mlsa-iai-msu-lab/ru_sci_bench_zho_cite_reranking huggingface dataset:
Arctic Oscillation Responses to Black Carbon Aerosols Emitted from Major Regions

The responses of the Arctic Oscillation (AO) to global black carbon (BC) and BC emitted from major regions were compared using the atmospheric general circulation model Geophysical Fluid Dynamics Laboratory (GFDL) atmospheric general circulation model (AGCM) Atmospheric Model version 2.1 (AM2.1). The results indicated that global BC could induce positive- phase AO responses, characterized by negative responses over the polar cap on 500 hPa height fields, and zonal mean sea level pressure (SLP) decreasing while zonal wind increasing at 60°, with the opposite responses over midlatitudes. The AO indices distribution also shifted towards positive values. East Asian BC had similar impacts to that of global BC, while the responses to European BC were of opposite sign. South Asian BC and North American BC did not affect the AO significantly. Based on a simple linear assumption, we roughly estimated that the global BC emission increase could explain approximately 5% of the observed positive AO trend of +0.32 per decade during 1960 to 2000.
Response of Lakes to Climate Change in Xainza Basin Tibetan Plateau Using Multi-Mission Satellite Data from 1976 to 2008

Changes in the lake areas of Xainza basin in the past 33 years (1976 to 2008) were studied using Landsat data from Multispectral Scanners (1973- 1977), Thematic Mapper (1989-1992, 2007-2009), and Enhanced Thematic Mapper Plus (1999-2002). The results indicated that lakes in the study area evidently expanded from 1976 to 2008, with total expansion of 1512.64 km~2. The mean annual air temperature presented an upward trend with certain fluctuations from 1966 to 2008. The air temperature rise rates in the cold season (0.31℃/10a) were higher than those in the hot season (0.24℃/10a), in the Xainza station example. Precipitation exhibited evident seasonal differences. Mean annual precipitation in hot season is 281.48 mm and cold season is 32.66 mm from 1966 to 2008 in study area. Precipitation in the hot season was the major contributor to the increase in annual precipitation. Grey relational analysis (GRA) was used to study the response of lake areas to climatic factors. The mean air temperature and precipitation were selected as compared series, and the lake areas were regarded as the reference series. The grey relational grade (GRG) between compared series and reference series were calculated through GRA. The results indicated that changes in lake areas were mainly affected by climatic factors in the hot season. Lakes in this region were classified into three grades, namely, Grades I, II, and III according to the recharge source and elevation. The GRGs of each series varied for different grade lakes: the area of Grade III lakes were the most relevant to the hot season factors, the GRGs of precipitation and air temperature were 0.7570 and 0.6606; followed by the Grade II lakes; Grade I lakes were more sensitive to the air temperature.
Feature Selection and Feature Learning for High-dimensional Batch Reinforcement Learning: A Survey

Tremendous amount of data are being generated and saved in many complex engineering and social systems every day. It is significant and feasible to utilize the big data to make better decisions by machine learning techniques. In this paper, we focus on batch reinforcement learning (RL) algorithms for discounted Markov decision processes (MDPs) with large discrete or continuous state spaces, aiming to learn the best possible policy given a fixed amount of training data. The batch RL algorithms with handcrafted feature representations work well for low-dimensional MDPs. However, for many real-world RL tasks which often involve high-dimensional state spaces, it is difficult and even infeasible to use feature engineering methods to design features for value function approximation. To cope with high-dimensional RL problems, the desire to obtain data-driven features has led to a lot of works in incorporating feature selection and feature learning into traditional batch RL algorithms. In this paper, we provide a comprehensive survey on automatic feature selection and unsupervised feature learning for high-dimensional batch RL. Moreover, we present recent theoretical developments on applying statistical learning to establish finite-sample error bounds for batch RL algorithms based on weighted L_p norms. Finally, we derive some future directions in the research of RL algorithms, theories and applications.
双胞胎兄弟同患脊髓空洞症并夏科关节病

