1,721,325 research outputs found
Chiral symmetry breaking and confinement effects on dilepton and photon production aroundTc
No full textProduction rates of dileptons and photons from the quark-gluon (QGP) phase
are calculated taking into account effects of confinement and spontaneous
chiral symmetry breaking (\chi SB) not far from the transition temperature
. We find that the production rates of dileptons with large momenta and of
photons originating from the QGP around are suppressed by the \chi SB
effect. We also discuss to what extent information about details of the chiral
transition, such as its characteristic temperature range and the steepness of
the crossover, are reflected in these quantities
Spectral properties of the Goldstino in supersymmetric Bose-Fermi mixtures
No full textWe evaluate the spectral properties of the Goldstino in a Bose-Fermi mixture of cold atoms and molecules whose dynamics is governed by a supersymmetric hamiltonian. Model independent results are obtained from sum rules obeyed by the spectral function. We carry out specific calculations, at zero and finite temperature, using the Random Phase Approximation, and obtain in particular analytic expressions for the dispersion relation at small momentum. These explicit calculations allow us to pin down more precisely the features of the Goldstino that can be attributed to the supersymmetry alone, together with its spontaneous breaking. The anomalous large effect of the Fermi sea at moderate and large momenta is emphasized
Secondary‐tail formation during stolonization in the Japanese green syllid, Megasyllis nipponica
No full textAbstract
Benthic annelids belonging to the family Syllidae show a distinctive sexual reproduction mode called “stolonization,” in which posterior segments are transformed into a reproductive individual‐like unit called a “stolon.”
Megasyllis nipponica
forms a stolon head and a secondary tail in the middle of the trunk before a stolon detaches, while, in the case of posterior amputation, posterior regeneration initiates at the wound after amputation. To understand the difference between posterior regeneration and secondary‐tail formation during stolonization, detailed comparisons between the developmental processes of these two tail‐formation types were performed in this study. Morphological and inner structural observations (i.e., cell proliferation and muscular/nervous development) showed that some processes of posterior regeneration, such as blastema formation and muscular/nervous regeneration at the amputation site, are missing during secondary‐tail formation. In contrast, the secondary tail showed some unique features, such as the formation of ventrolateral half‐tail buds that later fused in the middle and muscle/nerve branches formed before the detachment of the stolon. These novel features in the process of stolonization are suggested to be adaptive since the animals need to recover a posterior end quickly to stolonize again.Research Highlights
Megasyllis nipponica
forms a pair of half‐tail buds that fuse into a secondary tail before the detachment of a stolon.
Secondary‐tail formation shows morphological and inner structural differences from posterior regeneration after amputation.Abstract
Benthic annelids belonging to the family Syllidae show a distinctive sexual reproduction mode called “stolonization,” in which posterior segments are transformed into a reproductive individual‐like unit called a “stolon.”
Megasyllis nipponica
forms a stolon head and a secondary tail in the middle of the trunk before a stolon detaches, while, in the case of posterior amputation, posterior regeneration initiates at the wound after amputation. To understand the difference between posterior regeneration and secondary‐tail formation during stolonization, detailed comparisons between the developmental processes of these two tail‐formation types were performed in this study. Morphological and inner structural observations (i.e., cell proliferation and muscular/nervous development) showed that some processes of posterior regeneration, such as blastema formation and muscular/nervous regeneration at the amputation site, are missing during secondary‐tail formation. In contrast, the secondary tail showed some unique features, such as the formation of ventrolateral half‐tail buds that later fused in the middle and muscle/nerve branches formed before the detachment of the stolon. These novel features in the process of stolonization are suggested to be adaptive since the animals need to recover a posterior end quickly to stolonize again.Research Highlights
Megasyllis nipponica
forms a pair of half‐tail buds that fuse into a secondary tail before the detachment of a stolon.
