bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multilocus phylogeography of the European ground squirrel: cryptic interglacial refugia of continental climate in Europe
Authors: Říčanová Štěpánka , Koshev Yordan , Říčan Oldřich , Ćosić Nada , Ćirović Duško , Sedláček František , Bryja Josef 
Published: July 2013

AbstractThe theory of classical and cryptic Pleistocene refugia is based mainly on historical changes in temperature, and the refugia are usually defined within a latitudinal gradient. However, the gradient of oceanic–continental climate (i.e. longitudinal) was also significantly variable during glacial cycles with important biotic consequences. Range‐wide phylogeography of the European ground squirrel (EGS) was used to interpret the evolutionary and palaeogeographical history of the species in Europe and to shed light on its glacial–interglacial dynamic. The EGS is a steppe‐inhabiting species and the westernmost member of the genus in the Palaearctic region. We have analysed 915 specimens throughout the present natural range by employing mitochondrial DNA sequences (cytochrome b gene) and 12 nuclear microsatellite markers. The reconstructed phylogeography divides the species into two main geographical groups, with deep substructuring within both groups. Bulgaria is the centre of the ancestral area, and it also has the highest genetic diversity within the species. The northernmost group of the EGS survived in the southern part of Pannonia throughout several glacial–interglacial cycles. Animals from this population probably repeatedly colonized areas further to the north and west during the glacial periods, while in the interglacial periods, the EGS distribution contracted back to this Pannonian refugium. The EGS thus represents a species with a glacial expansion/interglacial contraction palaeogeographical dynamics, and the Pannonian and southeastern Balkanian steppes are supported as cryptic refugia of continental climate during Pleistocene interglacials.
Contrasting genetic responses to population fragmentation in a coevolving fig and fig wasp across a mainland–island archipelago
Authors: Liu Min , Zhang Jian , Chen Yan , Compton Stephen G. , Chen Xiao‐Yong 
Published: July 2013

AbstractInteracting species of pollinator–host systems, especially the obligate ones, are sensitive to habitat fragmentation, due to the nature of mutual dependence. Comparative studies of genetic structure can provide insights into how habitat fragmentation contributes to patterns of genetic divergence among populations of the interacting species. In this study, we used microsatellites to analyse genetic variation in Chinese populations of a typical mutualistic system – Ficus pumila and its obligate pollinator Wiebesia sp. 1 – in a naturally fragmented landscape. The plants and wasps showed discordant patterns of genetic variation and geographical divergence. There was no significant positive relationship in genetic diversity between the two species. Significant isolation‐by‐distance (IBD) patterns occurred across the populations of F. pumila and Wiebesia sp. 1 as whole, and IBD also occurred among island populations of the wasps, but not the plants. However, there was no significant positive relationship in genetic differentiation between them. The pollinator populations had significantly lower genetic variation in small habitat patches than in larger patches, and three island pollinator populations showed evidence of a recent bottleneck event. No effects of patch size or genetic bottlenecks were evident in the plant populations. Collectively, the results indicate that, in more fragmented habitats, the pollinators, but not the plants, have experienced reduced genetic variation. The contrasting patterns have multiple potential causes, including differences in longevity and hence number of generations experiencing fragmentation; different dispersal patterns, with the host's genes dispersed as seeds as well as a result of pollen dispersal via the pollinator; asymmetrical responses to fluctuations in partner populations; and co‐existence of a rare second pollinating wasp on some islands. These results indicate that strongly interdependent species may respond in markedly different ways to habitat fragmentation.
The role of hybridization in the origin and spread of asexuality in Daphnia
Authors: Xu Sen , Innes David J. , Lynch Michael , Cristescu Melania E. 
Published: July 2013

