岩石物理力学性质对断裂附近地应力场的影响

应用离散元方法模拟研究了断裂两侧岩石的物理力学性质(包括岩石内摩擦角、弹性模量、泊松比、粘聚力等)对其附近地应力场的影响。这些因素对断裂附近的地应力场均有不同程度的影响，它们的改变均能使主应力方位和量值发生变化。而且，岩石物理力学性质的影响与断裂力学性质、边界条件等的影响是互相联系的。分别研究了单一断裂和复合断裂模型，在复合断裂模型中，断裂两侧岩石的弹性模量对应力变化的影响最大。     

Tree rings as Pb pollution archives? A comparison of 206Pb/207Pb isotope ratios in pine and other environmental media

Tree rings, if validated as an environmental archive for pollution, would provide a convenient, geographically widespread archive for studying the temporal and spatial distribution of atmospheric pollutants. We collected tree-ring records from Scots pine (Pinus sylvestris L.), ranging in age from 100 to 300 years and from one spruce (Picea abies), from sites in southern and northern Sweden and analyzed their stable lead isotopic composition (206Pb/207Pb). These results are compared to the Pb isotopic composition in soil profiles from each of the sites and temporal changes in the 206Pb/207Pb ratio in peat and lake sediment deposits in Sweden. The mineral soils at each site are characterized by high 206Pb/207Pb ratios (> 1.35), while the ratios in the mor layer are low (1.14-1.16) and characterized by atmospheric lead pollution. The 206Pb/207Pb ratios of the tree rings, typically approximately 1.18-1.20, indicate a significant (10-30%) contribution of Pb derived from the underlying mineral soil. While peat and lake sediment records show that the 206Pb/207Pb ratio of atmospheric deposition has varied over time, with a pronounced trough between approximately 1930 and 1990, the tree rings show no similar trend. Further comparison of published Pb isotope data from other tree-ring records with time series from peat bogs and herbarium samples also shows poor agreement, and indicates that tree rings always contain a mixture of pollution Pb and Pb from the underlying mineral soil. The majority of Pb in the wood is derived from atmospheric pollution either directly, through aerial interception, or indirectly, through uptake from the large pool of accumulated pollution Pb in the soil. Since the Pb isotope ratios of the wood indicate that some natural Pb is taken up into the tree, then it must also be concluded that some fraction of the pollution Pb in the wood is likewise taken up from the forest soil. Based on the Pb isotope analyses, we can only conclude that dendrochemical records are not useful in temporal studies of metal pollution.     

Rational design methodology for fire exposed load bearing structures

The state-of-art of reliability studies in the area of fire-exposed structures or structural members is illustrated, taking examples from published papers concerning load-bearing building structures of steel, reinforced concrete, and wood. In parallel, trends are described in the present development of rational structural fire design methods, principally adapted to modern loading and safety philosophy for the non-fire state. Statistically derived results are presented for fire-exposed, insulated steel structures in office buildings, giving the breakdown of the total variance in maximum steel temperature and load-bearing capacity into component variances as a function of the insulation characteristics. The safety index and probability of failure are compared numerically for different fire design procedures. The data presented are examples of the information which is required as input in a qualified systems analysis of fire exposed load-bearing structures.     

In Vitro Treatment of Melanoma Brain Metastasis by Simultaneously Targeting the MAPK and PI3K Signaling Pathways

Malignant melanoma is the most lethal form of skin cancer, with a high propensity to metastasize to the brain. More than 60% of melanomas have the BRAF^V600E mutation, which activates the mitogen-activated protein kinase (MAPK) pathway [1]. In addition, increased PI3K (phosphoinositide 3-kinase) pathway activity has been demonstrated, through the loss of activity of the tumor suppressor gene, PTEN [2]. Here, we treated two melanoma brain metastasis cell lines, H1_DL2, harboring a BRAF^V600E mutation and PTEN loss, and H3, harboring WT (wild-type) BRAF and PTEN loss, with the MAPK (BRAF) inhibitor vemurafenib and the PI3K pathway associated mTOR inhibitor temsirolimus. Combined use of the drugs inhibited tumor cell growth and proliferation in vitro in H1_DL2 cells, compared to single drug treatment. Treatment was less effective in the H3 cells. Furthermore, a strong inhibitory effect on the viability of H1_DL2 cells, when grown as 3D multicellular spheroids, was seen. The treatment inhibited the expression of pERK1/2 and reduced the expression of pAKT and p-mTOR in H1_DL2 cells, confirming that the MAPK and PI3K pathways were inhibited after drug treatment. Microarray experiments followed by principal component analysis (PCA) mapping showed distinct gene clustering after treatment, and cell cycle checkpoint regulators were affected. Global gene analysis indicated that functions related to cell survival and invasion were influenced by combined treatment. In conclusion, we demonstrate for the first time that combined therapy with vemurafenib and temsirolimus is effective on melanoma brain metastasis cells in vitro. The presented results highlight the potential of combined treatment to overcome treatment resistance that may develop after vemurafenib treatment of melanomas.     

Analysis of DFT-Based Channel Estimators for OFDM

In this paper we analyze the performance of three low-complexity channel estimators, based on the discrete Fourier transform (DFT), for orthogonal frequency-division multiplexing (OFDM) systems. Estimators of this type have been analyzed for discrete-time channels, and we extend this analysis to continuous-time channels. We present analytical expressions for their mean-squared error (MSE) and evaluate their complexity vs. symbol-error rate (SER) for 16-QAM. The analysis shows that this type of estimators may experience an irreducible error floor at high SNRs. However, in one of the three estimators the error floor can be eliminated while the complexity stays low and the performance is maximized.     

High-speed weight estimation of whole herring (Clupea harengus) using 3D machine vision

Abstract: Weight is an important parameter by which the price of whole herring (Clupea harengus) is determined. Current mechanical weight graders are capable of a high throughput but have a relatively low accuracy. For this reason, there is a need for a more accurate high‐speed weight estimation of whole herring. A 3‐dimensional (3D) machine vision system was developed for high‐speed weight estimation of whole herring. The system uses a 3D laser triangulation system above a conveyor belt moving at a speed of 1000 mm/s. Weight prediction models were developed for several feature sets, and a linear regression model using several 2‐dimensional (2D) and 3D features enabled more accurate weight estimation than using 3D volume only. Using the combined 2D and 3D features, the root mean square error of cross‐validation was 5.6 g, and the worst‐case prediction error, evaluated by cross‐validation, was ±14 g, for a sample (n = 179) of fresh whole herring. The proposed system has the potential to enable high‐speed and accurate weight estimation of whole herring in the processing plants. Practical Application: The 3D machine vision system presented in this article enables high‐speed and accurate weight estimation of whole herring, thus enabling an increase in profitability for the pelagic primary processors through a more accurate weight grading.