Cooperation and Contagion in Web-Based, Networked Public Goods Experiments

A longstanding idea in the literature on human cooperation is that cooperation should be reinforced when conditional cooperators are more likely to interact. In the context of social networks, this idea implies that cooperation should fare better in highly clustered networks such as cliques than in networks with low clustering such as random networks. To test this hypothesis, we conducted a series of web-based experiments, in which 24 individuals played a local public goods game arranged on one of five network topologies that varied between disconnected cliques and a random regular graph. In contrast with previous theoretical work, we found that network topology had no significant effect on average contributions. This result implies either that individuals are not conditional cooperators, or else that cooperation does not benefit from positive reinforcement between connected neighbors. We then tested both of these possibilities in two subsequent series of experiments in which artificial seed players were introduced, making either full or zero contributions. First, we found that although players did generally behave like conditional cooperators, they were as likely to decrease their contributions in response to low contributing neighbors as they were to increase their contributions in response to high contributing neighbors. Second, we found that positive effects of cooperation were contagious only to direct neighbors in the network. In total we report on 113 human subjects experiments, highlighting the speed, flexibility, and cost-effectiveness of web-based experiments over those conducted in physical labs

Widespread resetting of DNA methylation in glioblastoma-initiating cells suppresses malignant cellular behavior in a lineage-dependent manner

Epigenetic changes are frequently observed in cancer. However, their role in establishing or sustaining the malignant state has been difficult to determine due to the lack of experimental tools that enable resetting of epigenetic abnormalities. To address this, we applied induced pluripotent stem cell (iPSC) reprogramming techniques to invoke widespread epigenetic resetting of glioblastoma (GBM)-derived neural stem (GNS) cells. GBM iPSCs (GiPSCs) were subsequently redifferentiated to the neural lineage to assess the impact of cancer-specific epigenetic abnormalities on tumorigenicity. GiPSCs and their differentiating derivatives display widespread resetting of common GBM-associated changes, such as DNA hypermethylation of promoter regions of the cell motility regulator TES (testis-derived transcript), the tumor suppressor cyclin-dependent kinase inhibitor 1C (CDKN1C; p57KIP2), and many polycomb-repressive complex 2 (PRC2) target genes (e.g., SFRP2). Surprisingly, despite such global epigenetic reconfiguration, GiPSC-derived neural progenitors remained highly malignant upon xenotransplantation. Only when GiPSCs were directed to nonneural cell types did we observe sustained expression of reactivated tumor suppressors and reduced infiltrative behavior. These data suggest that imposing an epigenome associated with an alternative developmental lineage can suppress malignant behavior. However, in the context of the neural lineage, widespread resetting of GBM-associated epigenetic abnormalities is not sufficient to override the cancer genome

Volume-Targeted Ventilation and Arterial Carbon Dioxide in Neonates

Objectives: To review the arterial carbon dioxide tensions (PaCO2) in newborn infants ventilated using synchronized intermittent mandatory ventilation (SIMV) in volume guarantee mode (using the Drager Babylog 8000+) with a unit policy targeting tidal volumes of approximately 4 mL/kg. Methods: Data on ventilator settings and arterial (PaCO2 levels were collected on all arterial blood gases (ABG; n = 288) from 50 neonates ( 65 mmHg) were determined. Results: The mean (SD) (PaCO2 during the first 48 h was 46.6 (9.0) mmHg. The mean (SD) (PaCO2 on the first blood gas of those infants commenced on volume guarantee from admission was 45.1 (12.5) mmHg. Severe hypo- or hypercapnoea occurred in 8% of infants at the time of their first blood gas measurement, and i

Seamounts

Definition: Seamounts are literally mountains rising from the seafloor. More specifically, they are “any geographically isolated topographic feature on the seafloor taller than 100 m, including ones whose summit regions may temporarily emerge above sea level, but not including features that are located on continental shelves or that are part of other major landmasses” (Staudigel et al., 2010). The term “guyot” can be used for seamounts having a truncated cone shape with a flat summit produced by erosion at sea level (Hess, 1946), development of carbonate reefs (e.g., Flood, 1999), or partial collapse due to caldera formation (e.g., Batiza et al., 1984). Seamounts <1,000 m tall are sometimes referred to as “knolls” (e.g., Hirano et al., 2008). “Petit spots” are a newly discovered subset of sea knolls confined to the bulge of subducting oceanic plates of oceanic plates seaward of deep-sea trenches (Hirano et al., 2006)

Morphogenesis of the T4 tail and tail fibers

Remarkable progress has been made during the past ten years in elucidating the structure of the bacteriophage T4 tail by a combination of three-dimensional image reconstruction from electron micrographs and X-ray crystallography of the components. Partial and complete structures of nine out of twenty tail structural proteins have been determined by X-ray crystallography and have been fitted into the 3D-reconstituted structure of the "extended" tail. The 3D structure of the "contracted" tail was also determined and interpreted in terms of component proteins. Given the pseudo-atomic tail structures both before and after contraction, it is now possible to understand the gross conformational change of the baseplate in terms of the change in the relative positions of the subunit proteins. These studies have explained how the conformational change of the baseplate and contraction of the tail are related to the tail's host cell recognition and membrane penetration function. On the other hand, the baseplate assembly process has been recently reexamined in detail in a precise system involving recombinant proteins (unlike the earlier studies with phage mutants). These experiments showed that the sequential association of the subunits of the baseplate wedge is based on the induced-fit upon association of each subunit. It was also found that, upon association of gp53 (gene product 53), the penultimate subunit of the wedge, six of the wedge intermediates spontaneously associate to form a baseplate-like structure in the absence of the central hub. Structure determination of the rest of the subunits and intermediate complexes and the assembly of the hub still require further study

