A Note on (Meta)stable Brane Configurations in MQCD

We examine the M-theory version of SQCD which is known as MQCD. In the IIA limit, this theory appears to have a supersymmetry-breaking brane configuration which corresponds to the meta-stable state of N=1 SU(Nc) SQCD. However, the behavior at infinity of this non-supersymmetric brane construction differs from that of the supersymmetric ground state of MQCD. We interpret this to mean that it is not a meta-stable state in MQCD, but rather a state in another theory. This provides a concrete example of the fact that, while MQCD accurately describes the supersymmetric features of SCQD, it fails to reproduce its non-supersymmetric features (such as meta-stable states) not only quantitatively but also qualitatively.Comment: 30 pages, 7 figures, harvmac. v2 typo correcte

Induced QCD and Hidden Local ZN Symmetry

We show that a lattice model for induced lattice QCD which was recently proposed by Kazakov and Migdal has a $Z_N$ gauge symmetry which, in the strong coupling phase, results in a local confinement where only color singlets are allowed to propagate along links and all Wilson loops for non-singlets average to zero. We argue that, if this model is to give QCD in its continuum limit, it must have a phase transition. We give arguments to support presence of such a phase transition

Quantifying integrated proteomic responses to iron stress in the globally important marine diazotroph trichodesmium

Trichodesmium is a biogeochemically important marine cyanobacterium, responsible for a significant proportion of the annual ‘new’ nitrogen introduced into the global ocean. These non-heterocystous filamentous diazotrophs employ a potentially unique strategy of near-concurrent nitrogen fixation and oxygenic photosynthesis, potentially burdening Trichodesmium with a particularly high iron requirement due to the iron-binding proteins involved in these processes. Iron availability may therefore have a significant influence on the biogeography of Trichodesmium. Previous investigations of molecular responses to iron stress in this keystone marine microbe have largely been targeted. Here a holistic approach was taken using a label-free quantitative proteomics technique (MSE) to reveal a sophisticated multi-faceted proteomic response of Trichodesmium erythraeum IMS101 to iron stress. Increased abundances of proteins known to be involved in acclimation to iron stress and proteins known or predicted to be involved in iron uptake were observed, alongside decreases in the abundances of iron-binding proteins involved in photosynthesis and nitrogen fixation. Preferential loss of proteins with a high iron content contributed to overall reductions of 55–60% in estimated proteomic iron requirements. Changes in the abundances of iron-binding proteins also suggested the potential importance of alternate photosynthetic pathways as Trichodesmium reallocates the limiting resource under iron stress. Trichodesmium therefore displays a significant and integrated proteomic response to iron availability that likely contributes to the ecological success of this species in the ocean

Evidence Against Instanton Dominance of Topological Charge Fluctuations in QCD

The low-lying eigenmodes of the Dirac operator associated with typical gauge field configurations in QCD encode, among other low-energy properties, the physics behind the solution to the $U_A(1)$ problem (i.e. the origin of the $\eta'$ mass), the nature of spontaneous chiral symmetry breaking, and the physics of string-breaking, quark-antiquark pair production, and the OZI rule. Moreover, the space-time chiral structure of these eigenmodes reflects the space-time topological structure of the underlying gauge field. We present evidence from lattice QCD on the local chiral structure of low Dirac eigenmodes leading to the conclusion that topological charge fluctuations of the QCD vacuum are not instanton-dominated. The result supports Witten's arguments that topological charge is produced by confinement-related gauge fluctuations rather than instantons.Comment: 35 pages, 11 figure

Towards a formalism for mapping the spacetimes of massive compact objects: Bumpy black holes and their orbits

Observations have established that extremely compact, massive objects are common in the universe. It is generally accepted that these objects are black holes. As observations improve, it becomes possible to test this hypothesis in ever greater detail. In particular, it is or will be possible to measure the properties of orbits deep in the strong field of a black hole candidate (using x-ray timing or with gravitational-waves) and to test whether they have the characteristics of black hole orbits in general relativity. Such measurements can be used to map the spacetime of a massive compact object, testing whether the object's multipoles satisfy the strict constraints of the black hole hypothesis. Such a test requires that we compare against objects with the ``wrong'' multipole structure. In this paper, we present tools for constructing bumpy black holes: objects that are almost black holes, but that have some multipoles with the wrong value. The spacetimes which we present are good deep into the strong field of the object -- we do not use a large r expansion, except to make contact with weak field intuition. Also, our spacetimes reduce to the black hole spacetimes of general relativity when the ``bumpiness'' is set to zero. We propose bumpy black holes as the foundation for a null experiment: if black hole candidates are the black holes of general relativity, their bumpiness should be zero. By comparing orbits in a bumpy spacetime with those of an astrophysical source, observations should be able to test this hypothesis, stringently testing whether they are the black holes of general relativity. (Abridged)Comment: 16 pages + 2 appendices + 3 figures. Submitted to PR

