Northernmost (?) Glacial Lake Algonquin Series Shorelines,Sudbury Basin,Ontario

Shorelines of Lake Algonquin, the largest of the glacial lakes of the Great Lakes area, are well known in southern Ontario, but are sporadic and difficult to trace northward onto the Precambrian shield. Improved knowledge of the extent and uplift pattern for Algonquin shorelines is needed to support geophysical models of isostatic response, interpretation of glacial and glacial lake history, and the search by archeologists for evidence of Paleoindian activity, shown to be localized along its shoreline. The Sudbury basin is one of the few areas of mapping of Quaternary geology on the Canadian shield that provides a record of Algonquin lake phases. Meltwaters from the northward-receding ice front formed a series of deltas southward into the Sudbury basin in central Ontario around the time the Cartier I moraine was deposited. Instrumental surveys of deltas, bars, and shorebluffs carried out in the northern Sudbury basin delineate several discrete water planes. Correlation with previously surveyed and correlated shorelines on Manitoulin Island, southwest of Sudbury, indicates the presence of an upper Algonquin shoreline and features correlated to the Cedar Point, Payette, Sheguiandah, and Korah levels. Features southwest of the Sudbury basin at Nairn correlate with Korah and post-Korah water levels. Land between Nairn and Sudbury is too elevated to have been reached by the later Nipissing transgression. Similar shoreline sequences have been surveyed near North Bay, with results supporting the findings of this study.     

What is the value of limited feedback for MIMO channels?

Feedback in a communications system can enable the transmitter to exploit channel conditions and avoid interference. In the case of a multiple-input multiple-output channel, feedback can be used to specify a precoding matrix at the transmitter, which activates the strongest channel modes. In situations where the feedback is severely limited, important issues are how to quantize the information needed at the transmitter and how much improvement in associated performance can be obtained as a function of the amount of feedback available. We give an overview of some recent work in this area. Methods are presented for constructing a set of possible precoding matrices, from which a particular choice can be relayed to the transmitter. Performance results show that even a few bits of feedback can provide performance close to that with full channel knowledge at the transmitter.     

Modelling realistic electromagnetic effects on MIMO system capacity

Computational electromagnetics is used to characterise the effect of realistic propagation on the capacity of multiple-input, multiple-output (MIMO) communication systems. Mutual information results for a MIMO system operating at 1.8 GHz in an urban micro-cellular environment are presented.     

Is there "feedback" during visual imagery? Evidence from a specificity of practice paradigm.

The specificity of practice hypothesis predicts the development of a sensorimotor representation specific to the afferent feedback available during skill acquisition (Proteau, 1992; Proteau, Marteniuk, Girouard, & Dugas, 1987). In the present investigation, we used the specificity of practice hypothesis to test whether skill acquisition through visual imagery would lead to the development of a sensory-specific movement representation similar to one resulting from actual practice. To accomplish this objective, participants practiced walking a 12-m linear path in one of three practice conditions, full-vision (FV), no-vision (NV), or visual imagery (VI), for either 10 or 100 trials. Knowledge of spatial and/or temporal results (KR) was provided to participants following each trial during this phase. Following acquisition, participants completed 10 NV trials without KR. An analysis of root-mean-squared-error (RMSE) indicated NV participants were more accurate than both FV and VI participants in the transfer condition. We believe the equivalence in transfer RMSE between FV and VI suggests that there are similarities between the movement representations attained by FV and VI practice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adaptive modulation and MIMO coding for broadband wireless datanetworks

Link adaptation techniques, where the modulation, coding rate, and/or other signal transmission parameters are dynamically adapted to the changing channel conditions, have emerged as powerful tools for increasing the data rate and spectral efficiency of wireless data-centric networks. While there has been significant progress on understanding the theoretical aspects of time adaptation in LA protocols, new challenges surface when dynamic transmission techniques are employed in broadband wireless networks with multiple signaling dimensions. Those additional dimensions are mainly frequency, especially in multicarrier systems, and space in multiple-antenna systems, particularly multiarray multiple-input multiple-output communication systems. We give an overview of the challenges and promises of link adaptation in future broadband wireless networks. We suggest guidelines to help in the design of robust, complexity/cost-effective algorithms for these future wireless networks     

An Investigation into Zinc Diffusion and Tin Whisker Growth for Electroplated Tin Deposits on Brass

It is widely documented that whisker growth is more rapid for tin deposits on brass compared with deposits produced on other substrate materials, such as copper. As a result, studies investigating the effect of process variables on tin whisker formation are often conducted on brass substrates to take advantage of the increased whisker growth rates. Although it has been understood since the 1960s that the increased whisker growth results from zinc diffusion, to date there has not been any detailed analysis of the zinc/zinc oxide distribution at the surface of the tin deposit. Using a commercial bright tin electroplating bath, the formation of zinc oxide at the surface of tin deposits on brass has been investigated. Analyses show that zinc oxide is present on the surface of the deposit within 1 day of electroplating. During storage at room temperature, a network of zinc oxide is formed at the surface grain boundaries, the extent of which increases with time. The critical role that zinc surface diffusion plays in whisker growth for tin deposits on brass has been demonstrated by electrochemical oxidation of the tin shortly after electroplating. This develops a tin oxide film that is thicker than the native air-formed oxide and subsequently serves as a diffusion barrier to zinc surface diffusion, thereby mitigating whisker growth.