The Phosphoramidase Competency of Prototypical Phosphatase Catalytic Motifs

The discovery that phosphorylation of proteins occurs on nitrogen by particular kinases raises the question of whether a separate class of phosphoramidases also exists, or if known phosphatases carry out the hydrolysis of phosphoramidates. The phosphoramidase activity of a number of phosphatases with different catalytic motifs was studied using the substrates N-phenylphosphoramidate (N-phPAM) and phosphoryl imidazole (PIm). The phosphatases assayed were: the protein tyrosine phosphatase YopH; alkaline phosphatase; the dual-specificity phosphatase VHR; prostatic acid phosphatase, PAcP; PHPT1, the only known phosphohistidine phosphatase; and, the serine/threonine phosphatases Lambda PP and PP1. The catalytic efficiencies, kcat/KM (s-1M-1), were compared for the respective phosphoramidase and phosphatase activities for each enzyme. Ratios of catalytic efficiencies (kcat/KM)/(kcat/KM) of pNPP over PIm are: YopH - 27; AP - 4.1; VHR - 0.22; PAcP - 1.6; AP - 0.51; and PHPT1 - 0.00007. Lambda PP catalyzed hydrolysis of PIm, although kinetic constants could not be obtained. PP1 exhibited no phosphoramidase activity. The results show that most phosphatase catalytic motifs display catalytic promiscuity by cleaving both phosphoesters and phosphoramidates, but with a pronounced preference for one substrate type versus the other

Topology Optimization of Engine Exhaust-Washed Structures

Aircraft structure subjected to elevated temperature and acoustic loading present a challenging design environment. Thermal stress in a structural component has typically been alleviated by allowing thermal expansion. However, very little work has been done which directly addresses the situation where such a prescription is not possible. When a structural component has failed due to thermally-induced tensile stresses, the answer to the question of how best to stiffen the structure is far from trivial. In this work, we demonstrate that conventional stiffening techniques, for example, those which add material to the thickness of a failing panel, may actually increase the rate of damage as well as increasing load into sub- and surrounding structure. The typical compliance minimization topology optimization formulation is applied to a thermally-loaded panel resulting in extremely non-optimal configurations. To generate successful thermal stress designs where the objectives are to lower the tensile stresses while simultaneously limiting the amount of additional load into sub- and surrounding structures, a well-known characteristic of topology optimization for a single-load case mechanical loading is exploited which by construction limits additional load into surrounding structure. Acoustic loading is also a major concern as exhaust gases with random frequency content impinge on aircraft structure in the vicinity of the engines. An evolutionary structural optimization algorithm is developed which addresses both the maximum von-Mises stress and minimum natural frequency for a generic thermal protection system. The similarities between the two approaches are demonstrated

Cylindrical contact homology of 3-dimensional Brieskorn manifolds

Cylindrical contact homology is a comparatively simple incarnation of symplectic field theory whose existence and invariance under suitable hypotheses was recently established by Hutchings and Nelson. We study this invariant for a general Brieskorn 3-manifold $\Sigma(a_1,\ldots, a_n)$, and give a complete description of the cylindrical contact homology for this 3-manifold equipped with its natural contact structure, for any $a_j$ satisfying $\frac{1}{a_1} + \cdots + \frac{1}{a_n} < n-2$

Utility Cost of Formal Privacy for Releasing National Employer-Employee Statistics

National statistical agencies around the world publish tabular summaries based on combined employer-employee (ER-EE) data. The privacy of both individuals and business establishments that feature in these data are protected by law in most countries. These data are currently released using a variety of statistical disclosure limitation (SDL) techniques that do not reveal the exact characteristics of particular employers and employees, but lack provable privacy guarantees limiting inferential disclosures. In this work, we present novel algorithms for releasing tabular summaries of linked ER-EE data with formal, provable guarantees of privacy. We show that state-of-the-art differentially private algorithms add too much noise for the output to be useful. Instead, we identify the privacy requirements mandated by current interpretations of the relevant laws, and formalize them using the Pufferfish framework. We then develop new privacy definitions that are customized to ER-EE data and satisfy the statutory privacy requirements. We implement the experiments in this paper on production data gathered by the U.S. Census Bureau. An empirical evaluation of utility for these data shows that for reasonable values of the privacy-loss parameter ϵ≥1, the additive error introduced by our provably private algorithms is comparable, and in some cases better, than the error introduced by existing SDL techniques that have no provable privacy guarantees. For some complex queries currently published, however, our algorithms do not have utility comparable to the existing traditiona

