3,199 research outputs found

    Grid Cells Form a Global Representation of Connected Environments.

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    The firing patterns of grid cells in medial entorhinal cortex (mEC) and associated brain areas form triangular arrays that tessellate the environment [1, 2] and maintain constant spatial offsets to each other between environments [3, 4]. These cells are thought to provide an efficient metric for navigation in large-scale space [5-8]. However, an accurate and universal metric requires grid cell firing patterns to uniformly cover the space to be navigated, in contrast to recent demonstrations that environmental features such as boundaries can distort [9-11] and fragment [12] grid patterns. To establish whether grid firing is determined by local environmental cues, or provides a coherent global representation, we recorded mEC grid cells in rats foraging in an environment containing two perceptually identical compartments connected via a corridor. During initial exposures to the multicompartment environment, grid firing patterns were dominated by local environmental cues, replicating between the two compartments. However, with prolonged experience, grid cell firing patterns formed a single, continuous representation that spanned both compartments. Thus, we provide the first evidence that in a complex environment, grid cell firing can form the coherent global pattern necessary for them to act as a metric capable of supporting large-scale spatial navigation

    Intensive Cultural Resources Survey of the 6.6-acre Haden Road Tract, Cloverleaf, Harris County, Texas

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    Horizon Environmental Services, Inc. (Horizon) was selected by Berg-Oliver Associates, Inc. (Berg Oliver) on behalf of Harris County Water Control Improvement District (WCID) No. 36 to conduct a cultural resources inventory survey and assessment for the proposed development of a wastewater treatment facility on the approximately 2.6-hectare (6.6-acre) Haden Road tract in Cloverleaf, Harris County, Texas. The currently undeveloped tract is located southeast of the intersection of Interstate Highway (IH) 10 and Haden Road. An unnamed tributary of Greens Bayou bisects the tract east to west. Based on historic-age aerials and topographic maps, no known development has occurred on the 2.7-hectare (6.6-acre) tract. The proposed project is being sponsored by Harris County WCID No. 36. Funding is being provided through a community development block grant (CDBG) contributed by the Texas General Land Office (GLO). Because the proposed wastewater treatment facility is being sponsored by a public utility and subsidized by a political subdivision of the state of Texas, the project falls under the jurisdiction of the Antiquities Code of Texas (Natural Resources Code, Title 9, Chapter 191). At this time, no federal funding, licenses, or permits are required for the proposed undertaking. However, should any impacts occur to the unnamed tributary of Greens Bayou that flows through the proposed project area, permitting would be required by the US Army Corps of Engineers (USACE) under Section 404 of the Clean Water Act (CWA). In this case, any portions of the overall project area that fall under the federal permit would also fall under the jurisdiction of Section 106 of the National Historic Preservation Act (NHPA) of 1966, as amended. As the project represents a publicly sponsored undertaking with the potential to impact potentially significant cultural resources, the project sponsor was required to perform a cultural resources inventory and assessment of the project area. On July 26, 2017, Horizon staff archeologist Briana Nicole Smith, under the overall direction of Jeffrey D. Owens, Principal Investigator, performed an intensive cultural resources survey of the project area to locate any cultural resources that potentially would be impacted by the proposed undertaking. Horizon’s archeologist traversed the project area on foot and thoroughly inspected the modern ground surface for aboriginal and historic-age cultural resources. In addition to pedestrian walkover, the Texas State Minimum Archeological Survey Standards (TSMASS) require a minimum of 2 shovel tests per acre for tracts between 3.0 and 10.0 acres in size. As such, a minimum of 13 shovel tests would be required within the 2.7- hectare (6.6-acre) project area. Horizon excavated a total of 15 shovel tests, thereby exceeding the TSMASS for a project area of this size. The survey was conducted under Texas Antiquities Permit No. 8115. Shovel testing revealed heavily disturbed artificial deposits of mottled sandy clay and dense clay sediments overlying the native clayey fluviomarine soils at depths of 20.0 to 40.0 centimeters (7.8 to 15.7 inches) below surface. Shovel tests were placed along both banks of the unnamed tributary of Greens Bayou. Ground surface visibility was low to moderate due to dense, ankle- to knee-high wild grasses and weeds, which cover the majority of the project area. The southwestern portion of the tract had less vegetation, allowing for better visibility of the heavily disturbed ground surface. Modern trash was abundant throughout the project area, which appears to be actively used as a dump site, and several shovel tests contained modern trash within the upper 20.0 centimeters. (7.8 inches). The majority of modern trash appears to have been dumped within the tree line that follows the southern boundary of the project area. The northernmost portion of the project area is disturbed from the construction of multiple storm water manholes. Based on the results of the survey-level investigations documented in this report, no potentially significant cultural resources would be affected by the proposed undertaking. In accordance with 36 CFR 800.4, Horizon has made a reasonable and good-faith effort to identify historic properties within the project area. No cultural resources were identified that meet the criteria for designation as SALs according to 13 TAC 26. Horizon recommends a finding of “no historic properties affected,” and no further archeological work is recommended in connection with the proposed undertaking. However, human burials, both prehistoric and historic, are protected under the Texas Health and Safety Code. In the event that any human remains or burial objects are inadvertently discovered at any point during construction, use, or ongoing maintenance in the project area, even in previously surveyed areas, all work should cease immediately in the vicinity of the inadvertent discovery, and the Texas Historical Commission (THC) should be notified immediately

