bluuebunny/crossref_metadata_2025 huggingface dataset:
A Theory of Baroclinic Turbulence
Authors: Farrell Brian F. , Ioannou Petros J.
Published: February 2009

Understanding the physical mechanism maintaining fluid turbulence remains a fundamental theoretical problem. The two-layer model is an analytically and computationally simple system in which the dynamics of turbulence can be conveniently studied; in this work, a maximally simplified model of the statistically steady turbulent state in this system is constructed to isolate and identify the essential mechanism of turbulence. In this minimally complex turbulence model the effects of nonlinearity are parameterized using an energetically consistent stochastic process that is white in both space and time, turbulent fluxes are obtained using a stochastic turbulence model (STM), and statistically steady turbulent states are identified using stochastic structural stability theory (SSST). These turbulent states are the fixed-point equilibria of the nonlinear SSST system. For parameter values typical of the midlatitude atmosphere, these equilibria predict the emergence of marginally stable eddy-driven baroclinic jets. The eddy variances and fluxes associated with these jets and the power-law scaling of eddy variances and fluxes are consistent with observations and simulations of baroclinic turbulence. This optimally simple model isolates the essential physics of baroclinic turbulence: maintenance of variance by transient perturbation growth, replenishment of the transiently growing subspace by nonlinear energetically conservative eddy–eddy scattering, and equilibration to a statistically steady state of marginal stability by a combination of nonlinear eddy-induced mean jet modification and eddy dissipation. These statistical equilibrium states provide a theory for the general circulation of baroclinically turbulent planetary atmospheres.
Evidence for Submesoscale Barriers to Horizontal Mixing in the Ocean from Current Measurements and Aerial Photographs
Authors: Gildor Hezi , Fredj Erick , Steinbuck Jonah , Monismith Stephen
Published: February 2009

Ocean submesoscale (∼2–20 km) mixing processes play a major role in ocean dynamics, in physical–biological interactions (e.g., in the dispersion of larvae), and in the dispersion of pollutants. In this paper, horizontal mixing on a scale of a few kilometers is investigated, from observations of surface currents, using highly resolved (300 m) high-frequency radar. These results show the complexity of ocean mixing on scales of a few kilometers and the existence of temporary barriers to mixing that can affect the dispersion of biological materials and pollutants. These barriers are narrow [O(100 m)] and can survive for a few days. The existence of these barriers is supported in simultaneous aerial photographs. The barriers observed here may require a new approach to the way horizontal mixing is parameterized in ocean and climate models.
An Ocean Circulation Model Based on Operator-Splitting, Hamiltonian Brackets, and the Inclusion of Sound Waves
Authors: Salmon Rick
Published: February 2009

This paper offers a simple, entirely prognostic, ocean circulation model based on the separation of the complete dynamics, including sound waves, into elementary Poisson brackets. For example, one bracket corresponds to the propagation of sound waves in a single direction. Other brackets correspond to the rotation of the velocity vector by individual components of the vorticity and to the action of buoyancy force. The dynamics is solved by Strang splitting of the brackets. Key features of the method are the assumption that the sound waves propagate exactly one grid distance in a time step and the use of Riemann invariants to solve the sound-wave dynamics exactly. In these features the method resembles the lattice Boltzmann method, but the flexibility of more conventional methods is retained. As in the lattice Boltzmann method, very short time steps are required to prevent unrealistically strong coupling between the sound waves and the slow hydrodynamic motions of primary interest. However, the disadvantage of small time steps is more than compensated by the model’s extreme simplicity, even in the presence of very complicated boundaries, and by its massively parallel form. Numerical tests and examples illustrate the practicality of the method.
Eddy Formation and Shedding in a Separating Boundary Current
Authors: Pichevin Thierry , Herbette Steven , Floc’h France
Published: February 2009

This study deals with the separation of western boundary currents within a reduced-gravity framework, and it analyzes the formation of eddies in the separation region and the conditions of their shedding into the open ocean. It shows that the separation point of the current oscillates along the coast so that the retroflected eastward current develops meanders. These meanders grow, drift westward under the influence of β, and finally hit the coastal current, which leads to the periodic formation of eddies. This study also highlights the impact by the geometrical configurations of the flow and coastline upon the existence or lack of a subsequent shedding of these eddies: a shedding occurs when no obstacle hinders the β-induced westward drift of the eddies. This happens when either (i) the current retroflects far enough beyond the tip of the coast so that, because of β, the eddies can propagate westward without being blocked, or (ii) the tilt of the coast is small enough so that the alongshore component of the β-induced velocity is enhanced and the eddies can escape from the retroflection region.
Hepatic Indicators of Oxidative Stress and Tissue Damage Accompanied by Systemic Inflammation in Rats Following a 24‐Hour Infusion of an Unstable Lipid Emulsion Admixture
Authors: Driscoll David F. , Ling Pei‐Ra , Andersson Charlotte , Bistrian Bruce R.
Published: February 2009

