Spectral multiplicity for powers of weakly mixing automorphisms

We study the behavior of maximal multiplicities $mm (R^n)$ for the powers of a weakly mixing automorphism $R$. For some special infinite set $A$ we show the existence of a weakly mixing rank-one automorphism $R$ such that $mm (R^n)=n$ and $mm(R^{n+1}) =1$ for all $n\in A$. Moreover, the cardinality $cardm(R^n)$ of the set of spectral multiplicities for $R^n$ is not bounded. We have $cardm(R^{n+1})=1$ and $cardm(R^n)=2^{m(n)}$, $m(n)\to\infty$, $n\in A$. We also construct another weakly mixing automorphism $R$ with the following properties: $mm(R^{n}) =n$ for $n=1,2,3,..., 2009, 2010$ but $mm(T^{2011}) =1$, all powers $(R^{n})$ have homogeneous spectrum, and the set of limit points of the sequence $\{\frac{mm (R^n)}{n} : n\in \N \}$ is infinite

Detection of organic materials by spectrometric radiography method

In this paper we report a spectrometric approach to dual-energy digital radiography that has been developed and applied to identify specific organic substances and discern small differences in their effective atomic number. An experimental setup has been designed, and a theoretical description proposed based on the experimental results obtained. The proposed method is based on application of special reference samples made of materials with different effective atomic number and thickness, parameters known to affect X-ray attenuation in the low-energy range. The results obtained can be used in the development of a new generation of multi-energy customs or medical X-ray scanners.Comment: 6 pages, 2 tables, 5 figures, will be presented at the Workshop on X-Ray Imaging, 22-24 October, 2008, Dresden, German

Photoconductivity of CdS-CdSe granular films: influence of microstructure

We study experimentally the photoconductivity of CdS-CdSe sintered granular films obtained by the screen printing method. We mostly focus on the dependences of photoconductivity on film's microstructure, which varies with changing heat-treatment conditions. The maximum photoconductivity is found for samples with compact packing of individual grains, which nevertheless are separated by gaps. Such a microstructure is typical for films heat-treated during an intermediate (optimal) time. In order to understand whether the dominant mechanism of charge transfer is identical with the one in monocrystals, we perform temperature measurements of photoresistance. Corresponding curves have the same peculiar nonmonotonic shape as in CdSe monocrystals, from which we conclude that the basic mechanism is also the same. It is suggested that the optimal heat-treatment time appears as a result of a competition between two mechanisms: improvement of film's connectivity and its oxidation. Photoresistance is also measured in vacuum and in helium atmosphere, which suppress oxygen and water absorption/chemisorption at intergrain boundaries. We demonstrate that this suppression increases photoconductivity, especially at high temperatures.Comment: 12 pages, 8 figures, final versio

EW-7197 prevents ulcerative colitis-associated fibrosis and inflammation

EW‐7197 is a transforming growth factor‐β type I receptor kinase inhibitor with potential anti‐inflammatory and antifibrotic properties. Here, we investigate the potential therapeutic effects of EW‐7197 in a murine model of ulcerative colitis. EW‐7197 attenuated the colitis disease activity index by improving rectal bleeding, body weight, and degree of stool consistency. EW‐7197 also reduced colorectal tissue damage and the colon histopathological score by reducing crypt loss, mucosal damage, and tissue inflammation. Moreover, EW‐7197 appeared to ameliorate the inflammatory and fibrotic responses by reducing oxidative stress, reducing submucosal edema and inflammatory cell infiltration, downregulating proinflammatory and pro‐fibrotic genes, and inhibiting excessive collagen deposition in inflamed and fibrotic ulcerative colitis tissues. These results suggest that EW‐7197 has potentially useful therapeutic properties against colitis, with clinically translational potential of inhibiting key pathological responses of inflammation and fibrosis in patients with colitis

Ultrabright room-temperature single-photon emission from nanodiamond nitrogen-vacancy centers with sub-nanosecond excited-state lifetime

Ultrafast emission rates obtained from quantum emitters coupled to plasmonic nanoantennas have recently opened fundamentally new possibilities in quantum information and sensing applications. Plasmonic nanoantennas greatly improve the brightness of quantum emitters by dramatically shortening their fluorescence lifetimes. Gap plasmonic nanocavities that support strongly confined modes are of particular interest for such applications. We demonstrate single-photon emission from nitrogen-vacancy (NV) centers in nanodiamonds coupled to nanosized gap plasmonic cavities with internal mode volumes about 10 000 times smaller than the cubic vacuum wavelength. The resulting structures features sub-nanosecond NV excited-state lifetimes and detected photon rates up to 50 million counts per second. Analysis of the fluorescence saturation allows the extraction of the multi-order excitation rate enhancement provided by the nanoantenna. Efficiency analysis shows that the NV center is producing up to 0.25 billion photons per second in the far-field

Preparing the upper gastrointestinal tract for an esophagogastroduodenoscopy to identify the source of acute bleeding

Esophagogastroduodenoscopy (EGDS) is the main way to diagnose bleeding from the upper gastrointestinal tract. Diagnostic accuracy of the study depends on the preparation. Aim of the study was to evaluate the preparation of the upper parts of the digestive tract in case of esophagogastroduodenal bleeding. Material and methods. The retrospective analysis of 2570 case histories was carried out. Gastric lavage through nasogastric tube was carried out in the main group (1299 patients). Preparation for the primary EGDS was not carried out in the control group (1271 patients). A comparison of the number of EGDS performed and the detection of the bleeding source in the control and the main groups as well as the period of investigation up to the detection of the bleeding source were performed. Results. EGDS without preparation of the upper gastrointestinal tract in case of acute bleeding and determination of the diagnosis is possible in 85,6 % of patients. Preparation of the upper gastrointestinal tract for EGDS prolongs the study period by 30–60 minutes, but allows establishing the diagnosis in 93.7 % of cases that is by 8.1 % more than without preparation