脊髓空洞症(syringomyelia,SM)最初于1872年由Ollivier d'Angers提出,是一种脊髓的退行性疾病,其确切病因及发病机制至今尚无统一认识。临床上常见颅颈交界区的先天性畸形尤其是小脑扁桃体下疝畸形最为常见,空洞多形成于颈段和上胸段脊髓内,可能与畸形导致该部位脑脊液循环不畅有关,从而脊髓出现损伤而形成空洞。除此之外,脊髓肿瘤、损伤及神经系统感染等因素均可引起脊髓空洞形成。
高龄患者冠状动脉旁路移植术的围手术期疗效分析

目的总结75岁以上高龄冠心病患者行冠状动脉旁路移植术(CABG)的围手术期临床经验,以提高手术疗效。方法2014年2 ~ 6月沈阳军区总医院心外科为20例75 ~ 84岁冠状动脉粥样硬化患者行非体外循环冠状动脉旁路移植术,其中男11例、女9例,主要病变均为三支冠状动脉严重狭窄或伴左主干狭窄,其中5例患者伴急性心肌梗死,所有患者均为限期手术。分析全组手术时间、住院时间、围手术期并发症、术后结果等。结果全组均采用左乳内动脉吻合前降支,大隐静脉吻合其他分支,平均桥血管数量为3.2支;平均手术时间3.3 h;术后平均呼吸机辅助时间9.6 h;术后平均重症监护时间26.4 h;术后平均住院时间为12.3 d。术后出现阵发性心房颤动3例;术后呼吸机辅助期间低氧血症2例,术后因咳痰无力及误吸并发严重肺炎1例;术后明显腹胀、纳差6例,其中1例因腹胀行短期胃肠减压及完全胃肠道外营养,1例因纳差再次入院治疗;术后伤口愈合不良清创缝合1例。所有患者均痊愈出院,心功能改善,心绞痛症状消失。结论对于高龄患者,非体外循环冠状动脉旁路移植术疗效满意;胃肠功能、呼吸功能及手术耐受力为影响高龄患者围手术期恢复较为突出的因素,应采取更为积极的治疗和应对策略。
短暂性全面遗忘症27例临床分析

短暂性全面遗忘症(TGA)以突发的顺行性遗忘为特征,无其他神经系统阳性体征,症状常在24 h内缓解。临床上较为少见,本文回顾性分析我院收治的TGA患者的临床资料。
过氧化物酶增殖物激活受体δ对糖脂代谢的影响

过氧化物酶增殖物激活受体(PPARs)是核受体超家族的成员之一,发现于1990年,迄今为止已确定3个亚型:PPARα、PPARβ/δ和PPARγ。其中PPARδ在糖脂代谢、转运和胰岛素敏感性方面发挥重要的调节作用。PPARδ的活化不仅可以减轻肥胖、改善胰岛素抵抗(IR),还可促进巨噬细胞胆固醇代谢,抑制炎症介质表达而减缓动脉粥样硬化的进程。本文就PPARδ对糖脂代谢和老年相关性疾病的影响作一综述。
超声在老年人颈性眩晕临床诊断中的价值

目的探讨彩色超声多普勒检查在诊断老年人颈性眩晕中的临床应用价值。方法选取来该院就诊的老年颈性眩晕患者72例为观察组,同时随机选取同期在我院体检的健康老年受试者72例为对照组。采用彩色超声多普勒检查评估两组受试者的椎动脉,统计观察组患者椎动脉异常的情况,对比两组受试者椎动脉内径以及血流的参数。结果观察组72例患者中,64例(88.89%)发现血管存在狭窄,其中椎动脉发现狭窄最常见,占56.94%(41例),小脑前下动脉和小脑后上动脉狭窄分别占19.44%(14例)和12.50%(9例)。观察组的左侧椎动脉内径为(3.28±0.31)mm,右侧椎动脉内径为(3.18±0.15)mm,左侧峰值流速为(39.62±4.85)cm/s,右侧峰值流速为(39.13±5.42)cm/s,左侧血流量为(131.63±17.95)ml/min,右侧血流量为(116.12±17.83)ml/min,总血流量为(245.73±17.36)ml/min,均显著低于对照组(均P<0.05)。结论超声检查是一种无创的评价椎动脉病变和血流动力学改变的检查手段,可以为老年颈性眩晕的诊断提供重要的参考信息。
噻托溴铵治疗重度支气管哮喘的疗效及对血清TNF-α和IL-6水平的影响

