Forward-looking versus recursive-dynamic modeling in climate policy analysis: A comparison

This paper develops a multi-regional general equilibrium model for climate policy analysis based on the latest version of the MIT Emissions Prediction and Policy Analysis (EPPA) model. We develop two versions so that we can solve the model either as a fully inter-temporal optimization problem (forward-looking, perfect foresight) or recursively. The standard EPPA model on which these models are based is solved recursively, and it is necessary to simplify some aspects of it to make inter-temporal solution possible. The forward-looking capability allows one to better address economic and policy issues such as borrowing and banking of GHG allowances, efficiency implications of environmental tax recycling, endogenous depletion of fossil resources, international capital flows, and optimal emissions abatement paths among others. To evaluate the solution approaches, we benchmark each version to the same macroeconomic path, and then compare the behavior of the two versions under a climate policy that restricts greenhouse gas emissions. We find that the energy sector and CO(2) price behavior are similar in both versions (in the recursive version of the model we force the inter-temporal theoretical efficiency result that abatement through time should be allocated such that the CO(2) price rises at the interest rate.) The main difference that arises is that the macroeconomic costs are substantially lower in the forward-looking version of the model, since it allows consumption shifting as an additional avenue of adjustment to the policy. On the other hand, the simplifications required for solving the model as an optimization problem, such as dropping the full vintaging of the capital stock and fewer explicit technological options, likely have effects on the results. Moreover, inter-temporal optimization with perfect foresight poorly represents the real economy where agents face high levels of uncertainty that likely lead to higher costs than if they knew the future with certainty. We conclude that while the forward-looking model has value for some problems, the recursive model produces similar behavior in the energy sector and provides greater flexibility in the details of the system that can be represented. (C) 2009 Elsevier B.V. All rights reserved.

Executive "brake failure" following deactivation of human frontal lobe

In the course of daily living, humans frequently encounter situations in which a motor activity, once initiated, becomes unnecessary or inappropriate. Under such circumstances, the ability to inhibit motor responses can be of vital importance. Although the nature of response inhibition has been studied in psychology for several decades, its neural basis remains unclear. Using transcranial magnetic stimulation, we found that temporary deactivation of the pars opercularis in the right inferior frontal gyrus selectively impairs the ability to stop an initiated action. Critically, deactivation of the same region did not affect the ability to execute responses, nor did it influence physiological arousal. These findings confirm and extend recent reports that the inferior frontal gyrus is vital for mediating response inhibition.

Urticaria unresponsive to antihistaminic treatment: An open study of therapeutic options based on histopathologic features

Background: The non- or low-sedating H1 receptor antagonists represent the basic therapy for urticaria. Objective: To test an alternative approach to patients unresponsive to conventional treatment. Materials and methods: A total of 22 patients with chronic urticaria unresponsive to conventional antihistamine treatment were enrolled for this study. They had uncontrolled urticaria even using multiple combinations of antihistamines on maximum doses and corticosteroids in short cycles (prednisone 20-40 mg, per os once a day, 3-7 days per month). Cutaneous biopsies of the urticaria lesions were taken. These findings were classified as: (I) a mixture of perivascular dermal inflammatory infiltrate composed of lymphocytes, monocytes and neutrophils and/or eosinophils; (II) inflammatory infiltrate composed chiefly of neutrophils; and (III) inflammatory infiltrate composed mainly of eosinophils. According to histology, the patients were submitted to one of the following therapeutic schemes: class A - antihistamine treatment plus dapsone; class B - colchicine or dapsone; class C montelukast. Results: Four patients in class A, 08 in class B and seven in class C displayed complete control of urticaria after 12 weeks of treatment; one patient in class B and two in class C did not respond to treatment. Two years after discontinuation, 16 patients are still free of urticaria. Conclusions: This study suggests an alternative approach for treating unresponsive chronic urticaria.

Performance on tests sensitive to impaired executive ability in schizophrenia, mania and well controls: acute and subacute phases

Aims: To compare the performance of schizophrenia, mania and well control groups on tests sensitive to impaired executive ability, and to assess the within-group stability of these measures across the acute and subacute phases of psychoses. Method: Recently admitted patients with schizophrenia (n=36), mania (n=18) and a well control group (n=20) were assessed on two occasions separated by 4 weeks. Tests included: the Controlled Oral Word Association Test, the Stroop Test, the Wisconsin Card Sort Test, and the Trail Making Test. Results: The two patient groups were significantly impaired on the Stroop Test at both time points compared to the control group. Significant group differences were also found for the Trail Making Test at Time 1 and for the Wisconsin Card Sort Test at Time 2. When controlled for practice effect, significant improvements over time were found on the Stroop and Trail Making tests in the schizophrenia group and on WCST Categories Achieved in the mania group. Discussion: Compared to controls, the patient groups were impaired on measures related to executive ability. The pattern of improvement on test scores between the acute and subacute phases differed between patients with schizophrenia versus patients with mania. (C) 1997 Elsevier Science B.V.

