9,811 research outputs found
Northern Ireland's longstanding record wind gust is almost certainly incorrect
Accurate assessment of record extreme wind gusts is important for building design standards and for industries such as insurance and forestry. Here, we show that the current record wind gust for Northern Ireland – 108kn (56ms−1) recorded at Kilkeel on 12 January 1974 – is almost certainly incorrect and may have arisen from an instrumental error or a power surge. We deduce this from direct anemograph inspection and from a variety of indirect supporting evidence. We recommend that other longstanding UK record wind gusts should also be independently re‐examined to assess their veracity
Does woman + a network = career progression?
Question: I am an ambitious and talented junior manager who has recently been hired by FAB plc, a large multinational company. I am also a woman and, as part of my induction pack, have received an invitation to join FABFemmes - the in-company women's network. I don't think my gender has been an obstacle to my success thus far and so I don't really feel the need to join. But on the other hand I don't want to turn my back on something that might offer me a useful source of contacts to help me advance up the career ladder. What would be the best thing to do? - Ms Ambitious, UK
ENVIRONMENTAL AND HEALTH STUDIES OF KENTUCKY BLACKBIRD ROOSTS
At the present time we are under contract from the Kentucky Environmental Quality Commission to study three aspects of Kentucky starling-blackbird roost problems: (1) a study of birds killed this coming winter through PA-14 treatments, to obtain more accurate data on species composition, sex ratios, kill success and food items; (2) a compilation of breeding and wintering data on Kentucky populations through analysis of U.S. Fish and Wildlife Service summer bird counts and banding returns; and (3) a study of spore dispersal of various fungal species, most notably Histoplasma capsulatum, from roost sites. The winter sampling is yet to be done, as sprayings most likely will not be undertaken until December. The analysis of population figures is complete and will be partially reported herein, as some data may be of significance for application to future management efforts. The histoplasmosis study began in June 1976 and will continue throughout the winter and spring; some preliminary results are deemed of significance to management efforts and are also reported herein
Supersymmetric Galileons
Galileon theories are of considerable interest since they allow for stable
violations of the null energy condition. Since such violations could have
occurred during a high-energy regime in the history of our universe, we are
motivated to study supersymmetric extensions of these theories. This is carried
out in this paper, where we construct generic classes of N=1 supersymmetric
Galileon Lagrangians. They are shown to admit non-equivalent stress-energy
tensors and, hence, vacua manifesting differing conditions for violating the
null energy condition. The temporal and spatial fluctuations of all component
fields of the supermultiplet are analyzed and shown to be stable on a large
number of such backgrounds. In the process, we uncover a surprising connection
between conformal Galileon and ghost condensate theories, allowing for a deeper
understanding of both types of theories.Comment: 41 pages, v2: added a referenc
Developing Primary Propulsion for the Ares I Crew Launch Vehicle and Ares V Cargo Launch Vehicle
In accordance with the U.S. Vision for Space Exploration, NASA has been tasked to send human beings to the moon, Mars, and beyond. The first stage of NASA's new Ares I crew launch vehicle (Figure 1), which will loft the Orion crew exploration vehicle into low-Earth orbit early next decade, will consist of a Space Shuttle-derived five-segment Reusable Solid Rocket Booster (RSRB); a pair of similar RSRBs also will be used on the Ares V cargo launch vehicle's core stage propulsion system. This paper will discuss the basis for choosing this particular propulsion system; describe the activities the Exploration Launch Projects (ELP) Office is engaged in at present to develop the first stage; and offer a preview of future development activities related to the first Ares l integrated test flight, which is planned for 2009
Ariel - Volume 3 Number 6
Editors
Richard J. Bonanno
Robin A. Edwards
Associate Editors
Steven Ager
Tom Williams
Lay-out Editor
Eugenia Miller
Contributing Editors
Paul Bialas
Robert Breckenridge
Lynne Porter
David Jacoby
Mike LeWitt
Terry Burt
Mark Pearlman
Michael Leo
Editors Emeritus
Delvyn C. Case, Jr.
