bluuebunny/crossref_metadata_2025 huggingface dataset:
Postchemotherapy Histiocyte-Rich Pseudotumor Involving the Spleen
Authors: Chandra Pranil , Wen Yong Hannah , Tuli Sandeep , Raphael Bruce G. , Amorosi Edward L. , Medeiros L. Jeffrey , Ibrahim Sherif
Published: August 2009

We report 2 cases of splenic postchemotherapy histiocyte-rich pseudotumor. Each patient had a history of diffuse large B-cell lymphoma, treated with multiagent chemotherapy. Computed tomography scans performed on both patients showed splenic masses. A positron emission tomography scan performed on 1 patient showed increased metabolic activity. The preoperative diagnosis in both patients was recurrent lymphoma, prompting splenectomy. The splenectomy specimens showed multiple, tan-white, firm nodules, up to 3.5 cm in diameter, that were histologically composed of central necrotic B cells (CD20+/CD3−), consistent with necrotic lymphoma, surrounded by numerous lipid-laden (xanthomatous) histiocytes. Clinical staging studies at the time of splenectomy showed no other sites of disease. We conclude that these histologic and immunophenotypic findings represent chemotherapy-induced tumor necrosis with a florid histiocytic reaction mimicking residual viable lymphoma. Others have used descriptive terminology or the term xanthomatous pseudotumor for these lesions that have been only rarely reported in the spleen previously.
A Basic Accounting of Variation in Municipal Solid‐Waste Generation at the County Level in Texas, 2006: Groundwork for Applying Metabolic‐Rift Theory to Waste Generation
Authors: Clement Matthew Thomas
Published: August 2009

Abstract  Environmental social scientists debate whether or not modern development reduces society's impact on the biosphere. The empirical research informing the discussion has not yet adequately examined the social determinants of municipal solid‐waste (MSW) generation, an increasingly relevant issue, both ecologically and sociologically. A primary problem for this research concerns the increasing exchange of MSW across state and county borders. A convenient way to avoid this problem is to examine variation between counties with landfills that service only the county in which the landfills are located. I applied this restriction to a cross‐sectional analysis of total MSW generated in Texas at the county level for 2006. Using robust regression, this study found that two basic measures of modern development, population per square mile and per capita income, are both positively related to total MSW generated at the county level and together explain about 73 percent of the variation in the dependent variable. The evidence corroborates the metabolic‐rift theory. The concentration of people onto smaller land areas, or urbanization, and increasing wealth in a capitalist economy contribute to the metabolic rupture between human society and the environment.
Paradoxes of Providing Rural Social Services: The Case of Homeless Youth
Authors: Edwards Mark Evan , Torgerson Melissa , Sattem Jennifer
Published: August 2009

Abstract  Economic and demographic changes in rural areas continue to introduce big‐city problems in small towns. These communities' ability and willingness to respond are likely to be influenced by the geography, culture, and array of organizations in rural places. But how these characteristics of rural places shape local response is hard to predict and as yet unexplored. This article reports data from interviews with social‐service providers and homeless youth in a rural county in the northwestern United States, drawing insights from both groups about the challenges of providing social services in rural places. Findings about drug use, sexual abuse and prostitution in rural communities illustrate how aspects of a rural context can influence the way small towns address social problems.
Are Conventional Farmers Conventional? Analysis of the Environmental Orientations of Conventional New Zealand Farmers*
Authors: Fairweather John R. , Hunt Lesley M. , Rosin Chris J. , Campbell Hugh R.
Published: August 2009

Abstract  Within the political economy of agriculture and agrofood literatures there are examples of approaches that reject simple dichotomies between alternatives and the mainstream. In line with such approaches, we challenge the assumption that alternative agriculture, and its attendant improved environmental practices, alternative management styles, less intensive approaches, and better approaches to animal and ecosystem welfare, is the only source of agricultural sustainability. This article uses national farm‐survey results for New Zealand's sheep and beef, dairy, and horticulture sectors to examine conventional farmers, measure their assessments of farming practices, and assess their environmental orientation. Analysis identifies a proenvironmental cluster of farmers in each sector characterized by a higher environmental‐orientation score and distinct ratings of other farm practices queried in the survey. We interpret the results in terms of the exposure of different agricultural sectors to the effects of market‐based, audited, best‐practice schemes. The presence of shades of “greenness” among conventional farmers has important implications for environmental management and for our understanding of the various and complex pathways toward the greening of agrofood systems.
Writing the New West: A Critical Review*
Authors: Robbins Paul , Meehan Katharine , Gosnell Hannah , Gilbertz Susan J.
Published: August 2009

