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Sample records for acute tarsal tunnel

  1. Calcaneal osteomyelitis presenting with acute tarsal tunnel syndrome: a case report

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    Shariff Sajid

    2010-02-01

    Full Text Available Abstract Introduction Cases of acute tarsal tunnel syndrome are rare. To the best of our knowledge, we describe the only reported case of acute posterior tibial nerve compression resulting from adjacent haemotogenous pyogenic calcaneal osteomyelitis. Case presentation A previously healthy 38-year-old Caucasian woman developed symptoms of acute tarsal tunnel syndrome in her right foot over a six-day period. No antecedent trauma or systemic symptoms were noted. Magnetic resonance imaging and bone scan imaging, followed by surgical decompression and bone biopsy confirmed a diagnosis of Staphylococcus aureus calcaneal osteomyelitis. Her pain and paraesthesia disappeared after the operation, while her inflammatory markers normalised during a 12-week course of antibiotics. After four years she has remained asymptomatic without any indication of recurrence. Conclusion This case is not just unique in describing osteomyelitis as a cause of tarsal tunnel syndrome, because haemotogenous calcaneal osteomyelitis is in itself a rare pathology. We recommend considering infection as a differential diagnosis in patients presenting with acute tarsal tunnel syndrome.

  2. Tenosynovial osteochondromatosis of the tarsal tunnel

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    Sugimoto, Kazuya; Iwai, Makoto [Department of Orthopaedic Surgery, Saiseikai Nara Hospital, 4-643 Hachijo, Nara-shi, Nara (Japan); Kawate, Kenji; Yajima, Hiroshi; Takakura, Yoshinori [Department of Orthopaedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara-shi, Nara (Japan)

    2003-02-01

    A case of tenosynovial osteochondromatosis in the tarsal tunnel in a 23-year-old man is presented. The lesion was treated surgically, and multiple osteochondromas were excised, which had no continuity with any tarsal bone or joint cavity but did with the sheaths of the flexor digitorum longus and flexor hallucis longus. Histologic examination of the lesion showed a fibrous capsule, hyaline cartilage and extensive areas of cancellous bone. Necrosis and mitosis were absent in the hyaline cartilage and there were no synovial nodules indicative of synovial metaplasia. The macroscopic findings showed ''end-stage'' tenosynovial osteochondromatosis. There was no evidence of recurrence 5 years after operation, and the patient remains free of symptoms. (orig.)

  3. Tarsal tunnel disease and talocalcaneal coalition: MRI features

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    FitzGerald Alaia, Erin; Rosenberg, Zehava Sadka; Bencardino, Jenny T.; Ciavarra, Gina A.; Petchprapa, Catherine N. [New York University Langone Medical Center, New York, NY (United States); Rossi, Ignacio [New York University Langone Medical Center, New York, NY (United States); Centro de Diagnostico Dr. Enrique Rossi, Buenos Aires (Argentina)

    2016-11-15

    To assess, utilizing MRI, tarsal tunnel disease in patients with talocalcaneal coalitions. To the best of our knowledge, this has only anecdotally been described before. Sixty-seven ankle MRIs with talocalcaneal coalition were retrospectively reviewed for disease of tendons and nerves of the tarsal tunnel. Interobserver variability in diagnosing tendon disease was performed in 30 of the 67 cases. Tarsal tunnel nerves were also evaluated in a control group of 20 consecutive ankle MRIs. Entrapment of the flexor hallucis longus tendon (FHL) by osseous excrescences was seen in 14 of 67 cases (21 %). Attenuation, split tearing, tenosynovitis, or tendinosis of the FHL was present in 26 cases (39 %). Attenuation or tenosynovitis was seen in the flexor digitorum longus tendon (FDL) in 18 cases (27 %). Tenosynovitis or split tearing of the posterior tibial tendon (PT) was present in nine cases (13 %). Interobserver variability ranged from 100 % to slight depending on the tendon and type of disease. Intense increased signal and caliber of the medial plantar nerve (MPN), indicative of neuritis, was seen in 6 of the 67 cases (9 %). Mildly increased T2 signal of the MPN was seen in 15 (22 %) and in 14 (70 %) of the control group. Talocalcaneal coalitions may be associated with tarsal tunnel soft tissue abnormalities affecting, in decreasing order, the FHL, FDL, and PT tendons, as well as the MPN. This information should be provided to the referring physician in order to guide treatment and improve post-surgical outcome. (orig.)

  4. The value of MRI iniIdiopathic tarsal tunnel syndrome by measuring the cross-sectional area of tarsal tunnel

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    Kim, Min Jung; Jeong, Yu Mi; Lee, Sheen Woo; Choi Seung; Kim, Jeong Ho; Park, Hong Gi [Gachon University, Gil Hospital, Incheon (Korea, Republic of)

    2015-03-15

    The purpose of this study was to evaluate the use of MRI as a diagnostic test in tarsal tunnel syndrome. There are no published reports with this aim and no diagnostic standard for idiopathic tarsal tunnel syndrome (TTS) using imaging modalities. We retrospectively searched our Picture Archiving and Communication System data and medical records to identify patients who were clinically and electomyographically diagnosed with idiopathic TTS without space-occupying lesion on MRI. Twenty five patients were included in the patient group. Another twenty-five patients who underwent ankle MRI for Achilles tendon disease were selected and included in the control group. Cross-sectional areas (CSA) of tarsal tunnel were manually measured independently by two radiologists who were blinded to clinical and surgical results, using three-dimensional reconstruction software in our hospital. Measurements were done on axial images at three levels (level 1, tibiotalar joint level; level 2, medial malleolar tip level; level 3, sustentaculum tali level). Patient and control group data were statistically analyzed by the Mann-Whitney test. The mean values of CSA at levels 1, 2, and 3 of the tarsal tunnel were 87.8 mm2, 98.2 mm2, and 105.2 mm2, respectively in the patient group; and 100.0 mm2, 113.8 mm2, and 127.9 mm2 in the control group, respectively, in reader 1; and 86.2 mm2, 97.6 mm2, 105.2 mm2, respectively in the patient group; and 99.7 mm2, 112.3 mm2, 124.4 mm2, respectively, in the control group, in reader 2. The mean CSA in the patient group was significantly less than that of the control group at all three levels (p < 0.05). Intra-class correlation coefficient value between reader 1 and reader 2 were 0.98 in group 1, and 0.97 in group 2, respectively. MRI can be helpful in the assessment of idiopathic tarsal tunnel syndrome. CSA measurements of tarsal tunnel at each level may predict TTS even though there are no space occupying lesions in the tarsal tunnel on MRI.

  5. The Usefulness of the Preoperative Magnetic Resonance Imaging Findings in the Evaluation of Tarsal Tunnel Syndrome

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    Jung, Hyun Jin; Lee, Sheen Woo; Jeong, Yu Mi; Choi, Hye Young; Kim, Hyung Sik [Dept. of Radiology, Gil Hospital, Gacheon University College of Medicine, Incheon (Korea, Republic of); Park, Hong Gi; Kwak, Ji Hoon [Dept. of Orthopedic Surgery, Gil Hospital, Gacheon University College of Medicine, Incheon (Korea, Republic of)

    2012-02-15

    The purpose of this study was to access the diverse conditions that lead to the clinical manifestations of tarsal tunnel syndrome and evaluate the usefulness of magnetic resonance imaging (MRI) in preoperative evaluation. Thirty-three patients who underwent ankle MRI and surgery under the impression of tarsal tunnel syndrome were retrospectively analyzed. The findings on ankle MRI were categorized into space occupying lesions within the tarsal tunnel, space occupying lesions of the tunnel wall, and non-space occupying lesions. Associated plantar muscle atrophy was also evaluated. Medical records were reviewed for correlation of nerve conduction velocity (NCV) and surgical findings. There were 21 space occupying lesions of the tarsal tunnel, and eight lesions of tarsal tunnel wall. There were three cases with accessory muscle, three with tarsal coalition, five with ganglion cysts, one neurogenic tumor, five flexor retinaculum hypertrophy, three varicose veins, and nine with tenosynovitis of the posterior tibialis, flexor digitorum longus, or flexor hallucis longus tendon. One patient was found to have a deltoid ligament sprain. Of the 32, eight patients experienced fatty atrophic change within any one of the foot muscles. NCV was positive in 79% of the MRI-positive lesions. MRI provides detailed information on ankle anatomy, which includes that of tarsal tunnel and beyond. Pathologic conditions that cause or mimic tarsal tunnel syndrome are well demonstrated. MRI can enhance surgical planning by indicating the extent of decompression required, and help with further patient management. Patients with tarsal tunnel syndrome can greatly benefit from preoperative MRI. However, it should be noted that not all cases with tarsal tunnel syndrome have MRI-demonstrable causes.

  6. Case Study of Oriental Medicine Treatment with acupotomy Therpy of the Tarsal tunnel Syndrome

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    Lim Na-ra

    2009-03-01

    Full Text Available Purpose : In order to estimate clinical effects of Oriental Medicine Treatment with acupotomy therapy of Tarsal tunnel Syndrome Methods : From 5th November, 2008 to 8th November, 2008, 1 male patient diagnosed as Tarsal tunnel syndrome(clinical diagnosed was treated with general oriental medicine therapy (acupuncture, moxibustion, cupping, physical therapy, herbal medication and acupotomy. Results : The patient's Rt foot paresthesia, pain were remarkably improved. Conclusions : This study demonstrates that oriental medical treatment with acuputomy therapy has notable effect in improving symptoms of tarsal tunnel syndrome. as though we had not wide experience in this treatment, more research is needed.

  7. Bilateral anterior tarsal tunnel syndrome variant secondary to extensor hallucis brevis muscle hypertrophy in a ballet dancer: a case report.

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    Tennant, Joshua N; Rungprai, Chamnanni; Phisitkul, Phinit

    2014-12-01

    We present a case of bilateral anterior tarsal tunnel syndrome secondary EHB hypertrophy in a dancer, with successful treatment with bilateral EHB muscle excisions for decompression. The bilateral presentation of this case with the treatment of EHB muscle excision is the first of its type reported in the literature.

  8. Effects on the Tarsal Tunnel Following Malerba Z-type Osteotomy Compared to Standard Lateralizing Calcaneal Osteotomy.

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    Cody, Elizabeth A; Greditzer, Harry G; MacMahon, Aoife; Burket, Jayme C; Sofka, Carolyn M; Ellis, Scott J

    2016-09-01

    Tarsal tunnel syndrome is a known complication of lateralizing calcaneal osteotomy. A Malerba Z-type osteotomy may preserve more tarsal tunnel volume (TTV) and decrease risk of neurovascular injury. We investigated 2 effects on the tarsal tunnel of the Malerba osteotomy compared to a standard lateralizing osteotomy using a cadaveric model: (1) the effect on TTV as measured by magnetic resonance imaging (MRI) and (2) the proximity of the osteotomy saw cuts to the tibial nerve. Ten above-knee paired cadaveric specimens underwent MRI of the ankle to obtain a baseline measurement of TTV. One foot in each pair received a standard lateralizing calcaneal osteotomy, with the other foot receiving a Malerba osteotomy. MRIs were performed after each of 3 increasing amounts of lateral displacement, which were accompanied by increasing amounts of wedge resection in the Malerba osteotomy group. TTV was measured on MRI using previously described and validated parameters. Differences in TTV with osteotomy type, displacement, and their interaction were assessed with generalized estimating equations. After all MRIs were completed, each specimen was dissected and the nearest distance of tibial nerve branches to the osteotomy site was measured. Baseline TTV averaged 13 229 ± 2354 mm(3) and did not differ between groups (P = .386). TTV decreased on average by 7% after the first translation, 14% after the second, and 27% after the third (P osteotomies versus those with Malerba osteotomies (P = .578). At least one of the major branches of the tibial nerve crossed the osteotomy site in 5 of 5 specimens that received the Malerba osteotomy versus 2 of 5 that received a standard osteotomy. Regardless of osteotomy type, lateralizing calcaneal osteotomy decreased TTV. In all specimens, the osteotomy was at the level of branches of the tibial nerve. Our results demonstrate that lateralizing calcaneal osteotomies must be performed with care to avoid excessive lateral translation as well as

  9. 踝管综合征的显微手术治疗%Microsurgical Treatment in Tarsal Tunnel Syndrome

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    王换新; 吴学建; 李锦永; 程学锋

    2013-01-01

    Objective To investigate the causes of tarsal tunnel syndrome, and diagnosis and microsurgical treatment. Methods From March 2003 to June 2010, 21 cases of tarsal tunnel syndrome were treated, including 15 males and 6 females,in which the age range was from 20 to 56 years old, and treating time was durating from 2 years to the shortest 1 month. 21 patients had a history of trauma in Meases: 11 cases of ankle sprain, 3 fractures, 3 cases of ganglion cyst, 2 case of neurilemoma, and 2 lipoma. flexor support was fully open to expose the tarsal tunnel,and the pathological changes within the organization were observed. For example, the ganglion cyst, osteo-phyte formation were removed, and varicose vein ligation group was cut off, thickening of the plantar fascia was open for decompression. Nerve in lesions was reteased under the operating microscope. Results The patients were followed up,with the longest time of 3.5 years, the shortest time of 1 year,and an average of 2 years and 2 months. 17 patients recovered well, with normal sensory - motor; 3 cases feel back to normal and foot muscle partially restorated; 1 patient feels most of the recovery, and the foot muscle did not recover. Conclusion Tarsal tunnel syndrome is relatively rare, has not yet attracted the attention of clinicians, and is often misdiagnosed. Once it being diagnosed, when conservative treatment fails,dot tors should seize the opportunity to line neurolysis treatment.%目的 探讨踝管综合征的诊断及显微手术治疗.方法 2003年3月~ 2010年6月,采用显微外科技术治疗踝管综合征21例.男性15例,女性6例.患者年龄20~56岁,平均年龄35岁.病程最长2年,最短1个月.21例中14例有外伤史:11例踝关节扭伤;3例跟骨骨折.4例腱鞘囊肿;2例脂肪瘤,1例神经鞘瘤.手术方法:完全打开屈肌支持带,显露踝管,观察其内组织的病理变化情况.如腱鞘囊肿、骨赘形成予以切除,曲张静脉团予以结扎切断,跖筋膜增

  10. Acute carpal tunnel syndrome caused by peritendinitis calcarea. Case report.

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    Boström, L; Svartengren, G

    1993-01-01

    Two women presented with similar symptoms of acute pain in the hand that was diagnosed as acute carpal tunnel syndrome caused by peritendinitis calcarea. Radiological examinations in both cases showed calcifications in the carpal tunnel. Both patients were operated on immediately and the median nerve was decompressed. Both were completely relieved of pain after operation and hand function returned to normal.

  11. Liberação do túnel do tarso pela técnica endoscópica: uma proposta de acesso cirúrgico Endoscopic release of the tarsal tunnel: a suggested surgical approach

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    Marcelo José Cortez Bezerra

    2005-01-01

    Full Text Available Estabelecer em cadáveres, dois portais, através da delimitação de pontos anatômicos e linhas geométricas, que permitam o acesso ao Túnel do Tarso pela técnica videoendoscópica e comparar a abordagem no sentido proximal para distal com a reversa. Fizeram parte do estudo 18 cadáveres, com um total de 36 tornozelos. Partindo da técnica endoscópica bi-portal inicialmente descrita, e modificada neste estudo através da padronização de pontos anatômicos e linhas geométricas, o Túnel do Tarso foi liberado nos tornozelos esquerdos com a inserção do instrumental no sentido proximal para distal e o inverso nos direitos.Nos tornozelos direitos, houve secção completa do retináculo flexor em 15 casos (83,3% e parcial em 3 casos (16,67%. Nos esquerdos, a secção foi completa em 16 casos (88,89% e parcial em 2 casos (11,11%. O tempo operatório no lado direito foi em média 19,44 minutos e no esquerdo 18,33 minutos. Em nenhum caso foi observada lesão de estruturas neurovasculares. Com a técnica proposta a secção total do retináculo dos flexores foi obtida em todos os casos após a curva do aprendizado, sem lesão de estruturas anatômicas do túnel do Tarso, independente do sentido utilizado na via de acesso.To establish to portals in cadavers, using anatomical delimitation points and geometrical lines, which allows the acess to the tarsal tunnel by the video-endoscopic technique and the comparison between the proximal-distal direction approach with the reverse one. This trial has included 18 cadavers and 36 ankles were studied. Starting with the biportal endoscopic technique, initially described and modified in this trial through geometrical lines and anatomical points delimitation, the tarsal tunnel was released in left ankles with the insertion of instruments using proximal-distal direction and the opposite to the right ankles. There were, in the right ankles, complete section of flexor retinaculum in 15 cases (83,3% and partial

  12. Acute Cubital Tunnel Syndrome Secondary to Anconeus Epitrochlearis Muscle

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    Ying-Kan Law

    2015-12-01

    Full Text Available Cubital tunnel syndrome is the most common type of ulnar nerve entrapment that usually associates with chronic sensory and motor symptoms. Having anconeus epitrochlearis muscle is an uncommon cause of cubital tunnel syndrome. In this paper, the author introduces a case of cubital tunnel syndrome due to anconeus epitrochlearis muscle presenting with acute sensory, motor, and sympathetic symptoms. For such cases, there has been much controversy over the choices of surgical treatment, which can be excision of the muscle alone or together with ulnar nerve anterior transposition.

  13. Acute calcifying tendonitis--an unusual cause of carpal tunnel syndrome.

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    Din, R; Giannikas, K; El-Hadidi, M

    2001-03-01

    We report a rare case of acute calcifying tendinitis resulting in acute carpal tunnel syndrome. Acute medical staff should be aware of this condition and the importance of early referral to avoid long term median nerve neuropathy.

  14. [Acute carpal tunnel syndrome in a patient with Marfan syndrome].

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    Franke, J; Wenzel, W; Rehfuss, D; Keiner, H P; Manncke, K

    2008-05-01

    Acute carpal tunnel syndrome (ACTS) is rare and is mostly the result of fractures of the distal radius or the carpal bones. This paper gives the first report of an ACTS following contusion of the wrist as the result of an extensive haematoma of the flexor tendon sheath, which did not appear until 50 hours after the injury was sustained but then developed rapidly. The patient suffers from Marfan syndrome. This disease is associated with pathologic changes to the major vessels, and especially the aorta, and of the smaller peripheral vessels. It is assumed that the haematoma arose from an aneurysm of such a small vessel. The treatment of choice in ACTS is emergency incision of the carpal tunnel.

  15. Rhinosporidiosis of the tarsal conjunctiva

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    Akshay Gopinathan Nair

    2015-01-01

    Full Text Available Rhinosporidiosis is a rare infection caused by Rhinosporidium seeberi, an organism classified in its own class, mesomycetozoea. It commonly affects mucus membranes namely the nasal mucosa, pharynx and the conjunctiva. We present the case of an 8-year-old female who presented with a flat, red, vascular, fleshy, pedunculated mass arising from the tarsal conjunctiva of the right upper eyelid. The mass was completely excised. On histopathological examination, multiple sporangia were seen in various stages of degeneration, consistent with rhinosporidiosis. The diagnosis of rhinosporidiosis is based solely on its microscopic features, and the treatment is surgical excision. This condition is endemic in the temperate regions of the Indian subcontinent, but it has been known to occur even in the colder regions of North America and Eastern Europe. Although a rare clinical entity, the possibility of rhinosporidiosis must be borne in mind when evaluating any polypoidal conjunctival mass.

  16. Carpal-tarsal osteolysis with elbow involvement

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    McDonald, Kirsteen; Toms, Andoni P.; Marshall, Thomas J. [Norfolk and Norwich University Hospital, Department of Radiology, Norwich, Norfolk (United Kingdom); Armon, Kate [Norfolk and Norwich University Hospital, Department of Paediatrics, Norwich, Norfolk (United Kingdom); Johnson, Karl [Birmingham Children' s Hospital, Department of Radiology, Birmingham, West Midlands (United Kingdom)

    2007-11-15

    Carpal-tarsal osteolysis is a rare condition that manifests as the progressive resorption of carpal and tarsal bones in young children. The diagnosis of this condition is often difficult and delayed as the initial clinical presentation is non-specific. Radiographic changes occur gradually, are often not seen at presentation and depend on recognising loss of bone in the ossification centres of the carpus and tarsus. MRI demonstrates morphological abnormalities in the cartilaginous, as well as the osseous components, of the developing carpal and tarsal bones and therefore may be helpful in predating the radiographic changes. Ultrasound appears to contribute little to the diagnosis and may be misleading. Exclusion of other conditions, particularly juvenile idiopathic arthritis, is important in making the diagnosis. MRI can be useful in excluding an inflammatory arthropathy, and suggesting the diagnosis of carpal-tarsal osteolysis. (orig.)

  17. Subclinical Carpal Tunnel Syndrome in Patients with Acute Stroke

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    Soroosh Dabiri

    2012-07-01

    Full Text Available Background: Stroke is the first cause of morbidity all around the world. Entrapment neuropathies are a known complication of stroke. The objective of this study is to assess the frequency of subclinical carpal tunnel syndrome in the healthy and paretic hands of stroke patients.Methods: The authors performed nerve conduction study in the first three days after admission in 39 stroke patients without subclinical carpal tunnel syndrome and 30 days after admission. Electrophysiological studies were done in both paretic and non-paretic hands. Both ulnar and median nerves were studied.Results: After one month we found subclinical carpal tunnel syndrome in 16 paretic hands and 13 healthy hands. We did not find any difference in the frequency of carpal tunnel syndrome in two sides.Conclusion: The authors suggest that simultaneous different mechanisms may act in inducing carpal tunnel syndrome in both hands of hemiparetic patients.

  18. Giant epidermal cyst of the tarsal plate

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    Mohana Majumdar

    2012-01-01

    Full Text Available A 35-year-old male patient presented with a right upper eyelid mass with mechanical ptosis. The patient gave no history of trauma or surgery. On examination, there was a huge cystic mass fixed to the tarsal plate. Excisional biopsy with tarsectomy was done. Histopathology sections demonstrated a keratin-filled cyst arising from the tarsus. A thorough Pubmed search did not reveal an epidermal cyst of the tarsal plate of this size which was successfully managed. The incision was made in such a way that postoperative ptosis would be avoided. Excess skin was removed during the surgery.

  19. Placing of tunneled central venous catheters prior to induction chemotherapy in children with acute lymphoblastic leukemia

    DEFF Research Database (Denmark)

    Handrup, Mette Møller; Møller, Jens Kjølseth; Frydenberg, Morten

    2010-01-01

    BACKGROUND: Tunneled central venous catheters (CVCs) are inevitable in children with acute lymphoid leukemia (ALL). The aim of this study was to evaluate the risk of CVC-related complications in children with ALL in relation to timing of catheter placement and type of catheter. PROCEDURE: All...

  20. Peculiar chondroblastoma involving multiple tarsal bones

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    Fukunaga, Masaharu [Jikei University School of Medicine, Department of Pathology, Tokyo (Japan); the Jikei University Daisan Hospital, Department of Pathology, Tokyo (Japan); Asanuma, Kazuo [Jikei University School of Medicine, Department of Orthopedic Surgery, Tokyo (Japan); Irie, Takeo [Jikei University School of Medicine, Department of Radiology, Tokyo (Japan)

    2010-07-15

    A case of peculiar chondroblastoma involving multiple tarsal bones in a 49-year-old woman is described. The patient presented with pain and swelling of the right foot. Radiographs revealed a lytic expansile lesion of medial, intermediate, and lateral cuneiform bones, navicular, cuboid, and tarsal bones of the right foot, indicating a malignant tumor. Biopsies demonstrated a diffuse proliferation of round cells with eccentric and indented nuclei with longitudinal grooves and eosinophilic cytoplasm. Atypia was prominent, but mitotic figures were rare. The stroma was chondroid with focal chicken-wire calcification. On electron microscopy, the tumor exhibited chondroblastic features. The patient is alive with the tumor 7 years after radiotherapy. The tumor is considered a chondroblastoma with low malignant potential. (orig.)

  1. Acute carpal tunnel syndrome of the hand following a cat bite.

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    Sbai, Mohamed Ali; Dabloun, Slim; Benzarti, Sofien; Khechimi, Myriam; Jenzeri, Abdesselem; Maalla, Riadh

    2015-01-01

    Cat bites at the hand are common situation in emergency departments. Neglected or poorly supported, these lesions sometimes lead to serious injuries that may compromise the function of the hand. Pasteurellamultocida is the most offending germ in these lesions, despite their sensitivity to antibiotics; it can sometimes lead to deep infections involving the skin, bones and joints. Acute carpal tunnel syndrome is exceptional after cat bite. We report a case of a 56 Year old female presenting with an acute carpal tunnel syndrome associated with compartment syndrome of the right hand 6 days after a cat bite of her right thumb. The patient was treated by surgery to relieve the median nerve. Microbiology identified PasteurellaMultocida.

  2. Tarsal tunnel syndrome in patients with rheumatoid arthritis ...

    African Journals Online (AJOL)

    Ibrahim Khalil Ibrahim

    2013-01-10

    Jan 10, 2013 ... 'loss of substance' and evolve into a partial or complete tendon tear. Where .... Name, age, sex, occupation, marital status, menstrual history, and parity. 4.2. ... causing reproduction of symptoms,18,19 and ankle inversion.

  3. Isolated dorsal dislocation of the tarsal naviculum

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    Kaziz Hamdi

    2015-01-01

    Full Text Available Isolated dislocation of the tarsal naviculum is an unusual injury, scarcely reported in the literature. The naviculum is surrounded by the rigid bony and ligamentous support hence fracture dislocation is more common than isolated dislocation. The mechanism and treatment options remain unclear. In this case report, we describe a 31 year old man who sustained an isolated dorsal dislocation of the left tarsal naviculum, without fracture, when he was involved in a motor vehicle collision. The reported mechanism of the dislocation is a hyper plantar flexion force applied to the midfoot, resulting in a transient disruption of the ligamentous support of the naviculum bone, with dorsal displacement of the bone. The patient was treated with open reduction and Krischner-wire fixation of the navicular after the failure of closed reduction. The wires were removed after 6 weeks postoperatively. Physiotherapy for stiffness and midfoot pain was recommended for 2 months. At 6 months postoperatively, limping, midfoot pain and weakness were reported, no X-ray abnormalities were found. The patient returned to his obvious activities with a normal range of motion.

  4. The bone scan in tarsal coalition: a case report

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    De Lima, R.T. [Department of Radiology, Division of Nuclear Medicine, Harbor-UCLA Medical Center, Torrance, CA (United States); Mishkin, F.S. [Department of Radiology, Division of Nuclear Medicine, Harbor-UCLA Medical Center, Torrance, CA (United States)

    1996-10-01

    Tarsal coalition is abnormal fusion of two or more tarsal bones. The union may be fibrous, cartilaginous, or osseous and can be congenital or acquired in response to infection, articular disorders, trauma, or surgery. We report a case of fibrous talocalcaneal coalition in a 15-year-old boy in whom bone scintigraphy employing pinhole lateral views confirmed the clinical diagnosis when plain radiographs showed minimal changes and computed tomography was equivocal. The diagnosis of symptomatic tarsal coalition is important in that it is a common remediable cause of peroneal spastic flat foot, a frequently encountered condition. Scintigraphy provides important information about the presence and localization of this condition. (orig.). With 3 figs.

  5. [Leukoplakia of the lower tarsal conjunctiva].

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    Dierks, P; Wiegand, W

    2012-10-01

    The case of a 73-year-old woman with a perforated corneal ulcer in the remaining eye with migrating endophthalmitis is presented. In addition, the affected eye had non-abradable whitish coating (leukoplakia) on the tarsal conjunctiva. The cause of leukoplakia was initially histologically diagnosed after an incisional biopsy as focal invasive sebaceous carcinoma with pagetoid growth. After exenteration of the orbit it was confirmed to be an early invasive, non-keratinizing squamous cell carcinoma (G2) of the conjunctiva, which had emerged from a spinocellular carcinoma in situ. The early histological differentiation of malignant lesions in the conjunctiva can be extremely difficult because the pathological changes in the tissue are very similar due to the cell metaplasia.

  6. Complications, effects on dialysis dose, and survival of tunneled femoral dialysis catheters in acute renal failure.

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    Klouche, Kada; Amigues, Laurent; Deleuze, Sebastien; Beraud, Jean-Jacques; Canaud, Bernard

    2007-01-01

    Availability of a functional vascular access is a mandatory prerequisite for extracorporeal renal replacement therapy in patients with acute renal failure. The femoral site of insertion commonly is chosen because it is an easy and convenient access. However, an array of complications may substantially alter the quality of treatment, and it appears that catheter-related morbidity and dysfunction are more frequent with the femoral than internal jugular site. This study is designed to evaluate the potential benefits of using soft silicone tunneled catheters ((ST)Caths) at the femoral site. Thirty patients with acute renal failure treated by intermittent hemodialysis (IHD) and/or continuous venovenous hemodiafiltration (CVVHDF) were assigned to either twin (ST)Caths or twin polyurethane nontunneled femoral catheters. Time necessary for catheter insertion, catheter-related complications, and catheter lifespan were monitored. Catheter performance during IHD and the effect of catheter type on dialysis dose were evaluated. The time necessary for (ST)Cath insertion was significantly longer. The incidence of vein thrombosis and catheter-related infection was lower, and the ratio of venous return pressure to catheter blood flow was better with an (ST)Cath. Recirculation rates were similar for both types of catheters. Whether treated by using IHD or CVVHDF, patients with an (ST)Cath benefited from a greater delivered dialysis dose. Multivariate analysis confirmed that (ST)Cath use was a determinant factor to optimize dialysis dose delivery. (ST)Cath patency was significantly longer. In patients with acute renal failure, use of an (ST)Cath minimizes catheter-related morbidity and improves dialysis efficiency compared with conventional femoral catheters.

  7. Atypical presentation of pilomatrixoma in the tarsal conjunctiva

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    Mirtha Ramirez Dittrich

    2016-06-01

    Full Text Available ABSTRACT Pilomatrixoma is a rare benign tumor, which usually affects young women in the head and neck region. The eyelid is a common site of the disease, though it is very rare in the tarsal conjunctiva.The pilomatrixoma has clinical pleomorphism, which confuses this disease with other similar conditions. The diagnosis is made by pathological examination in most cases. The treatment is surgical, performed by total excision of the lesion with clear margins and recurrence is very uncommon.We present an unusual case of probable recurrent pilomatrixoma in the left upper tarsal conjunctiva.

  8. Tarsal coalition: a blinded comparison of MRI and CT

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    Emery, K.H.; Bisset, G.S. III; Johnson, N.D.; Nunan, P.J. [Department of Radiology, Children`s Hospital Medical Center, Cincinnati, OH (United States)

    1998-08-01

    Objective. To determine how well MRI can detect tarsal coalition compared with CT, the current imaging standard. Materials and methods. Coronal and axial CT and MRI were performed within 3 weeks of each other on 40 feet in 20 consecutive patients referred with symptoms of possible tarsal coalition. Scans were read independently in blinded fashion by different imagers. Coalitions were either complete (osseous) or incomplete (non-osseous). Results were compared with available surgical data and clinical follow-up. Results. Both modalities prospectively identified 15 coalitions (9 patients) and each missed 1 calcaneonavicular coalition. Twenty-three of the remaining 24 feet were negative for coalition on both CT and MRI. An atypical incomplete talocalcaneal coalition seen on CT was not identified prospectively on MRI. Conclusion. MRI is very good for detecting tarsal coalition and has a high rate of agreement with CT, the imaging ``gold standard.`` When clinical suspicion for coalition is high, CT remains a more cost-effective diagnostic modality. If other causes for ankle pain are also entertained, MRI can be performed and provide nearly equivalent diagnostic accuracy for detecting tarsal coalition. (orig.) With 3 figs., 3 tabs., 11 refs.

  9. Detecting substrate engagement: responses of tarsal campaniform sensilla in cockroaches.

    Science.gov (United States)

    Zill, Sasha N; Keller, Bridget R; Chaudhry, Sumaiya; Duke, Elizabeth R; Neff, David; Quinn, Roger; Flannigan, Clay

    2010-06-01

    Sensory signals of contact and engagement with the substrate are important in the control and adaptation of posture and locomotion. We characterized responses of campaniform sensilla, receptors that encode forces as cuticular strains, in the tarsi (feet) of cockroaches using neurophysiological techniques and digital imaging. A campaniform sensillum on the fourth tarsal segment was readily identified by its large action potential in nerve recordings. The receptor discharged to contractions of the retractor unguis muscle, which engages the pretarsus (claws and arolium) with the substrate. We mimicked the effects of muscle contractions by applying displacements to the retractor apodeme (tendon). Sensillum firing did not occur to unopposed movements, but followed engagement of the claws with an object. Vector analysis of forces suggested that resisted muscle contractions produce counterforces that axially compress the tarsal segments. Close joint packing of tarsal segments was clearly observed following claw engagement. Physiological experiments showed that the sensillum responded vigorously to axial forces applied directly to the distal tarsus. Discharges of tarsal campaniform sensilla could effectively signal active substrate engagement when the pretarsal claws and arolium are used to grip the substrate in climbing, traversing irregular terrains or walking on inverted surfaces.

  10. Carpal and tarsal bone development is highly sensitive to three antiproliferative teratogens in mice.

    Science.gov (United States)

    Rahman, M E; Ishikawa, H; Watanabe, Y; Endo, A

    1996-01-01

    When pregnant mice were given small doses of teratogens (cytosine arabinoside, mitomycin C, or busulfan) that did not induce anomalies of any other organs, a high incidence of carpal and tarsal bone anomalies still occurred. The carpal and tarsal bones may be used as a sensitive target for teratogenicity testing.

  11. Relationship of the dorsalis pedis artery to the tarsal navicular.

    Science.gov (United States)

    Rimchala, Chakorn; Chuckpaiwong, Bavornrit

    2015-01-01

    When undertaking surgical maneuvers about the midfoot, caution must be used to avoid injury to the dorsalis pedis artery, which courses along the dorsum of the foot on the dorsolateral aspect of the tarsal navicular. In an effort to better understand the relationship of the course of the dorsalis pedis artery relative to the tarsal navicular, 128 embalmed feet (31 [48.4%] female and 33 [51.6%] male cadavers aged 15 to 91 years) were measured. The dorsalis pedis artery was dissected from its origin to its termination (i.e., the first dorsal metatarsal artery and the deep plantar perforating artery), and the distance from the medial cortex of the navicular tuberosity to the medial margin of the artery and the location of the artery as a percentage of the medial-to-lateral width of the navicular were measured. In the male cadaver specimens, the distance from the navicular tuberosity to the dorsalis pedis was 23.75 ± 3.1 mm, the width of the navicular was 37.41 ± 5.0 mm, and the location of the artery as a percentage of the width of the navicular was 64.34% ± 13.1%. In the female cadaver specimens, the distance from the navicular tuberosity to the dorsalis pedis was 22.81 ± 5.5 mm, the width of the navicular was 36.11 ± 4.0 mm, and the location of the artery as a percentage of the width of the navicular was 63.29% ± 9.9%. For the right foot specimens, the distance from the navicular tuberosity to the dorsalis pedis artery was 20.29 ± 3.3 mm, and the width of the navicular was 37.21 ± 4.4 mm. For the left foot specimens, the distance from the navicular tuberosity to the dorsalis pedis was 21.40 ± 2.5 mm, and the width of the navicular was 35.92 ± 4.4 mm. The statistical comparisons between the males and females showed no statistically significant differences. In contrast, those between the right and left feet showed significant differences in the distance from the navicular tuberosity to the dorsalis pedis artery and the location of the dorsalis pedis artery

  12. The tarsal taste of honey bees: behavioral and electrophysiological analyses

    Directory of Open Access Journals (Sweden)

    Maria Gabriela eDe Brito Sanchez

    2014-02-01

    Full Text Available Taste plays a crucial role in the life of honey bees as their survival depends on the collection and intake of nectar and pollen, and other natural products. Here we studied the tarsal taste of honey bees through a series of behavioral and electrophysiological analyses. We characterized responsiveness to various sweet, salty and bitter tastants delivered to gustatory sensilla of the fore tarsi. Behavioral experiments showed that stimulation of opposite fore tarsi with sucrose and bitter substances or water yielded different outcomes depending on the stimulation sequence. When sucrose was applied first, thereby eliciting proboscis extension, no bitter substance could induce proboscis retraction, thus suggesting that the primacy of sucrose stimulation induced a central excitatory state. When bitter substances or water were applied first, sucrose stimulation could still elicit proboscis extension but to a lower level, thus suggesting central inhibition based on contradictory gustatory input on opposite tarsi. Electrophysiological experiments showed that receptor cells in the gustatory sensilla of the tarsomeres are highly sensitive to saline solutions at low concentrations. No evidence for receptors responding specifically to sucrose or to bitter substances was found in these sensilla. Receptor cells in the gustatory sensilla of the claws are highly sensitive to sucrose. Although bees do not possess dedicated bitter-taste receptors on the tarsi, indirect bitter detection is possible because bitter tastes inhibit sucrose receptor cells of the claws when mixed with sucrose solution. By combining behavioral and electrophysiological approaches, these results provide the first integrative study on tarsal taste detection in the honey bee.

  13. The tarsal-metatarsal complex of caviomorph rodents: Anatomy and functional-adaptive analysis.

    Science.gov (United States)

    Candela, Adriana M; Muñoz, Nahuel A; García-Esponda, César M

    2017-06-01

    Caviomorph rodents represent a major adaptive radiation of Neotropical mammals. They occupy a variety of ecological niches, which is also reflected in their wide array of locomotor behaviors. It is expected that this radiation would be mirrored by an equivalent disparity of tarsal-metatarsal morphology. Here, the tarsal-metatarsal complex of Erethizontidae, Cuniculidae, Dasyproctidae, Caviidae, Chinchillidae, Octodontidae, Ctenomyidae, and Echimyidae was examined, in order to evaluate its anatomical variation and functional-adaptive relevance in relation to locomotor behaviors. A qualitative study in functional morphology and a geometric morphometric analysis were performed. We recognized two distinct tarsal-metatarsal patterns that represent the extremes of anatomical variation in the foot. The first, typically present in arboreal species, is characterized by features that facilitate movements at different levels of the tarsal-metatarsal complex. The second pattern, typically present in cursorial caviomorphs, has a set of features that act to stabilize the joints, improve the interlocking of the tarsal bones, and restrict movements to the parasagittal plane. The morphological disparity recognized in this study seems to result from specific locomotor adaptations to climb, dig, run, jump and swim, as well as phylogenetic effects within and among the groups studies. © 2017 Wiley Periodicals, Inc.

  14. Canine tarsal architecture as revealed by high-resolution computed tomography.

    Science.gov (United States)

    Galateanu, G; Apelt, D; Aizenberg, I; Saragusty, J; Hildebrandt, T B

    2013-06-01

    Central tarsal bone (CTB) fractures are well documented and are a subject of increasing importance in human, equine and canine athletes although the mechanism of these fractures in dogs is not fully understood and an extrapolation from human medicine may not be accurate. This study reports the use of high-resolution computed tomography (CT) of 91 tarsal joints from 47 dogs to generate a more detailed in situ anatomical description of the CTB architecture in order to obtain a better understanding of the pathogenesis of CTB fractures in this species. The dogs studied represented a wide range of ages, breeds and levels of habitual physical activity and the angles of the tarsal joints studied ranged between maximal flexion (16.4°) and maximal extension (159.1°). Regardless of tarsal angle, the CTB articulated with the calcaneus exclusively at the level of its plantar process (PPCTB) in all dogs. The PPCTB presented two distinct parts in all dogs, a head and a neck. The calcaneus tended to rely on the PPCTB neck during flexion and on the PPCTB head during extension. This study describes new tarsal elements for the first time, including the calcaneal articular process, the fourth tarsal bone plantar articular process and the talar plantar prominence of the CTB. Based on calcaneo-PPCTB architecture, it is postulated that the PPCTB is a keystone structure and that at least some of CTB fractures in dogs could either commence at or are induced at this level due to the impingement forces exercised by the calcaneus.

  15. On Heels and Toes: How Ants Climb with Adhesive Pads and Tarsal Friction Hair Arrays.

    Science.gov (United States)

    Endlein, Thomas; Federle, Walter

    2015-01-01

    Ants are able to climb effortlessly on vertical and inverted smooth surfaces. When climbing, their feet touch the substrate not only with their pretarsal adhesive pads but also with dense arrays of fine hairs on the ventral side of the 3rd and 4th tarsal segments. To understand what role these different attachment structures play during locomotion, we analysed leg kinematics and recorded single-leg ground reaction forces in Weaver ants (Oecophylla smaragdina) climbing vertically on a smooth glass substrate. We found that the ants engaged different attachment structures depending on whether their feet were above or below their Centre of Mass (CoM). Legs above the CoM pulled and engaged the arolia ('toes'), whereas legs below the CoM pushed with the 3rd and 4th tarsomeres ('heels') in surface contact. Legs above the CoM carried a significantly larger proportion of the body weight than legs below the CoM. Force measurements on individual ant tarsi showed that friction increased with normal load as a result of the bending and increasing side contact of the tarsal hairs. On a rough sandpaper substrate, the tarsal hairs generated higher friction forces in the pushing than in the pulling direction, whereas the reverse effect was found on the smooth substrate. When the tarsal hairs were pushed, buckling was observed for forces exceeding the shear forces found in climbing ants. Adhesion forces were small but not negligible, and higher on the smooth substrate. Our results indicate that the dense tarsal hair arrays produce friction forces when pressed against the substrate, and help the ants to push outwards during horizontal and vertical walking.

  16. Acute Effect of Topical Menthol on Chronic Pain in Slaughterhouse Workers with Carpal Tunnel Syndrome: Triple-Blind, Randomized Placebo-Controlled Trial

    Directory of Open Access Journals (Sweden)

    Emil Sundstrup

    2014-01-01

    Full Text Available Topical menthol gels are classified “topical analgesics” and are claimed to relieve minor aches and pains of the musculoskeletal system. In this study we investigate the acute effect of topical menthol on carpal tunnel syndrome (CTS. We screened 645 slaughterhouse workers and recruited 10 participants with CTS and chronic pain of the arm/hand who were randomly distributed into two groups to receive topical menthol (Biofreeze or placebo (gel with a menthol scent during the working day and 48 hours later the other treatment (crossover design. Participants rated arm/hand pain intensity during the last hour of work (scale 0–10 immediately before 1, 2, and 3 hours after application. Furthermore, global rating of change (GROC in arm/hand pain was assessed 3 hours after application. Compared with placebo, pain intensity and GROC improved more following application of topical menthol (P=0.026 and P=0.044, resp.. Pain intensity of the arm/hand decreased by −1.2 (CI 95%: −1.7 to −0.6 following topical menthol compared with placebo, corresponding to a moderate effect size of 0.63. In conclusion, topical menthol acutely reduces pain intensity during the working day in slaughterhouse workers with CTS and should be considered as an effective nonsystemic alternative to regular analgesics in the workplace management of chronic and neuropathic pain.

  17. Fetal development of ligaments around the tarsal bones with special reference to contribution of muscles.

    Science.gov (United States)

    Uchiyama, Eiichi; Kim, Ji Hyun; Abe, Hiroshi; Cho, Baik Hwan; Rodríguez-Vázquez, Jose Francisco; Murakami, Gen

    2014-04-01

    Through a histological examination of eight mid-term human fetuses (10-15 weeks) and seven late-stage fetuses (30-34 weeks), we attempted to determine how and when fetal ligaments around the tarsal bones form the regular arrangement seen in adults. Ligaments along the dorsal aspect of the tarsal bones developed early as an elongation of the perichondrium, in contrast to the late development of the plantar-sided ligaments. In contrast, a distal elongation of the tibialis posterior tendon was a limited plantar ligament in the early stage; finally, it extended from the navicular, ran obliquely to cross the dorsal side of the fibularis longus tendon, and inserted to the lateral cuneiform and fourth metatarsal. In the late stage, the adductor hallucis muscle origin provided multiple ligamentous structures along the cuneiforms and metatarsals. The tarsal sinus contained multiple fibrous bundles (possibly, the putative interosseous talocalcanean ligaments) that were derived from (1) insertion tendons of the extensor digitorus brevis muscle and (2) the fibrous sheath of the extensor digitorus longus tendon. The aponeurotic origin of the quadratus plantae muscle seemed to contribute to formation of the long plantar ligament. Therefore, tarsal ligaments appeared likely to develop from the long tendons, their fibrous sheaths and aponeuroses and intramuscular tendons of the proper foot muscles. Under in utero conditions with little or no stress from the plantar side of the foot, the muscle-associated connective tissue seems to play a crucial role in providing a regular arrangement of the ligaments in accordance with tensile stress from muscle contraction. Copyright © 2013 Wiley Periodicals, Inc.

  18. Tarsal lameness of dairy bulls housed at two artificial insemination centers: 24 cases (1975-1987).

    Science.gov (United States)

    Bargai, U; Cohen, R

    1992-10-01

    Degenerative joint disease of the tarsi was diagnosed in 20 of 24 Holstein bulls with tarsal lameness at 2 artificial insemination centers from 1975 to 1987. Each of the 2 centers housed about 100 bulls/yr. Of the 24 bulls with tarsal lameness, 22 were from the artificial insemination center designated as A, and 2 were from the center designated as B. Examination of the housing and management procedures revealed that center A had concrete floors with cuboidal-shaped yards, whereas center B had deep sand flooring, with long, narrow yards. The only other difference between the 2 centers was that center A used 1- and 2-year-old bulls as teasers for older, heavier bulls to mount, whereas center B used bulls that were at least 6 years old to withstand the stress placed on their hind limbs by the weight of bulls undergoing semen collection. Radiographic lesions of tarsi of bulls from both centers ranged from distention of the tibiotarsal joint pouch to hypertrophic degenerative osteoarthritis of the distal, intertarsal, and tarsometatarsal joints. It was concluded that the concrete flooring and the semen collecting practices were responsible for the high prevalence of tarsal lameness and degenerative joint disease of the tarsi in bulls housed at center A.

  19. Epífora e flacidez sem ectrópio: "tarsal strip" resolve sempre?

    Directory of Open Access Journals (Sweden)

    Knijnik Denis

    2006-01-01

    Full Text Available OBJETIVO: Verificar se o "tarsal strip" melhora a epífora de pacientes sem ectrópio, mas com pálpebras flácidas. MÉTODOS: Foi feito estudo retrospectivo que incluiu uma amostra composta por pacientes com pálpebras flácidas em posição normal, sem obstrução lacrimal, operados com "tarsal strip" lateral para o tratamento de epífora. Foram incluídas no estudo 14 pálpebras inferiores em 11 pacientes. RESULTADOS: Houve resolução ou melhora significativa da epífora em 10 (71,4% olhos após período de seguimento de três meses. Todas as pálpebras operadas passaram a apresentar resistência normal após a cirurgia. CONCLUSÃO: Em pacientes com epífora, pálpebras flácidas e vias lacrimais pérvias, sem ectrópio, o "tarsal strip" pode obter melhora significativa da epífora na maioria dos casos. Como todas as pálpebras operadas recuperaram sua resistência normal, pode-se supor que a ausência de melhora da epífora, em alguns casos, possa ser explicada pela presença de outros fatores causais concomitantes com a flacidez palpebral.

  20. Comparative study of the fluid viscosity in tarsal hairy attachment systems of flies and beetles.

    Science.gov (United States)

    Peisker, Henrik; Heepe, Lars; Kovalev, Alexander E; Gorb, Stanislav N

    2014-10-06

    Wet adhesive systems of insects strongly rely for their function on the formation of capillary bridges with the substrate. Studies on the chemical composition and evaporation dynamics of tarsal secretions strongly suggest a difference in chemistry of secretion in beetles and flies, both possessing hairy attachment devices. This difference is assumed to influence the viscosity of the secretion. Here, we applied a microrheological technique, based on the immersion of nanometric beads in the collected tarsal footprints, to estimate secretion viscosity in a beetle (Coccinella septempunctata) and a fly (Calliphora vicina). Both species studied possess distinct differences in viscosity, the median of which was calculated as 21.8 and 10.9 mPa s, respectively. We further present an approximate theoretical model to calculate the contact formation time of spatula-like terminal contact elements using the viscosity data of the covering fluid. The estimated contact formation time is proportional to the tarsal secretion viscosity and to the square of the contact radius of the contact element. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  1. Short tunnels.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1965-01-01

    Before dealing with the question of lighting short tunnels, it is necessary define what is meant by a tunnel and when it should be called 'short'. Confined to motorized road traffic the following is the most apt definition of a tunnel: every form of roofing-over a road section, irrespective of it le

  2. Clinical and diagnostic imaging characteristics of lateral digital flexor tendinitis within the tarsal sheath in four horses.

    Science.gov (United States)

    Davis, Weston; Caniglia, Christopher J; Lustgarten, Meghann; Blackwelder, Travis; Robertson, Ian; Redding, W Rich

    2014-01-01

    Lateral digital flexor tendonitis is a rarely reported cause of hind limb lameness in performance horses. The purpose of this retrospective study was to describe clinical and diagnostic imaging findings for a group of horses with lateral digital flexor tendinitis within the tarsal sheath. Equine cases with a diagnosis of lateral digital flexor tendonitis and magnetic resonance imaging (MRI) studies of the affected region were retrieved from North Carolina University’s medical record database. Recorded data for included horses were signalment; findings from history, physical examination, lameness examination, and all diagnostic imaging studies; treatment administered; and outcome. Four horses met inclusion criteria. Lameness was mild/moderate in severity and insidious in onset in all patients. Responses to flexion tests were variable. All horses showed positive improvement(70–90%) in lameness after tarsal sheath analgesia. Radiographic, scintigraphic, and ultrasonographic findings were inconclusive. For all horses, MRI characteristics included increased T2, PD, and STIR signal intensity within the lateral digital flexor tendon in the area of the tarsal sheath. Tarsal sheath effusion was slight in three horses, and mild/moderate in one horse. With medical treatment, two horses were sound at 6-month follow up, one horse was sound at 1-year followup, and one horse had a slight persistent lameness (grade 1/5) at 9-month followup. Findings supported the use of MRI for diagnosing lateral digital flexor tendonitis within the tarsal sheath in horses. Affected horses may have a good prognosis for return to athletic performance following appropriate medical treatment.

  3. Primary localized amyloidosis presenting as a tarsal mass: Report of two cases

    Directory of Open Access Journals (Sweden)

    Saurabh Kamal

    2012-01-01

    Full Text Available Amyloidosis and its ophthalmic manifestations are rare. The unusual presentation can result in diagnostic delay and increase ocular morbidity. Additionally, there are various predisposing conditions and systemic involvement can affect various organs. Hence, localized disease warrants a thorough clinical evaluation and laboratory investigation. We report two cases of primary localized amyloidosis presenting as a tarsal mass and ptosis. The diagnosis was established on histopathology. There were no predisposing conditions and no systemic involvement. The disease was probably related to the local immunocyte disorder.

