Seasonal variations in carbon, nitrogen and phosphorus concentrations and C:N:P stoichiometry in different organs of a Larix principis-rupprechtii Mayr. plantation in the Qinling Mountains, China

Understanding how concentrations of elements and their stoichiometry change with plant growth and age is critical for predicting plant community responses to environmental change. Weusedlong-term field experiments to explore how the leaf, stem and root carbon (C), nitrogen (N) and phosphorous (P) concentrations and their stoichiometry changed with growth and stand age in a L.principis-rupprechtii Mayr. plantation from 2012–2015 in the Qinling Mountains, China. Our results showed that the C, N and P concentrations and stoichiometric ratios in different tissues of larch stands were affected by stand age, organ type andsampling month and displayed multiple correlations with increased stand age in different growing seasons. Generally, leaf C and N concentrations were greatest in the fast-growing season, but leaf P concentrations were greatest in the early growing season. However, no clear seasonal tendencies in the stem and root C, N and P concentrations were observed with growth. In contrast to N and P, few differences were found in organ-specific C concentrations. Leaf N:P was greatest in the fast-growing season, while C:N and C:P were greatest in the late-growing season. No clear variations were observed in stem and root C:N, C:P andN:Pthroughout the entire growing season, but leaf N:P was less than 14, suggesting that the growth of larch stands was limited by N in our study region. Compared to global plant element concentrations and stoichiometry, the leaves of larch stands had higher C, P, C:NandC:PbutlowerNandN:P,andtherootshadgreater PandC:NbutlowerN,C:Pand N:P. Our study provides baseline information for describing the changes in nutritional elements with plant growth, which will facilitates plantation forest management and restoration, and makes avaluable contribution to the global data pool on leaf nutrition and stoichiometry

Activated mammalian target of rapamycin is a potential therapeutic target in gastric cancer

<p>Abstract</p> <p>Background</p> <p>The mammalian target of rapamycin (mTOR) plays a key role in cellular growth and homeostasis. The purpose of our present study is to investigate the expression of activated mTOR (p-mTOR) in gastric cancer patients, their prognostic significance and the inhibition effect of RAD001 on tumor growth and to determine whether targeted inhibition of mTOR could be a potential therapeutic strategy for gastric cancer.</p> <p>Methods</p> <p>The expression of p-mTOR was detected in specimens of 181 gastric cancers who underwent radical resection (R0) by immunohistochemistry. The correlation of p-mTOR expression to clinicopathologic features and survival of gastric cancer was studied. We also determined the inhibition effect of RAD001 on tumor growth using BGC823 and AGS human gastric cancer cell lines.</p> <p>Results</p> <p>Immunostaining for p-mTOR was positive in 93 of 181 (51.4%) gastric cancers, closely correlated with lymph node status and pTNM stage. Patients with p-mTOR positive showed significantly shorter disease-free survival (DFS) and overall survival (OS) rates than those with p-mTOR-negative tumors in univariable analyses, and there was a trend toward a correlation between p-mTOR expression and survival in multivariable analyses. RAD001 markedly inhibited dose-dependently proliferation of human gastric carcinoma cells by down-regulating expression of p70s6k, p-p70s6k, C-myc, CyclinD1 and Bcl-2, up-regulating expression of P53.</p> <p>Conclusions</p> <p>In gastric cancer, p-mTOR is a potential therapeutic target and RAD001 was a promising treatment agent with inducing cell cycle arrest and apoptosis by down-regulating expression of C-myc, CyclinD1 and Bcl-2, up-regulating expression of P53.</p

Piston-driven numerical wave tank based on WENO solver of well-balanced shallow water equations

A numerical wave tank equipped with a piston type wave-maker is presented for long-duration simulations of long waves in shallow water. Both wave maker and tank are modelled using the nonlinear shallow water equations, with motions of the numerical piston paddle accomplished via a linear mapping technique. Three approaches are used to increase computational efficiency and accuracy. First, the model satisfies the exact conservation property (C-property), a stepping stone towards properly balancing each term in the governing equation. Second, a high-order weighted essentially non-oscillatory (WENO) method is used to reduce accumulation of truncation error. Third, a cut-off algorithm is implemented to handle contaminated digits arising from round-off error. If not treated, such errors could prevent a numerical scheme from satisfying the exact C-property in long-duration simulations. Extensive numerical tests are performed to examine the well-balanced property, high order accuracy, and shock-capturing ability of the present scheme. Correct implementation of the wave paddle generator is verified by comparing numerical predictions against analytical solutions of sinusoidal, solitary, and cnoidal waves. In all cases, the model gives satisfactory results for small-amplitude, low frequency waves. Error analysis is used to investigate model limitations and derive a user criterion for long wave generation by the model

