• 1200 years of Upper Missouri River streamflow reconstructed from tree rings

      Martin, Justin T.; Pederson, Gregory T.; Woodhouse, Connie A.; Cook, Edward R.; McCabe, Gregory J.; Wise, Erika K.; Erger, Patrick; Dolan, Larry; McGuire, Marketa; Gangopadhyay, Subhrendu; et al. (PERGAMON-ELSEVIER SCIENCE LTD, 2019-11-15)
      Paleohydrologic records can provide unique, long-term perspectives on streamflow variability and hydroclimate for use in water resource planning. Such long-term records can also play a key role in placing both present day events and projected future conditions into a broader context than that offered by instrumental observations. However, relative to other major river basins across the western United States, a paucity of streamflow reconstructions has to date prevented the full application of such paleohydrologic information in the Upper Missouri River Basin. Here we utilize a set of naturalized streamflow records for the Upper Missouri and an expanded network of tree-ring records to reconstruct streamflow at thirty-one gaging locations across the major headwaters of the basin. The reconstructions explain an average of 68% of the variability in the observed streamflow records and extend available records of streamflow back to 886 CE on average. Basin-wide analyses suggest unprecedented hydroclimatic variability over the region during the Medieval period, similar to that observed in the Upper Colorado River Basin, and show considerable synchrony of persistent wet-dry phasing with the Colorado River over the last 1200 years. Streamflow estimates in individual sub-basins of the Upper Missouri demonstrate increased spatial variability in discharge during the Little Ice Age (similar to 1400-1850 CE) compared with the Medieval Climate Anomaly (similar to 800-1400 CE). The network of streamflow reconstructions presented here fills a major geographical void in paleohydrologic understanding and now allows for a long-term assessment of hydrological variability over the majority of the western U.S. Published by Elsevier Ltd.
    • Adaptive generalized ZEM-ZEV feedback guidance for planetary landing via a deep reinforcement learning approach

      Furfaro, Roberto; Scorsoglio, Andrea; Linares, Richard; Massari, Mauro; Univ Arizona, Dept Syst & Ind Engn, Dept Aerosp & Mech Engn; Univ Arizona, Dept Syst & Ind Engn (PERGAMON-ELSEVIER SCIENCE LTD, 2020-06)
      Precision landing on large and small planetary bodies is a technology of utmost importance for future human and robotic exploration of the solar system. In this context, the Zero-Effort-Miss/Zero-Effort-Velocity (ZEM/ZEV) feedback guidance algorithm has been studied extensively and is still a field of active research. The algorithm, although powerful in terms of accuracy and ease of implementation, has some limitations. Therefore with this paper we present an adaptive guidance algorithm based on classical ZEM/ZEV in which machine learning is used to overcome its limitations and create a closed loop guidance algorithm that is sufficiently lightweight to be implemented on board spacecraft and flexible enough to be able to adapt to the given constraint scenario. The adopted methodology is an actor-critic reinforcement learning algorithm that learns the parameters of the above-mentioned guidance architecture according to the given problem constraints.
    • Additional comparisons of randomization-test procedures for single-case multiple-baseline designs: Alternative effect types

      Levin, Joel R.; Ferron, John M.; Gafurov, Boris S.; University of Arizona (PERGAMON-ELSEVIER SCIENCE LTD, 2017-08)
      A number of randomization statistical procedures have been developed to analyze the results from single-case multiple-baseline intervention investigations. In a previous simulation study, comparisons of the various procedures revealed distinct differences among them in their ability to detect immediate abrupt intervention effects of moderate size, with some procedures (typically those with randomized intervention start points) exhibiting power that was both respectable and superior to other procedures (typically those with single fixed intervention start points). In Investigation 1 of the present follow-up simulation study, we found that when the same randomization-test procedures were applied to either delayed abrupt or immediate gradual intervention effects: (1) the powers of all of the procedures were severely diminished; and (2) in contrast to the previous study's results, the single fixed intervention start-point procedures generally outperformed those with randomized intervention start points. In Investigation 2 we additionally demonstrated that if researchers are able to successfully anticipate the specific alternative effect types, it is possible for them to formulate adjusted versions of the original randomization-test procedures that can recapture substantial proportions of the lost powers.
    • Agriculture in the process of development: A micro-perspective

