植入式电子系统中射频线圈的失配分析

植入式电子系统中常采用射频线圈进行电磁耦合来进行体内外信息和能量的传输。本文着重讨论体内外两个射颦圈在耦合存在空间几何失配时互感系数Ｍ的变化与计算方法,并给出典型几何失配情况下,系统输出电压、功率和效率变化的实验结果。     

用于研究快速扫视对瞳孔光反射调制作用的新方法

瞳孔对光反射系统和快速扫视系统在解剖学和功能上都有着紧密的联系,但是快速扫视系统对瞳孔的光反射系统是否有调制作用尚无报道。研究这两个系统间的调制作用,必须了解光刺激不均匀和近反应对瞳孔直径变化是否有影响。该研究以人为被试,设计了一种全新的实验方法,研究光刺激不均匀和近反应对瞳孔直径变化的影响。实验方法：将被试的一只眼用密闭的眼罩罩住给予脉冲光刺激,刺激由位于眼罩内全视野范围水平排列的一排发光二极管(light emitting diodes,LEDs)给出,被试的另一只眼用来记录眼动和瞳孔直径的变化,研究水平方向的快速扫视对瞳孔对光反射时瞳孔直径变化的影响。实验结果：比较被试注视视野内不同位置的瞳孔对光反射相对收缩率无显著差异（P=0.148, 非配对样本t检验）。结论：本方法消除了光刺激不均匀和近反应对瞳孔直径变化的影响,可用于研究快速扫视系统对瞳孔光反射系统间的调制作用。     

沙质林地土壤阻抗系数测量方法

介绍了土壤阻抗系数的测量目的及测量的一般方法;重点描述了应用大地阻抗仪(Yokogawa Type 3244)(specific earth resistance tester)测量沙质林地土壤阻抗系数的理论背景和室内、外操作步骤与数据处理方法。结果表明,使用3244大地阻抗仪,即运用Wenner法测量沙质林地土壤阻抗系数是可行的。其测量结果在对土壤分层、确定表层土壤含水量、初步确定地下水位等具有一定的应用前景。     

余弦形负载超声变幅杆的设计与研究

研究余弦形负载超声变幅杆特性。求解了加负载时四种超声变幅杆的输入阻抗,得到加负载时输入阻抗和Mbius变换参数的统一算式。当变幅杆的输入抗分量为零时,计算了余弦形负载变幅杆的纵向振动共振频率方程和放大系数。由输入阻抗的表达式讨论了此类变幅杆的工作稳定性条件和相对阻抗相等点。结果表明由两种方法计算的共振频率方程是相同的;余弦形变幅杆的各种参量和方程与负载阻抗紧密相关;有负载力阻时1/4波长变幅杆的放大系数要比1/2波长变幅杆显著的多,和杆两端特性阻抗的几何平均值成正比,而与负载力组成反比。     

基于结构方程模型的吴起县农业生态经济系统耦合关系

基于2008年吴起县农户调查资料,利用结构方程模型对吴起县农业生态经济系统耦合关系进行了分析.结果表明：具有相关关系的农业资源和产业态势对系统耦合有一定影响,其影响系数分别为0.14和1.00;农业资源与产业态势之间的相关系数为-0.11,说明吴起县的产业发展并非建立在对农业资源有效利用基础之上,农业资源对经济效益的变化没有直接作用;产业的发展主要建立在对农业资源之外的能量和物质的开发利用上,导致产业态势对经济效益的直接路径系数为-2.95,总的路径系数仅为0.23.从农业生态系统与经济系统的关系及其耦合的角度看,目前研究区农业系统建立在不稳定的、较少依赖于本系统资源的耦合态势下,即在农业生态经济系统良性耦合机制的建立与形成过程中潜伏了较大危机.为此,需要提高牧草等农业资源的利用率,发展林草及其相关产业.     