Space-time variation of malaria incidence in Yunnan province, China

Abstract Background Understanding spatio-temporal variation in malaria incidence provides a basis for effective disease control planning and monitoring. Methods Monthly surveillance data between 1991 and 2006 for Plasmodium vivax and Plasmodium falciparum malaria across 128 counties were assembled for Yunnan, a province of China with one of the highest burdens of malaria. County-level Bayesian Poisson regression models of incidence were constructed, with effects for rainfall, maximum temperature and temporal trend. The model also allowed for spatial variation in county-level incidence and temporal trend, and dependence between incidence in June–September and the preceding January–February. Results Models revealed strong associations between malaria incidence and both rainfall and maximum temperature. There was a significant association between incidence in June–September and the preceding January–February. Raw standardised morbidity ratios showed a high incidence in some counties bordering Myanmar, Laos and Vietnam, and counties in the Red River valley. Clusters of counties in south-western and northern Yunnan were identified that had high incidence not explained by climate. The overall trend in incidence decreased, but there was significant variation between counties. Conclusion Dependence between incidence in summer and the preceding January–February suggests a role of intrinsic host-pathogen dynamics. Incidence during the summer peak might be predictable based on incidence in January–February, facilitating malaria control planning, scaled months in advance to the magnitude of the summer malaria burden. Heterogeneities in county-level temporal trends suggest that reductions in the burden of malaria have been unevenly distributed throughout the province

Experimental investigation on hydrodynamic performance of a breakwater-integrated WEC system

An integrated breakwater-WEC system, which comprises of an array of heaving Oscillating Buoy Wave Energy Converters (OB-WECs) attached at the weather side of a fixed breakwater, is proposed in this study. Detailed experiments have been undertaken to investigate the heaveresponse-amplitude operator (HRAO), the wave force on the WEC devices and the transmission coefficient of the breakwater-WEC system. The design of the experiment is validated by comparing the HRAO of the devices with the corresponding numerical results. The hydrodynamic performance of the breakwater-WEC system is compared with that of its isolated counterparts, i.e., the isolated WEC array and the isolated breakwater. Parametric studies are conducted to optimise the draft of the WEC devices and the breakwater-WEC spacing, i.e. the gap between the WEC devices and the breakwater. Results show that, compared with the case of isolated WEC devices, the wave force and HRAO of the WEC devices are amplified for a properly designed breakwater-WEC system. Even though the external damping (caused by viscous damping and the friction loss) plays an important role while evaluating the efficiency of the WECs, the existence of the breakwater significantly improves the performance of the WEC array. The HRAO is sensitive to the draft of the devices and breakwater-WEC spacing.National Natural Science Foundation of China; Royal Academy of Engineerin

Experimental investigation on hydrodynamic performance of a breakwater- integrated WEC system

An integrated breakwater-WEC system, which comprises of an array of heaving Oscillating Buoy Wave Energy Converters (OB-WECs) attached at the weather side of a fixed breakwater, is proposed in this study. Detailed experiments have been undertaken to investigate the heaveresponse-amplitude operator (HRAO), the wave force on the WEC devices and the transmission coefficient of the breakwater-WEC system. The design of the experiment is validated by comparing the HRAO of the devices with the corresponding numerical results. The hydrodynamic performance of the breakwater-WEC system is compared with that of its isolated counterparts, i.e., the isolated WEC array and the isolated breakwater. Parametric studies are conducted to optimise the draft of the WEC devices and the breakwater-WEC spacing, i.e. the gap between the WEC devices and the breakwater. Results show that, compared with the case of isolated WEC devices, the wave force and HRAO of the WEC devices are amplified for a properly designed breakwater-WEC system. Even though the external damping (caused by viscous damping and the friction loss) plays an important role while evaluating the efficiency of the WECs, the existence of the breakwater significantly improves the performance of the WEC array. The HRAO is sensitive to the draft of the devices and breakwater-WEC spacing

Boussinesq cut-cell model for non-linear wave interaction with coastal structures

Boussinesq models describe the phase-resolved hydrodynamics of unbroken waves and wave-induced currents in shallow coastal waters. Many enhanced versions of the Boussinesq equations are available in the literature, aiming to improve the representation of linear dispersion and non-linearity. This paper describes the numerical solution of the extended Boussinesq equations derived by Madsen and Sørensen (Coastal Eng. 1992; 15:371-388) on Cartesian cut-cell grids, the aim being to model non-linear wave interaction with coastal structures. An explicit second-order MUSCL-Hancock Godunov-type finite volume scheme is used to solve the non-linear and weakly dispersive Boussinesq-type equations. Interface fluxes are evaluated using an HLLC approximate Riemann solver. A ghost-cell immersed boundary method is used to update flow information in the smallest cut cells and overcome the time step restriction that would otherwise apply. The model is validated for solitary wave reflection from a vertical wall, diffraction of a solitary wave by a truncated barrier, and solitary wave scattering and diffraction from a vertical circular cylinder. In all cases, the model gives satisfactory predictions in comparison with the published analytical solutions and experimental measurements. Copyright © 2007 John Wiley and Sons, Ltd