Structural Explanations Research Articles

THE RACIAL ECOLOGY OF LEAD POISONING

AbstractThis paper examines the racial ecology of lead exposure as a form of environmental inequity, one with both historical and contemporary significance. Drawing on comprehensive data from over one million blood tests administered to Chicago children from 1995-2013 and matched to over 2300 geographic block groups, we address two major questions: (1) What is the nature of the relationship between neighborhood-level racial composition and variability in children’s elevated lead prevalence levels? And (2) what is the nature of the relationship between neighborhood-level racial composition and rates of change in children’s prevalence levels over time within neighborhoods? We further assess an array of structural explanations for observed racial disparities, including socioeconomic status, type and age of housing, proximity to freeways and smelting plants, and systematic observations of housing decay and neighborhood disorder. Overall, our theoretical framework posits lead toxicity as a major environmental pathway through which racial segregation has contributed to the legacy of Black disadvantage in the United States. Our findings support this hypothesis and show alarming racial disparities in toxic exposure, even after accounting for possible structural explanations. At the same time, however, our longitudinal results show the power of public health policies to reduce racial inequities.

Non-Abelian family symmetries as portals to dark matter

Non-Abelian family symmetries offer a very promising explanation for the flavour structure in the Standard Model and its extensions. We explore the possibility that dark matter consists in fermions that transform under a family symmetry, such that the visible and dark sector are linked by the familons - Standard Model gauge singlet scalars, responsible for spontaneously breaking the family symmetry. We study three representative models with non-Abelian family symmetries that have been shown capable to explain the masses and mixing of the Standard Model fermions. One of our central results is the possibility to have dark matter fermions and at least one familon with masses on and even below the experimentally accessible TeV scale. In particular we discuss the characteristic signatures in collider experiments from light familon Fields with a non-Abelian family symmetry, and we show that run I of the LHC is already testing this class of models.

God, nature and language: An essay on Berkeley's philosophy of science

This paper gives a critical account of the precise character of Berkeley's fictionalism and instrumentalism in his philosophy of science. Two replies are given to the objections typically raised against his vision of science and its incompatibility with the scientific practice. The first objection claims that his immaterialism is incompatible with the natural causation, and the second that it is not able to give an explanation for the complex structure of issues raised by natural sciences. The replies rely on Berkeley's thesis concerning the language of God, claiming that there are no causal but only semantic relations between the signs and the signified in the world. The system of nature constitutes a language which God uses to communicate with the finite creatures.

Transparency: An Organizational Ideal and its Limited Applicability (WITHDRAWN)

Transparency often fails to yield those positive effects placed upon it by advocates. Common answers refer to micro or macro structural explanations and generally take a reformist approach: The mes...

Developing critical consciousness or justifying the system? A qualitative analysis of attributions for poverty and wealth among low-income racial/ethnic minority and immigrant women.

Economic inequality is a growing concern in the United States and globally. The current study uses qualitative techniques to (a) explore the attributions low-income racial/ethnic minority and immigrant women make for poverty and wealth in the U.S., and (b) clarify important links between attributions, critical consciousness development, and system justification theory. In-depth interview transcripts from 19 low-income immigrant Dominican and Mexican and native African American mothers in a large Northeastern city were analyzed using open coding techniques. Interview topics included perceptions of current economic inequality and mobility and experiences of daily economic hardships. Almost all respondents attributed economic inequality to individual factors (character flaws, lack of hard work). Structural explanations for poverty and wealth were expressed by fewer than half the sample and almost always paired with individual explanations. Moreover, individual attributions included system-justifying beliefs such as the belief in meritocracy and equality of opportunity and structural attributions represented varying levels of critical consciousness. Our analysis sheds new light on how and why individuals simultaneously hold individual and structural attributions and highlights key links between system justification and critical consciousness. It shows that critical consciousness and system justification do not represent opposite stances along a single underlying continuum, but are distinct belief systems and motivations. It also suggests that the motive to justify the system is a key psychological process impeding the development of critical consciousness. Implications for scholarship and intervention are discussed.

