Unification of Type II Strings and T-duality

We present a unified description of the low-energy limits of type II string theories. This is achieved by a formulation that doubles the space-time coordinates in order to realize the T-duality group O(10,10) geometrically. The Ramond-Ramond fields are described by a spinor of O(10,10), which couples to the gravitational fields via the Spin(10,10) representative of the so-called generalized metric. This theory, which is supplemented by a T-duality covariant self-duality constraint, unifies the type II theories in that each of them is obtained for a particular subspace of the doubled space.Comment: 4 pages, v2: minor changes, to appear in PR

Topics in double field theory

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 199-204).The existence of momentum and winding modes of closed string on a torus leads to a natural idea that the field theoretical approach of string theory should involve winding type coordinates as well as the usual space-time coordinates. Recently developed double field theory is motivated from this idea and it implements T-duality manifestly by doubling the coordinates. In this thesis we will mainly focus on the double field theory formulation of different string theories in its low energy limit: bosonic, heterotic, type II and its massive extensions, and M = 1 super-gravity theory. In chapter 2 of the thesis we study the equivalence of different formulations of double field theory. There are three different formulations of double field theory: background field E formulation, generalized metric H formulation, and frame field EAM formulation. Starting from the frame field formalism and choosing an appropriate gauge, the equivalence of the three formulations of bosonic theory are explicitly verified. In chapter 3 we construct the double field theory formulation of heterotic strings. The global symmetry enlarges to O(D, D + n) for heterotic strings and the enlarged generalized metric features this symmetry. The structural form of bosonic theory can directly be applied to the heterotic theory with the enlarged generalized metric. In chapter 4 we develop a unified framework of double field theory for type II theories. The Ramond-Ramond potentials fit into spinor representations of the duality group 0(D, D) and the theory displays Spin+(D, D) symmetry with its self-duality relation. For a specific form of RR 1-form the theory reduces to the massive deformation of type IIA theory due to Romans. In chapter 5 we formulate the K = 1 supersymmetric extension of double field theory including the coupling to n abelian vector multiplets. This theory features a local 0(1, 9 + n) x 0(1, 9) tangent space symmetry under which the fermions transform.by Seung Ki Kwak.Ph.D

Institutional theory of naive money

Thesis: Ph. D., Massachusetts Institute of Technology, Sloan School of Management, 2018.Cataloged from PDF version of thesis.Includes bibliographical references.In the first chapter, I propose a theoretical framework to elucidate how capital from unsophisticated investors (naive money) is associated with fund performance dynamics. In the framework, when naive money invested in a fund exceeds the ideal amount for the manager's skill, it leads funds to under-perform persistently. In contrast, the model predicts that, when the amount of invested naive money is smaller than the ideal size of a fund reflecting the manager's skill, the fund performs the same as the market on a risk-adjusted basis. Empirical results using mutual fund data support this prediction. In the second chapter, I develop a model that characterizes how naive money influences the decisions of active mutual fund managers: in particular, managerial effort, fees, marketing expenses, private benefit-seeking, and risk-taking. My model predicts that managers who receive a surplus of naive money are inclined to reduce their managerial effort, charge higher fees, allocate more resources towards marketing, and pursue their private benefit by sacrificing returns to investors. In addition, it also predicts that a manager is most likely to increase idiosyncratic risk when the amount of invested naive money gets closer to a certain size of the fund that reflects the manager's skill. In the third chapter, I build a model to study how naive money affects funds' survivorship and entry decisions. Sufficient capital provision from unsophisticated investors elongates the survival of unskilled managers. Competition among funds determines the industry equilibrium, and the equilibrium is affected by several key market conditions: the aggregate investment opportunities, the aggregate capital inflows from unsophisticated investors, and the supply of skilled managers. When AM markets are heterogeneous in investor sophistication, the model shows, AM markets with more sophisticated investors (say, hedge fund markets) differentiate from those with less sophisticated investors (say, mutual fund markets). Skilled managers generate more value in hedge fund markets, and choose to enter those markets.by Seung Ki Kwak.1. Theory and Evidence: Mutual Fund Performance Dynamics -- 2. IO of Active Mutual Funds -- 3. IO of the Active AM Industry: Entries and Exits.Ph. D

