VALIDATING OPERATIONAL FOOD SECURITY INDICATORS AGAINST A DYNAMIC BENCHMARK

Food security indicators used in practice are static in nature, thereby foregoing the key dimension of food security. This study develops an explicitly forward-looking food insecurity indicator and relative to this dynamic benchmark, we evaluate the performance of three readily available indicators: an agricultural production, a dietary diversity, and a coping strategy index. Calculation of our "gold standard" indicator, using panel data of 274 households from Mali, shows that neglecting the future may lead to substantial underestimation of a population's food insecurity. However, when compared to our "gold standard", the alternative indicators all identify most of the food insecure, with the coping strategy index displaying the most predictive power. This is an important result, given the great demand for operational, inexpensive and reliable food insecurity indicators.Food Security and Poverty,

The Cell Density Factor CMF Regulates the Chemoattractant Receptor cAR1 in Dictyostelium

Starving Dictyostelium cells aggregate by chemotaxis to cAMP when a secreted protein called conditioned medium factor (CMF) reaches a threshold concentration. Cells expressing CMF antisense mRNA fail to aggregate and do not transduce signals from the cAMP receptor. Signal transduction and aggregation are restored by adding recombinant CMF. We show here that two other cAMP-induced events, the formation of a slow dissociating form of the cAMP receptor and the loss of ligand binding, which is the first step of ligand-induced receptor sequestration, also require CMF. Vegetative cells have very few CMF and cAMP receptors, while starved cells possess ~40,000 receptors for CMF and cAMP. Transformants overexpressing the cAMP receptor gene cAR1 show a 10-fold increase of [3H]cAMP binding and a similar increase of [125I]CMF binding; disruption of the cAR1 gene abolishes both cAMP and CMF binding. In wild-type cells, downregulation of cAR1 with high levels of cAMP also downregulates CMF binding, and CMF similarly downregulates cAMP and CMF binding. This suggests that the cAMP binding and CMF binding are closely linked. Binding of ~200 molecules of CMF to starved cells affects the affinity of the majority of the cAR1 cAMP receptors within 2 min, indicating that an amplifying mechanism allows one activated CMF receptor to regulate many cARs. In cells lacking the G-protein β subunit, cAMP induces a loss of cAMP binding, but not CMF binding, while CMF induces a reduction of CMF binding without affecting cAMP binding, suggesting that the linkage of the cell density-sensing CMF receptor and the chemoattractant cAMP receptor is through a G-protein.

Silver selective electrodes based on thioether functionalized calix[4]arenes as ionophores

Silver selective electrodes based on thioether functionalized calix[4]arenes 1 and 2 as ionophores were investigated. For both ionophores the selectivity coefficients (log kAg,M) were lower than −2.2 for Hg(II) and lower than −4.6 for other cations tested. The best results were obtained with membranes containing dithioether functionalized calix[4]arene (ionophore 2), potassium tetrakis(4-chlorophenyl) borate (KTpCIPB) and bis(1-butylpentyl)adipate (BBPA) as a plasticizer. The Ag(I)-response functions exhibited almost theoretical Nernstian slopes in the activity range 10−6–10−1M of silver ions.\ud \u

Determination of two-body potentials from n-body spectra

We show how the two-body potential may be uniquely determined from n-body spectra where the hypercentral approximation is valid. We illustrate this by considering an harmonic oscillator potential which has been altered by changing the energy or normalisation constant of the ground state of the n-body system and finding how this modifies the two-body potential. It is shown that with increasing number of particles the spectrum must be known more precisely to obtain the two-body potential to the same degree of accuracy.Comment: 13 pages of text (LATEX), 3 figures (not included, available from authors), NIKHEF-93-P

The Temporal and Spatial Scale of Microevolution: Fine-scale Color Pattern Variation in the Lake Erie Watersnake

Question: What is the temporal and spatial scale of microevolution? Hypotheses: The combined effects of natural selection and gene flow result in variation in heritable traits on fine spatial and geographic scales. Organism: The Lake Erie watersnake, Nerodia sipedon insularum. Field site: US and Canadian islands in western Lake Erie. Methods: We tested for variation in colour pattern frequency within islands, among islands, and over time using data from nearly annual censuses conducted since 1980, museum specimens, and published sources. We compared FST for a presumptive major colour pattern locus to FST for allozyme loci to determine whether spatial variation exceeded that expected by chance. We computed effective population size (Ne) based on temporal frequency changes in presumptive colour pattern alleles to determine whether temporal variation exceeded that expected by chance (Ne significantly less than ∞). Conclusions: Morph frequencies did not differ significantly within islands or between islands separated by short distances. Morph frequencies did sometimes differ significantly among distant islands and among sampling periods from 1980 to the present, but no more than expected by chance. In contrast, a marked change in morph frequency occurred between historic (prior to 1961) and recent (1980–2003) samples. Possible mechanisms include changes in the strength of selection (due to changes in predator assemblages and visual environments) and rates of gene flow (due to changes in island watersnake population size)

Limits on the neutron-antineutron oscillation time from the stability of nuclei

We refute a recent claim by Nazaruk that the limits placed on the free--space neutron--antineutron oscillation time $\tau_{{n\bar n}}$ can be improved by many orders of magnitude with respect to the estimate $\tau_{{n\bar n}}>2(T_0/\Gamma)^{1/2}$, where $T_0$ is a measured limit on the annihilation lifetime of a nucleus and $\Gamma\sim 100$ MeV is a typical antineutron-nucleus annihilation width.Comment: 4 pages, Latex, submitted to Physics Letters