AbstractThe molecular mechanisms leading to asexuality remain little understood despite their substantial bearing on why sexual reproduction is dominant in nature. Here, we examine the role of hybridization in the origin and spread of obligate asexuality in Daphnia pulex, arguably the best‐documented case of contagious asexuality. Obligately parthenogenetic (OP) clones of D. pulex have traditionally been separated into ‘hybrid’ (Ldh SF) and ‘nonhybrid’ (Ldh SS) forms because the lactase dehydrogenase (Ldh) locus distinguishes the cyclically parthenogenetic (CP) lake dwelling Daphnia pulicaria (Ldh FF) from its ephemeral pond dwelling sister species D. pulex (Ldh SS). The results of our population genetic analyses based on microsatellite loci suggest that both Ldh SS and SF OP individuals can originate from the crossing of CP female F1 (D. pulex × D. pulicaria) and backcross with males from OP lineages carrying genes that suppress meiosis specifically in female offspring. In previous studies, a suite of diagnostic markers was found to be associated with OP in Ldh SS D. pulex lineages. Our association mapping supports a similar genetic mechanism for the spread of obligate parthenogenesis in Ldh SF OP individuals. Interestingly, our study shows that CP D. pulicaria carry many of the diagnostic microsatellite alleles associated with obligate parthenogenesis. We argue that the assemblage of mutations that suppress meiosis and underlie obligate parthenogenesis in D. pulex originated due to a unique historical hybridization and introgression event between D. pulex and D. pulicaria.
Regulation of the KstR2 regulon of Mycobacterium tuberculosis by a cholesterol catabolite
Authors: Casabon Israël , Zhu Song‐Hua , Otani Hiroshi , Liu Jie , Mohn William W. , Eltis Lindsay D. 
Published: July 2013

SummaryCholesterol catabolism is widespread in actinobacteria and is critical for Mycobacterium tuberculosis (Mtb) virulence. Catabolism of steroid nucleus rings C and D is poorly understood: it is initiated by the CoA thioesterification of 3aα‐H‐4α(3′‐propanoate)‐7aβ‐methylhexahydro‐1,5‐indanedione (HIP) by FadD3, whose gene is part of the KstR2 regulon. In Mtb, genes of this regulon were upregulated up to 30‐ and 22‐fold during growth on cholesterol and HIP, respectively, versus another minimal medium. In contrast, genes involved in degrading the cholesterol side‐chain and nucleus rings A and B were only upregulated during growth on cholesterol. Similar results were obtained in Rhodococcus jostii RHA1. Moreover, the regulon was not upregulated in a ΔfadD3 mutant unable to produce HIP‐CoA. In electrophoretic mobility shift assays, HIP‐CoA relieved the binding of KstR2Mtb to each of three KstR2 boxes: CoASH, HIP and a related CoA thioester did not. Inspection of the structure of KstR2RHA1 revealed no obvious HIP‐CoA binding pocket. The results establish that Mtb can catabolize the entire cholesterol molecule and that HIP‐CoA is an effector of KstR2. They further indicate that KstR2 specifically represses the expression of the HIP degradation genes in actinobacteria, which encode a lower pathway involved in the catabolism of multiple steroids.
Modest efficacy of voriconazole against murine infections by Sporothrix schenckii and lack of efficacy against Sporothrix brasiliensis
Authors: Fernández‐Silva Fabiola , Capilla Javier , Mayayo Emilio , Guarro Josep 
Published: July 2013

SummaryThe efficacy of voriconazole (VRC) was evaluated against two strains of each of the two most common species causing sporotrichosis, Sporothrix schenckii sensu stricto and Sporothrix brasiliensis, using a murine model of disseminated infection. Voriconazole was administered at doses of 20 or 40 mg kg−1 per day by gavage. The drug showed some efficacy, especially at 40 mg kg−1 per day, in prolonging the survival and reducing fungal load in spleen and liver in mice infected with S. schenckii, whereas in animals infected with S. brasiliensis the drug did not work.
Five phylogenetically close rice SWEET genes confer TAL effector‐mediated susceptibility to Xanthomonas oryzae pv. oryzae
Authors: Streubel Jana , Pesce Céline , Hutin Mathilde , Koebnik Ralf , Boch Jens , Szurek Boris 
Published: July 2013

Summary

Bacterial plant‐pathogenic Xanthomonas strains translocate transcription activator‐like (TAL) effectors into plant cells to function as specific transcription factors. Only a few plant target genes of TAL effectors have been identified, so far. Three plant SWEET genes encoding putative sugar transporters are known to be induced by TAL effectors from rice‐pathogenic Xanthomonas oryzae pv. oryzae (Xoo).

