulations were measured. Dietary supplementation with LK resulted in decreased body weight gain and abdominal fat accumulation. Dose-dependent decreases were observed in accumulation of hepatic lipids and serum total cholesterol, leptin, insulin concentrations. The study findings indicated that LK had preventing effect against obesity, including the reduction of abdominal and hepatic lipid accumulation and serum parameters related to obesity.
Collaborative Treatment Planning Using the Sex Offender Treatment Intervention and Progress Scale (SOTIPS): Concordance of Therapist Evaluation and Client Self-Evaluation
Authors: Lasher Michael P. , McGrath Robert J. , Wilson Doug , Cumming Georgia F.
Published: April 2015

Contemporary views on sex offender treatment planning suggest that therapist and client collaboration may enhance treatment outcomes, but little research has examined this topic. The use of dynamic risk assessment instruments may provide insight into what criminogenic needs should be focused on for clients in sex offender treatment. Here, we compared therapist and client ( N = 80) mid-treatment assessment scores on the Sex Offender Treatment Intervention and Progress Scale (SOTIPS) in a prison-based treatment program for adult male sex offenders. The SOTIPS is 16-item dynamic assessment measure of treatment needs and progress that was designed to be scored at intake and thereafter as often as every six months on a four-point scale. Data were collected following the completion of SOTIPS as a group treatment exercise. Although there were significant overall differences in SOTIPS scores between therapists and clients ( t(79) = 6.50, p < .001; d = 1.03), SOTIPS scores related to criminality, social stability and supports, and sexual deviance showed substantial (ICC = 0.75, p < .001), moderate (ICC = 0.59, p < .001), and fair (ICC = 0.23, p < .05) correlations, respectfully. Using partial correlations, controlling for static risk showed no impact on these relationships. Findings are discussed in light of the experiences of therapists. This study suggests that the SOTIPS provides a useful framework for therapists to engage clients in a collaborative process of indentifying clients’ strengths, potential treatment needs, and treatment progress.
The Relationship between Mental Disorder and Recidivism in Sexual Offenders
Authors: Kingston Drew A. , Olver Mark E. , Harris Melissa , Wong Stephen C. P. , Bradford John M.
Published: April 2015

The importance of mental illness as a risk factor for violence has been debated with significant implications for mental health policy and clinical practice. In offender samples, mental health diagnoses tend to be unrelated to recidivism, although this effect has been questioned recently in sexual offenders. In the present, prospective investigation, the relevance of several mental health diagnoses and relevant co-morbidity is examined as predictors of various types of recidivism in two distinct samples of sexual offenders who were followed up to 27 years in the community. Results indicated that mental health diagnoses were not predictive of recidivism on their own or in multivariate categories, although comorbid substance-use disorders and some personality disorders showed some predictive validity. Results are discussed in the context of a social learning model of crime and in terms of the treatment of sexual offenders.
Treating Comorbid Substance Use and Traumatic Stress among Male Prisoners: A Pilot Study of the Acceptability, Feasibility, and Preliminary Efficacy of Seeking Safety
Authors: Barrett Emma Louise , Indig Devon , Sunjic Sandra , Sannibale Claudia , Sindicich Natasha , Rosenfeld Julia , Najavits Lisa M. , Mills Katherine
Published: April 2015

Co-occurring substance use disorder and posttraumatic stress disorder is prevalent among prisoners, however there are few evidence-based treatment options available for this population. This pilot study investigated the acceptability, feasibility and preliminary efficacy of implementing partial-dose (eight-session) Seeking Safety among 30 Australian male prisoners. Findings demonstrate that Seeking Safety is desirable, acceptable, and feasible among male prisoners with a history of substance use and trauma. In addition, the study indicated promising results for substance use and mental health outcomes, which is particularly notable given the overall severity of the sample. The study also had significant Aboriginal and/or Torres Strait Islander representation. A full scale trial of this intervention is required to further evaluate efficacy and inform practice to improve the mental health of this vulnerable population.
Positional demands of professional rugby
Authors: Lindsay Angus , Draper Nick , Lewis John , Gieseg Steven P. , Gill Nicholas
Published: April 2015

Rugby union is a physically intense intermittent sport coupled with high force collisions. Each position within a team has specific requirements which are typically based on speed, size and skill. The aim of this study was to investigate the contemporary demands of each position and whether they can explain changes in psychophysiological stress. Urine and saliva samples were collected before and after five selected Super 15 rugby games from 37 players. Total neopterin (NP), cortisol and immunoglobulin A were analysed by SCX‐high performance liquid chromatography and enzyme linked immunosorbent assay. Global positioning system software provided distance data, while live video analysis provided impact data. All contemporary demands were analysed as events per minute of game time. Forwards were involved in more total impacts, tackles and rucks compared to backs (p < 0.001), while backs were involved in more ball carries and covered more total distance and distance at high speed per minute of game time (p < 0.01). Loose forwards, inside and outside backs covered significantly more distance at high speed (p < 0.01), while there was a negligible difference with number of impacts between the forward positions. There was also minimal difference between positions in the percentage change in NP, cortisol and sIgA. The results indicate distance covered and number of impacts per minute of game time is position‐dependent whereas changes in psychophysiological stress are independent. This information can be used to adapt training and recovery interventions to better prepare each position based on the physical requirements of the game.
Rapid Communication: Pianists exhibit enhanced memory for vocal melodies but not piano melodies
Authors: Weiss Michael W. , Vanzella Patrícia , Schellenberg E. Glenn , Trehub Sandra E.
Published: April 2015