肠—肠抑制反射及其条件反射的建立

在狗的慢性实验中,以5—10毫米水银柱的压力扩张一段小肠时,本段肠发生整齐的节律性收缩活动,如压力在25毫米水银柱左右时,则发生阵发性节律收缩及相应的紧张度的变化,更大压力引起广泛的肠抑制反射。重覆刺激可提高感受野的敏感性。大脑皮层对小肠的节律性活动及小肠运动的抑制反射具有影响,睡眠时肠运动减弱,而新异动因对肠抑制反射有外抑制作用,动物在暴燥不安时,不易引起肠抑制反射。在肠—肠抑制反射的基础上,可以节拍器及电铃声建立条件反射,约40次结合后条件反射即可明显出现。在长期间隔后,条件反射消退,但很容易重新建立起来。     

土壤镉污染对水稻叶片光谱反射特性的影响

水稻移栽于添加不同量镉(50、100、200和400 ppm)的土壤上,叶片反射光谱特性发生变化:可见光区反射率增加,其中550—680nm波段反射率的增加更突出;反射光谱的一次微分图和二次微分图上叶绿素吸收边缘明显蓝移。这些变化以分蘖期最为显著。镉害水稻可见光区反射特性的变化与叶片中叶绿素含量的降低相一致。初步确定几个波段可用于区分镉毒害的和正常的水稻的光谱反射特性。     

利用Imaging-PAM研究莱茵衣藻对环境变化的响应

本文介绍了Imaging—PAM—M—Series调制叶绿素荧光成像技术在莱茵衣藻活体叶绿素荧光检测中的应用。该方法利用CCD对藻体直接成像,可同时检测多个样品。后期分析可获得图像中任意区域的初始荧光产量（R）、充分暗适应后PSII的最大光化学效率（眠）、PSⅡ光化学能量转化的有效量子产量【Y（Ⅱ）】、光化学淬灭系数（qp）、非光化学淬灭系数（NPQ）等指标。文章以敌草隆[3-（3,4-dichlorophenyl）-1,1-dimethylurea,DCMU]和没食子酸丙酯（propyl gallate,PG）对莱茵衣藻野生型及其抗DCMU突变体的影响为例,说明该技术在莱茵衣藻研究中是可靠的,具有简单、快速、灵敏等特点。     

珠江三角洲稻田区黄毛鼠种群动态预测模型的研究

本文研究稻田区黄毛鼠种群动态预测模型,利用数量化理论Ⅰ建立起预测模型。在预测方程中考虑七类与黄毛鼠生存有关的生态因子,即繁殖指数,降雨量、相对湿度、平均温度、农时变化,作物换茬和季节变化。本文还利用偏相关系数的T检验,分析影响黄毛鼠种群数量变化的主、次要生态因子。其中繁殖指数、作物换茬、农时变化和季节变化为主要影响因子。同时采用双因素方差分析讨论了1987—1989年降雨量的变化,认为年度间降雨量差异不明显,月份间降雨量差异明显。还分析了作物换茬,农时变化种群密度的影响。     

大鼠脊髓内甲啡肽、亮啡肽和甲七肽在镇痛和电针镇痛中的不同作用

1.给大鼠脊髓蛛网膜下腔注射甲啡肽200—800nmol引起与剂量相关的镇痛效应。注射脑啡肽降解酶抑制剂Thiorphan 50nmol或Benatin 300nmol可加强电针镇痛,注射甲啡肽抗体则可对抗电针镇痛。这些资料说明内源性甲啡肽确实在痛觉调制系统中起着重要作用。 2.脊髓蛛网膜下腔注射亮啡肽800nmol使痛阈升高44％,其镇痛效应尚不及200nmol甲啡肽的作用(痛闻升高61％);注射甲七肽10-200nmol未见痛阈明显改变。注射亮啡肽或甲七肽抗体并不能对抗电针镇痛;注射甲七肽降解酶抑制剂Captopril 1000nmol也不能加强电针镇痛。这些资料说明,脊髓中的亮啡肽和甲七肽存痛觉调制中可能不起重要作用。     

LSK derived LSK- cells have a high apoptotic rate related to survival regulation of hematopoietic and leukemic stem cells

