Development of behavioral rules for upstream orientation of fish in confined space.

Improving the effectiveness of fishways requires a better understanding of fish behavior near hydraulic structures, especially of upstream orientation. One of the most promising approaches to this problem is the use of model behavioral rules. We developed a three-dimensional individual-based model based on observed brown trout (Salmo trutta fario) movement in a laboratory flume and tested it against two hydraulically different flume setups. We used the model to examine which of five behavioral rule versions would best explain upstream trout orientation. The versions differed in the stimulus for swim angle selection. The baseline stimulus was positive rheotaxis with a random component. It was supplemented by attraction towards either lower velocity magnitude, constant turbulence kinetic energy, increased flow acceleration, or shorter wall distance. We found that the baseline stimulus version already explained large parts of the observed behavior. Mixed results for velocity magnitude, turbulence kinetic energy, and flow acceleration indicated that the brown trout did not orient primarily by means of these flow features. The wall distance version produced significantly improved results, suggesting that wall distance was the dominant orientation stimulus for brown trout in our hydraulic conditions. The absolute root mean square error (RMSE) was small for the best parameter set (RMSE = 9 for setup 1, RMSE = 6 for setup 2). Our best explanation for these results is dominance of the visual sense favored by absence of challenging hydraulic stimuli. We conclude that under similar conditions (moderate flow and visible walls), wall distance could be a relevant stimulus in confined space, particularly for fishway studies and design in IBMs, laboratory, and the field.

Clinical findings and management of patients with meningitis with an emphasis on Haemophilus influenzae meningitis in rural Tanzania.

INTRODUCTION: The spectrum of meningitis pathogens differs depending on the age of patients and the geographic region, amongst other. Although meningitis vaccination programs have led to the reduction of incidence rates, an imbalance between low- and high-income countries still exists. METHODS: In a hospital-based study in rural northern Tanzania, we consecutively recruited patients with confirmed meningitis and described their clinical and laboratory characteristics. RESULTS: A total of 136 patients with meningitis were included. Fever (85%), meningism (63%) and impairment of consciousness (33%) were the most frequent clinical symptoms/signs. Nearly 10% of all patients tested were positive for malaria. The majority of the patients with bacterial meningitis (39%), especially those under 5years of age, were confirmed to be infected with Haemophilus influenzae (26%), Streptococcus pneumoniae (19%) and Neisseria meningitidis (15%). Haemophilus influenzae represented the dominant causative organism in children under 2years of age. CONCLUSION: Our study emphasizes the importance of recognizing warning symptoms like fever, meningism and impairment of consciousness, implementing laboratory tests to determine responsible pathogens and evaluating differential diagnoses in patients with meningitis in sub-Saharan Africa. It also shows that Haemophilus influenza meningitis is still an important cause for meningitis in the young, most probabaly due to lack of appropriate vaccination coverage.

Profiling of isoflavonoids in Iris germanica rhizome extracts by microprobe NMR and HPLC-PDA-MS analysis.

Lipophilic and polar extracts of iris rhizomes (Iris germanica) were submitted to a phytochemical profiling by a combination of HPLC-PDA-MS and semi-preparative HPLC/off-line microprobe NMR measurements. A total of 20 compounds were purified in sub-milligram to milligram amounts via two successive chromatographic steps. They were identified as isoflavones, isoflavone glycosides and acetovanillone by analysis of on-line MS and PDA, and off-line NMR data. A new isoflavone glycoside, iriflogenin-4'-O-gentiobioside, was subsequently isolated at preparative scale for full chemical characterization. This study demonstrates the applicability of the HPLC/off-line microprobe NMR approach as a robust means for rapid phytochemical profiling of plant extracts.