Bulletin of the American Physical Society
APS March Meeting 2017
Volume 62, Number 4
Monday–Friday, March 13–17, 2017; New Orleans, Louisiana
Session Y49: Environment-energy Nexus – a Physics PerspectiveInvited Undergraduate
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Sponsoring Units: DBIO GERA Chair: Marek Cieplak, Institute of Physics, Polish Academy of Sciences Room: 396 |
Friday, March 17, 2017 11:15AM - 11:51AM |
Y49.00001: Metabolic scaling and biodiversity of forests Invited Speaker: Jayanth Banavar Forests are biologically diverse and play a critical role in the dynamics of earth-climate systems. A forest is a tremendously complex system comprising co-existing rooted trees of many species and many sizes and utilizing resources from the environment. The trees interact with each other and with their environment and the interactions are not precisely known. Using scaling ideas, we will present a theoretical framework for understanding the role of geometry in determining the metabolic rate of a tree and of a forest. The quantification of tropical tree biodiversity and their abundances is still an open and challenging problem. Using a global-scale compilation, we will present a method that allows one to predict, from local censuses, the biodiversity and patterns of species abundance at the whole forest scale. The method allows one to quantify the minimum percentage cover of the forest that should be sampled in order to have a precise prediction of the estimates of biodiversity and species abundances. [Preview Abstract] |
Friday, March 17, 2017 11:51AM - 12:27PM |
Y49.00002: Conversion of biomass to biofuels by bacterial cellulosomes$^{\mathrm{1}}$ Invited Speaker: Damien Thompson Lignocellulosic biomass waste has the potential to be converted to biofuels and other value-added chemicals in a renewable manner. However, a cost-effective depolymerization of polysaccharides is challenging technologically. In order to take on the challenge, one can use cocktails of bacterial or fungal enzymes, known as cellulases. Another promising approach, discussed here, is to employ certain bacteria, such as Clostridum thermocellum, that grow extracellular molecular complexes known as cellulosomes. A cellulosome mounts many different cellulases on a nonhydrolytic structural unit consisting of a number of the cohesin domains. The domains bind to their complementary dockerin domains belonging to the catalytic subunits. In this lecture, I will highlight results of the experimental and theoretical research on cellulosomes performed by the European consortium CellulosomePlus$^{\mathrm{1}}$ (Cajal Institute in Madrid, Weizmann Institute in Rehovot, Ludwig Maximillian's University in Munich, Institute of Physics in Warsaw, Oceanography Institute in Roscoff, University of Limerick and three industrial partners). The goals of the consortium include characterization and understanding the structure and function of several cellulosomes as well as the development of designer cellulosomes that would be more effective than their wild type versions. The subjects covered in the lecture include the role of the linkers on the properties of cellulases, effects of singlesite mutations on the mechanical and thermodynamic stabilities of cohesin c7A in the cellulosome of C. thermocellum, the non-local impact of such mutations, the mechanics of the cohesin-dockerin interface, protein-hexaose and protein-cellulose interactions, and the status of the implementation efforts. $^{\mathrm{1}}$The European Framework Programme VII NMP grant 604530-2 (CellulosomePlus) [Preview Abstract] |
Friday, March 17, 2017 12:27PM - 1:03PM |
Y49.00003: Growing swimming algae for bioenergy Invited Speaker: Ottavio Croze Biofuel production from photosynthetic microalgae is not commercially viable due to high processing costs. New engineering and biological solutions are being sought to reduce these costs by increasing processing efficiency (productivity per energy input). Important physics, however, is ignored. For example, the fluid dynamics of algal suspensions in photobioreactors (ponds or tube arrays) is non-trivial, particularly if the algae swim. Cell reorientation by passive viscous and gravitational torques (gyrotaxis) or active reorientation by light (phototaxis) cause swimming algae in suspension to structure in flows, even turbulent ones. This impacts the distribution and dispersion of swimmers, with significant consequences for photobioreactor operation and design. In this talk, I will describe a theory that predicts swimmer dispersion in laminar pipe flows. I will then then present experimental tests of the theory, as well as new results on the circadian suspension dynamics of the alga\textit{ Chlamydomonas reinhardtii} in lab-scale photobioreactors. Finally, I will briefly consider the implications of our work, and related active matter research, for improving algal bioprocessing efficiency. [Preview Abstract] |
Friday, March 17, 2017 1:03PM - 1:39PM |
Y49.00004: Cell wall science for a sustainable future Invited Speaker: Janna Maranas |
Friday, March 17, 2017 1:39PM - 2:15PM |
Y49.00005: Inferring biodiversity maintenance mechanisms from ecological pattern Invited Speaker: Annette Ostling Among a set of competitors for a single common resource, the best will simply exclude the others. Yet in nature we can see astounding diversity of competing species. Do close similarities in species' response to the local environment primarily explain their coexistence? Or is this diversity possible because of differences between species that stabilize their coexistence? And if so, what particular differences between species are important in particular communities? Some ecological communities lend themselves to experimental manipulation to begin to answer these questions. Yet for many other communities, such as tree species in forests, the logistical hurdles to this approach are daunting. Faster progress could be made in ecology if insight into biodiversity maintenance mechanisms could be gained from patterns exhibited in local ecological communities, such as how coexisting species are distributed in their ecological traits and relative abundance. Hurdles that we need to overcome to be able to gain such insight include: 1) further developing neutral theory, a quantitative process-based null model of community pattern resulting when species similarities are what allow their coexistence, and 2) better understanding what patterns to expect when species differences dominate instead, particularly in the context of stochasticity and immigration. I will describe our ongoing research to overcome these hurdles, to provide better tools for analyzing observed pattern. [Preview Abstract] |
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