Classifying human operator functional state based on electrophysiological and performance measures and fuzzy clustering method

The human operator’s ability to perform their tasks can fluctuate over time. Because the cognitive demands of the task can also vary it is possible that the capabilities of the operator are not sufficient to satisfy the job demands. This can lead to serious errors when the operator is overwhelmed by the task demands. Psychophysiological measures, such as heart rate and brain activity, can be used to monitor operator cognitive workload. In this paper, the most influential psychophysiological measures are extracted to characterize Operator Functional State (OFS) in automated tasks under a complex form of human–automation interaction. The fuzzy c-mean (FCM) algorithm is used and tested for its OFS classification performance. The results obtained have shown the feasibility and effectiveness of the FCM algorithm as well as the utility of the selected input features for OFS classification. Besides being able to cope with nonlinearity and fuzzy uncertainty in the psychophysiological data it can provide information about the relative importance of the input features as well as the confidence estimate of the classification results. The OFS pattern classification method developed can be incorporated into an adaptive aiding system in order to enhance the overall performance of a large class of safety–critical human–machine cooperative systems.     

A robust two-gene signature for glioblastoma survival prediction

Glioblastoma multiforme (GBM) is a highly malignant brain tumor. We explored the prognostic gene signature in 443 GBM samples by systematic bioinformatics analysis, using GSE16011 with microarray expression and corresponding clinical data from Gene Expression Omnibus as the training set. Meanwhile, patients from The Chinese Glioma Genome Atlas database (CGGA) were used as the test set and The Cancer Genome Atlas database (TCGA) as the validation set. Through Cox regression analysis, Kaplan-Meier analysis, t-distributed Stochastic Neighbor Embedding algorithm, clustering, and receiver operating characteristic analysis, a two-gene signature (GRIA2 and RYR3) associated with survival was selected in the GSE16011 dataset. The GRIA2-RYR3 signature divided patients into two risk groups with significantly different survival in the GSE16011 dataset (median: 0.72, 95% confidence interval [CI]: 0.64-0.98, vs median: 0.98, 95% CI: 0.65-1.61 years, logrank test P < .001), the CGGA dataset (median: 0.84, 95% CI: 0.70-1.18, vs median: 1.21, 95% CI: 0.95-2.94 years, logrank test P = .0017), and the TCGA dataset (median: 1.03, 95% CI: 0.86-1.24, vs median: 1.23, 95% CI: 1.04-1.85 years, logrank test P = .0064), validating the predictive value of the signature. And the survival predictive potency of the signature was independent from clinicopathological prognostic features in multivariable Cox analysis. We found that after transfection of U87 cells with small interfering RNA, GRIA2 and RYR3 influenced the biological behaviors of proliferation, migration, and invasion of glioblastoma cells. In conclusion, the two-gene signature was a robust prognostic model to predict GBM survival.     

Store-Operated Ca2+ Channels Blockers Inhibit Lipopolysaccharide Induced Astrocyte Activation

The destruction of calcium homeostasis is an important factor leading to neurological diseases. Store-operated Ca²⁺ (SOC) channels are essential for Ca²⁺ homeostasis in many cell types. However, whether SOC channels are involved in astrocyte activation induced by lipopolysaccharide (LPS) still remains unknown. In this study, we used LPS as an exogenous stimulation to investigate the role of SOC channels in astrocyte activation. Using calcium imaging technology, we first found that SOC channels blockers, 1-[h-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole (SKF-96365) and 2-aminoethyldiphenyl borate (2-APB), inhibited LPS induced [Ca²⁺]_i increase, which prompted us to speculate that SOC channels may be involved in LPS induced astrocyte activation. Further experiments confirmed our speculation shown as SOC channels blockers inhibited LPS induced astrocyte activation characterized as cell proliferation by MTS and BrdU assay, raise in glial fibrillary acidic protein expression by immunofluorescence and Western Blot and secretion of interleukin 6 (IL-6) and interleukin 1β (IL-1β) by ELISA. So, our studies showed that SOC channels are involved in LPS-induced astrocyte activation.     

The Possible Structural Models for Polyglutamine Aggregation: A Molecular Dynamics Simulations Study

Abstract

Huntington's disease is a neurodegenerative disorder caused by a polyglutamine (polyQ) expansion near the N-terminus of huntingtin. Previous studies have suggested that polyQ aggregation occurs only when the number of glutamine (Q) residues is more than 36-40, the disease threshold. However, the structural characteristics of polyQ nucleation in the very early stage of aggregation still remain elusive. In this study, we designed 18 simulation trials to determine the possible structural models for polyQ nucleation and aggregation with various shapes and sizes of initial β-helical structures, such as left-handed circular, right-handed rectangular, and left- and right-handed triangular. Our results show that the stability of these models significantly increases with increasing the number of rungs, while it is rather insensitive to the number of Qs in each rung. In particular, the 3-rung β-helical models are stable when they adopt the left-handed triangular and right-handed rectangular conformations due to the fact that they preserve high β-turn and β-sheet contents, respectively, during the simulation courses. Thus, we suggested that these two stable β-helical structures with at least 3 rungs might serve as the possible nucleation seeds for polyQ depending on how the structural elements of β-turn and β-sheet are sampled and preserved during the very early stage of aggregation.     