Abstract A vast and growing interdisciplinary research effort has focused on the rise of the so‐called New West, purportedly the product of regional socioeconomic, political, and ecological upheavals in states like Montana and Colorado. Reviewing the growing research on this problem in sociology, economics, geography, and conservation science, this article identifies four central questions at the core of this diverse scholarship. Our review demonstrates that none of these central questions has generated consensus conclusions and that there is untapped potential for more structurally robust analyses of the drivers and outcomes of rapid change in the region. Indeed, supporting other analyses that have called the consistency of the region into question, our survey suggests the ways in which this region is not unique, but largely reflective of larger scale socioecological forces playing out in similar ways around the postindustrial world. We conclude, therefore, with a series of crucial questions, which may be unanswerable by assuming the “New West” as a coherent geography.
Conversion to Organic Dairy Production in the Netherlands: Opportunities and Constraints*
Authors: Smit Arnoud A.H. , Driessen Peter P.J. , Glasbergen Pieter
Published: August 2009

Abstract  Organic agriculture is perceived as being more sustainable than conventional agriculture. However, while there is a growing interest in, and market for, organic products, large‐scale conversion to organic agriculture is not taking place. Even though conversion from conventional to organic dairy production is not especially difficult in theory, conversion is slow in this specific sector. The conversion process to organic agriculture is often analyzed by investigating farmer motivations and attitudes. However, since modern agricultural production is organized in production chains, which are in turn subject to stakeholder influence, a wider focus that includes these interrelationships might provide new insights regarding the lagging conversion. Based on document analysis, policy analysis, and interviews, this article investigates opportunities for, and barriers to, conversion to organic dairy production in the Netherlands within the setting of the chain network. Opportunities and barriers are found at three levels within the chain network: the actor level, the chain level, and the network level. We conclude that, despite some involvement in organic production and a positive disposition toward it, the chain network is not ready for a large‐scale conversion.
The value of IGF1 estimation in adults with GH deficiency
Authors: Mukherjee A , Shalet S M
Published: August 2009

The GH/IGF1 system, like other endocrine systems, is dynamic and its activity changes with age and sexual maturation, and is influenced by body composition and other factors. A normal level of IGF1 does not exclude a diagnosis of GH deficiency (GHD) in adults, and the usefulness of IGF1 in the diagnosis of adult GHD has historically been confusing and contentious. The regulation of IGF1 secretion in adults is complex, and is not solely dependent on GH status with factors recognized to influence IGF1 status in patients with GHD including age, gender, exogenous estrogen therapy, prolactin status, and severity of GHD. The usefulness of IGF1 for monitoring treatment of GH disorders in adulthood is now widely accepted, especially as GH-dosing regimens for GHD have evolved from weight-based dosing (associated with overtreatment and side effects) to individualized dose–titration strategies, which maintain IGF1 within target limits. Sub-optimal replacement therapy may be associated with morbidity and mortality risk from a continuing state of functional GHD. Conversely, avoiding iatrogenic biochemical acromegaly is clearly important and other potential safety issues may be associated with a persistently high IGF1. Analysis and interpretation of IGF1 status therefore represent a useful diagnostic tool especially in the younger adult patients with severe GHD and an essential measurement for monitoring GH replacement in all adults with GHD. High-quality, method-specific reference ranges for IGF1 and a high degree of methodological consistency in the assay are essential for reliable comparison of results.
Assessment of quality of life in adult patients with GH deficiency: KIMS contribution to clinical practice and pharmacoeconomic evaluations
Authors: Koltowska-Häggström Maria , Mattsson Anders F , Shalet Stephen M
Published: August 2009

Quality of life (QoL) has emerged as an important construct that has found numerous applications across healthcare-related fields, ranging from research and clinical evaluation of treatment effects to pharmacoeconomic evaluations and global healthcare policy. Impairment of QoL is one of the key clinical characteristics in adult GHD and has been extensively studied in the Pfizer International Metabolic Database (KIMS). We provide summarized evidence on GH treatment effects for both clinical and health economic applications based on the KIMS data. The primary focus is on those aspects of QoL research that cannot be investigated in the traditional clinical trial setting, such as specific patient subgroups, cross-country comparisons and long-term follow-up. First, the impact of age, gender, disease onset, primary aetiology, extent of hypopituitarism, previous radiotherapy and obesity on QoL before and during long-term GH replacement is discussed. Secondly, the studies on QoL in relation to country-specific normative values are reviewed. Finally, health economic data derived from KIMS including both burden of disease and utility assessment are evaluated. We conclude that the wide spectrum of analyses performed on the KIMS data allows for practical application of the results not only to research and clinical practice but also to health policy and global medical decision making.
Cardiovascular risk factors in hypopituitary GH-deficient adults
Authors: Verhelst Johan , Abs Roger
Published: August 2009

Design

Data on lipids, body composition, and blood pressure (BP) from all published KIMS papers are summarized and compared with a literature review.

Results

KIMS data confirm and extend previous research showing that adults with GH deficiency (GHD) have an adverse cardiovascular risk profile. GHD patients have high levels of dyslipidemia, elevated body mass index, unfavorable waist-to-hip ratio and body composition, and a high risk of hypertension. These abnormalities are likely to explain the increased cardiovascular mortality observed in patients with hypopituitarism. When given GH replacement therapy, an improvement is seen in KIMS as well as earlier studies for lipid profile, body composition, and BP. The added value of the different KIMS papers over previous research is that KIMS involves a much larger number of patients, that lipid concentrations and IGF1 are measured in a single central laboratory, and that the effects of GH replacement therapy can be followed longer than the duration of earlier trials. By the large number of patients, KIMS gives insight into the effects of GH in different patients' subgroups such as elderly patients, patients with idiopathic GHD, patients with craniopharyngioma, patients after irradiation, and so on. In addition, KIMS has made it possible to calculate more exactly the influence of baseline parameters on these cardiovascular risk parameters and their response to GH.

