Theory commonly posits agents who care both for the level of public good provision and the extent to which they personally contribute to the cause. Simply put, agents feel “warm glow” from the ...donations they make. I discuss a lottery fundraiser conducted in the field devised to exogenously vary the incentive to give and identify the structural parameters of warm glow. Estimates suggest that for participants claiming warm glow as their primary motivation, its shape is increasing and concave. Nevertheless, welfare analysis suggests that warm glow is unlikely to be the only important factor in the decision to give.
Economic theory predicts that agents work harder if they believe in the mission of the organization. We conduct a real-effort experiment with workers whose mission preferences are known, randomly ...assigning them to organizations with clear missions to create both matches and mismatches. Our estimates suggest that matching is a strong motivator, especially compared to mismatches. Further, we find that performance pay increases effort, though mostly among mismatched workers who substitute pay for matching. Our results suggest the importance of defining a clear mission to an organization and highlight the significance of sorting, screening, and compensation policies.
How and why are educators using Instagram? Carpenter, Jeffrey P.; Morrison, Scott A.; Craft, Madeline ...
Teaching and teacher education,
11/2020, Letnik:
96
Journal Article
Recenzirano
Odprti dostop
Social media are commonplace in many educators’ lives, but their Instagram activities have received no prior attention in the empirical literature. We therefore created and disseminated a survey ...regarding educators’ Instagram use. Analyses of 841 responses suggested participants were generally intensive users of Instagram who engaged in the exchange of both professional knowledge and wisdom, as well as affective support. In addition to identifying benefits to Instagram use, some participants offered critiques of Instagram’s professional utility. We discuss the implications of these findings for educators’ work in a digital era and the future of research on educators’ social media activities.
•Akin to other popular social media, Instagram has attracted significant use by educators.•In an online survey, 841 educators described how and why they used Instagram.•Affinity space and teacherpreneurship concepts framed our investigation.•Participants reported intensive and multifaceted use of Instagram that provided multiple professional benefits.•Many participants mixed posting of personal and professional content on Instagram.
The Gulf of Lion, Northwestern Mediterranean Sea, is one of few oceanic regions where deep convection occurs. We investigate the restratification following a convection event using measurements from ...an ocean glider equipped with turbulence microstructure sensors. This unique combination of instruments provides a high‐resolution description of the mixed layer with regard to turbulence, stratification and chlorophyll. We observe a rapid restratification process that proceeds over a timescale of days to one week. We find that restratification exerts a leading order control on surface mixed layer turbulence variability, as abrupt changes in turbulence dissipation rates are associated with the formation of near‐surface stratification. The near‐surface formation of stratification occurs through both the diurnal variability in surface buoyancy fluxes and through lateral advective processes. We conclude that daily near‐surface processes that influence stratification control mixed layer turbulence levels, and thus the phytoplankton response in the critical transition period to spring bloom.
Plain Language Summary
During winter in the Gulf of Lion, Northwestern Mediterranean Sea, a unique alignment of ocean conditions allow strong winds to cool the ocean surface enough to cause mixing of the surface waters to great depths in a process known as deep convection. When this event ceases, the water column tends to restore its original configuration, with light waters above dense waters. We capture the onset of this process, known as restratification, in high‐resolution observational detail together with measurements of ocean turbulence levels, collected with an autonomous ocean vehicle. The onset of restratification after convection takes place on a timescale of days to one week, and strongly influences turbulence variations within the surface waters. We conclude that this restratification has two main contributors, the near‐surface stratification that forms due to the daily variation of surface buoyancy fluxes, and the lateral exchange of denser waters from the surroundings. With sufficient light and nutrients after convection, this near‐surface stratification together with the absence of turbulent mixing allow phytoplankton to grow.
Key Points
Autonomous glider‐based turbulence measurements have captured restratification in a deep convection region
The onset of restratification occurs rapidly, over a timescale of days to one week
Near‐surface restratification is a primary control on mixed layer turbulence and phytoplankton growth
Advances in offshore wind farm (OWF) technology have recently led to their construction in coastal waters that are deep enough to be seasonally stratified. As tidal currents move past the OWF ...foundation structures they generate a turbulent wake that will contribute to a mixing of the stratified water column. In this study we show that the mixing generated in this way may have a significant impact on the large-scale stratification of the German Bight region of the North Sea. This region is chosen as the focus of this study since the planning of OWFs is particularly widespread. Using a combination of idealised modelling and in situ measurements, we provide order-of-magnitude estimates of two important time scales that are key to understanding the impacts of OWFs: (i) a mixing time scale, describing how long a complete mixing of the stratification takes, and (ii) an advective time scale, quantifying for how long a water parcel is expected to undergo enhanced wind farm mixing. The results are especially sensitive to both the drag coefficient and type of foundation structure, as well as the evolution of the pycnocline under enhanced mixing conditions-both of which are not well known. With these limitations in mind, the results show that OWFs could impact the large-scale stratification, but only when they occupy extensive shelf regions. They are expected to have very little impact on large-scale stratification at the current capacity in the North Sea, but the impact could be significant in future large-scale development scenarios.
