116 research outputs found
Marginal sea overflows and the upper ocean interaction
Get PDFAuthor Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 387-403, doi:10.1175/2008JPO3934.1.Marginal sea overflows and the overlying upper ocean are coupled in the vertical by two distinct mechanisms—by an interfacial mass flux from the upper ocean to the overflow layer that accompanies entrainment and by a divergent eddy flux associated with baroclinic instability. Because both mechanisms tend to be localized in space, the resulting upper ocean circulation can be characterized as a β plume for which the relevant background potential vorticity is set by the slope of the topography, that is, a topographic β plume.
The entrainment-driven topographic β plume consists of a single gyre that is aligned along isobaths. The circulation is cyclonic within the upper ocean (water columns are stretched). The transport within one branch of the topographic β plume may exceed the entrainment flux by a factor of 2 or more.
Overflows are likely to be baroclinically unstable, especially near the strait. This creates eddy variability in both the upper ocean and overflow layers and a flux of momentum and energy in the vertical. In the time mean, the eddies accompanying baroclinic instability set up a double-gyre circulation in the upper ocean, an eddy-driven topographic β plume. In regions where baroclinic instability is growing, the momentum flux from the overflow into the upper ocean acts as a drag on the overflow and causes the overflow to descend the slope at a steeper angle than what would arise from bottom friction alone.
Numerical model experiments suggest that the Faroe Bank Channel overflow should be the most prominent example of an eddy-driven topographic β plume and that the resulting upper-layer transport should be comparable to that of the overflow. The overflow-layer eddies that accompany baroclinic instability are analogous to those observed in moored array data. In contrast, the upper layer of the Mediterranean overflow is likely to be dominated more by an entrainment-driven topographic β plume. The difference arises because entrainment occurs at a much shallower location for the Mediterranean case and the background potential vorticity gradient of the upper ocean is much larger.SK’s support during the time of his Ph.D.
research in the MIT/WHOI Joint Program was provided
by the National Science Foundation through
Grant OCE04-24741. JP and JY have also received
support from the Climate Process Team on Gravity
Current Entrainment, NSF Grant OCE-0611530. JY has
also been supported by NSF Grant OCE-0351055
Overflows and upper ocean interactions : a mechanism for the Azores current
Get PDFThesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2006.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 155-162).The oceanic response to overflows is explored using a two-layer isopycnal model. Overflows are a major source of the dense water of the global deep ocean, originating from only a few marginal seas. They enter the open ocean as dense gravity currents down a continental slope and play a crucial role in the deep ocean circulation. To understand the dynamics of these overflows, previous studies simplified their dynamics by treating the overlying ocean as inactive. This simplification may be a first approximation for the overflow but not for the overlying ocean. The Mediterranean overflow, for example, entrains about 2 Sv of overlying Atlantic water when it enters the Atlantic through Gibraltar Strait. The upper ocean must balance the mass loss and vortex stretching associated with entrainment. Thus for the upper ocean, overflows represent a localized region of intense mass and PV forcing. The simulations in this study show that in the upper layer, entrainment forces a cyclonic circulation along bathymetric contours. This is a topographic [beta]-plume and its transport depends on the entrainment region size and the topographic slope.(cont.) Baroclinic instability also develops and creates eddy thickness flux to the in-shore direction, forcing a double gyre topographic [beta]-plume near the strait due to eddy PV flux convergence on the in-shore side of the continental slope and divergence on the offshore side. When the upper oceanic response to overflows is examined specifically for the Mediterranean overflow, the upper ocean is found to establish two trans-Atlantic zonal jets, analogous to the Azores current and the Azores Counter current. These two zonal jets are an extension of the topographic [beta]-plume driven by the overflow. Because the eddies in the steep slope region near Cape St. Vincent drive a mean flow across the slope, the topographic [beta]-plume connects to the Atlantic Ocean to become a basin scale flow. This thesis shows that overflows can induce a significant circulation in the upper ocean, and for the Mediterranean overflow, this circulation is a basin scale flow.by Shinichiro Kida.Ph.D
