960 research outputs found
Ethical Leadership: Not Everyone Responds Equally
Theoretical frameworks associated with ethical leadership have not fully considered the nature of the leaderâfollower exchange, and, in addition, few studies have considered the impact of follower individual differences in reactions to ethical leadership. Our research extends the customary social exchange perspective of transactional and relational resources by accounting for the ideological resources (i.e., value-oriented principles) that can also imbue the leaderâsubordinate relationship. Second, differences in equity sensitivity are hypothesized to moderate the influence of ethical leadership on employee attachment to the organization. We predicted that the impact of ethical leadership on organizational commitment, job satisfaction, and organizational identification is greater for individuals with a more benevolent orientation. In Study 1 (N = 223), equity sensitivity moderated the influence of ethical leadership on organizational commitment and organizational identification. In Study 2 (N = 244), an interactive effect was found for the outcomes of organizational commitment and job satisfaction. We consider the theoretical implications of how and why ethical leadership influences follower attitudes and beliefs
Community Seismic Network: A Dense Array to Sense Earthquake Strong Motion
The Community Seismic Network (CSN) is currently a 500âelement strongâmotion network located in the Los Angeles area of California (see Fig. 1). The sensors in the network are lowâcost microelectromechanical (MEM) accelerometers that are capable of recording on scale up to accelerations of ±2g. The primary product of the network is a set of measurements of ground shaking in the seconds following a major earthquake. An example of this is shown in Figure 2. The shaking information will be contributed to U.S. Geological Survey products such as ShakeMap (Wald et al., 1999) and ShakeCast (Wald et al., 2006), with the goal of providing first responders a proxy for damage that can guide efforts immediately following the event. The basic premise is the strong groundâmotion shaking varies on a subkilometer scale, which will require a dense network to meaningfully measure the shaking. Evidence for this comes from earthquakes recorded by dense oil company surveys in the Los Angeles area (Clayton et al., 2011)
The Properties and Functions of Glial Cell Types of the Hypothalamic Median Eminence
The median eminence (ME) is part of the neuroendocrine system (NES) that functions as a crucial interface between the hypothalamus and pituitary gland. The ME contains many non-neuronal cell types, including oligodendrocytes, oligodendrocyte precursor cells (OPCs), tanycytes, astrocytes, pericytes, microglia and other immune cells, which may be involved in the regulation of NES function. For example, in mice, ablation of tanycytes (a special class of ependymal glia with stem cell-like functions) results in weight gain, feeding, insulin insensitivity and increased visceral adipose, consistent with the demonstrated ability of these cells to sense and transport both glucose and leptin, and to differentiate into neurons that control feeding and metabolism in the hypothalamus. To give a further example, OPCs in the ME of mice have been shown to rapidly respond to dietary signals, in turn controlling composition of the extracellular matrix in the ME, derived from oligodendrocyte-lineage cells, which may contribute to the previously described role of these cells in actively maintaining leptin-receptor-expressing dendrites in the ME. In this review, we explore and discuss recent advances such as these, that have developed our understanding of how the various cell types of the ME contribute to its function in the NES as the interface between the hypothalamus and pituitary gland. We also highlight avenues of future research which promise to uncover additional functions of the ME and the glia, stem and progenitor cells it contains
Community Seismic Network
The article describes the design of the Community Seismic Network, which is a dense open seismic network based on low cost sensors. The inputs are from sensors hosted by volunteers from the community by direct connection to their personal computers, or through sensors built into mobile devices. The server is cloud-based for robustness and to dynamically handle the load of impulsive earthquake events. The main product of the network is a map of peak acceleration, delivered within seconds of the ground shaking. The lateral variations in the level of shaking will be valuable to first responders, and the waveform information from a dense network will allow detailed mapping of the rupture process. Sensors in buildings may be useful for monitoring the state-of-health of the structure after major shaking
Individual-specific changes in the human gut microbiota after challenge with enterotoxigenic Escherichia coli and subsequent ciprofloxacin treatment
Acknowledgements The authors wish to thank Mark Stares, Richard Rance, and other members of the Wellcome Trust Sanger Instituteâs 454 sequencing team for generating the 16S rRNA gene data. Lili Fox VĂ©lez provided editorial support. Funding IA, JNP, and MP were partly supported by the NIH, grants R01-AI-100947 to MP, and R21-GM-107683 to Matthias Chung, subcontract to MP. JNP was partly supported by an NSF graduate fellowship number DGE750616. IA, JNP, BRL, OCS and MP were supported in part by the Bill and Melinda Gates Foundation, award number 42917 to OCS. JP and AWW received core funding support from The Wellcome Trust (grant number 098051). AWW, and the Rowett Institute of Nutrition and Health, University of Aberdeen, receive core funding support from the Scottish Government Rural and Environmental Science and Analysis Service (RESAS).Peer reviewedPublisher PD
