Grouping tree species to estimate basal area increment in temperate multispecies forests in Durango,Mexico

Multispecies forests have received increased scientific attention,driven by the hypothesis that biodiversity improves ecological resilience.However,a greater species diversity presents challenges for forest management and research.Our study aims to develop basal area growth models for tree species cohorts.The analysis is based on a dataset of 423 permanent plots(2,500 m^(2))located in temperate forests in Durango,Mexico.First,we define tree species cohorts based on individual and neighborhood-based variables using a combination of principal component and cluster analyses.Then,we estimate the basal area increment of each cohort through the generalized additive model to describe the effect of tree size,competition,stand density and site quality.The principal component and cluster analyses assign a total of 37 tree species to eight cohorts that differed primarily with regard to the distribution of tree size and vertical position within the community.The generalized additive models provide satisfactory estimates of tree growth for the species cohorts,explaining between 19 and 53 percent of the total variation of basal area increment,and highlight the following results:i)most cohorts show a"rise-and-fall"effect of tree size on tree growth;ii)surprisingly,the competition index"basal area of larger trees"had showed a positive effect in four of the eight cohorts;iii)stand density had a negative effect on basal area increment,though the effect was minor in medium-and high-density stands,and iv)basal area growth was positively correlated with site quality except for an oak cohort.The developed species cohorts and growth models provide insight into their particular ecological features and growth patterns that may support the development of sustainable management strategies for temperate multispecies forests.

柴达木盆地新生代湖相叠层石沉积序列及古环境意义

气候、沉积环境和湖平面的演变直接或间接地影响湖相叠层石的生长,因而叠层石的出现可以作为此三者变化的判别标志。通过对比研究柴达木盆地西部地区西岔沟、长尾台两条新生代陆相地层剖面中近10个湖相叠层石的发育层位、垂向沉积序列,表明叠层石主要发育于新生代两个气候温暖湿润的高湖面时期,而且叠层石沉积亦同时出现在青藏高原其他邻近陆相新生代盆地,显示区域性的大规模异常湿润性气候,以强蒸发和强降水的交替为特征;划分出的4种含叠层石基本沉积序列中,叠层石可在泥岩或砂砾岩硬底上生长,含叠层石灰岩层之上通常是细粒碎屑沉积或间断面,这暗示了叠层石的生长出现在滨湖、浅湖相次级湖泛面附近,或指示湖水的突然加深。

HCV-RNA positivity in peripheral blood mononuclear cells of patients with chronic HCV-infection: does it really mean viral replication?

AIM To analyze the association of HCV-RNA with peripheral blood mononuclear cells (PBMC)and to answer the question whether HCV-RNA positivity in PBMC is due to viral replication,METHODS HCV-RNA was monitored in serumand PBMC preparations from 15 patients with chronic HCV infection before, during and after an IFN-α therapy using a nested RT/ PCRtechnique. In a second approach, PBMC from healthy donors were incubated in HCV positive plasma.RESULTS In the IFN-α responding patients,HCV-RNA disappeared first from total RNApreparations of PBMC and then from serum. In contrast, in relapsing patients, HCV-RNAreappeared first in serum and then in PBMC. A quantitative analysis of the HCV-RNAconcentration in serum was performed before and after transition from detectable to nondetectable HCV-RNA in PBMC-RNA and vice versa. When HCV-RNA was detectable in PBMCpreparations, the HCV concentration in serum was significantly higher than the serum HCV-RNA concentration when HCV-RNA in PBMC was not detectable. Furthermore, at no time during the observation period was HCV specific RNA observed in PBMC, if HCV-RNA in serum was under the detection limit. Incubation of PBMCfrom healthy donors with several dilutions of HCV positive plasma for two hours showed a concentration-dependent PCR-positivity for HCV-RNA in reisolated PBMC.CONCLUSION The detectability of HCV-RNA in total RNA from PBMC seems to depend on the HCV concentration in serum. Contamination or passive adsorption by circulating virus could be the reason for detection of HCV-RNA in PBMCpreparations of chronically infected patients.

