IWR; no. 96

A report of a workshop held at The University of Alberta, Edmonton on March 20, 1978.The Joint Canadian-United States Northern Civil Engineering Research Workshop was held at the University of Alberta campus, Edmonton, Alberta on March 20 through 22, 1978. Over 40 participants from government, universities, and private practice from both the U.S. and Canada discussed northern civil engineering research for 2 1/2 days. The results of their effort are presented in this report. The nature of a report coming from spontaneous conversation will be somewhat uneven in coverage, language, and tone. However, we feel obligated to preserve the initial intent and language of the various workshop groups and each report should represent the original conclusion as nearly as possible. We acted as the principal instigators of the workshop and were ably assisted by an excellent group of workshop chairmen: Jack Clark, Lorne Gold, Charles Neill, Daniel Rogness, James Rooney, and Daniel Smith. We particularly want to acknowledge the assistance of the Boreal Institute for organizing and providing much of the administrative and secretarial support for the workshop, and the staff of the Institute of Water Resources for assisting with the organizing and publication processes. The workshop was sponsored by the National Science Foundation of the United States, the Department of Indian and Northern Affairs of Canada, the Boreal Institute and Department of Civil Engineering of the University of Alberta, and the Institute of Water Resources of the University of Alaska. R. F. Carlson N. R. MorgensternNSF Grant No. ENG 76-22293 Department of Indian and Northern Affairs Grant 64-0502

INA complex liaises the F1Fo-ATP synthase membrane motor modules.

The F1F0-ATP synthase translates a proton flux across the inner mitochondrial membrane into a mechanical rotation, driving anhydride bond formation in the catalytic portion. The complex's membrane-embedded motor forms a proteinaceous channel at the interface between Atp9 ring and Atp6. To prevent unrestricted proton flow dissipating the H+-gradient, channel formation is a critical and tightly controlled step during ATP synthase assembly. Here we show that the INA complex (INAC) acts at this decisive step promoting Atp9-ring association with Atp6. INAC binds to newly synthesized mitochondrial-encoded Atp6 and Atp8 in complex with maturation factors. INAC association is retained until the F1-portion is built on Atp6/8 and loss of INAC causes accumulation of the free F1. An independent complex is formed between INAC and the Atp9 ring. We conclude that INAC maintains assembly intermediates of the F1 F0-ATP synthase in a primed state for the terminal assembly step-motor module formation

Exploiting the Temporal Logic Hierarchy and the Non-Confluence Property for Efficient LTL Synthesis

The classic approaches to synthesize a reactive system from a linear temporal logic (LTL) specification first translate the given LTL formula to an equivalent omega-automaton and then compute a winning strategy for the corresponding omega-regular game. To this end, the obtained omega-automata have to be (pseudo)-determinized where typically a variant of Safra's determinization procedure is used. In this paper, we show that this determinization step can be significantly improved for tool implementations by replacing Safra's determinization by simpler determinization procedures. In particular, we exploit (1) the temporal logic hierarchy that corresponds to the well-known automata hierarchy consisting of safety, liveness, Buechi, and co-Buechi automata as well as their boolean closures, (2) the non-confluence property of omega-automata that result from certain translations of LTL formulas, and (3) symbolic implementations of determinization procedures for the Rabin-Scott and the Miyano-Hayashi breakpoint construction. In particular, we present convincing experimental results that demonstrate the practical applicability of our new synthesis procedure

Where and Why Do Coastal Retrogressive Thaw Slumps Develop?

