6,647 research outputs found
Expanding the application of the Eu-oxybarometer to the lherzolitic shergottites and nakhlites: Implications for the oxidation state heterogeneity of the Martian interior
Experimentally rehomogenized melt inclusions from the nakhlite Miller Range 03346 (MIL 03346) and the lherzolitic shergottite Allan Hills 77005 (ALH 77005) have been analyzed for their rare earth element (REE) concentrations in order to characterize the early melt compositions of these Martian meteorites and to calculate the oxygen fugacity conditions they crystallized under. D(Eu/Sm)pyroxene/melt values were measured at 0.77 and 1.05 for ALH 77005 and MIL 03346,
respectively. These melts and their associated whole rock compositions have similar REE patterns, suggesting that whole rock REE values are representative of those of the early melts and can be used as input into the pyroxene Eu-oxybarometer for the nakhlites and lherzolitic shergottites. Crystallization fO_2 values of IW + 1.1 (ALH 77005) and IW + 3.2 (MIL 03346) were calculated. Whole rock data from other nakhlites and lherzolitic shergottites was input into the Eu-oxybarometer to determine their crystallization fO_2 values. The lherzolitic shergottites and nakhlites have fO_2 values that range from IW + 0.4 to 1.6 and from IW + 1.1 to 3.2, respectively. These values are consistent
with some previously determined fO_2 estimates and expand the known range of fO_2 values of the Martian interior to four orders of magnitude. The origins of this range are not well constrained. Possible mechanisms for producing this spread in fO_2 values include mineral/melt fractionation, assimilation, shock effects, and magma ocean crystallization processes. Mineral/melt partitioning can result in changes in fO_2 from the start to the finish of crystallization of 2 orders of magnitude. In addition, crystallization of a Martian magma ocean with reasonable initial water content results in oxidized, water-rich, late-stage cumulates. Sampling of these oxidized cumulates or interactions between reduced melts and the oxidized material can potentially account for the range of fO_2 values observed in the Martian meteorites
Quantifying temporal and spatial variations in sediment, nitrogen and phosphorus transport in stream inflows to a large eutrophic lake
High-frequency sampling of two major stream inflows to a large eutrophic lake (Lake Rotorua, New Zealand) was conducted to measure inputs of total suspended sediment (TSS), and fractions of nitrogen and phosphorus (P). A total of 17 rain events were sampled, including three during which both streams were simultaneously monitored to quantify how concentration–discharge (Q) relationships varied between catchments during similar hydrological conditions. Dissolved inorganic nitrogen (DIN) concentrations declined slightly during events, reflecting dilution of groundwater inputs by rainfall, whereas dissolved inorganic P (PO₄–P) concentrations were variable and unrelated to Q, suggesting dynamic sorptive behaviour. Event loads of total nitrogen (TN) were predominantly DIN, which is available for immediate uptake by primary producers, whereas total phosphorus (TP) loads predominantly comprised particulate P (less labile). Positive correlations between Q and concentrations of TP (and to a lesser extent TN) reflected increased particulate nutrient concentrations at high flows. Consequently, load estimates based on hourly Q during storm events and concentrations of routine monthly samples (mostly base flow) under-estimated TN and TP loads by an average of 19% and 40% respectively. Hysteresis with Q was commonly observed and inclusion of hydrological variables that reflect Q history in regression models improved predictions of TN and TP concentrations. Lorenz curves describing the proportions of cumulative load versus cumulative time quantified temporal inequality in loading. In the two study streams, 50% of estimated two-year loads of TN, TP and TSS were transported in 202–207, 76–126 and 1–8 days respectively. This study quantifies how hydrological and landscape factors can interact to influence pollutant flux at the catchment scale and highlights the importance of including storm transfers in lake loading estimates
Industrial Warehouse Rent Determinants in the Dallas/Fort Worth Area
This paper presents the first empirical analysis of the determinants of pooled variation in industrial warehouse rents. It examines industrial warehouse rents using data for seventeen quarterly periods in the Dallas/Fort Worth metroplex. M/PF Research Inc. provided the data. A random effects model is used to estimate the relationship between market rents for industrial properties and various independent variables. Rent per square foot is positively related to the number of grade high doors, and the annual change in net employment. Rent per square foot is negatively effected by ceiling height, percentage of office space, building age, and the presence of a sprinkler system. The results indicate that rents are significantly impacted by physical characteristics, location, and general market conditions. Additionally, there is evidence to suggest that the relationship between physical characteristics and rents is nonlinear.