Bananas, pesticides and health in southwestern Ecuador: A scalar narrative approach to targeting public health responses

Public health responses to agricultural pesticide exposure are often informed by ethnographic or other qualitative studies of pesticide risk perception. In addition to highlighting the importance of structural determinants of exposure, such studies can identify the specific scales at which pesticide-exposed individuals locate responsibility for their health issues, with implications for study and intervention design. In this study, an ethnographic approach was employed to map scalar features within explanatory narratives of pesticides and health in Ecuador's banana-producing El Oro province. Unstructured observation, 14 key informant interviews and 15 in-depth semi-structured interviews were carried out during 8 months of fieldwork in 2011–2013. Analysis of interview data was informed by human geographic literature on the social construction of scale. Individual-focused narratives of some participants highlighted characteristics such as carelessness and ignorance, leading to suggestions for educational interventions. More structural explanations invoked farm-scale processes, such as uncontrolled aerial fumigations on plantations owned by elites. Organization into cooperatives helped to protect small-scale farmers from ‘deadly’ banana markets, which in turn were linked to the Ecuadorian nation-state and actors in the banana-consuming world. These scalar elements interacted in complex ways that appear linked to social class, as more well-off individuals frequently attributed the health problems of other (poorer) people to individual behaviours, while providing more structural explanations of their own difficulties. Such individualizing narratives may help to stabilize inequitable social structures. Research implications of this study include the possibility of using scale-focused qualitative research to generate theory and candidate levels for multi-level models. Equity implications include a need for public health researchers planning interventions to engage with scale-linked inequities, such as disparities within nation-states. Finally, the prominence of the global North in explanatory narratives is a useful reminder that ‘structural factors’ prominently include inequities related to the legacies of colonialism.

Zones of rebellion: Kurdish insurgents and the Turkish state

Earlier research on civil war has sought to reveal its fundamental causes and understand why ordinary people would resort to political violence. This line of research has offered great theoretical insights into the structural mechanisms that caused civil wars, particularly embodying grievance-based approaches (be they political, economic, or social). Yet these structural explanations have remained limited in demonstrating the timing of civil war breakouts at certain periods but not others and the persistence of civil wars over longer periods. In that regard, Zones of Rebellion seeks to bring a nuanced understanding of the emergence and persistence of civil wars by giving agency to the combatants along with their organizational and ideological choices through a detailed case study of the KurdistanWorkers’ Party (Partiya Karkeren Kurdistane, PKK) and the counterinsurgency efforts of the Turkish state. In doing so, the book offers process-oriented explanations within which violence transforms identities on the one hand and historically informed organizational choices of the combatants cause the conflict persist in the long run on the other hand. Rather than seeing the Kurdish conflict of Turkey as a function of preconflict ethnic grievances, this study shows that “civil wars can be viewed as incomplete groupmaking projects” (130). While the first part of the book analyzes the organization, ideology, and strategy of the PKK, the second part observes the counterinsurgency of the Turkish state along with its organization, ideology, and strategy between 1984 and 2008. The book has two main arguments. First, the combatants (i.e., the Turkish state and the Kurdish insurgency) are resourcedependent organizations. By resource, the authors refer to the crucial significance of territory and people. Depending on the degrees of civilian support and territorial control of the combatants, distinct zones of violence have gradually emerged dur-

Three worlds of health technology assessment: explaining patterns of diffusion of HTA agencies in Europe.

In the past two decades, setting up independent health technology assessment (HTA) agencies has become a popular tool to inform reimbursement decision-making in health care, spreading from Northern European countries across Western Europe but much less so to post-communist countries. Structural political science explanations leave gaps in clarifying this diffusion pattern. This paper proposes a theoretical model focusing on the influence of domestic epistemic communities mitigating policy diffusion. Based on a review of HTA institutions in the EU, it proposes a chronological taxonomy of HTA agencies in Europe (the forerunners, the mainstreamers and the non-adopters) and asks why there is such an important East-West divide. The paper discusses theoretical explanations from different literatures, finding unsatisfactory many traditional political science answers such as the degree of centralization of a country's health system, its financial organization (Bismarckian or Beveridgian), the attitude toward independent regulatory bodies in general, the influence of international actors, or lack of resources. Finally, it suggests cases for empirical testing of the domestic epistemic communities model.