A balanced pool of hematopoietic stem cells (HSCs) in bone marrow is tightly regulated, and this regulation is disturbed in hematopoietic malignancies such as chronic myeloid leukemia (CML). The underlying mechanisms are largely unknown. Here we show that the Lin(-)Sca-1(+)c-Kit(-) (LSK(-)) cell population derived from HSC-containing Lin(-)Sca-1(+)c-Kit(+) (LSK) cells has significantly higher numbers of apoptotic cells. Depletion of LSK cells by radiation or the cytotoxic chemical 5-fluorouracil results in an expansion of the LSK(-) population. In contrast, the LSK(-) population is reduced in CML mice, and depletion of leukemia stem cells (LSCs; BCR-ABL-expressing HSCs) by deleting Alox5 or by inhibiting heat shock protein 90 causes an increase in this LSK(-) population. The transition of LSK to LSK(-) cells is controlled by the Icsbp gene and its downstream gene Lyn, and regulation of this cellular transition is critical for the survival of normal LSK cells and LSCs. These results indicate a potential function of the LSK(-) cells in the regulation of LSK cells and LSCs.     

Genetic consequences of a century of protection: serial founder events and survival of the little spotted kiwi (Apteryx owenii)

We present the outcome of a century of post-bottleneck isolation of a long-lived species, the little spotted kiwi (Apteryx owenii, LSK) and demonstrate that profound genetic consequences can result from protecting few individuals in isolation. LSK were saved from extinction by translocation of five birds from South Island, New Zealand to Kapiti Island 100 years ago. The Kapiti population now numbers some 1200 birds and provides founders for new populations. We used 15 microsatellite loci to compare genetic variation among Kapiti LSK and the populations of Red Mercury, Tiritiri Matangi and Long Islands that were founded with birds from Kapiti. Two LSK native to D''Urville Island were also placed on Long Island. We found extremely low genetic variation and signatures of acute and recent genetic bottleneck effects in all four populations, indicating that LSK have survived multiple genetic bottlenecks. The Long Island population appears to have arisen from a single mating pair from Kapiti, suggesting there is no genetic contribution from D''Urville birds among extant LSK. The N_e/N_C ratio of Kapiti Island LSK (0.03) is exceptionally low for terrestrial vertebrates and suggests that genetic diversity might still be eroding in this population, despite its large census size.     

The positive regulatory effect of TGF-beta2 on primitive murine hemopoietic stem and progenitor cells is dependent on age, genetic background, and serum factors

TGF-beta is considered a negative regulator of hemopoietic stem and progenitor cells. We have previously shown that one TGF-beta isoform, TGF-beta2, is, in fact, a positive regulator of murine hemopoietic stem cell function in vivo. In vitro, TGF-beta2, but not TGF-beta1 and TGF-beta3, had a biphasic dose response on the proliferation of purified lin-Sca1(++)kit(+) (LSK) cells, with a stimulatory effect at low concentrations, which was subject to mouse strain-dependent variation. In this study we report that the stimulatory effect of TGF-beta2 on the proliferation of LSK cells increases with age and after replicative stress in C57BL/6, but not in DBA/2, mice. The age-related changes in the TGF-beta2 effect correlated with life span in BXD recombinant strains. The stimulatory effect of TGF-beta2 on the proliferation of LSK cells requires one or more nonprotein, low m.w. factors present in fetal calf and mouse sera. The activity of this factor(s) in mouse serum increases with age. Taken together, our data suggest a role for TGF-beta2 and as yet unknown serum factors in the aging of the hemopoietic stem cell compartment and possibly in organismal aging.     

