bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divergent warning patterns contribute to assortative mating between incipient Heliconius species
Authors: Merrill Richard M. , Chia Audrey , Nadeau Nicola J. 
Published: February 2014

AbstractTheoretical models suggest that traits under divergent ecological selection, which also contribute to assortative mating, will facilitate speciation with gene flow. Evidence for these so‐called “magic traits” now exists across a range of taxa. However, their importance during speciation will depend on the extent to which they contribute to reproductive isolation. Addressing this requires experiments to determine the exact cues involved as well as estimates of assortative mating in the wild. Heliconius butterflies are well known for their diversity of bright warning color patterns, and their amenability to experimental manipulation has provided an excellent opportunity to test their role in reproductive isolation. Here, we reveal that divergent color patterns contribute to mate recognition between the incipient species Heliconius himera and H. erato, a taxon pair for which assortative mating by color pattern has been demonstrated among wild individuals: First, we demonstrate that males are more likely to attempt to mate conspecific females; second, we show that males are more likely to approach pinned females that share their own warning pattern. These data are valuable as these taxa likely represent the early stages of speciation, but unusually also allow comparisons with rates of interbreeding between divergent ecologically relevant phenotypes measured in the wild.
Sex‐specific cardiovascular structure and function in heart failure with preserved ejection fraction
Authors: Gori Mauro , Lam Carolyn S. P. , Gupta Deepak K. , Santos Angela B. S. , Cheng Susan , Shah Amil M. , Claggett Brian , Zile Michael R. , Kraigher‐Krainer Elisabeth , Pieske Burkert , Voors Adriaan A. , Packer Milton , Bransford Toni , Lefkowitz Martin , McMurray John J. V. , Solomon Scott D. ,   for the PARAMOUNT Investigators
Published: February 2014

AimsWomen are more likely to develop heart failure with preserved ejection fraction (HFpEF) than men. We studied the relationship between sex and cardiovascular structure and function in patients with HFpEF.Methods and resultsThe study included 279 participants from the PARAMOUNT study (57% women) with analysable baseline echocardiograms (mean age 71 years, 94% hypertensive, 38% diabetic). We assessed sex‐based differences in baseline clinical characteristics and measures of cardiovascular structure/function. Coronary artery disease was less common in women than in men. Women were more obese and symptomatic, and less likely to have albuminuria. Women had higher indexed left ventricular (LV) wall thicknesses, worse diastolic function (lower E′, P = 0.002; higher E/E′, P < 0.001), while LV mass and LV volumes indexed for height2.7 were similar. Nonetheless, female sex was associated with a trend towards higher prevalence of abnormal LV geometry (defined as concentric hypertrophy, or eccentric hypertrophy, or concentric remodelling) at baseline (unadjusted P = 0.028, adjusted P = 0.056) and 12 weeks' follow up (unadjusted P = 0.001, adjusted P = 0.006), but not at 36 weeks' follow up (unadjusted P = 0.81, adjusted P = 0.99). Despite higher LV ejection fraction in women, global LV strain was similar between the sexes, while Tissue Doppler Imaging S′ mitral velocity was lower in women. Both LV diastolic and systolic stiffness were higher in women than men (P < 0.001), even adjusting for LV concentricity and clinical covariates. We observed no sex differences in systolic arterial–LV coupling, as women also had higher absolute arterial elastance compared with men, although this difference was not significant after adjusting for height2.7.ConclusionMore pronounced diastolic dysfunction may contribute to the greater predisposition for HFpEF in women compared with men.
Rational Design of Ligand Precursors to Prepare Abnormal (Mesoionic) and Normal Carbene Complexes and Zwitterionic CX‐Type Palladacycles (X = C, N)
Authors: Chen Shih‐Ji , Lin Yuan‐Deng , Chiang Yen‐Hsin , Lee Hon Man 
Published: February 2014

