Neighborhood and community interactions determine the spatial pattern of tropical tree seedling survival

Factors affecting survival and recruitment of 3531 individually mapped seedlings of Myristicaceae were examined over three years in a highly diverse neotropical rain forest, at spatial scales of 1–9 m and 25 ha. We found convincing evidence of a community compensatory trend (CCT) in seedling survival (i.e., more abundant species had higher seedling mortality at the 25-ha scale), which suggests that density-dependent mortality may contribute to the spatial dynamics of seedling recruitment. Unlike previous studies, we demonstrate that the CCT was not caused by differences in microhabitat preferences or life history strategy among the study species. In local neighborhood analyses, the spatial autocorrelation of seedling survival was important at small spatial scales (1–5 m) but decayed rapidly with increasing distance. Relative seedling height had the greatest effect on seedling survival. Conspecific seedling density had a more negative effect on survival than heterospecific seedling density and was stronger and extended farther in rare species than in common species. Taken together, the CCT and neighborhood analyses suggest that seedling mortality is coupled more strongly to the landscape-scale abundance of conspecific large trees in common species and the local density of conspecific seedlings in rare species. We conclude that negative density dependence could promote species coexistence in this rain forest community but that the scale dependence of interactions differs between rare and common species

Investigation of BOLD using CARR-PURCELL T2 Weighting with SPIRAL Readout

It is demonstrated that a Carr-Purcell (CP) technique based on the fully adiabatic pulse sequence (CP-LASER) with SPIRAL readout can be used to generate zoomed images with relatively short acquisition window (at) for the investigation of the mechanisms of the BOLD effect. Based on the capability of the developed technique to refocus the dynamic dephasing, it is demonstrated that the BOLD effect is suppressed as the pulse interval cp of CP-LASER sequence decreased

When a 520 million-year-old Chengjiang fossil meets a modern micro-CT - a case study

The 520 million-year-old Chengjiang biota of China (UNESCO World Heritage) presents the earliest known evidence of the so-called Cambrian Explosion. Studies, however, have mainly been limited to the information exposed on the surface of the slabs. Thus far, structures preserved inside the slabs were accessed by careful removal of the matrix, in many cases with the unfortunate sacrifice of some "less important" structures, which destroys elements of exceptionally preserved specimens. Here, we show for the first time that microtomography (micro-CT) can reveal structures situated inside a Chengjiang fossil slab without causing any damage. In the present study a trilobitomorph arthropod (Xandarella spectaculum) can be reliably identified only with the application of micro-CT. We propose that this technique is an important tool for studying three-dimensionally preserved Chengjiang fossils and, most likely, also those from other biota with a comparable type of preservation, specifically similar iron concentrations

Parallel Imaging with RASER using Multiband Frequency-modulated Excitation Pulses

The many advantages of the recently proposed RASER sequence have been demonstrated. Hence, RASER holds great promises for functional MRI (fMRI), particularly for studies of the orbital-frontal cortex and other brain regions near air cavities, which cause distortion and signal loss in conventional EPI methods. However, the single-shot RASER sequence implemented so far inherently presents a set of temporal and spatial limitations that hinders it feasibility and full potential for fMRI applications. It is believed that parallel imaging will help overcome such restrictions. In this work, the RASER acquisition and reconstruction scheme is extended for parallel imaging using tailored pulses for simultaneous multi-band excitation

Indoor environmental quality (IEQ) analysis of a low energy wind catcher with horizontally-arranged heat transfer devices

Windcatchers are natural ventilation systems based on the design of traditional architecture, intended to provide ventilation by manipulating pressure differentials around buildings induced by wind movement and temperature difference. Though the movement of air caused by the wind catcher will lead to a cooling sensation for occupants, the high air temperature in hot climates will result in little cooling or thermal discomfort to occupants. In order to improve the cooling performance by wind catchers, heat transfer devices were incorporated into the design. This work will investigate the indoor environment quality performance of a roof-mounted cooling windcatcher integrated with horizontally-arranged heat transfer devices (HHTD) using Computational Fluid Dynamics (CFD) and field test analysis. The windcatcher model was incorporated to a 5mx5mx3m test room model. The study employed the CFD code FLUENT with the standard k- model to conduct the steady-state RANS simulation. For the indoor CO2 concentration analysis, a simplified exhalation model was used and the room was filled with 12 occupants. The CO2 concentration analysis showed that the system was capable of delivering fresh air inside the space and lowering the CO2 levels. Thermal comfort analysis using the Predicted Mean Vote (PMV) was conducted whereby the measurements ranged from slightly-cool (-0.96) to slightly warm range (0.36 to 0.60). Field test measurements were carried out in the Ras-Al-Khaimah (RAK), UAE during the month of September. Numerical model was validated using experimental data and good agreement was observed between both methods of analysis