Differentially Private Multivariate Statistics with an Application to Contingency Table Analysis

Differential privacy (DP) has become a rigorous central concept in privacy protection for the past decade. Among various notions of DP, $f$-DP is an easily interpretable and informative concept that tightly captures privacy level by comparing trade-off functions obtained from the hypothetical test of how well the mechanism recognizes individual information in the dataset. We adopt the Gaussian differential privacy (GDP), a canonical parametric family of $f$-DP. The Gaussian mechanism is a natural and fundamental mechanism that tightly achieves GDP. However, the ordinary multivariate Gaussian mechanism is not optimal with respect to statistical utility. To improve the utility, we develop the rank-deficient and James-Stein Gaussian mechanisms for releasing private multivariate statistics based on the geometry of multivariate Gaussian distribution. We show that our proposals satisfy GDP and dominate the ordinary Gaussian mechanism with respect to $L_2$-cost. We also show that the Laplace mechanism, a prime mechanism in $\varepsilon$-DP framework, is sub-optimal than Gaussian-type mechanisms under the framework of GDP. For a fair comparison, we calibrate the Laplace mechanism to the global sensitivity of the statistic with the exact approach to the trade-off function. We also develop the optimal parameter for the Laplace mechanism when applied to contingency tables. Indeed, we show that the Gaussian-type mechanisms dominate the Laplace mechanism in contingency table analysis. In addition, we apply our findings to propose differentially private $\chi^2$-tests on contingency tables. Numerical results demonstrate that differentially private parametric bootstrap tests control the type I error rates and show higher power than other natural competitors

The Clinical Evaluation between Overtraining Syndrome and Exercise-related Immunity

The present study was performed to analyze and review the physical and immune responses to overtraining syndrome in humans. Overreaching refers to the initial phage of overtraining syndrome and has been known as a physical fatigue which is mainly from metabolic imbalance. It has been known that overtraining also results in a loss of adaptability which may lead to an attenuation of exercise performance, sleeping disorder, central fatigue, neurohormonal changes, difficulty recovery to physical stress, and immunological changes. Additionally, overtraining syndrome is characterized by persistent fatigue, poor performance in sport due to the prolonged and strenuous physical training. Also, previous studies reported that endurance athletes experienced a high incidence of URTI during intense training and the post training. And also, high-performance athletes reported that suppression of cell mediated and anti-body mediated immune function. NK cell numbers were also reduced in the period of overtraining syndrome. Major components of prevention and treatment for the overtraining syndrome are screening, education, and detraining. Furthermore, the combination of these prevention and treatment strategies will be much helpful. Therefore, the current review will be helpful for athletes and individuals who are at the risk of overtraining syndrome

How to tell a constructivist science teacher: An interview protocol to diagnose a constructivist teacher

2001As a research paradigm, constructivism offers accounts of the epistemology of science, inspires science education curriculum reform programs, underpins major research programs in science education, and is also the foundation of many science-teacher training programs where constructivist teaching methods are widely advocated. Underlying all versions of constructivism are the philosophical constructs of epistemological commitments and ontological beliefs. Specifically, educational constructivism can be divided into individual, radical, and social constructivism depending on the unique ontological, epistemological, and pedagogical commitments for each version. In this article, we present an interview protocol with which researchers can elicit the philosophical foundations (i.e., ontological beliefs and epistemological commitments) that preservice teachers gave to support of their developing notions of several versions of educational constructivism through in-depth interviews. By providing researchers and educators with our interview protocol and methods, we intend to show one way of revealing an individuals often implicitly held philosophical beliefs and commitments. For each ontological and epistemological beliefs subcategory, a detailed definition along with two to three exemplary quotes taken from the interview transcripts from a previous research is also provided. The development of a system of categories for identifying constructivist ideas (i.e., ontological, epistemological, and pedagogical profiles), and its use in tracing of the development of preservice teachers beliefs changes throughout their university coursework, has the potential to contribute to a better understanding of how preservice teachers learn to teach. Accordingly, this interview protocol will be a valuable theoretical and analytical framework in describing the relationship between a teachers beliefs about nature of knowledge (or reality) and his or her conceptions of science teaching and learning. This understanding can lead to a restructuring of the science teacher education program's methods courses