      Michler, Jeffrey D.; Univ Arizona, Dept Agr & Resource Econ (PERGAMON-ELSEVIER SCIENCE LTD, 2020-05)
      This paper compares national-level data from India with 40 years of household panel data from rural India to track sectoral changes in employment and income as well as examine the hypothesis of induced innovation in agricultural production. In the national data, India appears to be in the midst of a structural transformation. The share of agriculture in GDP and employment has shrunk while agricultural output continues to grow. This productivity growth appears to adhere to the induced innovation hypothesis, as productivity per hectare has increased more rapidly than productivity per worker. Many of the same patterns exist in the household data. Tracking households across time, I observe agricultural output has increased, despite more households engaging in off-farm labor. Household agricultural production is highly specialized and has increased its reliance on improved inputs. However, while agricultural income has grown, industrial and service income has remained stagnant, and the relative income of these households has declined in recent years. (C) 2020 Elsevier Ltd. All rights reserved.
    • Analytical model for phonon transport analysis of periodic bulk nanoporous structures

      Hao, Qing; Xiao, Yue; Zhao, Hongbo; Department of Aerospace and Mechanical Engineering, University of Arizona (PERGAMON-ELSEVIER SCIENCE LTD, 2017-01-25)
      Phonon transport analysis in nano- and micro-porous materials is critical to their energy-related applications. Assuming diffusive phonon scattering by pore edges, the lattice thermal conductivity can be predicted by modifying the bulk phonon mean free paths with the characteristic length of the nanoporous structure, i.e., the phonon mean free path (Lambda(pore)) for the pore-edge scattering of phonons. In previous studies (Jean et al., 2014), a Monte Carlo (MC) technique have been employed to extract geometry determined Lambda(pore) for nanoporous bulk materials with selected periods and porosities. In other studies (Minnich and Chen, 2007; Machrafi and Lebon, 2015), simple expressions have been proposed to compute Lambda(pore). However, some divergence can often be found between lattice thermal conductivities predicted by phonon MC simulations and by analytical models using Lambda(pore). In this work, the effective Lambda(pore) values are extracted by matching the frequency-dependent phonon MC simulations with the analytical model for nanoporous bulk Si. The obtained Lambda(pore) values are usually smaller than their analytical expressions. These new values are further confirmed by frequency-dependent phonon MC simulations on nano porous bulk Ge. By normalizing the volumetric surface area A and Lambda(pore) with the period length p, the same curve can be used for bulk materials with aligned cubic or spherical pores up to dimensionless p.A of 1.5. Available experimental data for nanoporous Si materials are further analyzed with new Lambda(pore) values. In practice, the proposed model can be employed for the thermal analysis of various nanoporous materials and thus replace the time-consuming phonon MC simulations.
    • Assessing stereophotoclinometry by modeling a physical wall representing asteroid Bennu

