Two-level coding for efficient digital radio-over-fiber transmission with unequal bit protection.

The digital radio-over-fiber (D-RoF) transmission with two-level coding (TLC) is proposed and demonstrated in this Letter. A joint design considering the importance of quantization bits, the protection ability of forward error correction (FEC), and the bit error ratio of quadrature amplitude modulation (QAM) symbols is realized. In TLC-based D-RoF systems, the more significant bits among quantization bits are protected by a FEC and are assigned to the least reliable bits of modulated QAM symbols. Conversely, the less significant bits, without FEC protection, are allocated to the more reliable bits of QAM symbols. Experiments on an 11-km standard single-mode fiber transmission are conducted to evaluate the performance. The results indicate that, with a maximum iteration number of 2, compared to the conventional bit-interleaved coded modulation (BICM) with all bits encoded, the D-RoF based on TLC attains nearly identical performance under the 0.34% error vector magnitude threshold of 65536QAM wireless signals, specifically achieving complexity reductions of 54.55% and 67.66% for 16QAM and 64QAM optical transmissions, respectively.

Deep Reinforcement Learning-Based Resource Management in Maritime Communication Systems.

With the growing maritime economy, ensuring the quality of communication for maritime users has become imperative. The maritime communication system based on nearshore base stations enhances the communication rate of maritime users through dynamic resource allocation. A virtual queue-based deep reinforcement learning beam allocation scheme is proposed in this paper, aiming to maximize the communication rate. More particularly, to reduce the complexity of resource management, we employ a grid-based method to discretize the maritime environment. For the combinatorial optimization problem of grid and beam allocation under unknown channel state information, we model it as a sequential decision process of resource allocation. The nearshore base station is modeled as a learning agent, continuously interacting with the environment to optimize beam allocation schemes using deep reinforcement learning techniques. Furthermore, we guarantee that grids with poor channel state information can be serviced through the virtual queue method. Finally, the simulation results provided show that our proposed beam allocation scheme is beneficial in terms of increasing the communication rate.

Exosomal MiR-381 from M2-polarized macrophages attenuates urethral fibroblasts activation through YAP/GLS1-regulated glutaminolysis.

OBJECTIVE AND DESIGN: Post-traumatic urethral stricture is a clinical challenge for both patients and clinicians. Targeting glutamine metabolism to suppress excessive activation of urethral fibroblasts (UFBs) is assumed to be a potent and attractive strategy for preventing urethral scarring and stricture. MATERIAL OR SUBJECTS: In cellular experiments, we explored whether glutaminolysis meets the bioenergetic and biosynthetic demands of quiescent UFBs converted into myofibroblasts. At the same time, we examined the specific effects of M2-polarized macrophages on glutaminolysis and activation of UFBs, as well as the mechanism of intercellular signaling. In addition, findings were further verified in vivo in New Zealand rabbits. RESULTS: It revealed that glutamine deprivation or knockdown of glutaminase 1 (GLS1) significantly inhibited UFB activation, proliferation, biosynthesis, and energy metabolism; however, these effects were rescued by cell-permeable dimethyl α-ketoglutarate. Moreover, we found that exosomal miR-381 derived from M2-polarized macrophages could be ingested by UFBs and inhibited GLS1-dependent glutaminolysis, thereby preventing excessive activation of UFBs. Mechanistically, miR-381 directly targets the 3'UTR of Yes-associated protein (YAP) mRNA to reduce its stability at the transcriptional level, ultimately downregulating expression of YAP, and GLS1. In vivo experiments revealed that treatment with either verteporfin or exosomes derived from M2-polarized macrophages significantly reduced urethral stricture in New Zealand rabbits after urethral trauma. CONCLUSION: Collectively, this study demonstrates that exosomal miR-381 from M2-polarized macrophages reduces myofibroblast formation of UFBs and urethral scarring and stricture by inhibiting YAP/GLS1-dependent glutaminolysis.

Network localization of transient global amnesia beyond the hippocampus.

