2,127 research outputs found
Transportability, distributability and rehosting experience with a kernel operating system interface set
For the past two years, PRC has been transporting and installing a software engineering environment framework, the Automated Product control Environment (APCE), at a number of PRC and government sites on a variety of different hardware. The APCE was designed using a layered architecture which is based on a standardized set of interfaces to host system services. This interface set called the APCE Interface Set (AIS), was designed to support many of the same goals as the Common Ada Programming Support Environment (APSE) Interface Set (CAIS). The APCE was developed to provide support for the full software lifecycle. Specific requirements of the APCE design included: automation of labor intensive administrative and logistical tasks: freedom for project team members to use existing tools: maximum transportability for APCE programs, interoperability of APCE database data, and distributability of both processes and data: and maximum performance on a wide variety of operating systems. A brief description is given of the APCE and AIS, a comparison of the AIS and CAIS both in terms of functionality and of philosophy and approach and a presentation of PRC's experience in rehosting AIS and transporting APCE programs and project data. Conclusions are drawn from this experience with respect to both the CAIS efforts and Space Station plans
Concentration and Length Dependence of DNA Looping in Transcriptional Regulation
In many cases, transcriptional regulation involves the binding of transcription factors at sites on the DNA that are not immediately adjacent to the promoter of interest. This action at a distance is often mediated by the formation of DNA loops: Binding at two or more sites on the DNA results in the formation of a loop, which can bring the transcription factor into the immediate neighborhood of the relevant promoter. These processes are important in settings ranging from the historic bacterial examples (bacterial metabolism and the lytic-lysogeny decision in bacteriophage), to the modern concept of gene regulation to regulatory processes central to pattern formation during development of multicellular organisms. Though there have been a variety of insights into the combinatorial aspects of transcriptional control, the mechanism of DNA looping as an agent of combinatorial control in both prokaryotes and eukaryotes remains unclear. We use single-molecule techniques to dissect DNA looping in the lac operon. In particular, we measure the propensity for DNA looping by the Lac repressor as a function of the concentration of repressor protein and as a function of the distance between repressor binding sites. As with earlier single-molecule studies, we find (at least) two distinct looped states and demonstrate that the presence of these two states depends both upon the concentration of repressor protein and the distance between the two repressor binding sites. We find that loops form even at interoperator spacings considerably shorter than the DNA persistence length, without the intervention of any other proteins to prebend the DNA. The concentration measurements also permit us to use a simple statistical mechanical model of DNA loop formation to determine the free energy of DNA looping, or equivalently, the J-factor for looping
Reply to Comment on:"Nonmonotonic d_{x^2-y^2} Superconducting Order Parameter in Nd_{2-x}Ce_xCuO_4"
We confirm that all the results of scanning SQUID, tunneling, ARPES,
penetration depth and Raman experiments are consistent with a nonmonotonic
d_{x^2-y^2} superconducting order parameter proposed in Phys. Rev. Lett., 88,
107002 (2002).Comment: Reply to Comment by F. Venturini, R. Hackl, and U. Michelucci
cond-mat/020541
Crystal structure and high-field magnetism of La2CuO4
Neutron diffraction was used to determine the crystal structure and magnetic
ordering pattern of a La2CuO4 single crystal, with and without applied magnetic
field. A previously unreported, subtle monoclinic distortion of the crystal
structure away from the orthorhombic space group Bmab was detected. The
distortion is also present in lightly Sr-doped crystals. A refinement of the
crystal structure shows that the deviation from orthorhombic symmetry is
predominantly determined by displacements of the apical oxygen atoms. An
in-plane magnetic field is observed to drive a continuous reorientation of the
copper spins from the orthorhombic b-axis to the c-axis, directly confirming
predictions based on prior magnetoresistance and Raman scattering experiments.
