An ancestral molecular response to nanomaterial particulates.

The varied transcriptomic response to nanoparticles has hampered the understanding of the mechanism of action. Here, by performing a meta-analysis of a large collection of transcriptomics data from various engineered nanoparticle exposure studies, we identify common patterns of gene regulation that impact the transcriptomic response. Analysis identifies deregulation of immune functions as a prominent response across different exposure studies. Looking at the promoter regions of these genes, a set of binding sites for zinc finger transcription factors C2H2, involved in cell stress responses, protein misfolding and chromatin remodelling and immunomodulation, is identified. The model can be used to explain the outcomes of mechanism of action and is observed across a range of species indicating this is a conserved part of the innate immune system.

Superstatistical Energy Distributions of an Ion in an Ultracold Buffer Gas.

An ion in a radio frequency ion trap interacting with a buffer gas of ultracold neutral atoms is a driven dynamical system which has been found to develop a nonthermal energy distribution with a power law tail. The exact analytical form of this distribution is unknown, but has often been represented empirically by q-exponential (Tsallis) functions. Based on the concepts of superstatistics, we introduce a framework for the statistical mechanics of an ion trapped in an rf field subject to collisions with a buffer gas. We derive analytic ion secular energy distributions from first principles both neglecting and including the effects of the thermal energy of the buffer gas. For a buffer gas with a finite temperature, we prove that Tsallis statistics emerges from the combination of a constant heating term and multiplicative energy fluctuations. We show that the resulting distributions essentially depend on experimentally controllable parameters paving the way for an accurate control of the statistical properties of ion-atom hybrid systems.

Risk factors for isolated talipes equinovarus in Western Australia, 1980-1994.

A case-control study based on routinely collected data for a West Australian (WA) cohort of births born 1980-94 inclusive was used to identify potential risk factors for the foot deformity isolated talipes equinovarus. Race and sex were identified as risk factors and risk modifiers of the condition in WA infants. In comparison with their female counterparts, Aboriginal males were at greater risk of the deformity than Caucasian males (odd ratio [OR] 7.15, 95% confidence interval [CI] 2.68, 21.12 vs. OR 1.63, 95% CI 1.24, 2.15 respectively). Sex-specific risk estimates of the deformity showed that Aboriginal males were at more than four times the risk of Caucasian males (OR 4.27, 95% CI 2.30, 8.25 respectively), but the risk amongst Aboriginal females was not dissimilar to the risk amongst Caucasian females (OR 1.12, 95% CI 0.49, 2.45). Intrauterine constraint of the fetus was not found to be an important contributing factor to the deformity after accounting for the effect of all risk factors modelled in multivariable analyses. Indicators of intrauterine constraint including prolonged gestation, high infant birthweight, young maternal age (< 20 years) and breech presentation were not associated with excess numbers of isolated talipes equinovarus cases. Limited numbers of cases associated with other indicators of intrauterine constraint, including the specific categories of short maternal stature and a twin pregnancy prevented definitive conclusions regarding their association with the deformity. Improved data quality for gestational age estimates and oligohydramnios status are required before determining the prenatal risk impact of season of conception and of reduced amniotic fluid levels, respectively, on the occurrence of the deformity.

Changes in Expanded Program for Immunization coverage for mother and child in Krakor, Cambodia 1996--1998.

We evaluated a training intervention aimed at enhancing the roles of health centre staff, Village Health Volunteers (VHVs) and Traditional Birth Attendants (TBAs) within the Expanded Program for Immunization (EPI) in the district of Krakor, Cambodia. We conducted population-based surveys to determine the coverage of the EPI at baseline (1996) and after the intervention (1998), using data from health cards for mothers and their children and history data. Statistically significant changes over the 2-year period were apparent for tetanus, BCG, polio and DTP, supporting the positive impact the training intervention had on immunization coverage in the district.

Changes in ante-natal care and family planning in Krakor, Pursat, Cambodia, 1996-1998.

