Effects of temporal variability of disturbance on the succession in marine fouling communities in northern-central Chile

We investigated the effects of temporal variability in a disturbance regime on fouling communities at two study sites in a northern-central Chilean bay. Fouling assemblages grown on artificial settlement substrata were disturbed by mechanical removal of biomass at different time intervals. Using one single disturbance frequency (10 disturbance events over 5 months) we applied 7 different temporal disturbance treatments: a constant disturbance regime (identical intervals between disturbance events), and 6 variable treatments where both variableness and sequences of intervals between disturbance events were manipulated. Two levels of temporal variableness (low and high, i.e. disturbance events were either dispersed or highly clumped in time) in the disturbance regime were applied by modifying the time intervals between subsequent disturbance events. To investigate the temporal coupling between disturbance events and other ecological processes (e.g. larval supply and recruitment intensity), three different sequences of disturbance intervals were nested in each of the two levels of temporal variableness. Species richness, evenness, total abundance, and structure of communities that experienced the various disturbance regimes were compared at the end of the experiment (15 days after the last disturbance event). Disturbance strongly influenced the community structure and led to a decrease in evenness and total abundance but not species richness. In undisturbed reference communities, the dominant competitor Pyura chilensis (Tunicata) occupied most available space while this species was suppressed in all disturbed treatments. Surprisingly, neither temporal variableness in the disturbance regime nor the sequence of intervals between disturbance events had an effect on community structure. Temporal variability in high disturbance regimes may be of minor importance for fouling communities, because they are dominated by opportunistic species that are adapted to rapidly exploit available space

Space applications of Automation, Robotics And Machine Intelligence Systems (ARAMIS). Volume 3, phase 2: Executive summary

The field of telepresence is defined, and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA's plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies are included. Several space projects are examined in detail to determine what capabilities are required of a telepresence system in order to accomplish various tasks, such as servicing and assembly. The key operational and technological areas are identified, conclusions and recommendations are made for further research, and an example developmental program leading to an operational telepresence servicer is presented

Space Applications of Automation, Robotics and Machine Intelligence Systems (ARAMIS), phase 2. Volume 1: Telepresence technology base development

The field of telepresence is defined, and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA's plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies over the next decade are included. Several space projects are examined in detail to determine what capabilities are required of a telepresence system in order to accomplish various tasks, such as servicing and assembly. The key operational and technological areas are identified, conclusions and recommendations are made for further research, and an example developmental program is presented, leading to an operational telepresence servicer

Space Applications of Automation, Robotics and Machine Intelligence Systems (ARAMIS), phase 2. Volume 2: Telepresence project applications

The field of telepresence is defined and overviews of those capabilities that are now available, and those that will be required to support a NASA telepresence effort are provided. Investigation of NASA' plans and goals with regard to telepresence, extensive literature search for materials relating to relevant technologies, a description of these technologies and their state of the art, and projections for advances in these technologies over the next decade are included

Long-term predictability of mean daily temperature data

International audienceWe quantify the long-term predictability of global mean daily temperature data by means of the Rényi entropy of second order K2. We are interested in the yearly amplitude fluctuations of the temperature. Hence, the data are low-pass filtered. The obtained oscillatory signal has a more or less constant frequency, depending on the geographical coordinates, but its amplitude fluctuates irregularly. Our estimate of K2 quantifies the complexity of these amplitude fluctuations. We compare the results obtained for the CRU data set (interpolated measured temperature in the years 1901-2003 with 0.5° resolution, Mitchell et al., 2005)with the ones obtained for the temperature data from a coupled ocean-atmosphere global circulation model (AOGCM, calculated at DKRZ). Furthermore, we compare the results obtained by means of K2 with the linear variance of the temperature data

Dynamic contour tonometry versus Goldmann applanation tonometry: challenging the gold standard

The accurate measurement of intraocular pressure (IOP) is fundamental to almost any ophthalmic examination. Dynamic contour tonometry (DCT) was introduced 5 years ago as an entirely novel contact tonometry principle designed to measure IOP largely independently of corneal properties. Since then, many studies have compared the performance of this tonometer to the Goldmann applanation tonometer (GAT) and other tonometers in healthy eyes, as well as eyes with glaucoma or corneal diseases, and after corneal surgery. There is now strong evidence that DCT measures IOP very accurately, with very low inter- and intraobserver variability. This article summarizes the findings of these studies and analyzes the role of DCT in challenging GAT as the gold-standard tonometer for IOP measurements

Is Category Expansion a Realistic Long-Term Objective for Established Brands?

How often do established CPG categories expand following a period of stationarity? To what extent can the levers under manufacturer control bring about persistent growth in total category value? The authors explore these questions in order to test the commonly held assertion that brand leaders in established markets can grow sales by expanding total category demand. Findings from a study of US household panel data describing the purchasing of nearly 500 small and large categories by 60,000 households over a nine-year period are presented. The observations focus on the growth impact of three sales levers, category penetration, purchase volume per buyer, and price per volume paid, in various strategic windows ranging from one to nine years. The results demonstrate that category penetration increase is the most likely lever for category growth. The association between over-time revenue increase and growth in buying household numbers is far stronger than that between unit price increases or category usage. While this clearly indicates a promising strategic direction for brand management, results also carry a health warning: categories are relatively volatile in the short term, but highly stable over time, therefore while the direction is clear the path is very narrow indeed