bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extreme genetic diversity in asexual grass thrips populations
Authors: Fontcuberta García‐Cuenca A. , Dumas Z. , Schwander T. 
Published: February 2016

AbstractThe continuous generation of genetic variation has been proposed as one of the main factors explaining the maintenance of sexual reproduction in nature. However, populations of asexual individuals may attain high levels of genetic diversity through within‐lineage diversification, replicate transitions to asexuality from sexual ancestors and migration. How these mechanisms affect genetic variation in populations of closely related sexual and asexual taxa can therefore provide insights into the role of genetic diversity for the maintenance of sexual reproduction. Here, we evaluate patterns of intra‐ and interpopulation genetic diversity in sexual and asexual populations of Aptinothrips rufus grass thrips. Asexual A. rufus populations are found throughout the world, whereas sexual populations appear to be confined to few locations in the Mediterranean region. We found that asexual A. rufus populations are characterized by extremely high levels of genetic diversity, both in comparison with their sexual relatives and in comparison with other asexual species. Migration is extensive among asexual populations over large geographic distances, whereas close sexual populations are strongly isolated from each other. The combination of extensive migration with replicate evolution of asexual lineages, and a past demographic expansion in at least one of them, generated high local clone diversities in A. rufus. These high clone diversities in asexual populations may mimic certain benefits conferred by sex via genetic diversity and could help explain the extreme success of asexual A. rufus populations.
Pollinator‐mediated assemblage processes in California wildflowers
Authors: Briscoe Runquist R. , Grossenbacher D. , Porter S. , Kay K. , Smith J. 
Published: February 2016

AbstractCommunity assembly is the result of multiple ecological and evolutionary forces that influence species coexistence. For flowering plants, pollinators are often essential for plant reproduction and establishment, and pollinator‐mediated interactions may influence plant community composition. Here, we use null models and community phylogenetic analyses of co‐occurrence patterns to determine the role of pollinator‐mediated processes in structuring plant communities dominated by congeners. We surveyed three species‐rich genera (Limnanthes, MimulusandClarkia) with centres of diversity in the Sierra Nevada of California. Each genus contains species that co‐flower and share pollinators, and each has a robust phylogeny. Within each genus, we surveyed 44–48 communities at three spatial scales, measured floral and vegetative traits and tested for segregation or aggregation of: (i) species, (ii) floral traits (which are likely to be influenced by pollinators), and (iii) vegetative traits (which are likely affected by other environmental factors). We detected both aggregation and segregation of floral traits that were uncorrelated with vegetative trait patterns; we infer that pollinators have shaped the community assembly although the mechanisms may be varied (competition, facilitation, or filtering). We also found that mating system differences may play an important role in allowing species co‐occurrence. Together, it appears that pollinators influence community assemblage in these three clades.
P–T–t evolution of garnet amphibolites in the Wutai–Hengshan area, North China Craton: insights from phase equilibria and geochronology
Authors: Qian J. H. , Wei C. J. 
Published: February 2016

