The effect of varying stimulus rate and duration on brain activity during reading

The effect of the presentation rate and exposure duration of visually presented words on brain activity was investigated using positron emission tomography. Subjects either read aloud or silently mouthed the names of words. In regions associated with early visual analysis, activity increased with both rate and duration; in regions associated with response generation, activity increased with increasing rate but was unaffected by duration; and in regions associated with word recognition, activity decreased with increasing duration. The variable responses of different brain regions illustrate the functional segregation of these regions. Of particular interest was the dissociation between activity in the posterior fusiform gyri and that in the medial lingual gyrus--in the former, activity increased with rate and duration but the latter was unaffected by either variable. This finding suggests that word processing in the lingual gyrus during reading is distinct from that in the posterior fusiform gyri. A further observation was that during reading aloud, when subjects can hear the sound of their own voice, the response in the primary auditory cortices increased with stimulus rate, demonstrating that subjects process the sound of their own voice in a qualitatively similar way to words spoken by another.     

Embedded access points for trusted data and resources access in HPC systems

Biometric authentication systems represent a valid alternative to the conventional username–password based approach for user authentication. However, authentication systems composed of a biometric reader, a smartcard reader, and a networked workstation which perform user authentication via software algorithms have been found to be vulnerable in two areas: firstly in their communication channels between readers and workstation (communication attacks) and secondly through their processing algorithms and/or matching results overriding (replay attacks, confidentiality and integrity threats related to the stored information of the networked workstation). In this paper, a full hardware access point for HPC environments is proposed. The access point is composed of a fingerprint scanner, a smartcard reader, and a hardware core for fingerprint processing and matching. The hardware processing core can be described as a Handel-C algorithmic-like hardware programming language and prototyped via a Field Programmable Gate Array (FPGA) based board. The known indexes False Acceptance Rate (FAR) and False Rejection Rate (FRR) have been used to test the prototype authentication accuracy. Experimental trials conducted on several fingerprint DBs show that the hardware prototype achieves a working point with FAR=1.07% and FRR=8.33% on a proprietary DB which was acquired via a capacitive scanner, a working point with FAR=0.66% and FRR=6.13% on a proprietary DB which was acquired via an optical scanner, and a working point with FAR=1.52% and FRR=9.64% on the official FVC2002_DB2B database. In the best case scenario (depending on fingerprint image size), the execution time of the proposed recognizer is 183.32 ms.     

20 dBm linearly polarised tunable single-frequency diode-pumpedEr:Yb laser at 1535 nm using anisotropic absorptive intracavity etalon

A linearly polarised single-frequency diode-pumped Er:Yb bulk laser with output power in excess of 100 mW has been demonstrated. The use of an anisotropic absorptive intracavity etalon to achieve both single-frequency operation and linearly polarised output is investigated. Output power and tuning characteristics as well as relative-intensity noise measurements are reported. A new active medium, based on a new glass host with reduced pump-induced birefringence, allowed for negligible performance degradation when using the anisotropic etalon instead of a standard BK7 etalon. A broad tuning range and a relative-intensity-noise peak of about -90 dB/Hz has been achieved     

Serotyping of Streptococcus pneumoniae by coagglutination with 12 pooled antisera

We report on the performance of a recently introduced commercial chessboard method using 12 antisera, in comparison with that of the 55-antiserum panel used in determining the serogroups and types (SGTs) of Streptococcus pneumoniae, both of which were carried out by a coagglutination technique. Of a total of 150 strains of S. pneumoniae studied, 135 (90%) belonged to the SGTs represented in the 23-valent pneumococcal vaccine; of these, 130 (96.3%) were identified as the same SGTs by both typing methods. The remaining five strains showed cross-reactivity with more than two pools by the chessboard method, but could be assigned to a single SGT by the Quellung test. The 96.3% concordance of the chessboard method suggests it can be adopted for determination of the SGTs of S. pneumoniae in laboratories.     

Sequence database searches via de novo peptide sequencing by tandem mass spectrometry

A method is described for searching protein sequence databases using tandem mass spectra of tryptic peptides. The approach uses a de novo sequencing algorithm to derive a short list of possible sequence candidates which serve as query sequences in a subsequent homology-based database search routine. The sequencing algorithm employs a graph theory approach similar to previously described sequencing programs. In addition, amino acid composition, peptide sequence tags and incomplete or ambiguous Edman sequence data can be used to aid in the sequence determinations. Although sequencing of peptides from tandem mass spectra is possible, one of the frequently encountered difficulties is that several alternative sequences can be deduced from one spectrum. Most of the alternative sequences, however, are sufficiently similar for a homology-based sequence database search to be possible. Unfortunately, the available protein sequence database search algorithms (e.g. Blast or FASTA) require a single unambiguous sequence as input. Here we describe how the publicly available FASTA computer program was modified in order to search protein databases more effectively in spite of the ambiguities intrinsic in de novo peptide sequencing algorithms.