bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of dopamine on pulmonary diffusing capacity and capillary blood volume responses to exercise in young healthy humans
Authors: Michaelchuk Wade W. , Tedjasaputra Vincent , Bryan Tracey L. , van Diepen Sean , Stickland Michael K. 
Published: October 2019

New Findings
What is the Central question?
Does dopamine, a pulmonary vascular vasodilator, contribute to the regulation of pulmonary diffusing capacity and capillary blood volume responses to exercise and exercise tolerance?

What are the main findings and their importance?
Dopamine appears not to be important for regulating pulmonary diffusing capacity or pulmonary capillary blood volume during exercise in healthy participants. Dopamine blockade trials demonstrated that endogenous dopamine is important for maintaining exercise tolerance; however, exogenous dopamine does not improve exercise tolerance.

AbstractPulmonary capillary blood volume (Vc) and diffusing membrane capacity (Dm) expansion are important contributors to the increased pulmonary diffusing capacity (DLCO) observed during upright exercise. Dopamine is a pulmonary vascular vasodilator, and recent studies suggest that it may play a role in Vc regulation through changes in pulmonary vascular tone. The purpose of this study was to examine the effect of exogenous dopamine and dopamine receptor‐2 (D2‐receptor) blockade on DLCO, Vc and Dm at baseline and during cycle exercise, as well as time‐to‐exhaustion at 85% of . We hypothesized that dopamine would increase DLCO, Vc, Dm and time‐to‐exhaustion, while D2‐receptor blockade would have the opposite effect. We recruited 14 young, healthy, recreationally active subjects ( 45.8 ± 6.6 ml kg−1 min−1). DLCO, Vc and Dm were determined at baseline and during exercise at 60% and 85% of under the following randomly assigned and double blinded conditions: (1) intravenous saline and placebo pill, (2) intravenous dopamine (2 µg kg−1 min−1) and placebo pill, and (3) intravenous saline and D2‐receptor antagonist (20 mg oral metoclopramide). Exogenous dopamine and dopamine blockade had no effect on DLCO, Vc and Dm responses at baseline or during exercise. Dopamine blockade reduced time‐to‐exhaustion by 47% (P = 0.04), but intravenous dopamine did not improve time‐to‐exhaustion. While dopamine modulation did not affect DLCO, Vc or Dm, the reduction in time‐to‐exhaustion with D2‐receptor blockade suggests that endogenous dopamine is important for exercise tolerance.
Students’ Knowledge and Behaviors for Active Living: A Cross-Sectional Survey Study
Authors: Liu Yang , Chen Senlin 
Published: October 2019

Purpose: The purpose of this study is to capture students’ essential knowledge and behaviors concerning active living. Methods: Students (N = 1,079) from elementary, middle, and high schools in the United States reported their knowledge of physical activity and fitness (PAF knowledge), and physical activity and sedentary behavior using grade-specific PE Metrics tests and Youth Activity Profile, respectively. Descriptive and inferential statistical analyses were used to address the research purposes. Results: The total PAF knowledge scores and scores in subareas varied by gender and school level. A declining trend for physical activity and an increasing trend for sedentary behavior were observed. PAF knowledge positively predicted physical activity in elementary school boys and middle school girls and negatively predicted sedentary behavior in middle school students and high school boys. Certain PAF knowledge subareas (e.g., elementary school PD#3: knowledge about the characteristics of health-enhancing physical activity; middle school PD#1: knowledge of physical activity participation as part of a healthful lifestyle; high school PD#4: monitoring and adjusting physical activity to meet fitness needs) also significantly predicted behaviors. Conclusion: The findings may guide teachers’ curricular and instructional actions to enhance students’ PAF knowledge through physical education.
Eruption and emplacement dynamics of coarse-grained, wall rock–rich beds in the Keanakāko‘i Tephra, Kīlauea, Hawai‘i
Authors: Isgett* Samantha J. , Houghton Bruce F. , Swanson Donald A. 
Published: October 2019