    Intensive Cultural Resources Survey of the 55.4-acre Rosser Quarry Expansion, Scurry, Kaufman County, Texas

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    On August 23, 2017, Horizon Environmental Services, Inc. (Horizon) conducted a cultural resources inventory survey and assessment for the proposed 22.4-hectare (55.4-acre) Rosser Quarry expansion in Scurry, Kaufman County, Texas. The currently undeveloped tract is located west of Rosser, Texas, between the Trinity River, approximately 270.0 meters (885.8 feet) to the west, and the existing Rosser Quarry to the east. Three US Army Corps of Engineer (USACE) jurisdictional “Waters of the US” (WOUS) are present within the southeastern portion of the project area. These consisted of two ephemeral branches of an unnamed tributary of the Trinity River as well as one excavated pond feature. Although the proposed work area would be located on private property and would be privately funded, the proposed impacts to the three jurisdictional water features would require permitting by the USACE under Section 404 of the Clean Water Act (CWA). As this is a federal permit, the proposed construction activities within the USACE jurisdictional areas fall under the jurisdiction of Section 106 of the National Preservation Act (NHPA) of 1966, as amended. Lattimore Materials contracted with Horizon to conduct an intensive cultural resources survey of the proposed project area in compliance with the regulations of Section 106 of the NHPA. The purpose of the survey was to determine if any cultural resources were located within the project area, and, if so, to determine their eligibility for inclusion in the National Register of Historic Places (NRHP). Current USACE guidance calls for conducting cultural resources surveys on the banks and adjacent uplands of WOUSs, which are typically defined as a 100.0-meter (328.0-foot) buffer surrounding of the jurisdictional feature. Thus, for purposes of the current cultural resources survey, the Area of Potential Effect (APE) would be considered to extend 100.0 meters (328.0 feet) surrounding the edges of the three jurisdictional features in the southeastern corner of the overall project area. However, as the physiographic setting of the project area on the floodplain of the Trinity River suggested a high potential for previously undocumented cultural resources, Horizon conducted an intensive cultural resources survey of the entire 55.4-acre (22.4-hectare) project area, including the area immediately surrounding the three jurisdictional water features. Horizon staff archeologists Briana Nicole Smith and Stephanie Mueller, under the overall direction of Jeffrey D. Owens, Principal Investigator, performed an intensive cultural resources survey of the project area on August 23, 2017, to locate any cultural resources that potentially would be impacted by the proposed undertaking. Horizon’s archeologists traversed the project area on foot and thoroughly inspected the modern ground surface for aboriginal and historic-age cultural resources. In addition to pedestrian walkover, the Texas State Minimum Archeological Survey Standards (TSMASS) require a minimum of 1 shovel test per 2.0 acres (0.8 hectare) for tracts between 4.5 and 40.5 hectares (11.0 and 100.0 acres) in size. As such, a minimum of 28 shovel tests would be required within the 22.4-hectare (55.4-acre) project area. Horizon excavated a total of 28 shovel tests, thereby meeting the TSMASS for a project area of this size. In addition, four trenches were excavated using a trackhoe with a 1.8-meter- (6.0-foot-) wide bucket in the vicinity of the USACE jurisdictional tributaries and pond in the southeastern portion of the project area. The trenches were excavated in order to assess the potential for deeply buried cultural resources and the presence of buried paleosols, such as the West Fork paleosol known from farther to the north within the Trinity River basin. Shovel testing revealed dense clay soils that were impenetrable with shovels past an average depth of 30.0 