Thermal energy transformer

For use in combination with a heat engine, a thermal energy transformer is presented. It is comprised of a flux receiver having a first wall defining therein a radiation absorption cavity for converting solar flux to thermal energy, and a second wall defining an energy transfer wall for the heat engine. There is a heat pipe chamber interposed between the first and second walls having a working fluid disposed within the chamber and a wick lining the chamber for conducting the working fluid from the second wall to the first wall. Thermal energy is transferred from the radiation absorption cavity to the heat engine

The Vector Valued Quartile Operator

Certain vector-valued inequalities are shown to hold for a Walsh analog of the bilinear Hilbert transform. These extensions are phrased in terms of a recent notion of quartile type of a UMD (Unconditional Martingale Differences) Banach space X. Every known UMD Banach space has finite quartile type, and it was recently shown that the Walsh analog of Carleson's Theorem holds under a closely related assumption of finite tile type. For a Walsh model of the bilinear Hilbert transform however, the quartile type should be sufficiently close to that of a Hilbert space for our results to hold. A full set of inequalities is quantified in terms of quartile type.Comment: 32 pages, 5 figures, incorporates referee's report, to appear in Collect. Mat

Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth

In the present contribution we review basic mathematical results for three physical systems involving self-organising solid or liquid films at solid surfaces. The films may undergo a structuring process by dewetting, evaporation/condensation or epitaxial growth, respectively. We highlight similarities and differences of the three systems based on the observation that in certain limits all of them may be described using models of similar form, i.e., time evolution equations for the film thickness profile. Those equations represent gradient dynamics characterized by mobility functions and an underlying energy functional. Two basic steps of mathematical analysis are used to compare the different system. First, we discuss the linear stability of homogeneous steady states, i.e., flat films; and second the systematics of non-trivial steady states, i.e., drop/hole states for dewetting films and quantum dot states in epitaxial growth, respectively. Our aim is to illustrate that the underlying solution structure might be very complex as in the case of epitaxial growth but can be better understood when comparing to the much simpler results for the dewetting liquid film. We furthermore show that the numerical continuation techniques employed can shed some light on this structure in a more convenient way than time-stepping methods. Finally we discuss that the usage of the employed general formulation does not only relate seemingly not related physical systems mathematically, but does as well allow to discuss model extensions in a more unified way

Pointwise convergence of vector-valued Fourier series

We prove a vector-valued version of Carleson's theorem: Let Y=[X,H]_t be a complex interpolation space between a UMD space X and a Hilbert space H. For p\in(1,\infty) and f\in L^p(T;Y), the partial sums of the Fourier series of f converge to f pointwise almost everywhere. Apparently, all known examples of UMD spaces are of this intermediate form Y=[X,H]_t. In particular, we answer affirmatively a question of Rubio de Francia on the pointwise convergence of Fourier series of Schatten class valued functions.Comment: 26 page

Enhancement of laser-driven ion acceleration in non-periodic nanostructured targets

Using particle-in-cell simulations, we demonstrate an improvement of the target normal sheath acceleration (TNSA) of protons in non-periodically nanostructured targets with micron-scale thickness. Compared to standard flat foils, an increase in the proton cutoff energy by up to a factor of two is observed in foils coated with nanocones or perforated with nanoholes. The latter nano-perforated foils yield the highest enhancement, which we show to be robust over a broad range of foil thicknesses and hole diameters. The improvement of TNSA performance results from more efficient hot-electron generation, caused by a more complex laser-electron interaction geometry and increased effective interaction area and duration. We show that TNSA is optimized for a nanohole distribution of relatively low areal density and that is not required to be periodic, thus relaxing the manufacturing constraints.Comment: 11 pages, 8 figure

"Drinking in the Dark" (DID): a simple mouse model of binge-like alcohol intake

One of the greatest challenges that scientists face when studying the neurobiology and/or genetics of alcohol (ethanol) consumption is that most preclinical animal models do not voluntarily consume enough ethanol to achieve pharmacologically meaningful blood ethanol concentrations (BECs). Recent rodent models have been developed that promote binge-like levels of ethanol consumption associated with high BECs (i.e., ≥100 mg/dl). This unit describes procedures for an animal model of binge-like ethanol drinking which has come to be called "drinking in the dark" (DID). The "basic" variation of DID involves replacing the water bottle with a bottle containing 20% ethanol for 2 to 4 hr, beginning 3 hr into the dark cycle, on cages of singly-housed C57BL/6J mice. Using this procedure, mice typically consume enough ethanol to achieve BECs >100 mg/dl and to exhibit behavioral evidence of intoxication. An alternative two-bottle (ethanol and water) procedure is also described

