Partial Gap Research Articles

At scale adoption of Green Hydrogen in Indian Industry: Costs, subsidies and policies

Indian Industry is gearing up to leverage hydrogen's potential as an alternative to fossil fuels. This paper answers three related questions that would help scale green hydrogen in Indian industry vital for sustainable development. First, is there an economic case for green hydrogen production in terms of cost-competitiveness compared to other hydrogen production sources i.e., coal and natural gas? Second, what is the cheapest way to subsidize green hydrogen? Third, how policies and frameworks can be designed to produce and procure green hydrogen at scale? Key findings include. First, at present, the levelized cost of green hydrogen is USD 4.45/Kg, which reduces to USD 3.26/Kg by 2025 and USD 2.45/Kg by 2030. The present cost of green hydrogen is nearly twice that of hydrogen produced from coal and about four times that of hydrogen produced from natural gas. In the absence of policy support, green hydrogen may become competitive in India only after 2030. Second, upfront Capital expenditure subsidy is the most suited cost-effective policy option with partial viability gap coverage, and its combination with Generation based incentive for 100 % coverage. Third, subsidies need to be complemented with deployment-based policies such as hydrogen portfolio standard (HPS) for scale adoption of green hydrogen in Indian industry.

Electronic correlations and partial gap in the bilayer nickelate La3Ni2O7

The discovery of superconductivity with a critical temperature of about 80 K in La3Ni2O7 single crystals under pressure has received enormous attention. La3Ni2O7 is not superconducting under ambient pressure but exhibits a transition at T ∗ ≃ 115 K. Understanding the electronic correlations and charge dynamics is an important step towards the origin of superconductivity and other instabilities. Here, our optical study shows that La3Ni2O7 features strong electronic correlations which significantly reduce the electron’s kinetic energy and place this system in the proximity of the Mott phase. The low-frequency optical conductivity reveals two Drude components arising from multiple bands at the Fermi level. The transition at T ∗ removes the Drude component exhibiting non-Fermi liquid behavior, whereas the one with Fermi-liquid behavior is barely affected. These observations in combination with theoretical results suggest that the Fermi surface dominated by the Ni-d3z2−r2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{3{z}^{2}-{r}^{2}}$$\\end{document} orbital is removed due to the transition at T ∗. Our experimental results provide pivotal information for understanding the transition at T ∗ and superconductivity in La3Ni2O7.

Spin–Orbit Coupling Free Nonlinear Spin Hall Effect in a Triangle-Unit Collinear Antiferromagnet with Magnetic Toroidal Dipole

We investigate emergent conductive phenomena triggered by collinear antiferromagnetic orderings. We show that an up-down-zero spin configuration in a triangle cluster leads to linear and nonlinear spin conductivities even without the relativistic spin–orbit coupling; the linear spin conductivity is Drude-type, while the nonlinear spin conductivity has Hall-type characterization. We demonstrate the emergence of both spin conductivities in a breathing kagome system consisting of a triangle cluster. The nonlinear spin conductivity becomes larger than the linear one when the Fermi level lies near the region where a small partial band gap opens. Our results indicate that collinear antiferromagnets with triangular geometry give rise to rich spin conductive phenomena.

Experimental study of flow control on tip leakage flow in variable geometry linear turbine cascades with different pivot layouts

Variable geometry turbines are essential for adjusting operational conditions in industrial gas turbines and variable cycle engines. These adjustments necessitate partial gaps at both ends of the variable guide vanes to alter the turning angle, consequently introducing an aerodynamic performance penalty. Moreover, the pivot layout profoundly influences aerodynamic losses. Research on turbine cascades that considers various partial gap layouts is limited, particularly in terms of experimental studies, which are rarely conducted. This study aims to diminish aerodynamic losses and augment the efficiency of gas turbines by examining the impact of pivot layouts on partial gap clearance and secondary flow. It further investigates the effectiveness of flow control strategies at the blade tip across different pivot configurations within a variable geometry turbine cascade, utilizing pneumatic probe scanning and surface oil flow visualization techniques. The results reveal that employing a cavity at the tip can significantly reduce aerodynamic losses in schemes both with and without a pivot, achieving maximum loss reductions of 15.8% and 3.7%, respectively. Additionally, a narrower squealer width can further decrease these losses. However, with a pivot located at the tip, the resulting separation flow and wake vortex become predominant sources of losses. The presence of the pivot weakens the tip leakage flow rate and the intensity of the tip leakage vortex (TLV), thus diminishing the effectiveness of cavity tip flow control. The cavity moderates TLV and enhances the interaction between TLV and the wake vortex, leading to increased aerodynamic losses.