centimeters (11.8 inches) below surface. The four trenches excavated within the southeastern portion of the project area revealed deep alluvial sediments consisting of dense clay overlying sandy clay and sandy clay loam to depths of 5.0 to 5.5 meters (16.4 to 18.0 feet) below surface. Ground surface visibility was low throughout the project area due to dense undergrowth vegetation that has developed subsequent to past vegetation-clearing events. Tall ragweed, greenbrier, and poison ivy covered the majority of the project area as well as occasional clusters of mesquite, oak, and cottonwood trees. No cultural resources, prehistoric or historic-age, were documented on the modern ground surface or within any of the shovel tests or trackhoe trenches excavated within the project area. Furthermore, no evidence of subsurface paleosols was observed in any of the four trackhoe trenches. While shovel testing was not capable of fully penetrating Holocene-age floodplain deposits within the broader project area, all of the deep, clayey alluvial deposits observed in the four trackhoe trenches were culturally sterile, and the stratigraphy observed in trench wall profiles did not suggest any clear boundaries between strata that suggest that stabilized land surfaces were present for any prolonged period of time during the accretion of the floodplain alluvial fills. Based on the results of the survey-level investigations documented in this report, no potentially significant cultural resources would be affected by the proposed undertaking. In accordance with 36 CFR 800.4, Horizon has made a reasonable and good faith effort to identify historic properties within the APE and broader project area. No cultural resources were identified that meet the criteria for listing on the National Register of Historic Places (NRHP) according to 36 CFR 60.4. Horizon recommends a finding of “no historic properties affected,” and no further archeological work is recommended in connection with the proposed undertaking. However, in the event that any human remains or burial objects are inadvertently discovered at any point during construction, use, or ongoing maintenance in the project area, even in previously surveyed areas, all work should cease immediately and the Texas Historical Commission (THC) and/or the USACE, as appropriate, should be notified of the discovery

    An analysis of ultraviolet spectra of Extreme Helium Stars and new clues to their origins

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    Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD+10 2179, V1920 Cyg, HD 124448, PV Tel, LS IV -1 2, and FQ Aqr. New optical spectra of the three stars -- BD+10 2179, V1920 Cyg, and HD 124448 were analysed. The abundance analyses is done using LTE line formation and LTE model atmospheres especially constructed for these EHe stars. The stellar parameters derived from an EHe's UV spectrum are in satisfactory agreement with those derived from its optical spectrum. Adopted abundances for the seven EHes are from a combination of the UV and optical analyses. Published results for an additional ten EHes provide abundances obtained in a nearly uniform manner for a total of 17 EHes, the largest sample on record. The initial metallicity of an EHe is indicated by the abundance of elements from Al to Ni; Fe is adopted to be the representative of initial metallicity. Iron abundances range from approximately solar to about one-hundredth of solar. Clues to EHe evolution are contained within the H, He, C, N, O, Y, and Zr abundances. Two novel results are (i) the O abundance for some stars is close to the predicted initial abundance yet the N abundance indicates almost complete conversion of initial C, N, and O to N by the CNO-cycles; (ii) three of the seven stars with UV spectra show a strong enhancement of Y and Zr attributable to an s-process. The observed compositions are discussed in light of expectations from accretion of a He white dwarf by a CO white dwarf.Comment: 126 pages, 15 figures, 20 Tables, accepted for publication in the Ap

