9,770 research outputs found

    Organizational change factors for increasing online learning within a southeastern state university system

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    This bounded case study describes the readiness of a Southeastern State University System to support the growth of online learning. Structured as a case study, the view provided of the Southeastern State University System in this moment in time provides a contextually rich view of the phenomenon of change within a university system. The study answers the following questions regarding the change towards online course delivery: Does the Southeastern State University System have a primarily transformational or transactional orientation? What are the key change facilitating factors within the Southeastern State University System? What are the key change restraining factors within the Southeastern State University System? The key change facilitating factors identified as part of the first phase of the study included: motivation to change, job/task requirements and organizational culture supportive of change. The perspectives of the administrators regarding facilitating factors differed, as did views on if the organizational culture was supportive of change. The CIO interviewed described a variation in perspectives regarding online learning based on institutional categories and missions, which was reflected in the interviews. The key change restraining factors were identified during the survey phase of the study as: change related systems, emotional impact of change and change mission and strategy. Financial incentives, both for the institutions and the individuals involved in online or blended activities was identified in the interviews. However, the CIO interviewed outlined a perspective that the funding model for collaborative programs in the university system was flawed. A perceived lack of change mission strategy was common through the interviews, with signs pointing towards improvement within the system, with a new focus on online learning as part of an initiative to have more college graduates within the state. This study provides a snapshot of the state of a university system as it adapts to the changing environment of higher education. The study describes the application of an established organizational change and development model to the study of online learning, which provides future researchers with a framework to investigate online learning at a university system level

    Interaction-induced mode switching in steady-state microlasers

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    We demonstrate that due to strong modal interactions through cross-gain saturation, the onset of a new lasing mode can switch off an existing mode via a negative power slope. In this process of interaction-induced mode switching (IMS) the two involved modes maintain their identities, i.e. they do not change their spatial field patterns or lasing frequencies. For a fixed pump profile, a simple analytic criterion for the occurrence of IMS is given in terms of their self- and cross-interaction coefficients and non-interacting thresholds, which is verified for the example of a two-dimensional microdisk laser. When the spatial pump profile is varied as the pump power is increased, IMS can be induced even when it would not occur with a fixed pump profile, as we show for two coupled laser cavities. Our findings apply to steady-state lasing and are hence different from dynamical mode switching or hopping. IMS may have potential applications in robust and flexible all-optical switching.Comment: 14 pages, 5 figure

    The pheromone-induced nuclear accumulation of the Fus3 MAPK in yeast depends on its phosphorylation state and on Dig1 and Dig2

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    BACKGROUND: Like mammalian MAP kinases, the mating-specific Fus3 MAPK of yeast accumulates in the nuclei of stimulated cells. Because Fus3 does not appear to be subjected to active nucleo-cytoplasmic transport, it is not clear how its activation by mating pheromone effects the observed change in its localization. One possibility is that the activation of Fus3 changes its affinity for nuclear and cytoplasmic tethers. RESULTS: Dig1, Dig2, and Ste12 are nuclear proteins that interact with Fus3. We found that the pheromone-induced nuclear accumulation of a Fus3-GFP reporter is reduced in cells lacking Dig1 or Dig2, whereas Fus3T180AY182A-GFP localization was unaffected by the absence of these proteins. This suggests that Dig1 and Dig2 contribute to the retention of phosphorylated Fus3 in the nucleus. Moreover, overexpression of Ste12 caused the hyper-accumulation of Fus3-GFP (but not Fus3T180AY182A-GFP) in the nuclei of pheromone-treated cells, suggesting that Ste12 also plays a role in the nuclear retention of phosphorylated Fus3, either by directly interacting with it or by transcribing genes whose protein products are Fus3 tethers. We have previously reported that overexpression of the Msg5 phosphatase inhibits the nuclear localization of Fus3. Here we show that this effect depends on the phosphatase activity of Msg5, and provide evidence that both nuclear and cytoplasmic Msg5 can affect the localization of Fus3. CONCLUSION: Our data are consistent with a model in which the pheromone-induced phosphorylation of Fus3 increases its affinity for nuclear tethers, which contributes to its nuclear accumulation and is antagonized by Msg5

    Installation and Performance of Portland Cement Concrete Pavement Joint Sealers

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    Joints are needed in portland cement concrete pavements to control cracking, relieve pavement stresses due to volume change, and to protect immovable structures. However, when the joints are not properly designed, constructed, and maintained, they may become a source of multiple problems. It is the opinion of many pavement management engineers that the most effective way to prevent and/or correct problems with joints is to use a joint sealer material. The purpose of the sealer is to keep surface water and fine, incompressible material from entering the pavement joint. The Kentucky Transportation Center was contracted by the Kentucky Department of Highways to evaluate the installation and short-term performance of four different types of joint sealants used for portland cement concrete pavements. The four cement concrete pavement joint sealers used in the project were: silicone rubber, self-leveling silicone rubber, preformed polychloroprene compression seal, and conventional hot-poured elastic sealant. The silicone sealants were supplied for the project by the DOW Corning Company. The preformed polychloroprene compression seals were supplied by the D. S. Brown Company. The silicone rubber sealant was sticky, difficult to install properly, and subsequently, is displaying evidence of increased wear. The self-leveling silicone rubber sealant was more fluid, less sticky, easier to install, obtained the correct depth in the joint most consistently, and has performed extremely well to date. The preformed polychloroprene compression seals appeared to be easily installed. However, uniformity in depth below the surface of the joint was not achieved and twisting of some seals was observed. A greater amount of incompressible materials are collecting in the pavement joints containing the preformed polychloroprene compression seals. The hot-poured elastic joint sealer was easily installed but installers had difficulties controlling the rate of application. It was concluded that with proper construction techniques, successful applications of silicone rubber joint sealers will result. The silicone sealants provide an effective means of preventing moisture and incompressible fines from entering the pavement joint. Based on this successful initial application and the excellent short-term performance exhibited thus far, it was recommended that self-leveling silicone rubber sealant be used on a number of additional projects so that a more extensive performance data base may be developed by the Department of Highways