Nonmusicians remember vocal melodies (i.e., sung to la la) better than instrumental melodies. If greater exposure to the voice contributes to those effects, then long-term experience with instrumental timbres should elicit instrument-specific advantages. Here we evaluate this hypothesis by comparing pianists with other musicians and nonmusicians. We also evaluate the possibility that absolute pitch (AP), which involves exceptional memory for isolated pitches, influences melodic memory. Participants heard 24 melodies played in four timbres (voice, piano, banjo, marimba) and were subsequently required to distinguish the melodies heard previously from 24 novel melodies presented in the same timbres. Musicians performed better than nonmusicians, but both groups showed a comparable memory advantage for vocal melodies. Moreover, pianists performed no better on melodies played on piano than on other instruments, and AP musicians performed no differently than non-AP musicians. The findings confirm the robust nature of the voice advantage and rule out explanations based on familiarity, practice, and motor representations.
Psychological profile of adolescent cyberbullying aggressors / Perfil psicosocial de adolescentes agresores de cyberbullying
Authors: Buelga Sofía , Iranzo Begoña , Cava María-Jesús , Torralba Eva
Published: April 2015

The aim of this study was to analyse adolescent cyberbullying aggressors’ psychosocial profiles, taking into account the psychosocial adjustment indicators of life satisfaction, non-conforming reputation, antisocial behaviours at school and antisocial behaviours in the community. The sample was made up of 877 Spanish students (48.6% boys and 51.4% girls) aged 11 to 17 ( M = 13.8, SD = 1.4). Three groups of adolescents were distinguished: severe cyberbullies, occasional cyberbullies and non-aggressor adolescents. Analysis of covariance results indicated differences between the two cyberbullying groups and non-aggressor adolescents. The severe cyberbullies, followed by occasional cyberbullies, showed the least adaptive psychosocial profiles, while non-aggressor adolescents obtained the most adaptive profiles. We also discuss the practical implications of these results.
Sildenafil versus Nitric Oxide for Acute Vasodilator Testing in Pulmonary Arterial Hypertension
Authors: Milger Katrin , Felix Janine F. , Voswinckel Robert , Sommer Natascha , Franco Oscar H. , Grimminger Friedrich , Reichenberger Frank , Seeger Werner , Ghofrani Hossein A. , Gall Henning
Published: April 2015

Vasoreactivity testing with inhaled NO is recommended for pulmonary arterial hypertension (PAH) because of its therapeutic and prognostic value. Sildenafil has acute pulmonary vasodilating properties, but its diagnostic and prognostic impact in PAH is unknown. Our objective was to compare acute vasodilating responses to sildenafil and those to NO during right heart catheterization and also their prognostic values in patients with PAH. Ninety‐nine patients with idiopathic PAH and 99 with associated PAH underwent vasoreactivity testing with NO and sildenafil. Only mild adverse effects of sildenafil, in the form of hypotension, were observed, at a rate of 4.5%. The acute responder rate was 8.1% for NO and 11.6% for sildenafil. The NO‐induced response in mean pulmonary arterial pressure and cardiac output correlated with the response to sildenafil. Thirteen patients were long‐term responders to calcium channel blockers (CCBs), and 3 of them were correctly identified by acute vasoreactivity test with both drugs. The specificity of the vasoreactivity test for identifying long‐term CCB responders was 88.9% for NO and 85.1% for sildenafil testing. A trend toward better survival was found in sildenafil and NO responders, compared with nonresponders. Use of sildenafil for vasoreactivity testing is safe. Sildenafil may be useful as alternative vasoreactivity‐testing agent, identifying the same number of long‐term CCB responders as NO. However, NO seems to be a more ideal testing drug because of its pharmacologic properties. Moreover, sildenafil vasoreactivity testing might contribute to an improved estimate of prognosis among patients with PAH.
Asymptotic limits of operators similar to normal operators
Authors: Gehér György
Published: April 2015

Sz.-Nagy’s famous theorem states that a bounded operator

T
T

which acts on a complex Hilbert space

H

\mathcal {H}

is similar to a unitary operator if and only if

T
T

is invertible and both

T
T

and

T

−
1

T^{-1}

are power bounded. There is an equivalent reformulation of that result which considers the self-adjoint iterates of

T
T

and uses a Banach limit

L
L

. In this paper first we present a generalization of the necessity part in Sz.-Nagy’s result concerning operators that are similar to normal operators. In the second part we provide a characterization of all possible strong operator topology limits of the self-adjoint iterates of those contractions which are similar to unitary operators and act on a separable infinite-dimensional Hilbert space. This strengthens Sz.-Nagy’s theorem for contractions.
A reduction of proof complexity to computational complexity for 𝐴𝐶⁰[𝑝] Frege systems
Authors: Krajíček Jan
Published: April 2015