A Recipe for Eccentricity and Inclination Damping for Partial-gap Opening Planets in 3D Disks

In a previous paper, we showed that, like the migration speed, the eccentricity damping efficiency is modulated linearly by the depth of the partial gap a planet carves in the disk surface density profile, resulting in less efficient e-damping compared to the prescription commonly used in population synthesis works. Here, we extend our analysis to 3D, refining our e-damping formula and studying how the inclination damping efficiency is also affected. We perform high-resolution 3D locally isothermal hydrodynamical simulations of planets with varying masses embedded in disks with varying aspect ratios and viscosities. We extract the gap profile and orbital damping timescales for fixed eccentricities and inclinations up to the disk scale height. The limit in gap depths below which vortices appear, in the low-viscosity case, happens roughly at the transition between classical type-I and type-II migration regimes. The orbital damping timescales can be described by two linear trends with a break around gap depths ∼80% and with slopes and intercepts depending on the eccentricity and inclination. These trends are understood on physical grounds and are reproduced by simple fitting formulas whose error is within the typical uncertainty of type-I torque formulas. Thus, our recipes for the gap depth and orbital damping efficiencies yield a simple description for planet–disk interactions to use in N-body codes in the case of partial-gap opening planets that is consistent with high-resolution 3D hydrosimulations. Finally, we show examples of how our novel orbital damping prescription can affect the outcome of population synthesis experiments.

On the Secondary Flow System of an Aggressive Inter Compressor Duct

Abstract In contrast to the highly optimized rotating components, the inter compressor duct (ICD) is offering a high potential for further improvements. Due to a more aggressive design, the length of the whole engine can be reduced. Shorter and thus lighter engines are leading to further fuel savings for the next engine generation. The design of current ICDs is very conservative because of high uncertainties in design space. An extensive test campaign on two highly aggressive ICDs has been conducted at an annular cascade at German Aerospace Center (DLR) Cologne to explore these limitations. The test section consists of low-pressure compressor (LPC)-OGVs, struts, and high-pressure compressor (HPC)-inlet guide vanes (IGVs). To simulate the influence of the last rotor of the LPC and to vary the incidence of the OGV, a moveable swirler is placed in front of the OGV. This simplification results in differences compared to a real rotor outlet flow. Due to geometric constraints, the ability to move the swirler can only be achieved by adding partial gaps in the rear part of the swirler at hub and shroud. These gaps have a huge impact on the secondary flow structure of the swirler outflow and therefore on the inflow of the ICD. In this article, the secondary flow system of an aggressive ICD is analyzed in detail by the means of experimentally validated computational fluid dynamics (CFD) simulations. Special attention is given to the influence of the nonrotating swirler on the secondary flow system. Furthermore, a recommendation for future experimental setups with respect to the described effects is concluded.

Overstability of the 2:1 mean motion resonance: Exploring disc parameters with hydrodynamic simulations

Context. Resonant planetary migration in protoplanetary discs can lead to an interplay between the resonant interaction of planets and their disc torques called overstability. While theoretical predictions and N-body simulations hinted at its existence, there was no conclusive evidence until hydrodynamical simulations were performed. Aims. Our primary purpose is to find a hydrodynamic setup that induces overstability in a planetary system with two moderate-mass planets in a first-order 2:1 mean motion resonance. We also aim to analyse the impact of key disc parameters, namely the viscosity, surface density, and aspect ratio, on the occurrence of overstability in this planetary system when the masses of the planets are kept constant. Methods. We performed 2D locally isothermal hydrodynamical simulations of two planets, with masses of 5 and 10 $M_ oplus $, in a 2:1 resonance. Upon identifying the fiducial model in which the system exhibits overstability, we performed simulations with different disc parameters to explore the effects of the disc on the overstability of the system. Results. We observe an overstable planetary system in our hydrodynamic simulations. In the parameter study, we note that overstability occurs in discs characterised by low surface density and low viscosity. Increasing the surface density reduces the probability of overstability within the system. A limit cycle was observed in a specific viscous model with $ nu $. In almost all our models, planets create partial gaps in the disc, which affects both the migration timescale and structure of the planetary system. Conclusions. We demonstrate the existence of overstability using hydrodynamic simulations but find deviations from the analytic approximation and show that the main contribution to this deviation can be attributed to dynamic gap opening.

