3,347 research outputs found
VPSIRR (Vulnerability - Pressure - State - Impact - Risk And Response): An Approach To Determine The Condition Of Estuaries And To Assess Where Management Responses Are
Estuaries are highly variable in terms of type and geomorphic classification. The condition of these systems is often a reflection of activities taking place in their catchments and the susceptibility of these systems to each particular pressure. Effective management intervention can be achieved when there is an understanding of the current condition of the estuary or component of the estuary and of the pressures likely to affect them. If this can be linked to the susceptibility of the estuary to the pressure (risk), the management activity can be prioritised. A framework based on the Pressure-State-Impact-Response model, but which also includes the vulnerability of the system to each of the pressures has been developed. A key feature of this framework is that the links between indicators of pressure, state and impact are clearly identified ensuring that only indicators relevant to the local situation are selected. In addition, a risk assessment process has been developed. This approach is called a VPSIRR (Vulnerability - Pressure - State - Impact - Risk - Response)approach. Application of this method increases the likelihood of being able to identify the causes of any observed changes in condition, making it easier to identify appropriate management actions. It also enables information to be provided to the community in a user-friendly manner. We have developed a user friendly computer package which enables the risk that each estuary is under from various pressures to be assessed and linked to condition. The package enables the certainty about various data used to inform the process, to be reported. Importantly, the package enables indicator information to be updated as better information becomes available. It also enables new indicator information to be incorporated into the software should better knowledge become available. This component would only be made available to software administrators. The package produces a colour coded and numeric report card comprising of 5 colours or numbers which is designed to be easily understood and interpreted by users from a variety of backgrounds. The software can be used to inform managers of where to focus management investment, but can also be used to educate people about natural resource issues and the implications of different catchment and estuary based activities. Fact sheets imbedded within the software provide details about the various indicators. These include how to collect data and where necessary, how to analyse them in order to use the software. The fact sheets also provide information on management responses to a variety of issues
A computationally engineered RAS rheostat reveals RAS-ERK signaling dynamics.
Synthetic protein switches controlled with user-defined inputs are powerful tools for studying and controlling dynamic cellular processes. To date, these approaches have relied primarily on intermolecular regulation. Here we report a computationally guided framework for engineering intramolecular regulation of protein function. We utilize this framework to develop chemically inducible activator of RAS (CIAR), a single-component RAS rheostat that directly activates endogenous RAS in response to a small molecule. Using CIAR, we show that direct RAS activation elicits markedly different RAS-ERK signaling dynamics from growth factor stimulation, and that these dynamics differ among cell types. We also found that the clinically approved RAF inhibitor vemurafenib potently primes cells to respond to direct wild-type RAS activation. These results demonstrate the utility of CIAR for quantitatively interrogating RAS signaling. Finally, we demonstrate the general utility of our approach in design of intramolecularly regulated protein tools by applying it to the Rho family of guanine nucleotide exchange factors
Risk-shifting Through Issuer Liability and Corporate Monitoring
This article explores how issuer liability re-allocates fraud risk and how risk allocation may reduce the incidence of fraud. In the US, the apparent absence of individual liability of officeholders and insufficient monitoring by insurers under-mine the potential deterrent effect of securities litigation. The underlying reasons why both mechanisms remain ineffective are collective action problems under the prevailing dispersed ownership structure, which eliminates the incentives to moni-tor set by issuer liability. This article suggests that issuer liability could potentially have a stronger deterrent effect when it shifts risk to individuals or entities holding a larger financial stake. Thus, it would enlist large shareholders in monitoring in much of Europe. The same risk-shifting effect also has implications for the debate about the relationship between securities litigation and creditor interests. Credi-tors’ claims should not be given precedence over claims of defrauded investors (e.g., because of the capital maintenance principle), since bearing some of the fraud risk will more strongly incentivise large creditors, such as banks, to monitor the firm in jurisdictions where corporate debt is relatively concentrated
Fusion of secretory vesicles isolated from rat liver
Secretory vesicles isolated from rat liver were found to fuse after exposure to Ca2+. Vescle fusion is characterized by the occurrence of twinned vesicles with a continuous cleavage plane between two vesicles in freeze-fracture electron microscopy. The number of fused vesicles increases with increasing Ca2+-concentrations and is half maximal around 10–6 m. Other divalent cations (Ba2+, Sr2+, and Mg2+) were ineffective. Mg2+ inhibits Ca2+-induced fusion. Therefore, the fusion of secretory vesiclesin vitro is Ca2+ specific and exhibits properties similar to the exocytotic process of various secretory cells.
