Design and performance of an adaptive MFSK HF terminal.

The paper describes the implementation of a real-time integrated modem/codec system for long-range radio communications, e.g. HF. The system has been developed by the Hull-Lancaster Communication Research Group. The system has been implemented using a proprietary DSP-based architecture which uses the AT&T DSP32C digital signal processor and the transmission format comprises MFSK modulation combined with RS coding. The main features of the system are described and results from on-air HF trials over both static and aeromobile channels are presente

Imperfect observations in ecological studies

Every ecological data set is the result of sampling the biota at sampling locations. Such samples are rarely a census of the biota at the sampling locations and so will inherently contain biases. It is crucial to account for the bias induced by sampling if valid inference on biodiversity quantities is to be drawn from the observed data. The literature on accounting for sampling effects is large, but most are dedicated to the specific type of inference required, the type of analysis performed and the type of survey undertaken. There is no general and systematic approach to sampling. Here, we explore the unification of modelling approaches to account for sampling. We focus on individuals in ecological communities as the fundamental sampling element, and show that methods for accounting for sampling at the species level can be equated to individual sampling effects. Particular emphasis is given to the case where the probability of observing an individual, when it is present at the site sampled, is less than one. We call these situations ‘imperfect observations’. The proposed framework is easily implemented in standard software packages. We highlight some practical benefits of this formal framework: the ability of predicting the true number of individuals using an expectation that conditions on the observed data, and designing appropriate survey plans accounting forPublisher PDFPeer reviewe

Financial health indicators: an analysis of financial statement information to determine the financial health of DoD contractors

MBA Professional ReportPrior to awarding a contract, government contracting officers must be able to determine the financial health of prospective contractors. In fact, according to the Federal Acquisition Regulation (FAR) 9.104- 1(a), the very first general requirement to being considered a responsible prospective contractor is to show adequate financial resources to perform the contract or the ability to obtain financing. The purpose of this research is to identify a financial assessment framework that could assist DOD contracting officers with determining the financial health of potential DOD contractors. This research study may help DOD contracting officers determine the financial health of potential contractors prior to awarding a contract. The findings of this study provide a recommended framework that a contracting officer could follow in order to assess the financial health of a prospective contractor. The framework includes a ratio analysis using selected ratios compiled by this study, as well as a comparative analysis using industry average driven data. The framework also incorporates horizontal and vertical analyses, as well as bankruptcy and fraud analyses. The financial assessment framework created in this study is a comprehensive financial health assessment tool that can be utilized by DOD contracting officers.http://archive.org/details/financialhealthi1094551703Lieutenant Commander, United States NavyLieutenant, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited

Polymer translocation through a nanopore under an applied external field

We investigate the dynamics of polymer translocation through a nanopore under an externally applied field using the 2D fluctuating bond model with single-segment Monte Carlo moves. We concentrate on the influence of the field strength $E$, length of the chain $N$, and length of the pore $L$ on forced translocation. As our main result, we find a crossover scaling for the translocation time $\tau$ with the chain length from $\tau \sim N^{2\nu}$ for relatively short polymers to $\tau \sim N^{1 + \nu}$ for longer chains, where $\nu$ is the Flory exponent. We demonstrate that this crossover is due to the change in the dependence of the translocation velocity v on the chain length. For relatively short chains $v \sim N^{- \nu}$, which crosses over to $v \sim N^{- 1}$ for long polymers. The reason for this is that with increasing $N$ there is a high density of segments near the exit of the pore, which slows down the translocation process due to slow relaxation of the chain. For the case of a long nanopore for which $R_\parallel$, the radius of gyration $R_{g}$ along the pore, is smaller than the pore length, we find no clear scaling of the translocation time with the chain length. For large $N$, however, the asymptotic scaling $\tau \sim N^{1 + \nu}$ is recovered. In this regime, $\tau$ is almost independent of $L$. We have previously found that for a polymer, which is initially placed in the middle of the pore, there is a minimum in the escape time for $R_\parallel \approx L$. We show here that this minimum persists for a weak fields $E$ such that $EL$ is less than some critical value, but vanishes for large values of $EL$.Comment: 25 Pages, 10 figures. Submitted to J. Chem. Phys. J. Chem. Phys. 124, in press (2006

Electric Polarizability of Neutral Hadrons from Lattice QCD

By simulating a uniform electric field on a lattice and measuring the change in the rest mass, we calculate the electric polarizability of neutral mesons and baryons using the methods of quenched lattice QCD. Specifically, we measure the electric polarizability coefficient from the quadratic response to the electric field for 10 particles: the vector mesons $\rho^0$ and $K^{*0}$; the octet baryons n, $\Sigma^0$, $\Lambda_{o}^{0}$, $\Lambda_{s}^{0}$, and $\Xi^0$; and the decouplet baryons $\Delta^0$, $\Sigma^{*0}$, and $\Xi^{*0}$. Independent calculations using two fermion actions were done for consistency and comparison purposes. One calculation uses Wilson fermions with a lattice spacing of $a=0.10$fm. The other uses tadpole improved L\"usher-Weiss gauge fields and clover quark action with a lattice spacing $a=0.17$fm. Our results for neutron electric polarizability are compared to experiment.Comment: 25 pages, 20 figure

