Nutrient limitation of woody debris decomposition in a tropical forest:contrasting effects of N and P addition

1.Tropical forests represent a major terrestrial store of carbon (C), a large proportion of which is contained in the soil and decaying organic matter. Woody debris plays a key role in forest C dynamics because it contains a sizeable proportion of total forest C. Understanding the factors controlling the decomposition of organic matter in general, and woody debris in particular, is hence critical to assessing changes in tropical C storage. 2.We conducted a factorial fertilization experiment in a tropical forest in South China to investigate the influence of nitrogen (N) and phosphorus (P) availability onwoody debris decomposition using branch segments (5-cm diameter) of four species (Acacia auriculaeformis, Aphanamixis polystachya, Schefflera octophylla, Carallia brachiata) in plots fertilized with +N, +P, or +NP, and controls. 3.Fertilization with +P and +NP increased decomposition rates by 5-53% and the magnitude was species-specific. Contrary to expectations, we observed no negative effect of +N addition on decay rates or mass loss of woody debris in any of the four study species. Decomposition rates of woody debris were higher in species with lower C:P ratios regardless of treatment. 4.We observed significant accumulation of P in the woody debris of all species in plots fertilized with +P and +NP during the early stages of decomposition. N-release from woody debris of Acacia (N-fixing) was greater in the +P plots towards the end of the study, whereas fertilization with +N had no impact on the patterns of nutrient release during decomposition. 5.Synthesis: Our results indicate that decomposition of woody debris is primarily constrained by P availability in this tropical forest. However, contrary to expectations, +N addition did not exacerbate P-limitation. It is conceivable that decay rates of woody debris in tropical forests can be predicted by C:P or lignin:P ratios but additional work with more tree species is needed to determine whether the patterns we observed are more generally applicable

Technology for good? Tencent’s corporate social responsibility, institutional chameleon, and the future of platform economies

There have been global regulatory debates and efforts aimed at holding digital platforms accountable for the public interest. Utilizing mixed methods of documentary research and expert interviews, this article examines how the Chinese digital giant Tencent leverages its adaptive capabilities for corporate social responsibility (CSR) initiatives in response to increasingly stringent regulation in China. Specifically, it explores Tencent’s organizational restructuring, including the establishment of the sustainable social value (SSV) division, as well as the accompanying corporate practices and discursive strategies aimed at enhancing its legitimacy. As an exemplar of the “institutional chameleon,” Tencent has deftly navigated regulatory waters through organizational metamorphosis. However, while Tencent’s enhanced CSR initiatives have certainly yielded some social benefits, the SSV initiatives are increasingly emerging as a new business frontier for the company, leveraging its vast infrastructural capacities to capitalize on the very social fabric it purports to support. This underscores the complexities and contradictions inherent in its CSR practices and the significance of the intrinsic logic of digital platforms as a modern business.</p

The impact of bank merger growth on CEO compensation

We examine the impact of bank mergers on chief executive officer (CEO) compensation during the period 1992–2014, a period characterised by significant banking consolidation. We show that CEO compensation is positively related to both merger growth and non-merger internal growth, with the former relationship being higher in magnitude. While CEO pay–risk sensitivity is not significantly related to merger growth, CEO pay–performance sensitivity is negatively and significantly related to merger growth. Collectively, our results suggest that, through bank mergers, CEOs can earn higher compensation and decouple personal wealth from bank performance. Furthermore, we document a more severe agency problem in CEO compensation as a consequence of bank mergers relative to mergers in industrial firms. Finally, we find that the post-financial crisis regulatory reform of executive compensation in banks has limited effectiveness in curbing the merger–pay links

Unification of spatiotemporal quantum formalisms: mapping between process and pseudo-density matrices via multiple-time states

We consider the relation between three different approaches to defining quantum states across several times and locations: the pseudo-density matrix (PDM), the process matrix, and the multiple-time state approaches. Previous studies have shown that bipartite two-time states can reproduce the statistics of bipartite process matrices. Here, we show that the operational scenarios underlying two-time states can be represented as PDMs, and thereby construct a mapping from process matrices to PDMs. The existence of this mapping implies that PDMs can, like the process matrix, model processes with indefinite causal orders. We illustrate this ability by showing how negativity of the PDM, a measure of temporal correlations, is activated by creating a quantum-switched order of operators associated with reset channels. The results contribute to the unification of quantum models of spatiotemporal states.Comment: 11 pages, 3 figures, Comments are welcom

