Gas morphology and energetics at the surface of PDRs: New insights with Herschel observations of NGC 7023

Context. We investigate the physics and chemistry of the gas and dust in dense photon-dominated regions (PDRs), along with their dependence on the illuminating UV field. Aims. Using Herschel/HIFI observations, we study the gas energetics in NGC 7023 in relation to the morphology of this nebula. NGC 7023 is the prototype of a PDR illuminated by a B2V star and is one of the key targets of Herschel. Methods. Our approach consists in determining the energetics of the region by combining the information carried by the mid-IR spectrum (extinction by classical grains, emission from very small dust particles) with that of the main gas coolant lines. In this letter, we discuss more specifically the intensity and line profile of the 158 μm (1901 GHz) [C ii] line measured by HIFI and provide information on the emitting gas. Results. We show that both the [C ii] emission and the mid-IR emission from polycyclic aromatic hydrocarbons (PAHs) arise from the regions located in the transition zone between atomic and molecular gas. Using the Meudon PDR code and a simple transfer model, we find good agreement between the calculated and observed [C ii] intensities. Conclusions. HIFI observations of NGC 7023 provide the opportunity to constrain the energetics at the surface of PDRs. Future work will include analysis of the main coolant line [O i] and use of a new PDR model that includes PAH-related species

Characteristics of Orality

In his book Orality and Literacy Father Ong listed a number of characteristics which are among "those which set off orally based thought and expression from chirographically and typographically based thought and expression, the characteristics, that is, which are most likely to strike those reared in writing and print cultures as surprising" (1982:36ff.). In this paper I should like to discuss several of these important characteristics in further depth in respect to their applicability to oral traditional literature, especially oral traditional poetry

Perspectives on Recent Work on the Oral Traditional Formula

The history of the study of Oral Literature has been covered well by John Miles Foley in his Introduction to Oral Traditional Literature (1981b), and also in his Introduction to Oral-Formulaic Theory and Research (1985), which includes a monumental annotated bibliography to the subject. I do not intend to recapitulate what he has already done so admirably; all the material is there, and his comments are even-handed and exemplary. There are, however, several general observations which it would perhaps be fitting to make at this juncture in the study of Oral Traditional Literature, which is marked by the inauguration of a new journal devoted to Oral Tradition. Perusing Foley's works just mentioned, one is immediately struck by the number of language traditions and cultural areas in which the "oral theory" is now discussed, and by the diversity of forms and problems included in the study of "oral traditional literature." This is an exciting development; it is also sobering, because it carries with it a mandate to be clear in our notion of what we mean by oral traditional literature.--Page 467.Albert B. Lord (Harvard University, Emeritus) truly needs no introduction for anyone working in the field of oral tradition. His comparative research, especially The Singer of Tales (1960), in effect established the Oral Theory as a method subsequently applied to dozens of different traditions. He is near completion of a sequel to that landmark volume

Non-diffracting Optical Beams in a Three-level Raman System

Diffractionless propagation of optical beams through atomic vapors is investigated. The atoms in the vapor are operated in a three-level Raman configuration. A suitably chosen control beam couples to one of the transitions, and thereby creates a spatially varying index of refraction modulation in the warm atomic vapor for a probe beam which couples to the other transition in the atoms. We show that a Laguerre-Gaussian control beam allows to propagate single Gaussian probe field modes as well as multi-Gaussian modes and non-Gaussian modes over macroscopic distances without diffraction. This opens perspectives for the propagation of arbitrary images through warm atomic vapors.Comment: 8 pages, 7 figure

Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein Condensates

We study the Kelvin mode excitations on a vortex line in a three-dimensional trapped Bose-Einstein condensate at finite temperature. Our stochastic Gross-Pitaevskii simulations show that the activation of these modes can be suppressed by tightening the confinement along the direction of the vortex line, leading to a strong suppression in the vortex decay rate as the system enters a regime of two-dimensional vortex dynamics. As the system approaches the condensation transition temperature we find that the vortex decay rate is strongly sensitive to dimensionality and temperature, observing a large enhancement for quasi-two-dimensional traps. Three-dimensional simulations of the recent vortex dipole decay experiment of Neely et al. [Phys. Rev. Lett. 104, 160401 (2010)] confirm two-dimensional vortex dynamics, and predict a dipole lifetime consistent with experimental observations and suppression of Kelvon-induced vortex decay in highly oblate condensates.Comment: 8 pages, 8 figure

