Delta Epsilon Research Articles

Different susceptibilities of the Antarctic and temperate copepods Tigriopus kingsejongensis and T. japonicus to ultraviolet (UV) radiation

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 561:99-107 (2016) - DOI: https://doi.org/10.3354/meps11946 Different susceptibilities of the Antarctic and temperate copepods Tigriopus kingsejongensis and T. japonicus to ultraviolet (UV) radiation Jeonghoon Han1, Jayesh Puthumana1, Min-Chul Lee1, Sanghee Kim2, Jae-Seong Lee1,* 1Department of Biological Science, College of Science, Sungkyunkwan University, Suwon 16419, South Korea 2Division of Life Sciences, Korea Polar Research Institute, Incheon 21990, South Korea *Corresponding author: jslee2@skku.edu ABSTRACT: To understand the effects of UV radiation on the Antarctic copepod Tigriopus kingsejongensis and the temperate copepod Tigriopus japonicus, the 96 h half lethal dose (LD50-96h) was calculated and compared with the levels of intracellular reactive oxygen species (ROS), antioxidant enzymatic activities, and gene expression profiles of the defensome in response to UV radiation over time (control, 1, 3, 6 h) in these copepods. ‘Defensome’ refers to the integrated system of defense mechanisms—such as detoxification, antioxidation, apoptosis, and cell proliferation—that were altered by UV exposure. The LD50-96h and no observed effect level (NOEL) at 96 h after UV exposure were determined as 23.16 kJ m-2 and 12 kJ m-2, respectively, in T. kingsejongensis and 26.42 kJ m-2 and 12 kJ m-2, respectively, in T. japonicus. ROS levels in response to 12 kJ m-2 UV increased slightly (p < 0.05) in T. kingsejongensis over time, and were also higher (p < 0.05) in T. japonicus. Transcript levels of antioxidant-related genes were mostly down-regulated in response to 12 kJ m-2 UV radiation, except for glutathione-S transferase delta epsilon (GST-Delta-E), manganese-superoxide dismutase (Mn-SOD), glutathione reductase (GR), and glutathione peroxidase (GPx) genes in T. kingsejongensis. T. japonicus heat shock protein (hsp) genes were mostly up-regulated, but only small hsp genes (hsp10 and hsp20) showed up-regulation in T. kingsejongensis. This finding provides a better understanding of how UV radiation affects in vivo endpoints and the relevant molecular response in 2 different copepod species from contrasting environments. KEY WORDS: Ultraviolet radiation · Antarctic copepod · Temperate copepod · Tigriopus kingsejongensis · Tigriopus japonicus · Reactive oxygen species Full text in pdf format Supplementary material PreviousNextCite this article as: Han J, Puthumana J, Lee MC, Kim S, Lee JS (2016) Different susceptibilities of the Antarctic and temperate copepods Tigriopus kingsejongensis and T. japonicus to ultraviolet (UV) radiation. Mar Ecol Prog Ser 561:99-107. https://doi.org/10.3354/meps11946 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 561. Online publication date: December 15, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

The Interplay Between Mathematicians’ Conceptual and Ideational Mathematics about Continuity of Complex-Valued Functions

Adopting Schiralli and Sinclair’s notions of conceptual mathematics (CM) and ideational mathematics (IM), we investigated mathematicians’ reasoning about continuity of complex-valued functions. While CM centers on formal mathematics as a discipline, IM focuses on how an individual perceives formal mathematics. There were four IM notions that the mathematicians used to convey the idea of continuity for complex-valued functions: control, topological features, preservation of closeness, and paths. The mathematicians’ IM tended to be grounded in their embodied experiences and espoused for pedagogical reasons, in preparation for other actions, or to assist their own reasoning. Some of the mathematicians’ IM metaphors conveyed a domain-first quality, which accounted for the domain of the function before mentioning any objects from the codomain. Given such metaphors did not capture the full structure of the epsilon-delta definition of continuity, the mathematicians transitioned to CM language in an effort to make their IM statements more rigorous. Our research suggests that while IM metaphors stemming from embodied experiences can serve as helpful tools for reasoning about continuity of complex-valued functions, one must be cognizant of ways in which the informal IM must be altered or extended to fully capture the CM. Given the pedagogical intent of many of the participants’ domain-first IM examples, we recommend that care be taken during instruction to deliberately elucidate where the IM is incomplete or fails to encapsulate the intricacies of the CM at hand.