Background: Use of lipid emulsions in parenteral nutrition therapy is an important source of daily energy in substitution of potentially harmful glucose calories when given in excess in the intensive care unit. When added to parenteral nutrition (PN) admixtures as a total nutrient admixture (TNA), the stability and safety of the emulsion may be compromised. Development of a rat model of a stable vs unstable lipid infusion would enable a study of the potential risk. Design: Prospective, randomized, controlled study. Methods: Surgical placement of a jugular venous catheter for the administration of TNAs was performed. Two groups were studied: a stable or s‐TNA (n = 16) and an unstable or u‐TNA (n = 17) as a 24‐hour continuous infusion. Stability of TNAs was determined immediately before and after infusion using a laser‐based method approved by the United States Pharmacopeia. Results: Blood levels of aspartate aminotransferase, glutathione‐S‐transferase, and C‐reactive protein were significantly elevated in u‐TNA vs s‐TNA (P < .05). Also, liver tissue concentrations of malondialdehyde were significantly higher in the u‐TNA group (P < .05), and triglyceride tissue levels were also higher in u‐TNA and approached statistical significance (P = .077). Conclusions: Unstable lipid infusions over 24 hours produce evidence of hepatic accumulation of fat associated with oxidative stress, liver injury, and a low‐level systemic inflammatory response.
Pharmacology of GLP-1-based therapies
Authors: Holst Jens Juul
Published: February 2009

Glucagon-like peptide-1 GLP-1 is a naturally occurring 30-amino acid peptide synthesised in intestinal endocrine L cells. GLP-1 mediates glucose homeostasis through stimulation of glucose-dependent insulin secretion, biosynthesis of insulin and inhibition of glucagon secretion. These effects have potential clinical value in type 2 diabetes. However, because native GLP-1 is rapidly degraded to its inactive form by dipeptidyl peptidase-4 (DPP-4), it has a short half-life in vivo . Strategies to overcome this therapeutic limitation include developing GLP-1 mimetics and analogues with longer half-lives and to inhibit DPP-4. Exenatide (exendin-4) is a 39-amino acid peptide originally derived from the venom of the Gila monster lizard, and shares a 53% sequence identity with human GLP-1. Exenatide has a longer circulating half-life, reflecting relative resistance to DPP-4 degradation, and is administered twice daily. Liraglutide is a once-daily human GLP-1 analogue with high (97%) sequence identity. The specific structural modifications that characterise liraglutide result in increased self-association (allowing slow absorption from the subcutaneous depot), promote albumin binding and reduce susceptibility to DPP-4, giving liraglutide a half-life of 13 hours after once-daily administration. Preliminary studies of exenatide and liraglutide show clinically relevant reductions in glycosylated haemoglobin A1c (HbA1c) compared with placebo, without hypoglycaemia and with weight loss of up to 3 kg. DPP-4 inhibitors, such as vildagliptin (not available in the USA) and sitagliptin can help stabilise postprandial GLP-1 levels and thus produce desirable effects on insulin and glucagon production. The potential for weight reduction with DPP-4 inhibitors appears limited, perhaps reflecting the limited increase in GLP-1 levels achieved with these agents.Br J Diabetes Vasc Dis, 2008;8 (Suppl 2) : S10—S18
Differentiation therapy of leukemia: 3 decades of development
Authors: Nowak Daniel , Stewart Daphne , Koeffler H. Phillip
Published: February 2009

A characteristic feature of leukemia cells is a blockade of differentiation at a distinct stage in cellular maturation. In the 1970s and 1980s, studies demonstrating the capabilities of certain chemicals to induce differentiation of hematopoietic cell lines fostered the concept of treating leukemia by forcing malignant cells to undergo terminal differentiation instead of killing them through cytotoxicity. The first promising reports on this notion prompted a review article on this subject by us 25 years ago. In this review, we revisit this interesting field of study and report the progress achieved in the course of nearly 3 decades. The best proof of principle for differentiation therapy has been the treatment of acute promyelocytic leukemia with all-trans retinoic acid. Attempts to emulate this success with other nuclear hormone ligands such as vitamin D compounds and PPARγ agonists or different classes of substances such as hematopoietic cytokines or compounds affecting the epigenetic landscape have not been successful on a broad scale. However, a multitude of studies demonstrating partial progress and improvements and, finally, the new powerful possibilities of forward and reverse engineering of differentiation pathways by manipulation of transcription factors support the continued enthusiasm for differentiation therapy of leukemia in the future.
Short-term genome evolution of Listeria monocytogenes in a non-controlled environment
Authors: Orsi Renato H , Borowsky Mark L , Lauer Peter , Young Sarah K , Nusbaum Chad , Galagan James E , Birren Bruce W , Ivy Reid A , Sun Qi , Graves Lewis M , Swaminathan Bala , Wiedmann Martin
Published: February 2009

Background

While increasing data on bacterial evolution in controlled environments are available, our understanding of bacterial genome evolution in natural environments is limited. We thus performed full genome analyses on fourListeria monocytogenes, including human and food isolates from both a 1988 case of sporadic listeriosis and a 2000 listeriosis outbreak, which had been linked to contaminated food from a single processing facility. All four isolates had been shown to have identical subtypes, suggesting that a specificL. monocytogenesstrain persisted in this processing plant over at least 12 years. While a genome sequence for the 1988 food isolate has been reported, we sequenced the genomes of the 1988 human isolate as well as a human and a food isolate from the 2000 outbreak to allow for comparative genome analyses.

