Asymptotic Capacity of Large Relay Networks with Conferencing Links

In this correspondence, we consider a half-duplex large relay network, which consists of one source-destination pair and $N$ relay nodes, each of which is connected with a subset of the other relays via signal-to-noise ratio (SNR)-limited out-of-band conferencing links. The asymptotic achievable rates of two basic relaying schemes with the "$p$-portion" conferencing strategy are studied: For the decode-and-forward (DF) scheme, we prove that the DF rate scales as $\mathcal{O} (\log (N))$; for the amplify-and-forward (AF) scheme, we prove that it asymptotically achieves the capacity upper bound in some interesting scenarios as $N$ goes to infinity.Comment: submitted to IEEE Transactions on Communication

Asymptotic Capacity of Large Fading Relay Networks with Random Node Failures

To understand the network response to large-scale physical attacks, we investigate the asymptotic capacity of a half-duplex fading relay network with random node failures when the number of relays $N$ is infinitely large. In this paper, a simplified independent attack model is assumed where each relay node fails with a certain probability. The noncoherent relaying scheme is considered, which corresponds to the case of zero forward-link channel state information (CSI) at the relays. Accordingly, the whole relay network can be shown equivalent to a Rayleigh fading channel, where we derive the $\epsilon$-outage capacity upper bound according to the multiple access (MAC) cut-set, and the $\epsilon$-outage achievable rates for both the amplify-and-forward (AF) and decode-and-forward (DF) strategies. Furthermore, we show that the DF strategy is asymptotically optimal as the outage probability $\epsilon$ goes to zero, with the AF strategy strictly suboptimal over all signal to noise ratio (SNR) regimes. Regarding the rate loss due to random attacks, the AF strategy suffers a less portion of rate loss than the DF strategy in the high SNR regime, while the DF strategy demonstrates more robust performance in the low SNR regime.Comment: 24 pages, 5 figures, submitted to IEEE Transactions on Communication

Characterization of Laser-Resistant Port Wine Stain Blood Vessels Using In Vivo Reflectance Confocal Microscopy.

Background and objectivesPort wine stain (PWS) is a congenital vascular malformation of the human skin. Laser is the treatment of choice for PWS. Laser-resistant PWS is one crucial factor accounting for inadequate treatment outcome, which needs to be fully characterized. This study aims to quantitatively characterize the morphology of laser-resistant PWS blood vessels in the upper papillary dermis using in vivo reflectance confocal microscopy (RCM).Study design/materials and methodsA total of 42 PWS subjects receiving laser treatment from August 2016 through July 2018 were enrolled into this study. Thirty-three subjects had facial PWS; nine had extremity PWS. All subject's PWS received multiplex 585/1,064 nm laser treatment. RCM images were taken before and after treatment. The density, diameter, blood flow, and depth of PWS blood vessels were analyzed.ResultsWe found 44.4% PWS on the extremities (four out of nine subjects) were laser-resistant, which was significantly higher (P < 0.001) when compared with those PWS on the face (15.2%, 5 out of 33 subjects). The laser-resistant facial PWS blood vessels had significantly higher blood flow (1.35 ± 0.26 U vs. 0.89 ± 0.22 U, P < 0.001), larger blood vessel diameters (109.60 ± 18.24 µm vs. 84.36 ± 24.04 µm, P = 0.033) and were located deeper in the skin (106.01 ± 13.87 µm vs. 87.82 ± 12.57 µm, P < 0.001) in the skin when compared with laser-responsive PWS on the face. The average PWS blood vessel density (17.01 ± 4.63/mm2 vs. 16.61 ± 4.44/mm2 , P = 0.857) was not correlated to the laser resistance.ConclusionsLaser-resistant PWS blood vessels had significantly higher blood flow, larger diameters, and were located deeper in the skin. RCM can be a valuable tool for a prognostic evaluation on laser-resistant lesions before treatment, thereby providing guidance for tailored laser treatment protocols, which may improve the therapeutic outcome. The limitations for this study include relative small sample size and acquisitions of different blood vessels before and after 2 months of treatment. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc

Synthetic Studies of Iriomoteolide-1A Total Synthesis of Alotaketal A and an Antifungal O-Hydroxy-P-Quinone Methide Diterpenoid

