Companies have the opportunity to better engage potential customers by presenting products to them in a highly immersive virtual reality (VR) shopping environment. However, a minimal amount is known ...about why and whether customers will adopt such fully immersive shopping environments. We therefore develop and experimentally validate a theoretical model, which explains how immersion affects adoption. The participants experienced the environment by using a head-mounted display (high immersion) or by viewing product models in 3D on a desktop (low immersion). We find that immersion does not affect the users' intention to reuse the shopping environment, because two paths cancel each other out: Highly immersive shopping environments positively influence a hedonic path through telepresence, but surprisingly, they negatively influence a utilitarian path through product diagnosticity. We can explain this effect via low readability of product information in the VR environment and expect VR's full potential to develop when the technology is further advanced. Our study contributes to literature on immersive systems and IS adoption research by introducing a research model for the adoption of VR shopping environments. A key practical implication of our study is that system designers need to pay special attention to the current state of technology when designing VR applications.
This study experimentally evaluates the performance of partial equilibrium mechanisms when different sectors run their mechanisms separately, despite the existence of complementarity between them. In ...our simple laboratory experiment setting that includes two sectors, each sector runs the top-trading-cycle mechanism. There is a Pareto-dominant equilibrium, but it requires coordination across sectors. Our results show that coordination failure occurs more frequently when there is asymmetry between the two sectors compared with the one-sector benchmark, even without inter-sectoral complementarity. When mechanisms are run sequentially across the two sectors, such failure is substantially reduced, compared with when they are run simultaneously.
Unsaturated flow influences both the seawater extent under steady‐state conditions and the propagation of tides in coastal aquifers. However, its effects on salt distributions in tidally influenced ...coastal aquifers are little investigated. The present study used numerical simulations and data from laboratory experiments to analyze the effects of unsaturated flow on density‐dependent solute transport in coastal unconfined aquifers. The effects of the inland boundary condition (i.e., constant‐head or constant‐flux) were tested. Compared to a stable sea level, the results show that unsaturated flow has a more pronounced influence on salt distributions in coastal unconfined aquifers when tides are considered, regardless of the type of inland boundary condition. Neglect of unsaturated flow effects leads to expansion of the upper saline plume (USP), shrinkage of the saltwater wedge (seaward movement of saltwater wedge), and overestimation of water and salt exchange across the aquifer‐ocean interface. This is caused by a lower head in the nearshore area during high‐tide periods with the unsaturated zone effects removed. Thus, without the unsaturated zone, stronger head gradients within the nearshore aquifer occur at high tide, leading to stronger tidally driven seawater infiltration and hence a larger USP. Counterintuitively, ignoring unsaturated flow effects leads to greater average inland head over a tidal period, which shifts the saltwater wedge seaward. It is concluded that unsaturated zone effects should not be neglected for modeling tide‐affected seawater intrusion, especially if quantification of near‐shore conditions is important.
Key Points
Tidal fluctuations intensify unsaturated flow effects on salt distributions in coastal unconfined aquifers
Neglecting unsaturated flow effects leads to a more extensive upper saline plume and shrinking of the saltwater wedge
Neglecting unsaturated flow effects intensifies the water and salt exchanges across the aquifer‐ocean interface
Here we present clumped isotope Δ47 data of cave analogous experiments. We investigate the evolution of the Δ47 values of both the dissolved inorganic carbon (DIC) and the CaCO3 of thin-films flowing ...down in channels along inclined marble and glass plates precipitating CaCO3 along the flow path. With increasing distance of flow and residence time on the plate, we observe large deviations from the initial Δ47 values, along with increasingly over-estimated apparent Δ47- temperatures derived from the precipitated CaCO3. With further increasing residence time on the plates (>250 s) and decreasing supersaturation with respect to calcite, the CaCO3 Δ47 values start to approach the initial equilibrium values again. This highlights the potentially strong effect of disequilibrium isotope effects on clumped isotope temperatures derived from speleothems, in particular because the disequilibrium effect on the Δ47 values is most pronounced in the first few 100 seconds of CaCO3 precipitation.
The experimental Δ47 values are consistent with a recent modeling study by Guo and Zhou (2019). The maximum degree of disequilibrium, however, seems to be more pronounced than predicted by the model for some of the experiments. A potential reason for this observation is that suitable kinetic fractionation factors are so far not available. While the Δ47 values of the CaCO3 decrease along the plate as the model suggests for the Δ47 values of the HCO3−, those of the DIC increase and follow the modelled Δ47 values of the dissolved CO2.
Based on our study, we can neither confirm nor exclude a temperature dependence of the Δ47-δ18O slope as well as a dependence on cave pCO2, which highlights the complexity of this relationship. In addition, the non-linear evolution of Δ47 and δ18O values with time and along the flow path restricts a correction of the Δ47 and δ18O values based on the Δ47-δ18O slope to the initial phase of the isotope evolution. So far, a correction of the kinetic isotope effects is not yet possible, but this might be important in future studies if the disequilibrium slope on a Δ47-δ18O diagram could be precisely determined for the initial phase of isotope evolution.
In the past, laboratory experiments and theoretical calculations showed a mismatch in the derived sticking properties of silicates in the context of planetesimal formation. It has been proposed by ...Kimura et al. that this mismatch is due to the value of the surface energy assumed, supposedly correlated to the presence or lack of water layers of different thickness on a grain's surface. We present tensile strength measurements of dust aggregates with different water content here. The results are in support of the suggestion by Kimura et al. Dry samples show increased strengths by a factor of up to 10 over wet samples. A high value of γ = 0.2 J m−2 likely applies to the dry low pressure conditions of protoplanetary disks and should be used in the future.
