Procedimento para linearização de isotermas de adsorção de clomazone.

O comportamento de produtos químicos em solos resulta de numerosas interações com os constituintes de suas diferentes frações, especialmente com minerais de argila e materiais húmicos. A partição dos herbicidas entre as fases líquida, sólida e gasosa determina seu movimento e grau de disponibilidade em solos e, conseqüentemente, no ambiente. A relação quantitativa entre o que é retido nas frações sólidas do solo ? adsorção ? e o que permanece em solução, em equilíbrio, é descrita por isotermas de adsorção. O conhecimento dessa relação permite que, através de técnicas de modelagem, se façam predições do destino do produto, em termos de contaminação ambiental. Neste trabalho mostra-se a obtenção de isotermas de adsorção através do ajuste linear de dados experimentais obtidos no laboratório a modelos matemáticos utilizados em estudos de adsorção, obtendo-se estimativas do coeficiente de adsorção de clomazone em Planossolo utilizado para cultivo de arroz irrigado no Estado do Rio Grande do Sul, Brasil

Postpneumonectomy syndrome: Surgical management and long-term results

ObjectivePostpneumonectomy syndrome is a rare syndrome of dynamic airway obstruction caused by extreme rotation and shift of the mediastinum after pneumonectomy, resulting in symptomatic central airway compression. We have treated this syndrome by mediastinal repositioning and placement of saline-filled prostheses into the pneumonectomy space. There is a paucity of outcome data for patients treated surgically, with only a single series of 11 patients previously reported. We analyzed our recent experience with treatment of this syndrome and report on the short and long-term outcomes and quality of life assessment of the largest series ever reported of patients treated by mediastinal repositioning.MethodsRecords were reviewed of all patients who underwent mediastinal repositioning for postpneumonectomy syndrome between January of 1992 and June of 2006. Long-term health-related quality of life was assessed by administration of the Saint George's Respiratory Questionnaire.ResultsThere were 18 patients (15 women and 3 men) with a median age of 44 years (range 14–67 years). Thirteen patients had undergone right pneumonectomy, and 5 patients had undergone left pneumonectomy. None of the patients in whom postpneumonectomy syndrome developed after left pneumonectomy had a right-sided aortic arch. Five patients had undergone pneumonectomy in childhood (age < 13 years). The median interval between pneumonectomy and mediastinal repositioning was 7.5 years (range 1.1–54.8 years). The median follow-up was 32 months (range 4–143 months). The operative mortality was 5.6% (1/18). Complications occurred in 5 patients (27.8%): pneumonia in 3 patients and acute respiratory distress syndrome in 2 patients. The median hospitalization was 6 days (range 3–155 days). Some 77% (10/13) of patients reported significant improvement in their breathing and overall state of health after surgery; 15.4% of patients (2/13) were somewhat better, and 7.7% of patients (1/13) had no improvement. No patients' condition was worse after surgery. All patients who reported improvement in their symptoms after surgery remained symptomatically improved at the time of the quality of life assessment. Some 92.3% (12/13) were not at all or only slightly limited in their social activities because of breathing problems, and 84.6% (11/13) were not at all or only slightly limited in their ability to work as a result of their physical health.ConclusionRepositioning of the mediastinum with placement of prostheses for postpneumonectomy syndrome can be performed with low mortality and morbidity. Surgical repositioning provides immediate and lasting symptomatic relief to patients in whom postpneumonectomy syndrome develops

Evidence from K2 for rapid rotation in the descendant of an intermediate-mass star

Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate, 1.13(02) hr, of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star (SDSSJ0837+1856, EPIC 211914185) is a 13,590(340) K, 0.87(03) solar-mass white dwarf. This is the highest mass measured for any pulsating white dwarf with known rotation, suggesting a possible link between high mass and fast rotation. If it is the product of single-star evolution, its progenitor was a roughly 4.0 solar-mass main-sequence B star; we know very little about the angular momentum evolution of such intermediate-mass stars. We explore the possibility that this rapidly rotating white dwarf is the byproduct of a binary merger, which we conclude is unlikely given the pulsation periods observed.Comment: 5 pages, 4 figure, 1 table; accepted for publication in The Astrophysical Journal Letter

Does the group leader matter? The impact of monitoring activities and social ties of group leaders on the repayment performance of groupbased lending Eritrea

This paper analyzes whether the effects of monitoring and social ties of the group leader and other group members on repayment performance of groups differ, using data from an extensive questionnaire held in Eritrea among participants of 102 groups. We hypothesize that the monitoring activities and social ties of the group leader have a stronger positive impact on the repayment performance of groups. The results show that social ties of the group leader do have a positive effect on repayment performance of groups, whereas this is not true for social ties of other group members. We do not find evidence for the hypothesis that monitoring activities of the group leader have a stronger positive impact on group repayment performance. All variables measuring monitoring activities, either of the group leader or the other group members, are found to be statistically insignificant.

Probing the Structure of Kepler ZZ Ceti Stars with Full Evolutionary Models-based Asteroseismology

We present an asteroseismological analysis of four ZZ Ceti stars observed with the Kepler spacecraft: GD 1212, SDSS J113655.17+040952.6, KIC 11911480, and KIC 4552982, based on a grid of full evolutionary models of DA white dwarf (WD) stars. We employ a grid of carbon-oxygen core models, characterized by a detailed and consistent chemical inner profile for the core and the envelope. In addition to the observed periods, we take into account other information from the observational data, such as amplitudes, rotational splittings, and period spacing, as well as photometry and spectroscopy. For each star, we present an asteroseismological model that closely reproduces their observed properties. The asteroseismological stellar mass and effective temperature of the target stars are (0.632 ± 0.027 M, 10737 ± 73 K) for GD 1212, (0.745 ± 0.007 M, 11110 ± 69 K) for KIC 4552982, (05480 ± 0.01 M, 12,721 ± 228 K) for KIC11911480, and (0.570 ± 0.01 M, 12,060 ± 300 K) for SDSS J113655.17+040952.6. In general, the asteroseismological values are in good agreement with the spectroscopy. For KIC 11911480 and SDSS J113655.17+040952.6 we derive a similar seismological mass, but the hydrogen envelope is an order of magnitude thinner for SDSS J113655.17+040952.6, which is part of a binary system and went through a common envelope phase