752 research outputs found
Attosecond pulse shaping around a Cooper minimum
High harmonic generation (HHG) is used to measure the spectral phase of the
recombination dipole matrix element (RDM) in argon over a broad frequency range
that includes the 3p Cooper minimum (CM). The measured RDM phase agrees well
with predictions based on the scattering phases and amplitudes of the
interfering s- and d-channel contributions to the complementary photoionization
process. The reconstructed attosecond bursts that underlie the HHG process show
that the derivative of the RDM spectral phase, the group delay, does not have a
straight-forward interpretation as an emission time, in contrast to the usual
attochirp group delay. Instead, the rapid RDM phase variation caused by the CM
reshapes the attosecond bursts.Comment: 5 pages, 5 figure
Principal component and multivariate factor analysis of detailed sheep milk fatty acid profile
Genomic selection of milk fatty acid composition in Sarda dairy sheep: Effect of different phenotypes and relationship matrices on heritability and breeding value accuracy
Attosecond Synchronization of High-Order Harmonics from Midinfrared Drivers
The group delay dispersion, also known as the attochirp, of high-order harmonics generated in gases has been identified as the main intrinsic limitation to the duration of Fourier-synthesized attosecond pulses. Theory implies that the attochirp, which is inversely proportional to the laser wavelength, can be decreased at longer wavelength. Here we report the first measurement of the wavelength dependence of the attochirp using an all-optical, in situ method [N. Dudovich et al., Nature Phys. 2, 781 (2006)]. We show that a 2 ÎĽm driving wavelength reduces the attochirp with respect to 0.8 ÎĽm at comparable intensities
Kearns-sayre syndrome with reduced plasma and cerebrospinal fluid folate
A young woman with Kearns-Sayre syndrome and progressive central nervous system deterioration over 15 years had decreased plasma and cerebrospinal fluid folate levels while receiving phenytoin for a seizure disorder. A muscle biopsy showed a “ragged red fiber” myopathy with reduced muscle carnitine and mitochondrial enzymes. Computed tomographic brain scans showed cerebral white matter hypodensities and bilateral calcification of the basal ganglia. The mechanism for the folate deficiency and altered ratio of plasma to cerebrospinal fluid folate is unknown, but the deficiency may be responsive to replacement therapy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50301/1/410130620_ftp.pd
Magnetic loss analysis in coaxial magnetic gears
This paper proposes a procedure for computing magnetic losses in coaxial magnetic gears. These magnetic structures are made of permanent magnets and ferromagnetic poles in relative motion transferring torque between two shafts in a contactless way. The loss computation in magnetic materials is crucial to define the system performance. The flux distribution inside the iron parts is computed by means of the finite element method and a model of iron losses taking into account the rotational nature of the flux loci is applied. The procedure highlights where the major loss sources are present and gives the opportunity to evaluate some corrective measures to reduce their effects. Particular attention is devoted to the 2D modeling in presence of permanent magnets segmentatio
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