Community Building With And For Teachers At The Math Forum

This chapter addresses the way in which the Internet forms the core of an intentional, online community by promoting communication between interested parties. The Math Forum (mathforum.org) is a unique group of individuals who are committed to using computers and the Internet to enhance what they know about learning, teaching, and doing mathematics. The Math Forum includes programmers, project and service staff, Web persons, and an ever-expanding number of teachers, students, and other individuals (i.e., parents, software developers, mathematicians). Thus, community building for The Math Forum staff includes work with teachers, with partners (National Council of the Teachers of Mathematics, Mathematics Association of America, and so on), and with specific services developed by The Math Forum staff that enable teachers and students to come together to pose and seek solutions to problems. The Math Forum uses the Internet to provide interactive services that foster mathematical thinking and discussion. These services include Ask Dr. Math and several Problems of the Week (PoWs); a teacher discussion format called Teacher to Teacher (T2T); an archive of problems, participant contributions (e.g., lesson plans), and past discussions; and an Internet newsletter. Within four years, with no explicit efforts to garner promotion or publicity, the site grew to include 1,600,000 Web pages and to attract 3.5 million accesses and over 800,000 visitors per month – a third of which constitutes sticky traffic ranging from world-famous mathematicians to elementary school children

The Centrality Of Culture And Community To Participant Learning At And With The Math Forum

In this chapter, the terms culture and community are problematized, and their centrality to participant learning at and with The Math Forum (mathforum.org) is discussed. Culture, as it is used here, refers to the rituals and norms that come to be associated with a site and its functioning. Community describes recognition of connections to and identification with other participants. The Math Forum is an interactive and inquiry-informed digital library, or virtual resource center, for mathematics education. Previous chapters have addressed the ways in which The Math Forum has leveraged the concept of community in order to become a dynamic and resource-rich educational site (Renninger & Shumar, 2002; Shumar & Renninger, 2002). In the present chapter, this analysis is taken a step further. The culture of The Math Forum is described as providing its participants with a unique set of opportunities for learning and for making the relationship between the individual and the community one in which individual and community needs can both be met. Site culture enables contributions from individuals that by definition help to build out and sustain this community. Math Forum participants include Math Forum staff members and a mix of teachers, students, and other individuals such as parents, software developers, mathematicians, math educators, professionals, and tradespeople, many of whom also volunteer their time as mentors for the site. Participants differ not only in terms of their roles, but in their experience, level of expertise, and interest for mathematics (Renninger & Shumar, 2002)

Pulse generation without gain-bandwidth limitation in a laser with self-similar evolution

With existing techniques for mode-locking, the bandwidth of ultrashort pulses from a laser is determined primarily by the spectrum of the gain medium. Lasers with self-similar evolution of the pulse in the gain medium can tolerate strong spectral breathing, which is stabilized by nonlinear attraction to the parabolic self-similar pulse. Here we show that this property can be exploited in a fiber laser to eliminate the gain-bandwidth limitation to the pulse duration. Broad (̃200 nm) spectra are generated through passive nonlinear propagation in a normal-dispersion laser, and these can be dechirped to ̃20-fs duration

Design of an In-Situ Sensor Package to Track CubeSat Deployments

Currently, radar measurements of low-earth-orbit CubeSats are only possible during a small portion of a CubeSat’s orbit – typically long after the CubeSat’s deployment – making near real-time space situational awareness (SSA) difficult. The CU Boulder Smead Aerospace Engineering Department has developed a concept to monitor CubeSat deployments from the deployer itself and provide relative position and velocity measurements of deployed payloads to provide faster orbital parameter estimation. Teaming with NanoRacks LLC, the VANTAGE team (Visual Approximation of Nanosat Trajectories to Augment Ground-based Estimation) has developed an innovative sensor package prototype consisting of an Infra-red (IR) Time of Flight (ToF) camera for close-range CubeSat position measurements and a monochrome optical camera for continued detection and in-plane position refinement, as well as a set of algorithms to process and fuse these CubeSat position measurements. These sensors and their avionics are incorporated into a prototype integrated system designed to fit within a single 6U CubeSat Deployment silo on the NanoRacks ISS deployer, enabling the detection, identification, and tracking of up to 6 CubeSats out to 100m with a maximum positional error of 10m within 15 minutes of deployment

Synthetic biology and biomass conversion: a match made in heaven?

To move our economy onto a sustainable basis, it is essential that we find a replacement for fossil carbon as a source of liquid fuels and chemical industry feedstocks. Lignocellulosic biomass, available in enormous quantities, is the only feasible replacement. Many micro-organisms are capable of rapid and efficient degradation of biomass, employing a battery of specialized enzymes, but do not produce useful products. Attempts to transfer biomass-degrading capability to industrially useful organisms by heterologous expression of one or a few biomass-degrading enzymes have met with limited success. It seems probable that an effective biomass-degradation system requires the synergistic action of a large number of enzymes, the individual and collective actions of which are poorly understood. By offering the ability to combine any number of transgenes in a modular, combinatorial way, synthetic biology offers a new approach to elucidating the synergistic action of combinations of biomass-degrading enzymes in vivo and may ultimately lead to a transferable biomass-degradation system. Also, synthetic biology offers the potential for assembly of novel product-formation pathways, as well as mechanisms for increased solvent tolerance. Thus, synthetic biology may finally lead to cheap and effective processes for conversion of biomass to useful products

High-Energy Passive Mode-Locking of Fiber Lasers

Mode-locking refers to the generation of ultrashort optical pulses in laser systems. A comprehensive study of achieving high-energy pulses in a ring cavity fiber laser that is passively mode-locked by a series of waveplates and a polarizer is presented in this paper. Specifically, it is shown that the multipulsing instability can be circumvented in favor of bifurcating to higher-energy single pulses by appropriately adjusting the group velocity dispersion in the fiber and the waveplate/polarizer settings in the saturable absorber. The findings may be used as practical guidelines for designing high-power lasers since the theoretical model relates directly to the experimental settings

Pulse generation without gain-bandwidth limitation in a laser with self-similar evolution

With existing techniques for mode-locking, the bandwidth of ultrashort pulses from a laser is determined primarily by the spectrum of the gain medium. Lasers with self-similar evolution of the pulse in the gain medium can tolerate strong spectral breathing, which is stabilized by nonlinear attraction to the parabolic self-similar pulse. Here we show that this property can be exploited in a fiber laser to eliminate the gain-bandwidth limitation to the pulse duration. Broad (∼200 nm) spectra are generated through passive nonlinear propagation in a normal-dispersion laser, and these can be dechirped to ∼20-fs duration