This study aims to investigate particle acceleration processes in the vicinity of the young massive stellar cluster Westerlund 1. Imaging of Cherenkov light from gamma -ray induced particle cascades ...in the Earth's atmosphere is used to search for VHE gamma rays from the region around Wd 1. Possible catalogued counterparts are searched for and discussed in terms of morphology and energetics of the HESS source. The detection of the degree-scale extended VHE gamma -ray source HESS J1646-458 is reported based on 45 h of HESS observations performed between 2004 and 2008. The VHE gamma -ray source is centred on the nominal position of Wd 1 and detected with a total statistical significance of similar to 20 sigma . Four objects coincident with HESS J1646-458 are discussed in the search of a counterpart, namely the magnetar CXOU J164710.2-455216, the X-ray binary 4U 1642-45, the pulsar PSR J1648-4611 and the massive stellar cluster Wd 1. In a single-source scenario, Wd 1 is favoured as site of VHE particle acceleration.
Design of an Agent-Based Traffic Control System Ojeniyi, Adegoke; Aro, Taye; Thiak, Ang Moon
International journal of engineering and advanced technology,
11/2019, Volume:
8, Issue:
6s3
Journal Article
Open access
Traffic control system is an imperative instrument in traffic management and smart urban development. However, most of the current traffic control systems cannot intercommunicate nor interact with ...each other. Most importantly, none of these systems are proactive and reactive to their immediate traffic environment. Thus, this study explores the design of an agent-based traffic control system where traffic lights can interact and inter-communicate to take prompt traffic control decisions within a traffic area. The study presents an agent-based traffic control system known as ATC. ATC system design was done using Design Science Research Process Model while the system was evaluated using qualitative research methodology. The study argues that there is need for traffic control system to be more reactive and proactive to their immediate traffic environment in order to limit traffic jam in urban areas.
Purpose The purpose of this paper is to analyze the impact of learning in a projectdriven organization and demonstrate analytically how the learning, which takes place during the execution of ...successive projects, and the forgetting that takes place during the dormant time between the project executions, can impact performance and productivity in the future. Designmethodologyapproach A learnforget model was developed using the learning curve concept prevalent in many manufacturing processes. The model assumes that learning occurs while project tasks are being performed and forgetting takes place during dormant times between the successive implementations. The loglinear model was adapted, with both learning and forgetting rates being a function of the doubling or tripling of output. Forgetting is inhibited through the use of knowledge transfer tools such as use of closeout documents or content management platforms. The model is applied to a simulated project environment where a number of projects are executed sequentially, and the results are evaluated using the reduction in total duration and return on investment. Findings Computational results demonstrate that the learning and forgetting rates and level of project closeout effort impact project performance, in the form of reduction in duration, much more significantly compared to the impact of the length of dormant times between the project initiations. Furthermore, even in a slow learning environment, using closeout reports as a knowledge transfer tool, managers can achieve more than a 40 percent reduction in duration after several successive implementations. Research limitationsimplications Although the theoretical development is applicable to a general organizational setting, the empirical testing of the model is done in projectdriven organizations where projects are implemented on an ongoing basis. Practical implications Managers can significantly benefit from the findings of this study. It is shown that the accumulated learning which represents knowledge generated during the implementation of a project, if transferred successfully, improves productivity and enables faster implementation. In a projectdriven organization an almost 80 percent reduction in total duration is achievable with the use of closeout documents. This result promotes the importance of the learning process and managers should enable their team members to learn as much as they can while implementing a task and to document it methodically. Originalityvalue This study constitutes an initial effort to illustrate quantitatively how the level of learning and forgetting impact performance in a projectdriven organization. This study is also original in that it methodically demonstrates the importance of spending time during the phaseout, documenting the project artifacts, that enables knowledge transfer, and thus improves performance.
This study aimed to evaluate the effects of doxorubicin (Dox) on bone microstructure and metabolism in a mouse model of soft tissue sarcoma.
CCRF S-180II cells (2-4×10
cells/0.2 ml) were injected ...subcutaneously into the back of mice. The mice were divided into four groups according to tumor and treatment status and were reared and sacrificed after 2 or 4 weeks. Micro-computed tomography (CT) was performed to calculate the architecture of the femoral bone. The proximal tibia was double stained with tartrate-resistant acid phosphatase (TRACP) and alkaline phosphatase (ALP), and bone morphometry was performed.
Trabecular bone mass was significantly reduced in the Sarcoma and Sarcoma+Dox groups. Cortical bone thickness was reduced in the DOX group, with a stronger effect observed in the Sarcoma+Dox group. In bone morphometry, osteoclast number at the bone surface (Oc.N/BS) was significantly lower in the Dox, Sarcoma, and Sarcoma+Dox groups than in the Control group at 2 weeks. The osteoblast surface at the bone surface (Ob.S/BS) was significantly lower in the Dox and Sarcoma groups than in the Control group at 2 weeks. At 4 weeks, the differences were smaller for both Oc.N/BS and Ob.S/BS.
