78 research outputs found

    Lower bounds for the first eigenvalue of the magnetic Laplacian

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    We consider a Riemannian cylinder endowed with a closed potential 1-form A and study the magnetic Laplacian with magnetic Neumann boundary conditions associated with those data. We establish a sharp lower bound for the first eigenvalue and show that the equality characterizes the situation where the metric is a product. We then look at the case of a planar domain bounded by two closed curves and obtain an explicit lower bound in terms of the geometry of the domain. We finally discuss sharpness of this last estimate.Comment: Replaces in part arXiv:1611.0193

    On the homogeneity of a cobalt-based water oxidation catalyst

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    The homogeneity of molecular Co-based wateroxidation catalysts (WOCs) has been a subject of debate over thelast 10 years as assumed various homogeneous Co-based WOCswere found to actually form CoOxunder operating conditions. Thehomogeneity of the Co(HL)(HL=N,N-bis(2,2 '-bipyrid-6-yl)amine) system was investigated with cyclic voltammetry,electrochemical quartz crystal microbalance, and X-ray photo-electron spectroscopy. The obtained experimental results werecompared with heterogeneous CoOx. Although it is shown thatCo(HL) interacts with the electrode during electrocatalysis, theformation of CoOxwas not observed. Instead, a molecular depositof Co(HL) was found to be formed on the electrode surface. Thisstudy shows that deposition of catalytic material is not necessarilylinked to the decomposition of homogeneous cobalt-based water oxidation catalysts.Catalysis and Surface Chemistr

    Superparticle Models with Tensorial Central Charges

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    A generalization of the Ferber-Shirafuji formulation of superparticle mechanics is considered. The generalized model describes the dynamics of a superparticle in a superspace extended by tensorial central charge coordinates and commuting twistor-like spinor variables. The D=4 model contains a continuous real parameter a0a\geq 0 and at a=0 reduces to the SU(2,2|1) supertwistor Ferber-Shirafuji model, while at a=1 one gets an OSp(1|8) supertwistor model of ref. [1] (hep-th/9811022) which describes BPS states with all but one unbroken target space supersymmetries. When 0<a<1 the model admits an OSp(2|8) supertwistor description, and when a>1 the supertwistor group becomes OSp(1,1|8). We quantize the model and find that its quantum spectrum consists of massless states of an arbitrary (half)integer helicity. The independent discrete central charge coordinate describes the helicity spectrum. We also outline the generalization of the a=1 model to higher space-time dimensions and demonstrate that in D=3,4,6 and 10, where the quantum states are massless, the extra degrees of freedom (with respect to those of the standard superparticle) parametrize compact manifolds. These compact manifolds can be associated with higher-dimensional helicity states. In particular, in D=10 the additional ``helicity'' manifold is isomorphic to the seven-sphere.Comment: 32 pages, LATEX, no figure

    Hamiltonian structure and noncommutativity in pp-brane models with exotic supersymmetry

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    The Hamiltonian of the simplest super pp-brane model preserving 3/4 of the D=4 N=1 supersymmetry in the centrally extended symplectic superspace is derived and its symmetries are described. The constraints of the model are covariantly separated into the first- and the second-class sets and the Dirac brackets (D.B.) are constructed. We show the D.B. noncommutativity of the super pp-brane coordinates and find the D.B. realization of the OSp(18)OSp(1|8) superalgebra. Established is the coincidence of the D.B. and Poisson bracket realizations of the OSp(18)OSp(1|8) superalgebra on the constraint surface and the absence there of anomaly terms in the commutation relations for the quantized generators of the superalgebra.Comment: Latex, 27 pages, no figures. Latex packages amsfonts and euscript are use

    An innovative ethosuximide granule formulation designed for pediatric use: Comparative pharmacokinetics, safety, tolerability, and palatability profile versus reference syrup.

