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Sample records for acute tarsal tunnel

  1. Tarsal Tunnel Syndrome

    ... and nerves. One of these structures is the posterior tibial nerve, which is the focus of tarsal tunnel ... syndrome is a compression, or squeezing, on the posterior tibial nerve that produces symptoms anywhere along the path ...

  2. Management of tarsal tunnel syndrome: report of seven cases

    Flavio A.P. Settanni

    1994-12-01

    Full Text Available Seven patients with clinical and electroneurographic evidence of tarsal tunnel syndrome were managed surgically, after failed attempts for non-surgical treatment. Post-operative results were more satisfactory than the previous responses to non-surgical therapies. Tarsal tunnel syndrome appears to respond better to surgical intervention than to conservative management.

  3. ANALYSIS OF TARSAL TUNNEL SYNDROME USING IMAGE CORRELATION

    Amarjot Singh; S.N. Omkar

    2013-01-01

    Tarsal tunnel syndrome (TTS), also known as posterior tibial neuralgia is a painful disorder of the foot. It is a medical condition arising due to the compression of the tibial nerve in the tarsal tunnel, resulting in numbness, parenthesis and muscle weakness in foot. A number of imaging methodologies such as ultrasound as well as MRI imaging has been used in the past in order to analyze the strain pattern of gastrocnemius tendon and aponeurosis from the surface of the skin without analyzing ...

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

    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 anterior tarsal tunnel syndrome: a case report].

    Milants, C; Wang, F C; Gomulinski, L; Ledon, F; Petrover, D; Bonnet, R; Crielaard, J M; Kaux, J F

    2015-01-01

    The anterior tarsal tunnel syndrome is a rare entrapment neuropathy of the deep peroneal nerve beneath the inferior extensor retinaculum of the ankle. It is frequently unrecognized and may lead to misdiagnosis and delayed treatment. We report the case of a 77 year old patient complaining of symptoms of an anterior tarsal tunnel syndrome with neuropathic pain located at the dorsal part of the foot, without any sensorimotor loss. The ENMG was in favour of a motor impairment of the deep peroneal nerve. MRI exploration of the ankle showed a millimetric bony overgrowth of the upper pole of the navicular bone, irritative to the deep peroneal nerve. Infiltration at overgrowth of the navicular provided a partial and temporary decrease in pain symptoms. Surgical nerve decompression was then considered. PMID:26376569

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

    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.

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

    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.

  8. ANALYSIS OF TARSAL TUNNEL SYNDROME USING IMAGE CORRELATION

    Amarjot Singh

    2013-11-01

    Full Text Available Tarsal tunnel syndrome (TTS, also known as posterior tibial neuralgia is a painful disorder of the foot. It is a medical condition arising due to the compression of the tibial nerve in the tarsal tunnel, resulting in numbness, parenthesis and muscle weakness in foot. A number of imaging methodologies such as ultrasound as well as MRI imaging has been used in the past in order to analyze the strain pattern of gastrocnemius tendon and aponeurosis from the surface of the skin without analyzing the internal tendons. The DIC code developed, computes the in-plane strain with a correlation function using pictures taken before and after stretching, using a CCD camera. The shift between the initial picture and subsequent one is evaluated by cross-correlation using FFT. This paper gives in detail description of the preprocessing steps necessary to extract Zone of Interest from the two images. The effects of stretching on the superficial components of the tibial nerve, the posterior tibial artery and vein, and the tibialis posterior, flexor digitorum longus and flexor hallucis longus tendons in the calf and foot are studied.

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

    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.

  10. Bilateral Tarsal Tunnel Syndrome Due To Bilateral Lipoma: A Case Report

    C. Eren CANSÜ, İstemi YÜCEL, Kutay ÖZTURAN

    2010-11-01

    Full Text Available Tarsal tunnel syndrome is an entrapment neuropathy of posterior tibial nerve under the flexorretinaculum. Patients generally present with paresthesias on the plantar side of foot and fingersand in the distal kruris.The causes of tarsal tunnel syndrome are space occupying lesions within or around the tunnelwhich exert pressure to the nerve, ankle deformities, systemic illnesses, trauma or lesions ofthe nerve itself.In this study a case of tarsal tunnel syndrome due to bilateral lipoma which was treated surgicallyis presented.

  11. Lumbosacral radiculopathy, reflex sympathetic dystrophy and tarsal tunnel syndrome: an unusual presentation.

    Chodoroff, B; Ball, R D

    1985-03-01

    This case documents a patient with lumbosacral radiculopathy, reflex sympathetic dystrophy, and tarsal tunnel syndrome affecting one extremity. After lumbar laminectomy for L5-S1 radiculopathy, the patient developed foot pain diagnosed as secondary to reflex sympathetic dystrophy. Because of increasing foot pain despite long-term conservative therapy, the patient underwent further evaluation, including electrodiagnostic studies leading to the diagnosis of a superimposed tarsal tunnel syndrome. Following surgical decompression, pain decreased. Because of the unusual presentation, diagnosis and treatment of the tarsal tunnel syndrome was significantly delayed. To help understand the coexistence of these conditions, interrelating pathophysiologic mechanisms have been postulated, including the possibility that a "double-crush" phenomenon may have contributed to the development of tarsal tunnel syndrome. Earlier diagnosis and definitive treatment of the foot pain may have been possible had these mechanisms been better understood. PMID:2983640

  12. Anterior Tarsal Tunnel Syndrome: Electrophysiological and Clinical Evaluation of Five Cases

    Yaprak SEÇİL; Figen TOKUÇOĞLU; Yeşim BECKMANN; Şehnaz ARICI; Gaye ERYAŞAR

    2012-01-01

    Anterior tarsal tunnel syndrome is entrapment of deep peroneal nerve between the inferior extensor retinaculum and fascia overlying the talus and navicular bones that is an infrequent and probabaly overlooked condition. We report five cases which were referred to EMG laboratory with different diagnosis other than anterior tarsal tunnel syndrome. In our cases, ground sitting habits such as legs crossed position and practising “namaz” is thought to be etiological factors. As our opinion, hand d...

  13. [Anatomical variants of the medial calcaneal nerve and the Baxter nerve in the tarsal tunnel].

    Martín-Oliva, X; Elgueta-Grillo, J; Veliz-Ayta, P; Orosco-Villaseñor, S; Elgueta-Grillo, M; Viladot-Perice, R

    2013-01-01

    The tarsal tunnel is composed of the posterior border of the medial malleoulus, the posterior aspect of the talus and the medial aspect of the calcaneus. The medial calcaneal nerve emerges from the posterior aspect of the posterior tibial nerve in 75% of cases and from the lateral plantar nerve in the remaining 25%. Finally, the medial calcaneal nerve ends as a single terminal branch in 79% of cases and in numerous terminal branches in the remaining 21%. To describe the anatomical variants of the posterior tibial nerve and its terminal branches. To describe the steps for tarsal tunnel release. To describe Baxter nerve release. The anatomical variants of the posterior tibial nerve and its terminal branches within the tarsal tunnel were studied. Then the Lam technique was performed; it consists of: 1) opening of the laciniate ligament, 2) opening of the fascia over the abductor hallucis muscle, 3) exoneurolysis of the posterior tibial nerve and its terminal branches, identifying the emergence and pathway of the medial calcaneal branch, the lateral plantar nerve and its Baxter nerve branch and the medial plantar nerve. Baxter nerve was found in 100% of cases. In 100% of cases in our series the nerve going to the abductor digiti minimi muscle of the foot was found; 87.5% of cases had two terminal branches. The dissections proved that a crucial step was the release of the distal tarsal tunnel. PMID:24701749

  14. Tarsal Tunnel Syndrome Secondary to an Unreported Ossicle of the Talus: A Case Report.

    Sweed, Tamer Ahmed; Ali, Seyed Asghar; Choudhary, Surabhi

    2016-01-01

    Tarsal tunnel syndrome (TTS) is a compression neuropathy of the posterior tibial nerve in the tarsal tunnel. In about 80% of patients, a specific cause can be identified for TTS. We present a case of TTS secondary to an ossicle in close relation to the talus that, to our knowledge, has not previously been reported. A 26-year-old male presented with left ankle and foot pain that increased with activity and playing football. He had a tingling sensation and paresthesia in the sole and medial border of the foot along the distribution of the medial and lateral plantar nerves. Clinically, he had hard swelling at the floor of the tarsal tunnel, and Tinel's sign was positive. Computed tomography showed an accessory ossicle articulating with the posteromedial aspect of the talus, separating the flexor digitorum longus and flexor hallucis longus tendons, with tenosynovitis of the tibialis posterior, flexor digitorum longus and flexor hallucis longus tendons. Surgical release of the tarsal tunnel and excision of the ossicle were performed. Postoperatively, the patient showed dramatic improvement and had no complications or recurrence of symptoms after 8 months of follow-up. More interestingly, to the best of our knowledge, this ossicle has not been previously reported to cause TTS. PMID:25441278

  15. Value of computed tomography arthrography with delayed acquisitions in the work-up of ganglion cysts of the tarsal tunnel: report of three cases

    Omoumi, Patrick [Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Department of Medical Imaging, Avenue Hippocrate 10/2942, 1200, Brussels (Belgium); Centre Hospitalier Universitaire de Tours, Department of Medical Imaging, Tours (France); Gheldere, Antoine de; Leemrijse, Thibaut [Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Department of Orthopedics, Brussels (Belgium); Galant, Christine [Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Department of Pathology, Brussels (Belgium); Van den Bergh, Peter [Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Department of Neurology, Brussels (Belgium); Malghem, Jacques; Simoni, Paolo; Berg, Bruno C.V.; Lecouvet, Frederic E. [Cliniques Universitaires Saint-Luc, Universite Catholique de Louvain, Department of Medical Imaging, Avenue Hippocrate 10/2942, 1200, Brussels (Belgium)

    2010-04-15

    Ganglion cysts are a common cause of tarsal tunnel syndrome. As in other locations, these cysts are believed to communicate with neighboring joints. The positive diagnosis and preoperative work-up of these cysts require identification and location of the cyst pedicles so that they may be excised and the risk of recurrence decreased. This can be challenging with ultrasonography and magnetic resonance (MR) imaging. We present three cases of symptomatic ganglion cysts of the tarsal tunnel, diagnosed by MR imaging, where computed tomography (CT) arthrography with delayed acquisitions helped to confirm the diagnosis and identify precisely the topography of the communication with the subtalar joint. These cases provide new evidence of the articular origin of ganglion cysts developing in the tarsal tunnel. (orig.)

  16. Value of computed tomography arthrography with delayed acquisitions in the work-up of ganglion cysts of the tarsal tunnel: report of three cases

    Ganglion cysts are a common cause of tarsal tunnel syndrome. As in other locations, these cysts are believed to communicate with neighboring joints. The positive diagnosis and preoperative work-up of these cysts require identification and location of the cyst pedicles so that they may be excised and the risk of recurrence decreased. This can be challenging with ultrasonography and magnetic resonance (MR) imaging. We present three cases of symptomatic ganglion cysts of the tarsal tunnel, diagnosed by MR imaging, where computed tomography (CT) arthrography with delayed acquisitions helped to confirm the diagnosis and identify precisely the topography of the communication with the subtalar joint. These cases provide new evidence of the articular origin of ganglion cysts developing in the tarsal tunnel. (orig.)

  17. Tarsal Coalition

    ... bones in the back of the foot (the tarsal bones). This abnormal connection, which can be composed of ... and pain in one or both feet. The tarsal bones include the calcaneus (heel bone), talus, navicular, cuboid, ...

  18. Heterotopic Ossification and Entrapment of the Tibial Nerve Within the Tarsal Tunnel: A Case Report.

    Willis, Alexander R; Samad, Adil A; Prado, Gail T; Gabisan, Glenn G

    2016-01-01

    Heterotopic ossification has been reported to occur after musculoskeletal trauma (including orthopedic procedures). This has been known to cause nerve entrapment syndromes and persistent pain, limiting joint mobility. We present a case of a 19-year old female collegiate athlete who had previously undergone ankle arthroscopy and arthrotomy to remove 2 ossicles. At approximately 1 year postoperatively, the patient developed pain when planting and pivoting her foot. Imaging revealed a radiodense lesion at the posteromedial ankle consistent with heterotopic ossification and entrapment of the tibial nerve within the tarsal tunnel. The patient underwent surgical resection and postoperative indomethacin prophylaxis. At the 1-year follow-up visit, the patient remained asymptomatic, without evidence of recurrence of the heterotopic ossification. In our review of the published data, we found no previously reported cases of heterotopic ossification causing entrapment of the tibial nerve within the tarsal tunnel. In the present case report, we describe this rare case and the postulated etiologies and pathophysiology of this disease process. In addition, we discuss the clinical signs and symptoms and recommended imaging modalities and treatment. PMID:27079305

  19. Tarsal bone disintegration in leprosy

    Tarsal bone disintegration is characterised by fragmentation and progressive collapse of one or more tarsal bones. It occurs in 10% of leprosy patients, and is responsible for many severe foot deformities associated with this disease. The main cause is micro-traumata, but sensory impairment, sepsis and osteoporosis are predisposing factors. In this series of 400 consecutive patients the talus and navicular were involved most frequently (72% of 119 tarsal lesions). Treatment, including prolonged immobilisation of the foot, results in dense sclerosis of the affected bone, and leaves a functional limb. Initial radiological features include bone fragmentation, calcified fragments in adjacent soft tissues, linear fractures, progressive compression and deformity of the affected bone, loss of density of the affected bone and flattening of the longitudinal plantar arch. Illustrative case histories are presented, and the differential diagnosis discussed. (author)

  20. Bone scintigraphy as an aid in the diagnosis of occult distal tarsal bone trauma in three horses

    History, physical examination, and bone scintigraphy were used to diagnose central and/or third tarsal bone trauma in 3 acutely lame horses. In all 3 cases, the results of initial radiographic examination were negative. Bone scintigraphy revealed focal, intense radioisotope uptake at the level of the distal tarsal bones in the 3 horses. Radiographs obtained 4 weeks after injury in one horse demonstrated a slab fracture of the central tarsal bone. Conservative management of the tarsal bone disease resulted in acceptable return to function in all 3 horses

  1. Imaging findings of tarsal chondroblastoma

    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. (authors)

  2. Tarsal Coalitions--Calcaneonavicular Coalitions.

    Swensen, Stephanie J; Otsuka, Norman Y

    2015-12-01

    Calcaneonavicular coalitions are an important cause of adolescent foot pain and deformity. The congenital condition is characterized by an aberrant osseous, cartilaginous, or fibrinous union of the calcaneal and navicular bones. Calcaneonavicular coalitions are the most common form of tarsal coalitions identified within epidemiologic studies. A thorough understanding of this clinically significant entity is important for restoring joint motion and preventing long-term disability. PMID:26589085

  3. Cancellous structure of tarsal bones.

    D N Sinha

    1985-01-01

    The internal structure of the tarsal bones has been studied to investigate their cancellous architecture. It is revealed that these bones have fine and coarse meshworks and even a tendency for obliteration of the trabecular pattern in the bones lying distal to this midtarsal joint. Internal structure of the talus does not show an arched pattern of bony lamellae. An increased density of bony lamellae in the internal structure of the navicular bone could result from excessive stress, enforced b...

  4. CUBOID-NAVICULAR TARSAL COALITION

    Prado, Marcelo Pires; Mendes, Alberto Abussamara Moreira; Olivi, Rogério; Amodio, Daniel Tassetto

    2015-01-01

    The authors present the case of a nine-year-old female patient who presented with pain in her right foot associated with physical activities. After this case was diagnosed as cuboid-navicular tarsal coalition, the patient was treated surgically with resection of the coalition, thereby resolving the symptoms. The literature was reviewed and the importance of adequate physical examination and imaging assessment for investigating foot pain in children and adolescents was discussed. PMID:27047815

  5. Tarsal navicular stress fractures: radiographic evaluation

    Pavlov, H.; Torg, J.S.; Freiberger, R.H.

    1983-09-01

    Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.

  6. Tarsal navicular stress fractures: radiographic evaluation

    Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated

  7. Rhinosporidiosis of the tarsal conjunctiva

    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.

  8. The adult tarsal navicular: why it matters

    The adult tarsal navicular is an integral part of the midfoot. Many unique pathological conditions affect its function, and while subtle in their presentation, they can be significant sources of pain and deformity. Recognition of these abnormalities in imaging is essential to obtaining prompt diagnoses and instigating early management interventions. In this pictorial essay, accessory ossicles, stress fractures, avascular necrosis, and tarsal coalitions involving the navicular will be discussed in terms of their characteristic imaging findings. Normal anatomy and biomechanical functional aspects of the navicular will be reviewed and multiple images from plain film, ultrasound, bone scan, computed tomography, and magnetic resonance imaging will be presented. Improved familiarity with the adult tarsal navicular and its various abnormalities will enable radiologists to recognize its importance in the differential diagnosis of midfoot pathology. (author)

  9. The adult tarsal navicular: why it matters

    Scott-Moncrieff, A. [Univ. of British Columbia, Vancouver, British Columbia (Canada)], E-mail: ascottmo@interchange.ubc.ca; Forster, B.B.; Andrews, G. [Dept. of Radiology, Univ. of British Columbia Hospital, Vancouver, British Columbia (Canada); Khan, K. [Dept. of Family Practice, Univ. of British Columbia Hospital, Vancouver, British Columbia (Canada); Allan McGavin Sports Medicine Clinic, Vancouver, British Columbia (Canada)

    2007-12-15

    The adult tarsal navicular is an integral part of the midfoot. Many unique pathological conditions affect its function, and while subtle in their presentation, they can be significant sources of pain and deformity. Recognition of these abnormalities in imaging is essential to obtaining prompt diagnoses and instigating early management interventions. In this pictorial essay, accessory ossicles, stress fractures, avascular necrosis, and tarsal coalitions involving the navicular will be discussed in terms of their characteristic imaging findings. Normal anatomy and biomechanical functional aspects of the navicular will be reviewed and multiple images from plain film, ultrasound, bone scan, computed tomography, and magnetic resonance imaging will be presented. Improved familiarity with the adult tarsal navicular and its various abnormalities will enable radiologists to recognize its importance in the differential diagnosis of midfoot pathology. (author)

  10. Giant epidermal cyst of the tarsal plate

    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.

  11. Tarsal coalitions: CT and MRI findings

    Objective: Tarsal coalition is a rare congenital disorder which represents the abnormal fusion of two or more tarsal bones. The purpose of this paper is to describe our experience with CT and MR in this articular disorder, helping to improve its diagnosis, which in many cases is missed. It is most often diagnosed when the tarsal region is examined for other reasons, than as a confirmation of a preliminary clinical diagnosis. Material and Method: Between January 1999 and May 2001, we studied 16 cases of tarsal coalitions, with CT and/or MR. A helical Toshiba K-press tomograph, a conventional TC 60-X tomograph (performing reconstruction algorithms with bone filter, and 2 mm sections per 2 mm of bed displacement) and a 1.5 Tessla Toshiba Visart MR equipment (axial, sagittal and coronal planes, with T1, T2-weighted, and T2 with fat suppression sequences) were used. Results: In the 16 cases evaluated, 28 tarsal coalitions were detected. Eight patients had bilateral coalitions (50%) and of the 8 remaining patients with unilateral disorders, 4 had 4 coexistent coalitions (25%). Eight bony bars were detected (28.5%) and 20 were non-ossified-cartilaginous and/or fibrous- (71.5%); 14 of them (50%) were talo-calcaneal, 8 (28.5%) were calcaneo-navicular, 4 (14.2%) were talo-navicular and 2 (7.1%) were cuboid-navicular coalitions. Conclusion: Calcaneo-navicular and talo-calcaneal coalitions account for approximately 80% of all cases. Conventional radiology is usually the initial method to study these lesions and often allows to make the diagnosis without the need for more complex methods. When the radiological findings are non-existent or misleading, CT or MRI may lead to a final diagnosis: to differentiate among the various subtypes and to assess the degree of articular involvement, which is mandatory in order to define the appropriate treatment. (author)

  12. Subclinical Carpal Tunnel Syndrome in Patients with Acute Stroke

    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.

  13. Peculiar chondroblastoma involving multiple tarsal bones

    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.)

  14. Peculiar chondroblastoma involving multiple tarsal bones

    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.)

  15. Fractures and Dislocations of the Tarsal Navicular.

    Ramadorai, Maj Uma E; Beuchel, Matthew W; Sangeorzan, Bruce J

    2016-06-01

    Fractures of the tarsal navicular are commonly the result of trauma or chronic overload. Because of its complex anatomy and blood supply, the tarsal navicular is susceptible to osteonecrosis, and injury to this bone can lead to posttraumatic arthrosis of the surrounding joints. Diagnosis of the injury, especially in patients with stress fractures, can require a high index of suspicion and the use of advanced imaging. The treatment of stress fracture is controversial and ranges from immobilization in a non-weight-bearing cast or boot to internal fixation with or without bone grafting. Traumatic fractures are treated with open reduction and internal fixation with or without external fixation for medial and lateral column stabilization. To avoid a poor outcome, concomitant injuries must be recognized and treated. Despite appropriate treatment, patients may ultimately require fusion procedures to address ongoing pain and disability. PMID:27213621

  16. Central tarsal bone fracture in the border collie.

    Guilliard, M

    2007-07-01

    Fracture of the plantar process of the central tarsal bone together with a dorsomedial displacement of the body of the bone was seen in six border collies. All injuries occurred during free exercise, with no extrinsic trauma. Three dogs had concomitant tarsal fractures. Primary treatment was by lag screwing the central tarsal bone to the fourth tarsal bone. All cases eventually made an excellent recovery. The superficial radiographic appearance was of a luxation of the bone as reported in a previous series, but appraisal of the radiographs showed evidence of fracture in all cases. A cadaver study to assess the mechanism of luxation showed that it is unlikely to occur naturally. PMID:17490445

  17. Kohler’s Disease Secondary to Tarsal Pyogenic Arthritis

    Alfredo Tagarro; Julia Yebra; Martina Steiner; Nuria Bonsfills; José Carmelo Albillos; Aida Sánchez; Lorena Cid; Alfonso Cañete

    2011-01-01

    Kohler’s disease is an osteochondrosis of the tarsal navicular bone. The exact causes of osteochondrosis remain unknown. We report a 4-year-old girl with a haematogenous tarsal arthritis who developed a Köhler’s disease immediately after the infection. It is hypothesised that avascular necrosis of the navicular bone was developed secondary to pyogenic arthritis.

  18. Hansen′s disease with bilateral tarsal disorganisation

    Nair Pradeep; Vijayadharan M; Yogirajan K; Suprakasan S; Rajasree P

    1999-01-01

    A 37-year old male patient with Hansen′s disease midborderline spectrum, presented with bilateral pedal edema. X-ray examination of the feet showed disorganisation and disintegration of the tarsal bones. Bilateral tarsal disorganisation which can develop in Hansen′s disease is usually not recognised by the clinician.

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

    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. Isolated dorsal dislocation of the tarsal naviculum.

    Hamdi, Kaziz; Hazem, Ben Ghozlen; Yadh, Zitoun; Faouzi, Abid

    2015-01-01

    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. PMID:26806978

  1. Isolated dorsal dislocation of the tarsal naviculum

    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.

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

    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.

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

    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

  4. Intradermal Therapy (Mesotherapy) for the Treatment of Acute Pain in Carpal Tunnel Syndrome: A Preliminary Study

    Conforti, Giorgio; Capone, Loredana; Corra, Stefano

    2013-01-01

    Background The carpal tunnel syndrome (CTS) is the most common cause of severe hand pain. In this study we treated acute pain in CTS patients by means of local intradermal injections of anti-inflammatory drugs (mesotherapy). Methods In twenty-five patients (forty-five hands), CTS diagnosis was confirmed by clinical and neurophysiological examination prior to mesotherapy. A mixture containing lidocaine 10 mg, ketoprophen lysine-acetylsalycilate 80 mg, xantinol nicotinate 100 mg, cyanocobalamin...

  5. Form and function in the hominoid tarsal skeleton.

    Harcourt-Smith, W. E. H.

    2003-01-01

    This thesis explores form variation in the adult tarsal skeleton of extant and fossil hominoids. Three dimensional coordinate data were obtained from five bones of the foot: the calcaneus, talus, cuboid, navicular and medial cuneiform. The comparative sample was made up of Homo sapiens, Pan troglodytes troglodytes, Pan paniscus, Gorilla gorilla gorilla and Pongo pygmaeus. The fossil sample consisted of tarsal remains assigned to a number of Late Pliocene taxa: Australopithecus ...

  6. The Congenital Radiouinar Synostcsis by a Rare Tarsal Callition

    Cever, Ilhan; Guney, Nejat; Kir, Nail; Numan, Sinasi

    2004-01-01

    A Congenital pes plano-valgus case which is caused by o rare tarsal coalition. In this article, bilateral congenital tarsal coalition have been reported which is composed by bony fusion between the talus and the navicular and between the calcaneus, the cuboid and the lateral cuneiform. Triple artrodesis operation has been done in this case which has excessive pes plano-valgus deforinity together with severe pain.

  7. Coalizão tarsal cuboide-navicular Cuboid-navicular tarsal coalition

    Marcelo Pires Prado; Alberto Abussamara Moreira Mendes; Rogério Olivi; Daniel Tassetto Amodio

    2010-01-01

    Os autores apresentam caso de paciente do sexo feminino de nove anos de idade que apresentava dores no pé direito associadas à prática de atividades físicas. Após o diagnóstico de coalizão tarsal cuboide-navicular foi tratada cirurgicamente através de ressecção desta, com resolução dos sintomas. Realizam revisão da literatura e discutem a importância da adequada avaliação clínica e imagenológica dos casos das dores no pé nas crianças e adolescentes.The authors present a case of a 9-year-old f...

  8. Coalizão tarsal cuboide-navicular Cuboid-navicular tarsal coalition

    Marcelo Pires Prado

    2010-01-01

    Full Text Available Os autores apresentam caso de paciente do sexo feminino de nove anos de idade que apresentava dores no pé direito associadas à prática de atividades físicas. Após o diagnóstico de coalizão tarsal cuboide-navicular foi tratada cirurgicamente através de ressecção desta, com resolução dos sintomas. Realizam revisão da literatura e discutem a importância da adequada avaliação clínica e imagenológica dos casos das dores no pé nas crianças e adolescentes.The authors present a case of a 9-year-old female patient who presents with complaints of pain in her right foot associated with physical activities. After the diagnosis of an osseous cuboid navicular coalition she was treated surgically with resection of the coalition, with symptoms resolved. The literature is reviewed and the importance of adequate physical examination and image exams to investigate foot pain in children and teenagers is discussed.

  9. Trisomy 13: a rare case of congenital tarsal kink.

    Lucci, Lucia M; Fukumoto, Walter K; Alvarenga, Lênio S

    2003-09-01

    We describe the management of the eyelid anomaly associated with Patau syndrome. Trisomy 13 is the genotype of the syndrome's phenotype. The eyelid anomaly was a tarsal kink, a congenital malformation of the tarsus that causes entropion. A 2-month-old white girl presented with unilateral upper eyelid entropion and central corneal ulceration. To correct this condition, two 6-0 polyglactin sutures were passed through the gray line of the upper and lower eyelids and tied. Correction of the entropion and improvement in the corneal condition were achieved after surgery. No recurrence of the entropion or corneal ulceration was noted after 2 months of follow-up. This simple technique, which corrected the eyelid malposition, providing an excellent cosmetic result without incision of the tarsus, has been previously reported in other cases of tarsal kink but not in a patient with Patau syndrome. PMID:14506431

  10. The bipartite tarsal navicular bone: radiographic and computed tomography findings

    Shawdon, A. [Alphington Sports Medicine Clinic, Northcote, VIC (Australia); Kiss, Z.S. [Mercy Private Hospital, East Melbourne, VIC (Australia). Dept. of Radiology; Fuller, P. [Sports Medicine Centrs of Victoria, Ashwood. VIC (Australia)

    1995-05-01

    Two cases of bipartite tarsal navicular bone are presented. The radiographic and computed tomography (CT) findings of this anatomical variant are described. Correct recognition of this entity is important, both because it may be the cause of symptoms per se, and because it may be misdiagnosed as a fracture. When plain films are not diagnostic, CT scanning is helpful in distinguishing between a fracture and this variant. 6 refs., 4 figs.

  11. The bipartite tarsal navicular bone: radiographic and computed tomography findings

    Two cases of bipartite tarsal navicular bone are presented. The radiographic and computed tomography (CT) findings of this anatomical variant are described. Correct recognition of this entity is important, both because it may be the cause of symptoms per se, and because it may be misdiagnosed as a fracture. When plain films are not diagnostic, CT scanning is helpful in distinguishing between a fracture and this variant. 6 refs., 4 figs

  12. A Study of Ossification of Carpal and Tarsal Bones in Normal and Hypothyroid Foals

    McLaughlin, B. G.; Doige, C E

    1982-01-01

    The degree of ossification of carpal and tarsal bones was determined in normal foals of various ages and in hypothyroid and thyroidectomized foals. In normal foals ossification occurred very rapidly in the last few weeks of gestation and less rapidly from birth to 33 days. The ulnar carpal bone was consistently less ossified than other carpal or tarsal bones. Foals with congenital hyperplastic goitre had retarded ossification of the cuboidal bones, especially the central and third tarsal bone...

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

    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.

