Dynamic feedbacks among tree functional traits, termite populations and deadwood turnover

Changes in the composition of plant functional traits may affect ecosystem processes through influencing trophic interactions. Bottom-up control by plant species through food availability to animals may vary with time. However, such dynamics and their consequences for deadwood turnover are poorly known for detrital food webs. We introduce a dynamic conceptual model of the feedback of tree functional traits, (deadwood-feeding) termite populations and deadwood decomposition. We hypothesized that tree functional diversity (in terms of a wood resource economic spectrum [WES]) supports the sustenance of termite populations via complementary food supplied through time, as deadwood varies in traits both initially across species and because of different decomposition rates. Simultaneously, driven by this temporal dynamics of food quality, the consumption of deadwood by termites should hypothetically sustain deadwood turnover in a functionally diverse forest over time. We tested our hypothesis through an 18-month termite-exclusion decomposition experiment by incubating coarse (i.e. 5 cm diameter) deadwood of 34 woody species in two subtropical forests in East China. One site still sustained a healthy population of pangolins as the keystone termite predator, whereas another had lost its pangolins due to hunting and illegal wildlife trade. The results supported our hypothesis: in the first 12 months, termites amplified the positive linear relationship between % wood mass loss and initial wood quality (WES). In contrast, between 12 and 18 months, termite-mediated consumption, and associated wood mass loss, showed a humpback relation with the initial WES. This shift in termite preference of deadwood species along the WES reflects complementary food availability to termites through time. Synthesis. Our findings imply that tree functional composition, with variation in deadwood quality through decomposition time, can help to sustain termite populations and thereby forest carbon turnover. Future studies need to test whether and how our conceptual model may apply to other detrital systems and food webs. In general, food web research would benefit from a stronger focus on temporal patterns for better understanding the interactions of basal resource functional traits and consumers on ecosystem functions

Strong Southward Transport Events Due to Typhoons in the Taiwan Strait

Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant

Influences of the bark economics spectrum and positive termite feedback on bark and xylem decomposition

The plant economics spectrum integrates trade-offs and covariation in resource economic traits of different plant organs and their consequences for pivotal ecosystem processes, such as decomposition. However, in this concept stems are often considered as one unit ignoring the important functional differences between wood (xylem) and bark. These differences may not only affect the performance of woody plants during their lifetime, but may also have important “afterlife effects.” Specifically, bark quality may strongly affect deadwood decomposition of different woody species. We hypothesized that (1) bark quality strongly influences bark decomposability to microbial decomposers, and possibly amplifies the interspecific variation in decomposition by invertebrate consumption, especially termites; and (2) bark decomposition has secondary effects on xylem mass loss by providing access to decomposers including invertebrates such as termites. We tested these hypotheses across 34 subtropical woody species representing five common plant functional types, by conducting an in situ deadwood decomposition experiment over 12-month in two sites in subtropical evergreen broad-leaved forest in China. We employed visual examination and surface density measurement to quantify termite consumption to both bark and the underlying xylem, respectively. Using principal component analysis, we synthesized seven bark traits to provide the first empirical evidence for a bark economics spectrum (BES), with high BES values (i.e., bark thickness, nitrogen, phosphorus, and cellulose contents) indicating a resource acquisitive strategy and low BES values (i.e., carbon, lignin, and dry matter contents) indicating a resource conservative strategy. The BES affected interspecific variation in bark mass loss and this relationship was strongly amplified by termites. The BES also explained nearly half of the interspecific variation in termite consumption to xylem, making it an important contributor to deadwood decomposition overall. Moreover, the above across-species relationships manifested also within plant functional types, highlighting the value of using continuous variation in bark traits rather than categorical plant functional types in carbon cycle modeling. Our findings demonstrate the potent role of the BES in influencing deadwood decomposition including positive invertebrate feedback thereon in warm-climate forests, with implications for the role of bark quality in carbon cycling in other woody biomes

