Packing Cones and Their Negatives in Space

Let C be a cone in R³ whose base B is a planar convex body in a horizontal plane π and whose tip is a point v ∉ π. Let C be a packing formed by translates of C and -C in R³. We exhibit an explicit constant c > 0 such that the density of any such C is smaller than 1 - c, answering a question of Wlodek Kuperberg.     

Time-Resolved Emission Spectra of Green Fluorescent Protein

The time-resolved emission spectra of wild-type green fluorescent protein (wtGFP) and the T203V GFP mutant have been recorded with picosecond time resolution, allowing the separate characterization of the two spectral components associated with the neutral and anionic forms of the GFP chromophore. Significantly, neither component shifts as a function of time. It is suggested that the absence of spectral shift is a result of highly restricted movement of the protein residues in the vicinity of the chromophore. The shapes of the separated spectra are discussed and their relative ratio analyzed in a steady-state analysis.     

35 J broadband femtosecond optical parametric chirped pulse amplification system

We report on what is believed to be the first large-aperture and high-energy optical parametric chirped pulse amplification system. The system, based on a three-stage amplifier, shows 25% pump-to-signal conversion efficiency and amplification of the full 70 nm width of the seed spectrum. Pulse compression to 84 fs achieved after amplification indicates a potential of 300 TW pulse power for 35 J amplified pulse energy.     

Optical parametric chirped-pulse amplification source suitable for seeding high-energy systems

A short-pulse source based on optical parametric chirped-pulse amplification (OPCPA) technology has been developed with properties that make it a suitable seed for a high-energy OPCPA system. This source generated a diffraction-limited pulse at 910 nm with a full bandwidth of > 165 nm and a spectrum having a transform-limited pulse duration of less than 15 fs. The technique has potential for generating bandwidths > 200 nm and pulse durations < 10 fs.     

Recent results on few-nucleon systems: Investigation from VBLHE-JINR

Recent results on the spin effects in deuteron inclusive breakup and deuteron-proton elastic scattering obtained at the Veksler and Baldin Laboratory of High Energies at JINR are reported. The experimental data have been obtained with the use of a high-energy polarized deuteron beam at the Synchrophasotron-Nuclotron Accelerator Complex. The covered energy range corresponds to the short internucleonic distances where the relativistic effects and non-nucleonic degrees of freedom can play a significant role.     

Status of the investigation of the spin structure of d, 3H, and 3He at VBLHE using polarized and unpolarized deuteron beam

The investigation of the spin structure of d, ³H, and ³He has been performed at the RIKEN acceleration research facility and VBLHE. Vector A _y and tensor A _yy , A _xx , A _xz analyzing powers for d → ³Hen and d → ³Hp are presented at 270 MeV. Themirror channels (³Hen and ³Hp) are comparedto each other in order to find possible manifestation of charge-symmetry breaking. The preliminary results on the polarization observables for d → ³Hp at 200MeV are also presented. The obtained data are compared with one-nucleon-exchange calculations.As a byproduct, d → pX and ¹²C → pX breakup reactions are investigated at 140, 200, and 270MeV. The experimental data on p elastic scattering were obtained at 270, 880, and 2000 MeV at the Nuclotron. The polarization of the deuteron beam was measured at 270 MeV at the internal target station. The preliminary data on the vector A _y and tensor A _yy , A _xx analyzing powers for the p elastic scattering at 880 MeV are presented. The calculations on A _y , A _yy , and A _xx analyzing powers for the p elastic scattering at 880 MeV were performed in the framework of the multiple-scattering model. The text was submitted by the authors in English.     

On the chromatic number of Kneser hypergraphs

We give a simple and elementary proof of Kríz's lower bound on the chromatic number of the Kneser -hypergraph of a set system .

     

Photon migration of Raman signal in bone as measured with spatially offset Raman spectroscopy

Spatially offset Raman spectroscopy (SORS) is currently being developed as an in vivo tool for bone disease detection, but to date, information about the interrogated volume as influenced by the light propagation and scattering characteristics of the bone matrix is still limited. This paper seeks to develop our general understanding of the sampling depths of SORS in bone specimens as a function of the applied spatial offset. Equine metacarpal bone was selected as a suitable specimen of compact cortical bone large enough to allow several thin slices (600 µm) to be cut from the dorsal surface. Photon migration at 830‐nm excitation was studied with five bone slices and a 380‐µm‐thin polytetrafluoroethylene (PTFE) slice placed consecutively between the layers. To optimize Raman signal recovery of the PTFE with increasing depth within the bone stack required a corresponding increase in spatial offset. For example, to sample effectively at 2.2‐mm depth within the bone required an optimal SORS offset of 7 mm. However, with a 7‐mm offset, the maximum accessible penetration depth from which the PTFE signal could be still recovered was 3.7 mm. These results provide essential basic information for developing SORS technology for medical diagnostics in general and optimizing sampling through bone tissue, permitting a better understanding of the relationship between the offset and depth of bone assessed, in particular. Potential applications include the detection of chemically specific markers for changes in bone matrix chemistry localized within the tissue and not present in healthy bone. © 2015 The Authors. Journal of Raman Spectroscopy published by John Wiley & Sons, Ltd.     

Subsurface analysis of painted sculptures and plasters using micrometre‐scale spatially offset Raman spectroscopy (micro‐SORS)

A recently developed variant of spatially offset Raman spectroscopy (SORS) for the non‐invasive analysis of thin painted layers, micro‐SORS, has been applied, for the first time, to real objects of Cultural Heritage – namely painted sculptures and plasters. Thin layers of paint originating from multiple restoration processes often applied over many centuries have been analysed non‐destructively using micro‐SORS to depths inaccessible to, or unresolvable into separate layers, by conventional confocal Raman microscopy. The concept has been demonstrated on several artistic artefacts of historical significance originating from Italy and dating from the medieval to the 18th century. The technique extends the depth applicability of Raman spectroscopy and with its inherently high chemical specificity that expands the portfolio of existing non‐destructive analytical tools in Cultural Heritage permitting to avoid cross‐sectional analysis often necessitated with this type of samples with conventional Raman microscopy. Currently, the method is non‐invasive only for artworks that can be placed under Raman microscope although there is a prospect for its use in a mobile system with largely removed restrictions on sample dimensions. © 2015 The Authors Journal of Raman Spectroscopy Published by John Wiley & Sons Ltd.