X-Ray Absorption and Scattering by Interstellar Grains

Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. An open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), is presented that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.Comment: 32 pages, 15 figure

Terrorism in History

The central question addressed in this collection is: in what circumstances did terrorism act as a "driver of history," exerting a major impact on international and national events, and why was it able to do so? To answer this question, this article focuses on three levels of analysis: first, using the assassination of the Archduke Franz Ferdinand in 1914 as a case study, it explores terrorism’s monumental power to change the course of history. The second, which takes as its reference point the case of the Fenian dynamiters’ campaign in Britain during the 1880s, examines terrorism as a tactical weapon that achieves profound changes in governmental organization and policy to counter this menace. Finally, it discusses terrorism as a strategic force, re-calibrating international politics and affairs, and catapulting to prominence (and to an extent, power) hitherto unknown or inconsequential movements, such as the Palestinian fedayeen after the 1967 Six Day War. Each of these offers an important lesson from the past for our understanding of terrorism today, namely, how what may appear to be completely new and novel in the present often has a significantly relevant historical precedent. Indeed, all three cases presaged some later, important development in terrorist tactics or strategy: in the first case, the emergence of state-sponsored terrorism; in the second, attacks on subways (in London) and other mass transit, that also led to the formation of new security forces in response to the threat; and third, the "cult of the insurgent" that has enormous resonance in Iraq, with bin Laden, and in America’s war on terrorism today

The bombing of The King David Hotel, July 1946

On 22 July 1946, the Irgun Zvai Le’umi (National Military Organization), a Jewish terrorist organization opposed to Britain’s continued rule of Palestine, bombed Jerusalem’s King David Hotel. The incident has always been controversial given the fact that the facility was not an ordinary hotel, but also the nerve center of British rule over that country — housing its military headquarters, intelligence stations, and government secretariat. Further, at the time it was claimed that warnings were issued to evacuate the hotel that British officials callously ignored. This article addresses three key three questions surrounding the bombing: Was the King David Hotel in fact a legitimate military target? Were warnings in fact given to evacuate the hotel? And, if so, why wasn’t the hotel evacuated? The answers, while critical in reaching an accurate accounting and factual understanding of a highly controversial event, interestingly also shed light on the efficacy and morality of terrorism as an instrument of national liberation and agent of political change.PostprintPeer reviewe

Jewish terrorist activities and the British government in Palestine, 1939-1947

From 1939 to 1947 two Jewish terrorist organizations, the Irgun Zvai Leumi and the Lohamei Herut Israel (known to Jews by its Hebrew acronym, Lehi, and to the British as "The Stern Gang") challenged Britain's rule over Palestine. Those eight years began with the publication of the White Paper in May 1939 and ended in September 1947 with the decision taken by the British Government to surrender its League of Nations Mandate and withdraw from Palestine. This thesis examines the influence that Jewish terrorist activities had on Britain's policy for Palestine and seeks to ascertain the role played by terrorism in that decision. Through an examination of British policy and the strategies employed by the British Army to defeat the terrorists, this study demonstrates why the British failed to reach either a military or a political settlement in Palestine. This failure can.be attributed both to the irreconcilable nature of Arab and Jewish claims to the country and the lack of a clear and consistent policy for Palestine on Britain's part. The situation was further aggravated by the weaknesses of the Palestine Police Force, the futile efforts of the Palestine Government to obtain the cooperation of the Jewish public against the terrorists and the debilitating effect of Jewish terrorist activities on the morale of the British soldier in Palestine. The search for a solution to the Palestine problem after World War II took place amid increasing terrorist violence in the country. As British authority in Palestine deteriorated, Britain's will to remain there dissolved. This thesis concludes that no single factor itself can be considered responsible for the decision to surrender the mandate and leave Palestine. At the same time, however, Jewish terrorist activities played an important--and even a decisive--role in the events that led to the termination of British rule over Palestine and the establishment of the State of Israel

Using bacterial biomarkers to identify early indicators of cystic fibrosis pulmonary exacerbation onset

Acute periods of pulmonary exacerbation are the single most important cause of morbidity in cystic fibrosis patients, and may be associated with a loss of lung function. Intervening prior to the onset of a substantially increased inflammatory response may limit the associated damage to the airways. While a number of biomarker assays based on inflammatory markers have been developed, providing useful and important measures of disease during these periods, such factors are typically only elevated once the process of exacerbation has been initiated. Identifying biomarkers that can predict the onset of pulmonary exacerbation at an early stage would provide an opportunity to intervene before the establishment of a substantial immune response, with major implications for the advancement of cystic fibrosis care. The precise triggers of pulmonary exacerbation remain to be determined; however, the majority of models relate to the activity of microbes present in the patient's lower airways of cystic fibrosis. Advances in diagnostic microbiology now allow for the examination of these complex systems at a level likely to identify factors on which biomarker assays can be based. In this article, we discuss key considerations in the design and testing of assays that could predict pulmonary exacerbations