Modifiability Of Strategy Use In Probabilistic Categorization By Rhesus Macaques (Macaca Mulatta) And Capuchin Monkeys (Cebus [Sapajus] Apella)

Humans and nonhuman animals categorize the natural world, and their behaviors can reveal how they use the stimulus information they encounter in service of these categorizations. Rigorous psychological study of categorization has offered many insights into the processes of categorization and their relative strengths and weaknesses across species. Probabilistic categorization, in which the relationships among stimulus information and category membership that are observed by an individual are fundamentally probabilistic, presents unique challenges both to the categorizer and to the psychologist attempting to model their behavior. Challenges notwithstanding, probabilistic categorization is an exceptionally ecologically relevant problem to human and nonhuman animal cognition alike. This dissertation reports the effects of many manipulations of theoretical interest on computer-trained rhesus macaques’ and capuchin monkeys’ inferred cognitive strategy use in a computerized version of a classic probabilistic categorization task. Experiment 1 probed cognitive strategy use across five variants of the same task in which the probability structure was constant, but the appearances and onscreen locations of cues and responses changed. Experiment 2 presented a series of manipulations of theoretical interest to the animals by changing the probability and reward structures of the task. Experiment 3 manipulated the stimuli of the task in ways motivated by findings across perceptual psychology literature. Experiment 4 extended the reward rate manipulations of Experiment 2 even further. Across four experiments, inferred strategy use was remarkably stable. Those animals that used cue-based strategies often returned to the same specific strategy experiment after experiment, as the cues, responses, probabilities, and contingencies changed around them. This finding is discussed in relation to questions of a real or functional ceiling on sophistication of strategy use, the robustness of cognitive individual differences in nonhuman primates, and future directions for comparative study of cognitive strategy use in probabilistic categorization

Randomness and Structure to Humans and Rhesus Macaques

Random, unpredictable, unstructured stimuli are an everyday part of life. Yet despite this breadth of experience and sophisticated statistical learning mechanisms, humans report patterning even in stimuli that are paradigmatically random. In two experiments, participants evaluated structured and random environments presented in a common statistical learning paradigm, the Serial Reaction Time task. I presented random and specifically nonrandom sequences to humans (Experiments 1 and 2) and rhesus macaques (Macaca mulatta, Experiment 2) to explore the seemingly antagonistic relationship between explicit, intuitive beliefs about these sequences and implicit statistical learning of sequence properties. Sequence predictability and experience with a given sequence type significantly predicted reaction times only weakly and inconsistently across the two experiments. Accordingly, participant choices scarcely deviated from chance, and in those rare cases they deviated from chance largely without directionality, and were not significantly predicted by either sequence predictability or experience with a given sequence type

A conditional trophic cascade: Birds benefit faster growing trees with strong links between predators and plants

Terrestrial systems are thought to be organized predominantly from the bottom-up, but there is a growing literature documenting top-down trophic cascades under certain ecological conditions. We conducted an experiment to examine how arthropod community structure on a foundation riparian tree mediates the ability of insectivorous birds to influence tree growth. We built whole-tree bird exclosures around 35 mature cottonwood (Populus spp.) trees at two sites in northern Utah, USA, to measure the effect of bird predation on arthropod herbivore and predator species richness, abundance, and biomass, and on tree performance. We maintained bird exclosures over two growing seasons and conducted nondestructive arthropod surveys that recorded 63652 arthropods of 689 morphospecies representing 19 orders. Five major patterns emerged: (1) We found a significant trophic cascade (18% reduction in trunk growth when birds were excluded) only at one site in one year. (2) The significant trophic cascade was associated with higher precipitation, tree growth, and arthropod abundance, richness, and biomass than other site–year combinations. (3) The trophic cascade was weak or not evident when tree growth and insect populations were low apparently due to drought. (4) Concurrent with the stronger trophic cascade, bird predation significantly reduced total arthropod abundance, richness, and biomass. Arthropod biomass was 67% greater on trees without bird predation. This pattern was driven largely by two herbivore groups (folivores and non-aphid sap-feeders) suggesting that birds targeted these groups. (5) Three species of folivores (Orthoptera: Melanoplus spp.) were strong links between birds and trees and were only present in the site and the year in which the stronger trophic cascade occurred. Our results suggest that this trophic system is predominately bottom-up driven, but under certain conditions the influence of top predators can stimulate whole tree growth. When the most limiting factor for tree growth switched from water availability to herbivory, the avian predators gained the potential to reduce herbivory. This potential could be realized when strong links between the birds and plant, i.e., species that were both abundant herbivores and preferred prey, were present

