bluuebunny/crossref_metadata_2025 huggingface dataset:
Passive separation control of a NACA0012 airfoil via a flexible flap
Authors: Fang Zhe , Gong Chunlin , Revell Alistair , Chen Gang , Harwood Adrian , O’Connor Joseph
Published: October 2019

The incorporation of nature-inspired techniques to control or reduce boundary layer separation, to bring about performance enhancements on air/water vehicles, has been an active research area for many years. In this paper, a baseline NACA0012 airfoil is modified using a short flap on its upper surface at a Reynolds number of Re = 1000. The impact of the flap configuration—described by length, attachment position, deployment angle, and material properties, on the aerodynamic performance of the airfoil—quantified by mean and fluctuating forces, is investigated, and the flow field is analyzed. Inspired by the observation of pop-up feathers on a bird’s wing, the flap is first set to be rigid for a range of location, size, and inclination angles. After the optimal location of a rigid flap has been established, the flap is then allowed to be flexible, its motion is coupled to the encircling flow field, and it is tested for a range of mass ratios and bending stiffness values. The fluid motion is obtained by solving the lattice Boltzmann equation, while the dynamics of the flexible flap are calculated using the finite element method and the coupling between the flow and flap handled by the immersed boundary method. For the flexible flap, two flapping patterns are observed and the mechanism of separation control via rigid/flexible flap is explained. Compared to the flapless NACA0012 airfoil case, in the case with a flap of optimal configuration, the mean lift coefficient is improved by 13.51%, the mean drag coefficient is decreased by 3.67%, the mean lift-drag ratio is improved by 17.84%, the maximum lift fluctuation is decreased by 40.90%, and the maximum drag fluctuation is decreased by 56.90%.
Design of a flexure-based mechanism possessing low stiffness and constant force
Authors: Tian Yanling , Zhou Chongkai , Wang Fujun , Lu Kangkang , Yuan Yanjie , Yang Mingxuan , Zhang Dawei
Published: October 2019

This paper presents a novel design of a flexure-based constant force mechanism with a long travel stroke. Unlike the conventional force control method using a force sensor and feedback controller to obtain constant force output, the proposed compliant mechanism provides a constant force utilizing the unique mechanical property of the mechanical structure. The constant force is generated by using the combination of a negative-stiffness and a positive-stiffness mechanism. In order to achieve a low driving force, the negative stiffness is realized by a special bistable beam, which is a step beam with structural holes. Meanwhile, the positive stiffness is generated by the leaf flexure hinges with structural holes. The regular structural holes can reduce the mass and stiffness of the whole mechanism. Furthermore, the elliptic integral method and the pseudo-rigid-body approach are utilized to establish the model of the constant force mechanism. Based on the established model, the performance of the constant force mechanism is evaluated computationally. Additionally, the parametric model of the proposed mechanism is investigated using the nonlinear finite element analysis. Finally, a prototype is fabricated using 3D printing technique. The open-loop and the closed-loop experimental tests are implemented to investigate the performance of the developed constant force mechanism. It is noted that the constant force mechanism can be robustly controlled by a proportional-integral-derivative control method. Experimental results demonstrate that the developed constant force mechanism has a constant force with slight fluctuation with a range of 500 μm.
A new kind of atlas of zeolite building blocks
Authors: Helfrecht Benjamin A. , Semino Rocio , Pireddu Giovanni , Auerbach Scott M. , Ceriotti Michele
Published: October 2019

We have analyzed structural motifs in the Deem database of hypothetical zeolites to investigate whether the structural diversity found in this database can be well-represented by classical descriptors, such as distances, angles, and ring sizes, or whether a more general representation of the atomic structure, furnished by the smooth overlap of atomic position (SOAP) method, is required to capture accurately structure–property relations. We assessed the quality of each descriptor by machine-learning the molar energy and volume for each hypothetical framework in the dataset. We have found that a SOAP representation with a cutoff length of 6 Å, which goes beyond near-neighbor tetrahedra, best describes the structural diversity in the Deem database by capturing relevant interatomic correlations. Kernel principal component analysis shows that SOAP maintains its superior performance even when reducing its dimensionality to those of the classical descriptors and that the first three kernel principal components capture the main variability in the dataset, allowing a 3D point cloud visualization of local environments in the Deem database. This “cloud atlas” of local environments was found to show good correlations with the contribution of a given motif to the density and stability of its parent framework. Local volume and energy maps constructed from the SOAP/machine learning analyses provide new images of zeolites that reveal smooth variations of local volumes and energies across a given framework and correlations between the contributions to volume and energy associated with each atom-centered environment.
Improvement of the electrical performance of Au/Ti/HfO2/Ge0.9Sn0.1 p-MOS capacitors by using interfacial layers
Authors: Haffner T. , Mahjoub M. A. , Labau S. , Aubin J. , Hartmann J. M. , Ghibaudo G. , David S. , Pelissier B. , Bassani F. , Salem B.
Published: October 2019

