662 research outputs found
A Large-scale CO Imaging of the Galactic Center. II. Dynamical Properties of Molecular Clouds
The data from the Nobeyama Radio Observatory 45 m telescope Galactic Center
CO survey have been analyzed to generate a compilation of molecular clouds with
intense CO emission in this region. Clouds are identified in an automated
manner throughout the main part of the survey data for all CO emission peaks
exceeding 10 K (). Correlations between the size, velocity dispersion,
virial mass, and the CO luminosity, for the molecular clouds in the Galactic
center were shown. We diagnosed gravitational stabilities of identified clouds
assuming that the disk clouds are nearly at the onset of gravitational
instability. Most of the clouds and cloud complexes in the Galactic center are
gravitationally stable, while some clouds with intense CO emission are
gravitationally unstable.Comment: 4 pages, 4 figures, to appear in the Proceedings of the 32nd COSPAR
Scientific Assembl
Fractional Fourier Transform- Simulations and experimental results
Cataloged from PDF version of article.Recently two optical interpretations of the fractional Fourier transform operator were introduced. We
address implementation issues of the fractional-Fourier-transform operation. We show that the original
bulk-optics configuration for performing the fractional-Fourier-transform operation 3J. Opt. Soc. Am. A
10, 2181 1199324 provides a scaled output using a fixed lens. For obtaining a non-scaled output, an
asymmetrical setup is suggested and tested. For comparison, computer simulations were performed.
A good agreement between computer simulations and experimental results was obtained
Anamorphic Fractional Fourier Transforming--Optical Implementation and Applications
Cataloged from PDF version of article.An additional degree of freedom is introduced to fractional-Fourier-transform systems by use of anamorphic optics. A different fractional Fourier order along the orthogonal principal directions is performed. A laboratory experimental system shows preliminary results that demonstrate the proposed theory. Applications such as anamorphic fractional correlation and multiplexing in fractional domains are briefly suggested. (C) 1995 Optical Society of Americ
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Electrophysiological Evidence of Attentional Biases in Social Anxiety Disorder
Background: Previous studies investigating attentional biases in social anxiety disorder (SAD) have yielded mixed results. Recent event-related potential (ERP) studies using the dot-probe paradigm in non-anxious participants have shown that the P1 component is sensitive to visuospatial attention towards emotional faces. We used a dot-probe task in conjunction with high-density ERPs and source localization to investigate attentional biases in SAD.
Method: Twelve SAD and 15 control participants performed a modified dot-probe task using angry–neutral and happy–neutral face pairs. The P1 component elicited by face pairs was analyzed to test the hypothesis that SAD participants would display early hypervigilance to threat-related cues. The P1 component to probes replacing angry, happy or neutral faces was used to evaluate whether SAD participants show either sustained hypervigilance or decreased visual processing of threat-related cues at later processing stages.
Results: Compared to controls, SAD participants showed relatively (a) potentiated P1 amplitudes and fusiform gyrus (FG) activation to angry–neutral versus happy–neutral face pairs; (b) decreased P1 amplitudes to probes replacing emotional (angry and happy) versus neutral faces; and (c) higher sensitivity (d′) to probes following angry–neutral versus happy–neutral face pairs. SAD participants also showed significantly shorter reaction times (RTs) to probes replacing angry versus happy faces, but no group differences emerged for RT.
Conclusions: The results provide electrophysiological support for early hypervigilance to angry faces in SAD with involvement of the FG, and reduced visual processing of emotionally salient locations at later stages of information processing, which might be a manifestation of attentional avoidance.Psycholog
A computational analysis of lower bounds for big bucket production planning problems
In this paper, we analyze a variety of approaches to obtain lower bounds for multi-level production planning problems with big bucket capacities, i.e., problems in which multiple items compete for the same resources. We give an extensive survey of both known and new methods, and also establish relationships between some of these methods that, to our knowledge, have not been presented before. As will be highlighted, understanding the substructures of difficult problems provide crucial insights on why these problems are hard to solve, and this is addressed by a thorough analysis in the paper. We conclude with computational results on a variety of widely used test sets, and a discussion of future research
Case Report:Leprosy Osteoarticular Alterations Mimicking Rheumatoid Arthritis
Deformities of bones of the face and extremities are markers of leprosy (Hansen’s disease) which contribute to stigma associated with this disease. Among these deformities are articular alterations that can mimic rheumatoid arthritis (RA). In this case, a 64-year-old man presented with a history of having been treated for lepromatous leprosy and erythema nodosum leprosum episodes, which evolved with joint alterations similar to those of RA. Most cases of leprosy-related arthritis are associated with reactional episodes, of which a large number do not respond to conventional therapy for leprosy reactions. In cases of chronic arthritis not associated with leprosy reactions, although patients show considerable relief with anti-leprosy therapy, arthritis is not completely resolved. This emphasizes the need for early diagnosis and treatment of leprosy to prevent the development of osteoarticular alterations
A Mixed-Integer Linear Programming Model for Transportation Planning in the Full Truck Load Strategy to Supply Products with Unbalanced Demand in the Just in Time Context: A Case Study
