Trail-following pheromones of the rhinotermitidae: Approaches to their authentication and specificity

A method for determining the authenticity of subterranean termite trail pheromones is suggested and utilized to verify the presence of trail pheromones inReticulitermes virginicus, R. flavipes, andR. tibialis. In addition, a possible trail pheromone has been demonstrated forCoptotermes formosanus. A choice bioassay method shows that the above trail pheromones are species specific.     

2003年采购指南

现在名牌笔记本电脑也卖到1000美元以下了,你也该想想你的下一台PC是否应该是笔记本     

Reward,persuasion, and the Sokal Hoax: A study in citation identities

A citation identity is a list of an author's citees ranked by how frequently that author has cited them in publications covered by the Institute for Scientific Information. The same Dialog software that creates identities can simultaneously show the overall citation counts of citees, which indicate their reputations. Using identities for 28 authors in several disciplines of science and scholarship, I show that the reputational counts of their citees always have an approximately log-normal distribution: citations to very famous names are roughly balanced by citations to obscure ones, and most citations go to authors of middling reputation. These results undercut claims by constructivists that the main function of citation is to marshal “big-name” support for arguments at the expense of crediting lesser-known figures. The results are better explained by Robert K. Merton's norm of universalism, which holds that citers are rewarding use of relevant intellectual property, than by the constructivists' particularism, which holds that citers are trying to persuade through manipulative rhetoric. A universalistic citation pattern appears even in Alan Sokal's famous hoax article, where some of his citing was deliberately particularistic. In fact, Sokal's basic adherence to universalism probably helped his hoax succeed, which suggests the strength of the Mertonian norm. In specimen cases, the constructivists themselves are shown as conforming to it. This revised version was published online in June 2006 with corrections to the Cover Date.     

Romantic versus realistic views of psychology.

Comments on the article by R. J. Sternberg and E. L. Grigorenko (see record 2001-10045-001), which described an approach to psychology ("unified psychology") that is a multiparadigmatic, multidisciplinary, and integrated study of psychological phenomena through converging operations. According to the present author, Sternberg and Grigorenko ignored fundamental methodological differences within the discipline when they developed their concept of unified psychology. In addition, Sternberg and Grigorenko's conception of a unified psychology was achieved by extending the meanings of converging operations (W. R. Garner et al, 1956) and paradigm (T. S. Kuhn, 1970) beyond their original intent. Sternberg and Grigorenko flagrantly ignored striking differences among contemporary psychologists' criteria for truth or verisimilitude. Instead of viewing psychology within the context of converging operations and paradigms and holding the amorphous conception that psychologists "need adhere to no particular set of methods, to no particular field, and to no particular paradigm," psychologists should consider an alternative, more direct approach: explicitly stating both the nature of the psychological phenomena to be studied and as well as their intended mode of explanation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unraveling Membrane Perturbations Caused by the Bacterial Riboregulator Hfq

Hfq is a pleiotropic regulator that mediates several aspects of bacterial RNA metabolism. The protein notably regulates translation efficiency and RNA decay in Gram-negative bacteria, usually via its interaction with small regulatory RNAs. Previously, we showed that the Hfq C-terminal region forms an amyloid-like structure and that these fibrils interact with membranes. The immediate consequence of this interaction is a disruption of the membrane, but the effect on Hfq structure was unknown. To investigate details of the mechanism of interaction, the present work uses different in vitro biophysical approaches. We show that the Hfq C-terminal region influences membrane integrity and, conversely, that the membrane specifically affects the amyloid assembly. The reported effect of this bacterial master regulator on membrane integrity is discussed in light of the possible consequence on small regulatory RNA-based regulation.     

Characterization of a Cutibacterium acnes Camp Factor 1-Related Peptide as a New TLR-2 Modulator in In Vitro and Ex Vivo Models of Inflammation

Cutibacterium acnes (C. acnes) has been implicated in inflammatory acne where highly mutated Christie–Atkins–Munch–Petersen factor (CAMP)1 displays strong toll like receptor (TLR)-2 binding activity. Using specific antibodies, we showed that CAMP1 production was independent of C. acnes phylotype and involved in the induction of inflammation. We confirmed that TLR-2 bound both mutated and non-mutated recombinant CAMP1, and peptide array analysis showed that seven peptides (A14, A15, B1, B2, B3, C1 and C3) were involved in TLR-2 binding, located on the same side of the three-dimensional structure of CAMP1. Both mutated and non-mutated recombinant CAMP1 proteins induced the production of C-X-C motif chemokine ligand interleukin (CXCL)8/(IL)-8 in vitro in keratinocytes and that of granulocyte macrophage-colony stimulating factor (GM-CSF), tumor necrosis factor (TNF)-α, IL-1β and IL-10 in ex vivo human skin explants. Only A14, B1 and B2 inhibited the production of CXCL8/IL-8 by keratinocytes and that of (GM-CSF), TNF-α, IL-1β and IL-10 in human skin explants stimulated with rCAMP1 and C. acnes. Following pretreatment with B2, RNA sequencing on skin explants identified the 10 genes displaying the strongest differential expression as IL6, TNF, CXCL1, CXCL2, CXCL3, CXCL8, IL-1β, chemokine ligand (CCL)2, CCL4 and colony stimulating factor (CSF)2. We, thus, identified a new CAMP1-derived peptide as a TLR-2 modulator likely to be a good candidate for clinical evaluation.     

