Response ofPhloeotribus scarabaeoides (Coleoptera,Scolytidae) to ethylene in an olfactometer

The role of ethylene, pure or in formulation, in the colonization behaviour of the olive bark beetle,Phloeotribus scarabaeoides (Coleoptera, Scolytidae) has been investigated in the laboratory. Ethylene has been found to be attractive in both sexes; the formulation ethrel 48 was active in an olfactometer up to several months. Ethylene, whose concentration varies with the developmental stage or the condition of the tree or its wood, may play an important role in the primary attraction of these scolytids to their host.     

The influence of prostacyclin (PGI2) on contractile properties of isolated right ventricle of rat heart

The mechanism of the positive inotropic effect of prostacyclin (PGI₂) (2.6×10^?6 mol/l) on the isolated right ventricle of rat heart was studied. Our results show that the positive inotropic effect of prostacyclin is produced indirectly through beta adrenoceptors and slow Ca²⁺ channels, because blockade of slow Ca²⁺ channels with verapamil (10^?6 mol/l) and beta adrenoceptors with propranolol (10^?6 mol/l) abolishes this effect. Alpha adrenoceptors do not mediate the action of PGI₂.     

Can purchasing power parity help forecast the dollar?

This paper examines the information on future exchange rate movements provided by the doctrine of purchasing power parity (PPP). Previous research has studied this issue by analyzing the time-series properties of period-by-period levels of, or changes in, exchange rates. In contrast, the present study focuses on the durations of periods in which exchange rates deviate from their PPP levels. If PPP provides information about future exchange rate movements, these durations should exhibit positive duration dependence. That is, the probability of returning to PPP levels should increase as the period of deviation increases. Parametric hazard functions estimated using data from eighteen countries provide no evidence of positive duration dependence. These results are robust to alternative definitions of PPP and to alternative functional specifications. While exchange rates take prolonged swings away from their PPP levels and then eventually return, these movements apparently constitute Monte Carlo cycles in which, at any point in time, the probability of moving back toward PPP is the same as the probability of moving farther away. Thus, PPP provides no useful information on future exchange rate changes, a result consistent with market efficiency.     

龙门山茂汶─汶川变质带构造特征研究

龙门山中段茂汶─汶川韧性剪切带中可见到绿片岩相到角闪岩相的古生界。该地的巴罗型中压变质相相当于松潘—甘孜褶皱带中地壳的绿泥石带，构成了北东—南西向的茂汶—汶川变质带。雪隆包花岗岩体正位于该变质带的中心部位。三次韧性变形作用（Ｄ１～Ｄ３）造就了印支褶皱带，并在三叠纪末末形成了松潘—甘孜褶皱带。Ｄ１变形作用为北东—南西向的挤压作用和冲断作用，形成了大型的等斜褶皱，使古生界缩短和加厚。在持续的Ｄ２北京—南西向挤压作用下，松潘—甘孜褶皱带和稳定的扬子克拉通之间的差异应变由茂汶—汶川剪切带中非同轴左旋剪切作用所容纳。雪隆包花岗岩体是在Ｄ２变形作用的晚期侵入到剪切带的。产生蓝晶石的变质条件也是在Ｄ２或Ｄ２变形作用后出现的。Ｄ３变形作用为北西—南东向挤压，在局部地方形成糜棱岩状的道冲剪切带。这些特征与绿泥石退变质作用有关，揭示出在Ｄ３变形期间茂汶—汶川变质带有较大幅度的隆升。尽管雪隆包岩体在空间上与茂汶—汶川变质带有关，但作者认为其变质作用是岩层加厚引起的热作用重新达到平衡的产物，而不是由侵入作用引起的热接触变质作用。然而，与岩浆作用伴生的高温和活动性流体仍是产生Ｄ３局部变形和雪隆包岩体隆升的原因，这也是局部出现角闪告相     

贵州植物园珍稀濒危蕨类植物

本文介绍引种自贵州各地及我国华中、华东和华东的贵州植物园内的珍稀濒危蕨类植物。除列表表示来源、现状等情况外，还对桫椤Ａｌｓｐｈｉｌａ ｓｐｉｎｕｌｏｓａ （Ｈｏｏｋ）Ｔｒｙｏｎ，扇蕨Ｎｅｏｃｈｅｉｒｏｐｔｅｒｉｓ ｐｌａｍａｔｏｐｅｄａｔａ （Ｂａｋ．）Ｃｈｓｉｓｔ，宽叶水韭Ｉｓｏｅｔｅｓ ｊａｐｏｎｉｃａ Ａ．Ｂｒ．，中华水韭Ｉ．ｓｉｎｅｎｓｉｓ Ｐａｌｍｅｒ和截基盾蕨Ｎｅｏｌｅｐｉｓｏｒｕｓ     