Effect of UV-irradiation on spectral properties of squaraine dye in diluted solutions

The photosensitive symmetric derivative of quadratic acid (DMSAQ) was been synthesized for the biomedical or analytical purposes. The photochemical properties of the obtained dye were studied by means of absorption spectroscopy in six solvents of different polarity and photoreactivity: chloroform (CHCl3), tetrahydrofuran (THF), ethanol (EtOH), acetonitrile (ACN) dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). Both high-energy radiation (UV–vis) and radiation with lower energy from visible range were applied. It was found that the fastest squaraine dye bleaching takes place in CHCl3 and DMF solutions, which is caused by photosensitivity of these solvents. The most spectacular stabilization effect has been found in DMSO under both visible and ultraviolet radiation. It was shown that the course of photochemical reactions of squaraine in solutions depends on the solvent properties, energy of radiation and mutual solute-solvent interactions. The explanation of squaraine structure and molecular interactions and their impact on photochemistry of studied systems has been supported by theoretical calculations.

Crisis in an Atlantic Empire: Spain and New Spain, 1808–1810, by Barbara H. Stein & Stanley J. Stein

Crisis in an Atlantic Empire: Spain and New Spain, 1808-1810, by Barbara H. Stein & Stanley J. Stein. Baltimore, Johns Hopkins University Press, 2014. viii, 795 pp. $89.95 US (cloth). For over a half-century, the duo of Barbara and Stanley Stein has been labouring on a massive history of the evolution of the Spanish empire, especially the complex interdependence between Spain and Mexico. This book is the last installment, the fourth volume of what must surely count as one of the great epics of the making of the modem world by Bourbons, their backers, and the swelling ranks of rivals and critics. This particular volume is a study of the feverish years between Napoleon's invasion of Spain to the outbreak of the plebeian revolt in Mexico led by the provincial priest, Father Miguel Hidalgo y Costilla. After a century of struggles to reform and adapt to the internal and external pressures of an earlier globalization, the old empire finally entered the phase of its collapse. Recent scholarship of the Spanish empire has turned increasingly to the study of Atlantic cultural and religious exchanges. The earlier structuralist explanations of the Iberian empires--that emphasized the durable power of the alliance between monopoly merchants and ancien regime ministers --went by the wayside to be replaced by a different portrait of power. Drained of class interests, the new historiography accents the cultural dimensions of authority. At first blush, this book appears to be a throwback. The underlying theme of the book--indeed the series--is that an empire ruled by a patrimonial monarch and backed by merchant-rentiers who thrived off protection of their privileges, forced sales to Indians, and a gamut of coerced labour could not possibly be serious about Enlightened reform. There was something intrinsically reactive, not to say reactionary, about the Spanish ancien regime. Why it did not collapse was because of the wealth extracted from the Americas, especially Mexico. In fact, the Steins present a subtle account of a trans-Atlantic elite adapting to pressures and incentives, but only up to the limits of their self-interests and convictions. The strong impression one gets in this book is of an imperial ruling class--with some remarkable detail about the interlaced connections between private and public pursuits--with a powerful, pragmatic, elan. This class knew that at the bottom of the social pyramid lay landless peasants of Andalusia, growing Cuban slave populations, and 5 million mestizos, mulattoes, and ethnic Indians exploited by dominant whites, criollo and pensinsular(p. 174). In this context, reform was a dangerous game and this book pulls the veil back on the memoranda and calculus of elites grappling with just how much they had to concede before letting events get out of control. Indeed, it provides a richly detailed account of behind the scenes debates about policymaking, one that demolishes misguided depictions of the Spanish regime as absolutist or blind to the threats that closed like a noose around it. But it was not up to monarchs and ministers to dictate the whens and whys of imperial adaptation. While there was much internal dispute over whether to give in to the neutral trade demands of some colonial ports, or whether to adjust the averia tax administered by merchant guilds on behalf of the crown, it was ultimately the pressure from Paris that forced the hand of rulers. …