Looking Back

The American Economist has a distinctive legacy in economics by being the official publication of the organization that honors academic excellence in the field, Omicron Delta Epsilon, The International Honor Society in Economics. This paper examines the history of The American Economist from its beginnings as a student-produced annual publication to a professionally produced academic journal with a global reach. During its more than 50-year run, the journal has published original works by many eminent economists, including 23 Nobel Prize winners. As one of the first journals that academic economists encounter, The American Economist continues to have a unique influence and impact on the economics profession.

Institutions and Economic Theory

Editor’s Introduction Originally published in Volume 36, Number 1, Spring 1992, pages 3-6. Omicron Delta Epsilon presented Douglass North (1920-2015) with the John R. Commons award in 1992 for his contributions to the economics profession. The following year he shared the Nobel Memorial Prize in Economic Sciences with Robert Fogel. The Nobel honored their work in applying economic theory and quantitative methods to the study of economic history and institutional change. As a pioneer in what has become known as cliometrics (named for the classical muse of history, Clio), Professor North’s scholarship focused on how human institutions and their organizational structures influence economic and societal outcomes. He is widely recognized as one of the founders of the New Institutional Economics school of thought. In this paper, his Commons Award lecture, Professor North describes and discusses his views on the limitations of neoclassical economics that are rooted in the assumption of instrumental rationality. His discourse on culturally influenced mental models and the limitations of our ability to process complex information presages the ongoing revolution in behavioral economics. This paper remains as timely today as it did when it first appeared in The American Economist.

Reflections On Economic Development

Editor’s Introduction Originally published in Volume 10, Number 1, Spring 1966, pages 5-13. Three years after the merger that created Omicron Delta Epsilon, Evsey Domar (1914-1997) became one of the first established “big names” to publish a paper in The American Economist. The occasion was precipitated by the inaugural delivery of the John R. Commons Lecture at the annual American Economic Association conference the previous December. ODE presents the Commons Award biennially to an outstanding economist in recognition of academic achievements and for service to the economics profession. The award memorializes Professor Commons who founded one of ODE’s predecessor honor societies in 1915 at the University of Wisconsin. Professor Domar, immortalized as one of the originators of the Harrod-Domar model of economic growth, was the first in a long and continuing line of prominent economists to receive the Commons Award, including Milton Friedman, Kenneth Arrow, Douglas North, Gary Becker, and Peter Diamond. In this paper, Professor Domar outlines his thoughts and ideas on why and how underdeveloped countries should institute market-oriented reforms to promote economic growth and prosperity. Fifty years later his words still ring true, “Economic development is a difficult and complex process, hard to deal with, because contrary to some of our favorite models, it is essentially not a capital but a human problem.”

The use of visual approach in teaching and learning the epsilon-delta definition of continuity

In this paper we introduce a new collaborative technique in teaching and learning the epsilon-delta definition of a continuous function at the point from its domain, which connects mathematical logic, combinatorics and calculus. This collaborative approach provides an opportunity for mathematical high school students to engage in mathematical inquiry outside of the classroom by completing exercises that are based on the idea of visualization. Thus, the proposed approach enables cultivation of mathematical creative thinking and helps students to build their mathematical knowledge about the concept of a continuous function.

Preparation of Liquid Crystal Doped with Nanomaterials and Studying of Electrical and Dielectric Properties

The effects of multiwall carbon nanotube on dielectric ansitropy and molecular reorientation properties of 4-hepty1-4'-cyanobiphenyl liquid crystal have been investigated. The 4-hepty1-4'-cyanobiphenyl liquid crystal exhibits the negative resitance effect at higher voltages (3.5 V), whereas rnultiwall carbon nanotube doped 4-hepty1-4'-cyanobiphenyl liquid crysatl shifts it to the lower voltages (0.3 V). The 4- hepty1-4'-cyanobiphenyl and multiwall carbon nanotube doped 4-hepty1-4'cyanobiphenyl liquid crystals indicate a p-type dielectric anisotropy behaviour. The multiwall carbon nanotube dopant increases the dielectric anisotropy Delta epsilon of 4-hepty1-4'-cyanobiphenyl as the dopant-used facilitates the reorientation of the molecules in liquid crystal. It is has shown that the negative resitance effect and molecular reorientation properties of the 4-hepty1-4'-cyanobiphenyl are changed with multiwall carbon nanotube dopant.

