Low temperature annealing and cathodoluminescence studies of type 1 chondrule compositions

Preliminary results indicate that the yellow luminescing mesostases in type I chondrules can be altered by the effects of the low level thermal metamorphism. Although heat alone was insufficient to alter the CL, reheating for geologically relevant periods could have the same results as we obtained in a second series of experiments with water present. It is known that both water and solutions of sodium metasilicate greatly accelerate the devitrification of glasses. The results of the experiments that will be repeated should further clarify how the CL changes with increased thermal alteration

Determining Pesticide and Nitrate Levels in Spring Water in Northwest Arkansas

Occurrences of pesticides in our nations ground water are on the rise. As states become aware of this problem and begin monitoring programs, incidence of contamination will probably increase. Since the problem of pesticides in groundwater is relatively new, little research has centered on the fate of pesticides after they reach the groundwater environment. In Northwest Arkansas efforts to monitor groundwater for pesticides have been small. Twenty-five springs in Northwest Arkansas were sampled in the fall of 1988, and spring of 1989. Analysis for atrazine, alachlor, metolachlor, diuron, and simazine in spring water was preformed using gas liquid chromatography and high performance liquid chromatography. No detectable residues of any of the selected pesticides were found. Northwest Arkansas is a leader in poultry production. Much of the manure from poultry houses is spread on the sourounding pastures. As this litter decomposes nitrates and phosphates are released. Nitrate and phosphate concentrations were also determined on water from the spring samples. No spring exceeded the EPA\u27s limit of 45 mg/L for nitrate in drinking water. The highest concentration for phosphate in any spring was 1.05 mg/L

CMAP

This document specifies a Connection Management Access Protocol (CMAP) for call management in high-speed packet switched networks. We target CMAP to networks employing the Asynchronous Transfer Mode (ATM) communication standard. CMAP specifies the access procedues exercised by network clients to manipulate multipoint calls; it is thus a User-Network Interface (UNI) signalling protocol. We define a multipoint call as a group of multipoint connections. A multipoint connection is a communication channel between two or more clients or endpoints of the network, where all data sent by one client is received by all other clients who have elected to receive. A point-to-point connection is a special case of a multipoint connection involving only two clients. CMAP provides facilities to create, modify, and delete calls, connections, and endpoints. Once a connection is established, clients exchange data using ATM data-transfer protocols that are specified separately from CMAP

Connection Management Access Protocol (CMAP) Specification

This document specifies a Connection Management Access Protocol (CMAP) for managing multipoint connectinos in high-speed packet switched networks. We target CMAP to networks employing the Asynchronous Transfer Mode (ATM) communication standard. We define a multipoint connection as a communication channel between two or more clients of the network, where all data sent by one client is received by all other clients who have elected to receive. A point-to-point connection is a special case of a multipoint connection involving only two clients. CMAP specifies the access procedures exercised by clients to create, modify and delete multipoint connections. once a connection is established, clients exchange data using protocols that are specified separately from CMAP. To establish a multipoint connection, a client first creates a call between itself and the network. The client creating a call is designated the owner of the call. Additional endpoints are added either by invitation from the owner, invitation from another client of the network, or by explicitely requesting to be added. These three modes are sufficient for supporting point-to-point communication (for example, a telephone call), many-to-many communication (for example, a conference call or data exchange), one-to-many communication (for example, broadcast video), and many-to0one communication (for example, distributed data collection)

Fuel Distribution Estimate via Spin Period to Precession Period Ratio for the Advanced Composition Explorer

The spin period to precession period ratio of a non-axisymmetric spin-stabilized spacecraft, the Advanced Composition Explorer (ACE), was used to estimate the remaining mass and distribution of fuel within its propulsion system. This analysis was undertaken once telemetry suggested that two of the four fuel tanks had no propellant remaining, contrary to pre-launch expectations of the propulsion system performance. Numerical integration of possible fuel distributions was used to calculate moments of inertia for the spinning spacecraft. A Fast Fourier Transform (FFT) of output from a dynamics simulation was employed to relate calculated moments of inertia to spin and precession periods. The resulting modeled ratios were compared to the actual spin period to precession period ratio derived from the effect of post-maneuver nutation angle on sun sensor measurements. A Monte Carlo search was performed to tune free parameters using the observed spin period to precession period ratio over the life of the mission. This novel analysis of spin and precession periods indicates that at the time of launch, propellant was distributed unevenly between the two pairs of fuel tanks, with one pair having approximately 20% more propellant than the other pair. Furthermore, it indicates the pair of the tanks with less fuel expelled all of its propellant by 2014 and that approximately 46 kg of propellant remains in the other two tanks, an amount that closely matches the operational fuel accounting estimate. Keywords: Fuel Distribution, Moments of Inertia, Precession, Spin, Nutatio