Results

The twoL. monocytogenesisolates from 1988 and the two isolates from 2000 had highly similar genome backbone sequences with very few single nucleotide (nt) polymorphisms (1 – 8 SNPs/isolate; confirmed by re-sequencing). While no genome rearrangements were identified in the backbone genome of the four isolates, a 42 kb prophage inserted in the chromosomalcomKgene showed evidence for major genome rearrangements. The human-food isolate pair from each 1988 and 2000 had identical prophage sequence; however, there were significant differences in the prophage sequences between the 1988 and 2000 isolates. Diversification of this prophage appears to have been caused by multiple homologous recombination events or possibly prophage replacement. In addition, only the 2000 human isolate contained a plasmid, suggesting plasmid loss or acquisition events. Surprisingly, besides the polymorphisms found in thecomKprophage, a single SNP in the tRNA Thr-4 prophage represents the only SNP that differentiates the 1988 isolates from the 2000 isolates.

Conclusion

Our data support the hypothesis that the 2000 human listeriosis outbreak was caused by aL. monocytogenesstrain that persisted in a food processing facility over 12 years and show that genome sequencing is a valuable and feasible tool for retrospective epidemiological analyses. Short-term evolution ofL. monocytogenesin non-controlled environments appears to involve limited diversification beyond plasmid gain or loss and prophage diversification, highlighting the importance of phages in bacterial evolution.
The extracellular EXO protein mediates cell expansion in Arabidopsis leaves
Authors: Schröder Florian , Lisso Janina , Lange Peggy , Müssig Carsten
Published: February 2009

Background

The EXO (EXORDIUM) gene was identified as a potential mediator of brassinosteroid (BR)-promoted growth. It is part of a gene family with eight members in Arabidopsis. EXO gene expression is under control of BR, and EXO overexpression promotes shoot and root growth. In this study, the consequences of loss of EXO function are described.

Results

The exo loss of function mutant showed diminished leaf and root growth and reduced biomass production. Light and scanning electron microscopy analyses revealed that impaired leaf growth is due to reduced cell expansion. Epidermis, palisade, and spongy parenchyma cells were smaller in comparison to the wild-type. The exo mutant showed reduced brassinolide-induced cotyledon and hypocotyl growth. In contrast, exo roots were significantly more sensitive to the inhibitory effect of synthetic brassinolide. Apart from reduced growth, exo did not show severe morphological abnormalities. Gene expression analyses of leaf material identified genes that showed robust EXO-dependent expression. Growth-related genes such as WAK1, EXP5, and KCS1, and genes involved in primary and secondary metabolism showed weaker expression in exo than in wild-type plants. However, the vast majority of BR-regulated genes were normally expressed in exo. HA- and GFP-tagged EXO proteins were targeted to the apoplast.

Conclusion

The EXO gene is essential for cell expansion in leaves. Gene expression patterns and growth assays suggest that EXO mediates BR-induced leaf growth. However, EXO does not control BR-levels or BR-sensitivity in the shoot. EXO presumably is involved in a signalling process which coordinates BR-responses with environmental or developmental signals. The hypersensitivity of exo roots to BR suggests that EXO plays a diverse role in the control of BR responses in the root.
Cytoplasmic CXCR4 expression in breast cancer: induction by nitric oxide and correlation with lymph node metastasis and poor prognosis
Authors: Yasuoka Hironao , Tsujimoto Masahiko , Yoshidome Katsuhide , Nakahara Masaaki , Kodama Rieko , Sanke Tokio , Nakamura Yasushi
Published: February 2009

Background

Lymph nodes constitute the first site of metastasis for most malignancies, and the extent of lymph node involvement is a major criterion for evaluating patient prognosis. The CXC chemokine receptor 4 (CXCR4) has been shown to play an important role in lymph node metastasis. Nitric oxide (NO) may also contribute to induction of metastatic ability in human cancers.

Methods

CXCR4 expression was analyzed in primary human breast carcinoma with long-term follow-up. The relationship between nitrotyrosine levels (a biomarker for peroxynitrate formation from NO in vivo) and lymph node status, CXCR4 immunoreactivity, and other established clinico-pathological parameters, as well as prognosis, was analyzed. Nitrite/nitrate levels and CXCR4 expressions were assessed in MDA-MB-231 and SK-BR-3 breast cancer cell lines after induction and/or inhibition of NO synthesis.

Results

CXCR4 staining was predominantly cytoplasmic; this was observed in 50%(56/113) of the tumors. Cytoplasmic CXCR4 expression was significantly correlated with nitrotyrosine levels and lymph node metastasis. Kaplan-Meier survival curves showed that cytoplasmic CXCR4 expression was associated with reduced disease-free and overall survival. In multivariate analysis, cytoplasmic CXCR4 expression emerged as a significant independent predictor for overall and disease-free survival. Cytoplasmic expression of functional CXCR4 in MDA-MB-231 and SK-BR-3 cells was increased by treatment with the NO donor DETA NONOate. This increase was abolished by L-NAME, an inhibitor of NOS.

