716 research outputs found
Disruption to control network function correlates with altered dynamic connectivity in the wider autism spectrum.
Autism is a common developmental condition with a wide, variable range of co-occurring neuropsychiatric symptoms. Contrasting with most extant studies, we explored whole-brain functional organization at multiple levels simultaneously in a large subject group reflecting autism's clinical diversity, and present the first network-based analysis of transient brain states, or dynamic connectivity, in autism. Disruption to inter-network and inter-system connectivity, rather than within individual networks, predominated. We identified coupling disruption in the anterior-posterior default mode axis, and among specific control networks specialized for task start cues and the maintenance of domain-independent task positive status, specifically between the right fronto-parietal and cingulo-opercular networks and default mode network subsystems. These appear to propagate downstream in autism, with significantly dampened subject oscillations between brain states, and dynamic connectivity configuration differences. Our account proposes specific motifs that may provide candidates for neuroimaging biomarkers within heterogeneous clinical populations in this diverse condition
Belousov-Zhabotinsky reaction in liquid marbles
In Belousov–Zhabotinsky (BZ) type reactions, chemical oxidation waves can be exploited to produce reaction-diffusion processors. This paper reports on a new method of encapsulating BZ solution in a powder coating of either polyethylene (PE) or polytetrafluoroethylene (PTFE), to produce BZ liquid marbles (LMs). BZ LMs have solid-liquid interfaces compared to previously reported encapsulation systems, BZ emulsions and BZ vesicles. Oscillation studies on individual LMs established PE-coated LMs were easier to prepare and more robust than PTFE-coated LMs. Therefore, this coating was used to study BZ LMs positioned in ordered and disordered arrays. Sporadic transfer of excitation waves was observed between LMs in close proximity to each other. These results lay the foundations for future studies on information transmission and processing arrays of BZ LMs. Future work aims to elucidate the effect of other physical stimuli on the dynamics of chemical excitation waves withinthese systems
On polymorphic logical gates in sub-excitable chemical medium
In a sub-excitable light-sensitive Belousov-Zhabotinsky chemical medium an
asymmetric disturbance causes the formation of localized traveling
wave-fragments. Under the right conditions these wave-fragment can conserve
their shape and velocity vectors for extended time periods. The size and life
span of a fragment depend on the illumination level of the medium. When two or
more wave-fragments collide they annihilate or merge into a new wave-fragment.
In computer simulations based on the Oregonator model we demonstrate that the
outcomes of inter-fragment collisions can be controlled by varying the
illumination level applied to the medium. We interpret these wave-fragments as
values of Boolean variables and design collision-based polymorphic logical
gates. The gate implements operation XNOR for low illumination, and it acts as
NOR gate for high illumination. As a NOR gate is a universal gate then we are
able to demonstrate that a simulated light sensitive BZ medium exhibits
computational universality
Investigation of the semiochemicals of confused flour beetle Tribolium confusum Jaquelin du Val and grain weevil Sitophilus granarius (L.) in stored wheat grain and flour
This investigation sets out to identify specific volatile compounds from both flour infested with the confused flour beetle, Tribolium confusum and wheat grain infested with the grain weevil, Sitophilus granarius. These volatiles could help to aid the early detection of infestation by these pests. Volatiles by the infestation of these insect pests were entrained and analysed using Solid-Phase Micro-Extraction (SPME) coupled with gas chromatography-mass spectrometry (GCMS). Several volatile compounds were identified specific to T. confusum and S. granarius, including the known semiochemicals of T. confusum. The T. confusum larvae specifically emitted the volatiles 1-octen-3-one, benzeneacetaldehyde and decanal, whilst the adults specifically emitted the volatiles 2-methyl and 2- ethyl-1,3-benzenediols, the known semiochemicals 1-pentadecene, 2-methyl and 2-ethyl-1,4- benzoquinones and a series of yet to be fully identified unsaturated hydrocarbons. Both T. confusum adults and larvae emitted 2-methylbutanal and 2-butanone. Furthermore, four volatiles were identified unique to flour infested by T. confusum, 3-penten-2-one, 3-octanone, 2-octenal and 2-butyl-1-octanol. The S. granarius adults specifically emitted the volatiles 2-methylpropanoic acid and 3-methylbutanoic acid, whilst infested wheat grain produced the following volatile organic compounds, 2-methylfuran, 2- ethylfuran, 2-methyl-1-butanol, 2-ethyl-2-pentenal and 2,5-dimethylpyrazine. We believe these specific volatiles may act as semiochemicals for these insects and could aid in semiochemical monitoring for the early detection of infestation by these insects.Keywords: Tribolium confusum, Sitophilus granarius, GC-MS, SPME, Semiochemicals
RC J0311+0507: A Candidate for Superpowerful Radio Galaxies in the Early Universe at Redshift z=4.514
