11,630 research outputs found
THE FEDERAL AGRICULTURE IMPROVEMENT AND REFORM ACT OF 1996: COMMODITY AND CONSERVATION PROGRAMS
The Federal Agriculture Improvement and Reform Act contains major revisions in farm commodity programs. This paper summarizes the major provision of legislation. Because many program implementation rules must be developed, program participants are advised to consult their local office of the USDA Farm Service Agency for final program provisions.Agricultural and Food Policy,
A PREVIEW OF THE 1996 FARM PROGRAM PROVISIONS
The U.S. House of Representatives and Senate have written farm bills that contain major revisions in farm commodity programs. Differences in these bills, House bill HR 2854 and Senate bill S 1541, must now be resolved by a Conference Committee, approved by a final vote of both houses of Congress, and signed by the President. Though differences in the bills do exist, the bills contain many similar provisions that appear likely to be included in the final version of the bill. This paper summarizes the major provisions of these bills and identifies areas where differences must be resolved by the Conference Committee.Agricultural and Food Policy,
The monoid of queue actions
We investigate the monoid of transformations that are induced by sequences of
writing to and reading from a queue storage. We describe this monoid by means
of a confluent and terminating semi-Thue system and study some of its basic
algebraic properties, e.g., conjugacy. Moreover, we show that while several
properties concerning its rational subsets are undecidable, their uniform
membership problem is NL-complete. Furthermore, we present an algebraic
characterization of this monoid's recognizable subsets. Finally, we prove that
it is not Thurston-automatic
In vitro evidence for senescent multinucleated melanocytes as a source for tumor-initiating cells
Oncogenic signaling in melanocytes results in oncogene-induced senescence (OIS), a stable cell-cycle arrest frequently characterized by a bi- or multinuclear phenotype that is considered as a barrier to cancer progression. However, the long-sustained conviction that senescence is a truly irreversible process has recently been challenged. Still, it is not known whether cells driven into OIS can progress to cancer and thereby pose a potential threat. Here, we show that prolonged expression of the melanoma oncogene N-RAS61K in pigment cells overcomes OIS by triggering the emergence of tumor-initiating mononucleated stem-like cells from senescent cells. This progeny is dedifferentiated, highly proliferative, anoikis-resistant and induces fast growing, metastatic tumors. Our data describe that differentiated cells, which are driven into senescence by an oncogene, use this senescence state as trigger for tumor transformation, giving rise to highly aggressive tumor-initiating cells. These observations provide the first experimental in vitro evidence for the evasion of OIS on the cellular level and ensuing transformation
A Persistent Simulation Environment for Autonomous Systems
The age of Autonomous Unmanned Aircraft Systems (AUAS) is creating new challenges for the accreditation and certification requiring new standards, policies and procedures that sanction whether a UAS is safe to fly. Establishing a basis for certification of autonomous systems via research into trust and trustworthiness is the focus of Autonomy Teaming and TRAjectories for Complex Trusted Operational Reliability (ATTRACTOR), a new NASA Convergent Aeronautics Solution (CAS) project. Simulation Environments to test and evaluate AUAS decision making may be a low-cost solution to help certify that various AUAS systems are trustworthy enough to be allowed to fly in current general and commercial aviation airspace. NASA is working to build a peer-to-peer persistent simulation (P3 Sim) environment. The P3 Sim will be a Massively Multiplayer Online (MMO) environment were AUAS avatars can interact with a complex dynamic environment and each other. The focus of the effort is to provide AUAS researchers a low-cost intuitive testing environment that will aid training for and assessment of decisions made by autonomous systems such as AUAS. This presentation focuses on the design approach and challenges faced in development of the P3 Sim Environment is support of investigating trustworthiness of autonomous systems
Microscopic dynamics of thin hard rods
Based on the collision rules for hard needles we derive a hydrodynamic
equation that determines the coupled translational and rotational dynamics of a
tagged thin rod in an ensemble of identical rods. Specifically, based on a
Pseudo-Liouville operator for binary collisions between rods, the Mori-Zwanzig
projection formalism is used to derive a continued fraction representation for
the correlation function of the tagged particle's density, specifying its
position and orientation. Truncation of the continued fraction gives rise to a
generalised Enskog equation, which can be compared to the phenomenological
Perrin equation for anisotropic diffusion. Only for sufficiently large density
do we observe anisotropic diffusion, as indicated by an anisotropic mean square
displacement, growing linearly with time. For lower densities, the Perrin
equation is shown to be an insufficient hydrodynamic description for hard
needles interacting via binary collisions. We compare our results to
simulations and find excellent quantitative agreement for low densities and
qualtitative agreement for higher densities.Comment: 21 pages, 6 figures, v2: clarifications and improved readabilit
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