No-go trials can modulate switch cost by interfering with effects of task preparation

It has recently been shown that the cost associated with switching tasks is eliminated following ‘no-go’ trials, in which response selection is not completed, suggesting that the switch cost depends on response selection. However, no-go trials may also affect switch costs by interfering with the effects of task preparation that precede response selection. To test this hypothesis we evaluated switch costs following standard go trials with those following two types of non-response trials: no-go trials, for which a stimulus is presented that indicates no response should be made (Experiment 1); and cue-only trials in which no stimulus is presented following the task cue (Experiment 2). We hypothesized that eliminating no-go stimuli would reveal effects of task preparation on the switch cost in cue-only trials. We found no switch cost following no-go trials (Experiment 1), but a reliable switch cost in cue-only trials (i.e., when no-go stimuli were removed; Experiment 2). We conclude that no-go trials can modulate the switch cost, independent of their effect on response selection, by interfering with task preparation, and that the effects of task preparation on switch cost are more directly assessed by cue-only trials

Biofabrication of Anisotropic Gold Nanotriangles Using Extract of Endophytic Aspergillus clavatus as a Dual Functional Reductant and Stabilizer

Biosynthesis of metal and semiconductor nanoparticles using microorganisms has emerged as a more eco-friendly, simpler and reproducible alternative to the chemical synthesis, allowing the generation of rare forms such as nanotriangles and prisms. Here, we report the endophytic fungus Aspergillus clavatus, isolated from surface sterilized stem tissues of Azadirachta indica A. Juss., when incubated with an aqueous solution of chloroaurate ions produces a diverse mixture of intracellular gold nanoparticles (AuNPs), especially nanotriangles (GNT) in the size range from 20 to 35 nm. These structures (GNT) are of special interest since they possess distinct plasmonic features in the visible and IR regions, which equipped them with unique physical and optical properties exploitable in vital applications such as optics, electronics, catalysis and biomedicine. The reaction process was simple and convenient to handle and was monitored using ultraviolet–visible spectroscopy (UV–vis). The morphology and crystalline nature of the GNTs were determined from transmission electron microscopy (TEM), atomic force spectroscopy (AFM) and X-ray diffraction (XRD) spectroscopy. This proposed mechanistic principal might serve as a set of design rule for the synthesis of anisotropic nanostructures with desired architecture and can be amenable for the large scale commercial production and technical applications

Gustatory Perception and Fat Body Energy Metabolism Are Jointly Affected by Vitellogenin and Juvenile Hormone in Honey Bees

Honey bees (Apis mellifera) provide a system for studying social and food-related behavior. A caste of workers performs age-related tasks: young bees (nurses) usually feed the brood and other adult bees inside the nest, while older bees (foragers) forage outside for pollen, a protein/lipid source, or nectar, a carbohydrate source. The workers' transition from nursing to foraging and their foraging preferences correlate with differences in gustatory perception, metabolic gene expression, and endocrine physiology including the endocrine factors vitellogenin (Vg) and juvenile hormone (JH). However, the understanding of connections among social behavior, energy metabolism, and endocrine factors is incomplete. We used RNA interference (RNAi) to perturb the gene network of Vg and JH to learn more about these connections through effects on gustation, gene transcripts, and physiology. The RNAi perturbation was achieved by single and double knockdown of the genes ultraspiracle (usp) and vg, which encode a putative JH receptor and Vg, respectively. The double knockdown enhanced gustatory perception and elevated hemolymph glucose, trehalose, and JH. We also observed transcriptional responses in insulin like peptide 1 (ilp1), the adipokinetic hormone receptor (AKHR), and cGMP-dependent protein kinase (PKG, or “foraging gene” Amfor). Our study demonstrates that the Vg–JH regulatory module controls changes in carbohydrate metabolism, but not lipid metabolism, when worker bees shift from nursing to foraging. The module is also placed upstream of ilp1, AKHR, and PKG for the first time. As insulin, adipokinetic hormone (AKH), and PKG pathways influence metabolism and gustation in many animals, we propose that honey bees have conserved pathways in carbohydrate metabolism and conserved connections between energy metabolism and gustatory perception. Thus, perhaps the bee can make general contributions to the understanding of food-related behavior and metabolic disorders

