Ecological and Evolutionary Drivers of Chameleon Forelimb Variation

Skeletal anatomy can vary greatly among individuals of the same family that share a common ancestor. Differences in skeletal anatomy and morphology allow species to be better suited to their environments. The study of skeletal anatomy variation as it pertains to species relatedness and habitat variation can provide useful insight into what may be driving evolutionary patterns among species. Specifically, studying skeletal anatomy of the forelimb could allow for better understanding of how the forelimb anatomy differs based on the arboreality of the species, which allows for better understanding of how habitat can affect morphology. To study the skeletal structure of the forelimb, I used micro computed tomography scans (microCT scans) of various chameleon species to isolate and analyze the skeletal anatomy of the chameleon forelimb. A total of 12 species from 6 genera were used in this analysis and include species with varying levels of arboreality. Measurements of the proximal, medial, and distal widths of the radius, ulna, and metacarpals 1-5, along with the angle of curvature for the radius and the ulna, were taken and analyzed using a principal component analysis (PCA) and phylogenetic logistic regression. Surprisingly, there was no difference between any of the forelimb measurements based on arboreality, either with or without phylogeny. However, qualitative observations of the metacarpals of the forelimb revealed a pattern based on arboreality. All arboreal species had some separation between metacarpals 1-3, whereas terrestrial species had none. The pattern shown in the metacarpals based on arboreality reveal that there seems to be a difference between chameleon forelimbs based on arboreality

Validating performance of automotive materials at high strain rate for improved crash design

This paper investigates sources of performance variability in high velocity testing of automotive crash structures. Sources of variability, or so called noise factors, present in a testing environment, arise from uncertainty in structural properties, joints, boundary conditions and measurement system. A box structure, which is representative of a crash component, is designed and fabricated from a high strength Dual Phase sheet steel. Crush tests are conducted at low and high speed. Such tests intend to validate a component model and material strain rate sensitivity data determined from high speed tensile testing. To support experimental investigations, stochastic modeling is used to investigate the effect of noise factors on crash structure performance variability, and to identify suitable performance measures to validate a component model and material strain rate sensitivity data. The results of the project will enable the measurement of more reliable strain rate sensitivity data for improved crashworthiness predictions of automotive structures

Dynamics of a structured slug population model in the absence of seasonal variation

We develop a novel, nonlinear structured population model for the slug Deroceras reticulatum, a highly significant agricultural pest of great economic impact, in both organic and non-organic settings. In the absence of seasonal variations, we numerically explore the effect of life history traits that are dependent on an individual's size and measures of population biomass. We conduct a systematic exploration of parameter space and highlight the main mechanisms and implications of model design. A major conclusion of this work is that strong size dependent predation significantly adjusts the competitive balance, leading to non-monotonic steady state solutions and slowly decaying transients consisting of distinct generational cycles. Furthermore, we demonstrate how a simple ratio of adult to juvenile biomass can act as a useful diagnostic to distinguish between predated and non-predated environments, and may be useful in agricultural settings

Applying Lean Techniques to Improve the Patient Scheduling Process

A patient's access to healthcare resources often begins with scheduling an appointment with a medical doctor or other provider. An inefficient scheduling system leads to unnecessary delays in providing care for patients and frustration for referring physicians. We used the tools of lean thinking to evaluate our current scheduling system, remove wasteful processes and procedures, and implement a more efficient and effective system. In doing so, we increased the value for our patients, who benefit from more timely access to care and greater satisfaction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73944/1/j.1945-1474.2009.00025.x.pd

On the monophyly of Macrolobium Schreb., an ecologically diverse neotropical tree genus (Fabaceae-Detarioideae)

Premise of research. The Neotropical endemic Macrolobium is one of the most species-rich genera (ca. 75 species) within subfamily Detarioideae (Fabaceae, alternatively Leguminosae). Two sections distinguished by floral morphology have been recognized in the past. Although morphologically diverse, species within the genus share several characters, including a single well-developed petal in adaxial position. However, previous analyses based on plastid markers have suggested that the genus is not monophyletic. We produce the most densely sampled molecular phylogeny of Macrolobium and test the monophyly of the genus and the two sections. Methodology. We analyzed nucleotide sequence data from the nuclear ribosomal internal transcribed spacer (ITS) and plastid (matK, trnG) genomes using Bayesian and maximum likelihood analyses. Pivotal results. The combined analysis retains Macrolobium as a monophyletic genus, with two well-supported subclades corresponding to the two recognized sections. Macrolobium pendulum is the only species placed in a section different from its taxonomic treatment. The relationships recovered with the plastid markers differ slightly from the combined and ITS analyses, but without significant support. Conclusions. Macrolobium is shown to be a monophyletic genus and to contain two well-supported and morphologically defined sections with differing Amazonian and Andean/Central American distributions corresponding to the Gentry pattern. Species are also found to group partly according to habitat preferences and leaf morphology. Both sections contain groups of multijugate and unijugate species, and there appear to have been multiple shifts of this character

