Decay of Quasi-Particle in a Quantum Dot: the role of Energy Resolution

The disintegration of quasiparticle in a quantum dot due to the electron interaction is considered. It was predicted recently that above the energy \eps^{*} = \Delta(g/\ln g)^{1/2} each one particle peak in the spectrum is split into many components ($\Delta$ and $g$ are the one particle level spacing and conductance). We show that the observed value of \eps^{*} should depend on the experimental resolution \delta \eps. In the broad region of variation of \delta \eps the $\ln g$ should be replaced by \ln(\Delta/ g\delta \eps). We also give the arguments against the delocalization transition in the Fock space. Most likely the number of satellite peaks grows continuously with energy, being $\sim 1$ at \eps \sim \eps^{*}, but remains finite at \eps > \eps^{*}. The predicted logarithmic distribution of inter-peak spacings may be used for experimental confirmation of the below-Golden-Rule decay.Comment: 5 pages, REVTEX, 2 eps figures, version accepted for publication in Phys. Rev. Let

Chaos Thresholds in finite Fermi systems

The development of Quantum Chaos in finite interacting Fermi systems is considered. At sufficiently high excitation energy the direct two-particle interaction may mix into an eigen-state the exponentially large number of simple Slater-determinant states. Nevertheless, the transition from Poisson to Wigner-Dyson statistics of energy levels is governed by the effective high order interaction between states very distant in the Fock space. The concrete form of the transition depends on the way one chooses to work out the problem of factorial divergency of the number of Feynman diagrams. In the proposed scheme the change of statistics has a form of narrow phase transition and may happen even below the direct interaction threshold.Comment: 9 pages, REVTEX, 2 eps figures. Enlarged versio

Health professionals’ responses to women’s disclosure of domestic violence

This is the author's PDF version of an article published in Journal of Interpersonal Violence© 2014. The definitive version is available at http:dx.doi.org/10.1177/0886260514552449This study explored women’s experiences of their responses from health professionals following disclosure of domestic violence within a health setting. The existence of health based policies guiding professionals in the provision of appropriate support following disclosure of domestic violence is only effective if health professionals understand the dynamics of violent relationships. This paper focuses on the findings from the interviews conducted with fifteen women living in the UK who disclosed their experiences of domestic violence when accessing healthcare. Following thematic analysis, themes emerged that rotated around their disclosure and the responses they received from health professionals. The first two themes revealed the repudiation of, or recognition of and failure to act upon, domestic violence. A description of how the health professional’s behaviour became analogous with that of the perpetrator is discussed. The final theme illuminated women’s’ receipt of appropriate and sensitive support, leading to a positive trajectory away from a violent relationship. The findings suggest that the implicit understanding of the dynamics of violent relationships and the behaviours of the perpetrator of domestic violence are essential components of health care provision to avoid inadvertent inappropriate interactions with women

Suppression of Ground-State Magnetization in Finite-Sized Systems Due to Off-Diagonal Interaction Fluctuations

We study a generic model of interacting fermions in a finite-sized disordered system. We show that the off-diagonal interaction matrix elements induce density of states fluctuations which generically favor a minimum spin ground state at large interaction amplitude, $U$. This effect competes with the exchange effect which favors large magnetization at large $U$, and it suppresses this exchange magnetization in a large parameter range. When off-diagonal fluctuations dominate, the model predicts a spin gap which is larger for odd-spin ground states as for even-spin, suggesting a simple experimental signature of this off-diagonal effect in Coulomb blockade transport measurements.Comment: Final, substantially modified version of the article. Accepted for publication in Physical Review Letter

Quantum Dots with Disorder and Interactions: A Solvable Large-g Limit

We show that problem of interacting electrons in a quantum dot with chaotic boundary conditions is solvable in the large-g limit, where g is the dimensionless conductance of the dot. The critical point of the $g=\infty$ theory (whose location and exponent are known exactly) that separates strong and weak-coupling phases also controls a wider fan-shaped region in the coupling-1/g plane, just as a quantum critical point controls the fan in at T>0. The weak-coupling phase is governed by the Universal Hamiltonian and the strong-coupling phase is a disordered version of the Pomeranchuk transition in a clean Fermi liquid. Predictions are made in the various regimes for the Coulomb Blockade peak spacing distributions and Fock-space delocalization (reflected in the quasiparticle width and ground state wavefunction).Comment: 4 pages, 2 figure

Challenging Perceptions of Disability through Performance Poetry Methods: The "Seen but Seldom Heard" Project.