Fretting wear behavior of bulk amorphous steel

Fretting wear of Fe₄₁Co₇Cr₁₅Mo₁₄C₁₅B₆Y₂ bulk metallic glass (BMG) was investigated using the ball-on-disc measurement. The wear behaviors of the samples roughly follow the classical Archard wear law at room temperature. The influence of temperature on wear resistance (R_w) and microhardness (H_v) was evaluated. A good linear correlation was found between R_w and H for the Fe-based BMG. The results indicate that the hardness softening is responsible for the decrease of R_w at high temperature. The wear mechanism at high temperature was elucidated through the analysis of oxidation and debris morphology on the wear scar. Compared with traditional crystalline steels and other non-ferrous metal-based glassy alloys, the bulk amorphous steel shows higher wear resistance and hardness, which promotes its application as an advanced engineering material.     

Blood flow in the rabbit aortic arch and descending thoracic aorta

The distribution of atherosclerotic lesions within the rabbit vasculature, particularly within the descending thoracic aorta, has been mapped in numerous studies. The patchy nature of such lesions has been attributed to local variation in the pattern of blood flow. However, there have been few attempts to model and characterize the flow. In this study, a high-order continuous Galerkin finite-element method was used to simulate blood flow within a realistic representation of the rabbit aortic arch and descending thoracic aorta. The geometry, which was obtained from computed tomography of a resin corrosion cast, included all vessels originating from the aortic arch (followed to at least their second generation) and five pairs of intercostal arteries originating from the proximal descending thoracic aorta. The simulations showed that small geometrical undulations associated with the ductus arteriosus scar cause significant deviations in wall shear stress (WSS). This finding highlights the importance of geometrical accuracy when analysing WSS or related metrics. It was also observed that two Dean-type vortices form in the aortic arch and propagate down the descending thoracic aorta (along with an associated skewed axial velocity profile). This leads to the occurrence of axial streaks in WSS, similar in nature to the axial streaks of lipid deposition found in the descending aorta of cholesterol-fed rabbits. Finally, it was observed that WSS patterns within the vicinity of intercostal branch ostia depend not only on local flow features caused by the branches themselves, but also on larger-scale flow features within the descending aorta, which vary between branches at different locations. This result implies that disease and WSS patterns in the vicinity of intercostal ostia are best compared on a branch-by-branch basis.     

On Homogeneous Nucleation of Dislocation Loops in Nanocrystalline Materials

In this article, we readdress the question of homogeneous nucleation of dislocation loops in the context of nanocrystalline materials. In this case, the commonly adopted assumption of an infinite medium is no longer valid, and image forces on dislocations must be accounted for in the analysis. An additional energy term associated with the presence of finite boundaries may act to promote homogeneous nucleation and growth of dislocation loops. Based on a simplified consideration of a circular dislocation loop in a spherical nanoparticle or nanosized grain in a polycrystal, energy calculations are carried out to estimate the activation energy for homogeneous nucleation of a dislocation loop in such a system. Two different cases are considered: (1) a single nanoparticle and (2) a grain in a polycrystalline nanomaterial. Based on simulations for aluminum, it is shown that this mechanism may be plausible in both cases, albeit only for small particles and grains in the nanometer range.     

Cell design in bacteria as a convex optimization problem

In this paper, we investigate the prediction of the cell composition of bacteria with respect to their medium. By modeling the bacterium as an interconnection of subsystems, the problem is written as a non-smooth convex optimization problem equivalent to a Linear Programming feasibility problem. We then obtain a new method, called Resource Balance Analysis (RBA), predicting the distribution of the available resources in the medium among the various cellular subsystems. Beyond its predictive capability, the proposed approach grasps some fundamental aspects of the bacterium physiology by including a refined model. This method reveals the existence of an intrinsic bottleneck in the system resource distribution of the bacterium, leading to the existence of a structural limitation of its growth rate which can be predicted. RBA is also able to predict the configuration of the metabolic network for a given medium at steady-state regimen which nicely fits the available experimental results for the gram-positive model bacterium Bacillus subtilis.