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Substantial Difficulties (substantial + difficulty)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Regularized sequentially linear saw-tooth softening model

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 7-8 2004
Jan G. Rots
Abstract After a brief discussion on crack models, it is demonstrated that cracking is often accompanied by snaps and jumps in the load,displacement response which complicate the analysis. This paper provides a solution by simplifying non-linear crack models into sequentially linear saw-tooth models, either saw-tooth tension-softening for unreinforced material or saw-tooth tension-stiffening for reinforced material. A linear analysis is performed, the most critical element is traced, the stiffness and strength of that element are reduced according to the saw-tooth curve, and the process is repeated. This approach circumvents the use of incremental,iterative procedures and negative stiffness moduli and is inherently stable. The main part of the paper is devoted to a regularization procedure that provides mesh-size objectivity of the saw-tooth model. The procedure is similar to the one commonly used in the smeared crack framework but, in addition, both the initial tensile strength and the ultimate strain are rescaled. In this way, the dissipated fracture energy is invariant with respect not only to the mesh size, but also to the number of saw-teeth adopted to discretize the softening branch. Finally, the potential of the model for large-scale fracture analysis is demonstrated. A masonry façade subjected to tunnelling induced settlements is analysed. The very sharp snap-backs associated with brittle fracture of the façade automatically emerge with sequentially linear analysis, whereas non-linear analysis of the façade using smeared or discrete crack models shows substantial difficulties despite the use of arc-length schemes. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Social health insurance in developing countries: A continuing challenge

INTERNATIONAL SOCIAL SECURITY REVIEW, Issue 2 2002
Guy Carrin
This paper addresses the issue of the feasibility of "social" health insurance (SHI) in developing countries. SHI aims at protecting all population groups against financial risks due to illness. There are substantial difficulties in implementation, however, due to lack of debate and consensus about the extent of financial solidarity, problems with health service delivery, and insufficient managerial capacity. The transition to universal coverage is likely to take many years, but it can be speeded up. Adopting a "family" approach to financial protection, sustained financial support from governments and donors, and deconcentrating the development of SHI may slash several years from the time needed to achieve full universal protection against healthcare costs. [source]

The possible factors affecting suicide attempts in the different phases of the menstrual cycle

PSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 5 2004
ALI ÇAYKÖYlÜ md
Abstract, This study was designed to investigate whether there is a relationship between the menstrual cycle and suicide attempts, and to determine the factors affecting suicide attempts in different phases of the menstrual cycle. The study sample included 52 women who were admitted to the emergency room because of a suicide attempt. The incidence of suicide attempts in menstrual follicular phase (MFP) was significantly higher than in other phases. No significant difference of socio-demographic and clinical characteristics was observed between MFP and the other phases. Also, hormone levels of patients who attempted suicide were not different from those of healthy control subjects. In spite of the fact that suicide attempts were often made in MFP, there was substantial difficulty in explaining why this frequency was different than other phases. Furthermore, the event may be linked to low estrogen and progesterone levels in this phase. It has, however, been thought that hormonal effects cannot be responsible alone for suicide attempts. [source]

Review of singleton fetal and neonatal deaths associated with cranial trauma and cephalic delivery during a national intrapartum-related confidential enquiry

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 5 2005
Fidelma O'Mahony
Objective To review delivery details of intrapartum-related fetal and neonatal deaths with singleton cephalic presentation and birthweight of 2500 g or more in which traumatic cranial or cervical spine injury or substantial difficulty at delivery of the head was a dominant feature. Design Review of freestyle summary reports and standard questionnaire responses submitted to the national secretariat for the Confidential Enquiry into Stillbirths and Death in Infancy (CESDI) during the 1994/1995 intrapartum-related mortality enquiry following regional multidisciplinary panel review. Setting United Kingdom. Sample Of the 873 cases of intrapartum-related deaths reported in the 1994,1995 national enquiry, 709 weighed more than 2499 g. Reports from 181 (89 from 1994 and 92 from 1995) with a chance of meeting criteria for cranial or cervical trauma as significant contributors to death were examined in detail. Thirty-seven were judged to meet the criteria stated in the objectives (23 from 1994 and 14 from 1995) and form the basis for this review. Methods Electronic and hand search of CESDI records relating to intrapartum-related deaths. Main outcome measures Intrapartum events and features of care. Results There was evidence of fetal compromise present before birth in 33 of the 37 (89%) study group cases reviewed. One delivery was performed vaginally without instrumentation, and in one there was no attempt at vaginal delivery before caesarean section (CS) in the second stage of labour. Twenty-four cases (65%) were delivered vaginally and 11 (30%) by CS after failure to deliver vaginally with instruments. A single instrument was used in six cases of vaginal delivery (four ventouse and two Kjelland's forceps). At least two separate attempts with different instruments were made in 24 cases. Overall, the ventouse was used in 27 cases and forceps in 29 cases. In six cases, three separate attempts were made with at least two different instruments, all of which included use of ventouse. The grade of operator was recorded in 27 cases. Of these, a consultant obstetrician was present at only one delivery and no consultant was recorded to have made the first attempt to deliver a baby. In six cases, shoulder dystocia was also reported. Conclusions This study suggests a lower incidence of death from difficult cephalic delivery and cranial trauma than previously reported. The CESDI studies were believed to have achieved high levels of ascertainment for all intrapartum-related deaths from which the cases reported here were selected. Strictly applied entry criteria used in this study could have restricted the number of cases considered as could limited in vivo or postmortem investigations and lack of detailed autopsy. When cranial traumatic injury was observed, it was almost always associated with physical difficulty at delivery and the use of instruments. The use of ventouse as the primary or only instrument did not prevent this outcome. Some injuries occurred apparently without evidence of unreasonable force, but poorly judged persistence with attempts at vaginal delivery in the presence of failure to progress or signs of fetal compromise were the main contributory factor regardless of which instruments were used. [source]