3,945 research outputs found
Numerical Studies of Three-dimensional Breakdown in Trailing Vortex Wakes
Finite element, three dimensional relaxation methods are used to calculate the development of vortex wakes behind aircraft for a considerable downstream distance. The inclusion of a self-induction term in the solution, dependent upon local curvature and vortex core radius, permits calculation of finite lifetimes for systems for which infinite life would be predicted two dimensionally. The associated computer program is described together with single-pair, twin-pair, and multiple-pair studies carried out using it. It is found, in single-pair studies, that there is a lower limit to the wavelengths at which the Crow-type of instability can occur. Below this limit, self-induction effects cause the plane of the disturbance waves to rotate counter to the vortex direction. Self induction in two dimensionally generated twin spiral waves causes an increase in axial length which becomes more marked with decreasing initial wavelength. The time taken for vortex convergence toward the center plane is correspondingly increased. The limited parametric twin-pair study performed suggests that time-to-converge increases with increasing flap span. Limited studies of Boeing 747 configurations show correct qualitative response to removal of the outer flap and to gear deployment, as compared with wind tunnel and flight test experience
Machine learning with the hierarchyâofâhypotheses (HoH) approach discovers novel pattern in studies on biological invasions
Research synthesis on simple yet general hypotheses and ideas is challenging in scientific disciplines studying highly contextâdependent systems such as medical, social, and biological sciences. This study shows that machine learning, equationâfree statistical modeling of artificial intelligence, is a promising synthesis tool for discovering novel patterns and the source of controversy in a general hypothesis. We apply a decision tree algorithm, assuming that evidence from various contexts can be adequately integrated in a hierarchically nested structure. As a case study, we analyzed 163 articles that studied a prominent hypothesis in invasion biology, the enemy release hypothesis. We explored if any of the nine attributes that classify each study can differentiate conclusions as classification problem. Results corroborated that machine learning can be useful for research synthesis, as the algorithm could detect patterns that had been already focused in previous narrative reviews. Compared with the previous synthesis study that assessed the same evidence collection based on experts' judgement, the algorithm has newly proposed that the studies focusing on Asian regions mostly supported the hypothesis, suggesting that more detailed investigations in these regions can enhance our understanding of the hypothesis. We suggest that machine learning algorithms can be a promising synthesis tool especially where studies (a) reformulate a general hypothesis from different perspectives, (b) use different methods or variables, or (c) report insufficient information for conducting metaâanalyses
Locality and Translations in Braided Ribbon Networks
An overview of microlocality in braided ribbon networks is presented.
Following this, a series of definitions are presented to explore the concept of
microlocality and the topology of ribbon networks. Isolated substructure of
ribbon networks are introduced, and a theorem is proven that allows them to be
relocated. This is followed by a demonstration of microlocal translations.
Additionally, an investigation into macrolocality and the implications of
invariants in braided ribbon networks are presented.Comment: 12 pages, 12 figure
Young people who display harmful sexual behaviors and their families : a qualitative systematic review of their experiences of professional interventions.
It is estimated that 30â50% of all childhood sexual abuse involves other young people as perpetrators. The treatment of harmful sexual behavior (HSB) in young people has evolved from interventions developed for use with adult perpetrators of sexual offenses. Increasingly, these approaches were not seen as appropriate for use with young people. The purpose of this qualitative systematic review was to establish what intervention components are viewed as acceptable or useful by young people and their families in order to inform the development of interventions for young people with HSB. We conducted searches across 14 electronic databases as well as contacting experts to identify relevant studies. Thirteen qualitative studies were included in the analysis, reporting findings from intervention studies from the United Kingdom, United States, New Zealand, Australia, and Ireland. Thematic analysis was used to combine findings from the studies of young people and parent/carers views. Five key themes were identified as critical components of successful interventions for young people with HSB. These included the key role of the relationship between the young person and practitioner, the significance of the role of parents and carers, the importance of considering the wider context in which the abuse has occurred, the role of disclosure in interventions, and the need to equip young people with skills as well as knowledge. The evidence was limited by the small number of studies that were mainly from the perspectives of adolescent males
Insights into a dinoflagellate genome through expressed sequence tag analysis
