Showing papers by "University of California published in 2009"

Implementation Research in Mental Health Services: an Emerging Science with Conceptual, Methodological, and Training challenges

Abstract: One of the most critical issues in mental health services research is the gap between what is known about effective treatment and what is provided to consumers in routine care. Concerted efforts are required to advance implementation science and produce skilled implementation researchers. This paper seeks to advance implementation science in mental health services by over viewing the emergence of implementation as an issue for research, by addressing key issues of language and conceptualization, by presenting a heuristic skeleton model for the study of implementation processes, and by identifying the implications for research and training in this emerging field.

Finite-sample sizes of johansen's likelihood ratio tests for cointegration

Abstract: This study examines the finite-sample bias of S. Johansen's likelihood ratio tests for cointegration using the Monte Carlo method. Response surface analysis is employed to obtain approximations to the finite-sample critical values and illustrate the individual roles of the sample size, the dimension of the variable system, and the lag order in determining the finite-sample bias of Johansen's tests. The study further shows the importance of lag length selection for Johansen's tests and the performance of standard lag selection criteria in choosing the proper lag length is investigated. Monte Carlo results concerning the sensitivity of Johansen's tests to non-normal innovations are also reported. Copyright 1993 by Blackwell Publishing Ltd

Nicotine Chemistry, Metabolism, Kinetics and Biomarkers

Abstract: Nicotine underlies tobacco addiction, influences tobacco use patterns, and is used as a pharmacological aid to smoking cessation. The absorption, distribution and disposition characteristics of nicotine from tobacco and medicinal products are reviewed. Nicotine is metabolized primarily by the liver enzymes CYP2A6, UDPglucuronosyltransfease (UGT), and flavin-containing monooxygenase (FMO). In addition to genetic factors, nicotine metabolism is influenced by diet and meals, age, sex, use of estrogen-containing hormone preparations, pregnancy and kidney disease, other medications, and smoking itself. Substantial racial/ethnic differences are observed in nicotine metabolism, which are likely influenced by both genetic and environmental factors. The most widely used biomarker of nicotine intake is cotinine, which may be measured in blood, urine, saliva, hair, or nails. The current optimal plasma cotinine cut-point to distinguish smokers from non-smokers in the general US population is 3 ng ml−1. This cut-point is much lower than that established 20 years ago, reflecting less secondhand smoke exposure due to clear air policies and more light or occasional smoking.

Stem cell fate dictated solely by altered nanotube dimension

Abstract: Two important goals in stem cell research are to control the cell proliferation without differentiation and to direct the differentiation into a specific cell lineage when desired. Here, we demonstrate such paths by controlling only the nanotopography of culture substrates. Altering the dimensions of nanotubular-shaped titanium oxide surface structures independently allowed either augmented human mesenchymal stem cell (hMSC) adhesion or a specific differentiation of hMSCs into osteoblasts by using only the geometric cues, absent of osteogenic inducing media. hMSC behavior in response to defined nanotube sizes revealed a very dramatic change in hMSC behavior in a relatively narrow range of nanotube dimensions. Small (≈30-nm diameter) nanotubes promoted adhesion without noticeable differentiation, whereas larger (≈70- to 100-nm diameter) nanotubes elicited a dramatic stem cell elongation (≈10-fold increased), which induced cytoskeletal stress and selective differentiation into osteoblast-like cells, offering a promising nanotechnology-based route for uniqueorthopedics-related hMSC treatments.

Mechanics, malignancy, and metastasis: the force journey of a tumor cell.

Abstract: A cell undergoes many genetic and epigenetic changes as it transitions to malignancy. Malignant transformation is also accompanied by a progressive loss of tissue homeostasis and perturbations in tissue architecture that ultimately culminates in tumor cell invasion into the parenchyma and metastasis to distant organ sites. Increasingly, cancer biologists have begun to recognize that a critical component of this transformation journey involves marked alterations in the mechanical phenotype of the cell and its surrounding microenvironment. These mechanical differences include modifications in cell and tissue structure, adaptive force-induced changes in the environment, altered processing of micromechanical cues encoded in the extracellular matrix (ECM), and cell-directed remodeling of the extracellular stroma. Here, we review critical steps in this “force journey,” including mechanical contributions to tissue dysplasia, invasion of the ECM, and metastasis. We discuss the biophysical basis of this force journey and present recent advances in the measurement of cellular mechanical properties in vitro and in vivo. We end by describing examples of molecular mechanisms through which tumor cells sense, process and respond to mechanical forces in their environment. While our understanding of the mechanical components of tumor growth, survival and motility remains in its infancy, considerable work has already yielded valuable insight into the molecular basis of force-dependent tumor pathophysiology, which offers new directions in cancer chemotherapeutics.

