Water Tunnel Tests of the British "Squid" Projectile Type "C" with Two Alternate Flat Noses

This report covers tests to determine the performance of the "Squid" with three designs of nose, designated No. 42, No 45, and No 46. Practically the only difference in the three noses is in the diameter of the flat face, these diameters being 7.90", 8.93", and 9.95", respectivel

Water Tunnel Tests of the 7.2 Chemical Rocket

This report covers tests of a 2" diameter model of the 7.2" Chemical Rocket to determine its performance and possible means of increasing stability and reducing dispersion. The rocket was tested with the two original tails, the ring tail designated herein as No. 61 and the ring tail with extended fins designated No. 62. Three other tail designs were tested designated No. 63, No. 67, and No. 68. Of these, No. 67 was the only one that produced results superior to the No. 61 and No. 62 designs. This No. 67 Tail has extended fins similar to Tail No. 62 and projects beyond the nozzle about one diameter. Details of these tails are given in Figure 12. Tail No. 62 gave a restoring moment 50% greater than Tail No. 61, and Tail No. 67 gave a restoring moment 45% greater than Tail No. 62, both values being for 5° yaw. It is believed that Tail No. 67 represents about the best that can be done in redesigning the tail, as it produced a fairly high moment, a very large center-of-pressure eccentricity, and only one of the five tails tested has a lower drag coefficient. In this connection it should be noted that all the tails tested gave, without exception, adequate stability to the projectile to insure satisfactory flight after burning is completed. Therefore, the only benefit to be obtained from an increase in the stability above that produced by the original ring tail (No. 61) must come from whatever reduction it might effect in the dispersion occurring during the burning of the propellent. Calculation of the period of oscillation of the projectile in flight, and the equivalent wave length, makes possible a comparison of projectile performance from the standpoint of dynamic stability It can be shown that, for rockets with long burning times, the shorter the wave length for a given projectile, the less will be the dispersion. Using this measure of dispersion, Tail No. 67 would be expected to produce 1S% less dispersion than Tail No. 62, and Tail No. 62, i8% less than Tail No 61. This investigation leads to the conclusion that the No. 61, No. 62, and No. 67 Tails will give a high degree of static stability and it is improbable that much more can be accomplished by a redesign of the tail. It is also a fact that the dynamic stability of the projectile cannot be materially improved if its present physical dimensions are to be retained. The conclusion must, therefore, be reached that the most effective means of lowering the dispersion of this rocket is by reducing the malalignment of the jet with the axis of the projectile and eliminating as far as possible asymmetry in the tail assembly

Rare coral under the genomic microscope: timing and relationships among Hawaiian Montipora

Background Evolutionary patterns of scleractinian (stony) corals are difficult to infer given the existence of few diagnostic characters and pervasive phenotypic plasticity. A previous study of Hawaiian Montipora (Scleractinia: Acroporidae) based on five partial mitochondrial and two nuclear genes revealed the existence of a species complex, grouping one of the rarest known species (M. dilatata, which is listed as Endangered by the International Union for Conservation of Nature - IUCN) with widespread corals of very different colony growth forms (M. flabellata and M. cf. turgescens). These previous results could result from a lack of resolution due to a limited number of markers, compositional heterogeneity or reflect biological processes such as incomplete lineage sorting (ILS) or introgression. Results All 13 mitochondrial protein-coding genes from 55 scleractinians (14 lineages from this study) were used to evaluate if a recent origin of the M. dilatata species complex or rate heterogeneity could be compromising phylogenetic inference. Rate heterogeneity detected in the mitochondrial data set seems to have no significant impacts on the phylogenies but clearly affects age estimates. Dating analyses show different estimations for the speciation of M. dilatata species complex depending on whether taking compositional heterogeneity into account (0.8 [0.05–2.6] Myr) or assuming rate homogeneity (0.4 [0.14–0.75] Myr). Genomic data also provided evidence of introgression among all analysed samples of the complex. RADseq data indicated that M. capitata colour morphs may have a genetic basis. Conclusions Despite the volume of data (over 60,000 SNPs), phylogenetic relationships within the M. dilatata species complex remain unresolved most likely due to a recent origin and ongoing introgression. Species delimitation with genomic data is not concordant with the current taxonomy, which does not reflect the true diversity of this group. Nominal species within the complex are either undergoing a speciation process or represent ecomorphs exhibiting phenotypic polymorphisms.info:eu-repo/semantics/publishedVersio

Time-optimal synthesis of unitary transformations in coupled fast and slow qubit system