Chronic Instability and the Limits of Path Dependence

Historical institutionalism challenged older forms of comparative historical analysis by moving away from purely structural explanations of historical outcomes. Instead it posited that there were critical junctures in which actors chose between institutional alternatives, which in turn led to path dependence. I examine a phenomenon neglected both by historical institutionalism and older forms of historical analysis—chronic instability. Instead of institutional lock-in, some junctures lead to periods of instability in which a series of regimes replace each other in rapid succession. Three different causal mechanisms that routinely contribute to chronic instability—external shocks, changing configurations of actors, and disjuncture between the logic of change and mechanisms of reproduction—are explored in depth. The plausibility of the theory is illustrated by an examination of regime instability in Germany from the collapse of the Empire in 1918 through the founding of the Federal Republic in 1949.

Diplomacy after Policymaking: Theorizing Hyper-Empowered Individuals

Diplomatic Afterlives. Edited by Andrew F Cooper. Malden, MA: Polity Press, 2015. 206 pp., $24.95 paperback (ISBN-13: 978-0-7456-6199-5). The academic study of diplomacy in the discipline of International Relations (IR) has flourished in recent years (see Sending, Pouliot, and Neumann ⇓; Pouliot and Cornut ⇓ for recent volumes that include substantive reviews of the recent diplomacy renaissance). After decades of discounting diplomacy's importance in favor of structural explanations (Rathbun ⇓:1), diplomacy has (re)-emerged on the landscape of mainstream IR theorizing. One reason for this is the growing recognition that states spend so much time engaging in diplomacy, it must be for a good reason (if we assume that states take purposeful actions). More important is the growing sense that structural features beyond the control of individuals, such as power, do not account for the tremendous variation we see in political outcomes in the international system. In order to make sense of this variation, we need a theory of agency, an understanding of how individual agents can affect outcomes independent of other structural factors. Several works in the last few years have attempted to construct theories of diplomacy as theories of agency. Rathbun's (⇓) Diplomacy's Value: Creating Security in 1920s Europe and the Contemporary Middle East is an exemplar. Rathbun sets out discrete propositions about how diplomatic styles and diplomat characteristics, particularly prosocial vs. proself orientations, combine to help explain the Locarno period in Europe. Yarhi-Milo's (⇓) Knowing the Adversary: Leaders, Intelligence, and Assessment of Intentions in International Relations demonstrates that policymakers often make decisions about the intentions of states not just by looking at structural factors, but instead by relying on preexisting beliefs and …

Settlement-Size Scaling among Prehistoric Hunter-Gatherer Settlement Systems in the New World.

Settlement size predicts extreme variation in the rates and magnitudes of many social and ecological processes in human societies. Yet, the factors that drive human settlement-size variation remain poorly understood. Size variation among economically integrated settlements tends to be heavy tailed such that the smallest settlements are extremely common and the largest settlements extremely large and rare. The upper tail of this size distribution is often formalized mathematically as a power-law function. Explanations for this scaling structure in human settlement systems tend to emphasize complex socioeconomic processes including agriculture, manufacturing, and warfare—behaviors that tend to differentially nucleate and disperse populations hierarchically among settlements. But, the degree to which heavy-tailed settlement-size variation requires such complex behaviors remains unclear. By examining the settlement patterns of eight prehistoric New World hunter-gatherer settlement systems spanning three distinct environmental contexts, this analysis explores the degree to which heavy-tailed settlement-size scaling depends on the aforementioned socioeconomic complexities. Surprisingly, the analysis finds that power-law models offer plausible and parsimonious statistical descriptions of prehistoric hunter-gatherer settlement-size variation. This finding reveals that incipient forms of hierarchical settlement structure may have preceded socioeconomic complexity in human societies and points to a need for additional research to explicate how mobile foragers came to exhibit settlement patterns that are more commonly associated with hierarchical organization. We propose that hunter-gatherer mobility with preferential attachment to previously occupied locations may account for the observed structure in site-size variation.