  4. The Tarsal Bone Test: A Basic Test of Health Sciences Students' Knowledge of Lower Limb Anatomy

    Directory of Open Access Journals (Sweden)

    José Manuel Castillo-López

    2014-01-01

    Full Text Available Objectives. The aim of the present study was to design an easy-to-use tool, the tarsal bone test (TBT, to provide a snapshot of podiatry students’ basic anatomical knowledge of the bones of the lower limb. Methods. The study included 254 podiatry students from three different universities, 145 of them were first-year students and 109 were in their fourth and final years. The TBT was administered without prior notice to the participants and was to be completed in 5 minutes. Results. The results show that 97.2% of the subjects (n=247 correctly labelled all tarsal bones, while the other 2.8% (n=7 incorrectly labelled at least one bone, that was either the cuboid (7 times or the navicular (6 times. Although only one fourth-year student inaccurately identified one bone, no significant differences in the distribution of the correct and incorrect responses were found between first and fourth-year students. Conclusions. The TBT seems to be a straightforward and easy-to-apply instrument, and provides an objective view of the level of knowledge acquired at different stages of podiatry studies.

  5. Pushing versus pulling: division of labour between tarsal attachment pads in cockroaches.

    Science.gov (United States)

    Clemente, Christofer J; Federle, Walter

    2008-06-07

    Adhesive organs on the legs of arthropods and vertebrates are strongly direction dependent, making contact only when pulled towards the body but detaching when pushed away from it. Here we show that the two types of attachment pads found in cockroaches (Nauphoeta cinerea), tarsal euplantulae and pretarsal arolium, serve fundamentally different functions. Video recordings of vertical climbing revealed that euplantulae are almost exclusively engaged with the substrate when legs are pushing, whereas arolia make contact when pulling. Thus, upward-climbing cockroaches used front leg arolia and hind leg euplantulae, whereas hind leg arolia and front leg euplantulae were engaged during downward climbing. Single-leg friction force measurements showed that the arolium and euplantulae have an opposite direction dependence. Euplantulae achieved maximum friction when pushed distally, whereas arolium forces were maximal during proximal pulls. This direction dependence was not explained by the variation of shear stress but by different contact areas during pushing or pulling. The changes in contact area result from the arrangement of the flexible tarsal chain, tending to detach the arolium when pushing and to peel off euplantulae when in tension. Our results suggest that the euplantulae in cockroaches are not adhesive organs but 'friction pads', mainly providing the necessary traction during locomotion.

  6. [Surgical treatment of ptosis by resection of the superior tarsal muscle employing a cutaneous approach (author's transl)].

    Science.gov (United States)

    Morax, S

    1982-01-01

    A simple technique for resection of the superior tarsal muscle through a cutaneous approach, for the surgical treatment of ptosis, was employed in severe or moderate, congenital and acquired forms of the affection. Muller's muscle and the aponeurotic fascia are removed in a single piece, while conserving the tarsus.

  7. In vivo kinematic study of the tarsal joints complex based on fluoroscopic 3D-2D registration technique.

    Science.gov (United States)

    Chen Wang, M D; Geng, Xiang; Wang, Shaobai; Xin Ma, M D; Xu Wang, M D; Jiazhang Huang, M D; Chao Zhang, M D; Li Chen, M S; Yang, Junsheng; Wang, Kan

    2016-09-01

    The tarsal bones articulate with each other and demonstrate complicated kinematic characteristics. The in vivo motions of these tarsal joints during normal gait are still unclear. Seven healthy subjects were recruited and fourteen feet in total were tested in the current study. Three dimensional models of the tarsal bones were first created using CT scanning. Corresponding local 3D coordinate systems of each tarsal bone was subsequently established for 6DOF motion decompositions. The fluoroscopy system captured the lateral fluoroscopic images of the targeted tarsal region whilst the subject was walking. Seven key pose images during the stance phase were selected and 3D to 2D bone model registrations were performed on each image to determine joint positions. The 6DOF motions of each tarsal joint during gait were then obtained by connecting these positions together. The TNJ (talo-navicular joint) exhibited the largest ROMs (range of motion) on all rotational directions with 7.39±2.75°of dorsi/plantarflexion, 21.12±4.68°of inversion/eversion, and 16.11±4.44°of internal/external rotation. From heel strike to midstance, the TNJ, STJ (subtalar joint), and CCJ (calcaneao-cuboid joint) were associated with 5.97°, 5.04°, and 3.93°of dorsiflexion; 15.46°, 8.21°, and 5.82°of eversion; and 9.75°, 7.6°, and 4.99°of external rotation, respectively. Likewise, from midstance to heel off, the TNJ, STJ, and CCJ were associated with 6.39, 6.19°, and 4.47°of plantarflexion; 18.57°, 11.86°, and 6.32°of inversion and 13.95°, 9.66°, and 7.58°of internal rotation, respectively. In conclusion, among the tarsal joints, the TNJ exhibited the greatest rotational mobility. Synchronous and homodromous rotational motions were detected for TNJ, STJ, and CCJ during the stance phase.

  8. Comparison of heparin to citrate as a catheter locking solution for non-tunneled central venous hemodialysis catheters in patients requiring renal replacement therapy for acute renal failure (VERROU-REA study): study protocol for a randomized controlled trial.

    Science.gov (United States)

    Bruyère, Rémi; Soudry-Faure, Agnès; Capellier, Gilles; Binquet, Christine; Nadji, Abdelouaid; Torner, Stephane; Blasco, Gilles; Yannaraki, Maria; Barbar, Saber Davide; Quenot, Jean-Pierre

    2014-11-19

    The incidence of acute kidney injury (AKI) is estimated at 10 to 20% in patients admitted to intensive care units (ICU) and often requires renal replacement therapy (RRT). ICU mortality in AKI patients can exceed 50%. Venous catheters are the preferred vascular access method for AKI patients requiring RRT, but carry a risk of catheter thrombosis or infection. Catheter lock solutions are commonly used to prevent such complications. Heparin and citrate locks are both widely used for tunneled, long-term catheters, but few studies have compared citrate versus heparin for patients with short-term, non-tunneled catheters. We aim to compare citrate 4% catheter lock solution versus heparin in terms of event-free survival of the first non-tunneled hemodialysis catheter inserted in ICU patients with AKI requiring RRT. Secondary objectives are the rate of fibrinolysis, incidence of catheter thrombosis and catheter-related infection per 1,000 catheter days, length of stay in ICU and in-hospital and 28-day mortality. The VERROU-REA study is a randomized, prospective, multicenter, double-blind, parallel-group, controlled superiority study carried out in the medical, surgical and nephrological ICUs of two large university hospitals in eastern France. A catheter lock solution composed of trisodium citrate at 4% will be compared to unfractionated heparin at a concentration of 5,000 IU/mL. All consecutive adult patients with AKI requiring extracorporeal RRT, and in whom a first non-tunneled catheter is to be inserted by the jugular or femoral approach, will be eligible. Catheters inserted by the subclavian approach, patients with acute liver failure, thrombopenia or contraindication to systemic anticoagulation will be excluded. Patients will be followed up daily in accordance with standard practices for RRT until death or discharge. Data is scarce regarding the use of non-tunneled catheters in the ICU setting in patients with AKI. This study will provide an evidence base for

  9. External fixation to correct tarsal-metatarsal fracture in rock pigeon (Columba livia

    Directory of Open Access Journals (Sweden)

    Leandro Almeida Rui

    Full Text Available ABSTRACT Orthopedic conditions, such as bone fractures, are very common in avian medicine. External fixators have been considered the gold standard for birds, since they allow early movement of the limbs and minimal invasive surgery. Fractures in several bones have been successfully treated in pigeons. However, to the best of our knowledge, this case represents the first report of successful surgical repair of tarsal-metatarsal fracture in rock pigeon. External fixator was made with four 24G catheters, being inserted manually proximal and distal to the fracture and connected with polymerizable acrylic. Radiographic consolidation of fracture was observed 60 days post-surgery and anti-inflammatory and antibiotic protocols were successful on avoiding pain and infection during surgery and bone healing.

  10. Slab fractures of the third tarsal bone: Minimally invasive repair using a single 3.5 mm cortex screw placed in lag fashion in 17 Thoroughbred racehorses.

    Science.gov (United States)

    Barker, W H J; Wright, I M

    2017-03-01

    A technique for minimally invasive repair of slab fractures of the third tarsal bone has not previously been reported. Results of third tarsal bone slab fracture repair in Thoroughbred racehorses are lacking. To report the outcomes of repair of uniplanar frontal slab factures of the third tarsal bone using a single 3.5 mm cortex screw in lag fashion. Retrospective case series. Case records of horses that had undergone this procedure were reviewed. Seventeen horses underwent surgery. Eighteen percent of cases had wedge shaped third tarsal bones. A point midway between the long and lateral digital extensor tendons and centrodistal and tarsometatarsal joints created a suitable entry site for implants. The fracture location, configuration and curvature of the third tarsal bone and associated joints requires a dorsolateral proximal-plantaromedial distal trajectory for the screw, which was determined by preplaced needles. There were no complications and fractures healed in all cases at 4-6 months post surgery. Seventy-nine percent of horses returned to racing and, at the time of reporting, 3 are in post operative rehabilitation programmes. The technique reported provides a safe, appropriate and repeatable means of repairing slab fractures of the third tarsal bone. Surgical repair is a viable alternative to conservative management. © 2016 EVJ Ltd.

  11. Comparison of intra-articular drilling and diode laser treatment for arthrodesis of the distal tarsal joints in normal horses.

    Science.gov (United States)

    Scruton, C; Baxter, G M; Cross, M W; Frisbie, D D

    2005-01-01

    Anecdotal reports suggest that laser-facilitated arthrodesis of the distal tarsal joints improves the prognosis compared with intra-articular drilling but no objective comparisons have been performed. To evaluate intra-articular drilling and laser-facilitated arthrodesis using in situ and in vivo techniques. Fourteen cadaver limbs were evaluated in situ for chondrocyte viability after both surgical techniques. In vivo, one randomly selected limb was subjected to laser-facilitated arthrodesis and the other underwent intra-articular drilling in 6 normal horses. Clinical examinations were performed at 1, 3 and 5 months. Two horses were subjected to euthanasia at 1, 3 and 5 months. Significantly more chondrocyte death was observed with laser-facilitated arthrodesis compared to drilling, but the overall degree suggested only a focal effect. In vivo, both groups demonstrated minimal post operative morbidity. There was more evidence of arthrodesis seen at all time points with intra-articular drilling. This study demonstrated that changes associated with ultimate arthrodesis occur earlier after intra-articular drilling of the distal tarsal joints than laser-facilitated arthrodesis, although clinically affected horses may respond differently. Intra-articular drilling may provide earlier arthrodesis of the distal tarsal joints, but not necessarily a better long-term result.

  12. Central tarsal bone fractures in horses not used for racing: Computed tomographic configuration and long-term outcome of lag screw fixation.

    Science.gov (United States)

    Gunst, S; Del Chicca, F; Fürst, A E; Kuemmerle, J M

    2016-09-01

    There are no reports on the configuration of equine central tarsal bone fractures based on cross-sectional imaging and clinical and radiographic long-term outcome after internal fixation. To report clinical, radiographic and computed tomographic findings of equine central tarsal bone fractures and to evaluate the long-term outcome of internal fixation. Retrospective case series. All horses diagnosed with a central tarsal bone fracture at our institution in 2009-2013 were included. Computed tomography and internal fixation using lag screw technique was performed in all patients. Medical records and diagnostic images were reviewed retrospectively. A clinical and radiographic follow-up examination was performed at least 1 year post operatively. A central tarsal bone fracture was diagnosed in 6 horses. Five were Warmbloods used for showjumping and one was a Quarter Horse used for reining. All horses had sagittal slab fractures that began dorsally, ran in a plantar or plantaromedial direction and exited the plantar cortex at the plantar or plantaromedial indentation of the central tarsal bone. Marked sclerosis of the central tarsal bone was diagnosed in all patients. At long-term follow-up, 5/6 horses were sound and used as intended although mild osteophyte formation at the distal intertarsal joint was commonly observed. Central tarsal bone fractures in nonracehorses had a distinct configuration but radiographically subtle additional fracture lines can occur. A chronic stress related aetiology seems likely. Internal fixation of these fractures based on an accurate diagnosis of the individual fracture configuration resulted in a very good prognosis. © 2015 EVJ Ltd.

  13. Oldest known euarchontan tarsals and affinities of Paleocene Purgatorius to Primates.

    Science.gov (United States)

    Chester, Stephen G B; Bloch, Jonathan I; Boyer, Doug M; Clemens, William A

    2015-02-03

    Earliest Paleocene Purgatorius often is regarded as the geologically oldest primate, but it has been known only from fossilized dentitions since it was first described half a century ago. The dentition of Purgatorius is more primitive than those of all known living and fossil primates, leading some researchers to suggest that it lies near the ancestry of all other primates; however, others have questioned its affinities to primates or even to placental mammals. Here we report the first (to our knowledge) nondental remains (tarsal bones) attributed to Purgatorius from the same earliest Paleocene deposits that have yielded numerous fossil dentitions of this poorly known mammal. Three independent phylogenetic analyses that incorporate new data from these fossils support primate affinities of Purgatorius among euarchontan mammals (primates, treeshrews, and colugos). Astragali and calcanei attributed to Purgatorius indicate a mobile ankle typical of arboreal euarchontan mammals generally and of Paleocene and Eocene plesiadapiforms specifically and provide the earliest fossil evidence of arboreality in primates and other euarchontan mammals. Postcranial specializations for arboreality in the earliest primates likely played a key role in the evolutionary success of this mammalian radiation in the Paleocene.

  14. Decaleside: a new class of natural insecticide targeting tarsal gustatory sites.

    Science.gov (United States)

    Rajashekar, Yallappa; Rao, Lingamallu J M; Shivanandappa, Thimmappa

    2012-10-01

    Natural sources for novel insecticide molecules hold promise in view of their eco-friendly nature, selectivity, and mammalian safety. Recent progress in understanding the biology of insect olfaction and taste offers new strategies for developing selective pest control agents. We have isolated two natural insecticidal molecules from edible roots of Decalepis hamiltonii named Decalesides I and II, which are novel trisaccharides, highly toxic to household insect pests and stored-product insects. We have experimentally shown that insecticidal activity requires contact with tarsi on the legs but is not toxic orally. The insecticidal activity of molecules is lost by hydrolysis, and various sugars modify toxic response, showing that the insecticidal activity is via gustatory sites on the tarsi. Selective toxicity to insects by virtue of their gustatory site of action and the mammalian safety of the new insecticides is inherent in their chemical structure with 1-4 or 1-1 α linkage that is easily hydrolyzed by digestive enzymes of mammals. Decalesides represent a new chemical class of natural insecticides with a unique mode of action targeting tarsal chemosensory/gustatory system of insects.

  15. Evaporation dynamics of tarsal liquid footprints in flies (Calliphora vicina)and beetles (Coccinella septempunctata).

    Science.gov (United States)

    Peisker, Henrik; Gorb, Stanislav N

    2012-04-15

    Insect tarsal adhesive structures secrete a thin layer of fluid into the contact area. It was previously reported that the presence of this fluid significantly increases adhesion on various substrata. Previous data obtained from representatives of different insect groups suggest a difference not only in the chemical composition of the fluid, but also in its physical properties. In the present study, we have measured for the first time changes in the droplet geometry over time and the evaporation rate of the fluid in flies (Calliphora vicina) and beetles (Coccinella septempunctata) by the use of atomic force microscopy. Flattened droplets of the beetle had lower evaporation rates than hemispherical footprints of the fly. Within 1 h, the droplet volume reduced to 21% of the initial volume for the fly, and to 65% for the beetle, suggesting a larger fraction of volatile compounds in the fly fluid. It was revealed that drop geometry changes significantly during evaporation and shows pinning effects for the fly footprints due to an assumed self-organizing oil layer on top of the water fraction of the micro-emulsion. The data obtained suggest that the adhesion strength in capillarity-based switchable adhesive systems must be time-dependent because of the specific evaporation rate of the adhesive fluid. These results are important for our understanding of the functional mechanism of insect adhesive systems and also for biomimetics of artificial capillarity-based adhesive systems.

  16. Decaleside: a new class of natural insecticide targeting tarsal gustatory sites

    Science.gov (United States)

    Rajashekar, Yallappa; Rao, Lingamallu J. M.; Shivanandappa, Thimmappa

    2012-10-01

    Natural sources for novel insecticide molecules hold promise in view of their eco-friendly nature, selectivity, and mammalian safety. Recent progress in understanding the biology of insect olfaction and taste offers new strategies for developing selective pest control agents. We have isolated two natural insecticidal molecules from edible roots of Decalepis hamiltonii named Decalesides I and II, which are novel trisaccharides, highly toxic to household insect pests and stored-product insects. We have experimentally shown that insecticidal activity requires contact with tarsi on the legs but is not toxic orally. The insecticidal activity of molecules is lost by hydrolysis, and various sugars modify toxic response, showing that the insecticidal activity is via gustatory sites on the tarsi. Selective toxicity to insects by virtue of their gustatory site of action and the mammalian safety of the new insecticides is inherent in their chemical structure with 1-4 or 1-1 α linkage that is easily hydrolyzed by digestive enzymes of mammals. Decalesides represent a new chemical class of natural insecticides with a unique mode of action targeting tarsal chemosensory/gustatory system of insects.

  17. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... arm. Just a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ligament and ... difficult. Often, the cause is having a smaller carpal tunnel than other people do. Other causes include ...

  18. Tarsal Structure and Identification of Tarsal Secretions of Both Sexes of Ambrostoma quadriimpressum%榆紫叶甲雌雄两性跗垫结构及分泌物成分鉴定

    Institute of Scientific and Technical Information of China (English)

    田海娇; 肖丹; 胡基华; 孙凡

    2012-01-01

    The sexual dimorphism in tarsal adhesive setae in both female and male Ambrostoma quadriimpressum Motschulsky was observed using scanning electron microscope ( SEM) . The three types of setae on tarsi are lanceolate setae with a flattened tapered terminal part, spatula-shaped setae, and setae with a discoidal terminal. The tarsi of both female and male A. quadriimpressum are covered with lanceolate and spatula-shaped setae, while discoidal setae only distribute on the male tarsi. There is no significant difference in principal components of tarsal secretions extracted by hexane between male and female A. qiiadriimpressum. The tarsal secretions of A. quadriimpressum consist of straight-chain hydrocarbon (C14-C36) and branched-chain hydrocarbon with 1-3 methyl identified by GC-MS.%通过扫描电镜观察到榆紫叶甲(Ambrostoma quadriimpressum Motschulsky)雌雄两性跗垫具有性二型现象.跗垫上着生有矛状、铲状和盘状3种类型刚毛,其中矛形刚毛和铲形刚毛在雌雄两性的跗垫上都有分布,盘形刚毛只分布在雄性跗垫上.用正己烷对雌雄两性的跗垫分泌物进行提取,经气相色谱(GC)分离后,分析发现雌雄两性的跗垫分泌物在组分上没有明显差异.经气质(GC-MS)鉴定跗垫分泌物由一系列的14~ 36个碳的直链烷烃和带l~3个甲基的支链烷烃组成.

  19. Recurrence of trachomatous trichiasis 17 years after bilamellar tarsal rotation procedure.

    Science.gov (United States)

    Khandekar, Rajiv; Al-Hadrami, Khalfan; Sarvanan, Natarajan; Al Harby, Saleh; Mohammed, Ali Jaffer

    2006-06-01

    In 1989, World Health Organization consultant operated on trachomatous trichiasis (TT) cases in Dhakhiliya region of Oman. We evaluated their current ocular status. This was an historic cohort study. This study was conducted in an in-house setting. Ninety-one patients with TT who underwent operation by the bilamellar tarsal rotation procedure (BTR) were our study population. Their preoperative, operative, and immediate postoperative data were retrieved from the register. Staff members located and visited these patients. They examined the eyes and determined their visual, TT, and corneal status. They interviewed participants with a close-ended questionnaire to assess the quality of life and satisfaction for the TT services that were offered. Sixty-three patients could be followed. Among 72 eyes that had undergone operation 17 years earlier, the recurrence rate was 47.2% (95% CI, 35.7-58.8). In 21 unoperated eyes (55%), TT was noted. The association of TT recurrence to age, gender, type of TT, conjunctivitis, and active trachoma was tested. The BTR for minor trichiasis was the risk factor for recurrence of TT (adjusted odds ratio, 3.9; 95% CI, 1.4-10.8). The high recurrence rate of TT, 17 years after BTR surgery and high rates of TT in eyes that did not undergo surgical procedure earlier suggest that the causes of high recurrence should be identified and addressed. The ongoing pathologic condition of scarring of upper lids of both operated and unoperated eyes could be responsible for lid status after 17 years of BTR surgeries. High percentage of refusals because of long-term high recurrence could pose a challenge to reach the "elimination of blinding trachoma" by 2020.

  20. Dinámicas complejas en el desarrollo del primer segmento tarsal de Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Juan Nicolas Malagon

    2016-09-01

    Full Text Available La interacción de grupos de genes, proteínas, y células es necesaria para el desarrollo de un organismo multicelular. Por tal motivo, la teoría de la complejidad puede ser una herramienta indispensable para entender cómo diversos procesos embriológicos y evolutivos suceden. Sin embargo, en la mayoría de los programas de investigación estas áreas permanecen aisladas. En un esfuerzo por crear un punto de integración entre el Evo-Devo y las ciencias de la complejidad, en este documento propongo que las dinámicas celulares de epitelios pueden tener comportamientos que se asemejan a los encontrados en sistemas complejos. Dichas dinámicas celulares, además de regular la densidad celular de los epitelios, pueden conferir alta evolucionabilidad a estos tejidos. Para lograr este objetivo, utilizo como sistema el desarrollo del primer segmento tarsal de las patas anteriores de Drosophila melanogaster. Primero doy un ejemplo en el cual dinámicas aleatorias a nivel celular pueden generar la emergencia de patrones organizados a nivel del tejido. En seguida muestro como la modificación de características morfológicas del epitelio puede generar dinámicas celulares altamente organizadas o por el contrario aleatorios. Como resultado, planteó que el desarrollo de los epitelios muestra rasgos de comportamientos complejos y propone que la retro-alimentación entre tensión mecánica y procesos celulares son básicos para entender cómo se desarrollan y evolucionan los organismos multicelulares. Estos estudios ponen en evidencia las bases mecánicas de procesos complejos que conectan diversos niveles de organización.

  1. DINÁMICAS COMPLEJAS EN EL DESARROLLO DEL PRIMER SEGMENTO TARSAL DE Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Juan Nicolás MALAGON

    2016-01-01

    Full Text Available La interacción de grupos de genes, proteínas, y células es necesaria para el desarrollo de un organismo multicelular. Por tal motivo, la teoría de la complejidad puede ser una herramienta indispensable para entender cómo diversos procesos embriológicos y evolutivos suceden. Sin embargo, en la mayoría de los programas de investigación estas áreas permanecen aisladas. En un esfuerzo por crear un punto de integración entre el Evo-Devo y las ciencias de la complejidad, en este documento propongo que las dinámicas celulares de epitelios pueden tener comportamientos que se asemejan a los encontrados en sistemas complejos. Dichas dinámicas celulares, además de regular la densidad celular de los epitelios, pueden conferir alta evolucionabilidad a estos tejidos. Para lograr este objetivo, utilizo como sistema el desarrollo del primer segmento tarsal de las patas anteriores de Drosophila melanogaster. Primero doy un ejemplo en el cual dinámicas aleatorias a nivel celular pueden generar la emergencia de patrones organizados a nivel del tejido. En seguida muestro como la modificación de características morfológicas del epitelio puede generar dinámicas celulares altamente organizadas o por el contrario aleatorios. Como resultado, planteó que el desarrollo de los epitelios muestra rasgos de comportamientos complejos y propone que la retro-alimentación entre tensión mecánica y procesos celulares son básicos para entender cómo se desarrollan y evolucionan los organismos multicelulares. Estos estudios ponen en evidencia las bases mecánicas de procesos complejos que conectan diversos niveles de organización.

  2. Tarsal Bone Dysplasia in Clubfoot as Measured by Ultrasonography: Can It be Used as a Prognostic Indicator in Congenital Idiopathic Clubfoot? A Prospective Observational Study.

    Science.gov (United States)

    Chandrakanth, Udayakumar; Sudesh, Pebam; Gopinathan, NirmalRaj; Prakash, Mahesh; Goni, Vijay G

    2016-01-01

    Congenital talipes equinovarus (CTEV )/clubfoot is the most common congenital orthopedic condition. The success rate of Ponseti casting in the hands of the legend himself is not 100%. The prediction of difficult to correct foot and recurrences still remains a mystery to be solved. We all know that tarsal bones are dysplastic in clubfoot and considering it; we hypothesize that the amount of tarsal dysplasia can predict management duration and outcome. In literature we were not able to find studies that satisfactorily quantify the amount of tarsal dysplasia. Hence, it was considered worthwhile to quantify the amount of dysplasia in tarsal bone and to correlate these parameters with the duration and outcome of treatment by conventional method. A total of 25 infants with unilateral idiopathic clubfoot that have not taken any previous treatment were included in the study. An initial ultrasonography was done before start of treatment in 3 standard planes to measure the maximum length of 3 tarsal bones (talus, calcaneus, and navicular). Ponseti method of treatment was used; pirani scoring was done at each OPD (out patient department) visit. Number of casts required for complete correction and need for any surgical intervention were taken as the outcome parameters. We found that there is a significant correlation between number of casts required and the dysplasia of talus (α error=0.05). We also found a significant negative correlation between relative dysplasia of talus and number of casts required (r=-0.629 sig=0.001, r=-0.552 sig=0.004). Tarsal bone dysplasia as quantified by using ultrasonography can be used as a prognostic indicator in congenital idiopathic clubfoot. Although promising the method needs further studies and can be more useful after long-term follow-up where recurrences if any can be documented. Level II.

  3. New results on sexual differences in tarsal adhesive setae of Diabrotica virgifera virgifera LeConte (Coleoptera, Chrysomelidae, Galerucinae

    Directory of Open Access Journals (Sweden)

    Kai Gloyna

    2014-12-01

    Full Text Available Previous light microscopy studies revealed a hairless patch on the feet of male Diabrotica virgifera virgifera. However, in related species of chrysomelid beetles the males have special adhesive setae with discoid terminals, which adhere to the elytra of females during copulation. In the present study, we examined the pretarsi of D. virgifera virgifera at a high magnification using scanning electron microscopy. The distinct sexual tarsal dimorphism in this species is confirmed. However, our results do not support the presence of a hairless patch on the feet of males, but a field of densely-packed male-specific adhesive setae with discoid terminals.

  4. Imaging findings of tarsal chondroblastoma%跗骨成软骨细胞瘤的影像表现

    Institute of Scientific and Technical Information of China (English)

    张泽坤; 吴文娟; 李玉清; 张伟; 高静; 孙锋; 王冬梅; 丁建平; 王泽静

    2010-01-01

    目的 探讨跗骨成软骨细胞瘤的影像表现.方法 回顾分析经病理证实的134例成软骨细胞瘤的部位分布情况,对其中11例跗骨成软骨细胞瘤的X线和5例CT表现进行分析.结果 11例跗骨成软骨细胞瘤患者中,病变位于距骨6例、跟骨3例、足舟骨2例.距骨体后部及跟骨后结节为好发部位,X线表现以膨胀性骨质破坏为主(10/11),局部边缘轻度硬化(11/11),骨嵴常见(9/11),关节面破坏常见(7/11),可见斑点状钙化(6/11);CT对关节面破坏(5/5)、小的骨嵴(5/5)以及细小钙化(2/5)的显示更明显.结论 距骨、跟骨是跗骨成软骨细胞瘤好发部位,影像表现具有一定特点,但应结合其发病部位与其他疾病鉴别.%Objective To analysis the imaging features of the chondroblastoma in the tarsal bone. Methods The locations of 134 cases of pathologically confirmed chondroblastoma were retrospectively analyzed. Eleven of them were in tarsal bones and their X-ray and CT findings were analyzed. Results Of the 11 cases of tarsal chondroblastoma, 6 were in talus, 3 were in calcaneus and 2 cases were in navicular bones. They were examined by the X-ray and 5 cases had additional CT scans. The common locations were the posterior portion of the talus and calcaneus. The X-ray findings included expansive destruction (10/11), mild osteosclerosis (11/11), bone ridge (9/11), articular facet destruction (7/11) and spot or patching calcification(6/11). The imaging findings of CT included articular facets destruction (5/5), bone ridge (5/5) and spot or patching calcification (2/5). Conclusion The talus and the calcaneus are the frequently involved location of tarsal chondroblastoma. Its X-ray and CT findings are characteristic but not exclusive.

  5. Electron tunnel sensor technology

    Science.gov (United States)

    Waltman, S. B.; Kaiser, W. J.

    1989-01-01

    The recent development of Scanning Tunneling Microscopy technology allows the application of electron tunneling to position detectors for the first time. The vacuum tunnel junction is one of the most sensitive position detection mechanisms available. It is also compact, simple, and requires little power. A prototype accelerometer based on electron tunneling, and other sensor applications of this promising new technology are described.

  6. Subtalar Joint Distraction Arthrodesis to Correct Calcaneal Valgus in Pediatric Patients with Tarsal Coalition: A Case Series.

    Science.gov (United States)

    Schwartz, Jaclyn M; Kihm, Carl A; Camasta, Craig A

    2015-01-01

    Subtalar joint middle facet coalitions commonly present in children who have a painful, rigid, pes planovalgus foot type. The middle facet coalition allows rearfoot forces to be distributed medially through the coalition, and this can result in arthritis or lateral tarsal wedging. The senior author has used a wedged bone graft distraction subtalar joint arthrodesis to correct calcaneal valgus and restore the talar height in these patients. The tight, press-fit nature of the tricortical iliac crest allograft provides stability and can negate the need for internal fixation. We retrospectively reviewed 9 pediatric subtalar joint distraction arthrodesis procedures performed on 8 patients during a 6-year period. All patients began weightbearing at 6 weeks after surgery. All patients had osseous union, and no complications developed that required a second surgery. The clinical outcomes, assessed at a mean of 25.5 (range, 6.3 to 75.8) months postoperatively, were satisfactory. The mean American Orthopaedic Foot and Ankle Society score was 90.1 (range, 79 to 94), on a 94-point scale. The wedged distraction arthrodesis technique has not been previously described for correction of pediatric patients with lateral tarsal wedging, but it is an effective option and yields successful outcomes. Copyright © 2015 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  7. Fermions Tunneling from Plebanski-Demianski Black Holes

    CERN Document Server

    Sharif, M

    2013-01-01

    Hawking radiation spectrum via fermions tunneling is investigated through horizon radii of Pleba$\\acute{\\textmd{n}}$ski-Demia$\\acute{\\textmd{n}}$ski family of black holes. To this end, we determine the tunneling probabilities for outgoing and incoming charged fermion particles and obtain their corresponding Hawking temperatures. The graphical behavior of Hawking temperatures and horizon radii (cosmological and event horizons) is also studied. We find consistent results with those already available in literature.

  8. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  9. Transonic Dynamics Tunnel (TDT)

    Data.gov (United States)

    Federal Laboratory Consortium — The Transonic Dynamics Tunnel (TDT) is a continuous flow wind-tunnel facility capable of speeds up to Mach 1.2 at stagnation pressures up to one atmosphere. The TDT...

  10. Road and Railroad Tunnels

    Data.gov (United States)

    Department of Homeland Security — Tunnels in the United States According to the HSIP Tiger Team Report, a tunnel is defined as a linear underground passageway open at both ends. This dataset is based...

  11. Quantum theory of tunneling

    CERN Document Server

    Razavy, Mohsen

    2014-01-01

    In this revised and expanded edition, in addition to a comprehensible introduction to the theoretical foundations of quantum tunneling based on different methods of formulating and solving tunneling problems, different semiclassical approximations for multidimensional systems are presented. Particular attention is given to the tunneling of composite systems, with examples taken from molecular tunneling and also from nuclear reactions. The interesting and puzzling features of tunneling times are given extensive coverage, and the possibility of measurement of these times with quantum clocks are critically examined. In addition by considering the analogy between evanescent waves in waveguides and in quantum tunneling, the times related to electromagnetic wave propagation have been used to explain certain aspects of quantum tunneling times. These topics are treated in both non-relativistic as well as relativistic regimes. Finally, a large number of examples of tunneling in atomic, molecular, condensed matter and ...

  12. Hypersonic Tunnel Facility (HTF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Hypersonic Tunnel Facility (HTF) is a blow-down, non-vitiated (clean air) free-jet wind tunnel capable of testing large-scale, propulsion systems at Mach 5, 6,...

  13. The Tunnels of Samos

    Science.gov (United States)

    Apostol, Tom M. (Editor)

    1995-01-01

    This 'Project Mathematics' series video from CalTech presents the tunnel of Samos, a famous underground aquaduct tunnel located near the capital of Pithagorion (named after the famed Greek mathematician, Pythagoras, who lived there), on one of the Greek islands. This tunnel was constructed around 600 BC by King Samos and was built under a nearby mountain. Through film footage and computer animation, the mathematical principles and concepts of why and how this aquaduct tunnel was built are explained.

  14. Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities

    Directory of Open Access Journals (Sweden)

    CJ Ley

    2014-03-01

    Full Text Available Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC, articular calcified cartilage (ACC, subchondral bone (SCB and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

  15. Osteochondral lesions in distal tarsal joints of Icelandic horses reveal strong associations between hyaline and calcified cartilage abnormalities.

    Science.gov (United States)

    Ley, C J; Ekman, S; Hansson, K; Björnsdóttir, S; Boyde, A

    2014-03-25

    Osteochondral lesions in the joints of the distal tarsal region of young Icelandic horses provide a natural model for the early stages of osteoarthritis (OA) in low-motion joints. We describe and characterise mineralised and non-mineralised osteochondral lesions in left distal tarsal region joint specimens from twenty-two 30 ±1 month-old Icelandic horses. Combinations of confocal scanning light microscopy, backscattered electron scanning electron microscopy (including, importantly, iodine staining) and three-dimensional microcomputed tomography were used on specimens obtained with guidance from clinical imaging. Lesion-types were described and classified into groups according to morphological features. Their locations in the hyaline articular cartilage (HAC), articular calcified cartilage (ACC), subchondral bone (SCB) and the joint margin tissues were identified and their frequency in the joints recorded. Associations and correlations between lesion-types were investigated for centrodistal joints only. In centrodistal joints the lesion-types HAC chondrocyte loss, HAC fibrillation, HAC central chondrocyte clusters, ACC arrest and ACC advance had significant associations and strong correlations. These lesion-types had moderate to high frequency in centrodistal joints but low frequencies in tarsometatarsal and talocalcaneal-centroquartal joints. Joint margin lesion-types had no significant associations with other lesion-types in the centrodistal joints but high frequency in both the centrodistal and tarsometatarsal joints. The frequency of SCB lesion-types in all joints was low. Hypermineralised infill phase lesion-types were detected. Our results emphasise close associations between HAC and ACC lesions in equine centrodistal joints and the importance of ACC lesions in the development of OA in low-motion compression-loaded equine joints.

  16. Acute effect of topical menthol on chronic pain in slaughterhouse workers with carpal tunnel syndrome: triple-blind, randomized placebo-controlled trial

    DEFF Research Database (Denmark)

    Sundstrup, Emil; Jakobsen, Markus Due; Brandt, Mikkel;

    2014-01-01

    participants with CTS and chronic pain of the arm/hand who were randomly distributed into two groups to receive topical menthol (Biofreeze) or placebo (gel with a menthol scent) during the working day and 48 hours later the other treatment (crossover design). Participants rated arm/hand pain intensity during...... the last hour of work (scale 0-10) immediately before 1, 2, and 3 hours after application. Furthermore, global rating of change (GROC) in arm/hand pain was assessed 3 hours after application. Compared with placebo, pain intensity and GROC improved more following application of topical menthol (P = 0.......026 and P = 0.044, resp.). Pain intensity of the arm/hand decreased by -1.2 (CI 95%: -1.7 to -0.6) following topical menthol compared with placebo, corresponding to a moderate effect size of 0.63. In conclusion, topical menthol acutely reduces pain intensity during the working day in slaughterhouse workers...

  17. Magnetic tunnel junctions (MTJs)

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    We review the giant tunnel magnetoresistance (TMR) in ferromagnetic-insulator-ferromagnetic junctions discovered in recent years, which is the magnetoresistance (MR) associated with the spin-dependent tunneling between two ferromagnetic metal films separated by an insulating thin tunnel barrier. The theoretical and experimental results including junction conductance, magnetoresistance and their temperature and bias dependences are described.

  18. Proton tunneling in solids

    Energy Technology Data Exchange (ETDEWEB)

    Kondo, J.

    1998-10-01

    The tunneling rate of the proton and its isotopes between interstitial sites in solids is studied theoretically. The phonons and/or the electrons in the solid have two effects on the tunneling phenomenon. First, they suppress the transfer integral between two neighbouring states. Second, they give rise to a finite lifetime of the proton state. Usually the second effect is large and the tunneling probability per unit time (tunneling rate) can be defined. In some cases, however, a coherent tunneling is expected and actually observed. (author)

  19. Resonance Enhanced Tunneling

    CERN Document Server

    Matsumoto, S; Matsumoto, Sh.

    2000-01-01

    Time evolution of tunneling in thermal medium is examined using the real-time semiclassical formalism previously developed. Effect of anharmonic terms in the potential well is shown to give a new mechanism of resonance enhanced tunneling. If the friction from environment is small enough, this mechanism may give a very large enhancement for the tunneling rate. The case of the asymmetric wine bottle potential is worked out in detail.

  20. Tunnelling in Dante's Inferno

    Science.gov (United States)

    Furuuchi, Kazuyuki; Sperling, Marcus

    2017-05-01

    We study quantum tunnelling in Dante's Inferno model of large field inflation. Such a tunnelling process, which will terminate inflation, becomes problematic if the tunnelling rate is rapid compared to the Hubble time scale at the time of inflation. Consequently, we constrain the parameter space of Dante's Inferno model by demanding a suppressed tunnelling rate during inflation. The constraints are derived and explicit numerical bounds are provided for representative examples. Our considerations are at the level of an effective field theory; hence, the presented constraints have to hold regardless of any UV completion.

  1. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  2. Ulnar tunnel syndrome.

    Science.gov (United States)

    Bachoura, Abdo; Jacoby, Sidney M

    2012-10-01

    Ulnar tunnel syndrome could be broadly defined as a compressive neuropathy of the ulnar nerve at the level of the wrist. The ulnar tunnel, or Guyon's canal, has a complex and variable anatomy. Various factors may precipitate the onset of ulnar tunnel syndrome. Patient presentation depends on the anatomic zone of ulnar nerve compression: zone I compression, motor and sensory signs and symptoms; zone II compression, isolated motor deficits; and zone III compression; purely sensory deficits. Conservative treatment such as activity modification may be helpful, but often, surgical exploration of the ulnar tunnel with subsequent ulnar nerve decompression is indicated.

  3. Virtual photons in macroscopic tunneling

    CERN Document Server

    Aichmann, Horst; Bruney, Paul

    2015-01-01

    Tunnelling processes are thought to proceed via virtual waves due to observed superluminal (faster than light) signal speeds. Some assume such speeds must violate causality. These assumptions contradict, for instance, superluminally tunnelled music and optical tunnelling couplers applied in fiber communication. Recently tunnelling barriers were conjectured to be cavities, wherein the tunnelled output signal is not causally related with the input. The tests described here resolve that tunnelling waves are virtual, propagations are superluminal, and causality is preserved.

  4. Use of remodeled femoral head allograft for tarsal reconstruction in the treatment of müller-weiss disease.

    Science.gov (United States)

    Tan, Anouk; Smulders, Yvonne C M M; Zöphel, Oliver T

    2011-01-01

    Müller-Weiss disease (MWD), spontaneous avascular necrosis of the navicular in adults, is rare. Without treatment, it can result in permanent disability. Operative treatment is often required. MWD was suspected in a 51-year-old woman with spontaneous pain in her right foot. The radiologic tests showed a comma shaped deformed navicular and severe talonavicular necrosis and sclerosis. After excision of the necrotic navicular, a 5 × 5 × 3-cm defect appeared. A femoral head bone allograft was remodeled to fit this defect precisely. Autologous cancellous bone was also used. The allograft interposition arthrodesis was stabilized with a low contact plate. The histopathologic results showed avascular osteonecrosis, supporting the diagnosis of MWD. After 12 weeks of non-weight-bearing plaster cast immobilization, the radiographs showed consolidation and no osteolysis. At 6 months after surgery, she was fully weight-bearing. The low contact plate was removed, because it impeded exercise. After 10 months, she was walking pain free. At 14 months after surgery, her radiographs still showed good consolidation, with no sign of osteolysis. The use of a bone allograft to cover a tarsal defect could be a safe and effective operative treatment of MWD that has not yet been reported in English-language studies. This treatment also results in minimal donor site morbidity. Copyright © 2011 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

  5. Reversible regulation of cell cycle-related genes by epigallocatechin gallate for hibernation of neonatal human tarsal fibroblasts.

    Science.gov (United States)

    Bae, Jung Yoon; Kanamune, Jun; Han, Dong-Wook; Matsumura, Kazuaki; Hyon, Suong-Hyu

    2009-01-01

    We investigated the hibernation effect of epigallocatechin-3-O-gallate (EGCG) on neonatal human tarsal fibroblasts (nHTFs) by analyzing the expression of cell cycle-related genes. EGCG application to culture media moderately inhibited the growth of nHTFs, and the removal of EGCG from culture media led to complete recovery of cell growth. EGCG resulted in a slight decrease in the cell population of the S and G(2)/M phases of cell cycle with concomitant increase in that of the G(0)/G(1) phase, but this cell cycle profile was restored to the initial level after EGCG removal. The expression of cyclin D1 (CCND1), CCNE2, CCN-dependent kinase 6 (CDK6), and CDK2 was restored, whereas that of CCNA, CCNB1, and CDK1 was irreversibly attenuated. The expression of a substantial number of genes analyzed by cDNA microarray was affected by EGCG application, and these affected expression levels were restored to the normal levels after EGCG removal. We also found the incorporation of FITC-EGCG into the cytosol of nHTFs and its further nuclear translocation, which might lead to the regulation of the exogenous signals directed to genes for cellular responses including proliferation and cell cycle progression. These results suggest that EGCG temporarily affects not only genes related to the cell cycle but also various other cellular functions.

  6. Tunnel fire dynamics

    CERN Document Server

    Ingason, Haukur; Lönnermark, Anders

    2015-01-01

    This book covers a wide range of issues in fire safety engineering in tunnels, describes the phenomena related to tunnel fire dynamics, presents state-of-the-art research, and gives detailed solutions to these major issues. Examples for calculations are provided. The aim is to significantly improve the understanding of fire safety engineering in tunnels. Chapters on fuel and ventilation control, combustion products, gas temperatures, heat fluxes, smoke stratification, visibility, tenability, design fire curves, heat release, fire suppression and detection, CFD modeling, and scaling techniques all equip readers to create their own fire safety plans for tunnels. This book should be purchased by any engineer or public official with responsibility for tunnels. It would also be of interest to many fire protection engineers as an application of evolving technical principles of fire safety.

  7. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  8. A randomized, controlled trial of the effects of resveratrol administration in performance horses with lameness localized to the distal tarsal joints.

    Science.gov (United States)

    Watts, Ashlee E; Dabareiner, Robin; Marsh, Chad; Carter, G Kent; Cummings, Kevin J

    2016-09-15

    OBJECTIVE To determine the effect of resveratrol administration in performance horses with lameness localized to the distal tarsal joints. DESIGN Randomized, blinded, placebo-controlled clinical trial. ANIMALS 45 client-owned horses with lameness localized to the distal tarsal joints. PROCEDURES All horses received injections of triamcinolone acetonide in the centrodistal and tarsometatarsal joints of both hind limbs. A placebo or a supplement containing resveratrol was fed twice daily by owners for 4 months. Primary outcomes were horse performance as determined by rider opinion (better, worse, or the same) and change in lameness severity from the enrollment examination. RESULTS Complete data were obtained for 21 horses that received resveratrol and 20 that received the placebo. Percentage of riders who reported that the horse's performance was better, compared with worse or the same, was significantly higher for the resveratrol group than for the placebo group after 2 (20/21 [95%] vs 14/20 [70%]) and 4 (18/21 [86%] vs 10/20 [50%]) months. The change in A1:A2 ratio between the enrollment and 4-month recheck examinations was significantly better for horses in the resveratrol versus placebo group. However, subjective lameness scores and degree of asymmetry of pelvis movement did not differ between groups. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that in performance horses with lameness localized to the distal tarsal joints, injection of triamcinolone in the centrodistal and tarsometatarsal joints of both hind limbs followed by oral supplementation with resveratrol for 4 months resulted in reduced lameness, compared with triamcinolone injection and supplementation with a placebo.

  9. Short- and long-term racing performance of Standardbred pacers and trotters after early surgical intervention for tarsal osteochondrosis.

    Science.gov (United States)

    McCoy, A M; Ralston, S L; McCue, M E

    2015-07-01

    Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature. To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons. Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions. Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts. © 2014 EVJ Ltd.

  10. Virtual photons in macroscopic tunneling

    OpenAIRE

    Aichmann, Horst; Nimtz, Guenter; Bruney, Paul

    2015-01-01

    Tunnelling processes are thought to proceed via virtual waves due to observed superluminal (faster than light) signal speeds. Some assume such speeds must violate causality. These assumptions contradict, for instance, superluminally tunnelled music and optical tunnelling couplers applied in fiber communication. Recently tunnelling barriers were conjectured to be cavities, wherein the tunnelled output signal is not causally related with the input. The tests described here resolve that tunnelli...

  11. Wind Tunnel Testing Facilities

    Data.gov (United States)

    Federal Laboratory Consortium — NASA Ames Research Center is pleased to offer the services of our premier wind tunnel facilities that have a broad range of proven testing capabilities to customers...

  12. INCAS TRISONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Florin MUNTEANU

    2009-09-01

    Full Text Available The 1.2 m x 1.2 m Trisonic Blowdown Wind Tunnel is the largest of the experimental facilities at the National Institute for Aerospace Research - I.N.C.A.S. "Elie Carafoli", Bucharest, Romania. The tunnel has been designed by the Canadian company DSMA (now AIOLOS and since its commissioning in 1978 has performed high speed aerodynamic tests for more than 120 projects of aircraft, missiles and other objects among which the twin jet fighter IAR-93, the jet trainer IAR-99, the MIG-21 Lancer, the Polish jet fighter YRYDA and others. In the last years the wind tunnel has been used mostly for experimental research in European projects such as UFAST. The high flow quality parameters and the wide range of testing capabilities ensure the competitivity of the tunnel at an international level.

  13. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  14. Water Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s High-Pressure Water Tunnel Facility in Pittsburgh, PA, re-creates the conditions found 3,000 meters beneath the ocean’s surface, allowing scientists to study...

  15. Wind Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — This ARDEC facility consists of subsonic, transonic, and supersonic wind tunnels to acquire aerodynamic data. Full-scale and sub-scale models of munitions are fitted...

  16. Gravity Tunnel Drag

    CERN Document Server

    Concannon, Thomas

    2016-01-01

    The time it takes to fall down a tunnel through the center of the Earth to the other side takes approximately 42 minutes, but only when given several simplifying assumptions: a uniform density Earth; a gravitational field that varies linearly with radial position; a non-rotating Earth; a tunnel evacuated of air; and zero friction along the sides of the tunnel. Though several papers have singularly relaxed the first three assumptions, in this paper we relax the final two assumptions and analyze the motion of a body experiencing these types of drag forces in the tunnel. Under such drag forces, we calculate the motion of a transport vehicle through a tunnel of the Earth under uniform density, under constant gravitational acceleration, and finally under the more realistic Preliminary Reference Earth Model (PREM) density data. We find the density profile corresponding to a constant gravitational acceleration better models the motion through the tunnel compared to the PREM density profile, and the uniform density m...

  17. Suppression of tunneling rate fluctuations in tunnel field-effect transistors by enhancing tunneling probability

    Science.gov (United States)

    Mori, Takahiro; Migita, Shinji; Fukuda, Koichi; Asai, Hidehiro; Morita, Yukinori; Mizubayashi, Wataru; Liu, Yongxun; O’uchi, Shin-ichi; Fuketa, Hiroshi; Otsuka, Shintaro; Yasuda, Tetsuji; Masahara, Meishoku; Ota, Hiroyuki; Matsukawa, Takashi

    2017-04-01

    This paper discusses the impact of the tunneling probability on the variability of tunnel field-effect transistors (TFETs). Isoelectronic trap (IET) technology, which enhances the tunneling current in TFETs, is used to suppress the variability of the ON current and threshold voltage. The simulation results show that suppressing the tunneling rate fluctuations results in suppression of the variability. In addition, a formula describing the relationship between the tunneling rate fluctuations and the electric field strength is derived based on Kane’s band-to-band tunneling model. This formula indicates that the magnitude of the tunneling rate fluctuations is proportional to the magnitude of the fluctuations in the electric field strength and a higher tunneling probability results in a lower variability. The derived relationship is universally valid for any technologies that exploit enhancement of the tunneling probability, including IET technology, channel material engineering, heterojunctions, strain engineering, etc.

  18. Early times in tunneling

    CERN Document Server

    García-Calderón, G; Garcia-Calderon, Gaston; Villavicencio, Jorge

    2000-01-01

    Exact analytical solutions of the time-dependent Schr\\"odinger equation with the initial condition of an incident cutoff wave are used to investigate the traversal time for tunneling. The probability density starts from a vanishing value along the tunneling and transmitted regions of the potential. At the barrier width it exhibits, at early times, a distribution of traversal times that typically has a peak $\\tau_p$ and a width $\\Delta \\tau$. Numerical results for other tunneling times, as the phase-delay time, fall within $\\Delta \\tau$. The B\\"uttiker traversal time is the closest to $\\tau_p$. Our results resemble calculations based on Feynman paths if its noisy behaviour is ignored.

  19. Tunneling Through Black Rings

    Institute of Scientific and Technical Information of China (English)

    ZHAO Liu

    2007-01-01

    Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzed by use of the Parikh-Wilczek tunneling method. To get the correct tunneling amplitude and emission rate, we adopt and develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronic discharge all at once, and the effect of back reaction is also taken into account. This constitutes a unified approach to the tunneling problem. Provided the first law of thermodynamics for black rings holds, the emission rate is proportional to the exponential of the change of Bekenstein-Hawking entropy. Explicit calculation for black ring temperatures agrees exactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

  20. Femtosecond scanning tunneling microscope

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, A.J.; Donati, G.P.; Rodriguez, G.; Gosnell, T.R.; Trugman, S.A.; Some, D.I.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). By combining scanning tunneling microscopy with ultrafast optical techniques we have developed a novel tool to probe phenomena on atomic time and length scales. We have built and characterized an ultrafast scanning tunneling microscope in terms of temporal resolution, sensitivity and dynamic range. Using a novel photoconductive low-temperature-grown GaAs tip, we have achieved a temporal resolution of 1.5 picoseconds and a spatial resolution of 10 nanometers. This scanning tunneling microscope has both cryogenic and ultra-high vacuum capabilities, enabling the study of a wide range of important scientific problems.