      Craft, K.L.; Barnouin, O.S.; Gaskell, R.; Palmer, E.; Weirich, J.; Perry, M.; Bierhaus, B.; Norman, C.; Huish, D.; Olds, R.; et al. (PERGAMON-ELSEVIER SCIENCE LTD, 2020-11)
      The Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission is characterizing the surface and orbital environment of the primitive asteroid (101955) Bennu to enable the collection and return of pristine samples of carbonaceous material. The Altimetry Working Group (AltWG) generates digital terrain models (DTMs) that are essential for assessing the sampleability and science value of potential sample sites. The AltWG uses stereophotoclinometry (SPC) to generate these DTMs from images collected by the OSIRIS-REx Camera Suite. We built and evaluated an SPC-derived DTM by performing a flight-like test, using images (0.4-3 cm per pixel) of a physical test wall constructed to simulate a 3 m x 3m portion of Bennu's surface. We built the DTM using images acquired under similar lighting conditions to those planned for the OSIRIS-REx mission and processed them using flight-like SPC procedures. The results were compared to measurements of the wall obtained using a laser altimeter. We found maximum height differences between the SPC-derived model and the altimetric data of -2.6 and 3.4 cm (or 13-17% of the dynamic range of the heights across the wall), specifically around large surface rocks. For the majority of the SPC-derived model, differences are less than +/- 0.5 cm (<2.5% of the dynamic range of the heights across the wall) or similar to 1.5 x the images' best pixel scale of 0.4 cm. In the spatial frequency domain, spectral correlation and coherency assessments comparing the SPC-derived model and the altimetric data show that the SPC-generated DTMs are an excellent product from wavelengths of similar to 3 m down to shorter wavelengths of similar to 0.1 m. Cross-correlation assessment of images rendered from the SPC-derived model vs. images of the test wall further show that our models accurately reproduce the combined albedo and surface shape, with cross-correlation scores >0.65.
    • ATP-competitive, marine derived natural products that target the DEAD box helicase, eIF4A

      Tillotson, Joseph; Kedzior, Magdalena; Guimarães, Larissa; Ross, Alison B.; Peters, Tara L.; Ambrose, Andrew J.; Schmidlin, Cody J.; Zhang, Donna D.; Costa-Lotufo, Letícia V.; Rodríguez, Abimael D.; et al. (PERGAMON-ELSEVIER SCIENCE LTD, 2017-09-01)
      Activation of translation initiation is a common trait of cancer cells. Formation of the heterotrimeric eukaryotic initiation factor F (eIF4F) complex is the rate-limiting step in 5' m7GpppN cap-dependent translation. This trimeric complex includes the eIF4E cap binding protein, the eIF4G scaffolding protein, and the DEAD box RNA helicase eIF4A. eIF4A is an ATP-dependent helicase and because it is the only enzyme in the eIF4F complex, it has been shown to be a potential therapeutic target for a variety of malignancies. To this end, we have used a simple ATPase biochemical screen to survey several hundred marine and terrestrial derived natural products. Herein, we report the discovery of two natural products from marine sources, elisabatin A (1) and allolaurinterol (2), which show low mu M inhibition of eIF4A ATPase activity. Enzymological analyses revealed 1 and 2 to be ATP-competitive, and cellular evaluations showed reasonable cytotoxicity against A549 (lung cancer) and MDA-MA-468 (breast cancer) cell lines. However, only compound 2 showed potent inhibition of helicase activity congruent with its ATPase inhibitory activity. (C) 2017 Elsevier Ltd. All rights reserved.
    • A benders-local branching algorithm for second-generation biodiesel supply chain network design under epistemic uncertainty

      Babazadeh, Reza; Ghaderi, Hamid; Pishvaee, Mir Saman; Univ Arizona, Dept Syst & Ind Engn (PERGAMON-ELSEVIER SCIENCE LTD, 2019-05-08)
      This paper proposes a possibilistic programming model in order to design a second-generation biodiesel supply chain network under epistemic uncertainty of input data. The developed model minimizes the total cost of the supply chain from supply centers to the biodiesel and glycerin consumer centers. Waste cooking oil and Jatropha plants, as non-edible feedstocks, are considered for biodiesel production. To cope with the epistemic uncertainty of the parameters, a credibility-based possibilistic programming approach is employed to convert the original possibilistic programming model into a crisp counterpart. An accelerated benders decomposition algorithm using efficient acceleration mechanisms is devised to deal with the computational complexity of solving the proposed model in an efficient manner. The performance of the proposed possibilistic programming model and the efficiency of the developed accelerated benders decomposition algorithm are validated by performing a computational analysis using a real case study in Iran. (C) 2019 Elsevier Ltd. All rights reserved.
    • Biogeographic patterns of microbial co-occurrence ecological networks in six American forests

