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Search Results: 1 - 10 of 330184 matches for " Jeffrey S. Buyer "
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Understanding and Enhancing Soil Biological Health: The Solution for Reversing Soil Degradation
R. Michael Lehman,Cynthia A. Cambardella,Diane E. Stott,Veronica Acosta-Martinez,Daniel K. Manter,Jeffrey S. Buyer,Jude E. Maul,Jeffrey L. Smith,Harold P. Collins,Jonathan J. Halvorson,Robert J. Kremer,Jonathan G. Lundgren,Tom F. Ducey,Virginia L. Jin,Douglas L. Karlen
Sustainability , 2015, DOI: 10.3390/su7010988
Abstract: Our objective is to provide an optimistic strategy for reversing soil degradation by increasing public and private research efforts to understand the role of soil biology, particularly microbiology, on the health of our world’s soils. We begin by defining soil quality/soil health (which we consider to be interchangeable terms), characterizing healthy soil resources, and relating the significance of soil health to agroecosystems and their functions. We examine how soil biology influences soil health and how biological properties and processes contribute to sustainability of agriculture and ecosystem services. We continue by examining what can be done to manipulate soil biology to: (i) increase nutrient availability for production of high yielding, high quality crops; (ii) protect crops from pests, pathogens, weeds; and (iii) manage other factors limiting production, provision of ecosystem services, and resilience to stresses like droughts. Next we look to the future by asking what needs to be known about soil biology that is not currently recognized or fully understood and how these needs could be addressed using emerging research tools. We conclude, based on our perceptions of how new knowledge regarding soil biology will help make agriculture more sustainable and productive, by recommending research emphases that should receive first priority through enhanced public and private research in order to reverse the trajectory toward global soil degradation.
Diffusive Decay of the Environment Viewed by the Particle
Paul de Buyer,Jean-Christophe Mourrat
Mathematics , 2014,
Abstract: We prove an optimal diffusive decay of the environment viewed by the particle in random walk among random independent conductances, with, as a main assumption, finite second moment of the conductance. Our proof, using the analytic approach of Gloria, Neukamm and Otto, is very short and elementary.
An analysis of NK and generalized NK landscapes
Jeffrey S. Buzas,Jeffrey Dinitz
Computer Science , 2013,
Abstract: Simulated landscapes have been used for decades to evaluate search strategies whose goal is to find the landscape location with maximum fitness. Applications include modeling the capacity of enzymes to catalyze reactions and the clinical effectiveness of medical treatments. Understanding properties of landscapes is important for understanding search difficulty. This paper presents a novel and transparent characterization of NK landscapes. We prove that NK landscapes can be represented by parametric linear interaction models where model coefficients have meaningful interpretations. We derive the statistical properties of the model coefficients, providing insight into how the NK algorithm parses importance to main effects and interactions. An important insight derived from the linear model representation is that the rank of the linear model defined by the NK algorithm is correlated with the number of local optima, a strong determinant of landscape complexity and search difficulty. We show that the maximal rank for an NK landscape is achieved through epistatic interactions that form partially balanced incomplete block designs. Finally, an analytic expression representing the expected number of local optima on the landscape is derived, providing a way to quickly compute the expected number of local optima for very large landscapes.
Green Tea Polyphenols Mediated Apoptosis in Intestinal Epithelial Cells by a Fadd-Dependent Pathway  [PDF]
Helieh S. Oz, Jeffrey L. Ebersole
Journal of Cancer Therapy (JCT) , 2010, DOI: 10.4236/jct.2010.13018
Abstract: Colorectal cancer is the most common malignant complication in patients with chronic inflammatory bowel disease (IBD). In addition, these patients are at risk for developing painful complications during chemotherapy due to cytotoxic effects of drugs currently in use. Past studies have suggested a protective effect of tea consumption on gastrointestinal (GI) malignancies. Green tea polyphenols (GrTP) inhibited carcinogen-induced GI tumors in rodents and induced apoptosis in various carcinoma cell lines. We hypothesized that GrTP and its polyphenolic compounds regulate apoptosis in the intestinal epithelia. In this study, the effects of GrTP and its polyphenolics on apoptosis was evaluated in intestinal epithelial, IEC-6, cells grown to 85% confluency. GrTP (400-800 mg/ml) induced DNA fragmentation in a dose dependent fashion. Higher concentrations (> 800 mg/ml) induced a mixed apoptosis and cytolysis. Epithelial cells exposed to GrTP and a major polyphenol, EGCG, but not EGC or EC, increased caspase activities in a time and dose dependent manner. The caspase inhibitors rescued cells from GrTP and EGCG-induced cell death. Concomitantly, GrTP resulted in activation of fatty acid synthase (Fas)-associated protein with death domain (FADD) and recruitment to Fas/CD95 domain 30 minutes following treatment. While GrTP also blocked NF-?B activation, an NF-?B inhibitor (MG132) only promoted cytolysis. In conclusion, these data demonstrated GrTP and EGCG induced apoptosis in intestinal epithelia mediated by caspase-8 through a FADD dependent pathway. Future investigation may warrant preventive as well as therapeutic strategies for GrTP in GI malignancy.