  1. Tunneling in Axion Monodromy

    CERN Document Server

    Brown, Jon; Shiu, Gary; Soler, Pablo

    2016-01-01

    The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

  2. Tunneling in axion monodromy

    Science.gov (United States)

    Brown, Jon; Cottrell, William; Shiu, Gary; Soler, Pablo

    2016-10-01

    The Coleman formula for vacuum decay and bubble nucleation has been used to estimate the tunneling rate in models of axion monodromy in recent literature. However, several of Coleman's original assumptions do not hold for such models. Here we derive a new estimate with this in mind using a similar Euclidean procedure. We find that there are significant regions of parameter space for which the tunneling rate in axion monodromy is not well approximated by the Coleman formula. However, there is also a regime relevant to large field inflation in which both estimates parametrically agree. We also briefly comment on the applications of our results to the relaxion scenario.

  3. Long distance tunneling

    CERN Document Server

    Ivlev, B I

    2005-01-01

    Quantum tunneling between two potential wells in a magnetic field can be strongly increased when the potential barrier varies in the direction perpendicular to the line connecting the two wells and remains constant along this line. A periodic structure of the wave function is formed in the direction joining the wells. The resulting motion can be coherent like motion in a conventional narrow band periodic structure. A particle penetrates the barrier over a long distance which strongly contrasts to WKB-like tunneling. The whole problem is stationary. The coherent process can be influenced by dissipation.

  4. Breaking through the tranfer tunnel

    CERN Multimedia

    Laurent Guiraud

    2001-01-01

    This image shows the tunnel boring machine breaking through the transfer tunnel into the LHC tunnel. Proton beams will be transferred from the SPS pre-accelerator to the LHC at 450 GeV through two specially constructed transfer tunnels. From left to right: LHC Project Director, Lyn Evans; CERN Director-General (at the time), Luciano Maiani, and Director for Accelerators, Kurt Hubner.

  5. Tunnelling with wormhole creation

    Energy Technology Data Exchange (ETDEWEB)

    Ansoldi, S. [National Institute of Nuclear Physics (INFN) (Italy); Tanaka, T., E-mail: tanaka@yukawa.kyoto-u.ac.jp [Kyoto University, Department of Physics (Japan)

    2015-03-15

    The description of quantum tunnelling in the presence of gravity shows subtleties in some cases. We discuss wormhole production in the context of the spherically symmetric thin-shell approximation. By presenting a fully consistent treatment based on canonical quantization, we solve a controversy present in the literature.

  6. INCAS SUBSONIC WIND TUNNEL

    Directory of Open Access Journals (Sweden)

    Corneliu STOICA

    2009-09-01

    Full Text Available The INCAS Subsonic Wind Tunnel is a closed circuit, continuous, atmospheric pressure facility with a maximum speed of 110 m/s. The test section is octagonal ,of 2.5 m wide, 2.0 m high and 4 m long. The tunnel is powered by a 1200 kW, air cooled variable speed DC motor which drives a 12 blade, 3.5 m diameter fan and is equipped with a six component pyramidal type external mechanical balance with a 700 Kgf maximum lift capacity.The angle of attack range is between -45º and +45º while the yaw angle range is between -140º and +216º .The data acquisition system has been modified recently to allow the recording of all test data on a PC - type computer using LABVIEW and a PXI – type chassis containing specialized data acquisition modules.The tunnel is equipped with a variable frequency electrical supply system for powered models and a 10 bar compressed air supply for pneumatic flow control applications.In the recent years the subsonic wind tunnel has been intensively used for tests within several European projects (AVERT, CESAR and others.

  7. Classical trajectories and quantum tunneling

    CERN Document Server

    Ivlev, B I

    2003-01-01

    The problem of inter-band tunneling in a semiconductor (Zener breakdown) in a nonstationary and homogeneous electric field is solved exactly. Using the exact analytical solution, the approximation based on classical trajectories is studied. A new mechanism of enhanced tunneling through static non-one-dimensional barriers is proposed in addition to well known normal tunneling solely described by a trajectory in imaginary time. Under certain conditions on the barrier shape and the particle energy, the probability of enhanced tunneling is not exponentially small even for non-transparent barriers, in contrast to the case of normal tunneling.

  8. Description of the male, larva and nymphal stages of Cryptocellus iaci (Arachnida, Ricinulei), with an overview of tarsal sensilla and other integumental structures.

    Science.gov (United States)

    Salvatierra, Lidianne; Tourinho, Ana Lúcia; Giribet, Gonzalo

    2013-01-01

    The male, larva and nymphal stages of Cryptocellus iaci Tourinho, Lo Man-Hung & Bonaldo, 2010, a species previously known only from a single female, are described based on specimens from around the type locality, in an area of both Terra Firme forest and igapó (flooded forests), at the Jufari River, Roraima State, Brazil. The specimens were illustrated using live photography, stereomicroscopy, and scanning electron microscopy, allowing us to examine and describe the large diversity of tarsal sensilla and other integumental structures in Cryptocellus and to compare them to those of the previously studied Pseudocellus. Based on the male somatic characters Cryptocellus iaci is placed in thefoedus species-group. Cryptocellus iaci has two sensilla of type 1 on the distal tarsomeres of legs III (DT III), while only one has been reported for Pseudocellus spp., suggesting a potential value in this type of character for systematic studies of the group.

  9. Educational Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Juozas Bielskus

    2012-12-01

    Full Text Available The paper analyzes an educational wind tunnel produced by the Department of Building Energetics (DBE of Vilnius Gediminas Technical University. The equipment could be used for performing laboratory works and simple research. The article presents the projection of inflow and outlet velocity in the working chamber of DBE wind tunnel and carries out actual noise level measurement. The received data are compared with information on the level of noise generated by the fan considering instructions provided by the manufacturer. In order to assess the reliability of the computer program, simulation applying PHOENICS software has been conducted. The aim of modeling is to simulate a pilot model and to compare the obtained results with those of an analogous test presented in scientific articles.Article in Lithuanian

  10. "Phantom" carpal tunnel syndrome.

    Science.gov (United States)

    Braverman, D L; Root, B C

    1997-10-01

    Phantom sensation is ubiquitous among persons who have had amputation; however, if it develops into phantom pain, a thorough clinical investigation must ensue. We illustrate this with the case of a 49-year-old woman, 14 years after traumatic amputation of her left 2nd through 5th fingers, and 10 years after traumatic left transfemoral amputation. She had had phantom sensation in her absent fingers for years and developed progressive pain in her phantom fingers 3 months before presentation. Nerve conduction study revealed a high-normal distal motor latency of the left median nerve and a positive Bactrian test (sensitivity 87%). She was diagnosed with "phantom" carpal tunnel syndrome and treated with a resting wrist splint, decreased weight bearing on the left upper limb, and two corticosteroid carpal tunnel injections with marked improvement. Clinicians should recognize that phantom pain may be referred from a more proximal region and may be amenable to conservative management.

  11. Carpal tunnel syndrome treatment

    Directory of Open Access Journals (Sweden)

    Emilio Filippucci

    2011-09-01

    Full Text Available Carpal tunnel syndrome, the most common peripheral neuropathy, results from compression of the median nerve at the wrist, and is a cause of pain, numbness and tingling in the upper extremities and an increasingly recognized cause of work disability. If carpal tunnel syndrome seems likely, conservative management with splinting should be initiated. Moreover, it has suggested that patients reduce activities at home and work that exacerbate symptoms. Pyridoxine and diuretics, since are largely utilised, are no more effective than placebo in relieving the symptoms. Non steroidal anti-inflammatory drugs and orally administered corticosteroids can be effective for short-term management (two to four weeks, but local corticosteroid injection may improve symptoms for a longer period. Injection is especially effective if there is no loss of sensibility or thenar-muscle atrophy and weakness, and if symptoms are intermittent rather than constant. If symptoms are refractory to conservative measures, the option of surgical therapy may be considered.

  12. [Carpal tunnel syndrome treatment].

    Science.gov (United States)

    De Angelis, Rossella; Salaffi, Fausto; Filippucci, Emilio; Grassi, Walter

    2006-01-01

    Carpal tunnel syndrome, the most common peripheral neuropathy, results from compression of the median nerve at the wrist, and is a cause of pain, numbness and tingling in the upper extremities and an increasingly recognized cause of work disability. If carpal tunnel syndrome seems likely, conservative management with splinting should be initiated. Moreover, it has suggested that patients reduce activities at home and work that exacerbate symptoms. Pyridoxine and diuretics, since are largely utilised, are no more effective than placebo in relieving the symptoms. Non steroidal anti-inflammatory drugs and orally administered corticosteroids can be effective for short-term management (two to four weeks), but local corticosteroid injection may improve symptoms for a longer period. Injection is especially effective if there is no loss of sensibility or thenar-muscle atrophy and weakness, and if symptoms are intermittent rather than constant. If symptoms are refractory to conservative measures, the option of surgical therapy may be considered.

  13. Programmable ferroelectric tunnel memristor

    Directory of Open Access Journals (Sweden)

    Andy eQuindeau

    2014-02-01

    Full Text Available We report an analogously programmable memristor based on genuine electronic resistive switching combining ferroelectric switching and electron tunneling. The tunnel current through an 8 unit cell thick epitaxial Pb(Zr[0.2]Ti[0.8]O[3] film sandwiched between La[0.7]Sr[0.3]MnO[3] and cobalt electrodes obeys the Kolmogorov-Avrami-Ishibashi model for bidimensional growth with a characteristic switching time in the order of 10^-7 seconds. The analytical description of switching kinetics allows us to develop a characteristic transfer function that has only one parameter viz. the characteristic switching time and fully predicts the resistive states of this type of memristor.

  14. The beam dump tunnels

    CERN Multimedia

    Patrice Loïez

    2002-01-01

    In these images workers are digging the tunnels that will be used to dump the counter-circulating beams. Travelling just a fraction under the speed of light, the beams at the LHC will each carry the energy of an aircraft carrier travelling at 12 knots. In order to dispose of these beams safely, a beam dump is used to extract the beam and diffuse it before it collides with a radiation shielded graphite target.

  15. Carpal tunnel release

    DEFF Research Database (Denmark)

    Larsen, Morten Bo; Sørensen, A I; Crone, K L;

    2013-01-01

    A single-blind, randomized, controlled trial was done to compare the results of carpal tunnel release using classic incision, short incision, or endoscopic technique. In total, 90 consecutive cases were included. Follow-up was 24 weeks. We found a significantly shorter sick leave in the endoscopi...... incision could be found. There were no serious complications in either group. The results indicate that the endoscopic procedure is safe and has the benefit of faster rehabilitation and return to work....

  16. Inelastic tunneling in superconducting junctions

    Energy Technology Data Exchange (ETDEWEB)

    Hlobil, Patrik Christian

    2016-06-10

    In this dissertation a theoretical formalism of elastic and inelastic tunneling spectroscopy is developed for superconductors. The underlying physical processes behind the different two tunneling channels and their implications for the interpretation of experimental tunneling data are investigated in detail, which can explain the background conductance seen in the cuprate and iron-based superconductors. Further, the properties of the emitted light from a superconducting LED are investigated.

  17. Gap anisotropy and tunneling currents. [MPS3

    DEFF Research Database (Denmark)

    Lazarides, N.; Sørensen, Mads Peter

    1996-01-01

    The tunneling Hamiltonian formalism is applied to calculate the tunnelingcurrents through a small superconducting tunnel junction. The formalism isextended to nonconstant tunneling matrix elements. The electrodes of thejunction are assumed to...

  18. Engineers win award for Swiss tunnel

    CERN Multimedia

    2003-01-01

    A Derby engineering consultancy has won the Tunnelling Industry Award 2003 for Excellence in Tunnel Design, offered by the British Tunnelling Society, for its work on the LHC in Geneva, Switzerland (1/2 page).

  19. Free lateral tarsal flap transfer for repair of skin defects of the hand%游离足跗外侧皮瓣移植修复手部软组织缺损

    Institute of Scientific and Technical Information of China (English)

    王晓峰; 李基民; 蔡晓明; 李学渊

    2012-01-01

    目的 探讨应用游离足跗外侧皮瓣移植修复手部软组织缺损的临床效果.方法 对35例手部软组织缺损,采用以足跗外侧动脉血管为蒂的足跗外侧皮瓣游离移植,皮瓣切取面积为4 cm×3 cm~8 cm×4 cm.结果 术后皮瓣全部存活,经6~ 18个月的随访,皮瓣质地好,不臃肿,色泽与手部皮肤相似,感觉恢复良好,手功能满意.结论 足跗外侧皮瓣的血管解剖恒定、皮瓣质量好,是修复中小面积的手部软组织缺损的有效方法.%Objective To explore the clinical efficacy of repairing hand skin defect by free lateral tarsal flap transfer.Methods Lateral tarsal flap free transplantation based on the lateral tarsal artery was carried out to repair skin defects of the hand in 35 cases.The size of flap ranged from 4 cm × 3 cm to 8 cm × 4 cm.Results All skin flaps survived.The follow-up time was 6 to 18 months.The flaps showed good texture and color match with no bulkiness.The sensory recovery was good and hand function was satisfactory.Conclusion The free lateral tarsal flap has a relatively consistent vascular pedicle.The flap is easy to dissect,thus is a useful option to repair small and medium size skin defects in the hand.

  20. Scanning Tunneling Microscopy

    Science.gov (United States)

    1992-03-17

    and c. M. Bertoni, J, Phys. C10, 1911 (1977); J, D. Joannoroulos and M.-r. Cohen, Phys. Rev. B10 , 5075 (1974); E. J, Mele and J. D. JOannopoulos...igh ’""f! nif ~<:ation.l’rc~mn.•hiy a pn.ltruJing ’-·luster or tJtnlp o{ a1onh at tb .. c:nd of ihis fint!t:r ad~ ~1s the tunnelling ti;". N ano

  1. A virtual detector approach to tunnel ionization and tunneling times

    CERN Document Server

    Teeny, Nicolas; Bauke, Heiko

    2016-01-01

    Tunneling times in atomic ionization is studied theoretically by a virtual detector approach. A virtual detector is a hypothetical device that allows to monitor the wave-function's density with spatial and temporal resolution during the ionization process. With this theoretical approach, it becomes possible to define unique moments when the electron enters and leaves with highest probability the classically forbidden region from first principles and a tunneling time can be specified unambiguously. It is shown that neither the moment when the electron enters the tunneling barrier nor when it leaves the tunneling barrier coincide with the moment when the external electric field reaches its maximum. Under the tunneling barrier as well as at the exit the electron has a nonzero velocity in electric field direction. This nonzero exit velocity has to be incorporated when the free motion of the electron is modeled by classical equations of motion.

  2. Tunnel face stability and ground settlement in pressurized shield tunnelling

    Institute of Scientific and Technical Information of China (English)

    苏艺; 汪国锋; 周庆宏

    2014-01-01

    An analysis of the stability of large-diameter circular tunnels and ground settlement during tunnelling by a pressurized shield was presented. An innovative three-dimensional translational multi-block failure mechanism was proposed to determine the face support pressure of large-shield tunnelling. Compared with the currently available mechanisms, the proposed mechanism has two unique features: (1) the supporting pressure applied to the tunnel face is assumed to have a non-uniform rather than uniform distribution, and (2) the method takes into account the entire circular excavation face instead of merely an inscribed ellipse. Based on the discrete element method, a numerical simulation of the Shanghai Yangtze River Tunnel was carried out using the Particle Flow Code in two dimensions. The immediate ground movement during excavation, as well as the behaviour of the excavation face, the shield movement, and the excavated area, was considered before modelling the excavation process.

  3. Magnetic tunnel junctions with monolayer hexagonal boron nitride tunnel barriers

    Energy Technology Data Exchange (ETDEWEB)

    Piquemal-Banci, M.; Galceran, R.; Bouzehouane, K.; Anane, A.; Petroff, F.; Fert, A.; Dlubak, B.; Seneor, P. [Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, Palaiseau 91767 (France); Caneva, S.; Martin, M.-B.; Weatherup, R. S.; Kidambi, P. R.; Robertson, J.; Hofmann, S. [Department of Engineering, University of Cambridge, Cambridge CB21PZ (United Kingdom); Xavier, S. [Thales Research and Technology, 1 avenue Augustin Fresnel, Palaiseau 91767 (France)

    2016-03-07

    We report on the integration of atomically thin 2D insulating hexagonal boron nitride (h-BN) tunnel barriers into Co/h-BN/Fe magnetic tunnel junctions (MTJs). The h-BN monolayer is directly grown by chemical vapor deposition on Fe. The Conductive Tip Atomic Force Microscopy (CT-AFM) measurements reveal the homogeneity of the tunnel behavior of our h-BN layers. As expected for tunneling, the resistance depends exponentially on the number of h-BN layers. The h-BN monolayer properties are also characterized through integration into complete MTJ devices. A Tunnel Magnetoresistance of up to 6% is observed for a MTJ based on a single atomically thin h-BN layer.

  4. The imaging features of the chondroblastoma in the tarsal bone%足跗骨软骨母细胞瘤的影像学表现

    Institute of Scientific and Technical Information of China (English)

    彭俊红; 周利华; 黄利华; 王慧明; 阮学广

    2012-01-01

    目的:总结分析足跗骨软骨母细胞瘤的影像学表现.方法:回顾性分析经临床病理证实的发生于足跗骨的5例软骨母细胞瘤的X线、CT及MRI表现.结果:5例均单发,2例位于跟骨,2例位于距骨,1例位于舟骨.X线主要表现为圆形或卵圆形透亮影,边界清楚,5例均可见病灶边缘硬化带形成,病灶内未见明显钙化.CT扫描显示肿瘤呈膨胀性生长,骨质破坏区边界锐利、硬化,灶周软组织肿胀,未见骨膜反应及软组织肿块,增强扫描呈轻度不均匀强化.MRI可见病灶形态呈分叶状,呈长、稍长T1信号,混杂T2信号,伴有灶周骨髓水肿及关节腔积液,灶周软组织水肿,增强扫描亦呈轻度不均匀强化.结论:足跗骨软骨母细胞瘤较少见,其影像学表现具有一定特征性.%Objective:To analyze the imaging features of the chondroblastoma in the tarsal bone,and enhance the com petence of diagnosis. Methods:The X ray,CT and MRI imaging of 5 cases with pathology proved chondroblastoma which were located in the tarsal bone were retrospectively analyzed. Results:Of all the 5 cases,the locations of tumors were as fol forws:calcaneus(n=2),talus(n=2),navicular bone (n=1).The main radiographic manifestations were round or oval translucent area witn well delined margin, sclerotic rim,and no calcilications in all lesions. On CT scan,thee tumor demon strated expansive growth patterns,by showing well defined bone destruction with sclerosis rim. The adjacent soft tissue ede ma,without periosteal reaction and soft tissue masses were observed. The contrast enhancement was mild. Lesions demon strated heterogeneous MR signal intensity on T1WI and T2 WI. Lobular margins,adjacent bone marrow edema and joint ef fusion were found. The contrast enhancement was mild too. Conclusion: Characteristic imaging features could be revealed in the uncommon cnondroblastoma of the tarsal bone,which were helpful in the diagnosis.

  5. Transposição da rima palpebral em ptose miogênica mitocondrial Tarsal switch levator for mitochondrial myogenic ptosis

    Directory of Open Access Journals (Sweden)

    Lucia Miriam Dumont Lucci

    2009-04-01

    Full Text Available OBJETIVO: Relatar o uso da ressecção do tarso da pálpebra superior e enxerto na pálpebra inferior para a elevação da rima palpebral e liberação do eixo visual, sem causar complicações corneanas em pacientes portadores de ptose miogênica mitocondrial. MÉTODOS: Estudo prospectivo. A técnica cirúrgica consiste na tarsectomia da pálpebra superior e autoenxerto do tarso na lamela posterior da pálpebra inferior. As cirurgias foram realizadas sob anestesia local. No caso de diplopia, a cirurgia foi realizada em apenas um olho. RESULTADOS: O procedimento foi realizado em 9 olhos de 6 pacientes com miopatia mitocondrial. Cinco pacientes eram do sexo feminino, a média de idade foi de 59,8 anos e o seguimento variou de 30 a 60 meses. A rima palpebral elevou em todos os pacientes, descobrindo o eixo visual na posição primária do olhar e melhorando a posição viciosa de cabeça. Não houve complicações decorrentes da exposição do globo ocular. CONCLUSÃO: A técnica de transposição da rima palpebral é útil na correção do mau posicionamento das pálpebras em pacientes sem mecanismos de proteção porque eleva a pálpebra superior e a inferior, diminuindo ou eliminando o risco de causar lagoftalmo com complicações corneanas.PURPOSE: To report the use of tarsal switch levator resection procedures that lift the palpebral fissure to visual axis without causing corneal complications in patients with mitochondrial myogenic ptosis. METHODS: Prospective study. The technique consists of an upper eyelid tarsectomy, with transfer of the autologous tarsoconjunctival graft to the posterior lamella of the lower eyelid. The surgeries were performed under local anesthesia. In case of diplopia, the surgery was performed in one eye. RESULTS: Tarsal switch procedure was performed in 9 eyes of 6 patients with mitochondrial myopathy. There were 5 women; the average age was 59.8 years and the follow-up ranged from 30 to 60 months. The palpebral

  6. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    barriers, an ability classical particles do not possess. Tunnelling is a fundamental quantum mechanical process, a process that is distinctly non-classical, so solving this tunnelling problem is not only relevant for molecular physics, but also for quantum theory in general. In this dissertation the theory...

  7. Tunneling magnetic force microscopy

    Science.gov (United States)

    Burke, Edward R.; Gomez, Romel D.; Adly, Amr A.; Mayergoyz, Isaak D.

    1993-01-01

    We have developed a powerful new tool for studying the magnetic patterns on magnetic recording media. This was accomplished by modifying a conventional scanning tunneling microscope. The fine-wire probe that is used to image surface topography was replaced with a flexible magnetic probe. Images obtained with these probes reveal both the surface topography and the magnetic structure. We have made a thorough theoretical analysis of the interaction between the probe and the magnetic fields emanating from a typical recorded surface. Quantitative data about the constituent magnetic fields can then be obtained. We have employed these techniques in studies of two of the most important issues of magnetic record: data overwrite and maximizing data-density. These studies have shown: (1) overwritten data can be retrieved under certain conditions; and (2) improvements in data-density will require new magnetic materials. In the course of these studies we have developed new techniques to analyze magnetic fields of recorded media. These studies are both theoretical and experimental and combined with the use of our magnetic force scanning tunneling microscope should lead to further breakthroughs in the field of magnetic recording.

  8. Carpal tunnel syndrome and acromegaly.

    Science.gov (United States)

    Baum, H; Lüdecke, D K; Herrmann, H D

    1986-01-01

    50 patients with acromegaly and carpal tunnel syndrome have been examined electrophysiologically before and after transnasal operation of the pituitary adenoma. 32 of the 50 patients (64%) had symptoms of carpal tunnel syndrome. 13 of them had neurological deficits. 28 of the examined patients had pathological neurographical findings only. About 1 week post-operatively DL was decreased in 43%; in 10 out of 13 patients with neurological deficits DL decreased. GH was normalized in 80% and reduced to 5-10 micrograms/l in a further 10%. The investigation did not show whether the carpal tunnel syndrome only depended on a GH increase or on other factors also such as e.g., on the duration of symptoms or tissue changes. None of the patients had the transversal carpal ligament operated on. The coincidence between acromegaly and carpal tunnel syndrome was 64%. In 3 cases the carpal tunnel syndrome was the leading sign to the diagnosis of acromegaly.

  9. Tunnel electroresistance through organic ferroelectrics

    Science.gov (United States)

    Tian, B. B.; Wang, J. L.; Fusil, S.; Liu, Y.; Zhao, X. L.; Sun, S.; Shen, H.; Lin, T.; Sun, J. L.; Duan, C. G.; Bibes, M.; Barthélémy, A.; Dkhil, B.; Garcia, V.; Meng, X. J.; Chu, J. H.

    2016-05-01

    Organic electronics is emerging for large-area applications such as photovoltaic cells, rollable displays or electronic paper. Its future development and integration will require a simple, low-power organic memory, that can be written, erased and readout electrically. Here we demonstrate a non-volatile memory in which the ferroelectric polarisation state of an organic tunnel barrier encodes the stored information and sets the readout tunnel current. We use high-sensitivity piezoresponse force microscopy to show that films as thin as one or two layers of ferroelectric poly(vinylidene fluoride) remain switchable with low voltages. Submicron junctions based on these films display tunnel electroresistance reaching 1,000% at room temperature that is driven by ferroelectric switching and explained by electrostatic effects in a direct tunnelling regime. Our findings provide a path to develop low-cost, large-scale arrays of organic ferroelectric tunnel junctions on silicon or flexible substrates.

  10. High-resolution tunnel fluctuoscopy

    Energy Technology Data Exchange (ETDEWEB)

    Glatz, A.; Varlamov, A. A.; Vinokur, V. M.

    2014-08-01

    Electron tunneling spectroscopy pioneered by Esaki and Giaever offered a powerful tool for studying electronic spectra and density of states (DOS) in superconductors. This led to important discoveries that revealed, in particular, the pseudogap in the tunneling spectrum of superconductors above their critical temperatures. However, the phenomenological approach of Giaever and Megerle does not resolve the fine structure of low-bias behavior carrying significant information about electron scattering, interactions, and decoherence effects. Here we construct a complete microscopic theory of electron tunneling into a superconductor in the fluctuation regime. We reveal a non-trivial low-energy anomaly in tunneling conductivity due to Andreev-like reflections of injected electrons from superconducting fluctuations. Our findings enable real-time observation of fluctuating Cooper pairs dynamics by time-resolved scanning tunneling microscopy measurements and open new horizons for quantitative analysis of the fluctuation electronic spectra of superconductors.

  11. 带血管蒂跗骨瓣移位术的解剖与临床应用%ANATOMY AND CLINICAL APPLICATION OF VASCULARIZED TARSAL BONE FLAPS

    Institute of Scientific and Technical Information of China (English)

    陈振光; 张发惠

    2001-01-01

    目的 为治疗距骨颈骨折、距骨体缺血性坏死和踝、足部其它骨质病损提供系列术式。方法 在30侧经动脉灌注红色乳胶的成人下肢标本上观测了供养骰骨、内侧楔骨和舟骨的主要血管,设计了上述三种带血管蒂的跗骨瓣移位术,以修复踝、足部骨质病损。并在临床应用了49例。结果 有43例经1~9年随访,平均为4年3个月,40例病损部Ⅰ期愈合,3例经二期手术治愈,踝、足功能得到极大改善。结论 上述三种跗骨瓣均具有血管蒂位置表浅,解剖容易和手术安全可靠等优点,可根据病损不同性质与部位选用。%Objective To provide a series of surgical approaches fortreatment of talus neck fracture, ischemic necrosis of talus body, and other bone lesions in ankle and foot. Methods The major blood supply to cuboid bone, medial cuneiform bone and navicular bone was observed in 30 adult cadavers, by infiltration of red emulsion via major arteries of the lower limbs. Based on these anatomical investigations, 3 types of vascularized tarsal bone grafting were designed for repair of bone lesions in the area of ankle and foot, and applied in 49 clinical cases, ranging from 10 to 58 years in age, and 43 cases of which were followed up for 4 years and 3 months in average. Results Primary healing was achieved in 40 cases, and secondary healing achieved after further surgical intervention in other 3 cases. The function of all ankle joints recovered satisfactorily. Conclusion The designed three types of vascularized tarsal bone flaps are easy and reliable for dissection because of their superficial pedicles, and they are available for different clinical cases with various bone lesions in ankle and foot.

  12. Frequency driven inversion of tunnel magnetoimpedance and observation of positive tunnel magnetocapacitance in magnetic tunnel junctions

    Science.gov (United States)

    Parui, Subir; Ribeiro, Mário; Atxabal, Ainhoa; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2016-08-01

    The relevance for modern computation of non-volatile high-frequency memories makes ac-transport measurements of magnetic tunnel junctions (MTJs) crucial for exploring this regime. Here, we demonstrate a frequency-mediated effect in which the tunnel magnetoimpedance reverses its sign in a classical Co/Al2O3/NiFe MTJ, whereas we only observe a gradual decrease in the tunnel magnetophase. Such effects are explained by the capacitive coupling of a parallel resistor and capacitor in the equivalent circuit model of the MTJ. Furthermore, we report a positive tunnel magnetocapacitance effect, suggesting the presence of a spin-capacitance at the two ferromagnet/tunnel-barrier interfaces. Our results are important for understanding spin transport phenomena at the high frequency regime in which the spin-polarized charge accumulation due to spin-dependent penetration depth at the two interfaces plays a crucial role.

  13. Frequency driven inversion of tunnel magnetoimpedance and observation of positive tunnel magnetocapacitance in magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Parui, Subir, E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu; Ribeiro, Mário; Atxabal, Ainhoa; Llopis, Roger [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); Bedoya-Pinto, Amilcar [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); Max Planck Institute of Microstructure Physics, D-06120 Halle (Germany); Sun, Xiangnan [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); National Center for Nanoscience and Technology, 100190 Beijing (China); Casanova, Fèlix; Hueso, Luis E., E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu [CIC nanoGUNE, 20018 Donostia-San Sebastian (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2016-08-01

    The relevance for modern computation of non-volatile high-frequency memories makes ac-transport measurements of magnetic tunnel junctions (MTJs) crucial for exploring this regime. Here, we demonstrate a frequency-mediated effect in which the tunnel magnetoimpedance reverses its sign in a classical Co/Al{sub 2}O{sub 3}/NiFe MTJ, whereas we only observe a gradual decrease in the tunnel magnetophase. Such effects are explained by the capacitive coupling of a parallel resistor and capacitor in the equivalent circuit model of the MTJ. Furthermore, we report a positive tunnel magnetocapacitance effect, suggesting the presence of a spin-capacitance at the two ferromagnet/tunnel-barrier interfaces. Our results are important for understanding spin transport phenomena at the high frequency regime in which the spin-polarized charge accumulation due to spin-dependent penetration depth at the two interfaces plays a crucial role.

  14. Carpal tunnel syndrome - Part II (treatment,

    Directory of Open Access Journals (Sweden)

    Michel Chammas

    2014-10-01

    Full Text Available The treatments for non-deficit forms of carpal tunnel syndrome (CTS are corticoid infiltration and/or a nighttime immobilization brace. Surgical treatment, which includes sectioning the retinaculum of the flexors (retinaculotomy, is indicated in cases of resistance to conservative treatment in deficit forms or, more frequently, in acute forms. In minimally invasive techniques (endoscopy and mini-open, and even though the learning curve is longer, it seems that functional recovery occurs earlier than in the classical surgery, but with identical long-term results. The choice depends on the surgeon, patient, severity, etiology and availability of material. The results are satisfactory in close to 90% of the cases. Recovery of strength requires four to six months after regression of the pain of pillar pain type. This surgery has the reputation of being benign and has a complication rate of 0.2–0.5%.

  15. Simulations in quantum tunneling

    Science.gov (United States)

    Smith, Kevin; Blaylock, Guy

    2017-10-01

    We study the timing effects of nonrelativistic wave packet tunneling through a barrier using a numerical simulation readily accessible to an undergraduate audience. We demonstrate that the peak of the transmitted packet can sometimes emerge from the barrier ahead of the peak of an undisturbed wave packet that does not encounter a barrier. Under the right circumstances, this effect can give the appearance that transmission through the barrier occurs at superluminal speeds. We demonstrate that this seemingly paradoxical effect is not all that puzzling. Rather, components from the front of the incoming wave packet are preferentially transmitted, forming a transmitted packet ahead of the average of the incoming wave packet but not ahead of the leading edge of that packet. Our studies also show how the timing depends on barrier height and width, consistent with expectations based on the different energy components of the wave packet.

  16. Osteossíntese distal de tíbia por transfixação tíbio-tarsal em pequenos animais

    Directory of Open Access Journals (Sweden)

    Teixeira Marcelo Weinstein

    1999-01-01

    Full Text Available Neste experimento foram utilizados 15 animais, 11 caninos e 4 felinos, portadores de fratura distal de tíbia, tratados pela imobilização tíbio-tarsal com um fixador externo. O aparelho na maioria dos casos apresentou uma configuração consistindo de dois pinos na porção proximal da tíbia, um ou dois no calcâneo e um ou dois pinos nos metatarsianos, todos conectados externamente por uma barra de acrílico autopolimerizante. O aparelho foi removido em média aos 45 dias de pós-operatório, quando foi observado radiograficamente o desaparecimento da linha de fratura óssea. Quatorze animais (93,3% tiveram recuperação funcional total do membro operado, com perfeita deambulação, uma semana após a remoção do fixador. Diante dos resultados obtidos, pode-se afirmar que a técnica é eficaz na correção de fraturas distais de tíbia, inclusive as expostas.

  17. Tunneling of atoms, nuclei and molecules

    CERN Document Server

    Bertulani, C A

    2015-01-01

    This is a brief review of few relevant topics on tunneling of composite particles and how the coupling to intrinsic and external degrees of freedom affects tunneling probabilities. I discuss the phenomena of resonant tunneling, different barriers seen by subsystems, damping of resonant tunneling by level bunching and continuum effects due to particle dissociation.

  18. Tunnel fire testing and modeling the Morgex North tunnel experiment

    CERN Document Server

    Borghetti, Fabio; Gandini, Paolo; Frassoldati, Alessio; Tavelli, Silvia

    2017-01-01

    This book aims to cast light on all aspects of tunnel fires, based on experimental activities and theoretical and computational fluid dynamics (CFD) analyses. In particular, the authors describe a transient full-scale fire test (~15 MW), explaining how they designed and performed the experimental activity inside the Morgex North tunnel in Italy. The entire organization of the experiment is described, from preliminary evaluations to the solutions found for management of operational difficulties and safety issues. This fire test allowed the collection of different measurements (temperature, air velocity, smoke composition, pollutant species) useful for validating and improving CFD codes and for testing the real behavior of the tunnel and its safety systems during a diesel oil fire with a significant heat release rate. Finally, the fire dynamics are compared with empirical correlations, CFD simulations, and literature measurements obtained in other similar tunnel fire tests. This book will be of interest to all ...

  19. Tunnel Cost-Estimating Methods.

    Science.gov (United States)

    1981-10-01

    8 ae1e 066 c LINING CALCULATES THE LINING COSTS AND THE FORMWORK COST FOR A 982928 ees C TUNNEL OR SHAFT SEGMENT 682636 0066...AD-AIO . 890 ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURGETC F/B 13/13 TUNNEL COST-ESTIMATING METNDS(U) OCT 81 R D BENNETT UNCLASSIFIED WES...TR/L-81-101-3lEEEEEE EIIIl-IIIIIIIu IIIIEIIIEIIIIE llllEEEEllEEEI EEEEEEEEEIIII C EllTE-CHNICAL RGPORT GL-81-10 LI10 TUNNEL COST-ESTIMATING METHODS by

  20. Quantum Tunneling and Complex Trajectories

    Science.gov (United States)

    Meynig, Max; Haggard, Hal

    2017-01-01

    In general, the semiclassical approximation of quantum mechanical tunneling fails to treat tunneling through barriers if real initial conditions and trajectories are used. By analytically continuing classical dynamics to the complex plane the problems encountered in the approximation can be resolved. While, the complex methods discussed here have been previously explored, no one has exhibited an analytically solvable case. The essential features of the complex method will be discussed in the context of a novel, analytically solvable problem. These methods could be useful in quantum gravity, with applications to the tunneling of spacetime geometries.

  1. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  2. Dynamical tunneling theory and experiment

    CERN Document Server

    Keshavamurthy, Srihari

    2011-01-01

    A prominent aspect of quantum theory, tunneling arises in a variety of contexts across several fields of study, including nuclear, atomic, molecular, and optical physics and has led to technologically relevant applications in mesoscopic science. Exploring mechanisms and consequences, Dynamical Tunneling: Theory and Experiment presents the work of international experts who discuss the considerable progress that has been achieved in this arena in the past two decades.Highlights in this volume include:A historical introduction and overview of dynamical tunneling, with case histories ranging from

  3. Free Surface Water Tunnel (FSWT)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Free Surface Water Tunnel consists of the intake plenum, the test section and the exit plenum. The intake plenum starts with a perforated pipe that...

  4. Flatback airfoil wind tunnel experiment.

    Energy Technology Data Exchange (ETDEWEB)

    Mayda, Edward A. (University of California, Davis, CA); van Dam, C.P. (University of California, Davis, CA); Chao, David D. (University of California, Davis, CA); Berg, Dale E.

    2008-04-01

    A computational fluid dynamics study of thick wind turbine section shapes in the test section of the UC Davis wind tunnel at a chord Reynolds number of one million is presented. The goals of this study are to validate standard wind tunnel wall corrections for high solid blockage conditions and to reaffirm the favorable effect of a blunt trailing edge or flatback on the performance characteristics of a representative thick airfoil shape prior to building the wind tunnel models and conducting the experiment. The numerical simulations prove the standard wind tunnel corrections to be largely valid for the proposed test of 40% maximum thickness to chord ratio airfoils at a solid blockage ratio of 10%. Comparison of the computed lift characteristics of a sharp trailing edge baseline airfoil and derived flatback airfoils reaffirms the earlier observed trend of reduced sensitivity to surface contamination with increasing trailing edge thickness.

  5. Self-Organizing Tunnel Peers

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Tunneling is an important approach in IPv6 transition techniques. The tunnel broker model provides a way to build virtual IPv6 networks without manual configuration.However, neither it adapts performance variation on the IPv4 infrastructure,nor it is a scalable solution for a wide-area IPv6 networking environment. In this paper, a self-organizing tunnel peer (SOTP)model is presented. Tunnel peers are clustered in the SOTP system so that optimization is scalable. Four primitive operations related to cluster construction - arrest,release,division and death - endow the system with the nature of self-organization.Occurrence and behavior of the operations are decided by criteria on the IPv4 end-to-end performance; hence measurement is an indispensable component of the system. The metabolism of cluster relaxes the requirement to accuracy of measurement and optimization.

  6. The Statistics of Chaotic Tunnelling

    CERN Document Server

    Creagh, S C; Creagh, Stephen C.; Whelan, Niall D.

    2000-01-01

    We discuss the statistics of tunnelling rates in the presence of chaotic classical dynamics. This applies to resonance widths in chaotic metastable wells and to tunnelling splittings in chaotic symmetric double wells. The theory is based on using the properties of a semiclassical tunnelling operator together with random matrix theory arguments about wave function overlaps. The resulting distribution depends on the stability of a specific tunnelling orbit and is therefore not universal. However it does reduce to the universal Porter-Thomas form as the orbit becomes very unstable. For some choices of system parameters there are systematic deviations which we explain in terms of scarring of certain real periodic orbits. The theory is tested in a model symmetric double well problem and possible experimental realisations are discussed.

  7. 5-foot Vertical Wind Tunnel

    Science.gov (United States)

    1932-01-01

    The researcher is sitting above the exit cone of the 5-foot Vertical Wind Tunnel and is examining the new 6-component spinning balance. This balance was developed between 1930 and 1933. It was an important advance in the technology of rotating or rolling balances. As M.J. Bamber and C.H. Zimmerman wrote in NACA TR 456: 'Data upon the aerodynamic characteristics of a spinning airplane may be obtained in several ways; namely, flight tests with full-scale airplanes, flight tests with balanced models, strip-method analysis of wind-tunnel force and moment tests, and wind-tunnel tests of rotating models.' Further, they note: 'Rolling-balance data have been of limited value because it has not been possible to measure all six force and moment components or to reproduce a true spinning condition. The spinning balance used in this investigation is a 6-component rotating balance from which it is possible to obtain wind-tunnel data for any of a wide range of possible spinning conditions.' Bamber and Zimmerman described the balance as follows: 'The spinning balance consists of a balance head that supports the model and contains the force-measuring units, a horizontal turntable supported by streamline struts in the center of the jet and, outside the tunnel, a direct-current driving motor, a liquid tachometer, an air compressor, a mercury manometer, a pair of indicating lamps, and the necessary controls. The balance head is mounted on the turntable and it may be set to give any radius of spin between 0 and 8 inches.' In an earlier report, NACA TR 387, Carl Wenzinger and Thomas Harris supply this description of the tunnel: 'The vertical open-throat wind tunnel of the National Advisory Committee for Aeronautics ... was built mainly for studying the spinning characteristics of airplane models, but may be used as well for the usual types of wind-tunnel tests. A special spinning balance is being developed to measure the desired forces and moments with the model simulating the actual

  8. Submucosal tunneling techniques: current perspectives

    Directory of Open Access Journals (Sweden)

    Kobara H

    2014-04-01

    Full Text Available Hideki Kobara,1 Hirohito Mori,1 Kazi Rafiq,2 Shintaro Fujihara,1 Noriko Nishiyama,1 Maki Ayaki,1 Tatsuo Yachida,1 Tae Matsunaga,1 Johji Tani,1 Hisaaki Miyoshi,1 Hirohito Yoneyama,1 Asahiro Morishita,1 Makoto Oryu,1 Hisakazu Iwama,3 Tsutomu Masaki1 1Department of Gastroenterology and Neurology, 2Department of Pharmacology, 3Life Science Research Center, Faculty of Medicine, Kagawa University, Miki-cho, Kita-Gun, Kagawa, Japan Abstract: Advances in endoscopic submucosal dissection include a submucosal tunneling technique, involving the introduction of tunnels into the submucosa. These tunnels permit safer offset entry into the peritoneal cavity for natural orifice transluminal endoscopic surgery. Technical advantages include the visual identification of the layers of the gut, blood vessels, and subepithelial tumors. The creation of a mucosal flap that minimizes air and fluid leakage into the extraluminal cavity can enhance the safety and efficacy of surgery. This submucosal tunneling technique was adapted for esophageal myotomy, culminating in its application to patients with achalasia. This method, known as per oral endoscopic myotomy, has opened up the new discipline of submucosal endoscopic surgery. Other clinical applications of the submucosal tunneling technique include its use in the removal of gastrointestinal subepithelial tumors and endomicroscopy for the diagnosis of functional and motility disorders. This review suggests that the submucosal tunneling technique, involving a mucosal safety flap, can have potential values for future endoscopic developments. Keywords: submucosal endoscopy, submucosal tunneling method, natural orifice transluminal endoscopic surgery, peroral endoscopic myotomy, gastrointestinal subepithelial tumor, functional and motility disorders

  9. Current noise in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

    2017-06-15

    We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. TunnelVision: LHC Tunnel Photogrammetry System for Structural Monitoring

    CERN Document Server

    Fallas, William

    2014-01-01

    In this document an algorithm to detect deformations in the LHC Tunnel of CERN is presented. It is based on two images, one represents the ideal state of the tunnel and the other one the actual state. To find the differences between both, the algorithm is divided in three steps. First, an image enhancement is applied to make easier the detection. Second, two different approaches to reduce noise are applied to one or both images. And third, it is defined a group of characteristics about the type of deformation desired to detect. Finally, the conclusions show the effectiveness of the algorithm in the experimental results.

  11. Design of tunneling injection quantum dot lasers

    Institute of Scientific and Technical Information of China (English)

    JIA Guo-zhi; YAO Jiang-hong; SHU Yong-chun; WANG Zhan-guo

    2007-01-01

    To implement high quality tunneling injection quantum dot lasers,effects of primary factors on performance of the tunneling injection quantum dot lasers were investigated. The considered factors were tunneling probability,tunneling time and carriers thermal escape time from the quantum well. The calculation results show that with increasing of the ground-state energy level in quantum well,the tunneling probability increases and the tunneling time decreases,while the thermal escape time decreases because the ground-state energy levelis shallower. Longitudinal optical phonon-assisted tunneling can be an effective method to solve the problem that both the tunneling time and the thermal escape time decrease simultaneously with the ground-state energy level increasing in quantum well.

  12. Tunneling field effect transistor technology

    CERN Document Server

    Chan, Mansun

    2016-01-01

    This book provides a single-source reference to the state-of-the art in tunneling field effect transistors (TFETs). Readers will learn the TFETs physics from advanced atomistic simulations, the TFETs fabrication process and the important roles that TFETs will play in enabling integrated circuit designs for power efficiency. · Provides comprehensive reference to tunneling field effect transistors (TFETs); · Covers all aspects of TFETs, from device process to modeling and applications; · Enables design of power-efficient integrated circuits, with low power consumption TFETs.

  13. Quantum Cosmology for Tunneling Universes

    CERN Document Server

    Kim, Sang Pyo

    2004-01-01

    In a quantum cosmological model consisting of a Euclidean region and a Lorentzian region, Hartle-Hawking's no-bounary wave function, and Linde's wave function and Vilenkin's tunneling wave function are briefly described and compared with each other. We put a particular emphasis on semiclassical gravity from quantum cosmology and compare it with the conventional quantum field theory in curved spacetimes. Finally, we discuss the recent debate on catastrophic particle production in the tunneling universe between Rubakov and Vilenkin within the semiclassical gravity.

  14. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Anupam Garg

    2001-02-01

    We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the space of magnetic fields, known as diabolical points. This phenomena is explained in terms of two approaches, one based on spin-coherent-state path integrals, and the other on a generalization of the phase integral (or WKB) method to difference equations. Explicit formulas for the diabolical points are obtained for a model Hamiltonian.

  15. Tunneling in high-K isomeric decays

    CERN Document Server

    Shizuma, T; Shimizu, Y R

    2002-01-01

    We have systematically investigated highly-K-forbidden transitions observed in the Hf, W and Os region, using the gamma-tunneling model in which low-K and high-k states interact through a process of quantum tunneling. The measured hindrance factors are compared with the values calculated using the gamma-tunneling model. Isotope dependences of gamma-tunneling probabilities particularly for neutron-rich nuclei and the relation to stimulated decays of isomers are discussed. (author)

  16. Drill and blast tunnelling; Konvensjonell drift av tunneler

    Energy Technology Data Exchange (ETDEWEB)

    Roenn, Paal-Egil

    1997-12-31

    This thesis treats drill and blast tunnelling. The rapid technological advance necessitates revised and updated design criteria, quality requirements and quality control. In situ blast experiments were carried out in order to test new methods and improve the basis for calculation and design. The main topics of the experiments were (1) longer rounds and increased drillhole diameter, (2) emulsion slurry as explosives in tunnelling, and (3) electronic detonators in contour blasting. The experiments show that it is technically feasible to blast rounds of up to 8.6 m length. Using current technology, the economical optimum round length is substantially shorter. Dust, low visibility, noise and toxic fumes are occupational environmental strains for the tunnel workers. Several of the environmental factors are strongly influenced by the type of explosives used. For example, emulsion slurry resulted in 4 to 5 times better visibility than Anolit and the concentration of respirable dust and total dust was reduced by 30-50 %. Electronic detonators were tested and found to give a higher percentage of remaining drillholes in the contour than Nonel detonators. The thesis includes a chapter on economic design of hydropower tunnels. 42 refs., 83 figs., 45 tabs.

  17. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...

  18. Tunnel Face Stability & New CPT Applications

    NARCIS (Netherlands)

    Broere, W.

    2001-01-01

    Nearly all tunnels bored in soft soils have encountered problems with the stability of the tunnel face. In several cases these problems led to an extended stand-still of the boring process. A better understanding of the face stability, and of the soil conditions around the tunnel boring machine, can

  19. A Wind Tunnel Captive Aircraft Testing Technique

    Science.gov (United States)

    1976-04-01

    Flight/Wind Tunnel Correlation of Aircraft Longitudinal Motion ....................................... 14 10. Fright/Wind Tunnel Correlation of...I 2 3 4 5 6 T IME, s e c Figure 9. Flight/wind tunnel correla- tion of aircraft longitudinal motion. ’ D A n ~ v i i i | ~ 0 0 - 4 0

  20. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...

  1. The road safety of motorway tunnels.

    NARCIS (Netherlands)

    2009-01-01

    This fact sheet discusses the safety of motorway tunnels in the Netherlands. Broadly speaking, it is not certain whether crashes in the Netherlands are relatively more frequent in tunnels than on open road stretches. However, there are certain factors that increase the risk in tunnels, such as the p

  2. Acute pancreatitis

    Science.gov (United States)

    ... its blood vessels. This problem is called acute pancreatitis. Acute pancreatitis affects men more often than women. Certain ... pancreatitis; Pancreas - inflammation Images Digestive system Endocrine glands Pancreatitis, acute - CT scan Pancreatitis - series References Forsmark CE. Pancreatitis. ...

  3. Cystitis - acute

    Science.gov (United States)

    Uncomplicated urinary tract infection; UTI - acute cystitis; Acute bladder infection; Acute bacterial cystitis ... cause. Menopause also increases the risk for a urinary tract infection. The following also increase your chances of having ...

  4. Time tunnels meet warped passages

    CERN Multimedia

    Kushner, David

    2006-01-01

    "Just in time for its 40th anniversary, the classic sci-fi television show "The time tunnel" is out on DVD. The conceit is something every engineer can relate to: a pulled plug. Scientists in an underground lab are working on a secret government experiment in time travel. (1 page)

  5. Tunnel lighting in Europe (abridged).

    NARCIS (Netherlands)

    Schreuder, D.A.

    1972-01-01

    A set of principles embodied in 1971 recommendations of the cie (commission internationale de l'eclairage - international commission on lighting) is beginning to be generally accepted throughout europe, so that it is now possible to speak of a european system of tunnel lighting." the recommendations

  6. The recurrent carpal tunnel syndrome.

    Science.gov (United States)

    Kern, B C; Brock, M; Rudolph, K H; Logemann, H

    1993-01-01

    Sixteen out of 720 patients with carpal tunnel syndrome who had undergone surgery since 1979 were reoperated for a "recurrence" (2.2%). Twelve of these patients had been originally operated on in our department. Thus, our own recurrence rate is 1.7%. Three patients deteriorated following surgery, 6 had an unsatisfactory improvement, and in 7 the symptoms recurred after initial improvement. Eight of the reoperated patients had a predisposing disease (terminal renal insufficiency, insulin-dependent diabetes mellitus, acromegaly). In 10 of the 16 cases the initial operation had been carried out by surgeons in the first three years of training. Reoperation revealed incomplete splitting of the transverse carpal ligament in 10 cases, compression of the median nerve by the scar in 4, injury of the muscular branch in 1, and an anatomical variant as cause of incomplete decompression in 1 patient. "Recurrences" after carpal tunnel surgery are predominantly due to inadequacies of the first procedure. A remarkable number of patients (50%) has predisposing diseases. Interfascicular or epineural neurolysis and complete exposure and neurolysis of the median nerve and its branches is necessary only in cases of recurrence. Their omission at the first surgery does not result in an increased recurrence rate. Our observations indicate that the number of operations for recurrent carpal tunnel syndrome can probably be reduced when the first operation is performed with care and experience. Patients with carpal tunnel syndrome secondary to a systemic disease are particularly at risk.

  7. Introduction to scanning tunneling microscopy

    CERN Document Server

    Chen, C Julian

    2008-01-01

    The scanning tunneling and the atomic force microscope, both capable of imaging individual atoms, were crowned with the Physics Nobel Prize in 1986, and are the cornerstones of nanotechnology today. This is a thoroughly updated version of this 'bible' in the field.