The smallest structures in Saturn’s rings from UVIS stellar occultations

On the largest scales Saturn’s rings are often thought of as axisymmetric annuli varying only radially in optical depth with exceptions of spiral waves and eccentric ringlets. But on scales smaller than a few tens of km yet still larger than the largest common ring particles, the assumption of azimuthal symmetry breaks down. Structures such as “straw” in the troughs of density waves, partial gaps around propeller moonlets, and ephemeral particle aggregates such as self-gravity wakes are responsible for the predominant variations in optical depth. During the 13 year Cassini mission, the Ultraviolet Imaging Spectrograph (UVIS) high speed photometer (HSP) measured 80 stellar chord occultations of Saturn’s main rings. In the vicinity of the minimum ring plane radius of each chord, the occultation line-of-sight slewed across the ring plane tangent to the Keplerian motion of the ring particles. These occultations measured ultraviolet light in the wavelength range 110–190 nm with 1- or 2-ms ms integration times, providing optical depth measurements with resolution comparable to the Fresnel scale of ∼10 m in the frame co-moving with the local Keplerian speed. These high-resolution chord occultations reach their minimum ring radii over a broad range of radial locations within Saturn’s main rings and resolve non-axisymmetric structures in a wide variety of ring regions. We measure the azimuthal length scales and optical depth profiles of “ghosts”, or azimuthally limited gaps with radial scales less than 30 m (Baillié et al., 2013), in the C ring plateaus. We measure the length scale of transparent gaps and self-gravity wakes in the peaks and troughs of spiral density waves. We present optical depth profiles which resolve axisymmetric waves in the A and B rings and constrain the azimuthal length scale over which the waves remain axisymmetric to ∼1000 km. We combine autocorrelation length scales from stellar occultations which cut across the minimum ring radius of a chord occultation with line-of-sight trajectories from other occultations which are not tangent to the rings to constrain the morphology of the azimuthally and temporally averaged mesoscale structures at that ring radius. 2D autocorrelation profiles from stellar occultations show self-gravity wakes and axisymmetric waves often coexisting.

Planetesimal and planet formation in transient dust traps

The ring-like structures in protoplanetary discs that are observed in the cold dust emission by ALMA might be explained by dust aggregates trapped aerodynamically in pressure maxima. We investigate the effect of a transient pressure maximum that develops between two regimes with different turbulent levels. We study how such a pressure maximum collects dust aggregates and transforms them into large planetesimals and Moon-mass cores that can further grow into a few Earth-mass planets by pebble accretion, and eventually into giant planets by accreting a gaseous envelope. We developed a numerical model, incorporating the evolution of a gaseous disc, the growth and transport of pebbles, N-body interactions of growing planetary cores, and their backreaction to a gas disc by opening a partial gap. Planetesimal formation by streaming instability is parametrised in our model. A transient pressure maximum efficiently accumulates dust particles that can grow larger than millimetre-sized. If this happens, dust aggregates can be transformed by the streaming instability process into large planetesimals, which can grow further by pebble accretion according to our assumptions. As the gas evolves towards a steady state, the pressure maximum vanishes, and the concentrated pebbles not transformed into planetesimals and accreted by the growing planet drift inward. During this inward drift, if the conditions of the streaming instability are met, planetesimals are formed in the disc within a wide radial range. A transient pressure maximum is a favourable place for planetesimal and planet formation during its lifetime and the concentration of pebbles induces continuous formation of planetesimals even after its disappearance. In addition, the formation of a planet can trigger the formation of planetesimals over a wide area of the protoplanetary disc.

Experimental investigation of secondary flow losses in a variable geometry linear turbine cascade with winglet tip