目的探讨噻托溴铵治疗高龄重度支气管哮喘的疗效及其对患者血清肿瘤坏死因子(TNF)-α和白细胞介素(IL)-6影响。方法在该院接受治疗的高龄重度支气管哮喘患者106例,随机分成对照组和观察组各53例。对照组患者接受重度支气管哮喘的常规治疗。观察组在常规治疗方式的基础上,同时联合应用噻托溴铵吸入治疗。结果观察组患者的总有效率高于对照组(P<0.01)。治疗后,观察组患者TNF-α和IL-6水平低于对照组(P<0.01),肺功能指标用力肺活量(FVC)、最大呼吸峰值(PEF)以及第1秒肺呼吸量百分比(FEV_1%)水平高于对照组(P<0.01),治疗后,免疫球蛋白IgA、IgM以及IgG水平高于对照组(P<0.01),生活质量高于对照组(P<0.01)。结论噻托溴铵治疗高龄重度支气管哮喘疗效显著,能够减轻患者炎症反应,改善患者肺功能,调节患者免疫功能,提高患者生活质量。
脑卒中后2 w抑郁障碍对脑卒中复发的影响

目的探讨脑卒中后2 w抑郁障碍(PSD)对脑卒中复发的影响以及危险因素。方法随机选取该院2012年2月至2013年2月神经内科诊断的脑卒中患者72例,对其临床资料进行回顾性分析。结果随访信息完整者60例(83.33%),其中发生PSD患者38例(63.33%),未发生PSD患者22例(36.67%);发生PSD患者中出现脑卒中复发者7例(18.42%),明显高于未发生PSD患者中出现脑卒中复发者2例(9.09%)(χ~2=5.536,P=0.019)。与未发生PSD患者比较,PSD患者中女性、心脏病史、抗抑郁药比例更高,年龄更大,入院首次脑卒中评分更高(P<0.05)。多因素Logistic回归分析显示,患者的年龄(OR=1.667,P=0.007)、入院首次脑卒中评分(OR=0.981,P=0.022)、心脏病史(OR=1.071,P=0.014)均是PSD患者发生脑卒中复发的独立危险因素。结论脑卒中后2 w发生PSD会明显增加脑卒中的复发率,其中年龄、心脏病史、入院首次脑卒中评分是脑卒中2 w PSD患者脑卒中复发的独立危险因素,合理纠正这些危险因素带来的影响,将有助于预防脑卒中复发。
Protection Methods to Reduce Nitrogen and Phosphorus Losses from Sloping Citrus Land in the Three Gorges Area of China

