A strategy planner for NASA robotics applications

Automatic strategy or task planning is an important element of robotics systems. A strategy planner under development at Goddard Space Flight Center automatically produces robot plans for assembly, disassembly, or repair of NASA spacecraft from computer aided design descriptions of the individual parts of the spacecraft

Design and implementation of a compliant robot with force feedback and strategy planning software

Force-feedback robotics techniques are being developed for automated precision assembly and servicing of NASA space flight equipment. Design and implementation of a prototype robot which provides compliance and monitors forces is in progress. Computer software to specify assembly steps and makes force feedback adjustments during assembly are coded and tested for three generically different precision mating problems. A model program demonstrates that a suitably autonomous robot can plan its own strategy

Comparison of the COBE FIRAS and DIRBE Calibrations

We compare the independent FIRAS and DIRBE observations from the COBE in the wavelength range 100-300 microns. This cross calibration provides checks of both data sets. The results show that the data sets are consistent within the estimated gain and offset uncertainties of the two instruments. They show the possibility of improving the gain and offset determination of DIRBE at 140 and 240 microns.Comment: Accepted for publication in the Astrophysical Journal 11 pages, plus 3 figures in separate postscript files. Figure 3 has three part

The Cosmic Infrared Background: Measurements and Implications

The cosmic infrared background records much of the radiant energy released by processes of structure formation that have occurred since the decoupling of matter and radiation following the Big Bang. In the past few years, data from the Cosmic Background Explorer mission provided the first measurements of this background, with additional constraints coming from studies of the attenuation of TeV gamma-rays. At the same time there has been rapid progress in resolving a significant fraction of this background with the deep galaxy counts at infrared wavelengths from the Infrared Space Observatory instruments and at submillimeter wavelengths from the Submillimeter Common User Bolometer Array instrument. This article reviews the measurements of the infrared background and sources contributing to it, and discusses the implications for past and present cosmic processes.Comment: 61 pages, incl. 9 figures, to be published in Annual Reviews of Astronomy and Astrophysics, 2001, Vol. 3

Organizaciones locales en el Área Hortícola Bonaerense: la acción colectiva como respuesta al conflicto social

A partir del relevamiento de diferentes formas asociativas en el área hortícola bonaerense, intentaremos observar su vinculación con el Estado y la comunidad productiva que integran. Considerando la organización local como forma de resolución de problemas comunes, resultado del conflicto social, se intentará ahondar en estos conceptos y en ejemplos etnográficos para entender la relación entre ellos. El presente trabajo incluye avances de una investigación en curso1 que estudia el papel de las organizaciones locales en la evolución de la actividad hortícola bonaerense. A partir del estudio de casos, vemos la construcción de espacios colectivos e identificamos el rol político de las organizaciones, en función de la praxis y los conflictos sociales inherentes, en relación con las posibilidades de movilidad social. Partiendo del estudio de casos, se han sistematizado los modelos de gestión existentes dentro de las organizaciones, considerando su relación con las posibilidades de movilidad social. Relevamos y clasificamos su heterogeneidad e identificamos su rol político, consistente no en la conquista o ejercicio del poder del Estado, sino en la generación de influencia y la incidencia en cuestiones públicas a través de su accionar concreto. Analizamos la trama organizacional local, conformada por la articulación entre organizaciones gremiales y económico-productivas por un lado y otras instituciones del área, por otro. La estrategia metodológica es el estudio de casos múltiples elegidos por un muestreo teórico, relevados mediante trabajo de campo etnográfico. Para el análisis utilizamos el método comparativo, cotejando casos similares, intentando captar la definición que los actores hacen de su situación y el significado que dan a sus conductas. Intentaremos desentrañar si la organización social puede convertirse en una de las respuestas posibles de los agentes, ante instancias de conflicto socioeconómico.Fil: Diaz Galan, Laura S.. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Núcleo Argentino de Antropología Rural; ArgentinaFil: Diez Brodd, Ana Carolina. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Núcleo Argentino de Antropología Rural; ArgentinaFil: Feito, Maria Carolina. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Núcleo Argentino de Antropología Rural; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Kostnads-nyttoanalys som verktyg f\uf6r prioritering av efterbehandlingsinsatser.

