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In the favoured core-accretion model of formation of planetary systems, solid planetesimals accumulate to build up planetary cores, which then accrete nebular gas if they are sufficiently massive. Around M-dwarf stars ( the most common stars in our Galaxy), this model favours the formation of Earth-mass (M+) to Neptune-mass planets with orbital radii of 1 to 10 astronomical units (AU), which is consistent with the small number of gas giant planets known to orbit M-dwarf host stars(1-4). More than 170 extrasolar planets have been discovered with a wide range of masses and orbital periods, but planets of Neptune's mass or less have not hitherto been detected at separations of more than 0.15 AU from normal stars. Here we report the discovery of a 5.5(-2.7)(+5.5)M(+) planetary companion at a separation of 2.6(- 0.6)(+1.5) AU from a 0.22(-0.11)(+0.21)M(.) M-dwarf star, where M-. refers to a solar mass. (We propose to name it OGLE- 2005-BLG-390Lb, indicating a planetary mass companion to the lens star of the microlensing event.) The mass is lower than that of GJ876d (ref. 5), although the error bars overlap. Our detection suggests that such cool, sub-Neptune-mass planets may be more common than gas giant planets, as predicted by the core accretion theory.
Myriapods (e. g., centipedes and millipedes) display a simple homonomous body plan relative to other arthropods. All members of the class are terrestrial, but they attained terrestriality independently of insects. Myriapoda is the only arthropod class not represented by a sequenced genome. We present an analysis of the genome of the centipede Strigamia maritima. It retains a compact genome that has undergone less gene loss and shuffling than previously sequenced arthropods, and many orthologues of genes conserved from the bilaterian ancestor that have been lost in insects. Our analysis locates many genes in conserved macro-synteny contexts, and many small-scale examples of gene clustering. We describe several examples where S. maritima shows different solutions from insects to similar problems. The insect olfactory receptor gene family is absent from S. maritima, and olfaction in air is likely effected by expansion of other receptor gene families. For some genes S. maritima has evolved paralogues to generate coding sequence diversity, where insects use alternate splicing. This is most striking for the Dscam gene, which in Drosophila generates more than 100,000 alternate splice forms, but in S. maritima is encoded by over 100 paralogues. We see an intriguing linkage between the absence of any known photosensory proteins in a blind organism and the additional absence of canonical circadian clock genes. The phylogenetic position of myriapods allows us to identify where in arthropod phylogeny several particular molecular mechanisms and traits emerged. For example, we conclude that juvenile hormone signalling evolved with the emergence of the exoskeleton in the arthropods and that RR-1 containing cuticle proteins evolved in the lineage leading to Mandibulata. We also identify when various gene expansions and losses occurred. The genome of S. maritima offers us a unique glimpse into the ancestral arthropod genome, while also displaying many adaptations to its specific life history.
F2 slope as a Perceptual Cue for the Front-Back Contrast in Standard Southern British English
(2017)
Acoustic studies of several languages indicate that second-formant (F2) slopes in high vowels have opposing directions (independent of consonantal context): front [i.]-like vowels are produced with a rising F2 slope, whereas back [u.]-like vowels are produced with a falling F2 slope. The present study first reports acoustic measurements that confirm this pattern for the English variety of Standard Southern British English (SSBE), where /u./ has shifted from the back to the front area of the vowel space and is now realized with higher midpoint F2 values than several decades ago. Subsequently, we test whether the direction of F2 slope also serves as a reliable cue to the /i.// u./ contrast in perception. The findings show that F2 slope direction is used as a cue (additional to midpoint formant values) to distinguish /i./ from /u./by both young and older Standard Southern British English listeners: an otherwise ambiguous token is identified as /i./if it has a rising F2 slope and as /u./if it has a falling F2 slope. Furthermore, our results indicate that listeners generalize their reliance on F2 slope to other contrasts, namely /epsilon/-/./and /ae/-/./, even though F2 slope is not employed to differentiate these vowels in production. This suggests that in Standard Southern British English, a rising F2 seems to be perceptually associated with an abstract feature such as [+ front], whereas a falling F2 with an abstract feature such as [-front].
