We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
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 no-reply@cambridge.org
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.
Laser-driven neutron sources are routinely produced by the interaction of laser-accelerated protons with a converter. They present complementary characteristics to those of conventional accelerator-based neutron sources (e.g. short pulse durations, enabling novel applications like radiography). We present here results from an experiment aimed at performing a global characterization of the neutrons produced using the Titan laser at the Jupiter Laser Facility (Livermore, USA), where protons were accelerated from 23 $\mathrm {\mu }$m thick plastic targets and directed onto a LiF converter to produce neutrons. For this purpose, several diagnostics were used to measure these neutron emissions, such as CR-39, activation foils, time-of-flight detectors and direct measurement of $^7{\rm Be}$ residual activity in the LiF converters. The use of these different, independently operating diagnostics enables comparison of the various measurements performed to provide a robust characterization. These measurements led to a neutron yield of $2.0\times 10^{9}$ neutrons per shot with a modest angular dependence, close to that simulated.
Specifically designed microlattices are able to combine outstanding mechanical and physical properties and, thus, expand the actual limits of the material property space. However, post-yield softening induced by plastic buckling or crushing of individual ligaments limits performance under cyclic loading, which affects their energy absorption capabilities. Understanding deformation under repeated loading is key to further optimizing these high-strength materials. While until now mainly hollow metallic microlattices and multistable or tailored buckling structures have been analyzed, this study investigates deformation and failure of polymer and ceramic-polymer microlattices under cyclic loading to understand the (i) influence of the microarchitecture and (ii) influence of processing conditions on the energy absorption capability. Despite fracture of individual struts, the stretching-dominated microarchitectures possess a superior behavior especially for larger cycle numbers. In combination with a specific annealing treatment of the polymer material, high recoverability and energy dissipation can be achieved.
1 spoken or written words that have no meaning or make no sense: he was talking absolute nonsense.
• [as exclamation] used to show strong disagreement: ‘Nonsense! No one can do that.’
• [as modifier] denoting verse or other writing intended to be amusing by virtue of its absurd or whimsical language: nonsense poetry.
2 foolish or unacceptable behavior: put a stop to that nonsense, will you?
Introduction
Outrage arose when Representative Todd Akin of Missouri argued against making exceptions to the abortion restriction for rape victims on the grounds that due to a woman's physiology ‘legitimate rape’ was unlikely to result in pregnancy. Although thoroughly denounced, the claim that there is some feature of biology that prevents rapes from resulting in pregnancy has taken root in the political and popular imagination. This falsehood has proven so irrepressible that one reporter at Slate.com has written repeatedly about the ultimate source of this idea: a confabulated Nazi experiment. Discourse with these features– a ‘strange’ genealogy; bad reasoning; persistence despite, at best, specious proof; and exploitation for what are, to some minds, malicious purposes – has become increasingly common in political discourse, the press and even the arguments made by ordinary folk.
Such discourse is oft en criticized for its falsehood or its hurtfulness; these critiques – aimed at singular features of this discourse – tend to miss its pernicious potential.
In 1998, Daniel Loss and David DiVincenzo published a seminal paper describing how semiconductor quantum dots could be used to create spin qubits for quantum information processing [28]. They recognized that a single spin in a magnetic field forms a natural two-level system that can serve as a quantum bit. Moreover, owing to the weak magnetic moment of the electron, the spin is relatively well isolated from the environment leading to long coherence times. To confine single spins, Loss and DiVincenzo envisioned the quantum dot architecture shown in Fig. 15.1. A GaAs/AlGaAs heterostructure confines electrons to a two-dimensional electron gas (2DEG). Depletion gates are fabricated on top of the structure to provide a tunable confinement potential, trapping a single electron in each quantum dot. Neighboring quantum dots are tunnel coupled, with the coupling strength controlled by the electrostatic potential. The orientation of a single spin can be controlled by using electron spin resonance (ESR), while nearest-neighbor coupling is mediated by the depletion gate tunable exchange interaction.
It is fair to say that in 1998 many of the requirements of the Loss–DiVincenzo proposal had not been implemented, starting with the most basic necessity of a single electron lateral quantum dot [8]. The purpose of this chapter is to describe several experiments inspired by the Loss–DiVincenzo proposal. Many powerful experiments have been performed since 1998 and, given the space constraints here, we cannot give each experiment the attention it deserves.
Three dimensional visualization of ion channeling spectra was obtained by computer graphics in order to observe the crystalline quality and the strain state of thin films. Pure (100)Si and Si1-xGex (x=0.10, 0.18) layers, epitaxially grown on (100)Si substrates, were channeled along the <110> crystal axis with the 2 MeV He++ ion beam in a UHV target chamber. The data were interpolated using a standard bicubic tensor product B-spline surface with uniform knot sequences in x and y directions. With this modeling technique we have shown the orientation of the major planes in a diamond crystal and the angular displacement of the Ge signal in the SiGe epilayer relative to the Si substrate signal due to the presence of tetragonal distortion in the epilayer.
Recommend this
Email your librarian or administrator to recommend adding this to your organisation's collection.