Combination of "low-dose" ribavirin and interferon alfa-2a therapy followed by interferon alfa-2a monotherapy in chronic HCV-infected nonresponders and relapsers after interferon alfa-2a monotherapy

AIM To report on the efficacy, safety and tolerability of interferon alfa-2a combined with a "low dose" of ribavirin for relapsers and non responders to alpha interferon monotherapy.METHODS Thirty-four chronic hepatitis C virus-infected non-responders to interferon alfa2a monotherapy (a course of at least 3 months treatment) and 13 relapsers to interferon alfa 2a monotherapy (a dose of 3 to 6 million units three times per week for at least 20 weeks but not more than 18 months) were treated with the same dose of interferon alfa-2a used before (3 to 6 million units three times per week) and ribavirin (10 mg/ kg daily) for 6 months. In complete responders, interferon alfa-2a was administered for further 6 months at the same dose used before as monotherapy.RESULTS Seven (20.6%) of 34 non-responders stopped the combined therapy due to adverse events, including two patients with histological and clinical Child A cirrhosis. In 17/27 (63%)non-responders, the combined therapy was stopped after three months because of non-response. Ten of the 27 non-responders completed the 1;2-month treatment course. At a mean follow up of 28 months (16- 37 months)after the treatment, 4/10 (15%) previous non-responders still remained complete responders,All 13 previous relapsers completed the 12-month treatment course. At a mean follow up of 22months (9 - 36 months) after treatment, 6/13(46%) the previous relapsers were stillsustained complete responders.CONCLUSION Our treatment schedule of the combined therapy for 6 months of interferon alfa2a with a low dose of ribavirin (10 mg/kg/day)followed by 6 months of interferon alfa-2amonotherapy is able to induce a sustainedcomplete response rate in 15% of non-responders and 46% of relapsers with chronic hepatitis C virus-related liver diseases comparable to those obtained with the standarddoses of ribavirin 1000 - 1200 mg/day.Randomized prospective controlled trials using lower total amounts of ribavirin in combination with interferon should be performed.

Contemporaneous assembly of Western Gondwana and final Rodinia break-up:Implications for the supercontinent cycle

Geological,geochronological and isotopic data are integrated in order to present a revised model for the Neoproterozoic evolution of Western Gondwana.Although the classical geodynamic scenario assumed for the period 800-700 Ma is related to Rodinia break-up and the consequent opening of major oceanic basins,a significantly different tectonic evolution can be inferred for most Western Gondwana cratons.These cratons occupied a marginal position in the southern hemisphere with respect to Rodinia and recorded subduction with back-arc extension,island arc development and limited formation of oceanic crust in internal oceans.This period was thus characterized by increased crustal growth in Western Gondwana,resulting from addition of juvenile continental crust along convergent margins.In contrast,crustal reworking and metacratonization were dominant during the subsequent assembly of Gondwana.The Rio de la Plata,Congo-Sao Francisco,West African and Amazonian cratons collided at ca.630-600 Ma along the West Gondwana Orogen.These events overlap in time with the onset of the opening of the Iapetus Ocean at ca.610-600 Ma,which gave rise to the separation of Baltica,Laurentia and Amazonia and resulted from the final Rodinia break-up.The East African/Antarctic Orogen recorded the subsequent amalgamation of Western and Eastern Gondwana after ca.580 Ma,contemporaneously with the beginning of subduction in the Terra Australis Orogen along the southern Gondwana margin.However,the Kalahari Craton was lately incorporated during the Late Ediacaran-Early Cambrian.The proposed Gondwana evolution rules out the existence of Pannotia,as the final Gondwana amalgamation postdates latest connections between Laurentia and Amazonia.Additionally,a combination of introversion and extroversion is proposed for the assembly of Gondwana.The contemporaneous record of final Rodinia break-up and Gondwana assembly has major implications for the supercontinent cycle,as supercontinent amalgamation and break-up do not necessarily represent alternating episodic processes but overlap in time.

