AN ANALYSIS OF FACTORS AFFECTING THE REGIONAL COTTON BASIS

Few empirical basis studies have examined the basis in multiple regions and few have concentrated on cotton. This paper addresses this topic, examining consumption market factors that affect the cotton basis in five U.S. cotton production regions. The seemingly unrelated regression results indicate that the following factors are significant in explaining the basis: total U.S. cotton stocks and the ratio of foreign cotton stocks to foreign mill use in the Southeast and North Delta regions; regional stocks, the opportunity cost of storage and the foreign stocks to use ratio in the West Texas region; and regional stocks, total U.S. stocks, the opportunity cost of storage, and the foreign stocks to use ratio in the Desert Southwest and San Joaquin Valley regions. All significant coefficients have the hypothesized signs except the coefficient for the opportunity cost of storage and the coefficient for the ratio of foreign stocks to foreign mill use in two regions. The results indicate that the cotton basis in different regions is typically affected by different factors.cotton basis, futures markets, Marketing,

A REGIONAL COMPARISON OF U.S. COTTON BASIS PATTERNS

The basis, defined as the cash price minus the futures price, is important when making marketing decisions. The cotton basis is calculated using the July futures price for six major cotton marketing regions in the U.S. for August 1993 to November 1997. Graphs of the average basis for the four complete crop years show that the basis generally followed the expected seasonal pattern. The basis tended to be weakest at harvest and to strengthen later in the crop year. However, a visual inspection showed regional differences in the seasonal pattern. Regional differences in the yearly variability in the basis were also observed. Thus, the usefulness of the average historical basis in predicting the future basis appears to differ depending on the region.Demand and Price Analysis,

Waveguide integrated superconducting single-photon detectors with high internal quantum efficiency at telecom wavelengths

Superconducting nanowire single-photon detectors (SNSPDs) provide high efficiency for detecting individual photons while keeping dark counts and timing jitter minimal. Besides superior detection performance over a broad optical bandwidth, compatibility with an integrated optical platform is a crucial requirement for applications in emerging quantum photonic technologies. Here we present SNSPDs embedded in nanophotonic integrated circuits which achieve internal quantum efficiencies close to unity at 1550 nm wavelength. This allows for the SNSPDs to be operated at bias currents far below the critical current where unwanted dark count events reach milli-Hz levels while on-chip detection efficiencies above 70% are maintained. The measured dark count rates correspond to noise-equivalent powers in the 10-19 W/Hz-1/2 range and the timing jitter is as low as 35 ps. Our detectors are fully scalable and interface directly with waveguide-based optical platforms

Saturated configuration interaction calculations for five-valent Ta and Db

Accurate atomic structure calculations of complicated atoms with 4 or more valence electrons begin to push the memory and time limits of supercomputers. This paper presents a robust method of decreasing the size of \textit{ab initio} configuration interaction and many-body perturbation theory calculations without undermining the accuracy of the resulting atomic spectra. Our method makes it possible to saturate the CI matrix in atoms with many valence electrons. We test our method on the five-valence-electron atom tantalum and verify the convergence of the calculated energies. We then apply the method to calculate spectra and isotope shifts of tantalum's superheavy analogue dubnium. Isotope-shift calculations can be used to predict the spectra of superheavy isotopes which may be produced in astrophysical phenomena

Optical spectroscopy of complex open 4dd-shell ions Sn7+^{7+}-Sn10+^{10+}

We analyze the complex level structure of ions with many-valence-electron open [Kr] 4$d^\textrm{m}$ sub-shells ($\textrm{m}$=7-4) with ab initio calculations based on configuration-interaction many-body perturbation theory (CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra of Sn$^{7+}$-Sn$^{10+}$ ions were obtained using an electron beam ion trap. Semi-empirical spectral fits carried out with the orthogonal parameters technique and Cowan code calculations lead to 90 identifications of magnetic-dipole transitions and the determination of 79 energy ground-configuration levels, questioning some earlier EUV-line assignments. Our results, the most complete data set available to date for these ground configurations, confirm the ab initio predictive power of CI+MBPT calculations for the these complex electronic systems.Comment: 18 pages, 5 figure

A QCQP Approach to Triangulation

Triangulation of a three-dimensional point from at least two noisy 2-D images can be formulated as a quadratically constrained quadratic program. We propose an algorithm to extract candidate solutions to this problem from its semidefinite programming relaxations. We then describe a sufficient condition and a polynomial time test for certifying when such a solution is optimal. This test has no false positives. Experiments indicate that false negatives are rare, and the algorithm has excellent performance in practice. We explain this phenomenon in terms of the geometry of the triangulation problem.Comment: 14 pages, to appear in the proceedings of the 12th European Conference of Computer Vision, Firenze, Italy, 7-13 October 201