El principio de razón suficiente

The Principle of Sufficient Reason According to Alexander R. Pruss the Principle of Sufficient Reason (PSR) is essential to solve two classical problems of philosophy: 1) the problem of infinite regress and 2) the non-emergence of entities ex nihilo. Furthermore, the use of the PSR would correspond to an Aristotelian-Thomistic explanation of the metaphysical structure of individuals. However, the argument developed by Pruss has some defects that ultimately lead to the conclusion that the PSR is superfluous.

On the transient dynamics of the wake and trajectory of free falling cones with various apex angles

The early free fall stages of cones with a density ratio 1.18 and apex angles of $$30^{\circ }$$ , $$45^{\circ }$$ , $$60^{\circ }$$ , and $$90^{\circ }$$ were studied using a wireless 3-axis gyroscope and accelerometer to describe the cone 3D motions, while particle image velocimetry was used to capture the induced flow in the near wake. The Reynolds number based on the cones diameter and the velocity at which the cone reaches the first local velocity maximum is found to consistently set the limit between two distinctive states. Relatively rapid growth in the cone nutation and departure from the vertical axis is observed after this Re is reached. Sequences of vertical velocity, swirling strength, LES-decomposed velocity, and pressure fields show the formation and growth of a large and initially symmetric recirculation bubble at the cone base. Those also highlight the presence of a symmetric 3D vortex rollup dominating the near wake in the early stages of the fall. A shear layer develops at the edge of the wake and manifests in the periodic shedding of Kelvin–Helmholtz vortices that, due to the nature of the recirculation bubble, reorganize to constitute a part of the rollup. Later in the fall, the wake loses symmetry and shows high population of vortical structures leading to turbulence. The asymmetric wake leads to strong interactions between the flow field and the cone evidenced by the shedding of a part of the 3D large-scale vortex rollup. This shedding process along with the cone rotation around its own axis provides a possible explanation of the helical wake structure observed in other studies.

A structural approach to politicisation in the Euro crisis

Domestic opportunity structures and political actors’ positions are widely regarded as the most important explanatory factors for EU politicisation. The euro crisis, however, has revealed cleavages across rather than within countries, suggesting structural factors as a potential explanation for politicisation. Based on the political economy literature on Europe’s Economic and Monetary Union, this contribution develops a structural approach to politicisation with respect to countries’ power and variety of capitalism. Using a content and claims analysis of business papers in Germany, France, Austria and Ireland before and during the crisis, the findings reveal a differentiated pattern of politicisation. While an expansion of actors indicates that EMU became more politicised during the crisis, polarisation remained low within countries. Countries’ variety of capitalism and their perceived power in the EU largely explain the substance and objects of politicisation. The findings encourage further research considering structural explanations for differentiated politicisation in less elite-centred settings of politicisation.

Elliptical Small‐Angle X‐Ray Scattering Patterns from Aligned Lamellar Arrays

ABSTRACTSemicrystalline polymers aligned by drawing into films or fibers produce small‐angle X‐ray scattering patterns with two or four spots. Some liquid crystalline materials, cybotactic nematics, produce extremely similar patterns when oriented in magnetic fields. A structure of stacked lamellae, tilted for four point patterns, explain the basic features. However, the peak intensity positions of the broadened reflections lie not on a layer line or on the arc of a circle, but very close to an ellipse. Specific structural explanations of this feature have been suggested, but models using an equilibrium distribution of molecular orientations and lamellar tilts can predict elliptical shapes for the reflections. The model parameters are chosen by fitting the entire 2D intensity distribution of the scattering pattern. Assumptions required for modeling make some fitted parameters uncertain, but it is clear that the elliptical form can emerge from a statistical distribution of the properties of the stacks of lamellae, without a directly assignable structural cause. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 308–318

Atomic and electronic structures of Si(1 1 1)--Au and (6 × 6)-Au surfaces

Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the -Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the -Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the -Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the -Au phase. Extra Au atoms bound in interstitial sites of the -Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a -Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the -Au structure. The -Au phase is 2D chiral and this is evident in computed and actual STM images. -Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si–Au top layers of the -Au and -Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given.