A Meta-Analysis of Probiotic Efficacy for Gastrointestinal Diseases

Background: Meta-analyses on the effects of probiotics on specific gastrointestinal diseases have generally shown positive effects on disease prevention and treatment; however, the relative efficacy of probiotic use for treatment and prevention across different gastrointestinal diseases, with differing etiology and mechanisms of action, has not been addressed. Methods/Principal Findings: We included randomized controlled trials in humans that used a specified probiotic in the treatment or prevention of Pouchitis, Infectious diarrhea, Irritable Bowel Syndrome, Helicobacter pylori, Clostridium difficile Disease, Antibiotic Associated Diarrhea, Traveler’s Diarrhea, or Necrotizing Enterocolitis. Random effects models were used to evaluate efficacy as pooled relative risks across the eight diseases as well as across probiotic species, single vs. multiple species, patient ages, dosages, and length of treatment. Probiotics had a positive significant effect across all eight gastrointestinal diseases with a relative risk of 0.58 (95 % (CI) 0.51–0.65). Six of the eight diseases: Pouchitis, Infectious diarrhea, Irritable Bowel Syndrome, Helicobacter pylori, Clostridium difficile Disease, and Antibiotic Associated Diarrhea, showed positive significant effects. Traveler’s Diarrhea and Necrotizing Enterocolitis did not show significant effects of probiotcs. Of the 11 species and species mixtures, all showed positive significant effects except for Lactobacillus acidophilus, Lactobacillus plantarum, and Bifidobacterium infantis. Across all diseases and probiotic species, positive significant effects of probiotics were observed for all age groups, single vs. multiple species, and treatment lengths

Metagenomics of the Deep Mediterranean, a Warm Bathypelagic Habitat

BACKGROUND: Metagenomics is emerging as a powerful method to study the function and physiology of the unexplored microbial biosphere, and is causing us to re-evaluate basic precepts of microbial ecology and evolution. Most marine metagenomic analyses have been nearly exclusively devoted to photic waters. METHODOLOGY/PRINCIPAL FINDINGS: We constructed a metagenomic fosmid library from 3,000 m-deep Mediterranean plankton, which is much warmer (approximately 14 degrees C) than waters of similar depth in open oceans (approximately 2 degrees C). We analyzed the library both by phylogenetic screening based on 16S rRNA gene amplification from clone pools and by sequencing both insert extremities of ca. 5,000 fosmids. Genome recruitment strategies showed that the majority of high scoring pairs corresponded to genomes from Rhizobiales within the Alphaproteobacteria, Cenarchaeum symbiosum, Planctomycetes, Acidobacteria, Chloroflexi and Gammaproteobacteria. We have found a community structure similar to that found in the aphotic zone of the Pacific. However, the similarities were significantly higher to the mesopelagic (500-700 m deep) in the Pacific than to the single 4000 m deep sample studied at this location. Metabolic genes were mostly related to catabolism, transport and degradation of complex organic molecules, in agreement with a prevalent heterotrophic lifestyle for deep-sea microbes. However, we observed a high percentage of genes encoding dehydrogenases and, among them, cox genes, suggesting that aerobic carbon monoxide oxidation may be important in the deep ocean as an additional energy source. CONCLUSIONS/SIGNIFICANCE: The comparison of metagenomic libraries from the deep Mediterranean and the Pacific ALOHA water column showed that bathypelagic Mediterranean communities resemble more mesopelagic communities in the Pacific, and suggests that, in the absence of light, temperature is a major stratifying factor in the oceanic water column, overriding pressure at least over 4000 m deep. Several chemolithotrophic metabolic pathways could supplement organic matter degradation in this most depleted habitat

Transcriptome Analysis of the Desert Locust Central Nervous System: Production and Annotation of a Schistocerca gregaria EST Database

) displays a fascinating type of phenotypic plasticity, designated as ‘phase polyphenism’. Depending on environmental conditions, one genome can be translated into two highly divergent phenotypes, termed the solitarious and gregarious (swarming) phase. Although many of the underlying molecular events remain elusive, the central nervous system (CNS) is expected to play a crucial role in the phase transition process. Locusts have also proven to be interesting model organisms in a physiological and neurobiological research context. However, molecular studies in locusts are hampered by the fact that genome/transcriptome sequence information available for this branch of insects is still limited. EST information is highly complementary to the existing orthopteran transcriptomic data. Since many novel transcripts encode neuronal signaling and signal transduction components, this paper includes an overview of these sequences. Furthermore, several transcripts being differentially represented in solitarious and gregarious locusts were retrieved from this EST database. The findings highlight the involvement of the CNS in the phase transition process and indicate that this novel annotated database may also add to the emerging knowledge of concomitant neuronal signaling and neuroplasticity events. EST data constitute an important new source of information that will be instrumental in further unraveling the molecular principles of phase polyphenism, in further establishing locusts as valuable research model organisms and in molecular evolutionary and comparative entomology

