Near resonance acoustic scattering from organized schools of juvenile Atlantic bluefin tuna (Thunnus thynnus)

Schools of Atlantic bluefin tuna (Thunnus thynnus) can exhibit highly organized spatial structure within the school. This structure was quantified for dome shaped schools using both aerial imagery collected from a commercial spotter plane and 400 kHz multibeam echo sounder data collected on a fishing vessel in 2009 in Cape Cod Bay, MA. Observations from one school, containing an estimated 263 fish within an approximately ellipsoidal volume of 1900 m3, were used to seed an acoustic model that estimated the school target strength at frequencies between 10 and 2000 Hz. The fish\u27s swimbladder resonance was estimated to occur at approximately 50 Hz. The acoustic model examined single and multiple scattering solutions and also a completely incoherent summation of scattering responses from the fish. Three levels of structure within the school were examined, starting with fish locations that were constrained by the school boundaries but placed according to a Poisson process, then incorporating a constraint on the distance to the nearest neighbor, and finally adding a constraint on the bearing to the nearest neighbor. Results suggest that both multiple scattering and spatial organization within the school should be considered when estimating the target strength of schools similar to the ones considered here

Field calibration of time domain reflectrometry in an Amazonian rainforest soil with variable bulk density: sources of error and influence of land-use.

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Thrombolyse der Arteria cerebri media

Zusammenfassung: In den ersten 3h nach Eintritt eines akuten ischämischen Hirninfarkts ist die intravenöse Thrombolyse (IVT) die evidenzbasierte Therapie (IVT 3-4,5h: "off-label use" mit Einverständnis des Patienten). Die intraarterielle Thrombolyse (IAT) führt in der A.cerebri media (ACM) allerdings häufiger zur Rekanalisation als die IVT. Daher ist die IAT in dafür ausgerüsteten Kliniken ergänzend oder alternativ zur IVT bis zu 6h nach Symptombeginn zu erwäge

Isotropic apparent diffusion coefficient mapping of postnatal cerebral development

Diffusion-weighted imaging (DWI) allows us to image the motion of tissue water. This has been used to demonstrate acute ischaemia. Diffusion imaging is also sensitive to water movement along neuronal tracts. Our objective was to map brain maturation in vivo using maps of apparent diffusion coefficient (ADC). We studied 22children without neurological disease aged between 2 and 720days. MRI was performed at 1.5tesla. Multislice single-shot echoplanar DWI was performed at b 0 and 1000s/mm2. ADC maps were generated automatically and measurements were performed in the basal ganglia, frontal and temporal white matter and the pons. There was a decrease over time in water diffusion in the areas examined, most marked in the frontal (0.887-1.898×10-3mm2/s) and temporal (1.077-1.748×10-3mm2/s)lobes. There was little change, after an initial decrease, in the basal ganglia (0.690-1.336×10-3mm2/s). There was a difference in water diffusion between the anterior (0.687-1.581×10-3mm2/s) and posterior (0.533-1.393×10-3mm2/s) pons. These changes correlate well with those observed in progressive myelination: the increased water content probably reflects incomplete myelination and the decrease with time in water motion reflects the increase in myelinated brai

Development and production of cupuaçu plants (Theobroma grandiflorum) on degraded areas: implications of water relations.

In the study presented here we investigated the development and production of the crop tree Theobroma grandiflorum (in Brazil named "cupuaçu") under varying agro-environments

Comportamento de bananeiras submetidas a diferentes níveis de sombreamento.

Objetiva-se avaliar, por meio de cultivos intercalares e em trilhas na capoeira, a influência dos diferentes níveis de sombreamento na incidência da Sigatoka negra.bitstream/item/89173/1/PA-35-Mirza.pd