Multiple-Cause

There are multiple causes of diabetes. Whereas the molecular bases of some forms of diabetes are well understood, in many cases etiologies are unknown. It is customary to divide diabetes into two main forms insulin-dependent diabetes mellitus (IDDM), also referred to as Type I or juvenile-onset diabetes, and noninsulin-dependent diabetes mellitus (NIDDM), also called Type II or maturity-onset diabetes (3). 

Watanahe, K. and D.M. Himmelhlau, Incipient Fault Diagnosis of Nonlinear Processes with Multiple Causes of Faults, Chemical Engineeiing... 

A fault may interfere with the effectiveness or the func tioning of the unit (Watanabe, K., and D.M. Himmelblau, Incipient Fault Diagnosis of Nonhnear Processes with Multiple Causes of Faults, Chemical Engineering Science, 39(3), 1984, 491-508). The first question addresses the effectiveness. The second two address the functioning. Fault detection is a unit monitoring activity, done automatically or periodically, to determine whether the unit operation has changed. 

During the PHEA stage, the analyst has to identify likely human errors and possible ways of error detection and recovery. The PHEA prompts the analyst to examine the main performance-influencing factors (PIFs) (see Chapter 3) which can contribute to critical errors. All the task steps at the bottom level of the HTA are analyzed in turn to identify likely error modes, their potential for recovery, their safety or quality consequences, and the main performance-influencing factors (PIFs) which can give rise to these errors. In this case study, credible errors were found for the majority of the task steps and each error had multiple causes. An analysis of two operations from the HTA is presented to illustrate the outputs of the PHEA. Figure 7.12 shows a PHEA of the two following tasks Receive instructions to pump and Reset system. 

Wagenaar, W. A., c Groeneweg, J. (1987). Accidents at Sea Multiple Causes and Impossible Consequences. International [ournal of Man-Machine Studies 27, 587-598. 

Mode of action Interferes with bacterial cell wall synthesis during active multiplication, causing cell wall death and resultant bactericidal activity Inhibits bacterial cell wall synthesis by binding to one or more of the penicillin-binding proteins, which in turn inhibit the final transpeptidation step of peptidoglycan synthesis in bacterial cell walls bacteria usually lyse from ongoing autolytic enzyme activity... 

Figure 5.7 Comparison of four-parameter fy-maxi mum, v-minimum. IC50, and h) and two-parameter (IC50 and h) fits of non-ideal concentration-response data. In panels A and B the data indicate a nonzero plateau at low inhibitor concentration that might reflect a low-amplitude, high-affinity second binding interaction. In panels C and D the data indicate a plateau at high inhibitor concentration that does not achieve full inhibition of the enzyme. There could be multiple causes of behavior such as that seen in panels C and D. One common cause is low compound solubility at the higher concentrations used to construct the concentration-response plot. Note that the discordance between the experimental data and the expected behavior is most immediately apparent in the plots that are fitted by the two-parameter equation.

There is still a lack of knowledge on ecosystem services integrated concepts. The ecology of recovery (for instance, how long does recovery of a measure or due to a measure take When does a system recover ) is also a concept still not well understood. For instance, for instance, the most important factor for the recovery of a population may be difficult to identify since there can be multiple causes involved. Studies discriminating these are scarce, especially comparisons of the significance of the species traits and of its interactions with other species for its ability to recover. 

Process risk is defined by the frequency of the occurrence and the potential consequence severity of the process hazard. To define the frequency, the initiating causes (e.g., single causes or multiple causes and conditions) are identified for each process hazard, and their frequency of occurrence is estimated. The consequence severity is the logical conclusion to the propagation of the process hazard if no protection layers are implemented as barriers to the event. 

Identifying causes is one of the primary objectives of the entire investigation process. Initial selection of the root cause determination process will most likely require some special attention to the concepts of multiple causes (especially when dealing with reactive chemistry) and to underlying system-related causes. 

When exploring the cause of an ADR, many syndromes and condihons can have multiple causes that occur in only a small percentage of fhe population and which often have vague... 

It allows for the development of models of complex engineering systems and management structures. These models can be analyzed for inter-relationships between individual elements and the overall system function. Theoretically, there could be as many causes of an incident as there are system components. The term multiple-cause theory, coined by Peterson, is often used instead of system theory. 

Progressive companies use a more structured and comprehensive team approach to identify root causes. Scientific principles and concepts are applied to determine root causes and make recommendations to prevent recurrence. Effective investigations should use tested data analysis tools and methodologies to seek the identification of multiple causes. To be repeatable, the investigation should use a systematic approach, which may also be prescriptive. As a rule, the benefits of this systematic approach result from two actions ... 

