When Do We Learn to Cooperate? The Role of Social Learning in Social Dilemmas

In this paper, I look at the interaction between social learning and cooperative behavior. I model this using a social dilemma game with publicly observed sequential actions and asymmetric information about payoffs. I find that some informed agents in this model act, individually and without collusion, to conceal the privately optimal action. Because the privately optimal action is socially costly the behavior of informed agents can lead to a Pareto improvement in a social dilemma. In my model I show that it is possible to get cooperative behavior if information is restricted to a small but non-zero proportion of the population. Moreover, such cooperative behavior occurs in a nite setting where it is public knowledge which agent will act last. The proportion of cooperative agents within the population can be made arbitrarily close to 1 by increasing the infinite number of agents playing the game. Finally, I show that under a broad set of conditions that it is a Pareto improvement on a corner value, in the ex-ante welfare sense, for an interior proportion of the population to be informed.Asymmetric information, cooperation, efficiency, social learning, social dilemmas.

A computational study of the inclusion processes of cyclodextrins and cyclodextrin polymers

Cyclodextrins (CDs) are molecules that are composed of glucopyranose rings. Cyclodextrins can be formed from either 6, 7, or 8 glucopyranose units yielding, α-, β-, or y-Cyclodextrins respectively. Cyclodextrin polymers (COPs) can occur when glyceryl linkers are added to the previously mentioned cyclodextrins. CDs and COPs are hydrophilic, yet contain a hydrophobic cavity. This cavity allows for the binding of numerous guest molecules. Some practical purposes resulting from the host-guest interactions can be seen in cosmetology, food science, and pharmacy. Using the MacroModel Interactive Molecular Modeling System Version 5.0 we studied the binding of guest molecules to α-, β-, and y-CDs and CDPs. P-nitrophenol and p-hydroxylmethyl benzoate are bound to α-CD and α-CDP, a single pyrene is bound to β-CD and β-CDP, while two pyrenes can bind to the large cavity of y-CD and y-CDP. For all three CDPs, the number of glyceryl linker unit& was systematically varied from one to ten to look at the effect of chain length on the stability of clam-shell versus open-binding. Each structure is minimized in both a clam shell conformation, with the guest surrounded by two CDs connected by glyceryl linker units and in an open conformation, with the guest bound to only one CD of the CDP. An inverted position for open binding was also studied in α-CD and α-CDP. This position occurs when the ester group of p-hydroxylmethyl benzoate and rutro group of p-nitrophenol bind to the CD or COP as opposed to the hydroxyl groups. The results obtained show that open binding is most stable for α-, β-, and y-CDPs for all chain lengths, and that there is no optimal value or glyceryl units for dam-shell binding. The determination of whether the inverted position in open binding is preferable to the normal position is inconclusive

On the evolution and environmental dependence of the star formation rate versus stellar mass relation since z ˜ 2.

This paper discusses the evolution of the correlation between galaxy star formation rates (SFRs) and stellar mass (M*) over the last ∼10 Gyr, particularly focusing on its environmental dependence. We first present the mid-infrared (MIR) properties of the Hα-selected galaxies in a rich cluster Cl 0939+4713 at z = 0.4. We use wide-field Spitzer/MIPS 24 μm data to show that the optically red Hα emitters, which are most prevalent in group-scale environments, tend to have higher SFRs and higher dust extinction than the majority population of blue Hα sources. With an MIR stacking analysis, we find that the median SFR of Hα emitters is higher in higher density environment at z = 0.4. We also find that star-forming galaxies in high-density environment tend to have higher specific SFR (SSFR), although the trend is much less significant compared to that of SFR. This increase of SSFR in high-density environment is not visible when we consider the SFR derived from Hα alone, suggesting that the dust attenuation in galaxies depends on environment; galaxies in high-density environment tend to be dustier (by up to ∼0.5 mag), probably reflecting a higher fraction of nucleated, dusty starbursts in higher density environments at z = 0.4. We then discuss the environmental dependence of the SFR–M* relation for star-forming galaxies since z ∼ 2, by compiling our comparable, narrow-band-selected, large Hα emitter samples in both distant cluster environments and field environments. We find that the SSFR of Hα-selected galaxies (at the fixed mass of log (M*/M⊙) = 10) rapidly evolves as (1 + z)3, but the SFR–M* relation is independent of the environment since z ∼ 2, as far as we rely on the Hα-based SFRs (with M*-dependent extinction correction). Even if we consider the possible environmental variation in the dust attenuation, we conclude that the difference in the SFR–M* relation between cluster and field star-forming galaxies is always small (≲0.2 dex level) at any time in the history of the Universe since z ∼ 2

