Search

Acquisition of X‐ray crystallographic data is always accompanied by structural degradation owing to the absorption of energy. The application of high‐fluency X‐ray sources to large biomolecules has increased the importance of finding ways to curtail the onset of X‐ray‐induced damage. A significant effort has been under way with the aim of identifying strategies for protecting protein structure. A comprehensive model is presented that has the potential to explain, both qualitatively and quantitatively, the structural changes induced in crystalline protein at ∼100 K. The first step is to consider the qualitative question: what are the radiation‐induced intermediates and expected end products? The aim of this paper is to assist in optimizing these strategies through a fundamental understanding of radiation physics and chemistry, with additional insight provided by theoretical calculations performed on the many schemes presented. [ABSTRACT FROM AUTHOR]

The article focuses on the legislators who served in the 101st–110th Congresses of the U.S. and discusses the legislative style of the Congress by focusing on the legislators' styles. Topics discussed include the styles that legislators represent in the Congress including district advocates, those who focus on the interest of the district they represent; ambitious entrepreneurs; and policy specialists.

As soon as the sovereign debt crisis began, it was widely understood that Germany’s response would dictate its ultimate resolution. Whereas the initial round of bailouts stabilized markets and preserved the Euro, the purpose of the second Greek bailout is less clear. We argue that the German government’s decision to support a second Greek bailout reflected domestic political calculations. While a bailout would involve short-term political costs, Merkel’s government also recognized the social and economic consequences of potential Greek default. In particular, a default entailed the prospect of a massive inflow of migrants from Southern Europe into Germany, which would have hurt labor markets and, in turn, could have cost Merkel’s coalition electoral support. To evaluate the political, economic, and social costs of the second Greek bailout, we use models of credit default swap spreads, studies of international migration, and research on vote intention. [ABSTRACT FROM AUTHOR]

We argue that bill cosponsorship in Congress represents an institutional arrangement that provides credibility to commitments of support. We predict that if cosponsorship fosters legislative deals, MCs will only rarely back out on their pledges to support a bill if it comes up for a floor vote, and when they do, these choices will reflect strategic calculations. Further, legislators who violate their cosponsorship agreements will face punishment from colleagues, compromising their ability to gain support for their own bills. We explore the causes and effects of MCs' choices to renege on a pledge by voting no on a bill for which they were a cosponsor, focusing on all cosponsorship decisions in the 101st-108th Houses. The results reveal that patterns of reneging and its consequences are consistent with the idea that cosponsorship functions as a commitment mechanism. [ABSTRACT FROM AUTHOR]

An understanding of charge transfer (CT) in DNA liesat the rootof assessing the risks and benefits of exposure to ionizing radiation.Energy deposition by high-energy photons and fast-charged particlescreates holes and excess electrons (EEs) in DNA, and the subsequentreactions determine the complexity of DNA damage and ultimately therisk of disease. Further interest in CT comes from the possibilitythat hole transfer, excess electron transfer (EET), or both in DNAmight be used to develop nanoscale circuits. To study EET in DNA,EPR spectroscopy was used to determine the distribution of EE trappingby oligodeoxynucleotides irradiated and observed at 4 K. Our resultsindicate that stretches of consecutive adenine bases on the same strandserve as an ideal conduit for intrastrand EET in duplex DNA at 4 K.Specifically, we show that A is an efficient trap for EE at 4 K if,and only if, the A strand of the duplex does not contain one of theother three bases. If there is a T, C, or G on the A strand, thentrapping occurs at T or C instead of A. This holds true for stretchesup to 32 A’s. Whereas T competes effectively against A forthe EE, it does not compete effectively against C. Long stretchesof T pass the majority of EE to C. Our results show that AT stretcheschannel EE to cytosine, an end point with significance to both radiationdamage and the photochemical repair of pyrimidine dimers. [ABSTRACT FROM AUTHOR]

Our lab investigated damage of DNA due to ionizing radiation using electron paramagnetic resonance (EPR). Through studies focused on one-electron-reduction of synthetic oligodeoxynucleotides containing only thymine and adenine, we discovered the significant presence of a contaminant in all samples. The contaminant was observed to have a reduction potential greater than that of thymine. In addition, the contaminant yielded a sharp EPR singlet when it was one-electron reduced that interfered with the distinctive doublet of one-electron reduced thymine. We determined that the contaminant contained a benzoyl group, a chemical used in to protect the amine group of adenine during oligodeoxynucleotide synthesis. Derivatives of benzoyl and 16 different oligomer sequences were prepared in a LiCl glass and studied using EPR after X-irradiating at 4K. This treatment selectively creates one-electron reduced radicals. Synthetic derivatives were used to develop an EPR benchmark of the benzoyl radical. Using this, along with the known spectra of one-electron reduced nucleobases, we performed component analysis of the EPR signal from each sample. This analysis revealed that 2–9% of adenines, in the commercially synthesized oligomers delivered to us, were left contaminated with benzoyl. We concluded that the presence of benzoyl is a potential source of error in a variety of experiments utilizing synthesized oligodeoxynucleotides. [ABSTRACT FROM AUTHOR]

