A general model of the public goods dilemma

An individually costly act that benefits all group members is a public good. Natural selection favors individual contribution to public goods only when some benefit to the individual offsets the cost of contribution. Problems of sex ratio, parasite virulence, microbial metabolism, punishment of noncooperators, and nearly all aspects of sociality have been analyzed as public goods shaped by kin and group selection. Here, I develop two general aspects of the public goods problem that have received relatively little attention. First, variation in individual resources favors selfish individuals to vary their allocation to public goods. Those individuals better endowed contribute their excess resources to public benefit, whereas those individuals with fewer resources contribute less to the public good. Thus, purely selfish behavior causes individuals to stratify into upper classes that contribute greatly to public benefit and social cohesion and to lower classes that contribute little to the public good. Second, if group success absolutely requires production of the public good, then the pressure favoring production is relatively high. By contrast, if group success depends weakly on the public good, then the pressure favoring production is relatively weak. Stated in this way, it is obvious that the role of baseline success is important. However, discussions of public goods problems sometimes fail to emphasize this point sufficiently. The models here suggest simple tests for the roles of resource variation and baseline success. Given the widespread importance of public goods, better models and tests would greatly deepen our understanding of many processes in biology and sociality

Lessons from a fall

Frank Boyd, acting chair of IWU\u27s political science department, addressed the issue of U.S. policy in Latin American in the op-ed column Questions and Conclusions, a regular feature of IWU Magazine

Potassium current regulation and intracellular calcium stores in rat cerebellar granule neurons.

Cerebellar granule neurons (CGNs) possess a standing outward potassium current (IKso) which shares many properties with the two-pore domain potassium channel TASK-1. This thesis extends the characterisation of IKso and considers its modulation by muscarinic M3 receptor activation concentrating, in particular, on the role of intracellular calcium. IKso was found to be permeable to other monovalent cations with a permeability sequence T1+ = Rb+ = K+ >> Cs+ > NH4+ > Li+. IKso was inhibited by muscarine (10?M; 70 ± 2%, n = 61) and histamine (30?M; 25.8 ± 7.3%, n = 6 out of 9). Muscarine (10?M) was only able to evoke a rise in intracellular calcium concentration ([Ca2+]i) in a small proportion of CGN (9%). The thapsigargin sensitive, intracellular calcium stores in CGN were found to be depleted at rest and this may underlie the lack of calcium response to muscarine. In this respect, a prior depolarisation with potassium, which is shown to load calcium stores, increased the size of the calcium response and the proportion of CGN responding to muscarine (to 51%). Raising [Ca2+]i with ionomycin (1?M) elicited a small decrease in IKso (14 ± 4%, n=7). Thus, elevations in [Ca2+]i do not appear to mediate muscarinic inhibition of IKso. Muscarinic inhibition of IKso was unaffected by the inhibitors of mitogen activated protein kinase kinase (MEK), PD 98059 and U 0126. While phorbol 12- myristate 13-acetate (PMA) had no effect on IKso amplitude, it did diminish muscarinic inhibition of IKso. Surprisingly, PD 98059 and U 0126 concentration dependently diminished IKso amplitude (at 30?M by 48 ± 1% (n = 10) and 46 ± 3% (n = 7), respectively) in a voltage insensitive manner. The mechanism of block by these compounds remains unknown but is not believed to be due to an action on MEK

Induced Mutations in Molds

(From the Summary) This experiment was originally intended to investigate the mutagenic effect of certain carcinogenic drugs, and to determine the possible relationship between mutation in micro-organisms and cancer in higher tissue. Attempts to produce visible morphological mutations or modified lactose fermentation in Escherichia coli and Aerobacter aerogenes by placing the various drugs in the culture media did not yield any mutations. These same materials were then used on Aspergillus niger, by placing the chemical on absorbent discs on petri plates and examining the mold in the surrounding area for variations. This procedure also failed to yield mutations. Spores of Aspergillus niger were irradiated with ultraviolet light and plated. The resulting colonies were examined for morphological mutations. Three such variations were found and described. The processes for extraction of the pigment of one of the variants and the chemical identification of it and other components of the mycelia are described

The Recent Excitement in High-Density QCD

Over the past few months, the theory of QCD at high density has been advanced considerably. It provides new perspectives on, and controlled realizations of, confinement and chiral symmetry breaking. Here I survey the recent developments, and suggest a few directions for future work.Comment: LaTeX, 16 pages, 2 figures. Invited talk at PANIC `99, Uppsala, Sweden, June 199