16,429 research outputs found
Constraining Managers without Owners: Governance of the Not-for-Profit Enterprise
In the absence of owners, how effective are the constraints imposed by the state in promoting effective firm governance? This paper develops state-level indices of the legal and reporting rules facing not-for-profits and examines the effects of these rules on not-for-profit behavior. Stronger non-distribution constraints are associated with greater charitable expenditures and foundation payouts while more stringent reporting requirements are associated with lower insider compensation. The paper also examines how governance influences an alternative metric of not-for-profit performance -- the provision of social insurance. Stronger governance measures are associated with intertemporal smoothing of resources and greater activity in response to negative economic shocks.
Quantifying the effects of harvesting on carbon fluxes and stocks in northern temperate forests
Harvest disturbance has substantial impacts on forest carbon (C) fluxes and stocks. The quantification of these effects is essential for the better understanding of forest C dynamics and informing forest management in the context of global change. We used a process-based forest ecosystem model, PnET-CN, to evaluate how, and by what mechanisms, clear-cuts alter ecosystem C fluxes, aboveground C stocks (AGC), and leaf area index (LAI) in northern temperate forests. We compared C fluxes and stocks predicted by the model and observed at two chronosequences of eddy covariance flux sites for deciduous broadleaf forests (DBF) and evergreen needleleaf forests (ENF) in the Upper Midwest region of northern Wisconsin and Michigan, USA. The average normalized root mean square error (NRMSE) and the Willmott index of agreement (d) for carbon fluxes, LAI, and AGC in the two chronosequences were 20% and 0.90, respectively. Simulated gross primary productivity (GPP) increased with stand age, reaching a maximum (1200â1500 g C mâ2 yrâ1) at 11â30 years of age, and leveled off thereafter (900â1000 g C mâ2 yrâ1). Simulated ecosystem respiration (ER) for both plant functional types (PFTs) was initially as high as 700â1000 g C mâ2 yrâ1 in the first or second year after harvesting, decreased with age (400â800 g C mâ2 yrâ1) before canopy closure at 10â25 years of age, and increased to 800â900 g C mâ2 yrâ1 with stand development after canopy recovery. Simulated net ecosystem productivity (NEP) for both PFTs was initially negative, with net C losses of 400â700 g C mâ2 yrâ1 for 6â17 years after clear-cuts, reaching peak values of 400â600 g C mâ2 yrâ1 at 14â29 years of age, and eventually stabilizing in mature forests (\u3e 60 years old), with a weak C sink (100â200 g C mâ2 yrâ1). The decline of NEP with age was caused by the relative flattening of GPP and gradual increase of ER. ENF recovered more slowly from a net C source to a net sink, and lost more C than DBF. This suggests that in general ENF may be slower to recover to full C assimilation capacity after stand-replacing harvests, arising from the slower development of photosynthesis with stand age. Our model results indicated that increased harvesting intensity would delay the recovery of NEP after clear-cuts, but this had little effect on C dynamics during late succession. Future modeling studies of disturbance effects will benefit from the incorporation of forest population dynamics (e.g., regeneration and mortality) and relationships between age-related model parameters and state variables (e.g., LAI) into the model
Attitudes to self-sampling for HPV among Indian, Pakistani, African-Caribbean and white British women in Manchester, UK
Objective: To examine attitudes to self-sampling for human papillomavirus (HPV) testing among women from contrasting ethnic groups.Setting: Manchester, UK.Methods: Two hundred women of Indian, Pakistani, African-Caribbean and white British origin were recruited from social and community groups to participate in a questionnaire survey. The questionnaire included items on attitudes to self-sampling and intention to use the test.Results: Willingness to try to use the test was high, and women did not foresee religious or cultural barriers to self-sampling; however, a large proportion of women were concerned about doing the test properly. This concern was greatest in the Indian and African-Caribbean groups.Conclusions: Although women's willingness to try self-sampling for HPV is encouraging, worries about carrying out the procedure correctly must be addressed if women are to feel confident about the results of self-sampling methods and reassured by a negative result
Reliable dual-redundant sensor failure detection and identification for the NASA F-8 DFBW aircraft
A technique was developed which provides reliable failure detection and identification (FDI) for a dual redundant subset of the flight control sensors onboard the NASA F-8 digital fly by wire (DFBW) aircraft. The technique was successfully applied to simulated sensor failures on the real time F-8 digital simulator and to sensor failures injected on telemetry data from a test flight of the F-8 DFBW aircraft. For failure identification the technique utilized the analytic redundancy which exists as functional and kinematic relationships among the various quantities being measured by the different control sensor types. The technique can be used not only in a dual redundant sensor system, but also in a more highly redundant system after FDI by conventional voting techniques reduced to two the number of unfailed sensors of a particular type. In addition the technique can be easily extended to the case in which only one sensor of a particular type is available
Decision Making in the Management of Extracapsular Fractures of the Proximal Femur - is the Dynamic Hip Screw the Prevailing Gold Standard?