Rotational changes of the asteroid 99942 Apophis during the 2029 close encounter with Earth

Context. The close approach of the asteroid (99942) Apophis to Earth on April 13, 2029, at a distance of about 38 330 km, is naturally considered a dramatic and fascinating event by the astronomical community, as well as by the public. Aims. Although the orbital changes of the asteroid (due to the gravitational perturbations of our planet during the encounter) have been abundantly investigated, the simultaneous changes in the rotational characteristics of the asteroid have been poorly studied. Methods. In this paper, after numerically computing the perturbing rotational potential of Apophis due to Earth, we used a classical way of calculating variations in the precession psi and the obliquity epsilon, which enables us to determine the changes in position of the instantaneous pole of rotation in space during the encounter. By assigning a reasonable value of the unknown dynamical ellipticity of Apophis, deduced from a statistical study of a full sample of small asteroids, it follows that the changes in the precession Lambda psi and in the obliquity Delta epsilon of the asteroid during the 2029 encounter could be of a few degrees, which makes them an interesting challenge of detection by modern ground-based observations. Results. This study confirms the possible observability of the asteroid rotational change during a close approach. It should be updated and refined in the future, when orbital, physical, and rotational parameters of Apophis become more precise.

The History of Omicron Delta Epsilon: The International Honor Society in Economics

This year represents the 100th anniversary of the founding of the first economics honor society at the University of Wisconsin. This society, along with one founded at Harvard that same year merged in 1915 creating the National Order of Artus. In 1955, another economic honor society, Omicron Chi Epsilon, was founded at the City College of New York. In 1963, Artus and Omicron Chi Epsilon merged to become Omicron Delta Epsilon. This year also marks the 50th anniversary of the creation of Omicron Delta Epsilon. This is their story.

Using dynamic tools to develop an understanding of the fundamental ideas of calculus

Although dynamic geometry software has been extensively used for teaching calculus concepts, few studies have documented how these dynamic tools may be used for teaching the rigorous foundations of the calculus. In this paper, we describe lesson sequences utilizing dynamic tools for teaching the epsilon-delta definition of the limit and the fundamental theorem of calculus. The lessons were designed on the basis of observed student difficulties and the existing scholarly literature. We show how a combination of dynamic tools and guide questions allows students to construct their understanding of these calculus ideas.

Pensions, Taxes and The Budgetary Process

This lecture was delivered on the occasion of the John R. Commons Award presentation at the Allied Social Science Association meetings in Chicago, January 2012. Omicron Delta Epsilon presents the award biennially to an outstanding economist in recognition of achievements and service to both the economics profession and Omicron Delta Epsilon. The lecture represents part of the author's continuing exploration of the analysis and development of policies for Social Security and income taxation of earnings.

Which Mathematical Logic is the Logic of Mathematics?

The main tool of the arithmetization and logization of analysis in the history of nineteenth century mathematics was an informal logic of quantifiers in the guise of the “epsilon–delta” technique. Mathematicians slowly worked out the problems encountered in using it, but logicians from Frege on did not understand it let alone formalize it, and instead used an unnecessarily poor logic of quantifiers, viz. the traditional, first-order logic. This logic does not e.g. allow the definition and study of mathematicians’ uniformity concepts important in analysis. Mathematicians’ stronger logic was rediscovered around 1990 as the form of independence-friendly logic which hence is not a new logic nor a further development of ordinary first-order logic but a richer version of it.

