The SADC Groundwater Data and Information Archive, Knowledge Sharing and Co-operation Project. Final report

The Southern African Development Community (SADC) Groundwater Data and Information Archive, Knowledge Sharing and Co-operation Project, funded by the German Development Cooperation (GIZ) and Department for International Development, UK (DFID), was initiated in September 2009 to identify, catalogue and subsequently promote access to the large collection of reports held in the UK by the British Geological Survey (BGS). The work has focused on a wealth of unpublished so-called “grey” data and information which describes groundwater occurrence and development in Southern Africa and was gathered by the BGS over its many decades of involvement in the region. The project has four main aims: To catalogue and describe the "grey data" documents on SADC groundwater held by the BGS within a digital metadatabase. To identify a sub-set of scanned documents to be made freely available to groundwater practitioners and managers in the SADC region by electronic distribution. To link the metadatabase and digital sub-set of documents via a web portal hosted by the BGS, to enable download of documents by SADC groundwater workers. To strengthen links between BGS hydrogeologists with counterparts in SADC, and provide an example of groundwater data sharing which could be emulated by other European Geological Surveys with substantial data holdings on SADC groundwater. The project has successfully met these aims. The assessment of BGS archived material produced an electronic meta-database describing 1735 items held in hard copy. Of these, 1041 have been scanned digitally to searchable Portable Document Format (PDF) format. A subset of 655 PDFs including partial documents related to groundwater development from the colonial and post independence period as well as BGS internal project reports and reports approved for web dissemination by host countries are now available to download (free of charge) at http://www.SADCgroundwaterarchive.com . Initial results indicate a good deal of interest both from within SADC and elsewhere, accessed by directly addressing the website and via a search engine such as Google. The information presented has already been used by in-region projects such as the SADC Hydrogeological Mapping project and the Malawi Water Assessment Project. This is essentially a pilot project providing an example of how Web delivery of the archive is an important step forward for the well-being of the SADC region. It permits access to documents few even new existed and will, it is hoped, provide a valuable dataset that should inhibit the temptation to waste scarce resources by ‘re-inventing the wheel’

Mechanism and function of drosophila capa GPCR: a desiccation stress-responsive receptor with functional homology to human neuromedinU receptor

The capa peptide receptor, capaR (CG14575), is a G-protein coupled receptor (GPCR) for the D. melanogaster capa neuropeptides, Drm-capa-1 and -2 (capa-1 and -2). To date, the capa peptide family constitutes the only known nitridergic peptides in insects, so the mechanisms and physiological function of ligand-receptor signalling of this peptide family are of interest. Capa peptide induces calcium signaling via capaR with EC50 values for capa-1 = 3.06 nM and capa-2 = 4.32 nM. capaR undergoes rapid desensitization, with internalization via a b-arrestin-2 mediated mechanism but is rapidly re-sensitized in the absence of capa-1. Drosophila capa peptides have a C-terminal -FPRXamide motif and insect-PRXamide peptides are evolutionarily related to vertebrate peptide neuromedinU (NMU). Potential agonist effects of human NMU-25 and the insect -PRLamides [Drosophila pyrokinins Drm-PK-1 (capa-3), Drm-PK-2 and hugin-gamma [hugg]] against capaR were investigated. NMU-25, but not hugg nor Drm-PK-2, increases intracellular calcium ([Ca2+]i) levels via capaR. In vivo, NMU-25 increases [Ca2+]i and fluid transport by the Drosophila Malpighian (renal) tubule. Ectopic expression of human NMU receptor 2 in tubules of transgenic flies results in increased [Ca2+]i and fluid transport. Finally, anti-porcine NMU-8 staining of larval CNS shows that the most highly immunoreactive cells are capa-producing neurons. These structural and functional data suggest that vertebrate NMU is a putative functional homolog of Drm-capa-1 and -2. capaR is almost exclusively expressed in tubule principal cells; cell-specific targeted capaR RNAi significantly reduces capa-1 stimulated [Ca2+]i and fluid transport. Adult capaR RNAi transgenic flies also display resistance to desiccation. Thus, capaR acts in the key fluid-transporting tissue to regulate responses to desiccation stress in the fly

Drell-Yan production at small q_T, transverse parton distributions and the collinear anomaly

Using methods from effective field theory, an exact all-order expression for the Drell-Yan cross section at small transverse momentum is derived directly in q_T space, in which all large logarithms are resummed. The anomalous dimensions and matching coefficients necessary for resummation at NNLL order are given explicitly. The precise relation between our result and the Collins-Soper-Sterman formula is discussed, and as a by-product the previously unknown three-loop coefficient A^(3) is obtained. The naive factorization of the cross section at small transverse momentum is broken by a collinear anomaly, which prevents a process-independent definition of x_T-dependent parton distribution functions. A factorization theorem is derived for the product of two such functions, in which the dependence on the hard momentum transfer is separated out. The remainder factors into a product of two functions of longitudinal momentum variables and x_T^2, whose renormalization-group evolution is derived and solved in closed form. The matching of these functions at small x_T onto standard parton distributions is calculated at O(alpha_s), while their anomalous dimensions are known to three loops.Comment: 32 pages, 2 figures; version to appear in Eur. Phys. J.

