Relative and interactive effects of plant and grazer richness in a benthic marine community

The interactive effects of changing biodiversity of consumers and their prey are poorly understood but are likely to be important under realistic scenarios of biodiversity loss and gain. We performed two factorial manipulations of macroalgal group (greens, reds, and browns) and herbivore species (amphipods, sea urchin, and fish) composition and richness in outdoor mesocosms simulating a subtidal, hard-substratum estuarine community in North Carolina, USA. In the experiment where grazer richness treatments were substitutive, there were no significant effects of algal or herbivore richness on final algal biomass. However, in the experiment in which grazer treatments were additive (i.e., species-specific densities were held constant across richness treatments), we found strong independent and interactive effects of algal and herbivore richness. Herbivore polycultures reduced algal biomass to a greater degree than the sum of the three herbivore monocultures, indicating that the measured grazer richness effects were not due solely to increased herbivore density in the polycultures. Taking grazer density into account also revealed that increasing algal richness dampened grazer richness effects. Additionally, the effect of algal richness on algal biomass accumulation was far stronger when herbivores were absent, suggesting that grazers can utilize the increased productivity and mask the positive effects of plant biodiversity on primary production. Our results highlight the complex independent and interactive effects of biodiversity between adjacent trophic levels and emphasize the importance of performing biodiversity-ecosystem functioning experiments in a realistic multi-trophic context

Preparation of GHZ states via Grover's quantum searching algorithm

In this paper we propose an approach to prepare GHZ states of an arbitrary multi-particle system in terms of Grover's fast quantum searching algorithm. This approach can be regarded as an extension of the Grover's algorithm to find one or more items in an unsorted database.Comment: 9 pages, Email address: [email protected]

(6E)-N-[(4Z)-2,5-Dimethyl-4-(p-tolyl­imino)cyclo­hexa-2,5-dienyl­idene]-4-methyl­aniline

The title compound, C22H22N2, was prepared by the reaction of 4-amino­toluene with sodium carbonate, sodium hydroxide and potassium permanganate. The mol­ecule is disposed about a crystallographic inversion centre with one half-mol­ecule comprising the asymmetric unit. The dihedral angle between the terminal and central benzene rings is 88.05 (1)°. The crystal packing is stabilized by van der Waals forces

Evaluation of range of motion restriction within the hip joint

In Total Hip Arthroplasty, determining the impingement free range of motion requirement is a complex task. This is because in the native hip, motion is restricted by both impingement as well as soft tissue restraint. The aim of this study is to determine a range of motion benchmark which can identify motions which are at risk from impingement and those which are constrained due to soft tissue. Two experimental methodologies were used to determine motions which were limited by impingement and those motions which were limited by both impingement and soft tissue restraint. By comparing these two experimental results, motions which were limited by impingement were able to be separated from those motions which were limited by soft tissue restraint. The results show motions in extension as well as flexion combined with adduction are limited by soft tissue restraint. Motions in flexion, flexion combined with abduction and adduction are at risk from osseous impingement. Consequently, these motions represent where the maximum likely damage will occur in femoroacetabular impingement or at most risk of prosthetic impingement in Total Hip Arthroplasty

Microprocessor, Setx, Xrn2, and Rrp6 Co-operate to Induce Premature Termination of Transcription by RNAPII

SummaryTranscription elongation is increasingly recognized as an important mechanism of gene regulation. Here, we show that microprocessor controls gene expression in an RNAi-independent manner. Microprocessor orchestrates the recruitment of termination factors Setx and Xrn2, and the 3′–5′ exoribonuclease, Rrp6, to initiate RNAPII pausing and premature termination at the HIV-1 promoter through cleavage of the stem-loop RNA, TAR. Rrp6 further processes the cleavage product, which generates a small RNA that is required to mediate potent transcriptional repression and chromatin remodeling at the HIV-1 promoter. Using chromatin immunoprecipitation coupled to high-throughput sequencing (ChIP-seq), we identified cellular gene targets whose transcription is modulated by microprocessor. Our study reveals RNAPII pausing and premature termination mediated by the co-operative activity of ribonucleases, Drosha/Dgcr8, Xrn2, and Rrp6, as a regulatory mechanism of RNAPII-dependent transcription elongation

Oscillations and interactions of dark and dark-bright solitons in Bose-Einstein condensates

