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Prospective protochordate homologs of vertebrate midbrain and MHB, with some thoughts on MHB origins
Thurston C. Lacalli
International Journal of Biological Sciences , 2006,
Abstract: The MHB (midbrain-hindbrain boundary) is a key organizing center in the vertebrate brain characterized by highly conserved patterns of gene expression. The evidence for an MHB homolog in protochordates is equivocal, the "neck" region immediately caudal to the sensory vesicle in ascidian larvae being the best accepted candidate. It is argued here that similarities in expression patterns between the MHB and the ascidian neck region are more likely due to the latter being the principal source of neurons in the adult brain, and hence where all the genes involved in patterning the latter will necessarily be expressed. The contrast with amphioxus is exemplified by pax2/5/8, expressed in the neck region in ascidian larvae, but more caudally, along much of the nerve cord in amphioxus. The zone of expression in each case corresponds with that part of the nerve cord ultimately responsible for innervating the adult body, which suggests the spatially restricted MHB-like expression pattern in ascidians is secondarily reduced from a condition more like that in amphioxus. Patterns resembling those of the vertebrate MHB are nevertheless found elsewhere among metazoans. This suggests that, irrespective of its modern function, the MHB marks the site of an organizing center of considerable antiquity. Any explanation for how such a center became incorporated into the chordate brain must take account of the dorsoventral inversion chordates have experienced relative to other metazoans. Especially relevant here is a concept developed by Claus Nielsen, in which the brain is derived from a neural center located behind the ancestral mouth. While this is somewhat counterintuitive, it accords well with emerging molecular data.
碎药先用  [PDF]
曾智永
中国中药杂志 , 1985,
Abstract: <正>根茎类中药饮片在切制、干燥和搬运过程中,或多或少都会产生一些碎片碎末,尤其是用机器切片时碎片碎末更多。这些碎片、末丢掉造成浪费,留着不但影响药物外观,而且因其易吸潮、发霉、生虫、变色,某些药的有效成份易挥发等,给中药饮片保管带来困难,同时也降低了饮片质量。针对这种情况,我们在工作中摸索了一个“碎药先用”的方法,即对含有碎片碎末的饮片进行过筛(筛子粗细根据药物片型的大小而定),过筛后,碎药与合格饮片分开貯藏,做到仓库先发、药房先用。通过几年来的实践观察,碎药先用不但可使根茎类饮片外观好看,而且有利于防止这些药物虫伤、霉变
SWS promoting MHb-IPN-MRN circuit opposes the theta promoting circuit, active wake and REM sleep  [PDF]
Karin Vadovi?ová
Quantitative Biology , 2015,
Abstract: The multisynaptic axonal tracts between hippocampus and medial habenula (MHb) observed in my DTI study using probabilistic tractography made me explore their connectivity. Found tract linked hippocampus to septum, and amygdala to bed nucleus of stria terminalis (BNST). Axons from septum and BNST passed by anteromedial thalamic nucleus (AM) to MHb, and from MHb to pineal gland, linked to control of circadian cycles and sleep. Combination of known findings about septum and MHb connectivity and function led to idea that posterior septum activates MHb, leading to activation of IPN, MRN and serotonin release. This MHb-IPN-MRN circuit promotes slow wave sleep (SWS), high serotonin and low acetylcholine state. This SWS promoting circuit reciprocally suppresses the theta oscillations promoting circuit, linked to high acetylcholine in brain, and formed by supramamillary area (SUM) projections to the medial septum (MS) that activates hippocampus or other theta-coupled regions. The MHb pathway inhibits, possibly reciprocally also some stimulating input to theta-generating SUM and MS, from wake-on nucleus incertus (NI), posterior hypothalamus (PH) and laterodorsal tegmentum (LDT) neurons, and REM-on reticular nucleus pontis oralis (PnO). So the SWS- promoting circuit attenuates theta and both active wake state and REM sleep promoting regions. As the theta in wake state is linked to recording and binding information with their spatio-temporal and relational context by hippocampus, while the SWS supports replay of hippocampally stored information/memory trace and its cortical reactivation, e. g. in retrosplenial cortex linked to autobiographic memory or in prefrontal cortex that can combine any information.
机械筑埽技术研究  [PDF]
张佑民,苏本超,梅龙
人民黄河 , 2008,
Abstract: ?分析了机械修筑传统埽体、柳石混杂机械筑埽和层柳层石机械筑埽的施工工艺,与人工作业筑埽相比,作业优势明显,可在黄河防汛抢险中大力推广.
