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Improved Strategies (improved + strategy)
Selected AbstractsEffects of forest harvesting on the occurrence of landslides and debris flows in steep terrain of central JapanEARTH SURFACE PROCESSES AND LANDFORMS, Issue 6 2008Fumitoshi Imaizumi Abstract Landslides and debris flows associated with forest harvesting can cause much destruction and the influence of the timing of harvesting on these mass wasting processes therefore needs to be assessed in order to protect aquatic ecosystems and develop improved strategies for disaster prevention. We examined the effects of forest harvesting on the frequency of landslides and debris flows in the Sanko catchment (central Japan) using nine aerial photo periods covering 1964 to 2003. These photographs showed a mosaic of different forest ages attributable to the rotational management in this area since 1912. Geology and slope gradient are rather uniformly distributed in the Sanko catchment, facilitating assessment of forest harvesting effects on mass wasting without complication of other factors. Trends of new landslides and debris flows correspond to changes in slope stability explained by root strength decay and recovery; the direct impact of clearcutting on landslide occurrence was greatest in forest stands that were clearcut 1 to 10 yr earlier with progressively lesser impacts continuing up to 25 yr after harvesting. Sediment supply rate from landslides in forests clearcut 1 to 10 yr earlier was about 10-fold higher than in control sites. Total landslide volume in forest stands clearcut 0 to 25 yr earlier was 5·8 × 103 m3 km,2 compared with 1·3 × 103 m3 km,2 in clearcuts >25 yr, indicating a fourfold increase compared with control sites during the period when harvesting affected slope stability. Because landslide scars continue to produce sediment after initial failure, sediment supply from landslides continues for 45 yr in the Sanko catchment. To estimate the effect of forest harvesting and subsequent regeneration on the occurrence of mass wasting in other regions, changes in root strength caused by decay and recovery of roots should be investigated for various species and environmental conditions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Phenotype and function of neonatal DCEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 1 2009Fabienne Willems Abstract Newborns face complex physical and immunological changes before and after birth. Although the uterus is a sterile environment for the fetus, it also contains non-self material from the mother. Birth involves the transition from the sterile intra-uterine environment to an environment rich in microbes and requires rapid induction of appropriate responses to control these microbes. In this review we focus on the similarities and differences of human and murine neonatal DC and their reaction to various stimuli. A better understanding of the newborn immune system , in particular, the DC,T-cell interaction , will be beneficial for the development of improved strategies to prevent or treat infections in this vulnerable population and prepare the immune system to cope with allergens and tumors later in life. [source] Selecting discriminant function models for predicting the expected richness of aquatic macroinvertebratesFRESHWATER BIOLOGY, Issue 2 2006JOHN VAN SICKLE Summary 1. The predictive modelling approach to bioassessment estimates the macroinvertebrate assemblage expected at a stream site if it were in a minimally disturbed reference condition. The difference between expected and observed assemblages then measures the departure of the site from reference condition. 2. Most predictive models employ site classification, followed by discriminant function (DF) modelling, to predict the expected assemblage from a suite of environmental variables. Stepwise DF analysis is normally used to choose a single subset of DF predictor variables with a high accuracy for classifying sites. An alternative is to screen all possible combinations of predictor variables, in order to identify several ,best' subsets that yield good overall performance of the predictive model. 3. We applied best-subsets DF analysis to assemblage and environmental data from 199 reference sites in Oregon, U.S.A. Two sets of 66 best DF models containing between one and 14 predictor variables (that is, having model orders from one to 14) were developed, for five-group and 11-group site classifications. 4. Resubstitution classification accuracy of the DF models increased consistently with model order, but cross-validated classification accuracy did not improve beyond seventh or eighth-order models, suggesting that the larger models were overfitted. 5. Overall predictive model performance at model training sites, measured by the root-mean-squared error of the observed/expected species richness ratio, also improved steadily with DF model order. But high-order DF models usually performed poorly at an independent set of validation sites, another sign of model overfitting. 6. Models selected by stepwise DF analysis showed evidence of overfitting and were outperformed by several of the best-subsets models. 7. The group separation strength of a DF model, as measured by Wilks',, was more strongly correlated with overall predictive model performance at training sites than was DF classification accuracy. 8. Our results suggest improved strategies for developing reliable, parsimonious predictive models. We emphasise the value of independent validation data for obtaining a realistic picture of model performance. We also recommend assessing not just one or two, but several, candidate models based on their overall performance as well as the performance of their DF component. 