Large Positive Shift Research Articles

Who should handle retail? Vertical contracts, customer service, and social welfare in a Chinese mobile phone market

Using data on mobile phone handset sales from a single retail store, we examine the impact of different retail responsibility designations and vertical contracts on seller service provision, firm profitability, and social welfare. During our sample, this store switched from retailer-managed retailing with linear pricing contracts to manufacturer-managed retailing with revenue-sharing contracts. We estimate consumer demand and manufacturer cost parameters. Demand estimates indicate a large positive shift that coincided with the vertical change, consistent with improved retail customer service. Welfare estimates suggest that consumers derived substantial surplus from the improved customer service in addition to that from lowered prices.

High sensitivity surface enhanced Raman spectroscopy of R6G on in situ fabricated Au nanoparticle/graphene plasmonic substrates

Plasmonic gold nanoparticles (AuNP) with controllable dimensions have been fabricated in situ on graphene at moderately elevated temperature for high sensitivity surface enhanced Raman spectroscopy (SERS) of Rhodamine 6G (R6G) dye molecules. Significantly enhanced Raman signature of R6G dyes were observed on AuNP/graphene substrates as compared to the case without graphene with an improvement factor of 400%, which is remarkably greater than previous results obtained in ex situ fabricated SERS substrate. Simulation of localized electromagnetic field around AuNPs with and without the underneath graphene layer reveals an enhanced local electromagnetic field due to the plasmonic effect of AuNPs, while additional Ohmic loss occurs when graphene is present. The enhanced local electromagnetic field by plasmonic AuNPs is unlikely the dominant factor contributing to the observed high SERS sensitivity on R6G/AuNP/graphene substrate. Instead, the p-doped graphene, which is supported by the large positive Dirac point shift away from “zero” observed in AuNP/graphene field effect transistors, promotes SERS signals through enhanced molecule adsorption and non-resonance molecular–substrate chemical interaction.

Axial thiophenolate coordination on diiron(III)bisporphyrin: influence of heme-heme interactions on structure, function and electrochemical properties of the individual heme center.

The binding of a series of substituted thiophenols as axial ligands on a highly flexible ethane-bridged diiron(III)bisporphyrin framework has been investigated as a model of diheme proteins. Spectroscopic characterization reveals a high-spin (S = 5/2) state of iron for all of the pentacoordinate thiophenolato complexes. In the UV-visible spectra of the complexes, the positions of the Soret and band I have been found to be dependent on the pKa of thiophenols. The alternating shift pattern, which has opposite sign of the chemical shifts for meta- vs. ortho- and para-protons in the (1)H NMR spectra, is attributed to negative and positive spin densities, respectively, on thiophenolate carbon atoms and is indicative of π-spin delocalization to the bound thiophenolate ligand. The Fe(III)/Fe(II) redox couple of the complexes bears a linear relationship with the pKa of thiophenol and is found to be positively shifted with decreasing pKa. The effect of the electronic nature of the substituent on the thiophenolate ring has also been demonstrated in which a large potential range of 540 mV was observed (in contrast to the value of only 270 mV in case of monoheme analogues) for the Fe(III)/Fe(II) redox couple on going from monoheme to diheme and is attributed to the interheme interaction. Also, the Fe(III)/Fe(II) redox potential of the thiophenolato complexes has been found to be more positively shifted compared to their phenolato analogues, which was further supported by DFT calculation. The addition of another thiophenol at the sixth axial position of the five-coordinate thiophenolato complex causes a change in iron spin from high (S = 5/2) to low (S = 1/2) along with a large positive shift of 490 mV for the Fe(III)/Fe(II) redox couple.

Reflective vertical cavity quantum-well saturable absorber as an all-optical nonlinear phase-shifting element

A scheme of an all-optical nonlinear phase-shifting element is proposed, based on a reflective vertical cavity semiconductor (quantum-well) saturable absorber (R-VCSSA). The nonlinear round-trip phase shift in a low-intensity resonant VCSSA is obtained at an input intensity due to the saturating nonlinearity in index change and optically induced thermal effects. An enhanced large nonlinear positive or negative phase shift incurred in a reflected signal is investigated analytically with the wavelength tuning of the probe signal around the low-intensity resonant wavelength of a Fabry–Perot cavity. The device may be useful in compensating the phase of an input signal, either positive or negative, in long-haul fiber communications. A representative InGaAs/InP quantum-well-based VCSSA is considered to demonstrate the phase shift in the pump–probe configuration. With a device speed of 10 GHz, maximum phase shifts of −0.24 and +0.14  rad at pump power of 19.2 mW are observed for the operations at probe wavelengths of 1555.6 and 1557.8 nm, respectively.