AbstractGarnet amphibolites can provide valuable insights into geological processes of orogenic belts, but their metamorphic evolution is still poorly constrained. Garnet amphibolites from the Wutai–Hengshan area of the North China Craton mainly consist of garnet, hornblende, plagioclase, quartz, rutile and ilmenite, with or without titanite and epidote. Four samples selected in a south–north profile were studied by the pseudosection approach in order to elucidate the characteristics of their metamorphic evolution, and to better reveal the northwards prograde change in P–T conditions as established previously. For the sample from the lower Wutai Subgroup, garnet exhibits obvious two‐substage growth zoning characteristic of pyrope (Xpy) increasing but grossular (Xgr) decreasing outwards in the core, and both Xpy and Xgr increasing outwards in the rim. Phase modelling using thermocalc suggests that the garnet cores were formed by chlorite breakdown over 7–9 kbar at 530–600 °C, and rims grew from hornblende and epidote breakdown over 9.5–11.5 kbar at 600–670 °C. The isopleths of the minimum An in plagioclase and maximum Xpy in garnet were used to constrain the peak P–T conditions of ~11.5 kbar/670 °C. The modelled peak assemblage garnet + hornblende + epidote+ plagioclase + rutile + quartz matches well the observed one. Plagioclase–hornblende coronae around garnet indicate post‐peak decompression and fluid ingress. For the samples from the south Hengshan Complex, the garnet zoning weaken gradually, reflecting modifications during decompression of the rocks. Using the same approach, the rocks are inferred to have suprasolidus peak conditions, increasing northwards from 11.5 kbar/745 °C, 12.5 kbar/780 °C to 13 kbar/800 °C. Their modelled peak assemblages involve diopside, garnet, hornblende, plagioclase, rutile and quartz, yet diopside is not observed petrographically. The post‐peak decompression is characterized by diopside + garnet + quartz + melt = hornblende + plagioclase, causing the diopside consumption and garnet compositions to be largely modified. Thus, the pesudosection approach is expected to provide better pressure results than conventional thermobarometry, because the later approach cannot be applied with confidence to rocks with multi‐generation assemblages. U–Pb dating of zircon in the Wutai sample records a protolith age of c. 2.50 Ga, and a metamorphic age of c. 1.95 Ga, while zircon in the Hengshan samples records metamorphic ages of c. 1.92 Ga. The c. 1.95 Ga is interpreted to represent the pre‐peak or peak metamorphic stages, and the ages of c. 1.92 Ga are assigned to represent the cooling stages. All rocks in the Wutai–Hengshan area share similar clockwise P–T morphologies. They may represent metamorphic products at different crustal depths in one orogenic event, which included a main thickening stage at c. 1.95 Ga followed by a prolonged uplift and cooling after 1.92 Ga.
Periodontal Conditions of Abutments and Non‐Abutments in Removable Partial Dentures over 7 Years of Use
Authors: da Fonte Porto Carreiro Adriana , de Carvalho Dias Kássia , Correia Lopes Ana Lílian , Bastos Machado Resende Camila Maria , Luz de Aquino Martins Ana Rafaela 
Published: February 2016

AbstractPurposeTo evaluate the periodontal conditions and integrity of abutment and non‐abutment teeth of patients evaluated 7 years after insertion of the removable partial denture (RPD).Materials and MethodsTwenty‐two patients (17 women, 5 men) were assessed at the moment of denture insertion and 7 years later. The following items were verified in each assessment: bleeding on probing (BP), probing depth (PD), gingival recession (GR), and mobility (M), comparing direct and indirect abutment teeth, and the teeth not involved in the denture design. Tooth integrity was also evaluated and classified as intact when no caries or fractures were observed. The Kruskal‐Wallis test was used to reveal statistical significance between the groups (p = 0.05) as well as the Bonferrroni‐corrected Mann‐Whitney test for post hoc comparison. The Wilcoxon test was used for evaluation within the group over time. Fisher's exact test was applied to cross data about abutment integrity.ResultsStatistically significant differences were found for GR (baseline, p < 0.001; 7 years, p < 0.001) and PD (baseline, p = 0.001; 7 years = 0.004) between the three groups at baseline and after 7 years of follow‐up. Mean BP and M values increased from initial assessment to after 7 years of RPD use in every group, but no statistically significant difference was found between the groups. For abutment integrity, a statistically significant difference (p = 0.028) was observed, and the direct abutment exhibited more (33.3%) caries and fractures.ConclusionRPDs generated more periodontal damage to direct abutments, since higher gingival recession probing depth indexes, and presence of caries and fractures were observed in comparison to indirect abutments and non‐abutments.
Elevated interleukin‐8 in bile of patients with primary sclerosing cholangitis
Authors: Zweers Serge J. , Shiryaev Alexey , Komuta Mina , Vesterhus Mette , Hov Johannes R. , Perugorria María J. , de Waart D. Rudi , Chang Jung‐Chin , Tol Shanna , te Velde Anje A. , de Jonge Wouter J. , Banales Jesus M. , Roskams Tania , Beuers Ulrich , Karlsen Tom H. , Jansen Peter L. , Schaap Frank G. 
Published: February 2016