BACKGROUND: Transient global amnesia is common in the older adult, but the cause and mechanism remain unclear. Focal brain lesions allow for causal links between the lesion location and resulting symptoms, and we based on the reported TGA-causing lesions and used lesion network mapping to explore the causal neuroanatomical substrate of TGA. METHODS: Fifty-one cases of transient global amnesias with DWI lesions from the literature were identified, and clinical data were extracted and analyzed. Next, we mapped each lesion volume onto a reference brain and computed the network of regions functionally connected to each lesion location using a large normative connectome dataset. RESULTS: Lesions primarily occurred in the hippocampus, and in addition to the hippocampus, there are also other locations of TGA-causing lesions such as the cingulate gyrus, anterior thalamic nucleus (ATN), putamen, caudate nucleus, corpus callosum, fornix. More than 90% of TGA-causing lesions inside the hippocampus were functionally connected with the default mode network (DMN). CONCLUSION: Structural abnormality in the hippocampus was the most consistently reported in TGA, and besides the hippocampus, lesions occurring at several other brain locations also could cause TGA. The DMN may also be involved in the pathophysiology of TGA. According to the clinical and neuroimaging characteristics, TGA may be a syndrome with multiple causes and cannot be treated simply as a subtype of TIA.

Asymmetric point-to-multipoint coherent architecture with a frequency aliasing recovery algorithm for cost-constraint short-reach access networks.

An asymmetric point-to-multipoint (PTMP) coherent architecture combined with a frequency aliasing recovery (FAR) algorithm is proposed for cost-constraint short-reach access networks. In this architecture, the uplink transmitters are simplified significantly with the uplink dual-polarization four-level pulse amplitude modulation (DP-PAM4) and downlink DP quadrature phase shift keying (DP-QPSK) asymmetric transmission design. Digital to analog converters (DACs) and radio frequency (RF) drivers are reduced by half, and in-phase and quadrature modulators (IQMs) are replaced by Mach-Zehnder modulators (MZMs), saving four MZ interferometers (MZIs). Furthermore, based on the asymmetric architecture, the FAR algorithm can recover signals from frequency aliasing caused by frequency offset (FO), even when half of the signal spectrum is aliased. This algorithm enables the asymmetric architecture to narrow down guard bands between subcarriers or even overlap the subcarriers, saving the receiver bandwidth at the aggregation/hub side. The performance of the asymmetric uplink DP-PAM4 transmission with the FAR algorithm is evaluated in both simualations and experiments. The effects of laser linewidths and IQ skew on the performance of the FAR algorithm are also analyzed. Simulation results show the algorithm can recover 16 Gbaud and 32 Gbaud signal from 8 GHz and 16 GHz aliasing, respectively. In the experiments with 10 km fiber transmissions, the FAR algorithm can recover 10 Gbaud signals from 5 GHz frequency aliasing, saving about 20.83% of the total receiver bandwidth in a 2-subcarrier system.

Coherent digital-analog radio-over-fiber (DA-RoF) system with a CPRI-equivalent data rate beyond 1 Tb/s for fronthaul.

We propose and experimentally demonstrate a coherent digital-analog radio-over-fiber (DA-RoF) system and achieve the transmission of Tb/s common public radio interface (CPRI)-equivalent data rate for fronthaul. The proposed coherent DA-RoF system includes DA-RoF modulation, demodulation and DA-RoF compatible coherent digital signal processing (DSP) blocks. A theoretical analysis of the DA-RoF scheme together with parameter optimization is accomplished as well. In the experiment, a 25 Gbaud DA-RoF signal with 1 Tb/s CPRI-equivalent data rate is transmitted in the system, satisfying the error vector magnitude (EVM) requirement for 256-quadrature amplitude modulation (QAM) signal transmission. With the symbol rate reduced to 10 Gbaud, an EVM below 2.5% is achieved, which meets the requirement for 1024-QAM transmission. The experimental results show that the coherent DA-RoF system is a promising solution for future fronthaul.

Cascaded digital-analog radio-over-fiber for efficient SNR scaling at >10†dB per extra bandwidth.