  14. Ganglia of the tarsal sinus: MR imaging features and clinical findings

    Purpose: To analyze MR imaging and clinical findings associated with ganglia of the tarsal sinus. Materials and methods: In a record search, ganglia of the tarsal sinus were retrospectively identified in 26 patients (mean age 48 ± 16 years), who underwent MR imaging for chronic ankle pain. Images were reviewed by two radiologists in consensus for size and location of ganglia, lesions of ligaments of the ankle and the tarsal sinus, tendon abnormalities, osteoarthritis, osseous erosions and bone marrow abnormalities. Medical records were reviewed for patient history and clinical findings. Results: Ganglia were associated with the interosseus ligament in 81%, the cervical ligament in 31% and the retinacula in 46% of cases. Signal alterations suggesting degeneration were found in 85%, 50% and 63% in case of the interosseus ligament, the cervical ligament and the retinacula, respectively. Scarring of the anterior talofibular ligament and the fibulocalcaneal ligament was found in 68% and 72% of the patients, respectively, while only 27% of the patients recalled ankle sprains. Ganglia at the retinacula were highly associated with synovitis and tendinosis of the posterior tibial tendon (p < 0.05). Conclusion: All patients with ganglia in the tarsal sinus presented with another pathology at the ankle, suggesting that degeneration of the tarsal sinus may be a secondary phenomenon, due to pathologic biomechanics at another site of the hind foot. Thus, in patients with degenerative changes of the tarsal sinus, one should be alerted and search for underlying pathology, which may be injury of the lateral collateral ligaments in up to 70%.

  15. Three-dimensional kinematics of the tarsal joint at the trot.

    Lanovaz, J L; Khumsap, S; Clayton, H M; Stick, J A; Brown, J

    2002-09-01

    The tarsal joint is a common site of injury for many sport horses. Understanding the biomechanics of this complex joint begins with developing a clear picture of the kinematics during normal locomotion. This study describes the 3D kinematics of the tarsal joint by measuring the motion of the tibia and third metatarsus in 4 sound Quarter Horses with targets attached directly to the bones via steel pins. The objective was to determine if the tarsus had significant motion outside the tarsocrural joint. Two Steinmann pins were inserted into the lateral side of the right hindlimb and marker triads were fixed to the end of each pin. 3D motion of the bones was recorded as each subject trotted in hand. Three rotations were expressed using an attitude vector based on the finite helical angle method. Three translations were calculated as the motion of the tibia relative to the third metatarsus. Angular and translation data were mostly coupled with flexion angle. Internal/external rotation during stance and translations during swing showed evidence of noncoupled motion. Although the majority of tarsal motion occurs in the tarsocrural joint, there is evidence that translations and rotations occur in other locations within the tarsal joint and that some of these are related to the tarsal joint 'snapping' phenomenon. This research provides a set of reference 3D kinematics which will aid in the study of the aetiology and mechanical effects of tarsal joint lameness. PMID:12405706

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

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

    2014-01-01

    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...

  17. Incomplete ossification of the tarsal bones in foals: 22 cases (1988-1996)

    To determine outcome for foals with incomplete ossification of the tarsal bones and to determine whether clinical and radiographic abnormalities at the time of initial examination were associated with outcome. Retrospective study. 22 foals. Information on signalment, history, owner's initial complaint, clinical findings, whether tarsus valgus was evident, and radiographic abnormalities was obtained from medical records. Radiographic lesions were classified as type I (i.e., incomplete ossification with 30% collapse and pinching or fragmentation of the affected bones). Follow-up information was obtained via telephone conversations with owners. Foals were between 1 day and 10 months old when first examined. Eleven were premature (i.e., < 320 days of gestation) or were twins. Sixteen had tarsus valgus. Severity of radiographic lesions was associated with outcome; 4 of 6 foals with type-I incomplete ossification of the tarsal bones performed as intended, but only 3 of 16 foals with type-II incomplete ossification of the tarsal bones performed as intended. For foals with incomplete ossification of the tarsal bones, severity of the radiographic lesions was associated with outcome. Foals with type-II incomplete ossification of the tarsal bones have a guarded prognosis for athletic soundness

  18. Stress avulsion fracture of the tarsal navicular. An uncommon sports-related overuse injury.

    Orava, S; Karpakka, J; Hulkko, A; Takala, T

    1991-01-01

    We report nine cases of stress-related avulsion fracture of the tarsal navicular in athletes. This uncommon over-use injury is thought to occur following repetitive cyclic compressive loading secondary to an impingement of the tarsal navicular. The small dorsal triangular fragment is best seen in weightbearing lateral view radiographs and isotope scan and/or tomography help confirm the diagnosis. We feel that operative treatment is the method of choice in highly symptomatic cases and among top athletes because of the shorter recovery time. PMID:1897656

  19. Irradiated homologous tarsal plate banking: a new alternative in eyelid reconstruction. Part II. Human data

    Reconstruction of full thickness eyelid defects requires the correction of both posterior lamella (tarsus, conjunctiva) and anterior lamella (skin, muscle). Irradiated homologous tarsal plate provides a structured framework for the lid reconstruction, and is incorporated nicely into the normal lid anatomy

  20. Sex estimation from the tarsal bones in a Portuguese sample: a machine learning approach.

    Navega, David; Vicente, Ricardo; Vieira, Duarte N; Ross, Ann H; Cunha, Eugénia

    2015-05-01

    Sex estimation is extremely important in the analysis of human remains as many of the subsequent biological parameters are sex specific (e.g., age at death, stature, and ancestry). When dealing with incomplete or fragmented remains, metric analysis of the tarsal bones of the feet has proven valuable. In this study, the utility of 18 width, length, and height tarsal measurements were assessed for sex-related variation in a Portuguese sample. A total of 300 males and females from the Coimbra Identified Skeletal Collection were used to develop sex prediction models based on statistical and machine learning algorithm such as discriminant function analysis, logistic regression, classification trees, and artificial neural networks. All models were evaluated using 10-fold cross-validation and an independent test sample composed of 60 males and females from the Identified Skeletal Collection of the 21st Century. Results showed that tarsal bone sex-related variation can be easily captured with a high degree of repeatability. A simple tree-based multivariate algorithm involving measurements from the calcaneus, talus, first and third cuneiforms, and cuboid resulted in 88.3% correct sex estimation both on training and independent test sets. Traditional statistical classifiers such as the discriminant function analysis were outperformed by machine learning techniques. Results obtained show that machine learning algorithm are an important tool the forensic practitioners should consider when developing new standards for sex estimation. PMID:25186617

  1. The value of spiral CT scan on fracture of ankle joint and tarsal bones

    Objective: To study the value of spiral CT scan on the fracture of ankle joint and tarsal bones. Methods: 43 cases with the fracture of ankle joint and tarsal bones were collected and analyzed. All the cases were examined by plain film radiography and spiral CT thin slice scan. Multi-planar reformation (MPR), surface shaded display (SSD) and other techniques of image post-processing were performed in 35 cases of them. Results: Spiral CT scan could demonstrate more fractures than plain film radiography in 28 cases(65.1%). There are 15 cases (34.9%) which are normal in plain film radiography but abnormal in Spiral CT scan. Spiral CT could demonstrate the different length, width, direction and number of linear low density shadow. SSD and MPR were performed again in the cases with avulsion fracture and fragmental fracture to demonstrate the fracture direction and the shape, size and location of fragments more clearly. Conclusion: Spiral CT thin slice scan with image post-processing techniques can play an important role in fracture of ankle joint and tarsal bones. (authors)

  2. Acute cerebellitis successfully managed with temporary cerebrospinal fluid diversion using a long tunnel external ventricular drain: a long-term radiological follow-up of two cases.

    Waqas, Muhammad; Hadi, Yousaf Bashir; Sheikh, Sadaf; Shamim, Shahzad M

    2016-01-01

    Acute cerebellitis (AC) is a rare inflammatory childhood disorder. Although there is no consensus on standard treatment for cerebellitis, its outcome is usually favourable. We report two cases of AC in the paediatric age group, successfully managed with long tunnel external ventricular drain (EVD). The first patient was an 8-year-old boy with a history of fever and headache. Sequential MRI showed diffuse cerebellar swelling with tonsillar herniation and resulting hydrocephalus. The second patient was a 6-month-old boy who presented with high-grade fever associated with chills. CT scan of the head showed triventricular hydrocephalus with obliteration of cerebrospinal fluid spaces and cisterns. Both patients underwent immediate emergency right-sided long tunnel EVD insertion. The EVD was removed on the 9th day in the first patient and the 10th day in the second patient; the patients showed no neurological deficits at a follow-up of 2 years and 1 year, respectively. PMID:27166004

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

    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.

  4. Pronounced variation in tarsal and foot feathering in the upland buzzard (Buteo hemilasius) in Mongolia

    Ellis, D.H.; Woffinden, N.; Whitlock, P.L.; Tsengeg, P.

    1999-01-01

    During 1994, 1995, 1997, and 1998 expeditions across Mongolia, we located over 250 upland buzzard (Buteo hemilasius) nests. At these, we noted considerable morphological variation in plumage coloration and in leg pterylosis. In 1997 and 1998, we examined 131 nests scattered across eastern and central Mongolia and report here the tarsal condition of 119 nestlings from 59 broods where young were at least 2 weeks of age. Of 119 birds carefully examined, 50 (42%) had less than fully feathered tarsi and 4 of the 69 with fully feathered tarsi had scattered feathers on their toes. Thus, 54 of 119 birds (45%) in some way deviated from the feathered tarsibare toes condition. This extraordinary degree of variability in feather patterns may be best explained as the result of extensive and relatively recent hybridization between the longlegged (Buteo rufinus) and roughlegged (B. lagopus) buzzards and/or between long-legged and upland buzzards.

  5. Primate tarsal bones from Egerkingen, Switzerland, attributable to the middle Eocene adapiform Caenopithecus lemuroides

    Erik R. Seiffert

    2015-06-01

    Full Text Available The middle Eocene species Caenopithecus lemuroides, known solely from the Egerkingen fissure fillings in Switzerland, was the first Paleogene fossil primate to be correctly identified as such (by Ludwig Rütimeyer in 1862, but has long been represented only by fragmentary mandibular and maxillary remains. More recent discoveries of adapiform fossils in other parts of the world have revealed Caenopithecus to be a biogeographic enigma, as it is potentially more closely related to Eocene adapiforms from Africa, Asia, and North America than it is to any known European forms. More anatomical evidence is needed, however, to provide robust tests of such phylogenetic hypotheses. Here we describe and analyze the first postcranial remains that can be attributed to C. lemuroides—an astragalus and three calcanei held in the collections of the Naturhistorisches Museum Basel that were likely recovered from Egerkingen over a century ago. Qualitative and multivariate morphometric analyses of these elements suggest that C. lemuroides was even more loris-like than European adapines such as Adapis and Leptadapis, and was not simply an adapine with an aberrant dentition. The astragalus of Caenopithecus is similar to that of younger Afradapis from the late Eocene of Egypt, and parsimony and Bayesian phylogenetic analyses that include the new tarsal data strongly support the placement of Afradapis and Caenopithecus as sister taxa to the exclusion of all other known adapiforms, thus implying that dispersal between Europe and Africa occurred during the middle Eocene. The new tarsal evidence, combined with previously known craniodental fossils, allows us to reconstruct C. lemuroides as having been an arboreal and highly folivorous 1.5–2.5 kg primate that likely moved slowly and deliberately with little or no capacity for acrobatic leaping, presumably maintaining consistent powerful grasps on branches in both above-branch and inverted postures.

  6. Ball and socket ankle joint in connection with bilateral tarsal synostosis in a boy with congenital absence of the portal vain: a novel malformation complex

    Zandieh, Shahin; Vakli-Adli, Anosheh; Hochreiter, Josef; Grill, Franz; Klaushofer, Klaus; Al Kaissi, Ali

    2008-01-01

    Background Contracted valgus flat foot in the adolescent is frequently caused by tarsal synostosis or synchondrosis. These synostoses are prevalently symptomatic during adolescence, when by ossifying they block the subtalar joint in valgus. Careful and detailed examinations might reveal additional abnormalities. Case presentation A 16-year-old boy of Austrian origin presented with contracted valgus foot associated with tarsal hypomobility and pain. Talonavicular synostosis with ball and socke...

  7. Irradiated homologous tarsal plate banking: A new alternative in eyelid reconstruction. Part I. Technique and animal research

    Reconstruction of full thickness eyelid defects requires the correction of both posterior lamella (tarsus, conjunctiva) and anterior lamella (skin, muscle). Tarsal substitutes including banked sclera, nasal cartilage, ear cartilage, and periosteum can be beneficial for posterior lamellar repair, while anterior lamellar replacement, including skin grafts, pedicle flaps, advancement flaps, etc., is important to cover the posterior reconstructed portion. At times, due to extensive tissue loss, the eyelid reconstruction can be particularly challenging. We have found an alternative posterior lamellar reconstructive technique utilizing irradiated homologous tarsal plate that can be particularly useful in selected cases of severe tissue loss. The experimental surgical procedure in monkeys and the histological fate of the implanted tarsus is described in Part I, and followed in Part II by our experience with this tissue in six human patients

  8. Tarsal navicular relations in club foot: is there a role for magnetic resonance imaging?

    O`Connor, P.J. [Department of Radiology, CT/MRl Unit, The General Infirmary at Leeds (United Kingdom)]|[Department of Clinical Radiology, Leiden University Hospital, Albinusdreef 2, 2333 AA Leiden (Netherlands); Bos, C.F.A. [Department of Orthopedic Surgery, Leiden University Hospital, Albinusdreef 2, 2333 AA Leiden (Netherlands); Bloem, J.L. [Department of Clinical Radiology, Leiden University Hospital, Albinusdreef 2, 2333 AA Leiden (Netherlands)

    1998-08-01

    Objective. To correlate radiographic and MR appearances with surgical findings to determine the accuracy of these modalities in demonstrating tarsal navicular (TN) relations in order to select the appropriate surgical intervention. Design and patients. Fourteen consecutive patients with 19 club feet had anteroposterior and lateral radiographs and magnetic resonance (MR) imaging performed. Blinded retrospective interpretation of these studies was correlated with surgical findings. Movement artifact was responsible for initial non-diagnostic MR scans in 3 out of 19 feet. Results. Plain radiographs and MR imaging had sensitivities of 79% and 84% respectively for TN subluxation, while both modalities had 100% positive predictive value for TN subluxation. Each modality produced indeterminate results in cases where subluxation was present at surgery, but in combination there were no false negatives. Conclusion. Radiography confidently predicted the TN alignment in the majority of cases. MR demonstrated TN relationships in all cases where radiography was indeterminate. It is proposed that MR has a potential role to demonstrate TN relationships when radiography is indeterminate or when there is disparity between the clinical and radiographic assessment. (orig.) With 5 figs., 12 refs.

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

    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.

  10. Tarsal navicular relations in club foot: is there a role for magnetic resonance imaging?

    Objective. To correlate radiographic and MR appearances with surgical findings to determine the accuracy of these modalities in demonstrating tarsal navicular (TN) relations in order to select the appropriate surgical intervention. Design and patients. Fourteen consecutive patients with 19 club feet had anteroposterior and lateral radiographs and magnetic resonance (MR) imaging performed. Blinded retrospective interpretation of these studies was correlated with surgical findings. Movement artifact was responsible for initial non-diagnostic MR scans in 3 out of 19 feet. Results. Plain radiographs and MR imaging had sensitivities of 79% and 84% respectively for TN subluxation, while both modalities had 100% positive predictive value for TN subluxation. Each modality produced indeterminate results in cases where subluxation was present at surgery, but in combination there were no false negatives. Conclusion. Radiography confidently predicted the TN alignment in the majority of cases. MR demonstrated TN relationships in all cases where radiography was indeterminate. It is proposed that MR has a potential role to demonstrate TN relationships when radiography is indeterminate or when there is disparity between the clinical and radiographic assessment. (orig.)

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

    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. PMID:25704449

  12. Semisimple tunnels

    Cho, Sangbum

    2010-01-01

    A knot in the 3-sphere in (1,1)-position (that is, in 1-bridge position with respect to a Heegaard torus) can be described by an element of the braid group of two points in the torus. Our main results tell how to translate between a braid group element and the sequence of slope invariants of the upper tunnel (or lower tunnel) associated to the corresponding (1,1)-position. This enables us to calculate the slope invariants of the four tunnels of the (-2,3,7)-pretzel knot, and to verify previous calculations of the slope invariants for all tunnels of 2-bridge knots and (1,1)-tunnels of torus knots. We also characterize a class of (1,1)-positions that we call toroidal, in terms of the slope invariants of the associated upper tunnel. Finally, we develop a general algorithm to calculate the slope invariants of the associated tunnels, given a braid description. We have implemented the algorithm and other results as software, and we give some sample computations.

  13. Unusual Variant of the Nutcracker Fracture of the Calcaneus and Tarsal Navicular

    Gajendran, Varun K.; Yoo, Brad J.; Hunter, John C.

    2015-01-01

    A 62-year-old woman with severe seizure disorder presented with right ankle and foot pain after being found down, presumably following a seizure recurrence. Imaging showed an acute comminuted fracture of the anterolateral aspect of the right calcaneus, as well as an acute avulsion fracture of the right navicular tuberosity at the site of insertion of the tibialis posterior tendon. This fracture pattern suggests forced abduction of the midfoot or forefoot with severe compression of the lateral...

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

    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. PMID:19622233

  15. Classical Tunneling

    Cohn, A G; Rabinowitz, Mario

    2003-01-01

    A classical representation of an extended body over barriers of height greater than the energy of the incident body is shown to have many features in common with quantum tunneling as the center-of-mass literally goes through the barrier. It is even classically possible to penetrate any finite barrier with a body of arbitrarily low energy if the body is sufficiently long. A distribution of body lengths around the de Broglie wavelength leads to reasonable agreement with the quantum transmission coefficient.

  16. Classical Tunneling

    Cohn, Arthur; Rabinowitz, Mario

    2003-01-01

    A classical representation of an extended body over barriers of height greater than the energy of the incident body is shown to have many features in common with quantum tunneling as the center-of-mass literally goes through the barrier. It is even classically possible to penetrate any finite barrier with a body of arbitrarily low energy if the body is sufficiently long. A distribution of body lengths around the de Broglie wavelength leads to reasonable agreement with the quantum transmission...

  17. Soliton tunneling

    Kälbermann, G.

    1997-01-01

    We present a numerical simulation of the scattering of a topological soliton off finite size attractive impurities, repulsive impurities and a combination of both. The attractive and attractive-repulsive cases show similar features to those found for $\\delta$ function type of impurities. For the repulsive case, corresponding to a finite width barrier, the soliton behaves completely classically. No tunneling occurs for sub-barrier kinetic energies despite the extended nature of the soliton.

  18. Carpal Tunnel Surgery

    Full Text Available ... carried out for the condition of carpal tunnel syndrome. Carpal Tunnel Syndrome is a neuropathy where the median nerve gets ... of the hand. The surgery for carpal tunnel syndrome consists of a release of the transverse carpal ...

  19. Tunneling technologies for the collider ring tunnels

    The Texas site chosen for the Superconducting Super Collider has been studied, and it has been determined that proven, conventional technology and accepted engineering practice are suitable for constructing the collider tunnels. The Texas National Research Laboratory Commission report recommended that two types of tunneling machines be used for construction of the tunnels: a conventional hard rock tunnel boring machine (TBM) for the Austin chalk and a double shielded, rotary TBM for the Taylor marl. Since the tunneling machines usually set the pace for the project, efficient planning, operation, and coordination of the tunneling system components will be critical to the schedule and cost of the project. During design, tunneling rate prediction should be refined by focusing on the development of an effective tunneling system and evaluating its capacity to meet or exceed the required schedules. 8 refs., 13 figs

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

    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. PMID:27585103

  1. CLINICAL ANALYSIS OF ACUTE CARPAL TUNNEL SYNDROME AFTER REDUCTION OF Colles' FRACTURE IN TWENTY-TWO PATIENTS%Colles骨折复位后致急性腕管综合征22例临床分析

    冯仕明; 高顺红; 焦成; 陈超; 刘德群

    2011-01-01

    Objective To investigate the etiology, diagnosis, and treatment of acute carpal tunnel syndrome (ACTS) after reduction of Colles' fracture. Methods Between December 2006 and June 2010, 22 patients with ACTS after reduction of Colles' fracture were treated with expectant treatment and surgical treatment. There were 9 males and 13 females with an average age of 46.2 years (range, 23-60 years). Fractures were caused by traffic accident in 9 cases, falling in 8 cases, falling from height in 2 cases, hitting in 2 cases, and crushing in 1 case. The mechanism of fracture was direct violence in 3 cases and indirect violence in 19 cases. According to Gartland & Werley classification, there were 2 cases of type I, 5 cases of type II, 14 cases of type III, and 1 case of type IV. Closed reduction was performed in 19 cases and open reduction and internal fixation (ORIF) in 3 cases. The average symptom time of ACTS after reduction of Colles' fracture was 11.6 hours (range, 1 hour 30 minutes to 48 hours) in patients undergoing closed reduction and was 24 hours in 1 patient and 2 weeks in 2 patients undergoing ORIF. Expectant treatment was performed first, the forearms were put in neutral position in closed reduction cases; if there was no relief of ACTS symptom 1 week later, the mixture of 1 mL glucocorticosteroid and 1 mL 2% lidocaine was injected into carpal tunnel once a week for 2 weeks. The mixture was injected into carpal tunnel directly once a week for 2 weeks in ORIF cases. In the patients who failed to expectant treatments, ORIF was performed. Results In 7 cases of type III that failed expectant treatment, ACTS symptoms were relief completely after ORIF. All the 22 patients were followed up 12 months on average (range, 8-18 months). The average time of complete disappearance of median nerve compression symptom was 11 days (range, 2-25 days). All the patients had normal finger motion, sensation, and opposition of thumb with no sensation of anaesthesia and pinprick. The

  2. Transonic Dynamics Tunnel (TDT)

    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...

  3. Carpal Tunnel Surgery

    Full Text Available ... that is putting pressure on the median nerve. This is the procedure of carpal tunnel syndrome release, ... for the condition of carpal tunnel syndrome. At this point in time, we have the patient under ...

  4. Carpal tunnel syndrome

    Median nerve dysfunction; Median nerve entrapment ... Calandruccio JH. Carpal tunnel syndrome, ulnar tunnel syndrome, and stenosing tenosynovitis. In: Canale ST, Beaty JH, eds. Campbell's Operative Orthopaedics . 12th ed. Philadelphia, PA: Elsevier Mosby; 2013: ...

  5. Cubital Tunnel Syndrome

    ... Symptom Picker Hand and Arm Conditions Carpal Tunnel Ganglion Cysts Trigger Finger Arthritis Base of the Thumb See ... Symptom Picker Hand and Arm Conditions Carpal Tunnel Ganglion Cysts Trigger Finger Arthritis Base of the Thumb See ...

  6. Hypersonic Tunnel Facility (HTF)

    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,...

  7. Magnetic tunnel junctions (MTJs)

    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.

  8. Reconstruction of the Midfoot Using a Free Vascularized Fibular Graft After En Bloc Excision for Giant Cell Tumor of the Tarsal Bones: A Case Report.

    Hara, Hitomi; Kawamoto, Teruya; Onishi, Yasuo; Fujioka, Hiroyuki; Nishida, Kotaro; Kuroda, Ryosuke; Kurosaka, Masahiro; Akisue, Toshihiro

    2016-01-01

    We report the case of a 32-year-old Japanese female with a giant cell tumor of bone involving multiple midfoot bones. Giant cell tumors of bone account for approximately 5% of all primary bone tumors and most often arise at the ends of long bones. The small bones, such as those of the hands and feet, are rare sites for giant cell tumors. Giant cell tumors of the small bones tend to exhibit more aggressive clinical behavior than those of the long bones. The present patient underwent en bloc tumor excision involving multiple tarsals and metatarsals. We reconstructed the longitudinal arch of the foot with a free vascularized fibular graft. At the 2-year follow-up visit, bony union had been achieved, with no tumor recurrence. PMID:26213165

  9. Treatment of Spontaneous Osteonecrosis of the Tarsal Navicular With a Free Medial Femoral Condyle Vascularized Bone Graft: A New Approach to Managing a Difficult Problem.

    Levinson, Howard; Miller, Kyle J; Adams, Samuel B; Parekh, Selene G

    2013-12-23

    Adult-onset spontaneous osteonecrosis of the tarsal navicular joint, or Mueller-Weiss syndrome (MWS), is an uncommon debilitating disease characterized by a painful clinical course with progressive midfoot deformity. Treatment options include nonoperative management and/or operative intervention, including percutaneous decompression of the navicular bone, stabilization of existing structures, and cancellous bone grafting from the tibia or iliac crest. To our knowledge, there have been no reported cases of treatment of MWS with a vascularized bone graft. We report an unusual case of unilateral MWS in a 25-year-old male who failed nonoperative therapy and was successfully treated with a novel operative approach using debridement followed by a free medial femoral condyle vascularized bone graft. At 18-month follow-up, the patient demonstrated an excellent outcome with return to previous level of function, including work-related and recreational activities. PMID:24368773

  10. Reconstruction of large upper eyelid defects with a free tarsal plate graft and a myocutaneous pedicle flap plus a free skin graft

    Toft, Peter B

    2016-01-01

    PURPOSE: To review and present the results of a one-step method employing a free tarsal plate graft and a myocutaneous pedicle flap plus a free skin graft for reconstruction of large upper eyelid defects after tumour surgery. METHODS: This was a retrospective case-series of 8 patients who underwent...... reconstructed with a laterally based myocutaneous pedicle flap in 7 patients, leaving a raw surface under the brow which was covered with a free skin graft. In 1 patient with little skin left under the brow, the anterior lamella was reconstructed with a bi-pedicle orbicularis muscle flap together with a free...... skin graft. RESULTS: All patients healed without necrosis, did not suffer from lagophthalmos, achieved reasonable cosmesis, and did not need lubricants. In one patient, a contact lens was necessary for three weeks because of corneal erosion. One patient still needs a contact lens 3 months after...

  11. Proton tunneling in solids

    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)

  12. Middle tunnels by splitting

    Cho, Sangbum

    2011-01-01

    For a genus-1 1-bridge knot in the 3-sphere, that is, a (1,1)-knot, a middle tunnel is a tunnel that is not an upper or lower tunnel for some (1,1)-position. Most torus knots have a middle tunnel, and non-torus-knot examples were obtained by Goda, Hayashi, and Ishihara. We generalize their construction and calculate the slope invariants for the resulting middle tunnels. In particular, we obtain the slope sequence of the original example of Goda, Hayashi, and Ishihara.

  13. An unusual cause of ankle pain: fracture of a talocalcaneal coalition as a differential diagnosis in an acute ankle sprain: a case report and literature review

    Wähnert, D. (Dirk); Grüneweller, N. (Niklas); Evers, J.; Sellmeier, A.C. (Anna); M. J. Raschke; Ochman, S

    2013-01-01

    Background: The acute ankle sprain is one of the most common injuries seen in trauma departments. Ankle sprains have an incidence of about one injury per 10 000 people a day. In contrast tarsal coalition is a rare condition occurring in not more than one percent of the population. Case presentation: We present the case of a 23 year old male patient with pain and local swelling after an acute ankle sprain. Initial clinical and radiological examination showed no pathologies. Due to prolonged pa...

  14. Tunnel magnetoresistance in alumina, magnesia and composite tunnel barrier magnetic tunnel junctions

    Schebaum, Oliver; Drewello, Volker; Auge, Alexander; Reiss, Günter; Münzenberg, Markus; Schuhmann, Henning; Seibt, Michael; Thomas, Andy

    2010-01-01

    Using magnetron sputtering, we have prepared Co-Fe-B/tunnel barrier/Co-Fe-B magnetic tunnel junctions with tunnel barriers consisting of alumina, magnesia, and magnesia-alumina bilayer systems. The highest tunnel magnetoresistance ratios we found were 73% for alumina and 323% for magnesia-based tunnel junctions. Additionally, tunnel junctions with a unified layer stack were prepared for the three different barriers. In these systems, the tunnel magnetoresistance ratios at optimum annealing te...

  15. Complex tunneling dynamics

    Yang, C.-D. [Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan (China)]. E-mail: cdyang@mail.ncku.edu.tw

    2007-04-15

    Tunneling dynamics and tunneling trajectories are modeled exactly by complex-extended Hamilton-Jacobi formulation in this paper. It is found that the wave-like properties of tunneling particles, such as reflection, refraction, and transmission resonance, can be identified and explained in terms of particle's motion in complex space with the tunneling time defined as the usual sense of classical time. Following the complex trajectories determined by the complex Hamilton equations of motion, we can connect classical trajectories smoothly with tunneling trajectories using position and velocity continuity at the interface of the media, locate the particle's position at any instant, and find the time spent by a particle within the potential. A microscopic tunneling model is also developed to explain the probabilistic nature why a particle with the same incident conditions sometimes transmits the potential and sometimes is reflected from the potential.

  16. Resonance Enhanced Tunneling

    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.

  17. Microsystem Aeromechanics Wind Tunnel

    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...

  18. Tunnel modeling with BIM tools

    Saje, Samo

    2014-01-01

    Graduation thesis deals with the process of tunnel modeling with the use of BIM tools and shows the development of libraries and families for tunnels for Revit software environment. In the first part of the thesis the process of design and construction of tunnels is presented, various tunnel construction methods and typical structure of road tunnels are described with an emphasis on the new Austrian method (NATM). The tunnel design process is broken down into individual phases, while the ...

