Leaching is one of the major processes occurring when organic litter is decomposed and is often completed within a few days when litter enters aquatic environments. It is important that leaching is addressed when studying microbial and invertebrate decomposition rates in order to avoid overestimations. The traditional litter bag method that has been used to measure decomposition rates in both terrestrial and aquatic environments has in recent years been challenged by the new and widely adopted tea bag index (TBI). Both methods, however, fail to bring a standardized methodology for separating and recognizing weight losses of litter due to leaching and biotic decomposition. Through a field experiment in two streams with different water discharge, this study has focused on exploring the leaching phase and post-leaching phase of the tea products used in TBI. The results unveiled that 20% of rooibos tea’s and 44% of green tea’s initial weight was lost to leaching within three days (72 hours) of the experiment. After the 72nd hour, both teas remained in a stabilized phase until the end of the experiment (120 hours). Water discharge had no significant effect on neither of the tea-weights during or after the leaching phase. This study recommends that weight loss through the leaching phase are taken into account in future studies and advocate the development of an updated TBI protocol where leaching losses are recognized. If not, overestimations of active decomposition rates will be made and may result in compromised conclusions. / Urlakning är en av de viktigaste processerna som uppstår vid nedbrytning av organiskt material och är ofta slutfört inom några dagar när materialet befinner sig i vattenmiljöer. Det är viktigt att den urlakade massan beräknas när studier fokuserade på nedbrytningshastigeter av mikrober och evertebrater genomförs, detta för att undvika en överestimering av den biotiska aktiviteten. Den traditionella metoden, där torkade växtdelar i påsar, har använts för att mäta nedbrytningshastigheter i både mark- och vattenmiljöer har under de senaste åren utmanats av det nya och allmänt accepterade tepåse-indexet (TBI). Båda metoderna misslyckas dock med att implementera en standardiserad metodik för att separera och uppskatta materialets viktförluster genom urlakning och biotisk nedbrytning. Genom ett fältexperiment i två vattendrag med olika vattenföring har denna studie fokuserat på att undersöka urlakningsfasen och den stabiliserade perioden efter urlakningen hos teprodukterna som används i TBI. Resultaten avslöjade att 20% av rooibos tes och 44% av grönt tes ursprungliga vikt förloras genom urlakning inom tre dagar (72 timmar) av experimentet. Efter den 72:a timmen förblev båda teerna i en stabiliserad fas till slutet av experimentet (120 timmar). Vattenflöde hade ingen signifikant effekt på någon av tetypernas vikter, varken för perioden under eller efter urlakningsfasen. Denna studie rekommenderar att viktminskning genom urlakningsfasen beaktas i framtida studier och förespråkar utvecklingen av ett uppdaterat TBI-protokoll för att inkludera urlakningens påverkan. Om inte, kommer överskattningar av aktiva nedbrytningshastigheter att göras och kan leda till äventyrade slutsatser.

Traumatic brain injury (TBI) affects thousands of people in South Africa. Our knowledge regarding this phenomenon has expanded rapidly and the problematic psychological wellbeing of persons who have been injured through TBI has been well documented. When reviewing the published literature regarding TBI it would appear that the majority originate from a positivist epistemology, quantitative methodology, and focus mainly on cognitive and/or motor ability changes of the injured individual. Furthermore, literature regarding interaction between the injured person and others tend to focus on uninjured family members’ experience of and adaptation to the injured person – generally ignoring the injured person’s experience of others. This study addressed this gap in the literature by making use of a qualitative research design to explore how injured persons' experience of others might contribute to the challenges, other than those related to cognitive and physical changes, persons face following TBI. Specifically, this study investigated whether themes that suggest a "loss of self" could be identified in the narratives of the participants' experiences of others. While not being able to support the idea of “loss of self” in the participants' narratives, there are indications that experiences of others may add to the challenges injured persons face following TBI. / Dissertation (MA (Counselling Psychology))--University of Pretoria, 2007. / Psychology / MA / unrestricted

