113 research outputs found
Patterns of wood carbon dioxide efflux across a 2,000-m elevation transect in an Andean moist forest
During a 1-year measurement period, we recorded the CO2 efflux from stems (RS) and coarse woody roots (RR) of 13â20 common tree species at three study sites at 1,050, 1,890 and 3,050Â m a.s.l. in an Andean moist forest. The objective of this work was to study elevation changes of woody tissue CO2 efflux and the relationship to climate variation, site characteristics and growth. Furthermore, we aim to provide insights into important respirationâproductivity relationships of a little studied tropical vegetation type. We expected RS and RR to vary with dry and humid season conditions. We further expected RS to vary more than RR due to a more stable soil than air temperature regime. Seasonal variation in woody tissue CO2 efflux was indeed mainly attributable to stems. At the same time, temperature played only a small role in triggering variations in RS. At stand level, the ratio of C release (g C mâ2 ground area yearâ1) between stems and roots varied from 4:1 at 1,050Â m to 1:1 at 3,050Â m, indicating the increasing prevalence of root activity at high elevations. The fraction of growth respiration from total respiration varied between 10 (3,050Â m) and 14% (1,050Â m) for stems and between 5 (1,050Â m) and 30% (3,050Â m) for roots. Our results show that respiratory activity and hence productivity is not driven by low temperatures towards higher elevations in this tropical montane forest. We suggest that future studies should examine the limitation of carbohydrate supply from leaves as a driver for the changes in respiratory activity with elevation
Physical education undergraduate studentsâ perceptions of their learning using the jigsaw learning method
Recognising the limited research around the use of cooperative learning in higher education, this case study sought to explore physical education studentsâ perceptions of learning using the jigsaw learning method. It examined the impact of two different aesthetic activities and two different groupings on studentsâ perceptions of their learning. A purposive sample of 36 third-year undergraduates was selected for the study. Data were collected using focus group interviews and reflective journals. Inductive analysis illustrated studentsâ perceptions of their own and othersâ abilities, studentsâ empathy towards their peers, and how their perceptions of gymnastics and dance impacted on their perceptions of learning. Students felt that heterogeneous and friendship groupings have the potential to encourage high-order social and cognitive learning. However, those students with limited psychomotor abilities appear to be better served in friendship groupings to facilitate such learning. Students also favoured the âstructuredâ nature of gymnastics in comparison to dance for their own teaching and learning purposes. Irrespective of aesthetic activity or grouping utilised, students felt their psychomotor learning was limited. It is recommended that university staff consider using a mixture of groupings with a single cohort dependent on the practical ability of students and the use of more âstructuredâ activities. In doing so, studentsâ perceptions of their social, cognitive and psychomotor learning may improve and thereby encourage greater and more effective use of this innovative method in schools
'Omic approaches to preventing or managing metastatic breast cancer
Early detection of metastasis-prone breast cancers and characterization of residual metastatic cancers are important in efforts to improve management of breast cancer. Applications of genome-scale molecular analysis technologies are making these complementary approaches possible by revealing molecular features uniquely associated with metastatic disease. Assays that reveal these molecular features will facilitate development of anatomic, histological and blood-based strategies that may enable detection prior to metastatic spread. Knowledge of these features also will guide development of therapeutic strategies that can be applied when metastatic disease burden is low, thereby increasing the probability of a curative response
Search for neutral heavy leptons produced in decays
Weak isosinglet Neutral Heavy Leptons (Îœm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 Ă 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived Îœm production giving monojet or acollinear jet topologies, and for long-lived Îœm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 â ÎœmÎœÌ) of about 1.3 Ă 10-6 at 95% confidence level for Îœm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the Îœm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos. © Springer-Verlag 1997
Quantitative analysis of computed tomography images and early detection of cerebral edema for pediatric traumatic brain injury patients: retrospective study
Comprehensive molecular characterization of the hippo signaling pathway in cancer
Hippo signaling has been recognized as a key tumor suppressor pathway. Here, we perform a comprehensive molecular characterization of 19 Hippo core genes in 9,125 tumor samples across 33 cancer types using multidimensional âomicâ data from The Cancer Genome Atlas. We identify somatic drivers among Hippo genes and the related microRNA (miRNA) regulators, and using functional genomic approaches, we experimentally characterize YAP and TAZ mutation effects and miR-590 and miR-200a regulation for TAZ. Hippo pathway activity is best characterized by a YAP/TAZ transcriptional target signature of 22 genes, which shows robust prognostic power across cancer types. Our elastic-net integrated modeling further reveals cancer-type-specific pathway regulators and associated cancer drivers. Our results highlight the importance of Hippo signaling in squamous cell cancers, characterized by frequent amplification of YAP/TAZ, high expression heterogeneity, and significant prognostic patterns. This study represents a systems-biology approach to characterizing key cancer signaling pathways in the post-genomic era
Enforcing the General Planar Motion Model : Bundle Adjustment for Planar Scenes
In this paper we consider the case of planar motion, where a mobile platform equipped with two cameras moves freely on a planar surface. The cameras are assumed to be directed towards the floor, as well as being connected by a rigid body motion, which constrains the relative motion of the cameras and introduces new geometric constraints. In the existing literature, there are several algorithms available to obtain planar motion compatible homographies. These methods, however, do not minimise a physically meaningful quantity, which may lead to issues when tracking the mobile platform globally. As a remedy, we propose a bundle adjustment algorithm tailored for the specific problem geometry. Due to the new constrained model, general bundle adjustment frameworks, compatible with the standard six degree of freedom model, are not directly applicable, and we propose an efficient method to reduce the computational complexity, by utilising the sparse structure of the problem. We explore the impact of different polynomial solvers on synthetic data, and highlight various trade-offs between speed and accuracy. Furthermore, on real data, the proposed method shows an improvement compared to generic methods not enforcing the general planar motion model
Video-Based 3D Reconstruction, Laparoscope Localization and Deformation Recovery for Abdominal Minimally Invasive Surgery: A Survey
Background
The intra-operative three-dimensional (3D) structure of tissue organs and laparoscope motion are the basis for many tasks in computer-assisted surgery (CAS), such as safe surgical navigation and registration of pre-operative and intra-operative data for soft tissues. Methods
This article provides a literature review on laparoscopic video-based intra-operative techniques of 3D surface reconstruction, laparoscope localization and tissue deformation recovery for abdominal minimally invasive surgery (MIS). Results
This article introduces a classification scheme based on the motions of a laparoscope and the motions of tissues. In each category, comprehensive discussion is provided on the evolution of both classic and state-of-the-art methods. Conclusions
Video-based approaches have many advantages, such as providing intra-operative information without introducing extra hardware to the current surgical platform. However, an extensive discussion on this important topic is still lacking. This survey paper is therefore beneficial for researchers in this field
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