712 research outputs found

    Dollarizing The Cash Conversion Cycle

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    For most companies to be financially successful, it is critically important that operating cash flows be effectively managed. The Cash Conversion Cycle (CCC) is a traditional tool that companies use to measure the average time required for operating cash flows to cycle from cash out for the payment of payables and back to cash flow in from the collection of receivables. Knowledge that the rate their operating cash flow is speeding up or slowing down, as indicated by a decreasing or increasing CCC, while useful information, is of limited value to the company. The CCC indicates nothing about the absolute dollar amount of the cash flow. This paper illustrates a method by which the current year actual CCC and the next year target CCC, along with a few other items of data, can be used to forecast the dollar amount of the next year’s operating cash flows. The extension of the CCC to enable it to help forecast the dollar amount of operating cash flows makes the CCC more useful to companies attempting to effectively manage operating cash flows

    How Do Quantitative And Qualitative Factors Influence The Selection Of Comparable, Competitive, And Aspirant Groups Under The Proposed AACSB Accreditation Maintenance Process?

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    The AACSB Blue Ribbon Committee on Accreditation Quality was “formed to do a thorough review of AACSB International's accreditation standards and procedures and to propose changes appropriate for global quality leadership in the next decade...” Within the proposal from the Blue Ribbon Committee is a change from a reaffirmation process with a site visit every ten years to a maintenance program resulting in a team visit in the sixth year of the cycle. Under the old standards applicants were required to submit “to the appropriate accreditation committee chair, in care of the AACSB International office, five nominations for each team role; i.e., five names for chair, five names for advisor, five for member, and if accounting accreditation were applicable, five names for vice-chair and five names for accounting advisor.” The proposed standards include a team selection process whereby the “applicant submits three comparison groups selected from members of the Accreditation Council... AACSB International will develop an on-line system to assist the applicant to identify potential comparison schools, officially select schools for each comparison group, and continuously maintain comparison group listings in an AACSB International database. Some information is currently available. The on-line service, www.aacsb.edu/knowledgeservices, offers advanced search functions that produce institution lists based on optionally selected criteria.” This AACSB provided information as well as information from other sources constitutes the basis for the recommended comparison group selection process

    Microwave field distribution in a magic angle spinning dynamic nuclear polarization NMR probe

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    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B[subscript 1S]) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B[subscript 1S] field is 13 μT/W[superscript 1/2], where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is γ[subscript S]B[subscript 1S] = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (ϵ) vs. ω[subscript 1S]/(2π) for a sample of [superscript 13]C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment.National Institutes of Health (U.S.) (Grant EB002804)National Institutes of Health (U.S.) (Grant EB003151)National Institutes of Health (U.S.) (Grant EB002026)National Institutes of Health (U.S.) (Grant EB001960)National Institutes of Health (U.S.) (Grant EB001035)National Institutes of Health (U.S.) (Grant EB004866)National Science Foundation (U.S.). Graduate Research Fellowshi

    Calibrating CHIME, A New Radio Interferometer to Probe Dark Energy

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    The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral hydrogen in the frequency range 400 -- 800\,MHz over half of the sky, producing a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 -- 2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that will yield constraints on the BAO power spectrum and provide a test-bed for our calibration scheme. I will discuss the CHIME calibration requirements and describe instrumentation we are developing to meet these requirements

    Dynamic nuclear polarization at 9 T using a novel 250 GHz gyrotron microwave source

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    In this communication, we report enhancements of nuclear spin polarization by dynamic nuclear polarization (DNP) in static and spinning solids at a magnetic field strength of 9 T (250 GHz for g = 2 electrons, 380 MHz for [superscript 1]H). In these experiments, [superscript 1]H enhancements of up to 170 ± 50 have been observed in 1-[superscript 13]C-glycine dispersed in a 60:40 glycerol/water matrix at temperatures of 20 K; in addition, we have observed significant enhancements in [superscript 15]N spectra of unoriented pf1-bacteriophage. Finally, enhancements of ~17 have been obtained in two-dimensional [superscript 13]C–[superscript 13]C chemical shift correlation spectra of the amino acid U–[superscript 13]C, [superscript 15]N-proline during magic angle spinning (MAS), demonstrating the stability of the DNP experiment for sustained acquisition and for quantitative experiments incorporating dipolar recoupling. In all cases, we have exploited the thermal mixing DNP mechanism with the nitroxide radical 4-amino-TEMPO as the paramagnetic dopant. These are the highest frequency DNP experiments performed to date and indicate that significant signal enhancements can be realized using the thermal mixing mechanism even at elevated magnetic fields. In large measure, this is due to the high microwave power output of the 250 GHz gyrotron oscillator used in these experiments.Natural Sciences and Engineering Research Council of Canada (Postgraduate Scholarship Fellowship)National Institutes of Health (U.S.) (Grant GM-35382)National Institutes of Health (U.S.) (Grant GM-55327)National Institutes of Health (U.S.) (Grant RR-00995

