3,242 research outputs found
The resistance of cortical bone tissue to failure under cyclic loading is reduced with alendronate
No full textBisphosphonates are the most prescribed preventative treatment for osteoporosis. However, their long-term use has recently been associated with atypical fractures of cortical bone in patients who present with low-energy induced breaks of unclear pathophysiology. The effects of bisphosphonates on the mechanical properties of cortical bone have been exclusively studied under simple, monotonic, quasi-static loading. This study examined the cyclic fatigue properties of bisphosphonate-treated cortical bone at a level in which tissue damage initiates and is accumulated prior to frank fracture in low-energy situations. Physiologically relevant, dynamic, 4-point bending applied to beams (1.5 mm × 0.5 mm × 10 mm) machined from dog rib (n=12/group) demonstrated mechanical failure and micro-architectural features that were dependent on drug dose (3 groups: 0, 0.2, 1.0mg/kg/day; alendronate [ALN] for 3 years) with cortical bone tissue elastic modulus (initial cycles of loading) reduced by 21% (p<0.001) and fatigue life (number of cycles to failure) reduced in a stress-life approach by greater than 3-fold with ALN1.0 (p<0.05). While not affecting the number of osteons, ALN treatment reduced other features associated with bone remodeling, such as the size of osteons (-14%; ALN1.0: 10.5±1.8, VEH: 12.2±1.6, ×10(3) μm2; p<0.01) and the density of osteocyte lacunae (-20%; ALN1.0: 11.4±3.3, VEH: 14.3±3.6, ×10(2) #/mm2; p<0.05). Furthermore, the osteocyte lacunar density was directly proportional to initial elastic modulus when the groups were pooled (R=0.54, p<0.01). These findings suggest that the structural components normally contributing to healthy cortical bone tissue are altered by high-dose ALN treatment and contribute to reduced mechanical properties under cyclic loading conditions.NOTICE: this is the author's version of a work that was accepted for publication in Bone. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Bone, Volume 64 (July 2014) DOI: 10.1016/j.bone.2014.03.045Peer reviewe
American Society of Biomechanics Journal of Biomechanics Award 2013: Cortical bone tissue mechanical quality and biological mechanisms possibly underlying atypical fractures
No full textThe biomechanics literature contains many well-understood mechanisms behind typical fracture types that have important roles in treatment planning. The recent association of "atypical" fractures with long-term use of drugs designed to prevent osteoporosis has renewed interest in the effects of agents on bone tissue-level quality. While this class of fracture was recognized prior to the introduction of the anti-resorptive bisphosphonate drugs and recently likened to stress fractures, the mechanism(s) that lead to atypical fractures have not been definitively identified. Thus, a causal relationship between these drugs and atypical fracture has not been established. Physicians, bioengineers and others interested in the biomechanics of bone are working to improve fracture-prevention diagnostics, and the design of treatments to avoid this serious side-effect in the future. This review examines the mechanisms behind the bone tissue damage that may produce the atypical fracture pattern observed increasingly with long-term bisphosphonate use. Our recent findings and those of others reviewed support that the mechanisms behind normal, healthy excavation and tunnel filling by bone remodeling units within cortical tissue strengthen mechanical integrity. The ability of cortical bone to resist the damage induced during cyclic loading may be altered by the reduced remodeling and increased tissue age resulting from long-term bisphosphonate treatment. Development of assessments for such potential fractures would restore confidence in pharmaceutical treatments that have the potential to spare millions in our aging population from the morbidity and death that often follow bone fracture.Peer reviewe
Detecting intestinal ischemia using near infrared spectroscopy
No full textBlood supply to the intestine can suddenly be interrupted. Acute mesenteric intestinal ischemia often requires invasive surgery to restore blood supply to the intestine. Early correction of vascular insufficiency is the most important factor in improving patient survival when confronted with acute mesenteric intestinal ischemia. A prolonged loss of blood flow results in irreversible damage to the intestine that can lead to death. It is also imperative that dead segments of the intestines be removed. Several subjective criteria are relied upon to differentiate viable from non-viable tissue, unfortunately, these criteria can lead to an inaccurate assessment. A porcine model of intestinal ischemia was used to determine the efficacy of using near infrared (NIR) spectroscopy to find ischemic segments of the intestine and detect the onset of reperfusion following resolution of vascular occlusion. Nine segments of intestine were identified and six were assigned to three treatment groups; (1) segments undergoing no vascular manipulations, (2) segments undergoing arterial/venous occlusion and (3) segments undergoing arterial/venous occlusion followed by reperfusion. The remaining segments were used as spacers and interposed between each of the ischemia segments. A classification model, using partial least square discriminant analysis, was built on the spectra collected from the segments with no vascular manipulations and the segments that were solely subjected to arterial/venous occlusion. The spectra collected from the intestinal segments that experienced both occlusion and reperfusion were used to test the classification model. The model was able to detect and distinguish ischemic intestinal tissue with a specificity and sensitivity exceeding 80% with an overall classification accuracy of 89%. The method appears to be well suited as an intra-operative assessment method when intestinal ischemia is a concern.Michael G. Sowa, Elicia Kohlenberg, Jeri R. Payette, Lorenzo Leonardi, Michelle A. Levasseur and Christopher B. Rile
