42,806 research outputs found
Serratia marcescens, the âFlameâ Strain: The Genesis of a New Variant A Newly Described Strain with Prolific Pigment Produced at High Temperature
Serratia marcescens, a Gram-negative, rod-shaped, facultative anaerobe (Fig. 1), is ubiquitous in water, soil, and natural settings. It is easily grown in the lab and may serve as an ideal model for adaptation studies because of the natural color variation of S. marcescens (Gillen 2008). In this paper, we describe a new variant with prolific pigment (prodigiosin) production at high temperatures. In the wild and in buildings, S. marcescens is noted for the production of a bright red pigment called prodigiosin (Williams 1973). We have found a new strain that appears to have adapted to a relatively new pond system called Liberty Library Lake. It produces pigment up to 40°C without any enrichment to media. Most wild-type strains, like NIMA, produce pigment normally up to 30°C, but with extensive enrichment, wild-type strains can produce pigment up to 40°C. This new strain, called the âFlameâ strain, not only produces prodigiosin to 39â40°C but also in higher abundance at 35°C and at a brighter hue. NIMA strains can produce pigment at 39â40°C with Serratia Synergy Agar (glycerol, peptone, agar) but not on TSA nor any common agar. It takes significant enhancement for any other Serratia marcescens strains to produce pigment even at 35°C.
The Flame strainâs brief appearance in a local, small lake appears to be a phenotypic diversification and adaptation to an environmental perturbation this past school year. The environmental stress prior to its appearance was an autumn drought. Eventually, heavy rainfall occurred and the new strain was discovered. Its appearance coincided with an unusually high abundance of coliforms, avian Giardia, and Cryptosporidium, along with chemical treatment of the lake. The unusual conditions seem to favor a rapid phenotypic diversification and adaptation. The new strain still retains the pigment production at nearly 10°C higher for ânormalâ prodigiosin production by wild-type Serratia marcescens. This genesis of this new strain seems to have occurred as special conditions favored this new variant. It may be closer to a âproto-typeâ (ancestral) strain than to more common wild-type strains, like NIMA and BS303. It appears that most wild-type strains, like NIMA and BS303, may have lost this information over time since added enrichment is necessary to produce pigment at 39â40°C. The unusual conditions may have selected for this newly adapted strain to be common for a short time. Also as conditions returned to ânormal,â a common wild-type strain reappeared at the local lake, and the Flame strain was no longer found.
The objective of this article is to explain the mysterious origin of a new strain of Serratia marcescens that produces prodigiosin up to 40°C without any enrichment to media. This strain can naturally produce prolific pigment that is a bright, flame-red. Since Serratia marcescens offers protection from other microbes, UV light, and drought, it is a wonderful example of intelligent design commonly seen in the microbial world
Learning in Economics: Where Do We Stand?
This paper briefly reviews the current literature on learning in economics from a behavioral point of view. It critically compares theory with aspects of learning in real-life and with evidence from laboratory experiments, and argues that most customary approaches lack criteria for their applicability. Hence, there is a need for a theory that includes criteria when to employ which theory or which element(s) of existing theories contingent on the situation or environment in question. A discussion of several unsolved issues in economic learning stresses the fundamental role of learning conditions that have be neglected in the literature, but are accounted for in behavioral approaches such as "contingent learning".economic learning, behavioral economics, experiments, game theory, information feedback, contingent learning
Issues in cross-cultural studies of advertising audiovisual material
This article presents an approach to cross-cultural studies of advertising audiovisual material that departs from the typical rigid marketing models. It favours a more qualitative inductive approach to corpuses, in which audiovisual texts are not approached or compared through the use of standardised American tools. After reviewing the usual marketing tools, the article focuses on the steps researchers can usefully take, from the gathering of audiovisual texts from two different environments to their classification, two important steps that are critical in such studies
Generative Design in Minecraft (GDMC), Settlement Generation Competition
This paper introduces the settlement generation competition for Minecraft,
the first part of the Generative Design in Minecraft challenge. The settlement
generation competition is about creating Artificial Intelligence (AI) agents
that can produce functional, aesthetically appealing and believable settlements
adapted to a given Minecraft map - ideally at a level that can compete with
human created designs. The aim of the competition is to advance procedural
content generation for games, especially in overcoming the challenges of
adaptive and holistic PCG. The paper introduces the technical details of the
challenge, but mostly focuses on what challenges this competition provides and
why they are scientifically relevant.Comment: 10 pages, 5 figures, Part of the Foundations of Digital Games 2018
proceedings, as part of the workshop on Procedural Content Generatio
An invitation to grieve: reconsidering critical incident responses by support teams in the school setting
This paper proposes that consideration could be given to an invitational intervention rather than an expectational intervention when support personnel respond to a critical incident in schools. Intuitively many practitioners know that it is necessary for guidance/counselling personnel to intervene in schools in and following times of trauma. Most educational authorities in Australia have mandated the formulation of a critical incident intervention plan. This paper defines the term critical incident and then outlines current intervention processes, discussing the efficacy of debriefing interventions. Recent literature suggests that even though it is accepted that a planned intervention is necessary, there is scant evidence as to the effectiveness of debriefing interventions in stemming later symptoms of post traumatic stress disorder. The authors of this paper advocate for an expressive therapy intervention that is invitational rather than expectational, arguing that not all people respond to trauma in the same way and to expect that they will need to recall and retell what has happened is most likely a dangerous assumption. A model of invitation using Howard Gardnerâs (1983) multiple intelligences is proposed so that students are invited to grieve and understand emotionally what is happening to them following a critical incident
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