A ground‐level ozone forecasting model for Santiago,Chile

A physically based model for ground‐level ozone forecasting is evaluated for Santiago, Chile. The model predicts the daily peak ozone concentration, with the daily rise of air temperature as input variable; weekends and rainy days appear as interventions. This model was used to analyse historical data, using the Linear Transfer Function/Finite Impulse Response (LTF/FIR) formalism; the Simultaneous Transfer Function (STF) method was used to analyse several monitoring stations together. Model evaluation showed a good forecasting performance across stations—for low and high ozone impacts—with power of detection (POD) values between 70 and 100%, Heidke's Skill Scores between 40% and 70% and low false alarm rates (FAR). The model consistently outperforms a pure persistence forecast. Model performance was not sensitive to different implementation options. The model performance degrades for two‐ and three‐days ahead forecast, but is still acceptable for the purpose of developing an environmental warning system at Santiago. Copyright © 2002 John Wiley & Sons, Ltd.     

Detection of geometric phases in superconducting nanocircuits

When a quantum-mechanical system undergoes an adiabatic cyclic evolution, it acquires a geometrical phase factor' in addition to the dynamical one; this effect has been demonstrated in a variety of microscopic systems. Advances in nanotechnology should enable the laws of quantum dynamics to be tested at the macroscopic level, by providing controllable artificial two-level systems (for example, in quantum dots and superconducting devices). Here we propose an experimental method to detect geometric phases in a superconducting device. The setup is a Josephson junction nanocircuit consisting of a superconducting electron box. We discuss how interferometry based on geometrical phases may be realized, and show how the effect may be applied to the design of gates for quantum computation.     

The effects of stimulation of the olfactory bulbs on the serum proteins of the rat

Resumen La estimulación electroquímica bilateral de bulbos olfatorios con corriente directa de 1 mA durante 10 segundos en ratas, produce aumento de concentration de proteinas séricas totales, albúmina y globulina .     

On the hypoglycemizing effect of metahexamide

Riassunto La Metahexamide, N(3amino-4-metilbenzenesulfonil)N-cicloesilurea, possiede nel ratto e nel coniglio un effetto ipoglicemizzante più narcato rispetto alp-tolilsulfanilbutilurea (D 860). Il nuovo farmaco si dimostra più attivo del D 860 nell'accelerare la scomparsa di glucosio da parte del diaframma isolato di ratto. La Metahexamide si distribuisce rapidamente in tutti gli organi e scompare dal sangue molto lentamente. Il maggiore effetto della Metahexamide, rispetto a composti similari, viene interpretato sulla base di un lento metabolismo e in rapporto all'intenso effetto favorente la metabolizzazione del glucosio a livello periferico.     

The approximation of long‐memory processes by an ARMA model

A mean square error criterion is proposed in this paper to provide a systematic approach to approximate a long‐memory time series by a short‐memory ARMA(1, 1) process. Analytic expressions are derived to assess the effect of such an approximation. These results are established not only for the pure fractional noise case, but also for a general autoregressive fractional moving average long‐memory time series. Performances of the ARMA(1,1) approximation as compared to using an ARFIMA model are illustrated by both computations and an application to the Nile river series. Results derived in this paper shed light on the forecasting issue of a long‐memory process. Copyright © 2001 John Wiley & Sons, Ltd.     

Neural crest origins of the neck and shoulder

The neck and shoulder region of vertebrates has undergone a complex evolutionary history. To identify its underlying mechanisms we map the destinations of embryonic neural crest and mesodermal stem cells using Cre-recombinase-mediated transgenesis. The single-cell resolution of this genetic labelling reveals cryptic cell boundaries traversing the seemingly homogeneous skeleton of the neck and shoulders. Within this assembly of bones and muscles we discern a precise code of connectivity that mesenchymal stem cells of both neural crest and mesodermal origin obey as they form muscle scaffolds. The neural crest anchors the head onto the anterior lining of the shoulder girdle, while a Hox-gene-controlled mesoderm links trunk muscles to the posterior neck and shoulder skeleton. The skeleton that we identify as neural crest-derived is specifically affected in human Klippel-Feil syndrome, Sprengel's deformity and Arnold-Chiari I/II malformation, providing insights into their likely aetiology. We identify genes involved in the cellular modularity of the neck and shoulder skeleton and propose a new method for determining skeletal homologies that is based on muscle attachments. This has allowed us to trace the whereabouts of the cleithrum, the major shoulder bone of extinct land vertebrate ancestors, which seems to survive as the scapular spine in living mammals.     

The genomic basis of adaptive evolution in threespine sticklebacks

Marine stickleback fish have colonized and adapted to thousands of streams and lakes formed since the last ice age, providing an exceptional opportunity to characterize genomic mechanisms underlying repeated ecological adaptation in nature. Here we develop a high-quality reference genome assembly for threespine sticklebacks. By sequencing the genomes of twenty additional individuals from a global set of marine and freshwater populations, we identify a genome-wide set of loci that are consistently associated with marine-freshwater divergence. Our results indicate that reuse of globally shared standing genetic variation, including chromosomal inversions, has an important role in repeated evolution of distinct marine and freshwater sticklebacks, and in the maintenance of divergent ecotypes during early stages of reproductive isolation. Both coding and regulatory changes occur in the set of loci underlying marine-freshwater evolution, but regulatory changes appear to predominate in this well known example of repeated adaptive evolution in nature.