The impact of significant input of fine sediment on benthic fauna at tributary junctions: a case study of the Bermejo-Paraguay River confluence, Argentina

This study examines the morphological features, suspended sediment inputs and hydraulic conditions within a large river in association with ecological patterns before and after a tributary confluence. In order to examine these effects, the macroinvertebrate distributions from three reaches of the Paraguay and Bermejo Rivers (Paraguay-Argentina) are investigated. The Bermejo River is a tributary that supplies significant quantities of fine sediment to the Paraguay River, primarily in suspension. Two reaches were examined on the Paraguay River, upstream and downstream of the Bermejo River junction, with the third study reach located on the Bermejo River, upstream of the confluence with the Paraguay River. The results provide clear evidence that a significantly increased loading of fine sediment at a river confluence has effects on the distribution and potential movement of benthic invertebrates in the lotic environment by representing physical barriers at affected sites. These effects may be important at both local and regional scales, and such increases in suspended sediment (especially associated with anthropogenic change) may thus pose a major threat to ecosystem integrity that has been historically underestimated

Infrared Emission from the Nearby Cool Core Cluster Abell 2597

We observed the brightest central galaxy (BCG) in the nearby (z=0.0821) cool core galaxy cluster Abell 2597 with the IRAC and MIPS instruments on board the Spitzer Space Telescope. The BCG was clearly detected in all Spitzer bandpasses, including the 70 and 160 micron wavebands. We report aperture photometry of the BCG. The spectral energy distribution exhibits a clear excess in the FIR over a Rayleigh-Jeans stellar tail, indicating a star formation rate of ~4-5 solar masses per year, consistent with the estimates from the UV and its H-alpha luminosity. This large FIR luminosity is consistent with that of a starburst or a Luminous Infrared Galaxy (LIRG), but together with a very massive and old population of stars that dominate the energy output of the galaxy. If the dust is at one temperature, the ratio of 70 to 160 micron fluxes indicate that the dust emitting mid-IR in this source is somewhat hotter than the dust emitting mid-IR in two BCGs at higher-redshift (z~0.2-0.3) and higher FIR luminosities observed earlier by Spitzer, in clusters Abell 1835 and Zwicky 3146.Comment: Accepted at Ap

Normative Functional Performance Values in High School Athletes: The Functional Pre-Participation Evaluation Project

Context: The fourth edition of the Preparticipation Physical Evaluation recommends functional testing for the musculoskeletal portion of the examination; however, normative data across sex and grade level are limited. Establishing normative data can provide clinicians reference points with which to compare their patients, potentially aiding in the development of future injury-risk assessments and injury-mitigation programs. Objective: To establish normative functional performance and limb-symmetry data for high school-aged male and female athletes in the United States. Design: Cross-sectional study. Setting: Athletic training facilities and gymnasiums across the United States. Patients or Other Participants: A total of 3951 male and female athletes who participated on high school-sponsored basketball, football, lacrosse, or soccer teams enrolled in this nationwide study. Main Outcome Measure(s): Functional performance testing consisted of 3 evaluations. Ankle-joint range of motion, balance, and lower extremity muscular power and landing control were assessed via the weight-bearing ankle-dorsiflexion–lunge, single-legged anterior-reach, and anterior single-legged hop-for-distance (SLHOP) tests, respectively. We used 2-way analyses of variance and χ2 analyses to examine the effects of sex and grade level on ankle-dorsiflexion–lunge, single-legged anterior-reach, and SLHOP test performance and symmetry. Results: The SLHOP performance differed between sexes (males = 187.8% ± 33.1% of limb length, females = 157.5% ± 27.8% of limb length; t = 30.3, P \u3c .001). A Cohen d value of 0.97 indicated a large effect of sex on SLHOP performance. We observed differences for SLHOP and ankle-dorsiflexion–lunge performance among grade levels, but these differences were not clinically meaningful. Conclusions: We demonstrated differences in normative data for lower extremity functional performance during preparticipation physical evaluations across sex and grade levels. The results of this study will allow clinicians to compare sex- and grade-specific functional performances and implement approaches for preventing musculoskeletal injuries in high school-aged athletes

