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Acceptable Risk (acceptable + risk)

Distribution by Scientific Domains

Medical Sciences	38%
Engineering	38%

Selected Abstracts

Comparative analysis of three user equilibrium models under stochastic demand

JOURNAL OF ADVANCED TRANSPORTATION, Issue 3 2008
Zhong Zhou
Abstract Recent empirical studies on the value of time and reliability reveal that travel time variability plays an important role on travelers' route choice decision process. It can be considered as a risk to travelers making a trip. Therefore, travelers are not only interested in saving their travel time but also in reducing their risk. Typically, risk can be represented by two different aspects: acceptable risk and unacceptable risk. Acceptable risk refers to the reliability aspect of acceptable travel time, which is defined as the average travel time plus the acceptable additional time (or buffer time) needed to ensure more frequent on-time arrivals, while unacceptable risk refers to the unreliability aspect of unacceptable late arrivals (though infrequent) that have a travel time excessively higher than the acceptable travel time. Most research in the network equilibrium based approach to modeling travel time variability ignores the unreliability aspect of unacceptable late arrivals. This paper examines the effects of both reliability and unreliability aspects in a network equilibrium framework. Specifically, the traditional user equilibrium model, the demand driven travel time reliability-based user equilibrium model, and the ,-reliable mean-excess travel time user equilibrium model are considered in the investigation under an uncertain environment due to stochastic travel demand. Numerical results are presented to examine how these models handle risk under travel time variability. [source]

Crack,heroin speedball injection and its implications for vein care: qualitative study

ADDICTION, Issue 11 2007
Tim Rhodes
ABSTRACT Background We report on an exploratory qualitative study investigating drug injectors' narratives of vein damage and groin (femoral vein) injection associated with the injection of crack,heroin speedball. Methods We undertook 44 in-depth qualitative interviews among injectors of crack,heroin speedball in Bristol and London, England, in 2006. Findings The data suggest an emerging culture of crack-based speedball injection. Injectors' narratives link speedball injection with shifts towards groin injection articulated as an acceptable risk, and not merely as a last resort in the face of increased vein deterioration associated with speedball. Accounts of vein damage linked to speedball emphasize ,missed hits' related to the local anaesthetic action of crack, the excess use of citric in the preparation of speedball injections and ,flushing' when making a hit. We find that groin injection persists despite an awareness of health risks and medical complications. Conclusions We emphasize an urgent need for reviewing harm reduction in relation to vein care in the context of shifts to crack-based speedball injection, and the use of the femoral vein, among UK injectors. There is an additional need for interventions to promote safer groin and speedball injecting as well as to prevent transitions toward groin and crack injection. [source]

Comparative analysis of three user equilibrium models under stochastic demand

Left Ventricular Reconstruction for Ischemic Cardiomyopathy

JOURNAL OF CARDIAC SURGERY, Issue 3 2002
Vincent Dor M.D.
The technique is conducted under a totally arrested heart; coronary revascularization is accomplished first. The mitral valve is checked by TEE and repaired if necessary. Endocardectomy and cryotherapy are used in case of ventricular tachycardia. At the limit between scarred and normal tissue, a continuous suture is tied on a balloon inflated at the theoretical diastolic volume of the patient, and a patch is fixed inside the ventricle. Autologous tissue can be also used. The experience of the author is more than 1000 cases since 1984. The global hospital mortality of the whole series is 7.3%, and 13% in patients with very poor ejection fraction (<30%). In the series of the last 3 years, these mortality rates are 4.8% and 7.9%, respectively. Both geometry and performances of the LV are improved, and the mean increase of ejection fraction is between 10 and 15 points. Three causes can explain delayed impairment; continuum in remodeling, lack in diastolic capacity, or absence of mitral repair. After an infarct, with or without successful coronary recanalization, that leaves a large asynergic scarred ventricle (50% of LV circumference), LVR is recommended to avoid or prevent permanent congestive heart failure with global dilatation. In end-stage ischemic cardiomyopathy with congestive heart failure, and poor response to full medical therapy, LVR, with acceptable risk, could slow down the remodeling and avoid or delay heart transplantation. [source]

How should the risk associated with the introduction of biological control agents be estimated?