  8. A Seamless Ubiquitous Telehealthcare Tunnel

    Directory of Open Access Journals (Sweden)

    Sao-Jie Chen

    2013-08-01

    Full Text Available Mobile handheld devices are rapidly using to implement healthcare services around the World. Fundamentally, these services utilize telemedicine technologies. A disconnection of a mobile telemedicine system usually results in an interruption, which is embarrassing, and reconnection is necessary during the communication session. In this study, the Stream Control Transmission Protocol (SCTP is adopted to build a stable session tunnel to guarantee seamless switching among heterogeneous wireless communication standards, such as Wi-Fi and 3G. This arrangement means that the telemedicine devices will not be limited by a fixed wireless connection and can switch to a better wireless channel if necessary. The tunnel can transmit plain text, binary data, and video streams. According to the evaluation of the proposed software-based SCTP-Tunnel middleware shown, the performance is lower than anticipated and is slightly slower than a fixed connection. However, the transmission throughput is still acceptable for healthcare professionals in a healthcare enterprise or home care site. It is necessary to build more heterogeneous wireless protocols into the proposed tunnel-switching scheme to support all possible communication protocols. In addition, SCTP is another good choice for promoting communication in telemedicine and healthcare fields.

  9. Tunneling in the SIS Structure

    Science.gov (United States)

    Shukrinov, Yu.; Kohandel, M.

    2000-09-01

    We discuss the effects caused by the layered structure of high temperature superconductors (HTS). We use the layered S-N model to obtain the tunneling current of the SIS structure. The current-voltage characteristic is calculated in the limit cases when dI/dV is proportional to the state density of HTS.

  10. Installation in the SPS tunnel

    CERN Multimedia

    1974-01-01

    The SPS tunnel is 6910 m in circumference and has a cross section of 4 m inner diameter. It is situated at an elevation of 400 m above sea level at a depth below the surface varying between 23 and 65 m. Its walls are lined with a concrete shell of about 30 cm thickness. See also 7410043X

  11. Travelling inside the SPS tunnel

    CERN Multimedia

    1974-01-01

    The golf cart proved to be a very useful form of transport around the 7 km circumference of the machine. It could carry four passengers and pull light equipment in its trailer. Here Peter Zettwoch is the driver along a mock-up tunnel for installation tests. (see photo 7401011X and Photo Archive 7401018)

  12. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  13. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  14. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc bias...

  15. Inelastic scattering in resonant tunneling

    DEFF Research Database (Denmark)

    Wingreen, Ned S.; Jacobsen, Karsten Wedel; Wilkins, John W.

    1989-01-01

    The exact resonant-tunneling transmission probability for an electron interacting with phonons is presented in the limit that the elastic coupling to the leads is independent of energy. The phonons produce transmission sidebands but do not affect the integrated transmission probability or the esc...

  16. Tunnel widening in anterior cruciate ligament reconstruction

    DEFF Research Database (Denmark)

    Clatworthy, M G; Annear, P; Bulow, J U

    1999-01-01

    .1% in the patella tendon group (P = film measurements. Tunnel widening did not correlate with the clinical findings, knee scores, KT-1000 or isokinetic muscle strength. Tunnel widening is marked in the hamstring group. Tunnel widening does not correlate with instability......We report a prospective series evaluating the incidence and degree of tunnel widening in a well-matched series of patients receiving a hamstring or patella tendon graft for anterior cruciate ligament (ACL) deficiency. We correlated tunnel widening with clinical factors, knee scores, KT-1000...

  17. An Entropic Formulation of Tunneling Time

    CERN Document Server

    Demir, Durmus A

    2015-01-01

    Quantum tunneling governs numerous phenomena in biology, chemistry, physics and technology. Tunneling time, formulated in various different forms due to the absence of a time operator in quantum theory, has been measured recently in experiments based on the attoclock in ultrafast laser ionization of Helium atoms [A.~Landsman {\\it et al.}, Optica {\\bf 1}, 343 (2014)]. The experiment performs a refined measurement with which no tunneling time formula in the literature exhibits adequate congruence. Here we show that, entropic considerations lead to a real tunneling time which shows remarkable agreement with the experimental data and stays always subluminal. Indeed, with phase space volume setting the number of microstates for a single evanescing particle in a state of definite momentum consistent with energy conservation, one is naturally led to a statistical description for quantum tunneling in which thermal energy sets the tunneling time. This entropic tunneling time is rather general and might also be extende...

  18. Tunneling Flight Time, Chemistry, and Special Relativity.

    Science.gov (United States)

    Petersen, Jakob; Pollak, Eli

    2017-08-15

    Attosecond ionization experiments have not resolved the question "What is the tunneling time?". Different definitions of tunneling time lead to different results. Second, a zero tunneling time for a material particle suggests that the nonrelativistic theory includes speeds greater than the speed of light. Chemical reactions, occurring via tunneling, should then not be considered in terms of a nonrelativistic quantum theory calling into question quantum dynamics computations on tunneling reactions. To answer these questions, we define a new experimentally measurable paradigm, the tunneling flight time, and show that it vanishes for scattering through an Eckart or a square barrier, irrespective of barrier length or height, generalizing the Hartman effect. We explain why this result does not lead to experimental measurement of speeds greater than the speed of light. We show that this tunneling is an incoherent process by comparing a classical Wigner theory with exact quantum mechanical computations.

  19. MANAGEMENT OF TUNNELS ON THE ZAGREB – MACELJ MOTORWAY IN THE COURSE OF TUNNELS EXPLOITATION

    Directory of Open Access Journals (Sweden)

    Zvonimir Deković

    2012-12-01

    Full Text Available he paper focuses on the features of management of tunnels on the Zagreb-Macelj motorway. Management of tunnels is represented trough public-private partnership model that is applied on the Zagreb-Macelj motorway. In the course of tunnel operation and maintenance in the first five years of tunnels exploitation, the emphasis is put on the maintenance of the tunnel equipment systems. Tunnels as part of the motorway alignment are the most demanding facilities for maintaining appropriate safety and operational level in order to rich continuous availability providing safe and quality of service to the motorway users. The goal of the tunnel operation and maintenance is to ensure undisturbed and safe traffic flow through the tunnels by keeping the tunnel at the normal functional conditions.

  20. In-Tunnel Blast Pressure Empirical Formulas for Detonations External, Internal and at the Tunnel Entrance

    Institute of Scientific and Technical Information of China (English)

    LI Xiudi; ZHENG Yingren

    2006-01-01

    In order to define the loading on protective doors of an underground tunnel,the exact knowledge of the blast propagation through tunnels is needed.Thirty-three scale high-explosive tests are conducted to obtain in-tunnel blast pressure for detonations external,internal and at the tunnel entrance.The cross section of the concrete model tunnel is 0.67 m2.Explosive charges of TNT,ranging in mass from 400 g to 4 600 g,are detonated at various positions along the central axis of the model tunnel.Blast gages are flush-installed in the interior surface of the tunnel to record side-on blast pressure as it propagates down the tunnel.The engineering empirical formulas for predicting blast peak pressure are evaluated,and are found to be reasonably accurate for in-tunnel pressure prediction.

  1. Resonant tunnel magnetoresistance in a double magnetic tunnel junction

    KAUST Repository

    Useinov, Arthur

    2011-08-09

    We present quasi-classical approach to calculate a spin-dependent current and tunnel magnetoresistance (TMR) in double magnetic tunnel junctions (DMTJ) FML/I/FMW/I/FMR, where the magnetization of the middle ferromagnetic metal layer FMW can be aligned parallel or antiparallel with respect to the fixed magnetizations of the left FML and right FMR ferromagnetic electrodes. The transmission coefficients for components of the spin-dependent current, and TMR are calculated as a function of the applied voltage. As a result, we found a high resonant TMR. Thus, DMTJ can serve as highly effective magnetic nanosensor for biological applications, or as magnetic memory cells by switching the magnetization of the inner ferromagnetic layer FMW.© Springer Science+Business Media, LLC 2011.

  2. Acute Bronchitis

    Science.gov (United States)

    ... Smoking also slows down the healing process. Acute bronchitis treatment Most cases of acute bronchitis can be treated at home.Drink fluids, but ... bronchial tree. Your doctor will decide if this treatment is right for you. Living with acute bronchitis Most cases of acute bronchitis go away on ...

  3. 足跗外侧动脉岛状皮瓣修复足前部皮肤缺损%Reconstruction of forefoot skin defect with island flap pedicled with lateral tarsal artery

    Institute of Scientific and Technical Information of China (English)

    张继春; 张伟; 夏晓明; 张亮; 韩金豹

    2012-01-01

    目的 探讨足跗外侧动脉岛状皮瓣修复足前部皮肤缺损的临床疗效.方法 2007年3月至2009年1月,应用足跗外侧动脉逆行岛状皮瓣修复足前部皮肤缺损患者12例.结果 12例皮瓣均完全成活.随访8 ~ 22个月,平均13个月.皮瓣及皮片质地柔软,色泽与周围正常皮肤相似,外观无臃肿,无需二期皮瓣修整.受区皮瓣感觉以深痛觉为主,皮瓣边缘1 ~2 cm范围有浅触觉和痛觉恢复,即皮瓣边缘感觉为S1 ~S2级.供区皮片有浅触觉和痛觉恢复,未发现皮瓣磨损及破溃,穿鞋无影响,患者步态正常.结论 跗外侧动脉岛状皮瓣对足部的影响较小,是修复足前部软组织缺损的良好选择.%Objective To investigate the therapeutic effect of island flap pedicled with lateral tarsal artery for forefoot skin defect.Methods From March 2007 to January 2009,12 cases with forefoot skin defects were treated by reversed island flap pedicled with lateral tarsal artery.Results All the flaps survived completely with a followed-up period of 8-22 months,13 months in average.The flaps and skin grafts had soft texture and a similar color as the surrounding skin.The flaps had a suitable thickness with deep pain sensation.Shallow touch and pain sensation recovered in the skin graft and within 1-2 cm of the flap edge,which was graded as S1-S2.There was no problem in shoes-wearing and walking.No flap ulcer happened.Conclusion Island flap pedicled with lateral tarsal artery is suitable for forefoot skin defect,leaving less morbidity to donor site.

  4. Wildlife Tunnel Enhances Population Viability

    Directory of Open Access Journals (Sweden)

    Rodney van der Ree

    2009-12-01

    Full Text Available Roads and traffic are pervasive components of landscapes throughout the world: they cause wildlife mortality, disrupt animal movements, and increase the risk of extinction. Expensive engineering solutions, such as overpasses and tunnels, are increasingly being adopted to mitigate these effects. Although some species readily use such structures, their success in preventing population extinction remains unknown. Here, we use population viability modeling to assess the effectiveness of tunnels for the endangered Mountain Pygmy-possum (Burramys parvus in Australia. The underpasses reduced, but did not completely remove, the negative effects of a road. The expected minimum population size of a "reconnected" population remained 15% lower than that of a comparable "undivided" population. We propose that the extent to which the risk of extinction decreases should be adopted as a measure of effectiveness of mitigation measures and that the use of population modeling become routine in these evaluations.

  5. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  6. Single-contact tunneling thermometry

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-02-23

    A single-contact tunneling thermometry circuit includes a tunnel junction formed between two objects. Junction temperature gradient information is determined based on a mathematical relationship between a target alternating voltage applied across the junction and the junction temperature gradient. Total voltage measured across the junction indicates the magnitude of the target alternating voltage. A thermal gradient is induced across the junction. A reference thermovoltage is measured when zero alternating voltage is applied across the junction. An increasing alternating voltage is applied while measuring a thermovoltage component and a DC rectification voltage component created by the applied alternating voltage. The target alternating voltage is reached when the thermovoltage is nullified or doubled by the DC rectification voltage depending on the sign of the reference thermovoltage. Thermoelectric current and current measurements may be utilized in place of the thermovoltage and voltage measurements. The system may be automated with a feedback loop.

  7. Tunneling magnetoresistance in Si nanowires

    Science.gov (United States)

    Montes, E.; Rungger, I.; Sanvito, S.; Schwingenschlögl, U.

    2016-11-01

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green’s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  8. Tunneling magnetoresistance in Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2016-11-09

    We investigate the tunneling magnetoresistance of small diameter semiconducting Si nanowires attached to ferromagnetic Fe electrodes, using first principles density functional theory combined with the non-equilibrium Green\\'s functions method for quantum transport. Silicon nanowires represent an interesting platform for spin devices. They are compatible with mature silicon technology and their intrinsic electronic properties can be controlled by modifying the diameter and length. Here we systematically study the spin transport properties for neutral nanowires and both n and p doping conditions. We find a substantial low bias magnetoresistance for the neutral case, which halves for an applied voltage of about 0.35 V and persists up to 1 V. Doping in general decreases the magnetoresistance, as soon as the conductance is no longer dominated by tunneling.

  9. Dissipative Effect and Tunneling Time

    Directory of Open Access Journals (Sweden)

    Samyadeb Bhattacharya

    2011-01-01

    Full Text Available The quantum Langevin equation has been studied for dissipative system using the approach of Ford et al. Here, we have considered the inverted harmonic oscillator potential and calculated the effect of dissipation on tunneling time, group delay, and the self-interference term. A critical value of the friction coefficient has been determined for which the self-interference term vanishes. This approach sheds new light on understanding the ion transport at nanoscale.

  10. AUTONOMOUS ROBOTIC INSPECTION IN TUNNELS

    OpenAIRE

    E. Protopapadakis; Stentoumis, C.; Doulamis, N.; A. Doulamis; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-01-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel’s lining, for a narrow region clos...

  11. Variable density turbulence tunnel facility

    Science.gov (United States)

    Bodenschatz, E.; Bewley, G. P.; Nobach, H.; Sinhuber, M.; Xu, H.

    2014-09-01

    The Variable Density Turbulence Tunnel at the Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, produces very high turbulence levels at moderate flow velocities, low power consumption, and adjustable kinematic viscosity between 10-4 m2/s and 10-7 m2/s. The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. The highest kinematic viscosities, and hence lowest Reynolds numbers, are reached with air or nitrogen at 0.1 bar. To reach the highest Reynolds numbers the tunnel is pressurized to 15 bars with the dense gas sulfur hexafluoride (SF6). Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [M. Vallikivi, M. Hultmark, S. C. C. Bailey, and A. J. Smits, Exp. Fluids 51, 1521 (2011)]. We report measurements of the characteristic scales of the flow and of turbulent spectra up to Taylor Reynolds number Rλ ≈ 1600, higher than any other grid-turbulence experiment. We also describe instrumentation under development, which includes an active grid and a Lagrangian particle tracking system that moves down the length of the tunnel with the mean flow. In this configuration, the properties of the turbulence are adjustable and its structure is resolvable up to Rλ ≈ 8000.

  12. Apparent tunneling in chemical reactions

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm; Hansen, Flemming Yssing; Billing, G. D.

    2000-01-01

    A necessary condition for tunneling in a chemical reaction is that the probability of crossing a barrier is non-zero, when the energy of the reactants is below the potential energy of the barrier. Due to the non-classical nature (i.e, momentum uncertainty) of vibrational states this is, however, ...... to the high momentum tail of the initial vibrational state of nitrogen, allowing for amplitude to cross over the barrier. (C) 2000 Elsevier Science B.V. All rights reserved....

  13. Electrodiagnosis of carpal tunnel syndrome.

    Science.gov (United States)

    Wang, Leilei

    2013-02-01

    This article discusses the historical aspects related to the understanding of carpal tunnel syndrome (CTS) and its diagnosis, highlighting observations about this disease that have yet to be challenged. This is followed by a discussion regarding the use of electrodiagnostic testing as a diagnostic tool for CTS, as well as the author's approach to making the diagnosis of CTS. Finally, conclusions about future directions in the diagnosis and treatment of this disorder are presented.

  14. Digging the CNGS decay tunnel

    CERN Multimedia

    Patrice Loiez

    2002-01-01

    Products of the collision between a proton beam and a graphite target will pass through a horn containing an electric field that will produce a focused beam. These particles will decay into muon neutrinos within the tunnel that is being constructed in these images. The neutrinos will then travel 730 km to Gran Sasso in Italy where huge detectors will observe the beam to study a process called neutrino oscillation.

  15. Autonomous Robotic Inspection in Tunnels

    Science.gov (United States)

    Protopapadakis, E.; Stentoumis, C.; Doulamis, N.; Doulamis, A.; Loupos, K.; Makantasis, K.; Kopsiaftis, G.; Amditis, A.

    2016-06-01

    In this paper, an automatic robotic inspector for tunnel assessment is presented. The proposed platform is able to autonomously navigate within the civil infrastructures, grab stereo images and process/analyse them, in order to identify defect types. At first, there is the crack detection via deep learning approaches. Then, a detailed 3D model of the cracked area is created, utilizing photogrammetric methods. Finally, a laser profiling of the tunnel's lining, for a narrow region close to detected crack is performed; allowing for the deduction of potential deformations. The robotic platform consists of an autonomous mobile vehicle; a crane arm, guided by the computer vision-based crack detector, carrying ultrasound sensors, the stereo cameras and the laser scanner. Visual inspection is based on convolutional neural networks, which support the creation of high-level discriminative features for complex non-linear pattern classification. Then, real-time 3D information is accurately calculated and the crack position and orientation is passed to the robotic platform. The entire system has been evaluated in railway and road tunnels, i.e. in Egnatia Highway and London underground infrastructure.

  16. Quantum Tunneling Affects Engine Performance.

    Science.gov (United States)

    Som, Sibendu; Liu, Wei; Zhou, Dingyu D Y; Magnotti, Gina M; Sivaramakrishnan, Raghu; Longman, Douglas E; Skodje, Rex T; Davis, Michael J

    2013-06-20

    We study the role of individual reaction rates on engine performance, with an emphasis on the contribution of quantum tunneling. It is demonstrated that the effect of quantum tunneling corrections for the reaction HO2 + HO2 = H2O2 + O2 can have a noticeable impact on the performance of a high-fidelity model of a compression-ignition (e.g., diesel) engine, and that an accurate prediction of ignition delay time for the engine model requires an accurate estimation of the tunneling correction for this reaction. The three-dimensional model includes detailed descriptions of the chemistry of a surrogate for a biodiesel fuel, as well as all the features of the engine, such as the liquid fuel spray and turbulence. This study is part of a larger investigation of how the features of the dynamics and potential energy surfaces of key reactions, as well as their reaction rate uncertainties, affect engine performance, and results in these directions are also presented here.

  17. Pharmacotherapy of carpal tunnel syndrome.

    Science.gov (United States)

    de Pablo, Paola; Katz, Jeffrey N

    2003-06-01

    Carpal tunnel syndrome (CTS) is the most common peripheral nerve entrapment syndrome. CTS is a compression neuropathy caused by elevated pressure in the carpal tunnel. CTS has the potential to substantially limit performance of activities of daily living for some individuals. The goal of therapy for CTS is to improve symptoms and reduce signs of the disease, as well as prevent progression and loss of hand function. There are several treatment alternatives to relieve the pressure on the median nerve, both surgical and conservative. The most common measures employed in the initial treatment of CTS are NSAIDs, local and systemic corticosteroids, diuretics and pyridoxine. However, CTS treatment usually includes a combination of pharmacotherapy with other strategies such as splinting and activity modification. Injections of corticosteroids into the carpal tunnel are often employed for cases not responding to conservative treatment. Surgery is superior to conservative therapies for most persistently symptomatic patients. The aim of this paper is to review the pharmacological agents used for relieving the symptoms of CTS.

  18. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  19. Variable Density Turbulence Tunnel Facility

    CERN Document Server

    Bewley, Gregory P; Sinhuber, Michael; Xu, Haitao; Bodenschatz, Eberhard

    2014-01-01

    The Variable Density Turbulence Tunnel (VDTT) at the Max Planck Institute for Dynamics and Self-Organization in G\\"ottingen, Germany produces very high turbulence levels at moderate flow velocities, low power consumption and adjustable kinematic viscosity. To reach the highest Reynolds number, the tunnel can be filled and pressurized up to 15 bar with the dense gas sulfur hexafluoride (SF$_6$). The Reynolds number can be varied by changing the pressure or flow rate of the gas or by using different non-flammable gases including air. Turbulence is generated at the upstream ends of two measurement sections with grids, and the evolution of this turbulence is observed as it moves down the length of the sections. We describe the instrumentation presently in operation, which consists of the tunnel itself, classical grid turbulence generators, and state-of-the-art nano-fabricated hot-wire anemometers provided by Princeton University [Vallikivi et al. (2011) Exp. Fluids 51, 1521]. We report measurements of the charact...

  20. Tunneling Dynamics Between Atomic Bright Solitons

    CERN Document Server

    Zhao, Li-Chen; Yang, Zhan-Ying; Yang, Wen-Li

    2016-01-01

    We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$.

  1. Investigation into scanning tunnelling luminescence microscopy

    CERN Document Server

    Manson-Smith, S K

    2001-01-01

    This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provi...

  2. Tunnel design considering stress release effect

    Institute of Scientific and Technical Information of China (English)

    Van-hung DAO

    2009-01-01

    In tunnel design,the determination of installation time and the stiffness of supporting structures is very important to the tunnel stability.This study used the convergence-confinement method to determine the stress and displacement of the tunnel while considering the counter-pressure curve of the ground base,the stress release effect,and the interaction between the tunnel lining and the rock surrounding the tunnel chamber.The results allowed for the determination of the installation time,distribution and strength of supporting structures.This method was applied to the intake tunnel in the Ban Ve Hydroelectric Power Plant,in Nghe An Province,Vietnam.The results show that when a suitable displacement u0 ranging from 0.0865 m to 0.0919 m occurrs,we can install supporting structures that satisfy the stability and economical requirements.

  3. RITD – Wind tunnel testing

    Science.gov (United States)

    Haukka, Harri; Harri, Ari-Matti; Aleksashkin, Sergei; Koryanov, Valeri; Schmidt, Walter; Heilimo, Jyri; Finchenko, Valeri; Martynov, Maxim; Ponomarenko, Andrey; Kazakovtsev, Victor; Arruego, Ignazio

    2015-04-01

    An atmospheric re-entry and descent and landing system (EDLS) concept based on inflatable hypersonic decelerator techniques is highly promising for the Earth re-entry missions. We developed such EDLS for the Earth re-entry utilizing a concept that was originally developed for Mars. This EU-funded project is called RITD - Re-entry: Inflatable Technology Development - and it was to assess the bene¬fits of this technology when deploying small payloads from low Earth orbits to the surface of the Earth with modest costs. The principal goal was to assess and develope a preliminary EDLS design for the entire relevant range of aerodynamic regimes expected to be encountered in Earth's atmosphere during entry, descent and landing. The RITD entry and descent system utilizes an inflatable hypersonic decelerator. Development of such system requires a combination of wind tunnel tests and numerical simulations. This included wind tunnel tests both in transsonic and subsonic regimes. The principal aim of the wind tunnel tests was the determination of the RITD damping factors in the Earth atmosphere and recalculation of the results for the case of the vehicle descent in the Mars atmosphere. The RITD mock-up model used in the tests was in scale of 1:15 of the real-size vehicle as the dimensions were (midsection) diameter of 74.2 mm and length of 42 mm. For wind tunnel testing purposes the frontal part of the mock-up model body was manufactured by using a PolyJet 3D printing technology based on the light curing of liquid resin. The tail part of the mock-up model body was manufactured of M1 grade copper. The structure of the mock-up model placed th center of gravity in the same position as that of the real-size RITD. The wind tunnel test program included the defining of the damping factor at seven values of Mach numbers 0.85; 0.95; 1.10; 1.20; 1.25; 1.30 and 1.55 with the angle of attack ranging from 0 degree to 40 degrees with the step of 5 degrees. The damping characteristics of

  4. Goniometria da articulação tíbio-tarsal após imobilização temporária com fixador esquelético externo em cães

    OpenAIRE

    Alievi Marcelo Meller; Schossler João Eduardo; Teixeira Marcelo Weinsten

    2004-01-01

    Neste experimento, foram utilizados 10 cães clinicamente sadios, submetidos à imobilização temporária das articulações tíbio-tarsal, intertarsal e tarso-metatarsiana direita com fixador esquelético externo, tendo por objetivo avaliar através da mensuração da flexão, da extensão e da amplitude articular os danos provocados por esta imobilização. O aparelho de fixação esquelética externa manteve a articulação em um ângulo aproximado de 135masculine e permaneceu por 45 dias. Os animais apresenta...

  5. COMPARISON TRADITIONAL SYSTEMS OF TUNNEL FORMWORK SYSTEM

    OpenAIRE

    ERKAN, İbrahim Hakkı; Yılmaz, Ülkü Sultan; Türken, Hakan

    2011-01-01

    Tunnel formwork systems became the most widespread construction technology preferred in recent years in Turkey due to rapidity and economy. In this study, before all else, a brief information was given about the types and construction techniques of tunnel formwork systems. Then a reinforced concrete building sample was firstly modeled as it was constructed with the tunnel formwork system and secondly modeled as it was formed by a frame system with shear walls constructed by the traditional re...

  6. Quantum tunneling and field electron emission theories

    CERN Document Server

    Liang, Shi-Dong

    2013-01-01

    Quantum tunneling is an essential issue in quantum physics. Especially, the rapid development of nanotechnology in recent years promises a lot of applications in condensed matter physics, surface science and nanodevices, which are growing interests in fundamental issues, computational techniques and potential applications of quantum tunneling. The book involves two relevant topics. One is quantum tunneling theory in condensed matter physics, including the basic concepts and methods, especially for recent developments in mesoscopic physics and computational formulation. The second part is the f

  7. Electromyographic diagnosis of the carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    K. Toyonaga

    1978-06-01

    Full Text Available Sensory conduction velocities of the median nerVe were studied from digit to palm and from palm to wrist in normal subjects and in patients with the carpal tunnel syndrome. Definite slowing was noted in the palm to wrist segment, even in the early carpal tunnel syndrome. It was noted that 37% of normal women over 40 years of age had electrophysiological evidence of the carpal tunnel syndrome.

  8. Low-Frequency Electromagnetic Backscattering from Tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Casey, K; Pao, H

    2007-01-16

    Low-frequency electromagnetic scattering from one or more tunnels in a lossy dielectric half-space is considered. The tunnel radii are assumed small compared to the wavelength of the electromagnetic field in the surrounding medium; a tunnel can thus be modeled as a thin scatterer, described by an equivalent impedance per unit length. We examine the normalized backscattering width for cases in which the air-ground interface is either smooth or rough.

  9. Raynaud's syndrome and carpal tunnel syndrome.

    OpenAIRE

    Waller, D G; Dathan, J R

    1985-01-01

    We report three cases of Raynaud's syndrome with digital ischaemic ulceration, in association with carpal tunnel syndrome. In all cases, the aetiology of the Raynaud's syndrome was probably unrelated to the nerve compression. However, symptoms were worse on the side of the median nerve lesion in two patients and worse on the side with the most severe nerve dysfunction in the third; symptoms were relieved by carpal tunnel decompression in two patients. We suggest that carpal tunnel syndrome ma...

  10. Predictive modelling of ferroelectric tunnel junctions

    Science.gov (United States)

    Velev, Julian P.; Burton, John D.; Zhuravlev, Mikhail Ye; Tsymbal, Evgeny Y.

    2016-05-01

    Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device functionality. Switching the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance effect. From a fundamental perspective, ferroelectric tunnel junctions and their version with ferromagnetic electrodes, i.e., multiferroic tunnel junctions, are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on transport. From a practical perspective, ferroelectric tunnel junctions hold promise for disruptive device applications. In a very short time, they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive readout. This remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental effort. In this review article, we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental work. We discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

  11. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco

    2011-01-01

    durability provisions, commitment to environmental aspects, issues of sustainability and safety assurance, for their whole lifecycle. The design for safety of tunnel infrastructures is a multifaceted process, since there are many aspects that need to be accounted for, regarding different aspects (e...... for upgrading fire safety provisions and tunnel management are also important for existing tunnels. In this study, following a brief introduction of issues regarding the above mentioned aspects, the structural performance of a steel rib for a tunnel infrastructure subject to fire is assessed by means...

  12. Surgical efficacy of carpal tunnel release for carpal tunnel syndrome in acromegaly: report of four patients.

    Science.gov (United States)

    Iwasaki, N; Masuko, T; Ishikawa, J; Minami, A

    2005-12-01

    Although carpal tunnel syndrome is frequent in acromegaly, few acromegalics will be encountered by most hand surgeons. This paper considers the treatment of four cases of acromegaly in whom carpal tunnel syndrome arose, to discuss aspects of management of carpal tunnel syndrome in this patient group.

  13. Acute Bronchitis

    Science.gov (United States)

    Bronchitis is an inflammation of the bronchial tubes, the airways that carry air to your lungs. It ... chest tightness. There are two main types of bronchitis: acute and chronic. Most cases of acute bronchitis ...

  14. Bronchitis - acute

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001087.htm Bronchitis - acute To use the sharing features on this page, please enable JavaScript. Acute bronchitis is swelling and inflamed tissue in the main ...

  15. Percutaneous Creation of Bare Intervascular Tunnels for Salvage of Thrombosed Hemodialysis Fistulas Without Recanalizable Outflow

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Matt Chiung-Yu, E-mail: jjychen@gmail.com [Yuan’s General Hospital, Department of Interventional Radiology (China); Wang, Yen-Chi [E-Da Hospital, Department of Radiology (China); Weng, Mei-Jui [Kaohsiung Veterans General Hospital, Department of Radiology (China)

    2015-08-15

    PurposeThis study aimed to retrospectively assess the efficacy of a bare intervascular tunnel for salvage of a thrombosed hemodialysis fistula. We examined the clinical outcomes and provided follow-up images of the bare intervascular tunnel.Materials and MethodsEight thrombosed fistulas lacked available recanalizable outflow veins were included in this study. These fistulas were salvaged by re-directing access site flow to a new outflow vein through a percutaneously created intervascular tunnel without stent graft placement. The post-intervention primary and secondary access patency rates were calculated using the Kaplan–Meier method.ResultsThe procedural and clinical success rates were 100 %. Post-intervention primary and secondary access patency at 300 days were 18.7 ± 15.8 and 87.5 ± 11.7 %, respectively. The mean follow-up period was 218.7 days (range 10–368 days). One patient died of acute myocardial infarction 10 days after the procedure. No other major complications were observed. Minor complications, such as swelling, ecchymosis, and pain around the tunnel, occurred in all of the patients.ConclusionsPercutaneous creation of a bare intervascular tunnel is a treatment option for thrombosed hemodialysis fistulas without recanalizable outflow in selected patients.

  16. Tunneling electroresistance of MgZnO-based tunnel junctions

    Science.gov (United States)

    Belmoubarik, Mohamed; Al-Mahdawi, Muftah; Obata, Masao; Yoshikawa, Daiki; Sato, Hideyuki; Nozaki, Tomohiro; Oda, Tatsuki; Sahashi, Masashi

    2016-10-01

    We investigated the tunneling electroresistance (TER) in metal/wurtzite-MgZnO/metal junctions for applications in nonvolatile random-access memories. A resistive switching was detected utilizing an electric-field cooling at ±1 V and exhibited a TER ratio of 360%-490% at 2 K. The extracted change in the average barrier height between the two resistance states gave an estimation of the MgZnO electric polarization at 2.5 μC/cm2 for the low-temperature limit. In addition, the temperature-dependent TER ratio and the shift of the localized states energies at the barrier interface supported the ferroelectric behavior of the MgZnO tunnel-barrier. From the first-principles calculations, we found a similar effect of the barrier height change coming from the reversal of ZnO electric polarization. The possibility of using metal electrodes and lower growth temperatures, in addition to the ferroelectric property, make the ZnO-based memory devices suitable for CMOS integration.

  17. More about tunnelling times and superluminal tunnelling (Hartmann effect)

    Energy Technology Data Exchange (ETDEWEB)

    Olkhovsky, V.S. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Research]|[INFN-Sezione di Catania (Italy); Recami, E. [Bergamo Univ. (Italy). Facolta` di Ingegneria]|[State Univ. at Campinas, Campinas (Brazil); Raciti, F. [Catania Univ. (Italy); Zaichenko, A. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Reserch

    1995-05-01

    Aims of the present paper are: (i) presenting and analysing the results of various numerical calculations on the penetration and return times <{tau}{sub Pen}>, <{tau}{sub Ret}>, during tunnelling inside a rectangular potential barrier, for various penetration depths x{sub f}; (ii) putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) D{sub {tau}T} and D{sub {tau}R} for the time durations of transmission and reflection processes; (iii) mentioning, moreover, that our definition <{tau}{sub T}> for the average transmission time results to constitute an improvement of the ordinary dwell- time formula; (iv) commenting, at last, on the basis of the new numerical results, upon some recent criticism by C.R. Leavens. The paper stresses that numerical evaluations confirm that the approach implied, and implies, the existence of the Hartmann effect: an effect that in these days (due to the theoretical connections between tunnelling and evanescent-wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna - indirect, but quite interesting, experimental verification.

  18. Tunneling without barriers with gravity

    CERN Document Server

    Kanno, Sugumi; Soda, Jiro

    2012-01-01

    We consider the vacuum decay of the flat Minkowski space to an anti-de Sitter space. We find a one-parameter family of potentials that allow exact, analytical instanton solutions describing tunneling without barriers in the presence of gravity. In the absence of gravity such instantons were found and discussed by Lee and Weinberg more than a quarter of a century ago. The bounce action is also analytically computed. We discuss possible implications of these new instantons to cosmology in the context of the string theory landscape.

  19. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

    The essays in this book deal with of the problem of quantum tunnelling and related behavior of a microscopic or macroscopic system, which interacts strongly with an ""environment"" - this being some form of condensed matter. The ""system"" in question need not be physically distinct from its environment, but could, for example, be one particular degree of freedom on which attention is focussed, as in the case of the Josephson junction studied in several of the papers. This general problem has been studied in many hundreds, if not thousands, of articles in the literature, in contexts as diverse

  20. Dynamical tunneling in optical cavities

    CERN Document Server

    Hackenbroich, G; Hackenbroich, Gregor; Noeckel, Jens U.

    1998-01-01

    The lifetime of whispering gallery modes in a dielectric cavity with a metallic inclusion is shown to fluctuate by orders of magnitude when size and location of the inclusion are varied. We ascribe these fluctuations to tunneling transitions between resonances quantized in different regions of phase space. This interpretation is confirmed by a comparison of the classical phase space structure with the Husimi distribution of the resonant modes. A model Hamiltonian is introduced that describes the phenomenon and shows that it can be expected in a more general class of systems.

  1. Full-Scale Tunnel (FST)

    Science.gov (United States)

    1929-01-01

    Modified propeller and spinner in Full-Scale Tunnel (FST) model. On June 26, 1929, Elton W. Miller wrote to George W. Lewis proposing the construction of a model of the full-scale tunnel. 'The excellent energy ratio obtained in the new wind tunnel of the California Institute of Technology suggests that before proceeding with our full scale tunnel design, we ought to investigate the effect on energy ratio of such factors as: 1. small included angle for the exit cone; 2. carefully designed return passages of circular section as far as possible, without sudden changes in cross sections; 3. tightness of walls. It is believed that much useful information can be obtained by building a model of about 1/16 scale, that is, having a closed throat of 2 ft. by 4 ft. The outside dimensions would be about 12 ft. by 25 ft. in plan and the height 4 ft. Two propellers will be required about 28 in. in diameter, each to be driven by direct current motor at a maximum speed of 4500 R.P.M. Provision can be made for altering the length of certain portions, particularly the exit cone, and possibly for the application of boundary layer control in order to effect satisfactory air flow. This model can be constructed in a comparatively short time, using 2 by 4 framing with matched sheathing inside, and where circular sections are desired they can be obtained by nailing sheet metal to wooden ribs, which can be cut on the band saw. It is estimated that three months will be required for the construction and testing of such a model and that the cost will be approximately three thousand dollars, one thousand dollars of which will be for the motors. No suitable location appears to exist in any of our present buildings, and it may be necessary to build it outside and cover it with a roof.' George Lewis responded immediately (June 27) granting the authority to proceed. He urged Langley to expedite construction and to employ extra carpenters if necessary. Funds for the model came from the FST project

  2. Metal-Vacuum-Metal Tunneling

    Science.gov (United States)

    1990-11-01

    the unexposed areas was removed with wet etchants. The Al lines formed in this way were 1000 A in width. The field emission mode was also used by...positioned close to the substrate within tunneling range. Whey they ramped the tip voltage to 10-20 volts they formed patterns on the substrate that were...associated with the light induced decomposition of III-V compounds. It is based on well-known work on photo- oxidation and the anisotropic etching of III-V

  3. Computational Wind Tunnel: A Design Tool for Rotorcraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Rotorcraft engineers traditionally use the wind tunnel to evaluate and finalize designs. Insufficient correlation between wind tunnel results and flight tests, have...

  4. Acute pancreatitis

    Directory of Open Access Journals (Sweden)

    Bo-Guang Fan

    2010-01-01

    Full Text Available Background : Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims : The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods : We reviewed the English-language literature (Medline addressing pancreatitis. Results : Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingestion. There are a number of important issues regarding clinical highlights in the classification, treatment and prognosis of acute pancreatitis, and treatment options for complications of acute pancreatitis including pancreatic pseudocysts. Conclusions : Multidisciplinary approach should be used for the management of the patient with acute pancreatitis.

  5. Acute pancreatitis

    Directory of Open Access Journals (Sweden)

    Bo-Guang Fan

    2010-05-01

    Full Text Available Background: Acute pancreatitis continues to be a serious illness, and the patients with acute pancreatitis are at risk to develop different complications from ongoing pancreatic inflammation. Aims: The present review is to highlight the classification, treatment and prognosis of acute pancreatitis. Material & Methods: We reviewed the English-language literature (Medline addressing pancreatitis. Results: Acute pancreatitis is frequently caused by gallstone disease or excess alcohol ingestion. There are a number of important issues regarding clinical highlights in the classification, treatment and prognosis of acute pancreatitis, and treatment options for complications of acute pancreatitis including pancreatic pseudocysts. Conclusions: Multidisciplinary approach should be used for the management of the patient with acute pancreatitis.

  6. Transport of dangerous goods through road tunnels

    DEFF Research Database (Denmark)

    Jørgensen, N O; Lacroix, Didier; Amundsen, F.H.;

    1999-01-01

    A paper which describes the work of an OECD research group. The group has suggested a grouping of dangerous materials, a quantitative risk assessment model and a decision support model which should allow tunnel operators to determine if a given material should be allowed throug a given tunnel...

  7. Virtual Processes and Quantum Tunnelling as Fictions

    Science.gov (United States)

    Arthur, Richard T. W.

    2012-01-01

    In this paper it is argued that virtual processes are dispensable fictions. The argument proceeds by a comparison with the phenomenon of quantum tunnelling. Building on an analysis of Levy-Leblond and Balibar, it is argued that, although the phenomenon known as quantum tunnelling certainly occurs and is at the basis of many paradigmatic quantum…

  8. Superconducting Super Collider Laboratory : tunnel boring

    CERN Multimedia

    SSC Media Production

    1999-01-01

    This film will take you down into the tunnel, show you the technology involved in boring the tunnel, and show what the SSC fmeans to the U.S. in terms of scientific discovery, innovative collaborations with industry and stimulating the job base nation-wide.

  9. 78 FR 46117 - National Tunnel Inspection Standards

    Science.gov (United States)

    2013-07-30

    ... September of 2009, and is another activity that FHWA conducted in partnership with AASHTO and NCHRP to... on this measure was a little over 24 months (2.05 years). \\11\\ The definition of a highway tunnel..., including tribally and federally owned tunnels. 650.505 Definitions At-grade Roadway. A definition for at...

  10. A Supermagnetic Tunnel Full of Subatomic Action

    CERN Multimedia

    2008-01-01

    Last year, before the gigantic hadron supercollider at CERN research facility was installed underground, a photographer captured this picture of a 1,950 metric ton tunnel containing giant magnets that will be placed in a tunnel and kept at near-zero temperatures.

  11. Ultrasonographic assessment of carpal tunnel biomechanics

    NARCIS (Netherlands)

    van Doesburg, M.H.M.

    2012-01-01

    In this thesis, we searched for a way to assess flexor tendon and median nerve biomechanics, as well as subsynovial connective tissue thickness (SSCT) in the carpal tunnel with ultrasound, and tried to see if these patterns would give a clue towards understanding the etiology of carpal tunnel syndro

  12. Prediction of swelling rocks strain in tunneling

    Science.gov (United States)

    Parsapour, D.; Fahimifar, A.

    2016-05-01

    Swelling deformations leading to convergence of tunnels may result in significant difficulties during the construction, in particular for long term use of tunnels. By extracting an experimental based explicit analytical solution for formulating swelling strains as a function of time and stress, swelling strains are predicted from the beginning of excavation and during the service life of tunnel. Results obtained from the analytical model show a proper agreement with experimental results. This closed-form solution has been implemented within a numerical program using the finite element method for predicting time-dependent swelling strain around tunnels. Evaluating effects of swelling parameters on time-dependent strains and tunnel shape on swelling behavior around the tunnel according to this analytical solution is considered. The ground-support interaction and consequent swelling effect on the induced forces in tunnel lining is considered too. Effect of delay in lining installation on swelling pressure which acting on the lining and its structural integrity, is also evaluated. A MATLAB code of " SRAP" is prepared and applied to calculate all swelling analysis around tunnels based on analytical solution.

  13. Energy saving in tunnel entrance lighting.

    NARCIS (Netherlands)

    Schreuder, D.A. & Swart, L.

    1993-01-01

    Tunnel entrances may present themselves during the day as a "black hole" in which no details can be perceived. In order to ensure safe and comfortable driving at high speeds, the entrance zone must be lit to a high luminance level. Modern tunnel lighting technology is focused on two aspects: (1

  14. Colloquium: Time-resolved scanning tunneling microscopy

    NARCIS (Netherlands)

    Houselt, van Arie; Zandvliet, Harold J.W.

    2010-01-01

    Scanning tunneling microscopy has revolutionized our ability to image, study, and manipulate solid surfaces on the size scale of atoms. One important limitation of the scanning tunneling microscope (STM) is, however, its poor time resolution. Recording a standard image with a STM typically takes abo

  15. Flow-based detection of DNS tunnels

    NARCIS (Netherlands)

    Ellens, W.; Zuraniewski, P.W.; Sperotto, A.; Schotanus, H.A.; Mandjes, M.; Meeuwissen, H.B.

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  16. Flow-Based Detection of DNS Tunnels

    NARCIS (Netherlands)

    Ellens, W.; Żuraniewski, P.; Sperotto, A.; Schotanus, H.; Mandjes, M.; Meeuwissen, E.

    2013-01-01

    DNS tunnels allow circumventing access and security policies in firewalled networks. Such a security breach can be misused for activities like free web browsing, but also for command & control traffic or cyber espionage, thus motivating the search for effective automated DNS tunnel detection techniq

  17. Spin-valley filter and tunnel magnetoresistance in asymmetrical silicene magnetic tunnel junctions

    Science.gov (United States)

    Wang, Dali; Huang, Zeyuan; Zhang, Yongyou; Jin, Guojun

    2016-05-01

    The spin and valley transports and tunnel magnetoresistance are studied in a silicene-based asymmetrical magnetic tunnel junction consisting of a ferromagnetic tunnel barrier, sandwiched between a ferromagnetic electrode and a normal electrode. For such an asymmetrical silicene junction, a general formulism is established. The numerical results show that the spin-valley resolved conductances strongly depend on the magnetization orientation of the ferromagnetic tunnel barrier, and the fully spin-valley polarized current can be realized by tuning a perpendicularly applied electric field. We also find that the tunnel magnetoresistance in this case can be effectively modified by the external electric field when the conductance is fully spin-valley polarized. In particular, the exchange field in the ferromagnetic electrode can further substantially enhance the tunnel magnetoresistance of the system. Our work provides a practical method for electric and magnetic manipulation of valley/spin polarization and tunnel magnetoresistance.

  18. [Carpal tunnel syndrome. Current approaches].

    Science.gov (United States)

    Kouyoumdjian, J A

    1999-06-01

    A clinical, epidemiological and nerve conduction studies report on carpal tunnel syndrome was done after electrophysiological author's experience on 668 cases and literature review. The median nerve underwent focal (nodal) or segmental demyelination after compression on carpal tunnel, 3-4 distal to wrist fold. The symptomatic complex includes nocturnal hands numbness and paraesthesia, mostly bilateral and between 40-60 years old. Familial cases are described and the gene could encode thick transverse carpal ligament. Anthropomorphic findings could also bring about an additional risk, but with low significance. Magnetic resonance could be a useful tool for selected atypical cases. Conservative treatment and controversies on surgery timing are discussed. Classical conduction studies on median nerve reveal a prolonged distal segmental sensory latency and also on distal motor latency. Increasing sensitivity may be reach using additional methods such as, median mixed mid-palm latency, comparative mid-palm latency median/ulnar, comparative sensory latency median/radial and median/ulnar, inching method from wrist to palm recording on index/middle finger and comparative motor median/ulnar recording on lumbrical/interosseous muscle.

  19. Temporary closure of the tunnel

    CERN Document Server

    Relations with the Host States Service

    2005-01-01

    Owing to major maintenance work, the tunnel linking the various parts of the CERN site will be closed from Monday 4 July to Sunday 24 July 2005 The Host State authorities have given authorisation for persons employed by CERN or the Institutes to travel and for goods belonging to these entities to be transported between the various parts of the site via Gate E (Charles de Gaulle) while this work is being carried out, subject to strict compliance with the Rules for the Use of the Tunnel (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/8200980415.pdf). Gate E will thus be open between 7.00 a.m. and 7.00 p.m. from Monday to Friday during the period concerned. The rules governing the use of Gate E to enter the Meyrin site between 7.30 a.m. and 9.00 a.m. or to leave the site between 5.00 p.m. and 6.30 p.m. (see http://dsu.web.cern.ch/dsu/dsum/hsr/DOCUMENTS/12222_041027.pdf)) will remain unaffected by this temporary authorisation. Relations with the Host States Service and TS-FM Group

  20. CARPAL TUNNEL SYNDROME IN CYCLISTS

    Science.gov (United States)

    Sousa, Daniel; Sassul, Nicolás

    2017-01-01

    Objectives: About a group of cyclists, professionals / amateurs, Mountain bike, road and triathlon; achieve a good diagnosis of the disease, with a good clinical examination and sectorized according EGM injury evoked potentials. Methods: Clinical examination and accurate test with different signs of pathology. EGM with evocative potential and conduction velocity. Results: After 25 track cyclists, 18 professionals, 22 male and 3 female; for 24 months. Through good clinical examination and EMG. We got that 70% had direct compression injuries Carpal tunnel for poor support on the handlebars. The rest were cervical praxis, by poor body position on the bike, taking cervico very steep angles / dorsal, during competitions or training for more than 2 hrs. Conclusion: A good prevention work with our teacher / cyclist in the position of deposrtista in ciclo simulador. Work in the gym, on tone and elongation of the upper limb. A good EGM, made with a specialist physiatrist. It leads to the correct diagnosis, leads to a good final treatment; which agreed that:* Cervical praxis, had good results with treatment Conservative / FST / vit.B12.* The Carpal tunnel own injuries, treatment was quirúrg. (Open surgery) with subsequent FST / vit..B12 with satisfactory return in time to sporting activity.

  1. IPv6 Tunneling Over IPV4

    Directory of Open Access Journals (Sweden)

    A.Sankara Narayanan

    2012-03-01

    Full Text Available Due to the huge growth of the internet users, mobile users using internet connection makes development and implementation of IPv6 as an alternate solution. IPv6 is a long anticipated upgrade to the internets main communication protocol, which is called IPv4. The current address space provided by IPv4, with only4, 294, 967, 296 addresses. Nowadays IPv6 tunneling over IPv4 are widely used to form the global IPv6 Internet. The IPv6 128-bit address scheme it should provide enough addresses for everyones computer. Tunneling provides a path to use an existing IPv4 to IPv6. This paper describes typical IPv6 tunneling and tunnel brokers deployment in real IP networks. In the deployment of IPv6, it is a well adopted practice that IPv6 networks are interconnected via IPv6 over IPv4 (IPv6/IPv4 tunnels.

  2. Characterization of magnetic tunnel junction test pads

    DEFF Research Database (Denmark)

    Østerberg, Frederik Westergaard; Kjær, Daniel; Nielsen, Peter Folmer

    2015-01-01

    We show experimentally as well as theoretically that patterned magnetic tunnel junctions can be characterized using the current-in-plane tunneling (CIPT) method, and the key parameters, the resistance-area product (RA) and the tunnel magnetoresistance (TMR), can be determined. The CIPT method...... on square tunnel junction pads with varying sizes and analyze the measured data using both the original and the modified CIPT model. Thus, we determine in which sample size range the modified CIPT model is needed to ensure validity of the extracted sample parameters, RA and TMR. In addition, measurements...... as a function of position on a square tunnel junction pad are used to investigate the sensitivity of the measurement results to probe misalignment....

  3. Concept development for HLW disposal research tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Queon, S. K.; Kim, K. S.; Park, J. H.; Jeo, W. J.; Han, P. S. [KAERI, Taejon (Korea, Republic of)

    2003-10-01

    In order to dispose high-level radioactive waste in a geological formation, it is necessary to assess the safety of a disposal concept by excavating a research tunnel in the same geological formation as the host rock mass. The design concept of a research tunnel depends on the actual disposal concept, repository geometry, experiments to be carried at the tunnel, and geological conditions. In this study, analysis of the characteristics of the disposal research tunnel, which is planned to be constructed at KAERI site, calculation of the influence of basting impact on neighbor facilities, and computer simuation for mechanical stability analysis using a three-dimensional code, FLAC3D, had been carried out to develop the design concept of the research tunnel.

  4. Control of tunneling by adapted signals

    CERN Document Server

    Ivlev, B I

    2000-01-01

    Process of quantum tunneling of particles in various physical systems can be effectively controlled even by a weak and slow varying in time electromagnetic signal if to adapt specially its shape to a particular system. During an under-barrier motion of a particle such signal provides a "coherent" assistance of tunneling by the multi-quanta absorption resulting in a strong enhancement of the tunneling probability. The semiclassical approach based on trajectories in the complex time is developed for tunneling in a non-stationary field. Enhancement of tunneling occurs when a singularity of the signal coincides in position at the complex time plane with a singularity of the classical Newtonian trajectory of the particle. The developed theory is also applicable to the over-barrier reflection of particles and to reflection of classical waves (electromagnetic, hydrodynamic, etc.) from a spatially-smooth medium.

  5. Experimental evidence for Wigner's tunneling time

    CERN Document Server

    Camus, Nicolas; Fechner, Lutz; Klaiber, Michael; Laux, Martin; Mi, Yonghao; Hatsagortsyan, Karen Z; Pfeifer, Thomas; Keitel, Christoph H; Moshammer, Robert

    2016-01-01

    Tunneling of a particle through a potential barrier remains one of the most remarkable quantum phenomena. Owing to advances in laser technology, electric fields comparable to those electrons experience in atoms are readily generated and open opportunities to dynamically investigate the process of electron tunneling through the potential barrier formed by the superposition of both laser and atomic fields. Attosecond-time and angstrom-space resolution of the strong laser-field technique allow to address fundamental questions related to tunneling, which are still open and debated: Which time is spent under the barrier and what momentum is picked up by the particle in the meantime? In this combined experimental and theoretical study we demonstrate that for strong-field ionization the leading quantum mechanical Wigner treatment for the time resolved description of tunneling is valid. We achieve a high sensitivity on the tunneling barrier and unambiguously isolate its effects by performing a differential study of t...