AbstractBackground & AimsTo better understand the pathogenesis of primary sclerosing cholangitis, anti‐ and pro‐inflammatory factors were studied in bile.MethodsDuctal bile of PSC patients (n = 36) and controls (n = 20) was collected by endoscopic retrograde cholangiography. Gallbladder bile was collected at liver transplantation. Bile samples were analysed for cytokines, FGF19 and biliary lipids. Hepatobiliary tissues of PSC and non‐PSC patients (n = 8–11 per patient group) were collected at transplantation and were analysed for IL8 and FGF19 mRNA expression and IL8 localization. The effect of IL8 on proliferation of primary human cholangiocytes and expression of pro‐fibrotic genes was studied.ResultsIn PSC patients, median IL8 in ductal bile was 6.6 ng/ml vs. 0.24 ng/ml in controls. Median IL8 in gallbladder bile was 7.6 ng/ml in PSC vs. 2.2 and 0.3 ng/ml in two control groups. IL8 mRNA in PSC gallbladder was increased and bile ducts stained positive for IL8. In vitro, IL8 induced proliferation of primary human cholangiocytes and increased the expression of pro‐fibrotic genes.ConclusionElevation of IL8 in bile of PSC patients, collected at different stages of disease, indicates an ongoing inflammatory stimulus that drives IL8 production. This challenges the idea that advanced PSC is a burned‐out disease, and calls for reconsideration of anti‐inflammatory therapy in PSC.
Regulation of UVR8 photoreceptor dimer/monomer photo‐equilibrium in Arabidopsis plants grown under photoperiodic conditions
Authors: Findlay Kirsten M.W. , Jenkins Gareth I. 
Published: February 2016

AbstractThe UV RESISTANCE LOCUS 8 (UVR8) photoreceptor specifically mediates photomorphogenic responses to UV‐B. Photoreception induces dissociation of dimeric UVR8 into monomers to initiate responses. However, the regulation of dimer/monomer status in plants growing under photoperiodic conditions has not been examined. Here we show that UVR8 establishes a dimer/monomer photo‐equilibrium in plants growing in diurnal photoperiods in both controlled environments and natural daylight. The photo‐equilibrium is determined by the relative rates of photoreception and dark‐reversion to the dimer. Experiments with mutants in REPRESSOR OF UV‐B PHOTOMORPHOGENESIS 1 (RUP1) and RUP2 show that these proteins are crucial in regulating the photo‐equilibrium because they promote reversion to the dimer. In plants growing in daylight, the UVR8 photo‐equilibrium is most strongly correlated with low ambient fluence rates of UV‐B (up to 1.5 μmol m−2 s−1), rather than higher fluence rates or the amount of photosynthetically active radiation. In addition, the rate of reversion of monomer to dimer is reduced at lower temperatures, promoting an increase in the relative level of monomer at approximately 8–10 °C. Thus, UVR8 does not behave like a simple UV‐B switch under photoperiodic growth conditions but establishes a dimer/monomer photo‐equilibrium that is regulated by UV‐B and also influenced by temperature.
Unobserved Heterogeneity, Exit Rates, and Re‐Employment Wages
Authors: Fernández‐Blanco Javier , Gomes Pedro 
Published: February 2016

AbstractExit rates from unemployment and re‐employment wages decline over a period of unemployment, after controlling for worker observable characteristics. We study the role of unobserved heterogeneity in an economy with asymmetric information and directed search. We show that the unique equilibrium is separating and that skilled workers have more job opportunities and higher wages. The composition of the unemployed varies with the duration of unemployment, so average exit rates and wages fall with time. The separating equilibrium relies on performance‐related pay schemes and the ability of firms to commit to renting an input that is complementary to worker skills.
Cyclic movement frequency is associated with muscle typology in athletes
Authors: Bex T. , Baguet A. , Achten E. , Aerts P. , De Clercq D. , Derave W. 
Published: February 2016