The increased application of chemical fertilizers in citrus orchards and the non-point source nitrogen (N) and phosphorus (P) diffusion threaten the fresh water quality of the Three Gorges Reservoir area of China. A 10-year field trial on sloping citrus lands was conducted to evaluate five protection methods for reducing N and P losses: 1) intercropping with perennial white clover (CW); 2) straw mulching of the soil surface (CS); 3) intercropping with yellow daylily contour hedgerows (CH); 4) an impermeable membrane buried in the soil along the contour lines (CM); and 5) intercropping with a rotation of wheat and peanut (CWP). An area of conventional citrus management was also maintained as the control (CK). The results showed that CM and CH were the most effective methods for reducing surface runoff. The sediment yield were reduced at the highest rate by CW and CH and was also significantly reduced by CS. Reduced runoff volume and sediment yield were the crucial mechanism for the reductions in N and P losses. Compared with the control, CW, CS, CH, and CM reduced annual runoff by 9%, 13%, 25%, and 30%, sediment yield by 77%, 55%, 71%, and 28%, N loss by 10%, 23% 36%, and 37%, and P loss by 39%, 31%, 27%, and 25%, respectively. CW, CS, CH, and CM were effective in reducing N and P losses from the sloping citrus land. However, over the long-term, surface soil nutrient accumulation in CW, CS, and CH diminished the benefit of those methods in reducing N and P losses. In addition, CWP increased soil erosion and nutrient loss, which showed that citrus intercropping with other crops was an unsuitable method for citrus sloping land in the Three Gorges area.
UV/Vis Characterization and Fate of Organic Amendment Fractions in a Dune Soil in Dakar, Senegal

The application of organic amendments on soils poor in organic matter (OM) can improve long-term soil fertility, but may also enhance the mineralization of native soil organic matter. Three organic amendments, compost, sewage sludge and horse manure, used by urban market gardeners in Dakar, Senegal were analyzed for their OM maturity. Their fate was evaluated in a 45-d agronomic trial in a sandy Arenosol with lettuce. In each case, water-extractable organic matter (WEOM) and humic-like substances (HLS) were isolated from raw amendments and amended soils, and characterized using ultraviolet-visible (UV/Vis) spectroscopy. Results highlighted the general more aromatic character of HLS and WEOM fractions extracted from compost compared to the other two amendments. When applied to soils, however, these differences were not clearly observed. The aromaticity and humification degree of the labile fraction (WEOM) increased with depth in the first 30 cm for all amendments. This indicated the high lixiviation rates that fresh OM underwent in the studied sandy soil. Finally, a statistical analysis of the results was able to discriminate between surface and deeper horizons and between amended- and non-amended soil samples. Spectroscopic indices showed indeed strong increase/decrease with depth linked with the mineralization/humification processes that the fresh OM from amendments underwent during the 45 d of the agronomic trial. This study highlights the potential of spectroscopic techniques to study agricultural amendment organic matter fractions and their fate in soils.
Impact of Wetland Change on Local Climate in Semi-arid Zone of Northeast China

Wetlands are sensitive to climate change, in the same time, wetlands can influence climate. This study analyzed the spatio- temporal characteristics of wetland change in the semi-arid zone of Northeast China from 1985 to 2010, and investigated the impact of large area of wetland change on local climate. Results showed that the total area of wetlands was on a rise in the study area. Although natural wetlands (marshes, riparians and lakes) decreased, constructed wetlands (rice fields) increased significantly, and the highest increase rate in many places exceeded 30%. Anthropogenic activities are major driving factors for wetland change. Wetland change produced an impact on local climate, mainly on maximum temperature and precipitation during the period of May–September. The increase (or decrease) of wetland area could reduce (or increase) the increment of maximum temperature and the decrement of precipitation. The changes in both maximum temperature and precipitation corresponded with wetland change in spatial distribution. Wetland change played a more important role in moderating local climate compared to the contribution of woodland and grassland changes in the study area. Cold-humid effect of wetlands was main way to moderating local climate as well as alleviating climatic warming and drying in the study area, and heterogeneity of underlying surface broadened the cold-humid effect of wetlands.
Effects of Long-Term Groundwater Management and Straw Application on Aggregation of Paddy Soils in Subtropical China

