REDUCING SHIP EMISSIONS: A REVIEW OF POTENTIAL PRACTICAL IMPROVEMENTS IN THE PROPULSIVE EFFICIENCY OF FUTURE SHIPS

Environmental issues such as the emission of greenhouse gases, pollution, wash and noise are having an increasing impact on the design and operation of ships. These environmental issues together with economic factors, such as rising fuel costs, all ultimately lead to the need to minimise ship propulsive power. Various methods and devices for reducing propulsive power are reviewed and discussed. The most favourable methods, from a feasible and practical point of view, are identified and quantified. It is found that potential reductions in the resistance of existing good hull forms are relatively small, but optimising hull-propeller-rudder interaction offers very promising prospects for improvement. The biggest potential savings in power arise from optimised operational strategies such as the use of optimum trim, speed and weather routeing. Potential conflicts of interest when considering both economic and environmental requirements are investigated and discussed. Suitable design methodologies and procedures, taking into account economic and environmental factors, are suggested for the design of future ships.

Family Wealth and the Class Ceiling: The Propulsive Power of The Bank of Mum and Dad

In this article we demonstrate that those from working-class backgrounds face a powerful ‘class ceiling’ in elite occupations. Examining how class origin shapes economic returns in the Norwegian upper class (3.8% of the population), we first find that the income advantage enjoyed by those from privileged backgrounds increases sharply as they ascend the income distribution in both elite business and cultural fields. Second, we show that those from economically upper-class backgrounds enjoy the highest pay advantage in all upper-class destinations. Finally, we demonstrate the profound propulsive power provided by parental wealth. Our results indicate that this is the most important single driver of the class-origin income gap in virtually every area of the Norwegian upper class. These findings move forward an emerging literature on class-origin pay gaps beyond mean estimates to reveal the distinct ‘pay-off’ to class privilege in the very highest income-earning positions.

The Decline and Persistence of the Old Boy: Private Schools and Elite Recruitment 1897 to 2016

We draw on 120 years of biographical data ( N = 120,764) contained within Who’s Who—a unique catalogue of the British elite—to explore the changing relationship between elite schools and elite recruitment. We find that the propulsive power of Britain’s public schools has diminished significantly over time. This is driven in part by the wane of military and religious elites, and the rise of women in the labor force. However, the most dramatic declines followed key educational reforms that increased access to the credentials needed to access elite trajectories, while also standardizing and differentiating them. Notwithstanding these changes, public schools remain extraordinarily powerful channels of elite formation. Even today, the alumni of the nine Clarendon schools are 94 times more likely to reach the British elite than are those who attended any other school. Alumni of elite schools also retain a striking capacity to enter the elite even without passing through other prestigious institutions, such as Oxford, Cambridge, or private members clubs. Our analysis not only points to the dogged persistence of the “old boy,” but also underlines the theoretical importance of reviving and refining the study of elite recruitment.

The Decline and Persistence of the Old Boy: Private Schools and Elite Recruitment 1897 to 2016

We draw on 120 years of biographical data (N = 120,764) contained within Who’s Who—a unique catalogue of the British elite—to explore the changing relationship between elite schools and elite recruitment. We find that the propulsive power of Britain’s public schools has diminished significantly over time. This is driven in part by the wane of military and religious elites, and the rise of women in the labor force. However, the most dramatic declines followed key educational reforms that increased access to the credentials needed to access elite trajectories, while also standardizing and differentiating them. Notwithstanding these changes, public schools remain extraordinarily powerful channels of elite formation. Even today, the alumni of the nine Clarendon schools are 94 times more likely to reach the British elite than are those who attended any other school. Alumni of elite schools also retain a striking capacity to enter the elite even without passing through other prestigious institutions, such as Oxford, Cambridge, or private members clubs. Our analysis not only points to the dogged persistence of the “old boy,” but also underlines the theoretical importance of reviving and refining the study of elite recruitment.

Mechanical Differences between Barbell and Body Optimum Power Loads in the Jump Squat Exercise

This study compared the values of bar-peak force (PFBar) and power (PPBar), body-peak force (PFBody) and power (PPBody) and bar-mean propulsive power (MPPBar) in different jump-squat (JS) conditions: unloaded condition (UC); bar-loaded condition (BLC) and optimum bar-MPP condition (OBC). Twenty-five soccer players performed the JS using a bar with negligible mass (UC), using the Smith-machine bar (BLC) and using the load capable of maximizing the bar-MPP (OBC). The PFBody was significantly higher in the UC (2847.9 ± 489.1 N) than in the OBC (2655.4 ± 444.3 N). The UC presented greater PPBody (3775.9 ± 631.5 W) than the BLC (3359.7 ± 664.3 W) and OBC (3357.8 ± 625.3 W). The OBC presented higher values of PFBar, PPBar and MPPBar (676.2 ± 109.4 W) than the BLC (MPPBar = 425.8 ± 53.7 W) (all p < 0.05). In the OBC (compared to the UC), the body peak-power presented a reduction of ≈ 11%, while generating bar-power output from ≈ 59 to 73% higher than the BLC. While the fact that the body-peak power is maximized in the UC denotes a mechanical phenomenon, the bar-optimum load represents an intensity at which both components of the power equation (force and velocity) are optimized. This has important implications for sports training.