This study examines variations in ante-natal care (ANC) and family planning in Krakor, Pursat, Cambodia between 1996 and 1998. Population-based survey interviews were conducted with a total of 291 women in 1996 and 211 women in 1998. An intervention strategy designed to enhance the skills and roles of Health Centre staff, Village Health Volunteers (VHVs) and Traditional Birth Attendants (TBAs) was conducted. Over this timeframe, reported ANC access increased from 37% to 47%. Most women delivered their last child at home, usually assisted by a TBA. Few women practiced family planning, despite the fact that most reported that they did not want any further children. A range of reasons for not practicing family planning were found to be highly significant, including the lack of available services (p<0.01). The fear of side-effects decreased significantly (p<0.01), with the community education provided by the VHVs and TBAs, potentially being one contributing factor. The results of this study suggest that continual support of VHVs and TBAs will further improve the health of women in Cambodia.

Population-based outcomes after 28,246 in-hospital vasectomies and 1,902 vasovasostomies in Western Australia.

OBJECTIVES: To examine trends in vasectomy and vasovasostomy, and the surgical complications and factors associated with reversal after vasectomy, and paternity after vasovasostomy. PATIENTS AND METHODS: Procedure rates were estimated from 1980 to 1996 in the population of Western Australia. Linked hospital morbidity records were used in the follow-up of men after vasectomy to estimate the risks of complications and reversals. Records of vasovasostomies were linked to the paternity field on birth registrations. Independent effects of the study factors were examined using Cox regression. RESULTS: There was little net change in vasectomy rates, whereas vasovasostomy rates increased in men aged 30-49 years. Risks of surgical complications were low and decreased for vasovasostomy. At 12-15 years after vasectomy, the risk of reversal levelled at 2. 4% in the total cohort and at 11.1% in men aged 20-24 years. The risk of vasovasostomy was 69% greater after vasectomy performed in 1994-96 than in 1980-84 (P = 0.011). The factors strongly associated with reversal were age < 30 years and being single, divorced or separated at the time of vasectomy. Paternity was achieved after an estimated 53% of vasovasostomies. Successful reversal was more likely if the man was younger at vasectomy and the time elapsed was comparatively short. Compared with vasovasostomies performed in 1980-84, the success rate of those in 1994-96 was almost four times higher. CONCLUSION: Population rates of vasectomy are stable but the risk of seeking a reversal has increased. Outcomes after vasovasostomy have improved. Care should be taken during the counselling of men before vasectomy, and especially in those aged <30 years.

Population-based linkage of health records in Western Australia: development of a health services research linked database.

OBJECTIVES: To introduce the Western Australian Health Services Research Linked Database as infrastructure to support aetiologic, utilisation and outcomes research. To compare the study population, data resources, technical systems and organisational supports with international best practice in record linkage and health research. METHOD AND RESULTS: The WA Linked Database systematically links the available administrative health data within an Australian State of 1.7 million people. It brings together, initially, six core data elements (birth records, midwives' notifications, cancer registrations, in-patient hospital morbidity, in-patient and public out-patient mental health services data and death records). It will be updated regularly and is designed, in future extensions, to include data on primary, residential and domiciliary care and health surveys. Linkage uses probabilistic matching of patient names and other identifiers. Geocodes for spatial analysis are assigned using address linkage and mapping software. By June 1997, the project had taken 2 1/2 years to develop the system and link seven million core data records from 1980 to 1995. CONCLUSIONS: The system is consistent with international benchmarks, from four centres of excellence, for the study population, core datasets, matching and geocoding, and collaborative networks. There are prospects to redress deficiencies in primary medical contact and other data resources, validation studies, tracing systems and a more supportive legal framework. IMPLICATIONS: The WA Linked Database will be used in combination with medical record audits to provide a comprehensive evaluation of health system performance.

Validation of linked administrative data on end-stage renal failure: application of record linkage to a 'clinical base population'.

OBJECTIVE: To evaluate the use of record linkage to monitor the occurrence of end-stage renal failure in Western Australia in 1980-94. METHODS: A clinical base population of 1,046 patients was identified from the Western Australian (WA) Health Services Research Linked Database. To exclude acute renal failure, patients were selected if they received in-hospital renal dialysis on more than 10 occasions over more than 28 days in 1980-94. Estimates of annual incident and prevalent cases were validated against the ANZDATA dialysis and transplant register. Reasons for discrepancy were investigated by an ad hoc linkage between the two data sources. RESULTS: The WA Linked Database counted slightly fewer incident cases (-7%) and slightly more prevalent cases (+7%) than the ANZDATA Register. The Linked Database identified 97% of cases on the ANZDATA Register, but this fell to 83% post case definition, probably due to patients receiving home-based dialysis failing to meet our case definition. ANZDATA correctly identified 90% of cases in the linked file. CONCLUSION: Trends in end-stage renal failure from 1986 to 1994, based on the Linked Database, were the same as those reported from purpose-designed disease registers. IMPLICATIONS: Linked administrative data provide a valid and efficient means to plan and evaluate many of the routine aspects of renal dialysis and transplant services.

