1,772 research outputs found

    The occurrence of ionospheric signatures of plasmaspheric plumes over different longitudinal sectors

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    Plasmaspheric plumes have ionospheric signatures and are observed as storm-enhanced density (SED) in global positioning system (GPS) total electron content (TEC). These ionospheric signatures have been primarily observed over the American sector and in a few limited examples over the European sector. This study examines the longitudinal occurrence frequency of plasmaspheric plumes. We analyzed all images from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) Extreme Ultraviolet Imager (EUV) databases for the first half of 2001 and identified a total of 31 distinct plume intervals observed during different storm events. Out of the total IMAGE EUV plumes that we identified, 12 were projected over North America, 10 over Asia, and the remaining 9 were over Europe and the Atlantic Ocean. Using ground-based GPS TEC from MIT\u27s Madrigal database, we searched for corresponding SED/TEC plumes at different longitudinal sector and found 12 ionospheric SED plume signatures over North America, 4 over Europe, and 2 over Asia. This indicates that the observation probability of an ionospheric SED plume when a plasmaspheric plume is seen is 100% in the American sector, 50% in the European sector, and 20% in the Asian sector. This could be due to the fact that the plumes may be either positioned beyond the limit of the ground-based GPS field of view, which happens mainly when there is less plasmaspheric erosion, or are too weak to be detected by the sparse number of GPS receivers over Asia. The in situ plasma densities from the available coincident defense metrological satellite program (DMSP) satellites were also used to study the characteristics of SED/TEC plume at DMSP orbiting altitude (i.e., ∼870 km). The TOPographic EXplorer (TOPEX) altimeter TEC also is used to identify the conjugate SED/plume signature over the Southern Hemisphere

    The limits of relational governance: Sales force strategies in the U.S. medical device industry

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    Research Summary: We explore how inter-organizational relationships shape firm boundary decisions. Using data on 545 U.S. medical device manufacturers’ product portfolios and sales governance choices (i.e., internal or external sales forces) from 1983 to 1996, we find relational capital between manufacturers and external sales forces influences future firm boundary decisions. Relational capital lowers the likelihood of integrating the sales function, but only when firms remain focused on the same product market. Further, launching an innovative product has a nuanced effect. For firms lacking relational capital, innovation increases the likelihood of sales integration. This pattern reverses as relational capital accumulates, but only when innovations are in the firm’s existing focal product market. Our findings suggest important limits on the effect of relational governance on firm strategy. Managerial Abstract: Choosing between in-house or external sales is a key strategic decision. In the medical device industry, this decision is particularly important because sales people are conduits between R&D and customers. For firms who initially choose external sales, the tradeoff between maintaining existing links (via external sales) and developing new, direct relationships (by bringing sales in-house) can change significantly as product portfolios change. Analyzing 545 U.S. medical device manufacturers from 1983 to 1996, we find that existing relationships with external sales forces reduce the likelihood of bringing sales in-house, but only when firms remain in the same product market, such as orthopedic implants. When firms launch products in new markets, especially innovations, they are more likely to bring sales in-house

    Ferrimagnetism in sputtered MnxCoGe thin films

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    Investigations into the magnetic properties of sputtered MnxCoGe films in the range 0.8 <= x <= 2.5 uncovered ferrimagnetic order, unlike the ferromagnetic order reported in bulk samples. These films formed hexagonal Ni2In-type structures in all measured compositions. While the Curie temperatures of the films are comparable to those of hexagonal bulk MnCoGe, here is a reduction in the magnetization of the MnxCoGe film relative to bulk MnCoGe, and a magnetization compensation point is observed in the x < 1 samples. To understand the behavior, we calculated the magnetic moments of Mn-antisite defects in MnCoGe with density-function theory calculations. Models constructed from the calculation suggest that films become ferrimagnetic due to the presence of Mn on the Co and Ge sites. In the x < 1 samples, these defects arose from the disorder in the films, whereas for x > 1, the excess Mn was driven onto the antisites and produced ferrimagnetic order.Comment: 8 pages, 7 figure