Exclusive 16O(γ,π-p) reaction in the Δ resonance region

We report the first exclusive (γ,π-p) measurements on a complex nucleus. The 16O(γ,π-p) reaction was measured at pion laboratory angles of 64° and 120°. Coincident protons were detected over the quasifree angular correlation range using a vertical array of seven plastic scintillator detectors spanning ±33° about the scattering plane. The cross sections are compared to factorized distorted-wave impulse approximation calculations; these provide a good description of the backward angle data, but are in serious disagreement with the forward angle data

Sum rule for the backward spin polarizability of the nucleon from a backward dispersion relation

A new sum rule for $\gamma_\pi$, the backward spin polarizability of the nucleon, is derived from a backward-angle dispersion relation. Taking into account single- and multi-pion photoproduction in the s-channel up to the energy 1.5 GeV and resonances in the t-channel with mass below 1.5 GeV, it is found for the proton and neutron that $[\gamma_\pi]_p$ = -39.5 +/- 2.4 and $[\gamma_\pi]_n$ = 52.5 +/- 2.4, respectively, in units of 10^{-4} fm^4.Comment: 10 pages, 1 figure, revtex. Submitted to Phys. Lett.

D-brane Decay in Two-Dimensional String Theory

We consider unstable D0-branes of two dimensional string theory, described by the boundary state of Zamolodchikov and Zamolodchikov [hep-th/0101152] multiplied by the Neumann boundary state for the time coordinate $t$. In the dual description in terms of the $c=1$ matrix model, this D0-brane is described by a matrix eigenvalue on top of the upside down harmonic oscillator potential. As suggested by McGreevy and Verlinde [hep-th/0304224], an eigenvalue rolling down the potential describes D-brane decay. As the eigenvalue moves down the potential to the asymptotic region it can be described as a free relativistic fermion. Bosonizing this fermion we get a description of the state in terms of a coherent state of the tachyon field in the asymptotic region, up to a non-local linear field redefinition by an energy-dependent phase. This coherent state agrees with the exponential of the closed string one-point function on a disk with Sen's marginal boundary interaction for $t$ which describes D0-brane decay.Comment: 19 pages, harvmac, minor change

Associations of prenatal maternal depressive symptoms with cord blood glucocorticoids and child hair cortisol levels in the project viva and the generation R cohorts:a prospective cohort study

Background: Prior studies have reported conflicting results regarding the association of prenatal maternal depression with offspring cortisol levels. We examined associations of high levels of prenatal depressive symptoms with child cortisol biomarkers. Methods:In Project Viva (n = 925, Massachusetts USA), mothers reported their depressive symptoms using the Edinburgh Postnatal Depression Scale (EPDS) during pregnancy, cord blood glucocorticoids were measured at delivery, and child hair cortisol levels were measured in mid-childhood (mean (SD) age: 7.8 (0.8) years) and early adolescence (mean (SD) age: 13.2 (0.9) years). In the Generation R Study (n = 1644, Rotterdam, The Netherlands), mothers reported depressive symptoms using the Brief Symptom Inventory (BSI) during pregnancy, and child hair cortisol was measured at a mean (SD) age of 6.0 (0.5) years. We used cutoffs of ≥ 13 for the EPDS and &gt; 0.75 for the BSI to indicate high levels of prenatal depressive symptoms. We used multivariable linear regression models adjusted for child sex and age (at outcome), and maternal pre-pregnancy BMI, education, social support from friends/family, pregnancy smoking status, marital status, and household income to assess associations separately in each cohort. We also meta-analyzed childhood hair cortisol results from both cohorts. Results: 8.0% and 5.1% of women respectively experienced high levels of prenatal depressive symptoms in Project Viva and the Generation R Study. We found no associations between high levels of maternal depressive symptoms during pregnancy and child cortisol biomarkers in either cohort. Conclusions: The present study does not find support for the direct link between high levels of maternal depressive symptoms and offspring cortisol levels.</p

Worldwide experience with a totally subcutaneous implantable defibrillator: Early results from the EFFORTLESS S-ICD registry

Aims The totally subcutaneous implantable-defibrillator (S-ICD) is a new alternative to the conventional transveno