The origin of fine scale acoustic stratigraphy in deep-sea carbonates

In this paper we investigate the origin and geologic significance of the closely spaced high-frequency subbottom acoustic reflectors characteristic of pelagic carbonates. A detailed survey was conducted of a small area in the equatorial Pacific with the Marine Physical Laboratory\u27s Deep-Tow instrument package, providing high-resolution 4-kHz profiles and precise positioning of core samples. The cores were sampled at closely spaced intervals for sound velocity and saturated bulk density. Acoustic impedances were calculated, and a reflection coefficient log determined for the upper 10 m of the sediment column. The reflection coefficient log revealed no interfaces with large reflection coefficients that correlated with the reflectors seen on the Deep-Tow 4-kHz seismic profile. The calculated reflection coefficients were very low (typically 10−3–10−5) and varied about a wavelength that was on the order of the wavelength of the 4-kHz pulse, implying that interference plays a role in the composition of the seismic record. Convolving the outgoing 4-kHz pulse with the reflection coefficient log generated a synthetic seismogram that very closely resembled the 4-kHz reflection profile. Varying the frequency of the outgoing pulse changed the amplitude and position of the reflectors seen on the synthetic seismograms. Thus we conclude that the reflectors seen on the 4-kHz seismic profile were not caused by discrete geologic horizons but rather are the result of the interference of many small layers

An infrared reflectance study of low albedo surface constituents

Observational testing of the idea that the distribution of water is the key to understanding the volatile content of the asteroid belt relies on the exploration of the 3 micron absorption feature in hydrated silicates - the only diagnostic spectral band evident in the dark, volatile rich CI and CM meteorites. The existence of the band has demonstrated the presence of hydrated silicates on asteroids. An example of this feature is shown in the spectrum of the CI meteorite Orgueil. The feature is characterized by a sharp reflectance drop at 2.7 microns, due to structural OH, and by an absorption due to H2O that decreases slowly out to about 3.5 microns. In their present observational program, researchers are expanding their observational program to include other low-albedo classes of asteroids - asteroids that range primarily from the middle and outer asteroid belt (greater than 2.5 AU) to the Trojan region at 5.2 AU. Preliminary results indicate that the outer belt and Trojan asteroids do not show feature diagnostic of hydrated silicates. Researchers conclude that these asteroids have not undergone the alteration processes that we see in C-class asteroids

SUSTAINABILITY ISSUES: HOW SHOULD GOVERNMENT COORDINATE FARM REGULATIONS AND POLICY?

Agricultural sustainability is an evolving process ever-seeking a balance between society's economic, environmental and social demands. Governmental policy and regulations while attempting to correct adverse externalities, have at times within themselves created adverse externalities. Failures often lie within the policies themselves, but poor coordination among government agencies is also at fault. This paper outlines a number of coordination issues and attempts to show how the empowerment of communities through ecosystem management is a partial solution to environmental degradation.Environmental regulation, Government policy, Regulation, Sustainability, Ecosystem management, Agricultural and Food Policy, Environmental Economics and Policy,

SSME single-crystal turbine blade dynamics

A study was performrd to determine the dynamic characteristics of the Space Shuttle Main Engine high pressure fuel turbopump (HPFTP) blades made of single crystal (SC) material. The first and second stage drive turbine blades of HPFTP were examined. The nonrotating natural frequencies were determined experimentally and analytically. The experimental results of the SC second stage blade were used to verify the analytical procedures. The study examined the SC first stage blade natural frequencies with respect to crystal orientation at typical operating conditions. The SC blade dynamic response was predicted to be less than the directionally solidified base. Crystal axis orientation optimization indicated that the third mode interference will exist in any SC orientation

Assessing Bottom Gear Impact in the WGOM Closure Area: A Multifaceted Approach

Mashkoor Malik presented the results of a UNH Center for Coastal and Ocean Mapping (CCOM) study of the seafloor of the WGOMCA. Objectives The objectives for the CCOM study were to: • Construct a bathymetric map of Jeffrey’s Ledge to serve as a framework for subsequent studies. • Test the potential use of multibeam sonar to monitor fishing gear impacts. • Determine if it is possible to observe closure impacts with multibeam sonar

U.S. Law of the Sea Cruise to Map and Sample the US Arctic Ocean Margin

U.S. Law of the Sea cruise to map and sample the US Arctic Ocean margin CRUISE HEALY 1202 August 25 to September 27, 2012 Barrow, AK to Dutch Harbor, A

The Price of Gold and the Exchange Rates: Once Again

This paper examines the theoretical and empirical relationships between the major exchange rates and the price of gold using forecast error data. Among other things, it is found that, since the dissolution of the Bretton Woods international monetary system, floating exchange rates among the major currencies have been a major source of price instability in the world gold market and, as the world gold market now seems to be dominated by the U.S. dollar bloc, appreciations or depreciations of that dollar would have strong effects on the price of gold in other currencies. The results of this study are rather different from those obtained in an earlier study of the same subject.

Accessibility Design and Operational Considerations in the Development of Urban Aerial Mobility Vehicles and Networks

Urban aerial mobility vehicles and networks have recently gained considerable interest in the aviation community. These small, short-range vehicles with all-electric or hybrid-electric propulsion systems, tailored to metropolitan aerial transportation needs, promise to radically change passenger mobility and cargo distribution in cities. Accessibility issues have not been a major consideration in UAM vehicle and network discussions to date. This paper seeks to help change that

U.S. Law of the Sea Cruise to Map the Foot of the Slope and 2500-m Isobath of the U.S. Arctic Ocean Margin. Cruise Report for 2008

USCGC Icebreaker Healy (WAGB-20) U.S. Law of the Sea cruise to map the foot of the slope and 2500-m isobath of the US Arctic Ocean margin CRUISES HE-0805 August 14 to September 5, 2008 Barrow, AK to Barrow, A