9. We provide links to our free software for stepwise and best-subsets DF analysis. [source] Management of patients with decompensated hepatitis B virus associated cirrhosisLIVER TRANSPLANTATION, Issue S2 2008Fabien Zoulim Key Points 1Hepatitis B virus replication is associated with a severe outcome in patients with decompensated cirrhosis. 2Viral suppression induced by antivirals results in a clinical improvement that allows liver transplantation to be delayed or avoided. 3Early treatment intervention is mandatory in patients with decompensated cirrhosis because of the delay in the restoration of liver functions. 4Lamivudine is no longer the drug of choice because the initial enthusiasm has been tempered by the high rate of resistance development. 5Early add-on therapy with adefovir allows us to rescue lamivudine resistance, but its use may be limited by nephrotoxicity. 6Studies are ongoing with the newer generation of antivirals (telbivudine, tenofovir, entecavir, and emtricitabine) in monotherapy or in combination to determine the best strategy for achieving rapid and prolonged suppression of viral replication. These improved strategies should enhance treatment success enough to obtain clinical stabilization, to delay or prevent the need for transplantation, and to reduce the risk of hepatitis B virus recurrence on the graft. Liver Transpl 14:S1,S7, 2008. © 2008 AASLD. [source] Photodiagnostic techniques for the endoscopic detection of premalignant gastrointestinal lesionsDIGESTIVE ENDOSCOPY, Issue 3 2003Ralph S. DaCosta Considerable attention is given to the clinical diagnosis of gastrointestinal (GI) malignancies as they remain the second leading cause of cancer-associated deaths in developed countries. Detection and intervention at an early stage of preneoplastic development significantly improve patient survival. High-risk assessment of asymptomatic patients is currently performed by strict endoscopic surveillance biopsy protocols aimed at early detection of dysplasia and malignancy. However, poor sensitivity associated with frequent surveillance programs incorporating conventional screening tools, such as white light endoscopy and multiple random biopsy, is a significant limitation. Recent advances in biomedical optics are illuminating new ways to detect premalignant lesions of the GI tract with endoscopy. The present review presents a summary report on the newest developments in modern GI endoscopy, which are based on novel optical endoscopic techniques: fluorescence endoscopic imaging and spectroscopy, Raman spectroscopy, light scattering spectroscopy, optical coherence tomography, chromoendoscopy, confocal fluorescence endoscopy and immunofluorescence endoscopy. Relying on the interaction of light with tissue, these ,state-of-the-art' techniques potentially offer an improved strategy for diagnosis of early mucosal lesions by facilitating targeted excisional biopsies. Furthermore, the prospects of real-time ,optical biopsy' and improved staging of lesions may significantly enhance the endoscopist's ability to detect subtle preneoplastic mucosal changes and lead to curative endoscopic ablation of these lesions. Such advancements within this specialty will be rewarded in the long term with improved patient survival and quality of life. [source] Robust and direct evaluation of J2 in linear elastic fracture mechanics with the X-FEMINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 10 2008G. Legrain Abstract The aim of the present paper is to study the accuracy and the robustness of the evaluation of Jk -integrals in linear elastic fracture mechanics using the extended finite element method (X-FEM) approach. X-FEM is a numerical method based on the partition of unity framework that allows the representation of discontinuity surfaces such as cracks, material inclusions or holes without meshing them explicitly. The main focus in this contribution is to compare various approaches for the numerical evaluation of the J2 -integral. These approaches have been proposed in the context of both classical and enriched finite elements. However, their convergence and the robustness have not yet been studied, which are the goals of this contribution. It is shown that the approaches that were used previously within the enriched finite element context do not converge numerically and that this convergence can be recovered with an improved strategy that is proposed in this paper. Copyright © 2008 John Wiley & Sons, Ltd. [source] An improved strategy for the crystallization of Leishmania mexicana pyruvate kinaseACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2010Hugh P. Morgan The inclusion of novel small molecules in crystallization experiments has provided very encouraging results and this method is now emerging as a promising alternative strategy for crystallizing `problematic' biological macromolecules. These small molecules have the ability to promote lattice formation through stabilizing intermolecular interactions in protein crystals. Here, the use of 1,3,6,8-pyrenetetrasulfonic acid (PTS), which provides a helpful intermolecular bridge between Leishmania mexicana PYK (LmPYK) macromolecules in the crystal, is reported, resulting in the rapid formation of a more stable crystal lattice at neutral pH and greatly improved X-ray diffraction results. The refined structure of the LmPYK,PTS complex revealed the negatively charged PTS molecule to be stacked between positively charged (surface-exposed) arginine side chains from neighbouring LmPYK molecules in the crystal lattice. [source] | ||||||||||