A mathematical model of three-dimensional flow in a scraped-surface heat exchanger

We present a simple mathematical model of fluid flow in a Scraped-Surface Heat Exchanger (SSHE). Specifically we consider steady isothermal flow of a Newtonian fluid around a periodic array of pivoted scraper blades in a channel with one stationary and one moving wall, when there is an applied pressure gradient in a direction perpendicular to the wall motion. The flow is fully three-dimensional, but decomposes naturally into a two-dimensional transverse flow driven by the boundary motion and a longitudinal pressure-driven flow

Methodological Considerations in Pretrial Publicity Research: Is the Medium the Message?

Two methodological issues within the pretrial publicity (PTP) literature were examined in the present experiment: the effect of emotional versus factual PTP and the effect of presenting PTP through different media. Emotional and factual PTP were constructed that differed in level of emotionality, but produced the same degree of bias. The PTP was presented in either a videotaped or written format. Although there was a significantly biasing effect of PTP overall compared to a control condition, no significant difference was found either between factual and emotional PTP or between video and written PTP

Aggressive International Tax Planning by Multinational Corporations: The Canadian Context and Possible Responses

Aggressive international tax planning by multinational corporations has lately fallen under intense political scrutiny. U.S. politicians have called out some American multinationals, including Apple, Amazon, Starbucks and Google, for relocating profits abroad to avoid American taxes. More recently, politicians accused Burger King of being unpatriotic for its own purported “tax inversion” maneuver, in which it would acquire Canada’s Tim Hortons and shift the head office from Florida to Ontario, benefitting from the lower northern tax rates. The Chicago-based Walgreens pharmacy chain recently backed off a “tax inversion” plan to relocate to Switzerland (the former headquarters of Alliance Boots, a company acquired by Walgreens), apparently having assessed the political risk as too high. This sort of aggressive international tax planning by multinational corporations was what G20 members had committed to fighting against when they endorsed the OECD’s “action plan” against base erosion and profit shifting (BEPS). Canada has been vigilant about improving its tax framework to prevent non-resident corporations from eroding the Canadian tax base, having enacted thin-capitalization rules and, more recently, foreign-affiliate-dumping rules, as well as proposing anti-treaty-shopping measures. But despite Canada’s commitment to the OECD’s BEPS Action Plan, the Canadian government has been reluctant to follow through on implementing rules that might affect its own resident corporations and their international competitiveness. This is most notably visible in the generous participation exemption for dividends from foreign affiliates, the absence of rules restricting the deductibility of interest expenses incurred to earn exempt dividends from foreign affiliates. Canada may be reluctant to fully follow through on all aspects of the OECD’s BEPS Action Plan. As the examples of Apple, Amazon, Google and Starbucks demonstrate, the American government has so far been unable to bring itself to take any meaningful action against aggressive international planning by U.S.resident corporations. Were Canada to enact and enforce rules that clamped down on aggressive international tax planning by its own resident corporations, it would only put Canadian firms at a competitive disadvantage relative to American (or other international) rivals. Until the United States is willing and able to take the lead on aggressive international tax planning by multi-national corporations, the reality is that smaller countries, including Canada, should be cautious about making changes to its international tax rules that are dependent on other countries making similar changes

Methodological Considerations in Pretrial Publicity Research: Is the Medium the Message?

Two methodological issues within the pretrial publicity (PTP) literature were examined in the present experiment: the effect of emotional versus factual PTP and the effect of presenting PTP through different media. Emotional and factual PTP were constructed that differed in level of emotionality, but produced the same degree of bias. The PTP was presented in either a videotaped or written format. Although there was a significantly biasing effect of PTP overall compared to a control condition, no significant difference was found either between factual and emotional PTP or between video and written PTP

Early Surgery for Traumatic Spinal Cord Injury: Where Are We Now?

Study Design: Narrative review. Objective: There is a strong biological rationale to perform early decompression after traumatic spinal cord injury (SCI). With an enlarging clinical evidence base, most spine surgeons internationally now favor early decompression for the majority of SCI patients; however, a number of pertinent questions remain surrounding this therapy. Methods: A narrative review evaluating the status of early surgery for SCI. In particular, we addressed the following questions: (1) Which patients stand to benefit most from early surgery? 2) What is the most appropriate time threshold defining early surgery? Results: Although heterogeneity exists, the evidence generally seems to support early surgery. While the best evidence exists for cervical SCI, there is insufficient data to support a differential effect for early surgery depending on neurological level or injury severity. When comparing thresholds to define early versus late surgery-including a later threshold (48-72 hours), an earlier threshold (24 hours), and an ultra-early threshold (8-12 hours)-the 2 earlier time points seem to be associated with the greatest potential for improved outcomes. However, existing prehospital and hospital logistics pose barriers to early surgery in a significant proportion of patients. An overview of recommendations from the recent AOSpine guidelines is provided. Conclusion: In spite of increasing acceptance of early surgery post SCI, further research is needed to (1) identify subgroups of patients who stand to derive particular benefit-in particular to develop more evidence-based approaches for central cord syndrome and (2) investigate the efficacy and feasibility of ultra-early surgery targeting more aggressive timelines

Screw and Pin Fastener Tests for Cold-Formed Steel

Because of limited available information on strength and ease of installation of specific fasteners for a particular application to a steel deck diaphragm, a preliminary testing program comparing the shear strength of commercially available screws and gas-actuated shot pins was conducted by J. R. Harris and Company at the University of Colorado Denver in 2018. A test was designed to explore the behavior and capacity of various fasteners, securing two and three pieces of sheet steel of various thicknesses together. Specimens were fabricated and load tested, with the sheet steel pieces in tension, so the fasteners were subject to shear. Four fasteners, in two rows of two, were used for all tests, with different end distances also being studied. Most of the tests were monotonic tension, and those results were used to develop a cyclic testing protocol for the best performing screw and shot pin. Most limit states encountered were limited by tilting of the screw against the sheet steel in bearing, leading to a ductile failure. Fastener shear was encountered in a small percentage of cases. Results are compared to each other and to AISI calculated values

Travelling-wave similarity solutions for an unsteady shear-stress-driven dry patch in a flowing film

We investigate unsteady flow of a thin film of Newtonian fluid around a symmetric slender dry patch moving with constant velocity on an inclined planar substrate, the flow being driven by a prescribed constant shear stress at the free surface of the film (which would be of uniform thickness in the absence of the dry patch). We obtain a novel unsteady travelling-wave similarity solution which predicts that the dry patch has a parabolic shape and that the film thickness increases monotonically away from the dry patch