We give a general reduction of lengths-of-proofs lower bounds for constant depth Frege systems in DeMorgan language augmented by a connective counting modulo a prime

p
p

(the so-called

A

C
0

[
p
]

AC^0[p]

Frege systems) to computational complexity lower bounds for search tasks involving search trees branching upon values of maps on the vector space of low degree polynomials over

F

p

{\textbf {F}_p}

.
Dérivabilité ponctuelle d’une intégrale liée aux fonctions de Bernoulli
Authors: de la Bretèche R. , Tenenbaum G.
Published: April 2015

Let

B
(
ϑ
)

B (\vartheta )

denote the first normalised Bernoulli function, and consider the series

f
(
ϑ
)
:=

∑

n
⩾
1

B
(
n
ϑ
)

/

n

f(\vartheta ):=\sum _{n\geqslant 1}B(n\vartheta )/n

. In a previous paper, we determined the set

E
∗

E^*

of those real numbers

ϑ
\vartheta

at which

f
(
ϑ
)

f(\vartheta )

converges. Let

B
2

(
ϑ
)

B_2(\vartheta )

designate the second Bernoulli function and let

⟨
t
⟩

\langle t\rangle

denote the fractional part of the real number

t
t

. Put
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper F left-parenthesis theta right-parenthesis colon equals sigma-summation Underscript n greater-than-or-slanted-equals 1 Endscripts upper B 2 left-parenthesis n theta right-parenthesis slash 2 n squared equals pi squared slash 72 plus integral Subscript 0 Superscript theta Baseline f left-parenthesis t right-parenthesis normal d t period">

F
(
ϑ
)
:=

∑

n
⩾
1

B
2

(
n
ϑ
)

/

2

n
2

=

π
2

/

72
+

∫
0
ϑ

f
(
t
)

d

t
.

F(\vartheta ):=\sum _{n\geqslant 1}{B_2(n\vartheta )/ 2n^2}=\pi ^2/72+\int _0^\vartheta f(t)\mathrm {d} t.

It has been shown by Báez-Duarte, Balazard, Landreau and Saias (2005) that

F
(
ϑ
)

F(\vartheta )

and

∫
0
∞

⟨
t
⟩
⟨
ϑ
t
⟩

d

t

/

t
2

\int _0^\infty \langle t\rangle \langle \vartheta t\rangle \mathrm {d} t/t^2

have the same differentiability points. Moreover, using delicate functional equations, Balazard and Martin recently proved that the corresponding set is precisely

E
:=

E
∗

∖

Q

E:=E^*\smallsetminus \mathbb {Q}

and that

F
′

(
ϑ
)
=
f
(
ϑ
)

F’(\vartheta )=f(\vartheta )

whenever

ϑ
∈
E

\vartheta \in E

. We provide a short, direct proof of this last result, based on standard results from Diophantine approximation theory and uniform distribution theory.
Delta-shock wave type solution of hyperbolic systems of conservation laws
Authors: Danilov V. , Shelkovich V.
Published: April 2015

For two classes of hyperbolic systems of conservation laws new definitions of a

δ
\delta

-shock wave type solution are introduced. These two definitions give natural generalizations of the classical definition of the weak solutions. It is relevant to the notion of

δ
\delta

-shocks. The weak asymptotics method developed by the authors is used to describe the propagation of

δ
\delta

-shock waves to the three types of systems of conservation laws and derive the corresponding Rankine–Hugoniot conditions for

δ
\delta

-shocks.
Asymptotic approximation of singularly perturbed convection-diffusion problems with discontinuous derivatives of the Dirichlet data
Authors: López José , Sinusía Ester
Published: April 2015

We consider a singularly perturbed convection-diffusion equation,

−
ϵ
△
u
+

v
→

⋅

∇
→

u
=
0

-\epsilon \bigtriangleup u +\overrightarrow v\cdot \overrightarrow \nabla u=0

, defined on two domains: a quarter plane,

(
x
,
y
)
∈
(
0
,
∞
)
×
(
0
,
∞
)

(x,y)\in (0,\infty )\times (0,\infty )

, and a half plane,

(
x
,
y
)
∈
(
−
∞
,
∞
)
×
(
0
,
∞
)

(x,y)\in (-\infty ,\infty )\times (0,\infty )

. We consider for these problems Dirichlet boundary conditions with discontinuous derivatives at some points of the boundary. We obtain for each problem an exact representation of the solution in the form of an integral. From this integral we derive an asymptotic expansion of the solution when the singular parameter

ϵ
→

0
+

\epsilon \to 0^+

(with fixed distance

r
r

to the points of discontinuity of the boundary condition). It is shown that, in both problems, the first term of the expansion contains the primitive of an error function. This term characterizes the effect of the discontinuities on the

ϵ
−

\epsilon -

behaviour of the solution and its derivatives in the boundary or internal layers.
Contact problem for a wedge-shaped elastic solid in antiplane shear stress distribution
Authors: Singh B. , Rokne J. , Dhaliwal R.
Published: April 2015

The three-part mixed boundary value contact problem for a wedge-shaped region has been solved with the aid of Mellin transforms. Closed form expression for shear stress has been obtained. Finally, numerical results for shear stress and the resultant contact pressure have been obtained and interpreted.
On the derivation of boundary conditions from the global principles of continuum mechanics
Authors: Kleinstein Gerald
Published: April 2015