The impact of different interfacial layers (ILs) on the electrical performances of Au/Ti/HfO2/Ge0.9Sn0.1 metal oxide semiconductor (MOS) capacitors is studied. Parallel angle resolved x-ray photoelectron spectroscopy measurements show that germanium diffuses into the HfO2 layer when no IL is used. This results in an increase in the tin content at the interface and a high interface state density. We demonstrate that the use of an IL prevents germanium and HfO2 intermixing and improves the electrical performance of MOS capacitors. Several ILs are studied such as alumina (Al2O3) and plasma oxidized GeSn (GeSnOx) prior to HfO2 deposition. C–V measurements correlated with simulations made by a customized analytical model indicate an interface state density of 5 × 1011 eV−1 cm−2 for the HfO2/GeSnOx/Ge0.9Sn0.1 gate stack. This result is promising for the integration of high mobility GeSn channels in CMOS devices.
Strain in InP/ZnSe, S core/shell quantum dots from lattice mismatch and shell thickness—Material stiffness influence
Authors: Rafipoor Mona , Tornatzky Hans , Dupont Dorian , Maultzsch Janina , Tessier Mickael D. , Hens Zeger , Lange Holger
Published: October 2019

We investigate the buildup of strain in InP quantum dots with the addition of shells of the lower-lattice constant materials ZnSe and ZnS by Raman spectroscopy. Both materials induce compressive strain in the core, which increases with increasing shell volume. We observe a difference in the shell behavior between the two materials: the thickness-dependence points toward an influence of the material stiffness. ZnS has a larger Young’s modulus and requires less material to develop stress on the InP lattice at the interface, while ZnSe requires several layers to form a stress-inducing lattice at the interface. This hints at the material stiffness being an additional parameter of relevance for designing strained core/shell quantum dots.
Highly sensitive hydrogen detection using curvature change of wireless-electrodeless quartz resonators
Authors: Zhou L. , Nakamura N. , Nagakubo A. , Ogi H.
Published: October 2019

We propose a hydrogen detection method using a thin quartz resonator with a palladium thin film on its single side, which absorbs hydrogen, resulting in the film expansion and geometry change of the resonator, shifting the resonant frequency. Because the resonator is driven in a wireless manner, the other resonator side can remain electrodeless, enhancing the geometry change and then the detection sensitivity. The detection limit is 1 ppm or less. We also investigate the reaction kinetics between palladium and hydrogen through the temperature dependence of the reaction velocity constant, yielding the activation energy of 0.372 ± 0.003 eV. This is close to the activation energy for the hydrogen-atom transition from the surface to subsurface states, indicating that the adsorption reaction is dominated by the transition rather than the bulk diffusion in palladium.
Palladium oxidation leads to methane combustion activity: Effects of particle size and alloying with platinum
Authors: Goodman Emmett D. , Ye Angela A. , Aitbekova Aisulu , Mueller Oliver , Riscoe Andrew R. , Nguyen Taylor Temy , Hoffman Adam S. , Boubnov Alexey , Bustillo Karen C. , Nachtegaal Maarten , Bare Simon R. , Cargnello Matteo
Published: October 2019

Pd- and Pt-based catalysts are highly studied materials due to their widespread use in emissions control catalysis. However, claims continue to vary regarding the active phase and oxidation state of the metals. Different conclusions have likely been reached due to the heterogeneous nature of such materials containing various metal nanoparticle sizes and compositions, which may each possess unique redox features. In this work, using uniform nanocrystal catalysts, we study the effect of particle size and alloying on redox properties of Pd-based catalysts and show their contribution to methane combustion activity using operando quick extended x-ray absorption fine structure measurements. Results demonstrate that for all studied Pd sizes (3 nm–16 nm), Pd oxidation directly precedes CH4 combustion to CO2, suggesting Pd oxidation as a prerequisite step to methane combustion, and an oxidation pretreatment shows equal or better catalysis than a reduction pretreatment. Results are then extended to uniform alloyed PtxPd1−x nanoparticles, where oxidative pretreatments are shown to enhance low-temperature combustion. In these uniform alloys, we observe a composition-dependent effect with Pt-rich alloys showing the maximum difference between oxidative and reductive pretreatments. In Pt-rich alloys, we initially observe that the presence of Pt maintains Pd in a lower-activity reduced state. However, with time on stream, PdO eventually segregates under oxidizing combustion conditions, leading to a slowly increasing activity. Overall, across particle sizes and alloy compositions, we relate increased catalytic activity to Pd oxidation, thus shedding light on previous contrasting results related to the methane combustion activity of these catalysts.
Spatial distribution and substrate preferences of the non-indigenous amphipod Gammarus roeselii Gervais, 1835
Authors: Paganelli Daniele , Pandolfi Alessandra , Sconfietti Renato , Marchini Agnese
Published: October 2019

