Noninvasive ¹³C-octanoic acid breath test shows delayed gastric emptying in patients with amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by progressive loss of motor neurons. However, ALS has been recognized to also involve non-motor systems. Subclinical involvement of the autonomic system in ALS has been described. The recently developed C-13-octanoic acid breath test allows the noninvasive measurement of gastric emptying. With this new technique we investigated 18 patients with ALS and 14 healthy volunteers. None of the patients had diabetes mellitus or other disorders known to cause autonomic dysfunction. The participants received a solid standard test meal labeled with C-13-octanoic acid. Breath samples were taken at 15-min intervals for 5 h and were analyzed for (CO2)-C-13 by isotope selective nondispersive infrared spectrometry. Gastric emptying peak time (t(peak)) and emptying half time (t(1/2)) were determined. All healthy volunteers displayed normal gastric emptying with a mean emptying t(1/2) of 138 +/- 34 (range 68-172) min. Gastric emptying was delayed (t(1/2) > 160 min) in 15 of 18 patients with ALS. Emptying t(1/2) in ALS patients was 218 +/- 48 (range 126-278) min (p < 0.001). These results are compatible with autonomic involvement in patients with ALS, causing delayed gastric emptying of solids and encouraging the theory that ALS is a multisystem disease rather than a disease of the motor neurons only

Who wants to conserve remaining forest fragments in the Manompana Corridor?

Contiguous forests in Madagascar are continuously converted into forest fragments due to deforestation, and dispersed into landscape mosaics dominated by agriculture. These fragments are of increasing importance for biodiversity conservation as well as for the well being of rural inhabitants, providing a high diversity of timber and non- timber forest products. An increasing number of international projects are therefore trying to preserve remaining forests and to transfer the management of these forests to local communities. However, it is not known how important the preservation of forest fragments is to local people. We therefore explore the importance of forest fragments as a source of cash income to different groups separated by wealth level and access to forest resources. A multi-method research approach was taken, based on score application exercises as well as interviews with individual households and focus groups. Our study site was located at the east coast of Madagascar in the Manompana corridor. Results show that some groups are significantly more interested in the preservation of forest fragments than others. Interest is significantly related to the wealth of local inhabitants as well as to the walking distance between villages and forest resources. Nevertheless, interest in resource preservation does not depend on how important fragments are to local people, but rather on the awareness about resource scarcity.  Résumé En raison d’une forte déforestation sur la côte est de Madagascar, de nombreux massifs forestiers d’un seul tenant et de vastes écosystèmes interconnectés ont été détruits, laissant des fragments de forêts qui s’intègrent dans une mosaïque paysagère dominée par l’agriculture. Ces fragments gagnent en importance. Ils jouent un rôle de premier plan dans les réseaux de biodiversité en assurant un certain niveau de connectivité. Mais les fragments sont essentiels au bien - être de la population locale, fournissant produits et services pour la consommation quotidienne ou donnant accès à un revenu monétaire. Sur un plan global, aussi bien les organisations de protection de la nature que les milieux scientifiques essayent d’endiguer la déforestation. Depuis les années 1996 la politique nationale à Madagascar a généré lois et processus visant à transférer la gestion des ressources forestières de l’Etat aux communautés locales. Cependant, il n’a pas été possible, jusqu’à ce jour, d’atténuer l’ampleur de la destruction et de la fragmentation des forêts pluviales de l’île. Plus encore, à l’heure actuelle la perception de l’importance des fragments de forêts n’est pas connue par la population. Un projet de recherche a été lancé pour contribuer à combler cette lacune, dans le corridor de Manompana, sur la côte. Les buts de ce projet étaient (i) d’explorer l’importance des fragments de forêts pour les revenus monétaires de la population locale et (ii) d’analyser la perception de l’importance des fragments de forêts par la population locale. Les recherches se sont déroulées dans quatre villages situés à des distances différentes du grand massif forestier. La population locale a été répartie en différentes catégories de niveau de vie et en fonction de la distance à parcourir entre les villages et la forêt. Cette approche a permis d’étudier le rôle de la forêt quant aux revenus monétaires des différents groupes de la population. Nous avons également cherché à établir un lien entre l’ampleur des revenus monétaires et un intérêt à conserver les fragments de forêts qui subsistent. Nos méthodes de recherche font recours à des exercices de « scoring », à des discussions avec des groupes ciblés et à des enquêtes de ménages. Il ressort des analyses que certains groupes ont un intérêt à conserver les fragments forestiers. Cet intérêt est significativement lié, d’une part, au niveau de vie de la population, d’autre part, à la distance entre le village et le massif forestier. Cependant, l’intérêt à conserver les fragments de forêts est plus fortement lié à la conscience de la finitude des ressources forestières qu’au montant des revenus monétaires que la population peut tirer des produits forestiers.

Social Constructivism in Learning: Peer Teaching & Learning

Social constructivism is an educational theory that can be applied in collaborative ways to facilitate student peer teaching and learning. University faculty may be unfamiliar with how to plan, structure, and instruct students in peer teaching and learning projects while providing an emotionally supportive environment. This article will identify characteristics of course activities that promote peer teaching and learning. Two student examples of a three-component peer teaching module will be highlighted along with the grading rubric. This article also describes an assignment module that was offered in a face-to-face second-year course in a professional allied health program. These assignment guidelines could also be utilized in general education courses and upper level courses in various colleges within the university. The peer teaching and learning model could also encourage student engagement in online synchronous or asynchronous learning

Comment on "Giant absorption cross section of ultracold neutrons in Gadolinium"

Rauch et al (PRL 83, 4955, 1999) have compared their measurements of the Gd cross section for Ultra-cold neutrons with an exptrapolation of the cross section for thermal neutrons and interpreted the discrepancy in terms of coherence properties of the neutron. We show the extrapolation used is based on a misunderstanding and that coherence properties play no role in absorption.Comment: 2 pages, 1 postscript figure, comment on Rauch et al, PRL 83,4955 (1999

Clustering and Sharing Incentives in BitTorrent Systems

Peer-to-peer protocols play an increasingly instrumental role in Internet content distribution. Consequently, it is important to gain a full understanding of how these protocols behave in practice and how their parameters impact overall performance. We present the first experimental investigation of the peer selection strategy of the popular BitTorrent protocol in an instrumented private torrent. By observing the decisions of more than 40 nodes, we validate three BitTorrent properties that, though widely believed to hold, have not been demonstrated experimentally. These include the clustering of similar-bandwidth peers, the effectiveness of BitTorrent's sharing incentives, and the peers' high average upload utilization. In addition, our results show that BitTorrent's new choking algorithm in seed state provides uniform service to all peers, and that an underprovisioned initial seed leads to the absence of peer clustering and less effective sharing incentives. Based on our observations, we provide guidelines for seed provisioning by content providers, and discuss a tracker protocol extension that addresses an identified limitation of the protocol