In this original and controversial book, historian and philosopher Reviel Netz explores the development of a controlling and pain-inducing technology—barbed wire. Surveying its development from ...1874 to 1954, Netz describes its use to control cattle during the colonization of the American West and to control people in Nazi concentration camps and the Russian Gulag. Physical control over space was no longer symbolic after 1874.
This is a history told from the perspective of its victims. With vivid examples of the interconnectedness of humans, animals, and the environment, this dramatic account of barbed wire presents modern history through the lens of motion being prevented. Drawing together the history of humans and animals, Netz delivers a compelling new perspective on the issues of colonialism, capitalism, warfare, globalization, violence, and suffering. Theoretically sophisticated but written with a broad readership in mind, Barbed Wire calls for nothing less than a reconsideration of modernity.
There is a strong interest in the development of high-temperature electrical machines, both from academic research and industrial consumers. Conventional electrical machines cannot operate much ...beyond 250°C, and this limits their application in certain sectors such as oil, gas, and aerospace. The key technology for high-temperature operation is high-temperature wire insulation systems for the motor windings. This study presents an experimental study on the temperature dependence of the wire insulation resistance of a standard Class H (180°C) enamel wire, a high-temperature MAGNETEMP CA-200 wire, a photonis glass-coated wire, a mica-taped VonRoll SK650 wire, a ceramic-based CERAFIL500 wire, and a newly developed S-2 glass-fibre insulated wire. The results show that motor operation above ∼300°C for any length of time using conventional polymer-based wire is difficult. It is possible, however, to operate motors up to 600°C using inorganic insulation coatings. The new wire using the S-2 glass-fibre insulation performed very well showing good insulation resistance up to 600°C: excellent flexibility and robustness, capable of very small bend diameters, and with packing factors almost identical to the conventional copper wire.
Category:
Midfoot/Forefoot; Trauma
Introduction/Purpose:
The great toe plays a large role in activity, including maintenance of balance and substantial weight bearing capabilities. Fractures of the ...hallux distal phalanx, especially when displaced or unstable, can lead to significant dysfunction of the interphalangeal joint (IP) and pain and may need operative intervention. Surgical options include wire pinning, screw fixation, external fixation, arthrodesis, or amputation. For patients with significant comminution and shortening who would like to attempt toe salvage without fusion, external fixation can lead to great outcomes. Unfortunately, the use of these devices is hindered by cost, size, and availability. We recommend the use of a novel low cost external fixation device that can be made intraoperatively using common materials found in the operative room.
Methods:
A 27-year-old female, with a severely comminuted right distal phalanx fracture with interphalangeal (IP) joint dislocation, presented 4 days after a skiing accident. We discussed treatment may require IP joint arthrodesis or partial amputation, however, salvage fixation could be attempted initially. First, a transverse percutaneous wire was placed through the distal phalanx tip since the fragment was still mostly intact. The wire exited the skin medially. Two Kocher clamps to each side of the wire were applied for distraction of the fracture site while simultaneous manual manipulation of the more proximal fragments was performed. Once reduced, three more proximal transverse wires were placed through a 3cc syringe, which acted as a rail to hold the fracture length stable. The distal transverse wire was then impaled through the rail so that all four wires were within the rail providing two points of fixation in the distal phalanx and proximal phalanx.
Results:
The patient's weight-bearing status was non-weight bearing to the right lower extremity for 6 weeks. This was actually being dictated by the more proximal tibial plateau fracture for which she was non-weight bearing. With regard specifically to the hallux fracture, she could have been heel weight beared immediately. At her most recent post-operative visit at 6 weeks, she was doing well with minimal pain. The external fixation device was removed in clinic and she was transitioned to a post-op shoe and allowed to weight bear as tolerated. She was motor and sensate intact with the ability to actively range her IP joint. Radiographs at the most recent visit revealed excellent alignment of the toe with minimal articular step off.
Conclusion:
With severely unstable hallux distal phalanx fractures, operative intervention should be considered. For those with a significant degree of comminution who still would like to undergo salvage fixation, external fixation is an excellent option. Unfortunately, the use of these devices is hindered by cost, size, and availability. Hand surgeons solved this problem by introducing small, low cost external fixators composed of common materials such as needle sheaths, IV cannulas, and syringes. We adapted their model to the toes and were able to obtain great clinical outcomes with low cost, all the while maintaining the patient's expectations for cosmesis.