Micro-Hall Magnetometry Studies of Thermally Assisted and Pure Quantum Tunneling in Single Molecule Magnet Mn12-Acetate

We have studied the crossover between thermally assisted and pure quantum tunneling in single crystals of high spin (S=10) uniaxial single molecule magnet Mn12-acetate using micro-Hall effect magnetometry. Magnetic hysteresis experiments have been used toinvestigate the energy levels that determine the magnetization reversal as a function of magnetic field and temperature. These experiments demonstrate that the crossover occurs in a narrow (~0.1 K) or broad (~1 K) temperature interval depending on the magnitude and direction of the applied field. For low external fields applied parallel to the easy axis, the energy levels that dominate the tunneling shift abruptly with temperature. In the presence of a transverse field and/or large longitudinal field these energy levels change with temperature more gradually. A comparison of our experimental results with model calculations of this crossover suggest that there are additional mechanisms that enhance the tunneling rate of low lying energy levels and broaden the crossover for small transverse fields.Comment: 5 pages, 5 figure

Structural and chemical investigations of adapted Siemens feed rods for an optimized float zone process

The optimization of the float zone process for industrial application is a promising way to crystallize high purity silicon for high efficiency solar cells with reduced process costs. We investigated two differently produced Siemens rods which should be used as feed material for the float zone process. The aim is to identify and to improve material properties of the feed rods which have a high impact to the float zone process. We show here microstructural and chemical analysis comparing feed rods manufactured under standard conditions and under float zone adapted conditions. To resolve the growth behavior of the grains SEM/EBSD mappings are performed at different positions. TEM analyses are used to investigate the interface region between the mono- and the multicrystalline silicon within the Siemens feed rod. Additionally, drilled cores are cut out from the feed rods containing the region of the slim rod. Afterwards, the drilled cores are crystallized with the float zone process. Finally, carbon and oxygen measurements with FT-IR spectrometry on different positions of the crystallized drilled cores of the Siemens feed rods show the influence of the slim rod material to the float zone process

Influence of slim rod material properties to the Siemens feed rod and the float zone process

The identification and understanding of material properties influencing the float zone process is important to crystallize high purity silicon for high efficiency solar cells. Also the knowledge of minimal requirements to crystallize monocrystalline silicon with the float zone process is of interest from an economic point of view. In the present study, feed rods for the float zone process composed of a central slim rod and the deposited silicon from the Siemens process are investigated. Previous studies have shown that the slim rod has a significant impact on the purity and suitability for further crystallization processes. In particular, contaminations like substitutional carbon and the presence of precipitates as well as the formation of oxide layers play an important role and are investigated in detail. For this purpose different slim rod materials were used in deposition and float zone crystallization experiments. Samples were prepared by cross sectioning and core drilling of Siemens rods, which were recrystallized with the float zone process. Recrystallized drilled cores are analyzed with FT-IR spectrometry concerning the carbon and oxygen content. To estimate the grain growth behavior on the slim rod surface in dependence of the used slim rod material, EBSD mappings inside a SEM are performed on squared and circular slim rods. TEM analysis was used to investigate the presence of an oxide layer at the interface between slim rod and deposited polycrystalline silicon. Additionally the influence of a nitrogen-containing gas atmosphere during the slim rod pulling is investigated by IR microscopy and ToF-SIMS regarding Si3N4 precipitation

Direct observation of membrane insertion by enveloped virus matrix proteins by phosphate displacement

Enveloped virus release is driven by poorly understood proteins that are functional analogs of the coat protein assemblies that mediate intracellular vesicle trafficking. We used differential electron density mapping to detect membrane integration by membrane-bending proteins from five virus families. This demonstrates that virus matrix proteins replace an unexpectedly large portion of the lipid content of the inner membrane face, a generalized feature likely to play a role in reshaping cellular membranes