The Rwenzori Mountains, a Paleoproterzoic crustal shear belt crossing the Albertine rift system

This contribution discusses the development of the Paleoproterozoic Buganda-Toro belt in the Rwenzori mountains and its influence on the western part of the East African Rift System in Uganda. The Buganda-Toro belt is composed of several thick-skinned nappes consisting of Archaean Gneisses and Palaeoproterozoic cover units that are thrusted northwards. The high Rwenzori mountains are located in the frontal unit of this belt with retrograde greenschist facies gneisses towards the north, which are unconformably overlain by metasediments and amphibolites. Towards the south the metasediments are overthrust by the next migmatitic gneiss unit that belongs to a crustal scale nappe. The southwards dipping metasedimentary and volcanic sequence in the high Rwenzori mountains shows an inverse metamorphic grade with greenschist facies conditions in the north and amphibolite facies conditions in the south. Early D1 deformation structures are overgrown by cordierite, which in turn grows into D2 deformation, representing the major northwards directed thrusting event. We argue that the inverse metamorphic gradient develops because higher grade rocks are exhumed in the footwall of a crustal scale nappe whereas the exhumation decreases towards the north away from the nappe leading to a decrease in metamorphic grade. The D2 deformation event is followed by a D3 E-W compression, a D4 with the development of steep shear zones with a NNE-SSW and SSE-NNW trend including the large Nyamwamba shear followed by a local D5 retrograde event and D6 brittle inverse faulting. The Paleoproterozoic Buganda-Toro belt is relatively stiff and crosses the NNE-SSW running rift system exactly at the node where the highest peaks of the Rwenzori mountains are situated and where the lake George rift terminates towards the north. Orientation of brittle and ductile fabrics show some similarities indicating that the cross-cutting Buganda-Toro belt influenced rift propagation and brittle fault development within the Rwenzori mountain and that this stiff belt may form part of the reason why the Rwenzori mountains are relatively high within the rift. Keywords: East African Rift, Basement, Buganda Toro, Inverse Metamorphic Gradient, Microtectonics, Rwenzori mountain

Lessons Learned: Nurses’ Experiences with Errors in Nursing

Background Health care organizations seek to maximize the reporting of medical errors to improve patient safety. Purpose This study explored licensed nurses' decision-making with regard to reporting medical errors. Methods Grounded theory methods guided the study. Thirty nurses from adult intensive care units were interviewed, and qualitative analysis was used to develop a theoretical framework based on their narratives. Discussion The theoretical model was titled “Learning Lessons from the Error.” The concept of learning lessons was central to the theoretical model. The model included five stages: Being Off-Kilter, Living the Error, Reporting or Telling About the Error, Living the Aftermath, and Lurking in Your Mind. Conclusion This study illuminates the unique experiences of licensed nurses who have made medical errors. The findings can inform initiatives to improve error reporting and to support nurses who have made errors

Revitalizing Snow Brand Milk

This case study explores the food poisoning crisis at Snow Brand Milk, one of Japan\u27s largest dairy companies. It examines in particular how the firm successfully revitalized itself and saved the brand

Fracturing and Porosity Channeling in Fluid Overpressure Zones in the Shallow Earth’s Crust

At the time of energy transition, it is important to be able to predict the effects of fluid overpressures in different geological scenarios as these can lead to the development of hydrofractures and dilating high-porosity zones. In order to develop an understanding of the complexity of the resulting effective stress fields, fracture and failure patterns, and potential fluid drainage, we study the process with a dynamic hydromechanical numerical model. The model simulates the evolution of fluid pressure buildup, fracturing, and the dynamic interaction between solid and fluid. Three different scenarios are explored: fluid pressure buildup in a sedimentary basin, in a vertical zone, and in a horizontal layer that may be partly offset by a fault. Our results show that the geometry of the area where fluid pressure is successively increased has a first-order control on the developing pattern of porosity changes, on fracturing, and on the absolute fluid pressures that sustained without failure. If the fluid overpressure develops in the whole model, the effective differential and mean stress approach zero and the vertical and horizontal effective principal stresses flip in orientation. The resulting fractures develop under high lithostatic fluid overpressure and are aligned semihorizontally, and consequently, a hydraulic breccia forms. If the area of high fluid pressure buildup is confined in a vertical zone, the effective mean stress decreases while the differential stress remains almost constant and failure takes place in extensional and shear modes at a much lower fluid overpressure. A horizontal fluid pressurized layer that is offset shows a complex system of effective stress evolution with the layer fracturing initially at the location of the offset followed by hydraulic breccia development within the layer. All simulations show a phase transition in the porosity where an initially random porosity reduces its symmetry and forms a static porosity wave with an internal dilating zone and the presence of dynamic porosity channels within this zone. Our results show that patterns of fractures, hence fluid release, that form due to high fluid overpressures can only be successfully predicted if the geometry of the geological system is known, including the fluid overpressure source and the position of seals and faults that offset source layers and seals

Climate and Soil Moisture Dynamics Inform Potential Climate Change Impacts on Available Moisture and Juvenile Tree Survival in Semiarid Forests