Probing signal phase in direct visualization of short transverse relaxation time component (ViSTa).

To demonstrate the phase evolutions of direct visualization of short transverse relaxation time component (ViSTa) matches with those of myelin water. Myelin water imaging (MWI) measures short transverse signals and has been suggested as a biomarker for myelin. Recently, a new approach, ViSTa, has been proposed to acquire short T2* signals by suppressing long T1 signals. This method does not require any ill-conditioned data processing and therefore provides high-quality images. In this study, the phase of the ViSTa signal was compared with the phase of myelin water simulated by the magnetic susceptibility model of hollow cylinder. The phase evolutions of the ViSTa signal were similar to the simulated myelin water phase evolutions. When fiber orientation was perpendicular relative to the main magnetic field, both the ViSTa and the simulated myelin water phase showed large positive frequency shifts, whereas the gradient echo phase showed a slightly negative frequency shift. Additionally, the myelin water phase map generated using diffusion tensor imaging (DTI) information revealed a good match with the ViSTa phase image. The results of this study support the origin of ViSTa signal as myelin water. ViSTa phase may potentially provide sensitivity to demyelination.

Reliability of Commercially Available SiC Power Mosfets

With the introduction of SiC power MOSFETs into the commercial market place, it is critically important to determine the reliability of these devices. A number of potential issues need to be addressed, including the stability of the device threshold voltage, and the reliability of both the body diode and the gate oxide. An ideal switch has minimal leakage current in the OFF state and very low resistance in the ON state. But an excess negative shift of the threshold voltage under high-temperature reverse-bias (HTRB) conditions can lead to a critical increase in OFF-state leakage current and potential device failure [1]. In a similar fashion, a large positive shift of the threshold voltage may occur under high-temperature gate-bias (HTGB) conditions, wherein a positive bias-temperature stress is applied. This can lead to a significant increase in the ON-state resistance.This work focuses on the stability of the device threshold voltage when subject to bias-temperature stressing, although the reliability of the body diode will also be discussed in the full paper. The primary defects that contribute to shifts in the threshold voltage are near-interfacial oxide traps [2, 3]. A certain number of defect states become activated during device processing. This can vary depending on the details of the processing steps, or may be a function of device design. Typical instabilities of the threshold voltage at room temperature are about 0.25 V. Much larger threshold-voltage instabilities are observed following bias-temperature gate-bias stressing. This is very likely due to the activation of additional oxide traps, which can then participate in the oxide-trap charging process [3]. Since this activation is a function of time at temperature (and bias), more stressful processing conditions can quicken the onset of significant shifts in the threshold voltage during bias-temperature stressing. (Similarly, stressing at higher temperatures also leads to an earlier onset of significant increases in threshold-voltage instability.)As a result, we have observed a marked difference in the onset of significant increases in threshold-voltage instability between different commercial vendors. This difference in bias-temperature stress time can vary in some cases by two orders of magnitude. Detailed results will be provided in the full paper.

Stable-isotope chemostratigraphy as a tool to correlate complex Mississippian marine carbonate facies of the Anadarko shelf, Oklahoma and Kansas

