Fingerprints of changes in the terrestrial carbon cycle in response to large reorganizations in ocean circulation

CO2 and carbon cycle changes in the land, ocean and atmosphere are investigated using the comprehensive carbon cycle-climate model NCAR CSM1.4-carbon. Ensemble simulations are forced with freshwater perturbations applied at the North Atlantic and Southern Ocean deep water formation sites under pre-industrial climate conditions. As a result, the Atlantic Meridional Overturning Circulation reduces in each experiment to varying degrees. The physical climate fields show changes qualitatively in agreement with results documented in the literature, but there is a clear distinction between northern and southern perturbations. Changes in the physical variables, in turn, affect the land and ocean biogeochemical cycles and cause a reduction, or an increase, in the atmospheric CO2 concentration by up to 20 ppmv, depending on the location of the perturbation. In the case of a North Atlantic perturbation, the land biosphere reacts with a strong reduction in carbon stocks in some tropical locations and in high northern latitudes. In contrast, land carbon stocks tend to increase in response to a southern perturbation. The ocean is generally a sink of carbon although large reorganizations occur throughout various basins. The response of the land biosphere is strongest in the tropical regions due to a shift of the Intertropical Convergence Zone. The carbon fingerprints of this shift, either to the south or to the north depending on where the freshwater is applied, can be found most clearly in South America. For this reason, a compilation of various paleoclimate proxy records of Younger Dryas precipitation changes are compared with our model results. The proxy records, in general, show good agreement with the model's response to a North Atlantic freshwater perturbation.

Role of Acetylcholine in Control of Sexual Behavior of Male and Female Mammals

The results of studies using systemic or central applications of cholinergic drugs suggest that acetylcholine makes important contributions to the neurochemical control of male- and female-typical reproductive behaviors. In males, cholinergic control seems largely specific to some elements or aspects of copulatory behavior that can vary significantly across species. Synapses in or near the medial preoptic area represent part of this mechanism, but the entire system appears to extend more widely, perhaps especially to one or more structures flanking some part of the lateral ventricle. In females, the lordosis response that essentially defines sexual receptivity is clearly responsive to cholinergic drugs. The same seems likely to be true of other elements of female sexual behavior, but additional studies will be needed to confirm this. Changes in cholinergic activity may help to mediate estrogenic effects on female sexual behavior. However, estrogen exposure can increase or decrease cholinergic effects, suggesting a relationship that is complex and requires further analysis. Also presently unclear is the localization of the cholinergic effects on female sexual responses. Though periventricular sites again have been implicated, their identity is presently unknown. This review discusses these and other aspects of the central cholinergic systems affecting male and female sexual behaviors. Copyright 2014 Elsevier Inc. All rights reserved.

Paleoenvironment and Paleoecology of a Late Paleocene High-Latitude Terrestrial Succession, Arkose Ridge Formation at Box Canyon, Southern Talkeetna Mountains, Alaska

Paleogene sedimentary rocks of the Arkose Ridge Formation (Talkeetna Mountains, Alaska) preserve a record of a fluvial-lacustrine depositional environment and its forested ecosystem in an active basin among the convergent margin tectonic processes that shaped southern Alaska. An -800 m measured succession at Box Canyon indicates braid-plain deposition with predominantly gravelly deposits low in the exposure to sandy and muddy facies associations below an overlying lava flow sequence. U-Pb geochronology on zircons from a tuff and a sandstone within the measured section, as well as an Ar/Ar date from the overlying lava constrain the age of the sedimentary succession to between similar to 59 Ma and 48 Ma Fossil plant remains occur throughout the Arkose Ridge Formation as poorly-preserved coalified woody debris and fragmentary leaf impressions. At Box Canyon, however, a thin la-custrine depositional lens of rhythmically laminated mudrocks yielded fish fossils and a well-preserved floral assemblage including foliage and reproductive organs representing conifers, sphenopsids, monocots, and dicots. Leaf physiognomic methods to estimate paleoclimate were applied to the dicot leaf collection and indicate warm temperate paleotemperatures (-11-15 +/- -4 degrees C MAT) and elevated paleoprecipitation (-120 cm/yr MAP) estimates as compared to modem conditions; results that are parallel with previously published estimates from the partly coeval Chickaloon Formation deposited in more distal depositional environments in the same basin. The low abundance of leaf herbivory in the Box Canyon dicot assemblage (-9% of leaves damaged) is also similar to the results from assemblages in the meander-plain depositional systems of the Chickaloon. This new suite of data informs models of the tectonostratigraphic evolution of southern Alaska and the developing understanding of terrestrial paleoecology and paleoclimate at high latitudes during the Late Paleocene-Early Eocene greenhouse climate phase. (c) 2014 Elsevier B.V. All rights reserved.

