Resource contrast in patterned peatlands increases along a climatic gradient

Copyright by the Ecological Society of America 2010, for personal or educational use only. Article is available at <http://dx.doi.org/10.1890/09-1313.1

Climate tolerances and trait choices shape continental patterns of urban tree biodiversity

Aim: We propose and test a climate tolerance and trait choice hypothesis of urban macroecological variation in which strong filtering associated with low winter temperatures restricts urban biodiversity while weak filtering associated with warmer temperatures and irrigation allows dispersal of species from a global source pool, thereby increasing urban biodiversity. Location: Twenty cities across the USA and Canada. Methods: We examined variation in tree community taxonomic diversity, origins and production of an aesthetic ecosystem service trait in a cross-section of urban field surveys. We correlated urban tree community composition indicators with a key climate restriction, namely mean minimum winter temperature, and evaluated alternative possible drivers: precipitation, summer maximum temperature, population size and the percentage of adults with a college education. Results: Species accumulation curves differed substantially among cities, with observed richness varying from 22 to 122 species. Similarities in tree communities decreased exponentially with increases in climatic differences. Ordination of tree communities showed strong separation among cities with component axes correlated with minimum winter temperature and annual precipitation. Variation among urban tree communities in richness, origins and the provisioning of an aesthetic ecosystem service were all correlated with minimum winter temperature. Main conclusions: The urban climate tolerance and trait choice hypothesis provides a coherent mechanism to explain the large variation among urban tree communities resulting from an interacting environment, species and human decisions. Reconciling the feedbacks between human decision making and biophysical limitations provides a foundation for an urban ecological theory that can better understand and predict the dynamics of other linked biotic communities, associated ecosystem dynamics and resulting services provided to urban residents

Improved Average Complexity for Comparison-Based Sorting

This paper studies the average complexity on the number of comparisons for sorting algorithms. Its information-theoretic lower bound is $n \lg n - 1.4427n + O(\log n)$. For many efficient algorithms, the first $n\lg n$ term is easy to achieve and our focus is on the (negative) constant factor of the linear term. The current best value is $-1.3999$ for the MergeInsertion sort. Our new value is $-1.4106$, narrowing the gap by some $25\%$. An important building block of our algorithm is "two-element insertion," which inserts two numbers $A$ and $B$, $A<B$, into a sorted sequence $T$. This insertion algorithm is still sufficiently simple for rigorous mathematical analysis and works well for a certain range of the length of $T$ for which the simple binary insertion does not, thus allowing us to take a complementary approach with the binary insertion.Comment: 21 pages, 2 figure

Modelling disease activity in juvenile dermatomyositis: A Bayesian approach

Juvenile dermatomyositis is the most common form of the juvenile idiopathic inflammatory myopathies characterised by muscle and skin inflammation, leading to symmetric proximal muscle weakness and cutaneous symptoms. It has a fluctuating course and varying prognosis. In a Bayesian framework, we develop a joint model for four longitudinal outcomes, which accounts for within individual variability as well as inter-individual variability. Correlations among the outcome variables are introduced through a subject-specific random effect. Moreover, we exploit an approach similar to a hurdle model to account for excess of a specific outcome in the response. Clinical markers and symptoms are used as covariates in a regression set-up. Data from an ongoing observational cohort study are available, providing information on 340 subjects, who contributed 2725 clinical visits. The model shows good performance and yields efficient estimations of model parameters, as well as accurate predictions of the disease activity parameters, corresponding well to observed clinical patterns over time. The posterior distribution of the by-subject random intercepts shows a substantial correlation between two of the outcome variables. A subset of clinical markers and symptoms are identified as associated with disease activity. These findings have the potential to influence clinical practice as they can be used to stratify patients according to their prognosis and guide treatment decisions, as well as contribute to on-going research about the most relevant outcome markers for patients affected by juvenile dermatomyositis

Professional Profile, Legal Obligations, And Conduct Of Orthodontists In Terms Of Litigation Prevention

