Joining of thirty three percent by weight random glass fibre reinforced polystyrene using variable frequency microwave

[Abstract]: This paper extends the range of applications for Variable Frequency Microwave (VFM) (2 – 18 GHz) facilities to joining thirty three percent by weight glass fibre reinforced polystyrene composite [PS/GF (33%)]. With a given power level, the composite was exposed to various exposure times to microwave irradiation. The primer or coupling agent used was 5-minute two-part adhesive containing 100% liquid epoxy and 8% amine, i.e. Araldite, which was more readily microwave reactive than the composite itself. Bond strengths of the joints were lap shear tested and results were compared with those obtained using fixed frequency (2.45 GHz) microwave processing. The VFMF was operated under software control, which provided automatic data logging facilities. The maximum lap shear bond strength of joint was 430 N/cm2 using variable frequency microwave facility while that obtained by fixed frequency microwave configuration was only 331 N/cm2. The former is nearly 30% stronger than the latter

Einfluss der Kleegras-Nutzung auf die N-Versorgung und Ertragsleistung marktfähiger Folgefrüchte

Im Rahmen des Forschungsschwerpunktes „Ökologischer Landbau und extensive Landnutzungssysteme“ wurden auf dem Versuchsgut für Ökologischen Landbau der Universität Kiel (Lindhof) in den Jahren 1999-2003 Untersuchungen zur Optimierung des N-Transfers vom Kleegras zur Folgefrucht Getreide durchgeführt. Als Versuchsfaktoren wurde die Kleegras-Bewirtschaftung (3x Schnittgutabfuhr, 2x Schnittgutabfuhr + 1x Mulchen, 3x Mulchen), die Umbruchart (Pflug, Fräse + Pflug), der Umbruchtermin (Herbstumbruch/ Winterweizen, Frühjahrsumbruch/ Sommerweizen bzw. Hafer) und eine organische Düngung zu EC 45 (0, 75 kg N/ha) geprüft. Die Kleegras-Bewirtschaftung beeinflusste nicht den Kornertrag von Winterweizen (Ø 48,4 dt/ha), Sommerweizen (Ø 46,6 dt/ha) und Hafer (Ø 58,5 dt/ha). Dagegen bewirkte die Kleegras-Stoppelbearbeitung eine Ertragssteigerung beim Sommerweizen (+ 3,9 dt/ha) und die Gülledüngung einen positiven Effekt auf den Kornertrag von Winterweizen (+ 5,9 dt/ha). Im Vergleich zur Kleegras-Überwinterung erhöhte der Herbstumbruch die NO3-N-Fracht im Sickerwasser um 16 kg N/ha. Die vollständige Schnittgutabfuhr reduzierte sowohl bei Kleegras-Überwinterung als auch bei Herbstumbruch die NO3-N-Fracht im Sickerwasser. In der zweiten Sickerwasserperiode nach der Kleegras-Bewirtschaftung war die NO3-N-Fracht im Sickerwasser nach Sommerweizen höher als nach Winterweizen und konnte durch den Anbau der Zwischenfrucht Gelbsenf signifikant gesenkt werden

Vestibular and Attractor Network Basis of the Head Direction Cell Signal in Subcortical Circuits

Accurate navigation depends on a network of neural systems that encode the moment-to-moment changes in an animal\u27s directional orientation and location in space. Within this navigation system are head direction (HD) cells, which fire persistently when an animal\u27s head is pointed in a particular direction (Sharp et al., 2001a; Taube, 2007). HD cells are widely thought to underlie an animal\u27s sense of spatial orientation, and research over the last 25+ years has revealed that this robust spatial signal is widely distributed across subcortical and cortical limbic areas. The purpose of the present review is to summarize some of the recent studies arguing that the origin of the HD signal resides subcortically, specifically within the reciprocal connections of the dorsal tegmental and lateral mammillary nuclei. Furthermore, we review recent work identifying “bursting” cellular activity in the HD cell circuit after lesions of the vestibular system, and relate these observations to the long held view that attractor network mechanisms underlie HD signal generation. Finally, we summarize anatomical and physiological work suggesting that this attractor network architecture may reside within the tegmento-mammillary circuit

Is navigation in virtual reality with fMRI really navigation?