Mitigating the impact of Bats in historic churches: The response of Natterer's Bats Myotis nattereri to artificial roosts and deterrence

© 2016 Zeale et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Bats frequently roost in historic churches, and these colonies are of considerable conservation value. Inside churches, bat droppings and urine can cause damage to the historic fabric of the building and to items of cultural significance. In extreme cases, large quantities of droppings can restrict the use of a church for worship and/or other community functions. In the United Kingdom, bats and their roosts are protected by law, and striking a balance between conserving the natural and cultural heritage can be a significant challenge. We investigated mitigation strategies that could be employed in churches and other historic buildings to alleviate problems caused by bats without adversely affecting their welfare or conservation status. We used a combination of artificial roost provision and deterrence at churches in Norfolk, England, where significant maternity colonies of Natterer's bats Myotis nattereri damage church features. Radio-tracking data and population modelling showed that excluding M. nattereri from churches is likely to have a negative impact on their welfare and conservation status, but that judicious use of deterrents, especially high intensity ultrasound, can mitigate problems caused by bats. We show that deterrence can be used to move bats humanely from specific roosting sites within a church and limit the spread of droppings and urine so that problems to congregations and damage to cultural heritage can be much reduced. In addition, construction of bespoke roost spaces within churches can allow bats to continue to roost within the fabric of the building without flying in the church interior. We highlight that deterrence has the potential to cause serious harm toM. nattereri populations if not used judiciously, and so the effects of deterrents will need careful monitoring, and their use needs strict regulation

Accreting Millisecond X-Ray Pulsars

Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories without parallel in the study of extreme physics. In this chapter we review the past fifteen years of discoveries in the field. We summarize the observations of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength observations that have been carried out since the discovery of the first AMXP in 1998. We review accretion torque theory, the pulse formation process, and how AMXP observations have changed our view on the interaction of plasma and magnetic fields in strong gravity. We also explain how the AMXPs have deepened our understanding of the thermonuclear burst process, in particular the phenomenon of burst oscillations. We conclude with a discussion of the open problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer; [revision with literature updated, several typos removed, 1 new AMXP added

Regulation of Granulocyte and Macrophage Populations of Murine Bone Marrow Cells by G-CSF and CD137 Protein

BACKGROUND: Granulocytes and monocytes/macrophages differentiate from common myeloid progenitor cells. Granulocyte colony-stimulating factor (G-CSF) and CD137 (4-1BB, TNFRSF9) are growth and differentiation factors that induce granulocyte and macrophage survival and differentiation, respectively. This study describes the influence of G-CSF and recombinant CD137-Fc protein on myelopoiesis. METHODOLOGY/PRINCIPAL FINDINGS: Both, G-CSF and CD137 protein support proliferation and survival of murine bone marrow cells. G-CSF enhances granulocyte numbers while CD137 protein enhances macrophage numbers. Both growth factors together give rise to more cells than each factor alone. Titration of G-CSF and CD137 protein dose-dependently changes the granulocyte/macrophage ratio in bone marrow cells. Both factors individually induce proliferation of hematopoietic progenitor cells (lin-, c-kit+) and differentiation to granulocytes and macrophages, respectively. The combination of G-CSF and CD137 protein further increases proliferation, and results in a higher number of macrophages than CD137 protein alone, and a lower number of granulocytes than G-CSF alone demonstrating that CD137 protein-induced monocytic differentiation is dominant over G-CSF-induced granulocytic differentiation. CD137 protein induces monocytic differentiation even in early hematopoietic progenitor cells, the common myeloid progenitors and the granulocyte macrophage progenitors. CONCLUSIONS/SIGNIFICANCE: This study confirms earlier data on the regulation of myelopoiesis by CD137 receptor - ligand interaction, and extends them by demonstrating the restriction of this growth promoting influence to the monocytic lineage

Factors related to transmission of and infection with Schistosoma mansoni in a village in the South-eastern Region of Brazil

In this transversal study, factors related to infection with and transmission of Schistosoma mansoni were explored. Based on stool examinations of two Kato-Katz smears of a single sample, the prevalences of schistosomiasis and geohelminths were established. In a multivariable analysis, sets of demographic, socio-economic and water contact pattern variables were tested for strength of relation with infection. Males presented a 3.39-times higher risk for infection than females. The age groups between 10-19 years and 20-30 years showed risks of infection 7.1- and 7.5-times higher, respectively, than the control age group between 0-10 years. Individuals practicing leisure activities had a 1.96-times higher risk than those without these activities. The malacological survey identified snails of the species Biomphalaria glabrata, Biomphalaria straminea and Biomphalaria tenagophila. Two exemplars of B. glabrata (0.53%) proved positive for S. mansoni. The socio-economic improvements observed in the locality suggest a protective and preventive effect towards infection with schistosomiasis, which requires further investigation with a longitudinal and more detailed study design. Considering our findings, a proposal for an integrated control program should be based on two pillars: one horizontal, which involves social empowerment and health education, and another more vertical, which delivers treatment and infrastructure improvements

Physics of Neutron Star Crusts

The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10