All AdS_7 solutions of type II supergravity

In M-theory, the only AdS_7 supersymmetric solutions are AdS_7 x S^4 and its orbifolds. In this paper, we find and classify new supersymmetric solutions of the type AdS_7 x M_3 in type II supergravity. While in IIB none exist, in IIA with Romans mass (which does not lift to M-theory) there are many new ones. We use a pure spinor approach reminiscent of generalized complex geometry. Without the need for any Ansatz, the system determines uniquely the form of the metric and fluxes, up to solving a system of ODEs. Namely, the metric on M_3 is that of an S^2 fibered over an interval; this is consistent with the Sp(1) R-symmetry of the holographically dual (1,0) theory. By including D8 brane sources, one can numerically obtain regular solutions, where topologically M_3 = S^3.Comment: 45 pages, 4 figures. v2: solution with single D8 added; references added; minor correction

A VLT study of metal-rich extragalactic H II regions. I. Observations and empirical abundances

We have obtained spectroscopic observations from 3600 Angstrom to 9200 Angstrom with FORS at the Very Large Telescope for approximately 70 H II regions located in the spiral galaxies NGC 1232, NGC 1365, NGC 2903, NGC 2997 and NGC 5236. These data are part of a project aiming at measuring the chemical abundances and characterizing the massive stellar content of metal-rich extragalactic H II regions. In this paper we describe our dataset, and present emission line fluxes for the whole sample. In 32 H II regions we measure at least one of the following auroral lines: [S II]4072, [N II]5755, [S III]6312 and [O II]7325. From these we derive electron temperatures, as well as oxygen, nitrogen and sulphur abundances, using classical empirical methods (both so-called "Te-based methods" and "strong line methods"). Under the assumption that the temperature gradient does not introduce severe biases, we find that the most metal-rich nebulae with detected auroral lines are found at 12+log(O/H)~8.9, i.e. about 60% larger than the adopted solar value. However, classical abundance determinations in metal-rich H II regions may be severely biased and must be tested with realistic photoionization models. The spectroscopic observations presented in this paper will serve as a homogeneous and high-quality database for such purpose.Comment: Accepted for publication in Astronomy and Astrophysic

AdS_6 solutions of type II supergravity

Very few AdS_6 x M_4 supersymmetric solutions are known: one in massive IIA, and two IIB solutions dual to it. The IIA solution is known to be unique; in this paper, we use the pure spinor approach to give a classification for IIB supergravity. We reduce the problem to two PDEs on a two-dimensional space Sigma. M_4 is then a fibration of S^2 over Sigma; the metric and fluxes are completely determined in terms of the solution to the PDEs. The results seem likely to accommodate near-horizon limits of (p,q)-fivebrane webs studied in the literature as a source of CFT_5's. We also show that there are no AdS_6 solutions in eleven-dimensional supergravity.Comment: 37 pages; v2: references and equations (5.1) added, version published in Journal of High Energy Physics; v3: equation (5.1b) correcte

REDD in the Carbon Market: A General Equilibrium Analysis

Deforestation is a major source of CO2 emissions, accounting for around 17% of total annual anthropogenic carbon release. While the cost estimates of reducing deforestation rates vary considerably depending on model assumptions, it is widely accepted that emissions reductions from avoided deforestation consist of a relatively low cost mitigation option. Halting deforestation is therefore not only a major ecological challenge, but also a great opportunity to cost effectively reduce climate change negative impacts. In this paper we analyze the impact of introducing avoided deforestation credits into the European carbon market using a multiregional Computable General Equilibrium model – the ICES model (Inter-temporal Computable Equilibrium System). Taking into account political concerns over a possible “flooding” of REDD credits, various limits to the number of REDD allowances entering the carbon market are considered. Finally, unlike previous studies, we account for both direct and indirect effects occurring on land and timber markets resulting from lower deforestation rates. We conclude that avoided deforestation notably reduces climate change policy costs - by approximately 80% with unlimited availability of REDD credits - and may drastically reduce carbon prices. Policy makers may, however, effectively control for these imposing limits to avoided deforestation credits use. Moreover, avoided deforestation has the additional positive effect of reducing carbon leakage of a unilateral European climate change policy. This is good news for the EU, but not necessarily for REDD regions. Indeed we show that REDD revenues are not sufficient to compensate REDD regions for a less leakage-affected and more competitive EU in international markets. In fact, REDD regions would prefer to free ride on the EU unilateral mitigation policy.Forestry, Avoided Deforestation, Climate Change, Emission Trading, General Equilibrium Modelling

