8,255 research outputs found
Star Formation in the Trifid Nebula
We have obtained maps of the 1.25mm thermal dust emission and the molecular
gas emission over a region of 20' by 10' arcmin around the Trifid Nebula (M20),
with the IRAM 30m and the CSO telescopes as well as in the mid-infrared
wavelength with ISO and SPITZER. Our survey is sensitive to features down to
N(H2) \sim 10^{22} cm-2 in column density. The cloud material is distributed in
fragmented dense gas filaments (n(H2) \sim 1000 cm-3) with sizes ranging from 1
to 10 pc. A massive filament, WF, with properties typical of Infra Red Dark
Clouds, connects M20 to the W28 supernova remnant. These filaments pre-exist
the formation of the Trifid and were originally self-gravitating. The fragments
produced are very massive (100 Msun or more) and are the progenitors of the
cometary globules observed at the border of the HII region. We could identify
33 cores, 16 of which are currently forming stars. They are usually
gravitationally unbound and have low masses of a few Msun. The densest starless
cores (several 10^5 cm-3) may be the site for the next generation of stars. The
physical gas and dust properties of the cometary globules have been studied in
detail and have been found very similar. They all are forming stars. Several
intermediate-mass protostars have been detected in the cometary globules and in
the deeply embedded cores. Evidence of clustering has been found in the shocked
massive cores TC3-TC4-TC5. M20 is a good example of massive-star forming region
in a turbulent, filamentary molecular cloud. Photoionization appears to play a
minor role in the formation of the cores. The observed fragmentation is well
explained by MHD-driven instabilities and is usually not related to M20. We
propose that the nearby supernova remnant W28 could have triggered the
formation of protostellar clusters in nearby dense cores of the Trifid.Comment: 16 pages, 24 figures, 5 Tables To appear in Astronomy and
Astrophysic
Score-Informed Source Separation for Musical Audio Recordings [An overview]
(c) 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works
Electron Confinement, Orbital Ordering, and Orbital Moments in - Oxide Heterostructures
The (SrTiO)/(SrVO) multilayer system is studied
with first principles methods through the observed insulator-to-metal
transition with increasing thickness of the SrVO layer. When correlation
effects with reasonable magnitude are included, crystal field splittings from
the structural relaxations together with spin-orbit coupling (SOC) determines
the behavior of the electronic and magnetic structures. These confined slabs of
SrVO prefer =() orbital ordering of and
() orbitals within the plane, accompanied by
=(0,0) spin order (ferromagnetic alignment). The result is a
SOC-driven ferromagnetic Mott insulator. The orbital moment of 0.75
strongly compensates the spin moment on the sublattice. The
insulator-metal transition for (occurring between =4 and
=5) is reproduced. Unlike in the isoelectronic TiO/VO
(rutile structure) system and in spite of some similarities in orbital
ordering, no semi-Dirac point [{\it Phys. Rev. Lett.} {\bf 102}, 166803 (2009)]
is encountered, but the insulator-to-metal transition occurs through a
different type of unusual phase. For n=5 this system is very near (or at) a
unique semimetallic state in which the Fermi energy is topologically determined
and the Fermi surface consists of identical electron and hole Fermi circles
centered at =0. The dispersion consists of what can be regarded as a
continuum of radially-directed Dirac points, forming a "Dirac circle".Comment: 9 pages, 8 figure
Modularity from Fluctuations in Random Graphs and Complex Networks
The mechanisms by which modularity emerges in complex networks are not well
understood but recent reports have suggested that modularity may arise from
evolutionary selection. We show that finding the modularity of a network is
analogous to finding the ground-state energy of a spin system. Moreover, we
demonstrate that, due to fluctuations, stochastic network models give rise to
modular networks. Specifically, we show both numerically and analytically that
random graphs and scale-free networks have modularity. We argue that this fact
must be taken into consideration to define statistically-significant modularity
in complex networks.Comment: 4 page
Interventions for promoting reintegration and reducing harmful behaviour and lifestyles in street-connected children and young people (Review)
Background
Millions of street-connected children and young people worldwide live or work in street environments. They are vulnerable to many risks, whether or not they remain connected to families of origin, and despite many strengths and resiliencies, they are excluded from mainstream social structures and opportunities.
