A variety of techniques used to obtain the mechanical properties of materials at high rates of strain (⩾10
s
−1) are summarised. These include dropweight machines, split Hopkinson pressure bars, ...Taylor impact and shock loading by plate impact. High-speed photography, particularly when used in association with optical techniques, is a key area and recent advances and applications to studies of ballistic impact are discussed. More comprehensive bibliographies and a fuller discussion of the history may be found in earlier reviews published by us in 1994, 1998 and 2001 (J Phys IV France 4 (C8) (1994) 3; Review of experimental techniques for high rate deformation studies, Proceedings of the Acoustics and Vibration Asia ’98, Acoustics and Vibration Asia 98 Conference, Singapore, 1998; Review of experimental techniques for high rate deformation and shock studies, New Experimental Methods in Material Dynamics and Impact, Institute of Fundamental Technological Research, Warsaw, Poland, 2001).
At the National Ignition Facility, inertial confinement fusion experiments aim to burn and ignite a hydrogen plasma to generate a net source of energy through the fusion of deuterium and tritium ...ions. The energy deposited by α-particles released from the deuterium–tritium fusion reaction plays the central role in heating the fuel to achieve a sustained thermonuclear burn. In the hydrodynamic picture, α-heating increases the temperature of the plasma, leading to increased reactivity because the mean ion kinetic energy increases. Therefore, the ion temperature is related to the mean ion kinetic energy. Here we use the moments of the neutron spectrum to study the relationship between the ion temperature (measured by the variance in the neutron kinetic energy spectrum) and the ion mean kinetic energy (measured by the shift in the mean neutron energy). We observe a departure from the relationship expected for plasmas where the ion relative kinetic energy distribution is Maxwell–Boltzmann, when the plasma begins to burn. Understanding the cause of this departure from hydrodynamic behaviour could be important for achieving robust and reproducible ignition.Inertial confinement fusion experiments reveal a departure from the expected hydrodynamic behaviour of a plasma when the fusion reactions become the primary source of plasma heating.
1. The management of migratory species is challenging because of insufficient data on long-range movement patterns, habitat use, and the impact of anthropogenic pressures (e.g. hunting) throughout ...their home ranges. 2. We evaluate the current abundance and mobility of the Malayan flying fox Pteropus vampyrus, a threatened fruit bat species of ecological and economic significance across Southeast Asia, using roost site surveys and satellite telemetry. We combined this with data from hunter license sales and population projection models to assess the impact and sustainability of current hunting practices in Peninsular Malaysia. 3. We monitored 33 active Pteropus vampyrus roost sites in Peninsular Malaysia, including eight seasonal roost sites. Roost site occupancy showed considerable temporal variation over the 3-year study period. 4. Hunting activity has more than doubled since 1996, and based on license sales, we estimate that a minimum legal harvest of 87 800 bats occurred between 2002 and 2005. Population models suggest that this level of hunting is likely to be unsustainable given our baseline abundance scenarios of 100 000, 250 000 or 500 000 bats, especially considering that these models do not include culling of Malayan flying foxes as agricultural pests or illegal hunting activities, for which there are no available data. 5. Satellite telemetry of seven adult male bats show that Malayan flying foxes are highly mobile, travelling hundreds of kilometres between roosting sites within a year and occupying home ranges that extend beyond Malaysia to include Indonesia and Thailand. We conclude that focal hunting pressure in Malaysia threatens a regional population of this migratory mammal. 6.Synthesis and applications. This is the first study of its kind on flying foxes in Asia, and illustrates that bats, like other migratory species, urgently require comprehensive protection by regional management plans across their range. P. vampyrus moves across international borders in Southeast Asia. Current hunting practices within Malaysia together with limited protection in other countries may threaten its long-term survival.
We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation of the Askaryan effect in ice. As part of the ...complete validation process for the ANITA experiment, we performed an experiment at the Stanford Linear Accelerator Center in June 2006 using a 7.5 metric ton ice target. We measure for the first time the large-scale angular dependence of the radiation pattern, a major factor in determining the solid-angle acceptance of ultrahigh-energy neutrino detectors.
We have used manganese-enhanced magnetic resonance imaging (MEMRI) to show distinct patterns of neuronal activation within the hypothalamus and brainstem of fasted mice in response to peripheral ...injection of the anorexigenic agents glucagon-like peptide-1 (GLP-1), oxyntomodulin (OXM) and lithium chloride. Administration of both GLP-1 and OXM resulted in a significant increase in signal intensity (SI) in the area postrema of fasted mice, reflecting an increase in neuronal activity within the brainstem. In the hypothalamus, GLP-1 administration induced a significant reduction in SI in the paraventricular nucleus and an increase in the ventromedial hypothalamic nucleus whereas OXM reduced SI in the arcuate and supraoptic nuclei of the hypothalamus. These data indicate that whilst these related peptides both induce a similar effect on neuronal activity in the brainstem they generate distinct patterns of activation within the hypothalamus. Furthermore, the hypothalamic pattern of signal intensity generated by GLP-1 closely matches that generated by peripheral injection of LiCl, suggesting the anorexigenic effects of GLP-1 may be in part transmitted via nausea circuits. This work provides a framework by which the temporal effects of appetite modulating agents can be recorded simultaneously within hypothalamic and brainstem feeding centres.
PDF