Reconstruction of biochemical networks in microorganisms

Abstract: Systems analysis of metabolic and growth functions in microbial organisms is rapidly developing and maturing. Such studies are enabled by reconstruction, at the genomic scale, of the biochemical reaction networks that underlie cellular processes. The network reconstruction process is organism specific and is based on an annotated genome sequence, high-throughput network-wide data sets and bibliomic data on the detailed properties of individual network components. Here we describe the process that is currently used to achieve comprehensive network reconstructions and discuss how these reconstructions are curated and validated. This Review should aid the growing number of researchers who are carrying out reconstructions for particular target organisms.

Pretreatment assessment of resectable and borderline resectable pancreatic cancer: expert consensus statement.

Abstract: Preoperative Staging and Defining Resectability From a surgical perspective, the first objective in the management of suspected or confirmed pancreatic cancer is to determine the potential for resection. Routine exploratory laparotomy for the purpose of operatively determining resectability has been diminished by modern 3-D radiographic imaging, along with effective and sustainable nonoperative methods of palliation. Careful correlation between preoperative CT findings and surgical results has better-defined CT criteria for resectability. The critical aspects that need be evaluated in a thorough radiographic assessment are the presence or absence of peritoneal or hepatic metastases; the potential involvement of the SMV and portal vein and the relationship of these vessels and their tributaries to the tumor; the relationship of the tumor to the SMA, celiac axis, hepatic artery, and gastroduodenal artery; and the presence of any aberrant vascular anatomy. Unequivocal radiographic findings contraindicating resection include distant metastases, major venous thrombosis of the portal vein or SMV extending for several centimeters, and circumferential encasement of the SMA, celiac axis or proximal hepatic artery. Recent revisions of the National Comprehensive Cancer Network (NCCN) guidelines were an attempt to distinguish locally advanced unresectable tumors from potentially resectable tumors.22 Ambiguity exists in these guidelines because of the lack of clarity in defining clearly resectable situations from “borderline resectable” tumors and because of the subjective criteria used to define “borderline” tumors relative to locally advanced, unresectable lesions. The NCCN guidelines do offer a definition of what should be considered a radiographically resectable tumor. Patients without distant metastases and no evidence of tumor extension to the SMV and portal vein and clear fat planes around the celiac axis, the hepatic artery, and SMA should be categorized as having localized and resectable cancers. More refined and objective criteria have been proposed by the M. D. Anderson Cancer Center Pancreas Cancer Group in an attempt to better define the term “borderline resectable” and to guide treatment decisions regarding the use of neoadjuvant therapy and the high likelihood of vein resection and reconstruction as a means to improve the rate of a complete and margin-negative resection.23 Radiographic findings of tumor abutment on the portal vein or SMV with or without venous deformity, and limited encasement of the mesenteric vein and portal vein (i.e., short segment occlusion with suitable vessel for anastomosis above and below) represent the extent of venous involvement that would categorize a tumor as borderline resectable. Radiographic findings suggesting borderline arterial involvement as defined by M. D. Anderson Cancer Center include encasement of a short segment of the hepatic artery, without evidence of tumor extension to the celiac axis and/or tumor abutment of the SMA involving < 180° of the artery circumference. In patients without clinically important major comorbidities, and in the absence of radiographic findings to suggest metastatic disease or locally advanced unresectable disease as outlined above, surgical resection should be considered feasible and likely to be achievable. Whether these resections would result in a higher-than-expected rate of margin-positive resections, and whether such resections would affect survival would best be determined by careful examination of outcomes relative to extent of vascular involvement using objective criteria to determine categorization of extent of disease. Consensus Statement 1. Tumors considered localized and resectable should demonstrate the following: a. No distant metastases. b. No radiographic evidence of SMV and portal vein abutment, distortion, tumor thrombus, or venous encasement. c. Clear fat planes around the celiac axis, hepatic artery, and SMA. 2. Tumors considered borderline resectable include the following: a. No distant metastases. b. Venous involvement of the SMV/portal vein demonstrating tumor abutment with or without impingement and narrowing of the lumen, encasement of the SMV/portal vein but without encasement of the nearby arteries, or short segment venous occlusion resulting from either tumor thrombus or encasement but with suitable vessel proximal and distal to the area of vessel involvement, allowing for safe resection and reconstruction. c. Gastroduodenal artery encasement up to the hepatic artery with either short segment encasement or direct abutment of the hepatic artery, without extension to the celiac axis. d. Tumor abutment of the SMA not to exceed >180° of the circumference of the vessel wall.