AbstractThe preparation of a series of ligand precursors that feature imidazo[1,2‐a]pyridine and amido functional groups is reported. The reactions between the new ligand precursors, pyridine, and palladium acetate in DMF afforded monodentate PdII abnormal (mesoionic) carbene complexes. An isomeric PdII normal carbene complex with a formally identical steric environment to that of the abnormal carbene counterpart was also prepared. The isomeric pairs were characterized by X‐ray structural studies. Under different complexation conditions, in which PdCl2 was employed as metal precursor, a zwitterionic CC‐type palladacycle formed by the C–H activation at the ortho‐N‐phenyl and methylene carbon atoms was obtained. The use of a similar ligand precursor with an NH instead of an NMe group produced a zwitterionic palladalactam complex. In contrast to the previous work in the literature, owing to the rigidity of the fused heterocyclic ring, the palladalactam complex did not undergo intramolecular proton transfer through the coordinated N atom. Overall, we demonstrated that proper modification of the structures of ligand precursors and complexation conditions allowed us to obtain a full range of intriguing PdII complexes including normal and abnormal carbene complexes, and zwitterionic palladalactam and CC‐type palladacycles by means of A–H bond (A = N, C) activations.
Bridging the Gap: Attractive 3c–4e Interactions in peri‐Substituted Acenaphthylenes
Authors: Diamond Louise M. , Knight Fergus R. , Athukorala Arachchige Kasun S. , Randall Rebecca A. M. , Bühl Michael , Slawin Alexandra M. Z. , Woollins J. Derek 
Published: February 2014

AbstractA series of peri‐substituted acenaphthylenes that contain mixed halogen–chalcogen functionalities at the 5,6‐positions in 1–6 [Acenapyl[X](EPh) (Acenapyl = acenaphthylene‐5,6‐diyl; X = Br, I; E = S, Se, Te)] and chalcogen–chalcogen moieties in 7–11 [Acenap(EPh)(E′Ph) (Acenap = acenaphthene‐5,6‐diyl; E/E′ = S, Se, Te)] have been prepared from their corresponding acenaphthene analogues A1–A11 by utilising 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) for the dehydrogenation of the ethane backbone. The related dihalide compounds 13 and 14 Acenapyl[XX′] (XX′ = BrBr, II) have also been prepared by following a similar procedure, and 1,2,5,6‐tetrabromo‐1,2‐dihydroacenaphthylene A0 was prepared as an intermediate by following an alternative route to 13. The series of acenaphthylene compounds have remarkably similar molecular structures to their acenaphthene counterparts; they exhibit an expected increase in peri separation as heavier congeners occupy the close peri positions. The presence of the ethene bridge, however, naturally compresses the nearest bay angle as it increases the splay of the exocyclic peri atoms, thereby resulting in a minor increase in separation relative to equivalent acenaphthenes. The structures of 1–11, 13 and 14 are discussed and compared with previously reported analogous naphthalene and acenaphthene compounds. Similar to acenaphthene derivatives, aromatic ring conformations and the location of p‐type lone pairs influences the geometry of the peri region. Under appropriate geometric conditions, quasi‐linear three‐body CPh–E···Z (E = Te, Se, S; Z = Br/E) fragments provide an attractive component for the E···Z interaction. DFT studies confirm the onset of formation of three‐center, four‐electron bonding, similar in extent to that observed in analogous acenaphthenes, despite an increase in the peri distances.
Baker's‐Yeast‐Mediated Reduction of Sulfur‐Containing Compounds
Authors: Deasy Rebecca E. , Maguire Anita R. 
Published: February 2014

AbstractBoth the efficiency and the stereoselectivity in baker's‐yeast‐mediated reduction of ketones are strongly influenced by both the presence and the position of sulfur substituents, or indeed by the use of sulfur‐containing additives. Interestingly the oxidation level of the sulfur substituent has a powerful impact on the outcome of the yeast reduction. It is apparent that use of the sulfone moiety as a substituent to influence the efficiency and stereoselectivity in ketone reduction is substantially more effective than use of the analogous sulfide and sulfoxide moieties.
A One‐Pot Oxidation/Enantioselective Oxa‐Michael Cascade
Authors: Willemsen Jorgen S. , Megens Rik P. , Roelfes Gerard , van Hest Jan C. M. , Rutjes Floris P. J. T. 
Published: February 2014

AbstractA laccase/(2,2,6,6‐tetramethylpiperidin‐1‐yl)oxy (TEMPO) mediated oxidation was combined with an aqueous, enantioselective copper‐catalyzed Michael addition reaction of water in one pot. The copper catalyst was also immobilized onto DNA to induce enantioselectivity in the reaction. Low conversions were observed when the reactions were performed simultaneously, caused by an undesired reaction of an oxidised TEMPO intermediate. We increased the conversions by using a stepwise approach. Thus, after completion of the oxidation, the first reaction was stopped by inhibiting the enzyme with HCO2K and reducing the reactive TEMPO intermediate. Next, the Michael addition reaction was started by adding the Cu catalyst. By applying this strategy, an efficient two‐step one‐pot sequence, proceeding with 20 % ee, was realized. The yield and ee of the second reaction were not affected by the oxidation reaction.
Integrating climate and local factors for geomorphological distribution models
Authors: Aalto Juha , Luoto Miska 
Published: February 2014

