First High-Speed Video Camera Observations of a Lightning Flash Associated With a Downward Terrestrial Gamma-Ray Flash

In this paper, we present the first high-speed video observation of a cloud-to-ground lightning flash and its associated downward-directed Terrestrial Gamma-ray Flash (TGF). The optical emission of the event was observed by a high-speed video camera running at 40,000 frames per second in conjunction with the Telescope Array Surface Detector, Lightning Mapping Array, interferometer, electric-field fast antenna, and the National Lightning Detection Network. The cloud-to-ground flash associated with the observed TGF was formed by a fast downward leader followed by a very intense return stroke peak current of −154 kA. The TGF occurred while the downward leader was below cloud base, and even when it was halfway in its propagation to ground. The suite of gamma-ray and lightning instruments, timing resolution, and source proximity offer us detailed information and therefore a unique look at the TGF phenomena

<i>In vivo</i> glenohumeral translation under anterior loading in an open-MRI set-up

The evaluation of the glenohumeral joint laxity requires the estimate of displacements of the humeral head centre (HHC) with respect to the glenoid. To the authors׳ knowledge, several studies have been conducted to estimate HHC translations in vivo but data under anterior loading conditions has not been collected yet. Aim of this study was to develop a non-invasive experimental methodology based on magnetic resonance (MR) imaging for the in vivo evaluation of the HHC translations due to an anteriorly directed force. Fourteen asymptomatic shoulders were acquired using a horizontal open MR scanner with the subjects in the supine position both at 15&#176; and 90&#176; of arm abduction with and without an anterior force of 20 N applied at the HHC level. When no load was applied, from 15&#176; to 90&#176; of arm abduction, the HHC moved, anteriorly (1.5&#177;1.3 mm) and superiorly (1.8&#177;1.3 mm) while smaller displacements were observed medio-laterally (0.4&#177;0.7 mm). Under the application of the anterior force the 3D displacement of the HHC with respect to the glenoid was 1.6&#177;1.2 mm and 1.3 &#177;0.7 mm, respectively at 15&#176; and 90&#176; of arm abduction. The level of precision associated to the GHJ translation was less than 0.33 mm along all directions i.e. one order of magnitude smaller than the relevant translations. In conclusion, the MRI-based methodology allowed for the analysis of HHC displacements under conditions of anterior loads within an acceptable level of reliability

Estrutura fina do espermatozóide de Mellita quinquiesperforata Leske (Echinodermata) do litoral norte do Brasil Fine structure of the spermatozoon of the Mellita quinquiesperforata (Echinodermata) of the Northern littoral of Brazil

<abstract language="eng">The fine structure of the spermatozoon in the Mellita quinquiesperforata Leske, 1778 was studied. Collected from the Amazon region, were described by light and transmission electron microscopy. The spermatozoon consisted of a acrosome complex, nucleus, four to six mitochondria, two centrioles and flagellum. The acrosome was composed of a acrosome complex, the acrosomal vesicle and the subacrosomal space. The nucleus are composed by dense material. The middle piece contains 4-6 mitochondria which are arranged around the centrioles, the 9p+0, whose axoneme has the classic 9p+2 microtubular construction