Variable geometry turbines (VGT) hold a crucial role in gas turbines and variable cycle engines (VCE) by allowing adjustments to different operational conditions. In order to realize the adjustable function of the VGT stator blade, there will be partial gap structure at both ends of the stator blade, which will lead to partial leakage flow and serious secondary flow loss at the blade end that cannot be ignored, especially in a large angle adjustment range. At present, there are few researches on turbine cascades considering the real partial gap structure and winglet tip, and the numerical simulation calculation is mainly used, while the in-depth study using wind tunnel test is rarely seen. Therefore, this study attempts to analyze the internal flow characteristics of variable geometry turbine cascade by using five-hole pneumatic probe scanning and surface oil flow visualization, and discusses the mechanism of controlling partial clearance leakage flow and reducing secondary flow loss in the cascade by using winglet tip flow control technology. The winglet offset distance and the change of the relationship between the pivot and the clearance position on the flow field and flow loss is studied experimentally for the first time. The results show that the influence mechanism of winglet tip applied in VGT partial gap is quite different from that of typical blade tip clearance application, and more consideration should be given to the influence of pivot structure. Reasonable parameter selection can achieve a maximum loss reduction of 13.4 % and 20.2 % with and without pivot, respectively, while the unreasonable flow control scheme may lead to the loss or even increase with pivot. The interaction between the new secondary flow structure induced by pivot in the gap and other gap leakage flows is analyzed to explore the new mechanism of using winglet tip to reduce the loss of gap leakage flow.

Nanoscale visualization and spectral fingerprints of the charge order in ScV6Sn6 distinct from other kagome metals

Charge density waves (CDWs) in kagome metals have been tied to many exotic phenomena. Here, using spectroscopic-imaging scanning tunneling microscopy and angle-resolved photoemission spectroscopy, we study the charge order in kagome metal ScV6Sn6. The similarity of electronic band structures of ScV6Sn6 and TbV6Sn6 (where charge ordering is absent) suggests that charge ordering in ScV6Sn6 is unlikely to be primarily driven by Fermi surface nesting of the Van Hove singularities. In contrast to the CDW state of cousin kagome metals, we find no evidence supporting rotation symmetry breaking. Differential conductance dI/dV spectra show a partial gap Δ1CO ≈ 20 meV at the Fermi level. Interestingly, dI/dV maps reveal that charge modulations exhibit an abrupt phase shift as a function of energy at energy much higher than Δ1CO, which we attribute to another spectral gap. Our experiments reveal a distinctive nature of the charge order in ScV6Sn6 with fundamental differences compared to other kagome metals.

Theoretical study of CDW phases for bulk NbX2 (X = S and Se).

In most two-dimensional transition metal chalcogenides, the superconducting phase coexists with the charge density wave (CDW) phase. There exists at least one case, i.e. bulk 2H-NbS2, that does not conform to this picture. Scientists have shown great interest in trying to experimentally find the CDW phase of bulk NbS2 since 1975. Is there any theoretically more stable thermodynamic state than its higher-temperature metal phase, especially in the case of charge injection? Theoretically more stable CDW bulk configurations (TC for 2H-NbS2 and TTs for 2H-NbSe2) with partial pseudo energy gaps were predicted through the harmonic phonon softening theory and first-principles calculations. The ratios of larger to smaller pseudo gaps around K-H segment in the Brillouin zone for CDW phases are basically equal to those of superconductivity phases for bulk 2H-NbX2 (X = S and Se). The CDW phase should coexist with its superconductor state below the critical temperature rather than the metal phase for bulk 2H-NbS2. The presence of CDW phase should be more easily observed experimentally when the injected charge reaches 0.5e/Nb18S36 for bulk 2H-NbS2. Our calculations of density of state (DOS) indicated that, during Nb atoms contracting to form the CDW phases with symmetry breaking in the in-plane direction, dominant conductive carriers are always of p-type for bulk 2H-NbS2 while the alternation of carrier type from p-type to n-type occurs for bulk 2H-NbSe2. The Fermi level continuously drops and then the M-L segment of the out-of-plane energy band emerges from the Fermi surface, which corresponds to the reversal of p-n type sign. Lifshitz transition of pocket-vanishing types occurs in the out-of-plane direction without symmetry breaking during the geometrical structural phase transition for bulk 2H-NbSe2. Our calculations have theoretically addressed the long-standing coexistence issue of CDW and superconducting phases.

Obesity intervention evidence synthesis: Where are the gaps and which should we address first?