Conclusions

Taken together, data from KIMS confirm earlier knowledge about the important benefits of GH replacement therapy, but also on the use of GH in specific subgroups such as isolated GHD, patients above 65 years, and patients after irradiation. No subgroup yet has been identified as not responding well to GH.
GH replacement in adults: interactions with other pituitary hormone deficiencies and replacement therapies
Authors: Filipsson Helena , Johannsson Gudmundur
Published: August 2009

Severe GH deficiency (GHD) in adults has been described as a clinical entity. However, some of the features associated with GHD could be due to unphysiological and inadequate replacement of other pituitary hormone deficiencies. This may be true for glucocorticoid replacement that lacks a biomarker making dose titration and monitoring difficult. Moreover, oral estrogen replacement therapy decreases IGF1 levels compared with the transdermal route, which attenuates the responsiveness to GH replacement therapy in women. In addition, in untreated female hypogonadism, oral estrogen may augment the features associated with GHD in adult women. Important interactions between the hormones used for replacing pituitary hormone deficiency occur. Introducing GH replacement may unmask both an incipient adrenal insufficiency and central hypothyroidism. Therefore, awareness and proper monitoring of these hormonal interactions are important in order to reach an optimal replacement therapy. This review will focus on the complex hormonal interactions between GH and other pituitary hormones in GHD and in GH replacement.
From isolated GH deficiency to multiple pituitary hormone deficiency: an evolving continuum – a KIMS analysis
Authors: Klose M , Jonsson B , Abs R , Popovic V , Koltowska-Häggström M , Saller B , Feldt-Rasmussen U , Kourides I
Published: August 2009

Objective

To describe baseline clinical presentation, treatment effects and evolution of isolated GH deficiency (IGHD) to multiple pituitary hormone deficiency (MPHD) in adult-onset (AO) GHD.

Design

Observational prospective study.

Methods

Baseline characteristics were recorded in 4110 patients with organic AO-GHD, who were GH naïve prior to entry into the Pfizer International Metabolic Database (KIMS; 283 (7%) IGHD, 3827 MPHD). The effect of GH replacement after 2 years was assessed in those with available follow-up data (133 IGHD, 2207 MPHD), and development of new deficiencies in those with available data on concomitant medication (165 IGHD, 3006 MPHD).

Results

IGHD and MPHD patients had similar baseline clinical presentation, and both groups responded similarly to 2 years of GH therapy, with favourable changes in lipid profile and improved quality of life. New deficiencies were observed in 35% of IGHD patients, which was similar to MPHD patients with one additional deficit other than GH. New deficiencies most often presented within the first year but were observed up to 6 years after GH commencement. Conversion of IGHD into MPHD was not predicted by aetiology, baseline characteristics, surgery or radiotherapy, whereas in MPHD additional deficits were predicted by age (P<0.001) and pituitary disease duration (P<0.01).

Conclusion

Both AO-IGHD and -MPHD patients have similar baseline clinical presentation and respond equally well to 2 years of GH replacement. Hypopituitarism in adults seems to be a dynamic condition where new deficiencies can appear years after the initial diagnosis, and careful endocrine follow-up of all hypopituitary patients, including those with IGHD, is warranted.
Aggressive pituitary adenomas occurring in young patients in a large Polynesian kindred with a germline R271W mutation in the AIP gene
Authors: Jennings Juliet E , Georgitsi Marianthi , Holdaway Ian , Daly Adrian F , Tichomirowa Maria , Beckers Albert , Aaltonen Lauri A , Karhu Auli , Cameron Fergus J
Published: August 2009

Objective

Mutations in the aryl hydrocarbon receptor-interacting protein (AIP) were recently shown to confer a pituitary adenoma predisposition in patients with familial isolated pituitary adenomas (FIPA). We report a large Samoan FIPA kindred from Australia/New Zealand with an R271W mutation that was associated with aggressive pituitary tumors.

Design and methods

Case series with germline screening of AIP and haplotype analyses among R271W families.

Results

This previously unreported kindred consisted of three affected individuals that either presented with or had first symptoms of a pituitary macroadenoma in late childhood or adolescence. The index case, a 15-year-old male with incipient gigantism and his maternal aunt, had somatotropinomas, and the maternal uncle of the index case had a prolactinoma. All tumors were large (15, 40, and 60 mm maximum diameter) and two required transcranial surgery and radiotherapy. All three affected subjects and ten other unaffected relatives were found to be positive for a germline R271W AIP mutation. Comparison of the single nucleotide polymorphism patterns among this family and two previously reported European FIPA families with the same R271W mutation demonstrated no common ancestry.