ABSTRACTEarth surface processes (ESPs) drive landscape development and ecosystem processes in high‐latitude regions by creating spatially heterogeneous abiotic and biotic conditions. Ongoing global change may potentially alter the activity of ESPs through feedback on ground conditions, vegetation and the carbon cycle. Consequently, accurate modeling of ESPs is important for improving understanding of the current and future distributions of these processes. The aims of this study were to: (1) integrate climate and multiple local predictors to develop realistic ensemble models for the four key ESPs occurring at high latitudes (slope processes, cryoturbation, nivation and palsa mires) based on the outputs of 10 modern statistical techniques; (2) test whether models of ESPs are improved by incorporating topography, soil and vegetation predictors to climate‐only models; (3) examine the relative importance of these variables in a multivariate setting. Overall, the models showed high transferability with the mean area under curve of a receiver operating characteristics (AUC) ranging from 0.83 to 0.96 and true skill statistics (TSS) from 0.52 to 0.87 for the most complex models. Even though the analyses highlighted the importance of the climate variables as the most influential predictors, three out of four models benefitted from the inclusion of local predictors. We conclude that disregarding local topography and soil conditions in spatial models of ESPs may cause a significant source of error in geomorphological distribution models. Copyright © 2014 John Wiley & Sons, Ltd.
Stemflow production and intrastorm rainfall intensity variation: an experimental analysis using laboratory rainfall simulation
Authors: Dunkerley David 
Published: February 2014

ABSTRACTLaboratory rainfall simulation experiments using a small artificial olive tree are used to show that the fraction of rain falling at a constant intensity that becomes stemflow rises from 9% at 2.5 mm/h to 36.1% at 35 mm/h. Natural rainfall events commonly exhibit wide fluctuations of intensity. Simulated rainfall events each having a mean intensity of 10 mm/h, but containing short intensity peaks of 20 to 100 mm/h at varying intra‐event positions, were used to explore the effect of varying intensity profiles. Results demonstrate that changes in rainfall event profile are associated with wide variation in stemflow flux, stemflow volume and stemflow fraction. When applied to an initially dry plant, rainfall events with a late intensity peak yielded an average peak stemflow flux up to 188% larger than events of contrasting profile, such as early peak events. The increase was smaller, up to 141%, when rain was applied to plants that were already partially wet, but was again found in events with a late intensity peak. Moreover, such events yielded a peak stemflow flux up to approximately seven times larger than comparable events of uniform intensity. Likewise, changing event profile with no change in rainfall depth was associated with a maximum stemflow fraction that was 31% larger than theminimum stemflow fraction, and a maximum stemflow volume that was nearly 37% larger than the minimum stemflow volume. These results suggest that rainfall event profile exerts a significant effect on all of the studied stemflow parameters. It is hypothesized that this is a consequence of the way in which intensity profile affects the rate of wetting‐up of trickle pathways on the plant, and variation in the time taken for these pathways to become fully connected. Event profile must therefore be considered along with plant architecture in seeking to understand stemflow. Copyright © 2014 John Wiley & Sons, Ltd.
Do not only connect: a model of infiltration‐excess overland flow based on simulation
Authors: Kirkby Michael J. 
Published: February 2014

