535 research outputs found
The NuMI Neutrino Beam and Potential for an Off-Axis Experiment
The Neutrinos at the Main Injector (NuMI) facility at Fermilab is under
construction and due to begin operations in late 2004. NuMI will deliver an
intense beam of variable energy 2-20 GeV directed into the Earth at
58 mrad. Several aspects of the design are reviewed, and potential limitations
to the ultimate neutrino flux are described. In addition, potential
measurements of neutrino mixing properties are described.Comment: talk given at NuFact '02, Imperial College London, proceedings to
appear in J. Phys. G, revised to add a referenc
Определение основных характеристик пространственного маневра «переворот самолета» с ограничителем предельных режимов
Due to a steady extension of the flight envelope of modern agile combat aircraft, with the growing requirements for state tests, it is increasingly necessary to study the entire flight envelope and specifically, to determine the main performance data of individual maneuvers. Currently, state tests are based on a flight full-scale experiment, which is cost-ineffective in terms of cost, duration, and limit lines of the flight envelope. The accelerating trends to update state tests are semirealistic simulation and complex simulation modeling. The article presents the various techniques to determine main performance data of a three-dimensional maneuver split-S, which include the calculation method, semirealistic simulation, and simulation modeling. The calculation method is understood as calculation formulas expressed from the system of equations for motion of the aircraft mass center. Semirealistic simulation was carried out using a flight-simulation stand by operator pilots. Simulation modeling was conducted using a complex simulation model of an aircraft, consisting of a pilot’s control actions model based on fuzzy logic. The article provides the description, advantages and disadvantages, comparison of the results of each of the techniques. The calculation method, despite its efficiency, is the most inaccurate due to the complexity and inability to define the average flight parameters. Additionally, this method does not take into consideration such factors as the aircraft flight configuration, atmospheric disturbances, the pilot’s command profile, the logic of the permissible flight envelope limiter operation. The results of semirealistic simulation showed that this method is more accurate than the calculation one, but complex and time consuming in terms of the organization and execution of experiments. The analysis of the study illustrated that the most appropriate way to determine main performance data of split-S is simulation modeling on a complex simulation model of the aircraft, because the given method considerably saves financial and time resources used on state flight tests.В связи постоянным расширением эксплуатационного диапазона современных маневренных боевых самолетов, с ростом требований, предъявляемых к государственным испытаниям, все более необходимым является исследование всего эксплуатационного диапазона в целом и определение основных характеристик отдельно взятых маневров в частности. В настоящее время в основе государственных испытаний лежит летный натурный эксперимент, который невыгоден с точки зрения стоимости, длительности проведения и охвата всего эксплуатационного диапазона самолета. Одними из перспективных направлений совершенствования государственных испытаний являются полунатурное моделирование и комплексное имитационное моделирование. В статье представлены различные способы определения основных характеристик пространственного маневра «переворот», к которым относятся расчетный способ, полунатурное моделирование и имитационное моделирование. Под расчетным способом понимаются расчетные формулы, выраженные из системы уравнений движения центра масс летательного аппарата. Полунатурное моделирование проводилось на пилотажно-моделирующем стенде летчиками-операторами. Имитационное моделирование проводилось с использованием комплексной имитационной модели самолета, в состав которой входит модель управляющих действий летчика, основанная на нечеткой логике. В статье приведено описание, преимущества и недостатки, сравнение между собой результатов каждого из способов. Расчетный способ, несмотря на свою быстроту, является самым неточным способом из-за сложности и невозможности определения осредненных параметров полета. Также данный способ не учитывает такие факторы, как полетная конфигурация самолета, атмосферные возмущения, закон управления летчика, логику работы ограничителя предельных режимов. Результаты полунатурного моделирования показали, что данный способ является более точным, чем расчетный, но сложным и долгим в плане организации и выполнения экспериментов. Анализ исследования показал, что наиболее приемлемым способом определения основных характеристик переворота является имитационное моделирование на комплексной имитационной модели самолета, потому что данный способ в значительной степени позволяет экономить финансовые и временные ресурсы, затрачиваемые на государственные летные испытания
Gut microbiota and carcinogenesis in various human organs
Scientific research in recent years has revealed a significant role of the human microbiome in carcinogenesis. These data served as a rationale for the inclusion of polymorphic microbiomes in the key characteristics of carcinogenesis as an important mechanistic determinant of cancer, in addition to other fundamental biological processes manifested during multi-stage carcinogenesis. The microbiome of the gastrointestinal tract is most actively involved in the pathogenesis of malignant neoplasms of the digestive system due to changes in the quantitative and qualitative composition of the microbiota, and increase in the production of genotoxic bacterial metabolites as factors of carcinogenesis. This review also addresses the changes in the microbiome in lung cancer, associated mainly with the production of short-chain fatty aicids, and in breast and endometrial cancers with specific changes in the composition of the bacterial community towar)ds species involved in the metabolism of estrogen precursors. The probable mechanisms of microorganisms participation in the development of prostate cancer (the effect of lipopolysaccharides, antibiotics and deconjugated estrogen) are considered.
Data on the relationship between the composition and metabolic characteristics of the microbiome in various cancer sites open up perspectives for its use in the diagnosis, treatment and prevention of malignant neoplasms and justify the need for further research in this area
Forward Neutron Production at the Fermilab Main Injector
We have measured cross sections for forward neutron production from a variety
of targets using proton beams from the Fermilab Main Injector. Measurements
were performed for proton beam momenta of 58 GeV/c, 84 GeV/c, and 120 GeV/c.
The cross section dependence on the atomic weight (A) of the targets was found
to vary as where is for a beam momentum of
58 GeV/c and 0.540.05 for 120 GeV/c. The cross sections show reasonable
agreement with FLUKA and DPMJET Monte Carlos. Comparisons have also been made
with the LAQGSM Monte Carlo.Comment: Accepted for publication in Physical Review D. This version
incorporates small changes suggested by referee and small corrections in the
neutron production cross sections predicted by FLUK
Nonlinear Quantum Mechanics at the Planck Scale
I argue that the linearity of quantum mechanics is an emergent feature at the
Planck scale, along with the manifold structure of space-time. In this regime
the usual causality violation objections to nonlinearity do not apply, and
nonlinear effects can be of comparable magnitude to the linear ones and still
be highly suppressed at low energies. This can offer alternative approaches to
quantum gravity and to the evolution of the early universe.Comment: Talk given at the International Quantum Structures 2004 meeting, 16
pages LaTe
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