Searching at the right time of day: Evidence for aqueous minerals in Columbus crater with TES and THEMIS data

The primary objective of the Thermal Emission Imaging System (THEMIS) experiment, which has been in orbit at Mars since early 2002, is to identify minerals associated with hydrothermal and subaqueous environments. Data from THEMIS have supported the presence of clays, silica-rich deposits, and chlorides but has not before provided definitive evidence for the presence of sulfates. This is an especially puzzling result given that sulfates have been extensively identified with other instruments at Mars. If present, sufficiently exposed, and in high enough abundances, such minerals should be detectable in orbital thermal infrared spectra at the resolution of THEMIS. The extended mission proposal for THEMIS on Mars Odyssey suggests that the detection of all minerals may be enhanced by observing at an earlier time of day and thus at warmer temperatures. Therefore, in 2009, Odyssey moved to an earlier orbit time. Here, we examine THEMIS data collected when the earlier orbit time coincided with the Martian local (southern) late summer (Ls = 270) for Columbus crater where Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data have detected a number of aqueous minerals. Some of the warmest THEMIS images show evidence for aqueous minerals, although not in the same locations where CRISM finds the highest concentrations. Several factors contribute to this result, including differences in the diurnal temperature curve and levels of induration and particle size. For THEMIS, earlier time-of-day and proper seasonal observations combine to provide warm surface temperatures and ideal low atmospheric opacity that significantly increases the ability to definitively identify low spectral contrast aqueous minerals at the surface of Mars

Constructions of generalized complex structures in dimension four

Four-manifold theory is employed to study the existence of (twisted) generalized complex structures. It is shown that there exist (twisted) generalized complex structures that have more than one type change loci. In an example-driven fashion, (twisted) generalized complex structures are constructed on a myriad of four-manifolds, both simply and non-simply connected, which are neither complex nor symplectic

Assessing the Accuracy of Respondents Reports of the Location of Their Home Relative to a National Forest Boundary and Forest Cover

This paper assesses the accuracy of responses to a question that asks the location of respondents’ homes relative to a National Forest boundary. The analysis also assesses the accuracy of respondent reports on forest cover in the area surrounding their home. We find non-ignorable error in the responses to both questions. The remainder of this paper is divided into three sections. First, the methods used for this study are described as are limitations of the study. Second, we illustrate the study’s results. Finally, we discuss our results and conclusions

Inoculation studies related to breeding for resistance to bacterial wilt in lespedeza

... cooperative investigation between the Department of Field Crops, Missouri Agricultural Experiment Station, University of Missouri, and Forage and Range Section, Field Crops Branch, Agricultural Research Service, U.S. Department of Agriculture...--P. [2].Digitized 2007 AES.Includes bibliographical references (page 47)

Exotic smooth structures on 4-manifolds with zero signature

For every integer $k\geq 2$, we construct infinite families of mutually nondiffeomorphic irreducible smooth structures on the topological $4$-manifolds $(2k-1)(S^2\times S^2)$ and (2k-1)(\CP#\CPb), the connected sums of $2k-1$ copies of $S^2\times S^2$ and \CP#\CPb.Comment: 6 page

Rickettsial ompB Promoter Regulated Expression of GFPuv in Transformed Rickettsia montanensis

Background: Rickettsia spp. (Rickettsiales: Rickettsiaceae) are Gram-negative, obligate intracellular, a-proteobacteria that have historically been associated with blood-feeding arthropods. Certain species cause typhus and spotted fevers in humans, but others are of uncertain pathogenicity or may be strict arthropod endosymbionts. Genetic manipulation of rickettsiae should facilitate a better understanding of their interactions with hosts. Methodology/Principal Findings: We transformed a species never associated with human disease, Rickettsia montanensis, by electroporation with a TN5 transposon (pMOD700) containing green fluorescent protein (GFPuv) and chloramphenicol acetyltransferase (CAT) genes under regulation of promoters cloned from the Rickettsia rickettsii ompB gene, and isolated a Chloramphenicol-resistant GFP-fluorescent rickettsiae population (Rmontanensis700). The Rmontanensis700 rickettsiae contained a single transposon integrated near an acetyl-CoA acetyltransferase gene in the rickettsial chromosome. Northern blots showed that GFPuv and CAT mRNAs were both expressed as two transcripts of larger and smaller than predicted length. Western immunoblots showed that Rmontanensis700 and E. coli transformed with a plasmid containing the pMOD700 transposon both expressed GFPuv proteins of the predicted molecular weight. Conclusions/Significance: Long-standing barriers to transformation of rickettsiae have been overcome by development of transposon-based rickettsial transformation vectors. The ompB promoter may be the most problematic of the fou