  19. 后交叉韧带重建中股骨侧"锐角效应"的相关研究及骨道技术的评价%Correlative study of femur "acute angle" in reconstruction of posterior cruciate ligament with hamstring tendons and evaluation of bone tunnel technique

    闫昌葆; 陈百成; 赵宝辉; 孙然; 刘虎; 李嘉

    2009-01-01

    [Objective]To explore the "acute angle" of femur,and evaluate the bone tunnel technique in posterior cruciate ligament reconstruction. [Method] Using the porcine flexor digilorum tendon as graft, the author reconstructed posterior cruciate ligament. The bone tunnel was established wilh the angle of 80°,90°and 100°comparison the tunnel and intercondylar fossa of femur side wall,and press sensitive film was set between the edge of tunnel and graft. The pressure between was used to represent abrasion. The bigger the pressure was, the larger the abrasion was. The difference of pressure between bone tunnel technique group and the control group was compared. [ResultJThe pressure of angle 100°was lowest(3. 55 ±0. 21 MPa). And the pressure of burnishing group(3.29 ±0.19 MPa)was lower than that of the control group(3.55 ±0.21 MPa). [Conclusion]The bone tunnel technique can reduce the femoral; "acute angle" of femur in posterior cruciate ligament reconstruction.%[目的]探讨后交叉韧带重建中股骨侧的"锐角效应"以及对骨道技术进行评价.[方法]应用猪的屈趾肌腱作为移植物重建后交叉韧带,分别建立与股骨髁间窝侧壁呈80°、90°、100°夹角的骨道,以及对骨道边缘进行打磨处理.在骨道边缘与移植物之间放置压敏片计算得压强值来表示磨损作用的大小,压强值越大表示磨损作用越大.通过比较应用骨道技术重建PCL组与对照组的压强值来说明这种减小"锐角效应"的方法是否可行.[结果]应用骨道技术重建后交叉韧带各组中移植物与股骨髁间窝侧壁夹角为100°时压强最小[(3.55±0.21)MPa],并且对骨道边缘进行打磨后压强值[(3.29±0.19)MPa]明显低于对照组[(3.55±0.21)MPa].[结论]应用骨道技术可以有效减小后交叉韧带重建中股骨侧的"锐角效应".

  20. Carpal Tunnel Surgery

    Full Text Available ... carpal tunnel syndrome. At this point in time, we have the patient under anesthesia. We have the hand prepped. Great. And then, the ... the carpal tunnel, and it’s the ligament that we incise to release the carpal canal. The carpal ...

  1. Coherent revival of tunneling

    Hsu, Liang-Yan; Rabitz, Herschel

    2015-07-01

    We introduce a tunneling effect by a driving field, referred to as coherent revival of tunneling (CRT), corresponding to complete tunneling (transmission coefficient =1 ) that is revived from the circumstance of total reflection (transmission coefficient ≈0 ) through application of an appropriate perpendicular high-frequency ac field. To illustrate CRT, we simulate electron transport through fish-bone-like quantum-dot arrays by using single-particle Green's functions along with Floquet theory, and we explore the corresponding current-field amplitude characteristics as well as current-polarization characteristics. In regard to the two characteristics, we show that CRT exhibits entirely different features than coherent destruction of tunneling and photon-assisted tunneling. We also discuss two practical conditions for experimental realization of CRT.

  2. Tunnel fire dynamics

    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.

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

    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.

  4. The aeolian wind tunnel

    Iversen, J. D.

    1991-01-01

    The aeolian wind tunnel is a special case of a larger subset of the wind tunnel family which is designed to simulate the atmospheric surface layer winds to small scale (a member of this larger subset is usually called an atmospheric boundary layer wind tunnel or environmental wind tunnel). The atmospheric boundary layer wind tunnel is designed to simulate, as closely as possible, the mean velocity and turbulence that occur naturally in the atmospheric boundary layer (defined as the lowest portion of the atmosphere, of the order of 500 m, in which the winds are most greatly affected by surface roughness and topography). The aeolian wind tunnel is used for two purposes: to simulate the physics of the saltation process and to model at small scale the erosional and depositional processes associated with topographic surface features. For purposes of studying aeolian effects on the surface of Mars and Venus as well as on Earth, the aeolian wind tunnel continues to prove to be a useful tool for estimating wind speeds necessary to move small particles on the three planets as well as to determine the effects of topography on the evolution of aeolian features such as wind streaks and dune patterns.

  5. Spin Tunneling in Conducting Oxides

    Bratkovsky, Alexander

    1997-01-01

    Direct tunneling in ferromagnetic junctions is compared with impurity-assisted, surface state assisted, and inelastic contributions to a tunneling magnetoresistance (TMR). Theoretically calculated direct tunneling in iron group systems leads to about a 30% change in resistance, which is close to experimentally observed values. It is shown that the larger observed values of the TMR might be a result of tunneling involving surface polarized states. We find that tunneling via resonant defect sta...

  6. Carpal Tunnel Surgery

    Full Text Available ... of carpal tunnel syndrome. At this point in time, we have the patient under anesthesia. We have ... and is not visible over a period of time. You can barely see a surgical scar. My ...

  7. Water Tunnel Facility

    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...

  8. INCAS TRISONIC WIND TUNNEL

    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.

  9. Carpal Tunnel Surgery

    Full Text Available ... tunnel pass the tendons and the nerves. So, right beneath this ligament is going to be the ... and it’s actually beneath this bridge of skin right in here. So, I’ve incised this ligament ...

  10. Carpal Tunnel Surgery

    Full Text Available ... the lining of the tendons that will sometimes increase in size, giving rise to the increased pressure --. ... incriminating structure in carpal tunnel syndrome. As it increases in size, the pressures within the carpal canal ...

  11. Wind Tunnel Testing Facilities

    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. Tunnelling in organic superconductors

    Bolech, C. J.; Giamarchi, T.

    2005-01-01

    We discuss the possibility of deciding on the symmetry of the superconducting phase in the organic superconductors (Bechgaard salts), using tunnelling experiments. We first briefly review the properties of organic superconductors, and the possibility to have unconventional (triplet) superconductivity in these systems. We then present a simple scheme for computing the full current-voltage characteristics for tunnelling experiments within the framework of the non-equilibrium Keldysh Green funct...

  13. On tunneling across horizons

    Vanzo, Luciano

    2011-01-01

    The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of various critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method isfree from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continu...

  14. Temperature stratification in tunnels

    Nyman, Hans; Ingason, Haukur

    2012-01-01

    An investigation of previously established correlations between gas temperature distribution and smoke stratification in mines has been carried out for tunnel applications. The investigated correlations are based on excess gas temperature ratios and Froude number scaling. This paper describes a comparison between two large scale tests carried out in a road tunnel and two well defined model scale tests. In each of the tests, a longitudinal flow was maintained. The temperature data obtained at ...

  15. Gravity Tunnel Drag

    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...

  16. Tunnelling of a molecule

    A quantum-mechanical description of tunnelling is presented for a one-dimensional system with internal oscillator degrees of freedom. The 'charged diatomic molecule' is frustrated on encountering a barrier potential by its centre of charge not being coincident with its centre of mass, resulting in transitions amongst internal states. In an adiabatic limit, the tunnelling of semiclassical coherent-like oscillator states is shown to exhibit the Hartman and Bueuttiker-Landauer times tH and tBL, with the time dependence of the coherent state parameter for the tunnelled state given by α(t) = α e-iω(t+Δt) , Δt = tH - itBL. A perturbation formalism is developed, whereby the exact transfer matrix can be expanded to any desired accuracy in a suitable limit. An 'intrinsic' time, based on the oscillator transition rate during tunnelling, transmission or reflection, is introduced. In simple situations the resulting intrinsic tunnelling time is shown to vanish to lowest order. In the general case a particular (nonzero) parametrisation is inferred, and its properties discussed in comparison with the literature on tunnelling times for both wavepackets and internal clocks. Copyright (1998) CSIRO Australia

  17. Numerical wind tunnels

    Souza, Paulo Victor Santos

    2015-01-01

    Flow of viscous fluids are not usually discussed in detail in general and basic courses of physics. This is due in part to the fact that the Navier-Stokes equation has analytical solution only for a few restricted cases, while more sophisticated problems can only be solved by numerical methods. In this text, we present a computer simulation of wind tunnel, i.e., we present a set of programs to solve the Navier-Stokes equation for an arbitrary object inserted in a wind tunnel. The tunnel enables us to visualize the formation of vortices behind object, the so-called von K\\'arm\\'an vortices, and calculate the drag force on the object. We believe that this numerical wind tunnel can support the teacher and allow a more elaborate discussion of viscous flow. The potential of the tunnel is exemplified by the study of the drag on a simplified model of wing whose angle of attack can be controlled. A link to download the programs that make up the tunnel appears at the end.

  18. The Beginner's Guide to Wind Tunnels with TunnelSim and TunnelSys

    Benson, Thomas J.; Galica, Carol A.; Vila, Anthony J.

    2010-01-01

    The Beginner's Guide to Wind Tunnels is a Web-based, on-line textbook that explains and demonstrates the history, physics, and mathematics involved with wind tunnels and wind tunnel testing. The Web site contains several interactive computer programs to demonstrate scientific principles. TunnelSim is an interactive, educational computer program that demonstrates basic wind tunnel design and operation. TunnelSim is a Java (Sun Microsystems Inc.) applet that solves the continuity and Bernoulli equations to determine the velocity and pressure throughout a tunnel design. TunnelSys is a group of Java applications that mimic wind tunnel testing techniques. Using TunnelSys, a team of students designs, tests, and post-processes the data for a virtual, low speed, and aircraft wing.

  19. Medical history of carpal tunnel syndrome.

    Michelsen, Heidi; Posner, Martin A

    2002-05-01

    The anatomical configuration of the carpal tunnel is that of an inelastic channel. Consequently, any increase in its volume or alteration in shape will usually result in a significant increase in interstitial pressure. At a pressure threshold of 20 mm Hg to 30 mm Hg, epineurial blood flow is compromised. When that pressure is sustained, the symptoms and physical findings associated with CTS appear. Typically, patients present with intermittent pain and paresthesias in all or part of the median nerve distribution of their hand(s). As weeks and months pass, symptoms progressively increase in frequency and severity. Eventually, thenar muscle weakness develops that initially manifests itself as "fatigue," or "tiredness." The progressive increase in symptoms and physical findings, usually accompanied by a progressive deterioration in electrodiagnostic studies, facilitates the classification of the condition into early, intermediate, and advanced stages. The increase in interstitial pressure in the carpal tunnel is in the vast majority of cases idiopathic (spontaneous). It can also be caused by a myriad of other conditions that can be classified into three other categories: intrinsic factors that increase the volume of the tunnel (outside and inside the nerve), extrinsic factors that alter the contour of the tunnel, and repetitive/overuse conditions. In addition, there is another category of neuropathic factors that affect the nerve without increasing interstitial pressure. In rare situations CTS can present as an acute problem. Far less common than the chronic form of the condition, it can follow acute wrist trauma, rheumatologic disorders, hemorrhagic problems, vascular disorders affecting a patent median artery, and high pressure injection injuries. Prompt recognition is important, followed in most cases by urgent surgical decompression of the median nerve. PMID:12371028

  20. Acute Bronchitis

    ... of bronchitis: acute and chronic. Most cases of acute bronchitis get better within several days. But your cough ... that cause colds and the flu often cause acute bronchitis. These viruses spread through the air when people ...

  1. Shot Noise in Magnetic Tunnel Junctions: Evidence for Sequential Tunneling

    Guerrero, R.; Aliev, F. G.; Tserkovnyak, Y.; Santos, T. S.; Moodera, J.S.

    2006-01-01

    We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels...

  2. Interaction between groundwater and TBM (Tunnel Boring Machine) excavated tunnels

    Font Capó, Jordi

    2012-01-01

    A number of problems, e.g. sudden inflows are encountered during tunneling under the piezometric level, especially when the excavation crosses high transmissivity areas. These inflows may drag materials when the tunnel crosses low competent layers, resulting in subsidence, chimney formation and collapses. Moreover, inflows can lead to a decrease in head level because of aquifer drainage. Tunnels can be drilled by a tunnel boring machine (TBM) to minimize inflows and groundwater impacts, restr...

  3. Tunneling Through Black Rings

    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.

  4. Tunneling with negative tension

    Marvel, Kate

    2008-01-01

    We describe a new family of thin-wall instantons, with negative tension bubble walls, that mediate tunneling between Minkowski or de Sitter vacua. Some of these instantons can have exponentially enhanced tunneling rates, and would dominate the Euclidean path integral, representing a severe non-perturbative instability in any theory which supports them. We give two constructions of these instantons in theories which are perturbatively stable, but violate the null energy condition. One construction uses a scalar field theory with higher-derivative kinetic term, and is similar to the Coleman-de Luccia positive tension instanton. The other construction employs a negative-tension boundary arising from Z_2 orbifolding: it resembles a "bubble of nothing" which nucleates and grows, consuming the surrounding de Sitter or Minkowski spacetime. We explain how the spectral flow for fluctutations about the thin-wall tunneling solutions automatically protects causality, for both positive and negative tension instantons. We ...

  5. Den Trygge Tunnel

    Jensen, Claus Bach; Hertz, Thea Stine Lund; Loose, Mikkel Thybo; Carlsson, Katrine; Høg, Lasse Noe; Andersen, Ea Leighton

    2013-01-01

    Abstract Pedestrian tunnels in Denmark has for a long time just been something that is solely there to transport the pedestrians away and in safety from car or train traffic, from one point to another, and it still is in many cases. There has been no focus on making it an experience in itself, actively including the pedestrians, which could promote comfort, pleasure and a feeling of safety when using the tunnels. They are left as they were build; creepy, dark, humid, wet and often vandali...

  6. Tunneling in Axion Monodromy

    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.

  7. Programmable ferroelectric tunnel memristor

    Andy eQuindeau; Dietrich eHesse; Marin eAlexe

    2014-01-01

    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...

  8. INCAS SUBSONIC WIND TUNNEL

    Corneliu STOICA; Corneliu OPREAN; Florin MUNTEANU

    2009-01-01

    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 an...

  9. Gap anisotropy and tunneling currents. [MPS3

    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......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...

  10. Carpal tunnel release

    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 endoscopic...

  11. Tunnelling with wormhole creation

    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.

  12. Tunnelling with wormhole creation

    Ansoldi, Stefano; Tanaka, Takahiro

    2014-01-01

    The description of quantum tunnelling in the presence of gravity shows subtleties in some cases. Here 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 literature.

  13. Environmental Wind Tunnels

    Jaňour, Zbyněk; Jurčáková, Klára

    New York : Nova Science Publishers, Inc., 2013 - (Chaplin, S.), s. 105-124 ISBN 978-1-62618-396-4 R&D Projects: GA MŠk(CZ) OC 113 Institutional support: RVO:61388998 Keywords : wind tunnel * air pollution * atmospheric boundary layer Subject RIV: BK - Fluid Dynamics

  14. Tunneling path toward spintronics

    The phenomenon of quantum tunneling, which was discovered almost a century ago, has led to many subsequent discoveries. One such discovery, spin polarized tunneling, was made 40 years ago by Robert Meservey and Paul Tedrow (Tedrow and Meservey 1971 Phys. Rev. Lett. 26 192), and it has resulted in many fundamental observations and opened up an entirely new field of study. Until the mid-1990s, this field developed at a steady, low rate, after which a huge increase in activity suddenly occurred as a result of the unraveling of successful spin tunneling between two ferromagnets. In the past 15 years, several thousands of papers related to spin polarized tunneling and transport have been published, making this topic one of the hottest areas in condensed matter physics from both fundamental science and applications viewpoints. Many review papers and book chapters have been written in the past decade on this subject. This paper is not exhaustive by any means; rather, the emphases are on recent progress, technological developments and informing the reader about the current direction in which this topic is moving.

  15. INCAS SUBSONIC WIND TUNNEL

    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.

  16. Monitoring pilot projects on bored tunnelling: the Second Heinenoord Tunnel and the Botlek Rail Tunnel

    Bakker, K.J.; De Boer, F.; Admiraal, J.B.M.; Van Jaarsveld, E.P.

    1999-01-01

    Two pilot projects for bored tunnelling in soft soil have been undertaken in the Netherlands. The monitoring was commissioned under the authority of the Centre for Underground Construction (COB). A description of the research related to the Second Heinenoord Tunnel and the Botlek Rail Tunnel will be

  17. [A woman with acute pain and swelling of her wrist

    Ridder, J.A. de; Koning, G.G.

    2015-01-01

    After hyperextension of both her wrists, a 39-year-old woman, who used coumarin derivatives for a known antiphospholipid syndrome, had acute pain and swelling of the left wrist. She had symptoms of an acute carpal tunnel syndrome. MRI revealed a hematoma compressing the median nerve in the carpal tu

  18. On tunneling across horizons

    Vanzo, L.

    2011-07-01

    The tunneling method for stationary black holes in the Hamilton-Jacobi variant is reconsidered in the light of some critiques that have been moved against. It is shown that once the tunneling trajectories have been correctly identified the method is free from internal inconsistencies, it is manifestly covariant, it allows for the extension to spinning particles and it can even be used without solving the Hamilton-Jacobi equation. These conclusions borrow support on a simple analytic continuation of the classical action of a pointlike particle, made possible by the unique assumption that it should be analytic in the complexified Schwarzschild or Kerr-Newman space-time. A more general version of the Parikh-Wilczek method will also be proposed along these lines.

  19. Magnetic flux tube tunneling

    We present numerical simulations of the collision and subsequent interaction of orthogonal magnetic flux tubes. The simulations were carried out using a parallelized spectral algorithm for compressible magnetohydrodynamics. It is found that, under a wide range of conditions, the flux tubes can open-quotes tunnelclose quotes through each other, a behavior not previously seen in studies of either vortex tube or magnetic flux tube interactions. Two conditions must be satisfied for tunneling to occur: the magnetic field must be highly twisted with a field line pitch >1, and the Lundquist number must be somewhat large, ≥2880. An examination of magnetic field lines suggests that tunneling is due to a double-reconnection mechanism. Initially orthogonal field lines reconnect at two specific locations, exchange interacting sections, and open-quotes passclose quotes through each other. The implications of these results for solar and space plasmas are discussed. copyright 1997 The American Physical Society

  20. Possibility of hyperbolic tunneling

    Traversable wormholes are primarily useful as 'gedanken experiments' and as a theoretician's probe of the foundations of general relativity. In this work, we analyze the possibility of having tunnels in a hyperbolic spacetime. We obtain exact solutions of static and pseudo-spherically symmetric spacetime tunnels by adding exotic matter to a vacuum solution referred to as a degenerate solution of class A. The physical properties and characteristics of these intriguing solutions are explored, and through the mathematics of embedding it is shown that particular constraints are placed on the shape function, that differ significantly from the Morris-Thorne wormhole. In particular, it is shown that the energy density is always negative, and the radial pressure is positive, at the throat, contrary to the Morris-Thorne counterpart. Specific solutions are also presented by considering several equations of state, and by imposing restricted choices for the shape function or the redshift function.

  1. Programmable ferroelectric tunnel memristor

    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.

  2. Tunnel boring machine applications

    This paper reports that characterization of Yucca Mountain for a potential repository requires construction of an underground Exploratory Studies Facility (ESF). Mechanical excavating methods have been proposed for construction of the ESF as they offer a number of advantages over drilling and blasting at the Yucca Mountain site, including; less ground disturbance and therefore a potential for less adverse effects on the integrity of the site, creation of a more stable excavation cross section requiring less ground support, and an inherently safer and cleaner working environment. The tunnel boring machine (TBM) provides a proven technology for excavating the welded and unwelded Yucca Mountain tuffs. The access ramps and main underground tunnels form the largest part of the ESF underground construction work, and have been designed for excavation by TBM

  3. Acute Pancreatitis and Pregnancy

    ... Acute Pancreatitis > Acute Pancreatitis and Pregnancy test Acute Pancreatitis and Pregnancy Timothy Gardner, MD Acute pancreatitis is ... of acute pancreatitis in pregnancy. Reasons for Acute Pancreatitis and Pregnancy While acute pancreatitis is responsible for ...

  4. Fire Size in Tunnels

    Carvel, Ricky O

    2004-01-01

    In recent years, a number of high profile accidental fires have occurred in several road and rail tunnels throughout the world. Many of these fires grew rapidly to catastrophic size and claimed many lives. The processes involved in the rapid growth and extremely severe of these fires are not adequately understood as yet. The introduction to this thesis reviews a number of these accidental fires and describes much of the previous experimental research which has brought about the...

  5. The beam dump tunnels

    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.

  6. Small Icing Wind Tunnel

    Horák, V.; Hoření, Bohumír; Rozehnal, D.; Svoboda, E.

    Brno: University of Defence, 2007, s. 91-98. ISBN 978-80-7231-238-2. [ICMT'07, The international conference on military technologies. Brno (CZ), 02.05.2007-04.05.2007] R&D Projects: GA MPO FT-TA/026 Institutional research plan: CEZ:AV0Z20600510 Keywords : aircraft icing * icing wind tunnel * ice accretion Subject RIV: JR - Other Machinery

  7. Resonant Tunneling Spin Pump

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  8. Tunnelling from black holes and tunnelling into white holes

    Chatterjee, Bhramar; Ghosh, A.; Mitra, P.

    2008-03-01

    Hawking radiation is nowadays being understood as tunnelling through black hole horizons. Here, the extension of the Hamilton-Jacobi approach to tunnelling for non-rotating and rotating black holes in different non-singular coordinate systems not only confirms this quantum emission from black holes but also reveals the new phenomenon of absorption into white holes by quantum mechanical tunnelling. The rôle of a boundary condition of total absorption or emission is also clarified.

  9. Fluctuation Dominated Josephson Tunneling with a Scanning Tunneling Microscope

    Naaman, O.; Teizer, W.; Dynes, R. C.

    2001-01-01

    We demonstrate Josephson tunneling in vacuum tunnel junctions formed between a superconducting scanning tunneling microscope tip and a Pb film, for junction resistances in the range 50-300 k$\\Omega$. We show that the superconducting phase dynamics is dominated by thermal fluctuations, and that the Josephson current appears as a peak centered at small finite voltages. In the presence of microwave fields (f=15.0 GHz) the peak decreases in magnitude and shifts to higher voltages with increasing ...

  10. Bronchitis - acute

    ... sharing features on this page, please enable JavaScript. Acute bronchitis is swelling and inflammation in the main passages ... present only for a short time. Causes When acute bronchitis occurs, it almost always comes after having a ...

  11. Bronchitis - acute

    Acute bronchitis is swelling and inflammation in the main passages that carry air to the lungs. The swelling narrows ... makes it harder to breathe. Another symptom of bronchitis is a cough. Acute means the symptoms have ...

  12. Acute Bronchitis

    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 ...

  13. Acute pancreatitis

    Bo-Guang Fan; Åke Andrén-Sandberg

    2010-01-01

    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 ingest...

  14. Acute pancreatitis

    Bo-Guang Fan; Åke Andrén-Sandberg

    2010-01-01

    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....

  15. Quantum tunneling in thermal medium

    Matsumoto, Sh.; Yoshimura, M.

    2000-01-01

    Time evolution of tunneling phenomena in medium is studied using a standard model of environment interaction. A semiclassical formula valid at low, but finite temperatures is derived in the form of integral transform for the reduced Wigner function, and the tunneling probability in thermal medium is calculated for a general tunneling potential of one dimensional system. Effect of dissipation, its time evolution in particular, depends on the behavior of the potential far beyond the barrier.

  16. Managerial Ownership Influencing Tunnelling Behaviour

    Agung Juliarto

    2013-06-01

    Full Text Available This study investigates the extent and the determinants of tunnelling behaviour in five ASEAN countries (i.e. Indonesia, Malaysia, Philippines, Singapore, and Thailand. Related party transactions (RPTs in the form of loans to related parties are used as the proxy for tunnelling. With 200 firm-year observations over the period 2006-2009, this study finds a positive association between managerial ownership and the extent of tunnelling.The other important findings are that business environment (BE, foreign ownership, and independent directors are ineffective governance mechanisms to rein in tunnelling behaviour. This suggests that regulators need to evolve more effective governance mechanisms.

  17. Image analysis of the distribution of tophus in ankle joint and tarsal joint%痛风患者踝跗关节痛风石沉积特点的影像学分析

    孙德政; 杨青; 胡亚彬; 段峰; 于华龙

    2014-01-01

    目的:应用多排螺旋 CT 对踝跗关节痛风石常见沉积部位进行分析,并对痛风发病机制进行探讨研究。方法对临床确诊34例踝跗关节痛风患者的双踝跗关节行 CT 平扫检查,其中55个踝跗关节可见痛风石沉积。将痛风石沉积部位分为韧带组、肌腱组及关节组,并分别对其进行记录、分析。结果韧带组中常见受累韧带依次为距腓前韧带(n=38)、内侧韧带(距骨跟骨端)(n=30)、距跟骨间韧带(n=29)(P <0.05)。肌腱组最常受累肌腱为跟腱(n=18),其次为胫骨后肌腱(n=7)(P <0.05)。关节组依次为楔间关节(n=15)、胫腓下关节(n=10)(P <0.05)。结论距腓前韧带为踝跗关节痛风石最常受累韧带,跟腱为最常受累肌腱。痛风石最易累及的关节为楔骨间关节。%Objective To analyze the distribution of tophus in ankle and tarsal joints by multislice spiral computed tomography (MSCT)and to explore the pathogenesis of gout.Methods 34 patients with a documented diagnosis of gout underwent CT examina-tion of bilateral ankle and tarsal joints,and 55 ankle and tarsal joints were observed tophus.The sites of tophus deposition were cate-gorized into groups of ligament,tendon and joint in order to record and analyze.Results The tophus were showed at the anterior talofibular ligament (n=38),the medial ligament (the site of talus and calcaneus)(n=30)and the interosseous talocalcaneal liga-ment (n=29)(P <0.05)in the group of ligament;at achilles tendon (n= 18),followed by tibialis posterior tendon (n= 7)(P <0.05)in the group of tendon;at articulations intercuneiformes (n=1 5)and inferior tibiofibular articulation (n= 10)(P <0.05 )in the group of joint.Conclusion In ankle and tarsal joints,tophus is commonly deposited at the anterior talofibular ligament,at the achilles tendon and the articulationes intercuneiformes.

  18. Thermovoltages in vacuum tunneling investigated by scanning tunneling microscopy

    Hoffmann, D. H.; Rettenberger, Armin; Grand, Jean Yves; Läuger, K.; Leiderer, Paul; Dransfeld, Klaus; Möller, Rolf

    1995-01-01

    By heating the tunneling tip of a scanning tunneling microscope the thermoelectric properties of a variable vacuum barrier have been investigated. The lateral variation of the observed thermovoltage will be discussed for polycrystalline gold, stepped surfaces of silver, as well as for copper islands on silver.

  19. Acute pancreatitis

    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.

  20. Acute pancreatitis

    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.

  1. Traversal time for tunnelling

    We give here a simple approach to study the traversal time for tunnelling. We make use of the WKB wave functions to evaluate the velocity field of particles in the barrier region and obtain an expression for traversal time given by ∫dx[m/2(V(x)-E)]sup(1/2). This coincides with the expression given by recent approaches which determine traversal time by studying transmission of particles through a time-modulated rectangular barrier and by studying the extent of Larmor precession of particles through a rectangular barrier in the presence of a magnetic field. (author)

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

    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. A virtual detector approach to tunnel ionization and tunneling times

    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.

  4. Carpal tunnel syndrome - Part II (treatment,

    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%.

  5. Tunneling Ionization of Diatomic Molecules

    Svensmark, Jens Søren Sieg

    2016-01-01

    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...

  6. The Langley Wind Tunnel Enterprise

    Paulson, John W., Jr.; Kumar, Ajay; Kegelman, Jerome T.

    1998-01-01

    After 4 years of existence, the Langley WTE is alive and growing. Significant improvements in the operation of wind tunnels have been demonstrated and substantial further improvements are expected when we are able to truly address and integrate all the processes affecting the wind tunnel testing cycle.

  7. Tunnel electroresistance through organic ferroelectrics

    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.

  8. Tunnel electroresistance through organic ferroelectrics.

    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

    2016-01-01

    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. PMID:27143121

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

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

    2011-01-01

    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 (MRI) to derive the relationship between carpal tunnel pressure and morphological ...

  10. Tunnelling microscopy of DNA

    Selci, Stefano; Cricenti, Antonio

    1991-01-01

    Uncoated DNA molecules marked with an activated tris (1-aziridinyl) phosphine oxide (TAPO) solution were deposited on gold substrates and imaged in air with a high resolution Scanning Tunnelling Microscope (STM). The STM operated simultaneously in the constant-current and gap-modulated mode. Highly reproducible STM images have been obtained and interpreted in terms of expected DNA structure. The main periodicity, regularly presented in molecules several hundred Ångstrom long, ranges from 25 Å to 35 Å with an average diameter of 22 Å. Higher resolution images of the minor groove have revealed the phosphate groups along the DNA backbones. Constant-current images of TAPO deposited on gold show a crystalline structure of rows of molecules with a side-by-side spacing of 3 Å.

  11. Tunneling times with covariant measurements

    Kiukas, J; Werner, R F; 10.1007/s10701-009-9275-z

    2009-01-01

    We consider the time delay of massive, non-relativistic, one-dimensional particles due to a tunneling potential. In this setting the well-known Hartman effect asserts that often the sub-ensemble of particles going through the tunnel seems to cross the tunnel region instantaneously. An obstacle to the utilization of this effect for getting faster signals is the exponential damping by the tunnel, so there seems to be a trade-off between speedup and intensity. In this paper we prove that this trade-off is never in favor of faster signals: the probability for a signal to reach its destination before some deadline is always reduced by the tunnel, for arbitrary incoming states, arbitrary positive and compactly supported tunnel potentials, and arbitrary detectors. More specifically, we show this for several different ways to define ``the same incoming state'' and ''the same detector'' when comparing the settings with and without tunnel potential. The arrival time measurements are expressed in the time-covariant appr...

  12. Mars Surface Tunnel Element Concept

    Rucker, Michelle A.; Jefferies, Sharon; Howe, A. Scott; Howard, Robert; Mary, Natalie; Watson, Judith; Lewis, Ruthan

    2016-01-01

    When the first human visitors on Mars prepare to return to Earth, they will have to comply with stringent planetary protection requirements. Apollo Program experience warns that opening an EVA hatch directly to the surface will bring dust into the ascent vehicle. To prevent inadvertent return of potential Martian contaminants to Earth, careful consideration must be given to the way in which crew ingress their Mars Ascent Vehicle (MAV). For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel that eliminates extravehicular activity (EVA) ingress is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications, such as rover to habitat transfer, once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The study team began by identifying the minimum set of functional requirements needed for the tunnel to perform its primary mission, as this would presumably be the simplest design, with the lowest mass and volume. This Minimum Functional Tunnel then becomes a baseline against which various tunnel design concepts and potential alternatives can be traded, and aids in assessing the mass penalty of increased functionality. Preliminary analysis indicates that the mass of a single-mission tunnel is about 237 kg, not including mass growth allowance.

