Biofuel Boom, Aquifer Doom?

Resource /Energy Economics and Policy,

Factual Causation: The Missing Link in Hydraulic Fracture—Groundwater Contamination Litigation

A speech-based material that early can assess a child's hearing is needed to provide an indication of a hearing impaired child's language development. Being able to identify and discriminate between different sounds is a requirement for interpreting speech. Hearing assessments that examine speech perception can therefore, unlike, for example, pure tone audiometry, examine a hearing impaired child's perceptual language skills and provide a basis for intervention. The purpose of this work is to evaluate a new auditory material on 3-year-old children. The auditory material is based on the Ling-6-sounds and the main question was which of the sounds in the test were adequate for test of discrimination. Furthermore, it was investigated how the test works with children aged 3:0–3:11 years and how age and gender affect the result. Twenty-four children aged 3:0–3:11 years were tested using a computer based test. The goal  for the child was to discriminate between pairs of sounds and react to an odd pair. Several instruction techniques were tested by two different test administrators. The results of the tests indicated that equal pairs of sounds (/do/-/do/, /s/-/s/) gave more correct responses. The test section where only two different pairs were used generated more adequate responses than the test section with six different pairs. Differences in age influenced the outcome more than sex and different instructions. There is also a need for improved instructions and sounds. Generally, children became more involved in the test when given instructions that were short and direct

Idea vs. Icon: Two Competitions

The United States is blessed with a natural landscape that is both expansive and richly varied. Our recent attitude toward the relationship between the built and natural environment, however, has been at best a naively romantic one and at worst an instrument of private exploitation..

Compatibility of potential reinforcing ceramics with Ni and Fe aluminides

There is a great deal of interest in the possible utilization of intermetallic compounds in advanced high temperature gas turbine engines. These compounds exhibit a variety of promising properties, including reasonable strength, high melting points, relatively low densities, and good corrosion resistance. However, in general, they also show limited ductilities and toughness, and less than optimum creep strengths at elevated temperatures. In addition, in applications involving advanced gas turbine engines, it is often necessary for candidate materials to have large elastic moduli. The present study is part of a program whose objective is to identify a high temperature fiber reinforced composite. The approach adopted was to fabricate laboratory samples of the combinations of materials considered by Misra, in order to determine the extent to which the thermodynamic calculations can predict phase stability. As many of the ceramic phases considered are not currently available in fiber form, they were added as particulates to the alloy matrices. The ways in which the materials were produced and evaluated are described

Where Do U.S. Immigrants Come From, and Why?

The United States has experienced rising immigration levels and changing source since the 1950s. The changes in source have been attributed to the 1965 Amendments to the Immigration Act that abolished country-quotas and replaced them with a system that emphasized family reunification. Some believed that the Amendments would not change the 'traditional' sources of US immigrants. Given this view, it seems all the more remarkable that the sources of immigration changed so dramatically. This paper isolates the economic and demographic fundamentals that determined immigration rates by source from 1971 to 1998 -- income, education, demographic composition and inequality. The paper also allows for persistence - big US foreign-born stocks implying a strong 'friends and neighbors' pull on current immigrant flows. Specific policy variables are included which are derived directly from the quotas allocated to different visa categories. Parameter estimates from the panel data are then used to implement counterfactual simulations that serve to isolate the effects of immigration policy as well as source-country economic and demographic conditions.

Advanced bale weighing with integrated mass yield system for large square balers

This research was focused on development of a large square baler mass measurement system. The mass measurement system was designed to provide estimations of mass yield, mass flow, individual flake weights, and bale weights. The developed mass measurement system was evaluated at the same level as the measured ground truth which was defined to be on a bale basis. The mass measurement system utilized experimental force measuring sensors located in the pre-compression chamber to capture the forces associated with crop mass in the pre-compression chamber. Force information coupled with production baler sensor information and geographical information were combined to create estimation of mass flow and mass yield. The developed mass measurement system was evaluated against production scale systems. The performance of the developed mass measurement system was not significantly different at a 95% confidence level when compared to current production bale scale systems and successfully demonstrated mass yield estimations

Noise attenuation and communication enhancement characteristics of the USCG boat crew communication system

The US Coast Guard is prototyping a new small boat communication system which consists of the MSA Sordin Supreme Pro headset in combination with a wireless communications system. The MSA Sordin headset receives wireless communications input independently from an amplitude-sensitive sound transmission feature which amplifies ambient noise in certain frequency ranges. The purpose of this study was to determine the extent to which the communication system improves speech intelligibility in noise and to measure the noise reducing capabilities of the headset with the amplification feature activated and with it turned off. Overall noise reduction was calculated based on four different noise spectrums to compare actual noise reduction to the manufacturer advertised Noise Reduction Rating (NRR). Additionally, clamp force was measured to determine its relationship with noise reduction. This study found that the communication system, consisting of wireless communications and the activated headset amplification feature, drastically improved verbal communications when compared to the case of the headset donned but wireless communication disconnected and headset amplification off (88% vs 44% intelligibility score in 90 dBA background noise; 82% vs negligible intelligibility in 100 dBA background noise). The MSA Sordin headset amplification feature had a profound effect on the hearing protector\u27s noise reducing capability. When it was activated, noise reduction was dramatically lower in all frequencies above 315 Hz. This resulted in lower overall noise reduction when this feature was on. Mean overall noise reduction values ranged from 11.2 to 27 dBA with the amplification feature turned off and 6.7 to 0.2 dBA with the amplification feature activated. The difference was least in low frequency dominant noise (11.2 vs 6.7 dBA) and greatest in high frequency dominant noise (27 vs 0.2 dBA). The low frequency dominant spectrum used in this study was recorded onboard an operational USCG 47\u27 Motor Life Boat, the system\u27s intended operating environment. In this intended environment, the calculated overall noise reduction was less than the manufacturer advertised rating of 18 dB (study values; 11.2 dBA without amplification, 6.7 dBA with amplification). A weak positive correlation was found between clamp force and noise reduction but the association was not statistically significant, meaning that clamp force was not the reason for the noise reduction performance of the MSA Sordin headset