Gammarus roeselii is one of the successful non-indigenous species recently established in the Ticino River basin (Northern Italy). G. roeselii is not usually considered to be a real threat to native gammarids because no evidence has been reported so far on its effects on biodiversity and habitats. In this study, we assessed the spatial distribution of G. roeselii in the secondary hydrographic system of the southern part of the sub-lacustrine Ticino River basin and examined substrate preferences on the basis of laboratory experiments. We found that G. roeselii is well established in this area, occurring in almost all the seminatural streams, reaching high densities. Furthermore, we found that this species has a preference for two distinct types of substrate: empty shells of the bivalve Corbicula fluminea, which provide a suitable shelter for the introduced amphipod, and aquatic plants, which provide food resources. Conversely, preference for inorganic substrates, such as stones, was lower. In addition, the results indicate that G. roeselii easily inhabits the water column. The high adaptability of G. roeselii, combined with its capacity to exploit different niches and its swimming ability, are ecological characteristics that can favour its colonisation of new areas.
Morphokinetics of early equine embryo development in vitro using time-lapse imaging, and use in selecting blastocysts for transfer
Authors: Lewis Niamh , Schnauffer Karen , Hinrichs Katrin , Morganti Monica , Troup Stephen , Argo Caroline
Published: October 2019

The use of time-lapse imaging (TLI) in the evaluation of morphokinetics associated with invitro developmental competence is well described for human, cattle and pig embryos. It is generally accepted that embryos that complete early cleavage sooner are more likely to form blastocysts and that timing of later events, such as blastocyst formation and expansion, are predictive of implantation potential and euploid status. In the horse, morphokinetics as a predictor of developmental competence has received little attention. In this study we evaluated the morphokinetics of early equine embryo development invitro for 144 oocytes after intracytoplasmic sperm injection and report the timings of blastocyst development associated with ongoing pregnancy for the first time. There was a tendency for time of cytoplasmic extrusion and first cleavage to occur earlier in the embryos that went on to form blastocysts (n=19) compared with those that arrested, and for first cleavage to occur earlier in blastocysts that established pregnancies that were ongoing (n=4) compared with pregnancies that were lost (n=2). TLI was clinically useful in identifying blastocysts when evaluation of morphology on static imaging was equivocal.
Association of equine oocyte and cleavage stage embryo morphology with maternal age and pregnancy after intracytoplasmic sperm injection
Authors: Frank Bethany L. , Doddman Courtney D. , Stokes JoAnne E. , Carnevale Elaine M.
Published: October 2019

In this retrospective study the morphological characteristics of oocytes and cleavage stage embryos were associated with pregnancy results from clinical intracytoplasmic sperm injection (ICSI) in mares. Oocytes were collected from preovulatory follicles, and images (×200; n=401) were captured for measurements of ooplasm, the perivitelline space and zona pellucida. After ICSI and before transfer into recipients’ oviducts, cleavage stage embryos were imaged (n=178). Oocyte donor ages (3–13, 14–19, 20–23, 24–27 years) were compared, as were mares aged 3–13 years without versus with recent histories of performance or injury stress. Cleavage rates did not differ with age. However, pregnancy rates declined and pregnancy loss rates (11–50 days gestation) increased with mare age. Young mares with performance or injury stress had significantly lower pregnancy rates than young mares under management typical for broodmares. No morphological oocyte characteristic was consistently associated with age or pregnancy outcome. Cleavage stage embryo morphology was not associated with pregnancy outcome; however, the rate of embryo development before oviductal embryo transfer was faster (P<0.05) for embryos that resulted in an early pregnancy (≤17 days) and tended (P ≤ 0.1) to be higher for embryos that produced a 50-day pregnancy. Embryonic vesicles that had a more rapid increase in diameter were more often (P<0.05) maintained until 50 days gestation.
Mutations in thyroid hormone receptor α1 cause premature neurogenesis and progenitor cell depletion in human cortical development
Authors: Krieger Teresa G. , Moran Carla M. , Frangini Alberto , Visser W. Edward , Schoenmakers Erik , Muntoni Francesco , Clark Chris A. , Gadian David , Chong Wui K. , Kuczynski Adam , Dattani Mehul , Lyons Greta , Efthymiadou Alexandra , Vargha-Khadem Faraneh , Simons Benjamin D. , Chatterjee Krishna , Livesey Frederick J.
Published: October 2019

Significance

Thyroid hormone deficiencies are the most common preventable causes of intellectual disability. We report that mutations in the thyroid hormone receptor α1 gene (
THRA
) that result in intellectual disability also reduce brain size. Using human
THRA
mutation stem cell models, we studied the impact of
THRA
mutations on human brain development by combining quantitative lineage analysis, gene expression analyses, and novel assays of neuroepithelium formation. We found that
THRA
regulates the balance between progenitor self-renewal and neurogenesis, and thus overall brain size. Importantly, these in vitro results are consistent with in vivo evidence from magnetic resonance imaging of people with these mutations, advancing our understanding of thyroid hormone action in human brain development.
Physiological changes during first encounters and their role in determining the perceived interaction quality
Authors: Rudnicki Konrad , Declerck Carolyn , De Backer Charlotte , Berth Mario
Published: October 2019