Evaluating alternative hypotheses behind biodiversity and multifunctionality relationships in the forests of Northeastern China

Background:The importance of biodiversity in maintaining multiple ecosystem functions has been widely accepted.However,the specific mechanisms affecting biodiversity and ecosystem multifunctionality(BEMF)relationships in forests are largely unknown.This is particularly evident for the macroscale of a large forested landscape.Methods:Based on 412 one-tenth hectare field plots distributed over forested areas across northeastern China,we evaluated three alternative hypotheses explaining the relationships between BEMF,namely:niche complementarity,mass ratio,and vegetation quantity effect.We used Rao's quadratic entropy and community weighted mean trait values to quantify forest“biodiversity”.These two variables represent two complementary aspects of functional properties,which are in line with niche complementary and mass ratio effects,respectively.Results:Ecosystem multifunctionality was negatively associated with the community weighted mean values of acquisitive traits(a proxy of mass ratio effect).Rao's quadratic entropy(a proxy of niche complementarity)had no relationship with ecosystem multifunctionality.Higher stand biomass greatly increased ecosystem multifunctionality,which is in line with the vegetation quantity effect.Our results confirm that in the temperate forests of northeastern China,the relationship of BEMF was primarily affected by vegetation quantity,followed by mass ratio effects.Conclusions:The results of this study contribute to a better understanding of the main drivers of ecosystem multifunctionality in forest ecosystems.The results of this study provide additional evidence to support the vegetation quantity and mass ratio hypotheses in forest ecosystems.

泌尿外科的HIV感染和艾滋病

虽然HIV感染与艾滋病发病后,主要由内科进行诊断与治疗,但几乎没有一个学科不被涉及到。特别是早期诊断与泌尿外科有关,所以对病程中许多重要症状的认识,在泌尿外科日常工作中往往是很重要的。

Effect of NaCl on growth and ion relations in two salt-tolerant strains of Paxillus involutus

The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl： 0, 100, 200 and 500 mmol·L^-1. Growth of MAJ and NAU was enhanced by 100 mmol·L^-1 NaCl but severely inhibited at the concentration of 500 mmol·L^-1. NAU exhibited a greater capacity to exclude Na^＋ and Cl^- under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na^＋/K^＋, Na^＋/Ca^2＋ and Na^＋/Mg^2＋ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L^-1 NaCl but markedly increased at 500 mmol·L^-1. This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na^＋ influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L^-1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.

克罗恩病患者成熟的树突状细胞增加:趋化因子介导的细胞浸润机制的新证据

Background and aims: Activation of T cells by dendritic cells (DC) is thought to play a pivotal role in induction and maintenance of Crohn’s disease. Detailed analyses however concerning the phenotype and maturation of DC as well as the mechanisms underlying their recruitment are still lacking for Crohn’s disease. Methods: Different myeloid and plasmacytoid DC subsets were characterised by immunohistochemistry. Expression of the so-called “lymphoid" chemokines CCL19, CCL20, and CCL21 was determined by real time reverse transcription-polymerase chain reaction in Crohn’s disease and normal controls. Furthermore, expression of CCL19, CCL20, and CCL21 as well as their receptors CCR6 (for CCL20) and CCR7 (for CCL19 and CCL21) was characterised by immunohistochemistry and, in addition, their cellular localisation was determined by double immunofluorescence investigations. Results: Colonic tissue affected by Crohn’s disease was characterised by an increased number of mature myeloid DC forming clusters with proliferating T cells. In keeping with their advanced maturation, DC possess the chemokine receptor CCR7. Increased expression of the CCR7 ligands CCL19 by DC themselves as well as CCL21 by reticular cells and lymphatic vessels was observed in Crohn’s disease, thereby causing the matured DC to be trapped at the site of inflammation. Conclusion: Our results demonstrate that autocrine and paracrine actions of lymphoid chemokines in Crohn’s disease may lead to increased numbers of mature DC away from their usual migration to lymphoid organs and result in the development of a tertiary lymphatic tissue within the bowel wall maintaining the autoimmune inflammation in Crohn’s disease.

