On the error performance and channel capacity of a uniquely decodable coded FSO system over Malaga turbulence with pointing errors.

Our previous work has proved that the uniquely decodable code (UDC) has the ability of enhancing the throughput of a free space optical communication (FSO) system. This paper quantitatively analyzes the error performance and channel capacity of the UDC-FSO system under Malaga turbulence and pointing errors. We first propose the minimum distance of the superimposed patterns (MDSP) approximation to reveal the universal symbol error rate (SER) for UDC-FSO systems. A closed form expression of SER is further deduced for a special case of 2 TXs. Based on the deduced SER, the upper and lower bounds of bit error rate (BER) can be obtained. Additionally, the discrete channel capacity of the UDC-FSO system is defined and deduced according to different superposition patterns, as well as the channel capacity gain. Both simulation and experiment verify the accuracy of the MDSP and SER's expressions. It's also discovered that the channel capacity of the UDC-FSO system is superior to the conventional end-to-end (E2E) link, where maximal channel capacity is limited by the UDC codebooks.

Non-Iterative Multiscale Estimation for Spatial Autoregressive Geographically Weighted Regression Models.

Multiscale estimation for geographically weighted regression (GWR) and the related models has attracted much attention due to their superiority. This kind of estimation method will not only improve the accuracy of the coefficient estimators but also reveal the underlying spatial scale of each explanatory variable. However, most of the existing multiscale estimation approaches are backfitting-based iterative procedures that are very time-consuming. To alleviate the computation complexity, we propose in this paper a non-iterative multiscale estimation method and its simplified scenario for spatial autoregressive geographically weighted regression (SARGWR) models, a kind of important GWR-related model that simultaneously takes into account spatial autocorrelation in the response variable and spatial heterogeneity in the regression relationship. In the proposed multiscale estimation methods, the two-stage least-squares (2SLS) based GWR and the local-linear GWR estimators of the regression coefficients with a shrunk bandwidth size are respectively taken to be the initial estimators to obtain the final multiscale estimators of the coefficients without iteration. A simulation study is conducted to assess the performance of the proposed multiscale estimation methods, and the results show that the proposed methods are much more efficient than the backfitting-based estimation procedure. In addition, the proposed methods can also yield accurate coefficient estimators and such variable-specific optimal bandwidth sizes that correctly reflect the underlying spatial scales of the explanatory variables. A real-life example is further provided to demonstrate the applicability of the proposed multiscale estimation methods.

Likelihood based synchronization algorithms in optical pulse position modulation systems with photon-counting receivers.

Deep space optical communication (DSOC) is becoming a hot topic. Pulse position modulation (PPM) is an effective tool to realize DSOC benefiting from the feature of high sensitivity. In this paper, we analyze 2 × 1 optical PPM systems with photon-counting detectors, where the distance difference between the two links causes asynchronous superpositions at the receiving end. Two synchronization algorithms are proposed to estimate the time offsets of the two links, which are the optimal Global Maximum Likelihood Estimation (GMLE) and the suboptimal Integer Comparison - Fractional Likelihood Estimation (ICFLE). The complexities of the two methods are also compared. In order to measure the two proposed algorithms, the Cramer-Rao bounds (CRB) are derived. According to simulation results, both the two proposed algorithms approach the deduced CRBs. Furthermore, an equivalent experiment is designed to verify the feasibility and effectiveness of the proposed algorithms. It's also indicated that the proposed algorithms may be utilized in practical systems.

Dissolved organic matter in urban forestland soil and its interactions with typical heavy metals: a case of Daxing District, Beijing.

As an active substance, dissolved organic matter (DOM) acts a pivotal part in heavy metals (HMs) transportation from urban forestland soil to aquatic ecosystem. In this study, the soil samples from 35 individual subareas were scientifically collected with the aid of geographical information system (GIS) technology. UV-visible (UV-vis) and excitation-emission matrix (EEM)-related parameters suggested that the DOM in urban forestland soil mainly originated from terrestrial and microbial sources. Fluorescence quenching titration associated with parallel factor (PARAFAC) modeling was applied to quantify the complexation ability of four HMs (Cu, Cd, Pb, and Ni) and DOM in urban forestland soil. One fulvic-like (C1), two humic-like (C2 and C3), and one protein-like fluorophores (C4) were identified by EEM-PARAFAC modeling. Considerable differences in fluorescence quenching curves were observed between individual organic constituents and target HMs. Among the four HMs, addition of Cu(II) ions resulted in EEM spectra quenching of each PARAFAC-decomposed organic constituent. However, relatively strong fluorescence quenching phenomena were only detected in humic-like constituents (C2 and C3) with the titration of Pb(II) and Ni(II), which revealed that these types of organic constituent were predominantly responsible for Pb(II) and Ni(II) binding in urban forestland soil-derived DOM. Furthermore, considering the resistant nature of C2 and C3 constituents along with their significant quenching effects for the four target HMs, the concentrations of humic-like constituents in urban forestland soil may be a useful parameter to evaluate the potential risk of HMs immobilization and transformation.