Chemically modified field effect transistors: the effect of ion-pair association on the membrane potentials

A theoretical model has been developed which relates physically accessible parameters to the formation of a membrane potential. The description is an extension of a theoretical description presented previously by our group, now including divalent cations and ion-pair association. Simulations of the overall membrane potential reveal several factors that may lead to non-Nernstian response curves. For monovalent and divalent cations a reduction in the slope of the response curve (sub-Nernstian response) should virtually always be expected when ion-pair association takes place in the membrane. Ion-pair association of divalent cations and sample anions can lead to a super-Nernstian response. A diffusion potential generally reduces the Nernstian slope of the response curve. In addition, several experimental results are described which illustrate and confirm our theoretical model

Methylmercury Production in Denitrifying Woodchip Bioreactors

Several operational woodchip bioreactors were installed at the outlets of agricultural drainage systems located in east central Illinois. The potential for monomethylmercury (MMHg) production and export in these bioreactors was investigated from summer 2008 to summer 2010. The basic approach was to compare the chemistry of simultaneously-collected bioreactor inlet and outlet water samples in order to assess the extent of nitrate depletion, consumption of sulfate, and production of MMHg, plus other low-charge mercury species (LCHg). In making such a comparison, we implicitly assume that the reactor is near steady state, which is a reasonable approximation given hydraulic residence times on the order of hours. All mercury (Hg) speciation measurements were made using a first-generation mercury thiourea complex ion chromatography system for Hg speciation analysis, which reliably separates MMHg and HgII (mercuric mercury), but combines MMHg and a newly-discovered, unidentified Hg species of low charge (LCHg). Due to this analytical artifact, the results reported here constitute an upper bound on true Hg methylation. In no season was MMHg ever detected in inlet samples at concentrations at much above the detection limit of ~0.1 ng/L. However, levels of MMHg+LCHg over 2 ng/L were observed in the outlets during warm seasons when nitrate had become depleted within the bioreactor. Sulfate depletion was also observed in most samples with elevated [MMHg+LCHg]. The combination of sulfate depletion and MMHg production is consistent with nitrate inhibition of iron and sulfate reduction and with MMHg concentrations observed in other highly anaerobic environments, e.g., lake hypolimnia and wetland porewaters. The maximum [MMHg+LCHg] observed in any given bioreactor followed an inverse function of the bioreactor loading density, i.e., the ratio of the area drained to the area of the bioreactor pit. The function has a form similar to that observed for bioreactor denitrification efficacy and suggests that optimal bioreactor designs that permit substantial denitrification while minimizing Hg methylation are feasible. Finally, extremely high MMHg+LCHg levels were observed when stagnant water conditions occurred within the bioreactors. Thus, it is recommended that bioreactors not be built with bottom depresssional areas where stagnant water can reside, in order to avoid developing anoxic conditions where methylation occurs. For the same reasons, bioreactors should not be used simultaneously with controlled drainage (water table management) if restricting the drainage results in keeping the bioreactors flooded for long periods of time.Illinois Sustainable Technology Center (Grant No. HWR09215)Ope

The Proceedings of the National Māori Graduates of Psychology Symposium 2002: Making a difference

This document contains the full conference proceedings.This is the full proceedings of the National Māori Graduates of Psychology Symposium 2002. The proceeding include the following themes: Kia matāra - negotiating the challenges in Māori development, kia mau – recruitment and retention, Tuhia mai, whiua atu – research and methodology, tinia mai – interventions and treatment, taitaia i te ahi manuka – pride upon the skin

Covalent binding studies on the 14C-labeled antitumour compound 2,5-bis(1-aziridinyl)-1,4-benzoquinone. Involvement of semiquinone radical in binding to DNA, and binding to proteins and bacterial macromolecules in situ

2,5-Bis(1-aziridinyl)-1,4-benzoquinone (BABQ) is a compound from which several antitumour drugs are derived, such as Trenimone, Carboquone and Diaziquone (AZQ). The mechanism of DNA binding of BABQ was studied using 14C-labeled BABQ and is in agreement with reduction of the quinone moiety and protonation of the aziridine ring, followed by ring opening and alkylation. The one-electron reduced (semiquinone) form of BABQ alkylates DNA more efficiently than two-electron reduced or non reduced BABQ. Covalent binding to polynucleotides did not unambiguously reveal preference for binding to specific DNA bases. Attempts to elucidate further the molecular structure of DNA adducts by isolation of modified nucleosides from enzymatic digests of reacted DNA failed because of instability of the DNA adducts. The mechanism of covalent binding to protein (bovine serum albumin, BSA) appeared to be completely different from that of covalent binding to DNA. Binding of BABQ to BSA was not enhanced by reduction of the compound and was pH dependent in a way that is opposite to that of DNA alkylation. Glutathione inhibits binding of BABQ to BSA and forms adducts with BABQ in a similar pH dependence as the protein binding. The aziridine group therefore does not seem to be involved in the alkylation of BSA. Incubation of intact E. coli cells, which endogenously reduce BABQ, resulted in binding to both DNA and RNA, but also appreciable protein binding was observed