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.     

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.     

Integrating Economic Base Theory with Regional Adjustment Models: The Nonmetropolitan Rocky Mountain West

ABSTRACT Interest in the use of adjustment models has recently increased as analysts have come to see the value of these models in the study of regional growth processes. Adjustment models are especially useful in clarifying the nature and direction of population-employment interactions. However, other models of regional growth suggest that employment should not be treated as a single homogeneous variable, as is the usual assumption in regional adjustment models. This paper looks at the issue of employment disaggregation, and suggests that adjustment models can be alternatively specified by making use of economic base theory to separate employment into at least two broad sectors. Alternative economic base specifications are tested using data for the nonmetropolitan counties (n=254) of the US. Rocky Mountain West during a recent time period. The results show that an economic base version of the adjustment model provides insights to regional change that are not available from the traditional version of the model.