Do Retail Trades Move Markets

Abstract: We study the trading of individual investors using transaction data and identifying buyer- or seller-initiated trades. We document four results: (1) Small trade order imbalance correlates well with order imbalance based on trades from retail brokers. (2) Individual investors herd. (3) When measured annually, small trade order imbalance forecasts future returns; stocks heavily bought underperform stocks heavily sold by 4.4 percentage points the following year. (4) Over a weekly horizon, small trade order imbalance reliably predicts returns, but in the opposite direction; stocks heavily bought one week earn strong returns the subsequent week, while stocks heavily sold earn poor returns.

Quantitative Evidence for Increasing Forest Fire Severity in the Sierra Nevada and Southern Cascade Mountains, California and Nevada, USA

Abstract: Recent research has concluded that forest wildfires in the western United States are becoming larger and more frequent. A more significant question may be whether the ecosystem impacts of wildfire are also increasing. We show that a large area (approximately 120000 km2) of California and western Nevada experienced a notable increase in the extent of forest stand-replacing (“high severity”) fire between 1984 and 2006. High severity forest fire is closely linked to forest fragmentation, wildlife habitat availability, erosion rates and sedimentation, post-fire seedling recruitment, carbon sequestration, and various other ecosystem properties and processes. Mean and maximum fire size, and the area burned annually have also all risen substantially since the beginning of the 1980s, and are now at or above values from the decades preceding the 1940s, when fire suppression became national policy. These trends are occurring in concert with a regional rise in temperature and a long-term increase in annual precipitation. A close examination of the climate–fire relationship and other evidence suggests that forest fuels are no longer limiting fire occurrence and behavior across much of the study region. We conclude that current trends in forest fire severity necessitate a re-examination of the implications of all-out fire suppression and its ecological impacts.

Feedback linearization vs. adaptive sliding mode control for a quadrotor helicopter

Abstract: This paper presents two types of nonlinear controllers for an autonomous quadrotor helicopter. One type, a feedback linearization controller involves high-order derivative terms and turns out to be quite sensitive to sensor noise as well as modeling uncertainty. The second type involves a new approach to an adaptive sliding mode controller using input augmentation in order to account for the underactuated property of the helicopter, sensor noise, and uncertainty without using control inputs of large magnitude. The sliding mode controller performs very well under noisy conditions, and adaptation can effectively estimate uncertainty such as ground effects.

Shape induced inhibition of phagocytosis of polymer particles.

Abstract: Purpose To determine if particle shape can be engineered to inhibit phagocytosis of drug delivery particles by macrophages, which can be a significant barrier to successful therapeutic delivery.

Surface molecular property modifications for poly(dimethylsiloxane) (PDMS) based microfluidic devices

Abstract: Fast advancements of microfabrication processes in past two decades have reached to a fairly matured stage that we can manufacture a wide range of microfluidic devices. At present, the main challenge is the control of nanoscale properties on the surface of lab-on-a-chip to satisfy the need for biomedical applications. For example, poly(dimethylsiloxane) (PDMS) is a commonly used material for microfluidic circuitry, yet the hydrophobic nature of PDMS surface suffers serious nonspecific protein adsorption. Thus the current major efforts are focused on surface molecular property treatments for satisfying specific needs in handling macro functional molecules. Reviewing surface modifications of all types of materials used in microfluidics will be too broad. This review will only summarize recent advances in nonbiofouling PDMS surface modification strategies applicable to microfluidic technology and classify them into two main categories: (1) physical approach including physisorption of charged or amphiphilic polymers and copolymers, as well as (2) chemical approach including self assembled monolayer and thick polymer coating. Pros and cons of a collection of available yet fully exploited surface modification methods are briefly compared among subcategories.

