97 research outputs found
Review of the ELI-NP-GBS low level rf and synchronization systems
The Gamma Beam System (GBS) of ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module, for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described
Atomistic defect states as quantum emitters in monolayer MoS
Quantum light sources in solid-state systems are of major interest as a basic
ingredient for integrated quantum device technologies. The ability to tailor
quantum emission through deterministic defect engineering is of growing
importance for realizing scalable quantum architectures. However, a major
difficulty is that defects need to be positioned site-selectively within the
solid. Here, we overcome this challenge by controllably irradiating
single-layer MoS using a sub-nm focused helium ion beam to
deterministically create defects. Subsequent encapsulation of the ion bombarded
MoS flake with high-quality hBN reveals spectrally narrow emission lines
that produce photons at optical wavelengths in an energy window of one to two
hundred meV below the neutral 2D exciton of MoS. Based on ab-initio
calculations we interpret these emission lines as stemming from the
recombination of highly localized electron-hole complexes at defect states
generated by the helium ion bombardment. Our approach to deterministically
write optically active defect states in a single transition metal
dichalcogenide layer provides a platform for realizing exotic many-body
systems, including coupled single-photon sources and exotic Hubbard systems.Comment: Main: 9 pages, 3 figures + SI: 19 pages, 10 figure
Impurity and strain effects on the magnetotransport of La1.85Sr0.15Cu(1-y)Zn(y)O4 films
The influence of zinc doping and strain related effects on the normal state
transport properties(the resistivity, the Hall angle and the orbital magneto-
resistance(OMR) is studied in a series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with
values of y between 0 and 0.12 and various degrees of strain induced by the
mismatch between the films and the substrate. The zinc doping affects only the
constant term in the temperature dependence of cotangent theta but the strain
affects both the slope and the constant term, while their ratio remains
constant.OMR is decreased by zinc doping but is unaffected by strain. The ratio
delta rho/(rho*tan^2 theta) is T-independent but decreases with impurity
doping. These results put strong constraints on theories of the normal state of
high- temperature superconductors
Finite element simulation of three-dimensional free-surface flow problems
An adaptive finite element algorithm is described for the stable solution of three-dimensional free-surface-flow problems based primarily on the use of node movement. The algorithm also includes a discrete remeshing procedure which enhances its accuracy and robustness. The spatial discretisation allows an isoparametric piecewise-quadratic approximation of the domain geometry for accurate resolution of the curved free surface.
The technique is illustrated through an implementation for surface-tension-dominated viscous flows modelled in terms of the Stokes equations with suitable boundary conditions on the deforming free surface. Two three-dimensional test problems are used to demonstrate the performance of the method: a liquid bridge problem and the formation of a fluid droplet
Linear optical absorption spectra of mesoscopic structures in intense THz fields: free particle properties
We theoretically study the effect of THz radiation on the linear optical
absorption spectra of semiconductor structures. A general theoretical
framework, based on non-equilibrium Green functions, is formulated, and applied
to the calculation of linear optical absorption spectrum for several
non-equilibrium mesoscopic structures. We show that a blue-shift occurs and
sidebands appear in bulk-like structures, i.e., the dynamical Franz-Keldysh
effect [A.-P. Jauho and K. Johnsen, Phys. Rev. Lett. 76, 4576 (1996)]. An
analytic calculation leads to the prediction that in the case of superlattices
distinct stable steps appear in the absorption spectrum when conditions for
dynamical localization are met.Comment: 13 Pages, RevTex using epsf to include 8 ps figures. Submitted to
Phys. Rev. B (3 April 97
Magnetotransport in the Normal State of La1.85Sr0.15Cu(1-y)Zn(y)O4 Films
We have studied the magnetotransport properties in the normal state for a
series of La1.85Sr0.15Cu(1-y)Zn(y)O4 films with values of y, between 0 and
0.12. A variable degree of compressive or tensile strain results from the
lattice mismatch between the substrate and the film, and affects the transport
properties differently from the influence of the zinc impurities. In
particular, the orbital magnetoresistance (OMR) varies with y but is
strain-independent. The relations for the resistivity and the Hall angle and
the proportionality between the OMR and tan^2 theta are followed about 70 K. We
have been able to separate the strain and impurity effects by rewriting the
above relations, where each term is strain-independent and depends on y only.
