Constraining cometary ejection models from meteor storm observations

Modelling and observations of the Leonids have shown that maxima in the meteor storm activity can be identified as due to particles released from the comet during certain perihelion passages. If the particles originating from a certain perihelion passage can be identified, the next obvious question to ask is what information can be gained about the ejection process of particles from a cometary nucleus. We have developed a method to calculate the set of all possible dust trajectories that reach the Earth at some given time. The method involves numerical integration of a few dust particles only and is applied to the Leonid activity in the year 2000. We show that particles of different sizes entering the Earth's atmosphere at the same time were released from the comet at different heliocentric distances. Therefore one has to make assumptions about the activity of the comet with heliocentric distance in order to derive the cometary mass distribution from an observed meteor mass distribution. However, we outline how lower limits on the ejection velocity of the observed particles can be derived

Community Organizing in Three South Side Chicago Communities: Leadership, Activities, and Prospects

This study identifies barriers facing groups and leaders in communities on the South Side of Chicago that limit not only their capacity for organizing but also their ability to attract resources for their work. The findings also provide key data on current activities at the grassroots level, with particular attention to groups and leaders that have the potential to expand the scope of their efforts to larger, community-based initiatives

The Carboxyl-Terminal Segment of Apolipoprotein A-V Undergoes a Lipid-Induced Conformational Change

Apolipoprotein (apo) A-V is a 343-residue, multidomain protein that plays an important role in regulation of plasma triglyceride homeostasis. Primary sequence analysis revealed a unique tetraproline sequence (Pro293-Pro296) near the carboxyl terminus of the protein. A peptide corresponding to the 48-residue segment beyond the tetraproline motif was generated from a recombinant apoA-V precursor wherein Pro295 was replaced by Met. Cyanogen bromide cleavage of the precursor protein, followed by negative affinity chromatography, yielded a purified peptide. Nondenaturing polyacrylamide gel electrophoresis verified that apoA-V(296-343) solubilizes phospholipid vesicles, forming a relatively heterogeneous population of reconstituted high-density lipoprotein with Stokes’ diameters\u3e17 nm. At the same time, apoA-V(296-343) failed to bind a spherical lipoprotein substrate in vitro. Far-UV circular dichroism spectroscopy revealed the peptide is unstructured in buffer yet adopts significant R-helical secondary structure in the presence of the lipid mimetic solvent trifluoroethanol (TFE; 50% v/v). Heteronuclear multidemensional NMR spectroscopy experiments were conducted with uniformly 15N- and 15N/13C-labeled peptide in 50% TFE. Peptide backbone assignment and secondary structure prediction using TALOSþ reveal the peptide adopts R-helix secondary structure from residues 309 to 334. In TFE, apoA-V(296-343) adopts an extended amphipathic R-helix, consistent with a role in lipoprotein binding as a component of full-length apoA-V

Nuclear Imminence in Contemporary Indo‐Pakistani Conflict

November of 2008 saw frightening attacks on India’s foreigners. Over the course of three days, hostages had been taken, hotels and restaurants in India’s busiest city of Mumbai were burned and English, American and Canadian citizens lay among the nearly 200 dead. Pakistani terrorists were arrested and held accountable for this act of brutality. However, it seemed that tensions had just begun. The upset of peace in Indo-Pakistani relations fuelled the international communities’ fear of a nuclear war between the two nations. This paper will address this concern and discover that such acts of terrorism do not reflect nuclear imminence due to tensions between the Indian and Pakistani states. However, they do reflect unrest within Indian and Pakistani civil society; a civil society that is both tied and fragmented by ethnic and religious identity. The fear of nuclear war in this historically conflicted region of South East Asia may aid in the plight for peace by forcing these states to accept international norms and treaties on nuclear proliferation

Front Matter

Front Matte

Efficiently Integrating Boolean Reasoning and Mathematical Solving

Many real-world problems require the ability of reasoning efficiently on formulae which are boolean combinations of boolean and unquantified mathematical propositions. This task requires a fruitful combination of efficient boolean reasoning and mathematical solving capabilities. SAT tools and mathematical reasoners are respectively very effective on one of these activities each, but not on both. In this paper we present a formal framework, a generalized algorithm and architecture for integrating boolean reasoners and mathematical solvers so that they can efficiently solve boolean combinations of boolean and unquantified mathematical propositions. We describe many techniques to optimize this integration, and highlight the main requirements for SAT tools and mathematicalsolvers to maximize the benefits of their integration

Bluetooth friendly names: bringing classic HCI questions into the mobile space

We explore the use of Bluetooth friendly names within the mobile space. Each Bluetooth-enabled device possesses a short string known as a 'friendly name' used to help identify a device to human users. In our analysis, we collected friendly names in use on 9,854 Bluetooth-enabled devices over a 7-month period. These names were then classified and the results analysed. We discovered that a broad range of HCI themes are applicable to the domain of Bluetooth friendly names, including previous work on personalisation, naming strategies and anonymity in computer mediated communication. We also found that Bluetooth is already being used as a platform for social interaction and communication amongst collocated groups and has moved beyond its original intention of file exchange

GPs' views on new national smoking cessation guidelines

Objectives: To assess GPs? views on recently published national smoking cessation guidelines that form the foundation of the government?s smoking cessation strategy.Design: Postal survey of a random sample of GPs. GPs were asked to judge the appropriateness, effectiveness and practicability of key recommendations for primary care in recent national smoking cessation guidelines.Setting: General practice, England and Wales.Subjects: 236 GPs, effective response rate: 62%.Results: Only 16% of GPs accepted that all the recommendations in the guidelines were appropriate; 43% accepted that it was appropriate to check the smoking status of known smokers when they visit the surgery and only 30% thought it was practicable to advise smokers to stop at every opportunity. However, 77% of GPs thought that they should provide assistance for smokers wanting to stop; 74% believed that they should refer smokers to specialist services if appropriate and a similar proportion (77%) believed that it was appropriate to recommend nicotine replacement. Conclusions: Recommendations that involved the GP being proactive in monitoring smoking status and advising smokers to stop were not widely supported. There was greater acceptance that GPs should assist smokers wanting to stop, either by recommending NRT or providing counselling or referral. It appears that GPs do not widely support those recommendations that would produce the greatest public health gains

A porous prolate-spheroidal model for ciliated micro-organisms

A fluid-mechanical model is developed for representing the mechanism of propulsion of a finite ciliated micro-organism having a prolate-spheroidal shape. The basic concept is the representation of the micro-organism by a prolate-spheroidal control surface upon which certain boundary conditions on the tangential and normal fluid velocities are prescribed. Expressions are obtained for the velocity of propulsion, the rate of energy dissipation in the fluid exterior to the cilia layer, and the stream function of the motion. The effect of the shape of the organism upon its locomotion is explored. Experimental streak photographs of the flow around both freely swimming and inert sedimenting Paramecia are presented and good agreement with the theoretical prediction of the streamlines is found