Retrogressive thaw slumps (RTSs) are among the most active landforms in the Arctic; their number has increased tremendously over the past decades. While processes initiating discrete RTSs are well defined, little research has been done on a regional scale to reveal the major terrain controls on their development. Our research provides new insights into the dynamics of coastal RTSs. We reveal the main geomorphic factors determining the development of RTSs along a 238 km coastal segment of the Yukon Coastal Plain, Canada. We 1) show the current extent of RTSs, 2) ascertain the factors controlling their activity and initiation, and 3) explain the differences in density and coverage of RTSs. We mapped and classified the RTSs based on high-resolution satellite images acquired in 2011. We derived the terrain characteristics for each RTS and highlighted the main terrain controls over their development using univariate regression trees. We tested the response variables (RTSs activity, initiation, density and coverage) against 16 environmental variables. We detected 287 coastal RTSs in the study area. Both the activity and the initiation of the RTSs were influenced by coastal geomorphology: active RTSs and new RTSs occurred primarily on terrain with slope angles greater than 3.9° and 5.9°, respectively. The density and coverage of RTSs within each coastal segment were constrained by the volume and thickness of massive ice bodies. Coastal erosion appears to have only an indirect effect on the development of RTSs by maintaining the best conditions for RTSs to reactivate

On the thermodynamics of first-order phase transition smeared by frozen disorder

The simplified model of first-order transition in a media with frozen long-range transition-temperature disorder is considered. It exhibits the smearing of the transition due to appearance of the intermediate inhomogeneous phase with thermodynamics described by the ground state of the short-range random-field Ising model. Thus the model correctly reproduce the persistence of first-order transition only in dimensions d > 2, which is found in more realistic models. It also allows to estimate the behavior of thermodynamic parameters near the boundaries of the inhomogeneous phase.Comment: 4 page

A Case History of Liquefaction Flow Failures in Mountains Mine Waste Dumps

Over the past 25 years there have been a large number of flowslides in Rocky Mountain coal mine waste dumps located in British Columbia, Canada. The flowslides occurred rapidly and displayed surprisingly long distance of runout up to 2 km. Detailed field, laboratory studies, and analyses indicate that static collapse of saturated or nearly saturated sandy gravel layers within the dumps are responsible for the initial failure and ensuing flow failures. In addition to field and laboratory studies, finite element analyses were carried out on three case histories. The analysis results indicated that the flow like liquefaction failures of these waste dumps can be triggered by gradually raising of perched water tables contained within thin layers or poorly draining waste material in these slopes. This paper reviews the site condition and failure pattern observed in the mountainous mine waste dumps and investigates the mechanism of static liquefaction failure by finite element methods

Linear-time list recovery of high-rate expander codes

We show that expander codes, when properly instantiated, are high-rate list recoverable codes with linear-time list recovery algorithms. List recoverable codes have been useful recently in constructing efficiently list-decodable codes, as well as explicit constructions of matrices for compressive sensing and group testing. Previous list recoverable codes with linear-time decoding algorithms have all had rate at most 1/2; in contrast, our codes can have rate $1 - \epsilon$ for any $\epsilon > 0$. We can plug our high-rate codes into a construction of Meir (2014) to obtain linear-time list recoverable codes of arbitrary rates, which approach the optimal trade-off between the number of non-trivial lists provided and the rate of the code. While list-recovery is interesting on its own, our primary motivation is applications to list-decoding. A slight strengthening of our result would implies linear-time and optimally list-decodable codes for all rates, and our work is a step in the direction of solving this important problem

Direct and ozone-mediated forcing of the Southern Annular Mode by greenhouse gases

We assess the roles of long-lived greenhouse gases and ozone depletion in driving meridional surface pressure gradients in the southern extratropics; these gradients are a defining feature of the Southern Annular Mode. Stratospheric ozone depletion is thought to have caused a strengthening of this mode during summer, with increasing long-lived greenhouse gases playing a secondary role. Using a coupled atmosphere-ocean chemistry-climate model, we show that there is cancelation between the direct, radiative effect of increasing greenhouse gases by the also substantial indirect—chemical and dynamical—feedbacks that greenhouse gases have via their impact on ozone. This sensitivity of the mode to greenhouse gas-induced ozone changes suggests that a consistent implementation of ozone changes due to long-lived greenhouse gases in climate models benefits the simulation of this important aspect of Southern Hemisphere climate