3,025 research outputs found
Fruit Processing, Seed Viability And Dormancy Mechanisms Of Persoonia Sericea A. Cunn. ex R. Br. and P. Virgata R.Br. (Proteaceae)
The morphology of the fruit and difficulties with fruit processing impose major limitations to germination of Persoonia sericea and P. virgata. The mesocarp must be removed without harming the embryo. Fermentation of fruit or manual removal of the mesocarp was effective but digestion in 32% hydrochloric acid (HCl) completely inhibited germination. The endocarp is extremely hard and therefore very difficult and time consuming to remove without damaging the seeds. The most efficient method was cracking the endocarp with pliers, followed by manual removal of seeds. Germination was completely inhibited unless at least half of the endocarp was removed. Microbial contamination of the fruit and seeds was controlled by disinfestation and germination of the seed under aseptic conditions. The results suggest that dormancy in these species is primarily due to physical restriction of the embryo by the hard endocarp
Towards production of novel catalyst powders from supported size-selected clusters by multilayer deposition and dicing
A multilayer deposition method has been developed with the potential to capture and process atomic clusters generated by a high flux cluster beam source. In this deposition mode a series of sandwich structures each consisting of three layers—a carbon support layer, cluster layer and polymer release layer—is sequentially deposited to form a stack of isolated cluster layers, as confirmed by through-focal aberration-corrected HAADF STEM analysis. The stack can then be diced into small pieces by a mechanical saw. The diced pieces are immersed in solvent to dissolve the polymer release layer and form small platelets of supported clusters
Soft-Collinear Messengers: A New Mode in Soft-Collinear Effective Theory
It is argued that soft-collinear effective theory for processes involving
both soft and collinear partons, such as exclusive B-meson decays, should
include a new mode in addition to soft and collinear fields. These
"soft-collinear messengers" can interact with both soft and collinear particles
without taking them far off-shell. They thus can communicate between the soft
and collinear sectors of the theory. The relevance of the new mode is
demonstrated with an explicit example, and the formalism incorporating the
corresponding quark and gluon fields into the effective Lagrangian is
developed.Comment: 22 pages, 5 figures. Extended Section 6, clarifying the relevance of
different types of soft-collinear interaction
Dust in the reionization era: ALMA observations of a =8.38 Galaxy
We report on the detailed analysis of a gravitationally-lensed Y-band
dropout, A2744_YD4, selected from deep Hubble Space Telescope imaging in the
Frontier Field cluster Abell 2744. Band 7 observations with the Atacama Large
Millimeter Array (ALMA) indicate the proximate detection of a significant 1mm
continuum flux suggesting the presence of dust for a star-forming galaxy with a
photometric redshift of . Deep X-SHOOTER spectra confirms the high
redshift identity of A2744_YD4 via the detection of Lyman emission at
a redshift =8.38. The association with the ALMA detection is confirmed by
the presence of [OIII] 88m emission at the same redshift. Although both
emission features are only significant at the 4 level, we argue their
joint detection and the positional coincidence with a high redshift dropout in
the HST images confirms the physical association. Analysis of the available
photometric data and the modest gravitational magnification ()
indicates A2744_YD4 has a stellar mass of 210 M, a
star formation rate of M/yr and a dust mass of
610 M. We discuss the implications of the
formation of such a dust mass only 200 Myr after the onset of cosmic
reionisation.Comment: Accepted for publication in ApJ
Meta-Learning Probabilistic Inference For Prediction
This paper introduces a new framework for data efficient and versatile
learning. Specifically: 1) We develop ML-PIP, a general framework for
Meta-Learning approximate Probabilistic Inference for Prediction. ML-PIP
extends existing probabilistic interpretations of meta-learning to cover a
broad class of methods. 2) We introduce VERSA, an instance of the framework
employing a flexible and versatile amortization network that takes few-shot
learning datasets as inputs, with arbitrary numbers of shots, and outputs a
distribution over task-specific parameters in a single forward pass. VERSA
substitutes optimization at test time with forward passes through inference
networks, amortizing the cost of inference and relieving the need for second
derivatives during training. 3) We evaluate VERSA on benchmark datasets where
the method sets new state-of-the-art results, handles arbitrary numbers of
shots, and for classification, arbitrary numbers of classes at train and test
time. The power of the approach is then demonstrated through a challenging
few-shot ShapeNet view reconstruction task
Staircase polygons: moments of diagonal lengths and column heights