BACKGROUND: Dinoflagellates are important marine primary producers and grazers and cause toxic "red tides". These taxa are characterized by many unique features such as immense genomes, the absence of nucleosomes, and photosynthetic organelles (plastids) that have been gained and lost multiple times. We generated EST sequences from non-normalized and normalized cDNA libraries from a culture of the toxic species Alexandrium tamarense to elucidate dinoflagellate evolution. Previous analyses of these data have clarified plastid origin and here we study the gene content, annotate the ESTs, and analyze the genes that are putatively involved in DNA packaging. RESULTS: Approximately 20% of the 6,723 unique (11,171 total 3'-reads) ESTs data could be annotated using Blast searches against GenBank. Several putative dinoflagellate-specific mRNAs were identified, including one novel plastid protein. Dinoflagellate genes, similar to other eukaryotes, have a high GC-content that is reflected in the amino acid codon usage. Highly represented transcripts include histone-like (HLP) and luciferin binding proteins and several genes occur in families that encode nearly identical proteins. We also identified rare transcripts encoding a predicted protein highly similar to histone H2A.X. We speculate this histone may be retained for its role in DNA double-strand break repair. CONCLUSION: This is the most extensive collection to date of ESTs from a toxic dinoflagellate. These data will be instrumental to future research to understand the unique and complex cell biology of these organisms and for potentially identifying the genes involved in toxin production
Sub-Nyquist Field Trial Using Time Frequency Packed DP-QPSK Super-Channel Within Fixed ITU-T Grid
Sub-Nyquist time frequency packing technique was demonstrated for the first
time in a super channel field trial transmission over long-haul distances. The
technique allows a limited spectral occupancy even with low order modulation
formats. The transmission was successfully performed on a deployed Australian
link between Sydney and Melbourne which included 995 km of uncompensated SMF
with coexistent traffic. 40 and 100 Gb/s co-propagating channels were
transmitted together with the super-channel in a 50 GHz ITU-T grid without
additional penalty. The super-channel consisted of eight sub-channels with
low-level modulation format, i.e. DP-QPSK, guaranteeing better OSNR robustness
and reduced complexity with respect to higher order formats. At the receiver
side, coherent detection was used together with iterative maximum-a-posteriori
(MAP) detection and decoding. A 975 Gb/s DP-QPSK super-channel was successfully
transmitted between Sydney and Melbourne within four 50GHz WSS channels (200
GHz). A maximum potential SE of 5.58 bit/s/Hz was achieved with an OSNR=15.8
dB, comparable to the OSNR of the installed 100 Gb/s channels. The system
reliability was proven through long term measurements. In addition, by closing
the link in a loop back configuration, a potential SE*d product of 9254
bit/s/Hz*km was achieved
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Identification of novel transcripts and peptides in developing murine lens.
We previously investigated the transcriptome and proteome profiles of the murine ocular lens at six developmental time points including two embryonic (E15 and E18) and four postnatal time points (P0, P3, P6, and P9). Here, we extend our analyses to identify novel transcripts and peptides in developing mouse lens. We identified a total of 9,707 novel transcripts and 325 novel fusion genes in developing mouse lens. Additionally, we identified 13,281 novel alternative splicing (AS) events in mouse lens including 6,990 exon skipping (ES), 2,447 alternative 3' splice site (A3SS), 1,900 alternative 5' splice site (A5SS), 1,771 mutually exclusive exons (MXE), and 173 intron retention (IR). Finally, we integrated our OMIC (Transcriptome and Proteome) datasets identifying 20 novel peptides in mouse lens. All 20 peptides were validated through matching MS/MS spectra of synthetic peptides. To the best of our knowledge, this is the first report integrating OMIC datasets to identify novel peptides in developing murine lens
Infinite Degeneracy of States in Quantum Gravity
The setting of Braided Ribbon Networks is used to present a general result in
spin-networks embedded in manifolds: the existence of an infinite number of
species of conserved quantities. Restricted to three-valent networks the number
of such conserved quantities in a given network is shown to be invariant
barring a single case. The implication of these conserved quantities is
discussed in the context of Loop Quantum Gravity.Comment: 10 pages, 14 figures, v2: some clarifications, no substantial change
Subnational sustainable development: The role of vertical intergovernmental transfers in reaching multidimensional goals
Achieving sustainable development hinges on two critical factors: the subnational implementation of public policies and the efficient allocation of resources across regions through vertical intergovernmental transfers. We introduce a framework that links these two mechanisms for analyzing the impact of reallocating federal transfers in the presence of regional heterogeneity from development indicators, budget sizes, expenditure returns, and long-term structural factors. Our study focuses on the case of Mexico and its 32 states. Using an agent-based computational model, we estimate the development gaps that will remain by the year 2030, and characterize their sensitivity to changes in the statesâ budget sizes. Then, we estimate the optimal distribution of federal transfers to minimize these gaps. Crucially, these distributions depend on the specific development objectives set by the national government, and by various interdependencies between the heterogeneous qualities of the states. This work sheds new light on the complex problem of budgeting for the Sustainable Development Goals at the subnational level, and it is especially relevant for the study of fiscal decentralization from the expenditure point of view
Quark-quark correlations and baryon electroweak observables
The simple independent quark models have difficulties explaining
simultaneously the totality of the known hyperon magnetic moments and hyperon
semi-leptonic decay rates. We show that both the Goldstone boson loop
contributions and the two-quark effective exchange currents are essential in
explaining these observables.Comment: 7 pages, 1 figur
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