23,577 research outputs found

    An Improved molecular tool for distinguishing monoecious and dioedious Hydrilla

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    Two biotypes of hydrilla [Hydrilla verticillata(L.f.) Royle] occur in the United States, a dioecious type centered in the southeast and a monoecious type in the central Atlantic and northeastern states. Ecosystem managers need tools to distinguish the types as the ranges of each type expand and begin to overlap. A molecular tool using the randomly amplified polymorphic DNA (RAPD) procedure is available but its use is limited by a need for reference samples. We describe an alternative molecular tool which uses “universal primers” to sequence the trnL intron and trnL-F intergenic spacer of the chloroplast genome. This sequence yields three differences between the biotypes (two gaps and one single nucleotide polymorphism). A primer has been designed which ends in a gap that shows up only in the dioecious plant. A polymerase chain reaction (PCR) using this primer produces a product for the monoecious but not the dioecious plant

    Subsystem constraints in variational second order density matrix optimization: curing the dissociative behavior

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    A previous study of diatomic molecules revealed that variational second-order density matrix theory has serious problems in the dissociation limit when the N-representability is imposed at the level of the usual two-index (P, Q, G) or even three-index (T1, T2) conditions [H. van Aggelen et al., Phys. Chem. Chem. Phys. 11, 5558 (2009)]. Heteronuclear molecules tend to dissociate into fractionally charged atoms. In this paper we introduce a general class of N-representability conditions, called subsystem constraints, and show that they cure the dissociation problem at little additional computational cost. As a numerical example the singlet potential energy surface of BeB+ is studied. The extension to polyatomic molecules, where more subsystem choices can be identified, is also discussed.Comment: published version;added reference

    The COOH terminus of the c-Abl tyrosine kinase contains distinct F- and G-actin binding domains with bundling activity

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    The myristoylated form of c-Abl protein, as well as the P210bcr/abl protein, have been shown by indirect immunofluorescence to associate with F-actin stress fibers in fibroblasts. Analysis of deletion mutants of c-Abl stably expressed in fibroblasts maps the domain responsible for this interaction to the extreme COOH-terminus of Abl. This domain mediates the association of a heterologous protein with F-actin filaments after microinjection into NIH 3T3 cells, and directly binds to F-actin in a cosedimentation assay. Microinjection and cosedimentation assays localize the actin-binding domain to a 58 amino acid region, including a charged motif at the extreme COOH-terminus that is important for efficient binding. F-actin binding by Abl is calcium independent, and Abl competes with gelsolin for binding to F- actin. In addition to the F-actin binding domain, the COOH-terminus of Abl contains a proline-rich region that mediates binding and sequestration of G-actin, and the Abl F- and G-actin binding domains cooperate to bundle F-actin filaments in vitro. The COOH terminus of Abl thus confers several novel localizing functions upon the protein, including actin binding, nuclear localization, and DNA binding. Abl may modify and receive signals from the F-actin cytoskeleton in vivo, and is an ideal candidate to mediate signal transduction from the cell surface and cytoskeleton to the nucleus

    The Tragedy of the Spanish Inquisition

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    Paul van K. Thomson examines the heresies within the Church that gave rise to the various Catholic inquisitions

    Goal-directed visual attention drives health goal priming: an eye-tracking experiment

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    Objective: Several lab and field experiments have shown that goal priming interventions can be highly effective in promoting healthy food choices. Less is known, however, about the mechanisms by which goal priming affects food choice. This experiment tested the hypothesis that goal priming affects food choices through changes in visual attention. Specifically, it was hypothesized that priming with the dieting goal steers attention toward goal-relevant, low energy food products, which, in turn, increases the likelihood of choosing these products. Methods: In this eye-tracking experiment, 125 participants chose between high and low energy food products in a realistic online supermarket task while their eye movements were recorded with an eye-tracker. One group was primed with a health and dieting goal, a second group was exposed to a control prime, and a third group was exposed to no prime at all. Results: The health goal prime increased low energy food choices and decreased high energy food choices. Furthermore, the health goal prime resulted in proportionally longer total dwell times on low energy food products, and this effect mediated the goal priming effect on choices. Conclusions: The findings suggest that the effect of priming on consumer choice may originate from an increase in attention for prime-congruent items. This study supports the effectiveness of health goal priming interventions in promoting healthy eating and opens up directions for research on other behavioral interventions that steer attention toward healthy foods

    Detection of CO from SMM J16359+6612, The Multiply Imaged Submillimeter Galaxy Behind A2218