The use of doxorubicin alone worsened the cortical bone structure; however, the presence of both soft-tissue sarcoma and doxorubicin use worsened both cortical and trabecular bone structures from an early stage.
In the multi-messenger era, coordinating observations between astronomical facilities is mandatory to study transient phenomena (e.g. Gamma-ray bursts) and is achieved by sharing information with the ...scientific community through networks such as the Gamma-ray Coordinates Network. The facilities usually develop real-time scientific analysis pipelines to detect transient events, alert the astrophysical community, and speed up the reaction time of science alerts received from other observatories. We present in this work the RTApipe framework, designed to facilitate the development of real-time scientific analysis pipelines for present and future gamma-ray observatories. This framework provides pipeline architecture and automatisms, allowing the researchers to focus on the scientific aspects and integrate existing science tools developed with different technologies. The pipelines automatically execute all the configured analyses during the data acquisition. This framework can be interfaced with science alerts networks to perform follow-up analysis of transient events shared by other facilities. The analyses are performed in parallel and can be prioritised. The workload is highly scalable on a cluster of machines. The framework provides the required services using containerisation technology for easy deployment. We present the RTA pipelines developed for the AGILE space mission and the prototype of the SAG system for the ground-based future Cherenkov Telescope Array observatory confirming that the RTApipe framework can be used to successfully develop pipelines for the gamma-ray observatories, both space and ground-based.
We have extensively studied the behavior of pronounced subgap structures on the quasiparticle branches of the current-voltage (I-V) characteristics of intrinsic Josephson junctions (IJJs) in (Bi ...sub(1-x)Pb sub(x)) sub( 2)Sr sub(2)CaCu sub(2)O sub(y) (x=0.15, 0.2) single crystals for their applications in THz range. Six subgap structures are successfully observed between 6.3 and 26.2 mV on the first quasiparticle branch at 4.2 K. The intensities of two typical subgap structures at 6.3 and 8.2 mV are found to be approximately proportional to I sub(c) super(2) (critica current) super(2) over a wide range of temperature between 4.2 and ~ 80 K. They are interpreted with regard to the interference of Raman-active optical phonons with ac Josephson currents in IJJs. Under magnetic field up to 2.5 T they have been affected somewhat in the respect to return current, though the vortex flow also has been induced in IJJs. By microwave application of 2-100 GHz they have been strongly affected so that their peak intensities decrease and then each peak splits into two, with increasing microwave power.
The active galactic nucleus PG 1553+113 was observed by the MAGIC telescope in July 2006 during a multiwavelength campaign, in which telescopes in the optical, X-ray, and very high energies ...participated. Although the MAGIC data were affected by strong atmospheric absorption (calima), they were analyzed after applying a correction. In 8.5 h, a signal was detected with a significance of 5.0σ. The integral flux above 150 GeV was $(2.6\pm0.9)\times 10^{-7}~{\rm ph\,s^{-1}\,m^{-2}}$. By fitting the differential energy spectrum with a power law, a spectral index of $-4.1\pm0.3$ was obtained.
The Cherenkov Telescope Array (CTA) Observatory, with dozens of telescopes located in both the Northern and Southern Hemispheres, will be the largest ground-based gamma-ray observatory and will ...provide broad energy coverage from 20 GeV to 300 TeV. The large effective area and field-of-view, coupled with the fast slewing capability and unprecedented sensitivity, make CTA a crucial instrument for the future of ground-based gamma-ray astronomy. To maximise the scientific return, the array will send alerts on transients and variable phenomena (e.g. gamma-ray burst, active galactic nuclei, gamma-ray binaries, serendipitous sources). Rapid and effective communication to the community requires a reliable and automated system to detect and issue candidate science alerts. This automation will be accomplished by the Science Alert Generation (SAG) pipeline, a key system of the CTA Observatory. SAG is part of the Array Control and Data Acquisition (ACADA) working group. The SAG working group develops the pipelines to perform data reconstruction, data quality monitoring, science monitoring and real-time alert issuing during observations to the Transients Handler functionality of ACADA. SAG is the system that performs the first real-time scientific analysis after the data acquisition. The system performs analysis on multiple time scales (from seconds to hours). \abrb{SAG must issue candidate science alerts within} 20 seconds from the data taking and with sensitivity at least half of the CTA nominal sensitivity. These challenging requirements must be fulfilled by managing trigger rates of tens of kHz from the arrays. Dedicated and highly optimised software and hardware architecture must thus be designed and tested. In this work, we present the general architecture of the ACADA-SAG system.
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