Pomolic acid inhibits proliferation of human lung carcinoma cells via induction of apoptosis and suppression of cell migration and invasion

Purpose: To investigate the anti-proliferative effect of pomolic acid on lung cancer cells (A549), and theunderlying mechanism.Methods: The viability of pomolic acid-treated A549 cells was determined by MTT and colony formation assays. Cell colony formation was monitored with acridine orange/ethidium bromide (AO/EB) staining. Protein expressions of Bax and Bcl-2 were assayed by western blotting.Results: Pomolic acid suppressed the growth of A549 cells, with an half-maximal inhibitory concentration of (IC50) of 10 μM (p &lt; 0.05). However, the IC50 of pomolic acid for normal BEAS-2B cells was 80 μM. Pomolic acid also decreased colony formation of A549 cells. At 20 μM, the percentage of A549 colonies decreased to 14 % of control. The dose-dependent cytotoxicity of pomolic acid against A549 cells was mediated via induction of apoptosis and oxidative stress. Pomolic acid treatment enhanced the expression of Bax and decreased the expression of Bcl-2 in A549 cells. Moreover, pomolic acid inhibited the migration and invasion in A549 cells in a dose-dependent manner (p &lt; 0.05).Conclusion: These results indicate the potent anticancer effect of pomolic acid against human lung cancer cells. Thus, pomolic acid has promising potential as a lead molecule for the development of chemotherapy

Biomass Accumulation and Carbon Sequestration in Four Different Aged Casuarina equisetifolia Coastal Shelterbelt Plantations in South China

Thousands of kilometers of shelterbelt plantations of Casuarina equisetifolia have been planted to protect the southeast coastline of China. These plantations also play an important role in the regional carbon (C) cycling. In this study, we examined plant biomass increment and C accumulation in four different aged C. equisetifolia plantations in sandy beaches in South China. The C accumulated in the C. equisetifolia plant biomass increased markedly with stand age. The annual rate of C accumulation in the C. equisetifolia plant biomass during 0-3, 3-6, 6-13 and 13-18 years stage was 2.9, 8.2, 4.2 and 1.0 Mg C ha(-1) yr(-1), respectively. Soil organic C (SOC) at the top 1 m soil layer in these plantations was 17.74, 5.14, 6.93, and 11.87 Mg C ha(-1), respectively, with SOC density decreasing with increasing soil depth. Total C storage in the plantation ecosystem averaged 26.57, 38.50, 69.78, and 79.79 Mg C ha(-1) in the 3, 6, 13 and 18-yrs plantation, with most of the C accumulated in the aboveground biomass rather than in the belowground root biomass and soil organic C. Though our results suggest that C. equisetifolia plantations have the characteristics of fast growth, high biomass accumulation, and the potential of high C sequestration despite planting in poor soil conditions, the interactive effects of soil condition, natural disturbance, and human policies on the ecosystem health of the plantation need to be further studied to fully realize the ecological and social benefits of the C equisetifolia shelterbelt forests in South China

Low-energy spin excitations in optimally doped CaFe0.88_{0.88}Co0.12_{0.12}AsF superconductor studied with inelastic neutron scattering

There are few inelastic neutron scattering (INS) reports on the superconducting single crystals of FeAs-1111 system, even though it was first discovered in 2008, due to the extreme difficulty in large single crystal growth. In this paper, we have studied the low-energy spin excitations in the optimally electron-doped CaFe$_{0.88}$Co$_{0.12}$AsF single crystals with $T_\mathrm{c}$ = 21 K by INS. The resonance energy of the superconducting spin resonant mode with $E_\mathrm{r}$ = 12 meV amounts to 6.6 $k_\mathrm{B}$$T_\mathrm{c}$, which constitutes the largest $E_\mathrm{r}$/$k_\mathrm{B}$$T_\mathrm{c}$ ratio among iron-based superconductors reported to date. The large ratio implies a strong coupling between conduction electrons and magnetic excitations in CaFe$_{0.88}$Co$_{0.12}$AsF. The resonance possesses a magnonlike upward dispersion along transverse direction due to the anisotropy of spin-spin correlation length within $ab$ plane in the normal-state, which points to a spin fluctuation mediated sign-reversed ${s}\mathbf\pm$ wave pairing in CaFe$_{0.88}$Co$_{0.12}$AsF