Half Of Failures Research Articles

Reliability of dump trucks in placer mining in permafrost zone

This study analyzes failures of dump trucks in open pit mines depending on the season and dump truck service life during placer mining in the permafrost zone. It i s found that more than half of failures are the faults of suspension, engine and drive axle. It is determined that the number of failures of dump trucks increases in the warm season (May–Sep tember) and with extension of service life of dump trucks more than by 1.5–2.0 times. The yearly increase in the number of failures is due to the deterioration of road conditions in the warm season. Melting p ermafrost causes an almost semiliquid mixture of water and various types of soil and sand in the work zone. The load-bearing capacity of soilwo rsens. The wheels of moving dump trucks make deeper track on th e road surface. This results in the increased loads imposed on the components and assemblies of the chassis, transmission and hydraulic system. The chassis components and parts, which have no closed (isolated) lubrication system, are subje cted to abrasive wear because of dirt getting into them. The data on the dump truck failures per the components and aggregates, as well as on the number of failures subject to the season and dump truck service life are obtained. Th e implemented studies into reliability of dump trucks in placer mining in the permafrost zone allow recommending balancing the seasonal variation in the number of failures by production scheduling with regard to the 75 % increase in the maintenance efforts in the warm season. For achieving efficiency and rhythmicity of placer mining operations in the warm season, it is necessary to take into account deterioration of road conditions, which affects the working capacity of dump trucks.

Virological Outcomes of Second-line Protease Inhibitor-Based Treatment for Human Immunodeficiency Virus Type 1 in a High-Prevalence Rural South African Setting: A Competing-Risks Prospective Cohort Analysis.

Second-line antiretroviral therapy (ART) based on ritonavir-boosted protease inhibitors (bPIs) represents the only available option after first-line failure for the majority of individuals living with human immunodeficiency virus (HIV) worldwide. Maximizing their effectiveness is imperative. This cohort study was nested within the French National Agency for AIDS and Viral Hepatitis Research (ANRS) 12249 Treatment as Prevention (TasP) cluster-randomized trial in rural KwaZulu-Natal, South Africa. We prospectively investigated risk factors for virological failure (VF) of bPI-based ART in the combined study arms. VF was defined by a plasma viral load >1000 copies/mL ≥6 months after initiating bPI-based ART. Cumulative incidence of VF was estimated and competing risk regression was used to derive the subdistribution hazard ratio (SHR) of the associations between VF and patient clinical and demographic factors, taking into account death and loss to follow-up. One hundred one participants contributed 178.7 person-years of follow-up. Sixty-five percent were female; the median age was 37.4 years. Second-line ART regimens were based on ritonavir-boosted lopinavir, combined with zidovudine or tenofovir plus lamivudine or emtricitabine. The incidence of VF on second-line ART was 12.9 per 100 person-years (n = 23), and prevalence of VF at censoring was 17.8%. Thirteen of these 23 (56.5%) virologic failures resuppressed after a median of 8.0 months (interquartile range, 2.8-16.8 months) in this setting where viral load monitoring was available. Tuberculosis treatment was associated with VF (SHR, 11.50 [95% confidence interval, 3.92-33.74]; P < .001). Second-line VF was frequent in this setting. Resuppression occurred in more than half of failures, highlighting the value of viral load monitoring of second-line ART. Tuberculosis was associated with VF; therefore, novel approaches to optimize the effectiveness of PI-based ART in high-tuberculosis-burden settings are needed. NCT01509508.

Failure After Laparoscopic Pyeloplasty: Prevention and Management

Because of the high success of laparoscopic pyeloplasty (LP) for ureteropelvic junction obstruction, strategies for managing failures are less well described. We report our experience with persistent or recurrent obstruction after LP. We reviewed 128 patients who were treated with LP at our institution from 1996 through 2008. Success was defined as objective resolution of obstruction by renal scintigraphy, Whitaker testing, or direct visualization. We extracted data by chart review regarding patient demographics, medical history, operative technique, and salvage treatments. We then assessed for association between patient characteristics and treatment failure. Overall, 102 patients had sufficient follow-up, of which 84 (82%) were successes. Of 18 failures, median time to failure was 2.5 months (0.5-88 mos). Of 10 failures managed endoscopically, 7 were salvaged. One of two patients treated conservatively ultimately had resolution while six patients needed simple nephrectomy. Overall, 8 (44%) were salvageable with median follow-up of 19 months (4-58 mos). Patients with failure were more likely to have diabetes mellitus, longer length of stay, higher American Society of Anesthesiologists (ASA) score, a stent placed at the time of pyeloplasty, or ureteral stent malfunction (P<0.05). Patients with failure despite salvage were more likely to have stent malfunction or body mass index >30 kg/m(2) (P<0.05). Adjusting for the above factors, stent placement at time of surgery and ASA score >2 were associated with failure (P<0.05) while periureteral fibrosis trended toward a significant association (P=0.061). Nearly half of failures after LP are salvageable, many with endoscopic management.

Bone cements as adjuvant techniques for ossicular chain reconstruction.

The osseointegrative capacity of medical-grade bone cement can be used to improve fixation and prevent displacement of an ossicular prosthesis in a guinea pig model. Successful ossiculoplasty requires a firm connection between the vibrating tympanic membrane and the inner ear. In patients requiring revision ossiculoplasty, half of failures are due to prosthesis displacement. Bone cements have been used as prosthetic material in craniofacial surgery, and their adhesive and osseointegrative properties make them ideal for use in ossicular reconstruction. Twenty-four adult male guinea pigs underwent a postauricular surgical approach for access to the middle ear. Hydroxyapatite and Dahllite cements were used in an alternating fashion to fix ossicular bone. Four animals were killed immediately to demonstrate mechanical bonding of the ossicles at the time of application. Nineteen animals were killed 8 weeks postoperatively to assess bonding capacity and histologic inflammation. Both cements mechanically bonded the ossicles at the time of application, but Dahllite cement set faster in the moist environment of the middle ear space. Histologic examination showed bonding of the ossicles with both cements, with little evidence of inflammation or foreign body reaction. Hydroxyapatite and Dahllite bone cements showed evidence of osseointegration with ossicular bone in the guinea pig model. Further studies are under way to determine the osseointegrative capacity of Dahllite cement between the guinea pig malleus and a partial prosthesis, and any ototoxic effects with use in the middle ear.

Safety, efficacy, and acceptability of medical abortion in China, Cuba, and India: A comparative trial of mifepristone-misoprostol versus surgical abortion

OBJECTIVE: We investigated safety, efficacy, and acceptability of an oral regimen of medical abortion compared with surgical abortion in three developing countries. STUDY DESIGN: Women ( n = 1373) with amenorrhea ≤56 days chose either surgical abortion (as provided routinely) or 600 mg of mifepristone followed after 48 hours by 400 μg of misoprostol. This is the appropriate design for studying safety, efficacy, and acceptability among women selecting medical abortion over available surgical services. RESULTS: The medical regimen had more side effects, particularly bleeding, than did surgical abortion but very few serious side effects. Failure rates for medical abortion, although low, exceeded those for surgical abortion: 8.6% versus 0.4% (China), 16.0% versus 4.0% (Cuba), and 5.2% versus 0% (India). Nearly half of failures among medical clients were not true drug failures, however, but surgical interventions not medically necessary (acceptability failures or misdiagnoses). Women were satisfied with either method, but more preferred medical abortion. CONCLUSION: Medical abortion can be safe, efficacious, and acceptable in developing countries.(Am J Obstet Gynecol 1997;176:431-7.)