    Analysis of Clumps in Molecular Cloud Models: Mass Spectrum, Shapes, Alignment and Rotation

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    Observations reveal concentrations of molecular line emission on the sky, called ``clumps,'' in dense, star-forming molecular clouds. These clumps are believed to be the eventual sites of star formation. We study the three-dimensional analogs of clumps using a set of self-consistent, time-dependent numerical models of molecular clouds. The models follow the decay of initially supersonic turbulence in an isothermal, self-gravitating, magnetized fluid. We find the following. (1) Clumps are intrinsically triaxial. This explains the observed deficit of clumps with a projected axis ratio near unity, and the apparent prolateness of clumps. (2) Simulated clump axes are not strongly aligned with the mean magnetic field within clumps, nor with the large-scale mean fields. This is in agreement with observations. (3) The clump mass spectrum has a high-mass slope that is consistent with the Salpeter value. There is a low-mass break in the slope at \sim 0.5 \msun, although this may depend on model parameters including numerical resolution. (4) The typical specific spin angular momentum of clumps is 4×1022cm2s14 \times 10^{22} {\rm cm^2 s^{-1}}. This is larger than the median specific angular momentum of binary stars. Scaling arguments suggest that higher resolution simulations may soon be able to resolve the scales at which the angular momentum of binary stars is determined.Comment: 14 pages, 13 figures, to appear in 2003 July 20 Ap

    Spin-dynamics of the low-dimensional magnet (CH3)2NH2CuCl3

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    Dimethylammonium copper (II) chloride (also known as DMACuCl3 or MCCL) is a low dimensional S=1/2 quantum spin system proposed to be an alternating ferro-antiferromagnetic chain with similar magnitude ferromagnetic (FM) and antiferromagnetic (AFM) exchange interactions. Subsequently, it was shown that the existing bulk measurements could be adequately modeled by considering DMACuCl3 as independent AFM and FM dimer spin pairs. We present here new inelastic neutron scattering measurements of the spin-excitations in single crystals of DMACuCl3. These results show significant quasi-one-dimensional coupling, however the magnetic excitations do not propagate along the expected direction. We observe a band of excitations with a gap of 0.95 meV and a bandwidth of 0.82 meV.Comment: 3 pages, 2 figures included in text, submitted to proceedings of International Conference on Neutron Scattering, December 200

    A Kerr-microresonator optical clockwork

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    Kerr microresonators generate interesting and useful fundamental states of electromagnetic radiation through nonlinear interactions of continuous-wave (CW) laser light. Using photonic-integration techniques, functional devices with low noise, small size, low-power consumption, scalable fabrication, and heterogeneous combinations of photonics and electronics can be realized. Kerr solitons, which stably circulate in a Kerr microresonator, have emerged as a source of coherent, ultrafast pulse trains and ultra-broadband optical-frequency combs. Using the f-2f technique, Kerr combs support carrier-envelope-offset phase stabilization for optical synthesis and metrology. In this paper, we introduce a Kerr-microresonator optical clockwork based on optical-frequency division (OFD), which is a powerful technique to transfer the fractional-frequency stability of an optical clock to a lower frequency electronic clock signal. The clockwork presented here is based on a silicon-nitride (Si3_3N4_4) microresonator that supports an optical-frequency comb composed of soliton pulses at 1 THz repetition rate. By electro-optic phase modulation of the entire Si3_3N4_4 comb, we arbitrarily generate additional CW modes between the Si3_3N4_4 comb modes; operationally, this reduces the pulse train repetition frequency and can be used to implement OFD to the microwave domain. Our experiments characterize the residual frequency noise of this Kerr-microresonator clockwork to one part in 101710^{17}, which opens the possibility of using Kerr combs with high performance optical clocks. In addition, the photonic integration and 1 THz resolution of the Si3_3N4_4 frequency comb makes it appealing for broadband, low-resolution liquid-phase absorption spectroscopy, which we demonstrate with near infrared measurements of water, lipids, and organic solvents

    Bayesian uncertainty-weighted loss for improved generalisability on polyp segmentation task

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    While several previous studies have devised methods for segmentation of polyps, most of these methods are not rigorously assessed on multi-center datasets. Variability due to appearance of polyps from one center to another, difference in endoscopic instrument grades, and acquisition quality result in methods with good performance on in-distribution test data, and poor performance on out-of-distribution or underrepresented samples. Unfair models have serious implications and pose a critical challenge to clinical applications. We adapt an implicit bias mitigation method which leverages Bayesian epistemic uncertainties during training to encourage the model to focus on underrepresented sample regions. We demonstrate the potential of this approach to improve generalisability without sacrificing state-of-the-art performance on a challenging multi-center polyp segmentation dataset (PolypGen) with different centers and image modalities.Comment: To be presented at the Fairness of AI in Medical Imaging (FAIMI) MICCAI 2023 Workshop and published in volumes of the Springer Lecture Notes Computer Science (LNCS) serie
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