Soil organic carbon (SOC) and iron (Fe)-oxides are important contributors of aggregate stability in highly weathered soils, and they are influenced by groundwater management and straw application. A 30-year plot experiment with early rice (Oryza sativa L.)-late rice-winter fallow rotations was conducted using a upland clay soil in cement pools under shallow groundwater table at a depth of 20 cm (SGT) and deep groundwater table at a depth of 80 cm (DGT) to simulate the groundwater tables of two types of important paddy soils, gleyed paddy soils and hydromorphic paddy soils, respectively, in subtropical China. Soil redox potential(Eh) was measured in situ, and 0–20 cm soil samples were collected for the analyses of soil Fe-oxides, SOC, and aggregates under SGT or DGT with different straw application treatments, in order to evaluate the interaction of groundwater management and straw application on paddy soil aggregation and the relative importance of SOC or Fe-oxides on soil aggregation. The results showed that soil Eh was restricted by irrigation, and its variation was more significant under DGT than under SGT. The decreased soil Eh or reduced drying and wetting cycles under SGT resulted in more SOC accumulation with the straw application, had no effect on soil free Fe-oxides (Fed), significantly increased the amorphous Fe-oxide (Feo) and complex Fe-oxide contents, but decreased the crystalline Fe-oxide content (Fed–Feo). The soils under DGT had more macroaggregates than those under SGT, but the difference decreased with the straw application. It could be concluded that soil Fe-oxides were the principal contributing factor to the aggregation of paddy soils in subtropical China and SOC was also an important contributing factor.
Profile of Implanon~? acceptors and pattern of side effects

Objective To determine the social and biological characteristics of Implanon~? acceptors at Ibadan Nigeria, and also to describe reasons why they opt for this choice and their concerns. Methods This was a descriptive study that retrospectively reviewed all records of the Implanon~? acceptors from January 2006 to December 2009 at University College Hospital, Ibadan, Nigeria. Results One hundred and twenty-eight women accepted Implanon~? as a modern contraception accounting 4.3% of the total number of clients seen (2 972) during the period. The age range of the client that accepted Implanon~? was 26-43 years with a mean of 33.6 ± 2.4 years. Of the 128 Implanon~? acceptors, 101 (78.9%) had used other contraceptive methods before. The commonest reason for switching to Implanon~? by clients was failure of the contraceptive method that was previously used (32.7%). Within the first year follow-up of insertion, none of the Implanon~? acceptors had expressed desire for removal due to any of the side effects, and none contraceptive failure was observed during their follow-up evaluation. Conclusion The findings suggest that Implanon~? could safely be used by all women of reproductive age group including those who desire future fertility.
Deficient plastidic fatty acid synthesis triggers cell death by modulating mitochondrial reactive oxygen species

Programmed cell death (PCD) is of fundamental importance to development and defense in animals and plants. In plants, a well-recognized form of PCD is hypersensitive response (HR) triggered by pathogens, which involves the generation of reactive oxygen species (ROS) and other signaling molecules. While the mitochondrion is a master regulator of PCD in animals, the chloroplast is known to regulate PCD in plants. Arabidopsis Mosaic Death 1 (MOD1), an enoyl-acyl carrier protein (ACP) reductase essential for fatty acid biosynthesis in chloroplasts, negatively regulates PCD in Arabidopsis. Here we report that PCD in mod1 results from accumulated ROS and can be suppressed by mutations in mitochondrial complex I components, and that the suppression is confirmed by pharmaceutical inhibition of the complex I-generated ROS. We further show that intact mitochondria are required for full HR and optimum disease resistance to the Pseudomonas syringae bacteria. These findings strongly indicate that the ROS generated in the electron transport chain in mitochondria plays a key role in triggering plant PCD and highlight an important role of the communication between chloroplast and mitochondrion in the control of PCD in plants.
中国2004年以来精神卫生服务的发展与问题