We consider the motion of a fluid exterior to a moving rigid obstacle, or interior to a moving rigid shell. The boundary conditions, such as the no-slip condition and the condition of an isothermal wall, applied in the solution of the system of differential equations describing these motions, are currently assumed to be an approximation derived from experimental observation rather than an exact law. It is the purpose of this paper to show that the boundary conditions at a material interface between a fluid and a solid are derivable from the global principles of balance of continuum mechanics and the Clausius-Duhem inequality.
Fundamental and singular solutions of Lamé equations for media with arbitrary elastic anisotropy
Authors: Kuznetsov Sergey
Published: April 2015

Fundamental and singular solutions of Lamé equations for media with arbitrary elastic anisotropy are constructed on the basis of multipolar expansions (expansions in spherical harmonics) of symbols and the corresponding operators. Theorems of convergence are formulated. A posteriori error estimates are presented.
𝐋¹ stability of semigroups with respect to their generators
Authors: Colombo Rinaldo , Gwiazda Piotr
Published: April 2015

This note is concerned with the

L

1

\mathbf {L}^1

–theory for the system

∂
t

u
=

div
x

⁡
A
(
u
)
+
B
⋅
Δ
u
+
C
(
u
)

\partial _t u = \operatorname {div}_x A(u) + B \cdot \Delta u + C(u)

in several space dimensions. First, an existence result is proved for data in

L

1

∩

L

∞

∩

B
V

\mathbf {L}^1\cap \mathbf {L}^\infty \cap \mathbf {BV}

. Then, the

L

1

\mathbf {L}^1

–Lipschitz dependence of the solutions with respect to the natural norms of 

A
A

,

B
B

and 

C
C

is achieved. As a corollary, the vanishing viscosity limit for conservation laws in 1D recently obtained in a work by Bianchini and Bressan is slightly extended.
Local uniqueness and continuation of solutions for the discrete Coulomb friction problem in elastostatics
Authors: Hild Patrick , Renard Yves
Published: April 2015

This work is concerned with the frictional contact problem governed by the Signorini contact model and the Coulomb friction law in static linear elasticity. We consider a general finite-dimensional setting and we study local uniqueness and smooth or nonsmooth continuation of solutions by using a generalized version of the implicit function theorem involving Clarke’s gradient. We show that for any contact status there exists an eigenvalue problem and that the solutions are locally unique if the friction coefficient is not an eigenvalue. Finally we illustrate our general results with a simple example in which the bifurcation diagrams are exhibited and discussed.
Convergence to equilibrium rarefaction waves for discontinuous solutions of shallow water wave equations with relaxation
Authors: Fan Haitao , Luo Tao
Published: April 2015

The purpose of this paper is to study the discontinuous solutions to a shallow water wave equation with relaxation. The typical initial value problem of discontinuous solutions is the Riemann problem. Unlike the homogeneous hyperbolic conservation laws, due to the inhomogeneity of the system studied here, the solutions of the Riemann problem do not have a self-similar structure anymore. This problem can be formulated as a free boundary problem. We show that the Riemann solutions still have a piecewise smooth structure globally and converge to the rarefaction waves of the equilibrium equation as time tends to infinity.
Transient temperature and elastic response of a space-based mirror in the radiation-conduction environment
Authors: Choudhury Bejoy
Published: April 2015

The problem of the one-dimensional heat equation with radiation boundary conditions is studied. Steady state and transient solutions for a space-based mirror are obtained under a broad class of boundary specification. Associated elastic stress and displacement are investigated. Time-varying heat flux at the boundary is also considered. The method requires solving equations of the type

tan
⁡
λ
=

(
B

i
1

+
B

i
2

)

λ

/

(

λ
2

−
B

i
1

B

i
2

)

\tan \lambda =\left (Bi_1+Bi_2\right )\lambda /\!\left (\lambda ^2-Bi_1Bi_2\right )

for the eigenvalues

λ
\lambda

, for which complete asymptotic solutions are given. Selected transient response results for temperature and stresses are presented.
𝐿^{𝑝}-𝐿^{𝑞} decay estimates for the Cauchy problem of linear thermoelastic systems with second sound in one space variable
Authors: Yang Lin , Wang Ya-Guang
Published: April 2015

L
p

−

L
q

L^p-L^q

decay estimates of solutions to the Cauchy problem of linear thermoelastic systems with second sound in one space variable will be studied in this paper. First, by dividing the frequency of phase space of the Fourier transformation into different regions, the asymptotic behavior of characteristic roots of the coefficient matrix is obtained by carefully analyzing the effect of the different regions. Second, with the help of the information on the characteristic roots and by using the interpolation theorem, the

L

p

−

L

q

L^{p}-L^{q}

decay estimate of solutions to the Cauchy problem of the linear thermoelastic system with second sound in one space variable is obtained.
Multiple bent cracks in an infinite orthotropic plate under an anti-plane shear stress
Authors: Singh B. , Rokne J. , Dhaliwal R.
Published: April 2015

