3,444 research outputs found

    Fear and its implications for stock markets

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    The value of stocks, indices and other assets, are examples of stochastic processes with unpredictable dynamics. In this paper, we discuss asymmetries in short term price movements that can not be associated with a long term positive trend. These empirical asymmetries predict that stock index drops are more common on a relatively short time scale than the corresponding raises. We present several empirical examples of such asymmetries. Furthermore, a simple model featuring occasional short periods of synchronized dropping prices for all stocks constituting the index is introduced with the aim of explaining these facts. The collective negative price movements are imagined triggered by external factors in our society, as well as internal to the economy, that create fear of the future among investors. This is parameterized by a ``fear factor'' defining the frequency of synchronized events. It is demonstrated that such a simple fear factor model can reproduce several empirical facts concerning index asymmetries. It is also pointed out that in its simplest form, the model has certain shortcomings.Comment: 5 pages, 5 figures. Submitted to the Proceedings of Applications of Physics in Financial Analysis 5, Turin 200

    A Review of Biotechnological Artemisinin Production in Plants

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    Malaria is still an eminent threat to major parts of the world population mainly in sub-Saharan Africa. Researchers around the world continuously seek novel solutions to either eliminate or treat the disease. Artemisinin, isolated from the Chinese medicinal herb Artemisia annua, is the active ingredient in artemisinin-based combination therapies used to treat the disease. However, naturally artemisinin is produced in small quantities, which leads to a shortage of global supply. Due to its complex structure, it is difficult chemically synthesize. Thus to date, A. annua remains as the main commercial source of artemisinin. Current advances in genetic and metabolic engineering drives to more diverse approaches and developments on improving in planta production of artemisinin, both in A. annua and in other plants. In this review, we describe efforts in bioengineering to obtain a higher production of artemisinin in A. annua and stable heterologous in planta systems. The current progress and advancements provides hope for significantly improved production in plants

    Synchronization Model for Stock Market Asymmetry

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    The waiting time needed for a stock market index to undergo a given percentage change in its value is found to have an up-down asymmetry, which, surprisingly, is not observed for the individual stocks composing that index. To explain this, we introduce a market model consisting of randomly fluctuating stocks that occasionally synchronize their short term draw-downs. These synchronous events are parameterized by a ``fear factor'', that reflects the occurrence of dramatic external events which affect the financial market.Comment: 4 pages, 4 figure

    Four complete genome sequences for Bradyrhizobium sp. strains isolated from an endemic Australian Acacia legume reveal structural variation

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    Bradyrhizobium sp. strains were isolated from root nodules of the Australian legume, Acacia acuminata (Fabaceae). Here, we report the complete genome sequences of four strains using a hybrid long- and short-read assembly approach. The genome sizes range between;7.1Mbp and;8.1Mbp, each with one single circular chromosome. Whole-genome alignments show extensive structural rearrangement

    Dietary modifiers of carcinogenesis.

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    Dietary components express a wide range of activities that can affect carcinogenesis. Naturally occurring substances in foods have been shown in laboratory experiments to serve as dietary antimutagens, either as bioantimutagens or as desmutagens. Dietary desmutagens may function as chemical inactivaters, enzymatic inducers, scavengers, or antioxidants. Dietary components may also act later in the carcinogenic process as tumor growth suppressors. Examples of dietary factors acting in each of these stages of carcinogenesis are presented, and potential anticarcinogens such as the carotenoids, tocopherols, phenolic compounds, glucosinolates, metal-binding proteins, phytoestrogens, and conjugated linoleic acid are discussed. Individual foods typically contain multiple potential anticarcinogens. Many of these substances can influence carcinogenesis through more than one mechanism. Some substances exhibit both anticarcinogenic and carcinogenic activity in vitro, depending on conditions. Epidemiologic research indicates that high fruit and vegetable consumption is associated with lower cancer risk. Little research has focused on the effects of single substances or single foods in man. Realization of the potential of foodborne substances to reduce the human burden of cancer will only be achieved with better measurement of dietary exposures and funding of multidisciplinary research in this area commensurate with its importance

    Implementation of Web-based Information Systems in Distributed Organizations: A Change Management Approach

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    This article presents results elicited from studies conducted in relation to implementing a web-based information system throughout a large distributed organization. We demonstrate the kind of expectations and conditions for change that management face in relation to open-ended, configurable, and context specific web-based information systems like Lotus QuickPlace. Our synthesis from the empirical findings is related to two recent models, the improvisational change management model suggested by Orlikowski and Hofman (1997), and Gallivan’s (2001) model for organizational adoption and assimilation. In line with comparable approaches from the knowledge management area (Dixon 2000; Markus 2001), we relate to, refine, and operationalize the models from an overall organizational view by identifying and characterizing four different and general implementation contexts