What determines if the first interaction between strangers will be a pleasant experience? We conducted an experiment to investigate the extent to which the perceived quality of an interaction is influenced by conversation content and context, and we document the physiological changes that are likely to play a role in establishing rapport. Females who did not know each other met in pairs and conducted a gossip- or creativity task, either face-to-face or online. The conversation content had no effect on the quality of online interactions. However in the face-to-face condition gossip was associated with better interaction quality. Tonic electrodermal activity steadily declined throughout the interaction, while phasic electrodermal activity first peaked and then returned to baseline. Neither were related to perceived interaction quality. Heart rate variability (HRV) dropped at first but then remained stable. A smaller drop in HRV drop corresponded to higher ratings of rapport and liking. Together these results suggest that gossip can improve the quality of a face-to-face interaction between strangers, and support the conjecture that parasympathetic activity is a marker of human openness to social engagement.
Histone methyltransferase Nsd2 is required for follicular helper T cell differentiation
Authors: Long Xuehui , Zhang Le , Zhang Yang , Min Min , Lin Bichun , Chen Jingjing , Ma Xiaojie , Zhai Sulan , Cai Zhenming , Liu Yingxia , Lu Yanlai , Che Nan , Tan Wenfeng , Qin Jun , Wang Xiaoming
Published: October 2019

Follicular helper T (Tfh) cells provide essential help for humoral immune response. Transcriptional factor Bcl6 is the master regulator for Tfh generation and is induced very early after T cell activation in a CD28-dependent manner, but how CD28 signal promotes Bcl6 early expression remains unknown. Here we found that CD28 signal quickly induces expression of the H3K36me2 methytransferase Nsd2, which is required for Bcl6 expression as early as the first cell division after T cell activation. Nsd2 deficiency in T cells leads to decreased Bcl6 expression, impaired Tfh generation, compromised germinal center response, and delayed virus clearance. Ectopic Bcl6 expression rescues the Tfh defect of Nsd2 KO cells. ICOS signal is dispensable for early Nsd2 induction but required for sustained Nsd2 expression, which is critical for Tfh maintenance. Overexpression of Nsd2 increases Bcl6 expression and enhances Tfh generation; 4-mo-old mice even develop spontaneous Tfh. Overall, our study reveals Nsd2 as a critical epigenetic regulator for Tfh differentiation.
Morphology of wetting-layer states in a simple quantum-dot wetting-layer model
Authors: Eichelmann Marcel , Wiersig Jan
Published: October 2019

The excitation of semiconductor quantum dots often involves an attached wetting layer with delocalized single-particle energy eigenstates. These wetting-layer states are usually approximated by (orthogonalized) plane waves. We show that this approach is too crude. Even for a simple model based on the effective-mass approximation and containing one or a few lens-shaped quantum dots on a rectangular wetting layer, the wetting-layer states typically show a substantially irregular and complex morphology. To quantify this complexity we use concepts from the field of quantum chaos such as spectral analysis of energy levels, amplitude distributions, and localization of energy eigenstates.
Designing functional ferroelectric interfaces from first-principles: dipoles and band bending at oxide heterojunctions
Authors: Dorin Rusu , Filip Lucian Dragos , Pintilie Lucian , Butler Keith Tobias , Plugaru Neculai
Published: October 2019

The fundamental phenomena at ferroelectric interfaces have been the subject of thorough theoretical and computational studies due to their usefulness in a large variety of emergent electronic devices, solar cells and catalysts. Ferroelectricity determines interface band-bending and shifts in electron energies, which can be beneficial or detrimental to device performance. However, the underlying mechanisms are still the subject of debate and investigation, as a deeper understanding of the electrochemistry is required to develop bona fide design principles for functional ferroelectric surfaces and interfaces. Here, using first principles calculations within the GGA + U formalism, we investigate the problem of band alignment in non-defective, asymmetric SrRuO3/PbTiO3/SrRuO3 capacitors with ultra-thin ferroelectric layers. The effects of the dielectric size on the polar distortion stability and interface-specific properties are analyzed. It is shown that the critical size of the dielectric for polarization switching is

≈
2

nm

(5 PbTiO3 u.c.). Below this limit there is no bulk-like region in the dielectric, the space charge accumulated at interfaces leads to the presence of gap states in the whole PbTiO3 layer and ferroelectricity vanishes. We draw the band alignment diagrams as given by the band line-up and band structure terms, as well as by taking Ti 3s semi-core states as reference. In the ferroelectric structures, both approaches predict a strong effect of band-bending on the type of contact, Schottky or Ohmic, at the asymmetric interfaces. The effect of interface states on the interface dipole amplitude and band alignment is discussed.
Measuring the temperature and heating rate of a single ion by imaging
Authors: Srivathsan Bharath , Fischer Martin , Alber Lucas , Weber Markus , Sondermann Markus , Leuchs Gerd
Published: October 2019

We present a technique based on high resolution imaging to measure the absolute temperature and the heating rate of a single ion trapped at the focus of a deep parabolic mirror. We collect the fluorescence light scattered by the ion during laser cooling and image it onto a camera. Accounting for the size of the point-spread function and the magnification of the imaging system, we determine the spatial extent of the ion, from which we infer the mean phonon occupation number in the trap. Repeating such measurements and varying the power or the detuning of the cooling laser, we determine the heating rate induced by any kind of effect other than photon scattering. In contrast to other established schemes for measuring the heating rate, the ion is always maintained in a state of thermal equilibrium at temperatures close to the Doppler limit.
Double-slit interferometry as a lossy beam splitter
Authors: Sadana Simanraj , Sanders Barry C , Sinha Urbasi
Published: October 2019