Asset market performance conditions the strategic context of cabinet terminations. In turn, information about cabinet terminations shapes how market actors evaluate the government's commitment to specific policies, affecting overall economic performance. To understand how the economy affects cabinet terminations, therefore, we must account for the endogeneity between cabinet outcomes and market performance. In this article, we model both cabinet terminations and speculative currency attacks. We argue that changes in the probability of different types of cabinet ends condition the probability that currency traders will sharply shift their assets out of a country. In turn, the probability of a speculative attack influences the probabilities of different types of cabinet ends—for instance, the higher the likelihood of speculative attack, the lower the chance of an early strategic election. We connect separate models of cabinet termination and speculative attacks using an instrumental-variables framework. [ABSTRACT FROM AUTHOR]

Working under the assumption that hormesis is triggered by specific types of DNA damage, this report focuses on the types of damage which form the signature of ionizing radiation. The key attribute of the signature is the clustering of damage, arising from clusters of energy deposition such that more than one site within a 10 base pair segment of DNA has been chemically altered. A brief overview is given on what is currently believed to be the primary components of clustered damage produced by the direct effect. The overview draws primarily on studies that utilize electron paramagnetic resonance to measure free radical intermediates and gel electrophoresis to measure clustered damage in plasmid DNA. Based on this information, the threshold for a radiation induced biological response is calculated. [ABSTRACT FROM AUTHOR]

The 17th Amendment established the direct election of senators. Although scholars have discounted the Amendment as inconsequential, we argue that it significantly changed patterns of election-seeking and legislative voting behavior. First, the Amendment negated the influence of state legislatures in senators’ decisions to stand for reelection, inducing more incumbents to run. Second, the Amendment introduced incentives for senators to moderate their public ideologies in pursuit of reelection. We employ a selection model to test the impact of the 17th Amendment on the interdependent decisions to stand for reelection and to shift late-term roll-call behavior. Using W-Nominate scores for major party senators serving from 1877 to 1932, we show that post-Amendment senators, particularly Republicans, were systematically more likely to moderate ideologically as elections approached. [ABSTRACT FROM AUTHOR]

We investigate the impact of parliamentary political processes on exchange rate volatility. During periods of potential political change, currency traders have less certainty about the future of government policy. Consequently, these periods will be associated with higher volatility—a measure of the predictability of exchange rate movements. We estimate a series of fractionally integrated exponential generalized autoregressive conditional heteroscedasticity models on four currencies using daily data: the British pound, the French franc, the Belgian franc, and the Swedish krona. The results indicate that, while political events often increased exchange rate volatility, participation in the European Monetary System helped stabilize the level of the exchange rate and reduce volatility. [ABSTRACT FROM AUTHOR]

Focuses on the foreign exchange market around the globe. Impact of technological innovations and market liberalization on market currency; Evaluation on the economic performance and political outcomes; Internationalization of economic activity influenced by democratic politics.

Comments on the variations in central bank independence in a political context. How cross-national differences in legislative government explain the variation of central bank institutions; Information on episodes of monetary reform; Influence of legislative-government relations in shaping the choice of central bank institutions.

We explore the consequences of involvement in scandal for members of Congress' (MCs) success within the House of Representatives. Our analyses target all MCs who served in the 101st to 112th Congresses (1989–2012). Across this time period, we identify 253 discrete member-term observations of professional or personal scandal. Our results demonstrate that scandal stalls the upward trajectory of MCs' careers in the chamber, affecting their levels of legislative effectiveness, their centrality to the congressional network, and their likelihood of gaining or losing prestigious committee assignments and leadership positions. Importantly, these effects can linger beyond the term following scandal, shaping MCs' behavior into the future. Our findings demonstrate that in addition to negative electoral repercussions, scandals can have important legislative consequences for members. [ABSTRACT FROM AUTHOR]

This study assesses how political parties' candidate selection strategies influence women's descriptive parliamentary representation. Focusing on proportional elections, it explores what determines whether parties place women in viable list positions. Evaluating party rankings at the individual level, it directly examines a mechanism – party nomination – central to prevailing explanations of empirical patterns in women's representation. Moreover, it jointly evaluates how incumbency and gender affect nomination. This study uses European Parliament elections to compare a plethora of parties, operating under numerous institutions, in the context of a single legislature. It finds that gender differences in candidate selection are largely explained by incumbency bias, although party ideology and female labor force participation help explain which parties prioritize the placement of novice women. [ABSTRACT FROM AUTHOR]