  6. Detecting DNS Tunnels Using Character Frequency Analysis

    CERN Document Server

    Born, Kenton

    2010-01-01

    High-bandwidth covert channels pose significant risks to sensitive and proprietary information inside company networks. Domain Name System (DNS) tunnels provide a means to covertly infiltrate and exfiltrate large amounts of information passed network boundaries. This paper explores the possibility of detecting DNS tunnels by analyzing the unigram, bigram, and trigram character frequencies of domains in DNS queries and responses. It is empirically shown how domains follow Zipf's law in a similar pattern to natural languages, whereas tunneled traffic has more evenly distributed character frequencies. This approach allows tunnels to be detected across multiple domains, whereas previous methods typically concentrate on monitoring point to point systems. Anomalies are quickly discovered when tunneled traffic is compared to the character frequency fingerprint of legitimate domain traffic.

  7. Snow and ice blocking of tunnels

    Energy Technology Data Exchange (ETDEWEB)

    Lia, Leif

    1998-12-31

    Hydroelectric power development in cold regions causes much concern about operational reliability and dam safety. This thesis studies the temperature distribution in tunnels by means of air temperature measurements in six tunnel spillways and five diversion tunnels. The measurements lasted for two consecutive winters. The air through flow tunnel is used as it causes cooling of both rock and water. In open spillway tunnels, frost reaches the entire tunnel. In spillway tunnels with walls, the frost zones reach about 100 m from the downstream end. In mildly-inclined diversion tunnels, a frost free zone is located in the middle of the tunnel and snow and ice problems were only observed in the inlet and outlet. Severe aufeis is accumulation is observed in the frost zones. The heat transfer from rock to air, water and ice is calculated and used in a prediction model for the calculation of aufeis build-up together with local field observation data. The water penetration of snow plugs is also calculated, based on the heat balance. It takes 20 to 50 days for water to enter the blocked tunnel. The empirical values are 30 to 60 days, but only 1 day if the temperature of the snow pack is 0{sup o}C. Sensitivity analyses are carried out for temperature variations in rock, snow, water and ice. Systematic field observation shows that it is important for hydropower companies to know about the effects of snow and ice blocking in an area. A risk analysis of dam safety is presented for a real case. Finally, the thesis proposes solutions which can reduce the snow and ice problems. 79 refs., 63 figs., 11 tabs.

  8. Analysis of Blast Wave Propagation Inside Tunnel

    Institute of Scientific and Technical Information of China (English)

    LIU Jingbo; YAN Qiushi; WU Jun

    2008-01-01

    The explosion inside tunnel would generate blast wave which transmits through the longi tudinal tunnel.Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure,blast wave propagation inside tunnel is distinguished from that in air.When the explosion happens inside tunnel,the overpressure peak is higher than that of explosion happening in air.The continuance time of the biast wave also becomes longer.With the help of the numerical simu lation finite element software LS-DYNA.a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out.LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems.Compared with the experimental results.the simulation results have made the material parameters of numerical simulation model available.By using the model and the same material parameters,many results were adopted by calculating the model under different TNT explosion dynamites.Then the method of dimensional analysis was Used for the Simulation resufts.AS Overpressures of the explosion biast wave are the governing factor in fhe tunnel responses.a formula for the explosion biast wave overpressure at a certain distance from the detonation center point inside the tunnel was de rived by using the dimensional analysis theory.By cornparing the results computed by the fromula with experimental results which were obtained before.the formula was proved to be very applicable at some instance.The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.

  9. Quantitative risk assessment modeling for nonhomogeneous urban road tunnels.

    Science.gov (United States)

    Meng, Qiang; Qu, Xiaobo; Wang, Xinchang; Yuanita, Vivi; Wong, Siew Chee

    2011-03-01

    Urban road tunnels provide an increasingly cost-effective engineering solution, especially in compact cities like Singapore. For some urban road tunnels, tunnel characteristics such as tunnel configurations, geometries, provisions of tunnel electrical and mechanical systems, traffic volumes, etc. may vary from one section to another. These urban road tunnels that have characterized nonuniform parameters are referred to as nonhomogeneous urban road tunnels. In this study, a novel quantitative risk assessment (QRA) model is proposed for nonhomogeneous urban road tunnels because the existing QRA models for road tunnels are inapplicable to assess the risks in these road tunnels. This model uses a tunnel segmentation principle whereby a nonhomogeneous urban road tunnel is divided into various homogenous sections. Individual risk for road tunnel sections as well as the integrated risk indices for the entire road tunnel is defined. The article then proceeds to develop a new QRA model for each of the homogeneous sections. Compared to the existing QRA models for road tunnels, this section-based model incorporates one additional top event-toxic gases due to traffic congestion-and employs the Poisson regression method to estimate the vehicle accident frequencies of tunnel sections. This article further illustrates an aggregated QRA model for nonhomogeneous urban tunnels by integrating the section-based QRA models. Finally, a case study in Singapore is carried out.

  10. Area and shape changes of the carpal tunnel in response to tunnel pressure.

    Science.gov (United States)

    Li, Zong-Ming; Masters, Tamara L; Mondello, Tracy A

    2011-12-01

    Carpal tunnel mechanics is relevant to our understanding of median nerve compression in the tunnel. The compliant characteristics of the tunnel strongly influence its mechanical environment. We investigated the distensibility of the carpal tunnel in response to tunnel pressure. A custom balloon device was designed to apply controlled pressure. Tunnel cross sections were obtained using magnetic resonance imaging to derive the relationship between carpal tunnel pressure and morphological parameters at the hook of hamate. The results showed that the cross-sectional area (CSA) at the level of the hook of hamate increased, on average, by 9.2% and 14.8% at 100 and 200 mmHg, respectively. The increased CSA was attained by a shape change of the cross section, displaying increased circularity. The increase in CSA was mainly attributable to the increase of area in the carpal arch region formed by the transverse carpal ligament. The narrowing of the carpal arch width was associated with an increase in the carpal arch. We concluded that the carpal tunnel is compliant to accommodate physiological variations of the carpal tunnel pressure, and that the increase in tunnel CSA is achieved by increasing the circularity of the cross section.

  11. Acute cholecystitis

    OpenAIRE

    Halpin, Valerie

    2014-01-01

    Acute cholecystitis causes unremitting right upper quadrant pain, anorexia, nausea, vomiting, and fever, and if untreated can lead to perforations, abscess formation, or fistulae. About 95% of people with acute cholecystitis have gallstones.It is thought that blockage of the cystic duct by a gallstone or local inflammation can lead to acute cholecystitis, but we don't know whether bacterial infection is also necessary.

  12. Direct Approach to Quantum Tunneling

    Science.gov (United States)

    Andreassen, Anders; Farhi, David; Frost, William; Schwartz, Matthew D.

    2016-12-01

    The decay rates of quasistable states in quantum field theories are usually calculated using instanton methods. Standard derivations of these methods rely in a crucial way upon deformations and analytic continuations of the physical potential and on the saddle-point approximation. While the resulting procedure can be checked against other semiclassical approaches in some one-dimensional cases, it is challenging to trace the role of the relevant physical scales, and any intuitive handle on the precision of the approximations involved is at best obscure. In this Letter, we use a physical definition of the tunneling probability to derive a formula for the decay rate in both quantum mechanics and quantum field theory directly from the Minkowski path integral, without reference to unphysical deformations of the potential. There are numerous benefits to this approach, from nonperturbative applications to precision calculations and aesthetic simplicity.

  13. Tunnel effect wave energy detection

    Science.gov (United States)

    Kaiser, William J. (Inventor); Waltman, Steven B. (Inventor); Kenny, Thomas W. (Inventor)

    1995-01-01

    Methods and apparatus for measuring gravitational and inertial forces, magnetic fields, or wave or radiant energy acting on an object or fluid in space provide an electric tunneling current through a gap between an electrode and that object or fluid in space and vary that gap with any selected one of such forces, magnetic fields, or wave or radiant energy acting on that object or fluid. These methods and apparatus sense a corresponding variation in an electric property of that gap and determine the latter force, magnetic fields, or wave or radiant energy in response to that corresponding variation, and thereby sense or measure such parameters as acceleration, position, particle mass, velocity, magnetic field strength, presence or direction, or wave or radiant energy intensity, presence or direction.

  14. Tunneling magnetoresistance of silicon chains

    Science.gov (United States)

    Matsuura, Yukihito

    2016-05-01

    The tunneling magnetoresistance (TMR) of a silicon chain sandwiched between nickel electrodes was examined by using first-principles density functional theory. The relative orientation of the magnetization in a parallel-alignment (PA) configuration of two nickel electrodes enhanced the current with a bias less than 0.4 V compared with that in an antiparallel-alignment configuration. Consequently, the silicon chain-nickel electrodes yielded good TMR characteristics. In addition, there was polarized spin current in the PA configuration. The spin polarization of sulfur atoms functioning as a linking bridge between the chain and nickel electrode played an important role in the magnetic effects of the electric current. Moreover, the hybridization of the sulfur 3p orbital and σ-conjugated silicon 3p orbital contributed to increasing the total current.

  15. Hawking Radiation and Classical Tunneling

    CERN Document Server

    Tracy, Eugene R

    2015-01-01

    Acoustic waves in fluids undergoing the transition from sub- to supersonic flow satisfy governing equations similar to those for light waves in the immediate vicinity of a black hole event horizon. This acoustic analogy has been used by Unruh and others as a conceptual model for `Hawking radiation.' Here we use variational methods, originally introduced by Brizard for the study of linearized MHD, and ray phase space methods, to analyze linearized acoustics in the presence of background flows. The variational formulation endows the evolution equations with natural Hermitian and symplectic structures that prove useful for later analysis. We derive a $2\\times 2$ normal form governing the wave evolution in the vicinity of the `event horizon.' This shows that the acoustic model can be reduced locally (in ray phase space) to a standard (scalar) tunneling process weakly coupled to a unidirectional non-dispersive wave (the `incoming wave'). Given the normal form, the Hawking `thermal spectrum' can be derived by invok...

  16. Theory of dissociative tunneling ionization

    CERN Document Server

    Svensmark, Jens; Madsen, Lars Bojer

    2016-01-01

    We present a theoretical study of the dissociative tunneling ionization process. Analytic expressions for the nuclear kinetic energy distribution of the ionization rates are derived. A particularly simple expression for the spectrum is found by using the Born-Oppenheimer (BO) approximation in conjunction with the reflection principle. These spectra are compared to exact non-BO ab initio spectra obtained through model calculations with a quantum mechanical treatment of both the electronic and nuclear degrees freedom. In the regime where the BO approximation is applicable imaging of the BO nuclear wave function is demonstrated to be possible through reverse use of the reflection principle, when accounting appropriately for the electronic ionization rate. A qualitative difference between the exact and BO wave functions in the asymptotic region of large electronic distances is shown. Additionally the behavior of the wave function across the turning line is seen to be reminiscent of light refraction. For weak fiel...

  17. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

    Full Text Available Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  18. Rudolf Hermann, wind tunnels and aerodynamics

    Science.gov (United States)

    Lundquist, Charles A.; Coleman, Anne M.

    2008-04-01

    Rudolf Hermann was born on December 15, 1904 in Leipzig, Germany. He studied at the University of Leipzig and at the Aachen Institute of Technology. His involvement with wind tunnels began in 1934 when Professor Carl Wieselsberger engaged him to work at Aachen on the development of a supersonic wind tunnel. On January 6, 1936, Dr. Wernher von Braun visited Dr. Hermann to arrange for use of the Aachen supersonic wind tunnel for Army problems. On April 1, 1937, Dr. Hermann became Director of the Supersonic Wind Tunnel at the Army installation at Peenemunde. Results from the Aachen and Peenemunde wind tunnels were crucial in achieving aerodynamic stability for the A-4 rocket, later designated as the V-2. Plans to build a Mach 10 'hypersonic' wind tunnel facility at Kochel were accelerated after the Allied air raid on Peenemunde on August 17, 1943. Dr. Hermann was director of the new facility. Ignoring destruction orders from Hitler as WWII approached an end in Europe, Dr. Hermann and his associates hid documents and preserved wind tunnel components that were acquired by the advancing American forces. Dr. Hermann became a consultant to the Air Force at its Wright Field in November 1945. In 1951, he was named professor of Aeronautical Engineering at the University of Minnesota. In 1962, Dr. Hermann became the first Director of the Research Institute at the University of Alabama in Huntsville (UAH), a position he held until he retired in 1970.

  19. Pair Tunneling through Single Molecules

    Science.gov (United States)

    Raikh, Mikhail

    2007-03-01

    Coupling to molecular vibrations induces a polaronic shift, and can lead to a negative charging energy, U. For negative U, the occupation of the ground state of the molecule is even. In this situation, virtual pair transitions between the molecule and the leads can dominate electron transport. At low temperature, T, these transitions give rise to the charge-Kondo effect [1]. We developed the electron transport theory through the negative-U molecule [2] at relatively high T, when the Kondo correlations are suppressed. Two physical ingredients distinguish our theory from the transport through a superconducting grain coupled to the normal leads [3]: (i) in parallel with sequential pair-tunneling processes, single-particle cotunneling processes take place; (ii) the electron pair on the molecule can be created (or annihilated) by two electrons tunneling in from (or out to) opposite leads. We found that, even within the rate-equation description, the behavior of differential conductance through the negative-U molecule as function of the gate voltage is quite peculiar: the height of the peak near the degeneracy point is independent of temperature, while its width is proportional to T. This is in contrast to the ordinary Coulomb-blockade conductance peak, whose integral strength is T-independent. At finite source-drain bias, V>>T, the width of the conductance peak is ˜V, whereas the conventional Coulomb-blockade peak at finite V splits into two sharp peaks at detunings V/2, and -V/2. Possible applications to the gate-controlled current rectification and switching will be discussed. [1] A. Taraphder and P. Coleman, Phys. Rev. Lett. 66, 2814 (1991). [2] J. Koch, M. E. Raikh, and F. von Oppen, Phys. Rev. Lett. 96, 056803 (2006). [3] F. W. J. Hekking, L. I. Glazman, K. A. Matveev, and R. I. Shekhter, Phys. Rev. Lett. 70, 4138 (1993).

  20. MUSCULOSKELETAL IMPAIRMENT IN PRYMARY HYPOTHYROIDISM.

    Science.gov (United States)

    Radu, Luliana; Groppa, Liliana; Vudu, Lorina

    2016-01-01

    This article contains bibliographical data concerning the rheumatic clinical manifestations in hypothyroidism: polyarthralgias, lack of recent skill of fine movements of the hands, carpal tunnel syndrome or tarsal, degenerative arthropathy or acute type (gout, chondrocalcinosis), adhesive capsulitis (frozen shoulder syndrome), generalized muscular stiffness, hypothyroid myopathy, secondary osteoarthritis, Dupuytren's contracture, "trigger finger" (also called as stenosing tenosynovitis or trigger thumb) etc. and data on the short history, epidemiology, of these disorders. Review include 60 bibliographical sources.

  1. Extraskeletal chondroma casuing carpal tunnel syndrome: A case report

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ok Hwa; Kim, Yeon Hee [Haeundae Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of)

    2014-03-15

    Carpal tunnel syndrome caused by extraskeletal chondroma has been scarcely reported in the literature. Authors report a case of carpal tunnel syndrome as a result of an extraskeletal chondroma arising within the carpal tunnel, and describe the radiological and pathological findings of the mass. We also discuss the differential diagnosis of the calcified space, occupying lesions that may occur in carpal tunnel.

  2. Pressure-morphology relationship of a released carpal tunnel.

    Science.gov (United States)

    Kim, Dong Hee; Marquardt, Tamara L; Gabra, Joseph N; Shen, Zhilei Liu; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2013-04-01

    We investigated morphological changes of a released carpal tunnel in response to variations of carpal tunnel pressure. Pressure within the carpal tunnel is known to be elevated in patients with carpal tunnel syndrome and dependent on wrist posture. Previously, increased carpal tunnel pressure was shown to affect the morphology of the carpal tunnel with an intact transverse carpal ligament (TCL). However, the pressure-morphology relationship of the carpal tunnel after release of the TCL has not been investigated. Carpal tunnel release (CTR) was performed endoscopically on cadaveric hands and the carpal tunnel pressure was dynamically increased from 10 to 120 mmHg. Simultaneously, carpal tunnel cross-sectional images were captured by an ultrasound system, and pressure measurements were recorded by a pressure transducer. Carpal tunnel pressure significantly affected carpal arch area (p 62 mm(2) at 120 mmHg. Carpal arch height, length, and width also significantly changed with carpal tunnel pressure (p carpal tunnel pressure increased, carpal arch height and length increased, but the carpal arch width decreased. Analyses of the pressure-morphology relationship for a released carpal tunnel revealed a nine times greater compliance than that previously reported for a carpal tunnel with an intact TCL. This change of structural properties as a result of transecting the TCL helps explain the reduction of carpal tunnel pressure and relief of symptoms for patients after CTR surgery.

  3. Band-to-Band Tunneling Transistors: Scalability and Circuit Performance

    Science.gov (United States)

    2013-05-01

    To better understand and evaluate tunnel field effect transistors (TFETs), a new TCAD analysis tool with dynamic nonlocal tunneling path...better understand and evaluate tunnel field effect transistors (TFETs), a new TCAD analysis tool with dynamic nonlocal tunneling path determination is...me complete my research with the best of practices. As a perennial procrastinator , my dissertation committee, Prof. Paul Wright, Prof. Sayeef

  4. The Thames Tideway Tunnel (3/3)

    CERN Document Server

    CERN. Geneva

    2012-01-01

    Lecture 3: Insight into a pioneering project at the cutting edge of engineering: the upgrade to London’s failing sewerage system. With a growing population and heavier rainfall, the River Thames is regularly polluted in breach of European Directive requirements. Two new storage and transfer tunnels will run up to 85m deep under the river and will intercept and divert sewer overflows to a treatment facility in east London. The challenges faced by constructing a tunnel project of this size under the river and through London’s historic urban environment will set a new UK record for this type of tunnelling.

  5. HYDRAULIC RESEARCH OF AERATORS ON TUNNEL SPILLWAYS

    Institute of Scientific and Technical Information of China (English)

    RUAN Shi-ping; WU Jian-hua; WU Wei-wei; XI Ru-ze

    2007-01-01

    The selection of the configuration and size of an aerator was of importance for a tunnel spillway under the conditions of high speed flows. Experimental investigations were conducted on the effects of entrained air on the tunnel spillway in the Goupitan Project, based on the criterion of gravity similarity and the condition of aerated flow velocity of over 6 m/s, with physical models. The configurations of the aerators were presented of a larger bottom air concentration, to protect the tunnel spillway from cavitation as well as to see no water fills in the grooves.

  6. Application of Important Factors in Tunnel Projects

    Directory of Open Access Journals (Sweden)

    Siamak Bagherian

    2013-06-01

    Full Text Available The objective of this thesis is to improve the quality of the basis for making decisions about tender prices and budgets for tunnel projects by developing a model for the estimation of construction time and cost. The planning and constructing of extensions to existing road and railway networks is an ongoing mission of transport infrastructure development. For functional, aesthetic or environmental reasons, a large number of these extensions are planned as tunnels. In the planning and procurement phases of tunnel projects, numerous decisions have to be made in relation to the tender price and project budget.

  7. Carpal tunnel syndrome - anatomical and clinical correlations.

    Science.gov (United States)

    Iskra, Tomasz; Mizia, Ewa; Musial, Agata; Matuszyk, Aleksandra; Tomaszewski, Krzysztof A

    2013-01-01

    Carpal tunnel syndrome (CTS) is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed. Common symptoms of CTS involve the hand and result from compression of the median nerve within the carpal tunnel. In general, CTS develops when the tissues around the median nerve irritate or compress on the nerve along its course through the carpal tunnel, however often it is very difficult to determine cause of CTS. Proper treatment (conservative or surgical) usually can relieve the symptoms and restore normal use of the wrist and hand.

  8. Tunneling time, exit time and exit momentum in strong field tunnel ionization

    Energy Technology Data Exchange (ETDEWEB)

    Teeny, Nicolas

    2016-10-18

    Tunnel ionization belongs to the fundamental processes of atomic physics. It is still an open question when does the electron tunnel ionize and how long is the duration of tunneling. In this work we solve the time-dependent Schroedinger equation in one and two dimensions and use ab initio quantum calculations in order to answer these questions. Additionally, we determine the exit momentum of the tunnel ionized electron from first principles. We find out results that are different from the assumptions of the commonly employed two-step model, which assumes that the electron ionizes at the instant of electric field maximum with a zero momentum. After determining the quantum final momentum distribution of tunnel ionized electrons we show that the two-step model fails to predict the correct final momentum. Accordingly we suggest how to correct the two-step model. Furthermore, we determine the instant at which tunnel ionization starts, which turns out to be different from the instant usually assumed. From determining the instant at which it is most probable for the electron to enter the tunneling barrier and the instant at which it exits we determine the most probable time spent under the barrier. Moreover, we apply a quantum clock approach in order to determine the duration of tunnel ionization. From the quantum clock we determine an average tunneling time which is different in magnitude and origin with respect to the most probable tunneling time. By defining a probability distribution of tunneling times using virtual detectors we relate both methods and explain the apparent discrepancy. The results found have in general an effect on the interpretation of experiments that measure the spectra of tunnel ionized electrons, and specifically on the calibration of the so called attoclock experiments, because models with imprecise assumptions are usually employed in order to interpret experimental results.

  9. Acute nierschade

    NARCIS (Netherlands)

    Hageman, D.; Kooman, J.P.; Lance, M.D.; van Heurn, L.W.E.; Snoeijs, M.G.

    2012-01-01

    - 'Acute kidney injury' is modern terminology for a sudden decline in kidney function, and is defined by the RIFLE classification (RIFLE is an acronym for Risk, Injury, Failure, Loss and End-stage kidney disease).- Acute kidney injury occurs as a result of the combination of reduced perfusion in the

  10. Tunnel Waterproofing with Membranes Waterproofing at Senoko Cabele Tunnel in comparison with International Standards

    Institute of Scientific and Technical Information of China (English)

    Stefan Hotz

    2004-01-01

    Waterproofing of tunnels is and has always been a challenge, worldwide: Changing Geology with hardly predictable water inflow, limited space underground and only very little intervention opportunities once the tunnel is completed. This paper elaborates such challenges and focuses on the waterproofing solutions of mined tunnels with membranes. Different standards and approaches for the waterproofing system. In Singapore, a membrane waterproofing system is used for the shafts and adits at Senoko Cable Tunnel. The paper project specific waterproofing challenges and emphasizes on solution for them.

  11. Tunneling into quantum wires: Regularization of the tunneling Hamiltonian and consistency between free and bosonized fermions

    Science.gov (United States)

    Filippone, Michele; Brouwer, Piet W.

    2016-12-01

    Tunneling between a point contact and a one-dimensional wire is usually described with the help of a tunneling Hamiltonian that contains a δ function in position space. Whereas the leading-order contribution to the tunneling current is independent of the way this δ function is regularized, higher-order corrections with respect to the tunneling amplitude are known to depend on the regularization. Instead of regularizing the δ function in the tunneling Hamiltonian, one may also obtain a finite tunneling current by invoking the ultraviolet cutoffs in a field-theoretic description of the electrons in the one-dimensional conductor, a procedure that is often used in the literature. For the latter case, we show that standard ultraviolet cutoffs lead to different results for the tunneling current in fermionic and bosonized formulations of the theory, when going beyond leading order in the tunneling amplitude. We show how to recover the standard fermionic result using the formalism of functional bosonization and revisit the tunneling current to leading order in the interacting case.

  12. Construction of Foundation for 15-Foot Spin Tunnel

    Science.gov (United States)

    1934-01-01

    Completed foundation for the outer housing for the 15-Foot Spin Tunnel. Charles Zimmerman was given the assignment to design and build a larger spin tunnel that would supplant the 5-foot Vertical Wind Tunnel. Authorization to build the tunnel using funds from the Federal Public Works Administration (PWA) came in June 1933. Construction started in late winter 1934 and the tunnel was operational in April 1935. The initial construction costs were $64,000.

  13. Survey Of Wind Tunnels At Langley Research Center

    Science.gov (United States)

    Bower, Robert E.

    1989-01-01

    Report presented at AIAA 14th Aerodynamic Testing Conference on current capabilities and planned improvements at NASA Langley Research Center's major wind tunnels. Focuses on 14 major tunnels, 8 unique in world, 3 unique in country. Covers Langley Spin Tunnel. Includes new National Transonic Facility (NTF). Also surveys Langley Unitary Plan Wind Tunnel (UPWT). Addresses resurgence of inexpensive simple-to-operate research tunnels. Predicts no shortage of tools for aerospace researcher and engineer in next decade or two.

  14. Survey Of Wind Tunnels At Langley Research Center

    Science.gov (United States)

    Bower, Robert E.

    1989-01-01

    Report presented at AIAA 14th Aerodynamic Testing Conference on current capabilities and planned improvements at NASA Langley Research Center's major wind tunnels. Focuses on 14 major tunnels, 8 unique in world, 3 unique in country. Covers Langley Spin Tunnel. Includes new National Transonic Facility (NTF). Also surveys Langley Unitary Plan Wind Tunnel (UPWT). Addresses resurgence of inexpensive simple-to-operate research tunnels. Predicts no shortage of tools for aerospace researcher and engineer in next decade or two.

  15. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    Directory of Open Access Journals (Sweden)

    Omar Siddiqui

    2015-03-01

    Full Text Available We show that metallic wires embedded in narrow waveguide bends and channels demonstrate resonance behavior at specific frequencies. The electromagnetic energy at these resonances tunnels through the narrow waveguide channels with almost no propagation losses. Under the tunneling behavior, high-intensity electromagnetic fields are produced in the vicinity of the metallic wires. These intense field resonances can be exploited to build highly sensitive dielectric sensors. The sensor operation is explained with the help of full-wave simulations. A practical setup consisting of a 3D waveguide bend is presented to experimentally observe the tunneling phenomenon. The tunneling frequency is predicted by determining the input impedance minima through a variational formula based on the Green function of a probe-excited parallel plate waveguide.

  16. Hi-tech Tunnel Sets World Record

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A sport utility vehicle takes the new direct route from Xi’an, capital city of northwest China’s Shaanxi Province, to Zhashui County through the Zhongnanshan Tunnel, which opened on January 21.With a total investment of nearly 3.2 billion yuan, the four-lane highway is the world’s longest double-tube tunnel, stretching 18.02 km.As a major part of the province’s expressway network, the tunnel connects Xi’an with southwest Shaanxi through the Qinling Mountains, shortening the previous three-hour trip to 40 minutes.The highway tunnel is also planned as part of a national highway linking north China’s Inner Mongolia Autonomous Region and south China’s Guangxi Zhuang Autonomous Region.

  17. Control over Rectification in Supramolecular Tunneling Junctions

    NARCIS (Netherlands)

    Wimbush, K.S.; Wimbush, Kim S.; Reus, William F.; van der Wiel, Wilfred Gerard; Reinhoudt, David; Whitesides, George M.; Nijhuis, C.A.; Velders, Aldrik

    2010-01-01

    In complete control: The magnitude of current rectification in well-defined supramolecular tunneling junctions can be controlled by changing the terminal functionality (red spheres) of dendrimers (gray spheres) immobilized on a supramolecular platform (see picture). Junctions containing biferrocene

  18. Low Speed Wind Tunnel Facility (LSWTF)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: This facility consists of a large-scale, low-speed open-loop induction wind tunnel which has been modified to house a linear turbine cascade. A 125-hp...

  19. Unknotting tunnels in hyperbolic 3-manifolds

    CERN Document Server

    Adams, Colin

    2012-01-01

    An unknotting tunnel in a 3-manifold with boundary is a properly embedded arc, the complement of an open neighborhood of which is a handlebody. A geodesic with endpoints on the cusp boundary of a hyperbolic 3-manifold and perpendicular to the cusp boundary is called a vertical geodesic. Given a vertical geodesic in a hyperbolic 3-manifold M, we find sufficient conditions for it to be an unknotting tunnel. In particular, if the vertical geodesic corresponds to a 4-bracelet, 5-bracelet or 6-bracelet in the universal cover and has short enough length, it must be an unknotting tunnel. Furthermore, we consider a vertical geodesic that satisfies the elder sibling property, which means that in the universal cover, every horoball except the one centered at infinity is connected to a larger horoball by a lift of the vertical geodesic. Such a vertical geodesic with length less than ln(2) is then shown to be an unknotting tunnel.

  20. Proton tunnelling in intermolecular hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Horsewill, A.J. [Nottingham Univ. (United Kingdom); Johnson, M.R. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France); Trommsdorff, H.P. [Grenoble-1 Univ., 38 (France)

    1997-04-01

    The wavefunctions of particles extend beyond the classically accessible regions of potential energy-surfaces (PES). A manifestation of this partial delocalization is the quantum-mechanical tunneling effect which enables a particle to escape from a metastable potential-well. Tunnelling is most important for the lightest atoms, so that the determination of its contribution to proton transfer, one of the most fundamental chemical reactions, is an important issue. QENS and NMR techniques have been employed to study the motion of protons in the hydrogen bond of benzoic-acid crystals, a system which has emerged as a particularly suitable model since proton transfer occurs in a near symmetric double-well potential. The influence of quantum tunnelling was revealed and investigated in these experiments. This work provides an experimental benchmark for theoretical descriptions of translational proton-tunnelling. (author). 7 refs.

  1. A century of wind tunnels since Eiffel

    Science.gov (United States)

    Chanetz, Bruno

    2017-08-01

    Fly higher, faster, preserve the life of test pilots and passengers, many challenges faced by man since the dawn of the twentieth century, with aviation pioneers. Contemporary of the first aerial exploits, wind tunnels, artificially recreating conditions encountered during the flight, have powerfully contributed to the progress of aeronautics. But the use of wind tunnels is not limited to aviation. The research for better performance, coupled with concern for energy saving, encourages manufacturers of ground vehicles to perform aerodynamic tests. Buildings and bridge structures are also concerned. This article deals principally with the wind tunnels built at ONERA during the last century. Somme wind tunnels outside ONERA, even outside France, are also evocated when their characteristics do not exist at ONERA.

  2. Modeling direct interband tunneling. I. Bulk semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Andrew, E-mail: pandrew@ucla.edu [Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, California 90095 (United States); Chui, Chi On [Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095 (United States)

    2014-08-07

    Interband tunneling is frequently studied using the semiclassical Kane model, despite uncertainty about its validity. Revisiting the physical basis of this formula, we find that it neglects coupling to other bands and underestimates transverse tunneling. As a result, significant errors can arise at low and high fields for small and large gap materials, respectively. We derive a simple multiband tunneling model to correct these defects analytically without arbitrary parameters. Through extensive comparison with band structure and quantum transport calculations for bulk InGaAs, InAs, and InSb, we probe the accuracy of the Kane and multiband formulas and establish the superiority of the latter. We also show that the nonlocal average electric field should be used when applying either of these models to nonuniform potentials. Our findings are important for efficient analysis and simulation of bulk semiconductor devices involving tunneling.

  3. Computer graphic of LHC in the tunnel

    CERN Multimedia

    1996-01-01

    A computer-generated image of the LHC particle accelerator at CERN in the tunnel originally built for the LEP accelerator that was closed in 2000. The cross-section of an LHC superconducting dipole magnet is also seen.

  4. La maquette digitale du tunnel du LEP

    CERN Document Server

    Brouns, G

    2000-01-01

    Pour l'installation du LHC et son équipement périphérique (ligne cryogénique, câbles, tuyauterie, etc.) dans le tunnel du LEP, une maquette digitale CAO doit être faite. Après un rappel de la définition théorique du tunnel du LEP, cette LHC project Note décrit comment sont utilisées et intégrées d'anciennes et de nouvelles mesures du tunnel pour arriver à un ensemble de données qui permettent de construire la maquette digitale (CAO) du tunnel du LHC. Ensuite, les résultats sont comparés à leur valeur théorique d'une part, et aux anciennes valeurs disponibles d'autre part.

  5. Many-electron tunneling in atoms

    CERN Document Server

    Zon, B A

    1999-01-01

    A theoretical derivation is given for the formula describing N-electron ionization of atom by a dc field and laser radiation in tunneling regime. Numerical examples are presented for noble gases atoms.

  6. Teelt van vruchtgewassen in lage tunnels

    NARCIS (Netherlands)

    Wijk, van C.A.P.; Geven, C.G.M.

    1994-01-01

    Een aantal warmteminnende vruchtgewassen zijn beproefd in lage tunnels en vergeleken met onbedekte teelt en met kasteelt. Het betrof aubergine, paprika, peper en diverse typen meloen. Daar is courgette als vergelijkend gewas aan toegevoegd

  7. Decoherence and tunneling of an interacting gas

    Science.gov (United States)

    Anglin, James; Rico-Perez, Luis; Wohlfarth, Daniel

    2015-05-01

    In quasi-steady escape of a confined interacting gas by quantum tunneling, collisional decoherence can reduce the escape rate through a many-body version of the Caldeira-Leggett effect. This explains why classical fluids fail to tunnel, even though they are composed of particles small enough to be quantum mechanical. We compute this effect in the Maxwell-Boltzmann regime by deriving a quantum generalization of the Boltzmann equation. We show that decoherence effectively makes tunneling of an interacting gas into an irreversible process: a uniquely quantum mechanical form of throttling. The rate of entropy production in tunneling is related in the semi-classical limit to the imaginary part of the single-particle action.

  8. A small cable tunnel inspection robot design

    Science.gov (United States)

    Zhou, Xiaolong; Guo, Xiaoxue; Huang, Jiangcheng; Xiao, Jie

    2017-04-01

    Modern city mainly rely on internal electricity cable tunnel, this can reduce the influence of high voltage over-head lines of urban city appearance and function. In order to reduce the dangers of cable tunnel artificial inspection and high labor intensity, we design a small caterpillar chassis in combination with two degrees of freedom robot with two degrees of freedom camera pan and tilt, used in the cable tunnel inspection work. Caterpillar chassis adopts simple return roller, damping structure. Mechanical arm with three parallel shafts, finish the up and down and rotated action. Two degrees of freedom camera pan and tilt are used to monitor cable tunnel with 360 °no dead angle. It looks simple, practical and efficient.

  9. 7 x 10 Foot Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — This wind tunnel is used for basic and applied research in aeromechanics on advanced and unique technology rotorcraft. It supports research on advanced concepts and...

  10. Dynamical quenching of tunneling in molecular magnets

    Energy Technology Data Exchange (ETDEWEB)

    José Santander, María, E-mail: maria.jose.noemi@gmail.com [Recursos Educativos Quántica, Santiago (Chile); Departamento de Física, Universidad de Santiago de Chile and CEDENNA, Avda. Ecuador 3493, Santiago (Chile); Nunez, Alvaro S., E-mail: alnunez@dfi.uchile.cl [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Casilla 487-3, Santiago (Chile); Roldán-Molina, A. [Instituto de Física, Pontificia Universidad Católica de Valparaíso, Avenida Universidad 330, Curauma, Valparaíso (Chile); Troncoso, Roberto E., E-mail: r.troncoso.c@gmail.com [Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Avda. Ecuador 3493, Santiago 9170124 (Chile); Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, Valparaíso (Chile)

    2015-12-15

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation. - Highlights: • Single molecular magnets under rapidly oscillating magnetic fields is studied. • It is shown that this system displays the quenching of tunneling processes. • Our findings provide a control of quantum molecular magnets via terahertz radiation.

  11. LEP sees the end of the tunnel

    CERN Document Server

    2002-01-01

    After 14 months, which have seen the removal of 30,000 tonnes of material from the tunnel, the LEP dismantling operation has now been completed. LHC installation, which will be subject to new safety rules, can go ahead.

  12. Tertiary interactions within the ribosomal exit tunnel.

    Science.gov (United States)

    Kosolapov, Andrey; Deutsch, Carol

    2009-04-01

    Although tertiary folding of whole protein domains is prohibited by the cramped dimensions of the ribosomal tunnel, dynamic tertiary interactions may permit folding of small elementary units within the tunnel. To probe this possibility, we used a beta-hairpin and an alpha-helical hairpin from the cytosolic N terminus of a voltage-gated potassium channel and determined a probability of folding for each at defined locations inside and outside the tunnel. Minimalist tertiary structures can form near the exit port of the tunnel, a region that provides an entropic window for initial exploration of local peptide conformations. Tertiary subdomains of the nascent peptide fold sequentially, but not independently, during translation. These studies offer an approach for diagnosing the molecular basis for folding defects that lead to protein malfunction and provide insight into the role of the ribosome during early potassium channel biogenesis.

  13. Observing Quantum Tunneling in Perturbation Series

    CERN Document Server

    Suzuki, H; Suzuki, Hiroshi; Yasuta, Hirofumi

    1996-01-01

    We apply Borel resummation method to the conventional perturbation series of ground state energy in a metastable potential, $V(x)=x^2/2-gx^4/4$. We observe numerically that the discontinuity of Borel transform reproduces the imaginary part of energy eigenvalue, i.e., total decay width due to the quantum tunneling. The agreement with the exact numerical value is remarkable in the whole tunneling regime $0

  14. Low Power Band to Band Tunnel Transistors

    Science.gov (United States)

    2010-12-15

    the E-field and tunneling at the source- pocket junction you form a parasitic NPN + transistor and the injection mechanism of carriers into the...hypothesis that the 1000 ° C, 5s anneal split lead to a very wide pocket and the accidental formation of a NPN + transistor , while the 1000 ° C, 1s anneal...Low Power Band to Band Tunnel Transistors Anupama Bowonder Electrical Engineering and Computer Sciences University of California at Berkeley

  15. Geology of Pletovarje motorway tunnel (Slovenia

    Directory of Open Access Journals (Sweden)

    Magda Čarman

    2009-06-01

    Full Text Available Styrian motorway crosses the Pletovarje ridge through the tunnel having the same name. It intersects the mosteastern extension of the Southern Karavanke tectonic unit. Considering geological conditions, the tunnel couldbe divided into three sections: the inner Donat / Dona~ka fault zone composed of tectonic lenses of differentlithostratigraphic units (of paleozoic, triassic and tertiary age, massive dolomite (lower triassic and Smrekovecseries of oligocene age. Main faults have east – west direction and are subvertical.

  16. Numerical modeling of tunneling-induced seismicity

    Science.gov (United States)

    Rinaldi, Antonio Pio; Urpi, Luca

    2017-04-01

    Removal of rock mass in mining environment has been associated since long-time with seismic event of magnitude 3 and above, with the potential to cause damage to the infrastructures or even loss of human life. Although with similarities with mining, relatively unknown up to now are seismic events induced by tunneling. However with modern mechanized tunneling techniques, making possible to digging deeper and longer underground infrastructure, the risk is not negligible. As an example, the excavation of the 57km long Gotthard Base Tunnel has been associated more than hundred seismic events, with the largest one having magnitude of ML 2.4, damaging the tunnel infrastructures. For future scenario of deep geological storage of nuclear waste, tunneling will constitute the primary activity during site construction. Hence, it will be crucial to understand the risk associated with the underground construction operation that can reactivate seismogenic features nearby the future location of emplacement tunnels. Here we present numerical simulation aimed at understanding the potential for inducing seismicity during tunnel construction. The stress changes and their evolution during the excavation are evaluated with a finite element solver (FLAC3d). A strain-softening friction model is then used to simulate the occurrence of a sudden slip on a fault zone (if critical conditions for reactivation are reached). We also present a sensitivity analysis of the potential for inducing different seismic events by different tunnel sizes at varying distance from a nearby failure plane, with the final purpose of evaluating safety of a potential nuclear repository site on the short- and long-term.

  17. Aeroelastic instability stoppers for wind tunnel models

    Science.gov (United States)

    Doggett, R. V., Jr.; Ricketts, R. H. (Inventor)

    1981-01-01

    A mechanism for constraining models or sections thereof, was wind tunnel tested, deployed at the onset of aeroelastic instability, to forestall destructive vibrations in the model is described. The mechanism includes a pair of arms pivoted to the tunnel wall and straddling the model. Rollers on the ends of the arms contact the model, and are pulled together against the model by a spring stretched between the arms. An actuator mechanism swings the arms into place and back as desired.

  18. Radio-frequency scanning tunnelling microscopy.

    Science.gov (United States)

    Kemiktarak, U; Ndukum, T; Schwab, K C; Ekinci, K L

    2007-11-01

    The scanning tunnelling microscope (STM) relies on localized electron tunnelling between a sharp probe tip and a conducting sample to attain atomic-scale spatial resolution. In the 25-year period since its invention, the STM has helped uncover a wealth of phenomena in diverse physical systems--ranging from semiconductors to superconductors to atomic and molecular nanosystems. A severe limitation in scanning tunnelling microscopy is the low temporal resolution, originating from the diminished high-frequency response of the tunnel current readout circuitry. Here we overcome this limitation by measuring the reflection from a resonant inductor-capacitor circuit in which the tunnel junction is embedded, and demonstrate electronic bandwidths as high as 10 MHz. This approximately 100-fold bandwidth improvement on the state of the art translates into fast surface topography as well as delicate measurements in mesoscopic electronics and mechanics. Broadband noise measurements across the tunnel junction using this radio-frequency STM have allowed us to perform thermometry at the nanometre scale. Furthermore, we have detected high-frequency mechanical motion with a sensitivity approaching approximately 15 fm Hz(-1/2). This sensitivity is on par with the highest available from nanoscale optical and electrical displacement detection techniques, and the radio-frequency STM is expected to be capable of quantum-limited position measurements.

  19. Radiometric dating of the Siloam Tunnel, Jerusalem.

    Science.gov (United States)

    Frumkin, Amos; Shimron, Aryeh; Rosenbaum, Jeff

    2003-09-11

    The historical credibility of texts from the Bible is often debated when compared with Iron Age archaeological finds (refs. 1, 2 and references therein). Modern scientific methods may, in principle, be used to independently date structures that seem to be mentioned in the biblical text, to evaluate its historical authenticity. In reality, however, this approach is extremely difficult because of poor archaeological preservation, uncertainty in identification, scarcity of datable materials, and restricted scientific access into well-identified worship sites. Because of these problems, no well-identified Biblical structure has been radiometrically dated until now. Here we report radiocarbon and U-Th dating of the Siloam Tunnel, proving its Iron Age II date; we conclude that the Biblical text presents an accurate historic record of the Siloam Tunnel's construction. Being one of the longest ancient water tunnels lacking intermediate shafts, dating the Siloam Tunnel is a key to determining where and when this technological breakthrough took place. Siloam Tunnel dating also refutes a claim that the tunnel was constructed in the second century bc.

  20. Some Caves in tunnels in Dinaric karst of Croatia

    Science.gov (United States)

    Garasic, Mladen; Garasic, Davor

    2016-04-01

    In the last 50 years during the construction of almost all the tunnels in the Croatian Dinaric Karst thousands of caves have been encountered that represented the major problems during the construction works. Geological features (fissures, folding, faults, etc.) are described in this contribution, together with the hydrogeological conditions (rapid changes in groundwater levels). Special engineering geological exploration and survey of each cave, together with the stabilization of the tunnel ceiling, and groundwater protection actions according to basic engineering geological parameters are also presented. In karst tunneling in Croatia over 150 caves longer than 500 m have been investigated. Several caves are over 300 m deep (St. Ilija tunnel in Biokovo Mt), and 10 are longer than 1000 m (St.Rok tunnel, HE Senj and HE Velebit tunnels in Velebit Mt, Ucka tunnel in Ucka Mt, Mala kapela tunnel in Kapela Mt, caverns in HE Plat tunnel etc). Different solutions were chosen to cross the caves depending on the size and purpose of the tunnels (road, rail, pedestrian tunnel, or hydrotechnical tunnels). This is presentations of interesting examples of ceiling stabilization in big cave chambers, construction of bridges inside tunnels, deviations of tunnels, filling caves, grouting, etc. A complex type of karstification has been found in the cavern at the contact between the Palaeozoic clastic impervious formations and the Mesozoic complex of dolomitic limestones in the Vrata Tunnel and at the contact with flysch in the Učka Tunnel. However, karstification advancing in all directions at a similar rate is quite rare. The need to have the roadway and/or tunnel above water from a spring is the biggest possible engineering-geological, hydrogeological and civil engineering challenge. Significant examples are those above the Jadro spring (Mravinci tunnel) in flysch materials or above the Zvir spring in Rijeka (Katarina tunnel), and in fractured Mesozoic carbonates. Today in Croatian

  1. PREFERED SURGICAL TECHNIQUE USED BY ORTHOPEDISTS IN ACUTE ACROMIOCLAVICULAR DISLOCATION

    Science.gov (United States)

    NISHIMI, ALEXANDRE YUKIO; ARBEX, DEMETRIO SIMÃO; MARTINS, DIOGO LUCAS CAMPOS; GUSMÃO, CARLOS VINICIUS BUARQUE DE; BONGIOVANNI, ROBERTO RANGEL; PASCARELLI, LUCIANO

    2016-01-01

    ABSTRACT Objective: To determine whether training on shoulder and elbow surgery influences the orthopedist surgeons' preferred technique to address acute acromioclavicular joint dislocation (ACD). Methods: A survey was conducted with shoulder and elbow specialists and general orthopedists on their preferred technique to address acute ACD. Results: Thirty specialists and forty-five general orthopedists joined the study. Most specialists preferred the endobutton technique, while most general orthopedists preferred the modified Phemister procedure for coracoclavicular ligament repair using anchors. We found no difference between specialists and general orthopedists in the number of tunnels used to repair the coracoclavicular ligament; preferred method for wire insertion through the clavicular tunnels; buried versus unburied Kirschner wire insertion for acromioclavicular temporary fixation; and time for its removal; and regarding the suture thread used for deltotrapezoidal fascia closure. Conclusion: Training on shoulder and elbow surgery influences the surgeons' preferred technique to address acute ACD. Level of Evidence V, Expert Opinion. PMID:28149190

  2. Study on calculation of rock pressure for ultra-shallow tunnel in poor surrounding rock and its tunneling procedure

    Institute of Scientific and Technical Information of China (English)

    Xiaojun Zhou; Jinghe Wang; Bentao Lin

    2014-01-01

    A computational method of rock pressure applied to an ultra-shallow tunnel is presented by key block theory, and its mathematical formula is proposed according to a mechanical tunnel model with super-shallow depth. Theoretical analysis shows that the tunnel is subject to asymmetric rock pressure due to oblique topography. The rock pressure applied to the tunnel crown and sidewall is closely related to the surrounding rock bulk density, tunnel size, depth and angle of oblique ground slope. The rock pressure applied to the tunnel crown is much greater than that to the sidewalls, and the load applied to the left side-wall is also greater than that to the right sidewall. Mean-while, the safety of the lining for an ultra-shallow tunnel in strata with inclined surface is affected by rock pressure and tunnel support parameters. Steel pipe grouting from ground surface is used to consolidate the unfavorable surrounding rock before tunnel excavation, and the reinforcing scope is proposed according to the analysis of the asymmetric load induced by tunnel excavation in weak rock with inclined ground surface. The tunneling procedure of bench cut method with pipe roof protection is still discussed and carried out in this paper according to the special geological condition. The method and tunneling procedure have been successfully utilized to design and drive a real expressway tunnel. The practice in building the super-shallow tunnel has proved the feasibility of the calculation method and tunneling procedure presented in this paper.

  3. Acute Pancreatitis and Pregnancy

    Science.gov (United States)

    ... Acute Pancreatitis and Pregnancy test Acute Pancreatitis and Pregnancy Timothy Gardner, MD Acute pancreatitis is defined as ... pancreatitis in pregnancy. Reasons for Acute Pancreatitis and Pregnancy While acute pancreatitis is responsible for almost 1 ...

  4. Acute Pancreatitis and Pregnancy

    Science.gov (United States)

    ... Pancreatitis Acute Pancreatitis and Pregnancy Acute Pancreatitis and Pregnancy Timothy Gardner, MD Acute pancreatitis is defined as ... pancreatitis in pregnancy. Reasons for Acute Pancreatitis and Pregnancy While acute pancreatitis is responsible for almost 1 ...

  5. Acute Kidney Failure

    Science.gov (United States)

    ... out of balance. Acute kidney failure — also called acute renal failure or acute kidney injury — develops rapidly over ... 2015. Palevsky PM. Definition of acute kidney injury (acute renal failure). http://www.uptodate.com/home. Accessed April ...

  6. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  7. Organic tunnel field effect transistors

    KAUST Repository

    Tietze, Max Lutz

    2017-06-29

    Various examples are provided for organic tunnel field effect transistors (OTFET), and methods thereof. In one example, an OTFET includes a first intrinsic layer (i-layer) of organic semiconductor material disposed over a gate insulating layer; source (or drain) contact stacks disposed on portions of the first i-layer; a second i-layer of organic semiconductor material disposed on the first i-layer surrounding the source (or drain) contact stacks; an n-doped organic semiconductor layer disposed on the second i-layer; and a drain (or source) contact layer disposed on the n-doped organic semiconductor layer. The source (or drain) contact stacks can include a p-doped injection layer, a source (or drain) contact layer, and a contact insulating layer. In another example, a method includes disposing a first i-layer over a gate insulating layer; forming source or drain contact stacks; and disposing a second i-layer, an n-doped organic semiconductor layer, and a drain or source contact.

  8. Tunneling and Transport in Nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Goldman, Allen M. [Univ. of Minnesota, Minneapolis, MN (United States)

    2016-08-16

    The goal of this program was to study new physical phenomena that might be relevant to the performance of conductive devices and circuits of the smallest realizable feature sizes possible using physical rather than biological techniques. Although the initial scientific work supported involved the use of scanning tunneling microscopy and spectroscopy to ascertain the statistics of the energy level distribution of randomly sized and randomly shaped quantum dots, or nano-crystals, the main focus was on the investigation of selected properties, including superconductivity, of conducting and superconducting nanowires prepared using electron-beam-lithography. We discovered a magnetic-field-restoration of superconductivity in out-of-equilibrium nanowires driven resistive by current. This phenomenon was explained by the existence of a state in which dissipation coexisted with nonvanishing superconducting order. We also produced ultra-small superconducting loops to study a predicted anomalous fluxoid quantization, but instead, found a magnetic-field-dependent, high-resistance state, rather than superconductivity. Finally, we developed a simple and controllable nanowire in an induced charged layer near the surface of a masked single-crystal insulator, SrTiO3. The layer was induced using an electric double layer transistor employing an ionic liquid (IL). The transport properties of the induced nanowire resembled those of collective electronic transport through an array of quantum dots.

