Surface swimming behavior of the curculionid Ochetina uniformis Pascoe (Erirhininae, Stenopelmini) and Ludovix fasciatus (Gyllenhal) (Curculioninae, Erodiscini)

The swimming behavior exhibited by specimens of L. fasciatus and O. uniformis was analyzed frame-by-frame with video observation recorded with a digital camera, attached to a stereomicroscope. Adults of O. uniformis, an aquatic insect, swim with all three pairs of legs. During the process of swimming the majority of the abdomen and rostrum remain submerged, part of the fore and hind tibiae remain above the surface, while the mid tibiae remain submerged. The mesothoracic legs, during the power-stroke stage, provide the greatest thrust while the metathoracic legs provide the least forward propulsion. The prothoracic legs, extended forward, help to direct the swimming. The semi-aquatic specie L. fasciatus shows the same swimming style as O. uniformis, that is, with movement of all the three pairs of legs; the mesothoracic legs are responsible for the main propulsion. The insect body remains on the water surface during the process of swimming, while the legs remain submerged. Both species complete a swimming cycle in 0.33 and 0.32 seconds, respectively, with an average speed of 1.38 cm/s and a maximum and minimum swimming duration time of 11.15 and 5.05 minutes, respectively, for L. fasciatus. The swimming behavior exhibited by O. uniformis and L. fasciatus corresponds to the style known as a breast strokelike maneuver. This is the first record of this kind of swimming for both species here observed and increases to seven the number of genera of Curculionidae exhibiting this behavior.

A dynamic choice model of hybrid behavior in the attribute-space

This paper presents a dynamic choice model in the attributespace considering rational consumers that discount the future. In lightof the evidence of several state-dependence patterns, the model isfurther extended by considering a utility function that allows for thedifferent types of behavior described in the literature: pure inertia,pure variety seeking and hybrid. The model presents a stationaryconsumption pattern that can be inertial, where the consumer only buysone product, or a variety-seeking one, where the consumer buys severalproducts simultane-ously. Under the inverted-U marginal utilityassumption, the consumer behaves inertial among the existing brands forseveral periods, and eventually, once the stationary levels areapproached, the consumer turns to a variety-seeking behavior. An empiricalanalysis is run using a scanner database for fabric softener andsignificant evidence of hybrid behavior for most attributes is found,which supports the functional form considered in the theory.

Strategic behavior and price discovery

The paper analyzes the effects of strategic behavior by an insider in a price discovery process, akin to an information tatonnement, in the presence of a competitive informed sector. Such processes are used in the preopening period of continuous trading systems in several exchanges. It is found that the insider manipulates the market using a contrarian strategy in order to neutralize the effect of the trades of competitive informed agents. Furthermore, consistently with the empirical evidence available, we find that information revelation accelerates close to the opening, that the market price does not converge to the fundamental value no matter how many rounds the tatonnement has, and that the expected trading volume displays a U-shaped pattern. We also find that a market with a larger competitive sector (smaller insider) has an improved informational efficiency and an increased trading volume. The insider provides a public good (a lower informativeness of the price) for the competitive informed sector.

Audit report on the Westory Fire Agency for the year ended June 30, 2007

Audit report on the Westory Fire Agency for the year ended June 30, 2007

A 15-year post evaluation of the fire effects on ant community in an area of Amazonian forest

Fire represents an important disturbance to ant communities in areas of fire regime. Otherwise, little is known about the effects of fire on ant communities in areas of non-fire regimes, such as in the Amazonian region. We evaluated the long-term effect of fire on ant species richness in a rain forest (Bacaba Plateau) burned 15-years ago and compare our data with the data of primary unburned forest. A total of 85 ant species distributed in 21 genera and 14 tribes were collected; among them, 72 and 44 species were found on the litter and vegetation, respectively. The fire damaged forest studied supports an intermediate richness of ants when compared to a primary unburned rain forest in the same region. A comparative analysis of ant species richness showed that the Bacaba Plateau presented a different ant fauna when compared with the primary unburned forests, suggesting that fire can alter ant species composition. Although, our results cannot be conclusive on the effects of fire on ant community, they represent a pioneer data on human induced fire in tropical rain forests.