造血干细胞全标记红色和绿色荧光转基因小鼠的筛选

目的对五种荧光转基因小鼠造血干细胞中的荧光标记细胞进行分析,筛选造血干细胞全标记红色和绿色荧光转基因小鼠,为造血干细胞分化机制体内示踪研究提供理想的动物模型。方法采用活体荧光影像系统对两种红色荧光转基因小鼠品系C57BL/6J-TgN（CAG-DsRed-1和CAG-DsRed-2）ZLFILAS和三种绿色荧光转基因小鼠品系C57BL/6J-TgN（CAG-EGFP-1、CAG-EGFP-2和CAG-EGFP-3）ZLFILAS的荧光标记进行比较;采用流式细胞术检测各转基因小鼠的骨髓lin（-）c-kit（＋）Sca-1＋（LSK）造血干细胞荧光标记细胞比率,根据标记比率筛选造血干细胞全标记红色和绿色荧光转基因小鼠。结果活体荧光影像分析表明转基因小鼠均系统性表达红色或绿色荧光。流式细胞术检测表明LSK造血干细胞中高度表达红色和绿色荧光,其中,C57BL/6J-TgN（CAG-DsRed-1）ZLFILAS和C57BL/6J-TgN（CAG-EGFP-1）ZLFILAS的造血干细胞全部为荧光标记细胞。结论筛选获得在造血干细胞中全标记的红色和绿色荧光转基因小鼠,可为造血干细胞体内研究提供有效示踪工具。     

Lineage(-)Sca1+c-Kit(-)CD25+ cells are IL-33-responsive type 2 innate cells in the mouse bone marrow

IL-33 promotes type 2 immune responses, both protective and pathogenic. Recently, targets of IL-33, including several newly discovered type 2 innate cells, have been characterized in the periphery. In this study, we report that bone marrow cells from wild-type C57BL/6 mice responded with IL-5 and IL-13 production when cultured with IL-33. IL-33 cultures of bone marrow cells from Rag1 KO and Kit(W-sh/W-sh) mice also responded similarly; hence, eliminating the possible contributions of T, B, and mast cells. Rather, intracellular staining revealed that the IL-5- and IL-13-positive cells display a marker profile consistent with the Lineage(-)Sca-1(+)c-Kit(-)CD25(+) (LSK(-)CD25(+)) cells, a bone marrow cell population of previously unknown function. Freshly isolated LSK(-)CD25(+) cells uniformly express ST2, the IL-33 receptor. In addition, culture of sorted LSK(-)CD25(+) cells showed that they indeed produce IL-5 and IL-13 when cultured with IL-33 plus IL-2 and IL-33 plus IL-7. Furthermore, i.p. injections of IL-33 or IL-25 into mice induced LSK(-)CD25(+) cells to expand, in both size and frequency, and to upregulate ST2 and α(4)β(7) integrin, a mucosal homing marker. Thus, we identify the enigmatic bone marrow LSK(-)CD25(+) cells as IL-33 responsive, both in vitro and in vivo, with attributes similar to other type 2 innate cells described in peripheral tissues.     

Specific overexpression of SIRT1 in mesenchymal stem cells rescues hematopoiesis niche in BMI1 knockout mice through promoting CXCL12 expression

Osteoblastic lineage cells (OBCs) are bone-building cells and essential component of hematopoietic niche, but mechanisms whereby bone-building and hematopoiesis-supportive activities of OBCs could be regulated simultaneously remain largely unknown. Here we found that B cell-specific Moloney murine leukemia virus integration site 1 (Bmi1) was involved in such a co-regulatory mechanism. In this study, we first found that, accompanied with marked decline of osteogenic activity, the hematopoietic niche in Bmi1 knockout (KO) mice was severely impaired and manifested as CXCL12 expression falls and LSK homing failure; however, intratibial injection with CXCL12 effectively facilitated LSK accumulation in bone marrow of Bmi1 KO mice. To try to rescue these defects in Bmi1 KO mice, we generated Bmi1^KO/Sirt1^Tg (KO-TG) double mutant mice with Sirt1 specific overexpression in mesenchymal progenitor cells (MPCs) in Bmi1 KO mice, and our data showed that KO-TG mice had significantly increased bone-building activity, elevated Cxcl12 expression by MPCs, increased LSK homing and expanded LSK pool in bone marrow compared to Bmi1 KO mice. Of note, similar improvements in KO-TG mice were observed in Bmi1 KO mice fed with dietary resveratrol, an established Sirt1 activator, comparing with KO control mice. Therefore, pharmacologic activation of Bmi1/Sirt1 signaling pathway could simultaneously promote bone-building and hematopoiesis-supportive activities of OBCs.