We analyze the photometric data obtained by PLANET and OGLE on the caustic-crossing binary-lens microlensing event OGLE-2002-BLG-069. Thanks to the excellent photometric and spectroscopic coverage of the event, we are able to constrain the lens model up to the known ambiguity between close and wide binary lenses. The detection of annual parallax in combination with measurements of extended-source effects allows us to determine the mass, distance and velocity of the lens components for the competing models. While the model involving a close binary lens leads to a Bulge- Disc lens scenario with a lens mass of M = (0.51 ± 0.15) M-⊙ and distance of D-L = (2.9 ± 0.4) kpc, the wide binary lens solution requires a rather implausible binary black-hole lens ( M ≳ 126 M-⊙). Furthermore we compare current state-of-the-art numerical and empirical models for the surface brightness profile of the source, a G5III Bulge giant. We find that a linear limb-darkening model for the atmosphere of the source star is consistent with the data whereas a PHOENIX atmosphere model assuming LTE and with no free parameter does not match our observations
We discuss high-resolution, time-resolved spectra of the caustic exit of the binary microlensing event OGLE 2002-BLG-069 obtained with UVES on the VLT. The source star is a G5III giant in the Galactic Bulge. During such events, the source star is highly magnified, and a strong differential magnification around the caustic resolves its surface. Using an appropriate model stellar atmosphere generated by the PHOENIX v2.6 code we obtain a model light curve for the caustic exit and compare it with a dense set of photometric observations obtained by the PLANET microlensing follow up network. We further compare predicted variations in the Halpha equivalent width with those measured from our spectra. While the model and observations agree in the gross features, there are discrepancies suggesting shortcomings in the model, particularly for the Halpha line core, where we have detected amplified emission from the stellar chromosphere after the source star's trailing limb exited the caustic. This achievement became possible by the provision of the very efficient OGLE-III Early Warning System, a network of small telescopes capable of nearly-continuous round-the-clock photometric monitoring, on-line data reduction, daily near-real-time modelling in order to predict caustic crossing parameters, and a fast and efficient response of a 8 m class telescope to a "Target-of-Opportunity" observation request
Microlensing is the only known direct method to measure the masses of stars that lack visible companions. In terms of microlensing observables, the mass is given by M (c(2)/4G)(r) over tilde (E)theta(E) and so requires the measurement of both the angular Einstein radius theta(E) and the projected Einstein radius (r) over tilde (E). Simultaneous measurement of these two parameters is extremely rare. Here we analyze OGLE-2003-BLG-238, a spectacularly bright (I-min 10.3), high-magnification (A(max) 170) microlensing event. Pronounced finite-source effects permit a measurement of theta(E) = 650 muas. Although the timescale of the event is only t(E) 38 days, one can still obtain weak constraints on the microlens parallax: 4.4 AU < <(r)over tilde>(E) < 18 AU at the 1 σ level. Together these two parameter measurements yield a range for the lens mass of 0.36 M-&ODOT; < M < 1.48 M-&ODOT;. As was the case for MACHO- LMC-5, the only other single star (apart from the Sun) whose mass has been determined from its gravitational effects, this estimate is rather crude. It does, however, demonstrate the viability of the technique. We also discuss future prospects for single-lens mass measurements
Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1-7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of ''exoplanet discovery space'' - toward smaller masses and larger orbital radii - that are inaccessible to the Doppler velocity technique.
Dark matter constraints from a joint analysis of dwarf Spheroidal galaxy observations with VERITAS
(2017)
We present constraints on the annihilation cross section of weakly interacting massive particles dark matter based on the joint statistical analysis of four dwarf galaxies with VERITAS. These results are derived from an optimized photon weighting statistical technique that improves on standard imaging atmospheric Cherenkov telescope (IACT) analyses by utilizing the spectral and spatial properties of individual photon events. We report on the results of similar to 230 hours of observations of five dwarf galaxies and the joint statistical analysis of four of the dwarf galaxies. We find no evidence of gamma-ray emission from any individual dwarf nor in the joint analysis. The derived upper limit on the dark matter annihilation cross section from the joint analysis is 1.35 x 10(-23) cm(3) s(-1) at 1 TeV for the bottom quark (b (b) over bar) final state, 2.85 x 10(-24) cm(3) s(-1) at 1 TeV for the tau lepton (tau+tau(-)) final state and 1.32 x 10-25 cm(3) s(-1) at 1 TeV for the gauge boson (gamma gamma) final state.