ABSTRACTThe paper focusses on connectivity in the context of infiltration‐excess overland flow and its integrated response as slope‐base overland flow hydrographs. Overland flow is simulated on a sloping surface with some minor topographic expression and spatially differing infiltration rates. In each cell of a 128 × 128 grid, water from upslope is combined with incident rainfall to generate local overland flow, which is stochastically routed downslope, partitioning the flow between downslope neighbours.Simulations show the evolution of connectivity during simple storms. As a first approximation, total storm runoff is similar everywhere, discharge increasing proportionally with drainage area. Moderate differences in plan topography appear to have only a second‐order impact on hydrograph form and runoff amount.Total storm response is expressed as total runoff, runoff coefficient or total volume infiltrated; each plotted against total storm rainfall, and allowing variations in average gradient, overland flow roughness, infiltration rate and storm duration. A one‐parameter algebraic expression is proposed that fits simulation results for total runoff, has appropriate asymptotic behaviour and responds rationally to the variables tested. Slope length is seen to influence connectivity, expressed as a scale distance that increases with storm magnitude and can be explicitly incorporated into the expression to indicate runoff response to simple events as a function of storm size, storm duration, slope length and gradient.The model has also been applied to a 10‐year rainfall record, using both hourly and daily time steps, and the implications explored for coarser scale models. Initial trails incorporating erosion continuously update topography and suggest that successive storms produce an initial increase in erosion as rilling develops, while runoff totals are only slightly modified. Other factors not yet considered include the dynamics of soil crusting and vegetation growth. Copyright © 2014 John Wiley & Sons, Ltd.
Achieving high data rates through full duplex relaying in multicell environments
Authors: Sharma Prabhat Kumar , Garg Parul 
Published: February 2014

AbstractIn this paper, we investigate the outage and error performances of a full duplex relaying cooperative system in a multicell environment, considering the possibility of co‐channel interference from the users located in the nearby cells. The decode‐and‐forward cooperative strategy is assumed at the relay. Throughout the analysis, we consider all the channels to be independent but not necessarily identically distributed as generalised Nakagami‐m fading. We find an accurate closed‐form expression of outage probability and average symbol error rate for integer values of fading parameter m. The analysis considers symmetric M‐ary phase shift keying modulation scheme with equal energy constellation. Copyright © 2014 John Wiley & Sons, Ltd.
Performance Analysis of PEM Fuel Cells with Different Electrical Loads
Authors: San Martín J. I. , Zamora I. , Aperribay V. , San Martín J. J. , Eguía P. , Torres E. 
Published: February 2014

AbstractOne of the most outstanding products of fuel cells is electrical power but, currently, there is a reduced number of publications that provide experimental data about the performance of fuel cells when used for supplying Alternating Current (AC) loads. Most of the existing publications provide experimental data only with direct current (DC) loads, or analyze the performance with AC loads using simulation models. For this reason, this paper analyses experimentally the behavior of a proton exchange membrane fuel cell (PEMFC) system when feeding different electrical loads. The system tested is constituted by a PEM fuel cell, a storage battery, electronic converters and electrical loads. In the tests, the fuel cell system supplies power to three different loads: DC, single‐phase AC and three‐phase AC. For these cases, voltage, current, power, power factor and efficiency data are shown, at different load levels. From those parameters, efficiency of the global system is estimated. Finally, as the power quality concept is a topic of increasing importance when supplying electricity, the total harmonic distortion (THD) of the electric signals has also been analyzed.
A comparison of dual gradient‐echo and spin‐echo fMRI of the inferior temporal lobe
Authors: Halai Ajay D , Welbourne Stephen R , Embleton Karl , Parkes Laura M 
Published: February 2014

AbstractMagnetic susceptibility differences at tissue interfaces lead to signal loss in conventional gradient‐echo (GE) EPI. This poses a problem for fMRI in language and memory paradigms, which activate the most affected regions. Two methods proposed to overcome this are spin‐echo EPI and dual GE EPI, where two EPI read‐outs are serially collected at a short and longer echo time. The spin‐echo method applies a refocusing pulse to recover dephased MR signal due to static field inhomogeneities, but is known to have a relatively low blood oxygenation level dependant (BOLD) sensitivity. In comparison, GE has superior BOLD sensitivity, and by employing an additional shorter echo, in a dual GE sequence, it can reduce signal loss due to spin dephasing. We directly compared dual GE and spin‐echo fMRI during a semantic categorization task, which has been shown to activate the inferior temporal region—a region known to be affected by magnetic susceptibility. A whole brain analysis showed that the dual GE resulted in significantly higher activation within the left inferior temporal fusiform (ITF) cortex, compared to spin‐echo. The inferior frontal gyrus (IFG) was activated for dual GE, but not spin‐echo. Regions of interest analysis was carried out on the anterior and posterior ITF, left and right IFG, and part of the cerebellum. Dual GE outperformed spin‐echo in the anterior and posterior ITF and bilateral IFG regions, whilst being equal in the cerebellum. Hence, dual GE should be the method of choice for fMRI studies of inferior temporal regions. Hum Brain Mapp 35:4118–4128, 2014. © 2014 Wiley Periodicals, Inc.
The heart‐rate‐reducing agent, ivabradine, reduces mechanical allodynia in a rodent model of neuropathic pain
Authors: Noh S. , Kumar N. , Bukhanova N. , Chen Y. , Stemkowsi P.L. , Smith P.A. 
Published: February 2014

