Reactor for simulation and acceleration of solar ultraviolet damage

An environmental test chamber providing acceleration of UV radiation and precise temperature control (+ or -)1 C was designed, constructed and tested. This chamber allows acceleration of solar ultraviolet up to 30 suns while maintaining temperature of the absorbing surface at 30 C - 60 C. This test chamber utilizes a filtered medium pressure mercury arc as the source of radiation, and a combination of selenium radiometer and silicon radiometer to monitor solar ultraviolet (295-340 nm) and total radiant power output, respectively. Details of design and construction and operational procedures are presented along with typical test data

Pyrheliometric comparisons at the JPL Table Mountain Facility

Calibration and comparative measurements of pyrheliometric instruments using natural sunligh

The physical origin of the Fresnel drag of light by a moving dielectric medium

We present a new derivation of the Fresnel-Fizeau formula for the drag of light by a moving medium using a simple perturbation approach. We focus particulary on the physical origin of the phenomenon and we show that it is very similar to the Doppler-Fizeau effect. We prove that this effect is, in its essential part, independent of the theory of relativity. The possibility of applications in other domains of physics is considered.Comment: accepted for publication in EPJB (the European Journal of Physics B

Study of chirally motivated low-energy K−K^- optical potentials

The $K^-$ optical potential in the nuclear medium is evaluated self consistently from a free-space $K^-N$ $t$ matrix constructed within a coupled-channel chiral approach to the low-energy $\bar K N$ data. The chiral-model parameters are fitted to a select subset of the low-energy data {\it plus} the $K^-$ atomic data throughout the periodic table. The resulting attractive $K^-$ optical potentials are relatively `shallow', with central depth of the real part about 55 MeV, for a fairly reasonable reproduction of the atomic data with $\chi^2 / N \approx 2.2$. Relatively `deep' attractive potentials of depth about 180 MeV, which result in other phenomenological approaches with $\chi^2 / N \approx 1.5$, are ruled out within chirally motivated models. Different physical data input is required to distinguish between shallow and deep $K^-$ optical potentials. The ($K^{-}_{\rm stop},\pi$) reaction could provide such a test, with exclusive rates differing by over a factor of three for the two classes of potentials. Finally, forward ($K^-,p$) differential cross sections for the production of relatively narrow deeply bound $K^-$ {\it nuclear} states are evaluated for deep $K^-$ optical potentials, yielding values considerably lower than those estimated before.Comment: 22 pages, 3 figures, minor revisions, Nucl. Phys. A in pres

Phi meson production in near threshold proton-nucleus collisions

The cross section for production of Phi mesons in proton-nucleus reactions is calculated as a function of the target mass. The decay width of the Phi meson is affected by the change of the masses of the Phi, K+ and K- mesons in the medium. A strong attractive K- potential leads to a measurable change of the behavior of the cross section as a function of of the target mass. Comparison between the kaon and electron decay modes are made.Comment: 4 pages, 1figure, new figure, new reference

An investigation of the degradation of Fluorinated Ethylene Propylene (FEP) copolymer thermal blanketing materials aboard LDEF in the laboratory

Samples of fluorinated ethylene propylene copolymer thermal blanketing material, recovered from the Long Duration Exposure Facility (LDEF), were investigated to determine the nature and the extent of degradation due to exposure to the low-Earth-orbit environment. Samples recovered from the ram-facing direction of LDEF, which received vacuum-ultraviolet (VUV) radiation and atomic-oxygen impingement, and samples from the trailing edge, which received almost exclusively VUV exposure, were investigated by scanning electron microscopy and atomic force microscopy. The most significant result of this investigation was found on samples that received only VUV exposure. These samples possessed a hard, embrittled surface layer that was absent from the atomic-oxygen exposed sample and from unexposed control samples. This surface layer is believed to be responsible for the 'synergistic' effect between VUV and atomic oxygen. Overall, the investigation revealed dramatically different morphologies for the two samples. The sample receiving both atomic-oxygen and VUV exposure was deeply eroded and had a characteristic 'rolling' surface morphology, while the sample that received only VUV exposure showed mild erosion and a surface morphology characterized by sharp high-frequency peaks. The morphologies observed in the LDEF samples, including the embrittled surface layer, were successfully duplicated in the laboratory

