11,006 research outputs found
Updated Conservation Status of Protected Minnesota Caddisflies
Seven of the 13 Minnesota Trichoptera species with official protected status were located in the state during 1997-2001, including four species â Agapetus tomus, Asynarchus rossi, Hydroptila novicola, and Polycentropus milaca â not collected in nearly 40 years. Three species â Chilostigma itascae, Oxyethira ecornuta, and Polycentropus milaca â appear rare in Minnesota, two â Agapetus tomus and Asynarchus rossi â appear rare but locally abundant, and two â Hydroptila novicola and Oxyethira itascae â were found throughout northern Minnesota suggesting that they are more abundant than previously thought. Five listed species were not collected during this study and are currently of unknown conservation status. One listed species, Setodes guttatus, almost certainly does not occur in Minnesota and should be delisted
Dynamic Regulation Design Without Payments: Timing is Everything
We consider a two period model of optimal regulation of a ïŹrm subject to marginal compliance cost shocks. The regulator faces an asymmetric information problem: the ïŹrm knows current compliance costs, but the regulator does not. Both the regulator and the ïŹrm are uncertain about future costs. In our basic framework, the regulator may not oïŹer payments to the ïŹrm; we show that the regulator can vary the strength of regulation over time to induce the ïŹrm to reveal its costs and increase welfare. In the optimal mechanism, the regulator oïŹers stronger (weaker) regulation in the ïŹrst period and weaker (stronger) regulation in the second period if the ïŹrm reports low (high) compliance costs in the ïŹrst period. Low cost ïŹrms expect compliance costs to rise in the future, and thus prefer weaker regulation in the second period. High cost ïŹrms expect costs to fall in the future and thus prefer regulation which becomes more strict over time. Thus the regulator oïŹers the low (high) cost ïŹrms slightly weaker (stronger) regulation in the second period in exchange for much stronger (weaker) regulation in the ïŹrst period. We refer to our dynamic mechanism as âtimingâ the regulation. If the regulator can make payments, then the optimal mechanism to some degree times the regulation as long as a positive cost of funds exists. If the cost of funds is high enough, then under the optimal mechanism the regulator will not use payments and only use our timing mechanismregulation design, environmental regulation design, hybrid policies, dynamic contracts.
Regulation and deregulation in industrial countries : some lessons for LDCs
The United States'experience with antitrust and with directive regulation in the rail, trucking, airline, and telephone sectors offers useful lessons for developing countries. The experience highlights the realities both of market failure and of the difficulties of implementing regulation to control it - and reveals that imperfect regulation may be no better than imperfect competition. Antitrust measures to regulate price fixing and to require approval for mergers above some threshold level of industrial concentration are straightforward to implement and have provided some gains in economic welfare. The regulation of price discrimination, restrictive vertical practices, and predatory pricing is administratively more difficult, and the potential gains are less clearly evident. In many situations, import competition can be an efficient alternative. Direct regulation of rail, trucking, airline, and telephone was frequently inefficient, the regulatory apparatus often lost sight of its original objectives, and the regulators were captured by the regulated. For rail and trucking regulation, the regulatory outcome probably was worse than it would have been under laissez-faire.Administrative&Regulatory Law,Economic Theory&Research,National Governance,Knowledge Economy,Environmental Economics&Policies
Ultrafaint Dwarfs - Star Formation and Chemical Evolution in the Smallest Galaxies
In earlier work we showed that a dark matter halo with a virial mass of
M can retain a large percentage of its baryons in the face of
the pre-ionization phase and supernova explosion from a 25 star. Here
we expand on the results of that work, investigating the star formation and
chemical evolution of the system beyond the first supernova. In a galaxy with a
mass M, sufficient gas is retained by the potential for
a second period of star formation to occur. The impact of a central explosion
is found to be much stronger than that of an off-centred explosion both in
blowing out the gas and in enriching it, as in the off-centered case most of
the supernova energy and metals escape into the IGM. We model the star
formation and metallicity given the assumption that stars form for 100, 200,
400 and 600 Myr and discuss the results in the context of recent observations
of very low mass galaxies. We show that we can account for most features of the
observed relationship between [/Fe] and [Fe/H] in ultra-faint dwarf
galaxies with the assumption that the systems formed at a low mass, rather than
being remnants of much larger systems
Associations between Feeling and Judging the Emotions of Happiness and Fear: Findings from a Large-Scale Field Experiment
Background:
How do we recognize emotions from other people? One possibility is that our own emotional experiences guide us in the online recognition of emotion in others. A distinct but related possibility is that emotion experience helps us to learn how to recognize emotions in childhood.