铬酸钒为基的PTC陶瓷的研究

本文使用ＳＥＭ、ＥＤＳ、ＥＡＳ、ＸＲＤ和电阻率测量技术，研究了工艺参数和加入（Ｃｏ，Ｆｅ２Ｏ３）对ＰＴＣ（Ｖ１－ｘ，Ｃｒｘ）２Ｏ３陶瓷的显微结构和电性能的影响。实验结果表明，为了制造优良性能、高可靠的热敏电阻器，必须精确控制陶瓷组份和工艺。引人象Ｃ。这样的添加物是重要的，它主要以金属形式分布在基体中，同时发现添加物对试样致密度和电性能的影响也是有益的。     

燃烧室偶合系统不稳定传热的数值分析

本文在轴对称不稳定热传导有限元分析模型的基础上,提出了一个内燃机燃烧室的活塞与缸套偶合系统的不稳定传热数值分析模型。该模型考虑了在燃气与边界的对流和热幅射非线性热交换条件下运动着的活塞、活塞环、缸套和润滑油膜之间在传热过程中的相互作用和影响,可以预测上述系统各部分的温度波动分布、瞬态温度场以及瞬态热流分布。     

Monoclonal antibody and ligand binding sites of the T cell erythrocyte receptor (CD2)

The human T cell erythrocyte receptor (CD2 antigen) allows thymocytes and mature T cells to adhere to thymic epithelium and target cells through a cell surface protein, LFA-3 (refs 1-6). Monoclonal antibodies recognizing CD2 can either block adhesion or, in certain combinations, induce an antigen-independent T cell activation. We have identified the binding sites for 16 monoclonal antibodies against CD2 by a rapid and generally applicable mutational analysis. The binding sites fall in three discrete regions: antibodies that participate in activation and block erythrocyte adhesion bind to the first region; antibodies that block adhesion bind to the second region; and antibodies that participate in activation but do not block adhesion bind to the third region. A large number of mutations selected for loss of antibody reactivity in the first two regions also weaken the CD2-LFA-3 interaction. Good agreement was observed between mutational lesions blocking LFA-3 binding and lesions blocking binding by activating antibodies, which supports the view that such antibodies induce T cell activation by mimicking the effect of LFA-3 binding. CD2 sequences that participate in LFA-3 binding correspond to immunoglobulin variable region hypervariable sequences when the homologous domains are aligned.     

Cloning of decay-accelerating factor suggests novel use of splicing to generate two proteins

Decay-accelerating factor (DAF), a glycoprotein that is anchored to the cell membrane by phosphatidylinositol, binds activated complement fragments C3b and C4b, thereby inhibiting amplification of the complement cascade on host cell membranes. Here, we report the molecular cloning of human DAF from HeLa cells. Analysis of DAF complementary DNAs revealed two classes of DAF messenger RNA, one apparently derived from the other by a splicing event that causes a coding frameshift near the C terminus. The apparent 'intron' sequence contains an Alu family member and encodes contiguous protein sequence. Two DAF proteins are therefore possible, having divergent C-terminal domains which differ in their hydrophobicity. Both mRNAs are found on polysomes, suggesting that both are translated. We propose that the major (90%) spliced DAF mRNA encodes membrane-bound DAF whereas the minor (10%) unspliced DAF mRNA may encode secreted DAF and we present expression data supporting this. The deduced DAF sequence contains four repeating units homologous to a consensus repeat found in a recently described family of complement proteins.     

Suppression of in vitro haematopoiesis following human immunodeficiency virus infection

Viral infections are frequently associated with haematological disorders. Abnormalities including leukopenia, anaemia and thrombocytopenia are commonly observed in patients with the acquired immune deficiency syndrome (AIDS) or the AIDS-related complex (ARC). The underlying cause of these haematological abnormalities is poorly understood. We report here that bone marrow progenitors isolated from AIDS or ARC patients are responsive to recombinant human granulocyte-macrophage colony stimulating factor (rGM-CSF) and recombinant erythropoietin. Antibodies present in the serum of patients infected with the human immunodeficiency virus (HIV), however, could suppress the growth of these progenitors, but not the growth of progenitors from HIV seronegative controls. A component of this immune-mediated suppression appears to be antibodies directed towards the envelope glycoprotein (gp120) of HIV.