70 research outputs found
A Search for Ultra-High Energy Neutrinos and Cosmic Rays with ANITA-3
No full textThe Antarctic Impulsive Transient Antenna (ANITA) is a balloon borne radio inter- ferometer, designed to detect the impulsive Askaryan radiation created by ultra-high energy neutrinos interacting in the ice sheets of Antarctica. Previous flights of the experiment have demonstrated an unexpected sensitivity to cosmic rays, detecting the radio emission from geo-magnetically induced transverse currents in extended air showers. The third flight of ANITA (ANITA-3) took place during the austral summer of 2014-15. In this thesis I present two contributions to the ANITA-3 experiment, the tim- ing calibration of the digitizer electronics, and my implementation of a real-time interferometric event prioritizer using a GPU flown with the experiment. Finally, I present a search for neutrinos and cosmic rays in the ANITA-3 data set. No evidence of neutrino interactions is observed, with zero candidate events discovered on a background of 0.11 ± 0.07 leading to the world’s best limit on the ultra-high energy neutrino flux in the energy range 10^19 eV to 10^21 eV. Four isolated, predominantly horizontally polarised events are found in the data. Further work is required to confirm these events have all the properties consistent with radio emission induced by cosmic ray air shower
A fraction of barrier-to-autointegration factor (BAF) associates with centromeres and controls mitosis progression
No full textBarrier-to-Autointegration Factor (BAF) is a conserved nuclear envelope (NE) component that binds chromatin and helps its anchoring to the NE. Cycles of phosphorylation and dephosphorylation control BAF function. Entering mitosis, phosphorylation releases BAF from chromatin and facilitates NE-disassembly. At mitotic exit, PP2A-mediated dephosphorylation restores chromatin binding and nucleates NE-reassembly. Here, we show that in Drosophila a small fraction of BAF (cenBAF) associates with centromeres. We also find that PP4 phosphatase, which is recruited to centromeres by CENP-C, prevents phosphorylation and release of cenBAF during mitosis. cenBAF is necessary for proper centromere assembly and accurate chromosome segregation, being critical for mitosis progression. Disrupting cenBAF localization prevents PP2A inactivation in mitosis compromising global BAF phosphorylation, which in turn leads to its persistent association with chromatin, delays anaphase onset and causes NE defects. These results suggest that, together with PP4 and CENP-C, cenBAF forms a centromere-based mechanism that controls chromosome segregation and mitosis progression. © 2020, The Author(s)
Identifying Intentional Ambiguity
No full textIdentifying Intentional Ambiguity
It is widely acknowledged that certain genres in ancient Near Eastern literature including the Hebrew Bible are characterized by intense ambiguity. In particular, divination, Wisdom literature and erotic poetry thrive on a special type of ambiguity—“double-edged words”—in which a
single graphic or phonetic sequence is employed to convey a message and its precise opposite, at one and the same time.
However, it is often difficult to demonstrate that a specific case of “double-edged wording” is in fact intentional rather than a product of an eager reader’s over-interpretation. The proposed paper offers three criteria for identifying intentionality in the formulation of ambiguous texts, based on examples from Biblical and other ancient Near Eastern divinatory, Wisdom and poetic texts: (1) Ungrammaticality: Sometimes an author is forced to use an ungrammatical form in order to preserve two opposite meanings. This happens when smoothing the grammar would have been achieved only at the price of losing the ambiguity; (2) Multiple representation: At times the same exact ambiguity is evidenced in identical contexts, but in different words and by means of different sentence-structures (occasionally even in different languages, e.g., Hebrew and Aramaic); when it can be demonstrated that coincidence is highly unlikely, the argument for intentional crafting is strong; (3) Straussian “Art of Writing”: When the author addresses an issue that was demonstrably contentious (from the author’s perspective), potentially-subversive formulations are particularly suspect.
