14,471 research outputs found
Performance of the CMS Level-1 Trigger
The first level trigger of the CMS experiment is comprised of custom
electronics that process data from the electromagnetic and hadron calorimeters
and three technologies of muon detectors in order to select the most
interesting events from LHC collisions, such as those consistent with the
production and decay of the Higgs boson. The rate of events selected by this
Level-1 trigger must be reduced from the beam crossing frequency to no more
than 100 kHz further processing can occur, a major challenge since the LHC
instantaneous luminosity has increased by six orders of magnitude since the
start of operations to more than 6E33 cm-2s-1 today. The performance of the
Level-1 trigger, in terms of rates and efficiencies of the main objects and
trigger algorithms, as measured from LHC proton collisions at 7 and 8 TeV
center-of-mass energies is presented here.Comment: Presented at 36th International Conference on High Energy Physics,
July 4-11, 2012, Melbourne, Australi
Century scale persistence in longitude distribution: in the Sun and in silico
Using Greenwich sunspot data for 120 years it was recently observed that
activity regions on the Sun's surface tend to lie along smoothly changing
longitude strips 180 degrees apart from each other. However, numerical
experiments with random input data show that most, if not all, of the observed
longitude discrimination can be looked upon as an artifact of the analysis
method.Comment: 4 pages, 12 figures, accepted for publication in Astronomy and
Astrophysic
The Value of User-Visible Internet Cryptography
Cryptographic mechanisms are used in a wide range of applications, including
email clients, web browsers, document and asset management systems, where
typical users are not cryptography experts. A number of empirical studies have
demonstrated that explicit, user-visible cryptographic mechanisms are not
widely used by non-expert users, and as a result arguments have been made that
cryptographic mechanisms need to be better hidden or embedded in end-user
processes and tools. Other mechanisms, such as HTTPS, have cryptography
built-in and only become visible to the user when a dialogue appears due to a
(potential) problem. This paper surveys deployed and potential technologies in
use, examines the social and legal context of broad classes of users, and from
there, assesses the value and issues for those users
Hellinger Distance Trees for Imbalanced Streams
Classifiers trained on data sets possessing an imbalanced class distribution
are known to exhibit poor generalisation performance. This is known as the
imbalanced learning problem. The problem becomes particularly acute when we
consider incremental classifiers operating on imbalanced data streams,
especially when the learning objective is rare class identification. As
accuracy may provide a misleading impression of performance on imbalanced data,
existing stream classifiers based on accuracy can suffer poor minority class
performance on imbalanced streams, with the result being low minority class
recall rates. In this paper we address this deficiency by proposing the use of
the Hellinger distance measure, as a very fast decision tree split criterion.
We demonstrate that by using Hellinger a statistically significant improvement
in recall rates on imbalanced data streams can be achieved, with an acceptable
increase in the false positive rate.Comment: 6 Pages, 2 figures, to be published in Proceedings 22nd International
Conference on Pattern Recognition (ICPR) 201
Explicit constructions of infinite families of MSTD sets
We explicitly construct infinite families of MSTD (more sums than
differences) sets. There are enough of these sets to prove that there exists a
constant C such that at least C / r^4 of the 2^r subsets of {1,...,r} are MSTD
sets; thus our family is significantly denser than previous constructions
(whose densities are at most f(r)/2^{r/2} for some polynomial f(r)). We
conclude by generalizing our method to compare linear forms epsilon_1 A + ... +
epsilon_n A with epsilon_i in {-1,1}.Comment: Version 2: 14 pages, 1 figure. Includes extensions to ternary forms
and a conjecture for general combinations of the form Sum_i epsilon_i A with
epsilon_i in {-1,1} (would be a theorem if we could find a set to start the
induction in general
Curriculum Innovation: Incorporating the Kern Engineering Entrepreneurial Network (KEEN) Framework into Online Discussions
The purpose of this study was to respond to the following research question: How does the Kern Engineering Entrepreneurial Network (KEEN) framework build interest in technical topic areas, impact student learning outcomes, and develop the entrepreneurial mindset when applied to the engineering classroom? The KEEN framework was developed to combine the entrepreneurial mindset with engineering education to produce a more valuable, strategically prepared engineer, rather than simply an âobedient engineerâ. The framework proposes that the entrepreneurial mindset of students is increased by promoting curiosity, encouraging connections, and creating value. The results from this work provide insight into the impact and implications resulting from applying the KEEN framework to the engineering classroom via online discussions
Comparing Wearer DNA Sample Collection Methods for the Recovery of Single Source Profiles
Wearer DNA is the deposit of epithelial cells on clothing worn by an individual. Detection of the last individual to handle or wear an item is often an important and desirable determination in forensic science. The most commonly used collection methods for wearer DNA include swabbing and scraping. These often result in mixture profiles. Recently, adhesives have been introduced as a possible reliable method for the collection of biological evidence. The goal of the research was to compare the current collection methods of swabbing and scraping with a gel film called Gel-Pak â0â which shares similar properties with adhesives. Gel-Pak â0â has been previously studied in comparison to other adhesives for the collection of epithelial cells, and was shown to recover the top layer of loose particulate. This particulate had a tendency to be deposited by the individual who last came in contact with an item. Therefore, in comparison to the other two collection methods, Gel-Pak â0â was
hypothesized to recover single source profiles on clothing items from the most recent wearer. DNA analysis was performed on samples collected by the three methods from various clothing items including baseball hats, t-shirts, sweatpants, socks, and other items commonly submitted to crime labs for DNA analysis. The habitual wearer and the second/last wearer wore each item for a predetermined amount of time. The results of the research showed that Gel-Pak â0â recovered a similar number of CODIS (local and national) eligible profiles as swabbing. However, coupled with the fact that it is time consuming, costly, and cannot be used on all surfaces, Gel-Pak â0â was determined to not make for an effective collection method of the most recent wearerâs DNA. Therefore, Gel-Pak â0â will not be considered for casework. Although Gel-Pak â0â will not be further used, the results did reveal some trends that may shed light on how DNA analysts may approach wearer DNA cases. Swabbing had a tendency to yield smaller amounts of DNA in comparison to scraping, but obtain DNA from the last wearer of the piece of clothing more effectively than the other two methods. Scraping had a tendency to yield greater quantities of DNA, recovering more DNA from the habitual wearer due to its invasive nature. Revealing individuals who last wore an item can be of great importance in forensic science, and therefore, further research with various adhesives and gel films could be vital for solving forensic investigations
Pulsed laser deposition growth of Fe3O4 on IIIâV semiconductors for spin injection
We report on the growth of thin layers of Fe3O4 on GaAs and InAs by pulsed laser deposition. It is found that Fe3O4 grows epitaxially on InAs at a temperature of 350 °C. X-ray photoelecton spectroscopy (XPS) studies of the interface show little if any interface reaction resulting in a clean epitaxial interface. In contrast, Fe3O4 grows in columnar fashion on GaAs, oriented with respect to the growth direction but with random orientation in the plane of the substrate. In this case XPS analysis showed much more evidence of interface reactions, which may contribute to the random-in-plane growth
Squeezed states: A geometric framework
A general definition of squeezed states is proposed and its main features are illustrated through a discussion of the standard optical coherent states represented by 'Gaussian pure states'. The set-up involves representations of groups on Hilbert spaces over homogeneous spaces of the group, and relies on the construction of a square integrable (coherent state) group representation modulo a subgroup. This construction depends upon a choice of a Borel section which has a certain permissible arbitrariness in its selection; this freedom is attributable to a squeezing of the defining coherent states of the representation, and corresponds in this way to a sort of gauging
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