1,180 research outputs found
The Bok Globule BHR 160: structure and star formation
BHR 160 is a virtually unstudied cometary globule within the Sco OB4
association in Scorpius at a distance of 1600pc. It is part of a system of
cometary clouds which face the luminous O star HD155806. BHR 160 is special
because it has an intense bright rim. We attempt to derive physical parameters
for BHR 160 and to understand its structure and the origin of its peculiar
bright rim. BHR 160 was mapped in the CO, CO and CO (2-1)
and (1-0) and CS (3-2) and (2-1) lines. These data, augmented with stellar
photometry derived from the ESO VVV survey, were used to derive the mass and
distribution of molecular material in BHR 160 and its surroundings. Archival
mid-infrared data from the WISE satellite was used to find IR excess stars in
the globule and its neighbourhood. An elongated 1' by 0.6' core lies adjacent
to the globule bright rim. CO emission covers the whole globule, but the
CO, CO and CS emission is more concentrated to the core. The
CO line profiles indicate the presence of outflowing material near the
core, but the spatial resolution of the mm data is not sufficient for a
detailed spatial analysis. The BHR 160 mass estimated from the CO
mapping is 10050Msun(d/1.6kpc) where d is the distance to the globule.
Approximately 70 percent of the mass lies in the dense core. The total mass of
molecular gas in the direction of BHR 160 is 210(d/1.6kpc) Msun when
estimated from the more extended VVV NIR photometry. We argue that the bright
rim of BHR 160 is produced by a close-by early B-type star, HD 319648, that was
likely recently born in the globule. This star is likely to have triggered the
formation of a source, IRS 1, that is embedded within the core of the globule
and detected only in Ks and by WISE and IRAS.Comment: 19 pages, 24 figures, Accepted for publication in Astronomy and
Astrophysic
Braiding Interactions in Anyonic Quantum Walks
The anyonic quantum walk is a dynamical model describing a single anyon
propagating along a chain of stationary anyons and interacting via mutual
braiding statistics. We review the recent results on the effects of braiding
statistics in anyonic quantum walks in quasi-one dimensional ladder geometries.
For anyons which correspond to spin-1/2 irreps of the quantum groups ,
the non-Abelian species gives rise to entanglement between the
walker and topological degrees of freedom which is quantified by quantum link
invariants over the trajectories of the walk. The decoherence is strong enough
to reduce the walk on the infinite ladder to classical like behaviour. We also
present numerical results on mixing times of or Ising model anyon
walks on cyclic graphs. Finally, the possible experimental simulation of the
anyonic quantum walk in Fractional Quantum Hall systems is discussed.Comment: 13 pages, submitted to Proceedings of the 2nd International
Conference on Theoretical Physics (ICTP 2012
Investigation of Visual Management Cases in Construction by an Analytical Framework from Manufacturing
Along with the progress of globalization, speed and efficiency have become more critical for any industry than ever before. In this sense, the concept and methods of lean management, promoting these performances, have been deployed from manufacturing, its origin industry, to other industries. This paper deals with this management style in the construction industry, called lean construction. In particular, visual management (VM) as one effective tool in this scheme is focused on. A number of VM cases, 306 in total, was collected from both construction and manufacturing sites and investigated by the so-called 5W1H analytical framework developed in the manufacturing industry. Obtained results suggest that the VM cases in construction have common attributes such as purpose and location, target to attain, users’ attributes, timing to use and elemental technologies for case development. A comparison analysis of the VM cases from construction and those from manufacturing was also carried out, for a mutual transfer of this technology between these industries
Mass and motion of globulettes in the Rosette Nebula
We have investigated tiny molecular clumps in the Rosette Nebula. Radio
observations were made of molecular line emission from 16 globulettes
identified in a previous optical survey. In addtion, we collected images in the
NIR broad-band JHKs and narrow-band Paschen beta and H2. Ten objects, for which
we collected information from several transitions in 12CO and 13CO were
modelled using a spherically symmetric model. The best fit to observed line
ratios and intensities was obtained by assuming a model composed of a cool and
dense centre and warm and dense surface layer. The average masses derived range
from about 50 to 500 Jupiter masses, which is similar to earlier estimates
based on extinction measures. The globulettes selected are dense, with very
thin layers of fluorescent H2 emission. The NIR data shows that several
globulettes are very opaque and contain dense cores. Because of the high
density encountered already at the surface, the rims become thin, as evidenced
by our P beta images.
