To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Olfactory dysfunction is a possible side effect of chemo-radiotherapy performed in patients affected by nasopharyngeal carcinoma. Self-rating measurements and olfactory event-related potentials were used and compared in order to evaluate the impact of this treatment on the olfactory system.
Nine patients underwent subjective evaluation of olfactory function (using visual analogue scales for olfactory symptoms and quality of life, and a six-item Hyposmia Rating Scale), and a quantitative and objective measurement (olfactory event-related potentials).
Spearman's rank correlation analyses highlighted significant relationships between the clinical scales and olfactory event-related potentials. Inter-group analyses showed significant differences in the latency and in the amplitude of olfactory event-related potentials between patients and controls.
Taking into account the small sample size and the lack of pre-treatment assessment, olfactory event-related potentials seemed to allow a more objective diagnosis of unilateral and bilateral olfactory loss. Moreover, olfactory event-related potentials and subjective scales results were concordant.
Properties of entangled materials, made of fibers, depend on the number and the nature of contacts between fibers and fibers orientation. Nonsintered and sintered steel wools have been characterized by x-ray tomography to extract structural information such as fibers orientation and number of contacts before and during compression. Image analysis techniques were developed on tomography images and validated on virtual materials, generated and deformed by numerical simulation based on molecular dynamic equations. The structural parameters measured during the structural characterization were finally used to link the structure of the studied material with the measured mechanical properties. To do this link, an analytical model usually used for this kind of material was modified to describe the evolution of mechanical properties in compression.
Synchrotron x-ray microtomography is a characterization technique increasingly used to obtain 3D images of the interior of optically opaque materials with a spatial resolution in the micrometer range. As a nondestructive technique, it enables the monitoring of microstructural evolution during in situ experiments. In this article, examples from three different fields of metals research illustrate the contribution of x-ray tomography data to modeling: deformation of cellular materials, metal solidification, and fatigue crack growth in Al alloys. Conventionally, tomography probes the 3D distribution of the x-ray attenuation coefficient within a sample. However, this technique is also being extended to determine the local crystallographic orientation in the bulk of materials (diffraction contrast tomography), a key issue for the modeling of microstructure in metals.
The diffusion of B atoms in crystalline and amorphous Si has been experimentally investigated and modeled, evidencing the indirect mechanism of these mass transport phenomena. The migration of B occurs after interaction with self-interstitials in crystalline Si (c-Si) or with dangling bonds in amorphous Si (a-Si). In the first case, an accurate experimental design and a proper modeling allowed to determine the microscopic diffusion parameters as the B-defect interaction rate, the reaction paths leading to the diffusing species and its migration length. Moreover, by changing the Fermi level position, B atoms are shown to interact preferentially with neutral or doubly positively charged self-interstitials. As far as the amorphous case is concerned, B diffusion is revealed to have a marked transient character and to depend on the B concentration itself. In particular, boron atoms can move after the interaction with dangling bonds whose density is transiently increased after ion implantation or permanently enhanced by the presence of boron atoms themselves. Unexpectedly, B diffusivity in a-Si is seen to be orders of magnitude above than in c-Si and to depend on the thermal history, i.e. the relaxation status of the amorphous phase. These data are presented and their implications discussed.
We present spectroscopic and photometric data of a sample of Type II plateau Supernovae, covering a wide range of properties from the 56Ni rich, high luminosity events (e.g. SN 1992am) to the low-luminosity, 56Ni poor SNe (e.g. SN 1997D). We provide an observational framework to analyze correlations among observational data, physical parameters and progenitors characteristics of Type II supernovae.
We report on the serendipitous discovery of a new X-ray source, SAX J1802.7-2017, ~ 22' away from the bright X-ray source GX 9+l, during a BeppoSAX observation of the latter source on 2001 September 16-20.