Structure of the Type VI Effector-Immunity Complex (Tae4-Tai4) Provides Novel Insights into the Inhibition Mechanism of the Effector by Its Immunity Protein

The type VI secretion system (T6SS), a multisubunit needle-like apparatus, has recently been found to play a role in interspecies interactions. The Gram-negative bacteria harboring T6SS (donor) deliver the effectors into their neighboring cells (recipient) to kill them. Meanwhile, the cognate immunity proteins were employed to protect the donor cells against the toxic effectors. Tae4 (type VI amidase effector 4) and Tai4 (type VI amidase immunity 4) are newly identified T6SS effector-immunity pairs. Here, we report the crystal structures of Tae4 from Enterobacter cloacae and Tae4-Tai4 complexes from both E. cloacae and Salmonella typhimurium. Tae4 acts as a dl-endopeptidase and displays a typical N1pC/P60 domain. Unlike Tsi1 (type VI secretion immunity 1), Tai4 is an all-helical protein and forms a dimer in solution. The small angle x-ray scattering study combined with the analytical ultracentrifugation reveal that the Tae4-Tai4 complex is a compact heterotetramer that consists of a Tai4 dimer and two Tae4 molecules in solution. Structure-based mutational analysis of the Tae4-Tai4 interface shows that a helix (α3) of one subunit in dimeric Tai4 plays a major role in binding of Tae4, whereas a protruding loop (L4) in the other subunit is mainly responsible for inhibiting Tae4 activity. The inhibition process requires collaboration between the Tai4 dimer. These results reveal a novel and unique inhibition mechanism in effector-immunity pairs and suggest a new strategy to develop antipathogen drugs.     

藏鹀的自然历史、威胁和保护

藏鹀(Emberiza koslowi)是我国青藏高原东部的特有珍稀鸟种,目前关于它的资料非常匮乏.为了解藏鹀的分布、数量和基本生活史特征,促进对于该物种的有效保护,自2005年起以青海省果洛州久治县白玉乡为中心对藏鹀进行了持续6年的观察,并针对其面临的威胁采取了相应的保护措施.结果显示,藏鹀主要分布在青海的玉树、果洛和四川的阿坝一带海拔3 500～4 700 m范围内的适宜栖息地,该分布区比原有认知更靠东北,更为狭小且海拔更高.用样线法开展的藏鹀数量监测,在7.4 km2的调查范围内记录到一个18 ～33只的稳定种群.此外,还对藏鹀的筑巢、育雏和争斗等行为进行了详细描述.食肉动物的捕食、冬季食物缺乏和牲畜踩踏鸟卵是藏鹀面临的最直接威胁.通过持续监测、与当地牧民协商、建立保护小区并开展有针对性的保护,藏鹀种群趋于稳定.     

Synthesis and antibacterial activity of 9-oxime ether non-ketolides,and novel binding mode of alkylides with bacterial rRNA

We report a series of new 9-oxime ether non-ketolides, including 3-hydroxyl, 3-O-acyl and 3-O-alkyl clarithromycin derivatives, and thiophene-containing ketolides 1b–1d. Unlike previously reported ketolide 1a, none of them is comparable to telithromycin. A molecular modeling study was performed to gain insight into the binding mode of alkylides 17–20 with bacterial rRNA and to rationalize the great disparity of their SAR. The 3-O-sidechains of 19 and 20 point to the so-called hydrophilic side of the macrolide ring, as seen in clarithromycin. In contrast, the 3-O-sidechains of 17 and 18 bend to the backside, the so-called hydrophobic side of the macrolide ring. The results clearly indicated the alkylides with improved antibacterial activity might possess a novel binding mode, which is different from clarithromycin and the alkylides with poor activity.     

农地保护的外部效益测算——选择实验法在武汉市的应用

农地保护的外部效益是农地保护补偿政策制定的依据.对外部效益进行了理论界定和实证测算,认为农地保护的外部效益是农村集体和农地使用者以外个体从农地保护中得到的收益,通常是非市场收益,对其测算应区分外部效益的内部(外部效益发出者)和外部(外部效益接受者),并确定外部区域的范围.实证利用选择实验模型对武汉市5个区域进行了支付意愿测算,在内外部划分的基础上估算了武汉市农地保护的外部效益并比较了不同方法下外部效益测算结果的差别.结果表明,武汉市耕地、园地、林地和农村水面的外部效益分别为30773.2,653860.0,119267.0和82472.7元/hm2;用行政区域直接代替外部性影响区域的做法会使耕地外部效益的测算结果偏高,也会造成园地、林地和农村水面测算的误差,为避免这类误差,外部性测算及相关补偿、税费政策应考虑内外部区域的划分.     

基于高分辨率遥感影像的森林地上生物量估算

以南京市紫金山林区为研究区,利用e-Cognition面向对象分类方法,基于光谱和空间信息融合后的IKONOS影像提取单木树冠阳性冠幅(PoCA, Positive crown area)信息,并结合野外实测的样方生物量数据,分别建立了针叶林和阔叶林地上生物量 (AGB, Aboveground Biomass)的遥感估算模型,并利用实测森林生物量数据对模型进行了验证。结果表明,基于遥感影像提取的PoCA与实测AGB存在较好的非线性相关关系,所建针叶林AGB估算模型的可靠性优于阔叶林模型。对建模样本而言,估算的针叶林和阔叶林AGB与观测数据比较的R2分别为0.62 (P<0.01,n=9) 和0.56(P<0.01,n=16)。验证表明,所建AGB估算模型的可靠性较好,估算的针叶林和阔叶林AGB与观测数据比较的R2分别为0.55(P<0.01,n=6) 和0.52(P<0.01,n=10),但当AGB较低时,模型结果偏高,AGB较低时,模型结果偏低。研究说明通过高分辨率遥感数据的融合、提取树冠信息进行生物量估算是可行性的。