基于明度的曼德拉山岩画断代及数量分析

根据岩画画面的不同内容,将曼德拉山地区岩画分为6种类型,突显其沙漠特点.运用明度模式测得曼德拉山64幅岩画的明度值,根据已知2004年和西夏岩画的年代和明度值,得到其他未知岩画的大致年代.结果发现,从三国、两晋、南北朝时期(220-280 AD、281-419 AD、420-580 AD),历经隋(581-617 AD)、唐(618-906 AD)、西夏(1038-1227 AD)、元(1279-1367 AD)直到明清之际(1368-1643 AD、1644-1911 AD)一直有古人在此地作画.岩画年代频数大值集中在700 AD前后,即盛唐时期,在1500 AD前后频数最低,即明清之际,与中国历史上的暖期和冷期相对应,说明气候变化,尤其是温度波动为岩画数量的主要影响因素.在气候温暖期,自然灾害较少,农业产量高,温饱问题有所保障,就会有闲暇时间去创作岩画;气候寒冷期,则与之相反,人们为了生存无暇顾及艺术创作.曼德拉山地区岩画年代与数量同历史时期气候有一定关联.     

AD9240及其在中频数字化接收机中的应用

AD9240是AD公司推出的高速14位并行A/D转换芯片,在数字信号处理领域中得到广泛应用.介绍了AD9240的基本特点、结构和工作原理,并结合所设计的中频数字化接收机说明了AD9240的应用.     

阿尔茨海默病致病基因突变相关的啮齿类动物和非人灵长类动物模型

摘要: 我国现有阿尔茨海默病( AD) 患者800 － 1000 万,患者数量随着人口老龄化逐年增加,目前尚无有效治疗或者逆转AD 的药物和方法。过去基于啮齿类动物模型筛选出的用于治疗AD 的药物在人体试验中均疗效差或有严重的副作用,这与啮齿类动物模型和AD 患者病理及行为特征差异大有直接关系。非人灵长类动物与人的大脑和神经系统高度相似,建立AD 非人灵长类动物模型意义重大。AD 病因复杂,但是致病基因突变是其已知的明确病因,应该重视利用基因修饰或者基因筛选等技术建立AD 非人灵长类动物模型。本文将着重介绍AD 致病基因突变相关的转基因小鼠模型和非人灵长类动物模型的特点和现状。     

阿尔兹海默病的发病机制及药物治疗研究进展

阿尔兹海默病(Alzheimer’s disease,AD)是老年痴呆中最常见的类型,属于慢性的神经退行性疾病。AD是与年龄密切相关的疾病,伴随社会人口老龄化的到来,AD的发病率明显增加,防治AD已成为全球性的重大研究课题。近年来,针对AD的发病机制以及相关药物治疗取得了新进展,通过归纳AD的发病机制以及药物治疗的研究进展,以期为AD相关研究提供参考。     

Temporal and spatial variations in the Palmer Drought Severity Index over the past four centuries in arid, semiarid, and semihumid East Asia

Based on a database of 106 annually resolved tree-ring chronologies and 244 Palmer Drought Severity Index(PDSI)grid data,we attempted to reconstruct gridded spatial drought patterns in each year over the past four centuries in the arid,semiarid,and semihumid East Asia.The results showed that these regions mainly experienced drought events during the periods from AD 1601 to AD 1652,AD 1680 to AD 1718,AD 1779 to AD 1791,AD 1807 to AD 1824,AD 1846 to AD 1885,and AD 1961 to AD 1999.In the middle of the 16th century,severe droughts occurred mainly in North China;during the period from AD 1876 to AD 1878,droughts occurred in most parts of northern China;and from the 1920s to 1940s,catastrophic drought events spread across almost all of northern China and Mongolia.These historical drought events caused severe ecological and environmental problems and substantially affected the development of human society.In these regions,temperature and summer monsoon precipitation are the main factors influencing drought events.In western areas,PDSI and temperature exhibit a close relationship,whereas in eastern areas,summer monsoon rainfall is the dominant factor influencing variations in PDSI.     

T检验识别阿尔茨海默病候选致病基因及基因生物分析

医学研究表明阿尔茨海默病(AD)的致病机制与基因有关,过高或过低的基因表达水平异常都会让人体失去平衡,产生病变.利用T检验法对基因芯片公共数据库GEO中的4种AD样本的基因芯片数据进行分析,提取出具有重要意义的显著差异表达基因,再通过这些差异基因的生物信息学分析其在AD发病机制中的作用,为AD致病机制的探询、预防、早期诊断与治疗等提供有益的途径和方法.通过该算法的筛选、结合AD发病机制的假说及基因生物学分析,最终识别出30个AD候选致病基因,其中有5个已经被确定为与AD有关,10个被AD致病基因筛选算法识别.     

