3,315 research outputs found
Sun-Like Magnetic Cycles in the Rapidly-Rotating Young Solar Analog HD 30495
A growing body of evidence suggests that multiple dynamo mechanisms can drive
magnetic variability on different timescales, not only in the Sun but also in
other stars. Many solar activity proxies exhibit a quasi-biennial (2
year) variation, which is superimposed upon the dominant 11 year cycle. A
well-characterized stellar sample suggests at least two different relationships
between rotation period and cycle period, with some stars exhibiting long and
short cycles simultaneously. Within this sample, the solar cycle periods are
typical of a more rapidly rotating star, implying that the Sun might be in a
transitional state or that it has an unusual evolutionary history. In this
work, we present new and archival observations of dual magnetic cycles in the
young solar analog HD 30495, an 1 Gyr-old G1.5V star with a rotation
period near 11 days. This star falls squarely on the relationships established
by the broader stellar sample, with short-period variations at 1.7 years
and a long cycle of 12 years. We measure three individual long-period
cycles and find durations ranging from 9.6-15.5 years. We find the short-term
variability to be intermittent, but present throughout the majority of the time
series, though its occurrence and amplitude are uncorrelated with the longer
cycle. These essentially solar-like variations occur in a Sun-like star with
more rapid rotation, though surface differential rotation measurements leave
open the possibility of a solar equivalence.Comment: 12 pages, 6 figures. Submitted to Ap
Adolescent smoking networks: The effects of influence and selection on future smoking
Submitted in fulfillment of KU faculty's Open Access Policy.Peer influence and peer selection have both been linked to the smoking behavior of adolescents. The present investigation uses social network analysis methodology to explore the simultaneous effects of both processes on adolescent smoking and smoking susceptibility over two time periods. Results suggest the effects of friendship selection in 6th grade on smoking behavior in 7th grade were primarily direct. Selecting smokers as friends in 6th
grade predicted both smoking and smoking susceptibility in 7th grade, and selecting susceptibles predicted future friendship selection and peer influence. Influence processes were indirectly related to smoking. Smokers' influence
in 6th grade predicts the selection of smokers as friends in 7th grade. Smokers' influence also demonstrated a protective effect when ties were not reciprocated
The Sun-like activity of the solar twin 18 Scorpii
We present the results of 10 yr of complementary spectroscopic and
photometric observations of the solar twin 18 Scorpii. We show that over the
course of its ~7 year chromospheric activity cycle, 18 Sco's brightness varies
in the same manner as the Sun's and with a likely brightness variation of
0.09%, similar to the 0.1% decadal variation in the total solar irradiance
Examining the Conceptual Design Process for Future Hybrid-Electric Rotorcraft
Hybrid-electric propulsion systems introduce immense complexity and numerous design challenges not previously encountered in aircraft design. Traditional conceptual-level rotorcraft design approaches may not adequately capture the level of propulsion system detail desired for hybrid-electric vehicle conceptual design. As part of a NASA Small Business Innovative Research (SBIR) Phase II contract, Empirical Systems Aerospace (ESAero) investigated the implementation of several hybrid-electric propulsion architectures onto three rotorcraft configurations. Unique hybrid-electric variants of these configurations were compared against their conventionally-powered counterparts using typical metrics such as payload, range, and energy efficiency. The feasibility and performance of these vehicles was also investigated in the +15 and +30-year timeframes based on third-party estimations for future component performance. Using the lessons learned during this trade study, ESAero then conducted a conceptual design effort for a hybrid-electric tiltrotor demonstrator based on the XV-15. A detailed integration of the hybrid-electric propulsion system into the vehicle airframe was also performed. The hybrid-electric XV-15 concept vehicle was estimated to achieve a 10% reduction in cruise fuel consumption compared to the original NASA XV-15 at the cost of increasing the vehicle empty weight by almost 25%. The success of this design effort suggests that the design of a manned, hybrid-electric tiltrotor is technically feasible at current technology levels
Identification of Single Nucleotide Polymorphisms Associated with Hyperproduction of Alpha-Toxin in Staphylococcus aureus
The virulence factor α-toxin (hla) is needed by Staphylococcus aureus in order to cause infections in both animals and humans. Although the complicated regulation of hla expression has been well studied in human S. aureus isolates, the mechanisms of of hla regulation in bovine S. aureus isolates remain undefined. In this study, we found that many bovine S. aureus isolates, including the RF122 strain, generate dramatic amounts of α-toxin in vitro compared with human clinical S. aureus isolates, including MRSA WCUH29 and MRSA USA300. To elucidate potential regulatory mechanisms, we analyzed the hla promoter regions and identified predominant single nucleotide polymorphisms (SNPs) at positions −376, −483, and −484 from the start codon in α-toxin hyper-producing isolates. Using site-directed mutagenesis and hla promoter-gfp-luxABCDE dual reporter approaches, we demonstrated that the SNPs contribute to the differential control of hla expression among bovine and human S. aureus isolates. Using a DNA affinity assay, gel-shift assays and a null mutant, we identified and revealed that an hla positive regulator, SarZ, contributes to the involvement of the SNPs in mediating hla expression. In addition, we found that the bovine S. aureus isolate RF122 exhibits higher transcription levels of hla positive regulators, including agrA, saeR, arlR and sarZ, but a lower expression level of hla repressor rot compared to the human S. aureus isolate WCUH29. Our results indicate α-toxin hyperproduction in bovine S. aureus is a multifactorial process, influenced at both the genomic and transcriptional levels. Moreover, the identification of predominant SNPs in the hla promoter region may provide a novel method for genotyping the S. aureus isolates