The source was outside the FOV of the BeppoSAX/ LECS. We have verified its presence in both the MECS2 and MECS3 images, which probably excludes that this was a ghost image of a source outside the MECS FOV. Moreover, we can be sure that the source was within the PDS FOV. because the source X-ray pulsations were detected also in the PDS data (see below). We searched for known X-ray sources in a circular region of 30' centered at GX 9+1 in the SIMBAD data base. We found no known sources with a position compatible with that of the faint source; we therefore designate this serendipitous source as SAX J1802.7 2017.
We present preliminary results from a Chandra 30 ks observation of the atoll sourco 4U 1705 44. In particular we concentrate on the study of the iron Kα line, using the HEG spectrometer. The iron Kα line at ~ 6.6 keV is found to be intrinsically broad (FWHM ~ 1.7 keV); its width can be explained by reflection from a cold accretion disk extending down to ~ 17 km from the neutron star center or by Compton broadening in the hotter (~ 3 – 4 keV) corona.
We analyzed RXTE data from the burst of the year 2000 of the X-ray millisecond binary pulsar SAX J 1808.4-3658 with the intent of determining the new orbital parameters.
We used the observations of SAX J1808.4-3658 performed by the Rossi X-Ray Timing Explorer (RXTE) when the source was again detected in outburst during the period January-March 2000 (Wijnands et al. 2001). In particular we examined the data from the Proportional Counter Array (РСA) (Jahoda et al. 1996). We first applied barycentric correction to the data using the optical coordinates of the source (Roche et al. 98).
We present the first results of a monitoring campaign of the high-mass X-ray binary system 4U 1700-37/HD 153919, carried out with XMM-Newton.
We have observed the high-mass X-ray binary (HMXB) 4U 1700-37 with XMM-Newton at four orbital phases in February 2001. 4U 1700-37 is powered by the dense stellar wind of the O supergiant HD 153919. Numerous X-ray flares are observed with a typical duration, of the order of half an hour. We focus on three intervals in which the data are not affected by pile up: the eclipse, the eclipse egress and a low-flux part around orbital phase ϕ ~ 0.28.
The optical counterpart of the binary millisecond X-ray pulsar SAX J 1808.4-3658 during quiescence was detected at V = 21.5 mag, inconsistent with intrinsic emission from the fain companion star. We propose that the optical emission from this system during quiescence is due to the irradiation of the companion star and a remnant accretion disk by the rotational energy released by the fast spinning neutron star, switched on, as magneto-dipole rotator (radio pulsar). In this scenario the companion behaves as a bolometer, reprocessing in optical part of the power emitted by the pulsar. The reprocessed fraction depends only on known binary parameters. Thus the blackbody temperature of the companion can be predicted and compared with the observations. Our computations indicate that the observed optical magnitudes are fully consistent with this hypothesis. In this case the observed optical luminosity may be the first evidence that a radio pulsar is active in this system in quiescence.
The use of microtomography to study the structure and especially the deformation modes of cellular solids is reviewed in this article. First, the technique is described in detail. Examples illustrating the power of the coupling of in situ deformation with three-dimensional (3D) imaging, drawn from the recent literature and the authors' own work, are then given. The most detailed example is the study of the deformation modes of several samples made of different aluminum foams. Four kinds of closed-cell foams were investigated, corresponding to different routes available today for their manufacture. The initial macrostructure was quantified using the 3D images combined with 3D granulometry, allowing retrieval of pertinent information about the cell size and the wall and strut thicknesses. The global behavior exhibited by the foams during the in situ compression experiments was shown to vary from one brand of material to another. Some of these variations can be explained by differences in the known microstructure and the measured macrostructure of the samples.
This paper describes a method for producing model composites by the powder metallurgy route
in order to control the spatial distribution of the reinforcement in a metallic matrix.
The materials are fabricated by successive steps including mixing and extrusion. They are
then characterized in 3D by X-ray tomography.
Email your librarian or administrator to recommend adding this to your organisation's collection.