Currently, approximately half of all hip fractures are extracapsular, with an incidence as high as 50 in 100,000 in some countries. The common classification systems fail to explain the logistics of fracture classification and whether they all behave in the same manner. The Muller AO classification system is a useful platform to delineate stable and unstable fractures. The Dynamic hip screw (DHS) however, has remained the 'gold standard' implant of choice for application in all extracapsular fractures. The DHS relies on the integrity and strength of the lateral femoral wall as well as the postero-medial fragment. An analysis of several studies indicates significant improvements in design and techniques to ensure a better outcome with intramedullary nails. This article reviews the historical trends that helped to evolve the DHS implant as well as discussing if the surgeon should remain content with this implant. We suggest that the gold standard surgical management of extracapsular fractures can, and should, evolve
Tips and Tricks in Extracapsular Hip Fracture Fixation.
Aside from the decision-making in how to fix an extracapsular hip fracture, surgeons must be conversant with systems, implants and how to maximize their potential in the shortest operative time. We present a series of steps used in our unit when performing both DHS and intramedullary nail surgery to avoid the commonest problems and maximize our patients' recovery potential
Stellar Mass to Halo Mass Scaling Relation for X-ray Selected Low Mass Galaxy Clusters and Groups out to Redshift
We present the stellar mass-halo mass scaling relation for 46 X-ray selected
low-mass clusters or groups detected in the XMM-BCS survey with masses
at
redshift . The cluster binding masses are inferred
from the measured X-ray luminosities \Lx, while the stellar masses
of the galaxy populations are estimated using near-infrared imaging from the
SSDF survey and optical imaging from the BCS survey. With the measured \Lx\ and
stellar mass , we determine the best fit stellar mass-halo mass
relation, accounting for selection effects, measurement uncertainties and the
intrinsic scatter in the scaling relation. The resulting mass trend is
, the intrinsic (log-normal) scatter is
, and there is no
significant redshift trend , although
the uncertainties are still large. We also examine within a fixed
projected radius of ~Mpc, showing that it provides a cluster binding mass
proxy with intrinsic scatter of (1 in ). We
compare our scaling relation from the XMM-BCS
clusters with samples of massive, SZE-selected clusters
() and low mass NIR-selected clusters
() at redshift .
After correcting for the known mass measurement systematics in the compared
samples, we find that the scaling relation is in good agreement with the high
redshift samples, suggesting that for both groups and clusters the stellar
content of the galaxy populations within depends strongly on mass but
only weakly on redshift out to .Comment: 15 pages, 10 figures. Accepted for publication in MNRA
Takayasu's disease and pregnancy: Three case studies and a review of the literature
Takayasu's disease is commonest in women of childbearing age. Obstetricians are therefore faced with the dilemma of optimal management in pregnancy. This report of 3 cases suggests that Takayasu's disease is associated with a good maternal and fetal outcome. The basic disease appears to be unaffected by pregnancy
A -ray determination of the Universe's star-formation history
The light emitted by all galaxies over the history of the Universe produces
the extragalactic background light (EBL) at ultraviolet, optical, and infrared
wavelengths. The EBL is a source of opacity for rays via photon-photon
interactions, leaving an imprint in the spectra of distant -ray
sources. We measure this attenuation using {739} active galaxies and one
gamma-ray burst detected by the {\it Fermi} Large Area Telescope. This allows
us to reconstruct the evolution of the EBL and determine the star-formation
history of the Universe over 90\% of cosmic time. Our star-formation history is
consistent with independent measurements from galaxy surveys, peaking at
redshift . Upper limits of the EBL at the epoch of re-ionization
suggest a turnover in the abundance of faint galaxies at .Comment: Published on Science. This is the authors' version of the manuscrip
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