Conclusions

This kindred exemplifies the aggressive features of pituitary adenomas associated with AIP mutations, while genetic analyses among three R271W FIPA families indicate that R271W represents a mutational hotspot that should be studied further in functional studies.
Towards Control of Dendrimer Properties by Reversible Exchange of Termini: Synthesis and Characterization of Diverse Porphyrin Dendrimers
Authors: Shema‐Mizrachi Meital , Aharoni Anna , Iliashevsky Olga , Lemcoff N. Gabriel
Published: August 2009

Porphyrin dendrimers with boronic ester, aldehyde, and pyridil termini were synthesized and fully characterized. These dendrimers have the potential to change their physical and chemical properties by reversible alteration of the reactive terminal groups.
Encapsulation of Polyoxotungstate into Dendrimers by Ionic Bonding and Their Use As Oxidation Catalyst
Authors: Jahier Claire , Plault Lauriane , Nlate Sylvain
Published: August 2009

A family of 36‐armed dendrimers containing six internal amino groups was synthesized and used to incorporate polyoxometalates (POMs) into their structures by ionic bonding. Allyl‐terminated dendrimer 17 (with oxidizable end groups) and methylphenyl‐terminated dendrimer 18 (with non‐oxidizable end groups) were used for these studies. It was found that the electrostatic incorporation of the tri‐anionic POM [PO4{WO(O2)2}4]3− into the methylphenyl‐terminated dendrimer 18, in an acidic medium, leads to the dendritic POM hybrid 19, bearing two POM units in its structure. In contrast, attempts to encapsulate POMs into allyl‐terminated dendrimer 17 gave unsatisfactory results. Indeed, the epoxidation kinetics of the 36‐olefinic terminated dendrimer 17 was too slow, and the expected 36‐epoxy‐dendritic POM framework 20 was not obtained. Lengthening the reaction up to six hours led to the decomposition of POM species. The solubility in organic solvents of the dendritic POM hybrid 19, combined with its NMR and infrared data, indicate that POM units are clearly connected to the dendritic structure. The catalytic performance of this hybrid material in the oxidation of cyclooctene shows that the properties of POM are retained. The POM‐encapsulated dendrimer 19 was found to be an effective catalyst in the oxidation of cyclooctene.
Divergent Dendronization of Deep‐Cavity Cavitands to Tune Host Solubility
Authors: Giles Marco D. , Liu Simin , Emanuel Roy , Gibb Bruce , Grayson Scott
Published: August 2009

Resorcinarene‐based deep‐cavity cavitands (DCCs) are useful components in supramolecular chemistry because their extended cavity enables the encapsulation of relatively large guests. To provide H2O solubility, they have been modified with hydroxyl functionalized dendrons. This has been carried out by the divergent dendronization of aliphatic poly(ester) dendrons through the third dendritic generation. The resultant macromolecule demonstrated the desired H2O solubility.
Supramolecular Assemblies from Amphiphilic Dendrons for Sensing Metalloproteins through Pattern Generation
Authors: Savariar Elamprakash N. , Koppelman Jonathan , Thayumanavan Sankaran
Published: August 2009

Biaryl dendritic micelles have been used for generating fluorescence response patterns that are used for sensing metalloproteins. By varying the generation of the dendrimer and the encapsulated dye molecules, the differential receptors for four different metalloproteins have been created. The pattern obtained from these dendritic micelles indeed confirms that the combination of dendrimer generation and electronic energy levels of the fluorescent transducers can be used for generating analyte‐specific patterns.
Thermally Reversible Self‐Assembly of Double‐Hydrophilic Diblock Copolymers from Poly(N‐isopropylacrylamide) and Dendronized Polymethacrylates
Authors: Cheng Caixia , Schlüter A. Dieter , Zhang Afang
Published: August 2009

The self‐assembly behavior of double‐hydrophilic block copolymers, in which one block is a dendronized PMMA and the other consists of PNiPAM, is described. For certain samples of the first‐generation series, fully reversible formation of rather uniform spherical objects in the range of approximately 90 nm is observed by TEM, suggesting a vesicular assembly.
A Route to Water‐Soluble Molecularly Templated Nanoparticles Using Click Chemistry and Alkyne‐Functionalized Hyperbranched Polyglycerol
Authors: Zill Andrew T. , Zimmerman Steven C.
Published: August 2009

Cored polymeric nanoparticles were prepared using an adenosine template and allylated hyperbranched polyglycerols (HPGs). The HPGs contained a single alkyne that was capable of 1,3‐dipolar cycloaddition with a decaazido adenosine template to facilitate the rapid synthesis of HPGs containing a large number of allyl end‐groups. Ring closing metathesis (RCM) mediated cross‐linking at high dilution using a Hoveyda‐Grubbs catalyst produced single polymer nanoparticles containing a single template. These particles were rendered water‐soluble through treatment with osmium tetroxide and NMO co‐oxidant. After hydrolytic removal of the template, the nanoparticles were tested for their ability to bind a variety of nucleosides and nucleobases and showed a preference for purine bases over pyrimidine bases. This is the first reported use of hyperbranched polymers for the synthesis of monomolecularly imprinted polymers (mMIPs) as well as the first time monomolecular imprinting has been applied to a homogeneous aqueous system.
Phosphorus Functionalized Dendrimers and Hyperbranched Polymers: Is There a Need for Perfect Dendrimers in Catalysis?
Authors: Ribaudo Fabrizio , Van Leeuwen Piet W. N. M. , Reek Joost N. H.
Published: August 2009