  13. Tunneling spectroscopy of novel superconductors

    Recent discoveries of exciting new superconductors have led to further exciting speculations about novel mechanisms and/or pairing. Tunneling spectroscopy can again play an important role in establishing the applicability of these ideas to specific superconductors. In addition to the traditional role of verifying in detail the electron-phonon coupling through α2F, in many cases the magnitude of the gap compared to the BCS prediction or the crystalline gap anisotropy can reveal direct information about novel mechanisms and/or pairing. Since many of these new materials have only been available as bulk samples, or bulk single-crystal studies are desired, the technique of vacuum tunneling spectroscopy, pioneered by Poppe (1981) for superconductors, is most appropriate. However, thick, nonconducting surface layers are often found which prevent true vacuum tunneling. For these samples, mechanical contact of the tunneling tip is required to break through the surface layer to the superconductor below. The resulting point-contact tunneling can, however, emulate many of the results of true tunneling through a vacuum or insulator. In this paper, they shall briefly review relevant tunneling techniques and some recent experiments on magnetic, organic, heavy fermion and high-T/sub c/ oxide superconductors. Connections are made to theoretical ideas, especially regarding novel mechanisms and/or pairing

  14. Optical Detection of Tunneling Ionization

    Verhoef, Aart J.; Mitrofanov, Alexander V.; Serebryannikov, Evgenii E.; Kartashov, Daniil V.; Zheltikov, Aleksei M.; Baltuška, Andrius

    2010-04-01

    We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

  15. Optical Detection of Tunneling Ionization

    We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

  16. Tunneling inhibition for subwavelength light

    Huang, Changming; Ye, Fangwei; Kartashov, Yaroslav V; Chen, Xianfeng; Torner, Lluis

    2013-01-01

    We show that light tunneling inhibition may take place in suitable dynamically modulated waveguide arrays for light spots whose features are remarkably smaller than the wavelength of light. We found that tunneling between neighboring waveguides can be suppressed for specific frequencies of the out-of-phase refractive index modulation, affording undistorted propagation of the input subwavelength light spots over hundreds of Rayleigh lengths. Tunneling inhibition turns out to be effective only when the waveguide separation in the array is above a critical threshold. Inclusion of a weak focusing nonlinearity is shown to improve localization. We analyze the phenomenon in purely dielectric structures and also in arrays containing periodically spaced metallic layers.

  17. Resonant torus-assisted tunneling.

    Yi, Chang-Hwan; Yu, Hyeon-Hye; Kim, Chil-Min

    2016-01-01

    We report a new type of dynamical tunneling, which is mediated by a resonant torus, i.e., a nonisolated periodic orbit. To elucidate the phenomenon, we take an open elliptic cavity and show that a pair of resonances localized on two classically disconnected tori tunnel through a resonant torus when they interact with each other. This so-called resonant torus-assisted tunneling is verified by using Husimi functions, corresponding actions, Husimi function distributions, and the standard deviations of the actions. PMID:26871067

  18. Tunneling of atoms, nuclei and molecules

    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.

  19. Tunneling progress on the Yucca Mountain Project

    The current status of tunneling progress on the Yucca Mountain Project (YMP) is presented in this paper. The Exploratory Studies Facility (ESF), a key part of the YMP, has been long in development and construction is ongoing. This is a progress report on the tunneling aspects of the ESF as of January 1, 1996. For purposes of discussion in this summary, the tunneling has progressed in four general phases. The paper describes: tunneling in jointed rock under low stress; tunneling through the Bow Ridge Fault and soft rock; tunneling through the Imbricate Fault Zone; and Tunneling into the candidate repository formation

  20. Predicting Tunneling-Induced Ground Movement

    Laefer, Debra F.; Kim, Wan

    2004-01-01

    Cost-effective and permissible tunneling can occur only if ground movement prediction is refined to accommodate changes in both the urban environment and tunneling technology. As cities age, tunnels are being installed closer to existing structures and in increasingly complicated belowground conditions. The reality of stacked tunnels, abandoned facilities, and more extensive use of underground space raises the question of whether relationships derived for single open-shield tunnels in free-fi...

  1. Analytic Solutions of Elastic Tunneling Problems

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane. Such problems are encountered in geomechanics during the excavation of tunnels. When tunnels are excavated the removal of the weighted material inside the tunnel causes the ground under the tunnel to...

  2. Self-Organizing Tunnel Peers

    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.

  3. Electron tunneling in proteins program.

    Hagras, Muhammad A; Stuchebrukhov, Alexei A

    2016-06-01

    We developed a unique integrated software package (called Electron Tunneling in Proteins Program or ETP) which provides an environment with different capabilities such as tunneling current calculation, semi-empirical quantum mechanical calculation, and molecular modeling simulation for calculation and analysis of electron transfer reactions in proteins. ETP program is developed as a cross-platform client-server program in which all the different calculations are conducted at the server side while only the client terminal displays the resulting calculation outputs in the different supported representations. ETP program is integrated with a set of well-known computational software packages including Gaussian, BALLVIEW, Dowser, pKip, and APBS. In addition, ETP program supports various visualization methods for the tunneling calculation results that assist in a more comprehensive understanding of the tunneling process. © 2016 Wiley Periodicals, Inc. PMID:26990540

  4. Free Surface Water Tunnel (FSWT)

    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...

  5. Flatback airfoil wind tunnel experiment.

    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.

  6. Tunnel construction for a desertron

    The tunnel in this model of construction is 3-1/2 feet wide by 5 feet high. It is assumed that the tunnel contains a rail system and guidance system for: (1) An enclosed car used for transport of 2 people and some tools. (2) A magnet mover. This robot could pick up a magnet and transport it at about 10 miles per hour. (3) An alignment robot. The alignment robot would intercept E.M. waves (microwaves, lasers) to determine its position in the tunnel. Then workers could come along inside the tunnel hoop and nail it together and to the floor. The trench would then be back-filled with a 1 foot berm on top. A rail system would be installed and a support stand for the magnet

  7. Quantum tunneling through graphene nanorings

    Wu Zhenhua; Zhang, Z Z; Chang Kai [SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, PO Box 912, 100083 Beijing (China); Peeters, F M, E-mail: kchang@red.semi.ac.cn [Department of Physics, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2010-05-07

    We investigate theoretically quantum transport through graphene nanorings in the presence of a perpendicular magnetic field. Our theoretical results demonstrate that the graphene nanorings behave like a resonant tunneling device, contrary to the Aharonov-Bohm oscillations found in conventional semiconductor rings. The resonant tunneling can be tuned by the Fermi energy, the size of the central part of the graphene nanorings and the external magnetic field.

  8. Quantum tunneling through graphene nanorings

    We investigate theoretically quantum transport through graphene nanorings in the presence of a perpendicular magnetic field. Our theoretical results demonstrate that the graphene nanorings behave like a resonant tunneling device, contrary to the Aharonov-Bohm oscillations found in conventional semiconductor rings. The resonant tunneling can be tuned by the Fermi energy, the size of the central part of the graphene nanorings and the external magnetic field.

  9. Quantum tunneling through graphene nanorings

    Wu, Zhenhua; Zhang, Z. Z.; Chang, Kai; Peeters, F. M.

    2010-05-01

    We investigate theoretically quantum transport through graphene nanorings in the presence of a perpendicular magnetic field. Our theoretical results demonstrate that the graphene nanorings behave like a resonant tunneling device, contrary to the Aharonov-Bohm oscillations found in conventional semiconductor rings. The resonant tunneling can be tuned by the Fermi energy, the size of the central part of the graphene nanorings and the external magnetic field.

  10. Vision Therapy Procedures for Tunneling

    Jeffrey H. Getzell, OD

    2015-08-01

    Full Text Available Tunneling is a form of an exclusive concentration and is a common spatial adaptation. Treatment strategies for tunneling and the overall visual process will be addressed. Strategies include diaphragmatic breathing, syntonics, and vision therapy activities that stress working in real space with lenses and prisms. Objectives, observations, expected responses, modifications, and questions for the patient are discussed for each vision therapy activity.

  11. Wildlife Tunnel Enhances Population Viability

    Michael McCarthy; Dean Heinze; Rodney van der Ree; Ian Mansergh

    2009-01-01

    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 f...

  12. Direct, coherent and incoherent intermediate state tunneling and scanning tunnel microscopy (STM)

    Theory and experiment in tunneling are still qualitative in nature, which hold true also for the latest developments in direct-, resonant-, coherent- and incoherent-tunneling. Those tunnel processes have recently branched out of the field of ''solid state tunnel junctions'' into the fields of scanning tunnel microscopy (STM), single electron tunneling (SET) and semiconducting resonant tunnel structures (RTS). All these fields have promoted the understanding of tunneling in different ways reaching from the effect of coherence, of incoherence and of charging in tunneling, to spin flip or inelastic effects. STM allows not only the accurate measurements of the tunnel current and its voltage dependence but, more importantly, the easy quantification via the (quantum) tunnel channel conductance and the distance dependence. This new degree of freedom entering exponentially the tunnel current allows an unique identification of individual tunnel channels and their quantification. In STM measurements large tunnel currents are observed for large distances d > 1 nm explainable by intermediate state tunneling. Direct tunneling with its reduced tunnel time and reduced off-site Coulomb charging bridges distances below 1 nm, only. The effective charge transfer process with its larger off-site and on-site charging at intermediate states dominates tunnel transfer in STM, biology and chemistry over distances in the nm-range. Intermediates state tunneling becomes variable range hopping conduction for distances larger than d > 2 nm, for larger densities of intermediate states n1(ε) and for larger temperatures T or voltages U, still allowing high resolution imaging

  13. Scanning Tunneling Optical Resonance Microscopy

    Bailey, Sheila; Wilt, Dave; Raffaelle, Ryne; Gennett, Tom; Tin, Padetha; Lau, Janice; Castro, Stephanie; Jenkins, Philip; Scheiman, Dave

    2003-01-01

    Scanning tunneling optical resonance microscopy (STORM) is a method, now undergoing development, for measuring optoelectronic properties of materials and devices on the nanoscale by means of a combination of (1) traditional scanning tunneling microscopy (STM) with (2) tunable laser spectroscopy. In STORM, an STM tip probing a semiconductor is illuminated with modulated light at a wavelength in the visible-to-near-infrared range and the resulting photoenhancement of the tunneling current is measured as a function of the illuminating wavelength. The photoenhancement of tunneling current occurs when the laser photon energy is sufficient to excite charge carriers into the conduction band of the semiconductor. Figure 1 schematically depicts a proposed STORM apparatus. The light for illuminating the semiconductor specimen at the STM would be generated by a ring laser that would be tunable across the wavelength range of interest. The laser beam would be chopped by an achromatic liquid-crystal modulator. A polarization-maintaining optical fiber would couple the light to the tip/sample junction of a commercial STM. An STM can be operated in one of two modes: constant height or constant current. A STORM apparatus would be operated in the constant-current mode, in which the height of the tip relative to the specimen would be varied in order to keep the tunneling current constant. In this mode, a feedback control circuit adjusts the voltage applied to a piezoelectric actuator in the STM that adjusts the height of the STM tip to keep the tunneling current constant. The exponential relationship between the tunneling current and tip-to-sample distance makes it relatively easy to implement this mode of operation. The choice of method by which the photoenhanced portion of the tunneling current would be measured depends on choice of the frequency at which the input illumination would be modulated (chopped). If the frequency of modulation were low enough (typically < 10 Hz) that the

  14. An Unusual Presentation of Acute Calcific Tendinitis in the Hand

    Harris, Albert R.; McNamara, Terrence R.; Brault, Jeffrey S.; Rizzo, Marco

    2008-01-01

    Acute calcific tendinitis (ACT) is a relatively uncommon disorder of the hand and wrist. ACT is a well-known condition of the shoulder, but it often goes unrecognized when occurring in the hand or wrist. The overall lack of familiarity along with the non-specific symptoms associated with ACT frequently leads to misdiagnosis or delay in diagnosis. We report a case of acute calcific tendinitis occurring in the carpal tunnel which is a rare presentation.

  15. Acute pancreatitis

    ... page: //medlineplus.gov/ency/article/000287.htm Acute pancreatitis To use the sharing features on this page, ... fatty foods after the attack has improved. Outlook (Prognosis) Most cases go away in a week. However, ...

  16. Acute Pericarditis

    ... Sugar Control Helps Fight Diabetic Eye Disease Are 'Workaholics' Prone to OCD, Anxiety? ALL NEWS > Resources First ... cancer, or heart surgery, the fluid is blood. Causes Acute pericarditis usually results from infection or other ...

  17. Acute dyspnea

    Radiodiagnosis is applied to determine the causes of acute dyspnea. Acute dyspnea is shown to aggravate the course of pulmonary diseases (bronchial asthma, obstructive bronchitis, pulmonary edema, throboembolism of pulmonary arteries etc) and cardiovascular diseases (desiseas of myocardium). The main tasks of radiodiagnosis are to determine volume and state of the lungs, localization and type of pulmonary injuries, to verify heart disease and to reveal concomitant complications

  18. Bronchitis (acute)

    Wark, Peter

    2008-01-01

    Acute bronchitis, with transient inflammation of the trachea and major bronchi, affects over 40/1000 adults a year in the UK. The causes are usually considered to be infective, but only around half of people have identifiable pathogens.The role of smoking or environmental tobacco smoke inhalation in predisposing to acute bronchitis is unclear.A third of people may have longer-term symptoms or recurrence.

  19. National Wind Tunnel Complex (NWTC)

    1996-01-01

    The National Wind Tunnel Complex (NWTC) Final Report summarizes the work carried out by a unique Government/Industry partnership during the period of June 1994 through May 1996. The objective of this partnership was to plan, design, build and activate 'world class' wind tunnel facilities for the development of future-generation commercial and military aircraft. The basis of this effort was a set of performance goals defined by the National Facilities Study (NFS) Task Group on Aeronautical Research and Development Facilities which established two critical measures of improved wind tunnel performance; namely, higher Reynolds number capability and greater productivity. Initial activities focused upon two high-performance tunnels (low-speed and transonic). This effort was later descoped to a single multipurpose tunnel. Beginning in June 1994, the NWTC Project Office defined specific performance requirements, planned site evaluation activities, performed a series of technical/cost trade studies, and completed preliminary engineering to support a proposed conceptual design. Due to budget uncertainties within the Federal government, the NWTC project office was directed to conduct an orderly closure following the Systems Design Review in March 1996. This report provides a top-level status of the project at that time. Additional details of all work performed have been archived and are available for future reference.

  20. TunnelVision: LHC Tunnel Photogrammetry System for Structural Monitoring

    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.

  1. Acute myelogenous leukemia (AML) - children

    Acute myelogenous leukemia - children; AML; Acute myeloid leukemia - children; Acute granulocytic leukemia - children; Acute myeloblastic leukemia - children; Acute non-lymphocytic leukemia (ANLL) - children

  2. Computational multiqubit tunnelling in programmable quantum annealers

    Boixo, Sergio; Smelyanskiy, Vadim N.; Shabani, Alireza; Isakov, Sergei V.; Dykman, Mark; Denchev, Vasil S.; Amin, Mohammad H.; Smirnov, Anatoly Yu; Mohseni, Masoud; Neven, Hartmut

    2016-01-01

    Quantum tunnelling is a phenomenon in which a quantum state traverses energy barriers higher than the energy of the state itself. Quantum tunnelling has been hypothesized as an advantageous physical resource for optimization in quantum annealing. However, computational multiqubit tunnelling has not yet been observed, and a theory of co-tunnelling under high- and low-frequency noises is lacking. Here we show that 8-qubit tunnelling plays a computational role in a currently available programmable quantum annealer. We devise a probe for tunnelling, a computational primitive where classical paths are trapped in a false minimum. In support of the design of quantum annealers we develop a nonperturbative theory of open quantum dynamics under realistic noise characteristics. This theory accurately predicts the rate of many-body dissipative quantum tunnelling subject to the polaron effect. Furthermore, we experimentally demonstrate that quantum tunnelling outperforms thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive.

  3. Tunneling field effect transistor technology

    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.

  4. Fermion Tunneling from Dynamical Horizons

    Di Criscienzo, Roberto

    2008-01-01

    The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.

  5. Spin tunnelling in mesoscopic systems

    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.

  6. Quantum Cosmology for Tunneling Universes

    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.

  7. Observation of spin-polarized tunneling by scanning tunneling microscopy

    The tunneling magnetoresistance (TMR) in ferromagnet-vacuum-ferromagnet junction was studied by using an STM setup. After in situ cleaning of both of two ferromagnetic electrodes, up to 20% of TMR was observed. Such a signal was not observed for air gap nor nonmagnetic electrode. This technique is suitable for basic research of the TMR effect

  8. Acute myocardial infarction in a young adult with myocardial bridging and normal coronary arteries

    Moris Chansky; Adriana Regina Perez; Nilo Lima

    2004-01-01

    The authors present a case of a young adult with acute myocardialinfarction, attended at the Emergency Department of HospitalIsraelita Albert Einstein. Acute myocardial infarction caused bymyocardial bridge (intramyocardial tunneled coronary artery) is arare clinical entity. The finding of this condition in patients withnormal arteries (non-obstructed vessels) is uncommon; it isusually associated with extracardiac triggering factors. The casereported presented an acute myocardial infarction c...

  9. Palladium Electrodes for Molecular Tunnel Junctions

    Chang, Shuai; Sen, Suman; Zhang, Peiming; Gyarfas, Brett; Ashcroft, Brian; Lefkowitz, Steven; Peng, Hongbo; Lindsay, Stuart

    2012-01-01

    Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with CMOS fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More ...

  10. Dynamic Analysis of Esfahan Metro Tunnels

    Bagherzadeh, A.; Ferdowsi, B.

    2009-01-01

    This study discusses the modeling of Esfahan metro tunnels subjected to earthquake and interaction of tunnels. In critical structures like subway tunnels, performing a time history dynamic analysis is the only acceptable method for determining the seismic-induced forces. For sites with no recorded earthquake ground motion, artificially generated accelerograms to represent the real earthquake records has been suggested by many experts. This study addressed the modeling of metro tunnels s...

  11. Fiber coupled ultrafast scanning tunneling microscope

    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 substrate. By using a firmly attached fiber we achieve an excellent reproducibility and unconstrained positioning of the tip. We observe a transient signal with 2.9 ps pulse width in tunneling mode and 5...

  12. Tunneling Processes in Optically Excited Quantum Dots

    LI Xiu-Ping; WEI Hua-Rong; XU Li-Ping; GONG Jian-Ping; YAN Wei-Xian

    2011-01-01

    The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts: the electron and the hole parts, which are analytically obtained in the framework of the Keldysh formalism. The tunneling process is selective tunneling, which results in dark tunneling states. The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.%The single-electron tunneling processes in optically excited coupled quantum dots can be divided into two parts:the electron and the hole parts,which are analytically obtained in the framework of the Keldysh formalism.The tunneling process is selective tunneling,which results in dark tunneling states.The tunneling currents are co-determined by the resonance energies and probability distributions of the particular quantum channels defined by the electron-hole complex resonant states.Probing the fine-energy structure of the exciton complexes[1-10] in an optically excited quantum dot is an important way of exploring new mechanisms in nanostructures.Single electron tunneling (SET) devices consisting of a central quantum dot (QD) and a tunneling coupled source and drain have become important optoelectronic nano-devices.[11,12

  13. Fiber coupled ultrafast scanning tunneling microscope

    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...

  14. Barrier properties of HTSC tunnel junctions

    It was found that the overall shape of the normal state tunnel conductance of metal oxides with low Fermi energies is very sensitive to the barrier height and thickness. It was shown that this curve can differ considerably from the usual tunnel characteristics known from the tunnel spectroscopy of conventional metal

  15. Tunnel Face Stability & New CPT Applications

    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

  16. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q ∼ 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement

  17. Inelastic scattering in resonant tunneling

    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...

  18. Josephson tunnel junction microwave attenuator

    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 biased...

  19. Mars Surface Tunnel Element Concept

    Rucker, Michelle A.; Mary, Natalie; Howe, A. Scott; Jeffries, Sharon

    2016-01-01

    How Mars surface crews get into their ascent vehicle has profound implications for Mars surface architecture. To meet planetary protection protocols, the architecture has get Intravehicular Activity (IVA)-suited crew into a Mars Ascent Vehicle (MAV) without having to step outside into the Mars environment. Pushing EVA suit don/doff and EVA operations to an element that remains on the surface also helps to minimize MAV cabin volume, which in turn can reduce MAV cabin mass. Because the MAV will require at least seven kilograms of propellant to ascend each kilogram of cabin mass, minimal MAV mass is desired. For architectures involving more than one surface element-such as an ascent vehicle and a pressurized rover or surface habitat-a retractable tunnel is an attractive solution. Beyond addressing the immediate MAV access issue, a reusable tunnel may be useful for other surface applications once its primary mission is complete. A National Aeronautics and Space Administration (NASA) team is studying the optimal balance between surface tunnel functionality, mass, and stowed volume as part of the Evolvable Mars Campaign (EMC). The "Minimum Functional Tunnel" is a conceptual design that performs a single function. Having established this baseline configuration, the next step is to trade design options, evaluate other applications, and explore alternative solutions.

  20. Wormhole creation by quantum tunnelling

    Battarra, Lorenzo; Lehners, Jean-Luc

    2016-01-01

    We study the process of quantum tunnelling in self-interacting scalar field theories with non-minimal coupling to gravity. In these theories gravitational instantons can develop a neck -- a feature prohibited in theories with minimal coupling, and describing the nucleation of geometries containing a wormhole. We also clarify the relationship of neck geometries to violations of the null energy condition.

  1. Quantum Tunneling in Black Holes

    Majhi, Bibhas Ranjan

    2011-01-01

    This thesis is focussed towards the applications of the quantum tunneling mechanism to study black holes. Here we give a general frame work of the existing tunneling mechanism, both the radial null geodesic and Hamilton Jacobi methods. On the radial null geodesic method side, we study the modifications to the tunneling rate, Hawking temperature and the Bekenstein- Hawking area law by including the back reaction as well as non-commutative effects in the space-time. A reformulation of the Hamilton-Jacobi (HJ) method is first introduced. Based on this, a close connection between the quantum tunneling and the gravitational anomaly mechanisms to discuss Hawking effect, is put forwarded. An interesting advantage of this reformulated HJ method is that one can get directly the emission spectrum from the event horizon of the black hole, which was missing in the earlier literature. Also, the quantization of the entropy and area of a black hole is discussed in this method. Another part of the thesis is the introduction ...

  2. Earth Pressure on Tunnel Crown

    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...

  3. Apparent tunneling in chemical reactions

    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...

  4. Introduction to scanning tunneling microscopy

    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.

  5. Apparent tunneling in chemical reactions

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

    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...

  6. Quantum Tunneling and Back Reaction

    Banerjee, Rabin; Majhi, Bibhas Ranjan

    2007-01-01

    We give a correction to the tunneling probability by taking into account the back reaction effect to the metric of the black hole spacetime. We then show how this gives rise to the modifications in the semiclassical black hole entropy and Hawking temperature. Finally, we reproduce the familiar logarithmic correction to the Bekenstein-Hawking area law.

  7. Installation in the SPS tunnel

    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

  8. Time tunnels meet warped passages

    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)

  9. Light emission in tunneling processes

    We introduce a new method for mapping and analyzing (with atomic resolution) molecules adsorbed on surfaces. This method relies on the detection of fluorescence from molecules, electronically excited by inelastic tunneling in STM. It may combines the excellent spatial resolution of STM together with the specificity of fluorescence as an analytical tool. We propose to overcome this problem by choosing 'transparent conductors' (such as Indium Tin Oxides-lTO) as the STM substrate. ITO, characterized by a large optical gap, will not quench electronically excited molecules. We have tested our idea to enhance the quantum efficiency of molecular emission on surfaces by using transparent conductors in the tunneling junction. We have constructed large area tunnel-junctions by using the squeezable tunnel-Junction technique. The principle of this technique is to squeeze together smooth flat surfaces separated by a thin spacer. By applying a controlled force, junctions with surface area of thousands of square angstroms are made. We have recorded light emission from bare tunneling surfaces and from surfaces coated with molecules (DCA, DCM and COUMARINE), as a function of the bias voltage in the range of 0-5 volts. Typical tunneling currents are 50 nano ampere. Our main findings are: The bare ITO surface emits light at biasing voltages larger than 4.0 eV which corresponds to electron-hole excitation over the optical gap of ITO. ITO surfaces coated with chromophore molecules have shown enhanced light emission at a voltage bias which corresponds to the allowed excitations energies in the chromophore. A voltage bias of 2-5 V yielded light emission of 5 * 103 photon/μC. The corresponding metallic surfaces, bare or coated with a chromophore did not show any emission. In order to test the possibility of using this effect for imaging purposes we have replaced one electrode of junction with an ITO coated glass tip of 180 μm radius. such a tip yield an upper limit of tunneling area of

  10. Photon Aided and Inhibited Tunneling of Photons

    liu, xuele

    2013-01-01

    In the light of the interest in the transport of single photons in arrays of waveguides, fiber couplers, photonic crystals, etc., we consider the quantum mechanical process of the tunneling of photons through evanescently or otherwise coupled structures. We specifically examine the issue of tunneling between two structures when one structure already contains few photons. We demonstrate the possibility of both photon aided and inhibited tunneling of photons. The Bosonic nature of photons enhances the tunneling probability. We also show how the multiphoton tunneling probability can be either enhanced or inhibited due to the presence of photons. We find similar results for the higher order tunneling. Finally, we show that the presence of a squeezed field changes the nature of tunneling considerably.

  11. An Entropic Formulation of Tunneling Time

    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...

  12. Iterated splitting and the Tunnel Classification Conjecture

    Cho, Sangbum

    2011-01-01

    For a genus-1 1-bridge knot in the 3-sphere, that is, a (1,1)-knot, a middle tunnel is a tunnel that is not an upper or lower tunnel for some (1,1)-position. Most torus knots have a middle tunnel, and non-torus-knot examples were obtained by Goda, Hayashi, and Ishihara. In a previous paper, we generalized their construction and calculated the slope invariants for the resulting examples. We give an interated version of the construction that produces many more examples, and calculate their slope invariants. If one starts with the trivial knot, the iterated construction produces the 2-bridge knots, giving a new calculation of the slope invariants of their tunnels. Together with other information, the examples suggest a general classification conjecture for all tunnels of all tunnel number 1 knots.

  13. Heat Transfer in Underground Rail Tunnels

    Sadokierski, Stefan

    2007-01-01

    The transfer of heat between the air and surrounding soil in underground tunnels ins investigated, as part of the analysis of environmental conditions in underground rail systems. Using standard turbulent modelling assumptions, flow profiles are obtained in both open tunnels and in the annulus between a tunnel wall and a moving train, from which the heat transfer coefficient between the air and tunnel wall is computed. The radial conduction of heat through the surrounding soil resulting from changes in the temperature of air in the tunnel are determined. An impulse change and an oscillating tunnel air temperature are considered separately. The correlations between fluctuations in heat transfer coefficient and air temperature are found to increase the mean soil temperature. Finally, a model for the coupled evolution of the air and surrounding soil temperature along a tunnel of finite length is given.

  14. Resonant tunnel magnetoresistance in a double magnetic tunnel junction

    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.

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

    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.

  16. Acute pancreatitis

    Al Mofleh Ibrahim

    1997-01-01

    Full Text Available The past few years have witnessed a tremendous progress in our knowledge regarding the pathogenesis, diagnosis, prognostic evaluation and classification of acute pancreatitis. The role of ischemia, lysosomal enzymes, oxygen free radicals, polymorphnuclear cells-byproducts and inflammatory mediators in the pathogenesis of pancreatic necrosis and multiple organ failure has been emphasized. Furthermore, the recent knowledge about agents infecting pancreatic necrosis, routes of infection, bacteriological examination of fine needle aspirate and appropriate antibiotics have changed the concept of acute pancreatitis. New diagnostic tests such as rapid urinary trypsinogen-2 test and inflammatory mediators including polymorphnuclear elastase, C-reactive protein and interleukin-6 contribute to early diagnosis, prognostic evaluation and initiation of an appropriate therapy.

  17. Fermion tunneling from dynamical horizons

    Di Criscienzo, R.; Vanzo, L.

    2008-06-01

    The instability against emission of fermionic particles by the trapping horizon of an evolving black hole is analyzed and confirmed using the Hamilton-Jacobi tunneling method. This method automatically selects one special expression for the surface gravity of a changing horizon. The results also apply to point masses embedded in an expanding universe. As a bonus of the tunneling method, we gain the insight that the surface gravity still defines a temperature parameter as long as the evolution is sufficiently slow that the black-hole pass through a sequence of quasi-equilibrium states, and that black holes should be semi-classically unstable even in a hypothetical world without bosonic fields.

  18. Tunneling of a coupled system

    We consider tunneling through a potential barrier V(x) in the presence of a coupling term W(x,y). Let H(y) be the internal Hamiltonian associated with the coordinate y and let E0(x) be the ground state energy of the operator H(x;y) = H(y) + W(x,y) in which x is a parameter. Our result for the tunneling probability (in the WKB approximation) is P = exp(2i ∫ k0(x)dx) where, at energy E, k0(x) = [E-E0(x)-V(x)]sup(1/2)/(h/2π) is the local wave number in the presence of coupling. (orig.)

  19. Wildlife Tunnel Enhances Population Viability

    Michael McCarthy

    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.

  20. Seismic scanning tunneling macroscope - Theory

    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.

  1. Single-contact tunneling thermometry

    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.