Asymptotic behavior for a semilinear second order evolution equation

This paper is devoted to the qualitative analysis for a second order evolution equation u(tt) -Delta(u)-Delta u(t)-epsilon Delta u(tt)+f(u) = g(x) (epsilon is an element of [0, 1]) with critical nonlinearity. Some uniformly (w.r.t. epsilon is an element of [0,1]) asymptotic regularity about the solutions has been established for both g(x) is an element of L(2)(Omega) and g(x) is an element of H(-1), which shows that the solutions are exponentially approaching a more regular fixed subset uniformly (w.r.t. epsilon is an element of [0,1]). As an application of this regularity result, a family {epsilon(epsilon)}(epsilon is an element of[0,1]) of finite dimensional exponential attractors has been constructed. Moreover, to characterize the relation with a strongly damped wave equation (epsilon = 0), the upper semicontinuity, at epsilon = 0, of the global attractors has been proved.

Desmond Sylvester O'Doherty, MD, FAAN (1920–2010)

On August 6, 2010, the soul of Desmond Sylvester O'Doherty, MD, completed the longest battle of a life filled with enthusiasm and left this earth “to entertain our Lord in Heaven forever,” as an old Irish proverb declares. Desmond Sylvester O'Doherty, MD, FAAN. Born in the Republic of Ireland on July 27, 1920, he immigrated to the United States through Ellis Island with his mother, Mary Sweeney, and his brother, Sean, on May 2, 1922, becoming a citizen of the United States on April 29, 1930. Educated at LaSalle College and Jefferson Medical College in Philadelphia, he was elected to membership in several honorary societies, including Alpha Epsilon Delta, Sigma Chi , and Alpha Omega Alpha , receiving his MD …

Alan Brown and the Origins of Omicron Delta Epsilon—A Remembrance

Alan Brown and the Origins of Omicron Delta Epsilon—A Remembrance

Continuity analysis of programs

We present an analysis to automatically determine if a program represents a continuous function, or equivalently, if infinitesimal changes to its inputs can only cause infinitesimal changes to its outputs. The analysis can be used to verify the robustness of programs whose inputs can have small amounts of error and uncertainty---e.g., embedded controllers processing slightly unreliable sensor data, or handheld devices using slightly stale satellite data. Continuity is a fundamental notion in mathematics. However, it is difficult to apply continuity proofs from real analysis to functions that are coded as imperative programs, especially when they use diverse data types and features such as assignments, branches, and loops. We associate data types with metric spaces as opposed to just sets of values, and continuity of typed programs is phrased in terms of these spaces. Our analysis reduces questions about continuity to verification conditions that do not refer to infinitesimal changes and can be discharged using off-the-shelf SMT solvers. Challenges arise in proving continuity of programs with branches and loops, as a small perturbation in the value of a variable often leads to divergent control-flow that can lead to large changes in values of variables. Our proof rules identify appropriate ``synchronization points'' between executions and their perturbed counterparts, and establish that values of certain variables converge back to the original results in spite of temporary divergence. We prove our analysis sound with respect to the traditional epsilon-delta definition of continuity. We demonstrate the precision of our analysis by applying it to a range of classic algorithms, including algorithms for array sorting, shortest paths in graphs, minimum spanning trees, and combinatorial optimization. A prototype implementation based on the Z3 SMT-solver is also presented.

Abstract B264: IC261 induces cell cycle arrest and apoptosis of human cancer cells via a CK1δ/ε independent mechanism