We also find that changes in the lattice constants give rise to closely the
same fractional changes in other terms of the equation.The OMR is more strongly
supressed by the addition of impurities than tan^2 theta. We conclude that the
relaxation ratethat governs Hall effect is not the same as for the
magnetoresistance. We also suggest a correspondence between the transport
properties and the opening of the pseudogap at a temperature which changes when
the La-sr ratio changes, but does not change with the addition of the zinc
impurities
Photocytotoxicity of mTHPC (Temoporfin) Loaded Polymeric Micelles Mediated by Lipase Catalyzed Degradation
Purpose. To study the in vitro photocytotoxicity and cellular uptake of biodegradable polymeric micelles loaded with the photosensitizer mTHPC, including the effect of lipase-catalyzed micelle degradation. Methods. Micelles of mPEG750-b-oligo(ɛ-caprolactone)5 (mPEG750-b-OCL5) with a hydroxyl (OH), benzoyl (Bz) or naphthoyl (Np) end group were formed and loaded with mTHPC by the film hydration method. The cellular uptake of the loaded micelles, and their photocytotoxicity on human neck squamous carcinoma cells in the absence and presence of lipase were compared with free and liposomal mTHPC (Fospeg ®). Results. Micelles composed of mPEG750-b-OCL5 with benzoyl and naphtoyl end groups had the highest loading capacity up to 30 % (w/w), likely due to π–π interactions between the aromatic end group and the photosensitizer. MTHPC-loaded benzoylated micelles (0.5 mg/mL polymer) did not display photocytotoxicity or any mTHPC-uptake by the cells, in contrast to free and liposomal mTHPC. After dilution of the micelles below the critical aggregation concentration (CAC), or after micelle degradation by lipase, photocytotoxicity and cellular uptake of mTHPC were restored. Conclusion. The high loading capacity of the micelles, the high stability of mTHPC-loaded micelles above the CAC, and the lipase-induced release of the photosensitizer makes these micelles very promising carriers for photodynamic therapy in vivo. KEY WORDS: drug release; enzymatic degradation; meta-tetra(hydroxyphenyl)chlorin (mTHPC); photodynamic therapy (PDT); polymeric micelles
Strategies to reduce medication errors with reference to older adults
Background  In Australia, around 59% of the general population uses prescription medication with this number increasing to about 86% in those aged 65 and over and 83% of the population over 85 using two or more medications simultaneously. A recent report suggests that between 2% and 3% of all hospital admissions in Australia may be medication related with older Australians at higher risk because of higher levels of medicine intake and increased likelihood of being admitted to hospital. The most common medication errors encountered in hospitals in Australia are prescription/medication ordering errors, dispensing, administration and medication recording errors. Contributing factors to these errors have largely not been reported in the hospital environment. In the community, inappropriate drugs, prescribing errors, administration errors, and inappropriate dose errors are most common. Objectives  To present the best available evidence for strategies to prevent or reduce the incidence of medication errors associated with the prescribing, dispensing and administration of medicines in the older persons in the acute, subacute and residential care settings, with specific attention to persons aged 65 years and over. Search strategy  Bibliographic databases PubMed, Embase, Current contents, The Cochrane Library and others were searched from 1986 to present along with existing health technology websites. The reference lists of included studies and reviews were searched for any additional literature. Selection criteria  Systematic reviews, randomised controlled trials and other research methods such as non-randomised controlled trials, longitudinal studies, cohort or case-control studies, or descriptive studies that evaluate strategies to identify and manage medication incidents. Those people who are involved in the prescribing, dispensing or administering of medication to the older persons (aged 65 years and older) in the acute, subacute or residential care settings were included. Where these studies were limited, evidence available on the general patient population was used. Data collection and analysis  Study design and quality were tabulated and relative risks, odds ratios, mean differences and associated 95% confidence intervals were calculated from individual comparative studies containing count data where possible. All other data were presented in a narrative summary. Results  Strategies that have some evidence for reducing medication incidents are: •  computerised physician ordering entry systems combined with clinical decision support systems; •  individual medication supply systems when compared with other dispensing systems such as ward stock approaches; •  use of clinical pharmacists in the inpatient setting; •  checking of medication orders by two nurses before dispensing medication; •  a Medication Administration Review and Safety committee; and •  providing bedside glucose monitors and educating nurses on importance of timely insulin administration. In general, the evidence for the effectiveness of intervention strategies to reduce the incidence of medication errors is weak and high-quality controlled trials are needed in all areas of medication prescription and delivery
International differences in employee silence motives: Scale validation, prevalence, and relationships with culture characteristics across 33 Countries
Employee silence, the withholding of work-related ideas, questions, or concerns from someone who could effect change, has been proposed to hamper individual and collective learning as well as the detection of errors and unethical behaviors in many areas of the world. To facilitate cross-cultural research, we validated an instrument measuring four employee silence motives (i.e., silence based on fear, resignation, prosocial, and selfish motives) in 21 languages. Across 33 countries (N = 8,222) representing diverse cultural clusters, the instrument shows good psychometric properties (i.e., internal reliabilities, factor structure, measurement invariance). Results further revealed similarities and differences in the prevalence of silence motives between countries, but did not necessarily support cultural stereotypes. To explore the role of culture for silence, we examined relationships of silence
motives with the societal practices cultural dimensions from the GLOBE Program. We found relationships between silence motives and power distance, institutional collectivism, and uncertainty avoidance. Overall, the findings suggest that relationships between silence and cultural dimensions are more complex than commonly assumed. We discuss the explanatory power of nations as (cultural) units of analysis, our social scientific approach, the predictive value of cultural dimensions, and opportunities to extend silence research geographically, methodologically, and conceptuallyinfo:eu-repo/semantics/publishedVersio
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