Trends in repeat prostatectomy after surgery for benign prostate disease: application of record linkage to healthcare outcomes.

OBJECTIVE: To compare the risk of repeat prostatectomy for benign prostatic hyperplasia (BPH) in a population-based cohort of 19 598 men in Western Australia treated by transurethral resection of the prostate (TURP) or open prostatectomy over a 16-year period. PATIENTS AND METHODS: The Western Australian Health Services Research Linked Database was used to extract all hospital morbidity data, death records and prostate cancer registrations for men who had prostate surgery for BPH in 1980-95. The cumulative incidence of first repeat prostatectomy calculated using the actuarial life-table and incidence-rate ratios of the first repeat prostatectomy, comparing TURP and open prostatectomy, were obtained using Cox regression. RESULTS: The cases comprised 18 464 TURPs and 1134 open prostatectomies, from which there were 1095 subsequent repeat prostatectomies. After adjustment for calendar time, age and admission type, the incidence rate of the first repeat prostatectomy was up to 2.30 times higher (95% confidence interval, 1.62-3.27) after initial TURP than for initial open prostatectomy. The absolute risks at 8 years for TURP was 6.6%, and was 3.3% for open prostatectomy. CONCLUSION: The absolute risk of a repeat prostatectomy for TURP and open prostatectomy were consistent with the best reported international experience. There was evidence that the risk in 1990-95 had declined compared with earlier periods, despite a shift towards more closed procedures. The differential risks of repeat prostatectomy should be explained to patients and considered in the development of clinical guidelines, notwithstanding the advantages of TURP over open prostatectomy in terms of surgical morbidity and cost.

Mortality and prostate cancer risk in 19,598 men after surgery for benign prostatic hyperplasia.

OBJECTIVES: To examine postoperative mortality and prostate cancer risk after the first prostatectomy for benign prostatic hypertrophy over a 17-year period in a population-based cohort of men in Western Australia, using improved methods to adjust for comorbidity. PATIENTS AND METHODS: The relative survival from death and prostate cancer incidence was calculated against the background population rates. The outcomes of transurethral resection of the prostate (TURP) and open prostatectomy (OP) were compared adjusting for calendar year, age, admission type and comorbidity using Cox regression. Fractional polynomials were used to take account of nonlinearity in confounder effects. RESULTS: At 10 years, the relative survival was 116.5% in TURP patients and 123.5% after OP. Adjusting only for confounding by age, calendar year and admission type, TURP had a higher mortality rate than OP (rate ratio, RR, 1. 20; 95% confidence interval 1.08-1.34). The RR fell to 1.10 (0.99-1. 23) after adjustment for comorbidity and to 1.07 (0.95-1.19) when accounting for nonlinearity. The relative survival from the incidence of prostate cancer at 10 years was 103.7% after TURP and 104.5% after OP. The RR adjusted for age and calendar year was 1.44 (0.94-2.21) for incidence and 1.37 (0.81-2.29) for prostate cancer mortality. CONCLUSION: There is at most a small and clinically unimportant excess mortality risk from TURP; any difference could be due to a protective effect of OP on the long-term risk of prostate cancer and a lower rate of repeat prostatectomy.

The Sports Challenge international programme for identified 'at risk' children and adolescents: a Singapore study.

The current world wide phenomena of youth suicide which became a major issue for countries in the early nineties, is still growing exponentially. The Sports Challenge program was initiated in 1992 in Western Australia to identify 'at risk' children and adolescents who display: a low sense of basic trust, a sense of shame and doubt, a sense of inferiority and a sense of identity confusion with common characteristics of low self esteem. The subsequent program is based on a strong statistical paradigm encompassing current and historical information with reliable and objective evaluation measures. To this end, since 1992, Sports Challenge has been recognised as a 'World Best Practice' in redressing the issue of 'at risk' children and adolescents. The program now operates in over 150 schools and communities throughout Australia and 24 schools and Detention Centres in Singapore. This paper will allow a window into the development of the program and the successful transfer of the project into Singapore. The Singapore study which began in 1996 has revealed the success of the Sports Challenge program cross culturally with improvement in self esteem and self concept of 'at risk' groups in the range of 18% to 44%.