随着经济的发展和人民生活水平的提高,群众对改善医药卫生服务的要求也越来越高。工业化、城镇化、人口老龄化、疾病谱变化和生态环境变化等,都给医药卫生工作带来一系列新的严峻挑战。深化医药卫生体制改革,是加快医药卫生事业发展的战略选择,是实现人民共享改革发展成果的重要途径,是广大人民群众的迫切愿望。作为医药卫生的重要组成部分,精神卫生服务自2004年来取得较快速发展。在“新常态”(new normal)下,充满新矛盾、新问题、新风险、新机遇,总结十年来精神卫生服务发展的得与失,为今后发展提供新的思路。
Array-CGH联合NIPT进行染色体微缺失和重复产前检测的应用价值

目的探讨无创产前检测技术(noninvasive prenatal testing,NIPT)联合基于微阵列芯片的比较基因杂交技术(array-based comparative genomic hybridization,Array-CGH)在染色体微缺失或重复中的产前检测价值。方法选择孕12~24周高危孕妇,采集静脉血并提取循环胎儿游离DNA(cell-free fetal DNA,cffDNA),利用NIPT技术检测,结果为阳性者,适时进行羊膜腔或脐静脉穿刺并以Array-CGH技术检测,以DECIPHER和OMIM数据库对检测数据进行分析,所有病例随访至胎儿出生。结果NIPT检出10例阳性,Array-CGH检测和随访证实其中6例为染色体缺失或重复,但所检出的缺失或重复以及片段长度与NIPT不一样;4例Chr7长臂偏多为假阳性。另1例NIPT结果阴性但Array-CGH发现异常。结论 Array-CGH联合NIPT进行胎儿染色体微缺失和重复产前检测具有重要临床应用价值。
基于TM遥感影像数据的乌鲁木齐热岛效应分析

近年来,随着城市的飞速发展,热岛效应也颇受人们重视。本文采用1990年和2010年的TM遥感影像,运用亮度温度计算和二分模型计算等方法,并结合亮度温度数据得到了植被覆盖度对城市亮度温度的影响和土地利用对亮度温度的影响,分析了造成乌鲁木齐市城市热岛空间分布的原因。结果显示,热岛中心主要分布在城区人口密度大及工业区聚集的地方,植被和水体对减弱热岛效应起到一定作用。
各组合模型在GPS高程拟合中的应用研究

针对单一模型自身存在的局限性,提出了最优非负变权GPS高程拟合模型。该模型以最小二乘拟合估计、主成分估计、半参数估计3种单一模型的预测结果为组合预测值,以预测误差平方和最小为目标,通过规划法求解变权系数,并与最优加权组合模型、BP神经网络组合模型进行了对比。结果表明,最优非负变权组合模型能有效综合单一模型的优点,利用动态的权值进行预测,综合精度较高,能够提供更准确的结果,在GPS高程拟合中的应用是可行的。
The physiological role of drug transporters

Transporters comprise the largest family of membraneproteins in human organism, including members of solutecarrier transporter and ATP-binding cassette transporterfamilies. They play pivotal roles in the absorption,distribution and excretion of xenobiotic and endogenousmolecules. Transporters are widely expressed in varioushuman tissues and are routinely evaluated during theprocess of drug development and approval. Over the pastdecade, increasing evidence shows that drug transportersare important in both normal physiology anddisease. Currently, transporters are utilized as therapeutictargets to treat numerous diseases such as diabetes,major depression, hypertension and constipation. Despitethe steady growth of the field of transporter biology,more than half of the members in transporter superfamilyhave little information available about their endogenoussubstrate(s) or physiological functions. This review outlinescurrent research methods in transporter studies,and summarizes the drug-transporter interactions includingdrug-drug and drug-endogenous substrate interactions.In the end, we also discuss the therapeuticperspective of transporters based on their physiologicaland pathophysiological roles.
Contrasting dynamic characteristics of shear turbulence and Langmuir circulation in the surface mixed layer

