3,716 research outputs found
A Survey of Local Group Galaxies Currently Forming Stars. I. UBVRI Photometry of Stars in M31 and M33
We present UBVRI photometry obtained from Mosaic images of M31 and M33 using
the KPNO 4-m telescope. The survey covers 2.2 sq degrees of M31, and 0.8 sq
degrees of M33, chosen so as to include all of the regions currently active in
forming massive stars. The catalog contains 371,781 and 146,622 stars in M31
and M33, respectively, where every star has a counterpart (at least) in B, V,
and R. We compare our photometry to previous studies. We provide cross
references to the stars confirmed as members by spectroscopy, and compare the
location of these to the complete set in color-magnitude diagrams. While
follow-up spectroscopy is needed for many projects, we demonstrate the success
of our photometry in being able to distinguish M31/M33 members from foreground
Galactic stars. We also present the results of newly obtained spectroscopy,
which identifies 34 newly confirmed members, including B-A supergiants, the
earliest O star known in M31, and two new Luminous Blue Variable candidates
whose spectra are similar to that of P Cygni.Comment: Accepted by the Astronomical Journal. A version with higher
resolution figures can be found at:
http://www.lowell.edu/users/massey/M3133.pdf.g
Engineering Resilient Space Systems
Several distinct trends will influence space exploration missions in the next decade. Destinations are
becoming more remote and mysterious, science questions more sophisticated, and, as mission experience
accumulates, the most accessible targets are visited, advancing the knowledge frontier to more difficult,
harsh, and inaccessible environments. This leads to new challenges including: hazardous conditions that
limit mission lifetime, such as high radiation levels surrounding interesting destinations like Europa or
toxic atmospheres of planetary bodies like Venus; unconstrained environments with navigation hazards,
such as free-floating active small bodies; multielement missions required to answer more sophisticated
questions, such as Mars Sample Return (MSR); and long-range missions, such as Kuiper belt exploration,
that must survive equipment failures over the span of decades. These missions will need to be successful
without a priori knowledge of the most efficient data collection techniques for optimum science return.
Science objectives will have to be revised ‘on the fly’, with new data collection and navigation decisions
on short timescales.
Yet, even as science objectives are becoming more ambitious, several critical resources remain
unchanged. Since physics imposes insurmountable light-time delays, anticipated improvements to the
Deep Space Network (DSN) will only marginally improve the bandwidth and communications cadence to
remote spacecraft. Fiscal resources are increasingly limited, resulting in fewer flagship missions, smaller
spacecraft, and less subsystem redundancy. As missions visit more distant and formidable locations, the
job of the operations team becomes more challenging, seemingly inconsistent with the trend of shrinking
mission budgets for operations support. How can we continue to explore challenging new locations
without increasing risk or system complexity?
These challenges are present, to some degree, for the entire Decadal Survey mission portfolio, as
documented in Vision and Voyages for Planetary Science in the Decade 2013–2022 (National Research
Council, 2011), but are especially acute for the following mission examples, identified in our recently
completed KISS Engineering Resilient Space Systems (ERSS) study:
1. A Venus lander, designed to sample the atmosphere and surface of Venus, would have to perform
science operations as components and subsystems degrade and fail;
2. A Trojan asteroid tour spacecraft would spend significant time cruising to its ultimate destination
(essentially hibernating to save on operations costs), then upon arrival, would have to act as its
own surveyor, finding new objects and targets of opportunity as it approaches each asteroid,
requiring response on short notice; and
3. A MSR campaign would not only be required to perform fast reconnaissance over long distances
on the surface of Mars, interact with an unknown physical surface, and handle degradations and
faults, but would also contain multiple components (launch vehicle, cruise stage, entry and
landing vehicle, surface rover, ascent vehicle, orbiting cache, and Earth return vehicle) that
dramatically increase the need for resilience to failure across the complex system.
The concept of resilience and its relevance and application in various domains was a focus during the
study, with several definitions of resilience proposed and discussed. While there was substantial variation
in the specifics, there was a common conceptual core that emerged—adaptation in the presence of
changing circumstances. These changes were couched in various ways—anomalies, disruptions,
discoveries—but they all ultimately had to do with changes in underlying assumptions. Invalid
assumptions, whether due to unexpected changes in the environment, or an inadequate understanding of
interactions within the system, may cause unexpected or unintended system behavior. A system is
resilient if it continues to perform the intended functions in the presence of invalid assumptions.
Our study focused on areas of resilience that we felt needed additional exploration and integration,
namely system and software architectures and capabilities, and autonomy technologies. (While also an
important consideration, resilience in hardware is being addressed in multiple other venues, including
2
other KISS studies.) The study consisted of two workshops, separated by a seven-month focused study
period. The first workshop (Workshop #1) explored the ‘problem space’ as an organizing theme, and the
second workshop (Workshop #2) explored the ‘solution space’. In each workshop, focused discussions
and exercises were interspersed with presentations from participants and invited speakers.