WTEC panel report on European nuclear instrumentation and controls

Control and instrumentation systems might be called the 'brain' and 'senses' of a nuclear power plant. As such they become the key elements in the integrated operation of these plants. Recent developments in digital equipment have allowed a dramatic change in the design of these instrument and control (I&C) systems. New designs are evolving with cathode ray tube (CRT)-based control rooms, more automation, and better logical information for the human operators. As these new advanced systems are developed, various decisions must be made about the degree of automation and the human-to-machine interface. Different stages of the development of control automation and of advanced digital systems can be found in various countries. The purpose of this technology assessment is to make a comparative evaluation of the control and instrumentation systems that are being used for commercial nuclear power plants in Europe and the United States. This study is limited to pressurized water reactors (PWR's). Part of the evaluation includes comparisons with a previous similar study assessing Japanese technology

Severe combined hyperlipidaemia and retinal lipid infiltration in a patient with Type 2 diabetes mellitus

Severe combined hyperlipidaemia has occasionally been associated with infiltration of tissues in addition to arteries and the skin. We report a woman with Type 2 diabetes mellitus (DM) and severe combined hyperlipidaemia who developed retinal lipid infiltration, resulting in blindness. A 61-year-old woman with a 15-year history of Type 2 DM was admitted following a two-week history of progressive visual loss. Examination identified lipid infiltration into the retina. Phenotypically she had severe combined hyperlipidaemia with elevated IDL cholesterol and a broad beta band on lipoprotein electrophoresis, raising the possibility of familial dysbetalipoproteinaemia. However, gene sequencing analysis indicated that the patient was homozygous for the E3/E3 allele of the ApoE gene with no mutations detected in either the coding region or intron-exon boundaries. Her lipid profile improved following dietary therapy and gemfibrozil treatment, but this had little effect on either her fundal appearances or her visual acuity. Type 2 DM plays a vital role both in allowing expression of severe combined hyperlipoproteinaemia, in addition to serving as a risk factor for complications such as tissue infiltration

A near-infrared morphological comparison of high-redshift submm and radio galaxies: massive star-forming discs vs relaxed spheroids

We present deep, high-quality K-band images of complete subsamples of powerful radio and sub-mm galaxies at z=2. The data were obtained in the best available seeing at UKIRT and Gemini North, with integration times scaled to ensure that comparable rest-frame surface brightness levels are reached for all galaxies. We fit two-dimensional axi-symmetric galaxy models to determine galaxy morphologies at rest-frame optical wavelengths > 4000A, varying luminosity, axial ratio, half-light radius, and Sersic index. We find that, while some images show evidence of galaxy interactions, >95% of the rest-frame optical light in all galaxies is well-described by these simple models. We also find a clear difference in morphology between these two classes of galaxy; fits to the individual images and image stacks reveal that the radio galaxies are moderately large (=8.4+-1.1kpc; median r{1/2}=7.8), de Vaucouleurs spheroids ( = 4.07+-0.27; median n=3.87), while the sub-mm galaxies appear to be moderately compact (=3.4+-0.3kpc; median r{1/2}=3.1kpc) exponential discs (=1.44+-0.16; median n=1.08). We show that the z=2 radio galaxies display a well-defined Kormendy relation but that, while larger than other recently-studied high-z massive galaxy populations, they are still ~1.5 times smaller than their local counterparts. The scalelengths of the starlight in the sub-mm galaxies are comparable to those reported for the molecular gas. Their sizes are also similar to those of comparably massive quiescent galaxies at z>1.5. In terms of stellar mass surface density, the majority of the radio galaxies lie within the locus defined by local ellipticals. In contrast, while best modelled as discs, most of the sub-mm galaxies have higher stellar mass densities than local galaxies, and appear destined to evolve into present-day massive ellipticals.Comment: 24 pages, 9 figure