Letter from New York

Julia Crowe interviews Peter Argondizza in New York regarding his career as a guitarist

Should organic farmers be rewarded for sequestering C in soil?

The question of whether farmers, and organic farmers in particular, should be rewarded for sequestering C in soils is controversial. A review of the literature on long term experiments comparing organic and conventional systems, demonstrates that soils under organic management tend to have higher soil organic carbon (SOC) contents than conventionally managed soils. But the logistics of designing a system that compensates individual farmers for this ecosystem service are challenging. Agreements would have to be reached on the baseline system used for calculation of relative gains in SOC, values for emissions of other GHGs from soils (e.g. methane and nitrous oxide), the direct and indirect CO2 emissions associated with energy use and crop production inputs in the C sequestering system, and emissions associated with sources of SOC imported onto the farm. Alternatively, the evidence for generally higher SOC under organic management could justify an additional payment, for example under the UK Government’s Organic Entry Level Scheme

Sensitivity of inferences in forensic genetics to assumptions about founding genes

Many forensic genetics problems can be handled using structured systems of discrete variables, for which Bayesian networks offer an appealing practical modeling framework, and allow inferences to be computed by probability propagation methods. However, when standard assumptions are violated--for example, when allele frequencies are unknown, there is identity by descent or the population is heterogeneous--dependence is generated among founding genes, that makes exact calculation of conditional probabilities by propagation methods less straightforward. Here we illustrate different methodologies for assessing sensitivity to assumptions about founders in forensic genetics problems. These include constrained steepest descent, linear fractional programming and representing dependence by structure. We illustrate these methods on several forensic genetics examples involving criminal identification, simple and complex disputed paternity and DNA mixtures.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS235 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Does Private and Cost-Priced Higher Education Produce Poor Quality?

Since the beginning of the transition, Hungarian higher education has been undergoing continuous transformation. The number of students in higher education more than doubled, and this was accompanied by the appearance of newly founded church-run and private higher education institutions and newly established cost-priced places. The paper focuses on the potential negative effects private and cost-priced higher education might have on the quality of the education and students by making use of labour market success indicators (wages and labour market status) with the help of multivariate estimation techniques. A unique data set, the Second Fid‚v Survey, is used which provides information about the September 2000 labour market situation of persons graduated from higher education in 1999. The results suggest that education at cost-priced, state funded places and private higher education institutions provides essentially the same level of knowledge or produces the same educational quality as measured by wages. No negative effect has been detected as for the labour market status of exstudents. Students from cost-priced places and private institutions experience the same unemployment probability, whereas the overall employment probability of students graduated from cost-priced places is higher than that of persons studied at state-funded places. One can conclude that although the opportunity of establishing more and more cost-priced places might have been advantageous for higher education institutions so as to increase their revenues, they have shown some selfrestraint in this respect, and there is no sign that the increase in costpriced places has led to lower quality workers.

Neutrinos from active black holes, sources of ultra high energy cosmic rays

A correlation between the highest energy Cosmic Rays (above ~ EeV) and the distribution of active galactic nuclei (AGN) gives rise to a prediction of neutrino production in the same sources. In this paper, we present a detailed AGN model, predicting neutrino production near the foot of the jet, where the photon fields from the disk and synchrotron radiation from the jet itself create high optical depths for proton-photon interactions. The protons escape from later shocks where the emission region is optically thin for proton-photon interactions. Consequently, Cosmic Rays are predicted to come from FR-I galaxies, independent of the orientation of the source. Neutrinos, on the other hand, are only observable from sources directing their jet towards Earth, i.e. flat spectrum radio sources and in particular BL Lac type objects, due to the strongly boosted neutrino emission.Comment: Accepted for publication in Astroparticle Physics; 30 pages, 8 figure

An extension of Tur\'an's Theorem, uniqueness and stability

We determine the maximum number of edges of an $n$-vertex graph $G$ with the property that none of its $r$-cliques intersects a fixed set $M\subset V(G)$. For $(r-1)|M|\ge n$, the $(r-1)$-partite Turan graph turns out to be the unique extremal graph. For $(r-1)|M|<n$, there is a whole family of extremal graphs, which we describe explicitly. In addition we provide corresponding stability results.Comment: 12 pages, 1 figure; outline of the proof added and other referee's comments incorporate