Intonation and interface conditions
Get PDFThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2003.Includes bibliographical references (p. 179-184).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.The thesis presents a theoretical and experimental investigation of the interaction between focus intonation pattern (FIP) and certain syntactic phenomena-especially those involving wh-questions-in Japanese. A phonological mechanism of FIP formation is proposed that accounts for the variety of FIPs observed in various syntactic configurations. In the FIPs of Japanese wh-questions, the F0 of wh-phrases is raised, and the F0 of following phrases is lowered. There is a correlation between the domain of Fo-lowering and the scope of the wh-phrase. In a matrix wh-question, Fo-lowering after the wh-phrase continues until the end of the sentence, while in the case of an indirect wh-question, it stops at the end of the embedded clause. I account for this FIP- Wh-scope correspondence as follows. A pair of phonological rules is proposed that manipulate the prominence relations between semantically focalized phrases and post-focus phrases. These rules apply cyclically during the course of syntactic derivations, rather than waiting until the whole sentence is syntactically composed. Adopting the Multiple Spell-Out analysis (Chomsky, 2000, 2001b), I propose that the phonological rules for FIP formation apply to Spell-Out domains, rather than to a whole sentence. This proposal departs from previous analyses of FIP in Japanese (Truckenbrodt, 1995; Selkirk, 2003; Sugahara, 2003) in two respects: (1) it does not refer to prosodic phrasing; and (2) it is based on a cyclic model instead of a single-output model. The analysis makes the following prediction: if there are two wh-phrases that take different scopes in a single sentence, two independent FIPs will be created at different Spell-Out domains. This prediction was tested instrumentally. The results show that such a pitch contour is possible, and confirms other predictions as well.by Shinichiro Ishihara.Ph.D
Organizational Strategies to Integrate Gender Aspects Into International Development Programs: The Experience of Oxfam America
No full textIn this paper, the author illustrates the characteristics of various organizational strategies to incorporate gender aspects into international development programs. The author develops a case study of Oxfam America, a small non-governmental international development organization, through extensive internal document/literature reviews, supplemented by a series of interviews. Organizational strategies studied in the paper range from the creation of a gender unit, gender policy development, gendered strategic planning, and value reinforcing human agent management. The author reveals the limitations and strengths of each strategy and stresses the importance of strategic planning and management practices that emphasize gender aspects. The author concludes that a group of people, whose functions are internal gender advocates and gender advisers within their organizational structure, is vital for the institutionalization of gender. The creation of such a gender group/unit should be initiated by an organizational strategic plan, with stakeholders and the majority of staff members supporting the planning process. In addition, the author argues that a gender policy is a powerful tool to govern the direction of an organization leading toward a more gender-aware institution. However, the policy should not exist in isolation but be part of an organizational policy revision process in which management teams and staff members have extensive involvement. Finally, he attests that becoming a learning organization is an effective strategy when managing individual commitment and accountability toward gender, whose organization consists of staff members driven by the same values and sense of mission. Those who are trying to institutionalize gender perspectives successfully at their organizations will learn effective models and suggestions from the findings of this study
Molecular functions of metallothionein and its role in hematological malignancies
No full textAbstract Metallothionein (MT) was reported to be a potential negative regulator of apoptosis, and various reports have suggested that it may play roles in carcinogenesis and drug resistance, in at least a portion of cancer cells. The author summarizes the current understanding of the molecular functions of MT for tumor cell growth and drug resistance. These activities are regulated through intracellular metal ion modulation and free radical scavenging. Compared with analyses of solid tumors, few studies have analyzed the roles of MT in hematological malignancies. This review mainly describes the functions of MT in hematopoietic cells. Furthermore, through expression analyses of leukemias and lymphomas, the roles of MT in the biology of these diseases are particularly focused upon.</p
