Impacts of early vegetation on biogeochemical cycles

<p>Lycophytes (club mosses) represent a distinct lineage of vascular plants with a long history including numerous extant and extinct species. They enriched the soil carbon pool through newly developed root-like structures and promoted soil microbial activity by providing organic matter. They enhanced soil carbon dioxide (CO<sub>2</sub>) via root respiration and also modified soil hydrology. These effects had the potential to promote the dissolution of silicate minerals, thus intensifying silicate weathering. The weathering of silicate rocks is considered one of the most significant geo-chemical regulators of atmospheric CO<sub>2</sub> on a long (hundreds of thousands to millions of years) timescale. The motivation for this study is to achieve an increased understanding of the realized impacts of lycophytes on silicate weathering and past climate. To this end, it is necessary to quantify physiological characteristics, spatial distribution, the carbon balance, and hydrological impacts of early lycophytes. These properties, however, cannot be easily derived from proxies. Hence, as a first step, a process-based model is developed here to estimate net carbon uptake by these organisms at the local scale, considering key features such as root distribution, stomatal regulation of water loss, and root respiration.<br>The model features ranges of key physiological traits of lycophytes to predict the emerging characteristics of the lycophyte community under any given climate by implicitly simulating the process of selection. In this way, also extinct plant communities can be represented.<br>In addition to physiological properties, the model also simulates weathering rates using a simple limit-based approach and estimates the biotic enhancement of weathering by lycophytes. We run the Lycophyte model, called LYCOm, at seven sites encompassing various climate zones under today's climatic conditions. LYCOm is able to simulate realistic properties of lycophyte communities at the respective locations and estimates an average NPP ranging from 245 g carbon m<sup>-2</sup> year<sup>-1</sup> in Costa Rica to 126 g carbon m<sup>-2</sup> year<sup>-1</sup> in Estonia. Our limit-based weathering model predicts a chemical weathering rate ranging from 0.026 to 0.31 mm rock a<sup>-1 </sup>, thereby highlighting the potential importance of lycophytes at the local scale for enhancing chemical weathering. Our modeling study establishes a basis for assessing biotic enhancement of weathering by lycophytes at the global scale and also for the geological past. </p>

Swarm robotics:design and implementation

This project presents a swarming and herding behaviour using simple robots. The main goal is to demonstrate the applicability of artificial intelligence (AI) in simple robotics that can then be scaled to industrial and consumer markets to further the ability of automation. AI can be achieved in many different ways; this paper explores the possible platforms on which to build a simple AI robots from consumer grade microcontrollers. Emphasis on simplicity is the main focus of this paper. Cheap and 8 bit microcontrollers were used as the brain of each robot in a decentralized swarm environment were each robot is autonomous but still a part of the whole. These simple robots don’t communicate directly with each other. They will utilize simple IR sensors to sense each other and simple limit switches to sense other obstacles in their environment. Their main objective is to assemble at certain location after initial start from random locations, and after converging they would move as a single unit without collisions. Using readily available microcontrollers and simple circuit design, semiconsistent swarming behaviour was achieved. These robots don’t follow a set path but will react dynamically to different scenarios, guided by their simple AI algorithm.

Airgap and Wave in Deck Impact Statistics

As offshore reservoirs are depleted, the seabed may subside. Bottom fixed installations which have previously had sufficient clearance between the deck and the sea surface may be in a situation where wave impact with the deck must be considered at relevant probability levels. Some statistical aspects associated with the calculation of a deck impact load with a prescribed probability of occurrence are the subject of the present paper. The Short Crest JIP addressed the distribution of the crest height in extreme sea states, the properties of the largest crests and the deck impact loading on a closed deck. It was concluded that the largest waves in the sea may be in the process of breaking and thus have properties which deviate significantly from estimates found from weakly nonlinear irregular or regular wave theory. The present paper addresses findings from the Short Crest JIP regarding • long-term analysis of wave heights and crest, including the effect of wave breaking • air gap analysis for jacket, TLP and semisubmersible using 2nd order time domain simulations over the platform area • statistics for horizontal wave-in-deck impacts for short crested sea versus for long crested sea • structural reliability analysis of jackets for some simple limit states that are governed by loads caused by impact of extreme crests

Connecting mirror symmetry in 3D and 2D via localization

We explicitly apply localization results to study the interpolation between three- and two-dimensional mirror symmetries for Abelian gauge theories with four supercharges. We first use the ellipsoid [Formula: see text] partition functions to verify the mirror symmetry between a pair of general three-dimensional 𝒩 = 2 Abelian Chern–Simons quiver gauge theories. These expressions readily factorize into holomorphic blocks and their antiholomorphic copies, so we can also obtain the partition functions on S1×S2 via fusion procedure. We then demonstrate S1×S2 partition functions for the three-dimensional Abelian gauge theories can be dimensionally reduced to the S2 partition functions of 𝒩 = (2, 2) GLSM and Landau–Ginzburg model for the corresponding two-dimensional mirror pair, as anticipated previously in M. Aganagic et al., J. High Energy Phys.0107, 022 (2001). We also comment on the analogous interpolation for the non-Abelian gauge theories and compute the K-theory vortex partition function for a simple limit to verify the prediction from holomorphic block.

Globally stable control of a dynamic bipedal walker using adaptive frequency oscillators

SUMMARYWe present a control method for a simple limit-cycle bipedal walker that uses adaptive frequency oscillators (AFOs) to generate stable gaits. Existence of stable limit cycles is demonstrated with an inverted-pendulum model. This model predicts a proportional relationship between hip torque amplitude and stride frequency. The closed-loop walking control incorporates adaptive Fourier analysis to generate a uniform oscillator phase. Gait solutions (fixed points) are predicted via linearization of the walker model, and employed as initial conditions to generate exact solutions via simulation. Global stability is determined via a recursive algorithm that generates the approximate basin of attraction of a fixed point. We also present an initial study on the implementation of AFO-based control on a bipedal walker with realistic mass distribution and articulated knee joints.

Excimer Laser Micromachining Using Binary Mask Projection for Large Area Patterning With Single Micrometer Features

Excimer laser micromachining using binary mask projection has been investigated for rapid patterning of single micrometer features over large areas of various substrates. Simple limit for depth of focus that determines the depth to width aspect ratios is given and verified for different materials. Binary mask projection technique is found to conformally reproduce the mask features from the millimetre to the micrometer scale under proper focusing conditions. Large arrays of 1 μm and 15 μm holes on Kapton are made with high resolution and uniform periodicity. Material removal rate (MRR) for the laser machining of these holes are examined and the machining efficiency for these are found to have different dependence on the fluence. A saturation of hole-depth with increasing number of pulses is obtained.