Double transverse spin asymmetries in vector boson production

We investigate a helicity non-flip double transverse spin asymmetry in vector boson production in hadron-hadron scattering, which was first considered by Ralston and Soper at the tree level. It does not involve transversity functions and in principle also arises in W-boson production for which we present the expressions. The asymmetry requires observing the transverse momentum of the vector boson, but it is not suppressed by explicit inverse powers of a large energy scale. However, as we will show, inclusion of Sudakov factors causes suppression of the asymmetry, which increases with energy. Moreover, the asymmetry is shown to be approximately proportional to x_1 g_1(x_1) x_2 \bar g_1(x_2), which gives rise to additional suppression at small values of the light cone momentum fractions. This implies that it is negligible for Z or W production and is mainly of interest for \gamma^* at low energies. We also compare the asymmetry with other types of double transverse spin asymmetries and discuss how to disentangle them.Comment: 12 pages, Revtex, 2 Postscript figures, uses aps.sty, epsf.sty; figures replaced, a few minor other correction

Structure Functions are not Parton Probabilities

The common view that structure functions measured in deep inelastic lepton scattering are determined by the probability of finding quarks and gluons in the target is not correct in gauge theory. We show that gluon exchange between the fast, outgoing partons and target spectators, which is usually assumed to be an irrelevant gauge artifact, affects the leading twist structure functions in a profound way. This observation removes the apparent contradiction between the projectile (eikonal) and target (parton model) views of diffractive and small x_{Bjorken} phenomena. The diffractive scattering of the fast outgoing quarks on spectators in the target causes shadowing in the DIS cross section. Thus the depletion of the nuclear structure functions is not intrinsic to the wave function of the nucleus, but is a coherent effect arising from the destructive interference of diffractive channels induced by final state interactions. This is consistent with the Glauber-Gribov interpretation of shadowing as a rescattering effect.Comment: 35 pages, 8 figures. Discussion of physical consequences of final state interactions amplified. Material on light-cone gauge choices adde

Recoil and Threshold Corrections in Short-distance Cross Sections

We identify and resum corrections associated with the kinematic recoil of the hard scattering against soft-gluon emission in single-particle inclusive cross sections. The method avoids double counting and conserves the flow of partonic energy. It reproduces threshold resummation for high-p_T single-particle cross sections, when recoil is neglected, and Q_T-resummation at low Q_T, when higher-order threshold logarithms are suppressed. We exhibit explicit resummed cross sections, accurate to next-to-leading logarithm, for electroweak annihilation and prompt photon inclusive cross sections.Comment: minor modifications of the text, some references added. 51 pages, LaTeX, 6 figures as eps file

Surface and capillary transitions in an associating binary mixture model

We investigate the phase diagram of a two-component associating fluid mixture in the presence of selectively adsorbing substrates. The mixture is characterized by a bulk phase diagram which displays peculiar features such as closed loops of immiscibility. The presence of the substrates may interfere the physical mechanism involved in the appearance of these phase diagrams, leading to an enhanced tendency to phase separate below the lower critical solution point. Three different cases are considered: a planar solid surface in contact with a bulk fluid, while the other two represent two models of porous systems, namely a slit and an array on infinitely long parallel cylinders. We confirm that surface transitions, as well as capillary transitions for a large area/volume ratio, are stabilized in the one-phase region. Applicability of our results to experiments reported in the literature is discussed.Comment: 12 two-column pages, 12 figures, accepted for publication in Physical Review E; corrected versio

Electronic states and transport properties in the Kronig-Penney model with correlated compositional and structural disorder

We study the structure of the electronic states and the transport properties of a Kronig-Penney model with weak compositional and structural disorder. Using a perturbative approach we obtain an analytical expression for the localisation length which is valid for disorder with arbitrary correlations. We show how to generate disorder with self- and cross-correlations and we analyse both the known delocalisation effects of the long-range self-correlations and new effects produced by cross-correlations. We finally discuss how both kinds of correlations alter the transport properties in Kronig-Penney models of finite size.Comment: 23 pages, 5 figure

How the composition of sandstone matrices affects rates of soil formation

Soils deliver multiple ecosystem services and their long-term sustainability is fundamentally controlled by the rates at which they form and erode. Our knowledge and understanding of soil formation is not commensurate with that of soil erosion, in part due to the difficulty of measuring the former. However, developments in cosmogenic radionuclide accumulation models have enabled soil scientists to more accurately constrain the rates at which soils form from bedrock. To date, all three major rock types – igneous, sedimentary and metamorphic lithologies – have been examined in such work. Soil formation rates have been measured and compared between these rock types, but the impact of rock characteristics on soil formation rates, such as rock matrices and mineralogy, have seldom been explored. In this UK-based study, we used cosmogenic radionuclide analysis to investigate whether the lithological variability of sandstone governs pedogenesis. Soil formation rates were measured on two arable hillslopes at Woburn and Hilton, which are underlain by different types of arenite sandstone. Rates were faster at Woburn, and we suggest that this is due to the fact that the Woburn sandstone formation is less cemented that that at Hilton. Similarly, rates at Woburn and Hilton were found to be faster than those measured at two other sandstone-based sites in the UK, and faster than those compiled in a global inventory of cosmogenic studies on sandstone-based soils. We suggest that the cementing agents present in matrix-abundant wackes studied previously may afford these sandstones greater structural integrity and resistance to weathering. This work points to the importance of factoring bedrock matrices into our understanding of soil formation rates, and the biogeochemical cycles these underpi