Effects of Fiber Angle on the Tensile Properties of Partially Delignified and Densified Wood

Partial delignification and densification provide a pathway to significant improvement in the mechanical performance of wood. In order to elucidate potential effects of this treatment on the mechanical anisotropy of wood, partially delignified and densified spruce wood veneers were characterized at varying degrees of off-axis alignment. While the tensile strength and the modulus of elasticity (MOE) were clearly improved in parallel to the axis of wood fibers, this improvement quickly leveled off at misalignment angles ≥30°. For transverse tensile strength, the performance of alkaline-treated and densified wood was even inferior to that of untreated wood. Microscopic examination revealed the presence of microscopic cracks in treated wood, which are assumed to be responsible for this observation. It is concluded that impaired transverse tensile properties are a weakness of partially delignified and densified wood and should be considered when a potential usage in load-bearing applications is intended.     

Prevalence and diversity of Babesia,Hepatozoon, Ehrlichia,and Bartonella in wild and domestic carnivores from Zambia,Africa

A molecular survey was conducted for several hemoparasites of domestic dogs and three species of wild carnivores from two sites in Zambia. Three Babesia spp. were detected including Babesia felis and Babesia leo in lions (Panthera leo) and a Babesia sp. (similar to Babesia lengau) in spotted hyenas (Crocuta crocuta) and a single lion. All wild dogs (Lycaon pictus) and domestic dogs were negative for Babesia. High prevalences for Hepatozoon were noted in all three wild carnivores (38–61 %) and in domestic dogs (13 %). Significantly higher prevalences were noted in hyenas and wild dogs compared with domestic dogs and lions. All carnivores were PCR negative for Ehrlichia canis, Ehrlichia ewingii, and Bartonella spp. Overall, high prevalences and diversity of Babesia and Hepatozoon were noted in wild carnivores from Zambia. This study is the first molecular characterization of Babesia from any hyena species and is the first report of a Babesia sp. closely related to B. lengau, a parasite previously only reported from cheetahs (Acinonyx jubatus), in lions and hyenas. Although usually benign in wild carnivores, these hemoparasites can be pathogenic under certain circumstances. Importantly, data on vectors for these parasites are lacking, so studies are needed to identify vectors as well as determine transmission routes, infection dynamics, and host specificity of these hemoparasites in wildlife in Africa and also the risk of transmission between domestic animals and wildlife.     

A preliminary investigation of serological tools for the detection of Onchocerca lupi infection in dogs

Onchocerca lupi is a neglected filarioid causing nodular lesions associated with acute or chronic ocular disease in dogs. Despite the recent appraisal of its zoonotic potential, human cases are increasingly reported in the Old and New Worlds. Therefore, the development of accurate tools for the rapid diagnosis of O. lupi infections in dogs is becoming a priority. In this study, we conducted a preliminary investigation aimed at evaluating the usefulness of a commercially available ELISA test for the detection of O. lupi antigens in canine sera. The potential use of this tool for larger epidemiological studies of canine onchocerciasis is discussed.     

Histopathological and clinical findings in renal transplants with Banff type II and III acute cellular rejection without tubulointerstitial infiltrates

According to the Banff guidelines for renal transplants, pure endothelialitis without any tubulointerstitial infiltrates (with the Banff components v?≥?1, i0, t0) has to be called acute cellular rejection (ACR). The pathophysiology of this rare lesion abbreviated as v_only is currently unclear, as well as its clinical, serological, and prognostic implications. Therefore, we conducted this retrospective comparative study. We compared all 23 biopsies with v_only from Hannover Medical School between 2003 and 2010 with 23 matched biopsies with the Banff components v?≥?1, i?≥?1, and t?≥?1 (v_plus) and 23 biopsies with v0, i0, and t0 (v0i0t0). Serological (available in 10, 11, and 14 patients, respectively), histological, and clinical data were compared. Of all biopsies, 0.4 % had findings of v_only. v_only, v_plus, and v0i0t0 only showed minimal differences in the Banff components apart from the cohort-defining components. Endothelialitis in v_only more frequently involved the arcuate arteries than the smaller preglomerular vessels compared to v_plus and vice versa. Combining histopathological data and serological data, v_only more frequently showed criteria for acute humoral rejection than v0i0t0 (albeit not persistent after the Bonferroni–Holm correction in pairwise comparisons), while there was no difference between v_only and v_plus. No difference could be demonstrated regarding clinical presentation at biopsy or outcome. Our results show minimal differences regarding clinical presentation, outcome, and histological features between v_only and v_plus. Patients with v_only should be thoroughly investigated for evidence of acute humoral rejection.     

Online and post-trial feedback differentially affect implicit adaptation to a visuomotor rotation

Multiple motor learning processes can be discriminated in visuomotor rotation paradigms. At least four processes have been proposed: Implicit adaptation updates an internal model based on prediction errors. Model-free reinforcement reinforces actions that achieve task success. Use-dependent learning favors repetition of prior movements, and strategic learning uses explicit knowledge about the task. The current experiment tested whether the processes involved in motor learning differ when visual feedback is altered. Specifically, we hypothesized that online and post-trial feedback would cause different amounts of implicit adaptation. Twenty subjects performed drawing movements to targets under a 45° counterclockwise visuomotor rotation while aiming at a clockwise adjacent target. Subjects received visual feedback via a cursor on a screen. One group saw the cursor throughout the movement (online feedback), while the other only saw the final position after movement execution (post-trial feedback). Both groups initially hit the target by applying the strategy. After 80 trials, subjects with online feedback had drifted in clockwise direction [mean direction error: 15.1° (SD 11.2°)], thus overcompensating the rotation. Subjects with post-trial feedback remained accurate [mean: 0.7° (SD 2.0°), TIME × GROUP: F = 3.926, p = 0.003]. We interpret this overcompensation to reflect implicit adaptation isolated from other mechanisms, because it is driven by prediction error rather than task success (model-free reinforcement) or repetition (use-dependent learning). The current findings extend previous work (e.g., Mazzoni and Krakauer in J Neurosci 26:3642–3645, 2006; Hinder et al. in Exp Brain Res 201:191–207, 2010) and suggest that online feedback promotes more implicit adaptation than does post-trial feedback.