ABSTRACT
A series of coarse-grained, relatively well-sorted, but wall rock–rich pyroclastic deposits within Unit H of the Keanakāko‘i deposits at Kīlauea Volcano, Hawai‘i, is the focus of this study. These “c” subunits within Unit H consist of alternations between very coarse and relatively well-sorted pyroclastic fall deposits and products of relatively concentrated pyroclastic density currents. They are associated with both accretionary lapilli–bearing ash falls (a beds) and cross-bedded, fine-grained pyroclastic density current deposits (b beds). The Unit H sequence is related to phreatomagmatic explosions from multiple sources in the modern caldera, and we infer that most vents for the c subunits were located near the southern part of the caldera. The c beds contain varying proportions of dense, outgassed juvenile bombs and hydrothermally altered wall rock that suggest, along with coarser grain size and good sorting, that fragmentation conditions were relatively dry for phreatomagmatic eruptions and were perhaps aided by the release of magmatic gases from a deep magma source. The c fall subunits, with thinning half distances of 200–300 m, are more widely dispersed than both the most powerful Hawaiian fountaining eruptions and the well-documented historical explosive eruptions at Kīlauea, with proximal dispersal rates similar to historical subplinian eruptions at other volcanoes. The c pyroclastic density currents were erosive and of a style that represents a threat that is underrated at Kīlauea.
Uvalde Pool of the Edwards (Balcones Fault Zone) Aquifer
Authors: Green R.T. , Bertetti F.P. , Fratesi B. , McGinnis R.N. 
Published: October 2019

ABSTRACT
The Uvalde Pool comprises the western portion of the San Antonio segment of the Edwards (Balcones Fault Zone) Aquifer. Assessment of available data on the hydrogeology of Uvalde County confirms the conceptualization that the Edwards Aquifer in Uvalde County to the west of the city of Knippa acts as a partially separate groundwater basin. This portion of the Edwards Aquifer is referred to as the Uvalde Pool. The Edwards Aquifer to the east of the Uvalde Pool is referred to as the San Antonio Pool. A constriction in groundwater flow between the two pools, referred to as the Knippa Gap, and marked differences in groundwater elevations on either side of the Knippa Gap are the motivation to treat the Uvalde and San Antonio Pools as separate hydrogeological features. The Uvalde Pool is unique because it is the only place where the Edwards Aquifer is in hydraulic communication with the overlying and younger Buda Limestone and the Austin Chalk Aquifers. Given the karstic nature of the Edwards Aquifer in the Uvalde Pool and its relatively limited spatial extent, the Uvalde Pool is characterized as a highly transmissive aquifer, but with relatively limited storage capacity.
Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer, central Texas
Authors: Hunt Brian B. , Smith Brian A. , Hauwert Nico M. 
Published: October 2019

ABSTRACT
The Barton Springs segment of the Edwards (Balcones Fault Zone) Aquifer is a prolific karst aquifer system containing the fourth largest spring in Texas, Barton Springs. The Barton Springs segment of the Edwards Aquifer supplies drinking water for ~60,000 people, provides habitat for federally listed endangered salamanders, and sustains the iconic recreational Barton Springs pool. The aquifer is composed of Lower Cretaceous carbonate strata with porosity and permeability controlled by depositional facies, diagenesis, structure, and karstification creating a triple permeability system (matrix, fractures, and conduits). Groundwater flow is rapid within an integrated network of conduits discharging at the springs. Upgradient watersheds provide runoff to the recharge zone, and the majority of recharge occurs in the streams crossing the recharge zone. The remainder is direct recharge from precipitation and other minor sources (inflows from Trinity Group aquifers, the San Antonio segment, the bad-water zone, and anthropogenic sources). The long-term estimated mean water budget is 68 ft3/s (1.93 m3/s). The Barton Springs/Edwards Aquifer Conservation District developed rules to preserve groundwater supplies and maximize spring flow rates by preserving at least 6.5 ft3/s (0.18 m3/s) of spring flow during extreme drought. A paradox of the Barton Springs segment of the Edwards Aquifer is that rapid recharge allows the Barton Springs segment of the aquifer to be sustainable long term, but the aquifer is vulnerable and limited in droughts. The karstic nature of the aquifer makes the Barton Springs segment vulnerable to a variety of natural and anthropogenic contaminants. Future challenges will include maintaining the sustainability of the aquifer, considering climate change, population growth, and related land-use changes.
The Edwards-Trinity (Plateau) and Trinity (Hill Country) Aquifer System, Texas
Authors: Jones Ian C. , Anaya Roberto 
Published: October 2019

