Stability analysis of the climate-vegetation system in the northern high latitudes

The stability of the climate-vegetation system in the northern high latitudes is analysed with three climate system models of different complexity: A comprehensive 3-diniensional model of the climate system, GENESIS-IBIS, and two Earth system models of intermediate complexity (EMICs), CLIMBER-2 and MoBidiC. The biogeophysical feedback in the latitudinal belt 60-70degrees N, although positive, is not strong enough to support multiple steady states: A unique equilibrium in the climate-vegetation system is simulated by all the models on a zonal scale for present-day climate and doubled CO2 climate. EMIC simulations with decreased insolation also reveal a unique steady state. However, the climate sensitivity to tree cover, DeltaT(F), exhibits non-linear behaviour within the models. For GENESIS-IBIS and CLIMBER-2, DeltaT(F) is lower for doubled CO2 climate than for present-day climate due to a shorter snow season and increased relative significance of the hydrological effect of forest cover. For the EMICs, DeltaT(F) is higher for low tree fraction than for high tree fraction, mainly due to a time shift in spring snow melt in response to changes in tree cover. The climate sensitivity to tree cover is reduced when thermohaline circulation feedbacks are accounted for in the EMIC simulations. Simpler parameterizations of oceanic processes have opposite effects on DeltaT(F): DeltaT(F) is lower in simulations with fixed SSTs and higher in simulations with mixed layer oceans. Experiments with transient CO2 forcing show climate and vegetation not in equilibrium in the northern high latitudes at the end of the 20th century. The delayed response of vegetation and accelerated global warming lead to rather abrupt changes in northern vegetation cover in the first half of the 21st century, when vegetation cover changes at double the present day rate

Clinical outcome of adjuvant endocrine treatment according to PR and HER-2 status in early breast cancer

Patients with estrogen receptor (ER)+/progesterone receptor (PR)- and/or HER-2 overexpressing breast carcinomas may derive lower benefit from endocrine treatment. We examined retrospectively data from 972 breast cancer patients who received tamoxifen (725), tamoxifen + Gn-RH analogs (127) and aromatase inhibitors (120) as adjuvant treatments. ER+/PR- versus ER+/PR+ tumours were characterised by larger size (P = 0.001), higher tumour grade (P = 0.001), higher Ki-67 expression (P = 0.001) and lower mean ER (P = 0.000) and HER-2 expression (P = 0.000). At univariate analysis, tumour grading [hazard ratio (HR) = 4.0; 95% confidence interval (CI) = 1.4-11.1; P = 0.007], nodal status (HR = 3.4; 95% CI 1.2-5.7; P = 0.000), tumour diameter (HR = 2.9; 95% CI 1.7-4.7; P = 0.000) lack of PR expression (HR = 2.1; 95% CI 1.3-3.4; P = 0.002) and HER-2 overexpression (HR = 1.9; 95% CI 1.0-3.5; P = 0.03), as well as Ki 67 expression (HR = 1.7; 95% CI 1.0-2.7; P = 0.04) were associated with shorter disease-free survival (DFS). At the multivariate analysis, nodal status (HR = 3.6; 95% CI 1.9-6.8; P = 0.0001), lack of PR expression (HR = 2.3; 95% CI 1.3-4.0; P = 0.003) and tumour diameter (HR = 2.1; 95% CI 1.1-3.8; P = 0.018) retained their prognostic significance, whereas HER-2 overexpression was associated with a trend towards shorter DFS that was of borderline statistical significance (HR = 2.0; 95 % CI 1.0-3.9; P = 0.05). Our data suggest that lack of PR expression and HER-2 overexpression are both associated with aggressive tumour features, but the prognostic information of PR status on the risk of recurrence in endocrine-treated breast cancer patients is stronger

Modelling global terrestrial vegetation-climate interaction

By coupling an atmospheric general circulation model asynchronously with an equilibrium vegetation model, manifold equilibrium solutions of the atmosphere-biosphere system have been explored. It is found that under present-day conditions of the Earth's orbital parameters and sea-surface temperatures, two stable equilibria of vegetation patterns are possible: one corresponding to present-day sparse vegetation in the Sahel, the second solution yielding savannah which extends far into the south-western part of the Sahara. A similar picture is obtained for conditions during the last glacial maximum (21 000 years before present (BP)). For the mid-Holocene (6000 years BP), however, the model finds only one solution: the green Sahara. We suggest that this intransitive behaviour of the atmosphere-biosphere is related to a westward shift of the Hadley-Walker circulation. A conceptual model of atmosphere-vegetation dynamics is used to interpret the bifurcation as well as its change in terms of stability theory

Accelerated partial breast irradiation using 3D conformal radiotherapy: Toxicity and cosmetic outcome

Purpose: The aim of this paper is to analyze the incidence of acute and late toxicity and cosmetic outcome in breast cancer patients submitted to breast conserving surgery and three-dimensional conformal radiotherapy (3D-CRT) to deliver accelerated partial breast irradiation (APBI). Methods and materials: 84 patients were treated with 3D-CRT for APBI. This technique was assessed in patients with low risk stage I breast cancer enrolled from September 2005 to July 2011. The prescribed dose was 34/38.5 Gy delivered in 10 fractions twice daily over 5 consecutive days. Four to five nocoplanar 6 MV beams were used. In all CT scans Gross Tumor Volume (GTV) was defined around the surgical clips. A 1.5 cm margin was added by defining a Clinical Target Volume (CTV). A margin of 1 cm was added to CTV to define the planning target volume (PTV). The doseevolume constraints were followed in accordance with the NSABP/RTOG protocol. Late toxicity was evaluated according to the RTOG grading schema. The cosmetic assessment was performed using the Harvard scale. Results: Median patient age was 66 years (range 51e87). Median follow-up was 36.5 months (range 13 e83). The overall incidence of acute skin toxicities was 46.4% for grade 1 and 1% for grade 2. The incidence of late toxicity was 16.7% for grade 1, 2.4% for grade 2 and 3.6% for grade 3. No grade 4 toxicity was observed. The most pronounced grade 2 late toxicity was telangiectasia, developed in three patients. Cosmetics results were excellent for 52%, good for 42%, fair for 5% and poor for 1% of the patients. There was no statistical correlation between toxicity rates and prescribed doses (p ¼ 0.33) or irradiated volume (p ¼ 0.45). Conclusions: APBI using 3D-CRT is technically feasible with very low acute and late toxicity. Long-term results are needed to assess its efficacy in reducing the incidence of breast relapse