Involvement of chlororespiration in chilling stress in the tropical species Spathiphyllum wallisii.

Spathiphyllum wallisii plants were used to study the effect of chilling stress under high illumination on photosynthesis and chlororespiration. Leaves showed different responses that depended on root temperature. When stem, but not root, was chilled, photosystem II (PSII) was strongly photoinhibited. However, when the whole plant was chilled, the maximal quantum yield of PSII decreased only slightly below the normal values and cyclic electron transport was stimulated. Changes were also observed in the chlororespiration enzymes and PGR5. In whole plants chilled under high illumination, the amounts of NADH dehydrogenase (NDH) complex and plastid terminal oxidase (PTOX) remained similar to control and increased when only stem was chilled. In contrast, the amount of PGR5 polypeptide was higher in plants when both root and stem were chilled than in plants in which only stem was chilled. The results indicated that the contribution of chlororespiration to regulating photosynthetic electron flow is not relevant when the whole plant is chilled under high light, and that another pathway, such as cyclic electron flow involving PGR5 polypeptide, may be more important. However, when PSII activity is strongly photoinhibited in plants in which only stem is chilled, chlororespiration, together with other routes of electron input to the electron transfer chain, is probably essential.

[Utility of the clinical risk index for babies (CRIB) as a predictor of hospital death and intraventricular hemorrhage in very low birth weight and extremely low birth weight neonates]. / Utilidad del CRIB para predecir la muerte hospitalaria y la hemorragia intraventricular en los prematuros de muy bajo peso y extremado bajo peso al nacer.

OBJECTIVE: To assess the utility of the CRIB score as a predictor of hospital death and intraventricular hemorrhage (IVH) in very low birth weight (VLBW) and extremely low birth weight (ELBW) neonates. METHOD: A prospective cohort of VLBW neonates admitted to the neonatal intensive care unit from January 2002 to December 2004 was studied. The data was assessed following the protocol of the SEN 1500 multicenter study. This protocol included assessment of the CRIB score in the first 12 hours of life. Data for the entire group, as well as for two subgroups divided according to birth weight (BW) - VLBW neonates (between 1000 and 1500 g) and ELBW neonates (below 1,000 g) - were evaluated. The area under the receiver operating characteristic curve (Az) was calculated to assess the utility of CRIB score, BW and gestational age (GA). Two multivariate models were used. RESULTS: The cohort consisted of 163 patients. The mean (+/-SD) birthweight was 1.114 (+/-270) g and gestational age (+/-SD) was 29 (+/-3) weeks. The Az for hospital death was 0.757 for the CRIB, 0.758 for BW and 0.703 for GA. The Az for IVH was 0.66 for the CRIB, 0.62 for BW and 0.64 for GA. In the multivariate models for hospital death and IVH, the CRIB was the best predictor. The Az of the CRIB for hospital death was 0.77 for VLBW neonates (p < 0.001) and 0.63 for ELBW neonates (p = 0.82). CONCLUSIONS: The predictive utility of the CRIB for hospital death and IVH is similar to that of BW. In the stratification by groups of weight, we found that the CRIB was the best predictor of hospital death in the group weighing > 1,000 g but was no better than chance in the group weighing < 1,000 g.

Codimension-three bifurcations in a Bénard-Marangoni problem.

This Brief Report studies the linear stability of a thermoconvective problem in an annular domain for relatively low (~1) Prandtl (viscosity effects) and Biot (heat transfer) numbers. The four possible patterns for the instabilities, namely, hydrothermal waves of first and second class, longitudinal rolls, and corotating rolls, are present in a small region of the Biot-Prandtl plane. This region can be split in four zones, depending on the sort of instability found. The boundary of these four zones is composed of codimension-two points. Authors have also found two codimension-three points, where some of the former curves intersect. Results shown in this Brief Report clarify some reported experiments, predict new instabilities, and, by giving a deeper insight into how physical parameters affect bifurcations, open a gateway to control those instabilities.