Rehabilitation of executive dysfunction: A controlled trial of an attention and problem solving treatment group

In this study, the effectiveness of a group-based attention and problem solving (APS) treatment approach to executive impairments in patients with frontal lobe lesions was investigated. Thirty participants with lesions in the frontal lobes, 16 with left frontal (LF) and 14 with right frontal (RF) lesions, were allocated into three groups, each with 10 participants. The APS treatment was initially compared to two other control conditions, an information/education (IE) approach and treatment-as-usual or traditional rehabilitation (TR), with each of the control groups subsequently receiving the APS intervention in a crossover design. This design allowed for an evaluation of the treatment through assessment before and after treatment and on follow up, six months later. There was an improvement on some executive and functional measures after the implementation of the APS programme in the three groups. Size, and to a lesser extent laterality, of lesion affected baseline performance on measures of executive function, but there was no apparent relationship between size, laterality or site of lesion and level of benefit from the treatment intervention. The results were discussed in terms of models of executive functioning and the effectiveness of domain specific interventions in the rehabilitation of executive dysfunction.

The frontal assessment battery (FAB) reveals neurocognitive dysfunction in substance-dependent individuals in distinct executive domains: Abstract reasoning, motor programming, and cognitive flexibility

Substance-dependence is highly associated with executive cognitive function (ECF) impairments. However. considering that it is difficult to assess ECF clinically, the aim of the present study was to examine the feasibility of a brief neuropsychological tool (the Frontal Assessment Battery FAB) to detect specific ECF impairments in a sample of substance-dependent individuals (SDI). Sixty-two subjects participated in this study. Thirty DSM-IV-diagnosed SDI, after 2 weeks of abstinence, and 32 healthy individuals (control group) were evaluated with FAD and other ECF-related tasks: digits forward (DF), digits backward (DB), Stroop Color Word Test (SCWT), and Wisconsin Card Sorting Test (WCST). SDI did not differ from the control group on sociodemographic variables or IQ. However, SDI performed below the controls in OF, DB, and FAB. The SDI were cognitively impaired in 3 of the 6 cognitive domains assessed by the FAB: abstract reasoning, motor programming, and cognitive flexibility. The FAB correlated with DF, SCWT, and WCST. In addition, some neuropsychological measures were correlated with the amount of alcohol, cannabis, and cocaine use. In conclusion, SDI performed more poorly than the comparison group on the FAB and the FAB`s results were associated with other ECF-related tasks. The results suggested a negative impact of alcohol, cannabis, and cocaine use on the ECF. The FAB may be useful in assisting professionals as an instrument to screen for ECF-related deficits in SDI. (C) 2010 Elsevier Ltd. All rights reserved.

Frontal Assessment Battery (FAB) is a simple tool for detecting executive deficits in chronic cannabis users

Background: Cannabis is the most used illicit drug in the world, and its use has been associated with prefrontal cortex (PFC) dysfunction, including deficits in executive functions (EF). Considering that EF may influence treatment outcome, it would be interesting to have a brief neuropsychological battery to assess EF in chronic cannabis users (CCU). In the present study, the Frontal Assessment Battery (FAB), a brief, easy to use neuropsychological instrument aimed to evaluate EF, was used to evaluate cognitive functioning of CCU. Methods: We evaluated 107 abstinent CCU with the FAB and compared with 44 controls matched for age, estimated IQ, and years of education. Results: CCU performed poorly as compared to controls (FAB total score = 16.53 vs. 17.09, p .05). CCU had also a poor performance in the Motor Programming subtest (2.47 vs. 2.73, p .05). Conclusion: This study examined effects of cannabis in executive functioning and showed evidence that the FAB is sensitive to detect EF deficits in early abstinent chronic cannabis users. Clinical significance of these findings remains to be investigated in further longitudinal studies. FAB may be useful as a screening instrument to evaluate the necessity for a complete neuropsychological assessment in this population.

Executive dysfunction in children and adolescents with temporal lobe epilepsy: Is the Wisconsin Card Sorting Test enough?