We predict and validate that expression of OsSWEET14 is induced by a novel TAL effector, Tal5, from an African Xoo strain. Artificial TAL effectors (ArtTALs) were constructed to individually target 20 SWEET orthologs in rice. They were used as designer virulence factors to study which rice SWEET genes can support Xoo virulence.

The Tal5 target box differs from those of the already known TAL effectors TalC, AvrXa7 and PthXo3, which also induce expression of OsSWEET14, suggesting evolutionary convergence on key targets. ArtTALs efficiently complemented an Xoo talC mutant, demonstrating that specific induction of OsSWEET14 is the key target of TalC. ArtTALs that specifically target individual members of the rice SWEET family revealed three known and two novel SWEET genes to support bacterial virulence.

Our results demonstrate that five phylogenetically close SWEET proteins, which presumably act as sucrose transporters, can support Xoo virulence.
Raman spectroscopy as a non‐invasive technique for the quantification of melanins in feathers and hairs
Authors: Galván Ismael , Jorge Alberto , Ito Kazuma , Tabuchi Keisuke , Solano Francisco , Wakamatsu Kazumasa 
Published: July 2013

SummaryThe quantification of melanins is a complex task due to the chemical heterogeneity of the pigments and the difficulty of their isolation. The best accepted procedure currently consists in the chemical cleavage of melanins and the subsequent detection of degradation products by HPLC, which implies the destruction of samples. Here, we show that Raman spectroscopy is a non‐invasive technique that can be used to quantify melanins. We made parallel analyses of the characteristics of pheomelanin and eumelanin Raman spectra as measured by confocal Raman microscopy and of degradation products of pheomelanin (4‐amino‐3‐hydroxyphenylalanine, 4‐AHP) and eumelanin (pyrrole‐2,3,5‐tricarboxylic acid, PTCA) as measured by HPLC in feathers of red‐legged partridges and hairs of wild boars and humans. We found strong correlations between the spectral Raman characteristics and 4‐AHP and PTCA levels, which indicates that the Raman spectra of melanins can be used to determine their content.
Differential Expression of IGF Family Members in Heat‐Stressed Embryos Produced In Vitro from OPU‐Derived Oocytes of Nelore (Bos indicus) and Holstein (Bos taurus) Cows
Authors: Satrapa RA , Razza EM , Castilho ACS , Simões RAL , Silva CF , Nabhan T , Pegorer MF , Barros CM 
Published: July 2013

ContentsThe IGF system is related to embryo quality. We aim to determine the effect of the heat stress on the mRNA expression of IGF1 and IGF2, IGFR1 and IGFR2, IGFBP2 and IGFBP4, and PAPPA in in vitro production (IVP) blastocysts from Nelore and Holstein after ovum pick up (OPU) to better understand the differences between these breeds. Oocytes from four Nelore and seven Holstein were collected in six OPU sessions. Following in vitro maturation and fertilization using six Nelore or Holstein sires, embryos were divided into control (cultured at 39°C) and heat stress (HS; exposed to 41°C for 9 h). Blastocysts were submitted to RNA extraction. The IGF1 expression was higher in blastocysts under HS in both breeds, and the expression of IGFBP2 and IGFBP4 was higher in Holstein blastocysts under HS. The high PAPPA expression and the low expression of IGFBP2 and IGFBP4 are associated with a more efficient degradation of IGFBPs, which results in greater IGF bioavailability in Nelore blastocysts and may contribute to the superior HS tolerance in Nelore, when compared to Holstein.
System Modeling for a Supercritical Thermal Energy Storage System
Authors: Tse Louis , Ganapathi Gani , Wirz Richard , Lavine Adrienne 
Published: July 2013

