2,108 research outputs found
The 2009 analysis of information remaining on USB storage devices offered for sale on the second hand market
The use of the USB storage device, also known as the USB drive, a thumb drive, a keychain drive and a flash drive has, for the most part, replaced the floppy disk and to some extent the Compact Disk (CD), the DVD (Digital Video Disk or Digital Versatile Disk) and the external hard disk. Their robustness, size and weight make them easy to transport, but also to lose or misplace. They are inexpensive and are often given away as promotional items by organisations. Over the last few years there has been a dramatic increase in the storage capacity of these devices, going from a few tens of megabytes to a current capacity of around 64 gigabytes (equal to around 13 DVDs). The larger capacity and continued low cost has vastly increased the potential uses of the devices and also the volumes and types of data that they may contain
Double Exchange model for nanoscopic clusters
We solve the double exchange model on nanoscopic clusters exactly, and
specifically consider a six-site benzene-like nanocluster. This simple model is
an ideal testbed for studying magnetism in nanoclusters and for validating
approximations such as the dynamical mean field theory (DMFT). Non-local
correlations arise between neighboring localized spins due to the Hund's rule
coupling, favoring a short-range magnetic order of ferro- or antiferromagnetic
type. For a geometry with more neighboring sites or a sufficiently strong
hybridization between leads and the nanocluster, these non-local correlations
are less relevant, and DMFT can be applied reliably.Comment: 9 pages, 9 figures, 1 tabl
Shear viscosity of neutron matter from realistic nucleon-nucleon interactions
The calculation of transport properties of Fermi liquids, based on the
formalism developed by Abrikosov and Khalatnikov, requires the knowledge of the
probability of collisions between quasiparticles in the vicinity of the Fermi
surface. We have carried out a numerical study of the shear viscosity of pure
neutron matter, whose value plays a pivotal role in determining the stability
of rotating neutron stars, in which these processes are described using a
state-of-the-art nucleon-nucleon potential model. Within our approach medium
modifications of the scattering cross section are consistently taken into
account, through an effective interaction obtained from the matrix elements of
the bare interaction between correlated states. Inclusion of medium effects
lead to a large increase of the viscosity at densities larger than
fm^{-3}.Comment: 4 pages, 4 figures. Corrected typo
Set-up of a multi wavelength polar photometer for off-line absorption coefficient measurements on 1-h resolved aerosol samples
In this paper, a polar photometer (PP_UniMI) was set up to measure the aerosol absorption
coefficient (\u3c3ap) at four wavelengths (\u3bb) on 1-h resolved aerosol samples collected using a
streaker sampler. Due to the characteristics of such samples (small deposit area, low aerosol load,
and limited substrate thickness 12 10 \u3bcm), the main technical developments aimed at reaching
suitable limits of detection (LODs). To this aim, multiple scattering between the sample and a
suitable substrate were exploited to amplify the system sensitivity to absorbing particle load. In
the paper, the development and test of this innovative approach is presented.
LODs for \u3c3ap in the range 5.0\u201311.6 Mm 121 were reached, depending on the wavelength. Such
values were suitable for the analysis of 1-hour resolved samples collected at an urban background
site in Milan (Italy) during a test campaign of 1-week carried out in winter 2015. The
methodology was validated comparing \u3c3ap measurements performed by PP_UniMI at
\u3bb=635 nm on the streaker sample to the data obtained by a Multi-Angle Absorption
Photometer (MAAP) operated in parallel. Agreement within 10% was found. To check the
results obtained at other wavelengths, \uc5ngstr\uf6m Absorption Exponent (AAE) was calculated from
\u3c3ap measurements at 4-\u3bb. The AAE values resulted in the range of expectations for aerosol
emitted by fossil fuel combustion (0.8\u20131.2) and wood burning (0.9\u20133.5), which are the main
sources contributing to absorbing aerosol in urban areas in winter.
The analytical methodology can be extended to samples collected with high time resolution
using other high-time resolution samplers (e.g. drum rotating impactors).
This is \u2013 as far as we know \u2013 the first time that \u3c3ap measurements are performed on streaker
samples collected with 1-h resolution. Our results thus set PP_UniMI as an important tool for the
community performing high time resolved sampling to widen the characterisation of such
samples and to further develop source apportionment studies
Caloric stimulation of ampullar receptors: a new method to produce mechanically-evoked responses in frog semicircular canals
A microthermistor positioned close to the exposed posterior semicircular canal in isolated labyrinth preparations of the frog was used to stimulate the sensory organ. Our results indicated that, depending on the position of the heater, the induced endolymphatic convection currents may result in either excitatory or inhibitory cupular deflections and thus in a modulation of ampullar receptor resting activity. Other possible thermal-dependent mechanisms, such as a direct action of the stimulus on vestibular sensors or endolymphatic volume changes, had, in the present experimental conditions, a minor role. Caloric stimulation could therefore represent a novel method to stimulate the semicircular canals 'in situ'
- …