Reader, Authors, and the Divine Author: An Evangelical Proposal for Identifying Paul\u27s OT Citations
No full textThe article discusses several approaches for the identification of Old Testament (OT) citations made by Paul. The author-centered approach of Stanley Porter allows the investigation of verbal and thematic parallelism between the Old and the New Testament, while the reader-centered approach of Christopher Stanley, Dietrich-Alex Koch and Richard Hay, considers the impact on the reader. It highlights the method of the Divine Author-centered approach which considers the context of the citation based on the book, the Bible and the canon
Archaeology of Trobriand knowledge: Foucault in the Trobriand Islands
No full textThis thesis holds that the application of the archaeological
method, developed by the French philosopher Michel
Foucault, to the field of anthropology reveals a hitherto
hidden primitive episteme. Such a project represents a
rejection of a search for a fundamental Truth, available
through the traditional figures of rationality, either
vertically in history or horizontally across cultures. The
form of reason posited by this project does not have a
constant and universal occurrence but is given in the discontinuous
figures of the episteme. The quest for a single
manifestation of the conditions of validity in reason is
replaced by a study of the conditions of possibility of the
truths, discourses and institutions of a primitive peoples.
The conditions of possibility for the emergence of the
elements of primitive knowledge and practices are available
through the application of the explanatory unities of the
archaeological method. These unities replace the traditional
explanatory role of the subject, with all of its psychological
baggage, which has a central role in modern theories of
rationality. The subject-knowledge link that dominates
traditional anthropological analyses is replaced by a powerknowledge
link that postulates the two axes of discursive
and non-discursive concerns. The discursive axis is concerned
with the objects, concepts, statements and discursive
formations of primitive knowledge while the non-discursive
axis is concerned with the systems of power that propagate
and sustain those discourses. These two axes constitute the
nature of the archaeology employed in this study.
This thesis is sustained by both negative and positive
evidence. The negative evidence takes the form of an antisubjectivist
thrust where the subject-dependent explanatory
unities of the tradition are replaced by the positivistic
elements of archaeology. The positive evidence primarily
takes the form of a detailed analysis of the presence of the
guiding codes of the episteme amongst the Trobriand Islanders
that give rise to their primitive knowledge and practices.
In this area, I make extensive use of Malinowski's
ethnographic observations for their breath of detail and
application without employing his subject-dependent psychobiological
conclusions. Further, I am proposing a transformative
position such that orality becomes a feature of the
episteme rather than its condition of possibility.
The guiding codes of the Trobriand episteme take the
form of enclosed oppositional figures that are everywhere
related to space. The Trobriand episteme provides the conditions
for the emergence of primitive discourses and orders
the experiences of the Trobrianders. The guiding figures of
the episteme are based in a form of complementary opposition,
causation as vitality and a dogma of topological space
that give rise to primitive knowledge which is a form of
divination. A significant part of this dissertation is taken
up with an examination of the detail and limitation of these
figures where ideas from Levy-Bruhl, Hallpike, and others
are employed to produce the most appropriate configuration
for my project. A particular form of language as the manipulation
of real signs, rather than ideational signs, has its
possibility in this configuration which has consequences for
the type of knowledge produced. The form of knowledge appropriate
to the presence of such a model of language is magic.
Writing has no possibility for emerging in this episteme
and, therefore, there are significant consequences for the
type of knowledge that can be maintained and propagated in a
context which must utilise static tradition to the detriment
of reflection.
An archaeological analysis of the Trobriand Islanders,
focusing on discourses on sex and marriage, the nature of
tabooed sexual acts, economic relations arising out of
marriage and the role of the polygamous chief, the nature of
love-magic and magic in general, reveals a shared possibility
for all of these discursive realms in the figures of the
episteme. These discourses are regulated by the presence of
a fundamental opposition between a brother and his sister.
This opposition forms the motif for primitive problematizations
and constitutes a vulnerable boundary which is the
appropriate focus of taboos relating to sex and food,
amongst others.
