4,700 research outputs found
Models of Russia's Macroeconomic Policy at the Turn of the 21st Century
At present the modelling of macroeconomic processes appears to hold theoretical as well as applied interest. Hence, in the present article this method is used with regard to the Russian economy, presenting its actual economic practice in the last decade of the 20th and at the beginning of the 21st century. The author describes three macroeconomic models, taking into consideration the fact that the country is being profoundly influenced by the global financial crisis. The discussed models are: transition economy model, economic growth model and crisis-management model.Autor analizuje w artykule trzy modele makroekonomiczne polityki gospodarczej: model gospodarki transformujÄ
cej siÄ, model wzrostu gospodarczego i model zarzÄ
dzania kryzysem
Analyzing the Gender Gap on an Entrance Exam for Mathematically Talented Students
We investigate the qualifying entrance exam for the University of Minnesota Talented Youth Mathematics Program (UMTYMP), a five-year accelerated program covering high school- and undergraduate-level mathematics. The exam is used to assess the computational, numerical reasoning, and geometric skills of hundreds of fifth-, sixth-, and seventh-grade students annually. It has accurately identified qualified students in past years, but female participants consistently have had lower overall scores. Based on our belief that they are equally well qualified, in 2011 we began an extensive investigation into the structure and content of the exam to determine the possible sources for these differences. After gathering and analyzing data, we made relatively modest changes in 2012 which essentially eliminated the gender bias on one version of the entrance exam, increasing the percentage of females who qualified. The other unmodified versions in 2012 exhibited the typical gender difference from previous years. We continue to analyze the possible reasons for the gender differences while monitoring the overall student performance upon entering the Program
Cytochrome P450 oxidoreductase participates in nitric oxide consumption by rat brain
In low nanomolar concentrations, NO (nitric oxide) functions as a transmitter in brain and other tissues, whereas near-micromolar NO concentrations are associated with toxicity and cell death. Control of the NO concentration, therefore, is critical for proper brain function, but, although its synthesis pathway is well-characterized, the major route of breakdown of NO in brain is unclear. Previous observations indicate that brain cells actively consume NO at a high rate. The mechanism of this consumption was pursued in the present study. NO consumption by a preparation of central glial cells was abolished by cell lysis and recovered by addition of NADPH. NADPH-dependent consumption of NO localized to cell membranes and was inhibited by proteinase K, indicating the involvement of a membrane-bound protein. Purification of this activity yielded CYPOR (cytochrome P450 oxidoreductase). Antibodies against CYPOR inhibited NO consumption by brain membranes and the amount of CYPOR in several cell types correlated with their rate of NO consumption. NO was also consumed by purified CYPOR but this activity was found to depend on the presence of the vitamin E analogue Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid), included in the buffer as a precaution against inadvertent NO consumption by lipid peroxidation. In contrast, NO consumption by brain membranes was independent of Trolox. Hence, it appears that, during the purification process, CYPOR becomes separated from a partner needed for NO consumption. Cytochrome P450 inhibitors inhibited NO consumption by brain membranes, making these proteins likely candidates
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Trafficking and processing of bacterial proteins by mammalian cells: Insights from chondroitinase ABC.
Background: There is very little reported in the literature about the relationship between modifications of bacterial proteins and their secretion by mammalian cells that synthesize them. We previously reported that the secretion of the bacterial enzyme Chondroitinase ABC by mammalian cells requires the strategic removal of at least three N-glycosylation sites. The aim of this study was to determine if it is possible to enhance the efficacy of the enzyme as a treatment for spinal cord injury by increasing the quantity of enzyme secreted or by altering its cellular location.
Methodology/principal findings: To determine if the efficiency of enzyme secretion could be further increased, cells were transfected with constructs encoding the gene for chondroitinase ABC modified for expression by mammalian cells; these contained additional modifications of strategic N-glycosylation sites or alternative signal sequences to direct secretion of the enzyme from the cells. We show that while removal of certain specific N-glycosylation sites enhances enzyme secretion, N-glycosylation of at least two other sites, N-856 and N-773, is essential for both production and secretion of active enzyme. Furthermore, we find that the signal sequence directing secretion also influences the quantity of enzyme secreted, and that this varies widely amongst the cell types tested. Last, we find that replacing the 3âUTR on the cDNA encoding Chondroitinase ABC with that of ÎČ-actin is sufficient to target the enzyme to the neuronal growth cone when transfected into neurons. This also enhances neurite outgrowth on an inhibitory substrate.