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    We report the detection of CO (JJ=3→\to2) line emission from all three multiple images (A,B and C) of the intrinsically faint (≃\simeq 0.8 mJy) submillimeter-selected galaxy SMM J16359+6612. The brightest source of the submm continuum emission (B) also corresponds to the brightest CO emission, which is centered at zz=2.5168, consistent with the pre-existing redshift derived from \Ha. The observed CO flux in the A, B and C images is 1.2, 3.5 and 1.6 Jy \kms respectively, with a linewidth of 500±100500\pm 100 \kms. After correcting for the lensing amplification, the CO flux corresponds to a molecular gas mass of ∌2×1010h71−2\sim 2\times 10 ^{10} h_{71}^{-2} \Msun, while the extent of the CO emission indicates that the dynamical mass of the system ∌9×1010\sim9\times10^{10} \Msun. Two velocity components are seen in the CO spectra; these could arise from either a rotating compact ring or disk of gas, or merging substructure. The star formation rate in this galaxy was previously derived to be ∌\sim100--500 \Msun \yr. If all the CO emission arises from the inner few kpc of the galaxy and the galactic CO-to-H2_2 conversion factor holds, then the gas consumption timescale is a relatively short 40 Myr, and so the submm emission from SMM J16359+6612 may be produced by a powerful, but short-lived circumnuclear starburst event in an otherwise normal and representative high-redshift galaxy.Comment: Appearing in the 2004 October 10 issue of the Astrophysical Journal Letters, Volume 614, L5-L

    A pilot randomised controlled trial of an internet-based cognitive behavioural therapy self-management programme (MS Invigor8) for multiple sclerosis fatigue

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    The majority of people affected by Multiple Sclerosis (PaMS) experience severe and disabling fatigue. MS Fatigue is poorly understood and most existing treatments have limited effectiveness. However, a recent randomised controlled trial (RCT) showed that cognitive-behaviour therapy with a clinical psychologist was effective in reducing MS fatigue severity and impact. The current study developed an Internet-based version of this intervention to make it available to a wider group of PaMS and conducted preliminary investigations of its efficacy, feasibility and cost-effectiveness in a pilot RCT. The ‘MS Invigor8’ website was developed using agile design and substantial input from PaMS. The programme includes eight online tailored and interactive sessions along with homework tasks, intended to be accessed weekly. In the pilot trial, 40 patients were randomised to MS Invigor8 (n=23) or standard care (n=17). The MS Invigor8 group accessed sessions over 8-10 weeks and received up to three 30-50 minute telephone support sessions. Participants completed online questionnaires assessing fatigue, mood and quality of life at baseline and 10 weeks follow-up. Large between group treatment effects were found for the primary outcomes of fatigue severity (d=1.19) and impact (d =1.22). The MS Invigor8 group also reported significantly greater improvements in anxiety and depression. Analysis suggested that the intervention may be cost-effective. Qualitative feedback suggested that participants considered this treatment approach acceptable and helpful. Technical website problems negatively affected some users’ experiences and need to be resolved. Given the promising results a larger RCT with longer term follow-up is warranted. <br/

    Disentangling causal webs in the brain using functional Magnetic Resonance Imaging: A review of current approaches

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    In the past two decades, functional Magnetic Resonance Imaging has been used to relate neuronal network activity to cognitive processing and behaviour. Recently this approach has been augmented by algorithms that allow us to infer causal links between component populations of neuronal networks. Multiple inference procedures have been proposed to approach this research question but so far, each method has limitations when it comes to establishing whole-brain connectivity patterns. In this work, we discuss eight ways to infer causality in fMRI research: Bayesian Nets, Dynamical Causal Modelling, Granger Causality, Likelihood Ratios, LiNGAM, Patel's Tau, Structural Equation Modelling, and Transfer Entropy. We finish with formulating some recommendations for the future directions in this area

    Exercise: Scenario Planning

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    Corporations operate in political, economic, and technological environments that can change rapidly. Competitive advantage can be the reward for those that anticipate, plan, and prepare for change. This exercise demonstrates the essence and value of scenario planning and enables students to experience the process of planning in volatile environments. Teams are formed, an organization is selected, and a list of strategy questions is prepared and narrowed to each team’s overriding “Big Question.” Students brainstorm a range of critical events in the competitive and general environments. Surprise is injected into the exercise by random assignment of trajectories to critical events that combine to serve as the basis for structuring a scenario. Students summarize their scenarios and prepare a strategy to capitalize on the opportunity or minimize the threat. Class presentations and discussions follow
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