Doppler cooling of gallium atoms: 2. Simulation in complex multilevel systems
This paper derives a general procedure for the numerical solution of the
Lindblad equations that govern the coherences arising from multicoloured light
interacting with a multilevel system. A systematic approach to finding the
conservative and dissipative terms is derived and applied to the laser cooling
of gallium. An improved numerical method is developed to solve the
time-dependent master equation and results are presented for transient cooling
processes. The method is significantly more robust, efficient and accurate than
the standard method and can be applied to a broad range of atomic and molecular
systems. Radiation pressure forces and the formation of dynamic dark-states are
studied in the gallium isotope 66Ga.Comment: 15 pages, 8 figure
The Patchwork text assessment - an integral component of constructive alignment curriculum methodology to support healthcare leadership development
Background: A responsive and innovative postgraduate programme curriculum that produces an effective and competent multi professional healthcare leader whom can lead within the United Kingdom (UK) and international healthcare context offers a promising approach to contributing towards the challenging global healthcare agenda.
Aims: The aim of the study is to evaluate the impact of utilising constructive alignment curricular methodology incorporating the Patchwork Text Assessment on the healthcare leadership development of UK and international postgraduate students.
Design: Case study design, incorporating Kirkpatrick's Five Levels of Evaluation Model.
Settings and Participants: 12 post graduate students (multi-professional, UK and international) studying on a healthcare leadership and management programme at one UK University in the North West of England.
Methods: Retrieval of the critical commentary produced and submitted by students as part of the Patchwork Text Assessment process.
Data Analysis: Thematic content analysis approach.
Results: Four key themes emerged demonstrating how the success of constructive alignment and the Patchwork Text Assessment in promoting deep learning for UK and international postgraduate healthcare leadership students is underpinned by principles of good practice and these include:
a) Curriculum planners incorporating work based learning activities into the generated learning activities
b) Curriculum planners creating the best learning environment so the student can achieve the learning activities
c) Providing the learning activities that reflect the real world of healthcare leadership
d) Providing students with opportunities to contextualise theory and practice through relevant patchwork activity and learning activities
e) Equipping students with the transferable postgraduate skills (through learning activities and patch working) to embark on a journey of lifelong learning and continuous professional development
f) Targeting the postgraduate programme /module intended learning outcomes and assessment patches against contemporary leadership qualities frameworks
g) Providing students with opportunities to reflect in multi- professional groups that remain constant in terms of facilitator and supervisor
h) Creating the learning opportunities for students to apply their learning to their own healthcare organisatio
Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year
Assessments of Antarctic temperature change have emphasized the contrast between strong warming of the Antarctic Peninsula and slight cooling of the Antarctic continental interior in recent decades. This pattern of temperature change has been attributed to the increased strength of the circumpolar westerlies, largely in response to changes in stratospheric ozone. This picture, however, is substantially incomplete owing to the sparseness and short duration of the observations. Here we show that significant warming extends well beyond the Antarctic Peninsula to cover most of West Antarctica, an area of warming much larger than previously reported. West Antarctic warming exceeds 0.1 °C per decade over the past 50 years, and is strongest in winter and spring. Although this is partly offset by autumn cooling in East Antarctica, the continent-wide average near-surface temperature trend is positive. Simulations using a general circulation model reproduce the essential features of the spatial pattern and the long-term trend, and we suggest that neither can be attributed directly to increases in the strength of the westerlies. Instead, regional changes in atmospheric circulation and associated changes in sea surface temperature and sea ice are required to explain the enhanced warming in West Antarctica
ASSESSING THE IMPACT OF CHILDHOOD SOCIO-ECONOMIC CONDITIONS ON CHILD MENTAL HEALTH: FINDINGS FROM THE WIRRAL CHILD HEALTH AND DEVELOPMENT STUDY
Combined Diffusion-Relaxometry MRI to Identify Dysfunction in the Human Placenta
Purpose: A combined diffusion-relaxometry MR acquisition and analysis
pipeline for in-vivo human placenta, which allows for exploration of coupling
between T2* and apparent diffusion coefficient (ADC) measurements in a sub 10
minute scan time.
Methods: We present a novel acquisition combining a diffusion prepared
spin-echo with subsequent gradient echoes. The placentas of 17 pregnant women
were scanned in-vivo, including both healthy controls and participants with
various pregnancy complications. We estimate the joint T2*-ADC spectra using an
inverse Laplace transform.
Results: T2*-ADC spectra demonstrate clear quantitative separation between
normal and dysfunctional placentas.
Conclusions: Combined T2*-diffusivity MRI is promising for assessing fetal
and maternal health during pregnancy. The T2*-ADC spectrum potentially provides
additional information on tissue microstructure, compared to measuring these
two contrasts separately. The presented method is immediately applicable to the
study of other organs
The Wealth Effects of Real Estate Spin-Offs
This study examines the wealth effects surrounding the separation of real estate operations via spin-off. Parent firms of spin-offs in this sample experienced a significant abnormal two-day return of 3.195% for days - 1 and 0 of the announcement data in the Wall Street Journal. Tracking the performance of the spun off firms and the parent firms that survived for twenty-four months after the spin-off showed that neither the portfolio of subsidiaries nor the portfolio of parent firms earned returns significantly different from the market portfolio.
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