  2. Selected elevation in quantum tunneling

    Granot, E

    2001-01-01

    The tunneling through an opaque barrier with a strong oscillating component is investigated. It is shown, that in the strong perturbations regime (in contrast to the weak one), higher perturbations rate does not necessarily improve the activation. In fact, in this regime two rival factors play a role, and as a consequence, this tunneling system behaves like a sensitive frequency-shifter device: for most incident particles' energies activation occurs and the particles are energetically elevated, while for specific energies activation is depressed and the transmission is very low. This effect is unique to the strong perturbation regime, and it is totally absent in the weak perturbation case. Moreover, it cannot be deduced even in the adiabatic regime. It is conjectured that this mechanism can be used as a frequency-dependent transistor, in which the device's transmission is governed by the external field frequency.

  3. Tunneling decay of false kinks

    Dupuis, Éric; MacKenzie, Richard; Marleau, Luc; Paranjape, M B; Ung, Y

    2015-01-01

    We consider the decay of "false kinks," that is, kinks formed in a scalar field theory with a pair of degenerate symmetry-breaking false vacua in 1+1 dimensions. The true vacuum is symmetric. A second scalar field and a peculiar potential are added in order for the kink to be classically stable. We find an expression for the decay rate of a false kink. As with any tunneling event, the rate is proportional to $\\exp(-S_E)$ where $S_E$ is the Euclidean action of the bounce describing the tunneling event. This factor varies wildly depending on the parameters of the model. Of interest is the fact that for certain parameters $S_E$ can get arbitrarily small, implying that the kink is only barely stable. Thus, while the false vacuum itself may be very long-lived, the presence of kinks can give rise to rapid vacuum decay.

  4. Observing remnants by fermions' tunneling

    Chen, Deyou; Wu, Houwen; Yang, Haitang

    2013-01-01

    The standard Hawking formula predicts the complete evaporation of black holes. In this paper, we introduce effects of quantum gravity into fermions' tunneling from Reissner-Nordstrom and Kerr black holes. The quantum gravity effects slow down the increase of Hawking temperatures. This property naturally leads to a residue mass in black hole evaporation. The corrected temperatures are affected by the quantum numbers of emitted fermions. Meanwhile, the temperature of the Kerr black hole is a fu...

  5. Laser tunneling from aligned molecules

    Smeenk, C T L; Sokolov, A V; Spanner, M; Lee, K F; Staudte, A; Villeneuve, D M; Corkum, P B

    2013-01-01

    We study multi-photon ionization from N_2, O_2 and benzene using circularly polarized light. By examining molecular frame photo-electron angular distributions, we illustrate how multi-photon ionization acts a momentum-selective probe of the local electron density in the Dyson orbitals for these molecules. We find good agreement with calculations based on a tunneling model and including saturation effects.

  6. Tunnel magnetoresistance of polymeric chains

    Walczak, Kamil

    2004-01-01

    Coherent spin-dependent electronic transport is investigated in a molecular junction made of polymeric chain attached to ferromagnetic electrodes (Ni and Co, respectively). Molecular system is described by a simple Huckel model, while the coupling to the electrodes is treated through the use of a broad-band theory. The current flowing through the device is calculated within non-equilibrium Green's function approach. It is shown that tunnel magnetoresistance of molecular junction can be quite ...

  7. Dissipative Effect and Tunneling Time

    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.

  8. Quantum tunneling and trace anomaly

    We compute the corrections, using the tunneling formalism based on a quantum WKB approach, to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. The results are related to the trace anomaly and are shown to be equivalent to findings inferred from Hawking's original calculation based on path integrals using zeta function regularization. Finally, exploiting the corrected temperature and periodicity arguments we also find the modification to the original Schwarzschild metric which captures the effect of quantum corrections.

  9. Quantum Tunneling Beyond Semiclassical Approximation

    Banerjee, Rabin; Majhi, Bibhas Ranjan

    2008-01-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black h...

  10. Variable Density Turbulence Tunnel Facility

    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...

  11. Tunneling beyond the Fermilab site

    An accelerator that crosses the Fermilab site boundary must have a minimum effect on the surrounding environment and the people residing in the area. Unobstructed public access should be allowed above the ring except in relatively few areas such as the injection, dump, and experimental regions. The accelerator should be a benign and unobtrusive neighbor not only when it is completed but also in the construction period. For these reasons underground tunneling for all or most of the ring seems attractive. In this note we look into some questions raised by tunneling beyond the Fermilab site. Most of our discussion is of general applicability. However, we will use as examples two specific ring configurations. The examples have not been optimized from the point of view of physics output or accelerator technology but are just specific examples which allow us to study questions of tunneling. One is a ring of 5 km radius (5 TeV) tangent to the Tevatron and entirely east of the Fox River and fed by a beam from the Tevatron which crosses under the river. We assume that each of these machines will have 100 beam fills per year and we scale the maximum intensities with the accelerator radii. Thus we assume that there will be 1.0 E14 protons in each beam of the 20 TeV machine and 2.5 E13 for the 5 TeV machine

  12. Confocal Annular Josephson Tunnel Junctions

    Monaco, Roberto

    2016-04-01

    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.

  13. Confocal Annular Josephson Tunnel Junctions

    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.

  14. Autonomous Robotic Inspection in Tunnels

    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.

  15. Tunneling decay of false vortices

    Lee, Bum-Hoon; MacKenzie, Richard; Paranjape, M B; Yajnik, U A; Yeom, Dong-han

    2013-01-01

    We consider the decay of vortices trapped in the false vacuum of a theory of scalar electrodynamics in 2+1 dimensions. The potential is inspired by models with intermediate symmetry breaking to a metastable vacuum that completely breaks a U(1) symmetry, while in the true vacuum the symmetry is unbroken. The false vacuum is unstable through the formation of true vacuum bubbles; however, the rate of decay can be extremely long. On the other hand, the false vacuum can contain metastable vortex solutions. These vortices contain the true vacuum inside in addition to a unit of magnetic flux and the appropriate topologically nontrivial false vacuum outside. We numerically establish the existence of vortex solutions which are classically stable; however, they can decay via tunneling. In general terms, they tunnel to a configuration which is a large, thin-walled vortex configuration that is now classically unstable to the expansion of its radius. We compute an estimate for the tunneling amplitude in the semi-classical...

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

    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

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

    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.

  18. Tunnel widening in anterior cruciate ligament reconstruction

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

    1999-01-01

    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 and...... similar endoscopic procedure and accelerated postoperative rehabilitation. Tunnel widening was determined using standardized anteroposterior (AP) and lateral X-rays adjusted for magnification. A limited series of MRIs was performed to validate these measurements. There was a significant difference in the...... degree of tunnel widening between the two groups. The mean increase in femoral tunnel area in the hamstring group was 100.4% compared with a decrease of 25% in the patella tendon group (P = <0.0001). In the tibial tunnel the mean increase in the hamstring group was 73.9% compared with a decrease of 2...

  19. Micromachined Tunneling Displacement Transducers for Physical Sensors

    Kenny, T. W.; Kaiser, W. J.; Podosek, J. A.; Rockstad, H. K.; Reynolds, J. K.; Vote, E. C.

    1993-01-01

    We have designed and constructed a series of tunneling sensors which take advantage of the extreme position sensitivity of electron tunneling. In these sensors, a tunneling displacement transducer, based on scanning tunneling microscopy principles, is used to detect the signal-induced motion of a sensor element. Through the use of high-resonant frequency mechanical elements for the transducer, sensors may be constructed which offer wide bandwidth, and are robust and easily operated. Silicon micromachining may be used to fabricate the transducer elements, allowing integration of sensor and control electronics. Examples of tunneling accelerometers and infrared detectors will be discussed. In each case, the use of the tunneling transducer allows miniaturization of the sensor as well as enhancement of the sensor performance.

  20. Tunnel design considering stress release effect

    Van-hung DAO

    2009-09-01

    Full Text Available 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 0.086 5 m to 0.091 9 m occurrs, we can install supporting structures that satisfy the stability and economical requirements.

  1. Investigation into scanning tunnelling luminescence microscopy

    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. Acute abdomen

    Acute abdomen may be connected with the injury of one of the internal organs, injury of large blood vessels, with the spreading of pains from some other area. It may also be a manifestation of systemic disease or poisoning. The main purposes of radiodiagnosis are: determination of the cause of clinical syndrome; determination of the localization and spreading of pathological changes in abdominal organs; finding out the character of complications. If the data of the ordinary roentgenological investiagtion and isn't complete, the computer tomography of abdominal and pelvic cavities is needed

  3. Emissions of noxious supstances in road tunnel

    Kenda, Ivan

    2008-01-01

    Construction of tunnels, galleries, bridging objects and other underground engineers constructions is the most exacting work at low buildings. Tunnel seems to be very simple building but there must be interdisciplinary interweaving of entire civil engineering knowledge of geology, mining, architectures, ecology and of other in all phases of planning, building and maintenance of underground constructions. Tunnel is only one of the objects on a road. Careful planning of traffic only throu...

  4. Quantum tunneling and field electron emission theories

    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

  5. Carpal tunnel syndrome caused by cysticercosis

    Sharma S; Sharma Nalini; Yeolekar M

    2010-01-01

    We present a case of carpal tunnel syndrome (CTS) due to compression of the median nerve within the carpal tunnel, caused by cysticercosis. Nerve conduction studies revealed severe CTS. Magnetic resonance imaging suggested an inflammatory mass compressing the median nerve in carpal tunnel. The histological diagnosis was consistent with cysticercosis. The case resolved with conservative treatment. Such solitary presentation of entrapment median neuropathy as CTS caused by cysticercosis is extr...

  6. Radio-frequency scanning tunnelling microscopy

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

    2007-01-01

    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 diminishe...

  7. Tunnel magnetoresistance and interfacial electronic state

    Inoue, J; Itoh, H.

    2002-01-01

    We study the relation between tunnel magnetoresistance (TMR) and interfacial electronic states modified by magnetic impurities introduced at the interface of the ferromagnetic tunnel junctions, by making use of the periodic Anderson model and the linear response theory. It is indicated that the TMR ratio is strongly reduced depending on the position of the $d$-levels of impurities, based on reduction in the spin-dependent $s$-electron tunneling in the majority spin state. The results are comp...

  8. Tunnel Probabilistic Structural Analysis Using the FORM

    Yousef Mirzaeian; Kourosh Shahriar; Mostafa Sharifzadeh

    2015-01-01

    In this paper tunnel probabilistic structural analysis (TuPSA) was performed using the first order reliability method (FORM). In TuPSA, a tunnel performance function is defined according to the boundary between the structural stability and instability. Then the performance function is transformed from original space into the standard normal variable space to obtain the design point, reliability index, and also the probability of tunnel failure. In this method, it is possible to consider the d...

  9. Unconventional scanning tunneling conductance spectra for graphene

    Saha, K.; Paul, I.; Sengupta, K.

    2009-01-01

    We compute the tunneling conductance of graphene as measured by a scanning tunneling microscope (STM) with a normal/superconducting tip. We demonstrate that for undoped graphene with zero Fermi energy, the first derivative of the tunneling conductance with respect to the applied voltage is proportional to the density of states of the STM tip. We also show that the shape of the STM spectra for graphene doped with impurities depends qualitatively on the position of the impurity atom in the grap...

  10. Theory of tunneling transport in periodic chains

    Prodan, Emil; Car, Roberto

    2009-01-01

    We present an extended discussion of a recently proposed theoretical approach for off-resonance tunneling transport. The proofs and the arguments are explained at length and simple analogies and illustrations are used where possible. The result is an analytic formula for the asymptotic tunneling conductance which involves the overlap of three well defined physical quantities. We argue that the formula can be used to gain fresh insight into the tunneling transport characteristics of various sy...

  11. Time Correlation in Tunneling of Photons

    Hrasko, Peter

    2000-01-01

    I propose to consider photon tunneling as a space-time correlation phenomenon between the emission and absorption of a photon on the two sides of a barrier. Standard technics based on an appropriate counting rate formula may then be applied to derive the tunneling time distribution without any {\\em ad hoc} definition of this quantity. General formulae are worked out for a potential model using Wigner-Weisskopf method. For a homogeneous square barrier in the limit of zero tunneling probability...

  12. Air pollution measurements in traffic tunnels.

    De Fré, R; Bruynseraede, P; Kretzschmar, J G

    1994-01-01

    Air pollution measurements during April 1991 are reported from the Craeybeckx highway tunnel in Antwerp, Belgium. The tunnel was used daily by an average of 45,000 vehicles, of which 60% were gasoline fueled passenger cars, 20% diesel cars, and 20% trucks. Of the gasoline cars, only 3% had three-way catalysts. Tunnel air concentrations of nitrogen oxides, sulphur dioxide, carbon dioxide, carbon monoxide, nonmethane hydrocarbons, volatile organic compounds, polycyclic aromatic hydrocarbons, an...

  13. Resonant Tunneling in the Quantum Hydrodynamic Model

    Carl L. Gardner

    1995-01-01

    The phenomenon of resonant tunneling is simulated and analyzed in the quantum hydrodynamic (QHD) model for semiconductor devices. Simulations of a parabolic well resonant tunneling diode at 77 K are presented which show multiple regions of negative differential resistance (NDR) in the current-voltage curve. These are the first simulations of the QHD equations to show multiple regions of NDR.Resonant tunneling (and NDR) depend on the quantum interference of electron wavefunctions and therefore...

  14. Climatic wind tunnel for wind engineering tasks

    Kuznetsov, Sergeii; Pospíšil, Stanislav; Král, Radomil

    2015-01-01

    Roč. 112, 2-B (2015), s. 303-316. ISSN 1897-628X R&D Projects: GA ČR(CZ) GA14-12892S Keywords : climatic tunnel * wind tunnel * atmospheric boundary layer * flow resistance * wind tunnel contraction Subject RIV: JM - Building Engineering https://suw.biblos.pk.edu.pl/resources/i5/i6/i6/i7/i6/r56676/KuznetsovS_ClimaticWind.pdf

  15. Wind-Tunnel/Flight Correlation, 1981

    Mckinney, L. W. (Editor); Baals, D. D. (Editor)

    1982-01-01

    Wind-tunnel/flight correlation activities are reviewed to assure maximum effectiveness of the early experimental programs of the National Transonic Facility (NTF). Topics included a status report of the NTF, the role of tunnel-to-tunnel correlation, a review of past flight correlation research and the resulting data base, the correlation potential of future flight vehicles, and an assessment of the role of computational fluid dynamics.

  16. Joberget tunnel - Analysis of stability and support design for tunneling in soil

    Langåker, Margrete Oie

    2014-01-01

    The Norwegian Public Roads Administration (NPRA) is planning a construction of a new road tunnel, Joberget tunnel in the Granvin Municipality of western Norway. Approximately 80 m from the southwestern entrance of the tunnel will be excavated, partly in soil and partly in rock. Soil tunneling will be performed in this section instead of excavation of large open cuts, to avoid difficult work conditions, landslide hazards and severe landscape interventions. Sweco Norge AS in cooperation with th...

  17. Femtosecond tunneling response of surface plasmon polaritons

    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 and...... suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...

  18. Palladium electrodes for molecular tunnel junctions.

    Chang, Shuai; Sen, Suman; Zhang, Peiming; Gyarfas, Brett; Ashcroft, Brian; Lefkowitz, Steven; Peng, Hongbo; Lindsay, Stuart

    2012-10-26

    Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with complementary metal-oxide-semiconductor fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions that we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More than 75% of all the recorded signal peaks indicate the base correctly. PMID:23037952

  19. Palladium electrodes for molecular tunnel junctions

    Gold has been the metal of choice for research on molecular tunneling junctions, but it is incompatible with complementary metal–oxide–semiconductor fabrication because it forms deep level traps in silicon. Palladium electrodes do not contaminate silicon, and also give higher tunnel current signals in the molecular tunnel junctions that we have studied. The result is cleaner signals in a recognition-tunneling junction that recognizes the four natural DNA bases as well as 5-methyl cytosine, with no spurious background signals. More than 75% of all the recorded signal peaks indicate the base correctly. (paper)

  20. Tunneling Ionization Time Resolved by Backpropagation

    Ni, Hongcheng; Saalmann, Ulf; Rost, Jan-Michael

    2016-07-01

    We determine the ionization time in tunneling ionization by an elliptically polarized light pulse relative to its maximum. This is achieved by a full quantum propagation of the electron wave function forward in time, followed by a classical backpropagation to identify tunneling parameters, in particular, the fraction of electrons that has tunneled out. We find that the ionization time is close to zero for single active electrons in helium and in hydrogen if the fraction of tunneled electrons is large. We expect our analysis to be essential to quantify ionization times for correlated electron motion.

  1. Tunneling with dissipation in open quantum systems

    Based on the general form of the master equation for open quantum systems the tunneling is considered. Using the path integral technique a simple closed form expression for the tunneling rate through a parabolic barrier is obtained. The tunneling in the open quantum systems strongly depends on the coupling with environment. We found the cases when the dissipation prohibits tunneling through the barrier but decreases the crossing of the barrier for the energies above the barrier. As a particular application, the case of decay from the metastable state is considered

  2. Construction begins on LHC transfer tunnel

    Laurent Guiraud

    1999-01-01

    Engineers begin work on one of the transfer tunnels that will provide pre-accelerated proton beams from the SPS to the LHC, CERN's new particle accelerator. While this work is being done, beams are still being accelerated in the current LEP accelerator to study as much of the outer reaches of physics as it can before closure in 2000 to make way for the LHC. Because of this, the tunnel is being built from an access shaft towards the smaller SPS pre-accelerator before the tunnel is extended to the large soon-to-be LHC tunnel.

  3. Electronic tunneling currents at optical frequencies

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1975-01-01

    Rectification characteristics of nonsuperconducting metal-barrier-metal junctions as deduced from electronic tunneling theory have been observed experimentally for optical frequency irradiation of the junction.

  4. [Acute myocarditis].

    Combes, Alain

    2013-05-01

    Myocarditis is defined as inflammation of the myocardium accompanied by myocellular necrosis. Acute myocarditis must be considered in patients who present with recent onset of cardiac failure or arrhythmia. Fulminant myocarditis is a distinct entity characterized by sudden onset of severe congestive heart failure or cardiogenic shock, usually following a flu-like illness, parvovirus B19, human herpesvirus 6, coxsackievirus and adenovirus being the most frequently viruses responsible for the disease. Treatment of myocarditis remains largely supportive, since immunosuppression has not been proven to be beneficial for acute lymphocytic myocarditis. Trials of antiviral therapies, or immunostimulants such as interferons, suggest a potential therapeutic role but require further investigation. Lastly, early recognition of patients rapidly progressing to refractory cardiac failure and their immediate transfer to a medical-surgical center experienced in mechanical circulatory support is warranted. In this setting, ECMO should be the first-line mechanical assistance. For highly unstable patients, a Mobile Cardiac Assistance Unit, that rapidly travels to primary care hospitals with a portable ECMO system and hooks it up before refractory multiorgan failure takes hold, is the preferred option. PMID:23789482

  5. Tunneling into high-Tc superconductors: methods of fabricating tunnel junctions

    In the preprint we shell review some experimental results on electron tunneling into high-Tc superconductors. Pros and cons of various methods of fabricating the tunnel junctions with metal oxide compound as a base electrode are discussed. The data obtained by different groups are examined in terms of the tunneling criterion. 66 refs.; 13 figs

  6. RECURRENT SEASONAL ACUTE PSYCHOSIS

    Agarwal, Vivek

    1999-01-01

    Acute psychoses have been reported to occur more frequently in summer. This is a report of seasonal recurrence of acute psychosis in a patient. This case report emphasizes towards the biological etiology of acute psychoses.

  7. Acute cerebellar ataxia

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

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

    Aims of the present paper are: i) presenting and analysing the results of various numerical calculations on the penetration and return times Pen>, Ret>, during tunnelling inside a rectangular potential barrier, for various penetration depths xf; ii) putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) DτT and DτR for the time durations of transmission and reflection processes; iii)mentioning, moreover, that our definition 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

  9. Giant electrode effect on tunnelling electroresistance in ferroelectric tunnel junctions.

    Soni, Rohit; Petraru, Adrian; Meuffels, Paul; Vavra, Ondrej; Ziegler, Martin; Kim, Seong Keun; Jeong, Doo Seok; Pertsev, Nikolay A; Kohlstedt, Hermann

    2014-01-01

    Among recently discovered ferroelectricity-related phenomena, the tunnelling electroresistance (TER) effect in ferroelectric tunnel junctions (FTJs) has been attracting rapidly increasing attention owing to the emerging possibilities of non-volatile memory, logic and neuromorphic computing applications of these quantum nanostructures. Despite recent advances in experimental and theoretical studies of FTJs, many questions concerning their electrical behaviour still remain open. In particular, the role of ferroelectric/electrode interfaces and the separation of the ferroelectric-driven TER effect from electrochemical ('redox'-based) resistance-switching effects have to be clarified. Here we report the results of a comprehensive study of epitaxial junctions comprising BaTiO(3) barrier, La(0.7)Sr(0.3)MnO(3) bottom electrode and Au or Cu top electrodes. Our results demonstrate a giant electrode effect on the TER of these asymmetric FTJs. The revealed phenomena are attributed to the microscopic interfacial effect of ferroelectric origin, which is supported by the observation of redox-based resistance switching at much higher voltages. PMID:25399545

  10. Quantum tunnelling in condensed media

    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

  11. Quantum Tunneling Beyond Semiclassical Approximation

    Banerjee, Rabin

    2008-01-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  12. Quantum tunneling beyond semiclassical approximation

    Banerjee, Rabin; Ranjan Majhi, Bibhas

    2008-06-01

    Hawking radiation as tunneling by Hamilton-Jacobi method beyond semiclassical approximation is analysed. We compute all quantum corrections in the single particle action revealing that these are proportional to the usual semiclassical contribution. We show that a simple choice of the proportionality constants reproduces the one loop back reaction effect in the spacetime, found by conformal field theory methods, which modifies the Hawking temperature of the black hole. Using the law of black hole mechanics we give the corrections to the Bekenstein-Hawking area law following from the modified Hawking temperature. Some examples are explicitly worked out.

  13. Fermion Tunneling Beyond Semiclassical Approximation

    Majhi, Bibhas Ranjan

    2008-01-01

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in \\cite{Majhi3} for the scalar particle, Hawking radiation as tunneling of Dirac particle through an event horizon is analysed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  14. Fermion tunneling beyond semiclassical approximation

    Majhi, Bibhas Ranjan

    2009-02-01

    Applying the Hamilton-Jacobi method beyond the semiclassical approximation prescribed in R. Banerjee and B. R. Majhi, J. High Energy Phys.JHEPFG1029-8479 06 (2008) 09510.1088/1126-6708/2008/06/095 for the scalar particle, Hawking radiation as tunneling of the Dirac particle through an event horizon is analyzed. We show that, as before, all quantum corrections in the single particle action are proportional to the usual semiclassical contribution. We also compute the modifications to the Hawking temperature and Bekenstein-Hawking entropy for the Schwarzschild black hole. Finally, the coefficient of the logarithmic correction to entropy is shown to be related with the trace anomaly.

  15. Tunneling without barriers with gravity

    Kanno, Sugumi; Sasaki, Misao; 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 c...

  16. Chemically driven electron tunnelling pumps

    Goychuk, I

    2006-01-01

    The simplest mechanism for molecular electron pumps is discussed which is based on nonadiabatic electron tunnelling and nonequilibrium conformational fluctuations. Such fluctuations can be induced, e.g. by random binding of negatively charged ATP molecules to the electron-transferring molecular complex, their subsequent hydrolysis and the products dissociation. The pumping rate can be controlled by the ATP concentration in solution. Depending on the model parameters there may exist a critical ATP concentration for the pump to function. Alternatively, nonequilibrium fluctuations can be induced by externally applied stochastic electric fields. For realistically chosen parameters, the mechanism is shown to be robust and highly efficient.

  17. Acute Myopericarditis Mimicking Acute Myocardial Infarction

    Seval İzdeş; Neriman Defne Altıntaş; Gülin Karaaslan; Recep Uygun; Abdulkadir But

    2011-01-01

    Acute coronary syndromes among young adults are relatively low when compared with older population in the intensive care unit. Electrocardiographic abnormalities mimicking acute coronary syndromes may be caused by non-coronary syndromes and the differential diagnosis requires a detailed evaluation. We are reporting a case of myopericarditis presenting with acute ST elevation and elevated cardiac enzymes simulating acute coronary syndrome. In this case report, the literature is reviewed to dis...

  18. Spin-polarized Inelastic Electron Tunneling Spectroscopy of Molecular Magnetic Tunnel Junctions

    In this study, we fabricate molecular magnetic tunnel junctions and demonstrate that inelastic electron tunneling spectroscopy technique can be utilized to inspect such junctions to investigate the existence of desired molecular species in the device area. Tunneling magnetoresistance measurements have been carried out and spin-dependent tunneling transport has been observed. Bias-dependence of the tunneling resistance has also been detected. IETS measurements at different magnetic field suggested that the TMR bias-dependence was likely caused by the inelastic scattering due to the molecular vibrations

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

    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...

  20. Transport of dangerous goods through road tunnels

    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...

  1. Road tunnels safety according to European legislation

    Fedor KÁLLAY

    2008-01-01

    Full Text Available The article deals with safety of European road tunnels in accordance with actual European legislation. Standards and recommendations of European Commission, PIARC and other professional bodies of the European Union define minimal technological requirements for equipment and operation of the tunnels in scope of Trans-European Road Network.

  2. Flow-Based Detection of DNS Tunnels

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

    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

  3. 75 FR 42643 - National Tunnel Inspection Standards

    2010-07-22

    ... Advance Notice of Proposed Rulemaking (ANPRM) The FHWA issued an ANPRM on November 18, 2008, at 73 FR... vulnerability to the tunnel operating environment and mean time to failure. The ACEC commented that inspection... Federal Highway Administration 23 CFR Part 650 RIN 2125-AF24 National Tunnel Inspection Standards...

  4. Superconducting Super Collider Laboratory : tunnel boring

    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.

  5. Hawking temperature and higher order tunnelling calculations

    Chatterjee, Bhramar

    2009-01-01

    Hawking radiation has recently been explained in terms of tunnelling across the black hole horizon in a Hamilton-Jacobi framework. Higher order calculations using both usual and non-singular coordinates are found to change the tunnelling amplitude, but this change is not a simple alteration of the Hawking temperature.

  6. A Supermagnetic Tunnel Full of Subatomic Action

    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.

  7. Chronic Synovitis after Open Carpal Tunnel Decompression.

    Yousef, Justin; Chan, Patrick; Rahdon, Richard

    2016-06-01

    Open carpal tunnel decompression is a common procedure with potential long-term complications such as scar tenderness, pillar pain and neuroma. We present the case of a 65 year-old male with chronic lipomatous hypertrophy of the wrist and chronic flexor tenosynovitis after open carpal tunnel release for its rarity and severity of symptoms that required further surgery. PMID:27454645

  8. 49 CFR 177.810 - Vehicular tunnels.

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vehicular tunnels. 177.810 Section 177.810 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY... Information and Regulations § 177.810 Vehicular tunnels. Except as regards Class 7 (radioactive)...

  9. Scanning tunneling microscopy of dye thin films

    The Rhodamine 6G films on a metal and a semiconductor substrates were studied by scanning tunneling microscopy and spectral ellipsometry techniques. Scanning tunneling microscopy of dye on a metal substrate allowed obtaining interlayer surface profile with atomic spatial resolution 0.08 nm

  10. Flow-based detection of DNS tunnels

    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

  11. Tunnel number one, genus one fibered knots

    Baker, Kenneth L.; Johnson, Jesse E.; Klodginski, Elizabeth A.

    2006-01-01

    We determine the genus one fibered knots in lens spaces that have tunnel number one. We also show that every tunnel number one, once-punctured torus bundle is the result of Dehn filling a component of the Whitehead link in the 3-sphere.

  12. Flapping around in a wind tunnel

    Dimitriadis, Grigorios

    2015-01-01

    Aerodynamic investigations of animal flight have usually concentrated on static conditions. These are good enough to analyse gliding flight but not other types of flight, such as cruise (migrations), take-off and landing or manoeuvres. In this work we present wind tunnel experiments on geese flying in a wind tunnel and unsteady aerodynamic simulations of these flights, based on the Vortex Lattice Method.

  13. Ac electronic tunneling at optical frequencies

    Faris, S. M.; Fan, B.; Gustafson, T. K.

    1974-01-01

    Rectification characteristics of non-superconducting metal-barrier-metal junctions deduced from electronic tunneling have been observed experimentally for optical frequency irradiation of the junction. The results provide verification of optical frequency Fermi level modulation and electronic tunneling current modulation.

  14. Gauge independence of tunneling rates

    Plascencia, Alexis D

    2015-01-01

    Despite the gauge dependence of the effective action at zero and finite temperature, it is shown that it leads to tunneling and nucleation rates that remain independent of the choice of gauge-fixing. Taking as a starting point the path integral that defines the transition amplitude from a false vacuum to itself, a careful treatment of the boundary conditions and the gauge-fixing allows to show that decay rates are exactly determined by the effective action evaluated at a generalized bounce configuration. The latter is a solution to the quantum equations of motion, with boundary conditions fixed by the false vacuum. The resulting tunneling rate is gauge-independent, as the Nielsen identities imply that the explicit gauge dependence in the effective action is exactly cancelled by the gauge dependence of the solution. This holds for any election of gauge-fixing that leads to an invertible Faddeev-Popov matrix. The result is nonperturbative and model-independent, and also clarifies how to incorporate radiative co...

  15. Critical issues concerning tunnel ventilation in the super conducting super collider ring tunnel

    In this paper, the author discusses the problem of designing a ventilation system for the SSC Collider Ring Tunnel. The history of ventilation of tunnels is briefly reviewed and the types of systems used for ventilation of rail, transit and highway tunnels are described in detail. Next, the ventilation system prepared for the Collider Ring Tunnel in the RTK conceptual conventional design report is described. The author questions this design from a safety and practical standpoint. He offers several other solutions which provided a more powerful system for emergencies. One supplies fresh outside air uniformly along the tunnel length. All suggested systems increase costs over the RTK proposed system. The possible problem of troublesome condensation forming on equipment in the tunnel and tunnel walls in hot, humid weather is also a major concern. 5 figs

  16. Characterization of magnetic tunnel junction test pads

    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...... 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....