Prostate cancer in Western Australia: trends in incidence and mortality from 1985 to 1996.

OBJECTIVE: To measure trends in recorded incidence and mortality rates of prostate cancer in Western Australia from 1985 to 1996 and to relate these to prostate-specific antigen (PSA) testing for prostate cancer. DESIGN: Descriptive study based on data from the Western Australian Cancer Registry, the Australian Bureau of Statistics and the Health Insurance Commission. DATA: All newly diagnosed cases of prostate cancer and all deaths from prostate cancer in Western Australia from 1985 to 1996. MAIN OUTCOME MEASURES: Recorded incidences and mortality rates for prostate cancer. RESULTS: After increasing steadily from 42 per 100,000 person-years in 1985 to 61 in 1992, the recorded incidence more than doubled to 134 per 100,000 person-years in 1994, then fell sharply to 87 in 1996. Among men aged 50 years or more, those aged 50-54 years had the largest annual increases: 14% (95% confidence interval [CI], 10%-19%) from 1985 to 1992 and 108% (95% CI, 84%-134%) from 1992 to 1994. They also had the smallest annual decline between 1994 and 1996 (8%; 95% CI, 1% increase to 16% decrease). The mortality rate showed no sudden increases or decreases. In men aged 60 years or older, the mortality rate increased annually by 2.9% (95% CI, 2%-4%) from 1985 to 1996. The number of Medicare reimbursements for PSA tests increased until May 1995, then fell. There was a significant correlation between the monthly number of PSA tests and new cases of prostate cancer (P < 0.01). CONCLUSIONS: Following a period of steady increase, the recorded incidence of prostate cancer increased dramatically in 1992 because of screening by PSA testing. From 1994, these incidence figures declined almost as sharply, partly because of reductions in testing. The mortality rate has not shown any systematic deviation from its long-term trend.

The Quality of Surgical Care Project: a model to evaluate surgical outcomes in Western Australia using population-based record linkage.

BACKGROUND: The aim of this study is to establish a model to evaluate surgical outcomes and, where indicated, recommend changes to improve the quality of surgical care in Western Australia (WA). Open resection for aneurysm of the abdominal aorta was the first procedure evaluated and the results are reported in an accompanying paper. METHODS: The Quality of Surgical Care Project (QSCP) is conducted under the aegis of the Royal Australasian College of Surgeons (RACS) in WA, and brings together a multidisciplinary team of surgeons, public health researchers and health service administrators. The Western Australia Health Services Research Linked Database (the WA Linked Database) is used to provide linked chains of patients records residing in the state health department from the following sources: hospital morbidity data system, birth and death records, mental health services data, cancer registrations and midwives' notifications. This links 16 years of population-based patient records from 1980, including all public and private hospital admissions and re-admissions. The Quality of Surgical Care Project was established to use and to correlate the data from the WA Linked Database. RESULTS: The result is a powerful database for a contained population that is available for scientific analysis by a multidisciplinary team of clinical epidemiologists, surgeons and health service managers. Users will have the ability to establish benchmark standards for the outcomes of surgical procedures in WA for use in quality improvement programmes run by the College and will facilitate self-directed performance auditing activities as a commitment to greater community accountability. CONCLUSIONS: The Quality of Surgical Care Project provides a potential model of benefits to be realized by both the medical profession and the community through multidisciplinary collaboration supported by adequate information. Although migration from WA is relatively low, future linkage to the state electoral roll will allow correction for any population change.

Hospitalisation of the elderly during the last year of life: an application of record linkage in Western Australia 1985-1994.