  9. Le LHC, un tunnel cosmique

    CERN Document Server

    CERN. Geneva

    2009-01-01

    Et si la lumière au bout du tunnel du LHC était cosmique ? En d’autres termes, qu’est-ce que le LHC peut nous apporter dans la connaissance de l’Univers ? Car la montée en énergie des accélérateurs de particules nous permet de mieux appréhender l’univers primordial, chaud et dense. Mais dans quel sens dit-on que le LHC reproduit des conditions proches du Big bang ? Quelles informations nous apporte-t-il sur le contenu de l’Univers ? La matière noire est-elle détectable au LHC ? L’énergie noire ? Pourquoi l’antimatière accumulée au CERN est-elle si rare dans l’Univers ? Et si le CERN a bâti sa réputation sur l’exploration des forces faibles et fortes qui opèrent au sein des atomes et de leurs noyaux, est-ce que le LHC peut nous apporter des informations sur la force gravitationnelle qui gouverne l’évolution cosmique ? Depuis une trentaine d’années, notre compréhension de l’univers dans ses plus grandes dimensions et l’appréhension de son comportement aux plus peti...

  10. Validation of a Compact Isokinetic Total Water Content Probe for Wind Tunnel Characterization at NASA Glenn Icing Research Tunnel and at NRC Ice Crystal Tunnel

    Science.gov (United States)

    Davison, Craig R.; Landreville, Charles; Ratvasky, Thomas P.

    2017-01-01

    A new compact isokinetic probe to measure total water content in a wind tunnel environment has been developed. The probe has been previously tested under altitude conditions. This paper presents a comprehensive validation of the probe under a range of liquid water conditions at sea level in the NASA Glenn Icing Research Tunnel and with ice crystals at sea level at the NRC wind tunnel. The compact isokinetic probe is compared to tunnel calibrations and other probes.

  11. European Tunnelling Review Quality, Environment and Safety Focus

    Institute of Scientific and Technical Information of China (English)

    Bill Weburn

    2004-01-01

    This paper provides an overview of tunnelling projects with some of the themes covered by the Chengdu Tunnelling Conference.(a) Environmental issues and tunnels under high groundwater pressure (Hallandsis Rail Tunnel, Sweden)(b) Fire -fighting and tunnel safety on long highway tunnels (Socatop Tunnel, West Paris)(c) Mechanised tunnelling below the world's largest airport (Heathrow T5) of a quality that avoids disruption to its operation.Each of these overviews show an enhanced performance in regard to project specific events or objectives. Particularly in tunnelling, project owners expect more than just a facility delivered on time for their money: they expect an all round performance respecting deadlines, budget, environmental protection, safety, quality and community harmony. Funding agencies do not always have the same agenda as project owners, acknowledging peripheral selection criteria but often demanding that the lowest bidder be awarded work. All round performance requires all round project selection criteria.

  12. Development of the tunneling junction simulation environment for scanning tunneling microscope evaluation

    Science.gov (United States)

    Gajewski, Krzysztof; Piasecki, Tomasz; Kopiec, Daniel; Gotszalk, Teodor

    2017-03-01

    Proper configuration of scanning tunneling microscope electronics plays an important role in the atomic scale resolution surface imaging. Device evaluation in the tunneling contact between scanning tip and sample may be prone to the surface quality or mechanical disturbances. Thus the use of tunneling junction simulator makes electronics testing more reliable and increases its repeatability. Here, we present the theoretical background enabling the proper selection of electronic components circuitry used as a tunneling junction simulator. We also show how to simulate mechanics related to the piezoelectric scanner, which is applied in real experiments. Practical use of the proposed simulator and its application in metrological characterization of the developed scanning tunneling microscope is also shown.

  13. Determination of the effectiveness of concentrating mine-tunneling operations

    Energy Technology Data Exchange (ETDEWEB)

    Domanov, P.I.

    1979-02-01

    Experimental operations were conducted in 163 tunneling faces equipped with loading machines and mounted drilling machines and in 110 faces equipped with the pneumatic drilling machines 1PNB-2E in order to determine the optimal specific population of tunnellers in a working face. Following computerized processing of the obtained data, mathematical formulas were derived to compute the optimal rate of tunneling drifts with respect to productivity. Relationships were given for the productivity of drift miners and the rate of tunneling drifts, and between the complete cost of tunneling a drift and the velocity of tunneling. 3 figures.

  14. Performance Analysis of VOIP over GRE Tunnel

    Directory of Open Access Journals (Sweden)

    Aria. Asadi Eskandar

    2015-11-01

    Full Text Available Voice over IP (VoIP is commonly known as phone service over the Internet. Any service using public IP network requires certain extent of security. Demand for security in VOIP technology is increasing. VPN is one of the commonly used methods to secure VOIP traffic. In this paper we simulated behavior of a VOIP communication while running over a GRE VPN Tunnel using OPNET Modeler 17.5. During the simulation, such performance parameters as: choice of voice signaling protocol, voice Codec, parameters arising from network QoS (in this study, homogenous vs. heterogeneous network environment and type of VPN tunneling protocol, were examined. We evaluated performance of VOIP communications in homogenous and heterogeneous network environments, configured based on two different signaling protocols, namely H.323 and SIP. Also, G.711 and G.723 were configured and tested as the choice for voice Codecs. GRE was implemented as the tunneling protocol. Result analysis of this study indicated that GRE Tunnel didn't show a significant increase in such call quality of service (QoS performance factors as: end-to-end delay, call setup time, or a decrease in call MOS value. Even though in a non-ideal (heterogeneous network environment, call quality of service (QoS performance factors shoed poor results; however, there was no significant evidence to suggest that GRE Tunnel is the root cause for such poor results.

  15. Tunnel Field-Effect Transistor with Epitaxially Grown Tunnel Junction Fabricated by Source/Drain-First and Tunnel-Junction-Last Processes

    Science.gov (United States)

    Morita, Yukinori; Mori, Takahiro; Migita, Shinji; Mizubayashi, Wataru; Tanabe, Akihito; Fukuda, Koichi; Masahara, Meishoku; Ota, Hiroyuki

    2013-04-01

    We fabricate p- and n-channel Si tunnel field-effect transistors (TFETs) with an epitaxially grown tunnel junction. In a novel source/drain-first and tunnel-junction-last fabrication process, a thin epitaxial undoped Si channel (epichannel) is deposited on a preferentially fabricated p- or n-type source area. The epichannel sandwiched by a gate insulator and a highly doped source well acts as a parallel-plate tunnel capacitor, which effectively multiplies drain current with an enlarged tunnel area. On the basis of its simple structure and easy fabrication, symmetric n- and p-transistor and complementary metal oxide semiconductor inverter operations were successfully demonstrated.

  16. Overview of traffic safety aspects and design in road tunnels

    Directory of Open Access Journals (Sweden)

    Shy Bassan

    2016-07-01

    Drivers in road tunnels generally reduce their speed and increase their lateral position from the right tunnel wall while driving. In shorter tunnels, with reduced driving speed, driver vigilance may be more robust without being hindered by dull driving, which is more common in longer tunnels. Still, in spite of driver alertness, crash rates in tunnels occur due to the tunnel's unusual driving environment. Crash rates are lower in the tunnel inner zone due to driver alertness, especially after passing the transition zone and acclimating to the tunnel environment. The number of crashes, however, is higher along zone 4 (tunnel inner zone, which is the principal zone, as it covers longer driving distance. According to most studies, short tunnels were found to exhibit higher crash rates than long tunnels because the entrance zones incorporate higher crash rates, compared with the midzones; nonetheless, longer unidirectional (freeway and multilane tunnels with higher design speed, entail lower driver alertness and diminished concentration due to relatively monotonous driving in spite of a tunnel's closed environment.

  17. Particle and chemical control using tunnel flow

    Energy Technology Data Exchange (ETDEWEB)

    Chilese, Frank; Delgado, Gildardo R.; Wack, Daniel; Torczynski, John R.

    2017-09-12

    An apparatus for contaminant control, having: a first optical assembly including: a first light homogenizer tunnel with: a first end connected to an extreme ultra-violet light source, a second end in communication with a destination chamber, a first enclosed space, and, a first gas input arranged to introduce a first gas such that the first gas flows in a first direction toward the first end and in a second direction toward the second end. The apparatus alternately having: a second optical assembly including: a second light homogenizer tunnel with: a third end connected to an extreme ultra-violet light source, a fourth end in communication with a destination chamber, a second enclosed space, a diffusion barrier tube including: a fifth end facing the fourth end and a sixth end in communication with a destination chamber, and a second gas input between the second light homogenizer tunnel and the diffusion tube.

  18. Quantum tunneling from paths in complex time

    CERN Document Server

    Bramberger, Sebastian F; Lehners, Jean-Luc

    2016-01-01

    We study quantum mechanical tunneling using complex solutions of the classical field equations. Simple visualization techniques allow us to unify and generalize previous treatments, and straightforwardly show the connection to the standard approach using Euclidean instanton solutions. We demonstrate that the negative modes of solutions along various contours in the complex time plane reveal which paths contribute to tunneling and which do not, and we provide a criterion for identifying the negative modes. Central to our approach is the solution of the background and perturbation equations not only along a single path, but over an extended region of the complex time plane. Our approach allows for a fully continuous and coherent treatment of classical evolution interspersed by quantum tunneling events, and is applicable in situations where singularities are present and also where Euclidean solutions might not exist.

  19. Multidimensional Quantum Tunneling in the Schwinger Effect

    CERN Document Server

    Dumlu, Cesim K

    2015-01-01

    We study the Schwinger effect, in which the external field having a spatio-temporal profile creates electron-positron pairs via multidimensional quantum tunneling. Our treatment is based on Gutzwiller's trace formula for the QED effective action, whose imaginary part is represented by a sum over complex wordlines. The worldlines are multi-periodic, and the periods of motion collectively depend on the strength of spatial and temporal inhomogeneity. We argue that Hamilton's characteristic function that leads to the correct tunneling amplitude must explicitly depend on both periods, and is represented by an average over the internal cycles of motion. We use this averaging method to calculate the pair production rate in an exponentially damped sinusoidal field, where we find that the initial conditions for each family of periodic trajectories lie on a curve in the momentum plane. The ratio of the periods, which may also be referred as the topological index, stays uniform on each curve. Calculation of tunneling am...

  20. Phonon tunneling through a double barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Villegas, Diosdado [Departamento de Física, Universidad Central “Marta Abreu” de Las Villas, CP 54830, Santa Clara, Villa Clara (Cuba); Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico); León-Pérez, Fernando de [Centro Universitario de la Defensa de Zaragoza, Ctra. de Huesca s/n, E-50090 Zaragoza (Spain); Pérez-Álvarez, R. [Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, CP 62209 Cuernavaca (Mexico); Arriaga, J., E-mail: arriaga@ifuap.buap.mx [Instituto de Física, Universidad Autónoma de Puebla, 18 Sur y San Claudio, Edif. 110A, Ciudad Universitaria, 72570 Puebla (Mexico)

    2015-04-15

    The tunneling of optical and acoustic phonons at normal incidence on a double-barrier is studied in this paper. Transmission coefficients and resonance conditions are derived theoretically under the assumption that the long-wavelength approximation is valid. It is shown that the behavior of the transmission coefficients for the symmetric double barrier has a Lorentzian form close to resonant frequencies and that Breit–Wigner's formula have a general validity in one-dimensional phonon tunneling. Authors also study the so-called generalized Hartman effect in the tunneling of long-wavelength phonons and show that this effect is a numerical artifact resulting from taking the opaque limit before exploring the variation with a finite barrier width. This study could be useful for the design of acoustic devices.

  1. Isotope effects of hydrogen and atom tunnelling

    Science.gov (United States)

    Buchachenko, A. L.; Pliss, E. M.

    2016-06-01

    The abnormally high mass-dependent isotope effects in liquid-phase hydrogen (deuterium) atom transfer reactions, which are customarily regarded as quantum effects, are actually the products of two classical effects, namely, kinetic and thermodynamic ones. The former is determined by the rate constants for atom transfer and the latter is caused by nonbonded (or noncovalent) isotope effects in the solvation of protiated and deuterated reacting molecules. This product can mimic the large isotope effects that are usually attributed to tunnelling. In enzymatic reactions, tunnelling is of particular interest; its existence characterizes an enzyme as a rigid molecular machine in which the residence time of reactants on the reaction coordinate exceeds the waiting time for the tunnelling event. The magnitude of isotope effect becomes a characteristic parameter of the internal dynamics of the enzyme catalytic site. The bibliography includes 61 references.

  2. Electronic thermometry in tunable tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  3. Vibration Compensation for Scanning Tunneling Microscope

    Institute of Scientific and Technical Information of China (English)

    LI Meng-chao; FU Xing; WEI Xiao-lei; HU Xiao-tang

    2003-01-01

    The influence of vibration is already one of main obstacles for improving the nano measuring accuracy.The techniques of anti-vibration,vibration isolation and vibration compensation become an important branch in nano measuring field.Starting with the research of sensitivity to vibration of scanning tunneling microscope(STM),the theory,techniques and realization methods of nano vibration sensor based on tunnel effect are initially investigated,followed by developing the experimental devices.The experiments of the vibration detection and vibration compensation are carried out.The experimental results show that vibration sensor based on tunnel effect is characterized by high sensitivity,good frequency characteristic and the same vibratory response characteristic consistent with STM.

  4. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    Science.gov (United States)

    Knutsen, Turid

    2010-01-01

    The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM) is investigated. The alkaline oxygen evolution reaction (OER) was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS) in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

  5. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    Directory of Open Access Journals (Sweden)

    Turid Knutsen

    2010-06-01

    Full Text Available The relationship between the electrocatalytic properties of an electrode and its ability to transfer electrons between the electrode and a metallic tip in a scanning tunneling microscope (STM is investigated. The alkaline oxygen evolution reaction (OER was used as a test reaction with four different metallic glasses, Ni78Si8B14, Ni70Mo20Si5B5, Ni58Co20Si10B12, and Ni25Co50Si15B10, as electrodes. The electrocatalytic properties of the electrodes were determined. The electrode surfaces were then investigated with an STM. A clear relationship between the catalytic activity of an electrode toward the OER and its tunneling characteristics was found. The use of a scanning tunneling spectroscope (STS in electrocatalytic testing may increase the efficiency of the optimization of electrochemical processes.

  6. Coupling quantum tunneling with cavity photons.

    Science.gov (United States)

    Cristofolini, Peter; Christmann, Gabriel; Tsintzos, Simeon I; Deligeorgis, George; Konstantinidis, George; Hatzopoulos, Zacharias; Savvidis, Pavlos G; Baumberg, Jeremy J

    2012-05-11

    Tunneling of electrons through a potential barrier is fundamental to chemical reactions, electronic transport in semiconductors and superconductors, magnetism, and devices such as terahertz oscillators. Whereas tunneling is typically controlled by electric fields, a completely different approach is to bind electrons into bosonic quasiparticles with a photonic component. Quasiparticles made of such light-matter microcavity polaritons have recently been demonstrated to Bose-condense into superfluids, whereas spatially separated Coulomb-bound electrons and holes possess strong dipole interactions. We use tunneling polaritons to connect these two realms, producing bosonic quasiparticles with static dipole moments. Our resulting three-state system yields dark polaritons analogous to those in atomic systems or optical waveguides, thereby offering new possibilities for electromagnetically induced transparency, room-temperature condensation, and adiabatic photon-to-electron transfer.

  7. Positioning systems for underground tunnel environments

    CERN Document Server

    Leite Pereira, Fernando; Theis, Christian

    In the last years the world has witnessed a remarkable change in the computing concept by entering the mobile era. Incredibly powerful smartphones have proliferated at stunning pace and tablet computers are capable of running demanding applications and meet new business requirements. Being wireless, localization has become crucial not only to serve individuals but also help companies in industrial and safety processes. In the context of the Radiation Protection group at CERN, automatic localization, besides allowing to find people, would help improving the radiation surveys performed regularly along the accelerator tunnels. The research presented in this thesis attempts to answer questions relatively to the viability of localization in a harsh conditions tunnel: “Is localization in a very long tunnel possible, meeting its restrictions and without incurring prohibitive costs and infrastructure?”, “Can one achieve meter-level accuracy with GSM deployed over leaky-feeder?”, “Is it possible to prototype...

  8. Electrodiagnostic approach to carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Cherian Ajith

    2006-01-01

    Full Text Available An algorithm for an electrophysiological approach to carpal tunnel syndrome is proposed. This technical note takes into account the standard tests, comparison tests and needle electromyography. If the standard tests are negative, a comparison study can be done to identify cases of minimal or very mild carpal tunnel syndrome (CTS. If comparison studies are negative, CTS can be ruled out and a search for other causes have to be made. If the standard tests are positive, carpal tunnel syndrome can be divided into extreme, severe,moderate and mild cases. Motor comparison study is useful in extreme CTS cases. Needle electromyography is a must in all cases where the standard tests are positive. This streamlined approach allows accurate diagnosis with minimum essential tests.

  9. Quantum tunneling from high dimensional G\\"odel black hole

    CERN Document Server

    Li, Hui-Ling; Zu, Xiao-Tao

    2014-01-01

    Considering quantum gravity effect, we investigate the quantum tunneling from high dimensional Kerr-G\\"odel black hole using generalized Dirac equation. As a result, revised tunneling probability is obtained, and the corrected Hawking temperature is also presented.

  10. Carpal tunnel syndrome after 22 years of Colle's fracture

    Directory of Open Access Journals (Sweden)

    Goyal V

    2003-01-01

    Full Text Available Delayed carpal tunnel syndrome is rare. We describe the electrophysiological findings in a patient with Colle's fracture, who developed carpal tunnel syndrome 22 years after a wrist injury.

  11. Carpal tunnel syndrome: an unusual presentation of brachial hypertrophy.

    OpenAIRE

    Shenoy, K. T.; Saha, P. K.; Ravindran, M

    1980-01-01

    A patient with carpal tunnel syndrome in association with congenital hypertrophy of right upper limb is described. The median nerve also showed hypertrophy. The symptoms were relieved by decompression of the carpal tunnel.

  12. A Top Pilot Tunnel Preconditioning Method for the Prevention of Extremely Intense Rockbursts in Deep Tunnels Excavated by TBMs

    Science.gov (United States)

    Zhang, Chuanqing; Feng, Xiating; Zhou, Hui; Qiu, Shili; Wu, Wenping

    2012-05-01

    The headrace tunnels at the Jinping II Hydropower Station cross the Jinping Mountain with a maximum overburden depth of 2,525 m, where 80% of the strata along the tunnels consist of marble. A number of extremely intense rockbursts occurred during the excavation of the auxiliary tunnels and the drainage tunnel. In particular, a tunnel boring machine (TBM) was destroyed by an extremely intense rockburst in a 7.2-m-diameter drainage tunnel. Two of the four subsequent 12.4-m-diameter headrace tunnels will be excavated with larger size TBMs, where a high risk of extremely intense rockbursts exists. Herein, a top pilot tunnel preconditioning method is proposed to minimize this risk, in which a drilling and blasting method is first recommended for the top pilot tunnel excavation and support, and then the TBM excavation of the main tunnel is conducted. In order to evaluate the mechanical effectiveness of this method, numerical simulation analyses using the failure approaching index, energy release rate, and excess shear stress indices are carried out. Its construction feasibility is discussed as well. Moreover, a microseismic monitoring technique is used in the experimental tunnel section for the real-time monitoring of the microseismic activities of the rock mass in TBM excavation and for assessing the effect of the top pilot tunnel excavation in reducing the risk of rockbursts. This method is applied to two tunnel sections prone to extremely intense rockbursts and leads to a reduction in the risk of rockbursts in TBM excavation.

  13. Acute tonsillitis.

    Science.gov (United States)

    Sidell, Doug; Shapiro, Nina L

    2012-08-01

    Acute tonsillitis is an inflammatory process of the tonsillar tissues and is usually infectious in nature. Acute infections of the palatine tonsils predominantly occur in school-aged children, but patients of any age may be affected. Tonsillitis of viral origin is usually treated with supportive care. Bacterial tonsillitis is most commonly caused by Streptococcus pyogenes. Polymicrobial infections and viral pathogens are also important sources of infection. Penicillins remain the treatment of choice for S. pyogenes tonsillitis, and augmented aminopenicillins have gained utility in concert with the increasing incidence of beta-lactamase producing bacteria. We describe the anatomic features and the immunologic function of the palatine tonsils, including a detailed discussion of history and physical examination findings, treatment recommendations, and possible complications of acute tonsillitis. Establishing an accurate diagnosis and initiating appropriate treatment are key components of managing this common pathologic process.

  14. Gauge-independence of tunneling rates

    CERN Document Server

    Plascencia, Alexis D

    2016-01-01

    It is shown that tunneling rates can be defined in terms of a false-vacuum effective action whose reality and convexity properties differ from those of the corresponding groundstate functional. The tunneling rate is directly related to the false-vacuum effective action evaluated at an extremal "quantum bounce". The Nielsen identities of the false-vacuum functional ensure that the rate remains independent of the choice of gauge-fixing. Our results are nonperturbative and clarify issues related with convexity and radiative corrections.

  15. Vibration measurement and modal analysis for tunneller

    Institute of Scientific and Technical Information of China (English)

    HUANG Min; WU Miao; WEI Ren-zhi

    2001-01-01

    In this paper, the method of vibration measurement and modal analysis for AM~50 Tunneller machine is presented. When the machine was used for cutting man-made coal bed and real coal bed, the vibration of the machine was measured and the results of signal analysis show that the vibration characteristics under the two kinds of working situations are similar. The modal model of the machine is established, and then, the intrinsic vibration characteristics of AM50 tunneller are investigated by means of the method of experimental modal analysis. The vibration response simulation under a set of loading spectra measured is carried out by force response simulation software.

  16. Resonant tunneling in graphene pseudomagnetic quantum dots.

    Science.gov (United States)

    Qi, Zenan; Bahamon, D A; Pereira, Vitor M; Park, Harold S; Campbell, D K; Neto, A H Castro

    2013-06-12

    Realistic relaxed configurations of triaxially strained graphene quantum dots are obtained from unbiased atomistic mechanical simulations. The local electronic structure and quantum transport characteristics of y-junctions based on such dots are studied, revealing that the quasi-uniform pseudomagnetic field induced by strain restricts transport to Landau level- and edge state-assisted resonant tunneling. Valley degeneracy is broken in the presence of an external field, allowing the selective filtering of the valley and chirality of the states assisting in the resonant tunneling. Asymmetric strain conditions can be explored to select the exit channel of the y-junction.

  17. Fire Resistant Panels for the Tunnel Linings

    Directory of Open Access Journals (Sweden)

    Gravit Marina

    2016-01-01

    Full Text Available Presents the results of studies of innovative materials in the field of experimental and theoretical research fire resistance fireproof panels Pyro-Safe Aestuver T. Owing to the assembly simplicity, materials cheapness, high ecological standard, recycling, reuse potential, are benefit. Research work is running to improve the knowledge about fireproof panels Pyro-Safe Aestuver T for tunnel lining, its basic performance, its long term behavior and in particular also its fire proof for example when used for the lining of road tunnels.

  18. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...

  19. Polaronic Tunnelling in Organic Triblock Copolymers

    Institute of Scientific and Technical Information of China (English)

    LIU De-Sheng; ZHANG Da-Cheng; XIE Shi-Jie; MEI Liang-Mo

    2005-01-01

    @@ Polaron tunnelling is studied in xPA/nPPP/xPA (PA for polyacetylene and PPP poly (p-phenylene)) triblock copolymer, which has a well-barrier-well structure. An extended tight-binding Hamiltonian including external electric field is adopted. Without electric field, the injected electrons would not extend over the whole copolymer chain but instead be confined in the segments of PA. This is different from the behaviour of the traditional semiconductors. It is found that the polaron can transfer to the potential barrier-PPP segment when the applied electric field reaches a certain value. The critical polaron tunnelling electric fields depend upon the lengths of PPP segments.

  20. Traceable long range scanning tunneling microscopy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Dimensionally correct and directly traceable measurement is not feasible with conventional scanning tunneling microscopy (STMs) due to severe hysteresis and non-linearity of the commonly applied piezo tube scanners and the very short range.By integrating a custom made probing system based on tunneling current measurement into a commercially available and laser-interferometrically position controlled positioning system, an STM with a principal measuring range of 25 mm×25 mm×5 mm and traceable position measurement has been set-up and tested.

  1. A study for the KAERI research tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.; Hwang, Y. S.; Park, H. S.; Park, S. K.; Park, B. Y.; Bang, K. S.; Kuh, J. H.; Kang, K. H

    1997-12-01

    Major goal of the R and D on the KAERI Research Tunnel in 1997 are 1) concept development of the KAERI research tunnel and its major units 2) computer simulation of facilities 3) study on thermo-hydro mechanical coupling in the vicinity of a waste repository 4) effect of excavated distrubed zone. In addition supplementary site investigation to understand the distribution of stresses in the site was done along with long term monitoring of the water table. (author). 44 refs., 16 tabs., 36 figs

  2. Wind Tunnel Measurements at LM Wind Power

    DEFF Research Database (Denmark)

    Bertagnolio, Franck

    2012-01-01

    This section presents the results obtained during the experimental campaign that was conducted in the wind tunnel at LM Wind Power in Lunderskov from August 16th to 26th, 2010. The goal of this study is to validate the so-called TNO trailing edge noise model through measurements of the boundary...... layer turbulence characteristics and the far-field noise generated by the acoustic scattering of the turbulent boundary layer vorticies as they convect past the trailing edge. This campaign was conducted with a NACA0015 airfoil section that was placed in the wind tunnel section. It is equipped with high...

  3. Prevalence of carpal tunnel syndrome in motorcyclists.

    Science.gov (United States)

    Manes, Harvey R

    2012-05-01

    Carpal tunnel syndrome is prevalent in patients who have a repetitive motion, vibration, or pressure exerted on the wrist joint for an extended period of time. The prevalence of this condition in the general population is approximately 5%. Motorcyclists subject themselves to high levels of vibration from the road and use their wrists to control the motorcycle's brakes, gas intake, and gears via the handlebars. Under these conditions, the author hypothesized that an increased prevalence of carpal tunnel syndrome would be observed in this population.

  4. Treatment of repetitive use carpal tunnel syndrome

    Science.gov (United States)

    Smith, Chadwick F.; Vangsness, C. Thomas; Anderson, Thomas; Good, Wayne

    1995-05-01

    In 1990, a randomized, double-blind study was initiated to evaluate the use of an eight-point conservative treatment program in carpal tunnel syndrome. A total of 160 patients were delineated with symptoms of carpal tunnel syndrome. These patients were then divided into two groups. Both groups were subjected to an ergonomically correct eight-point work modification program. A counterfeit low level laser therapy unit was utilized in Group A, while an actual low level laser therapy unit was utilized in Group B. The difference between Groups A and B was statistically significant in terms of return to work, conduction study improvement, and certain range of motion and strength studies.

  5. Dephasing of quantum tunnelling in molecular nanomagnets

    Institute of Scientific and Technical Information of China (English)

    Zhang Shu-Qun; Chen Zhi-De

    2008-01-01

    Dephasing mechanism of quantum tunnelling in molecular magnets has been studied by means of the spin-coherentstate path integral in a mean field approximation. It is found that the fluctuating uncompensated transverse field from the dipolar-dipolar interaction between molecular magnets contributes a random phase to the quantum interference phase. The resulting transition rate is determined by the average tunnel splitting over the random phase. Such a dephasing process leads to the suppression of quenching due to the quantum phase interference, and to the steps due to odd resonances in hysteresis loop survived, which is in good agreement with experimental observations in molecular nanomagnets Fee and Mn12.

  6. Doka formwork system SL-1 for tunneling. Example: Šentvid tunnel

    OpenAIRE

    Pogačar, Boris

    2006-01-01

    The present work focuses on formwork system SL-1, which was developed by the company Doka - die Schalungstechniker for forming of tunnels and special structures. Formwork in general is presented, along with the methods of tunneling, which are in use today. Doka formwork system SL-1 and its typical parts are described in detail. The use of this formwork system is represented on the example of a cavern in Šentvid tunnel. Discussed are two possible shapes of the cavern: the form of three resembl...

  7. Bias dependent inversion of tunneling magnetoresistance in Fe/GaAs/Fe tunnel junctions

    OpenAIRE

    Moser, J.; Zenger, M.; Gerl, C.; Schuh, D.; Meier, R.; Chen, P.; Bayreuther, G.; Wegscheider, W.; Weiss, D; Lai, C. -H.; Huang, R. -T.; Kosuth, M.; Ebert, H.

    2006-01-01

    We investigated spin dependent transport through Fe/GaAs/Fe tunnel junctions. The tunneling magnetoresistance effect (TMR) was probed for different types of Fe/GaAs interfaces. For interfaces cleaned by hydrogen plasma the TMR effect is increased and observable at room temperature. If an epitaxial Fe/GaAs(001) interface is involved, the tunnel junction exhibits a bias dependent inversion of the TMR effect. This is a first experimental signature for band structure effects at a Fe/GaAs interfac...

  8. Quantum dot resonant tunneling diode single photon detector with aluminum oxide aperture defined tunneling area

    DEFF Research Database (Denmark)

    Li, H.W.; Kardynal, Beata; Ellis, D.J.P.

    2008-01-01

    Quantum dot resonant tunneling diode single photon detector with independently defined absorption and sensing areas is demonstrated. The device, in which the tunneling is constricted to an aperture in an insulating layer in the emitter, shows electrical characteristics typical of high quality...... resonant tunneling diodes. A single photon detection efficiency of 2.1%+/- 0.1% at 685 nm was measured corresponding to an internal quantum efficiency of 14%. The devices are simple to fabricate, robust, and show promise for large absorption area single photon detectors based on quantum dot structures....

  9. Fabrication of magnetic tunnel junctions with epitaxial and textured ferromagnetic layers

    Science.gov (United States)

    Chang, Y. Austin; Yang, Jianhua Joshua

    2008-11-11

    This invention relates to magnetic tunnel junctions and methods for making the magnetic tunnel junctions. The magnetic tunnel junctions include a tunnel barrier oxide layer sandwiched between two ferromagnetic layers both of which are epitaxial or textured with respect to the underlying substrate upon which the magnetic tunnel junctions are grown. The magnetic tunnel junctions provide improved magnetic properties, sharper interfaces and few defects.

  10. Large tunneling magnetoresistance in octahedral Fe3O4 nanoparticles

    OpenAIRE

    Arijit Mitra; Barun Barick; Jeotikanta Mohapatra; Sharma, H.; Meena, S. S.; ASLAM, M.

    2016-01-01

    We have observed large tunneling Magnetoresistance (TMR) in amine functionalized octahedral nanoparticle assemblies. Amine monolayer on the surface of nanoparticles acts as an insulating barrier between the semimetal Fe3O4 nanoparticles and provides multiple tunnel junctions where inter-granular tunneling is plausible. The tunneling magnetoresistance recorded at room temperature is 38% which increases to 69% at 180 K. When the temperature drops below 150 K, coulomb staircase is observed in th...

  11. Dynamic Instability of Tunnel in Blocky Rock Mass

    Institute of Scientific and Technical Information of China (English)

    QI Chengzhi; CHEN Canshou; QIAN Qihu; LUO Jian

    2008-01-01

    The displacements and geometry of the rock blocks and the properties of the rock structure play an important role in the stability of tunnels.Based on the key block model, the dynamic instability analysis of underground tunnel subjected to intensive short-time compressional wave was conducted.The instability of the tunnel caused by the spallation and the inertial effect was distinguished.And the influence of the roof contour curvature of tunnel was also determined.

  12. Numerical analysis of surface subsidence in asymmetric parallel highway tunnels

    Directory of Open Access Journals (Sweden)

    Ratan Das

    2017-02-01

    Full Text Available Tunnelling related hazards are very common in the Himalayan terrain and a number of such instances have been reported. Several twin tunnels are being planned for transportation purposes which will require good understanding for prediction of tunnel deformation and surface settlement during the engineering life of the structure. The deformational behaviour, design of sequential excavation and support of any jointed rock mass are challenging during underground construction. We have raised several commonly assumed issues while performing stability analysis of underground opening at shallow depth. For this purpose, Kainchi-mod Nerchowck twin tunnels (Himachal Pradesh, India are taken for in-depth analysis of the stability of two asymmetric tunnels to address the influence of topography, twin tunnel dimension and geometry. The host rock encountered during excavation is composed mainly of moderately to highly jointed grey sandstone, maroon sandstone and siltstones. In contrast to equidimensional tunnels where the maximum subsidence is observed vertically above the centreline of the tunnel, the result from the present study shows shifting of the maximum subsidence away from the tunnel centreline. The maximum subsidence of 0.99 mm is observed at 4.54 m left to the escape tunnel centreline whereas the maximum subsidence of 3.14 mm is observed at 8.89 m right to the main tunnel centreline. This shifting clearly indicates the influence of undulating topography and in-equidimensional noncircular tunnel.

  13. Consideration of rotational tunneling in rare gas cluster ions

    Science.gov (United States)

    Albertoni, C. R.; Ferguson, A. W. Castleman E. E., Jr.

    1989-04-01

    Tunneling transmission coefficients through rotational barriers are investigated as a function of argon cluster ion size using the WKB approximation. The results indicate that tunneling coefficients corresponding to transmissions of a few percent, extend over time windows of ten orders of magnitude. Hence, a very broad distribution of metastable lifetimes is expected for decay of cluster ions by tunneling through rotational barriers.

  14. Individualized reconstruction plate for treatment of calcaneal fractures via tarsal sinus incision%个体化重建钢板在经跗骨窦切口治疗跟骨骨折中的临床应用

    Institute of Scientific and Technical Information of China (English)

    吴勐; 郭永明; 张朝; 刘重; 石宇; 杨亚龙; 郑文; 魏媛媛

    2015-01-01

    Objective To investigate the clinical efficacy of individualized reconstruction plate in the treatment of calcaneal fractures through the tarsal sinus incision.Methods From May 2010 to September 2012,we treated 46 cases of calcaneal fracture (51 feet) involving talocalcaneal joint.They were 35 males and 11 females,17 to 65 years of age (average,35 years).The injury affected the left foot in 24 cases,the right foot in 17,and both feet in 5.By the Sander's classification,30 feet were type Ⅱ and 21 type 11Ⅲ.The fractures were reduced through the tarsal sinus incision before internal fixation with individualized reconstruction according to the morphology of fracture.When necessary,fixation with hollow screws was added.The B(o)hler and Gissane angles were compared between preoperation and postoperation.The clinical efficacy was evaluated according to the American Orthopaedic Foot and Ankle Society (AOFAS) system.Results The patients were followed up for 8 to 14 months (average,12 months).No such complications as incision infection,skin necrosis,plate loosening or exposure occurred in this group.There were significant differences in the B(o)hler and Gissane angles between preoperation and postoperation [(31.70° ± 5.50° and 122.10° ± 6.79° at 3 days postoperation) and (30.95° ± 3.47° and 122.49° ± 4.83° at 6 months postoperation) versus (6.14° ± 1.58° and 91.63° ± 4.76° at preoperation)] (P < 0.05),but no significant difference in the B(o)hler and Gissane angles between 3 days postoperation and 6 months postoperation (P > 0.05).All the patients obtained bony union at 6 months postoperation.According to the AOFAS scores,38 feet were excellent,9 feet good and 4 feet fair,giving an excellent to good rate of 92.2%.Conclusion In the treatment of intra-articular calcaneal fractures through the tarsal sinus incision,application of individualized reconstruction plate can lead to fine fracture reduction,rigid internal fixation,early exercise

  15. Construction Technique of Long-Span Shallow-Buried Tunnel Considering the Optimal Sequence of Pilot-Tunnel Excavation

    OpenAIRE

    Bao Jin; Yang Liu; Changxi Yang; Zhicheng Tan; Jianyang Zhang

    2015-01-01

    Construction technique considering the optimal sequence of pilot-tunnel excavation was investigated in order to ensure the safety of construction process of long-span shallow-buried tunnel. Firstly, optimal comparisons of the effect of different sequence of pilot-tunnel excavation on the ground settlement were implemented by the numerical analysis. Secondly, an optimal construction method was determined and applied to the construction of a practical tunnel. Some key issues and procedure of th...

  16. Alendronate reduced peri-tunnel bone loss and enhanced tendon graft to bone tunnel healing in anterior cruciate ligament reconstruction

    Directory of Open Access Journals (Sweden)

    PPY Lui

    2013-01-01

    Full Text Available Peri-tunnel bone loss after anterior cruciate ligament (ACL reconstruction is commonly observed, both clinically and experimentally. We aimed to study the effect and mechanisms of different doses of alendronate in the reduction of peri-tunnel bone loss and promotion of graft-bone tunnel healing in ACL reconstruction. Eighty-four ACL-reconstructed rats were divided into 4 groups. Alendronate at different dosages, or saline, were injected subcutaneously weekly, for 2 or 6 weeks post-reconstruction, for vivaCT (computed tomography imaging, biomechanical tests, histology and immunohistochemistry. Alendronate significantly increased bone mass and density of tissue inside bone tunnels except at the epiphyseal region of tibial tunnel. The femoral tunnel diameter decreased significantly in the mid-dose and high-dose alendronate groups compared to that in the saline group at week 6. Alendronate significantly increased the peri-tunnel bone mass and density along all tunnel regions at week 6. Better graft-bone tunnel integration and intra-tunnel graft integrity were observed in the alendronate groups. The ultimate load was significantly higher in the mid-dose and high-dose alendronate groups at week 2, but not at week 6. There was a reduction in matrix metalloprotein (MMP1, MMP13 and CD68-positive cells at the peri-tunnel region and graft-bone interface in the alendronate-treated group compared to the saline group. Alendronate reduced peri-tunnel bone resorption, increased mineralised tissue inside bone tunnel as well as histologically and biomechanically promoted graft-bone tunnel healing, probably by reducing the expression of MMP1, MMP13 and CD68-positive cells. Alendronate might be used for reducing peri-tunnel bone loss and promoting graft-bone tunnel healing at early stage post-ACL reconstruction.

  17. High non-anatomic tunnel position rates in ACL reconstruction failure using both transtibial and anteromedial tunnel drilling techniques.

    Science.gov (United States)

    Jaecker, Vera; Zapf, Tabea; Naendrup, Jan-Hendrik; Pfeiffer, Thomas; Kanakamedala, Ajay C; Wafaisade, Arasch; Shafizadeh, Sven

    2017-07-18

    Although it is well known from cadaveric and biomechanical studies that transtibial femoral tunnel (TT) positioning techniques are associated with non-anatomic tunnel positions, controversial data exist as so far no clinical differences could have been found, comparing transtibial with anteromedial techniques (AM). The purpose of the study was to analyze if graft failure following TT ACL reconstruction was more commonly associated with non-anatomic tunnel position in comparison with the AM technique. We hypothesized that, compared to AM techniques, non-anatomic tunnel positions correlate with TT tunnel positioning techniques. A total of 147 cases of ACL revision surgery were analyzed retrospectively. Primary ACL reconstructions were analyzed regarding the femoral tunnel drilling technique. Femoral and tibial tunnel positions were determined on CT scans using validated radiographic measurement methods. Correlation analysis was performed to determine differences between TT and AM techniques. A total of 101 cases were included, of whom 64 (63.4%) underwent the TT technique and 37 (36.6%) the AM technique for primary ACL reconstruction. Non-anatomic femoral tunnel positions were found in 77.2% and non-anatomical tibial tunnel positions in 40.1%. No correlations were found comparing tunnel positions in TT and AM techniques, revealing non-anatomic femoral tunnel positions in 79.7 and 73% and non-anatomic tibial tunnel positions in 43.7 and 35.1%, respectively (p > 0.05). Considerable rates of non-anatomic femoral and tibial tunnel positions were found in ACL revisions with both transtibial and anteromedial femoral drilling techniques. Despite the potential of placing tunnels more anatomically using an additional AM portal, this technique does not ensure anatomic tunnel positioning. Consequently, the data highlight the importance of anatomic tunnel positioning in primary ACL reconstruction, regardless of the applied drilling technique.

  18. Colloquium on mine shaft, roadway and tunnel. Proceedings; Kolloquium Schacht, Strecke und Tunnel 2005. Tagungsband

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    The conference intended to outline the economic mechanisms of the coal sector and to show the importance of mining and tunneling and the competence in problem solving acquired in this area. Efficient and sustainable use of domestic reserves may help to ensure long-term supply and keep prices stable. Most of the required infrastructure will be located underground in this highly populated country. Technologies of tunneling and horizontal drilling are described and illustrated by the example of a new Cologne underground railway project. Mining and tunnelling have much in common, e.g. drilling and shotfiring, overburden removal, rock strength, supports, protection against liquid and gas leakage, ventilation and air conditioning. Projects like the new Austrian high-speed railway track or the 'Loetschbergbasistunnel' project in Switzerland are examples of tunneling project which are clearly comparable with the construction of a new coal mine.

  19. Tunneling methods used at the railway tunnels construction in Slovak republic

    Directory of Open Access Journals (Sweden)

    Jozef Čížik

    2007-10-01

    Full Text Available Rail transport is an energy-efficient and capital-intensive means of mechanized land transport. Methods of tunneling vary with the nature of the material to be cut through. When soft earth is encountered, the excavation is timbered for support as the work advances; the timbers are sometimes left as a permanent lining for the tunnel. Another method is to cut two parallel excavations in which the side walls are constructed first. Arches connecting them are then built as the material between them is extracted. Portions of the unexcavated center, left temporarily for support, may be removed later. A tunnel cut through rock frequently requires no lining. Often, to speed construction, work is started at both ends. This poses no problem with the cut-and-cover method, but when the tunnel is bored from within, it must be assured that the tubes will actually meet in the center. Modern methods accomplish this with high precision.

  20. Asymmetric voltage behavior of the tunnel magnetoresistance in double barrier magnetic tunnel junctions

    KAUST Repository

    Useinov, Arthur

    2012-06-01

    In this paper, we study the value of the tunnel magnetoresistance (TMR) as a function of the applied voltage in double barrier magnetic tunnel junctions (DMTJs) with the left and right ferromagnetic (FM) layers being pinned and numerically estimate the possible difference of the TMR curves for negative and positive voltages in the homojunctions (equal barriers and electrodes). DMTJs are modeled as two single barrier junctions connected in series with consecutive tunneling (CST). We investigated the asymmetric voltage behavior of the TMR for the CST in the range of a general theoretical model. Significant asymmetries of the experimental curves, which arise due to different annealing regimes, are mostly explained by different heights of the tunnel barriers and asymmetries of spin polarizations in magnetic layers. © (2012) Trans Tech Publications.

  1. Anomalous Tunnel Magnetoresistance and Spin Transfer Torque in Magnetic Tunnel Junctions with Embedded Nanoparticles

    Science.gov (United States)

    Useinov, Arthur; Ye, Lin-Xiu; Useinov, Niazbeck; Wu, Te-Ho; Lai, Chih-Huang

    2015-12-01

    The tunnel magnetoresistance (TMR) in the magnetic tunnel junction (MTJ) with embedded nanoparticles (NPs) was calculated in range of the quantum-ballistic model. The simulation was performed for electron tunneling through the insulating layer with embedded magnetic and non-magnetic NPs within the approach of the double barrier subsystem connected in parallel to the single barrier one. This model can be applied for both MTJs with in-plane magnetization and perpendicular one. We also calculated the in-plane component of the spin transfer torque (STT) versus the applied voltage in MTJs with magnetic NPs and determined that its value can be much larger than in single barrier system (SBS) for the same tunneling thickness. The reported simulation reproduces experimental data of the TMR suppression and peak-like TMR anomalies at low voltages available in leterature.

  2. Resonant tunnel magnetoresistance in double-barrier planar magnetic tunnel junctions

    KAUST Repository

    Useinov, A. N.

    2011-08-24

    We present a theoretical approach to calculate the spin-dependent current and tunnel magnetoresistance (TMR) in a double-barrier magnetic tunnel junction (DMTJ), in which the magnetization of the middle ferromagnetic metal layer can be aligned parallel or antiparallel in relation to the fixed magnetizations of the left and right ferromagnetic electrodes. The electron transport through the DMTJ is considered as a three-dimensional problem, taking into account all transmitting electron trajectories as well as the spin-dependent momentum conservation law. The dependence of the transmission coefficient and spin-polarized currents on the applied voltage is derived as an exact solution to the quantum-mechanical problem for the spin-polarized transport. In the range of the developed physical model, the resonant tunneling, nonresonant tunneling, and enhanced spin filtering can be explained; the simulation results are in good agreement with experimental data.

  3. The overshoot problem in inflation after tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Koushik; Vaudrevange, Pascal M.; Westphal, Alexander

    2011-09-15

    We show the absence of the usual parametrically large overshoot problem of small-field inflation if initiated by a Coleman-De Luccia (CDL) tunneling transition from an earlier vacuum in the limit of small inflationary scale compared to the tunneling scale. For low-power monomial exit potentials V({phi}){proportional_to} {phi}{sup n}; n<4, we derive an expression for the amount of overshoot. This is bounded from above by the width of the steep barrier traversed after emerging from tunneling and before reaching a slow-roll region of the potential. For n{>=}4 we show that overshooting is entirely absent. We extend this result through binomials to a general potential written as a series expansion, and to the case of arbitrary finite initial speed of the inflaton. This places the phase space of initial conditions for small-field and large-field inflation on the same footing in a landscape of string theory vacua populated via CDL tunneling. (orig.)

  4. Cooling of suspended nanostructures with tunnel junctions

    OpenAIRE

    Koppinen, P. J.; Maasilta, I. J.

    2009-01-01

    We have investigated electronic cooling of suspended nanowires with SINIS tunnel junction coolers. The suspended samples consist of a free standing nanowire suspended by four narrow ($\\sim$ 200 nm) bridges. We have compared two different cooler designs for cooling the suspended nanowire. We demonstrate that cooling of the nanowire is possible with a proper SINIS cooler design.

  5. Dissipative tunneling of deuterons in Palladium Deuterides

    Science.gov (United States)

    Sinha, K. P.; Hagelstein, Peter

    2001-03-01

    Decisive experimental evidence exists(B.N.Ganguly,Phys.Rev. B14), 3848(1976). for optical phonons being involved in charged particle-phonon interaction in PdD. We consider the tunneling of charged defects (D^+ or D^-) in a two-state system(K.P.Sinha,Mod.Phys.Lett. B1), 805 (1998)^, (P.L.Hagelstein,To be published.)^,(U.Weiss, \\underline Quantum) \\underline Dissipative \\underline Systems (World Scientific, Singapore, 1999).. The two minima of the potential energy are taken to be asymetrical to reflect the real situation occurring in the solid matrix with defects. A pseudospin formalism is used in which the charged particle interacts with conduction electrons as well as optical phonons. The renormalization effects of the tunneling matrix elements due to interaction with electrons and optical phonons are taken into account. The tunneling rate is derived for both coherent and incoherent situations at finite temperatures. The expressions contain factors which show the emission(absorption) of phonons depending on the direction of the tunneling process. Thus the moving deuteron flux stimulates the generation of optical phonons.

  6. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  7. 3D numerical design of tunnel hood

    CERN Document Server

    Uystepruyst, David; Monnoyer, François

    2015-01-01

    This paper relates to the parametric study of tunnel hoods in order to reduce the shape, i.e the temporal gradient, of the pressure wave generated by the entry of a High speed train in tunnel. This is achieved by using an in-house three-dimensional numerical solver which solves the Eulerian equations on a Cartesian and unstructured mesh. The efficiency of the numerical methodology is demonstrated through comparisons with both experimental data and empirical formula. For the tunnel hood design, three parameters, that can influence the wave shape, are considered: the shape, the section and the length of the hood. The numerical results show, (i) that a constant section hood is the most efficient shape when compared to progressive (elliptic or conical) section hoods, (ii) an optimal ratio between hood's section and tunnel section where the temporal gradient of the pressure wave can be reduced by half, (iii) a significant efficiency of the hood's length in the range of 2 to 8 times the length of the train nose. Fi...

  8. Tunnel Diode Discriminator with Fixed Dead Time

    DEFF Research Database (Denmark)

    Diamond, J. M.

    1965-01-01

    A solid state discriminator for the range 0.4 to 10 V is described. Tunnel diodes are used for the discriminator element and in a special fixed dead time circuit. An analysis of temperature stability is presented. The regulated power supplies are described, including a special negative resistance...

  9. Bilateral carpal tunnel syndrome in Graves' disease.

    Science.gov (United States)

    Manganelli, P; Pavesi, G; Salaffi, F

    1987-01-01

    Carpal tunnel syndrome (CTS) may be associated with endocrinopathies, such as hypothyroidism and acromegaly. A direct relationship between CTS and hyperthyroidism has recently been suggested. We now report a case in which bilateral CTS developed after treatment of Graves' disease, thus, questioning the possibility of a relationship between these two disease processes.

  10. SCANNING TUNNELING MICROSCOPY STUDIES ON OPTICAL DISC

    Institute of Scientific and Technical Information of China (English)

    徐磊; 顾冬红; 等

    1994-01-01

    Scanning tunneling microscope(STM) is used to investigate the optical dise.The areas with and without data stampers are all observedcarefully.Three-dimensional images of the disc surface clearly demonstrate the period.depth of the grooves and the shape of data stampers.Some phenomena of STM imaging are also discussed.

  11. Single electron tunneling based arithmetic computation

    NARCIS (Netherlands)

    Lageweg, C.R.

    2004-01-01

    In this dissertation we investigate the implementation of computer arithmetic operations with Single Electron Tunneling (SET) technology based circuits. In our research we focus on the effective utilization of the SET technologys specific characteristic, i.e., the ability to control the transport of

  12. Towards high-speed scanning tunneling microscopy

    NARCIS (Netherlands)

    Tabak, Femke Chantal

    2013-01-01

    In this thesis, two routes towards high-speed scanning tunneling microscopy (STM) are described. The first possibility for high-speed scanning that is discussed is the use of MEMS (Micro-Electro Mechanical Systems) devices as high-speed add-ons in STM microscopes. The functionality of these devices

  13. Enhanced Tunnelling Models for Child Universe Formation

    CERN Document Server

    Ansoldi, S; Shilon, I

    2015-01-01

    Starting from a recently proposed model that allows for an enhanced rate of child universe production under generic conditions, we elaborate on refinements that may allow for non-singular initial configurations. A possibility to treat both, the initial state and the tunnelling beyond the semiclassical level will also be introduced.

  14. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  15. Radiologic placement of tunneled central venous catheter

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Seong Tae; Yang, Po Song; Yang, Dong Hunn; Kim, Ki Tae; Kim, Choon Yul; Shinn, Kyung Sub [The Catholic Univ. College of Medicine, Seoul (Korea, Republic of); Yun, Eun Joo [Korea Veterans Hospital, Seoul (Korea, Republic of)

    1996-01-01

    To evaluate the efficacy and safety of fluoroscopy-guided, radiologic placement of a tunneled central venous catheter into the superior vena cava (SVC). Thirty five patients underwent tunneled central venous catheter placement to facilitate long-term chemotherapy. They included 33 leukemic patients, one colon cancer patient, and one multiple myeloma patient. After confirming central venous patency with a injection of contrast media via the peripheral cephalic or basilic vein in the wrist joint, the subclavian vein was punctured under fluoroscopic guidance. A 7F double lumen TPN catheter was placed into the SVC through a subcutaneous tunnel in the anterior chest wall. Catheter placements were successful in all patients. The mean procedure time was 17.2minutes, mean fluooscopy time was 1.3minutes, mean number of punctures was 1.4, and mean volume of injhected contrast media was 43.5cc. Only two of all leukemic patients developed mild hematomas at the puncture site, but these soon resolved themselves. None of the patients developed pneumothorax or hemothorax. But late complications included local infection in two patients (6%) and thrombotic occlusion of the catheter in one (3%). The occluded catheter was successfully recanalized with Urokinase infusion. Fluoroscopy-guided, radiologic placement of a tunneled central venous catheter is an easy and safe method, and useful for patients requiring long-term venous access.