Efficient signal-to-noise ratio (SNR) and spectral efficiency (SE) trade-off can offer fundamental guiding law for future large-capacity and high-fidelity mobile fronthaul. In this Letter, we propose and experimentally demonstrate a cascaded digital-analog radio-over-fiber (CDA-RoF) scheme, which transmits digitized and analog segments using time-division-multiplexing aggregation. Specifically, multiple digital parts generated by a rounding function describe the main features of the original waveform, while the residual error is magnified and delivered as analog RoF with SE advantage. Based on a 20-GHz O-band directly modulated laser (DML), an SNR enhancement of >10 dB is observed for each extra bandwidth. Up to 70.4-dB SNR is also achieved for a 3.5-GHz 1048576-ary quadrature amplitude modulation (1048576-QAM) signal after 20-km standard single-mode fiber (SSMF) transmission.

Ultrasensitive Uracil-DNA Glycosylase Activity Assay and Its Inhibitor Screening Based on Primer Remodeling Jointly via Repair Enzyme and Polymerase.

The development of isothermal nucleic acid amplification techniques has great significance for highly sensitive biosensing in modern biology and biomedicine. A facile and robust exponential rolling circle amplification (RCA) strategy is proposed based on primer-remodeling amplification jointly via a repair enzyme and polymerase, and uracil-DNA glycosylase (UDG) is selected as a model analyte. Two kinds of complexes, complex I and complex II, are preprepared by hybridizing a circular template (CT) with a uracil-containing hairpin probe and tetrahydrofuran abasic site mimic (AP site)-embedded fluorescence-quenched probe (AFP), respectively. The target UDG specifically binds to complex I, resulting in the generation of an AP site, followed by cleavage via endonuclease IV (Endo IV) and the successive trimming of unmatched 3' terminus via phi29 DNA polymerase, thus producing a useable primer-CT complex that actuates the primary RCA. Then, numerous complex II anneal with the first-generation RCA product (RP), generating a complex II-RP assembly containing AP sites within the DNA duplex. With the aid of Endo IV and phi29, AFP, as a pre-primer in complex II, is converted into a mature primer to initiate additional rounds of RCA. So, countless AFPs are cleaved, releasing remarkably strong fluorescent signals. The biosensor is demonstrated to enable rapid and accurate detection of the UDG activity with an improved detection limit as low as 4.7 × 10-5 U·mL-1. Moreover, this biosensor is successfully applied for UDG inhibitor screening and complicated biological samples analysis. Compared to the previous exponential RCA methods, our proposed strategy offers additional advantages, including excellent stability, optional design of CT, and simplified operating steps. Therefore, this proposed strategy may create a useful and practical platform for ultrasensitive detection of low levels of analytes in clinical diagnosis and fundamental biomedicine research.

Differentiation of disaccharide isomers via a combination of IR and UV photodissociation mass spectrometry.

RATIONALE: The challenge of glycan identification due to their structural complexity and diversity has profited enormously from recent developments in mass spectrometry (MS)-related methods. For photodissociation MS, infrared (IR) and ultraviolet (UV) lasers can generate complementary fragment ions, so an effective combination of the two methods may provide rich and valuable fragmentation patterns for glycan analysis. METHODS: A 7.0 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer equipped with a double-beam laser system was applied for the experiments. 3,5-Diiodo-L-tyrosine was selected as the assistant molecule to form complex ions with ten isomeric disaccharides through electrospray ionization. The complex ions were further isolated and irradiated by IR and UV lasers separately or continuously in the FTICR cell. RESULTS: By combining the two complementary fragment spectra generated from the IR and UV lasers, a clear identification of all the ten isomers was achieved using their binary codes based on their fragmentation patterns. The double-beam method simplifies the experiment by introducing the two lasers sequentially in one experiment, providing richer fragmentation patterns and making the full discrimination easier. CONCLUSIONS: This study demonstrates the capabilities of the combination of IR and UV photodissociation MS in the identification of diverse glycan isomers. The double-beam photodissociation method described here distinguished compositional, configurational and connectivity disaccharide isomers successfully. Compared with the data accumulation method based on separate IR and UV experiments, this method is simpler, faster, more flexible and also characterized by richer fragmentation patterns.