Conclusion/significance: Some intracellular trafficking pathways are adversely affected by cryptic signals present in the bacterial gene sequence, whilst unexpectedly others are required for efficient secretion of the enzyme. Furthermore, targeting chondroitinase to the neuronal growth cone promotes its ability to increase neurite outgrowth on an inhibitory substrate. These findings are timely in view of the renewed prospects for gene therapy, and of direct relevance to strategies aimed at expressing foreign proteins in mammalian cells, in particular bacterial proteins
Risk, Uncertainty, and the Perceived Threat of Terrorist Attacks: Evidence of Flight-to-Quality
© 2013 World Scientific Publishing Company and Midwest Finance Association. Information provided by the US Department of Homeland Security regarding potential terrorist attacks significantly affects US Treasury securities markets. When the government announces heightened terror alert levels, investors\u27 perceptions of risk increase and investors purchase 1-month and 1-year Treasury bills and 3-year, 5-year, 7-year, and 10-year US Treasuries in a flight-to-quality episode. Partial anticipation of increased threat level announcements is stronger than the anticipation of announcements regarding the federal funds rate during the 10 days prior to an announcement
Structurally dynamic spin market networks
The agent-based model of stock price dynamics on a directed evolving complex
network is suggested and studied by direct simulation. The stationary regime is
maintained as a result of the balance between the extremal dynamics, adaptivity
of strategic variables and reconnection rules. The inherent structure of node
agent "brain" is modeled by a recursive neural network with local and global
inputs and feedback connections. For specific parametric combination the
complex network displays small-world phenomenon combined with scale-free
behavior. The identification of a local leader (network hub, agent whose
strategies are frequently adapted by its neighbors) is carried out by repeated
random walk process through network. The simulations show empirically relevant
dynamics of price returns and volatility clustering. The additional emerging
aspects of stylized market statistics are Zipfian distributions of fitness.Comment: 13 pages, 5 figures, accepted in IJMPC, references added, minor
changes in model, new results and modified figure
Extensive molecular differences between anterior- and posterior-half-sclerotomes underlie somite polarity and spinal nerve segmentation
The mechanism of the Einstellung (set) effect: A pervasive source of cognitive bias
Copyright @ The Authors 2010The eye movements of expert players trying to solve a chess problem show that the first idea that comes to mind directs attention towards sources of information consistent with itself and away from inconsistent information. This bias continues unconsciously even when the player believes he is looking for alternatives. The result is that alternatives to the first idea are ignored. This mechanism for biasing attention ensures a speedy response in familiar situations but it can lead to errors when the first thought that comes to mind is not appropriate. We propose that this mechanism is the source of many cognitive biases from phenomena in problem solving and reasoning, to perceptual errors and failures in memory
Designed to fail : a biopolitics of British Citizenship.
Tracing a route through the recent 'ugly history' of British citizenship, this article advances two central claims. Firstly, British citizenship has been designed to fail specific groups and populations. Failure, it argues, is a design principle of British citizenship, in the most active and violent sense of the verb to design: to mark out, to indicate, to designate. Secondly, British citizenship is a biopolitics - a field of techniques and practices (legal, social, moral) through which populations are controlled and fashioned. This article begins with the 1981 Nationality Act and the violent conflicts between the police and black communities in Brixton that accompanied the passage of the Act through the British parliament. Employing Michel Foucault's concept of state racism, it argues that the 1981 Nationality Act marked a pivotal moment in the design of British citizenship and has operated as the template for a glut of subsequent nationality legislation that has shaped who can achieve citizenship. The central argument is that the existence of populations of failed citizens within Britain is not an accident of flawed design, but is foundational to British citizenship. For many 'national minorities' the lived realities of biopolitical citizenship stand in stark contradistinction to contemporary governmental accounts of citizenship that stress community cohesion, political participation, social responsibility, rights and pride in shared national belonging
Quantum cat maps with spin 1/2
We derive a semiclassical trace formula for quantized chaotic transformations
of the torus coupled to a two-spinor precessing in a magnetic field. The trace
formula is applied to semiclassical correlation densities of the quantum map,
which, according to the conjecture of Bohigas, Giannoni and Schmit, are
expected to converge to those of the circular symplectic ensemble (CSE) of
random matrices. In particular, we show that the diagonal approximation of the
spectral form factor for small arguments agrees with the CSE prediction. The
results are confirmed by numerical investigations.Comment: 26 pages, 3 figure
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