Optimal reproductive allocation in annuals and an informational constraint on plasticity

In this computational study, we examined optimal reproductive allocation schedules in annual plants whose season lengths vary in predictability. We discuss relationships among season-length predictability, the form of the optimal allocation schedule, the degree of plasticity reflected in the optimal reaction norm, and the competitive consequences of plasticity and bet-hedging. We used an evolutionary algorithm to search the allocation-schedule space for optima, given different distributions of season length. The resulting schedules maximize geometric-mean fecundity under their selecting distributions. We then examined the relative fitness of these schedules in simulated competition among reaction norms optimized for different degrees of season-length predictability. Gradedness of optimal schedules decreases with increasing season-length predictability, and reaction norms comprising highly graded schedules reflect lesser plasticity than norms comprising schedules that are less graded. In simulations, competitively successful genotypes were those that reflected plasticity appropriate to the season-length predictability. Informational constraints in the form of low season-length predictability select for low plasticity and high bet-hedging in allocation. Because an environmental cue must mediate the relationship between environment and fitness, plasticity in reproductive allocation ought to be understood not as a direct response to the selective environment, but rather to cues that are correlated with relevant environmental parameters.     

Pathological gambling severity is associated with impulsivity in a delay discounting procedure

Research and clinical expertise indicates that impulsivity is an underlying feature of pathological gambling. This study examined the extent to which impulsive behavior, defined by the rate of discounting delayed monetary rewards, varies with pathological gambling severity, assessed by the South Oaks Gambling Screen (SOGS). Sixty-two pathological gamblers completed a delay discounting task, the SOGS, the Eysenck impulsivity scale, the Addiction Severity Index (ASI), and questions about gambling and substance use at intake to outpatient treatment for pathological gambling. In the delay discounting task, participants chose between a large delayed reward (US $1000) and smaller more immediate rewards (US $1-$999) across a range of delays (6h to 25 years). The rate at which the delayed reward was discounted (k value) was derived for each participant and linear regression was used to identify the variables that predicted k values. Age, gender, years of education, substance abuse treatment history, and cigarette smoking history failed to significantly predict k values. Scores on the Eysenck impulsivity scale and the SOGS both accounted for a significant proportion of the variance in k values. The predictive value of the SOGS was 1.4 times that of the Eysenck scale. These results indicate that of the measures tested, gambling severity was the best single predictor of impulsive behavior in a delay discounting task in this sample of pathological gamblers.     

Measuring state changes in human delay discounting: an experiential discounting task

A new experiential discounting task (EDT) is presented. Unlike existing question-based measures of delay discounting, which rely on imagined consequences during task completion, this EDT requires that participants experience choice consequences (i.e. delays and pseudo consumatory responses) during the measurement period. As a preliminary examination of this task's sensitivity to variability in discounting, 12 participants (six females) completed a timing test (production and reproduction), a question-based measure of delay discounting, and the EDT during non-sleep-deprived (awake 7 h) and sleep-deprived (awake 21 h) conditions. Based on evidence that sleep deprivation increases impulsive behavior, it was hypothesized that participants would underrepresent time intervals in both production and reproduction procedures and discount significantly more with the discounting procedures while sleep deprived. Unfortunately, data from the question-based discounting procedure could not be reported due to invalid task completion. However, as hypothesized, certain production and reproduction intervals were underrepresented on the timing test, and discounting was significantly steeper on the EDT when participants were sleep deprived. Also, rate of discounting on the EDT was better characterized by a hyperbolic function than by exponential function, which is consistent with previous delay-discounting research. These preliminary results suggest this EDT may be a useful measure for assessing state changes in discounting processes.     