Avoiding overhead aversion in charity Gneezy, Uri; Keenan, Elizabeth A.; Gneezy, Ayelet
Science (American Association for the Advancement of Science),
10/2014, Letnik:
346, Številka:
6209
Journal Article
Recenzirano
Donors tend to avoid charities that dedicate a high percentage of expenses to administrative and fundraising costs, limiting the ability of nonprofits to be effective. We propose a solution to this ...problem: Use donations from major philanthropists to cover overhead expenses and offer potential donors an overhead-free donation opportunity. A laboratory experiment testing this solution confirms that donations decrease when overhead increases, but only when donors pay for overhead themselves. In a field experiment with 40,000 potential donors, we compared the overhead-free solution with other common uses of initial donations. Consistent with prior research, informing donors that seed money has already been raised increases donations, as does a $1:$1 matching campaign. Our main result, however, clearly shows that informing potential donors that overhead costs are covered by an initial donation significantly increases the donation rate by 80% (or 94%) and total donations by 75% (or 89%) compared with the seed (or matching) approach.
Machine Learning Predicts Laboratory Earthquakes Rouet‐Leduc, Bertrand; Hulbert, Claudia; Lubbers, Nicholas ...
Geophysical research letters,
28 September 2017, Letnik:
44, Številka:
18
Journal Article
Recenzirano
Odprti dostop
We apply machine learning to data sets from shear laboratory experiments, with the goal of identifying hidden signals that precede earthquakes. Here we show that by listening to the acoustic signal ...emitted by a laboratory fault, machine learning can predict the time remaining before it fails with great accuracy. These predictions are based solely on the instantaneous physical characteristics of the acoustical signal and do not make use of its history. Surprisingly, machine learning identifies a signal emitted from the fault zone previously thought to be low‐amplitude noise that enables failure forecasting throughout the laboratory quake cycle. We infer that this signal originates from continuous grain motions of the fault gouge as the fault blocks displace. We posit that applying this approach to continuous seismic data may lead to significant advances in identifying currently unknown signals, in providing new insights into fault physics, and in placing bounds on fault failure times.
Plain Language Summary
Predicting the timing and magnitude of an earthquake is a fundamental goal of geoscientists. In a laboratory setting, we show we can predict “labquakes” by applying new developments in machine learning (ML), which exploits computer programs that expand and revise themselves based on new data. We use ML to identify telltale sounds—much like a squeaky door—that predict when a quake will occur. The experiment closely mimics Earth faulting, so the same approach may work in predicting timing, but not size, of an earthquake. This approach could be applied to predict avalanches, landslides, failure of machine parts, and more.
Key Points
Machine learning appears to discern the frictional state when applied to laboratory seismic data recorded during a shear experiment
Machine learning uses statistical characteristics of the recorded seismic signal to accurately predict slip failure time
We posit that similar machine learning approaches applied to geophysical data in Earth will provide insight in fault frictional processes
The Coriolis effect plays an important role in the generation and dissipation of internal tides. In this study, the effects of the Coriolis parameter on internal tides generated by tidal current ...flowing over rough subsurface topography were investigated in the laboratory. The results show that the variation in the internal tidal local dissipation rate with variation in the Coriolis parameter in the deep layer follows a Gaussian distribution. The strongest dissipation occurs near the critical latitude where the local Coriolis parameter is half of the tidal frequency. A modified internal tidal mixing parameterization was developed by introducing a correction function related to the Coriolis effect on internal tidal local dissipation in the deep ocean, based on the original version developed by St. Laurent et al. (2002). The new parameterization was then implemented in a parallel ocean model. The results indicate that the deep global meridional overturning circulation (GMOC) is strengthened in the low and middle latitudes and the Southern Ocean by the change, compared with the original parameterization.
When voting rights are extended, people pay attention to the behavior of new voters. However, the reactions of existing voters are also crucial for voting outcomes after enfranchisement. This study ...conducts a laboratory experiment to compare the effects of extending voting rights to minorities who did not initially have the right to vote and granting proxy votes to the existing majority who vote on behalf of the minorities. We observe that enfranchising excluded minorities increases the proportion of votes in favor of minorities. However, the realized proportion is not as large as expected. Proxy voting does not increase this proportion. Behind such aggregate outcomes, some existing majorities alter their vote choices to protect their payoffs in response to changes in voting rules. Electoral reforms that do not consider such a response but rely on the altruism of the existing majority are unlikely to succeed in reflecting minorities’ interests.
In this paper we contribute to the discussion on whether intellectual property rights foster or hinder innovation by means of a laboratory experiment. We introduce a novel Scrabble-like word-creation ...task that captures most essentialities of a sequential innovation process. We use this task to investigate the effects of intellectual property allowing subjects to impose license fees on their innovations. We find intellectual property to have an adverse effect on welfare as innovations become less frequent and less sophisticated. Introducing communication among innovators does not reduce this detrimental effect. Introducing intellectual property results in more basic innovations, with subjects failing to exploit the most valuable sequential innovation paths. Subjects act more self-reliant and non-optimally in order to avoid paying license fees. Our results suggest that granting intellectual property rights hinders innovation, especially for sectors characterized by a strong sequentiality in innovation processe. (web URL: http://www.sciencedirect.com/science/article/pii/S0048733316301159)
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