The intersection of two or three of these criteria in a single text strongly suggests intentionalit
Epitaxial deposition mechanism of barium fluoride on single crystal silicon substrate using molecular beam epitaxy
No full textThe deposition of films made of fluoride compounds has been a goal for researchers because of their application as insulators in integrated microelectronics and as substrates. Films of barium fluoride (BaF\sb2) have been grown directly on both (111), and (100) oriented silicon (Si) crystals. BaF\sb2 films of excellent quality grow oriented along the (111) direction regardless of the substrate orientation. The Si crystal has a lattice constant of 5.45 A in contrast with BaF\sb2 with a lattice constant of 6.20 A. It is difficult to explain how BaF\sb2 can be grown on Si using a simple atomic stacking mechanism. Strains at the interface due to differences in lattice constants should not allow the hetero-epitaxy system to exist.This work deals with the first attempt to explain how BaF\sb2 can be grown on Si by investigating the chemistry at the interface. X-ray photoelectron spectroscopy was used to analyze the interface between BaF\sb2 and Si. Results show that fluorine is not present at the interface but rather a barium-silicon compound is formed at the interface. X-ray diffraction measurements confirm the formation of a new compound at the interface. Further evidence of the chemical reaction at the interface is that by heating the BaF\sb2 films on Si, all of the film can be converted to the barium-silicon compound. This new Ba-Si film was used as a substrate for deposition of PbTe with excellent results. PbTe like BaF\sb2 has a lattice constant considerable larger that silicon (6.49 A). The PbTe films grew (100) oriented and had very little strain according to X-ray diffraction results. The results reported here suggest that a new procedure for making silicide films can be developed. Also the results can be used to explain the chemistry in other fluorides on Si.Source: Dissertation Abstracts International, Volume: 54-06, Section: B, page: 3162.Ph.D. American University 1992.Englis
The role of the Polybromo-associated BAF complex in development
No full textChromatin is dynamically regulated during development, where structural changes affect the transcription of genes required to promote different cell types. One of the chromatin regulatory factors responsible for transcriptional regulation during development is the SWItch/Sucrose Non-Fermentable (SWI/SNF) complex, an ATP-dependent chromatin remodeling factor conserved throughout eukaryotes. The catalytic subunit of this complex, BRG1, is shared in all three SWI/SNF complexes subfamilies and is essential for developing most cell lineages. Interestingly, many human developmental diseases have correlative or causative mutations in different SWI/SNF subunits. Many polybromo-associated BAF (pBAF) complex-specific subunit genetic alterations result in developmental failures in tissue-specific ways. This observation suggests that the pBAF complex plays a vital role in development and differentiation, and studying the pBAF complex may provide an opportunity to better understand gene regulation during development. In this mini-view, we will focus on the functions of pBAF-specific subunits and their influence on the development of various cell and tissue types by regulating developmental gene expression.The presentation of the authors' names and (or) special characters in the title of the pdf file of the accepted manuscript may differ slightly from what is displayed on the item page. The information in the pdf file of the accepted manuscript reflects the original submission by the author
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Analysis of a rare progeria variant of Barrier-to-autointegration factor in Drosophila connects centromere function to tissue homeostasis
No full textBarrier-to-autointegration factor (BAF/BANF) is a nuclear lamina protein essential for nuclear integrity, chromatin structure, and genome stability. Whereas complete loss of BAF causes lethality in multiple organisms, the A12T missense mutation of the BANF1 gene in humans causes a premature aging syndrome, called Néstor-Guillermo Progeria Syndrome (NGPS). Here, we report the first in vivo animal investigation of progeroid BAF, using CRISPR editing to introduce the NGPS mutation into the endogenous Drosophila baf gene. Progeroid BAF adults are born at expected frequencies, demonstrating that this BAF variant retains some function. However, tissue homeostasis is affected, supported by studies of the ovary, a tissue that depends upon BAF for stem cell survival and continuous oocyte production. We find that progeroid BAF causes defects in germline stem cell mitosis that delay anaphase progression and compromise chromosome segregation. We link these defects to decreased recruitment of centromeric proteins of the kinetochore, indicating dysfunction of cenBAF, a localized pool of dephosphorylated BAF produced by Protein Phosphatase PP4. We show that DNA damage increases in progenitor germ cells, which causes germ cell death due to activation of the DNA damage transducer kinase Chk2. Mitotic defects appear widespread, as aberrant chromosome segregation and increased apoptosis occur in another tissue. Together, these data highlight the importance of BAF in establishing centromeric structures critical for mitosis. Further, these studies link defects in cenBAF function to activation of a checkpoint that depletes progenitor reserves critical for tissue homeostasis, aligning with phenotypes of NGPS patients. © 2023, The Author(s).Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Analysis of microbial characterization in an upflow anaerobic sludge bed/biological aerated filter system for treating microcrystalline cellulose wastewater
No full textA two-stage UASB and 2-stage BAF series bioreactor was used for treating the microcrystalline cellulose (MCC) wastewater. The treating efficiency, dominant microbes. eubacterial and archaebacterial composition and cel5A, cel6B and bglC gene expression levels were examined using combined PCR-DGGE and real-time PCR technology. The results showed that under three MCC loads (1000, 2000 and 3000 mg L-1), the total MCC degradation efficiency of the UASB-BAF system was 82.0%, 83.5% and 70.5%, respectively. In different MCC load cases, the first stage UASB and BAF formed an approximate full-value cellulase system where cellulolytic microorganisms were the dominant flora, while the second stage UASB and BAF formed a low-value cellulase system where non-cellulolytic microorganisms were the dominant flora. Eubacteria were dominant in every UASB-BAF unit. The rate-limiting enzyme gene for MCC degradation in every unit was cel6B. These results will support the development of high efficiency bio-reactors for the degradation of MCC. (c) 2012 Elsevier Ltd. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000308056000010&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Agricultural EngineeringBiotechnology & Applied MicrobiologyEnergy & FuelsSCI(E)EIPubMed9ARTICLE60-6912