Various substances affecting secretionin vivo (microtubular inhibitors, local anethetics, ionophores) were tested for their effect on membrane fusion in our system.
The fusion of isolated secretory vesicles from liver was found to differ from that of pure phospholipid membranes in its temperature dependence, in its much lower requirement for Ca2+, and in its Ca2+-specificity. Chemical and enzymatic modifications of the vesicle membrane indicate that glycoproteins may account for these differences
Markov analysis of stochastic resonance in a periodically driven integrate-fire neuron
We model the dynamics of the leaky integrate-fire neuron under periodic
stimulation as a Markov process with respect to the stimulus phase. This avoids
the unrealistic assumption of a stimulus reset after each spike made in earlier
work and thus solves the long-standing reset problem. The neuron exhibits
stochastic resonance, both with respect to input noise intensity and stimulus
frequency. The latter resonance arises by matching the stimulus frequency to
the refractory time of the neuron. The Markov approach can be generalized to
other periodically driven stochastic processes containing a reset mechanism.Comment: 23 pages, 10 figure
The sound of street corner society: UK grime music as ethnography
This article explores the ways in which popular music can be linked to ethnography. While there is a tradition of connecting popular music with sociology, this article posits a further resonance that is not so much theoretical as methodological. The article suggests that forms of contemporary popular music parallel key facets of ethnography, not simply in terms of sociological analysis, but with regard to popular music as an ethnographic resource, as ‘data’, and as the reflexive expression of Paul Willis’ conception of the ‘ethnographic imagination’; and the article argues that contemporary British hip-hop in the form of ‘grime’ is a potent exemplar. This is due to the resolutely cultural, spatial nature of grime music: a factor that marks out grime as a distinctive musical genre and a distinctive ethnographic form, as it is an experientially rooted music about urban locations, made from within those urban locations
Using ordinal logistic regression to evaluate the performance of laser-Doppler predictions of burn-healing time
Background
Laser-Doppler imaging (LDI) of cutaneous blood flow is beginning to be used by burn surgeons to predict the healing time of burn wounds; predicted healing time is used to determine wound treatment as either dressings or surgery. In this paper, we do a statistical analysis of the performance of the technique.
Methods
We used data from a study carried out by five burn centers: LDI was done once between days 2 to 5 post burn, and healing was assessed at both 14 days and 21 days post burn. Random-effects ordinal logistic regression and other models such as the continuation ratio model were used to model healing-time as a function of the LDI data, and of demographic and wound history variables. Statistical methods were also used to study the false-color palette, which enables the laser-Doppler imager to be used by clinicians as a decision-support tool.
Results
Overall performance is that diagnoses are over 90% correct. Related questions addressed were what was the best blood flow summary statistic and whether, given the blood flow measurements, demographic and observational variables had any additional predictive power (age, sex, race, % total body surface area burned (%TBSA), site and cause of burn, day of LDI scan, burn center). It was found that mean laser-Doppler flux over a wound area was the best statistic, and that, given the same mean flux, women recover slightly more slowly than men. Further, the likely degradation in predictive performance on moving to a patient group with larger %TBSA than those in the data sample was studied, and shown to be small.
Conclusion
Modeling healing time is a complex statistical problem, with random effects due to multiple burn areas per individual, and censoring caused by patients missing hospital visits and undergoing surgery. This analysis applies state-of-the art statistical methods such as the bootstrap and permutation tests to a medical problem of topical interest. New medical findings are that age and %TBSA are not important predictors of healing time when the LDI results are known, whereas gender does influence recovery time, even when blood flow is controlled for.
The conclusion regarding the palette is that an optimum three-color palette can be chosen 'automatically', but the optimum choice of a 5-color palette cannot be made solely by optimizing the percentage of correct diagnoses
Longitudinal-Transverse Separations of Structure Functions at Low for Hydrogen and Deuterium
We report on a study of the longitudinal to transverse cross section ratio,
, at low values of and , as determined from
inclusive inelastic electron-hydrogen and electron-deuterium scattering data
from Jefferson Lab Hall C spanning the four-momentum transfer range 0.06 GeV. Even at the lowest values of , remains
nearly constant and does not disappear with decreasing , as expected. We
find a nearly identical behaviour for hydrogen and deuterium.Comment: 4 pages, 2 gigure
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