Feasibility study of an explosive gun

Feasibility of high performance, explosively driven device, and calculations for deformable piston light gas gu

Domains of invasion organelle proteins from apicomplexan parasites are homologous with the Apple domains of blood coagulation factor XI and plasma pre-kallikrein and are members of the PAN module superfamily

AbstractMicronemes are specialised organelles, found in all apicomplexan parasites, which secrete molecules that are essential for parasite attachment to and invasion of host cells. Regions of several microneme proteins have sequence similarity to the Apple domains (A-domains) of blood coagulation factor XI (FXI) and plasma pre-kallikrein (PK). We have used mass spectrometry on a recombinant-expressed, putative A-domain from the microneme protein EtMIC5 from Eimeria tenella, to demonstrate that three intramolecular disulphide bridges are formed. These bridges are analogous to those that stabilise A-domains in FXI and PK. The data confirm that the apicomplexan domains are structural homologues of A-domains and are therefore novel members of the PAN module superfamily, which also includes the N-terminal domains of members of the plasminogen/hepatocyte growth factor family. The role of A-domains/PAN modules in apicomplexan parasites is not known, but their presence in the microneme suggests that they may be important for mediating protein–protein or protein–carbohydrate interactions during parasite attachment and host cell invasion

Laser frequency stabilization to a single ion

A fundamental limit to the stability of a single-ion optical frequency standard is set by quantum noise in the measurement of the internal state of the ion. We discuss how the interrogation sequence and the processing of the atomic resonance signal can be optimized in order to obtain the highest possible stability under realistic experimental conditions. A servo algorithm is presented that stabilizes a laser frequency to the single-ion signal and that eliminates errors due to laser frequency drift. Numerical simulations of the servo characteristics are compared to experimental data from a frequency comparison of two single-ion standards based on a transition at 688 THz in 171Yb+. Experimentally, an instability sigma_y(100 s)=9*10^{-16} is obtained in the frequency difference between both standards.Comment: 15 pages, 5 figures, submitted to J. Phys.

Unique Mass Texture for Quarks and Leptons

Texture specific quark mass matrices which are hermitian and hierarchical are examined in detail . In the case of texture 6 zeros matrices, out of sixteen possibilities examined by us, none is able to fit the low energy data (LED), for example, $V_{us} = 0.2196 \pm 0.0023$, $V_{cb} = 0.0395 \pm 0.0017$, $\frac{V_{ub}}{V_{cb}} = 0.08 \pm 0.02$, $V_{td}$ lies in the range $0.004 - 0.013$ (PDG). Similarly none of the 32 texture 5 zeros mass matrices considered is able to reproduce LED. In particular, the latest data from LEP regarding $|V_{ub}|/|V_{cb}|(=0.093\pm0.016)$ rules out all of them. In the texture 4 zeros case, we find that there is a unique texture structure for $U$ and $D$ mass matrices which is able to fit the data.Comment: 12 pages, LaTeX,some changes in the references,minor changes in the text,to appear in Phys Rev D(Rapid communications

Counterterrorism Killings and Provisional IRA Bombings, 1970-1998

Counterterrorism strategies involving the killing of terrorists are a prominently used but controversial practice. Proponents argue that such strategies are useful tools for reducing terrorist activity, while critics question their effectiveness. This paper provides empirical insight into this strategy by conducting a series of negative binomial regression and Tobit estimations of the impact of killing Provisional Irish Republican Army (PIRA) terrorists as well as members of the Catholic community on counts of PIRA bombings and targeting activity in Northern Ireland for the period 1970-1998. We consider the impact of discriminate and indiscriminate killings (where only PIRA militants are killed versus those in which both militants and civilians are also killed) on subsequent PIRA IED attacks. Our findings illustrate that while total and discriminate counterterrorism killings have little to no effect on PIRA IED attacks, indiscriminate counterterrorism killings increased PIRA bombings overall and prompted the Provisional IRA to specifically target civilians in IED events. We conclude by discussing the scholarly and policy implications of these findings