There is a continuing research interest in the muscle fiber type composition (MFTC) of athletes. Recently, muscle carnosine quantification by proton magnetic resonance spectroscopy (1H‐MRS) was developed as a new non‐invasive method to estimate MFTC. This cross‐sectional study aims to better understand estimated MFTC in relation to (a) different disciplines within one sport; (b) cyclic sport exercise characteristics; (c) within‐athlete variability; and (d) athlete level. A total of 111 elite athletes (74 runners, 7 triathletes, 11 swimmers, 14 cyclists and 5 kayakers) and 188 controls were recruited to measure muscle carnosine in gastrocnemius and deltoid muscle by 1H‐MRS. Within sport disciplines, athletes were divided into subgroups (sprint‐, intermediate‐, and endurance‐type). The controls were used as reference population to allow expression of the athletes’ data as Z‐scores. Within different sports, endurance‐type athletes systematically showed the lowest Z‐score compared to sprint‐type athletes, with intermediate‐type athletes always situated in between. Across the different sports disciplines, carnosine content showed the strongest significant correlation with cyclic movement frequency (R = 0.86, P = 0.001). Both within and between different cyclic sports, estimated MFTC was divergent between sprint‐ and endurance‐type athletes. Cyclic movement frequency, rather than exercise duration came out as the most determining factor for the optimal estimated MFTC in elite athletes.
Electrical synapses and the development of inhibitory circuits in the thalamus
Authors: Zolnik Timothy A. , Connors Barry W. 
Published: February 2016

Key points
The thalamus is a structure critical for information processing and transfer to the cortex.
Thalamic reticular neurons are inhibitory cells interconnected by electrical synapses, most of which require the gap junction protein connexin36 (Cx36).
We investigated whether electrical synapses play a role in the maturation of thalamic networks by studying neurons in mice with and without Cx36.
When Cx36 was deleted, inhibitory synapses were more numerous, although both divergent inhibitory connectivity and dendritic complexity were reduced. Surprisingly, we observed non‐Cx36‐dependent electrical synapses with unusual biophysical properties interconnecting some reticular neurons in mice lacking Cx36.
The results of the present study suggest an important role for Cx36‐dependent electrical synapses in the development of thalamic circuits.
AbstractNeurons within the mature thalamic reticular nucleus (TRN) powerfully inhibit ventrobasal (VB) thalamic relay neurons via GABAergic synapses. TRN neurons are also coupled to one another by electrical synapses that depend strongly on the gap junction protein connexin36 (Cx36). Electrical synapses in the TRN precede the postnatal development of TRN‐to‐VB inhibition. We investigated how the deletion of Cx36 affects the maturation of TRN and VB neurons, electrical coupling and GABAergic synapses by studying wild‐type (WT) and Cx36 knockout (KO) mice. The incidence and strength of electrical coupling in TRN was sharply reduced, but not abolished, in KO mice. Surprisingly, electrical synapses between Cx36‐KO neurons had faster voltage‐dependent decay kinetics and conductance asymmetry (rectification) than did electrical synapses between WT neurons. The properties of TRN‐mediated inhibition in VB also depended on the Cx36 genotype. Deletion of Cx36 increased the frequency and shifted the amplitude distributions of miniature IPSCs, whereas the paired‐pulse ratio of evoked IPSCs was unaffected, suggesting that the absence of Cx36 led to an increase in GABAergic synaptic contacts. VB neurons from Cx36‐KO mice also tended to have simpler dendritic trees and fewer divergent inputs from the TRN compared to WT cells. The findings obtained in the present study suggest that proper development of thalamic inhibitory circuitry, neuronal morphology, TRN cell function and electrical coupling requires Cx36. In the absence of Cx36, some TRN neurons express asymmetric electrical coupling mediated by other unidentified connexin subtypes.
Numerical Investigation on Effect of Aspect Ratio of Axisymmetric Circumferential Groove Casing Treatment Coupled to a Transonic Axial Flow Compressor Stage
Authors: Mehta Nishit J. , Alone Dilipkumar Bhanudasji , Choksi Harish S. 
Published: February 2016