Protective Effects of Smoke-free Legislation on Birth Outcomes in England: A Regression Discontinuity Design

Background: Environmental tobacco smoke has an adverse impact on preterm birth and birth weight. England introduced a new law to make virtually all enclosed public places and workplaces smoke free on July 1 2007. We investigated the effect of smoke-free legislation on birth outcomes in England using Hospital Episode Statistics (HES) maternity data. Methods: We used regression discontinuity, a quasi-experimental study design, which can facilitate valid causal inference, to analyse short-term effects of smoke-free legislation on birth weight, low birth weight, gestational age, preterm birth and small for gestational age. Results: We analysed 1,800,906 pregnancies resulting in singleton live-births in England between January 1 2005 and December 31 2009. In the one to five months following the introduction of the smoking-free legislation, for those entering their third trimester, the risk of low birth weight decreased by between 8% (95% CI: 4%-12%) and 14% (95% CI: 5%-23%), very low birth weight between 28% (95% CI: 19%-36%) and 32% (95% CI: 21%-41%), preterm birth between 4% (95% CI: 1%-8%) and 9% (95% CI: 2%-16%), and small for gestational age between 5% (95% CI: 2%-8%) and 9% (95% CI: 2%-15%). The impact of the smoke-free legislation varied by maternal age, deprivation, ethnicity and region. Conclusions: The introduction of smoke-free legislation in England had an immediate beneficial impact on birth outcomes overall, although this benefit was not observed across all age, ethnic, or deprivation groups

PEDRo: A database for storing, searching and disseminating experimental proteomics data

Abstract Background Proteomics is rapidly evolving into a high-throughput technology, in which substantial and systematic studies are conducted on samples from a wide range of physiological, developmental, or pathological conditions. Reference maps from 2D gels are widely circulated. However, there is, as yet, no formally accepted standard representation to support the sharing of proteomics data, and little systematic dissemination of comprehensive proteomic data sets. Results This paper describes the design, implementation and use of a Proteome Experimental Data Repository (PEDRo), which makes comprehensive proteomics data sets available for browsing, searching and downloading. It is also serves to extend the debate on the level of detail at which proteomics data should be captured, the sorts of facilities that should be provided by proteome data management systems, and the techniques by which such facilities can be made available. Conclusions The PEDRo database provides access to a collection of comprehensive descriptions of experimental data sets in proteomics. Not only are these data sets interesting in and of themselves, they also provide a useful early validation of the PEDRo data model, which has served as a starting point for the ongoing standardisation activity through the Proteome Standards Initiative of the Human Proteome Organisation

Olfactory flow in the sea catfish, <i>Ariopsis felis</i> (L.): origin, regulation, and resampling

The olfactory epithelium of the sea catfish, Ariopsis felis, is found on a pinnate array of lamellae (the olfactory rosette) housed within a nasal chamber. The nasal anatomy of A. felis suggests an ability to capture external water currents. We prepared models from X-ray micro-computed tomography scans of two preserved specimens of A. felis. We then used dye visualisation and computational fluid dynamics to show that an external current induced a flow of water through a) the nasal chamber and b) the sensory channels of the olfactory rosette. The factors responsible for inducing flow through the nasal chamber are common to fishes from two other orders. The dye visualisation experiments, together with observations of sea catfishes in vivo, indicate that flow through the nasal chamber is regulated by a mobile nasal flap. The position of the nasal flap – elevated (significant flow) or depressed (reduced flow) – is controlled by the sea catfish’s movements. Flow in the sensory channels of the olfactory rosette can pass through either a single channel or, via multiple pathways, up to four consecutive channels. Flow through consecutive sensory channels (olfactory resampling) is more extensive at lower Reynolds numbers (200 and 300, equivalent to swimming speeds of 0.5 – 1.0 total lengths s-1), coinciding with the mean swimming speed of the sea catfishes observed in vivo (0.6 total lengths s-1). Olfactory resampling may also occur, via a vortex, within single sensory channels. In conclusion, olfactory flow in the sea catfish is regulated and thoroughly sampled by novel mechanisms