In this paper we describe the facile and straightforward covalent functionalization of commercially available dendritic poly(propylenimine) and hyper‐branched poly(ethylenimine) with P‐containing functional groups. The P‐functionalized macromolecules have been applied as multivalent ligands in the Pd‐catalyzed allylic substitution reactions (batch and continuous process) using either morpholine or thiophenol as nucleophile. Palladium complexes of all described molecules are active in allylic substitution reactions. The PEI functionalized polymers appear more sensitive to small changes in the P/Pd ratio than the PPI analogues, but form catalysts that are more active. When used in a continuous flow process the macromolecules are completely retained by the nanofiltration membrane, while the catalytic activity decreases with time because of palladium depletion. This is more severe for the allylic thiolation, probably because of the stronger affinity of sulfur for palladium, facilitating palladium leaching.
HER2 Testing and Subsequent Trastuzumab Treatment for Breast Cancer in a Managed Care Environment
Authors: Barron John J. , Cziraky Mark J. , Weisman Thomas , Hicks David G.
Published: August 2009

Background.

Degree of physician adherence to 2001 guidelines recommending routine testing of human epidermal growth factor receptor 2 (HER2) status among newly diagnosed, recurrent, and metastatic breast cancer (BC) cases, and frequency of trastuzumab use in HER2-positive patients are not well documented.

Methods.

Patients newly diagnosed with BC managed by an identifiable hematologist/oncologist between June 1, 2005 and June 30, 2006 were identified from an administrative claims database of three health plans (n = 3,521). From these, a subset of 380 patients was identified for medical chart review. HER2 testing (occurrence, type of test used), HER2 status (positive, negative, unknown), and trastuzumab usage were evaluated.

Results.

HER2 testing occurred in 88% of all newly diagnosed patients with BC and in 98.1% of those with stage 1 or higher breast cancer (n = 322), for whom testing is recommended. Among those with HER2 testing performed (n = 335), 21.5% were positive (HER2+), 77.3% were negative (HER2−), and 1.2% were unknown. Of the 52 patients who used trastuzumab, only one patient did not have documented HER2 overexpression. Of the 45 HER2+ women who had stage 2 or higher BC, 13% did not receive trastuzumab.

Conclusions.

HER2 testing status was extremely high among newly diagnosed BC patients treated by hematologists/oncologists in a managed care environment. There was almost no evidence of inappropriate prescribing of trastuzumab, but 1 of every 7.5 patients with HER2-overexpressing stage 2 or higher breast cancer did not receive the agent.
Clinical Experience with Aurora Kinase Inhibitors: A Review
Authors: Boss David S. , Beijnen Jos H. , Schellens Jan H.M.
Published: August 2009

The aurora kinase family of serine/threonine kinases comprises three members, designated auroras A, B, and C. Auroras A and B are essential components of the mitotic pathway, ensuring proper chromosome assembly, formation of the mitotic spindle, and cytokinesis. The role of aurora C is less clear. Overexpression of aurora A and B has been observed in several tumor types, and has been linked with a poor prognosis of cancer patients. Several small molecules targeting aurora kinases A and B or both have been evaluated preclinically and in early phase I trials. In this review we aim to summarize the most recent advances in the development of aurora kinase inhibitors, with a focus on the clinical data.
Trabectedin
Authors: Chuk Meredith K. , Balis Frank M. , Fox Elizabeth
Published: August 2009

Learning Objectives

After completing this course, the reader will be able to: Enumerate the clinical indications for trabectedin therapy.Describe the mechanism of action and the pharmacokinetics of trabectedin.Analyze the toxicity profile and appraise the therapeutic effects associated with trabectedin.

This article is available for continuing medical education credit at CME.TheOncologist.com.
A reanalysis of competing hypotheses for the spread of the California sea otter
Authors: Smith Curtis A. , Giladi Itamar , Lee Young-Seon
Published: August 2009

From 1938 to 1972, the range of California sea otters (Enhydra lutris nereis) expanded with the northern and southern fronts spreading at rates of approximately 1.4 km/yr and 3.1 km/yr, respectively. J. A. Lubina and S. A. Levin proposed the following three factors to explain the large disparity in spread rates: (1) regional differences in dispersal; (2) regional differences in population growth; and (3) advection due to the known presence of a southerly flowing offshore current. While Lubina and Levin used a reaction–diffusion framework to argue for large differences in dispersal, our approach uses a stage‐structured integrodifference matrix model to show that relatively minor differences in survival provide a more parsimonious explanation for the disparity in spread rates; especially if the survival rates between the northern and southern groups differ in more than one life stage. The argument is made that many of the present estimates for otter survival rates span intervals wide enough to explain the different spread rates—even more so in the likely case that advection plays at least a minor role in otter movement.
Comparison of multidimensional fuzzy set ordination with CCA and DB‐RDA
Authors: Roberts David W.
Published: August 2009

