1,391 research outputs found
Light Trap Records of \u3ci\u3ePhyllophaga\u3c/i\u3e (Coleoptera: Scarabaeidae) in Wisconsin, 1984-1987
Phyllophaga adults (June beetles) were surveyed from 1984 through 1987 at five locations in Wisconsin using black light traps. Data were collected at each location for three consecutive years. A total of 9,259 specimens representing 13 species were collected during the survey. Species captured, sex ratios, and flight periods for abundant species were recorded for each location. Species abundance differed from previous surveys of Phyllophaga in Wisconsin. Possible reasons for observed shifts in species abundance are discussed
Super-lattice, rhombus, square, and hexagonal standing waves in magnetically driven ferrofluid surface
Standing wave patterns that arise on the surface of ferrofluids by (single
frequency) parametric forcing with an ac magnetic field are investigated
experimentally. Depending on the frequency and amplitude of the forcing, the
system exhibits various patterns including a superlattice and subharmonic
rhombuses as well as conventional harmonic hexagons and subharmonic squares.
The superlattice arises in a bicritical situation where harmonic and
subharmonic modes collide. The rhombic pattern arises due to the non-monotonic
dispersion relation of a ferrofluid
Assessing the Benefits of NASA Category 3, Low Cost Class C/D Missions
Category 3, Class C/D missions have the benefit of delivering worthwhile science at minimal cost which is increasingly important in NASA's constrained budget environment. Although higher cost Category 1 and 2 missions are necessary to achieve NASA's science objectives, Category 3 missions are shown to be an effective way to provide significant science return at a low cost. Category 3 missions, however, are often reviewed the same as the more risk averse Category 1 and 2 missions. Acknowledging that reviews are not the only aspect of a total engineering effort, reviews are still a significant concern for NASA programs. This can unnecessarily increase the cost and schedule of Category 3 missions. This paper quantifies the benefit and performance of Category 3 missions by looking at the cost vs. capability relative to Category 1 and 2 missions. Lessons learned from successful organizations that develop low cost Category 3, Class C/D missions are also investigated to help provide the basis for suggestions to streamline the review of NASA Category 3 missions
Wave Number of Maximal Growth in Viscous Magnetic Fluids of Arbitrary Depth
An analytical method within the frame of linear stability theory is presented
for the normal field instability in magnetic fluids. It allows to calculate the
maximal growth rate and the corresponding wave number for any combination of
thickness and viscosity of the fluid. Applying this method to magnetic fluids
of finite depth, these results are quantitatively compared to the wave number
of the transient pattern observed experimentally after a jump--like increase of
the field. The wave number grows linearly with increasing induction where the
theoretical and the experimental data agree well. Thereby a long-standing
controversy about the behaviour of the wave number above the critical magnetic
field is tackled.Comment: 19 pages, 15 figures, RevTex; revised version with a new figure and
references added. submitted to Phys Rev
Incidence of ANCA-associated vasculitis in a UK mixed ethnicity population
Objectives: We aimed to estimate the incidence of ANCA-associated vasculitis in the UK and how this varied by ethnic group.
Methods: We identified incident cases of ANCA-associated vasculitis between March 2007 and June 2013 in the Nottingham–Derby urban area from medical records using multiple sources. We derived the denominator population from the 2011 census, and we calculated incidence rate ratios using Poisson regression.
Results: Overall, we identified 107 cases of ANCA-associated vasculitis, giving an incidence of 23.1 per million person-years (95% CI: 18.9, 27.9). The incidence among the white population was 25.8 per million person-years (95% CI: 21.0, 31.3) and among the black and minority ethnic (BME) population 8.4 per million person-years (95% CI: 3.1, 18.3). After adjustment for age and sex, the difference between ethnic groups was not statistically significant (incidence rate ratio 0.7, 95% CI: 0.3, 1.5, P = 0.3).
Conclusion: Overall, the incidence of ANCA-associated vasculitis was similar to other epidemiological studies. Crude incidence rates were lower in the BME than in the white population, but this was partly explained by the older age profile among the white compared with BME population
Logics of Finite Hankel Rank
We discuss the Feferman-Vaught Theorem in the setting of abstract model
theory for finite structures. We look at sum-like and product-like binary
operations on finite structures and their Hankel matrices. We show the
connection between Hankel matrices and the Feferman-Vaught Theorem. The largest
logic known to satisfy a Feferman-Vaught Theorem for product-like operations is
CFOL, first order logic with modular counting quantifiers. For sum-like
operations it is CMSOL, the corresponding monadic second order logic. We
discuss whether there are maximal logics satisfying Feferman-Vaught Theorems
for finite structures.Comment: Appeared in YuriFest 2015, held in honor of Yuri Gurevich's 75th
birthday. The final publication is available at Springer via
http://dx.doi.org/10.1007/978-3-319-23534-9_1
Retrograde semaphorin-plexin signalling drives homeostatic synaptic plasticity.