Leaf-litter leachate is distinct in optical properties and bioavailability to stream heterotrophs

Dissolved organic C (DOC) leached from leaf litter contributes to the C pool of stream ecosystems and affects C cycling in streams. We studied how differences in leaf-litter chemistry affect the optical properties and decomposition of DOC. We used 2 species of cottonwoods (Populus) and their naturally occurring hybrids that differ in leaf-litter phytochemistry and decomposition rate. We measured DOC and nutrient concentration in leaf leachates and determined the effect of DOC quality on heterotrophic respiration in 24-h incubations with stream sediments. Differences in DOC composition and quality were characterized with fluorescence spectroscopy. Rapidly decomposing leaves with lower tannin and lignin concentrations leached ~40 to 50% more DOC and total dissolved N than did slowly decomposing leaves. Rates of heterotrophic respiration were 25 to 50% higher on leachate from rapidly decomposing leaf types. Rates of heterotrophic respiration were related to metrics of aromaticity. Specifically, rates of respiration were correlated negatively with the Fluorescence Index and positively with Specific Ultraviolet Absorbance (SUVA254) and T280 tryptophan-like fluorescence peak. These results reveal that leaf-litter DOC is distinctly different from ambient streamwater DOC. The relationships between optical characteristics of leaf leachate and bioavailability are opposite those found in streamwater DOC. Differences in phytochemistry among leaf types can influence stream ecosystems with respect to DOC quantity, composition, and rates of stream respiration. These patterns suggest that the relationship between the chemical structure of DOC and its biogeochemistry is more complex than previously recognized. These unique properties of leaf-litter DOC will be important when assessing the effects of terrestrial C on aquatic ecosystems, especially during leaf fall

P3MC: A double blind parallel group randomised placebo controlled trial of Propranolol and Pizotifen in preventing migraine in children

<p>Abstract</p> <p>Background</p> <p>A recent Cochrane Review demonstrated the remarkable lack of reliable clinical trials of migraine treatments for children, especially for the two most prescribed preventative treatments in the UK, <it>Propranolol </it>and <it>Pizotifen</it>.</p> <p>Migraine trials in both children and adults have high placebo responder rates, e.g. of 23%, but for a trial's results to be generalisable "placebo responders" should not be excluded and for a drug to be worthwhile it should be clearly superior, both clinically and statistically, to placebo.</p> <p>Methods/Design</p> <p>Two multicentre, two arm double blind parallel group randomised controlled trials, with allocation ratio of 2:1 for each comparison, Propranolol versus placebo and Pizotifen versus placebo. The trial is designed to test whether Propranolol is superior to placebo and whether Pizotifen is superior to placebo for the prevention of migraine attacks in children aged 5 - 16 years referred to secondary care out-patient settings with frequent migraine (2-6/4 weeks). The primary outcome measure is the number of migraine attacks during trial weeks 11 to 14.</p> <p>Discussion</p> <p>A strength of this trial is the participation of clinically well defined migraine patients who will also be approached to help with future longer-term follow-up studies.</p> <p>Trial Registration</p> <p>ISRCTN97360154</p

A 6 Week Randomized Double-Blind Placebo-Controlled Trial of Ziprasidone for the Acute Depressive Mixed State

OBJECTIVE: To examine the efficacy of ziprasidone vs. placebo for the depressive mixed state in patients with bipolar disorder type II or major depressive disorder (MDD). METHODS: 73 patients were randomized in a double-blinded, placebo-controlled study to ziprasidone (40-160 mg/d) or placebo for 6 weeks. They met DSM-IV criteria for a major depressive episode (MDE), while also meeting 2 or 3 (but not more nor less) DSM-IV manic criteria. They did not meet DSM-IV criteria for a mixed or manic episode. Baseline psychotropic drugs were continued unchanged. The primary endpoint measured was Montgomery-Åsberg Depression Rating Scale (MADRS) scores over time. The mean dose of ziprasidone was 129.7±45.3 mg/day and 126.1±47.1 mg/day for placebo. RESULTS: The primary outcome analysis indicated efficacy of ziprasidone versus placebo (p = 0.0038). Efficacy was more pronounced in type II bipolar disorder than in MDD (p = 0.036). Overall ziprasidone was well tolerated, without notable worsening of weight or extrapyramidal symptoms. CONCLUSIONS: There was a statistically significant benefit with ziprasidone versus placebo in this first RCT of any medication for the provisional diagnostic concept of the depressive mixed state. TRIAL REGISTRATION: Clinicaltrials.gov NCT00490542