Changes in Proopiomelanocortin Primary Transcript Levels in the Anterior Pituitary Accompany Increased Adrenocorticotropin Secretion During the Diurnal Surge

Proopiomelanocortin (POMC) gene transcription in the anterior pituitary varies during stress and glucocorticoid feedback. These changes appear to parallel alterations in peptide release. The diurnal rhythm of the hypothalamo-pituitary-adrenal axis also involves the periodic excursion of adrenocorticotropin (ACTH) levels in plasma, but it is not clear whether the diurnal release is accompanied by changes at the transcriptional level. In the present study, we have initially characterized the heteronuclear species of POMC (hnPOMC) RNA found in the anterior pituitary by a Northern blot analysis and subsequently used this method to quantitate relative changes in the levels of heteronuclear transcript during diurnal stimulation. Two species of RNA migrating at 6.0 kb and 4.1 kb were found in the nuclear fraction of the anterior pituitary. Successive probing by various POMC cRNAs indicated that the 6.0 kb fragment was the primary transcript and the 4.1 kb fragment corresponded to the intron A-containing processing intermediate of POMC. The nuclear species were quantitated after acute swim stress and during the diurnal ACTH secretion. Acute swim increased plasma ACTH levels by 243% after 30 min. This was paralleled by a 214% increase in the primary transcript RNA levels. Endogenous circadian stimulation in the evening produced a smaller rise of plasma ACTH (79%), and was accompanied by a 34% increase in POMC hnRNA levels. Nuclear processing intermediate (4.1 kb) and the mRNA levels did not vary during the evening. These results suggest that the diurnal mechanism transiently increases ACTH release as well as POMC gene transcription in the anterior pituitary. Release and transcription appear to be tightly coupled during circadian activation as well as during stress.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75121/1/j.1365-2826.1992.tb00340.x.pd

hVH-5: A Protein Tyrosine Phosphatase Abundant in Brain that Inactivates Mitogen-Activated Protein Kinase

A novel protein tyrosine phosphatase [ h omologue of v accinia virus H 1 phosphatase gene clone 5 (hVH-5)] was cloned; it shared sequence similarity with a subset of protein tyrosine phosphatases that regulate mitogen-activated protein kinase. The catalytic region of hVH-5 was expressed as a fusion protein and was shown to hydrolyze p -nitrophenylphosphate and inactivate mitogen-activated protein kinase, thus proving that hVH-5 possessed phosphatase activity. A unique proline-rich region distinguished hVH-5 from other closely related protein tyrosine phosphatases. Another feature that distinguished hVH-5 from related phosphatases was that hVH-5 was expressed predominantly in the adult brain, heart, and skeletal muscle. In addition, in situ hybridization histochemistry of mouse embryo revealed high levels of expression and a wide distribution in the central and peripheral nervous system. Some specific areas of abundant hVH-5 expression included the olfactory bulb, retina, layers of the cerebral cortex, and cranial and spinal ganglia. hVH-5 was induced in PC12 cells upon nerve growth factor and insulin treatment in a manner characteristic of an immediate-early gene, suggesting a possible role in the signal transduction cascade.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65883/1/j.1471-4159.1995.65041823.x.pd

Invariances and Equations of Motion in Double Field Theory

We investigate the full set of equations of motion in double field theory and discuss their O(D,D) symmetry and gauge transformation properties. We obtain a Ricci-like tensor, its associated Bianchi identities, and relate our results to those with a generalized metric formulation.Comment: 24 page