      Tu, Qichao; Yan, Qingyun; Deng, Ye; Michaletz, Sean T.; Buzzard, Vanessa; Weiser, Michael D.; Waide, Robert; Ning, Daliang; Wu, Liyou; He, Zhili; et al. (PERGAMON-ELSEVIER SCIENCE LTD, 2020-09)
      Rather than simple accumulation of individual populations, microorganisms in natural ecosystems form complex ecological networks that are critical to maintain ecosystem functions and services. Although various studies have examined the patterns of microbial community diversity and composition across spatial gradients, whether microbial co-occurrence relationships follow similar patterns remains an open question. In this study, we determined the biogeographic patterns of microbial co-occurrence networks of bacteria, fungi and nitrogen (N) fixer via analyses of high throughput amplicon sequencing data of 16S rRNA, ITS, and nifH genes from 126 forest soil samples across six forests in America. Microbial co-occurrence networks were constructed using a Random Matrix Theory based approach. Network parameters were calculated and correlated with biogeographic parameters. Gradient patterns along with biogeographic parameters were observed for network topologies. Significantly different network topologies were observed between microbial co-occurrence networks in tropical and temperate forest ecosystems. Among various biogeographic parameters potentially related with network topology indices, temperature seemed to be the strongest one. These results suggest that biogeographic variables like temperature not only mediate microbial community diversity and composition, but also the co-occurrence ecological networks among microbial species.
    • Blast Exposure Disrupts the Tonotopic Frequency Map in the Primary Auditory Cortex

      Masri, Samer; Zhang, Li S.; Luo, Hao; Pace, Edward; Zhang, Jinsheng; Bao, Shaowen; Univ Arizona, Neurosci Grad Program; Univ Arizona, Dept Physiol (PERGAMON-ELSEVIER SCIENCE LTD, 2018-05-21)
      Blast exposure can cause various auditory disorders including tinnitus, hyperacusis, and other central auditory processing disorders. While this is suggestive of pathologies in the central auditory system, the impact of blast exposure on central auditory processing remains poorly understood. Here we examined the effects of blast shockwaves on acoustic response properties and the tonotopic frequency map in the auditory cortex. We found that multiunits recorded from the auditory cortex exhibited higher acoustic thresholds and broader frequency tuning in blast-exposed animals. Furthermore, the frequency map in the primary auditory cortex was distorted. These changes may contribute to central auditory processing disorders. (C) 2018 IBRO. Published by Elsevier Ltd. All rights reserved.
    • Cooling rates of LL, L and H chondrites and constraints on the duration of peak thermal conditions: Diffusion kinetic modeling and implications for fragmentation of asteroids and impact resetting of petrologic types

