752 research outputs found
Superscaling and Charge-changing Neutrino Cross Sections
The superscaling function extracted from inclusive electron scattering data
is used to predict high energy charge-changing neutrino cross sections in the
quasi-elastic and regions.Comment: 3 pages, 2 figures, to appear in the Proceedings of the 7th
International Workshop on Neutrino Factories and Superbeams, Laboratori
Nazionali di Frascati, Frascati (Rome), June 21 - 26, 200
Tooling materials compatible with carbon fibre composites in a microwave environment
Although metals are the most commonly used tooling materials to cure composites, they do not provide optimal results in a microwave environment. Following a selection process based on the properties of the materials, an alternative tooling material in carbon fibre reinforced plastic (CFRP) was successfully utilised to cure CFRP panels in laboratory and industrial microwaves. The conductive carbon fibres in the tool facilitated the fast heat transfer across the part. Other tooling materials including a glass fibre cyanate ester prepreg and tooling board were trialled, although the latter exhibited damage during cure. These advantages demonstrate that the CFRP tool is a compatible material that can be used when microwave curing composites
Extended Superscaling of Electron Scattering from Nuclei
An extended study of scaling of the first and second kinds for inclusive
electron scattering from nuclei is presented. Emphasis is placed on the
transverse response in the kinematic region lying above the quasielastic peak.
In particular, for the region in which electroproduction of resonances is
expected to be important, approximate scaling of the second kind is observed
and the modest breaking of it is shown probably to be due to the role played by
an inelastic version of the usual scaling variable.Comment: LaTeX, 36 pages including 5 color postscript figures and 4 postscript
figure
Scaling and isospin effects in quasielastic lepton-nucleus scattering in the Relativistic Mean Field Approach
The role of isospin in quasielastic electron scattering and charge-changing
neutrino reactions is investigated in the relativistic impulse approximation.
We analyze proton and neutron scaling functions making use of various
theoretical descriptions for the final-state interactions, focusing on the
effects introduced by the presence of strong scalar and vector terms in the
relativistic mean field approach. An explanation for the differences observed
in the scaling functions evaluated from and reactions is
provided by invoking the differences in isoscalar and isovector contributions.Comment: 10 pages, 5 figures, submitted to Phys. Lett.
Serum antioxidants as predictors of the adult respiratory distress syndrome in septic patients
Adult respiratory distress syndrome (ARDS) can develop as a complication of various disorders, including sepsis, but it has not been possible to identify which of the patients at risk will develop this serious disorder. We have investigated the ability of six markers, measured sequentially in blood, to predict development of ARDS in 26 patients with sepsis.
At the initial diagnosis of sepsis (6-24 h before the development of ARDS), serum manganese superoxide dismutase concentration and catalase activity were higher in the 6 patients who subsequently developed ARDS than in 20 patients who did not develop ARDS. These changes in antioxidant enzymes predicted the development of ARDS in septic patients with the same sensitivity, specificity, and efficiency as simultaneous assessments of serum lactate dehydrogenase activity and factor VIII concentration. By contrast, serum glutathione peroxidase activity and α1Pi-elastase complex concentration did not differ at the initial diagnosis of sepsis between patients who did and did not subsequently develop ARDS, and were not as effective in predicting the development of ARDS.
Measurement of manganese superoxide dismutase and catalase, in addition to the other markers, should facilitate identification of patients at highest risk of ARDS and allow prospective treatment
Relativistic effects in electromagnetic nuclear responses in the quasi-elastic delta region
A new non-relativistic expansion in terms of the nucleon's momentum inside
nuclear matter of the current for isobar electro-excitation from the nucleon is
performed. Being exact with respect to the transferred energy and momentum,
this yields new current operators which retain important aspects of relativity
not taken into account in the traditional non-relativistic reductions. The
transition current thus obtained differs from the leading order of the
traditional expansion by simple multiplicative factors. These depend on the
momentum and energy transfer and can be easily included together with
relativistic kinematics in non-relativistic, many-body models of isobar
electro-excitation in nuclei. The merits of the new current are tested by
comparing with the unexpanded electromagnetic nuclear responses in the isobar
peak computed in a relativistic Fermi gas framework. The sensitivity of the
relativistic responses to the isobar's magnetic, electric and Coulomb form
factors and the finite width of the isobar is analyzed.Comment: 26 pages plus 6 figure
Meson-exchange currents and quasielastic neutrino cross sections in the SuperScaling Approximation model
We evaluate the quasielastic double differential neutrino cross sections
obtained in a phenomenological model based on the superscaling behavior of
electron scattering data. We compare our results with the recent experimental
data for neutrinos of MiniBooNE and estimate the contribution of the vector
meson-exchange currents in the 2p-2h sector.Comment: 6 pages, 4 figure
Superscaling of Inclusive Electron Scattering from Nuclei
We investigate the degree to which the concept of superscaling, initially
developed within the framework of the relativistic Fermi gas model, applies to
inclusive electron scattering from nuclei. We find that data obtained from the
low energy loss side of the quasielastic peak exhibit the superscaling
property, i.e., the scaling functions f(\psi') are not only independent of
momentum transfer (the usual type of scaling: scaling of the first kind), but
coincide for A \geq 4 when plotted versus a dimensionless scaling variable
\psi' (scaling of the second kind). We use this behavior to study as yet poorly
understood properties of the inclusive response at large electron energy loss.Comment: 33 pages, 12 color EPS figures, LaTeX2e using BoxedEPSF macros; email
to [email protected]
Экспериментальные исследования двухфазных течений в разгонных трубках струйных мельниц
Розроблено й виготовлена осесиметричну модель ежектора струминного млина для дослідження двофазних течій у розгінній трубці струминного млина. Схема даної моделі за-снована на класичній схемі ежектора. Відмінність від класичної схеми складається в наяв-ності каналу підведення додаткового потоку. Канал підведення має кільцеву форму й забез-печує подачу рівномірно розподіленого захисного потоку в розгінний канал через щілинний отвір.