Synthesis, reactivity, and computational studies of the cationic tungsten methyl complex [W(NPh)(N2Npy)Me](+) and related compounds (N2Npy = MeC(2-C5H4N)(CH2NSiMe3)(2))

The synthesis and structure of neutral and cationic tungsten methyl complex was analyzed. The site preferences for the imido and methyl ligands in 2+ and related species were rationalized in terms of π-bonding preferences modified by steric influences. Inclusion of the steric bulk of the silicon manganese groups and the R group on the imido ligand showed that the underlying electronic preference for the imido ligand to be trans to pyridyl can be reversed because of increased steric repulsions. It was observed that increase in steric repulsions caused a misdirection of the amido lone pair π-donation, which in turn destabilizes the metal-imido ligand π-bonding

Reactions of neutral and cationic diamide-supported imido complexes with CO2 and other heterocumulenes: Issues of site selectivity

Experimental and DFT computational studies of the reactions of the cationic diamide-pyridine-supported methyl tungsten complex [W(NPh)(N3N py)Me]+ (2+) with the heterocumulenes CO 2, CS2, RNCO, and RNCS (R = tert-butyl or aryl) are described, together with comparative studies of the group 5 compounds M(N tBu)(N2Npy)Cl(py) (M = Nb (13) or Ta (14)) and Ta(NtBu)(N2Npy)Me (N2Npy = McC(2-C5H4N)(CH2NSiMe3) 2). In all of the reactions of 2+ the heterocumulene inserted exclusively into a W-Namide bond to give unstable intermediates (isolated for certain isocyanate substrates), which subsequently underwent rearrangement via a 1,3-migration of a SiMe3 group. DFT studies of the reaction of 2+ with CO2 showed that insertion into the W-Me bond is in fact thermodynamically preferred, but that insertion into W-Namide is kinetically more facile. Cycloaddition to the W=NPh bond was neither kinetically nor thermodynamically viable. The reactions between Ta(NtBu)-(N2Npy)Me and CO2 or RNCO in contrast gave complex mixtures, as did those between 13 and 14 and CO2. DFT studies showed that in a neutral but otherwise identical tantalum analogue of 2+ the preference for substrate attack at the M-Namide bond is much less pronounced. Reactions of 13 and 14 with the more sterically discriminating RNCO (R = tBu or p-tolyl) did, however, exclusively afford M-Namide insertion/l,3-SiMe3 migration products, and Nb(NtBu) {MeC(2-C5H4N)(CH2NSiMe3)(CH 2NC(OSiMe3)NtBu)}Cl was structurally characterized. The previously reported reaction of Ti(NtBu)(N 2Npy)(py) with ArNCO (Ar = 2,6-C6H 3iPr2) was re-evaluated and shown to involve an analogous Ti-Namide insertion/1,3-SiMe3 migration reaction, ultimately forming Ti(NtBu){McC(2-C5H4N) (CH2NSiMe3)(CH2NC(N(Ar)-SiMe 3)O)}(py). © 2005 American Chemical Society

Digital Image Segmentation for Cardiac Medical Images

Abstract—The digital image processing has proved beneficial in different areas. It is used as an appliance for extraction of a desired part of an image. At beginning, segmentation is performed on interested part of an image whose result can be used as a reference for different study. Different segmentation methods are present to perform this task, but the project aims at finding such a method which can be abundant for better segmentation. The proposed method revolves around selection of threshold value using techniques like histogram quantization, analysing of histogram slope percentage and determining of maximum entropy value. The result are luminous when a noise reduced image is used for segmentation. Keywords—Entropy, cardiac Images, segmentation, threshold, histogram. However, this method is ineffective when the image is distorted with elements like noise, white-spots, etc. Thus, in this context, if we previously perform noise reduction technique on the image and then provide it as an input, then a better result is obtained. To calculate multilevel threshold values, the techniques used are grouping of gray-level values, plotting of the histogram and calculation of maximum entropy. These technique clearly identifies insignificant thresholds and enables us to have control over the feature extraction process. II. ARCHITECTURE I