Conclusion

Our data showed a role for NO in stimulating cytoplasmic CXCR4 expression in vitro. Formation of the biomarker nitrotyrosine was also correlated with CXCR4 expression and lymph node metastasis in vivo. In addition, cytoplasmic CXCR4 expression may serve as a significant prognostic factor for long-term survival in breast cancer.
Coding region structural heterogeneity and turnover of transcription start sites contribute to divergence in expression between duplicate genes
Authors: Park Chungoo , Makova Kateryna D
Published: February 2009

Background

Gene expression divergence is one manifestation of functional differences between duplicate genes. Although rapid accumulation of expression divergence between duplicate gene copies has been observed, the driving mechanisms behind this phenomenon have not been explored in detail.

Results

We examine which factors influence expression divergence between human duplicate genes, utilizing the latest genome-wide data sets. We conclude that the turnover of transcription start sites between duplicate genes occurs rapidly after gene duplication and that gene pairs with shared transcription start sites have significantly higher expression similarity than those without shared transcription start sites. Moreover, we find that most (55%) duplicate gene pairs do not retain the same coding sequence structure between the two duplicate copies and this also contributes to divergence in their expression. Furthermore, the proportion of aligned sequences in cis-regulatory regions between the two copies is positively correlated with expression similarity. Surprisingly, we find no effect of copy-specific transposable element insertions on the divergence of duplicate gene expression.

Conclusions

Our results suggest that turnover of transcription start sites, structural heterogeneity of coding sequences, and divergence of cis-regulatory regions between copies play a pivotal role in determining the expression divergence of duplicate genes.
Transgenic Expression of Insulin-Response Element Binding Protein-1 in β-Cells Reproduces Type 2 Diabetes
Authors: Villafuerte Betty C. , Barati Michelle T. , Song Ying , Moore Joseph P. , Epstein Paul N. , Portillo Jessica
Published: February 2009

Recent evidence supports the idea that insulin signaling through the insulin receptor substrate/phosphatidyl-inositol 3-kinase/Akt pathway is involved in the maintenance of β-cell mass and function. We previously identified the insulin-response element binding protein-1 (IRE-BP1) as an effector of insulin-induced Akt signaling in the liver, and showed that the 50-kDa carboxyl fragment confers the transcriptional activity of this factor. In this investigation we found that IRE-BP1 is expressed in the α, β, and δ-cells of the islets of Langerhans, and is localized to the cytoplasm in β-cells in normal rats, but is reduced and redistributed to the islet cell nuclei in obese Zucker rats. To test whether IRE-BP1 modulates β-cell function and insulin secretion, we used the rat insulin II promoter to drive expression of the carboxyl fragment in β-cells. Transgenic expression of IRE-BP1 in FVB mice increases nuclear IRE-BP1 expression, and produces a phenotype similar to that of type 2 diabetes, with hyperinsulinemia, hyperglycemia, and increased body weight. IRE-BP1 increased islet type I IGF receptor expression, potentially contributing to the development of islet hypertrophy. Our findings suggest that increased gene transcription mediated through IRE-BP1 may contribute to β-cell dysfunction in insulin resistance, and allow for the hypothesis that IRE-BP1 plays a role in the pathophysiology of type 2 diabetes.
Accelerated Recovery from Acute Hypoxia in Obese Mice Is Due to Obesity-Associated Up-Regulation of Interleukin-1 Receptor Antagonist
Authors: Sherry Christina L. , Kim Stephanie S. , Freund Gregory G.
Published: February 2009

The proinflammatory consequences of obesity are thought to be due, in part, to macrophage infiltration into adipose tissue. There are, however, potential antiinflammatory consequences of obesity that include obesity-associated up-regulation of IL-1 receptor antagonist (IL-1RA). Here we show that obesity-associated up-regulation of IL-1RA speeds recovery from hypoxia. We found that high-fat diet-fed (HFD) mice recovered from acute hypoxia 5 times faster than normal-diet-fed (ND) mice. HFD mice had a 10-fold increase in serum IL-1RA when compared with ND mice. White adipose tissue (WAT) was a significant source of IL-RA, generating 330 ± 77 pg/mg protein in HFD mice as compared with 15 ± 5 pg/mg protein in ND mice. Peritoneal macrophages isolated from HFD mice showed little difference in IL-1RA production when compared with ND mice, but WAT macrophages from HFD mice generated 11-fold more IL-1RA than those from ND mice. When ND mice were given an ip transfer of the stromal vascular fraction portion of WAT from HFD mice, serum IL-1RA increased 836% and recovery from acute hypoxia was faster than in mice that did not receive a stromal vascular fraction transfer. To determine whether IL-1RA was important to this accelerated recovery, ND mice were administered exogenous IL-1RA prior to hypoxia, and their recovery matched that of HFD mice. Inversely, when IL-1RA was immunoabsorbed in HFD mice with IL-1RA antiserum, recovery from acute hypoxia was attenuated. Taken together these data demonstrate that HFD-induced obesity speeds recovery from hypoxia due to obesity-associated up-regulation of IL-1RA.
Crucial Roles for Interactions between MLL3/4 and INI1 in Nuclear Receptor Transactivation
Authors: Lee Seunghee , Kim Dae-Hwan , Goo Young Hwa , Lee Young Chul , Lee Soo-Kyung , Lee Jae W.
Published: February 2009