We cast diffraction-based interferometry in the framework of post-selected unitary description towards enabling it as a platform for quantum information processing (QIP). We express slit-diffraction as an infinite-dimensional transformation and truncate it to a finite-dimensional transfer matrix by post-selecting modes. Using such a framework with classical fields we show that a customized double-slit setup is effectively a lossy beam splitter in a post-selected sense. Diffraction optics provides a robust alternative to conventional multi-beam interferometry with scope for miniaturization, and also has applications in matter wave interferometry. In this work, the classical treatment of slit-diffraction sets the stage for quantization of fields and implementing higher-dimensional QIP like that done with other platforms such as orbital angular momentum.
Finite-dimensional pair coherent state engendered via the nonlinear Bose operator realization and its Wigner phase-space distributions
Authors: Liu Jianming , Meng Xiangguo
Published: October 2019

We theoretically analyze the photon number distribution, entanglement entropy, and Wigner phase-space distribution, considering the finite-dimensional pair coherent state (FDPCS) generated in the nonlinear Bose operator realization. Our results show that the photon number distribution is governed by the two-mode photon number sum q of the FDPCS, the entanglement of the FDPCS always increases quickly at first and then decreases slowly for any q, and the nonclassicality of the FDPCS for odd q is more stronger than that for even q.
Shock-induced migration of asymmetry tilt grain boundary in iron bicrystal: A case study of Σ3 [110]*
Authors: Zhang Xueyang , Wang Kun , Chen Jun , Hu Wangyu , Zhu Wenjun , Xiao Shifang , Deng Huiqiu , Cai Mengqiu
Published: October 2019

Many of our previous studies have discussed the shock response of symmetrical grain boundaries in iron bicrystals. In this paper, the molecular dynamics simulation of an iron bicrystal containing Σ3 [110] asymmetry tilt grain boundary (ATGB) under shock-loading is performed. We find that the shock response of asymmetric grain boundaries is quite different from that of symmetric grain boundaries. Especially, our simulation proves that shock can induce migration of asymmetric grain boundary in iron. We also find that the shape and local structure of grain boundary (GB) would not be changed during shock-induced migration of Σ3 [110] ATGB, while the phase transformation near the GB could affect migration of GB. The most important discovery is that the shock-induced shear stress difference between two sides of GB is the key factor leading to GB migration. Our simulation involves a variety of piston velocities, and the migration of GB seems to be less sensitive to the piston velocity. Finally, the kinetics of GB migration at lattice level is discussed. Our work firstly reports the simulation of shock-induced grain boundary migration in iron. It is of great significance to the theory of GB migration and material engineering.
ν’s in Particle Physics and Cosmology
Authors: Nasri Salah
Published: October 2019

We propose a minimal scale-invariant (SI) scotogenic model and study its phenomenological implications. The SI scotogenic predicts a singlet scalar (dilaton) that triggers electroweak symmetry breaking and sources the lepton number violation that allows radiative neutrino mass. A viable parameter space is found for dark matter candidate and the observed neutrino oscillation. The model can be probed in lepton flavor violating processes, future dark matter direct detection experiments, and collider searches.
B − L violating interactions in supersymmetric SO(10) models
Authors: Nath Pran , Syed Raza M
Published: October 2019

An analysis is given of B − L violating interactions in SO(10) arising from the integration of

10
+

10

¯

of SU(5) of heavy Higgs. The analysis is done within the well defined missing partner model where the doublet-triplet splitting arises naturally. The Higgs representations of the model consist of two 10-plets, one 120, one 210 plet and a

126
+

126

¯

representations of SO(10). The SO(10) symmetry is spontaneously broken by the singlet in the

126
+

126

¯

and 210. In this work we focus on the B−L interactions arising from the elimination of

10
+

10

¯

plets of SU(5). We compute five field and six field B−L violating operators. The analysis extends previous analyses where B−L violating interactions arising from the elimination of

5
+

5
¯

and

45
+

45

¯

were computed. Specifically we compute dimension 6, 7 and 9 operators. These interactions can generate GUT scale baryogengesis, proton decay, and

n
−

n
¯

oscillations.
(2+1) dimensional cosmological models in f(R, T) gravity with (R, T)
Authors: Islam Safiqul , Kumar Praveen , Khadekar G.S. , Das Tapas K
Published: October 2019

We intend to study a new class of cosmological models in f(R, T) modified theories of gravity, hence define the cosmological constant as a function of the trace of the stress energy-momentum-tensor T and the Ricci scalar R, and name such a model Λ(R, T) gravity where we have specified a certain form of Λ(R, T). Λ(R, T) is also defined in the perfect fluid and dust case. Some physical and geometric properties of the model are also discussed. The pressure, density and energy conditions are studied both when Λ is a positive constant and when Λ = Λ(t), i.e a function of cosmological time, t. We study behavior of some cosmological quantities such as Hubble and deceleration parameters. The model is innovative in the sense that it has been described in terms of both R and T and display better understanding of the cosmological observations.
Theoretical electronic structure with rovibrational and dipole moment calculation of the SiS Molecule
Authors: El Kasty Hind , Zeid Israa , El-Kork Nayla , Korek Mahmoud
Published: October 2019

