2,771 research outputs found
Direct and long-lasting effects elicited by repeated drug administration on 50-kHz ultrasonic vocalizations are regulated differently: Implications for the study of the affective properties of drugs of abuse
Several studies suggest that 50-kHz ultrasonic vocalizations (USVs) may indicate a positive affective state in rats, and these vocalizations are increasingly being used to investigate the properties of psychoactive drugs. Previous studies, however, have focused on dopaminergic psychostimulants and morphine, whereas little is known about how other drugs modulate 50-kHz USVs. To further elucidate the neuropharmacology of 50-kHz USVs, the present study characterized the direct and long-lasting effects of different drugs of abuse, by measuring the number of 50-kHz USVs and their 'trill' subtype emitted by adult male rats. Rats received repeated administrations of amphetamine (2 mg/kg, i.p.), 3,4-methylenedioxymethamphetamine (MDMA, 7.5 mg/kg, i.p.), morphine (7.5 mg/kg, s.c.), or nicotine (0.4 mg/kg, s.c.), on either consecutive or alternate days (five administrations in total) in a novel environment. Seven days later, rats were re-exposed to the drug-paired environment, subjected to USVs recording, and then challenged with the same drug. Finally, 7 d after the challenge, rats were repeatedly exposed to the drug-paired environment and vocalizations were measured. Amphetamine was the only drug to stimulate 50-kHz USVs and 'trill' subtype emission during administration and challenge. Conversely, all rats emitted 50-kHz USVs when re-exposed to the test cage, and this effect was most marked in morphine-treated rats, and less evident in nicotine-treated rats. This study demonstrates that the direct and long-lasting effects of drugs on 50-kHz USVs are regulated differently, providing a better understanding of the usefulness of these vocalizations in the study of psychoactive drugs
Self-propelled particles with fluctuating speed and direction of motion
We study general aspects of active motion with fluctuations in the speed and
the direction of motion in two dimensions. We consider the case in which
fluctuations in the speed are not correlated to fluctuations in the direction
of motion, and assume that both processes can be described by independent
characteristic time-scales. We show the occurrence of a complex transient that
can exhibit a series of alternating regimes of motion, for two different
angular dynamics which correspond to persistent and directed random walks. We
also show additive corrections to the diffusion coefficient. The characteristic
time-scales are also exposed in the velocity autocorrelation, which is a sum of
exponential forms.Comment: to appear in Phys. Rev. Let
Cross-reactivity among iodinated contrast agents: should we be concerned?
Background
Although several papers deal with "cross-reactivity" in patients with iodinated contrast medium (ICM) hypersensitivity reactions (HSRs), there is no in-depth knowledge of this phenomenon. To define ICM-groups as potential reaction partners and to identify any potential clinical relevance in patients with ICM-HSRs.
Methods
The literature database PubMed was searched for eligible papers dealing with ICM-allergy and "cross-reactivity". The data presented by the papers was analyzed and individual patient data was extracted for re-evaluation based on a definition for both 'polyvalent reactivity' and 'cross-reactivity' as well as for chemical structure-dependent ICM-groups.
Results
Twenty-five original papers (with n=340 extracted patients) formed the study population. Incidences of polyvalent reactivity were non-significantly higher than incidences of cross-reactivity (both range from 0% to 100%). Crossover evaluation in reaction pairings (culprit ICM A with ICM B versus culprit ICM B with ICM A) showed concordance of only 30%. Data support rather non-cross-reactivity (individual reaction pattern) than cross-reactivity constellations.
Conclusions
The obtained results favour an individual reaction pattern, rather than a reactivity driven by chemical structures and so-called cross-reactivity
An Information-Centric Platform for Social- and Location-Aware IoT Applications in Smart Cities
Recent advances in Smart City infrastructures and the Internet of Things represent a significant opportunity to improve people's quality of life. Corresponding research often focuses on Cloud-centric network architectures where sensor devices transfer collected data to the Cloud for processing. However, the formidable traffic generated by countless IoT devices and the need for low-latency services raise the need to move away from centralized architectures and bring the computation closer to the data sources. To this end, this paper discusses SPF, a middleware solution that supports IoT application development, deployment, and management. SPF runs IoT services on capable devices located at the network edge and proposes an information-centric programming model that takes advantage of decentralized computation resources located in the proximity of application users and data sources. SPF also adopts Value-of-Information based methods to prioritize the transmission of essential information
Polar bulges and polar nuclear discs: the case of NGC 4698
The early-type spiral NGC 4698 is known to host a nuclear disc of gas and
stars which is rotating perpendicularly with respect to the galaxy main disc.