The study period between the two workshops was organized as part of the synthesis activity during the
first workshop. The study participants, after spending the initial days of the first workshop discussing the
nature of resilience and its impact on future science missions, decided to split into three focus groups,
each with a particular thrust, to explore specific ideas further and develop material needed for the second
workshop. The three focus groups and areas of exploration were:
1. Reference missions: address/refine the resilience needs by exploring a set of reference missions
2. Capability survey: collect, document, and assess current efforts to develop capabilities and
technology that could be used to address the documented needs, both inside and outside NASA
3. Architecture: analyze the impact of architecture on system resilience, and provide principles and
guidance for architecting greater resilience in our future systems
The key product of the second workshop was a set of capability roadmaps pertaining to the three
reference missions selected for their representative coverage of the types of space missions envisioned for
the future. From these three roadmaps, we have extracted several common capability patterns that would
be appropriate targets for near-term technical development: one focused on graceful degradation of
system functionality, a second focused on data understanding for science and engineering applications,
and a third focused on hazard avoidance and environmental uncertainty. Continuing work is extending
these roadmaps to identify candidate enablers of the capabilities from the following three categories:
architecture solutions, technology solutions, and process solutions.
The KISS study allowed a collection of diverse and engaged engineers, researchers, and scientists to think
deeply about the theory, approaches, and technical issues involved in developing and applying resilience
capabilities. The conclusions summarize the varied and disparate discussions that occurred during the
study, and include new insights about the nature of the challenge and potential solutions:
1. There is a clear and definitive need for more resilient space systems. During our study period,
the key scientists/engineers we engaged to understand potential future missions confirmed the
scientific and risk reduction value of greater resilience in the systems used to perform these
missions.
2. Resilience can be quantified in measurable terms—project cost, mission risk, and quality of
science return. In order to consider resilience properly in the set of engineering trades performed
during the design, integration, and operation of space systems, the benefits and costs of resilience
need to be quantified. We believe, based on the work done during the study, that appropriate
metrics to measure resilience must relate to risk, cost, and science quality/opportunity. Additional
work is required to explicitly tie design decisions to these first-order concerns.
3. There are many existing basic technologies that can be applied to engineering resilient space
systems. Through the discussions during the study, we found many varied approaches and
research that address the various facets of resilience, some within NASA, and many more
beyond. Examples from civil architecture, Department of Defense (DoD) / Defense Advanced
Research Projects Agency (DARPA) initiatives, ‘smart’ power grid control, cyber-physical
systems, software architecture, and application of formal verification methods for software were
identified and discussed. The variety and scope of related efforts is encouraging and presents
many opportunities for collaboration and development, and we expect many collaborative
proposals and joint research as a result of the study.
4. Use of principled architectural approaches is key to managing complexity and integrating
disparate technologies. The main challenge inherent in considering highly resilient space
systems is that the increase in capability can result in an increase in complexity with all of the
3
risks and costs associated with more complex systems. What is needed is a better way of
conceiving space systems that enables incorporation of capabilities without increasing
complexity. We believe principled architecting approaches provide the needed means to convey a
unified understanding of the system to primary stakeholders, thereby controlling complexity in
the conception and development of resilient systems, and enabling the integration of disparate
approaches and technologies. A representative architectural example is included in Appendix F.
5. Developing trusted resilience capabilities will require a diverse yet strategically directed
research program. Despite the interest in, and benefits of, deploying resilience space systems, to
date, there has been a notable lack of meaningful demonstrated progress in systems capable of
working in hazardous uncertain situations. The roadmaps completed during the study, and
documented in this report, provide the basis for a real funded plan that considers the required
fundamental work and evolution of needed capabilities.
Exploring space is a challenging and difficult endeavor. Future space missions will require more
resilience in order to perform the desired science in new environments under constraints of development
and operations cost, acceptable risk, and communications delays. Development of space systems with
resilient capabilities has the potential to expand the limits of possibility, revolutionizing space science by
enabling as yet unforeseen missions and breakthrough science observations.
Our KISS study provided an essential venue for the consideration of these challenges and goals.
