A Numerical Analysis to the {π\pi} and {K} Coupled--Channel Scalar Form-factor

A numerical analysis to the scalar form-factor in the $\pi\pi$ and KK coupled--channel system is made by solving the coupled-channel dispersive integral equations, using the iteration method. The solutions are found not unique. Physical application to the $\pi\pi$ central production in the $pp\to pp\pi\pi$ process is discussed based upon the numerical solutions we found.Comment: 8 pages, Latex, 3 figures. Minor changes and one reference adde

Key values of Chinese consumers buying sustainable goods: the case of Green Food in Fuzhou

This research identifies the key individual values guiding the choice of Chinese customers for Green Food. The work builds on literature on sustainable consumption and the role of values in explaining consumers’ buying behaviour. A questionnaire on values and buying behaviour was administered to customers who buy Green Food in Fuzhou, China. The results indicated that the well-being and health of the respondents and their closest relations were the most important reasons for buying Green Food. Concern for the planet and intergenerational solidarity was less important for most respondents. Lifestyle considerations did not seem to play a role. In the promotion of Green Food the main focus should be on  health benefits; only a limited group will be responsive to arguments in favour of the Earth’s natural environment. The present study was limited to a specific city in China and to buyers of Green Food. Future research should consider replication in other cities and the inclusion of non-buyers. Nevertheless, this study offered some insights into the rapidly expanding market for Green Food in China. In contrast to mature economies such as the European Union and USA, Chinese consumers are more concerned for personal and family health and less for the environment at large. An unexpected result is that buying  motives from existing literature should be reviewed in the light of research on value orientation. Keywords: food consumption, Green Food, sustainable consumption, valuesResearch in Hospitality Management 2012, 1(2): 65–7

Flavonoids activate pregnane × receptor-mediated CYP3A4 gene expression by inhibiting cyclin-dependent kinases in HepG2 liver carcinoma cells

<p>Abstract</p> <p>Background</p> <p>The expression of the drug-metabolizing enzyme cytochrome P450 3A4 (CYP3A4) is regulated by the pregnane × receptor (PXR), which is modulated by numerous signaling pathways, including the cyclin-dependent kinase (Cdk) pathway. Flavonoids, commonly consumed by humans as dietary constituents, have been shown to modulate various signaling pathways (e.g., inhibiting Cdks). Flavonoids have also been shown to induce <it>CYPs </it>expression, but the underlying mechanism of action is unknown. Here, we report the mechanism responsible for flavonoid-mediated PXR activation and <it>CYP </it>expression.</p> <p>Results</p> <p>In a cell-based screen designed to identify compounds that activate PXR-mediated <it>CYP3A4 </it>gene expression in HepG2 human carcinoma cells, we identified several flavonoids, such as luteolin and apigenin, as PXR activators. The flavonoids did not directly bind to PXR, suggesting that an alternative mechanism may be responsible for flavonoid-mediated PXR activation. Consistent with the Cdk5-inhibitory effect of flavonoids, Cdk5 and p35 (a non-cyclin regulatory subunit required to activate Cdk5) were expressed in HepG2. The activation of Cdk5 attenuated PXR-mediated <it>CYP3A4 </it>expression whereas its downregulation enhanced it. The Cdk5-mediated downregulation of <it>CYP3A4 </it>promoter activity was restored by flavonoids, suggesting that flavonoids activate PXR by inactivating Cdk5. <it>In vitro </it>kinase assays showed that Cdk5 directly phosphorylates PXR. The Cdk kinase profiling assay showed that apigenin inhibits multiple Cdks, suggesting that several Cdks may be involved in activation of PXR by flavonoids.</p> <p>Conclusions</p> <p>Our results for the first time link the stimulatory effect of flavonoids on <it>CYP </it>expression to their inhibitory effect on Cdks, through a PXR-mediated mechanism. These results may have important implications on the pharmacokinetics of drugs co-administered with herbal remedy and herbal-drug interactions.</p

Synchronization modulation increases transepithelial potentials in MDCK monolayers through Na/K pumps

Peer reviewedPublisher PD

Enhanced Index-Based Feedback Overhead Reduction for WLANs

Compressed beamforming algorithm is used in the current Wi-Fi standard to reduce the beamforming feedback overhead (BFO). However, with each new amendment of the standard the number of supported antennas in Wi-Fi devices increases, leading to increased BFO and hampering the throughput despite using compressed beamforming. In this paper, a novel index-based method is presented to reduce the BFO in Wi-Fi links. In particular, a k-means clustering-based approach is presented to generate candidate beamforming feedback matrices, thereby reducing the BFO to only the index of the said candidate matrices. With extensive simulation results, we compare the newly proposed method with the IEEE 802.11be baseline and our previously published index-based method. We show approximately 54% gain in throughput at high signal-to-noise (SNR) against the IEEE 802.11be baseline. Our comparison also shows approximately 4 dB gain compared to our previously published method at the packet-error-rate (PER) of 0.01 using MCS index 11. Additionally, we also discuss the impact of the distance metric chosen for clustering as well as candidate selection on the link performance