阿尔兹海默症口腔病原体感染假说的研究进展

阿尔兹海默症(Alzheimer′s disease,AD)是一种慢性神经退行性疾病.迄今为止,已经有较多关于AD发病机制的报道,但是尚未发现确切有效的治疗药物.近年来,研究者相继在AD患者脑中检测到口腔病原体,并据此提出了口腔病原体感染引发AD的假说.从机制上来说,口腔病原体侵入脑后,病原体脂多糖(li-popoly...     

基于AD公司器件的TETRA基站中频数字化实现方案

本文介绍了一种基于AD公司专用器件的TETRA基站中频数字化方案,文中分析了中频数字化的特点,针对TETRA基站系统的需求给出了主要部件之间的电路原理图,详细介绍了AD6623,AD6624,AD9772,AD6640等器件的特性和工作原理。本方案完全能满足TETRA基站系统的需求。     

基于智能影像基因组学技术的阿尔茨海默病预测进展

 阿尔茨海默病（AD）起病隐匿,目前尚无有效控制病情进展以及治疗的药物或方法。在其发病轻度认知功能障碍阶段早期预测进行干预,则能有效控制其病程。从基于脑影像组学特征的AD早期临床诊断、基于人工智能影像组学技术的AD早期预测两个方面综述了AD的早期诊断与预测研究进展,提出结合多模脑核磁共振影像特征和组学特征,在深度学习的框架下,将影像学和基因组学联系在一起,构造高分类与预测性能的深度学习模型,可为AD早期筛查并干预提供支持。     

内分泌干扰物对雄激素受体功能的干扰

内分泌干扰物(Endocrine disrupting chemicals,EDC)是指干扰内源激素的生物合成、代谢和功能,从而干扰动物内分泌系统的外源活性物质。本文特别介绍了做为EDC类物质之一的雄激素干扰物(Androgen disruptors,AD)的不同种类和生理效应。AD可与雄激素受体(Androgen receptor,AR)结合发挥AR激动剂或拮抗剂作用,其中做为激动剂的AD主要有1,2-二溴-4-环己烷(TBECH);做为拮抗剂的AD主要有氟他胺类、有机氯杀虫剂类、二苯甲烷类、双酚A、邻苯二甲酸酯、烷基酚类等。它们通过多种分子机制干扰AR的功能,进而对动物的生殖和发育等功能产生严重影响。本文认为在国内应加强对AD的深入研究,并重视AD对鱼类等非哺乳类动物的影响的研究;同时应注重从源头上阻止AD在环境中的扩散和二次污染,并大力发展生物植被降解技术、光催化技术、新型纳米材料吸附、人工生态系等生态修复技术,建立无毒、无内分泌干扰效应的AD高通量筛选技术,以消除AD对生态系统的不良影响。     

基于软件无线电的通用数字调制器的实现

软件无线电的基本思想是构造一个通用的硬件平台,将通信的各种功能尽可能用软件实现．数字上变频是软件无线电的关键技术之一,主要功能是对输入数据进行各种调制和频率变换．AD9857是通用数字正交上变频器,具有可编程性、体积小,速度快,性能高等特点．详细介绍了该器件的原理、结构与使用方法,分析了软件无线电调制算法的特点,给出了一个利用FPGA与AD9857相结合而实现通用的数字调制系统平台的实例．     

基于零中频的短波发射机DSP单元设计与实现

由于短波的频段比较窄,利用高性能的上变频器AD9857来实现零中频的、直接射频的短波发射机.基于零中频的短波发射机DSP单元是发射机的核心单元,主要包括基带滤波、调制及射频产生、AGC(Auto Gain Control,自动增益控制)、ALC(Auto Level Control,自动功率控制)等功能模块.重点分析DSP单元的电路实现及以上功能模块的设计方法与实现.     

东海内陆架泥质沉积Rb和Sr的地球化学及其古气候意义

通过对位于东海内陆架闽浙沿岸泥质沉积区北部的DD2孔进行AMS14C年龄测试和Rb,Sr含量测定,获得了近2ka的Rb/Sr比值(RRb/Sr)变化的高分辨率曲线。该曲线揭示出10次RRb/Sr低值时期,它们与历史时期中国温度下降有很好的对应关系,并印证了约990AD的降温事件。根据RRb/Sr的变化,基本认同竺可桢所界定的隋唐温暖期,并认为气候存在温暖-寒冷-温暖的波动,且其中的相对寒冷期为800-890AD。研究认为小冰期时间段为1480-1890AD,且由3个寒冷阶段构成,小冰期的最冷峰为约1520AD,1670AD,1780AD和1850AD。     

沼气厌氧消化过程影响因素研究进展

沼气厌氧消化过程涉及复杂微生物群落在厌氧环境下的协同作用,此过程中的因素变化会导致菌群结构发生改变,进而影响发酵系统的稳定性和效率。本文对影响厌氧发酵过程稳定和效率的因素进行了探讨,包括发酵温度、pH值、碳氮比、有机负荷、停留时间及营养元素等。认为厌氧发酵过程采用混合原料可以弥补单一原料发酵过程的养分不足和特定成分积累对发酵过程稳定性的影响;在发酵温度的选择上,要充分考虑能源输入/输出比,才能保证过程的经济性。     

What can false memory tell us about memory impairments in Alzheimer’s disease?

