12,274 research outputs found

    On Homogeneous Decomposition Spaces and Associated Decompositions of Distribution Spaces

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    A new construction of decomposition smoothness spaces of homogeneous type is considered. The smoothness spaces are based on structured and flexible decompositions of the frequency space Rd\{0}\mathbb{R}^d\backslash\{0\}. We construct simple adapted tight frames for L2(Rd)L_2(\mathbb{R}^d) that can be used to fully characterise the smoothness norm in terms of a sparseness condition imposed on the frame coefficients. Moreover, it is proved that the frames provide a universal decomposition of tempered distributions with convergence in the tempered distributions modulo polynomials. As an application of the general theory, the notion of homogeneous α\alpha-modulation spaces is introduced.Comment: 27 page

    On a discrete transform of homogeneous decomposition spaces

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    We introduce almost diagonal matrices in the setting of (anisotropic) discrete homogeneous Triebel-Lizorkin type spaces and homogeneous modulation spaces, and it is shown that the class of almost diagonal matrices is closed under matrix multiplication. We then connect the results to the continuous setting and show that the "change of frame" matrix for a pair of time-frequency frames, with suitable decay properties, is almost diagonal. As an application of this result, we consider a construction of compactly supported frame expansions for homogeneous decomposition spaces of Triebel-Lizorkin type and for the associated modulation spaces.Comment: 30 page

    2012 Australian Census of Women in Leadership

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    A research book commissioned by the Australian Government Equal Opportunity Agency. This work reports the results of the 2012 Australian Census of Women in Leadership. The survey includes an analysis of the ASX 500 companies boards and executives gender diversity; gender diversity in public sector boards; and comparison with international initiatives in gender diversity in leadership positions. The work provides a detailed analysis of a large data base, and analytical commentary of the results. There is an assessment of remaining obstacles to achieving greater diversity, and analysis of what is required to create a better pipeline for the development of women for leadership

    An efficient quantum circuit analyser on qubits and qudits

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    This paper presents a highly efficient decomposition scheme and its associated Mathematica notebook for the analysis of complicated quantum circuits comprised of single/multiple qubit and qudit quantum gates. In particular, this scheme reduces the evaluation of multiple unitary gate operations with many conditionals to just two matrix additions, regardless of the number of conditionals or gate dimensions. This improves significantly the capability of a quantum circuit analyser implemented in a classical computer. This is also the first efficient quantum circuit analyser to include qudit quantum logic gates

    Hyperfine interaction induced decoherence of electron spins in quantum dots

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    We investigate in detail, using both analytical and numerical tools, the decoherence of electron spins in quantum dots (QDs) coupled to a bath of nuclear spins in magnetic fields or with various initial bath polarizations, focusing on the longitudinal relaxation in low and moderate field/polarization regimes. An increase of the initial polarization of nuclear spin bath has the same effect on the decoherence process as an increase of the external magnetic field, namely, the decoherence dynamics changes from smooth decay to damped oscillations. This change can be observed experimentally for a single QD and for a double-QD setup. Our results indicate that substantial increase of the decoherence time requires very large bath polarizations, and the use of other methods (dynamical decoupling or control of the nuclear spins distribution) may be more practical for suppressing decoherence of QD-based qubits.Comment: Rev. Tex, 5 pages, 3 eps color figures, submitted to Phys. Rev.

    Fungi, feather damage, and risk of predation

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    International audiencePredation is a powerful selective force with important effects on behavior, morphology , life history, and evolution of prey. Parasites may change body condition, health status, and ability to escape from or defend prey against predators. Once a prey individual has been detected, it can rely on a diversity of means of escape from the pursuit by the predator. Here we tested whether prey of a common raptor differed in terms of fungi from nonprey recorded at the same sites using the goshawk Accipiter gentilis and its avian prey as a model system. We found a positive association between the probability of falling prey to the raptor and the presence and the abundance of fungi. Birds with a specific composition of the community of fungi had higher probability of falling prey to a goshawk than individual hosts with fewer fungi. These findings imply that fungi may play a significant role in predator-prey interactions. The probability of having damaged feathers increased with the number of fungal colonies, and in particular the abundance of Myceliophthora verrucos and Schizophyllum sp. was positively related to the probability of having damaged feathers. In addition, we found a significant correlation between the rate of feather growth of goshawk prey with birds with more fungi being more likely to be depredated. These findings are consistent with the hypothesis that survival and feather quality of birds are related to abundance and diversity of fungi

    Transverse Momentum Spectra in Au+Au and d+Au Collisions at sNN\sqrt{s_{NN}}=200 GeV and the Pseudorapidity Dependence of High pT_T Suppression

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    We present spectra of charged hadrons from Au+Au and d+Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV measured with the BRAHMS experiment at RHIC. The spectra for different collision centralities are compared to spectra from p+pˉ{\rm p}+\bar{{\rm p}} collisions at the same energy scaled by the number of binary collisions. The resulting ratios (nuclear modification factors) for central Au+Au collisions at η=0\eta=0 and η=2.2\eta=2.2 evidence a strong suppression in the high pTp_{T} region (>>2 GeV/c). In contrast, the d+Au nuclear modification factor (at η=0\eta=0) exhibits an enhancement of the high pTp_T yields. These measurements indicate a high energy loss of the high pTp_T particles in the medium created in the central Au+Au collisions. The lack of suppression in d+Au collisions makes it unlikely that initial state effects can explain the suppression in the central Au+Au collisions.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let

    Rapidity Dependence of Charged Antiparticle-to-Particle Ratios in Au+Au Collisions at sNN=200\sqrt{s_{NN}}=200 GeV

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    We present ratios of the numbers of charged antiparticles to particles (pions, kaons and protons) in Au + Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV as a function of rapidity in the range yy=0-3. While the particle ratios at midrapidity are approaching unity, the K−/K+K^-/K^+ and pˉ/p\bar{p}/p ratios decrease significantly at forward rapidities. An interpretation of the results within the statistical model indicates a reduction of the baryon chemical potential from μB≈130\mu_B \approx 130MeV at yy=3 to μB≈25\mu_B \approx 25MeV at yy=0.Comment: 4 pages, 4 figure
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