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010
Earl D. McCoy
1Florida has an exceptional burden of invasive species. The history of the classical biological control of invasive arthropod pest species in the region largely is one of inadequate pre-release testing for nontarget effects. 2A recent analysis indicated that a substantial risk of nontarget effects may exist in Florida, although the risk appears to be confined to a relatively small group of species within approximately ten families and documented cases of nontarget effects are rare, despite previous risky practices. 3Great progress has been made recently in creating an organized framework for dealing with the uncertainty accompanying biological control importations in Florida and elsewhere. We suggest some ways in which balancing the risks and associated costs of releasing a biological control agent against the risks and associated costs of not releasing the agent may be improved. 4Ultimately, experts will need to set some level of acceptable risk, and the ,precautionary principle' has been advanced to guide this process. As it stands, however, the precautionary principle applied to biological control falls short as a guide because it does not provide a prescription for action. 5Florida case histories clearly illustrate both the complexity and urgency related to developing a prescription for action. [source]

Warfighter Needs in the 21st Century: Linking Fleet Operations to Required Capabilities

NAVAL ENGINEERS JOURNAL, Issue 4 2000
Capt. V.A. Myer USNR (Ret.)
ABSTRACT What the warfighter needs is not what he is getting in terms of responsiveness to the emerging threat, interoperability among systems, and systems readiness and training. This disconnect between Fleet operations and the acquisition requirements process is becoming more pronounced as systems grow larger and more complex and as warflghting becomes more joint Knowing what the warfighter wants and how he envisions using it in a concept of operations is fundamental to the requirements process. The source of this information is the commander in chief's (CINC's) operations plan (OPLAN), which contains the concept of operations (CONOPS) for each warfighting theater. It is critical that the CONOPS be used as the basis for determining performance requirements, because it contains the military judgment, context, and authority of the theater CINC. The defunct Arsenal Ship program, which was rightly vetoed by the theater CINCs because it would not meet their warfighting needs at acceptable risk, is a recent example of the mismatch between what is being asked for and what is being provided. [source]

Risk Management in Total System Ship Design

NAVAL ENGINEERS JOURNAL, Issue 4 2000
C. F. Barker P.E.
ABSTRACT Ships are being designed with an increased emphasis on reduced life cycle costs, obtained through means such as reduced crew size, increased automation, and adoption of commercial practices. Ship cost is closely related to the likelihood and consequence of future events, or risk. Ship designers must have tools to assess and manage risks to obtain cost-effective designs. Risk assumptions were built into prescriptive standards, but performance standards are now being used. Ships systems built to varying degrees of acceptable risk are not cost-effective. Underdesigns and overdesigns will result, and the ship ends up only as strong as its "weakest link." The authors propose that the top-down risk management methodology that is currently used for commercial ships be considered for use by naval ship designers in conjunction with both the traditional ship design spiral and the total systems ship design concept. The IMO-endorsed formal safety assessment (FSA) methodology was designed for marine systems. By adopting the FSA approach the Navy will benefit from existing lessons-learned, and will have a smoother transition into the application of commercial standards when the ship is built. [source]

