1,221 research outputs found
An overview of measurement and calibration methods for rotary control device based on parallel kinematic chains
A holomorphic representation of the Jacobi algebra
A representation of the Jacobi algebra by first order differential operators with polynomial
coefficients on the manifold is presented. The
Hilbert space of holomorphic functions on which the holomorphic first order
differential operators with polynomials coefficients act is constructed.Comment: 34 pages, corrected typos in accord with the printed version and the
Errata in Rev. Math. Phys. Vol. 24, No. 10 (2012) 1292001 (2 pages) DOI:
10.1142/S0129055X12920018, references update
Исследование кинематики формообразования зубчатых колес методом контурной обработки
Для процесу контурної обробки зубчатих коліс ексцентрично розташованою дисковою фрезою теоретично встановлено характер залежності форми одержаних профілів зубів від параметрів установки фрези і її геометричних розмірів. На базі зубофрезерного верстата мод. 5В312 з використовуванням фрезерної оправки із зміщеним центром осі обертання фрези експериментально доведено можливість використовування такої схеми для чорнової обробки евольвентніх зубчатих коліс.For process of gears’ contour machining by the eccentric placed disk-shaped milling cutter, dependence’s nature of obtained teeth’ form from parameters of milling cutter’s placement and its geometrical sizes was determined theoretically. By using a special tooling with eccentric axis of milling cutter rotation on the base of gear-hobbing machine 5В312, a possibility of using of this type of machining for involute gears’ roughing was proved experimentally.Для процесса контурной обработки зубчатых колес эксцентрически расположенной дисковой фрезой теоретически установлен характер зависимости формы полученных профилей зубов от параметров установки фрезы и ее геометрических размеров. На базе зубофрезерного станка мод. 5В312 с использованием фрезерной оправки со смещенным центром оси вращения фрезы экспериментально доказана возможность использования такой схемы для черновой обработки евольвентних зубчатых колес
Raman fingerprints of ultrasmall nanodiamonds produced from adamantane
The synthesis of ultrasmall (2-5 nm) nanodiamonds purely from adamantane at
pressure of 12 GPa is reported. Their structural features have been studied by
Raman spectroscopy. The unusual vibration band containing a number of
pronounced maxima at about 1147, 1245, 1344, and 1456 cm-1 was detected in
Raman spectra. The band is confidently identified with the bending vibrational
modes of CHx groups terminating the nanodiamonds surface. Excessively intense
mode at 1344 cm-1 is explained by its coupling with the 1328 cm-1 diamond
phonons. The Raman band found is proposed to be used for express recognition of
ultrasmall nanodiamonds produced from adamantane and other hydrocarbons with a
high hydrogen content. Moreover, polarized CH bonds on a diamond surface are
sensitive to environmental conditions. This opens up opportunities for using
the diamond produced from adamantane as ultrasmall nanosensors in biology,
chemistry, and medicineComment: 12 pages, 6 figure
Controlled trial of fish oil for regression of human coronary atherosclerosis
AbstractObjectives. This randomized clinical trial tested whether fish oil supplements can improve human coronary atherosclerosis.Background. Epidemiologic studies of populations whose intake of oily fish is high, as well as laboratory studies of the effects of the polyunsaturated fatty acids in fish oil, support the hypothesis that fish oil is antiatherogenic.Methods. Patients with angiographically documented coronary heart disease and normal plasma lipid levels were randomized to receive either fish oil capsules (n = 31), containing 6 g of n-3 fatty acids, or olive oil capsules (n = 28) for an average duration of 28 months. Coronary atherosclerosis on angiography was quantified by computer-assisted image analysis.Results. Mean (±SD) baseline characteristics were age 62 ± 7 years, plasma total cholesterol concentration 187 ± 31 mg/dl (4.83 ± 0.80 mmol/liter) and triglyceride levels 132 ± 70 mg/dl (1.51 ± 0.80 mmol/liter). Fish oil lowered triglyceride levels by 30% (p = 0.007) but had no significant effects on other plasma lipoprotein levels. At the end of the trial, eicosapentaenoic acid in adipose tissue samples was 0.91% in the fish oil group compared with 0.20% in the control group (p < 0.0001). At baseline, the minimal lumen diameter of coronary artery lesions (n = 305) was 1.64 ± 0.76 mm, and percent narrowing was 48 ± 14%. Mean minimal diameter of atherosclerotic coronary arteries decreased by 0.104 and 0.138 mm in the fish oil and control groups, respectively (p = 0.6 between groups), and percent stenosis increased by 2.4% and 2.6%, respectively (p = 0.8). Confidence intervals exclude improvement by fish oil treatment of >0.17 mm, or >2.6%.Conclusions. Fish oil treatment for 2 years does not promote major favorable changes in the diameter of atherosclerotic coronary arteries
Theoretical and experimental evidence of a site-selective Mott transition in Fe2O3 under pressure
We provide experimental and theoretical evidence for a novel type of
pressure-induced insulator-metal transition characterized by site-selective
delocalization of the electrons. M\"ossbauer spectroscopy, X-ray diffraction
and electrical transport measurements on FeO to 100 GPa, along with
dynamical mean-field theory (DFT+DMFT) calculations, reveal this site-selective
Mott transition between 50 and 68 GPa, such that the metallization can be