The Mississippian section of the United States mid-continent Anadarko Basin (Oklahoma and Kansas) has been a prolific hydrocarbon reservoir since the 1920s, yet large-scale regional correlations between individual stratigraphic units remain difficult because of the complex and heterogeneous nature of the carbonate facies. New sedimentologic and carbon isotopic data from a nearly continuous Mississippian core (Pan American 1 Albert Severin) from the Anadarko Basin, Oklahoma (Garfield County), United States, provides insight into the potential of carbon-isotope chemostratigraphy as a correlation tool in complex stratigraphic successions for which biostratigraphic data are not available. The carbon isotopic composition () of whole-rock samples was analyzed to determine if stratigraphic trends reflect global changes in the carbon cycle. A large positive shift (+5.6‰) in the lower Tournaisian (Kinderhookian), consistent values (averaging +2.3‰) in the upper Tournaisian through middle Visean (upper Kinderhookian–Meramecian), and a negative shift (−2.3‰) in the uppermost Visean (lower Chesterian) correspond to trends in the carbon isotopic compositions ( values) from other regional data sets, including the global type section at Arrow Canyon, Nevada. Further analysis of the data reveals that isotopic compositions are not facies dependent, suggesting that marine chemistry and depositional changes in the Anadarko Basin reflect global environmental changes during the Mississippian. These inferences demonstrate the potential of the Pan American 1 Albert Severin core to be a Mississippian-type section for the Anadarko Basin, and that stable-isotope chemostratigraphy can be used as a correlation tool to better understand the subsurface in complex successions, such as the Mississippian limestone of the United States mid-continent.

Mass-occurrence of oncoids at the Cambrian Series 2–Series 3 transition: Implications for microbial resurgence following an Early Cambrian extinction

The traditional Lower–Middle Cambrian transition (Cambrian Series 2–Series 3 transition) is marked by the first major biotic extinction of the Phanerozoic Eon. This biotic crisis has been arguably linked to changes in ocean chemistry and/or marine environments but their casual relationships remain controversial. To better understand the microbial responses to paleoceanographic changes across this critical transition, we have studied the environmental conditions for mass–occurrence of oncoids in the western North China Platform. Oncoids at the Lower–Middle Cambrian transition form 1 to 3-m-thick massive beds, show spherical–subspherical morphology, and contain 8–14 light–dark cortical laminar couplets. The light laminae are thicker and contain densely intertwined filamentous cyanobacteria that have calcified sheaths and a prostrate growth pattern. The dark laminae are thinner and rich in organic matter relics, pyrite framboids, and heterotrophic bacteria. In most oncoids, cortical laminae show the same growth orientation for more than five light–dark laminar couplets, suggesting much less frequent grain overturning than generally thought. Both light and dark laminae contain well-preserved organomineralization fabrics/textures including extracellular polymeric substances (EPSs), nanoglobules, polyhedrons, and micropeloids, suggesting oncoid formation in shallow-marine environments with high alkalinity and active sulfate reduction. The presence of pyrite framboids and heterotrophic bacterial relics implies anoxic/dysoxic bottom-water conditions. Stratigraphic correlation indicates that time-equivalent oncolites and other microbialites are widespread not only in North China, but also in other Early Cambrian successions globally. The mass-occurrence of oncoids coincides with the Kalkarindji large igneous province of Australia, a prominent negative δ13C excursion (ROECE or Redlichiid–Olenellid Extinction Carbon isotope Excursion), a significant increase in 87Sr/86Sr, and a large positive shift in δ34S. The coincidence of these events suggests that the Early Cambrian biotic crisis may have been caused by an ocean anoxic event resulting from enhanced volcanic release of CO2, global warming, and increased continental weathering. Preservation of massive oncolites is likely related to decreased metazoan grazing following an Early Cambrian biotic crisis, during which archaeocyathids and many Early Cambrian trilobite taxa went to extinction. The oncoid mass-occurrence provides evidence for the resurgence of microbial life in anoxic/dysoxic marine shelf environments concomitant with the Early Cambrian extinction event.

Solid-state NMR/NQR and first-principles study of two niobium halide cluster compounds

Two hexanuclear niobium halide cluster compounds with a [Nb6X12]2+ (X=Cl, Br) diamagnetic cluster core, have been studied by a combination of experimental solid-state NMR/NQR techniques and PAW/GIPAW calculations. For niobium sites the NMR parameters were determined by using variable Bo field static broadband NMR measurements and additional NQR measurements. It was found that they possess large positive chemical shifts, contrary to majority of niobium compounds studied so far by solid-state NMR, but in accordance with chemical shifts of 95Mo nuclei in structurally related compounds containing [Mo6Br8]4+ cluster cores. Experimentally determined δiso(93Nb) values are in the range from 2400 to 3000ppm. A detailed analysis of geometrical relations between computed electric field gradient (EFG) and chemical shift (CS) tensors with respect to structural features of cluster units was carried out. These tensors on niobium sites are almost axially symmetric with parallel orientation of the largest EFG and the smallest CS principal axes (Vzz and δ33) coinciding with the molecular four-fold axis of the [Nb6X12]2+ unit. Bridging halogen sites are characterized by large asymmetry of EFG and CS tensors, the largest EFG principal axis (Vzz) is perpendicular to the X-Nb bonds, while intermediate EFG principal axis (Vyy) and the largest CS principal axis (δ11) are oriented in the radial direction with respect to the center of the cluster unit. For more symmetrical bromide compound the PAW predictions for EFG parameters are in better correspondence with the NMR/NQR measurements than in the less symmetrical chlorine compound. Theoretically predicted NMR parameters of bridging halogen sites were checked by 79/81Br NQR and 35Cl solid-state NMR measurements.