Versatile Double-Beam Confocal Laser System Combined with a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer for Photodissociation Mass Spectrometry and Spectroscopy.

Both infrared multiphoton dissociation (IRMPD) and ultraviolet photodissociation (UVPD) play important roles in tandem mass spectrometry and the action spectroscopy of organic and biological molecules. A flexible combination of the two methods may provide researchers with more versatile and powerful ion activation/dissociation choices for structural characterization and spectroscopic studies. Here, we report the integration of two tunable lasers with a Fourier transform ion cyclotron resonance mass spectrometer in a confocal mode, which offers multiple capabilities for photon activation/dissociation experiments. The two overlapped beams can be introduced into the cell individually, sequentially, or simultaneously, providing highly flexible and diverse activation schemes. The setup can also measure the UVPD or IRMPD action spectra of fragment ions generated by previous photon dissociation processes. In addition, the multistage tandem-in-time mass spectrometry performance up to MS4, including three different activation methods in a single cell, has also been demonstrated.

Structural Diversity of Di-Metalized Arginine Evidenced by Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy in the Gas Phase.

Although metal cations are prevalent in biological media, the species of multi-metal cationized biomolecules have received little attention so far. Studying these complexes in isolated state is important, since it provides intrinsic information about the interaction among them on the molecular level. Our investigation here demonstrates the unexpected structural diversity of such species generated by a matrix-assisted laser desorption ionization (MALDI) source in the gas phase. The photodissociation spectroscopic and theoretical study reflects that the co-existing isomers of [Arg+Rb+K-H]+ can have energies ≥95 kJ/mol higher than that of the most stable one. While the result can be rationalized by the great isomerization energy barrier due to the coordination, it strongly reminds us to pay more attention to their structural diversities for multi-metalized fundamental biological molecules, especially for the ones with the ubiquitous alkali metal ions.

Fe(III)-Catalyzed Decarboxylative C3-Difluoroarylmethylation of Coumarins with α,α-Difluoroarylacetic Acids.

A facile Fe(III)-catalyzed oxidative decarboxylative radical coupling reaction of α,α-difluoroarylacetic acids with coumarins has been developed. This transformation, which provides a series of C-3 difluoroarylmethylated coumarins containing various functional groups in moderate-to-good yields, features easily accessible starting materials and operational simplicity.

Early diagnostic value of serum procalcitonin levels for catheter-related blood stream infection in first-ever acute ischemic stroke patients.

OBJECTIVE: The traditional approaches for diagnosing catheter-related bloodstream infection(CRBSI) is time consuming, which could not meet the clinical requirement. Our aim was to investigate the value of serum procalcitonin(PCT) in predicting CRBSI in first-ever acute ischemic stroke patients with central venous catheters (CVCs). METHODS: This was a retrospective study. First-ever acute ischemic stroke patients hospitalized in neurological intensive care unit(NICU) of Aerospace Center Hospital and NICU of Beijing Chaoyang Hospital during January 2010 and December 2017 with clinically suspected CRBSI were enrolled. Peripheral blood white blood cell (WBC) count, neutrophils percentage(NE%), the levels of serum PCT, dwell time of catheterization and outcome of the patients were collected. According to the diagnosis of CRBSI or not, they were divided into CRBSI group and no CRBSI group. We used receiver operating characteristic curve (ROC) to evaluate the value of serum PCT levels in predicting CRBSI in patients with clinically suspected CRBSI. RESULTS: Forty-five patients with suspected CRBSI were included in this study, and 13 patients were diagnosed with CRBSI. Comparing to those in no CRBSI group, the maximum body temperature (Tmax) (p = 0.036) and the PCT levels (P = 0.013) in CRBSI group were both significantly higher. The area under ROC of the serum PCT levels and the Tmax to predict the CRBSI were 0.803 (0.95CI,0.660-0.946) and 0.680 (0.95CI,0.529-0.832) respectively. The PCT cut-off value was 0.780 ng/ml, with the sensitivity 69.23%, specificity 87.50%, positive predictive values 69.23% and negative predictive values 87.50%. CONCLUSION: It could be helpful to adopt PCT as a rapid diagnostic biomarker for first-ever acute stroke patients with suspected CRBSI.

