Performance of Partially Fluorinated Polyimide Insulation for Aerospace Applications

Polyimide has been used extensively as the primary wiring insulation in commercial planes, military aircraft, and space vehicles due to its low weight, high service temperature, and good dielectric strength. New failure modes, however, have been associated with the use of polyimide because of the susceptibility of the insulation to pyrolization and arc tracking. A new wiring construction utilizing partially fluorinated polyimide insulation has been tested and compared with the standard military polyimide wire. Electrical properties which were investigated include AC corona inception and extinction voltages (sea level and 60,000 feet), time/current to smoke, and wire fusing time. The two constructions were also characterized in terms of their mechanical properties including abrasion resistance, dynamic cut through, and notch propagation. These test efforts and the results obtained are presented and discussed

Ileus Biliaire : A Propos D’un Cas Clinique

Introduction: Gallstone ileus is a rare mechanical occlusion. It is caused by the enclosure of biliary macro lithiasis in a portion of the digestive tract resulting from a digestive bile fistula. We report a clinical case to discuss therapeutic modalities through a review of the literature. Medical observation: We report the case of a 77-year-old patient who was hospitalized in the Nephrology department of the university hospital in Montpellier for functional kidney failure and dehydration from vomiting and diarrhea. The none-injected abdominal-pelvic CT scan showed a gallstone ileus with 5 enclaved duodenum, jejunum and ileum lithiasis resulting into a small bowel obstruction. There are no signs of acute cholecystitis. The management was simple by enterolithotomy surgery alone after fixing of hydro electrolyte imbalance. The after surgery sequence was simple. Conclusion: Gallstone ileus is a rare surgical condition. The high mortality rate in the management of this condition makes enterolithotomy the least invasive and recommended method

Prise En Charge Des Anévrismes Artériels Dans Un Centre Africain Non Spécialisée

Introduction: Arterial aneurysms affect 7 to 8% of people over 65 in the West and are the 2nd leading cause of death in these countries. In Africa this frequency is poorly evaluated. The objective of this work is to report the management of arterial aneurysms at the National Hospital of Niamey (HNN). Patients and methods: This was a retrospective, descriptive study over a period of eight (8) years from January 2009 to December 2016, performed in the surgical departments of the National Hospital of Niamey. Included in the study were patients of both sexes, hospitalized and / or operated for arterial aneurysm. Not included were patients treated for arterial aneurysm with incomplete records or those concerning the neurosurgical sphere. Results: During the study period, 17,748 patients were hospitalized in the general surgery departments, including 16 patients for arterial aneurysm, or 0.09% of surgical pathologies. There were 13 men (81.25%) and 3 women (18.75%), or a sex ratio of 4.33. The average age was 55.75 years with extremes ranging from 25 years old to 90 years old. The circumstances of discovery of the aneurysms were swelling of the antero-internal aspect of the thigh in 7 cases (43.75%), abdominal mass 6 cases (37.50%), then 2 cases (12.50%) of chest pain and incidental discovery in 1cas (6.25%). The most common risk factor was high blood pressure with 43.75% (7 cases). The aneurysm sat on the femoral artery in 43.75% (n = 7), of which 6 on the deep femoral and 1 on the superficial femoral, on the infrarenal aorta in 31.25% (n = 5), on thoracic aorta 12.50% (n = 2), on the iliac artery 12.50% (n = 2). For the diagnosis the angioscanner is realized in all the patients and in addition Doppler ultrasound in 43, 75% of cases. Twelve (12) patients benefited from curative surgical intervention by prosthetic graft by PTFE in 58.33% of cases and by Dacron in 41.66%. The average stay was 29.75 days and the immediate operative followup was complicated by thrombosis in 12.5% and parietal suppurations in 6.25%. We recorded two (2) deaths, ie 12.5% among non-operated patients. Conclusion: Arterial aneurysms are rare diseases at the HNN. Conventional surgery is the treatment performed in our patients. The postoperative course was simple in most cases

