Discard composition of the european hake Merluccius merluccius (Linnaeus, 1758) bottom trawl fishery in two areas of the NW Mediterranean Sea, Northern Tyrrhenian Sea and Catalan Sea

1 page, 2 tablesThis study provides data on the discard composition of the European hake bottom trawl fishery in two different areas of the NW Mediterranean, paying special attention to the non-charismatic species. On board sampling was conducted monthly from February to July 2001. The total number of species caught was 189 (163 discarded, 68 commercial) in the northern Tyrrhenian Sea and 246 (207 discarded, 78 commercial) in the Catalan SeaPeer reviewe

Comparación de las capturas de merluza (Merluccius merluccius, L. 1758) Obtenidas con redes experimentales de enmalle de diferentes tipos de malla, en el norte del Mar Tirreno (Mediterráneo noroccintal)

The impact of the gillnet fishery on Merluccius merluccius (European hake) was investigated in the northern Tyrrhenian Sea, western Mediterranean. Four mesh sizes were tested: 53, 62.5, 70 and 82 mm. Horse mackerel (Trachurus trachurus), hake and tub gurnard (Chelidonichthys lucerna) dominated the catches, from a minimum of 89% (82 mm mesh) to a maximum of 97.8% (70 mm) of the biomass caught. Efficiency of the four meshes was not significantly different with respect to the total hake catches. Selectivity on M. merluccius was assessed by Sechin and SELECT methods. Tangling was an important catch modality for hake, as evidenced by the results of the Sechin model which described only the first mode of the size distributions corresponding to the entangled specimens. SELECT showed that the bi-modal function gave the best adjustment to the length-frequency distributions; the modal catch sizes were 33, 39.2, 43.6 and 51 cm total length respectively for the 53, 62.5, 70 and 82 mm mesh sizes. Taking into account the size of first maturity for females (35.1 cm TL), 62.5 mm is the most adequate mesh for exploiting hake as it gives some protection to both immature specimens and large females.Se estudió el impacto de la pesquería con redes de enmalle sobre la merluza, Merluccius merluccius, (merluza europea) en el norte del mar Tirreno, Mediterráneo noroccidental. Se utilizaron cuatro tamaños de malla: 53, 62.5, 70 y 82 mm. Los peces Trachurus trachurus, M. merluccius y Chelidonichthys lucerna dominaron la biomasa capturada, con un mínimo del 89% (malla de 82 mm) y un máximo del 97.8% (malla de 70 mm). La eficiencia de las cuatro mallas no resultó estadísticamente diferente. La selectividad sobre M. merluccius fue estudiada con los métodos Sechin y SELECT. El enredamiento resultó una importante manera de captura, como evidenció el método Sechin, con un buen ajuste sólo para la primera moda de las distribuciones de talla, correspondiente a ejemplares capturados por enmalle. Con el modelo SELECT la función bimodal fue la mejor para describir las estructuras de talla; las tallas modales de captura fueron 33, 39.2, 43.6 y 51 cm de longitud total, para las mallas de 53, 62.5, 70 y 82 mm respectivamente. Teniendo en cuenta la talla de primera madurez, la malla de 62.5 mm es probablemente la más adecuada para la explotación de la merluza, permitiendo una cierta protección tanto de los inmaduros como de las hembras grandes

Energy and Timing Resolution Studies With Silicon Photomultipliers (SiPMs) and 4-Pixel SiPM Matrices for PET

A high performance detector head with matrices of silicon photomultipliers (SiPMs) as photodetectors is under development at the University of Pisa and INFN Pisa. The silicon photomultipliers fabricated at FBK-irst (Trento, Italy) are being evaluated for this purpose. Single SiPM detectors of 1mm x 1 mm size and the first SiPM test matrices composed of four (2 x 2) pixel elements in a common substrate have been tested with LYSO crystals. The energy and timing resolution of single SiPMs have been evaluated, obtaining an energy resolution of 20% FWHM at 511 keV, and a coincidence timing resolution of 1.4 ns FWHM. In addition, the first tests performed with the SiPM matrices prove the feasibility of such devices

Multidetector CT in diagnostic work-up of patients with primary hyperparathyroidism

PURPOSE: This study was performed to evaluate the accuracy of multidetector computed tomography (MDCT) in detecting parathyroid lesions in patients with primary hyperparathyroidism. MATERIALS AND METHODS: We included 60 patients with primary hyperparathyroidism. Preoperative first-line examinations revealed negative and doubtful ultrasound (US) findings in 34 and 26 cases, respectively, and negative, doubtful and positive scintigraphic findings in 19, 20 and 21 cases, respectively. CT findings were compared with the surgical results. RESULTS: CT examination was positive in 35 cases, negative in 15 cases and doubtful in ten cases. Forty out of 60 patients underwent surgery, and 39 lesions (37 adenomas, two primary hyperplasias) were identified. Surgery was negative in two cases. In eight cases, lesions had ectopic location. Surgery confirmed the CT findings in 23 positive cases. In 8/10 doubtful cases, surgery confirmed the location of the lesion in five cases, identified the ectopic location of lesions in two cases, and was negative in one case. In 9/15 cases with negative CT findings, surgery identified the lesion in eight cases. Sensitivity, specificity and diagnostic accuracy values were 78%, 25% and 73%, respectively. CONCLUSIONS: MDCT is an accurate second-line diagnostic technique in the detection of parathyroid lesions, allowing exploration of the entire cervical and mediastinal regions

Characterization of a prototype matrix of Silicon PhotoMultipliers

This work reports on the electrical as well as the optical characterizations of a prototype matrix of Silicon PhotoMultipliers (SiPM). The electrical test consists of the measurement of the static (breakdown voltage, quenching resistance, post-breakdown dark current) as well as the dynamic characteristics (gain, dark count rate). The optical test consists of the estimation of the photon detection efficiency as a function of wavelength as well as operation voltage

UTOFPET: a highly scalable TOF-PET detector concept

We present the design and preliminary simulated performance of a highly scalable TOF-PET detector concept. The UTOFPET project aims at the development of a TOF-PET detector module, with beyond-state-of-the-art performance, that is designed to be well suited for various applications, from brain-dedicated to total-body PET. The UTOFPET detector is based on a continuous scintillator crystal read out by 256 SiPMs, arranged in a 16 × 16 matrix whose outputs are processed by a stack of local processing and data acquisition boards. Initial simulations indicate the feasibility of on-board real-time position and time estimation with a spatial resolution below 0.5 mm FWHM for the whole detector

First results in the application of silicon photomultiplier matrices to small animal PET

A very high resolution small animal PET scanner that employs matrices of silicon photomultipliers as photodetectors is under development at the University of Pisa and INFN Pisa. The first SiPM matrices composed of 16 (4x4) 1mmx1mm pixel elements on a common substrate have been produced at FBK-irst, and are being evaluated for this application. The MAROC2 ASIC developed at LAL-Orsay has been employed for the readout of the SiPM matrices. The devices have been tested with pixelated and continuous LYSO crystals. The results show the good performance of the matrices and lead to the fabrication of matrices with 64 SiPM elements