Counterintuitive Role Research Articles

Phase-field modeling of two-dimensional crystal growth with anisotropic diffusion

In the present article, we introduce a phase-field model for thin-film growth with anisotropic step energy, attachment kinetics, and diffusion, with second-order (thin-interface) corrections. We are mainly interested in the limit in which kinetic anisotropy dominates, and hence we study how the expected shape of a crystallite, which in the long-time limit is the kinetic Wulff shape, is modified by anisotropic diffusion. We present results that prove that anisotropic diffusion plays an important, counterintuitive role in the evolving crystal shape, and we add second-order corrections to the model that provide a significant increase in accuracy for small supersaturations. We also study the effect of different crystal symmetries and discuss the influence of the deposition rate.

Epitaxial Graphene Growth and Shape Dynamics on Copper: Phase-Field Modeling and Experiments

The epitaxial growth of graphene on copper foils is a complex process, influenced by thermodynamic, kinetic, and growth parameters, often leading to diverse island shapes including dendrites, squares, stars, hexagons, butterflies, and lobes. Here, we introduce a phase-field model that provides a unified description of these diverse growth morphologies and compare the model results with new experiments. Our model explicitly accounts for the anisotropies in the energies of growing graphene edges, kinetics of attachment of carbon at the edges, and the crystallinity of the underlying copper substrate (through anisotropy in surface diffusion). We show that anisotropic diffusion has a very important, counterintuitive role in the determination of the shape of islands, and we present a "phase diagram" of growth shapes as a function of growth rate for different copper facets. Our results are shown to be in excellent agreement with growth shapes observed for high symmetry facets such as (111) and (001) as well as for high-index surfaces such as (221) and (310).

Impact of Atlantic SST and high frequency atmospheric variability on the 1993 and 2008 Midwest floods: Regional climate model simulations of extreme climate events

The role of sea surface temperature anomalies (SSTAs) in the Atlantic and eastern Pacific and high-frequency atmospheric variability from the Pacific during the 1993 and 2008 Midwest floods is investigated with a regional climate model. The SSTAs insignificantly modulate Midwest rainfall during the 1993 flood, but enhance precipitation during the 2008 peak flood by strengthening the southern portion of the Great Plains low-level jet, enhancing moisture transport from the Gulf of Mexico into the Midwest. This work suggests that while North Atlantic SST strongly controls Midwest decadal drought and pluvial periods, it plays a minimal or secondary role in modulating extreme flood events lasting weeks to months. A negative Pacific/North American (PNA) teleconnection marked the peak of both floods, suggesting a link between extreme Midwest warm season rainfall and high-frequency PNA variations. Simulations that apply a 10-day low-pass filter to the western lateral boundary condition indicate that interactions between the eddy and time-mean flow played a significant, but counterintuitive role, during the 1993 flood. Although above normal Pacific cyclone activity was observed to trigger heavy Midwest precipitation, the synoptic eddies also indirectly influenced rainfall by modifying the time-mean circulation. Simulations show that eddies from the Pacific dampened the positive rainfall anomalies by weakening vertically integrated moisture transport and upper level divergence anomalies over the Midwest.

The rocks don't lie: a geologist investigates Noah's flood

In Tibet, geologist David R. Montgomery heard a local story about a great flood that bore a striking similarity to Noah's Flood. Intrigued, Montgomery began investigating the world's flood stories and-drawing from historic works by theologians, natural philosophers, and scientists-discovered the counterintuitive role Noah's Flood played in the development of both geology and creationism. Steno, the grandfather of geology, even invoked the Flood in laying geology's founding principles based on his observations of northern Italian landscapes. Centuries later, the founders of modern creationism based their irrational view of a global flood on a perceptive critique of geology. With an explorer's eye and a refreshing approach to both faith and science, Montgomery takes readers on a journey across landscapes and cultures. In the process we discover the illusive nature of truth, whether viewed through the lens of science or religion, and how it changed through history and continues changing, even today.

How Knowledge Overlap Drives (and Doesn’t Drive) Developer Preferences for Joining Related Open Source Software Projects

Open Source Software communities are exemplars of online and virtual collaboration among software developers. However, such communities are typified by a scarcity of volunteers with the result that OSS projects typically strive to garner necessary expertise. This study attempts to understand how OSS projects can attract software developers to join its collective effort. We proceed by examining the role of a key construct, knowledge domain overlap, defined as the overlap between the expertise domain of a software project a developer is considering joining, and the combined expertise domains of her past software projects. While greater knowledge domain overlap should intuitively attract a developer to an OSS project this is not always so. Instead, we find that two contingencies -- community experience of a developer and the centrality of the OSS project in the community – play a counter-intuitive role in driving developer preferences for OSS projects. Our empirical analysis is based on the archival data of the joining behavior of 462 developers in 538 OSS projects. First, we find that developers prefer those projects more which have a higher knowledge domain overlap in both dimensions – technical and application domains. However, despite lower technical domain overlap projects are still able to attract developers who have greater community experience. Similarly, those projects which are centrally located in the community structure are also able to attract developers despite a lower technical domain overlap. In comparison, application domain overlap seems important across contexts. The findings have implications for knowledge-based innovation in open communities which are a hotbed of innovation.

