Infrared absorption and emission characteristics of interstellar PAHs

The mid-infrared interstellar emission spectrum with features at 3.28, 6.2, 7.7, 8.7 and 11.3 microns is discussed in terms of the Polycyclic Aromatic Hydrocarbon (PAH) hypothesis, which is based on the suggestive, but inconclusive comparison between the interstellar emission spectrum with the infrared absorption and Raman spectra of a few PAHs. The fundamental vibrations of PAHs and PAH-like species which determine the IR and Raman properties are discussed. Interstellar IR band emission is due to relaxation from highly vibrationally excited PAHs excited by ultraviolet photons. The excitation/emission process is described and the IR fluorescence from one PAH, chrysene, is traced. Generally, there is sufficient energy to populate several vibrational levels in each mode. Molecular vibrational potentials are anharmonic and emission from these higher levels will fall at lower frequencies and produce weak features to the red of the stronger fundamentals. This process is also described and can account for some spectroscopic details of the interstellar emission spectra previously unexplained. Analysis of the interstellar spectrum shows that PAHs contain between 20 and 30 carbon atoms are responsible for the emission

Parametric study of manned life support systems. Volume 1 - Summary Final report, Jul. 1967 - Aug. 1968

Summary data on methodology, mission and vehicle criteria for parametric study of manned life support system

Geology of the Northern Llano Uplift, Junction to Llano, Texas

This year\u27s Texas Academy of Science Geology Field Trip will visit nine interesting locations in two different areas in the Texas Hill Country (Figure 1). In the first area we will look at the Cretaceous stratigraphy around Junction, Texas (Figures 1, 2, 3, and 4). The expedition will then travel to the northern part of the Llano uplift and study Cambrian and Precambrian stratigraphy and structure of the northern Llano Uplift (Figures 4 and 5). Stop 9 will be at Cooper’s BBQ for lunch

The hydrogen coverage of interstellar PAHs

The rate at which the CH bond in interstellar Polycyclic Aromatic Hydrocarbons (PAHs) rupture due to the absorption of a UV photon has been calculated. The results show that small PAHs (less than or equal to 25 carbon atoms) are expected to be partially dehydrogenated in regions with intense UV fields, while large PAHs (greater than or equal to 25 atoms) are expected to be completely hydrogenated in those regions. Because estimate of the carbon content of interstellar PAHs lie in the range of 20 to 25 carbon atoms, dehydrogenation is probably not very important. Because of the absence of other emission features besides the 11.3 micrometer feature in ground-based 8 to 13 micrometer spectra, it has been suggested that interstellar PAHs are partially dehydrogenated. However, IRAS 8 to 22 micrometer spectra of most sources that show strong 7.7 and 11.2 micrometer emission features also show a plateau of emission extending from about 11.3 to 14 micrometer. Like the 11.3 micrometer feature, this new feature is attributed to the CH out of plane bending mode in PAHs. This new feature shows that interstellar PAHs are not as dehydrogenated as estimated from ground-based 8 to 13 micrometer spectra. It also constrains the molecular structure of interstellar PAHs. In particular, it seems that very condensed PAHs, such as coronene and circumcoronene, dominate the interstellar PAH mixture as expected from stability arguments

Full Open Population Capture-Recapture Models with Individual Covariates

Traditional analyses of capture-recapture data are based on likelihood functions that explicitly integrate out all missing data. We use a complete data likelihood (CDL) to show how a wide range of capture-recapture models can be easily fitted using readily available software JAGS/BUGS even when there are individual-specific time-varying covariates. The models we describe extend those that condition on first capture to include abundance parameters, or parameters related to abundance, such as population size, birth rates or lifetime. The use of a CDL means that any missing data, including uncertain individual covariates, can be included in models without the need for customized likelihood functions. This approach also facilitates modeling processes of demographic interest rather than the complexities caused by non-ignorable missing data. We illustrate using two examples, (i) open population modeling in the presence of a censored time-varying individual covariate in a full robust-design, and (ii) full open population multi-state modeling in the presence of a partially observed categorical variable

Mediated intimacy: Sex advice in media culture

The bold argument of Mediated Intimacy (Barker et al., 2018)1 is that media of various kinds play an increasingly important role in shaping people’s knowledge, desires, practices and expectations about intimate relationships. While arguments rage about the nature and content of sex and relationship education in schools, it is becoming clear that more and more of us – young and old – look not to formal education, or even to our friends, for information about sex, but to the media (Albury, 2016; Attwood et al., 2015). This is not simply a matter of media ‘advice’ in the form of self-help books, magazine problem pages, or online ‘agony’ columns – though these are all proliferating and are discussed at length in the book. It is also about the wider cultural habitat of images, ideas and discourses about intimacy that circulate through and across media: the ‘happy endings’ of romantic comedies; the ‘money shots’ of pornography; the celebrity gossip about who is seeing whom, who is ‘cheating’, and who is looking ‘hot’; the lifestyle TV about ‘embarrassing bodies’ or being ‘undateable’; the newspaper features on how to have a ‘good’ divorce or ‘ten things never to say on a first date’; the new apps that incite us to quantify and rate our sex lives, and so forth. These constitute the ‘taken for granted’ of everyday understandings of intimacy, and they are at the heart of Mediated Intimacy

Analytical simulation of the Langley Research Center integrated life-support system, volume 1

Analytical simulation of integrated life support system and oxygen recovery syste

Sm-Nd isotopic systematics of the ancient Gneiss complex, southern Africa

In order to shed some new light on the question of the absolute and relative ages of the Ancient Gneiss Complex and Onverwacht Group, a Sm-Nd whole-rock and mineral isochron study of the AGC was begun. At this point, the whole-rock study of samples from the Bimodal Suite selected from those studied for their geochemical characteristics by Hunter et al., is completed. These results and their implications for the chronologic evolution of the Kaapvaal craton and the sources of these ancient rocks are discussed

Multiple uses of water in irrigated areas: a case study from Sri Lanka

Water management / Water allocation / Water use efficiency / Irrigated farming / Water resources development / Water policy / Water quality / Domestic water / Water users' associations / Water rights / Gender / Households / Pricing / Water costs / Case studies / Sri Lanka / Kirindi Oya

An Alternative Parameterization of R-matrix Theory

An alternative parameterization of R-matrix theory is presented which is mathematically equivalent to the standard approach, but possesses features which simplify the fitting of experimental data. In particular there are no level shifts and no boundary-condition constants which allows the positions and partial widths of an arbitrary number levels to be easily fixed in an analysis. These alternative parameters can be converted to standard R-matrix parameters by a straightforward matrix diagonalization procedure. In addition it is possible to express the collision matrix directly in terms of the alternative parameters.Comment: 8 pages; accepted for publication in Phys. Rev. C; expanded Sec. IV, added Sec. VI, added Appendix, corrected typo