Biology and potential biogeochemical impacts of novel predatory flavobacteria

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2010Predatory bacteria are ubiquitous in aquatic environments and may be important players in the ecology and biogeochemistry of microbial communities. Three novel strains belonging to two genera of marine flavobacteria, Olleya and Tenacibaculum, were cultured from coastal sediments and found to be predatory on other bacteria on surfaces. Two published species of the genus Tenacibaculum were also observed to grow by lysis of prey bacteria, raising the possibility that predation may be a widespread lifestyle amongst marine flavobacteria, which are diverse and abundant in a variety of marine environments. The marine flavobacterial clade is known to include species capable of photoheterotrophy, scavenging of polymeric organic substances, pathogenesis on animals, the degradation and lysis of phytoplankton blooms and, now, predation on bacterial communities. Strains from the two genera were found to exhibit divergent prey specificities and growth yields when growing predatorily. Olleya sp. predatory cells accumulated to an order of magnitude greater cell densities than Tenacibaculum sp. cells on equivalent prey cell densities. Experiments were conducted to constrain the potential of the novel isolates to affect prey communities under more environmentally relevant conditions. An investigation of the minimum number of predatory cells needed to generate clearings of prey cells found that the inoculation of individual predatory flavobacteria cells can ultimately result in dense lytic swarms. In some cases, the susceptibility of particular prey species to lysis by a flavobacterial predator was found to vary based on the growth state of the prey cells or the presence of their spent growth media. A novel methodology for the experimental study of biofilms was used to assess the impact of exposure to predatory marine flavobacteria on the release of macronutrients from prey biofilms. The Olleya sp. predator had a stimulative effect on macronutrient release while the Tenacibaculum sp. did not, further suggesting the two groups of predators are adapted to different ecological niches.Support by the National Science Foundation (NSF) Division of Molecular and Cellular Biosciences Grant (MCB- 0348425), the MIT Student Assistance Fund, the Woods Hole Oceanographic Institution (WHOI) Academic Programs Office, WHOI Coastal Ocean Institute (COI) and WHOI Ocean Venture Fund grant, COI and the WHOI Ocean Life Institute

Aldo van Eyck's Playgrounds:Aesthetics, Affordances, and Creativity

After World War II, the Dutch architect Aldo van Eyck developed hundreds of playgrounds in the city of Amsterdam. These public playgrounds were located in parks, squares, and derelict sites, and consisted of minimalistic aesthetic play equipment that was supposed to stimulate the creativity of children. Over the last decades, these playgrounds have been studied by sociologists, theorists of art and architecture, and psychologists. Adopting an ecological approach to the human environment, it is argued that the abstract forms of van Eyck’s play sculptures indeed stimulate the creativity of the child. Whereas a slide or a swing almost dictates what a child is supposed to do, van Eyck’s play equipment invites the child to actively explore the numerous affordances (action possibilities) it provided. However, it is argued that the standardization (e.g., equal distances between blocks or bars) that tends to characterize van Eyck’ play equipment has negative effects on the playability. This standardization, which was arguably the result of the aesthetic motives of the designer, might be appealing to children when simply looking at the equipment, but it is not of overriding importance to them when playing in it. Indeed, a recent study indicates that the affordances provided by messy structures appear to have a greater appeal to playing children

Height, Size, and/or Gap Width Variation in Jumping Stone Configurations:Which Form of Variation Attracts Children the Most?

Earlier studies revealed that children prefer nonstandardized jumping stone configurations to standardized ones. In the present study, we examined whether children playing on jumping stones prefer variation in stone height, stone size, and/or gap width. In Experiment 1, children could play freely on one standardized configuration and three configurations in which one of the aforementioned factors was varied. It was found that children judged the variation in height as most fun. Yet, the configuration with gap width variation appeared to be most challenging for the children-most overground steps were made in this configuration. In Experiment 2, we examined whether the attractiveness of the configurations increased when height variation was combined with the other forms of variation. Adding size and/or gap width variation to the variation in height did not contribute to the attractiveness of the configuration. In line with experiment 1, it was found that the configurations with gap width variation were judged as the most challenging for children. The implications of these results are discussed in the context of the literature on play.</p

Inciting protocols

This paper studies patenting decisions by firms in relation to the negotiation and signing of the Helsinki and Oslo protocol as part of the Convention on Long-Range Transboundary Air Pollution. We use a uniquely constructed patent data set on SO 2 abatement technologies filed in 15 signatory and non-signatory countries in the period 1970-1997. The data distinguish between so-called 'mother' patents, or original inventions, and 'family' patents, which represent the same invention but are patents filed in foreign countries. Our analysis suggests that not only local environmental regulations matter for patenting decisions. International environmental agreements provide incentives for additional inventive activity in and the diffusion of knowledge towards signatory countries by reducing investment uncertainty for inventing firms

'The End of Sitting':An Empirical Study on Working in an Office of the Future

Background Inspired by recent findings that prolonged sitting has detrimental health effects, Rietveld Architecture Art Affordances (RAAAF) and visual artist Barbara Visser designed a working environment without chairs and desks. This environment, which they called The End of Sitting, is a sculpture whose surfaces afford working in several non-sitting postures (e.g. lying, standing, leaning). Objective In the present study, it was tested how people use and experience The End of Sitting. Eighteen participants were to work in this environment and in a conventional office with chairs and desks, and the participants' activities, postures, and locations in each working environment were monitored. In addition, participants' experiences with working in the offices were measured with a questionnaire. Results It was found that 83 % of participants worked in more than one non-sitting posture in The End of Sitting. All these participants also changed location in this working environment. On the other hand, in the conventional office all but one participant sat on a chair at a desk during the entire work session. On average, participants reported that The End of Sitting supported their well-being more than the conventional office. Participants also felt more energetic after working in The End of Sitting. No differences between the working environments were found in reported concentration levels and satisfaction with the created product. Conclusion The End of Sitting is a potential alternative working environment that deserves to be examined in more detail