The problem of bent cracks of finite length in an orthotropic plate subject to an arbitrary longitudinal shear is studied with the help of Mellin transforms. The case of constant shear stress is considered in detail. The final results of this paper are obtained in closed form, and the expressions for stress intensity factors and crack energy are obtained. The numerical results for stress intensity factors are given in tabular form.
When is a linear system conservative?
Authors: Malinen Jarmo , Staffans Olof , Weiss George
Published: April 2015

We consider infinite-dimensional linear systems without a-priori well-posedness assumptions, in a framework based on the works of M. Livšic, M. S. Brodskiĭ, Y. L. Smuljan, and others. We define the energy in the system as the norm of the state squared (other, possibly indefinite quadratic forms will also be considered). We derive a number of equivalent conditions for a linear system to be energy preserving and hence, in particular, well posed. Similarly, we derive equivalent conditions for a system to be conservative, which means that both the system and its dual are energy preserving. For systems whose control operator is one-to-one and whose observation operator has dense range, the equivalent conditions for being conservative become simpler, and reduce to three algebraic equations.
On stability of linear time-varying second-order differential equations
Authors: Duc Luu , Ilchmann Achim , Siegmund Stefan , Taraba Peter
Published: April 2015

We derive sufficient conditions for stability and asymptotic stability of second order, scalar differential equations with differentiable coefficients.
A way to compute the gravitational potential for near-spherical geometries
Authors: Grinfeld Pavel , Wisdom Jack
Published: April 2015

We use a boundary perturbation technique based on the calculus of moving surfaces to compute the gravitational potential for near-spherical geometries with piecewise constant densities. The perturbation analysis is carried out to third order in the small parameter. The presented technique can be adapted to a broad range of potential problems including geometries with variable densities and surface density distributions that arise in electrostatics. The technique is applicable to arbitrary small perturbations of a spherically symmetric configuration and, in principle, to arbitrary initial domains. However, the Laplace equation for an arbitrary domain can usually be solved only numerically. We therefore concentrate on spherical domains which yield a number of geophysical applications. As an illustration, we apply our analysis to the case of a near spherical triaxial ellipsoid and show that third order estimates for ellipticities such as that of the Earth are accurate to ten digits. We include an appendix that contains a concise, but complete, exposition of the tensor calculus of moving interfaces.
Diffusion of chemically reactive species in a porous medium
Authors: Vajravelu K. , Cannon J. , Rollins D.
Published: April 2015

Solutions for a class of nonlinear second-order differential equations, arising in diffusion of chemically reactive species of a Newtonian fluid immersed in a porous medium over an impervious stretching sheet, are obtained. Using the Schauder theory, existence and uniqueness results are established. Moreover, the exact analytical solutions (for some special cases) are obtained and are used to validate the numerical solutions. The results obtained for the diffusion characteristics reveal many interesting behaviors that warrant further study of the effects of reaction rate on the transfer of chemically reactive species.
Global solutions of the mean–field, very high temperature Caldeira–Leggett master equation
Authors: López José , Nieto Juanjo
Published: April 2015

In this paper, global well–posedness as well as regularity of very high temperature Caldeira–Leggett models with repulsive Poisson coupling are proved by using Green function techniques and Fokker–Planck smoothing arguments along with kinetic energy and elliptic estimates.
Exponential stability in linear viscoelasticity
Authors: Pata Vittorino
Published: April 2015

We address the study of the asymptotic behavior of solutions to an abstract integrodifferential equation modeling linear viscoelasticity. Framing the equation in the past history setting, we analyze the exponential stability of the related semigroup

S
(
t
)

S(t)

with dependence on the convolution kernel, providing a more general sufficient condition than the usual one present in the literature.
The exact region of oscillation for a first order neutral differential equation with delays
Authors: Cheng Sui , Lin Yi-zhong
Published: April 2015

The theory of envelopes is applied to yield the exact geometric region of oscillation for a class of first order neutral differential equation with delays. As examples, we show that the convex region of oscillation yield oscillation criteria that are sharp.
Finite-energy solutions of mixed 3d div-curl systems
Authors: Auchmuty Giles , Alexander James
Published: April 2015

This paper describes the existence and representation of certain finite energy

(

L
2

(L^2

-)solutions of weighted div-curl systems on bounded 3D regions with

C
2

C^2

-boundaries and mixed boundary data. Necessary compatibility conditions on the data for the existence of solutions are described. Subject to natural integrability assumptions on the data, it is then shown that there exist

L
2

L^2

-solutions whenever these compatibility conditions hold. The existence results are proved by using a weighted orthogonal decomposition theorem for

L
2

L^2

-vector fields in terms of scalar and vector potentials. This representation theorem generalizes the classical Hodge-Weyl decomposition. With this special choice of the potentials, the mixed div-curl problem decouples into separate problems for the scalar and vector potentials. Variational principles for the solutions of these problems are described. Existence theorems, and some estimates, for the solutions of these variational principles are obtained. The unique solution of the mixed system that is orthogonal to the null space of the problem is found and the space of all solutions is described. The second part of the paper treats issues concerning the non-uniqueness of solutions of this problem. Under additional assumptions, this space is shown to be finite dimensional and a lower bound on the dimension is described. Criteria that prescribe the harmonic component of the solution are investigated. Extra conditions that determine a well-posed problem for this system on a simply connected region are given. A number of conjectures regarding the results for bounded regions with handles are stated.
Asymmetric equilibrium configurations of hyperelastic cylindrical bodies under symmetric dead loads
Authors: Tarantino Angelo
Published: April 2015

