Piloted simulation of one-on-one helicopter air combat at NOE flight levels

A piloted simulation designed to examine the effects of terrain proximity and control system design on helicopter performance during one-on-one air combat maneuvering (ACM) is discussed. The NASA Ames vertical motion simulator (VMS) and the computer generated imagery (CGI) systems were modified to allow two aircraft to be independently piloted on a single CGI data base. Engagements were begun with the blue aircraft already in a tail-chase position behind the red, and also with the two aircraft originating from positions unknown to each other. Maneuvering was very aggressive and safety requirements for minimum altitude, separation, and maximum bank angles typical of flight test were not used. Results indicate that the presence of terrain features adds an order of complexiaty to the task performed over clear air ACM and that mix of attitude and rate command-type stability and control augmentation system (SCAS) design may be desirable. The simulation system design, the flight paths flown, and the tactics used were compared favorably by the evaluation pilots to actual flight test experiments

The tandem chain extension -aldol reaction of beta-keto esters

The Tandem Chain Extension-Aldol (TCEA) Reaction of beta-keto esters with aliphatic and aromatic aldehydes yields gamma-keto-beta\u27-hydroxy esters with significant syn-selectivity. A control Reformatsky reaction with a methyl 2-iodo-5,5-dimethyl-4-oxo-hexanoate 53 and methyl 2-iodo-5,5-dimethylhexanoate 65 indicates that the presence of a gamma-keto-functionality in the zinc-organometallic intermediate in the TCEA reactions is key to the syn-selectivity that is observed. The gamma-keto-functionality, through complexation to zinc, may direct the bias of the reaction toward a transition state that results in the syn-product. An investigation of the zinc-organometallic intermediate with Nuclear Magnetic Resonance Spectroscopy has supported the theory that the intermediate\u27s gamma-keto-group is coordinated to zinc-species on the reaction mixture. Use of protected alpha-hydroxyacetaldehydes in the TCEA reaction results in an erosion in the syn-selectivity of the TCEA reaction. A study, in which the steric bulk of the hydroxyacetaldehyde\u27s protecting group was varied, has indicated that the erosion in syn-selectivity is likely due to complexation of the aldehydes hydroxy-functionality to zinc in the transition state of the TCEA reaction. Finally, in an attempt to develop an approach toward the synthesis of CJ-12,954 114a, the TCEA reaction has been successfully applied to the synthesis of spiroketal units, via the generation of dihydroxy-keto synthons

The Cotton Plantation South since the Civil War

"The plantation," writes Charles Aiken, "is among the most misunderstood institutions of American history. The demise of the plantation has been pronounced many times, but the large industrial farms survive as significant parts of, not just the South's, but the nation's agriculture."In this sweeping historical and geographical account, Aiken traces the development of the Southern cotton plantation since the Civil War—from the emergence of tenancy after 1865, through its decline during the Depression, to the post-World War Two development of the large industrial farm. Tracing the geographical changes in plantation agriculture and the plantation regions after 1865, Aiken shows how the altered landscape of the South has led many to the false conclusion that the plantation has vanished. In fact, he explains, while certain regions of the South have reverted to other uses, the cotton plantation survives in a form that is, in many ways, remarkably similar to that of its antebellum predecessors. Aiken also describes the evolving relationship of African-Americans to the cotton plantation during the thirteen decades of economic, social, and political changes from Reconstruction through the War on Poverty—including the impact of alterations in plantation agriculture and the mass migration of Southern blacks to the urban North during the twentieth century. Richly illustrated with more than 130 maps and photographs (many original and many from FSA photographers), The Cotton Plantation South is a vivid and colorful account of landscape, geography, race, politics, and civil rights as they relate to one of America's most enduring and familiar institutions

Pathways to Online Hate: Behavioural, Technical, Economic, Legal, Political & Ethical Analysis.

The Alfred Landecker Foundation seeks to create a safer digital space for all. The work of the Foundation helps to develop research, convene stakeholders to share valuable insights, and support entities that combat online harms, specifically online hate, extremism, and disinformation. Overall, the Foundation seeks to reduce hate and harm tangibly and measurably in the digital space by using its resources in the most impactful way. It also aims to assist in building an ecosystem that can prevent, minimise, and mitigate online harms while at the same time preserving open societies and healthy democracies. A non-exhaustive literature review was undertaken to explore the main facets of harm and hate speech in the evolving online landscape and to analyse behavioural, technical, economic, legal, political and ethical drivers; key findings are detailed in this report

Open-mindedness can decrease persuasion amongst adolescents: The role of self-affirmation

Objectives Self-affirmation (e.g., by reflecting on important personal values) has been found to promote more open-minded appraisal of threatening health messages in at-risk adults. However, it is unclear how self-affirmation affects adolescents and whether it has differential effects on the impact of these messages amongst those at relatively lower and higher risk. The current study explored moderation by risk. Design Participants were randomly assigned to either a self-affirmation or a control condition before receiving a health message concerning physical activity. Methods Older adolescents (N = 125) completed a self-affirmation or control writing task before reading about the health consequences of not meeting recommendations to be physically active for at least 60 min daily. Most of the sample did not achieve these levels of activity (98%, N = 123). Consequently, the message informed these participants that – unless they changed their behaviour – they would be at higher risk of heart disease. Participants completed measures of responses to the message and behaviour-specific cognitions (e.g., self-efficacy) for meeting the recommendations. Results For relatively inactive participants, self-affirmation was associated with increased persuasion. However, for those who were moderately active (but not meeting recommendations), those in the self-affirmation condition were less persuaded by the message. Conclusions Whilst self-affirmation can increase message acceptance, there are circumstances when the open-mindedness it induces may decrease persuasion. The evidence provided in this study suggests that caution may be needed when recommendations are challenging and it could be considered reasonable to be sceptical about the need to change behaviour

Alternate-fueled transport aircraft possibilities

The paper is organized to describe: (1) NASA's cryogenically fueled aircraft program; (2) LH2 subsonic and supersonic transport design possibilities (3) the fuel system and ground side problems associated with LH2 distribution; (4) a comparison of LCH4 with LH2; (5) the design possibilities for LCH4 fueled aircraft; and (6) a summary of where NASA's cryogenically fueled programs are headed

Standard nomenclature for airspeeds with tables and charts for use in calculation of airspeed

Symbols and definition of various airspeed terms that have been adopted as standard by the NACA subcommittee on aircraft structural design are presented. The equations, charts, and tables required in the evaluation of true airspeed, calibrated airspeed, equivalent airspeed, impact and dynamic pressures, and Mach and Reynolds numbers have been compiled. Tables of the standard atmosphere to an altitude of 65,000 feet and a tentative extension to an altitude of 100,000 feet are given along with the basic equations and constants on which both the standard atmosphere and the tentative extension are based