12,874 research outputs found
A precise determination of alpha_s from LEP thrust data using effective field theory
Starting from a factorization theorem in Soft-Collinear Effective Theory, the
thrust distribution in e+e- collisions is calculated including resummation of
the next-to-next-to-next-to leading logarithms. This is a significant
improvement over previous calculations which were only valid to next-to-leading
logarithmic order. The fixed-order expansion of the resummed result approaches
the exact fixed-order distribution towards the kinematic endpoint. This close
agreement provides a verification of both the effective field theory expression
and recently completed next-to-next-to-leading fixed order event shapes. The
resummed distribution is then matched to fixed order, resulting in a
distribution valid over a large range of thrust. A fit to ALEPH and OPAL data
from LEP 1 and LEP 2 produces alpha_s(m_Z)= 0.1172 +/- 0.0010 +/- 0.0008
+/-0.0012 +/- 0.0012, where the uncertainties are respectively statistical,
systematic, hadronic, and perturbative. This is one of the world's most precise
extractions of alpha_s to date.Comment: 37 pages, 12 figures; v2: hadronization discussion and appendices
expande
Precision direct photon and W-boson spectra at high p_T and comparison to LHC data
The differential p_T spectrum for vector boson production is computed at
next-to-leading fixed order and including the resummation of threshold
logarithms at next-to-next-to-leading logarithmic accuracy. A comparison is
made to ATLAS data on direct photon and W production at high transverse
momentum p_T, finding excellent agreement. The resummation is achieved by
factorizing contributions associated with different scales using Soft-Collinear
Effective Theory. Each part is then calculated perturbatively and the
individual contributions are combined using renormalization group methods. A
key advantage of the effective theory framework is that it indicates a set of
natural scale choices, in contrast to the fixed-order calculation. Resummation
of logarithms of ratios of these scales leads to better agreement with data and
reduced theoretical uncertainties.Comment: 24 pages, 10 figures; v2: journal version; v3: corrections in (20),
(37), (38
Generalized Colonel Blotto Game
Competitive resource allocation between adversarial decision makers arises in
a wide spectrum of real-world applications such as in communication systems,
cyber-physical systems security, as well as financial, political, and electoral
competition. As such, developing analytical tools to model and analyze
competitive resource allocation is crucial for devising optimal allocation
strategies and anticipating the potential outcomes of the competition. To this
end, the Colonel Blotto game is one of the most popular game-theoretic
frameworks for modeling and analyzing such competitive resource allocation
problems. However, in many real-world competitive situations, the Colonel
Blotto game does not admit solutions in deterministic strategies and, hence,
one must rely on analytically complex mixed-strategies with their associated
tractability, applicability, and practicality challenges. In this paper, a
generalization of the Colonel Blotto game which enables the derivation of
deterministic, practical, and implementable equilibrium strategies is proposed
while accounting for the heterogeneity of the battlefields. In addition, the
proposed generalized game enables accounting for the consumed resources in each
battlefield, a feature that is not considered in the classical Blotto game. For
the generalized game, the existence of a Nash equilibrium in pure-strategies is
shown. Then, closed-form analytical expressions of the equilibrium strategies,
are derived and the outcome of the game is characterized; based on the number
of resources of each player as well as the valuation of each battlefield. The
generated results provide invaluable insights on the outcome of the
competition. For example, the results show that, when both players are fully
rational, the more resourceful player can achieve a better total payoff at the
Nash equilibrium, a result that is not mimicked in the classical Blotto game.Comment: 8 pages, 5 figure
The Structure Inventory of the Nuclear Pore Complex
The nuclear pore complex (NPC) is the principal gateway for molecular exchange between nucleus and cytoplasm across the nuclear envelope. Due to its sheer size of estimated 50-112 MDa and its complex buildup from about 500-1000 individual proteins, it is a difficult object to study for structural biologists. Here, I review the extensive ensemble of high-resolution structures of the building blocks of the NPC. Concurrent with the increase in size and complexity, these latest, large structures and assemblies can now be used as the basis for hybrid approaches, primarily in combination with cryo-electron microscopic analysis, generating the first structure-based assembly models of the NPC. Going forward, the structures will be critically important for a detailed analysis of the NPC, including function, evolution, and assembly. Keywords: macromolecular complexes; nuclear pore complexNational Institutes of Health (U.S.) (Grant GM077537