We conclude that the entire complex of shells, elephant trunks, and
globulettes in the northern part of the nebula is expanding with nearly the
same velocity of ~22 km/s, and with a very small spread in velocity among the
globulettes. Some globulettes are in the process of detaching from elephant
trunks and shells, while other more isolated objects must have detached long
ago and are lagging behind in the general expansion of the molecular shell. The
suggestion that some globulettes might collapse to form planetary-mass objects
or brown dwarfs is strengthened by our finding of dense cores in several
objects.Comment: 15 pages, 15 figures Astronomy and Astrophysics 201
NASA CA Operations Devolution: Status Update
What is Devolution? Devolution is a spreading of CA (Conjunction Assessment) operations responsibilities to mission FOTs (Flight Operations Teams): Permits efficiencies in handling the increased workload caused by Space Fence and large constellations; Missions given more flexibility in choosing specific approach to CA requirements that resonates best with their particular needs; CARA (Conjunction Assessment Risk Analysis) retains Agency oversight through an established NASA Standard - will establish requirements for devolved CA preparations, processing, and operations conduct. Devolution is a PROPOSED paradigm under consideration by SMD (Space Missions Directorate): Number of activities required before Agency-level decision can be rendered; Agency requirements established via approved CA Standard; Operational experience testimony from two separate pilot programs; After these activities complete, decision will be made whether devolution is a feasible option for missions; CARA is recommending devolution to exist as an option for missions
Statistical dynamics of a non-Abelian anyonic quantum walk
We study the single particle dynamics of a mobile non-Abelian anyon hopping
around many pinned anyons on a surface. The dynamics is modelled by a discrete
time quantum walk and the spatial degree of freedom of the mobile anyon becomes
entangled with the fusion degrees of freedom of the collective system. Each
quantum trajectory makes a closed braid on the world lines of the particles
establishing a direct connection between statistical dynamics and quantum link
invariants. We find that asymptotically a mobile Ising anyon becomes so
entangled with its environment that its statistical dynamics reduces to a
classical random walk with linear dispersion in contrast to particles with
Abelian statistics which have quadratic dispersion.Comment: 7 pages, 5 figure
A Single Conjunction Risk Assessment Metric: the F-Value
The Conjunction Assessment Team at NASA Goddard Space Flight Center provides conjunction risk assessment for many NASA robotic missions. These risk assessments are based on several figures of merit, such as miss distance, probability of collision, and orbit determination solution quality. However, these individual metrics do not singly capture the overall risk associated with a conjunction, making it difficult for someone without this complete understanding to take action, such as an avoidance maneuver. The goal of this analysis is to introduce a single risk index metric that can easily convey the level of risk without all of the technical details. The proposed index is called the conjunction "F-value." This paper presents the concept of the F-value and the tuning of the metric for use in routine Conjunction Assessment operations
Achieving Successful Outcomes In a TeleIntervention Program
For well over a decade, family-centered early intervention services have been delivered through models of teleintervention (TI) to children who are Deaf and Hard of Hearing (DHH) and their families. Ongoing outcome data continue to demonstrate the viability, effectiveness, and positive impacts these services provide to both the service providers and the families served. However, to establish a successful TI program, careful planning is required, and barriers and potential roadblocks must be reduced or eliminated. When these challenges are adequately addressed, TI programs are more likely to achieve its primary goal of delivering appropriate family-centered early intervention
Training the Next Generation of Practitioners In Early Intervention and Telepractice: Three University Models
The COVID-19 pandemic continues to shape the provision of family-centered early intervention services for children who are Deaf or Hard-of-Hearing and their families. In programs, schools, and centers, direct in-person contact with families have been significantly curtailed as a means to limit the exposure to and spead of the virus. Emergency remote learning has lead to an increase in telepractice, also referred to as teleintervention, as the designated model of service provision. Most early interventionists, speech-language pathologists, and teachers of the Deaf were not sufficiently trained to suddenly implement emergency remote teaching or telepractice services, but service providers had no option but to forge ahead, often with limited or no prior knowledge and experience with the provision of services using only telecommunications technology. Fortunately, however, some university training programs have integrated telepractice into their curricula and practica experiences for many years, and three of those programs are profiled here
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