Do Credit Rating Agencies Sacrifice Timeliness by Pursuing Rating Stability? Evidence from Equity Market Reactions to CreditWatch Events  [PDF]
Jenny Gu, Jeffrey S. Jones, Pu Liu
Theoretical Economics Letters (TEL) , 2014, DOI: 10.4236/tel.2014.45042
Abstract:

In this paper we examine how well CreditWatch is used by credit rating agencies to balance two conflicting goals: rating timeliness and rating stability. Examining equity market reactions around CreditWatch events in 2002-2005, we find evidence that while CreditWatch has improved rating timeliness, its intended purpose has not been completely achieved. Equity prices start to change days before companies are listed on CreditWatch and abnormal equity returns of firms prior to being listed on CreditWatch are effective predictors of the ultimate change in ratings. The findings in the study suggest that in the pursuit of rating stability, rating agencies may have sacrificed rating timeliness.

Black Sun: Ocular Invisibility of Relativistic Luminous Astrophysical Bodies  [PDF]
Jeffrey S. Lee, Gerald B. Cleaver
Journal of High Energy Physics, Gravitation and Cosmology (JHEPGC) , 2016, DOI: 10.4236/jhepgc.2016.24048
Abstract: Considered as a gedanken experiment are the conditions under which the relativistic Doppler shifting of visible electromagnetic radiation to beyond the human ocular range could reduce the incident radiance of the source, and render a luminous astrophysical body (LAB) invisible to a naked eye. This paper determines the proper distance as a function of relativistic velocity at which a luminous object attains ocular invisibility.
Atrial Fibrillation Induction in a Pediatric Patient during Adenosine Administration  [PDF]
Jeffrey A. Robinson, Christopher S. Snyder
World Journal of Cardiovascular Diseases (WJCD) , 2017, DOI: 10.4236/wjcd.2017.73006
Abstract:
Adenosine by rapid intravenous bolus is frequently utilized in clinical practice as both a pharmacologic treatment for supraventricular (reentrant) tachycardia and in provocative testing for the diagnosis of Wolff-Parkinson-White (WPW) syndrome. This is a case report of an otherwise healthy adolescent female who received adenosine during a provocative test for WPW syndrome. Immediately after receiving adenosine, the patient had a self-limited episode of atrial fibrillation. When administering adenosine, teams should be aware of the potential adverse effects and be prepared to treat appropriately.
The Fuzzy Logic Method for Simpler Forecasting
Jeffrey E. Jarrett,Jeffrey S. Plouffe
International Journal of Engineering Business Management , 2011,
Abstract: Fildes and Makridakis (1998), Makridakis and Hibon (2000), and Fildes (2001) indicate that simple extrapolative forecasting methods that are robust forecast equally as well or better than more complicated methods, i.e. Box-Jenkins and other methods. We study the Direct Set Assignment (DSA) extrapolative forecasting method. The DSA method is a non-linear extrapolative forecasting method developed within the Mamdani Development Framework, and designed to mimic the architecture of a fuzzy logic control system. We combine the DSA method Winters' Exponential smoothing. This combination provides the best observed forecast accuracy in seven of nine subcategories of time series, and is the top three in terms of observed accuracy in two subcategories. Hence, fuzzy logic which is the basis of the DSA method often is the best method for forecasting.
