Orbital stability: analysis meets geometry

We present an introduction to the orbital stability of relative equilibria of Hamiltonian dynamical systems on (finite and infinite dimensional) Banach spaces. A convenient formulation of the theory of Hamiltonian dynamics with symmetry and the corresponding momentum maps is proposed that allows us to highlight the interplay between (symplectic) geometry and (functional) analysis in the proofs of orbital stability of relative equilibria via the so-called energy-momentum method. The theory is illustrated with examples from finite dimensional systems, as well as from Hamiltonian PDE's, such as solitons, standing and plane waves for the nonlinear Schr{\"o}dinger equation, for the wave equation, and for the Manakov system

Soliton Instabilities and Vortex Streets Formation in a Polariton Quantum Fluid

Exciton-polaritons have been shown to be an optimal system in order to investigate the properties of bosonic quantum fluids. We report here on the observation of dark solitons in the wake of engineered circular obstacles and their decay into streets of quantized vortices. Our experiments provide a time-resolved access to the polariton phase and density, which allows for a quantitative study of instabilities of freely evolving polaritons. The decay of solitons is quantified and identified as an effect of disorder-induced transverse perturbations in the dissipative polariton gas

Direct measure of the exciton formation in quantum wells from time resolved interband luminescence

We present the results of a detailed time resolved luminescence study carried out on a very high quality InGaAs quantum well sample where the contributions at the energy of the exciton and at the band edge can be clearly separated. We perform this experiment with a spectral resolution and a sensitivity of the set-up allowing to keep the observation of these two separate contributions over a broad range of times and densities. This allows us to directly evidence the exciton formation time, which depends on the density as expected from theory. We also evidence the dominant contribution of a minority of excitons to the luminescence signal, and the absence of thermodynamical equilibrium at low densities

Therapeutic Targeting of Glioblastoma and the Interactions with Its Microenvironment

Glioblastoma (GBM) is the most common primary malignant brain tumour, and it confers a dismal prognosis despite intensive multimodal treatments. Whilst historically, research has focussed on the evolution of GBM tumour cells themselves, there is growing recognition of the importance of studying the tumour microenvironment (TME). Improved characterisation of the interaction between GBM cells and the TME has led to a better understanding of therapeutic resistance and the identification of potential targets to block these escape mechanisms. This review describes the network of cells within the TME and proposes treatment strategies for simultaneously targeting GBM cells, the surrounding immune cells, and the crosstalk between them

High power femtosecond source based on passively mode-locked 1055nm VECSEL and Yb-fibre power amplifier

We report 5 ns pulses at 160 W average power and 910 repetition rate from a passively mode-locked VECSEL source seeding an Yb-doped fibre power amplifier. The amplified pulses were compressed to 291 fs duration

2s exciton-polariton revealed in an external magnetic field

We demonstrate the existence of the excited state of an exciton-polariton in a semiconductor microcavity. The strong coupling of the quantum well heavy-hole exciton in an excited 2s state to the cavity photon is observed in non-zero magnetic field due to surprisingly fast increase of Rabi energy of the 2s exciton-polariton in magnetic field. This effect is explained by a strong modification of the wave-function of the relative electron-hole motion for the 2s exciton state.Comment: 5 pages, 5 figure

Suicides in Psychiatric Patients: Identifying Health Care-Related Factors through Clinical Practice Reviews.

The objective of this study was to identify health care-related factors associated with death by suicide in psychiatric patients and to gain insight into clinician views on how to deal with suicidality. The study material derived from a clinician committee in a psychiatric department reviewing every outpatient and inpatient suicide in a standardized way. Reports' conclusions and corresponding plenary discussion minutes regarding 94 suicides were analyzed using inductive thematic content analysis. Health care-related factors were categorized into 4 themes: patient evaluation, patient management, clinician training, and involvement of relevant non-clinical partners. Clinician views on the themes were expressed through statements (i) promoting or restricting an aspect of care (here called recommendations), which mainly followed existing guidelines and were consensual and (ii) without precise indication (here called comments), which departed from mainstream opinions or addressed topics not covered by existing policy. Involvement of non-clinical partners emerged as a new key issue for suicide prevention in psychiatric departments and should be openly discussed with patients. Clinicians preferred balanced conclusions when they reviewed suicide cases

Global bifurcation for asymptotically linear Schr\"odinger equations

We prove global asymptotic bifurcation for a very general class of asymptotically linear Schr\"odinger equations \begin{equation}\label{1} \{{array}{lr} \D u + f(x,u)u = \lam u \quad \text{in} \ {\mathbb R}^N, u \in H^1({\mathbb R}^N)\setmimus\{0\}, \quad N \ge 1. {array}. \end{equation} The method is topological, based on recent developments of degree theory. We use the inversion $u\to v:= u/\Vert u\Vert_X^2$ in an appropriate Sobolev space $X=W^{2,p}({\mathbb R}^N)$, and we first obtain bifurcation from the line of trivial solutions for an auxiliary problem in the variables (\lambda,v) \in {\mathbb R} \x X. This problem has a lack of compactness and of regularity, requiring a truncation procedure. Going back to the original problem, we obtain global branches of positive/negative solutions 'bifurcating from infinity'. We believe that, for the values of $\lambda$ covered by our bifurcation approach, the existence result we obtain for positive solutions of \eqref{1} is the most general so fa