AbstractBackgroundPeripheral nerve injury increases the excitability of primary sensory neurons. This triggers the onset of neuropathic pain and maintains its persistence. Because changes in hyperpolarization‐activated cyclic nucleotide‐gated cation (HCN) channels are implicated in this process, we examined the action of the heart‐rate‐reducing agent, ivabradine, a clinically approved HCN blocker, in the rat chronic constriction injury (CCI) model of neuropathic pain.MethodsThe effects of ivabradine on mechanical allodynia were assessed using von Frey filaments, and the effects on cardiovascular parameters were monitored by telemetry. Ivabradine block of HCN channels in dorsal root ganglion neurons was confirmed by whole‐cell recording.ResultsIn rats subject to CCI, ivabradine (6 mg/kg by gavage twice a day) significantly reduced mechanical allodynia. Cumulative effects were seen with twice daily oral administration over a 4‐day period. Allodynia returned 4 days after the final drug dose. Mean arterial pressure was maintained and only a 15% pharmacological reduction in heart rate was observed. There was no cumulative effect of ivabradine on cardiovascular parameters.ConclusionBecause ivabradine is effective at an oral dose that produces only moderate pharmacological heart rate reduction, and this is known to be well tolerated in a clinical context, these results underline its possible use in neuropathic pain management.
Differential antinociceptive effects of intrathecal administration of C‐terminal esterified endomorphin‐2 analogues in mice
Authors: Wang C.L. , Xiang Q. , Diao Y.X. , Ren Y.K. , Gu N. 
Published: February 2014

AbstractBackgroundWe have previously synthesized three esterified endomorphin‐2 (EM‐2) analogues 1–3 by substitution of C‐terminus with methyl, ethyl and tert‐butyl ester, respectively. Interestingly, the increase of EM‐2 in bulkness of the esterified group decreased the μ‐opioid receptor affinity but increased the δ‐affinity. Presently, we extended our studies to investigate the antinociceptive potencies of these esterified analogues given intrathecally in the mouse tail‐flick test. Also, the specific opioid receptor antagonists and antibodies against endogenous opioid peptides were used to determine whether there are any differential mechanisms on the antinociception produced by these analogues.MethodsAntinociception was assessed using the 50 °C hot water tail‐flick test. The drugs and antibodies were administered intrathecally.ResultsThe ED50 value of analogue 1 was 1.34 nmol, exhibiting the highest analgesic effect. In contrast, the antinociceptive potency of analogue 2 was about twofold less potent than that of EM‐2. The antinociception induced by analogues 1 and 2 was mediated by the stimulation of μ‐opioid receptor in the spinal cord. However, the analogue 1‐induced antinociception also contained an additional component that was mediated by the release of dynorphin A acting on κ‐opioid receptor, which was similar to its parent EM‐2. Notably, analogue 3 exhibited only slightly lower analgesia relative to EM‐2, which may possibly be due to a direct stimulation of both μ‐ and δ‐opioid receptors.ConclusionsOur results demonstrated that EM‐2 and its analogues 1–3 produced differential antinociceptive effects when administered intrathecally. We concluded that C‐terminal amide to esterification conversion changed the antinociceptive potencies and properties of EM‐2.
Laser perforated accordion nerve conduit of poly(lactide‐co‐glycolide‐co‐ɛ‐caprolactone)
Authors: Fukuda Yutaka , Wang Wei , Ichinose Shizuko , Katakura Hiroshi , Mukai Tomokazu , Takakuda Kazuo 
Published: February 2014

AbstractAccordion nerve conduit of poly(lactide‐co‐glycolide‐co‐ε‐caprolactone) with perforations was developed by excimer laser processing. We evaluated its in vivo function for nerve repairing and discussed the influence of pore size and density. It was found that perforations help inner nerve regeneration remarkably, which effect is unrelated to pore size or density, and is not parallel with revascularization increment. Inducing of permeability only to allow substance exchange but not vessel ingrowth could facilitate nerve regeneration too. Perforating micropores with the size of 100 μm and the density of 25/cm provides permeability and vessel ingrowth both, therefore promotes the axon extension the best, larger, and more pores do not advance axon regeneration more. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 674–680, 2014.