Corporate governance and performance of Italian gambling SMEs during recession

Purpose: This study aims to explore how the economic recession and some corporate governance (CG) provisions can affect the performance of Italian gambling small and mediumsized enterprises (SMEs) across different business segments. Design/Methodology/approach: This study uses a panel sample of 2,135 observations before and during the global financial crisis. Specifically, the roles of ownership, boards of directors, CEO gender, and gambling business segments are investigated in the Italian gambling market. Findings: Ownership concentration has a negative relationship with the performance of foreigner- and financial-owned firms, while boards exert a positive role on performance. Interestingly, the financial crisis does not impact the performance of Italian gambling SMEs and some business segments, such as bingo, perform even better during the crisis. Research limitations/implications: Further investigations should analyze the role of single games on firm performance. The consumer- and firm-level examinations offer very different perspectives and scholars should be aware of this when investigating the gambling industry. Practical implications: This study might help both policymakers and other gambling firms, such as casinos, to better understand which appropriate CG model should be adopted and how it can positively influence performance, especially in recessionary times. Originality/value: This study contributes to studies on hospitality and tourism by focusing on the complementary role of gambling SMEs with respect to casinos. It also increases knowledge on the role of CG in privately owned gambling firms, which thus far has been scantly investigated by scholars

Towards weighing the condensation energy to ascertain the Archimedes force of vacuum

The force exerted by the gravitational field on a Casimir cavity in terms of Archimedes force of vacuum is discussed, the force that can be tested against observation is identified, and it is shown that the present technology makes it possible to perform the first experimental tests. The use of suitable high-Tc superconductors as modulators of Archimedes force is motivated. The possibility is analyzed of using gravitational wave interferometers as detectors of the force, transported through an optical spring from the Archimedes vacuum force apparatus to the gravitational interferometer test masses to maintain the two systems well separated. The use of balances to actuate and detect the force is also analyzed, the different solutions are compared, and the most important experimental issues are discussed.Comment: Revtex, 33 pages, 8 figures. In the final version, the title has been changed, and all sections have been improved, while 2 appendices have been adde

Laparoscopic Approach of a Unicornuate Uterus with Noncommunicating Rudimentary Horns

Background. Müllerian duct malformations delineate a miscellaneous group of congenital anomalies that result from arrested development, abnormal formation, or incomplete fusion of the mesonephric ducts. Case. This paper describes the diagnosis and management of a noncommunicating rudimentary horn complicated by severe pelvic pain and associated endometriosis. Conclusion. This condition was diagnosed by laparoscopy and hysteroscopy examination. Operative videolaparoscopy proved to be a successful approach for the treatment of this congenital Müllerian anomaly

A comparison of CMB Angular Power Spectrum Estimators at Large Scales: the TT case

In the context of cosmic microwave background (CMB) data analysis, we compare the efficiency at large scale of two angular power spectrum algorithms, implementing, respectively, the quadratic maximum likelihood (QML) estimator and the pseudo spectrum (pseudo-Cl) estimator. By exploiting 1000 realistic Monte Carlo (MC) simulations, we find that the QML approach is markedly superior in the range l=[2-100]. At the largest angular scales, e.g. l < 10, the variance of the QML is almost 1/3 (1/2) that of the pseudo-Cl, when we consider the WMAP kq85 (kq85 enlarged by 8 degrees) mask, making the pseudo spectrum estimator a very poor option. Even at multipoles l=[20-60], where pseudo-Cl methods are traditionally used to feed the CMB likelihood algorithms, we find an efficiency loss of about 20%, when we considered the WMAP kq85 mask, and of about 15% for the kq85 mask enlarged by 8 degrees. This should be taken into account when claiming accurate results based on pseudo-Cl methods. Some examples concerning typical large scale estimators are provided.Comment: 9 pages, 7 figures. Accepted for publication in MNRA