No ‘home’ versus ‘away’ effects of decomposition found in a grassland–forest reciprocal litter transplant study

Plant litter often decomposes faster in the habitat from which it was derived (i.e. home) than when placed in foreign habitats (i.e. away), which has been called the home–field advantage (HFA) of litter decomposition. We tested whether the HFA of litter decomposition is driven by decomposer communities being specialized at decomposing litter in their home habitat, by reciprocally transplanting litter from grassland to early-successional forest. Unexpectedly, we found an overall disadvantage for at-home decomposition despite large differences in litter quality (lignin:N) between the two habitats. We found more evidence for habitat specialization among secondary decomposers (mites) than the primary decomposers (bacteria and fungi), suggesting that soil animals may be important in driving HFA patterns where they do exist. Grass litter decomposition in forest slowed down and became more fungal-based, while tree litter decomposition in grassland increased yet showed no shift to being bacterially-based, relative to ‘at home’ decomposition. This suggests a biological explanation for why a positive HFA was not observed. Our results highlight that both environmental context and soil biology can play an important and sometimes counter-intuitive role in modifying decomposition. A better understanding of the interaction between all three primary drivers of decomposition (the environment, litter quality and soil organisms) is necessary for reliable prediction of decomposition at global scales.

Intimate partner violence relationship dissolution among couples with children: the counterintuitive role of “Law and Order” neighborhoods

AbstractThis study examined the relationship between intimate partner violence (IPV) relationship dissolution and neighborhood concentrated disadvantage, ethnic heterogeneity, residential instability, collective efficacy, and legal cynicism. Data from the Project on Human Development in Chicago Neighborhoods (PHDCN) Longitudinal survey were used to identify 658 cases of IPV in Wave 1. A generalized boosting model (GBM) was used to determine the best proximal predictors of relationship dissolution from the longitudinal data. Controlling for these predictors, logistic regression of neighborhood characteristics from the PHDCN community survey was used to predict IPV relationship dissolution in Wave 2. Counterintuitively, the authors find that neighborhoods high in legal cynicism have a greater likelihood of IPV relationship dissolution, controlling for other variables in the logistic regression model. However, analyses did not find that IPV relationship dissolution was related to neighborhood concentrated disadvantage, ethnic heterogeneity, residential instability, and collective efficacy. © 2010 Wiley Periodicals, Inc.

Immunization with host-type CD8α+ dendritic cells reduces experimental acute GVHD in an IL-10–dependent manner

AbstractLittle is known about the role of active immunization in suppressing undesirable immune responses. Because CD8α+ dendritic cells (DCs) suppress certain immune responses, we tested the hypothesis that immunization of donors with host-derived CD8α+ DCs will reduce host-specific donor T-cell responses. BALB/c T cells from the animals that were immunized with B6 CD8α+ DCs demonstrated, in vitro and in vivo, significantly reduced proliferation and secretion of inflammatory cytokines but showed enhanced secretion of interleukin-10 (IL-10). The responses against third-party and model antigens were preserved demonstrating antigen specificity. The in vivo relevance was further demonstrated by the reduction on graft-versus-host disease (GVHD) in both a major histocompatibility complex–mismatched clinically relevant BALB/c → B6 model and major histocompatibility complex–matched, minor-mismatched C3H.SW → B6 model of GVHD. Immunization of the donors that were deficient in IL-10 (IL-10−/−) or with CD8α+ DCs from B6 class II (class II−/−) failed to reduce T-cell responses, demonstrating (1) a critical role for secretion of IL-10 by donor T cells and (2) a direct contact between the T cells and the CD8α+ DCs. Together, these data may represent a novel strategy for reducing GVHD and suggest a broad counterintuitive role for vaccination strategies in mitigating undesirable immune responses in an antigen-specific manner.

Disputing Limited Liability

This project presents six years of hand-collected federal district court data to analyze the first representative sample of veil piercing litigation. Our method identifies veil piercing complaints through Westlaw's trial pleadings database and codes each case through a detailed examination of PACER records. We test a variety of hypotheses to understand how such litigations are resolved. We find that plaintiffs succeed quite often in veil piercing litigation, if success is defined as winning on motions that do not terminate a case. A variety of legal and extra-legal factors predict such interstitial veil piercing successes. Voluntary creditor causes of action promote veil piercing; LLCs are in very limited circumstances better insulated from veil piercing claims than corporations; undercapitalization is strongly associated with success while conclusory grounds like facade and sham are not; and defendants' legal sophistication is predictive of plaintiff failure. Extra-legal factors play a more striking and counterintuitive role. Plaintiffs suing companies with few employees are much more likely to win veil piercing motions, and obtain relief in cases, than plaintiffs suing companies employing many workers. This results holds even when controlling for legally-relevant variables. Contrary to both theory and previous empirical work, we also find that judicial liberalism is inversely related to the likelihood of plaintiff success. Our results call into question existing normative and descriptive approaches to the disputation of limited liability and contribute to more general scholarship about selection effects and judicial behavior. They do not provide any easy answers to the question of what defendants can do to insulate themselves from veil piercing. Our analysis suggests: Very little, apart from being very big.

Collective Atomic Recoil Lasing with a Partially Coherent Pump

We investigate the effect of pump phase noise on the collective backscattering of light by a cold, collisionless atomic gas. We show that for a partially coherent pump field, the growth rate of the backscattered field is reduced relative to that for a coherent pump, but the backscattered intensity can be increased. Our results demonstrate that fluctuations and noise can play a counterintuitive role in nonlocally coupled many-body systems.

Adoption of Environmental Management Systems by Farmers: An Empirical Application to ISO 14001

This article undertakes an empirical investigation of the determinants of voluntary adoption of the ISO 14001 environmental management system by French farmers. The adoption model incorporates the expected profitability of implementing the standard and investigates the impact of prior knowledge on the probability of adopting. Two information measures are considered: a “reported information” indicator and an “estimated knowledge” score. The probit parameter estimates reveal that, while the expected profitability of implementing the standard is a significant determinant of adoption, real and perceived prior knowledge measures play a significant but potentially counterintuitive role.