This paper describes a thermodynamic model that simulates the discharge cycle of a single-tank thermal energy storage (TES) system using supercritical fluid in a concentrating solar power plant.
Current state-of-the-art TES design utilizes a two-tank system with molten nitrate salts; one major problem is the high cost of the fluid. The alternate design explored here involves the use of less expensive fluids at supercritical temperatures and pressures. By cycling the storage fluid between a relatively low temperature two-phase state and a high temperature supercritical state, a large excursion in internal energy can be accessed which includes both sensible heat and latent heat of vaporization.
Supercritical storage allows for the consideration of fluids that are significantly cheaper than molten salts; however, a supercritical TES system requires high pressures and temperatures that necessitate a relatively high cost containment vessel that represents a large fraction of the system capital cost. To mitigate this cost, the proposed design utilizes a single-tank TES system, effectively halving the required wall material. A single-tank approach also significantly reduces the complexity of the system in comparison to the two-tank systems, which require expensive pumps and external heat exchangers. However, a single-tank approach also results in a loss of turbine power output as the storage fluid temperature declines over time during the discharge cycle.
The thermodynamic model is used to evaluate system performance; in particular it predicts the reduction in energy output of the single-tank system relative to a conventional two-tank storage system. Tank wall material volume is also presented and it is shown that there is an optimum average fluid density that generates a given turbine energy output while minimizing the required tank wall material and associated capital cost.
Overall, this study illustrates opportunities to further improve current solar thermal technologies. The single-tank supercritical fluid system shows great promise for decreasing the cost of thermal energy storage, and ensuring that renewable energy can become a significant part of the national and global energy portfolio.
High Density Thermal Energy Storage With Supercritical Fluids
Authors: Ganapathi Gani B. , Wirz Richard 
Published: July 2013

A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures. An additional attraction is that the volumetric storage density of a supercritical fluid can be higher than a two-tank molten salt system due to the high compressibilities in the supercritical state.
This paper looks at different elements for determining the feasibility of this storage concept — thermodynamics of supercritical state with a specific example, naphthalene, fluid and system cost and a representative storage design. A modular storage vessel design based on a shell and heat exchanger concept allows the cost to be minimized as there is no need for a separate pump for transferring fluid from one tank to another as in the molten salt system. Since the heat exchangers are internal to the tank, other advantages such as lower parasitic heat loss, easy fabrication can be achieved.
Results from the study indicate that the fluid cost can be reduced by a factor of ten or even twenty depending on the fluid and thermodynamic optimization of loading factor. Results for naphthalene operating between 290 °C and 475 °C, indicate that the fluid cost is approximately $3/kWh compared with $25-$50/kWh for molten salt. When the storage container costs are factored in, the overall system cost is still very attractive. Studies for a 12-hr storage indicate that for operating at temperatures between 290–450 °C, the cost for a molten salt system can vary between $66/kWh to $184/kWh depending on molten salt cost of $2/kg or a more recent quote of $8/kg. In contrast, the cost for a 12-hr supercritical storage system can be as low as $40/kWh. By using less expensive materials than SS 316L, it is possible to reduce the costs even further.
Screening Tool for the Evaluation of Combined Cooling, Heating, and Power Systems in Existing Office Buildings
Authors: Fumo N. , Mago P. J. , Spencer J. D. 
Published: July 2013