Проведено дослідження на осесимметричной моделі ежектора, що складалися із декі-лькох етапів, перший з яких полягав у вивченні характеру плину основного потоку в розгінній трубці млина, другий – у виявленні впливу додаткового потоку газу на основний потік, тре-тій – у виявленні впливу додаткового потоку газу, направленого до розгінної трубки під ку-том 30.
Аналіз досліджень показав, що додатковий потік газу виконує захисну функцію й запо-бігає впливу основного потоку на стінки розгінного каналу. Знайдені переваги додаткового потоку газу ,підведеного під кутом, меншим 90.
Виявлено необхідність досліджувати оптимальний кут підведення додаткового пото-ку газу.Разработана и изготовлена осесимметричная модель эжектора струйной мельницы для исследования двухфазных течений в разгонной трубке струйной мельницы. Схема данной модели основана на классической схеме эжектора. Отличие от классической схемы состо-ит в наличии канала подвода дополнительного потока. Канал подвода имеет кольцевую форму и обеспечивает подачу равномерно распределенного защитного потока в разгонный канал через щелевое отверстие.
Проведены исследования на осесимметричной модели эжектора, состоящие из не-скольких этапов, первый из которых заключался в изучении характера течения основного потока в разгонной трубке мельницы, второй – в выявлении влияния дополнительного пер-пендикулярного потока газа на основной поток, третий – в выявлении влияния дополни-тельного потока газа, направленного в разгонную трубку под углом 30.
Анализ исследований показал, что дополнительный поток газа выполняет защитную функцию и предотвращает влияние основного потока на стенки разгонного канала. Обна-ружены преимущества дополнительного потока газа, подведенного под углом, меньшим 90.
Выявлена необходимость исследовать оптимальный угол подвода дополнительного потока газа.Axisymmetric model of the jet mill ejector are designed and manufactured for studing two-phase flows in jet mill accelerating tube. The scheme of this model is based on the classical scheme of the ejector. Unlike the classical scheme is the inlet channel of an additional flow presence. A channel for supplying has an annular shape and provides the protective uniformly distributed flow in acceler-ating channel through the slotted inlet.
The researches on the axisymmetric ejector model are examined. They consisted of several stages, the first of which was to examine the main flow pattern in the mill accelerating tube, the sec-ond was to identify the additional gas flow impact on the main flow, the third – to identify the impact of the additional gas flow directed at an angle of 30 degrees into the accelerating tube.
Analyses of studies have shown that the additional gas flow has a protecting function and pre-vents the main flow effect on the accelerating channel walls. The benefits of the additional gas flow fed at an angle of less than 90 degrees are discovered.
The need of investigating the optimum angle of the additional gas flow feed is identified
Axion quasiparticles for axion dark matter detection
It has been suggested that certain antiferromagnetic topological insulators contain axion quasiparticles (AQs), and that such materials could be used to detect axion dark matter (DM). The AQ is a longitudinal antiferromagnetic spin fluctuation coupled to the electromagnetic Chern-Simons term, which, in the presence of an applied magnetic field, leads to mass mixing between the AQ and the electric field. The electromagnetic boundary conditions and transmission and reflection coefficients are computed. A model for including losses into this system is presented, and the resulting linewidth is computed. It is shown how transmission spectroscopy can be used to measure the resonant frequencies and damping coefficients of the material, and demonstrate conclusively the existence of the AQ. The dispersion relation and boundary conditions permit resonant conversion of axion DM into THz photons in a material volume that is independent of the resonant frequency, which is tuneable via an applied magnetic field. A parameter study for axion DM detection is performed, computing boost amplitudes and bandwidths using realistic material properties including loss. The proposal could allow for detection of axion DM in the mass range between 1 and 10 meV using current and near future technology
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