The quantitative distribution of the molecular abundances in the universe is a classical problem in astronomy, astrophysics and cosmo-chemistry. Astrophysicists are interested in determining the abundances of molecular species in order to: (1) Know the primordial composition of the solar system, and its relation to the past and present composition of the earth. (2) Have a complete understanding of physical and chemical processes taking place in the stellar atmospheres and the interstellar medium (3) Test the hypotheses that have been proposed for element formation. To investigate the presence of astronomical sources, experimental astrophysicists usually study the wavelength and intensity of light that they emit. Many diatomic molecular species are present in various astrophysical sources, however, the theoretical studies on such species are not enough and information is missing in that area. Knowledge of the electronic structure, Franck-Condon factors (FCFs), and other related quantities for a band system of a diatomic molecule is essential to arrive at its astrophysically significant parameters such as kinetics of the energy transfer, radiative lifetimes, band intensity, vibrational temperature, etc. In this view, the spectroscopic and ro-vibrational constants, FCFs of several electronic states of the diatomic molecule SiS electronic have been evaluated in this work. We performed theoretical calculation of the low-lying electronic state, of the molecule SiS by using the Complete Active Space Self Consistent Field (CASSCF) method followed by the Multi Reference Configuration Interaction with Davidson correction MRCI+Q. The potential energy along with the dipole moment curves of these states have been calculated along with the spectroscopic constants Re, ωe, Be, and Te. Additionally, the Rotation-vibration lines for the considered electronic states were obtained by direct solution of the nuclear motion Schrödinger equation using the canonical approach with program Rovib-1
Increased deep soil respiration detected despite reduced overall respiration in permafrost peat plateaus following wildfire
Authors: Gibson Carolyn M , Estop-Aragonés Cristian , Flannigan Mike , Thompson Dan K , Olefeldt David
Published: October 2019

Wildfire in boreal permafrost peatlands causes a thickening and warming of the seasonally thawed active layer, exposing large amounts of soil carbon to microbial processes and potential release as greenhouse gases. In this study, conducted in the discontinuous permafrost zone of western Canada, we monitored soil thermal regime and soil respiration throughout the 2016 growing season at an unburned peat plateau and two nearby peat plateaus that burned 16 and 9 years prior to the study. Maximum seasonal soil temperature at 40 cm depth was 4 °C warmer in the burned sites, and active layers were ∼90 cm thicker compared to the unburned site. Despite the deeper and warmer seasonally thawed active layer, we found higher soil respiration in the unburned site during the first half of the growing season. We partitioned soil respiration into contribution from shallow and deep peat using a model driven by soil temperatures at 10 and 40 cm depths. Cumulative estimated deep soil respiration throughout the growing season was four times greater in the burned sites than in the unburned site, 32 and 8 g C m−2 respectively. Concurrently, cumulative shallow soil respiration was estimated to be lower in the burned than unburned site, 49 and 80 g C m−2 respectively, likely due to the removal of the microbially labile soil carbon in the shallow peat. Differences in deep contribution to soil respiration were supported by radiocarbon analysis in fall. With effects of wildfire on soil thermal regime lasting for up to 25 years in these ecosystems, we conclude that increased loss of deep, old, soil carbon during this period is of similar magnitude as the direct carbon losses from combustion during wildfire and thus needs to be considered when assessing overall impact of wildfire on carbon cycling in permafrost peatlands.
Terahertz continuum generation in the LCS (Lieb) lattice
Authors: Jin Qiutong , Andersen David R
Published: October 2019

Rabi oscillations in two-level Dirac systems have been shown to alter the frequency content of the system’s nonlinear response. In particular, when considering Rabi oscillations in a quantum model beyond the semiclassical Boltzmann theory, even harmonics may be generated despite the centrosymmetric nature of these systems. This effect magnifies with increasing excitation intensity. In this work, we extend the Rabi theory to a three-level Dirac system arising from a line-centered-square optical lattice. In this case, the Dirac cones are bisected at the Dirac point by a flat band that persists throughout the Brillioun zone. Due to the presence of this flat band, we expect a significant enhancement of the coupling between Dirac states, resulting in a large increase of the Rabi effects and the associated nonlinearities, leading to continuum generation of terahertz radiation.
Optimism and Pain Interference in Aging Women
Authors: Judge Stephanie T , Clasey Jody L , Crofford Leslie J , Segerstrom Suzanne C
Published: October 2019

Background

Pain interferes with people’s daily lives and often limits the extent to which they can pursue goals and engage in activities that promote well-being. However, people vary in how much interference they experience at a given level of pain.

Purpose

The present study tested how optimism affects and is affected by pain interference and goal-directed activity among older women.

Methods

Every 3 months for 2 years, community-dwelling middle- and older-age women (N = 199) completed online daily diaries at home for a 7 day period, in which they reported their daily pain, pain interference, and goal-directed activity. Optimism was measured at the start and end of the study. Multilevel models tested the between- and within-person relationships among pain, optimism, and pain interference or goal-directed activity. Linear regression predicted change in optimism over 2 years from pain interference and goal-directed activity.