Identifying the neural mechanisms underlying spatial orientation and navigation has long posed a challenge for researchers. Multiple approaches incorporating a variety of techniques and animal models have been used to address this issue. More recently, virtual navigation has become a popular tool for understanding navigational processes. Although combining this technique with functional imaging can provide important information on many aspects of spatial navigation, it is important to recognize some of the limitations these techniques have for gaining a complete understanding of the neural mechanisms of navigation. Foremost among these is that, when participants perform a virtual navigation task in a scanner, they are lying motionless in a supine position while viewing a video monitor. Here, we provide evidence that spatial orientation and navigation rely to a large extent on locomotion and its accompanying activation of motor, vestibular, and proprioceptive systems. Researchers should therefore consider the impact on the absence of these motion-based systems when interpreting virtual navigation/functional imaging experiments to achieve a more accurate understanding of the mechanisms underlying navigation. © 2013 Massachusetts Institute of Technology

Head Direction Cells and Episodic Spatial Information in Rats without a Hippocampus

To successfully navigate through the environment animals rely on information concerning their directional heading and location. Many cells within the postsubiculum and anterior thalamus discharge as a function of the animal’s head direction (HD), while many cells in the hippocampus discharge in relation to the animal’s location. We placed lesions in the hippocampus and recorded from HD cells in the postsubiculum and anterior thalamus. Lesions of the hippocampus did not disrupt the HD cell signal in either brain area, indicating that the HD cell signal must be generated by structures external to the hippocampus. In addition, each cell’s preferred firing direction remained stable across days when the lesioned animal was placed into a novel environment. This stability appeared to weaken after several weeks of nonexposure to the new enclosure for two out of five animals, and subsequently recorded cells from these two animals established a new angular relationship between the familiar and novel environments. Our results suggest that extra-hippocampal structures are capable of creating and maintaining a novel representation of the animal’s environmental context. This representation shares features in common with mnemonic processes involving episodic memory that until now were assumed to require an intact hippocampus

Towards quantitative prediction of proteasomal digestion patterns of proteins

We discuss the problem of proteasomal degradation of proteins. Though proteasomes are important for all aspects of the cellular metabolism, some details of the physical mechanism of the process remain unknown. We introduce a stochastic model of the proteasomal degradation of proteins, which accounts for the protein translocation and the topology of the positioning of cleavage centers of a proteasome from first principles. For this model we develop the mathematical description based on a master-equation and techniques for reconstruction of the cleavage specificity inherent to proteins and the proteasomal translocation rates, which are a property of the proteasome specie, from mass spectroscopy data on digestion patterns. With these properties determined, one can quantitatively predict digestion patterns for new experimental set-ups. Additionally we design an experimental set-up for a synthetic polypeptide with a periodic sequence of amino acids, which enables especially reliable determination of translocation rates.Comment: 14 pages, 4 figures, submitted to J. Stat. Mech. (Special issue for proceedings of 5th Intl. Conf. on Unsolved Problems on Noise and Fluctuations in Physics, Biology & High Technology, Lyon (France), June 2-6, 2008

Alcoóis lineares em solos arqueológicos da Amazônia.

Pôster

Structural Features of Condensed Tannins Influence Their Antimethanogenic Potential in Forage Plants

Despite years of research on the antimethanogenic potential of condensed tannins (CT), their large-scale application is inhibited by a substantial variability in previous studies with regards to their impact on ruminant nutrition. This variability mainly results from the complexity of CT structures, and their impact on methane emissions is often unaccounted for. Hence, this study (a) evaluated the variability in antimethanogenic potential across six forage species, (b) linked methane emissions to tannin activity, and (c) determined the impact of CT structural features on methane abatement. Six forage species were grown in a greenhouse under controlled environmental conditions, namely, sainfoin (Onobrychis viciifolia), birdsfoot trefoil (Lotus corniculatus), big trefoil (Lotus pedunculatus), plantain (Plantaga lanceolata), sulla (Hedysarum coronarium) and lucerne (Medicago sativa). The plants were harvested at the flowering stage and leaf samples were analysed for chemical composition, condensed tannin concentration and structural features, before being incubated in rumen fluid for 24 hours. Lucerne was used as negative control (without tannins) and an additional polyethylene glycol (PEG) treatment was included, to inactivate tannins and link any effect on fermentation characteristics to tannin activity only. A strong variability across the species (P\u3c 0.0001) was observed on methane emissions. Sulla had the highest antimethanogenic potential and decreased methane emissions by 47% compared to lucerne. All species rich in CTs decreased both methane and total gas production, yet the PEG treatment did not alter the methane proportion in the total gas produced. In addition to CT concentration (R= -0.78), methane emissions were found to be negatively correlated with the CT structural features, prodelphinidin percentage (R= -0.6) and mean degree of polymerisation (R= -0.57). This study demonstrated that antimethanogenic potential of forages depends on CT concentration as well as on structural features and incorporating them in the studies can efficiently assess their impact on ruminant nutrition