Perceptions of Leadership Characteristics of Principals who Influence Positive School Culture in a Midwest Adventist Union : a Qualitative Study

Problem. Principals struggle to sustain a positive culture in their schools. Many studies have identified that principals play a key role in influencing the school culture. However, no known study has examined leadership characteristics of Adventist principals and their influence on positive school culture in Adventist schools. Purpose. The purpose of this study was to understand and describe leadership characteristics of principals, who foster a positive culture in Adventist schools in a Midwest Seventh-day Adventist Union. Method. This qualitative multiple-case study design was utilized to explore and describe the lived experiences of principals and key stakeholders, school board chairs, and teachers about their perceptions of leadership characteristics of Adventist principals who influence positive school culture. The criterion used to identify the purposive sample was the inter-rater reliability process, in which education leaders from Midwest Adventist Union and four of the local conferences identified schools that have a positive school culture based on an agreed standard, and gave permission to conduct the study. Data collection occurred through in-person interviews with 12 purposively selected participants, informal observation, and field notes obtained at the four school sites. Interviews were transcribed verbatim, coded, and make categorized in an ongoing iterative process to establish validity, draw meaning, and make conclusions about the issue. Findings. Principals in this study influenced a positive school culture by embracing their multifaceted role as chief culture leaders in their schools. However, they also acknowledged that the task of maintaining a positive school culture required total dependence on God, and a pervasive attitude of continuous improvement, which could not be achieved without the co-leadership of teachers and collegial collaboration with all stakeholders, staff members and school board, primarily the board chair. The principals described being intentional to treat staff members as trained professionals, and to include them first in planning for improvement of the school. Key stakeholders, school board chairs, and teachers viewed their principals’ leadership as paramount in creating and maintaining a positive school culture, as they looked to them to set a focused direction and high standards of conduct for the school environment. A majority of the stakeholders believed school culture had a greater influence on behavior and achievement among students and teachers. The study revealed shared vision, diversity celebrated, and a pervasive attitude of continuous growth and improvement as common elements that defined positive school culture. In addition, commitment to behavior and core values, interpersonal communication, and the importance of principal relationships emerged as best leadership qualities for cultivating and maintaining positive school culture in Adventist K-12 schools in a Midwest Seventh-day Adventist Union

Physical layer transmitter and routing optimization to maximize the traffic throughput of a nonlinear optical mesh network

This paper investigates the physical layer optimization as a means of improving the utilization of limited network resources. A transparent optical network operating in the nonlinear transmission regime using coherent optical technology is considered. A physical layer model is described that allows the transmission signal quality to be included in the optimization process. Initially a fixed power, route-adapted modulation format approach is taken using integer linear programming to solve the static route allocation problem. It is shown that for the 14-node, 21-link NSF mesh network adaptation of the modulation formats leads to increases in data throughput of 17%. Optimization of the individual transmitter launch powers and spectral channel allocation results in a SNR margin of 2.3 dB, which is used to further increase the overall network traffic throughput exceeding the fixed PM-QPSK modulation format by as much as 50%. Compared to other work this paper highlights that increased gains in network throughput can be achieved if nonlinear interference is included in the routing and spectral assignment algorithm and individual transmitter spectral assignment and launch power is optimized to minimize nonlinear interference

Does the UTTO model of technology transfer fit public sector healthcare services?

Public sector healthcare services are both large users and innovators of health technologies. In the UK's National Health Service (NHS) initiatives have been developed to manage the process of technological innovation more effectively. This has two main aims, to maximize potential commercial returns from innovations developed within the NHS; and to improve levels of patient care through appropriate diffusion of innovations. The initiatives have been devised using approaches and processes already used in other public sector organizations, in particular, universities. Central to the approach taken by many universities is the setting up of a university technology transfer office (UTTO) to provide innovation management services. This paper assesses the extent to which the UTTO-based approach to technology transfer matches the needs of the NHS. Several significant factors are identified that suggest that the two sectors merit different approaches to innovation management. An agenda for further research into health service innovation management processes is suggested that emphasises issues including: the relative roles of formal and informal innovation processes; contingent variables affecting design of innovation processes; limitations of technology-push approaches to managing practice-based innovation; and cultural fit of innovation management models

Overview of high-speed TDM-PON beyond 50 Gbps per wavelength using digital signal processing [Invited Tutorial]

The recent evolution of passive optical network standards and related research activities for physical layer solutions that achieve bit rates well above 10 Gbps per wavelength (lambda) is discussed. We show that the advancement toward 50, 100, and 200 Gbps/lambda will certainly require a strong introduction of advanced digital signal processing (DSP) technologies for linear, and maybe nonlinear, equalization and for forward error correction. We start by reviewing in detail the current standardization activities in the International Telecommunication Union and the Institute of Electrical and Electronics Engineers, and then we present a comparison of the DSP approaches for traditional direct detection solutions and for future coherent detection approaches. (c) 2022 Optica Publishing Grou

The benefit of split nonlinearity compensation for single-channel optical fiber communications