Ovule discounting in an outcrossing, cryptically dioecious tree

Ovule discounting denotes the reduction in the number of ovules available for cross-fertilization due to the interference of inferior pollen. Traditionally, ovule discounting has been discussed solely from the perspective of compromised outcrossing opportunities as a result of selfing, but the principle is more general. Here, we extend its applicability beyond the simple contrast between selfing and outcrossing by showing that, in the cryptically dioecious tree species Fraxinus ornus, ovule discounting through frequent outcrossing with inferior fathers also constitutes a substantial cost of mating. In F. ornus, hermaphrodites produce pollen capable of siring offspring, but these offspring are less viable than those sired by males and are inferred to produce few, if any, surviving progeny. In this paper, we used microsatellite markers to analyze the mating system and paternity in a wild population of F. ornus. We found that the effective number of sires per mother was low (N(ep) = 2.93 to 4.95), and that paternity was correlated among progeny sampled from the same mother, but not among progeny sampled from neighboring mothers. Despite the existence of a local spatial genetic structure (up to 30 m), we found no evidence of biparental inbreeding. There was negligible selfing by hermaphrodites, but they sired approximately one fourth of the seeds produced by other hermaphrodites. Given that these progeny are not inferred to reach reproductive maturity, this constitutes a substantial cost of ovule discounting in the broad sense. We discuss the possible reasons for why hermaphrodites invest resources into inferior pollen.     

Self-control and unhealthy body weight: The role of impulsivity and restraint

We examine the relationship between trait self-control and body weight. Data from a population representative household survey reveal that limited self-control is strongly associated with both unhealthy body weight and poorer subjective weight-related well-being. Those with limited self-control are characterized by reduced exercising, repeated dieting, unhealthier eating habits, and poorer nutrition. We propose an empirical method to isolate two facets of self-control limitations—high impulsivity and low restraint. Each has differential predictive power. Physical activity, dieting, and overall body weight are more strongly associated with restraint; impulsivity is relatively more predictive of when, where, and what people eat.     

Intertemporal discounting as a risk factor for high BMI: Evidence from Australia, 2008

This paper explores the relationship between intertemporal discounting and body weight, using stated preference measures of intertemporal discounting, and the body mass index (BMI) to represent relative body weight. The empirical analysis uses Australian data obtained in 2008 through the South Australian Health Omnibus Survey. A quantile regression analysis is used to allow the marginal effects of the explanatory variables on BMI to vary across the conditional BMI distribution. It is shown that an indicator of intertemporal discounting elicited from a hypothetical monetary trade-off has a significant positive relationship with BMI. This relationship appears to be stronger in the upper quantiles, but there is insufficient statistical evidence for this difference. Evidence is presented that intertemporal discounting is a risk factor for increased BMI with a magnitude of effect comparable to more commonly recognized risk factors such as income and education. However there is no significant relationship found between BMI and an alternative indicator of intertemporal discounting elicited from trade-offs in health status.     

Circadian preference and the big five: the role of impulsivity and sensation seeking

In the present study, the relationship between personality dimensions and Circadian Preference was evaluated using a structural equation modeling approach. Participants (N?=?390; 53.8% female, mean age: 26.8?±?8.1 yrs) completed measures of Circadian Preference, Impulsivity, Sensation Seeking, and the Big Five factors. A mediation structural equation model assessed the direct and indirect effects of the Big Five factors on Circadian Preference. The results showed that Impulsivity and Sensation Seeking were significantly associated with Eveningness, whereas no significant direct effects of the Big Five traits were detected once the effects of Impulsivity and Sensation Seeking were taken into account. (Author correspondence: p.russo@unibo.it ).     