The development of risk criteria for high severity low frequency events,

PROCESS SAFETY PROGRESS, Issue 1 2009
Fred Henselwood
Abstract Quantitative risk assessments (QRAs) are used within the field of process safety to decide the allocation of resources and risk reduction investments. Typically risk assessments involve the evaluation of probabilistic measures that estimate the average expected value for the situation being considered across a range of potential outcomes. The resulting expected value is then used to determine if a situation represents an acceptable or unacceptable risk based on a threshold value allotted to the risk. This approach often gives guidance that is at odds with the thoughts and behaviors of some stakeholders as illustrated by the "but what if it does happen?" type of question. This inconsistency results from the inherent limitation associated with expected value approaches in that the methodology is based on whether or not a mean assessed risk represents an acceptable risk while overlooking the possibility that a single scenario could represent an intolerable event. This article looks at an adjustment to traditional QRAs so as to assess both the acceptability of risk and the tolerability of the associated consequences relative to risk criteria. These adjustments have been found to better represent stakeholder perceptions of risk, more closely relate risk tolerance to corporate values and resources, and to better justify the use of various risk transfer strategies. © 2008 American Institute of Chemical Engineers Process Saf Prog, 2009 [source]

THYROIDECTOMY IS SAFE AND EFFECTIVE FOR RETROSTERNAL GOITRE

ANZ JOURNAL OF SURGERY, Issue 4 2006
Ajay Chauhan
Background: Retrosternal goitre was defined as any thyroid enlargement identified below the thoracic inlet at operation, with the patient's neck held in extension. The aim of this study was to determine the characteristics of the patients, the goitres, the surgery and its morbidity (including tracheomalacia, recurrent laryngeal nerve palsy and hypocalcaemia) and the incidence of malignancy in order to establish guidelines for managing patients with a retrosternal goitre. Methods: Data were collected prospectively on all thyroidectomies carried out by a single surgeon over 14 years. Patients underwent appropriate preoperative assessment and thyroidectomy was carried out using a standardized capsular dissection technique. There were 199 cases of retrosternal extension. Results: Retrosternal extension was significantly more common on the left side than on the right side (ratio 3:2, P < 0.05). Most patients (83.4%) had significant symptoms that were relieved by surgery. Of the 199 thyroidectomies, none required a sternal split. The rate of malignancy was low (2.5%). Postoperative morbidity was 30%, the majority being asymptomatic temporary hypocalcaemia. There were no patients with permanent recurrent laryngeal nerve palsies or permanent hypoparathyroidism. There was one case of tracheomalacia. There was no death. Conclusion: Retrosternal goitre is a frequently symptomatic condition, with a low but definite rate of malignancy. Surgery is usually possible through a cervical incision and with an acceptable risk of significant morbidity. Thyroidectomy should be recommended as the treatment of choice. [source]

Navigating ethical discharge planning: A case study in older adult rehabilitation

AUSTRALIAN OCCUPATIONAL THERAPY JOURNAL, Issue 1 2010
Evelyne Durocher
Background:, Ethical issues are becoming more complex as individuals live longer with increased disability and medical needs. This article elucidates common ethical issues encountered in discharge planning with older adults. Methods:, We conducted normative ethical analysis of a clinical case using methods of philosophical inquiry, including thick description, reflexivity, conceptual clarification and examination of competing arguments for internal consistency. Results:, The analysis demonstrates how health-care teams struggle to balance protection from harm while honouring informed choices. We argue that ethical discharge planning requires judicious identification of client values, even if these conflict with team determinations of best interests. Conclusion:, Dialogue is needed to identify risks, help clients determine their personal level of acceptable risk and determine provisions to minimise risks. [source]