What is Corpus Linguistics

Abstract: Corpus linguistics is one of the fastest-growing methodologies in contemporary linguistics. In a conversational format, this article answers a few questions that corpus linguists regularly face from linguists who have not used corpus-based methods so far. It discusses some of the central assumptions (‘formal distributional differences reflect functional differences’), notions (corpora, representativity and balancedness, markup and annotation), and methods of corpus linguistics (frequency lists, concordances, collocations), and discusses a few ways in which the discipline still needs to mature. At a recent LSA meeting … [with an obvious bow to Frederick Newmeyer] Question: So, I hear you’re a corpus linguist. Interesting, I get to see more and more

Semiconductor nanocrystal probes for biological applications and process for making and using such probes

Abstract: A semiconductor nanocrystal compound and probe are described. The compound is capable of linking to one or more affinity molecules. The compound comprises (1) one or more semiconductor nanocrystals capable of, in response to exposure to a first energy, providing a second energy, and (2) one or more linking agents, having a first portion linked to the one or more semiconductor nanocrystals and a second portion capable of linking to one or more affinity molecules. One or more semiconductor nanocrystal compounds are linked to one or more affinity molecules to form a semiconductor nanocrystal probe capable of bonding with one or more detectable substances in a material being analyzed, and capable of, in response to exposure to a first energy, providing a second energy. Also described are processes for respectively: making the semiconductor nanocrystal compound; making the semiconductor nanocrystal probe; and treating materials with the probe.

Sexual stigma and sexual prejudice in the United States: a conceptual framework.

Abstract: In 1972, psychologist George Weinberg’s book, Society and the Healthy Homosexual , introduced readers to a new term, homophobia , and to the then-novel idea that hostility to homosexuality, rather than homosexuality itself, posed a threat to mental health (Weinberg, 1972 ; see also Herek, 2004) . The following year, the American Psychiatric Association’s Board of Directors declared that homosexuality is not inherently associated with mental illness and voted to remove it from the Diagnostic and Statistical Manual of Mental Disorders , or DSM (Bayer, 1987 ; Minton, 2002) . The American Psychological Association quickly endorsed the psychiatrists’ action and further urged mental health professionals “to take the lead in removing the stigma of mental illness that has long been associated with homosexual orientations” (Conger, 1975 , p. 633). Thus, a major cultural institution renounced its longstanding role in legitimating society’s stigmatization of homosexuality just when the psychological manifestations of such stigma were beginning to be redefined as a social problem. This historic confluence of events provides an appropriate starting point for the present chapter. The term homophobia has gained widespread usage since 1972, even as its limitations have become increasingly apparent. Chief among these is its construction of prejudice as an individual pathology. As I have explained elsewhere (Herek, 2004) , this clinically derived perspective limits our ability to understand hostility toward sexual minorities, both among individuals and in society at large. I have argued instead for the value of framing heterosexuals’ negative responses to sexual minorities in terms of sexual prejudice and of conceptualizing sexual prejudice as the internalization of societal stigma (Herek, 2000a, 2004, 2007 ; Herek, Chopp, & Strohl, 2007) . In the present chapter, I elaborate on these points and provide a more detailed framework than I have previously presented for conceptualizing both societal and individual reactions to homosexuality and sexual minorities in the United States. 1

Intense pulsed light sintering of copper nanoink for printed electronics

Abstract: An intense pulsed light (IPL) from a xenon flash lamp was used to sinter copper nanoink printed on low-temperature polymer substrates at room temperature in ambient condition. The IPL can sinter the copper nanoink without damaging the polymer substrates in extremely short time (2 ms). The microstructure of the sintered copper film was investigated using X-ray powder diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), X-ray micro tomography, and atomic force microscopy (AFM). The sintered copper film has a grainy structure with neck-like junctions. The resulting resistivity was 5 μΩ cm of electrical resistivity which is only 3 times as high as that of bulk copper. The IPL sintering technique allows copper nanoparticles to be used in inkjet printing on low-temperature substrates such as polymers in ambient conditions.

