3,975 research outputs found

    Naval Expeditionary Readiness Model

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    Naval expeditionary forces lack the ability to adequately estimate the level of spending required to achieve a minimum level of readiness. Currently the Navy Expeditionary Combat Enterprise (NECE) Capability Costing Model (NCCM) forecasts requirements using Excel Solver and data from the Optimized Fleet Response Plan (OFRP) and Certified Obligation Reports. To explore methods of improving requirement forecasts, this research limits its focus to one program, Explosive Ordinance Disposal (EOD), one component, active duty, and one training and testing data split. It then attempts multiple forecasting methods over multiple levels of cost aggregation. These forecasting methods include Exponential Smoothing, Autoregressive Integrated Moving Averages (ARIMA), and dynamic regression models. The analysis then evaluates models made with those methods using the accuracy measures of absolute error (MAE), mean absolute percentage error (MAPE), and mean absolute scaled error (MASE). It also attempts hierarchical models to forecast costs and evaluates those models in the same way. Finally, it calculates forecasts for two years in the future and compares those forecasts to actual costs. This final calculation mimics the process required in the Program Objective Memorandum (POM) process. This technical report finds that the various models forecast at different levels of accuracy across different levels of cost aggregation. The most accurate model to forecast total EOD costs two years in the future is an ARIMA model. It possesses a 10 percent delta in its forecast. The best aggregated model is an exponential smoothing model for the Budget Submitting Office (BSO) 60 and the warfare pillars of personnel (P) and training (T). Its delta is three percent. However, some levels of aggregation are much worse, with the best model possessing a delta of 36 percent for BSO 70 for supply (S) and equipment (E) costs. This technical report ends with several recommendations for future research.Approved for public release; distribution is unlimited.Naval Postgraduate School, Naval Research Program (PE 0605853N/2098)Naval Postgraduate School, Naval Research Program, Monterey, CA Integration of Capabilities and Resources (N81). Service Integration and Policy, Washington, D

    Metal-insulator transition in three dimensional Anderson model: universal scaling of higher Lyapunov exponents

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    Numerical studies of the Anderson transition are based on the finite-size scaling analysis of the smallest positive Lyapunov exponent. We prove numerically that the same scaling holds also for higher Lyapunov exponents. This scaling supports the hypothesis of the one-parameter scaling of the conductance distribution. From the collected numerical data for quasi one dimensional systems up to the system size 24 x 24 x infinity we found the critical disorder 16.50 < Wc < 16.53 and the critical exponent 1.50 < \nu < 1.54. Finite-size effects and the role of irrelevant scaling parameters are discussed.Comment: 4 pages, 2 figure

    Multifractal properties of critical eigenstates in two-dimensional systems with symplectic symmetry

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    The multifractal properties of electronic eigenstates at the metal-insulator transition of a two-dimensional disordered tight-binding model with spin-orbit interaction are investigated numerically. The correlation dimensions of the spectral measure D~2\widetilde{D}_{2} and of the fractal eigenstate D2D_{2} are calculated and shown to be related by D2=2D~2D_{2}=2\widetilde{D}_{2}. The exponent η=0.35±0.05\eta=0.35\pm 0.05 describing the energy correlations of the critical eigenstates is found to satisfy the relation η=2D2\eta=2-D_{2}.Comment: 6 pages RevTeX; 3 uuencoded, gzipped ps-figures to appear in J. Phys. Condensed Matte

    Anderson transitions in three-dimensional disordered systems with randomly varying magnetic flux

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    The Anderson transition in three dimensions in a randomly varying magnetic flux is investigated in detail by means of the transfer matrix method with high accuracy. Both, systems with and without an additional random scalar potential are considered. We find a critical exponent of ν=1.45±0.09\nu=1.45\pm0.09 with random scalar potential. Without it, ν\nu is smaller but increases with the system size and extrapolates within the error bars to a value close to the above. The present results support the conventional classification of universality classes due to symmetry.Comment: 4 pages, 2 figures, to appear in Phys. Rev.

    Nanopore direct RNA sequencing maps the complexity of Arabidopsis mRNA processing and m6A modification

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    Understanding genome organization and gene regulation requires insight into RNA transcription, processing and modification. We adapted nanopore direct RNA sequencing to examine RNA from a wild-type accession of the model plant Arabidopsis thaliana and a mutant defective in mRNA methylation (m6A). Here we show that m6A can be mapped in full-length mRNAs transcriptome-wide and reveal the combinatorial diversity of cap-associated transcription start sites, splicing events, poly(A) site choice and poly(A) tail length. Loss of m6A from 3’ untranslated regions is associated with decreased relative transcript abundance and defective RNA 30 end formation. A functional consequence of disrupted m6A is a lengthening of the circadian period. We conclude that nanopore direct RNA sequencing can reveal the complexity of mRNA processing and modification in full-length single molecule reads. These findings can refine Arabidopsis genome annotation. Further, applying this approach to less well-studied species could transform our understanding of what their genomes encode

    The Anderson transition: time reversal symmetry and universality

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    We report a finite size scaling study of the Anderson transition. Different scaling functions and different values for the critical exponent have been found, consistent with the existence of the orthogonal and unitary universality classes which occur in the field theory description of the transition. The critical conductance distribution at the Anderson transition has also been investigated and different distributions for the orthogonal and unitary classes obtained.Comment: To appear in Physical Review Letters. Latex 4 pages with 4 figure

    Establishing the extent of malaria transmission and challenges facing pre-elimination in the Republic of Djibouti.

