Navy Satellite Communication System - In Transition

In the space age, satellite systenf engineers and program managers are blessed by ever improving satellite and ground system tech- nology and performance, and are challenged by the changes in their systems required to take advantage of these improvements. An extended period of time is required to bring total satellite communications systems to maturity, or full operational capability. Consequently, as today*s systems are being deployed, the follow-on programs are moving through early development and offering improvements and tradeoffs requiring careful analysis and transition planning. The several Navy SATCOM programs in being and in development, present the full spectrum of challenge for system engineering, program management and long-range planning. Solutions are being developed to unique Navy transitional issues within the framework of the total Defense MILSATCOM Architecture, Significant gains in overall satellite communications capability for the near term through the 1990\u27s will result from the coordinated deployment and use of current assets, the development of more capable future systems, and an optimal transition to these systems. This paper reviews several Navy SATCOM transition issues currently being addressed as the Shuttle introduces a new dimension to space age communications

Anomalous scaling of mesoscale tropospheric humidity fluctuations

Water vapor fluctuations are measured and analyzed at an unprecedented 10-m resolution throughout the troposphere. Computation of structure functions shows that specific humidity variations observed by research aircraft over the Pacific Ocean exhibit anomalous scaling from about 50 m to 100 km in horizontal range. The scaling laws show different characteristics for the marine boundary layer, the tropical free troposphere, and the extratropical free troposphere. More specifically, boundary-layer humidity fluctuations are less smooth and more stationary than those in the free troposphere, while the extratropical free tropospheric variations are less intermittent than those in the other two regions. The anomalous scaling results argue against passive advection by a spatially smooth flow (chaotic advection) at these scales.United States. National Aeronautics and Space Administration (Grant NAG1-2173)United States. National Aeronautics and Space Administration (Grant NAG1-1901

Bostonia. Volume 6

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Characterizations of tropospheric turbulence and stability layers from aircraft observations

[1] Velocity, temperature, and specific humidity data collected by aircraft at 20-Hz resolution are analyzed for stability and turbulence parameters. Over 100 vertical profiles (mostly over the ocean) with a total of over 300 km in vertical airspace sampled are used. The compiled statistics show that anisotropy in the velocity fluctuations prevail down to the smallest spatial separations measured. A partitioning of convective versus dynamical instability indicates that in the free troposphere, the ratio of shear-produced turbulence to convectively produced turbulence increases from roughly 2:1 for weak turbulence (ϵ 10⁻⁴ m² s⁻³). For the boundary layer, this ratio is close to 1:1 for weak turbulence and roughly 2:1 for strong turbulence. There is also a correlation between the strength of the vertical shear in horizontal winds and the turbulence intensity. In the free troposphere the turbulence intensity is independent of the degree of static stability, whereas in the boundary layer the turbulence intensity increases with a fall in static stability. Vertical humidity gradients correlate with static stability for strong humidity gradients, which supports the basic notion that stable layers impede vertical mixing of trace gases and aerosols. Vertical shear correlates with vertical humidity gradient, so it appears that the effect of differential advection creating tracer gradients dominates the effect of differential advection destroying tracer gradients through shear-induced turbulence.United States. National Aeronautics and Space Administration (Grant NCC1-415)United States. National Aeronautics and Space Administration (Grant NAG1-2306

Intraaortic balloon pumping for cardiac support: Trends in practice and outcome, 1968 to 1995

AbstractObjectives: A total of 4756 cases of intraaortic balloon pump support have been recorded at the Massachusetts General Hospital since the first clinical insertion for cardiogenic shock in 1968. This report describes the patterns of intraaortic balloon use and associated outcomes over this time period.Methods: A retrospective record review was conducted.Results: Balloon use has increased to more than 300 cases a year at present. The practice of balloon placement for control of ischemia (2453 cases, 11.9% mortality) has become more frequent, whereas support for hemodynamic decompensation (congestive heart failure, hypotension, cardiogenic shock) has been relatively constant (1760 cases, 38.2% mortality). Mean patient age has increased from 54 to 66 years, and mortality has fallen from 41% to 20%. Sixty-five percent (3097/4756) of the total patient population receiving balloon support underwent cardiac surgery. Placement before the operation (2038 patients) was associated with a lower mortality (13.6%) than intraoperative (771 patients, 35.7% mortality) or postoperative use (276 patients, 35.9% mortality). Independent predictors of death with balloon pump support were insertion in the operating room or intensive care unit, transthoracic insertion, age, procedure other than angioplasty or coronary artery bypass, and insertion for cardiogenic shock. Independent predictors of death with intraoperative balloon insertion were age, mitral valve replacement, prolonged cardiopulmonary bypass, urgent or emergency operation, preoperative renal dysfunction, complex ventricular ectopy, right ventricular failure, and emergency reinstitution of cardiopulmonary bypass.Conclusions: Balloons are being used more frequently for control of ischemia in more patients who are elderly with lower mortality. An institutional bias toward preoperative use of the balloon pump appears to be associated with improved outcomes. (J Thorac Cardiovasc Surg 1997;113:758-69