[EN] Growing awareness in cutting transport costs and minimizing the environmental impact means that companies are increasingly interested in using the full truck load strategy in their supply tasks. This strategy consists of filling trucks completely with one product type or a mixture of products from the same supplier. This paper aims to propose a mixed-integer linear programming model and procedure to fill trucks which considers limitations of stocks, stock levels and unbalanced demand and minimization of the total number of trucks used in the full truck load strategy. The results obtained from a case study are presented and are exported in a conventional spreadsheet available for a company in the automotive industry.Maheut ., JP.; García Sabater, JP. (2013). A Mixed-Integer Linear Programming Model for Transportation Planning in the Full Truck Load Strategy to Supply Products with Unbalanced Demand in the Just in Time Context: A Case Study. IFIP Advances in Information and Communication Technology. 397:576-583. doi:10.1007/978-3-642-40361-3_73S576583397Bitran, G.R., Haas, E.A., Hax, A.C.: Hierarchical production planning: a single stage system. Operations Research 29, 717–743 (1981)Sun, H., Ding, F.Y.: Extended data envelopment models and a practical tool to analyse product complexity related to product variety for an automobile assembly plant. International Journal of Logistics Systems and Management 6, 99–112 (2010)Boysen, N., Fliedner, M.: Cross dock scheduling: Classification, literature review and research agenda. Omega 38, 413–422 (2010)Garcia-Sabater, J.P., Maheut, J., Garcia-Sabater, J.J.: A two-stage sequential planning scheme for integrated operations planning and scheduling system using MILP: the case of an engine assembler. Flexible Services and Manufacturing Journal 24, 171–209 (2012)Ben-Khedher, N., Yano, C.A.: The Multi-Item Replenishment Problem with Transportation and Container Effects. Transportation Science 28, 37–54 (1994)Cousins, P.D.: Supply base rationalisation: myth or reality? European Journal of Purchasing Supply Management 5, 143–155 (1999)Kiesmüller, G.P.: A multi-item periodic replenishment policy with full truckloads. International Journal of Production Economics 118, 275–281 (2009)Goetschalckx, M.: Transportation Systems Supply Chain Engineering, vol. 161, pp. 127–154. Springer, US (2011)Liu, R., Jiang, Z., Fung, R.Y.K., Chen, F., Liu, X.: Two-phase heuristic algorithms for full truckloads multi-depot capacitated vehicle routing problem in carrier collaboration. Computers Operations Research 37, 950–959 (2010)Arunapuram, S., Mathur, K., Solow, D.: Vehicle Routing and Scheduling with Full Truckloads. Transportation Science 37, 170–182 (2003
Spectral imaging of the Central Molecular Zone in multiple 3-mm molecular lines
We have mapped 20 molecular lines in the Central Molecular Zone (CMZ) around
the Galactic Centre, emitting from 85.3 to 93.3 GHz. This work used the 22-m
Mopra radio telescope in Australia, equipped with the 8-GHz bandwidth UNSW-MOPS
digital filter bank, obtaining \sim 2 km/s spectral and \sim 40 arcsec spatial
resolution. The lines measured include emission from the c-C3H2, CH3CCH, HOCO+,
SO, H13CN, H13CO+, SO, H13NC, C2H, HNCO, HCN, HCO+, HNC, HC3N, 13CS and N2H+
molecules. The area covered is Galactic longitude -0.7 to 1.8 deg. and latitude
-0.3 to 0.2 deg., including the bright dust cores around Sgr A, Sgr B2, Sgr C
and G1.6-0.025. We present images from this study and conduct a principal
component analysis on the integrated emission from the brightest 8 lines. This
is dominated by the first component, showing that the large-scale distribution
of all molecules are very similar. We examine the line ratios and optical
depths in selected apertures around the bright dust cores, as well as for the
complete mapped region of the CMZ. We highlight the behaviour of the bright
HCN, HNC and HCO+ line emission, together with that from the 13C isotopologues
of these species, and compare the behaviour with that found in extra-galactic
sources where the emission is unresolved spatially. We also find that the
isotopologue line ratios (e.g. HCO+/H13CO+) rise significantly with increasing
red-shifted velocity in some locations. Line luminosities are also calculated
and compared to that of CO, as well as to line luminosities determined for
external galaxies.Comment: 27 pages, 15 figures, 12 tables, accepted by MNRA
Kinetic temperatures toward X1/X2 orbit interceptions regions and Giant Molecular Loops in the Galactic center region
Context: It is well known that the kinetic temperatures, Tkin, of the
molecular clouds in the Galactic center region are higher than in typical disk
clouds. However, the Tkin of the molecular complexes found at higher latitudes
towards the giant molecular loops in the central region of the Galaxy is so far
unknown. The gas of these high latitude molecular clouds (hereafter referred to
as halo clouds) is located in a region where the gas in the disk may interact
with the gas in the halo in the Galactic center region.
Aims: To derive Tkin in the molecular clouds at high latitude and understand
the physical process responsible for the heating of the molecular gas both in
the Central Molecular Zone (the concentration of molecular gas in the inner 500
pc) and in the giant molecular loops.
Methods: We measured the metastable inversion transitions of NH3 from (1,1)
to (6,6) toward six positions selected throughout the Galactic central disk and
halo. We used rotational diagrams and large velocity gradient modeling to
estimate the kinetic temperatures toward all the sources. We also observed
other molecules like SiO, HNCO, CS, C34S, C18O, and 13CO, to derive the
densities and to trace different physical processes (shocks, photodissociation,
dense gas) expected to dominate the heating of the molecular gas.
Results: We derive for the first time Tkin of the high latitude clouds
interacting with the disk in the Galactic center region. We find high
rotational temperatures in all the observed positions. We derive two kinetic
temperature components (150 K and 40 K) for the positions in the Central
Molecular Zone, and only the warm kinetic temperature component for the clouds
toward the giant molecular loops. The fractional abundances derived from the
different molecules suggest that shocks provide the main heating mechanism
throughout the Galactic center, also at high latitudesComment: accepted for publication in A&A 06/09/201
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