Results

Pain best predicted pain interference and optimism best predicted goal-directed activity. There were subtle interactions between optimism and pain-predicting interference and goal-directed activity. Accumulated goal-directed activity and pain interference across the study predicted longitudinal changes in optimism, with higher activity and lower pain interference predicting increased optimism over 2 years.

Conclusions

Optimism may play a protective role in disruptions caused by pain on a day-to-day basis, leading to increased goal-directed activity and possibly decreased pain interference. In turn, less interference and more goal-directed activity feed forward into increased optimism, resulting in a virtuous cycle that enhances optimism and well-being among older women.
Photosynthesis: basics, history and modelling
Authors: Stirbet Alexandrina , Lazár Dušan , Guo Ya , Govindjee Govindjee
Published: October 2019

Background

With limited agricultural land and increasing human population, it is essential to enhance overall photosynthesis and thus productivity. Oxygenic photosynthesis begins with light absorption, followed by excitation energy transfer to the reaction centres, primary photochemistry, electron and proton transport, NADPH and ATP synthesis, and then CO2 fixation (Calvin–Benson cycle, as well as Hatch–Slack cycle). Here we cover some of the discoveries related to this process, such as the existence of two light reactions and two photosystems connected by an electron transport ‘chain’ (the Z-scheme), chemiosmotic hypothesis for ATP synthesis, water oxidation clock for oxygen evolution, steps for carbon fixation, and finally the diverse mechanisms of regulatory processes, such as ‘state transitions’ and ‘non-photochemical quenching’ of the excited state of chlorophyll a.

Scope

In this review, we emphasize that mathematical modelling is a highly valuable tool in understanding and making predictions regarding photosynthesis. Different mathematical models have been used to examine current theories on diverse photosynthetic processes; these have been validated through simulation(s) of available experimental data, such as chlorophyll a fluorescence induction, measured with fluorometers using continuous (or modulated) exciting light, and absorbance changes at 820 nm (ΔA820) related to redox changes in P700, the reaction centre of photosystem I.

Conclusions

We highlight here the important role of modelling in deciphering and untangling complex photosynthesis processes taking place simultaneously, as well as in predicting possible ways to obtain higher biomass and productivity in plants, algae and cyanobacteria.
Plasma membrane receptor-like kinases and transporters are associated with 2,4-D resistance in wild radish
Authors: Goggin Danica E , Bringans Scott , Ito Jason , Powles Stephen B
Published: October 2019

Background and Aims

Resistance to the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) in wild radish (Raphanus raphanistrum) appears to be due to a complex, multifaceted mechanism possibly involving enhanced constitutive plant defence and alterations in auxin signalling. Based on a previous gene expression analysis highlighting the plasma membrane as being important for 2,4-D resistance, this study aimed to identify the components of the leaf plasma membrane proteome that contribute to resistance.

Methods

Isobaric tagging of peptides was used to compare the plasma membrane proteomes of a 2,4-D-susceptible and a 2,4-D-resistant wild radish population under control and 2,4-D-treated conditions. Eight differentially abundant proteins were then targeted for quantification in the plasma membranes of 13 wild radish populations (two susceptible, 11 resistant) using multiple reaction monitoring.

Key Results

Two receptor-like kinases of unknown function (L-type lectin domain-containing receptor kinase IV.1-like and At1g51820-like) and the ATP-binding cassette transporter ABCB19, an auxin efflux transporter, were identified as being associated with auxinic herbicide resistance. The variability between wild radish populations suggests that the relative contributions of these candidates are different in the different populations.

Conclusions

To date, no receptor-like kinases have been reported to play a role in 2,4-D resistance. The lectin-domain-containing kinase may be involved in perception of 2,4-D at the plasma membrane, but its ability to bind 2,4-D and the identity of its signalling partner(s) need to be confirmed experimentally. ABCB19 is known to export auxinic compounds, but its role in 2,4-D resistance in wild radish appears to be relatively minor.
Nectar as manipulator: how nectar traits influence changes in pollinator groups of Aechmea vanhoutteana, a bromeliad from the Brazilian Atlantic Forest
Authors: Zambon Vivian , Agostini Kayna , Nepi Massimo , Rossi Mônica Lanzoni , Martinelli Adriana Pinheiro , Sazima Marlies
Published: October 2019

Nectar is an important floral resource in the establishment of plant-pollinator interactions. Recent studies have shown that nectariferous tissues are independent of the ABC model of floral development and that ecological interactions can modify their expression. In this sense, it would be interesting to study generalist species in relation to nectar production and nectary morpho-anatomy to verify the strategies used to attract different pollinator groups. We recorded nectar production dynamics in Aechmea vanhoutteana (Bromeliaceae) from a morpho-functional and ultrastructural perspective. We observed different species of hummingbirds, bees and butterflies visiting flowers of A.vanhoutteana, and their frequency varied throughout floral anthesis. The nectar volume and quantity of sugar also varied significantly during anthesis, and this spatial and temporal variability seems to be related to an increase in bee visits, representing an important aspect of the reproductive strategy of this species, since bees can fly longer distances than the observed hummingbirds (although both have territorial behaviours). Thus, it can be suggested that anatomical and physiological nectar traits may be related to pollen flow, an important aspect of the reproductive strategy of A. vanhoutteana, suggesting plant resource allocation for optimizing reproduction through nectar production.
Combinations of mineral and bone disorder markers and risk of death and hospitalizations in the international Dialysis Outcomes and Practice Patterns Study
Authors: Fuller Douglas S , Dluzniewski Paul J , Cooper Kerry , Bradbury Brian D , Robinson Bruce M , Tentori Francesca
Published: October 2019

Background

Prior studies have developed a chronic kidney disease–mineral and bone disorder (CKD-MBD) composite score based on combinations of calcium (Ca), phosphorus (P) and parathyroid hormone (PTH) that have been shown to be associated with an increased risk of clinical outcomes in the USA. We examined this association in a contemporary, international cohort of hemodialysis patients.

