Large Area Crop Inventory Experiment (LACIE). Sampling unit size considerations in large area crop inventorying using satellite-based data

There are no author-identified significant results in this report

Estimation of within-stratum variance for sample allocation: Foreign commodity production forecasting

The problem of determining the stratum variances required for an optimum sample allocation for remotely sensed crop surveys is investigated with emphasis on an approach based on the concept of stratum variance as a function of the sampling unit size. A methodology using the existing and easily available information of historical statistics is developed for obtaining initial estimates of stratum variances. The procedure is applied to variance for wheat in the U.S. Great Plains and is evaluated based on the numerical results obtained. It is shown that the proposed technique is viable and performs satisfactorily with the use of a conservative value (smaller than the expected value) for the field size and with the use of crop statistics from the small political division level

Stratum variance estimation for sample allocation in crop surveys

The problem of determining stratum variances needed in achieving an optimum sample allocation for crop surveys by remote sensing is investigated by considering an approach based on the concept of stratum variance as a function of the sampling unit size. A methodology using the existing and easily available information of historical crop statistics is developed for obtaining initial estimates of tratum variances. The procedure is applied to estimate stratum variances for wheat in the U.S. Great Plains and is evaluated based on the numerical results thus obtained. It is shown that the proposed technique is viable and performs satisfactorily, with the use of a conservative value for the field size and the crop statistics from the small political subdivision level, when the estimated stratum variances were compared to those obtained using the LANDSAT data

An empirical, graphical, and analytical study of the relationship between vegetation indices

The development of formulae for the reduction of multispectral scanner measurements to a single value (vegetation index) for predicting and assessing vegetative characteristics is addressed. The origin, motivation, and derivation of some four dozen vegetation indices are summarized. Empirical, graphical, and analytical techniques are used to investigate the relationships among the various indices. It is concluded that many vegetative indices are very similar, some being simple algebraic transforms of others

Electronic nematicity and its relation to quantum criticality in Sr_3Ru_2O_7 studied by thermal expansion

We report high-resolution measurements of the in-plane thermal expansion anisotropy in the vicinity of the electronic nematic phase in Sr$_3$Ru$_2$O$_7$ down to very low temperatures and in varying magnetic field orientation. For fields applied along the c-direction, a clear second-order phase transition is found at the nematic phase, with critical behavior compatible with the two-dimensional Ising universality class (although this is not fully conclusive). Measurements in a slightly tilted magnetic field reveal a broken four-fold in-plane rotational symmetry, not only within the nematic phase, but extending towards slightly larger fields. We also analyze the universal scaling behavior expected for a metamagnetic quantum critical point, which is realized outside the nematic region. The contours of the magnetostriction suggest a relation between quantum criticality and the nematic phase.Comment: 8 pages, 12 Figures, invited paper at QCNP 2012 conferenc

Symmetry-breaking lattice distortion in Sr_3Ru_2O_7

The electronic nematic phase of Sr$_3$Ru$_2$O$_7$ is investigated by high-resolution in-plane thermal expansion measurements in magnetic fields close to 8 T applied at various angles $\Theta$ off the c-axis. At $\Theta<10^\circ$ we observe a very small ($10^{-7}$) lattice distortion which breaks the four-fold in-plane symmetry, resulting in nematic domains with interchanged $a$- and b-axis. At $\Theta \gtrsim 10^\circ$ the domains are almost fully aligned and thermal expansion indicates an area-preserving lattice distortion of order $2\times 10^{-6}$ which is likely related to orbital ordering. Since the system is located in the immediate vicinity to a metamagnetic quantum critical end point, the results represent the first observation of a structural relaxation driven by quantum criticality.Comment: 4 pages, 5 figures, PRL accepte

Anisotropy of the low-temperature magnetostriction of Sr3Ru2O7

We use high-resolution capacitive dilatometry to study the low-temperature linear magnetostriction of the bilayer ruthenate Sr$_3$Ru$_2$O$_7$ as a function of magnetic field applied perpendicular to the ruthenium-oxide planes ($B\parallel c$). The relative length change $\Delta L(B)/L$ is detected either parallel or perpendicular to the c-axis close to the metamagnetic region near B=8 T. In both cases, clear peaks in the coefficient $\lambda(B)=d(\Delta L/L)/dB$ at three subsequent metamagnetic transitions are observed. For $\Delta L\perp c$, the third transition at 8.1 T bifurcates at temperatures below 0.5 K. This is ascribed to the effect of an in-plane uniaxial pressure of about 15 bar, unavoidable in the dilatometer, which breaks the original fourfold in-plane symmetry.Comment: 3 pages, 3 Figures, Manuscript for Proceedings of the International Conference on Quantum Criticality and Novel Phases (QCNP09, Dresden

Imputing historical statistics, soils information, and other land-use data to crop area

In foreign crop condition monitoring, satellite acquired imagery is routinely used. To facilitate interpretation of this imagery, it is advantageous to have estimates of the crop types and their extent for small area units, i.e., grid cells on a map represent, at 60 deg latitude, an area nominally 25 by 25 nautical miles in size. The feasibility of imputing historical crop statistics, soils information, and other ancillary data to crop area for a province in Argentina is studied

A pragmatic cluster randomized controlled trial of an educational intervention for GPs in the assessment and management of depression

Background. General practitioners (GPs) can be provided with effective training in the skills to manage depression. However, it remains uncertain whether such training achieves health gain for their patients. Method. The study aimed to measure the health gain from training GPs in skills for the assessment and management of depression. The study design was a cluster randomized controlled trial. GP participants were assessed for recognition of psychological disorders, attitudes to depression, prescribing patterns and experience of psychiatry and communication skills training. They were then randomized to receive training at baseline or the end of the study. Patients selected by GPs were assessed at baseline, 3 and 12 months. The primary outcome was depression status, measured by HAM-D. Secondary outcomes were psychiatric symptoms (GHQ-12) quality of life (SF-36), satisfaction with consultations, and health service use and costs. Results. Thirty-eight GPs were recruited and 36 (95%) completed the study. They selected 318 patients, of whom 189 (59%) were successfully recruited. At 3 months there were no significant differences between intervention and control patients on HAM-D, GHQ-12 or SF-36. At 12 months there was a positive training effect in two domains of the SF-36, but no differences in HAM-D, GHQ-12 or health care costs. Patients reported trained GPs as somewhat better at listening and understanding but not in the other aspects of satisfaction. Conclusions. Although training programmes may improve GPs' skills in managing depression, this does not appear to translate into health gain for depressed patients or the health service

Holographic Recording Materials Development

Organic photorefractive materials were evaluated for application in a reversible holographic memory system. Representative indigo and thioindigo derivatives and several stilbene derivatives were studied as well as 15, 16-dialkyldihydropyrene derivatives the following goals were achieved: (1) the successful writing of phase holograms in a thioindigo/polymer gel system, (2) the successful writing and erasing of phase holograms in a variety of indigo/polymer gel and indigo/solid polymer systems, and (3) the identification of indigoid dyes and 15, 16-dialkyldihydropyrene derivatives as materials potentially suitable for utilization in an operational system. Photochemical studies of the stilbene, indigo, thioindigo, and dialkyldihydropyrene derivatives in solution and in a variety of polymer matrix materials were conducted with the goal of optimizing the photorefractive behavior of the chemical system as a whole. The spectroscopic properties required of optimal photorefractive materials were identified, and it was shown that both the indigoid dyes and the dialkyldihydropyrenes closely match the required properties