  16. Fire safety assessment of tunnel structures

    DEFF Research Database (Denmark)

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco

    2011-01-01

    .g. structural and non structural, organizational, human behavior). This is even more truth for the fire safety design of such structures. Fire safety in tunnels is challenging because of the particular environment, bearing in mind also that a fire can occur in different phases of the tunnel’s lifecycle. Plans...... of nonlinear analyses for different fire exposures....

  17. Integrated tunneling sensor for nanoelectromechanical systems

    DEFF Research Database (Denmark)

    Sadewasser, S.; Abadal, G.; Barniol, N.

    2006-01-01

    distances, attractive van der Waals and capillary forces become sizable, possibly resulting in snap-in of the electrodes. The authors present a comprehensive analysis and evaluation of the interplay between the involved forces and identify requirements for the design of tunneling sensors. Based...

  18. Tunneling spectra of graphene on copper unraveled

    DEFF Research Database (Denmark)

    Zhang, Xin; Stradi, Daniele; Liu, Lei

    2016-01-01

    mechanisms, etc. The interpretation of the spectra can be complicated, however. Specifically for graphene grown on copper, there have been conflicting reports of tunneling spectra. A clear understanding of the mechanisms behind the variability is desired. In this work, we have revealed that the root cause...

  19. Planar Tunneling Spectroscopy of Graphene Nanodevices

    Science.gov (United States)

    Wang, Joel I.-Jan; Bretheau, Landry; Pisoni, Riccardo; Watanabe, Kenji; Taniguchi, Takashi; Jarillo-Herrero, Pablo

    2-D Van-der-Waals mesoscopic physics have seen a rapid development in the last 10 years, with new materials each year added to the toolbox. Stacking them like Lego enables the combination of their individual electronic properties. In particular, hexagonal boron nitride, which is an insulator, gives the possibility to perform planar (2-D to 2-D) tunneling spectroscopy within this type of heterostructures. Unlike standard transport measurements, tunneling spectroscopy enables to probe the electronic properties in the energy domain. Moreover, since planar tunneling probes a large area of the system, global quantum features such as quantum Hall effect, superconducting proximity effect or quantum confinement can be investigated. In this talk, we will present implementation of heterostructures consisting of graphene, hexagonal boron nitride, and graphite, fabricated for planar tunneling spectroscopy. In order to reveal the intrinsic properties of materials, the fabrication scheme aims at preserving the pristine nature of the 2-DEGS as well as minimizing the doping introduced by external probes. As a demonstration, measurements of these devices in normal states, high magnetic field environment, and induced superconducting state will be presented.

  20. Carpal Tunnel Syndrome in ARL Libraries.

    Science.gov (United States)

    Thornton, Joyce K.

    1997-01-01

    A survey of 72 member libraries in the Association of Research Libraries revealed the incidence of carpal tunnel syndrome (CTS) and the measures taken to cope with it. Recommends implementing proactive ergonomics programs; soliciting staff input for solutions; providing report guidelines; using external help; stressing preventive measures and…

  1. Employees' Knowledge of Carpal Tunnel Syndrome.

    Science.gov (United States)

    Gandy-Goldston, Terrie M.

    A study examined employees' knowledge of the causes of carpal tunnel syndrome (CTS), its prevention, and their legal rights after being diagnosed with CTS. A 24-item questionnaire was administered to a random sample of 30 Chicago-area employees who had been afflicted with CTS. Of those surveyed, 99% considered their CTS injury related to their…

  2. An Optimization Model of Tunnel Support Parameters

    Directory of Open Access Journals (Sweden)

    Su Lijuan

    2015-05-01

    Full Text Available An optimization model was developed to obtain the ideal values of the primary support parameters of tunnels, which are wide-ranging in high-speed railway design codes when the surrounding rocks are at the III, IV, and V levels. First, several sets of experiments were designed and simulated using the FLAC3D software under an orthogonal experimental design. Six factors, namely, level of surrounding rock, buried depth of tunnel, lateral pressure coefficient, anchor spacing, anchor length, and shotcrete thickness, were considered. Second, a regression equation was generated by conducting a multiple linear regression analysis following the analysis of the simulation results. Finally, the optimization model of support parameters was obtained by solving the regression equation using the least squares method. In practical projects, the optimized values of support parameters could be obtained by integrating known parameters into the proposed model. In this work, the proposed model was verified on the basis of the Liuyang River Tunnel Project. Results show that the optimization model significantly reduces related costs. The proposed model can also be used as a reliable reference for other high-speed railway tunnels.

  3. Prismatic Blade Measuring on a Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Stech J.

    2013-04-01

    Full Text Available The results from measurement on the straight blade cascade are presented in the paper. The cascade is placed at the outlet of wind tunnel in ŠKODA POWER experimental base. The results in the form of velocity and loss fields behind blade cascade as well as the distribution of the loss coefficient in selected cross-section are evaluated.

  4. Theoretical Analysis of Reinforcement Tunnel Lining Corrosion

    Directory of Open Access Journals (Sweden)

    ZhiQiang Zhangand

    2013-05-01

    Full Text Available The main cause of ageing damage in reinforced concrete structures is reinforcement corrosion. Damage can be detected visually as coincident cracks along the reinforcement bar, which are significant of both reduction of the re-bar, cross-section and loss of bond strength for reinforced concrete. The reinforced concrete is one of the most widely used engineering materials as final lining of tunnels. The corrosion is common durability problems that have significant effect on the tunnel performance. This study intends to analysis reinforcement concrete corrosion at the tunnel lining by applying temperature expansion theory on steel through numerical simulation process, with expansive force effect. The thickness of concrete cover and the diameter of steel bar have an impact on the stress for reinforcement concrete during propagation of corrosion process. The corrosion cracks appear at the corner of a tunnel lining then in invert and vault because the maximum stress will be in the corner then in invert and vault. The internal force in the concrete lining changes differently when the corrosion rate change.

  5. Hemodialysis Tunneled Catheter-Related Infections

    Science.gov (United States)

    Miller, Lisa M.; Clark, Edward; Dipchand, Christine; Hiremath, Swapnil; Kappel, Joanne; Kiaii, Mercedeh; Lok, Charmaine; Luscombe, Rick; Moist, Louise; Oliver, Matthew; MacRae, Jennifer

    2016-01-01

    Catheter-related bloodstream infections, exit-site infections, and tunnel infections are common complications related to hemodialysis central venous catheter use. The various definitions of catheter-related infections are reviewed, and various preventive strategies are discussed. Treatment options, for both empiric and definitive infections, including antibiotic locks and systemic antibiotics, are reviewed.

  6. Decompression of magma into repository tunnels

    NARCIS (Netherlands)

    Bokhove, Onno; Woods, A.W.

    2002-01-01

    It is nontrivial to find and design safe repository sites for nuclear waste. It appears common sense to drill tunnels as repository sites in a mountain in remote and relatively dry regions. However, erosion of the waste canisters by naturally abundant chemicals in the mountains water cycle remains a

  7. ENGINEERING GEOLOGY PROPERTIES OF 'KONJSKO' TUNNEL

    Directory of Open Access Journals (Sweden)

    Ivan Grabovac

    2004-12-01

    Full Text Available Investigation works for the design of the Konjsko Tunnel with two pipes, part of the Split-Zagreb Motorway, provided relevant data on rock mass and soil properties for construction of the prognose engineering-geological longitudinal sections. West tunnel portals are situated in tectonically deformed and partly dynamically metamorphosed Eocene flysch marls, while east ones are located in Senonian limestones. There is an overthrust contact between flysch marls and limestones. With the beginning of the excavations, rock mass characteristics were regularly registered after each blasting and actual longitudinal engineering-geological cross-sections were constructed as well as cross-sections of the excavation face. There were some differences between prognosticated and registered sections since it was infeasible to accurately determine the dip of the overthrust plane that was at shallow depth below the tunnel grade line and also due to the occurrence of transversal faults that intersected the overthrust. Data collected before and during the tunnel construction complemented the knowledge on geological structure of the surroundings and physical-mechanical characteristics of strata (the paper is published in Croatian.

  8. Explosion risks and consequences for tunnels

    NARCIS (Netherlands)

    Weerheijm, J.; Berg, A.C. van den

    2014-01-01

    Tunnel accidents with transports of dangerous goods may lead to explosions. Risk assessment for these accidents is complicated because of the low probability and the unknown, but disastrous effects expected. Especially the lack of knowledge on the strength of the explosion and the consequences for t

  9. PRACTICAL DETERMINATION OF TUNNEL ENTRANCE LIGHTING NEEDS

    NARCIS (Netherlands)

    SCHREUDER, DA

    1991-01-01

    The determination of the field factor that relates the visibility conditions in the laboratory to the visibility conditions for a car driver approaching the entrance of a long tunnel is discussed. Experimental results are given from research in the netherlands. Suggestions are given for incorporatio

  10. B-Target Room Tunnel Redesigned

    Energy Technology Data Exchange (ETDEWEB)

    Esfandiari, Reza; /San Jose State U. /SLAC

    2010-08-25

    Several groups at SLAC National Accelerator Laboratory are currently working on a RF Modulator prototype for a future linear collider known as the International Linear Collider (ILC). The ILC runs using about a 1000 Klystrons which create high power carrier waves for the particle acceleration. Klystrons receive their electrical input power from modulators. In order to move beyond the prototype phase, the laboratory might expand its ground base further down a tunnel located at the End Station B (ESB) in order to house four new Klystron Modulator Test Stations. This area is known as the B-Target Room Tunnel, and the task was to redesign the tunnel layout for the upcoming changes. The project first began by collecting substantial amount of information about the prototyped project, the tunnel and the researchers feedback of what they would like to see in the upcoming design. Subsequent to numerous planning and presentations, one particular design was. Calculations for this design were then performed for the most complex aspects of the project. Based on the results of the calculations, specific sample beams, welds, bolts and materials were chosen for the possible future construction.

  11. High-Performance Single Nanowire Tunnel Diodes

    DEFF Research Database (Denmark)

    Wallentin, Jesper; Persson, Johan Mikael; Wagner, Jakob Birkedal

    2010-01-01

    We demonstrate single nanowire tunnel diodes with room temperature peak current densities of up to 329 A/cm(2). Despite the large surface to volume ratio of the type-II InP-GaAs axial heterostructure nanowires, we measure peak to valley current ratios (PVCR) of up to 8.2 at room temperature and 2...

  12. Resonant tunneling in a pulsed phonon field

    DEFF Research Database (Denmark)

    Kral, P.; Jauho, Antti-Pekka

    1999-01-01

    , The nonequilibrium spectral function for the resonance displays the formation and decay of the phonon sidebands on ultrashort time scales. The time-dependent tunneling current through the individual phonon satellites reflects this quasiparticle formation by oscillations, whose time scale is set by the frequency...

  13. Electric field modulation of tunneling anisotropic magnetoresistance in tunnel junctions with antiferromagnetic electrodes

    Science.gov (United States)

    Goto, Minori; Nawaoka, Kohei; Miwa, Shinji; Hatanaka, Shohei; Mizuochi, Norikazu; Suzuki, Yoshishige

    2016-08-01

    We present electric field modulation of tunneling anisotropic magnetoresistance (TAMR) in MnIr|MgO|Ta tunnel junctions. TAMR enables direct observation of the antiferromagnetic spin direction at the MnIr|MgO interface. We found that the shape of magnetoresistance (MR) curve can be modulated by an electric field, which can be explained by electric field modulation of the interfacial magnetic anisotropy at MnIr|MgO.

  14. The Time and Cost Prediction of Tunnel Boring Machine in Tunnelling

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Making use of microsoft visual studio. net platform, the assistant decision-making system of tunnel boring machine in tunnelling has been built to predict the time and cost. Computation methods of the performance parameters have been discussed. New time and cost prediction models have been depicted. The multivariate linear regression has been used to make the parameters more precise, which are the key factor to affect the prediction near to the reality.

  15. Highly doped layer for tunnel junctions in solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Fetzer, Christopher M.

    2017-08-01

    A highly doped layer for interconnecting tunnel junctions in multijunction solar cells is presented. The highly doped layer is a delta doped layer in one or both layers of a tunnel diode junction used to connect two or more p-on-n or n-on-p solar cells in a multijunction solar cell. A delta doped layer is made by interrupting the epitaxial growth of one of the layers of the tunnel diode, depositing a delta dopant at a concentration substantially greater than the concentration used in growing the layer of the tunnel diode, and then continuing to epitaxially grow the remaining tunnel diode.

  16. Mutual seismic interaction between tunnels and the surrounding granular soil

    Directory of Open Access Journals (Sweden)

    Mohamed Ahmed Abdel-Motaal

    2014-12-01

    Study results show that the maximum exerted straining actions in tunnel lining are directly proportional to the relative stiffness between tunnel and surrounding soil (lining thickness and soil shear modulus. Moreover, it is highly affected by the peak ground acceleration and the tunnel location (embedment depth. A comprehensive study is performed to show the effect of tunnel thickness and tunnel diameter on both the induced bending moment and lining deformation. In general, it is concluded that seismic analysis should be considered in regions subjected to peak ground acceleration greater than 0.15g.

  17. Engineering geology and geomechanics in dam and tunnel construction

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, L. (ed.)

    1981-01-01

    Papers presented at this conference included planning of road tunnels, geological and geotechnical exploration for tunnels, determination of rock mass strength of sedimentary rocks, geomechanical assessment and foundation problems of dams, excavation of mine roadways, movement and stress phenomena in rock strata resulting from hard coal mining, effects of rock bolts and thin linings as tunnel supports, system bolting in deep underground rock excavations, highly stressed areas in tunnels and damage in tunnelling. Papers are either in German or in English. Two papers have been previously abstracted.

  18. Pathogenesis and electrodiagnosis of cubital tunnel syndrome

    Institute of Scientific and Technical Information of China (English)

    贾志荣; 石昕; 孙相如

    2004-01-01

    Background Cubital tunnel syndrome is a well-recognized clinical condition and is the second most common peripheral compression neuropathy. This study was designed to investigate the causes of cubital tunnel syndrome by surgical means and to assess the clinical value of the neurophysiological diagnosis of cubital tunnel syndrome. Methods Twenty-one patients (involving a total of 22 limbs from 16 men and 5 women, aged 22 to 63, with a mean age of 49 years) with clinical symptoms and signs indicating a problem with their ulnar nerve underwent motor conduction velocity examinations at different sites along the ulnar nerve and examinations of sensory conduction velocity in the hand, before undergoing anterior transposition of the ulnar nerve.Results Electromyographic abnormalities were seen in 21 of 22 limbs [motor nerve conduction velocity (MCV) range (15.9-47.5) m/s, mean 32.7 m/s] who underwent motor conduction velocity examinations across the elbow segment of the ulnar nerve. Reduced velocity was observed in 13 of 22 limbs [MCV (15.7-59.6) m/s, mean 40.4 m/s] undergoing MCV tests in the forearms. An absent or abnormal sensory nerve action potential following stimulation was detected in the little finger of 14 of 22 limbs. The factors responsible for ulnar compression based on observations made during surgery were as follows: 15 cases involved compression by arcuate ligaments, muscle tendons, or bone hyperplasia; 2 involved fibrous adhesion; 3 involved compression by the venous plexus or a concurrent thick vein; 2 involved compression by cysts. Conclusions Factors inducing cubital tunnel syndrome include both common factors that have been reported and rare factors, involving the venous plexus, thick veins, and cysts. Tests of motor conduction velocity at different sites along the ulnar nerve should be helpful in diagnosis cubital tunnel syndrome, especially MCV tests indicating decreased velocity across the elbow segment of the ulnar nerve.

  19. Outcome of radiologically placed tunneled haemodialysis catheters.

    Science.gov (United States)

    Sayani, Raza; Anwar, Muhammad; Tanveer-ul-Haq; Al-Qamari, Nauman; Bilal, Muhammad Asif

    2013-12-01

    To study the outcome of radiologically placed double lumen tunneled haemodialysis catheters for the management of renal failure. Case series. Interventional Suite of Radiology Department at the Aga Khan University Hospital, Karachi, from April 2010 to June 2011. All consecutive patients who were referred to the department of radiology by the nephrologists for double lumen tunneled haemodialysis catheter (Permacath) placement during the study period were included. Patients with septicemia, those for whom follow-up was not available, those coming for catheter exchange or who died due to a noncatheter related condition were excluded. A radio-opaque, soft silicone double lumen catheter was inserted through a subcutaneous tunnel created over the anterior chest wall. The catheter tip was placed in the right atrium via the internal jugular vein. Ultrasound guidance was used for initial venous puncture. The rest of the procedure was carried out under fluoroscopic guidance. Technical success, catheter related bacteremia rates, adequacy of dialysis, patency, and adverse events were analyzed. Overall 88 tunneled haemodialysis catheters were placed in 87 patients. Patients were followed-up for duration of 1 - 307 days with mean follow-up period of 4 months. Immediate technical success was 100%. The procedural complication rate was 5.6% (5 catheters). Eight patients died during the study period, seven from causes unrelated to the procedure. One patient died due to septicemia secondary to catheter related infection. Of the remaining 69 patients, 50 (72.4%) predominantly had uneventful course during the study period. Twelve patients developed infection (17.3%); two were successfully treated conservatively while in 10 patients catheter had to be removed. Seven catheters (10.1%) failed due to mechanical problems. In 3 patients the internal jugular veins got partially thrombosed. One catheter was accidentally damaged in the ward and had to be removed. Radiological guided tunneled

  20. Thermal creation of a spin current by Seebeck spin tunneling

    Science.gov (United States)

    Jansen, R.; Le Breton, J. C.; Deac, A. M.; Saito, H.; Yuasa, S.

    2013-09-01

    The thermoelectric analog of spin-polarized tunneling, namely Seebeck spin tunneling, is a recently discovered phenomenon that arises from the spin-dependent Seebeck coefficient of a magnetic tunnel contact. In a tunnel junction with one ferromagnetic electrode and one non-magnetic electrode, a temperature difference between the two electrodes creates a spin current across the contact. Here, the basic principle and the observation of Seebeck spin tunneling are described. It is shown how it can be used to create a spin accumulation in silicon driven by a heat flow across a magnetic tunnel contact, without a charge tunnel current. The sign of the spin current depends on the direction of the heat flow, whereas its magnitude is anisotropic, i.e., dependent on the absolute orientation of the magnetization of the ferromagnet. The connection between Seebeck spin tunneling and the tunnel magneto-Seebeck effect, observed in metal magnetic tunnel junctions, is also clarified. Seebeck spin tunneling may be used to convert waste heat into useful thermal spin currents that aid or replace electrical spin current, and thereby improve the energy efficiency of spintronic devices and technologies.

  1. Monitoring of Deformation in Ground Before and After Tunnel Excavation

    Science.gov (United States)

    Eren, Mehmet; Hilmi Erkoç, Muharrem

    2017-04-01

    As population increase in metropolitan city, we need transportation and transmission tunnel. In this context, the engineers and administors attach impotance to building and planning underground-tunnel. Moreover, we must at regular intervals monitoring to deformation in underground-tunnel for quality and safety. Firstly, a deformation monitoring network is designed as perpendicular to the tunnel main axis. Secondly, the prescribed number of deformation measurements must be made. Finally, the deformation analysis is evaluated and its results is interpreted. This study investigates how deformation in monitoring network during and after tunnel excavate change.For this purpose, a deformation monitoring network of 18 object point and 4 reference point was established. Object points networks was designed steeply to the tunnel main axis as 3 cross section. Each cross section consisted of 3 point left, 2 point right and 1 point at the flowing line. Initial conditional measurement was made before tunnel excavation. Then the deformation measurement was made 5 period (1 period measured after tunnel excavate). All data sets were adjusted according to free adjustment method. The results from the investigation considering the tunnel line, a symmetrical subsidence was observed. The following day of tunnel excavation, we were observed %68 per of the total deformation. At the end of the last period measurements, %99 per of the total deformation was detected. Keywords: Tunnel, Deformation, Subsidence, Excavation

  2. Use of 3D Printing for Custom Wind Tunnel Fabrication

    Science.gov (United States)

    Gagorik, Paul; Bates, Zachary; Issakhanian, Emin

    2016-11-01

    Small-scale wind tunnels for the most part are fairly simple to produce with standard building equipment. However, the intricate bell housing and inlet shape of an Eiffel type wind tunnel, as well as the transition from diffuser to fan in a rectangular tunnel can present design and construction obstacles. With the help of 3D printing, these shapes can be custom designed in CAD models and printed in the lab at very low cost. The undergraduate team at Loyola Marymount University has built a custom benchtop tunnel for gas turbine film cooling experiments. 3D printing is combined with conventional construction methods to build the tunnel. 3D printing is also used to build the custom tunnel floor and interchangeable experimental pieces for various experimental shapes. This simple and low-cost tunnel is a custom solution for specific engineering experiments for gas turbine technology research.

  3. Tunneling Time in Ultrafast Science is Real and Probabilistic

    CERN Document Server

    Landsman, Alexandra; Maurer, Jochen; Boge, Robert; Ludwig, André; Heuser, Sebastian; Cirelli, Claudio; Gallmann, Lukas; Keller, Ursula

    2013-01-01

    We compare the main competing theories of tunneling time against experimental measurements using the attoclock in strong laser field ionization of helium atoms. Refined attoclock measurements reveal a real and not instantaneous tunneling delay time over a large intensity regime, using two different experimental apparatus. Only two of the theoretical predictions are compatible within our experimental error: the Larmor time, and the probability distribution of tunneling times constructed using a Feynman Path Integral (FPI) formulation. The latter better matches the observed qualitative change in tunneling time over a wide intensity range, and predicts a broad tunneling time distribution with a long tail. The implication of such a probability distribution of tunneling times, as opposed to a distinct tunneling time, challenges how valence electron dynamics are currently reconstructed in attosecond science. It means that one must account for a significant uncertainty as to when the hole dynamics begin to evolve.

  4. Inelastic scanning tunneling microscopy in conventional and unconventional superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Hlobil, Patrik; Schmalian, Joerg; Wulfhekel, Wulf; Jandke, Jasmin [Karlsruhe Institute of Technologie (Germany)

    2015-07-01

    Electron tunneling spectroscopy has been used extremely successful in order to verify the microscopic phonon pairing mechanism in conventional BCS superconductors using the Eliashberg theory. Nevertheless, earlier theories and experiments focused mainly on elastic tunneling processes. We present, motivated by recent experiments, a theoretical description of inelastic tunneling in STM in which an electrons tunnels from the tip into a BCS superconductor and coherently excites a phonon during the tunneling process. This additional channel enhances the measured conductivity and we show that if the superconductor is in the normal state, within some limitations, the derivative dσ/dV will be proportional to the Eliashberg function α2F. Additionally, the influence of the inelastic contributions on the tunneling spectrum in the superconducting state will be discussed. Finally, we generalize the theory to other bosonic excitations and focus on the question if inelastic tunneling could be used to unveil the electronic pairing mechanism in the iron pnictides.

  5. Videogrammetric Model Deformation Measurement Technique for Wind Tunnel Applications

    Science.gov (United States)

    Barrows, Danny A.

    2006-01-01

    Videogrammetric measurement technique developments at NASA Langley were driven largely by the need to quantify model deformation at the National Transonic Facility (NTF). This paper summarizes recent wind tunnel applications and issues at the NTF and other NASA Langley facilities including the Transonic Dynamics Tunnel, 31-Inch Mach 10 Tunnel, 8-Ft high Temperature Tunnel, and the 20-Ft Vertical Spin Tunnel. In addition, several adaptations of wind tunnel techniques to non-wind tunnel applications are summarized. These applications include wing deformation measurements on vehicles in flight, determining aerodynamic loads based on optical elastic deformation measurements, measurements on ultra-lightweight and inflatable space structures, and the use of an object-to-image plane scaling technique to support NASA s Space Exploration program.

  6. Superpoissonian shot noise in organic magnetic tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Cascales, Juan Pedro; Martinez, Isidoro; Aliev, Farkhad G., E-mail: farkhad.aliev@uam.es [Dpto. Fisica Materia Condensada C3, Instituto Nicolas Cabrera (INC), Condensed Matter Physics Institute (IFIMAC), Universidad Autonoma de Madrid, Madrid 28049 (Spain); Hong, Jhen-Yong; Lin, Minn-Tsong, E-mail: mtlin@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 10617, Taiwan and Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan (China); Szczepański, Tomasz; Dugaev, Vitalii K. [Department of Physics, Rzeszów University of Technology, al. Powstańców Warszawy 6, 35-959 Rzeszów (Poland); Barnaś, Józef [Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland and Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland)

    2014-12-08

    Organic molecules have recently revolutionized ways to create new spintronic devices. Despite intense studies, the statistics of tunneling electrons through organic barriers remains unclear. Here, we investigate conductance and shot noise in magnetic tunnel junctions with 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA) barriers a few nm thick. For junctions in the electron tunneling regime, with magnetoresistance ratios between 10% and 40%, we observe superpoissonian shot noise. The Fano factor exceeds in 1.5–2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. We explain our main findings in terms of a model which includes tunneling through a two level (or multilevel) system, originated from interfacial bonds of the PTCDA molecules. Our results suggest that interfaces play an important role in the control of shot noise when electrons tunnel through organic barriers.

  7. Acute abdomen

    Directory of Open Access Journals (Sweden)

    Wig J

    1978-01-01

    Full Text Available 550 cases of acute abdomen have been analysed in detail includ-ing their clinical presentation and operative findings. Males are more frequently affected than females in a ratio of 3: 1. More than 45% of patients presented after 48 hours of onset of symptoms. Intestinal obstruction was the commonest cause of acute abdomen (47.6%. External hernia was responsible for 26% of cases of intestinal obstruction. Perforated peptic ulcer was the commonest cause of peritonitis in the present series (31.7% while incidence of biliary peritonitis was only 2.4%.. The clinical accuracy rate was 87%. The mortality in operated cases was high (10% while the over-all mortality rate was 7.5%.

  8. Sinusitis (acute)

    Science.gov (United States)

    2008-01-01

    Introduction Acute sinusitis is defined pathologically, by transient inflammation of the mucosal lining of the paranasal sinuses lasting less than 4 weeks. Clinically, it is characterised by nasal congestion, rhinorrhoea, facial pain, hyposmia, sneezing, and, if more severe, additional malaise and fever. It affects 1−5% of the adult population each year in Europe. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments in people with clinically diagnosed acute sinusitis, and with radiologically or bacteriologically confirmed acute sinusitis? We searched: Medline, Embase, The Cochrane Library and other important databases up to August 2007 (BMJ Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 19 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: antibiotics (amoxicillin, co-amoxiclav, doxycycline, cephalosporins, macrolides, different doses [amoxicillin, co-amoxiclav, doxycycline, cephalosporins, macrolides], long-course regimens), antihistamines, cephalosporins or macrolides, decongestants (xylometazoline, phenylephrine, pseudoephedrine), doxycycline, saline nasal washes, steam inhalation, and topical corticosteroids (intra-nasal). PMID:19450327

  9. Acute Pancreatitis Concomitant Acute Coronary Syndrome

    Directory of Open Access Journals (Sweden)

    Okay Abacı

    2013-03-01

    Full Text Available Acute pancreatitis is an inflammatory syndrome with unpredictable progression to systemic inflammation and multi-organ dysfunction. As in our case rarely, acute pancreatitis can be presented with the coexistance of acute coronary syndrome. To prevent a misdiagnosis of acute situation presented with chest or abdominal pain, physicians must be aware for coexisting pathophysiologies and take into account the differential diagnosis of all life-threatening causes such as cardiac ischemia or acute abdominal situations.

  10. Scanning tunneling microscope assembly, reactor, and system

    Science.gov (United States)

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  11. Subclinical carpal tunnel syndrome in acromegaly.

    Science.gov (United States)

    Kameyama, S; Tanaka, R; Hasegawa, A; Tamura, T; Kuroki, M

    1993-08-01

    Median nerve conduction was studied in 16 acromegalic patients with asymptomatic carpal tunnel syndrome (CTS) to examine the incidence of subclinical CTS. Thirteen patients (81%) and 23 hands (72%) demonstrated subclinical CTS, 10 bilaterally and three unilaterally in the dominant hand. The incidence reflects the greater sensitivity of the inching method for detecting focal conduction abnormalities. Two of three patients without subclinical CTS showed normal plasma somatomedin-C concentration despite growth hormone hypersecretion. Following adenomectomy, nerve conduction normalized in only six hands (26%). The postoperative persistence of the conduction delay implies that irreversible narrowing of the carpal tunnel rather than reversible soft tissue edema is the principal cause of CTS associated with acromegaly.

  12. Construction of tunnel Bôrik

    Directory of Open Access Journals (Sweden)

    Jozef Čížik

    2009-09-01

    Full Text Available When tunneling engineers talk on NATM, they often mean different things because some of them define it as a special technique,but others as a sort of philosophy. Recently the scene has been complicated by new terms and even alternative names, when discussingcertain aspects of NATM.The NATM integrates the principles of the behaviour of rock masses under load and monitoring the performance of undergroundconstruction during construction. The NATM is not a set of specific excavation and support techniques. Based on the computationof the optimal cross section, just a thin shotcrete protection is necessary. Additionally, geotechnical instruments are installed to measurethe later deformation of excavation. Therefore a monitoring of the stress distribution within the rock is possible. This monitoring makesthe method very flexible, even at surprising changes of the geomechanical rock consistency during the tunneling work.

  13. Multiorbital tunneling ionization of the CO molecule

    CERN Document Server

    Wu, J; Kunitski, M; Meckel, M; Voss, S; Sann, H; Kim, H; Jahnke, T; Czasch, A; Dörner, R

    2012-01-01

    We coincidently measure the molecular frame photoelectron angular distribution and the ion sum-momentum distribution of single and double ionization of CO molecules by using circularly and elliptically polarized femtosecond laser pulses, respectively. The orientation dependent ionization rates for various kinetic energy releases allow us to individually identify the ionizations of multiple orbitals, ranging from the highest occupied to the next two lower-lying molecular orbitals for various channels observed in our experiments. Not only the emission of a single electron, but also the sequential tunneling dynamics of two electrons from multiple orbitals are traced step by step. Our results confirm that the shape of the ionizing orbitals determine the strong laser field tunneling ionization in the CO molecule, whereas the linear Stark effect plays a minor role.

  14. Fully magnetic manganite spin filter tunnel junctions

    Science.gov (United States)

    Prasad, Bhagwati; Blamire, Mark G.

    2016-09-01

    In this paper we demonstrate spintronic devices which combine magnetic tunnel junctions with a spin-filtering tunnel barrier. These consist of an ultrathin ferromagnetic insulating barrier, Sm0.75Sr0.25MnO3, sandwiched between two ferromagnetic half-metallic manganite electrodes, La0.7Sr0.3MnO3 and La0.7Ca0.3MnO3, in a nanopillar structure. Depending on the relative magnetic configurations of barrier and electrode layers, three resistance states are well defined, which therefore represent a potential three-state memory concept. These results open the way for the development of spintronic devices by exploiting the many degrees of freedom of perovskite manganite heterostructure systems.

  15. Gravitinos Tunneling From Traversable Lorentzian Wormholes

    CERN Document Server

    Sakalli, I

    2015-01-01

    Recent research shows that Hawking radiation (HR) is also possible around the trapping horizon of a wormhole. In this article, we show that the HR of gravitino (spin-$3/2$) particles from the traversable Lorentzian wormholes (TLWH) reveals a negative Hawking temperature (HT). We first introduce the TLWH in the past outer trapping horizon geometry (POTHG). Next, we derive the Rarita-Schwinger equations (RSEs) for that geometry. Then, using both the Hamilton-Jacobi (HJ) ans\\"{a}tz and the WKB approximation in the quantum tunneling method, we obtain the probabilities of the emission/absorption modes. Finally, we derive the tunneling rate of the emitted gravitino particles, and succeed to read the HT of the TLWH.

  16. Seismic Response of Submerged Floating Tunnel Tether

    Institute of Scientific and Technical Information of China (English)

    SU Zhi-bin; SUN Sheng-nan

    2013-01-01

    A mathematical equation for vibration of submerged floating tunnel tether under the effects of earthquake and parametric excitation is presented.Multi-step Galerkin method is used to simplify this equation and the fourth-order Runge-Kuta integration method is used for numerical analysis.Finally,vibration response of submerged floating tunnel tether subjected to earthquake and parametric excitation is analyzed in a few numerical examples.The results show that the vibration response of tether varies with the seismic wave type; the steady maximum mid-span displacement of tether subjected to seismic wave keeps constant when parametric resonance takes place; the transient maximum mid-span displacement of tether is related to the peak value of input seismic wave acceleration.

  17. Structural and tunneling properties of Si nanowires

    KAUST Repository

    Montes Muñoz, Enrique

    2013-12-06

    We investigate the electronic structure and electron transport properties of Si nanowires attached to Au electrodes from first principles using density functional theory and the nonequilibrium Green\\'s function method. We systematically study the dependence of the transport properties on the diameter of the nanowires, on the growth direction, and on the length. At the equilibrium Au-nanowire distance we find strong electronic coupling between the electrodes and nanowires, which results in a low contact resistance. With increasing nanowire length we study the transition from metallic to tunneling conductance for small applied bias. For the tunneling regime we investigate the decay of the conductance with the nanowire length and rationalize the results using the complex band structure of the pristine nanowires. The conductance is found to depend strongly on the growth direction, with nanowires grown along the ⟨110⟩ direction showing the smallest decay with length and the largest conductance and current.

  18. Interpreting Attoclock Measurements of Tunnelling Times

    CERN Document Server

    Torlina, Lisa; Kaushal, Jivesh; Muller, Harm Geert; Ivanov, Igor; Kheifets, Anatoli; Zielinski, Alejandro; Scrinzi, Armin; Ivanov, Misha; Smirnova, Olga

    2014-01-01

    We discuss measurements of time-delays during strong-field ionization of atoms using few-cycle circularly polarized laser pulses -- the attoclock setup. We perform numerical experiments for the benchmark system of the hydrogen atom and analyze them using fully quantum analytical theory with no ad-hoc assumptions or adjustable parameters. Excellent quantitative agreement between theory and ab initio simulations allows us to characterize time-delays measured by the attoclock, demonstrate that these delays are not related to tunnelling delays and are induced entirely by the interaction of the liberated electron with the long-range Coulomb potential of the ionic core. Our analysis gives access to 'ionization times' -- the times when an electron exits the tunnelling barrier created by the combination of the laser field and the core potential, showing that some of the key assumptions used in the semiclassical interpretation of the attoclock experiments do not always agree with the fully quantum analysis.

  19. Tunnel backfill erosion by dilute water

    Energy Technology Data Exchange (ETDEWEB)

    Olin, M. [VTT Technical Research Centre of Finland, Espoo (Finland)

    2014-03-15

    The goal was to estimate smectite release from tunnel backfill due to dilute groundwater pulse during post glacial conditions. The plan was to apply VTT's two different implementations (BESW{sub D} and BESW{sub S}) of well-known model of Neretnieks et al. (2009). It appeared difficult to produce repeatable results using this model in COMSOL 4.2 environment, therefore a semi-analytical approximate approach was applied, which enabled to take into account both different geometry and smectite content in tunnel backfill as compared to buffer case. The results are quite similar to buffer results due to the decreasing effect of smaller smectite content and the increasing effect of larger radius. (orig.)

  20. Tunnelling matrix elements with Gutzwiller wave functions

    Energy Technology Data Exchange (ETDEWEB)

    Di Ciolo, Andrea; Tocchio, Luca F.; Gros, Claudius [Institut fuer Theoretische Physik, Goethe Universitaet Frankfurt, Frankfurt Am Main (Germany)

    2011-07-01

    We use a generalized Gutzwiller approach, in order to study projected particle (hole) excitations for superconducting systems and systems with antiferromagnetic (AFM) order. As in the standard Gutzwiller scheme the effects of the strong electronic correlations are given via the suppression of the site double occupancy; for our computations it is helpful to consider a lattice with a reservoir site unaffected by this suppression of the double occupancy. In this approach we obtain the probabilities for the tunnelling of a particle (hole) into the projected state. Our results are due only to the physical properties of the trial state and not to the choice of a specifical Hamiltonian: in this sense, they are model-independent but not universal, because they rely on the features of the chosen Gutzwiller wave function (projected Fermi Sea, BCS superconductor, AFM..) The accuracy and the reliability of our analytical approximation is tested using the Variational Monte Carlo. Possible comparisons with tunnelling experiments are discussed.

  1. Control of Smoke Flow in a Tunnel

    Directory of Open Access Journals (Sweden)

    K Brahim

    2013-01-01

    Full Text Available This study focuses on fires in road tunnels in order to increase the level of security for users. This paper proposed numerical investigations carried out on a small scale tunnel model to study the fire-induced smoke control by longitudinal and longitudinal-natural ventilation systems. We studied the effect of two ventilation systems on the temperature distribution and stratification of the pollutant to estimate the effectiveness of ventilation systems. The flow is characterized by the temperature fields, temperature profiles and the Froude number. The numerical tool used is FDS (version 4.0. This numerical study requires validation with experiment and numerical results and comparison with the model developed by Kunsch J.P. to evaluate the critical velocity. However, good agreement with experimental results, it confirms the possibility of using this code in the problem.

  2. Small Numbers From Tunneling Between Brane Throats

    Energy Technology Data Exchange (ETDEWEB)

    Kachru, Shamit

    2001-07-25

    Generic classes of string compactifications include ''brane throats'' emanating from the compact dimensions and separated by effective potential barriers raised by the background gravitational fields. The interaction of observers inside different throats occurs via tunneling and is consequently weak. This provides a new mechanism for generating small numbers in Nature. We apply it to the hierarchy problem, where supersymmetry breaking near the unification scale causes TeV sparticle masses inside the standard model throat. We also design naturally long-lived cold dark matter which decays within a Hubble time to the approximate conformal matter of a long throat. This may soften structure formation at galactic scales and raises the possibility that much of the dark matter of the universe is conformal matter. Finally, the tunneling rate shows that the coupling between throats, mediated by bulk modes, is stronger than a naive application of holography suggests.

  3. View of the LHC tunnel with worker.

    CERN Document Server

    Maximilien Brice

    2006-01-01

    The 616th dipole out of 1232, on its way to its final position in the tunnel of the LHC. Technicians and engineers continue to work day and night carefully installing 20 magnets a week. Each of the dipoles weighs 34 tonnes and is 15 m long. Once they have been lowered down the specially constructed shaft on the Meyrin site, they begin a slow progression to their final destinations in the LHC tunnel, taking about 10 hours to arrive at Point 6, the furthest point on the LHC ring. Upon arrival, each of the dipoles is aligned and interconnected to the magnets that are already installed.Bigger files available (39Mpx)

  4. Alternative diagnostic technique for carpal tunnel syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Hayakawa, Katsuhiko; Nakane, Takashi [Aiko Orthopaedic Hospital, Nagoya (Japan); Kobayashi, Shigeru; Shibata, Kunio [Fujita Health Univ., Toyoake, Aichi (Japan). School of Medicine

    2002-10-01

    Compressive and entrapment neuropathies are common clinical syndromes characterized by neurologic deficits due to mechanical or dynamic compression of peripheral nerves. However, the definitive diagnosis based on clinical symptoms alone is difficult in many cases, and the electrophysiological diagnostic method is solely used as a supplementary diagnostic method at present. As a new diagnostic method for entrapment neuropathy, the present study investigated the usefulness of gadolinium-enhanced MRI in carpal tunnel syndrome. On enhanced MRI of idiopathic carpal tunnel syndrome, contrast-enhancement in the median nerve was found in 30 of 34 hands (88.2%). Enhanced MRI allows to visualize intraneural edema in the nerve easily on the naked eye. Therefore, this technique supplied useful information for making definitive diagnosis and is promising as a non-invasive diagnostic method for entrapment neuropathy. (author)

  5. Wind tunnel measurements of windscreen performance

    Science.gov (United States)

    Maniet, Edward R.

    2002-05-01

    Microphone windscreens are routinely used in outdoor acoustic measurements to reduce wind noise pickup. Characterization of windscreen performance outdoors with real wind has several drawbacks notably that the test conditions cannot be controlled. Test methodology has been developed that provides controlled, repeatable measurements of microphone windscreen performance in a laboratory setting. Wind noise measurements are performed using a high-speed/laminar-flow, low-noise wind tunnel that incorporates a large anechoic chamber. The wind tunnel is modified to produce a turbulent flow into which the microphone and windscreen under evaluation are placed. The turbulent velocity spectrum is measured using multi-axis hot-wire anemometers and compared to outdoor data to locate the best position in the turbulent flow to place the test article. Comparative performance measurements of several windscreen designs are presented.

  6. Tunneling of trapped-atom Bose condensates

    Indian Academy of Sciences (India)

    Subodh R Shenoy

    2002-02-01

    We obtain the dynamics in number and phase difference, for Bose condensates that tunnel between two wells of a double-well atomic trap, using the (nonlinear) Gross–Pitaevskii equation. The dynamical equations are of the canonical form for the two conjugate variables, and the Hamiltonian corresponds to that of a momentum-shortened pendulum, supporting a richer set of tunneling oscillation modes than for a superconductor Josephson junction, that has a fixed-length pendulum as a mechanical model. Novel modes include ‘inverted pendulum’ oscillations with an average angle of ; and oscillations about a self-maintained population imbalance that we term ‘macroscopic quantum self-trapping’. Other systems with this phase-number nonlinear dynamics include two-component (interconverting) condensates in a single harmonic trap, and He3B superfluids in two containers connected by micropores.

  7. Fire safety case study of a railway tunnel: Smoke evacuation

    Directory of Open Access Journals (Sweden)

    van Maele Karim

    2007-01-01

    Full Text Available When a fire occurs in a tunnel, it is of great importance to assure the safety of the occupants of the tunnel. This is achieved by creating smoke-free spaces in the tunnel through control of the smoke gases. In this paper, results are presented of a study concerning the fire safety in a real scale railway tunnel test case. Numerical simulations are performed in order to examine the possibility of natural ventilation of smoke in inclined tunnels. Several aspects are taken into account: the length of the simulated tunnel section, the slope of the tunnel and the possible effects of external wind at one portal of the tunnel. The Fire Dynamics Simulator of the National Institute of Standards and Technology, USA, is applied to perform the simulations. The simulations show that for the local behavior of the smoke during the early stages of the fire, the slope of the tunnel is of little importance. Secondly, the results show that external wind and/or pressure conditions have a large effect on the smoke gases inside the tunnel. Finally, some idea for the value of the critical ventilation velocity is given. The study also shows that computational fluid dynamics calculations are a valuable tool for large scale, real life complex fire cases. .

  8. Tunnels: different construction methods and its use for pipelines installation

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Tales; Soares, Ana Cecilia; Assis, Slow de; Bolsonaro, Ralfo; Sanandres, Simon [Petroleo do Brasil S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    In a continental dimensions country like Brazil, the pipeline modal faces the challenge of opening ROW's in the most different kind of soils with the most different geomorphology. To safely fulfill the pipeline construction demand, the ROW opening uses all techniques in earthworks and route definition and, where is necessary, no digging techniques like horizontal directional drilling, micro tunneling and also full size tunnels design for pipelines installation in high topography terrains to avoid geotechnical risks. PETROBRAS has already used the tunnel technique to cross higher terrains with great construction difficult, and mainly to make it pipeline maintenance and operation easier. For the GASBOL Project, in Aparados da Serra region and in GASYRG, in Bolivia, two tunnels were opened with approximately 700 meters and 2,000 meters each one. The GASBOL Project had the particularity of being a gallery with only one excavation face, finishing under the hill and from this point was drilled a vertical shaft was drilled until the top to install the pipeline section, while in GASYRG Project the tunnel had two excavation faces. Currently, two projects are under development with tunnels, one of then is the Caraguatatuba-Taubate gas pipeline (GASTAU), with a 5 km tunnel, with the same concepts of the GASBOL tunnel, with a gallery to be opened with the use of a TBM (Tunneling Boring Machine), and a shaft to the surface, and the gas pipeline Cabiunas-Reduc III (GASDUC III) project is under construction with a 3.7 km tunnel, like the GASYRG tunnel with two faces. This paper presents the main excavation tunneling methods, conventional and mechanized, presenting the most relevant characteristics from both and, in particular, the use of tunnels for pipelines installation. (author)

  9. Tunnel magnetoresistance in magnetic tunnel junctions with ZnS barrier

    Energy Technology Data Exchange (ETDEWEB)

    Guth, M.; Da Costa, V.; Schmerber, G.; Dinia, A.; van den Berg, H. A. M.

    2001-06-01

    A first experimental evidence of a significant tunneling magnetoresistance signal of about 5% at 300 K for a magnetic tunnel junction consisting of hard and soft magnetic layers separated by a 2 nm ZnS semiconducting barrier is reported. The samples have been grown by sputtering on Si(111) substrate at room temperature and have the following structure: Fe{sub 6nm}Cu{sub 30nm}CoFe{sub 1.8nm}Ru{sub 0.8nm}CoFe{sub 3nm}ZnS{sub x}CoFe{sub 1nm}Fe{sub 4nm}Cu{sub 10nm}Ru{sub 3nm}. The hard magnetic bottom electrode consists of the artificial antiferromagnetic structure in which the rigidity is ensured by the antiferromagnetic exchange coupling between two FeCo layers through a Ru spacer layer. Barrier impedance scanning microscope (BISM) measurements reveal a good homogeneity of the barrier thickness. Electric transport measurements over square tunnel elements with lateral sizes between 3 and 100 {mu}m, exhibit a typical tunnel current{endash}voltage variations and tunnel resistance of 2{endash}3 k{Omega}{mu}m2 with small variations which never exceed a factor of 2, which is in good agreement with the BISM results. This good reproducibility of the junctions is very promising for MRAMs and transistors applications. {copyright} 2001 American Institute of Physics.

  10. Observing Quantum Tunneling in Perturbation Series

    CERN Document Server

    Suzuki, H; Suzuki, Hiroshi; Yasuta, Hirofumi

    1997-01-01

    It is well-known that the quantum tunneling makes conventional perturbation series non-Borel summable. We use this fact reversely and attempt to extract the decay width of the false-vacuum from the actual perturbation series of the vacuum energy density (vacuum bubble diagrams). It is confirmed that, at least in quantum mechanical examples, our proposal provides a complimentary approach to the the conventional instanton calculus in the strong coupling region.

  11. The Femarnbelt Tunnel: Regional Development Perspectives

    DEFF Research Database (Denmark)

    Matthiessen, Christian Wichmann; Lundhus, Peter

    2011-01-01

    The Fehmarnbelt Link between Denmark and Germany, for which in September 2008 a bilateral government treaty was signed, is the last of the three links uniting transportation networks in Northern Europe. The three links (the Great Belt and the Øresund Link being the other two) are impressive mega...... it was decided that an immersed tunnel should form the basis for the continuous planning of the project, including the environmental impact studies. Completion of the link is scheduled for 2020...

  12. Seebeck Effect in Magnetic Tunnel Junctions

    OpenAIRE

    Walter, Marvin; Walowski, Jakob; Zbarsky, Vladyslav; Münzenberg, Markus; Schäfers, Markus; Ebke, Daniel; Reiss, Günter; Thomas, Andy; Peretzki, Patrick; Seibt, Michael; Moodera, Jagadeesh S.; Czerner, Michael; Bachmann, Michael; Heiliger, Christian

    2011-01-01

    Creating temperature gradients in magnetic nanostructures has resulted in a new research direction, i.e., the combination of magneto- and thermoelectric effects. Here, we demonstrate the observation of one important effect of this class: the magneto-Seebeck effect. It is observed when a magnetic configuration changes the charge based Seebeck coefficient. In particular, the Seebeck coefficient changes during the transition from a parallel to an antiparallel magnetic configuration in a tunnel j...

  13. Aeronautical Wind Tunnels, Europe and Asia

    Science.gov (United States)

    2006-02-01

    closed-circuit wind tunnel, 8-kW motor. Operates at sub-freezing temperatures. Built of wood and epoxy-fiberglass composite. Internally insulated with...airplane models. Also used to test wind loads on buildings, bridges, radar antennas, and television towers, and aerodynamic performance of windmills ...flow. This facility has a mahogany six- bladed fan powered by a 2000-hp, 750-V DC motor. At full speed this facility can run at 1.5 MVA. Data

  14. Python Engine Installed in Altitude Wind Tunnel

    Science.gov (United States)

    1949-01-01

    An engine mechanic checks instrumentation prior to an investigation of engine operating characteristics and thrust control of a large turboprop engine with counter-rotating propellers under high-altitude flight conditions in the 20-foot-dianieter test section of the Altitude Wind Tunnel at the Lewis Flight Propulsion Laboratory of the National Advisory Committee for Aeronautics, Cleveland, Ohio, now known as the John H. Glenn Research Center at Lewis Field.

  15. Tunneling of electrons through semiconductor superlattices

    Indian Academy of Sciences (India)

    C L Roy

    2002-11-01

    The purpose of the present paper is to report a study of tunneling of electrons through semiconductor superlattices (SSL); specially, we have analysed diverse features of transmission coefficient of SSL. The SSL we have considered is Ga0.7Al0.3As–GaAs which has been drawing considerable attention during the recent past on account of some typical features of its band structure. We have indicated how our results would help fabrication of ultra high speed devices.

  16. Trophic ulcers in the carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Abelardo Q.-C. Araújo

    1993-09-01

    Full Text Available A patient with carpal tunnel syndrome (CTS and trophic ulcers is described. Despite the healing of the ulcers after surgery for CTS, the severe sensory deficit and the electrophysiological tests have not shown any significant improvement. We think these findings argue against the hypothesis of the sensory deficit being responsible for the trophic ulcers. We favor a major role for the sympathetic disturbances as the main cause for those lesions.

  17. Phase control of resonant tunneling in nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Kaminski, Jerzy Z.; Saczuk, Ewa; Velez, Felipe Cajiao [Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Hoza, 69, 00-681, Warszawa (Poland)

    2013-02-15

    Resonant tunneling of electrons through a multiple potential barrier in a semiconductor heterostructure in the presence of both an oscillating in time and constant external electric fields is considered. In order to solve the problem numerically the concept of the scattering matrix is developed and a stable numerical algorithm is presented. Using this algorithm computations for different amplitudes and different spatial configurations of the fields are performed. (copyright 2012 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Brownian refrigeration by hybrid tunnel junctions

    OpenAIRE

    Peltonen, J. T.; Helle, M.; Timofeev, A. V.; Solinas, P.; Hekking, F. W. J.; Pekola, Jukka P.