Clinical outcomes and response to treatment of patients receiving topical treatments for pyoderma gangrenosum: a prospective cohort study

Background: pyoderma gangrenosum (PG) is an uncommon dermatosis with a limited evidence base for treatment. Objective: to estimate the effectiveness of topical therapies in the treatment of PG. Methods: prospective cohort study of UK secondary care patients with a clinical diagnosis of PG suitable for topical treatment (recruited July 2009 to June 2012). Participants received topical therapy following normal clinical practice (mainly Class I-III topical corticosteroids, tacrolimus 0.03% or 0.1%). Primary outcome: speed of healing at 6 weeks. Secondary outcomes: proportion healed by 6 months; time to healing; global assessment; inflammation; pain; quality-of-life; treatment failure and recurrence. Results: Sixty-six patients (22 to 85 years) were enrolled. Clobetasol propionate 0.05% was the most commonly prescribed therapy. Overall, 28/66 (43.8%) of ulcers healed by 6 months. Median time-to-healing was 145 days (95% CI: 96 days, ∞). Initial ulcer size was a significant predictor of time-to-healing (hazard ratio 0.94 (0.88;80 1.00); p = 0.043). Four patients (15%) had a recurrence. Limitations: No randomised comparator Conclusion: Topical therapy is potentially an effective first-line treatment for PG that avoids possible side effects associated with systemic therapy. It remains unclear whether more severe disease will respond adequately to topical therapy alone

Limits to reproduction and seed size-number trade-offs that shape forest dominance and future recovery

International audienceThe relationships that control seed production in trees are fundamental to understanding the evolution of forest species and their capacity to recover from increasing losses to drought, fire, and harvest. A synthesis of fecundity data from 714 species worldwide allowed us to examine hypotheses that are central to quantifying reproduction, a foundation for assessing fitness in forest trees. Four major findings emerged. First, seed production is not constrained by a strict trade-off between seed size and numbers. Instead, seed numbers vary over ten orders of magnitude, with species that invest in large seeds producing more seeds than expected from the 1:1 trade-off. Second, gymnosperms have lower seed production than angiosperms, potentially due to their extra investments in protective woody cones. Third, nutrient-demanding species, indicated by high foliar phosphorus concentrations, have low seed production. Finally, sensitivity of individual species to soil fertility varies widely, limiting the response of community seed production to fertility gradients. In combination, these findings can inform models of forest response that need to incorporate reproductive potential

Statism and Anarchy: The Politics of Subversion in Spain, Italy, and the Soviet Union

In 1880-1914, anarchists, not social democrats or communists, defined what it meant to be a revolutionary. They articulated a dazzling imaginary in texts written in thirty languages, organized networks and trade unions on six continents, and assassinated more major leaders than any movement in history. Anarchists drew on liberal ideals and constitutional freedoms to agitate in favor of revolution, which in turn encouraged officials to deploy new techniques of surveillance and control. At the same time, anarchist activism offered pretexts and sometimes inspiration for new authoritarian movements that sought power after 1917. Far from being quixotic rebels, anarchists catalyzed a revolution—one they did not intend—during the era of the First World War. A political and intellectual history informed by political science, sociology, and social history, this dissertation argues that anarchists and regimes made, as much as fought, one another. It documents a transnational struggle between revolutionaries and rulers across Spain, Italy, and the Russian Empire/Soviet Union. The plot spans the 1870s and 1930s, focusing on 1917-23, an era of civil unrest followed by the imposition of a dictatorship in each country. The cast features those who promoted, and those who fought, the far left: militants and police chiefs, propagandists and provincial governors, rank-and-file constituents and intellectuals, assassins and cabinet ministers. Sources include politicians' writings, interior ministry records, trade-union files, newspapers, pamphlets, manifestos, and memoirs. Seven chapters investigate how left-wing activists, their political rivals, and state officials competed for influence, how anarchists articulated a resilient imaginary and built dynamic organizations, and how anarchist sensibilities inflected Soviet institutions, disappeared and then reappeared among western nonconformists, and informed new approaches in political sociology. Traditionally, historians treated anarchists as "petit-bourgeois" artisans and peasants, while political theorists made them timeless figures in "anti-statist" genealogies stretching back to Laozi. Recent scholarship rehabilitates globe-trotting activists who animated students in 1968 and contemporary protest movements (Neozapatismo, Occupy, Antifa). Such approaches all presume that anarchists were the enemies of power. By contrast, this dissertation suggests that anarchists were also the subjects and agents of power. In so doing, it uses anarchism to illuminate how politics became modern