Valuation, appraisal, discounting, obsolescence and depreciation

Previous editions of this Journal have drawn attention to the critical role valuation plays in life cycle analysis and environmental impact assessment (see for exampleVolkwkin andKlöpffer |1|). In particular, the critical role of valuation has heen highlighed in a number of discussions on ‘valuation step’ within life cycle costing, ‘hedonic and contingency’ assessments of environmental impact and both the utility and welfare of ‘pathway’ analysis/assessment (Krkwitt, Mayerhofer, Trukenmüller andFriedrich, 1998;Powell, Pearce andCraighill, 1997;Volkwein, On in andKlöpffer, 1996 |2-4|). Focusing on the utility of market valuation, this paper examines the critique of discounting environmentalists have made in relation to property valuation, investment appraisal and the application of the principle in the income based net annual return model of land use time-horizons and the spatial configuration of building programmes-a criticism implict in ‘valuation step’, ‘hedonic, contingency’ and ‘pathway’ analysis/assessments. It examines the argument put forward regarding the link between the selection of a discount rate, the valuation of property, appraisal of investment and inter-generational downloading of costs associated with the use of land, repair, maintenance and refurbishment of buildings: the downloading of costs, seen by some, to have an adverse impact and work against the introduction of experimental designs aimed at energy saving, clean air environments.     

Geometric service life modelling and discounting,a practical method for parametrised life cycle assessment

Purpose

To evaluate the long-term advantage of reusing building elements, including reduced material consumption and waste production, life cycle assessments are purposeful. To translate these assessments in relevant design advices, it is necessary to model accurately the service life of the considered elements and acknowledge the related uncertainties. Practical methods to do this are nevertheless lacking. In reaction, this paper proposes a new assessment method: geometric service life modelling and discounting.

Methods

The developed method is extensively parametric. Its formulas express an element’s service life in terms of a limited number of variables. This facilitates the evaluation of large series of elements as well as the automation of uncertainty analyses. Further, the method tackles different modelling complexities such as the interaction between replacements and refurbishments. Taking into account these complexities aligns the assessments with realistic service lives. For the presentation of the developed method, a focus on life cycle costing is chosen.

Results and discussion

In this paper, the outcomes of the newly developed method are compared to those of an existing calculation method and benchmarked with the manual modelling and assessment of 390 simplified building elements. This comparison is based on three indicators characterising the methods’ accuracy: the number of interventions, their individual impact and their resulting net present value. For each indicator, geometric discounting led to a considerable increase of accuracy compared to the existing method.

Conclusions

From this comparison, it is concluded that geometric service life modelling and discounting offers not only a well-defined procedure for parametrised life cycle assessment studies, this method is also more accurate than the existing one. Moreover, the uncertainty analyses it facilitates illustrate how detailed assessment outcomes and relevant design advices about the effectiveness of element reuse can be obtained. Nevertheless, further research about the method’s practical implementation is required.

     

Time discounting,present biases,and health-related behaviors: Evidence from Japan

Human health is considered the outcome of intertemporal choices under tradeoffs between a small immediate reward and a larger delayed reward. Health-related behaviors are thus affected by personal time preferences. Based on an Internet-based survey conducted on Japanese adults, we contribute to the literature by incorporating the multifaceted nature of time discounting in an analysis of the associations between time preference and health-related behaviors. We find that, first, less patient respondents tend to exhibit worse health-related attributes. Second, present bias, which is measured by the degree of declining impatience, is positively associated with unhealthy behaviors for naïve respondents, who are unaware of their self-control problem. Third, such associations cannot be found in sophisticates, who are aware of that. As a policy implication, direct intervention policies, including “nudging,” are more effective than a commitment device provision in correcting the unhealthy behaviors due to present bias. Fourth, the sign effect, wherein future losses are discounted at a lower rate than future gains, is negatively associated with unhealthy outcomes, although at weak statistical significance levels.     

Essential fatty acids and their role in the treatment of impulsivity disorders

Essential fatty acids (EFAs) have been shown to benefit patients with depression, schizophrenia and dementia. More recently, their role in disorders characterised by impulsivity has attracted some attention. The psychiatric conditions of attention-deficit hyperactivity disorder and borderline personality disorder as well as the phenomena of deliberate self-harm and violence have been ameliorated by the supplementation of EFAs in a number of recent clinical trials. This paper summarises the burgeoning clinical and basic research indicating the existence of significant deficits of EFAs in impulsivity disorders and the supplementation studies of EFAs in these diverse conditions, all of which remain a major therapeutic challenge.     

