The Carboxyl-Terminal Segment of Apolipoprotein A-V Undergoes a Lipid-Induced Conformational Change

Apolipoprotein (apo) A-V is a 343-residue, multidomain protein that plays an important role in regulation of plasma triglyceride homeostasis. Primary sequence analysis revealed a unique tetraproline sequence (Pro293-Pro296) near the carboxyl terminus of the protein. A peptide corresponding to the 48-residue segment beyond the tetraproline motif was generated from a recombinant apoA-V precursor wherein Pro295 was replaced by Met. Cyanogen bromide cleavage of the precursor protein, followed by negative affinity chromatography, yielded a purified peptide. Nondenaturing polyacrylamide gel electrophoresis verified that apoA-V(296-343) solubilizes phospholipid vesicles, forming a relatively heterogeneous population of reconstituted high-density lipoprotein with Stokes’ diameters\u3e17 nm. At the same time, apoA-V(296-343) failed to bind a spherical lipoprotein substrate in vitro. Far-UV circular dichroism spectroscopy revealed the peptide is unstructured in buffer yet adopts significant R-helical secondary structure in the presence of the lipid mimetic solvent trifluoroethanol (TFE; 50% v/v). Heteronuclear multidemensional NMR spectroscopy experiments were conducted with uniformly 15N- and 15N/13C-labeled peptide in 50% TFE. Peptide backbone assignment and secondary structure prediction using TALOSþ reveal the peptide adopts R-helix secondary structure from residues 309 to 334. In TFE, apoA-V(296-343) adopts an extended amphipathic R-helix, consistent with a role in lipoprotein binding as a component of full-length apoA-V

Archaeological Testing of Four Sites on Camp Bowie, Brown County, Texas

In August of 2002, a crew from the Center for Archaeological Research (CAR) of The University of Texas at San Antonio tested four sites at Camp Bowie in Brown County Texas. Three sites, 41BR471, 41BR500, and 41BR522, were prehistoric and one site, 41BR392, had both historic and prehistoric components. This work was done under Texas Antiquities Permit No. 2926 for the Adjutant General’s Department of Texas. Testing at these sites was done based on recommendations made for 41BR500 by Mauldin and Broehm (2001) and recommendations made for 41BR392, 41BR471 and 41BR522 by Greaves (2002). Testing at 41BR392 centered on a prehistoric burned rock midden. Excavations took place in and around the midden. A few bifaces and a considerable amount of lithic debris were recovered. The size, location and density of burned rock within the midden were examined as a means of investigating the internal midden structure. Analysis of these data suggest that the midden represents an earth oven. Ethnobotanical recovery revealed the presence of geophytes. Radiocarbon dates place the feature within the Late Prehistoric period. Testing at 41BR471 involved surface collection and excavation. Excavations confirmed that the site is deflated with sub-surface deposits being shallow and very minor. What remains of this site is a moderate to dense surface scatter of unmodified debitage and a few lithic cores. Testing at 41BR500 centered on a suspected buried burned rock feature discovered during the spring 2001 survey. Excavations recovered unmodified lithic debitage, biface fragments and a scraper. Excavations in a separate area of the site where high debitage density was noted recovered a Nolan dart point dating to the Middle Archaic along with a number of bifaces and a considerable amount of unmodified lithic debitage. This additional testing uncovered a single charcoal stain, and radiocarbon dates place this feature within the Late Prehistoric period. Our analysis of the distribution of the diagnostic points, the distribution of debitage, and the radiocarbon date, suggest that much of this material is in secondary context. Test excavations at 41BR522 showed very little debitage in or around the prehistoric burned rock midden. This small midden is nearly a perfect ring of burned rock surrounding a central hearth depression. Preservation was excellent for the recovery of both charred botanical remains and for examination of the midden structure. A Montell dart point, dating to the Late Archaic was recovered. As with 41BR392, the size, location and density of burned rock within the midden was examined as a means of investigating the internal midden structure. Analysis revealed the midden to be a central hearth/earth-oven type burned rock midden. Ethnobotanical recovery revealed the presence of geophytes. Radiocarbon dates place the feature within the Late Prehistoric period. Based on the results of this testing, it is recommended that sites 41BR471 and 41BR500 are not eligible to the National Register of Historic Places and do not warrant status as State Archeological Landmarks. The sites have data that are of questionable integrity, and CAR’s testing work has effectively exhausted any remaining research potential. Sites 41BR392 and 41BR522 are recommended as eligible to the National Register of Historic Places and do warrant status as State Archeological Landmarks. Both recommended sites have data with good integrity. In addition, both sites have charcoal present, and good recovery of ethnobotanical material. Data from these sites can be used to consider a variety of research questions that are significant for understanding the prehistory of the region