1852-02-28 Treaty of Peace Among the Passamaquoddy Tribe

https://digitalmaine.com/native_tribal_docs/1061/thumbnail.jp

Tumor Necrosis Factor Polymorphism Affects Transplantation Outcome in Patients with Myelodysplastic Syndrome but Not in Those with Chronic Myelogenous Leukemia, Independent of the Presence of HLA-DR15

Both the presence of HLA-DR15 and tumor necrosis factor (TNF)-α levels have been reported to affect outcome after hematopoietic cell transplantation (HCT). Patients with a myelodysplastic syndrome (MDS) show a high prevalence of HLA-DR15 and express high levels of TNF-α in the bone marrow. The present analysis involving 7950 patients showed an HLA-DR15 frequency of 31% in patients with MDS, compared with only 23% in patients with chronic myelogenous leukemia (CML). HLA-DR15 was more prevalent in Caucasian patients than in non-Caucasian patients (P = .01). The numbers of patients in the non-Caucasian subgroups were too small to allow further analysis. Among Caucasian patients with MDS and CML, the presence of HLA-DR15 did not significantly affect the occurrence of graft-versus-host disease, relapse, nonrelapse mortality (NRM), or survival. However, there was a significant correlation between DR15 and TNF polymorphisms at position -308 among patients with MDS, and the TNF-308 AG genotype conferred an increased risk of NRM compared with the GG genotype (hazard ratio [HR], 1.49; P = .02), even after adjusting for DR15. Conversely, the TNF-863 AA genotype was correlated with decreased overall mortality and NRM compared with the CC genotype (HR, 0.36, P = .04 vs HR, 0.13, P = .04), even after adjusting for DR15. There was no significant association between TNF-308 or -863 polymorphisms and transplantation outcome in CML patients. These results suggest that TNF polymorphisms, but not DR15, affect transplantation outcome in a disease-dependent manner

Experimental Approach to the Estimation of Short-Run Price-Consumption Relationships for Eggs

The Oklahoma Agricultural Experiment Station periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

The fairness, predictive validity and acceptability of multiple mini interview in an internationally diverse student population--a mixed methods study

BACKGROUND: International medical students, those attending medical school outside of their country of citizenship, account for a growing proportion of medical undergraduates worldwide. This study aimed to establish the fairness, predictive validity and acceptability of Multiple Mini Interview (MMI) in an internationally diverse student population. METHODS: This was an explanatory sequential, mixed methods study. All students in First Year Medicine, National University of Ireland Galway 2012 were eligible to sit a previously validated 10 station MMI. Quantitative data comprised: demographics, selection tool scores and First Year Assessment scores. Qualitative data comprised separate focus groups with MMI Assessors, EU and Non-EU students. RESULTS: 109 students participated (45% of class). Of this 41.3% (n = 45) were Non-EU and 35.8% (n = 39) did not have English as first language. Age, gender and socioeconomic class did not impact on MMI scores. Non-EU students and those for whom English was not a first language achieved significantly lower scores on MMI than their EU and English speaking counterparts (difference in mean 11.9% and 12.2% respectively, P<0.001). MMI score was associated with English language proficiency (IELTS) (r = 0.5, P<0.01). Correlations emerged between First Year results and IELTS (r = 0.44; p = 0.006; n = 38) and EU school exit exam (r = 0.52; p<0.001; n = 56). MMI predicted EU student OSCE performance (r = 0.27; p = 0.03; n = 64). In the analysis of focus group data two overarching themes emerged: Authenticity and Cultural Awareness. MMI was considered a highly authentic assessment that offered a deeper understanding of the applicant than traditional tools, with an immediate relevance to clinical practice. Cultural specificity of some stations and English language proficiency were seen to disadvantage international students. Recommendations included cultural awareness training for MMI assessors, designing and piloting culturally neutral stations, lengthening station duration and providing high quality advance information to candidates. CONCLUSION: MMI is a welcome addition to assessment armamentarium for selection, particularly with regard to stakeholder acceptability. Understanding the mediating and moderating influences for differences in performance of international candidates is essential to ensure that MMI complies with the metrics of good assessment practice and principles of both distributive and procedural justice for all applicants, irrespective of nationality and cultural background

An Absolute Flux Density Measurement of the Supernova Remnant Casseopia A at 32 GHz

We report 32 GHz absolute flux density measurements of the supernova remnant Cas A, with an accuracy of 2.5%. The measurements were made with the 1.5-meter telescope at the Owens Valley Radio Observatory. The antenna gain had been measured by NIST in May 1990 to be $0.505 \pm 0.007 \frac{{\rm mK}}{{\rm Jy}}$. Our observations of Cas A in May 1998 yield $S_{cas,1998} = 194 \pm 5 {\rm Jy}$. We also report absolute flux density measurements of 3C48, 3C147, 3C286, Jupiter, Saturn and Mars.Comment: 30 pages, 4 figures; accepted for publication by AJ. Revised systematic error budget, corrected typos, and added reference