Responses of Native Tree Species to Soil Water Stress in a Tropical Forest on Limestone,Vietnam

Forests over limestone in the tropics have received little attention and limestone forests in Vietnam have been overlooked to an even greater extent in terms of tree physiology. In Ba Be National Park, Vietnam, soil water availability in limestone forests seems to be the most limiting factor in the dry season. Therefore, in order to enhance the preliminary knowledge of choosing native tree species for enrichment planting in the restoration zone, characteristics of the 20 native tree species to soil water stress were investigated in a limestone forest. One-ha plot each consisting of twenty-five 20 m × 20 m plots was established in undisturbed forests. All trees ≥ 10 cm DBH were measured in 20 m × 20 m plots, while twenty-five 5 m × 5 m subplots were established in order to sample the regeneration of tree species with a DBH < 10 cm. The Scholander apparatus and freezing point osmometry were used in order to measure the leaf water potential (Ψw) and leaf osmotic potential (Ψπ) of the 20 native tree species, respectively in this study. 61 species belonging to 34 families of all trees with a DBH ≥ 10 cm were recorded in one ha, while 31 species representing 18 families of trees < 10 cm DBH were identified in 625 m2. The 20 species’ leaf water and osmotic potential values revealed significant differences among species. The maximum leaf water potential was not affected by any anticipated sources of variation, while the minimum water potential, however, showed significant variation to soil water stress. The results in the study area emphasized the importance of water factors in influencing tree species distribution;it could be concluded that native species with wide water potential ranges would be better able to withstand water changes and might be thus good candidates for reforestation (enrichment planting) in limestone areas.

未分化性小细胞型肝母细胞瘤

肝母细胞瘤(HB)为儿童期最常见的肝脏肿瘤，约占25%，几乎占恶性肝肿瘤的50%，其发病率随年龄递减，从5岁起实际上已无HB发生。 组织学上可将其分为上皮型(约56%)及混合型(44%)两型，前者包括未分化性小细胞型(2%～10%)、胚胎型(19%)、胎儿型(31%)或梁状型(3%)等亚型；后者则含有上皮性及间叶性两种成分。 未分化性小细胞型HB在鉴别诊断上应与儿童期的小细胞性、圆细胞性、蓝细胞性肿瘤，如神经母细胞瘤、Wilms瘤、横纹肌肉瘤、腹膜后小细胞性纤维增生性肿瘤，以及外周原始性神经外胚叶瘤相鉴别。 兹以一例15个月幼儿未分化性小细胞型HB为例，对其组织形态学、鉴别诊断进行探讨。