The occurrence of blue luminescing enstatite in E3 and E4 chondrites

Two compositional types of enstatite that emit cathodoluminescence (CL) are known to exist in E3 and E4 chondrites. The first type consists of the most common enstatites that are relatively FeO-poor and emit a red CL. Their CL is apparently activated by the presence of MnO and Cr2O3 in concentrations of 0.2 and 0.6 weight percent. The second type of enstatite is nearly FeO-free, contains no MnO or Cr2O3 and emits a blue CL. The origin of these two types of enstatite and their accompanying chemical and CL differences has long been a subject of discussion. Leitch and Smith first observed to two types and felt the compositional differences were too great to have formed under the same conditions. They postulated the two types of enstatite formed on separate parent bodies and were mixed when these bodies collided. McKinley et al. observed a continuous range of compositions between blue luminescing and red luminescing enstatites and concluded the two types of enstatite formed evidence that blue luminescing pyroxenes were relics that did not completely melt during the heating event which melted other precursor grains, and are distinct from the red CL pyroxene in the chondrules in E chondrites. In order to further clarify the nature and origin of the pyroxene that emits blue CL, the sections listed in another work were examined for the occurrence of blue luminescing enstatite

Virtualization for a Network Processor Runtime System

The continuing ossification of the Internet is slowing the pace of network innovation. Network diversification presents one solution to this problem, by virtualizing the network at multiple layers. Diversified networks consist of a shared physical substrate, virtual routers (metarouters), and virtual links (metalinks). Virtualizing routers enables smooth and incremental upgrades to new network services. Our current priority for a diversified router prototype is to enable reserved slices of the network for researchers to perform repeatable, high-speed network experiments. General-purpose processors have well established techniques for virtualization, but do not scale efficiently to multi-gigabit speeds. To achieve these speeds, we employ network processors (NPs), typically consisting of multicore, multi-threaded processors with asymmetric, heterogeneous memories. The complexity and lack of hardware thread isolation in NP’s, combined with a lack of simple programming models, creates numerous challenges for effective sharing between metarouters. In this paper, we detail strategies for enabling NP virtualization at the link, memory, and processor levels, to better enable a research infrastructure for network innovation

The Open Network Laboratory (a resource for high performance networking research)

The Open Network Laboratory (ONL) is a remotely accessible network testbed designed to enable network researchers to conduct experiments using high performance routers and applications. ONL™s Remote Laboratory Interface (RLI) allows users to easily configure a network topology, initialize and modify the routers™ routing tables, packet classification tables and queuing parameters. It also enables users to add software plugins to the embedded processors available at each of the routers™ ports, enabling the introduction of new functionality. The routers provide a large number of built-in counters to track various aspects of system usage, and the RLI software makes these available through easy-to-use real-time charts. This allows researchers to expose what is happening fiunder the surfacefl enabling them to develop the insights needed to understand system behavior in complex situations and to deliver compelling demonstrations of their ideas in a realistic operating environment. This paper provides an overview of ONL, emphasizing how it can be used to carry out a wide range of networking experiments

Performance-Engineered Network Overlays for High Quality Interaction in Virtual Worlds

Overlay hosting systems such as PlanetLab, and cloud computing environments such as Amazon’s EC2, provide shared infrastructures within which new applications can be developed and deployed on a global scale. This paper ex-plores how systems of this sort can be used to enable ad-vanced network services and sophisticated applications that use those services to enhance performance and provide a high quality user experience. Specifically, we investigate how advanced overlay hosting environments can be used to provide network services that enable scalable virtual world applications and other large-scale distributed applications requiring consistent, real-time performance. We propose a novel network architecture called Forest built around per-session tree-structured communication channels that we call comtrees. Comtrees are provisioned and support both unicast and multicast packet delivery. The multicast mechanism is designed to be highly scalable and light-weight enough to support the rapid changes to multicast subscriptions needed for efficient support of state updates within virtual worlds. We evaluate performance using a combination of analysis and experimental measurement of a partial system prototype that supports fully functional distributed game sessions. Our results provide the data needed to enable accurate projections of performance for a variety of session and system configurations

Design of an Extensible Network Testbed with Heterogeneous Components

Virtualized network infrastructures are currently deployed in both research and commercial contexts. The complexity of the virtualization layer varies greatly in different deployments, ranging from cloud computing environments, to carrier Ethernet applications using stacked VLANs, to networking testbeds. In all of these cases, there are many users sharing the resources of one provider, where each user expects their resources to be isolated from all other users. Our work in this area is focused on network testbeds. In particular, we present the design of the latest version of the Open Network Laboratory (ONL) testbed. This redesign generalizes the underlying infrastructure to support resource extensibility and heterogeneity at a fundamental level. New types of resources (e.g., multicore PCs, FPGAs, network processors, etc) can be added to the testbed without modifying any testbed infrastructure software. Resource types can also be extended to support multiple distinct sets of functionality (e.g., an FPGA might act as a router, a switch, or a traffic generator). Moreover, users can dynamically add new resource extensions without any modification to the existing infrastructure