A model for the evolution of reinforcement learning in fluctuating games

Many species are able to learn to associate behaviours with rewards as this gives fitness advantages in changing environments. Social interactions between population members may, however, require more cognitive abilities than simple trial-and-error learning, in particular the capacity to make accurate hypotheses about the material payoff consequences of alternative action combinations. It is unclear in this context whether natural selection necessarily favours individuals to use information about payoffs associated with nontried actions (hypothetical payoffs), as opposed to simple reinforcement of realized payoff. Here, we develop an evolutionary model in which individuals are genetically determined to use either trial-and-error learning or learning based on hypothetical reinforcements, and ask what is the evolutionarily stable learning rule under pairwise symmetric two-action stochastic repeated games played over the individual's lifetime. We analyse through stochastic approximation theory and simulations the learning dynamics on the behavioural timescale, and derive conditions where trial-and-error learning outcompetes hypothetical reinforcement learning on the evolutionary timescale. This occurs in particular under repeated cooperative interactions with the same partner. By contrast, we find that hypothetical reinforcement learners tend to be favoured under random interactions, but stable polymorphisms can also obtain where trial-and-error learners are maintained at a low frequency. We conclude that specific game structures can select for trial-and-error learning even in the absence of costs of cognition, which illustrates that cost-free increased cognition can be counterselected under social interactions

Advances in the medical management of bowel endometriosis

Endometriosis infiltrating the bowel can be treated medically in accurately selected women not seeking conception and without overt obstructive symptomatology. When the rectosigmoid junction is involved, the probabilities of intestinal symptoms relief, undergoing surgery after treatment failure, and developing bowel obstruction during hormonal treatment are around 70%, 10%, and 1-2%, respectively. When the lesion infiltrates exclusively the mid-rectum, thus in cases of true rectovaginal endometriosis, the probabilities of intestinal symptoms relief and undergoing surgery are about 80% and 3%, respectively. Endometriotic obstructions of the rectal ampulla have not been reported. A rectosigmoidoscopy or colonoscopy should be performed systematically before starting medical therapies, also to rule out malignant tumours arising from the intestinal mucosa. Progestogens are safe, generally effective, well-tolerated, inexpensive, and should be considered as first-line medications for bowel endometriosis. Independently of symptom relief, intestinal lesions should be checked periodically to exclude nodule progression during hormonal treatment

Medical treatment of endometriosis-related pain

Available medical treatments for symptomatic endometriosis act by inhibiting ovulation, reducing serum oestradiol levels, and suppressing uterine blood flows. To this aim, several drugs can be used, with a similar magnitude of effect, in term of pain relief, independently of the mechanism of action. Conversely, safety, tolerability, and cost differ. Medications for endometriosis can be categorised into low-cost drugs, including OCs and most progestogens, and high cost drugs, including dienogest and GnRH agonists. As the individual response to different drugs is variable, a stepwise approach is suggested, starting with OCs or low-cost progestogens, and stepping up to high-cost drugs only in case of inefficacy or intolerance. Oral contraceptives may be used in women with dysmenorrhoea as their main complaint, and when only superficial peritoneal implants or ovarian endometriomas < 5 cm are present, while progestogens should be preferred in women with severe deep dyspareunia and when infiltrating lesions are identified

Surgery versus hormonal therapy for deep endometriosis : is it a choice of the physician?

Deep endometriosis, occurring approximately in 1% of women of reproductive age, represents the most severe form of endometriosis. It causes severe pain in the vast majority of affected women and it can affect the bowel and the urinary tract. Hormonal treatment of deep endometriosis with progestins, such as norethindrone acetate or dienogest, or estroprogestins is effective in relieving pain in more than 90% of women at one year follow up. Progestins and estroprogestins can be safely administered in the long-term, may be not expensive and are usually well tolerated. Therefore, they should represent the first-line treatment of deep endometriosis associated pain in women not seeking natural conception. However, hormonal treatment is ineffective or not tolerated in about 30% of women, the most common side effects being erratic bleeding, weight gain, decreased libido and headache. Surgical excision of deep endometriosis is mandatory in presence of symptomatic bowel stenosis, ureteral stenosis with secondary hydronephrosis, and when hormonal treatments fail. Surgical treatment is similarly effective as compared to hormonal treatment in relieving dismenorhea, dyspareunia and dyschezia at one year follow up in more than 90% of women with deep endometriosis. Surgical removal of the nodules may require resection of the bowel, ureter or bladder, with possible severe complications such as rectovaginal or ureterovaginal fistula and anastomotic leakage. A thorough counsel with the patient is necessary in order to pursue a therapeutic plan centered not on the endometriotic lesions, but on the patient's symptoms, priorities and expectations

Enhanced light trapping using plasmonic nanoparticles

International audiencePlasmonics is a new light trapping method used in photovoltaic (PV) solar cells. A significant enhancement of the scattered and absorbed incident light due to the use of silver nanoparticles (Ag-NPs) was observed, which yield to the exaltation of the electromagnetic field in the vicinity of these NPs. In this context, we investigate optically and morphologically the effect of the NPs size dependence on the localized surface plasmon resonance. Extinction, absorption and scattering cross sections are calculated using Mie theory

