Fuels and fires influence vegetation via above- and below-ground pathways in a high-diversity plant community

1. Fire strongly influences plant populations and communities around the world, making it an important agent of plant evolution. Fire influences vegetation through multiple pathways, both above- and belowground. Few studies have yet attempted to tie these pathways together in a mechanistic way through soil heating even though the importance of soil heating for plants in fire-prone ecosystems is increasingly recognized. 2. Here we combine an experimental approach with structural equation modelling (SEM) to simultaneously examine multiple pathways through which fire might influence herbaceous vegetation. In a high-diversity longleaf pine groundcover community in Louisiana, USA, we manipulated fine-fuel biomass and monitored the resulting fires with high-resolution thermocouples placed in vertical profile above- and belowground. 3. We predicted that vegetation response to burning would be inversely related to fuel load owing to relationships among fuels, fire temperature, duration and soil heating. 4. We found that fuel manipulations altered fire properties and vegetation responses, of which soil heating proved to be a highly accurate predictor. Fire duration acting through soil heating was important for vegetation response in our SEMs, whereas fire temperature was not. 5. Our results indicate that in this herbaceous plant community, fire duration is a good predictor of soil heating and therefore of vegetation response to fire. Soil heating may be the key determinant of vegetation response to fire in ecosystems wherein plants persist by resprouting or reseeding from soil-stored propagules. 6. Synthesis. Our SEMs demonstrate how the complex pathways through which fires influence plant community structure and dynamics can be examined simultaneously. Comparative studies of these pathways across different communities will provide important insights into the ecology, evolution and conservation of fire-prone ecosystems

Feature Improvement and Cost Reduction of Baitcasting Fishing Reels for Emerging Markets

Baitcasting fishing reels are a challenging product to sell to new users in emerging markets. Their complex and less-than-intuitive design make them poor candidates for a novice fisherman selecting his or her first fishing reel. Based upon manufacturer constraints and design requirements, our team lowered the price point and improved the usability of the Okuma Cerros baitcasting fishing reel to make it more appealing to a wider range of consumers, especially in emerging markets. This project resulted in a three-phase redesign: reducing cost via alternative materials and replacing bearings with bushings; prototyping a simplified cast control system; and proposing an improved user interface

A novel cardioport for beating-heart, image-guided intracardiac surgery

Objective Intracardiac beating-heart procedures require the introduction and exchange of complex instruments and devices. To prevent potential complications such as air embolism and bleeding, a universal cardioport was designed and tested. Methods The design consists of a port body and a series of interchangeable sleeves. The port uses a fluid purging system to remove air from the instrument before insertion into the heart, and a valve system minimizes blood loss during instrument changes. Results The cardioport was tested ex vivo and in vivo in pigs (n = 5). Beating-heart procedures, such as septal defect closure and mitral valve repair, were modeled. Ex vivo trials (n = 150) were performed, and no air emboli were introduced using the port. In comparison, air emboli were detected in 40% to 85% of the cases without the use of the port-based purging system. Port operation revealed excellent ergonomics and minimal blood loss. Conclusions A novel cardioport system designed to prevent air entry and blood loss from transcardiac instrument introduction was shown to be an enabling platform for intracardiac beating-heart surgery. The port system improves safety and facilitates further development of complex instruments and devices for transcardiac beating-heart surgery.Center for Integration of Medicine and Innovative Technology (Award 07-026)National Institutes of Health (U.S.) (National Heart, Lung, and Blood Institute Award 5R01HL073647)Massachusetts Technology Transfer Cente

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Morphological Processing In the Nabu System

The Nabu morphological proc'essor is designed to perform a number of different functions, of which five have so far been identified: analysis, guessing (about unknown words), syn- thesis, defaulting (proposing the most likely infiectional paradigm for a new base form), and coding (producing all possible inflectional paradigm variants for a new base form). Complete or very substantial analyzers have been produced for a number of diverse languages; other functions have been implemented as well. This paper discusses our design philosophy, as well as our technique and its implementation