Nuclear receptor (NR) transactivation involves multiple coactivators, and the molecular basis for how these are functionally integrated needs to be determined to fully understand the NR action. Activating signal cointegrator-2 (ASC-2), a transcriptional coactivator of many NRs and transcription factors, forms a steady-state complex, ASCOM (for ASC-2 complex), which contains histone H3-lysine-4 (H3K4) methyltransferase MLL3 or its paralog MLL4. Here, we show that ASCOM requires a functional cross talk with the ATPase-dependent chromatin remodeling complex Swi/Snf for efficient NR transactivation. Our results reveal that ASCOM and Swi/Snf are tightly colocalized in the nucleus and that ASCOM and Swi/Snf promote each other’s binding to NR target genes. We further show that the C-terminal SET domain of MLL3 and MLL4 directly interacts with INI1, an integral subunit of Swi/Snf. Our mutational analysis demonstrates that this interaction underlies the mutual facilitation of ASCOM and Swi/Snf recruitment to NR target genes. Importantly, this study uncovers a specific protein-protein interaction as a novel venue to couple two distinct enzymatic coactivator complexes during NR transactivation.
Salvaging Legal Personhood: Melville's Benito Cereno
Authors: DeLombard Jeannine Marie
Published: February 2009

DeLombard's essay departs from previous legally oriented readings of Benito Cereno by foregrounding not the title character's mysterious deposition but the novella's hitherto neglected series of contracts in order to interpret Herman Melville's only sustained literary portrayal of slavery through contemporaneous changes in contract law. Surveying the numerous legal documents that accumulate within and between the novella and its source text, Amasa Delano's Narrative of Voyages and Travels in the Northern and Southern Hemispheres (1817), the essay compares contracts and testimony to demonstrate how, instead of corroborating the legal personhood of their agents, these amassed textual assertions of civil agency cumulatively deauthorize text and author alike. The insistent temporality of law (and with it, narrative) ensures that, rather than affirming autonomous selfhood, such legal and extralegal acts of testifying and contract making document its absence.
Interracial Sexual Abuse and Legal Subjectivity in Antebellum Law and Literature
Authors: Stone Andrea
Published: February 2009

Representations of the sexual abuse of enslaved women merit a specificity of analysis that has so far eluded scholars of American literature and culture. The definition of legal character in this context calls for further study. Stone addresses the peculiar legal conundrum in which enslaved women found themselves when suffering the abuse of slaveholders. These women's shifting legal subject-positions posed theoretical problems within this particular power relationship, as the boundary distinguishing the law's treatment of slaves as property and persons blurred. An enslaved woman's admittedly slender potential civil protection as property was eroded when her abuser was simultaneously her owner. This shift in her protections produced a rift in her legal subjectivity through which systems of terror could operate legitimately. Stone closely examines Harriet Jacobs's Incidents in the Life of a Slave Girl (1865) in conjunction with the 1855 trial of Celia, an executed murderous slave, to compare specific literary and legal interpretations of North Carolina and Missouri slave law against a more general understanding of slaves' legal “double character” to argue that both women, through criminal acts, negotiated legal and literary conventions in their pursuit of legal subjectivity. Comparing a legal case and a literary text extends scholarship on literary treatments of antebellum crime to determine how both women challenged early American legal and cultural understandings of black criminality.
Fugitive Obscura: Runaway Slave Portraiture and Early Photographic Technology
Authors: Blackwood Sarah
Published: February 2009

This essay expands the vital but limited critical focus on the importance (practical and thematic) of textual literacy in slave narratives and other writings that appeared in the African American press in order to apprehend more clearly how these writers, working with words during a profoundly visual cultural moment, argued for a visual literacy that both denied the indexical power of white visual practices and embraced the power of the image to make injustice visible. Blackwood's analysis focuses on how texts by Frederick Douglass and Harriet Jacobs explore the representational capacity of a variety of prephotographic visual technologies, including portraiture, woodcuts, stereotypes, and the camera obscura. Douglass and Jacobs lived in the midst of a photographic revolution. Douglass repeatedly commented on photographic technology and celebrated its democratic potential. But both writers also devoted sustained attention in their texts to pre- or nonphotographic forms of visual representation. In so doing, they articulate a major, yet understudied, argument about the intersections between visual and textual representation during the period. In letters, editorials, and slave narratives, Douglass and Jacobs dramatize the interplay between the objective and illusionist potential of visual technologies. By embracing and remaining skeptical of the truthful qualities of the photographic image, the fugitive notice, and the slave narrative itself, Douglass and Jacobs enact a complicated form of resistance that alters our understandings of antebellum African American aesthetic production and the history of nineteenth-century visual culture more generally.
Free Soil and the Abolitionist Forests of Frederick Douglass's “The Heroic Slave”
Authors: Newman Lance
Published: February 2009