  17. Snow and ice blocking of tunnels

    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.

  18. Therapy of tarsal arthritis in cow

    Toholj Bojan

    2014-01-01

    Full Text Available With mastitis and reproductive disorders, musculoskeletal diseases represent one of the most important problems in modern cattle production. In this paper we described the diagnostic procedure and the possibility of treatment of septic arthritis in cattle. After a successful general clinical examination, ultrasound diagnostics and arthrocenthesis of affected joint are done. After ultrasound examination and trail puncture of the joint are done, we conducted therapy which was consisting of local and systemic treatments. By conducted therapy there was a significant improvement in the health of the animal. The swelling is completely evaporated and lameness was less pronounced, and it is progressively reduced in the future. [Projekat Ministarstva nauke Republike Srbije, br. TR 31062

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

    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. PMID:21029142

  20. Acute abdomen

    The book first presents the anatomy and physiology of the abdomen and continues with chapters discussing clinical and laboratory aspects and a suitable order of diagnostic examinations with reference to the acute processes, explaining the diagnostic tools: ultrasonography, radiography including angiography and CT, tapping techniques and endoscopy together with their basic principles, examination techniques, and diagnosis. One chapter presents a complete survey of the processes involving the entire abdomen - as e.g. peritonitis, ileus, abdominal trauma, intraperitoneal hemorrage. This chapter profoundly discusses the diagnostics and therapies including emergency measures and surgery. Problems requiring consultation among varous specialists, in internal medicine, gynecology, urology, or pediatrics, are discussed in great detail. Information for the anesthetist is given for cases of emergency. More than one third of the book is devoted to organ-specific information, dicussing the pathogenesis, diagnostics, and therapy of the oesophagus, stomach, large and small intestine, bile ducts, pankreas, liver, spleen, and the abdominal vessels and the abdominal wall. (orig.) With 153 figs., 90 tabs

  1. Acute pancreatitis

    A prospective study was performed on the relationship of CT findings to the clinical course of 148 patients with acute pancreatitis. The type of pancreatic inflammation seen on CT was classified into six categories based on an overall assessment of size, contour and density of the gland, and peripancreatic abnormalities. The majority (94%) of patients in whom CT showed mild pancreatic changes (grades A, B and C) had two or less positive clinical indicaters of severe pancreatitis (Ranson's signs). In contrast, 92% of patients in whom CT showed more severe changes of pancreatitis (grades D, E or F) had three or more positive signs. The nine patients who died with pancreatitis-related complications were in grades D, E or F. We wish to draw attention to a CT appearance which we have called 'fat islets' (low density intrapancreatic or peripancreatic areas, the contents of which approach fat in attenuation values); there was a strong correlation between this appearance and subsequent infection. (author). 24 refs.; 7 figs.; 4 tabs

  2. Simulation of Stress Distribution around Tunnels and Interaction between Tunnels Using an Elasto-plastic Model

    Muya M S; He Bo; Wang Jingtao; Li Guocheng

    2007-01-01

    This article presents a computer simulation of stress distribution around tunnels and interaction between tunnels using an elasto-plastic model. A finite element method using ANSYS software has been used for the analyses of one and two tunnels at different overburden depths with different separating distances between the tunnels. The results of numerical analyses indicate that stress distribution and stress concentration around the tunnels vary with the overburden depths. It is found that the coefficients of stress concentration for elasto-plastic medium are smaller than those for elastic one by 1.9%. Furthermore, the interaction between the two tunnels rapidly decreases with the increase of separation distance between them. In addition, for quantitatively describing the interaction between the two tunnels, a critical separation distance is introduced. The critical separation distances between the two tunnels at different overburden depths are 8 m, 12 m, and 14 m respectively. This fact is very important and essential for the design of mining tunnels and to ensure safety in tunnel engineering.

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

    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. PMID:21608024

  4. Giant tunneling magnetoresistance in silicene

    Wang, Yu, E-mail: ywang@semi.ac.cn [Department of Physics, Faculty of Science, Kunming University of Science and Technology, Kunming, 650500 Yunnan (China); Lou, Yiyi [Yiyuan Student Community, Center of Student Community Education and Management, Kunming University of Science and Technology, Kunming, 650500 Yunnan (China)

    2013-11-14

    We have theoretically studied ballistic electron transport in silicene under the manipulation of a pair of ferromagnetic gate. Transport properties like transmission and conductance have been calculated by the standard transfer matrix method for parallel and antiparallel magnetization configurations. It is demonstrated here that, due to the stray field-induced wave-vector filtering effect, remarkable difference in configuration-dependent transport gives rise to a giant tunneling magnetoresistance. In combination with the peculiar buckled structure of silicene and its electric tunable energy gap, the receiving magnetoresistance can be efficiently modulated by the externally-tunable stray field, electrostatic potential, and staggered sublattice potential, providing some flexible strategies to construct silicene-based nanoelectronic device.

  5. Tunnel effect wave energy detection

    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.

  6. Theory of dissociative tunneling ionization

    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...

  7. WT - WIND TUNNEL PERFORMANCE ANALYSIS

    Viterna, L. A.

    1994-01-01

    WT was developed to calculate fan rotor power requirements and output thrust for a closed loop wind tunnel. The program uses blade element theory to calculate aerodynamic forces along the blade using airfoil lift and drag characteristics at an appropriate blade aspect ratio. A tip loss model is also used which reduces the lift coefficient to zero for the outer three percent of the blade radius. The application of momentum theory is not used to determine the axial velocity at the rotor plane. Unlike a propeller, the wind tunnel rotor is prevented from producing an increase in velocity in the slipstream. Instead, velocities at the rotor plane are used as input. Other input for WT includes rotational speed, rotor geometry, and airfoil characteristics. Inputs for rotor blade geometry include blade radius, hub radius, number of blades, and pitch angle. Airfoil aerodynamic inputs include angle at zero lift coefficient, positive stall angle, drag coefficient at zero lift coefficient, and drag coefficient at stall. WT is written in APL2 using IBM's APL2 interpreter for IBM PC series and compatible computers running MS-DOS. WT requires a CGA or better color monitor for display. It also requires 640K of RAM and MS-DOS v3.1 or later for execution. Both an MS-DOS executable and the source code are provided on the distribution medium. The standard distribution medium for WT is a 5.25 inch 360K MS-DOS format diskette in PKZIP format. The utility to unarchive the files, PKUNZIP, is also included. WT was developed in 1991. APL2 and IBM PC are registered trademarks of International Business Machines Corporation. MS-DOS is a registered trademark of Microsoft Corporation. PKUNZIP is a registered trademark of PKWare, Inc.

  8. Simulation of people's evacuation in tunnel fire

    2006-01-01

    The simulation model Tunev(tunnel evacuation) was developed for people's evacuation in tunnel fire. It contains simple database of the people's behavioral reaction and structure characteristic parameters of tunnel fireproofing. The model can be used to calculate the total evacuation time in various scenes when fire occurs in the different locations of the tunnel. Combined with fire simulation soft ware CFD- POENICS3.5, Tunev model can be used to calculate the fire danger coming time; by comparing with these two kinds of time, it can be used to assess the safety of the evacuation, and the evacuation process also have a dynamic demo. The simulation results show that the Tunev model can be used to predict the reliability of safe evacuation for people in tunnel fire and provide references for people's safe escape scheme. Some relevant concepts of the model were described and an evacuation simulation of a typical tunnel case, i.e. Xuefeng Mountain Tunnel was performed by using this model. And the model's validation and actual application were also described.

  9. Rudolf Hermann, wind tunnels and aerodynamics

    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.

  10. Investigation into scanning tunnelling luminescence microscopy

    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 provide information on recombination processes and material properties. The design and construction of a scanning tunnelling luminescence microscope is described in detail. Operating under ambient conditions, the microscope has several novel features, including a new type of miniature inertial slider-based approach motor, large solid-angle light collection optical arrangement and a tip-height regulation system which requires the minimum of operator input. (author)

  11. Homoepitaxial graphene tunnel barriers for spin transport

    Friedman, Adam L.; van't Erve, Olaf M. J.; Robinson, Jeremy T.; Whitener, Keith E.; Jonker, Berend T.

    2016-05-01

    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.

  12. The Thames Tideway Tunnel (3/3)

    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.

  13. Thermal stability of tunneling spin polarization

    We present a study of the thermal stability of tunneling spin polarization in Al/AlOx/ferromagnet junctions based on the spin-polarized tunneling technique, in which the Zeeman-split superconducting density of states in the Al electrode is used as a detector for the spin polarization. Thermal robustness of the polarization, which is of key importance for the performance of magnetic tunnel junction devices, is demonstrated for post-deposition anneal temperatures up to 500oC with Co and Co90Fe10 top electrodes, independent of the presence of an FeMn layer on top of the ferromagnet

  14. Integrated tunneling sensor for nanoelectromechanical systems

    Sadewasser, S.; Abadal, G.; Barniol, N.; Dohn, Søren; Boisen, Anja

    2006-01-01

    Transducers based on quantum mechanical tunneling provide an extremely sensitive sensor principle, especially for nanoelectromechanical systems. For proper operation a gap between the electrodes of below 1 nm is essential, requiring the use of structures with a mobile electrode. At such small...... 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 on this...... analysis, a tunneling sensor is fabricated by Si micromachining technology and its proper operation is demonstrated. (c) 2006 American Institute of Physics....

  15. Scanning Tunneling Microscope For Use In Vacuum

    Abel, Phillip B.

    1993-01-01

    Scanning tunneling microscope with subangstrom resolution developed to study surface structures. Although instrument used in air, designed especially for use in vacuum. Scanning head is assembly of small, mostly rigid components made of low-outgassing materials. Includes coarse-positioning mechanical-translation stage, on which specimen mounted by use of standard mounting stub. Tunneling tip mounted on piezoelectric fine-positioning tube. Application of suitable voltages to electrodes on piezoelectric tube controls scan of tunneling tip across surface of specimen. Electronic subsystem generates scanning voltages and collects data.

  16. HYDRAULIC RESEARCH OF AERATORS ON TUNNEL SPILLWAYS

    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.

  17. Advancing Test Capabilities at NASA Wind Tunnels

    Bell, James

    2015-01-01

    NASA maintains twelve major wind tunnels at three field centers capable of providing flows at 0.1 M 10 and unit Reynolds numbers up to 45106m. The maintenance and enhancement of these facilities is handled through a unified management structure under NASAs Aeronautics and Evaluation and Test Capability (AETC) project. The AETC facilities are; the 11x11 transonic and 9x7 supersonic wind tunnels at NASA Ames; the 10x10 and 8x6 supersonic wind tunnels, 9x15 low speed tunnel, Icing Research Tunnel, and Propulsion Simulator Laboratory, all at NASA Glenn; and the National Transonic Facility, Transonic Dynamics Tunnel, LAL aerothermodynamics laboratory, 8 High Temperature Tunnel, and 14x22 low speed tunnel, all at NASA Langley. This presentation describes the primary AETC facilities and their current capabilities, as well as improvements which are planned over the next five years. These improvements fall into three categories. The first are operations and maintenance improvements designed to increase the efficiency and reliability of the wind tunnels. These include new (possibly composite) fan blades at several facilities, new temperature control systems, and new and much more capable facility data systems. The second category of improvements are facility capability advancements. These include significant improvements to optical access in wind tunnel test sections at Ames, improvements to test section acoustics at Glenn and Langley, the development of a Supercooled Large Droplet capability for icing research, and the development of an icing capability for large engine testing. The final category of improvements consists of test technology enhancements which provide value across multiple facilities. These include projects to increase balance accuracy, provide NIST-traceable calibration characterization for wind tunnels, and to advance optical instruments for Computational Fluid Dynamics (CFD) validation. Taken as a whole, these individual projects provide significant

  18. Application of Important Factors in Tunnel Projects

    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.

  19. Quantum limit in resonant vacuum tunneling transducers

    Onofrio, Roberto

    2010-01-01

    We propose an electromechanical transducer based on a resonant-tunneling configuration that, with respect to the standard tunneling transducers, allows larger tunneling currents while using the same bias voltage. The increased current leads to an increase of the shot noise and an increase of the momentum noise which determine the quantum limit in the system under monitoring. Experiments with micromachined masses at 4.2 K could show dominance of the momentum noise over the Brownian noise, allowing observation of the quantum-mechanical noise at the mesoscopic scale.

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

    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 < 0.05). As 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. PMID:23184493

  1. Room-temperature tunnel magnetoresistance and spin-polarized tunneling through an organic semiconductor barrier.

    Santos, T S; Lee, J S; Migdal, P; Lekshmi, I C; Satpati, B; Moodera, J S

    2007-01-01

    Electron spin-polarized tunneling is observed through an ultrathin layer of the molecular organic semiconductor tris(8-hydroxyquinolinato)aluminum (Alq3). Significant tunnel magnetoresistance (TMR) was measured in a Co/Al2O3/Alq3/NiFe magnetic tunnel junction at room temperature, which increased when cooled to low temperatures. Tunneling characteristics, such as the current-voltage behavior and temperature and bias dependence of the TMR, show the good quality of the organic tunnel barrier. Spin polarization (P) of the tunnel current through the Alq3 layer, directly measured using superconducting Al as the spin detector, shows that minimizing formation of an interfacial dipole layer between the metal electrode and organic barrier significantly improves spin transport. PMID:17358495

  2. The Interaction Between Shield, Ground and Tunnel Support in TBM Tunnelling Through Squeezing Ground

    Ramoni, M.; Anagnostou, G.

    2011-01-01

    When planning a TBM drive in squeezing ground, the tunnelling engineer faces a complex problem involving a number of conflicting factors. In this respect, numerical analyses represent a helpful decision aid as they provide a quantitative assessment of the effects of key parameters. The present paper investigates the interaction between the shield, ground and tunnel support by means of computational analysis. Emphasis is placed on the boundary condition, which is applied to model the interface between the ground and the shield or tunnel support. The paper also discusses two cases, which illustrate different methodical approaches applied to the assessment of a TBM drive in squeezing ground. The first case history—the Uluabat Tunnel (Turkey)—mainly involves the investigation of TBM design measures aimed at reducing the risk of shield jamming. The second case history—the Faido Section of the Gotthard Base Tunnel (Switzerland)—deals with different types of tunnel support installed behind a gripper TBM.

  3. Acute chylous peritonitis due to acute pancreatitis

    2012-01-01

    We report a case of acute chylous ascites formation presenting as peritonitis (acute chylous peritonitis) in a patient suffering from acute pancreatitis due to hypertriglyceridemia and alcohol abuse. The development of chylous ascites is usually a chronic process mostly involving malignancy, trauma or surgery, and symptoms arise as a result of progressive abdominal distention. However, when accumulation of “chyle” occurs rapidly, the patient may present with signs of peritonitis. Preoperative...

  4. Role of Inelastic Tunneling through the Barrier in Scanning Tunneling Microscope Experiments on Cuprates

    Pilgram, S.; T. M. Rice; Sigrist, M.

    2006-01-01

    The tunneling path between the CuO2-layers in cuprate superconductors and a scanning tunneling microscope tip passes through a barrier made from other oxide layers. This opens up the possibility that inelastic processes in the barrier contribute to the tunneling spectra. Such processes cause one or possibly more peaks in the second derivative current-voltage spectra displaced by phonon energies from the density of states singularity associated with superconductivity. Calculations of inelastic...

  5. Spin-polarized current and tunnel magnetoresistance in heterogeneous single-barrier magnetic tunnel junctions

    Petukhov, D. A.

    2016-06-01

    Current in heterogeneous tunnel junctions is studied in the framework of the parabolic conduction-band model. The developed model of the electron tunneling takes explicitly into account the difference of effective masses between ferromagnetic and insulating layers and between conduction subbands. Calculations for Fe/MgO/Fe-like structures have shown the essential impact of effective mass differences in regions (constituents) of the structure on the tunnel magnetoresistance of the junction.

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

    Li, H W; Kardynal, Beata; Ellis, D. J. P.; Shields, A.J.; Farrer, I.; Ritchie, D. A.

    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,...

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

    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.

  8. TBM tunnelling through unfavourable ground conditions : a case study, SSDS tunnel F, Hong Kong

    Lokusethu Hewage Don, Danuska Hasitha

    2013-01-01

    A study of the Strategic Sewage Disposal Scheme (SSDS) Stage 1 Tunnel F in Hong Kong was carried out as it is a great example of deep sub-sea hard rock TBM tunnelling through unfavourable, fault-affected ground conditions with heavy water inflows. The main objective of this study was to document events that took place during Tunnel F excavation and collate geological and geotechnical data related to the excavation, to aid future tunnel designers and contractors to assess the risk involved wit...

  9. Quantum size effects on spin-tunneling time in a magnetic resonant tunneling diode

    Saffarzadeh, Alireza; Daqiq, Reza

    2009-01-01

    We study theoretically the quantum size effects of a magnetic resonant tunneling diode (RTD) with a (Zn,Mn)Se dilute magnetic semiconductor layer on the spin-tunneling time and the spin polarization of the electrons. The results show that the spin-tunneling times may oscillate and a great difference between the tunneling time of the electrons with opposite spin directions can be obtained depending on the system parameters. We also study the effect of structural asymmetry which is related to t...

  10. Distribution of tunnelling times for quantum electron transport

    Rudge, Samuel; Kosov, Daniel

    2016-01-01

    In electron transport, the tunnelling time is the time taken for an electron to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for electron transport through a molecular junc...

  11. Quantum Tunnelling to the Origin and Evolution of Life

    Trixler, Frank

    2013-01-01

    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 ...

  12. Hi-tech Tunnel Sets World Record

    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.

  13. TBM tunneling on the Yucca Mountain Project

    The US Department of Energy's (DOE) Yucca Mountain Project (YMP) is a scientific endeavor to determine the suitability of Yucca Mountain for the first long-term, high-level nuclear waste repository in the United States. The current status of this long-term project from the construction perspective is described. A key element is construction of the Exploratory Studies Facility (ESF) Tunnel, which is being excavated with a 7.6 m (25 ft) diameter tunnel boring machine (TBM). Development of the ESF may include the excavation of over 15 km (9.3 mi) of tunnel varying in size from 3.0 to 7.6 m (10 to 25 ft). Prior to construction, extensive constructability reviews were an interactive part of the final design. The intent was to establish a constructable design that met the long-term stability requirements for radiological safety of a future repository, while maintaining flexibility for the scientific investigations and acceptable tunneling productivity

  14. Dynamical quenching of tunneling in molecular magnets

    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

  15. Program Analyzes Performance Of A Wind Tunnel

    Viterna, L. A.

    1994-01-01

    WT computer program developed to calculate rotor power required by, and output thrust produced by, fan in closed-loop wind tunnel. Uses blade-element theory to calculate aerodynamic forces along each blade of fan. Written in APL2.

  16. Some Connections between Quantum Tunneling and Inflation

    Norbury, J W

    1998-01-01

    The Wheeler-DeWitt equation in the minisuperspace approximation is studied in four different models. Under certain circumstances each model leads to a tunneling potential and under the same circumstances the classical version of each model leads to inflation.

  17. Many-electron tunneling in atoms

    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.

  18. Dynamical quenching of tunneling in molecular magnets

    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.

  19. LEP sees the end of the tunnel

    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.

  20. Unknotting tunnels in hyperbolic 3-manifolds

    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.

  1. Dielectric Sensors Based on Electromagnetic Energy Tunneling

    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.

  2. Tunneling rate in double quantum dots

    Filikhin, Igor; Matinyan, Sergei; Vlahovic, Branislav

    2014-03-01

    We study spectral properties of electron tunneling in double quantum dots (DQDs) (and double quantum wells (DQWs)) and their relation to the geometry. In particular we compare the tunneling in DQW with chaotic and regular geometry, taking into account recent evidence about regularization of the tunneling rate when the QW geometry is chaotic. Our calculations do not support this assumption. We confirm high influence of the QW geometry boundaries on the rate fluctuation along the spectrum. The factors of the effective mass anisotropy and violation of the symmetry of DQD and DQW are also considered. Generally, we found that the small violation of the symmetry drastically affects tunneling. This work is supported by the NSF (HRD-0833184) and NASA (NNX09AV07A).

  3. Electron tunneling across a tunable potential barrier

    We present an experiment where the elementary quantum electron tunneling process should be affected by an independent gate voltage parameter. We have realized nanotransistors where the source and drain electrodes are created by electromigration inducing a nanometer sized gap acting as a tunnel barrier. The barrier potential shape is in first approximation considered trapezoidal. The application of a voltage to the gate electrode close to the barrier region can in principle affect the barrier shape. Simulations of the source drain tunnel current as a function of the gate voltage predict modulations as large as one hundred percent. The difficulty of observing the predicted behaviour in our samples might be due to the peculiar geometry of the realized tunnel junction.

  4. Low Speed Wind Tunnel Facility (LSWTF)

    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...

  5. Teelt van vruchtgewassen in lage tunnels

    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

  6. Proton tunnelling in intermolecular hydrogen bonds

    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.

  7. 7 x 10 Foot Wind Tunnel

    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...

  8. Two-Dimensional Low-Turbulence Tunnel

    1938-01-01

    Manometer for the Two-Dimensional Low-Turbulence Tunnel. The Two-Dimensional Low-Turbulence Tunnel was originally called the Refrigeration or 'Ice' tunnel because it was intended to support research on aircraft icing. The tunnel was built of wood, lined with sheet steel, and heavily insulated on the outside. Refrigeration equipment was installed to generate icing conditions inside the test section. The NACA sent out a questionnaire to airline operators, asking them to detail the specific kinds of icing problems they encountered in flight. The replies became the basis for a comprehensive research program begun in 1938 when the tunnel commenced operation. Research quickly focused on the concept of using exhaust heat to prevent ice from forming on the wing's leading edge. This project was led by Lewis Rodert, who later would win the Collier Trophy for his work on deicing. By 1940, aircraft icing research had shifted to the new Ames Research Laboratory, and the Ice tunnel was refitted with screens and honeycomb. Researchers were trying to eliminate all turbulence in the test section. From TN 1283: 'The Langley two-dimensional low-turbulence pressure tunnel is a single-return closed-throat tunnel.... The tunnel is constructed of heavy steel plate so that the pressure of the air may be varied from approximately full vacuum to 10 atmospheres absolute, thereby giving a wide range of air densities. Reciprocating compressors with a capacity of 1200 cubic feet of free air per minute provide compressed air. Since the tunnel shell has a volume of about 83,000 cubic feet, a compression rate of approximately one atmosphere per hour is obtained. ... The test section is rectangular in shape, 3 feet wide, 7 1/2 feet high, and 7 1/2 feet long. ... The over-all size of the wind-tunnel shell is about 146 feet long and 58 feet wide with a maximum diameter of 26 feet. The test section and entrance and exit cones are surrounded by a 22-foot diameter section of the shell to provide a space

  9. Tunneling magnetoresistive heads for magnetic data storage.

    Mao, Sining

    2007-01-01

    Spintronics is emerging to be a new form of nanotechnologies, which utilizes not only the charge but also spin degree of freedom of electrons. Spin-dependent tunneling transport is one of the many kinds of physical phenomena involving spintronics, which has already found industrial applications. In this paper, we first provide a brief review on the basic physics and materials for magnetic tunnel junctions, followed more importantly by a detailed coverage on the application of magnetic tunneling devices in magnetic data storage. The use of tunneling magnetoresistive reading heads has helped to maintain a fast growth of areal density, which is one of the key advantages of hard disk drives as compared to solid-state memories. This review is focused on the first commercial tunneling magnetoresistive heads in the industry at an areal density of 80 approximately 100 Gbit/in2 for both laptop and desktop Seagate hard disk drive products using longitudinal media. The first generation tunneling magnetoresistive products utilized a bottom stack of tunnel junctions and an abutted hard bias design. The output signal amplitude of these heads was 3 times larger than that of comparable giant magnetoresistive devices, resulting in a 0.6 decade bit error rate gain over the latter. This has enabled high component and drive yields. Due to the improved thermal dissipation of vertical geometry, the tunneling magnetoresistive head runs cooler with a better lifetime performance, and has demonstrated similar electrical-static-discharge robustness as the giant magnetoresistive devices. It has also demonstrated equivalent or better process and wafer yields compared to the latter. The tunneling magnetoresistive heads are proven to be a mature and capable reader technology. Using the same head design in conjunction with perpendicular recording media, an areal density of 274 Gbit/in2 has been demonstrated, and advanced tunneling magnetoresistive heads can reach 311 Gbit/in2. Today, the

  10. Numerical simulation in tunneling - recent developments

    The paper presents recent findings of the Austrian joint research initiative 'Numerical Simulation in Tunneling'. The five year initiative, which was supported by the Austrian research fund, was started in 1997 with the main aim of developing and improving methods for the computer analysis of tunnels. The Problem areas that were looked at were: data acquisition and generation of input data, modeling strategies, visualization, material behavior and effects of water and air pressure. Only some topics are discussed here, others are presented in the mini-symposium Computational Methods in Tunneling. The topics that will be presented are: automatic acquisition of geological data (research performed at the institutes of rock mechanics and tunneling and the Institute for computer graphics and vision): a new system was developed that allows to create digital 3-D images of the tunnel face that can be interpreted by a geologist on a computer graphics work station. Some preliminary interpretation may be made by the software so that the work by the geologist is reduced. The interpreted data is used to generate the Input for numerical simulation models. Modeling strategies at the tunnel site (research performed at Institute of rock mechanics and tunneling): the feasibility of using three-dimensional modeling on site in order to interpret observation and measurements or to decide necessary support measures due to the occurrence of unforeseen geological features was investigated. The conclusion is, that if approached in an intelligent way three-dimensional modeling is feasible at the tunnel site and brings advantages. Visualization (research performed at the institute for structural analysis): numerical models of ten create a large amount of data, whose interpretation is difficult without advanced visualization techniques. The prototype of an advanced 3-D visualization system using virtual reality and a head-mounted display is presented. Refs. 2 (author)

  11. Quantization of Time in Dynamic Barrier Tunnelling

    Davison, Sydney G.; Davison, Timothy S.

    2016-01-01

    In the B\\"uttiker-Landauer perturbation approach to electron tunnelling, through a time-modulated rectilinear potential barrier, the Tien-Gordon identity was invoked, together with its infinite energy spectrum. Here, an exact treatment is presented which is based on the temporal wave-function matching procedure, that led to a finite energy spectrum. In seeking the condition governing the time evolution of the tunnelling process, the Euler formula provided the crucial ingredient for time quant...

  12. Andreev reflection and Klein tunneling in graphene

    Beenakker, C. W. J.

    2007-01-01

    This is a colloquium-style introduction to two electronic processes in a carbon monolayer (graphene), each having an analogue in relativistic quantum mechanics. Both processes couple electron-like and hole-like states, through the action of either a superconducting pair potential or an electrostatic potential. The first process, Andreev reflection, is the electron-to-hole conversion at the interface with a superconductor. The second process, Klein tunneling, is the tunneling through a p-n jun...

  13. Tribocorrosion challenges in tunnel boring machinery (TBM)

    Espallargas Alvarez, Nuria

    2015-01-01

    Tunnel Boring Machines (TBM) are used to bore tunnels, a specific area of interest for TBMs is their cutter heads, which is a massive steel structure with hardened steel disc cutters attached. The disc cutters can encounter all types of geology (i.e. from soft clays, slits, sands etc., to soft rock and extremely hard rock) and environments (i.e. dry, wet, seawater or chemical additives). These geologies and environments cause the disc cutters to be continuously exposed to degra...

  14. Geology of Pletovarje motorway tunnel (Slovenia

    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.

  15. Theoretical Analysis of Reinforcement Tunnel Lining Corrosion

    ZhiQiang Zhangand; Yousif A. Mansoor; Fan Hong Wei

    2013-01-01

    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 performan...

  16. Projection operator method for collective tunneling transitions

    Collective tunneling transitions take place in the case that a system has two nearly degenerate ground states with a slight energy splitting, which provides the time scale of the tunneling. The Liouville equation determines the evolution of the density matrix, while the Schroedinger equation determines that of a state. The Liouville equation seems to be more powerful for calculating accurately the energy splitting of two nearly degenerate eigenstates. However, no method to exactly solve the Liouville eigenvalue equation has been established. The usual projection operator method for the Liouville equation is not feasible. We analytically solve the Liouville evolution equation for nuclear collective tunneling from one Hartree minimum to another, proposing a simple and solvable model Hamiltonian for the transition. We derive an analytical expression for the splitting of energy eigenvalues from a spectral function of the Liouville evolution using a half-projected operator method. A full-order analytical expression for the energy splitting is obtained. We define the collective tunneling path of a microscopic Hamiltonian for collective tunneling, projecting the nuclear ground states onto n-particle n-hole state spaces. It is argued that the collective tunneling path sector of a microscopic Hamiltonian can be transformed into the present solvable model Hamiltonian. (author)

  17. Radio-frequency scanning tunnelling microscopy.

    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. PMID:17972882

  18. Theory of dissociative tunneling ionization

    Svensmark, Jens; Tolstikhin, Oleg I.; Madsen, Lars Bojer

    2016-05-01

    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 of 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 fields, where the BO approximation does not apply, the weak-field asymptotic theory describes the spectrum accurately.

  19. Some Caves in tunnels in Dinaric karst of Croatia

    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

  20. Acute arterial occlusion - kidney

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

  1. Acute Pancreatitis in Children

    ... a feeding tube or an IV to prevent malnutrition and improve healing. Does my child have to ... intestines. Can my child die from acute pancreatitis? Death from acute pancreatitis is quite rare in children– ...

