Expression of Tn1/3 Transposase

It has previously been shown that the only sequences near the termini of Tn1/3 essential for the first step of the transposition process of these elements are the two 38bp. perfect inverted repeats at the extreme ends of the elements. This finding has been confirmed and it has also been shown that both of these sequences are equally good substrates for transposition. Also, it was shown that Tn1/3 transposition normally acts to replicate the DNA sequences that correspond to the entire transposon sequences. Further indirect evidence for the binding of Tn1 transposase to the inverted repeat sequences of Tn1/3 was obtained, supporting the hypothesis that it is to and upon these sequences that transposase binds and acts. The location of the HincII site present in Tn1 but absent in Tn3 has , also been determined by DNA sequencing and found to be at a position in Tn1 equivalent to co-ordinates 3037-3042 in Tn3, with cleavage occurring between base pairs 3039 and 3040. Thus, this site lies just within the tnpA gene coding region, near its N-terminal end. The sequence of 114bp. of Tn1 lying to the left of this site (i.e. extending towards the C-terminus of the tnpA gene) was determined and was found to have 97/114 bp. (=85 1%) homology at the DNA level and 37/38 residue (=97.4%) homology at the amino acid level with Tn3. This confirmed the prediction of a high degree of homology between the two elements, which had been made on the basis of their very similar restriction profiles. Using this information, a plamid (pSN015) was constructed that produced a fusion protein consisting of the whole Tn1 transposase protein with its three N-terminal amino acid residues removed and replaced by the first eleven N-terminal amino acid residues of B-galactosidase. As judged by the analysis of plasmid encoded proteins expressed in E. coli K-12 minicells, pSN015 did produce more protein than the derepressed Tn1 derivative Tn103 carried on a plasmid (pMB9) with a copy number c. 1/4 of that of pSN015. Yet the transposition of Tn3651 mediated in trans by each of these plasmids occurred at very similar frequencies at both 3

Extreme UV QSOs

We present a sample of spectroscopically confirmed QSOs with FUV-NUV color (as measured by GALEX photometry) bluer than canonical QSO templates and than the majority of known QSOs. We analyze their FUV to NIR colors, luminosities and optical spectra. The sample includes a group of 150 objects at low redshift (z $<$ 0.5), and a group of 21 objects with redshift 1.7$<$z$<$2.6. For the low redshift objects, the "blue" FUV-NUV color may be caused by enhanced Ly$\alpha$ emission, since Ly$\alpha$ transits the GALEX FUV band from z=0.1 to z=0.47. Synthetic QSO templates constructed with Ly$\alpha$ up to 3 times stronger than in standard templates match the observed UV colors of our low redshift sample. The H$\alpha$ emission increases, and the optical spectra become bluer, with increasing absolute UV luminosity. The UV-blue QSOs at redshift about 2, where the GALEX bands sample restframe about 450-590A (FUV) and about 590-940A(NUV), are fainter than the average of UV-normal QSOs at similar redshift in NUV, while they have comparable luminosities in other bands. Therefore we speculate that their observed FUV-NUV color may be explained by a combination of steep flux rise towards short wavelengths and dust absorption below the Lyman limit, such as from small grains or crystalline carbon. The ratio of Ly$\alpha$ to CIV could be measured in 10 objects; it is higher (30% on average) than for UV-normal QSOs, and close to the value expected for shock or collisional ionization. FULL VERSION AVAILABLE FROM AUTHOR'S WEB SITE: http://dolomiti.pha.jhu.edu/papers/2009_AJ_Extreme_UV_QSOs.pdfComment: Astronomical Journal, in pres

Volumes and bulk densities of forty asteroids from ADAM shape modeling

Disk-integrated photometric data of asteroids do not contain accurate information on shape details or size scale. Additional data such as disk-resolved images or stellar occultation measurements further constrain asteroid shapes and allow size estimates. We aim to use all available disk-resolved images of about forty asteroids obtained by the Near-InfraRed Camera (Nirc2) mounted on the W.M. Keck II telescope together with the disk-integrated photometry and stellar occultation measurements to determine their volumes. We can then use the volume, in combination with the known mass, to derive the bulk density. We download and process all asteroid disk-resolved images obtained by the Nirc2 that are available in the Keck Observatory Archive (KOA). We combine optical disk-integrated data and stellar occultation profiles with the disk-resolved images and use the All-Data Asteroid Modeling (ADAM) algorithm for the shape and size modeling. Our approach provides constraints on the expected uncertainty in the volume and size as well. We present shape models and volume for 41 asteroids. For 35 asteroids, the knowledge of their mass estimates from the literature allowed us to derive their bulk densities. We clearly see a trend of lower bulk densities for primitive objects (C-complex) than for S-complex asteroids. The range of densities in the X-complex is large, suggesting various compositions. Moreover, we identified a few objects with rather peculiar bulk densities, which is likely a hint of their poor mass estimates. Asteroid masses determined from the Gaia astrometric observations should further refine most of the density estimates.Comment: Accepted for publication in A&