STUDY OBJECTIVE: To measure the trend, pattern, and cost of time spent in hospital during the last year of life in Western Australia and to identify trends in the place of death. The results were compared with those reported from the Oxford Record Linkage Study. DESIGN: Mortality records for those aged 65 years and over were linked to inpatient hospital morbidity records with a date of separation within one year before death. Comparative inpatient resource utilisation was estimated using ANDRG 3.0 cost weights for Australian public hospitals. SETTING: Western Australia. PARTICIPANTS: All 68,875 persons aged 65 years and over who died between 1 January 1985 and 31 December 1994. MAIN RESULTS: Increasing proportions of all age groups (65-74, 75-84, and 85+ years) were admitted to hospital at least once in the year before death during 1985-94, but the chance of admission decreased with age. There was a trend towards a greater number of shorter admissions per person. Total bed days per person showed no significant increase, except at ages 65-74 years. Total inpatient resource utilisation during the last year of life was lowest and remained constant in those aged 85 years and over, while increasing gradually (3.7% per annum) in the younger elderly. The Western Australian population spent more time in hospital in the last year of life at ages 65-74 years, but the advanced elderly spent less time in hospital, when compared with the Oxford Region. CONCLUSIONS: Recent gains in life expectancy and higher per capita health expenditure have not been accompanied by more time spent in hospital during the last year of life at ages 75+ years. International differences between Western Australia and Oxford can be explained by differences in aged care provision.

Intermittent auscultation for the intrapartum assessment of fetal well-being in Western Australia.

In May 1995, in response to a decision of the Perinatal and Infant Mortality Committee of Western Australia, a survey of Western Australian hospitals was performed to ascertain what policies were in use for the monitoring of the fetal heart rate in labour and what proportion of these hospitals had access to electronic monitoring by cardiotocography. A response was received from 96% of the surveyed hospitals. More than half the births in this State (13,950 of 25,238) were monitored in labour using intermittent auscultation as the primary test; 7.5% of Western Australian births each year occurred in hospitals in which electronic monitoring was not available. Fewer than 50% of hospitals had written protocols describing the method of auscultation of the fetal heart during labour, the indications to contact a doctor or the management of fetal distress. The protocols which did exist displayed considerable variation in the recommended frequency of intermittent auscultation. The lack of standard practice in this field probably results from uncertainties in the literature. Intermittent auscultation has not been subjected to rigorous scientific evaluation as a screening tool and guidelines documenting ideal auscultatory practices need to balance the precision of electronic monitoring and freedom from intervention. Based on this compromise and existing evidence, a protocol for intermittent auscultation in normal labour is proposed.

Primary mental health care in a rural community: patient and illness profiles, treatment and referral.

The objective of this study was to determine the extent and nature of psychosocial morbidity and patterns of treatment and referral in rural general practice in a West Australian community. The research design was a survey based on structured questionnaires completed by the general practitioners about patients consulting with mental health problems in Bunbury in the rural south west region of Western Australia. Twenty-two general practitioners from five surgeries collected information on 428 patients, pertaining to socio-demographic characteristics, reasons for encounter, diagnoses, social problems, chronicity, counselling, medication and use of referral services. The positive stereotype of patients (i.e. most likely to be identified) consisted of a female preponderance in a ratio of 3:1, a high prevalence in the middle years (35-54), an overrepresentation of the divorced and separated, unemployed men and housewives. Neurosis was the most prevalent diagnosis at 68.5%, chronicity at 55%, and the most frequent social problems reported to the GPs related to relationship difficulties with partner, and being physically ill. Only a quarter of the patients were referred to other counselling services and social problems were an important reason for referral. Particular attention needs to be given to the negative stereotype in general practice of young people under the age of 25. With the bulk of psychosocial disorder concentrated in general practice, with the evident association of mental illness with physical illness and social problems, and with the lack of specialist resources in rural areas, innovative ways of support from other mental health professionals need to be addressed.

Viral meningitis due to echovirus types 6 and 9: epidemiological data from Western Australia.

During the autumn of 1992, Western Australia experienced a large viral meningitis outbreak of dual aetiology. Of the 161 cases, 64% were children under 15 years of age, with the highest notification rate being in children less than 5 years of age. Echovirus 9 caused 41% of cases and occurred mainly in the metropolitan areas of Western Australia whereas echovirus 6, which caused 37% of cases, was more widespread. An enterovirus was cultured from 70% of CSF specimens, 88% of faecal specimens and 68% of upper respiratory tract specimens. High CSF white cell counts and neutrophil predominance were common. Seven cases had normal CSF white cell counts even though an enterovirus was isolated from the CSF. Therefore, the CSF findings were of restricted value in excluding viral meningitis, and did not reliably distinguish between bacterial and viral meningitis.