Raphides in the Uncalcified Siphonous Green Seaweed, Codium minus (Schmidt) P. C. Silva
Jeffrey S. Prince
Journal of Marine Biology , 2012, DOI: 10.1155/2012/382498
Abstract: The vacuole of utricles, the outermost cell layer of the siphonous green seaweed, Codium minus, had numerous single needles and needle bundles. The crystals composing each needle appeared arranged in a twisted configuration, both ends were pointed, and each needle was contained in a matrix or membrane; bundles of needles appeared enclosed by a matrix. Chemical and electron diffraction analysis indicated that the needles consisted of calcium oxalate. This is the first paper on terrestrial plant-like raphides in an alga. 1. Introduction Bundles of acicular crystals of calcium oxalate formed in specialized cells, idioblasts, are termed raphides in embryophytes [1–3]. Only one bundle of needles occurs per idioblast; the needles are long; needle length from several key pacific economic plants had a mean minimum length of 43?μm [4]. Each needle in a bundle is enclosed in a membrane, the crystal chamber [5–7], and bundles are enclosed by a water-soluble organic matrix, termed the vacuolar matrix [5, 8]. Raphides can burst through mature idioblasts due to swelling of the large amounts of mucilage contained in the cell [9]. Single needles do not occur in terrestrial plants but only as a bundle of needles [9, 10]. Individual needles, raphide, are found as microfossils in soils [4]. Abundant evidence supports the role of these needles in deterring vertebrate and invertebrate herbivory [1, 3, 7, 11, 12]. Raphides abrade the mouth and digestive tract of terrestrial herbivores causing edema; in addition, grooves in the needles may inject noxious plant metabolites and bacteria into these grazers [2]. Defense against herbivory in the marine environment generally involves calcification of the outer surface of green, red, and brown seaweeds [13]. This hard outer surface of calcium carbonate not only increases the difficulty of getting to the soft inner tissue, but consumption of the hard outer matrix can also alter the digestive pH, a deterrent for several herbivores [1, 13]. No alga has been found to have raphides. Where needles (acicular crystals) have been found, they appear singly, not in bundles of needles; they are surrounded by a vacuolar membrane or crystal chamber but not both, are generally very small, or reside individually in the cytoplasm and not the cell vacuole [14–18]. Single needles also occur in the cell vacuole of both lightly calcified parts of otherwise heavily calcified seaweeds [19–21]. We provide the first report of calcium oxalate crystals with all the characteristics that typify raphides of terrestrial plants. Large numbers of single needles and
Non-long terminal repeat (non-LTR) retrotransposons: mechanisms, recent developments, and unanswered questions
Jeffrey S Han
Mobile DNA , 2010, DOI: 10.1186/1759-8753-1-15
Abstract: The biological drive to replicate makes it almost inevitable that selfish genetic elements will populate genomes [1]. Indeed, genome sequencing has revealed that single copy genes are often vastly outnumbered by repetitive transposable elements [2-6]. The abundance and distribution of any particular transposon depends on how aggressive the transposon is (how quickly it can multiply in copy number), where the transposon inserts new copies, and how the host responds. Since these factors can vary greatly, the transposon content of each species is unique and virtually impossible to predict a priori. In humans, this number is at least 45% [2].Transposons can be divided into two broad classes: DNA transposons and retrotransposons. DNA transposons replicate via a cut and paste mechanism [7], whereas retrotransposons replicate using an RNA intermediate. Retrotransposons can be further subdivided into long terminal repeat (LTR) and non-LTR retrotransposons. LTR retrotransposons are retroviral-like in structure and mechanism [8]. Non-LTR retrotransposons (also called LINEs, polyA retrotransposons, or target-primed (TP) retrotransposons), as implied by their name, do not contain LTRs and instead take on the likeness of an integrated mRNA. They are ancient genetic elements that have persisted in eukaryotic genomes for hundreds of millions of years [9], and are perhaps best known for their enormous success multiplying in the human genome. Although non-LTR retrotransposons can be parasitized by non-autonomous elements (for example, short interspersed transposable elements (SINEs)), this review will focus on autonomous elements, which encode the protein machinery necessary for their self-mobilization.Full length, autonomous non-LTR retrotransposons typically contain one or two open reading frames (ORFs). The general structure of three model examples, the Bombyx mori R2 element, the human L1 element, and the Drosophila melanogaster I factor, are depicted in Figure 1. Central to ret
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