In addition, the bulge and main disc are characterised by a remarkable
geometrical decoupling. Indeed they appear elongated orthogonally to each
other. In this work the complex structure of the galaxy is investigated by a
detailed photometric decomposition of optical and near-infrared images. The
intrinsic shape of the bulge was constrained from its apparent ellipticity, its
twist angle with respect to the major axis of the main disc, and the
inclination of the main disc. The bulge is actually elongated perpendicular to
the main disc and it is equally likely to be triaxial or axisymmetric. The
central surface brightness, scalelength, inclination, and position angle of the
nuclear disc were derived by assuming it is infinitesimally thin and
exponential. Its size, orientation, and location do not depend on the observed
passband. These findings support a scenario in which the nuclear disc is the
end result of the acquisition of external gas by the pre-existing triaxial
bulge on the principal plane perpendicular to its shortest axis and
perpendicular to the galaxy main disc. The subsequent star formation either
occurred homogeneously all over the extension of the nuclear disc or through an
inside-out process that ended more than 5 Gyr ago.Comment: 6 pages, 3 figures. Accepted for publication in MNRAS Letter
Accurate classification of 75 counterparts of objects detected in the 54 month Palermo Swift/BAT hard X-ray catalogue
Through an optical campaign performed at 4 telescopes located in the northern
and the southern hemispheres, we have obtained optical spectroscopy for 75
counterparts of unclassified or poorly studied hard X-ray emitting objects
detected with Swift/BAT and listed in the 54 month Palermo BAT catalogue. All
these objects have also observations taken with Swift/XRT, ROSAT or Chandra
satellites which allowed us to reduce the high energy error box and pinpoint
the most likely optical counterpart/s. We find that 69 sources in our sample
are Active Galactic Nuclei (AGNs); of them, 35 are classified as type 1 (with
broad and narrow emission lines), 33 are classified as type 2 (with only narrow
emission lines) and one is an high redshift QSO; the remaining 6 objects are
galactic cataclysmic variables (CVs). Among type 1 AGNs, 32 are objects of
intermediate Seyfert type (1.2-1.9) and one is Narrow Line Seyfert 1 galaxy;
for 29 out of 35 type 1 AGNs, we have been able to estimate the central black
hole mass and the Eddington ratio. Among type 2 AGNs, two display optical
features typical of the LINER class, 3 are classified as transition objects, 1
is a starburst galaxy and 2 are instead X-ray bright, optically normal
galaxies. All galaxies classified in this work are relatively nearby objects
(0.006 - 0.213) except for one at redshift 1.137.Comment: 19 pages, 5 figures, 6 tables, accepted for publications on Astronomy
and Astrophysics, main journal. arXiv admin note: text overlap with
arXiv:1206.509
Evaluation of the natural risk perception, awareness, and preparedness at school by means of ad hoc questionnaires
One of the Sendai Framework 2015-2030 targets is to reduce the disruption of basic services, like educational facilities. Disaster education is actually considered to be an important factor to promote disaster risk reduction. The school resilience is not related to a specific hazard and vulnerability, but it takes into account many factors, including the people’s natural risk perception and awareness, along with their knowledge and capability of how to behave in an emergency. The scientific literature provides various notions of risk, risk perception, risk awareness, and risk preparedness. The literature on children’s natural risk perception is scarce and very recent compared with that about adults. Indeed, children’s perceptions about nature and environment are truly different from those of adults. The available research mainly concerns the implementation of earthquake emergency measures, while not much is available on flood-risk perception and even less on landslides. The relationship between risk perception, awareness, and preparedness is widely studied, but once again, there is no unambiguous or unique result that depends on the approach and the context.
