Z-2 Threaded Insert Design and Testing

NASA's Z-2 prototype space suit contains several components fabricated from an advanced hybrid composite laminate consisting of IM10 carbon fiber and fiber glass. One requirement was to have removable, replaceable helicoil inserts to which other suit components would be fastened. An approach utilizing bonded in inserts with helicoils inside of them was implemented. During initial assembly, cracking sounds were heard followed by the lifting of one of the blind inserts out of its hole when the screws were torqued. A failure investigation was initiated to understand the mechanism of the failure. Ultimately, it was determined that the pre-tension caused by torqueing the fasteners is a much larger force than induced from the pressure loads of the suit which was not considered in the insert design. Bolt tension is determined by dividing the torque on the screw by a k value multiplied by the thread diameter of the bolt. The k value is a factor that accounts for friction in the system. A common value used for k for a non-lubricated screw is 0.2. The k value can go down by as much as 0.1 if the screw is lubricated which means for the same torque, a much larger tension could be placed on the bolt and insert. This paper summarizes the failure investigation that was performed to identify the root cause of the suit failure and details how the insert design was modified to resist a higher pull out tension

Adolescence and the next generation.

Adolescent growth and social development shape the early development of offspring from preconception through to the post-partum period through distinct processes in males and females. At a time of great change in the forces shaping adolescence, including the timing of parenthood, investments in today's adolescents, the largest cohort in human history, will yield great dividends for future generations

The mediation of social influences on smoking cessation and awareness of the early signs of lung cancer

Background Whilst there has been no clear consensus on the potential for earlier diagnosis of lung cancer, recent research has suggested that the time between symptom onset and consultation can be long enough to plausibly affect prognosis. In this article, we present findings from a qualitative study involving in-depth interviews with patients who had been diagnosed with lung cancer (n = 11), and people who were at heightened risk of developing the disease (n = 14). Methods A grounded theory methodology was drawn upon to conduct thematic and narrative based approaches to analysis. Results The paper focuses on three main themes which emerged from the study: i) fatalism and resignation in pathways to help-seeking and the process of diagnosis; ii) Awareness of smoking risk and response to cessation information and advice. iii) The role of social and other networks on help-seeking. Key findings included: poor awareness among participants of the symptoms of lung cancer; ambivalence about the dangers of smoking; the perception of lung cancer as part of a homogenisation of multiple illnesses; close social networks as a key trigger in help-seeking. Conclusions We suggest that future smoking cessation and lung cancer awareness campaigns could usefully capitalise on the influence of close social networks, and would benefit from taking a ‘softer’ approach

Cerebrovascular assessments to help understand brain-related changes associated with aerobic exercise after stroke

Evidence suggests exercise is ‘good medicine’ post-stroke, yet consensus is lacking on the time to initiate, type, exertion level, and duration per session. It remains a challenge to identify outcome measures for stroke-exercise trials that are sufficiently sensitive to intervention parameters. Cerebrovascular assessments, namely cerebral blood flow and intracranial pulsatility, are herein discussed as examples of quantitative brain-specific measures that may be useful to monitor exercise-related brain changes and help to guide stroke rehabilitation interventions. Bullets:Cerebral blood flow and arterial stiffness are potential vascular targets for stroke exercise trials.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Natural History and Consequences of Nonunion in Mandibular and Maxillary Free Flaps

To describe the natural history of bone segment union in head and neck free flap procedures and detail the association of poor segment union with postoperative complications. Case series with chart review. Single tertiary care referral center. Patients with mandibular or maxillary defects reconstructed with osseous or osteocutaneous free flaps were analyzed (n = 104). Postoperative computed tomography or positron emission tomography/computed tomography scans were reviewed for signs of osseointegration and nonunion. Postoperative wound complications were correlated with imaging findings. Thirty-seven percent of appositions had partial union on nonunion. Appositions between osteotomized free flap segments form complete unions at a higher rate than appositions with native bone (65% vs 53%, = .0006). If an apposition shows a gap of ≥1 mm, the chances of failing to form a complete union are greatly increated (79% vs 8%, = .0009). Radiographic nonunion was associated with an increased likelihood of postoperative wound complications (40% vs 19%, = .025) and in most cases was present before development of complications. Radiographic evidence of partial union or nonunion of free flap osseous segments greatly exceeds reported rates of clinically evident nonunion. Unions likely form between free flap appositions before unions to the native bone. If initial bone segments are >1-mm apart, the chance of progression to complete union is low. Incomplete osseointegration appears to be a marker for development of wound complications

Long-Term Complications of Osteocutaneous Free Flaps in Head and Neck Reconstruction

Objective To determine the frequency at which patients with osteocutaneous free flap reconstruction of the head and neck develop long-term complications and identify predisposing perioperative factors. Study Design A prospectively maintained database of free flaps performed at a single institution over a 10-year period was queried. Setting Single tertiary care referral center. Subjects and Methods In total, 250 osseous or osteocutaneous free flaps (OCFFs) for mandibular or maxillary reconstruction were analyzed. Data were collected on demographics, preoperative therapy, resection location, adjuvant treatment, complications, and subsequent surgeries, and multivariate analysis was performed. Subgroup analysis based on perioperative factors was performed. Results The median follow-up time was 23 months. In 185 patients with at least 6 months of follow-up, 17.3% had at least 1 long-term complication, most commonly wound breakdown, fistula or plate extrusion (13.5%), osteoradionecrosis or nonunion (6.5%), and infected hardware (5.9%). Prior chemoradiotherapy and cancer diagnosis predisposed patients to long-term complications. At the 5-year follow-up, 21.7% of patients had experienced a long-term complication. Conclusions Long-term complications after OCFF occurred in 17% of patients. In this series, a preoperative history of chemoradiation and those undergoing maxillary reconstruction were at high risk for the development of long-term complications and thus warrant diligent follow-up. However, OCFFs can often enjoy long-term viability and survival, even in the case of perioperative complications and salvage surgery

Adolescence and the next generation

Adolescent growth and social development shape the early development of offspring from preconception through to the post-partum period through distinct processes in males and females. At a time of great change in the forces shaping adolescence, including the timing of parenthood, investments in today’s adolescents, the largest cohort in human history, will yield great dividends for future generations.JRC.A.5-Scientific Developmen