Homogeneous deformations provided by the nonlinear equilibrium problem of symmetrically loaded isotropic hyperelastic cylindrical bodies are investigated. Depending on the form of the stored energy function, the problem considered may admit asymmetric solutions, besides the expected symmetric solutions. For general compressible materials, the mathematical condition allowing the assessment of these asymmetric solutions, which describe the global path of equilibrium branches, is given. Explicit expressions for evaluating critical loads and bifurcation points are derived. Results and basic relations obtained for general isotropic materials are then specialized for a Mooney-Rivlin and a neo-Hookean material. A broad numerical analysis is performed and the qualitatively more interesting asymmetric equilibrium branches are shown. The influence of the constitutive parameters is discussed, and, using the energy criterion, a number of considerations are carried out concerning the stability of the equilibrium solutions.
Existence and asymptotic analysis of a phase field model for supercooling
Authors: Klein Olaf , Luterotti Fabio , Rossi Riccarda
Published: April 2015

We prove an existence result for an initial-boundary value problem which models a perturbation of a phase transition phenomenon with supercooling effects. When the perturbation parameter goes to 0, an asymptotic analysis is performed. It leads to an existence result, in the framework of Young measures, for a slight modification of the original problem.
Spatial behavior for a fourth-order dispersive equation
Authors: Quintanilla Ramon , Saccomandi Giuseppe
Published: April 2015

In this note we investigate the spatial behavior of a linear equation of fourth order which models several mechanical situations when dispersive and dissipative effects are taken into account. In particular, this equation models the extensional vibration of a bar when we assume that external friction, with a rough substrate for example, is present. We show that for such an equation a Phragmén-Lindelöf alternative of exponential type can be obtained. A bound for the amplitude term in terms of boundary data is obtained. Moreover, when friction is absent, we obtain exponential decay results in the case of harmonic vibrations and we prove a polynomial decay estimate for general solutions.
Multiplicity of asymmetric solutions for nonlinear elliptic problems
Authors: Cao Daomin , Noussair Ezzat , Yan Shusen
Published: April 2015

In this paper we study the existence of multiple asymmetric positive solutions for the following symmetric problem:
\[
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="StartLayout Enlarged left-brace 1st Row 1st Column minus normal upper Delta u plus left-parenthesis lamda minus h left-parenthesis x right-parenthesis right-parenthesis u equals left-parenthesis 1 minus f left-parenthesis x right-parenthesis right-parenthesis u Superscript p Baseline comma 2nd Column a m p semicolon x element-of double-struck upper R Superscript upper N Baseline comma 2nd Row 1st Column u left-parenthesis x right-parenthesis greater-than 0 comma 2nd Column a m p semicolon x element-of double-struck upper R Superscript upper N Baseline comma 3rd Row 1st Column u element-of upper H Superscript 1 Baseline left-parenthesis double-struck upper R Superscript upper N Baseline right-parenthesis comma EndLayout">

{

−
Δ
u
+
(
λ
−
h
(
x
)
)
u
=
(
1
−
f
(
x
)
)

u
p

,

a
m
p
;
x
∈

R

N

,

u
(
x
)
>
0
,

a
m
p
;

x
∈

R

N

,

u
∈

H
1

(

R

N

)
,

\begin {cases} -\Delta u+(\lambda -h(x))u=(1-f(x))u^p, & x\in \mathbb {R}^N,\\ u(x)>0, &\quad x\in \mathbb {R}^N,\\ u\in H^1(\mathbb {R}^N), \end {cases}

\]
where

λ
>
0

\lambda >0

is a parameter,

h
(
x
)

h(x)

and

f
(
x
)

f(x)

are nonnegative radially symmetric functions in

L
∞

(

R

N

)

L^\infty (\mathbb {R}^N)

,

h
(
x
)

h(x)

and

f
(
x
)

f(x)

have compact support in

R

N

\mathbb {R}^N

,

f
(
x
)
≤
1

f(x)\leq 1

for all

x
∈

R

N

x\in \mathbb {R}^N

,

1
>
p
>
+
∞

1>p>+\infty

for

N
=
1
,
2

N=1,2

,

1
>
p
>

N
+
2

N
−
2

1>p>\frac {N+2}{N-2}

for

N
≥
3

N\geq 3

. We prove that for any

k
=
1
,
2
,

…

k=1,2,\,\ldots \,

, if

λ
\lambda

is large enough the above problem has positive solutions

u
λ

u_\lambda

concentrating at

k
k

distinct points away from the origin as

λ
\lambda

goes to

∞
\infty

.
Elliptic equations with diffusion coefficient vanishing at the boundary: Theoretical and computational aspects
Authors: Lee Chung-min , Rubinstein Jacob
Published: April 2015

A class of degenerate elliptic PDEs is considered. Specifically, it is assumed that the diffusion coefficient vanishes on the boundary of the domain. It is shown that if the diffusion coefficient vanishes fast enough, then the problem has a unique solution in the class of smooth functions even if no boundary conditions are supplied. A numerical method is derived to compute solutions for such degenerate equations. The problem is motivated by a certain approach to the recovery of the phase of a wave from intensity measurements.
Thin elastic films: The impact of higher order perturbations
Authors: Fonseca Irene , Francfort Gilles , Leoni Giovanni
Published: April 2015