Health professionals and policymakers rely on evidence synthesized from high quality research studies. Yet, there remain unanswered questions about how to prevent and treat obesity. In this research project, international practice guidelines and Cochrane systematic reviews were examined in order to identify gaps in the synthesized obesity intervention evidence base. One hundred and forty-two partial or complete gaps were found. Systematic review questions to address these gaps were formulated and subjected to a prioritization consultation process with 36 international obesity expert stakeholders. Forty-three review questions were priority-assessed. The top 10 ranked review questions received support from at least 75.0% of stakeholders. The leading questions focused on preventive and community-based approaches, including those delivered through primary-care. Children within the context of their families were a highly-prioritized target group, as were persons with diabetes or disabilities. Experts also prioritized reviews to determine which elements of programs are the most effective, and by which mode they are best delivered. Experts recommended that negative, psycho-social, and longer-term outcomes be captured in reviews. We request reviewers and funders to strongly consider addressing the top 10 leading prioritized review questions presented here.

Entrapment and extraction of wheelchairs at flange gaps with and without flange gap fillers at pedestrian railway crossings

Purpose Where pedestrian crossings meet rail tracks, a flange gap allows the train wheel flanges to pass. This gap can be hazardous for wheelchair users as castor wheels may become trapped. While compressible gap fillers can eliminate the flange gap, fillers are subject to wear, pose a derailment hazard to light rail vehicles and can strip grease from passing wheels. These issues could be mitigated by partially filling the flange gap with a compressible filler. The aim was to investigate the risk of entrapment and ease of extraction of wheelchair castors from flange gaps fully and partially filled with compressible fillers, and assess ride quality. Materials and methods Entrapment risk and ease of extraction for four wheelchairs were tested at various crossing angles with flange gap fillers. Twelve wheelchair users tested ease of extraction and ride quality for partially and fully filled flange gaps. Results It was found that risk of entrapment is low if a standards-compliant crossing with open flange gaps is traversed in a straight line. However, castors can become trapped if the user alters direction to avoid an obstacle or if the crossing surface is uneven. Once trapped, castors are extremely difficult to remove without external assistance. Conclusions Flange gap fillers that reduce the gap to 10 mm or less eliminate entrapment while retaining acceptable ride quality. Filling flange gaps or leaving a residual gap depth of less than 10 mm is the best option to eliminate risk of entrapment and ensure good ride quality for wheelchair users. IMPLICATIONS FOR REHABILITATION Rail crossings flange gaps pose an entrapment hazard for wheelchair users Partial or complete flange gap fillers may reduce entrapment but require research Rehabilitation professionals need to educate wheelchair users on techniques to cross flange gaps safely Consumers and health professionals can consult rail operators to partially fill flange gaps

Driven charge density modulation by spin density wave and their coexistence interplay in SmFeAsO: A first-principles study

We use density functional theory to investigate effects of spin-orbit coupling and single-stripe-type antiferromagnetic (sAFM) ordering on the crystal structure and electronic properties of SmFeAsO. The results indicate that AFM ordering causes the crystal structure transition from tetragonal to orthorhombic, along with increase in the height of As atoms from Fe layer due to magnetostriction. It also leads to the opening of partial band gaps, the emergence of a prominent peak near Fermi energy (EF) in the density of states (DOS) and a reduction in Fermi surface nesting. The study finds a correlation between the calculated area under the DOS curve, spanning from EF to the first peak above it, and the optimal electron-doped concentration required for inducing superconductivity in SmFeAsO. The findings suggest that spin and charge density waves can play important roles in the superconducting mechanism of Fe-based superconductors. Our calculations demonstrate that spin-orbit coupling reduces electronic correlation.

Complex band structure in viscoelastic thin plate phononic crystals

Phononic crystals (PnCs) are artificial composites designed by a periodic arrangement of two or more materials with different properties and/or geometry, in order to tailor the propagation of mechanical waves. The complex band structures of PnC thin plates, consisting of a hard matrix material reinforced by inclusions of soft viscoelastic material (HS-PnC), and vice-versa (SHPnC), are investigated. In general, elastic plate structures can be modelled using the Kirchhoff- Love theory, which is suitable for thin plates in low frequencies. However, there is a lack of knowledge concerning the effects of viscoelastic constituents on the complex band structure of flexural Bloch waves in PnC thin plates. In this study, an extended plane wave expansion (EPWE) method is used to compute the complex band structures of VPnC thin plates. The evanescent behaviour of periodic plates for the cases HS-PnC and SH-PnC is calculated, and the results show that the first creates flat bands for wave localization and the second opens up complete and partial Bragg scaterring band gaps.