Structural Basis of Lipid-Driven Conformational Changes in the Hyperpolarization-Activated Potassium Channel MVP

DOTAP is a bilayer-forming lipid containing a positively charged trimethyl-ammonium group instead of a negatively charged phosphodiester. When reconstituted in pure DOTAP membranes, KvAP is unable to open due to large positive voltage shifts in its mid-point of activation. Based on these results, it has been hypothesized that non-phosphate lipids stabilize the down (resting) conformation of the voltage sensor. We have tested this idea by studying the influence of non-phospholipids on the gating properties of channels with inverse electromechanical coupling. In contrast to most Kv channels, the pore domain of hyperpolarization-activated channels opens with the downward movement of S4 (at hyperpolarizing potentials). Therefore, for any hyperpolarization-activated channel, reconstitution in DOTAP should stabilize the down state of the VSD, favoring the open state and not the closed state. We carried out a CW-EPR analysis of the local structure and dynamics of the prokaryotic hyperpolarization activated potassium channel MVP, after reconstitution in either PC:PG (3:1) or DOTAP liposomes, in the absence of a resting potential. We focused on residues in the S4, S4-S5 linker, and lower S6 of MVP as a way to monitor the key regions that participate in voltage sensing and gate coupling. In PC:PG phospholipids, the inner bundle gate of MVP is closed, as seen from strong spin-spin coupling between residues lining the S6. In contrast, our findings suggest that DOTAP biases the conformation of the VSD in MVP towards the down state, which leads to a structural reorganization of the lower S5 region and conformational changes in the pore domain. The activation gate displays key hallmarks associated with the open conformation. These lipid-driven structural changes point to a working model for the inverse electromechanical coupling in hyperpolarization-activated channels.

Amplitude control of the Goos–Hänchen shift via a Kerr nonlinearity

The influence of the Kerr nonlinearity on the group index of a dispersive intracavity medium is revisited using a Raman gain based scheme to obtain amplitude control of the Goos–Hänchen (GH) shift in the reflected light. The intracavity medium exhibits a Raman gain process which is accompanied by anomalous dispersion, i.e., superluminal pulse propagation (Dogariu et al 2000 Nature 406 277). In the presence of a Kerr field, the gain–dispersion properties of the intracavity medium are modified, which leads to enhancement in the positive and negative group indices of the medium. The behavior of the GH shift in the reflected light due to the enhancement in the group indices in the presence of the Kerr field is investigated, and relatively large positive and negative GH shifts can be obtained.

Surface wave-induced enhancement of the Goos–Hänchen shift in single negative one-dimensional photonic crystal

The Goos–Hänchen (GH) shift in one-dimensional photonic crystal (1DPC), composed of alternate ε-negative and μ-negative materials, is theoretically investigated. It is demonstrated that larger shifts can be obtained when surface modes are excited. It is also found that the magnitude of the lateral GH shift is closely related to intrinsic loss factor. The results show that for a definite value of loss and for values larger than that, backward surface waves which lead to negative lateral GH shifts can be excited. On the other hand, there are large positive GH shifts for small loss factor less than aforementioned definite loss. The GH shift is very sensitive to the thickness of air gap which is necessary to excitation of the surface waves.