A simultaneous removal of beryllium and ammonium-nitrogen from smelting wastewater in bench- and pilot-scale biological aerated filter
No full textHeavy metal and NH4+-N co-contaminated wastewater are frequently found, and the presence of NH4+-N makes it extremely difficult to treat. In the present study, bench-scale and pilot-scale experiments were conducted to investigate the simultaneous removal of beryllium and NH4+-N from smelting wastewater by biological aerated filter (BAF) reactors. The results of the five-stage BAF reactors showed that the system could endure shock loadings. The average removal efficiency for beryllium and NH4+-N was 92.6% and 95.0%, respectively. Sequence extraction indicates that the primary removal mechanism in the first two reactors was precipitation, whereas the organic-bound fraction was predominant in the last three reactors due to the high accumulation rates of beryllium inside the microbial cells. Polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) and sequence analysis of 16S rDNA gene fragments showed that N-oxidizing bacteria (Nitrosomonas sp. and Beta proteobacterium CH24i) were primarily detected in the first two BAF reactors, in accordance with their high NH4+-N removal efficiencies, and metal-resistant bacteria (Actinobacteria sp.) were found in all BAF reactors. (C) 2012 Elsevier B.V. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000312617100031&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Engineering, EnvironmentalEngineering, ChemicalSCI(E)EI2ARTICLE263-27021
Identity and dislocation in Caribbean women's literature: a study of the writings of Velma Pollard
No full textJamaican-born Velma Pollard has been publishing poetry and short stories for nearly
thirty years. Her first poems appeared in the 1970s, her first volume of short stories in
1989, and her first novel in 1994. Despite this considerable literary output, in the evergrowing
critical literature on Caribbean women's writing Pollard's work has not attracted
any of the scholarly treatment accorded to other writers. Given this lack of critical
attention to Pollard's considerable body of work, this thesis aims to provide the first
detailed and contextualised study of her writings (excluding the majority of her poetry
and of her writings on linguistics), and to accord Pollard the recognition her work
deserves.
Chapter 1 of this thesis situates Pollard's writings in the context of Caribbean
(women's) literature, and writings on identity, dislocations and (Caribbean) migration. I
argue that Pollard's principal contribution to Caribbean literature is found in her
engagement with two main subjects, return migration and relationships (male-female and
female-female), within a wider context of debates on identity and dislocation.
Chapter 2 introduces Pollard's work by way of a general discussion of her novella
Karl, which won the Casa de las Americas literary award in 1992. I consider Karl to be
central to Pollard's work, not least because it features many of the themes explored by
her later writings, including her novel, Homestretch, which is the subject of Chapter 3.
Pollard's first novel, Homestretch, which was published in 1994, explores the themes
of identity and dislocation through the experiences of 'return migrants' and 'repeat
migrants' and their comparison of life in England, the United States and Jamaica. The
novel chronicles how these migrants come to reconnect with and accept their cultural
heritage.
In chapters 4 and 5 I discuss selected stories taken from Pollard's two collections
of short stories, Considering Woman ('Cages', 'My Sisters', 'My Mother', and 'Gran') and
from Karl and Other Stories ('A Night's Tale', 'Miss Chandra', 'Betsy Hyde', and 'Altamont
Jones'). In these stories Pollard explores male-female relationships and the lives of
several generations and a wide range of Caribbean women and men. Pollard utilises the
West Indian setting, speech, situations and conflicts in these stories to graphically
describe familiar Caribbean role models and to provide a narrative and literary
examination of the frustrations and conflicting desires of women in the region.
In my conclusion, I address the ethnographic quality and significance of her work,
and its contribution to an understanding of the Caribbean
Necrotic pyknosis is a morphologically and biochemically distinct event from apoptotic pyknosis
No full textClassification of apoptosis and necrosis by morphological differences has been widely used for decades. However, this usefulness of this method has been seriously questioned in recent years, mainly due to a lack of functional and biochemical evidence to interpret the morphology changes. To address this matter, we devised genetic manipulations in Drosophila to study pyknosis, a process of nuclear shrinkage and chromatin condensation that occurs in apoptosis and necrosis. By following the progression of necrotic pyknosis, we surprisingly observed a transient state of chromatin detachment from the nuclear envelope, followed by the nuclear envelope completely collapsing onto chromatin. This phenomenon led us to discover that phosphorylation of barrier-to-autointegration factor (BAF) mediates this initial separation of nuclear envelope from chromatin. Functionally, inhibition of BAF phosphorylation suppressed necrosis in both Drosophila and human cells, suggesting that necrotic pyknosis is conserved in the propagation of necrosis. In contrast, during apoptotic pyknosis the chromatin did not detach from the nuclear envelope and inhibition of BAF phosphorylation had no effect on apoptotic pyknosis and apoptosis. Our research provides the first genetic evidence supporting a morphological classification of apoptosis and necrosis through different forms of pyknosis.Ministry of Science and Technology of the People's Republic of China [2013CB530700]; National Natural Science Foundation of China for Distinguished Young Scholars [81325007]SCI(E)[email protected]; [email protected]
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