We decided to refine the questionnaire that contributes to assess the school-resilience employed in the Geo-hazard Safety Classification method (GSC). We designed 7 different questionnaires, one for the adult personnel and six for the students, taking into account the peculiarity of each age. These questionnaires were thought through and designed to investigate three main awareness fundamentals: i) knowledge of the correct behaviours and procedure during a natural emergency that occurs at school; ii) perception of the natural risk of the area where the school is located; and iii) general knowledge of the correct behaviours during a natural emergency at school.
Three different analyses were carried out on the 5899 filled in questionnaires (820 by personnel and 5079 by students of each school stage) distributed in 27 schools of Tuscany Region (Central Italy): a) school by school; b) questionnaire typology (i.e., different school age); and c) topics (awareness fundamentals i, ii, and iii) and questionnaire typology (i.e., different school age). The results are coherent and show that a) young children’s knowledge is perfectly adequate to their age, b) as the age and responsibilities increase, the awareness and preparation do not increase proportionally, and c) the competences of the school personnel are not sufficient, probably caused by critical issues emerged (i.e., it is not clear where family reunification must take place) and because the wrong hazard perception leads to underestimating the importance of prevention actions and disaster education and. This last outcome turns out to be unexpected.
These questionnaires are a suitable, quick, easy and low-cost tool, even if considered separately from the GSC method. The school head-masters or the local and national educational offices actually could use them a) to evaluate the geo-hydrological and seismic risk knowledge and awareness of students, professors and school personnel; b) to project and design actions needed to improve the school-resilience; c) to verify the goodness of the activities developed at point b); and d) as an educational tool to improve the disaster education
Unveiling the nature of INTEGRAL objects through optical spectroscopy. VII. Identification of 20 Galactic and extragalactic hard X-ray sources
Within the framework of our program of assessment of the nature of
unidentified or poorly known INTEGRAL sources, we present here spectroscopy of
optical objects, selected through positional cross-correlation with soft X-ray
detections (afforded with satellites such as Swift, ROSAT, Chandra and/or
XMM-Newton) as putative counterparts of hard X-ray sources detected with the
IBIS instrument onboard INTEGRAL. Using 6 telescopes of various sizes and
archival data from two on-line spectroscopic surveys we are able to identify,
either for the first time or independent of other groups, the nature of 20
INTEGRAL hard X-ray sources. Our results indicate that: 11 of these objects are
active galactic nuclei (AGNs) at redshifts between 0.014 and 0.978, 7 of which
display broad emission lines, 2 show narrow emission lines only, and 2 have
unremarkable or no emission lines (thus are likely Compton thick AGNs); 5 are
cataclysmic variables (CVs), 4 of which are (possibly magnetic) dwarf novae and
one is a symbiotic star; and 4 are Galactic X-ray binaries (3 with high-mass
companions and one with a low-mass secondary). It is thus again found that the
majority of these sources are AGNs or magnetic CVs, confirming our previous
findings. When possible, the main physical parameters for these hard X-ray
sources are also computed using the multiwavelength information available in
the literature. These identifications support the importance of INTEGRAL in the
study of the hard X-ray spectrum of all classes of X-ray emitting objects, and
the effectiveness of a strategy of multi-catalogue cross-correlation plus
optical spectroscopy to securely pinpoint the actual nature of unidentified
hard X-ray sources.Comment: 16 pages, 8 figures, 5 tables. Accepted for publication on Astronomy
& Astrophysics, main journal. Slight changes made to match the
proof-corrected version; references adde
High Field Studies of the Hidden Order Transition in URuSi
We studied in detail the low temperature/high magnetic field phases of
URuSi single crystals with specific heat, magnetocaloric effect,
and magnetoresistance in magnetic fields up to 45 T. Data obtained down to 0.5
K, and extrapolated to T = 0, show a suppression of the hidden order phase at
H(0) = 35.9 0.35 T and the appearance of a new phase for magnetic
fields in excess of H(0) = 36.1 0.35 T observed \textit{only} at
temperatures lower than 6 K. In turn, complete suppression of this high field
state is attained at a critical magnetic field H(0) = 39.7 0.35 T.
No phase transitions are observed above 40 T. We discuss our results in the
context of itinerant vs. localized \textit{f}-electron behavior and consider
the implications for the hidden order phase.Comment: 4 pages, 3 figures Submitted May 10, 2002. Revised Sep 17, 200
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