Dynamical Chiral Symmetry Breaking on the Light Front I. DLCQ Approach

Dynamical chiral symmetry breaking in the DLCQ method is investigated in detail using a chiral Yukawa model closely related to the Nambu-Jona-Lasinio model. By classically solving three constraints characteristic of the light-front formalism, we show that the chiral transformation defined on the light front is equivalent to the usual one when bare mass is absent. A quantum analysis demonstrates that a nonperturbative mean-field solution to the ``zero-mode constraint'' for a scalar boson (sigma) can develop a nonzero condensate while a perturbative solution cannot. This description is due to our identification of the ``zero-mode constraint'' with the gap equation. The mean-field calculation clarifies unusual chiral transformation properties of fermionic field, which resolves a seemingly inconsistency between triviality of the null-plane chiral charge Q_5|0>=0 and nonzero condensate. We also calculate masses of scalar and pseudoscalar bosons for both symmetric and broken phases, and eventually derive the PCAC relation and nonconservation of Q_5 in the broken phase.Comment: Revised version to appear in Phys. Rev. D. 19 pages, 4 figures, REVTEX. Derivation of the PCAC relation is given. Its relation to the nonconservation of chiral charge is clarified. 1 figure and some references adde

A Theoretical Study of the Two-Dimensional Point Focusing by Two Multilayer Laue Lenses.

Hard x-ray point focusing by two crossed multilayer Laue lenses is studied using a full-wave modeling approach. This study shows that for a small numerical aperture, the two consecutive diffraction processes can be decoupled into two independent ones in respective directions. Using this theoretical tool, we investigated adverse effects of various misalignments on the 2D focus profile and discussed the tolerance to them. We also derived simple expressions that described the required alignment accuracy

Automatic detection and repair of directive defects of Java APIs documentation

Application Programming Interfaces (APIs) represent key tools for software developers to build complex software systems. However, several studies have revealed that even major API providers tend to have incomplete or inconsistent API documentation. This can severely hamper the API comprehension and as a consequence the quality of the software built on them. In this paper, we propose DRONE (Detect and Repair of dOcumentatioN dEfects), a framework to automatically detect and repair defects from API documents by leveraging techniques from program analysis, natural language processing, and constraint solving. Specifically, we target at the directives of API documents, which are related to parameter constraints and exception handling declarations. Furthermore, in presence of defects, we also provide a prototypical repair recommendation system. We evaluate our approach on parts of the well-documented APIs of JDK 1.8 APIs (including javaFX) and Android 7.0 (level 24). Across the two empirical studies, our approach can detect API defects with an average F-measure of 79.9%, 71.7%, and 81.4%, respectively. The API repairing capability has also been evaluated on the generated recommendations in a further experiment. User judgements indicate that the constraint information is addressed correctly and concisely in the rendered directives

Play interventions to reduce anxiety and negative emotions in hospitalized children

© 2016 LI et al. Background: Hospitalization is a stressful and threatening experience, which can be emotionally devastating to children. Hospital play interventions have been widely used to prepare children for invasive medical procedures and hospitalization. Nevertheless, there is an imperative need for rigorous empirical scrutiny of the effectiveness of hospital play interventions, in particular, using play activities to ease the psychological burden of hospitalized children. This study tested the effectiveness of play interventions to reduce anxiety and negative emotions in hospitalized children. Methods: A non-equivalent control group pre-test and post-test, between subjects design was conducted in the two largest acute-care public hospitals in Hong Kong. A total of 304 Chinese children (ages 3-12) admitted for treatments in these two hospitals were invited to participate in the study. Of the 304 paediatric patients, 154 received hospital play interventions and 150 received usual care. Results: Children who received the hospital play interventions exhibited fewer negative emotions and experienced lower levels of anxiety than those children who received usual care. Conclusion: This study addressed a gap in the literature by providing empirical evidence to support the effectiveness of play interventions in reducing anxiety and negative emotions in hospitalized children. Findings from this study emphasize the significance of incorporating hospital play interventions to provide holistic and quality care to ease the psychological burden of hospitalized children. Trial registration: ClinicalTrials.gov NCT02665403. Registered 22 January 2016.published_or_final_versio

Brane fluctuation and the electroweak chiral Lagrangian

We use the external field method to study the electroweak chiral Lagrangian of the extra dimension model with brane fluctuation. Under the assumption that the contact terms between the matters of the standard model and KK excitations are heavily suppressed, we use the standard procedure to integrate out the quantum fields of KK excitations and the equation of motion to eliminate the classic fields of KK excitations. At one-loop level, we find that up to the order $O(p^4)$, due to the momentum conservation of the fifth dimension and the gauge symmetry of the zero modes, there is no constraint on the size of extra dimension. This result is consistent with the decoupling theorem. However, meaningful constraints can come from those operators in $O(p^6)$, which can contribute considerably to some anomalous vector couplings and can be accessible in the LC and LHC.Comment: Revised version, 20 pages in ReVTeX, to appear in PR