Paul M. Fernhof
A Parameterized Centrality Metric for Network Analysis
A variety of metrics have been proposed to measure the relative importance of
nodes in a network. One of these, alpha-centrality [Bonacich, 2001], measures
the number of attenuated paths that exist between nodes. We introduce a
normalized version of this metric and use it to study network structure,
specifically, to rank nodes and find community structure of the network.
Specifically, we extend the modularity-maximization method [Newman and Girvan,
2004] for community detection to use this metric as the measure of node
connectivity. Normalized alpha-centrality is a powerful tool for network
analysis, since it contains a tunable parameter that sets the length scale of
interactions. By studying how rankings and discovered communities change when
this parameter is varied allows us to identify locally and globally important
nodes and structures. We apply the proposed method to several benchmark
networks and show that it leads to better insight into network structure than
alternative methods.Comment: 11 pages, submitted to Physical Review
Time-Varying Potassium in High-Resolution Spectra of the Type Ia Supernova 2014J
We present a time series of the highest resolution spectra yet published for
the nearby Type Ia supernova (SN) 2014J in M82. They were obtained at 11 epochs
over 33 days around peak brightness with the Levy Spectrograph (resolution
R~110,000) on the 2.4m Automated Planet Finder telescope at Lick Observatory.
We identify multiple Na I D and K I absorption features, as well as absorption
by Ca I H & K and several of the more common diffuse interstellar bands (DIBs).
We see no evolution in any component of Na I D, Ca I, or in the DIBs, but do
establish the dissipation/weakening of the two most blueshifted components of K
I. We present several potential physical explanations, finding the most
plausible to be photoionization of circumstellar material, and discuss the
implications of our results with respect to the progenitor scenario of SN
2014J.Comment: 11 pages, 8 figures, 3 tables, submitted to Ap
First-principles envelope-function theory for lattice-matched semiconductor heterostructures
In this paper a multi-band envelope-function Hamiltonian for lattice-matched
semiconductor heterostructures is derived from first-principles norm-conserving
pseudopotentials. The theory is applicable to isovalent or heterovalent
heterostructures with macroscopically neutral interfaces and no spontaneous
bulk polarization. The key assumption -- proved in earlier numerical studies --
is that the heterostructure can be treated as a weak perturbation with respect
to some periodic reference crystal, with the nonlinear response small in
comparison to the linear response. Quadratic response theory is then used in
conjunction with k.p perturbation theory to develop a multi-band effective-mass
Hamiltonian (for slowly varying envelope functions) in which all interface
band-mixing effects are determined by the linear response. To within terms of
the same order as the position dependence of the effective mass, the quadratic
response contributes only a bulk band offset term and an interface dipole term,
both of which are diagonal in the effective-mass Hamiltonian. Long-range
multipole Coulomb fields arise in quantum wires or dots, but have no
qualitative effect in two-dimensional systems beyond a dipole contribution to
the band offsets.Comment: 25 pages, no figures, RevTeX4; v3: final published versio
Time-resolved multi-mass ion imaging: femtosecond UV-VUV pump-probe spectroscopy with the PImMS camera
The Pixel-Imaging Mass Spectrometry (PImMS) camera allows for 3D charged
particle imaging measurements, in which the particle time-of-flight is recorded
along with position. Coupling the PImMS camera to an ultrafast
pump-probe velocity-map imaging spectroscopy apparatus therefore provides a
route to time-resolved multi-mass ion imaging, with both high count rates and
large dynamic range, thus allowing for rapid measurements of complex
photofragmentation dynamics. Furthermore, the use of vacuum ultraviolet
wavelengths for the probe pulse allows for an enhanced observation window for
the study of excited state molecular dynamics in small polyatomic molecules
having relatively high ionization potentials. Herein, preliminary time-resolved
multi-mass imaging results from CFI photolysis are presented. The
experiments utilized femtosecond UV and VUV (160.8~nm and 267~nm) pump and
probe laser pulses in order to demonstrate and explore this new time-resolved
experimental ion imaging configuration. The data indicates the depth and power
of this measurement modality, with a range of photofragments readily observed,
and many indications of complex underlying wavepacket dynamics on the excited
state(s) prepared
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