High current stress effects in amorphous-InGaZnO4 thin-film transistors

Amorphous-InGaZnO4 (a-IGZO) thin-film transistors (TFTs) on glass undergo large positive threshold voltage shifts (ΔVTH) under high current stress (HCS)—a consequence of Joule heating of the active-layer. Here, we show that when the active layer is split into smaller parts, HCS induces negligible ΔVTH. When the active layer heats up during HCS, conducting electrons in the channel gain enough energy to surmount the energy barrier at the active-layer/gate-insulator interface and become trapped into deep states inside the gate-insulator. Splitting the active-layer into smaller parts increases the surface area for heat dissipation, resulting in the elimination of these self-heating effects.

A Mutation in the Voltage-Sensor of Kv7.1 Prevents PKA Activation of IKs to Elicit Concealed Type 1 Long QT Syndrome during Stress

Long QT syndrome is associated with prolongation of the corrected QT interval (QTc) and increased risk for ventricular arrhythmias. LQT1 is caused by loss-of-function mutations in the KCNQ1-encoded Kv7.1 α-subunit which mediates the slowly activating delayed rectifier K+ current (IKs) in the heart. A family with a KCNQ1 missense mutation (I235N) in the voltage-sensor of Kv7.1 has concealed LQT1 at rest (QTc, 452±5ms) but shows marked paradoxical QTc prolongation (534±16ms) during the recovery phase of treadmill stress testing. This abnormal recovery response is blunted in patients taking β-adrenergic blockers (487±11ms). Voltage-clamping experiments using HEK293 cells expressing WT or I235N with the Kv7.1 β-subunit KCNE1 showed that I235N decreased KCNQ1 current (IKCNQ1) by 93% and caused a large positive shift in the midpoint potential for activation (V1/2). However, cells co-expressing WT and I235N (to mimic the patients' genotypes) showed only a small decrease in IKCNQ1 (∼30%) and shift in V1/2. Since excessive QTc prolongation in I235N patients appears secondary to β-adrenergic stimulation, we tested whether I235N prevented PKA activation of IKCNQ1. In cells expressing WT, PKA stimulation with forskolin and IBMX increased IKCNQ1 by 64%, but it did not increase IKCNQ1 in cells co-expressing WT and I235N. Computational simulations using a ventricular action potential (AP) model showed that reducing the IKs component by 30% increased the AP duration at 90% repolarization (APD90) by only 1.6%. However, incorporating β-adrenergic signaling showed that reducing the IKs component by 30% and preventing its activation by PKA increased the APD90 by 7.1%. We conclude I235N modestly affects basal QTc, IKs, and APD90, but it prevents PKA activation of IKs to cause a dangerous prolongation in the QTc/APD90 during β-adrenergic stimulation.

New ternary ligands consisting of an N4 bridging ligand and two terpyridines, and their Co(ii) and Ni(ii) dinuclear complexes. Structure, redox properties, and reaction with acid

Two ternary ligands consisting of two 2,2′:6′,2′′-terpyridines and one N4-quadridentate μ2,η(2)-bridging ligand were synthesized. The N4 bridge is 1,4-bis(2-pyridyl)phthalazine in ligand 1, and 3,6-bis(2-pyridyl)pyridazine in ligand 2. Two Co(II) dinuclear complexes [(1)Co2(μ-OH)]3+ and [(2)Co2(μ-OH)]3+, and one Ni(II) dinuclear complex [(1)Ni2(μ-Cl)]3+ were obtained. In the crystal structures of [(1)Co2(μ-OH)]3+ and [(1)Ni2(μ-Cl)]3+, two pyridine rings are twisted around the pyridine-phthalazine bonds to avoid steric repulsion between the hydrogen atoms. The pyridine rings also showed a significant tilt from the octahedral coordination plane, which causes the large positive shift of the first reduction potentials. Upon the addition of a proton, the cobalt dinuclear complexes can release one cobalt ion selectively, and the dinuclear complexes can be easily restored by the addition of a tertiary amine.

