Characterizing the chemical pathways for water formation -- A deep search for hydrogen peroxide

In 2011, hydrogen peroxide (HOOH) was observed for the first time outside the solar system (Bergman et al., A&A, 2011, 531, L8). This detection appeared a posteriori quite natural, as HOOH is an intermediate product in the formation of water on the surface of dust grains. Following up on this detection, we present a search for HOOH in a diverse sample of sources in different environments, including low-mass protostars and regions with very high column densities, such as Infrared Dark Clouds (IRDCs). We do not detect the molecule in any other source than Oph A, and derive 3$\sigma$ upper limits for the abundance of HOOH relative to H$_2$ lower than in Oph A for most sources. This result sheds a different light on our understanding of the detection of HOOH in Oph A, and shifts the puzzle to why this source seems to be special. Therefore we rediscuss the detection of HOOH in Oph A, as well as the implications of the low abundance of HOOH, and its similarity with the case of O$_2$. Our chemical models show that the production of HOOH is extremely sensitive to the temperature, and favored only in the range 20$-$30 K. The relatively high abundance of HOOH observed in Oph A suggests that the bulk of the material lies at a temperature in the range 20$-$30 K.Comment: 18 pages, 3 figures, invited refereed paper at the Faraday Discussion 16

Squeezed pulsed light from a fiber ring interferometer

Observation of squeezed noise, 5 +/- 0.3 dB below the shot noise level, generated with pulses in a fiber ring interferometer is reported. The interferometric geometry is used to separate the pump pulse from the squeezed vacuum radiation. A portion of the pump is reused as the local oscillator in a homodyne detection. The pump fluctuations are successfully subtracted and shot noise limited performance is achieved at low frequencies (35-85 KHz). A possible utilization of the generated squeezed vacuum in improving a fiber gyro's signal to noise ratio is discussed

Employee Sentiment and Stock Option Compensation

The use of equity-based compensation for employees in the lower ranks of large organizations is a puzzle for standard economic theory: undiversified employees should discount company equity heavily, and any positive incentive effects should be diminished by free rider problems. We analyze whether the popularity of option compensation for rank and file employees may be driven by employee optimism. We develop a model of optimal compensation policy for a firm faced with employees with positive or negative sentiment, and explicitly take into account that current and potential employees are able to purchase equity in the firm through the stock market. We show that employee optimism by itself is insufficient to make equity compensation optimal for the firm. Any behavioral explanation for equity compensation based on employee optimism requires two ingredients: first, employees need be over-optimistic about firm value, and second, firms must be able to extract part of the implied rents even though employees can purchase company equity in the market. Such rent extraction becomes feasible if employees prefer the non-traded compensation options offered by firms to the traded equity offered by the market, or if the traded equity is overvalued. We then provide empirical evidence confirming that firms use broad-based option compensation when boundedly rational employees are likely to be excessively optimistic about company stock, and when employees are likely to have a strict preference for options over stock.

3-Oxabicyclo[3,2,0]hepta-1,4-diene

3-Oxabicyclo[3,2,0]hepta-1,4-diene (3) has been synthesized by partial hydrogenation of 3-oxabicyclo-[3,2,0]hepta-1,4,6-triene (2)

Coleman-Weinberg Mechanism and Interaction of D3-Branes in Type 0 String Theory

The low-energy theory on the world volume of parallel static D3-branes of type 0 strings is the Yang-Mills theory with six scalar fields in the adjoint representation. One-loop corrections in this theory induce Coleman-Weinberg effective potential, which can be interpreted as an interaction energy of D3-branes. The potential is repulsive at short distances and attractive at large ones. In the equilibrium, a large number of D3-branes forms a spherical shell with the radius proportional to the characteristic energy scale of the world-volume theory.Comment: 5 pages, LaTex, 1 figure; v2: Discussion of the interaction potential between D3-branes at short distances is modified, version to be published in Phys. Lett.

How younger students perceive and identify historical significance

Historical significance is a historical thinking concept. Being able to identify historical significance is viewed as important for understanding change and continuity in the past, and for understanding the way ‘history’ is constructed by present society. This article discusses how Swedish students in Grade 5 (age 11 years) perceive and understand historical significance without having received prior instruction on how to identify historical significance. The results show that the students see thrilling and exciting events in the past as significant, as well as the events, inventions, ideas and values that have influenced the present or changed the course of history in some way. In this paper, I compare students’ answers to definitions of historical significance formulated by Christine Counsell (2004) and Matthew Bradshaw (2006). For the study, 67 students were interviewed in semi-structured interviews in small groups. They attended six different schools in the middle part of Sweden and came from varying backgrounds. Regardless of their backgrounds or origins, the students see the history culture of the majority, as presented in their history education, as their own

Perturbation Theory for Singular Potentials in Quantum Mechanics

We study perturbation theory in certain quantum mechanics problems in which the perturbing potential diverges at some points, even though the energy eigenvalues are smooth functions of the coefficient of the potential. We discuss some of the unusual techniques which are required to obtain perturbative expansions of the energies in such cases. These include a point-splitting prescription for expansions around the Dirichlet (fermionic) limit of the $\delta$-function potential, and performing a similarity transformation to a non-Hermitian potential in the Calogero-Sutherland model. As an application of the first technique, we study the ground state of the $\delta$-function Bose gas near the fermionic limit.Comment: LaTeX, 19 pages, no figure