The broad-band radio spectrum of LSI+61303 in outburst

Aims: Our aim is to explore the broad-band radio continuum spectrum of LSI+61303 during its outbursts by employing the available set of secondary focus receivers of the Effelsberg 100 m telescope. Methods: The clear periodicity of the system LSI+61303 allowed observations to be scheduled covering the large radio outburst in March-April 2012. We observed LSI+61303 on 14 consecutive days at 2.6, 4.85, 8.35, 10.45, 14.3, 23, and 32 GHz with a cadence of about 12 hours followed by two additional observations several days later. Based on these observations we obtained a total of 24 quasi-simultaneous broad-band radio spectra. Results: During onset, the main flare shows an almost flat broad-band spectrum, most prominently seen on March 27, 2012, where - for the first time - a flat spectrum (alpha=0.00+/-0.07, S nu^alpha) is observed up to 32 GHz (9 mm wavelength). The flare decay phase shows superimposed 'sub-flares' with the spectral index oscillating between -0.4 and -0.1 in a quasi-regular fashion. Finally, the spectral index steepens during the decay phase, showing optically thin emission with values alpha $\sim$ -0.5 to -0.7. Conclusions: The radio characteristics of LSI+61303 compare well with those of the microquasars XTE J1752-223 and Cygnus X-3. In these systems the flaring phase is actually also composed of a sequence of outbursts with clearly different spectral characteristics: a first outburst with a flat/inverted spectrum followed by a bursting phase of optically thin emission.Comment: 4 pages, 3 figures, accepted for publication in A&

Leadership Structure and Corporate Governance in Switzerland

The question of whether the CEO should also serve as chairman of the board is one of the most hotly debated issues in the recent corporate governance discussion. While agencytheoretic arguments advocate a separation of decision and control functions, the empirical evidence focusing on U.S. companies is not conclusive. In this context evidence from a country with a different practice of CEO succession may provide important new insights with respect to the question of whether one leadership structure should generally be preferred to the other one. This article fills this gap by investigating the valuation effects of leadership structure in Switzerland where – in contrast to the U.S. – a separation of the CEO and chairman functions is common. Consistent with the majority of prior research focusing on the U.S., the authors found no evidence of a systematic and significant difference in valuation between firms with combined and firms with separated functions. They also investigated whether leadership structure is related to firm-level corporate governance characteristics and found a similar curvilinear relationship between leadership structure and managerial shareholdings as is observed between firm value and managerial shareholdings. An implication is that possible agency costs associated with a combined function are mitigated by a higher incentive alignment of the CEO/chairman through an adequate level of managerial shareholdings. Over the last few years corporate governance became an important investment criterion, which is for example reflected in the emergence of various corporate governance ratings. The authors of this article additionally investigated whether firm value is significantly related to firm level corporate governance as measured by a broad survey-based index for a representative sample of Swiss firms. They documented a positive and significant relationship between the corporate governance index and firm valuation. This finding is robust to controlling for a series of additional governance mechanisms related to ownership structure, board characteristics, and leverage as well as a potential endogeneity of these mechanisms.Leadership structure; Firm valuation; Corporate governance; Managerial shareholdings

Evaluation of the importance of spin-orbit couplings in the nonadiabatic quantum dynamics with quantum fidelity and with its efficient "on-the-fly" ab initio semiclassical approximation

We propose to measure the importance of spin-orbit couplings (SOCs) in the nonadiabatic molecular quantum dynamics rigorously with quantum fidelity. To make the criterion practical, quantum fidelity is estimated efficiently with the multiple-surface dephasing representation (MSDR). The MSDR is a semiclassical method that includes nuclear quantum effects through interference of mixed quantum-classical trajectories without the need for the Hessian of potential energy surfaces. Two variants of the MSDR are studied, in which the nuclei are propagated either with the fewest-switches surface hopping or with the locally mean field dynamics. The fidelity criterion and MSDR are first tested on one-dimensional model systems amenable to numerically exact quantum dynamics. Then, the MSDR is combined with "on-the-fly" computed electronic structure to measure the importance of SOCs and nonadiabatic couplings (NACs) in the photoisomerization dynamics of CH2NH2+ considering 20 electronic states and in the collision of F + H2 considering six electronic states.Comment: 9 pages, 3 figures, submitted to J. Chem. Phy

Mitigating performance limitations of single beam-pipe circular e+e- colliders

Renewed interest in circular e+e- colliders has spurred designs of single beam-pipe machines, like the CEPC in China, and double beam pipe ones, such as the FCC-ee effort at CERN. Single beam-pipe designs profit from lower costs but are limited by the number of bunches that can be accommodated in the machine. We analyse these performance limitations and propose a solution that can accommodate O(1000) bunches while keeping more than 90% of the ring with a single beam pipe.Comment: Poster presented at IPAC'15, Richmond, VA, USA, May 201

Prospects for a Nuclear Optical Frequency Standard based on Thorium-229

The 7.6-eV-isomer of Thorium-229 offers the opportunity to perform high resolution laser spectroscopy of a nuclear transition. We give a brief review of the investigations of this isomer. The nuclear resonance connecting ground state and isomer may be used as the reference of an optical clock of very high accuracy using trapped and laser-cooled thorium ions, or in a compact solid-state optical frequency standard of high stability.Comment: 5 pages, 1 figure; Proceedings of the 7th Symposium on Frequency Standards and Metrology, 5-11 October 2008; reference added for section

The geometry of finite dimensional algebras with vanishing radical square

Let $\Lambda$ be a basic finite dimensional algebra over an algebraically closed field, with the property that the square of the Jacobson radical $J$ vanishes. We determine the irreducible components of the module variety $\text{Mod}_{\bf d}(\Lambda)$ for any dimension vector $\bf d$. Our description leads to a count of the components in terms of the underlying Gabriel quiver. A closed formula for the number of components when $\Lambda$ is local extends existing counts for the two-loop quiver to quivers with arbitrary finite sets of loops. For any algebra $\Lambda$ with $J^2 = 0$, our criteria for identifying the components of $\text{Mod}_{\bf d}(\Lambda)$ permit us to characterize the modules parametrized by the individual irreducible components. Focusing on such a component, we explore generic properties of the corresponding modules by establishing a geometric bridge between the algebras with zero radical square on one hand and their stably equivalent hereditary counterparts on the other. The bridge links certain closed subvarieties of Grassmannians parametrizing the modules with fixed top over the two types of algebras. By way of this connection, we transfer results of Kac and Schofield from the hereditary case to algebras of Loewy length $2$. Finally, we use the transit of information to show that any algebra of Loewy length $2$ which enjoys the dense orbit property in the sense of Chindris, Kinser and Weyman has finite representation type

The extrastriate body area computes desired goal states during action planning

How do object perception and action interact at a neural level? Here we test the hypothesis that perceptual features, processed by the ventral visuoperceptual stream, are used as priors by the dorsal visuomotor stream to specify goal-directed grasping actions. We present three main findings, which were obtained by combining time-resolved transcranial magnetic stimulation and kinematic tracking of grasp-and-rotate object manipulations, in a group of healthy human participants (N 22). First, the extrastriate body area (EBA), in the ventral stream, provides an initial structure to motor plans, based on current and desired states of a grasped object and of the grasping hand. Second, the contributions of EBA are earlier in time than those of a caudal intraparietal region known to specify the action plan. Third, the contributions of EBA are particularly important when desired and current object configurations differ, and multiple courses of actions are possible. These findings specify the temporal and functional characteristics for a mechanism that integrates perceptual processing with motor planning