      Ganguly, Jibamitra; Tirone, Massimiliano; Domanik, Kenneth; Univ Arizona, Dept Geosci; Univ Arizona, Lunar & Planetary Lab (PERGAMON-ELSEVIER SCIENCE LTD, 2016-11)
      We have carried out detailed thermometric and cooling history studies of several LL-, L- and H-chondrites of petrologic types 5 and 6. Among the selected samples, the low-temperature cooling of St. Severin (LL6) has been constrained in an earlier study by thermochronological data to an average rate of similar to 2.6 degrees C/My below 500 degrees C. However, numerical simulations of the development of Fe-Mg profiles in Opx-Cpx pairs using this cooling rate grossly misfit the measured compositional profiles. Satisfactory simulation of the latter and low temperature thermochronological constraints requires a two-stage cooling model with a cooling rate of similar to 50-200 degrees C/ky from the peak metamorphic temperature of similar to 875 degrees C down to 450 degrees C, and then transitioning to very slow cooling with an average rate of similar to 2.6 degrees C/My. Similar rapid high temperature cooling rates (200-600 degrees C/ky) are also required to successfully model the compositional profiles in the Opx-Cpx pairs in the other samples of L5, L6 chondrites. For the H-chondrite samples, the low temperature cooling rates were determined earlier to be 10-20 degrees C/My by metallographic method. As in St. Severin, these cooling rates grossly misfit the compositional profiles in the Opx-Cpx pairs. Modeling of these profiles requires very rapid cooling, similar to 200-400 degrees C/ky, from the peak temperatures (similar to 810-830 degrees C), transitioning to the metallographic rates at similar to 450-500 degrees C. We interpret the rapid high temperature cooling rates to the exposure of the samples to surface or near surface conditions as a result of fragmentation of the parent body by asteroidal impacts. Using the thermochronological data, the timing of the presumed impact is constrained to be similar to 4555-4560 My before present for St. Severin. We also deduced similar two stage cooling models in earlier studies of H-chondrites and mesosiderites that could be explained, using the available geochronological data, by impact induced fragmentation at around the same time. Diffusion kinetic analysis shows that if a lower petrological type got transformed by the thermal effect of shock impacts to reflect higher metamorphic temperature, as has been suggested as a possibility, then the peak temperatures would have had to be sustained for at least 10 ky and 80 ky, respectively, for transformation to the petrologic types 6 and 4. Finally, we present a model that reconciles textural data supporting an onion-shell parent body of H-chondrites with rapid cooling rate at high temperature caused by impact induced disturbance, and also discuss alternatives to the onion shell parent body model. (C) 2016 Elsevier Ltd. All rights reserved.
    • A critical analysis of recreational water guidelines developed from temperate climate data and applied to the tropics

      Verhougstraete, Marc P; Pogreba-Brown, Kristen; Reynolds, Kelly A; Lamparelli, Claudia Condé; Zanoli Sato, Maria Inês; Wade, Timothy J; Eisenberg, Joseph N S; Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth, Dept Community Environm & Policy; Univ Arizona, Mel & Enid Zuckerman Coll Publ Hlth, Dept Epidemiol & Biostat (PERGAMON-ELSEVIER SCIENCE LTD, 2020-03-01)
      Recreational water epidemiology studies are rare in settings with minimal wastewater treatment where risk may be highest, and in tropical settings where warmer temperature influences the ecology of fecal indicator bacteria commonly used to monitor recreational waters. One exception is a 1999 study conducted in Sao Paulo Brazil. We compared the risk and exposure characteristics of these data with those conducted in the United Kingdom (UK) in the early 1990s that are the basis of the World Health Organization's (WHO) guidelines on recreational water risks. We then developed adjusted risk difference models (excess gastrointestinal illness per swimming event) for children (<10 years of age) and nonchildren (>= 10 years of age) across five Brazil beaches. We used these models along with beach water quality data from 2004 to 2015 to assess spatial and temporal trends in water quality and human risk. Risk models indicate that children in Brazil have as much as two times the risk of gastrointestinal illness than non-children. In Brazil, 11.8% of the weekly water samples from 2004 to 2015 exceeded 158 enterococci CFU/100 ml, the highest level of fecal streptococci concentration measured in the UK study. Risks associated with these elevated levels equated to median NEEAR-Gastrointestinal Illness (NGI) risks of 53 and 96 excess cases per 1000 swimmers in non-children and children, respectively. Two of the five beaches appear to drive the overall elevated NGI risks seen during this study. Distinct enteric pathogen profiles that exist in tropical settings as well as in settings with minimal wastewater treatment highlight the importance of regionally specific guideline development. (C) 2019 Elsevier Ltd. All rights reserved.
    • Crustal structure of north Peru from analysis of teleseismic receiver functions