Evaluation of Wiring Constructions for Space Applications

A NASA Office of Safety and Mission Assurance (OS&MA) program to develop lightweight, reliable, and safe wiring insulations for aerospace applications is being performed by the NASA Lewis Research Center (LeRC). As part of this effort, a new wiring construction utilizing high strength PTFE (poly tetrafluoroethylene) as the insulation has been tested and compared with the existing military standard polyimide-based MIL-W-81381 wire construction. Electrical properties which were investigated included ac corona inception and extinction voltages (sea level and 60,000 feet), time/current to smoke, and wire fusing time. The two constructions were also characterized in terms of their mechanical properties of flexural strength, abrasion resistance (23 C and 150 C), and dynamic cut-through (23 C and 200 C). The results obtained in this testing effort are presented and discussed in this paper

Cholécystectomies Laparoscopiques Pour Cholécystite Aigue Lithiasique Versus Lithiase Vésiculaire Symptomatique

Introduction: The aim of this work was to highlight the therapeutic and prognostic difficulties between a laparoscopic cholecystectomy for acute gallstone cholecystitis (CAL) and uncomplicated symptomatic vesicular lithiasis (LVS) as well as the reasons for conversion to laparotomy. Patients and Methods: This was a prospective comparative and analytic study over 18 months. Patients admitted and operated for CAL or LVS in the A Surgery Department of the National Hospital of Niamey (HNN) were included. Results: The study involved 61 patients divided into two groups. Group 1 (30 patients) corresponding to patients operated for CAL, group 2 (31 patients) corresponding to patients operated for LVS. Laparoscopic cholecystectomy accounted for 61% of all cholecystectomies performed and 1.45% of surgical activity during the same period. The average age in group 1 was 43.7 years with extremes of 14 and 61 years. In group 2, the average age was 38.9 years with extremes ranging from 12 to 55 years. Women were predominantly represented with 63.3% and 96.7% respectively for groups 1 and 2. Patients were overweight in 9 cases for group 1 (30% of cases) and 12 cases in group 2 (38%), 7% of cases). Hepatic colic was the main sign of appeal in all patients in both groups. In group 1; 26 out of 30 cases or 86.7% of cases had leukocytosis, whereas in group 2, leukocytosis was normal in 30 cases, ie 96.8% of cases. Accessibility of the vesicle was difficult in 73.3% of cases in group 1 against 22.6% of cases in group 2. The vesicle was distended and necrotic in groups 1 in 76.7% and 10 respectively. % of cases. On the other hand, in 25.8% of cases, the vesicle was distended and without any necrosis in group 2. The rate of conversion to laparotomy was 6.55% (4 cases) and exclusively concerned group 1. Operative follow-up immediate outcomes were simple in 98.34% of cases. The complications involved 2 patients in group 1 (1.66% of the total), including parietal suppuration and biliary leakage. Mean operative time was 68.7 min in group 1 versus 41.6 min in group 2. Mean duration of hospitalization was 4.3 days with extremes between 2 and 10 days in group 1 versus1,7 days with extremes ranging from 1 to 7 days in group 2. Mortality was zero. Conclusion: In recent years, laparoscopic surgery has made remarkable progress in Niger. Laparoscopic cholecystectomy seems to be more difficult to perform with significant morbidity in the case of CAL than LVS. The risk of per and postoperative complications can be estimated from the clinical data (acute cholecystitis or symptomatic vesicular lithiasis) and the surgeon's experience. In a cholecystectomy that lasts more than 2 hours, the cumulative risk of complications is highe

Influence of conjugated linoleic acid (CLA) or tetradecylthioacetic acid (TTA) on growth, lipid composition, fatty acid metabolism and lipid gene expression of rainbow trout (Oncorhynchus mykiss L.)