A spin-flop transition induced by a c-axis oriented field previously reported
for non-stoichiometric La2CuO4 is also observed, but the transition field (11.5
T) is significantly larger than that in the previous work
Is there an integrative center in the vertebrate brain-stem? A robotic evaluation of a model of the reticular formation viewed as an action selection device
Neurobehavioral data from intact, decerebrate, and neonatal rats, suggests that the reticular formation provides
a brainstem substrate for action selection in the vertebrate central nervous system. In this article, Kilmer,
McCulloch and Blum’s (1969, 1997) landmark reticular formation model is described and re-evaluated, both in
simulation and, for the first time, as a mobile robot controller. Particular model configurations are found to
provide effective action selection mechanisms in a robot survival task using either simulated or physical robots.
The model’s competence is dependent on the organization of afferents from model sensory systems, and a genetic
algorithm search identified a class of afferent configurations which have long survival times. The results support
our proposal that the reticular formation evolved to provide effective arbitration between innate behaviors
and, with the forebrain basal ganglia, may constitute the integrative, ’centrencephalic’ core of vertebrate brain
architecture. Additionally, the results demonstrate that the Kilmer et al. model provides an alternative form of
robot controller to those usually considered in the adaptive behavior literature
Pi excitation of the t-J model
In this paper, we present analytical and numerical calculations of the pi
resonance in the t-J model. We show in detail how the pi resonance in the
particle-particle channel couples to and appears in the dynamical spin
correlation function in a superconducting state. The contribution of the pi
resonance to the spin excitation spectrum can be estimated from general
model-independent sum rules, and it agrees with our detailed calculations. The
results are in overall agreement with the exact diagonalization studies of the
t-J model. Earlier calculations predicted the correct doping dependence of the
neutron resonance peak in the YBCO superconductor, and in this paper detailed
energy and momentum dependence of the spin correlation function is presented.
The microscopic equations of motion obtained within current formalism agree
with that of the SO(5) nonlinear sigma model, where the pi resonance is
interpreted as a pseudo Goldstone mode of the spontaneous SO(5) symmetry
breaking.Comment: 33 pages, LATEX, 14 eps fig
ФАРМАКОДИНАМИЧЕСКАЯ ЭКВИВАЛЕНТНОСТЬ ПРИМЕНЕНИЯ3-МЕСЯЧНОЙ И 28-ДНЕВНОЙ ФОРМЫ ДЕКАПЕПТИЛА ДЕПО МЕДЛЕННОГО ВЫСВОБОЖДЕНИЯ У ПАЦИЕНТОВ С РАСПРОСТРАНЕННЫМ РАКОМ ПРЕДСТАТЕЛЬНОЙ ЖЕЛЕЗЫ
Objective: to evaluate the pharmacodynamic equivalence of 3-month and 28-day formulations of tryptoreline, a sustained-release luteininghormone (LH)-releasing hormone analogue.Subjects and methods. The patients who had a verified diagnosis of locally advanced or metastatic prostate cancer were randomized intogroups to have either one injection of a 3-month dosage form (n = 63) or 3 injections of a 28-day formulation at 28-day intervals (n = 68).The onset rate of drug-induced castration, which was defined as a percentage of the patients achieving a plasma testosterone level of ≤0.5ng/ml, was compared on day 84 (i.e. thrice every 28 days). The plasma profiles of testosterone, LH, and tryptoreline, as well as the changesin the plasma concentration of prostate-specific antigen (PCA) from the baseline values were estimated within 3 months (from the initiationof therapy to day 91).Results. In the 3-month and 28-day groups, the onset rate of drug-induced castration was 98 and 96%, respectively (at confidenceintervals (94.2% bilaterally) in [-8.1%; 9.6%]. The median time for drug-induced castration was 18.8 and 18.5 days, respective-ly (p = 0.86; log-rank test). The ratios of the mean peak plasma concentrations to AUC91 of the two formulations for testosteroneand LH were within 0.80; 1.25 equivalence interval. By day 91, the mean PSA level was decreased by 91.0 and 91.7%, respec-tively (p = 0.73).Conclusion. The use of the two formulations during 3 months is pharmacologically equal. Фармакодинамическая эквивалентность применения3-месячной и 28-дневной формы Декапептила депо медленного высвобождения у пациентов с распространенным раком предстательной железы
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