Evolution at Two Levels in Fire Ants: The Relationship between Patterns of Gene Expression and Protein Sequence Evolution.

Variation in protein sequence and gene expression each contribute to phenotypic diversity, and may be subject to similar selective pressures. Eusocial insects are particularly useful for investigating the evolutionary link between protein sequence and condition-dependent patterns of gene expression because gene expression plays a central role in determining differences between eusocial insect sexes and castes. We investigated the relationship between protein coding sequence evolution and gene expression patterns in the fire ants Solenopsis invicta, S. richteri, and their hybrids to gain greater insight into how selection jointly operates on gene expression and coding sequence. We found that genes with high expression variability within castes and sexes were frequently differentially expressed between castes and sexes, as well as between species and hybrids. These results indicate that genes showing high variation in expression in one context also tend to show high variation in expression in other contexts. Our analyses further revealed that variation in both intra- and interspecific gene expression was positively associated with rate of protein sequence evolution in Solenopsis. This suggests that selective constraints on a gene operate both at the level of protein sequence and at the level of gene expression regulation. Overall, our study provides one of the strongest demonstrations that selective constraints mediate both protein sequence evolution and gene expression variability across different biological contexts and timescales.

Is confidence in decisions related to feedback? Evidence-and lack of evidence-from random samples of real-world managerial behavior?

Confidence in decision making is an important dimension of managerialbehavior. However, what is the relation between confidence, on the onehand, and the fact of receiving or expecting to receive feedback ondecisions taken, on the other hand? To explore this and related issuesin the context of everyday decision making, use was made of the ESM(Experience Sampling Method) to sample decisions taken by undergraduatesand business executives. For several days, participants received 4 or 5SMS messages daily (on their mobile telephones) at random moments at whichpoint they completed brief questionnaires about their current decisionmaking activities. Issues considered here include differences between thetypes of decisions faced by the two groups, their structure, feedback(received and expected), and confidence in decisions taken as well as inthe validity of feedback. No relation was found between confidence indecisions and whether participants received or expected to receivefeedback on those decisions. In addition, although participants areclearly aware that feedback can provide both confirming and disconfirming evidence, their ability to specify appropriatefeedback is imperfect. Finally, difficulties experienced inusing the ESM are discussed as are possibilities for further researchusing this methodology.

Revenue management under general discrete choice model of consumer behavior

Customer choice behavior, such as 'buy-up' and 'buy-down', is an importantphe-nomenon in a wide range of industries. Yet there are few models ormethodologies available to exploit this phenomenon within yield managementsystems. We make some progress on filling this void. Specifically, wedevelop a model of yield management in which the buyers' behavior ismodeled explicitly using a multi-nomial logit model of demand. Thecontrol problem is to decide which subset of fare classes to offer ateach point in time. The set of open fare classes then affects the purchaseprobabilities for each class. We formulate a dynamic program todetermine the optimal control policy and show that it reduces to a dynamicnested allocation policy. Thus, the optimal choice-based policy caneasily be implemented in reservation systems that use nested allocationcontrols. We also develop an estimation procedure for our model based onthe expectation-maximization (EM) method that jointly estimates arrivalrates and choice model parameters when no-purchase outcomes areunobservable. Numerical results show that this combined optimization-estimation approach may significantly improve revenue performancerelative to traditional leg-based models that do not account for choicebehavior.

Economic rationality and ethical behavior

This paper argues that economic rationality and ethical behavior cannotbe reduced one to the other, casting doubts on the validity of formulaslike 'profit is ethical' or 'ethics pays'. In order to express ethicaldilemmas as opposing economic interest with ethical concerns, we proposea model of rational behavior that combines these two irreducible dimensions in an open but not arbitrary manner. Behaviors that are neither ethicalnor profitable are considered irrational (non-arbitrariness). However,behaviors that are profitable but unethical, and behaviors that are ethicalbut not profitable, are all treated as rational (openness). Combiningethical concerns with economic interest, ethical business is in turn anoptimal form of rationality between venality and sacrifice.Because every one prefers to communicate that he acts ethically, ethicalbusiness remains ambiguous until some economic interest is actuallysacrificed. We argue however that ethical business has an interest indemonstrating its consistency between communication and behavior by atransparent attitude. On the other hand, venal behaviors must remainconfidential to hide the corresponding lack of consistency. Thisdiscursive approach based on transparency and confidentiality helpsto further distinguish between ethical and unethical business behaviors.