Category:
Bunion; Midfoot/Forefoot
Introduction/Purpose:
Distal 1st metatarsal chevron osteotomy is one of the most frequently performed procedures for treatment of mild to moderate hallux valgus, ...though the optimal method of fixation remains in question. The use of Kirschner wires (K-wires) is an established technique of temporary internal fixation that offers a simple and cost-effective strategy. Previous studies have reported removal of K-wires ranging from 4-8 weeks following a chevron osteotomy, though even earlier removal may be acceptable and serve to decrease the risk of complications. The purpose of this study was to determine if early removal of K-wires is adequate to maintain correction of a hallux valgus deformity following distal 1st metatarsal chevron osteotomy.
Methods:
We conducted a retrospective review of patients who had their 1st metatarsal K-wire removed at their first (2week) postoperative visit after undergoing primary chevron osteotomy for treatment of a hallux valgus deformity with a single foot and ankle fellowship-trained orthopaedic surgeon from 2010-2018. Exclusion criteria consisted of revision osteotomies, K-wire removal >=21 days postoperatively, concomitant midfoot or hindfoot procedures, and lack of preoperative or at least 3-month postoperative radiographs. Preoperative, 6-week, 3-month, and longer-term intermetatarsal angles (IMA) were measured on weightbearing anteroposterior (AP) radiographs by an individual blinded to and not involved in the care of the patients. The pre- and postoperative tibial sesamoid position according to the Hardy and Clapham classification (grades 1-7) was also recorded on those with longer-term AP radiographs on file. From 2010-2018, 275 patients underwent 295 primary chevron osteotomies by the senior author, with 72 osteotomies (24.4%) excluded, leaving 223 (75.6%) available for analysis.
Results:
Patients had a mean preoperative IMA of 11.4 +- 2.0 degrees. At 6 weeks, 3 months, and longer-term follow-up averaging 24.6 months, patients had mean IMA of 3.8 +- 1.7, 4.6 +- 1.7, and 4.6 +- 2.2 degrees, respectively, all of which were significantly less (P<0.0001) than the mean preoperative IMA. Of those with longer-term follow-up (n=56, 25.1%), the tibial sesamoid position decreased from 4.6 +- 0.8 preoperatively to 2.3 +- 0.7 at 6 weeks, 2.4 +- 0.8 at 3 months, and 2.6 +- 0.9 at final follow-up. All 3 postoperative time points of tibial sesamoid positions were significantly less (P<0.0001) than the mean preoperative position.
Conclusion:
Our findings demonstrate that removal of K-wires less than 3 weeks following a distal 1st metatarsal chevron osteotomy is sufficient to maintain correction of hallux valgus deformity. The loss of correction in this study is in line with previous studies, where K-wires were removed at later postoperative time points. Delayed wire removal has been shown to lead to increased complications, such as pin tract infection and bending or breakage of the K-wire, which can require not only additional office visits but also potential revision procedures. Removing the K-wire in the early postoperative period should be considered effective and safe.
Category:
Bunion, Midfoot/Forefoot
Introduction/Purpose:
The lapidus procedure is a longstanding operation performed for the treatment of hallux valgus deformity with a concomitant hypermobile first ...ray. Orthopaedic surgeons have a myriad of options to choose from in performing the lapidus procedure. The implantation of orthopaedic implants comes with the risk of iatrogenic injury to surrounding anatomy. Several cadaveric studies in the humerus and femur have described potential neurovascular structures at risk during placement of intramedullary nail systems. The purpose of this study was to determine the proximity of nail insertion and interlocking mechanisms in the Lapidus Phantom Intramedullary Nail System (Paragon 28, Inc.) to neurologic and tendinous structures in the foot.
Methods:
A titanium intramedullary nail was inserted from the first metatarsal to the medial cuneiform spanning the first tarsometatarsal joint in 10 fresh-frozen cadaver feet. K-wires were inserted in the proximal lateral, proximal medial, and distal medial-to-lateral interlock screw paths. The tibialis anterior tendon, extensor hallucis longus tendon, and superficial peroneal nerve were carefully dissected and exposed, and the distance from each of these anatomic landmarks were then measured and recorded from four different aspects of the nail: Proximal lateral interlocking screw path, proximal medial interlocking screw path, nail insertion, distal interlocking screw path. Distances were averaged, ranges were determined.