The Wisconsin Card Sorting Test (WCST) is the gold standard in the evaluation of executive dysfunction (ED) in patients with temporal lobe epilepsy (TLE). We evaluated 35 children with TLE and 25 healthy controls with the WCST and with a more comprehensive battery. Among the children with TLE, 77.14% showed impairment on the WCST. On other tests (Wechsler Intelligence Scale for Children-Digit Forward, Matching Familiar Figures Test, Trail Making Test, Word Fluency, Finger Windows, and Number-Letter Memory), impairment was demonstrated in 94.29%. The authors concluded that the WCST is a good paradigm to measure executive impairment in children with TLE: however, it may be not enough. Evaluation performed only with the WCST not only underestimated the number of patients with ED, but also missed relevant information regarding the type of ED. (C) 2009 Elsevier Inc. All rights reserved.

Executive dysfunction correlates with impaired functional status in older adults with varying degrees of cognitive impairment

Background: Previous studies have reported an association between executive dysfunction and the ability to perform activities of daily living (ADL)s among older adults. This study aims to examine the association between executive functions and functional status in a cross-section of older adults with varying degrees of cognitive impairment. Methods: 89 individuals (mean age 73.8 years) were recruited at a memory clinic in Sao Paulo, Brazil. Subjects underwent evaluation, and were allocated into three diagnostic groups according to cognitive status: normal controls (NC, n = 32), mild cognitive impairment (MCI, n = 3 1) and mild Alzheimer`s disease (AD, n=26). Executive functions were assessed with the 25-item Executive Interview (EXIT25), and functional status was measured with the Direct Assessment of Functional Status test (DAFS-R). Results: Significantly different total DAFS-R scores were observed across the three diagnostic groups. Patients with AD performed significantly worse in EXIT25 compared with subjects without dementia, and no significant differences were detected between NC and MCI patients. We found a robust negative correlation between the DAFS-R and the EXIT25 scores (r=-0.872, p < 0.001). Linear regression analyses suggested a significant influence of the EXIT-25 and the CAMCOG on the DAFS-R scores. Conclusion: Executive dysfunction and decline in general measures of cognitive functioning are associated with a lower ability to undertake instrumental ADLs. MCI patients showed worse functional status than NC subjects. MCI patients may show subtle changes in functional status that may only be captured by objective measures of ADLs.

Microscopic origin of non-Gaussian distributions of financial returns

In this paper we study the possible microscopic origin of heavy-tailed probability density distributions for the price variation of financial instruments. We extend the standard log-normal process to include another random component in the so-called stochastic volatility models. We study these models under an assumption, akin to the Born-Oppenheimer approximation, in which the volatility has already relaxed to its equilibrium distribution and acts as a background to the evolution of the price process. In this approximation, we show that all models of stochastic volatility should exhibit a scaling relation in the time lag of zero-drift modified log-returns. We verify that the Dow-Jones Industrial Average index indeed follows this scaling. We then focus on two popular stochastic volatility models, the Heston and Hull-White models. In particular, we show that in the Hull-White model the resulting probability distribution of log-returns in this approximation corresponds to the Tsallis (t-Student) distribution. The Tsallis parameters are given in terms of the microscopic stochastic volatility model. Finally, we show that the log-returns for 30 years Dow Jones index data is well fitted by a Tsallis distribution, obtaining the relevant parameters. (c) 2007 Elsevier B.V. All rights reserved.

Use of the frontal assessment battery in evaluating executive dysfunction in patients with Huntington`s disease

The frontal assessment battery (FAB) is a bedside cognitive scale designed to measure executive functions. Huntington`s disease (HD) is a neurodegenerative disorder characterized by motor, behavioral, and cognitive dysfunction. The aim of this study was to check the validity of the FAB for the evaluation of cognitive impairment in patients with HD. Forty-one patients diagnosed with HD and 53 healthy controls matched by education, sex and age were evaluated with a validated Brazilian version of the UHDRS, the VFT, the SDMT, the SIT, the MMSE, and the FAB. The diagnosis of HD was made by DNA analysis. FAB scores were lower in patients than in the controls (p < 0.001) and had significant correlations with the VFT (r = 0.79; p < 0.05), the SDMT (r = 0.80; p < 0.05), the SIT (r = 0.72; p < 0.05), the MMSE (r = 0.83; p < 0.05), the FCS (r = 0.79; p < 0.05) and the motor section of the UHDRS (r = -0.80; p < 0.05). The FAB differentiated between HD patients in the initial and later stages of the disease. The one-year longitudinal evaluation revealed a global trend toward a worsening in the second score of the FAB. The results demonstrate that the FAB presents good internal consistency and also convergent and discriminative validity; therefore it is a useful scale to assess executive functions and to evaluate cognitive impairment in patients with HD.