Development of Shuttle Vectors for Transformation of Diverse Rickettsia Species

Plasmids have been identified in most species of Rickettsia examined, with some species maintaining multiple different plasmids. Three distinct plasmids were demonstrated in Rickettsia amblyommii AaR/SC by Southern analysis using plasmid specific probes. Copy numbers of pRAM18, pRAM23 and pRAM32 per chromosome in AaR/SC were estimated by real-time PCR to be 2.0, 1.9 and 1.3 respectively. Cloning and sequencing of R. amblyommii AaR/SC plasmids provided an opportunity to develop shuttle vectors for transformation of rickettsiae. A selection cassette encoding rifampin resistance and a fluorescent marker was inserted into pRAM18 yielding a 27.6 kbp recombinant plasmid, pRAM18/Rif/GFPuv. Electroporation of Rickettsia parkeri and Rickettsia bellii with pRAM18/Rif/GFPuv yielded GFPuv-expressing rickettsiae within 2 weeks. Smaller vectors, pRAM18dRG, pRAM18dRGA and pRAM32dRGA each bearing the same selection cassette, were made by moving the parA and dnaA-like genes from pRAM18 or pRAM32 into a vector backbone. R. bellii maintained the highest numbers of pRAM18dRGA (13.3 – 28.1 copies), and R. parkeri, Rickettsia monacensis and Rickettsia montanensis contained 9.9, 5.5 and 7.5 copies respectively. The same species transformed with pRAM32dRGA maintained 2.6, 2.5, 3.2 and 3.6 copies. pRM, the plasmid native to R. monacensis, was still present in shuttle vector transformed R. monacensis at a level similar to that found in wild type R. monacensis after 15 subcultures. Stable transformation of diverse rickettsiae was achieved with a shuttle vector system based on R. amblyommii plasmids pRAM18 and pRAM32, providing a new research tool that will greatly facilitate genetic and biological studies of rickettsiae

Solvent Based 3D Printing of Biopolymer/Bioactive Glass Composite and Hydrogel for Tissue Engineering Applications

Three-dimensional (3D) bioprinting is an emerging technology in which scaffolding materials and cell-laden hydrogels may be deposited in a pre-determined fashion to create 3D porous constructs. A major challenge in 3D bioprinting is the slow degradation of melt deposited biopolymer. In this paper, we describe a new method for printing poly-caprolactone (PCL)/bioactive borate glass composite as a scaffolding material and Pluronic F127 hydrogel as a cell suspension medium. Bioactive borate glass was added to a mixture of PCL and organic solvent to make an extrudable paste using one syringe while hydrogel was extruded and deposited in between the PCL/borate glass filaments using a second syringe. The degradation of the PCL/borate glass composite scaffold with and without the presence of hydrogel was investigated by soaking the scaffold in minimum essential medium. The weight loss of the scaffold together with formation of a hydroxyapatite-like layer on the surface shows the excellent bioactivity of the scaffold

Establishment of a Replicating Plasmid in Rickettsia prowazekii

Rickettsia prowazekii, the causative agent of epidemic typhus, grows only within the cytosol of eukaryotic host cells. This obligate intracellular lifestyle has restricted the genetic analysis of this pathogen and critical tools, such as replicating plasmid vectors, have not been developed for this species. Although replicating plasmids have not been reported in R. prowazekii, the existence of well-characterized plasmids in several less pathogenic rickettsial species provides an opportunity to expand the genetic systems available for the study of this human pathogen. Competent R. prowazekii were transformed with pRAM18dRGA, a 10.3 kb vector derived from pRAM18 of R. amblyommii. A plasmid-containing population of R. prowazekii was obtained following growth under antibiotic selection, and the rickettsial plasmid was maintained extrachromosomally throughout multiple passages. The transformant population exhibited a generation time comparable to that of the wild type strain with a copy number of approximately 1 plasmid per rickettsia. These results demonstrate for the first time that a plasmid can be maintained in R. prowazekii, providing an important genetic tool for the study of this obligate intracellular pathogen