An Examination of Six “Nutting Stones” from East Texas for Plant Phytoliths

In this article we report on an examination of six nutting stones from East Texas sites as well as an exploratory examination of their possible functions. “Nutting stones” have long been presumed to have been used prehistorically for crushing nuts such as hickory, etc. as foodstuffs. In fact Davis described them as being: A small flat stone, usually made of limestone, sandstone or other sedimentary types of rock which could be carried by hand. The flat surface may have one or more ground or pecked cups of various sizes, shapes and depth. It is postulated that they were used for various purposes such as cracking nuts, mixing pigments, milling herbs and seeds, or as an anvil for flint knapping. While Davis is an avocationalist and numerous professional archaeologists have dealt with nutting stones, we know of neither a more complete definition nor any other effort to empirically test for their function

CARBON DYNAMICS IN A PHRAGMITES AUSTRALIS INVADED RIPARIAN WETLAND

Invasive plant species are widely recognized as a major threat to biodiversity and ecosystem stability. Wetland ecosystems tend to be much more susceptible to invasions because of their location on the landscape where water, nutrients, and the impacts of disturbances accumulate. Invasive plants have the ability to alter ecosystem processes and community/population dynamics. The ability of invasive plants to alter these processes can have profound economic consequences. In the United States, control of invasive wetland species alone costs approximately 155 million dollars annually. The state of Nebraska spends 2 million dollars annually controlling invasive plant species in the Platte River and Republican River basins with Phragmites australis being the main focus of these efforts. P. australis can alter ecosystem processes, such as biogeochemical cycling through its aggressive growth strategy. Our objective was to quantify the effects the P. australis invasion has on biogechemical cycling, specifically the carbon cycle, within an invaded freshwater, riparian wetland in the Great Plains (Republican River Basin, NE). This study used a dynamic closed chamber approach to measure carbon dioxide (CO2) fluxes and production, and a static chamber to quantify methane (CH4) emissions. Measurements were taken 5 times throughout the growing season of 2009 at peak gross primary production in open water, native vegetation (Scirpus sp.), and P. australis habitats. Average rates of net ecosystem exchange of carbon (NEE) were 53 ± 93, 258 ± 186, and 920 ± 752 mg C m-2 hr-1 for open water, Scirpus sp., and P. australis habitats respectively. The study found P. australis significantly increased NEE (F8,44 = 11.96; p \u3c0.001), while methanogenesis was not significantly altered. The invasion of P. australis increased aboveground biomass to 5394 ± 1815 g m-2 from 564.2 ± 139.2 g m-2 in native habitats. The ability of P. australis to increase NEE and biomass productions compared to native species at our wetland site results in an increase in carbon sequestration and a decrease in global warming potentials

Modeling Living Shorelines in a Wave Tank: Quantifying Wave Attenuation to Find the Most Effective Shoreline Restoration

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Surface areas of equifacetal polytopes inscribed in the unit sphere S2\mathbb{S}^2

This article is concerned with the problem of placing seven or eight points on the unit sphere $\mathbb{S}^2$ in $\mathbb{R}^3$ so that the surface area of the convex hull of the points is maximized. In each case, the solution is given for convex hulls with congruent isosceles or congruent equilateral triangular facets.Comment: 13 pages, 1 table, 15 figure

Time Series Measurements of Chlorophyll Fluorescence in the Oceanic Bottom Boundary Layer With a Multisensor Fiber-Optic Fluorometer

An in situ multisensor fiber-optic fluorometer (MFF) has been developed to acquire long-term chlorophyll fluorescence measurements in the oceanic bottom boundary layer to characterize the finescale pigment structure at vertical spatial scales comparable to physical measurements. The eight fluorescence sensors of the MFF are composed of dual optical fibers of varying lengths (1.5-8 m), with the fiber ends oriented at 30 degrees to each other and enclosed by a small light baffle. Strobe excitation blue light is passed through one of each pair of optical fibers and stimulated chlorophyll fluorescence is carried back to a photomultiplier. Two sets of four fluorescence sensors assigned to high- and low-sensitivity photomultiplier detectors enable chlorophyll a measurements in two ranges, 0-50 mg m(-3) and 0-200 mg m(-3), respectively. Aspects of the design of the fiber-optic sensor are described that were intended to optimize detection of fluorescence signals and minimize interference by ambient light. The fiber-optic sensor outputs were stable with minimal instrument drift during long-term field operations, and measurements were not affected by turbidity and ambient light. A vertical array of fiber-optic fluorescence sensors supported on a tripod has been deployed at coastal sites for up to seven weeks and chlorophyll fluorescence was obtained with sufficiently high vertical spatial and temporal resolution