The asymptotic behavior of an elastic thin film penalized by a van der Wals type interfacial energy is investigated when both its thickness and the magnitude of the additional energy vanish in the limit. Keeping track of both mid-plane and out-of-plane deformations (through the introduction of the Cosserat vector), the resulting behavior strongly depends upon the ratio between thickness and interfacial energy.
Free vibrations of a polar body at elastic range
Authors: Altay Gülay , Dökmeci M.
Published: April 2015

The purpose of this paper is to study certain features of the equations governing the time-harmonic free vibrations of a polar body at elastic range. The governing equations of micropolar elasticity are expressed in differential form, and then, the uniqueness of their solutions is investigated. The conditions sufficient for uniqueness are enumerated using the logarithmic convexity argument without any positive-definiteness assumptions of material elasticity. Applying a general principle of physics and modifying it through an involutory transformation, a unified variational principle is obtained that leads to all the governing equations of the free vibrations as its Euler-Lagrange equations. The governing equations are alternatively expressed in terms of the operators related to the kinetic and potential energies of the body. The basic properties of vibrations are studied and a variational principle in Rayleigh’s quotient is given. As an application, the high-frequency vibrations of an elastic plate are treated.
Jacobi fields in groups of diffeomorphisms and applications
Authors: Younes Laurent
Published: April 2015

This paper presents a series of applications of the Jacobi evolution equations along geodesics in groups of diffeomorphisms. We describe, in particular, how they can be used to perform implementable gradient descent algorithms for image matching, in several situations, and illustrate this with 2D and 3D experiments. We also discuss parallel translation in the group, and its projection on shape manifolds, and focus in particular on an implementation of these equations using iterated Jacobi fields.
Accurate calculation of the modified Mathieu functions of integer order
Authors: Van Buren Arnie , Boisvert Jeffrey
Published: April 2015

Several different expressions involving infinite series are available for calculating the radial (i.e., modified) Mathieu functions of integer order. Mathieu functions depend on three parameters: order, radial coordinate, and a size parameter that is chosen here to be either real or imaginary. Expressions traditionally used to calculate the radial functions result in inaccurate function values over some parameter ranges due to unavoidable subtraction errors that occur in the series evaluation. For many of the expressions the errors for small orders increase without bound as the size parameter increases. In the present paper, the subtraction error obtained using traditional expressions is explored with regard to parameter values. Included is a discussion of the Bessel function product series, which has an integer offset for the order of the Bessel functions that is traditionally chosen to be zero (or one). It is shown here that the use of larger offset values that tend to increase with increasing radial function order usually eliminates the subtraction errors. This paper identifies the expressions and evaluation procedures that provide accurate radial Mathieu function values. A brief discussion of the calculation of the angular functions of the first kind that appear in many of these expressions is included. The paper also gives a description of a Fortran computer program that provides accurate values of radial Mathieu functions together with the associated angular functions over extremely wide parameter ranges. This effort was guided by recent advancements in the calculation of prolate spheroidal functions. The Mathieu functions are a special case of spheroidal functions, resulting in a similarity of behavior in their evaluation.
Mild solutions for the relativistic Vlasov-Maxwell system for laser-plasma interaction
Authors: Bostan Mihai
Published: April 2015

We study a reduced

1
1

D Vlasov-Maxwell system which describes the laser-plasma interaction. The unknowns of this system are the distribution function of charged particles, satisfying a Vlasov equation, the electrostatic field, verifying a Poisson equation and a vector potential term, solving a nonlinear wave equation. The nonlinearity in the wave equation is due to the coupling with the Vlasov equation through the charge density. We prove here the existence and uniqueness of the mild solution (i.e., solution by characteristics) in the relativistic case by using the iteration method.
Viscoelastic fluids in a thin domain
Authors: Bayada G. , Chupin L. , Martin S.
Published: April 2015

The present paper deals with viscoelastic flows in a thin domain. In particular, we derive and analyse the asymptotic equations of the Stokes-Oldroyd system in thin films (including shear effects). We present a numerical method which solves the corresponding problem and we present some related numerical tests which evidence the effects of the elastic contribution on the flow.
From information scaling of natural images to regimes of statistical models
Authors: Wu Ying , Guo Cheng-En , Zhu Song-Chun
Published: April 2015