Orthodontic treatment requires ethical and legal attitudes from professionals since the first contact with the patient. Thus, this study assessed professional profile, legal obligations in provision of care, and the conduct of orthodontists in terms of litigation prevention during their professional practice. Questionnaires were emailed to 1653 Brazilian orthodontists, asking for information such as: age, gender, graduate orthodontic education, time of work in orthodontics, place of graduate education, time since graduation, and information regarding the legal criteria involved in the orthodontic treatment. Data were tabulated using absolute and relative frequencies. The chi-square test (p<0.05) was used to verify the association among nominal qualitative variables. Only 163 orthodontists participated in the study, wherein men represented 60.5% and women 39.5% of the sample. It was clear that professionals most recently graduated are the ones that mostly use the care provision contract, and the ones that mostly request teleradiographs. The female gender offered more treatment options, clarified the estimated treatment time more often, and was less involved in legal issues. On the other hand, the male gender requested cephalometry more often. Most professionals request the control radiograph, and all of them file the medical records of patients. Few professionals use the professional liability insurance. The results of the present study indicate a highly heterogeneous professional profile. The female gender dominates the field of expertise, and they seem to be more careful regarding legal obligations.3282983

System design of a quadrupedal galloping machine

In this paper we present the system design of a machine that we have constructed to study a quadrupedal gallop gait. The gallop gait is the preferred high-speed gait of most cursorial quadrupeds. To gallop, an animal must generate ballistic trajectories with characteristic strong impacts, coordinate leg movements with asymmetric footfall phasing, and effectively use compliant members, all the while maintaining dynamic stability. In this paper we seek to further understand the primary biological features necessary for galloping by building and testing a robotic quadruped similar in size to a large goat or antelope. These features include high-speed actuation, energy storage, on-line learning control, and high-performance attitude sensing. Because body dynamics are primarily influenced by the impulses delivered by the legs, the successful design and control of single leg energetics is a major focus of this work. The leg stores energy during flight by adding tension to a spring acting across an articulated knee. During stance, the spring energy is quickly released using a novel capstan design. As a precursor to quadruped control, two intelligent strategies have been developed for verification on a one-legged system. The Levenberg-Marquardt on-line learning method is applied to a simple heuristic controller and provides good control over height and forward velocity. Direct adaptive fuzzy control, which requires no system modeling but is more computationally expensive, exhibits better response. Using these techniques we have been successful in operating one leg at speeds necessary for a dynamic gallop of a machine of this scale. Another necessary component of quadruped locomotion is high-resolution and high-bandwidth attitude sensing. The large ground impact accelerations, which cause problems for any single traditional sensor, are overcome through the use of an inertial sensing approach using updates from optical sensors and vehicle kinematics

Excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV:A look behind the nuclear surface

Data for the excitation of the 21+ and 22+ states in the 88Sr(p, p′) reaction at 25 and 31 MeV indicate substantial contributions from the interior of the nucleus, Microscopic DWBA calculations reproduce this and yield a fair description of the data. A detailed description, especially of the 22+ state, is sensitive to the effective nucleon-nucleon interaction used and the non-locality of the optical potential, which are insufficiently known at present

Biomimetic heterogenous elastic tissue development

There is an unmet need for artificial tissue to address current limitations with donor organs and problems with donor site morbidity. Despite the success with sophisticated tissue engineering endeavours, which employ cells as building blocks, they are limited to dedicated labs suitable for cell culture, with associated high costs and long tissue maturation times before available for clinical use. Direct 3D printing presents rapid, bespoke, acellular solutions for skull and bone repair or replacement, and can potentially address the need for elastic tissue, which is a major constituent of smooth muscle, cartilage, ligaments and connective tissue that support organs. Thermoplastic polyurethanes are one of the most versatile elastomeric polymers. Their segmented block copolymeric nature, comprising of hard and soft segments allows for an almost limitless potential to control physical properties and mechanical behaviour. Here we show direct 3D printing of biocompatible thermoplastic polyurethanes with Fused Deposition Modelling, with a view to presenting cell independent in-situ tissue substitutes. This method can expeditiously and economically produce heterogenous, biomimetic elastic tissue substitutes with controlled porosity to potentially facilitate vascularisation. The flexibility of this application is shown here with tubular constructs as exemplars. We demonstrate how these 3D printed constructs can be post-processed to incorporate bioactive molecules. This efficacious strategy, when combined with the privileges of digital healthcare, can be used to produce bespoke elastic tissue substitutes in-situ, independent of extensive cell culture and may be developed as a point-of-care therapy approach