Toward the Development of Printable Nanowire Electronics and Sensors

Abstract: In recent years, there has been tremendous progress in the research and development of printable electronics on mechanically flexible substrates based on inorganic active components, which provide high performances and stable device operations at low cost. In this regard, various approaches have been developed for the direct transfer or printing of micro- and nanoscale, inorganic semiconductors on substrates. In this review article, we focus on the recent advancements in the large-scale integration of single crystalline, inorganic-nanowire (NW) arrays for electronic and sensor applications, specifically involving the contact printing of NWs at defined locations. We discuss the advantages, limitations, and the state-of-the-art of this technol- ogy, and present an integration platform for future printable, heteroge- neous-sensor circuitry based on NW parallel arrays.

Fair and balanced?: bias in bug-fix datasets

Abstract: Software engineering researchers have long been interested in where and why bugs occur in code, and in predicting where they might turn up next. Historical bug-occurence data has been key to this research. Bug tracking systems, and code version histories, record when, how and by whom bugs were fixed; from these sources, datasets that relate file changes to bug fixes can be extracted. These historical datasets can be used to test hypotheses concerning processes of bug introduction, and also to build statistical bug prediction models. Unfortunately, processes and humans are imperfect, and only a fraction of bug fixes are actually labelled in source code version histories, and thus become available for study in the extracted datasets. The question naturally arises, are the bug fixes recorded in these historical datasets a fair representation of the full population of bug fixes? In this paper, we investigate historical data from several software projects, and find strong evidence of systematic bias. We then investigate the potential effects of "unfair, imbalanced" datasets on the performance of prediction techniques. We draw the lesson that bias is a critical problem that threatens both the effectiveness of processes that rely on biased datasets to build prediction models and the generalizability of hypotheses tested on biased data.

Diversifying Science: Underrepresented Student Experiences in Structured Research Programs.

Abstract: Targeting four institutions with structured science research programs for undergraduates, this study focuses on how underrepresented students experience science. Several key themes emerged from focus group discussions: learning to become research scientists, experiences with the culture of science, and views on racial and social stigma. Participants spoke of essential factors for becoming a scientist, but their experiences also raised complex issues about the role of race and social stigma in scientific training. Students experienced the collaborative and empowering culture of science, exhibited strong science identities and high self-efficacy, while developing directed career goals as a result of “doing science” in these programs.

Asymptotics in ASEP with Step Initial Condition

Abstract: In previous work the authors considered the asymmetric simple exclusion process on the integer lattice in the case of step initial condition, particles beginning at the positive integers. There it was shown that the probability distribution for the position of an individual particle is given by an integral whose integrand involves a Fredholm determinant. Here we use this formula to obtain three asymptotic results for the positions of these particles. In one an apparently new distribution function arises and in another the distribution function F2 arises. The latter extends a result of Johansson on TASEP to ASEP, and hence proves KPZ universality for ASEP with step initial condition.

Influenza estacional en adultos y niños—Diagnóstico, tratamiento, quimioprofilaxis y control de brotes institucionales: Guías de práctica clínica de la Sociedad de Enfermedades Infecciosas de Estados Unidos de América

Abstract: 14 Universidad de Toronto, Ontario, Canada. Es importante advertir que, en las guo´as, no es posible tener en cuenta siempre las variaciones individuales que se presenten entre pacientes. Las guo´as no intentan reemplazar el criterio del medico respecto de pacientes en particular o cuadros clo´nicos especiales. La Sociedad de Enfermedades Infecciosas de Estados Unidos de America considera que la adhesion a estas guo´as es voluntaria y que la determinacion final sobre su aplicacion corresponde al medico conforme a la situacion individual de cada paciente. Los hallazgos y las conclusiones de este informe pertenecen a los autores y no representan, necesariamente, la postura oficial de los Centros para el Control y Prevencion de Enfermedades.

