96 research outputs found

    Extreme longevity of the common gecko (Hoplodactylus maculatus) on Motunau Island, Canterbury, New Zealand

    Get PDF
    The longevity of common geckos (Hoplodactylus maculatus) on predator-free Motunau Island, North Canterbury, was investigated. Sixteen of 133 individuals marked between 1967-75 were re-captured in the summer of 1996/97. A growth curve was generated to estimate the age of these geckos at first capture, and from this their age in 1996/97; 10 were estimated to be at least 36 years old. In this cool-temperate habitat, H. maculatus matures late and has a low annual reproductive output over an extended lifespan. This suggests that nearby mainland populations would be particularly slow to recover from the impacts of introduced mammalian predators

    Bright conjugated polymer nanoparticles containing a biodegradable shell produced at high yields and with tuneable optical properties by a scalable microfluidic device

    Get PDF
    This study compares the performance of a microfluidic technique and a conventional bulk method to manufacture conjugated polymer nanoparticles (CPNs) embedded within a biodegradable poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG5K–PLGA55K) matrix. The influence of PEG5K–PLGA55K and conjugated polymers cyano-substituted poly(p-phenylene vinylene) (CN-PPV) and poly(9,9-dioctylfluorene-2,1,3-benzothiadiazole) (F8BT) on the physicochemical properties of the CPNs was also evaluated. Both techniques enabled CPN production with high end product yields (?70–95%). However, while the bulk technique (solvent displacement) under optimal conditions generated small nanoparticles (∌70–100 nm) with similar optical properties (quantum yields ∌35%), the microfluidic approach produced larger CPNs (140–260 nm) with significantly superior quantum yields (49–55%) and tailored emission spectra. CPNs containing CN-PPV showed smaller size distributions and tuneable emission spectra compared to F8BT systems prepared under the same conditions. The presence of PEG5K–PLGA55K did not affect the size or optical properties of the CPNs and provided a neutral net electric charge as is often required for biomedical applications. The microfluidics flow-based device was successfully used for the continuous preparation of CPNs over a 24 hour period. On the basis of the results presented here, it can be concluded that the microfluidic device used in this study can be used to optimize the production of bright CPNs with tailored properties with good reproducibility

    Salmonella Infection Drives Promiscuous B Cell Activation Followed by Extrafollicular Affinity Maturation

    Get PDF
    SummaryThe B cell response to Salmonella typhimurium (STm) occurs massively at extrafollicular sites, without notable germinal centers (GCs). Little is known in terms of its specificity. To expand the knowledge of antigen targets, we screened plasmablast (PB)-derived monoclonal antibodies (mAbs) for Salmonella specificity, using ELISA, flow cytometry, and antigen microarray. Only a small fraction (0.5%–2%) of the response appeared to be Salmonella-specific. Yet, infection of mice with limited B cell receptor (BCR) repertoires impaired the response, suggesting that BCR specificity was important. We showed, using laser microdissection, that somatic hypermutation (SHM) occurred efficiently at extrafollicular sites leading to affinity maturation that in turn led to detectable STm Ag-binding. These results suggest a revised vision of how clonal selection and affinity maturation operate in response to Salmonella. Clonal selection initially is promiscuous, activating cells with virtually undetectable affinity, yet SHM and selection occur during the extrafollicular response yielding higher affinity, detectable antibodies

    Small and medium-sized enterprise policy: Designed to fail?

    Get PDF
    Significant doubts persist over the effectiveness of government policy to increase the numbers or performance of small and medium-sized enterprises in the UK economy. We analyse UK political manifestoes from 1964-2015 to examine the development of SME policy in political discourse. We do this by analysing how the broadly-defined category of ‘SME’ has been characterised in the manifestoes and assess these characterisations in relation to the empirical evidence base. We highlight three consistent themes in UK political manifestoes during 1964-2015 where SMEs have been characterised as having the potential for growth, struggling to access finance and being over-burdened by regulation. We argue that homogenising the broad range of businesses represented by the SME category and characterising them in these terms misrepresents them, undermining policies developed in relation to this mischaracterisation

    Determinants of Cross-Border M&As and Shareholder Wealth Effects in a Globalized World

