Properties of Metallic Helimagnets

This dissertation investigates various aspects of helimagnets. Helimagnets are magnets with spins aligned in helical order at low temperatures. It exists in materials of crystal structure lacking the spatial inversion symmetry. The helical order is due to the Dzyaloshinskii-Moriya (DM) mechanism. Examples of helimagnets include MnSi, FeGe and Fe1-xCoxSi. A field theory appropriate for such magnets is used to derive the phase diagram in a mean-field approximation. The helical phase, the conical phase, the columnar phase and the non-Fermi-liquid (NFL) region in the paramagnetic phase are discussed. It is shown that the orientation of the helical vector along an external magnetic field within the conical phase occurs via two distinct phase transitions. The columnar phase, believed to be a Skyrmion lattice, is found to exist as Abrikosov Skyrmions near the helimagnetic phase boundary, and the core-to-core distance is estimated. The Goldstone modes that result from the long-range order in the various phases are determined, and their consequences for electronic properties, in particular, the specific heat, single-particle relaxation rate and the electrical conductivity, are derived. In addition, Skyrmion gases and lattices in helimagnets are studied, and the size of a Skyrmion in various phases is estimated. For isolated Skyrmions, the long distance tail is related to the magnetization correlation functions and exhibits power-law decay if the phase spontaneously breaks a continuous symmetry, but decays exponentially otherwise. The size of a Skyrmion is found to depend on a number of length scales. These length scales are related to the strength of DM interaction, the temperature, and the external magnetic field

The troubles of David and his house: textual and literary studies of the synoptic stories of Saul and David in Samuel-Kings and Chronicles

The aim of this thesis is to evaluate an almost two-century old view of current Old Testament scholarship on the interrelationship between the books of Samuel-Kings and the books of Chronicles (Chr), which claims that the author of Chronicles (the Chr) based his work on the former corpus in more or less the existing form. The evaluation is preceded by a preliminary investigation into the grounds upon which that view has been accepted to show that it is based mainly on the relative dating of the history of religion as depicted in the two historiographical works and the supposed relative historical values of the two works, neither of which guarantees Chr's dependence on SamuelKings. It is astonishing to find that the received view is not based on detailed textual and literary comparison of the two works in general, the parallel texts in particular. Thus, instead of attacking the historical conclusions which are derived from the text, an investigation is offered of whether or not the prevailing view is also supported by detailed textual and literary study of some three chapters of parallel texts (1 Chr 10-12 and their counterparts in the books of Samuel).In the first chapter the textual and literary connections of the two versions of Saul's final battle (1 Sam 31 and 1 Chr 10) with their narrative contexts are explored to show that whereas the Samuel pluses and variants are mainly connected with accounts in which David's innocence in the demise of Saul and his house is defended, the Chr variants are mainly connected with stories before David's estrangement from Saul. In the second chapter the two versions of David's capture of Jerusalem (2 Sam 5.1-10 and 1 Chr 11.1-9) are submitted to similar scrutiny to show that the enigmatic extra references to "the blind and the lame" in the Samuel version are connected with a tendentious account of the story of the house of Eli ("the blind") and with the narrative of David's showing royal hospitality to Mephibosheth ("the lame"). Then the two versions of the list of David's mighty men (2 Sam 23.8-37 and 1 Chr 11.10-12.40) are studied in the third chapter to show that there are connections between the Succession Narrative and Samuel's list and that the account of David's seeking refuge under Achish in 1 Samuel has been split into two and also that Samuel's account of David's stay with Achish is more apologetic than Chr's account. Since the Samuel pluses and variants have links with stories in which blood guilt of David or his throne is involved, a thematic study of these materials—i.e. most of the History of David's Rise plus the Succession Narrative—is offered in the fourth and the fifth chapters to show that they form a thematically rather unified narrative and that they were probably from the same author. Since it is practically impossible for the Chr to remove very large text blocks from Samuel-Kings together with their subtle cross-references at the same time, the fact that none of these cross-references remains in Chr forces us to draw the inevitable conclusion that all those materials alluded to by these cross-references were originally absent from the Chr's Vorlag

Generation of Innovative and Sparse Encoding Vectors for Broadcast Systems with Feedback

In the application of linear network coding to wireless broadcasting with feedback, we prove that the problem of determining the existence of an innovative encoding vector is NP-complete when the finite field size is two. When the finite field size is larger than or equal to the number of users, it is shown that we can always find an encoding vector which is both innovative and sparse. The sparsity can be utilized in speeding up the decoding process. An efficient algorithm to generate innovative and sparse encoding vectors is developed. Simulations show that the delay performance of our scheme with binary finite field outperforms a number of existing schemes in terms of average and worst-case delay.Comment: 5 pages, 4 figures, accepted for publication in the Proc. of IEEE ISIT 201

Expression and functional characterization of the putative protein 8b of the severe acute respiratory syndrome-associated coronavirus