The range of memory impairments associated with Alzheimer’s disease (AD) has been a focus for psychological and clinical re-searchers for many years. In addition to investigations of AD patients’ veridical memory using traditional recognition memory tasks, a number of recent studies have focused on false memories to reveal the underlying causes of memory impairment in AD. Studies comparing illusory memories between AD patients and healthy older people have revealed various differences in memory deficits between the development of AD and the typical aging processes. Here, we review 3 types of memory illusions tested in AD patients: associative memory illusions, fluency-based false memories and source memory errors. By comparing AD patients with healthy older adults, we sought to analyze the mechanisms underlying AD-related memory impairments at different stages of memory processing, including encoding, retrieval and monitoring. This comparison revealed that AD patients exhibit an impaired ability to establish and utilize gist representations at the encoding stage and impairments in processing on the basis of familiarity and recollection at the retrieval stage. Consequently, patients with AD have access to less information when making memory judgments. As a result, they become more susceptible to the effects of item fluency, which can be manipulated during the retrieval stage. Furthermore, with impaired source memory monitoring abilities, the capacity of AD patients to suppress memory illusions is compromised. Based on these findings, we propose that the study of false memories constitute a critical tool for elucidating the memory impairments involved in AD. Further explorations of these memory impairments will have practical significance for the diagnosis and treatment of AD in the future.     

Segregation of a missense mutation in the amyloid precursor protein gene with familial Alzheimer's disease.

A locus segregating with familial Alzheimer's disease (AD) has been mapped to chromosome 21, close to the amyloid precursor protein (APP) gene. Recombinants between the APP gene and the AD locus have been reported which seemed to exclude it as the site of the mutation causing familial AD. But recent genetic analysis of a large number of AD families has demonstrated that the disease is heterogeneous. Families with late-onset AD do not show linkage to chromosome 21 markers. Some families with early-onset AD show linkage to chromosome 21 markers, but some do not. This has led to the suggestion that there is non-allelic genetic heterogeneity even within early onset familial AD. To avoid the problems that heterogeneity poses for genetic analysis, we have examined the cosegregation of AD and markers along the long arm of chromosome 21 in a single family with AD confirmed by autopsy. Here we demonstrate that in this kindred, which shows linkage to chromosome 21 markers, there is a point mutation in the APP gene. This mutation causes an amino-acid substitution (Val----Ile) close to the carboxy terminus of the beta-amyloid peptide. Screening other cases of familial AD revealed a second unrelated family in which this variant occurs. This suggests that some cases of AD could be caused by mutations in the APP gene.     

Development in the research of molecular mechanism of Alzheimer’s disease

Alzheimer's disease (AD) is a kind of central nervous system disease. The cause of AD is unclear. It is found that the remarkable histopathological characters of AD are senile plaques and neurofibrillary tangles. β-amyloid plays an important role in the formation of senile plaques and the abnormal phosphorylation of Tau protein is the main reason of neurofibrillary tangles. Apolipoprotein E is correlated to AD' s access, and the third pathological character-AMY plaque perhaps represents a new cause of AD. Presenlin and proteinaceous infectious particles are also related with AD. A summary of molecular mechanism for AD and the development of research is presented.     

证病结合的异常黑胆质型阿尔茨海默病(AD)模型的建立及行为学改变

 在前期已建立的异常黑胆质载体动物模型的基础上,采用聚集态Aβ1-40 双海马定向注射制备证病结合的异常黑胆质型阿尔茨海默病(AD)模型,并以Morris 水迷宫及跳台实验验证证病结合模型的行为学改变特点。结果表明,各组大鼠饮食、水量及体重变化:单纯(AD)组、异常黑胆质证组饮食、水量较正常对照组增加(P<0.05);证病结合的异常黑胆质型AD 模型组饮食、水量较异常黑胆质组减少(P<0.01);单纯AD 组、异常黑胆质证组、证病结合组体重较正常对照组均减轻(P<0.01)。各组大鼠Morris 水迷宫空间探索试验经过有效区域次数:与正常对照组比较,单纯AD 组、异常黑胆质证组、证病结合组经过有效区域次数均减少(P<0.01);与单纯AD 组相比,证病结合组经过有效区域次数明显减少(P<0.05)。各组大鼠跳台测试:与空白对照组比较,单纯AD 组、异常黑胆质证组和证病结合组反应期延长,潜伏期缩短,错误次数增多,学习记忆成绩明显降低(P<0.01);证病结合组与单纯痴呆组相比略低,但无统计学差异(P>0.05)。由此得出,在异常黑胆质载体大鼠模型的基础上,采用聚集态Aβ1-40 双海马定向注射制备证病结合的异常黑胆质型AD 模型,不仅动物体表特征的变化符合维医体液证候改变特点,通过行为学验证后学习记忆改变特点又符合西医疾病的特点。