425 research outputs found
The determination of alkali metals, particularly in silicates
The commoner alkali metals, sodium, potassium and lithium, exhibit a strong family resemblance in most properties, both chemical and physical. When it is considered that this resemblance includes their relative solubilities (with some notable exceptions), so that quantitative separation is rendered very difficult, it will be granted that there is ample scope for an investigation dealing solely with the determination of these metals
Data Science at USNA
Data Science is increasingly important to the Navy and Marine Corps. We survey some of the ways that civilian institutions are delivering Data Science curriculum, outline a vision for developing Data Science curriculum at the United States Naval Academy (USNA), and summarize some of the accomplishments and planned activities of the Data Science group at USNA
Independent Orbiter Assessment: Assessment of the FMEA/CIL Instructions and Ground Rules
The McDonnell Douglas Astronautics Company was selected to conduct an independent assessment of the Orbiter Failure Mode and Effects Analysis/Critical Items List (FMEA/CIL). Part of this effort involved an examination of the FMEA/CIL preparation instructions and ground rules. Assessment objectives were to identify omissions and ambiguities in the ground rules that may impede the identification of shuttle orbiter safety and mission critical items, and to ensure that ground rules allow these items to receive proper management visibility for risk assessment. Assessment objectives were followed during the performance of the assessment without being influenced by external considerations such as effects on budget, schedule, and documentation growth. Assessment personnel were employed who had a strong reliability background but no previous space shuttle FMEA/CIL experience to ensure an independent assessment would be achieved. The following observations were made: (1) not all essential items are in the CIL for management visibility; (2) ground rules omit FMEA/CIL coverage of items that perform critical functions; (3) essential items excluded from the CIL do not receive design justification; and (4) FMEAs/CILs are not updated in a timely manner. In addition to the above issues, a number of other issues were identified that correct FMEA/CIL preparation instruction omissions and clarify ambiguities. The assessment was successful in that many of the issues have significant safety implications
Geometric aspects of the Jacobian of a hyperplane arrangement
An embedding of the complete bipartite graph in
gives rise to both a line arrangement and a bar-and-joint framework. For a
generic placement of the six vertices, the graded Betti numbers of the
logarithmic module of derivations of the line arrangement are constant, but an
example due to Ziegler shows that the graded Betti numbers are different when
the points lie on a conic.
Similarly, in rigidity theory a generic embedding of in the plane
is an infinitesimally rigid bar-and-joint framework, but the framework is
infinitesimally flexible when the points lie on a conic. In this paper we
develop the theory of weak perspective representations of hyperplane
arrangements to formalize and generalize the striking connection between
hyperplane arrangements and rigidity theory that this example suggests. In
particular, we seek to understand how the interplay of combinatorics and
geometry influence algebraic structures associated to an arrangement, such as
the saturation of the Jacobian ideal of the arrangement. We make connections
between examples and constructions from rigidity theory and interesting
phenomena in the study of hyperplane arrangements.Comment: 34 pages, 11 figures. Changes made primarily to expositio
Efficacy of PD-1 checkpoint inhibitor therapy in melanoma and beyond: are peripheral T cell phenotypes the key?
Immunotherapy treatment strategies have proven effective in a limited portion of patients, where identifying responders from non-responders to treatment remains a challenge. While some indications can be drawn from invasive biopsies, we need more accessible methods for predicting response and better correlates of response prior to starting therapy. Recent work has identified differences in immune composition at baseline in peripheral blood from melanoma patients responding to PD-1 blockade treatment. Through flow cytometric analysis of T cell receptors, phenotypical features of CD8+ and CD4+ T cells and Tregs could allow for the stratification of treatment response. Analysing T cells within peripheral blood could potentially allow for the stratification of PD-1 treatment response prior to therapy in different cancer settings
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