Objectives
Primary research objectives
To evaluate and summarise the effectiveness of interventions for street-connected children and young people that aim to:
⢠promote inclusion and reintegration;
⢠increase literacy and numeracy;
⢠facilitate access to education and employment;
⢠promote mental health, including self esteem;
⢠reduce harms associated with early sexual activity and substance misuse.
Secondary research objectives
⢠To explore whether effects of interventions differ within and between populations, and whether an equity gradient influences theseeffects, by extrapolating from all findings relevance for low- and middle-income countries (LMICs) (Peters 2004).
⢠To describe other health, educational, psychosocial and behavioural effects, when appropriate outcomes are reported.
⢠To explore the influence of context in design, delivery and outcomes of interventions.
Interventions for promoting reintegration and reducing harmful behaviour and lifestyles in street-connected children and young people 1
(Review)
Copyright Š 2016 The Cochrane Collaboration. Published by John Wiley & Sons, Ltd.
To explore the relationship between numbers of components and duration and effects of interventions.
⢠To highlight implications of these findings for further research and research methods to improve evidence in relation to the primary
research objective.
⢠To consider adverse or unintended outcomes.
Search methods
We searched the following bibliographic databases, searched for the original review, from inception to 2012, and various relevant non-governmental and organisational websites: Cochrane Central Register of Controlled Trials (CENTRAL); MEDLINE and PreMEDLINE;EMBASE and EMBASE Classic; Cumulative Index to Nursing and Allied Health Literature (CINAHL); PsycINFO; Education Resource Information Center (ERIC); Sociological Abstracts; Social Services Abstracts; Social Work Abstracts; Healthstar; Latin American Caribbean Health Sciences Literature (LILACS); System for Grey literature in Europe (OpenGrey); ProQuest Dissertations and Theses; EconLit; IDEAS Economics and Finance Research; JOLIS Library Catalog of the holdings of the World Bank Group and International Monetary Fund (IMF) Libraries; British Library for Development Studies (BLDS); Google and Google Scholar. We
updated the search in April 2015 for the review update, using the same methods.
Selection criteria
This review includes data from harm reduction or reintegration intervention studies that used a comparison group study design; all were randomised or quasi-randomised studies. Studies were included if they evaluated interventions provided for street-connected children and young people, from birth to 24 years, in all contexts.
Data collection and analysis
Two review authors independently extracted data and assessed risk of bias and other factors presented in the Discussion and Summary quality assessment (Grades of Recommendation, Assessment, Development and Evaluation (GRADE)). We extracted data on intervention delivery, context, process factors, equity and outcomes, and grouped outcomes into psychosocial outcomes, risky sexual behaviours or substance use. We conducted meta-analyses for outcomes where the outcome measures were sufficiently similar. We evaluated other outcomes narratively.
Main results
We included 13 studies evaluating 19 interventions from high-income countries (HICs). We found no sufficiently robust evaluations conducted in low- and middle-income countries (LMICs). Study quality overall was low and measurements used by studies variable. Participants were classified as drop-in and shelter-based. No studies measured the primary outcome of reintegration and none reported on adverse effects.We found no consistent results on a range of relevant outcomes within domains of psychosocial health, substance misuse and sexually risky behaviours . Interventions evaluated consisted of time-limited therapeutically based programmes that proved no more effective than standard shelter or drop-in services and other control interventions used for most outcomes in most studies.
Favourable changes from baseline were reported for outcomes for most participants following therapy interventions and standard services. We noted considerable heterogeneity between studies and inconsistent reporting of equity data. No studies measured the primary outcome of reintegration or reported on adverse effects.
Authorsâ conclusions
Analysis revealed no consistently significant benefit for focused therapeutic interventions compared with standard services such as dropin centres, case management and other comparable interventions for street-connected children and young people. Commonly available services, however, were not rigorously evaluated. Robust evaluation of interventions, including comparison with no intervention, would establish a more reliable evidence base to inform service implementation. More robust research is needed in LMICs to examine interventions for street-connected children and young people with different backgrounds and service needs
Theoretical and experimental study of AC loss in HTS single pancake coils
The electromagnetic properties of a pancake coil in AC regime as a function
of the number of turns is studied theoretically and experimentally.