The Activity and Variability of the Sun and Sun-Like Stars. II. Contemporaneous Photometry and Spectroscopy of Bright Solar Analogs
We present 14 years of contemporaneous photometric and spectroscopic observations of 28 solar analog stars, taken with the Tennessee State University Automatic Photometric Telescopes at Fairborn Observatory and the Solar-Stellar Spectrograph at Lowell Observatory. These are the best observed and most nearly Sun-like of the targets in our magnitude-limited (V ⩽  7.5) sample. The correlations between luminosity and activity reveal the expected inverse activity–brightness correlations for active stars. Strong direct correlations between activity and brightness are not prevalent for the less active solar age stars, but are precision limited. The Sun does not appear to have unusually low photometric variability when compared with the most Sun-like inactive solar analogs. We present evidence that the activity index R\u27HK is not a good discriminant of Maunder Minimum candidate stars. On the basis of a star that appears to have transitioned from a low-variability state to a cycling state, we investigate the regime in which stars might switch from faculae-dominated to spot-dominated variations
Intellectual Property and Public Health – A White Paper
On October 26, 2012, the University of Akron School of Law’s Center for Intellectual Property and Technology hosted its Sixth Annual IP Scholars Forum. In attendance were thirteen legal scholars with expertise and an interest in IP and public health who met to discuss problems and potential solutions at the intersection of these fields. This report summarizes this discussion by describing the problems raised, areas of agreement and disagreement between the participants, suggestions and solutions made by participants and the subsequent evaluations of these suggestions and solutions. Led by the moderator, participants at the Forum focused generally on three broad questions. First, are there alternatives to either the patent system or specific patent doctrines that can provide or help provide sufficient incentives for health-related innovation? Second, is health information being used proprietarily and if so, is this type of protection appropriate? Third, does IP conflict with other non-IP values that are important in health and how does or can IP law help resolve these conflicts? This report addresses each of these questions in turn
Description and Status of the North Alabama Lightning Mapping Array
The North Alabama Lightning Mapping Array (LMA) is a network LMA detectors that detects and maps lightning using VHF radiation (TV Channel 5) in a region centered about Huntsville, Alabama that includes North Alabama, Central Tennessee and parts of Georgia and Mississippi. The North Alabama LMA has been in operation since late 2001, and has been providing real time data to regional National Weather Service (NSF) Weather Forecast Offices (WFOs) since mid 2003 through the NASA Short-term Prediction Research and Transition (SPoRT) center. Data from this network (as well as other from other LMA systems) are now being used to create proxy Geostationary Lightning Mapper (GLM) data sets for GOES-R risk reduction and algorithm development activities. In addition, since spring 2009 data are provided to the Storm Prediction Center in support of Hazardous Weather Testbed and GOES-R Proving Ground activities during the Spring Program. Description, status and plans will be discussed
Measuring the learning effectiveness of serious gaming for training of complex manufacturing tasks
© 2017, © The Author(s) 2017. Background. Training new workers on complex manufacturing tasks has long been a challenge for high value manufacturing companies. Equipment downtime, costly instructors, and dangerous working environments are some of the impediments of hands-on training. To overcome these hurdles, a traditional manufacturing paper manual was transformed into a serious game through capturing and embedding expert knowledge. Aim. This article investigates the learning effectiveness of learning via a serious game (Training Game) compared with the tradition learning method (Paper Manual) through a user study. Method. Twenty employees took part in a randomised controlled trial. They were assigned to one of two conditions: Training Game (experimental condition), or Paper Manual (control condition). Participants spent a maximum of 30 minutes to study manufacturing instructions before completing two tests to evaluate the amount of learning achieved. Results. The results show that the Training Game was more effective for learning procedu ral knowledge than the Paper Manual. Regarding factual knowledge, no significant difference was identified between the two conditions. In terms of motivation, increased engagement levels were reported in the Training Game condition. Conclusions. This user study shows evidence that the serious TG being evaluated is an effective method for training procedural knowledge in a complex manufacturing scenario
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