The role of the cloud radiative effect in the sensitivity of the Intertropical Convergence Zone to convective mixing

Studies have shown that the location and structure of the simulated Intertropical Convergence Zone (ITCZ) is sensitive to the treatment of sub-gridscale convection and cloud-radiation interactions. This sensitivity remains in idealised aquaplanet experiments with fixed surface temperatures. However, studies have not considered the role of cloud-radiative effects (CRE, atmospheric heating due to cloud-radiation interactions) in the sensitivity of the ITCZ to the treatment of convection. We use an atmospheric energy input (AEI) framework to explore how the CRE modulates the sensitivity of the ITCZ to convective mixing in aquaplanet simulations. Simulations show a sensitivity of the ITCZ to convective mixing, with stronger convective mixing favoring a single ITCZ. For simulations with a single ITCZ, the CRE maintains the positive, equatorial AEI. To explore the role of the CRE further, we prescribe the CRE as either zero or a meridionally and diurnally varying climatology. Removing the CRE is associated with a reduced equatorial AEI and an increase in the range of convective mixing rates that produce a double ITCZ. Prescribing the CRE reduces the sensitivity of the ITCZ to convective mixing by 50%. In prescribed CRE simulations, other AEIcomponents, in particular the surface latent heat flux, modulate the sensitivity of the AEI to convective mixing. Analysis of the meridional moist static energy transport shows that a shallower Hadley circulation can produce an equatorward energy transport at low latitudes even with equatorial ascent

Nautilus ROV Robot Manipulator

Global warming and climate change are prevalent issues in today’s society. As a result, research in the ocean, our world’s biggest ecosystem, is imperative in efforts to protect the environment. Santa Clara University’s Robotic Systems Lab contributes to this field through work and developments on remotely operated vehicles (ROVs). An existing ROV system called Nautilus consists of a robot arm, end effector, and storage system in order to collect various types of sediments at a depth of 300 feet. However, the previous system does not meet that requirement. In direct collaboration with researchers within the Monterey Bay Aquarium Research Institute, we were able to create and accomplish a set of deliverables to improve our ROV. Our team’s main goal was to make the system functional and more efficient by redesigning the manipulator arm and soft gripper in order to retrieve samples, as well as creating a sample storage container that is in view of the camera or workspace to document and record the location of those samples. Our project gives researchers a cheaper alternative compared to existing sample collection methods, which are relatively more expensive, so that they can continue to explore and document stretches of the ocean far more easily. The project was done with the guidance of faculty in the Robotic Systems Lab as well as researchers from the Monterey Bay Aquarium Research Institute (MBARI)

Potential markets for advanced satellite communications

This report identifies trends in the volume and type of traffic offered to the U.S. domestic communications infrastructure and extrapolates these trends through the year 2011. To describe how telecommunications service providers are adapting to the identified trends, this report assesses the status, plans, and capacity of the domestic communications infrastructure. Cable, satellite, and radio components of the infrastructure are examined separately. The report also assesses the following major applications making use of the infrastructure: (1) Broadband services, including Broadband Integrated Services Digital Network (BISDN), Switched Multimegabit Data Service (SMDS), and frame relay; (2) mobile services, including voice, location, and paging; (3) Very Small Aperture Terminals (VSAT), including mesh VSAT; and (4) Direct Broadcast Satellite (DBS) for audio and video. The report associates satellite implementation of specific applications with market segments appropriate to their features and capabilities. The volume and dollar value of these market segments are estimated. For the satellite applications able to address the needs of significant market segments, the report also examines the potential of each satellite-based application to capture business from alternative technologies