To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.
High-energy electron radiography (HEER) has been proposed for time-resolved imaging of materials, high-energy density matter, and for inertial confinement fusion. The areal-density resolution, determined by the image intensity information is critical for these types of diagnostics. Preliminary experimental studies for different materials with the same thickness and the same areal-density target have been imaged and analyzed. Although there are some discrepancies between experimental and theory analysis, the results show that the density distribution can indeed be attained from HEER. The reason for the discrepancies has been investigated and indicates the importance of the uniformity in the transverse distribution beam illuminating the target. Furthermore, the method for generating a uniform transverse distribution beam using octupole magnets was studied and verified by simulations. The simulations also confirm that the octupole field does not affect the angle-position correlation in the center part beam, a critical requirement for the imaging lens. A more practical method for HEER using collimators and octupoles for generating more uniform beams is also described. Detailed experimental results and simulation studies are presented in this paper.
Here a compact three orthogonal planes high-energy electron radiography system was proposed. One of the critical technologies, the ultra-fast beam bunches split from the bunch train are studied. The separated bunches could be transported to the three orthogonal planes of the target for dynamic radiography diagnostics. The key elements of the ultra-fast bunches split system are transverse deflecting cavity (TDC) and the twin septum magnet (TSM). The principle of TDC and TSM are briefly introduced. An example of the beam bunches split system for test experiment (40 MeV electron beam) with TDC and TSM is designed and studied by particle-tracking simulation and it confirms this method is valid and feasible. Especially with TSM, a compact three orthogonal planes radiography system can be realized. The evolution of the beam parameters along the beam line from simulation are investigated. The detailed design of the beam split system and beam dynamics simulation study are presented in this paper.
We present a scheme of electron beam radiography to dynamically diagnose the high energy density (HED) matter in three orthogonal directions simultaneously based on electron Linear Accelerator. The dynamic target information such as, its profile and density could be obtained through imaging the scattered electron beam passing through the target. Using an electron bunch train with flexible time structure, a very high temporal evolution could be achieved. In this proposed scheme, it is possible to obtain 1010 frames/second in one experimental event, and the temporal resolution can go up to 1 ps, spatial resolution to 1 µm. Successful demonstration of this concept will have a major impact for both future inertial confinement fusion science and HED physics research.
Public health experts are concerned about the diminishing efficacy of antibiotics. Some have called for a ban on growth-promoting antibiotics in animal agriculture. This study identifies the contribution of growth-promoting antibiotics in the grower/finisher phase of U.S. pork production. With National Animal Health Monitoring System swine data, relationships are estimated between growth-promoting antibiotic use and productivity. Results indicate improvements in average daily gain (0.5%), feed conversion ratio (1.1%), and mortality rate (reduced 0.22 percentage points); these productivity improvements translate into a profitability gain of $0.59 per pig marketed, or an improvement of 9% in net profits associated with growth promotion antibiotics.
We combine econometric and financial analyses of the NAHMS 2000 Swine Survey data to examine whether evidence exists for reducing risk by using antibiotics for growth promotion (AGP) in the U.S. swine industry. A stochastic dominance analysis of alternative lengths of time (days) of AGP application reveals that AGP used in the range of 65–75 days is preferred by risk-averse producers. Risk is reduced and profits are increased from use of AGP. The combined impacts of increased average daily gain and decreased variability in pig live weight increase producer profits by $2.99 per pig marketed.
Asteroseismology, as a tool to use the indirect information contained in stellar oscillations to probe the stellar interiors, is an active field of research presently. Stellar age, as a fundamental property of star apart from its mass, is most difficult to estimate. In addition, the estimating of stellar age can provide the chance to study the time evolution of astronomical phenomena. In our poster, we summarize our previous work and further present a method to determine age of low-mass main-sequence star.
The standard AIC (Achromatic Interfero Coronagraph) has a “coudé” geometry (the output beam leaves at right angle from the input beam). Thus, some extra optical parts are required to fit such a device within the optical train between a telescope and its IR camera. To avoid this drawback, we present two mono-axial variants of the AIC.
We present new laboratory measurements of the intrinsic rejection performances in infrared (1.9 $\mu\,$m to 2.5 $\mu\,$m) for a prototype of Achromatic Interfero Coronagraph (AIC). We first recall basics about the AIC, then describe the prototype under consideration. We give detailed explanations about the experimental setup and the procedures followed to measure the rejection rate. We end up with a discussion of the results obtained.
Discriminating exo-planetary photons from stellar photons with a ground-based instrument is a physically interesting and challenging issue. We propose an observational technique based upon both spectral and polarimetric coding to discriminate the exo-planetary photons. We also discuss a preliminary observation run performed with the spectrograph “CARELEC” on the 193 cm telescope at the Observatoire de Haute provence (OHP).
Among the various recombination schemes devised for nulling interferometry, one is to use the Achromatic Interfero Coronograph (AIC) which basically is a modified Michelson-Fourier interferometer made compact by cementing together optical components.
The principle of this AIC is based on the focus-crossing property, from which a wave of light experiences an achromatic π phase shift when crossing a focus. Operated up to now only on a single telescope, this device is able to accomodate several beams for nulling. We describe the use of AIC as an interferometric nuller for a two-aperture interferometer.
The detection of a faint companion to a star with achromatic coronography
and adaptative optics is only limited by the residual speckles.
We study a method to increase the detectability of the companion, based
on the difference of two images taken in two different wavelengths, after
In this article I explore the imaginative and practical links that the Gitanos of Jarana, in Madrid, make with other Gitanos and Gypsies elsewhere. What kind of diaspora do they see themselves as belonging to? The context to my investigation is the fast growth of both Gypsy Pentecostalism and Roma international political activism – two movements that, in very different ways, call for the unity of all Gypsies/Roma worldwide. Their efforts contrast greatly with the world-views and attitudes of many of the people of Jarana who reject social harmony and cohesion as paths to community-making.
This issue is dedicated to Professor Sir John Meurig
Thomas for his renowned contributions to electron microscopy
in the chemical sciences. It is a collection of peer-reviewed
leading articles in electron microscopy, based on the presentations
at the Microscopy and Microanalysis (M&M) 2000 symposium,
which was held to honor Professor Thomas's exceptional
scientific leadership and wide-ranging fundamental contributions
in the chemical applications of electron microscopy.
Electron induced carbon deposition and etching was investigated by Auger electron spectroscopy in a custom designed vacuum system. The Auger electron spectrometer was used to provide a high flux electron beam to induce reactions and to monitor surface composition. During the e-beam induced deposition or etching, the gas phase pressure was 10-4 to 10-5 Torr. Several carbon precursors: benzene, cyclohexane and propane were used for deposition. The deposition rate depended on the precursor sticking coefficient and bonding structure. Among the three precursors tested, the deposition rate of carbon was cyclohexane > benzene > propane. The e-beam induced etching of carbon films was carried out in 1 × 10-4 torr oxygen ambient and the carbon film was prepared by reactive physical vapor deposition. The etching process can be divided into three stages: bulk film, interface, and substrate. For the bulk carbon film, the decrease of film thickness varies linearly with the e-beam flux, while at the interface, the film thickness shows an exponential decay with the electron flux. For the C in the Si substrate, a very slow etching rate was observed. The etching rate for bulk carbon film was ∼ 0.1 nm/min under the experimental conditions, which is equivalent tp 2.4 × 10-27 cm3/electron. At the interfacial region, the cross section of carbon removal by electrons was ∼ 4.6 × 10-21 cm2. Based on the change of the carbon line shape at the interface, we concluded that the etching rate is related to the chemical nature of the carbon species.