Temporal Evolution and Fluence Dependence of Band Structure in Photoexcited Ta2Ni0.9Co0.1Se5 Probed by Time- and Angle-Resolved Photoemission Spectroscopy

We have investigated the temporal evolution and fluence dependence of band structure in Ta2Ni0.9Co0.1Se5 by means of time- and angle-resolved photoemission spectroscopy (tr-ARPES). With the fluence of 3.00 mJ cm−2 and the delay time of 170 fs, the conduction band crossing the Fermi level (EF) and the valence band reaching EF are observed indicating the photoinduced semimetal phase. However, at the delay time of 70 fs, the valence band top does not reach EF creating a partial gap or a pseudogap, and the transition from the excitonic insulator state to the semimetal state is not completed. The conduction band crossing EF is observed even with the shorter delay time (down to 50–70 fs) and/or the lower fluence (down to 0.32 mJ cm−2). On the other hand, the valence band top stays well below EF up to the fluence of 1.39 mJ cm−2 even at the delay time of 160–170 fs. The different optical responses of the valence and conduction bands suggest a vital role of the lattice fluctuations pointed out by Nakano et al. [Phys. Rev. B 98, 045139 (2018)] on the residual pseudogap at 70 fs after the photoexcitation.

Depression in older adults. What are the differences in clinical practice?

Management of depression in the elderly is a growing public health issue in France. The objective of this study was to compare practitioners' perception of depression severity (i.e., intensity and suicidal risk) and clinical practice (i.e., clinical assessment and medication choice) in elderly versus younger adult patients with major depression. The method consisted of an online questionnaire completed by general practitioners and psychiatrists. Respondents'answers to a fictive case of a patient with major depression were randomized according to the patient's age, if the patient'age was either 40 or 70 years old. We assessed the perceived intensity of the depression, the perceived suicidal risk, the prescription of biological tests and cerebral imaging, and of antidepressive or other psychotropic medications. 102 completed forms were included. Data indicate that there were no significant differences in terms of perceived depression intensity and suicidal risk according to the patients'age. The prescription of biological tests was systematic in both groups, but a significant difference was observed in terms of prescription of brain imaging (71% of respondents for the 70-year-old patient versus 43% for the 40-year-old patient, p <0.005), use of tetracyclic antidepressant (33% if aged 70years versus 2% if aged 40 years, p <0.001) and other psychotropic non-antidepressant medications (69% if aged 70 years versus 85% if aged 40 years, p<0.05). This study did not show any significant difference in the perception of depression according to age. However, it highlights differences in terms of practical care according to age. These results suggest a partial gap between clinical practice and guidelines for the management of major depression in older adults, reflecting the need to favor the dissemination of guidelines and strengthen research for this population.

Charge-density wave associated with higher-order Fermi-surface nesting in monolayer VS2

Fermi-surface (FS) nesting originating from Peierls’ idea of electronic instabilities in one-dimensional materials is a key concept to stabilize charge-density wave (CDW), whereas its applicability to two-dimensional (2D) materials is under intensive debate. Here we report unusual CDW associated with the higher-order FS nesting in monolayer 2D VS2. Angle-resolved photoemission spectroscopy and scanning tunneling microscopy uncovered stripe CDW with sqrt {21} R10.9^circ times sqrt 3 R30^circ periodicity together with an energy-gap opening on the entire FS. We suggest that this CDW involves the higher-order FS-nesting vector 2q twice larger than that of the normal one (q), as supported by the anomalies in the calculated phonon dispersion and electronic susceptibility. The present results suggest that the cooperation of q and 2q nesting leads to the fully gapped CDW state unlike the case of conventional single q nesting which produces a partial gap, pointing to an intriguing mechanism of CDW transition.

Description Versus Experience for Decisions About Discounts

Abstract The description–experience gap in risky choice behavior is the finding that people tend to overweight rare events when making description-based decisions, whereas they tend to underweight rare events when making experience-based decisions. In the present study, the authors investigated whether the gap, which is studied mainly in the context of monetary gambles, generalizes to the context of retail discounts in the consumer domain. In 3 experiments, subjects made description- or experience-based decisions about safe and risky discounts (scratch-and-save promotions). When discounts were expressed as percentages without a reference point, there was no evidence of a gap (Experiment 1). When discounts were expressed in dollars with an explicit reference point, there was evidence of a partial gap, such that experience subjects chose the risky promotion more often than description subjects did but only when the large discount occurred with high probability (Experiments 2 and 3). In all experiments, experience subjects tended to be more rational than description subjects when choosing between promotions with different expected values. Possible reasons for the pattern of results are discussed.