described by (^\rm{VI}Fe)O [ structure]
(^\rm{VIII}FeFe^\rm{M})O [ structure]
(^\rm{VI}Fe^\rm{M})O [
structure]. Within the crystal structure, characterized by two
distinct coordination sites (VI and VIII), we observe equal abundances of
ferric ions (Fe) and ions having delocalized electrons (Fe^\rm{M}),
and only at higher pressures is a fully metallic structure obtained, all
at room temperature. The transition is characterized by
delocalization/metallization of the electrons on half the Fe sites, with a
site-dependent collapse of local moments. Above 50 GPa, FeO is a
strongly correlated metal with reduced electron mobility (large band
renormalizations) of m*/m4 and 6 near the Fermi level. Upon
decompression, we observe a site-selective (metallic) to conventional Mott
insulator phase transition (^\rm{VIII}FeFe^\rm{M})O
(^\rm{VIII}FeFe)O within the same structure, indicating a decoupling of
the electronic and lattice degrees of freedom, characteristic of a true Mott
transition. Our results show that the interplay of electronic correlations and
lattice may result in rather complex behavior of the electronic structure and
magnetic state.Comment: 18 pages, 5 figure
Pamela: development of the RF system for a non-relativistic non-scaling FFAG
The PAMELA project(Particle Accelerator For MEdical
Applications) currently consists of the design of a particle
therapy facility. The project, which is in the design phase,
contains Non-Scaling FFAG, particle accelerator capable
of rapid beam acceleration, giving a pulse repetition rate of
1kHz, far beyond that of a conventional synchrotron. To
realise the repetition rate, a key component of the accelerator
is the rf accelerating system. The combination of a high
energy gain per turn and a high repetition rate is a significant
challenge. In this paper, options for the rf system of
the proton ring and the status of development are presented
Urine disinfection and in situ pathogen killing using a Microbial Fuel Cell cascade system
© 2017 Ieropoulos et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Microbial Fuel Cells (MFCs) are emerging as an effective means of treating different types of waste including urine and wastewater. However, the fate of pathogens in an MFC-based system remains unknown, and in this study we investigated the effect of introducing the enteric pathogen Salmonella enterica serovar enteritidis in an MFC cascade system. The MFCs continuously fed with urine showed high disinfecting potential. As part of two independent trials, during which the bioluminescent S. enteritidis strain was introduced into the MFC cascade, the number of viable counts and the level of bioluminescence were reduced by up to 4.43-0.04 and 4.21-0.01 log-fold, respectively. The killing efficacy observed for the MFCs operating under closed-circuit conditions, were higher by 1.69 and 1.72 log-fold reduction than for the open circuit MFCs, in both independent trials. The results indicated that the bactericidal properties of a well performing anode were dependent on power performance and the oxidation-reduction potential recorded for the MFCs. This is the first time that the fate of pathogenic bacteria has been investigated in continuously operating MFC systems
Anomalous magnetic response of the spin-one-half Falicov-Kimball model
The infinite-dimensional spin one-half Falicov-Kimball model in an external
magnetic field is solved exactly. We calculate the magnetic susceptibility in
zero field, and the magnetization as a function of the field strength. The
model shows an anomalous magnetic response from thermally excited local moments
that disappear as the temperature is lowered. We describe possible real
materials that may exhibit this kind of anomalous behavior.Comment: 17 pages, 6 encapsulated postscript figures (included), submitted to
Phys. Rev.
Donor-acceptor recombination emission in hydrogen-terminated nanodiamond: Novel single-photon source for room-temperature quantum photonics
In fluorescence spectra of nanodiamonds (NDs) synthesized at high pressure
from adamantane and other organic compounds, very narrow (~1 nm) lines of
unknown origin are observed in a wide spectroscopic range from ~500 to 800 nm.
Here, we propose and experimentally substantiate the hypothesis that these
mysterious lines arise from radiative recombination of donor-acceptor pairs
(DAPs). To confirm our hypothesis, we study the fluorescence spectra of undoped
and nitrogen-doped NDs of different sizes, before and after thermal oxidation
of their surface. The results obtained with a high degree of confidence allowed
us to conclude that the DAPs are formed through the interaction of donor-like
substitutional nitrogen present in the diamond lattice, and a 2D layer of
acceptors resulting from the transfer doping effect on the surface of
hydrogen-terminated NDs. A specific behavior of the DAP-induced lines was
discovered in the temperature range of 100-10 K: their energy increases and
most lines are split into 2 or more components with decreasing temperature. It
is shown that the majority of the studied DAP emitters are sources of single
photons, with an emission rate of up to >1 million counts/s at room
temperature, which significantly surpasses that of nitrogen-vacancy and
silicon-vacancy centers under the same detection conditions. Despite an
observed temporal instability in the emission, the DAP emitters of H-terminated
NDs represent a powerful room-temperature single-photon source for quantum
optical technologies
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