Multidimensional fuzzy set ordination (MFSO) is an ordination algorithm based on the principles of fuzzy set theory that employs a dissimilarity matrix and environmental or experimental variables directly in the calculation of ordination coordinates. The objective is similar to constrained ordinations such as canonical correspondence analysis (CCA) and distance‐based redundancy analysis (DB‐RDA), although MFSO employs a different conceptual and algorithmic basis. Results from MFSO, CCA, and DB‐RDA are compared on four data sets to determine the relative ability of the methods to identify and quantify environmental variable effect sizes on community variability. Models were fit by best all‐subsets solutions and tested for significance by permutation tests. Methods were compared on the basis of variables selected and dimensionality of results and were evaluated on the basis of the correlation of the pair‐wise distances of the derived ordination solutions to a Bray‐Curtis dissimilarity matrix of the taxon data, and by cross‐comparisons of the inertia explained by the fitted or derived values substituted into DB‐RDA and CCA analyses.

MFSO and DB‐RDA achieved the highest correlation with the Bray‐Curtis dissimilarity matrix on one data set each, and they tied for highest correlation on the two other data sets (differences <1%). CCA tied for best on one data set, tied for second on another, and achieved the lowest correlation on two data sets. When substituting MFSO‐ and DB‐RDA‐derived values into CCA, MFSO results achieved higher inertia explained on two of the four data sets; MFSO and DB‐RDA achieved equivalent results on the other two. Substituting MFSO‐ or CCA‐derived or fitted values into DB‐RDA, MFSO results achieved higher inertia explained on all four data sets. While goodness‐of‐fit statistics were often similar across methods, the methods sometimes chose solutions of different dimensionality or employed different variables. In general, all algorithms performed well, finding relatively low‐dimensional solutions that achieved high correlation with the Bray‐Curtis dissimilarity matrix and explained significant amounts of inertia in the eigenanalyses. Considering both the correlation and substitution tests, MFSO achieved the best results of the three methods. DB‐RDA results were nearly as good as MFSO, however, and clearly superior to CCA.
Press perturbations and indirect effects in real food webs
Authors: Montoya JoséM. , Woodward Guy , Emmerson Mark C. , Solé Ricard V.
Published: August 2009

The prediction of the effects of disturbances in natural systems is limited by the general lack of knowledge on the strength of species interactions, i.e., the effect of one species on the population growth rate of another, and by the uncertainty of the effects that may be manifested via indirect pathways within the food web. Here we explored the consequences of changes in species populations for the remaining species within nine exceptionally well‐characterized empirical food webs, for which, unlike the vast majority of other published webs, feeding links have been fully quantified. Using the inverse of the Jacobian matrix, we found that perturbations to species with few connections have larger net effects (considering both direct and indirect pathways between two species) on the rest of the food web than do disturbances to species that are highly connected. For 40% of predator–prey links, predators had positive net effects on prey populations, due to the predominance of indirect interactions. Our results highlight the fundamental, but often counterintuitive, role of indirect effects for the maintenance of food web complexity and biodiversity.
Plant interactions are unimportant in a subarctic–alpine plant community
Authors: Mitchell Matthew G. E. , Cahill James F. , Hik David S.
Published: August 2009

We investigated whether plant interaction intensity in a subarctic–alpine meadow is important for determining community structure and species abundance. Using two common species as phytometers, we measured interaction intensity using a neighbor removal approach. Eight biotic and abiotic variables known to influence species abundance and community structure were measured, with regression trees used to examine how plant interactions and the biotic and abiotic variables were related to species evenness, richness, and phytometer spatial cover. A range of interactions was present, with both strong competition and facilitation present over small‐scale abiotic and biotic gradients. Despite the variation in interaction intensity, it was generally unrelated to either community structure or phytometer cover. In other words, plant interactions were intense in many cases but were not important to community structure. This may be due to the prevalence of clonal species in this system and the influence of previous year's interactions on plant survival and patterns of community structure. These results also suggest how conflicting theories of the role of competition in unproductive environments may be resolved. Our findings suggest that plant interactions may be intense in reducing individual growth, while simultaneously not important in the context of community structure. Plant interactions need to be viewed and tested relative to other factors and stresses to accurately evaluate their importance in plant communities, with continued differentiation between the intensity of plant interactions and their relative importance in communities.
Random, top‐down, or bottom‐up coexistence of parasites: malaria population dynamics in multi‐parasitic settings
Authors: Chaves Luis Fernando , Kaneko Akira , Pascual Mercedes
Published: August 2009