An investigation of South Pole HOx chemistry: Comparison of model results with ISCAT observations

Unexpected high levels of OH and NO were recorded at the South Pole (SP) Atmospheric Research Observatory during the 1998-99 ISCAT field study. Model simulations suggest a major photochemical linkage between observed OH and NO. A detailed comparison of the observations with model predictions revealed good agreement for OH at NO levels between 120 and 380 pptv. However, the model tended to overestimate OH for NO levels < 120 pptv, while it underestimated OH at levels > 380 pptv. The reasons for these deviations appear not to involve NO directly but rather HOx radical scavenging for the low NO conditions and additional HOx sources for the high NO conditions. Because of the elevated levels of NO and highly activated HOx photochemistry, the SP was found to be a strong net source of surface ozone. It is quite likely that the strong oxidizing environment found at the South Pole extends over the entire polar plateau

Measurements of pernitric acid at the South Pole during ISCAT 2000

The first measurements of pernitric acid at the South Pole were performed during the second Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT 2000). Observed HO2NO2 concentrations averaged 25 pptv. Simple steady-state calculations constrained by measurements show that the lifetime of pernitric acid was largely controlled by dry deposition, with thermal decomposition becoming increasingly important at warmer temperatures. We determined that the pernitric acid equilibrium constant is less uncertain than indicated in the literature. One consequence of pernitric acid deposition to the snow surface is that it is an important sink for both NOx and HOx. Another is that the photochemistry of HO2NO2 in the Antarctic snowpack may be a NOx source in addition to nitrate photolysis. This might be one of the important differences in snow photochemistry between the South Pole and warmer polar sites

Higher-dimensional multifractal value sets for conformal infinite graph directed Markov systems

We give a description of the level sets in the higher dimensional multifractal formalism for infinite conformal graph directed Markov systems. If these systems possess a certain degree of regularity this description is complete in the sense that we identify all values with non-empty level sets and determine their Hausdorff dimension. This result is also partially new for the finite alphabet case.Comment: 20 pages, 1 figur

LunaNet: a Flexible and Extensible Lunar Exploration Communications and Navigation Infrastructure

NASA has set the ambitious goal of establishing a sustainable human presence on the Moon. Diverse commercial and international partners are engaged in this effort to catalyze scientific discovery, lunar resource utilization and economic development on both the Earth and at the Moon. Lunar development will serve as a critical proving ground for deeper exploration into the solar system. Space communications and navigation infrastructure will play an integral part in realizing this goal. This paper provides a high-level description of an extensible and scalable lunar communications and navigation architecture, known as LunaNet. LunaNet is a services network to enable lunar operations. Three LunaNet service types are defined: networking services, position, navigation and timing services, and science utilization services. The LunaNet architecture encompasses a wide variety of topology implementations, including surface and orbiting provider nodes. In this paper several systems engineering considerations within the service architecture are highlighted. Additionally, several alternative LunaNet instantiations are presented. Extensibility of the LunaNet architecture to the solar system internet is discussed