Methods

We studied 19 313 patients surviving ≥12 months in the Dialysis Outcomes and Practice Patterns Study Phases 3–5 (2005–15) from Europe, Canada and the USA. The CKD-MBD composite score was defined as the number of markers above target levels (P, 3.5–5.5 mg/dL; Ca, 8.4–10.2 mg/dL; PTH, 150–600 pg/mL). Using Cox models, we estimated hazard ratios (HRs) for death and a composite event (death or hospitalization), contrasting MBD 2/3 (2–3 parameters above target) with MBD 0 (all in target), adjusted for a disease risk score (DRS).

Results

MBD 2/3 above target was observed in 10–14% of patients across regions and was associated with greater DRS-adjusted mortality {HR 1.41 [95% confidence interval (CI) 1.10–1.82]} and composite events [HR 1.23 (95% CI 1.10–1.38)] in the USA compared with MBD 0; the mortality association was stronger for patients ≥ 65 years of age [HR 1.82 (95% CI 1.28–2.58)] compared with patients <65 years of age [HR 1.11 (95% CI 0.80–1.55)]. HRs observed in Canada and Europe were generally consistent but weaker. Estimates for MBD 2/3 outside target (above or below) were slightly lower in all regions.

Conclusions

Simultaneous consideration of Ca, P and PTH may help in identifying patients on dialysis with a higher risk of major clinical outcomes related to CKD-MBD.
The effect of climate change on the escape kinematics and performance of fishes: implications for future predator–prey interactions
Authors: Domenici Paolo , Allan Bridie J M , Lefrançois Christel , McCormick Mark I
Published: October 2019

Climate change can have a pronounced impact on the physiology and behaviour of fishes. Notably, many climate change stressors, such as global warming, hypoxia and ocean acidification (OA), have been shown to alter the kinematics of predator–prey interactions in fishes, with potential effects at ecological levels. Here, we review the main effects of each of these stressors on fish escape responses using an integrative approach that encompasses behavioural and kinematic variables. Elevated temperature was shown to affect many components of the escape response, including escape latencies, kinematics and maximum swimming performance, while the main effect of hypoxia was on escape responsiveness and directionality. OA had a negative effect on the escape response of juvenile fish by decreasing their directionality, responsiveness and locomotor performance, although some studies show no effect of acidification. The few studies that have explored the effects of multiple stressors show that temperature tends to have a stronger effect on escape performance than OA. Overall, the effects of climate change on escape responses may occur through decreased muscle performance and/or an interference with brain and sensory functions. In all of these cases, since the escape response is a behaviour directly related to survival, these effects are likely to be fundamental drivers of changes in marine communities. The overall future impact of these stressors is discussed by including their potential effects on predator attack behaviour, thereby allowing the development of potential future scenarios for predator–prey interactions.
Complementary Use of Various Types of Anthropogenic Habitats by Scolia hirta (Hymenoptera: Scoliidae) and Scolia sexmaculata
Authors: Twerd Lucyna , Sobieraj-Betlińska Anna , Banaszak Józef
Published: October 2019

Scolia hirta (Schrank) and Scolia sexmaculata (O.F. Müller) are Palearctic, parasitic Aculeata inhabiting forests and forest steppes. At present, the abundance and dispersal of these species are increasing considerably in Poland and other European countries, allowing observation of their possible habitat preferences. The analysis of the preferences of S. hirta and S. sexmaculata was conducted in Northern and North-Eastern Poland based on the evaluation of their occurrence in six types of habitats: (A) psammophilous and xerothermic grasslands, (B) old fields, (C) city outskirts, (D) sites in housing/industrial zones, (E) sand quarries, (F) post-industrial wastelands, and in a total of three types of landscape: 1) semi-natural, 2) urban, and 3) industrial. We demonstrated that the habitat most frequently colonized by S. hirta is post-industrial wastelands, while S. sexmaculata were most often sampled in old fields, with the frequency of 100% and 94.11%, respectively. At the same time, the abundance of the species in these habitats was also the highest, with a mean of 8.00 and 10.88 individuals, respectively. Moreover, S. hirta was relatively frequently found in the urban landscape (67% in city outskirts and 88.23% in the housing/industrial zones), while S. sexmaculata colonized these areas to a considerably low degree (25% in city outskirts and 29.41% in the housing/industrial zones). We also established that the occurrence of the species was affected by the forest cover in the closest vicinity of the study sites, which significantly modified the habitat preference of the species analyzed.