Nilpotent Completely Positive Maps

We study the structure of nilpotent completely positive maps in terms of Choi-Kraus coefficients. We prove several inequalities, including certain majorization type inequalities for dimensions of kernels of powers of nilpotent completely positive maps.Comment: 10 page

Systematic Survey of the Role of IGF in the Link Between Diabetes and Cancer

Epidemiological studies have proposed a link between type II diabetes and cancer via the IGF/insulin signaling pathway, which includes insulin-like peptides (IGF1, IGF2, and insulin), insulin receptors (IR-A, IR-B, IGF1R, and hybrids), and insulin substrate proteins (IRS1-6). In this study, up- and down-regulation of various components in the IGF/insulin signaling pathway are compared to clinical outcomes for cancer patients; the components include diagnosis age, overall survival, tumor invasion and vascularization, and body mass index. It was found that the up-regulation of insulin growth Factor (IGF)/insulin components was associated with overall survival and tumor invasion and vascularization, while the down-regulation of equivalent components was not associated with clinical outcomes assessed in this study. Particularly, the up-regulation of DOK5, IGF2, and IRS2 in colorectal cancer and IGF1R in liver cancer is associated with significantly decreased overall survival. Functional aberrations in either of the two proteins in co-expression pairs were identified for each cancer and correlated with overall survival and diagnosis age. Specific biomarkers proposed in this study will be further analyzed to fine-tune consistent associations that can be translated to reliable prognostic standards for the roles of IGF/insulin signaling pathway modulations that promote cancer

Deferred Tax Positions and Incentives for Corporate Behavior Around Corporate Tax Changes

A firm's deferred tax position can influence how it is affected by a transition from one tax regime to another. We compile disaggregated deferred tax position data for a sample of large U.S. firms between 1993 and 2004 to explore how these positions might affect firm behavior before and after a pre-announced change in the statutory corporate tax rate. Our results suggest that the heterogeneous deferred tax positions of large U.S. corporations create substantial variation in the short-run effect of tax rate changes on reported earnings. Recognizing these divergent incentives is important for understanding the political economy of corporate tax reform.

Ending the R&D Tax Credit Stalemate

The 113th Congress extended the research and development (R&D) tax credit through the end of 2014 by passing the Tax Increase Prevention Act (H.R. 5771), which President Obama signed into law on December 19, 2014. That the fate of this credit in 2015 remains unknown is not surprising. This brief explores the history, logistics, and policy implications of the temporary R&D tax credit, and offers recommendations for additional research that would help determine the merit of making the credit permanent. Using new, restricted-access IRS data and an instrumental variables strategy, the brief offers an unbiased estimation of the effectiveness of the R&D tax credit, showing that corporate research intensity—the ratio of R&D spending to sales—is indeed highly sensitive to the tax subsidy rate. When it gets cheaper for firms to spend on qualified R&D, they actually do spend more, as policymakers hope.https://repository.upenn.edu/pennwhartonppi/1027/thumbnail.jp

Tsunamis Cannot Be Predicted Based on the Past

At present, there are no patterns that can be used to predict when a tsunami will occur.York's Knowledge Mobilization Unit provides services and funding for faculty, graduate students, and community organizations seeking to maximize the impact of academic research and expertise on public policy, social programming, and professional practice. It is supported by SSHRC and CIHR grants, and by the Office of the Vice-President Research & Innovation. [email protected] www.researchimpact.c

Taxation and the Extraction of Exhaustible Resources: Evidence From California Oil Production

Rapid increases in oil prices in 2008 led some to call for special taxes on the oil industry. Because oil is an exhaustible resource, however, the effects of excise taxes on production or on reported producer profits may be more complex than in many other markets. This paper uses well-level production data on California oil wells for the period 1977-2008, along with the rich variation in producer prices induced by federal oil taxes and pre-1980 price controls, to estimate how temporary taxes affect oil production decisions. Theory suggests that temporary taxes could lead producers to shut wells, and more generally that they create strong incentives for retiming production to minimize tax burdens. The empirical estimates suggest small estimates of extensive responses to after-tax prices, meaning that wells are rarely shut, but they also suggest substantial retiming of production for operating wells. While the estimates vary with specifications, the elasticity of oil production with respect to the after-tax price is estimated to fall between 0.208 and 0.261. The estimates are used to calibrate a simple model of the efficiency cost of tax-induced distortions relative to the no-tax optimal extraction path. These calculations suggest that a 15 percent temporary excise tax on California oil producers reduces the present value of producer surplus by between one and five percent of the no-tax surplus or between 113 and 166 percent of the government revenue raised, depending on the original life of the well and the duration of the temporary tax.MIT Department of Economics

Directed Multicut with linearly ordered terminals

Motivated by an application in network security, we investigate the following "linear" case of Directed Mutlicut. Let $G$ be a directed graph which includes some distinguished vertices $t_1, \ldots, t_k$. What is the size of the smallest edge cut which eliminates all paths from $t_i$ to $t_j$ for all $i < j$? We show that this problem is fixed-parameter tractable when parametrized in the cutset size $p$ via an algorithm running in $O(4^p p n^4)$ time.Comment: 12 pages, 1 figur

Fused filament fabrication 3D printing using low-melting alloys.

Fused Filament Fabrication (FFF) 3D printing technology has been a popular method of creating prototypes using plastics in the timeliest and most affordable manner for electronic, automotive, and biomedical applications. 3D printing of metals and alloys using FFF technology could provide low-cost alternatives and solutions to the Laser-Powder Bed Fusion Process (L-PBF) and Binder Jetting processes (BJ). In current work, low melting alloys have been used as a starting material and evaluated for FFF 3D printing using two methodologies. In the first methodology, Sn60Bi40 alloy in the form of wire was used as the feedstock for FFF extrusion and process parameters for the fabrication of 2D and 3D geometries were developed. In the second methodology, low melting alloys of Sn42Bi58, Sn60Bi40 and Sn89Sb7.5 were cast onto 3-D printed molds to fabricate metal structures. The influence of mold cooling temperature on the cast specimens of Sn60Bi40 alloy was evaluated. The fabricated specimens were evaluated for its part formability, mechanical properties, and microstructure. A prototype was fabricated using the FFF 3D printing methodology and a souvenir was cast using the FFF 3D casting methodology to show case the applicability of the FFF metal 3D printing process