Recent emphasis on green communications has generated great interest in the investigations of energy harvesting communications and networking. Energy harvesting from ambient energy sources can ...potentially reduce the dependence on the supply of grid or battery energy, providing many attractive benefits to the environment and deployment. However, unlike the conventional stable energy, the intermittent and random nature of the renewable energy makes it challenging in the realization of energy harvesting transmission schemes. Extensive research studies have been carried out in recent years to address this inherent challenge from several aspects: energy sources and models, energy harvesting and usage protocols, energy scheduling and optimization, implementation of energy harvesting in cooperative, cognitive radio, multiuser and cellular networks, etc. However, there has not been a comprehensive survey to lay out the complete picture of recent advances and future directions. To fill such a gap, in this paper, we present an overview of the past and recent developments in these areas and highlight a number of possible future research avenues.
Flavonoids are bioactive phytochemicals that exhibit protective potential against cutaneous inflammation and photoaging. We selected eight flavonoid aglycones or glycosides to elucidate the chemistry ...behind their skin absorption capability through experimental and computational approaches. The skin delivery was conducted using nude mouse and pig skins mounted on an in vitro Franz cell assembly. The anti-inflammatory activity was examined using the O₂
.
The use of energy harvesting cooperative relays is a promising solution to battery-limited wireless networks. In this paper, we consider a cooperative system in which one source node transmits data ...to one destination with the assistance of an energy harvesting decode-and-forward (DF) relay node. Our objective is to minimize the long-term average symbol error rate (SER) performance through a Markov decision process (MDP) framework. By doing so, we find the optimal stochastic power control at the relay that adapts the transmission power to the changes of energy harvesting, battery, channel, and decoding states. We derive a finite-integral expression for the exact average SER of the cooperative system. Further insights are gained by analyzing the asymptotic average SER and its lower and upper bounds at high signal-to-noise ratio (SNR), and the performance is eventually characterized by the occurrence probability of the relay's actions at the worst channel states in the MDP. We also show that the optimal cooperative policy at asymptotically high SNR follows a threshold-type structure, i.e., the relay spends the harvested energy only when the signal is successfully decoded and the source is faced with the worst channel condition in its direct link. Using these observations to quantify the diversity gain and the energy harvesting gain, we reveal that full diversity is guaranteed if and only if the probability of harvesting zero energy quantum is zero, which can be achieved by reducing the energy quantum size or increasing the energy harvesting capability. Finally, we present several numerical examples to validate the analytical findings.
In this article, a balanced multipath routing and hybrid transmission approach (BMRHTA) is proposed to effectively alleviate the imbalance of the forwarding load in a sink connection area (SCA) and ...prolong the network lifecycle for wireless sensor networks (WSNs). To achieve the energy efficient and balanced WSNs, three design issues, including the multipath, multihop, and single-hop transmissions, are jointly optimized to maximize the overall network lifecycle. First, the path load aggregation phenomenon in the SCA, which makes the forwarding packet load unevenly distributed among hotspots, is examined. In order to achieve the load balance in SCA, multiple shortest balanced paths are generated in the BMRHTA model. In the first stage, two uncorrelated shortest paths are discovered from each node to the sink and the optimal path selection cycle can be determined to achieve the SCA load balance. Afterward, a network equilibrium policy is offered to resolve the optimal transmission period of energy balance via hybrid transmission. As a result, the balanced shortest paths, the path selection cycle and the transmission period can be determined in the network formation phase to avoid the excessive load concentration in the subsequent maintenance phase. Simulation results show that the joint two uncorrelated balanced routing and the proposed network equilibrium policy can nearly quadruple the network lifecycle extension, as compared to a conventional node power policy. Also, the proposed BMRHTA achieves better performance than the current state-of-the-art competitive approaches in terms of energy efficiency and lifecycle.
