Nanophotonic hybridization of narrow atomic cesium resonances and photonic stop gaps of opaline nanostructures

We study a hybrid system consisting of a narrowband atomic optical resonance and the long-range periodic order of an opaline photonic nanostructure. To this end, we have infiltrated atomic cesium vapor in a thin silica opal photonic crystal. With increasing temperature, the frequencies of the opal's reflectivity peaks shift down by >20% due to chemical reduction of the silica. Simultaneously, the photonic bands and gaps shift relative to the fixed near-infrared cesium D1 transitions. As a result the narrow atomic resonances with high finesse (f/df=8E5) dramatically change shape from a usual dispersive shape at the blue edge of a stop gap, to an inverted dispersion lineshape at the red edge of a stop gap. The lineshape, amplitude, and off-resonance reflectivity are well modeled with a transfer-matrix model that includes the dispersion and absorption of Cs hyperfine transitions and the chemically-reduced opal. An ensemble of atoms in a photonic crystal is an intriguing hybrid system that features narrow defect-like resonances with a strong dispersion, with potential applications in slow light, sensing and optical memory.Comment: 8 pages, 6 figure

Source population synthesis and the Galactic diffuse gamma-ray emission

Population synthesis is used to study the contribution from undetected sources to the Galactic ridge emission measured by EGRET. Synthesized source counts are compared with the 3rd EGRET catalogue at low and high latitudes. For pulsar-like populations, 5-10% of the emission >100 MeV comes from sources below the EGRET threshold. A steeper luminosity function can increase this to 20% without violating EGRET source statistics. Less luminous populations can produce much higher values without being detected. Since the unresolved source spectrum is different from the interstellar spectrum, it could provide an explanation of the observed MeV and GeV excesses above the predictions, and we give an explicit example of how this could work.Comment: Astrophysics and Space Science, in press. (Proceedings of Conference 'The multi-messenger approach to high-energy gamma-ray sources', Barcelona, 2006). Minor changes for accepted version, updated reference

The implications of climate change scenario selection for future streamflow projection in the Upper Colorado River Basin

The impact of projected 21st century climate conditions on streamflow in the Upper Colorado River Basin was estimated using a multi-model ensemble approach wherein the downscaled outputs of 112 future climate projections from 16 global climate models (GCMs) were used to drive a macroscale hydrology model. By the middle of the century, the impacts on streamflow range, over the entire ensemble, from a decrease of approximately 30% to an increase of approximately the same magnitude. Although prior studies and associated media coverage have focused heavily on the likelihood of a drier future for the Colorado River Basin, approximately 25 to 35% of the ensemble of runs, by 2099 and 2039, respectively, result in no change or increases in streamflow. The broad range of projected impacts is primarily the result of uncertainty in projections of future precipitation, and a relatively small part of the variability of precipitation across the projections can be attributed to the effect of emissions pathways. The simulated evolution of future temperature is strongly influenced by emissions, but temperature has a smaller influence than precipitation on flow. Period change statistics (i.e., the change in flow from one 30-yr period to another) vary as much within a model ensemble as between models and emissions pathways. Even by the end of the current century, the variability across the projections is much greater than changes in the ensemble mean. The relatively large ensemble analysis described herein provides perspective on earlier studies that have used fewer scenarios, and suggests that impact analyses relying on one or a few climate scenarios are unacceptably influenced by the choice of projections

The Effects Of Female Size On Fecundity In A Large Marine Gastropod Rapana Venosa (Muricidae)

