The effect of radio frequency interference on the 136- to 138-MHz return link and 400.5- to 401.5-MHz forward link of the Tracking and Data Relay Satellite System

The purpose is to update the RFI estimates in the 136- to 138-MHz VHF band and to make estimates for the first time for the 400.5- to 401.5-MHz UHF band. These preliminary predictions are based on primarily ITU frequency-registration data, with missing data bridged by engineering judgement

Interconnectivity via a consolidated type hierarchy and XML

We propose building a software system that passes any message type between legacy Command, Control, Communications, Computer, Intelligence, Surveillance and Reconnaissance (C4ISR) systems. The software system presents significant cost savings to the Department of Defense (DoD) because it allows us continued use of already purchased systems without changing the system itself. In the midst of the information age, the DoD cannot get information to the warfighter. We still maintain and use heterogeneous legacy systems, which send limited information via a set of common messages developed for a specific domain or branch of DoD. Our ability to communicate with one message format does not meet our needs today, though these stovepipe C4ISR systems still provide vital information. By combining these systems, we will have a synergistic effect on our information operations because of the shared information. Our translator will resolve data representational differences between the legacy systems using a model entitled the Common Type Hierarchy (CTH) . The CTH stores the relationships between different data representations and captures what is needed to perform translations between the different representations. We will use the platform neutral extensible Mark-up Language (XML) as an enabling technology for the CTH modelhttp://www.archive.org/details/interconnectivit00lyttCaptain, United States ArmyLieutenant, United States NavyApproved for public release; distribution is unlimited

Major RFI conditions effecting TDRSS

An evaluation of the radio frequency interference (RFI) conditions which would affect operating frequency band selections and data communications equipment design approaches for the Tracking Data Relay Satellite System (TDRSS) is presented. The subjects discussed are: (1) the scope of the investigation, (2) relative RFI in the frequency bands considered, (3) radar RFI power and duty factor, (4) radio relay communications RFI, (5) radio frequency band usage recommendations, and (6) radar RFI impact areas

Spatial linear global instability analysis of the HIFiRE-5 elliptic cone model flow

The linear instability of the three-dimensional boundary-layer over the HIFiRE-5 flight test geometry, i.e. a rounded-tip 2:1 elliptic cone, at Mach 7, has been analyzed through spatial BiGlobal analysis, in a effort to understand transition and accurately predict local heat loads on next-generation ight vehicles. The results at an intermediate axial section of the cone, Re x = 8x10 5, show three different families of spatially amplied linear global modes, the attachment-line and cross- ow modes known from earlier analyses, and a new global mode, peaking in the vicinity of the minor axis of the cone, termed \center-line mode". We discover that a sequence of symmetric and anti-symmetric centerline modes exist and, for the basic ow at hand, are maximally amplied around F* = 130kHz. The wavenumbers and spatial distribution of amplitude functions of the centerline modes are documente

