Propulsion by Reaction

This report concerns propulsion by means of rockets. The author concerns himself mainly with efficiency of propulsion and he defines and mathematically expresses those efficiencies

On the roles of vertical velocity and eddy conductivity in maintaining a thermocline

Steady-state solutions of the vertical heat-balance equation have been obtained for various assumed vertical profiles of the vertical component of velocity and eddy conductivity. Relationships have been found for the depth and the thickness of the thermocline in terms of parameters that characterize the vertical velocity and eddy conductivity. Two of the solutions agree with observations in regions having respectively divergent and convergent Ekman mass transport

A method and medium for the electrical detection of Listeria spp. from food

The development of a liquid medium for the detection of Listeria spp. by capacitance monitoring of food samples previously enriched in UVM 1 broth is described. Rapid growth of Listeria monocytogenes was shown to occur in liquid media with selectivity based on antibiotics found in Oxford agar. The final capacitance medium contained higher concentrations of the Oxford selective agents than Oxford agar and did not require the esculin/ferric ammonium citrate reaction to be observed. The medium relied upon the ability of Listeria spp. to induce a greater than 30% change in capacitance within 30 h. When run in parallel with the Listeria spp. test samples of a large food company, the method gave far fewer false-positive results than Fraser broth

Theoretical Investigations on the Efficiency and the Conditions for the Realization of Jet Engines

Contents: Preliminary notes on the efficiency of propulsion systems; Part I: Propulsion systems with direct axial reaction rockets and rockets with thrust augmentation; Part II: Helicoidal reaction propulsion systems; Appendix I: Steady flow of viscous gases; Appendix II: On the theory of viscous fluids in nozzles; and Appendix III: On the thrusts augmenters, and particularly of gas augmenter

Dire necessity or mere opportunity? Recurring commercialization of peat exploited from raised bog commons in the Low Countries

Traditional commons scholarship, and in particular common-pool resource (CPR) theory, argues that historical commons institutions were autonomous, little influenced by either markets or states, and that commercialisation and sustainable collective use of common-pool resources were incompatible. This paper examines to what extent this view holds true. It does so by analysing historical sources on two local cases of peat commercialisation from raised bog commons in the early modern Low Countries: the Bakelse gemeint in the Peel region, and the commune de Xhoffraix in the Hautes Fagnes. The significance of peat commercialisation from commons was notably in its permanence, recurrence, and/or regional outreach, rather than in its limited volume share in total peat exploitation. Dire financial need of communities with high debts and taxes can partly explain the motives for peat commercialisation. Viewed over the longer term mere opportunity to gain some money was a plausible additional motive. In addition, stately institutions could influentially interfere in commons management in times of (internal) conflict. Sources indicate a pragmatic attitude towards peat commercialisation by these institutions, possibly to foster social peace and local prosperity in times of resource contestation and economic hardship. This study adds a novel intermediate category of peat exploitation to the traditional binary subdivision in domestic peat extraction from commons versus large-scale commercial exploitation of privatised bogs. We demonstrate that long-term use of common-pool resources could go together with a moderate degree of commercialisation. Rather than being fully autonomous, commons institutions were - structurally or at times of internal conflict - clearly impacted by markets, notions of private property, and stately institutions