11,389 research outputs found
Regional significance of the Jim River and Hodzana plutons
https://deepblue.lib.umich.edu/bitstream/2027.42/155692/1/Blum_et_al_1989_Regional_significance.pd
The Stellar Content of Obscured Galactic Giant HII Regions. VI: W51A
We present K-band spectra of newly born OB stars in the obscured Galactic
giant H II region W51A and ~ 0.8'' angular resolution images in the J, H and
K_S-bands. Four objects have been spectroscopically classified as O-type stars.
The mean spectroscopic parallax of the four stars gives a distance of 2.0 \pm
0.3 kpc (error in the mean), significantly smaller than the radio recombination
line kinematic value of 5.5 kpc or the values derived from maser propermotion
observations (6--8 kpc). The number of Lyman continuum photons from the
contribution of all massive stars (NLyc ~ 1.5 x 10^{50} s^{-1}) is in good
agreement with that inferred from radio recombination lines (NLyc = 1.3 x
10^{50} s^{-1}) after accounting for the smaller distance derived here.
We present analysis of archival high angular resolution images (NAOS CONICA
at VLT and T-ReCS at Gemini) of the compact region W51 IRS2. The K_S--band
images resolve the infrared source IRS~2 indicating that it is a very young
compact HII region. Sources IRS2E was resolved into compact cluster (within 660
AU of projected distance) of 3 objects, but one of them is just bright extended
emission. W51d1 and W51d2 were identified with compact clusters of 3 objects
(maybe 4 in the case of W51d1) each one. Although IRS~2E is the brightest
source in the K-band and at 12.6 \micron, it is not clearly associated with a
radio continuum source. Our spectrum of IRS~2E shows, similar to previous work,
strong emission in Br and HeI, as well as three forbidden emission
lines of FeIII and emission lines of molecular hydrogen (H_2) marking it as a
massive young stellar object.Comment: 31 pages and 9 figures, submitted to A
Stem clutch for motor driven valve
Development of mechanical device to reduce possibility of damage to motor driven needle valve is discussed. Mechanical clutch is employed to allow slippage when needle valve reaches limit of travel. Operation of system for various conditions is described
A model of mercury cycling and isotopic fractionation in the ocean
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155773/1/Archer_and_Blum_2018_model_of_mercury.pd
Thermal Characterization of PMMA Thin Films on Silica Using Modulated Differential Scanning Calorimetry
The number of studies of thin polymer films has increased over recent years as technological processes incorporate the use of nanomaterials. An enhanced understanding of these films would enable us to predict bound-polymer behavior and thus improve the efficiency of processes and the quality of products. This is especially true as the thickness of the films approach molecular dimensions. The glass transition temperature of a polymer is one of the most important properties for characterization because it indicates how the polymer might perform macroscopically. when a polymer is confined, such as one the surface of a substrate, its behavior is influenced by molecular interactions between the polymer and the substrate. These interactions may affect the polymer\u27s glass transition temperature and warrant scientific investigation. This study uses modulated differential scanning calorimetric (MDSC) to examine the glass transition of poly (methyl methacrylate) adsorbed onto silica. We varied the amount of polymer adsorbed, and found that the Tg center and its breadth increased with decreased coverage. T o our knowledge this is the first reported analysis of such very thin polymer films using MDSC
Strategies To Win: Six-Steps For Creating Problem Statements In Doctoral Research
The problem in a doctoral dissertation is the most critical component of the study. (Creswell, 2004; Simon & Francis, 2004; Sproull, 1995). The problem explains the rationale for the study, validates its importance, and determines the research design. Many students do not know how to write a problem statement despite its importance (Simon & Francis, 2004). Currently no systematic process exists to teach students how to write a problem statement. The problem is compounded for distance education students who do not have face-to-face instructor contact. This article will present a six-step method for teaching online doctoral students how to write a problem statement. The process is used at the University of Phoenix Online School of Advanced Studies (SAS)
Machine Learning and Irresponsible Inference: Morally Assessing the Training Data for Image Recognition Systems
Just as humans can draw conclusions responsibly or irresponsibly, so too can computers. Machine learning systems that have been trained on data sets that include irresponsible judgments are likely to yield irresponsible predictions as outputs. In this paper I focus on a particular kind of inference a computer system might make: identification of the intentions with which a person acted on the basis of photographic evidence. Such inferences are liable to be morally objectionable, because of a way in which they are presumptuous. After elaborating this moral concern, I explore the possibility that carefully procuring the training data for image recognition systems could ensure that the systems avoid the problem. The lesson of this paper extends beyond just the particular case of image recognition systems and the challenge of responsibly identifying a person’s intentions. Reflection on this particular case demonstrates the importance (as well as the difficulty) of evaluating machine learning systems and their training data from the standpoint of moral considerations that are not encompassed by ordinary assessments of predictive accuracy
Provably Secure Experimental Quantum Bit-String Generation
Coin tossing is a cryptographic task in which two parties who do not trust
each other aim to generate a common random bit. Using classical communication
this is impossible, but non trivial coin tossing is possible using quantum
communication. Here we consider the case when the parties do not want to toss a
single coin, but many. This is called bit string generation. We report the
experimental generation of strings of coins which are provably more random than
achievable using classical communication. The experiment is based on the ``plug
and play'' scheme developed for quantum cryptography, and therefore well suited
for long distance quantum communication.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. Lett. A complete security
analysis for the experiment is given in quant-ph/040812
Scaling in Complex Systems: Analytical Theory of Charged Pores
In this paper we find an analytical solution of the equilibrium ion
distribution for a toroidal model of a ionic channel, using the Perfect
Screening Theorem (PST). The ions are charged hard spheres, and are treated
using a variational Mean Spherical Approximation (VMSA) .
Understanding ion channels is still a very open problem, because of the many
exquisite tuning details of real life channels. It is clear that the electric
field plays a major role in the channel behaviour, and for that reason there
has been a lot of work on simple models that are able to provide workable
theories. Recently a number of interesting papers have appeared that discuss
models in which the effect of the geometry, excluded volume and non-linear
behaviour is considered.
We present here a 3D model of ionic channels which consists of a charged,
deformable torus with a circular or elliptical cross section, which can be flat
or vertical (close to a cylinder). Extensive comparisons to MC simulations were
performed.
The new solution opens new possibilities, such as studying flexible pores,
and water phase transformations inside the pores using an approach similar to
that used on flat crystal surfaces
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