  2. Diagnosing and Treating Acute Bronchitis

    ... Lung Disease Lookup > Acute Bronchitis Diagnosing and Treating Acute Bronchitis It is important to get your questions about ... Symptoms that last a few weeks How Is Acute Bronchitis Diagnosed? Healthcare providers diagnose acute bronchitis by asking ...

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

    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.

  4. Metformin induced acute pancreatitis

    Alsubaie, Sadeem; Almalki, Mussa H.

    2013-01-01

    Acute pancreatitis frequently presents with abdomen pain but may presents with various skin manifestations as rash and rarely, pancreatic panniculitis. Metformin, one of the most effective and valuable oral hypoglycemic agents in the biguanide class was linked to acute pancreatitis in few cases. Here, we report a case of metformin induce acute pancreatitis in young healthy man with normal renal function.

  5. Acute mastoiditis in children

    Anthonsen, Kristian; Høstmark, Karianne; Hansen, Søren;

    2013-01-01

    Conservative treatment of acute otitis media may lead to more complications. This study evaluates changes in incidence, the clinical and microbiological findings, the complications and the outcome of acute mastoiditis in children in a country employing conservative guidelines in treating acute ot...

  6. Recurrent acute renal failure

    Satish, S.; Rajesh, R.; Kurian, G.; Seethalekshmi, N. V.; Unni, M.; Unni, V. N.

    2010-01-01

    While acute renal failure secondary to intravascular hemolysis is well described in hemolytic anemias, recurrent acute renal failure as the presenting manifestation of a hemolytic anemia is rare. We report a patient with recurrent acute renal failure who was found to have paroxysmal nocturnal hemoglobinuria (PNH), on evaluation.

  7. A Tunnel Compress Scheme for Multi-Tunneling in PMIPv6-based Nested NEMO

    Youn-Hee Han

    2010-11-01

    Full Text Available In nested NEMO, a multi-tunneling causes a pinball routing problem. Several solutions proposed tosolve the pinball routing problem in NEMO BSP cannot be used at PMIPv6-based NEMO due todifferent environment such as no route optimization with CN. We propose a tunnel compress scheme formulti-tunneling in PMIPv6-based NEMO. The scheme consists of two parts: the first part is an interdomainor wired Internet part. The other is an intra part of nested mobile networks. In the inter-domainpart, single IP-in-IP tunnel is created by connecting an innermost entry point with an outermost exitpoint in original multi-tunnels. As the same way used in the inter-domain part, single IP-in-IP tunnel iscreated from the outermost exit point and an innermost exit point in original multi-tunnels. In theproposed scheme, IP-in-IP encapsulated packets are forwarded using host-based routing withoutmodifying the outer header. The information to compress multi-tunnels is piggybacked at the PMIPv6signaling.

  8. Static and dynamic aspects of spin tunnelling in crystalline magnetic tunnel junctions

    Single-crystal magnetic tunnel junctions employing bcc (100) Fe electrodes and MgO(100) insulating barrier are elaborated by molecular beam epitaxy. The magneto-transport properties are investigated in two extreme regimes. First, for extremely small MgO thickness, we show that the equilibrium tunnel transport in Fe/MgO/Fe systems leads to antiferromagnetic interactions, mediated by the tunnelling of the minority spin interfacial resonance state. Second, for large MgO barrier thickness, the tunnel transport validates specific spin filtering effects in terms of symmetry of the electronic Bloch function and symmetry-dependent wavefunction attenuation in the single-crystal barrier. Within this framework, we present giant tunnel magnetoresistive effects at room temperature (125-160%). Moreover, we illustrate that the interfacial chemical and electronic structure plays a crucial role in the spin filtering. We point out imperfect filtering effects and a strong implication of the minority surface state of Fe on the low voltage variation of tunnel magnetoresistance. The insertion of carbon impurities at the Fe/MgO interface changes radically the voltage response of the tunnel magnetoresistance and activates a resonant tunnelling mechanism via the interfacial resonance state

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

    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 res...

  10. Tunnelling in Soft Soil: Tunnel Boring Machine Operation and Soil Response

    Festa, D.; Broere, W.; Bosch, J.W.

    2013-01-01

    Constructing tunnels in soft soil with the use of Tunnel Boring Machines may induce settlements including soil movements ahead of the face, soil relaxation into the tail void, possible heave due to grouting, long lasting consolidation processes, and potentially several other mechanisms. A considerab

  11. European Tunnelling Review Quality, Environment and Safety Focus

    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. The Cause of Shallow Tunnel Collapse and Simulation Analysis of Consolidation for a Collapsed Tunnel

    Shucai Li

    2013-03-01

    Full Text Available In order to ensure the safety of the shallow tunnels construction, it is very important to find the reasons of the collapse. During Fujiachong tunnel construction, collapse of the section Yk25 + 547~Yk25 + 552. Distributions of cracked surrounding rock, rainfall, geological forecast were discussed for reason of tunnel collapse. According to in-situ construction condition, reinforced support program was applied to the surrounding rock consolidation of the tunnel. In order to assess consolidation effect, a cross-sections of collapse zone measurement was increased and simulation analysis was applied to the section. The results of in-situ measurement and simulation results show that tunneling collapse zone was consolidated by reinforced support program successfully.

  13. Management Of Acute Migraine

    Mehndiratta M

    2002-01-01

    Full Text Available Pharmacotherapy for migraine involves treatment for the acute attack as well as using long-term prophylaxis in order to reduce the frequency and severity of the attacks. Based on severity, there are a number of drugs available to treat the acute attacks. For mild to moderate attacks, analgesics, NSAIDs and Ergotamine are effective but severe attacks may need Dihydroergotamine (DHE or a triptan. Sumatriptan and the second generation triptans have revolutionized the acute treatment of migraine. Early and appropriate treatment holds the key to successful therapy of the acute attack. This article discusses the various acute treatment options available.

  14. Computational Simulation of Semispan Wings in Wind Tunnels

    Olsen, Mike; Rizk, Yehia

    1998-01-01

    The computational modelling of experiments, with the end aim of providing sufficiently accurate simulations to assess and improve turbulence models is described. Solid wall tunnels are the only tunnels in which the boundary conditions can, in principle, be known exactly. The modelling of the tunnel walls for transonic flows requires the accurate modelling of the viscous displacement effects on the tunnel walls. This paper describes the modelling of semispan wing experiments in solid wall tunnels, with the tunnel walls modelled as inviscid walls, and with all 4 walls modelled viscously. The effect of the viscous effects is discussed, as well as the feasibility of modelling these effects in an inviscid, apriori manner.

  15. Modelling of interband transitions in GaAs tunnel diode

    Louarn, K.; Fontaine, C.; Arnoult, A.; Olivié, F.; Lacoste, G.; Piquemal, F.; Bounouh, A.; Almuneau, G.

    2016-06-01

    In this paper, an improved model for non-local band-to-band tunneling carrier transport is presented and compared to experimental measurement from GaAs tunnel junctions devices. By carefully taking into account the coupling between the conduction band and the light holes valence band, the model is able to predict, with realistic material parameters, the amplitude of the current density throughout the whole tunneling regime. The model suggests that elastic band-to-band tunneling instead of trap-assisted-tunneling is the predominant mechanism in GaAs tunnel junctions, which is of great interest for better understanding and improving III–V multi-junction solar cells.

  16. Acute loss of consciousness.

    Tristán, Bekinschtein; Gleichgerrcht, Ezequiel; Manes, Facundo

    2015-01-01

    Acute loss of consciousness poses a fascinating scenario for theoretical and clinical research. This chapter introduces a simple yet powerful framework to investigate altered states of consciousness. We then explore the different disorders of consciousness that result from acute brain injury, and techniques used in the acute phase to predict clinical outcome in different patient populations in light of models of acute loss of consciousness. We further delve into post-traumatic amnesia as a model for predicting cognitive sequels following acute loss of consciousness. We approach the study of acute loss of consciousness from a theoretical and clinical perspective to conclude that clinicians in acute care centers must incorporate new measurements and techniques besides the classic coma scales in order to assess their patients with loss of consciousness. PMID:25702218

  17. Channel selective tunnelling through a nanographene assembly.

    Wong, H S; Feng, X; Müllen, K; Chandrasekhar, N; Durkan, C

    2012-03-01

    We report selective tunnelling through a nanographene intermolecular tunnel junction achieved via scanning tunnelling microscope tip functionalization with hexa-peri-hexabenzocoronene (HBC) molecules. This leads to an offset in the alignment between the energy levels of the tip and the molecular assembly, resulting in the imaging of a variety of distinct charge density patterns in the HBC assembly, not attainable using a bare metallic tip. Different tunnelling channels can be selected by the application of an electric field in the tunnelling junction, which changes the condition of the HBC on the tip. Density functional theory-based calculations relate the imaged HBC patterns to the calculated molecular orbitals at certain energy levels. These patterns bear a close resemblance to the π-orbital states of the HBC molecule calculated at the relevant energy levels, mainly below the Fermi energy of HBC. This correlation demonstrates the ability of an HBC functionalized tip as regards accessing an energy range that is restricted to the usual operating bias range around the Fermi energy with a normal metallic tip at room temperature. Apart from relating to molecular orbitals, some patterns could also be described in association with the Clar aromatic sextet formula. Our observations may help pave the way towards the possibility of controlling charge transport between organic interfaces. PMID:22322294

  18. Tunnel Ventilation Control Using Reinforcement Learning Methodology

    Chu, Baeksuk; Kim, Dongnam; Hong, Daehie; Park, Jooyoung; Chung, Jin Taek; Kim, Tae-Hyung

    The main purpose of tunnel ventilation system is to maintain CO pollutant concentration and VI (visibility index) under an adequate level to provide drivers with comfortable and safe driving environment. Moreover, it is necessary to minimize power consumption used to operate ventilation system. To achieve the objectives, the control algorithm used in this research is reinforcement learning (RL) method. RL is a goal-directed learning of a mapping from situations to actions without relying on exemplary supervision or complete models of the environment. The goal of RL is to maximize a reward which is an evaluative feedback from the environment. In the process of constructing the reward of the tunnel ventilation system, two objectives listed above are included, that is, maintaining an adequate level of pollutants and minimizing power consumption. RL algorithm based on actor-critic architecture and gradient-following algorithm is adopted to the tunnel ventilation system. The simulations results performed with real data collected from existing tunnel ventilation system and real experimental verification are provided in this paper. It is confirmed that with the suggested controller, the pollutant level inside the tunnel was well maintained under allowable limit and the performance of energy consumption was improved compared to conventional control scheme.

  19. Graphene-based magnetic tunnel junctions

    Cobas, Enrique

    2013-03-01

    Graphene's in-plane transport has been widely researched and has yielded extraordinary carrier mobilities of 105 cm2/Vs and spin diffusion lengths of exceeding 100 μm. These properties bode well for graphene in future electronics and spintronics technologies. Its out-of-plane transport has been far less studied, although its parent material, graphite, shows a large conductance anisotropy. Recent calculations show graphene's interaction with close-packed ferromagnetic metal surfaces should produce highly spin-polarized transport out-of-plane, an enabling breakthrough for spintronics technology. In this work, we fabricate and measure FM/graphene/FM magnetic tunnel junctions using CVD-grown single-layer graphene. The resulting juctions show non-linear current-voltage characteristics and a very weak temperature dependence consistent with charge tunneling transport. Furthermore, we study spin transport across the junction as a function of bias voltage and temperature. The tunneling magnetoresistance (TMR) peaks at two percent for single-layer graphene junctions and exhibits the expected bias asymmetry and a temperature dependence that fits well with established spin-polarized tunneling models. Results of mutli-layer graphene tunnel junctions will also be discussed.

  20. Particle detection with superconducting tunnel junctions

    At the Institute of Experimental Nuclear Physics of the University of Karlsruhe (TH) and at the Institute for Nuclear Physics of the Kernforschungszentrum Karlsruhe we started to produce superconducting tunnel junctions and to investigate them for their suitability as particle detectors. The required facilities for the production of tunnel junctions and the experimental equipments to carry out experiments with them were erected. Experiments are presented in which radiations of different kinds of particles could successfully be measured with the tunnel junctions produced. At first we succeeded in detectioning light pulses of a laser. In experiments with alpha-particles of an energy of 4,6 MeV the alpha-particles were detected with an energy resolution of 1,1%, and it was shown in specific experiments that the phonons originating from the deposition of energy by an alpha-particle in the substrate can be detected with superconducting tunnel junctions at the surface. On that occasion it turned out that the signals could be separated with respect to their point of origin (tunnel junction, contact leads, substrate). Finally X-rays with an energy of 6 keV were detected with an energy resolution of 8% in a test arrangement that makes use of the so-called trapping effect to read out a larger absorber volume. (orig.)

  1. Fire safety assessment of tunnel structures

    Gkoumas, Konstantinos; Giuliani, Luisa; Petrini, Francesco;

    2011-01-01

    Tunnels and underground structures are becoming more and more essential these days, when installing new transportation infrastructures in congested areas as well as when raising the qualities within the existing urbanizations. The realization of such structures calls for specific measures regarding...... 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.......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...

  2. Electronic thermometry in tunable tunnel junction

    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. Measuring quantum systems with tunnel junctions

    Full text: We present a formalism that allows to describe a quantum system modulating the transmission of a tunnel junction. The tunnel junction acts as an environment for the quantum system. Contrary to the conventional approach to open quantum systems we retain a degree of freedom of the environment, the charge passed through the junction, after averaging over the bath degrees of freedom, employing a projection operator technique. The resulting object characterizing the joint dynamics of the system and the charge is the charge specific density matrix. We derive a master equation describing the time evolution of the charge specific density matrix. We consider two examples of quantum systems coupled to the junction: a spin and a harmonic oscillator. In the spin case we are able to analyze a quantum measurement process in detail. For the oscillator we investigate the noise in the tunnel junction induced by the coupling. (author)

  4. Phonon tunneling through a double barrier system

    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.

  5. Positioning systems for underground tunnel environments

    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...

  6. Thermal stratified wind tunnel in IHI

    The stability of the atmospheric boundary layer is based on the Richardson number. A large temperature gradient or a very low wind speed is required to achieve strong stability in a wind tunnel. A thermal stratified boundary layer wind tunnel has been developed. This wind tunnel is designed to achieve a large temperature gradient by cooling the floor of the test section with liquid nitrogen. The floor temperature ranges from - 185degC to room temperature. The space heating unit has 10 horizontal stories. Each of them is controlled independently. The test section gets the temperature of 70degC at 2 m/s wind speed. Three kinds of stable conditions and a neutral condition are provided for concentration measurement. In the stable condition, both lateral and vertical plume widths are narrower than under neutral condition. (author)

  7. Multidimensional Quantum Tunneling in the Schwinger Effect

    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...

  8. Spin-polarized scanning tunnelling microscopy

    The recent experimental progress in spin-polarized scanning tunnelling microscopy (SP-STM) - a magnetically sensitive imaging technique with ultra-high resolution - is reviewed. The basics of spin-polarized electron tunnelling are introduced as they have been investigated in planar tunnel junctions for different electrode materials, i.e. superconductors, optically excited GaAs, and ferromagnets. It is shown that ferromagnets and antiferromagnets are suitable tip materials for the realization of SP-STM. Possible tip designs and modes of operations are discussed for both classes of materials. The results of recent spatially resolved measurements as performed with different magnetic probe tips and using different modes of operation are reviewed and discussed in terms of applicability to surfaces, thin films, and nanoparticles. The limits of spatial resolution, and the impact of an external magnetic field on the imaging process

  9. Scanning Tunneling Spectroscope Use in Electrocatalysis Testing

    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.

  10. Silicon spintronics with ferromagnetic tunnel devices

    In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

  11. Numerical studies of electron tunnelling in liquids

    The diffusion equation, derived from Fick's second law, with an added exponential sink term to simulate electron tunnelling, is integrated numerically to determine the rate of electron decay at times greater than 1 ps. The effect of a Coulomb interaction with a charged scavenger is examined and the steady-state rate constant shown to approximate closely to that obtained by combining the separate effects of tunnelling and charge-affected diffusion, which can be expressed analytically. Diffusion in the presence of a charge-induced dipole interaction is investigated for the case of scavenging of localised electrons in alkanes. The rate constant is shown to be dominated by random diffusion and tunnelling and the bias induced by the interaction is of little consequence. The sensitivity of the rate constant to changes in the pre-exponential factor in the sink term is shown to be most favourable at short times. (author)

  12. Vibration Compensation for Scanning Tunneling Microscope

    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.

  13. Quantum tunneling from paths in complex time

    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.

  14. SKB - PNC. Development of tunnel radar antennas

    Tunnel antennas for the RAMAC borehole radar system have been developed and tested in the field. The antennas are of the loaded dipole type and the receiver and transmitter electronics have been rebuilt to screen them from the antennas. A series of measurements has demonstrated that the radar pulse is short and well shaped and relatively free from ringing, even compared with the existing borehole antennas. Two antenna sets were tested: one centered at 60 MHz and another above 100 MHz. Both produced excellent radar pictures when tested in tunnels in Stripa mine. The antennas have been designed to be easy to carry, since the signal quality often depends on the way the antenna is held relative to electric conductors in the tunnels. (au) (46 figs., 57 refs.)

  15. Vibration analysis of wind tunnel support

    张旭; 张家泰; 董国庆; 张国友; 刘德富

    2004-01-01

    In order to enable a wind tunnel support to have a high enough natural frequency to prevent experiencing mechanical resonance and excessive vibration displacement, five kinds of wind tunnel support structures have been simulated and analyzed individually under five different load conditions by means of a nonlinear finite element numerical method. With natural frequency and three directions vibration displacement given, simulation and analyses indicated that additional supports is more beneficial than heightening the rigidity of steel reinforced concrete in support pillars and adopting steel wrappers on the pillars to increase natural frequency of support structure. Increasing the rigidity of steel reinforced concrete, adopting steel wrappers and providing additional supports are all helpful in reducing three directions vibration Max displacement. and additional supports are comparatively more effective. Therefore, a structure scheme with steel reinforced concrete support pillars,steel wrappers and additional supports should be adopted in practical wind tunnel support construction.

  16. Coupling quantum tunneling with cavity photons.

    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. PMID:22491095

  17. The Tunnel Boring Machine Advancements in Horizontal and Up-Hill Tunnels

    Stefano Fuoco

    2009-01-01

    Full Text Available Problem statement: Nowadays high levels of experience have been acquired in the excavation of horizontal tunnels using TBM, especially as far as tunnels with small diameters (about 4 m wide are concerned. Less experience has been acquired in the excavation of tunnels under difficult alignment conditions, as in the case of steeply inclined excavations (up-hill tunnels. Approach: This study presented the results of studies which compare the production data collected for tunnels excavated with TBM in "normal" conditions (horizontal tunnel, with those derived from steeply inclined excavations (up-hill tunnels. Results: From an examination of the results obtained in the studied cases a net difference appears evident in terms of productivity between horizontal and up-hill excavations. Conclusion: Such net difference between horizontal and up-hill excavation productions can be attributed to the greater burdens of times necessary for the supply of materials and personnel, the regripping operations with fall preventer systems and, in general, the greater difficulties of carrying out ordinary and extraordinary maintenance of the machines in particularly difficult altrimetric conditions.

  18. Carbonaceous aerosols in an urban tunnel

    Ancelet, Travis; Davy, Perry K.; Trompetter, William J.; Markwitz, Andreas; Weatherburn, David C.

    2011-08-01

    Particulate matter in the Mount Victoria Tunnel, an urban road tunnel 623 m in length with an average traffic volume of 2070-2300 vehicles per hour located in Wellington, New Zealand, was studied to gain an understanding of carbonaceous species emitted from motor vehicles. The average PM 2.5 concentration during peak hours in the tunnel was found to be 67.6 ± 19.4 μg m -3. Analysis of carbonaceous species present (OC, EC, TC) was performed by both the NIOSH and IMPROVE thermal/optical protocols and carbonaceous species were found to make up 63-73% of the total PM in the tunnel. Comparison of TC concentrations obtained from each protocol revealed that no significant difference was present between the two protocols. Black carbon (BC), also used as a measure of EC, was determined using light reflection and BC values did not differ significantly from EC concentrations determined using the NIOSH and IMPROVE protocols. TC was also determined using EA/IRMS and it was found that TC concentrations from EA/IRMS directly correlated with TC results obtained using the NIOSH protocol. Stable isotope analysis of the PM 2.5 yielded δ 13C values from -24.7 to -28.3‰, typical of motor vehicles. Analysis of particle-phase PAHs by thermal desorption GC/MS revealed an average total PAH concentration of 70.0 ± 4.1 ng m -3 and PAHs were found to contribute 0.10% of total PM 2.5 in the tunnel. PAH emissions in the tunnel were found to be enriched in low molecular weight PAHs, indicative of emissions from diesel-fueled vehicles. Analysis of individual particle composition and morphology revealed that most particles were carbonaceous species that formed large, amorphous agglomerates made up of smaller spherules.

  19. Acute pancreatitis in acute viral hepatitis

    2007-01-01

    AIM: To elucidate the frequency and characteristics of pancreatic involvement in the course of acute (nonfulminant) viral hepatitis.METHODS: We prospectively assessed the pancreatic involvement in patients with acute viral hepatitis who presented with severe abdomimanl pain.RESULTS: We studied 124 patients with acute viral hepatitis, of whom 24 presented with severe abdominal pain. Seven patients (5.65%) were diagnosed to have acute pancreatitis. All were young males. Five patients had pancreatitis in the first week and two in the fourth week after the onset of jaundice. The pancreatitis was mild and all had uneventful recovery from both pancreatitis and hepatitis on conservative treatment.The etiology of pancreatitis was hepatitis E virus in 4,hepatitis A virus in 2, and hepatitis B virus in 1 patient.One patient had biliary sludge along with HEV infection.The abdominal pain of remaining seventeen patients was attributed to stretching of Glisson's capsule.CONCLUSION: Acute pancreatitis occurs in 5.65% of patients with acute viral hepatitis, it is mild and recovers with conservative management.

  20. Acute chylous peritonitis due to acute pancreatitis.

    Georgiou, Georgios K; Harissis, Haralampos; Mitsis, Michalis; Batsis, Haralampos; Fatouros, Michalis

    2012-04-28

    We report a case of acute chylous ascites formation presenting as peritonitis (acute chylous peritonitis) in a patient suffering from acute pancreatitis due to hypertriglyceridemia and alcohol abuse. The development of chylous ascites is usually a chronic process mostly involving malignancy, trauma or surgery, and symptoms arise as a result of progressive abdominal distention. However, when accumulation of "chyle" occurs rapidly, the patient may present with signs of peritonitis. Preoperative diagnosis is difficult since the clinical picture usually suggests hollow organ perforation, appendicitis or visceral ischemia. Less than 100 cases of acute chylous peritonitis have been reported. Pancreatitis is a rare cause of chyloperitoneum and in almost all of the cases chylous ascites is discovered some days (or even weeks) after the onset of symptoms of pancreatitis. This is the second case in the literature where the patient presented with acute chylous peritonitis due to acute pancreatitis, and the presence of chyle within the abdominal cavity was discovered simultaneously with the establishment of the diagnosis of pancreatitis. The patient underwent an exploratory laparotomy for suspected perforated duodenal ulcer, since, due to hypertriglyceridemia, serum amylase values appeared within the normal range. Moreover, abdominal computed tomography imaging was not diagnostic for pancreatitis. Following abdominal lavage and drainage, the patient was successfully treated with total parenteral nutrition and octreotide. PMID:22563182

  1. Acute chylous peritonitis due to acute pancreatitis

    Georgios K Georgiou; Haralampos Harissis; Michalis Mitsis; Haralampos Batsis; Michalis Fatouros

    2012-01-01

    We report a case of acute chylous ascites formation presenting as peritonitis (acute chylous peritonitis) in a patient suffering from acute pancreatitis due to hypertriglyceridemia and alcohol abuse.The development of chylous ascites is usually a chronic process mostly involving malignancy,trauma or surgery,and symptoms arise as a result of progressive abdominal distention.However,when accumulation of "chyle" occurs rapidly,the patient may present with signs of peritonitis.Preoperative diagnosis is difficult since the clinical picture usually suggests hollow organ perforation,appendicitis or visceral ischemia.Less than 100 cases of acute chylous peritonitis have been reported.Pancreatitis is a rare cause of chyloperitoneum and in almost all of the cases chylous ascites is discovered some days (or even weeks) after the onset of symptoms of pancreatitis.This is the second case in the literature where the patient presented with acute chylous peritonitis due to acute pancreatitis,and the presence of chyle within the abdominal cavity was discovered simultaneously with the establishment of the diagnosis of pancreatitis.The patient underwent an exploratory laparotomy for suspected perforated duodenal ulcer,since,due to hypertriglyceridemia,serum amylase values appeared within the normal range.Moreover,abdominal computed tomography imaging was not diagnostic for pancreatitis.Following abdominal lavage and drainage,the patient was successfully treated with total parenteral nutrition and octreotide.

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

    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.

  3. Application Of Artificial Intelligence To Wind Tunnels

    Lo, Ching F.; Steinle, Frank W., Jr.

    1989-01-01

    Report discusses potential use of artificial-intelligence systems to manage wind-tunnel test facilities at Ames Research Center. One of goals of program to obtain experimental data of better quality and otherwise generally increase productivity of facilities. Another goal to increase efficiency and expertise of current personnel and to retain expertise of former personnel. Third goal to increase effectiveness of management through more efficient use of accumulated data. System used to improve schedules of operation and maintenance of tunnels and other equipment, assignment of personnel, distribution of electrical power, and analysis of costs and productivity. Several commercial artificial-intelligence computer programs discussed as possible candidates for use.

  4. Dihydroazulene photoswitch operating in sequential tunneling regime

    Broman, Søren Lindbæk; Lara-Avila, Samuel; Thisted, Christine Lindbjerg;

    2012-01-01

    to electrodes so that the electron transport goes by sequential tunneling. To assure weak coupling, the DHA switching kernel is modified by incorporating p-MeSC6H4 end-groups. Molecules are prepared by Suzuki cross-couplings on suitable halogenated derivatives of DHA. The synthesis presents an...... VHF. One derivative, incorporating a p-MeSC6H4 anchoring group in one end, has been placed in a silver nanogap. Conductance measurements justify that transport through both DHA (high resistivity) and VHF (low resistivity) forms goes by sequential tunneling. The switching is fairly reversible and...

  5. Fire Resistant Panels for the Tunnel Linings

    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.

  6. Wind Tunnel Measurements at LM Wind Power

    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...

  7. Phonoemissive Spin Tunneling in Molecular Nanomagnets

    Garg, Anupam

    2011-01-01

    A new mechanism is proposed for the magnetization reversal of molecular nanomagnets such as \\Fe8. In this process the spin tunnels from the lowest state near one easy direction to the first excited state near the opposite easy direction, and subsequently decays to the second easy direction with the emission of a phonon, or it first emits a phonon and then tunnels to the final state. This mechanism is the simplest imaginable one that allows magnetization relaxation in the presence of a longitu...

  8. Quantum time scales in alpha tunneling

    Kelkar, N G; Nowakowski, M

    2008-01-01

    The theoretical treatment of alpha decay by Gamow is revisited by investigating the quantum time scales in tunneling. The time spent by an alpha particle in front of the barrier and traversing it before escape is evaluated using microscopic alpha nucleus potentials. The half-life of a nucleus is shown to correspond to the time spent by the alpha knocking in front of the barrier. Calculations for medium and super heavy nuclei show that from a multitude of available tunneling time definitions, the transmission dwell time gives the bulk of the lifetime of the decaying state, in most cases.

  9. Traceable long range scanning tunneling microscopy

    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.

  10. A study for the KAERI research tunnel

    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

  11. Generalized Bessel functions in tunnelling ionization

    Reiss, H R

    2003-01-01

    We develop two new approximations for the generalized Bessel function that frequently arises in the analytical treatment of strong-field processes, especially in non-perturbative multiphoton ionization theories. Both these new forms are applicable to the tunnelling environment in atomic ionization, and are analytically much simpler than the currently used low-frequency asymptotic approximation for the generalized Bessel function. The second of the new forms is an approximation to the first, and it is the second new form that exhibits the well-known tunnelling exponential.

  12. Spintronics: manganite-based magnetic tunnel structures

    A topical and highly promising aspect of the field of spintronics is the physics involved in the flow of a spin-polarized current through magnetic tunnel structures. This review focuses on manganite-based structures, which are appealing for their high Curie temperature, highly spin-polarized conduction electrons, high chemical stability, and well-developed fabrication technology. Particular emphasis is placed on some novel approaches to studying the tunnel structures, including the use of planar geometry and the application of combined external factors (microwave and optical radiation) to investigate spin-polarized transport. (reviews of topical problems)

  13. Dielectric Engineered Tunnel Field-Effect Transistor

    Ilatikhameneh, Hesameddin; Tarek A. Ameen; Klimeck, Gerhard; Appenzeller, Joerg; Rahman, Rajib

    2015-01-01

    The dielectric engineered tunnel field-effect transistor (DE-TFET) as a high performance steep transistor is proposed. In this device, a combination of high-k and low-k dielectrics results in a high electric field at the tunnel junction. As a result a record ON-current of about 1000 uA/um and a subthreshold swing (SS) below 20mV/dec are predicted for WTe2 DE-TFET. The proposed TFET works based on a homojunction channel and electrically doped contacts both of which are immune to interface stat...

  14. Reliability assessment of tunneling flow charts

    When driving horizontal workings of different kinds it is typical to reserve excessive redundant equipment. However, the lack of resources (facilities, people) and poor management don't ensure goal achievement [3]. The paper presents reliability assessment method of tunneling with the help of mathematical modeling. The mathematical model is developed on the basis of factual data of tunneling conditions and no-failure operation probabilities of the flow chart elements are estimated. The method of reliability assessment allows identifying organizational, technological and technical elements of the reserves to increases drive efficiency and improve feasibility characteristics

  15. Vibration measurement and modal analysis for tunneller

    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. Reliability assessment of tunneling flow charts

    Antropova, N. A.; Krets, V. G.; Luk'yanov, V. G.; Baranova, A. V.

