Can We Explain Cost Growth in Major Defense Acquisition Programs?

This question asked in this article is whether the shared intellectual property of the acquisition community includes an adequate theory of cost growth in major defense acquisition programs (MDAPs). This question is given concrete form by cost growth data for 123 MDAPs. These data are grouped into categories, which range from very small—negative, in fact—cost growth to cost growth in excess of 100%. Potential explanations for this broad range of cost growth considered are: the conventional wisdom about cost growth; a recent RAND study that closely examined cases at both ends of the distribution, along with some possible extensions of that study; and a recent model of the root causes of cost growth. The author argues that each of these falls short; in particular, it seems that the defense acquisition community at large does not have a good explanation of cost growth in the broad range of 30% to 100%.

Plant age at the time of ozone exposure affects flowering patterns, biotic interactions and reproduction of wild mustard

Exposure of plants to environmental stressors can modify their metabolism, interactions with other organisms and reproductive success. Tropospheric ozone is a source of plant stress. We investigated how an acute exposure to ozone at different times of plant development affects reproductive performance, as well as the flowering patterns and the interactions with pollinators and herbivores, of wild mustard plants. The number of open flowers was higher on plants exposed to ozone at earlier ages than on the respective controls, while plants exposed at later ages showed a tendency for decreased number of open flowers. The changes in the number of flowers provided a good explanation for the ozone-induced effects on reproductive performance and on pollinator visitation. Ozone exposure at earlier ages also led to either earlier or extended flowering periods. Moreover, ozone tended to increase herbivore abundance, with responses depending on herbivore taxa and the plant age at the time of ozone exposure. These results suggest that the effects of ozone exposure depend on the developmental stage of the plant, affecting the flowering patterns in different directions, with consequences for pollination and reproduction of annual crops and wild species.

Interpretation of Boundaries Treaties in the Light of General Principles of International Boundaries: تفسير المعاهدات الحدودية في ضوء المبادئ العامة للحدود الدولية

This paper sheds the light on the general rules for interpretation of intentional treaties, and the scope of their application on boundaries treaties. It shows the reflection of stability and finality of boundaries and subsequent conduct principles, as well as rules of equity on interpretation of boundaries treaties. This study also makes good explanation on the legal nature of boundaries treaties, and how this nature was a reason for excluding boundaries treaties from the application of fundamental change of circumstance term, and excluding boundaries treaties form application of Vienna rules of succession of state. In ends that the scope of application of general rules for interpretation of treaties is limited to adhere with general principles of international boundaries, in particular principle of stability of boundaries and principle of subsequent conduct. It explains how rules of equity can be used to change boundaries delimitated by treaties. This paper ascertains that boundaries treaties where not a subject for legal disagreement when discussing Vienna Convention of Law of treaties 1969, and Vienna Convention on Succession of States in respect of Treaties 1978, and it was agreed to exclude these treaties form the terms of these treaties.

The search for failed supernovae with the Large Binocular Telescope: a new candidate and the failed SN fraction with 11 yr of data

ABSTRACT We present updated results of the Large Binocular Telescope Search for Failed Supernovae. This search monitors luminous stars in 27 nearby galaxies with a current baseline of 11 yr of data. We re-discover the failed supernova (SN) candidate N6946-BH1 as well as a new candidate, M101-OC1. M101-OC1 is a blue supergiant that rapidly disappears in optical wavelengths with no evidence for significant obscuration by warm dust. While we consider other options, a good explanation for the fading of M101-OC1 is a failed SN, but follow-up observations are needed to confirm this. Assuming only one clearly detected failed SN, we find a failed SN fraction $f = 0.16^{+0.23}_{-0.12}$ at 90 per cent confidence. We also report on a collection of stars that show slow (∼decade), large amplitude (ΔL/L > 3) luminosity changes.

Explanation in AI systems

As AI systems come to permeate human society, there is an increasing need for such systems to explain their actions, conclusions, or decisions. This is presently fuelling a surge in interest in machine-generated explanation in the field of explainable AI. In this chapter, we examine work on explanations in areas ranging from AI to philosophy, psychology, and cognitive science. We point to different notions of explanation that are at play in these areas. We further discuss the theoretical work in philosophy and psychology on (good) explanation and its implications for the research on machine-generated explanations. Lastly, we consider the pragmatic nature of explanations and showcase its importance in the context of trust and fidelity. Throughout the chapter we suggest paths for further research on explanation in AI, psychology, philosophy, and cognitive science.