Epilepsy and driving: considerations on how eligibility should be decided

ACTA NEUROLOGICA SCANDINAVICA, Issue 2010
R. Lossius
Lossius R, Kinge E, Nakken KO. Epilepsy and driving: considerations on how eligibility should be decided. Acta Neurol Scand: 2010: 122 (Suppl. 190): 67,71. © 2010 John Wiley & Sons A/S. Although few neurologists are formally trained in traffic medicine, they are frequently asked to assess whether a patient is medically fit to drive. For patients with epilepsy, the physician must assess the risk of the patient having a seizure while driving, and decide what is an acceptable risk. The legislation on this subject is aiming at finding a reasonable balance between two important considerations: public safety and a patient's individual need to drive. For the neurologist to explain and put into practice the legislation may be a demanding task and a challenge to the doctor,patient alliance. The decision on driving capability should be tailored to the individual patient and based on careful evaluation and informed judgement. In Norway, to qualify for a driver's license, a seizure-free interval of at least 12 months is currently required for group 1 drivers (passenger cars), whereas group 2 drivers (heavy motor vehicles, commercial driving) must have been seizure-free for at least 10 years and not have experienced epileptic seizures from the age of 18 years. Norwegian physicians are obliged to report patients with seizures to driving authorities, although this is an unpopular rule. In reviewing the available literature, it is apparent that despite there being relatively few sound studies, the risks of car accidents among persons with epilepsy may previously have been overestimated. [source]

Environmental risk assessment of human pharmaceuticals in the European Union: A case study with the ,-blocker atenolol

INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue S1 2010
Anette Küster
Abstract ,-Adrenergic receptor blockers (,-blockers) are applied to treat high blood pressure, ischemic heart disease, and heart rhythm disturbances. Due to their widespread use and limited human metabolism, ,-blockers are widely detected in sewage effluents and surface waters. ,-Adrenergic receptors have been characterized in fish and other aquatic animals, so it can be expected that physiological processes regulated by these receptors in wild animals may be affected by the presence of ,-blockers. Because ecotoxicological data on ,-blockers are scarce, it was decided to choose the ,-blocker atenolol as a case study pharmaceutical within the project ERAPharm. A starting point for the assessment of potential environmental risks was the European guideline on the environmental risk assessment of medicinal products for human use. In Phase I of the risk assessment, the initial predicted environmental concentration (PEC) of atenolol in surface water (500,ng L,1) exceeded the action limit of 10,ng L,1. Thus, a Phase II risk assessment was conducted showing acceptable risks for surface water, for groundwater, and for aquatic microorganisms. Furthermore, atenolol showed a low potential for bioaccumulation as indicated by its low lipophilicity (log KOW,=,0.16), a low potential for exposure of the terrestrial compartment via sludge (log KOC,=,2.17), and a low affinity for sorption to the sediment. Thus, the risk assessment according to Phase II-Tier A did not reveal any unacceptable risk for atenolol. Beyond the requirements of the guideline, additional data on effects and fate were generated within ERAPharm. A 2-generation reproduction test with the waterflea Daphnia magna resulted in the most sensitive no-observed-effect concentration (NOEC) of 1.8,mg L,1. However, even with this NOEC, a risk quotient of 0.003 was calculated, which is still well below the risk threshold limit of 1. Additional studies confirm the outcome of the environmental risk assessment according to EMEA/CHMP (2006). However, atenolol should not be considered as representative for other ,-blockers, such as metoprolol, oxprenolol, and propranolol, some of which show significantly different physicochemical characteristics and varying toxicological profiles in mammalian studies. Integr Environ Assess Manag 2010;6:514,523. © 2009 SETAC [source]

Citizen Response to Disasters: a Survey of Literature and Some Practical Implications

JOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 3 2004
I. Helsloot
It is most likely that the modern citizen responds to disasters in the same fashion as his ancestor. Contrary to widespread belief, citizens do not panic in disaster situations. In fact, research into different aspects of citizen response shows that most citizens act in a rather rational way. Indeed, citizens often prove to be the most effective kind of emergency personnel. Disaster evaluations invariably show that most lives are actually saved by the ,average' citizen. On the other hand, it seems little can be done to improve citizen preparedness. A modern western citizen is not likely to invest time or money in preparing for ,acceptable' risks. The above results stem for the greater part from research already conducted as long ago as the nineteen-eighties. Limitations and implications however seem as yet unclear. One important limitation is the cultural bias in most studies. One important implication is that in western countries government should step in to improve citizen response by preparing to facilitate it in times of disaster. [source]