While the effects of axisymmetric casing treatment on performance of an axial compressor stage have been extensively studied numerically as well as experimentally, the major geometrical parameters which govern these effects have been identified. Studies are now focused on understanding how each of these parameters individually impacts the performance of a casing treatment.
The present work aims to study the impact on performance of casing treatment geometry when aspect ratio of the grooves is varied in a circumferential groove casing treatment. The compressor geometry chosen for this study has design characteristics of a transonic compressor stage. Flow field solutions were derived for baseline model by solving steady state 3-D Reynolds-Averaged Navier-Stokes (RANS) equations for three grid densities and the grid independence was proved. The basic casing treatment geometry has 10 circumferential grooves of width 4mm and axial spacing of 2mm between each groove. The aspect ratio was varied by changing the depth of the grooves in each case. These casing treatment geometries were superimposed over the rotor domain with the grooves extending over the entire blade tip chord and flow field solutions were again obtained for various aspect ratios of grooves.
These results depict improvement in the range of operation in terms of mass flow rate. Results also show that the aspect ratio of the grooves significantly influences the overall effectiveness of casing treatment on the performance of compressor stage. Improvement in overall compressor efficiency is noted with lower aspect ratio casing treatments when compared to those with higher aspect ratios, however, the range improvement is higher with higher aspect ratios. It is also observed that, after a certain depth of grooves is reached, there is no significant improvement in performance on further increasing the depth and hence the aspect ratio.
Post processing results of the flow solutions are presented which confirm the trends and show that the flow behavior near rotor tip governs this effect.
Shape Optimization of Flexible Supports for Aero Engines
Authors: Gnanasundaram Govindaraji , Setty Srinath , Kasina Lakshman , Kotur Raghavan 
Published: February 2016

Flexible supports are used in many aero and automobile industrial applications. They transmit loads, accommodate misalignment, allow axial displacement, ensure no loss of lubricants, absorb shock and dampen vibration, withstand high temperatures, allow easy installation and disassembling. Flexible supports react on connected equipment components when subjected to misalignment and torque. The reaction forces and moments on components due to flexible supports should be within the allowable limits or otherwise it can cause failure of gears, shafts, bearings, and other equipment components.
These flexible supports used in aero engine applications expected to meet design and manufacturing criteria. Flexible supports should have required stiffness values in different directions to meet rotor dynamic stability criteria. Flexible supports also required to meet strength and durability criteria for the given material at the required maximum operating temperature. The designed component should be producible and meet manufacturing limitations.
The main objective of this paper is to optimize single and multiple convolutes types of flexible supports with in the manufacturing limits and in the given design space. A methodology is developed to optimize the components to meet required stiffness, strength and durability criteria. Parametric models of flexible support are developed in UNIGRAPHICS NX9. Design parameters such as overall length, convolute height, convolute radius and angle are considered for the optimization study. ANSYS Workbench is used for the analysis and optimization of flexible support.
Performance Prediction of Darrieus Turbine Through Numerical Analysis
Authors: Mukherjee Prasenjit , Saha Ujjwal K. 
Published: February 2016

With the rising fossil-fuel prices, energy scarcity and climate-change, renewable energy plays an important role in producing local, clean and inexhaustible energy source to supply world rising demand for electricity. The selection of suitable wind turbine plays a vital role for urban power generation where wind is characterised by unsteadiness and turbulence. Thus, blade aerodynamics of wind turbine has a significant effect on turbine efficiency.
In this study, the aerodynamic aspect of a straight bladed Darrieus turbine is numerically analyzed. Two dimensional numerical modelling and simulation of unsteady flow through the rotor blades (NACA 0018) of the turbine is performed using ANSYS FLUENT 14.5. The unsteady Reynolds averaged Navier-Stokes (RANS) equation is used to demonstrate the effects on the performance of two dimensional Darrieus turbine blade. The Shear Stress Transport (SST) k-ω model has been adopted for the turbulence closure. For the proposed analysis, the flow field characteristics are investigated at different azimuthal angle and tip speed ratio. Further, the parametric quantities such as solidity, number of blades and blade thickness have being investigated for a uniform free stream velocity of 6 m/s. The effect of laminar boundary layer separation on performance of the Darrieus turbine has also been taken into account during the study of flow physics around the blade. The results obtained are compared with the reported experimental and computational data.