In the 1850s, Frederick Douglass set out to nurture emergent antislavery commitments within the most advanced political milieu of the antebellum decade, the Free Soil movement. Douglass developed a protoenvironmentalist critique of capitalism's alienation of workers from the land, arguing that liberty achieved its truest expression when free people mixed their labor with nature in the pursuit of self-reliance. Democratic access to arable land was a precondition of real emancipation, which required reversing capitalism's expropriation of the commons. Douglass fictionalized these ideas in his only novella, “The Heroic Slave” (1853), in which Madison Washington, leader of the 1841 Creole mutiny, declares his independence in a forest glade that functions as a chapel of natural rights. This kind of radical republican pastoralism also shapes My Bondage, My Freedom (1855). The trope's polemical function is especially apparent when it is contrasted retrospectively with The Narrative of the Life of Frederick Douglass, an American Slave (1845), in which nature is a paralyzing wilderness rather than a theater of self-emancipation. Ecocriticism has failed so far to engage substantially with black cultures of nature. Part of the problem may be that the lithified historical experience of slavery in rural settings has prevented black writers from developing ecocentric ways of thinking. Douglass's integration of radical pastoralism into abolitionist rhetoric is not only a spotlight example of an alternative black tradition and experience of nature, it also showcases the organic connection between the struggles for social and environmental justice.
“Be Cautious of the Word `Rebel'”: Race, Revolution, and Transnational History in Martin Delany's Blake; or, The Huts of America
Authors: Doolen Andy
Published: February 2009

Doolen examines the interrelationship between transnationalist ideology and the African American experience in Martin Delany's novel Blake; or, The Huts of America. In the antebellum struggle against slavery and racism, abolitionists considered fiction less effective than more factual narrative forms. However, Doolen argues that Martin Delany uses the novel form to identify how the fictions of white supremacy established the terms and categories of U.S. historiography. Recognizing that white-authored histories helped maintain the institutions of slavery, Delany attempts to remove African Americans from a nationalist discourse that automatically referred their appeals for racial justice back to a failed white revolutionary project. Doolen argues that the transnational shift that structures Blake—a movement between the United States and Cuba—constituted Delany's rejection of American Revolutionary time and space. By the time of the novel's abrupt ending, Delany had developed a hemispheric context for black liberation that cannot be traced back to the eighteenth-century corruptions of American republicanism. Finally, Doolen makes a case for Blake's literary complexity by emphasizing the nuanced relationship between novelistic and historical writing. In the process, Doolen challenges the standard chronology of African American literary history in which abolitionism's political, rhetorical, and formulaic constraints supposedly hindered the development of a fictional tradition prior to Emancipation.
Space, Time, and Story Tracks: Contemporary Practices of Topographic Memory in the Palikur Territory of Arukwa, Amapá, Brazil
Authors: Green Lesley J. F. , Green David R.
Published: February 2009

Using data collected during ethnographic fieldwork in the Palikur lands known as Arukwa along the Rio Urucauá in the Área Indígena do Uaçá, in Amapá, Brazil, we seek to expand current understandings of Arawakan oral forms of mapping that involve the listing of place-names. This article argues that the practice demonstrates a form of cartographic imagination that is based on a different theorization of the relationship between space and time. Contrasting the formal technology of cartography with the Palikur performative representations of “spatiotemporality,” this article argues that the former approach is inadequate to the task of understanding the practice of listing place-names insofar as it separates body, temporality, and sky from place. Moreover, the spatiotemporal approach described indexes not one but multiple temporalities, including the autobiographical, ecological, astronomical, genealogical, and historical. Drawing on the notion of “topokinetic memory” described by neuroscientist Alain Berthoz (2000) and on ethnographic material collected during a journey on the Rio Urucauá, this analysis distinguishes between story maps as the practice of representational memory of space (such as the listing of landmarks on routes) and “story tracks” as performances of orientation that accompany the telling of stories about journeys, or along them. Proposing that both modes of memory are important in everyday life, we argue that the story track constitutes a practice of topographic memory that relies on the perspective of earth, sky, and underworld afforded by the moving, perceiving, conscious, and responsive person. Understood in this way, the listing of place-names is a form of cartographic imagination that incorporates history, geography, astronomy, ethics, and the self.
Urea transporter and glutamine synthetase regulation and localization in gulf toadfish gill
Authors: McDonald M. Danielle , Vulesevic Branka , Perry Steve F. , Walsh Patrick J.
Published: February 2009

The goal of the present study was to investigate the role of circulating cortisol and urea in the transcriptional regulation of branchial glutamine synthetase (GS), which incorporates NH3 into glutamate to form glutamine, and the toadfish urea transporter, tUT, which is involved in urea excretion across the gill of the gulf toadfish. GS (of which there are two isoforms, LGS and GGS) and tUT mRNA expression and activity were measured in toadfish exposed to treatments that would induce variable stress responses. In addition, the role of circulating urea in tUT regulation was investigated by infusing toadfish with urea alone or in combination with intraperitoneal injection of RU486, a corticosteroid type II receptor antagonist. There was a 4.8-fold upregulation in the mRNA expression of the gill-specific GS isoform(GGS) in response to cortisol infusion and a similar upregulation in the more ubiquitous isoform (LGS). Furthermore, there was a significant 1.9-fold and 3.3-fold upregulation in the mRNA expression of the toadfish urea transporter,tUT, in response to stress through crowding or exogenous cortisol loading through infusion, respectively. In addition, tUT was found to have a urea-sensitive component to transcriptional regulation that was independent of circulating cortisol concentrations. However, the changes measured in mRNA expression of GGS, LGS and tUT did not correspond with changes in protein activity. To determine the cell type(s) involved in glutamine production and urea excretion, we attempted to localize GGS, LGS and tUT using in situ hybridization. This study is the first to show that GGS and tUT expression appear to occur in gill mitochondria-rich cells of toadfish,suggesting that these cells play a combined glutamine production and urea excretion role, which may have implications for predator avoidance.
Skeletal muscle fiber types in the ghost crab,Ocypode quadrata:implications for running performance
Authors: Perry Michael J. , Tait Jennifer , Hu John , White Scott C. , Medler Scott
Published: February 2009