Combined Cooling, Heating, and Power (CCHP) systems have been widely recognized as a key alternative for heat and electricity generation because of their ability to consume fuel more efficiently, which translates into a reduction in carbon dioxide emission, considered the main factor contributing to global warming. However, economic analyses do not always favor the implementation of this technology. Even though CCHP systems offer other benefits such as power reliability, power quality, and fuel source flexibility, they are often negated as a feasible alternative because of these poor economic indicators. Therefore, a more comprehensive evaluation of the system should be considered. This is particularly true in an environment where economic, environmental, political, and logistical problems associated with increasing centralized electrical power production are becoming more difficult to overcome. In addition, as consumers continue to be more involved and to develop a better understanding of energy choices, the demand for technology that better meets their energy needs is increasing.
To promote the development of CCHP projects, it is important to facilitate, without any cost, a first order analysis of this technology to determine if a more cost intensive, in-depth analysis should be performed. This analysis can be done by using screening tools such as the CCHP Screening Tool for Existing Office Buildings (CCHP-ST-EOB) proposed in this study. Screening tools should be as accurate as possible while maintaining the simplicity of their data input in order to make it easy to use by a broad audience that may include building owners and managers without engineering background. In this sense, the CCHP-ST-EOB uses a methodology that translates energy consumption from utility bills as input into hourly energy consumption for a more accurate analysis of the matching between the demand and supply sides. This tool takes into consideration partial load efficiencies for the power generation unit and absorption chiller for a more realistic simulation of the system performance. Results are presented in terms of cost, primary energy consumption, and CO2 emission. The tool is available to be downloaded free of charge at http://microchp.msstate.edu/thankyou.html.
Heliostat Characterization by Optical Techniques and Image Processing
Authors: Peña-Cruz Manuel I. , Arancibia-Bulnes Camilo A. , Iriarte-Cornejo Cuitlahuac , Cabanillas Rafael E. , Estrada Claudio A. 
Published: July 2013

In the framework of the National Laboratory of Solar Concentrating and Solar Chemistry Systems (LACYQS, for its Spanish acronym), a Heliostat Test Field (HTF) was built in México. This research facility is located 10 km away from the city of Hermosillo, in the state of Sonora. The main purpose of the HTF, at the present stage, is to serve as platform for the development and testing of heliostat technology.
In order to evaluate the performance of heliostats, various optical tests have been implemented. In the sun tracking test, the heliostat is operated as a solar tracker. A camera is attached to the heliostat, which is pointed directly to the sun. Images are captured throughout the day to quantify the wandering of the solar disc in the image. In the reflected spot test, the image produced on the Lambertian target by the concentrating heliostat, due to the reflection of the sun, is recorded by a CCD camera throughout the day. Image processing algorithms calculate the centroid of energy of the image and evaluate the position and wandering across the white screen at all times. After this information is gathered, and the influence of wind and external factors eliminated, data are interpreted to characterize the behavior of solar projection algorithms and mechanical components.
In the fringe projection analysis, also known as deflectometry, fringe patters are projected at night on a Lambertian target. The image of the pattern reflected by the heliostat is recorded with a camera. Distortions in the fringes, due to mirror stress and canting, allows the characterization of the surface error of the facets.
The Net Impact of Wind Energy Generation on Emissions of Carbon Dioxide in Texas
Authors: Meehan Colin , Webber Michael , Nagasawa Kazunori 
Published: July 2013

This analysis will examine the relationship between increased levels of wind energy generation and emissions per unit of electricity produced using historical data for electricity output and CO2, SO2 and NOx emissions in the Electric Reliability Council of Texas (ERCOT). Renewable Portfolio Standards (RPS) are generally seen in part as a policy tool for reducing overall system CO2 emissions, although renewable energy goals do not directly regulate such emissions. Limiting this analysis to ERCOT provides two important advantages: transmission of wind energy output is constrained by the physical boundaries of the ERCOT grid, simplifying the analysis and avoiding associated ‘leakage issues’; and ERCOT has the highest level of wind generation as a percentage of total system demand of any grid in the continental U.S.
The intermittent nature of wind generation has resulted in the need to ramp conventional thermal generation up and down to compensate for variability in wind output. Such ramping leads to inefficiencies in many fossil-fueled power plants that increase emissions of CO2, SO2, and NOx relative to a respective unit’s peak efficiency emissions rate.
Using EPA’s Clean Air Markets hourly emissions data, we calculate the total combustion emissions of CO2, SO2 and NOx per MWh of electricity output for the ERCOT system from 2003–2011. The EPA database includes CO2, SO2 and NOx emissions reported by facility owner and operators on an hourly basis in a manner that incorporates facility inefficiencies during ramping periods, allowing us to fully evaluate the CO2 emissions reductions achieved in ERCOT as a result of increased wind generation. The study is ongoing as we wait for emissions statistics from the final quarter of 2011 to be released by the EPA in early 2012.