Exact solution of a linear molecular motor model driven by two-step fluctuations and subject to protein friction

We investigate by analytical means the stochastic equations of motion of a linear molecular motor model based on the concept of protein friction. Solving the coupled Langevin equations originally proposed by Mogilner et al. (A. Mogilner et al., Phys. Lett. {\bf 237}, 297 (1998)), and averaging over both the two-step internal conformational fluctuations and the thermal noise, we present explicit, analytical expressions for the average motion and the velocity-force relationship. Our results allow for a direct interpretation of details of this motor model which are not readily accessible from numerical solutions. In particular, we find that the model is able to predict physiologically reasonable values for the load-free motor velocity and the motor mobility.Comment: 12 pages revtex, 6 eps-figure

Effects of Motion Measurement Errors on Radar Target Detection

This thesis investigates the relationships present between signal-to-clutter ratios, motion measurement errors, image quality metrics, and the task of target detection, in order to discover what factor merit greater focus in order to attain the highest probability of target detection success. This investigation is accomplished by running a high number of Monte Carlo trials through a coherent target detector and analyzing the results. The aforementioned relationships are demonstrated via sample synthetic aperture radar imagery, histograms, receiver operating characteristics curves, and error bar plots

Next evolution of workforce experiential learning for 21st century global access learners

The rapid pace of technological innovations has created opportunities, but also made it difficult for higher education institutions to keep up with 21st Century workplace readiness skills for students. By the time students graduate from college and enter the workforce, many are lacking the skills and capabilities needed to be proficient in their job functions. These skill and capability gaps are even wider for global access learners, or online learners. Due to new entrants possessing skill and capability gaps, leaders in workforce development, typically housed in learning and development, talent management, or other human resources arm, have taken ownership of providing workplace learning opportunities to close the gaps and allow workers to reach their desired competency level. This qualitative study investigated the strategies and best practices employed by workforce development leaders who are implementing experiential learning opportunities for their global access learners. This phenomenological study investigated insights of 16 workforce development leaders using semi-structured interviews. The study was guided by research questions which focused on the strategies and best practices of workforce development leaders, challenges they face when leading experiential learning across the globe, ways in which they mature learning success outcomes, and recommendations for others seeking to employ learning opportunities for global access learners. The study revealed 35 key findings related to creating a learning culture and establishing a learning ecosystem which contribute toward the success of implementing global access experiential learning

A database of microRNA expression patterns in Xenopus laevis

MicroRNAs (miRNAs) are short, non-coding RNAs around 22 nucleotides long. They inhibit gene expression either by translational repression or by causing the degradation of the mRNAs they bind to. Many are highly conserved amongst diverse organisms and have restricted spatio-temporal expression patterns during embryonic development where they are thought to be involved in generating accuracy of developmental timing and in supporting cell fate decisions and tissue identity. We determined the expression patterns of 180 miRNAs in Xenopus laevis embryos using LNA oligonucleotides. In addition we carried out small RNA-seq on different stages of early Xenopus development, identified 44 miRNAs belonging to 29 new families and characterized the expression of 5 of these. Our analyses identified miRNA expression in many organs of the developing embryo. In particular a large number were expressed in neural tissue and in the somites. Surprisingly none of the miRNAs we have looked at show expression in the heart. Our results have been made freely available as a resource in both XenMARK and Xenbase

Profiling allele-specific gene expression in brains from individuals with autism spectrum disorder reveals preferential minor allele usage.

One fundamental but understudied mechanism of gene regulation in disease is allele-specific expression (ASE), the preferential expression of one allele. We leveraged RNA-sequencing data from human brain to assess ASE in autism spectrum disorder (ASD). When ASE is observed in ASD, the allele with lower population frequency (minor allele) is preferentially more highly expressed than the major allele, opposite to the canonical pattern. Importantly, genes showing ASE in ASD are enriched in those downregulated in ASD postmortem brains and in genes harboring de novo mutations in ASD. Two regions, 14q32 and 15q11, containing all known orphan C/D box small nucleolar RNAs (snoRNAs), are particularly enriched in shifts to higher minor allele expression. We demonstrate that this allele shifting enhances snoRNA-targeted splicing changes in ASD-related target genes in idiopathic ASD and 15q11-q13 duplication syndrome. Together, these results implicate allelic imbalance and dysregulation of orphan C/D box snoRNAs in ASD pathogenesis