A revised position for the primary strand of the Pleistocene-Holocene San Andreas fault in southern California.

The San Andreas fault has the highest calculated time-dependent probability for large-magnitude earthquakes in southern California. However, where the fault is multistranded east of the Los Angeles metropolitan area, it has been uncertain which strand has the fastest slip rate and, therefore, which has the highest probability of a destructive earthquake. Reconstruction of offset Pleistocene-Holocene landforms dated using the uranium-thorium soil carbonate and beryllium-10 surface exposure techniques indicates slip rates of 24.1 ± 3 millimeter per year for the San Andreas fault, with 21.6 ± 2 and 2.5 ± 1 millimeters per year for the Mission Creek and Banning strands, respectively. These data establish the Mission Creek strand as the primary fault bounding the Pacific and North American plates at this latitude and imply that 6 to 9 meters of elastic strain has accumulated along the fault since the most recent surface-rupturing earthquake, highlighting the potential for large earthquakes along this strand.

A simple cost-effective method of microsurgical simulation training: the turkey wing model.

The rat femoral artery (RFA) anastomosis model has been the gold standard in microsurgical simulation training. While effective, live animal use requires animal use committee regulation and costly maintenance. Our institution's animal laboratory is remote to the hospital, limiting access by our busy surgical residents with their limited duty hours. We present an alternative convenient, cost-effective model. Ten frozen turkey wings were divided into distal and proximal segments. Vessel diameter, length, and anastomosis perfusion were assessed. Proximal brachial arteries ("humeral" segments) measured 8.85 ± 1.14 cm long with diameter 1.69 ± 0.27 mm. Distal brachial arteries ("forearm") measured 10.5 ± 2.06 cm long with diameter 1.25 ± 0.25 mm. An 8-lb box (~20 wings) cost $13.76. Separate use of the segments provides two training sessions with $0.35 per session effective cost. Our average cost for RFA microsurgical training sessions was $120 dollars for a single rat 2-hour session and $66 per rat if a maximum crate load of six rats was used. Besides significant cost, not all training programs are equipped to house, care for, and use rats in microsurgical training. We now use turkey wings for microvascular training. They are cheap, abundant, readily accessible for training, and consistent with tissue quality and vessel size approximating human systems.

Total patellar skin loss from cryotherapy after total knee arthroplasty.

The use of cryotherapy after total knee arthroplasty is a very common therapeutic adjunct accepted as routine postoperative care. We present 2 cases of total patellar skin loss due to cryotherapy after total knee arthroplasty. Substantial soft tissue defects were created after the initial debridement of the necrotic tissue. Both patients were evaluated for frostbite, and the wounds were sharply debrided. Application of an advanced wound management technique involves the use of a collagen-glycosaminoglycan biodegradable bilayer matrix, silver impregnated antimicrobial dressing, and low-pressure vacuum device, followed by delayed split thickness skin grafting and low-pressure vacuum device. We find that this technique provided durable soft tissue coverage for necrotic wounds of the knee that do not involve the joint capsule.

Talc-bearing serpentinite and the creeping section of the San Andreas fault.

The section of the San Andreas fault located between Cholame Valley and San Juan Bautista in central California creeps at a rate as high as 28 mm yr(-1) (ref. 1), and it is also the segment that yields the best evidence for being a weak fault embedded in a strong crust. Serpentinized ultramafic rocks have been associated with creeping faults in central and northern California, and serpentinite is commonly invoked as the cause of the creep and the low strength of this section of the San Andreas fault. However, the frictional strengths of serpentine minerals are too high to satisfy the limitations on fault strength, and these minerals also have the potential for unstable slip under some conditions. Here we report the discovery of talc in cuttings of serpentinite collected from the probable active trace of the San Andreas fault that was intersected during drilling of the San Andreas Fault Observatory at Depth (SAFOD) main hole in 2005. We infer that the talc is forming as a result of the reaction of serpentine minerals with silica-saturated hydrothermal fluids that migrate up the fault zone, and the talc commonly occurs in sheared serpentinite. This discovery is significant, as the frictional strength of talc at elevated temperatures is sufficiently low to meet the constraints on the shear strength of the fault, and its inherently stable sliding behaviour is consistent with fault creep. Talc may therefore provide the connection between serpentinite and creep in the San Andreas fault, if shear at depth can become localized along a talc-rich principal-slip surface within serpentinite entrained in the fault zone.

Primary care use of antipsychotic drugs: an audit and intervention study.

BACKGROUND: Concerns regarding the use of antipsychotic medication in secondary care suggested an examination of primary care prescribing. AIM: To audit and intervene in the suboptimal prescribing of antipsychotic drugs to primary care patients. DESIGN OF STUDY: Cross-sectional prevalence: subsequent open treatment intervention. SETTING: Seven of the 29 practices in the Eastern Hull Primary Care Trust. METHODS: Criteria for best practice were developed, against which prescribing standards were tested via audit. Patients identified as suboptimally prescribed for were invited to attend an expert review for intervention. RESULTS: 1 in 100 of 53,000 patients was prescribed antipsychotic treatment. Diagnoses indicating this were impossible to ascertain reliably. Half the regimes failed one or more audit criteria, leaving diagnosis aside. Few practices agreed to patients being approached: of 179 invitations sent, only 40 patients attended. Of 32 still taking an antipsychotic drug, 26 required changes. Mean audit criteria failed were 3.4, lack of psychotic disorder diagnosis and problematic side effects being most frequent. Changes were fully implemented in only 16 patients: reasons for complete or partial failure to implement recommendations included the wishes or inaction of patients and professionals, and worsening of symptoms including two cases of antipsychotic withdrawal syndrome. CONCLUSION: Primary care prescribing of antipsychotic drugs is infrequent, but most is unsatisfactory. Intervention is hampered by pluralistic reluctance: even with expert guidance, rationalisation is not without risk. Use of antipsychotic drugs in primary care patients whose diagnosis does not warrant this should be avoided. HOW THIS FITS IN: This study adds to concerns regarding high levels of off-licence use of potentially harmful medication. It adds evidence of major difficulties in rationalizing suboptimal regimes despite expert input. Relevance to the clinician is that it is better to avoid such regimes in the first place especially if there is no clear 'exit strategy': if in doubt, seek a specialist opinion.