Application of Infrared Multiple Photon Dissociation (IRMPD) Spectroscopy in Chiral Analysis.

In recent years, methods based on photodissociation in the gas phase have become powerful means in the field of chiral analysis. Among them, infrared multiple photon dissociation (IRMPD) spectroscopy is a very attractive one, since it can provide valuable spectral and structural information of chiral complexes in addition to chiral discrimination. Experimentally, the method can be fulfilled by the isolation of target diastereomeric ions in an ion trap followed by the irradiation of a tunable IR laser. Chiral analysis is performed by comparing the difference existing in the spectra of enantiomers. Combined with theoretical calculations, their structures can be further understood on the molecular scale. By now, lots of chiral molecules, including amino acids and peptides, have been studied with the method combined with theoretical calculations. This review summarizes the relative experimental results obtained, and discusses the limitation and prospects of the method.

Robust and highly specific fluorescence sensing of Salmonella typhimurium based on dual-functional phi29 DNA polymerase-mediated isothermal circular strand displacement polymerization.

A simple and robust fluorescence sensing strategy has been developed for the detection of pathogenic bacteria by the combination of the dual functionality of phi29 DNA polymerase with isothermal circular strand displacement polymerization (ICSDP). The strategy relies on target-triggered formation of a mature primer that initiates the cyclic strand displacement polymerization reaction with the aid of dual functional phi29; thus, amplified detection of the target can be achieved. To our knowledge, this work is the first report where dual functional phi29-assisted ICSDP has been employed for fluorescence sensing of pathogenic bacteria. It is worth noting that a hairpin pre-primer is introduced that can be trimmed into a mature primer for initiating ICSDP via the 3' → 5' proofreading exonuclease activity of phi29, which contributes to the ultrahigh specificity of the strategy owing to the elimination of the unwished nonspecific extension. On the basis of the present amplification strategy, our biosensor exhibits excellent specificity and sensitivity toward S. typhimurium with an excellent detection limit as low as 1.5 cfu mL-1. In addition, the strategy offers the advantages of a simplified operation, shortened analysis time, and highly sensitive detection of pathogens with only a one-step reaction. Furthermore, by redesigning the corresponding binding molecules, the proposed strategy can be easily extended for the detection of a wide spectrum of analytes. Hence, the dual functional phi29-assisted ICSDP strategy indeed creates a robust and convenient fluorescence sensing platform for the identification of pathogenic bacteria and related food safety analysis.

The protective effect of persistent trigeminal artery in patients with ischemic stroke.

BACKGROUND: Almost all case reports related to persistent trigeminal artery indicated that the existence of persistent trigeminal artery may increase the risk of ischemic stroke. However our case demonstrated that the persistent trigeminal artery may also play a protective role in preventing severe ischemic stroke by functioning as collateral circulation. CASE PRESENTATION: We reported a patient with left internal carotid artery occlusion with persistent trigeminal artery manifesting only as a minor acute ischemia stroke exhibiting acute onset of dizziness and difficulty in walking. Brain MRI showed two small areas of restricted diffusion on diffusion-weighted imaging in the left hemisphere. The digital subtraction angiography showed his left middle cerebral artery and bilateral anterior cerebral artery were supplied by the basilar artery via a persistent trigeminal artery. Furthermore, CT perfusion showed no remarkable difference between the two hemispheres. CONCLUSIONS: Persistent trigeminal artery may have a protective role in the setting of an acquired occlusion of homolateral internal carotid artery. Therefore, it is important to fully assess the presence of the persistent trigeminal artery in acute ischemic stroke.

Enhancement of anti-diabetic activity of pomelo peel by the fermentation of Aspergillus oryzae CGMCC23295: In vitro and in silico docking studies.