This paper considers performance poetry as a method to explore lived experiences of disability. We discuss how poetic inquiry used within a participatory arts-based research framework can enable young people to collectively question society’s attitudes and actions towards disability. Poetry will be considered as a means to develop a more accessible and effective arena in which young people with direct experience of disability can be empowered to develop new skills that enable them to tell their own stories. Discussion of how this can challenge audiences to critically reflect upon their own perceptions of disability will also be developed

Random Matrix Theory of Transition Strengths and Universal Magnetoconductance in the Strongly Localized Regime

Random matrix theory of the transition strengths is applied to transport in the strongly localized regime. The crossover distribution function between the different ensembles is derived and used to predict quantitatively the {\sl universal} magnetoconductance curves in the absence and in the presence of spin-orbit scattering. These predictions are confirmed numerically.Comment: 15 pages and two figures in postscript, revte

Ground-State Magnetization for Interacting Fermions in a Disordered Potential : Kinetic Energy, Exchange Interaction and Off-Diagonal Fluctuations

We study a model of interacting fermions in a disordered potential, which is assumed to generate uniformly fluctuating interaction matrix elements. We show that the ground state magnetization is systematically decreased by off-diagonal fluctuations of the interaction matrix elements. This effect is neglected in the Stoner picture of itinerant ferromagnetism in which the ground-state magnetization is simply determined by the balance between ferromagnetic exchange and kinetic energy, and increasing the interaction strength always favors ferromagnetism. The physical origin of the demagnetizing effect of interaction fluctuations is the larger number of final states available for interaction-induced scattering in the lower spin sectors of the Hilbert space. We analyze the energetic role played by these fluctuations in the limits of small and large interaction $U$. In the small $U$ limit we do second-order perturbation theory and identify explicitly transitions which are allowed for minimal spin and forbidden for higher spin. These transitions then on average lower the energy of the minimal spin ground state with respect to higher spin. For large interactions $U$ we amplify on our earlier work [Ph. Jacquod and A.D. Stone, Phys. Rev. Lett. 84, 3938 (2000)] which showed that minimal spin is favored due to a larger broadening of the many-body density of states in the low-spin sectors. Numerical results are presented in both limits.Comment: 35 pages, 24 figures - final, shortened version, to appear in Physical Review

Quantum Chaos Border for Quantum Computing

We study a generic model of quantum computer, composed of many qubits coupled by short-range interaction. Above a critical interqubit coupling strength, quantum chaos sets in, leading to quantum ergodicity of the computer eigenstates. In this regime the noninteracting qubit structure disappears, the eigenstates become complex and the operability of the computer is destroyed. Despite the fact that the spacing between multi-qubit states drops exponentially with the number of qubits $n$, we show that the quantum chaos border decreases only linearly with $n$. This opens a broad parameter region where the efficient operation of a quantum computer remains possible.Comment: revtex, 4 pages, 5 figures, more details and data adde

Machine learning based prediction of squamous cell carcinoma in ex vivo confocal laser scanning microscopy

Image classification with convolutional neural networks (CNN) offers an unprecedented opportunity to medical imaging. Regulatory agencies in the USA and Europe have already cleared numerous deep learning/machine learning based medical devices and algorithms. While the field of radiology is on the forefront of artificial intelligence (AI) revolution, conventional pathology, which commonly relies on examination of tissue samples on a glass slide, is falling behind in leveraging this technology. On the other hand, ex vivo confocal laser scanning microscopy (ex vivo CLSM), owing to its digital workflow features, has a high potential to benefit from integrating AI tools into the assessment and decision-making process. Aim of this work was to explore a preliminary application of CNN in digitally stained ex vivo CLSM images of cutaneous squamous cell carcinoma (cSCC) for automated detection of tumor tissue. Thirty-four freshly excised tissue samples were prospectively collected and examined immediately after resection. After the histologically confirmed ex vivo CLSM diagnosis, the tumor tissue was annotated for segmentation by experts, in order to train the MobileNet CNN. The model was then trained and evaluated using cross validation. The overall sensitivity and specificity of the deep neural network for detecting cSCC and tumor free areas on ex vivo CLSM slides compared to expert evaluation were 0.76 and 0.91, respectively. The area under the ROC curve was equal to 0.90 and the area under the precision-recall curve was 0.85. The results demonstrate a high potential of deep learning models to detect cSCC regions on digitally stained ex vivo CLSM slides and to distinguish them from tumor-free skin