The Role of Behavioral Dynamics in Determining the Patch Distributions of Interacting Species

The effect of the behavioral dynamics of movement on the population dynamics of interacting species in multipatch systems is studied. The behavioral dynamics of habitat choice used in a range of previous models are reviewed. There is very limited empirical evidence for distinguishing between these different models, but they differ in important ways, and many lack properties that would guarantee stability of an ideal free distribution in a single-species system. The importance of finding out more about movement dynamics in multispecies systems is shown by an analysis of the effect of movement rules on the dynamics of a particular two-species–two-patch model of competition, where the population dynamical equilibrium in the absence of movement is often not a behavioral equilibrium in the presence of adaptive movement. The population dynamics of this system are explored for several different movement rules and different parameter values, producing a variety of outcomes. Other systems of interacting species that may lack a dynamically stable distribution among patches are discussed, and it is argued that such systems are not rare. The sensitivity of community properties to individual movement behavior in this and earlier studies argues that there is a great need for empirical investigation to determine the applicability of different models of the behavioral dynamics of habitat selection

When Clients Complain: Bureaucratic Responsiveness in Large Federal Agencies

High error rates in entitlements and slow responses to client complaints by Federal agencies are analyzed from a r.arket-power frame of reference focusing on the relative powerlessness of agency clients in relation to agencies which hold monopolies of life sustaining benefits. Data from a survey of Members of Congress are presented to provide an estimate of error rates. Three alternative structural solutions to the problem of unresponsiveness are assessed, including increased congressional casework service, ombudsmen services, and use of Federal Information Centers to aid clients. Necessary quality control procedures to facilitate each solution are described

Hydra Effects in Stable Communities and Their Implications for System Dynamics

A hydra effect occurs when the mean density of a species increases in response to greater mortality. We show that, in a stable multispecies system, a species exhibits a hydra effect only if maintaining that species at its equilibrium density destabilizes the system. The stability of the original system is due to the responses of the hydra-effect species to changes in the other species’ densities. If that dynamical feedback is removed by fixing the density of the hydra-effect species, large changes in the community make-up (including the possibility of species extinction) can occur. This general result has several implications: (1) Hydra effects occur in a much wider variety of species and interaction webs than has previously been described, and may occur for multiple species, even in small webs; (2) conditions for hydra effects caused by predators (or diseases) often differ from those caused by other mortality factors; (3) introducing a specialist or a switching predator of a hydra-effect species often causes large changes in the community, which frequently involve extinction of other species; (4) harvest policies that attempt to maintain a constant density of a hydra-effect species may be difficult to implement, and, if successful, are likely to cause large changes in the densities of other species; and (5) trophic cascades and other indirect effects caused by predators of hydra-effect species can exhibit amplification of effects or unexpected directions of change. Although we concentrate on systems that are originally stable and models with no stage-structure or trait variation, the generality of our result suggests that similar responses to mortality will occur in many systems without these simplifying assumptions. In addition, while hydra effects are defined as responses to altered mortality, they also imply counterintuitive responses to changes in immigration and other parameters affecting population growth

Computing camera viewpoints in a robot work-cell

Automatically planning a camera viewpoint for tasks such as inspection in an active robot work-cell is a difficult problem. This paper discusses new methods for computing viewpoints which meet the feature detectability constraints of focus, field-of-view, visibility, and resolution. A theoretical outline of the method is presented, followed by experimental results and a discussion of future work

The Electronic Controls Used in a Search For Fractional Charges in Mercury Drops

At San Francisco State University, we have developed an Automatic Millikan Device (AMI)) for measuring the charge on small drops of Mercury. The device uses a standard atomic physics laboratory Millikan chamber, a piezoelectric driven ink-jet glass dropper, and a laser-photomultiplier system for tracking the motion of the drop. This paper describes the electronic control and error detection system used with the AMO. Signals from this system are sent to a microprocessor which controls the experiment. To this date (Dec 7, 1981), we have measured 175 micrograms of Hg and found no fractional charges in 1.05 x 1020 nucleons

Dynamic sensor planning

A method of extending the sensor planning abilities of the MVP (machine vision planning) system to plan viewpoints for monitoring a pre-planned robot task is described. The dynamic sensor planning system presented analyzes geometric models of the environment and of the planned motions of the robot, as well as optical models of the vision sensor. Using a combination of swept volumes and a temporal interval search technique, it computes a series of viewpoints, each of which provides a valid viewpoint for a different interval of the task. By mounting a camera on another manipulator, the viewpoints can be executed at appropriate times during the task so that there is always a robust view suitable for monitoring the task. Experimental results monitoring a simulated robot operation are presented, and directions for future research are discussed

