Geomorphic features and soil formation of arid lands in Northeastern Jordan

Arid and semiarid lands occupy about one-third of the Earth's land surface. Interpretation of soil formation and geomorphic features of arid lands is needed to assess their soil ecological potentials, limitations, problems and management needs. The objective of this paper was to study the geomorphic features and soil formation of the arid lands in northeastern Jordan, to provide information that could be used by land managers in the study area and other arid land areas. Five representative soil pedons were excavated and described in the field. Soil samples from each horizon per pedon were taken to the laboratory for chemical and physical analyses. Geomorphic features of the area were also studied. Most of studied land surfaces are plains where eolian deflation has exposed loose gravels consisting predominantly of pebbles forming desert pavements. Desert pavements cover most of the land surface, excluding the mud playas, and are composed of basalt clasts. The accumulation of calcium carbonate and gypsum within these soils create problems for their agricultural development. Accumulation of eolian fine-grained silt has resulted in the formation of a vesicular horizon. The climatic variations during the late quaternary and the late Holocene periods contributed to the development of the desert pavement and the vesicular horizons. Clay illuviation and argillic horizon development within these soils is assumed to be a relict feature from more humid climates during the Quaternary. Sustainable agricultural development of such arid lands may not be easy. In general, these soils have high erodibility, high runoff generation potential, high susceptibility to seal and crust formation, poor water-holding capacity, pedon hardening and structural instability.     

Some efficiency measures for analysis of the productive potential of Indonesian goats

Goat-keeping in Indonesia is characterized by a stagnant population, intensive production systems, production primarily by smallholders, and a strong product demand. Research is underway to identify production constraints under typical smallholder systems using a farming systems approach.Problem identification has focused on productivity problems and then breaking down the various sources of the productivity gap. Several productivity measures are reviewed and their usefulness for problem identification discussed. Smallholder survey data from selected locations in West Java are then used to identify productivity gaps existing between these farms, larger specialized farms and experiment stations.     

Phase-matched generation of coherent soft X-rays

Phase-matched harmonic conversion of visible laser light into soft x-rays was demonstrated. The recently developed technique of guided-wave frequency conversion was used to upshift light from 800 nanometers to the range from 17 to 32 nanometers. This process increased the coherent x-ray output by factors of 10(2) to 10(3) compared to the non-phase-matched case. This source uses a small-scale (sub-millijoule) high repetition-rate laser and will enable a wide variety of new experimental investigations in linear and nonlinear x-ray science.     

The economic potential of leguminous tree crops in zero-tillage cropping in Nigeria: a linear programming model

If agroforestry technologies are to be generated rapidly and effectively there has first to be established a sound basis for research methodology. This may entail no more than a repackaging of existing experimental agricultural or forestry techniques, in other cases new approaches will need to be investigated. Some of the special problems relevant to experimenting with multipurpose trees are noted. ICRAF has available a set of source materials and guidelines on Research Methodology for the Exploration and Assessment of Multipurpose Trees which are listed, and the establishment of an informal Experimental Agroforestry Network is mentioned.

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Resumen Para generar tecnologias agroforestales en forma rapida y efectiva debe primero haberse establecido bases solidas en metodologia de investigacion. Esta puede involucrar solo el re-empaque de tecnicas experimentales ya existentes en agricultura y bosques o, en otros casos, investigar nuevas formas de abordar el problema. Se señalan algunos de los problemas especiales importantes para la experimentacion con arboles de uso multiple, y se lista un conjunto de materiales y guias sobre Metodologia de Investigacion para Examinar y Evaluar Arboles de Uso Multiple, a la vez que se menciona el establecimiento de una Red Informal de Experimentaciones Agroforestales.

     

Effects of Prolonged in vitro Culture and Cryopreservation on Viability,DNA Fragmentation,Chromosome Stability and Ultrastructure of Bovine Cells from Amniotic Fluid and Umbilical Cord

The objective of this work was to study cellular types that did not participated in the gastrulation process, amniotic fluid cells (AFCs) and umbilical cord cells (UCCs), in conditions of long‐term culture and cryopreserved with different solutions. The AFCs and UCCs were used in a comparative study with ear fibroblast cells (EFCs) that were cultured in vitro until 20 cellular passages and cryopreserved in 10% dimethylsulphoxide (DMSO), 5% dimethyl formamide (DMF) and 7% glycerol (Gly) solutions. The cellular viability, ultrastructure, DNA fragmentation and chromosome stability were evaluated to determine the cellular type most resistant. In all cell types, it was possible to evaluate the AFCs until 15 passages and UCCs until 20 passages with different periods of cellular growth to reach the confluence phase. Solutions containing 10% DMSO ensured viability of 90.33 ± 5.58%, 90.56 ± 4.40% and 81.90 ± 3.31%, respectively for EFCs, AFCs and UCCs, being significantly more efficient and with less variation than other cryoprotectant solutions. The AFCs were more sensitive to cryopreservation and presented low viability rate at the passage 20 (17.2 ± 8.87%). There was no change in karyotype and nuclear fragmentation was low in all cellular passages studied. With the scanning electron analysis was possible the characterization of AFCs and UCCs in suspension. The three cellular types of cells presented different shapes and characteristics on the surface. The results demonstrate that bovine AFCs and UCCs can be isolated, cultured in vitro and cryopreserved in 10% DMSO, not causing damage to DNA and chromosomes. The UCCs were more resistant than AFCs in all aspects.     

The formation of chondrules: petrologic tests of the shock wave model

Chondrules are millimeter-sized rounded igneous rocks within chondritic meteorites. Their textures and fractionated mineral chemistries suggest that they formed by repeated, localized, brief (minutes to hours) melting of cold aggregates of mineral dust in the protoplanetary nebula. Astrophysical models of chondrule formation have been unable to explain the petrologically diverse nature of chondrites. However, a nebular shock wave model for chondrule formation agrees with many of the observed petrologic and geochemical properties of chondrules and shows how particles within the nebula are sorted by size and how rims around chondrules are formed. It also explains the volatile-rich nature of chondrule rims and the chondrite matrix.