In this paper, we study time-optimal control problems related to system of two coupled qubits where the time scales involved in performing unitary transformations on each qubit are significantly different. In particular, we address the case where unitary transformations produced by evolutions of the coupling take much longer time as compared to the time required to produce unitary transformations on the first qubit but much shorter time as compared to the time to produce unitary transformations on the second qubit. We present a canonical decomposition of SU(4) in terms of the subgroup SU(2)xSU(2)xU(1), which is natural in understanding the time-optimal control problem of such a coupled qubit system with significantly different time scales. A typical setting involves dynamics of a coupled electron-nuclear spin system in pulsed electron paramagnetic resonance experiments at high fields. Using the proposed canonical decomposition, we give time-optimal control algorithms to synthesize various unitary transformations of interest in coherent spectroscopy and quantum information processing.Comment: 8 pages, 3 figure

Spectroscopy of Quasar Candidates from SDSS Commissioning Data

The Sloan Digital Sky Survey has obtained images in five broad-band colors for several hundred square degrees. We present color-color diagrams for stellar objects, and demonstrate that quasars are easily distinguished from stars by their distinctive colors. Follow-up spectroscopy in less than ten nights of telescope time has yielded 22 new quasars, 9 of them at $z> 3.65$, and one with $z = 4.75$, the second highest-redshift quasar yet known. Roughly 80% of the high-redshift quasar candidates selected by color indeed turn out to be high-redshift quasars.Comment: 4 pages, 3 figures, to appear in the proceedings of "After the Dark Ages: When Galaxies were Young (the Universe at 2<z<5)", 9th Annual October Astrophysics Conference in Marylan

Intergenomic and epistatic interactions control free radical mediated pancreatic β-cell damage.

Alloxan (AL)-generated Reactive Oxygen Species (ROS) selectively destroy insulin-producing pancreatic β-cells. A previous genome-wide scan (GWS) using a cohort of 296 F2 hybrids between NOD (AL-sensitive) and ALR (AL-resistant) mice identified linkages contributing to β-cell susceptibility or resistance to AL-induced diabetes on Chromosomes (Chr) 2, 3, 8, and a single nucleotide polymorphism i

Hydrologic Modeling of the Fox River Watershed

published or submitted for publicationis peer reviewedOpe

The Angular Clustering of Galaxy Pairs

We identify close pairs of galaxies from 278 deg^2 of Sloan Digital Sky Survey commissioning imaging data. The pairs are drawn from a sample of 330,041 galaxies with 18 < r^* < 20. We determine the angular correlation function of galaxy pairs, and find it to be stronger than the correlation function of single galaxies by a factor of 2.9 +/- 0.4. The two correlation functions have the same logarithmic slope of 0.77. We invert Limber's equation to estimate the three-dimensional correlation functions; we find clustering lengths of r_0= 4.2 +/- 0.4 h^{-1} Mpc for galaxies and 7.8 +/- 0.7 h^{-1} Mpc for galaxy pairs. These results agree well with the global richness dependence of the correlation functions of galaxy systems.Comment: 12 pages. ApJ, in pres

High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data IV: Luminosity Function from the Fall Equatorial Stripe Sampl

This is the fourth paper in a series aimed at finding high-redshift quasars from five-color imaging data taken along the Celestial Equator by the SDSS. during its commissioning phase. In this paper, we use the color-selected sample of 39 luminous high-redshift quasars presented in Paper III to derive the evolution of the quasar luminosity function over the range of 3.6<z<5.0, and -27.5<M_1450<-25.5 (Omega=1, H_0=50 km s^-1 Mpc^-1). We use the selection function derived in Paper III to correct for sample incompleteness. The luminosity function is estimated using three different methods: (1) the 1/V_a estimator; (2) a maximum likelihood solution, assuming that the density of quasars depends exponentially on redshift and as a power law in luminosity and (3) Lynden-Bell's non-parametric C^- estimator. All three methods give consistent results. The luminous quasar density decreases by a factor of ~ 6 from z=3.5 to z=5.0, consistent with the decline seen from several previous optical surveys at z<4.5. The luminosity function follows psi(L) ~ L^{-2.5} for z~4 at the bright end, significantly flatter than the bright end luminosity function psi(L) \propto L^{-3.5} found in previous studies for z<3, suggesting that the shape of the quasar luminosity function evolves with redshift as well, and that the quasar evolution from z=2 to 5 cannot be described as pure luminosity evolution. Possible selection biases and the effect of dust extinction on the redshift evolution of the quasar density are also discussed.Comment: AJ accepted, with minor change