2019 Ridgecrest Earthquake Reveals Areas of Los Angeles That Amplify Shaking of High-Rises
The populace of Los Angeles, California, was startled by shaking from the M 7.1 earthquake that struck the city of Ridgecrest located 200 km to the north on 6 July 2019. Although the earthquake did not cause damage in Los Angeles, the experience in highârise buildings was frightening in contrast to the shaking felt in short buildings. Observations from 560 groundâlevel accelerometers reveal large variations in shaking in the Los Angeles basin that occurred for more than 2 min. The observations come from the spatially dense Community Seismic Network (CSN), combined with the sparser Southern California Seismic Network and California Strong Motion Instrumentation Program networks. Site amplification factors for periods of 1, 3, 6, and 8 s are computed as the ratio of each stationâs response spectral values combined for the two horizontal directions, relative to the average of three bedrock sites. Spatially coherent behavior in site amplification emerges for periods â„3ââsâ , and the maximum calculated site amplifications are the largest, by factors of 7, 10, and 8, respectively, for 3, 6, and 8 s periods. The dense CSN observations show that the longâperiod amplification is clearly, but only partially, correlated with the depth to basement. Sites with the largest amplifications for the long periods (â â„3ââsâ ) are not close to the deepest portion of the basin. At 6 and 8 s periods, the maximum amplifications occur in the western part of the Los Angeles basin and in the southâcentral San Fernando Valley sedimentary basin. The observations suggest that the excitation of a hypothetical highârise located in an area characterized by the largest site amplifications could be four times larger than in a downtown Los Angeles location
2D/3D Visual Tracker for Rover Mast
A visual-tracker computer program controls an articulated mast on a Mars rover to keep a designated feature (a target) in view while the rover drives toward the target, avoiding obstacles. Several prior visual-tracker programs have been tested on rover platforms; most require very small and well-estimated motion between consecutive image frames a requirement that is not realistic for a rover on rough terrain. The present visual-tracker program is designed to handle large image motions that lead to significant changes in feature geometry and photometry between frames. When a point is selected in one of the images acquired from stereoscopic cameras on the mast, a stereo triangulation algorithm computes a three-dimensional (3D) location for the target. As the rover moves, its body-mounted cameras feed images to a visual-odometry algorithm, which tracks two-dimensional (2D) corner features and computes their old and new 3D locations. The algorithm rejects points, the 3D motions of which are inconsistent with a rigid-world constraint, and then computes the apparent change in the rover pose (i.e., translation and rotation). The mast pan and tilt angles needed to keep the target centered in the field-of-view of the cameras (thereby minimizing the area over which the 2D-tracking algorithm must operate) are computed from the estimated change in the rover pose, the 3D position of the target feature, and a model of kinematics of the mast. If the motion between the consecutive frames is still large (i.e., 3D tracking was unsuccessful), an adaptive view-based matching technique is applied to the new image. This technique uses correlation-based template matching, in which a feature template is scaled by the ratio between the depth in the original template and the depth of pixels in the new image. This is repeated over the entire search window and the best correlation results indicate the appropriate match. The program could be a core for building application programs for systems that require coordination of vision and robotic motion
Structure of the subduction system in southern Peru from seismic array data
The subduction zone in southern Peru is imaged using converted phases from teleseismic P, PP, and PKP waves and Pwave tomography using local and teleseismic events with a linear array of 50 broadband seismic stations spanning 300 km from the coast to near Lake Titicaca. The slab dips at 30° and can be observed to a depth of over 200 km. The Moho is seen as a continuous interface along the profile, and the crustal thickness in the back-arc region (the Altiplano) is 75 km thick, which is sufficient to isostatically support the Andes, as evidenced by the gravity. The shallow crust has zones of negative impedance at a depth of 20 km, which is likely the result of volcanism. At the midcrustal level of 40 km, there is a continuous structure with a positive impedance contrast, which we interpret as the western extent of the Brazilian Craton as it underthrusts to the west. V_p/V_s ratios estimated from receiver function stacks show average values for this region with a few areas of elevated V_p/V_s near the volcanic arc and at a few points in the Altiplano. The results support a model of crustal thickening in which the margin crust is underthrust by the Brazilian Shield
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