Homeostatic signalling systems ensure stable but flexible neural activity and animal behaviour. Presynaptic homeostatic plasticity is a conserved form of neuronal homeostatic signalling that is observed in organisms ranging from Drosophila to human. Defining the underlying molecular mechanisms of neuronal homeostatic signalling will be essential in order to establish clear connections to the causes and progression of neurological disease. During neural development, semaphorin-plexin signalling instructs axon guidance and neuronal morphogenesis. However, semaphorins and plexins are also expressed in the adult brain. Here we show that semaphorin 2b (Sema2b) is a target-derived signal that acts upon presynaptic plexin B (PlexB) receptors to mediate the retrograde, homeostatic control of presynaptic neurotransmitter release at the neuromuscular junction in Drosophila. Further, we show that Sema2b-PlexB signalling regulates presynaptic homeostatic plasticity through the cytoplasmic protein Mical and the oxoreductase-dependent control of presynaptic actin. We propose that semaphorin-plexin signalling is an essential platform for the stabilization of synaptic transmission throughout the developing and mature nervous system. These findings may be relevant to the aetiology and treatment of diverse neurological and psychiatric diseases that are characterized by altered or inappropriate neural function and behaviour
Parametrically Excited Surface Waves: Two-Frequency Forcing, Normal Form Symmetries, and Pattern Selection
Motivated by experimental observations of exotic standing wave patterns in
the two-frequency Faraday experiment, we investigate the role of normal form
symmetries in the pattern selection problem. With forcing frequency components
in ratio m/n, where m and n are co-prime integers, there is the possibility
that both harmonic and subharmonic waves may lose stability simultaneously,
each with a different wavenumber. We focus on this situation and compare the
case where the harmonic waves have a longer wavelength than the subharmonic
waves with the case where the harmonic waves have a shorter wavelength. We show
that in the former case a normal form transformation can be used to remove all
quadratic terms from the amplitude equations governing the relevant resonant
triad interactions. Thus the role of resonant triads in the pattern selection
problem is greatly diminished in this situation. We verify our general results
within the example of one-dimensional surface wave solutions of the
Zhang-Vinals model of the two-frequency Faraday problem. In one-dimension, a
1:2 spatial resonance takes the place of a resonant triad in our investigation.
We find that when the bifurcating modes are in this spatial resonance, it
dramatically effects the bifurcation to subharmonic waves in the case of
forcing frequencies are in ratio 1/2; this is consistent with the results of
Zhang and Vinals. In sharp contrast, we find that when the forcing frequencies
are in ratio 2/3, the bifurcation to (sub)harmonic waves is insensitive to the
presence of another spatially-resonant bifurcating mode.Comment: 22 pages, 6 figures, late
Social Interactions vs Revisions, What is important for Promotion in Wikipedia?
In epistemic community, people are said to be selected on their knowledge
contribution to the project (articles, codes, etc.) However, the socialization
process is an important factor for inclusion, sustainability as a contributor,
and promotion. Finally, what does matter to be promoted? being a good
contributor? being a good animator? knowing the boss? We explore this question
looking at the process of election for administrator in the English Wikipedia
community. We modeled the candidates according to their revisions and/or social
attributes. These attributes are used to construct a predictive model of
promotion success, based on the candidates's past behavior, computed thanks to
a random forest algorithm.
Our model combining knowledge contribution variables and social networking
variables successfully explain 78% of the results which is better than the
former models. It also helps to refine the criterion for election. If the
number of knowledge contributions is the most important element, social
interactions come close second to explain the election. But being connected
with the future peers (the admins) can make the difference between success and
failure, making this epistemic community a very social community too
Enhancing crowdsourcing success: the role of creative and deliberate problem-solving styles
A growing number of firms are using crowdsourcing platforms to actively solicit the skills of external entities to help them solve innovation-related problems. Despite its increasing popularity, crowdsourcing has produced mixed success, because few external experts provide helpful solutions. The current research examines this issue by exploring why some external solvers are more successful than others. Grounded in dual-processing theory, this study combines survey and archival data to assess the impact of creative versus deliberate problem-solving styles on solving success. The results indicate that both styles can be effective, but their relative success depends on the amount of time a solver invests in a solution and his or her degree of contextual familiarity with the problem. Specifically, creative (deliberate) styles are more effective under conditions of high (low) contextual familiarity and shorter (longer) time investments. When solvers employ both styles, overall problem-solving success declines. Data source: surve
- …