    Meningococcal vaccination: Recommendations of the advisory committee on immunization practices, United States, 2020

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    © 2020. This report compiles and summarizes all recommendations from CDC\u27s Advisory Committee on Immunization Practices (ACIP) for use of meningococcal vaccines in the United States. As a comprehensive summary and update of previously published recommendations, it replaces all previously published reports and policy notes. This report also contains new recommendations for administration of booster doses of serogroup B meningococcal (MenB) vaccine for persons at increased risk for serogroup B meningococcal disease. These guidelines will be updated as needed on the basis of availability of new data or licensure of new meningococcal vaccines. ACIP recommends routine vaccination with a quadrivalent meningococcal conjugate vaccine (MenACWY) for adolescents aged 11 or 12 years, with a booster dose at age 16 years. ACIP also recommends routine vaccination with MenACWY for persons aged ≥2 months at increased risk for meningococcal disease caused by serogroups A, C, W, or Y, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor (e.g., eculizumab [Soliris] or ravulizumab [Ultomiris]); persons who have anatomic or functional asplenia; persons with human immunodeficiency virus infection; microbiologists routinely exposed to isolates of Neisseria meningitidis; persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroups A, C, W, or Y; persons who travel to or live in areas in which meningococcal disease is hyperendemic or epidemic; unvaccinated or incompletely vaccinated first-year college students living in residence halls; and military recruits. ACIP recommends MenACWY booster doses for previously vaccinated persons who become or remain at increased risk. In addition, ACIP recommends routine use of MenB vaccine series among persons aged ≥10 years who are at increased risk for serogroup B meningococcal disease, including persons who have persistent complement component deficiencies; persons receiving a complement inhibitor persons who have anatomic or functional asplenia; microbiologists who are routinely exposed to isolates of N. meningitidis; and persons identified to be at increased risk because of a meningococcal disease outbreak caused by serogroup B. ACIP recommends MenB booster doses for previously vaccinated persons who become or remain at increased risk. In addition, ACIP recommends a MenB series for adolescents and young adults aged 16-23 years on the basis of shared clinical decision-making to provide short-term protection against disease caused by most strains of serogroup B N. meningitidis

    Survival of patients with subglottic squamous cell carcinoma

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    Objective: Subglottic squamous cell carcinoma is a rare subsite of laryngeal cancer that behaves more aggressively and portends a worse prognosis. Using a population-based cancer registry, our objective was to report overall survival (OS) and laryngectomy-free survival (LFS) in patients diagnosed with subglottic squamous cell carcinoma, and to determine whether primary laryngectomy results in improved survival. Methods: This retrospective population-based study considered patients with a new diagnosis of squamous cell carcinoma in the province of Ontario over a 15-year period (1995-2009). The Ontario Cancer Registry was examined for patients with the diagnosis of interest during the period of interest. Linked population-based databases were used to obtain patient demographics, comorbidity measures, staging, survival, and primary treatment with laryngectomy. Results: Of 4927 patients identified to have laryngeal carcinoma, 89 were defined as having primary subglottic carcinoma (1.8%). In the subglottic cohort, 68 patients were men (76.4%), and mean age at diagnosis was 68 years (interquartile range: 60-77 years). The 5-year OS was 47.2%, and the 5-year LFS was 31.5%. In 13 patients (15%), the primary treatment was laryngectomy, which, compared with primary radiation, did not predict for improved OS. No differences in OS or LFS were observed during the 15-year study period (OS p=0.42, LFS p=0.83). Conclusions: The survival of patients with subglottic carcinoma is poor and has remained stable over time (1995-2009). Compared with primary radiation, primary treatment with laryngectomy does not appear to improve OS

    REVIEW: Life-cycle, total-industry genetic improvement of feed efficiency in beef cattle: Blueprint for the Beef Improvement Federation