    A realistic double many-body expansion potential energy surface for from a multiproperty fit to accurate ab initio energies and vibrational levels

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    A single-valued double many-body expansion potential energy surface (DMBE I) recently obtained for the ground electronic state of the sulfur dioxide molecule by fitting correlated ab initio energies suitably corrected by scaling the dynamical correlation energy is now refined by fitting simultaneously available spectroscopic levels up to 6886 cm-1 above the minimum. The topographical features of the novel potential energy surface (DMBE II) are examined in detail, and the method is emphasized as a robust route to fit together state-of-the-art theoretical calculations and spectroscopic measurements using a single fully dimensional potential form.http://www.sciencedirect.com/science/article/B6VNG-44JJ0TT-5/1/c39f816ff06826dc517ad62441e91b5

    The Hot R Coronae Borealis Star DY Centauri is a Binary

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    The remarkable hot R Coronae Borealis (RCB) star DY Cen is revealed to be the first and only binary system to be found among the RCB stars and their likely relatives, including the extreme helium stars and the hydrogen-deficient carbon stars. Radial velocity determinations from 1982 to 2010 have shown that DY Cen is a single-lined spectroscopic binary in an eccentric orbit with a period of 39.67 days. It is also one of the hottest and most H-rich member of the class of RCB stars. The system may have evolved from a common envelope to its current form.Spanish Ministry of Economy and Competitiveness AYA-2011-27754McDonald Observator

    Dogs with macroadenomas have lower body temperature and heart rate than dogs with microadenomas

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    Pituitary macroadenomas compress the hypothalamus, which partly regulates heart rate and body temperature. The aim of this study was to investigate whether heart rate and/or body temperature could aid in clinically differentiating dogs with macroadenomas from dogs with microadenomas (i.e. small non-compressive pituitary mass). Two groups of dogs diagnosed with pituitary-dependent hyperadrenocorticism (i.e. Cushing’s disease) were included. Heart rate and body temperature were collected on initial presentation before any procedure. Dogs with macroadenoma had a significantly lower heart rate and body temperature (P < 0.01) compared to dogs with microadenoma. We suggest that the combined cut-off values of 84 beats per minutes and 38.3 °C in dogs with Cushing’s disease, especially with vague neurological signs (nine of 12 dogs = 75%), might help to suspect the presence of a macroadenoma

    Childhood obesity: Evidence for distinct early and late environmental determinants a 12-year longitudinal cohort study (EarlyBird 62)

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    Background/objective:The prevalence of childhood obesity continues to rise in most countries, but the exposures responsible remain unclear. The shape of the body mass index (BMI) distribution curve defines how a population responds, and can be described by its three parameters-skew (L), median (M) and variance (S). We used LMS analysis to explore differences in the BMI trajectories of contemporary UK children with those of 25 years ago, and to draw inferences on the exposures responsible.Subjects/methods:We applied Cole's LMS method to compare the BMI trajectories of 307 UK children (EarlyBird cohort) measured annually from 5-16 years (2000-2012) with those of the BMI data set used to construct the UK 1990 growth centiles, and used group-based trajectory modelling (GBTM) to establish whether categorical trajectories emerged.Results:Gender-specific birth weights were normally distributed and similar between both data sets. The skew and variance established by 5 years in the 1990 children remained stable during the remainder of their childhood, but the pattern was different for children 25 years on. The skew at 5 years among the EarlyBird children was greatly exaggerated, and involved selectively the offspring of obese parents, but returned to 1990 levels by puberty. As the skew diminished, so the variance in BMI rose sharply. The median BMI of the EarlyBird children differed little from that of 1990 before puberty, but diverged from it as the variance rose. GBTM uncovered four groups with distinct trajectories, which were related to parental obesity.Conclusions:There appear to be two distinct environmental interactions with body mass among contemporary children, the one operating selectively according to parental BMI during early childhood, the second more generally in puberty.Bright Future TrustBUPA FoundationPeninsula FoundationKirby Laing TrustEarlyBird Diabetes Trus
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