LiV{sub 2}O{sub 4}: A heavy fermion transition metal oxide
No full textThe format of this dissertation is as follows. In the remainder of Chapter 1, brief introductions and reviews are given to the topics of frustration, heavy fermions and spinels including the precedent work of LiV{sub 2}O{sub 4}. In Chapter 2, as a general overview of this work the important publication in Physical Review Letters by the author of this dissertation and collaborators regarding the discovery of the heavy fermion behavior in LiV{sub 2}O{sub 4} is introduced [removed for separate processing]. The preparation methods employed by the author for nine LiV{sub 2}O{sub 4} and two Li{sub 1+x}Ti{sub 2{minus}x}O{sub 4} (x = 0 and 1/3) polycrystalline samples are introduced in Chapter 3. The subsequent structural characterization of the LiV{sub 2}O{sub 4} and Li{sub 1+x}Ti{sub 2{minus}x}O{sub 4} samples was done by the author using thermogravimetric analysis (TGA), x-ray diffraction measurements and their structural refinements by the Rietveld analysis. The results of the characterization are detailed in Chapter 3. In Chapter 4 magnetization measurements carried out by the author are detailed. In Chapter 5, after briefly discussing the resistivity measurement results including the single-crystal work by Rogers et al., for the purpose of clear characterization of LiV{sub 2}O{sub 4} it is of great importance to introduce in the following chapters the experiments and subsequent data analyses done by his collaborators. Heat capacity measurements (Chapter 6) were carried out and analyzed by Dr. C.A. Swenson, and modeled theoretically by Dr. D.C. Johnston. In Chapter 7 a thermal expansion study using neutron diffraction by Dr. O. Chmaissem et al. and capacitance dilatometry measurements by Dr. C.A. Swenson are introduced. The data analyses for the thermal expansion study were mainly done by Dr. O. Chmaissem (for neutron diffraction) and Dr. C.A. Swendon (for dilatometry), with assistances by Dr. J.D. Jorgensen, Dr. D.C. Johnston, and S. Kondo the author of this dissertation. Chapter 8 describes nuclear magnetic resonance (NMR) measurements and analyses by Dr. A.V. Mahajan, R. Sala, E. Lee and Dr. F. Borsa. In the final chapter, a summary and discussion are given
Raising a Sense of Self-Worth: Action Research on Self-Compassion in an English Program
Get PDFThe suicide rate among Japanese youth has been dramatically increasing over the last decade due to the downturn economy and their lack of sense of self-worth. In this qualitative action research, the author introduces the concept of self-compassion to Japanese youth in a content-based English classroom as an attempt to raise their sense of self-worth. The research shows that self-compassion has a possibility of providing Japanese young people with more rational perceptions of themselves, creating an emotionally supportive environment, and allowing them to develop their self-awareness. The author concludes that it is this development of self-awareness that can raise the sense of self-worth, and English classrooms have a possibility of providing a place for this process. Additionally, the research reaffirms that the presence of compassionate others is also important to enhance the sense of self-worth
New Graphical Solution of Stress in the Ground under Foundations
Get PDFIn this article the author first discusses the graphical solutions of obtaining stresses in the ground under foundations proposed hitherto and then proposes 3 new simplified graphical methods by improving the methods of Burmister and Newmark and by transforming the scales in compliance with the coefficient of concentration according to Fröhlich, making practical application easier
Eliminating unphysical photon components from Dirac-Maxwell Hamiltonian quantized in the Lorenz gauge
Get PDFWe study the Dirac-Maxwell model quantized in the Lorenz gauge. In this gauge, the space of quantum mechanical state vectors inevitably adopt an indefinite metric so that the canonical commutation relation (CCR) is realized in a Lorentz covariant manner. In order to obtain a physical subspace, in which no negative norm state exists, the method first proposed by Gupta and Rimier is applied with mathematical rigor. It is proved that a suitably defined physical subspace has a positive semi definite metric, and naturally induces a physical Hilbert space with a positive definite metric. Then, the original Dime-Maxwell Hamiltonian defines an induced Hamiltonian on the physical Hilbert space which is essentially self-adjoint. (C) 2016 Elsevier Inc. All rights reserved
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