30,568 research outputs found
Government budget deficits in large open economies
Large and growing levels of public debt in the United States, United Kingdom, Japan and the Euro Area raise new interest in the cross-country effects of a large open economy's deficits. We consider a dynamic optimising model with costly tax collection and exogenously given public spending and initial debt. We ask whether the externalities associated with an individual country's deficits are positive or negative. We characterise the path of taxes in the Nash equilibrium where policy makers act nationalistically and compare this outcome to the global optimal outcome
Symmetry breakage in the development of one-armed gonads in nematodes
Whereas the hermaphrodite gonad of Caenorhabditis elegans has two symmetric arms (didelphy), the female/hermaphrodite gonad of many nematode species features a single anterior arm (monodelphy). We examined how gonadal cell lineages and intercellular signalling evolve to generate these diverse structures. In C. elegans, the two arms develop symmetrically from two somatic precursor cells, Z1 (anterior) and Z4 (posterior). Each first gives rise to one distal tip cell (which promotes arm growth and germ line proliferation), two ovary precursors and three uterine precursors in the center of the developing gonad. In monodelphic species, Z1 and Z4 have different fates. The first visible asymmetry between them is in the relative timing of their divisions, followed by asymmetric cell movements. The putative posterior distal tip cell is then eliminated in all but one species by programmed cell death. In some species the posterior ovary precursors form a small vestigial posterior arm, the post-vulval sac; in other species, they stay undivided, or die. In Cephalobus sp. PS1197, the specific fate of Z4 progeny is induced by Z1 (or its daughters). In the uterus in C. elegans, symmetric lateral signalling between Z1.ppp and Z4.aaa renders them equally likely to become the anchor cell, which links the uterus to the vulva. In the different monodelphic species, anchor cell specification is biased, or fully fixed, to a descendant of either Z1 or Z4. Replacement regulation upon anchor cell ablation is conserved in some species, but lost in others, leading to a mosaic-type development. Differentiation between Z1 and Z4 is thus manifested at this later stage in the breakage of symmetry of cell interactions in the ventral uterus
Alignment of the amino terminal amino acid sequence of human cytochrome c oxidase subunits I and II with the sequence of their putative mRNAs
Thirteen of the first fifteen amino acids from the NH2-terminus of the primary sequence of human cytochrome c oxidase subunit I and eleven of the first twelve amino acids of subunit II have been identified by microsequencing procedures. These sequences have been compared with the recently determined 5'-end proximal sequences of the HeLa cell mitochondrial mRNAS and unambiguously aligned with two of them. This alignment has allowed the identification of the putative mRNA for subunit I, and has shown that the initiator codon for this subunit is only three nucleotides away from the 5'-end of its mRNA; furthermore, the results have substantiated the idea that the translation of human cytochrome c oxidase subunit II starts directly at the 5'-end of its putative mRNA, as had been previously inferred on the basis of the sequence homology of human mitochondrial DNA with the primary sequence of the bovine subunit
Heavy-Tailed Features and Empirical Analysis of the Limit Order Book Volume Profiles in Futures Markets
This paper poses a few fundamental questions regarding the attributes of the
volume profile of a Limit Order Books stochastic structure by taking into
consideration aspects of intraday and interday statistical features, the impact
of different exchange features and the impact of market participants in
different asset sectors. This paper aims to address the following questions:
1. Is there statistical evidence that heavy-tailed sub-exponential volume
profiles occur at different levels of the Limit Order Book on the bid and ask
and if so does this happen on intra or interday time scales ?
2.In futures exchanges, are heavy tail features exchange (CBOT, CME, EUREX,
SGX and COMEX) or asset class (government bonds, equities and precious metals)
dependent and do they happen on ultra-high (<1sec) or mid-range (1sec -10min)
high frequency data?
3.Does the presence of stochastic heavy-tailed volume profile features evolve
in a manner that would inform or be indicative of market participant behaviors,
such as high frequency algorithmic trading, quote stuffing and price discovery
intra-daily?
4. Is there statistical evidence for a need to consider dynamic behavior of
the parameters of models for Limit Order Book volume profiles on an intra-daily
time scale ?
Progress on aspects of each question is obtained via statistically rigorous
results to verify the empirical findings for an unprecedentedly large set of
futures market LOB data. The data comprises several exchanges, several futures
asset classes and all trading days of 2010, using market depth (Type II) order
book data to 5 levels on the bid and ask
Integration of organic poultry in whole farm systems: manure nutrient budgets
This report was presented at the UK Organic Research 2002 Conference. The aim of this project was to examine how rotations incorporating organic poultry use the cycling of nutrients between soil, crops and birds. Poultry studies have measured nutrient values of manure in slow growing meat birds at about day 81 when fed typical broiler rations versus “Label Rouge” rations. Nutrient (N, P, K) balances were constructed to assess the viability of integrating poultry production within a theoretical organic rotation. The readilyplant- available nitrogen in manure from Ross 308 birds fed either presumed non-limiting rations or Label Rouge rations was within the range reported for intensive broilers. For ISA 657 birds, the manure readily-plant-available nitrogen was similar to the mean value reported for broilers, when fed presumed non limiting rations, but towards the lower range when fed Label Rouge rations. As breed growth and feed intakes differ it is suggested that to optimise the utilisation of nutrients, the nutrient content of table bird manures should be checked prior to land application. The nutrient budgets were similar for N and P regardless of the length of rotation or form of poultry production. On average, there was a surplus of 85 kg/ha N over all the scenarios. There tended to be a deficit of K in all scenarios (average: 10 kg/ha)
Is More Government Regulation Needed to Promote E-commerce?
E-commerce has experienced tremendous growth over the past few years. Nonetheless, senators, privacy watchdog groups, and the Federal Trade Commission have argued that e-commerce is being held back by consumer worries about online privacy and security. Some privacy advocates are calling for additional regulations, specifically new online privacy rules aimed at providing consumers with more information and customer choice. And Congress has tried to answer that call, most recently with a bill introduced by Senator Ernest Hollings. This essay examines the case for more government regulation and argues that the advocates have overstated their case. While some consumers, particularly older Americans and those new to the Internet, are clearly concerned about online privacy and security, these issues do not appear any more urgent for online shopping than offline shopping. Nor do these issues emerge as significant deterrents to e-commerce. Indeed, it is not even clear that any e-commerce has been deterred. Absent evidence of a significant market failure, the case for further government intervention is weak at best.Technology and Industry
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