Methodology/Principal Findings:
We explored these ideas in a large sample of people (N = 4,608) ranging from 5 to over 50 years old. Participants were asked to rate the intensity of emotional experience in their own lives, as well as to perform a task of facial emotion recognition. Those who reported more intense experience of fear and happiness were significantly more accurate (closer to prototypical) in recognizing facial expressions of fear and happiness, respectively, and intense experience of fear was associated also with more accurate recognition of surprised and happy facial expressions. The associations held across all age groups.
Conclusions:
These results suggest that the intensity of one's own emotional experience of fear and happiness correlates with the ability to recognize these emotions in others, and demonstrate such an association as early as age 5
Ultrafaint Dwarf Galaxies - the lowest mass relics from before reionization
New observations indicate that ultrafaint dwarf galaxies (UFD) -- the least
luminous systems bound by dark matter halos (<10^5 Lsun) -- may have formed
before reionization. The extrapolated virial masses today are uncertain with
estimates ranging from 10^8 Msun to 10^9 Msun. We show that the progenitor halo
masses of UFDs can be as low as Mvir = 10^7 Msun. Under the right conditions,
such a halo can survive the energy input of a supernova and its radiative
progenitor. A clumpy medium is much less susceptible to both internal and
external injections of energy. It is less prone to SN sweeping because the
coupling efficiency of the explosive energy is much lower than for a diffuse
ISM. With the aid of the 3D hydro/ionization code Fyris, we show that
sufficient baryons are retained to form stars following a single supernova
event in dark matter halos down to Mvir ~ 10^7 Msun with radiative cooling. The
gas survives the SN explosion, is enriched with the abundance yields of the
discrete events, and reaches surface densities where low mass stars can form.
Our highest resolution simulations reveal why cooling is so effective in
retaining gas compared to any other factor. In the early stages, the super-hot
metal-enriched SN ejecta exhibit strong cooling, leading to much of the
explosive energy being lost. Consistent with earlier work, the baryons do *not*
survive in smooth or adiabatic models in the event of a supernova. The smallest
galaxies carry signatures of the earliest epochs of star formation, which may
distinguish a small primordial galaxy from one that was stripped down to its
present size through tidal interaction. We discuss these results in the context
of local UFDs and damped Ly-alpha systems (z~2) at very low metallicity ([Fe/H]
~ -3). We show that both classes of objects are consistent with primordial
low-mass systems that have experienced only a few enrichment events.Comment: 32 pages, 25 figures, accepted by Ap
Supply Function Equilibria: Step Functions and Continuous Representations
In most wholesale electricity markets generators must submit step-function offers of supply to a uniform price auction, and the market is cleared at the price of the most expensive offer needed to meet realised demand. Such markets can most elegantly be modelled as the pure-strategy, Nash Equilibrium of continuous supply functions, in which each supplier has a unique profit maximising choice of supply function given the choices of other suppliers. Critics argue that the discreteness and discontinuity of the required steps can rule out pure-strategy equilibria and may result in price instability. This paper argues that if prices must be selected from a finite set the resulting step function converges to the continuous supply function as the number of steps increases, reconciling the apparently very disparate approaches to modelling electricity markets.Auctions; Supply Function Equilibria; Convergence of Step-Functions; Electricity Markets
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