The angular dependence of spin-orbit torque in monolayer Fe3GeTe2Fe_3GeTe_2

In ferromagnetic systems lacking inversion symmetry, an applied electric field can control the ferromagnetic order parameters through the spin-orbit torque. The prototypical example is a bilayer heterostructure composed of a ferromagnet and a heavy metal that acts as a spin current source. In addition to such bilayers, spin-orbit coupling can mediate spin-orbit torques in ferromagnets that lack bulk inversion symmetry. A recently discovered example is the two-dimensional monolayer ferromagnet $Fe_3GeTe_2$. In this work, we use first-principles calculations to study the spin-orbit torque and ensuing magnetic dynamics in this material. By expanding the torque versus magnetization direction as a series of vector spherical harmonics, we find that higher order terms (up to $\ell=4$) are significant and play important roles in the magnetic dynamics. They give rise to deterministic, magnetic field-free electrical switching of perpendicular magnetization.Comment: 8 pages (3 pages appendix), 7 figure

Control of Information Systems Development: Investigating the Relationship between Control and Performance

Organizational control, defined as efforts to increase the chances that employees of an organization work toward achieving organizational goals, is believed to have positive effects on performance. However, few studies have tested this assumption. This research draws on theories of control and coordination to investigate the relationship between control and information systems (IS) development performance.It consists of analyses of two research models, one at the individual level of analysis, and the other at the team level of analysis. The individual-level model investigates how control affects individual effort toward task and individual coordination success, and proposes that these relationships are moderated by controlees' perceptions of how effectively a controller can monitor their work behaviors and outcomes. The team-level model investigates two mediators through which control may affect IS development performance: team effort toward task, and team coordination success. A field survey was conducted, and completed matched survey responses from 106 managers and team members involved in 36 different IS development projects were used to test the hypotheses.The results suggest that control does have a positive relationship with effort toward task and coordination success. Specifically, clan control was positively associated with coordination success at the individual and team levels, and with team effort toward task. Outcome control was positively associated with individual effort toward task. In addition, the relationship between outcome control and individual effort toward task was moderated by team member perceptions of the difficulty of observing outcomes. At high levels of difficulty of observing outcomes, high levels of outcome control resulted in higher effort than at low levels of difficulty of observing outcomes.Control was also positively related to performance outcomes. Behavior control was associated with reduced overruns of resources such as time, budget, and systems and programming effort. Outcome control was positively associated with product performance, which represents the quality, ease-of-use, and functionality of the system developed or enhanced by the project. Clan control was associated with both improved product performance and reduced resource overruns.No support was found for mediation of the effects of control on performance by effort toward task or coordination success

National Emission Standards for Hazardous Air Pollutants?Calendar Year 2011 INL Report for Radionuclides (2012)

This report documents the calendar year 2011 radionuclide air emissions and resulting effective dose equivalent to the maximally exposed individual member of the public from operations at the Department of Energy's Idaho National Laboratory Site. This report was prepared in accordance with the Code of Federal Regulations, Title 40, 'Protection of the Environment,' Part 61, 'National Emission Standards for Hazardous Air Pollutants,' Subpart H, 'National Emission Standards for Emissions of Radionuclides Other than Radon from Department of Energy Facilities.' The effective dose equivalent to the maximally exposed individual member of the public was 4.58E-02 mrem per year, 0.46 percent of the 10 mrem standard

A Spreadsheet Simulation to Teach Concepts of Sampling Distributions and the Central Limit Theorem

This paper presents an interactive spreadsheet simulation model that may be used to help students understand the concept of sampling distributions and the implications of the central limit theorem for sampling distributions. The spreadsheet model simulates an approximation to a sampling distribution by taking 1,000 random samples from a population, calculating the mean of each sample, and then using percentage polygons to display the distribution of the sample means compared to the distribution of the population. A normal probability plot of the sample means is also created as a second tool for understanding the distribution of the sample means. The user may vary the size of the samples taken, and then observe the effects of sample size on the range and shape of the approximated sampling distribution. The spreadsheet model is built without macros or VBA programming, using only standard formulas and tools. The instructor may choose to build the model with students, or simply present it to them and lead them in experimenting with it, depending on the needs of the class