2,420 research outputs found
Entry in the ADHD drugs market: Welfare impact of generics and me-toos
Recent decades have seen a growth in treatments for attention deficit hyperactivity disorder (ADHD) including many branded and generic drugs. In the early 2000's, new drug entry dramatically altered market shares. We estimate a demand system for ADHD drugs and assess the welfare impact of new drugs. We find that entry induced large welfare gains by reducing prices of substitute drugs, and by providing alternative delivery mechanisms for existing molecules. Our results suggest that the success of follow-on patented drugs may come from unanticipated innovations like delivery mechanisms, a factor ignored by proposals to retard new follow-on drug approvals
Visualising Silicon in Plants: Histochemistry, Silica Sculptures and Elemental Imaging.
Silicon is a non-essential element for plants and is available in biota as silicic acid. Its presence has been associated with a general improvement of plant vigour and response to exogenous stresses. Plants accumulate silicon in their tissues as amorphous silica and cell walls are preferential sites. While several papers have been published on the mitigatory effects that silicon has on plants under stress, there has been less research on imaging silicon in plant tissues. Imaging offers important complementary results to molecular data, since it provides spatial information. Herein, the focus is on histochemistry coupled to optical microscopy, fluorescence and scanning electron microscopy of microwave acid extracted plant silica, techniques based on particle-induced X-ray emission, X-ray fluorescence spectrometry and mass spectrometry imaging (NanoSIMS). Sample preparation procedures will not be discussed in detail, as several reviews have already treated this subject extensively. We focus instead on the information that each technique provides by offering, for each imaging approach, examples from both silicifiers (giant horsetail and rice) and non-accumulators (Cannabis sativa L.)
Lunar mission safety and rescue Midterm presentation, Nov. 1970
Discussing major and minor tasks of safety and rescue planning for lunar mission
Common Causes and The Direction of Causation
Is the common cause principle merely one of a set of useful heuristics for discovering causal relations, or is it rather a piece of heavy duty metaphysics, capable of grounding the direction of causation itself? Since the principle was introduced in Reichenbachâs groundbreaking work The Direction of Time (1956), there have been a series of attempts to pursue the latter programâto take the probabilistic relationships constitutive of the principle of the common cause and use them to ground the direction of causation. These attempts have not all explicitly appealed to the principle as originally formulated; it has also appeared in the guise of independence conditions, counterfactual overdetermination, and, in the causal modelling literature, as the causal markov condition. In this paper, I identify a set of difficulties for grounding the asymmetry of causation on the principle and its descendents. The first difficulty, concerning what I call the vertical placement of causation, consists of a tension between considerations that drive towards the macroscopic scale, and considerations that drive towards the microscopic scaleâthe worry is that these considerations cannot both be comfortably accommodated. The second difficulty consists of a novel potential counterexample to the principle based on the familiar Einstein Podolsky Rosen (EPR) cases in quantum mechanics
The new very small angle neutron scattering spectrometer at Laboratoire Leon Brillouin
The design and characteristics of the new very small angle neutron scattering
spectrometer under construction at the Laboratoire Leon Brillouin is described.
