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21.
Valais I.G. Michail C.M. David S.L. Konstantinidis A. Cavouras D.A. Kandarakis I.S. Panayiotakis G.S. 《IEEE transactions on nuclear science》2008,55(2):785-789
LYSO:Ce and LuYAP:Ce are single crystal non-hygroscopic scintillators of high density, high light yield and short decay time, which have been successfully used in small animal PET imagers. In the present study, the luminescence emission properties of (Lu0.9, Y0.1)2SiO5:Ce (LYSO:Ce) and (Lu0.7, Y0.3)AIO3:Ce (LuYAP:Ce) crystals were investigated for use in X-ray medical imaging. Both crystals had dimensions of 2 times 2 times 8 mm3, with all surfaces polished. Evaluation was performed by determining the X-ray luminescence efficiency (XLE) (emitted light energy flux over incident X-ray energy flux) and the detector optical gain (DOG) (emitted light photons per incident x-ray photon) in a wide range of X-ray energies employed in mammography (22-49 kVp) and in general X-ray imaging (50-140 kVp). Measurements were performed using an experimental set-up based on a photomultiplier coupled to an integration sphere. The emission spectrum under X-ray excitation was measured using an optical grating monochromator to determine the spectral compatibility to various optical photon detectors incorporated in medical imaging detectors. Optical characteristics such as transmission and absorption spectra were investigated in addition to the scintillation properties. The light emission performance of the two scintillation materials studied was found adequately high for X-ray imaging. 相似文献
22.
Michail I. Gladyshev Nadezhda N. Sushchik Galina A. Gubanenko Sevilia M. Demirchieva Galina S. Kalachova 《Food chemistry》2007,101(4):1694-1700
Frozen samples of common fish species, sea trout (Salmo trutta), from Norway and Siberia, herring (Clupea harengus pallasi), rock sole (Lepidopsetta bilineata) and cod (Gadus morhua maris-albi), collected from a wholesale market in Krasnoyarsk city (Siberia, Russia) were analyzed. Special attention was paid to long-chain essential polyunsaturated fatty acids: eicosapentaenoic, 20:5ω3 (EPA) and docosahexaenoic, 22:6ω3 (DHA). Heat-treatment (cooking and frying) did not in general significantly decrease the contents of EPA and DHA compared to raw fish species, except for a modest reduction in Norwegian trout during frying. Boiled trout appeared to be a more valuable fish dish for obtaining the officially recommended appropriate daily intake of EPA + DHA for humans. Herring and sole had intermediate values, while boiled cod had a comparatively low value. 相似文献
23.
Michail Vlachos Aris Anagnostopoulos Olivier Verscheure Philip S. Yu 《The VLDB Journal The International Journal on Very Large Data Bases》2009,18(1):77-98
This paper answers the following question; given a multiplicity of evolving 1-way conversations, can a machine or an algorithm discern the conversational pairs in an online fashion, without understanding the content of the communications? Our analysis indicates that this is possible, and can be achieved just by exploiting the temporal dynamics inherent in a conversation. We also show that our findings are applicable for anonymous and encrypted conversations over VoIP networks. We achieve this by exploiting the aperiodic inter-departure time of VoIP packets, hence trivializing each VoIP stream into a binary time-series, indicating the voice activity of each stream. We propose effective techniques that progressively pair conversing parties with high accuracy and in a limited amount of time. Our findings are verified empirically on a dataset consisting of 1,000 conversations. We obtain very high pairing accuracy that reaches 97% after 5 min of voice conversations. Using a modeling approach we also demonstrate analytically that our result can be extended over an unlimited number of conversations. 相似文献
24.
Artem A. Barabanov Nina V. Semikolenova Michail A. Matsko Ljudmila G. Echevskaya Vladimir A. Zakharov 《Polymer》2010,51(15):3354-1654
The effects of polymerization time and temperature on the molecular weight and molecular weight distribution of polyethylene, produced over homogeneous catalyst bis[N-(3-tert-butyl salicylidene)anilinato]zirconium(IV) dichloride tBu-L2ZrCl2/MAO have been studied. The data on the number of active centers (CP) and propagation rate constants (kP) at different polymerization time have been obtained as well. It was found that at a short polymerization time two types of active centers, producing low molecular weight PE (Mw = (4-10) × 103 g mol−1) are formed. The number of these centers was estimated to be 11% of total zirconium complex and their reactivity is very high (the kP value was found to be 54 × 103 L mol−1 s−1 at 35 °C). High initial activity of the catalyst fell with the increase in polymerization time, whereas the polydispersity values of the resulting PE increase due to formation of new centers, producing high molecular weight PE (Mw = (30-1300) × 103 g mol−1). It was found that the decrease in activity is caused by reducing the initial active centers number and lower reactivity of the new-formed centers (kP = 17 × 103 L mol−1 s−1). 相似文献
25.