水泥混凝土路面MHB法碎石化环境影响分析与评价  [PDF]
阎宗岭,高艳龙,冯学钢
公路交通科技 , 2008,
Abstract: 为了掌握既有水泥混凝土路面MHB法碎石化改造时对周围环境的振动特点与影响范围,采用高精度震动测试仪对水泥混凝土路面MHB法碎石化时的施工振动特点、影响范围等进行了现场施工监测。对试验段现场振动测试的振动加速度时程曲线、加速度衰减特性曲线和加速度峰值随振中距衰减曲线的变化进行了对比、分析。表明采用MHB法对旧混凝土路面碎石化施工时所产生的机械振动加速度衰减速度很快,且具有冲击和瞬态振动的特点,对以填方为主在路堤边坡和挖方路堑边坡的安全影响范围与岩土体性质密切相关。通过试验建立了填方路基和挖方边坡的水平加速度和垂直加速度与MHB法碎石化振中距间的负指数和对数关系式,确定了混凝土路面MHB法碎石化振动对填方路基下边坡和挖方路堑上边坡上建筑物影响范围和最小安全距离,分别为5.5m和25m。
竹弓提?碎?方法  [PDF]
于?
地质与勘探 , 1958,
Abstract: 在野外普查或小型矿区进行?料加工时,一般均用手提?的方法碎样,这样不仅劳动强度大,而且效率也很低。我??用竹弓代替人工提?,效率有显著的提高。其方法是?一长?2―4公尺,粗?5―10公
碎药的综合利用  [PDF]
胡金林
中国中药杂志 , 1988,
Abstract: <正>中药饮片在采购、加工炮制、清理药屉及贮藏过程中,往往会产生一些碎药(碎片、碎末)。若将这些碎药不筛选出来,直接应用于临床配方,不但影响药物外观,而且因其易吸潮、发霉等因素,给贮藏、保管带来较大困难,同时也会降低饮片质量。因此为了保证中药饮片的净度和美观,在配方前饮片必需进行适当处理,把其中的一些碎药筛选出来。筛选出来的碎药怎么办?如把碎药当作垃圾丢掉,弃而不用,就会造成浪费,这对药材资源与经济效益都是不利的。为此,笔者就碎药如何开发利用谈谈以下浅见。
冲击压实与MHB类设备对水泥混凝土路面破碎效果的对比  [PDF]
李昶,张玉宏,张建
公路交通科技 , 2004,
Abstract: 常规方式处理破坏严重的水泥混凝土路面时存在效率低、费用高的缺点,目前我国逐渐采用冲击压实设备进行破碎的工艺,山东省公路局近年又引进了MHB(MultipleHeadBreaker,多锤头破碎机)类水泥混凝土路面碎石化(Rubblization)设备。本文主要从破碎效果对2种设备进行对比,通过2种工艺破碎后表面回弹弯沉及回弹模量等测试数据,分析2种工艺处治后结构层表面的强度变异性。结果显示,MHB设备破碎的水泥混凝土路面具有更好的强度均匀性,可以作为新加铺路面的基层。
利用“?米坎”碎?方法介绍  [PDF]
敖振宽
地质与勘探 , 1958,
Abstract: 于?同志提出的“竹弓提?”碎样法(?地?与勘探1958第3期),对于仅有极??设备的预查或普查队在矿样加工工作上,的确比用手提?碎样省时省力,效率增高。但由于在操作时,必需手持“弓背”不停的作功,还是易于疲劳。我?在野外普查时曾利用农村里的“椿米坎”(南方农村皆有)碎样,取得了良好的效果。“椿米坎”之式样与?造如图1所示。一般“杵”与
响叶杨(populusadenopoda)种子的形成及其寿命  [PDF]
吴琼美,樊汝汶
南京林业大学学报(自然科学版) , 1984, DOI: 10.3969/j.jssn.1000-2006.1984.01.014
Abstract: <正>用显微技术及软x射线摄影,定位观察响叶杨种子发育过程中的形态变化与胚胎发育的对应关系。根据观察、试验的结果,讨论了环境条件与种子寿命的关系;还测定了响叶杨种子寿命的变化规律及其影响因素,探索延长这种子寿命的方法。
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