The degree to which traditional play equipment, Parkour play elements, and Aldo van Eyck's play sculptures have an open function

The concept of open functions was introduced to capture an intended feature of van Eyck's seminal play sculptures - they do not suggest a specific action. In a recent study, Van der Schaaf, A. L., S. R. Caljouw, and R. Withagen. (2020. "Are Children Attracted to Play Elements with an Open Function?" Ecological Psychology 32: 79-94) aimed to determine the degree of openness of Parkour play elements by asking participants what behavior children will mainly perform on them. In the present study, we used this method to determine the degree of openness of traditional play elements (e.g. a slide), van Eyck's play sculptures, and Parkour play elements. In addition, we measured the time participants needed to answer the question of what action children will mainly perform on the different elements. We found that generally the Parkour elements have the highest degree of openness. Interestingly, van Eyck's play elements appeared not to be that open. Moreover, the reaction time proved to be an alternative measure for the degree of openness

Crossing the Gap:Older Adults Do Not Create Less Challenging Stepping Stone Configurations Than Young Adults

Background Despite the known health benefits of physical activity, the number of older adults exercising regularly remains low in many countries. There is a demand for public open space interventions that can safely train balance, muscular strength, and cardiovascular fitness. In this participatory design study, older adults and young adults were to create their own stepping stones configurations. We provided them with six stepping stones, and examined the gap widths that each group of participants created and how they used the configurations. Results The created absolute gap distances by the older adults were smaller than those of the younger adults. Yet, the amount of challenge (in terms of the created gap widths relative to a person's estimated stepping capability) did not significantly differ between the young and older adults. Furthermore, both groups created non-standardized stepping stone configurations in which the number of different gap widths did not significantly differ between the young and older adults. Interestingly, while using their personalized design, older adults made significantly more gap crossings than younger adults over a given timespan. This finding tentatively suggests that personalized design invites physical activity in older adults. Conclusion The present study demonstrated that older adults are not more conservative in designing their own stepping stone configuration than young adults. Especially in light of the public health concern to increase physical activity in seniors, this is a promising outcome. However, field tests are needed to establish whether the older adults' stepping stones designs also invite physical activity in their daily environment

Gap-crossing behavior in a standardized and a nonstandardized jumping stone configuration

Over the last years, the omnipresent standardization of playgrounds-the distances between, for example, jumping stones tend to be equal-has been criticized by both scientists and architects. First, it has been argued that standardization fails to do justice to the variability in the children's action capabilities. Second, it might simplify play in that children repetitively cross over the same distance and, thus, do not have to worry about their movements anymore. In the present study we examined the gap-crossing behavior of children in both a standardized and a nonstandardized jumping stone configuration. Children, between 5 and 10 years of age, were to play in each configuration for two minutes. No significant differences between the configurations were found in the number of gaps the children crossed and the percentage of jumps (ps>0.05). However, more children crossed a gap that they perceived as challenging (i.e. gap width close to their estimated maximum jumping distance) in the nonstandardized configuration than in the standardized one. Interestingly, significant differences were found in variables reflecting the children's action preparation-the variation in both the time on a jumping stone and the numbers of steps on it was bigger in the nonstandardized playground than in the standardized one (ps<0.05). The implications of these findings are discussed for both the design of playgrounds and the academic discussions about them

Aging affects attunement in perceiving length by dynamic touch

Earlier studies have revealed age-dependent differences in perception by dynamic touch. In the present study, we examined whether the capacity to learn deteriorates with aging. Adopting an ecological approach to learning, the authors examined the process of attunement—that is, the changes in what informational variable is exploited. Young and elderly adults were trained to perceive the lengths of unseen, handheld rods. It was found that the capacity to attune declines with aging: Contrary to the young adults, the elderly proved unsuccessful in learning to detect the specifying informational variables. The fact that aging affects the capacity to attune sets a new line of research in the study of perception and perceptual-motor skills of elderly. The authors discuss the implications of their findings for the ongoing discussions on the ecological approach to learning

No transfer of calibration between action and perception in learning a golf putting task

We assessed calibration of perception and action in the context of a golf putting task. Previous research has shown that right-handed novice golfers make rightward errors both in the perception of the perfect aiming line from the ball to the hole and in the putting action. Right-handed experts, however, produce accurate putting actions but tend to make leftward errors in perception. In two experiments, we examined whether these skill-related differences in directional error reflect transfer of calibration from action to perception. In the main experiment, three groups of right-handed novice participants followed a pretest, practice, posttest, retention test design. During the tests, directional error for the putting action and the perception of the perfect aiming line were determined. During practice, participants were provided only with verbal outcome feedback about directional error; one group trained perception and the second trained action, whereas the third group did not practice. Practice led to a relatively permanent annihilation of directional error, but these improvements in accuracy were specific to the trained task. Hence, no transfer of calibration occurred between perception and action. The findings are discussed within the two-visual-system model for perception and action, and implications for perceptual learning in action are raised