      Condori, Cristobal; França, George S.; Tavera, Hernando J.; Albuquerque, Diogo F.; Bishop, Brandon T.; Beck, Susan L.; University of Arizona UA, Department of Geosciences (PERGAMON-ELSEVIER SCIENCE LTD, 2017-07)
      In this study, we present results from teleseismic receiver functions, in order to investigate the crustal thickness and Vp/Vs ratio beneath northern Peru. A total number of 981 receiver functions were analyzed, from data recorded by 28 broadband seismic stations from the Peruvian permanent seismic network, the regional temporary SisNort network and one CTBTO station. The Moho depth and average crustal Vp/Vs ratio were determined at each station using the H-k stacking technique to identify the arrival times of primary P to S conversion and crustal reverberations (PpPms, PpSs + PsPms). The results show that the Moho depth correlates well with the surface topography and varies significantly from west to east, showing a shallow depth of around 25 km near the coast, a maximum depth of 55-60 km beneath the Andean Cordillera, and a depth of 35-40 km further to the east in the Amazonian Basin. The bulk crustal Vp/Vs ratio ranges between 1.60 and 1.88 with the mean of 1.75. Higher values between 1.75 and 1.88 are found beneath the Eastern and Western Cordilleras, consistent with a mafic composition in the lower crust. In contrast values vary from 1.60 to 1.75 in the extreme flanks of the Eastern and Western Cordillera indicating a felsic composition. We find a positive relationship between crustal thickness, Vp/ Vs ratio, the Bouguer anomaly, and topography. These results are consistent with previous studies in other parts of Peru (central and southern regions) and provide the first crustal thickness estimates for the high cordillera in northern Peru.
    • Cyclic biphalin analogues with a novel linker lead to potent agonist activities at mu, delta, and kappa opioid receptors

      Remesic, Michael; Macedonio, Giorgia; Mollica, Adriano; Porreca, Frank; Hruby, Victor; Lee, Yeon Sun; Univ Arizona, Dept Chem & Biochem; Univ Arizona, Dept Pharmacol (PERGAMON-ELSEVIER SCIENCE LTD, 2018-07-23)
      In an effort to improve biphalin's potency and efficacy at the mu-( MOR) and delta-opioid receptors (DOR), a series of cyclic biphalin analogues 1-5 with a cystamine or piperazine linker at the C-terminus were designed and synthesized by solution phase synthesis using Boc-chemistry. Interestingly, all of the analogues showed balanced opioid agonist activities at all opioid receptor subtypes due to enhanced.-opioid receptor (KOR) activity. Our results indicate that C-terminal flexible linkers play an important role in KOR activity compared to that of the other cyclic biphalin analogues with a hydrazine linker. Among them, analogue 5 is a potent (Ki= 0.27, 0.46, and 0.87 nM; EC50= 3.47, 1.45, and 13.5 nM at MOR, DOR, and KOR, respectively) opioid agonist with high efficacy. Based on the high potency and efficacy at the three opioid receptor subtypes, the ligand is expected to have a potential synergistic effect on relieving pain and further studies including in vivo tests are worthwhile.
    • Degradation of Ir-Ta oxide coated Ti anodes in sulfuric acid solutions containing fluoride

      Ma, Dongni; Ngo, Vanda; Raghavan, Srini; Sandoval, Scot; Univ Arizona, Dept Chem & Environm Engn; Univ Arizona, Dept Mat Sci & Engn (PERGAMON-ELSEVIER SCIENCE LTD, 2020-03)
      The lifetime of IrO2-Ta2O5 coated titanium anodes has been investigated using a galvanostatic accelerated life test (ALT) method in 2 M (2000 mol/m(3)) H2SO4 solutions containing fluoride. Fluoride addition in the concentration range of 25 - 200 ppm significantly reduces the lifetime of films through localized thinning and in some cases, complete removal of film. While the presence of fluoride does not affect the overpotential for oxygen evolution, it lowers the efficacy of oxygen evolution. Complexation of fluoride by aluminum ions reduces the deleterious effects of fluoride. Based on thermodynamic and XPS analyses, a degradation mechanism has been proposed.
    • Dietary flavonoids improve urinary arsenic elimination among Mexican women