Trees in semiarid forests and woodlands of the western United States need soil moisture to transpire and function. Juvenile trees are especially vulnerable during periods of low soil moisture as their rooting zones are smaller and shallower than those of adult trees. This thesis focuses on two soil moisture-driven aspects of semiarid forests that may be modified by climate change: seasonal soil moisture patterns and juvenile tree survival. In chapter 1, I investigated the influence of precipitation on soil moisture across seasons, elevations, soil layers, and periods of low and high precipitation. I developed time-varying definitions of winter (snow accumulation), spring (moisture recharge), and summer (moisture deficit) that could be applied broadly to sites across the southwestern United States. Higher elevation sites (\u3e 2800 m) displayed similar patterns of greater winter precipitation, longer springs, and shorter summers compared to lower elevation sites (\u3c 2500 m). Across season influence of soil moisture (e.g. an earlier season’s similarity to subsequent seasons) was high when the first season experienced above- or below-average precipitation and the next season experienced average precipitation, highlighting an important connection through time initiated by wet or dry conditions. Soil moisture in the summer season of moisture deficit relied entirely on precipitation events for recharge. In chapter 2, I investigated the effect of a single season of moisture deficit on ponderosa pine juvenile survival and functioning. Juvenile ponderosa pine experimentally treated with small rainfall events for a moderate dry period of 45 days experienced widespread loss of function and mortality regardless of microclimate and total rainfall. A single season of moisture deficit has the potential to severely limit regeneration success in semiarid forests. My research identifies broad similarities in precipitation-soil moisture relationships across the southwestern United States, the extent to which average moisture conditions are a barrier to semiarid forest regeneration, and how these relationships between precipitation, soil moisture, and juvenile tree survival may be altered in a changing climate. Overall, my thesis highlights the climate change-influenced conditions that may negatively impact semiarid forest persistence in the future

Successive interacting coronal mass ejections: How to create a perfect storm?

Coronal mass ejections (CMEs) are the largest type of eruptions on the Sun and the main driver of severe space weather at the Earth. In this study, we implement a force-free spheromak CME description within 3D magnetohydrodynamic simulations to parametrically evaluate successive interacting CMEs within a representative heliosphere. We explore CME–CME interactions for a range of orientations, launch time variations, and CME handedness and quantify their geo-effectiveness via the primary solar wind variables and empirical measures of the disturbance storm time index and subsolar magnetopause standoff distance. We show how the interaction of two moderate CMEs between the Sun and the Earth can translate into extreme conditions at the Earth and how CME–CME interactions at different radial distances can maximize different solar wind variables that induce different geophysical impacts. In particular, we demonstrate how the orientation and handedness of a given CME can have a significant impact on the conservation and loss of magnetic flux, and consequently Bz, due to magnetic reconnection with the interplanetary magnetic field. This study thus implicates the identification of CME chirality in the solar corona as an early diagnostic for forecasting geomagnetic storms involving multiple CMEs

Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey

We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg^2 and span distances ranging from 3-30 kpc from the Galactic Center. Object selection is based on phased, photometric data with 28-50 epochs. We use this large sample to explore the bulk properties of the stellar halo, including the spatial distribution. The period-amplitude distribution of this sample shows that the majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a significant fraction (26 %) which have longer periods and appear to be Oosterhoff type II. We find that the radial distributions of these two populations have significantly different profiles (rho_{OoI} ~ R^(-2.26 +- 0.07) and rho_{OoII} ~ R^(-2.88 +- 0.11). This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models.Comment: 18 pages, 28 figures, apjemulated, minor corrections and clarifications. Accepted to ApJ on Jan 21, 200

Innovative interstellar explorer

An interstellar "precursor" mission has been under discussion in the scientific community for at least 30 years. Fundamental scientific questions about the interaction of the Sun with the interstellar medium can only be answered with in situ measurements that such a mission can provide. The Innovative Interstellar Explorer (IIE) and its use of Radioisotope Electric Propulsion (REP) is being studied under a NASA "Vision Mission" grant. Speed is provided by a combination of a high-energy launch, using current launch vehicle technology, a Jupiter gravity assist, and long-term, low-thrust, continuous acceleration provided by an ion thruster running off electricity provided by advanced radioisotope electric generators. A payload of ten instruments with an aggregate mass of ~35 kg and requiring ~30 W has been carefully chosen to address the compelling science questions. The nominal 20-day launch window opens on 22 October 2014 followed by a Jupiter gravity assist on 5 February 2016. The REP system accelerates the spacecraft to a "burnout" speed of 7.8 AU per year at 104 AU on 13 October 2032 (Voyager 1's current speed is ~3.6 AU/yr). The spacecraft will return at least 500 bits per second from at least 200 AU ~30 years after launch. Additional (backup) launch opportunities occur every 13 months to early 2018. In addition to addressing basic heliospheric science, the mission will ensure continued information on the far-heliospheric galactic cosmic ray population after the Voyagers have fallen silent and as the era of human Mars exploration begins

Activation of stylolites as conduits for overpressured fluid flow in dolomitized platform carbonates

This research was developed with funding provided by the Spanish Government I+D+I Research Projects CGL2015-69805-P and CGL2015-66335-C2-1-R, and the Generalitat de Catalunya (2014SGR251). The research also benefited from a grant of the Geological Society of London (Elspeth Matthews Fund 2015) to EGR. The authors would like to thank M. Aston and O. P. Wennberg for the editorial work, and F. Laponi and an anonymous reviewer for their critical and constructive comments.Peer reviewedPostprin