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    Ethosuximide, the first-line therapy for childhood absence epilepsy, is currently formulated as a syrup (Zarontin®, Pfizer) with a bitter taste and high sugar content, poorly adapted to children, and a ketogenic diet. The collaborative European FP7 project KIEKIDS aimed at developing an innovative sugar-free, tasteless formulation convenient for pediatric use. This dual Phase-I study evaluated two granule formulations based on lipid multiparticulate (LMP) technology. Two panels of 6 healthy adult volunteers underwent a randomized, placebo-controlled, partly blinded, 3-way cross-over trial, comparing ethosuximide granules A or B with placebo granules and syrup at single 10 mg/kg doses. Corresponding plasma pharmacokinetic profiles of ethosuximide were compared, along with palatability, safety, and tolerability. The LMP granule A proved suboptimal due to bitterness and adherence to beaker walls, while the optimized granule B revealed excellent palatability, similar to placebo granules, and low adherence to glass. The relative bioavailability of granules A versus syrup, based on dose-normalized C &lt;sub&gt;max&lt;/sub&gt; and AUC &lt;sub&gt;0-∞&lt;/sub&gt; was 93.7% [90% CI: 76.3-115.1] and 96.1% [91.0-101.5], respectively. For granules B it was 87.6% [81.6-94.0] and 92.5% [88.5-96.6], respectively, with slightly delayed t &lt;sub&gt;max&lt;/sub&gt; of 0.75 h [0.5-4.05] compared to syrup 0.5 h [0.3-0.8]. Tolerability visual analog scales revealed a trend for statistically non-significant improvement versus syrup at peak (30 min) for transient dizziness (both granules), fatigue (granules A), and anxiety (granules B). The innovative ethosuximide granule formulation B achieves a suitable profile for pediatric use, being sugar-free, tasteless, bioequivalent, and well-tolerated while enabling precise adjustment to body weight

    Supersymmetric string model with 30 kappa--symmetries in an extended D=11 superspace and 30/ 32 BPS states

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    A supersymmetric string model in the D=11 superspace maximally extended by antisymmetric tensor bosonic coordinates, Σ(52832)\Sigma^{(528|32)}, is proposed. It possesses 30 κ\kappa-symmetries and 32 target space supersymmetries. The usual preserved supersymmetry-κ\kappa-symmetry correspondence suggests that it describes the excitations of a BPS state preserving all but two supersymmetries. The model can also be formulated in any Σ(n(n+1)2n)\Sigma^{({n(n+1)\over 2}|n)} superspace, n=32 corresponding to D=11. It may also be treated as a `higher--spin generalization' of the usual Green--Schwarz superstring. Although the global symmetry of the model is a generalization of the super--Poincar\'e group, Σ(n(n+1)2n)×Sp(n){\Sigma}^{({n(n+1)\over 2}|n)}\times\supset Sp(n), it may be formulated in terms of constrained OSp(2n|1) orthosymplectic supertwistors. We work out this supertwistor realization and its Hamiltonian dynamics. We also give the supersymmetric p-brane generalization of the model. In particular, the Σ(52832)\Sigma^{(528|32)} supersymmetric membrane model describes excitations of a 30/32 BPS state, as the Σ(52832)\Sigma^{(528|32)} supersymmetric string does, while the supersymmetric 3-brane and 5-brane correspond, respectively, to 28/32 and 24/32 BPS states.Comment: 23 pages, RevTex4. V2: minor corrections in title and terminology, some references and comments adde

    Conformal Higher Spin Symmetries of 4d Massless Supermultiplets and osp(L,2M)osp(L,2M) Invariant Equations in Generalized (Super)Space

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    Realization of the conformal higher spin symmetry on the 4d massless field supermultiplets is given. The self-conjugated supermultiplets, including the linearized N=4{\cal N}=4 SYM theory, are considered in some detail. Duality between non-unitary field-theoretical representations and the unitary doubleton--type representations of the 4d conformal algebra su(2,2)su(2,2) is formulated in terms of a Bogolyubov transform. The set of 4d massless fields of all spins is shown to form a representation of sp(8)sp(8). The obtained results are extended to the generalized superspace invariant under osp(L,2M)osp(L, 2M) supersymmetries. World line particle interpretation of the free higher spin theories in the osp(2N,2M)osp(2\N, 2M) invariant (super)space is given. Compatible with unitarity free equations of motion in the osp(L,2M)osp(L,2M) invariant (super)space are formulated. A conjecture on the chain of AdSd+1/CFTdAdSd/CFTd1...AdS_{d+1}/CFT_d \to AdS_{d}/CFT_{d-1} \to ... dualities in the higher spin gauge theories is proposed.Comment: Latex, 63 pages; no figures.V2 Typos corrected, References updated. V3.Typos correced, references and an explanation on the relationship with previous work in section 4 are added. The version to appear in Phys.Rev.

    The Physics of the B Factories

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