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

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

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

Mechanical properties of solid and porous stainless steel sheet material at elevated temperatures

A series of tensile tests in the temperature range from 20 o C to 1000 o C were carried out on three stainless steel sheet materials, namely D. T.D.166B, D. T. D. 171 and a woven porous material called Rigimesh. Values of Young's modulus, secant modulus, proof stress and ultimate stress were determined over the whole temperature range, and values of Poisson's ratio were determined at temperatures up to 500 o C. Room temperature tests were also carried out on the woven material at various orientations of the weave

Mechanical properties of solid and porous stainless steel sheet material at elevated temperatures

A series of tensile tests in the temperature range from 20 o C to 1000 o C were carried out on three stainless steel sheet materials, namely D. T.D.166B, D. T. D. 171 and a woven porous material called Rigimesh. Values of Young's modulus, secant modulus, proof stress and ultimate stress were determined over the whole temperature range, and values of Poisson's ratio were determined at temperatures up to 500 o C. Room temperature tests were also carried out on the woven material at various orientations of the weave

Adelbert Ames Soldier & Politician A Reevaluation

This article is a review of the military career of Adelbert Ames during the Civil War, Reconstruction and the Spanish-American War

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

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