Additional work and future steps are needed to realize the potential of resilient systems—this study
provided the necessary catalyst to begin this process
Santa Clara Magazine, Volume 39 Number 1, Spring 1997
6 - BLUE SKY INVASION Searching for the American Dream, aerospace workers transform the Santa Clara Valley. By David Beers \u2779, Illustrations by Dug Waggoner
15 - SEEING IS BELIEVING Professor Sally Wood develops software to help students visualize basic engineering concepts. By Laura Trujillo \u2792
18 - CONFRONTING THE SCARS OF CENTURIES A legal challenge to California\u27s Proposition 209 is the latest round in a long- running debate over affirmative action. By Margaret M. Russell
26 - SHADOWY ALLIANCE A recent expose alleging CIA links to the crack cocaine epidemic in California\u27s inner cities raises questions about responsibility and truth in journalism. By Peter Kornbluhhttps://scholarcommons.scu.edu/sc_mag/1063/thumbnail.jp
The Physics of the Accelerating Universe Survey: narrow-band image photometry
PAUCam is an innovative optical narrow-band imager mounted at the William Herschel Telescope built for the Physics of the Accelerating Universe Survey (PAUS). Its set of 40 filters results in images that are complex to calibrate, with specific instrumental signatures that cannot be processed with traditional data reduction techniques. In this paper, we present two pipelines developed by the PAUS data management team with the objective of producing science-ready catalogues from the uncalibrated raw images. The NIGHTLY pipeline takes care of entire image processing, with bespoke algorithms for photometric calibration and scatter-light correction. The Multi-Epoch and Multi-Band Analysis pipeline performs forced photometry over a reference catalogue to optimize the photometric redshift (photo-z) performance. We verify against spectroscopic observations that the current approach delivers an inter-band photometric calibration of 0.8 per cent across the 40 narrow-band set. The large volume of data produced every night and the rapid survey strategy feedback constraints require operating both pipelines in the Port d’Informació Cientifica data centre with intense parallelization. While alternative algorithms for further improvements in photo-z performance are under investigation, the image calibration and photometry presented in this work already enable state-of-the-art photo-z down to iAB = 23.0
SECOND INTERNATIONAL ANTHOLOGY ON P ARADOXISM
"It took me ten years to collect all these texts dealing with the paradoxism, since I came to America, reading more than one thousand envelopes stuffed with manuscripts. They followed me at my address, often changed upon my job, in Phoenix and Tucson (Arizona) or in Gallup (New Mexico). I tried to answer each letter sending information on the paradoxism and also paradoxist diplomas where it was the case. Now I congratulate al/ these 100 writers who contributed to this anthology with poems, prose, dramas, essays, letters. This is an international fan on the dimensions of the paradoxism, twenty years after its setting up.
Auditing Symposium X: Proceedings of the 1990 Deloitte & Touche/University of Kansas Symposium on Auditing Problems
Discussant\u27s response to Analytical procedure results as substantive evidence / Abraham D. Akresh; Assessing control risk: Effects of procedural differences on auditor consensus / Jane E. Morton, William L. Felix; Discussant\u27s response to Assessing control risk: Effects of procedural differences on auditor consensus / Richard W. Kruetzfeldt; Illegal acts: What is the auditor\u27s responsibility? / Dan M. Guy, Ray O. Whittington, Donald L. Neebes; Discussants\u27 response no 1 to Illegal acts: What is the auditor\u27s responsibility? / Tim Damewood, Susan Harshberger, Russ Jones; Discussant\u27s response no 2 to Illegal acts: What is the auditor\u27s responsibility? / Frances M. McNair; Panel discussion on The impact of mergers of accounting firms on the auditing profession / Stephen J. Aldersley, David W. Hunerberg, Jonathan E. Kilner, Julia A. Lelik, Roger R. Nelson; New global realities and their impact on the accounting profession / Edward A. Kangas; Discussant\u27s response to With firmness in the right / Theodore F. Bluey; Neural nets versus logistic regression: A comparison of each model\u27s ability to predict commercial bank failures / Timothy B. Bell, Gary S. Ribar, Jennifer Verichio; Discussant\u27s response to Neural nets versus logistic regression: A comparison of each model\u27s ability to predict commercial bank failures / Miklos A. Vasarhelyi; Expert systems and AI-based decision support in auditing: Progress and perspectives / William E. McCarth, Eric Denna, Graham Gal; Discussant\u27s response to Expert systems and AI-based decision support in auditing: Progress and perspectives / Dana A. Madalon, Frederick W. Rook; Analytical procedure results as substantive evidence / William R. Kinney, Christine M. Hanes; With firmness in the right / Frederick L. Neumannhttps://egrove.olemiss.edu/dl_proceedings/1009/thumbnail.jp
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Entrepreneurial Literary Theory: A Debate on Research and the Future of Academia
Across the world at present, researchers and teachers are being exhorted to become entrepreneurial. Universities are being restructured accordingly. The debate presented in this book considers what that involves and portends for academia. Literary studies are often regarded as the most resistant to – unfit for – entrepreneurial purposes. Literary research is therefore taken as a baseline for this debate. The uneasy place of literary research within profit-driven academia is revealing of the prevailing conditions for scholarship in all areas.
Questions that are raised and discussed here include: What does doing research for the public good mean? What is the relationship between profits and benefits from research? What are applied and basic research? Are concepts of academic freedom and disinterestedness meaningful? What is the relationship between corporate and academic research? Are skills and knowledge different? Can pursuits like close reading and text interpretation be made profitable? What is literary value and how can it be measured? Can the literary system be modelled to profitable ends? Can university teaching be automatized? What are the differences between a standard publication agreement and a scholarly publication agreement? How can digital and open-access academic publication be made profitable? Does the academic monograph have a future? What sorts of knowledge and skills inform entrepreneurial leadership
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