Our objective was to test the hypotheses that conjugated linoleic acid (CLA) and/or tetradecylthioacetic acid (TTA) would have beneficial effects on the nutritional quality of rainbow trout (Oncorhynchus mykiss) through decreased lipid content of flesh or viscera, and increased levels of beneficial fatty acids including accumulation of CLA or TTA themselves. The specific aims of this study were to determine the effects of CLA and TTA on growth performance, lipid and fatty acid metabolism, and selected gene expression in commercial sized trout grown in seawater. Trout were fed for eight weeks on fish meal and fish oil diets containing either 0.5% or 1% CLA, or 0.5% TTA. The effects of the supplemented fatty acids on growth, feed efficiency, lipid contents, class compositions and fatty acid compositions of flesh and liver were determined, along with liver highly unsaturated fatty acid synthesis, activities of key enzymes of fatty acid oxidation in liver and muscle, and expression of carnitine palmitoyltransferase-I (CPT-I) and fatty acyl desaturase and elongase genes. Neither functional fatty acid had any effect on growth parameters, condition factor, viscero- and hepato-somatic indices or fillet colour, and there were no mortalities in any of the treatments. Dietary CLA, but not TTA, decreased the lipid content of liver, but neither fatty acid had any significant effect on lipid class compositions of liver and flesh. Both CLA and TTA were incorporated into tissue lipids, with higher percentages found in flesh compared to liver. In addition, production of hexaene fatty acid by liver microsomes was increased by dietary CLA or TTA, and both functional fatty acids increased the proportion of n-3 fatty acids in liver mainly due to increased 20:5n-3 and 22:6n-3. However, the expression of fatty acyl Δ6 desaturase was significantly lower in fish fed CLA or TTA, whereas the expression of PUFA elongase was increased, significantly so in fish fed 1% CLA. CPT-I activity was increased by TTA in liver and red muscle, and acyl CoA oxidase activity was increased by TTA in liver and CLA at the higher dietary inclusion level in red muscle. There was a clear trend for CPT-I expression to be increased in fish fed 0.5% CLA or TTA in all tissues although this was only significant in white muscle. The results showed that both CLA and TTA had effects on lipid metabolism that partly support the hypotheses tested. Although CLA or TTA did not enhance growth parameters, feed conversion or potential yield, nutritional quality could be enhanced, and sea-run trout fed CLA or TTA could be beneficial in the human diet through provision of bioactive fatty acids, with no detrimental effects on 20:5n-3 or 22:6n-3 levels

Nerve Growth Factor mRNA Expression in the Regenerating Antler Tip of Red Deer (Cervus elaphus)

Deer antlers are the only mammalian organs that can fully regenerate each year. During their growth phase, antlers of red deer extend at a rate of approximately 10 mm/day, a growth rate matched by the antler nerves. It was demonstrated in a previous study that extracts from deer velvet antler can promote neurite outgrowth from neural explants, suggesting a possible role for Nerve Growth Factor (NGF) in antler innervation. Here we showed using the techniques of Northern blot analysis, denervation, immunohistochemistry and in situ hybridization that NGF mRNA was expressed in the regenerating antler, principally in the smooth muscle of the arteries and arterioles of the growing antler tip. Regenerating axons followed the route of the major blood vessels, located at the interface between the dermis and the reserve mesenchyme of the antler. Denervation experiments suggested a causal relationship exists between NGF mRNA expression in arterial smooth muscle and sensory axons in the antler tip. We hypothesize that NGF expressed in the smooth muscle of the arteries and arterioles promotes and maintains antler angiogenesis and this role positions NGF ahead of axons during antler growth. As a result, NGF can serve a second role, attracting sensory axons into the antler, and thus it can provide a guidance cue to define the nerve track. This would explain the phenomenon whereby re-innervation of the regenerating antler follows vascular ingrowth. The annual growth of deer antler presents a unique opportunity to better understand the factors involved in rapid nerve regeneration

Alterations in cerebral blood flow and cerebrovascular reactivity during 14 days at 5050 m

Upon ascent to high altitude, cerebral blood flow (CBF) rises substantially before returning to sea-level values. The underlying mechanisms for these changes are unclear. We examined three hypotheses: (1) the balance of arterial blood gases upon arrival at and across 2 weeks of living at 5050 m will closely relate to changes in CBF; (2) CBF reactivity to steady-state changes in CO2 will be reduced following this 2 week acclimatisation period, and (3) reductions in CBF reactivity to CO2 will be reflected in an augmented ventilatory sensitivity to CO2. We measured arterial blood gases, middle cerebral artery blood flow velocity (MCAv, index of CBF) and ventilation () at rest and during steady-state hyperoxic hypercapnia (7% CO2) and voluntary hyperventilation (hypocapnia) at sea level and then again following 2–4, 7–9 and 12–15 days of living at 5050 m. Upon arrival at high altitude, resting MCAv was elevated (up 31 ± 31%; P < 0.01; vs. sea level), but returned to sea-level values within 7–9 days. Elevations in MCAv were strongly correlated (R2= 0.40) with the change in ratio (i.e. the collective tendency of arterial blood gases to cause CBF vasodilatation or constriction). Upon initial arrival and after 2 weeks at high altitude, cerebrovascular reactivity to hypercapnia was reduced (P < 0.05), whereas hypocapnic reactivity was enhanced (P < 0.05 vs. sea level). Ventilatory response to hypercapnia was elevated at days 2–4 (P < 0.05 vs. sea level, 4.01 ± 2.98 vs. 2.09 ± 1.32 l min−1 mmHg−1). These findings indicate that: (1) the balance of arterial blood gases accounts for a large part of the observed variability (∼40%) leading to changes in CBF at high altitude; (2) cerebrovascular reactivity to hypercapnia and hypocapnia is differentially affected by high-altitude exposure and remains distorted during partial acclimatisation, and (3) alterations in cerebrovascular reactivity to CO2 may also affect ventilatory sensitivity