Calcium binding activity of the epidermal growth factor-like domains of the apicomplexan microneme protein EtMIC4

Microneme proteins are secreted from apicomplexan parasites during invasion of host cells and they play crucial roles in parasite-host cell adhesion. EtMIC4 is a 240 kDa transmembrane protein from Eimeria tenella that contains 31 tandemly arranged epidermal growth factor (EGF), like repeats within its extracellular domain. The majority of these repeats have calcium binding (cb) consensus sequences. Little is known about cbEGFs in apicomplexan parasites but their presence in microneme proteins suggests that they may contribute to parasite-host interactions. To investigate the potential role of cbEGFs we have expressed and correctly refolded a cbEGF triplet from EtMIC4 (cbEGF7-9) and demonstrated that this triplet binds calcium. Circular dichroism spectroscopic analysis of cbEGF7-9 demonstrates that the molecule undergoes a gradual change in conformation with increasing levels of calcium. In the presence of calcium, the triplet becomes resistant to proteolytic degradation by a variety of proteases, a characteristic feature of cbEGF repeats from higher eukaryotic proteins, such as fibrillin, suggesting that calcium binding induces the formation of a rigid conformation. Moreover, mass spectrometric mapping of the cleavage sites that are protected by calcium shows that these sites are located both close to and distant from the calcium binding sites, indicating that protection is not due to steric hindrance by calcium ions, but rather due to the overall conformation adopted by the triplet in the presence of calcium. Thus, the tandemly-arranged cbEGF repeats within EtMIC4 provide a mechanism whereby, in the calcium-rich extracellular environment, the molecule could adopt a protease-resistant, rigid structure that could favour its interaction with host cell ligands

LENS® and SFF: Enabling Technologies for Optimized Structures

Optimized, lightweight, high-strength structures are needed in many applications from aerospace to automotive. In pursuit of such structures, there have been proposed analytical solutions and some specialized FEA solutions for specific structures such as automobile frames. However, generalized 3D optimization methods have been unavailable for use by most designers. Moreover, in the cases where optimized structural solutions are available, they are often hollow, curving, thin wall structures that cannot be fabricated by conventional manufacturing methods. Researchers at Sandia National Laboratories and the University of Rhode Island teamed to solve these problems. The team has been pursuing two methods of optimizing models for generalized loading conditions, and also has been investigating the methods needed to fabricate these structures using Laser Engineered Net Shaping™ (LENS®) and other rapid prototyping methods. These solid freeform fabrication (SFF) methods offer the unique ability to make hollow, high aspect ratio features out of many materials. The manufacturing development required for LENS to make these complex structures has included the addition of rotational axes to Sandia’s LENS machine bringing the total to 5 controlled axes. The additional axes have required new efforts in process planning. Several of the unique structures that are only now possible through the use of SFF technology are shown as part of the discussion of this exciting new application for SFF.Mechanical Engineerin

Foreshadowing targeted violence: Assessing leakage of intent by public mass murderers

The idea that identifiable behaviors presage violence is a core concept in the threat assessment literature. Especially meaningful from an operational perspective is “leakage”, which concerns whether offenders intentionally or unintentionally reveal insights into their thoughts or feelings that suggest impending targeted violence. Previous research has generally been limited to assessing the prevalence of leakage in various offender populations. The present study more thoroughly describes leakage in a sample of 115 public mass murderers in the U.S. whose activities took place between 1990 and 2014. We disaggregate leakage into three distinct forms (written statements, verbal statements to the public, verbal statements to family/friends), and examine these in relation to theorized correlates of leakage. The only significant predictor of leakage we found is the presence of a grievance, specifically a grievance against a person or entity, as opposed to a grievance against a category of people or a grievance against an idea, movement or religion. We discuss implications of these results as well as directions for future research