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Protective wrapping of off-the-shelf components
System designers using off-the-shelf components (OTSCs), whose internals they cannot change, often use add-on âwrappersâ to adapt the OTSCsâ behaviour as required. In most cases, wrappers are used to change âfunctionalâ properties of the components they wrap. In this paper we discuss instead protective wrapping, the use of wrappers to improve the dependability â i.e., ânon-functionalâ properties like availability, reliability, security, and/or safety â of a component and thus of a system. Wrappers can improve dependability by adding fault tolerance, e.g. graceful degradation, or error recovery mechanisms. We discuss the rational specification of such protective wrappers in view of system dependability requirements, and highlight some of the design trade-offs and uncertainties that affect system design with OTSCs and wrappers, and that differentiate it from other forms of fault-tolerant design
Digital diplomacy in GCC countries: strategic communication of Western embassies on Twitter
Drawing upon online communication research, this study identifies six effective communication strategies for social media-based diplomacy on Twitter: interactive, personalized, positive, relevant, and transparent communication among a broad network of stakeholders. By using an extensive mix-method design (i.e., combining a manual content and automated network analyses, N = 4438 tweets), this research examines to what extent these communication strategies are adopted on Twitter by Western embassies active in countries from the Gulf Cooperation Council. We found that embassies are not utilizing social media to its full potential. Although embassies are transparent, use positive sentiment in their online communication and post relevant information to their stakeholders, they hardly engage in direct interactive and personal communication, and only reach out to a limited group of stakeholders. We recommend embassies to put more emphasis on two-way interactive communication with a vast variety of stakeholders
Optimization of 68Ga production at an 18 MeV medical cyclotron with solid targets by means of cross-section measurement of  66Ga, 67Ga and 68Ga.
The future development of personalized nuclear medicine relies on the availability of novel medical radionuclides. In particular, radiometals are attracting considerable interest since they can be used to label both proteins and peptides. Among them, the ÎČ+-emitter 68Ga is widely used in nuclear medicine for positron emission tomography (PET). It is used in theranostics as the diagnostic partner of the therapeutic ÎČ--emitters 177Lu and 90Y for the treatment of a wide range of diseases, including prostate cancer. Currently, 68Ga is usually obtained via 68Ge/68Ga generators. However, their availability, high price and limited produced radioactivity per elution are a major barrier for a wider use of the 68Ga-based diagnostic radiotracers. A promising solution is the production of 68Ga by means of proton irradiation of enriched 68Zn liquid or solid targets. Along this line, a research program is ongoing at the Bern medical cyclotron, equipped with a solid target station. In this paper, we report on the measurements of 68Ga, 67Ga and 66Ga production cross-sections using natural Zn and enriched 68Zn material, which served as the basis to perform optimized 68Ga production tests with enriched 68Zn solid targets
Light emission and spin-polarised hole injection in InAs/GaAs quantum dot heterostructures with Schottky contact
EPL draftWe demonstrate the feasibility to obtain electroluminescence (EL), up to room temperature, from InGaAs self-assembled quantum dots (QDs) included in a forward-biased Schottky
diode. Moreover, using a ferromagnet (FM) as the contact layer, sizable circular polarization of
the EL emission in the presence of an external magnetic eld is obtained. A resonant behav-
ior of the degree of circular polarization (P) as a function of applied voltage (V ), for a given
value of magnetic eld, is observed. We explain our ndings using a model including tunneling
of (spin-polarised) holes through the metal-semiconductor interface, transport in the near surface
region of the heterostructure and out-of-equilibrium statistics of the injected carriers occupying
the available states in the QD heterostructure. In particular, the resonant P(V ) dependence is
related to the splitting of the qusi-Fermi level for two spin orientations in the FM.FCT, Portugal (project
POCI/FIS/58524/2004), the RFBR, Russia (grant 10-02-
00501), MEC (grants MAT2008-01555, QOIT-CSD2006-
00019) and CAM (S-2009/ESP-1503) (Spain)
Experimental Verification of the Chemical Sensitivity of Two-Site Double Core-Hole States Formed by an X-ray FEL
We have performed X-ray two-photon photoelectron spectroscopy (XTPPS) using
the Linac Coherent Light Source (LCLS) X-ray free-electron laser (FEL) in order
to study double core-hole (DCH) states of CO2, N2O and N2. The experiment
verifies the theory behind the chemical sensitivity of two-site (ts) DCH states
by comparing a set of small molecules with respect to the energy shift of the
tsDCH state and by extracting the relevant parameters from this shift.Comment: 11 pages, 2 figure
de Sitter limit of inflation and nonlinear perturbation theory
We study the fourth order action of the comoving curvature perturbation in an
inflationary universe in order to understand more systematically the de Sitter
limit in nonlinear cosmological perturbation theory. We derive the action of
the curvature perturbation to fourth order in the comoving gauge, and show that
it vanishes sufficiently fast in the de Sitter limit. By studying the de Sitter
limit, we then extrapolate to the n'th order action of the comoving curvature
perturbation and discuss the slow-roll order of the n-point correlation
function.Comment: 14 pages, 1 figure; typos corrected and discussion of tensor modes
adde
A Simple Operator Check of the Effective Fermion Mode Function during Inflation
We present a relatively simple operator formalism which reproduces the
leading infrared logarithm of the one loop quantum gravitational correction to
the fermion mode function on a locally de Sitter background. This rule may
serve as the basis for an eventual stochastic formulation of quantum gravity
during inflation. Such a formalism would not only effect a vast simplification
in obtaining the leading powers of at fixed loop orders, it would also
permit us to sum the series of leading logarithms. A potentially important
point is that our rule does not seem to be consistent with any simple infrared
truncation of the fields. Our analysis also highlights the importance of spin
as a gravitational interaction that persists even when kinetic energy has
redshifted to zero.Comment: 39 pages, no figuire.(1) New version has clarified the ultimate
motivation by adding sentences to the abstract and to the penultimate
paragraph of the introduction. (2) By combining a number of references and
equations we have managed to reduce the length by 2 page
Quantum back-reaction of the superpartners in a large-N supersymmetric hybrid model
We study the supersymmetric hybrid model near and after the end of inflation.
As usual, we reduce the model to a purely scalar hybrid model on the level of
the classical fields. But on the level of quantum fluctuations and their
backreaction we take into account all superpartners of the waterfall field in a
large-N approximation. The evolution after slow roll displays two phases with a
different characteristic behaviour of the classical and fluctuation fields. We
find that the fluctuations of the pseudoscalar superpartner are of particular
importance in the late time phase. The motion of the waterfall field towards
its classical expectation value is found to be very slow and suggests a rather
flat potential and a stochastic force.Comment: 37 pages 19 figure
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