This primitive episteme characterises the unity of the
experiences of the Trobrianders. This experience is discontinuous
with our own and does not involve a role for the
individual ego. This project represents a worthwhile contribution
to an understanding of human experience and knowledge
in general which does not seek to reduce the natural diversity
of man to just the monotonous experience of modern man.
In conclusion, I tentatively speculate about the appropriateness
of the Trobriand figures for primitive experience in
general
Author correction: obesity and ethnicity alter gene expression in skin
No full textDaniel Butler was omitted from the author list in the original version of this Article. The Author contributions section now reads: “J.M.W. designed, conducted, and contributed to the writing of the manuscript, prepared Fig. 1. S.G. evaluated and did statistical analysis on the skin and fat samples, prepared Figs. 2–9. J.O.A. evaluated and contributed to writing the manuscript. D.B prepared and sequenced DNA libraries for the skin microbiota data, and wrote the applicable parts of the methods section. C.M. analyzed and wrote up the skin microbiota data, prepared Fig. 10. All authors have read the manuscript and approved its contents. D.D. analyzed and wrote up the skin microbiota data. S.Z. ran and analyzed the skin metabolite data. J.S. assisted in design, analysis and wrote up the skin metabolite data. J.K. assisted in analysis write up of skin and fat data. J.L.B. assisted in analysis, interpretation and writing of the manuscript. P.R.H. designed, analyzed, interpreted the data, and was the primary author of the manuscript.” This has been corrected in the PDF and HTML versions of the Article, and in the accompanying Supplementary Information file.</p
Examining Strategic Fit and Misfit in the Management of Knowledge Workers
No full textThis study advances research on strategic human resource management by examining the importance of alignment between an organization’s HR system and innovation strategy in achieving superior performance. We argue that alternative innovation strategies require different forms of knowledge behaviors from core knowledge workers to deal with the unique knowledge problems underlying exploration versus exploitation innovation strategies. Further, we argue that companies make distinct choices in terms of their HR strategies for managing core knowledge workers, and these alternative HR systems theoretically produce different employee ability, motivation, and opportunity outcomes which support different knowledge search and combination behaviors. We demonstrate, in a field study of 230 software firms, that alternative HR systems support either an exploration or exploitation strategy, and the alignment or misalignment between a firm’s HR system and strategy results in firm performance gains or penalties, respectively
Replication Data for: The Process of Revolutionary Protest: Development and Democracy in the Tunisian Revolution
No full textReplication data for the article "Replication Data for: The Process of Revolutionary Protest: Development and Democracy in the Tunisian Revolution." Note that raw Twitter is retrievable from the Dropbox link provided in the relevant R scripts. The download password will be provided by the author on request
ConstrictR and ConstrictPy: R Package and Python Tool for Microbiome Analysis
No full textabstract: I, Christopher Negrich, am the sole author of this paper, but the tools described were designed in collaboration with Andrew Hoetker. ConstrictR (constrictor) and ConstrictPy are an R package and python tool designed together. ConstrictPy implements the functions and methods defined in ConstrictR and applies data handling, data parsing, input/output (I/O), and a user interface to increase usability. ConstrictR implements a variety of common data analysis methods used for statistical and subnetwork analysis. The majority of these methods are inspired by Lionel Guidi's 2016 paper, Plankton networks driving carbon export in the oligotrophic ocean. Additional methods were added to expand functionality, usability, and applicability to different areas of data science. Both ConstrictR and ConstrictPy are currently publicly available and usable, however, they are both ongoing projects. ConstrictR is available at github.com/cnegrich and ConstrictPy is available at github.com/ahoetker. Currently, ConstrictR has implemented functions for descriptive statistics, correlation, covariance, rank, sparsity, and weighted correlation network analysis with clustering, centrality, profiling, error handling, and data parsing methods to be released soon. ConstrictPy has fully implemented and integrated the features in ConstrictR as well as created functions for I/O and conversion between pandas and R data frames with a full feature user interface to be released soon. Both ConstrictR and ConstrictPy are designed to work with minimal dependencies and maximum available information on the algorithms implemented. As a result, ConstrictR is only dependent on base R (v3.4.4) functions with no libraries imported. ConstrictPy is dependent upon only pandas, Rpy2, and ConstrictR. This was done to increase longevity and independence of these tools. Additionally, all mathematical information is documented alongside the code, increasing the available information on how these tools function. Although neither tool is in its final version, this paper documents the code, mathematics, and instructions for use, in addition to plans for future work, for of the current versions of ConstrictR (v0.0.1) and ConstrictPy (v0.0.1)
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