Would I lie to you? On social preferences and lying aversion

Abstract: This paper reinterprets the evidence on lying or deception presented in Gneezy (Am. Econ. Rev. 95(1):384–394, 2005). We show that Gneezy’s data are consistent with the simple hypothesis that people are one of two kinds: either a person will never lie, or a person will lie whenever she prefers the outcome obtained by lying over the outcome obtained by telling the truth. This implies that so long as lying induces a preferred outcome over truth-telling, a person’s decision of whether to lie may be completely insensitive to other changes in the induced outcomes, such as exactly how much she monetarily gains relative to how much she hurts an anonymous partner. We run new but broadly similar experiments to those of Gneezy in order to test this hypothesis. While we also confirm that there is an aversion to lying in our subject population, our data cannot reject the simple hypothesis described above either.

Youth Empowerment and High School Gay-Straight Alliances

Abstract: In the field of positive youth development programs, “empowerment” is used interchangeably with youth activism, leadership, civic participation and self-efficacy. However, few studies have captured what empowerment means to young people in diverse contexts. This article explores how youth define and experience empowerment in youth-led organizations characterized by social justice goals: high school Gay-Straight Alliances (GSAs). Through focus group interviews, fifteen youth leaders of GSAs from different regions of California explain what they think empowerment means and how they became empowered through their involvement with the GSA. Youth describe three inter-related dimensions of empowerment: personal empowerment, relational empowerment, and strategic empowerment through having and using knowledge. When these three dimensions are experienced in combination, GSA leaders have the potential for individual and collective empowerment as agents of social change at school. By understanding these youth’s perspectives on the meanings of empowerment, this article clarifies the conceptual arena for future studies of socially marginalized youth and of positive youth development.

Foliar water uptake: a common water acquisition strategy for plants of the redwood forest

Abstract: Evaluations of plant water use in ecosystems around the world reveal a shared capacity by many dif- ferent species to absorb rain, dew, or fog water directly into their leaves or plant crowns. This mode of water uptake provides an important water subsidy that relieves foliar water stress. Our study provides the first comparative evaluation of foliar uptake capacity among the dominant plant taxa from the coast redwood ecosystem of California where crown-wetting events by summertime fog frequently occur during an otherwise drought-prone season. Previous research demonstrated that the dominant overstory tree species, Sequoia sempervirens, takes up fog water by both its roots (via drip from the crown to the soil) and directly through its leaf surfaces. The present study adds to these early findings and shows that 80% of the dominant species from the redwood forest exhibit this foliar uptake water acquisition strategy. The plants studied include canopy trees, understory ferns, and shrubs. Our results also show that foliar uptake provides direct hydration to leaves, increasing leaf water content by 2-11%. In addition, 60% of redwood forest species investigated demonstrate noc- turnal stomatal conductance to water vapor. Such findings indicate that even species unable to absorb water directly into their foliage may still receive indirect benefits from nocturnal leaf wetting through suppressed transpiration. For these species, leaf-wetting events enhance the efficacy of nighttime re-equilibration with available soil water and therefore also increase pre-dawn leaf water potentials.

Structure of genetic diversity in the two major gene pools of common bean (Phaseolus vulgaris L., Fabaceae)

Abstract: Domesticated materials with well-known wild relatives provide an experimental system to reveal how human selection during cultivation affects genetic composition and adaptation to novel environments. In this paper, our goal was to elucidate how two geographically distinct domestication events modified the structure and level of genetic diversity in common bean. Specifically, we analyzed the genome-wide genetic composition at 26, mostly unlinked microsatellite loci in 349 accessions of wild and domesticated common bean from the Andean and Mesoamerican gene pools. Using a model-based approach, implemented in the software STRUCTURE, we identified nine wild or domesticated populations in common bean, including four of Andean and four of Mesoamerican origins. The ninth population was the putative wild ancestor of the species, which was classified as a Mesoamerican population. A neighbor-joining analysis and a principal coordinate analysis confirmed genetic relationships among accessions and populations observed with the STRUCTURE analysis. Geographic and genetic distances in wild populations were congruent with the exception of a few putative hybrids identified in this study, suggesting a predominant effect of isolation by distance. Domesticated common bean populations possessed lower genetic diversity, higher F(ST), and generally higher linkage disequilibrium (LD) than wild populations in both gene pools; their geographic distributions were less correlated with genetic distance, probably reflecting seed-based gene flow after domestication. The LD was reduced when analyzed in separate Andean and Mesoamerican germplasm samples. The Andean domesticated race Nueva Granada had the highest F(ST) value and widest geographic distribution compared to other domesticated races, suggesting a very recent origin or a selection event, presumably associated with a determinate growth habit, which predominates in this race.