The island of Taiwan represents an ideal context for studying the effects of climatic oscillations and topographic variation on large herbivores due to its varied tropical to sub-tropical climate ...zones at different elevational ranges. We explored the phylogenetics of Formosan sambar deer (
Rusa unicolor swinhoii
) using the control region of the mitochondrial genome. We detected 18 haplotypes among 454 sequences across the island and grouped them into six regions based on SAMOVA, with 68.78% variance among regions. A Bayesian phylogenetic dendrogram revealed two spatially segregated genetic clades. Neutrality tests and Bayesian skyline plots uncovered different demographic expansion histories for the two clades. We further tested divergence times and chronology to propose potential phylogenetic scenarios, which were examined using approximate Bayesian computation. Finally, we present a credible hypothesis for a glacial refugium in the northern part of the Central Mountain Range. Subsequent secondary contact between the two clades during interglacial periods has led to the extant genetic structure of Formosan sambar deer.
Mesenchymal stem cells (MSCs) have been widely applied to treat various inflammatory diseases. Inflammatory cytokines can induce both apoptosis and autophagy in MSCs. However, whether autophagy plays ...a pro- or con-apoptosis effect on MSCs in an inflammatory microenvironment has not been clarified.
We inhibited autophagy by constructing MSCs with lentivirus containing small hairpin RNA to knockdown Beclin-1 and applied these MSCs to a model of sepsis to evaluate therapeutic effect of MSCs.
Here we show that inhibition of autophagy in MSCs increases the survival rate of septic mice more than control MSCs, and autophagy promotes apoptosis of MSCs during application to septic mice. Further study demonstrated that autophagy aggravated tumor necrosis factor alpha plus interferon gamma-induced apoptosis of MSCs. Mechanically, autophagy inhibits the expression of the pro-survival gene Bcl-2 via suppressing reactive oxygen species/mitogen-activated protein kinase 1/3 pathway.
Our findings indicate that an inflammatory microenvironment-induced autophagy promotes apoptosis of MSCs. Therefore, modulation of autophagy in MSCs would provide a novel approach to improve MSC survival during immunotherapy.
In this paper, we propose an optimal relay transmission policy by using a stochastic energy harvesting (EH) model for the EH two-way relay network, wherein the relay is solar-powered and equipped ...with a finite-sized battery. In this policy, the long-term average outage probability is minimized by adapting the relay transmission power to the wireless channel states, battery energy amount, and causal solar energy states. The designed problem is formulated as a Markov decision process (MDP) framework, and conditional outage probabilities for both decode-and-forward (DF) and amplify-and-forward (AF) cooperation protocols are adopted as the reward functions. We uncover a monotonic and bounded differential structure for the expected total discounted reward, and prove that such an optimal transmission policy has a threshold structure with respect to the battery energy amount in sufficiently high SNRs. Finally, the outage probability performance is analyzed and an interesting saturated structure for the outage performance is revealed, i.e., the expected outage probability converges to the battery empty probability in high SNR regimes, instead of going to zero. Furthermore, we propose a saturation-free condition that can guarantee a zero outage probability in high SNRs. Computer simulations confirm our theoretical analysis and show that our proposed optimal transmission policy outperforms other compared policies.
In this paper, we consider an energy harvesting (EH) two-way (TW) dual-relay network, including one non-EH relay and one EH relay equipped with a finite-sized battery. In the network, a space-time ...transmission protocol with space-time network coding is designed, and an optimal transmission policy for the EH relay is proposed by using a stochastic solar EH model. In this optimal policy, the long-term paired-wise error probability (PEP) of the system is minimized by adapting the EH relay's transmission power to the knowledge of its current battery energy, channel fading status, and causal solar EH information. The designed problem is formulated as a Markov decision process framework, and the conditional capability of the contribution to PEP by the EH relay is adopted as the reward function. We uncover a monotonic and limited difference structure for the expected total discounted reward. Furthermore, a non-conservative property and a monotonic structure of the optimal policy are revealed. Based on the optimal policy and its special structures, the expectation, lower and upper bounds, and asymptotic approximation of the PEP are computed and an interesting result on the system diversity performance is revealed, i.e., the full diversity order can be achieved only if the EH capability index, a metric to quantify the EH node's capability of harvesting and storing energy, approaches to infinity; otherwise, the EH diversity order is only equal to one, and the coding gain of the network is increasing with the EH capability index at this time. Furthermore, a full diversity criterion for the EH TW dual-relay network is proposed. Finally, computer simulations confirm our theoretical analysis and show that our proposed optimal policy outperforms other compared policies.