Hierarchically modelling many stars to improve inference with asteroseismology

Astronomers want accurate physical properties of stars like age, mass, and radius. We can estimate these by comparing observable parameters to those from models of stellar evolution. This has been made possible on a large-scale with recent astronomical surveys and the field of asteroseismology probing inside stars. In the first chapter of this thesis, I introduce asteroseismology --- the study of stellar oscillations. I choose to focus on stars which oscillate like the Sun with masses from 0.8 to 1.2 $\mathrm{M}_{\odot}$ undergoing their main sequence and subgiant phases of evolution. To date, we have observed oscillations in hundreds of these stars. With the upcoming space-based PLATO mission, we anticipate observations of $\sim 10^4$ more solar-like oscillators. In this thesis, I aim to develop probabilistic modelling methods which can quickly and easily scale to such huge numbers of stars. Furthermore, we know our stellar models are wrong. It is important to accurately quantify this uncertainty if we are to use stellar parameters to understand stellar populations. In Chapters 2 and 3, I present a novel approach for improving the inference of fundamental stellar parameters using a hierarchical Bayesian model. I introduce a statistical treatment which 'pools' helium abundance ($Y$) and the mixing-length theory parameter ($\alpha_\mathrm{MLT}$) to incorporate information about their distributions in the population. Specifically, I model $Y$ as a distribution centred on a linear enrichment law parametrised by $\Delta Y/\Delta Z$. I test our method on a sample of dwarfs and subgiants observed by Kepler with $0.8 < M/\mathrm{M}_{\odot} < 1.2$. Exploring various levels of pooling parameters, with and without the Sun as a calibrator, I report $\Delta Y/\Delta Z = 1.05^{+0.28}_{-0.25}$ when the Sun is included in the sample. Despite marginalising over uncertainties in $Y$ and $\alpha_\mathrm{MLT}$, I am able to report statistical uncertainties of 2.5 per cent in mass, 1.2 per cent in radius, and 12 per cent in age. Moreover, my approach can be extended to larger samples. This will enable further uncertainty reduction in fundamental parameters and data-driven insight into population-level distributions. There is additional information on $Y$ to be gained from detailed asteroseismology. Acoustic glitches, which arise from rapid changes in stellar structure (e.g. from helium ionisation), leave a periodic signature in the mode frequencies ($\nu_{nl}$) of solar-like oscillators. I explore the theoretical background behind this effect in Chapter 4. Then, in Chapter 5, I present a new method for modelling glitch signatures in the radial mode frequencies using a Gaussian Process (GP). The GP provides a statistical treatment of uncertainty in the functional form of our model for $\nu_{nl}$. Using a model star and 16 Cyg A, I compare this approach to another method which models the smooth component of the function using a 4th-order polynomial. My results show that the GP method accurately determines the strength and location of glitches caused by He II ionisation and the base of the convective zone. I find that using a prior to inform the glitch parameters in my method reduces the occurrence of extreme, unrealistic solutions in the posterior. Furthermore, I demonstrate that the GP approach outperforms the polynomial by marginalising over the lesser signature of He I ionisation. However, inclusion of the He I ionisation glitch in the model remains a question. Overall, my results suggest that the GP method should be further tested on more solar-like oscillators and then integrated into the hierarchical model presented in this work

CXCR4 expression heterogeneity in neuroblastoma cells due to ligand-independent regulation

<p>Abstract</p> <p>Background</p> <p>CXCR4, the receptor for the chemokine stromal-derived factor 1 (SDF-1), has been shown to mediate many of the processes essential for cancer progression such as tumor cell proliferation, metastasis, and angiogenesis. To understand the role of CXCR4 in the biology of neuroblastoma, a disease that presents with wide spread metastases in over 50% of patients, we screened ten patient derived-neuroblastoma cell-lines for basal CXCR4 expression and sought to identify characteristics that correlate with tumor cell phenotype.</p> <p>Results</p> <p>All cell lines expressed <it>CXCR4 </it>mRNA at variable levels, that correlated well with three distinct classes of CXCR4 surface expression (low, moderate, or high) as defined by flow cytometry. Analysis of the kinetics of CXCR4 surface expression on moderate and high expressing cell lines showed a time-dependent down-regulation of the receptor that directly correlated with cell confluency, and was independent of SDF1. Cell lysates showed the presence of multiple CXCR4 isoforms with three major species of approximately 87, 67 and 55 kDa associating with high surface expression, and two distinct species of 45 and 38 kDa correlating with low to null surface expression. Western blot analysis of CXCR4 immunoprecipitates showed that the 87 and 67 kDa forms were ubiquitinated, while the others were not. Finally, treatment of cells with a proteasome inhibitor resulted in down regulation of CXCR4 surface expression.</p> <p>Conclusions</p> <p>Taken together, these data show that regulation of CXCR4 surface expression in neuroblastoma cells can occur independently of SDF-1 contribution arguing against an autocrine mechanism. Additionally these data suggest that post-translational modifications of CXCR4, in part through direct ubiquitination, can influence trafficking of CXCR4 to the surface of neuroblastoma cells in a ligand-independent manner.</p