    Get PDF
    We analyze theoretical insights and empirical regularities related to factors determining the cross-border mergers and acquisitions (M&As) and impact of M&As on shareholder value of acquires and targets. The analysis of cross-border M&As is a relatively new subject and only recently received rigorous attention in academic research. Within this nascent literature, the survey pays particular attention to the emerging markets, which, in line with their growing role of in the global economy, became an increasingly important arena for cross-border M&As. The existing evidence point out to prevailing challenges in studying cross-border M&As by emerging markets firms. The results are often contradictory and tend to focus on a single country falling short of formally testing existing theories or developing comprehensive theories for emerging economies. We show that the type of factors increasing the value enhancing effects of M&As tends to be similar to the factors affecting the likelihood of M&As transactions. The remaining methodological challenges for the existing studies are related to strong evidence with respect to nonrandom selection of acquisition targets, which, among other “selection issues,” has important implications for choosing counterfactual evidence in order to appropriately compare pre- and postacquisition performance of firms

    The ineffectiveness of entrepreneurship policy:Is policy formulation to blame?

    Get PDF
    Entrepreneurship policy has been criticised for its lack of effectiveness. Some scholars, such as Scott Shane in this journal, have argued that it is ‘bad’ public policy. But this simply begs the question why the legislative process should generate bad policy? To answer this question this study examines the UK’s enterprise policy process in the 2009–2010 period. It suggests that a key factor for the ineffectiveness of policy is how it is formulated. This stage in the policy process is seldom visible to those outside of government departments and has been largely ignored by prior research. The application of institutional theory provides a detailed theoretical understanding of the actors and the process by which enterprise policy is formulated. We find that by opening up the ‘black box’ of enterprise policy formulation, the process is dominated by powerful actors who govern the process with their interests

    International Society of Sports Nutrition Position Stand: Probiotics.

    Get PDF
    Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows: 1)Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO).2)Probiotic administration has been linked to a multitude of health benefits, with gut and immune health being the most researched applications.3)Despite the existence of shared, core mechanisms for probiotic function, health benefits of probiotics are strain- and dose-dependent.4)Athletes have varying gut microbiota compositions that appear to reflect the activity level of the host in comparison to sedentary people, with the differences linked primarily to the volume of exercise and amount of protein consumption. Whether differences in gut microbiota composition affect probiotic efficacy is unknown.5)The main function of the gut is to digest food and absorb nutrients. In athletic populations, certain probiotics strains can increase absorption of key nutrients such as amino acids from protein, and affect the pharmacology and physiological properties of multiple food components.6)Immune depression in athletes worsens with excessive training load, psychological stress, disturbed sleep, and environmental extremes, all of which can contribute to an increased risk of respiratory tract infections. In certain situations, including exposure to crowds, foreign travel and poor hygiene at home, and training or competition venues, athletes' exposure to pathogens may be elevated leading to increased rates of infections. Approximately 70% of the immune system is located in the gut and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.7)Intense, prolonged exercise, especially in the heat, has been shown to increase gut permeability which potentially can result in systemic toxemia. Specific probiotic strains can improve the integrity of the gut-barrier function in athletes.8)Administration of selected anti-inflammatory probiotic strains have been linked to improved recovery from muscle-damaging exercise.9)The minimal effective dose and method of administration (potency per serving, single vs. split dose, delivery form) of a specific probiotic strain depends on validation studies for this particular strain. Products that contain probiotics must include the genus, species, and strain of each live microorganism on its label as well as the total estimated quantity of each probiotic strain at the end of the product's shelf life, as measured by colony forming units (CFU) or live cells.10)Preclinical and early human research has shown potential probiotic benefits relevant to an athletic population that include improved body composition and lean body mass, normalizing age-related declines in testosterone levels, reductions in cortisol levels indicating improved responses to a physical or mental stressor, reduction of exercise-induced lactate, and increased neurotransmitter synthesis, cognition and mood. However, these potential benefits require validation in more rigorous human studies and in an athletic population

    International Society of Sports Nutrition Position Stand: Nutritional recommendations for single-stage ultra-marathon; training and racing

    Get PDF
    Background. In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~60% of energy intake, 5 – 8 gâž±kg−1·d−1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~1.6 g·kg−1·d−1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 gâž±kg−1·d−1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150 - 400 kcalâž±h−1 (carbohydrate, 30 – 50 gâž±h−1; protein, 5 – 10 gâž±h−1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450 – 750 mLâž±h−1 (~150 – 250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., >575 mg·L−1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety
    • 

    corecore