调节成骨细胞生成——与骨质疏松相关的病理生理

研究成骨细胞的分化过程和调节，对理解骨质疏松具有重要意义。成骨细胞来自骨髓多功能干细胞，后者也产生成纤维细胞、肌母细胞、软骨细胞和脂肪细胞。每种细胞的分化由其前体细胞决定，不能逆转。近年来许多研究表明，体外培养的成骨细胞前体及成骨细胞可进一步转化为脂肪细胞，这种转化对研究骨质疏松的发病机理具有重要意义。 成骨细胞与脂肪细胞的关系很容易使人联想到早已为人熟知的事实：随着年龄的增长，骨组织不断丢失，骨髓腔扩大，脂肪组织增加。骨质降低及骨骼硬度下降的原因是成骨细胞前体的分化受到干扰。例如，骨髓前体细胞分化为成骨细胞和脂肪细胞的比例受干扰而发生偏差，分化为成骨细胞的数量减少，而分化为脂肪细胞的数量增多。形态学观察发现局部成骨细胞减少导致骨髓代偿功能提高，黄骨髓大量增加。随年龄增加，骨髓脂肪细胞的大小和数量呈线性上升，而成骨细胞成骨能力却下降。实验条件下，加速老化的小鼠骨髓中，成骨细胞生成减少伴随脂肪细胞增加。培养的骨髓间质细胞不但具有成骨能力而且可分化为脂肪细胞。最近研究表明，原代培养的人骨髓细胞产生的成骨细胞具有成骨能力，同时又表达了脂肪细胞表型。目前还不清楚体外培养中分化出来的脂肪细胞是来自骨髓成骨细胞前体，还是在一定因子的作用下，已经分化完成的成骨细胞再次转化为脂肪细胞。Richard等通过PCR法发现骨髓间质细胞培养完全铺平、细胞遇合以前，脂蛋白脂酶表达；细胞相互遇合后，停止表达。但如果这时在培养液中加入地塞米松刺激，则脂蛋白脂酶的表达再次增加，细胞浆中脂肪滴增多。地塞米松和1，25-(OH)2-D3联合作用下，人骨髓间质细胞培养中脂肪细胞分化增加。骨髓组织块培养得到原代成骨细胞，在地塞米松和3-异丁基-1-甲基黄嘌呤(IBMX)作用下，脂肪细胞分化增加，IBMX是脂酶抑制剂，脂酶影响腺苷一磷酸的周期变化。脂肪细胞的分化受白介素1(IL-1)、肿瘤坏死因子(TNF)和生长转化因子(TGF-β)的抑制。

Transgenic Poplar Plants for the Investigation of ABA-Dependent Salt and Drought Stress Adaptation in Trees

Important functions of the plant hormone abscisic acid (ABA) in stress reactions, growth and photosynthetic processes are extensively studied in the model plant Arabidopsis thaliana. This paper investigates the importance of Moco-sulphurase ABA3 and aldehyde oxidase (AO) on ABA-biosynthesis in Populus × canescens. ABA3 is essential for activation of the molybdenum enzymes AO and xanthine dehydrogenase (XDH). AO itself catalyzes the last step in ABA-biosynthesis. Generation of transgenic poplar plants altered in ABA3 and AO-activity using RNAi knock down and overexpression was performed. Whereas RNAi-AO plants show a specific loss of AO activity, the RNAi-ABA3 plants has a strongly reduced activity of both molybdenum enzymes: AO and XDH. Constructs of AO and ABA3-promoters fused to β-glucuronidase provide the basis to investigate transcriptional regulation of ABA-biosynthetic processes under stress conditions. Application of high salt concentrations and different drought stress intensities does change the endogenous AO or XDH neither on the side of transcription nor on protein activity. On phytohormone level however, water loss leads to increased ABA-amounts regardless of whether transgenic or wildtype plants are studied. Salt application resulted in higher ABA-levels in all analyzed plant lines. The down regulation of AO in the two different RNAi-plant lines strongly prevented a wildtype-like increase of ABA-levels. Whereas the WT plants accumulated up to 6000 ng ABA g-1 FW-1 after 16 h of salt stress exposure, plants of the RNAi lines revealed a markedly lower increase of only up to 2000 ng ABA g-1 FW-1. Opposing to these observations, ABA-levels increased during drought without any influence by the RNAi-effect. These results revealed that although stresses did not result in a visible increased AO-activity, ABA-production was influenced by AO and ABA3 at least under salinity.