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    On a life-cycle basis, beef animals are able to consume large amounts of low-cost, low-quality forages relative to higher-cost concentrates compared with pigs and chickens. However, of the 3, beef is still more expensive to produce on a cost–per–edible pound basis. Accordingly, there is need for genetic programs and management changes that will improve efficiency, sustainability, and profitability of beef production. Options include improving reproductive rate, reducing feed used for maintenance, or both, while not reducing output. A goal for improving efficiency of feed utilization is to reduce the amount or proportion of feed used for maintenance. Such reduction is a target for genetic improvement, but such a goal does not include defining a single measure of efficiency. A single efficiency measure would likely lead to single-trait selection and not account for any potentially antagonistic effects on other production characteristics. Because we are not able to explain all variation in individual-animal intake from only knowledge of BW maintained and level of production, measuring feed intake is necessary. Therefore, our recommendation is that national cattle evaluation systems analyze feed intake as an economically relevant trait with incorporation of appropriate indicator traits for an EPD for feed intake requirements that could then be used in a multiple-trait setting such as in a selection index. With improvements in technology for measurement of feed intake, individual measures of feed intake should continually be collected to facilitate development of genetic predictors that enhance accuracy of prediction of progeny differences in national cattle evaluations

    Genetic Variance and Covariance Components for Feed Intake, Average Daily Gain, and Postweaning Gain in Growing Beef Cattle

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    Feed is the greatest cost for a beef cattle production enterprise. Data collection to determine feed efficiency of animals is also costly, because both gain and intake records are needed to calculate feed efficiency. Electronic intake monitoring systems such as GrowSafe or Insentec to collect feed intake data are expensive and thus limit the number of animals that can be tested. Scientists have worked to pinpoint optimal test durations for collecting both weight gain and feed intake records to lessen costs. A 70-day performance test is currently recommended for accurate calculation of efficiency, with growth data as the limiting factor. Research has suggested that a 35-day test is adequate to measure feed intake, but a test period of at least 70 days is suggested to measure gain with sufficient accuracy. The objective of this study was to estimate genetic parameters for growth and intake traits with particular attention to the relationship between on-test average daily gain (ADG) and national cattle evaluation postweaning gain (PWG). If the correlation between these two traits is strong, it could allow for the use of PWG as a proxy for ADG in the genetic evaluation of feed efficiency. This substitution would allow producers to reduce the length of the test required to measure feed intake accurately

    The impact of seasonal operating room closures on wait times for oral cancer surgery

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    Background Operating room slowdowns occur at specific intervals in the year as a cost-saving measure. We aim to investigate the impact of these slowdowns on the care of oral cavity cancer patients at a Canadian tertiary care centre. Methods A total of 585 oral cavity cancer patients seen between 1999 and 2015 at the London Health Science Centre (lhsc) Head and Neck Multidisciplinary Clinic were included in this study. Operating room hours and patient load from 2006 to 2014 were calculated. Our primary endpoint was the wait time from consultation to definitive surgery. Exposure variables were defined according to wait time intervals occurring during time periods with reduced operating room hours. Results Overall case volume rose significantly from 2006 to 2014 (p \u3c 0.001), while operating room hours remained stable (p = 0.555). Patient wait times for surgery increased from 16.3 days prior to 2003 to 25.5 days in 2015 (p = 0.008). Significant variability in operating room hours was observed by month, with lowest reported for July and August (p = 0.002). The greater the exposure to these months, the more likely patients were to wait longer than 28 days for surgery (odds ratio per day [or]: 1.07, 95% confidence interval [ci]: 1.05 to 1.10, p \u3c 0.001). Individuals seen in consultation preceding a month with below average operating room hours had a higher risk of disease recurrence and/or death (hazard ratio [hr]: 1.59, 95% ci: 1.10 to 2.30, p = 0.014). Conclusions Scheduled reductions in available operating room hours contribute to prolonged wait times and higher disease recurrence. Further work is needed to identify strategies maximizing efficient use of health care resources without negatively affecting patient outcomes
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