Its goal is to extend the range of scattering vectors magnitudes towards
2x10{-4} /A. The unique feature of this new spectrometer is a high resolution
two dimensional image plate detector sensitive to neutrons. The wavelength
selection is achieved by a double reflection supermirror monochromator and the
collimator uses a novel multibeam design
Assessment of Connections Between Knowledge- Based Economy Characteristics and Selected Macroeconomic Categories in the European Union's Countries by Means of Panel Models
The aim of the article is to analyze the impact of knowledge-based economy variables on the selected macroeconomic categories - the share of total investments in GDP and the employment rate- in European Union's countries in the years 2000-2007, conducted with application of panel models.Celem artykuĹu jest analiza wpĹywu zmiennych opisujÄ
cych gospodarkÄ opartÄ
na wiedzy na podstawowe kategorie makroekonomiczne - udziaĹ caĹkowitych inwestycji w PKB i stopÄ zatrudnienia - w krajach Unii Europejskiej (z podziaĹem na kraje UE-15 i nowe kraje czĹonkowskie UE) w latach 2000-2007, przeprowadzona w oparciu o modele panelowe
Plant Extracellular Vesicles and Nanovesicles: Focus on Secondary Metabolites, Proteins and Lipids with Perspectives on Their Potential and Sources
While human extracellular vesicles (EVs) have attracted a big deal of interest and have been extensively characterized over the last years, plant-derived EVs and nanovesicles have earned less attention and have remained poorly investigated. Although a series of investigations already revealed promising beneficial health effects and drug delivery properties, adequate (pre)clinical studies are rare. This fact might be caused by a lack of sources with appropriate qualities. Our study introduces plant cell suspension culture as a new and well controllable source for plant EVs. Plant cells, cultured in vitro, release EVs into the growth medium which could be harvested for pharmaceutical applications. In this investigation we characterized EVs and nanovesicles from distinct sources. Our findings regarding secondary metabolites indicate that these might not be packaged into EVs in an active manner but enriched in the membrane when lipophilic enough, since apparently lipophilic compounds were associated with nanovesicles while more hydrophilic structures were not consistently found. In addition, protein identification revealed a possible explanation for the mechanism of EV cell wall passage in plants, since cell wall hydrolases like 1,3-β-glucosidases, pectinesterases, polygalacturonases, β-galactosidases and β-xylosidase/ι-L-arabinofuranosidase 2-like are present in plant EVs and nanovesicles which might facilitate cell wall transition. Further on, the identified proteins indicate that plant cells secrete EVs using similar mechanisms as animal cells to release exosomes and microvesicles
Biochemical and cytological interactions between callose synthase and microtubules in the tobacco pollen tube
Key message: The article concerns the association between callose synthase and cytoskeleton by biochemical and ultrastructural analyses in the pollen tube. Results confirmed this association and immunogold labeling showed a colocalization. Abstract: Callose is a cell wall polysaccharide involved in fundamental biological processes, from plant development to the response to abiotic and biotic stress. To gain insight into the deposition pattern of callose, it is important to know how the enzyme callose synthase is regulated through the interaction with the vesicle-cytoskeletal system. Actin filaments likely determine the long-range distribution of callose synthase through transport vesicles but the spatial/biochemical relationships between callose synthase and microtubules are poorly understood, although experimental evidence supports the association between callose synthase and tubulin. In this manuscript, we further investigated the association between callose synthase and microtubules through biochemical and ultrastructural analyses in the pollen tube model system, where callose is an essential component of the cell wall. Results by native 2-D electrophoresis, isolation of callose synthase complex and far-western blot confirmed that callose synthase is associated with tubulin and can therefore interface with cortical microtubules. In contrast, actin and sucrose synthase were not permanently associated with callose synthase. Immunogold labeling showed colocalization between the enzyme and microtubules, occasionally mediated by vesicles. Overall, the data indicate that pollen tube callose synthase exerts its activity in cooperation with the microtubular cytoskeleton
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Bayesian endogeneity bias modeling
We propose to model endogeneity bias using prior distributions of moment conditions. The estimator can be obtained both as a method-of-moments estimator and in a Ridge penalized regression framework. We show the estimator's relation to a Bayesian estimator
Physiological and biochemical responses to low non-freezing temperature of two Eucalyptus globulus clones differing in drought resistance
Abstract â We have compared the metabolic responses of leaves and roots of two Eucalyptus globulus L. clones CN5 and ST51 that differ in their
sensitivity to water deficits (ST51 is more drought sensitive), with regard to the effect of chilling (10/5 âŚC, day/night). We studied changes in growth,
osmotic potential and osmotically active compounds, soluble proteins, leaf pigments, and membrane lipid composition. Our data showed that both
clones have the ability to acclimatize to chilling temperatures. As a result of 10 days of acclimation, an increase of soluble sugars in leaves of treated
plants of both clones was observed that disappeared later on. Differences between clones were observed in the photosynthetic pigments and soluble
protein content which were more stable in CN5 under chilling. It also was apparent that CN5 presented a less negative predawn water potential (Ďpd)
and a higher leaf turgor than ST51 throughout the chilling treatment. In the case of the CN5, increased total lipids (TFA) and concomitant increase
of linolenic acid (C18:3) in leaves after acclimatization may be related to a better clone performance under chilling temperatures. Moreover, a higher
constitutive investment in roots in the case of CN5 as compared to ST51 may benefit new root regeneration under low temperatures favoring growth
after cold Mediterranean winter
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