A population policy for Zimbabwe Rhodesia

A journal article articulating a population policy for the then emerging nation of Zimbabwe.Few national leaders have systematically attempted to determine how many people their countries can carry at a specified level of food and energy consumption. We all know that we live in a world of finite energy supplies and where food scarcity threatens to become commonplace. We all know that nearly every developing country in the world, including Zimbabwe Rhodesia, has an unacceptably high rate of human population growth. We all know that signs of stress on the world's principal biological systems and energy resources indicate that in many places they have already reached the breaking point. Yet in spite of this, very few- national leaders have had the courage to overcome religious and political difficulties and put forward a declared Population Policy that defines an optimum population size for the country concerned that will be compatible with available resources, at the same time enhancing the quality of existence of people of all income groups

Human Service Needs in Rapidly Growing Western Communities: The Wyoming House Services Project-One Response

Human service needs in rural, western communities currently experiencing energy related growth are abundant. This paper describes and critiques a service delivery project designed to address these needs

Status of the Mast experiment

Many sophisticated mathematical control techniques for flexible structures have been devised. The basic problem is that most of them require a relatively accurate mathematical model of the system under control including the dynamics of both the structure and the control system components. Obtaining such a model for either subsystem traditionally has required great effort including a significant validation step based on test data. Because of the quantum increase in complexity over proven methods, promising techniques for the control of flexible structures must be validated in actual hardware experiments before committing to their use in actual spacecraft missions. The Mast experiment system serves as a focus for such validation. It is the first in a series of experiments under the Control of Flexible Structures (COFS) Program at the NASA Langley Research Center. The Mast experiment is a combination of ground tests, orbital flight test, and analysis of a deployable beam under the COFS program. It provides a vehicle for research in structures, structural dynamics, and control issues

Twelfth award of the Medal of the Seismological Society of America

The medal of the Seismological Society of America was established as Article XII of the Constitution and Bylaws in the 1975 annual election. The Medal recognizes outstanding contributions in Seismology and Earthquake Engineering. The twelfth award, in 1989, was made to Dr. Robert E. Wallace

Cytotoxicity and Dentin Permeability of Carbamide Peroxide and Hydrogen Peroxide Vital Bleaching Materials, in vitro

There has been recent concern about the inadvertent exposure of dentin with patent tubules as well as gingiva to bleaching systems containing 10-15% carbamide peroxide or 2-10% hydrogen peroxide for more than a few minutes. The aims of the present study were: (1) to determine the cytotoxicity of dilutions of hydrogen peroxide in cell culture; (2) to measure hydrogen peroxide diffusion from bleaching agents through dentin in vitro; and (3) to determine the risk of hydrogen peroxide-induced cytotoxicity from exposure of dentin to these vital bleaching agents. The 50% inhibitory dose (ID50) of hydrogen peroxide to succinyl dehydrogenase activity in cultured cells was found to be 0.58 mmol/L after 1 h. All bleaching materials demonstrated diffusion of hydrogen peroxide through dentin in an "in vitro pulp chamber" device. The one- and six-hour diffusates of all bleaching agents through 0.5-mm dentin exceeded the ID50 in monolayer cultures. Inhibition of succinyl dehydrogenase activity corresponded to the amount of hydrogen peroxide that can rapidly diffuse through dentin in vitro and reach concentrations which are toxic to cultured cells in less than 1 h.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66707/2/10.1177_00220345930720051501.pd

Resource Reduction in Multiplexed High-Dimensional Quantum Reed-Solomon Codes

Quantum communication technologies will play an important role in quantum information processing in the near future as we network devices together. However, their implementation is still a challenging task due to both loss and gate errors. Quantum error correction codes are one important technique to address this issue. In particular, the Quantum Reed-Solomon codes are known to be quite efficient for quantum communication tasks. The high degree of physical resources required, however, makes such a code difficult to use in practice. A recent technique called quantum multiplexing has been shown to reduce resources by using multiple degrees of freedom of a photon. In this work, we propose a method to decompose multi-controlled gates using fewer $\rm{CX}$ gates via this quantum multiplexing technique. We show that our method can significantly reduce the required number of $\rm{CX}$ gates needed in the encoding circuits for the quantum Reed-Solomon code. Our approach is also applicable to many other quantum error correction codes and quantum algorithms, including Grovers and quantum walks.Comment: 9 pages, 11 figure