Recent evidence revealed that glucose fluctuation might be more likely to cause arrhythmia than persistent hyperglycemia, whereas its mechanisms were elusive. We aimed to investigate the effect of ...glucose fluctuation on the occurrence of ventricular arrhythmia and its mechanism.
Streptozotocin (STZ) induced diabetic rats were randomized to five groups: the controlled blood glucose (C-STZ) group, uncontrolled blood glucose (U-STZ) group, fluctuated blood glucose (GF-STZ) group, and GF-STZ rats with 100 mg/kg Tempol (GF-STZ + Tempol) group or with 5 mg/kg KN93 (GF-STZ + KN93) group. Six weeks later, the susceptibility of ventricular arrhythmias and the electrophysiological dysfunctions of ventricular myocytes were evaluated using electrocardiogram and patch-clamp technique, respectively. The levels of reactive oxygen species (ROS) and oxidized CaMKII (ox-CaMKII) were determined by fluorescence assay and Western blot, respectively. Neonatal rat cardiomyocytes and H9C2 cells in vitro were used to explore the underlying mechanisms.
The induction rate of ventricular arrhythmias was 10%, 55%, and 90% in C-STZ group, U-STZ group, and GF-STZ group, respectively (P < 0.05). The electrophysiological dysfunctions of ventricular myocytes, including action potential duration at repolarization of 90% (APD
), APD
short-term variability (APD
-STV), late sodium current (I
), early after depolarization (EAD) and delayed after depolarizations (DAD), as well as the levels of ROS and ox-CaMKII, were significantly increased in GF-STZ group. In vivo and ex vivo, inhibition of ROS or ox-CaMKII reversed these effects. Inhibition of I
also significantly alleviated the electrophysiological dysfunctions. In vitro, inhibition of ROS increase could significantly decrease the ox-CaMKII activation induced by glucose fluctuations.
Glucose fluctuations aggravated the I
induced ventricular arrhythmias though the activation of ROS/CaMKII pathway.
Cardiac resynchronization therapy with or without a defibrillator (CRT(D)) and implantable cardioverter defibrillator (ICD) may reduce the risk of arrhythmia or heart failure‐specific mortality and ...improves the prognosis of patients with chronic kidney disease (CKD) or dialysis. The aim of this study was to perform a meta‐analysis investigating the relationship between CRT(D)/ICD and renal insufficiency. Cochrane Library, Web of Science, Embase, and Pubmed were systematically searched from inception to 29 October 2019. We included studies that report all‐cause mortality of patients with renal insufficiency who received CRT(D)/ICD therapy. Twenty‐six studies (n = 119,263) were included, exploring the relationship between CRT(D)/ICD and renal insufficiency from two aspects: (1) Compared with ICD‐only, CRT(D) was associated with lower risk of all‐cause mortality in CKD patients (odds ratios (OR) = 0.67; 95% confidence interval (CI), 0.60 to 0.75). For non‐primary prevention (secondary prevention or both), the analysis revealed a lower risk of all‐cause mortality in the ICD group than in the no‐ICD group (OR = 0.47; 95% CI, 0.40 to 0.55). (2) CKD increased all‐cause mortality in comparison with control group (OR = 2.12; 95% CI, 1.85 to 2.44), and so did dialysis (OR = 2.53; 95% CI, 2.34 to 2.73). Furthermore, compared with CKD3 (eGFR: 30‐59 ml/min/1.73 m2), CKD4/5 (eGFR <30 ml/min/1.73 m2) was observed to have a significantly higher risk of all‐cause mortality (OR = 2.70; 95% CI, 1.93 to 3.80). This review shows a clear association between CRT(D)/ICD and renal insufficiency in the aspect of all‐cause mortality, and may provide a reference for the clinical application of CRT(D)/ICD.
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