Solitons are among the most distinguishing fundamental excitations in a wide range of non-linear systems such as water in narrow channels, high speed optical communication, molecular biology and astrophysics. Stabilized by a balance between spreading and focusing, solitons are wavepackets, which share some exceptional generic features like form-stability and particle-like properties. Ultra-cold quantum gases represent very pure and well-controlled non-linear systems, therefore offering unique possibilities to study soliton dynamics. Here we report on the first observation of long-lived dark and dark-bright solitons with lifetimes of up to several seconds as well as their dynamics in highly stable optically trapped $^{87}$Rb Bose-Einstein condensates. In particular, our detailed studies of dark and dark-bright soliton oscillations reveal the particle-like nature of these collective excitations for the first time. In addition, we discuss the collision between these two types of solitary excitations in Bose-Einstein condensates.Comment: 9 pages, 4 figure

Solving large 0–1 multidimensional knapsack problems by a new simplified binary artificial fish swarm algorithm

The artificial fish swarm algorithm has recently been emerged in continuous global optimization. It uses points of a population in space to identify the position of fish in the school. Many real-world optimization problems are described by 0-1 multidimensional knapsack problems that are NP-hard. In the last decades several exact as well as heuristic methods have been proposed for solving these problems. In this paper, a new simpli ed binary version of the artificial fish swarm algorithm is presented, where a point/ fish is represented by a binary string of 0/1 bits. Trial points are created by using crossover and mutation in the different fi sh behavior that are randomly selected by using two user de ned probability values. In order to make the points feasible the presented algorithm uses a random heuristic drop item procedure followed by an add item procedure aiming to increase the profit throughout the adding of more items in the knapsack. A cyclic reinitialization of 50% of the population, and a simple local search that allows the progress of a small percentage of points towards optimality and after that refines the best point in the population greatly improve the quality of the solutions. The presented method is tested on a set of benchmark instances and a comparison with other methods available in literature is shown. The comparison shows that the proposed method can be an alternative method for solving these problems.The authors wish to thank three anonymous referees for their comments and valuable suggestions to improve the paper. The first author acknowledges Ciˆencia 2007 of FCT (Foundation for Science and Technology) Portugal for the fellowship grant C2007-UMINHO-ALGORITMI-04. Financial support from FEDER COMPETE (Operational Programme Thematic Factors of Competitiveness) and FCT under project FCOMP-01-0124-FEDER-022674 is also acknowledged

DNA immunization as a technology platform for monoclonal antibody induction

To combat the threat of many emerging infectious diseases, DNA immunization offers a unique and powerful approach to the production of high-quality monoclonal antibodies (mAbs) against various pathogens. Compared with traditional protein-based immunization approaches, DNA immunization is efficient for testing novel immunogen designs, does not require the production or purification of proteins from a pathogen or the use of recombinant protein technology and is effective at generating mAbs against conformation-sensitive targets. Although significant progress in the use of DNA immunization to generate mAbs has been made over the last two decades, the literature does not contain an updated summary of this experience. The current review provides a comprehensive analysis of the literature, including our own work, describing the use of DNA immunization to produce highly functional mAbs, in particular, those against emerging infectious diseases. Critical factors such as immunogen design, delivery approach, immunization schedule, use of immune modulators and the role of final boost immunization are discussed in detail

Emergent global patterns of ecosystem structure and function from a mechanistic general ecosystem model

Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures

A Conserved Mechanism for Control of Human and Mouse Embryonic Stem Cell Pluripotency and Differentiation by Shp2 Tyrosine Phosphatase

Recent studies have suggested distinctive biological properties and signaling mechanisms between human and mouse embryonic stem cells (hESCs and mESCs). Herein we report that Shp2, a protein tyrosine phosphatase with two SH2 domains, has a conserved role in orchestration of intracellular signaling cascades resulting in initiation of differentiation in both hESCs and mESCs. Homozygous deletion of Shp2 in mESCs inhibited differentiation into all three germ layers, and siRNA-mediated knockdown of Shp2 expression in hESCs led to a similar phenotype of impaired differentiation. A small molecule inhibitor of Shp2 enzyme suppressed both hESC and mESC differentiation capacity. Shp2 modulates Erk, Stat3 and Smad pathways in ES cells and, in particular, Shp2 regulates BMP4-Smad pathway bi-directionally in mESCs and hESCs. These results reveal a common signaling mechanism shared by human and mouse ESCs via Shp2 modulation of overlapping and divergent pathways