Occurrence, biology and behavior of Liogenys fuscus Blanchard (Insecta, Coleoptera, Scarabaeidae) in Aquidauana, Mato Grosso do Sul, Brazil

Due to the importance of some Pleurosticti Scarabaeidae as agricultural pests allied to information absence on the species that occur in Brazilian Central-West region, on studies occurrence, biology and behavior on this group of scarabs were conducted. Biology and behavioral studies started with Liogenys fuscus Blanchard, 1850 (Melolonthinae), a very common species and were developed in Aquidauana, Mato Grosso do Sul. Adult beetles were collected from light traps from February 2005 to January 2007, at the experimental farm of the Universidade Estadual de Mato Grosso do Sul in Aquidauana (UEMS). In the laboratory adults were placed in plastic containers with soil with sprouts of Brachiaria decumbens Stapf (Poaceae). Eggs were transferred to a climatized chamber at 26 ± 1º C with a 12hourlight, 12hour darkness photoperiod cycle. Adult flight activity occurred in August and in September to December from 06:00 pm to 06:00 am, with the largest number of individuals flying from 07:00 to 10:00 pm. Eggs measured 1 x 1.5 mm and were laid individually or in groups in soil chambers; eggs were initially white and became yellow near hatching. The embryonic period lasted 14.3 days; first, second and third instars lasted 28.5, 48.8, and 68.2 days, respectively. The prepupal period lasted 120.2 days and the prepupa stayed inactive in soil. The mean duration of pupal stage was 27.5 days and the mean longevity of adults was 23.6 days. In laboratory the calling behavior between males and females was observed; copulation lasted, in mean, 25 minutes.

An evaluation of the life-cycle effects of minimum pensions on retirement behavior

In this paper we explore the effects of the minimum pension program on welfare andretirement in Spain. This is done with a stylized life-cycle model which provides a convenient analytical characterization of optimal behavior. We use data from the Spanish Social Security to estimate the behavioral parameters of the model and then simulate the changes induced by the minimum pension in aggregate retirement patterns. The impact is substantial: there is threefold increase in retirement at 60 (the age of first entitlement) with respect to the economy without minimum pensions, and total early retirement (before or at 60) is almost 50% larger.

Rational reasoning or adaptive behavior? Evidence from two-person beauty contest games

Many experiments have shown that human subjects do not necessarily behave in line with game theoretic assumptions and solution concepts. The reasons for this non-conformity are multiple. In this paper we study the argument whether a deviation from game theory is because subjects are rational, but doubt that others are rational as well, compared to the argument that subjects, in general, are boundedly rational themselves. To distinguish these two hypotheses, we study behavior in repeated 2-person and many-person Beauty-Contest-Games which are strategically different from one another. We analyze four different treatments and observe that convergence toward equilibrium is driven by learning through the information about the other player s choice and adaptation rather than self-initiated rational reasoning.

A Hull and White formula for a general stochastic volatility jump-diffusion model with applications to the study of the short-time behavior of the implied volatility

In this paper, generalizing results in Alòs, León and Vives (2007b), we see that the dependence of jumps in the volatility under a jump-diffusion stochastic volatility model, has no effect on the short-time behaviour of the at-the-money implied volatility skew, although the corresponding Hull and White formula depends on the jumps. Towards this end, we use Malliavin calculus techniques for Lévy processes based on Løkka (2004), Petrou (2006), and Solé, Utzet and Vives (2007).

Imitation of succesful behavior in Cournot markets

In an experimental standard Cournot Oligopoly we test the importance ofmodels of behavior characterized by imitation of succesful behavior. Wefind that the players appear to the rather reluctant to imitate.