A strong emission line at 6703A has been detected in the optical spectrum for
the host galaxy (R=23.1) of the radio source RC J0311+0507 (4C+04.11). This
radio galaxy, with a spectral index of 1.31 in the frequency range 365-4850
MHz, is one of the ultrasteep spectrum objects from the deep survey of a sky
strip conducted with RATAN-600 in 1980-1981. We present arguments in favor of
the identification of this line with Ly\alpha at redshift z=4.514. In this
case, the object belongs to the group of extremely distant radio galaxies of
ultrahigh radio luminosity (P_{1400}=1.3 x 10^{29}W Hz^{-1}). Such power can be
provided only by a fairly massive black hole (~10^9M_\sun}) that formed in a
time less than the age of the Universe at the observed z(1.3 Gyr) or had a
primordial origin.Comment: 8 pages, 3 figure
Editorial: The use of volatile compounds analysis for the assessment of food and beverage quality
A study of volatile compounds in the breath of children with type 1 diabetes
A pilot study of exhaled volatile compounds and their correlation with blood glucose levels in eight children with type 1 diabetes is reported. Five paired blood and breath samples were obtained from each child over a 6 hour period. The blood glucose concentration ranged from 41.4 to 435.6 mg/dL. Breath samples were collected in Tedlar bags and immediately evacuated through thermal desorption tubes packed with Carbopack B and C. The VOCs were later recovered by thermal desorption and analysed using gas chromatography mass spectrometry. The study identified 74 volatile compounds present in at least 10% of the patient samples. Of these 74 volatiles 36 were found in all patient samples tested. Further analysis of the 36 compounds found that none showed significant overall correlation with blood glucose levels. Isoprene showed a weak negative correlation with blood glucose levels. Acetone was found to have no correlation with blood glucose levels for the patients studied. Some patients showed significant individual correlation between the relative peak areas of certain compounds and blood glucose levels. However, there was no consistent pattern observed within these results across all 8 patients. Additional breath samples were collected in Tedlar bags and analysed using SIFTMS for 3 of the patients and a healthy control. The levels of 24 volatiles are reported and were found to be generally consistent with previously reported SIFT-MS data. In agreement with the GCMS data, no compounds exhibited a significant overall correlation with blood glucose level
Mid-Infrared Spectra of High Redshift (z>2) Radio Galaxies
We present the first mid-infrared Spitzer/Infrared Spectrograph (IRS)
observations of powerful radio galaxies at z>2. These radio galaxies, 4C +23.56
(z=2.48) and 6C J1908+7220 (z=3.53), both show strong mid-infrared continua,
but with 6C J1908+7220 also showing strong PAH emission at rest-frame 6.2 and
7.7um. In 4C+23.56 we see no obvious PAH features above the continuum. The PAH
emission in 6C J1908+7220 is the amongst the most distant observed to date and
implies that there is a large instantaneous star formation rate (SFR). This is
consistent with the strong detection of 6C J1908+7220 at far-IR and sub-mm
wavelengths, indicative of large amounts of cold dust, ~10^9Msun. Powerful
radio galaxies at lower redshifts tend to have weak or undetectable PAH
features and typically have lower far-IR luminosities. In addition, 4C 23.56
shows moderate silicate absorption as seen in less luminous radio galaxies,
indicating tau_{9.7um}=0.3+/-0.05. This feature is shifted out of the observed
wavelength range for 6C J1908+7220. The correlation of strong PAH features with
large amounts of cold dust, despite the presence of a powerful AGN, is in
agreement with other recent results and implies that star formation at high
redshift is, in some cases at least, associated with powerful, obscured AGN.Comment: 6 pages, 3 figures, includes emulateapj.cls, in press ApJ
Is there a mass discrepancy in the Cepheid binary OGLE-LMC-CEP0227?
Context. The Cepheid mass discrepancy, the difference between masses
predicted from stellar evolution and stellar pulsation calculations, is a
challenge for the understanding of stellar astrophysics. Recent models of the
eclipsing binary Cepheid OGLE-LMC-CEP-0227 have suggested that the discrepancy
may be resolved. Aims. We explore for what physical parameters do stellar
evolution models agree with the measured properties of OGLE-LMC-CEP0227 and
compare to canonical stellar evolution models assuming no convective core
overshooting. Methods. We construct state-of-the-art stellar evolution models
for varying mass, metallicity, and convective core overshooting and compare the
stellar evolution predictions with the observed properties. Results. The
observed mass, effective temperature, and radius of the two stars in the binary
system are well fit by numerous combinations of physical parameters, suggesting
a Cepheid mass discrepancy of 10-20% relative to canonical stellar evolution
models. Conclusions. The properties of the observed binary Cepheid suggest that
the Cepheid mass discrepancy is still a challenge and requires more specific
observations, such as the rate of period change, to better constrain and
understand the necessary physics for stellar evolution models to resolve the
discrepancy.Comment: 5 pages, 3 figures, A&A accepte
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