The life history strategy of the veined rapa whelk Rapana venosa, a temperate marine gastropod, includes generation times of 1 y, individual longevity of \u3e 10 y, annual production of egg cases, and an adult size range of 40 to \u3e 160 mm shell length (SL). This life history combined with the animal\u27s generalist ecological preferences and broad physiological tolerances makes rapa whelks well suited for ecological success along a gradient of habitat and community types. Ballast water transport of veliger larvae across traditional zoogeographic boundaries has resulted in the establishment of invasive rapa whelk populations in Chesapeake Bay, USA, as well as European habitats. Although the need for a quantitative understanding of rapa whelk reproductive biology in terms of annual embryo production or fecundity is acknowledged as a necessary step in assessing the biological and ecological consequences of such an invasion, rapa whelk fecundity in relation to size for the entire adult size range (40-\u3e 160 mm SL) has not previously been quantified. The relationships between rapa whelk female size and egg case height, number of embryos egg case(-1), number of egg cases produced female whelk(-1) yr(-1) and fecundity, and the number of embryos female-(1) yr(-1), are described for a size range of individuals from Chesapeake Bay. In 2001 and 2003, egg laying began in mid to late May at water temperatures of approximately 18 degrees C and salinities 14-20 ppt and continued for 11-12 wk. The smallest rapa whelk observed (45 mm SL, 5.8 g wet tissue weight) laid egg cases with heights of approximately 7 mm. The largest whelk (163 mm SL, 220 g) laid egg cases with heights 30-33 mm. The number of embryos observed in egg cases produced by Chesapeake Bay rapa whelks ranged from 123 embryos in a 7.4 mm high egg case to 3,673 embryos in a 33.5 mm high egg case. Rapa whelk fecundity (number of embryos female(-1)yr(-1)) increased with female size. Egg case production was observed in rapa whelks that had hatched from egg cases and recruited within the previous year (\u3c 1 y old). Small (\u3c 80 mm SL, \u3c 28 g wet tissue weight) rapa whelks have relatively lower annual fecundities (1 x 10(5) embryos fernale(-1) yr(-1)) than large (\u3e 80 mm SL, \u3e 28 g wet tissue weight) rapa whelks that may produce between 1 x 10(6) and 4 x 10(6) embryos female(-1) yr(-1). Estimates of rapa whelk fecundity, even for small rapa whelks, are at least an order of magnitude greater than similar estimates for native United States Atlantic coast gastropods

The expectations and aspirations of a late-career professional woman

NoThis article presents a powerful account of one late-career woman's lived experiences. Little is known about women who continue professional careers into their 50s and beyond. Here insights are offered into her aspirations and expectations, as she reflects upon a career fragmented by gendered caring responsibilities and the implications of ageism and sexism together with health and body for her late-career phase. The narrative enhances understanding of the intersection of age and gender in a context where masculine career norms dominate. It also offers a reflection upon the implications of these themes for late-career women and their employing organizations more generally

Research encounters, reflexivity and supervision

Reflexivity in qualitative and ethnographic social science research can provide a rich source of data, especially regarding the affective, performative and relational aspects of interviews with research subjects. This paper explores by means of three case examples different ways of accessing and using such reflexivity. The examples are drawn from an empirical psycho-social study into the identity transitions of first-time mothers in an inner-city multicultural environment. Fieldnotes and supervision were used to engage with researcher subjectivity, to enhance the productive use of reflexivity and to address the emotional work of research. The methodology of the supervision was psychoanalytic, in its use of a boundaried frame and of psychoanalytic forms of noticing oneself, of staying engaged emotionally as well as creating a reflective distance. The examples illustrate how this can enhance the knowledge gained about the research subjects

Data mining: a tool for detecting cyclical disturbances in supply networks.

Disturbances in supply chains may be either exogenous or endogenous. The ability automatically to detect, diagnose, and distinguish between the causes of disturbances is of prime importance to decision makers in order to avoid uncertainty. The spectral principal component analysis (SPCA) technique has been utilized to distinguish between real and rogue disturbances in a steel supply network. The data set used was collected from four different business units in the network and consists of 43 variables; each is described by 72 data points. The present paper will utilize the same data set to test an alternative approach to SPCA in detecting the disturbances. The new approach employs statistical data pre-processing, clustering, and classification learning techniques to analyse the supply network data. In particular, the incremental k-means clustering and the RULES-6 classification rule-learning algorithms, developed by the present authors’ team, have been applied to identify important patterns in the data set. Results show that the proposed approach has the capability automatically to detect and characterize network-wide cyclical disturbances and generate hypotheses about their root cause