La préoccupation d’assurer le développement économique a poussé les pays en développement (PED), sortis fraichement de la colonisation, à déclencher un mouvement d’affirmation de la souveraineté sur leurs ressources naturelles devant l’Organisation des Nations Unies (ONU). La contestation a abouti à la résolution 1803 sur la souveraineté permanente sur les ressources naturelles (Résolution 1803)1. La poursuite des revendications pour l’acquisition de la souveraineté économique a débouché sur la naissance de la Charte des droits et des devoirs économiques des États2 (la Charte). Ces deux instruments ont affirmé les droits des PED de régler les différends d’investissements dans leurs juridictions internes, réglementer les activités économiques des étrangers, de nationaliser et d’exproprier les investissements étrangers. Pour les pays développés (PD), l’acquisition de cette souveraineté équivalait à un déclin de la protection et aboutissait au relâchement du caractère contraignant des engagements des PED au regard de la protection des investissements étrangers. C’est dans cet environnement de tension juridique, entre la protection des droits des investisseurs des PD et la protection des intérêts économiques des PED, que les PD ont conçu les traités bilatéraux d’investissement (TBI) pour baliser la protection des intérêts des investisseurs étrangers. La grande innovation de ce régime des TBI consiste à conférer le droit, aux investisseurs étrangers, de poursuivre les pays d’accueil devant le Centre international de règlement des différends en matière d’investissement (CIRDI). Les arbitrages d’investissement qui résultent des réclamations des investisseurs étrangers mettent au-devant de la scène la question de protection de l’intérêt général des PED qui fait l’objet de cette étude. Nous soutenons que ce régime d’investissement, que les PED ont intégré nonobstant leur manque d’expertise pour négocier des TBI prenant en compte leur préoccupation de développement économique, a marginalisé la prise en compte de l’intérêt général dans ces accords. Nous proposons par conséquent deux approches qui, à notre avis, accroitraient la protection de l’intérêt général des PED. L’une est juridique, l’autre institutionnelle. L’approche juridique se compose de trois volets qui convergent tous vers le renforcement de la flexibilité normative des PED. Le premier volet consisterait à introduire dans les TBI des normes de responsabilité sociale des entreprises (RSE). Le deuxième volet s’articulerait sur la délimitation du concept d’investissement afin de réduire son élasticité. Le troisième volet préconise le recours à la marge d’appréciation comme norme de contrôle des interventions réglementaires devant les tribunaux arbitraux du CIRDI. L’approche institutionnelle viserait à accroitre la capacité des PED pour acquérir les connaissances et l’expertise requise pour négocier des TBI et mettre en place des réglementations et politiques d’investissement compatibles avec leurs préoccupations de développement économique.

No description available.

Acrolein is produced endogenously after traumatic brain injury (TBI) and is considered a primary mechanism for secondary damage occurring after TBI. We are using frontal cortex networks derived from mouse embryos and grown on microelectrode arrays in vitro to monitor the spontaneous activity of networks and the changes that occur after acrolein application. Networks exposed to acrolein exhibit a biphasic response profile. An initial increase in network activity, followed by a decrease to 100% activity loss in applications ≥ 50 µM. In applications below 50 µM, acrolein was not toxic but generated activity instability with coordinated but irregular population busts lasting for up to 6 days. The increase in activity preceding toxicity may be linked to a decrease in free spermine, a free radical scavenger that modulates Na+, K+, Ca+ channels as well as NMDA, Kainate, and AMPA receptors. Action potential wave shape analysis after 20 and 30 µM acrolein application revealed a concentration-dependent 15-33% increase in peak to peak amplitude within minutes after exposure. For the same concentrations of acrolein (50 µM), the time required to reach 100% activity loss (IT100) was longer in serum-free medium than in medium with 5% serum, in which IT100 values were reduced by a factor of 4. The greater toxicity in the presence of serum may be explained by acrolein adducts on serum proteins. These reaction products have been shown by other labs to be toxic in cell culture. This in vitro system could be used to expand biochemical analyses such as acrolein-induced spermine depletion and may provide an effective platform for investigating cell culture correlates of secondary TBI damage.

Der endogene adaptive Mechanismus der Hypoxietoleranzentwicklung, als ischemic tolerance bezeichnet, wurde sowohl für Angina-pectoris-Anfälle vor einem folgenden Myokardinfarkt als auch für eine TIA vor einem ischämischen Hirninfarkt beschrieben. Da es Anhalte für eine Minderperfusion des Hirngewebes nach einem Schädelhirntrauma (SHT) gibt, wurde hier untersucht, welche Auswirkung eine cerebrale, ischämische Präkonditionierung (IPC) in Form einer TIA vor dem Trauma oder mikroangiopathische Veränderungen des Hirnparenchyms im CT oder die als neuroprotektiv beschriebene Acetylsalicylsäure auf die Nachblutungsrate bei SHT-Patienten haben. Die Nachblutungsrate in der Gruppe der ischämisch präkonditionierten war signifikant geringer als in der Kontrollgruppe (10,4 % vs. 48,9 %, p<0,001). Auf Grund einer Korrelation der ASS Einnahme mit dem vorliegen einer IPC konnte für diesen Faktor in der multivariaten Analyse kein signifikantes Ergebnis gezeigt werden. Der Glasgow Coma Scale als Maß für das neurologische Defizit bei Entlassung unterschied sich nicht signifikant (12,9 vs. 12,7). Insgesamt traten bei 35,7 % der Patienten Nachblutungen auf, bei initial unauffälligem CT sogar in 54 %. Die Ergebnisse dieser Studie legen nahe, dass eine IPC vor einem SHT eine Rolle spielen könnte. Da jedoch die vorliegenden Daten zeigen, dass eine Nachblutung nicht zwingend mit einem schlechteren neurologischen Outcome einhergeht, müssen noch andere Faktoren existieren, die den klinischen Verlauf eines SHT-Patienten beeinflussen. Diese Studie belegt erneut die Notwendigkeit von Verlaufskontrollen - z.B. mittels CT - da auch bei initial unauffälligem CT-Befund intraparenchymale Blutungen auftreten.