A multi-layered policy generation and management engine for semantic policy mapping in clouds

The long awaited cloud computing concept is a reality now due to the transformation of computer generations.However,security challenges have become the biggest obstacles for the advancement of this emerging technology.A well-established policy framework is defined in this paper to generate security policies which are compliant to requirements and capabilities.Moreover,a federated policy management schema is introduced based on the policy definition framework and a multi-level policy application to create and manage virtual clusters with identical or common security levels.The proposed model consists in the design of a well-established ontology according to security mechanisms,a procedure which classifies nodes with common policies into virtual clusters,a policy engine to enhance the process of mapping requests to a specific node as well as an associated cluster and matchmaker engine to eliminate inessential mapping processes.The suggested model has been evaluated according to performance and security parameters to prove the efficiency and reliability of this multilayered engine in cloud computing environments during policy definition,application and mapping procedures.

骨CT扫描结果的三维重建(评价)

现今已能对图像进行三维重建,直观显示正常的和病理的骨结构.倘若期待从平面重建得出辅助诊断是不会有什么收获的.但是未来的发展不可估量,所以这期待也是有道理的.

Enhanced Structural Complexity Index:An Improved Index for Describing Forest Structural Complexity

The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.

过渡金属催化的区域选择性芳烃C—H键氧化生成C—O键（英文）

近年来过渡金属催化的芳烃直接C—H氧化反应取得了重要进展,该策略被用于多种酚类化合物的制备.反应体系使用的过渡金属催化剂包括钯、铜、钌、铱等;氧化剂包括高价碘化合物、过硫酸盐、氧气等.此前已有多篇综述就特定的过渡金属或氧化剂参与的C—H氧化反应进行了详尽的讨论.本综述着重探讨过渡金属催化的邻、间、对位选择性的芳烃C—H氧化反应,并试图阐释上述区域选择性的产生机制,其中包括导向基团的螯合辅助作用、配体控制、底物自身因素等.在讨论部分提出了过渡金属催化的芳烃C—H氧化反应中存在的问题以及影响该策略发展应用的可能限制因素.

Transcriptional Activation and Production of Tryptophan-Derived Secondary Metabolites in Arabidopsis Roots Contributes to the Defense against the Fungal Vascular Pathogen Verticillium Iongisporum

The soil-borne fungal pathogen Verticillium Iongisporum causes vascular disease on Brassicaceae host plants such as oilseed rape. The fungus colonizes the root xylem and moves upwards to the foliage where disease symptoms become visible. Using Arabidopsis as a model for early gene induction, we performed root transcriptome analyses in re- sponse to hyphal growth immediately after spore germination and during penetration of the root cortex, respectively. Infected roots showed a rapid reprogramming of gene expression such as activation of transcription factors, stress-, and defense-related genes. Here, we focused on the highly coordinated gene induction resulting in the production of tryp- tophan-derived secondary metabolites. Previous studies in leaves showed that enzymes encoded by CYP81F2 and PEN2 （PENETRATION2） execute the formation of antifungal indole glucosinolate （IGS） metabolites. In Verticillium-infected roots, we found transcriptional activation of CYP81F2 and the PEN2 homolog PEL 1 （PEN2-LIKE1）, but no increase in antifungal IGS breakdown products. In contrast, indole-3-carboxylic acid （13CA） and the phytoalexin camalexin accumulated in infected roots but only camalexin inhibited Verticillium growth in vitro. Whereas genetic disruption of the individual metabolic pathways leading to either camalexin or CYP81F2-dependent IGS metabolites did not alter Verticillium-induced disease symptoms, a cyp79b2 cyp79b3 mutant impaired in both branches resulted in significantly enhanced susceptibility. Hence, our data provide an insight into root-specific early defenses and suggest tryptophan-derived metabolites as active anti- fungal compounds against a vascular pathogen.

Cobaltaelectro-Catalyzed C—H Acyloxylation

Cobaltaelectrocatalysis set the stage for sustainable C—H acyloxylations in biomass-derived γ-valerolactone as a renewable solvent. The sustainable electrocatalysis regime featured ample scope, along with high levels of chemo- and position-selectivity.