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Mean P (mean + p)
Selected AbstractsSodiated ,-Diphosphonate Carbanions: Characterization of the Tetrameric Cubane and the Hexameric Ladder Complexes [{(iPrO)2P(O)}2CHNa]4 and [{(EtO)2P(O)}2CHNa]6EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2003Roger Nassar Abstract Reaction of the methylene diphosphonates [(RO)2P(O)]2CH2, where R = iPr or Et, with the metalating reagents NaH, nBuNa or the superbasic mixture tBuONa/nBuLi leads to monodeprotonation, and formation of the complexes [{(iPrO)2P(O)}2CHNa]4 (1) and [{(EtO)2P(O)}2CHNa]6 (2). Single-crystal X-ray diffraction studies revealed that 1 is tetrameric in the solid state, with a central Na4O4 cubane core. Each metal in 1 is rendered pentacoordinate by binding to three ,3 -O phosphoryl bridges within the cubane, a chelating phosphoryl unit, and also a single iPrO group. In contrast, the structure of 2 is hexameric, and is composed of an unusual six-rung Na6O6 ladder core. Three distinct sodium environments as well as ,1 -, ,2 - and ,3 -O phosphoryl units are present within the ladder framework. No Na,C interactions are present in either 1 or 2. All of the six-membered NaOPCPO chelate rings display localized P=O double bonds and partial multiple bonding on the P,C,P linkages (mean P,O: 1.49 Å, and mean P,C: 1.69 Å). Ab initio molecular orbital calculations (HF/6,31G*) on model complexes indicate that the hexameric arrangement found for 2 is thermodynamically more stable than the cubane structure of 1, in the absence of steric effects. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Rainfall interception in a lower montane forest in Ecuador: effects of canopy propertiesHYDROLOGICAL PROCESSES, Issue 7 2005Katrin Fleischbein Abstract Rainfall interception in forests is influenced by properties of the canopy that tend to vary over small distances. Our objectives were: (i) to determine the variables needed to model the interception loss of the canopy of a lower montane forest in south Ecuador, i.e. the storage capacity of the leaves S and of the trunks and branches St, and the fractions of direct throughfall p and stemflow pt; (ii) to assess the influence of canopy density and epiphyte coverage of trees on the interception of rainfall and subsequent evaporation losses. The study site was located on the eastern slope of the eastern cordillera in the south Ecuadorian Andes at 1900,2000 m above sea level. We monitored incident rainfall, throughfall, and stemflow between April 1998 and April 2001. In 2001, the leaf area index (LAI), inferred from light transmission, and epiphyte coverage was determined. The mean annual incident rainfall at three gauging stations ranged between 2319 and 2561 mm. The mean annual interception loss at five study transects in the forest varied between 591 and 1321 mm, i.e. between 25 and 52% of the incident rainfall. Mean S was estimated at 1·91 mm for relatively dry weeks with a regression model and at 2·46 mm for all weeks with the analytical Gash model; the respective estimates of mean St were 0·04 mm and 0·09 mm, of mean p were 0·42 and 0·63, and of mean pt were 0·003 and 0·012. The LAI ranged from 5·19 to 9·32. Epiphytes, mostly bryophytes, covered up to 80% of the trunk and branch surfaces. The fraction of direct throughfall p and the LAI correlated significantly with interception loss (Pearson's correlation coefficient r = ,0·77 and 0·35 respectively, n = 40). Bryophyte and lichen coverage tended to decrease St and vascular epiphytes tended to increase it, although there was no significant correlation between epiphyte coverage and interception loss. Our results demonstrate that canopy density influences interception loss but only explains part of the total variation in interception loss. Copyright © 2004 John Wiley & Sons, Ltd. [source] Lobular Carcinoma In Situ and Invasive Cancer: The Contralateral Breast ControversyTHE BREAST JOURNAL, Issue 5 2002Kathryn A. Carolin MD We determined if the risk of relapse is increased in patients with the concomitant diagnosis of lobular carcinoma in situ (LCIS) and an invasive cancer, suggesting the need for a more aggressive surgical approach. A retrospective chart review was conducted from the University of Michigan's Cancer Registry of patients with LCIS and a simultaneous invasive cancer and patients with invasive cancer only diagnosed between 1981 and 1997. The two groups were compared statistically with the following variables: age at diagnosis, tumor stage, histopathologic type of cancer, type of surgery, first line of treatment, relapse status with dates, site of relapse, and vital status. Statistically significant differences were found in the distribution of age (mean p = 0.0484 and median p = 0.0216), and histopathologic type of cancer (p < 0.0001). No significant difference was noted in the overall survival between the two groups (p = 0.511). There was also a significant difference in the relapse-free survival curves between the groups (p = 0.032). The risk of relapse was almost double (1.92) for the cancer-only patients relative to patients with LCIS as a histologic component of cancer. There was no significant increase in contralateral or ipsilateral breast recurrence for patients with LCIS and an invasive cancer compared to an invasive cancer alone. This lends support to the use of breast conservation therapy for invasive cancer patients with a histologic component of LCIS. The significant difference in the types of cancer may support the theory of genetic progression of LCIS to cancer, but clearly further data are required to prove this hypothesis. [source] Is screening for abdominal aortic aneurysm bad for your health and well-being?ANZ JOURNAL OF SURGERY, Issue 12 2004Carole A. Spencer Background: The purpose of the present paper was to investigate whether screening for abdominal aortic aneurysm (AAA) causes health-related quality of life to change in men or their partners. Methods: A cross-sectional case,control comparison was undertaken of men aged 65,83 years living in Perth, Western Australia, using questionnaires incorporating three validated instruments (Medical Outcomes Study Short Form,36, EuroQol EQ-5D and Hospital Anxiety and Depression Scale) as well as several independent questions about quality of life. The 2009 men who attended for ultrasound scans of the abdominal aorta completed a short prescreening questionnaire about their perception of their general health. Four hundred and ninety-eight men (157 with an AAA and 341 with a normal aorta) were sent two questionnaires for completion 12 months after screening, one for themselves and one for their partner, each being about the quality of life of the respondent. Results: Men with an AAA were more limited in performing physical activities than those with a normal aorta (t -test of means P = 0.04). After screening, men with an AAA were significantly less likely to have current pain or discomfort than those with a normal aorta (multivariate odds ratio: 0.5; 95% confidence interval (CI): 0.3,0.9) and reported fewer visits to their doctor. The mean level of self-perceived general health increased for all men from before to after screening (from 63.4 to 65.4). Conclusions: Apart from physical functioning, screening was not associated with decreases in health and well-being. A high proportion of men rated their health over the year after screening as being either the same or improved, regardless of whether or not they were found to have an AAA. [source] | ||||||||||