879 research outputs found

    Class Day 1963 Speech Transcript: Open Yourself Wide as the Sky

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    Mr. Chairman, Dr. Jacobs, honored guests, college officers, members of the administrative staff, faculty, parents, friends, and fellow classmates:..

    The Inverse-Compton And Extragalactic Components Of The Diffuse Gamma-Ray Emission

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    We present spectra of the inverse-Compton and extragalactic components of the high-energy gamma-radiation based on an analysis of the emission at high galactic latitudes (∣\vertb∣\vert ≄\geq 30deg⁥30\deg). We correlate the gamma-ray intensity with a model consisting of an isotropic component, a component proportional to the 408 MHz synchrotron radiation, and a component proportional to atomic hydrogen (H I) column density with different emissivities in eight galactic octants. The spectrum of gamma-radiation that is correlated with the H I column density indicates that this component originates in cosmic-ray/matter interactions. The cosmic-ray electrons which produce the 408 MHz radio continuum emission also produce gamma-radiation through inverse-Compton interactions with interstellar photons. By correlating the gamma-radiation with the 408 MHz continuum, we measure the spectrum and absolute intensity of the IC emission. The isotropic component gives us the spectrum and intensity of the extragalactic gamma-radiation. We discuss interpretation of the extragalactic spectrum.Comment: 21 page Postscript file, 10 Postscript figure

    Groundwork| [Short stories]

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    An analysis of motion and time study training as given by colleges and industrial organizations

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    M.S.Donald B. Wilco

    “Karajarri Healthy Country Study Tour Canada British Columbia”

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    In this Seminar Anna Dwyer and Joe Edgar will talk about their recent cultural exchange trip and study tour to Canada. The purpose of the exchange was to visit First Nation communities in British Columbia (Canada) to engage with, learn from, and share experiences in improved land, water and cultural management of our respective traditional homelands. The Karajarri Traditional Owners provided information on the activities of the Karajarri Rangers and the Karajarri indigenous Protected Area (IPA). Anna and Joe will share their experiences exchanging information on strengthening the social and human capital within Indigenous land management programs; Increasing youth and school integration; building effective community governance structures; leadership development, support and networking; maintaining and strengthening customary law; and sharing Karajarri culture, dance and song to establish new working relationships

    Syncope or Seizure?

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    Syncope is a common complaint in the emergency departments, accounting for 1-2% of visits, and can approach admission rates of a staggering 85%. The causes and conditions can be numerous, ranging from benign to life threatening. A good background history can go a long way in determining the etiology of the patient’s syncope. We describe a case of an elderly male who presented with a reported chief complaint of seizures, another syncope-mimic seen in the emergency department. He had a history of CAD, HTN, AAA, and osteoarthritis but no prior history of cardiac arrhythmia, MI, or structural heart disease. The wife noticed collapse followed by seizure-like activity after opening the refrigerator. The initial EKG was non-specific. During his course in the ED there was a witnessed syncopal episode with upper extremity shaking and return to mental baseline within a minute of the event. A repeat EKG showed complete heart block. Seizures are a common presentation and chief complaint in the emergency department. It is easy to get tunnel vision in the clinical pathway and treatment plan. Other less common presentations of loss of consciousness with rhythmic shaking include convulsive syncope and should be considered. It is important to cast a wide net in the initial workup and always consider convulsive syncope, especially in an elderly patient with risk factors

    Anti-Cancer Drugs Effect on Quasi-palindrome Mutations in Escherichia coli

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    Cancer is one of the world\u27s largest health problems in today’s age. The Global Burden of Disease estimates that 10 million people died as a result of cancer per year (IHME). Although there are many treatments for different types of cancer, many of the drugs used are known to have severe side effects. These known consequences include hair loss, nausea, and, unfortunately, an increase in DNA mutation, which can trigger other classes of diseases. One class of mutations that have been studied and linked to a form of cancer is Quasi-palindrome template switch mutations. Quasi-palindromes are nearly perfect inverted repeats of nucleotides able to form DNA secondary structures. These Hairpins are an example of a secondary DNA structure made by DNA repeats and are known to block the DNA replication fork (VOINEAGU et al. 2008). Once DNA replication is blocked by these secondary DNA structures, the DNA replication fork needs to find a solution to continue the replication process. At some frequency, DNA polymerase (responsible for replicating the DNA) can use alternative DNA strands as templates to make more DNA. One alternative method is called “Template-switching”, and it results in a mutation that creates a perfect palindrome from a quasi-palindromic sequence. Previous work has linked anti-cancer drugs such as 5-azacytidine to an increase of QP mutations (Laranjo 2018). Therefore, I am interested in analyzing other anti-cancer drugs and their potential to cause QP mutations. Using an FDA approved drug library, with over 300 different drugs, we will select anti-cancer drugs to screen for QP mutators. We have constructed a QP reporter in E. coli that is specific for QP mutations (Laranjo 2017). To understand the effect of anti-cancer drugs during DNA replication is critical to give us an understanding of potential side effects for patients undergoing chemotherapy

    In Situ Enrichment and Epitaxial Growth of 28Si Films via Ion Beam Deposition

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    Isotopically enriched 28Si is an ideal material for solid state quantum computing because it interacts weakly with the spin states of embedded qubits (quantum bits) resulting in long coherence times. This is the result of eliminating the roughly 4.7 % 29Si isotopes present in natural abundance Si, which possesses nuclear spin I = 1/2 that is disruptive to qubit operation. However, high-quality 28Si is scarce and the degree to which it improves the performance of a qubit is not well understood. This leads to an important question in the Si-based quantum information field, which can be stated as "how good is good enough?" regarding the perfection of 28Si as a host medium for qubits. The focus of this thesis is to engineer a material that can address this question, specifically in terms of the enrichment. Secondary requirements for ideal 28Si films that are also pursued are crystalline perfection and high chemical purity. I report on the production and characterization of 28Si thin films that are the most highly enriched of any known 28Si material ever produced with a maximum 28Si enrichment of 99.9999819(35) % and a residual 29Si isotopic concentration of 1.27(29) x 10^-7. A hyperthermal energy ion beamline is used to produce this extreme level of enrichment starting from a natural abundance silane gas (SiH4) source. The Si is enriched in situ by mass separating the ions in a magnetic field just before deposition onto Si(100) substrates. Initial proof of principle experiments enriching 22Ne and 12C were also conducted. In the course of achieving this 28Si enrichment, I also pursue the epitaxial deposition of 28Si thin films. Characterizations of the film morphology and crystallinity are presented showing that smooth, epitaxial 28Si films are achieved using deposition temperatures between 349 C and 460 C. Crystalline defects present in these films include {111} stacking faults. When using higher deposition temperatures, I find that trace impurity compounds such as SiC cause step pinning and faceting of the growth surface leading to severely rough films. Assessments of the chemical purity of 28Si films are also presented, which show major impurities N, C, and O are present in the purest film at an atomic concentration of approximately 1 x 10^19 cm^-3, resulting in a Si purity of 99.96(2) %. Additionally, I introduce a model that describes the residual 29Si and 30Si in 28Si films, i.e. the enrichment, as the result of adsorption of diffusive natural abundance SiH4 gas from the ion source into the 28Si films during deposition. This model correlates the measured enrichments of 28Si films with the SiH4 partial pressures during deposition. An incorporation fraction for SiH4 adsorption at room temperature of s = 6:8(3) x 10^-4 is extracted. Finally, the temperature dependence of the sample enrichment is analyzed using a thermally activated incorporation model that gives an activation energy of Ec = 1.1(1) eV for the reactive sticking coefficient of SiH4
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