On-board processing satellite network architecture and control study

The market for telecommunications services needs to be segmented into user classes having similar transmission requirements and hence similar network architectures. Use of the following transmission architecture was considered: satellite switched TDMA; TDMA up, TDM down; scanning (hopping) beam TDMA; FDMA up, TDM down; satellite switched MF/TDMA; and switching Hub earth stations with double hop transmission. A candidate network architecture will be selected that: comprises multiple access subnetworks optimized for each user; interconnects the subnetworks by means of a baseband processor; and optimizes the marriage of interconnection and access techniques. An overall network control architecture will be provided that will serve the needs of the baseband and satellite switched RF interconnected subnetworks. The results of the studies shall be used to identify elements of network architecture and control that require the greatest degree of technology development to realize an operational system. This will be specified in terms of: requirements of the enabling technology; difference from the current available technology; and estimate of the development requirements needed to achieve an operational system. The results obtained for each of these tasks are presented

New Media and Youth Political Action

To rigorously consider the impact of new media on the political and civic behavior of young people, The MacArthur Research Network on Youth and Participatory Politics (YPP) developed and fielded one of the first large-scale, nationally representative studies of new media and politics among young people. The two principal researchers for the survey component of the YPP, Cathy J. Cohen of the University of Chicago and Joseph Kahne of Mills College, oversaw a research team that surveyed nearly 3,000 respondents between the ages of 15 and 25 years of age. Unlike any prior study of youth and new media, this study included large numbers of black, Latino, and Asian American respondents, which allows for unique and powerful statistical comparisons across race with a focus on young people.Until now there has been limited opportunity and data available to comprehensively explore the relationship between new media and the politics of young people. One of the few entities to engage in this type of rigorous analysis has been the Pew Internet and American Life Project. The YPP study expands on this field-leading work by including an extensive battery of items addressing participatory politics and adequate numbers of participants from different racial and ethnic groups, thus allowing for analysis of how different groups of young people were engaged with new media in the political realm.The YPP study findings suggest that fundamental changes in political expectations and practices may be occurring -- especially for youth. The analysis of the data collected reveals that youth are taking advantage of an expanded set of participatory practices in the political realm in ways that amplify their voice and sometimes their influence, thus increasing the ways young people participate in political life. The YPP researchers label this expanded set of opportunities and actions participatory politics

Technology and connection in the deaf world

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 27-30).In 1984, the FDA approved a medical device called a cochlear implant for adult use in the United States. Unlike assistive hearing technologies that came before it, such as hearing aids, cochlear implants could offer wider access to sound even to the profoundly deaf. Given adult success with the device, the FDA lowered in 1990 the required age for implantation to two years old. The following year the National Association of the Deaf published a position statement on cochlear implants comparing them to "cultural genocide." This thesis explores two parallel stories. Drawing on interviews with implant engineers, surgeons, audiologists, and other specialists, the piece describes how cochlear implants function and how the devices have improved since the 1980s. Equally, the thesis pulls from interviews with bioethicists, deaf and hard of hearing individuals, educators at a signing deaf school, and others in the deaf community to describe the unique attributes and history of deaf culture and the changing and diverse reactions of the deaf community to this medical device.by Joseph Benjamin Calamia.S.M.in Science Writin

Cigarette Taxes and the Social Market

Previous researchers have argued that the social market for cigarettes insulates its participants from policies designed to curb youth smoking. Using state Youth Risk Behavior Survey data, we examine whether recent changes in state cigarette taxes affected how young smokers obtained their cigarettes. Our estimates suggest that tax increases reduce youth smoking participation primarily through their effect on third-party purchase, although there is evidence that they are negatively related to borrowing among younger teenagers and negatively related to direct purchase among older teenagers.youth smoking, cigarette taxes

Extending the memory times of trapped-ion qubits with error correction and global entangling operations

The technical demands to perform quantum error correction are considerable. The task requires the preparation of a many-body entangled state, together with the ability to make parity measurements over subsets of the physical qubits of the system to detect errors. Here we propose two trapped-ion experiments to realise error-correcting codes of variable size to protect a single encoded qubit from dephasing errors. Novel to our schemes is the use of a global entangling phase gate, which could be implemented in both Penning traps and Paul traps. We make use of this entangling operation to significantly reduce the experimental complexity of state preparation and syndrome measurements. We also show, in our second scheme, that storage times can be increased further by repeatedly teleporting the logical information between two codes supported by the same ion Coulomb crystal to learn information about the locations of errors. We estimate that a logical qubit encoded in such a crystal will maintain high coherence for times more than an order of magnitude longer than each physical qubit would.Comment: 18 pages, 8 figures. The authors list has changed since the first version of this draf