A Study of the Relationship Between the Ideological Tendencies of United States Supreme Court Cases Affecting the Press, 1946-1974
Analysis of United States Supreme Court decision-making in cases affecting the press is important to communication law because many significant aspects of the court’s political behavior cannot be studied by reading the opinions of the court. The great volume of cases and range of issues simply preclude meaningful analysis except when subjected to the quantitative techniques of data processing and measurement. The hypotheses are: 1. Basic attitudes of Supreme Court justices contribute to their voting behavior. 2. Basic attitudes of Supreme Court justices in civil liberties cases. 3. Basic attitudes of Supreme Court justices toward press issues contribute to their voting behavior in press cases
No genetic evidence for involvement of Deltaretroviruses in adult patients with precursor and mature T-cell neoplasms
Background The Deltaretrovirus genus comprises viruses that infect humans (HTLV), various simian species (STLV) and cattle (BLV). HTLV-I is the main causative agent in adult T-cell leukemia in endemic areas and some of the simian T-cell lymphotropic viruses have been implicated in the induction of malignant lymphomas in their hosts. BLV causes enzootic bovine leukosis in infected cattle or sheep. During the past few years several new Deltaretrovirus isolates have been described in various primate species. Two new HTLV-like viruses in humans have recently been identified and provisionally termed HTLV-III and HTLV-IV. In order to identify a broad spectrum of Deltaretroviruses by a single PCR approach we have established a novel consensus PCR based on nucleotide sequence data obtained from 42 complete virus isolates (HTLV-I/-II, STLV-I/-II/-III, BLV). The primer sequences were based on highly interspecies-conserved virus genome regions. We used this PCR to detect Deltaretroviruses in samples from adult patients with a variety of rare T-cell neoplasms in Germany. Results: The sensitivity of the consensus PCR was at least between 10-2 and 10-3 with 100% specificity as demonstrated by serial dilutions of cell lines infected with either HTLV-I, HTLV-II or BLV. Fifty acute T-cell lymphoblastic leukemia (T-ALL) samples and 33 samples from patients with various rare mature T-cell neoplasms (T-PLL, Sezary syndrome and other T-NHL) were subsequently investigated. There were no cases with HTLV-I, HTLV-II or any other Deltaretroviruses. Conclusions: The results rule out a significant involvement of HTLV-I or HTLV-II in these disease entities and show that other related Deltaretroviruses are not likely to be involved. The newly established Deltaretrovirus PCR may be a useful tool for identifying new Deltaretroviruses
Structural and Functional Studies of the 252Â kDa Nucleoporin ELYS Reveal Distinct Roles for Its Three Tethered Domains
In metazoa, the nuclear envelope (NE), together with the embedded nuclear pore complexes (NPCs), breaks down and reassembles during cell division. It is suggested that ELYS, a nucleoporin, binds to chromatin in an initial step of postmitotic NPC assembly and subsequently recruits the essential Y-subcomplex, the major scaffolding unit of the NPC. Here, we show that ELYS contains three domains: an N-terminal β-propeller domain, a central α-helical domain, and a C-terminal disordered region. While the disordered region is responsible for the interactions with chromatin, the two preceding domains synergistically mediate tethering to the NPC. We present the crystal structure of the seven-bladed β-propeller domain at 1.9 Å resolution. Analysis of the β-propeller surface reveals the regions that are required for NPC anchorage. We discuss the possible roles of ELYS in the context of the NPC scaffold architecture.National Institutes of Health (U.S.) (Grant GM077537
Strategic Manipulability is Inescapable: Gibbard-Satterthwaite without Resoluteness
The Gibbard-Satterthwaite Theorem on the manipulability of collective-choice procedures treats only of resolute procedures. Few real or reasonable procedures are resolute. We prove a generalization of Gibbard-Satterthwaite that covers the nonresolute case. It opens harder questions than it answers about the prediction of behavior and outcomes and the design of institutions
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