Large eddy simulation (LES) is used to investigate contrasting dynamic characteristics of shear turbulence (ST) and Langmuir circulation (LC) in the surface mixed layer (SML). ST is usually induced by wind forcing in SML. LC can be driven by wave-current interaction that includes the roles of wind, wave and vortex forcing. The LES results show that LC suppresses the horizontal velocity and greatly modifies the downwind velocity profile, but increases the vertical velocity. The strong downwelling jets of LC accelerate and increase the downward transport of energy as compared to ST. The vertical eddy viscosity K_m of LC is much larger than that of ST. Strong mixing induced by LC has two locations. They are located in the 2δ_s–3δ_s (Stokes depth scale) and the lower layer of the SML, respectively. Its value and position change periodically with time. In contrast, maximum K_m induced by ST is located in the middle depth of the SML. The turbulent kinetic energy (TKE) generated by LC is larger than that by ST. The differences in vertical distributions of TKE and K_m are evident. Therefore, the parameterization of LC cannot be solely based on TKE. For deep SML, the convection of large-scale eddies in LC plays a main role in downward transport of energy and LC can induce stronger velocity shear (S~2) near the SML base. In addition, the large-scale eddies and S~2 induced by LC is changing all the time, which needs to be fully considered in the parameterization of LC.
Seasonal variability of the Kuroshio Current at the PN Section in the East China Sea based on in-situ observation from 1987 to 2010

As the spatio-temporal variability of the Kuroshio is highly influenced by mesoscale eddies, representing its seasonal variability characteristics requires sufficiently long term observations to reduce the uncertainties. Geostrophic velocity data estimated from hydrographic observation from 1987 to 2010 and the shipboard ADCP velocity data from 1993 to 2008 at the PN Section in the central East China Sea are collected to view the seasonal variability objectively. From both types of observation, it is found that the seasonal climatology mean of the Kuroshio Current exhibits significant difference in three areas, which are located at the Kuroshio Current core and its two flanks in a shallow layer less than 300 m, with the weakest northeast current at the core in autumn, the strongest counter current on the right flank in spring, and the strongest northeast current on the left flank in autumn, respectively. The seasonal variance of the Kuroshio Current also exhibits significant difference on the offshore side of the Kuroshio, with larger variance in spring and summer while smaller variance in autumn and winter. For the current parallel to the PN Section, the ratio of the seasonal variability component to the intraseasonal variability component is relatively smaller than that for the current perpendicular to the PN Section. Further analyses indicate that the seasonal variability at the PN Section is tightly linked to the upstream and downstream current variability.
Effects of exotic and endogenous shrubs on understory vegetation and soil nutrients in the south of Tunisia

This study was conducted in southern Tunisia in the growing seasons of 2013 and 2014, and aimed to compare the effects of exotic and endogenous shrub species (Haloxylon persicum and Retama raetam, respectively) on understory vegetation and soil nutrients. For each shrub species, the canopied sub-habitat (under the shrub crown) and un-canopied sub-habitat (in open grassland area) were distinguished. The concentrations of soil nutrients (organic matter, total nitrogen and extractable phosphorus) were found to be significantly higher (P<0.05) under R. raetam canopy than under H. persicum canopy and in open area. The result also showed that the presence of shrubs improved all the values of understory vegetation parameters (floristic composition, density, total plant cover and dry matter) and all these values were significantly higher under endogenous species canopy than under exotic species canopy. These results highlighted the positive effect of endogenous shrubs on understory vegetation and soil nutrients compared to the exotic ones in the Saharan areas of Tunisia.
Asymmetric resistive switching processes in W:AlO_x/WO_y bilayer devices

Asymmetric resistive switching processes were observed in W:AlO_x/WO_y bilayer RRAM devices. During pulse programming measurements, the RESET speed is in the range of hundreds of microseconds under -1.1 V bias, while the SET speed is in the range of tens of nanoseconds under 1.2 V bias. Electrical measurements with different pulse conditions and different temperatures were carried out to understand these significant differences in switching time. A redox reaction model in the W:AlO_x/WO_y device structure is proposed to explain this switching time difference.