Results:
The tibialis anterior tendon was in closest proximity to the proximal medial interlock K-wire with an average distance of 0.4 mm. The proximal medial interlock bisected the tibialis anterior tendon in three of the specimens. The extensor hallucis longus tendon was in closest proximity to the nail insertion with an average distance of 1.2 mm. A branch of the superficial peroneal nerve was in closest proximity to the distal interlock K-wire with an average distance of 7.5 mm, however, the nerve came in direct contact with the proximal medial interlock K-wire in two of the specimens.
Conclusion:
The Lapidus intramedullary nail’s proximal medial interlock screw poses the greatest threat to the tibialis anterior tendon, with the distance from the tendon to the interlock K-wire being 3 mm or less in all specimens tested. The extensor hallucis longus tendon is at risk of injury with insertion of the nail. Medial to lateral interlocking poses the greatest danger to a branch of the superficial peroneal nerve. Blunt dissection should be performed using this system with a path to bone before instrumentation to reduce the risk of nerve and tendon injury in the foot.
Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing ...hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and from brass wire electrodes to the latest coated wire electrodes. Wire electrodes have been developed to help user demand and needs through maximum productivity and quantity by choosing the best wire. In the final part of the paper, the possible trends for future WEDM electrode research are discussed.
This paper presents recent results from our continued development of a 0.5 T whole-body MRI magnet at the Francis Bitter Magnet Laboratory. HyperTech Research Corp. (Columbus, OH) manufactures the ...Formula Omitted conductor for this project. During the past year, we have found that our technique, originally developed successfully to splice unreacted multifilament Formula Omitted wires, works much better, i.e., of higher reliability, with unreacted monofilament Formula Omitted wires. This has led us to wind the entire coil components in our persistent-mode MRI magnet with unreacted monofilament Formula Omitted wire, having a Formula Omitted core of 0.4 mm in diameter, an overall diameter of 0.8 mm bare, 1 mm S-glass insulated. To verify that these coils would not suffer from flux jumping, as they would if wound with monofilament NbTi wire, magnetization studies were performed on monofilament wires of Formula Omitted and NbTi (as a reference) at 4.2 K. For the monofilament Formula Omitted wire, the results were affirmative. To further ensure the absence of flux jumping that may quench these current-carrying coils, two test coils were wound with unreacted monofilament Formula Omitted wire. One Formula Omitted coil was operated in driven mode, while the other Formula Omitted coil, equipped with a persistent current switch and terminated with a superconducting joint, was operated in persistent mode. The operating temperature range was 4.2-15 K for these Formula Omitted coils. The driven mode coil was operated in self-field. The persistent mode coil achieved a persistent current of 100 A, corresponding to a self-field of Formula Omitted1 T in the winding, for 1 hour with no measurable decay. Both test coils were operated quench free.
Abstract
Aiming at enhancing the forward and inversion efficiency of grounded long wire source TEM (Transient ElectroMagnetic method), a new rapid layered medium forward method is proposed in the ...paper. This forward method is based on two points, one is to approximate the vertical magnetic component in frequency domain of a grounded long wire source by the response of several circular loops, and the other is to introduce the technique of "flow through" into the digital filtering calculation of sinusoidal transformation. The result of model tests shows that the calculation efficiency of proposed method is improved greatly (dozens of times) compared with that of the conventional method.
Simple low-cost interfacing circuits for resistance thermometers are proposed in this paper. The proposed circuits are designed to provide many salient features, including simplicity of architecture, ...lead-wire compensation, constant-current excitation, and requirement of minimal number of analog-to-digital converters for digitization. The first of the proposed circuits uses a twin-Op-amp signal conditioner for three-wire sensor. This circuit is then modified to act as an efficient front-end for four-wire resistance thermometer, and thus negate the effect of lead-wire mismatches. The performance of the proposed circuits is extensively verified using experimental studies. Results show that the nonlinearity and relative error of the developed circuits is less than 0.05% and 0.32%, respectively, when tested with Pt1000 sensor. Finally, a comparison study is performed to show the superiority of the proposed techniques.
PDF