In this Letter we analyze the benefit of digital compensation of fiber nonlinearity, where the digital signal processing is divided between the transmitter and receiver. The application of the Gaussian noise model indicates that, where there are two or more spans, it is always beneficial to split the nonlinearity compensation. The theory is verified via numerical simulations, investigating transmission of single channel 50 GBd polarization division multiplexed 256-ary quadrature amplitude modulation over 100 km standard single mode fiber spans, using lumped amplification. For this case, the additional increase in mutual information achieved over transmitter- or receiver-side nonlinearity compensation is approximately 1 bit for distances greater than 2000 km. Further, it is shown, theoretically, that the SNR gain for long distances and high bandwidth transmission is 1.5 dB versus transmitter- or receiver-based nonlinearity compensation

Network equipment and their procurement strategy for high capacity elastic optical networks

© 2016 Optical Society of America. In elastic optical networks, the success of providing high network capacity depends on the optical signal-to-noise ratio (OSNR) values of network lightpaths. As each lightpaths OSNR value defines the modulation format and capacity it can support, having high OSNRlightpaths is always beneficial. Hence, with a given set of modulation formats, service providers need to optimize their optical infrastructure, including in-line amplifiers and reconfigurable optical add-drop multiplexers (ROADMs), given the size and topology of their core networks. This also will have a direct impact on vendors who need strong insight into the requirements of service providers and their networks in terms of equipment and new technology. Therefore, in this paper a comprehensive model based on the local optimization which leads to a global network optimization (LOGON) strategy of the Gaussian noise (GN) model has been proposed, which helps in estimating the lightpath OSNR and clearly quantifies the noise contributions from in-line amplifiers and post-amplification at the ROADMs. The model introduces closed-form expressions to calculate nonlinear impairment (NLI) contributions for various span lengths while using either erbium-doped fiber amplifiers (EDFAs) or H-Raman amplifiers, which helps in optimizing the signal launch power to achieve maximum link OSNR. In addition to this, an offline strategy has been proposed that can help service providers to optimize their procurement of network equipment upfront and give insight into how much of the capacity bottleneck is alleviated in their networks if they do this. To demonstrate all of the above, the UK, Pan-European, and US Core networks have been considered, which illustrate differences in link lengths and reduced node density. It is seen that improving the OSNR conditions at the ROADM increases the network capacity when noise from in-line amplifiers is significantly reduced. Among the three networks, we found that the UK network responded the most to improved OSNR conditions at the ROADM nodes due to small link lengths and less line noise. Among the amplifiers, we found that improving ROADMs while having H-Raman in the links resulted in a maximum capacity increase. For the UK network at FG=12.5 GHz, the capacity increases by 6650 Gbps, while for the larger Pan-European and US networks, the capacity increase reduces to 4550 and 1600 Gbps due to increased link lengths and line noise. Further, following the offline strategy, we are able to accommodate 1737, 1481, and 615 100G demands using H-Raman for the UK, Pan-EU, and US networks at FG=12.5 GHz until 10%blocking is reached. Thereby, H-Raman provides 7.5%, 35.8%, and 94.9%extra capacity, respectively, for the UK, Pan-EU, and US. Finally, using H-Raman, all lightpaths in the UK network operate at PM-64QAM with maximum capacity at the end of the procedure.INSIGHT - EP/L026155/

Why compensating fibre nonlinearity will never meet capacity demands

Current research efforts are focussed on overcoming the apparent limits of communication in single mode optical fibre resulting from distortion due to fibre nonlinearity. It has been experimentally demonstrated that this Kerr nonlinearity limit is not a fundamental limit; thus it is pertinent to review where the fundamental limits of optical communications lie, and direct future research on this basis. This paper details recently presented results. The work herein briefly reviews the intrinsic limits of optical communication over standard single mode optical fibre (SMF), and shows that the empirical limits of silica fibre power handling and transceiver design both introduce a practical upper bound to the capacity of communication using SMF, on the order of 1 Pbit/s. Transmission rates exceeding 1 Pbit/s are shown to be possible, however, with currently available optical fibres, attempts to transmit beyond this rate by simply increasing optical power will lead to an asymptotically zero fractional increase in capacity

Routing, modulation, spectrum and launch power assignment to maximize the traffic throughput of a nonlinear optical mesh network

We investigate the optimization of routing, modulation format adaptation, spectral and launch power assignment as a means of improving the utilization of limited network resources and increasing the network throughput. We consider a transparent optical network operating in the nonlinear transmission regime and using the latest software adapted coherent optical techniques. We separate the problem into one of routing, modulation adaption and channel assignment, followed by channel spectral assignment, and launch power allocation. It is shown, for three test networks, that the launch power allocation and channel spectral assignment can improve the transmission SNR margin over the fixed modulation, fixed power, fully loaded link worst case by approximately 3–4 dB. This increase in SNR margin can be utilized through modulation format adaption to increase the overall network throughput. This paper highlights that increased gains in network throughput can be achieved in nonlinear impaired networks when individual transmitter spectral assignment and launch power are optimized to minimize the nonlinear interference