Financial and non-financial information transfer and communication within small and medium enterprises

This participant-observation study explores the process of gathering and evaluating both financial and non-financial information and communication and transfer of that information within a medium-sized electrical service company in Christchurch, New Zealand. The previous literature has established the importance and the main characteristics of small and medium enterprises, mainly studying manufacturing companies. However, there has been little research done in New Zealand on the overall communication process and the financial and non-financial information usage in a small-medium enterprise. The Electrical Company has a flat structure which allows flexibility. The two owners understand the importance of financial management and use financial information extensively to ensure the business expenses are under control. The owners also gather and use non-financial information through talking to their accountant, their customers and people in the same industry and they keenly follow the news on the rebuilding of Christchurch after the recent earthquakes

The CHESS spectral survey of star forming regions: Peering into the protostellar shock L1157-B1 - II. Shock dynamics

Context. The outflow driven by the low-mass class 0 protostar L1157 is the prototype of the so-called chemically active outflows. The bright bowshock B1 in the southern outflow lobe is a privileged testbed of magneto-hydrodynamical (MHD) shock models, for which dynamical and chemical processes are strongly interdependent. Aims. We present the first results of the unbiased spectral survey of the L1157-B1 bowshock, obtained in the framework of the key program “Chemical HErschel Surveys of star forming regions” (CHESS). The main aim is to trace the warm and chemically enriched gas and to infer the excitation conditions in the shock region. Methods. The CO 5-4 and o-H2_O 1_(10)–1_(01) lines have been detected at high-spectral resolution in the unbiased spectral survey of the HIFI-band 1b spectral window (555–636 GHz), presented by Codella et al. in this volume. Complementary ground-based observations in the submm window help establish the origin of the emission detected in the main-beam of HIFI and the physical conditions in the shock. Results. Both lines exhibit broad wings, which extend to velocities much higher than reported up to now. We find that the molecular emission arises from two regions with distinct physical conditions : an extended, warm (100 K), dense (3 × 10^5 cm^(-3)) component at low-velocity, which dominates the water line flux in Band 1; a secondary component in a small region of B1 (a few arcsec) associated with high-velocity, hot (>400 K) gas of moderate density ((1.0–3.0) × 10^4 cm^(-3)), which appears to dominate the flux of the water line at 179μm observed with PACS. The water abundance is enhanced by two orders of magnitude between the low- and the high-velocity component, from 8 × 10^(-7) up to 8 × 10^(-5). The properties of the high-velocity component agree well with the predictions of steady-state C-shock models

Asymptotic behaviour of the Rayleigh--Taylor instability

We investigate long time numerical simulations of the inviscid Rayleigh-Taylor instability at Atwood number one using a boundary integral method. We are able to attain the asymptotic behavior for the spikes predicted by Clavin & Williams\cite{clavin} for which we give a simplified demonstration. In particular we observe that the spike's curvature evolves like $t^3$ while the overshoot in acceleration shows a good agreement with the suggested $1/t^5$ law. Moreover, we obtain consistent results for the prefactor coefficients of the asymptotic laws. Eventually we exhibit the self-similar behavior of the interface profile near the spike.Comment: 4 pages, 6 figure

Anti-Fall: A Non-intrusive and Real-time Fall Detector Leveraging CSI from Commodity WiFi Devices

Fall is one of the major health threats and obstacles to independent living for elders, timely and reliable fall detection is crucial for mitigating the effects of falls. In this paper, leveraging the fine-grained Channel State Information (CSI) and multi-antenna setting in commodity WiFi devices, we design and implement a real-time, non-intrusive, and low-cost indoor fall detector, called Anti-Fall. For the first time, the CSI phase difference over two antennas is identified as the salient feature to reliably segment the fall and fall-like activities, both phase and amplitude information of CSI is then exploited to accurately separate the fall from other fall-like activities. Experimental results in two indoor scenarios demonstrate that Anti-Fall consistently outperforms the state-of-the-art approach WiFall, with 10% higher detection rate and 10% less false alarm rate on average.Comment: 13 pages,8 figures,corrected version, ICOST conferenc