Camp Maxey IV Archaeological Testing of Six Sites, Lamar County, Texas

From June 14 through July 4, 2001, the Center for Archaeological Research of The University of Texas at San Antonio conducted National Register of Historic Places eligibility testing of six prehistoric archaeological sites (41LR190, 41LR194, 41LR196, 41LR200, 41LR258, and 41LR259) at Camp Maxey, Lamar County, Texas, under contract with the Texas Army National Guard. The investigations were conducted under Texas Antiquities Permit No. 2180. The Phase II testing fieldwork consisted of the excavation of twelve backhoe trenches and nineteen 1 x 1-m test units across the sites to investigate significant cultural deposits encountered during the previous survey phase. In concert with the archaeological field investigations, lithic and native ceramic analyses and magnetic sediment susceptibility studies were performed to aid in the determination of site integrity and eligibility. The synthesis of these analyses has provided adequate data to determine temporal integrity and recommendation of National Register eligibility for site 41LR190. Further cultural resources investigations in the form of Phase III data recovery excavations are thus recommended for this site prior to proposed development. Conversely, due to lack of significance criteria, sites 41LR194, 41LR196, 41LR200, 41LR258, and 41LR259 are recommended as ineligible for inclusion in the National Register and require no further cultural resources investigations

Results of Archeological Significance Testing at 41TV410 and 41TV540 and Associated Geomorphological Investigations on a Segment of Onion Creek in Travis County, Texas

In late 2005, the Texas Department of Transportation (TxDOT) contracted the Center for Archaeological Research at the University of Texas at San Antonio (CAR-UTSA) to conduct significance testing at 41TV410 and 41TV540, two prehistoric archeological sites located in the floodplain of Onion Creek in southeast Austin in Travis County. The work was conducted in advance of a borrow pit excavation related to the construction on State Highway (SH) 130. The borrow pit represented a project specific location (PSL). PSLs are normally not part of the project per Federal Highway Administration policy. PSLs are the responsibility of the contractor in most cases. However, the testing reported here was mandated by language of the SH 130 comprehensive development agreement. Significance testing was performed late in 2005 and early in 2006. For 41TV540, Dr. Raymond Mauldin served as Principal Investigator and Jennifer Thompson served as the Project Archeologist. At 41TV410, Dr. Mauldin served as Project Archeologist and Dr. Steve Tomka served as Principal Investigator. The archeological work at these sites was not under the purview of either Section 106 or the Antiquities Code of Texas. The work was not conducted under a Texas Antiquities Permit. However, testing at both sites was conducted in accordance with the Secretary of the Interior’s Standards and Guidelines for Archeology and Historic Preservation and guidelines provided by the Texas Historical Commission (THC). CAR completed fieldwork in early January of 2006. At 41TV410, 11 features were uncovered with radiocarbon dates that fell in the Early/Middle Archaic and in the Late Archaic. Recovery of artifacts and ecofacts was extremely low. The 41TV540 work also produced a low density of chipped stone artifacts and tools, and exposed 17 features, many of which dated to the close of the Early Archaic. Preliminary observations on flotation returns suggested good quantities of burned material and faunal remains were present at 41TV540. CAR prepared post-field reports summarizing the work and provided recommendations for both sites. Because both locations appeared to contain intact deposits that could, in our view, contribute to an understanding of the prehistoric cultural development of the region, CAR recommended that the sites were eligible to the NRHP under criterion d. TxDOT agreed with CAR recommendations that 41TV540 was eligible for listing in the NRHP, though they did not request any additional work at the site. TxDOT concluded that site 41TV410 was not eligible for listing on the NRHP. At TxDOT’s instruction, CAR prepared a research design for the analysis of the testing data from 41TV540, as well as a summary of the 41TV410 work. That document (Tomka et al. 2007), which outlined a series of analyses including several new geomorphic studies and a project area geomorphic synthesis, served as a guideline for the present document. Since the archeological and geomorphological investigations reported here, the construction of SH 130 has been completed and deposits containing the sites discussed have been removed. All artifacts, notes, photos, and other material associated with the project are stored at CAR. At this time, decisions regarding the disposal of selected artifact classes, as well as the location for permanent curation of the remaining artifacts and associated records, have not been made. However, it is expected that all project related records and artifacts retained will be permanently curated at CAR