Ghost crabs possess rapid running capabilities, which make them good candidates for comparing invertebrate exercise physiology with that of more extensively studied vertebrates. While a number of studies have examined various aspects of running physiology and biomechanics in terrestrial crabs,none to date have defined the basic skeletal muscle fiber types that power locomotion. In the current study, we investigated skeletal muscle fiber types comprising the extensor and flexor carpopodite muscles in relation to running performance in the ghost crab. We used kinematic analyses to determine stride frequency and muscle shortening velocity and found that both parameters are similar to those of comparably sized mammals but slower than those observed in running lizards. Using several complementary methods, we found that the muscles are divided into two primary fiber types: those of the proximal and distal regions possess long sarcomeres (6.2±2.3 μm) observed in crustacean slow fibers and have characteristics of aerobic fibers whereas those of the muscle mid-region have short sarcomeres (3.5±0.4 μm)characteristic of fast fibers and appear to be glycolytic. Each fiber type is characterized by several different myofibrillar protein isoforms including multiple isoforms of myosin heavy chain (MHC), troponin I (TnI), troponin T(TnT) and a crustacean fast muscle protein, P75. Three different isoforms of MHC are differentially expressed in the muscles, with fibers of the mid-region always co-expressing two isoforms at a 1:1 ratio within single fibers. Based on our analyses, we propose that these muscles are functionally divided into a two-geared system, with the aerobic fibers used for slow sustained activities and the glycolytic mid-region fibers being reserved for explosive sprints. Finally, we identified subtle differences in myofibrillar isoform expression correlated with crab body size, which changes by several orders of magnitude during an animal's lifetime.
Losing stability: tail loss and jumping in the arboreal lizardAnolis carolinensis
Authors: Gillis Gary B. , Bonvini Lauren A. , Irschick Duncan J.
Published: February 2009

Voluntary loss of an appendage, or autotomy, is a remarkable behavior that is widespread among many arthropods and lower vertebrates. Its immediate benefit, generally escape from a predator, is balanced by various costs,including impaired locomotor performance, reproductive success and long-term survival. Among vertebrates, autotomy is most widespread in lizards, in which tail loss has been documented in close to 100 species. Despite numerous studies of the potential costs of tail autotomy in lizards, none have focused on the importance of the tail in jumping. Using high-speed video we recorded jumps from six lizards (Anolis carolinensis) both before and after removing 80% of the tail to test the hypothesis that tail loss has a significant effect on jumping kinematics. Several key performance metrics, including jump distance and takeoff velocity, were not affected by experimental tail removal,averaging 21 cm and 124 cm s–1, respectively, in both tailed and tailless lizards. However, in-air stability during jumping was greatly compromised after tail removal. Lizards without tails rotated posteriorly more than 30 deg., on average, between takeoff and landing (and sometimes more than 90 deg.) compared with an average of 5 deg. of rotation in lizards with intact tails. Such exaggerated posterior rotation prevents coordinated landing, which is critical for animals that spend much of their time jumping to and from small branches. This work augments recent experiments demonstrating the importance of the tail as a mid-air stabilizer during falling in geckos, and emphasizes new and severe functional costs associated with tail autotomy in arboreal lizards.
A complex mechanism of call recognition in the katydid Neoconocephalus affinis (Orthoptera: Tettigoniidae)
Authors: Bush Sarah L. , Beckers Oliver M. , Schul Johannes
Published: February 2009

Acoustic pattern recognition is important for bringing together males and females in many insect species. We used phonotaxis experiments on a walking compensator to study call recognition in the katydid Neoconocephalus affinis, a species with a double-pulsed call and an atypically slow pulse rate for the genus. Call recognition in this species is unusual because females require the presence of two alternating pulse amplitudes in the signal. A Fourier analysis of the stimulus-envelopes revealed that females respond only when both the first and second harmonics of the AM spectrum are of similar amplitude. The second harmonic is generated by the amplitude difference between the two pulses making up a pulse-pair. Females respond to double pulses that have been merged into a single pulse only if this amplitude modulation is preserved. Further experiments suggest that females use a resonance mechanism to recognize the pulse rate of the call, supporting a neural model of rate recognition in which periodic oscillations in membrane potential are used to filter the pulse rate of the signal. Our results illustrate how a reduction in pulse rate extends the opportunities for females to evaluate fine-scale temporal properties of calls, and provide further evidence for the importance of oscillatory membrane properties in temporal processing. The results are discussed with regard to evolutionary changes in call recognition mechanisms within the genus.
Service Cancellation and Competitive Refund Policy
Authors: Guo Liang
Published: February 2009