    2011-01-01

    Voltage fluctuations generated in a hot resistor can cause extraction of heat from a colder normal metal electrode of a hybrid tunnel junction between a normal metal and a superconductor. We extend the analysis presented in Phys. Rev. Lett. 98, 210604 (2007) of this heat rectifying system, bearing resemblance to a Maxwell’s demon. Explicit analytic calculations show that the entropy of the total system is always increasing. We then consider a single-electron transistor configuration with two ...

  19. O(3)-invariant tunneling in general relativity

    Energy Technology Data Exchange (ETDEWEB)

    Berezin, V.A.; Tkachev, I.I.; Kuzmin, V.A.

    1988-06-30

    We derived a general formula for the action for any O(3)-invariant tunneling processes in false vacuum decay in general relativity. The general classification of the bubble euclidean trajectories is elaborated and explicit expressions for bounces for some processes like the vacuum creation of a double bubble in particular in the vicinity of a black hole, the subbarrier creation of the Einstein-Rosen bridge, creation from nothing of two Minkowski worlds connected by a shell, etc., are given.

  20. Interfacial capacitance effects in magnetic tunneling junctions

    CERN Document Server

    Landry, G; Du, J; Xiao, J Q

    2001-01-01

    We have investigated the AC transport properties of magnetic tunnel junctions (MTJ) in order to characterize interfacial properties. One such property is interfacial charge accumulation, which leads to a voltage drop in the electrodes of the MTJ and the measured capacitance differing from the geometrical capacitance. Through measurement of capacitance spectra, we have extracted an interfacial capacitance of 16 mu F/cm sup 2 per interface and a screening length of 0.55 A for FeNi electrodes.

  1. Sulphate reduction in the Aespoe HRL tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Gustafson, G. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Geology; Laaksoharju, M. [ed.; Skaarman, C. [GeoPoint AB, Sollentuna (Sweden); Pedersen, K. [Goeteborg Univ. (Sweden). Dept. of Genetics, Microbiology and Molecular Biology; Rhen, I. [VBB Viak (Sweden); Tullborg, E.L. [Terralogica AB (Sweden); Wallin, B. [Geokema AB (Sweden); Wikberg, P. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    1995-12-01

    Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl{sup -} concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs.

  2. Sensitivity of resonant tunneling diode photodetectors

    Science.gov (United States)

    Pfenning, Andreas; Hartmann, Fabian; Langer, Fabian; Kamp, Martin; Höfling, Sven; Worschech, Lukas

    2016-09-01

    We have studied the sensitivity of AlGaAs/GaAs double barrier resonant tunneling diode photodetectors with an integrated GaInNAs absorption layer for light sensing at the telecommunication wavelength of λ = 1.3 μm for illumination powers from pico- to microwatts. The sensitivity decreases nonlinearly with power. An illumination power increase of seven orders of magnitude leads to a reduction of the photocurrent sensitivity from S I = 5.82 × 103 A W-1 to 3.2 A W-1. We attribute the nonlinear sensitivity-power dependence to an altered local electrostatic potential due to hole-accumulation that on the one hand tunes the tunneling current, but on the other hand affects the lifetime of photogenerated holes. In particular, the lifetime decreases exponentially with increasing hole population. The lifetime reduction results from an enhanced electrical field, a rise of the quasi-Fermi level, and an increased energy splitting within the triangular potential well. The non-constant sensitivity is a direct result of the non-constant lifetime. Based on these findings, we provide an expression that allows us to calculate the sensitivity as a function of illumination power and bias voltage, show a way to model the time-resolved photocurrent, and determine the critical power up to which the resonant tunneling diode photodetector sensitivity can be assumed constant.

  3. Charge Transport in Resonant Tunneling Double - Diodes

    Science.gov (United States)

    Diff, Karim

    With the advent of semiconductor devices with typical lengths of the order of a few nanometers and response times of a few picoseconds, the conventional methods used in device modeling have reached their limits of validity. Modern devices based on heterostructures fabricated by Molecular Beam Epitaxy (MBE) require more fundamental approaches based entirely on quantum mechanics. These generally necessitate numerical solutions and are computationally intensive. This dissertation focuses on Resonant Tunneling Double-Barrier (RTDB) diodes as the prototype of "quantum devices". A one-electron model and the effective mass approximation are used. By solving numerically the time-dependent Schrodinger equation for Gaussian wavepackets, the various time characteristics of resonant tunneling are probed. These characteristics are usually overlooked in other treatments based on the time-independent Schrodinger equation. The transit time, the build-up time and the exponential decay time are studied. The difference between these various time scales and their relative importance are discussed. A new method that takes into account the finite extent of the electron wavefunction, is proposed to compute the I-V characteristics of such devices. Results indicate a possible explanation for the discrepancy observed between experimental results and previous analyses. The effect of high frequency fields on resonant tunneling is also studied, and a method to determine the intrinsic cut-off frequency is suggested. The role of the effective mass in the determination of the characteristics of RTDB diodes is emphasized throughout this work.

  4. Sulphate reduction in the Aespoe HRL tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Gustafson, G. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Geology; Laaksoharju, M. [ed.; Skaarman, C. [GeoPoint AB, Sollentuna (Sweden); Pedersen, K. [Goeteborg Univ. (Sweden). Dept. of Genetics, Microbiology and Molecular Biology; Rhen, I. [VBB Viak (Sweden); Tullborg, E.L. [Terralogica AB (Sweden); Wallin, B. [Geokema AB (Sweden); Wikberg, P. [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    1995-12-01

    Evidence and indications of sulphate reduction based on geological, hydrogeological, groundwater, isotope and microbial data gathered in and around the Aespoe Hard Rock Laboratory tunnel have been evaluated. This integrated investigation showed that sulphate reduction had taken place in the past but is most likely also an ongoing process. Anaerobic sulphate-reducing bacteria can live in marine sediments, in the tunnel sections under the sea and in deep groundwaters, since there is no access to oxygen. The sulphate-reducing bacteria seem to thrive when the Cl{sup -} concentration of the groundwater is 4000-6000 mg/l. Sulphate reduction is an in situ process but the resulting hydrogen-sulphide rich water can be transported to other locations. A more vigorous sulphate reduction takes place when the organic content in the groundwater is high (>10 mg/l DOC) which is the case in the sediments and in the groundwaters under the sea. Some bacteria use hydrogen as an electron donor instead of organic carbon and can therefore live in deep environments where access to organic material is limited. The sulphate-reducing bacteria seem to adapt to changing flow situations caused by the tunnel construction relatively fast. Sulphate reduction seems to have occurred and will probably occur where conditions are favourable for the sulphate-reducing bacteria such as anaerobic brackish groundwater with dissolved sulphate and organic carbon or hydrogen. 59 refs, 37 figs, 6 tabs.

  5. Tunneling ionization of vibrationally excited nitrogen molecules

    Science.gov (United States)

    Kornev, Aleksei S.; Zon, Boris A.

    2015-09-01

    Ionization of molecular nitrogen plays an important role in the process of light-filament formation in air. In the present paper we theoretically investigated tunneling ionization of the valence 3 σg and 1 πu shells in a N2 molecule using a strong near-infrared laser field. This research is based on our previously proposed theory of anti-Stokes-enhanced tunneling ionization with quantum accounting for the vibrationally excited states of the molecules [A. S. Kornev and B. A. Zon, Phys. Rev. A 86, 043401 (2012), 10.1103/PhysRevA.86.043401]. We demonstrated that if the N2 molecule is ionized from the ground vibrational state, then the contribution of the 1 πu orbital is 0.5%. In contrast, for vibrationally excited states with a certain angle between the light polarization vector and the molecule axis, both shells can compete and even reverse their contributions due to the anti-Stokes mechanism. The structure constants of molecular orbitals are extracted from numerical solutions to the Hartree-Fock equations. This approach correctly takes into account the exchange interaction. Quantum consideration of vibrational motion results in the occurrence of the critical vibrational state, the tunneling ionization from which has the maximum rate. The numbers of the critical vibrational states are different for different valence shells. In addition, quantum description of vibrations changes the rate of ionization from the ground vibrational state by 20%-40% in comparison with the quasiclassical results.

  6. Energy Optimization of Road Tunnel Lighting Systems

    Directory of Open Access Journals (Sweden)

    Ferdinando Salata

    2015-07-01

    Full Text Available A road tunnel is an enclosed and covered infrastructure for the vehicular traffic. Its lighting system provides 24 h of artificial sources only, with a higher amount of electric power used during the day. Due to safety reasons, when there is natural lighting outside the tunnel, the lighting levels in the stretches right after the entrance and before the exit must be high, in order to guide the driver’s eye towards the middle of the tunnel where the luminance must guarantee safe driving, avoid any over-dimensioning of the lighting systems, and produce energy savings. Such effects can be reached not only through the technological advances in the field of artificial lighting sources with high luminous efficiency, but also through new materials for road paving characterized by a higher reflection coefficient than other ordinary asphalts. This case study examines different technical scenarios, analyzing and comparing possible energy and economic savings. Traditional solutions are thus compared with scenarios suggesting the solutions previously mentioned. Special asphalts are interesting from an economic point of view, whereas the high costs of LED sources nowadays represent an obstacle for their implementation.

  7. Tunneling spectra of graphene on copper unraveled.

    Science.gov (United States)

    Zhang, Xin; Stradi, Daniele; Liu, Lei; Luo, Hong; Brandbyge, Mads; Gu, Gong

    2016-06-22

    Scanning tunneling spectroscopy is often employed to study two-dimensional (2D) materials on conductive growth substrates, in order to gain information on the electronic structures of the 2D material-substrate systems, which can lead to insight into 2D material-substrate interactions, growth mechanisms, etc. The interpretation of the spectra can be complicated, however. Specifically for graphene grown on copper, there have been conflicting reports of tunneling spectra. A clear understanding of the mechanisms behind the variability is desired. In this work, we have revealed that the root cause of the variability in tunneling spectra is the variation in graphene-substrate coupling under various experimental conditions, providing a salutary perspective on the important role of 2D material-substrate interactions. The conclusions are drawn from measured data and theoretical calculations for monolayer, AB-stacked bilayer, and twisted bilayer graphene coexisting on the same substrates in areas with and without intercalated oxygen, demonstrating a high degree of consistency. The Van Hove singularities of the twisted graphene unambiguously indicate the Dirac energy between them, lending strong evidence to our assignment of the spectral features. In addition, we have discovered an O-Cu superstructure that has never been observed before.

  8. An air cleaner for road tunnels

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    an air cleaner employing pulse induced plasma chemical process to remove dust and carbon monoxide (CO) in road tunnels is presented, which is composed of mainly a precipitator, a reactor, a flow control system, a power supply and a measurement system. Its performances are studied in simulated air conditions. It is found that the rate of dust removal is dependent on the voltage of the pulse power, the distance between the two dust collecting plates of the electrostatic precipitator,the effective length of the precipitator and the air flow rate in the precipitator, and that of CO removal is affected by the voltage and frequency of the super pulse power, the air flow rate in the reactor and the relative humidity of air. Applying such an cleaner of a proper design to the treatment of polluted air at a flow rate of 7 m/s can achieve the rate of dust removal up to 93 % and that of CO removal up to 72.6 %, which efficiently controls the concentrations of CO and dust under allowable limits. It is implied that the proposed air cleaner is a potential solution to air control in road tunnels, and is prominent for its performances and saving the huge cost of longitudinal ventilation tunnel or vertical vent and ventilation facilities.

  9. Gamma Radiation Tolerance of Magnetic Tunnel Junctions

    Science.gov (United States)

    Ren, Fanghui; Jander, Albrecht; Dhagat, Pallavi; Nordman, Cathy

    2011-10-01

    Determining the radiation tolerance of magnetic tunnel junctions (MTJ), which are the storage elements of non-volatile magnetoresistive random access memories (MRAM), is important for investigating their potential application in space. In this effort, the effect of gamma radiation on MTJs with MgO tunnel barriers was studied. Experimental and control groups of samples were characterized by ex situ measurements of the magnetoresistive hysteresis loops and I-V curves. The experimental group was exposed to gamma rays from a ^60Co source. The samples initially received a dose of 5.9 Mrad (Si) after which they were again characterized electrically and magnetically. Irradiation was then continued for a cumulative dose of 10 Mrad and the devices re-measured. The result shows no change in magnetic properties such as coercivity or exchange coupling due to irradiation. After correcting for differences in temperature at the time of testing, the tunneling magnetoresistance was also found to be unchanged. Thus, it has been determined that MgO-based MTJs are highly tolerant of gamma radiation, particularly in comparison to silicon field-effect transistors which have been shown to degrade with gamma ray exposure even as low as 100 Krad [Zhiyuan Hu. et al., IEEE trans. on Nucl. Sci., vol. 58, 2011].

  10. Chloride Transport in Undersea Concrete Tunnel

    Directory of Open Access Journals (Sweden)

    Yuanzhu Zhang

    2016-01-01

    Full Text Available Based on water penetration in unsaturated concrete of underwater tunnel, a diffusion-advection theoretical model of chloride in undersea concrete tunnel was proposed. The basic parameters including porosity, saturated hydraulic conductivity, chloride diffusion coefficient, initial water saturation, and moisture retention function of concrete specimens with two water-binder ratios were determined through lab-scale experiments. The variation of chloride concentration with pressuring time, location, solution concentration, initial saturation, hydraulic pressure, and water-binder ratio was investigated through chloride transport tests under external water pressure. In addition, the change and distribution of chloride concentration of isothermal horizontal flow were numerically analyzed using TOUGH2 software. The results show that chloride transport in unsaturated concrete under external water pressure is a combined effect of diffusion and advection instead of diffusion. Chloride concentration increased with increasing solution concentration for diffusion and increased with an increase in water pressure and a decrease in initial saturation for advection. The dominant driving force converted with time and saturation. When predicting the service life of undersea concrete tunnel, it is suggested that advection is taken into consideration; otherwise the durability tends to be unsafe.

  11. High- Speed railway lines in Germany: Experience in Tunnelling in Karstic Geology and Discussion oF Tunnel Driving Methods

    Institute of Scientific and Technical Information of China (English)

    Rudolf Pottler

    2004-01-01

    In the course of Deutsche Bahn's new high - speed railway line between Nuremberg and Ingolstadt, a number of tunnels are being constructed, with a total length of about 15 km. One of the longest tunnel is the 7,250 m long Irlahüll tunnel.The tunnel was driven in karst geology. It was not expected that karst phenomena would be so widespread. This forced client, designer and contractor to take a new approach to the project. Different tools were developed to handle the problems on site. Additional site investigations had to be performed to identify karst phenomena in the vicinity of the tunnel. For validating the stability and serviceability of the tunnel, a new way of defining the probability of failure of the construction had to be found. Based on the experience of the tunnel driving at the high - speed railway line in Germany between Nuremberg and Ingolstadt, two different methods of tunnelling are discussed: Drill and blast ( New Austrian Tunnelling Method: NATM) and the use of tunnel boring machines (TBM).

  12. Maximum tunneling velocities in symmetric double well potentials

    CERN Document Server

    Manz, Jörn; Schmidt, Burkhard; Yang, Yonggang

    2014-01-01

    We consider coherent tunneling of one-dimensional model systems in non-cyclic or cyclic symmetric double well potentials. Generic potentials are constructed which allow for analytical estimates of the quantum dynamics in the non-relativistic deep tunneling regime, in terms of the tunneling distance, barrier height and mass (or moment of inertia). For cyclic systems, the results may be scaled to agree well with periodic potentials for which semi-analytical results in terms of Mathieu functions exist. Starting from a wavepacket which is initially localized in one of the potential wells, the subsequent periodic tunneling is associated with tunneling velocities. These velocities (or angular velocities) are evaluated as the ratio of the flux densities versus the probability densities. The maximum velocities are found under the top of the barrier where they scale as the square root of the ratio of barrier height and mass (or moment of inertia), independent of the tunneling distance. They are applied exemplarily to ...

  13. Structural Monitoring of Metro Infrastructure during Shield Tunneling Construction

    Directory of Open Access Journals (Sweden)

    L. Ran

    2014-01-01

    Full Text Available Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.

  14. Structural monitoring of metro infrastructure during shield tunneling construction.

    Science.gov (United States)

    Ran, L; Ye, X W; Ming, G; Dong, X B

    2014-01-01

    Shield tunneling construction of metro infrastructure will continuously disturb the soils. The ground surface will be subjected to uplift or subsidence due to the deep excavation and the extrusion and consolidation of the soils. Implementation of the simultaneous monitoring with the shield tunnel construction will provide an effective reference in controlling the shield driving, while how to design and implement a safe, economic, and effective structural monitoring system for metro infrastructure is of great importance and necessity. This paper presents the general architecture of the shield construction of metro tunnels as well as the procedure of the artificial ground freezing construction of the metro-tunnel cross-passages. The design principles for metro infrastructure monitoring of the shield tunnel intervals in the Hangzhou Metro Line 1 are introduced. The detailed monitoring items and the specified alarming indices for construction monitoring of the shield tunneling are addressed, and the measured settlement variations at different monitoring locations are also presented.

  15. Self-contained instrument for measuring subterranean tunnel wall deflection

    Science.gov (United States)

    Rasmussen, Donald Edgar; Hof, Jr., Peter John

    1978-01-01

    The deflection of a subterranean tunnel is measured with a rod-like, self-contained instrument that is adapted to be inserted into a radially extending bore of the tunnel adjacent an end of the tunnel where the tunnel is being dug. One end of the instrument is anchored at the end of the bore remote from the tunnel wall, while the other end of the intrument is anchored adjacent the end of the wall in proximity to the tunnel wall. The two ends of the instrument are linearly displaceable relative to each other; the displacement is measured by a transducer means mounted on the instrument. Included in the instrument is a data storage means including a paper tape recorder periodically responsive to a parallel binary signal indicative of the measured displacement.

  16. Addressing student models of energy loss in quantum tunnelling

    CERN Document Server

    Wittmann, M C; Bao, L; Wittmann, Micael C.; Morgan, Jeffrey T.; Bao, Lei

    2005-01-01

    We report on a multi-year, multi-institution study to investigate student reasoning about energy in the context of quantum tunnelling. We use ungraded surveys, graded examination questions, individual clinical interviews, and multiple-choice exams to build a picture of the types of responses that students typically give. We find that two descriptions of tunnelling through a square barrier are particularly common. Students often state that tunnelling particles lose energy while tunnelling. When sketching wave functions, students also show a shift in the axis of oscillation, as if the height of the axis of oscillation indicated the energy of the particle. We find inconsistencies between students' conceptual, mathematical, and graphical models of quantum tunnelling. As part of a curriculum in quantum physics, we have developed instructional materials to help students develop a more robust and less inconsistent picture of tunnelling, and present data suggesting that we have succeeded in doing so.

  17. Fixed-gap tunnel junction for reading DNA nucleotides.

    Science.gov (United States)

    Pang, Pei; Ashcroft, Brian Alan; Song, Weisi; Zhang, Peiming; Biswas, Sovan; Qing, Quan; Yang, Jialing; Nemanich, Robert J; Bai, Jingwei; Smith, Joshua T; Reuter, Kathleen; Balagurusamy, Venkat S K; Astier, Yann; Stolovitzky, Gustavo; Lindsay, Stuart

    2014-12-23

    Previous measurements of the electronic conductance of DNA nucleotides or amino acids have used tunnel junctions in which the gap is mechanically adjusted, such as scanning tunneling microscopes or mechanically controllable break junctions. Fixed-junction devices have, at best, detected the passage of whole DNA molecules without yielding chemical information. Here, we report on a layered tunnel junction in which the tunnel gap is defined by a dielectric layer, deposited by atomic layer deposition. Reactive ion etching is used to drill a hole through the layers so that the tunnel junction can be exposed to molecules in solution. When the metal electrodes are functionalized with recognition molecules that capture DNA nucleotides via hydrogen bonds, the identities of the individual nucleotides are revealed by characteristic features of the fluctuating tunnel current associated with single-molecule binding events.

  18. Pair tunneling of two atoms out of a trap

    Science.gov (United States)

    Rontani, Massimo

    2013-10-01

    A simple theory for the tunneling of two cold atoms out of a trap in the presence of an attractive contact force is developed. Two competing decay channels, for single-atom and bound-pair tunneling, respectively, contribute independently to the decay law of the mean atom number in the trap. The single-atom tunneling rate is obtained through the quasiparticle wave function formalism. For pair tunneling an effective equation for the center-of-mass motion is derived, so the calculation of the corresponding tunneling rate is again reduced to a simpler one-body problem. The predicted dependence of tunneling rates on the interaction strength qualitatively agrees with a recent measurement of the two-atom decay time [G. Zürn, A. N. Wenz, S. Murmann, T. Lompe, and S. Jochim, arXiv:1307.5153].

  19. Microwave-induced co-tunneling in single electron tunneling transistors

    DEFF Research Database (Denmark)

    Ejrnaes, M.; Savolainen, M.; Manscher, M.;

    2002-01-01

    The influence of microwaves on the co-tunneling in single electron tunneling transistors has been investigated as function of frequency and power in the temperature range from 150 to 500 mK. All 20 low frequency connections and the RF line were filtered, and the whole cryostat was suspended...... fixed at maximum Coulomb blockade. With the microwave signal applied to one side of the transistor, we find that the conductance increases linearly with T-2 and microwave power. (C) 2002 Elsevier Science B.V. All rights reserved....

  20. In-mine (tunnel-to-tunnel) electrical resistance tomography in South African platinum mines

    CSIR Research Space (South Africa)

    Van Schoor, Abraham M

    2009-12-01

    Full Text Available is considered here; that is, tunnels surrounding an area of interest. These 176 studies, however, essentially represented once-off trial surveys. Sasaki and Matsuo 177 exploited a tunnel-to-surface geometry for ERT investigations in a copper-scarn mine 178... 357 358 CASE STUDY ? WATERVAL PLATINUM MINE 359 Site description 360 In May 2009, an ERT trial survey was conducted at Anglo Platinum?s Waterval Mine 361 near Rustenburg. Waterval Mine is a bord-and-pillar, mechanised operation where the 362 UG2...

  1. Tunneling Anisotropic Magnetoresistance in Co/AlOx/Au Tunnel Junctions

    CERN Document Server

    Liu, R S; Canali, C M; Samuelson, L; Pettersson, H

    2008-01-01

    We observe spin-valve-like effects in nano-scaled thermally evaporated Co/AlOx/Au tunnel junctions. The tunneling magnetoresistance is anisotropic and depends on the relative orientation of the magnetization direction of the Co electrode with respect to the current direction. We attribute this effect to a two-step magnetization reversal and an anisotropic density of states resulting from spin-orbit interaction. The results of this study points to future applications of novel spintronics devices involving only one ferromagnetic layer.

  2. ROCK MASS DAMAGED ZONE CAUSED BY BLASTING DURING TUNNEL EXCAVATION

    OpenAIRE

    Hrvoje Antičević; Mario Dobrilović; Hrvoje Perković

    2012-01-01

    Design of underground spaces, including tunnels, and repositories for radioactive waste include the application of the same or similar technologies. Tunnel excavation by blasting inevitably results in the damage in the rock mass around the excavation profile. The damage in the rock mass immediately next to the tunnel profile emerges as the expanding of the existing cracks and the appearance of new cracks, i.e. as the change of the physical and-mechanical properties of the rock mass. Concernin...

  3. Giant tunnel-electron injection in nitrogen-doped graphene

    DEFF Research Database (Denmark)

    Lagoute, Jerome; Joucken, Frederic; Repain, Vincent

    2015-01-01

    Scanning tunneling microscopy experiments have been performed to measure the local electron injection in nitrogen-doped graphene on SiC(000) and were successfully compared to ab initio calculations. In graphene, a gaplike feature is measured around the Fermi level due to a phonon-mediated tunneling...... and at carbon sites. Nitrogen doping can therefore be proposed as a way to improve tunnel-electron injection in graphene....

  4. High pressure unlined tunnels: Exemplified with Nye Tyin Hydropower Project

    OpenAIRE

    Belayneh, Dawit Tadesse

    2013-01-01

    Topographic condition in Norway is favorable for the development of hydropower and more than 99% of annual production of energy in Norway is generated from hydropower. Unlined tunnels and underground powerhouses have been constructed starting from the end of World War I in 1919. From the valuable experience gained through the design, construction and operation of tunnels in the past 100 years in Norway, at the present the high head unlined pressure tunnels have been developed up to reach 104...

  5. Fermion Tunnelling of a New Form Finslerian Black Hole

    Institute of Scientific and Technical Information of China (English)

    LIN Kai; YANG Shu-Zheng

    2009-01-01

    We improve the fermion tunnelling theory proposed by Kerner and Mann, and research into the fermion tunnelling radiation from a Finslerian black hole. The Finsler black hole put forward by Rutz is a solution of Einstein's vacuum field equations in Finsler theory. We study the radiation from the black hole with a semi-classical method, and the result proves that the tunnelling rate depends on the tangent vector.

  6. Quantum tunneling splittings from path-integral molecular dynamics

    Science.gov (United States)

    Mátyus, Edit; Wales, David J.; Althorpe, Stuart C.

    2016-03-01

    We illustrate how path-integral molecular dynamics can be used to calculate ground-state tunnelling splittings in molecules or clusters. The method obtains the splittings from ratios of density matrix elements between the degenerate wells connected by the tunnelling. We propose a simple thermodynamic integration scheme for evaluating these elements. Numerical tests on fully dimensional malonaldehyde yield tunnelling splittings in good overall agreement with the results of diffusion Monte Carlo calculations.

  7. Electron tunneling and point contact Andreev reflection studies of superconductors

    Science.gov (United States)

    Dai, Wenqing

    The energy gap is the most fundamental property of a superconductor. Electron tunneling spectroscopy and point contact spectroscopy (PCS) are powerful techniques for studying the density of states and energy gap features of superconductors. Two different superconducting systems, multiband superconductor MgB2 and proximity induced topological superconductor NbSe2/Bi 2Se3 heterostructures were studied using either quasiparticle tunneling in planar tunnel junctions or PCS in this work. (Abstract shortened by ProQuest.).

  8. Unification of Filled Function and Tunnelling Function in Global Optimization

    Institute of Scientific and Technical Information of China (English)

    Wei Wang; Yong-jian Yang; Lian-sheng Zhang

    2007-01-01

    In this paper, two auxiliary functions for global optimization are proposed. These two auxiliary functions possess all characters of tunnelling functions and filled functions under certain general assumptions.Thus, they can be considered as the unification of filled function and tunnelling function. Moreover, the process of tunneling or filling for global optimization can be unified as the minimization of such auxiliary functions.Result of numerical experiments shows that such two auxiliary functions are effective.

  9. Tunneling Time of Particles Through a Potential Barrier

    Institute of Scientific and Technical Information of China (English)

    LI Chun-Fang; WANG Qi

    2000-01-01

    A new tunneling time is proposed by introducing the transfer speed of energy carried by tunneling particles. This speed is similar to the energy transfer speed in electromagnetism, and with the tunneling time, the well-known superluminality may be avoided. The low energy limit, the critical limit, and the opaque limit are considered,which are physically meaningful. Comparisons with dwell time and Biittiker and Landauer's semiclassical time are also made.

  10. Simulations of Resonant Intraband and Interband Tunneling Spin Filters

    Science.gov (United States)

    Ting, David; Cartoixa-Soler, Xavier; McGill, T. C.; Smith, Darryl L.; Schulman, Joel N.

    2001-01-01

    This viewgraph presentation reviews resonant intraband and interband tunneling spin filters It explores the possibility of building a zero-magnetic-field spin polarizer using nonmagnetic III-V semiconductor heterostructures. It reviews the extensive simulations of quantum transport in asymmetric InAs/GaSb/AlSb resonant tunneling structures with Rashba spin splitting and proposes a. new device concept: side-gated asymmetric Resonant Interband Tunneling Diode (a-RITD).

  11. Acute cerebellar ataxia

    Science.gov (United States)

    Cerebellar ataxia; Ataxia - acute cerebellar; Cerebellitis; Post-varicella acute cerebellar ataxia; PVACA ... Acute cerebellar ataxia in children, particularly younger than age 3, may occur several weeks after an illness caused by a virus. ...

  12. Acute arterial occlusion - kidney

    Science.gov (United States)

    Acute renal arterial thrombosis; Renal artery embolism; Acute renal artery occlusion; Embolism - renal artery ... kidney can often result in permanent kidney failure. Acute arterial occlusion of the renal artery can occur after injury or trauma to ...

  13. Coronal plane radiographic evaluation of the single TightRope technique in the treatment of acute acromioclavicular joint injury.

    Science.gov (United States)

    Yi, Young; Kim, Jeong Woo

    2015-10-01

    This study aimed to demonstrate the technical aspects of the single TightRope (Arthrex, Naples, FL, USA) procedure for acute acromioclavicular-coracoclavicular joint dislocation, identify the predictive factors influencing its outcome, and assess and validate the significance of specific radiologic parameters. We reviewed true anteroposterior shoulder radiographs of 62 consecutive patients who had undergone surgical reconstruction using TightRope for an acute acromioclavicular-coracoclavicular injury. All patients were followed up for at least 12 months between October 2009 and March 2012 and were divided into dissociated or nondissociated groups according to their surgical outcome. We measured the clavicle tunnel anteroposterior angle, distal clavicular tunnel placement, and tunnel-to-medial coracoid ratio, and compared the parameters in each group after a satisfactory intraclass correlation coefficient reliability test result. The angles of patients in the dissociated group were more acute compared with the angles of those in the nondissociated group, which were perpendicular, as verified statistically using the paired t test. The difference in the distal clavicular tunnel placement and tunnel-to-medial coracoid ratio between the groups was not significant. Therefore, tunnel placement is not influenced by coracoclavicular dissociation. The clavicle tunnel anteroposterior angle can be used as a predictor of surgical outcome in coracoclavicular augmentation surgery. The surgeon should strive to place a perpendicular hole from the clavicle to the coracoid process for the TightRope fixation to enable a successful reconstruction of the acute acromioclavicular-coracoclavicular injury. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  14. Simulation of smoke flow and longitudinal ventilation in tunnel fire

    Institute of Scientific and Technical Information of China (English)

    YANG Gao-shang; AN Yong-lin; PENG Li-min; ZHANG Jin-hua

    2006-01-01

    Understanding the characteristics of smoke flow in tunnel fire is very important for tunnel safety. The characteristics of tunnel fire were analyzed. The smoke development in different situations of an engineering example was simulated using commercial CFD software PHOENICS 3.5 by field modeling method. The spreading rules and characteristics of concentration field and temperature field of smoke flow with different longitudinal ventilation speeds were studied, which may provide the theoretical background for evacuation design in tunnel fire. The effective measures of fire rescue and crowd evacuation were also described.

  15. Measuring voltage transients with an ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We use an ultrafast scanning tunneling microscope to resolve propagating voltage transients in space and time. We demonstrate that the previously observed dependence of the transient signal amplitude on the tunneling resistance was only caused by the electrical sampling circuit. With a modified...... circuit, where the tunneling tip is directly connected to the current amplifier of the scanning tunneling microscope, this dependence is eliminated. Ail results can be explained with coupling through the geometrical capacitance of the tip-electrode junction. By illuminating the current...

  16. Tunnel production enhances quality in organic carrot seed production

    DEFF Research Database (Denmark)

    Deleuran, L C; Boelt, B

    2009-01-01

    water supply and thereby introduce drought at proven optimum times, restrict geneflow through insect- and pollen-proof netting, raise the temperature to prolong the growing season and hence the crop duration, and reduce pest attack by preventing pest entrance to the tunnel. In an experiment, tunnel......In Denmark, organic vegetable seed production is possible for some of the late-maturing species when the maturing is performed in lightweight tunnels which are also relevant for the isolation of small-scale production. The tunnel system offers several advantages, e.g., it is possible to control...

  17. Cubital tunnel syndrome: A report of two cases

    Directory of Open Access Journals (Sweden)

    Farhana Ebrahim Suleman

    2012-06-01

    Full Text Available Cubital tunnel syndrome is the second most common peripheral neuropathy of the upper limb. This is due to the anatomy of the tunnel, the physiological changes that the nerve undergoes during elbow flexion, as well as pathological conditions that occur within the tunnel. We present two cases of ulnar neuropathy occurring at the level of the cubital tunnel, demonstrating that this entity may occur owing to an identifiable cause or may show only signal alteration without a visible cause on MRI.

  18. Computational Wind Tunnel: A Design Tool for Rotorcraft Project

    Data.gov (United States)

    National Aeronautics and Space Administration — During initial design studies, parametric variation of vehicle geometry is routine. In addition, rotorcraft engineers traditionally use the wind tunnel to evaluate...

  19. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-01-01

    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

  20. Analysis of an Underground Structure Settlement Risk due to Tunneling

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammad Javad; Ghodrat, Hadi; Firouzianbandpey, Sarah

    2010-01-01

    The tunnel of the Tabriz urban railway line 2 (TURL2), Iran, will pass through an underground commercial center on its way. Too little distance between the tunnel crown and the underground structure foundation will probably cause collapse or excessive settlement during the tunnel construction based...... of the underground commercial center structure settlement is estimated using both empirical and numerical methods. The settlement risk level of the commercial center structure is determined based on presented definitions about risk classification of various types of structures. Consequently, tunneling processes...

  1. Quantum Tunnelling to the Origin and Evolution of Life.

    Science.gov (United States)

    Trixler, Frank

    2013-08-01

    Quantum tunnelling is a phenomenon which becomes relevant at the nanoscale and below. It is a paradox from the classical point of view as it enables elementary particles and atoms to permeate an energetic barrier without the need for sufficient energy to overcome it. Tunnelling might seem to be an exotic process only important for special physical effects and applications such as the Tunnel Diode, Scanning Tunnelling Microscopy (electron tunnelling) or Near-field Optical Microscopy operating in photon tunnelling mode. However, this review demonstrates that tunnelling can do far more, being of vital importance for life: physical and chemical processes which are crucial in theories about the origin and evolution of life can be traced directly back to the effects of quantum tunnelling. These processes include the chemical evolution in stellar interiors and within the cold interstellar medium, prebiotic chemistry in the atmosphere and subsurface of planetary bodies, planetary habitability via insolation and geothermal heat as well as the function of biomolecular nanomachines. This review shows that quantum tunnelling has many highly important implications to the field of molecular and biological evolution, prebiotic chemistry and astrobiology.

  2. Structural Safety Assessment of Existing Multiarch Tunnel: A Case Study

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2017-01-01

    Full Text Available Structural health assessment is one of the key activities in maintaining the performance of a tunnel during its service life. Due to the development of modern detection technology, comprehensive structural health assessment system is being established for operating tunnels. To evaluate the actual operational state of Shitigou tunnel, overall detection of the liner crack, tunnel seepage, and liner void was conducted by employing the modern detection technology, such as crack width monitoring technology, concrete strength monitoring technology, and electromagnetic wave nondestructive monitoring technology. Through the statistical analysis of the detection results, the distribution characteristic, development law, and damage grade of structural defects were obtained. Tunnel liner cracks are mainly located on the middle wall; serious water leakage is encountered on the side wall, middle wall, and vault; the strength of foundation and liner structure of left tunnel does not meet the design requirement; the liner voids are mostly located at the tunnel entrance section, especially, on the tunnel vault; and the proportion of influence factors of structural defects should be considered. The research results presented for this study can serve as references for effective design and health assessment of existing multiarch tunnel projects.

  3. Pictorial essay: Role of ultrasound in failed carpal tunnel decompression

    Directory of Open Access Journals (Sweden)

    Rajesh Botchu

    2012-01-01

    Full Text Available USG has been used for the diagnosis of carpal tunnel syndrome. Scarring and incomplete decompression are the main causes for persistence or recurrence of symptoms. We performed a retrospective study to assess the role of ultrasound in failed carpal tunnel decompression. Of 422 USG studies of the wrist performed at our center over the last 5 years, 14 were for failed carpal tunnel decompression. Scarring was noted in three patients, incomplete decompression in two patients, synovitis in one patient, and an anomalous muscle belly in one patient. No abnormality was detected in seven patients. We present a pictorial review of USG findings in failed carpal tunnel decompression.

  4. Automatic control study of the icing research tunnel refrigeration system

    Science.gov (United States)

    Kieffer, Arthur W.; Soeder, Ronald H.

    1991-01-01

    The Icing Research Tunnel (IRT) at the NASA Lewis Research Center is a subsonic, closed-return atmospheric tunnel. The tunnel includes a heat exchanger and a refrigeration plant to achieve the desired air temperature and a spray system to generate the type of icing conditions that would be encountered by aircraft. At the present time, the tunnel air temperature is controlled by manual adjustment of freon refrigerant flow control valves. An upgrade of this facility calls for these control valves to be adjusted by an automatic controller. The digital computer simulation of the IRT refrigeration plant and the automatic controller that was used in the simulation are discussed.

  5. Rocket Plume Scaling for Orion Wind Tunnel Testing

    Science.gov (United States)

    Brauckmann, Gregory J.; Greathouse, James S.; White, Molly E.

    2011-01-01

    A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies.

  6. Atomic Tunnelling Dynamics of Two Squeezed Bose-Einstein Condensates

    Institute of Scientific and Technical Information of China (English)

    LI Jin-Hui; KUANG Le-Man

    2003-01-01

    In this paper, tunnelling dynamics of squeezed Bose-Einstein condensates (BEC's) in the presence of the nonlinear self-interaction of each species, the interspecies nonlinear interaction, and the Josephson-like tunnelling interaction is investigated by using the second quantization approach. The influence of BEC squeezing on macroscopic quantum self-trapping (MQST) and quantum coherent atomic tunnelling is analyzed in detail. It is shown that the MQST and coherent atomic tunnelling between two squeezed BEC's can be manipulated through changing squeezing amplitude and squeezing phase of BEC squeezed states.

  7. Superconducting Tunnel Junction Arrays for UV Photon Detection Project

    Data.gov (United States)

    National Aeronautics and Space Administration — An innovative method is described for the fabrication of superconducting tunnel junction (STJ) detector arrays offering true "three dimensional" imaging throughout...

  8. Proceedings of the meeting on tunneling reaction and low temperature chemistry, 98 August. Tunneling reaction and its theory

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Tetsuo; Aratono, Yasuyuki; Ichikawa, Tsuneki; Shiotani, Masaru [eds.

    1998-10-01

    Present report is the proceedings of the 4th Meeting on Tunneling Reaction and Low Temperature Chemistry held in August 3 and 4, 1998. The main subject of the meeting is `Tunneling Reaction and Its Theory`. In the present meeting the theoretical aspects of tunneling phenomena in the chemical reaction were discussed intensively as the main topics. Ten reports were presented on the quantum diffusion of muon and proton in the metal and H{sub 2}{sup -} anion in the solid para-hydrogen, the theory of tunnel effect in the nuclear reaction and the tunneling reaction in the organic compounds. One special lecture was presented by Prof. J. Kondo on `Proton Tunneling in Solids`. The 11 of the presented papers are indexed individually. (J.P.N.)

  9. Proceedings of the meeting on tunneling reaction and low temperature chemistry, 97 October. Tunneling reaction and quantum medium

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Tetsuo; Aratono, Yasuyuki; Ichikawa, Tsuneki; Shiotani, Masaru [eds.

    1998-02-01

    Present report is the proceedings of the 3rd Meeting on Tunneling Reaction and Low Temperature Chemistry held in Oct. 13 and 14, 1997. The main subject of the meeting is `Tunneling Reaction and Quantum Medium`. In the meeting, the physical and chemical phenomena in the liquid helium such as quantum nucleation, spectroscopy of atoms and molecules, and tunneling abstraction reaction of tritium atom were discussed as the main topics as well as the tunneling reactions in the solid hydrogen and organic compounds. Through the meetings held in 1995, 1996, and 1997, the tunneling phenomena proceeding at various temperatures (room temperature to mK) in the wide fields of chemistry, biology, and physics were discussed intensively and the importance of the tunneling phenomena in the science has been getting clear. The 12 of the presented papers are indexed individually. (J.P.N.)

  10. Proceedings of the meeting on tunneling reaction and low temperature chemistry, 97 October. Tunneling reaction and quantum medium

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, Tetsuo; Aratono, Yasuyuki; Ichikawa, Tsuneki; Shiotani, Masaru [eds.

    1998-02-01

    Present report is the proceedings of the 3rd Meeting on Tunneling Reaction and Low Temperature Chemistry held in Oct. 13 and 14, 1997. The main subject of the meeting is `Tunneling Reaction and Quantum Medium`. In the meeting, the physical and chemical phenomena in the liquid helium such as quantum nucleation, spectroscopy of atoms and molecules, and tunneling abstraction reaction of tritium atom were discussed as the main topics as well as the tunneling reactions in the solid hydrogen and organic compounds. Through the meetings held in 1995, 1996, and 1997, the tunneling phenomena proceeding at various temperatures (room temperature to mK) in the wide fields of chemistry, biology, and physics were discussed intensively and the importance of the tunneling phenomena in the science has been getting clear. The 12 of the presented papers are indexed individually. (J.P.N.)

  11. Acute Appendicitis

    DEFF Research Database (Denmark)

    Tind, Sofie; Qvist, Niels

    2017-01-01

    BACKGROUND: The classification of acute appendicitis (AA) into various grades is not consistent, partly because it is not clear whether the perioperative or the histological findings should be the foundation of the classification. When comparing results from the literature on the frequency...... patients were included. In 116 (89 %) of these cases, appendicitis was confirmed histological. There was low concordance between the perioperative and histological diagnoses, varying from 16 to 76 % depending on grade of AA. Only 44 % of the patients receiving antibiotics postoperatively had a positive...... peritoneal fluid cultivation. CONCLUSION: There was a low concordance in clinical and histopathological diagnoses of the different grades of appendicitis. Perioperative cultivation of the peritoneal fluid as a standard should be further examined. The potential could be a reduced postoperative antibiotic use...

  12. An innovative band-to-band tunneling analytical model and implications in compact modeling of tunneling-based devices

    Science.gov (United States)

    De Michielis, L.; Daǧtekin, N.; Biswas, A.; Lattanzio, L.; Selmi, L.; Luisier, M.; Riel, H.; Ionescu, A. M.

    2013-09-01

    In this paper, an analytical band-to-band tunneling model is proposed, validated by means of drift-diffusion simulation and comparison with experimental data, implemented in Verilog-A, and finally proven with SPICE simulator through simulation of circuits featuring tunneling diodes. The p-n junction current calculation starts from a non-local Band-to-Band tunneling theory including the electron-phonon interaction and therefore it is particularly suited for indirect semiconductor materials such as silicon- or germanium-based interband tunneling devices.

  13. Rational Design of Tunnel Supports: Tunnel Support Loading Caused by Rock Failure

    Science.gov (United States)

    1975-05-01

    Minerale , Vol. 41; No. 1, Janvier, pp. 78-92, No. 4, Avril, pp. 313-315, 1959. Translation by C, Pairhurst, University of Nottingham Mining...G,: "Calcul du revetement des tunnels creuses dans des terrains presentant des deformations differees," Industrie Minerale , pp. 13-18

  14. Tunneling processes and charge accumulation in triple barrier resonant tunneling structures

    Energy Technology Data Exchange (ETDEWEB)

    Macks, L.D.; Brown, S.A.; Clark, R.G.; Starrett, R.P. [University of NSW, Sydney, NSW (Australia). National Pulsed Magnet Laboratory, School of Physics; Reed, M.A; Deshpande, M. R. [Yale University, New Haven, Conneticutt (United States). Departments of Electrical Engineering and Applied Physics; Frensley, W.R. [University of Texas at Dallas, Richardson, Texas (United States). Eric Jonsson School of Electrical Engineering and Computer Science

    1996-12-31

    Tunneling processes in semiconductor double barrier (single quantum well) resonant tunneling structures have been studied in great detail since the pioneering experiments of Chang, Esaki and Tsu. We present a study of tunneling processes in GaAs/AlAs triple barrier (double quantum well) structures, which demonstrates the critical role played by the second well. In sample I, when the emitter and first well are on resonance, the lowest level in the second well is at lower energy and electrons tunnel freely through the structure. At the same resonance condition in sample II, the level in the second well is at higher energy, thus the second well appears as part of a thick collector barrier and charge accumulates in the first well. As the bias voltage is further increased, a `double resonance` condition (simultaneous alignment of both well levels with occupied emitter states) is achieved and the accumulated charge flows freely through the structure to the collector. The double resonance condition is then lost due to the resulting potential redistribution. As a mechanism for limiting the amount of charge accumulation, a multiple resonance is unique to multiple quantum well structures, and we believe it to be identified for the first time in the experiments reported here Truncated abstract. 2 refs.

  15. Idiopathic Carpal Tunnel Syndrome: Evaluation of the Depth of the Carpal Tunnel by Ultrasonography.

    Science.gov (United States)

    Elsaman, Ahmed Mohammed Mahrous Yousif; Thabit, Mohamed Nasreldin; Radwan, Ahmed Roshdy Al-Agamy; Ohrndorf, Sarah

    2015-11-01

    The objective of the work described here was to evaluate the depth of the carpal tunnel (DCT) in patients with idiopathic carpal tunnel syndrome (CTS) and healthy volunteers by ultrasonography (US), through measurement of the distance from the flexor retinaculum to the surface of the capitate bone at the carpal tunnel outlet, and compare it with other ultrasonographic and electrophysiologic parameters in CTS. The study was conducted in 60 non-diabetic patients with idiopathic carpal tunnel syndrome (unilateral n = 37, bilateral n = 23) evidenced by electrophysiologic diagnosis according to the criteria of the American Association of Electrodiagnostic Medicine (AAEM). Furthermore, 40 hands from 20 healthy volunteers were examined. Median nerve cross-sectional area (CSA); flattening ratio (FR), the ratio of the length to the width of the median nerve; and DCT at the canal outlet were measured for all participants. The mean age was 35.6 ± 9.48 y. The female-to-male ratio was 47:13 in the CTS patients. The sensitivity and specificity were 82% and 95% for CSA, 75% and 60% for FR and 75% and 87.5% for DCT, respectively. Differences between patients and healthy controls were significant for all three parameters, greatest for DCT, followed by CSA and then FR. We conclude that DCT increased in CTS and this new parameter is comparable in sensitivity and specificity to CSA and FR. DCT increased independently of the cause of the CTS (decrease in size of canal or increase in contents).

  16. Analysis of tunnel lining behaviour in soft soil during the construction stage, Second Heinenoord Tunnel

    NARCIS (Netherlands)

    Oosterhout, G.P.C. van; Blom, C.B.M.; Jovanovic, P.S.

    1999-01-01

    The paper addresses observations of the structural behaviour of the Tweede Heine-noordtunnel, a shield-driven tunnel in typical Dutch soft soils. Two rings were equipped with structural monitoring instrumentation. The measurements have shown that the assembly of the rings causes very significant ini

  17. Nano-ADEPT Aeroloads Wind Tunnel Test

    Science.gov (United States)

    Smith, Brandon; Yount, Bryan; Kruger, Carl; Brivkalns, Chad; Makino, Alberto; Cassell, Alan; Zarchi, Kerry; McDaniel, Ryan; Ross, James; Wercinski, Paul; Venkatapathy, Ethiraj; Swanson, Gregory; Gold, Nili

    2016-01-01

    A wind tunnel test of the Adaptable Deployable Entry and Placement Technology (ADEPT) was conducted in April 2015 at the US Army's 7 by10 Foot Wind Tunnel located at NASA Ames Research Center. Key geometric features of the fabric test article were a 0.7 meter deployed base diameter, a 70 degree half-angle forebody cone angle, eight ribs, and a nose-to-base radius ratio of 0.7. The primary objective of this wind tunnel test was to obtain static deflected shape and pressure distributions while varying pretension at dynamic pressures and angles of attack relevant to entry conditions at Earth, Mars, and Venus. Other objectives included obtaining aerodynamic force and moment data and determining the presence and magnitude of any dynamic aeroelastic behavior (buzz/flutter) in the fabric trailing edge. All instrumentation systems worked as planned and a rich data set was obtained. This paper describes the test articles, instrumentation systems, data products, and test results. Four notable conclusions are drawn. First, test data support adopting a pre-tension lower bound of 10 foot pounds per inch for Nano-ADEPT mission applications in order to minimize the impact of static deflection. Second, test results indicate that the fabric conditioning process needs to be reevaluated. Third, no flutter/buzz of the fabric was observed for any test condition and should also not occur at hypersonic speeds. Fourth, translating one of the gores caused ADEPT to generate lift without the need for a center of gravity offset. At hypersonic speeds, the lift generated by actuating ADEPT gores could be used for vehicle control.

  18. Tunneling conductivity in composites of attractive colloids.

    Science.gov (United States)

    Nigro, B; Grimaldi, C; Miller, M A; Ryser, P; Schilling, T

    2012-04-28

    In conductor-insulator nanocomposites in which conducting fillers are dispersed in an insulating matrix, the electrical connectedness is established by inter-particle tunneling or hopping processes. These systems are intrinsically non-percolative and a coherent description of the functional dependence of the conductivity σ on the filler properties, and in particular of the conductor-insulator transition, requires going beyond the usual continuum percolation approach by relaxing the constraint of a fixed connectivity distance. In this article, we consider dispersions of conducting spherical particles which are connected to all others by tunneling conductances and which are subjected to an effective attractive square-well potential. We show that the conductor-insulator transition at low contents φ of the conducting fillers does not determine the behavior of σ at larger concentrations, in striking contrast to what is predicted by percolation theory. In particular, we find that at low φ the conductivity is governed almost entirely by the stickiness of the attraction, while at larger φ values σ depends mainly on the depth of the potential well. As a consequence, by varying the range and depth of the potential while keeping the stickiness fixed, composites with similar conductor-insulator transitions may display conductivity variations of several orders of magnitude at intermediate and large φ values. By using a recently developed effective medium theory and the critical path approximation, we explain this behavior in terms of dominant tunneling processes which involve inter-particle distances spanning different regions of the square-well fluid structure as φ is varied. Our predictions could be tested in experiments by changing the potential profile with different depletants in polymer nanocomposites.

  19. Imaging standing surface plasmons by photon tunneling

    Science.gov (United States)

    Passian, A.; Lereu, A. L.; Wig, A.; Meriaudeau, F.; Thundat, T.; Ferrell, T. L.

    2005-04-01

    We present a direct method for optically exciting and imaging delocalized standing surface plasmons in thin metal films. We show theoretically that when imaging the field of the plasmons with a photon scanning tunneling microscope, the presence of the dielectric probe has a negligible effect on the surface modes of the metal film. We demonstrate that plasmon interference can be sustained in arbitrarily large regions of the metal film in comparison to the excitation wavelength. This knowledge can be important when seeking the relative distance between two scattering centers such as the presence of micron or submicron structures.

  20. Optical isolation via unidirectional resonant photon tunneling

    CERN Document Server

    Moccia, Massimo; Galdi, Vincenzo; Alu', Andrea; Engheta, Nader

    2013-01-01

    We show that tri-layer structures combining epsilon-negative and magneto-optical material layers can exhibit unidirectional resonant photon tunneling phenomena that can discriminate between circularly-polarized (CP) waves of given handedness impinging from opposite directions, or between CP waves with different handedness impinging from the same direction. This physical principle may be utilized to design compact optical isolators for CP waves. Within this framework, we derive simple analytical conditions and design formulae, and quantitatively assess the isolation performance, also taking into account the unavoidable imperfections and nonidealities.