Abstract Casein kinase 1 delta (CK1δ) and CK1 epsilon (CK1ε) regulate Wnt/β catenin signaling and their dysregulation has been implicated in a variety of human cancers. Kinome RNAi screens and as well as targeted studies have identified CK1δ and CK1ε as prosurvival factors in a variety of cancer cell lines. While RNAi knockdown of CK1δ or CK1ε displayed only modest growth inhibition of various cell lines, the CKIδ/ε selective inhibitor 3-[2,4,6-(trimethoxyphenyl) methylidenyl]-indolin-2-one (IC261)(with an IC50 in the 20–50 µM range) has proven even more effective at selective killing of cancer cells, even at submicromolar levels. This finding has been taken as supportive evidence for the role of CKIε and CKIδ in cancer. The recent development of a selective and nanomolar CKIδ/ε inhibitor, PF670462, affords an opportunity to further explore this hypothesis. We found that PF670462 effectively blocked CK1 kinase activity and suppressed Wnt/β-catenin signaling in both HEK293 cells and HT1080 fibrosarcoma cells at submicromolar concentrations. However, consistent with the results of siRNA knockdown of CK1ε, PF670462 failed to induce cancer cell death at these concentrations. In contrast, we found that while 100 nM IC261 did not inhibit of CK1ε activity nor block Wnt/ catenin signaling in vivo, it resulted in the rapid induction of G2/M arrest of cell cycle and apoptosis in human cancer, but not non-transformed, cells. Taken together, inactivation of CK1δ/ε and subsequent block of Wnt/β catenin signaling may not be sufficient to inhibit cancer cell survival. Furthermore, IC261 potently regulates additional cancer cell targets at concentrations much lower than that required for CK1 inhibition and these novel unknown targets appear to be important for the maintenance of human cancer cell survival. Identification of the IC261 targets may provide insights into the mechanism of selective cancer cell toxicity. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):B264.

The αβ T Cell Receptor Is an Anisotropic Mechanosensor

Thymus-derived lymphocytes protect mammalian hosts against virus- or cancer-related cellular alterations through immune surveillance, eliminating diseased cells. In this process, T cell receptors (TCRs) mediate both recognition and T cell activation via their dimeric alphabeta, CD3 epsilon gamma, CD3 epsilon delta, and CD3 zeta zeta subunits using an unknown structural mechanism. Here, site-specific binding topology of anti-CD3 monoclonal antibodies (mAbs) and dynamic TCR quaternary change provide key clues. Agonist mAbs footprint to the membrane distal CD3 epsilon lobe that they approach diagonally, adjacent to the lever-like C beta FG loop that facilitates antigen (pMHC)-triggered activation. In contrast, a non-agonist mAb binds to the cleft between CD3 epsilon and CD3 gamma in a perpendicular mode and is stimulatory only subsequent to an external tangential but not a normal force ( approximately 50 piconewtons) applied via optical tweezers. Specific pMHC but not irrelevant pMHC activates a T cell upon application of a similar force. These findings suggest that the TCR is an anisotropic mechanosensor, converting mechanical energy into a biochemical signal upon specific pMHC ligation during immune surveillance. Activating anti-CD3 mAbs mimic this force via their intrinsic binding mode. A common TCR quaternary change rather than conformational alterations can better facilitate structural signal initiation, given the vast array of TCRs and their specific pMHC ligands.

In vitro preparation and characterization of the human CD3εε homodimer and CD3εγ and CD3εδ heterodimers

The CD3 molecule is a critical component of both humoral and cellular immune responses, and yet while the structure and molecular assembly of other key mediators such as CD4 and CD8 have been reported, individual CD3 subunits have not been well characterized. Our understanding of the manner in which they interact remains limited, and the question of how many subunits are required for a functional CD3 molecular complex is yet to be addressed. It has been suggested that CD3 epsilon pairs with CD3 gamma or with CD3 delta, forming CD3 epsilon gamma and CD3 epsilon delta heterodimers that associate with alpha/beta T cell receptors (TCRs) and CD3 zeta 2 dimers. In this study we investigated whether interactions between each CD3 epsilon subunit play a role in the formation of the CD3 molecular complex. Our results revealed that the human CD3 epsilon subunit forms a homodimer structure, which is a crucial piece of information for the elucidation of cellular signaling following TCR receptor ligation, and provide insight into our understanding of the molecular assembly of the CD3 molecular complex.

Semiclassical stationary states for nonlinear Schrödinger equations with fast decaying potentials

We study the existence of positive solutions for a class of nonlinear Schrodinger equations of the type -epsilon(2)Delta u + Vu = u(p) in R-N, where N >= 3, p > 1 is subcritical and V is a nonnegative continuous potential. Amongst other results, we prove that if V has a positive local minimum, and N/N-2 0 around the local minimum point of V. The novelty is that no restriction is imposed on the rate of decay of V. In particular, we cover the case where V is compactly supported.