F\uf6r att uppn\ue5 milj\uf6m\ue5let En giftfri milj\uf6 kr\ue4vs att en stor m\ue4ngd f\uf6rorenade omr\ue5den tas om hand och efterbehandlas. Kostnaden f\uf6r att \ue5tg\ue4rda de mest f\uf6rorenade omr\ue5dena har av Naturv\ue5rdsverket ber\ue4knats uppg\ue5 till ca 60 miljarder kronor. Ett problem \ue4r dock att samh\ue4llets resurser f\uf6r s\ue5dana insatser \ue4r begr\ue4nsade. Det \ue4r d\ue4rf\uf6r viktigt att utveckla verktyg f\uf6r att prioritera bland t\ue4nkbara insatser s\ue5 att en sund hush\ue5llning sker av samh\ue4llets begr\ue4nsade resurser. En m\uf6jlig ansats till prioritering \ue4r att g\uf6ra samh\ue4llsekonomiska bed\uf6mningar av potentiella efterbehandlingsinsatser. Syftet \ue4r d\ue5 att unders\uf6ka om en viss insats \ue4r samh\ue4llsekonomiskt l\uf6nsam och helst \ue4ven analysera vilka insatser som \ue4r mer samh\ue4llsekonomiskt l\uf6nsamma \ue4n andra. Ett vedertaget verktyg f\uf6r samh\ue4llsekonomiska analyser \ue4r Kostnads-nyttoanalys (KNA). Metoden har dock \ue4nnu f\ue5tt begr\ue4nsad anv\ue4ndning inom svenskt milj\uf6arbete, och s\ue4rskilt vad g\ue4ller arbete med f\uf6rorenade omr\ue5den. I detta projekt inom Naturv\ue5rdsverkets kunskapsprogram H\ue5llbar sanering beskrivs hur KNA kan anv\ue4ndas f\uf6r att g\uf6ra samh\ue4lls\uacekonomiska bed\uf6mningar av efter\uacbehandlings\ue5tg\ue4rder

Staphylococcus aureus persisters are associated with reduced clearance in a catheter-associated biofilm infection

BackgroundStaphylococcus aureus causes a wide variety of infections, many of which are chronic or relapsing in nature. Antibiotic therapy is often ineffective against S. aureus biofilm-mediated infections. Biofilms are difficult to treat partly due to their tolerance to antibiotics, however the underlying mechanism responsible for this remains unknown. One possible explanation is the presence of persister cells—dormant-like cells that exhibit tolerance to antibiotics. Recent studies have shown a connection between a fumC (fumarase C, a gene in the tricarboxylic acid cycle) knockout strain and increased survival to antibiotics, antimicrobial peptides, and in a Drosophila melanogaster model.ObjectiveIt remained unclear whether a S. aureus high persister strain would have a survival advantage in the presence of innate and adaptive immunity. To further investigate this, a fumC knockout and wild type strains were examined in a murine catheter-associated biofilm model.ResultsInterestingly, mice struggled to clear both S. aureus wild type and the fumC knockout strains. We reasoned both biofilm-mediated infections predominantly consisted of persister cells. To determine the persister cell population within biofilms, expression of a persister cell marker (Pcap5A::dsRED) in a biofilm was examined. Cell sorting of biofilms challenged with antibiotics revealed cells with intermediate and high expression of cap5A had 5.9-and 4.5-fold higher percent survival compared to cells with low cap5A expression. Based on previous findings that persisters are associated with reduced membrane potential, flow cytometry analysis was used to examine the metabolic state of cells within a biofilm. We confirmed cells within biofilms had reduced membrane potential compared to both stationary phase cultures (2.5-fold) and exponential phase cultures (22.4-fold). Supporting these findings, cells within a biofilm still exhibited tolerance to antibiotic challenge following dispersal of the matrix through proteinase K.ConclusionCollectively, these data show that biofilms are largely comprised of persister cells, and this may explain why biofilm infections are often chronic and/or relapsing in clinical settings