    KINETICS AND ELECTROMYOGRAPHY OF THE MARTIAL ARTS HIGH FRONT KICK

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    INTRODUCTION Fast unloaded movements like striking, throwing and kicking are typically performed in a proximo-distal sequence: Initially proximal segments accelerate while distal segments lag behind, then proximal segments deceler- ate while distal segments accelerate. In kicking, for instance, it is observed that the movement starts with forward angular acceleration of the thigh while the shank lags behind. Then the thigh decelerates while simultaneously the shank accelerates and the foot reaches its maximal velocity. This raises two questions: Is the thigh actively decelerated by the glutei and/or hamstring muscles, or passively decelerated by joint reaction forces from the accelerating shank7 Is acceleration of the shank enhanced by the thigh's deceleration? From a kinematic perspective this movement coordination seems disadvantageous, considering that the resulting linear velocity of the foot relative to the ground equals the vector sum of the resulting linear velocity of the knee relative to the ground and the foot relative to the knee. However, from a kinetic perspective it can be argued that thigh deceleration enhances shah acceleration to a degree where toss of knee velocity is more than accounted for in gain of foot velocity. The theory is that the angularly decelerating thigh exerts a knee joint force which causes angular acceleration of the shank, i.e. a %hip-lash" action. To obtain knowledge regarding how these kinds of movements are performed we decided to examine the martial arts high front kick. Similar to previous kicking studies we did so by kinematic measurements but in addition recorded the electrical activity of selected muscles in order to asses their temporal activation during the kick. METHODS Seventeen skilled taekwondo practitioners (14 males. 3 females) volunteered to take part in this study. Each subject performed three high front kicks aiming at a tennis ball suspended from the ceiling and adjusted to chin level. The fastest kick from each subject was selected for further analysis. The subjects were high speed filmed (200 f.p.s.) from their right side while kicking. Contrasting markers on selected anatomical landmarks enabled subsequent automatic digitisation. Displacement data were lowpass filtered with optimal cut-off frequencies (6-1 0 Hz) determined by use of residual analysis/ Jackson Knee method. Velocities and accelerations were derived from the displacement data by finite difference calculation. During kicking the electtomyographic activity (EMG) from five selected leg muscles were measured with surface electrodes. Kinetic data were obtained through inverse dynamics calculation using a two-segment link-segment model of the kicking leg and the movement equations developed by Putnam (1983). These equations enable division of the resulting moment acting on a segment into muscular components and motion de- pendant components arising from movement of adjacent segments. RESULTS Data for the thigh indicated that deceleration was caused by motion dependant moments arising from shank motion and not by active hip extensor muscles. Shank acceleration was caused partly by a knee extensor muscle moment and partly by a motion dependant moment arising from thigh angular velocity. Both thigh and shank kinetics were supported by EMG recordings. CONCLUSION As part of the accelerating moment acting on the shank was due to thigh angular velocity we suggest that the observed thigh deceleration should be considered unwanted but unavoidable due to shank acceleration. This implies that even though knee extensor muscles are important for shank acceleration the hip flexor muscles must not be neglected

    The Amazon Flood Plain Forest Tree Maquira coriacea (Karsten) C.C. Berg: Aspects of Ecology and Management

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    Maquira coriacea is a commercial tree species growing throughout the Amazon flood plain forests. Densities up to 14/ha of individuals, >10 cm diameter at breast height (DBH) were observed, corresponding to a basal area of 2 m2/ha and a volume of 38 m3/ha. The primary period of fruiting coincided with the annual flooding, but fruits were also produced in other parts of the year. Seedlings with densities up to 150/m2 were concentrated around mother trees, and the stocks fluctuated much over the year due to mortality caused by flooding and wilting in dry periods. Growth data mainly from nine 1 ha permanent sample plots were used to develop models of the height-diameter relationship and diameter increment. These relationships indicated that the optimal felling limit for maximum volume production was 120-130 cm DBH, which can be obtained in 150-260 years. Since seed production has been observed in much smaller individuals, such diameter limits should not be detrimental to regeneration

    The Case for an Accelerating Universe from Supernovae

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    The unexpected faintness of high-redshift Type Ia supernovae (SNe Ia), as measured by two teams, has been interpreted as evidence that the expansion of the Universe is accelerating. We review the current challenges to this interpretation and seek to answer whether the cosmological implications are compelling. We discuss future observations of SNe Ia which could offer extraordinary evidence to test acceleration.Comment: To appear as an Invited Review for PASP 20 pages, 13 figure

    Medical Countermeasures for Radiation Induced Health Effects: Reports of an Interagency Panel Session Held at the NASA Human Research Program Investigator's Workshop, January 26, 2017

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    An Interagency Panel Session organized by the NASA Human Research Program Space Radiation Program Element (SRPE) was held during the NASA Human Research Program (HRP) Investigators Workshop (IWS) in Galveston, Texas on January 26, 2017 to identify complementary research areas that will advance the testing and development of medical countermeasures (MCM) in support of radioprotection and radiation mitigation on the ground and in space. There were several areas of common interest identified among the various participating agencies. This report provides a summary of the topics discussed by each agency along with potential areas of intersection for mutual collaboration opportunities. Common goals included repurposing of pharmaceuticals, neutraceuticals for use as radioprotectors and/or mitigators, low-dose/chronic exposure paradigms, late effects post-radiation exposure, mixed-field exposures of gamma-neutron, performance decrements, and methods to determine individual exposure levels
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