Nonsteady-State Drainage from Porous Media

Drainable porosity or specific yield is a major parameter involved in all land drainage problems. Most solutions of nonsteady-state drainage problems assume abrupt drainage of the pore space as the water table is lowered. In many nonsteady-state solutions the drainable porosity is also assumed to be constant, i.e., independent of both depth to the water table and time, even though this is recognized as incorrect. Luthin and Worstellg demonstrated with a large sand-filled tank that the assumption of a fixed drainable pore space leads to incorrect solutions of drainage problems. The errors involved in this assumption are considered in detail by Childs

The effects of balance exercises on lower extremity injury prevention: a systematic review

Background: Previous systematic reviews have identified injury risk predictors of sport-related lower extremity (LE) injuries based on exercise programs. There are limited studies indicating the advantage of single-leg balance (SLB) training and its effectiveness in lowering injury rates. Research Question: Investigate which types of balance training were used in effective injury prevention programs. Methods: A systematic review utilizing the SPORTDiscus and PubMed databases. Inclusion criteria were randomized controlled trials from the last 10 years that included LE injury prevention, a balance training component and participants aged 10-30. Results: 5 studies were included in the qualitative synthesis, comprising 2,926 athletes. Three studies included SLB on firm surfaces, none significantly reduced injury. Two studies had SLB on alternating surfaces, one showed a significant reduction in injury risk. One article included SLB with psychomotor and attentional demands, which reduced injury risk. Two studies including SLB with dynamic movement showed reduced injury risk. Two studies including SLB with perturbations showed reduced injury risk and three studies showed that high adherence led to decreased injury risk. Clinical Significance: There is a dearth of research in this area, with only 5 studies within the last 10 years, so caution needs to be applied to make clinical judgments based on this systematic review. The current studies show a trend toward SLB training on firm surfaces not providing any protection against injury. However, SLB training that is incorporated with dual tasks, dynamic movement, or perturbations and that have high adherence, may give some benefit toward injury reduction

Development and Characterization of an Air-Cooled Loop Heat Pipe With a Wick in the Condenser

Thermal management of modern electronics is rapidly becoming a critical bottleneck of their computational performance. Air-cooled heat sinks offer ease and flexibility in installation and are currently the most widely used solution for cooling electronics. We report the characterization of a novel loop heat pipe (LHP) with a wick in the condenser, developed for the integration into an air-cooled heat sink. The evaporator and condenser are planar (102 mm × 102 mm footprint) and allow for potential integration of multiple, stacked condensers. The condenser wick is used to separate the liquid and vapor phases during condensation by capillary menisci and enables the use of multiple condensers with equal condensation behavior and performance. In this paper, the thermal–fluidic cycle is outlined, and the requirements to generate capillary pressure in the condenser are discussed. The LHP design to fulfill the requirements is then described, and the experimental characterization of a single-condenser version of the LHP is reported. The thermal performance was dependent on the fan speed and the volume of the working fluid; a thermal resistance of 0.177  °C/W was demonstrated at a heat load of 200 W, fan speed of 5000 rpm and fluid volume of 67 mL. When the LHP was filled with the working fluid to the proper volume, capillary pressure in the condenser was confirmed for all heat loads tested, with a maximum of 3.5 kPa at 200 W. When overfilled with the working fluid, the condenser was flooded with liquid, preventing the formation of capillary pressure and significantly increasing the LHP thermal resistance. This study provides the detailed thermal–fluidic considerations needed to generate capillary pressure in the condenser for controlling the condensation behavior and serves as the basis of developing multiple-condenser LHPs with low thermal resistance.United States. Defense Advanced Research Projects Agency (W31P4Q-09-1-0007