The design of a power system using treated aluminum fuel

Thesis: S.M., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.Cataloged from PDF version of thesis.Includes bibliographical references (pages 85-87).Aluminum is the most abundant metal in the Earth's crust and a highly sought after fuel source due to its extreme energy density. It has the ability to produce large quantities of hydrogen and heat when reacted with water making it an attractive fuel for underwater vehicles and ocean sensor platforms. The biggest challenge in using aluminum as a fuel has been overcoming the rapidly-forming oxide layer that gives aluminum its excellent corrosion resistance. Recently, a safe, controllable, and inexpensive treatment process was developed which bypasses this layer and allows aluminum to efficiently react with water. The fuel made using this process generates an average hydrogen yield of 94 percent. This fuel has been successfully tested in a power system, in which a fuel cell generated 30 watts for 90 minutes using only hydrogen. Firstly, an introduction and background is given on the benefits and challenges of using hydrogen as a fuel. The basic chemistry and background behind using aluminum as a fuel provides the motivation behind this thesis. Secondly, the materials science of using aluminum fuels is examined as well as prior aluminum fuels which have been attempted. The treatment process is then analyzed using the physics previously discussed as well as the overall efficiency and practicality of the treated aluminum fuel. Thirdly, a working power system design is then presented which runs entirely off hydrogen gas generated by specially treated aluminum fuel. This system was run for 90 minutes at 30 watts, showing that aluminum can be used as a safe and environmentally friendly fuel source.by Jonathan Slocum.S.M

Design and modeling of a force sensitive toothbrush by using a buckling truss structure

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2014.Cataloged from PDF version of thesis.Includes bibliographical references (page 39).Excessive force applied to teeth with a toothbrush during brushing may cause tooth erosion and gum recession. There have been many attempts by others to mitigate this effect with a force-sensitive toothbrush that can alert a user when excessive force is applied. However, many of the prior art solutions to this problem do not have a tactile response to alert the user when excessive force is applied. Further many prior art solutions are often bulky, have multiple components, and/or are not aesthetically pleasing or ergonomic. Some prior art buckling structures also often had thin hinge sections which are difficult to injection mold and act as failure points and the resulting broken structure can be dangerous. Prior art buckling toothbrush structures further had the problem of once they buckled, the structure was so substantially weakened, that continued application of force could cause the structure to plastically fail. A force-sensitive toothbrush incorporates a bistable truss into the neck of the toothbrush. The mechanism can alert a user to excessive brushing force by changing shape in response to brushing forces exceeding a predetermined threshold. The mechanism can also automatically return to its original state when the brushing forces are lowered back down below the predetermined level. The mechanism may include a force-sensitive region having an upper beam and a lower beam joined together to form a triangular truss, both grounded to the handle. This mechanism can advantageously be molded into an integral toothbrush body using an injection molding operation.by Jonathan Slocum.S.B

A BUCKLING FLEXURE-BASED FORCE-LIMITING MECHANISM

Copyright © 2019 by ASME. A force-limiting buckling flexure has been created which can be used in a wide range of applications where excessive force from an implement can cause harm or damage. The buckling flexure is monolithic, contains no electronics, and can be manufactured using a single shot in an injection molding machine, making it cost effective. In this paper, the design of the flexure is applied to a force-limiting toothbrush as a design study to show its application in a real-world technology. An overview of the buckling flexure is presented, and a structural model is presented to predict when the flexure will elastically buckle. Flexures of different geometries were tested and buckled. The data show that the model can predict buckling of the flexure with an error of 20.84%. A finite element model was also performed which predicts buckling of the flexure within an error of 25.35%. Furthermore, a preliminary model is presented which enables the design of the buckling beam's displacement, such that the total breakaway deformation can be maximized, making sensing the sudden deformation easier to detect. As part of the application of the buckling flexure, an ergonomic, injection moldable toothbrush was created with the flexure built into the neck of the brush. When the user applies too much force while brushing, the flexure gives way and alerts the user when they have applied too much force; when the user lets off the force, the brush snaps back to its original shape. This design methodology is generalized and can be utilized in other force limited applications where an injection-moldable, pre-set force, and purely mechanical breakaway device is desired