Changing epidemiology of methicillin-resistant Staphylococcus aureus in Western Australia.

OBJECTIVE: To assess the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) in Western Australia. DESIGN: Retrospective review of statutory notification data. SETTING: Western Australia (WA), 1993. OUTCOME MEASURES: Notification rates, antibiotic resistance patterns and classification of isolates as imported or WA MRSA strains on the basis of antibiotic susceptibility. RESULTS: There were 204 notifications of MRSA, 78% of which were classified as WA MRSA. Three outbreaks of MRSA infection and colonisation occurred in separate WA hospitals. Notification rates per 100,000 were highest in the rural regions: the Kimberley (86.32), Goldfields (62.47), Mid West (37.21) and Pilbara (27.38) regions; and lowest in the metropolitan regions (5.52). All MRSA isolates were susceptible to vancomycin. Most imported strains were susceptible to amikacin, bacitracin, chloramphenicol, framycetin, fusidic acid and novobiocin, but only 23% to gentamicin. WA MRSA strains remained predominantly susceptible to all antibiotics tested, except beta-lactams, erythromycin and tetracycline, but a few strains resistant to rifampicin (1%) and fusidic acid (3%) appeared in the second half of 1993. CONCLUSIONS: The epidemiology of MRSA in WA is changing rapidly, with increases in both the numbers of notifications and the proportion from country regions. A new strain of MRSA (WA MRSA) that is less resistant to antibiotics than imported MRSA has emerged and is threatening the State's success in preventing establishment of MRSA in its hospitals.

A controlled trial of nurse counselling on lifestyle change for hypertensives treated in general practice: preliminary results.

1. We assessed whether a lifestyle modification programme implemented by nurse counsellors in a general practice setting would improve blood pressure (BP) control in treated hypertensive patients. 2. Patients were randomized into a control group or one of two intervention groups who received either a high or low level of counselling. 3. Patients in the intervention groups had appointments every 4th week for 18 weeks. The low intervention group had one practice appointment and five telephone counselling appointments while the high intervention group had six appointments in their general practice. The patients were counselled using a stage of change behavioural model and motivational interviewing to: reduce alcohol consumption, dietary fat and salt intake and weight; cease smoking; and increase leisure time physical activity. 4. Compared with controls the low intervention group showed significant decreases in alcohol and salt intake while the high intervention resulted in significant decreases in both weight and BP. 5. We conclude that nurse counselling targeted to specific aspects of lifestyle can improve BP control and weight in treated hypertensive patients over 18 weeks. Its longer term effectiveness in the management of hypertension warrants further evaluation.

Acute symptoms and sequelae of Ross River virus infection in South-Western Australia: a follow-up study.

BACKGROUND: Unusually high tides along the south-west coast of Western Australia (WA) during the spring and summer of 1988-89 provided ideal breeding conditions for mosquito vectors of Ross River virus (RRV). This was followed by the biggest outbreak of RRV infection ever documented in WA (330 notified cases). OBJECTIVES: To describe the nature and duration of symptoms of RRV infection in WA, and associated functional disability; to determine the perceived effectiveness of treatments; to determine the usefulness of available information on RRV infection. STUDY DESIGN: A retrospective study of all cases of RRV infection reported from South West WA during the 1988-89 outbreak, using a self-administered patient questionnaire. RESULTS: The most common symptoms were arthralgia, tiredness and lethargy, and joint stiffness and swelling. In patients with joint manifestations, the knees, wrists and ankles were almost always affected. Non-steroidal anti-inflammatory agents, rest, simple analgesics and hydrotherapy were subjectively the most helpful treatments. Only 27% of patients had recovered completely within 6 months of onset of symptoms. Three years after the outbreak, up to 57% still experienced at least intermittent joint symptoms. Less than one-third of people reported that the available information adequately explained the consequences of RRV infection. CONCLUSIONS: Compared with patients elsewhere in Australia, people infected with RRV in the South West of WA experience a slightly different spectrum of clinical symptoms, with a longer period of disability. This may be related to the presence of a different topotype of the virus to that found elsewhere in Australia. Better information for doctors and patients on the likely course of the illness is needed. Future studies should examine the economic cost associated with RRV infection, and evaluate treatments to shorten the period of disability.