Hybridization and the evolution of invasiveness in plants and other organisms

Abstract: Less than a decade ago, we proposed that hybridization could serve as a stimulus for the evolution of invasiveness in plants (Ellstrand and Schierenbeck Proc Nat Acad Sci USA 97:7043–7050, 2000). A substantial amount of research has taken place on that topic since the publication of that paper, stimulating the symposium that makes up this special issue. Here we present an update of this emergent field, based both on the papers in this volume and on the relevant literature. We reevaluate the lists that we presented in our earlier paper of reports in which hybridization has preceded the evolution of invasiveness. We discard a few cases that were found to be in error, published only as abstracts, or based on personal communication. Then we augment the list from examples in this volume and a supplementary literature search. Despite the omissions, the total number of cases has increased. Many have been strengthened. We add a list of cases in which there has been evidence that intra-taxon hybridization has preceded the evolution of invasiveness. We also provide a number of examples from organisms other than plants. We consider how our examples suggest mechanisms whereby hybridization may act to stimulate the evolution of invasiveness. Hybridization does not represent the only evolutionary pathway to invasiveness, but it is one that can explain why the appearance of invasiveness often involves a long lag time and/or multiple introductions of exotics.

Rail and property development in Hong Kong: Experiences and extensions

Abstract: Hong Kong has aggressively pursued transit value capture to finance railway infrastructure through its ‘Rail + Property’ development programme, or R+P. More than half of all income to the railway operators comes from property development. Most R+P projects focus on housing although all have some commercial development. Recent generation R+P projects have stressed pedestrian quality. This research shows this has in turn increased ridership and housing prices. An R+P station with a transit-oriented design averages 35 000 additional weekday passengers. Housing price premiums in the range of 5—30 per cent were found. Hong Kong’s R+P model, it is suggested, is well suited for financing rail infrastructure and advancing transit-oriented designs in the rapidly growing cities of mainland China.

Autonomous UAV path planning and estimation

Abstract: Unmanned aerial vehicles (UAVs) have shown promise in recent years for autonomous sensing. UAVs systems have been proposed for a wide range of applications such as mapping, surveillance, search, and tracking operations. The recent availability of low-cost UAVs suggests the use of teams of vehicles to perform sensing tasks. To leverage the capabilities of a team of vehicles, efficient methods of decentralized sensing and cooperative path planning are necessary. The goal of this work is to examine practical control strategies for a team of fixed-wing vehicles performing cooperative sensing. We seek to develop decentralized, autonomous control strategies that can account for a wide variety of sensing missions. Sensing goals are posed from an information theoretic standpoint to design strategies that explicitly minimize uncertainty. This work proposes a tightly coupled approach, in which sensor models and estimation objectives are used online for path planning.

Mathematics of cell motility: have we got its number?

Abstract: Mathematical and computational modeling is rapidly becoming an essential research technique complementing traditional experimental biological methods. However, lack of standard modeling methods, difficulties of translating biological phenomena into mathematical language, and differences in biological and mathematical mentalities continue to hinder the scientific progress. Here we focus on one area—cell motility—characterized by an unusually high modeling activity, largely due to a vast amount of quantitative, biophysical data, ‘modular’ character of motility, and pioneering vision of the area’s experimental leaders. In this review, after brief introduction to biology of cell movements, we discuss quantitative models of actin dynamics, protrusion, adhesion, contraction, and cell shape and movement that made an impact on the process of biological discovery. We also comment on modeling approaches and open questions.