202 research outputs found
Multistage Switching Architectures for Software Routers
Software routers based on personal computer (PC) architectures are becoming an important alternative to proprietary and expensive network devices. However, software routers suffer from many limitations of the PC architecture, including, among others, limited bus and central processing unit (CPU) bandwidth, high memory access latency, limited scalability in terms of number of network interface cards, and lack of resilience mechanisms. Multistage PC-based architectures can be an interesting alternative since they permit us to i) increase the performance of single software routers, ii) scale router size, iii) distribute packet manipulation and control functionality, iv) recover from single-component failures, and v) incrementally upgrade router performance. We propose a specific multistage architecture, exploiting PC-based routers as switching elements, to build a high-speed, largesize,scalable, and reliable software router. A small-scale prototype of the multistage router is currently up and running in our labs, and performance evaluation is under wa
Actigraphic sleep detection: an artificial intelligence approach
Objective: Polysomnography is the gold standard for sleep monitoring, despite its many drawbacks: it is complex, costly and rather
invasive. Medical-grade actigraphy represents an acceptably accurate alternative for the estimation of sleep patterns in normal, healthy
adult populations and in patients suspected of certain sleep disorders. An increasing number of consumer-grade accelerometric
devices populate the âquantified-selfâ market but the lack of validation significantly limits their reliability. Our aim was to prototype and
validate a platform-free artificial neural network (ANN) based algorithm applied to a high performance, open source device (Axivity
AX3), to achieve accurate actigraphic sleep detection. Methods: 14 healthy subjects (29.35 14.40 yrs, 7 females) were
equipped for 13.3 2.58 h with portable polysomnography (pPSG), while wearing the Axivity AX3. The AX3 was set to record 3D
accelerations at 100 Hz, with a dynamic range of 8 g coded at 10 bit. For the automatic actigraphy-based sleep detection, a 4 layer
artificial neural network has been trained, validated and tested against the pPSG-based expert visual sleep-wake scoring.
Results: When compared to the pPSG gold standard scoring, the ANN-based algorithm reached high concordance (85.3 0.06%),
specificity (87.3 0.04%) and sensitivity (84.6 0.1%) in the detection of sleep over 30-sec epochs. Moreover there were no
statistical differences between pPSG and actigraphy-based Total Sleep Time and Sleep Efficiency measurements (Wilcoxon test).
Conclusions: The high concordance rate between ANN-actigraphy scoring and the standard visual pPSG one suggests that this
approach could represent a viable method for collecting objective sleep-wake data using a high performance, open source actigraph
Do we really need hazard prevention at the expense of safeguarding death dignity in covid-19?
To date, little is known regarding the transmission risks of SARS-CoV-2 infection for subjects involved in handling, transporting, and examining deceased persons with known or suspected COVID-19 positivity at the time of death. This experimental study aims to define if and/or how long SARS-CoV-2 persists with replication capacity in the tissues of individuals who died with/from COVID-19, thereby generating infectious hazards. Sixteen patients who died with/from COVID-19 who underwent autopsy between April 2020 and April 2021 were included in this study. Based on PMI, all samples were subdivided into two groups: âshort PMIâ group (eight subjects who were autopsied between 12 to 72 h after death); âlong PMIâ (eight subjects who were autopsied between 24 to 78 days after death). All patients tested positive for RT-PCR at nasopharyngeal swab both before death and on samples collected during post-mortem investigation. Moreover, a lung specimen was collected and frozen at â80⊠C in order to perform viral culture. The result was defined based on the cytopathic effect (subjective reading) combined with the positivity of the RT-PCR test (objective reading) in the supernatant. Only in one sample (PMI 12 h), virus vitality was demonstrated. This study, supported by a literature review, suggests that the risk of cadaveric infection in cases of a person who died from/with COVID-19 is extremely low in the first hours after death, becoming null after 12 h after death, confirming the World Health Organization (WHO) assumed in March 2020 and suggesting that the corpse of a subject who died from/with COVID-19 should be generally considered not infectious
Finite Density QCD: a New Approach
We introduce a new approach to analyze the phase diagram of QCD at finite
chemical potential and temperature, test it in the Gross-Neveu model at finite
baryon density, and apply it to the study of the chemical potential-temperature
phase diagram of QCD with four degenerate flavors of Kogut-Susskind type.Comment: 21 pages, 9 figures. Some comments and references adde
Theta dependence of CP^9 model
We apply to the model two recently proposed numerical techniques for
simulation of systems with a theta term. The algorithms, successfully tested in
the strong coupling limit, are applied to the weak coupling region. The results
agree and errors have been evaluated and are at % level. The results scale well
with the renormalization group equation and show that, for in presence
of a theta term, CP symmetry is spontaneously broken at in the
continuum limit.Comment: 4 pages, 4 figure
The Schwinger Model on the lattice in the Microcanonical Fermionic Average approach
The Microcanonical Fermionic Average method has been used so far in the
context of lattice models with phase transitions at finite coupling. To test
its applicability to Asymptotically Free theories, we have implemented it in
QED, \it i.e.\rm the Schwinger Model. We exploit the possibility, intrinsic
to this method, of studying the whole plane at negligible computer
cost, to follow constant physics trajectories and measure the limit
of the chiral condensate. We recover the continuum result within 3 decimal
places.Comment: TeX file, 7 pages + 3 figures in Postscrip
Diquark condensation at strong coupling
The possibility of diquark condensation at sufficiently large baryon chemical
potential and zero temperature is analyzed in QCD at strong coupling. In
agreement with other strong coupling analysis, it is found that a first order
phase transition separates a low density phase with chiral symmetry
spontaneously broken from a high density phase where chiral symmetry is
restored. In none of the phases diquark condensation takes place as an
equilibrium state, but, for any value of the chemical potential, there is a
metastable state characterized by a non-vanishing diquark condensate. The
energy difference between this metastable state and the equilibrium state
decreases with the chemical potential and is minimum in the high density phase.
The results indicate that there is attraction in the quark-quark sector also at
strong coupling, and that the attraction is more effective at high baryon
density, but for infinite coupling it is not enough to produce diquark
condensation. It is argued that the absence of diquark condensation is not a
peculiarity of the strong coupling limit, but persists at sufficiently large
finite couplings.Comment: 10 pages, 2 figures. An important discussion concerning the extension
of the results to finite couplings adde
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