AbstractSARS 8b is one of the putative accessory proteins of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) with unknown functions. In this study, the cellular localization and activity of this estimated 9.6kDa protein were examined. Confocal microscopy results indicated that SARS 8b is localized in both nucleus and cytoplasm of mammalian cells. Functional study revealed that overexpression of SARS 8b induced DNA synthesis. Coexpression of SARS 8b and SARS 6, a previously characterized SARS-CoV accessory protein, did not elicit synergistic effects on DNA synthesis

Overexpression of cytochrome P450 1A1 and its novel spliced variant in ovarian cancer cells: alternative subcellular enzyme compartmentation may contribute to carcinogenesis

Epithelial ovarian cancer derived from the human ovarian surface epithelium (HOSE) is the leading cause of death from gynecologic malignancies among American women. Metabolic activation of endogenous and exogenous chemicals by cytochrome P450 (CYP) class I enzymes has been implicated in its etiology. In this study, we showed overexpression of CYP1A1 mRNA, but not CYP1B1 transcripts, in ovarian cancer cell lines when compared with primary cultures or immortalized HOSE cell lines. Importantly, we identified a novel, enzymatically active, spliced variant of CYP1A1 (CYP1A1v) formed by excision of an 84-bp cryptic intron in exon 2. CYP1A1v is overexpressed in ovarian cancer cell lines and exhibits a unique subcellular distribution restricted to the nucleus and mitochondria, contrary to the endoplasmic reticulum localization of the wild-type enzyme. In concordance, total CYP1A1 activity, as measured by the ethoxyresorufin O-deethylase assay, was detected in mitochondrial, nuclear, and microsomal fractions of ovarian cancer cells but was notably absent in all subcellular fractions of HOSE cells. Immunocytochemistry studies in 30 clinical specimens revealed overexpression of CYP1A1 in various types of ovarian cancers compared with benign epithelia and frequent localization of the enzyme to cancer cell nuclei. Forced expression of CYP1A1wt or CYP1A1v in HOSE cells resulted in nuclear localization of the enzyme and acquisition of anchorage-independent growth, which was further exacerbated following exposure to benzo(a)pyrene or 17beta-estradiol. Collectively, these data provided the first evidence that CYP1A1 overexpression and alternative splicing could contribute to ovarian cancer initiation and progression

An Intelligent Clinical Decision Support System for Assessing the Needs of a Long-Term Care Plan

With the global aging population, providing effective long-term care has been promoted and emphasized for reducing the hospitalizations of the elderly and the care burden to hospitals and governments. Under the scheme of Long-term Care Project 2.0 (LTCP 2.0), initiated in Taiwan, two types of long-term care services, i.e., institutional care and home care, are provided for the elderly with chronic diseases and disabilities, according to their personality, living environment and health situation. Due to the increasing emphasis on the quality of life in recent years, the elderly expect long-term care service providers (LCSP) to provide the best quality of care (QoC). Such healthcare must be safe, effective, timely, efficiently, diversified and up-to-date. Instead of supporting basic activities in daily living, LCSPs have changed their goals to formulate elderly-centered care plans in an accurate, time-efficient and cost-effective manner. In order to ensure the quality of the care services, an intelligent clinical decision support system (ICDSS) is proposed for care managers to improve their efficiency and effectiveness in assessing the long-term care needs of the elderly. In the ICDSS, artificial intelligence (AI) techniques are adopted to distinguish and formulate personalized long-term care plans by retrieving relevant knowledge from past similar records

Linear Network Code for Erasure Broadcast Channel with Feedback: Complexity and Algorithms

Abstract-This paper investigates the construction of linear network codes for broadcasting a set of data packets to a number of users. The links from the source to the users are modeled as independent erasure channels. Users are allowed to inform the source node whether a packet is received correctly via feedback channels. In order to minimize the number of packet transmissions until all users have received all packets successfully, it is necessary that a data packet, if successfully received by a user, can increase the dimension of the vector space spanned by the encoding vectors he or she has received by one. Such an encoding vector is called innovative. To reduce decoding complexity, sparse encoding vectors are preferred, since the sparsity can be exploited when solving systems of linear equations. Generating a sparsest encoding vector with large finite field size, however, is shown to be NP-hard. An approximation algorithm is constructed. For binary field, heuristic algorithms are also proposed. Index Terms-Erasure broadcast channel, network coding, computational complexity

Ordered Phases of Itinerant Dzyaloshinsky-Moriya Magnets and Their Electronic Properties

A field theory appropriate for magnets that display helical order due to the Dzyaloshinsky-Moriya mechanism, a class that includes MnSi and FeGe, is used to derive the phase diagram in a mean-field approximation. The helical phase, the conical phase in an external magnetic field, and recent proposals for the structure of the A-phase and the non-Fermi-liquid region in the paramagnetic phase are discussed. It is shown that the orientation of the helical pitch vector along an external magnetic field within the conical phase occurs via two distinct phase transitions. The Goldstone modes that result from the long-range order in the various phases are determined, and their consequences for electronic properties, in particular the specific heat, the single-particle relaxation time, and the electrical and thermal conductivities, are derived. Various aspects of the ferromagnetic limit, and qualitative differences between the transport properties of helimagnets and ferromagnets, are also discussed.Comment: 22pp, 8 eps fig