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    BACKGROUND: Countries aiming for malaria elimination require a detailed understanding of the current intensity of malaria transmission within their national borders. National household sample surveys are now being used to define infection prevalence but these are less efficient in areas of exceptionally low endemicity. Here we present the results of a national malaria indicator survey in the Republic of Djibouti, the first in sub-Saharan Africa to combine parasitological and serological markers of malaria, to evaluate the extent of transmission in the country and explore the potential for elimination. METHODS: A national cross-sectional household survey was undertaken from December 2008 to January 2009. A finger prick blood sample was taken from randomly selected participants of all ages to examine for parasitaemia using rapid diagnostic tests (RDTs) and confirmed using Polymerase Chain Reaction (PCR). Blood spots were also collected on filter paper and subsequently used to evaluate the presence of serological markers (combined AMA-1 and MSP-119) of Plasmodium falciparum exposure. Multivariate regression analysis was used to determine the risk factors for P. falciparum infection and/or exposure. The Getis-Ord G-statistic was used to assess spatial heterogeneity of combined infections and serological markers. RESULTS: A total of 7151 individuals were tested using RDTs of which only 42 (0.5%) were positive for P. falciparum infections and confirmed by PCR. Filter paper blood spots were collected for 5605 individuals. Of these 4769 showed concordant optical density results and were retained in subsequent analysis. Overall P. falciparum sero-prevalence was 9.9% (517/4769) for all ages; 6.9% (46/649) in children under the age of five years; and 14.2% (76/510) in the oldest age group (≥50 years). The combined infection and/or antibody prevalence was 10.5% (550/4769) and varied from 8.1% to 14.1% but overall regional differences were not statistically significant (χ2=33.98, p=0.3144). Increasing age (p<0.001) and decreasing household wealth status (p<0.001) were significantly associated with increasing combined P. falciparum infection and/or antibody prevalence. Significant P. falciparum hot spots were observed in Dikhil region. CONCLUSION: Malaria transmission in the Republic of Djibouti is very low across all regions with evidence of micro-epidemiological heterogeneity and limited recent transmission. It would seem that the Republic of Djibouti has a biologically feasible set of pre-conditions for elimination, however, the operational feasibility and the potential risks to elimination posed by P. vivax and human population movement across the sub-region remain to be properly established

    Geometrical structure effect on localization length of carbon nanotubes

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    The localization length and density of states of carbon nanotubes are evaluated within the tight-binding approximation. By comparison with the corresponding results for the square lattice tubes, it is found that the hexagonal structure affects strongly the behaviors of the density of states and localization lengths of carbon nanotubes.Comment: 7 pages, 4 figures, revised version to appear in Chin. Phys. Lett. The title is changed. Some arguments are adde

    Localization Transition in Multilayered Disordered Systems

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    The Anderson delocalization-localization transition is studied in multilayered systems with randomly placed interlayer bonds of density pp and strength tt. In the absence of diagonal disorder (W=0), following an appropriate perturbation expansion, we estimate the mean free paths in the main directions and verify by scaling of the conductance that the states remain extended for any finite pp, despite the interlayer disorder. In the presence of additional diagonal disorder (W>0W > 0) we obtain an Anderson transition with critical disorder WcW_c and localization length exponent ν\nu independently of the direction. The critical conductance distribution Pc(g)P_{c}(g) varies, however, for the parallel and the perpendicular directions. The results are discussed in connection to disordered anisotropic materials.Comment: 10 pages, Revtex file, 8 postscript files, minor change

    Disordered Electrons in a Strong Magnetic Field: Transfer Matrix Approaches to the Statistics of the Local Density of States

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    We present two novel approaches to establish the local density of states as an order parameter field for the Anderson transition problem. We first demonstrate for 2D quantum Hall systems the validity of conformal scaling relations which are characteristic of order parameter fields. Second we show the equivalence between the critical statistics of eigenvectors of the Hamiltonian and of the transfer matrix, respectively. Based on this equivalence we obtain the order parameter exponent α03.4\alpha_0\approx 3.4 for 3D quantum Hall systems.Comment: 4 pages, 3 Postscript figures, corrected scale in Fig.
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