A woman&apos;s worth: The psychological impact of beliefs about motherhood, female identity, and infertility on childless women with endometriosis

In this study, we examined whether beliefs regarding motherhood, female identity, and infertility affected the psychological health of 127 childless endometriosis patients. Anxiety and depression were measured using the Hospital Anxiety and Depression Scale, while self-esteem was assessed using the Rosenberg Self-Esteem Scale. A set of six Likert-type items (1\u2009=\u2009"Not at all"; 5\u2009=\u2009"To a very great extent") was developed to explore women's beliefs. Women who were more likely to believe that childless and infertile women were less appreciated by others reported poorer psychological health. Patients' beliefs should be explored during psychological counseling. Dysfunctional beliefs about female identity, especially as regards others' perceptions, should be restructured to improve patients' psychological health

25-Hydroxyvitamin D Serum Levels and Endometriosis : Results of a Case&#8211;Control Study

The immunomodulatory, anti-inflammatory, and antiproliferative properties of vitamin D have laid the basis for a possible function of this prohormone in the pathogenesis of endometriosis. The aim of this case\u2013control study was to investigate vitamin D status, by measuring 25-hydroxyvitamin D [25(OH)D] serum levels, in women with and without endometriosis. Only Italian women of Caucasian origin aged between 18 and 45 years were deemed eligible. Enrollment was limited to the period October to May. Cases and controls were matched for month of recruitment and secondarily for age and parity. Overall, 434 women were enrolled (endometriosis n = 217; controls n = 217). The group of cases included 127 women with ovarian endometrioma and 90 patients with deep endometriosis. Mean (standard deviation) levels of 25(OH)D in women with and without endometriosis were 17.9 (7.0) ng/mL and 18.4 (7.6) ng/mL, respectively (P =.46). Analyzing the two endometriosis subgroups separately, no statistically significant differences emerged (18.7 [7.4] ng/mL in deep endometriosis group vs 17.3 [6.6] ng/mL in women with ovarian endometrioma; P =.14). Comparing the subgroup of women with deep endometriosis with paired controls, no differences occurred (18.7 [7.4] ng/mL vs 18.5 [7.7] ng/mL, P =.80). Similar data emerged when performing the same analysis for ovarian endometriomas (17.4 [6.6] ng/mL vs 18.3 [7.6] ng/mL, P =.23). The results of the present case\u2013control study do not support an association between serum vitamin D levels and different phenotypes of endometriosis

Evidence of the Generation of Isosaccharinic Acids and Their Subsequent Degradation by Local Microbial Consortia within Hyper-Alkaline Contaminated Soils, with Relevance to Intermediate Level Radioactive Waste Disposal

The contamination of surface environments with hydroxide rich wastes leads to the formation of high pH (>11.0) soil profiles. One such site is a legacy lime works at Harpur Hill, Derbyshire where soil profile indicated in-situ pH values up to pH 12. Soil and porewater profiles around the site indicated clear evidence of the presence of the α and β stereoisomers of isosaccharinic acid (ISA) resulting from the anoxic, alkaline degradation of cellulosic material. ISAs are of particular interest with regards to the disposal of cellulosic materials contained within the intermediate level waste (ILW) inventory of the United Kingdom, where they may influence radionuclide mobility via complexation events occurring within a geological disposal facility (GDF) concept. The mixing of uncontaminated soils with the alkaline leachate of the site resulted in ISA generation, where the rate of generation in-situ is likely to be dependent upon the prevailing temperature of the soil. Microbial consortia present in the uncontaminated soil were capable of surviving conditions imposed by the alkaline leachate and demonstrated the ability to utilise ISAs as a carbon source. Leachate-contaminated soil was sub-cultured in a cellulose degradation product driven microcosm operating at pH 11, the consortia present were capable of the degradation of ISAs and the generation of methane from the resultant H2/CO2 produced from fermentation processes. Following microbial community analysis, fermentation processes appear to be predominated by Clostridia from the genus Alkaliphilus sp, with methanogenesis being attributed to Methanobacterium and Methanomassiliicoccus sp. The study is the first to identify the generation of ISA within an anthropogenic environment and advocates the notion that microbial activity within an ILW-GDF is likely to influence the impact of ISAs upon radionuclide migration

New measurement of neutron capture resonances of 209Bi

The neutron capture cross section of Bi209 has been measured at the CERN n TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. Gamma-ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because Bi209 is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha-decays. In the relevant stellar range of thermal energies between kT=5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At this low temperature an important part of the heavy Pb-Bi isotopes are supposed to be synthesized by the s-process in the He shells of low mass, thermally pulsing asymptotic giant branch stars. With the improved set of cross sections we obtain an s-process fraction of 19(3)% of the solar bismuth abundance, resulting in an r-process residual of 81(3)%. The present (n,gamma) cross-section measurement is also of relevance for the design of accelerator driven systems based on a liquid metal Pb/Bi spallation target.Comment: 10 pages, 5figures, recently published in Phys. Rev.