2,240 research outputs found
Minimal Effective Theory for Phonotactic Memory: Capturing Local Correlations due to Errors in Speech
Spoken language evolves constrained by the economy of speech, which depends
on factors such as the structure of the human mouth. This gives rise to local
phonetic correlations in spoken words. Here we demonstrate that these local
correlations facilitate the learning of spoken words by reducing their
information content. We do this by constructing a locally-connected
tensor-network model, inspired by similar variational models used for many-body
physics, which exploits these local phonetic correlations to facilitate the
learning of spoken words. The model is therefore a minimal model of phonetic
memory, where "learning to pronounce" and "learning a word" are one and the
same. A consequence of which is the learned ability to produce new words which
are phonetically reasonable for the target language; as well as providing a
hierarchy of the most likely errors that could be produced during the action of
speech. We test our model against Latin and Turkish words. (The code is
available on GitHub.)Comment: 16 pages; 7 fig
Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
We present the systemic Console, a new all-in-one, general-purpose software
package for the analysis and combined multiparameter fitting of Doppler radial
velocity (RV) and transit timing observations. We give an overview of the
computational algorithms implemented in the Console, and describe the tools
offered for streamlining the characterization of planetary systems. We
illustrate the capabilities of the package by analyzing an updated radial
velocity data set for the HD128311 planetary system. HD128311 harbors a pair of
planets that appear to be participating in a 2:1 mean motion resonance. We show
that the dynamical configuration cannot be fully determined from the current
data. We find that if a planetary system like HD128311 is found to undergo
transits, then self-consistent Newtonian fits to combined radial velocity data
and a small number of timing measurements of transit midpoints can provide an
immediate and vastly improved characterization of the planet's dynamical state.Comment: 10 pages, 5 figures, accepted for publication on PASP. Additional
material at http://www.ucolick.org/~smeschia/systemic.ph
Overview of the blood transfusion policy in preterms on the Neonatal Intensive Care Unit
Preterm infants on the Neonatal Intensive Care Unit receive a greater number of red cell transfusions than any other hospitalised group. Over the past twenty years research has focused on setting standards to determine when it is necessary to transfuse packed cells in this cohort, whilst exploring the use of red cell growth factors and other substrates judiciously in order to reduce and/or avoid red cell transfusions and limit donor exposure. One hundred and eighty-one blood transfusions were administered to 106 preterms less than 35 weeks gestation on the NICU during 2009 in Malta. The median (range) volume of blood used from each bag supplied by the Blood Transfusion Department was 25.8mls (10-50mls), the rest of which was discarded. Risk factors for transfusion included Extremely Low Birth Weight (less than 1kg) and a gestation of less than 30 weeks. The blood transfusion guidelines presently in use on the local NICU were reviewed and compared with more restrictive guidelines on other units and suggestions made to reduce transfusions in line with these guidelines.
A reduction in transfusion aliquots provided for neonates to just 50mls from the customary 250mls in a dedicated single-donor programme will safeguard limited health resources and minimise donor exposure.peer-reviewe
The Lick-Carnegie Exoplanet Survey: A Saturn-Mass Planet in the Habitable Zone of the Nearby M4V Star HIP 57050
Precision radial velocities from Keck/HIRES reveal a Saturn-mass planet
orbiting the nearby M4V star HIP 57050. The planet has a minimum mass of 0.3
Jupiter-mass, an orbital period of 41.4 days, and an orbital eccentricity of
0.31. V-band photometry reveals a clear stellar rotation signature of the host
star with a period of 98 days, well separated from the period of the radial
velocity variations and reinforcing a Keplerian origin for the observed
velocity variations. The orbital period of this planet corresponds to an orbit
in the habitable zone of HIP 57050, with an expected planetary temperature of
approximately 230 K. The star has a metallicity of [Fe/H] = 0.32+/-0.06 dex, of
order twice solar and among the highest metallicity stars in the immediate
solar neighborhood. This newly discovered planet provides further support that
the well-known planet-metallicity correlation for F, G, and K stars also
extends down into the M-dwarf regime. The a priori geometric probability for
transits of this planet is only about 1%. However, the expected eclipse depth
is ~7%, considerably larger than that yet observed for any transiting planet.
Though long on the odds, such a transit is worth pursuing as it would allow for
high quality studies of the atmosphere via transmission spectroscopy with HST.