      Quiller, Grant; Mérida-Ortega, Ángel; Rothenberg, Stephen J; Cebrián, Mariano E; Gandolfi, A Jay; Franco-Marina, Francisco; López-Carrillo, Lizbeth; Univ Arizona, Coll Pharm, Dept Pharmacol & Toxicol (PERGAMON-ELSEVIER SCIENCE LTD, 2018-07)
      Inorganic arsenic (iAs) exposure increases risk of several diseases, including cancer. Some nutrients such as flavonoids enhance glutathione activity, which in turn play a key role in iAs elimination. Our objective was to explore whether dietary non-soy flavonoids are associated with iAs metabolism. We hypothesized that the intake of flavonoids belonging to the following groups, flavan-3-ols, flavone, flavonol, flavanone, and anthocyanidin, is positively associated with urinary dimethylarsinic acid (DMA), which is the most soluble iAs metabolite excreted. We performed a cross-sectional study that included 1027 women living in an arsenic-contaminated area of northern Mexico. Flavonoid intake was estimated using a validated food frequency questionnaire. Concentration of urinary iAs and its metabolites (monomethylarsonic acid and DMA) were determined by high performance liquid chromatography ICP-MS. Results showed positive significant associations between DMA and the flavonoid groups flava-3-ols (beta= 0.0112) and flavones (beta= 0.0144), as well as the individual intake of apigenin (beta= 0.0115), luteolin (beta= 0.0138), and eriodictyol (beta= 0.0026). Our findings suggest that certain non-soy flavonoids may improve iAs elimination; however, there is still very limited information available regarding the consumption of flavonoids and iAs metabolism. (C) 2018 Elsevier Inc. All rights reserved.
    • Dynamic pore-network modeling of air-water flow through thin porous layers

      Qin, Chao-Zhong; Guo, Bo; Celia, Michael; Wu, Rui; Univ Arizona, Dept Hydrol & Atmospher Sci (PERGAMON-ELSEVIER SCIENCE LTD, 2019-07-20)
      Thin porous layers, that have large aspect ratios, are seen in many applications such as hydrogen fuel cells and hygiene products, in which air-water immiscible flow is of great interest. Direct numerical simulations based on Navier-Stokes equation are computationally expensive, and even prohibitive for low capillary number flow such as water flooding in low-temperature polymer electrolyte fuel cells. Alternatively, the pore-network modeling needs much less computational resources, while still retaining essentials of the pore-structure information. In this work, a dynamic pore-network model of air-water flow with phase change has been developed. We focus on drainage processes through thin porous layers, in which liquid water is the nonwetting phase. Three test cases are conducted, namely, air-water flow through a thin porous layer, air-water flow through a bilayer of fine and coarse thin porous layers, and water flooding in the gas diffusion layer of a polymer electrolyte fuel cell with phase change between water and its vapor. Using these test cases, we aim to demonstrate the application of dynamic pore-network modeling in thin porous media studies. In particular, we discuss the challenge of modeling thin porous media at the average scale, and highlight the role of phase change in removing liquid water from the cathode gas diffusion layer. (C) 2019 Elsevier Ltd. All rights reserved.
    • Effect of brief exercise on urges to smoke in men and women smokers