Geodetic and seismic constraints on some seismogenic zone processes in Costa Rica

New seismic and geodetic data from Costa Rica provide insight into seismogenic zone processes in Central America, where the Cocos and Caribbean plates converge. Seismic data are from combined land and ocean bottom deployments in the Nicoya peninsula in northern Costa Rica and near the Osa peninsula in southern Costa Rica. In Nicoya, inversion of GPS data suggests two locked patches centered at 14 ± 2 and 39 ± 6 km depth. Interplate microseismicity is concentrated in the more freely slipping intermediate zone, suggesting that small interseismic earthquakes may not accurately outline the updip limit of the seismogenic zone, the rupture zone for future large earthquakes, at least over the short (∼1 year) observation period. We also estimate northwest motion of a coastal “sliver block” at 8 ± 3 mm/yr, probably related to oblique convergence. In the Osa region to the south, convergence is orthogonal to the trench. Cocos-Caribbean relative motion is partitioned here, with ∼8 cm/yr on the Cocos-Panama block boundary (including a component of permanent shortening across the Fila Costeña fold and thrust belt) and ∼1 cm/yr on the Panama block–Caribbean boundary. The GPS data suggest that the Cocos plate–Panama block boundary is completely locked from ∼10–50 km depth. This large locked zone, as well as associated forearc and back-arc deformation, may be related to subduction of the shallow Cocos Ridge and/or younger lithosphere compared to Nicoya, with consequent higher coupling and compressive stress in the direction of plate convergence

Understanding the influences on successful quality improvement in emergency general surgery: learning from the RCS Chole-QuIC project

Abstract: Background: Acute gallstone disease is the highest volume Emergency General Surgical presentation in the UK. Recent data indicate wide variations in the quality of care provided across the country, with national guidance for care delivery not implemented in most UK hospitals. Against this backdrop, the Royal College of Surgeons of England set up a 13-hospital quality improvement collaborative (Chole-QuIC) to support clinical teams to reduce time to surgery for patients with acute gallstone disease requiring emergency cholecystectomy. Methods: Prospective, mixed-methods process evaluation to answer the following: (1) how was the collaborative delivered by the faculty and received, understood and enacted by the participants; (2) what influenced teams’ ability to improve care for patients requiring emergency cholecystectomy? We collected and analysed a range of data including field notes, ethnographic observations of meetings, and project documentation. Analysis was based on the framework approach, informed by Normalisation Process Theory, and involved the creation of comparative case studies based on hospital performance during the project. Results: Chole-QuIC was delivered as planned and was well received and understood by participants. Four hospitals were identified as highly successful, based upon a substantial increase in the number of patients having surgery in line with national guidance. Conversely, four hospitals were identified as challenged, achieving no significant improvement. The comparative analysis indicate that six inter-related influences appeared most associated with improvement: (1) achieving clarity of purpose amongst site leads and key stakeholders; (2) capacity to lead and effective project support; (3) ideas to action; (4) learning from own and others’ experience; (5) creating additional capacity to do emergency cholecystectomies; and (6) coordinating/managing the patient pathway. Conclusion: Collaborative-based quality improvement is a viable strategy for emergency surgery but success requires the deployment of effective clinical strategies in conjunction with improvement strategies. In particular, achieving clarity of purpose about proposed changes amongst key stakeholders was a vital precursor to improvement, enabling the creation of additional surgical capacity and new pathways to be implemented effectively. Protected time, testing ideas, and the ability to learn quickly from data and experience were associated with greater impact within this cohort