No description available.

No description available.

Moderate-to-severe traumatic brain injury (M/S TBI) is a growing public health concern with significant impact on the cognitive functioning of survivors. Cognitive control and deficits in awareness have been linked to poor recovery and rehabilitation outcomes. One way to research cognitive control is through awareness of errors using electroencephalogram and event-related potentials (ERPs). Both the error-related negativity and the post-error positivity components of the ERP are linked to error awareness and cognitive control processes. Attentional capacity and levels of apathy influence error awareness in those with M/S TBI. There are strong links between awareness, attention, and apathy. However, limited research has examined the role of attention, awareness, and apathy using electrophysiological indices of error awareness to further understand cognitive control in a M/S TBI sample. The current study sought to elucidate the role of apathy in error awareness in those with M/S TBI. Participants included 75 neurologically-healthy controls (divided randomly into two control groups) and 24 individuals with M/S TBI. All participants completed self-report measures of mood, apathy, and executive functioning, as well as a brief neuropsychological battery to measure attention and cognitive ability. To measure awareness, participants completed the error awareness task (EAT), a modified Stroop go/no-go task. Participants signaled awareness of errors committed on the previous trial. The M/S TBI group decreased accuracy while improving or maintaining error awareness compared to controls over time. There were no significant between-group differences for ERN and Pe amplitudes. Levels of apathy in the M/S TBI group were included in three multiple regression analyses predicting proportion of unaware errors, ERN amplitude, and Pe amplitude. Apathy was predictive of error awareness, although not in the predicted direction. Major analyses were replicated using two distinct control groups to determine potential sample effects. Results showed consistent results comparing both control groups to a M/S TBI group. Findings show variable levels of awareness and accuracy over time for those with M/S TBI when compared to controls. Conclusions include varying levels of attention and awareness from the M/S TBI group over time, evidenced by improving awareness of errors when they are happening, but an inability to regulate performance sufficiently to improve accuracy. Levels of apathy are playing a role in error awareness, however, not in predicted directions. The study provides support for the role of attentional impairments in error awareness and encourages future studies to look for varying levels of performance within a given task when using populations linked to elevated levels of apathy and attentional deficits.

Background: Traumatic brain injury (TBI) still remains a difficult disorder to treat. TBI has been associated to chronic neuroinflammation and a high risk for neurodegenerative disorders. Since 2001 between ten to twenty percent of all deployed military members have suffered a combat-related TBI. Nearly twenty to thirty percent of those will experience chronic cognitive, behavioral and somatic symptoms after suffering a TBI. Methods: The objective of this review is to evaluate current literature examining vitamin D as a neurosteroid with protective properties and its clinical relevance after traumatic brain injury. Vitamin D is known to participate in neurobiological processes and genomic regulation in the brain. Clinical and laboratory findings support that vitamin D modulates the immune responses to trauma, diminishes oxidative and toxic damage, and inhibiting activation and progression of the neuroinflammation. Inadequate levels of vitamin D have been identified as a common risk factor for many neurological disorders and have been linked to poorer recovery. Results: This review found compelling evidence to support that the pathology of TBI is closely associated with neuroprotective mechanisms of vitamin D. Low vitamin D levels are common among US active duty military and veterans. The findings strongly suggest that optimizing vitamin D prior to injury could improve the recovery for military members after experiencing a TBI. Vitamin D ameliorates brain damage by modulating neuroinflammation, improving cell survival and down-regulating mechanisms involved in the progression of cell damage following a TBI. However, further studies are needed to evaluate the effects of vitamin D optimization in TBI outcomes.