Parties in list systems must select candidates to best accomplish their electoral, organizational, and policy goals. In particular, parties must balance nominees’ policy-making potential against other aspects of candidate quality, such as electoral viability. We exploit the unique variation in candidates and parties in European elections to study this trade-off. We develop a statistical ranking model to examine how parties facing varying strategic contexts construct electoral lists and apply it to a novel data set chronicling the political backgrounds of candidates in the 2009 European parliamentary elections. Parties that place high salience on the target legislature, are well positioned to influence policy once in office, and have less access to competing policy-making venues place particular emphasis on institution-specific policy-making experience relative to other types of candidate experience. This systematic variation in parties’ candidate nomination strategies may fundamentally alter legislative output and partisan policy influence. [ABSTRACT FROM AUTHOR]

Presents an abstract of a study on violation of the 1949 Geneva Convention by Iraq's military personnel during the Persian Gulf War. Description of violations; Recommendations.

Studies in international political economy (IPE) that use survey-response data sets and survey (or field) experiments have grown dramatically in recent years. New developments in survey and experimental methodology have arguably influenced IPE scholars not only to think more deeply about the microfoundations of the preferences, attitudes, and political behavior of key IPE actors but also to use survey or experimental methods to test causal claims and predictions. Yet the reasons for the rapid growth in survey and experimental methods in IPE are more multifaceted. We therefore seek to answer the following three pertinent questions in the introduction. First, what are the main substantive puzzles and issue-areas that IPE scholars analyze via survey and experimental methods in their research? Second, what are the main methodological advantages and drawbacks from using survey and experimental methods in IPE? Third, what are the key substantive theoretical and empirical insights that scholars have learned from recent research in IPE that employs either survey or experimental methods (or both)? In addition to answering these questions here, we also provide a summary of each article included in the special issue. The introduction concludes with a road map for future studies on survey and experimental research in IPE. [ABSTRACT FROM AUTHOR]

It has long been assumed that the population of radicals trapped in irradiated DNA (that is, the radicals escaping recombination) would quantitatively account for the lesions observed in DNA. Recent results indicate that this is not the case. The yield of DNA lesions exceed the yield of trappable radicals. To account for a portion of this shortfall, it is thought that some of the initially formed 2′-deoxyribose radicals undergo a second oxidation by nearby base cation radicals to form 2′-carbocations. The carbocations react to give strand breaks and free base release. Schemes are presented to account for the major oxidation products observed including 8-oxoGua, 8-oxoAde, 5-OHMeUra, and free base release. Theoretical calculations were performed to ascertain the likelihood of the second oxidation step in these reaction pathways actually occurring, and to account for base sequence dependence and various levels of hydration. [ABSTRACT FROM AUTHOR]

Members of the European Parliament (MEPs) typically follow one of two career paths, either advancing within the European Parliament itself or returning to higher offices in their home states. We argue that these different ambitions condition legislative behavior. Specifically, MEPs seeking domestic careers defect from group leadership votes more frequently and oppose legislation that expands the purview of supranational institutions. We show how individual, domestic-party, and national-level variables shape the careers available to MEPs and, in turn, their voting choices. To test the argument, we analyze MEPs' roll-call voting behavior in the 5th session of the EP (1999-2004) using a random effects model that captures idiosyncrasies in voting behavior across both individual MEPs and specific roll-call votes. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) and online UVvisible absorption microspectrophotometry with X-ray crystallography have been used in a complementary manner to follow X-ray-induced disulfide-bond cleavage. Online UVvisible spectroscopy showed that upon X-irradiation, disulfide radicalization appeared to saturate at an absorbed dose of approximately 0.5-0.8 MGy, in contrast to the saturating dose of ~0.2 MGy observed using EPR at much lower dose rates. The observations suggest that a multi-track model involving product formation owing to the interaction of two separate tracks is a valid model for radiation damage in protein crystals. The saturation levels are remarkably consistent given the widely different experimental parameters and the range of total absorbed doses studied. The results indicate that even at the lowest doses used for structural investigations disulfide bonds are already radicalized. Multi-track considerations offer the first step in a comprehensive model of radiation damage that could potentially lead to a combined computational and experimental approach to identifying when damage is likely to be present, to quantitate it and to provide the ability to recover the native unperturbed structure. [ABSTRACT FROM AUTHOR]