Although previous research demonstrates the profitability of partial refund policies in a monopoly setting, there is a certain lack of ubiquity in practice about these refunds in competitive service markets. This raises the question of how a partial refund policy may work and whether it is even sustainable in a competitive environment. This study investigates how competition may influence the profitability and the equilibrium choice of refund policies. It is shown that partial refunds may endogenously change the nature of strategic interaction between service providers from local monopolies into a competition regime, which moderates the gains from exploiting the efficiency-enhancing effect of partial refunds. A whole range of pure-strategy equilibria can be obtained as a result of the interplay between the efficiency-improving and the competition-intensifying effects. When the capacity is small (large) such that the efficiency-improving (the competition-intensifying) effect is dominant, both firms in equilibrium follow identical partial (zero) refund policies. Moreover, interestingly, the symmetric firms may end up in an asymmetric equilibrium in which one firm follows a partial refund policy and the other adopts a zero refund policy.
Oral Cancer in Appalachia
Authors: Casto Bruce C. , Sharma Smita , Fisher James L. , Knobloch Thomas J. , Agrawal Amit , Weghorst Christopher M.
Published: February 2009

Oral cancer accounts for 2.3% of malignancies in the U.S. and has one of the lowest five-year survival rates. An examination of oral cancer in Appalachia was motivated by the high incidence of lung and bronchial cancers in Appalachian states, the risk factors for which overlap with those for oral cancer. The incidence and mortality rates for oral cancer in 13 Appalachian states and the relative frequency of presumptive risk factors were examined and compared with national rates, using data from the National Program of Cancer Registries, Surveillance Epidemiology and End Results, Behavioral Risk Factor Surveillance System, the Appalachian Regional Commission, and the National Health Interview Survey. Combined incidence rates for oral cancer were higher in six of 12 Appalachian states, and mortality rates higher in 10 of 13, compared with the national average. Smoking was more prevalent than the national average in nine of 13 states, whereas alcohol consumption was the same or less in 11 Appalachian states. Only five of 13 states averaged fewer than the recommended five or more servings per day of fruits and vegetables.
Explaining Racial Differences in Prenatal Care Initiation and Syphilis Screening Among Medicaid-covered Pregnant Women
Authors: Adams E. Kathleen , Gavin Norma I. , Raskind-Hood Cheryl , Tao Guoyu
Published: February 2009

Sexually transmitted diseases and their outcomes disproportionately affect non-Hispanic Blacks who also receive later prenatal care. We used a sample of low-income pregnant women insured by Medicaid to assess racial disparities in the receipt of first trimester prenatal care and any as well as early (by 2nd trimester) syphilis screening. We used an older but unique file of linked 1995 Georgia Medicaid claims and Pregnancy Risk Assessment Monitoring System (PRAMS) births (n = 1,096) to test the relative explanatory power of factors contained in administrative versus survey data. Using administrative data, we found non-Hispanic Blacks were less likely than non-Hispanic Whites to receive first trimester care but more likely to be screened. Adding in PRAMS survey data eliminated these differences. Having an outpatient department as usual source of care was a key factor. This may reflect unmeasured characteristics of minorities and their neighborhoods or differences in screening practices across provider settings.
A Syphilis Control Intervention Targeting Black and Hispanic Men Who Have Sex with Men
Authors: Sánchez John Paul , Lowe Carla , Freeman Millicent , Burton William , Sánchez Nelson Felix , Beil Robert
Published: February 2009

There are no documented syphilis control efforts targeting Black and Hispanic men who have sex with men (MSM) despite recent syphilis outbreaks among MSM and the disparate burden of syphilis among minorities. Methods . A syphilis control intervention, named the DL STATS PARTY, was designed to promote syphilis testing among minority MSM, through a sexual health and general well-being framework. Results . Of the 461 MSM with complete intake data, the average age was 27.0, 44.7% were Black, 42.7% were Hispanic, 67.9% had sex with two or more partners in the previous six months, and 28.4% reported sex with a female in the previous six months. Although Blacks accessed fewer overall services and physically invasive services, race/ethnicity was not a factor in choosing to be tested for syphilis. Conclusion . The DL STATS PARTY promoted syphilis testing among at-risk Black and Hispanic MSM. The program conforms to the CDC Recommended Steps to Mobilizing the Community to Address Syphilis and has the potential to be an example for other U.S. metropolitan areas.
Household Instability, Area Poverty, and Obesity in Urban Mothers and Their Children
Authors: Chambers Earle C. , Duarte Cristiane S. , Yang Frances M.
Published: February 2009

Fragile Families and Wellbeing Study (FFS) data were analyzed to examine the relationships between obesity, household instability, and area poverty in urban mothers and their children (N = 1,449). The FFS was conducted in 20 U.S. cities between 2001 and 2004. Household instability was defined as a tenuous home environment where certain psychosocial and economic constraints are present. Area poverty was determined according to the 2000 U.S. Census. Relative weight increased with level of household instability in mothers but not in children. Mothers with the highest level of household instability within areas of low poverty (i.e., relatively little poverty) were more likely than others to be obese (Odds Ratio = 1.8, 95% CI 1.2–2.6). Household instability was not associated with overweight in children. These results suggest that home stability should be considered as a possible risk factor for obesity in mothers with infant children, particularly those residing in low poverty areas.