Dina V. Dudina Igor S. Batraev Vladimir Yu. Ulianitsky Natalia V. Bulina Michail A. Korchagin Ivan A. Bataev Alberto Moreira Jorge Jr. 《Journal of Thermal Spray Technology》2014,23(7):1116-1123
In thermally sprayed coatings, nano-sized features of the microstructure may be either inherited from the nanostructured agglomerates of the feedstock powder or form as a result of rapid cooling of molten particles upon deposition. Applying a process of the computer-controlled detonation spraying (CCDS) to Ti3SiC2-Cu composite powders produced by high-energy mechanical milling, we show that both routes are possible depending on the spraying conditions. When the nanostructure of the Ti3SiC2-Cu coating is inherited from the feedstock powder—under very mild conditions of detonation spraying, which exclude melting, so is the phase composition of the coating. In higher-temperature conditions of spraying, a significant fraction of the copper matrix melts and the interaction between Ti3SiC2 and Cu occurs. The TiC x -Cu(Si) coatings that form show crystallites of both phases in the nano-range. In this case, rapid solidification of the molten fraction of the particles is responsible for the formation of the coatings with a nanostructured matrix. Due to the flexibility of the CCDS process, conditions of spraying were found such that a composite coating with very fine crystallites of the Cu(Si) matrix (30 nm) and a hardness of 273 HV could be obtained. 相似文献
26.
Energy-Efficient Routing for Connection-Oriented Traffic in Wireless Ad-Hoc Networks 总被引:2,自引:0,他引:2
We address the problem of routing connection-oriented traffic in wireless ad-hoc networks with energy efficiency. We outline the trade-offs that arise by the flexibility of wireless nodes to transmit at different power levels and define a framework for formulating the problem of session routing from the perspective of energy expenditure. A set of heuristics are developed for determining end-to-end unicast paths with sufficient bandwidth and transceiver resources, in which nodes use local information in order to select their transmission power and bandwidth allocation. We propose a set of metrics that associate each link transmission with a cost and consider both the cases of plentiful and limited bandwidth resources, the latter jointly with a set of channel allocation algorithms. Performance is measured through call blocking probability and average energy consumption and our detailed simulation model is used to evaluate the algorithms for a variety of networks. 相似文献
27.
The method used in Part I for the determination of Fourier coefficients of homogeneous functions is generalized here for nonhomogeneous functions. A number of examples from the field of power converter and inverter circuits are presented. Such special cases as harmonics of oscillations at the moments of valve's ignitions and extinctions are analyzed here. 相似文献
28.
Ilias Politis Michail Tsagkaropoulos Tasos Dagiuklas Stavros Kotsopoulos 《Mobile Networks and Applications》2008,13(3-4):274-284
This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet’s impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio—PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel). 相似文献
29.
Infolge einer Umwidmung eines ehemaligen Geschäftslokals in einen Kindergarten verlangte die Baubehörde eine Verbesserung der Horizontalaussteifung des in den 60er Jahren geschwächten Gründerzeitgebäudes. Die Erdbebensicherheit von Gründerzeithäusern wird erläutert. Die erfolgte Ertüchtigung des Gebäudes wird beschrieben. Strengthening of a Gründerzeit building for the load case earthquake. As a consequence of a rededication of a former salesroom to a kindergarten the building authority demanded a strengthening of the horizontal stability of the Gründerzeit building, which was weakened by removing walls in the 1960s. The earthquake resistance of Gründerzeit buildings is explained. The strengthening of the building is described. 相似文献
30.
Thibault Colombani Loek J. Eggermont Stephen M. Hatfield Zachary J. Rogers Mahboobeh Rezaeeyazdi Adnan Memic Michail V. Sitkovsky Sidi A. Bencherif 《Advanced functional materials》2021,31(37):2102234
Solid tumors are protected from antitumor immune responses due to their hypoxic microenvironments. Weakening hypoxia-driven immunosuppression by hyperoxic breathing of 60% oxygen has shown to be effective in unleashing antitumor immune cells against solid tumors. However, efficacy of systemic oxygenation is limited against solid tumors outside of lungs and has been associated with unwanted side effects. As a result, it is essential to develop targeted oxygenation alternatives to weaken tumor hypoxia as novel approaches to restore immune responses against cancer. Herein, injectable oxygen-generating cryogels (O2-cryogels) to reverse tumor-induced hypoxia are reported. These macroporous biomaterials are designed to locally deliver oxygen, inhibit the expression of hypoxia-inducible genes in hypoxic melanoma cells, and reduce the accumulation of immunosuppressive extracellular adenosine. The data show that O2-cryogels enhance T cell-mediated secretion of cytotoxic proteins, restoring the killing ability of tumor-specific cytotoxic T lymphocytes, both in vitro and in vivo. In summary, O2-cryogels provide a unique and safe platform to supply oxygen as a coadjuvant in hypoxic tumors and have the potential to improve cancer immunotherapies. 相似文献