Secondary‐tail formation shows morphological and inner structural differences from posterior regeneration after amputation.Japan Society for the Promotion of Science https://doi.org/10.13039/50110000169
Dilepton and photon production in the presence of a nontrivial Polyakov loop
Full text linkWe calculate the production of dileptons and photons in the presence of a nontrivial Polyakov loop in QCD. This is applicable to the semi-Quark Gluon Plasma (QGP), at temperatures above but near the critical temperature for deconfinement. The Polyakov loop is small in the semi-QGP, and near unity in the perturbative QGP. Working to leading order in the coupling constant of QCD, we find that there is a mild enhancement, ~ 20%, for dilepton production in the semi-QGP over that in the perturbative QGP. In contrast, we find that photon production is strongly suppressed in the semi-QGP, by about an order of
magnitude, relative to the perturbative QGP. In the perturbative QGP photon production contains contributions from 2->2 scattering and collinear emission with the Landau- Pomeranchuk-Migdal (LPM) effect. In the semi-QGP we show that the two contributions are modified differently. The rate for 2->2 scattering is suppressed by a factor which depends upon the Polyakov loop. In contrast, in an SU(N) gauge theory the collinear rate is suppressed by 1/N, so that the LPM effect vanishes at infinite N. To leading order in the semi-QGP at large N, we compute the rate from 2->2 scattering to the leading logarithmic order and the collinear rate to leading order
Emissions analyses of humidified cracked ammonia swirling flames
Full text linkUsing renewably produced ammonia as a zero-carbon fuel is gaining momentum due to its ease of transportation and storage as a hydrogen vector. This is particularly true for partially cracking ammonia immediately prior to use, injecting a blend of NH3, H2 and N2. Challenges with this fuel combination relate to the emissions of NOx and unburned NH3, as well as understanding flame stability for practical applications. In this study, a 20 %(vol.) cracked ammonia blend was investigated using a fully premixed swirl burner, operating at a thermal power of 10 kW with steam injection of 30 %(vol.) of the fuel and preheating inlet temperatures of up to 390 K, for a range of equivalence ratios from lean to rich. Emissions of NO, NO2, N2O, NH3, H2, O2 and H2O were recorded, along with OH*, NH* and NH2* chemiluminescence. Additionally, a numerical investigation was conducted using CHEMKIN-PRO to elucidate the main reactions responsible for reducing emissions by providing a rate of production analysis. The 20 %(vol.) cracked ammonia blend was found to reduce NO, NO2 and N2O significantly, with an increase in NH3 emissions at rich conditions and instabilities at both lean and rich extremes, compared to the widely investigated 70/30(vol %) ammonia/hydrogen blend. Humidification reduced NO and NO2 emissions due
to a reduction in HNO production via OH and NH but caused an increase in N2O by reducing the flame temperature and unburned NH3 emissions at rich, low power conditions due to combustion instabilities. Unburned H2 emissions however were reduced, likely relating to a reduction in exhaust temperature thermally cracking less unburned NH3 into H2 and N2
Two new species of Syllidae (Annelida) from Misaki Bay and Sugashima Island, Japan
No full textThe shorelines of Japan host diverse ecosystems, particularly in the shallow coastal waters, which are rich in syllid species. This study describes two new Syllidae species: Virchowia christophi sp. nov., discovered at Misaki and Sugashima Island, and Paraopisthosyllis rufa sp. nov., found at Misaki. Additionally, we provide a redescription of Syllis okadai Fauvel, 1913, based on specimens collected from Misaki. Virchowia christophi sp. nov. shows a unique combination of characters, such as branched nuchal epaulettes together with a complex colouration pattern featuring white, beige, and brown transverse lines, along with white refringent dots, and chaetae with long distal teeth. The second new species, Paraopisthosyllis rufa sp. nov., is distinguished from similar species by its vivid red colouration and segments secondarily triannulated. Paraopisthosyllis rufa sp. nov. is able to generate a secondary ventral tail while the developing stolon (reproductive unit) is still attached to the parental stock. This trait has previously been observed in species of Megasyllis San Martín et al. 2008 and Alcyonosyllis Glasby & Watson, 2001, two genera that are phylogenetically closely related to Paraopisthosyllis Hartmann-Schröder, 1991. This is the first report of the genus Paraopisthosyllis from Japan. Dense ciliation around eyes is identified as a new characteristic of Syllis okadai and its stolons are described in detail. The phylogenetic position of all three species is investigated using maximum likelihood, combining three genes (18S, 16S, COI). Paraopisthosyllis rufa sp. nov. forms a monophyletic clade with other Paraopisthosyllis species. Syllis okadai from Misaki is sister to the already investigated Syllis okadai from Manazuru, Japan. Virchowia christophi sp. nov. has an ambiguous phylogenetic position within Autolytinae since current molecular data suggests that Virchowia Langerhans, 1879 might be paraphyletic.
Effects of Quadripulse Stimulation on Human Motor Cortex Excitability: A Replication Study
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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