This study compares the duration and first two formants (F1 and F2) of 11 nominal monophthongs and five nominal diphthongs in Standard Southern British English (SSBE) and a Northern English dialect. F1 and F2 trajectories were fitted with parametric curves using the discrete cosine transform (DCT) and the zeroth DCT coefficient represented formant trajectory means and the first DCT coefficient represented the magnitude and direction of formant trajectory change to characterize vowel inherent spectral change (VISC). Cross-dialectal comparisons involving these measures revealed significant differences for the phonologically back monophthongs /D, , , u:/ and also /3z:/ and the diphthongs /eI, e, aI, I/. Most cross-dialectal differences are in zeroth DCT coefficients, suggesting formant trajectory means tend to characterize such differences, while first DCT coefficient differences were more numerous for diphthongs. With respect to VISC, the most striking differences are that /u:/is considerably more diphthongized in the Northern dialect and that the F2 trajectory of /e/proceeds in opposite directions in the two dialects. Cross-dialectal differences were found to be largely unaffected by the consonantal context in which the vowels were produced. The implications of the results are discussed in relation to VISC, consonantal context effects and speech perception. (c) 2014 Acoustical Society of America.
Uncovering the acoustic vowel space of a previously undescribed language: The vowels of Nambo
(2016)
This study presents the first acoustic description of the vowel space of a Papuan language—Nambo, spoken in southern Papua New Guinea—based on duration and first and second formant measurements from 19 adult male and female speakers across three age groups (young, middle-aged, senior). Phonemically, Nambo has six full vowels /i, e, æ, ɑ, o, u/ and a reduced vowel tentatively labeled /ə/. Unlike the full vowels, the quality of /ə/ showed great variation: seniors' and young females' realizations tended to be more open and retracted than those by young males, while middle-aged speakers' productions fell between these two variants.
Dynamic acoustic properties of monophthongs and diphthongs in Western Sydney Australian English
(2016)
This study provides a thorough acoustic analysis of the 18 Australian English monophthongs and diphthongs produced in a variety of phonetic contexts by young adult speakers from Western Sydney. The 18 vowels are well separated by duration and dynamic formant trajectory information. Vowel durations and formant trajectories were affected by the consonantal context in which the vowels were produced, particularly those produced in the /hVd/ context. Finally, the results indicate that capturing aspects of vowel inherent spectral change may be useful in future cross-dialectal and cross-linguistic studies. (C) 2016 Acoustical Society of America.
Aims and objectives: This study investigates the effects of individual bilingualism and long-term language contact on monophthongal vowel productions in English and Welsh. Design: To this end, we recorded the Welsh and English vowel productions of two sets of Welsh-English bilinguals differing in home language use, as well as the English vowel productions of English monolinguals. Data and analysis: The data were analysed acoustically, with a focus on spectral and temporal properties. Comparisons were then made within each language and cross-linguistically. Findings: The results of a cross-linguistic acoustic comparison revealed a high degree of convergence in the monophthong systems of Welsh and English, but also some language-specific categories. Interestingly, at the individual level we found no effect of linguistic experience on vowel production: the two sets of bilinguals and the English monolinguals did not differ in their realisation of English vowels, and the two sets of bilinguals did not differ in their realisation of Welsh vowels. Implications: The findings demonstrate pervasive phonetic convergence in a language contact situation with a historical substrate. They also indicate that a homogeneous peer group with shared values can override the effects of individual linguistic experience.
On 2019 April 25.346 and 26.640 UT the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo gravitational-wave (GW) observatory announced the detection of the first candidate events in Observing Run 3 that contained at least one neutron star (NS). S190425z is a likely binary neutron star (BNS) merger at d(L) = 156 +/- 41 Mpc, while S190426c is possibly the first NS-black hole (BH) merger ever detected, at d(L) = 377 +/- 100 Mpc, although with marginal statistical significance. Here we report our optical follow-up observations for both events using the MMT 6.5 m telescope, as well as our spectroscopic follow-up of candidate counterparts (which turned out to be unrelated) with the 4.1 m SOAR telescope. We compare to publicly reported searches, explore the overall areal coverage and depth, and evaluate those in relation to the optical/near-infrared (NIR) kilonova emission from the BNS merger GW170817, to theoretical kilonova models, and to short gamma-ray burst (SGRB) afterglows. We find that for a GW170817-like kilonova, the partial volume covered spans up to about 40% for S190425z and 60% for S190426c. For an on-axis jet typical of SGRBs, the search effective volume is larger, but such a configuration is expected in at most a few percent of mergers. We further find that wide-field gamma-ray and X-ray limits rule out luminous on-axis SGRBs, for a large fraction of the localization regions, although these searches are not sufficiently deep in the context of the gamma-ray emission from GW170817 or off-axis SGRB afterglows. The results indicate that some optical follow-up searches are sufficiently deep for counterpart identification to about 300 Mpc, but that localizations better than 1000 deg(2) are likely essential.
