Effect of lateral displacement of a high-altitude platform on cellular interference and handover

A method for predicting movements in cellular coverage caused by lateral drift of a high-altitude platform (a quasi-stationary platform in the stratosphere) is developed. Cells are produced by spot beams generated by horn-type antennas on the platform. It is shown how the carrier-to-interference ratio (CIR) across these cells varies when the antenna payload is steered to accommodate the lateral movement of the platform. The geometry of the antenna beam footprint on the ground is first developed and then applied to a system of many cochannel beams. Pointing strategies are examined, where the pointing angle is calculated to keep, for example, a center cell or an edge cell in the same nominal position before and after the platform drift, and the CIR distribution is calculated. It is shown that the optimum pointing angle depends on the desired level of CIR across the service area, typically lying between 3 +/- 0.75 degrees for a platform drift of 2'km and corresponding to a cell in the middle ring. It is shown that it is necessary for a significant proportion of users to perform a handover to maintain a given CIR after platform drift. The analysis reveals that there is an optimum pointing angle that minimizes the probability of handover for a particular value of drift and CIR

Field Guide to the Searobins (Prionotus and Bellator) in the Western North Atlantic

Species identifications of Prionotus and Bellator are often difficult under field conditions owing to the large number of species and their overlapping taxonomic characteristics. This key is intended to provide a simplified, accurate means to identify adult searobins greater than 10 cm standard length. All recognized species from the western North Atlantic, the Gulf of Mexico, and Caribbean Sea are included. (PDF file contains 30 pages.

A dysphoric's TALE: The relationship between the self-reported functions of autobiographical memory and symptoms of depression

Autobiographical memory (AM) is believed to serve self, social and directive functions; however, little is known regarding how this triad of functions operates in depression. Using the Thinking About Life Experiences questionnaire [Bluck, S., & Alea, N. (2011). Crafting the TALE: Construction of a measure to assess the functions of autobiographical remembering. Memory, 19, 470–486.; Bluck, S., Alea, N., Habermas, T., & Rubin, D. C. (2005). A TALE of three functions: The self–reported uses of autobiographical memory. Social Cognition, 23, 91–117.], two studies explored the relationship between depressive symptomology and the self-reported frequency and usefulness of AMs for self, social and directive purposes. Study 1 revealed that thinking more frequently but talking less frequently about past life events was significantly associated with higher depression scores. Recalling past events more frequently to maintain self-continuity was also significantly associated with higher depressive symptomology. However, results from Study 2 indicated that higher levels of depression were also significantly associated with less-frequent useful recollections of past life events for self-continuity purposes. Taken together, the findings suggest atypical utilisations of AM to serve self-continuity functions in depression and can be interpreted within the wider context of ruminative thought processes

Singing the Brain Electric

Thesis (S.M. in Science Writing)--Massachusetts Institute of Technology, Dept. of Humanities, Graduate Program in Science Writing, 2008.Includes bibliographical references (p. [36]-[38]).Singing the Brain Electric Brain pacemakers, scientists have found, can treat depression by correcting neural circuitry gone haywire. This thesis examines how such technology - a technique known as deep-brain stimulation, in which electrodes are implanted within the brain - was developed and how it works. We are introduced to a patient who received deep-brain stimulation for her refractory depression, and consider the risks, ethical issues, and questions of humanity and identity the technology raises.by Grace Chua.S.M.in Science Writin

Survival processing versus self-reference : a memory advantage following descriptive self-referential encoding

Previous research has shown that rating words for their relevance to a survival scenario leads to better retention of the words than rating them for self-reference. Past studies have, however, relied exclusively on an autobiographical self-reference task in which participants rate how easily a common noun brings to mind a personal experience. We report five experiments comparing survival processing to a descriptive self-reference task in which participants rated how well trait words described them. Rating trait adjectives for survival value led to higher levels of recall and recognition than rating them for their relevance to a moving home scenario. Rating the adjectives for self-reference, however, led to higher levels of recall (Experiments 1 and 3) and recollection (Experiment 2) than survival rating. Experiment 4 replaced trait adjectives with trait nouns and found that self-reference led to greater recognition accuracy than survival processing. Experiment 5 used trait nouns followed by tests of free recall and found a memory advantage following self-reference that was not influenced by the imageability of the stimuli. The findings are discussed in terms of theories of the survival processing and self-reference effects and the relationship between them

Improving the system capacity of broadband services using multiple high-altitude platforms

A method of significantly improving the capacity of high-altitude platform (HAP) communications networks operating in the millimeter-wave bands is presented. It is shown how constellations of HAPs can share a common frequency allocation by exploiting the directionality of the user antenna. The system capacity of such constellations is critically affected by the minimum angular separation of the HAPs and the sidelobe level of the user antenna. For typical antenna beamwidths of approximately 5/spl deg/ an inter-HAP spacing of 4 km is sufficient to deliver optimum performance. The aggregate bandwidth efficiency is evaluated, both theoretically using the Shannon equation, and using practical modulation and coding schemes, for multiple HAP configurations delivering either single or multiple cells. For the user antenna beamwidths used, it is shown that capacity increases are commensurate with the increase in the number of platforms, up to 10 HAPs. For increases beyond this the choice of constellation strategy becomes increasingly important

Clinical impact of splicing in neurodevelopmental disorders.

Clinical exome sequencing is frequently used to identify gene-disrupting variants in individuals with neurodevelopmental disorders. While splice-disrupting variants are known to contribute to these disorders, clinical interpretation of cryptic splice variants outside of the canonical splice site has been challenging. Here, we discuss papers that improve such detection