10,212 research outputs found
Radial evolution of power spectra of interplanetary Alfvenic turbulence
The radial evolution of the power spectra of the MHD turbulence within the trailing edge of high speed streams in the solar wind was investigated with the magnetic field data of Helios 1 and 2 for heliocentric distance between 0.3 and 0.9 AU. In the analyzed frequency range (.00028 Hz to .0083 Hz) the computed spectra have, near the Earth, values of the spectral index close to that predicted for an incompressible hydromagnetic turbulence in a stationary state. Approaching the Sun the spectral slope remains unchanged for frequencies f or approximately .00 Hz, whereas at lower frequencies, a clear evolution toward a less steep fall off with frequency is found. The radial gradient of the power in Alfvenic fluctuations depends on frequency and it increases upon increasing frequency. For frequencies f or approximately .00 Hz, however, the radial gradient remains approximately the same. Possible theoretical implications of the observational features are discussed
On the polarization state of hydromagnetic fluctuations in the solar wind
From presently available observations it can be inferred that the Alfvenic turbulence measured in the solar wind, predominantly on trailing edges of high speed streams, is a mixture of modes with two different polarizations, namely, Alfvenic modes and modes which are the incompressible limit of slow magnetosonic waves. Using Helios 2 magnetic data and a variance analysis, parallel (to the mean field) and perpendicular components of the fluctuations are separated and the possible correlation between such components is studied. Correlations between eigenvalues of the variance matrix are also investigated and discussed
Magnetic dips in the solar wind
Using magnetic data from the HELIOS 1 fluxgate magnetometer, with a 0.2 sec resolution, the structures of several interplanetary discontinuities involving magnetic dips and rotations of the magnetic field vector were investigated. A minimum variance analysis illustrates the behavior of the magnetic field through the transition in the plane of its maximum variation. Using this analysis, quite different structures have been individuated and, in particular, narrow transitions resembling almost one dimensional reconnected neutral sheets. For the thinner cases (scale lengths of the magnetic rotation of the order or smaller than 1,000 km), results show the observed structures could be the nonlinear effect of a resistive tearing mode instability having developed on an originally one dimensional neutral sheet at the solar corona
VEGA SSMS HEX Module – Aggregation and Integration from EU to French Guiana
The paper describes the SSMS HEX Module Integration for the VEGA SSMS POC Flight. The integration, together with the aggregation of all the nano and picosatellites, took place in different European facilities between Europe and French Guiana. Among them, the SAB Aerospace facility in Brno played a fundamental role in the process. Indeed, all populated deployers have been integrated on the SSMS HEX Module in Brno. During the HEX Module integration, preliminary electrical checks for the satellites release have been performed. Finally, the finalization of the HEX Module has been performed in French Guiana at the Centre Spatial Guyanaisin Kourou (CSG) before the final integration between the SSMS Upper Part and SSMS Lower Part
Gaucher Disease and Myelofibrosis: A Combined Disease or a Misdiagnosis?
Background: Gaucher disease (GD) and primary myelofibrosis (PMF) share similar clinical and laboratory features, such as cytopenia, hepatosplenomegaly, and marrow fibrosis, often resulting in a misdiagnosis. Case Report: We report here the case of a young woman with hepatosplenomegaly, leukopenia, and thrombocytopenia. Based on bone marrow (BM) findings and on liver biopsy showing extramedullary hematopoiesis, an initial diagnosis of PMF was formulated. The patient refused stem cell transplantation from an HLA-identical sibling. Low-dose melphalan was given, without any improvement. Two years later, a BM evaluation showed Gaucher cells. Low glucocerebrosidase and high chitotriosidase levels were indicative for GD. Molecular analysis revealed N370S/complex I mutations. Enzyme replacement therapy with imiglucerase was commenced, resulting in clinical and hematological improvements. Due to an unexpected and persistent organomegaly, PMF combined with GD were suspected. JAK2V617F, JAK2 exon 12, MPL, calreticulin, and exon 9 mutations were negative, and BM examination showed no marrow fibrosis. PMF was excluded. Twenty years after starting treatment, the peripheral cell count and liver size were normal, whereas splenomegaly persisted. Conclusion: In order to avoid a misdiagnosis, a diagnostic algorithm for patients with hepatosplenomegaly combined with cytopenia is suggested
Innovative value-based price assessment in data-rich environments: Leveraging online review analytics through Data Envelopment Analysis to empower managers and entrepreneurs
This work introduces, develops, and empirically applies an innovative approach aimed at assessing selling prices based on the value perceived by the customers, as measured by electronic word-of-mouth (eWOM) in the guise of online reviews. To achieve this aim, it applies a constant return to scale Data Envelopment Analysis (DEA) approach where the price is the input, and the value attributes are the outputs measured through eWOM in the form of online reviews. We empirically apply the model to the hotel sector by considering both the prices and the service attributes (i.e., staff, location, cleanliness, comfort, facilities and free wi-fi) of 364 hotels based in two leading Italian tourism destinations: Milan and Rome. Our findings suggest that online review analytics can be suitably embedded into analytical models to assess prices. The index developed innovatively supports value-based pricing by means of online review analytics and it is easy-to-perform, and parsimonious as it is based on widely available information on the Internet
NMR and SR detection of unconventional spin dynamics in Er(trensal) and Dy(trensal) molecular magnets
Measurements of proton Nuclear Magnetic Resonance (1H NMR) spectra and
relaxation and of Muon Spin Relaxation (SR) have been performed as a
function of temperature and external magnetic field on two isostructural
lanthanide complexes, Er(trensal) and Dy(trensal) featuring
crystallographically imposed trigonal symmetry. Both the nuclear 1/T1 and muon
longitudinal relaxation rates, LRR, exhibit a peak for temperatures T
lower than 30K, associated to the slowing down of the spin dynamics, and the
width of the NMR absorption spectra starts to increase significantly at T ca.
50K, a temperature sizably higher than the one of the LRR peaks. The LRR peaks
have a field and temperature dependence different from those previously
reported for all Molecular Nanomagnets. They do not follow the
Bloembergen-Purcell-Pound scaling of the amplitude and position in temperature
and field and thus cannot be explained in terms of a single dominating
correlation time c determined by the spin slowing down at low
temperature. Further, for T lower than 50K the spectral width does not follow
the temperature behavior of the magnetic susceptibility chi. We suggest, using
simple qualitative considerations, that the observed behavior is due to a
combination of two different relaxation processes characterized by the
correlation times LT and HT, dominating for T lower than 30K and T
higher than 50K, respectively. Finally, the observed flattening of LRR for T
lower than 5K is suggested to have a quantum origin
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