The earliest logic trees were based on engineering fault tree analysis methods. Today, companies use a number of variations or combinations of logic trees and call them by different names, such as Why Tree,< 9) Causal Tree,(20,21) Cause and Effect Logic Diagram (CELD),<22) and Multiple-Cause, Systems-Oriented Incident Investigation (MCS011).<23,24) tools have more similarities than differences. 

It improves the quality of investigations by directing the focus past the immediate surface causes to the underlying root causes and management system failures, and mandating a search for multiple causes. 

Causal Trees were developed in an effort to use the principles of deductive logic found in Fault Tree but make it more user-friendly. Originally, private companies developed the Causal Tree Method (CTM) for safety, process safety, and environmental incident investigations applications. Rhone-Poulenc, for example, was an early user.<20.21) Multiple-Cause Systems Oriented Incident Investigation (MCSOfl) is another name for the CTM. At this time, most companies use simplified versions of fault trees for complex incident investigations. 

MULTIPLE CAUSES - Most current methods recognize the concept of multiple root causes. 

Dowell, A. M. Guidelines for Systems Oriented Multiple Cause Incident Investigations. Deer Park, TX Rohm and Haas Texas Inc. Risk Analysis Department, 1990. 

There are usually multiple causes of an incident, with multiple people and occurrences contrihuting to its evolution. The Hazard-Barrier-Target (HBT) concept described in Chapter 3 provides an interesting view of the multiple-cause or system theory. 

Process safety incidents are invariably the result of multiple causes, which can usually be categorized into three types ... 

SOME GUIDING QUESTIONS FOR MULTIPLE CAUSE DETERMINATION. 

The multiple causes leading to an incident are clearly illustrated. 

The diagram can assist the overall methodology to identify multiple causes, when used in conjunction with logic trees or predefined trees. 

The team must also consider the likelihood of the incident being repeated, which is a major reason for pursuing near-miss incident investigations to their conclusion and learning value. This reminder should be given at the beginning of the multiple cause determination meeting and repeated as necessary. 

After the most likely scenario has been identified and the logic tree developed, the incident investigation team now reaches the stage of searching out the system-related multiple causes. An accompanying challenge is deciding when to stop further development of each branch of the tree. 

The tool helps the investigator to understand and focus on the failed harriers, which are normally identified as causal factors. These failed harriers may need to he strengthened, replaced, or supplemented, especially where weak administrative controls are highlighted. Even successful barriers that prevented more serious consequences may require reinforcement. Therefore, barrier analysis can give the investigator valuable insights into how the incident happened and some of the multiple causes that need corrective action to prevent recurrence. 

A timeline or sequence diagram is first developed, and then causal factors identified. Care should be taken to ensure that the checklist is not used too early. Be sure to determine what happened and how it happened before determining why it happened. Otherwise, the team will think that they have identified the right root cause(s), when in reality only one or two of several multiple causes have been determined. The causal factors are then applied one at a time to each page of the checklist(s) to identify relevant root causes. Those pages that are not relevant to the particular incident of interest are discarded. Similar quality assurance checks should be applied as those described for predefined trees. 

The key issue is that causes addressed in recommendations must address system-hased issues, and the team must always look for multiple causes and corrections. 

The process of developing recommendations is summarized in Figure 10-1. Starting with the set of multiple causes determined previously in Chapter 9, each cause is evaluated individually to consider actions that would prevent (or satisfactorily mitigate) a recurrence. Ideally, each recommendation should cover just one item and spell out precisely what action is recommended. 

The next activity in the sequence is to check for completeness, such as, Have all the identified causes been addressed The incident investigation team should remember that the multiple causes are not all necessarily located at the bottom of the logic tree structure. Sometimes causes may be... 

Safety Supervisor (trained and expert in the multiple-cause sys-tems-oriented incident investigation methodology)... 

MCSOII Multiple-Cause, Systems-Oriented Incident Investigation... 

When Fernandez et al. studied partially polymerized Series P PB/PS systems, SANS results yielded peaks in the scattering patterns, see Figure 14 [ ]. Early attempts at understanding these peaks were troublesome due to the multiple causes for such peaks. Later, similar peaks were observed in another set of samples, which were partially swollen, then fully reacted (series S) by An et al. [41], but, in this case, shoulders instead of distinct maximum were observed (Figure 15). In both cases, such maximum or shoulders appeared at mid-range compositions, then were replaced by smoothly decreasing curves on further polymerization of monomer II. 

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