Vision can be considered a highly specialized data collection and analysis problem. We need to understand the special properties of natural image data in order to construct statistical models and develop statistical methods for representing and recognizing the wide variety of natural image patterns. One fundamental property of natural image data that distinguishes vision from other sensory tasks such as speech recognition is that scale plays a profound role in image formation and interpretation. Specifically, visual objects can appear at a wide range of scales in the images due to the change of viewing distance as well as camera resolution. The same objects appearing at different scales produce different image data with different statistical properties. In particular, we show that the entropy rate of the image data changes over scale. Moreover, the inferential uncertainty changes over scale too. We call these changes information scaling. We then examine both empirically and theoretically two prominent and yet largely isolated classes of image models, namely, wavelet sparse coding models and Markov random field models. Our results indicate that the two classes of models are appropriate for two different entropy regimes: sparse coding targets low entropy regimes, whereas Markov random fields are appropriate for high entropy regimes. Because information scaling connects different entropy regimes, both sparse coding and Markov random fields are necessary for representing natural image data, and information scaling triggers transitions between these two regimes. This motivates us to propose a modeling scheme that embraces both regimes of models in a common framework. The contribution of our work is two-fold. First, the study of information scaling provides a unifying perspective for the rich variety of natural image patterns. Second, the modeling scheme that we develop provides a natural integration of different regimes of image models.
The explicit solutions of linear left-invariant second order stochastic evolution equations on the 2D Euclidean motion group
Authors: Duits Remco , van Almsick Markus
Published: April 2015

We provide the solutions of linear, left-invariant, second order stochastic evolution equations on the 2D Euclidean motion group. These solutions are given by group-convolution with the corresponding Green’s functions which we derive in explicit form. A particular case coincides with the hitherto unsolved forward Kolmogorov equation of the so-called direction process, the exact solution of which is required in the field of image analysis for modeling the propagation of lines and contours. By approximating the left-invariant basis of the generators by left-invariant generators of a Heisenberg-type group, we derive simple, analytic approximations of the Green’s functions. We provide the explicit connection and a comparison between these approximations and the exact solutions. Finally, we explain the connection between the exact solutions and previous numerical implementations, which we generalize to cope with all linear, left-invariant, second order stochastic evolution equations.
On well-posedness, regularity and exact controllability for problems of transmission of plate equation with variable coefficients
Authors: Guo Bao-Zhu , Shao Zhi-Chao
Published: April 2015

A system of transmission of Euler-Bernoulli plate equation with variable coefficients under Neumann control and collocated observation is studied. Using the multiplier method on a Riemannian manifold, it is shown that the system is well-posed in the sense of D. Salamon. This establishes the equivalence between the exact controllability of an open-loop system and the exponential stability of a closed-loop system under the proportional output feedback. The regularity of the system in the sense of G. Weiss is also proved, and the feedthrough operator is found to be zero. These properties make this PDE system parallel in many ways to the finite-dimensional ones. Finally, the exact controllability of an open-loop system is developed under a uniqueness assumption by establishing the observability inequality for the dual system.
Existence and uniqueness result for the problem of viscous flow in a granular material with a void
Authors: Kohr Mirela , Sekhar G. P. Raja
Published: April 2015

The purpose of this paper is to obtain an indirect boundary integral formulation for the three-dimensional viscous flow problem in a granular material with a void. The corresponding existence and uniqueness result of the classical solution to this problem is proved by using the theory of hydrodynamic potentials.
A method of biological tissues elasticity reconstruction using magnetic resonance elastography measurements
Authors: Ammari Habib , Garapon Pierre , Kang Hyeonbae , Lee Hyundae
Published: April 2015

Magnetic resonance elastography (MRE) is an approach to measuring material properties using external vibration in which the internal displacement measurements are made with magnetic resonance. A variety of simple methods have been designed to recover mechanical properties by inverting the displacement data. Currently, the remaining problems with all of these methods are that, in general, the homogeneous Helmholtz equation is used and therefore it fails at interfaces between tissues of different properties. The purpose of this work is to propose a new method for reconstructing both the shape and the shear modulus of a small anomaly with Lamé parameters different from the background ones using internal displacement measurements.
Probabilistic recovery of neuroendocrine pulsatile, secretory and kinetic structure: An alternating discrete and continuous scheme
Authors: Chattopadhyay Somesh , Keenan Daniel , Veldhuis Johannes
Published: April 2015

The brain (hypothalamus) directs hormone secretion by the pituitary gland via burst-like (pulsatile) release of specific peptides at inferentially random times. These pulsatile signals supervise growth, reproduction, lactation, stress adaptations, water balance and immune responses. However, hypothalamic molecules are diluted

>
>

3000-fold in systemic blood, leaving pituitary-hormone pulses as measurable surrogates. The latter (roughly) mirror hypothalamic peptide bursts on a 1:1 basis, albeit being observed in a noisy environment. As a window to the brain, one must accurately recover the pulse (onset) times, and thereby estimate hormone secretion and kinetic parameters (

θ
∈

Θ
¯

\theta \in \overline {\Theta }

) without distortion. Based upon limited observed data, one would like to obtain probability statements about underlying pulsatility, secretion and kinetics. Moreover, to be applicable in today’s clinical setting, it is important that any such procedure require minimal or no human input. We propose and justify the following method. First, the data (a pituitary hormone concentration time-profile) is “selectively smoothed” by a nonlinear diffusion equation, whose diffusion coefficient is inversely related to the degree of rapid increase. This procedure generates a collection of potential pulse time sets

(

T

)

(\mathbb {T})

. Then, via an algorithm which alternates between a Metropolis algorithm on

T

\mathbb {T}

and a time-homogeneous diffusion process on

Θ
¯

\overline {\Theta }

, a compact manifold with boundary, simulation from an appropriately formulated (posterior) probability measure is achieved. The method is applied to recover the underlying structure of brain-pituitary regulation in disease and aging.