    An Infrared Coronagraphic Survey for Substellar Companions

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    We have used the F160W filter (1.4-1.8 um) and the coronagraph on the Near-InfraRed Camera and Multi-Object Spectrometer (NICMOS) on the Hubble Space Telescope (HST) to survey 45 single stars with a median age of 0.15 Gyr, an average distance of 30 pc, and an average H-magnitude of 7 mag. For the median age we were capable of detecting a 30 M_Jup companion at separations between 15 and 200 AU. A 5 M_Jup object could have been detected at 30 AU around 36% of our primaries. For several of our targets that were less than 30 Myr old, the lower mass limit was as low as a Jupiter mass, well into the high mass planet region. Results of the entire survey include the proper motion verification of five low-mass stellar companions, two brown dwarfs (HR7329B and TWA5B) and one possible brown dwarf binary (Gl 577B/C).Comment: 11 figures, accepted by A

    Valvuloarterial Impedence, Strain, Exercise, and AS

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    Background - In asymptomatic patients with severe aortic stenosis and preserved left ventricular ejection fraction, we sought to assess the incremental prognostic value of resting valvuloarterial impedence (Zva) and left ventricular global longitudinal strain (LV-GLS) to treadmill stress echocardiography. Methods and Results - We studied 504 such patients (66±12 years, 78% men, 32% with coronary artery disease who underwent treadmill stress echocardiography between 2001 and 2012. Clinical and exercise variables (% of age-sex predicted metabolic equivalents [%AGP-METs]) were recorded. Resting Zva ([systolic arterial pressure+mean aortic valve gradient]/[LV-stroke volume index]) and LV-GLS(measured offline using Velocity Vector Imaging, Siemens) were obtained from the baseline resting echocardiogram. Death was the primary outcome. There were no major adverse cardiac events during treadmill stress echocardiography. Indexed aortic valve area, Zva, and LV-GLS were 0.46±0.1 cm2/m2, 4.5±0.9 mm Hg/mL per m2 and -16±4%, respectively; only 50% achieved >100% AGP-METs. Sixty-four percent underwent aortic valve replacement. Death occurred in 164 (33%) patients over 8.9±3.6 years (2 within 30 days of aortic valve replacement). On multivariable Cox survival analysis, higher Society of Thoracic Surgeons score (hazard ratio or HR 1.06), lower % AGP-METS (HR 1.16), higher Zva (HR 1.25) and lower LV-GLS (HR 1.12) were associated with higher longer-term mortality, while aortic valve replacement (HR 0.45) was associated with improved survival (all P<0.01). Sequential addition of ZVa and LV-GLS to clinical model (Society of Thoracic Surgeons score and %AGP-METs) increased the c-statistic from 0.65 to 0.69 and 0.75, respectively, both P<0.001); findings were similar in the subgroup of patients who underwent aortic valve replacement. Conclusions - In asymptomatic patients with severe aortic stenosis undergoing treadmill stress echocardiography, LV-GLS and ZVa offer incremental prognostic value

    Ensuring Survey Research Data Integrity in the Era of Internet Bots

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    We used an internet-based survey platform to conduct a cross-sectional survey regarding the impact of COVID-19 on the LGBTQ + population in the United States. While this method of data collection was quick and inexpensive, the data collected required extensive cleaning due to the infiltration of bots. Based on this experience, we provide recommendations for ensuring data integrity. Recruitment conducted between May 7 and 8, 2020 resulted in an initial sample of 1251 responses. The Qualtrics survey was disseminated via social media and professional association listservs. After noticing data discrepancies, research staff developed a rigorous data cleaning protocol. A second wave of recruitment was conducted on June 11–12, 2020 using the original recruitment methods. The five-step data cleaning protocol led to the removal of 773 (61.8%) surveys from the initial dataset, resulting in a sample of 478 participants in the first wave of data collection. The protocol led to the removal of 46 (31.9%) surveys from the second two-day wave of data collection, resulting in a sample of 98 participants in the second wave of data collection. After verifying the two-day pilot process was effective at screening for bots, the survey was reopened for a third wave of data collection resulting in a total of 709 responses, which were identified as an additional 514 (72.5%) valid participants and led to the removal of an additional 194 (27.4%) possible bots. The final analytic sample consists of 1090 participants. Although a useful and efficient research tool, especially among hard-to-reach populations, internet-based research is vulnerable to bots and mischievous responders, despite survey platforms’ built-in protections. Beyond the depletion of research funds, bot infiltration threatens data integrity and may disproportionately harm research with marginalized populations. Based on our experience, we recommend the use of strategies such as qualitative questions, duplicate demographic questions, and incentive raffles to reduce likelihood of mischievous respondents. These protections can be undertaken to ensure data integrity and facilitate research on vulnerable populations
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