    2015-02-01

    When driving horizontal workings of different kinds it is typical to reserve excessive redundant equipment. However, the lack of resources (facilities, people) and poor management don't ensure goal achievement [3]. The paper presents reliability assessment method of tunneling with the help of mathematical modeling. The mathematical model is developed on the basis of factual data of tunneling conditions and no-failure operation probabilities of the flow chart elements are estimated. The method of reliability assessment allows identifying organizational, technological and technical elements of the reserves to increases drive efficiency and improve feasibility characteristics.

  17. Probing Klein tunnelling through quantum quenches

    We study the interplay between an inhomogeneous quantum quench of the external potential in a system of relativistic fermions in one-dimension and the well-known Klein tunneling. We find that the large time evolution is characterized by particle production at a constant rate which we derive analytically. The produced particles can be physically interpreted according to a semiclassical picture and the state reached in the long time limit can be classified as a non-equilibrium-steady-state. Such a quantum quench can be used in order to observe macroscopic effects of Klein tunneling in transport, with potential implementations with current experimental setups. (paper)

  18. A Tunnel Compress Scheme for Multi-Tunneling in PMIPv6-based Nested NEMO

    Youn-Hee Han; Hyo-Beom Lee; Min-Soo Woo; Sung-Gi Min

    2010-01-01

    In nested NEMO, a multi-tunneling causes a pinball routing problem. Several solutions proposed tosolve the pinball routing problem in NEMO BSP cannot be used at PMIPv6-based NEMO due todifferent environment such as no route optimization with CN. We propose a tunnel compress scheme formulti-tunneling in PMIPv6-based NEMO. The scheme consists of two parts: the first part is an interdomainor wired Internet part. The other is an intra part of nested mobile networks. In the inter-domainpart, singl...

  19. Spin-polarized tunneling in MgO-based tunnel junctions with superconducting electrodes

    Schebaum, Oliver; Fabretti, Savio; Moodera, Jagadeesh S.; Thomas, Andy

    2012-03-01

    We prepared magnetic tunnel junctions with one ferromagnetic and one superconducting Al-Si electrode. Pure cobalt electrodes were compared with a Co-Fe-B alloy and the Heusler compound Co2FeAl. The polarization of the tunneling electrons was determined using the Maki-Fulde model and is discussed along with the spin-orbit scattering and the total pair-breaking parameters. The junctions were post-annealed at different temperatures to investigate the symmetry filtering mechanism responsible for the giant tunneling magnetoresistance ratios in Co-Fe-B/MgO/Co-Fe-B junctions.

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

    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...

  1. Acute renal failure associated with nonfulminant acute viral hepatitis A

    Sarawgi, S.; Gupta, A. K.; Arora, D S; Jasuja, S.

    2008-01-01

    Hepatitis A runs a benign course in children, but may have atypical presentations in adults. Very rarely acute renal failure complicates nonfulminant hepatitis A. We report a patient with nonfulminant acute viral hepatitis A with multiorgan involvement. Patient had biopsy proven acute interstitial nephritis, acute pancreatitis, acute myocarditis and required hemodialysis for 6 weeks.

  2. The effect of the tortoise coordinates on the tunnel effect

    Gui-hua, T; Wang, S; Gui-hua, Tian; Zheng, Zhao; Wang, Shi-kun

    2006-01-01

    The tunnel process of the quantum wave from the light cone is carefully discussed. They are applied in the massive quantum particles from the Schwarzschild black hole in the Kruskal metric. The tortoise coordinates prevent one from understanding the tunnel process, and are investigated with care. Furthermore, the massive particles could come out of the black hole either by the Hawking radiation or by the tunnel effect; the tunnel effect might give more information about the black hole.

  3. Diagnosis of carpal tunnel syndrome. Ultrasound versus electromyography.

    Lee, D; van Holsbeeck, M T; Janevski, P K; Ganos, D L; Ditmars, D M; Darian, V B

    1999-07-01

    This article presents a new technique for diagnosing carpal tunnel syndrome using ultrasound. The ultrasound characteristics of the normal and abnormal median nerve are discussed in relation to carpal tunnel syndrome. The development of ultrasound as a new diagnostic modality for carpal tunnel syndrome is presented in a three-part study correlating the ultrasound measurements of the median nerve and electromyogram of the median nerve. A new algorithm for evaluating patients with carpal tunnel syndrome is presented. PMID:10442084

  4. Analysis of Ground Deformations Induced by Tunnel Excavation

    Mingli Huang

    2012-08-01

    Full Text Available In this study, we analyzing the ground deformation response in water-bearing sandstone ground caused by tunnel excavation. Moreover, based on the field monitoring data of Xiang-an subaqueous tunnel in Xiamen, taking a deep research on ground deformations caused by large cross section tunnel excavation. From our research results, during tunnel excavation surface settlement and extensometer settlement may be divided into four stages: slight deformation stage, rapid deformation stage, stable stage and slow deformation stage.

  5. Analysis of Ground Deformations Induced by Tunnel Excavation

    Mingli Huang; Jia Guo; Zhongsheng Tan

    2012-01-01

    In this study, we analyzing the ground deformation response in water-bearing sandstone ground caused by tunnel excavation. Moreover, based on the field monitoring data of Xiang-an subaqueous tunnel in Xiamen, taking a deep research on ground deformations caused by large cross section tunnel excavation. From our research results, during tunnel excavation surface settlement and extensometer settlement may be divided into four stages: slight deformation stage, rapid deformation stage, stable sta...

  6. Energetically constrained co-tunneling of cold atoms

    Kolovsky, Andrey R.; Link, Julia; Wimberger, Sandro

    2011-01-01

    We study under-barrier tunneling for a pair of energetically bound bosonic atoms in an optical lattice with a barrier. We identify conditions under which this exotic molecule tunnels as a point particle with the coordinate given by the bound pair center of mass and discuss the atomic co-tunneling beyond this regime. In particular, we quantitatively analyze resonantly enhanced co-tunneling, where two interacting atoms penetrate the barrier with higher probability than a single atom.

  7. Plasmon-induced tunneling currents : the influence of tip modes

    Baur, Christof; Rettenberger, Armin; Dransfeld, Klaus; Leiderer, Paul; Koslowski, Berndt; Möller, Rolf; P. Johansson

    1995-01-01

    The interaction of propagating surface plasmons (PSP) excited in a silver film with the tunneling junction of a scanning tunneling microscope has been investigated. Under particular conditions we find strong plasmon-induced current (PIC) superimposed on the tunneling current. The generation of the PIC is in our view due to the rectification of the optical electric field by the nonlinearity of the tunneling junction. To obtain a PIC with detectable magnitude an enhancement of the optical field...

  8. Measuring voltage transients with an ultrafast scanning tunneling microscope

    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 t...

  9. Site-directed deep electronic tunneling through a molecular network

    Electronic tunneling in a complex molecular network of N(>2) donor/acceptor sites, connected by molecular bridges, is analyzed. The 'deep' tunneling dynamics is formulated using a recursive perturbation expansion, yielding a McConnell-type reduced N-level model Hamiltonian. Applications to models of molecular junctions demonstrate that the donor-bridge contact parameters can be tuned in order to control the tunneling dynamics and particularly to direct the tunneling pathway to either one of the various acceptors

  10. Dynamic Instability of Tunnel in Blocky Rock Mass

    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.

  11. Estimation of tunnel subsidence effect on SuperKEKB

    The SuperKEKB uses the tunnel which was used for the KEKB B-factory. The tunnel subsidence during 10 years KEKB operation was reached about 25mm. In order to keep high luminosity, the vertical emittance growth due to tunnel subsidence should be suppressed by applying orbit and optics correction. In the following paper, the estimation of the vertical emittance growth by tunnel subsidence and the feasibility of the orbit and optics correction are reported. (author)

  12. Indium oxide as a possible tunnel barrier in spintronic devices

    We report the growth of ultra-thin indium oxide layers using the dc-magnetron sputtering method. We demonstrate that good quality tunnel barriers made of indium oxide can be routinely fabricated and employed in spintronic-related devices. Simple magnetic tunnel junctions (MTJs) were fabricated in a cross geometry using ex situ thermally evaporated cobalt and permalloy. Our best junctions obey the Rowell criteria for tunneling and exhibit a tunnel magnetoresistance of 15% at 100 K

  13. An Exact Solution for Quantum Tunneling in a Dissipative System

    Yu, Li Hua

    1996-01-01

    Applying a technique developed recently [1,2] for an harmonic oscillator coupled to a bath of harmonic oscillators, we present an exact solution for the tunneling problem in an Ohmic dissipative system with inverted harmonic potential. The result shows that while the dissipation tends to suppress the tunneling, the Brownian motion tends to enhance the tunneling. Whether the tunneling rate increases or not would then depend on the initial conditions. We give a specific formula to calculate the...

  14. Particles' Tunneling in Spherically Symmetric Spacetimes with Dark Matter

    Li, Guo-Ping; Zhou, Yun-Gang; Zu, Xiao-Tao

    2013-11-01

    Applying the Hamilton-Jacobi method, we investigate particles’ tunneling behavior in a spherically symmetric spacetime with dark matter. The tunneling rate and Hawking temperature at the event horizon are obtained. The result shows that the dark matter parameter β has an important influence on the Hawking temperature and the tunneling rate.

  15. Tunnel operator training with a conversational agent-assistant

    Buiel, E.; Lubbers, J.; Doesburg, W. van; Muller, T.

    2009-01-01

    A tunnel operator monitors and regulates the flow of traffic inside a tunnel. Tunnel operators need to train in a simulator regularly in order to maintain proficiency in handling incident situations. During quiet working hours, the operator has enough time for training. But generally at that time no

  16. CFD for Better Understanding of Wind Tunnel Tests

    Qin, N.

    2003-01-01

    In this paper, we discuss how CFD may be used for better understanding of wind tunnel tests. Three examples are used to illustrate the potential use of CFD to help the understanding of phenomena observed in the wind tunnel tests, to extend/derive simple aerodynamic criteria based on CFD, and to use CFD to improve the accuracy of wind tunnel measurements.

  17. Imaging of acute pancreatitis

    Merkle, Elmar M.; Goerich, Johannes [Department of Radiology, University Hospitals of Ulm, Steinhoevel Strasse 9, 89075 Ulm (Germany)

    2002-08-01

    Acute pancreatitis is defined as an acute inflammatory process of the pancreas with variable involvement of peripancreatic tissues or remote organ systems. This article reports the current classification, definition and terminology, epidemiology and etiology, pathogenesis and pathological findings, clinical and laboratory findings, and finally imaging findings of acute pancreatitis with emphasis on cross-sectional imaging modalities such as ultrasound, computed tomography, and magnetic resonance imaging. (orig.)

  18. Streptococcal acute pharyngitis

    2014-01-01

    Acute pharyngitis/tonsillitis, which is characterized by inflammation of the posterior pharynx and tonsils, is a common disease. Several viruses and bacteria can cause acute pharyngitis; however, Streptococcus pyogenes (also known as Lancefield group A β-hemolytic streptococci) is the only agent that requires an etiologic diagnosis and specific treatment. S. pyogenes is of major clinical importance because it can trigger post-infection systemic complications, acute rheumatic fever, and post-s...

  19. Acute generalized exanthematous pustulosis

    K.S. Dhillon

    2012-10-01

    Full Text Available Acute generalized exanthematous pustulosis (AGEP is a rare reaction pattern with a typical morphology and a short clinical course that in majority of cases is related to medication administration. It is an acute pustular eruption with unique clinical features, a rapid clinical course and a typical histopathology. Herein, we report the case of a patient with acute generalized exanthematous pustulosis for its classical presentation.

  20. Acute recurrent polyhydramnios

    Rode, Line; Bundgaard, Anne; Skibsted, Lillian;

    2007-01-01

    Acute recurrent polyhydramnios is a rare occurrence characterized by a poor fetal outcome. This is a case report describing a 34-year-old woman presenting with acute recurrent polyhydramnios. Treatment with non-steroidal anti-inflammatory drugs (NSAID) and therapeutic amniocenteses was initiated...... an enzyme-linked immunosorbent assay. As in normal pregnancies, amniotic prolactin levels decreased by 80% from highest to lowest value in this case of resolving acute recurrent polyhydramnios....

  1. Management Of Acute Migraine

    Mehndiratta M

    2002-01-01

    Pharmacotherapy for migraine involves treatment for the acute attack as well as using long-term prophylaxis in order to reduce the frequency and severity of the attacks. Based on severity, there are a number of drugs available to treat the acute attacks. For mild to moderate attacks, analgesics, NSAIDs and Ergotamine are effective but severe attacks may need Dihydroergotamine (DHE) or a triptan. Sumatriptan and the second generation triptans have revolutionized the acute treatment of migra...

  2. Atrial fibrillation (acute onset)

    Lip, Gregory Y. H.; Watson, Timothy

    2008-01-01

    Acute atrial fibrillation is rapid, irregular, and chaotic atrial activity of less than 48 hours' duration. It resolves spontaneously within 24 to 48 hours in over 50% of people. In this review we have included studies on patients with onset up to 7 days previously. Risk factors for acute atrial fibrillation include increasing age, CVD, alcohol abuse, diabetes, and lung disease.Acute atrial fibrillation increases the risk of stroke and heart failure.

  3. Mixed phenotype acute leukemia

    Ye Zixing; Wang Shujie

    2014-01-01

    Objective To highlight the current understanding of mixed phenotype acute leukemia (MPAL).Data sources We collected the relevant articles in PubMed (from 1985 to present),using the terms "mixed phenotype acute leukemia","hybrid acute leukemia","biphenotypic acute leukemia",and "mixed lineage leukemia".We also collected the relevant studies in WanFang Data base (from 2000 to present),using the terms "mixed phenotype acute leukemia" and "hybrid acute leukemia".Study selection We included all relevant studies concerning mixed phenotype acute leukemia in English and Chinese version,with no limitation of research design.The duplicated articles are excluded.Results MPAL is a rare subgroup of acute leukemia which expresses the myeloid and lymphoid markers simultaneously.The clinical manifestations of MPAL are similar to other acute leukemias.The World Health Organization classification and the European Group for Immunological classification of Leukaemias 1998 cdteria are most widely used.MPAL does not have a standard therapy regimen.Its treatment depends mostly on the patient's unique immunophenotypic and cytogenetic features,and also the experience of individual physician.The lack of effective treatment contributes to an undesirable prognosis.Conclusion Our understanding about MPAL is still limited.The diagnostic criteria have not been unified.The treatment of MPAL remains to be investigated.The prognostic factor is largely unclear yet.A better diagnostic cdteria and targeted therapeutics will improve the therapy effect and a subsequently better prognosis.

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

    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.

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

    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.

  6. Tunneling through a time-modulated barrier - relation to tunneling times

    We analyze tunneling through a time-modulated barrier, where transmitted particles may have absorbed or emitted modulation quanta. Buettiker and Landauer (BL) have suggested using the intensities of the side-bands to define a tunneling time. Our numerical simulations quantitatively confirm the analytical results of BL for these intensities. However, no cross-over at finite modulation frequency between distinct high-and low-frequency regions is found. Hence the procedure suggested by BL is, without refinements, unsuitable for defining a tunneling time. Furthermore, we examine analytically the transmitted wave-function in the adiabatic limit, and show that the related density and current involve both the dwell time, and the Buettiker time, defined in the context of a Larmor clock. This suggests the possibility that experiments, probing different aspects of the transmitted wave-function may yield different, but complementary information about the tunneling process. (orig.)

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

    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.

  8. delta-biased Josephson tunnel junctions

    Monaco, R.; Mygind, Jesper; Koshelet, V.;

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect the...

  9. Chaperone binding at the ribosomal exit tunnel

    Kristensen, Ole; Gajhede, Michael

    2003-01-01

    The exit tunnel region of the ribosome is well established as a focal point for interaction between the components that guide the fate of nascent polypeptides. One of these, the chaperone trigger factor (TF), associates with the 50S ribosomal subunit through its N-terminal domain. Targeting of TF...

  10. Tunnel Diode Discriminator with Fixed Dead Time

    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...

  11. Soliton excitations in Josephson tunnel junctions

    Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth

    1982-01-01

    A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...

  12. Wind Tunnel Measurements at Virginia Tech

    Fischer, Andreas; Bertagnolio, Franck

    2012-01-01

    In this section, the wind tunnel configuration used for aerodynamic and aeroacoustic measurement is described. Then, the validation of the method for evaluating far-field noise from surface microphones as described in Section 5 is presented. Finally, the design concept proposed in Section 6 is...

  13. Microscopic tunneling theory of long Josephson junctions

    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...

  14. Nonlinear tunneling in two-dimensional lattices

    Brazhnyi, V. A.; Konotop, V. V.; Kuzmiak, Vladimír; Shchesnovich, V. S.

    2007-01-01

    Roč. 76, č. 2 (2007), 023608.1-023608.14. ISSN 1050-2947 R&D Projects: GA MŠk(CZ) OC P11.001 Institutional research plan: CEZ:AV0Z20670512 Keywords : Bose-WEinstein condensation * tunnelling Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.893, year: 2007

  15. Tunnelling Problems in Older Sand Formations

    Nieuwenhuis, Jan Dirk; Verruijt, Arnold

    In its deepest stretch, 60 m below o.d. and water level, the Westerschelde tunnel trace below the estuary in the Southwestern part of the Netherlands, crosses the lower Oligocene Rupel clay (Boom clay) and the Sands of Berg. Expected problems such as small penetration rates and difficult steerability of the TBM did not occur but surprisingly high radial pressures deformed the shields tail section to such an extent that concrete rings of the permanent tunnel could not be emplaced. In retrospect after finishing the tunnel and cumbersome remedial measures the sands of Berg, known to be dense and strong, appear to exhibit very strong dilatancy when axially sheared by the TBM. Some buckling computations and an estimate of dilatant effects are presented together with educated (and now confirmed) guess work on diagenetic effects such as recrystallization and cementation. It seems wise to warn designers of shallow tunnels crossing tertiary sand formations for unexpected forces on shield and cutting wheel due to diagenetic structuring of these old sands.

  16. Analytic Solutions of Elastic Tunneling Problems

    Strack, O.E.

    2002-01-01

    The complex variable method for solving two dimensional linearly elastic problems is used to obtain several fundamental analytical solutions of tunneling problems. The method is used to derive the general mathematical representation of problems involving resultant forces on holes in a half-plane

  17. Trap spectroscopy and tunnelling luminescence in feldspars

    Comparative studies of tunnel luminescence, thermally stimulated luminescence (TSL), and trap energy spectra by the fractional glow technique (FGT) have been made both with sanidine and microcline feldspars. After X-irradiation at LNT these feldspars show intense tunnelling afterglow. As the temperature is raised, several TSL glow peaks may be observed, starting at 135 K. An intense peak at 250 K is common to all four investigated microclines. In samples of sanidine, tunnelling afterglow overcomes TSL up to 250-260 K. With sanidine and microcline samples, the distributions of trap activation energies vs temperature obtained by the FGT are continuous and quasi-linear. Maxima in the trap density are observed, indicating the presence of several kinds of stable defect structures. It may be concluded that below 100 K the thermally stimulated processes in the samples are frozen. Tunnelling recombination occurs between deeper localized states which are stable up to RT and higher. These results are attributed to the known 'Al-Si order-disorder' effect in feldspar crystals. It leads to the formation of wide continuous energy distributions of localized states. Donor-acceptor defects are caused by the association of Al3+ substituted in the centers of SiO4 tetrahedra and alkali ions in interstitial positions

  18. High-Performance Single Nanowire Tunnel Diodes

    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...

  19. Vector particles tunneling from BTZ black holes

    Chen, Ge-Rui; Huang, Yong-Chang

    2014-01-01

    In this paper we investigate vector particles' Hawking radiation from a BTZ black hole. By applying the WKB approximation and the Hamilton-Jacobi Ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.

  20. Vector particles tunneling from BTZ black holes

    Chen, Ge-Rui; Zhou, Shiwei; Huang, Yong-Chang

    2015-11-01

    In this paper we investigate vector particles' Hawking radiation from a Banados-Teitelboim-Zanelli (BTZ) black hole. By applying the Wentzel-Kramers-Brillouin (WKB) approximation and the Hamilton-Jacobi ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.

  1. Theoretical Analysis of Reinforcement Tunnel Lining Corrosion

    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.

  2. A lower bound on tunnel number degeneration

    Schirmer, Trent

    2014-01-01

    We prove a theorem which bounds Heegaard genus from below under special kinds of toroidal amalgamations of $3$-manifolds. As a consequence, we conclude $t(K_1\\# K_2)\\geq \\max\\{t(K_1),t(K_2)\\}$ for any pair of knots $K_1,K_2\\subset S^3$, where $t(K)$ denotes the tunnel number of $K$.

  3. 78 FR 46117 - National Tunnel Inspection Standards

    2013-07-30

    ... in the Federal Register on July 22, 2010, at 75 FR 42643. That proposal did not address the.../onlinepubs/nchrp/docs/NCHRP20-07 (261)--FR.pdf. C. Best Practices for Roadway Tunnel Design, Construction... ANPRM on November 18, 2008, (73 FR 68365) to solicit public comments regarding 14 categories...

  4. Tunneling spectra of graphene on copper unraveled

    Zhang, Xin; Stradi, Daniele; Liu, Lei;

    2016-01-01

    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 mech...

  5. Electron tunnelling into amorphous germanium and silicon.

    Smith, C. W.; Clark, A. H.

    1972-01-01

    Measurements of tunnel conductance versus bias, capacitance versus bias, and internal photoemission were made in the systems aluminum-oxide-amorphous germanium and aluminium-oxide-amorphous silicon. A function was extracted which expresses the deviation of these systems from the aluminium-oxide-aluminium system.

  6. Electron accelerator for tunneling through hard rock

    Earlier work demonstrated that intense sub-microsecond bursts of energetic electrons cause significant pulverization and spalling of a variety of rock types. The spall debris generally consists of sand, dust, and small flakes. If carried out at rapid repetition rate, this can lead to a promising technique for increasing the speed and reducing the cost of underground excavation of tunnels, mines, and storage spaces. The conceptual design features of a Pulsed Electron Tunnel Excavator capable of tunneling approximately ten times faster than conventional drill/blast methods are presented, with primary emphasis on the electron accelerator and only a brief description of the tunneling aspects. Of several candidate types of accelerators, a linear induction accelerator producing electron pulses (5 MV, 5 kA, 1.0 μs = 25 kJ) at a 360 Hz rate was selected for the conceptual example. This provides the required average electron beam power output of 9 MW. The feasibility of such an accelerator is discussed

  7. A Student-Built Scanning Tunneling Microscope

    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.…

  8. Towards high-speed scanning tunneling microscopy

    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

  9. The tunnel sealing experiment: a review

    The Tunnel Sealing Experiment (TSX), a major international experiment, demonstrating technologies for tunnel sealing at in situ full-scale, was conducted at Atomic Energy of Canada Limited's Underground Research Laboratory (URL). The objective of the experiment was to demonstrate technologies for construction of bentonite and concrete bulkheads, to quantify the performance of each bulkhead and to document the factors that affect the performance. It was not the purpose of the experiment to demonstrate an optimized bulkhead. Two bulkheads, one composed of low heat high performance concrete and the other of highly compacted sand-bentonite material, were constructed in a tunnel in unfractured granitic rock at the URL. The chamber between the two bulkheads was pressurized with water to 4 MPa in a series of steps over a two-year period. The ultimate pressure is representative of the ambient pore pressures in the rock at a depth of 420 m. The first phase of the TSX was conducted at ambient temperature (15oC) while a second phase involved heating the pressurized water between the bulkheads and the temperatures ultimately reached 65oC at thermistors near the upstream face of both bulkheads. Instrumentation in the experiment monitored parameters that are important indicators for bulkhead performance. Seepage was measured at both bulkheads and any other leakage points from the tunnel to maintain a water balance. The paper provides an overview of the project. (author)

  10. Tunneling times and the Hartman effect revisited

    In a recent review paper we proposed, within conventional quantum mechanics, new definitions for the sub-barrier tunnelling and reflection times. Aims of the present paper are: presenting and analysing the results of various numerical calculations (based on our equations) on the penetration and return times , , during tunneling inside a rectangular potential barrier, for various penetration depths xf; putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) D τT D τR for the time durations of transmission and reflection process; mentioning that our definition τT > for the average transmission time results to constitute an improvement of the ordinary dwell-time τDw formula; commenting upon some recent criticism by C.R. Leavens, on the basis of our new numerical results. We stress that our numerical evaluations confirm that our approach implied and implies, the existence of the Hartman effect: an effect that in these days (due to the theoretical connections between tunneling and evanescent wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna- indirect, but quite interesting, experimental verifications. At last, we briefly analyze some other definitions of tunnelling times. (author). 24 refs., 5 figs

  11. Electron accelerator for tunneling through hard rock

    Earlier work demonstrated that intense sub-microsecond bursts of energetic electrons cause significant pulverization and spalling of a variety of rock types. The spall debris generally consists of sand, dust, and small flakes. If carried out at rapid repetition rate, this can lead to a promising technique for increasing the speed and reducing the cost of underground excavation of tunnels, mines, and storage spaces. The conceptual design features of a Pulsed Electron Tunnel Excavator capable of tunneling approximately ten times faster than conventional drill/blast methods are presented with primary emphasis on the electron accelerator and only a brief description of the tunneling aspects. Of several candidate types of accelerators, a linear induction accelerator producing electron pulses (5 MV, 5 kA, 1.0 μs = 25 kJ) at a 360 Hz rate was selected for the conceptual example. This provides the required average electron beam power output of 9 MW. The feasibility of such an accelerator is discussed

  12. WIND TUNNEL SIMULATIONS OF POLLUTION FROM ROADWAYS

    A wind tunnel study has been conducted to examine the influence of roadway configurations and nearby structures on the flow and dispersion of traffic related pollutant concentrations within a few hundred meters of the roadway. The study focused four selected configurations (all w...

  13. Wind Tunnel Measurements at Virginia Tech

    Fischer, Andreas; Bertagnolio, Franck

    2012-01-01

    In this section, the wind tunnel configuration used for aerodynamic and aeroacoustic measurement is described. Then, the validation of the method for evaluating far-field noise from surface microphones as described in Section 5 is presented. Finally, the design concept proposed in Section 6 is verified.

  14. 3D numerical design of tunnel hood

    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...

  15. Tunnelling in Soft Soil: Tunnel Boring Machine Operation and Soil Response

    Festa, D.; Broere, W.; Bosch, J.W.

    2013-01-01

    Constructing tunnels in soft soil with the use of Tunnel Boring Machines may induce settlements including soil movements ahead of the face, soil relaxation into the tail void, possible heave due to grouting, long lasting consolidation processes, and potentially several other mechanisms. A considerable amount of the total soil displacements seems correlated with the passage of the TBM-shield. Even so, the TBM-induced soil displacements have so far only been coarsely correlated to the total set...

  16. Tunneling rates in electron transport through double-barrier molecular junctions in a scanning tunneling microscope

    Nazin, G. V.; S. W. Wu; Ho, W.

    2005-01-01

    The scanning tunneling microscope enables atomic-scale measurements of electron transport through individual molecules. Copper phthalocyanine and magnesium porphine molecules adsorbed on a thin oxide film grown on the NiAl(110) surface were probed. The single-molecule junctions contained two tunneling barriers, vacuum gap, and oxide film. Differential conductance spectroscopy shows that electron transport occurs via vibronic states of the molecules. The intensity of spectral peaks correspondi...

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

    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.

  18. Geological Hazards analysis in Urban Tunneling by EPB Machine (Case study: Tehran subway line 7 tunnel)

    Hassan Bakhshandeh Amnieh; Mohammad Saber Zamzam; Mozdianfard, M. R.

    2016-01-01

    Technological progress in tunneling has led to modern and efficient tunneling methods in vast underground spaces even under inappropriate geological conditions. Identification and access to appropriate and sufficient geological hazard data are key elements to successful construction of underground structures. Choice of the method, excavation machine, and prediction of suitable solutions to overcome undesirable conditions depend on geological studies and hazard analysis. Identifying and invest...

  19. Time Evolution of Tunneling in Thermal Medium -- Environment-driven Excited Tunneling --

    Matsumoto, Sh.; Yoshimura, M.

    2003-01-01

    Time evolution of tunneling phenomena proceeding in thermal medium is studied using a standard model of environment interaction. A semiclassical probability formula for the particle motion in a metastable state of one dimensional system put in thermal medium is combined with the formula of quantum penetration factor through a potential barrier, to derive the tunneling rate in medium. Effect of environment, its influence on time evolution in particular, is clarified in a real-time formalism. A...

  20. Inelastic electron tunnelling and noise spectroscopies in organic magnetic tunnel junctions with PTCDA barrier

    Aliev, Farkhad; Martinez, Isidoro; Hong, Jhen-Yong; Cascales, Juan Pedro; Andres, Pablo; Lin, Minn-Tsong

    2015-03-01

    The influence of internal barrier dynamics on spin, charge transport and their fluctuations in organic spintronics remains poorly understood. Here we present inelastic electron tunnelling spectroscopy (IETS) and low frequency noise (LFN) studies in magnetic tunnel junctions with thin (1.2-5nm) organic PTCDA barriers in the tunnelling regime at temperatures down to 0.3K. Shot noise is superpoissonian with a Fano factor exceeding in 1.5-2 times the maximum values reported for magnetic tunnel junctions with inorganic barriers, indicating spin dependent bunching in tunneling. IETS results show energy relaxation of tunneling electrons through the excitation of collective (librons) and internal (phonons) vibrational modes of the molecules. The bias dependence of the normalised 1/f noise studied up to 350mV reveals that the excitation of some phonon modes has a strong impact on LFN with over a 10-fold reproducible increase near some specific biases. The dependence of the IETS and LFN anomalies with the relative magnetic alignment of the electrodes will also be discussed.