The source of a movement: making the case for social media as an informational source using Black Lives Matter

Social media is growing as a technological and social phenomenon, with billions of people using it every day around the world. Given its increasing ubiquity, researchers continue to seek to understand social media and its implications for the social world. Part of the growing body of scholarship on social media includes uncovering the most effective methodologies for exploration that appropriately consider differences between the technology of social media and the ways in which people use them. New directions for social media research include the use of big data and analysing the socio-technical nature of social media. Using data from an ongoing study on college Millennials that includes questions about their thoughts on the Black Lives Matter movement, the author suggests another direction for future research: studying the implications of social media as an informational source.     

Individual and social discounting in a viscous population

Social discounting in economics involves applying a diminishing weight to community-wide benefits or costs into the future. It impacts on public policy decisions involving future positive or negative effects, but there is no consensus on the correct basis for determining the social discount rate. This study presents an evolutionary biological framework for social discounting. How an organism should value future benefits to its local community is governed by the extent to which members of the community in the future are likely to be its kin. Trade-offs between immediate and delayed benefits to an individual or to its community are analysed for a modelled patch-structured iteroparous population with limited dispersal. It is shown that the social discount rate is generally lower than the individual (private) discount rate. The difference in the two rates is most pronounced, in ratio terms, when the dispersal level is low and the hazard rate for patch destruction is much smaller than the individual mortality rate. When decisions involve enforced collective action rather than individuals acting independently, social investment increases but the social discount rate remains the same.     

Characterization and mapping of an informational suppressor in Aspergillus nidulans

The present work was undertaken to characterize a suppressor gene present in a mutant strain of A. nidulans obtained with NTG (N-Methyl-N'-Nitro-N-Nitrosoguanidine). Analyses of this mutant have shown that this suppressor, designated suO1, induces phenotypic co-reversion of several auxotrophic mutations and makes the strain sensitive to aminoglycoside antibiotics and lower temperatures. suO1 has shown to be on linkage group VIII. The vegetative growth of the mutant strain is very unstable because the suppressor gene induces the production of prototrophic mitotic sectors. The strains bearing the suO1 gene produce cleistothecia containing a reduced number of viable ascospores during the sexual cycle. The segregation of the genetic markers has also been observed in the mutant strain self crossed. From the above results it may be concluded that suO1 is an informational suppressor.     

Enzymes and theoretical biology: sketch of an informational perspective of the cell.

In the theoretical scenarios of biology, new insights can be gained by the introduction of information-processing and artificial intelligence concepts, helping to organize the explanation of the many intra- and inter-cellular phenomena that molecular biology is accumulating. Enzymes contain some of the immediate clues; the whole informational processing of prokaryotic cells is another central subject of search. Additionally, prolonging the informational perspective of the cell, a significant parallel can be drawn between informational processes in biological, social and artificial intelligence systems. A more tangible definition of biological complexity and biological intelligence emerges.     

Successful treatment of an adult with symptomatic attention deficit,hyperactivity, and impulsivity after temporal lobe resection: case report

Attention deficit hyperactivity disorder (ADHD) is defined by inattentiveness, impulsivity, and/or hyperactivity and mandatorily requires an onset in childhood. Structural or functional anatomical abnormalities have mostly been found in the prefrontal cortex, the corpus callosum, the striatum, and the cerebellum. We here present the case of an adult woman who developed severe symptoms analogous to ADHD after right temporal lobectomy. Surgery had been necessary because of a large temporobasal arterio-venous malformation (AVM). The patient’s childhood and personal history before surgery had been without any indication of ADHD or any other mental disorder. Because of her distinct and impairing symptoms of ADHD, we initiated off-label methylphenidate treatment, achieving strong reduction in the symptoms. This proves further similarity of her symptomatic disorder to ADHD and supports a role of the right temporal lobe in ADHD.