Perinatal adaptation in mammals: the impact of metabolic rate

Mammalian birth is accompanied by profound changes in metabolic rate that can be described in terms of body size relationship (Kleiber's rule). Whereas the fetus, probably as an adaptation to the low intrauterine pO2, exhibits an "inappropriately" low, adult-like specific metabolic rate, the term neonate undergoes a rapid metabolic increase up to the level to be expected from body size. A similar, albeit slowed, "switching-on" of metabolic size allometry is found in human preterm neonates whereas animals that are normally born in a very immature state are able to retard or even suppress the postnatal metabolic increase in favor of weight gain and O2 supply. Moreover, small immature mammalian neonates exhibit a temporary oxyconforming behavior which enhances their hypoxia tolerance, yet is lost to the extent by which the size-adjusted metabolic rate is "locked" by increasing mitochondrial density. Beyond the perinatal period, there are no other deviations from metabolic size allometry among mammals except in hibernation where the temporary "switching-off" of Kleiber's rule is accompanied by a deep reduction in tissue pO2. This gives support to the hypothesis that the postnatal metabolic increase represents an "escape from oxygen" similar to the evolutionary roots of mitochondrial respiration, and that the overall increase in specific metabolic rate with decreasing size might contribute to prevent tissues from O2 toxicity.

Development of one-dimensional and two-dimensional computational tools that simulate steady internal condensing flows in terrestrial and zero-gravity environments

This dissertation presents an effective quasi one-dimensional (1-D) computational simulation tool and a full two-dimensional (2-D) computational simulation methodology for steady annular/stratified internal condensing flows of pure vapor. These simulation tools are used to investigate internal condensing flows in both gravity as well as shear driven environments. Through accurate numerical simulations of the full two dimensional governing equations, results for laminar/laminar condensing flows inside mm-scale ducts are presented. The methodology has been developed using MATLAB/COMSOL platform and is currently capable of simulating film-wise condensation for steady (and unsteady flows). Moreover, a novel 1-D solution technique, capable of simulating condensing flows inside rectangular and circular ducts with different thermal boundary conditions is also presented. The results obtained from the 2-D scientific tool and 1-D engineering tool, are validated and synthesized with experimental results for gravity dominated flows inside vertical tube and inclined channel; and, also, for shear/pressure driven flows inside horizontal channels. Furthermore, these simulation tools are employed to demonstrate key differences of physics between gravity dominated and shear/pressure driven flows. A transition map that distinguishes shear driven, gravity driven, and “mixed” driven flow zones within the non-dimensional parameter space that govern these duct flows is presented along with the film thickness and heat transfer correlations that are valid in these zones. It has also been shown that internal condensing flows in a micro-meter scale duct experiences shear driven flow, even in different gravitational environments. The full 2-D steady computational tool has been employed to investigate the length of annularity. The result for a shear driven flow in a horizontal channel shows that in absence of any noise or pressure fluctuation at the inlet, the onset of non-annularity is partly due to insufficient shear at the liquid-vapor interface. This result is being further corroborated/investigated by R. R. Naik with the help of the unsteady simulation tool. The condensing flow results and flow physics understanding developed through these simulation tools will be instrumental in reliable design of modern micro-scale and spacebased thermal systems.

Evaluation of surface defect detection in reinforced concrete bridge decks using terrestrial LiDAR

Routine bridge inspections require labor intensive and highly subjective visual interpretation to determine bridge deck surface condition. Light Detection and Ranging (LiDAR) a relatively new class of survey instrument has become a popular and increasingly used technology for providing as-built and inventory data in civil applications. While an increasing number of private and governmental agencies possess terrestrial and mobile LiDAR systems, an understanding of the technology’s capabilities and potential applications continues to evolve. LiDAR is a line-of-sight instrument and as such, care must be taken when establishing scan locations and resolution to allow the capture of data at an adequate resolution for defining features that contribute to the analysis of bridge deck surface condition. Information such as the location, area, and volume of spalling on deck surfaces, undersides, and support columns can be derived from properly collected LiDAR point clouds. The LiDAR point clouds contain information that can provide quantitative surface condition information, resulting in more accurate structural health monitoring. LiDAR scans were collected at three study bridges, each of which displayed a varying degree of degradation. A variety of commercially available analysis tools and an independently developed algorithm written in ArcGIS Python (ArcPy) were used to locate and quantify surface defects such as location, volume, and area of spalls. The results were visual and numerically displayed in a user-friendly web-based decision support tool integrating prior bridge condition metrics for comparison. LiDAR data processing procedures along with strengths and limitations of point clouds for defining features useful for assessing bridge deck condition are discussed. Point cloud density and incidence angle are two attributes that must be managed carefully to ensure data collected are of high quality and useful for bridge condition evaluation. When collected properly to ensure effective evaluation of bridge surface condition, LiDAR data can be analyzed to provide a useful data set from which to derive bridge deck condition information.