Submaximal Oxygen Uptake Kinetics, Functional Mobility, and Physical Activity in Older Adults with Heart Failure and Reduced Ejection Fraction

Background: Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. Methods: Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls. Assessments included a maximal treadmill test for peak oxygen uptake (VO2peak), oxygen uptake kinetics at onset of and on recovery from a submaximal treadmill test, functional mobility testing [Get Up and Go (GUG), Comfortable Gait Speed (CGS), Unipedal Stance (US)], and self-reported physical activity (PA). Results: Compared to controls, HF had worse performance on GUG, CGS, and US, greater delays in submaximal oxygen uptake kinetics, and lower PA. In controls, VO2peak was more strongly associated with functional mobility and PA than submaximal oxygen uptake kinetics. In HF patients, submaximal oxygen uptake kinetics were similarly associated with GUG and CGS as VO2peak, but weakly associated with PA. Conclusions: Based on their mobility performance, older HF patients with reduced ejection fraction are at risk for adverse functional outcomes. In this population, submaximal oxygen uptake measures may be equivalent to VO2 peak in predicting functional mobility, and in addition to being more feasible, may provide better insight into how aerobic function relates to mobility in older adults with HF

Covalent antibody display—an in vitro antibody-DNA library selection system

The endonuclease P2A initiates the DNA replication of the bacteriophage P2 by making a covalent bond with its own phosphate backbone. This enzyme has now been exploited as a new in vitro display tool for antibody fragments. We have constructed genetic fusions of P2A with single-chain antibodies (scFvs). Linear DNA of these fusion proteins were processed in an in vitro coupled transcription–translation mixture of Escherichia coli S30 lysate. Complexes of scFv–P2A fusion proteins covalently bound to their own DNA were isolated after panning on immobilized antigen, and the enriched DNAs were recovered by PCR and prepared for the subsequent cycles of panning. We have demonstrated the enrichment of scFvs from spiked libraries and the specific selection of different anti-tetanus toxoid scFvs from a V-gene library with 50 million different members prepared from human lymphocytes. This covalent antibody display technology offers a complete in vitro selection system based exclusively on DNA–protein complexes

Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes

Asteroid sizes can be directly measured by observing occultations of stars by asteroids. When there are enough observations across the path of the shadow, the asteroid's projected silhouette can be reconstructed. Asteroid shape models derived from photometry by the lightcurve inversion method enable us to predict the orientation of an asteroid for the time of occultation. By scaling the shape model to fit the occultation chords, we can determine the asteroid size with a relative accuracy of typically ~ 10%. We combine shape and spin state models of 44 asteroids (14 of them are new or updated models) with the available occultation data to derive asteroid effective diameters. In many cases, occultations allow us to reject one of two possible pole solutions that were derived from photometry. We show that by combining results obtained from lightcurve inversion with occultation timings, we can obtain unique physical models of asteroids.Comment: 33 pages, 45 figures, 4 tables, accepted for publication in Icaru

Fortifying or fragmenting the state? The political economy of the drug trade in Shan State, Myanmar, 1988-2012

Over the past twenty-five years, the government of Myanmar (Burma) has consolidated control over large parts of Shan State, neutralizing much of the threat posed by armed groups and strengthening its hold over revenue extraction. During this period Myanmar has retained its position as the world's second largest producer of illicit opium, much of which is converted into heroin within the country's borders. This article explores the relationship between state-building processes and the illicit opium/heroin economy in Shan State since 1988. The author has four aims. First, to reassess the theoretical assumptions that equate illicit economies with state fragility and demonstrate instead why illicit drug economies can become embedded in processes of conflict reduction and state consolidation. Second, to explain why establishing control over Shan State has become so important to the Myanmar government's state-building ambitions. Third, to analyze how the state's engagement with the drug trade has become a vital part of its attempts to consolidate control, in terms of financing military expansion and brokering deals with strongmen who are able to govern local populations. Finally, to assess how these strategies embody a form of “negotiated statehood” in which the state's growing control has been defined by attempts to manage, rather than monopolize, the means of coercion and extraction