ABSTRACT
The groundwater flow system composed of the Edwards-Trinity (Plateau) Aquifer and the Hill Country portion of the Trinity Aquifer together occupy an area of ~100,000 km2 of west-central Texas. In addition to the common groundwater flow system, these aquifers also share a common, contiguous hydrostratigraphy—the Trinity Group hydrostratigraphic unit. The aquifers provide the primary source of water for the Edwards Plateau and Texas Hill Country and also sustain numerous springs and streams in the region. The sensitivity of the aquifers to drought and well discharge has raised concerns over the availability of water from these aquifers.
Groundwater discharge takes the form of (1) discharge to streams and springs; (2) evapotranspiration; (3) pumpage from wells; and (4) cross-formational flow across the Balcones fault zone boundary to the Edwards (Balcones Fault Zone) Aquifer and underlying parts of the Trinity Aquifer. Groundwater inflow to these aquifers occurs by diffuse and discrete infiltration through the aquifer outcrops. Due to regional variability of lithologic compositions, hydraulic conductivity and storativity vary both vertically and laterally throughout the aquifer, with hydraulic conductivity decreasing with depth and from north to south.
Effects of urbanization on the Edwards Aquifer
Authors: Sharp John M. 
Published: October 2019

ABSTRACT
The Edwards Aquifer along the Balcones fault zone is in a rapidly growing, urbanizing area. Urbanization creates major hydrogeological impacts, generally increasing impervious cover and flooding intensity, water demands, groundwater recharge, and temperatures both above and below the land surface; covering springs and small streams; altering the porosity and permeability fields; and contaminating groundwater, surface water, and soils. Urbanization also alters topography, natural flora, and the local climate. Several of these effects have either been documented or predicted for the Edwards Aquifer. Groundwater recharge from leaky utility systems and irrigation return flow is significant, particularly during times of low rainfall. The hydraulic properties of the epikarst, particularly the permeability field, can be highly modified. Aquifer water quality remains excellent, but increased anthropogenic chemical nitrate and chloride concentrations, and occasional bacteriological contamination have been observed. The eventual effects of these changes on the aquifers’ unique ecosystems is not known.
Urbanization and urban sprawl are projected to increase, which will continue to alter the Edwards Aquifer system physically, chemically, and biologically. Understanding of these changes, their causes, and their effects is necessary to addressing the critical and growing environmental and water-resources issues of urban areas in the coming century.
Emerging contaminants in groundwater, karst, and the Edwards (Balcones Fault Zone) Aquifer
Authors: Mahler Barbara , Musgrove MaryLynn 
Published: October 2019

ABSTRACT
Karst aquifers have hydrogeologic characteristics that render them uniquely vulnerable to contamination from emerging contaminants (ECs). ECs comprise numerous chemical groups, including pharmaceuticals, personal-care products, flame retardants, perfluorinated and polyfluorinated compounds, nanoparticles, and microplastics. Many ECs have sources, transport pathways, and chemical characteristics that facilitate their infiltration into groundwater, either indirectly from surface water or directly from sources such as landfill leachate and septic systems. What little is known about the occurrence, fate, and transport of ECs in the Edwards (Balcones Fault Zone) Aquifer indicates that the aquifer might be increasingly vulnerable to this type of contamination. The natural physical characteristics of this karst aquifer and anthropogenic sources of ECs associated with increased urbanization in central Texas contribute to this vulnerability. In this chapter, we review groups of ECs and their sources, occurrence of ECs in groundwater and karst, and current knowledge about the occurrence of ECs in the Edwards Aquifer. We conclude by discussing specific factors, such as rapid flow and contaminant sources, that contribute to the vulnerability of the Edwards Aquifer to contamination by ECs.
Desalination: Growing opportunities in Texas
Authors: Mancha Erika , Walker W. Shane 
Published: October 2019