Ebookness

Since the mid-2000s, the ebook has stabilized into an ontologically distinct form, separate from PDFs and other representations of the book on the screen. The current article delineates the ebook from other emerging digital genres with recourse to the methodologies of platform studies and book history. The ebook is modelled as three concentric circles representing its technological, textual and service infrastructure innovations. This analysis reveals two distinct properties of the ebook: a simulation of the services of the book trade and an emphasis on user textual manipulation. The proposed model is tested with reference to comparative studies of several ebooks published since 2007 and defended against common claims of ebookness about other digital textual genres

Transcriptome Analysis of Neisseria gonorrhoeae during Natural Infection Reveals Differential Expression of Antibiotic Resistance Determinants between Men and Women

Neisseria gonorrhoeae is a bacterial pathogen responsible for the sexually transmitted infection gonorrhea. Emergence of antimicrobial resistance (AMR) of N. gonorrhoeae worldwide has resulted in limited therapeutic choices for this infection. Men who seek treatment often have symptomatic urethritis; in contrast, gonococcal cervicitis in women is usually minimally symptomatic, but may progress to pelvic inflammatory disease. Previously, we reported the first analysis of gonococcal transcriptome expression determined in secretions from women with cervical infection. Here, we defined gonococcal global transcriptional responses in urethral specimens from men with symptomatic urethritis and compared these with transcriptional responses in specimens obtained from women with cervical infections and in vitro-grown N. gonorrhoeae isolates. This is the first comprehensive comparison of gonococcal gene expression in infected men and women. RNA sequencing analysis revealed that 9.4% of gonococcal genes showed increased expression exclusively in men and included genes involved in host immune cell interactions, while 4.3% showed increased expression exclusively in women and included phage-associated genes. Infected men and women displayed comparable antibiotic-resistant genotypes and in vitro phenotypes, but a 4-fold higher expression of the Mtr efflux pump-related genes was observed in men. These results suggest that expression of AMR genes is programed genotypically and also driven by sex-specific environments. Collectively, our results indicate that distinct N. gonorrhoeae gene expression signatures are detected during genital infection in men and women. We propose that therapeutic strategies could target sex-specific differences in expression of antibiotic resistance genes. IMPORTANCE Recent emergence of antimicrobial resistance of Neisseria gonorrhoeae worldwide has resulted in limited therapeutic choices for treatment of infections caused by this organism. We performed global transcriptomic analysis of N. gonorrhoeae in subjects with gonorrhea who attended a Nanjing, China, sexually transmitted infection (STI) clinic, where antimicrobial resistance of N. gonorrhoeae is high and increasing. We found that N. gonorrhoeae transcriptional responses to infection differed in genital specimens taken from men and women, particularly antibiotic resistance gene expression, which was increased in men. These sex-specific findings may provide a new approach to guide therapeutic interventions and preventive measures that are also sex specific while providing additional insight to address antimicrobial resistance of N. gonorrhoeae

Prognosis research strategy (PROGRESS) 1: a framework for researching clinical outcomes.

The PROGRESS series (www.progress-partnership.org) sets out a framework of four interlinked prognosis research themes and provides examples from several disease fields to show why evidence from prognosis research is crucial to inform all points in the translation of biomedical and health related research into better patient outcomes. Recommendations are made in each of the four papers to improve current research standards What is prognosis research? Prognosis research seeks to understand and improve future outcomes in people with a given disease or health condition. However, there is increasing evidence that prognosis research standards need to be improved Why is prognosis research important? More people now live with disease and conditions that impair health than at any other time in history; prognosis research provides crucial evidence for translating findings from the laboratory to humans, and from clinical research to clinical practice This first article introduces the framework of four interlinked prognosis research themes and then focuses on the first of the themes - fundamental prognosis research, studies that aim to describe and explain future outcomes in relation to current diagnostic and treatment practices, often in relation to quality of care Fundamental prognosis research provides evidence informing healthcare and public health policy, the design and interpretation of randomised trials, and the impact of diagnostic tests on future outcome. It can inform new definitions of disease, may identify unanticipated benefits or harms of interventions, and clarify where new interventions are required to improve prognosis

Search for Fractional Charges in Water

Results are presented from a search for fractional charges in water from a variety of natural sources. About 30 000 water drops have been measured, comprising 51 μg of water and dissolved materials. No evidence for fractional charge was seen