Progesterone 5β-reductases/iridoid synthases (PRISE): gatekeeper role of highly conserved phenylalanines in substrate preference and trapping is supported by molecular dynamics simulations

Vein Patterning 1 (VEP1)-encoded progesterone 5β-reductases/iridoid synthases (PRISE) belong to the short-chain dehydrogenase/reductase superfamily of proteins. They are characterized by a set of highly conserved amino acids in the substrate-binding pocket. All PRISEs are capable of reducing the activated C=C double bond of various enones enantioselectively and therefore have a potential as biocatalysts in bioorganic synthesis. Here, recombinant forms of PRISEs of Arabidopsis thaliana and Digitalis lanata were modified using site-directed mutagenesis (SDM). In rDlP5βR, a set of highly conserved amino acids in the vicinity of the catalytic center was individually substituted for alanine resulting in considerable to complete loss of enone reductase activity. F153 and F343, which can be found in most PRISEs known, are located at the outer rim of the catalytic cavity and seem to be involved in substrate binding and their role was addressed in a series of SDM experiments. The wild-type PRISE accepted progesterone (large hydrophobic 1,4-enone) as well as 2-cyclohexen-1-one (small hydrophilic 1,4-enone), whereas the double mutant rAtP5βR_F153A_F343A converted progesterone much better than the wild-type enzyme but almost lost its capability of reducing 2-cyclohexen-1-one. Recombinant Draba aizoides P5βR (rDaP5βR) has a second pair of phenylalanines at position 156 and 345 at the rim of the binding site. These two phenylalanines were introduced into rAtP5βR_F153A_F343A and the resulting quadruple mutant rAtP5βR_F153A_F343A_V156F_V345F partly recovered the ability to reduce 2-cyclohexen-1-one. These results can best be explained by assuming a trapping mechanism in which phenylalanines at the rim of the substrate-binding pocket are involved. The dynamic behavior of individual P5βRs and mutants thereof was investigated by molecular dynamics simulations and all calculations supported the ‘gatekeeper’ role of phenylalanines at the periphery of the substrate-binding pocket. Our findings provide structural and mechanistic explanations for the different substrate preferences seen among the natural PRISEs and help to explain the large differences in catalytic efficiency found for different types of 1,4-enones.

THE RADIO PROPERTIES OF RADIO-LOUD NARROW-LINE SEYFERT 1 GALAXIES ON PARSEC SCALES

We present the detection of compact radio structures of fourteen radio-loud narrow line Seyfert 1 (NLS1) galaxies from Very Long Baseline Array observations at 5 GHz, which were performed in 2013. While 50\% of the sources of our sample show a compact core only, the remaining 50\% exhibit a core-jet structure. The measured brightness temperatures of the cores range from $10^{8.4}$ to $10^{11.4}$ K with a median value of $10^{10.1}$ K, indicating that the radio emission is from non-thermal jets, and that, likely, most sources are not strongly beamed, then implying a lower jet speed in these radio-loud NLS1 galaxies. In combination with archival data taken at multiple frequencies, we find that seven sources show flat or even inverted radio spectra, while steep spectra are revealed in the remaining seven objects. Although all these sources are very radio-loud with $R > 100$, their jet properties are diverse, in terms of their milli-arcsecond (mas) scale (pc scale) morphology and their overall radio spectral shape. The evidence for slow jet speeds (i.e., less relativistic jets), in combination with the low kinetic/radio power, may offer an explanation for the compact VLBA radio structure in most sources. The mildly relativistic jets in these high accretion rate systems are consistent with a scenario, where jets are accelerated from the hot corona above the disk by the magnetic field and the radiation force of the accretion disk. Alternatively, a low jet bulk velocity can be explained by low spin in the Blandford-Znajek mechanism.