We consider staircase polygons, counted by perimeter and sums of k-th powers
of their diagonal lengths, k being a positive integer. We derive limit
distributions for these parameters in the limit of large perimeter and compare
the results to Monte-Carlo simulations of self-avoiding polygons. We also
analyse staircase polygons, counted by width and sums of powers of their column
heights, and we apply our methods to related models of directed walks.Comment: 24 pages, 7 figures; to appear in proceedings of Counting Complexity:
An International Workshop On Statistical Mechanics And Combinatorics, 10-15
July 2005, Queensland, Australi
A proximal retarding field analyzer for scanning probe energy loss spectroscopy
NanotechnologyPAPER • THE FOLLOWING ARTICLE IS OPEN ACCESSA proximal retarding field analyzer for scanning probe energy loss spectroscopyKarl Bauer, Shane Murphy and Richard E PalmerPublished 8 February 2017 • © 2017 IOP Publishing LtdNanotechnology, Volume 28, Number 10Download Article PDFFiguresReferencesDownload PDF1206 Total downloads 11 citation on Dimensions.Article has an altmetric score of 1Turn on MathJaxShare this articleShare this content via emailShare on FacebookShare on TwitterShare on Google+Share on CiteULikeShare on MendeleyHide article informationAuthor [email protected] affiliationsNanoscale Physics, Chemistry and Engineering Research Laboratory, School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United KingdomORCID iDsKarl Bauer https://orcid.org/0000-0003-0664-2082DatesReceived 10 October 2016Accepted 13 January 2017Accepted Manuscript online 13 January 2017Published 8 February 2017 Check for updates using CrossmarkPeer review informationMethod: Single-blindRevisions: 1Screened for originality? YesCitationKarl Bauer et al 2017 Nanotechnology 28 105711Create citation alertDOIhttps://doi.org/10.1088/1361-6528/aa5938Buy this article in print Journal RSS feed Sign up for new issue notificationsAbstractA compact proximal retarding field analyzer for scanning probe energy loss spectroscopy measurements is described. Using the scanning tunneling microscope (STM) tip as a field emission (FE) electron source in conjunction with this analyzer, which is placed at a glancing angle to the surface plane, FE sample current and electron reflectivity imaging may be performed simultaneously. This is demonstrated in measurements of Ag nanostructures prepared on graphite by electron-beam lithography, where a material contrast of 13% is observed, with a lateral resolution of 25 nm, between the silver and graphite in electron reflectivity images. Topological contrast mechanisms such as edge enhancement and shadowing are also observed, giving rise to additional features in the electron reflectivity images. The same instrument configuration has been used to measure electron energy loss spectra on bare graphite, where the zero loss peak, π band plasmon loss peak and secondary electron peaks are observed. Using this simple and compact analyzer an STM, with sufficient open access to the tip-sample junction, may easily be augmented to provide simultaneous elemental and topographic mapping, supplementing STM image measurements with FE sample current and electron reflectivity images, as well as electron energy loss spectroscopy measurements, in the same instrument
A Synaptic Basis for Auditory-Vocal Integration in the Songbird
Songbirds learn to sing by memorizing a tutor song that they then vocally mimic using auditory feedback. This developmental sequence suggests that brain areas that encode auditory memories communicate with brain areas for learned vocal control. In the songbird, the secondary auditory telencephalic region caudal mesopallium (CM) contains neurons that encode aspects of auditory experience. We investigated whether CM is an important source of auditory input to two sensorimotor structures implicated in singing, the telencephalic song nucleus interface (NIf) and HVC. We used reversible inactivation methods to show that activity in CM is necessary for much of the auditory-evoked activity that can be detected in NIf and HVC of anesthetized adult male zebra finches. Furthermore, extracellular and intracellular recordings along with spike-triggered averaging methods indicate that auditory selectivity for the bird’s own song is enhanced between CM and NIf. We used lentiviral-mediated tracing methods to confirm that CM neurons directly innervate NIf. To our surprise, these tracing studies also revealed a direct projection from CM to HVC. We combined irreversible lesions of NIf with reversible inactivation of CM to establish that CM supplies a direct source of auditory drive to HVC. Finally, using chronic recording methods, we found that CM neurons are active in response to song playback and during singing, indicating their potential importance to song perception and processing of auditory feedback. These results establish the functional synaptic linkage between sites of auditory and vocal learning and may identify an important substrate for learned vocal communication
- …