The association of rs11190870 near LBX1 with the susceptibility and severity of AIS, a meta-analysis.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is the most common structural deformity of the spine. Genetics constitute largely to AIS, and the rs11190870 polymorphism has the potential for use in public health and clinical settings as a predictor of AIS risk. The aim of the present meta-analysis was to provide exhaustive evidence to evaluate the association of rs11190870 with the susceptibility and severity of adolescent idiopathic scoliosis (AIS) in multiple ethnic groups and different genders. MATERIALS AND METHODS: The professional databases, including PubMed, Embase, Social Sciences Citation Index, CINAHL, and International Bibliography of the Social Sciences, were searched from 1966 to October 2015. No language restriction was applied. Reference lists of all the selected articles were hand-searched for any additional studies. Three authors independently extracted data from all eligible studies. The data were analyzed by meta-analysis using fixed-effects or random-effects models with mean differences and risk ratios for continuous and dichotomous variables, respectively. RESULTS: Eight studies were included, and the pooled analysis suggested that the T genotype of SNP rs11190870 leads to a higher risk of AIS in multiple ethnic groups regardless of gender (Total:OR, 1.66, 95% CI 1.53, 1.79; I2 = 37.3%, P = 0.000, Female: OR, 1.62, 95% CI 1.50, 1.73; I2 = 26.7%, P = 0.000, Male: OR, 1.79, 95% CI 1.38, 2.20; I2 = 0.00%, P = 0.000). Additionally, the TT and TC genotype had a larger Cobb angle than those with the CC genotype in the overall and female Asian populations. CONCLUSION: A significant association of rs11190870 with AIS was observed in multiple ethnic groups regardless of gender. Additionally, a significant association was found between rs11190870 and curve severity in the overall and female Asian populations. Due to the limited data and clinical heterogeneity, further studies with large sample sizes are required.

Note: Design and capability verification of fillet triangle flexible support.

By increasing the section thickness of a triangular flexible hinge, this study focuses on optimal selection of parameters of fillet triangle flexible hinges and flexible support. Based on Castigliano's second theorem, the flexibility expression of the fillet triangle flexible hinge was derived. Then, the case design is performed, and the comparison of three types of flexible hinges with this type of flexible hinge was carried out. The finite element models of fillet triangle flexible hinges and flexible support were built, and then the simulation results of performance parameters were calculated. Finally, the experiment platform was established to validate analysis results. The maximum error is less than 8%, which verifies the accuracy of the simulation process and equations derived; also the fundamental frequency fits the requirements of the system. The fillet triangle flexible hinge is proved to have the advantages of high precision and low flexibility.

New approach to treating spinal cord injury using PEG-TAT-modified, cyclosporine-A-loaded PLGA/polymeric liposomes.

Cyclosporine-A (CsA) is an immunosuppressant agent that has shown effectiveness as a neuroprotective drug; however, it does not readily cross the blood-spinal cord barrier (BSCB), which constrains the clinical applications of CsA for the treatment of spinal cord injury (SCI). Our group recently tested the ability of novel polyethylene glycol (PEG)-transactivating-transduction protein (TAT)-modified CsA-loaded cationic multifunctional polymeric liposome-poly(lactic-co-glycolic acid) (PLGA) core/shell nanoparticles (PLGA/CsA NPs) to transport and deliver CsA across the BSCB to treat SCI. The PLGA/CsA NPs were successfully constructed. In vitro drug release studies have demonstrated that the sustained release of CsA from PLGA/CsA NPs occurs over ∼25 h. The in vivo study presented here showed that injured animals that received PLGA/CsA NPs through the tail vein, exhibited a significant up-regulation of growth-associated protein-43 (GAP-43) expression and an increased number of GAP-43-stained neurons compared with animals that received CsA or the vehicle alone. The improvement in neurological function was also evaluated by the Basso-Beattie-Bresnahan (BBB) open-field test. Moreover, fluorescein isothiocyanate (FITC)-attached PLGA/CsA NPs were successfully aggregated in the intact spinal cord 4 h after injection. Our data suggest that PLGA/CsA NPs have the potential for use as a new treatment method for SCI.

Spectroscopic Characteristics of Dissolved Organic Matter in Afforestation Forest Soil of Miyun District, Beijing.