      Allen, Alicia M.; Abdelwahab, Nermine M.; Carlson, Samantha; Bosch, Tyler A.; Eberly, Lynn E.; Okuyemi, Kola; Univ Arizona, Coll Med, Dept Family & Community Med (PERGAMON-ELSEVIER SCIENCE LTD, 2018-02)
      Introduction: Although smoking urges have been demonstrated to vary by gender and also be influenced by exercise, it is unknown if exercise has a differential effect on smoking urges by gender. This study aimed to explore gender-specific effects of an acute bout of exercise on cessation-related symptoms in men and women smokers during acute abstinence. Methods: We enrolled smokers (5 cigarettes/day) who were 18-40 years old for a study on exercise and smoking behavior. Participants abstained from smoking for at least 3 h, prior to measurement of their maximal oxygen consumption tested, which was the acute bout of exercise. Prior to and after the exercise, participants completed the Questionnaire of Smoking Urges Brief and the Minnesota Nicotine Withdrawal Scale. Results: Participants (n = 38; 61% women) were, on average, 30.0 0.9 years old and smoked 13.0 0.8 cigarettes/day. All measured aspects of cessation-related symptoms significantly improved after the exercise in both men and women. In women there was a significant decline in anticipated relief from negative affect after the exercise (women: 0.45 0.20, p = 0.0322; men: 0.41 0.26, p = 0.1312). In men there was a significant decline in the intention to smoke after the exercise (men: 0.77 0.23, p = 0.0053; women: 0.66 0.37, p = 0.0909). Conclusions: An acute bout of exercise reduced smoking urges in both men and women smokers during an acute state of abstinence. Additional research is needed to replicate these observations in a larger, more diverse sample, and to explore the implication of these observations on cessation.
    • Effect of exogenous progesterone administration on cigarette smoking-related symptomology in oral contraceptive users who smoke

      Harrison, Katherine; Petersen, Ashley; Tosun, Nicole; Crist, Katherine; Allen, Alicia M; Allene, Sharon; Univ Arizona, Dept Family & Community Med (PERGAMON-ELSEVIER SCIENCE LTD, 2020-03)
      Cigarette smoking-related symptomatology (e.g., craving; SRS) is linked to relapse after a quit attempt. SRS varies by menstrual phase, possibly due to variations in sex hormones (e.g., progesterone), though much of the research to-date has relied on observations from the menstrual cycle acting as a proxy for hormone levels. The goal of this study was to examine the effect of exogenous progesterone on SRS during ad libitum smoking and following overnight abstinence. Oral contraceptive users who smoked completed two 9-day crossover testing periods (7 days of ad libitum smoking and 2 days following overnight abstinence) while taking double-blind active/placebo exogenous progesterone. Participants completed questionnaires to measure SRS. The effect of exogenous progesterone and endogenous hormones (progesterone, estradiol, and progesterone-to-estradiol [P/E2] ratio) on SRS was assessed with paired t-tests and linear mixed effect models. Participants (n = 53) were, on average, 24 years old and smoked 11 cigarettes per day. During ad libitum smoking, a doubling of the P/E2 ratio was associated with 0.09 points lower anticipated relief from negative affect (95% confidence interval [CI]: 0.03-0.15 points lower; p = 0.008) and 0.11 points lower psychological reward (95% CI: 0.03-0.18 points lower; p = 0.006). After correction for multiple testing, these associations were not statistically significant: anticipated relief from negative effect (p = 0.10) and psychological reward (p = 0.09). No other significant associations were observed. Although substantial previous literature indicates that progesterone influences SRS, exogenous progesterone administration did not alter SRS here. Additional research is needed to elucidate alternative mechanisms involved in menstrual phase effects on SRS.
    • Effect of nonalcoholic steatohepatitis on renal filtration and secretion of adefovir.

      Laho, Tomas; Clarke, John D; Dzierlenga, Anika L; Li, Hui; Klein, David M; Goedken, Michael; Micuda, Stanislav; Cherrington, Nathan J; Univ Arizona, Dept Pharmacol & Toxicol (PERGAMON-ELSEVIER SCIENCE LTD, 2016-09-01)
      Adefovir, an acyclic nucleotide reverse transcriptase inhibitor used to treat hepatitis B viral infection, is primarily eliminated renally through cooperation of glomerular filtration with active tubular transport. Nonalcoholic steatohepatitis is a variable in drug disposition, yet the impact on renal transport processes has yet to be fully understood. The goal of this study was to determine the effect of nonalcoholic steatohepatitis on the pharmacokinetics of adefovir in rats given a control or methionine and choline deficient diet to induce nonalcoholic steatohepatitis.