Binge Alcohol Exposure Causes Neurobehavioral Deficits and GSK3β Activation in the Hippocampus of Adolescent Rats

Heavy alcohol exposure causes profound damage to the adolescent brain, particularly the hippocampus, which underlie some behavioral deficits. However, the underlying molecular mechanisms remain inconclusive. The current study sought to determine whether binge alcohol exposure affects the hippocampus-related behaviors and key signaling proteins that may mediate alcohol neurotoxicity in adolescent rats. Alcohol exposure reduced the number of both NeuN-positive and doublecortin-positive cells in the hippocampus. Alcohol also induced neurodegeneration which was confirmed by ultrastructural analysis by electronic microscopy and was accompanied with the activation of microglia. Binge alcohol exposure impaired spatial learning and memory which was evaluated by the Morris water maze. However, alcohol did not alter the spontaneous locomotor activity which was determined by the open field test. GSK3β is a multi-function serine/threonine protein kinase regulating both neuronal survival and neurogenesis and plays an important role in various neurodegenerative disorders. We have previously shown that GSK3β is a key mediator of alcohol-induced neuron apoptosis in the developing brain. We showed here binge alcohol exposure caused GSK3β activation by inducing dephosphorylation at Ser9 without affecting the phosphorylation of Tyr216 in the hippocampus. Thus, GSK3β may be involved in binge alcohol exposure-induced neuronal damage to the adolescent hippocampus

An Unsupervised Machine Learning Scheme for Index-Based CSI Feedback in Wi-Fi

With the ever-increasing demand for high-speed wireless data transmission, beamforming techniques have been proven to be crucial in improving the data rate and the signal-to-noise ratio (SNR) at the receiver. However, they require feedback mechanisms that need an overhead of information and increase the system complexity, potentially challenging the efficiency and capacity of modern wireless networks. This paper investigates novel index-based feedback mechanisms that aim at reducing the beamforming feedback overhead in Wi-Fi links. The proposed methods mitigate the overhead by generating a set of candidate beamforming vectors using an unsupervised learning-based framework. The amount of feedback information required is thus reduced by using the index of the candidate as feedback instead of transmitting the entire beamforming matrix. We explore several methods that consider different representations of the data in the candidate set. In particular, we propose five different ways to generate and represent the candidate sets that consider the covariance matrices of the channel, serialize the feedback matrix, and account for the effective distance, among others. Additionally, we also discuss the implications of using partial information in the compressed beamforming feedback on the link performance and compare it with the newly proposed index-based methods. Extensive IEEE 802.11 standard-compliant simulation results show that the proposed methods effectively minimize the feedback overhead, enhancing the throughput while maintaining an adequate link performance

Optimal Spatial-Temporal Triangulation for Bearing-Only Cooperative Motion Estimation

Vision-based cooperative motion estimation is an important problem for many multi-robot systems such as cooperative aerial target pursuit. This problem can be formulated as bearing-only cooperative motion estimation, where the visual measurement is modeled as a bearing vector pointing from the camera to the target. The conventional approaches for bearing-only cooperative estimation are mainly based on the framework distributed Kalman filtering (DKF). In this paper, we propose a new optimal bearing-only cooperative estimation algorithm, named spatial-temporal triangulation, based on the method of distributed recursive least squares, which provides a more flexible framework for designing distributed estimators than DKF. The design of the algorithm fully incorporates all the available information and the specific triangulation geometric constraint. As a result, the algorithm has superior estimation performance than the state-of-the-art DKF algorithms in terms of both accuracy and convergence speed as verified by numerical simulation. We rigorously prove the exponential convergence of the proposed algorithm. Moreover, to verify the effectiveness of the proposed algorithm under practical challenging conditions, we develop a vision-based cooperative aerial target pursuit system, which is the first of such fully autonomous systems so far to the best of our knowledge

Spikewhisper: Temporal Spike Backdoor Attacks on Federated Neuromorphic Learning over Low-power Devices

Federated neuromorphic learning (FedNL) leverages event-driven spiking neural networks and federated learning frameworks to effectively execute intelligent analysis tasks over amounts of distributed low-power devices but also perform vulnerability to poisoning attacks. The threat of backdoor attacks on traditional deep neural networks typically comes from time-invariant data. However, in FedNL, unknown threats may be hidden in time-varying spike signals. In this paper, we start to explore a novel vulnerability of FedNL-based systems with the concept of time division multiplexing, termed Spikewhisper, which allows attackers to evade detection as much as possible, as multiple malicious clients can imperceptibly poison with different triggers at different timeslices. In particular, the stealthiness of Spikewhisper is derived from the time-domain divisibility of global triggers, in which each malicious client pastes only one local trigger to a certain timeslice in the neuromorphic sample, and also the polarity and motion of each local trigger can be configured by attackers. Extensive experiments based on two different neuromorphic datasets demonstrate that the attack success rate of Spikewispher is higher than the temporally centralized attacks. Besides, it is validated that the effect of Spikewispher is sensitive to the trigger duration