In this work, pomelo peel was fermented by Aspergillus oryzae CGMCC23295 to enhance its anti-diabetic properties. Results showed the total phenolic and flavonoids contents, ferric reducing antioxidant power (FRAP), scavenging capacities against 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH) and hydroxyl radicals, as well as inhibitory abilities against α-amylase and α-glucosidase of pomelo peel were increased and fermentation for 8 days was the best. Additionally, the fermented sample could also enhance the glucose consumption and glycogen of HepG2 cell. Based on UPLC-MS/MS analysis, binding energy calculation, concentration determination and IC50 measurement, purpurin, apigenin, genistein, and paxilline could be concluded to be the main compounds to enhance the inhibition activities of fermented sample against α-amylase and α-glucosidase. Furthermore, computational studies were performed to reveal the the binding site and molecular interactions between paxilline and α-amylase, as well as purpurin and α-glucosidase. These findings provide a base for the utilization and valorization of pomelo peels as functional food additives by fermentation.

Rh nanoparticle catalyzed hydroaminomethylation of 1-octene in thermoregulated ionic liquid and organic biphasic system.

Thermoregulated ionic liquid and organic biphasic system composed of ionic liquid [CH3(OCH2 CH2)22N+Et3][CH3SO3-] (abbreviated as IL(PEG1000)) containing IL(PEG1000)-stabilized Rh nanoparticles and organic solvent, which allows for not only highly efficient homogeneous reaction but also an easy biphasic separation, was applied to the hydroaminomethylation of 1-octene for the first time. Under the optimized conditions, the conversion of 1-octene and the amine selectivity were 100% and 90%, respectively. After reaction, the Rh nanoparticle catalyst could be easily separated by simple decantation and reused for four times without evident loss in activity.

The impacts of tidal wetland loss and coastal development on storm surge damages to people and property: a Hurricane Ike case-study.

Coastal wetlands protect communities during hurricanes by reducing storm surge flooding and damages. Previous studies have quantified surge reduction benefits of wetlands, but there is less understanding of how the combination of wetland loss and coastal development influences the spatial distribution of flood extents and damages. In this study we integrate a high-resolution 2-D hydrodynamic model with land-use/land-cover change analyses to assess the effects of total wetland loss, decadal wetland loss, and coastal development on storm surge damages in Galveston Bay, Texas. We measure storm surge flood extents from Hurricane Ike for three scenarios: (i) 2008 Baseline; (ii) 2008 No Wetlands, and (iii) 2019 "Present-day H. Ike". We find that during Hurricane Ike in 2008, the total loss of coastal wetlands would have increased damages by a net ~ USD $934 million or 12.8% of baseline damages. For the 2019 Present-day H. Ike scenario, we found very few wetlands were lost between 2008 and 2019. If Hurricane Ike had occurred in 2019, damages would have been higher by ~ $2.52 billion or 34.6%, almost entirely due to increased real estate value and new coastal development. Our findings suggest that, while increase in economic exposure is a key driver of storm surge risks in Galveston Bay, effective wetland conservation continues to reduce these risks.

Decoupled neural network training with re-computation and weight prediction.

To break the three lockings during backpropagation (BP) process for neural network training, multiple decoupled learning methods have been investigated recently. These methods either lead to significant drop in accuracy performance or suffer from dramatic increase in memory usage. In this paper, a new form of decoupled learning, named decoupled neural network training scheme with re-computation and weight prediction (DTRP) is proposed. In DTRP, a re-computation scheme is adopted to solve the memory explosion problem, and a weight prediction scheme is proposed to deal with the weight delay caused by re-computation. Additionally, a batch compensation scheme is developed, allowing the proposed DTRP to run faster. Theoretical analysis shows that DTRP is guaranteed to converge to crical points under certain conditions. Experiments are conducted by training various convolutional neural networks on several classification datasets, showing comparable or better results than the state-of-the-art methods and BP. These experiments also reveal that adopting the proposed method, the memory explosion problem is effectively solved, and a significant acceleration is achieved.