ABSTRACT
In Texas, the investigation and implementation of desalination began in the 1960s. The earliest operating desalination plants in Texas were in Port Mansfield (south of Corpus Christi) in 1965 and Dell City (far West Texas) in 1968. Since 1999, the number and capacity of desalination plants operating in Texas have steadily increased. In 2016, there were 49 municipal desalination plants in the state, and the total municipal desalination capacity was ~142 million gallons per day (537 million liters per day). The predominant desalination technology used today in municipal desalination plants is reverse osmosis, a membrane filtration process in which dissolved solids (salts) are removed from saline water by applying pressure and forcing the water through a semipermeable membrane. Three desalination plants are currently in operation within the Edwards-Trinity (Plateau) Aquifer boundaries, and additional desalination of brackish groundwater from the Edwards-Trinity (Plateau) and Edwards (Balcones Fault Zone) Aquifers can alleviate stress on water resources from projected population growth and lessen potential water scarcity in central Texas.
Surface geophysics, Edwards and Trinity Aquifers, central Texas
Authors: Saribudak* Mustafa 
Published: October 2019

ABSTRACT
Geophysical methods have been an important component of effective hydrogeologic investigations over the Edwards and Trinity Aquifers in central Texas. Various electrical and electromagnetic methods have been used to map stratigraphy and geologic structure and to locate buried karst features. Geophysical methods can also characterize faults and fractures in the Balcones fault zone. Six case studies across three segments (San Antonio, Barton Springs, and Northern segments) of the Edwards Aquifer show that the locations of buried caves and sinkholes, on all three segments, are best defined using a combination of two- and three-dimensional resistivity imaging and natural potential (self-potential) methods. Localization and characterization of the Haby Crossing and Mount Bonnell faults, which are known to be the most significant faults in the Balcones fault zone, are best accomplished by integrating multiple geophysical methods (e.g., electrical resistivity, natural potential, magnetic, ground-penetrating radar, conductivity, and seismic refraction tomography). It is noted, however, that other karstic regions could respond differently to different geophysical methods and require different primary geophysical methods.
Historical note: The Edwards Aquifer Authority
Authors: Illgner Rick , Schindel Geary M. 
Published: October 2019

ABSTRACT
The Edwards Aquifer Authority (EAA) was established in 1996 after lawsuits that were filed for the protection of endangered species in Comal and San Marcos Springs revealed the need for aquifer management. Several events set the stage for water management in Texas and the creation of the EAA. The EAA succeeded the Edwards Underground Water District, which was formed after the 1951–1956 drought of record. The EAA was eventually granted regulatory responsibilities, including issuing permits for wells, setting limits on groundwater pumpage, and development of a habitat conservation plan to protect endangered species.
Thermophysical properties and mineralogical composition of the Umbria-Marche carbonate succession (central Italy)
Authors: Chicco Jessica , Verdoya Massimo , Giuli Gabriele , Invernizzi Chiara 
Published: October 2019

ABSTRACT
Results from laboratory analyses of thermophysical properties and mineralogical composition of rocks belonging to the main geological formations of the Umbria-Marche stratigraphic succession are presented. We carried out measurements of thermal conductivity, porosity, and density. The samples were mineralogically characterized by means of powder X-ray diffraction and by calcimetry. Scanning electron microscope analyses were conducted to ascertain the absence of mineralized veins, which could have biased the mineralogical composition. A mixing model was also applied to infer the thermal conductivity. The results can be useful to characterize the behavior of shallow geothermal systems in the study region.
Model for development of small carbonate platforms in the Umbria-Marche Apennines supported by strontium isotope stratigraphy
Authors: Lundblad* Steven P. 
Published: October 2019