In the low‐energy mixing environment of the Arctic Ocean halocline, a unique mixing mechanism of temperature is present. It consists of the formation of small‐vertical‐scale (∼1 m) intrusive ...features, with temperature anomalies up to ∼0.1°C, that create mean‐square vertical temperature gradients that are orders of magnitude greater than the background. This finescale temperature structure results in enhanced heat fluxes in conditions of extremely weak turbulence and is responsible for an irreversible mixing of heat into cold halocline waters. The rates of thermal variance dissipation and heat transport are comparable to turbulent mechanisms in the Arctic Ocean, such as internal wave‐driven mixing and double diffusive convection. We propose that in conditions of low turbulence, and in the presence of lateral thermal variability, the temperature field displays a self‐regulating mechanism by which it is able to enhance its finescale structure to generate enhanced mixing, thus compensating for the lack of turbulent fluxes.
Plain Language Summary
Understanding the causes of the ongoing reductions in Arctic sea ice cover requires knowledge of the processes controlling ocean heat transport. The transport caused by ocean turbulence is particularly important since it provides a mechanism by which significant heat that is stored in the Arctic Ocean water column may cause ice melt. However, this turbulent transport is hindered by an extremely stable, near‐surface layer, the halocline, that acts to damp ocean turbulence. In this study, we describe observations made using an autonomous underwater glider of a process within the halocline that is able to transport heat while bypassing the generation of ocean turbulence. We argue that this transport mechanism is a result of the highly stable, low‐turbulence conditions in the halocline, and is thus able to partially self‐regulate the transport of heat in such a stable environment.
Key Points
Significant thermal variance from intrusive features is found in the Arctic halocline in conditions of laminar and very weak turbulence
Mixing of heat resulting from these features can be comparable to internal wave and diffusive convection‐driven sources
We propose that the thermal variance arises from lateral water mass variability, and is a response to the weakly turbulent conditions
Because costly punishment is not credible, subgame perfection suggests that punishment will not deter free riding, regardless of the size or structure of groups. However, experiments show that people ...will punish free riders, even at considerable cost. To examine the implications of agents who punish, we simulate an environment populated with behavioral strategies seen in the lab and use the simulation to develop hypotheses about why group size should matter when punishment is allowed. We test these hypotheses experimentally and examine whether the effect of group size is purely due to the number of group members or if information about other group members is what is important. We find that large groups contribute at rates no lower than small groups because punishment does not fall appreciably in large groups. However, hindrances to monitoring do reduce the provision of the public good.
Abstract
This study uses CTD and microstructure measurements of shear and temperature from 348 glider profiles to characterize turbulence and turbulent mixing in the southeastern Beaufort Sea, where ...turbulence observations are presently scarce. We find that turbulence is typically weak: the turbulent kinetic energy dissipation rate
ε
has a median value (with 95% confidence intervals in parentheses) of 2.3 2.2, 2.4 × 10
−11
W kg
−1
and is less than 1.0 × 10
−10
W kg
−1
in 68% of observations. Variability in
ε
spans five orders of magnitude, with indications that turbulence is bottom enhanced and modulated in time by the semidiurnal tide. Stratification is strong and frequently damps turbulence, inhibiting diapycnal mixing. Buoyancy Reynolds number estimates suggest that turbulent diapycnal mixing is unlikely in 93% of observations; however, a small number of strongly turbulent mixing events are disproportionately important in determining net buoyancy fluxes. The arithmetic mean diapycnal diffusivity of density is 4.5 2.3, 14 × 10
−6
m
2
s
−1
, three orders of magnitude larger than that expected from molecular diffusion. Vertical heat fluxes are modest at
O
(0.1) W m
−2
, of the same order of magnitude as those in the Canada Basin double-diffusive staircase, however, staircases are generally not observed. Despite significant heat present in the Pacific Water layer in the form of a warm-core mesoscale eddy and smaller,
O
(1) km, temperature anomalies, turbulent mixing was found to be too low to release this heat to shallower depths.
Fixed-wage workers comprise the bulk of the labor force and yet little is known about how they respond to changes in their wage. Given recent interest in theories of reciprocity and intrinsic ...motivation and their implications for effort provision, the neoclassical prediction seems less obvious today. To better understand the motivation of these workers, I estimate their labor supply using a real effort experiment. Two results stand out. First, no one theory seems to fit the pooled data. On average, people work considerably harder than the minimum but they do not respond to changes in the wage. Second, pooling the data is deceptive because there seem to be distinct types with differing responses to the wage. Most workers can be classified as reciprocal or intrinsically motivated and, indeed, these types respond as theory would predict: reciprocators return wage gifts with increased effort and extrinsic incentives crowd out motivation for intrinsic workers.
In three experiments we examine the extent to which strategic sophistication (i.e., inductive reasoning, iterative dominance and level-k thinking) is determined by broader cognitive skills. In the ...first experiment we replicate previous results showing strong associations between cognitive ability and sophistication in a game of iterative dominance and show that similar results arise in a game requiring induction. In the second two experiments we extend the literature in new directions. In Experiment 2 we modify the games to better capture participantsʼ ability to reason inductively and predict the sophistication of others and, again, find strong associations between cognitive ability, measured using a common IQ test, and sophistication. In Experiment 3 we examine more closely the causal nature of the relationship between cognitive ability and sophistication. We use a standard tool from cognitive psychology to randomly shock the cognitive ability of participants and show that this significantly affects game performance.
•In three experiments we examine the extent to which strategic sophistication is determined by broader cognitive skills.•In Experiment 1 we find strong associations between cognitive ability and sophistication in games requiring iterative dominance and backward induction.•In Experiment 2 we find similar associations in games modified to better capture participantsʼ ability to reason inductively and predict the sophistication of others.•In Experiment 3 we randomly lower the cognitive ability of some participants to identify the causal affect of ability on sophistication.
PDF
