Northern Planing Mills

a poem

Crataegus Crus-galli L Sensu Lato In Southern Ontario: Phenotypic Variation And Variability In Relation To Reproductive Behavior

Crataegus crus-galli L. sensu lato is one of the most widespread groups of hawthorn taxa in eastern North America. Early twentieth century classifications of this group have recognized a considerable degree of dissection into rather narrowly defined species. However, the status of many of these species has been unclear in view of the widespread belief that apomixis is frequent throughout the entire genus. Crataegus crus-galli s. l, was examined at 11 sites across southern Ontario in order to characterize the pattern of morphological variation present in one part of its range. Cluster analyses that employed a selection of resemblance functions and sorting algorithms confirmed the breakdown of the entire complex sampled at these sites into a total of four morphotypes. Two of these are more or less widely distributed and differ from each other most obviously in phenology and stamen number. The other two are much more restricted in their occurrence in Ontario and differ from each other and from the two more common morphotypes in features of flower, foliage and thorn morphology. The degree of multivariate variability exhibited within individual stands of the two common morphotypes was found to be quite low. However, stands of each morphotype were differentiated from one another by a number of correlated flower, fruit and foliage characteristics. Only triploid (pollen-infertile or completely male-sterile) and tetraploid (pollen-fertile) individuals of C. crus-galli s.l. have been found so far in Ontario (x = 17). All four morphotypes produce apparently unreduced, aposporous embryo-sacs. Results of pollination experiments showed that three more or less pollen-fertile morphotypes are self-compatible; in all four agamospermy is evidently pseudogamous. Together, these results suggest that stands of a given morphotype of C. crus-galli s. l. frequently consist largely of sibling individuals. This may result from apomixis and self-fertility, together with certain characteristics of Crataegus seed dispersal. Unnecessarily narrow species concepts applied to this group in the past were probably a result of confounding variation among such stands with that among taxa

The role of mitochondrial DNA in tumorigenesis

Mitochondria are cytoplasmic organelles that are found in almost all mammalian cells. Mitochondria contain their own genome, mitochondrial DNA (mtDNA) that encodes 13 subunits of the electron transfer chain, which is the primary generator of cellular energy. Precise regulation of mtDNA copy number is essential for normal cell function and also the differentiation of stem cells into specialized cell types. Abnormal regulation of mtDNA copy number is associated with cellular dysfunction, mitochondrial disease and more recently cancer. Glioblastoma multiforme (GBM) is a highly malignant subgroup of brain tumors that exhibit similar characteristics to human neural stem cells (hNSCs) including multipotency and the expression of the stem cell factors. It is unknown how GBM cells regulate their mtDNA copy number during differentiation and whether this differs to hNSCs. Furthermore, it is unknown what role mtDNA plays in the gene expression profiles and the tumorigenicity of GBM. To address these issues, GBM cells and hNSCs were differentiated for 28 days and their mtDNA copy number and gene expression were analyzed. In addition, GBM cells were progressively depleted of their mtDNA using the depletion agent, 2'-3'-dideoxycytidine, and their in vivo tumorigenicity assessed. hNSCs and GBM cell lines regulated their copy number in a differential manner during differentiation. hNSCs progressively expanded their mtDNA copy number and adopted a differentiated phenotype whilst GBM cells failed to mimic these processes and their differentiation was incomplete. In addition, progressive depletion of mtDNA copy number in GBM cells resulted in reduced proliferation rates and the down regulation of stem cell factors. In vivo, mtDNA depleted GBM cells formed tumors at a reduced rate and frequency relative to nondepleted cells. These outcomes demonstrate that mtDNA copy number is abnormally regulated in GBM cells and hinders their ability to complete differentiation. The failure of mtDNA-depleted GBM cells to consistently generate tumors strongly suggests that maintenance of mtDNA copy number is essential for GBM cells to be tumorigenic

New Poems

poems by Adam Dickinso

Does a PEEK femoral TKA implant preserve intact femoral surface strains compared with CoCr? A preliminary laboratory study