In this study, soil samples collected from different plain afforestation time (1 year, 4 years, 10 years, 15 years, and 20 years) in Miyun were characterized, including total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), available K (K(+)), microbial biomass carbon (MBC), and dissolved organic carbon (DOC). The DOM in the soil samples with different afforestation time was further characterized via DOC, UV-Visible spectroscopy, excitation-emission matrix (EEM) fluorescence spectroscopy, and (1)H NMR spectroscopy. The results suggested that the texture of soil sample was sandy. The extracted DOM from soil consisted mainly of aliphatic chains and only a minor aromatic component. It can be included that afforestation can improve the soil quality to some extent, which can be partly reflected from the indexes like TOC, TN, TP, K(+), MBC, and DOC. And the characterization of DOM implied that UV humic-like substances were the major fluorophores components in the DOM of the soil samples, which consisted of aliphatic chains and aromatic components with carbonyl, carboxyl, and hydroxyl groups.

Photodynamic Therapy Mediated by Upconversion Nanoparticles to Reduce Glial Scar Formation and Promote Hindlimb Functional Recovery After Spinal Cord Injury in Rats.

Glial scar formation is one of the major consequences of spinal cord injury, which prevents the regenerated axons passing the injured area and forming effective synaptic connection. In this paper, we used photodynamic therapy (PDT), which was mediated by the upconversion nanoparticles coated with polyethylene glycol (PEG) and photosensitizer (UCNPs-PEGM540), to reduce the glial scar formation after spinal cord injury. The in vitro experimental results indicated that cultured astrocytes could be killed by using upconversion nanoparticles after excitation with near infrared light. By transplanting UCNPs-PEG-M540 into the margin area of injured epicenter of spinal cord, the recovery of rat's hindlimb function was evaluated in Basso, Beattie, Bresnahan locomotor rating scale, respectively. The improvement in microenvironment of the injured spinal cord was also evaluated by glial fibrillary acidic protein staining, neurofiliment staining, biotinylated dextran amine anterograde tracing and western blotting. Our results demonstrated that more regenerative axons of corticospinal tract were found to surround and pass through the injured cavity to the caudal cord with transplanting UCNPs-PEG-M540 into the injured spinal cord. In conclusion, our results strongly suggested that upconversion nanoparticles combined with photodynamic therapy can promote functional recovery in rats' hindlimbs by reducing the formation of glial scar and promoting remyelination of injured axons.

Nonsteroidal Anti-inflammatory Drugs as Prophylaxis for Heterotopic Ossification after Total Hip Arthroplasty: A Systematic Review and Meta-Analysis.

Heterotopic ossification (HO) is a frequent complication after total hip arthroplasty (THA). Nonsteroidal anti-inflammatory drugs (NSAIDs) have been used as routine prophylaxis for HO after THA. However, the efficacy of NSAIDs on HO, particularly selective NSAIDs versus nonselective NSAIDs, is uncertain.We searched PubMed, Embase, the Cochrane Central Register of Controlled Trials, and clinicaltrials.gov to identify randomized controlled trials with respect to HO after THA. Two reviewers extracted the data and estimated the risk of bias. For the ordered data, we followed the Bayesian framework to calculate the odds ratio (OR) with a 95% credible interval (CrI). For the dichotomous data, the OR and 95% confidence interval (CI) were calculated using Stata version 12.0. The subgroup analyses and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach were used.A total of 1856 articles were identified, and 21 studies (5995 patients) were included. In the NSAIDs versus placebo analysis, NSAIDs could decrease the incidence of HO, according to the Brooker scale (OR = 2.786, 95% CrI 1.879-3.993) and Delee scale (OR = 9.987, 95% CrI 5.592-16.17). In the selective NSAIDs versus nonselective NSAIDs analysis, there was no significant difference (OR = 0.7989, 95% CrI 0.5506-1.125) in the prevention of HO. NSAIDs could increase discontinuation caused by gastrointestinal side effects (DGSE) (OR = 1.28, 95% CI 1.00-1.63, P = 0.046) more than a placebo. Selective NSAIDs could decrease DGSE (OR = 0.48, 95% CI 0.24-0.97, P = 0.042) compared with the nonselective NSAIDs. There was no significant difference with respect to discontinuation caused by non-gastrointestinal side effects (DNGSE) in NSAIDs versus a placebo (OR = 1.16, 95% CI 0.88-1.53, P = 0.297) and in selective NSAIDs versus nonselective NSAIDs (OR = 0.83, 95% CI 0.50-1.37, P = 0.462).NSAIDs might reduce the incidence of HO and increase DGSE in the short-term.