ABSTRACT
The objective of this research was to determine the age relationships between Early Jurassic sedimentary units in the Umbria-Marche Apennines using strontium isotope stratigraphy. These age relations are critical for evaluating the mechanism by which the small platforms in the region formed. I present an alternative model for carbonate platform differentiation and evolution based on the strontium isotope data; this model relies primarily on growth of individual small platforms through differential sediment accumulation rather than the generally accepted model of extensive late-stage faulting. Strontium isotope stratigraphy provides a high-resolution correlation tool for the region. Because 87Sr/86Sr values steadily decrease in the Hettangian–Pliensbachian section of the Early Jurassic, they illuminate relationships in different carbonate facies very well. This is particularly valuable where physical and/or biostratigraphic correlation is difficult, such as in the Umbria-Marche carbonate platforms.
Strontium isotopic ratios from measured basinal stratigraphic sections along the Burano and Bosso Rivers indicate that at least a 100 m section of the Corniola Formation was deposited while adjacent platforms continued to grow. The small Umbria-Marche platforms drowned synchronously in the late Sinemurian, based on 87Sr/86Sr values from several platforms at the end of Calcare Massiccio Formation deposition. Measured 87Sr/86Sr values for all platforms are the same within error. These stratigraphic relationships indicate that differentiation into shallow- and deep-water facies occurred in the latest Triassic/earliest Jurassic, early in the development of the margin.
Current models explain the differentiation of platforms and basins by late-stage extensive normal faulting, requiring hundreds of meters of stratigraphic throw. Large-displacement faults are not consistent with the age relations determined by strontium isotope stratigraphy in the region. Minor faulting in the Late Triassic coupled with growth by differential sediment accumulation of small, shallow-water carbonate platforms continuing for several million years would produce the exposed platform/basin relationships. Inferred accumulation rates for the platform and basin sequences suggest that the observed relief of the platform escarpments was generated in less than 7 m.y., a time period consistent with the documented stratigraphy in the region.
Terrestrial Cr-spinels in the Maiolica limestone: Where are they from?
Authors: Lenaz Davide , Schmitz Birger , Alvarez Walter 
Published: October 2019

ABSTRACT
In total, 33 and 65 chrome-spinel (Cr-spinel) grains in the &gt;63 and 32–63 μm size fractions, respectively, were recovered from 12 beds in two stratigraphically separated groups along the 240-m-thick Monte Acuto section of the Maiolica limestone in central Italy, spanning from the Berriasian to the early Hauterivian. The chemistry of these detrital spinels suggests they may represent windblown ophiolitic detritus, showing the evolution of an ophiolite evolving from a mid-ocean-ridge basalt setting (Bosso section) to a suprasubduction-zone setting, including a backarc and an arc setting (Monte Acuto section). The source of the Maiolica detrital minerals may have been the obducting ophiolites of the Albanides and/or the Hellenides, which show a similar evolution. In this case, it is particularly important to note how the Cr-spinel detritus in the Maiolica limestone records this evolution over a relatively short period of time, lasting ~10 m.y.
Zircon provenance analysis from Lower Paleocene pelagic limestones of the Bottaccione section at Gubbio (Umbria-Marche basin, Italy)
Authors: Aguirre-Palafox L.E. , Alvarez W. , Boschi S. , Martin E. , Schmitz B. 
Published: October 2019

ABSTRACT
Dating detrital zircon grains from sands and sandstones has become an important geological technique for determining sediment provenance and dispersal patterns. Here, we report what we believe to be the first provenance study of zircon grains extracted by dissolving large samples of pelagic limestone. Our samples come from the Paleocene section of the Umbria-Marche Apennines, Italy. Recovery of these zircon grains was a fortunate by-product of a study on chromite grains aimed to determine the kinds of meteorites that have fallen on Earth through time. The zircons we recovered included both euhedral crystals interpreted as airborne ash from volcanic eruptions of the same age as the sediment in which they were found, and rounded grains interpreted as windblown detrital material with a history of sediment transport, probably derived from desert regions. This study focuses on the rounded grains, to provide constraints on the source region from which they came.
Samples from five levels in the 12 m immediately above the Cretaceous-Paleogene boundary at Gubbio, Italy, yielded detrital zircon grains with ages clustered in eight bands extending back to the Neoarchean. A previous study of this outcrop using proxies for the noncarbonate detrital content had suggested a source region for this dust either in North Africa or in Central Asia. A comparison of our dates from the actual dust grains to geochronological studies from the literature suggests source regions in North Africa and/or the Iberian Peninsula, rather than in Central Asia. In reaching this conclusion, we considered the orogenic events that may have produced each of the eight age bands, the specific source regions that may have supplied zircons from each age group, and the implications for paleoclimate (especially aridity) and paleowind conditions for the few million years just after the Cretaceous-Paleogene boundary.