188,148 research outputs found
FV Leiden pseudo-homozygotes have a more pronounced hypercoagulable state than FV Leiden homozygotes.
No full textJ Thromb Haemost. 2011 Apr;9(4):864-7. doi: 10.1111/j.1538-7836.2011.04205.x.
Factor V Leiden pseudo-homozygotes have a more pronounced hypercoagulable state
than factor V Leiden homozygotes.
Duckers C, Simioni P, Tormene D, Carraro S, Rosing J, Castoldi E.
PMID: 21251207 [PubMed - indexed for MEDLINE
The Mythos project: a distance learning experience in the field of lyric music
No full textSubject area: SHARING, videoconferencing, distance education, virtual communities ABSTRACT – The paper describes a distance learning experience in the field of lyric music operated by the CNIT consortium on a experimental terrestrial QoS-guaranteed IP telecommunication network in collaboration with the Arturo Toscanini foundation and Sinform, a consortium of institution that operates in the area of vocational training. Within the Mythos project, live classes for orchestra and chorus both at the individual and group level have taken place being the instructor (orchestra director) and the musicians (orchestra) in remote locations. The technical and artistic issues of this critical tele-teaching application have been identified and the relevant problems solved. 1
Efficient trellis search techniques for adaptive MLSE on fast Rayleigh fading channels
No full textWe analyze trellis search algorithms for joint sequence estimation and channel tracking, assuming rapidly varying frequency-selective Rayleigh fading. The Generalized Viterbi Algorithm (GVA) and the M-Algorithm (MA) are considered for approximately searching the maximum likelihood path in the trellis diagram and compared with the Viterbi Algorithm (VA). All algorithms perform channel tracking utilizing Per-Survivor Processing (PSP) techniques by associating a channel estimate
to each hypothetical trellis path, according to the Least Mean Square (LMS) or Recursive Least Square (RLS) algorithm.
To reproduce a typical mobile digital communication system,
a Time-Division Multiple Access (TDMA) data frame
is assumed, where each user transmits a block of information
symbols with known preamble and tail. For Doppler bands up to one hundredth the symbol frequency and a three path delay profile, the MA is shown to exhibit a slightly better performance than the GVA for an equal number of survivors, and outperform the VA
A Recursive Formulation for Quadratic Detection on Rayleigh Fading Channels
No full textWe address the problem of optimal detection of a random signal transmitted over a time-varying frequency-selective correlated Rayleigh fading channel. We present a general recursive solution which may be operated at full complexity to provide optimal detection or at reduced complexity, using per-survivor processing (PSP) techniques, to yield a suboptimal receiver
On the Use of Oversampling in Adaptive Receivers for Frequency-Selective Rayleigh Fading Channels
No full textIn this work, we investigate Maximum Likelihood Sequence Estimation (MLSE) of data sequences transmitted over time-varying frequency-selective Rayleigh fading channels and consider adaptive receivers which realize joint data estimation and channel tracking utilizing Per-Survivor Processing (PSP) techniques. In order to obtain a sufficient statistics for data detection, the received signal is oversampled with respect to the symbol rate. Accordingly, a time-discrete channel model with fractional spacing, with respect to the symbol interval, is assumed and an algorithm which performs fractionally-spaced
PSP-based channel tracking is analyzed. We show that receivers which employ this algorithm outperform traditional adaptive receivers based on one sample per symbol interval. Two samples per symbol interval are shown to be sufficient to attain the optimal performance for these receivers
On the Performance of the Quadratic Receiver for Rayleigh Fading Channels
No full textWe investigate maximum likelihood sequence estimation (MLSE) of data sequences transmitted over time-varying frequency-selective Rayleigh fading channels. We present the optimal receiver designed to exploit perfect channel state information (CSI) at the beginning of the data sequence and the optimal receiver which does not use this information. For any given data sequence length, a performance range for the optimal detection can be identified: this range is lower bounded by the optimal receiver with perfect CSI and upper bounded by that without CSI. Furthermore, this range narrows for increasing data sequence lengths. The performance of these optimal receivers is compared to that of some suboptimal receivers based on per-survivor processing (PSP) which perform joint sequence detection and channel tracking using the least mean square (LMS) algorithm. In terms of performance, these suboptimal receivers are shown to be intermediate between the optimal receivers with and without initial CSI. In addition, we show that the performance of both optimal receivers degrades significantly if they are provided with imperfect information about the signal-to-noise ratio or channel delay profile-information which is not necessary to the suboptimal PSP-based receivers
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