Experiments with calibrated digital sideband separating downconversion

This article reports on the first step in a focused program to re-optimize radio astronomy receiver architecture to better take advantage of the latest advancements in commercial digital technology. Specifically, an L-Band sideband-separating downconverter has been built using a combination of careful (but ultimately very simple) analog design and digital signal processing to achieve wideband downconversion of an RFI-rich frequency spectrum to baseband in a single mixing step, with a fixed-frequency Local Oscillator and stable sideband isolation exceeding 50 dB over a 12 degree C temperature range.Comment: 10 pages, 12 figures, to be published in PAS

Beta-Lactamase Repressor BlaI Modulates Staphylococcus aureus Cathelicidin Antimicrobial Peptide Resistance and Virulence.

BlaI is a repressor of BlaZ, the beta-lactamase responsible for penicillin resistance in Staphylococcus aureus. Through screening a transposon library in S. aureus Newman for susceptibility to cathelicidin antimicrobial peptide, we discovered BlaI as a novel cathelicidin resistance factor. Additionally, through integrational mutagenesis in S. aureus Newman and MRSA Sanger 252 strains, we confirmed the role of BlaI in resistance to human and murine cathelidicin and showed that it contributes to virulence in human whole blood and murine infection models. We further demonstrated that BlaI could be a target for innate immune-based antimicrobial therapies; by removing BlaI through subinhibitory concentrations of 6-aminopenicillanic acid, we were able to sensitize S. aureus to LL-37 killing

Protein L: a novel reagent for the detection of Chimeric Antigen Receptor (CAR) expression by flow cytometry

<p>Abstract</p> <p>Background</p> <p>There has been significant progress in the last two decades on the design of chimeric antigen receptors (CAR) for adoptive immunotherapy targeting tumor-associated antigens. Structurally CARs consist of a single chain antibody fragment directed against a tumor-associated antigen fused to an extracellular spacer and transmembrane domain followed by T cell cytoplasmic signaling moieties. Currently several clinical trials are underway using gene modified peripheral blood lymphocytes (PBL) with CARs directed against a variety of tumor associated antigens. Despite the improvements in the design of CARs and expansion of the number of target antigens, there is no universal flow cytometric method available to detect the expression of CARs on the surface of transduced lymphocytes.</p> <p>Methods</p> <p>Currently anti-fragment antigen binding (Fab) conjugates are most widely used to determine the expression of CARs on gene-modified lymphocytes by flow cytometry. The limitations of these reagents are that many of them are not commercially available, generally they are polyclonal antibodies and often the results are inconsistent. In an effort to develop a simple universal flow cytometric method to detect the expression of CARs, we employed protein L to determine the expression of CARs on transduced lymphocytes. Protein L is an immunoglobulin (Ig)-binding protein that binds to the variable light chains (kappa chain) of Ig without interfering with antigen binding site. Protein L binds to most classes of Ig and also binds to single-chain antibody fragments (scFv) and Fab fragments.</p> <p>Results</p> <p>We used CARs derived from both human and murine antibodies to validate this novel protein L based flow cytometric method and the results correlated well with other established methods. Activated human PBLs were transduced with retroviral vectors expressing two human antibody based CARs (anti-EGFRvIII, and anti-VEGFR2), two murine antibody derived CARs (anti-CSPG4, and anti-CD19), and two humanized mouse antibody based CARs (anti-ERBB2, and anti-PSCA). Transduced cells were stained first with biotin labeled protein L followed by phycoerythrin (PE)-conjugated streptavidin (SA) and analyzed by flow cytometry. For comparison, cells were stained in parallel with biotin conjugated goat-anti-mouse Fab or CAR specific fusion proteins. Using protein L, all CAR transduced lymphocytes exhibited specific staining pattern ranging from 40 to 80% of positive cells (compared to untransduced cells) and staining was comparable to the pattern observed with anti-Fab antibodies.</p> <p>Conclusion</p> <p>Our data demonstrate the feasibility of employing Protein L as a general reagent for the detection of CAR expression on transduced lymphocytes by flow cytometry.</p

Design of the low-speed NLF(1)-0414F and the high-speed HSNLF(1)-0213 airfoils with high-lift systems

The design and testing of Natural Laminar Flow (NLF) airfoils is examined. The NLF airfoil was designed for low speed, having a low profile drag at high chord Reynolds numbers. The success of the low speed NLF airfoil sparked interest in a high speed NLF airfoil applied to a single engine business jet with an unswept wing. Work was also conducted on the two dimensional flap design. The airfoil was decambered by removing the aft loading, however, high design Mach numbers are possible by increasing the aft loading and reducing the camber overall on the airfoil. This approach would also allow for flatter acceleration regions which are more stabilizing for cross flow disturbances. Sweep could then be used to increase the design Mach number to a higher value also. There would be some degradation of high lift by decambering the airfoil overall, and this aspect would have to be considered in a final design

Ecological Functions And Values Of Fringing Salt Marshes Susceptible To Oil Spills In Casco Bay, Maine

Casco Bay is the largest oil port in Maine and northern New England, handling over 20 million tons of crude oil and oil products annually. The susceptibility of the Bay’s estuarine habitats, especially its fringing salt marshes, to potential spill events was the impetus for this study. Although much has been learned to date about the effects of oil spills on estuarine habitats around the world, there is a real need for site-specific knowledge of the structures and functions of local habitats so that resource managers can be prepared in the event of a spill. Our study focused specifically on the value of Casco Bay’s fringing salt marshes to shellfish and finfish production, to vegetation production and diversity, and as buffers against sea level rise and coastal erosion. The work we have accomplished has been the first study of the fringing salt marshes of Casco Bay that has explored the biotic communities (fish, invertebrates and plants) of these marshes in conjunction with the physical properties of these sites. Knowledge of these local fringing salt marsh habitats will be invaluable in improving the effectiveness of oil spill cleanup operations, accurate assessment of natural resource damages caused by spills, and the restoration of impacted sites. In addition, the data acquired in this study provide an initial set of benchmarks upon which to build a program to assess long-term change in Casco Bay tidal marsh habitats