Estimating the causal effect of a time-varying treatment on time-to-event using structural nested failure time models

In this paper we review an approach to estimating the causal effect of a time-varying treatment on time to some event of interest. This approach is designed for the situation where the treatment may have been repeatedly adapted to patient characteristics, which themselves may also be time-dependent. In this situation the effect of the treatment cannot simply be estimated by conditioning on the patient characteristics, as these may themselves be indicators of the treatment effect. This so-called time-dependent confounding is typical in observational studies. We discuss a new class of failure time models, structural nested failure time models, which can be used to estimate the causal effect of a time-varying treatment, and present methods for estimating and testing the parameters of these models

Longitudinal aerodynamic characteristics of an elliptical body with a horizontal tail at Mach numbers from 2.3 to 4.63

Longitudinal aerodynamic characteristics of a configuration consisting of an elliptical body with an in plane horizontal tail were investigated. The tests were conducted at Mach numbers of 2.3, 2.96, 4.0, and 4.63. In some cases, the configuration with negative tail deflections yielded higher values of maximum lift drag ratio than did the configuration with an undeflected tail. This was due to body upwash acting on the tail and producing an additional lift increment with essentially no drag penalty. Linear theory methods used to estimate some of the longitudinal aerodynamic characteristics of the model yielded results which compared well with experimental data for all Mach numbers in this investigation and for both small angles of attack and larger angles of attack where nonlinear (vortex) flow phenomena were present

Supersonic wings with significant leading-edge thrust at cruise

Experimental/theoretical correlations are presented which show that significant levels of leading edge thrust are possible at supersonic speeds for certain planforms which match the theoretical thrust distribution potential with the supporting airfoil geometry. The analytical process employed spanwise distribution of both it and/or that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated

Aerodynamic characteristics at Mach numbers of 1.5, 1.8, and 2.0 of a blended wing-body configuration with and without integral canards

An exploratory, experimental, and theoretical investigation was made of a cambered, twisted, and blended wing-body concept with and without integral canard surfaces. Theoretical calculations of the static longitudinal and lateral aerodynamic characteristics of the wing-body configurations were compared with the characteristics obtained from tests of a model in the Langley Unitary Plan wind tunnel. Mach numbers of 1.5, 1.8, and 2.0 and a Reynolds number per meter of 6.56 million were used in the calculations and tests. Overall results suggest that planform selection is extremely important and that the supplemental application of new calculation techniques should provide a process for the design of supersonic wings in which spanwise distribution of upwash and leading-edge thrust might be rationally controlled and exploited

Supersonic aircraft Patent

Design of supersonic aircraft with novel fixed, swept wing planfor

Effect of emerging technology on a convertible, business/interceptor, supersonic-cruise jet

This study was initiated to assess the feasibility of an eight-passenger, supersonic-cruise long range business jet aircraft that could be converted into a military missile carrying interceptor. The baseline passenger version has a flight crew of two with cabin space for four rows of two passenger seats plus baggage and lavatory room in the aft cabin. The ramp weight is 61,600 pounds with an internal fuel capacity of 30,904 pounds. Utilizing an improved version of a current technology low-bypass ratio turbofan engine, range is 3,622 nautical miles at Mach 2.0 cruise and standard day operating conditions. Balanced field takeoff distance is 6,600 feet and landing distance is 5,170 feet at 44,737 pounds. The passenger section from aft of the flight crew station to the aft pressure bulkhead in the cabin was modified for the interceptor version. Bomb bay type doors were added and volume is sufficient for four advanced air-to-air missiles mounted on a rotary launcher. Missile volume was based on a Phoenix type missile with a weight of 910 pounds per missile for a total payload weight of 3,640 pounds. Structural and equipment weights were adjusted and result in a ramp weight of 63,246 pounds with a fuel load of 30,938 pounds. Based on a typical intercept mission flight profile, the resulting radius is 1,609 nautical miles at a cruise Mach number of 2.0

Application of near-term technology to a Mach 2.0 variable-sweep-wing, supersonic-cruise executive jet

The impact of variable sweep wing technology with relaxed static stability requirements on a supersonic-cruise executive jet with transatlantic range was assessed. The baseline vehicle utilized modified, current-technology engines and titanium structures produced with superplastic forming and diffusion bonding; this vehicle meets study requirements for both supersonic-cruise and low-speed characteristics. The baseline concept has a ramp weight of 64,500 pounds with a crew of two and eight passengers. Its Mach 2.0 cruise range is nearly 3,500 nautical miles; its Mach 0.9 cruise range is over 5,000 nautical miles. Takeoff, landing, and balanced field length requirements were calculated for a composite variant and are all less than 5,000 feet

Is high self-esteem beneficial? Revisiting a classic question

Debates about the benefits of self-esteem have persisted for decades, both in the scientific literature and in the popular press. Although many researchers and lay people have argued that high self-esteem helps individuals adapt to and succeed in a variety of life domains, there is widespread skepticism about this claim. The present article takes a new look at the voluminous body of research (including several meta-analyses) examining the consequences of self-esteem for several important life domains: relationships, school, work, mental health, physical health, and antisocial behavior. Overall, the findings suggest that self-esteem is beneficial in all these domains, and that these benefits hold across age, gender, and race/ethnicity, and controlling for prior levels of the predicted outcomes and potential third variable confounds. The meta-analytic estimates of self-esteem effects (which average .10 across domains) are comparable in size to estimates for other hypothesized causal factors such as self-efficacy, positive emotionality, attachment security, and growth mindset, and larger than some generally accepted pharmaceutical interventions. Discussion focuses on several issues that are critical for evaluating the findings, including the strength of the evidence for making causal inferences, the magnitude of the effects, the importance of distinguishing between self-esteem and narcissism, and the generalizability of the results. In summary, the present findings support theoretical conceptions of self-esteem as an adaptive trait that has wide-ranging influences on healthy adjustment and adaptation, and suggest that interventions aimed at boosting self-esteem might, if properly designed and implemented, benefit individuals and society as a whole. (PsycInfo Database Record (c) 2022 APA, all rights reserved)

The benefits of self-esteem: Reply to Krueger et al. (2022) and Brummelman (2022)

Krueger et al. (2022) argue that our review (Orth & Robins, 2022) finds benefits of self-esteem primarily for subjective outcomes and largely fails to demonstrate any "objective" benefits. We disagree with this portrayal of the findings and highlight research that provides evidence for the benefits of self-esteem using objective measures. We also address Krueger et al.'s claim that positivity bias in self-reports can account for the effects of self-esteem on subjectively assessed life outcomes, and explain how the statistical analyses used to document these effects substantially control for this bias. We maintain that there is now a large body of evidence from meta-analyses and large-scale longitudinal studies demonstrating that high self-esteem has adaptive consequences for social relationships, school, work, mental health, physical health, and antisocial behavior. Brummelman (2022) presents a compelling theoretical framework that can guide the design of interventions to improve children's self-esteem. We agree with his concerns about the need for randomized controlled trials to evaluate the efficacy of self-esteem interventions and the importance of ensuring that children's self-esteem can be raised without causing them to become narcissistic. The research reviewed in our article indicates that high self-esteem is adaptive for children, adolescents, and adults, suggesting that well-designed and effective self-esteem interventions might be beneficial for individuals of all ages. (PsycInfo Database Record (c) 2022 APA, all rights reserved)