The interactive model of ethnic entrepreneurship : a case study of Pacific Mall in Markham, Ontario

Using the Interactive Model of Ethnic Entrepreneurship created by Waldinger et al. (1990), this major research paper examines the strategies employed by Chinese entrepreneurs in Toronto. Pacific Mall, an indoor shopping centre located in the outer skirt of Toronto, is selected as a case study of Chinese enclave economy to determine whether the model is reflective of reality. An in-depth examination of a set of internal and external factors is presented to explain how the opportunity structure interacts with the goup characterstics of the entrepreneurs to facilitate ethnic entrepreneurship in Pacific Mall. The findings of this paper indicates that the model generally presents a good explanation of the circumstances found in Pacific Mall; however, minor gaps remain as certain factors could not be explained by the model.

The interactive model of ethnic entrepreneurship : a case study of Pacific Mall in Markham, Ontario

Using the Interactive Model of Ethnic Entrepreneurship created by Waldinger et al. (1990), this major research paper examines the strategies employed by Chinese entrepreneurs in Toronto. Pacific Mall, an indoor shopping centre located in the outer skirt of Toronto, is selected as a case study of Chinese enclave economy to determine whether the model is reflective of reality. An in-depth examination of a set of internal and external factors is presented to explain how the opportunity structure interacts with the goup characterstics of the entrepreneurs to facilitate ethnic entrepreneurship in Pacific Mall. The findings of this paper indicates that the model generally presents a good explanation of the circumstances found in Pacific Mall; however, minor gaps remain as certain factors could not be explained by the model.

Comparative analysis of the unbinding pathways of antiviral drug Indinavir from HIV and HTLV1 proteases by Supervised Molecular Dynamics simulation

Determining the unbinding pathways of potential small molecule compounds from their target proteins is of great significance for designing efficacious treatment solutions. One of these potential compounds is the approved HIV-1 protease inhibitor, indinavir, which has a weak effect on the HTLV-1 protease. In this work, by employing SuMD method, we reconstructed the unbinding pathways of indinavir from HIV and HTLV-1 proteases in order to compare and to understand the mechanism of the unbinding, and also to discover the reasons for the lack of inhibitory activity of indinavir against the HTLV-1 protease. We achieved multiple unbinding events from both HIV and HTLV-1 proteases in which the RMSD values of indinavir reached over 4 nm. Also, we found that the mobility and the fluctuations of the flap region is higher in the HTLV-1 protease which makes the drug less stable. We realized that critically positioned aromatic residues such as Trp98/Trp98' and Phe67/Phe67' in the HTLV-1 protease can make strong pi-Stacking interactions with indinavir in the unbinding pathway which are unfavorable for the stability of indinavir in the active site. The details found in this study can make a good explanation for the lack of inhibitory activity of this drug against HTLV-1 protease. We believe the details discovered in this work can be a great assist for designing more effective and more selective inhibitors for the HTLV-1 protease.

gbt-HIPS: Explaining the Classifications of Gradient Boosted Tree Ensembles

This research presents Gradient Boosted Tree High Importance Path Snippets (gbt-HIPS), a novel, heuristic method for explaining gradient boosted tree (GBT) classification models by extracting a single classification rule (CR) from the ensemble of decision trees that make up the GBT model. This CR contains the most statistically important boundary values of the input space as antecedent terms. The CR represents a hyper-rectangle of the input space inside which the GBT model is, very reliably, classifying all instances with the same class label as the explanandum instance. In a benchmark test using nine data sets and five competing state-of-the-art methods, gbt-HIPS offered the best trade-off between coverage (0.16–0.75) and precision (0.85–0.98). Unlike competing methods, gbt-HIPS is also demonstrably guarded against under- and over-fitting. A further distinguishing feature of our method is that, unlike much prior work, our explanations also provide counterfactual detail in accordance with widely accepted recommendations for what makes a good explanation.

Ionospheric Plasma Transported into the Martian Magnetosheath

<p>How the heavy ionospheric ions escape the Martian atmosphere is still not solved. Missions such as the Mars Express (MEX) satellite have observed significant heavy ions (O<sub>2<sup>+</sup></sub> and Co<sub>2<sup>+</sup></sub>) on the night side of the terminator. The hot oxygen corona when ionized gives rise to the pickup ions but they are of lighter mass.  With the more comprehensive instrumentation on the MAVEN mission, it is clear that cold heavy ions are transported down the tail of the planet. However, there has not yet been a good explanation of how heavy ions can reach into the Martian sheath in high density concentrations. In December 2020 the MAVEN satellite was observing on the dusk side tailward of the terminator with an orbital configuration allowing the density changes and the ion compositions to be followed. In this presentation the focus is on three subsequent orbits where a channel of heavy ions with high densities reaches out into the sheath. In this presentation we will argue for different possible processes that could explain the observations.</p>