Epidemiological models concerned with the control of malaria using interventions such as bed nets and vaccines increasingly incorporate realistic aspects of malaria biology. The increasing complexity of these models limits their ability to abstract ecological processes and to address questions on the regulation of population dynamics using time‐series data, particularly in regards to interactions between different pathogens and the regulatory role of innate (bottom‐up) and acquired (top‐down) immunity. We use a theoretical framework to test hypotheses on the importance of population‐level immunity and parasite abundance in regulating the population dynamics of malaria. We use qualitative loop analyses to examine the sign of the interaction between Plasmodium falciparum and P. vivax at the population level, and we discuss implications of this sign for the within‐host regulation of parasites. Our analyses of monthly malaria time‐series data from the island of Espirito Santo, Vanuatu (1983–1997), show that the dynamics of P. falciparum are not sensitive to P. vivax, whereas infections by the latter increase in response to those of the former. These results support a differential use of resources inside the hosts, a resource–consumer interaction between hosts and their immune system, and within‐host regulation of parasites. Finally, our results emphasize the need to better understand factors regulating malaria dynamics before developing control strategies and call for the use of control strategies directed at the interruption of transmission, such as vector control and the use of bed nets.
Salt marsh ecosystem biogeochemical responses to nutrient enrichment: a paired 15N tracer study
Authors: Drake D. C. , Peterson Bruce J. , Galván Kari A. , Deegan Linda A. , Hopkinson Charles , Johnson J. Michael , Koop-Jakobsen K. , Lemay Lynsey E. , Picard Christian
Published: August 2009

We compared processing and fate of dissolved NO3− in two New England salt marsh ecosystems, one receiving natural flood tide concentrations of ∼1–4 μmol NO3−/L and the other receiving experimentally fertilized flood tides containing ∼70–100 μmol NO3−/L. We conducted simultaneous 15NO3− (isotope) tracer additions from 23 to 28 July 2005 in the reference (8.4 ha) and fertilized (12.4 ha) systems to compare N dynamics and fate. Two full tidal cycles were intensively studied during the paired tracer additions. Resulting mass balances showed that essentially 100% (0.48–0.61 mol NO3‐N·ha−1·h−1) of incoming NO3− was assimilated, dissimilated, sorbed, or sedimented (processed) within a few hours in the reference system when NO3− concentrations were 1.3–1.8 μmol/L. In contrast, only 50–60% of incoming NO3− was processed in the fertilized system when NO3− concentrations were 84–96 μmol/L; the remainder was exported in ebb tidewater. Gross NO3− processing was ∼40 times higher in the fertilized system at 19.34–24.67 mol NO3‐N·ha−1·h−1. Dissimilatory nitrate reduction to ammonium was evident in both systems during the first 48 h of the tracer additions but <1% of incoming 15NO3− was exported as 15NH4+. Nitrification rates calculated by 15NO3− dilution were 6.05 and 4.46 mol·ha−1·h−1 in the fertilized system but could not be accurately calculated in the reference system due to rapid (<4 h) NO3− turnover. Over the five‐day paired tracer addition, sediments sequestered a small fraction of incoming NO3−, although the efficiency of sequestration was 3.8% in the reference system and 0.7% in the fertilized system. Gross sediment N sequestration rates were similar at 13.5 and 12.6 mol·ha−1·d−1, respectively. Macrophyte NO3− uptake efficiency, based on tracer incorporation in aboveground tissues, was considerably higher in the reference system (16.8%) than the fertilized system (2.6%), although bulk uptake of NO3− by plants was lower in the reference system (1.75 mol NO3−·ha−1·d−1) than the fertilized system (∼10 mol NO3−·ha−1·d−1). Nitrogen processing efficiency decreased with NO3− load in all pools, suggesting that the nutrient processing capacity of the marsh ecosystem was exceeded in the fertilized marsh.
Intraguild predation in a structured habitat: distinguishing multiple‐predator effects from competitor effects
Authors: Schmitt Russell J. , Holbrook Sally J. , Brooks Andrew J. , Lape Jennifer C. P.
Published: August 2009

The ability to forecast community dynamics requires, among other things, an understanding of indirect effects and nonlinearities in webs of interacting species, together with knowledge of how habitat structure mediates interactions. We explored these aspects for a coral reef system in Moorea, French Polynesia, involving intraguild predation where the shared damselfish prey (juvenile yellowtail dascyllus Dascyllus flavicaudus) and two species of intraguild (IG) prey (the ambush predators arc‐eye hawkfish Paracirrhites arcatus and red‐spotted coral crab Trapezia rufopunctata) shelter together in branching Pocilloporid corals for protection from mobile IG predators. Field experiments revealed that both IG prey had strong adverse effects on survivorship of juvenile damselfish, but that the dominant underlying process was competition for enemy‐free space and not direct consumption. In this case, the combined effect of hawkfish and crabs did not result in either risk enhancement or risk reduction for the damselfish. Similarly, the combined influence of IG predators and IG prey on the shared prey also was indistinguishable from that expected from their independent effects. Habitat structure weakened the IG‐prey–IG‐predator interaction; IG prey were much stronger space competitors with damselfish than resource competitors with IG predators. As a consequence, there was not a trophic cascade where damselfish benefited by the adverse effect of IG predators on hawkfish or coral crabs. These results highlight the manner by which habitat structure can mediate species interactions and emphasize the need to understand the underlying mechanisms.
Quantitative synthesis of context dependency in ant–plant protection mutualisms
Authors: Chamberlain Scott A. , Holland J. Nathaniel
Published: August 2009