BACKGROUND: Both the material and geometry of a total knee arthroplasty (TKA) component influence the induced periprosthetic bone strain field. Strain, a measure of the local relative deformation in a structure, corresponds to the mechanical stimulus that governs bone remodeling and is therefore a useful in vitro biomechanical measure for assessing the response of bone to new implant designs and materials. A polyetheretherketone (PEEK) femoral implant has the potential to promote bone strains closer to that of natural bone as a result of its low elastic modulus compared with cobalt-chromium (CoCr).QUESTIONS/PURPOSES: In the present study, we used a Digital Image Correlation (DIC) technique to answer the following question: Does a PEEK TKA femoral component induce a more physiologically normal bone strain distribution than a CoCr component? To achieve this, a DIC test protocol was developed for periprosthetic bone strain assessment using an analog model; the protocol aimed to minimize errors in strain assessment through the selection of appropriate analysis parameters.METHODS: Three synthetic bone femurs were used in this experiment. One was implanted with a CoCr femoral component and one with a PEEK femoral component. The third (unimplanted) femur was intact and used as the physiological reference (control) model. All models were subjected to standing loads on the corresponding polyethylene (ultrahigh-molecular-weight polyethylene) tibial component, and speckle image data were acquired for surface strain analysis using DIC in six repeat tests. The strain in 16 regions of interest on the lateral surface of each of the implanted bone models was plotted for comparison with the corresponding strains in the intact case. A Wilcoxon signed-rank test was used to test for difference at the 5% significance level.RESULTS: Surface analog bone strain after CoCr implantation indicated strain shielding (R2 = 0.6178 with slope, ? = 0.4314) and was lower than the intact case (p = 0.014). The strain after implantation with the PEEK implant deviated less from the intact case (R2 = 0.7972 with slope ? = 0.939) with no difference (p = 0.231).CONCLUSIONS: The strain shielding observed with the contemporary CoCr implant, consistent with clinical bone mineral density change data reported by others, may be reduced by using a PEEK implant.CLINICAL RELEVANCE: This bone analog in vitro study suggests that a PEEK femoral component could transfer more physiologically normal bone strains with a potentially reduced stress shielding effect, which may improve long-term bone preservation. Additional studies including paired cadaver tests are necessary to test the hypothesis further

Measuring Protein Binding to F-actin by Co-sedimentation

Filamentous actin (F-actin) organization within cells is regulated by a large number of actin-binding proteins that control actin nucleation, growth, cross-linking and/or disassembly. This protocol describes a technique – the actin co-sedimentation, or pelleting, assay – to determine whether a protein or protein domain binds F-actin and to measure the affinity of the interaction (i.e., the dissociation equilibrium constant). In this technique, a protein of interest is first incubated with F-actin in solution. Then, differential centrifugation is used to sediment the actin filaments, and the pelleted material is analyzed by SDS-PAGE. If the protein of interest binds F-actin, it will co-sediment with the actin filaments. The products of the binding reaction (i.e., F-actin and the protein of interest) can be quantified to determine the affinity of the interaction. The actin pelleting assay is a straightforward technique for determining if a protein of interest binds F-actin and for assessing how changes to that protein, such as ligand binding, affect its interaction with F-actin

Inferring Nighttime Satellite Imagery from Human Mobility

Nighttime lights satellite imagery has been used for decades as a uniform, global source of data for studying a wide range of socioeconomic factors. Recently, another more terrestrial source is producing data with similarly uniform global coverage: anonymous and aggregated smart phone location. This data, which measures the movement patterns of people and populations rather than the light they produce, could prove just as valuable in decades to come. In fact, since human mobility is far more directly related to the socioeconomic variables being predicted, it has an even greater potential. Additionally, since cell phone locations can be aggregated in real time while preserving individual user privacy, it will be possible to conduct studies that would previously have been impossible because they require data from the present. Of course, it will take quite some time to establish the new techniques necessary to apply human mobility data to problems traditionally studied with satellite imagery and to conceptualize and develop new real time applications. In this study we demonstrate that it is possible to accelerate this process by inferring artificial nighttime satellite imagery from human mobility data, while maintaining a strong differential privacy guarantee. We also show that these artificial maps can be used to infer socioeconomic variables, often with greater accuracy than using actual satellite imagery. Along the way, we find that the relationship between mobility and light emissions is both nonlinear and varies considerably around the globe. Finally, we show that models based on human mobility can significantly improve our understanding of society at a global scale.Comment: 9 pages, 3 figures, presented at the 34th AAAI conference on Artificial Intelligenc