At the expected planetary effective temperature, the atmosphere may contain
water clouds.Comment: 20 pages, 5 figures, 3 tables, to appear in the May 20 issue of ApJ
A 4-Planet System Orbiting the K0V Star HD 141399
We present precision radial velocity (RV) data sets from Keck-HIRES and from
Lick Observatory's new Automated Planet Finder Telescope and Levy Spectrometer
on Mt. Hamilton that reveal a multiple-planet system orbiting the nearby,
slightly evolved, K-type star HD 141399. Our 91 observations over 10.5 years
suggest the presence of four planets with orbital periods of 94.35, 202.08,
1070.35, and 3717.35 days and minimum masses of 0.46, 1.36, 1.22, and 0.69
Jupiter masses respectively. The orbital eccentricities of the three inner
planets are small, and the phase curves are well sampled. The inner two planets
lie just outside the 2:1 resonance, suggesting that the system may have
experienced dissipative evolution during the protoplanetary disk phase. The
fourth companion is a Jupiter-like planet with a Jupiter-like orbital period.
Its orbital eccentricity is consistent with zero, but more data will be
required for an accurate eccentricity determination.Comment: 11 pages, 13 figures, To appear in the Astrophysical Journa
Mid-Infrared Plasmonic Platform based on Heavily Doped Epitaxial Ge-on-Si: Retrieving the Optical Constants of Thin Ge Epilayers
The n-type Ge-on-Si epitaxial material platform enables a novel paradigm for
plasmonics in the mid-infrared, prompting the future development of
lab-on-a-chip and subwavelength vibrational spectroscopic sensors. In order to
exploit this material, through proper electrodynamic design, it is mandatory to
retrieve the dielectric constants of the thin Ge epilayers with high precision
due to the difference from bulk Ge crystals. Here we discuss the procedure we
have employed to extract the real and imaginary part of the dielectric
constants from normal incidence reflectance measurements, by combining the
standard multilayer fitting procedure based on the Drude model with
Kramers-Kronig transformations of absolute reflectance data in the
zero-transmission range of the thin film.Comment: Infrared, Millimeter, and Terahertz waves (IRMMW-THz), 2014 39th
International Conference o
Systematic Study of Two-Pion Production in NN Collisions -- from Single-Baryon to Di-Baryon Excitations
The two-pion production in nucleon-nucleon collisions has been studied by
exclusive and kinematically complete experiments from threshold up to =
1.36 GeV at CELSIUS-WASA. At near-threshold energies the total and differential
distributions for the and channels are dominated by
Roper excitation and its decay into and channels. At beam
energies 1.1 GeV the excitation governs the two-pion
production process. In the channel evidence is found for the
excitation of a higher-lying I=3/2 resonance, favorably the . The
isovector fusion processes leading to the deuteron and to quasi-stable He,
respectively, %with the production of an isovector pion-pair exhibit no or only
a modest ABC-effect, {\it i.e.} low-mass enhancement in the -invariant
mass spectrum, and can be described by conventional -channel
excitation. On the other hand, the isoscalar fusion process to the deuteron
%with the production of an isoscalar pion-pair exhibits a dramatic ABC-effect
correlated with a narrow resonance-like energy dependence in the total cross
section with a width of only 50 MeV and situated at a mass 90 MeV below the
mass.Comment: Proceedings HADRON0
Group-IV midinfrared plasmonics
The use of heavily doped semiconductors to achieve plasma frequencies in the mid-IR has been recently proposed as a promising way to obtain high-quality and tunable plasmonic materials. We introduce a plasmonic platform based on epitaxial n-type Ge grown on standard Si wafers by means of low-energy plasma-enhanced chemical vapor deposition. Due to the large carrier concentration achieved with P dopants and to the compatibility with the existing CMOS technology, SiGe plasmonics hold promises for mid-IR applications in optoelectronics, IR detection, sensing, and light harvesting. As a representative example, we show simulations of mid-IR plasmonic waveguides based on the experimentally retrieved dielectric constants of the grown materials
Mid-infrared n-Ge on Si Plasmonic Based Microbolometer Sensors
The detection and amplification of molecular absorption lines from a chemical weapons simulant is demonstrated using plasmonic antennas fabricated from n-Ge epitaxially grown on Si. A free-standing Si0.25Ge0.75 microbolometer detector with n-Ge plasmonic antenna is demonstrated as an integrated mid-infrared plasmonic sensor
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