Specifically, the AC loss, the coil critical current and the voltage signal are
discussed. The coils are made of Bi2Sr2Ca2Cu3O10/Ag (BiSCCO) tape, although the
main qualitative results are also applicable to other kinds of superconducting
tapes, such as coated conductors. The AC loss and the voltage signal are
electrically measured using different pick up coils with the help of a
transformer. One of them avoids dealing with the huge coil inductance. Besides,
the critical current of the coils is experimentally determined by conventional
DC measurements. Furthermore, the critical current, the AC loss and the voltage
signal are simulated, showing a good agreement with the experiments. For all
simulations, the field dependent critical current density inferred from DC
measurements on a short tape sample is taken into account.Comment: 22 pages, 15 figures; contents extended (sections 3.2 and 4); one new
figure (figure 5) and two figures replaced (figures 3 and 8); typos
corrected; title change
High-J v=0 SiS Maser Emission in IRC+10216: A New Case of Infrared Overlaps
We report on the first detection of maser emission in the J=11-10, J=14-13
and J=15-14 transitions of the v=0 vibrational state of SiS toward the C-rich
star IRC+10216. These masers seem to be produced in the very inhomogeneous
region between the star and the inner dust formation zone, placed at 5-7 R*,
with expansion velocities below 10 km/s. We interpret the pumping mechanism as
due to overlaps between v=1-0 ro-vibrational lines of SiS and mid-IR lines of
C2H2, HCN and their 13C isotopologues. The large number of overlaps found
suggests the existence of strong masers for high-J v=0 and v=1 SiS transitions,
located in the submillimeter range. In addition, it could be possible to find
several rotational lines of the SiS isotopologues displaying maser emission.Comment: 4 pages, 1 figure, published in the ApJ Letter
Thermal Conductivity of Partially Graphitized Biocarbon Obtained by Carbonization of Medium-Density Fiberboard in the Presence of a Ni-Based Catalyst
The thermal conductivity k and resistivity Ď of biocarbon matrices, prepared by carbonizing medium-density fiberboard at Tcarb = 850 and 1500°C in the presence of a Ni-based catalyst (samples MDFC( Ni)) and without a catalyst (samples MDF-C), have been measured for the first time in the temperature range of 5â300 K. X-ray diffraction analysis has revealed that the bulk graphite phase arises only at Tcarb = 1500°C. It has been shown that the temperature dependences of the thermal conductivity of samples MDFC- 850 and MDF-C-850(Ni) in the range of 80â300 K are to each other and follow the law of k(T) ~ T1.65, but the use of the Ni-catalyst leads to an increase in the thermal conductivity by a factor of approximately 1.5, due to the formation of a greater fraction of the nanocrystalline phase in the presence of the Ni-catalyst at Tcarb = 850°C. In biocarbon MDF-C-1500 prepared without a catalyst, the dependence is k(T) ~ T1.65, and it is controlled by the nanocrystalline phase. In MDF-C-1500(Ni), the bulk graphite phase formed increases the thermal conductivity by a factor of 1.5â2 compared to the thermal conductivity of MDF-C-1500 in the entire temperature range of 5â300 K; k(T = 300 K) reaches the values of ~10 W mâ1 Kâ1, characteristic of biocarbon obtained without a catalyst only at high temperatures of Tcarb = 2400°C. It has been shown that MDF-C-1500(Ni) in the temperature range of 40â300 K is characterized by the dependence, k(T) ~ T1.3, which can be described in terms of the model of partially graphitized biocarbon as a composite of an amorphous matrix with spherical inclusions of the graphite phaseRussian Foundation for Basic Research 14-03- 0049
On the representation of simple Riesz groups
In this paper we answer Open Problem 2 of Goodearl's book on
partially ordered abelian groups in the case of partially ordered sim-
ple groups. As a consequence, we obtain a version of the Theorem of
structure of dimension groups in the case of simple Riesz groups. Also,
we give a method for constructing torsion-free strictly perforated simple
Riesz groups of rank one, and we see that every dense additive subgroup
of Q can be obtained using this method
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