The identification of mitochondrial DNA variants in glioblastoma multiforme

Background: Mitochondrial DNA (mtDNA) encodes key proteins of the electron transfer chain (ETC), which produces ATP through oxidative phosphorylation (OXPHOS) and is essential for cells to perform specialised functions. Tumor-initiating cells use aerobic glycolysis, a combination of glycolysis and low levels of OXPHOS, to promote rapid cell proliferation and tumor growth. Glioblastoma multiforme (GBM) is an aggressively malignant brain tumor and mitochondria have been proposed to play a vital role in GBM tumorigenesis. Results: Using next generation sequencing and high resolution melt analysis, we identified a large number of mtDNA variants within coding and non-coding regions of GBM cell lines and predicted their disease-causing potential through in silico modeling. The frequency of variants was greatest in the D-loop and origin of light strand replication in non-coding regions. ND6 was the most susceptible coding gene to mutation whilst ND4 had the highest frequency of mutation. Both genes encode subunits of complex I of the ETC. These variants were not detected in unaffected brain samples and many have not been previously reported. Depletion of HSR-GBM1 cells to varying degrees of their mtDNA followed by transplantation into immunedeficient mice resulted in the repopulation of the same variants during tumorigenesis. Likewise, de novo variants identified in other GBM cell lines were also incorporated. Nevertheless, ND4 and ND6 were still the most affected genes. We confirmed the presence of these variants in high grade gliomas. Conclusions: These novel variants contribute to GBM by rendering the ETC. partially dysfunctional. This restricts metabolism to anaerobic glycolysis and promotes cell proliferation

The Fire and Smoke Model Evaluation Experiment—A Plan for Integrated, Large Fire–Atmosphere Field Campaigns

The Fire and Smoke Model Evaluation Experiment (FASMEE) is designed to collect integrated observations from large wildland fires and provide evaluation datasets for new models and operational systems. Wildland fire, smoke dispersion, and atmospheric chemistry models have become more sophisticated, and next-generation operational models will require evaluation datasets that are coordinated and comprehensive for their evaluation and advancement. Integrated measurements are required, including ground-based observations of fuels and fire behavior, estimates of fire-emitted heat and emissions fluxes, and observations of near-source micrometeorology, plume properties, smoke dispersion, and atmospheric chemistry. To address these requirements the FASMEE campaign design includes a study plan to guide the suite of required measurements in forested sites representative of many prescribed burning programs in the southeastern United States and increasingly common high-intensity fires in the western United States. Here we provide an overview of the proposed experiment and recommendations for key measurements. The FASMEE study provides a template for additional large-scale experimental campaigns to advance fire science and operational fire and smoke models

Philosophy’s gender gap and argumentative arena: an empirical study

While the empirical evidence pointing to a gender gap in professional, academic philosophy in the English-speaking world is widely accepted, explanations of this gap are less so. In this paper, we aim to make a modest contribution to the literature on the gender gap in academic philosophy by taking a quantitative, corpus-based empirical approach. Since some philosophers have suggested that it may be the argumentative, “logic-chopping,” and “paradox-mongering” nature of academic philosophy that explains the underrepresentation of women in the discipline, our research questions are the following: Do men and women philosophers make different types of arguments in their published works? If so, which ones and with what frequency? Using data mining and text analysis methods, we study a large corpus of philosophical texts mined from the JSTOR database in order to answer these questions empirically. Using indicator words to classify arguments by type, we search through our corpus to find patterns of argumentation. Overall, the results of our empirical study suggest that women philosophers make deductive, inductive, and abductive arguments in their published works just as much as male philosophers do, with no statistically significant differences in the proportions of those arguments relative to each philosopher’s body of work