Effect of NaCl on the conformational stability of the thermophilic γ-glutamyltranspeptidase from Geobacillus thermodenitrificans: Implication for globular protein halotolerance

The transpeptidation activity of γ-glutamyltranspeptidase from Geobacillus thermodenitrificans (GthGT) is negligible and the enzyme is highly thermostable. Here we have examined the effect of concentrated NaCl solutions on structure, stability, dynamics and enzymatic activity of GthGT. The protein exhibited hydrolytic activity over a broad range of NaCl concentrations. Even at 4.0M NaCl, GthGT retained more than 90% of the initial activity and showed unaltered fluorescence emission, secondary structure and acrylamide quenching on tryptophan fluorescence. Furthermore, at 2.8M and 4.0M NaCl the temperature-induced unfolding profiles are dramatically changed with large (>20°C) positive shifts in the denaturation temperature. These features make GthGT an ideal system to be used in industrial processes that require high temperatures and high-salt environments. A general explanation of the NaCl effect by means of a statistical thermodynamic model is also provided, together with an analysis of residue distribution between protein surface and interior in 15 non-redundant families of halophilic and non-halophilic proteins. The results are in line with a comparative sequence and structural analysis between halophilic and non-halophilic γ-glutamyltranspeptidases which revealed that a major role in halotolerance should be played by solvent exposed negatively charged residues.

Role of tunneling layer in graphene-oxide based organic nonvolatile memory transistors

This paper demonstrates non-volatile memory transistor using solution processable graphene oxide (GO) as charge storage nodes in the configuration, p++Si/SiO2/GO/Tunneling layer/Pentacene/Au. The tunneling layers are polymethylmethacrylate (PMMA) and polyvinylphenol (PVP). GO film could be deposited as single layered flakes with a uniform distribution using spin coating technique. The devices with PMMA as charge tunneling layer exhibited higher mobility and on/off ratio than PVP based devices. The devices show a large positive threshold voltage shift (∼24V for PMMA and ∼15V for PVP) from initial value during programming at gate voltage of +80V kept for 10s. The transfer curves can be restored approximately to its initial condition by applying an erasing voltage of −30V for 10s for both the devices. Since such a large shift is not observed without GO layer, we consider that memory effect was due to electron trapping in GO. Further, retention of the initial memory window was measured to be 63% and 37% after 3000s for PMMA and PVP based devices, respectively.

Effect of POCl<sub>3</sub> Annealing on Reliability of Thermal Oxides Grown on 4H-SiC

We have evaluated the reliability of POCl3-annealed oxides on 4H-SiC using time-zero dielectric breakdown (TZDB), constant current time-dependent dielectric breakdown (CC-TDDB), and high-frequency capacitance-voltage (C-V) measurements after electron injection. The POCl3 annealing does not deteriorate oxide breakdown field very much, still keeping an average value of larger than 9 MV/cm. However, the electron injection into POCl3-annealed oxide brings negative charges easily. From the C-V measurements, the POCl3-annealed capacitors were found to indicate a large positive flatband voltage shift after electron injection. Phosphorus atoms in the oxide may be related to the trapping site of injected electrons. The distribution and density of phosphorus in the oxide should be optimized to realize highly reliable 4H-SiC MOSFETs with high performance.

Optical properties of HgTe colloidal quantum dots

Room temperature photodetection with HgTe colloidal quantum films is reported between 2 and 5 µm for particles of sizes between ∼5 and ∼12 nm diameter, and photodetection extends to 7 µm at 80 K. The size-tuning of the absorption of HgTe colloidal quantum dots, their optical cross section and the infrared absorption depth of films are measured. The tuning with radius is empirically given by , where R is in nm. The optical cross section of the colloidal dots at 415 nm is approximately proportional to their volume and given by atom. The size-dependent optical cross section at the band edge ∼1.5 × 10−15 cm2 is consistent with the expected oscillator strength of the quantum dots. The absorption depth of HgTe colloidal dot films is short, about 1–2 µm, which is an advantage for thin film devices. These properties agree rather well with the expectation from the k ⋅ p model. HgTe colloidal quantum dot thin films show a strong tuning with temperature with a large positive thermal shift between 0.4 and 0.2 meV K−1, decreasing with decreasing size within the size range studied and this is attributed primarily to electron–phonon effects.

Regulation of Redox Potential of a Pterin Derivative Bound to a Ruthenium(II) Complex by Intermolecular Hydrogen Bonding with Nucleobases

Potential control: A RuII-bound pterin forms a stable hydrogen-bonding adduct with a guanine derivative through three-point recognition. A large positive shift of the reduction potential of the pterin ligand up to +320 mV is observed (see picture). For the thymine derivative, the mode of hydrogen bonding is altered. Regulation of redox potentials of a pterin coenzyme by noncovalent interaction is demonstrated. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typeset. They are made available as submitted by the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.