Natural products are a rich source of compounds with interesting structures and biological activities. Three bioactive natural products, iriomoteolide-1a, alotaketal A, and an unnamed quinone methide diterpenoid, attracted our attention during our course of exploring natural products as potential leads for biomedical discovery. The structure of iriomoteolide-1a had been misassigned, but the potent cytotoxicity reported for this natural product warranted further studies to elucidate its true structure. As part of our effort toward this goal, we finished the total synthesis of a diastereomer of iriomoteolide-1a. Our total synthesis featured a lithium acetylide-chloroformate coupling to assemble the alkyne and chloroformate fragments, the ring closing metathesis to exclusively generate the 15E-macrocyclic diolide, and a SmI_(2)-mediated intramolecular reductive allylation to form the cyclic hemiketal. The bioactivities of this diastereomer were evaluated, but only weak inhibition of cell proliferation was observed at 10 µM toward HeLa and PC3 cell lines. Alotaketal A was reported to potently (EC_(50) = 18 nM) activate the cAMP (cyclic adenosine monophosphate) signaling pathway in HEK293 cells transformed with the pHTS-CRE plasmid. Our synthetic efforts toward this natural product culminated in the first enantioselective total synthesis of (-)-alotaketal A. Our total synthesis employed both intra- and inter-molecular reductive allylation of esters for assembling the bicyclic lactone and coupling the fragments. A Hg(OAc)_(2)-mediated allylic mercuration was used to introduce the C22-hydroxyl group. The subtle influence of substituents over the course of the spiroketalization process was revealed. The synthesis confirmed the relative and absolute stereochemistry of (-)-alotaketal A and allowed verification of alotaketal A’s effect over cAMP signaling using reporter-based FRET imaging assays with HEK293 cells. Our studies also revealed alotaketal A’s unique activity in selectively targeting nuclear PKA signaling in living cells. Our synthetic efforts toward the unnamed quinone methide diterpenoid 1.67 led to the first total synthesis of this potent antifungal product (MIC = 0.19 µM). Our total synthesis was highlighted by a Stille coupling to introduce the allyl group, a lithium/naphthalene-mediated coupling reaction for fragment assembling, and a BBr3-mediated one-pot bis-demethylation and intramolecular Friedel-Crafts alkylation to build the tricyclic molecular framework. Our preliminary structure-activity relationship study showed that the 2'-hydroxyethyl side chain of the natural product was nonessential to its antifungal activity

Discussion on the Construction of Ecological Water Network in Guangxi Province of China

The water network plays an important role in maintaining the stability of regional water resource and ecological environment. It is also affecting the harmonious development between environment and economy. Guangxi is one of the provinces with relatively rich water resources in China, while the ecological water network exists deficiencies and faces challenges. The current situation and defects of ecological water network in Guangxi province will be discussed. By studying the experience of the establishing and the preserve of ecological water network in various regions at home and abroad, some suggestions and targeted measures will be mentioned for a better ecological water network in Guangxi

A multi-channel photometric detector for multi-component analysis in flow injection analysis

The detector, a multi-channel photometric detector, described in this paper was developed using multi-wavelength LEDs (light emitting diode) and phototransistors for absorbance measurement controlled by an Intel 8031 8-bit single chip microcomputer. Up to four flow cells can be attached to the detector. The LEDs and phototransistors are both inexpensive, and reliable. The results given by the detector for simultaneous determination of trace amounts of cobalt and cadmium in zinc sulphate electrolyte are reported. Because of the newly developed detector, this approach employs much less hardware apparatus than by employing conventional photometric detectors

Effects of Mountain Rivers Cascade Hydropower Stations on Water Ecosystems

China is rich in hydropower resources, and mountain rivers have abundant water resources and huge development potential, which have a profound impact on the pattern of water resources allocation in China. As the main way of water resources and hydropower development, the construction of cascade hydropower stations, while meeting the requirements of water resources utilization for social development, has also brought adverse effects on river ecosystems. Therefore, the impact of the construction of cascade hydropower stations on mountainous river ecosystems, where the minimum ecological flow of rivers must be ensured and reviewed. In addition, this paper proposed the deficiencies and outlooks for cascade hydropower stations based on previous research results