In a cue-distractor task, speakers' response times (RTs) were found to speed up when they perceived a distractor syllable whose vowel was identical to the vowel in the syllable they were preparing to utter. At a more fine-grained level, subphonemic congruency between response and distractor-defined by higher number of shared phonological features or higher acoustic proximity-was also found to be predictive of RT modulations. Furthermore, the findings indicate that perception of vowel stimuli embedded in syllables gives rise to robust and more consistent perceptuomotor compatibility effects (compared to isolated vowels) across different response-distractor vowel pairs.
Perceptuomotor compatibility between phonemically identical spoken and perceived syllables has been found to speed up response times (RTs) in speech production tasks. However, research on compatibility effects between perceived and produced stimuli at the subphonemic level is limited. Using a cue-distractor task, we investigated the effects of phonemic and subphonemic congruency in pairs of vowels. On each trial, a visual cue prompted individuals to produce a response vowel, and after the visual cue appeared a distractor vowel was auditorily presented while speakers were planning to produce the response vowel. The results revealed effects on RTs due to phonemic congruency (same vs. different vowels) between the response and distractor vowels, which resemble effects previously seen for consonants. Beyond phonemic congruency, we assessed how RTs are modulated as a function of the degree of subphonemic similarity between the response and distractor vowels. Higher similarity between the response and distractor in terms of phonological distance-defined by number of mismatching phonological features-resulted in faster RTs. However, the exact patterns of RTs varied across response-distractor vowel pairs. We discuss how different assumptions about phonological feature representations may account for the different patterns observed in RTs across response-distractor pairs. Our findings on the effects of perceived stimuli on produced speech at a more detailed level of representation than phonemic identity necessitate a more direct and specific formulation of the perception-production link. Additionally, these results extend previously reported perceptuomotor interactions mainly involving consonants to vowels.
During an unusually massive filament eruption on 7 June 2011, SDO/AIA imaged for the first time significant EUV emission around a magnetic reconnection region in the solar corona. The reconnection occurred between magnetic fields of the laterally expanding CME and a neighbouring active region. A pre-existing quasi-separatrix layer was activated in the process. This scenario is supported by data-constrained numerical simulations of the eruption. Observations show that dense cool filament plasma was re-directed and heated in situ, producing coronal-temperature emission around the reconnection region. These results provide the first direct observational evidence, supported by MHD simulations and magnetic modelling, that a large-scale re-configuration of the coronal magnetic field takes place during solar eruptions via the process of magnetic reconnection.
Spectral change and duration as cues in Australian English listeners' front vowel categorization
(2018)
Australian English /iː/, /ɪ/, and /ɪə/ exhibit almost identical average first (F1) and second (F2) formant frequencies and differ in duration and vowel inherent spectral change (VISC). The cues of duration, F1 × F2 trajectory direction (TD) and trajectory length (TL) were assessed in listeners' categorization of /iː/ and /ɪə/ compared to /ɪ/. Duration was important for distinguishing both /iː/ and /ɪə/ from /ɪ/. TD and TL were important for categorizing /iː/ versus /ɪ/, whereas only TL was important for /ɪə/ versus /ɪ/. Finally, listeners' use of duration and VISC was not mutually affected for either vowel compared to /ɪ/.
Speech scientists have long noted that the qualities of naturally-produced vowels do not remain constant over their durations regardless of being nominally "monophthongs" or "diphthongs". Recent acoustic corpora show that there are consistent patterns of first (F1) and second (F2) formant frequency change across different vowel categories. The three Australian English (AusE) close front vowels /i:, 1, i/ provide a striking example: while their midpoint or mean F1 and F2 frequencies are virtually identical, their spectral change patterns distinctly differ. The results indicate that, despite the distinct patterns of spectral change of AusE /i:, i, la/ in production, its perceptual relevance is not uniform, but rather vowel-category dependent.