Time dependence of Bragg forward scattering and self-seeding of hard x-ray free-electron lasers

Free-electron lasers (FELs) can now generate temporally short, high power x-ray pulses of unprecedented brightness, even though their longitudinal coherence is relatively poor. The longitudinal coherence can be potentially improved by employing narrow bandwidth x-ray crystal optics, in which case one must also understand how the crystal affects the field profile in time and space. We frame the dynamical theory of x-ray diffraction as a set of coupled waves in order to derive analytic expressions for the spatiotemporal response of Bragg scattering from temporally short incident pulses. We compute the profiles of both the reflected and forward scattered x-ray pulses, showing that the time delay of the wave $\tau$ is linked to its transverse spatial shift $\Delta x$ through the simple relationship $\Delta x = c\tau \cot\theta$, where $\theta$ is the grazing angle of incidence to the diffracting planes. Finally, we apply our findings to obtain an analytic description of Bragg forward scattering relevant to monochromatically seed hard x-ray FELs.Comment: 11 pages, 6 figure

Heavy Quark Diffusion and Lattice Correlators

We study charmonia correlators at finite temperature. We analyze to what extent heavy quarkonia correlators are sensitive to the effect of heavy quark transport and whether it is possible to constrain the heavy quark diffusion constant by lattice calculations. Preliminary lattice calculations of quarkonia correlators performed on anisotropic lattices show that they are sensitive to the effect of heavy quark transport, but much detailed calculations are required to constrain the value of the heavy quark diffusion constant.Comment: Based on talks presented on Lattice 2005, Extreme QCD 2005 and Quark Matter 2005, 5 pages, 4 Figure

Decoupling Simulated Annealing From Massive Multiplayer Online Role-Playing Games in RAID

End-users agree that compact technology are an interesting new topic in the field of electri- cal engineering, and physicists concur. In fact, few futurists would disagree with the deploy- ment of Byzantine fault tolerance, demonstrates the structured importance of cryptography. We construct a novel algorithm for the simulation of write-ahead logging (JDL), validating that Byzantine fault tolerance can be made peer-to- peer, classical, and stable. It is often an important mission but is supported by previous work in the field

Dynamic monitoring of single cell lysis in an impedance-based microfluidic device.

A microfluidic device that is capable of trapping and sensing dynamic variations in the electrical properties of individual cells is demonstrated. The device is applied to the real-time recording of impedance measurements of mouse embryonic stem cells (mESCs) during the process of membrane lysis, with the resulting changes in the electrical properties of cells during this process being quantitatively tracked over time. It is observed that the impedance magnitude decreases dramatically after cell membrane lysis. A significant shift in the phase spectrum is also observed during the time course of this process. By fitting experimental data to physical models, the electrical parameters of cells can be extracted and parameter variations quantified during the process. In the cell lysis experiments, the equivalent conductivity of the cell membrane is found to increase significantly due to pore formation in the membrane during lysis. An increase in the specific capacitance of the membrane is also observed. On the other hand, the conductivity of the cytoplasm is observed to decrease, which may be explained the fact that excess water enters the cell through the gradual permeabilization of the membrane during lysis. Cells can be trapped in the device for periods up to several days, and their electrical response can be monitored by real-time impedance measurements in a label-free and non-invasive manner. Furthermore, due to the highly efficient single cell trapping capacity of the device, a number of cells can be trapped and held in separate wells for concurrent parallel experiments, allowing for the possibility of stepped parametric experiments and studying cell heterogeneity by combining measurements across the array.Biotechnology and Biological Sciences Research Council (Grant ID: BB/K013726/1)This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s10544-016-0081-