Aerodynamic characteristics of a hypersonic parachute

Newtonian theory, both in the form of the Modified-Newtonian and the Newton- Busemann pressure laws, is used to find the shape, cloth area and drag of the axisymmetric canopy of a hypersonic parachute, whose only load-carrying fibres are longitudinal ones. As an example, an estimate is made of the size of canopy needed to give a drag of 20,000 lb. in flight at a Mach number of 10 at 100,000 feet altitude

An algorithmic characterization of antimatroids

In an article entitled “Optimal sequencing of a single machine subject to precedence constraints” E.L. Lawler presented a now classical minmax result for job scheduling. In essence, Lawler's proof demonstrated that the properties of partially ordered sets were sufficient to solve the posed scheduling problem. These properties are, in fact, common to a more general class of combinatorial structures known as antimatroids, which have recently received considerable attention in the literature. It is demonstrated that the properties of antimatroids are not only sufficient but necessary to solve the scheduling problem posed by Lawler, thus yielding an algorithmic characterization of antimatroids. Examples of problems solvable by the general result are provided

Effect of jumping style on the performance of large and medium elite agility dogs

Dog agility is a rapidly progressing sport worldwide. Consequentially, research and methods to improve technique and performance are becoming highly sought after. Video data were collected of elite agility dogs during a training session, with downstream analysis examining differences in apparent topline angle and jumping speed of large and medium dogs as well as collie breeds and non-collie breeds. The study further examined any correlations between topline angle and jumping speed. Findings suggest that there is a difference between the jump kinematics of large and medium dogs (P=0.001) and between collie breeds and non-collie breeds (P<0.001) with collie breeds jumping faster than non-collie breeds (P=0.013). This information could be used to inform future training regimes and competitive strategies in a breed and size specific way, with the aim to improve long-term health and welfare of canine participants, whilst also ensuring that training and competitive expectations are within biological capabilities

Initial Findings from the Archeological Investigations of the Hardin A Site (41GG69), Gregg County, Texas

The Hardin A site (41GG69) is a prehistoric Caddo Indian settlement located on a high terrace overlooking the Sabine River flood-plain in Gregg County, Texas. The modem channel of the river is about 650 m to the south, and there is a small, intermittent tributary ca. 180 m to the west. The senior author discovered the Hardin A site in 1997, after he was told about it by informants who were looting a midden and cemetery area, and he formally recorded it in February 2000. In an effort to better understand the temporal and archeological context of the prehistoric Caddo occupation at the Hardin A site, limited hand excavations (Unit 1, a l x 2 m unit) were completed in the midden area by the senior author, with the assistance of Mark Walters, Texas Archeological Steward, in the spring of 2000. That work exposed deep (+90 cm) archeological deposits in a sandy loam soil with some preserved midden, as well as part of a pit feature in the northern and eastern part of the unit. The pit feature extended to approximately 160 cm below surface (bs), and contained dark brown to very dark grayish-brown fill with large amounts of ceramics (including about 50 decorated sherds), animal bone, and charred plant remains (especially hickory nutshells). Analyses are ongoing on these remains. In this paper, we discuss the results of our radiocarbon and oxidizable carbon ratio (OCR) studies in the Hardin A midden

CAN THE UNITED STATES COMPETE WITH DAIRY EXPORTING NATIONS?

International Relations/Trade,

Two Flavour QCD Phase Transition

Results on the phase transition in QCD with two flavours of light staggered fermions from an ongoing simulation are presented. We find the restoration of the chiral SU(2) x SU(2) symmetry, but not of the axial U_A(1) symmetry.Comment: LaTeX2e, amstex package. 4 pages, 2 figures. Talk presented at the 10th International Conference on Problems of Quantum Field Theory, Crime