Context dependency, variation in the outcome of species interactions with biotic and abiotic conditions, is increasingly considered ubiquitous among mutualisms. Despite several qualitative reviews of many individual empirical studies, there has been little quantitative synthesis examining the generality of context dependency, or conditions that may promote it. We conducted a meta‐analysis of ant–plant protection mutualisms to examine the generality of context‐dependent effects of ants on herbivory and plant performance (growth, reproduction). Our results show that ant effects on plants are not generally context dependent, but instead are routinely positive and rarely neutral, as overall effect sizes of ants in reducing herbivory and increasing plant performance were positive and significantly greater than 0. The magnitude of these positive effects did vary, however. Variation in plant performance was not explained by the type of biotic or abiotic factor examined, including plant rewards (extrafloral nectar, food bodies, domatia), ant species richness, plant growth form, or latitude. With the exception of plant growth form, these factors did contribute to the effects of ants in reducing herbivory. Reductions in herbivory were greater for plants with than without domatia, and greatest for plants with both domatia and food bodies. Effect sizes of ants in reducing herbivory decreased, but remained positive, with latitude and ant species richness. Effect sizes in reducing herbivory were greater in tropical vs. temperate systems. Although ant–plant interactions have been pivotal in the study of context dependency of mutualisms, our results, along with other recent meta‐analyses, indicate that context dependency may not be a general feature of mutualistic interactions. Rather, ant–plant protection mutualisms appear to be routinely positive for plants, and only occasionally neutral.
Extra‐regional residence time as a correlate of plant invasiveness: European archaeophytes in North America
Authors: La Sorte Frank A. , Pyšek Petr
Published: August 2009

Human activities have degraded biogeographical barriers to dispersal resulting in the spread and naturalization of increasing numbers of nonnative invasive species. One correlate of invasiveness within a region is residence time or time since introduction. Plant species that were introduced into Europe prior to AD 1500 (European archaeophytes) that were subsequently introduced into North America provide a unique opportunity to examine the effect of extra‐regional residence time (i.e., residence time that occurred in a nonnative region before a species was introduced into a new region). Here, we examine how nonnative species with extensive extra‐regional residence times have affected beta diversity among states in the contiguous United States of America based on an analysis of occupancy and distance decay of similarity. State floras contained an average of 3106 ± 922 species (mean ± SD) with 2318 ± 757 species classified as native, 180 ± 43 species as European archaeophyte, and 608 ± 236 species as other exotic with no European archaeophyte association. For European archaeophytes, 42% were identified as noxious weeds in the United States with 8% identified as agricultural and 14% as natural‐area weeds (20%, 2%, and 13% for other exotics, respectively). In strong contrast to natives and other exotics, European archaeophytes were more widespread and presented weaker distance‐decay patterns. Thus, European archaeophytes were more likely to become noxious weeds, particularly within agricultural areas, and were associated with significant losses in beta diversity. We suggest that this outcome is a consequence of extra‐regional residence time, which allowed for the selection of species or the evolution of traits that favored the colonization of arable habitats associated with early agricultural activities in Europe, habitats that are widespread, resource rich, and uniformly distributed in the United States. Our findings suggest that a long‐term trajectory can be established, with residence time in one region building biological and geographical potential, often in direct association with anthropogenic activities, for invasions in new regions. When predicting or managing for potential invaders within a region, identifying extra‐regional residence time and its consequences is critical when assessing a species' long‐term invasive potential.
Methods for assessing movement path recursion with application to African buffalo in South Africa
Authors: Bar-David Shirli , Bar-David Israel , Cross Paul C. , Ryan Sadie J. , Knechtel Christiane U. , Getz Wayne M.
Published: August 2009

Recent developments of automated methods for monitoring animal movement, e.g., global positioning systems (GPS) technology, yield high‐resolution spatiotemporal data. To gain insights into the processes creating movement patterns, we present two new techniques for extracting information from these data on repeated visits to a particular site or patch (“recursions”). Identification of such patches and quantification of recursion pathways, when combined with patch‐related ecological data, should contribute to our understanding of the habitat requirements of large herbivores, of factors governing their space‐use patterns, and their interactions with the ecosystem.

We begin by presenting output from a simple spatial model that simulates movements of large‐herbivore groups based on minimal parameters: resource availability and rates of resource recovery after a local depletion. We then present the details of our new techniques of analyses (recursion analysis and circle analysis) and apply them to data generated by our model, as well as two sets of empirical data on movements of African buffalo (Syncerus caffer): the first collected in Klaserie Private Nature Reserve and the second in Kruger National Park, South Africa.

Our recursion analyses of model outputs provide us with a basis for inferring aspects of the processes governing the production of buffalo recursion patterns, particularly the potential influence of resource recovery rate. Although the focus of our simulations was a comparison of movement patterns produced by different resource recovery rates, we conclude our paper with a comprehensive discussion of how recursion analyses can be used when appropriate ecological data are available to elucidate various factors influencing movement. Inter alia, these include the various limiting and preferred resources, parasites, and topographical and landscape factors.