Identification and characterization of the orf virus type I topoisomerase

AbstractVaccinia virus (VV) and Shope fibroma virus (SFV), representatives of the orthopox and leporipox genera, respectively,encode type I DNA topoisomerases. Here we report that the 957-nt F4R open reading frame of orf virus (OV), a representative of the parapox genus, is predicted to encode a 318-aa protein with extensive homology to these enzymes. The deduced amino acid sequence of F4R has 54.7 and 50.6% identity with the VV and SFV enzymes, respectively. One hundred forty amino acids are predicted to be conserved in all three proteins. The F4R protein was expressed in Escherichia coli under the control of an inducible T7 promoter, partially purified, and shown to be a bona fide type I topoisomerase. Like the VV enzyme, the OV enzyme relaxed negatively supercoiled DNA in the absence of divalent cations or ATP and formed a transient covalent intermediate with cleaved DNA that could be visualized by SDS-PAGE. Both the noncovalent and covalent protein/DNA complexes could be detected in an electrophoretic mobility shift assay. The initial PCR used to prepare expression constructs yielded a mutant allele of the OV topoisomerase with a G-A transition at nt 677 that was predicted to replace a highly conserved Tyr residue with a Cys. This allele directed the expression of an enzyme which retained noncovalent DNA binding activity but was severely impaired in DNA cleavage and relaxation. Incubation of pUC19 DNA with the wild-type OV or VV enzyme yielded an indistinguishable set of DNA cleavage fragments, although the relative abundance of the fragments differed for the two enzymes. Using a duplex oligonucleotide substrate containing the consensus site for the VV enzyme, we demonstrated that the OV enzyme also cleaved efficiently immediately downstream of the sequence CCCTT↓

A Novel Sperm-Delivered Toxin Causes Late-Stage Embryo Lethality and Transmission Ratio Distortion in C. elegans

The evolutionary fate of an allele ordinarily depends on its contribution to host fitness. Occasionally, however, genetic elements arise that are able to gain a transmission advantage while simultaneously imposing a fitness cost on their hosts. We previously discovered one such element in C. elegans that gains a transmission advantage through a combination of paternal-effect killing and zygotic self-rescue. Here we demonstrate that this element is composed of a sperm-delivered toxin, peel-1, and an embryo-expressed antidote, zeel-1. peel-1 and zeel-1 are located adjacent to one another in the genome and co-occur in an insertion/deletion polymorphism. peel-1 encodes a novel four-pass transmembrane protein that is expressed in sperm and delivered to the embryo via specialized, sperm-specific vesicles. In the absence of zeel-1, sperm-delivered PEEL-1 causes lethal defects in muscle and epidermal tissue at the 2-fold stage of embryogenesis. zeel-1 is expressed transiently in the embryo and encodes a novel six-pass transmembrane domain fused to a domain with sequence similarity to zyg-11, a substrate-recognition subunit of an E3 ubiquitin ligase. zeel-1 appears to have arisen recently, during an expansion of the zyg-11 family, and the transmembrane domain of zeel-1 is required and partially sufficient for antidote activity. Although PEEL-1 and ZEEL-1 normally function in embryos, these proteins can act at other stages as well. When expressed ectopically in adults, PEEL-1 kills a variety of cell types, and ectopic expression of ZEEL-1 rescues these effects. Our results demonstrate that the tight physical linkage between two novel transmembrane proteins has facilitated their co-evolution into an element capable of promoting its own transmission to the detriment of organisms carrying it

Psychological responses after a major fatal earthquake: The effect of preitraumatic dissociation and posttraumatic stress symptoms on anxiety and depression.

Following trauma, most people with initial symptoms of stress recover, but it is important to identify those at risk for continuing difficulties so resources are allocated appropriately. There has been limited investigation of predictors of posttraumatic stress disorder following natural disasters. This study assessed psychological difficulties experienced in 101 adult treatment seekers following exposure to a significant earthquake. Peritraumatic dissociation, posttraumatic stress symptoms, anxiety, depression, and emotional support were assessed. Path analysis was used to determine whether the experience of some psychological difficulties predicted the experience of other difficulties. As hypothesized, peritraumatic dissociation was found to predict posttraumatic stress symptoms and anxiety. Posttraumatic stress symptoms then predicted anxiety and depression. Depression and anxiety were highly correlated. Contrary to expectations, emotional support was not significantly related to other psychological variables. These findings justify the provision of psychological support following a natural disaster and suggest the benefit of assessing peritraumatic dissociation and posttraumatic stress symptoms soon after the event to identify people in need of monitoring and intervention