Influence of strain on magnetization and magnetoelectric effect in La0.7A0.3MnO3 / PMN-PT(001) (A = Sr; Ca)

We investigate the influence of a well-defined reversible biaxial strain <=0.12 % on the magnetization (M) of epitaxial ferromagnetic manganite films. M has been recorded depending on temperature, strain and magnetic field in 20 - 50 nm thick films. This is accomplished by reversibly compressing the isotropic in-plane lattice parameter of the rhombohedral piezoelectric 0.72PMN-0.28PT (001) substrates by application of an electric field E <= 12 kV cm-1. The magnitude of the total variable in-plane strain has been derived. Strain-induced shifts of the ferromagnetic Curie temperature (Tc) of up to 19 K were found in La0.7Sr0.3MnO3 (LSMO) and La0.7Ca0.3MnO3 films and are quantitatively analysed for LSMO within a cubic model. The observed large magnetoelectric coupling coefficient alpha=mu0 dM/dE <= 6 10-8 s m-1 at ambient temperature results from the strain-induced M change in the magnetic-film-ferroelectric-substrate system. It corresponds to an enhancement of mu0 DeltaM <= 19 mT upon biaxial compression of 0.1 %. The extraordinary large alpha originates from the combination of three crucial properties: (i) the strong strain dependence of M in the ferromagnetic manganites, (ii) large piezo-strain of the PMN-PT substrates and (iii) effective elastic coupling at the film-substrate interface.Comment: 15 pages, 6 figures, 1 tabl

Dewetting of thin films on heterogeneous substrates: Pinning vs. coarsening

We study a model for a thin liquid film dewetting from a periodic heterogeneous substrate (template). The amplitude and periodicity of a striped template heterogeneity necessary to obtain a stable periodic stripe pattern, i.e. pinning, are computed. This requires a stabilization of the longitudinal and transversal modes driving the typical coarsening dynamics during dewetting of a thin film on a homogeneous substrate. If the heterogeneity has a larger spatial period than the critical dewetting mode, weak heterogeneities are sufficient for pinning. A large region of coexistence between coarsening dynamics and pinning is found.Comment: 4 pages, 4 figure

Acute clinical deterioration and consumer escalation in the hospital setting: a literature review

BACKGROUND: Consumer escalation systems that allow patients and/or their family/carers to escalate concerns about clinical deterioration have been proposed as a way of enhancing patient safety. However, evidence to guide implementation or to support system effectiveness remains unclear. AIM: To critically evaluate the current evidence surrounding consumer escalation within the context of clinical deterioration to identify the strengths, weaknesses and gaps in existing knowledge, essential themes, and directions for further investigation. METHOD: Database searches were conducted within Cumulative Index of Nursing and Allied Health Literature, PubMed, and the Cochrane Library for articles directly relating to consumer escalation systems published, in English, within the previous 10 year-period. Titles and abstracts were screened and relevant full-text articles included. Content was examined to identify breadth of knowledge, essential themes, and the effectiveness of current systems. RESULTS: 27 articles, containing a mixture of both quantitative and qualitative findings, were identified. Within the context of limitations in the overall depth and quality of current evidence, four key areas (relating to consumer understanding and awareness of clinical deterioration, confidence and ability to escalate concerns, education, and staff attitudes) were identified as potentially critical to the foundation, functioning, and success of consumer escalation systems. Consumer escalation processes may contribute positive effects beyond mortality rates; however, an agreed method of assessing effectiveness remains undetermined. CONCLUSIONS: The ability of consumer escalation processes to achieve their underlying goals is still to be adequately assessed. Further research is required to inform how to best implement, support and optimise consumer escalation systems.Lisa Thiele, Arthas Flabouris, Campbell Thompso

Interplay between magnetic anisotropy and interlayer coupling in nanosecond magnetization reversal of spin-valve trilayers

The influence of magnetic anisotropy on nanosecond magnetization reversal in coupled FeNi/Cu/Co trilayers was studied using a photoelectron emission microscope combined with x-ray magnetic circular dicroism. In quasi-isotropic samples the reversal of the soft FeNi layer is determined by domain wall pinning that leads to the formation of small and irregular domains. In samples with uniaxial magnetic anisotropy, the domains are larger and the influence of local interlayer coupling dominates the domain structure and the reversal of the FeNi layer